ABSTRACTS OF FACULTY PUBLICATIONS
- ASTRONOMY
- Jay M. Pasachoff, Roberta J.M. Olson, and Martha L. Hazen
- Jay M. Pasachoff and Roberta J.M. Olson
- R.B.C. Henry, K.B. Kwitter and J.W. Howard
- M.S. Raljevic, F. Zaratti, and J.M. Pasachoff
- Jay M. Pasachoff, B. Babcock, and K. Reardon 1995
- Jay M. Pasachoff, B. Babcock, J.S. Diaz 98, K. Reardon 92, and R. Nichols-Kiley 98
- CHEMISTRY
- Susan E. Kegley, Assistant Professor of Chemistry, Kristen J. Hansen 91,
and Kevin L. Cunningham
- J. Hodge Markgraf, Professor of Chemistry, Manuel Finkelstein, Part-Time Lecturer in Chemistry, and John R. Cort 91
- J. Hodge Markgraf, Professor of Chemistry, and Daniel E. Patterson 95
- Anne F. Skinner and Mark N. Rudolph96
- June E. Mirecki (University of Delaware), John F. Wehmiller (University of Delaware), Anne F. Skinner
- COMPUTER SCIENCE
- Kim B. Bruce, Professor of Computer Science, Angela Schuett 94, and Robert van Gent 93
- Kim B. Bruce, Professor of Computer Science
- Christopher J. Merz and Michael J. Pazzani, University of California, Irvine
Andrea Danyluk, Assistant Professor of Computer Science
- William Lenhart, Professor of Computer Science, Giuseppe Liotta, Brown University
- GEOLOGY
- B. Gudveig Baarli, Research Associate
- Mary Ann Hirshfeld 96, David P. Dethier, Professor of Geology
- Willard S. Morgan 96, David P. Dethier, Professor of Geology
- David P. Dethier, Professor of Geology, Steven L. Reneau, Los Alamos National Laboratory
- D.P. Dethier, Professor of Geology, Fred Pessl, Jr., R. F. Keuler, U.S. Geological Survey; M.A. Balzarini, University of Washington, D.R. Pevear, Western Washington University
- Rebecca L. Beavers, Duke Univ. Marine Lab, H. Allen Curran, Smith College; William T. Fox, Professor of Geology, Williams College
- Markes E. Johnson, Professor of Geology; W. S. McKerrow, Bernhard Visiting Professor of Geology, 1991
- Markes E. Johnson, Professor of Geology, B. Gudveig Baarli, Research Associate; James H. Scott, Jr. 92
- Markes E. Johnson, Professor of Geology
Jorge Ledesma-Vazquez, Universidad Autonoma de Baja California
Hovey C. Clark 94, Jennifer A. Zwiebel 94
- Rong Jia-yu, Nanjing Inst. of Geology and Palaeontology; Markes E. Johnson, Professor of Geology
- Paul Karabinos, Professor of Geology, et al.
- Paul Karabinos, Professor of Geology
- Paul Karabinos, Professor of Geology, Demian M. Saffer 95
- Demian M. Saffer, University of California Santa Cruz, P Karabinos, Professor of Geology
- S. J. Seaman, University of Massachusetts, R. A. Wobus, Professor of Geology
- MATHEMATICS
- Colin C. Adams, Professor of Mathematics
- Colin Adams, Professor of Mathematics
- Frank Morgan, Professor of Mathematics, Herman Gluck, Dana Mackenzie
- Frank Morgan, Professor of Mathematics
- Frank Morgan, Professor of Mathematics
- Frank Morgan, Professor of Mathematics
- Frank Morgan, Professor of Mathematics
- Frank Morgan, Professor of Mathematics
- Cesar E. Silva, Associate Professor of Mathematics, Philippe Thieullen
- PHYSICS
- G. Sucha, S.R. Bolton, Assistant Professor of Physics, S. Weiss and D.S. Chemla
- Ephraim Fischbach, Dennis E. Krause, Assistant Professor of Physics, Carrick Talmade and Dubravko Tadic
- Dubravko Tadic, Dennis E. Krause, Assistant Professor of Physics, Ephraim Fischbach and Daniel Sudarsky
- Protik K. Majumder, Assistant Professor of Physics, D.M. Meekhof, P.A.Vetter, S.K. Lamoreaux, and E.N. Fortson (University of Washington).
- Protik K. Majumder, Assistant Prof. of Physics
- William K. Wootters, Professor Physics, et al.
- William K. Wootters, Professor of Physics, et al.
- PSYCHOLOGY
- Phebe Cramer, Professor of Psychology
- Phebe Cramer, Professor of Psychology
- Amy Baughcum, 97 and Phebe Cramer, Professor of Psychology
- Steven Fein, Assistant Professor of Psychology
- Betty Zimmerberg, Associate Professor of Psychology, and Grace J. Wang 96
- Betty Zimmerberg, Associate Professor of Psychology, and Kristin Edwards 96.
- Saul M. Kassin, Professor of Psychology, and K. L. Kiechel 94
- Review by Robert D. Kavanaugh, Hales Professor of Psychology
- Kris N. Kirby, Assistant Professor of Psychology; Nino N. Marakovi '94
- Kris N. Kirby, Assistant Professor of Psychology; Nino N. Marakovic 94
- Paul R. Solomon, Professor of Psychology, et al.
- Paul R. Solomon, Professor of Psychology and MaryEllen Groccia
- Paul R. Solomon, Professor of Psychology
- Paul R. Solomon, Professor of Psychology and W. W. Pendlebury
- Paul R. Solomon, Professor of Psychology and William W. Pendlebury, MD
- Paul R. Solomon, Professor of Psychology, Mahri Relin 95, Bridget Kelly 95, MaryEllen Groccia and W. W. Pendlebury
- Paul R. Solomon, Professor of Psychology, Mika Wood 93, MaryEllen Groccia, Bo-Yi Yang, Richard Fanelli and Ronald Mervis
- Anjali Thapar, Assistant Professor of Psychology
- Review by Anjali Thapar, Assistant Professor of Psychology
- Anjali Thapar, Assistant Professor of Psychology, andR. L. Greene
The Earliest Comet Photographs: Usherwood, Bond, and Donati 1858
Journal for the History of Astronomy, 27, 129-145, 1996.
Comets and Meteors in the 18th and 19th Century British Art and
Science
Physics Education (Institute of Physics, Britain), 30, (3),
156-162, 1995.
We describe our project of investigating images of comets and meteors in
British art and science in the period from Newton and Halley to the present.
We explore the early history of astronomy and its intimate relation with
astronomy. We then specialize on the earliest comet photographs, those of
Donati's Comet of 1858, and uncover new information about the English
photographer Usherwood, who scooped the Harvard astronomer Bond in
photographing this bright comet.
A New Look at Carbon Abundances in Planetary Nebulae I. PB6, Hu 2-1, K648
and H4-1
The Astrophysical Journal, 458, 1215-221, 1996.
We introduce and describe a new long-term project whose goal is to employ final
archived IUE spectra to study carbon abundances in a sample of planetary
nebulae representing a broad range in progenitor mass and metallicity. In this
paper we report initial results for PB6, Hu 2-1, K648 and H4-1. Our UV line
strengths for H4-1 are the first such data to be published for this object. By
combining our measured UV line strengths with optical line strengths found in
the literature for each object, we have determined values for the abundance
ratios He/H, O/H, C/O, N/O, and Ne/O using a combined atomic
level-balancing-photoionization model approach. Eventually, the abundances
from this and subsequent studies will be analyzed using a newly improved
stellar evolution code for intermediate-mass stars with the goal of determining
carbon yields for stars of this mass range.
Experiments at Putre for the November 3 Total Solar Eclipse Site of the
International Astronomical Union Expeditions
Revista de la Academia Nacional de Ciencias de Bolivia, No. 69,
pp. 1-10, 1995.
Proceedings of the International Symposium on the Total Solar Eclipse of
November 3, 1994. We describe the suite of experiments carried out by
scientists of 9 different countries at the International Astronomical Union
site at Putre, Chile, for the total solar eclipse of November 3, 1994.
Coronal Heating Studies at the 1994 Total Eclipse
Revista de la Academia Nacional de Ciencias de Bolivia, 69, pp.
18-21, 1995.
We describe the experiments and preliminary results of our search for solar
coronal oscillations at the total solar eclipse of November 3, 1994.
Study of the High-Frequency Coronal-Loop Oscillation Spectrum
at the
1994 Total Solar Eclipse
Bull. Am. Astron. Soc. 27, No. 4, 1995, 1427.
