cssi/SciSciGPT-SciSciNet huggingface dataset:
Basic biological research at the dawn of a new century.

opportunity to speak with you, particularly because this ceremony marks the successful completion of the studies you have undertaken. So first, I want to congratulate you for an achievement you can be very proud of and second, since you are now professional, I mean, card-carrying chemists and biochemists, I want to tell you a few things about the fields you have selected and discuss a couple of very serious and controversial problems that will confront us in the years to come, and that will not be solved without the contribution and help of people with your background and formation. I believe it is the right time to bring up these issues because the advances that have occurred in those areas in the last 10 or 20 years are absolutely without precedent. If the first half of the century that just ended was that of nuclear physics, with Einstein’s relativity and Max Planks’ quantum theory, atomic energy etc., there is no doubt that the second half belonged to biology. It gave us incredibly sophisticated new instrumentation and technologies, such as genetic engineering with gene cloning, manipulation, and expression without which we would know essentially nothing about our genetic make-up, hereditary diseases such as muscular dystrophy or diabetes, viral diseases such as AIDS, or cancer. And with the pervasive presence of the computer that allows us to analyze and display data, store them and retrieve them at the touch of a button, the scientists of today have at their disposal an incredible array of techniques undreamed of just a few years ago. The first problem I want to mention is world hunger. Indeed nowadays, more than 3/4 of a billion people remain chronically undernourished and over 180 million children are on the verge of starvation. But the agricultural environment has already been taxed to its limit and there are few realistic opportunities for opening up new land. Soils are eroding and losing their fertility, precious water supplies are being squandered, fish stocks are declining worldwide and have already been depleted in many parts of the world oceans, and forests have been devastated by the push of urbanization, by wars, fires, acid rain, toxic wastes, etc. Therefore, this new century will have to rely on biologists to feed a population that will exceed 8 and a half billion in 20 years. The task will be enormous because today, world population is increasing faster than agricultural productivity. So, unless one can curb overpopulation world-wide (and I don’t mean in developed countries only, but globally: after all, the
Gravitational collapse with a cosmological constant

We give a simple example of a spacetime in which one region undergoes gravitational collapse while another undergoes inflation. The spacetime is a spherical ball of dust in a region with a cosmological constant. The implications of this example for the “cosmic no hair” conjecture are discussed.
Structural damping caused by micro-slip along frictional interfaces

Abstract Damping in built-up structures is often caused by energy dissipation due to micro-slip along frictional interfaces (e.g., at bolted joints), which provides a beneficial damping mechanism and plays an important role in the vibration behavior of such structures. A careful study of the micro-slip phenomenon has been carried out using the finite element method. Two classical joint configurations, the press-fit joint and the lap-shear joint, have been used as the model problems. The focus of this paper is to evaluate the effect of dry friction on the damping response of frictional joint interfaces, to understand the evolution of the slip and stick regions along a joint interface during loading, and to quantify the amount of energy dissipation during cyclic loading and its dependence on structural and loading parameters. Finite element predictions are found to compare well with experimental measurements and are used to examine the validity and limitations of early analytical treatments in the literature.
The Routine Activities of Maritime Piracy

Maritime piracy has been romanticized extensively by writers and film-makers, but has otherwise been consigned to the past. Over the last five years, however, there has been a phenomenal increase in the number of attacks on commercial seafarers and their vessels. Modern-day piracy is frequently a violent and ruthless practice, and it inspires considerable fear among the ship-owners and crew members who are responsible for carrying their cargo into the territorial waters of other nations. This paper introduces the subject of modern-day maritime piracy, reviews theoretical explanations of this emerging crime control problem, then attempts to explain the recent spate of piratical attacks by invoking a routine activities approach.
Norfluoxetine Induces Spawning and Parturition in Estuarine and Freshwater Bivalves

Fluoxetine, a commonly prescribed antidepressant (Prozac), has been detected in sewage effluent. Its active metabolite norfluoxetine is more potent and has been detected in sewage influent and in fish tissues. We tested the effects of norfluoxetine on spawning and parturition in bivalves. Norfluoxetine induced significant spawning in zebra mussels and dark false mussels at concentrations as low as 5 μM. Norfluoxetine induced significant parturition in fingernail clams at 10 μM. Fluoxetine also induced spawning in dark false mussels at concentrations as low as 100 nM. Implications for environmental impacts of norfluoxetine and fluoxetine on native and exotic bivalves are discussed.
Possible role of Lewis acid catalysis in the oxidation of alkenes and α,β-unsaturated ketones using bleomycin-zn(ii) and bleomycin-fe(iii)-iodosylbenzene in aqueous methanol

