cssi/SciSciGPT-SciSciNet huggingface dataset:
Quark-hadron phase transitions in Young and old neutron stars

Abstract The mixed phase of quarks and hadrons which might exist in the dense matter encountered in the varying conditions of temperature and trapped neutrino fraction in proto-neutron stars is studied. We show that hadronic equations of state that maximize the quark content of matter at a given density generally minimize the extent of the mixed phase region in a neutron star of a given mass, and that only in extreme cases could a pure quark star result. Neutrino trapping inhibits the appearance of a mixed phase which leads to possible proto-neutron star metastability. We also demonstrate that the temperature along adiabats in the quark-hadron mixed phase is much smaller than what is found for the kaon condensate-hadron mixed phase. This could lead to core temperatures which are significantly lower in stars containing quarks than in those not containing quarks.
Stability of user-equilibrium route flow solutions for the traffic assignment problem

This paper studies stability of user-equilibrium (UE) route flow solutions with respect to inputs to a traffic assignment problem, namely the travel demand and parameters in the link cost function. It shows, under certain continuity and strict monotonicity assumptions on the link cost function, that the UE link flow is a continuous function of the inputs, that the set of UE route flows is a continuous multifunction of the inputs, and that the UE route flow selected to maximize an objective function with certain properties is a continuous function of the inputs. The maximum entropy UE route flow is an example of the last. On the other hand, a UE route flow arbitrarily generated in a standard traffic assignment procedure may not bear such continuity property, as demonstrated by an example in this paper.
Ring cusp discharge chamber performance optimization

An experimental study of the effects of discharge chamber length and the locations of the anode, cathode and ring cusp within the chamber on the performance of an 8 cm dia. ring cusp thruster is described. As these lengths and positions are varied the changes induced in plasma ion energy costs, extracted ion fractions and ion beam profiles are measured. Results show that the anode may be positioned at any location along an 'optimum virtual anode' magnetic field line and minimum plasma ion energy costs will result. The actual location of this field line is related to a 'virtual cathode' magnetic field line that is defined by the cathode position. The magnetic field has to be such that the virtual anode field line intersects the grids at the outermost ring of grid holes to maximize the extracted ion fraction and flatten the ion beam profile. Discharge chamber lengths that were as small as possible in the test apparatus yielded the lowest extracted ion fractions.
Electronic structure of self-assembled quantum dots: comparison between density functional theory and diffusion quantum Monte Carlo

Abstract We have calculated the exchange, correlation, and total electronic energy of a realistic InAs self-assembled quantum dot embedded in a GaAs matrix as a function of the number of electrons in the dot. The many-body interactions have been treated using the local spin density approximation (LSDA) to density functional theory (DFT) and diffusion quantum Monte Carlo (DMC), so that we may quantify the error introduced by LSDA. The comparison shows that the LSDA errors are about 1–2 meV per electron for the system considered. These errors are small enough to justify the use of LSDA calculations to test models of self-assembled dots against current experimental measurements.
Estimating local prevalence of mental health problems

I present an improved methodology for estimating local prevalence rates using classical econometric methods. I provide information on the variation within national mental health surveys associated with ICD versus DSM coding. Conditional on the validity of national survey responses, I estimate precise and statistically significant models associated with binary measures of mental health diagnoses. I also present estimates from polychotomous discrete choice allowing for covariance in errors. Focusing on binary discrete measures, empirical results from NCS-R and NSADMHP are qualitatively similar though very different from NHIS. I speculate that, to a significant degree, this occurs because both NCS-R and NSADMHP rely on popular screening tools to mechanically diagnosis sample participants, while NHIS relies on self-diagnosis. I also discuss the effects on local prevalence estimates caused by unobserved community-specific effects. Finally, I use the results to make policy statements about the provision of public mental health services in central Virginia; the results document a severe shortage of services for people who are unlikely to be able to afford services in the private market.
Automatic Verification of Fault-Tolerant Register Emulations

The design and verification of fault-tolerant distributed algorithms is a complicated task. Usually, the proof of correctness is done manually, and thus depends on the skill of the prover. Using automated verification methods, such as model checking, can greatly simplify the verification. However, model checking of distributed algorithms is often intractable because of the state-explosion problem. In this paper we present a novel approach to verification of quorum-based distributed register emulation algorithms with undetectable crash failures of processes. Our approach is based on projection and abstraction and allows us to reduce the task of model-checking the whole system to fair model-checking of subsystems consisting of a constant number of processes. Our method is highly scalable and can be applied to a large class of algorithms. Aside from efficient verification, it can also be used for finding redundancies in existing algorithms.
Thioaldehydes in cycloaddition reactions: synthesis of nuclear analogues of pyrazolidinone antibacterial agents

Abstract In situ generated thioaldehydes have been found to undergo 1,3-dipolar cycloadditions with a pyrazolidinium ylide to produce a nuclear analogue of pyrazolidinone antibacterial agents.
Thermodynamics of free domain wall and overlap fermions

