The Ionization Structure of Old Planetary Nebulae Which Interact with the Interstellar Medium

Richard W. Tweedy and Karen B. Kwitter

The Astronomical Journal, 108, 188-194, 1994. Four old planetary nebulae have been observed, and are found to be interacting with the interstellar medium (ISM). They appear to have commenced fairly recently in A34 and A61, since the tell-tale asymmetric brightness enhancements are present in images taken in both [N II] and [O III]. However, the [N II]/[O II] ratio is much higher in the interaction region than elsewhere, probably due to the increased densities and complicated motions expected there. By contrast, the regions of A31 and A62 which are bright in [O III] are considerably smaller than the size of the nebula visible in [N II]. We interpret this as being due to a more advanced interaction than with A34 and A62. This ionization stratification may provide a simpler approach for probing the surrounding ISM than using hydrodynamic models.

Two Planetary Nebula Candidates Around Hot DA White Dwarfs

Richard W. Tweedy and Karen B. Kwitter

The Astrophysical Journal, Letters, 433, L93-L96, 1994. Two possible planetary nebulae have been found during a search around hot H-rich white dwarfs. These are located close to Ton 320 and RE 1738 +665. Both are extremely faint, but are rather brighter in [N II] than H[[alpha]]. This would bring the total number of nebulae found around independently identified hot DA white dwarfs to four, with one other around a PG 1159 star. In addition, we failed to detect any around six PG 1159 stars. We suggest that this lack is very difficult to explain if all white dwarfs undergo essentially the same evolution, each passing through a PG 1159 stage. Furthermore, the most widely quoted alternative, in which ~25% undergo a late He-shell flash causing a brief return to the AGB, can successfully explain this only if it produces a substantially greater delay than is currently assumed.

Two Planetary Nebula Candidates Around Hot DA White Dwarfs

Richard W. Tweedy and Karen B. Kwitter

The Astrophysical Journal, Letters, 433, L93-L96, 1994. Two possible planetary nebulae have been found during a search around hot H-rich white dwarfs. These are located close to Ton 320 and RE 1738 +665. Both are extremely faint, but are rather brighter in [N II] than H[[alpha]]. This would bring the total number of nebulae found around independently identified hot DA white dwarfs to four, with one other around a PG 1159 star. In addition, we failed to detect any around six PG 1159 stars. We suggest that this lack is very difficult to explain if all white dwarfs undergo essentially the same evolution, each passing through a PG 1159 stage. Furthermore, the most widely quoted alternative, in which ~25% undergo a late He-shell flash causing a brief return to the AGB, can successfully explain this only if it produces a substantially greater delay than is currently assumed.

Comets and Meteors in 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 Comparing paintings, drawings and prints of comets and meteors in British works of art and scientific records of the 18th and 19th centuries brings us to a study of the relationship between science and art. Representations were sometimes naturalistic, sometimes symbolic and sometimes satirical. The British interest in images of comets and meteors, which were not clearly distinguished from each other during much of the period, coincided with the era that celebrated the progress in science exemplified by the discoveries of Newton (1687 for his Principia) and Halley (1705 for his comet calculations). At the end of the period in question, the invention of photography, and its subsequent improvement to the point where faint objects like comets could be recorded, altered the dynamics. The changes in both intellectual climate and technology resulted in an increasing separation between the arts and the sciences.


Spinal Cord Regeneration in Adult Goldfish:
Implications for Functional Recovery in Vertebrates

Steven J. Zottoli, Professor of Biology, Adrienne P. Bentley, Deborah G. Feiner, John R. Hering, Brian J. Prendergast and Heather I. Reiff

Progress in Brain Research, 103, Chap. 18, 219-228 (1994) The spinal cord of adult teleost fish has a high degree of regenerative capacity after injury (see reviews by Windle, 1955, 1956 and Bernstein, 1988). After spinal cord transections at the high thoracic to cervical levels, fish (Carassius vulgaris; Carassius auratus; Cyprinus carpio; Oryzias latipes) first lay on their sides and then gradually recovered some motor behaviors from about 15 days to 2 months postoperatively (Koppányi and Weiss, 1922; Tuge and Hanzawa, 1935-1937; Pearcy and Koppányi, 1941; reviewed by Koppányi, 1955). Although many animals appeared `normal,' some adult fish had partial or no behavioral regeneration 2-3 months postoperatively (Tuge and Hanzawa, 1937; Pearcy and Koppányi, 1941). Cases of incomplete behavioral regeneration were most apparent when fish were lesioned at the cervical spinal cord level. Specifically, none of the fish with cervical spinal wounds recovered equilibrium during postoperative intervals of 40-64 days, although swimming became ore coordinated (Tuge and Hanzawa, 1935, 1937). Such results indicate that the success of behavioral regeneration in adult teleost fish may be determined, in part, by the level of spinal cord damage. To determine what factors may limit behavioral regeneration at more rostral lesion sites, we have studied the response of central nervous system (CNS) neurons to spinal cord crush at the spino-medullary level (SML, the junction between the spinal cord and medulla oblongata; this level is the equivalent of the cervical spinal cord level of Tuge and Hanzawa [1935] and is just rostral to the first ventral root). Many injured CNS cells, including vestibulospinal and reticulospinal neurons, do not make the same pathway choice as they made during development. Instead they extend axons into the first ventral root, away from their normal target areas in the spinal cord. This shift in direction may limit behavioral recovery.


Analysis of the SOS Inducing Signal in Bacillus subtilis using Escherichia coli LexA as a Probe

Charles M. Lovett, Jr., Thomas M. O'Gara, and James N. Woodruff '88

Journal of Bacteriology, 176, 4914-4923 (1994). We analyzed the Bacillus subtilis SOS response using Escherichia coli LexA protein as a probe to measure the kinetics of SOS activation and DNA repair in wild-type and DNA repair-deficient strains. By examining the effects of DNA damaging agents that produce the SOS inducing signal in E. coli by three distinct pathways, we present evidence that the nature of the SOS inducing signal has been conserved in B. subtilis. In particular, we used the B. subtilis DNA polymerase III inhibitor, 6-(p-hydroxyphenylazo)-uracil, to show that DNA replication is required to generate the SOS inducing signal following UV irradiation. We also present evidence that single-stranded gaps, generated by excision repair, serve as part of the UV inducing signal. By assaying the SOS response in B. subtilis dinA, dinB, and dinC mutants we identified distinct deficiencies in SOS activation and DNA repair that suggest roles for the corresponding gene products in the SOS response.

Infrared Optical Constants of H2O Ice, Amorphous Nitric Acid Solutions,
And Nitric Acid Hydrates

Birgit G. Koehler, Assistant Professor of Chemistry, Owen B. Toon, Margaret A. Tolbert,
Ann M. Middlebrook, and Joseph Jordan

Journal of Geophysical Research, 99, 25631-25654 (1994) We determined the infrared optical constants of nitric acid trihydrate, nitric acid dihydrate, nitric acid monohydrate, and solid amorphous nitric acid solutions that crystallize to form these hydrates. We have also found the infrared optical constants of H2O ice. We measured the transmission of infrared light through thin films of varying thickness over the frequency range from about 7000 to 500 cm-1 at temperatures below 200 K. We developed a theory for the transmission of light through a substrate that has thin films on both sides. We used an iterative Kramers-Kronig technique to determine the optical constants that gave the best match between measured transmission spectra and those calculated for a variety of films of different thickness. These optical constants should be useful for calculations of the infrared spectrum of polar stratospheric clouds.

Preparation of (S)-(+)-5,8a-Dimethyl-3,4,8,8a-tetrahydro-1,6-(2H,7H)-naphthalenedone

J. Hodge Markgraf, Professor of Chemistry, John F. Fei `93,
and Robert E. Ruckman `95

Journal of Chemical Education, 72, 270-271 (1995) The title compound was prepared from ethyl vinyl ketone and 2-methyl-1,3-cyclohexanedione. The annulation step, catalyzed by (S)-phenylalanine, afforded the chiral product in good yield with high enantiomeric excess. The two-step sequence was developed as an advanced undergraduate experiment in asymmetric synthesis.

A 15N NMR Study of N-Phenylazoles

J. Hodge Markgraf, Professor of Chemistry, and Joseph P. Sadighi `94

Heterocycles, 40, 583-595 (1995) The 15N chemical shifts for a series of eleven N-phenylazoles were determined. A triazole and four tetrazoles were prepared with 15N enrichment at specific sites. A new synthesis of 1-phenyl-1,2,3-triazole was developed. Assignments of 15N peaks for all possible compounds from 1-phenylpyrrole to the diphenyltetrazoles were made.