Abstract C6H5IO in CH3OH-H20 is activated towards electrophilic attack upon various alkenes by Fe(ClO4).9H2O, FE(III) bleomycin and ZN(II) bleomycin. The results imply that direct transfer of oxygen from an Fe(V)=0 intermediate is not required in the mechanism of oxygenation by iron-containing species, and that much earlier work is questionable as models for biological oxygenation.
Comparisons of dose-dependent effects of systemic morphine on flexion reflex components and operant avoidance responses of awake non-human primates

Abstract Electromyographic activity and the force of reflex and operant responses were recorded following administration of morphine. Low doses facilitated reflex responses to input from A-δ afferents but not from A-β input. Higher doses inhibited A-δ responses but not A-β responses. Operant avoidance responses to visual cues were unchanged. Thus, depending on the dose, nociceptive reflexes were facilitated or inhibited, without associated effects on non-nociceptive input or on motor output.
What It's Really Like: The Complex Role of Medical Students in End-of-Life Care

Background: Medical student end-of-life care training provides insight into the hidden curriculum and physician professional development. Description: Second-year medical students at a university medical center listen to a panel discussion of 4th-year students and residents describing their end-of-life care experiences during clerkships. This discussion is intended to provide “anticipatory guidance” to 2nd-year students about challenging situations they might encounter on the wards. The purpose of this study was to analyze the content of the panel discussions by 4th-year students and residents to better understand their views of the end-of-life care curriculum. Evaluation: We performed a qualitative content analysis of transcripts from 2 years of panel discussions. Participants' comments focused primarily on the complexity of the role of medical students in end-of-life care. Three major themes emerged in the sessions: defining professional identity, conflicting expectations, and limited medical experience...
Spatial memory retention is enhanced by acute and continuous estradiol replacement.

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-μg 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.
Acetylcholinesterase inhibition by the ketone transition state analogs phenoxyacetone and 1-halo-3-phenoxy-2-propanones

Abstract 1-Phenoxy-2-propanone, 1-chloro-3-phenoxy-2-propanone, and 1-fluoro-3-phenoxy-2-propanone are competitive acetylcholinesterase inhibitors with K I values of 30, 0.85, and 2.2 μM, respectively, compared to 2 mM for 4-phenyl-2-butanone. The substituent effect on inhibition suggests that these compounds bind by formation of a tetrahedral adduct and are transition state analogs. Other evidence supports this conclusion: N-benzyl-2-chloroacetamide and 1-phenoxy-2-propanol are poor inhibitors (K I = 11 and >10 mM); 1-phenoxy-2-propanone and 1-chloro-3-phenoxy-2-propanone have K I values 330 and 140 times smaller than K m for corresponding substrates; and 1-chloro-3-phenoxy-2-propanone protects the enzyme against irreversible inhibition by CH 3 SO 2 F.
Neurobehavioral responses of neonatal rats to previously experienced odors of different concentrations.

Abstract Neonatal rats acquire an olfactory preference following daily exposure to an odor that is accompanied by tactile stimulation. In the present study, we determined the neurobehavioral responses of pups trained and tested with odors of either the same or different concentration. On postnatal day (PND) 1–18, all animals were exposed for 10 min/day to either peppermint or air while receiving perineal tactile stimulation. On PND 19, pups trained with a low odor concentration preferred that concentration to either air or a high odor concentration. However, rat pups trained with the high odor concentration preferred that odor to air, regardless of its concentration and showed equal preference between odor concentrations. These results suggest both that pups can learn to prefer a specific odor concentration and that they can learn to recognize odor quality across concentrations. To determine the neural responses to such stimuli, trained and control pups were exposed to either low or high peppermint odor concentrations following an injection of 14 C-labelled 2-deoxyglucose (2-DG). Early experience with the high odor concentration resulted in the 2-DG uptake response to both test odor concentrations which was higher than that of pups that had previous experience with either the low odor concentration or with clean air. Though the 2-DG density did not increase with test odor concentration, the size of the 2-DG foci did, regardless of previous experience. The 2-DG response to odor concentration is, therefore, influenced by both previous experience and immediate odor stimulus characteristics that are revealed in parallel responses within the olfactory bulb.
Alcohol use among american college students in relation to need for cognition and expectations of alcohol's effects on cognition

This article describes the development of a new self-report measure for assessing expectations for alcohol's cognitive effects and presents an empirical investigation of the association between cognitive alcohol expectancies and alcohol use. The present study also examined the potential moderating effects of need for cognition on the association between cognitive expectancies and drinking. Participants consisted of 179 college undergraduates from a midsized public university in the southeastern United States. Results of hierarchical multiple regression analyses, conducted separately for males and females, indicated several main effects for both cognitive alcohol expectancies and need for cognition on alcohol use. In contrast to these main effects, there were no significant multiplicative interaction effects, suggesting that need for cognition did not moderate the direction of association between cognitive expectancies and drinking. The results of homologizer/moderator analyses, however, did indicate a number of significant interaction effects for both males and females. These significant homologizer findings indicated that thestrength of association between cognitive alcohol expectancies and drinking increased as need for cognition increased. Implications of the present findings for future research are discussed.
Structure-based interpretation of missense mutations in Y-family DNA polymerases and their implications for polymerase function and lesion bypass.

