cssi/SciSciGPT-SciSciNet huggingface dataset:
High-precision in situ 238U–234U–230Th isotopic analysis using laser ablation multiple-collector ICPMS

We have developed a method for the rapid, in situ measurement of U–Th isotopic compositions at the semimicro scale using laser ablation sampling, combined with multiple collector ICP magnetic sector mass spectrometry (MC-ICPMS). The system uses a Q-switched and frequency quadrupled 266 nm Nd:YAG laser to ablate samples containing 100 ppm levels of U at 150 μm scale resolution, corresponding to 1–4 ng 238U, ∼70–200 fg of 234U and 20–60 fg of 230Th consumed per analysis. Synthetic glass standards and naturally occurring samples of zircon and opal, with U contents of 460, 260, and ∼200 ppm, respectively, were used to assess the precision and accuracy of our laser ablation technique. Our initial experiments used argon as the plasma support gas. Thirty-seven laser analyses on the glass and 29 on the zircon give respective mean [234U/238U]act of 0.17114 ± 0.00022 and 1.0018 ± 0.0014 (2σM), indistinguishable from the MC-ICPMS solution nebulization values of 0.17094 ± 0.00006 and 1.0011 ± 0.0009 (2σM), respectively. The usual within-run precision obtained for both glass and zircon is ±3‰ at the 2σM level. An additional 12 laser analyses on the opal give a mean [234U/238U]act of 0.9997 ± 0.0034, in excellent agreement with the expected secular equilibrium value of unity and a typical within-run precision of ±8‰ (2σM). Our Nd:YAG laser, coupled with an all Ar gas system, produces large elemental fractionation effects between U and Th. Both 238U/232Th and [230Th/238U]act can be measured at the per mill level, but Th ion beams are suppressed relative to U. As a result, the Th/U ratios are systematically lower, and the apparent 238U–234U–230Th ages are systematically younger than the true values. The U–Th fractionation is primarily controlled by ionization conditions in the plasma, transportation efficiency of ablated particles, and the composition of the sample matrix. The use of helium instead of Ar in the ablation cell significantly improves the relative sensitivity of Th, and entirely eliminates the elemental fractionation between U and Th, while retaining accuracy and precision in U isotope measurement. With He, mean values for [230Th/238U]act of 0.996 ± 0.013 and 238U/232Th of 1.625 ± 0.092 were determined for the zircon standard, in excellent agreement with the solution nebulization values of 1.0042 ± 0.0016 and 1.6288 ± 0.0006 (2σM), respectively. In an unknown sample, it is possible to determine correct values for [230Th/238U]act and 238U/232Th, with respective within-run uncertainties as good as 7‰ and 2‰, by monitoring the isotopic composition of a well characterized, matrix-matched standard. For high-U material, the combined uncertainties in [234U/238U]act and [230Th/238U]act routinely translate to 2σM errors in the 238U–234U–230Th age of better than ±2,500 years in 100,000-year-old samples.
The influence of ATP on glycogen synthetase D phosphatase activity in liver

Abstract 1. 1. A number of compounds from pathways associated with glucose and glycogen metabolism have been evaluated as regulators of the liver synthetase D phosphatase reaction. Although several were found to be inhibitory to the reaction, only ATP was an effective inhibitor at physiological concentrations. 2. 2. The inhibition by ATP was not a manifestation of either a stimulation of synthetase kinase or phosphoryllase kinase or the inhibition of phosphorylase phosphatase. All of these effects could result in an apparent inhibition of synthetase phosphatase. Whether the effect of ATP is on synthetase phosphatase or synthetase D, its substrate, is as yet unknown.
Sources of HCl and HF in the Atmosphere of Venus

RECENT planetary probe measurements within the atmosphere and in the near vicinity of Venus1,2 make possible further interesting correlations between the physical conditions and the chemistry of the atmosphere and lithosphere. It is particularly interesting to see whether the recently reported abundances of HCl and HF in the atmosphere3 are compatible with the chemical interaction model which was proposed earlier4,5 to account for the other atmospheric constituents.
Hydrogen bonding Part 56. IR spectra and stoichiometry of the hydrates of N-methyltriethylenediamine cation halides and hydroxide

Abstract We have prepared the N -methyltriethylenediamine cation bromide hemihydrate, chloride monohydrate, fluoride monohydrate and hydroxide dihydrate. These salts show no propensity to form higher crystalline hydrates. There is no indication of H 2 O to cage nitrogen hydrogen bonding, as was previously observed for the iodide monohydrate. Combination of IR and thermodynamic information demonstrates that the bromide and iodide hemihydrates have the same water—halide structure. Since the bromide hemihydrate does not contain (H 2 O·Br − ) 2 clusters, we conclude that the iodide hemihydrate does not contain (H 2 O·I − ) 2 clusters, as previously postulated. Both the bromide and iodide hemihydrates are presumed to contain C 2v X − ⋯ HOH ⋯ X − groupings. The chloride and fluoride monohydrates contain planar (H 2 O·X − ) 2 clusters. The hydroxide monohydrate could not be prepared; the dihydrate decomposes slowly on further dehydration, presumably by S N 2 attack of OH − on the methyl group.
An exact method for the computation of the connectivity of random nets

