cssi/SciSciGPT-SciSciNet huggingface dataset:
Autonomous Aerobraking Using Thermal Response Surface Analysis

Aerobraking is a proven method of significantly increasing the science payload that can be placed into low Mars orbits when compared to an all propulsive capture. However, the aerobraking phase is long and has mission cost and risk implications. The main cost benefit is that aerobraking permits the use of a smaller and cheaper launch vehicle, but additional operational costs are incurred during the long aerobraking phase. Risk is increased due to the repeated thermal loading of spacecraft components and the multiple attitude and propulsive maneuvers required for successful aerobraking. Both the cost and risk burdens can be significantly reduced by automating the aerobraking operations phase. All of the previous Mars orbiter missions that have utilized aerobraking have increasingly relied on onboard calculations during aerobraking. Even though the temperature of spacecraft components has been the limiting factor, operational methods have relied on using a surrogate variable for mission control. This paper describes several methods, based directly on spacecraft component maximum temperature, for autonomously predicting the subsequent aerobraking orbits and prescribing apoapsis propulsive maneuvers to maintain the spacecraft within specified temperature limits. Specifically, this paper describes the use of thermal response surface analysis in predicting the temperature of the spacecraft components and the corresponding uncertainty in this temperature prediction.
Derivation and Validation of a Scoring System to Stratify Risk for Advanced Colorectal Neoplasia in Asymptomatic Adults: A Cross-sectional Study

Among persons at average risk for colorectal cancer, several screening methods are recommended equally, with no evidence-based preference. In this cross-sectional study, the authors developed an in...
Bregman Alternating Direction Method of Multipliers

The mirror descent algorithm (MDA) generalizes gradient descent by using a Bregman divergence to replace squared Euclidean distance. In this paper, we similarly generalize the alternating direction method of multipliers (ADMM) to Bregman ADMM (BADMM), which allows the choice of different Bregman divergences to exploit the structure of problems. BADMM provides a unified framework for ADMM and its variants, including generalized ADMM, inexact ADMM and Bethe ADMM. We establish the global convergence and the O(1/T) iteration complexity for BADMM. In some cases, BADMM can be faster than ADMM by a factor of O(n/ln n) where n is the dimensionality. In solving the linear program of mass transportation problem, BADMM leads to massive parallelism and can easily run on GPU. BADMM is several times faster than highly optimized commercial software Gurobi.
Temporal Reliability of Willingness to Pay from the National Survey of Fishing, Hunting, and Wildlife- Associated Recreation

The US Fish and Wildlife Service's (USFWS) National Survey of Fishing, Hunting and Wildlife-Associated Recreation (FHWAR) has been a source of information on wildlife-related recreation since 1955. The contingent valuation method has been used to estimate willingness to pay for recreation trips in the 1980, 1985, 1991, 1996 and 2001 surveys. However, relatively little comparative analysis over time has been performed. Similar value elicitation formats were used in the 1991 and 1996 surveys for bass and trout fishing, deer hunting and nonconsumptive wildlife recreation. We statistically analyze these data to assess the temporal reliability of the willingness to pay. We control for the effects of trip quality and socioeconomic variables and find that willingness to pay is significantly lower in 1996 for each activity. A subtle, but important, change in the 1996 question format may drive the result of lower willingness to pay. 1 A previous version of this article was presented at the 129th annual meeting of ...
A three-family SU(6) type I compactification

Abstract We construct a four dimensional chiral N =1 space-time supersymmetric Type I vacuum corresponding to a compactification on a toroidal Z 2 ⊗ Z 2 ⊗ Z 3 orbifold. Using recent results in four dimensional orientifolds, we argue that this model has a well defined world-sheet description. An interesting feature of this model is that the gauge group contains an SU(6) subgroup with three chiral generations. Moreover, this model contains D5-branes and therefore corresponds to a non-perturbative heterotic vacuum. This is the first example of a consistent chiral N =1 supersymmetric string vacuum which is non-perturbative from the heterotic viewpoint, has a perturbative description in a dual theory, and possesses some phenomenologically interesting characteristics. We also compute the tree-level superpotential in this theory.
Should births be centralised in higher level hospitals? Experiences from regionalised health care in Finland