187th Meeting of The Am. Astron. Soc., San Antonio, TX; abstract #101.06
(rescheduled as 42.20). We describe the experiments and preliminary results of
our search for solar coronal oscillations at the total solar eclipse of
November 3, 1994.
Determination of Polychlorinated Biphenyls (PCBs) in River and Bay
Sediments
Journal of Chemical Education, 73, 558-562 (1996)
Polychlorinated biphenyls (PCBs) are a widespread example of organochlorine
substances that were once viewed as "safe" and "non-toxic" whose presence in
the ecosphere is now known to be damaging not only to humans, but also to many
forms of aquatic and terrestrial life. With the arrival of capillary gas
chromatographs into undergraduate chemistry laboratories, it is now possible
for undergraduate students to perform ppb level analysis of environmental
samples containing PCBs. The experiment described in this article was done as
a part of a course in Environmental Science at Williams College, an
interdisciplinary course (chemistry, biology, geology) taken largely by
freshmen and sophomores. There were no college-level prerequisites. The
experiment also was performed on San Francisco Bay sediments by UC Berkeley
students in several pilot sections of the freshman chemistry course. In
addition to introducing the students to some principles of organic chemistry
(distillation, extraction, solubility properties, and chromatography), the goal
of the experiment was to get the students excited about learning more chemistry
by demonstrating how the skills of chemists and the utilization of modern
chemical instrumentation play a key role in efforts to clean up the
environment
Canthine Analogs via Intramolecular Diels-Alder Reactions
Tetrahedron, 52, 461-470 (1996).
Carbocyclic analogs of canthine and canthin-6-one were prepared in three and
four steps, respectively, from indole-3-carboxaldehyde. The key step was an
intramolecular Diels-Alder reaction in refluxing fulfolane.
A Convenient Route to Heteronaphthacenes
Journal of Heterocyclic Chemistry, 33, 109-111 (1996)
Heteronaphthacenes were prepared in two steps from
1,3-dihydrobenzo[c]thiophene 2,2-dioxide via convenient high-temperature
Diels-Alder reactions with benzofuran, benzothiophene, and N-methylindole.
This process represented a marked improvement in the synthesis of these linear
polycyclic aromatic systems.
Dating Flint Artifacts with Electron Spin Resonance: Problems and
Prospects
Archaeological Chemistry V: Organic, Inorganic and Biochemical Analysis;
M. V. Orna (Ed.)
ACS Symposium Series 625 (American Chemical Society 1996).
Electron spin resonance (ESR) dating has been applied to flint artifacts of
recent origin (less than 10,000 years ago). ESR is a dating technique
developed over the last two decades, using the accumulation of radiation damage
as a chronological marker. Using this technique to study archaeological
materials requires demonstrating that the ESR signal clock was reset to zero by
thermal treatment during manufacture of the artifacts. Under probable heating
conditions for these flints, it appears that resetting the signal is
considerably more difficult than has been suggested by previous work.
Comparison of the results with dates for the site obtained by C-14 yields
apparent ages that for the most part are substantially older than the C-14
values, presumably because of insufficient heating in antiquity. However, some
of the flints do fall within the generally accepted age range.
Geochronology of Quaternary Coastal Plain Deposits, Southeastern Virginia,
USA
Journal of Coastal Research, 11(4) 1135-1144 (1995)
Three clusters of amino acid enantiomeric values (or aminozones) are defined
using molluscan fossils from the later Quaternary marine units exposed in Gomez
Pit, in the southeastern Virginia coastal plain. Mean
alloisoleucine/Isoleucine (A/I) values for two aminozones (IIa: 0.17 +/- 0.02;
[Iota][Iota]c: 0.32 +/- 0.02) are superposed, show consistent relation to
lithologic units, and are used to define local alloformations. A third
aminozone (IId: A/I = 0.46 +/- 0.04) cannot be used to define a local
alloformation because all IId mollusks appear to have been reworked into
younger (IIc) lithologic units at the Gomez Pit site. U-Th age estimates on
corals, and electron spin resonance (ESR) age estimates on fossil mollusks are
used to calibrate aminozone IIa. Combined U-Th, ESR, and amino acid
enantiomeric data indicate a Stage 5 (80 to 130 ka) age for aminozone IIa. Age
estimates for older aminozones IIc and IId are calculated using aminozone IIa
calibration applied to kinetic models describing diagenetic racemization.
Using this approach, age range estimates for aminozone IIc (approximately 250
to 400 ka), and aminozone IId (approximately 500 to 800 ka) are proposed.
Aminostratigraphic interpretations are compared with other geomorphic and
stratigraphic studies of the southern Chesapeake Bay region. Deposition of the
"IIa alloformation" is correlative with parts of the Tabb Formation (Sedgfield
Member), or parts of the Norfolk Formation, evolution of the Nassawadox spit
(lower Delmarva Peninsula), and filling of the Eastville paleochannel of the
ancestral Susquehanna River. The "IIc alloformation" is correlative with the
Shirley Formation (on the York-James Peninsula) or Great Bridge Formation.
Aminozone IId (in place elsewhere in the region) is correlative with the
Shirley Formation (on the Rappahannock River), evolution of the Omar-Accomack
spit, and filling of the Exmore paleochannel of the ancestral Susquehanna River.
PolyTOIL: A Type-Safe Polymorphic Object-Oriented Language
ECOOP `95 Proceedings, LNCS 952, Springer-Verlag, pp. 27-51.
PolyTOIL is a new statically-typed polymorphic object-oriented programming
language which is probably type-safe. By separating the definitions of
subtyping and inheritance, providing a name for the type of self, and carefully
defining the type-checking rules, we have obtained a language which is very
expressive while supporting modular type-checking of classes. The matching
relation on types, which is related to F-bounded quantification, is used both
in stating type-checking rules and expressing the bounds on type parameters for
polymorphism. The design of PolyTOIL is based on a careful formal definition
of type-checking rules and semantics. A proof of type safety is obtained with
the aid of a subject reduction theorem.
Progress in Programming Languages
Computing Surveys, Vol. 28, No 1, pp. 245-247.
We survey progress in programming language design over the last 25 years. The
paper discusses new programming language constructs which provide support for
abstract data types, modularity, and polymorphism, among others. It also
discusses progress in imperative, functional, object-oriented, concurrent and
distributed, and logic programming languages.
Tuning Numeric Parameters to Troubleshoot a Telephone-Network Loop
IEEE Expert 11:1, (1996), pp. 44-49.
Nynex MAX is an expert system used to diagnose the local loop of the telephone
network. This expert system analyzes the result of an automated electric test
on a telephone line and, using that and other information, determines the type
of problem. The expert system rules have numeric parameters that give bounds
on electrical measurements that are indicative of each type of problem.
Manually setting these parameter values is a difficult task. The problem is
compounded by the fact that MAX is used at many different sites, and the
peculiarities of each site require that different parameter values be used at
each site. We present a system, called Opti-MAX, that automatically sets the
parameter values by analyzing the decisions made by experts troubleshooting
problems. Opti-MAX can be used to reduce the number of mistakes made by MAX.
Drawing Outerplanar Minimum Weight Triangulations
Information Processing Letters 57 (1996), Pp. 253-260
We consider the problem of characterizing those graphs that can be drawn as
minimum weight triangulations and answer the question for maximal outerplanar
graphs. We provide a complete characterization of minimum weight
triangulations of regular polygons by studying the combinatorial properties of
their dual trees. We exploit this characterization to devise a linear time
(real RAM) algorithm that receives as input a maximal outerplanar graph G and
produces as output a straight-line drawing of G that is a minimum weight
triangulation of the set of points representing the vertices of G.
Orthacean and Strophomenid Brachiopods From the Lower Silurian
of the
Central Oslo Region
Fossils and Strata, 39, 1-93 (1995)
Brachiopods of the Superfamily Orthacea and the Order Strophomenida from the
Llandovery of the Oslo-Asker District of Norway are described taxonomically.