The problem of finding the “weak connectivity” of a random net is reduced to one involving a Markov process. This provides a mathematically exact treatment of the problem which had previously been treated by an approximation, whose justification was not rigorous. The exact method allows in principle not only the calculation of the “weak connectivity”, but also of the “strong connectivity”, and, in general, the probability that from a randomly selected neuron in the net there exist paths to a specified number of neurons. The computations become exceedingly involved for large nets.
Mathematical modeling and efficient optimization methods for the distance-dependent rearrangement clustering problem

In this article we present a computational study for solving the distance-dependent rearrangement clustering problem using mixed-integer linear programming (MILP). To address sparse data sets, we present an objective function for evaluating the pair-wise interactions between two elements as a function of the distance between them in the final ordering. The physical permutations of the rows and columns of the data matrix can be modeled using mixed-integer linear programming and we present three models based on (1) the relative ordering of elements, (2) the assignment of elements to a final position, and (3) the assignment of a distance between a pair of elements. These models can be augmented with the use of cutting planes and heuristic methods to increase computational efficiency. The performance of the models is compared for three distinct re-ordering problems corresponding to glass transition temperature data for polymers and two drug inhibition data matrices. The results of the comparative study suggest that the assignment model is the most effective for identifying the optimal re-ordering of rows and columns of sparse data matrices.
On the generality of correlation of atmospheric aerosol mass concentration and light scatter

Abstract A series of simultaneous mass concentration and light scattering measurements has been conducted in several locations with widely varying types and amounts of aerosol. The results indicate that the relationship between mass concentration and the extinction coefficient due to scatter is the same for all locations. The approximately constant proportionality implies that the size distribution of the aerosol is relatively reproducible. If the results are put into the form of the product of meteorological range and mass concentration, the mass of material necessary to determine the meteorological range is distributed about a modal value of 1.2 g m −2 .
Dietary choices of people with ostomies

Abstract Objective: The objective was to collect data related to individual dietary recommendations and restrictions for people with ostomies. Design: A descriptive survey was used that asked people about food choices/avoidances that occurred because of their ostomy. Subjects: Subjects were members of the United Ostomy Association who had an ostomy and were living at home. Methods: A 14-item questionnaire was mailed to the United Ostomy Association membership (approximately 40,000 current members) in their quarterly newsletter. Results: Six hundred and four questionnaires were returned. The most frequent reason for ostomy surgery among the respondents was colon cancer (71%; n = 424), and the most common type of ostomy was a colostomy. The majority of respondents (88.4%) stated that they were not following a special diet because of the ostomy; 11.8% (n = 69) stated that they had modified their diet. Of the people who had modified their diet, 55% stated that they were using the special diet indefinitely and were adhering to it very well. More than half of the participants had received dietary instructions, provided mainly by a WOC nurse, at the time of surgery. The foods avoided because of the ostomy included fresh fruits, nuts, coconut, and vegetables such as corn, popcorn, cabbage, beans, and onions. The major problems reported were blockage and increased gas. Conclusion: Many respondents reported problems with certain foods. Preoperative teaching and postoperative follow-up must include anticipatory guidance on food selection.
Acoustic and Hydrodynamic Response of an Annular Cascade to Inflow Disturbances in Swirling Flows

A model is developed for the interaction of high frequency inflow disturbances with an annular cascade in swirling flows. The computational domain is decomposed into inner and outer subdomains. The outer subdomain scales with the radius of the duct R and the high frequency approximation is used to simplify the governing equations. The inner subdomain scales with the blade chord c << R, and the mean flow variation due to the blade geometry has significant effects on the solution. The numerical results show that for swirling mean flows, as the rotor-stator spacing increases the unsteady blade pressure and the level of acoustic radiation are first reduced. However, further increasing the spacing to more than 2–3 chord lengths produces no significant change. The spanwise variation of the swirl angle (blade twist) has significant effects on the spanwise unsteady lift distribution and propagating acoustic pressure. Spanwise modulation of the incident gust reduces the unsteady lift considerably.Copyright © 2003 by ASME
The effects of methylparaben on the gelatinization and thermal decomposition of corn starch

The effects of methylparaben, frequently used preservative, on the gelatinization and solid state decomposition of corn starch were determined. It was observed that methylparaben causes a decrease in the gelatinization temperature of the starch by up to 14.8°C. The starch was shown to degrade in two consecutive reactions, an initial dehydration, followed by the formation of a carbonaceous residue. The decomposition was altered by the methylparaben, as suggested by an increase in the temperature of the dehydration reaction, indicating that a higher temperature was required to drive off the bound water. The activation energy for the major decomposition was also higher when the preservative was present. The methylparaben was shown to evaporate via a zero-order kinetic process, with an increasing activation energy in the presence of corn starch. The melting point was unaffected.
Fully sampled 3600 element two dimensional transducer array for low cost C-scan imaging