Abstract Studies of non-interacting lattice fermions give an estimate of the size of discretization errors and finite size effects for more interesting problems like finite temperature QCD. We present a calculation of the thermodynamic equation of state for free domain wall and overlap fermions.
Fibrations on four-folds with trivial canonical bundles

Four-folds with trivial canonical bundles are divided into six classes according to their holonomy group. We consider examples that are fibred by abelian surfaces over the projective plane. We construct such fibrations in five of the six classes, and prove that there is no such fibration in the sixth class. We classify all such fibrations whose generic fibre is the Jacobian of a genus two curve.
Nano-subgrain strengthening in ball-milled iron

Abstract The strength and deformation behavior of ball-milled, iron-base materials containing nano-scale subgrains have been evaluated. As reported by several authors, nano-subgrains form during the early stages of ball milling as a result of severe plastic deformation inherent in the ball milling process. The strength for these nano-scale subgrains are compared with the strength of larger-scale subgrains in iron and iron-base alloys produced by traditional mechanical working. The data covers over two orders of magnitude in subgrain size (from 30 nm to 6 μm) and shows a continuous pattern of behavior. For all materials studied, the strength varied as λ −1 , where λ is the subgrain size. Strengthening from subgrains was found to breakdown at a much smaller subgrain size than strengthening from grains. In addition, the ball-milled materials showed significant strengthening contributions from nano-scale oxide particles. Shear bands are developed during compression testing of ball-milled materials containing ultra-fine subgrains. A model for shear band development in nano-scale subgrains during deformation has also been developed. The model predicts a strain state of uniaxial compression in the shear band with a strain of −1.24. Subgrains are shown to offer the opportunity for high strength and good work hardening with the absence of yield point behavior.
RI-MINACE FILTERS TO AUGMENT SEGMENTATION OF TOUCHING OBJECTS

Abstract RI-MINACE filters are described for a rotation-invariant distortion-invariant multi-object detection problem. The objects are agricultural products, pistachio nuts, and the sensor is X-ray. The nuts can have any orientation hence rotation invariance is necessary. Distortion invariance is needed because each nut varies in size and shape. To detect the separate correlation peaks, we use peaksorting with a window and minimum threshold. Design issues that arise in this application include: use of gray scale or binary images; the circular harmonic function order to use; selection of the reference object, the size of the filter, the MINACE control parameter c , and the peaksorting parameters.
Saturation of the Magnetothermal Instability in Three Dimensions

In dilute astrophysical plasmas, thermal conduction is primarily along magnetic field lines, and therefore highly anisotropic. As a result, the usual convective stability criterion is modified from a condition on entropy to a condition on temperature. For small magnetic fields or small wavenumbers, instability occurs in any atmosphere where the temperature and pressure gradients point in the same direction. We refer to the resulting convective instability as the magnetothermal instability (MTI). We present fully three-dimensional simulations of the MTI and show that saturation results in an atmosphere with different vertical structure, dependent on the boundary conditions. When the temperature at the boundary of the unstable layer is allowed to vary, the temperature gradient relaxes until the unstable region is almost isothermal. When the temperature at the boundary of the unstable region is fixed, the magnetic field is reoriented to an almost vertical geometry as a result of buoyant motions. This case exhibits more vigorous turbulence. In both cases the resulting saturated heat flux is almost one-half of the value expected if the conduction were purely isotropic, ~ ??T/L, where ? is the thermal conductivity, ?T is the fixed temperature drop across the simulation domain, and L is the temperature gradient scale length. The action of the MTI results in dynamical processes that lead to significant transport perpendicular to the initial direction of the magnetic field. The resulting magnetoconvection in both cases amplifies the magnetic field until it is almost in equipartition with sustained subsonic turbulence. These results are relevant to understanding measurements of the temperature profiles of the intracluster medium of clusters of galaxies as well as the structure of radiatively inefficient accretion flows.
Business groups, the financial market and modernization*

Business groups are an important aspect of the industrial organization of many developing countries. This paper develops a theory suggesting that they may be organizations that facilitate modernization in the presence of financial market constraints. An important function of the stockmarket is the diversification of risk that comes with specialized, productive technology. But in the face of serious information problems a well functioning stockmarket may fail to emerge, relegating the economy to a low productivity-poverty trap. Bilateral links between a firm and a group of others may be a more cost effective way to achieve risk-sharing. Such business groups may be feasible when a full-fledged stockmarket is not. As modernization takes place, either because information problems become less severe or more firms enter the economy, business groups actually expand in size before being abruptly rendered obsolete by the stockmarket. This is consistent with empirical results from a number of emerging economies.
Adaptive Methods for Linear Programming Decoding

Detectability of failures of linear programming (LP) decoding and the potential for improvement by adding new constraints motivate the use of an adaptive approach in selecting the constraints for the underlying LP problem. In this paper, we make a first step in studying this method, and show that by starting from a simple LP problem and adaptively adding the necessary constraints, the complexity of LP decoding can be significantly reduced. In particular, we observe that with adaptive LP decoding, the sizes of the LP problems that need to be solved become practically independent of the density of the parity-check matrix. We further show that adaptively adding extra constraints, such as constraints based on redundant parity checks, can provide large gains in the performance.
Indirect mass spectrometric methods for characterizing and sequencing oligonucleotides.