Abstract Our understanding of the molecular mechanisms of error-prone lesion bypass has changed dramatically in the past few years. The concept that the key participants in the mutagenic process were accessory proteins that somehow modified the ability of the cell’s main replicase to facilitate bypass of normally blocking lesions has been replaced with one in which the replicase is displaced by a polymerase specialized in lesion bypass. The participants in this process remain the same, only their function has been reassigned. What was once known as the UmuC/DinB/Rev1/Rad30 superfamily of mutagenesis proteins, is now known as the Y-family of DNA polymerases. Quite remarkably, within the space of 3 years, the field has advanced from the initial discovery of intrinsic polymerase function, to the determination of the tertiary structures of several Y-family DNA polymerases. A key to determining the biochemical properties of each DNA polymerase is through structure–function studies that result in the site-specific substitution of particular amino acids at critical sites within each DNA polymerase. However, we should not forget the power of genetic selection that allows us to identify residues within each polymerase that are generated by “random mutagenesis” and which are important for both a gain or loss of function in vivo. In this review, we discuss the structural ramifications of several missense mutations previously identified in various Y-family DNA polymerase and speculate on how each amino acid substitution might modify the enzymatic activity of the respective polymerase or possibly perturb protein–protein interactions necessary for efficient translesion replication in vivo.
The Annealing Behavior of cryoECAP Processed Pure Aluminum under High Magnetic Field

The property and microstructure of pure Al prepared by the cryogenic ECAP after annealing at different temperatures and times with and without the application of 12T high magnetic field were investigated by hardness test and optical microscopy observation. The results show that with the application of high magnetic field, the hardness of cryo-ECAPed pure Al is lower than that of material annealing without high magnetic field. The high magnetic field accelerates crystallization of cryo-ECAPed pure Al during annealing.
Safety and efficacy of AS-1 red blood cell use in neonates.

Abstract Many Regional Blood Centers are providing AS-1(Adsol preservative) red blood cells (RBCs) as a standard product because of the extended shelf life (42 days). The use of AS-1 RBCs is concerning in neonates because of high exposure to dextrose, adenine and mannitol. We conducted this study to evaluate the safety and efficacy of AS-1 RBC use in neonates. We assigned one unit of AS-1 RBCs to each infant for small volume transfusions (15 ml/kg) for the life of the unit (42 days). The study was conducted for one year. The infants under 1500 g were included in the study. We measured the pre- and post-transfusion hematocrit, post-transfusion serum sodium, potassium, glucose, bilirubin and blood pH. We compared the average number of transfusions per patient and average blood donor exposure per patient using AS-1 RBC to CPDA-1 packed red blood cells (PRBC) use, data available for prior year. We monitored the blood transfusion reactions during the study period. The hematocrit increased significantly from 30.1±4.6 pre-transfusion to 38.3±4.9 post-transfusion. The post-transfusion serum bilirubin, blood pH, serum potassium, sodium and glucose remained within the normal range. In spite of an increase in the number of average transfusions per patient with AS-1 RBC (6.67±5.1), the average donor exposure (1.8±1.1) remained less than two donors. There were not any transfusion reactions reported during the study. In conclusion, the use of AS-1 red blood cells is safe for small volume transfusions in neonates.
Lanthanide inhibition of calcium binding by muscle microsomes: ATP and time dependency.

Abstract Lanthanum ions exert a potent inhibition on the binding of calcium ions by muscle microsomes, and a lesser effect on the associated Ca-stimulated ATPase. Ca binding inhibition may occur at La concentration as low as 5μ m , while ATPase inhibition requires 100 to 200 μ m . Previous studies have either found no effect of La, or relatively minor inhibition of Ca binding only at higher La concentration. The present work shows that the effect of La is related not only to simple La binding to membranes, but also to a slow augmentation by Mg ATP of binding of the lanthanide to the membrane. This results in a parallel time-dependent decreased inhibition of Ca binding. ATP also diminishes the La inhibition when ATP concentration is greater than 10 −4 by its chelating effect on the lanthanide, reducing the effective La concentration. Under given conditions, therefore, no La inhibitory effect may be seen. The data explain previous inconsistencies in the literature on La effect on muscle microsomes.
The India Way: Lessons for the U.S.

