FACULTY PUBLICATIONS

R.B.C. Henry, K.B. Kwitter, and J.A. Bates ’98

Astrophysical Journal, 531, 928 (2000)

This paper is the fourth and final report on a project designed to study carbon abundances in a sample of planetary nebulae (Pne) representing a broad range in progenitor mass and metallicity. We present newly acquired optical spectrophotometric data for three Galactic Pne, IC 418, NGC 2392, and NGC 3242, and combine them with UV data from the IUE Final Archive for identical positions in each nebula to determine accurate abundances of He, C, N, O, and Ne at one or more locations in each object. We then collect abundances of these elements for the entire sample and compare them with theoretical predictions of Pne abundances from a grid of intermediate-mass star models. We find some consistency between observations and theory, lending modest support to our current understanding of nucleosynthesis in stars below 8 solar masses in birth mass. Overall, we believe that observed abundances agree with theoretical predictions to well within an order of magnitude, but probably not better than to within a factor of two or three. However, even this level of consistency between observations and theory enhances the validity of published intermediate-mass stellar yields of carbon and nitrogen in the study of the abundance evolution of these elements.

D.A. Lubowich, Jay M. Pasachoff, Thomas J. Balonek, Thomas J. Millar, Christy Tremonti,
Helen Roberts, and Robert P. Galloway ’96

Nature, 405, 1025-1027, 29 June (2000)

The Galactic Centre is the most active and heavily processed region of the Milky Way, so it can be used as a stringent test for the abundance of deuterium (a sensitive indicator of conditions in the first 1,000 seconds in the life of the Universe). As deuterium is destroyed in stellar interiors, chemical evolution models predict that its Galactic Centre abundance relative to hydrogen is D/H = 5 x 10^-12, unless there is a continuous source of deuterium from relatively primordial (low-metallicity) gas. Here we report the detection of deuterium (in the molecule DCN) in a molecular cloud only 10 parsecs from the Galactic Centre. Our data, when combined with a model of molecular abundances, indicate that D/H = (1.7 ± 0.3) x 10^-6, five orders of magnitude larger than the predictions of evolutionary models with no continuous source of deuterium. The most probable explanation is recent infall of relatively unprocessed metal-poor gas into the Galactic Centre (at the rate inferred by Wakker). Our measured D/H is nine times less than the local interstellar value, and the lowest D/H observed in the Galaxy. We conclude that the observed Galactic Centre deuterium is cosmological, with an abundance reduced by stellar processing and mixing, and that there is no significant Galactic source of deuterium.

R.J.M. Olson and J.M. Pasachoff

Cambridge University Press, paperback version (1999)

J.M. Pasachoff

Prentice-Hall, Junior-high school science (2000)

J.M. Pasachoff

Prentice-Hall, Junior-high school science (2000)

J.M. Pasachoff

Houghton Mifflin Co., 4^th edition, The Peterson Field Guide Series (2000)

R.J.M. Olson and J.M. Pasachoff

Bull. Am. Astron. Soc. 31, #4, p. 1080 (1999)

We discuss several topics relating artists and their works with actual astronomical events in early Renaissance Italy to reveal the revolutionary advances made in both astronomy and naturalistic painting. Padua, where Galileo would eventually hold a chair at the University, was already by the fourteenth century (trecento) a renowned center for mathematics and nascent astronomy (which was separating from astrology). It is no wonder that when Enrico Scrovegni commissioned the famous Florentine artist Giotto di Bondone to decorate his lavish family chapel (c. 1303) that in the scene of the Adoration of the Magi Giotto painted a flaming comet in lieu of the traditional Star of Bethlehem. Moreover, he painted an historical apparition he recently had observed with a great understanding of its scientific structure: Halley’s Comet of 1301 (since Olson’s first publication of this idea in Scientific American we have expanded the argument in several articles and talks). While we do not know the identity of the artist’s theological advisor, we discuss the possibility that Pietro d’Abono, the Paduan medical doctor and “astronomer” who wrote on comets, might have been influential. We also compare Giotto’s blazing comet with two others painted by the artist’s shop in San Francesco at Assissi (before 1316) and account for the differences. In addition, we tackle the question how Giotto’s pupil, Taddeo Gaddi, who is documented as having been blinded by a solar eclipse, reflects his observations in his frescoes in Santa Croce, Florence (1328-30). Giotto also influenced the Sienese painter Pietro Lorenzetti, two of whose Passion cycle frescoes at Assisi (1316-20), contain dazzling meteor showers that hold important symbolic meanings in the cycle’s argument but more importantly reveal that the artist observed astronomical phenomena, such as the “radiant” effect, which was first recorded by Alexander von Humboldt in 1799 and only accepted in the nineteenth century. Lorenzetti also painted sporadic, independent meteors, which do not emanate from the radiant, demonstrating that he observed this phenomenon as well. (It is significant that these artists knew the differences between comets and meteors, facts which were not absolutely established until the eighteenth century.) We demonstrate that artistic and scientific visual acuity were part of the burgeoning empiricism of the fourteenth century that eventually yielded modern observational astronomy. Our work on comets has been funded in large part by the National Endowment for the Humanities and by the Getty Grant Program.

R.J.M. Olson and J.M. Pasachoff

Apollo, November, p. 58 (1999)

We examine a Durer painting in the National Gallery, London, whose reverse shows an astronomical object. We identify the object as a bolide, an exploding meteoroid, and not as a comet, as previously supposed.

J.M. Pasachoff

Proceedings of the NATO Advanced Study Institute on Advances in Solar Research at Eclipses, from Ground and from Space, J.P. Zahn and Magda Stavinschi, eds., Springer-Verlag, in press (2000)

J.M. Pasachoff

Newsletter of Commission 46 on the Teaching of Astronomy of the International Astronomical Union, #52, March pp. 3-4 (2000) physics.open.ac.uk/IAU46/newslet.html

J.M. Pasachoff

Included in Physicists’ Desk Reference (Springer-Verlag). (2000)

J.M. Pasachoff, B.A. Babcock, K.D. Russell ’00, S.K. May ’00

Abstract in the Bull. Am. Astron. Soc. 32, #2, 2000, pp. 750-751

We report on CCD observations of the corona from Rimnicu Vilcea, Romania, during the total solar eclipse of 11 August 1999. One experiment searched for oscillations in the 530.3-nm coronal green line at about 1 Hz by digitizing at 10 Hz, as a determination of the coronal oscillation spectrum to test models of magnetohydrodynamic heating. The optical system was improved in several ways since the 1998 expedition, as was monitoring of the filter. The series of images was aligned and Fourier transforms were examined for individual pixels and groups of pixels. No oscillations were clearly detected above the 1% level, though statistical analysis continues at this writing. A second experiment took a series of 36 images through one filter wheel that contained three filters near 400 nm and a second filter wheel containing polarizers at three angles plus a parfocal clear filter. The results include a polarization map of a quadrant of the sun and an attempt to map the coronal temperature. The temperature map uses techniques suggested by Cram (1976) through a determination of the extent to which scattering off high-temperature electrons wash out the photospheric Fraunhofer lines. Low-pass filtering of our resultant images show detail in the form of coronal loops but do not show much non-radial structure in the temperature variations. We also compare composite photographic observations with EIT images from eclipse day.

The expedition was supported by NSF grant ATM-9812408, National Geographic Society grant 6449-99, the Keck Northeast Astronomy Consortium, and NASA SOHO/EIT guest-investigator grant NRA-98-03-SEC-051.

P. Fortes, D. Bilbao, M. Fornerod, G. Rigaut, W. Raymond, Assistant Professor of Biology, and I.W. Mattaj

Genes & Develop., 13, 2425-2438 (1999)

The characterization of a novel yeast-splicing factor, Luc7p, is presented. The LUC7 gene was identified by a mutation that causes lethality in a yeast strain lacking the nuclear cap-binding complex (CBC). Luc7p is similar in sequence to metazoan proteins that have arginine-serine and arginine-glutamic acid repeat sequences characteristic of a family of splicing factors. We show that Luc7p is a component of yeast U1 snRNP and is essential for vegetative growth. The composition of yeast U1 snRNP is altered in luc7 mutant strains. Extracts of these strains are unable to support any of the defined steps of splicing unless recombinant Luc7 is added. Although the in vivo defect in splicing wild-type reporter introns in a luc7 mutant strain is comparatively mild, splicing of introns with nonconsensus 5' splice site or branchpoint sequences is more defective in the mutant strain than in wild-type strains. By use of reporters that have two competing 5' splice sites, a loss of efficient splicing to the capproximal splice site is observed in luc7 cells, analogous to the defect seen in strains lacking CBC. CBC can be coprecipitated with U1 snRNP from wild-type, but not from luc7, yeast strains. These data suggest that the loss of Luc7p disrupts U1 snRNP-CBC interaction, and that this interaction contributes to normal 5' splice site recognition.

L. Paliulis ’97, M. Byrne ’98, W. Raymond, Assistant Professor of Biology

Molec. Biol. of the Cell., 10, 130a (1999)

Cdc14 and Sfp1 comprise part of the network of proteins important for exit from mitosis. Cdc14, an essential dual-specificity protein phosphatase, indirectly regulates CLB-kinase activity. Sfp1, a split zinc-finger protein, plays multiple roles in cell cycle regulation. Cdc14 mutants arrest in late anaphase/early telophase when incubated at the restrictive temperature (36⁰C). Loss of function of sfp1 suppresses temperature-sensitivity of a cdc14-7 mutant. We sought a cellular explanation for the genetic interaction between cdc14 and sfp1. Although cdc14-7 sfp1 double mutants can grow at the restrictive temperature for cdc14, cells do not display wild-type morphology. Like cdc14-7 single mutants, cdc14-7 sfp1 double mutants at 36⁰C form a long projection, at the tip of which actin is polarized. In contrast to cdc14 mutants at 36⁰C, cdc14-7 sfp1 double mutants exhibit a diffuse spread of chromatin throughout the bud projection, with apparent spindle breakdown. Thus, loss of sfp1 function suppresses the temperature-sensitivity of cdc14 mutants without completely suppressing cdc14’s morphological defects. Sfp1 single mutants do not display long bud projections. Sfp1 cells have apparently normal actin and microtubule distributions. However, haploid sfp1 mutants have unusual bud scar patterns when compared to the spinal bud scar pattern of wild-type controls. We propose that the bud polarity defect of sfp1 mutants might contribute to the viability of cdc14-7 sfp1 double mutants.

S.J. Swoap, Assistant Professor of Biology, L. Olmsted and M. Genovesi

FASEB Journal, 14(4), A317 (2000)

S.J. Swoap, Assistant Professor of Biology, D.L. Adams, D.J. Seward, J. Haney, and M. Rudnicki

Med. Sci. Sports Exer., 32(5), 542 (2000)

S.J. Zottoli, Professor of Biology, F.R. Akanki ‘01, N.S. Hiza ‘02, D.A. Ho-Sang, Jr. ‘02, M. Motta ‘00, X. Tan ‘02, K.M. Watts ‘02, and E.A. Seyfarth

Biol. Bull., 197, 239-240 (1999)

The somata of large neurons can be found on the dorsal surface of the medulla oblongata (supramedullary neurons) and spinal cord (dorsal cells) in many teleost fish. Thirty-five to forty of these neurons are arranged in a single, median, longitudinal row, from the posterior end of the fissura rhomboidalis through the anterior portion of the spinal cord of the cunner, Tautogolabrus adspersus. Comparative physiological studies have indicated that these cells in the cunner and other teleost fish make electronic connections with one another, and that they respond to tactile inputs from the skin. We report on some physiological properties of these cells with the ultimate goal of determining their function.