The use of mass spectrometry for the characterization and sequence determination of oligonucleotides is reviewed. This review focuses primarily on the use of mass spectrometry to analyze sequence-specific fragments of oligonucleotides that are generated via solution-phase chemical reactions. The majority of these "indirect" sequencing methods are a result of recent advances in electrospray ionization and matrix-assisted laser desorption/ionization for the generation of intact gas-phase ions from oligonucleotides. Descriptions of the current indirect sequencing protocols will be presented as well as a comparison of the applicability of these procedures for analyzing "real world" samples. The applicability of indirect mass spectrometric sequencing to antisense oligonucleotides will be discussed in detail. AÂ© 1997 John Wiley & Sons, Inc.
THE LONG-TERM EVOLUTION OF DOUBLE WHITE DWARF MERGERS

In this paper, we present a model for the long-term evolution of the merger of two unequal mass C/O white dwarfs (WDs). After the dynamical phase of the merger, magnetic stresses rapidly redistribute angular momentum, leading to nearly solid-body rotation on a viscous timescale of 10{sup -4}-1 yr, long before significant cooling can occur. Due to heating during the dynamical and viscous phases, the less massive WD is transformed into a hot, slowly rotating, and radially extended envelope supported by thermal pressure. Following the viscous phase of evolution, the maximum temperature near the envelope base may already be high enough to begin off-center convective carbon burning. If not, Kelvin-Helmholtz contraction of the inner region of the envelope on a thermal timescale of 10{sup 3}-10{sup 4} yr compresses the base of the envelope, again yielding off-center burning. As a result, the long-term evolution of the merger remnant is similar to that seen in previous calculations: the burning shell diffuses inward over {approx}10{sup 4} yr, eventually yielding a high-mass O/Ne WD or a collapse to a neutron star, rather than a Type Ia supernova. During the cooling and shell-burning phases, the merger remnant radiates near the Eddington limit. Given the double WDmore » merger rate of a few per 1000 yr, a few dozen of these {approx}10{sup 38} erg s{sup -1} sources should exist in a Milky Way type galaxy. While the end result is similar to that of previous studies, the physical picture and the dynamical state of the matter in our model differ from previous work. Furthermore, substantial remaining uncertainties related to the convective structure near the photosphere and mass loss during the thermal evolution may significantly affect our conclusions. Thus, future work within the context of the physical model presented here is required to better address the eventual fate of double WD mergers, including those for which one or both of the components is a He WD.« less
Synthesis and solid state structure of an unsymmetrical triurea

Abstract The synthesis and single crystal X-ray diffraction analysis of 1 is reported. Hydrogen bonding and solvation play an important role in the solid state structure of 1 .
Who Contributes to the Knowledge Sharing Economy

Information sharing dynamics of social networks rely on a small set of influencers to effectively reach a large audience. Our recent results and observations demonstrate that the shape and identity of this elite, especially those contributing original content, is difficult to predict. Information acquisition is often cited as an example of a public good. However, this emerging and powerful theory has yet to provably offer qualitative insights on how specialization of users into active and passive participants occurs. This paper bridges, for the first time, the theory of public goods and the analysis of diffusion in social media. We introduce a non-linear model of perishable public goods, leveraging new observations about sharing of media sources. The primary contribution of this work is to show that shelf time, which characterizes the rate at which content get renewed, is a critical factor in audience participation. Our model proves a fundamental dichotomy in information diffusion: While short-lived content has simple and predictable diffusion, long-lived content has complex specialization. This occurs even when all information seekers are ex ante identical and could be a contributing factor to the difficulty of predicting social network participation and evolution.
Photoevaporation of Clumps in Photodissociation Regions

We present the results of an investigation of the effects of Far Ultraviolet (FUV) radiation (6.0eV < hv < 13.6eV) from hot early type OB stars on clumps in star-forming molecular clouds. Clumps in FUV-illuminated regions (or photodissociation regions or PDRs) undergo external heating and photodissociation as they are exposed to the FUV field, resulting in a loss of cold, molecular lump mass as it is converted to warm atomic gas. The heating, if rapid, creates strong photoevaporative mass flows off the clump surfaces, and drives shocks into the clumps, compressing them to high densities. The clumps lose mass on relatively short timescales. The evolution of an individual clump is found to be sensitive to three dimensionless parameters: Nc0, the ratio of the initial column density of the clump to the column N(0) approx. 10(exp 21) cm(exp -2) of a warm FUV-heated surface region; upsilon, the ratio of the sound speed in the heated surface to that in the cold clump material: and t(FUV)t(c), the ratio of the "turn-on time" t(FUV) of the heating flux on a clump to its initial sound crossing-time t(c). The evolution also depends on whether a confining interclump medium exists, or whether the interclump region has negligible pressure, as is the case for turbulence-generated clumps. In this paper, we use spherical 1-D numerical hydrodynamic models as well as approximate analytical models to study the dependence of clump photoevaporation on the physical parameters of the clump, and to derive the dynamical evolution, mass loss rates and photoevaporative timescales of a clump for a variety of astrophysical situations. Turbulent clumps evolve so that their column densities are equal to a critical value determined by the local FUV field, and typically have short photo evaporation timescales, approx. 10(exp 4-5) years for a 1 M(solar mass) clump in a typical star-forming region (Nc0 = 10, upsilon = 10). Clumps with insufficient magnetic pressure support, and in strong FUV fields may be driven to collapse by the compressional effect of converging shock waves. We also estimate the rocket effect on photoevaporating clumps and find that it is significant only for the smallest clumps, with sizes much less than the extent of the PDR itself. Clumps that are confined by all interclump medium may either get completely photoevaporated, or may preserve a shielded core with a warm, dissociated, protective shell that, absorbs the incident FUV flux. We compare our results with observations of some well studied PDRs: the Orion Bar, M17SW NGC 2023 and the Rosette Nebula. The data are consistent with both interpretations of clump origin. turbulence and pressure confinement, with a slight indication for favouring the turbulent model for clumps over pressure-confined
The Welfare Consequences of Irrational Exuberance: Stock Market Booms, Research Investment, and Productivity ⁄

