FACULTY PUBLICATIONS

We have compiled a large sample of O, Ne, S, Cl, and Ar abundances that have been determined for 85 Galactic planetary nebulae in a consistent and homogeneous manner using spectra extending from 3600 to 9600 Å. Sulfur abundances have been computed using the near-IR lines of [S III] 9069 Å, 9532 Å along with [S III] temperatures. We find average values, expressed logarithmically with a standard deviation, of log (S/O) = -1.91 ± 0.24, log(Cl/O) = -3.52 ± 0.16, and log(Ar/O) = -2.29 ± 0.18, numbers consistent with previous studies of both planetary nebulae and H II regions. We also find a strong correlation between [O III] and [S III] temperatures among planetary nebulae. In analyzing abundances of Ne, S, Cl and Ar with respect to O, we find a tight correlation for Ne-O, and loose correlations for Cl-O and Ar-O. All three trends appear to be co-linear with observed correlations for H II regions. S and O also show a correlation, but there is a definite offset from the behavior exhibited by H II regions and stars. We suggest that this S anomaly is most easily explained by the existence of S+3, whose abundance must be inferred indirectly when only optical spectra are available, in amounts in excess of what is predicted by model-derived ionization correction factors in PNe. Finally, for the disk PNe, abundances of O, Ne, S, Cl and Ar all show gradients when plotted against Galactocentric distance. The Slopes are statistically indistinguishable from one another, a result which is consistent with the notion that cosmic abundances of these elements evolve in lockstep.

We report the first results of a Cycle 12 Hubble Space Telescope SNAP program imaging the C III] 1909 Å lines in planetary nebulae (PNe) and extragalactic H II regions using WFPC2 with the F185W filter. To date (2004 June), four PNe (NGC 6210, NGC 6720, NGC 6826 & NGC 7662) and four H II regions (LMC N160A, SMC N81, NGC 2363 and IZw18) have been observed.

Using continuum imagery of the nebulae made with HST WFPC2 and the knowledge of the UV spectra of regions in the nebulae from archival HST FOS/STIS or IUE data, the UV continuum contribution to the F185W images is calculated and subtracted to give images of the nebulae in the emission of C III] 1909 Å. These are compared to similarly processed HST WFPC2 images of the nebulae in other emission lines, such as [O III] 5007 Å and H/Hß, to study the ionization structure of C+2 compared to O+2 and H+, for example. The objectives of the research include: (a) studying the effects that nebular variations in density, temperature and dust content have on the observed F(1909 Å)/ F(5007 Å) line ratio across the nebulae, (b) studying the co-spatiality of the C+2 and O+2 ionization structure, and (c) evaluation of the accuracy of using observations of the integrated F(1909 Å)/F(5007 Å) line ratio in nebulae for determining the C+2/O+2 ratio and the total C/O abundance ratio in PNe and H II regions.

This research is supported in part by AURA/STScI grants HST-GO-09740 to Rice University, University of Oklahoma, and Williams College.

One of the perennial questions for teachers of astronomy survey courses is whether to use the magnitude system in general use by amateur and professional astronomers, or whether to give all star brightnesses in powers-of-ten notation. The problem goes to the goals of the course and to the philosophy of history, liaison with others, and course content held by the professor. It also leads to discussions of the mathematical and conceptual levels intended.

Centimeter and millimeter-wave observations of a molecular cloud at the extreme outer edge of the Galactic disk (kinematic galactocentric distance: 28 kpc) are presented. We detected CO, 13CO, 18CO, CS, CN, SO, HCN, HNC, C2H, HCO+, H13CO+, HCS+, NH3, H2CO, C3H2 and CH3OH, while C17O, C34S, SiO, SiS, N2H+, DCN, DNC, DCO+, SO2 and HC3N remained undetected. From the NH3 and H2CO data, a kinetic temperature of Tkin = 20 K and a density of n(H2) = 5x103 cm-3 are derived. Nitrogen-bearing molecules show, when detected, only weak lines. Commonly strong line emitters such as N2H+ and HC3N were not seen. Using a numerical network including 5300 chemical reactions we determined that N is depleted by approximately 24 times, and the metallicity is reduced by a factor of five (similar to dwarf irregular galaxies or damped Lyman alpha systems) relative to the solar neighborhood. These unusual abundances are probably the result of the infall of halo gas enriched in O, C, and S from a burst of massive star formation in the Galactic halo shortly after the Milky Way was formed. This activity would have produced both O and S, which are produced by massive stars; C, which is produced by massive and intermediate mass stars; but less N abundance because the secondary element N is produced primarily from low mass stars. Thus the edge cloud probably results from in-falling halo gas from the early Galaxy that was not significantly processed during the last 10 Gyr and provides a new way to understand the origin of the Galactic disk. Our observations of the early Galactic disk abundances will constrain models of nucleosynthesis, Galactic chemical evolution, and astrochemistry.

We present observations of a 10-Gyr-old molecular cloud at the outer edge of the Galactic disk (28 kpc). We detected CO, 13CO 18CO, CS, CN, SO, HCN, HNC, HCO+, CH3OH, HCS+, H2CO, C2H, C3H2, and NH3 but we did not detect CO+, N2H+, DCN, HC3N, C34S, SiO, SiS, C17O, or SO2. The NH3, H2CO, and CS abundances indicate that T = 20 K and n = 5x103 cm–3. The N-containing molecules were weak and we did not detect the usually strong N2H+ or HC3N lines. Using our 5300 chemical reaction model we calculate that the N is depleted in this cloud by about 3x and this cloud has a lower metallicity (similar to dwarf irregular galaxies or damped Lyman alpha systems) and a lower cosmic-ray ionization rate possibly resulting from the infall of halo gas enriched in O, C, and S from a burst of massive star formation in the Galactic halo shortly after the Milky Way was formed. This activity would have produced both O and S which are produced by massive stars; C which is produced by massive and intermediate mass stars; but less N abundance because the secondary element N is produced primarily from low mass stars

Historically, the visual manifestation of the “Black Drop effect,” the appearance of a band linking the solar limb to the disk of a transiting planet near the point of internal tangency, had limited the accuracy of the determination of the Astronomical Unit and the scale of the Solar System in the 18th and 19th centuries. This problem was misunderstood in the case of Venus during its rare transits due to the presence of its atmosphere. We report on observations of the 15 November 1999 transit of Mercury obtained, without the degrading effects of the Earth’s atmosphere, with the Transition Region and Coronal Explorer spacecraft. In spite of the telescope’s location beyond the Earth’s atmosphere, and the absence of a significant mercurian atmosphere, a faint Black Drop effect was detected. After calibration and removal of, or compensation for, both internal and external systematic effects, the only radially directed brightness anisotropies found resulted from the convolution of the instrumental point-spread function with the solar limb-darkened, back-lit, illumination function. We discuss these effects in light of earlier ground-based observations of transits of Mercury and of Venus (also including the effects of atmospheric "seeing”) to explain the historical basis for the Black Drop effect. The methodologies we outline here for improving upon transit imagery are applicable to ground-based (adaptive optics augmented) and space-based observations of the 8 June 2004 and 5-6 June 2012 transits of Venus, providing a path to achieving high-precision measurements at and near the instants of internal limb tangencies.

What should non-major and school-level students learn about astronomy? The current trend in Physics Education Research, now being translated to Astronomy Education Research, is that "less is more." As a result, there may be little time for modern topics or there may be a judgment that these topics are too abstract to teach.

Yet NASA’s Great Observatories and other missions have vital and interesting Education and Public Outreach programs. Through the Web, through distribution of CD-ROM’s and other media, and through a variety of materials and activities these programs provide not only reports on current research but also substantial background information.

To explore the contemporary question of what we professional astronomers think we should be communicating to students at all levels, I have invited both scientists and public information officers of the Hubble Space Telescope, the Chandra X-ray Observatory, and the Space Infrared Telescope Facility to discuss the importance and the methodologies of their Education and Public Outreach programs.

We used the observations of the transits of Mercury of 1999 and 2003 taken with NASA’s Transition Region and Coronal Explorer (TRACE) solar spacecraft. For the 1999 Mercury transit, for which data were acquired with the highest digital fidelity available for TRACE, we detected a black-drop effect, in spite of the facts that we were observing from outside the Earth’s atmosphere and that Mercury has no significant atmosphere. We were able to show that the Mercury black-drop effect comes from a convolution of the instrument’s point-spread function and the solar limb darkening. By implication, we should be able to explain Venus’s black-drop effect in a similar way. It has long been known that Venus’s black-drop effect is too large to come from Venus’s atmosphere.

I describe an actual staircase, constructed by a carpenter out of wood, with spacing corresponding to the energy levels in the Bohr atom. I show how the spectral lines of the Balmer series result from transitions between these levels. I describe how I use this demonstration in class.

Successive Medici "courts" developed the nascent interest in astronomy of Cosimo de’ Medici, the dynasty’s founder. The "Pater Patriae" celebrated the play on words in his name (cosmos) and, according to Vespasiano da Bisticci, learned "astrology" from Paolo Toscanelli, the astronomer and probable advisor of the Old Sacristy’s scarsella dome fresco. This fascination took root at the papal court where, under two Medici Popes, Raphael, Sebastiano del Piombo, and Leonardo daVinci engaged in astronomical pursuits.

As the visual rhetoric of their patronage demonstrates, the Medici Grand Ducal courts nurtured developments in the sciences, adding to the family’s glory and underlining its enlightened sponsorship of the arts and sciences (considered handmaidens). Even though astrology and astronomy became separated under their aegis, astronomical elements first occur in astrological contexts, e.g. the court dialogue between art and nature (the Studiolo). Cosimo I’s thematic propaganda was saturated with astrological symbolism, although his interest in geography found concrete expression in the Salla delle Carte Geografiche (Palazzo Vecchio) and his astute organization laid the foundations for the natural sciences. Astronomical elements surface in designs for the marriage festivities for his heir, Francesco I, whose legendary fascination with the fledgling sciences set the stage for later empiricism.