Preliminary results relating to the design, fabrication, and characterization of a 3600 (60 x 60) element, fully sampled, 5 MHz two dimensional (2D) array are presented. The viable element yield of the new array was estimated at 98.3%. Single-element pulse-echo experiments indicate that the center frequency is 4.7 MHz - 7.8% below the resonant frequency determined by Finite Element Analysis (FEA) simulation. Pulse-echo signal fractional bandwidth was measured to be 60.3% at the -6 dB level. Ringdown was longer than anticipated in experimental pulse echo voltage waveforms, which we attribute in part to a lack of matching layer and a low-loss backing material. Based on plane-wave pulse-echo experiments in a water-tank, single element signal-to-noise ratio (SNR) was calculated to be 6.0 when using a plane-wave transmit (all elements excited). Experimental angular beam patterns were more directional than predicted with the standard soft-baffle equation, but in good agreement with FEA simulations that take account of finite acoustic crosstalk.
Motion of dust in a planetary magnetosphere - Orbit-averaged equations for oblateness, electromagnetic, and radiation forces with application to Saturn's E ring

The orbital dynamics of micrometer-sized dust grains is explored numerically and analytically, treating the strongest perturbation forces acting on close circumplanetary dust grains: higher-order gravity, radiation pressure, and the electromagnetic force. The appropriate orbit-average equations are derived and applied to the E ring. Arguments are made for the existence of azimuthal and vertical asymmetries in the E ring. New understanding of the dynamics of E ring dust grains is applied to problems of the ring's breadth and height. The possibility for further ground-based and spacecraft observations is considered.
Estimate optimization parameters for incoherent backscatter heterodyne lidar including unknown return signal bandwidth.

The conditions for optimizing the precision of heterodyne atmospheric lidar measurements using extended (deep) targets are investigated. The minimum standard deviation of each unknown (return power, Doppler shift, and signal bandwidth) is approximately twice the optical limit at best and is only weakly dependent on knowledge of the other parameters at optimal power levels. Somewhat stronger signal power levels are needed for bandwidth estimation. Results are displayed as a function of a time–bandwidth product to clarify the trade-off between estimate precision and range weighting. Realization under ideal conditions is confirmed by use of simulations.
Chicken or egg? Sequential complementarity among salesforce control mechanisms

Firms struggle with salesforce control, particularly as typical piecemeal approaches overlook the nuance that the effect of a control is amplified or muted by a context created by other simultaneously deployed controls. Recent studies showing interactions between formal controls caution that control mechanisms must be examined as a portfolio. This study takes the next step in addressing how widely-studied formal controls interact with understudied input control and informal control in a salesforce control portfolio. We introduce the idea of sequential complementarity—when deploying a control mechanism enhances marginal returns from increasing a temporally preceding one—within a control portfolio to explain those interactions. We use data from 120 apparel manufacturers and 94 retailers to show that the performance benefits of formal control mechanisms depend on precedence by input control. These effects flip in the presence of informal control. Our unique contribution is theoretically introducing temporality into “holochronic” control theory to explain interactions of formal with informal control mechanisms.
Nature of the low-field transition in the mixed state of high-temperature superconductors

We have numerically studied the statics and dynamics of a model three-dimensional (3D) vortex lattice at low magnetic fields. For the statics we use a frustrated 3D XY model on a stacked triangular lattice. We model the dynamics as a coupled network of overdamped resistively shunted Josephson junctions with Langevin noise. At low fields, there is a weakly first-order phase transition, at which the vortex lattice melts into a line liquid. Phase coherence parallel to the field persists until a sharp crossover, conceivably a phase transition, near T{sub scr(l)}{gt}T{sub m} which develops at the same temperature as an {ital infinite} vortex tangle. The calculated flux flow resistivity in various geometries near T=T{sub scr(l)} closely resembles experiment. The local density of field induced vortices increases sharply near T{sub scr(l)}, corresponding to the experimentally observed magnetization jump. We discuss the nature of a possible transition or crossover at T{sub scr(l)}(B) which is distinct from flux lattice melting. {copyright} {ital 1998} {ital The American Physical Society}
Above cloud electrical discharges : The effect of aerosol transport

