cssi/SciSciGPT-SciSciNet huggingface dataset:
K-Band Properties of Galaxy Clusters and Groups: Luminosity Function, Radial Distribution, and Halo Occupation Number

We explore the near-infrared (NIR) K-band properties of galaxies within 93 galaxy clusters and groups using data from the Two Micron All Sky Survey. We use X-ray properties of these clusters to pinpoint cluster centers and estimate cluster masses. By stacking all these systems, we study the shape of the cluster luminosity function and the galaxy distribution within the clusters. We find that the galaxy profile is well described by the Navarro, Frenk, & White (NFW) profile with a concentration parameter c ~ 3, with no evidence for cluster mass dependence of the concentration. Using this sample, whose masses span the range from 3 × 1013 to 2 × 1015 M☉, we confirm the existence of a tight correlation between total galaxy NIR luminosity and cluster binding mass, which indicates that NIR light can serve as a cluster mass indicator. From the observed galaxy profile, together with cluster mass profile measurements from the literature, we find that the mass-to-light ratio is a weakly decreasing function of cluster radius and that it increases with cluster mass. We also derive the mean number of galaxies within halos of a given mass, the halo occupation number. We find that the mean number scales as N M0.84±0.04 for galaxies brighter than MK = -21, indicating that high-mass clusters have fewer galaxies per unit mass than low-mass clusters. Using published observations at high redshift, we show that higher redshift clusters have higher mean occupation numbers than nearby systems of the same mass. By comparing the luminosity function and radial distribution of galaxies in low-mass and high-mass clusters, we show that there is a marked decrease in the number density of galaxies fainter than M* as one moves to higher mass clusters; in addition, extremely luminous galaxies are more probable in high-mass clusters. We explore several processes, including tidal interactions and merging, as a way of explaining the variation in galaxy population with cluster mass.
Paying for What Was Free: Lessons from the New York Times Paywall

In a national online longitudinal survey, participants reported their attitudes and behaviors in response to the recently implemented metered paywall by the New York Times. Previously free online content now requires a digital subscription to access beyond a small free monthly allotment. Participants were surveyed shortly after the paywall was announced and again 11 weeks after it was implemented to understand how they would react and adapt to this change. Most readers planned not to pay and ultimately did not. Instead, they devalued the newspaper, visited its Web site less frequently, and used loopholes, particularly those who thought the paywall would lead to inequality. Results of an experimental justification manipulation revealed that framing the paywall in terms of financial necessity moderately increased support and willingness to pay. Framing the paywall in terms of a profit motive proved to be a noncompelling justification, sharply decreasing both support and willingness to pay. Results suggest that people react negatively to paying for previously free content, but change can be facilitated with compelling justifications that emphasize fairness.
Quark mass difference and the origin of charge symmetry breaking

Abstract Evidence for charge symmetry breaking in nuclear and particle physics is presented, and it is shown that all of the observed effects can be explained by the mass and electric charge difference between d and u quarks. While hadron masses depend on the sum of the quark masses, charge symmetry breaking effects depend on the difference between d and u quark masses, providing a new quark mass relation.
Black hole condensation and the unification of string vacua

Abstract It is argued that black hole condensation can occur at conifold singularities in the moduli space of type II Calabi-Yau string vacua. The condensate signals a smooth transition to a new Calabi-Yau space with different Euler characteristic and Hodge numbers. In this manner string theory unifies the moduli spaces of many or possibly all Calabi-Yau vacua. Elementary string states and black holes are smoothly interchanged under the transitions, and therefore cannot be invariantly distinguished. Furthermore, the transitions establish the existence of mirror symmetry for many many or possibly all Calabi-Yau manifolds.
Total asymmetric synthesis of the putative structure of the cytotoxic diterpenoid (-)-sclerophytin a and of the authentic natural sclerophytins A and B.

An enantioselective synthetic route to the thermodynamically most stable diastereomer of the structure assigned to sclerophytin A (5) has been realized. The required tricyclic ketone 33 was prepared by sequential Tebbe−Claisen rearrangement of lactones 29 and 30, which originated from the Diels−Alder cycloaddition of Danishefsky's diene to (5S)-5-(d-menthyloxy)-2(5H)-furanone (14). An allyl and a cyano group were introduced into the resulting adduct by means of stereocontrolled allylindation under aqueous Barbier-like conditions and by way of cyanotrimethylsilane, respectively. Following stereocontrolled nucleophilic addition of a methyl group to 33, ring A was elaborated by formation of the silyl enol ether, ytterbium triflate-catalyzed condensation with formaldehyde, O-silylation, and Cu(I)-promoted 1,4-addition of isopropylmagnesium chloride. The superfluous ketone carbonyl was subsequently removed and the second ether bridge introduced by means of oxymercuration chemistry. Only then was the exocyclic ...
Reliability and Convergent Validity of the National College Health Risk Behavior Survey Physical Activity Items