The fauna comprises 41 species belonging to 29 genera. Among these, 3
genera, 10 species, and 1 subspecies are new. They include the genera
Orthokoptis, Crassitestella, and Eocymostrophia, the species Orthokoptis
idunnae, Eridorthis vidari, Plectorthis, Skeidioides worsleyi, Skenidioides
hymiri, Dactylogonia dejecta, Eostropheodonta delicata, Mesopholidostrophia
sifae, Eocymostrophia balderi, Fardenia oblectator and Eoplectodonta
transversalis (Wahlenberg, 1818) jongensis. Parts of the brachiopod fauna
occurring across the Ordovician-Silurian boundary are unique in representing
relict Ordovician taxa. They are related to relatively rare offshore faunas
preserved in uppermost Ordovician strata; they survived into the Silurian in
the tectonically active, deeper-water environments found in the intracratonic
basin of the Oslo Region. The rest of the Llandovery fauna shows very close
ties with the faunas and faunal structure of the Welsh Basin, suggesting
minimal geographic separation between Baltica and Avalonia. Similarities at
species level between the Gornyj Altaj and the Norwegian-Welsh fauna also
suggest that the two areas were situated in the same climatic zone, contrary
to some recent paleogeographic reconstructions. A rare fauna of the Southern
Mid-continent of Laurentia lived in similar facies as the Norwegian-Welsh
fauna and shows strong resemblances on a generic level. Except for some
eurytopic species, however, many of the species are different, indicating that
Silurian barriers existed between these locations.
Inside a Latest Pleistocene Glaciomarine Fan, Northern Puget Lowland,
Washington
Geological Society of America Abstracts with Programs, 28 (3), 64
(1995)
Mapping of surficial deposits, well logs, and marine seismic reflection studies
demonstrate that the S. tip of San Juan Is. (Cattle Point) and adjacent
submerged Salmon Bank represent a latest Pleistocene (Fraser glaciation)
ice-contact glaciomarine fan. San Juan Is. lies in NW Washington in an
extensive trough that was filled with Cordilleran ice during the Fraser
glaciation. Since deglaciation, erosion resulting from glacioisostatic
rebound, eustatic sea level rise, and tectonic uplift has reshaped some glacial
depositional and erosional features. During deglaciation of NW Washington
after about 14.0 14C yrs B.P. (14.0 ka), the Puget and San Juan
Lobes of the Cordilleran ice sheet calved back rapidly, pausing periodically on
topographic highs. Retreating ice probably grounded near Cattle Point before
about 13.2 ka. We interpret the > 2 km wide, 100-m thick deposit of sand
and gravel, named the Cattle Point moraine by J. Harlen Bretz, as an
ice-contact submarine fan. Mapping of sea cliffs along the margins of Cattle
Point shows that 600 meter-long W. and S. dipping beds of
interbedded sands and medium gravels rest on bedded medium sand. Channels
eroded > 10 m into the sand contain boulders up to 35 cm in diameter.
Paleocurrent measurements based on pebble imbrication indicate flow distributed
symmetrically within 50o of 180o. Two 500 m-wide
channels filled with glaciomarine diamict were eroded into the submarine fan,
presumably as the ice lobe retreated N from Cattle Point. Seismic reflection
profiling of Salmon Bank shows that >75 meters of flat lying or gently S
dipping sediment overlies bedrock or glacial till, implying that this adjacent,
7 km-long feature is genetically related to the submarine fan at Cattle Point.
Stratigraphic relationships, sedimentary structures, and paleoflow directions
provide information about the depositional processes of this submarine fan, and
allow a better understanding of the retreating Cordilleran ice.
Terrestrial and Marine Evidence for Changing Ice Regime During Latest
Pleistocene Ice Recession, Northern Puget Lowland, Washington
Geological Society of America Abstracts with Programs, 28 (3),
84 (1995)
Deposits and landforms on the south end of Lopez Island and beneath adjacent
marine water in the Puget Lowland, Washington record retreat of Cordilleran
ice, glaciomarine and marine deposition between 13.2 and 12.4 14 C
yrs B.P. (ka), and rapid isostatic rebound. We mapped terrestrial landforms,
measured ice flow direction, compiled well-logs and collected 16 km of shallow
seismic reflection lines over Lawson Reef, an arcuate submarine bank 4.5 km
long and 45-80 m thick, located SE of Lopez Is. The extensive exposures of
glaciomarine fans and diamicts on Lopez, throughout the San Juan Is., and on
the sea floor, imply widespread sedimentation from grounded and floating ice
during retreat. Striae, grooves and troughs oriented from 200o to
250o record reorientation of flow as ice thinned and evolved a
lobate margin.
Marine seismic surveys of Lawson Reef demonstrate that it is a morainal
embankment composed mainly of submarine outwash. Crossbedding and channel-fill
features record paleoflow to the south. The morphology and composition of
Lawson Reef and regional relations suggest that it formed at the margin of a
thinning lobe of Cordilleran ice during a brief stillstand.
On S. Lopez Is., glacioisostatic rebound raised shallow subtidal sediment
containing in-situ Saxidomis gigantea > 130 m, probably soon after about
12.5 ka. The terrestrial and marine evidence suggests that retreat of
Cordilleran ice from NW Washington and Laurentide ice from coastal Maine were
similar in chronology, styles of sedimentation and magnitude of glacioisostatic
rebound.
Quaternary History of the Western Espanola Basin, New Mexico
New Mexico Geological Society, Guidebook, 46, 289-298 (1996)
Quaternary deposits and landforms are exposed widely in the Espanola Basin,
where base level has fallen >150 m since early Pleistocene time and
drainages have eroded weak Cenozoic rocks, stranding ancestral piedmont and
axial channel deposits beneath terraces that flank the Rio Grande valley.
Extended periods of high flow on drainages that carried pluvial and glacial
runoff probably produced middle and late Quaternary incision. The Bandelier
Tuff (1.6 and 1.2 Ma), Lava Creek B ash (0.62 Ma) and the El Cajete pumice
(50-60,000 ybp) provide local age control, supplemented by ages estimated from
amino-acid ratios in gastropods and by 14C ages. The Pajarito,
Rendija Canyon and Guaje Mountain faults displace Pleistocene deposits; the
latter faults were probably active in the Holocene. The NE-trending Embudo
fault zone has been the northern structural margin of the Espanola Basin since
middle Miocene time, but it is difficult to demonstrate Quaternary slip along
the zone. Quaternary fluvial deposits consist of axial-channel gravels and
thin overbank deposits covered by coarse sand and gravel delivered by ancestral
alluvial fans. Sequences of lithologically similar deposits are preserved at
heights from more than 170 m to 15 m above the modern floodplain between
Abiquiu and Otowi Bridge. These sequences suggest that alluvial fans expand
across the Rio Grande floodplain during transitions from pluvial to
interpluvial climate and that deposits are preserved when the river cuts down
during the next pluvial period. Holocene cut and fill sequences are preserved
along some tributaries to the Rio Grande, but their climatic significance is
uncertain. Incision along the Rio Grande in upper White Rock Canyon generated
massive slumps beginning in middle Pleistocene time as the river cut through
weak rocks of the Santa Fe Group, the Puye Formation and Pliocene lacustrine
deposits. Reactivation of toe areas of some slumps dammed the Rio Grande at
>43 ka and at least four times between 18 and 12 ka, producing lakes as deep
as 60 m. Landslide motion and lake age in White Rock Canyon coincide with the
glacial maximum and final pluvial pulses of the latest Pleistocene, suggesting
that climate change destabilized older slumps through toe incision or by
greater pore pressures from increased groundwater recharge. The Rio Grande
flowed at its modern grade before about 12 ka.
Late Wisconsinan Glaciomarine Deposition and Isostatic Rebound,
Northern
Puget Lowland, Washington
Geological Society of America Bulletin, 107, 1288-1303 (1995)
The distribution and age of glaciomarine and marine sediment in the northern
Puget Lowland, Washington, demonstrates that rapid retreat of continental ice,
the Everson marine incursion, and high rates of isostatic rebound occurred
between about 13,600 and 11,300 14C yr B.P. (11.3 ka). Glaciomarine
and marine deposits are thickest in zones where retreating ice lobes grounded,
in the NE Puget Lowland, and near large drainages. Glaciomarine sediment was
deposited mainly from: (1) submarine outwash in ice-proximal zones; (2) turbid
underflows, dispersed meltwater, icebergs, and resedimentation in transitional
zones; and (3) dispersed meltwater and currents in ice-distal zones. Marine,
estuarine and emergence (intertidal and beach) facies accumulated in areas more
than 10 km from ice margins, particularly near major rivers. Molluscan and
foraminiferal assemblages in the glaciomarine and marine deposits indicate that
turbid, cool, brackish water covered much of the Puget Lowland during the
Everson interval. Water was generally shallower (<30 m) in the southern
part of the area and deeper (15-60 m) to the north. Mineralogy and geochemical
properties such as boron or sodium content of the gravel-free fraction do not
clearly distinguish glaciomarine and marine deposits from terrestrial deposits.