Please cite this paper as: Hemminki E, Heino A, Gissler M. Should births be centralised in higher level hospitals? Experiences from regionalised health care in Finland. BJOG 2011; DOI: 10.1111/j.1471-0528.2011.02977.x. Objective To describe: (i) trends in centralisation and unplanned out-of-hospital births; (ii) perinatal mortality by place of birth; and (iii) health and birth outcomes in areas served by hospitals of different levels. Design Cross-sectional analysis of medical birth register data. Setting Finland, from 1991 to 2008, and Uusimaa district from 2004 to 2008. Population All births. Methods In the hospital-based analysis, birthweight was adjusted by logistic regression. In the area-based analysis results were calculated according to where women lived, grouping them into areas served by different hospitals. The mother’s background characteristics were adjusted for by logistic regression. Main outcome measures Place of birth, unplanned out-of-hospital birth, perinatal mortality, newborn outcomes, and birth procedures. Results The number of birthing hospitals declined, the mean number of births per hospital increased, and more births, particularly high-risk births, occurred in university hospitals. Unplanned out-of-hospital births were rare, and their numbers increased in the 2000s, but regional differences declined. Perinatal mortality was higher in the university hospitals than in other hospitals, but after adjusting for birthweight, it was lower. Among children weighing more than 2500 g, mortality was similar for all hospital levels. In out-of-hospital births, perinatal mortality was much higher than in other children. The area-based analysis did not systematically show better or worse results for the areas served by lower level hospitals: after adjusting for the background characteristics of the mothers, all differences were found to be small. Conclusions The health and service data do not support the need to close down small hospitals in a regionalised system where there is a referral system that functions well.
Effect of Lisinopril and Atenolol on Aortic Stiffness in Patients on Hemodialysis

Background and objectives Whether improvements in arterial compliance with BP lowering are because of BP reduction alone or if pleiotropic effects of antihypertensive agents contribute remains unclear. It was hypothesized that, among patients on hemodialysis, compared with a β -blocker (atenolol), a lisinopril-based therapy will better reduce arterial stiffness. Design, setting, participants, & measurements Among 200 participants of the Hypertension in Hemodialysis Patients Treated with Atenolol or Lisinopril Trial, 179 patients with valid assessment of aortic pulse wave velocity at baseline (89 patients randomly assigned to open-label lisinopril and 90 patients randomly assigned to atenolol three times a week after dialysis) were included in the secondary analysis. Among them, 109 patients had a valid pulse wave velocity measurement at 6 months. Monthly measured home BP was targeted to Results Contrary to the hypothesis, atenolol-based treatment induced greater reduction in aortic pulse wave velocity relative to lisinopril (between drug difference, 14.8%; 95% confidence interval, 1.5% to 28.5%; P =0.03). Reduction in 44-hour ambulatory systolic and diastolic BP was no different between groups (median [25th, 75th percentile]; atenolol: −21.5 [−37.7, −7.6] versus lisinopril: −15.8 [−28.8, −1.5] mmHg; P =0.27 for systolic BP; −14.1 [−22.6, −5.3] versus −10.9 [−18.4, −0.9] mmHg, respectively; P =0.30 for diastolic BP). Between-drug difference in change of aortic pulse wave velocity persisted after adjustments for age, sex, race, other cardiovascular risk factors, and baseline ambulatory systolic BP but disappeared after adjustment for change in ambulatory systolic BP (11.8%; 95% confidence interval, −2.3% to 25.9%; P =0.10). Conclusions Among patients on dialysis, atenolol was superior in improving arterial stiffness. However, differences between atenolol and lisinopril in improving aortic stiffness among patients on hemodialysis may be explained by BP-lowering effects of drugs.
All flat manifolds are cusps of hyperbolic orbifolds

We show that all closed flat n-manifolds are dieomorphic to a cusp crosssection in a nite volume hyperbolic n + 1-orbifold. AMS Classication 57M50; 57R99
Gold-catalyzed intermolecular anti-markovnikov hydroamination of alkylidenecyclopropanes.

The cationic gold phosphine complex [{PCy2 (o-biphenyl)}Au(NCMe)](+) SbF6 (-) (Cy=cyclohexyl) catalyzes the intermolecular, anti-Markovnikov hydroamination reaction of monosubstituted and cis- and trans-disubstituted alkylidenecyclopropanes (ACPs) with imidazolidin-2-ones and other nucleophiles. This reaction forms 1-cyclopropyl alkylamine derivatives in high yield and with high regio- and diastereoselectivity. NMR spectroscopic analysis of gold π-ACP complexes and control experiments point to the sp hybridization of the ACP internal alkene carbon atom as controlling the regiochemistry of the ACP hydroamination reaction.
Encyclopedia Walkabouts with VisNomad: A New Visualization Tool Designed as an Aid for Textual Exploration

We present an original visualizer that allows users to travel through the network of pages of an early encyclopedia of computer science. The purpose of this tool is to better understand the relationship between concepts of computer science at an early stage in the development of the eld. The visualizer is written in Java, interfaces to a database server, and sports two dierent graphical representations, a tree and a graph that are logically connected. We present our design goals, our choices of implementations and the challenges encountered.
Otoscopic, cytological, and microbiological examination of the equine external ear canal