Steven J. Zottoli, Professor of Biology, Donald S. Faber

The Neuroscientist, 6(1), 25-38 (2000)

The Mauthner cell (M-cell) is one of the few identifiable neurons in the vertebrate central nervous system. The ability to locate the M-cell, along with its inputs and outputs, has resulted in important findings in diverse areas of neurobiology including the molecular biology of neurons, synaptic and systems physiology, behavior, development, and neuroethology. The review provides a brief overview of the M-cell and then focuses on recent studies applying state-of-the-art techniques to address new issues and revisit old ones. One advantage of this preparation is the ability to conduct multidisciplinary studies from the subcellular to behavioral levels. For example, studies of activity-dependent changes in the strength of mixed electronic and chemical synapses on the M-cell’s lateral dendrite in vivo have been correlated with changes in the probability of eliciting a fast startle response initiated by the M-cell and its associated circuits. Similarly, it is now possible to image the activity of the M-cell and its homologs while observing motor behavior in zebrafish larvae. These approaches will provide direct tests of the functional properties of complex neural networks. Moreover, molecular mechanisms that underlie neuronal development can be tested directly with this neuron and its segmental homologs, because these cells occur in singular pairs at defined locations. Finally, after spinal cord injury, the M-cell’s axon regenerates, but does not follow its original course, and the startle response gradually recovers. The accessibility of the M-cell system offers the promise that strategies employed in restoring the function of a neural network will be revealed. Thus, we anticipate that the M-cell system will become a favored preparation for multidisciplinary studies on the neuronal basis of behavior and the recovery of behavior after injury.

Joseph W. Chihade, Assistant Professor of Chemistry,
& Paul Schimmel, The Scripps Research Institute

Proc. Nat. Acad. Sci. USA, 96(22), 12316 (1999)

A novel assembly of a catalytic unit for aminoacylation of an RNA microhelix is demonstrated here. This assembly may recapitulate a step in the historical development of tRNA synthetases. The class-defining domain of a tRNA synthetase is closely related to the primordial enzyme that catalyzed synthesis of aminoacyl adenylate. RNA binding elements are imagined to have been added so that early RNA substrates could be docked proximal to the activated amino acid. RNA microhelices that recapitulate the acceptor stem of modern tRNAs are potential examples of early substrates. In this work, we examined a fragment of E. coli alanyl-tRNA synthetase which catalyzes aminoacyl adenylate formation, but is virtually inactive for catalysis of RNA microhelix aminoacylation. Fusion to the fragment of either of two unrelated nonspecific RNA binding domains activated microhelix aminoacylation. While the fusion proteins lacked the RNA sequence specificity of the natural enzyme, their activity was within 1-2 kcal mol^-1 of a truncated alanyl-tRNA synthetase that has aminoacylation activity sufficient to sustain cell growth. These results show that, starting with an activity for adenylate synthesis, barriers are relatively low for building catalytic units for aminoacylation of RNA helices.

Birgit G. Koehler, Assistant Professor of Chemistry, Lee Y. Park, Associate Professor of Chemistry, & Lawrence J. Kaplan, Professor of Chemistry

J. Chem. Ed., 76, 1505-1509 (1999)

For a number of years we have been organizing and teaching a special outreach course during our Winter Study Program (the month of January). College students plan, develop, and present hands-on workshops to fourth grade students and their parents, with faculty providing logistical support as well as pedagogical advice. Recent topics have included “Forensic Science,” “Electricity and Magnetism,” “Chemistry and Cooking,” “Waves,” “Natural Disasters,” “Liquids,” “Pressure,” “Color and Light,” “Momentum and Inertia,” “Illusions,” and “The Senses.” The two-hour-long workshops, held one weekend on campus, emphasize hands-on experiments involving both the kids and the parents. Handouts for each workshop give instructions for doing several experiments at home. This program has been a great success for all involved: the college students gain insight into an aspect of science and what it takes to develop and teach that topic, the elementary school students participate in an exciting and challenging scientific exploration, and the parents have a chance to learn some science while spending time working on projects with their children. We provide an overview of the pedagogical aims of our current approach and a sense of the time-line involved in putting together such a program in a month.

J. Hodge Markgraf, Professor of Chemistry emeritus, & Carolyn A. Stickney ’00

J. Heterocycl. Chem., 37, 109-110 (2000)

The synthesis of N-phenyl lactams by phase transfer oxidation of N, N-(polymethylene)anilines with potassium permanganate is reported. Thus, N-phenylazetidine is oxidized to N-phenyl β-lactam, which constitutes the first preparation of a β-lactam in which the carbonyl function is introduced after formation of the four-membered ring.

Simon F. Mitchell, University of New Brunswick, Ron K. Pickerill, University of the West Indies, Bonnie A.B. Blackwell, Research Scientist, & Anne R. Skinner, Senior Lecturer

Caribbean Journal of Earth Science, 34, 1-4 (2000)

Two samples from the Port Morant Formation in southeastern Jamaica have been dated using electron spin resonance (ESR). Petrographic analysis showed some dissolution of the primary coralline aragonite as well as secondary mineral precipitation within the coral pore space in one sample, which also showed large associated uncertainties for accumulated doses calculated from the ESR growth curves. Therefore the age, 125 ± 7 kyr, for the sample probably represents a minimum age, being a weighted average of the date of the original skeletal aragonite and that for the secondary mineral phase. The second specimen yielded a single age of 132 ± 7 kyr. Although we feel that this is an accurate age, no single date can be considered to be totally reliable by itself. The ages suggest that at least part of the Port Morant Formation was deposited during the late Isotope Stage 6 and probably early Stage 5e. More dates from the unit, however, are necessary to confirm this conclusion.

Enrique Peacock-López, Associate Professor of Chemistry, Geoffrey Hutchison ’99,
& Leo L. Tsai ’98

Journal of Chemical Physics, 113, 6512-6515 (2000)

A variety of nonlinear chemical models, such as the Selkov-Schnakenberg, exhibit Turing patterns. The Templator, which is based on a minimal autocatalytic monomer-dimer system, is a newer two-variable model also able to show Turing patterns. Here we find that the dynamic behavior of the Templator is quite similar to other models with cubic nonlinearities. This is demonstrated through a series of computer simulations in two dimensions utilizing the cellular automata approach. The selection of parameter values is based on linear stability analysis, which provides a relatively simple method of predicting Turing pattern formation. The simulations reveal spot, labyrinth, and striped patterns, in agreement with the predictions of the analysis. Other behaviors, such as honeycomb patterns, are also observed. For some parameter values, we study transient spot replication. Our findings strongly suggest that the Templator may belong to the same class of models previously studied by Pearson.

Anne R. Skinner, Senior Lecturer

Applied Radiation and Isotopes, 52, 1311-1316 (2000)

Nearly twenty-five years ago, Motoji Ikeya demonstrated the potential of ESR dating. From a single substance (stalagmitic carbonate) and a single site (Akiyoshi Cavern), the field has grown to include materials from all over the world and time periods from a few thousand years ago to several million years ago. A vigorous program of instrumentation development has increased the precision of measurements as well as opening up new ways of collecting and interpreting spectra. Yet there are still references to ESR dating as an ‘experimental’ technique, one which cannot be trusted to produce dates that are accurate or precise. This paper discusses areas for which this is true and suggests what should be done to convince skeptics. Other areas for which the evidence suggests that ESR is at least as reliable as ‘standard’ methods are also be covered.

Anne R. Skinner, Senior Lecturer of Chemistry, Bonnie A.B. Blackwell, Research Scientist,
N. Dennis Chasteen, University of New Hampshire, Junlong M. Shao, University of New Hampshire, & Stephanie S. Min ’98

Applied Radiation and Isotopes, 52, 1337-1344 (2000)

Determining growth curves for ESR dating requires artificial irradiation of sample aliquots. This process can introduce short-lived effects not relevant to the geological or archaeological signal. Annealing to remove these effects is required to obtain accurate calculated ages. When the short-lived peaks are different from the dating signal, their disappearance is easy to monitor during annealing, and one can also be certain that the annealing process does not affect the dating signal. For tooth enamel, however, the short-lived signal is simply an unstable enhancement of the dating signal. The apparent D_e from growth curves created immediately after irradiation is considerably greater than post-annealing results although the shape of the curve is unchanged. A variety of annealing techniques have been used on an ad hoc basis. A detailed study of annealing both natural and artificially irradiated samples allows a rational choice of method, as well as confirming the lifetime of the dating signal. Corrections for other types of interference are also discussed.

John W. Thoman, Jr., Associate Professor of Chemistry,
& Andrew McIlroy, Sandia National Laboratories

Journal of Physical Chemistry A, 104, 4953-4961 (2000)

We measure absolute methylidyne (CH) radical concentrations in a series of rich 31.0-Torr (4.13 kPa) methane-oxygen-argon flames using cavity ringdown spectroscopy. Probing via the CH A2Δ-X2Π transition near 430 nm gives a sensitivity of 3x109 cm–3 for our experimental conditions, yielding a signal-to-noise ratio greater than 1000 for the strongest transitions observed. We measure profiles of CH mole fraction as a function of height above a flat-flame burner for rich flames with equivalence ratios of 1.0, 1.2, 1.4, and 1.6. These flames are modeled using the following mechanisms: 1) the GRI Mech 2.11, 2) a mechanism by Prada and Miller, 3) a modified GRI 2.11 mechanism, which employs a more realistic increased CH + O2 rate coefficient, and 4) the new GRI Mech 3.0. Generally good agreement between the models and the data is found, with the GRI 3.0 and modified 2.11 mechanisms best reproducing the data. The greatest discrepancies are observed at the richest stoichiometry, where all of the models predict a wider CH profile shifted further from the burner than experimentally observed.

Kim B. Bruce, Luca Cardelli, and Benjamin C. Pierce

Information and Computation 155, pp. 108-133 (1999).

Abstract: Recent years have seen the development of several foundational models for statically typed object-oriented programming. But despite their intuitive similarity, differences in the technical machinery used to formulate the various proposals have made them difficult to compare.

Using the typed lambda-calculus, F_≤^ω as a common basis, we now offer a detailed comparison of four models: (1) a recursive-record encoding similar to the ones used independently by Cardelli, Reddy, and Cook and others; (2) Hofmann, Pierce, and Turner's existential encoding; (3) Bruce's model based on existential and recursive types; and (4) Abadi, Cardelli, and Viswanathan's type-theoretic encoding of a calculus of primitive objects.

