cssi/SciSciGPT-SciSciNet huggingface dataset:
The anisotropic distribution of galactic satellites

We present a study of the spatial distribution of dwarf satellites (or subhalos) in galactic dark matter halos using dissipationless cosmological simulations of the concordance flat cold dark matter (CDM) model with vacuum energy. We find that subhalos are distributed anisotropically and are preferentially located along the major axes of the triaxial mass distributions of their hosts. The Kolmogorov-Smirnov probability for drawing our simulated subhalo sample from an isotropic distribution is PKS 1.5 × 10-4. An isotropic distribution of subhalos is thus not the correct null hypothesis for testing the CDM paradigm. The nearly planar distribution of observed Milky Way (MW) satellites is marginally consistent (probability 0.02) with being drawn randomly from the subhalo distribution in our simulations. Furthermore, if we select the subhalos likely to be luminous, we find a distribution that is consistent with the observed MW satellites. In fact, we show that subsamples of the subhalo population with a centrally concentrated radial distribution that is similar to that of the MW dwarfs typically exhibit a comparable degree of planarity. We explore the origin of the observed subhalo anisotropy and conclude that it is likely due to (1) the preferential accretion of satellites along filaments, often closely aligned with the major axis of the host halo, and (2) evolution of satellite orbits within the prolate, triaxial potentials typical of CDM halos. Agreement between predictions and observations requires the major axis of the outer dark matter halo of the Milky Way to be nearly perpendicular to the disk. We discuss possible observational tests of such disk-halo alignment with current large galaxy surveys.
The Road to Non-Heme Oxoferryls and Beyond †

Oxoiron(IV) species are often implicated in the catalytic cycles of oxygen-activating non-heme iron enzymes. The paucity of suitable model complexes stimulated us to fill this void, and our synthetic efforts have afforded a number of oxoiron(IV) complexes. This Account provides a chronological perspective of the observations that contributed to the generation of the first non-heme iron(IV)-oxo complexes in high yield and summarizes their salient properties to date.
Rekindling the Flame: Processes of Identity Resurrection

We build theory on the process of collective identity resurrection through a qualitative study investigating how community members reenergized a valued community identity following years of decline. Our findings suggest a recursive model of identity resurrection, in which community leaders marshal tangible resources such as money and human talent to orchestrate experiences and community members authenticate the experiences by judging them resonant with memories and existing identity symbols. This model draws attention to the role of experience and emotion in identity processes, extending theory that has tended to focus narrowly on cognitive aspects of collective identity. We discuss implications for processes of identity reproduction and resurrection in organizational settings, and for interdependencies between community and organizational identities.
Anomalous transformation in supersymmetric Yang-Mills theory

Abstract An “anomalous” supersymmetry transformation of the gaugino axial current is given in supersymmetric Yang-Mills theory. The contact term is computed to one-loop order by a gauge-invariant point-splitting procedure. We reexamine the supercurrent anomaly in this method.
Job mobility and careers in firms

Abstract This paper presents a theoretical model that combines employers learning about worker productivity, human capital acquisition, job-assignment and resolution of worker uncertainty regarding disutility of work from a job, to show how widely documented findings on both wage and promotion dynamics and turnover can be captured in a single set-up. Specifically we show how our model can capture results such as; probability of turnover decreases with labor market experience, wage changes during job changes is more in earlier periods, serial correlation in wages and probability of promotion increases in wages, amongst others.
Rigorous Justification of the Whitham Modulation Equations for the Generalized Korteweg–de Vries Equation