Isostatic rebound rapidly lifted the glaciomarine and marine deposits through
sea level between about 13.5 and 11.3 ka. The present altitudes of
radiocarbon-dated shell and the marine limit show that initial rates of
isostatic rebound exceeded 10 cm yr-1 in the northern Puget
Lowland, but dropped to 2 cm yr-1 before 11 ka. The uplift gradient
is about 0.6 m km-1 to the north and steepens locally to at least
l.3 m km-1. The pattern of emergence in the northern Puget Lowland
is anomalous locally, perhaps as a result of complex isostatic effects near the
glacier margin, rapid rise of sea level or tectonic deformation.
Long-Term, Storm-Dominated Sediment Dynamics on East Beach
and Sandy
Point, San Salvador Island, Bahamas
Seventh Symposium on the Geology of the Bahamas, 1-15 (1995)
Beginning in June, 1990, the carbonate sand strandlines at East Beach
(windward) and Sandy Point (leeward) on San Salvador Island have been monitored
biannually for morphologic and sedimentologic change by students and faculty of
the Keck Geology Consortium (Brill et al., 1993; Loizeaux et al., 1993). The
present study builds on findings from these two earlier reports and focuses on
the monitoring period of January, 1992, to January, 1993.
East Beach is located on the windward, northeastern coast of San Salvador.
Surveys of 9 transect lines along 1 km of beach were combined with data from 6
offshore profiles to evaluate changes from January, 1992, to January, 1993.
Between June, 1992, and January, 1993, net erosion of 4000 m3 of
sediment occurred along the foreshore with deposition in offshore areas and
along the dune line. Brill et al. (1993) also documented net erosion of
sediment during the July to January period in previous years, principally from
the effects of late fall and winter wave energy. At East Beach, sediment is
restored to the foreshore during the January to July period, resulting in a
progradational beach. This seasonal pattern of cross-shore sediment migration
has been the norm for East Beach over the four-year monitoring period.
Located along the southwestern corner of San Salvador, Sandy Point is a highly
dynamic, partially leeward strandline. At Sandy Point, 2.4 km of beach were
surveyed along 17 transects twice in June, 1992, and again in January, 1993.
The two June data sets clearly document the effects of a strong southwesterly
storm which resulted in significant deposition and movement of sand lobes at
the point of Sandy Point. Offshore sediment characteristics at the northern
end of the study area confirm storm-related longshore sediment migration
patterns observed along the foreshore of Sandy Point. Sediments transported to
the north from around Sandy Point and deposited offshore are very well sorted,
fine sands, whereas sheltered Grotto Bay sediments are another distinct
sediment population of moderately sorted, coarse sands which are transported
south during winter northwesterly storms. Sediment distribution along both
Sandy Point and East Beach is controlled by sediment exchange between the
nearshore and beach environments as dictated by spatial and temporal patterns
of storms.
The Sutton Stone: An Early Jurassic Rocky Shore Deposit in South
Wales
Palaeontology, 38 (3), 529-541 (1995)
The unconformity between Jurassic and Carboniferous carbonates at Southerndown,
near Ogmore-by-Sea, Mid-Glamorgan, represents an ancient rocky shoreline which
has had a long history of study. Henry De la Beche discussed the ecological
details of the unconformity surface, but subsequent debates focused more on the
age and depositional setting of the basal Jurassic conglomerate known as the
Sutton Stone. Our contribution returns to the theme of faunal development on
the unconformity surface. The Jurassic corals, Allocoeniopsis gibbosa and
Heterastraea sp., occur as encrusters of the Carboniferous substrate on a tidal
abrasion platform. Serpulid-worm colonies may be observed in life position
above the stepped unconformity, but not attached to it. These and other
features of a physical and biological nature suggest sporadic preservation in
rapidly changing ecological settings during an Early Jurassic marine
transgression.
Colonization and Reef Growth on a Late Pleistocene Rocky Shore
and
Abrasion Platform in Western Australia
Lethaia, 28, 85-98 (1995)
A low, rocky shoreline and attached abrasion platform of Late Pleistocene age
are marked by a sharp disconformity within the Tamala Limestone Formation,
exposed at Cape Burney facing the Indian Ocean near Geraldton, Western
Australia. Colonization by an intertidal to shallow subtidal biota dominated
by encrusting coralline red algae, oysters, and tube-dwelling worms occurs on
a sandstone surface with a channeled topographic relief of 20-30 cm. The
encrusting cup coral Rhizotrochus tuberculatus also is present, and this report
details what is probably the first fossil occurrence of that species. The
ancient rocky shore above this level retains trace fossils characteristic of a
boring barnacle, probably belonging to Lithotrya. Herein named the Cape Burney
sandstone, the distinctive unit on which the disconformity sits is assigned
member status within the Tamala Limestone. Shell beds with a diversity of 35
species, dominated in volume by robust gastropods such as Turbo intercostalis
and T. torquatus, thinly drape portions of the disconformity surface.
Succeeding the shell drapes is a reef limestone with a maximum thickness of
more than 2 m. The limestone is a massive accumulation of collapsed but
otherwise mostly undisturbed coral fronds belonging primarily to a robust
species of Acropora. Herein named the Bootenall limestone, this unit is
assigned member status within the Tamala Limestone. Based on an analysis of
electron spin resonance (ESR) from Acropora samples, the fringing reef
developed between 120 ka and 132 ka, in the terminal stage of coastal
transgression during the last interglacial period (Oxygen Isotope Substage
5e).
Coastal Evolution of Late Cretaceous and Pleistocene Rocky Shores:
Pacific Rim of Northern Baja California, Mexico
Geological Society of America Bulletin, 108, 708-721 (1996)
Cretaceous on Cretaceous and Pleistocene on Cretaceous unconformities are
mapped throughout a 45 km2 field area surrounding the
village of Erendira on the Pacific coast of northern Baja California, Mexico.
The unconformities represent a late Pleistocene rocky shore (120,000-130,000
ka) directly superimposed on a Campanian-early Maastrichtian rocky shore
(77-70 Ma). Superb exposure and preservation of coastal features allow for
precise paleogeographic restorations. Physical analysis includes a comparison
of rocky-shore composition, configuration, and overall length. Paleoecological
analysis permits the recognition and comparison of preferred wave directions.
High-intensity, windward biotas during the Late Cretaceous included
rock-encrusting rudists and coralline red algae, while low-intensity, leeward
biotas were characterized by rock-encrusting oysters, scleractinian corals,
and bryozoans. During the Pleistocene, the open coast was exploited by the
byssate bivalve Mythus and boring bivalves including Petricola and Penitella,
while more protected settings were dominated by the gastropods Olivella and
Saxidomus. Amino-acid analysis of Saxidomus nuttalli yielded an age estimate
consistent with the last interglacial epoch (oxygen isotope stage 5e). Wave
impact was oblique to the paleoshore during the late Pleistocene; onshore winds
were generated from the west. In contrast, wave movement was generated from
the east to southeast and parallel to shore during the Late Cretaceous. Field
data are integrated with paleogeographic reconstructions and predictive models,
including computer models for local and global oceanography. Where different
paleogeographics and oceanographic models conflict, field mapping of this sort
adds a much needed element of ground truth.
A Stepped Karst Unconformity as an Early Silurian Rocky Shoreline
in
Guizhou Province (South China)
Palaeogeography, Palaeoclimatology, Palaeoecology, 121, 115-129
(1996)
Where succeeded by marine strata, karst unconformities signify a former rocky
coastline. Such relationships may help sort out relative sea-level changes and
aspects of local geography controlling facies distribution. An exceptional
example of an early Silurian karst shore is well exposed near the village of
Wudang in central Guizhou Province, near the capital city of Guiyang in South
China. Here the Lower Silurian Kaochaitien Formation oversteps 63 m of
paleotopographic relief in limestones belonging to the Llanvirn Guniutan
Formation and Caradoc to early Ashgill Huanghuachong Formation (Ordovician).
The corresponding rise in sea level took place coeval with tectonic uplift, as
confirmed by a regionally diachronous relationship in the Ordovician-Silurian
boundary across a 250 km track from central to northern Guizhou Province. The
change in sea level also fits with a global rise of sea level in late Aeronian
(later Llandovery, early Silurian) time. Borings of the ichnofossil,
Trypanites, are reported from the karst surface of the Huanghuachong Formation
and Silurian strata fill sink holes in this unit over 5 m deep. The Silurian
karst shoreline near Wudang is integrated with other regional data to construct
a paleogeographic map covering the northern half of Guizhou Province.