ESR Dating Of Terrestrial Quaternary Shells

Anne R. Skinner, Part-time Lecturer, and Catherine E. Shawl `95

Quaternary Geochronology (Quaternary Science Reviews) 13, 679-684 (1994) Multiple geological processes over the last 100ka have resulted in a complex stratigraphy for San Salvador Island, The Bahamas. A study of amino acid racemization in the land snail sp. Cerion was inconclusive in resolving this, and therefore an investigation of the same species using ESR was undertaken. Sample ages range from 4 to 150 ka. The newer shells represent one of the youngest ESR sample sets known, and the first attempt to use terrestrial species. The ages obtained correlate generally with stratigraphic expectations, but until further work is done on the environmental history, the numerical values should be considered relative rather than absolute.

Collisional Quenching Corrections for Laser-Induced Fluorescence
Measurements of NO A2[[Sigma]]+

P.H. Paul, J.A. Gray, J.L. Durant, Jr., and J.W. Thoman, Jr.,
Associate Professor of Chemistry

AIAA Journal, 32, 1670 (1994). Quantitative combustion diagnostics using laser-induced fluorescence require a knowledge of energy transfer and quenching rates at elevated temperatures. Such information is critical both for experimental design and for subsequent reduction of measured signals to measurements of temperature and species concentrations. We present the results of a study of electronic energy transfer in NO A2[[Sigma]]+. These results are cast in the form of empirical correlations which have been developed to facilitate the practical applications of quenching corrections. The choice of particular functional forms for these correlations is based on a classical collisional model of the process. This model has been calibrated against an extensive set of measured cross-sections. Results are presented for a number of species of interest in combustion and aerothermodynamic applications.

Correlations for the NO A2[[Sigma]]+ (v'=0) Electronic Quenching Cross-section

P.H. Paul, C.D. Carter, J.A. Gray, J.L. Durant, Jr.,
J.W. Thoman, Jr., Associate Professor of Chemistry, and M.R. Furlanetto '91

Sandia Report , SAND94-8237, Sandia National Laboratories, Albuquerque, NM (1994). This report summarizes recent progress in the development of a model for collisional electronic quenching of NO A2[[Sigma]]+ by a number of molecules commonly found in combustion and aerodynamic systems. The model provides a means to reliably extend the measurement data base as well as suggesting simple analytic forms that can be used to provide physically plausible fits to the measurements. This report also contains a compilation of the available experimental data for collisional electronic quenching of NO A2[[Sigma]]+.

Near-resonant Electronic Energy Transfer in the Electronic Quenching
of NO A2[[Sigma]]+ by Hydrocarbons and Ammonia

M.R. Furlanetto '91, J.W. Thoman, Jr., Associate Professor of Chemistry, J.A. Gray,
J.L. Durant, Jr., and P.H. Paul

J. Chem. Physics., 101, 10452 (1994). We report rate coefficients for the electronic quenching of NO A2[[Sigma]]+ v=0 by several fuel gases, methane, ethane, propane, ethene, and ethyne, and by ammonia over a wide temperature range (300 - 2300 K). High temperature data is obtained behind reproducible shock waves. High-temperature quenching of NO by many species has previously been explained by a charge-transfer (harpoon) model. However, we find such a model unable to explain a portion of the quenching behavior reported here. Instead, we propose a near-resonant electronic energy transfer mechanism is active.


A Paradigmatic Object-Oriented Programming Language: Design, Static Typing and Semantics

Kim B. Bruce, Professor of Computer Science

Journal of Functional Programming 4, (1994), 127-206. In order to illuminate the fundamental concepts involved in object-oriented programming languages, we describe the design of TOOPL, a paradigmatic statically-typed functional object-oriented programming language which supports classes, objects, methods, hidden instance variables, subtypes, and inheritance.

It has proven to be quite difficult to design such a language that does not contain holes in the type system. A particular problem with statically type checking object-oriented languages is designing type-checking rules that ensure that methods provided in a superclass will continue to be type correct when inherited in a subclass. The type-checking rules for TOOPL have this feature, enabling library suppliers to provide only the interfaces of classes with actual executable code, while still allowing users to safely create subclasses.

The design of TOOPL has been guided by an analysis of the semantics of the language, which is given in terms of a model of the F-bounded second-order lambda calculus with fixed points at both the element and type level. This semantics supported the language design by providing a means to prove that the type-checking rules are sound, providing a guarantee that the language is type-safe.

While the semantics of our language is rather complex, involving fixed points at both the element and type level, we believe that this reflects the inherent complexity of the basic features of object-oriented programming languages. Particularly complex features include the implicit recursion inherent in the use of the keyword, self, to refer to the current object, and its corresponding type, MyType. The notions of subclass and inheritance introduce the greatest semantic complexities, whereas the notion of subtype is relatively straightforward.

Proximity Drawability: A Survey

Giuseppe Di Battista, University of Rome, La Sapienza
William Lenhart, Associate Professor of Computer Science
Giuseppe Liotta, University of Rome, La Sapienza

Proceedings of the DIMACS International Workshop, Graph Drawing '94
Lecture Notes in Computer Science, 894, Springer-Verlag, 328-339 (1994)
Proc. of Am. Math. Soc., 106, 269-271 (1989) A proximity graph is a graph obtained by taking a set P of points in the plane, and connecting with straight line segments pairs of points of P considered to be close together according to some definition of "proximity." Recently, increasing attention has been given to the proximity drawing problem: Given a graph G and a definition of proximity, determine whether a set P of points exists such that the proximity graph of P is the given graph, and if so, compute such a set.

Proximity drawings have several interesting features. They are usually unaffected by changes in scale, since the measures of proximity used are based on relative distances between points. Also, adjacent vertices are drawn (relatively) more closely together than non-adjacent vertices, and vertices not incident to a particular edge are not drawn too close to the edge. Furthermore, neighbors of a given vertex tend to cluster together. This paper aims to give a survey of the central problems and results in this area. Our presentation is organized hierarchically around some common features of most proximity drawings, in particular the unifying concept of what we call a (k, n)-proximity drawing.

Proximity Constraints and Representable Trees

Prosenjit Bose, McGill University
Giuseppe Di Battista, University of Rome, La Sapienza
William Lenhart, Associate Professor of Computer Science
Giuseppe Liotta, University of Rome, La Sapienza, Laurie Heatherington, Assistant

Proceedings of the DIMACS International Workshop, Graph Drawing '94
Lecture Notes in Computer Science, 894, Springer-Verlag, 340-351 (1994) A proximity drawing of a graph is one in which vertices that are adjacent are drawn relatively closer together than those which are not. In this paper we study the proximity-drawability testing problem, i.e., the problem of deciding whether a graph has a proximity drawing with a given type of proximity region.

In particular, we study the proximity-drawability of trees. We consider an infinite family of parameterized proximity regions, that include the most well-known proximity regions presented in the literature.


Thick Glacial Drift and Divergent Striae: Clues to Changes in Ice Flow During Retreat of Continental Ice Through the San Juan Is., Washington

Daniel P. White `94
Christopher M. Brookfield `94
David P. Dethier, Professor of Geology

GSA Abstracts with Programs, 26 (7), 307 (1994) Sedimentologic evidence and striae from the San Juan Islands, WA, suggest that Cordilleran ice eroded large volumes of sediment as flow reoriented during ice retreat. We analyzed the thickness of glacial drift in some 1400 well logs, measured striae on a reconnaissance basin in eight 7.5' quadrangles, and collected extensive striae measurements at the best-preserved sites. The detailed measurements show the full range of preserved striae and allowed us to test a statistical method for determining the relative chronology of divergent striae.