Executive Overview We describe a distinctive approach to business associated with the major corporations in India and contrast it with practices in the United States. Specifically, the Indian approach eschews the explicit pursuit of shareholder value in favor of goals associated with a social mission. These companies make extraordinary investments in their employees and empower them in decision making. These practices combine with a distinctively Indian approach to problem solving to create a competitive advantage that has led to spectacular business growth, not just within India but in international markets as well. A particularly important lesson for the United States is that the major Indian companies are not succeeding despite the fact that they are pursuing a social mission and investing in their employees. They are succeeding precisely because they do so.
Tolerability of and adherence to combination oral therapy with gefitinib and capecitabine in metastatic breast cancer.

Purpose: This phase I study explored gefitinib (G) and capecitabine (C) in metastatic breast cancer (MBC). Methods: Sequential cohorts (n = 3) received G and escalating C on a 14 day on/7 day off schedule, with a validation cohort (n = 10) at the maximum tolerated dose (MTD). Dose limiting toxicity (DLT) was defined in cycle 1. The primary endpoint was safety; secondary endpoints included response and adherence. Results: About 19 patients were treated for a median of 5 cycles. No patients in sequential cohorts experienced DLT; C MTD was 2,000 mg/m2/day when paired with daily G 250 mg. In the validation cohort, four experienced serious toxicities, including diarrhea, mucositis, and palmarplantar dysesthesia. At the MTD, 6 (46%) required a C dose reduction, and 3 (23%) came off study for toxicity. One partial response was observed (8%, 95% CI 0.2–38.5%); five had stable disease >24 weeks (26, 95% CI 9–51%). Patients missed few drug doses, with the suggestion of overadherence to therapy. Conclusions: In this phase I study of G and C in MBC, a C MTD was identified, and significant toxicity was observed. About 8% demonstrated a response, with 26% maintaining stable disease. The possibility of overadherence, as suggested in this study, may have implications for other trials of oral antineoplastic therapy.
Antibody Response to a Polyvalent Pseudomonas Vaccine in Children with Leukemia

Pseudomonas aeruginosa infection accounts for 30% of gram-negative bacteremias in children with acute leukemia at Memorial Hospital. There is a mortality rate of 87% despite antimicrobial therapy. Previous studies in animals and man following severe burns suggest that P. aeruginosa infection may be subjected to immunological control. Active immunization of 20 leukemic children in bone marrow remission was attempted with a lipopolysaccharide antigen derived from 7 strains of P. aeruginosa (Fisher-Devlin immunotypes). Vaccination consisted of 4 intramuscular injections at weekly intervals. Febrile and local reactions occurred in all, but were not severe enough to discontinue the procedure. The appearance of antibody was demonstrated by 1 to 5 preipitin bands using the Oucterlony immunodiffusion technique. This was correlated with a rise in hemagglutinating antibody titers. Sixteen children demonstrated antibody response within one month, despite the immunosupressive antileukemic therapy that they were receiving. If this antibody proves to be protective against P. aeruginosa infection by further control studies in progress, vaccination of patients early in the course of leukemia would be indicated.
The Role of Goal Orientation in Emerging Adult Identity Processing Styles

Universities are considered to be settings for students to develop and transform themselves during emerging adulthood. A total of 1,236 university students (774 women, 462 men; M age = 21.54 years, SD age = 5.23 years) participated in a study examining the relation between students' identity processing style and goal orientation. Results indicated that an information-oriented identity style was associated with a mastery goal orientation, whereas a normative-oriented identity processing style was predictive of a greater concern with performance goals. The diffusion/avoidant identity style was not strongly related to any goal orientation. In addition, results showed that students in their junior or senior year in school (independent of social desirability tendencies) were more often classified as information oriented in their identity style compared with students in their freshman or sophomore year in school.
Fabrication of Extremely Lightweight Mirrors

Further progress in astronomy requires large.(approx. 10m class) space telescopes in all wavelength bands, from IR to X-rays. The enabling of this progress requires optical fabrication technologies that not only can make mirrors that are orders of magnitude less massive than the present ones, but also orders of magnitude less expensive. In the past five years, we have been developing lightweight X-ray mirrors to meet mission requirements of the Constellation-X, which is NASA s next major X-ray observatory scheduled for launch some time in the next decade. In this talk, I will describe in detail a glass forming, or slumping, technique that allows a high-fidelity copying of a mandrel s figure while preserving the microroughness of the float glass surface. In particular, I will address the possibility of applying this technique to making extremely large optical telescopes.
Differences in smoking cessation strategies between men and women