Otoscopic examination and cytology of the equine ear would be beneficial in diseases such as head trauma, headshaking, otitis externa secondary to otitis media, vestibular disease, aural neoplasia and aural pruritus secondary to parasites. In practice, otic examinations of horses are rarely done due to the perceived difficulty in visualizing the equine external ear canal and tympanic membrane, as well as the need for chemical restraint. In this study, the proximal external ear canal was examined in live horses using a handheld otoscope and in cadaver heads using video otoscopy. Visualization of the proximal ear canal of the sedated horse could be done with a handheld otoscope, but more sedation or general anaesthesia and a video otoscope would be required to adequately visualize the tympanic membrane in the live horse. The proximal ear canals of 18 horses were examined cytologically and cultured aerobically. In three horses, both ears were sampled. No cells or organisms were seen on cytological examination of 11/21 ears. Nine of the 21 ears were sterile when cultured. Ten of the 21 ears had mixed growth with low numbers of organisms (Corynebacterium sp. being most common). Two of the 21 ears had heavy growth of a single organism (Corynebacterium sp. and Staphylococcus intermedius, respectively). Equine cadaver heads were examined in cross-section by computed tomography (CT) imaging and histopathology in order to further understand the anatomy of the equine external ear canal. Equine practitioners should be aware that otic examination is possible and may provide important diagnostic information.
Neutron diffraction studies of magnetic and superconducting compounds

Neutron diffraction is an extremely valuable tool for the investigation of magnetic and superconducting materials, because of its ability to directly observe periodic magnetic structures, determine magnetic moment directions and magnitudes, to observe light elements that are otherwise difficult to locate from X-ray diffraction due to the strong scattering of heavy elements, or to distinguish nearby elements in the periodic chart. This talk will focus on recent studies of superconducting and magnetic oxides that may provide insight into the interaction of magnetism and superconductivity, and into important changes in other transport properties (colossal magneto-resistance, ionic conductivity, etc.). These materials appear to show promise for a wide range of applications, and the neutron studies may not only help to understand their properties, but may also provide direction for synthesis of compounds that may overcome the limitations of those already discovered. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Sequential Equilibria in Bayesian Games with Communication

We study the effects of communication in Bayesian games when the players are sequentially rational but some combinations of types have zero probability. Not all communication equilibria can be implemented as sequential equilibria. We define the set of strong sequential communication equilibria (SSCE) and characterize it. SSCE differs from the concept of sequential communication equilibrium (SCE) defined by Myerson [Myerson, R.B., 1986. Multistage games with communication. Econometrica 54, 323–358] in that SCE allows the possibility of trembles by the mediator. We show that these two concepts coincide when there are three or more players, but the set of SSCE may be strictly smaller than the set of SCE for two-player games.
Embeddings into Free Heyting Algebras and Translations into Intuitionistic Propositional Logic

We find a translation with particularly nice properties from intuitionistic propositional logic in countably many variables to intuitionistic propositional logic in two variables. In addition, the existence of a possibly-not-as-nice translation from any countable logic into intuitionistic propositional logic in two variables is shown. The nonexistence of a translation from classical logic into intuitionistic propositional logic which preserves ? and ? but not necessarily ? is proven. These results about translations follow from additional results about embeddings into free Heyting algebras.
o-Quinonoid heterocyclic compounds: Naphtho[2,3-c]thiophene revisited

Naphtho[2,3-c]thiophene (2) has been synthesized in high yield v/a a faerie base-catalyzed Pummerer reaction. Dilithiation and the reaction of the dilithiospecies with several electrophiles is reported. © 1998 Elsevier Science Ltd. All rights reserved.
Specification and estimation of a spatially and temporally autocorrelated seemingly unrelated regression model: application to crash rates in China

In transportation studies, variables of interest are often influenced by similar factors and have correlated latent terms (errors). In such cases, a seemingly unrelated regression (SUR) model is normally used. However, most studies ignore the potential temporal and spatial autocorrelations across observations, which may lead to inaccurate conclusions. In contrast, the SUR model proposed in this study also considers these correlations, making the model more behaviorally convincing and applicable to circumstances where a three-dimensional correlation exists, across time, space, and equations. An example of crash rates in Chinese cities is used. The results show that incorporation of spatial and temporal effects significantly improves the model. Moreover, investment in transportation infrastructure is estimated to have statistically significant effects on reducing severe crash rates, but with an elasticity of only −0.078. It is also observed that, while vehicle ownership is associated with higher per capita crash rates, elasticities for severe and non-severe crashes are just 0.13 and 0.18, respectively; much lower than one. The techniques illustrated in this study should contribute to future studies requiring multiple equations in the presence of temporal and spatial effects.
POLYNOMIAL-SIZE NONOBTUSE TRIANGULATION OF POLYGONS

We describe methods for triangulating polygonal regions of the plane so that no triangle has a large angle. Our main result is that a polygon with n sides can be triangulated with O(n2) nonobtuse triangles. We also show that any triangulation (without Steiner points) of a simple polygon has a refinement with O(n4) nonobtuse triangles. Finally we show that a triangulation whose dual is a path has a refinement with only O(n2) nonobtuse triangles.
Trace Estimates for Relativistic Stable Processes