Brendan Davis Burns and Andrea Danyluk, Assistant Professor of Computer Science

Machine Learning, 38(1/2), 89-107 (2000)

Expert classification systems have proven themselves effective decision makers for many types of problems. However, the accuracy of such systems is often highly dependent upon the accuracy of a human expert’s domain theory. When human experts learn or create a set of rules, they are subject to a number of hindrances. Most significantly experts are, to a greater or lesser extent, restricted by the tradition of scholarship which has preceded them and by an inability to examine large amounts of data in a rigorous fashion without the effects of boredom or frustration. As a result, human theories are often erroneous or incomplete. To escape this dependency, machine learning systems have been developed to automatically refine and correct an expert’s domain theory. When theory revision systems are applied to expert theories, they often concentrate on the reformulation of the knowledge provided rather than on the reformulation or selection of input features. The general assumption seems to be that the expert has already selected the set of features that will be most useful for the given task. That set may, however, be suboptimal. This paper studies theory refinement and the relative benefits of applying feature selection versus more extensive theory reformulation.

Foster Provost, Bell Atlantic Science and Technology and Andrea Danyluk, Assistant Professor of Computer Science

Informatica, 23, 123-136 (1999)

The Workshop on AI Approaches to Time-Series Problems, jointly sponsored by the Fifteenth National Conference on Artificial Intelligence (AAAI-98) and the International Conference on Machine Learning (ICML-98), was held in Madison, Wisconsin, on 27 July 1998. The organizing committee consisted of Andrea Danyluk of Williams College, and Tom Fawcett and Foster Provost, both of Bell Atlantic Science and Technology. There were approximately 30 attendees.

The goal of the workshop was to bring together AI researchers who study time-series problems along with practitioners and researchers from related fields. These problems are of particular interest because of the large number of high-profile applications today that include historical time series (for example, prediction of market trends, crisis monitoring). The focus was primarily on machine-learning and data-mining approaches, but perspectives on statistical time-series analysis and state-space analysis (for example, work on hidden Markov models) were also included.

Karuppiah, Patrick Deegan, Elizath Araujo, Yinlei Yang, Gary Holness, Zhigang Zhu,
Barbara Staudt Lerner, Assistant Professor of Computer Science, Deepak Roderic Grupen and Edward Riseman

Proceedings of Int. Workshop on Self Adaptive Software, Oxford (2000)

Robot control in nonlinear and nonstationary run-time environments presents challenges to traditional software methodologies. In particular, robot systems in “open” domains can only be modeled probabilistically and must rely on run-time feedback to detect whether hardware/software configurations are adequate. Modifications must be effected while guaranteeing critical performance properties. Moreover, in multi-robot systems, there are typically many ways in which to compensate for inadequate performance. The computational complexity of high dimensional sensorimotor systems prohibits the use of many traditional centralized methodologies.

We present an application in which a redundant sensor array, distributed spatially over an office-like environment can be used to track and localize a human being while reacting at run-time to various kinds of faults, including: hardware failure, inadequate sensor geometries, occlusion, and bandwidth limitations. Responding at run-time requires a combination of knowledge regarding the physical sensorimotor device, its use in coordinated sensing operations, and high-level process descriptions. We present a distributed control architecture in which run-time behavior is both preanalyzed and recovered empirically to inform local scheduling agents that commit resources autonomously subject to process control specifications. Examples will be available from our search and rescue platform.

Barbara Staudt Lerner, Assistant Professor of Computer Science

ACM Transactions on Database Systems, (2000)

Schema evolution is a problem that is faced by long-lived data. When a schema changes, existing persistent data can become inaccessible unless the database system provides mechanisms to access data created with previous versions of the schema. Most existing systems that support schema evolution focus on changes local to individual types within the schema, thereby limiting the changes that the database maintainer can perform. We have developed a model of type changes incorporating changes local to individual types as well as compound changes involving multiple types. The model describes both type changes and their impact on data by defining derivation rules to initialize new data based on the existing data. The derivation rules can describe local and non-local changes to types to capture the intent of a large class of type change operations. We have built a system called Tess (Type Evolution Software System) that uses this model to recognize type changes by comparing schemas and then produces a transformer that can update data in a database to correspond to a newer version of the schema.

Rónadh Cox, Assistant Professor of Geosciences, et al.

Bulletin of Marine Sciences, 66, 269-277 (2000)

Recent decline in the diversity and percent cover of hard corals in reef environments worldwide has been extensively documented (Done, 1992; Gladfelter, 1982; Kuta and Richardson, 1996; Precht and Aronson, 1997; Rogers, 1990). To understand this decline, long-term records of reef environments (e.g. Aronson and Precht, 1997; Hughes, 1994; Precht and Aronson, 1997) are essential, but relatively few such records exist.

The subject of this study is a fringing reef in the U.S. Virgin Islands, the Mary Creek reef complex (MCRC), located within the St. John national park. In addition to the 1998 Winter Study field project reported here, the MCRC has been the site of several undergraduate research projects over the last thirty years (MacLeod, 1986; Mayall, 1993; Stoeckle, et al., 1968). In aggregate, these studies furnish a picture of large-scale change in the MCRC between 1968 and 1998. During this time, the reefs of St. John have been subject to increasing tourist visitation and impact from human settlements (e.g. Hubbard, et al., 1987; MacDonald, et al., 1997) and the island has been battered by several hurricanes (e.g. Rogers, et al., 1991), but the long-term effects of these phenomena are unknown because continuous reef-monitoring programs in the National Park have been undertaken only recently. No multi-decade studies have been published to date, and to the best of our knowledge, the MCRC is the only reef in the area for which such a continuous record exists.

Substantial changes have occurred in the MCRC over the last thirty years. In 1968 the reef crest zone was dominated by dense stands of Acropora palmata, and the reef was actively prograding; in 1986 few A. palmata colonies remained alive; and in 1998 only two living colonies, both small (about 30 cm high, with fronds less than 30 cm across), were recorded. During the same period the average water depth in the back-reef zone decreased, from about 1.5 m in 1968 to about 0.4 m in 1998, which corresponds to an average sediment aggradation rate of approximately 3.6 cm/year.

The present situation in the MCRC may result from a combination of factors, and it is possible that the affected coral communities will reestablish in the future. The interplay of environmental stimuli and their effects on reef ecology, and in particular the role of time, are only beginning to be understood (Done, 1992). Therefore, the existing 30-year record makes this site an excellent candidate for a long-term reef monitoring study.

David P. Dethier, Professor of Geosciences

New Mexico Geological Society Guidebook, 50, 371-378 (1999)

Quaternary base-level change in the northernmost Santo Domingo basin records the effects of damming and knickpoint migration upstream in White Rock Canyon and the influence of middle Pleistocene climate change. Quaternary changes were superimposed on complex base-level responses to changes in upstream sediment delivery, volcanism in the western Cerros del Rio and movement along the La Bajada fault zone in the late Pliocene and early Pleistocene. During Quaternary time, the Rio Grande cut the modern White Rock Canyon, initially transporting large quantities of sediment into the northernmost Santo Domingo basin, then incising this fill and underlying bedrock, stranding a series of inset, mainly fill terraces. Two principal pulses of aggradation, separated by >40 m of incision, can be distinguished in the surficial geologic record near the southern end of White Rock Canyon: an early Pleistocene episode (Q₁) that began with eruption of the upper Bandelier Tuff and another episode (Q₂) in middle Pleistocene time. Base-level lowering of ~60 m, punctuated by relatively brief periods of aggradation (Q₃ and Q₄), dominated geomorphic changes in the northernmost Santo Domingo basin from about 300 ka to present. Middle and late Pleistocene incision records decreased sediment load or increased stream power that resulted from upstream drainage evolution and pluvial/interpluvial cycles of increased amplitude.

P.E. Carrara

David P. Dethier, Professor of Geosciences

U.S. Geological Survey Miscellaneous Field Studies Map MF-2328 (1999)

About 150 landslides, including many previously unrecognized and unmapped deposits have been identified in the Los Alamos 30’ x 60’ quadrangle by reconnaissance surficial geologic mapping. These landslides range in size from small earthflows and rock slumps (less than 0.10 km²) to large earthflows, rock slumps, translational slides, debris avalanches, and complex landslides greater than 10 km² (Varnes, 1978). Landslide deposits underlie about 4 percent of the map area, and about 230 km of roadways are either underlain by landslides or are within 100 m of a landslide. This estimate was calculated on the basis of all roadways indicated on the Los Alamos 30’ x 60’ quadrangle base map (primary and secondary hard-surfaced highways, light-duty roads, unimproved roads, and trails).

David P. Dethier, Professor of Geosciences

Geological Society of America Abstracts with Programs, 31 (7), A-422 (1999)

The Lava Creek B ash bed (LCB), erupted from the Yellowstone caldera at about 0.64 Ma, provides a datum for measuring long-term incision rates along rivers from the Mississippi to west of the Rocky Mountains. Incision rates provide information about local rates of exhumation and can be used, in some cases, to estimate the rate of rock uplift or to assess the effect of climate change. The LCB is widely preserved in the western United States because of its substantial volume, broad initial dispersal and the aggrading environment into which it fell. Widespread drainage incision after LCB deposition isolated it from rapid fluvial erosion. Calculated rates of incision since early middle Pleistocene time range from less than 2 to 30 cm per thousand years. Rates are high in most areas near the Rocky Mountains and downstream along rivers draining extensive mountainous catchments and are lowest east of the High Plains and along the Snake River in Idaho. Incision rates along many, but not all, rivers decrease downstream. Increasing rates of downcutting along several major rivers in the late Pleistocene suggest that the balance of stream power, sediment transport and bed resistance was altered by some aspect of climate, including local drainage integration. Regional and temporal patterns of incision suggest that increased runoff from the Rocky Mountains governed middle and late Pleistocene downcutting. However, these data cannot be used to exclude regional rock uplift as a significant control of Pleistocene incision.

David P. Dethier, Professor of Geosciences

Geological Society of America Abstracts with Programs, 32(6), A-10 (2000)

Cordilleran ice retreated rapidly from the northern Puget lowland in latest Pleistocene time, fragmenting across deep channels and complex topography near the San Juan Islands and stabilizing only where the ice front grounded. Radiocarbon ages from shell in proximal glaciomarine sediment and local flow indicators suggest that ice-flow direction reoriented from S to SW, locally W during collapse of the tidewater margin of the Puget Lobe between about 13.6 and 12.8 ka (uncorrected shell ages). Ice retreated from Smith Island and central Whidbey Island by about 13.6 ka and collapsed to fluctuating tidewater margins N and E of Bellingham sometime after 13.0 ka. Striae and other indicators at elevations above 500 m suggest that the maximum Puget Lobe flowed toward 170^o. As ice thinned and retreated, striae cut at lower elevations and sparse drumlins mapped between the western San Juan Islands and the lower Skagit Valley record ice lobes: (1) confined by local topography, (2) flowing from different source areas, and (3) responding to calving drawdown. From N. Whidbey to Lummi Island, particularly near Deception Pass, a population of striae trends from 225 to 260^o. On N. San Juan Island, Waldron Island, and locally near Mt. Vernon ice flowed toward 220 to 250^o during retreat. North of Victoria and locally in the western San Juan Islands, however, low-elevation striae and drumlins trend near 160^o. Despite the diversity of directions, crosscutting striae are rare. At several sites field evidence and multiple populations of striae demonstrate that local flow directions reoriented >60^o, presumably as ice flow responded to the approach of calving margins. West and southwest-trending striae cut on N. Whidbey and Fidalgo Island after 13.5 ka suggest reorientation of local flow from a deeply embayed Puget Lobe. By about 13 ka, ice had disappeared from the Strait of Georgia leaving a complex, SW-flowing ice mass in the Noosack Valley.

