cssi/SciSciGPT-SciSciNet huggingface dataset:
H-enhanced mobility and defect formation at surfaces: H on Be(0001).

First-principles calculations of the interaction of H with the close-packed Be(0001) surface reveal that adsorbed H reduces barriers and formation energies for Be surface defects. A H atom adsorbed on top of a Be adatom reduces the Be atom{close_quote}s surface-diffusion barrier by a factor of 3. Preferential binding of H to surface defects reduces the formation energy of steps, adatoms, and vacancies on Be(0001). Because H adatoms repel each other on the flat surface, but not if adsorbed at the defects studied here, the formation of these defects is especially facile at high H coverage. These results explain the experimental findings that the H-induced vacancy reconstructions, which dominate the high H coverage regime, form at as low as 100 K. {copyright} {ital 1996 The American Physical Society.}
Aerobic Exercise and Bone Density at the Hip in Postmenopausal Women: A Meta-Analysis

Background. The effects of aerobic exercise on bone density at the hip in postmenopausal women in the absence of estrogen replacement therapy are not currently known. The purpose of this study was to examine the effects of aerobic exercise on bone density at the hip in postmenopausal women. Methods. Using the meta-analytic approach, studies dealing with the effects of aerobic exercise on bone density at the hip in postmenopausal women were searched for using computerized literature searches (MEDLINE, January 1978 to December 1995) as well as cross-referencing from retrieved review articles and original investigations. Results. A total of 18 effect sizes were derived from six studies. Using a fixed-effects model and bootstrap resampling (5,000 iterations) overall changes in bone density at the hip yielded an average effect size of 0.43 (95% CI = 0.04 to 0.81), equivalent to an overall change of approximately 2.42% (exercise = 2.13%; nonexercise = −0.29%). Statistically significant differences were observed when effect sizes were partitioned by country in which studies were conducted (United States,x= 1.03, 95% CI = 0.48 to 1.68; other countries,x= 0.18, 95% CI = −0.27 to 0.54;Qb= 5.44,P= 0.04) and calcium intake (≥1,000 mg/day,x= 0.83, 95% CI = 0.49 to 1.23; <1,000 mg/day = −0.23, 95% CI = −0.85 to 0.21;Qb= 10.64,P= 0.002). Conclusions. The overall results of this study suggest that site-specific aerobic exercise has a moderately positive effect on bone density at the hip in postmenopausal women. However, a need exists for additional, well-designed studies before a final recommendation can be made regarding the efficacy of aerobic exercise as a nonpharmacologic intervention for optimizing bone density at the hip in postmenopausal women.
A new calorimeter for temperatures above 1400 K

Abstract A new high temperature calorimeter, based on modifications and improvements to the commercial integrated heat flux Setaram design is described. In this unit thermal effects are measured differentially along the vertical axis of the calorimeter. Performance was tested at 1473 K through the measurement of the enthalpies of formation of intermetallic compounds, using high temperature mixing calorimetry.
Rubidium in Metal-deficient Disk and Halo Stars

We report the first extensive study of stellar Rb abundances. High-resolution spectra have been used to determine, or set upper limits on, the abundances of this heavy element and the associated elements Y, Zr, and Ba in 44 dwarfs and giants with metallicities spanning the range -2.0 < [Fe/H] < 0.0. In metal-deficient stars Rb is systematically overabundant relative to Fe; we find an average [Rb/Fe] of +0.21 for the 32 stars with [Fe/H] < -0.5 and measured Rb. This behavior contrasts with that of Y, Zr, and Ba, which, with the exception of three new CH stars (HD 23439A and B and BD +5°3640), are consistently slightly deficient relative to Fe in the same stars; excluding the three CH stars, we find that the stars with [Fe/H] < -0.5 have average [Y/Fe], [Zr/Fe], and [Ba/Fe] of -0.19 (24 stars), -0.12 (28 stars), and -0.06 (29 stars), respectively. The different behavior of Rb on the one hand and Y, Zr, and Ba on the other can be attributed in part to the fact that in the Sun and in these stars Rb has a large r-process component while Y, Zr, and Ba are mostly s-process elements with only small r-process components. In addition, the Rb s-process abundance is dependent on the neutron density at the s-processing site. Published observations of Rb in s-process enriched red giants indicate a higher neutron density in the metal-poor giants. These observations imply a higher s-process abundance for Rb in metal-poor stars. The calculated combination of the Rb r-process abundance, as estimated for the stellar Eu abundances, and the s-process abundance, as estimated for red giants, accounts satisfactorily for the observed run of [Rb/Fe] with [Fe/H].
ACCURATE DETERMINATION of TRANSPARENCY CURRENT in PACKAGED SEMICONDUCTOR LASERS and SEMICONDUCTOR OPTICAL AMPLIFIERS