Abstract This descriptive research was designed to identify differences in smoking cessation strategies between men and women in a cross-sectional population sample of current smokers in the upper Midwest. Data on the number of previous quit attempts, the success and persistence in quit attempts, future intensions to change smoking habits, and strategies planned for cessation were obtained from 1669 smokers. Log-linear analyses controlling for age and the number of cigarettes smoked revealed significant gender differences. Men and women appear to approach smoking cessation differently. Women were more tentative and less committed to quitting smoking entirely. Women were also less successful in sustaining smoking cessation attempts for longer than one week. Efficacy expectations and differential attributions for failure were suggested as possible explanations for the results, however further research will be necessary to confirm or disconfirm these hypotheses.
Development of the zone method for linearly-anisotropic scattering media

Abstract The purpose of this study is to extend the zone method to gray, absorping, emitting and linearly-anisotropic scattering media enclosed in an infinite plane layer. The medium is assumed to be homogeneous and has a refractive index of unity. The boundary surfaces are gray, diffusely emitting and reflecting, and opaque with constant temperature. The governing radiative transport equation is solved. The resulting integral expressions are discretized under the assumption of uniform temperature within each zone. The divergence of the radiative flux and net wall radiation terms are expressed in terms of total exchange areas (TEA). Expressions for special cases are presented and the results are compared with those of a previous study. The properties of TEA are also studied, and the results are summarized. The zone method is applied to radiative equilibrium and to heat transfer by combined conduction and radiation. Good agreement with results from other methods indicates the accuracy of the zone method as well as its compatibility with other modes of heat transfer. Based on the formulation, the same approach may be applied to develop zone method expressions for multi-dimensional problems.
Energetics of the formation and migration of defects in Pb(110).

As part of our investigations on the disordering of metal surfaces, we report the results of our calculations of the energetics of formation and migration of defects in Pb(110) using molecular-dynamics and molecular-statics simulations. We used the embedded-atom method to describe the interatomic interactions. Defect formation and migration energies have been calculated at the surface as well as in the near-surface region. Vacancy, divacancy, and interstitial formation and migration energies converge to bulk values already at a few layers below the surface. Our results are compared with recent simulations of Cu and Ni and with experimental data. We also calculated the surface Debye temperature and surface energy. We find that the surface Debye temperature, surface single-vacancy formation energy, and surface divacancy formation energy are all lower than their bulk values. Our result for the surface energy is lower than the experimental values.
3D Hand Tracking and Motion Analysis with a Combination Approach of Statistical and Syntactic Analysis

This paper describes a new approach to solve the problem of real-time 3D hand tracking and motion analysis with a combination approach of statistical and syntactic analysis. The fundamental idea is to divide the problem into two levels according to the hierarchical property of hand gestures. The lower level of the approach implements posture detection and tracking with a statistical method based on Haar-like features and the AdaBoost learning algorithm. With this method, a group of hand postures can be detected and tracked in 3D mode in real-time. The robustness against cluttered backgrounds is achieved by background subtraction and smoothing. The higher level of the approach implements hand motion analysis using the syntactic analysis based on stochastic context-free grammars. Two structured gestures are analyzed in our experiment. Given an input string, based on the stochastic parsing, the corresponding structured gesture can be identified by looking for the SCFG that has the higher probability to generate the input string.
Evaluation of the Plot Method for Identifying Potentially Biased Test Items.

The notion that some items in a test may be biased against specific minority groups has become a matter of substantial concern for both test users and test developers. Numerous approaches for the study of item bias, based upon standard testing technology and item response theory, have been advanced and researched in recent years (e.g. Berk, 1982; Hoover and Kilen, 1984; Ironson and Subkoviak, 1979; Shepard, 1981; Shepard, Camilli and Averill, 1981; Shepard, Camilli and Williams, 1984).
KrF excimer laser micromachining of MEMS materials: characterization and applications

Conventional photolithography-based microfabrication techniques are widely used to create microscale structures and devices nowadays. However, these techniques are limited to two-dimensional fabrication and also to particular materials. Excimer laser micromachining enables us to overcome those limitations and facilitates three-dimensional (3D) microfabrication. This paper presents a comprehensive characterization study for excimer laser micromachining of micro-electro-mechanical system (MEMS) materials. By using a 248 nm KrF excimer laser and four representative MEMS materials (Si, soda-lime glass, SU-8 photoresist and poly-dimethysiloxane (PDMS)), the relations between laser ablation parameters (fluence, frequency and number of laser pulses) and etch performance such as the etch rates in the vertical and lateral directions, aspect ratio, and surface quality were obtained. The etch rate increased almost linearly for all four materials as the fluence increased but no significant variation in etch rate was observed as the frequency of laser pulses was changed. The etch rate was also inversely proportional to the number of laser pulses. Physical deformation in the laser-machined sites on PDMS and SU-8 was investigated using SEM imaging. In order to demonstrate the 3D microfabrication capability of an excimer laser and the utility of this characterization study, two novel implantable biomedical microscale devices made of SU-8 and PDMS were successfully fabricated using the optimized laser ablation parameters obtained in this study.
Shrinkage estimators for covariance matrices.