The Taconian Orogeny in New England: Collision Between Laurentia
and
the Shelbourne Falls Arc
Geological Society of America Abstracts with Programs, 24, 70
(1996)
New U-Pb zircon analyses on felsic gneisses of the Collinsville Fm. (CF) from
the Shelburne Falls dome, Mass. and the Barnard Volcanic Member of the
Mississquoi Fm. (BVM) from the type locality in Barnard, Vt. give ages of 473
+ 2 Ma and 471 + 4 Ma, respectively. In addition, the weighted
average of 206Pb/238U ages from 13 grains, determined by
ion microprobe (SHRIMP), is 462 + 6 Ma for a trondhjemite from the BVM
from South Newfane, Vt. These new ages combined with previously reported U-Pb
and evaporation zircon ages on seven samples of the BVM, the CF, and the
Hallockville Pond Gneiss (HPG) from Plainfield, Mass. indicate that these rocks
formed approximately 20 to 30 my. before lithologically similar rocks in the
Bronson Hill arc (454 to 442 Ma; Tucker and Robinson, 1990). Dated felsic
rocks from the BVM, the CF, and the HPG plot in the volcanic arc fields in
granite discrimination diagrams such as Ta vs. Yb and Nb vs. Y. They are light
REE enriched with La ranging from 20 to 80 times chondrite and have negative Eu
anomalies indicating plagioclase fractionation. The Shelburne Falls arc,
preserved in eastern Vt. and western Mass. by the BVM, CF, and HPG, probably
formed as a magmatic arc on a continental sliver above an east-dipping
subduction zone by approximately 480 to 470 Ma. This arc collided with
Laurentia during the Taconian orogeny. The Bronson Hill arc most likely formed
above a west-dipping subduction zone near the Laurentian margin after the
Taconian orogeny. The younger Bronson Hill arc magmatism was followed by Late
Ordovician and Silurian back-arc rifting recorded by bimodal volcanic rocks
located in the region between the Bronson Hill and Shelburne Falls arcs.
Fault Geometry and Kinematics in the Taconian Thrust Belt
of New England
and New York
Geological Society of America Abstracts with Programs, 24, 70
(1996)
Attempted subduction of the Laurentian margin began before 470 to 465 Ma based
on 40Ar/39Ar cooling ages from continental margin rocks
reported by Laird et al. (1984) and Sutter et al. (1985). As the Laurentian
margin approached the east-dipping subduction zone, imbricate thrusts developed
first in the distal rise deposits above transitional crust, which was at least
partly subducted. Thrusts propagated westward from the rise deposits into the
slope deposits located above continental crust. As plate convergence
continued, buoyancy forces resisted subduction of continental crust and
thrusting propagated downward into Grenvillian basement and unconformably
overlying slope and shelf deposits. Duplexes composed of these rocks such as
the Berkshire and Green Mountain massifs formed near the shelf-slope
transition. Motion within these duplexes displaced the overlying classic
Taconic allochthons further westward and because the duplexes developed as
antiformal stacks, erosion above them isolated the allochthons as klippen.
Thrusting east of the Rowe belt in fore-arc rocks (Moretown Fm.) and arc rocks
(Collinsville and Hawley Fms. in Mass., Barnard Volcanic Member in Vt.)
probably occurred relatively late in the orogeny when shortening within the
continental margin could no longer keep pace with the rate of plate
convergence. Thrusting at the Moretown Fm.-Rowe Schist contact ended before
447 + 3 Ma based on an evaporation zircon age from the Middlefield
Granite in Mass. which crosscuts the thrust contact (Karabinos and Williamson,
1994). Evidence for reactivation of imbricate thrusts during the Taconian
orogeny is best preserved by fault-bounded slivers of carbonate and flysch
deposits located between thrust sheets of Taconic sequence rocks. The slivers
formed when an imbricate stack of Taconic sequence rocks overrode the carbonate
shelf and overlying flysch deposits and large portions of the foot-wall became
accreted to the hanging-wall. The accreted slivers were faulted into position
as motion existing imbricate splays accompanied movement on the basal sole
thrust.
Airy Stress Functions to Quantify Crustal Stress Field Perturbations Near
Active Faults
EOS, 76, F555 (1995)
The observation that principal stresses are nearly parallel and perpendicular
to the San Andreas fault in California (Zoback et al., 1987; Mount and Suppe,
1987) indicates that faults with low shear strength can perturb crustal stress
fields. Such perturbations can be quantified using three dimensional Airy
stress functions. Because heat flow measurements constrain shear stresses
along weak fault segments (e.g., Lachenbruch and Sass, 1980), it is natural to
begin by constructing a Fourier series to describe the shear stresses. Then
appropriate expressions for normal stresses parallel and perpendicular to the
fault are derived. Perturbations decay exponentially with distance from the
fault. If one of the principal stresses is vertical and due solely to
lithostatic load and if the fault plane is vertical, then a single Airy stress
function is sufficient to quantify the stress field.
This method yields predicted stress trajectories that are consistent with
stress orientations inferred from field observations. The distance
perpendicular to the fault over which stress perturbations are significant is
proportional to the along-strike length of the weak fault zone. The magnitude
of the stress perturbations increases as shear strength of the weak zone
decreases. The region between offset weak segments approximates compressional
bends. The predicted location and orientation of ancillary faults depend on
the tectonic stress gradient and the nature of the stress concentrations at the
ends of weak segments. Ancillary faults should be especially common in the
region between two offset weak segments. It may be possible to use this model
along with geological constraints to determine very accurately stresses along
major faults such as the San Andreas.
Stress Perturbations Near Active Strike-Slip Faults:
Applications to
the San Andreas Fault System, California
EOS, 76, F555 (1995)
Low shear strength along weak segments of the San Andreas fault induces
significant perturbations in the crustal stress field (Zoback et al., 1987;
Mount and Suppe, 1987). Using an Airy stress function which combines the
effects of lithostatic and tectonic stresses with fault induced perturbations,
we modeled the stress field near the San Andreas fault. Straight fault
segments are treated as weak zones with low shear strength; fault bends are
treated as regions between offset weak zones. We used the depth and dip of
thrust earthquake focal mechanisms to estimate the tectonic stresses as a
function of depth. This empirical approach indicates a linear gradient and
takes into account the effects of fluid pressure. We inferred that the minimum
and intermediate principal stresses are nearly equal because both ancillary
strike-slip and thrust faults are common in the vicinity of the San Andreas
fault.
Our model predicts stress trajectories which are consistent with field
measurements near the San Andreas fault. Stress concentrations caused by slip
on weak fault segments occur in adjacent locked zones, so that ancillary
strike-slip and thrust faults are most likely near the tips of weak segments
and especially between offset weak segments. In addition, thrusting is confined
to depths below 2-4 km, consistent with the presence of blind thrusts near
portions of the San Andreas fault. Predicted ancillary fault locations and
orientations in compressional fault bends are consistent with those of most
major secondary faults in the big bend region of the San Andreas system,
including the Nacimiento, Death Valley, Mission Creek, San Jacinto, and
Elsinore faults.
The Cranberry Island Series of Coastal Maine:
Bimodal Volcanism on
Pre-Acadian Avalon
Abstracts Volume, XXI General Assembly, International Union of Geodesy and
Geophysics, A439 (1995)
The Cranberry Island series (CIS) consists of shallow intrusions overlain by at
least 2.6 km of volcanic breccias, tuffs, and lava flows. The succession is
divided into three members, including, from bottom to top, 1) poorly-exposed
felsite dikes and small heterogeneous intrusions which possibly represent magma
which filled ring fractures during the pre-eruption stage of magmatism; 2)
dominantly felsic pyroclastic rocks which host inclusions interpreted as
multicompositional pods of magma, erupted with the felsic ash and transported
and deformed in ash flows, and 3) basaltic tuffs and lava flows, produced by
an explosive, possibly phreatomagmatic, eruption followed by effusive
extrusion of basalt. The granitic to gabbroic Cadillac Mountain intrusive
complex (Wiebe, 1994), due north of the exposure of the CIS, is likely to be
the plutonic complex from which the CIS erupted, on the basis of the
chronological and compositional similarity of the volcanic and plutonic
rocks.
Too much of the CIS and its borders are under ocean water to identify evidence
relating the rocks to a caldera structure. However, the volume of material
erupted (approx. 120 km3 to approx. 1700 km3, depending
on estimates of outcrop extent), is compatible with caldera-style eruptions,
and the mafic over felsic stratigraphy of the complex is typical of
caldera-related successions in settings of continental crustal extension.