Abstract This paper studies the effects of stock market valuation on research investment, the rate of innovation, and welfare. In the presence of financing constraints for R&D investment, episodes of high market valuation can ease these constraints and raise the economy-wide investment in R&D and the rate of innovation. If the decentralized equilibrium rate of innovation is inefficiently low, then such episodes may lead to an increase in aggregate welfare even if the higher valuation is not entirely justified by fundamentals. We present a Schumpeterian-style growth model with a costly financial intermediation process to characterize the relationship between market value, entry of new firms, and the aggregate rate of innovation. We use the model to measure the welfare consequences of a stock market run-up that may only partly be justified by fundamentals. In particular, we apply the model to the US economy in the 1990s and calibrate the impact of the NASDAQ boom on the rate of innovation, growth and welfare. The welfare effect depends on the underlying change in fundamentals. We find that with an acceleration in US trend productivity growth from a pre-1995 rate of 1.4% to a rate of 2.0% per annum, the NASDAQ boom will have resulted in a net welfare gain of 0.55%. If the new growth rate is as high as 3%, the net gain was 1.35% of the present discounted value of consumption.
A Jupiter Orbiter mother/daughter spacecraft concept

The feasibility of a tandem launch of a mother/daughter spacecraft pair with a single launch vehicle for a 1981 Mariner Jupiter Orbiter mission is described. The mother is a close derivative of the three-axis stabilized Mariner Jupiter Saturn 1977 spacecraft with the addition of a Viking-type propulsion module for orbit capture; it concentrates on the planetology and satellite science objectives. The daughter is a small, simple spin-stabilized spacecraft taking advantage of the mother's transit and delivery capabilities; it obtains in-situ measurements of the surrounding planetary environment. A conceptual design of the daughter spacecraft is presented.
Why decoherence has not solved the measurement problem: A Response to P. W. Anderson

Abstract We discuss why, contrary to claims recently made by P.W. Anderson, decoherence has not solved the quantum measurement problem.
Act global, but think local: accountability at the frontlines

Abstract There is a worrying divergence between the way that sexual and reproductive health and rights problems and solutions are framed in advocacy at the global level and the complex reality that people experience in health services on the ground. An analysis of approaches to accountability used in advocacy at these different levels highlights the different assumptions at play as to how change happens. This paper makes the case for a reinvigorated approach to accountability that begins with the dynamics of power at the frontlines, where people encounter health providers and institutions. Conventional approaches to accountability avoid grappling with these dynamics, and as a result, many accountability efforts do not lead to transformative change. Implementation science and systems science are promising sources for fresh approaches, beginning with the understanding of health systems as complex adaptive systems embedded in the broader political dynamics of their societies. By drawing insights from disciplines such as political economy, ethnography, and organizational change management – and applying them creatively to the experience of people in health systems – the workings of power can begin to be uncovered and tackled, sharpening accountability towards those whose health and rights are at stake and generating meaningful change.
Sedimentary iron records from the Cape Basin

Abstract The “Iron Hypothesis” suggests that dust-derived Fe delivered to the Southern Ocean during glacial intervals fueled primary productivity and led to CO 2 drawdown. Clear support for a dustier glacial atmosphere comes from ice-core records of dust concentrations. Furthermore, there is unequivocal proof from open-ocean Fe fertilization experiments that primary productivity in the modern-day Southern Ocean is limited by Fe. However, substantial hemipelagic detrital sources dilute and obscure the eolian signal. Here we present records of Fe concentrations (total and reducible) and Fe fluxes to highlight the importance of hemipelagic Fe sources to the Cape Basin. We illustrate that on average only 7% of the Fe flux to Site 1089 can be accounted for by particle settling, indicating that redistribution by bottom currents accounts for an order of magnitude more Fe than particulate scavenging processes, distribution by surface currents, or eolian deposition. We also find that on average only 7% of the Fe content is easily reducible. Furthermore, we speculate that a significant source of dissolved Fe to the bottom waters may come from re-suspended bottom sediments.
Overseas Deployment, Combat Exposure, and Well-Being in the 2010 National Survey of Veterans