In the seventeenth century, astronomy emerged as a discipline under Grand Duke Cosimo II, son of Ferdinando I, Francesco’s successor. At the University of Pisa, Cosimo II attended lectures by Galileo Galilei. In 1609, Galileo began his telescopic study of the Moon, followed by observations of the moons of Jupiter. In a clear bid for patronage, Galileo called them the "Stelle Medicee" ("cosmica sidera"). After publication of Siderius Nuncius (1610), containing illustrations from his drawings of the Moon, Galileo was appointed "Philosopher and Mathematician" to the Grand Duke and appointed to the Medici-sponsored Accademia del Disegno. In this court ambiente, his friend Il Cigoli also observed astronomical phenomena. As Francesco I had set up a laboratory in his palace, Cosimo II added an observatory at Poggio Imperiale with a telescope from Galileo, who spent his final years in exile nearby at Arcetri under Medici protection. Today, the Florentine astrophysical observatory stands on this hill, underscoring Medici encouragement of astronomy to advance their prestige, material progress, and power as a modern institution.

The black-drop effect has caused a timing uncertainty of many seconds, providing a major uncertainty to historical methods of using transits of Venus to find the scale of the solar system, notably in the 1761, 1769, 1874, and 1882 transits. We have used NASA’s Transition Region and Coronal Explorer (TRACE) spacecraft to observe the 1999 transit of Mercury. Though Mercury has no appreciable atmosphere and we were observing from outside the Earth’s atmosphere, we nonetheless detected a black-drop effect. Detailed analysis showed that this black-drop effect could be entirely explained by not by only the point-spread function of the telescope but that a contribution from the solar limb-darkening was also necessary. The two contributors together entirely account for the effect, and are undoubtedly also the cause of Venus’s black-drop effect, Venus’s atmosphere being too shallow to account for the historically observed effect. We plan observations from TRACE and from the ground at the June 8, 2004, Venus transit. Details of our Mercury transit observations have appeared in ICARUS.

We report on our observations of the black-drop effect at the 1999 and 2003 transits of Mercury using the high resolution of the Transition Region and Coronal Explorer spacecraft. We have deconvolved the effect for the 1999 event into contributions from the telescope’s point-spread function and the solar limb darkening. The observations are important for understanding historical observations of transits of Venus, which in the 18th and 19th centuries were basic for the determination of the scale of the solar system. Our observations are in preparation for the 8 June 2004 transit of Mercury, the first to occur since 1882.

I report on American textbooks for kindergarten through high-school grades. Middle school, up through approximately age 15, is the last time American students are required to take science, and I provide statistics on the narrowing of the funnel containing those taking physics. I describe some recent curriculum and standards projects, and discuss the recent "less is more" trend. I conclude with comments on whether textbooks are necessary and useful and discuss possible content and style of an ideal textbook. Astronomy is orphaned in many American schools, though it can find its way into classes through earth science or physical science courses or textbooks. We can hope that the students will wind up with better astronomical knowledge than Harry Potter, who "completed the constellation Orion on his chart" in June from his own telescopic observations during his practical astronomy exam in "Harry Potter and the Order of the Phoenix" (Rowling, 2003), an observation that can never be made.

We report on our observations of the black-drop effect at the 1999 and 2003 transits of Mercury using the high resolution of the Transition Region and Coronal Explorer spacecraft. We have deconvolved the effect for the 1999 event into contributions from the telescope’s point-spread function and the solar limb darkening. The observations are important for understanding historical observations of transits of Venus, which in the 18th and 19th centuries were basic for the determination of the scale of the solar system. Our observations are in preparation for the 8 June 2004 transit of Mercury, the first to occur since 1882.

The stellar occultation by Pluto of the 15th magnitude star designated P131.1 (McDonald and Elliot, AJ, 119, 1999) on 2002 August 21 (UT) provided the first significant chance to compare Pluto’s atmospheric structure to that determined from the 1988 occultation of P8 (Millis, et al., Icarus, 105, 282). The P131.1 occultation was observed from several stations in Hawaii and the western United States (Elliot et al., Nature, in press, 2003). Numerous occultation chords were obtained enabling us to examine Pluto’s atmospheric figure. The light curves from the observations were analyzed together in the occultation coordinate system of Elliot et al., (AJ, 106, 2544). The Mauna Kea and Lick datasets straddle the center of Pluto’s figure, providing strong constraints on model fits to cross sections of the atmospheric shape.

In 1988, Millis, et al. (Icarus, 105, 282) did not report any deviation from sphericity in Pluto’s atmospheric figure. From the 2002 data, Pluto’s isobars at the radii probed by the occultation (~1250 km) appear to be distorted from a circular cross-section. Least-squares fits to this cross-section by elliptical models reveal ellipticities in the range 0.05-0.08 although the shape may be more complex than ellipsoidal. The orientation of the distortion appears uncorrelated with Pluto’s rotational axis. Taken at face value, this ellipticity could imply wind speeds of up to twice the sonic speed (~200 m/s), which would be difficult to explain. Similar distortions have been reported for Triton’s atmosphere (Elliot, J. L., et al., Icarus 148, 347). This work has been supported in part by Research Corporation, the Air Force Research Laboratory, NSF, and NASA.

Hormones and Behavior, 44, 402-412 (2003)

Zebra finches are age-limited learners; males crystallize their songs at 90 days and do not subsequently alter those songs. However, a variety of interventions, including deafening and syringeal denervation, result in long-term changes to the crystallized song. These changes can be prevented by lesioning nucleus LMAN. As different social contexts for song production result in differential activation of LMAN, we asked whether the social context experienced by adult males would affect their ability to alter their songs in response to syringeal denervation. Males able to see and direct their songs to females made fewer changes to their songs than did males that could hear but not see females, but this trend was not significant. The volume of a male’s HVc, a forebrain song control nucleus, also failed to predict the degree to which a male would change his song. However, testis mass was significantly correlated with the number of changes made to the song, indicating that variations in testosterone modulate adult song plasticity. We directly tested the effect of circulating testosterone on adult song plasticity by implanting adult males with either testosterone or flutamide, a testosterone receptor blocker, and tracking song changes triggered by ts nerve injury. As predicted, males implanted with testosterone changed their songs less than did males that received flutamide implants. These results suggest that the high testosterone concentrations associated with sexual maturity and song crystallization in zebra finches continue to act in adult males to reduce the potential for vocal plasticity.

Biol. Bull 205, 211-22 (2003)

J Esp Biol 206, 3015-3029 (2003)

A concise route to the title compounds was achieved via annulation of 4,4-dimethylcyclohexenone with 3-cyanophthalide, followed by oxidation with dichlorodicyanobenzoquinone. This three-step process afforded the target compound in 80% overall yield, compared to a previous report which required eight steps and proceeded in less than 50% yield. The product has been shown to exhibit potent lytic activity in vitro against Trypanosoma cruzi, the cause of Chagas’ disease in Latin America.

Filamentous soil bacteria of the genus Streptomyces carry out complex developmental cycles that result in sporulation and production of numerous secondary metabolites with pharmaceutically important activities. To further characterize the molecular basis of these developmental events, we screened for mutants of Streptomyces coelicolor that exhibit aberrant morphological differentiation and/or secondary metabolite production. On the basis of this screening analysis and the subsequent complementation analysis of the mutants obtained we assigned developmental roles to a gene involved in methionine biosynthesis (metH) and two previously uncharacterized genes (SCO6938 and SCO2525) and we reidentified two previously described developmental genes (bldA and bldM). In contrast to most previously studied genes involved in development, the genes newly identified in the present study all appear to encode biosynthetic enzymes instead of regulatory proteins. The MetH methionine synthase appears to be required for conversion of aerial hyphae into chains of spores, SCO6938 is a probable acyl coenzyme A dehydrogenase that contributes to the proper timing of aerial mycelium formation and antibiotic production, and SCO2525 is a putative methyltransferase that influences various aspects of colony growth and development.

In this paper, we use algebraically workable ecological models to introduce students to the methodology of nonlinear chemical kinetics. These models, although non-chemical, are simple enough that a novice can readily determine the important properties of the systems that they represent. Most chemical models involve a great deal of intractable algebra, which can easily confuse undergraduates, and distract them from the principles behind the analytical techniques. Thus, we have sacrificed some of the focus on actual chemical mechanisms in order to concentrate on the basics of the concepts and methods that will eventually allow students to understand more complicated cases. Therefore, following this paper, students with a minimum exposure to linear algebra and/or ordinary differential equations should be able to analyze more complex chemical systems using either paper and a pencil or symbolic algebra software.

For a simple modified Lotka model of two competitive species, we study the importance of intraspecies interaction. In its absence, we are able to analyze the system’s invariant manifolds and find the conditions for coexistence. These conditions are too restrictive and in many cases cannot be achieved in ecological systems. The inclusion of intraspecies interaction yields richer dynamics and a larger region in parameter space, which is more suitable for ecological systems. With the inclusion of diffusion, we study the reaction-diffusion system, which yields a plethora of spatial and spatio-temporal patterns. The key issue is the coexistence between species competing for the same “food.”

Methylcoenzyme M reductase, which contains a square planar nickel corphin cofactor, F430, catalyzes the final step in methane biosynthesis in methanogenic Archaea. Using chemical reactivity and electrochemical studies as well as spin density (UB3LYP) calculations several known tetraazamacrocyclic nickel complexes were evaluated for their suitability as chemical mimics for F430. Cyclic voltammetry and spin density calculations were performed on four complexes, Ni(II)-5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-4,6,11,12-tetraene (Ni(II)-MeHMe[14]), Nickel(II)-6-13-diphenyl-1,5,8,12-tetraazahexadeca-4,6,12,14-tetraene (Ni(II)-HPhH[15]), Nickel(II)-7,15-diphenyl-1,5,9,13-tetraazahexadeca- 5,7,13,15-tetraene (Ni(II)-HPhH[16]), and Nickel(II)-7,15-diphenyl-1,5,9,13-tetraazahexadeca-5,7,13,15-tetraenato
hexafluorophosphate (Ni(II)-HPhH[16ox]PF6). Only Ni(II)-HPhH[16ox]PF6 was found to undergo both reversible oxidation (Ni2+/3+) and quasi-reversible reduction (Ni2+/1+) in accord with the postulated intermediates in the mechanism of methanogenesis. Chemical reduction of Ni(II)-HPhH[16ox]PF6 by Zn/Hg in DMF affords Nickel(I)-7,15-diphenyl-1,5,9,13-tetraazahexadeca-5,7,13,15-hexaene (Ni(I)-HPhH[16ox]) in which both spin density calculations and EPR spectroscopy confirm the formation of a Ni(I) (d9) complex.