Upward-propagating discharges from thunderstorms, called “blue jets” and “blue starters” and high altitude near-cloud top discharges have been reported over strong convective storm systems. The electrodynamics involved in these high altitude electrical phenomena are not clarified, though several models have been proposed, including initiation by run-away high energy electron beams and breakdowns related to quasi-electrostatic fields. We suggest that the occurrence of such high altitude discharges may, under some conditions, be instigated by decreases in electrical conductivity (and therefore increases in electric field strength) near and above cloud tops, the conductivity decrease resulting from the presence of large ions. We hypothesize that the large ions are pollution aerosols which are systematically transported to the lower stratosphere/upper troposphere from the lower troposphere by convective currents. In addition we propose that large ion production in the region above cloud is further enhanced by: 1. creation of new large ions by photolytic gas-to-particle conversion; and 2. by the upward transport of cloud top ions across the tropopause into the lower stratosphere.
Beyond the bubbles: Creative New York in boom, bust and the long run

Abstract Both production-centered and more consumption-oriented theorists have speculated that in the wake of the 2008 financial crash, the creative industries will replace finance as an economic driver in major cities. One advantage of the productionist account is that it is inclined to analyze a wider range of social and institutional factors. This paper assesses the consequences of the crash for cultural and creative industries (CCIs) in New York City by drawing on the productionist approach and extending its consideration of the context of creativity to include speculative cycles and policy responses. The paper finds that while the CCI have taken an increasing role in the New York economy in the long term, they have been more vulnerable than the rest of the economy in the immediate aftermath of the crash. It also shows the importance of context in good as well as bad times. Those CCI that were most directly linked to particular episodes of financial speculation had the most explosive rises during boom and the most dramatic falls when the boom ended. In addition, specific industrial conditions (e.g., digitalization, tourism) can constrain growth in a CCI segment during a boom, or conversely, provide a boost even after the boom ends. Regarding policy responses, the paper finds that federal interventions buffered New York’s economy temporarily while the city has experimented with more active support of some CCI, namely media and fashion. This suggests that the post-crash fate of New York’s CCI is not yet settled.
Detrital Heavy Minerals of Upper Triassic Sandstones of West Texas: ABSTRACT

Heavy-mineral analysis of 53 outcrop samples from the Upper Triassic Dockum Group in West Texas and northeastern New Mexico showed a stable heavy-mineral association of zircon, tourmaline, garnet, leucoxene, magnetite-ilmenite, and rutile. An adjacent sedimentary source terrane was suggested by these results. Previous studies of cross-bedded Dockum sandstones indicated a source for the Upper Triassic at the southeast. Fifteen outcrop samples were therefore examined from sandstones of Pennsylvanian and Permian age in central Texas, the assumed source area. Both heavy minerals and quartz varieties in these rocks were virtually the same in most details as those of the Dockum Group. Comparisons of mineral varieties and their roundness characteristics also indicated close similarities. It is concluded that: (1) mineralogical comparisons corroborate cross-bedding results of a major source of detritus for the Upper Triassic at the southeast, (2) this source area was the sedimentary terrane consisting of clastics of Pennsylvanian and Permian age in central Texas, (3) more than one sedimentary cycle was involved, and (4) the probable ultimate source was a granitic terrane with minor basic igneous and metamorphic contributions. End_of_Article - Last_Page 352------------
Vector Based Kinematics

To find the positions and velocities of every point at which a force acts, the angular velocities of every body on which a torque acts, and the accelerations of every mass center.
Prognostic Degradation Models for Computing and Updating Residual Life Distributions in a Time-Varying Environment

This paper presents a degradation modeling framework for computing condition-based residual life distributions of partially degraded systems and/or components functioning under time-varying environmental and/or operational conditions. Our approach is to mathematically model degradation-based signals from a population of components using stochastic models that combine three main sources of information: real-time degradation characteristics of component obtained by observing the component's in-situ degradation signal, the degradation characteristics of the component's population, and the real-time status of the environmental conditions under which the component is operating. Prior degradation information is used to estimate the model coefficients. The resulting generalized stochastic degradation model is then used to predict an initial residual life distribution for the component being monitored. In-situ degradation signals, along with real-time information related to the environmental conditions, are then used to update the residual life distributions in real-time. Because these updated distributions capture current health information and the latest environmental conditions, they provide precise lifetime estimates. The performance of the proposed models is evaluated using real world vibration-based degradation signals from a rotating machinery application.
The Apache Longbow-Hellfire Missile Test at Yuma Proving Ground: Ecological Risk Assessment for Missile Firing

ABSTRACT A multiple stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework. The focus was a testing program at Cibola Range, which involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, that is, M60-A1 tanks. This article describes the ecological risk assessment for the missile launch and detonation. The primary stressor associated with this activity was sound. Other minor stressors included the detonation impact, shrapnel, and fire. Exposure to desert mule deer (Odocoileus hemionus crooki) was quantified using the Army sound contour program BNOISE2, as well as distances from the explosion to deer. Few effects data were available from related studies. Exposure-response models for the characterization of effects consisted of human “disturbance” and hearing damage thresholds in units of C-weighted decibels (sound exposure level) and a distance-based No-Observed-Adverse-Effects Level for moose ...
EDHF-mediated vasodilation involves different mechanisms in normotensive and hypertensive rat lungs.