Abstract This study examined the reliability and validity of the National College Health Risk Behavior Survey (NCHRBS) vigorous physical activity (VPA), moderate physical activity (MPA), flexibility (FLEX), and muscular strength and/or endurance (MSE) questions. Twenty college students completed the four items twice during the same day. During the next 7 days they wore an accelerometer and a pedometer during all waking hours. They also recorded their daily activity in a log. At the end of the week, subjects completed the NCHRBS physical activity items again. The intraclass correlation coefficients ranged from .94–.99 for the four items. The vigorous item was highly correlated with log VPA (r=.82) and number of days with ≥20 minutes of VPA from the accelerometer (r=.60). The flexibility item was moderately correlated (r=.57) and the muscular strength and/or endurance item was highly correlated (r=.89) with corresponding log activities. The moderate item was highly correlated with log MPA (r=.66) and number...
The geoid spectrum from altimetry

Satellite altimetry information from the world's major oceans was analyzed to arrive at a geoid power spectrum. Using the equivalent of about 7 revolutions of data (mostly from GEOS-3) the power spectrum of the sea surface generally follows the expected values from Kaula's rule applied to the geoid. Analysis of overlapping altimetry arcs (and oceanographic data) shows that the surface spectrum is dominated by the geoid to about 500 cycles (40 km half wavelength) but that sea state departures are significant starting at about 250 cycles (80 km). Estimates of geopotential variances from a derived (smooth) geoid spectrum show significantly less power than Kaula's rule to about 60 cycles, but somewhat more from there to about 400 cycles. At less than 40 km half wavelength, the total power in the marine geoid may be negligible.
Applications of passive microwave observations of surface soil moisture

Abstract In large scale field experiments over the past 10 years, long wavelength microwave radiometers were used to map surface soil moisture with considerable success. These experiments, which include FIFE (87 & 89), Monsoon ‘90, Washita 92 and 94, and HAPEX-Sahel, covered a wide range of climatic regimes. The results from these experiments show that the microwave emission at the 21 cm wavelength is a strong function of surface (0–5 cm) soil moisture and thus can be used to map spatial and temporal variations of the moisture content of this soil layer. The salient results from these experiments will be presented and compared. The use of the surface soil moisture data to determine geophysical parameters such as evaporative fraction, soil evaporation and soil hydraulic properties will be discussed and results presented.
Wafer scale homogeneous bilayer graphene films by chemical vapor deposition.

The discovery of electric field induced band gap opening in bilayer graphene opens a new door for making semiconducting graphene without aggressive size scaling or using expensive substrates. However, bilayer graphene samples have been limited to μm2 size scale thus far, and synthesis of wafer scale bilayer graphene poses a tremendous challenge. Here we report homogeneous bilayer graphene films over at least a 2 in. × 2 in. area, synthesized by chemical vapor deposition on copper foil and subsequently transferred to arbitrary substrates. The bilayer nature of graphene film is verified by Raman spectroscopy, atomic force microscopy, and transmission electron microscopy. Importantly, spatially resolved Raman spectroscopy confirms a bilayer coverage of over 99%. The homogeneity of the film is further supported by electrical transport measurements on dual-gate bilayer graphene transistors, in which a band gap opening is observed in 98% of the devices.
Development and Validation of a Massively Parallel Flow Solver for Turbomachinery Flows

The development and validation of the unsteady, three-dimensional, multiblock, parallel turbomachinery  ow solver TFLO is presented. The unsteady Reynolds-averaged Navier–Stokes equations are solved using a cellcentered discretizationon arbitrarymultiblockmeshes. The solutionprocedure is basedon ef cient explicit Runge– Kuttamethodswith several convergenceacceleration techniques such asmultigrid,implicitresidual smoothing,and local time stepping.The solver is parallelized usingdomaindecomposition,a single programmultipledata strategy, and the message passing interface standard. Details of the communication scheme and load balancing algorithms are discussed. A general and ef cient procedure for parallel interblade row interfacing is developed. The dual-time stepping technique is used to advance unsteady computations in time. The focus is on improving the parallel ef ciency and scalability of the  ow solver, as well as on its initial validationof steady-state calculations in multiblade row environment.The result of this careful implementation is a solverwith demonstrated scalability up to 1024processors. For validationand veri cation purposes, results fromTFLO are comparedwith both existing experimental data and computational results from other computational  uid dynamics codes used in aircraft engine industry.
Characterization Of Electronic Streak Tubes Including One With Internal CCD Readout

Measuring techniques for characterizing electronic streak tubes including dynamic range and resolution are described. A particular tube with a CCD imaging device within the envelope is described.
Crystal structure of hexamethylguanidinium hexafluorosilicate hexahydrate

Abstract Single crystals of the hexamethylguanidinium hexafluorosilicate hexahydrate salt, [C(NMe2)3+]2SiF62−·6H2O, were isolated when a product, obtained by water removal from aqueous [C(NMe2)3]F in a glass vessel, was recrystallized from CH3OH. The crystal structure of this salt was determined, and the geometry of the free hexamethylguanidinium cation was calculated, showing that its observed propeller-shaped arrangement is not caused by solid state effects but is the true minimum energy structure of the free ion.
Phylogenetic methods in natural product research