Three asymmetric pathways to the kavalactones have been developed. The first method is chiral auxiliary-based and utilizes aldol reactions of N-acetyl thiazolidinethiones followed by a malonate displacement/decarboxylation reaction. The second approach uses the asymmetric catalytic Mukaiyama additions of dienolate nucleophile equivalents developed by Carreira and Sato. Finally, tin-substituted intermediates, prepared by either of these routes, can serve as advanced general precursors of kavalactone derivatives via Pd(0)-catalyzed Stille couplings with aryl halides.

The mathematical thinking, as well as the mathematics, in a computer science education prepares students for all stages of system development, from design to the correctness of the final implementation.

In this paper, we discuss some of the remaining problems in the design of static type systems for object-oriented programming languages. We look at typing problems involved in writing a simple interpreter as a good example of a simple problem leading to difficult typing issues. The difficulties encountered seem to arise in situations where a programmer desires to simultaneously refine mutually interdependent classes and object types.

In this talk, we discuss the problem of simultaneously refining mutually interdependent classes and object types. We discuss possible solutions using existing static type systems that include polymorphism. A statically type-safe solution is presented that involves the introduction of type groups, a construct that can be understood as a generalization of the MyType construct introduced in a statically type-safe way in languages like PolyTOIL and LOOM.

The Java Virtual Machine executes bytecode programs that may have been sent from other, possibly untrusted, locations on the network. Since the transmitted code may be written by a malicious party or corrupted during network transmission, the Java Virtual Machine contains a bytecode verifier to check the code for type errors before it is run. As illustrated by reported attacks on Java run-time systems, the verifier is essential for system security. However, no formal specification of the bytecode verifier exists in the Java Virtual Machine Specification published by Sun. In this paper, we develop such a specification in the form of a type system for a subset of the bytecode language. The subset includes classes, interfaces, constructors, methods, exceptions, and bytecode subroutines. We also present a type checking algorithm and prototype bytecode verifier implementation, and we conclude by discussing other applications of this work. For example, we show how to extend our formal system to check other program properties, such as the correct use of object locks.

Ensuring the correctness of multithreaded programs is difficult, due to the potential for unexpected interactions between concurrent threads. Much previous work has focused on detecting race conditions, but the absence of race conditions does not by itself prevent undesired thread interactions. We focus on the more fundamental non-interference property of atomicity; a method is atomic if its execution is not affected by and does not interfere with concurrently-executing threads. Atomic methods can be understood according to their sequential semantics, which significantly simplifies (formal and informal) correctness arguments.

This paper presents a dynamic analysis for detecting atomicity violations. This analysis combines ideas from both Lipton’s theory of reduction and earlier dynamic race detectors. Experience with a prototype checker for multithreaded Java code demonstrates that this approach is effective for detecting errors due to unintended interactions between threads. In particular, our atomicity checker detects errors that would be missed by standard race detectors, and it produces fewer false alarms on benign races that do not cause atomicity violations. Our experimental results also indicate that the majority of methods in our benchmarks are atomic, supporting our hypothesis that atomicity is a standard methodology in multithreaded programming.

Ensuring the reliability of multithreaded software systems is difficult due to the potential for subtle interactions between threads. We present a new modular verification technique to check concise specifications of large multithreaded programs. Our analysis scales to systems with large numbers of procedures and threads. We achieve thread-modular analysis by annotating each shared variable by an access predicate that summarizes the condition under which a thread may access that variable. We achieve procedure-modular analysis by annotating each procedure with a specification related to its implementation by an abstraction relation combining the notions of simulation and reduction. We have implemented our analysis in Calvin-R, a static checker for multithreaded Java programs.

A P4 is an induced path with four vertices. A bichromatic P4 composition scheme is as follows: (1) start with two graphs with vertex sets of different color, say black • and white o, (2) select a set of allowable four-vertex bichromatic sequences, for example {••••,oooo,•oo•,o••o}, (3) add edges between the graphs so that in the composed graph each P4 is colored with an allowable sequence. Answering a question of Chvátal, we determine all such schemes which preserve perfect orderability.

Over the last two decades, efficient message passing libraries have been developed for parallel scientific computation. Concurrently, programming languages have been created supporting dynamically reconfigurable distributed systems over the heterogeneous Internet. In this paper, we introduce SALSA-MPI, an actor programming language approach to scientific computing that extends MPI with a checkpointing and migration API and a runtime system that manages both periodic checkpoints and process or application migration. The goal is to enable dynamic network reconfiguration and load balancing without sacrificing application performance or requiring extensive code modifications. As driving technology for this effort of unifying parallel and distributed computing, we plan to use adaptive solvers of partial differential equations. Fields as diverse as fluid dynamics, material science, biomechanics, and ecology make use of parallel adaptive computation, but target architectures have traditionally been supercomputers and tightly coupled clusters. SALSA-MPI is intended to allow these computations to make efficient use of more distributed and dynamic computing resources.

Detrital zircon U-Pb ages determined by SHRIMP distinguish two clastic sequences among Proterozoic metasedimentary rocks from central Madagascar. The Itremo Group is the older: zircon data, stromatolite characteristics and carbon isotope data all point to a depositional age around 1500-1700 Ma. The Molo Group is younger, deposited between ~620 Ma (the age of the youngest zircon) and ~560 Ma (the age of metamorphic overgrowths on detrital cores). Geochronologic provenance analysis of the Itremo Group points to sources in East Africa as well as local sources in central and southern Madagascar, but provides no evidence for a detrital contribution from northern and eastern Madagascar nor from southern India. Detrital zircon and sedimentologic similarities between rocks of the Itremo Group and the Zambian Muva Supergroup suggest a lithostratigraphic correlation between the two. The Molo Group has a strong 1000-1100 Ma detrital signature that also indicates an east African provenance, and suggests a Neoproterozoic geographic connection with Sri Lanka, but shows no indication of input from the Dharwar craton/eastern Madagascar. Central Madagascar was probably juxtaposed with the Tanzanian craton in the Paleo- and Mesoproterozoic, whereas northern and eastern Madagascar were connected to India. Internal assembly of Madagascar postdates Neoproterozoic Molo Group sedimentation and is likely to have occurred at about 560 Ma.

The Itremo Group of central Madagascar was deposited sometime between 1500-1700 Ma based on evidence from U-Pb ages of detrital zircons from quartzites, carbon isotope signatures of marbles, and stromatolite morphology. It contains several Paleoproterozoic and late Archean detrital zircon populations with two dominant ones at 1850 ± 3 Ma (30% of 130 detrital ages analyzed by mixture modeling) and 2500 ± 2 Ma (35% of grains analyzed). Preliminary data from the Sahantaha Series in northern Madagascar indicate strong correspondence with the Itremo Group, with detrital ages concentrated at 1834 ± 4 Ma and 2502 ± 8 Ma. Basement rocks around 2500 Ma are known from within Madagascar, but 1850 Ma rocks are not, so a non-Malagasy source terrane is required. Comparison of detrital ages with U-Pb basement ages in neighboring continents indicates a predominantly East African provenance, as there is increasing documentation of 1850 Ma ages in the Tanzanian craton and surrounding area but rocks of this age are absent from the Dharwar Craton of India. Of equal importance, the mid-Archean ages that are common in the Dharwar craton and the Antongil block of northeastern Madagascar are not found in the Malagasy metasediments. We conclude that India and the Antongil block were distant from the continental shelf environments where the Itremo Group and Sahantaha Series were deposited. Paleogeographic reconstructions in which Madagascar is located next to India, along the western edge of Rodinia, are therefore probably incorrect. It is likely that the small Antongil block in northeastern Madagascar was part of India, but our data suggest that most of Madagascar was in fact juxtaposed with the Tanzanian craton in the Paleo- and Mesoproterozoic, possibly forming a passive margin along the western side of the Mozambique ocean. This also means that the components of modern Madagascar were not assembled until Neoproterozoic time.

Lavaka (the Malagasy word means "hole") are characteristic, extremely conspicuous features in the recently uplifted highlands in central Madagascar. They occur in deeply-lateritised and saprolitic Precambrian basement rocks, in steep hilly country, on convex slopes that are generally bare of outcrop. Lavaka formation is poorly understood, and has multiple causes; but field measurements from areas north and west of Antananarivo indicate that lavaka occurrence and geometry are controlled by a combination of slope steepness and the attitude of gneissic foliation in the bedrock. The saprolite preserves the gneissic foliation, so that strike and dip measurements were possible in the lavaka interiors.

There is a complete continuum in lavaka geometry, but they can be subdivided into simple and complex. Simple lavaka are most common. They are bulbous in shape and strongly symmetric, with a broad head scarp, wide interior basin (with or without internal septa) and well-defined, narrow outflow channel. Complex lavaka include composite or dentritic varieties consisting of multiple coalesced simple lavaka, and asymmetric groups of gullies and ravines, usually with a broader, more valley-like outflow.

Simple lavaka form readily in strongly convex slopes where the bedrock (saprolite) foliation dips into the hillside. The gradient in the head scarp region is usually 5-20°, becoming steeper (20-40°) downslope, where the narrow outflow channel is deeply incised; and the fall line of the lavaka is generally normal to the bedrock strike and opposite to the dip direction. To illustrate: if gneissic bedrock strikes north-south and dips west, east-facing hillsides will develop east-west oriented, east-draining simple lavaka, but west-facing (dip-slope) hillsides will not.

Complex lavaka are associated with steeply dipping (85-90°) gneissic foliation, and also tend to occur on slopes that are more gentle (15-25°) or less dramatically concave. Under these conditions, linear or irregular gullies may occur parallel to the foliation, or at an angle to it. Lobes with simple lavaka geometry may form as part of the complex where the local dip of foliation is into the hillside.