The role of endothelium-derived hyperpolarizing factor (EDHF) in regulating the pulmonary circulation and the participation of cytochromeP-450 (CYP450) activity and gap junction intercellular commu...
The Dragon in the Land of Snows: A History of Modern Tibet Since 1947

Based entirely on unpublished primary sources, this remarkable book -the first authoritative history of modern Tibet - is also the first to provide detailed accounts of: * The covert political manoeuverings in Tibet and the role of the Tibetan, Chinese and British governments; * The Dalai Lama's escape in 1959; * The CIA's involvement and the establishment of a secret military base in the Nepalese Himalayas; * The British government lying to the UN and Douglas Hurd's role in that process; * The power struggles during th Cultural Revolution and the mass uprising against the Chinese that has remained secret until now.
Bayesian inference for prevalence and diagnostic test accuracy based on dual-pooled screening

We propose a useful protocol for the problem of screening populations for low-prevalence characteristics such as HIV or drugs. Current HIV screening of blood that has been donated for transfusion involves the testing of individual blood units with an inexpensive enzyme-linked immunosorbent assay test and follow-up with a more accurate and more expensive western blot test for only those units that tested positive. Our cost-effective pooling strategy would enhance current methods by making it possible to accurately estimate the sensitivity and specificity of the initial screening test, and the proportion of defective units that have passed through the system. We also provide a method of estimating the distribution of prevalences for the characteristic throughout the population or subpopulations of interest.
AFM image based pattern detection for adaptive drift compensation and positioning at the nanometer scale

The key function of AFM is to control the position of the probe according to imaging operation modes. These imaging modes yield multiple channels of data representing various probe responses to the same sample pattern. An algorithm based on the spatial and temporal correlation of the multiple channel data, corresponding to the same surface patterns, was developed to derive the pattern position with sub-pixel resolution in real time. This precise measurement of the pattern location serves as an input to an estimator of the drift velocity. An auxiliary position control was applied to compensate the drift between the probe tip and the sample. This pattern location measurement has higher noise rejection than any individual channel of the image, providing a reference location for drift compensation. Experimental data with sub nanometer drift control and nanoasperity measurements based on the auxiliary positioning are presented.
All-trans β-Carotene Appears to Be More Bioavailable than 9-cis or 13-cis β-Carotene in Gerbils Given Single Oral Doses of Each Isomer

Male gerbils (28 d old) were used to investigate the beta-carotene (betaC) isomer pattern in the intestine and tissues 6 h after ingestion of three betaC isomers. After a 49- to 52-d period of consuming the AIN93G diet without vitamin A (VA) or betaC, three groups (n = 7) were gavaged with crystalline all-trans (at)betaC, 9-cis (9c)betaC or 13-cis (13c)betaC solubilized in oil and a control group (n = 5) with oil alone. Total betaC per dose for gerbils in the atbetaC, 9cbetaC and 13cbetaC groups was 384 +/- 3, 391 +/- 2 and 386 +/- 2 nmol, respectively. After 6 h, gerbils were killed and serum, stomach contents, small intestinal contents (SIC), small intestinal mucosal scrapings (SIM) and liver were collected. betaC and VA in tissues were quantified using HPLC. Nonspecific isomerization of betaC occurred in the digestive tracts of gerbils administered betaC; the greatest effect was in the SIC of the 13cbetaC (50:50 cis:trans) and 9cbetaC (70:30 cis:trans) groups. Concentrations of total betaC in the SIM of gerbils administered at betaC were greater than those intubated with 9cbetaC and 13cbetaC (P < 0.05). Gerbils that received atbetaC had greater total betaC concentrations in serum (P < 0.05) and total betaC stores in liver (P < 0.01) compared with those administered 9cbetaC and 13cbetaC. Gerbils intubated with 9cbetaC had higher levels of total betaC in serum (P = 0.05) and liver (P < 0.01) compared with those intubated with 13cbetaC. Because of its preferential uptake, transport and tissue accumulation, atbetaC appears to be a more bioavailable isomer than 9cbetaC or 13cbetaC in gerbils.
Crossing Networks and Dealer Markets: Competition and Performance