Joe D. Dragovich and D.T. McKay, Jr., Dept. of Natural Resources, Division of Geology
David P. Dethier, Professor of Geosciences
James E. Beget, Univ. of Alaska

Geological Society of America Abstracts with Programs, 32(6), A-11 (2000)

Deposits of Glacier Peak eruptive events(s) are preserved in the lower Skagit River valley as 3-15 m high terraces adjacent to the Skagit River flood plain. The cities of Lyman, Sedro Woolley, and Burlington rest on terraces composed of dacite-rich sand and sandy gravel that is interpreted to be a non-cohesive laharic run-out. New outcrops, ¹⁴C ages, stratigraphic relations, dacite clast petrographic and geochemical data, and laharic sand composition suggest that the voluminous Kennedy Creek volcanic assemblage (KCA) of Beget (1981) reached the Puget Sound. The KCA is mostly a laharic-pyroclastic surge volcanic complex that originated from Glacier Peak volcano (GP). Near La Conner and the Puget Sound, 135 km downvalley from GP, the distal lahar can be traced as a 3-18 m-thick semi-continuous stratum using well and boring logs and isolated outcrops. This distal lahar is overlain by estuarine or deltaic sediments. The Skagit Valley segment of the lahar appears to originate from a single eruptive episode on the basis of the upward fining from crystal-dacite lithic sandy gravel (gravel 50-80% dacite) to sand (41-56% dacite). Hypersthene-hornblende-phyriac vesicular dacite clast samples from 18 lahar sites (near GP to La Conner) have similar REE, trace and major element geochemistry suggesting a single eruptive event. Charcoal in laharic sand near Lyman yielded an age of 4,780±80 yr BP, similar to the 5,100-5,500 yr BP age of the KCA. Along the flanks of GP, Beget (1982) estimated a total original volume of 23 km³ for the KCA. The >3,400 and <6,700 yr BP Dusty and Baekos Creek assemblages of Beget (1982) have an estimated total original volume of >10 km³, and could correlate with the KCA. Maximum-minimum lahar estimates in the lower Skagit River basin suggest an additional 2-3 km³ for the KCA. Thus, if our correlations are correct, the preserved KCA may have a volume >15 km³.

Markes E. Johnson, Professor of Geosciences
Jorge Ledesma-Vázquez, Facultad de Ciencias Marina, Univ. Autonoma de Baja California

Palaios, 14, 569-584 (1999)

During Late Pleistocene time, a shallow embayment covering more than six hectares near Punta San Antonio (Baja California Sur, Mexico) was flooded from the Gulf of California to a depth of about 14 m. More than 400 m of shoreline along the inner perimeter of this bay consists of fitted boulders derived from adjacent tectonic blocks of Cretaceous granodiorite and Miocene andesite. In most places, the 1-m-thick boulder bed unconformably blankets Miocene tuff related to the Upper Comondú Group. Elsewhere it sits on Lower Pliocene limestone belonging to the San Marcos Formation. Stabilized through extensive cementation by coralline red algae, the rim of the boulder bed forms a steep rocky shoreline reposed between 50^o and 70^o. Biological zonation is expressed both laterally and vertically by the remains of more than 30 species of marine intertidal organisms that colonized the uneven face of the boulder bed under varying conditions of wave activity and shore orientation. An exposed outer shore preserves vertical zonation among in situ mollusks differentiated between an upper zone, characterized by Modiolus capax, and a lower zone of Codakia distinguenda. A more sheltered inner shore shows vertical differentiation between an upper zone, including Ostrea palmula and Crucibulum scutellatum, and a lower zone still featuring Codakia distinguenda (but with different associates). At the rear of the embayment, a small protected cove was well sheltered from wave activity. Here an upper zone is dominated by large coral colonies of Porites californica, together with diverse mollusks, in contrast to a lower zone depleted in corals but retaining much the same mollusk assemblage.

Upper Pleistocene marine terraces correlated with oxygen isotope substage 5e follow elevations close to 12 m above present sea level throughout the surrounding gulf-coast region. The top of the extensive boulder bed at Punta San Antonio is 27.5 m above present sea level, but its seaward margin is connected by a continuous ramp to a 13-m level on the present shoreline. The boulder bed represents a local anomaly in average coastal uplift since the last interglacial epoch (corrected for eustasy) that is three and a half times the normal regional rate (17 cm/1,000 yr as opposed to 5 cm/1,000 yr). Ongoing uplift associated with the adjacent tectonic block that contributed granodiorite to the Punta San Antonio boulder bed is implicated.

Markes E. Johnson, Professor of Geosciences
David Backus, Research Associate
Jorge Ledesma-Vázquez, Facultad de Ciencias Marina, Univ. Autonoma de Baja California

Fifth International Meeting on Geology of the Baja California Peninsula, 13-14 (1999)

Basin-and-Range style extension opened the Gulf of California during the Late Miocene and left behind horst-and-graben structures with a prevailing north-south signature along the east margin of the Baja California Central Domain. Changeover to the present tectonic regime of transform-rift faults in the Gulf of California occurred in the Late Pliocene about 3.5 Ma. Surprisingly little evidence of transtensional tectonics related to the oblique plate boundary between the Baja California peninsula and Gulf of California is expressed in the Pliocene geology of the Central Domain. Previous studies in the Loreto Basin (by Umhoefer, et al., 1994 and by Bigioggero, et al, 1995) describe a thick accumulation of Upper Pliocene fan deltas overprinted by dextral-normal faults to the south and a volcanic center at Cerro Mencenares overprinted by normal faults to the north. A prominent fault on the east margin of Cerro Mencenares runs parallel to Arroyo El Mangle for more than 6 km. Transtensional tectonics are invoked as causal factors in the development of both areas, although local fault traces show little or no strike-slip motion and their orientation is typically north-south in agreement with the regional pattern of east-west crustal extension.

Our reconnaissance study of Pliocene geology on Ensenada el Mangle (25 km north of Loreto) shows that the southern Loreto Basin is isolated from Cerro Mencenares by a zone of tectonic quiescence in which limestone strata (<30 m thick) rest unconformably on Miocene andesite from the Comondú Group. These carbonates form low ramps on a dip of 6o that abut the southeast flank of Cerro Mencenares. The El Mangle ramps are comparable to those surrounding Pliocene islands at Punta Chivato and San Nicolas in the Bahía Concepción region. Age of the El Mangle ramps is Pliocene based on the abundant pectenid fossils Aequipecten abietis and Nodipecten subnodosus. Occurrence of the less common echinoid Clypeaster marquerensis indicates a mid- to Late Pliocene age. Very different strata border Ensenada el Mangle across the north side of a newly discovered fault zone, named “El Coloradito” for the red coloration along part of the exposed fault plane. The trend of this fault is unusual: N55W with a dip of 58^oS. Conformable in sequence, the first stratigraphic package is >125 m in thickness, and includes a basal andesite breccia, interbedded sandstones and mudstones, a columnar basalt, and a fossiliferous volcanic breccia, all diping 25-35^o E on a strike of N 34-40^oE. The top of this sequence is truncated by a single limestone bed with abundant oysters. It is <3 m in thickness and also thermally altered red in color. This marker has the appearance of a carbonate ramp, but its dip is oversteepened at 12^o (twice the normal value for the development of a synsedimentary ramp). A second series comprising the contiguous outer cliffs of Punta El Mangle is formed by volcaniclastic strata (>125 m thick) dipping 28^o NE on a strike of N10^oW. As yet undated, the distinctiveness of these two stratigraphic packages in contrast to the simplicity of adjacent Pliocene carbonate ramps on the Ensenada el Mangle points to major tectonic tilting of an allochthonous block. Notably, El Coloradito Fault Zone strikes offshore parallel to the transform faults associated with the Carmen and Farallon rifts in the Gulf of California. Landward in the opposite direction, it also fails to cross the prominent north-south fault that runs parallel to Arroyo El Mangle.

Paul Karabinos, Professor of Geosciences

Geological Society of America Abstracts with Programs, 31, A-370 (1999)

The Chester and Athens domes in southeastern Vermont are classic examples of mantled gneiss domes. The elongate pair, here referred to simply as the Chester dome, were interpreted as being cored by Middle Proterozoic basement rocks and unconformably mantled by an inner sequence of Late Proterozoic to Ordovician cover rocks and an outer sequence of Silurian and Devonian cover rocks (Doll, et al., 1961). The core and inner mantling sequence were deformed during the Ordovician Taconian orogeny and again, together with the outer mantling sequence, during the Devonian Acadian orogeny. More recently, many of the lithologic contacts in the Chester dome have been reinterpreted as thrust faults of presumed Taconian age (e.g. Ratcliffe, et al., 1997).

The most dramatic characteristic of the Chester dome, however, is not structural repetition of the highly distinctive lithologies but rather a zone of extreme attenuation of some of the inner mantling units. Around the southern half of the Chester dome, the zone of attenuation includes the Pinney Hollow, Ottauquechee, and Stowe Formations and is bounded by the Hoosac Formation (below) and Missisquoi Formation (above). The Missisquoi Formation is also dramatically thinned around the northern half of the Chester dome indicating that there the upper boundary of the attenuated zone is near the contact with the Silurian and Devonian rocks of the outer mantling sequence. The zone of attenuation includes rocks with spectacular spiral inclusion trails in garnet and equally spectacular oxygen-isotope zoning in garnet which indicates infiltration of externally derived fluids during garnet growth (Chamberlain and Conrad, 1993). In excellent exposures around the southern margin of the Chester dome, boudinaged layers are common in and near the attenuated zone and kinematic indicators suggest a tops-to-the-east sense of displacement. Garnets structurally below the zone of attenuation commonly contain textural unconformities indicating two stages of garnet growth. The second stage of garnet grew during Acadian decompression from 9.7 to 7.2 kbar (Vance and Holland, 1993). The available data are most consistent with the attenuated zone being a ductile low-angle normal fault which accommodated gravitational collapse during and after the emplacement of nappes in western New Hampshire and eastern Vermont.

Paul Karabinos, Professor of Geosciences
John N. Aleinikoff, U.S. Geological Survey
C. Mark Fanning, Australian National University

American Journal of Science, 299, 502-515 (1999)

Distinguishing Grenvillian basement rocks from pre-Taconian cover sequences in the Appalachians is a first-order problem essential for accurate structural interpretations. The Cavendish Formation in southeastern Vermont presents a classic example of this problem. Doll and others (1961) showed the Cavendish Formation as younger than the Middle Proterozoic Mount Holly Complex but older than the lithologically similar Cambrian Tyson and Hoosac Formations. More recently, the name Cavendish Formation has been informally abandoned and its metasedimentary units have been mapped as the Tyson and Hoosac Formations of Late Proterozoic to Cambrian age. In a radical departure from these interpretations, Ratcliffe and others (1997) reassigned metasedimentary rocks of the Cavendish Formation to the Mount Holly Complex based on an inferred intrusive relationship between them and a 1.42 Ga tonalite. This new age assignment, if correct, requires a completely new structural interpretation of the region.