The reliability of semiconductor laser diodes and related devices is a significant issue for their deployment in many applications [1, 2], creating demand for device diagnostics applicable to packaged devices. Measurements of the transparency current density (J0) in laser diodes and traveling-wave semiconductor optical amplifiers (SOAs) can provide such a diagnostic. It is essential, however, to measure J0 on packaged devices, so that they can be characterized after aging or degradation. This precludes techniques requiring data from multiple devices (e.g., an ensemble with different lengths). J0 is conventionally measured using a junction-voltage technique [3,4], in which an input optical signal induces a change in carrier density in the active region due to stimulated absorption or emission. The result is a voltage drop across the diode. At material transparency, the stimulated absorption is exactly balanced by the stimulated emission and the voltage drop goes to zero. Since the polarity of the voltage drop changes sign at current densities above J0, the optical input beam is typically modulated and lock-in amplification is employed to sensitively detect the polarity sign flip. Here we show that this technique is not reliable for certain types of laser structures, because the deduced J0 is strongly dependent on device packaging—that is, the measured Jo varies with the manner in which light is coupled into the diode waveguide. For packaged SOAs, we propose and demonstrate an alternative all-optical technique to overcome this problem. One important advantage of the optical method over the junction voltage method is that the actual device optically-guided mode is directly sampled. In the case of packaged semiconductor lasers, our all-optical method can complement the junction-voltage method to resolve device versus packaging degradation.
Nerve regeneration in C. elegans after femtosecond laser axotomy

We show sub-micron scale surgery with femtosecond lasers in a tiny living organism. By just cutting few nano-scale nerve connections inside the nematode C. elegans , we can stop the whole worm from moving backwards. This delicate axotomy keeps the surrounding of the severed axons un-damaged so that the axons can regrow back, and the worms recover and can move backwards again. These results demonstrate, for the first time, nerve regeneration in such a tiny organism, in its evolutionarily simplest form. The ability to perform precise sub-micron scale axotomy on such organisms provides tremendous research potential for rapid screening of drugs and discovery of new biomolecules affecting regeneration and development.
AN ACETAL DERIVATIVE OF ILLUDIN S WITH IMPROVED ANTITUMOR ACTIVITY

Abstract Methylene acetal of an epimer of illudin S ( 5 ) was obtained by treating illudin S with a large excess of paraformaldehyde in 1N H 2 SO 4 solution. X-ray crystallographic analysis showed that the configuration at the allylic carbon has been inverted. This acetal was found to be less toxic and showed a higher therapeutic index than illudin S.
AR-quiver approach to affine canonical basis elements

This is the continuation of [Y. Li, Affine quivers of type A˜n and canonical bases, math.QA/0501175]. We describe the affine canonical basis elements in the case when the affine quiver has arbitrary orientation. This generalizes the description in [G. Lusztig, Affine quivers and canonical bases, Publ. Math. Inst. Hautes Etudes Sci. 76 (1992) 111–163].
PRIMITIVE INDEPENDENCE RESULTS

We present some new set and class theoretic independence results from ZFC and NBGC that are particularly simple and close to the primitives of membership and equality (see Secs. 4 and 5). They are shown to be equivalent to familiar small large cardinal hypotheses. We modify these independendent statements in order to give an example of a sentence in set theory with 5 quantifiers which is independent of ZFC (see Sec. 6). It is known that all 3 quantifier sentences are decided in a weak fragment of ZF without power set (see [4]).
Highlights of Recent Results with Clas

Recent results on the study of the electromagnetic structure of nucleon resonances, the spin structure of protons and neutrons at small and intermediate photon virtuality, and the search for exotic pentaquark baryons are presented.
Sterically-Driven Anhydride Formation

Abstract Oxidative coupling of highly substituted carboxylic acid dianions affords hindered succinic acid derivatives which undergo facile intramolecular anhydride formation. A novel, but low yield, synthetic sequence converts 4′-methoxypropiophenone into diethylstilbestrol.
Do choice schools break the link between public schools and property values? Evidence from house prices in New York City

Abstract While school choice has attracted much attention from policymakers and researchers, virtually all of the research has focused on the relationship between school choice and student academic performance. There is, in contrast, little work examining whether additional choice schools weaken the link between residential property values and locally zoned schools — despite the well accepted theoretical (and empirical) link between schools and housing. As school choice becomes more important in reforming urban school systems, and improving public schools is critical for attracting and retaining middle class families in urban neighborhoods, it is important to understand how increasing school choice shapes the long-term economic health and viability of the country's central cities. In this paper, we examine how choice schools affect house prices, particularly the link between the quality of locally zoned schools and surrounding housing values. Our study utilizes rich data on New York City public elementary schools geo-coded and matched to data on property sales for a fifteen-year period beginning in 1988. To identify the impact of a choice school on the capitalization of school quality into housing values first we incorporate a boundary discontinuity approach to compare the capitalization of zoned school quality into housing prices of buildings that are close to one another but in different elementary school attendance zones. We rely on smaller and smaller distances from the boundary to test the stability of our results. Second, we compare housing units that are within 3000 ft of a choice school to housing units outside of these rings, which is traditionally considered the ‘walk zone’ around a school. Third, we take advantage of choice school openings to look at the capitalization rates before and after the choice school opens. We find that the proximity of alternative school choices does weaken the link between zoned schools and property values. The opening of a choice school reduces the capitalization of test scores from zoned schools into housing values by approximately one third.
Dynamics with choice