Natural products researchers are increasingly employing evolutionary analyses of genes and gene products that rely on phylogenetic trees. The field of phylogenetic inference and of evolutionary analyses based on phylogenies is growing at an amazing rate, making it difficult to keep up with the latest methodologies. Here, we summarize phylogenetic applications in natural products research, and review methods and software useful for carrying out analyses inferring or using phylogenetic trees. We include an updated overview of available alignment methods and programs, as well as a selection of some useful phylogenetic analysis tools. This review covers primarily the period 2000-2009 for applications of phylogenetic methods in natural product research, and 1990-2009 for phylogenetic methods, with some references going back to the 1960s.
Chemotherapeutic Agents Subvert Tumor Immunity by Generating Agonists of Platelet-Activating Factor

Oxidative stress suppresses host immunity by generating oxidized lipid agonists of the platelet-activating factor receptor (PAF-R). Because many classical chemotherapeutic drugs induce reactive oxygen species (ROS), we investigated whether these drugs might subvert host immunity by activating PAF-R. Here we show that PAF-R agonists are produced in melanoma cells by chemotherapy that is administered in vitro, in vivo or in human subjects. Structural characterization of the PAF-R agonists induced revealed multiple oxidized glycerophosphocholines that are generated non-enzymatically. In a murine model of melanoma, chemotherapeutic administration could augment tumor growth by a PAF-R-dependent process that could be blocked by treatment with antioxidants or cyclooxygenase-2 inhibitors or by depletion of regulatory T cells. Our findings reveal how PAF-R agonists induced by chemotherapy treatment can promote treatment failure. Further, they offer new insights into how to improve the efficacy of chemotherapy by blocking its heretofore unknown impact on PAF-R activation.
Dynamic limits on planar libration-orbit coupling around an oblate primary

This paper explores the dynamic properties of the planar system of an ellipsoidal satellite in an equatorial orbit about an oblate primary. In particular, we investigate the conditions for which the satellite is bound in librational motion or when the satellite will circulate with respect to the primary. We find the existence of stable equilibrium points about which the satellite can librate, and explore both the linearized and non-linear dynamics around these points. Absolute bounds are placed on the phase space of the libration-orbit coupling through the use of zero-velocity curves that exist in the system. These zero-velocity curves are used to derive a sufficient condition for when the satellite’s libration is bound to less than $$90^{\circ }$$ . When this condition is not satisfied so that circulation of the satellite is possible, the initial conditions at zero libration angle are determined which lead to circulation of the satellite. Exact analytical conditions for circulation and the maximum libration angle are derived for the case of a small satellite in orbits of any eccentricity.
Embedded surfaces in the 3-torus

Those maps of a closed surface to the three-dimensional torus that are homotopic to embeddings are characterized. Particular attention is paid to the more involved case when the surface is nonorientable.
Radiation mitigation at the Moon by the terrestrial magnetosphere

[1] The Moon spends 25% of its orbit within the terrestrial magnetosphere. The magnetic field from the terrestrial magnetosphere can potentially provide radiation shielding from solar energetic particle events and lower energy galactic cosmic rays, which can be a significant hazard during extra-vehicle activities or during human exploration of the lunar surface. The level of shielding provided by the terrestrial magnetosphere is calculated in conjunction with 3D multi-fluid simulations of the terrestrial magnetospheres. It is shown that the level of shielding is dependent on IMF orientation and location of the lunar base. The natural terrain could be used to augment the terrestrial shielding for an equatorial lunar base. A polar lunar base would be exposed to twice as much radiation. But in both cases shielding of GeV particles is possible, with the upper range depending on the prevailing solar wind conditions.
Outer-rotor polysilicon wobble micromotors

Abstract This paper reports the development of a new class of polysilicon surface-micromachined wobble micromotors in which the rotor outer radius is exposed for mechanical coupling and the first instance of a polysilicon wobble micromotor directly driving another mechanical component. These motors are fabricated in a three-mask process which results in a flange bearing. The rotor and stator are fabricated from heavily phosphorus-doped polysilicon, while the bearing is made of an insulating material such as polyimide or silicon-rich silicon nitride. Rotor diameters of 150 to 250 μm and rotor/stator thicknesses of 3 to 5 μm are typical. The 5 μm thick micromotors with silicon nitride bearings have operated smoothly and reproducibly in room air for more than two years after release. Minimum operating voltages are 14 V, while maximum rotor speeds are 125 rpm, which is limited by our power-supply switching speed. These micromotors have gear ratios over 300 and estimated motive torques on the order of 10 −9 N m for 100 V excitations, which is over two orders of magnitude larger than previously reported motive torques for polysilicon micromotors. Mechanical coupling is demonstrated using a 500 μm diameter outer-rotor micromotor with gear teeth driving another similar motor operated as a passive gear.
Portfolio selection with mental accounts and delegation