In this paper, we study the asymptotic behavior, as the time t goes to zero, of the trace of the semigroup of a killed relativistic α-stable process in bounded C 1,1 open sets and bounded Lipschitz open sets. More precisely, we establish the asymptotic expansion in terms of t of the trace with an error bound of order t 2/α t −d/α for C 1,1 open sets and of order t 1/α t −d/α for Lipschitz open sets. Compared with the corresponding expansions for stable processes, there are more terms between the orders t −d/α and t (2−d)/α for C 1,1 open sets, and, when α ∈ (0, 1), between the orders t −d/α and t (1−d)/α for Lipschitz open sets.
A method for imposing surface stress and heat flux conditions in finite-difference models with steep terrain

A numerical implementation of the surface stress boundary condition is presented for finite-difference models in which the terrain slope and curvature cannot necessarily be considered small. The method involves reducing the discretized stress condition in terrain-following coordinates to a pair of coupled linear systems for the two horizontal velocity components at the boundary. The linear systems are then solved iteratively at each model time step to provide the unique boundary values of velocity consistent with the specified values of the stress. Similar methods are used to prescribe the normal flux of heat across the boundary. A related method for imposing stress conditions in two-dimensional vorticity–streamfunction models is also discussed. The effectiveness of the boundary conditions is demonstrated through a series of test problems involving topographic wake flows and thermally driven flows on steep slopes. It is shown that the use of the conventional flat-boundary approximation can lead to substantial errors when the resolved topography is sufficiently steep.
Nanorheology of liquid alkanes

Abstract We report molecular dynamics simulations of liquid alkanes, squalane and tetracosane, confined between moving walls to which butane chains are tethered, effectively screening the details of the wall. As in an experiment, heat is removed by thermostatting the tethered molecules. Results obtained at high strain rates, typical of practical applications, suggest little or no difference between the bulk rheology and confined flow, and the occurrence of a high degree of slip at the wall–fluid interface at the conditions studied. At relatively low velocities and high densities, the tetracosane conformation becomes fully-extended at certain wall spacings.
Dirty Work, Clean Hands: The Moral Psychology of Indirect Agency

When powerful people cause harm, they often do so indirectly through other people. Are harmful actions carried out through others evaluated less negatively than harmful actions carried out directly? Four experiments examine the moral psychology of indirect agency. Experiments 1A, 1B, and 1C reveal effects of indirect agency under conditions favoring intuitive judgment, but not reflective judgment, using a joint/separate evaluation paradigm. Experiment 2A demonstrates that effects of indirect agency cannot be fully explained by perceived lack of foreknowledge or control on the part of the primary agent. Experiment 2B indicates that reflective moral judgment is sensitive to indirect agency, but only to the extent that indirectness signals reduced foreknowledge and/or control. Experiment 3 indicates that effects of indirect agency result from a failure to automatically consider the potentially dubious motives of agents who cause harm indirectly. Experiment 4 demonstrates an effect of indirect agency on purchase intentions.
Existentially Closed Models of the Theory of Artinian Local Rings

The class of all Artinian local rings of length at most l is ∀ 2 -elementary, axiomatised by a finite set of axioms τ t l . We show that its existentially closed models are Gorenstein. of length exactly l and their residue fields are algebraically closed, and, conversely, every existentially closed model is of this form. The theory o τ l of all Artinian local Gorenstein rings of length l with algebraically closed residue field is model complete and the theory τ t l is companionable, with model-companion o τ l .
The Effect of Weak Interface on Transverse Properties of a Ceramic Matrix Composite

Experimental studies conducted at the NASA Lewis Research Center on silicon carbide reaction-bonded silicon nitride composite system (SiC/RBSN) led to a significant observation regarding their unidirectional tensile properties. It was found that transverse stiffness and strength were much lower than those predicted from existing analytical models based on good interfacial bonding. Since the composite system was designed to have weakened interfaces to improve toughness, it was believed that these weakened interfaces were responsible for the decrease in transverse properties. To support this claim, a two dimensional finite element analysis was performed for a transverse representative volume element. Specifically, the effect of fiber/matrix displacement compatibility at the interface was studied under both tensile and compressive transverse loadings. Interface debonding was represented active gap elements connecting the fiber and matrix. The analyses show that the transverse tensile strength and stiffness are best predicted when a debonded interface is assumed for the composite. In fact, the measured properties can be predicted by simply replacing the fibers by voids. Thus, the following two conclusions are drawn from the present study: (1) little or no interfacial bonding exists in the SiC/RBSN composite; (2) an elastic analysis can predict the transverse stiffness and strength.
Dynamic Source Routing in Ad Hoc Wireless Networks

An ad hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. In such an environment, it may be necessary for one mobile host to enlist the aid of other hosts in forwarding a packet to its destination, due to the limited range of each mobile host’s wireless transmissions. This paper presents a protocol for routing in ad hoc networks that uses dynamic source routing. The protocol adapts quickly to routing changes when host movement is frequent, yet requires little or no overhead during periods in which hosts move less frequently. Based on results from a packet-level simulation of mobile hosts operating in an ad hoc network, the protocol performs well over a variety of environmental conditions such as host density and movement rates. For all but the highest rates of host movement simulated, the overhead of the protocol is quite low, falling to just 1% of total data packets transmitted for moderate movement rates in a network of 24 mobile hosts. In all cases, the difference in length between the routes used and the optimal route lengths is negligible, and in most cases, route lengths are on average within a factor of 1.01 of optimal.
The Structure of Galaxies I: Surface Photometry Techniques