Analysis of striae and drumlins suggests that retreating Cordilleran ice initially flowed toward 230o, then 220o, and finally parallel to local trough directions (270o to 160o) as the ice margin became lobate before about 13.2 ka. As much as 100 m of late Pleistocene glacial deposits was removed during ice retreat, leaving average sediment thickness <10 m. Extensive areas of advance outwash >80 m thick, however, are preserved on Lopez and Orcas Is., and two marine moraines >90 m thick were constructed on San Juan Island. SW flow indicators suggest that ice and subglacial meltwater streams stripped sediment from most of the San Juan Islands and from adjacent troughs such as San Juan Channel, depositing it at the grounded ice margin tens of km south of the islands at about 13.5 ka. As ice calved back to the NE, by about 13.2 ka flow was toward 200o (trough parallel) when moraines were constructed on bedrock benches at Cattle Point and Pear Point, San Juan Island. These data suggest that during retreat, the ice margin responded first to regional flow, then to drawdown induced by a western calving margin in the Strait of Juan de Fuca, and finally to local topographic control as the glacier broke into sinuous tongues.

Chronology of Latest Pleistocene Ice Retreat and Isostatic Rebound,
Northern Puget Lowland, Washington

David P. Dethier, Professor of Geology

GSA Abstracts with Programs, 26 (7), 512 (1994) The SW margin of Cordilleran (Fraser) ice retreated from latitude 48o to 49o N (the International Boundary) between 14,000 and 13,200 14C yr B.P. (13.2 ka), allowing marine waters to flood the northern Puget Lowland to elevations as high as 150 m. Published 14C ages from shell and peat and new shell ages suggest most of the retreat took <500 yr at rates >0.2 km yr--1. Retreat occurred during warming climate, but rising sea-level in a fjord-like landscape may have controlled calving rates. Narrow zones of ice-contact sediment, mainly glaciomarine fans, mark grounding points of the retreating tidewater margin as far north as about 48o40'. North of the San Juan Is., deeper water may have produced rapid calving until the ice margin retreated into the Lower Fraser Valley, British Columbia. Dropstones are common in marine sediment between about 13.8 and 13.2 ka, but not after 13.0 ka, except near the International Boundary, where episodes of glaciomarine deposition persisted until about 12.0 ka. Late Fraser readvances, including that of Sumas ice to the Boundary area, probably reflect climatic fluctuations and the balance between sea-level rise and glacial rebound. Cordilleran ice disappeared by about 11.5 ka.

Isostatic rebound lifted glaciomarine and marine deposits through sea level at initial rates >100 m ka-1 Most areas south of 48o30' emerged between 13.2 and 12.5 ka and show no evidence of resubmergence. Stratigraphic relations at Deming Cascade foothills, however, demonstrate resubmergence and renewed glaciomarine deposition at about 12.4 ka, perhaps in response to the Sumas advance or local tectonic activity. Deepening of water at some sites in the San Juan Is. at about 12.6 ka could reflect a rapid rise in eustatic sea level. Rebound rates slowed in most areas by 11.0 ka and coastal areas began to resubmerge by 7.0 ka.

Deglaciation Chronology and Late Quaternary Pollen Record from Woodford Bog,
Bennington County, Vermont

Thompson P. Davis, Bentley College
David P. Dethier, Professor of Geology
Rudy Nickmann, Landing, NJ

GSA Abstracts with Programs, 27 (1), 38 (1995) A 7.7-m-long sediment core was obtained with a modified Livingstone sampler from Woodford bog, which is located at an elevation of 703m (2305 ft) on the Woodford 7.5' quadrangle in southern Vermont (42o53'50"N, 73o2'27"W). The top 2.9m consists of peat, with about 70% recovery. The peat is underlain by 3.6m of gyttja and 1.2m of low organic lake mud, each with about 90% recovery, and sand at refusal. Bulk detrital organics provided conventional radiocarbon ages of 20,575 + 1250 yrs B.P. (GX-16951) for the 7.54-7.73-m depth and 12,420 + 420 yrs B..P. (GX-16950) for the 6.72-6.82-m depth.

The chronology of retreat of the Hudson-Champlain ice lobe from SW Vermont is not well known. Regional glacial geomorphologic and stratigraphic relationships imply that upland areas probably were covered with thick ice until sometime after 18,000 yrs B.P. and that local valleys (below 300m) were ice-free by about 13,500 yrs B.P. Thus, the older radiocarbon age from Woodford bog is suspect, whereas the younger age is consistent with regional relationships and with pollen data from the bog. "Too old" conventional radiocarbon ages on basal sediments in ponds and bogs are not uncommon in New England.

The basal 0.3m of the sediment core is dominated by spruce, but grass, sedge, willow, sagebrush, and saltbush reach their percentage maxima, suggestive of a limited period of tundra vegetation. A spruce zone (35-82%) occurs between 7.3 and 5.5m, with a peak at 6.9m. An early birch zone (20-40%) occurs between 5.5 and 4.7m, concomitant with a rise in fir and pine, which peak between 5.2 and 4.8m (7-11%) and 4.6 and 4.0m (40-62%), respectively. Oak begins to increase at 4.7m with peak values (15-25%) between 3.9 and 2.7m. Hemlock begins to increase at 4.0m, with peak values (25%) at 3.1 and 1.0m. A later birch rise begins at 2.8m, followed by a rise in beech at 2.4m. The top 2.9m of the core is also marked by peak values in pollen indicative of bog vegetation, with a rise in spruce (up to 16%) between 0.4 and 0.1m. Samples are being processed for radiocarbon dating some of these pollen zones.

Penouille Spit, Evolution of a Complex Spit, Gaspé, Quebec, Canada

William T. Fox, Professor of Geology
Rebecca L. Haney, Smith College
H. Allen Curran, Smith College

Journal of Coastal Research, 11, 478-493 (1995) Penouille Spit is a complex spit located on the north shore of Gaspé Bay in Quebec, Canada. Rates of deposition and erosion were derived from old maps and serial photographs of beach ridges and shorelines on Penouille dating from 1765 to 1981. In July 1989, 41 beach ridges were mapped along 7 traverses and sediment samples were collected along 15 beach profiles. A 6-stage model of spit evolution was derived from the beach ridge and shoreline data. At Stage 1, an arcuate spit formed on a submerged deltaic platform near the mouth of the l'Eau River. During Stages 2 and 3, the Spit expanded westward about 2.1 km and rotated 20o in a counterclockwise direction. At Stage 4, erosion started at the west end of the Spit while deposition continued midway along the south shore. During Stage 5, a pair of recurved spits formed at the southeast corner of Penouille while erosion continued along West Beach. Finally by Stage 6, the south shore had rotated 40o and the corner spits converged enclosing a salt marsh at the southwest tip of the Spit. Rates of erosion along West Beach (0.50 + 0.08 m/yr) and beach ridge accretion (45.5 + 7.3 yrs/ridge) were used to estimate the net sediment flux (1,000 + 160 m3/yr) and age of the Spit (2,110 + 340 yBP). Wave refraction analysis provided evidence that Sandy Beach Spit on the south shore of Gaspé Bay blocked incoming storm waves and longshore currents, resulting in erosion along West Beach at 500 + 80 yBP.

Late Pliocene Abrasion Platform from the Cantil Costero Formation of Baja California

Jorge Ledesma-Vazquez
Markes E. Johnson, Professor of Geology

Ciencias Marinas, 20, 139-157 (1994) An unusually extensive and well-preserved marine abrasion platform of Late Pliocene age is present 84 m above sea level north of El Rosario, in Baja California. The surface extends for 6 km along the coast and is up to 3 km wide. The abrasion platform is a major disconformity that separates siltstones of the Upper Cretaceous Rosario Formation from the basal conglomerates of the Upper Pliocene Cantil Costero Formation. During its creation under transgressive conditions, the platform was kept clear of nearshore sediments and colonies of the pholadid bivalve Penitella penita (Conrad, 1837) with densities of up to 200/m2, bored into the underlying platform rocks. Tectonic uplift of the peninsula and the Sierra San Pedro Martir, starting about 2 m.y. ago, stimulated a massive progradation of land-derived clastics, which inundated the platform and locally exterminated the pholadid bivalves. This example clearly illustrates a model of transition from subtidal to intertidal conditions, in contrast to unconformities of strictly submarine origin.