This paper studies the interaction between dealer markets and a relatively new form of exchange, passive crossing networks, where buyers and sellers trade directly with one another. We find that the crossing network is characterized by both positive ~“liquidity”! and negative ~“crowding”! externalities, and we analyze the effects of its introduction on the dealer market. Traders who use the dealer market as a “market of last resort” can induce dealers to widen their spread and can lead to more efficient subsequent prices, but traders who only use the crossing network can provide a counterbalancing effect by reducing adverse selection and inventory holding costs. COMPETITION BETWEEN EXCHANGES for order f low is a growing phenomenon in financial markets. From London to Paris to Tel Aviv, exchanges and trading systems are introducing new trading mechanisms that compete for order f low. In the United States, the SEC promulgated new rules that redefine the regulation of Alternative Trading Systems and intensify the competition between existing exchanges and new electronic markets. Indeed, new electronic trading venues are cited as the reason for a decline in the value of seats on major exchanges, even though trading volumes are growing rapidly. What will be the impact of new trading mechanisms on market participants and on existing dealer markets ~DMs!? In this paper we study the effect of introducing a passive call market that competes with an existing traditional DM. The DM is based on competing market makers as in Nasdaq, the London Stock Exchange, the Foreign Exchange market, and the U.S. government securities market. An important benefit provided by the DM is the assurance of immediate execution. An important disadvantage is the cost: the bid-ask spread, which can be substantial. Traders who do not place a high value on immediacy and assured execution can try to reduce their trading costs by searching for counterparties on their own. As computing and communication costs have declined, electronic communication networks have been increasingly deployed to reduce search costs, making it less costly for traders to find one another and reducing the demand for DMs.
Response of beta diversity to pulses of Ordovician-Silurian mass extinction

Ecologists are increasingly using the fossil record of mass extinction to build predictive models for the ongoing biodiversity crisis. During mass extinctions, major depletions in global (i.e., gamma) diversity may reflect decrease in alpha diversity (i.e., local assemblages support fewer taxa), and/or decrease in beta diversity (such that similar pools of taxa are common to a greater number of local areas). Contrasting the effects of extinction on alpha and beta diversity is therefore central to understanding how global richness becomes depleted over these critical events. Here we investigate the spatial effects of mass extinction by examining changes in alpha, beta, and gamma diversity in brachiopod communities over both pulses of Ordovician-Silurian extinction (~445.2 and ~438.8 million years ago), which had dramatically different causal mechanisms. We furthermore reconstruct geographic range sizes for brachiopod genera to test competing models for drivers of beta diversity change. We find that: (1) al...
Classroom environments and the stratification of pupils' ability perceptions.

Rosenholtz and Simpson have suggested that the task structures, ability grouping practices, and evaluation practices present in a classroom are important determinants of the degree to which children's ability perceptions become stratified within the classroom. The effects of classroom practices on stratification of pupils' self-perceptions of math ability were estimated in 67 upper elementary math classes from schools in predominantly white, middle-income communities. The results suggest that the effects of task structure depend on the "talent dispersion" (actual dispersion of ability levels) in the class. In classes in which talent dispersion was high, differentiated task structures were associated with lower levels of stratification than were undifferentiated task structures. This effect disappeared in classes in which talent dispersion was low. The dispersion of report card grades, but not the frequency and emphasis of grading, was positively related to stratification. The implications of the results for educational theory and practice arc discussed. In one recent investigation, only 36% of a fifth- and sixthgrade sample indicated that they would "probably" or "definitely" take more math "if they didn't have to" (Achievement Research Laboratory, 1986). One reason why some pupils want to avoid mathematics is that they believe that they are poor at the subject (Eccles & Wigfield, 1985). Do certain classroom practices increase the likelihood that children will decide that they are poor at math? What classroom factors promote the development of large differences in pupils' ability perceptions so that some believe that they are "math whizzes" and others feel hopelessly incompetent? Why do pupils in some classes develop ability perceptions that tend to agree with their teacher's perceptions of them, whereas in other classes even pupils who the teacher thinks are untalented somehow maintain enough confidence in their ability to continue persevering in math? In this study I tested possible answers to these questions by examining the relation between certain features of the classroom environment (task structures, grading practices, and grouping patterns) and the stratification of children's self-perceptions of math ability.
Is Tail-Optimal Scheduling Possible?

This paper focuses on the competitive analysis of scheduling disciplines in a large deviations setting. Although there are policies that are known to optimize the sojourn time tail under a large class of heavy-tailed job sizes e.g., processor sharing and shortest remaining processing time and there are policies known to optimize the sojourn time tail in the case of light-tailed job sizes e.g., first come first served, no policies are known that can optimize the sojourn time tail across both light-and heavy-tailed job size distributions. We prove that no such work-conserving, nonanticipatory, nonlearning policy exists, and thus that a policy must learn or know the job size distribution in order to optimize the sojourn time tail.
A note on the new 1-D and 2-D stability theorems for discrete systems

An interesting theorem on the stability of 1-D discrete systems has been presented in [1] and it has been extended to the 2-D case in [2]. In this correspondence, after showing that the conditions stated by the theorems of [1] and [2] are only necessary, we introduce another condition, inclusion of which makes the above stability theorems necessary and sufficient.
Hot-Carrier- and Constant-Voltage-Stress-Induced Low-Frequency Noise in Nitrided High- $k$ Dielectric MOSFETs