SHRIMP and Pb evaporation ages of detrital zircons extracted from a quartzite layer from Cavendish Gorge near the proposed intrusive contact with the tonalite constrain the time of deposition of the Cavendish Formation. Grain shapes of the zircons vary from euhedral to nearly spherical. Virtually all the grains have pitted surfaces and show at least some rounding of edges and terminations; grains exhibit oscillatory zoning typical of zircons that crystallized from a magma. Single-grain Pb evaporation analyses of ten zircons and SHRIMP analyses of 15 zircons all yield ages less than 1.42 Ga. Seven of the grains are consistent with derivation from the Bull Hill Gneiss that postdates the Grenville orogenic cycle and predates deposition of the Cavendish Formation. Thus, the metasedimentary units of the Cavendish Formation should not be assigned to the Mount Holly Complex.

R. A. Wobus, Professor of Geosciences, and others

Rocky Mountain Geology, 34 (2), 289-312 (1999)

The ~1.08-Ga Pikes Peak composite batholith of central Colorado is a type example of an a-type granitic system. From the 1970s through the 1990s, details of the field relations, mineralogy, major and trace element compositions, and isotopic geochemistry of Pikes Peak rocks were documented, and they reveal the existence of two chemical groups, a potassic and a sodic series. The potassic series (~64-78 wt % SiO₂) includes the Pikes Peak Granite, which is mostly coarse-grained biotite ± hornblende syenogranite and minor monzogranite that dominates the batholith. The potassic series also includes fine- to medium-grained biotite granite found in numerous, small, late-stage plutons throughout the batholith. The sodic series is found in seven plutons comprised of a wide range of rock types (~44-78 wt % SiO₂), including gabbro, diabase, syenite/quartz syenite, and fayalite and sodic amphibole granite.

Differences in petrologic and geochemical characteristics between the sodic and potassic series indicate different petrogenetic histories. Major and trace element and strontium and oxygen isotopic data were used by some workers to hypothesize that mantle-derived alkali basalt underwent crystal fractionation and reaction with lower crustal rocks to generate syenitic magmas of the sodic series, which subsequently underwent further fractionation to produce sodic granites. Recent studies involving estimates of oxygen fugacities, along with additional trace element and neodymium isotopic data, also support a basalt fractionation model for the sodic series, but suggest only minor crustal involvement. Gabbros and diabase dikes associated with the sodic series appear to have been derived from mantle sources that previously had been affected by a subduction event, based on neodymium isotopic and trace element data.

Some workers propose that the potassic series also formed by fractionation of syenitic and/or basaltic magmas coupled with reaction with intermediate rather than lower crust. Other workers propose a model in which genesis of the potassic series was dominated by partial melting involving tonalitic sources, with fractionation and perhaps magma mixing playing subordinate roles in generating compositional diversity among the potassic granitoids. The Pikes Peak batholith thus formed by emplacement of at least two petrogenetically different granite types, which were emplaced close together in space and time and which exhibit geochemical characteristics typical of A-type granites.

Rachel Beane ’93
R. A. Wobus, Professor of Geosciences

Rocky Mountain Geology, 34 (2), 313-324 (1999)

Sugarloaf Peak is one of seven sodic plutons that lie within or adjacent to the ca. 1.08-Ga Pikes Peak batholith in central Colorado. This report represents the first study of the Sugarloaf plutons. Major element and modal analyses from the other six plutons (Lake George, Tarryall, Rampart Range, West Creek, Mt. Rosa, and Spring Creek), together with data presented here, indicate that sodic and potassic rocks from all of them were produced by fractional crystallization of mantle-derived basaltic magmas.

The Sugarloaf pluton is composed of fine-grained, medium-grained, coarse-grained, and pegmatitic syenite. The syenites lack quartz and are dominated by perthitic feldspar and ferrorichterite amphibole. The fined-grained syenite intrudes the medium- and coarse-grained syenites. The Sugarloaf pluton is surrounded by coarse-grained Pikes Peak Granite, which is the predominant rock type in the batholith. The linear arrangement of six of the seven sodic plutons parallel to major Precambrian fault trends suggests that the emplacement of Sugarloaf pluton may be rift-related.

The Sugarloaf syenites have high total alkalis, high FeO (total), low CaO, and low MgO concentrations. They are also enriched in rare earth elements (REE) and high field strength elements (HFSE). Pronounced trace element variation among the Sugarloaf syenites can be explained partially by models of fractional crystallization. A plot of Ba versus Sr shows that compositions of the syenites closely follow modeled fractionation vectors for potassium feldspar. The fractional crystallization trends show that fine-grained syenite is the most chemically evolved, consistent with field relations that show the fine-grained syenite intruded the medium- and coarse-grained syenites. Accessory mineral fractionation, release of volatiles, or removal of pegmatitic fluids also may have influenced geochemical variations among the Sugarloaf syenites.

R. A. Wobus, Professor of Geosciences

Geological Society of America Abstracts with Programs, 31 (7), A-386 (1999)

While no one questions the value of undergraduate research as a vital component of geoscience curricula, departmental limitations may preclude the implementation of such a program at some institutions. Limitations of faculty size, time, and resources may be especially acute in the small departments of liberal arts colleges, which may experience the additional burden of geographic isolation.

Several of these impediments can be surmounted if small departments create regional or even national consortia to collaborate especially in the area of undergraduate research, though other forms of sharing and cooperation (lab facilities, journal subscriptions, visiting speakers, etc.) may naturally and profitably result. And while collaboration is most effective in the summers during intercollegiate research projects in the field and lab, there are clear advantages to such programs operating year-round.

I will describe two undergraduate research consortia which I helped to establish – one regional with four colleges, one national with twelve. For 15 years these consortia have supported hundreds of undergraduates and tens of faculty who have worked as colleagues on dozens of research projects in the U.S. and abroad. Non-collegiate funding for these two alliances came largely from NSF and from the W. M. Keck Foundation. It is hoped that funding agencies will continue to recognize not only the educational value of consortial research for undergraduates, but also its economy and efficiency over supporting many smaller programs individually. Strategically, geoscience faculty should plan to work closely with their school’s administrators in charge of fund-raising and development; word of the new funding initiatives that eventually resulted in the formation of both the consortia to be described first came from such administrative personnel.

R. A. Wobus, Professor of Geosciences, and others

Geological Society of America Abstracts with Programs, 31 (7), A-261 (1999)

The ~1.08-Ga Pikes Peak batholith (PPB) of central Colorado is a “type” example of A-type granitic magmatism. Rocks of the PPB can be divided into two groups, based on chemical and mineralogical characteristics: (1) a potassic series (~64-78 wt % SiO₂; K/Na = 0.95-2.05), which is dominated by biotite granite and comprises >97% of PPB exposures, and (2) a sodic series (~44-78 wt % SiO₂; K/Na = 0.32-1.36), which includes gabbro/diabase, syenite/quartz syenite, and fayalite-sodic amphibole-bearing granites.

Gabbros and mafic dikes associated with the sodic granitoids have ε_Nd(T) (+3.5 to –3.0) that are lower than depleted mantle. Primitive mantle-normalized trace element patterns for PPB mafic rocks exhibit overall enrichments but Nb-Ta depletions, suggesting derivation from mantle sources that were previously affected by subduction-related processes. However, assimilation of 1.7-Ga arc-derived crust during ascent/emplacement cannot be ruled out.

The voluminous potassic granites are interpreted as partial melts derived from crustal sources of tonalitic composition, based on ε_Nd(T) values (-0.3 to –2.7, which overlap with values for exposed ~1.7-Ga tonalites/granodiorites in the region) and good matches between major element compositions of the potassic granites and experimental melts (e.g., Patiño Douce, 1997). In contrast, syenites and granites of the sodic series cannot be explained as crustal melts, but are interpreted as fractionation products of mantle-derived mafic magmas. High temperature and low oxygen fugacity estimates (e.g., Frost, et. al., 1988) support a fractionation origin for the sodic granitoid magmas, as do their ε_Nd(T) (-0.7 to +2.2) and trace element characteristics. Release of fluorine-rich volatiles and/or removal of pegmatitic fluids could have modified abundances of Ce, Nb, Zr, and Y in some sodic granitoid magmas.

Cathryn Manduca ’80
Eric Grosfils, Pomona College
R. A. Wobus, Professor of Geosciences

EOS, 80 (46), F111 (1999)

The Keck Geology Consortium was formed in 1987 by a grant from the W.M. Keck Foundation to increase opportunities for student and faculty research and to reduce faculty isolation. The consortium consists of the geology departments of 12 geographically distributed liberal arts colleges. Together they form a vibrant community that can sustain a large cooperative research program and attract funding. The consortium program has two goals: enhancing undergraduate education through collaborative research with faculty and providing substantive opportunities for faculty professional growth. Success is measured by the impact of the program on students, faculty, and alumni. Students and alumni give the program high marks for scientific training, developing interpersonal and communication skills, testing their interest in scientific careers, and assisting them in finding future opportunities. Faculty particularly value the opportunity to work with colleagues and the enhanced research opportunities that collaboration provides. They report that the research experiences feed back directly into their classroom teaching, to the benefit of all their students. The consortium program is sustainable because the benefits to individual students and faculty motivate their enthusiastic participation.

While the consortium was developed to address departmental needs, it also reflects and impacts national educational agendas. The consortium program has helped to promote the integration of research and undergraduate education nationally by documenting the impact of the program on students and faculty, through workshops and presentations, as a leader in community-wide discussion (e.g. Shaping the Future of Earth Science Education) and by providing an example of a successful program. There is no doubt that collectively we have had experiences, opportunities and impacts that we could not have had individually.

R. A. Wobus, Professor of Geosciences, and others

Precambrian Research, 98, 271-305 (1999)

The ~1.08 Ga anorogenic, A-type Pikes Peak batholith (Front Range, central Colorado) is dominated by coarse-grained, biotite ± amphibole syenogranites and minor monzogranites, collectively referred to as Pikes Peak granite (PPG). The batholith is also host to numerous small, late-stage plutons that have been subdivided into two groups (e.g. Wobus, 1976. Studies in Colorado Field Geology, Colorado School of Mines Professional Contributions, Colorado): (1) a sodic series (SiO₂ = ~44-78 wt %; K/Na = 0.32-1.36) composed of gabbro, diabase, syenite/quartz syenite and fayalite and sodic amphibole granite; and (2) a potassic series (SiO₂ = ~70-77 wt %; K/Na = 0.95-2.05), composed of biotite granite and minor quartz monzonite. Differences in major and trace element and Nd isotopic characteristics for the two series indicate different petrogenetic histories.