The weathered zone records the balance between rock resistance, weathering and erosion near the late Pleistocene glacial limit in the Front Range, Colorado. We used drillers’ logs from ~1000 wells and field measurements to map patterns of regolith thickness in six adjoining 7.5’ quadrangles in the Boulder Creek catchment. Alluvial and glaciofluvial deposits generally are thin (< 3 m) except along Boulder Creek upstream from the glacial limit, where gravel in limited areas is as thick as 15 m. Most regolith formed from weathering of fractured and faulted Precambrian granitic gneiss and metasedimentary rocks that are locally rich in biotite. Saprolite thickness is not a simple function of bedrock type, faulting, or modern topography. Areas glaciated by Pinedale and Bull Lake valley glaciers expose fresh rock and zones of fractured, slightly weathered rock as thick as 5 m. Ridges separating glaciated valleys expose a relatively thick weathered mantle at elevations as high as about 2800 m. East of the glacial limit, the mean depth to bedrock is between 5 and 10 m and exceeds 10 m in extensive areas. The sharp boundary between glacially stripped bedrock and thick weathered zones implies that the zone of periglacial processes did not extend more than a few km beyond ice margins. Where the weathered zone is exposed in roadcuts, the upper 1 to 4 m consists of grus, saprolite or weathered saprolite with density values between 1.2 and 1.7 g cm-3. Geomorphic evidence suggests that the weathered mantle could not have formed under present conditions. Soils developed on Bull Lake-age moraines expose Bt horizons on the most stable sites, but in many areas soils are oxidized to depths <150 cm and contain > 50 percent fresh to slightly weathered clasts. These observations indicate that in climate typical of late Pleistocene time, the weathered bedrock zone would have taken >> 100 kyr to form. Concentrations of cosmogenic nuclides (CRNs) in quartz extracted from stream sediment from several local catchments suggest that erosion rates over the past 30 kyr have averaged about 2.5 cm/kyr. Erosion rates derived from CRNs thus are 2 to 3 X soil formation rates and by inference, regolith formation rates. Deeply weathered bedrock may reflect a pre-Pleistocene landscape mainly removed by glacial activity and thinning rapidly in areas beyond the glacial limit.

Near Loreto in Baja California Sur, Mexico, the Cerro Mencenares volcanic complex is cut by north-south trending faults compatible with an extensional tectonic history. In contrast, El Coloradito Fault strikes onshore from the Gulf of California toward Cerro Mencenares on an azimuth of N55ºW oblique to the dominant north-south structural pattern on land. A 30-m high scarp traces part of this fault and defines the south side of the uplifted “El Mangle” block formed by a headland of Miocene volcanic rocks in the Comondú Group. El Coloradito fault is oriented parallel to active transform faults in the Gulf of California.

Development of the coast on the east flank of the Cerro Mencenares complex is recorded by a sequence of terrestrial and marine facies combined in a single ramp feature exposed near the mouth of Arroyo El Mangle. With a uniform seaward inclination of 6º, the ramp succession sits unconformably on a 310-m-wide andesitic shelf. Several distinctive units extend 8 km across Ensenada El Mangle along the shoreface of the Gulf of California. The sequence represents a transgressive-regressive package that includes red clays and tuffs, silicified debris from salt-tolerant land plants, conglomerate beds with an intertidal marine biota, and limestone dominated by pectens and echinoids. The ramp correlates with the Middle Pliocene Piacenzian Stage based on tuffs near the base of the succession that yield a K/Ar age of 3.3 Ma. Fossils from the limestone, including the echinoid Clypeaster marquerensis and sand dollar Encope shepherdi confirm a middle to upper Pliocene position. The same limestone crops out on the opposite side of El Coloradito Fault from the main ramp, which is buttressed against a sequence of columnar basalts and volcanic breccia. In this case, however, the ramp has a seaward dip of 12º. The elevation difference between adjacent limestone beds indicates a minimum uplift of 70 m for the upthrown block on the north side of El Coloradito fault. The exaggerated dip of the limestone also indicates tectonic over-steepening compared to the undisturbed ramp on the south side of El Coloradito fault. The abrupt westward termination of El Coloradito fault on north-south-trending normal faults that define El Mangle block suggest the geometry of a fracture zone reactivated by compression against the flanks of the Cerro Mencenares volcanic complex sometime after 3.3 Ma. Carbonate ramps are well documented elsewhere in the Pliocene of Baja California, but at El mangle a major ramp that postdates orthogonal extension was disrupted by a transtensional oblique fault.

The Lower Cretaceous (Aptian-Albian) Alisitos Formation is well exposed at Punta San Isidro and adjacent sea cliffs on the Pacific shores of Baja California near Eréndira, Mexico. Continuous coastal outcrops define a local stratigraphic succession less than 100 m in total thickness, including repetitious tuff, sandstone and conglomerate units interbedded with discontinuous limestone beds rarely more than 2.5 m thick. The limestone beds are biostromal units that include scattered oysters and/or corals, as well as units dominated by the rudistid bivalve, Caprinuloidea perfecta. Two distinctive conglomerate units are composed of andesite cobbles colonized by encrusting oysters in a quasi rocky-shore setting. One sandstone unit includes abundant fossil wood with tree limbs up to 55 cm long and 5 cm in diameter. Proximal volcanic activity is indicated by a series of dikes that cut through pyroclastic beds and lead to a 10-m thick andesitic flow that caps the succession at Punta San Isidro. Compared with thicker intervals of the Alisitos Formation elsewhere in Baja California that are dominated by andesitic flows and offshore limestone, the Punta San Isidro sequence offers a window on a back-reef environment adjacent to a paleoshore that received pyroclastic lahars from a terrestrial origin or mass flows from shallow submarine explosions. Recovery of marine life and the renewal of a carbonate substrate followed successive episodes of volcanism and massive erosion along an active coastline. This scenario is very different from depositional processes of the Upper Cretaceous (Campanian-Maastrichtian) Rosario Formation that cannibalized and subsequently formed a regional unconformity against tilted Alisitos strata with substantial topographic relief in the Eréndira region.

The Ordovician Taconic orogeny in western New England was typically ascribed to a collision between the Laurentian margin and a magmatic arc identified as the Bronson Hill arc. However, in central Massachusetts and southern New Hampshire, rocks in the Bronson Hill arc are 454 to 442 Ma (Tucker and Robinson, 1990) and, therefore, younger than the onset of Taconic metamorphism in western New England and Quebec, which began by approximately 470 to 460 Ma (Laird and others, 1984; Castonguay and others, 1997). Karabinos and others (1998) used U-Pb zircon ages and geochemistry to document the presence of an older magmatic arc, the Shelburne Falls arc, that formed west of the Bronson Hill arc by approximately 485 to 470 Ma above an east-dipping subduction zone. The Taconic orogeny was the result of the collision between Laurentia and the Shelburne Falls arc beginning at approximately 470 Ma. The younger Bronson Hill arc formed above a west-dipping subduction zone that developed along the eastern edge of the newly accreted terrane after the Taconic orogeny. The Taconic orogeny ended when plate convergence between Laurentia and Iapetus was accommodated by the newly developed west-dipping subduction zone instead of by crustal shortening in the Taconian thrust belt.

Discontinuous sills of alaskite in the interior and western margin of the Berkshire massif and granite on the eastern margin of the massif were mapped by Ratcliffe (1984a, 1984b, 1985) and Ratcliffe and Hatch (1979), and interpreted by them as syntectonic anatectic melts that intruded Taconic thrusts. The alaskite sills are most commonly found in the Middle Proterozoic Tyringham Gneiss and many of the mapped Taconic thrusts within the massif closely follow the distribution of the alaskite bodies. The granite sills are found in both Middle Proterozoic basement and the Late Proterozoic Hoosac Formation.

We collected one sample of the Tyringham Gneiss and thirteen samples of alaskite, ranging in composition from granite to trondhjemite, for geochemical analysis and SHRIMP analysis to date the age of thrusting in the Berkshire massif. Geochemically, the alaskite sills are diverse, suggesting that some combination of partial melting of different source rocks, different degrees of partial melting, fractionation, and contamination during transport was involved in their genesis. Zircons from the Tyringham Gneiss contain cores with oscillatory zoning and thin homogeneous rims. The weighted average of eight 206Pb/238U analyses from the cores is 1179 ± 9 Ma, whereas nine 206Pb/238U spot analyses from the rims yield an age of 1004 ± 9 Ma; we interpret these to represent the crystallization age of the Tyringham Gneiss protolith and subsequent high grade metamorphism, respectively. Zircons from three samples of alaskite commonly contain xenocrystic cores that yield a wide range of ages from approximately 1050 to 1230 Ma surrounded by broad rims which commonly display oscillatory zoning. Many grains also show oscillatory zoning with no cores. The weighted average of sixteen 206Pb/238U analyses from grains without cores and rims of grains with cores in one alaskite sample is 997 ± 10 Ma, the weighted average of eight analyses from the second sample is 1004 ± 19 Ma and seven spot analyses from a third sample give a weighted average of 1003 ± 8 Ma. We suggest that the alaskite bodies formed during either the Ottawan or Rigolet phase of the Grenville orogeny and that they have no connection to the Taconic orogeny.

We also collected five samples of granitic sills from the eastern margin of the Berkshire massif that intruded both Middle Proterozoic basement and the Late Proterozoic Hoosac Formation near their contact. These sills were also interpreted as syntectonic intrusives along Taconic faults (Ratcliffe and Hatch, 1979). Geochemically, the sills, which we informally refer to as the granite of Becket Quarry, are very consistent, suggesting that they formed by partial melting of a single source rock. The concordia plot for one sample shows a strong cluster of young ages that give a weighted average 206Pb/238U age of 432 ± 3 Ma (n=11). The older core 207Pb/206Pb ages range from ca. 960 to 1250 Ma. The concordia plot for another sample also has a strong cluster of young ages that give a weighted average 206Pb/238U age of 434 ± 5 Ma (n=8). The older core 207Pb/206Pb ages for this sample range widely from ca. 790 to 1170 Ma. We interpret the 432 ± 3 Ma and 434 ± 5 Ma ages as the time of crystallization of the granite of Becket Quarry. The older cores are xenocrystic and their ages indicate that Middle Proterozoic basement rocks were partially melted to produce the granite during the Silurian.

The western, basal contact between Middle Proterozoic rocks of the Berkshire massif and underlying Early Paleozoic rocks is clearly a thrust, but there is no independent evidence that movement occurred during the Taconic orogeny, and it may be an Acadian fault. Many contacts within the Berkshire massif mapped as Taconic thrusts that follow the distribution of the alaskite sills must either be Middle Proterozoic faults or, more likely, intrusive contacts between older basement gneisses and younger anatectic melts. Instead of being deformed into an imbricate stack, the massif may have behaved as a rigid block during Paleozoic uplift. Finally, the eastern margin of the massif may be a Silurian fault, possibly related to extension and the opening of the Connecticut Valley trough, rather than a Taconic thrust.