Recent engagements in Iraq (OIF) and Afghanistan (OEF) raise questions about impacts on service members of overseas deployment. The 2010 National Survey of Veterans asked a broad cross section of veterans about deployment to OEF/OIF and combat exposure. Analysis of these data suggests that impacts of deployment and combat on the current socioeconomic well-being of OEF/OIF veterans may be small, but combat appears to reduce self-reported health and other nonpecuniary indicators. Among older cohorts, with clearer sorting into treatment and control groups, patterns are similar, consistent with a system that compensates for lost earnings but not necessarily other trauma.
Pinned distance sets, k-simplices, Wolff's exponent in finite fields and sum-product estimates

An analog of the Falconer distance problem in vector spaces over finite fields asks for the threshold α > 0 such that \({|\Delta(E)| \gtrsim q}\) whenever \({|E| \gtrsim q^{\alpha}}\), where \({E \subset {\mathbb {F}}_q^d}\), the d-dimensional vector space over a finite field with q elements (not necessarily prime). Here \({\Delta(E)=\{{(x_1-y_1)}^2+\dots+{(x_d-y_d)}^2: x,y \in E\}}\). Iosevich and Rudnev (Trans Am Math Soc 359(12):6127–6142, 2007) established the threshold \({\frac{d+1}{2}}\), and in Hart et al. (Trans Am Math Soc 363:3255–3275, 2011) proved that this exponent is sharp in odd dimensions. In two dimensions we improve the exponent to \({\tfrac{4}{3}}\), consistent with the corresponding exponent in Euclidean space obtained by Wolff (Int Math Res Not 10:547–567, 1999). The pinned distance set \({\Delta_y(E)=\{{(x_1-y_1)}^2+\dots+{(x_d-y_d)}^2: x\in E\}}\) for a pin \({y\in E}\) has been studied in the Euclidean setting. Peres and Schlag (Duke Math J 102:193–251, 2000) showed that if the Hausdorff dimension of a set E is greater than \({\tfrac{d+1}{2}}\), then the Lebesgue measure of Δy(E) is positive for almost every pin y. In this paper, we obtain the analogous result in the finite field setting. In addition, the same result is shown to be true for the pinned dot product set \({\Pi_y(E)=\{x\cdot y: x\in E\}}\). Under the additional assumption that the set E has Cartesian product structure we improve the pinned threshold for both distances and dot products to \({\frac{d^2}{2d-1}}\). The pinned dot product result for Cartesian products implies the following sum-product result. Let \({A\subset \mathbb F_q}\) and \({z\in \mathbb F^*_q}\). If \({|A|\geq q^{\frac{d}{2d-1}}}\) then there exists a subset \({E'\subset A\times \dots \times A=A^{d-1}}\) with \({|E'|\gtrsim |A|^{d-1}}\) such that for any \({(a_1,\dots, a_{d-1}) \in E'}\), $$ |a_1A+a_2A+\dots +a_{d-1}A+zA| > \frac{q}{2}$$ where \({a_j A=\{a_ja:a \in A\},j=1,\dots,d-1}\). A generalization of the Falconer distance problem is to determine the minimal α > 0 such that E contains a congruent copy of a positive proportion of k-simplices whenever \({|E| \gtrsim q^{\alpha}}\). Here the authors improve on known results (for k > 3) using Fourier analytic methods, showing that α may be taken to be \({\frac{d+k}{2}}\).
Serre weights for rank two unitary groups

We study the weight part of (a generalisation of) Serre’s conjecture for mod \(l\) Galois representations associated to automorphic representations on rank two unitary groups for odd primes \(l\). We propose a conjectural set of Serre weights, agreeing with all conjectures in the literature, and under a mild assumption on the image of the mod \(l\) Galois representation we are able to show that any modular representation is modular of each conjectured weight. We make no assumptions on the ramification or inertial degrees of \(l\). Our main innovations are the use of outer forms of \(\text{ GL}_2\) to avoid the parity difficulties with inner forms, and the use of the lifting techniques and “change of weight” results introduced in Barnet-Lamb et al. [J Am Math Soc 24(2):411–469, 2011; Duke Math J 161(8):1521–1580, 2012; Potential automorphy and change of weight, Preprint, 2010].
Alterations of lipid metabolism by contraceptive steroids.