Estimation of covariance matrices in small samples has been studied by many authors. Standard estimators, like the unstructured maximum likelihood estimator (ML) or restricted maximum likelihood (REML) estimator, can be very unstable with the smallest estimated eigenvalues being too small and the largest too big. A standard approach to more stably estimating the matrix in small samples is to compute the ML or REML estimator under some simple structure that involves estimation of fewer parameters, such as compound symmetry or independence. However, these estimators will not be consistent unless the hypothesized structure is correct. If interest focuses on estimation of regression coefficients with correlated (or longitudinal) data, a sandwich estimator of the covariance matrix may be used to provide standard errors for the estimated coefficients that are robust in the sense that they remain consistent under misspecification of the covariance structure. With large matrices, however, the inefficiency of the sandwich estimator becomes worrisome. We consider here two general shrinkage approaches to estimating the covariance matrix and regression coefficients. The first involves shrinking the eigenvalues of the unstructured ML or REML estimator. The second involves shrinking an unstructured estimator toward a structured estimator. For both cases, the data determine the amount of shrinkage. These estimators are consistent and give consistent and asymptotically efficient estimates for regression coefficients. Simulations show the improved operating characteristics of the shrinkage estimators of the covariance matrix and the regression coefficients in finite samples. The final estimator chosen includes a combination of both shrinkage approaches, i.e., shrinking the eigenvalues and then shrinking toward structure. We illustrate our approach on a sleep EEG study that requires estimation of a 24 x 24 covariance matrix and for which inferences on mean parameters critically depend on the covariance estimator chosen. We recommend making inference using a particular shrinkage estimator that provides a reasonable compromise between structured and unstructured estimators.
The Antimatter Photon Drive, A Relativistic Propulsion System

This paper describes a propulsion system that derives its thrust from electron-positron annihilation. It also describes how a spacecraft equipped with this engine can be used to launch manned missions to Mars and Jupiter in as little as 3.8 and 10.8 days respectively. Technical problems associated with the antimatter engine and potential solutions are also discussed. Throughout this paper, this engine is referred to as the Antimatter Photon Drive or (APD).
The theoretical relationship between foliage temperature and canopy resistance in sparse crops

One-dimensional, sparse-crop interaction theory is reformulated to allow calculation of the canopy resistance from measurements of foliage temperature. A submodel is introduced to describe eddy diffusion within the canopy which provides a simple, empirical simulation of the reported behavior obtained from a second-order closure model. The sensitivity of the calculated canopy resistance to the parameters and formulas assumed in the model is investigated. The calculation is shown to exhibit a significant but acceptable sensitivity to extreme changes in canopy aerodynamics, and to changes in the surface resistance of the substrate beneath the canopy at high and intermediate values of leaf area index. In very sparse crops changes in the surface resistance of the substrate are shown to contaminate the calculated canopy resistance, tending to amplify the apparent response to changes in water availability. The theory is developed to allow the use of a measurement of substrate temperature as an option to mitigate this contamination.
Shocks and PDRS

Shock waves, generated in various environments by supersonic motions, are common in interstellar space. The mechanical compression and heating caused by shocks produce distinctive signatures. Similar signatures are generated also by the radiative heating effect of hard UV photons in photodissociation regions. This review covers some of the outstanding properties of both phenomena, which play important roles in controlling the structure of interstellar regions and the process of star formation.
On the investigation of 1/F noise of polysilicon emitter P-N-P transistors in a C-BiCMOS technology

Via forward current stress and reverse breakdown stress to intentionally change the interfacial layer properties, the 1/f noise of base current in polysilicon emitter p-n-p transistors in a C-BiCMOS technology has been investigated. The results show that the 1/f noise of base current is proportional to I/sub b//sup 2/, and the 1/f noise from majority carrier transport through polysilicon grain boundaries is a primary source of 1/f noise. >
HABITAT MODIFICATION AND REFUGE FROM SUBLETHAL STRESS DRIVE A MARINE PLANT–HERBIVORE ASSOCIATION