Das et al. (2010) develop an elegant framework where an investor selects portfolios within mental accounts but ends up holding an aggregate portfolio on the mean–variance frontier. This investor directly allocates the wealth in each account among available assets. In practice, however, investors often delegate the task of allocating wealth among assets to portfolio managers who seek to beat certain benchmarks. Accordingly, we extend their framework to the case where the investor allocates the wealth in each account among portfolio managers. Our contribution is threefold. First, we provide an analytical characterization of the existence and composition of the optimal portfolios within accounts and the aggregate portfolio. Second, we present conditions under which such portfolios are not on the mean–variance frontier, and conditions under which they are. Third, we show that the aforementioned analytical characterization is also applicable within the framework of Das et al. and thus improves upon their numerical approach.
Recent advances on ultrafast X-ray spectroscopy in the chemical sciences

As an X-ray method for capturing transient structures of molecules during chemical reactions, X-ray transient absorption (XTA), or laser-initiated time-resolved X-ray absorption spectroscopy, has seen its capabilities greatly expanded over the past decade. XTA, which includes X-ray absorption near edge structure (XANES) and X-ray absorption fine structure (XAFS), has evolved beyond proof-of-concept studies and has been increasingly used to interrogate real chemical problems. Advances in ultrafast laser technology, pulsed X-ray sources in synchrotron facilities, as well as the frontier femtosecond X-ray pulses from X-ray free electron lasers have opened up new opportunities to gain a new fundamental description of the chemical sciences. This review reports historical and recent advances in XTA, particularly in its chemical applications, and is focused on (1) an overview of XTA capabilities in comparison to the related techniques of X-ray emission spectroscopy (XES) and resonant inelastic X-ray scattering (RIXS), (2) general chemical properties that can be investigated by the XTA method, (3) chemical systems studied by XTA investigations such as transition metal complexes, metalloproteins and hybrid systems, and (4) summary and perspectives.
Grain boundary sliding on near-7°, 14°, and 22° special boundaries during thermomechanical cycling in surface-mount lead-free solder joint specimens

Abstract To investigate the effect of external loads arising from differential thermal expansion between a substrate and a surface-mount component during thermomechanical cycling, specimens with a nickel surface-mount component on a copper substrate were prepared. Specimens consisted of two 100 μm thick 1 mm 2 solder joints about 9 mm apart, with two designs. In one specimen (denoted “ dual-shear ”), the as-fabricated joints were not stressed due to differential contraction during solidification and cool down. In the other specimen (denoted “ component ”), a continuous copper substrate between the joints caused the nickel component to be put in compression during cool down, which imposed shear on the joints. To impose differential thermal shear strains, the “dual-shear” specimen was clamped to a copper block to cause a significant reversal in sign of the shear imposed on the solder joint during cycling. In the “component” specimen configuration, the existing compressive strain in the component increased with cooling, but the stress was reduced with heating. Both joints were polished on the side, and then subjected to thermomechanical cycling for 3.5 h at −15 °C and 20 min at 150 °C. The effect of the two strain histories on microstructural evolution and heterogeneous straining was compared using scanning electron microscopy and orientation imaging microscopy. Each joint was made up of one to three very large grains containing low-angle boundaries and embedded minority orientations that evolved with cycling. The “component” specimen exhibited less heterogeneous strain than the “dual-shear” specimen that had reversed shear stresses. Since the dominant tin orientation was different in each joint, the resolved shear stress on various slip systems differed. In both specimens, the joint with the largest resolved shear parallel to the c -axis showed the greatest amount of heterogeneous strain arising primarily from sliding on [1 1 0] tilt boundaries misoriented by 7°, 14°, or about 20°. These boundary misorientations are close to misorientations with a coincident site lattice geometry.
Pulsar Slot Gaps and Unidentified Egret Sources

A new picture of pulsar high-energy emission is proposed that is different from both the traditional polar cap and outer gap models, but combines elements of each. The slot gap model is based on electron acceleration along the edge of the open field region from the neutron star surface to near the light cylinder and thus could form a physical basis for the two-pole caustic model of Dyks and Rudak (2003). Along the last open field line, the pair formation front rises to very high altitude forming a slot gap, where the accelerating electric field is unscreened by pairs. The resulting radiation features both hollow cones from the lower-altitude pair cascades, seen at small viewing angles, as well as caustic emission on the trailing-edge field lines at high altitude, seen from both poles at large viewing angle. The combination of the small solid angle of slot gap emission (≪1 sr) with a high probability of viewing the emission predicts that more gamma-ray pulsars could be detected at larger distances. In this picture, many of the positional coincidences of radio pulsars with unidentified EGRET sources become plausible as real associations, as the flux predicted by the slot gap model for many of the pulsars would provide the observed EGRET source flux. The expected probability of seeing radio-quiet gamma-ray pulsars in this model will also be discussed.
Cratering phenomena on aircraft anti-icing films