Dynamics with choice is a generalization of discrete-time dynamics where instead of the same evolution operator at every time step there is a choice of operators to transform the current state of the system. Many real-life processes studied in chemical physics, engineering, biology and medicine, from autocatalytic reaction systems to switched systems to cellular biochemical processes to malaria transmission in urban environments, exhibit the properties described by dynamics with choice. We study the long-term behaviour in dynamics with choice. We prove very general results on the existence and properties of global compact attractors in dynamics with choice. In addition, we study the dynamics with restricted choice when the allowed sequences of operators correspond to subshifts of the full shift. One of the practical consequences of our results is that when the parameters of a discrete-time system are not known exactly and/or are subject to change due to internal instability or a strategy or Nature's intervention, the long-term behaviour of the system may not be correctly described by a system with 'averaged' values for the parameters. There may be a Gestalt effect.
An invariant subspace theorem

Abstract In this paper it is proved that every operator on a complex Hilbert space whose spectrum is a spectral set has a nontrivial invariant subspace.
Resonance Effects for a Crack Near a Free Surface

Calcul des facteurs d'intensite de contrainte pour une fissure horizontale sous la surface soumise a une excitation harmonique. Determination des potentiels de deplacement qui satisfont des equations d'onde reduites et des conditions aux limites donnees. On obtient un systeme d'equations integrales couplees pour les densites de dislocations. La resolution numerique de ces equations conduit directement aux facteurs d'intensite de contraintes. Pour des valeurs particulieres de la frequence, on observe un effet de resonance
Quantum electrodynamics of particles on a plane and the Chern-Simons theory

Abstract We study the electrodynamics of generic charged particles (bosons, fermions, relativistic or not) constrained to move on an infinite plane. An effective gauge theory in (2 + 1)- dimensional space-time which describes the real electromagnetic interaction of these particles is obtained. The relationship between this effective theory with the Chern-Simons theory is explored. It is shown that the QED lagrangian per se produces the Chern-Simons constraint relating the current to the effective gauge field in 2 + 1 dimensions. It is also shown that the geometry of the system unavoidably induces a contribution from the topological θ- term that generates an explicit Chern-Simons term for the effective (2 + 1)-dimensional gauge field as well as a minimal coupling of the matter to it. The possible relation of the effective three-dimensional theory with the bosonization of the Dirac fermion field in 2 + 1 dimensions is briefly discussed as well as the potential applications in condensed matter systems.
Modification of sialyl residues of glycoconjugates by reductive amination. Characterization of the modified sialic acids

The sialic acid residues of alpha 1-acid glycoprotein and fetuin were modified by introduction of an amino residue, such as glycine and [3H]glycine. This modification involved (a) the selective periodate oxidation of the exocyclic carbon atoms of the sialic acid residue generating an aldehyde group at C-7, and (b) the reduction of the Schiff base formed with an amino compound by use of sodium cyanoborohydride. Thin layer chromatography, high pressure liquid chromatography, and amino acid composition data of the modified glycoprotein showed that the conversion was essentially quantitative. The glycine-modified sialic acids were isolated by mild acid hydrolysis and identified by g.l.c.-m.s. and n.m.r. spectroscopy, thus confirming that the quantitative modification produced a glycine-aminated C-7 sialic acid analog. Strong acid hydrolysis of the glycine-modified sialic acid yielded a fragment that had chromatographic characteristics similar to those of glycine.
Functional group selectivity in reactions of epoxides with tungsten hexachloride

Abstract The reactivity of several cyclohexene oxides bearing various functional groups toward the reagent tungsten hexachloride is reported. In general, the conversion of the epoxide to the trans dichloride occurs relatively rapidly. Several groups proved stable—esters, sulfides, sulfones, hindered silyl ethers—while others were unstable—alcohols, unhindered silyl ethers, ketones. The diaxial dichloride is usually formed although the diequatorial dichloride could also be prepared.
Crossed Products of the Cantor Set by Free Minimal Actions of Z d

Let d be a positive integer, let X be the Cantor set, and let ℤd act freely and minimally on X. We prove that the crossed product C*(ℤd,X) has stable rank one, real rank zero, and cancellation of projections, and that the order on K0(C*(ℤd,X)) is determined by traces. We obtain the same conclusion for the C*-algebras of various kinds of aperiodic tilings.
The Diverse Stellar Populations of the W3 Star-forming Complex

An ~800 arcmin2 mosaic image of the W3 star-forming complex obtained with the Chandra X-Ray Observatory gives a valuable new view of the spatial structure of its young stellar populations. The Chandra image reveals ~1300 faint X-ray sources, most of which are pre-main-sequence (PMS) stars in the cloud. Some, but not all, of the high-mass stars producing hypercompact and ultracompact H II (UC H II) regions are also seen, as reported in a previous study. The Chandra images reveal three dramatically different embedded stellar populations. The W3 Main cluster extends over 7 pc with ~900 X-ray stars in a nearly spherical distribution centered on the well-studied UC H II regions and high-mass protostars. The cluster surrounding the prototypical UC H II region W3(OH) shows a much smaller (≤0.6 pc), asymmetrical, and clumpy distribution of ~50 PMS stars. The massive star ionizing the W3 North H II region is completely isolated without any accompanying PMS stars. In W3 Main, the inferred ages of the widely distributed PMS stars are significantly older than the inferred ages of the central OB stars illuminating the UC H II regions. We suggest that different formation mechanisms are necessary to explain the diversity of the W3 stellar populations: cluster-wide gravitational collapse with delayed OB star formation in W3 Main, collect-and-collapse triggering by shock fronts in W3(OH), and a runaway O star or isolated massive star formation in W3 North.
TERMINOLOGY OF ACID‐BASE DISORDERS