Understanding and minimization of low-frequency noise (LFN) originating from high- k (HK) gate dielectrics in new generation MOSFETs are of critical importance to applications in RF, analog, and digital circuits. To understand the effect of stress conditions on noise, nMOSFETs were subjected to accelerated hot-carrier stress (HCS) and positive constant-voltage stress (CVS). The additional LFN introduced through stressing was evaluated on nMOSFETs with TiN metal gate and HfSiON gate dielectric. Nitridation of HfSiO gate-dielectric MOSFETs was achieved by either a high-temperature NH3 anneal or a lower temperature plasma anneal. Influence of different dielectric nitridation procedures on the stress-induced degradation of transconductance, threshold properties, and LFN was studied. Worst degradation conditions, i.e., Vg = Vd, were used for HCS, whereas for CVS, the vertical field was fixed at 10 MV/cm for all transistors to achieve comparable stressing conditions. Plasma-nitrided devices showed less increase in their noise in the linear operation region than the thermally nitrided devices. This difference in noise behavior is attributed to the nitrogen profile across the HK/Si interface and in the bulk of the HK oxide caused by different nitridation techniques. The dielectric defect profile resultant from different annealing techniques was consistent with the spectral form of the observed drain-voltage LFN.
How to Obtain Reproducible Results for Lithium Sulfur Batteries

The basic requirements for getting reliable Li-S battery data have been discussed in this work. Unlike Li-ion batteries, electrolyte-rich environment significantly affects the cycling stability of Li-S batteries prepared and tested under the same conditions. The reason has been assigned to the different concentrations of polysulfide-containing electrolytes in the cells, which have profound influences on both sulfur cathode and lithium anode. At optimized S/E ratio of 50 g L-1, a good balance among electrolyte viscosity, wetting ability, diffusion rate dissolved polysulfide and nucleation/growth of short-chain Li2S/Li2S2 has been built along with largely reduced contamination on the lithium anode side. Accordingly, good cyclability, high reversible capacity and Coulombic efficiency are achieved in Li-S cell with controlled S/E ratio without any additive. Other factors such as sulfur content in the composite and sulfur loading on the electrode also need careful concern in Li-S system in order to generate reproducible results and gauge the various methods used to improve Li-S battery technology.
Power control for successive interference cancellation with imperfect cancellation

This paper proposes and analyzes an iterative power control scheme for use with successive interference cancellation (SIC) in the presence of cancellation errors. SIC is shown by Andrews and Meng (see IEEE Transactions On Wireless Communications, Oct. 2001), to increase the capacity of cellular CDMA systems significantly, even if the signal cancellation is imperfect due to estimation errors. However, an important complication of SIC relative to conventional CDMA receivers is that a specific non-uniform distribution of powers must be assigned to the users in order for the system to function robustly. This paper proposes a simple up/down distributed iterative power control scheme for DS-CDMA systems employing SIC. We analyze its feasibility region and prove that it converges to close to the optimum solution even in the presence of estimation errors. The total received power is shown to be a reliable metric for admission control. This analysis considers both multi-rate CDMA where each user has a different target signal-to-interference-and-noise ratio (SINR), and asynchronous power control where user power updates occur asynchronously.
H2A.Z Functions To Regulate Progression through the Cell Cycle

Histone H2A variants are highly conserved proteins found ubiquitously in nature and thought to perform specialized functions in the cell. Studies in yeast on the histone H2A variant H2A.Z have shown a role for this protein in transcription as well as chromosome segregation. Our studies have focused on understanding the role of H2A.Z during cell cycle progression. We found that htz1Δ cells were delayed in DNA replication and progression through the cell cycle. Furthermore, cells lacking H2A.Z required the S-phase checkpoint pathway for survival. We also found that H2A.Z localized to the promoters of cyclin genes, and cells lacking H2A.Z were delayed in the induction of these cyclin genes. Several different models are proposed to explain these observations.
Generalized sampling expansion on lattices

The Papoulis Generalized Sampling Expansion (GSE) can be combined with Petersen-Middleton lattice sampling to obtain a GSE for n-dimensional bandlimited functions. Such expansions will be discussed for nonperiodic/periodic hybrids. The periodic and nonperiodic cases are incorporated as special cases. For a restrictive special case, a Parseval-like formula is proved for n-dimensional bandlimited functions sampled on periodic, nonuniform sample sets.
The Underuse of Screening Services Among Elderly Women with Diabetes