Potassic granites of the late-stage intrusions appear to represent crustal anatectic melts derived from tonalite sources, based on comparison of their major element compositions with experimental melt products. In addition, Nd isotopic characteristics of the potassic granites [ε_Nd (1.08 Ga) = -0.2 to –2.7] overlap with those for tonalites/granodiorites [ca. 1.7 Ga Boulder Creek intrusions; ε_Nd (1.08 Ga) = -2.4 to –3.6] exposed in the regions. Some of the partial melts evolved by fractionation dominated by feldspar. The late-stage potassic granites share geochemical characteristics with most of the PPG, which is also interpreted to have an anatectic origin involving tonalitic crust. The origin of monzogranites associated with the PPG remains unclear, but mixing between granitic and mafic or intermediate magmas is a possibility.

Erik W. Klemetti ’99
R. A. Wobus, Professor of Geosciences

Geological Society of America Abstracts with Programs, 32 (1), A-28 (2000)

The Silurian (?) Vinalhaven diabase (VHD) described by G. O. Smith (1907) rims the northwest edge of Vinalhaven Island in Penobscot Bay, ME. It occurs in a sill-like body about 150 m thick within the Seal Cove formation (Gates, in review) but locally contains a vesicular flow unit and a breccia of uncertain origin above the sill. Within the sill the VHD is a very homogenous dark gray massive rock characterized by 1-5 mm quartz “eyes” (xenocrysts) distributed throughout. Petrographically it is aphanitic with an intergranular (not diabasic) groundmass of andesine and clinopyroxene with slightly larger grains of spongy cellular plagioclase and quartz xenocrysts with ocellar rims.

XRF and INAA analyses show that this “diabase” in all its forms is geochemically an intermediate rock, with silica values ranging from 52 to nearly 62%. LILE’s are enriched from 10 to 40X MORB, and REE’s are slightly fractionated (LaN/LuN about 4) with a moderate negative Eu anomaly. According to the Zr/TiO2 vs. Nb/Y classification of Winchester and Floyd (1977), all samples plot as andesite or basaltic andesite. On tectonic discriminant diagrams for basaltic rocks, the VHD shows continental margin arc or mature island arc affinities, though these signatures may have been induced by hybridization. The petrographic and geochemical features of the VHD strongly suggest that it is a product of mixing of basaltic and granitic melts, evidence of which is vividly displayed by the plutonic rocks at the base of the Vinalhaven granite pluton in the southern part of the island (Wiebe and others, 1999) and in other volcano-plutonic centers of the Coastal Maine Magmatic Province such as Isle au Haut and Mt. Desert Island.

Jennifer L. Newton ’99
R. A. Wobus, Professor of Geosciences

Geological Society of America Abstracts with Programs, 32 (1), A-62 (1999)

The northwest part of Vinalhaven Island in Penobscot Bay, Maine, is underlain by a volcanic complex of probable Silurian age. In stratigraphic order the units, as defined by G. O. Smith (1907), are the Thorofare Andesite, the Vinalhaven Diabase (see Klemetti and Wobus, this volume), and the Vinalhaven Rhyolite (VHR). Gates (in review) has proposed the name “Perry Creek formation” for the bedded volcaniclastic deposits beneath the flow-landed rhyolites of the VHR. This report describes the Perry Creek lithologies in some detail and provides extensive new geochemical data for the VHR.

The Perry Creek formation grades from basal layers of well-sorted maroon siltstones and sandstones (some containing the trace fossil Chondrites into tuffs and breccias with fragments of mafic to intermediate volcanics. The upper layers are breccias dominated by pebble-sized clasts of flow-banded rhyolite. Most horizons are matrix supported (lahars?) and some contain low-angle cross-beds. The base of the VHR as defined by Gates is a thick breccia layer with cobble to boulder-sized fragments of flow-banded rhyolite. The remainder of the VHR contains a wide variety of extraordinarily well preserved volcanic textures and structures: air-fall tuffs (some with accretionary lapilli), welded tuffs, tuff breccias, and flows and autobreccias with well-defined flow-banding (locally containing spherulites up to 15 cm in diameter). Some of the thickest flows could be remnants of exogenous domes. Geochemically most of these rocks are true rhyolites, though early air-fall tuffs plot as rhyodacites which are chemically similar to the Vinalhaven Granite in the southern half of the island. MORB-normalized spider diagrams for the rhyolites and granites show parallel patterns, and both units plot on the boundary between “within-plate” and “volcanic-arc” fields in tectonic discriminant diagrams (consistent with other volcano-plutonic assemblages of similar age to the northeast in coastal Maine).

Colin C. Adams, Mark Hopkins Professor of Mathematics

Alan Reid

Proceedings of the Cambridge Philosophical Society, 128, 103-110 (2000)

The systole length of a 3-manifold is the length of the shortest geodesic in the manifold. We prove that if L is a knot in the 3-sphere S³ with hyperbolic complement then the systole length of the complement is at most 7.35534... . Improved bounds are obtained for particular types of knots and for manifolds containing particular surfaces.

Colin C. Adams, Mark Hopkins Professor of Mathematics

K. Foley, J. Kravis ‘98, R. Dorman, S. Payne

Journal of Combinatorial Theory, Series B, 77, 1, 96-120 (September 1999)

In this paper we generalize the concept of alternating knots to alternating graphs and show that every abstract graph has a spatial embedding that is alternating. We also prove that every spatial graph is a subgraph of an alternating graph. We define n-composition for spatial graphs and generalize the results of Menasco on alternating knots to show that an alternating graph is n-composite for n=0,1,2,3 if and only if it is “obviously n-composite'” in any alternating projection. Moreover, no closed incompressible pairwise incompressible surface exists in the complement of an alternating graph. We then generalize results of Kauffman, Murasugi, and Thistlethwaite to prove that the crossing number of an even-valent rigid-vertex alternating spatial graph is realized in every reduced alternating projection with no uncrossed cycles and, if the graph is not 2-composite, the crossing number is not realized in any non-alternating projection. We give examples showing that this result does not hold for graphs with vertices of odd valence or graphs with uncrossed cycles.

Colin C. Adams, Mark Hopkins Professor of Mathematics

Michigan Mathematics Journal, 46, 3, 515-531 (1999)

Given a choice C of one of a set of specified isometry types of maximal cusps, it is shown that three disjoint simple closed curves can be removed from any closed 3-manifold or two disjoint simple closed curves can be removed from a cusped hyperbolic 3-manifold so that the resulting manifold M' is hyperbolic and one of the cusps in M’ is isometric as a maximal cusp to C. The isometry types of the possible maximal cusps include ones of volume 4, 6, 2√3, 2(1+√3) and 8√3/5. If one more curve is removed, maximal cusps of volumes 8, 10, 2√7, √11 and √15 can also be realized. A similar result is proved for totally geodesic boundaries as well..

Colin C. Adams, Mark Hopkins Professor of Mathematics

Mathematically Bent Column, Mathematical Intelligencer, 22, 1, 21-22 (2000)

Mathematics as mountain climbing.

Colin C. Adams, Mark Hopkins Professor of Mathematics

Mathematically Bent Column, Mathematical Intelligencer, 22, 2, 26-27 (2000)

Mathematics through the personals.

Edward B. Burger, Associate Professor of Mathematics

Michael Starbird

Key College Press in cooperation with Springer-Verlag, (2000)

In this new innovative textbook, the authors put special emphasis on the deep ideas of mathematics and present the subject in a lively and entertaining fashion. Throughout the text, the authors present the subject as a way of thinking that can be used to solve problems, analyze situations, and model the world around us. The book is accompanied by a kit including 3D glasses, CD-ROM, and other hands-on manipulatives.

Edward B. Burger, Associate Professor of Mathematics

Monatshefte fur Mathematik, 128, 201-209 (2000)

Here we provide a necessary and sufficient condition on the partial quotients of two real quadratic irrational numbers to insure that they are elements of the same quadratic number field over Q. Such a condition has implications to simultaneous diophantine approximation. In particular, we deduce an improvement to Dirichlet’s Theorem in this context which, as an immediate consequence, shows the Littlewood Conjecture to hold for all numbers from the same quadratic number field.

Edward B. Burger, Associate Professor of Mathematics

The Journal of Number Theory, 82, 12-24 (2000)

Beginning with an improvement to Dirichlet’s Theorem on simultaneous approximation, in this paper we introduce an algorithm, in sympathy with the classical continued fraction algorithm, to generate the sequence of best approximates to certain simultaneous systems. We then produce best possible upper bounds for the associated diophantine inequalities. In addition, we consider implications within the geometry of numbers and investigate the converse of the sharpened version of Dirichlet’s result. Finally, we close with some remarks on the Littlewood Conjecture in this context.

Edward B. Burger, Associate Professor of Mathematics

Jonathan Todd ’96

Fibonnaci Quarterly, 38, 136-144 (2000)

Let a be a real quadratic irrational and m(a) the Lagrange constant for a. For any c, 0 < c < m(a), we explicitly compute the finite list of positive integers q satisfying q||aq|| < c, and determine the optimal lower bound for c to ensure solvability of the inequality. This extends and generalizes results of Tognetti, Van Ravenstein and Winley.

Edward B. Burger, Associate Professor of Mathematics

Michael Starbird

The Notices of the American Mathematical Society, 47, (2000)

In this opinion piece, the authors examine how the mathematics community could inspire and entice others to explore mathematics.

Victor E. Hill IV, Thomas T. Read Professor of Mathematics

Chapman & Hall Publishers, (November 1999)

Group representation and character theory is both elegant and practical, with important applications to quantum mechanics, spectroscopy, crystallography, and other fields in the physical sciences. This text offers an easy-to-follow introduction to the theory of groups and of group characters. Group theory is covered through the Sylow Theorems and the full subgroup structure of A₅. Numerous character tables are worked out in full, along with a presentation of real and induced characters that lead to the table for S₅.

Susan Loepp, Assistant Professor of Mathematics

Journal of Pure and Applied Algebra, 148, 191-207 (2000)

In this paper, we construct examples of local unique factorization domains so that not only can the dimension of the generic formal fibers of these domains be controlled, but also the dimension of the formal fibers for infinitely many height one prime ideals.

Frank Morgan, Dennis Meenan (’54) Centennial Professor of Mathematics

Math Assn. Amer., (2000)

A popular book based on the TV show and column. Illustrated by James Bredt.

Frank Morgan, Dennis Meenan (’54) Centennial Professor of Mathematics

Academic Press, Third Edition, (2000)

An easy-going, illustrated introduction for the newcomer to this fast-growing and somewhat technical field. The third edition presents, for the first time in print, the recently announced proofs of the Double Bubble Conjecture (equal and unequal volumes) and the Hexagonal Honeycomb Conjecture, as well as treatments of the Weaire-Phelan counterexample to Kelvin’s Conjecture and Almgren’s optimal isoperimetric inequality. There is also a new chapter on immiscible fluids and crystals. In these areas, undergraduates have made important contributions.

Frank Morgan, Dennis Meenan (’54) Centennial Professor of Mathematics

Kenneth Brakke

J. of Geom. Anal., 8, 749-767 (1998)

We show that adding slight thickness to a soap film shaped like an X leaves it unstable, although adding much thickness makes it stable. Analogous questions about other singularities remain controversial.