This article reports on a study of cratering effects in thin anti-icing films designed to protect aircraft surfaces from snow and ice accumulation while the aircraft is on the ground awaiting takeoff. These fluids primarily consist of a glycol used as a freezing point depressant, water, and to a small extent thickening and wetting agents. Craters formed in these films represent local areas where the film thickness is dramatically reduced and can lead to premature failure of the film. This phenomenon was found to be driven by surface tension gradients at the film surface that cause surface movement and drag the underlying fluid. These surface tension gradients are formed because the surfactants being used in the antiicing fluids are more effective in water-rich solutions than in glycol-rich solutions. Experimental results are given that illustrate this behavior of the surfactant and numerical work is presented to show that the magnitude of surface tension differences obtained is adequate to drive the phenomenon.
Population models with singular equilibrium

A class of models of biological population and communities with a singular equilibrium at the origin is analyzed; it is shown that these models can possess a dynamical regime of deterministic extinction, which is crucially important from the biological standpoint. This regime corresponds to the presence of a family of homoclinics to the origin, so-called elliptic sector. The complete analysis of possible topological structures in a neighborhood of the origin, as well as asymptotics to orbits tending to this point, is given. An algorithmic approach to analyze system behavior with parameter changes is presented. The developed methods and algorithm are applied to existing mathematical models of biological systems. In particular, we analyze a model of anticancer treatment with oncolytic viruses, a parasite-host interaction model, and a model of Chagas' disease.
Linear bounds on growth of associated primes

We find explicit bounds on the primary components and on the Castelnuovo-Mumford regularity of powers of monomial ideals. We also analyze the primary decompositions of Katzman's example.
The William Kruskal Legacy: 1919–2005

William Kruskal (Bill) was a distinguished statistician who spent virtually his entire professional career at the University of Chicago, and who had a lasting impact on the Institute of Mathematical Statistics and on the field of statistics more broadly, as well as on many who came in contact with him. Bill passed away last April following an extended illness, and on May 19, 2005, the University of Chicago held a memorial service at which several of Bill’s colleagues and collaborators spoke along with members of his family and other friends. This biography and the accompanying commentaries derive in part from brief presentations on that occasion, along with recollections and input from several others. Bill was known personally to most of an older generation of statisticians as an editor and as an intellectual and professional leader. In 1994, Statistical Science published an interview by Sandy Zabell (Vol. 9, 285–303) in which Bill looked back on selected events in his professional life. One of the purposes of the present biography and accompanying commentaries is to reintroduce him to old friends and to introduce him for the first time to new generations of statisticians who never had an opportunity to interact with him and to fall under his influence.
Institutions and government controls

Abstract This paper develops a model of government policy toward industrial control and regulation that sheds light on the determinants of differential country experiences in terms of organizational arrangement and enterprise performance. In contrast to the model developed by Shleifer and Vishny [Shleifer, A., Vishny, R.W., 1994. “Politicians and Firms,” Quarterly Journal of Economics, 109, 995–1025; Shleifer, A., Vishny, R.W., 1998. The Grabbing Hand: Government Pathologies and Their Cures. Harvard Univ. Press, Cambridge, MA], which suggests that government controls over firms come about when politicians can use public funds to buyoff the managers and solicit their cooperation in politically motivated redistribution of rents, the present shows that it may be the ability to use the government's regulatory powers at discretion that encourages politicians to impose controls on firms and redistribute their rents. The model implies that the politicians' appetite for intervention tends to be greater when the cost of collecting and using public funds is higher, which is the opposite of what the Shleifer–Vishny model predicts. The present model helps explain the puzzling observation that countries with poor institutions are more likely to impose extensive controls on production and maintain large and inefficient public sectors. The model also sheds light on a variety of other stylized facts and puzzles and offers new hypotheses to be tested.
Unsupervised pattern discovery in human chromatin structure through genomic segmentation

Sequence census methods like ChIP-seq now produce an unprecedented amount of genome-anchored data. We have developed an integrative method to identify patterns from multiple experiments simultaneously while taking full advantage of high-resolution data, discovering joint patterns across different assay types. We apply this method to ENCODE chromatin data for the human chronic myeloid leukemia cell line K562, including ChIP-seq data on covalent histone modifications and transcription factor binding, and DNase-seq and FAIRE-seq readouts of open chromatin. In an unsupervised fashion, we identify patterns associated with transcription start sites, gene ends, enhancers, CTCF elements, and repressed regions. The method yields a model which elucidates the relationship between assay observations and functional elements in the genome. This model identifies sequences likely to affect transcription, and we verify these predictions in laboratory experiments. We have made software and an integrative genome browser track freely available (noble.gs.washington.edu/proj/segway/).
Synthesis Of Materials With Infrared And Ultraviolet Lasers