Abstract Estrogen administration leads to increased fasting serum triglyceride concentrations which appears to be due primarily to increased hepatic production of triglycerides. These changes are favored by the increase in circulating insulin and growth hormone concentrations and the blunting of aminogenie glucagon secretion often observed in users of birth control pills. Nortestosterone derivatives (but not 17α-acetoxyprogesterone derivatives) counteract the hypertriglyceridemic effect of estrogens. A small group of patients react dramatically to estrogens with the development of massive hypertriglyceridemia. This latter group of patients appears to be particularly susceptible to pancreatitis and to electrocar-diographic changes compatible with coronary artery disease. The changes in serum cholesterol concentrations induced by individual contraceptive steroids appear to be opposite in direction from the changes observed in triglyceride concentrations. When changes in circulating cholesterol concentrations occur, they appear to be much smaller than those observed with the triglycerides. Estrogen administration produces changes in cholesterol and bile metabolism which favors gall stone formation. It is significant that an increased incidence of cholelithiasis has been observed in users of contraceptive steroids. Whether the modest changes in cholesterol and triglyceride metabolism have any effect on the development of atherosclerosis and coronary heart disease remains to be determined.
New cerium nitride chlorides: Ce6Cl12N2 and CeNCl

Abstract The compound CeNCl is shown to be isotypic with tetragonal BiOCl with lattice parameters a=b=4.079(2) A , c=6.837(2) A . The compound Ce 6 Cl 12 N 2 was prepared from CeCl 3 , Ce and NaN 3 in a sealed Nb tube at 750 °C. The structure of Ce 6 Cl 12 N 2 was solved by X-ray single crystal diffraction and shown to contain edge-shared, nitrogen-centered, cerium tetrahedra. The lattice parameters for Ce 6 Cl 12 N 2 were determined to be a=11.233(4) A , b=16.527(8) A , c=10.708(3) A , β=90.15° in the spacegroup P2 1 c .
Fluorous Mitsunobu reagents and reactions

Abstract A fully fluorous Mitsunobu reaction procedure is introduced. This employs both existing [(C 6 F 13 CH 2 CH 2 C 6 H 4 ) 2 PPh] and new [C 8 F 17 CH 2 CH 2 C 6 H 4 PPh 2 ] fluorous phosphines and a new fluorous azodicarboxylate (C 6 F 13 CH 2 CH 2 OC(O)NNCOOCH 2 CH 2 C 6 F 13 ). A procedure involving parallel reactions with representative nucleophiles and alcohols under typical Mitsunobu conditions in THF followed by rapid solid phase extraction (spe) over fluorous silica provides clean products in excellent yields. The fluorous fraction containing the oxidized phosphine oxide and the reduced hydrazide can be readily separated and the starting reagents can be regenerated by appropriate redox reactions in high yield for reuse.
The Shifting Engines of Medicalization

Social scientists and other analysts have written about medicalization since at least the 1970s. Most of these studies depict the medical profession, interprofessional or organizational contests, or social movements and interest groups as the prime movers toward medicalization. This article contends that changes in medicine in the past two decades are altering the medicalization process. Using several case examples, I argue that three major changes in medical knowledge and organization have engendered an important shift in the engines that drive medicalization: biotechnology (especially the pharmaceutical industry and genetics), consumers, and managed care. Doctors are still gatekeepers for medical treatment, but their role has become more subordinate in the expansion or contraction of medicalization. Medicalization is now more driven by commercial and market interests than by professional claims-makers. The definitional center of medicalization remains constant, but the availability of new pharmaceutical and potential genetic treatments are increasingly drivers for new medical categories. This requires a shift in the sociological focus examining medicalization for the twenty-first century.
Positive diagonal scaling of a nonnegative tensor to one with prescribed slice sums

Abstract In this paper we give necessary and sufficient conditions on a nonnegative tensor to be diagonally equivalent to a tensor with prescribed slice sums. These conditions are variations of Bapat-Raghavan and Franklin–Lorenz conditions.
Filtered Ends, Proper Holomorphic Mappings of Kähler Manifolds to Riemann Surfaces, and Kähler Groups

The main result of this paper is that a connected bounded geometry complete Kahler manifold which has at least 3 filtered ends admits a proper holomorphic mapping onto a Riemann surface. As an application, it is also proved that any properly ascending HNN extension with finitely generated base group, as well as Thompson’s groups V, T, and F, are not Kahler. The results and techniques also yield a different proof of the theorem of Gromov and Schoen that, for a connected compact Kahler manifold whose fundamental group admits a proper amalgamated product decomposition, some finite unramified cover admits a surjective holomorphic mapping onto a curve of genus at least 2.
Negative Urgency and Ventromedial Prefrontal Cortex Responses to Alcohol Cues: fMRI Evidence of Emotion‐Based Impulsivity

Background Recent research has highlighted the role of emotion-based impulsivity (negative and positive urgency personality traits) for alcohol use and abuse, but has yet to examine how these personality traits interact with the brain’s motivational systems. Using functional magnetic resonance imaging (fMRI), we tested if urgency traits and mood induction affected medial prefrontal responses to alcohol odors (AcO).
An information complexity approach to extended formulations

We prove an unconditional lower bound that any linear program that achieves an O(n1-e) approximation for clique has size 2Ω(ne). There has been considerable recent interest in proving unconditional lower bounds against any linear program. Fiorini et al. proved that there is no polynomial sized linear program for traveling salesman. Braun et al. proved that there is no polynomial sized O(n1/2 - e)-approximate linear program for clique. Here we prove an optimal and unconditional lower bound against linear programs for clique that matches Hastad's celebrated hardness result. Interestingly, the techniques used to prove such lower bounds have closely followed the progression of techniques used in communication complexity. Here we develop an information theoretic framework to approach these questions, and we use it to prove our main result. Also we resolve a related question: How many bits of communication are needed to get e-advantage over random guessing for disjointness? Kalyanasundaram and Schnitger proved that a protocol that gets constant advantage requires Ω(n) bits of communication. This result in conjunction with amplification implies that any protocol that gets e-advantage requires Ω(e2 n) bits of communication. Here we improve this bound to Ω(e n), which is optimal for any e > 0.
The Joint Spatial Representation of Multiple Variable Batteries Collected in Marketing Research