Frank Morgan, Dennis Meenan (’54) Centennial Professor of Mathematics

Math Horizons, (September 1999)

Popular account of a surprising new way to partition space into unit volumes, upsetting the 100-year-old Kelvin conjecture.

Frank Morgan, Dennis Meenan (’54) Centennial Professor of Mathematics

J. Geom. Anal., 8, (1998)

Recollections of student and colleagues.

Frank Morgan, Dennis Meenan (’54) Centennial Professor of Mathematics

Congressional Quarterly Researcher, 9, 899 (October 15, 1999)

Congress needs to know that the millennium begins with 2001.

Frank Morgan, Dennis Meenan (’54) Centennial Professor of Mathematics

MAA Web Page, (1998-present)

Biweekly column with questions, answers, and prizes. Available at the MAA web page at www.maa.org.

Jerome Reiter, Assistant Professor of Mathematics

Amer. Math. Monthly, 107, 24-32 (2000)

Increasingly, causal questions are being answered with statistics. For both scientists and consumers, it has become important to understand how valid causal studies can be designed and how suspicious studies can be identified. This paper aims to further these understandings by explaining the statistical principles and techniques that underlie valid studies of causal relationships. It explains how randomized experiments yield reliable estimates of causal effects and describes techniques used to estimate causal effects in non-randomized studies.

Cesar E. Silva, Professor of Mathematics

Terry Adams

Ergodic Theory and Dynamical Systems, 19, 837-850 (1999)

We define staircase Z^d actions. We first prove that staircase Z^d actions satisfying a general condition are mixing. Then we describe how to extend the results to the staircase Z^d actions. Thus, we have constructed explicitly rank one mixing Z^d actions which include natural analogues to the well-known staircase transformation.

Cesar E. Silva, Professor of Mathematics

With E. Muehlegger ’97, A. Raich ’98, M. Touloumtzis ’96, B. Narasimhan ’97 and W. Zhao

Colloquium Mathematicum, 82, (2), 167-190 (1999)

We construct infinite measure-preserving and nonsingular rank one Z^d-actions. The first example is ergodic infinite measure preserving but with non-ergodic, infinite conservative index, basis transformations; in this case we exhibit sets of increasing finite and infinite measure which are properly exhaustive and weakly wandering. The next examples are staircase rank one infinite measure preserving Z^d-actions; for these examples we show that the individual basis transformations have conservative ergodic Cartesian products of all orders, hence infinite ergodic index. We generalize this example to obtain a stronger condition called power weakly mixing. The last examples are nonsingular Z^d-actions for each Krieger ratio set type with individual basis transformations with similar properties.

Daniel P. Aalberts, M.S.L. du Croo de Jongh, Leiden University, Brian F. Gerke ’99, and
Wim van Saarloos, Leiden University

Physical Review A, 61, 040701 (2000)

We analyze the coherent dynamics of optically excited alkenes in a fully correlated 3D tight-binding model with extended Hubbard interactions. The scenario that emerges is that the steric repulsive interactions are the driving force behind ultrafast cis-trans photoisomerizations. This resolves the apparent discrepancy between values for the torsional stiffness obtained from band structure potentials and from vibrational spectra. The mechanism is illustrated in quantitative detail for ethylene and is also shown to yield a promising scenario for the coherent dynamics of molecules like retinal.

S.R. Bolton, R.A. Jenks ’98, C.N. Elkinton ’98, and G. Sucha

IEEE LEOS newsletter, 14(2), 7, (2000)

In the last decade ultrafast laser science and technology has undergone revolutionary growth. Femtosecond sources are now used routinely as probes of ultrafast processes in biological, chemical, and physical systems, as well as for applications in communications and medicine. All femtosecond lasers rely on intensity dependent optical response-that is on optical nonlinearity, to produce and shape the pulses. The formalism of nonlinear dynamics and chaos explains the behavior of complex systems with such nonlinear interactions, and can predict their instabilities. Far from being a mere mathematical curiosity, the nonlinear dynamics approach to lasers has yielded a wealth of basic knowledge pertinent to laser development, as for example in controlling semiconductor laser instabilities. Despite their general utility, these approaches have only recently been applied to the study of femtosecond laser systems. Here we briefly describe our work on two such systems: the additive pulse modelocked laser (APM) operating at 1.55 microns, and the Kerr lens modelocked Titanium Sapphire laser (KLM) operating at 800nm.

U. Neukirch, S.R. Bolton, L.J. Sham, and D.S. Chemla

Physical Review B, 61(12), R7835 (2000)

The nonlinear optical response of excitons in a single ZnSe quantum well is investigated by pump-probe measurements. In counter-circular polarization configuration at negative delay, Δt, spectral oscillations are observed the period of which is energy dependent. Whereas at energies above the 1S exciton the usual E_pp=h/Δt dependence is found, the period strongly deviates from that value at energies below the exciton. Model calculations reveal that this behavior is caused by the bound biexciton state in the four-particle correlations.

U. Neukirch, S.R. Bolton, N.A. Fromer, L.J. Sham, and D.S. Chemla

Physical Review Letters, 84(10), 2215, (2000)

The influence of four-particle correlations on the nonlinear response of a semiconductor microcavity is determined by a pump-and-probe investigation. Experiments are performed on a specially designed non-monolithic microcavity which contains a single ZnSe quantum well. In this system, the biexciton binding energy exceeds both the normal-mode splitting between exciton and cavity mode and all relevant damping constants. Strong spectral features below the excitonic resonance are observed in the nonlinear response. These features are unique to the counter-polarized configuration which allows for excitation of the bound biexciton state. Comparison with model calculations shows that in this case the coherent nonlinearity is completely dominated by biexciton-exciton interactions beyond the Hartree-Fock approximation.

Y.M. Liu, J.A. Li, D.Y. Chen, L. Li, K.M. Jones, B. Ji, R.J. Le Roy

J. Chem. Phys., 111 (8), 3494 (1999)

Transitions into the doubly excited Na₂ 13Sg- state have been analyzed using near-dissociation expansions (NDE) to represent the vibrational energies and inertial rotational constants, while the centrifugal distortion constants were held fixed at “mechanically consistent” values calculated from the Rydberg–Klein–Rees (RKR) potential implied by those G(upsilon) and B-upsilon functions. The input data cover the range upsilon = 0 to 57 and N up to 47, and the fit yields upsilon(D) = 61.41(±0.10) and D-0 = 3385.70(±0.2) cm-1.

K.M. Jones, P.D. Lett, E. Tiesinga, et al.

Physical Review A, 61, 012501 (2000)

Line shapes observed in photoassociation spectroscopy of ultracold (T<1 mK) atoms are asymmetric and the peak of the line is shifted by a temperature-dependent amount from the zero-temperature threshold. In principle, calculating the line shape requires a full knowledge of both the ground- and excited-state potentials. We demonstrate here that an approximation based on the Wigner threshold law for scattering yields a relatively simple expression which allows one to extract line positions and linewidths directly from the data. The formula contains a few parameters (threshold frequency, linewidth, temperature, height) and does not require a detailed knowledge of the molecular potentials involved. We illustrate the utility of this approach with examples for Na photoassociation at 500 mK and also discuss the limitations of the approach.

A. Amelink, K.M. Jones, P.D. Lett, et al.

Physical Review A, 61, 042707 (2000)

We have performed photoassociation spectroscopy to study the doubly excited states of Na₂ involved in the associative ionization of colliding Na(3P) atoms. Rovibrational levels of two doubly excited potentials connected to the P3/2 + P3/2 asymptote, one of 0u+ and one of 1u symmetry, have been identified. These two doubly excited potentials dominate the route to ionization used in photoassociation experiments of cold Na. Binding energies and rotational constants for all the vibrational levels with binding energies <50 GHz have been measured. The asymptotic potentials and short-range ionization probabilities are extracted from the data.

Kevin Jones, et al.

Physical Review A, 62, 013408 (2000)

We have measured the rate of production of Na₂+ ions in collisions of ultracold Na atoms held in a magneto-optical trap (MOT) as a function of probe laser detuning using a single-color probe beam. The ion rate is measured with the atoms mainly in the 3S(f = 2) level (“bright MOT”) or the 3S(f = 1) level (“dark MOT”). Using recent experimental information about the doubly excited autoionizing states of Na₂, we find that the large structures in the first 5 GHz red of the atomic transition frequency are due to a doubly resonant excitation process with levels in the 0g- potential (asymptotically connected to 3S1/2 + 3P3/2) as the intermediate states, and levels in the 0u- and 1u potentials (asymptotically connected to 3P3/2 + 3P3/2) as the final autoionizing states. We can account for nearly all of the observed structure in this region of the spectra for both the bright and dark MOT.

D.S. Richardson, R.N. Lyman ’99, and P.K. Majumder

Physical Review A, 62, 012510 (2000)

Using a frequency-doubled diode laser system, we have measured the hyperfine splitting in the (6s²7s)7S_1/2 excited state of the two naturally occurring thallium isotopes. For thallium ²⁰⁵T1 and ²⁰³T1 we find frequency intervals of 12294.5(1.5)MHz and 12180.5(1.8)MHz respectively. This measurement addresses an earlier discrepancy in measured values for these intervals. At the same time, we have measured, with a factor of fifty improved precision, the ²⁰⁵T1-²⁰³T1 isotope shift within the 378 nm 6P_1/2-7S_1/2 transition.

William K. Wootters, Professor of Physics

Quantum Communication, Computing, and Measurement 2, ed. by P. Kumar, et al., Kluwer Academic/Plenum, New York, 2000.

At least three distinct information-theoretic measures of quantum entanglement have been proposed in recent years. This paper highlights one of them, the entanglement of formation, as well as a related quantity called the tangle. The tangle can be used to express a simple law of entanglement, limiting the extent to which a single qubit may be simultaneously entangled with each of two other qubits.

Valerie Coffman, Joydip Kundu, and William K. Wootters, Professor of Physics

Physical Review A, 61, 052306, (2000)

Consider three qubits A, B, and C which may be entangled with each other. We show that there is a trade-off between A’s entanglement with B and its entanglement with C. This relation is expressed in terms of a measure of entanglement called the concurrence, which is related to the entanglement of formation. Specifically, we show that the squared concurrence between A and B, plus the squared concurrence between A and C, cannot be greater than the squared concurrence between A and the pair BC. This inequality is as strong as it could be, in the sense that for any values of the concurrences satisfying the corresponding equality, one can find a quantum state consistent with those values. Further exploration of this result leads to a definition of an essential three-way entanglement of the system, which is invariant under permutations of the qubits.

Alexander Staller, Steven A. Sloman, and Talia Ben-Zeev, Assistant Professor of Psychology

Memory & Cognition, 28, 396-405

Perspective effects in the Wason four-card selection task occur when people choose mutually exclusive sets of cards depending on the perspective they adopt when making their choice. Previous demonstrations of perspective effects have been limited to deontic contexts—that is, problem contexts that involve social duty, like permissions and obligations. In three experiments, we demonstrate perspective effects in nondeontic contexts, including a context much like the original one employed by Wason (1966, 1968). We suggest that perspective effects arise whenever the task uses a rule that can be interpreted biconditionally and different perspectives elicit different counterexamples that match the predicted choice sets. This view is consistent with domain-general theories but not with domain-specific theories of deontic reasoning—for example, pragmatic reasoning schemas and social contract theory—that cannot explain perspective effects in nondeontic contexts.