Coastal Geomorphology of Andesite from the Cretaceous Alisitos Formation in Baja California

Hovey C. Clark `94
Markes E. Johnson, Professor of Geology

Journal of Coastal Research, 11, 401-414 (1995) Exposed along the Pacific shores of northern Baja California, Mexico, the Alisitos Formation includes a significant amount of andesite that formed during Middle Cretaceous time. In Late Cretaceous time, again in Late Pleistocene time, and now at present, these exhumed igneous rocks were and continue to be the resistant guardians of a rugged shore. The longevity of this rough coastline is at odds with traditional models of shoreline evolution. Features named herein "keyhole inlets" are joint-controlled openings in andesite headlands, eroded by intense wave shock on an open coast. They are narrow with a length to width ratio commonly between 3:1 and 7:1. Type 1 keyholes occur in rocks that are structurally consistent with very few joints or a multitude of chaotically oriented joints with no dominant plane of instability. Maturity of these steep-walled features is associated with the enlargement blowholes. Type II keyholes typically express much lower wall relief, forming in rocks having vertical joint planes with variable frequencies ranging between 4 and 45 joints per meter. Secondary or even tertiary joint sets may be observed at an angle subperpendicular to the first, with the result that two keyholes intersect to form an isolated sea stack. This process of coastal erosion operated on a grand scale during late Cretaceous times, when small andesite islands were separated from the mainland.

Late Pleistocene Mytilid and Petricolid Bivalves from the Open Rocky shores of Pacific Baja California (Mexico): Unusual Preservation of Macrofossils

Jennifer A. Zwiebel `94
Markes E. Johnson, Professor of Geology

Journal of Coastal Research, 11, (1995) Fossils representing species living on wave-swept, open rocky shores are seldom found preserved in the stratigraphic record. This report documents the separate occurrences of the bivalves Mytilus californianus and Petricola carditoides found associated with the Pleistocene-Cretaceous nonconformity at Punta Cabras on the Pacific coast of northern Baja California, Mexico. A pocket beach deeply incised in the steep andesite coast at Punta Cabras is the repository of both a modern beach coquina and a 3.36-meter thick, fossil shell bank consisting predominantly of transported M. californianus. Analysis of the modern beach across an onshore-offshore transect helps explain distinct stratigraphic cycles in the homologous fossil deposit. These cycles may be related to modest changes in sea level during the last interglacial period (oxygen isotope stage 5a), to extraordinary storm events, or to local uplift. At another nearby locality, fossils of P. carditoides are preserved in borings directly penetrating a gentle andesite ramp. The ramp is also partially encrusted with fossilized red coralline algae. The Mytilus deposit, with its associated gastropod and barnacle species, signifies a transported death assemblage but the Petricola population represents part of an in situ community.

Volcanic Expression of Bimodal Magmatism: The Cranberry Island-Cadillac Complex,
Coastal Maine

Sheila Seaman, Univ. of Massachusetts
R. A. Wobus, Professor of Geology, and others

Journal of Geology, 103, 301-311 (1995) The Cranberry Island series is a thick succession of Silurian volcanic breccias, ash flow tuffs, lava flows, and hypabyssal intrusions comprising the southern margin of Mount Desert Island and the Cranberry Islands of southeastern Maine. The rocks of the series preserve remarkable textures indicative of the simultaneous eruption of mafic and felsic magmas, during both explosive and effusive events. The Cadillac Mountain intrusive complex is an approximately 20-km-wide composite layered mafic to felsic plutonic body that dominates Mount Desert Island immediately north of the outcrop of the Cranberry Island series. The rocks of the Cranberry Island series and those of the Cadillac Mountain intrusive complex are correlative in age and similar in composition. The age of the Cranberry Island series, based on new U-Pb geochronology of zircon, is 424 Ma + 1 Ma. The Cadillac Mountain granite, the Somesville granite, and the Southwest Harbor granite, all parts of the Cadillac Mountain intrusive complex, are similar in composition to parts of the Cranberry Island series. The Somesville granite has been dated at 424 Ma + 2 Ma and the Cadillac Mountain granite at 419 + 2 Ma. These relations suggest that the Cadillac Mountain intrusive complex and the Cranberry Island series may be a deeply eroded, shallow-level pluton and its erupted equivalent, respectively. The volumes of the pluton and of the volcanic succession, the style of volcanism, and the compositional bimodality of the complex are reminiscent of caldera-style volcanism in terranes of crustal extension and thinning.

Siluro-Devonian Plutonic and Associated Volcanic Rocks of the Coastal Maine
Magmatic Province

Robert A. Wiebe, Franklin & Marshall College
R. A. Wobus, Professor of Geology

Abstracts Volume, Eighth Keck Research Symposium in Geology, 153-155 (1995) The plutonic and volcanic rocks that we studied occur along the coast of Maine between Bar Harbor and Jonesport. They are included within the Coastal Maine Magmatic Province (CMMP) (Hogan and Sinha, 1989), a province that contains more than 100 mafic and felsic plutons apparently emplaced over a time span from the Late Silurian to the Early Carboniferous. The bimodal character of this province is well established in both plutonic and volcanic rocks (Chapman, 1962; Seaman et al., in press), and there is widespread evidence for co-mingling between mafic and felsic magmas (Stewart et al., 1988; Chapman and Rhodes, 1992). Gravity studies (Hodge et al., 1982) indicate that many of the granitic plutons are thin, with gently dipping floors, and probably rest on mafic rocks similar to the interlayered diorite and gabbro that partly surround and dip beneath several of them. The plutons of the CMMP intrude a variety of metasedimentary and metavolcanic rocks in several fault-bounded, northeast-trending terranes featuring different stratigraphies and different structural and metamorphic histories (Williams and Hatcher, 1982). The ages and field relations of many of these plutons suggest that they postdate the main assembly of these lithotectonic terranes (Ludman, 1986). Hogan and Sinha (1989) suggested that some of the magmatism was related to rifting in a region of transtension along a transcurrent fault system.


Dehn Filling Hyperbolic 3-Manifolds

Colin C. Adams, Professor of Mathematics

Pacific Journal of Mathematics, Vol. 65, No. 2, 217-238 (1994) Define a complete family of parent (ancestor) manifolds to be a set of compact 3-manifolds such that every closed orientable 3-manifold can be obtained by one (or more) Dehn fillings of the manifolds in the family. In 1983, R. Myers proved that the set of 1-cusped hyperbolic 3-manifolds is a complete family of parent manifolds. We prove this result in a new way and then go on to prove:

Theorem 1.1. a) Let Vo be any positive real number. Then the set of 1-cusped hyperbolic 3-manifolds of volume greater than Vo is a complete family of parent manifolds. b) Let V1 be any positive real number. Then the set of 1-cusped hyperbolic 3-manifolds of cusp volume greater than V1 is a complete family of parent manifolds. c) The set of 2-cusped hyperbolic 3-manifolds containing embedded totally geodesic surfaces is a complete family of ancestor (actually grandparent) manifolds. d) For any positive integer N, the set of hyperbolic 3-manifolds, each of which shares its volume with N or more other hyperbolic 3-manifolds, is a complete family of ancestor manifolds.

As a corollary to Theorem 1b, we prove that there exists a complete family of parent manifolds such that at most one Dehn filling on each manifold in the family yields a manifold of finite fundamental group.

Tilings of Space by Knotted Tiles

Colin C. Adams, Professor of Mathematics

Mathematical Intelligencer, Vol. 17, No. 2, 41-51 (1995) It is demonstrated that Euclidean 3-space can be tiled with tiles, all congruent to a solid torus, knotted into the shape of any given knot. In fact, given any compact polyhedral submanifold of Euclidean 3-space with one boundary complement, it forms the topological type of a tile that can be used to tile Euclidean 3-space. These results generalize to Euclidean n-space, also.

Inhomogeneous Inequalities Over Number Fields

Edward B. Burger, Assistant Professor of Mathematics

Illinois Journal of Mathematics, 38: 452-470 (1994) Here we produce a number field analog of a theorem due to Khintchine regarding transference between homogeneous and inhomogeneous diophantine approximation. We also produce, in this general setting, a quantitative version of a theorem of Kronecker on inhomogeneous approximation. A qualitative number field analog of Kronecker's result was first given by Cantor. Our results also provide inhomogeneous analogs of results of Mahler. We examine these issues in the context of the ring of S-integers of a number field. Basic to our method are some new inequalities from the geometry of numbers over the associated adéle ring. In particular, new bounds are given for the inhomogeneous minimum.

Transcendence and Irrationality Measures

Edward B. Burger, Assistant Professor of Mathematics

Proceedings of the Seminar on the Theory of Numbers, Caen, France (1994) Let S be a non-empty set of non-negative integers and e > 0. Here we prove the existence of U2-numbers a such that for each n ΠS there exist infinitely many distinct rationals p/q so that |(a+n)2 - p/q| << q-q(1+e)log q and for each non-negative integer m oe S and rational p/q with q sufficiently large, q-q(1+e)log q << |(a+m)2 - p/q|, where the implied constants only depend upon e. Thus for n ΠS we have that (a+n)2 is Liouville and for m oe S we have effective measures of irrationality for (a+m)2.