Abstract Marketing research studies pertaining to market segmentation, competitive market structure, and product/service positioning often involve the collection of multiple batteries of measurements from the same set of respondents (e.g., preferences, attribute ratings, demographics, proximity judgments). Various multidimensional scaling (MDS) and spatial methods have been used in the analysis of these variable batteries separately, but not much effort has been expended in attempting to relate the individually derived spatial structures. The authors propose a new latent structure MDS procedure that is devised to represent jointly the structure in multiple batteries (preferences, proximities, and brand attribute ratings) of variables collected across the same set of respondents. The authors present the technical structure of the proposed maximum likelihood–based model and conceptually compare it with other related spatial MDS models. The authors present an illustration of the procedure with respect to the...
Walking Together: A Paradigmatic Social Phenomenon

The everyday concept of a social group is approached by examining the concept of going for a walk together, an example of doing something together, or "shared action". Two analyses requiring shared personal goals are rejected, since they fail to explain how people walking together have obligations and rights to appropriate behavior, and corresponding rights of rebuke. An alternative account is proposed: those who walk together must constitute the "plural subject" of a goal (roughly, their walking alongside each other). The nature of plural subjecthood, the thesis that social groups are plural subjects, and the relation of these ideas to Rousseau's and Hobbes's, are briefly explored.
A Combinatorial Study of Multiplexes and Ordinary Polytopes

Bisztriczky defines a multiplex as a generalization of a simplex, and an ordinary polytope as a generalization of a cyclic polytope. This paper presents results concerning the combinatorics of multiplexes and ordinary polytopes. The flag vector of the multiplex is computed, and shown to equal the flag vector of a many-folded pyramid over a polygon. Multiplexes, but not other ordinary polytopes, are shown to be elementary. It is shown that all complete subgraphs of the graph of a multiplex determine faces of the multiplex. The toric h -vectors of the ordinary five-dimensional polytopes are given. Graphs of ordinary polytopes are studied. Their chromatic numbers and diameters are computed, and they are shown to be Hamiltonian.
An improved approximation ratio for the minimum latency problem

Given a tour visitingn points in a metric space, thelatency of one of these pointsp is the distance traveled in the tour before reachingp. Theminimum latency problem (MLP) asks for a tour passing throughn given points for which the total latency of then points is minimum; in effect, we are seeking the tour with minimum average “arrival time”. This problem has been studied in the operations research literature, where it has also been termed the “delivery-man problem” and the “traveling repairman problem”. The approximability of the MLP was first considered by Sahni and Gonzalez in 1976; however, unlike the classical traveling salesman problem (TSP), it is not easy to give any constant-factor approximation algorithm for the MLP. Recently, Blum et al. (A. Blum, P. Chalasani, D. Coppersimith, W. Pulleyblank, P. Raghavan, M. Sudan, Proceedings of the 26th ACM Symposium on the Theory of Computing, 1994, pp. 163–171) gave the first such algorithm, obtaining an approximation ratio of 144. In this work, we develop an algorithm which improves this ratio to 21.55; moreover, combining our algorithm with a recent result of Garg (N. Garg, Proceedings of the 37th IEEE Symposium on Foundations of Computer Science, 1996, pp. 302–309) provides an approximation ratio of 10.78. The development of our algorithm involves a number of techniques that seem to be of interest from the perspective of the TSP and its variants more generally. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.
Research by Not-for-Profit Enterprises

This paper focuses on the research behavior of nonprofit firms. In particular, we model process innovation and compare equilibrium research spending under alternate objectives to outcomes under profit-maximization. Do profit-maximizing organizations spend more on research than nonprofit firms? We find that the nonprofit research spending exceeds the profit-maximizing levels. The ranking between nonprofit firms and the social optima, however, is less clear. Policy implications are discussed.
Unexpected regioselective Heck arylation of ethyl (E)-4,4,4-trifluorocrotonate

Abstract Palladium-catalyzed Heck reactions of ethyl (E)-4,4,4-trifluorocrotonate 1 with aryl bromides 2a–f gave an unexpected α-arylated compound 4, ethyl (Z)-2-aryl-4,4,4-trifluorocrotonate, mainly rather than normal β-arylated compound 3, ethyl (Z)-3-aryl-4,4,4-trifluorocrotonate.
Defect formation and kinetics of atomic terrace merging.