Phebe Cramer, Professor of Psychology

Journal of Personality, 67, 535-554 (1999)

The prototype approach was used to assess the presence of personality features associated with borderline, narcissistic, histrionic, and psychopathic personality syndromes in a sample of 91 young adults from the Block and Block (1980) longitudinal study. These personality prototypes were found to be related to the use of denial and projection, and especially to the immature manifestations of those defenses, in ways consistent with theory.

Phebe Cramer, Professor of Psychology and Heather Westergren ’96

Journal of Personality Assessment, 73, 19-30 (1999)

To determine whether social changes in attitudes toward the role of men and women have influenced gender identity measures, 60 male and female college students were assessed using both a Thematic Apperception Test measure (May’s, 1966, Deprivation/Enhancement measure) and a self-report measure (Bem’s, 1974, Sex Role Identity [BSRI]), both of which were developed more than 20 years ago. Although some recent research has found the BSRI to no longer differentiate between men and women (Twenge, 1997; Wilcox & Francis, 1997), this study found significant gender differences for both gender identity measures.

Phebe Cramer, Professor of Psychology

The Psychoanalytic Study of Lives Over Time: Clinical and Research Perspective on Children Who Return to Treatment
in Adulthood, 309-330 (1999)

The chapter discusses the use of defense mechanisms in the analysis of a 10 year old boy, as these are revealed in successive psychotherapy sessions. Developmental changes are noted as the therapy progresses. The chapter points out how empirical investigation supports both theory and clinical observation.

Phebe Cramer, Professor of Psychology

Journal of Personality, 67, 735-760 (1999)

This study considers the contribution of two ego functions—intelligence and defense mechanisms—to ego developmental level. Two independent assessments of ego level were related to IQ and defense mechanism use in a sample of 89 young adults. Whereas IQ and defense were themselves found to be unrelated, both variables predicted ego level: The relation with IQ was linear, whereas the relation with defense was curvilinear. In addition, the relation between defense and ego level varied as a function of IQ level. At low levels of IQ, stronger use of Denial and Projection was associated with higher ego levels. At high IQ levels, strong use of Denial was associated with lower ego levels, whereas moderate use of Projection was associated with higher ego levels.

Phebe Cramer, Professor of Psychology

Encyclopedia of Psychology, American Psychological Association and Oxford University Press. (2000)

A review of the history, rationale and use of the TAT. Clinical and research approaches are discussed. Problems for assessing reliability and validity are considered.

Phebe Cramer, Professor of Psychology

Journal of Research in Personality, 34, 42-72 (2000)

Gender-based differences in the relation between Identity status and personality configurations of 200 male and female college students were studied. For statuses based on commitment (the Achieved and Foreclosed identities), the personality configuration of males and females was more similar than that of males and females in statuses lacking commitment (Moratorium and Diffused). Further, the importance of four personality dimensions that had been hypothesized (Grotevant, 1987) to promote identity development (ego-resilience, openness to experience, self-esteem, and self-monitoring) was found to vary as a function of gender, as did the self-descriptions of males and females in each identity status.

George R. Goethals, Professor of Psychology and
Cynthia McPherson Frantz, University of Massachusetts

Basic and Applied Social Psychology, 21, 167-175 (1999)

Three studies tested the hypotheses that (a) people think college tuition is too high, (b) people know very little about the subsidies colleges provide, and (c) providing people with subsidy information leads them to judge college prices as more reasonable. The results offered qualified support. First people generally thought that public school charges were reasonable, but that private school charges were unreasonable. Second, people were aware of the subsidies provided by public schools, but were often unaware of those provided by private schools. Third, after receiving subsidy information, people increased their reasonableness ratings of private school prices but not public school prices. This was true even when they correctly estimated the private schools’ subsidies. Making subsidy information salient seems to reframe reasonableness judgments.

Myna L. Friedlander, SUNY at Albany, Laurie Heatherington, Professor of Psychology
and Abbe L. Mars ’93

The American Journal of Family Therapy, 28, 133-146 (2000)

Blaming events (N = 25) were identified in seven interviews conducted by prominent theorists who espouse a constructionist or narrative approach to family treatment. Congruent with this perspective, we used conversation analysis (Gale, 1996) and the grounded theory method of constant comparison (Corbin & Strauss, 1990) to identify the therapists’ behaviors and strategies following blame expressed by family members. Results indicated three core categories or themes of therapists’ responses to blame—Ignoring/Diverting, Acknowledging/Challenging, and Reframing—subsuming 17 individual codes (e.g., challenging all-or-none thinking, highlighting neutral information, interrupting, focusing on competence). The most frequent code was focusing on the positive.

Marlene J. Sandstrom, Assistant Professor of Psychology and John D. Coie

Child Development, 70, 955-966 (1999)

This study examines factors associated with the relative stability of peer rejection among elementary school-aged children. Forty-four initially rejected children (some of whom improved their social status while others remained rejected over a 2-year period) were recruited from a larger sociometric sample. Prospective analyses were conducted to determine whether peer nominated aggression and children’s perceptions of their own status in fourth grade were predictive of status improvement by the end of fifth grade. In addition to prospective analyses, initially rejected children and their mothers were invited to participate in a retrospective interview about their social experiences over the past 2 school years. Results of prospective and retrospective analyses suggested that perceived social status, participation in extracurricular activities, locus of control, and parental monitoring were all positively related to status improvement among initially rejected children. Surprisingly, aggressive behavior also was positively related to status improvement among initially rejected boys.

Laura E. Schanberg, Marlene J. Sandstrom, Assistant Professor of Psychology, Kathleen Starr, Karen M. Gill, John C. Lefebvre, Francis J. Keefe, Glenn Affleck, and Howard Tennen

Arthritis Care and Research, 13, 33-41 (2000)

The purpose of this study was 3-fold: 1) to assess the feasibility of a daily diary for use with children with juvenile rheumatic disease (JRD), 2) to describe daily variation in mood, stressful events, and symptoms in children with JRD, and 3) to examine the extent to which daily mood and daily stressful events predict daily symptoms in children with JRD. Twelve children with JRD completed a daily booklet for 7 days. The daily booklet included measures of daily mood, daily stressful events, daily symptoms, and daily function. The children also completed a visual analog scale for pain and the Children’s Depression Inventory. Subjects showed good compliance with scheduled completion and return of the daily diaries. Results indicated that children with JRD showed variability in daily mood, frequency of daily stressful events, and daily symptoms across days. Multilevel fixed effects models showed that more negative daily mood and more daily stressful events significantly predicted increased reports of fatigue, stiffness, and cutting back on daily activities. Negative daily mood also correlated with increases in daily reported pain. These results indicate that daily diary research is both feasible and potentially informative in children with JRD. Our data emphasize the need for further investigation into the role of daily mood and daily stressful events on disease course in JRD.

T. Gilovich, V.H. Medvec, and K. Savitsky, Assistant Professor of Psychology

Journal of Personality and Social Psychology, 78, 211-222 (2000)

This research provides evidence that people overestimate the extent to which their actions and appearance are noted by others, a phenomenon we dub the "spotlight effect." In Studies 1 and 2, participants who were asked to don a t-shirt depicting either a flattering or embarrassing image overestimated the number of observers who would be able to recall what was pictured on the shirt. In Study 3, participants in a group discussion overestimated how prominent their positive and negative utterances were to their fellow discussants. Studies 4 and 5 provide evidence supporting an anchoring-and-adjustment interpretation of the spotlight effect. In particular, people appear to anchor on their own rich phenomenological experience and then adjust—insufficiently—to take into account the perspective of others. The discussion focuses on the manifestations and implications of the spotlight effect across a host of everyday social phenomena.

L.D. Van Boven, J. Kruger, K. Savitsky, Assistant Professor of Psychology, and T. Gilovich

Personality and Social Psychology Bulletin, 26, 619-628 (2000)

Individuals sometimes try to convey different identities to different people simultaneously or to convey certain information to one individual while simultaneously concealing it from another. How successfully can people solve these "multiple audience" problems, and how successfully do they think they can? On the one hand, the research presented here corroborates previous findings that people are rather adept at such tasks. In Study 1, participants who adopted different identities in preliminary interactions with two other participants (acting the part of a studious "nerd" with one and a fun-loving "party animal" with the other) were able to preserve these identities when they interacted subsequently with both individuals at the same time. In Study 2, participants were able to communicate a "secret word" to one audience while simultaneously concealing it from another. Despite their skill at these tasks, however, participants in both studies were overconfident in their abilities, believing that they were better able to solve these multiple audience problems than they actually were.

N. Epley, K. Savitsky, Assistant Professor of Psychology, and R.A. Kachelski

Skeptical Inquirer, 23, 40-45; 58 (1999, Sept./Oct.)

Classic research by cognitive and social psychologists suggests that subliminally presented stimuli can be perceived and can influence individuals’ low-level cognitions. More recent investigations suggest that such stimuli can also affect individuals’ high-level cognitive processes, including attitudes, preferences, judgments, and even their behavior.

T. Gilovich and K. Savitsky, Assistant Professor of Psychology

Current Directions in Psychological Science, 8, 165-168 (1999)

We review a program of research that examines people’s judgments about how they are seen by others. The research indicates that people tend to anchor on their own experience when making such judgments, with the result that their assessments are often egocentrically biased. Our review focuses on two biases in particular, the "spotlight effect," or people’s tendency to overestimate the extent to which their behavior and appearance are noticed and evaluated by others, and the "illusion of transparency," or people’s tendency to overestimate the extent to which their internal emotional states "leak out" and are detectable by others.

Betty Zimmerberg, Sharon H. Rackow ’98 and Karen P. George-Friedman

Pharmacology Biochemistry and Behavior, 64, 717-724 (1999)

The neuroactive steroid allopregnanolone (3a-hydroxy-5a-pregnan-20-one, 3α,5α-THP) has been shown to be involved in the central nervous system's response to stress. This experiment investigated whether response to the neuroactive steroid allopregnanolone, a positive modulator of the GABA_A receptor, would be altered in neonatal or adult rats previously exposed to a chronic stressor - daily maternal separation during the first week of life. Subjects were then tested either as neonates or adults. In neonates, allopregnanolone decreased the number of ultrasonic vocalizations after brief maternal separation. Previously separated subjects vocalized less and were less active than controls, but were not more sensitive to allopregnanolone on either measure. In adulthood, subjects with a prior history of maternal separation had a greater grooming response to a novel environment after a ten minute cold water swim test than non-separated subjects. Allopregnanolone reduced grooming, but, again, there was no difference due to stress history. A significant effect of gender was noted in the adult subjects - females were largely responsible for the effects reported. These results suggest that early maternal separation stress can produce an habituation response in neonates and a long-term sensitization response to later novel stress in adults. However, since the behavioral effects of allopregnanolone were not differentially influenced by this early stress history, the neuroactive steroid/GABA_A receptor complex may not be the major mediator of these early stress sequela. Results indicating that females were more responsive to allopregnanolone than males are discussed in light of previous findings.