This project uses the 2MASS all-sky image database to study the structure of galaxies over a range of luminosities, sizes and morphological types. This first paper in this series will outline the techniques, reliability and data products to our surface photometry program. Our program will analyze all acceptable galaxies (meeting our criteria for isolation from companions and bright stars) from the Revised Shapley–Ames and Uppsala galaxy catalogs. Resulting photometry and surface brightness profiles are released using a transparent scheme of data storage which includes not only all the processed data but knowledge of the processing steps and calibrating parameters.
Tidal evolution of Mimas, Enceladus, and Dione

The tidal evolution through several resonances involving Mimas, Enceladus, and/or Dione is studied numerically with an averaged resonance model. We find that, in the Enceladus–Dione 2:1 e-Enceladus type resonance, Enceladus evolves chaotically in the future for some values of k2/Q. Past evolution of the system is marked by temporary capture into the Enceladus–Dione 4:2 ee � -mixed resonance. We find that the free libration of the Enceladus–Dione 2:1 e-Enceladus resonance angle of 1.5 ◦ can be explained by a recent passage of the system through a secondary resonance. In simulations with passage through the secondary resonance, the system enters the current Enceladus–Dione resonance close to tidal equilibrium and thus the equilibrium value of tidal heating of 1.1(18,000/QS ) GW applies. We find that the current anomalously large eccentricity of Mimas can be explained by passage through several past resonances. In all cases, escape from the resonance occurs by unstable growth of the libration angle, sometimes with the help of a secondary resonance. Explanation of the current eccentricity of Mimas by evolution through these resonances implies that the Q of Saturn is below 100,000. Though the eccentricity of Enceladus can be excited to moderate values by capture in the Mimas–Enceladus 3:2 e-Enceladus resonance, the libration amplitude damps and the system does not escape. Thus past occupancy of this resonance and consequent tidal heating of Enceladus is excluded. The construction of a coherent history places constraints on the allowed values of k2/Q for the satellites.
Spike timing and the coding of naturalistic sounds in a central auditory area of songbirds

In nature, animals encounter high dimensional sensory stimuli that have complex statistical and dynamical structure. Attempts to study the neural coding of these natural signals face challenges both in the selection of the signal ensemble and in the analysis of the resulting neural responses. For zebra finches, naturalistic stimuli can be defined as sounds that they encounter in a colony of conspecific birds. We assembled an ensemble of these sounds by recording groups of 10-40 zebra finches, and then analyzed the response of single neurons in the songbird central auditory area (field L) to continuous playback of long segments from this ensemble. Following methods developed in the fly visual system, we measured the information that spike trains provide about the acoustic stimulus without any assumptions about which features of the stimulus are relevant. Preliminary results indicate that large amounts of information are carried by spike timing, with roughly half of the information accessible only at time resolutions better than 10 ms; additional information is still being revealed as time resolution is improved to 2 ms. Information can be decomposed into that carried by the locking of individual spikes to the stimulus (or modulations of spike rate) vs. that carried by timing in spike patterns. Initial results show that in field L, temporal patterns give at least ~ 20% extra information. Thus, single central auditory neurons can provide an informative representation of naturalistic sounds, in which spike timing may play a significant role.
Hand-Held Gamma-Ray Spectrometer Based on High-Efficiency Frisch-Ring CdZnTe Detectors

Frisch-ring CdZnTe detectors have demonstrated both good energy resolution, <1% FWHM at 662 keV, and good efficiency in detecting gamma rays, highlighting the strong potential of CdZnTe materials for such applications. We are designing a hand-held gamma-ray spectrometer based on Frisch-ring detectors at Brookhaven National Laboratory. It employs an 8 times 8 CdZnTe detector array to achieve a high volume of 19.2 cm3, so greatly improving detection efficiency. By using the front-end application-specific integrated circuits (ASICs) developed at BNL, this spectrometer has a small profile and high energy-resolution. It includes a signal processing circuit, digitization and storage circuits, a high-voltage module, and a universal serial bus (USB) interface. In this paper, we detail the system's structure and report the results of our tests with it.
Synthetic studies of the formation of pyrazoloisoquinolines

Abstract Diazotization of 7-amino-5,8-dimethyl-6-(phenylthio)isoquinoline unexpectedly led to the formation of a new ring system, 3H-pyrazolo[3,4-h]isoquinoline as its 5-methyl-6-phenylthio derivative. In this work, the parent ring system was synthesized and characterized, along with its 5-methyl, 6-bromo-5-methyl, and 5-methyl-6-phenylthio derivatives. The mechanism for the transformation is explored.
Probabilistic 3D Object Recognition