This paper discusses three divergent examples of synthesis of materials with lasers. The three techniques are: (1) infrared (CO/sub 2/) laser synthesis of silane (SiH/sub 4/) from disilane (Si/sub 2/H/sub 6/); (2) excimer (ArF) laser production of fine silicon powders from methyl- and chloro-substituted silanes; and, (3) excimer (KrF) laser production of fine metallic powders by laser ablation. The mechanism for each process is discussed along with some conclusions about the features of the laser radiation that enable each application. 19 refs., 12 figs., 2 tabs.
Codinaeopsin, an Antimalarial Fungal Polyketide

A new tryptophan−polyketide hybrid, codinaeopsin, was isolated from an endophytic fungus collected in Costa Rica. The structure of codinaeopsin, which was deduced from NMR and mass spectral data, contains an unusual heterocyclic unit linking indole and decalin fragments. Codinaeopsin is active against Plasmodium falciparum, the causative agent of the most lethal form of malaria (IC50 = 2.3 μg/mL or 4.7 μM).
Debt and the marginal tax rate

Abstract Do taxes affect corporate debt policy? This paper tests whether the incremental use of debt is positively related to simulated firm-specific marginal tax rates that account for net operating losses, investment tax credits, and the alternative minimum tax. The simulated marginal tax rates exhibit substantial variation due to the dynamics of the tax code, tax regime shifts, business cycle effects, and the progressive nature of the statutory tax schedule. Using annual data from more than 10,000 firms for the years 1980–1992, I provide evidence which indicates that high-tax-rate firms issue more debt than their low-tax-rate counterparts.
STELLAR COMPANIONS TO STARS WITH PLANETS

A combination of high-resolution and wide-field imaging reveals two binary stars and one triple star system among the sample of the first 11 stars with planets detected by radial velocity variations. High-resolution speckle or adaptive optics (AO) data probe subarcsecond scales down to the diffraction limit of the Keck 10 m or the Lick 3 m, and direct images or AO images are sensitive to a wider field, extending to 10'' or 38'', depending on the camera. One of the binary system—HD 114762—was not previously known to be a spatially resolved multiple system; additional data taken with the combination of Keck adaptive optics and NIRSPEC are used to characterize the new companion. The second binary system—τ Boo—was a known multiple with two conflicting orbital solutions; the current data will help constrain the discrepant estimates of periastron time and separation. Another target—16 Cyg B—was a known common proper motion binary, but the current data resolve a new third component, close to the wide companion 16 Cyg A. Both the HD 114762 and 16 Cyg B systems harbor planets in eccentric orbits, while the τ Boo binary contains an extremely close planet in a tidally circularized orbit. Although the sample is currently small, the proportion of binary systems is comparable to that measured in the field over a similar separation range. Incorporating the null result from another companion search project lowers the overall fraction of planets in binary systems, but the detections in our survey reveal that planets can form in binaries separated by less than 50 AU.
On First-Order Decoupling of Equations of Motion for Constrained Dynamical Systems

In this paper we present a method for obtaining first-order decoupled equations of motion for multirigid body systems. The inherent flexibility in choosing generalized velocity components as a function of generalized coordinates is used to influence the structure of the resulting dynamical equations. Initially, we describe how a congruency transformation can be formed that represents the transformation between generalized velocity components and generalized coordinate derivatives. It is shown that the proper choice for the congruency transformation will insure generation of first-order decoupled equations of motion for holonomic systems. In the case of nonholonomic systems, or holonomic systems with unreduced configuration coordinates, we incorporate an orthogonal complement in conjunction with the congruency transformation. A pair of examples illustrate the results. Finally, we discuss numerical implementation of congruency transformations to achieve first-order decoupled equations for simulation purposes. Introduction
SOURCE ELLIPTICITY AND THE STATISTICS OF LENSED ARCS

The statistics of gravitationally lensed arcs, which can be used for a variety of cosmological tests, are sensitive to the intrinsic shapes of the source galaxies. I present an analytic formalism that makes it simple to include elliptical sources in analytic calculations of lens statistics. For cuspy lens models, sources with an axis ratio of 2:1 enhance the total number of arcs longer than 10:1 by a factor of order 2, while modestly decreasing the number ratio of radial arcs to tangential arcs. Source ellipticity is therefore an important systematic effect in detailed quantitative studies, but it should not hinder cosmological applications such as attempts to constrain cluster dark matter profiles with arc statistics.
Implications of driving style and road grade for accurate vehicle activity data and emissions estimates