The pre-Acadian age of the CIS indicates that magmatism and volcanism took
place on Avalon prior to the time of its collision with North America during
the Acadian orogeny.
Unknotting Tunnels in Hyperbolic 3-Manifolds
Math Ann., 302, 177-195 (1995)
In this paper, we examine the relationship between the unknotting tunnels of a
hyperbolic 3-manifold and the hyperbolic structure on that manifold. In
particular, we begin by proving that the maximal cusp volume of a 1-cusped
hyperbolic 3-manifold with tunnel number greater than one is at least
3[radical]3/4. This implies that the volume of the entire manifold is at least
3v0/2, where v0 = 1.01494... . Several interesting corollaries of a purely
topological nature follow. These results point toward a new invariant for any
compact 3-manifold, which is the least volume of any hyperbolic knot complement
within it. We investigate this "parent volume", determining the manifold of
least parent volume and the manifold with boundary of least parent volume. We
also give necessary conditions for a vertical geodesic to be an unknotting
tunnel and use this to classify all of the isotopy classes of unknotting
tunnels for the Whitehead link and a few other links. Moreover, in addition to
other applications, we obtain a universal upper bound of ln(4) on the length of
the shortest representative in the isotopy class of an unknotting tunnel for a
2-cusped hyperbolic 3-manifold. Finally, we begin to delineate some
restrictions on the hyperbolic structure of a tunnel number one hyperbolic
3-manifold.
Hyperbolic 3-Manifolds with Two Generators
Communications in Analysis and Geometry, Vol. 4, No. 2, 181-206, 1996.
It is shown that if there are two parabolic elements that generate a
non-elementary Kleinian group that is not free, then there is a universal upper
bound of two on the "length" of each of those parabolics, length being measured
in a canonical choice of cusp boundaries. Moreover, there is a universal upper
bound of ln(4) on the "distance" between those parabolics, where the distance
between them is the distance between a pair of horoballs corresponding to the
canonical cusps. A variety of results are proved with these, the most
interesting of which is: An orientable finite volume hyperbolic 3-manifold that
has fundamental group generated by two parabolic isometries must be a 2-bridge
knot or link complement.
Volume-Minimizing Cycles in Grassmann Manifolds
Duke Math. J., 79: 335-404 (1995)
Least-volume representatives are found for example for every real homology
class in H4 of the Grassmannian G(4,R8) of oriented
4-planes in R8, which has rank 3. The surfaces are
calibrated by quaternionic and Pontryagin forms. For
H4G(3,R7), in one Pontryagin homology class there
are no calibrated surfaces, and therefore infinitely many associated minimal
surfaces. The proofs rely on comass estimates for the relevant calibrations.
Strict Calibrations
Matemática Contemporánea, 9: 139-152 (1995)
Strict calibrations have comass strictly less than one off the calibrated
surface S and hence prove S uniquely area-minimizing. Ordinary and strict
calibrations, with the usual closure condition relaxed, can prove
constant-mean-curvature surfaces area-minimizing for fixed volume constraints.
Strict calibrations are sufficiently adaptable for prove minimizing properties
of certain triple junctions of constant-mean-curvature surfaces.
The Double Bubble Conjecture
FOCUS (1995)
A report on the recent computer proof by Hass and Schlafly of the Double Bubble
Conjecture on the least-area way to enclose and separate two regions of equal
volumes.
Calculus Lite
A K Peters, (1995)
This lean text covers single-variable calculus in 250 pages by: (1) getting
right to the point, and stopping there, and (2) introducing some standard
preliminary topics, such as trigonometry and limits, by using them in the
calculus.
For the Minimal Surface Equation, the Set of Solvable Boundary Values
Need Not be Convex
Bull. Aus. Math. Soc., 53: 369-372 (1996)
One might think that if the minimal surface equation had a solution on a smooth
domain D
Rn with boundary values [phi], it would have a solution with
boundary values t[phi] for all 0 <= t <= 1. We give a counterexample in
R2.
What is a Surface?
Amer. Math. Monthly, 369-376 (May 1996)
A search for a good definition of surface leads to the rectifiable currents of
geometric measure theory, with interesting advantages and disadvantages.
A Skew Product Entropy for Nonsingular Transformations
Journal of London Mathematical Society, Vol. 2, No. 52, 497-516 (1995)
We define a skew product entropy for conservative nonsingular transformation,
show that it takes values in {0,
*} and use it to distinguish two classes on
nonsingular transformations. Binary and ternary type IIIl odometers have zero
skew product entropy, while nonsingular K-automorphisms have infinite skew
product entropy.
Period Doubling and Quasi-periodicity in Additive-pulse Mode Locked
Lasers
Optics Letters, Vol. 20, No. 17, 1794-1796, September 1995
We have observed period doubling and quasi-periodicity in an additive pulse
mode locked F-center laser. Experiments show that period doubling is often
present even though standard diagnostics such as pulse autocorrelation and
spectra show no indication of it. Numerical simulations show that the period
doubling is associated with strong pulse reshaping.
Higher-order Weak Interactions and the Equivalence Principle
Physical Review D, 52, 5417-5427, 1995.
We consider the possibility that gravity may couple anomalously to the weak
interaction and thereby lead to a violation of the weak equivalence principle.
It is shown that the contribution to the energy of a nucleus arising from
neutrino-antineutrino exchange can be calculated rigorously, and may be the
dominant contribution from higher-order weak interactions. At the level of
sensitivity that could be reached in the proposed STEP (Satellite Test of the
Equivalence Principle) experiment, detection of an acceleration difference
between the test masses could lead to new constraints on the coupling of
gravity to neutrinos, and to higher-order weak interactions.
Time Dependent Perturbation Theory
and the Zel'dovich Electric Dipole
Moment in Atoms
Fizika B, 4, 259-272, 1995.
We use time dependent perturbation theory to investigate the Zel'dovich
electric dipole moment. We show that the vanishing Stark shift and
non-vanishing torque arise from different time dependencies used in their
calculation.
Optical Rotation Technique used for a High-Precision Measurement
of
Parity Nonconservation in Atomic Lead
Phys. Rev. A52, 1895 (1995)
We have measured the parity nonconserving optical rotation near the 1.279 -um
3P0->3P1 magnetic dipole
absorption line in atomic lead vapor. We measure the quantity R
[equivalence]Im(EPNC/M), where M is the
magnetic-dipole amplitude of the absorption line and EPNC is
the electric-dipole amplitude coupled into the same line by the PNC interaction
within the lead atom. We find R to be (-9.86+/-0.04+/-0.11) x
10-8, where the first error is statistical and the second is
systematic. The errors are caused by line-shape uncertainties and calibration
error. Our value is consistent with the atomic PNC calculations for lead,
which give R = (-10.7+/-0.8) x 10-8 for the standard
electroweak model with sin2[theta]W = 0.23 and no
electroweak radiative corrections. Including radiative corrections yields the
value S = 3+/-8 for the isospin conserving electroweak parameter, with
difficulties in the atomic theory of lead presently limiting the extent to
which our result tests the standard model. By searching for a difference in
R for the two hyperfine components of the 207Pb, we find the
amplitude of the nuclear spin-dependent PNC rotation to be less than 2 x
10-2 of the nuclear spin-independent rotation.
High-Precision Measurements of Atomic Parity Nonconservation in Lead and
Thallium
5th Conference on the Intersections Between Particle and Nuclear
Physics; AIP Conference Proceedings 338, ed. S.J. Seestrom (1995)
Atomic parity nonconservation experiments in a number of elements have now
achieved the level of precision necessary for significant tests of the physics
of and beyond the standard model of electroweak interactions. In our
laboratory, parity nonconserving (PNC) optical rotation has been measured in
both atomic lead and thallium at the 1% level of precision. The prospect of
equally precise calculations of thallium atomic structure make this element an
excellent candidate for a new low-energy test of electroweak physics. By
studying hyperfine differences in thallium PNC, this experiment is also
sensitive to nuclear spin-dependent (anapole moment) effects at the level
predicted by several models.
Purification of Noisy Entanglement and Faithful Teleportation via Noisy
Channels
Physical Review Letters, 76, 722, 1996.
Two separated observers, by applying local operations to a supply of
not-too-impure entangled states (e.g., singlets shared through a noisy
channel), can prepare a smaller number of entangled pairs of arbitrarily high
purity (e.g. near-perfect singlets). These can then be used to faithfully
teleport unknown information through a noisy channel. We give upper and lower
bounds on the yield D(M) of pure singlets (|[Psi]->)
distillable from mixed states M, showing D (M) > 0 if
<[psi]-|M|[psi]-> >1/2.