Sur Les Quotients Partiels de U-Numbres Dans un Corps de So(',e)ries Formelles

Edward B. Burger, Assistant Professor of Mathematics

Comptes Rendus de L'Aco(',a)do(',e)mie des Sciences Paris (So(',e)rie I), 319: 421-426 (1994) Nous généralisons des résultats du premier auteur et T. Struppeck à un corps de séries de Laurent formelles. Soient A et B, deux sous ensembles de K[z]. Nous démontrons l'existence d'une infinité non dénombrable de U2-nombres (selon la classification de Mahler dans ce contexte), a dans K((1/z)), tels que les quotients partiels du développement en fraction continue sont tous dans A, tandis que (a + b)2 si car(K) != 2, ou (a +b) - 1/(a +b) si car(K) = 2 sont des nombres de Liouville pour chaque b dans B. De plus, nous contrôlons la distribution asymptotique des quotients partiels de ces nombres a.

Multicollinearity: A Tale of Two Non-parametric Regressions

Richard D. De Veaux, Assistant Professor of Mathematics
Lyle H. Ungar

Selecting Models from Data: AI and Statistics IV, 293-302 (1994) The most popular form of artificial neural network, feedforward networks with sigmoidal activation functions, and a new statistical technique, multivariate adaptive regression splines (MARS) can both be classified as nonlinear, nonparametric function estimation techniques, and both show great promise for fitting general nonlinear multivariate functions. In comparing the two methods on a variety of test problems, we find that MARS is in many cases both more accurate and much faster than neural networks. In addition, MARS is interpretable due to the choice of basic functions that make up the final predictive equation. This suggests that MARS could be used on many of the applications where neural networks are currently being used.

However, MARS exhibits problems in choosing among predictor variables when multicollinearity is present. Due to their redundant architecture, neural networks, however, do not share this problem, and are better able to predict in this situation. To improve the ability of MARS to deal with multicollinearity, we first use principal components to reduce the dimensionality of the input variables before invoking MARS. Using data from a polymer production run, we find that the resulting model retains the interpretability and improves the accuracy of MARS in the multicollinear setting.

Radial Basis Function Neural Networks for Process Control

Richard D. De Veaux, Assistant Professor of Mathematics
Lyle H. Ungar, Tom Johnson

CIMPRO Proceeding, 357-364 (1994) Radial basis function (RBFs) neural networks provide an attractive method for high dimensional nonparametric estimation for use in nonlinear control. They are faster to train than conventional feedforward networks with sigmoidal activation networks ("backpropagation nets"), and provide a model structure better suited for adaptive control. This article gives a brief survey of the use of RBFs and then introduces a new statistical interpretation of radical basis functions and a new method of estimating the parameters, using the EM algorithm. This new statistical interpretation allows us to provide confidence limits on predictions made using the networks.

Statistical Approaches to Fault Analysis in Multivariate Process Control

Richard D. De Veaux, Assistant Professor of Mathematics
Lyle H. Ungar, Johnathon M. Vinson

American Control Conference Proceedings, (1994) After a brief review of some statistical approaches to multivariate process control, we present a technique for determining root causes when information is available on likely out of control scenarios or fault types. We utilize linear dimension reduction techniques such as principal component analysis or partial least squares to limit the number of latent variables to study. While using historical in control data is important in establishing control means and limits, these data often have less structure for dimension reduction than do data which come from known fault types. If these latter data are available, the expanded data set can be analyzed for dimension reduction, using the in control data to set limits in the reduced set. When a sequence of points is then seen to be beyond the control limits, the distance to the nearest known fault type is measured. If the dimensions can be reduced to two, these can be plotted as well. The new problem is classified into one of the existing fault types when its distance to it becomes smaller than a pre-specified criterion. If it remains out of control, but fails to approach an existing fault type, a new fault paradigm is created. Our approach is demonstrated on a simulated chemical process.

A Statistical Basis for Using Radial Basis Functions for Process Control

Richard D. De Veaux, Assistant Professor of Mathematics
Lyle H. Ungar

American Control Conference Proceedings, (1995) Radial Basis Function (RBF) neural networks offer an attractive equation form for use in model-based control because they can approximate highly nonlinear plants and yet are well suited for linear adaptive control. We show how interpreting RBFs as mixtures of Gaussians allows the application of many statistical tools including the EM algorithm for parameter estimation. The resulting EMRBF models give uncertainty estimates and warn when they are extrapolating beyond the region where training data was available.

Invariants of Vector-Valued Bilinear and Sesquilinear Forms

Thomas Garrity, Associate Professor of Mathematics
Robert Mizner, Assistant Professor of Mathematics

Linear Algebra and Its Applications, 218: 225-237 (1995) First steps in the algebraic invariant theory of vector-valued bilinear and sesquilinear forms are made. In particular, explicit formulas for generators of all invariant rational functions for such forms are derived. These formulas, and certain analogs, have applications to the geometry of Riemannian submanifolds, distributions, and CR structures.

Simple Hybrid Systems

Stewart Johnson, Assistant Professor of Mathematics

International Journal of Bifurcations and Chaos, Vol. 4, No. 6, 1655-1665 (1994) A hybrid system is one that can instantaneously switch between a number of phase portraits. Switching occurs when trajectories hit prescribed switching curves. This type of system is highly applicable to digital controls such as robotic controls. A working definition of such a system is given, a method for stabilizing periodic orbits is given, and several examples are explored.

Regularized Semiclassical Radial Propagator for the Coulomb Potential

Robert S. Manning, Visiting Assistant Professor of Mathematics
Gregory S. Ezra

Physical Rev. A, 50: 954 (1994) We derive a regularized semiclassical radial propagator for the Coulomb potential, a case for which standard approaches run into well-known difficulties associated with a non-Cartesian radial coordinate and a potential singularity. Following Kleinert [Path Integrals in Quantum Mechanics, Statistics and Polymer Physics (World Scientific, Singapore, 1990)], we first perform a quantum-mechanical regularization of the propagator. The semiclassical limit is then obtained by stationary phase approximation of the resulting integrals. The semiclassical propagator so derived has the standard Van Vleck-Gutzwiller form for the radial Coulomb problem with a potential correction (Langer modification) term included. The regularized semiclassical propagator is applied to compute the autocorrelation function for a Gaussian Rydberg wave packet.

Invariants of Vector-Valued Bilinear and Sesquilinear Forms

Robert Mizner, Assistant Professor of Mathematics
Thomas Garrity, Associate Professor of Mathematics

Linear Algebra and Its Applications, 218: 225-237 (1995) First steps in the algebraic invariant theory of vector-valued bilinear and sesquilinear forms are made. In particular, explicit formulas for generators of all invariant rational functions for such forms are derived. These formulas, and certain analogs, have applications to the geometry of Riemannian submanifolds, distributions, and CR structures.

Paired Calibrations Applied to Soap Films, Immiscible Fluids, and Surfaces or Networks Minimizing Other Norms

Frank Morgan, Professor of Mathematics
Gary Lawlor

Pacific Journal of Mathematics, 166: 55-83 (1994) We prove cones such as the cone over the tetrahedron minimizing in a context that applies to soap films, immiscible fluids, shortest networks, and more general norms than area. The proof is direct, using a new kind of calibration.

Soap Bubbles in R2 and in Surfaces

Frank Morgan, Professor of Mathematics

Pacific Journal of Mathematics, 165: 141-155 (1994) Planar soap bubbles consist of arcs of circles meeting in threes at 120[[ring]] angles. This paper fills a gap in the literature and provides a simplified illustration of the rather technical methods of Almgren.

Surfaces Minimizing Area Plus Length of Singular Curves

Frank Morgan, Professor of Mathematics

Proc. AMS, 122: 1153-1161 (1994) The first existence and regularity results on surfaces minimizing area plus length of singular curves, as in energy-minimizing interfaces in materials.

The Isoperimetric Theorem for General Integrands

Frank Morgan, Professor of Mathematics
John E. Brothers

Michigan Mathematical Journal, 41: 419-431 (1994) A new, simple, general proof that the Wulff crystal minimizes surface energy for given volume.