Excerpt This paper attempts to present a brief, hopefully impartial, summary of the general terminological problems involved in the description and characterization of acid-base disorders. This is ...
Recalculation of data on the thermal decomposition of 1,1‐difluoroethane and 1,1,1‐trifluoroethane

Disagreements in rate constants and parameters between published results on the decomposition of 1,1-difluoroethane and 1,1,1-trifluoroethane are shown to originate from incorrect specification and setting of reaction conditions in one of the studies. When corrected, applicable results are in excellent agreement.
Uncertainty in measurements of distance

Ng and van Dam have argued that quantum theory and general relativity give a lower bound Δl l1/3lP2/3 on the uncertainty of any distance, where l is the distance to be measured and lP is the Planck length. Their idea is roughly that to minimize the position uncertainty of a freely falling measuring device, one must increase its mass, but if its mass becomes too large it will collapse to form a black hole. Here we show that one can go below the Ng–van Dam bound by attaching the measuring device to a massive elastic rod. Relativistic limitations on the rod's rigidity, together with the constraint that its length exceeds its Schwarzschild radius, imply that zero-point fluctuations of the rod give an uncertainty Δl lP.
Demand for insurance in a portfolio setting

This paper takes an additional step toward analyzing the demand for insurance in the context of a portfolio model. An investor is endowed with a portfolio containing a risky and riskless asset that can be augmented by purchasing insurance. Here, insurance is paid for by reducing the quantity of the risky insurable asset, holding the quantity of the riskless asset fixed. In the standard insurance demand model, insurance is paid for by reducing the amount of the riskless asset. This distinction leads to a different insurance demand function because the opportunity cost of purchasing insurance is now random.
Multiple pion production from an oriented chiral condensate

Abstract We consider an “oriented” chiral condensate produced in the squeezed states of the effective field theory with time- and space-dependent pion mass parameter. We discuss the general properties of the solution, identifying condensate modes and determining the resulting pion distributions. The implementation of the dynamics in the form of sudden perturbation allows us to look for exact solutions. In the region of condensation, the dramatic increase in pion production and charge fluctuations are demonstrated.
The Influence of Interim Auditor Reviews on the Association of Returns with Earnings

The Securities and Exchange Commission now requires auditors to review interim earnings reports on a timely basis. Previously, auditors could perform this review retrospectively, as part of the year‐end audit. We investigate whether timely reviews are likely to increase the relevance and reliability of reported earnings, as reflected by the extent to which the earnings‐return relation is contemporaneous. We find that when the auditor reviews interim earnings on a timely basis, the association between quarterly returns and earnings (and between quarterly returns and unexpected earnings) is predominantly contemporaneous. When the auditor reviews interim earnings retrospectively, however, the association between quarterly returns and earnings is not entirely contemporaneous; with retrospective reviews, returns lead interim earnings. We conclude from these findings that timely reviews increase the likelihood that accounting earnings reflect economic events contemporaneously with returns.
Diagnosis and reduction of conducted noise emissions

A systematic method for the diagnosis and reduction of conducted noise emissions is described. The method consists of a device for determining whether the differential- or common-mode component of conducted noise is dominant along with a simplified equivalent circuit of the power supply filter for each component. The procedure consists of first using the device to determine which noise-component is dominant in a particular frequency range and then using the simplified equivalent circuits to determine whether an anticipated change in value of an element in the power supply filter will be effective. >
Chief executive officers and voluntary environmental performance: Costa Rica's certification for sustainable tourism

This study evaluates whether the education, environmental expertise, and nationality of firms' chief executive officers (CEOs) are associated with greater participation and environmental performance in a voluntary environmental program implemented in a developing nation. Specifically, we collected data from the Certification for Sustainable Tourism (CST) program, a voluntary initiative aimed at promoting beyond-compliance environmental performance by hotels operating in Costa Rica. Our findings suggest that CEOs' level of formal education and environmental expertise appear to be significantly associated with higher corporate participation in voluntary programs and also with higher beyond-compliance environmental performance ratings. Contrary to conventional expectations, CEOs from industrialized countries (as opposed to developing countries) do not appear to show a statistically significant association with participation in the CST program and with higher beyond-compliance environmental performance.
Particle Filtering for Attitude Estimation Using a Minimal Local-Error Representation