Although it is now possible to date single grains of monazite with the ion and electron microprobes, and to resolve multiple age domains within single grains, it is commonly difficult to demonstrate that individually dated grains or domains grew during the development of specific deformation fabrics. Because careful field observations can link fabrics with map-scale folds and faults, it is vital to develop sound microstructural criteria to date monazite growth relative to fabrics in order to establish a meaningful structural chronology. The approach we used to establish the timing of monazite growth relative to fabric development was to compare monazite characteristics in similar lithologies across a zone with a large strain gradient in the Chester dome, Vermont.

It is widely accepted that rocks in southeastern Vermont were affected by both the Ordovician Taconic and Devonian Acadian orogenies. Monazite is a common accessory phase in pelitic schist and grains are typically irregularly shaped and approximately equant. Monazite grains from three samples of Late Proterozoic to Cambrian schist near the Chester dome, but outside of a high strain zone (HSZ), are chemically zoned and contain two or more distinct age domains. Electron microprobe (EMP) ages show multi-modal distributions consistent with metamorphic growth during the Taconic, Acadian, and Pennsylvanian Alleghenian orogenies. In sharp contrast, monazite grains in samples within the HSZ that rims the Chester dome are elongated parallel to the mylonitic fabric and are chemically homogeneous. EMP ages from two HSZ samples from Townshend Dam both show a normal distribution that give averages of 380 ± 31 Ma (standard deviation) and ± 3 Ma (standard error) (n = 124) and 384 ± 36 Ma (s.d.) and ± 5 Ma (s.e.) (n = 64). Monazite that predated mylonitization of these rocks was thoroughly recrystallized during intense deformation in the HSZ. Lithologic units are dramatically thinned or entirely absent in the HSZ, compared with similar units elsewhere in southeastern Vermont, and we interpret the HSZ as a normal ductile shear zone that formed during Acadian extension at approximately 380 Ma.

Discontinuous sills of granite along the eastern margin of the Berkshire massif were interpreted by Ratcliffe and Hatch (1979) as syntectonic anatectic melts that intruded a Taconic thrust zone separating Middle Proterozoic basement from the structurally overlying Late Proterozoic Hoosac Formation. The granite sills vary in thickness from 1 to 100 m and are found in both the basement rocks and the Hoosac Formation. Exposed sill contacts are sharp and the granite is weakly to moderately foliated. Five samples from the Becket and Otis 7.5” quadrangles are geochemically homogeneous. They plot in the volcanic arc granite field on commonly used tectonic discrimination diagrams. The concordia plot of SHRIMP ages for one sample shows a strong cluster of young rims that give a weighted average 206Pb/238U age of 432 ± 3 Ma (n=11). The older core 207Pb/206Pb ages from this sample range from ca. 960 to 1250 Ma. The concordia plot for another sample also has a strong cluster of young ages that give a weighted average 206Pb/238U age of 434 ± 5 Ma (n=8). The older core 207Pb/206Pb ages for this sample range widely from ca. 790 to 1170 Ma. We interpret the 432 ± 3 Ma and 434 ± 5 Ma ages as the time of crystallization of the granite of Becket Quarry. The older cores are xenocrystic and their ages indicate that the granite sills were produced by, or at least contaminated by, partial melting of Middle Proterozoic basement rocks. The arc geochemical affinity of the sills may be inherited from partial melting of Middle Proterozoic arc-related rocks. Alternatively, the sills may record a limited magmatic pulse above a west-dipping Silurian subduction zone under the Laurentian margin during an interval dominated by back-arc basin extension. The age of the sills, together with their proximity to a fault zone that juxtaposes younger on top of older rocks, suggests that the eastern margin of the Berkshire massif is a Silurian normal fault, possibly related to extension and the opening of the Connecticut Valley trough.

Large-scale zones of weakness parallel to continental margins include low-angle normal faults formed during rifting and suture zones formed during accretion of continental ribbons and island arcs. These and other crustal-scale discontinuities commonly separate blocks with markedly different mechanical properties and may facilitate strain partitioning into orogen-normal and orogen-parallel components during later continent-continent collision. Diverse evidence suggests that large-scale fault zones and heterogeneous rheology resulted in orogen-parallel transport of accreted arcs and gneiss dome formation in the northern Appalachians.

There are two north-south trending sets of gneiss domes in the New England Appalachians. The western belt contains thirteen domes that expose either 1 Ga Laurentian basement rocks or 475 Ma rocks of the Shelburne Falls arc. The eastern belt contains twenty-one gneiss domes cored by either 600 Ma Avalonian (?) crust or 450 Ma rocks of the Bronson Hill arc. Both sets of domes are flanked by Silurian to Early Devonian metasedimentary rocks that were deposited in two north-south trending basins just before the Late Silurian to Early Devonian Acadian orogeny. The Connecticut Valley trough formed in the region between the Shelburne Falls and Bronson Hill arcs, probably as a Silurian back-arc basin above a west-dipping subduction zone after Bronson Hill arc magmatism ceased (Karabinos et al., 1998). The Central Maine terrane formed east of the Bronson Hill arc in a vanishing ocean basin prior to the collision between Laurentia and composite Avalon. During an early stage of Acadian deformation, metasediments from both the Connecticut Valley trough and Central Maine terrane were transported westward as large-scale nappes over the regions now occupied by the western and eastern belts of gneiss domes, respectively. The gneiss domes are commonly elongated north-south and surrounded by thin zones of intensely deformed rocks between the core gneisses and the mantling metasediments. The nappes were refolded during doming. The nappe and dome stages of deformation explain much of the structural geometry of the region (e.g., Thompson et al., 1968; Rosenfeld, 1968), but an unresolved problem is a mechanism for the dramatic thinning and omission of units in the high-strain zones around the domes.

Most of my detailed observations come from the Chester dome in the western dome belt, but similar features are present in other domes. Within the high-strain zone above the core gneisses of the Chester dome, lithologic units are extremely attenuated or missing entirely when compared with the structural section elsewhere in southern Vermont. Karabinos (2002) argued that the high-strain zone formed as a ductile normal-sense shear zone during the Acadian orogeny, in contrast to the previous interpretation of numerous Taconic thrust faults (e.g. Ratcliffe et al., 1997). The sense of shear from indicators in outcrop, slabbed hand samples, and thin sections, including asymmetric extensional shear bands, c-s fabrics, and rotated porphyroclasts, indicate that rocks above the high-strain zone were displaced southwest relative to rocks below it. These observations are consistent with elongated pebbles and phenocrysts that Rosenfeld (1968) used to document strong northeast to southwest Acadian extensional strain. Pressure-temperature paths of rocks from below the high-strain zone indicate decompression of several kilobars during metamorphism, whereas rocks above the high-strain zone record nearly isobaric conditions. This pattern is consistent with normal-sense displacement between the core of the dome and its mantling sequence during Acadian metamorphism.

Two remarkable features of the gneiss dome belts in New England suggest that northward extrusion of lower to middle crustal wedges occurred. The first is the location of the domes in a region where the Acadian orogen is very narrow but widens dramatically to the north; the belt from the eastern edge of the Lower Paleozoic shelf sequence to the east side of the Bronson Hill arc is only 75 km in southern New England but more than 175 km in northern New England. The second is the mechanical decoupling between the quartz-feldspar-rich core gneisses of the domes and the overlying nappes of mica-rich metasediments that must have occurred during deformation. The kilometer-scale recumbent folds and thin thrust sheets of Silurian and Devonian metasediments which were squeezed westward out of the Connecticut Valley trough and Central Maine terrane did not involve basement gneisses and arc-related rocks of the dome cores. The high-strain zone around the Chester dome, and other domes in the western belt, appear to mark the mechanical boundary between the core rocks and the mantling sequence. A similar relationship between the core rocks and mantling sequence holds true in the eastern dome belt (e.g. Thompson et al., 1968).

Pressure estimates of approximately 10 kbar indicate significant tectonic burial of rocks in the core of the Chester dome, presumably during the westward transport of nappes from the Connecticut Valley trough. East-west shortening of the more rigid lower to middle crustal rocks below the nappes would have required enormous work against this gravitational load. It was energetically more favorable for the wedges of quartz-feldspar-rich gneiss to be transported northward where the orogen was wider and not as dramatically thickened. During this transport, or extrusion, the quartz-feldspar-rich gneisses cut upsection toward the nappes of Silurian rocks and the thickness of the Lower Paleozoic section was dramatically reduced. Numerous zones of weakness parallel to the orogen would have facilitated differential movement of deep crustal wedges; potential weak zones include Late Proterozoic normal faults (rifting of Rodinia), the Taconic suture zone (collision of Shelburne Falls arc), Silurian normal faults (opening of Connecticut Valley trough), and the Acadian suture zone (collision of composite Avalon). The important point here is that north-south extensional flow and attenuation of the mantling sequence could have been coeval with east-west shortening that folded the domes. The New England gneiss domes may owe their north-south elongation and streamlined shapes to this flow pattern. It is also important to note that the upward movement of the core gneisses into the overlying metasediments shares some kinematic characteristics with the classic diapiric model for mantled gneiss domes.