Clusters Minimizing Area Plus Length of Singular Curves

Frank Morgan, Professor of Mathematics

Math Annalen, 229: 697-714 (1994) The first existence and regularity results for clusters of prescribed volumes in R3 minimizing area plus length of singular curves, as in metals.

New Undergraduate Research Prize

Frank Morgan, Professor of Mathematics

Notices AMS, (January 1995) A news report on the new AMS-MAA-SIAM undergraduate research prize.

Geometric Measure Theory: a Beginner's Guide

Frank Morgan, Professor of Mathematics

Academic Press, second edition (1995) An easy-going, illustrated introduction for the newcomer to this fast-growing and somewhat technical field. The second edition includes a new chapter on soap bubble clusters.

On Quotients of Nonsingular Actions Whose Self-Joinings are Graphs

Cesar E. Silva, Associate Professor of Mathematics
Dave Witte, Assistant Professor of Mathematics

International Journal of Mathematics, Vol. 5, No. 2 , 219-237 (1994) We study the notions of minimal self-joinings (MSJ) and graph self-joinings (GSJ) (analogous to simplicity in the finite measure preserving case) for nonsingular actions of locally compact groups. We show that for a nonsingular action of a group G with MSJ, every quotient comes from a closed subgroup of the center of G whose action is totally non-ergodic. Thus, totally ergodic nonsingular flows with MSJ are prime. We then show an analogous result to Veech's theorem, namely that for a nonsingular action of a group G with GSJ, every quotient comes from a locally compact subgroup of the centralizer whose action is totally non-ergodic.


On the Reduction of Quantum Entropy by Reversible Extraction of Classical Information

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

Journal of Modern Optics, 41, 2307 (1994) We inquire under what conditions at least some of the information in a quantum signal source, i.e., a set of pure states [[arrowvertex]][[psi]]a> emitted with probabilities Pa, can be extracted in classical form by measurement, leaving the quantum system with less entropy than it had before, but retaining the ability to regenerate the source state exactly from the classical measurement result and the after-measurement state of the quantum system. We show that this can be done if and only if the source states fall into two or more mutually orthogonal subsets.

A `Pretty Good' Measurement for Distinguishing Quantum States

Paul Hausladen `93 and William K. Wootters, Professor of Physics

Journal of Modern Optics, 41, 2385 (1994). We address the problem of extracting information from a single quantum system known to be in one of several possible states. In the generic case, it is notoriously difficult to find the optimal measurement, that is, the measurement that provides the most possible information about the system's state. We consider a simple general prescription for a measurement that is typically not optimal but appears to be quite good. It seems to be particularly good when the states to be distinguished are equally likely and almost orthogonal.

Sending Classical Bits via Quantum Its

Paul Hausladen `93, Benjamin Schumacher, Michael Westmoreland, and William K. Wootters, Professor of Physics

Fundamental Problems in Quantum Theory: A Conference Held in Honor of Professor John A. Wheeler, D.M. Greenberger and A. Zeilinger, eds. (New York Academy of Sciences, 1995) We imagine a communication scenario in which the sender, Alice, tries to convey a classical message to the receiver, Bob, using only a restricted set of states of a quantum system, e.g., a fixed set of polarization states of a photon. It has been known for some years that the amount of information Alice can convey per particle in such circumstances is bounded above by the entropy of the ensemble of signal states. We find that at least for photon polarizations, this bound can be approached arbitrarily closely by letting Bob make coherent measurements on many photons at once. We conjecture that this result generalizes to arbitrary quantum systems.

Precise Test of Electroweak Theory from a New Measurement of Parity
Nonconservation in Atomic Thallium

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

Physical Rev. Letters 74, 2657 (1995). We report a new measurement of parity nonconserving optical rotation near the 1.283 um, 6P1/2 - 6P3/2 magnetic dipole transition in thallium. We find the ratio of the PNC E1 amplitude to the M1 amplitude to be R = (-14.68 +/- 0.17) x 10-8, which within the present uncertainty of atomic theory yields the thallium weak charge Qw (205T1) = -114.2 +/- 3.8 and the electroweak parameter S = -2.2 +/- 3.0. Separate measurements of the F = 1 and F = 0 ground-state hyperfine transitions yield R1 - R0 = (0.15 +/- 0.20) x 10-8, which limits the size of nuclear spin-dependent PNC in T1.

The Invention of Space

David Park

Art, The Integral Vision, Saraswati, Malik, and Khanna, eds. (Printworld, New Delhi, 1994) Geometry draws its diagrams on a piece of paper, which in a sense represents a space in which the figures float but is actually a thing on which they sit. This chapter describes the discovery of empty space as something to be dealt with in its own right in two great inventions: perspective drawing in the fifteenth century and Kepler's planetary orbits in the seventeenth. In both cases one situated a building or a human figure or a planet in a way determined by mathematical laws in a space that otherwise had nothing in it. If one thinks of Persian miniature painting in which figures are stuck to a landscape or Copernican astronomy in which planets are stuck to a huge machine one sees that something radically new has been invented.


Do Children Use the Big Five, Too?
Content and Structural Form in Children's Descriptions of Personality.

Eileen M. Donahue, Assistant Professor of Psychology

Journal of Personality, 62, 45-66 (1994). Free personality descriptions generated by 11-year olds in the Role Construct Repertory Test (Kelly, 1955) were content analyzed. The children's personality constructs were coded according to structural form (e.g., Habits, Preferences, Traits) and Big Five personality content domain (e.g., Agreeableness, Conscientiousness). Findings showed that the children generated constructs from all of the Big Five personality domains. Agreeableness constructs were used most frequently, replicating the prevalence of that domain in studies of adult trait attribution (Peabody & Goldberg, 1989). However, in contrast to adults, less than half of the children's Big Five constructs were expressed as personality traits. The children's use of structural forms varied systematically with the personality domain they were describing. Target likability and age were also found to be related to the personality domains and structural forms of the children's constructs.

One Personality, Multiple Selves: Integrating Personality and Social Roles.

Eileen M. Donahue, Assistant Professor of Psychology, and
B. W. Roberts

Journal of Personality, 62, 199-218 (1994). How do people maintain multiple, role-specific self-conceptions as well as a consistent sense of self? In a sample of middle-aged women, we examined three issues: (a) the way in which people view themselves as both different and similar across role identities (e.g., parent, friend, worker), (b) how role-specific self-conceptions and general self- conceptions are related, and (c) the merits of predicting role-specific criteria from role- specific and general self-conceptions. Results showed that subjects' self-conceptions were specific to role contexts, yet highly correlated across those same role contexts. In addition, role-specific self-conceptions were more similar to the general self-concept for roles with which the individual was more satisfied. Finally, as predicted from the bandwidth-fidelity trade-off, ratings of the general self correlated moderately with outcomes across all role domains, whereas ratings of role-specific self-conceptions correlated strongly with outcomes for the same role, but not for other roles.

Who Do You Think You Are?
Explore Your Many-Sided Self with the Berkeley Personality Profile.

Eileen M. Donahue, Assistant Professor of Psychology, and K. Harary

San Francisco: Harper San Francisco.(1994). This book introduces the lay reader to the Big Five model and to the multifaceted nature of the self, and provides a means for the reader to explore numerous facets of his or her own personality -- public and private sides of the self-concept, ideal and feared "possible selves," identities associated with various social roles, and perceptions of his or her personality as seen through the eyes of peers, family members, and coworkers -- all within the unifying framework, or common language, of the Big Five. The test items used are from the Big Five Inventory, (John, Donahue, & Kentle, 1991) and the interpretation of results is guided by extensive research with that instrument, based on the responses of over 10,000 individuals.

Judging Others in the Shadow of Suspicion

Steven Fein, Assistant Professor of Psychology, et al.

Motivation and Emotion, 18, 167-198. Previous research has found that when perceivers have reason to be suspicious of the motives underlying an actor's behavior, they are likely to draw inferences about the actor's true disposition that reflect a relatively sophisticated style of attributional processing. The present research was designed to examine some of the negative consequences that suspicion can have on perceivers' judgments. In each of the three studies reported, some subjects were made suspicious about the motives of an actor on the basis of contextual information surrounding the actor's behavior, rather than the behavior itself. The results of these studies suggest that, particularly when perceivers believe that the actions or motives of the actor could affect them, suspicion may cause perceivers to see the actor in a more negative light, even if the perceivers are not convinced that the actor's behavior was indeed affected by ulterior motives.