A computationally efficient spacecraft attitude estimation particle filter is derived. The quaternion is used to represent the global attitude and the modified Rodrigues parameters are used to represent the local errors. The mean attitude is computed through the weighted sum of the modified Rodrigues parameter particles. The idea of progressive correction is employed to ensure the proper operation of the particle filter. Simulation results indicate that the performance of the particle filter exceeds that of the extended Kalman filter or the unscented Kalman filter for very large initialization errors.
Plasma properties and performance of mercury ion thrusters

Electron bombardment mercury ion thrustor plasma properties and performance, computing ion beam current, discharge losses and propellant utilization efficiency
Allylic C−H Amination for the Preparation of syn-1,3-Amino Alcohol Motifs

A highly selective and general Pd/sulfoxide-catalyzed allylic C−H amination reaction en route to syn-1,3-amino alcohol motifs is reported. Key to achieving this reactivity under mild conditions is the use of electron-deficient N-nosyl carbamate nucleophiles that are thought to promote functionalization by furnishing higher concentrations of anionic species in situ. The reaction is shown to be orthogonal to classical C−C bond-forming/-reduction sequences as well as nitrene-based C−H amination methods.
Are there gender, racial or relationship differences in caregiver task difficulty, depressive symptoms and life changes among stroke family caregivers?

AbstractObjective: To examine differences in caregiver perceptions of task difficulty, depressive symptoms and life changes based on caregiver characteristics of gender, race and type of relationship to the person with stroke.Methods: A sample of 243 stroke caregivers (females n = 191; males n = 52; non-African Americans n = 184; African Americans n = 59; non-spouses n = 127; spouses n = 116) were interviewed by telephone within 8 weeks of the survivor’s discharge to home. Measures included the Oberst Caregiving Burden Scale (OCBS) for task difficulty, Patient Health Questionnaire (PHQ-9) for depressive symptoms and Bakas Caregiving Outcomes Scale (BCOS) for life changes. Three general linear models computed differences in OCBS, PHQ9 and OCBS scores.Results: Significant differences were found on the OCBS for females (p < 0.001) and African American spouses (p < 0.048); on the PHQ9 for females (p < 0.001), non-African Americans (p = 0.047), spouses (p = 0.003) and African-American spouses (p = 0.010); and ...
Optimal Prediction in an Additive Functional Model

The functional generalized additive model (FGAM) provides a more flexible nonlinear functional regression model than the well-studied functional linear regression model. This paper restricts attention to the FGAM with identity link and additive errors, which we will call the additive functional model, a generalization of the functional linear model. This paper studies the minimax rate of convergence of predictions from the additive functional model in the framework of reproducing kernel Hilbert space. It is shown that the optimal rate is determined by the decay rate of the eigenvalues of a specific kernel function, which in turn is determined by the reproducing kernel and the joint distribution of any two points in the random predictor function. For the special case of the functional linear model, this kernel function is jointly determined by the covariance function of the predictor function and the reproducing kernel. The easily implementable roughness-regularized predictor is shown to achieve the optimal rate of convergence. Numerical studies are carried out to illustrate the merits of the predictor. Our simulations and real data examples demonstrate a competitive performance against the existing approach.
Shapes and textures of ferromagnetic liquid droplets

Theoretical calculations, computer simulations and experiments indicate the possible existence of a ferromagnetic liquid state. Should such a state exist, demagnetization effects would force a nontrivial magnetization texture governed by the shape of the liquid droplet. Since liquid droplets are deformable, the droplet shape couples to the magnetization texture. This paper solves the joint shape/texture problem subject to the assumption of cylindrical droplet symmetry. The shape undergoes a change in topology from spherical to toroidal as exchange energy grows or surface tension decreases.
Conditional risk–return relationship in a time-varying beta model

We investigate the asymmetric risk–return relationship in a time-varying beta CAPM. A state space model is established and estimated by the Adaptive Least Squares with Kalman foundations proposed by McCulloch. Using S&P 500 daily data from 1987:11–2003:12, we find a positive risk–return relationship in the up market (positive market excess returns) and a negative relationship in the down market (negative market excess returns). This supports the argument of Pettengill et al., who use a constant beta model. However, our model outperforms theirs by eliminating the unexplained returns and improving the accuracy of the estimated risk price.
Vacuum effects on fatigue properties of magnesium and two magnesium alloys.

High vacuum environment and vacuum outgassing time effects on magnesium alloys fatigue properties under constant load and reversed bending
VLBA Observations of z > 4 Radio-loud Quasars

We present high-resolution (≤20 mas) observations of the radio continuum emission at 1.4 GHz from three high-redshift quasars: J1053-0016 (z = 4.29), J1235-0003 (z = 4.69), and J0913+5919 (z = 5.11), thereby doubling the number of z > 4 radio-loud quasars that have been imaged at milliarcsecond resolution. The observations were carried out with the Very Long Baseline Array (VLBA) of the NRAO. All three sources are unresolved in these observations, with source size limits of a few milliarcseconds. In all cases the flux densities measured by the VLBA are within 10% of those measured with the Very Large Array (VLA), implying that the sources are not highly variable on yearly time scales. We find no indication for multiple images that might be produced by strong gravitational lensing on scales from 20 mas (VLBA) to a few arcseconds (VLA), to dynamic range limits of ~100.
Tracing conformational changes in proteins