Canopy-forming plants and algae, in addition to their role as food, can positively affect higher trophic levels by providing protection from predation or stressful abiotic conditions. In the low rocky intertidal zone of the Pacific Northwest, the chiton Katharina tunicata is closely associated with the canopy-forming alga Hedophyllum sessile. In a 27-month field experiment, I used experimental devices to mimic characteristics of the Hedophyllum canopy and monitored the abundance and physiology of Katharina to determine the mechanism behind this association. The data show that this association is due to selection of shaded microhabitats by Katharina, and that neither predation nor Hedophyllum per se influenced the distribution of the chiton. Exclusion of visual predators had no effect on chiton abundance, and tests of the effects of shade independent of Hedophyllum presence indicated that the shade produced by the alga was critical to the chiton. Seasonal fluctuations in levels of 70 kDa (1.16 × 10−19 g) heat shock proteins (Hsp70) indicate that Katharina experience sublethal physiological stress during the spring and summer. The corresponding use of shaded areas during spring and summer low tides suggests that the chiton's distribution is limited during these seasons by the availability of refugia from sublethal abiotic stresses. Subtle variations in environmental conditions are also important to this association; the strength of the positive interaction varied annually, becoming more positive in warm summers (1998 and 2000) and neutral in a cooler summer (1999). On a finer scale, physiological measurements indicate that the response of chitons to summertime temperatures depends on both absolute temperature change and the animal's recent thermal history. In particular, the seasonal onset of daytime low tides in the spring is associated with increased Hsp70 levels, indicating that this is a significant physiological event for Katharina. The importance of facultative positive interactions that allow consumers to escape from sublethal abiotic stresses will likely be variable in time but can have large impacts on communities both by affecting the small-scale distribution of consumers over the short term and potentially by affecting the persistence of organisms over the long term.
SIX1 acts synergistically with TBX18 in mediating ureteral smooth muscle formation

Dysfunction of the ureter often leads to urine flow impairment from the kidney to the bladder, causing dilation of the ureter and/or renal pelvis. Six1 is a crucial regulator of renal development: mutations in human SIX1 cause branchio-oto-renal (BOR) syndrome and Six1–/– mice exhibit renal agenesis, although the ureter is present. It remains unclear whether Six1 plays a role in regulating ureter morphogenesis. We demonstrate here that Six1 is differentially expressed during ureter morphogenesis. It was expressed in undifferentiated smooth muscle (SM) progenitors, but was downregulated in differentiating SM cells (SMCs) and had disappeared by E18.5. In Six1–/– mice, the ureteral mesenchymal precursors failed to condense and differentiate into normal SMCs and showed increased cell death, indicating that Six1 is required for the maintenance and normal differentiation of SM progenitors. A delay in SMC differentiation was observed in Six1–/– ureters. A lack of Six1 in the ureter led to hydroureter and hydronephrosis without anatomical obstruction when kidney formation was rescued in Six1–/– embryos by specifically expressing Six1 in the metanephric mesenchyme, but not the ureter, under control of the Eya1 promoter. We show that Six1 and Tbx18 genetically interact to synergistically regulate SMC development and ureter function and that their gene products form a complex in cultured cells and in the developing ureter. Two missense mutations in SIX1 from BOR patients reduced or abolished SIX1-TBX18 complex formation. These findings uncover an essential role for Six1 in establishing a functionally normal ureter and provide new insights into the molecular basis of urinary tract malformations in BOR patients.
What kind of intensification? Agricultural practice, soil fertility and socioeconomic differentiation in rural Burkina Faso

In rural Burkina Faso, intensification has been an uneven process that has resulted in social costs, particularly in the form of uneven distribution of assets and disparate environmental trade-offs. This study examines the effects of wealth status on agricultural practice and soil fertility, arguing that differences in the practices of wealthier and poorer farmers lead to differential social and environmental outcomes. Two concerns are highlighted. First is the role of poverty in environmental degradation. Much of the debate about the role of wealth and poverty in environmental outcomes in developing countries has pinpointed poverty as the main causal explanation. Using studies of agricultural practices and soil fertility from several villages in southwestern Burkina Faso, this paper will counter this dominant view by showing that wealthier farmers farm much larger areas, have fewer trees in their fields, and use higher levels of animal traction which, in turn, has led to lower levels of soil fertility. A second concern is that while poorer farmers may have agricultural practices that minimize environmental degradation, their exclusion from key institutions that provide access to resources has serious livelihood consequences and potentials for increasing socioeconomic differentiation. The agricultural practices of wealthier farmers, while not optimal environmentally, result in higher levels of household wealth. A paradox emerges that while poorer farmers are conserving environmental resources, they are doing so at the expense of economic development and well-being.
Thinking about American Workers in the 1920s