A probabilistic 3D object recognition algorithm is presented. In order to guide the recognition process the probability that match hypotheses between image features and model features are correct is computed. A model is developed which uses the probabilistic peaking effect of measured angles and ratios of lengths by tracing iso-angle and iso-ratio curves on the viewing sphere. The model also accounts for various types of uncertainty in the input such as incomplete and inexact edge detection. For each match hypothesis the pose of the object and the pose uncertainty which is due to the uncertainty in vertex position are recovered. This is used to find sets of hypotheses which reinforce each other by matching features of the same object with compatible uncertainty regions. A probabilistic expression is used to rank these hypothesis sets. The hypothesis sets with the highest rank are output. The algorithm has been fully implemented, and tested on real images.
Models of light reflection for computer synthesized pictures

In the production of computer generated pictures of three dimensional objects, one stage of the calculation is the determination of the intensity of a given object once its visibility has been established. This is typically done by modelling the surface as a perfect diffuser, sometimes with a specular component added for the simulation of hilights. This paper presents a more accurate function for the generation of hilights which is based on some experimental measurements of how light reflects from real surfaces. It differs from previous models in that the intensity of the hilight changes with the direction of the light source. Also the position and shape of the hilights is somewhat different from that generated by simpler models. Finally, the hilight function generates different results when simulating metallic vs. nonmetallic surfaces. Many of the effects so generated are somewhat subtle and are apparent only during movie sequences. Some representative still frames from such movies are included.
Revisiting Incentive Effects in Workers' Compensation: Do Higher Benefits Really Induce More Claims?:

An important question to ask regarding social insurance programs such as workers' compensation (WC) is to what extent do higher benefits lead to more claims? The authors of this study revisit incentive effects of WC, using 25 years of data (1977–2004) from the March Current Population Survey (CPS) to estimate the relationship between WC cash benefit levels and the frequency of WC receipt. Providing new evidence on the subject, they demonstrate that conclusions regarding workers' incentives to claim benefits differ dramatically depending upon how one controls for the confounding influence of an individual's past earnings. The authors' expanded empirical specifications, which include flexible earnings controls, yield benefit-participation elasticities smaller than 0.1. Their findings suggest that WC claims are not particularly responsive to changes in benefit levels and that labor supply disincentives may warrant less concern than economists or policymakers have typically exhibited. The authors also find th...
Role of escherichia coli YbeY, a highly conserved protein, in rRNA processing

The UPF0054 protein family is highly conserved with homologues present in nearly every sequenced bacterium. In some bacteria, the respective gene is essential, while in others its loss results in a highly pleiotropic phenotype. Despite detailed structural studies, a cellular role for this protein family has remained unknown. We report here that deletion of the Escherichia coli homologue, YbeY, causes striking defects that affect ribosome activity, translational fidelity and ribosome assembly. Mapping of 16S, 23S and 5S rRNA termini reveals that YbeY influences the maturation of all three rRNAs, with a particularly strong effect on maturation at both the 5'- and 3'-ends of 16S rRNA as well as maturation of the 5'-termini of 23S and 5S rRNAs. Furthermore, we demonstrate strong genetic interactions between ybeY and rnc (encoding RNase III), ybeY and rnr (encoding RNase R), and ybeY and pnp (encoding PNPase), further suggesting a role for YbeY in rRNA maturation. Mutation of highly conserved amino acids in YbeY, allowed the identification of two residues (H114, R59) that were found to have a significant effect in vivo. We discuss the implications of these findings for rRNA maturation and ribosome assembly in bacteria.
On the optimal convergence probability of univariate estimation of distribution algorithms

In this paper we obtain bounds on the probability of convergence to the optimal solution for the compact genetic algorithm (cGA) and the population based incremental learning (PBIL). Moreover, we give a sufficient condition for convergence of these algorithms to the optimal solution and compute a range of possible values for algorithm parameters at which there is convergence to the optimal solution with a predefined confidence level.
School meals, educational achievement, and school competition : evidence from a randomized evaluation

This brief summarizes the results of a gender impact evaluation study, entitled School meals, educational achievement, and school competition : evidence from a randomized evaluation, conducted between 2000 and 2002 in Kenya. The study observed the impact of subsidized school meals on school participation, educational achievement, and school finance in a developing country setting that was implemented in 25 randomly chosen preschools in a pool of 50 schools on the child level. The school feeding program had a positive significant impact on school participation (treated students participated in school 35.9 percent of the time versus 27.4 for the comparison group). The program led to a significant improvement in test scores, but only in schools where teachers were more experienced at the onset of the program. There was no impact on cognitive abilities. The program led to a significant improvement in the weight of boys, but no improvement in the height or weight of girls. The increased participation led to overcrowding, but had no impact on teacher absenteeism. Also, the school meals displaced teaching time. Funding for the study derived from the Dutch Non-Governmental Organization (NGO), Internationaal Christelijk Steunfonds (ICS).
Evolving New Protein-Protein Interaction Specificity through Promiscuous Intermediates.