Differential Behavioral Effects of the Neuroactive Steroid Allopregnanolone on Neonatal Rats Prenatally Exposed to Alcohol

Betty Zimmerberg, Associate Professor of Psychology, Peggy Drucker `94, and Jacqueline M. Weider `91

Pharmacology Biochemistry and Behavior, 51(2,3), 463-468 (1995). The effects of prenatal alcohol exposure on the behavioral response to the neuroactive steroid allopregnanolone (3u-hydroxy-5u-pregnan-20-one) were investigated in neonatal rats. Two behaviors were assessed: retention of an odor conditioning task and production of ultrasonic vocalizations after brief maternal separation. Subjects from one of the three prenatal conditions (lab chow, alcohol, or pair-fed) received either no injection or an i.c.v. injection of vehicle or one of three doses (1.25 ug- 5.0 ug) of allopregnanolone either 20 min prior to or immediately after training in an appetitive odor association paradigm. Retention was assessed one hour later in a two-choice odor preference chamber. Post-training injections of allopregnanolone caused a dose-dependent impairment in retention in the odor task, but there was no differential sensitivity to allopregnanolone in the alcohol-exposed offspring. All pre-training injections, including the vehicle, resulted in impairments in retention on the task, suggesting an impairment due to stress but not due to allopregnanolone. Allopregnanolone also reduced ultrasonic vocalizations after brief maternal separation in all subjects in a second experiment, but alcohol-exposed offspring displayed a dose-dependent shift to the right in their anxiolytic response to this neurosteroid. This decreased sensitivity suggests that prenatal alcohol exposure may cause a decrease in the density or affinity of the GABA receptors involved in stress response, but not cognitive processes, at this age.

The Development of ß1-Adrenoreceptors in Brown Adipose Tissue
Following Prenatal Alcohol Exposure

Betty Zimmerberg, Associate Professor of Psychology, Jacqueline M. Weider `91, et al

Alcohol, 12(1), 71-77, 1995. Prenatal alcohol exposure delays the development of thermoregulation in newborn rats. Newborns generate heat by the sympathetic nervous system's activation of non-shivering thermogenesis in brown adipose tissue (BAT). In this study, the effect of prenatal alcohol exposure on the development of the beta-adrenergic receptor system of BAT was investigated by assessing the number and pharmacological properties of beta-adrenergic receptors in BAT in 1, 5, 10, and 20 day old offspring. Pregnant dams were given either a liquid diet with 35% of the calories derived from alcohol, a liquid diet without alcohol to control for any effects of the liquid diet administration, or ad libitum food and water. Offspring from the alcohol prenatal treatment group had a greater number of beta1 adrenergic receptors compared to offspring from both from the pair-fed and lab chow control groups, which did not differ from each other. The greater number of receptor sites in 5 day old subjects suggests that the number of binding sites in alcohol-exposed BAT cells continues to rise due to the absence of sufficient neurotransmitter, and perhaps reflects a delay in the arrival of sympathetic nervous system neurons. During the second and third postnatal weeks, when NE concentrations are rising and reaching asymptotic levels, the number of beta1 adrenergic receptors in BAT of control subjects is decreasing. This expected compensatory "downregulation" response in receptor concentration was not seen in BAT from subjects exposed to alcohol prenatally. These findings may have important implications for understanding the effects of prenatal alcohol exposure on developing plasticity in the peripheral nervous system.

Two Investigations of "Female Modesty" in Achievement Situations

Laurie Heatherington, Associate Professor of Psychology, Alicia Ahn `92, Heather Brown `93, Camille Preston `93, et al.

Sex Roles, 29(11-12), 739-754 (1993). (Omitted from 1993-94 Report of Science) Two experiments examined motivations underlying the common finding that females present themselves more modestly than males in achievement situations. In Study 1, 388 first-year college students, primarily European-Americans, predicted their first semester grade point averages (GPAs) in one of 3 public and 2 private conditions, which varied the salience of modesty concerns and/or concerns about the others' feelings. In the public conditions combined, but not in the private conditions, women's predictions were lower than men's, although there were no gender differences in actual GPA. The public condition in which the others' feelings and modesty concerns were made salient accounted for this difference between men and women. In Study 2, 230 first-year college students predicted their first-semester GPAs in private, in public to a "nonvulnerable" other, or in public to a "vulnerable" other (someone who supposedly had earned a low GPA). Women's estimates were lower than men's in the latter condition only and lower than their estimates in the other conditions. These results suggest that relational motivations, rather than a simple lack of self-confidence or modesty alone, are a factor in gender differences in self-presentation of achievement.

La Pragmatica de la Communicacion en Terapia Familiar
(Pragmatics of Relational Control in Family Therapy)

Laurie Heatherington, Associate Professor of Psychology and M. L. Friedlander, SUNY-Albany

Cuadernos de Terapia Familiar, 23, 59-78 (1993). (Omitted from 1993-94 Report of Science) Este artículo describe nuestro programa de investigación en curso sobre la dinámica del control de la comunicación relacional en terapia familiar, una tarea que surge de la tradición de Bateson (1936/1958), Haley (1963), y Watzlawick, Beavin y Jackson (1967) entre otros. Describimos el desarrollo y las propiedades psicométricas desl Sistema de Codificación del Control de la Comunicación Relacional Familiar (Family Relational Communication Control Coding System), un sistema de codificación observacional de los patrones de control relacional verbales y no verbales en familias y otros grupos. Se resumen los estudios que (a) describen la dinámica del control relacional en las entrevistas de terapia familiar y (b) que relacionan esta dinámica con el proceso de cambio terapéutico. Por último, ofrecemos un resumen de lo que se ha aprendido y de lo que todavia tenemos que aprender, es decir, sugerencias para la investigación futura.

Commitment to Engage: A Change Event in Family Therapy

Laurie Heatherington, Associate Professor of Psychology, Ben Johnson `91, et al.

Journal of Counseling Psychology, 41, 438-448 (1994). In response to the call for researchers to identify components of family treatment that are common across theoretical approaches (e.g., A. S. Gurman, 1988), a qualitative analysis was undertaken of an important change event in family treatment: sustaining engagement (SE). Using R. C. Bogdan and S. K. Biklen's (1992) modified analytic induction method, a sample was identified of successful SE events - that is, therapeutic episodes in which family members moved from disengagement with each other to sustained engagement on a problem-solving task. Videotapes of 33 sessions were scrutinized to develop and refine the operational definition of disengagement and sustained engagement. After two reviewers independently verified the selection of 8 SE events, a qualitative comparison was conducted of the interpersonal dynamics in the 4 successful versus the 4 unsuccessful events. The resulting conceptual model of the SE change process is described, followed by suggestions for continued research on this therapeutic event.

What We Do and Don't Know About the Process of Family Therapy

Laurie Heatherington, Associate Professor of Psychology, et al.

Journal of Family Psychology, 8, 390-416 (1994). Despite convincing outcome evidence and the popularity of family therapy, little is known about how interpersonal change actually comes about in this context. To synthesize and integrate what is known and to offer recommendations for future, clinically relevant research, all published process studies on family therapy were reviewed. Included were naturalistic studies of conjoint treatment in which the focus was the in-session verbal behavior of the participants or their self-reported perceptions of actual interactions. Dating from 1963, 36 studies met the inclusion criteria. The review was organized according to 3 hierarchically ordered levels of in-session processes (S. Greenberg, 1986): observations of (a) speech acts, followed by studies of (b) important incidents or change episodes and (c) the therapeutic relationship. The implications of what is "known" are followed by a discussion of what is not known and suggested directions for future research.

Unrealistic Optimism: Self-Enhancement or Person Positivity?

Professor Saul M. Kassin, et al.

Personality and Social Psychology Bulletin, 21, 820-832 (1995). Researchers interested in unrealistic optimism disagree as to whether the phenomenon reflects self-enhancement or person positivity. Past research in this area has utilized a paradigm that confounds the self vs. other dimension with the individual vs. aggregate dimension, thus making it difficult to determine which alternative is correct. Three studies were designed to discover whether people are unrealistically optimistic only for their own futures or whether they are unrealistically optimistic for the future of any individual. Studies 1 and 2 revealed that, in comparison to an aggregate of same-sex peers, participants were unrealistically optimistic for their own and a close friend's futures, but not for the futures of non-self-relevant persons. Study 3 employed unconfounded measures and demonstrated that, in comparison to other individual social objects, participants continued to be unrealistically optimistic for their own futures. These studies suggest that unrealistic optimism is primarily a form of self-enhancement rather than person positivity bias. Implications for theory and research on unrealistic optimism and the nature of the self are discussed.