Limitation on the Amount of Accessible Information in a Quantum
Channel
Physical Review Letters, 76, 3452, 1996.
We prove a new result limiting the amount of accessible information in a
quantum channel. This generalizes Kholevo's theorem and implies it as a simple
corollary. Our proof uses the strong subadditivity of the von Neumann entropy
functional S([rho]) and a specific physical analysis of the measurement
process. The result presented here has application in information obtained
from "weak" measurements, such as those sometimes considered in quantum
cryptography.
Story-Telling, Narrative and the Thematic Apperception Test
New York: Guilford Press (1996)
The Thematic Apperception Test (TAT), a systematic approach to storytelling,
provides clinicians with an effective method for investigating those original
and highly personal themes that constitute the unique personality of each
individual. This book illuminates the meaning of narratives and explores their
clinical implications by integrating a variety of interpretive approaches to
the TAT that are informed by psychodynamic theory and empirical research.
Applying contemporary ideas about narrative materials, such as biography or
interviews, for clinical or research purposes. It also serves as a text or
supplemental reading for a range of advanced courses in clinical psychology,
research methods, and personality assessment.
Identity, Narcissism and Defense Mechanisms in Late Adolescence
Journal of Research in Personality, 29, 341-361 (1995)
The relationships among Marcia's (1980) identity status, the components of
narcissism, and three ego defense mechanisms (denial, projection and
identification) were studied in a group of late adolescents as they began
college. The results indicated that experiencing an identity crisis (statuses
of Moratorium and Diffusion/Moratorium) was associated with the use of all
three defenses, but not with narcissism. Commitment to an identity without
having experienced a crisis (Achieved status) was associated with both adaptive
and defense narcissism and minimally with the defense of identification.
Self-Concept in Children's Figure Drawings
H-T-P Viewpoint, 1 (1996)
The figure drawings on sixth-grade students were evaluated for figure size and
physical distance between self and friend. Children who were independently
assessed as being high in social self-competence drew the figures of self and
friend closer together than did children low in social self-competence. Also,
children who were independently assessed as being high in global self-worth
drew themselves with more positive facial expressions than did children who
were low in self-worth.
The Effects of Suspicion on Attributional Thinking and the Correspondence
Bias
Journal of Personality and Social Psychology, 70, 1164-1185 (1996)
This research examines why suspicion of ulterior motives leads perceivers to
avoid the correspondence bias in the assigned-essay paradigm, in contrast to
information about situational constraint. Five experiments offer converging
evidence that suspicion triggers active, sophisticated attributional thinking.
In addition, these studies: (1) Examine subjects' spontaneous thoughts and
attributional analyses in the context of high-constraint or ulterior-motive
conditions, (2) Suggest that high-constraint and ulterior-motive information
have divergent effects on perceivers early in the inference process, (3)
Demonstrate the correspondence bias in studies that minimize demand
characteristics, and (4) Find that the effects of suspicion can endure across
targets and contexts. The implications of these results for current models of
the correspondence bias and the dispositional inference process, and
suggestions for a revised model, are discussed.
Prenatal Alcohol Exposure Alters The Functional Responsiveness
of The
SNS in Brown Adipose Tissue.
Alcoholism: Clinical and Experimental Research 19 (2), 18
(1995).
Prenatal alcohol exposure causes a delay in thermoregulation in rat pups that
is associated with an increased norepinephrine (NE) concentration and an
increased density of NE ß1 receptors in brown adipose tissue
(BAT) at 20 days of age. This increased NE concentration is not, however,
accompanied by an increased density of NE transporter protein sites, suggesting
that the increased NE is not due to increased SNS terminals. This experiment
further examined the effects of prenatal alcohol exposure on the developing SNS
by assessing the functional thermal responsiveness of BAT after pharmacological
challenge with amphetamine sulfate (0.5-4 mg/kg) and isoproterenol
hydrochloride (50-100 mg/kg) in 20 day old subjects (35% EDC liquid diet
paradigm). Compared to the pair-fed and standard control offspring, prenatal
alcohol exposed offspring were more sensitive to isoproterenol, a direct
agonist, as would be expected with a greater NE receptor density.
Alcohol-exposed offspring were less sensitive to low doses of amphetamine, but
more responsive to high doses, than controls. These results suggest an
alcohol-related deficit in NE release mechanisms in the SNS; this deficit may
contribute to hyper-responsiveness to stress in FAS or FAE infants.
The Effects Of Lactational Alcohol Exposure on Neuromotor Development,
Activity,
and Learning In Rats
Alcoholism: Clinical and Experimental Research 19 (2), 103
(1995)
Although the behavioral effects of prenatal alcohol exposure have been well
documented in humans and animal models, relatively less attention has been paid
to the potential adverse behavioral consequences of lactational alcohol
exposure. In this experiment, Long Evans hooded primiparous female rats were
assigned to one of five postnatal treatment groups on the day after
parturition; treatments were administered until 15 days postpartum. Group 1
were intubated with 4 g/kg ethanol daily. Group 2 were intubated with an
equivalent volume of distilled water. Group 3 were given ad lib access to an
alcohol liquid diet (35% EDC; Bioserve F1265) with group 4 receiving a yoked
pair-fed liquid diet (0% EDC; Bioserve F1264). Group 5 received standard lab
chow and water ad lib. Offspring were assessed for neuromotor development at
3-10 days, open field activity at 16 days, and Morris water maze spatial
learning at 22-25 days. Both alcohol groups (1 & 3) took longer to ascend
an inclined ramp and were hypoactive in the open field compared to the three
control groups. Various deficits in spatial learning were seen in all
experimental groups compared to Group 5. These results suggest that alcohol
exposure via breast milk may have significant adverse behavioral sequelae.
The Social Psychology of False Confessions: Compliance, Internalization,
and Confabulation
Psychological Science, 7, 125-128 (1996)
An experiment demonstrated that false incriminating evidence can lead people to
accept guilt for a crime they did not commit. Subjects in a fast- or
slow-paced reaction time task were accused of damaging a computer by pressing
the wrong key. All were truly innocent and initially denied the charge. A
confederate then said she saw the subject hit the key or did not. Compared to
subjects in the slow-no witness group, those in the fast-witness group were
more likely to sign a confession, internalize guilt for the event, and
confabulate details in memory consistent with that belief. Both legal and
conceptual implications are discussed.
Clues to a Child's Mind
Contemporary Psychology, 40, 960-961 (1995)
Delay-Discounting Probabilistic Rewards: Rates Decrease as Amounts
Increase
Psychonomic Bulletin & Review, 3(1), 100-104 (1996)
The independence of delay-discounting rate and monetary reward size was tested
by offering subjects (n = 621) a series of choices between immediate
rewards and larger, delayed rewards. In contrast to previous studies using
hypothetical rewards, subjects were entered into a lottery in which they had a
chance of actually receiving one of their choices. The delayed rewards were
grouped into small ($30-$35), medium ($55-$65), and large amounts ($70-$85).
Discounting rates were estimated for all three reward sizes for each subject on
the basis of their pattern of choices using a novel parameter estimation
procedure. The data indicate that the discounting rate is a decreasing
function of the size of the delayed reward (p < .0001), whether
hyperbolic or exponential discounting functions are assumed. In addition, a
reliable gender difference was found (p = .005), with males discounting
at higher rates than females, on average.
Modeling myopic decisions: Evidence for Hyperbolic Delay-Discounting
Within Subjects and Amounts
Organizational Behavior and Human Decision Processes, 64(1),
22-30 (1995)
Hyperbolic and exponential discounting functions were compared as models of
subjects' present valuations of delayed rewards. Previous comparisons have
been limited by relying on the assumption that discounting rate is independent
of reward size; we avoided this limitation by making all comparisons within
reward sizes. In Experiment 1, using real rewards in a simulated auction, and
in Experiment 2, using hypothetical rewards, we offered subjects 5 monetary
rewards at 6 delays each, and asked them to indicate the smallest amount they
would accept immediately in exchange for those rewards. Both discounting
functions were then fit to the 6 reported amounts for each reward using
nonlinear regressions. In both experiments, although both functions fit the
data very well, the hyperbolic function fit better for all of the delayed
rewards. Furthermore, the hyperbolic function better described the data for 20
of 21 subjects, and 14 of 18 subjects in Experiments 1 and 2, respectively.