Many proteins undergo extensive conformational changes as part of their functionality. Tracing these changes is important for understanding the way these proteins function. Traditional biophysics-based conformational search methods require a large number of calculations and are hard to apply to large-scale conformational motions. In this work we investigate the application of a robotics-inspired method, using backbone and limited side chain representation and a coarse grained energy function to trace large-scale conformational motions. We tested the algorithm on four well known medium to large proteins and we show that even with relatively little information we are able to trace low-energy conformational pathways efficiently. The conformational pathways produced by our methods can be further filtered and refined to produce more useful information on the way proteins function under physiological conditions. The proposed method effectively captures large-scale conformational changes and produces pathways that are consistent with experimental data and other computational studies. The method represents an important first step towards a larger scale modeling of more complex biological systems.
PULSED ALFVÉN WAVES IN THE SOLAR WIND

Using 3 s plasma and magnetic field data from the Wind spacecraft located in the solar wind well upstream from Earth, we report observations of isolated, pulse-like Alfvenic disturbances in the solar wind. These isolated events are characterized by roughly plane-polarized rotations in the solar wind magnetic field and velocity vectors away from the directions of the underlying field and velocity and then back again. They pass over Wind on timescales ranging from seconds to several minutes. These isolated, pulsed Alfven waves are pervasive; we have identified 175 such events over the full range of solar wind speeds (320-550 km s{sup -1}) observed in a randomly chosen 10 day interval. The large majority of these events are propagating away from the Sun in the solar wind rest frame. Maximum field rotations in the interval studied ranged from 6 Degree-Sign to 109 Degree-Sign . Similar to most Alfvenic fluctuations in the solar wind at 1 AU, the observed changes in velocity are typically less than that predicted for pure Alfven waves (Alfvenicity ranged from 0.28 to 0.93). Most of the events are associated with small enhancements or depressions in magnetic field strength and small changes in proton number density and/or temperature.more » The pulse-like and roughly symmetric nature of the magnetic field and velocity rotations in these events suggests that these Alfvenic disturbances are not evolving when observed. They thus appear to be, and probably are, solitary waves. It is presently uncertain how these waves originate, although they may evolve out of Alfvenic turbulence.« less
The role of echinocandins, extended-spectrum azoles, and polyenes to treat opportunistic moulds and Candida

Three classes of antifungals—polyenes, extended-spectrum azoles, and echinocandins—are now available for treating systemic fungal infections. Guidance for the appropriate use of this expanded variety of antifungals may come from recent clinical trials. Extended-spectrum azoles have excellent in vitro activity against Aspergillus and have been shown to improve clinical outcomes. For Zygomycetes, along with the lipid formulations of amphotericin, of the new agents, only posaconazole has activity. For Candida, the echinocandins offer a broad spectrum of activity. These new agents offer less toxicity and potentially improved efficacy in these difficult infections.
Critical care management of subarachnoid hemorrhage

Successful critical care management of patients with aneurysmal subarachnoid hemorrhage (SAH) requires a thorough understanding of the disease and its complications and a familiarity with modern multimodality neuromonitoring technology. This article reviews the natural history of aneurysmal SAH and strategies for disease management in the acute setting, including available tools for monitoring brain function. Intensive care management of patients with SAH focuses on prevention of further neurologic injury. Aneurysmal rebleeding, hydrocephalus, seizures, and delayed ischemic injury represent major threats. There is increasing awareness of extracerebral complications, including electrolyte disturbances (eg, cerebral salt wasting) and cardiac dysfunction. Prompt recognition and treatment of these disorders maximizes the odds of a good functional outcome. Technologic advances hold the promise of improved detection and treatment of secondary neurologic insults.
Formation of supermassive black holes

Evidence shows that massive black holes reside in most local galaxies. Studies have also established a number of relations between the MBH mass and properties of the host galaxy such as bulge mass and velocity dispersion. These results suggest that central MBHs, while much less massive than the host (~0.1%), are linked to the evolution of galactic structure. In hierarchical cosmologies, a single big galaxy today can be traced back to the stage when it was split up in hundreds of smaller components. Did MBH seeds form with the same efficiency in small proto-galaxies, or did their formation had to await the buildup of substantial galaxies with deeper potential wells? I briefly review here some of the physical processes that are conducive to the evolution of the massive black hole population. I will discuss black hole formation processes for ‘seed’ black holes that are likely to place at early cosmic epochs, and possible observational tests of these scenarios.
Efficient Solar‐Driven Synthesis, Carbon Capture, and Desalinization, STEP: Solar Thermal Electrochemical Production of Fuels, Metals, Bleach