Labor historians' abiding interest in manifestations of working-class solidarity needs to be related at all times to analysis of the formation and reconstructions of bourgeois hegemony. All industrialized countries experienced declining strike activity and trade union membership between 1921 and 1933, although the patterns of subsidence and occasional revival of industrial confrontations were quite different in Germany or England from those evident in France or the United States. So stark was the contrast within the United States between the decade Irving Bernstein called "the lean years" and "the turbulent years" that followed, that historians have been prone to separate the twenties and thirties into two distinct periods for study. In this essay I wish to explore some of the more continuous lines of social and political developments between the world wars that deserve the attention of historians of the working class, to sug gest some international aspects of U.S. experience, and to identify topics that appear to be in special need of further research. Sidney Fine's perceptive account of the policies and beliefs to which the leading executives of the General Motors Corporation adhered when con fronted by rising union membership and eventual sit-down strikes in the thir ties clearly reveals a continuity of managerial powers, principles, and practices dating back at least to the post-World War I years. Management was to culti vate and defend "loyal employees"; a closed shop agreement with a union would decisively undermine that objective and consequently had to be avoided at all costs. Efficient production methods required not only systematic analysis and assignment of work tasks and foremen selected, trained and guided as the front line of management, but also planned use of wage incentives. Although executives of the company needed to maintain incessant com munication with both their employees and the local elites of the communities in which they were located, they were also determined to avoid any "outside" interference in their direction of the enterprise. The autonomy of the enter prise was the sanctum sanctorum of interwar management. As Ronald Schatz, Nelson Lichtenstein, Katherine Stone, Karl Klare, Christopher Tomlins, and Fine himself have argued?and as Sumner Slichter revealed in 1940?
The possibility of lateral structure inside the core and its implications for nutation and Earth tide observations

SUMMARY We show that there can be lateral structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography on the core-mantle or inner core-outer core boundaries. We describe a method for calculating the internal structure, given knowledge of the forcing. We discuss the possible effects of this structure on results for the core-mantle boundary topography inferred from observations of the Earth’s forced nutations and diurnal earth tides. We consider the possible implications of a thin, low-density fluid layer at the top of the core.
Effects of vitamin A deficiency on rat liver alcohol dehydrogenase expression and alcohol elimination rate in rats.

Background: Vitamin A has been suggested to regulate the expression of liver alcohol dehydrogenase (ADH) in humans. There are few studies on the ability of retinoic acid to affect ADH expression in vivo and none on its effects on alcohol metabolic rate. Methods: Male Sprague Dawley® rats were used for isolation of hepatocytes or were rendered vitamin A deficient by feeding a deficient diet for 7 weeks. ADH, retinoic acid receptor β, and retinoid X receptor α protein levels were analyzed by Western blotting. Alcohol elimination rate was determined by following blood alcohol levels after administering a 1.5 g/kg dose of ethanol intraperitoneally. Results: Retinoic acid had no effect on ADH protein in cultured hepatocytes. In the vitamin A deficient rats, retinol was not detectable in serum or liver at the time animals were killed. ADH and retinoid X receptor α protein levels were unchanged in the deficient group compared with a vitamin A sufficient control group, whereas retinoic acid receptor β levels increased 40%. The deficient rats had a reduced volume of distribution of alcohol, but this largely was accounted for by their smaller body size. The alcohol elimination rates were lower in the deficient animals, but this was accounted for by reduced body and liver weights. Conclusions: Severe vitamin A deficiency did not alter liver ADH protein expression or rates of alcohol elimination when expressed per gram of body or liver weight.
Tunable coherent optical transversal EDFA gain equalization

In this paper, we propose a fiber amplifier gain equalizer using a coherent optical transversal filter. The gain equalizer is tunable and has a bandwidth in the order of 30 nm. We also study the effects of different parameters such as input signal power pattern and the input pump power on the gain profile of the amplifier. The results show that, when the input signal power pattern changes, the amplifier does not maintain its gain profile. The gain profile has to be maintained in order to make the gain equalization effective. We show that, the pump input power can be adjusted so that the changes in the gain profile are compensated for. The gain profile varies quite slowly, hence compensation is feasible. As an example, we discuss the design of a gain equalizer for a system consisting of seven wavelength channels. >
Efficacy of chlorfenapyr against adult Tribolium castaneum exposed on concrete: effects of exposure interval, concentration and the presence of a food source after exposure.

Chlorfenapyr, an insecticidal pyrrole, was applied to concrete arenas at concentrations of 1.1, 0.825, 0.55, and 0.275 g of active ingredient [AI]/m2. Adult Tribolium castaneum (Herbst), the red flour beetle, were exposed for 2, 4, or 8 h at each concentration, then removed and held either with or without food (wheat flour) for 7 days. Survival was assessed when the beetles were removed from the exposure arenas and daily during the post-exposure period. In the presence of food, survival was high regardless of concentration and the day on which post-treatment survival was assessed, but survival did decrease as the exposure period increased from 4 to 8 h. When the beetles were not given food after exposure, survival at each concentration and exposure period declined during the 1-week post-exposure assessments. This pattern of decrease could be described by linear and non-linear equations. Results show the presence of food material greatly compromised effectiveness of the insecticide, and emphasize the importance of cleaning and sanitation in conjunction with insecticide treatments.