Deja Vu All Over Again: Elliott's Critique of Eyewitness Experts

Professor Saul M. Kassin, et al

Law and Human Behavior, 18, 203-210 (1994). In a recent article, Elliott (1993) used the results of our survey of eyewitness experts (Kassin, Ellsworth, & Smith, 1989) to attack the testimony of psychologists who testify in this area. There are two shortcomings to Elliott's critique. First, he merely echoes past comments concerning the standards by which experts should conduct their affairs. Second, and more serious, he misrepresents both the eyewitness research literature and the behavior of expert witnesses in the courtroom. These latter issues are addressed in turn.

Imagining the Outcome of Pretend Transformations:
Assessing the Competence of Normal Children and Children with Autism

Robert D. Kavanaugh, Professor of Psychology, and Paul L. Harris, University of Oxford

Developmental Psychology, 30(6), 847-854 (1994). Children's grasp of make-believe transformation was studied. In Experiment 1, children saw an adult enact a pretend change (e.g., sprinkling pretend talcum powder over a toy cat). They indicated the pretend outcome by choosing between a picture depicting no change (e.g., cat without talcum powder on its body) and a picture depicting the pretend change (e.g., cat covered with talcum powder). Older children (M=29 months) chose correctly, but younger children (M=21 months) did not. A similar age change emerged in Experiment 2 despite the addition of a picture of an irrelevant transformation. Experiment 3 showed that children with autism can imagine pretend transformations. Implications for children's imagination and the autistic syndrome are discussed.

The Mind of a Child

Review by Robert D. Kavanaugh, Professor of Psychology

Contemporary Psychology, 39 (8), 834-837, 1994

False Alarm: A Reply to Over and Evans

Kris N. Kirby, Assistant Professor of Psychology

Cognition, 52(3): 245-250 (1994)

Preference Reversals Due to Myopic Discounting of Delayed Reward

Kris N. Kirby, Assistant Professor of Psychology
R. J. Herrnstein, Harvard University

Psychological Science, 6(2): 83-89 (1995) A basic stationarity axiom of economic theory assumes stable preference between two deferred goods separated by a fixed time. To test this assumption, we offered subjects choices between delayed rewards, while manipulating the delays to those rewards. Preferences typically reversed with changes in delay, as predicted by hyperbolic discounting models of impulsiveness: Of 36 subjects, 34 reversed preference from a larger, later reward to a smaller, earlier reward as the delays to both rewards decreased. We conclude that the stationarity axiom is not appropriate in models of human choice.

Tacrine in the Treatment of Alzheimer's Disease

Paul R. Solomon, Professor of Psychology and William Pendlebury

Directions in Psychiatry, 14, 2-8 (1994) In this paper, 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. Studies supporting tacrine's efficacy in combating Alzheimer's disease are cited, including a high-dose, 30-week study that indicated patients treated with tacrine (160 mg) showed statistically significant and clinically observed improvements on objective cognitive tests, clinician and caregiver global evaluations, and quality-of-life assessments.

It is not possible to predict which patients will benefit from tacrine. Moreover, tacrine is not a "cure." But if the symptoms of Alzheimer's disease can be stabilized over relatively long periods and if there is no decline over 6 months, a successful outcome can be achieved. Although tacrine seems to offer symptomatic relief by increasing the level of neurotransmitter depleted in Alzheimer's disease, it does not affect the underlying disease process. Also, despite its being a relatively safe drug, tacrine can cause cholinomimetic gastrointestinal side effects and elevations in aspartate aminotransferase.

Tacrine should be used in the context of an overall program of clinical management, which can include other medications as indicated (such as anxiolytic, antidepressant, and antipsychotic agents). Research into genetic issues may lead to new treatments and preventive strategies.

Strategies for Developing Animal Models of Neurotoxicant-induced Neurodegenerative Disorders: Parallel Studies of Learning and Memory in Animals and Humans

Paul R. Solomon, Professor of Psychology, Mary Ellen Groccia-Ellison, et al.

In: Nonneman, A. J. & Woodruff, M. L. (Eds),

Neurotoxic Models of Neurological Disorders, New York: Plenum Press (1994). We have attempted in this chapter to demonstrate how the model systems approach to the neurobiology of learning and memory might be useful in understanding memory loss associated with neurotoxicant-induced neuro-degenerative disorders. We have emphasized the idea that for an animal model to be useful, it is important to be able to generalize from animals to humans. One way to accomplish this is to use a model system in which the identical behavior can be studied in both humans and animals. Using this approach, if various manipulations produce similar effects in both species, the risks inherent to cross-species generalization would seem to be reduced. We have presented data from eyeblink conditioning in humans and rabbits to suggest that this is the case. We have shown that a number of manipulations and conditions produce similar effects in both species including (1) brain lesions to the cerebellum and hippo-campus, (2) aging, and (3) scopolamine administration. We have also provided evidence regarding the effects of a known neurotoxicant - aluminum - on conditioning in rabbits and suggested how we might study aluminum-exposed humans. Collectively, these data suggest that using relatively simple systems in which both the behavior and neurobiology are well understood, and in which identical behaviors can be studied in humans and animals, may eventually be helpful in establishing hypotheses about the etiology and pathogenesis of neuro-degenerative disorders.

Age-Related Deficits in Retention of the Classically Conditioned Eyeblink Responses in Rabbits.

Paul R. Solomon, Professor of Psychology, Christine Barth `92, Mika Wood `93, Eric Velasquez `88, Mary Ellen Groccia-Ellison, and Bo Yi Yang

Behavioral Neuroscience, 109, 18-23 (1995). Young and aged rabbits underwent classical conditioning of the nictitating membrane response (NMR) to a tone conditioned stimulus (CS) and a corneal airpuff unconditioned stimulus (UCS) for 18 consecutive days. Rabbits were then returned to their home cages for a 90-day period in which they received no further conditioning, but they were handled daily. On Day 91 they underwent retention testing during which the CS alone was presented 20 times. This was immediately followed by reacquisition in which the CS and UCS were again paired for 100 trials. Reacquisition was repeated on the following day. As in previous studies, aged rabbits acquired the conditioned response (CR) more slowly than young rabbits; however, by the end of acquisition, both groups reached similar asymptotic levels. Retention of the CR was significantly lower for aged than young rabbits. Reacquisition was also retarded in aged vs. young rabbits. Nonassociative factors, such as sensitivity to the stimuli or general health, could not account for these differences. Data are discussed in terms of using retention of the conditioned eyeblink response as a model system for studying age-related memory deficits.

Classical Conditioning in Patients with Alzheimer's Disease: A Multi-Day Study

Paul R. Solomon, Professor of Psychology, Marissa Brett `92, Mary Ellen Groccia-Ellison, Catherine Oyler `93, Marie Tomasi `93, and William Pendlebury

Psychology and Aging, 10(2) (1995). Previous studies demonstrated that patients with Alzheimer's disease (AD) do not acquire the classically conditioned eyeblink response. These studies, however, were only tested over a single conditioning session and, hence, raise the question of whether AD patients are capable of acquiring the response if sufficient training is given. This question may be of some importance because whether AD patients can ultimately acquire the response has implications for the underlying neurobiological deficit in disrupted conditioning in AD. The present study tested AD patients and age-matched controls over 4 days. As in previous studies, AD patients performed significantly worse than controls on Day 1, but by Day 4, they were not significantly different from controls. Subsequent testing indicated that these effects were not due to nonassociative variables such as changes in sensitivity to stimuli or disruption of the motor response. Also, it was reported that neither AD patients nor controls showed any evidence of acquisition in an explicitly unpaired paradigm, suggesting that neither pseudoconditioning nor sensitization is contributory. Data are discussed in terms of the possible role of the hippocampus in mediating conditioning deficits in AD patients.

What are the Best Strategies for Understanding Hippocampal Function?

Paul R. Solomon, Professor of Psychology, and Bo Yi Yang

Behavioral and Brain Sciences, 17, 447-448 (1994).

Tacrine and Lecithin in the Treatment of Alzheimer's Disease

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

British Medical Journal, 308, 1506 (1994).


Modified by: bbabcock
Modification Date: December 13, 1995