Interacting proteins typically coevolve, and the identification of coevolving amino acids can pinpoint residues required for interaction specificity. This approach often assumes that an interface-disrupting mutation in one protein drives selection of a compensatory mutation in its partner during evolution. However, this model requires a non-functional intermediate state prior to the compensatory change. Alternatively, a mutation in one protein could first broaden its specificity, allowing changes in its partner, followed by a specificity-restricting mutation. Using bacterial toxin-antitoxin systems, we demonstrate the plausibility of this second, promiscuity-based model. By screening large libraries of interface mutants, we show that toxins and antitoxins with high specificity are frequently connected in sequence space to more promiscuous variants that can serve as intermediates during a reprogramming of interaction specificity. We propose that the abundance of promiscuous variants promotes the expansion and diversification of toxin-antitoxin systems and other paralogous protein families during evolution.
On X-Ray Variability in Active Binary Stars

We have compared the X-ray emissions of active binary stars observed at various epochs by the Einstein and ROSAT satellites in order to investigate the nature of their X-ray variability. The primary aim of this work is to determine whether or not active binaries exhibit long-term variations in X-ray emission, perhaps analogous to the observed cyclic behavior of solar magnetic activity. We find that, while the mean level of emission of the sample remains steady, comparison of different ROSAT observations of the same stars shows significant variation on timescales 2 yr, with an "effective variability" ΔI/I = 0.32 ± 0.04, where I and ΔI represent the mean emission and variation from the mean emission, respectively. A comparison of the ROSAT All-Sky Survey and later pointed observations with earlier observations of the same stars carried out with Einstein yields only marginal evidence for a larger variation (ΔI/I = 0.38 ± 0.04 for Einstein vs. ROSAT All-Sky Survey and 0.46 ± 0.05 for Einstein vs. ROSAT pointed) at these longer timescales (~10 yr), thus indicating the possible presence of a long-term component to the variability. Whether or not this long-term component is due to the presence of cyclic variability cannot be decided on the basis of existing data. However, assuming that this component is analogous to the observed cyclic variability of the Sun, we find that the relative magnitude of the cyclic component in the ROSAT passband can, at most, be a factor of 4, i.e., Icyc/Imin < 4. This is to be compared with the corresponding but significantly higher solar value of ~10-102 derived from GOES, Yohkoh, and Solrad data. These results are consistent with the suggestions of earlier studies that a turbulent or distributive dynamo might be responsible for the observed magnetic activity on the most active, rapidly rotating stars.
Deformation of a Peridynamic Bar

The deformation of an infinite bar subjected to a self-equilibrated load distribution is investigated using the peridynamic formulation of elasticity theory. The peridynamic theory differs from the classical theory and other nonlocal theories in that it does not involve spatial derivatives of the displacement field. The bar problem is formulated as a linear Fredholm integral equation and solved using Fourier transform methods. The solution is shown to exhibit, in general, features that are not found in the classical result. Among these are decaying oscillations in the displacement field and progressively weakening discontinuities that propagate outside of the loading region. These features, when present, are guaranteed to decay provided that the wave speeds are real. This leads to a one-dimensional version of St. Venant's principle for peridynamic materials that ensures the increasing smoothness of the displacement field remotely from the loading region. The peridynamic result converges to the classical result in the limit of short-range forces. An example gives the solution to the concentrated load problem, and hence provides the Green's function for general loading problems.
Novel Method for the Synthesis of 3′,4′‐Dideoxygenated Pyranmycin and Kanamycin Compounds, and Studies of Their Antibacterial Activity Against Aminoglycoside‐Resistant Bacteria

A novel protocol for converting a trans‐diol to an alkene under mild conditions was developed. This method led to the synthesis of a 3′,4′‐dideoxykanamycin (dibekacin) analog and a 3′,4′‐dideoxypyranmycin that were found to be active against aminoglycoside‐resistant bacteria.
OPTICAL PROBING OF PHOTOACOUSTIC PROPAGATION FOR NONCONTACT MEASUREMENT OF FLOWS, TEMPERATURES AND CHEMICAL COMPOSITIONS

Abstract : Noncontact techniques of optical probing of photoacoustic pulses provide new opportunities for ultrasonic and/or spectroscopic measurement in hostile environments (e.g., flames, corrosive fluids, dangerous aerosols, etc.) and also basic understanding of photoacoustic generation processes. This paper provides examples of such applications in the new field of 'optical ultrasonics' (whereby ultrasonic determinations of flows, temperatures, etc., are measured optically), including 'optical ultrasonic spectroscopy' (whereby ultrasonic dispersion and relaxations are measured optically).
Partial Adjustment or Stale Prices? Implications from Stock Index and Futures Return Autocorrelations