Coccolithophorids are the only marine organisms that provide indicators of past climatic and oceanographic conditions from both the organic (molecular fossils or biomarkers) and inorganic (calcium carbonate) remains in sediments. The undersaturation ratio of alkenone biomarkers (U37K) provides information about past sea surface temperatures and is gaining widespread use as a paleotemperature proxy, particularly in the Quaternary sediment record. The carbon isotopic fractionation in alkenone biomarkers (alkenone) should allow reconstruction of past dissolved and atmospheric CO2 concentrations if independent proxies are able to consistently constrain the nutrient or growth rate influence on isotopic fractionation. The Sr/Ca ratio of coccolith carbonate is the most developed proxy from the elemental chemistry of coccoliths. Recent culture and field studies suggest that the Sr/Ca ratio has potential as an indicator of nutrient-stimulated coccolithophorid growth rates. In contrast, while the Mg/Ca ratio of coccoliths is probably controlled by temperature, formidable challenges in removing noncarbonate sources of Mg from coccolith fractions will probably preclude use of coccolith Mg/Ca for paleothermometry. Similar challenges in cleaning will probably also preclude use of coccolith Cd, Ba, V, or U. Stable isotopic measurements in coccolith-dominated bulk carbonate have been widely used to infer temperature changes and changes in the carbon cycle in the Mesozoic and Early Cenozoic, despite an array of nonequilibrium or “vital effects” in different species. In addition to paleoceanographic applications, continued study of the stable isotopic fractionation of coccoliths in culture may also elucidate mechanisms of carbon acquisition in different coccolithophorid species. As is the case for all paleoceanographic proxies, continued calibration studies are required to further improve our understanding of coccolithophorid-based proxy systems and increase confidence in their paleoapplication

Coccoliths are the dominant form of carbonate in many Neogene and Paleogene marine sediments. Recent culture and sediment core top studies suggest that coccolith Sr/Ca ratios increase with nutrient-stimulated growth rates, potentially offering a new indicator of the productivity of the coccolithophorid algae. Unlike many other common productivity indicators, the coccolith Sr/Ca indicator does not depend on knowledge of the sediment accumulation rate that can be difficult to determine with precision in pre-Quaternary sediments. Separation of near-monospecific coccolith fractions from sediments can yield species-specific Sr/Ca records. This method was applied to sediments from the Weddell Sea (ODP site 690) to test whether marine productivity increased during the Paleocene-Eocene Thermal Maximum. In the dominant coccolithophorid genus Toweius, a large (40%) Sr/Ca increase immediately after the carbon isotope excursion suggests an important increase in nutrient availability and coccolithophorid productivity. Productivity levels remain high for 60,000 years but decrease to pre-event levels within 120,000 years. Productivity levels during the PETM are higher than observed at any other time in the 400,000 year record. Elevated productivity corresponds with locally and globally increased silicate weathering intensity indicated by clay mineral assemblages and Os isotope records; increased weathering intensity may have accelerated nutrient fluxes to near-continent regions. If this type of productivity response occurred globally, it would also be consistent with the timing of C drawdown that may have returned temperatures to near pre-event levels. Unfortunately, at other PETM sites like Blake-Bahama Plateau (ODP 1051) and Shatsky Rise (ODP 1209), application of the coccolith Sr/Ca technique is limited by abundant non-coccolith carbonate in the coccolith size fraction. Analysis of stable isotopes in near-monospecific coccolith fractions from Paleocene sediments illustrates a small range of vital effects among different species and reaffirms the fidelity of coccolith-dominated bulk carbonate records for this event.

Marine algae coccolithophorids produce elaborate micron-scale calcite plates or coccoliths, entirely within their cell. The elemental chemistry of these coccoliths provides clues about the processes of biomineralization and rate of transport of ions to the sites of calcification, and may serve as a paleoceanographic proxy for the productivity of this key algal group. Previous study of coccolith chemistry was limited by the small number of species currently isolated in culture and challenges separating particular genera or species of coccoliths from diverse sediment populations. We describe a new technique for analysis of the Sr/Ca and Mg/Ca ratios of individually picked coccoliths using SIMS with the Cameca IMS 3f ion probe. Compared to other marine biogenic calcites, coccoliths exhibit very large interspecific differences in chemistry. Paleocene coccoliths analyzed with SIMS show a nearly six fold range of Sr/Ca ratios among different genera from a given sample depth, with lowest ratios among Discoaster multiradiatus and highest ratios in the genus Fasciculithus. We will also describe the application of this ion probe method to coccoliths from modern plankton samples. We will assess the range of elemental chemistries in modern species and its relationship to different modes of crystallographic assembly in different coccolith species, and evaluate evidence for variable cellular Sr uptake and incorporation in calcite in response to nutrient-stimulated growth rates.

The Godsend mining claim, staked by Richard Fretterd in 2001, is in the Crystal Creek area, west of Crystal Peak, in Teller County, Colorado. North of U.S. Highway 24 between the towns of Florissant and Lake George, this famous collecting site spans the Teller-Park county lines. Since the 1870’s, some of the world’s finest examples of amazonite, smoky quartz, and other minerals have been mined from the Lake George pegmatite district, which includes Crystal Peak and the Crystal Creek area.

The 29 km2Lake George intrusive center, which surrounds the Lake George pegmatite district, is actually composite, containing rocks of both the potassic and sodic series in a circular or concentric pattern. Rocks of the sodic series (fayalite granite and quartz syenite) form partial ring dikes around a central stock of dark-green syenite. These sodic rocks were intruded into a late stock of fine-grained granite to fine- to medium-grained porphyritic granite of the potassic series. Most of the productive pegmatite prospects of the Lake George district are in this latter rock unit. The Godsend lies on the edge of the Lake George intrusive center.

The Godsend pegmatites exhibit a gradational pattern with aplite as an outer band abruptly changing to a zone of graphic granite where crystal cavities may occur. The aplite granite has a sugary texture and resembles sandstone. The intergrowth of feldspar and quartz characterize the graphic granite.

Ultramafic rocks are rare in the Early Proterozoic basement of Colorado, and we report the only known occurrence in the southern Front Range. At Badger Flats south of Tarryall, a thin sill-like body of peridotite is exposed for 3 km along strike within a thick sequence of sillimanite-grade metapelites and minor interlayered amphibolites (mostly metabasalts). All the layered rocks and the sill are cut by the oldest calc-alkaline plutons of the region (ca. 1.7 Ga), and all experienced regional metamorphism just prior to that. The peridotite contains primary olivine, orthopyroxene, and spinel, overprinted by two metamorphic amphiboles (anthophyllite and magnesio-hornblende, the latter forming oikocrysts >1 cm across). It is low in silica (41-44%), high in MgO (19-25%; Mg# averages 65), and enriched in Cr (800-1600 ppm) and Ni (400-1100 ppm). Compatible and incompatible trace elements average 3-5x primordial mantle values, with greatest enrichment in U and minor depletion in Nb and Sr. REE values are nearly flat at about 10x chondrite, with Gd/Yb(N) approx. 1.0 and La/Sm(N)=1.0-1.5. Geochemically the peridotite resembles a group of metavolcanic rocks of similar age termed komatiites and komatiitic basalts, which Boardman (2000) studied near Mt. Ouray 80 km to the southwest. Spatially associated metabasalts are tholeiitic with primitive island-arc affinities typical of metabasalts throughout the southern Front Range (Folley, 1997). There is no physical or chemical evidence that the peridotite is a cumulate from the fractionation of these basalts, nor are there any possible felsic differentiates of the basalts nearby. The peridotite is thus interpreted to have formed from an ultramafic magma representing a higher degree of partial melting of a hotter Early Proterozoic mantle, perhaps within a back-arc extensional setting.

This paper presents qualitative, sociological, and historical arguments in favor of collaborative research having greater epistemic authority than research performed by individual scientists alone. Quantitatively, epistemic authority is predicted to correlate with citations both in number, probability of citation, and length of citation history. Data from a preliminary longitudinal study of 33 researchers supports the predicted effects, and, despite the fallacy of asserting the consequent, is taken to confirm the hypothesis that collaborative research does in fact have greater epistemic authority.

First book in series of expository comic style books about mathematics with attached toys.

A construction is presented which can be utilized to prove incompressibility of boundary in a 3-manifold. This can be utilized to show that a candidate arc c is not an unknotting tunnel for a cusped 3-manifold. It can also be used to show that a “tubed surface” is incompressible.

This paper is an investigation of geodesics in cusped hyperbolic 3-manifolds. We derive conditions guaranteeing the existence of geodesics avoiding the cusps and use these geodesics to show that in “almost all” finite volume hyperbolic 3-manifolds, infinitely many horoballs in the universal cover corresponding to a cusp are visible in a fundamental domain of the cusp when viewed from infinity.

What happens when the three little pigs decide to get Ph.D.’s in mathematics.

A new faculty member tries to deal with an unusual chair.

What happens when a father claims his daughter can turn coffee into theorems.

When Hollywood discovers mathematics, this is the result.

A function from a triangle to itself is defined that has both interesting number theoretic and analytic properties. This function is shown to be a natural generalization of the classical Minkowski ?(x) function. It is shown there exists a natural class of pairs of cubic irrational numbers in the same cubic number field that are mapped to pairs of rational numbers, in analog to ?(x) mapping quadratic irrationals on the unit interval to rational numbers on the unit interval. It is also shown that this new function satisfies an analog to the fact that ?(x), while increasing and continuous, has derivative zero almost everywhere.

In 1988 Rieger exhibited a differentiable function having a zero at the golden ratio (–1+√5)/2 for which when Newton’s method for approximating roots is applied with an initial value x0=0, all approximates are so-called "best rational approximates"—in this case, of the form F2n/F2n+1, where Fn denotes the nth Fibonacci number. Recently this observation was extended by Komatsu to the class of all quadratic irrationals whose continued fraction expansions have period length 2. Here we generalize these observations by producing an analogous result for all quadratic irrationals and thus provide an explanation for this phenomena.

A well-known construction of associahedra comes from truncations of simplices. Motivated by compactifications of point configurations, we show associahedra as truncations of certain products of simplices. This is then used to provide a combinatorial construction of the real moduli space of spheres relating it to blow-ups of the braid hyperplane arrangement.

An algorithm is given for computing explicit formulas for the generators of relations among the invariant rational functions for vector-valued bilinear forms. These formulas have applications in the geometry of Riemannian submanifolds and in CR geometry.

Observations on the neurochemistry of dementia with Lewy bodies (DLB) have suggested that cholinesterase inhibitors (ChEIs) might be beneficial in treating some clinical symptoms of DLB. A 24-week, multicenter open-label study was designed to assess the safety and efficacy of the ChEI galantamine in patients with DLB, and an interim analysis of results was performed at 12 weeks. Efficacy analyses were performed on data from 25 patients. Scores on the Neuropsychiatric Inventory (NPI-12) improved (decreased) by 7.52 points over the 12 weeks (marginally significant, p = 0.061). NPI-12 scores decreased by half in 12 of the 25 patients. Highly significant improvement was observed in scores on the NPI-4 subscale (delusions, hallucinations, apathy, and depression: p = 0.003). Scores on the Clinician’s Global Impression of Change (CGIC) improved by 0.95 points (significant, p = 0.02). Improvements also were found in secondary efficacy variables, including cognitive, functional, activities of daily living, sleep and confusion assessments. Motor scores, as measured by the UPDRS motor subscale, showed mild improvement, which demonstrates that galantamine has no adverse effect on parkinsonian symptoms. Adverse events generally were transient and of mild-to-moderate intensity. Two of the 25 patients discontinued galantamine because of nausea and anorexia. One serious adverse event was recorded, but it was judged to be unrelated to the study medication.