A Computational Model of Cholinergic Disruption of Septohippocampal Activity
in Classical Eyeblink Conditioning
Neurobiology of Learning and Memory, 66 (1996)
A previous neurocomputational model of corticohippocampal interaction (Gluck
& Myers, 1993) can provide a framework for examining the behavioral effects
of septohippocampal modulation during classical conditioning. The model
assumes that the hippocampal region is necessary for forming new stimulus
representations during learning. but not for the formation of simple
associations. This paper considers how septohippocampal interaction could
affect this function. The septal nuclei provide several modulatory inputs to
the hippocampus, including a cholinergic input which Hasselmo (1995) has
suggested may function to regulate hippocampal dynamics on a continuum between
two states: a storage state in which incoming information is encoded as an
intermediate-term memory and a recall state when this information is
reactivated. In this theory, anticholinergic drugs such as scopolamine should
disrupt learning by selectively reducing the hippocampus's ability to store new
information. An approximation of Hasselmo's idea can be implemented in the
corticohippocampal model by a simple manipulation of hippocampal learning rate;
this manipulation is formally equivalent to adjusting the amount of time the
hippocampus spends in learning and recall states. With this manipulation, the
model successfully accounts for the effects of scopolamine in retarding
classical conditioning in humans (Solomon, Groccia-Ellison, et al., 1993) and
animals (Solomon, et al. 1983). The model further predicts that although
cholinergic agonists (such as Tacrine) may improve learning in subjects with
artificially depressed brain acetylcholine levels, there may be limited memory
improvement in normal subjects from such cholinergic therapy. This is
consistent with the general finding of a U-shaped dose response curve for
cholinergic drugs in normal subjects: low to moderate doses may improve
learning, but higher doses are ineffective or even degrade learning (e.g.,
Ennaceur & Meliani, 1992; Dumergy, Derer, et al, 1988).
Classic Conditioning in Aged Rabbits: Delay, Trace, and Long-Delay
Conditioning
Behavioral Neuroscience, 110, 1-9 (1996)
Young (0.5 years) and aged (2+, 3+ and 4+ years) rabbits underwent acquisition
of the classically conditioned nictitating membrane response in a delay (500-ms
conditioned stimulus (CS), 400-ms interstimulus interval (ISI), long-delay
(1000-ms CS, 900-ms ISI), or trace (500-ms CS, 400-ms stimulus-free period)
paradigm. Collapsing across age groups, there is a general tendency for
animals to acquire trace conditioning more slowly than delay conditioning.
Collapsing across conditioning paradigms, there is a general tendency for aged
animals to acquire more slowly than younger animals. Of greater significance,
however, are the age differences in the different conditioning paradigms. In
the delay and long-delay paradigms, significant conditioning deficits first
appeared in the 4+-year-old group. In the trace conditioning paradigm,
significant conditioning deficits became apparent in the 2+-year-old animals.
Science and Television Commercials:
Adding Relevance to the Research
Methodology Course
In M. E. Ware and D. E. Johnson, Handbook of Demonstrations and Activities
in Psychology, Volume I, 230-234 (1996).
The Tolerability and Safety Profile of Tacrine
Reviews in Contemporary Pharmacotherapy, 6(7), 349-358 (1995).
Diagnosis and Treatment of Alzheimer's Disease, with Special Reference to
Tacrine
Therapeutic Strategies with the Older Adult, 3, 1-20 (1995).
Alzheimer's disease is the leading cause of dementia in adults in the United
States. As stated in this lesson, approximately 4 million adults suffer from
the disease, accounting for 65% of all cases of dementia. To offer effective
services to a person suffering from Alzheimer's disease (AD) and to that
person's caregivers, health care professionals must possess a solid
understanding of both dementia and the disease itself--its symptoms, causes,
nature, and the implications they hold for delivering effective treatment and
counseling services. In this lesson, the authors review the nature of
Alzheimer's disease and discuss the use of tacrine (a cholinergic agonist that
functions as a reversible inhibitor of butylcholinesterase and
acetylcholinesterase) in its treatment.
Long-Term Treatment Effects of Tacrine in AD Patients
Annals of Neurology, 38, 291 (1995)
Tacrine (Cognexr, THA), a centrally acting acetylcholinesterase
inhibitor, is approved for the symptomatic treatment of Alzheimer's disease
(AD). One of the studies (Knapp et al. JAMA 1994) on which this approval was
based was a 30 week, double-blind, placebo-controlled, parallel design study
that demonstrated beneficial effects of tacrine as measured by an objective
neuropsychological instrument, the Alzheimer's Disease Assessment
Scale-cognitive portion (ADAS-Cog). Data regarding longer term effects of the
drug are lacking, and will likely not be forthcoming from a large, prospective
trial because of ethical and practical reasons. The purpose of the present
retrospective study was to evaluate the effects of tacrine in AD patients over
a 17-21 month period. All patients were followed by the Memory Disorders
Clinic at Southwestern Vermont Medical Center. Tacrine patients (n=12) were
initially entered in the double blind portion of the Knapp et al. study, and
assigned to either the 120 or 160 mg/day tacrine group. They subsequently
entered the open label extension portion of the study and were maintained on
either 120 or 160 mg/day. Untreated controls (age, gender, general health and
education matched, n=12) visited the clinic with equal frequency during the
same time interval. Patients were administered the ADAS-Cog at regular
intervals. The results showed that tacrine patients performed significantly
better than untreated controls on the ADAS-Cog (p's <.05) at 5-9 months (7.2
point difference), 11-15 months (8.6 point difference), and 17-21 months (8.3
point difference). These data provide preliminary evidence that tacrine can
benefit AD patients compared to untreated controls for periods of up to 17-21
months.
Nimodipine Facilitates Retention of the Classically Conditioned Nictitating
Membrane Response in Aged Rabbits Over Long Retention Intervals
Neurobiology of Aging, 791-796 (1995)
Aged rabbits initially underwent 18 days of acquisition of the classically
conditioned nictitating membrane response (NMR) using a tone conditioned
stimulus (CS) and an air puff unconditioned stimulus (UCS). They were then
treated with a low or high dose of nimodipine or a vehicle for 90 days. During
this time no further CS-UCS pairings were presented. They underwent testing
for retention of the conditioned response (CR) at 30 and 90 days. Retention
testing consisted of 20 presentations of the CS alone. Rabbits in the control
condition retained 46.4% of their predrug levels of conditioned responding and
rabbits receiving the low dose of nimodipine retained 37.3% of their predrug
levels after 30 days. After 90 days, retention in these animals declined to
8.1% and 14.1% respectively. In contrast, rabbits receiving the high dose of
nimodipine retained 85% of their predrug learning at 30 days with little
decline at 90 days (77.1%). Nonassociative factors such as sensitivity to the
CS or UCS could not explain these effects.
The Reverse-Inference Effect in Free Recall
Journal of Experimental Psychology: Learning, Memory, and Cognition
22(2), 430-437 (1996).
D.J. Burns (1989) demonstrated that free recall of second-list response terms
was better in an interference (A-B, A-C) condition than in the control (D-B,
A-C) condition. This reversal of the traditional interference effect is
referred to as the reverse-interference effect. Results from Experiments 2-4
in this article discounted several possible explanations of the
reverse-interference effect, and the results from Experiment 5-7 supported a
stimulus-accessibility account of the reverse-interference effect. That is,
when asked for free recall of the response terms, subjects covertly retrieve
stimulus terms to serve as cues for the responses. The reverse-interference
effect reflects the greater accessibility of stimulus terms in the interference
condition than in the control condition.
Seeing the Forest for the Trees: Addressing the Plight of the Novice
Student
Contemporary Psychology, 41(5), 442, (1996)
A Strategic Account of the Cue-Depreciation Effect
Canadian Journal of Experimental Psychology, 49(4), 513-519
(1995).
A word fragment is less likely to be completed if it is presented incrementally
(R _ _ _ _ _ _ P, R _ _ _ _ R _ P, R _ I _ _ R _ P, R _ I _ _ R O P) than if it
presented all at once (e.g., R _ I _ _ R O P). This phenomenon is known as the
cue-depreciation effect. The present study examined the role of strategies in
this phenomenon. The magnitude of the cue-depreciation effect was increased
when subjects were asked to adopt a passive generation approach to word
fragment completion. The current study investigated an extension of Bruner and
Potters (1964) early hypothesis-generation account of the cue-depreciation
effect. Findings demonstrate the importance of completion strategies for a
general theory of fragment completion.