STEP (solar thermal electrochemical production) theory is derived and experimentally verified for the electrosynthesis of energetic molecules at solar energy efficiency greater than any photovoltaic conversion efficiency. In STEP the efficient formation of metals, fuels, chlorine, and carbon capture is driven by solar thermal heated endothermic electrolyses of concentrated reactants occuring at a voltage below that of the room temperature energy stored in the products. One example is CO(2) , which is reduced to either fuels or storable carbon at a solar efficiency of over 50% due to a synergy of efficient solar thermal absorption and electrochemical conversion at high temperature and reactant concentration. CO(2) -free production of iron by STEP, from iron ore, occurs via Fe(III) in molten carbonate. Water is efficiently split to hydrogen by molten hydroxide electrolysis, and chlorine, sodium, and magnesium from molten chlorides. A pathway is provided for the STEP decrease of atmospheric carbon dioxide levels to pre-industial age levels in 10 years.
A Pressure-Based Method for Turbulent Cavitating Flow Computations

A pressure-based algorithm is presented for turbulent cavitating flow computations. Single-fluid Navier?Stokes equations cast in their conservative form, along with a volume fraction transport equation, are employed. The flow field is computed in both phases with the vapor pressure recovered inside the cavity via a mass transfer model. A pressure?velocity?density coupling scheme is developed to handle the large density ratio associated with cavitation. While no temperature, and hence Mach number, effect is considered in the cavitation model, the resulting pressure?correction equation shares common features with that of high-speed flows, exhibiting a convective?diffusive type, instead of only a diffusive type. Furthermore, similar to high-speed cases, upwinded density interpolation in mass flux computations also aids convergence of the cavitating flow computations. The nonequilibrium effect in the context of the k-? turbulence model, the grid distribution, and the choice of convection schemes have been computationally examined in projectile flows. While satisfactory predictions in wall pressure distribution can be made with variations in grid resolution and parameters in the cavitation model, other aspects, such as the density distribution and detailed streamline characteristics, are found to exhibit higher sensitivity to them.
Limits of correctness in computers

On October 5, 1960, the American Ballistic Missile Early-Warning System station at Thule, Greenland, indicated a large contingent of Soviet missiles headed towards the United States [1]. Fortunately, common sense prevailed at the informal threat-assessment conference that was immediately convened: international tensions weren’t particularly high at the time, the system had only recently been installed, Kruschev was in New York, and all in all a massive Soviet attack seemed very unlikely. As a result no devastating counter-attack was launched. What was the problem? The moon had risen, and was reflecting radar signals back to earth. Needless to say, this lunar reflection hadn’t been predicted by the system’s designers.
SYNTHESIS OF UNSYMMETRIC CYCLIC UREA DIOLS, A NOVEL CLASS OF HIV PROTEASE INHIBITORS

Abstract Unsymmetric cyclic urea diols of general structure 1 can be prepared either via an isourea derived from the symmetric diamine 2 or by the selective removal of a benzyl group from certain symmetric cyclic ureas 8, employing dissolving metal reduction.
A wide dynamic range integrator/discriminator/timer chip set for PMT applications

We have designed, fabricated and tested a full custom analog bipolar chip set for front end readout of the 10000 PMT Sudbury Neutrino Observatory. Each chip set instruments four independent PMT's with two self-gating integrator (HI/LO) channels, a fast discriminator and a timing sequence with three programmable intervals. The chip set provides a companion CMOS time to voltage converter (TVC) and analog memory chip with two programmable integration gates and a fixed width pulse suitable for time measurement and trigger processing. Novel features such as an internal 12 ns analog delay and an early voltage compensation network are discussed along with a short description of the basic circuit functions. >
Alternative Demand for University Outreach Services from Georgia's Golf Industry

Recent technological advancements have influenced farmers' growing demand for private information suppliers, a service traditionally monopolized by public outreach programs of land grant educational institutions. This waning appeal for university extension services creates pressure for these institutions to explore other market segments to broaden their audience coverage. This study demonstrates a potential market niche in Georgia's golf industry for university outreach services. Binomial logistic regression results indicate that significant demand (a) is negatively influenced by golf facility size; (b) is directly related to the level of industry experience of the golf superintendents; and (c) could come from facilities that require assistance in growth-, pest-, and employment-related concerns.
MyD88 signalling in colonic mononuclear phagocytes drives colitis in IL-10-deficient mice

Commensal bacterial sensing by Toll-like receptors is critical for maintaining intestinal homeostasis, but can lead to colitis in the absence of interleukin-10. Although Toll-like receptors are expressed in multiple cell types in the colon, the cell type(s) responsible for the development of colitis are currently unknown. Here we generated mice that are selectively deficient in MyD88 in various cellular compartments in an interleukin-10(-/-) setting. Although epithelial expression of MyD88 was dispensable, MyD88 expression in the mononuclear phagocyte compartment was required for colitis development. Specifically, phenotypically distinct populations of colonic mononuclear phagocytes expressed high levels of interleukin-1β, interleukin-23 and interleukin-6, and promoted T-helper 17 responses in the absence of interleukin-10. Thus, gut bacterial sensing through MyD88 in mononuclear phagocytes drives inflammatory bowel disease when unopposed by interleukin-10.
Structure and Unusual Magnetic Properties of YbMn0.17Si1.88