OBJECTIVE—To determine whether the use of nondiabetes-related preventive services (mammography, colorectal cancer screening, and bone density testing) among elderly diabetic women is different from the use among nondiabetic women. RESEARCH DESIGN AND METHODS—Using a representative sample of the U.S. elderly female population and the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare files, we identified women with or without diabetes who were ≥67 years of age on 1 January 1999. All women with a prior history of cancer were excluded. Bivariate and multivariate analyses were used to compare the rates of preventive service use and to understand the factors influencing their use in the next 2–4 years. RESULTS—Women with diabetes were less likely to have a mammogram (odds ratio [OR] 0.83 [95% CI 0.78–0.88]), colorectal cancer screening (0.79 [0.70–0.88]), and bone density testing (0.63 [0.58–0.69]). Women with diabetes seen by endocrinologists had significantly higher rates of bone density testing than women seen by primary care physicians. Women seen by obstetrician/gynecologists had the highest rates of use of all three services. CONCLUSIONS—Elderly women with diabetes are less likely to receive cancer and osteoporosis screening than women without diabetes. Physicians treating these patients need to assure that they receive all recommended preventive services appropriate for their age. Additional national guidelines, practice-based improvements, and patient education targeting those at greatest risk of not receiving these services may be needed to achieve parity.
Simulations Exploring the Dependence of Cloud-Cover Frequency Distribution on Cloud Size and Image Pixel Resolution

Abstract The dependence of pixel-scale cloud-cover frequency distribution on cloud size and pixel size is examined through Monte Carlo simulations. A shape parameter, which describes the shape of the frequency distribution, is found to be a simple function of the ratio of cloud size to pixel size. The form of the frequency distribution changes from U shape to bell shape when the ratio decreases. It becomes uniform when the ratio is about 0.8–0.9 for the cases where the regional-scale cloud cover is 0.5. It is shown that on average the cloud cover in partially cloudy pixels increases with increasing regional-scale cloud cover when the ratio of cloud size to pixel size is small. It becomes insensitive to regional-scale cloud cover when the ratio becomes large. It is also shown that, in comparison with the results from Monte Carlo simulations, the grid-scale cloud-cover frequency distribution obtained using a threshold method tends to be more U shaped, and that obtained using a method that assigns 50% cloudi...
The Evolution of a Toxic Enzyme in Sicariid Spiders

Sicariid spiders, including Loxosceles and Sicarius, have an unusual venom toxin with sphingomyelinase D activity. This toxin is a sufficient causative agent for the formation of dermonecrotic lesions when sicariid spiders, including the brown recluse, bite people. It also serves as a potent insecticidal neurotoxin, rapidly and irreversibly immobilizing prey. Sphingomyelinase D appears to represent a distinct evolutionary recruitment event of a novel venom toxin in spiders. After recruitment from a protein family serving a different (and unknown) role in spider’s body, the gene family (SicTox) has undergone substantial duplications and bursts of evolution under positive selection. Analyses are ongoing to understand the full breadth of functional specificity in this gene lineage and the full set of toxins in sicariid venoms.
Stanley v. Illinois' Untold Story

Stanley v. Illinois is one of the Supreme Court’s more curious landmark cases. The holding is well known: the Due Process Clause prohibits the state from removing children from unwed fathers simply because they are not married and requires the state to provide all parents with a hearing on their fitness. By recognizing strong due process protections for parents’ rights, Stanley reaffirmed Lochner-era cases that had been in doubt, and formed the foundation of modern constitutional family law. But Peter Stanley never raised due process arguments, so it has long been unclear how the Court reached this decision.This Article tells Stanley’s untold story for the first time, using original research of state court and Supreme Court records. Those records show that the state was concerned about Stanley’s parental fitness, and did not remove his children simply because he was unmarried, as is frequently assumed. But the state refused to prove Stanley unfit and relied instead on his marital status to justify depriving him of custody. That choice, and Stanley’s avoidance of a due process argument, created a complicated Supreme Court decision-making environment. This Article explores the Supreme Court’s decision-making in Stanley, and reveals new insights both about Stanley and the Court more broadly. Four justices changed their votes from conference to the final decision – an extreme amount of voting fluidity that shifted the case outcome. The justices’ varying and evolving views eventually led them to a strong due process holding, even though Stanley did not ask for one. This issue fluidity – when the Court issues a ruling based on arguments not raised by the parties – reflects a complex interaction between justices’ efforts to form a majority coalition and lawyers’ litigation choices. Finally, the justices’ papers reveal how Justice Harry Blackmun’s shift to the liberal wing of the Court – and to a staunch parents’ rights vote – began with his angst over Stanley, despite his vote for the state.
Liquidity in the Over-the-Counter Market for Corporate Bonds

Trading activity varies widely across individual corporate bond issues. Thirty-five percent of bonds do not change hands at all in the course of an average month, while some bonds see multiple transactions every trading day. This paper utilizes newly available transaction data to examine the factors associated with corporate bond liquidity and demonstrates that trading activity depends upon the relative visibility of the bond issue, the degree to which investor opinions regarding company value differ, and the likelihood of private information regarding the bond issue existing in the market.
Coffins versus cradles: Russian population, foreign policy, and power transition theory:

In May 2006, President Vladimir Putin said that Russia’s dire demographics were the biggest challenge facing Russia. We know little about how states conduct foreign policy under demographic decline...