Abstract Real-world vehicle operating mode data (2.5 million 1 Hz records), collected by instrumenting the vehicles of 82 volunteer drivers with OBD datalogger and GPS while they drove their routine travel routes, were analyzed to quantify vehicle emissions estimate errors due to road grade and driving style in rural, hilly Vermont. Data were collected in winter and summer for MY 1996 and newer passenger cars and trucks only. EPA MOVES2010b was used to estimate running exhaust emissions associated with measured vehicle activity. Changes in vehicle specific power (VSP) and MOVES operating mode (OpMode) due to proper accounting for real-world road grade indicated emission rate errors between 10% and 48%, depending on pollutant, chiefly because grade-related changes in VSP could shift activity by as many as six OpModes, depending on road type. The correct MOVES OpMode assignment was made only 33–55% of the time when road grade was not included in the VSP calculation. Driving style of individual drivers was difficult to assess due to unknown traffic operations data, but the largest differences between individual drivers were observed on rural restricted roads, where traffic conditions and control have minimal impact. The results suggest the importance of (1) measuring and incorporating real-world road grade in order to correctly assign MOVES emission rates; and (2) developing a driving style typology to account for differences in the MOVES emissions estimates due to driver variability.
Far Ultraviolet Spectroscopic Explorer Observations of a Supernova Remnant in the Line of Sight to HD 5980 in the Small Magellanic Cloud

We report a detection of far-ultraviolet absorption from the supernova remnant SNR 0057-7226 in the Small Magellanic Cloud (SMC). The absorption is seen in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of the luminous blue variable/Wolf-Rayet star HD 5980. Absorption from O VI λ1032 and C III λ977 is seen at a velocity of 300 km s-1 with respect to the Galactic absorption lines, 170 km s-1 with respect to the SMC absorption. The O VI λ1038 line is contaminated by H2 absorption but is present. These lines are not seen in the FUSE spectrum of Sk 80, only ~1' (~17 pc) away from HD 5980. No blueshifted O VI λ1032 absorption from the SNR is seen in the FUSE spectrum. The O VI λ1032 line in the SNR is well described by a Gaussian with FWHM = 75 km s-1. We find log N(O ) = 14.33-14.43, which is roughly 50% of the rest of the O VI column in the SMC (excluding the SNR) and greater than the O VI column in the Milky Way halo along this sight line. The N(C IV)/N(O VI) ratio for the SNR absorption is in the range of 0.12-0.17, similar to the value seen in the Milky Way disk and lower than the halo value, supporting models in which SNRs produce the highly ionized gas close to the plane of the Galaxy, while other mechanisms occur in the halo. The N(C IV)/N(O VI) ratio is also lower than the SMC ratio along this sight line, suggesting that other mechanisms contribute to the creation of the global hot ionized medium in the SMC. The O VI, C IV, and Si IV apparent column density profiles suggest the presence of a multiphase shell followed by a region of higher temperature gas.
Power allocation and spectrum sharing in multi-user, multi-channel systems with strategic users

We consider the decentralized power allocation and spectrum sharing problem in multi-user, multi-channel systems with strategic users. We present a mechanism/game form that has the following desirable features: 1) it is individually rational; 2) it is budget balanced at every Nash equilibrium of the game induced by the game form as well as off equilibrium; and 3) the allocation corresponding to every Nash equilibrium (NE) of the game induced by the mechanism is a Lindahl allocation, that is, a weakly Pareto optimal allocation; conversely, every Lindahl equilibrium results in a NE of the game induced by the game form. Our proposed game form/mechanism achieves all the above desirable properties without any assumption about, concavity, monotonicity, or quasi-linearity of the users' utility functions.
Material characterization of in vivo and in vitro porcine brain using shear wave elasticity.

Abstract Realistic computer simulation of closed head trauma requires accurate mechanical properties of brain tissue, ideally in vivo. A substantive deficiency of most existing experimental brain data is that properties were identified through in vitro mechanical testing. This study develops a novel application of shear wave elasticity imaging to assess porcine brain tissue shear modulus in vivo. Shear wave elasticity imaging is a quantitative ultrasound technique that has been used here to examine changes in brain tissue shear modulus as a function of several experimental and physiologic parameters. Animal studies were performed using two different ultrasound transducers to explore the differences in physical response between closed skull and open skull arrangements. In vivo intracranial pressure in four animals was varied over a relevant physiologic range (2–40 mmHg) and was correlated with shear wave speed and stiffness estimates in brain tissue. We found that stiffness does not vary with modulation of intracranial pressure. Additional in vitro porcine specimens (n = 14) were used to investigate variation in brain tissue stiffness with temperature, confinement, spatial location and transducer orientation. We observed a statistically significant decrease in stiffness with increased temperature (23%) and an increase in stiffness with decreasing external confinement (22–37%). This study determined the feasibility of using shear wave elasticity imaging to characterize porcine brain tissue both in vitro and in vivo. Our results underline the importance of temperature- and skull-derived boundary conditions to brain stiffness and suggest that physiologic ranges of intracranial pressure do not significantly affect in situ brain tissue properties. Shear wave elasticity imaging allowed for brain material properties to be experimentally characterized in a physiologic setting and provides a stronger basis for assessing brain injury in computational models.
Male Influences on Cervical Cancer Risk