YbMn0.17Si1.88 was synthesized from the reaction of ytterbium, manganese, and silicon using indium as a flux. The average structure of YbMn0.17Si1.88 was refined in the monoclinic space group P21, with a = 4.0107(8) A, b = 3.8380(8) A, c = 14.458(3) A, β = 97.97(3)°, R1/wR2 = 0.0296/0.0720. The structure can be described as the intergrowth of three AlB2-type layers and one BaAl4-type layer. Magnetic susceptibility measurements suggest that the ytterbium atoms in YbMnxSi2-x exist in a mixed valent or intermediate valent state. YbMn0.17Si1.88 shows weak antiferromagnetic ordering below ∼4.5 K. The magnetic interactions between the Mn and Yb atoms in YbMn0.17Si1.88 are evident from the magnetic susceptibility measurements performed at low field. A negative magnetization is observed on warming and a positive magnetization on cooling. The heat capacity data suggest moderate heavy fermion behavior.
1,2-cis Alkyl glycosides: straightforward glycosylation from unprotected 1-thioglycosyl donors

A 1,2-cis-alkyl glycosidation protocol that makes use of unprotected phenyl 1-thioglycosyl donors is reported. Glycosylation of various functionalized alcohols was accomplished in moderate to high yield and selectivity to give the 1,2-cis-glycosides. In order to quickly develop optimum glycosylation conditions, an FIA (flow injection analysis)–ESI-TOF-MS method was developed that enabled rapid and quantitative evaluation of yield on small scale. This methodology, coupled with NMR spectroscopy, allowed for rapid evaluation of the overall reactions.
A Phase I-II study of 96-hour infusional topotecan and paclitaxel for patients with recurrent Müllerian tumors.

BACKGROUND Topotecan and paclitaxel are schedule dependent chemotherapeutic agents with activity against ovarian carcinoma. A Phase I–II study in which both drugs were administered concurrently by 96-hour, continuous, intravenous infusion was performed to determine the maximum tolerated dose (MTD), toxicities, pharmacokinetics, and efficacy of the combination. METHODS Women with ovarian or primary peritoneal carcinoma and documented recurrent disease were eligible for the study. The dose of topotecan was escalated from 1.6 mg/m2 while maintaining the paclitaxel dose constant at 100 mg/m2. Plasma concentrations of both drugs were monitored daily during the first cycle of therapy. RESULTS Forty-five patients with a median age of 54 years (range, 42–70 years) received 181 cycles of therapy. Five patients were recruited to each of four dose levels (topotecan 1.6 mg/m2, 2.0 mg/m2, 2.8 mg/m2, and 3.6 mg/m2), and an additional 25 patients were treated at the MTD (Phase II). Neutropenia and thrombocytopenia became dose limiting toxicities (DLT) at the fourth dose level. Emesis, mucositis, peripheral neuropathy, diarrhea, and alopecia were mild. Twenty patients (44%) had line-related occlusion, thrombosis, or infection. The mean values (± standard deviation) of the apparent steady-state plasma concentrations at the Phase II doses were 2.3 nM ± 0.5 nM for topotecan lactone, 5.6 nM ± 2.1 nM for total topotecan, and 40.1 nM ± 16.8 nM for paclitaxel. There were seven partial responses (Phase II) contributing to an objective response rate of 28% and a median survival time of 11.7 months (range, 0.6–20.1 months). CONCLUSIONS Topotecan at a dose of 2.8 mg/m2 and paclitaxel at a dose of 100 mg/m2 administered by concurrent, 96-hour, continuous intravenous infusions shows activity against tumors of Mullerian origin. Cancer 2001;92:1156–67. © 2001 American Cancer Society.
Compiler transformations for high-performance computing

In the last three decades a large number of compiler transformations for optimizing programs have been implemented. Most optimizations for uniprocessors reduce the number of instructions executed by the program using transformations based on the analysis of scalar quantities and data-flow techniques. In contrast, optimizations for high-performance superscalar, vector, and parallel processors maximize parallelism and memory locality with transformations that rely on tracking the properties of arrays using loop dependence analysis.This survey is a comprehensive overview of the important high-level program restructuring techniques for imperative languages, such as C and Fortran. Transformations for both sequential and various types of parallel architectures are covered in depth. We describe the purpose of each transformation, explain how to determine if it is legal, and give an example of its application.Programmers wishing to enhance the performance of their code can use this survey to improve their understanding of the optimizations that compilers can perform, or as a reference for techniques to be applied manually. Students can obtain an overview of optimizing compiler technology. Compiler writers can use this survey as a reference for most of the important optimizations developed to date, and as bibliographic reference for the details of each optimization. Readers are expected to be familiar with modern computer architecture and basic program compilation techniques.
Strategic transmission of information and short-term commitment

We examine the strategic role of information transmission in a repeated principal-agent relationship where the agent produces information that is useful to the principal. The agent values continuous employment for the principal because he makes a relationship-specific investment that can yield rents to him when the relationship is renewed. Assuming that the parties are sufficiently impatient, we show that full disclosure of the information produced occurs early in the relationship when the principal can commit to a long-term relationship, when the agent observes his valuation of continuous employment after making a report on information produced, or when the agent obtains a low valuation of continuous employment before making a report. By contrast, a strategic delay in the transmission of information occurs when the principal can only commit to a short-term relationship and the agent obtains a high valuation of continuous employment before making a report.