In this paper, we show that a complete local ring T containing the integers is the completion of a local excellent integral domain if and only if it is reduced, equidimensional, and no integer of T is a zero divisor.

Let R be a local integral domain with maximal ideal M and S the domain R[X] localized at the ideal (M,X) where X is an indeterminate. In this paper, we explore the relationship between the dimension of the generic formal fiber of R and the dimension of the generic formal fiber of the domain S. Specifically, we show that if R is a universally catenary local domain such that the dimension of the generic formal fiber of S is dimR, then the dimension of the generic formal fiber of R is dimR – 1. We also provide counter-examples showing that the converse does not hold.

We add to the literature the well-known fact that an isoperimetric hypersurface S of dimension at most six in a smooth Riemannian manifold M is a smooth submanifold. If M is merely C1,1, then S is still C1,1/2.

We show that the periodic foams in equilibrium have periodic pressures. In addition, we show that a planar equilibrium foam with congruent bubbles must be a fully periodic arrangement of hexagons.

Illustrated response to a question about the existence of torus bubbles.

Here we prove that for any integers m and n, there exist infinitely many real and imaginary function fields K of degree m whose class groups each contain an abelian subgroup of order n.

We classify all factors of the Cartesian product of any two non-singular type III, 0 < 1, or type II1 Chacon transformations, as well as the centralizer of finite Cartesian products of such transformations.

We apply the algebraic construction due to Danylenko of (C,F) rank-one group actions to produce a number of rank-one infinite measure-preserving actions of countable discrete Abelian groups G with “unusual” multiply recurrence properties. In particular, we construct an action T of G such that for any non-torsion elements g1, ..., gn of G it is the case that the product transformation Tg1 x ... X Tgn is ergodic, p-recurrent but not (p+1)-recurrent. We also construct a p-polynomially recurrent action T that is not (p+1)-recurrent. Moreover, we show that there exists a (C,F)-transformation that is rigid (and hence multiply recurrent) but not polynomially recurrent. Nevertheless, the subset of polynomially recurrent transformations is generic in the group of infinite measure preserving transformations endowed with the weak topology.

We prove that a rank one transformation satisfying a condition called restricted growth is a mixing transformation if and only if the spacer sequence for the transformation is uniformly ergodic. Uniform ergodicity is a generalization of the notion of ergodicity for sequences, in the sense that the mean ergodic theorem holds for a family of what we call dynamical sequences. The application of our theorem shows that the class of polynomial rank one transformations, rank one transformations where the spacers are chosen to be the values of a polynomial with some mild conditions on the polynomials, that have restricted growth are mixing transformations, implying in particular Adams’ result on staircase transformations. Another application yields a new proof that Ornstein’s class of rank one transformations constructed using “random spacers” are almost surely mixing transformations.

We address the question: how large is the family of complete metrics with nonnegative sectional curvature on S2xR3? We classify the connection metrics, and give several examples of nonconnection metrics. We provide evidence that the family is small by proving some rigidity results for metrics more general than connection metrics.

We classify the complete metrics with nonnegative sectional curvature on M2xR2, where M2 is any compact 2-manifold.

When eukaryotic genes are edited by the spliceosome, the first step in intron recognition is the binding of a U1 small nuclear RNA with the donor (5’) splice site. We model this interaction thermodynamically to identify splice sites. Applied to a set of 65 annotated genes, our “Finding with Binding” method achieves a significant separation between real and false sites. Analyzing binding patterns allows us to discard a large number of decoy sites. Our results improve statistics-based methods for donor site recognition, demonstrating the promise of physical modeling to find functional elements in the genome.

Experiments have yielded multiple coexistence loops for gels with random positive and negative ionic groups, exhibiting the existence of up to seven distinct macroscopic phases distinguished by volume discontinuities. We introduce for this system a model composed of local degrees of freedom for ionization and for ionized cross-binding that are spatially arrayed with random connectivity. This model yields the multiple coexistence of phases, as well as volume versus excess charge curves, similar to the experimental results.

Spectral, temporal, and polarization resolved four-wave mixing measurements in a series of InGaAs heterostructures with varying well width reveal that mean-field Coulomb interactions between excitons are relatively insensitive to confinement.

“Treasures of the Past X: A Spectroscopic Determination of Scattering Lengths for Sodium Atom Collision”, a reprinting of J. Res. Natl. Inst. Stand. Technol. 101, 505 [1996], selected by the editors of the NIST Journal of Research as one of 10 papers representing the “breadth and excellence of work carried out at NIST” over the past 100 years.

In warped supersymmetric grand unification, XY gauge particles appear near the TeV scale along with Kaluza-Klein towers of the standard model gauge fields. In spite of this exotic low-energy physics, the successful gauge coupling unification prediction of the minimal supersymmetric standard model (MSSM) is preserved and proton decay is naturally suppressed. In this paper, we study in detail the low-lying mass spectrum of superparticles and grand unified particles in this theory, taking supersymmetry breaking to be localized to the TeV brane. The masses of the MSSM particles, Kaluza-Klein modes, and XY states are all determined by two parameters, one that fixes the strength of the supersymmetry breaking and the other that sets the scale of the infrared brane. A particularly interesting result is that for relatively strong supersymmetry breaking, the XY gauginos and the lowest Kaluza-Klein excitations of the MSSM gauginos may both lie within reach of the CERN Large Hadron Collider, providing the possibility that the underlying unified gauge symmetry and the enhanced N= 2 supersymmetry of the theory will both be revealed.

We study precision electroweak constraints on the close cousin of the littlest Higgs model, the SU(6)/ Sp(6) model. We identify a near-oblique limit in which the heavy W’ and B’ decouple from the light fermions, and then calculate oblique corrections, including one-loop contributions from the extended top sector and the two Higgs doublets. We find regions of parameter space that give acceptably small precision electroweak corrections and only mild fine-tuning in the Higgs potential, and also find that the mass of the lightest Higgs boson is relatively unconstrained by precision electroweak data. The fermions from the extended top sector can be as light as ~1 TeV, and the W’ can be as light as ~1.8 TeV. We include an independent breaking scale for the B’, which can still have a mass as low as a few hundred GeV.

We designed and constructed a simplified experimental system to create a Bose-Einstein condensate in 87Rb. Our system has several novel features including a mechanical atom transfer mechanism and a hybrid Ioffe-Pritchard magnetic trap. The apparatus has been designed to consistently produce a stable condensate even when it is not well optimized.

Let us accept the quantum mechanical description of a free particle and one fact from special relativity: rest mass contributes to energy. If we add to this bare framework one additional fact—that time runs slower near the earth—we can account for our everyday experience of gravity.

Focusing particularly on one-qubit and two-qubit systems, I explain how the quantum state of a system of n qubits can be expressed as a real function—a generalized Wigner function—on a discrete 2n x 2n phase space. The phase space is based on the finite field having 2n elements, and its geometric structure leads naturally to the construction of a complete set of 2n + 1 mutually conjugate bases.

A total of 411 children from urban and rural areas of Jamaica and from rural New England were examined by both White and Black interviewers for their skin color and body size preferences and for self-identification, using a modified dolls test. Overall, children from all three communities showed White favoritism and average body size favoritism. Within communities, there were age and gender differences. Kindergartners from rural Jamaica did not show skin color or body size bias, and White fifth/sixth graders from New England showed reverse, pro-Black and pro-chubby favoritism. In Jamaica, boys displayed more bias than girls did. Correct racial self-identification was greater among New England than Jamaican children, possibly related to the choice of White as an ideal self among some Jamaican children. Examiner skin color influenced both color and body size preference; self-identification was influenced by examiner skin color only among the rural Jamaican children.

Change in the adult identity of 155 participants from the Intergenerational Study, Institute of Human Development, was examined across a period of 24 years, and was related to theory-based life experiences and the use of defense mechanisms. The results indicated an increase in Achieved, Moratorium and Foreclosed Identity, and a decrease in Diffusion. As was expected from previous research and theory, identity change in middle adulthood and late middle age was predicted by use of the defense of identification. In addition, life experiences in the areas of work, marital and family relationships, social network, and political orientation were significantly related to identity and identity change. For both defenses and life experiences, IQ significantly moderated the predictions of identity change.

The association between maturity of defense use and psychological functioning was assessed in a group of 95 elementary school children. Defense mechanisms were measured using a valid and reliable storytelling task, and psychological adjustment was assessed through a combination of parent and self-report questionnaires. Correlational analyses indicated that children who relied on the developmentally immature defense of denial reported higher levels of self-rated social anxiety and depression and received higher ratings of parent-reported internalizing and externalizing behavior problems. However, children who made use of the developmentally mature defense of identification exhibited higher scores on perceived competence in social, academic, conduct, athletic, and global domains. Significantly, there was no relationship between children’s use of denial and their level of perceived competence or between children’s use of identification and their degree of maladjustment.

In a laboratory experiment, 72 participants who were guilty or innocent of a mock theft were apprehended for investigation. Motivated to avoid prosecution and trial, they were confronted by a neutral, sympathetic, or hostile male “detective” who sought a waiver of their Miranda rights. Later, 72 other participants watched videotapes of these sessions and answered questions about the detective and suspect. Strikingly, results showed that although the detective’s demeanor had no effect, participants who were truly innocent were significantly more likely to sign a waiver than those who were guilty. Naively believing in the power of their innocence to set them free, most waived their rights even in the hostile detective condition, where the risk of interrogation was apparent. The conceptual and policy implications of these results are discussed

The Massachusetts Supreme Judicial Court this month heard oral arguments on the question of whether to require police to videotape all custodial interrogations. For many reasons, such a policy is sensible, civilized, and necessary.

This study explores the relation between girls’ social adjustment and their use of defense mechanisms. We recruited girls representing four sociometric status classifications (rejected, neglected, average, and popular), and assessed their use of defense mechanisms both before and after encountering a peer rejection experience in the laboratory. We hypothesized that increasing degrees of social maladjustment would be associated with higher levels of defense use, particularly after encountering a rejection experience. Our results supported these hypotheses. There was a significant negative relationship between social adjustment and defense use, both prior to and immediately following the rejection experience. Categorical analyses revealed that rejected and neglected girls used more defenses following the rejection experience than did popular and average girls.