We investigate the relation between returns on stock indices and their corresponding futures contracts to evaluate potential explanations for the pervasive yet anomalous evidence of positive, short-horizon portfolio autocorrelations. Using a simple theoretical framework, we generate empirical implications for both microstructure and partial adjustment models. The major findings are (i) return autocorrelations of indices are generally positive even though futures contracts have autocorrelations close to zero, and (ii) these autocorrelation differences are maintained under conditions favorable for spot-futures arbitrage and are most prevalent during low-volume periods. These results point toward microstructure-based explanations and away from explanations based on behavioral models.
Capturing crossings: Convex hulls of segment and plane intersections

We give a simple O(nlogn) algorithm to compute the convex hull of the (possibly @Q(n^2)) intersection points in an arrangement of n line segments in the plane. We also show an arrangement of dn hyperplanes in d-dimensions whose arrangement has @Q(n^d^-^1) intersection points on the convex hull.
Copper-mediated difluoromethylation of (hetero)aryl iodides and β-styryl halides with tributyl(difluoromethyl)stannane.

Ca-mediated treatment of Bu3SnH with TmsCF3 allows an efficient access to the title stannane (III).
Do Loan Commitments Cause Overlending

I begin with a model that generates quantity credit rationing by banks in the spot credit market when the real interest rate is high and there is an economic downturn. Then I rationalize a bank loan commitment as partial insurance against such future rationing. Incorporating uncertainty about both the creditworthiness of borrowers and the abilities of banks to screen borrowers, I extend the bank contracting literature wherein I examine banks' decisions of whether to lend under the commitments sold earlier. I show that this discretion of whether to honor borrowing requests under commitments generates reputational concerns on the part of banks and can lead to an equilibrium in which loan commitments serve their role in increasing credit supply relative to the spot credit market, but produce the inefficiency of excessive credit supply when the real interest rate is low and the economy is doing well. Despite this, welfare is higher with loan commitments than with spot credit. Numerous empirical predictions and policy implications are drawn out.
A directive from history.

(1949). A Directive from History. Journal of the American Association for Health, Physical Education, and Recreation: Vol. 20, No. 8, pp. 514-550.
Compression-induced stiffness in the buckling of a one fiber composite

We study the buckling of a one fiber composite whose matrix stiffness is slightly dependent on the compressive force. We show that the equilibrium curves of the system exhibit a limit load when the induced stiffness parameter gets bigger than a threshold. This limit load increases when the stiffness parameter is increasing and it is related to a possible localized path in the post-buckling domain. Such a change in the maximum load may be very desirable from a structural stand point.
Initial Nucleation Study and New Technique for Sublimation Growth of AlN on SiC Substrate

Single crystal platelets of AlN were successfully grown on 6H-SiC(0001) by a novel technique designed to suppress SiC decomposition, promote two-dimensional growth, and eliminate cracking in the AlN. X-ray diffractometry and synchrotron white beam X-ray topography demonstrate that the final AlN single crystal is of high structural quality.
Oxidative cyclizations of allenic sulfonamides with dimethyldioxirane

Abstract The dimethyldioxirane oxidations of allenic amine derivatives give highly functionalized nitrogen heterocycles derived from cyclizations of intermediate allene mono- and diepoxides.
Robust stability analysis using Lyapunov density

We state and prove a robustness result for the concept of almost everywhere uniform stability of an invariant attractor for a nonlinear autonomous differential equation. We also show that the concept of almost everywhere uniform stability rectifies the drawback of vanishing density on stable manifolds of hyperbolic equilibrium points which exists for a weaker concept of almost everywhere stability.
The preparation of a stable 2-pyridylboronate and its reactivity in the Suzuki–Miyaura cross-coupling reaction

The preparation and reactivity of a 2-pyridylboronate stabilised by N-phenyldiethanolamine is described. In Suzuki–Miyaura cross-coupling reactions employing this boronate, significant aryl–aryl exchange from the phosphine ligand was observed with some combinations of ligand and substrates. The amount of the exchange by-product can be minimised by appropriate choice of phosphine ligand.
Phase change memory in enterprise storage systems: silver bullet or snake oil?

Storage devices based on Phase Change Memory (PCM) devices are beginning to generate considerable attention in both industry and academic communities. But whether the technology in its current state will be a commercially and technically viable alternative to entrenched technologies such as flash-based SSDs still remains unanswered. To address this it is important to consider PCM SSD devices not just from a device standpoint, but also from a holistic perspective.This paper presents the results of our performance measurement study of a recent all-PCM SSD prototype. The average latency for 4 KB random read is 6.7 ?s, which is about 16x faster than a comparable eMLC flash SSD. The distribution of I/O response times is also much narrower than the flash SSD for both reads and writes. Based on real-world workload traces, we model a hypothetical storage device which consists of flash, HDD, and PCM to identify the combinations of device types that offer the best performance within cost constraints. Our results show that - even at current price points - PCM storage devices show promise as a new component in multi-tiered enterprise storage systems.