Pairs of atomic scale terraces on a single crystal metal surface can be made to merge controllably under suitable conditions to yield steps of double height and width. We study the effect of various physical parameters on the formation of defects in a kinetic model of step doubling. We treat this manifestly nonequilibrium problem by mapping the model onto a 1D random sequential adsorption problem and solving this analytically. We also do simulations to check the validity of our treatment. We find that our treatment effectively captures the dynamic evolution and the final state of the surface morphology. We show that the number and nature of the defects formed is controlled by a single dimensionless parameter $q$. For $q$ close to one we show that the fraction of defects rises linearly with $ϵ\ensuremath{\equiv}1\ensuremath{-}q$ as $0.284ϵ$. We also show that one can arrive at the final state faster and with fewer defects by changing the parameter with time.
On Stationary Vacuum Solutions to the Einstein Equations

It is proved that the only geodesically complete stationary vacuum solution of the Einstein equations is the empty Minkowski space, or a quotient of it by a discrete group of isometries, generalizing a classical result of Lichnerowicz. In addition, we obtain an apriori bound on the curvature of stationary vacuum solutions away from the boundary or horizon.
Ligand-Based Virtual Screening by Novelty Detection with Self-Organizing Maps

We describe a novel method for ligand-based virtual screening, based on utilizing Self-Organizing Maps (SOM) as a novelty detection device. Novelty detection (or one-class classification) refers to the attempt of identifying patterns that do not belong to the space covered by a given data set. In ligand-based virtual screening, chemical structures perceived as novel lie outside the known activity space and can therefore be discarded from further investigation. In this context, the concept of “novel structure” refers to a compound, which is unlikely to share the activity of the query structures. Compounds not perceived as “novel” are suspected to share the activity of the query structures. Nowadays, various databases contain active structures but access to compounds which have been found to be inactive in a biological assay is limited. This work addresses this problem via novelty detection, which does not require proven inactive compounds. The structures are described by spatial autocorrelation functions w...
Synthetic Spectra of Hydrodynamic Models of Type Ia Supernovae

We present detailed non-LTE synthetic spectra of hydrodynamic supernovae (SNe) Ia models. We make no assumptions about the form of the spectrum at the inner boundary. We calculate both Chandrasekhar-mass deflagration models and sub-Chandrasekhar {open_quotes}helium detonators.{close_quotes} Gamma-ray deposition is handled in a simple, accurate manner. We have parameterized the storage of energy, which arises from the time-dependent deposition of radioactive decay energy, in a reasonable manner that spans the expected range. We find that the Chandrasekhar-mass deflagration model W7 of Nomoto, Thielemann, & Yokoi shows good agreement with the observed spectra of SN 1992A and SN 1994D, particularly in the UV, where our models are expected to be most accurate. The sub-Chandrasekhar models do not reproduce the UV deficit observed in normal SNe Ia. They do bear some resemblance to subluminous SNe Ia, but the shapes of the spectra (i.e., the colors) are opposite that of the observed ones, and the intermediate-mass element lines (such as SiII and CaII) are extremely weak, which seems to be a generic difficulty of the models. Although the sub-Chandrasekhar models have a significant helium abundance (unlike Chandrasekhar-mass models), helium lines are not prominent in the spectra near maximum light and thus do not actmore » as a spectral signature for the progenitor. {copyright} {ital 1997} {ital The American Astronomical Society}« less
Fossil Ionized Bubbles around Dead Quasars during Reionization

One of the most dramatic signatures of the reionization era may be the enormous ionized bubbles around luminous quasars (with radii reaching ~40 comoving Mpc), which may survive as "fossil" ionized regions long after their source shuts off. Here we study how the inhomogeneous intergalactic medium (IGM) evolves inside such fossils. The average recombination rate declines rapidly with time, and the brief quasar episode significantly increases the mean free path inside the fossil bubbles. As a result, even a weak ionizing background generated by galaxies inside the fossil can maintain it in a relatively highly and uniformly ionized state. For example, galaxies that would ionize 20%-30% of hydrogen in a random patch of the IGM can maintain 80%-90% ionization inside the fossil for a duration much longer than the average recombination time in the IGM. Quasar fossils at z 10 thus retain their identity for nearly a Hubble time and appear "gray," distinct from both the average IGM (which has a "Swiss cheese" ionization topology and a lower mean ionized fraction) and the fully ionized bubbles around active quasars. More distant fossils, at z 10, have a weaker galaxy-generated ionizing background and a higher gas density, so they can attain a Swiss cheese topology similar to the rest of the IGM, but with a smaller contrast between the ionized bubbles and the partially neutral regions separating them. Analogous He III fossils should exist around the epoch of He II/He III reionization at z ~ 3, although rapid recombination inside the He III fossils is more common. Our model of inhomogeneous recombination also applies to "double-reionization" models and shows that a nonmonotonic reionization history is even more unlikely than previously thought.
Optimal Regularity and Nondegeneracy of a Free Boundary Problem Related to the Fractional Laplacian

We discuss the optimal regularity and nondegeneracy of a free boundary problem related to the fractional Laplacian. This work is related to, but addresses a different problem from, recent work of Caffarelli et al. (J Eur Math Soc (JEMS) 12(5):1151–1179, 2010). A variant of the boundary Harnack inequality is also proved, where it is no longer required that the function be zero along the boundary.