The association between maturity of defense use and psychological functioning was assessed in a group of 95 elementary school children. Defense mechanisms were measured using a valid and reliable storytelling task, and psychological adjustment was assessed through a combination of parent and self-report questionnaires. Correlational analyses indicated that children who relied on the developmentally immature defense of denial reported higher levels of self-rated social anxiety and depression and received higher ratings of parent-reported internalizing and externalizing behavior problems. However, children who made use of the developmentally mature defense of identification exhibited higher scores on perceived competence in social, academic, conduct, athletic, and global domains. Significantly, there was no relationship between children’s use of denial and their level of perceived competence or between children’s use of identification and their degree of maladjustment.

Elementary school children completed a daily diary indicating specific peer encounters that had occurred that day at school and participated in sociometric surveys. Diary items assessed three categories of negative peer encounters (physical victimization, social victimization, exclusion) and two categories of positive encounters (positive interactions, participation in activities). Psychometric analyses supported the distinction of these categories. Children’s reports of negative peer experiences were associated with their reputations as assessed by sociometric nominations (i.e., low social preference, aggression, withdrawal, and low leadership). Children who were poorly liked or viewed as exhibiting undesirable characteristics encountered more peer mistreatment, while children who were well liked or viewed as exhibiting positive characteristics encountered less. Children’s reports of positive encounters were not associated with their social reputations. Consistent with the premise that aggressive-rejected children experience a "kinder" social context than their less aggressive counterparts, aggressive-rejected boys reported fewer instances of negative treatment than withdrawn-rejected boys.

Objective: To examine the associations among disease status, social competence, and depressive symptoms in children with juvenile rheumatic disease (JRD) and to test the hypothesis that individual differences in children’s social competence account for a significant proportion of variance in depressive symptoms after controlling for disease status variables. Method: Thirty-six children with JRD completed standardized instruments to assess pain, health status, and depressive symptoms. The rheumatologist completed a disease severity measure, and teachers provided ratings of peer rejection and social behavior. Results: Pain, peer rejection, and problematic social behavior were all positively associated with depressive symptoms. Social variables remained significantly associated with depressive symptoms after controlling for level of pain. In addition, peer rejection moderated the association between pain and depressive symptoms, such that children with high levels of pain and high levels of peer rejection reported the highest frequency of depressive symptoms. Conclusions: Health care providers should assess the social functioning of children with JRD in order to identify socially vulnerable children who may be at increased risk for internalizing problems.

This study examines the reliability and validity of a newly developed self-report measure designed to assess children’s coping strategies in response to everyday rejection experiences. The Survey for Coping with Rejection Experiences (SCORE) was administered to 225 children and factor analysis of responses resulted in the conceptually meaningful subscales of active, aggressive, denial, and ruminative coping. A subset of 95 children also completed a battery of self- (depression, social anxiety), parent- (internalizing and externalizing problems), and peer- (social preference, aggression, withdrawal) ratings of socioemotional adjustment. Children’s coping strategies were meaningfully associated with adjustment measures, although these associations differed for boys and girls in several instances. Importantly, both aggressive and ruminative coping strategies were positively associated with internalizing problems even after controlling for the effect of children’s actual sociometric status. In addition, denial coping emerged as a significant moderator of the relation between status and adjustment.

Estradiol replacement to ovariectomized female rats causes dramatic changes in hippocampal structure and function as well as in performance on hippocampally-dependent tasks. Using a delayed matching-to-place version of the water maze, the present study examines the time course of estradiol-induced enhancements in memory retention as well as the effectiveness of acute and continuous patterns of replacement. One 10-mg injection of estradiol administered on each of two successive days resulted in significant improvements in memory retention that persisted for approximately 4 days following the second injection. When estradiol administration continued for 10 consecutive days, these improvements in memory retention persisted. These findings indicate that estradiol replacement can improve memory retention and that these improvements can be maintained by continuous replacement for at least 10 days.

Individuals often believe their internal states are more apparent to others than is actually the case, a phenomenon known as the illusion of transparency.  In the domain of public speaking, for example, individuals who are nervous about delivering a public speech believe their nervousness is more apparent to their audience than it actually is, a finding we document in Study 1.  We contend that the illusion of transparency can play a role in the self-exacerbating nature of speech anxiety, and show in Study 2 that an awareness of the illusion can improve the quality of a speaker’s performance, from both the speaker’s own perspective and in the eyes of observers.  Discussion focuses on the application of these findings to the treatment of speech anxiety and other forms of social anxiety.

This research provides evidence that people overestimate the salience to others of their own absence from a group. Although individuals regard the removal of someone else from a group to be less salient than the addition of that person, they regard their own removal as every bit as salient as their addition (Study 1). Those absent from a group also expect their absence to be salient in the eyes of others, overestimating the extent to which their absence will be noticed by others (Study 2), and rating their absence as having had a larger impact on the group’s subsequent functioning than others do (Study 3). Discussion focuses on individuals’ assessments of their absence as an example of a broader egocentrism in social judgment.

Krueger and Funder (2004) make the familiar accusation that social psychologists focus too much on what people do wrong, rather than on what they do right. Although there is some truth to their charge, their accusations are overstated and their conclusions are incorrect. The field is far less problem-focused than they suggest, and the proposed consequences of this approach are more imagined than real.

This chapter addresses several important aspects of competence in Japan, using the United States as a point of comparison. Both Japanese and Americans treat intellectual qualities as central to the meaning of competence; however, Japanese are shown to be somewhat more sensitive to the relevance of attitudinal and interpersonal qualities. The developmental trajectory of culturally appropriate competence is discussed, including the mother’s role in competent child rearing, the link between scholastic achievement and culturally appropriate competence, and stability in the concept of competence across the lifespan. Overall, juxtaposing the assumptions and practices of Americans and Japanese highlights the fact that achieving success in many real-world tasks depends not only on the mind, but on the heart as well.

Self-complexity (SC) theory proposes that a highly differentiated self-concept protects against the depressogenic impact of negative life events. Linville’s influential prospective study appeared to support this proposition (P. W. Linville, 1987). Subsequent reports have raised questions about the construct validity of Linville’s operationalization of self-complexity (defined by the degree to which self-reported personality descriptors are dispersed across self-aspects), as well as the robustness of a buffering effect of self-complexity. In the present replication, Linville’s SC measure was again found to moderate the impact of stress on depressive symptoms. However, contrary to SC theory, the form of the Stress Å~ SC interaction was not clearly consistent with stress protection. Also contrary to SC theory, the interaction of stress and SC was entirely explained by the number of self-descriptive personality traits endorsed in the SC task. Both of these findings suggest that with regard to depressive symptoms, reports of a stress-buffering effect for self-complexity are premature.

Recent reviews of cognitive theories of depression have noted that individualized assessment strategies might help to resolve mixed findings regarding the stability of depressotypic beliefs and attitudes. We describe encouraging results for an individualized measure of one such cognitive construct, irrational beliefs. Twenty depression-prone women (recurrent major depressives in full remission) and twenty closely matched never-depressed controls completed leading forced-choice measures of irrational beliefs (the Belief Scale; BS) and sociotropy-autonomy (The Revised Personal Style Inventory), as well as the Specific Demands on Self Scale (SDS). The BS requires participants to rate their agreement with twenty preselected statements of irrational beliefs, while the SDS focuses on whether participants harbor any strongly held irrational beliefs, even if uncommon or idiosyncratic. Consistent with previous research, there were no group differences on the traditional measure of irrational beliefs. In contrast, depression-prone participants strongly exceeded controls on the SDS, and this difference persisted after controlling for residual depression, anxiety symptoms, anxiety diagnoses, sociotropy, and autonomy. These findings provide some initial support for a key assumption of the rational-emotive model of depression, and, more broadly, suggest that individualized assessment strategies may help researchers capture the core negative beliefs of asymptomatic individuals, even in the absence of mood or cognitive priming.

In a recent article, J. P. Minda and J. D. Smith (2002) argued that an exemplar model provided worse quantitative fits than an alternative prototype model to individual subject data from the classic D. L. Medin and M. M. Schaffer (1978) 5/4 categorization paradigm. In addition, they argued that the exemplar model achieved its fits by making untenable assumptions regarding how observers distribute their attention. In this article, we demonstrate that when the models are equated in terms of their response-rule flexibility, the exemplar model provides a substantially better account of the categorization data than does a prototype or mixed model. In addition, we point to shortcomings in the attention-allocation analyses conducted by J. P. Minda and J. D. Smith (2002). When these shortcomings are corrected, we find no evidence that challenges the attention-allocation assumptions of the exemplar model.

In 2 sets of experiments, the authors investigated the basis for old-item distinctiveness effects in perceptual recognition, whereby distinctive old items are recognized with higher probability than are typical old items. In Experiment 1, distinctive old items were defined as those lying in isolated regions of a continuous-dimension similarity space. In this case, any beneficial effects of distinctiveness were absent or small, regardless of the structure of the test list used to assess recognition memory. In Experiment 2, distinctive items were defined as those objects containing certain discrete, individuating features. In this case, large old-item distinctive effects were observed, with the nature of the effects being modulated by the structure of the test lists. A hybrid-similarity exemplar model, combining elements of continuous-dimension distance and discrete-feature matching, was used to account for these distinctiveness effects in the recognition data.

In many species, infant mammals vocalize when separated from their caregivers in order to elicit protection, nourishment, or warmth. These “cries” are theorized to aid in the formation of the maternal-infant bond. When separated from its dam, the infant rat produces ultrasonic vocalizations (USVs) typically in the range of 30-90 kHz, which can direct maternal care. In this laboratory, an “early deprivation” (also called “maternal separation”) paradigm is used to model child neglect. Rat pups between 2 and 6 days of life were separated from their dams for 6 hours a day in individual, temperature-controlled chambers. Control rats remained in non-disturbed litters. At 7 days of age, recordings were made of USVs emitted by pups with a prior history of early deprivation or controls during a semi-naturalistic test of brief maternal separation. Results indicate that previously separated rats emit fewer vocalizations than controls, although they received more maternal care. Analyses of sonograms found that significant differences in the calls could be detected in terms of degree of frequency modulation, number of missing harmonics, and inter-bout intervals. USVs may provide a good model system to determine neural mechanisms underlying deficits in attachment behavior and possibly depression in children with histories of neglect.