Risk factors for squamous cell carcinoma of the uterine cervix were studied among low income, married Hispanic women and their husbands, using a case-control design. A total of 45 eligible cases were identified at public hospitals and community clinics in the San Francisco Bay Area. For each case, a control was selected within two years of age from among Hispanic women seen at the same institution. Thirty-nine matched pairs of couples were interviewed to assess histories of sexual behavior and other possible risk factors. Cases and controls differed markedly in the number of past sexual partners of their husbands. Cases were 5.3 times more likely to be married to husbands who had had 20 or more sexual partners than were controls. Cases and controls themselves did not differ in their number of sexual partners, but cases were younger at first intercourse than were controls. The association with husband's sexual history persisted after adjusting for the woman's number of sexual partners or age at first intercourse. These results support the infectious and venereal transmission of cervical cancer and indicate the important role of husbands in its occurrence in a population with high incidence rates.
Toward a Universal Water Model: First Principles Simulations from the Dimer to the Liquid Phase

A full-dimensional model of water, HBB2-pol, derived entirely from "first-principles", is introduced and employed in computer simulations ranging from the dimer to the liquid. HBB2-pol provides excellent agreement with the measured second and third virial coefficients and, by construction, reproduces the dimer vibration-rotation-tunneling spectrum. The model also predicts the relative energy differences between isomers of small water clusters within the accuracy of highly correlated electronic structure methods. Importantly, when combined with simulation methods that explicitly include zero-point energy and quantum thermal motion, HBB2-pol accurately describes both structural and dynamical properties of the liquid phase.
NIF laser line-replaceable units (LRUs)

The National Ignition Facility (NIF) is designed with its high-value optical systems in cassettes called line-replaceable Units (LRUs). Virtually all of NIF's active components are assembled in one of approximately 4000 electrical and optical LRUs that serve between two and eight of NIF's 192 laser beamlines. Many of these LRUs are optomechanical assemblies that are roughly the size of a telephone booth. The primary design challenges for this hardware include meeting stringent mechanical precision, stability, and cleanliness requirements. Pre-production units of each LRU type have been fielded on the first bundle of NIF and have been used to demonstrate that NIF meets its performance objectives. This presentation provides an overview of NIF LRUs-and their design and production plans for building out the remaining NIF bundles.
Cascade production from antikaon induced reactions on lambda and sigma

Abstract Using a gauged flavor SU(3)-invariant hadronic Lagrangian, we study Ξ production from K induced reactions on Λ and Σ in a coupled-channel approach. Including the four channels of K Λ , K Σ , πΞ , and ηΞ , we solve the Bethe–Salpeter equation in the K -matrix approximation by neglecting the off-shell contribution in the intermediate states. For the transition potential which drives the higher-order contribution, we consider all allowed Born diagrams in the s , t , and u channels. With coupling constants determined from the SU(3) symmetry using empirical input, we find that the cross sections for the reactions K Λ→πΞ , K Σ→πΞ , K Λ→ηΞ , and K Σ→ηΞ all have values of a few mb. In contrast to the results from the lowest-order Born approximation, the magnitude of these cross sections is less sensitive to the values of the cut-off parameters in the form factors. From the transition matrix in the coupled-channel approach, we have further evaluated the cross sections for the elastic process K Λ→ K Λ , K Σ→ K Σ , πΞ→πΞ , and ηΞ→ηΞ as well as for the inelastic processes K Λ→ K Σ and πΞ→ηΞ . Implications of the reactions studied here in Ξ production from relativistic heavy ion collisions are discussed.
Effect of the Mott cross section on charge identification in the HEAO-3 heavy cosmic ray experiment

Corrections to the Z-squared dependence of ion chamber and Cherenkov response due to the Mott cross section are calculated for the HEAO-3 Heavy Cosmic Ray Experiment. The effect of the production and escape of high energy secondary electrons on detector response is accounted for by numerical calculations. These secondary electron effects are shown to influence the size of the non Z-squared effects and thus affect the charge assignments and detector resolution. The Bloch and relativistic Bloch corrections are not included in the results presented here but may be combined with the Mott corrections when the Bloch corrections are properly evaluated.
Improving effective bandwidth through compiler enhancement of global cache reuse

The performance of modern machines is increasingly limited by insufficient memory bandwidth. One way to alleviate this bandwidth limitation for a given program is to minimize the aggregate data volume the program transfers from memory. In this article we present compiler strategies for accomplishing this minimization. Following a discussion of the underlying causes of bandwidth limitations, we present a two-step strategy to exploit global cache reuse--the temporal reuse across the whole program and the spatial reuse across the entire data set used in that program. In the first step, we fuse computation on the same data using a technique called reuse-based loop fusion to integrate loops with different control structures. We prove that optimal fusion for bandwidth is NP-hard and we explore the limitations of computation fusion using perfect program information. In the second step, we group data used by the same computation through the technique of affinity-based data regrouping, which intermixes the storage assignments of program data elements at different granularities. We show that the method is compile-time optimal and can be used on array and structure data. We prove that two extensions--partial and dynamic data regrouping--are NP-hard problems. Finally, we describe our compiler implementation and experiments demonstrating that the new global strategy, on average, reduces memory traffic by over 40% and improves execution speed by over 60% on two high-end workstations.