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ABSTRACTS OF FACULTY PUBLICATIONS


ASTRONOMY

The Earliest Comet Photographs: Usherwood, Bond, and Donati 1858

Jay M. Pasachoff, Roberta J.M. Olson, and Martha L. Hazen

Journal for the History of Astronomy, 27, 129-145, 1996.

Comets and Meteors in the 18th and 19th Century British Art and Science

Jay M. Pasachoff and Roberta J.M. Olson

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

R.B.C. Henry, K.B. Kwitter and J.W. Howard

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

M.S. Raljevic, F. Zaratti, and J.M. Pasachoff

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

Jay M. Pasachoff, B. Babcock, and K. Reardon 1995

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

Jay M. Pasachoff, B. Babcock, J.S. Diaz 98, K. Reardon 92, and R. Nichols-Kiley 98

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.

CHEMISTRY

Determination of Polychlorinated Biphenyls (PCBs) in River and Bay Sediments

Susan E. Kegley, Assistant Professor of Chemistry, Kristen J. Hansen 91,
and Kevin L. Cunningham

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

J. Hodge Markgraf, Professor of Chemistry, Manuel Finkelstein, Part-Time Lecturer in Chemistry, and John R. Cort 91

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

J. Hodge Markgraf, Professor of Chemistry, and Daniel E. Patterson 95

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

Anne F. Skinner and Mark N. Rudolph96

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

June E. Mirecki (University of Delaware), John F. Wehmiller (University of Delaware), Anne F. Skinner

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.

COMPUTER SCIENCE

PolyTOIL: A Type-Safe Polymorphic Object-Oriented Language

Kim B. Bruce, Professor of Computer Science, Angela Schuett 94, and Robert van Gent 93

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

Kim B. Bruce, Professor of Computer Science

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

Christopher J. Merz and Michael J. Pazzani, University of California, Irvine
Andrea Danyluk, Assistant Professor of Computer Science

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

William Lenhart, Professor of Computer Science, Giuseppe Liotta, Brown University

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.

GEOLOGY

Orthacean and Strophomenid Brachiopods From the Lower Silurian
of the Central Oslo Region

B. Gudveig Baarli, Research Associate

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

Mary Ann Hirshfeld 96, David P. Dethier, Professor of Geology

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

Willard S. Morgan 96, David P. Dethier, Professor of Geology

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

David P. Dethier, Professor of Geology, Steven L. Reneau, Los Alamos National Laboratory

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

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

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

Rebecca L. Beavers, Duke Univ. Marine Lab, H. Allen Curran, Smith College; William T. Fox, Professor of Geology, Williams College

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

Markes E. Johnson, Professor of Geology; W. S. McKerrow, Bernhard Visiting Professor of Geology, 1991

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

Markes E. Johnson, Professor of Geology, B. Gudveig Baarli, Research Associate; James H. Scott, Jr. 92

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

Markes E. Johnson, Professor of Geology
Jorge Ledesma-Vazquez, Universidad Autonoma de Baja California
Hovey C. Clark 94, Jennifer A. Zwiebel 94

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)

Rong Jia-yu, Nanjing Inst. of Geology and Palaeontology; Markes E. Johnson, Professor of Geology

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

Paul Karabinos, Professor of Geology, et al.

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

Paul Karabinos, Professor of Geology

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

Paul Karabinos, Professor of Geology, Demian M. Saffer 95

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

Demian M. Saffer, University of California Santa Cruz, P Karabinos, Professor of Geology

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

S. J. Seaman, University of Massachusetts, R. A. Wobus, Professor of Geology

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.

MATHEMATICS

Unknotting Tunnels in Hyperbolic 3-Manifolds

Colin C. Adams, Professor of Mathematics

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

Colin Adams, Professor of Mathematics

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

Frank Morgan, Professor of Mathematics, Herman Gluck, Dana Mackenzie

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

Frank Morgan, Professor of Mathematics

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

Frank Morgan, Professor of Mathematics

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

Frank Morgan, Professor of Mathematics

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

Frank Morgan, Professor of Mathematics

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?

Frank Morgan, Professor of Mathematics

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

Cesar E. Silva, Associate Professor of Mathematics, Philippe Thieullen

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.

PHYSICS

Period Doubling and Quasi-periodicity in Additive-pulse Mode Locked Lasers

G. Sucha, S.R. Bolton, Assistant Professor of Physics, S. Weiss and D.S. Chemla

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

Ephraim Fischbach, Dennis E. Krause, Assistant Professor of Physics, Carrick Talmade and Dubravko Tadic

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

Dubravko Tadic, Dennis E. Krause, Assistant Professor of Physics, Ephraim Fischbach and Daniel Sudarsky

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

Protik K. Majumder, Assistant Professor of Physics, D.M. Meekhof, P.A.Vetter, S.K. Lamoreaux, and E.N. Fortson (University of Washington).

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

Protik K. Majumder, Assistant Prof. of Physics

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

William K. Wootters, Professor Physics, et al.

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

William K. Wootters, Professor of Physics, et al.

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.

PSYCHOLOGY

Story-Telling, Narrative and the Thematic Apperception Test

Phebe Cramer, Professor of Psychology

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

Phebe Cramer, Professor of Psychology

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

Amy Baughcum, 97 and Phebe Cramer, Professor of Psychology

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

Steven Fein, Assistant Professor of Psychology

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.

Betty Zimmerberg, Associate Professor of Psychology, and Grace J. Wang 96

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

Betty Zimmerberg, Associate Professor of Psychology, and Kristin Edwards 96.

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

Saul M. Kassin, Professor of Psychology, and K. L. Kiechel 94

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

Review by Robert D. Kavanaugh, Hales Professor of Psychology

Contemporary Psychology, 40, 960-961 (1995)

Delay-Discounting Probabilistic Rewards: Rates Decrease as Amounts Increase

Kris N. Kirby, Assistant Professor of Psychology; Nino N. Marakovi '94

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

Kris N. Kirby, Assistant Professor of Psychology; Nino N. Marakovic 94

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

Paul R. Solomon, Professor of Psychology, et al.

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

Paul R. Solomon, Professor of Psychology and MaryEllen Groccia

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

Paul R. Solomon, Professor of Psychology

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

Paul R. Solomon, Professor of Psychology and W. W. Pendlebury

Reviews in Contemporary Pharmacotherapy, 6(7), 349-358 (1995).

Diagnosis and Treatment of Alzheimer's Disease, with Special Reference to Tacrine

Paul R. Solomon, Professor of Psychology and William W. Pendlebury, MD

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

Paul R. Solomon, Professor of Psychology, Mahri Relin 95, Bridget Kelly 95, MaryEllen Groccia and W. W. Pendlebury

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

Paul R. Solomon, Professor of Psychology, Mika Wood 93, MaryEllen Groccia, Bo-Yi Yang, Richard Fanelli and Ronald Mervis

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

Anjali Thapar, Assistant Professor of Psychology

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

Review by Anjali Thapar, Assistant Professor of Psychology

Contemporary Psychology, 41(5), 442, (1996)

A Strategic Account of the Cue-Depreciation Effect

Anjali Thapar, Assistant Professor of Psychology, andR. L. Greene

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.


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