In this paper, we consider the spectral stability of spatially periodic traveling wave solutions of the generalized Korteweg-de Vries equation to long-wavelength perturbations. Specically, we extend the work of Bronski and Johnson by demonstrating that the homogenized system describing the mean behavior of a slow modulation (WKB) approximation of the solution correctly describes the linearized dispersion relation near zero frequency of the linearized equations about the background periodic wave. The latter has been shown by rigorous Evans function techniques to control the spectral stability near the origin, i.e. stability to slow modulations of the underlying solution. In particular, through our derivation of the WKB approximation we generalize the modulation expansion of Whitham for the KdV to a more general class of equations which admit periodic waves with nonzero mean. As a consequence, we will show that, assuming a particular non-degeneracy condition, spectral stability near the origin is equivalent with the local well-posedness of the Whitham system.
PageRank for ranking authors in co-citation networks

This paper studies how varied damping factors in the PageRank algorithm influence the ranking of authors and proposes weighted PageRank algorithms. We selected the 108 most highly cited authors in the information retrieval (IR) area from the 1970s to 2008 to form the author co-citation network. We calculated the ranks of these 108 authors based on PageRank with the damping factor ranging from 0.05 to 0.95. In order to test the relationship between different measures, we compared PageRank and weighted PageRank results with the citation ranking, h-index, and centrality measures. We found that in our author co-citation network, citation rank is highly correlated with PageRank with different damping factors and also with different weighted PageRank algorithms; citation rank and PageRank are not significantly correlated with centrality measures; and h-index rank does not significantly correlate with centrality measures but does significantly correlate with other measures. The key factors that have impact on the PageRank of authors in the author co-citation network are being co-cited with important authors. © 2009 Wiley Periodicals, Inc.
Does private school competition improve public school performance? The case of Nepal

Abstract Using data from the survey of the Ministry of Education, Nepal-2005 for school leaving certificate (SLC) exam, this paper attempts to estimate the impact of private school competition on public school performance for the case of Nepal. The study uses the number of private schools in the neighborhood as a measure of competition. The identification problem is that private school enrollment is likely to be correlated with public school performance. To address this, the study uses the existence of a motorable road within an hour's walking distance from the sample school as an instrument for number of private schools in the neighborhood. The OLS results show no significant relationship. In contrast, the IV method indicates a positive and significant impact of private school competition on public school performance, which holds true for the continuous and binary measure of private school competition.
Models of radar imaging of the ocean surface waves

A number of models which would explain ocean wave imagery taken with a synthetic aperture imaging radar are analyzed analytically and numerically. Actual radar imagery is used to support some conclusions. The models considered correspond to three sources of radar backscatter cross section modulation: tilt modulation, roughness variation, and the wave orbital velocity. The effect of the temporal changes of the surface structure, parametric interactions, and the resulting distortions are discussed.
Security for Grid services

Grid computing is concerned with the sharing and coordinated use of diverse resources in distributed "virtual organizations." The dynamic and multiinstitutional nature of these environments introduces challenging security issues that demand new technical approaches. In particular, one must deal with diverse local mechanisms, support dynamic creation of services, and enable dynamic creation of trust domains. We describe how these issues are addressed in two generations of the Globus Toolkit/spl reg/. First, we review the Globus Toolkit version 2 (GT2) approach; then we describe new approaches developed to support the Globus Toolkit version 3 (GT3) implementation of the Open Grid Services Architecture, an initiative that is recasting Grid concepts within a service-oriented framework based on Web services. GT3's security implementation uses Web services security mechanisms for credential exchange and other purposes, and introduces a tight least-privilege model that avoids the need for any privileged network service.
Turbulent Mixing of Multiple Co-Axial Gaseous Fuel Jets in a Supersonic Airstream

An experimental and analytical investigation of a strut-mounted, four-nozzle, downstream-facing, gaseous fuel-injector assembly was conducted in a Mach 4 airstream at 154 psia and 520 R. Helium was used as the injectant in order to simulate a low molecular weight fuel, and the interjet spacing (S/D) was the main parameter varied. The principal data are in the form of helium concentration profiles at seven axial stations, Mach number distributions at three axial stations, and Schlieren photographs of the flow field at different interjet spacings. An approximate analysis was developed based upon a linearization in the Von Mises plane, Crocco integrals for the temperature and concentrations fields, and an eddy viscosity model. Good agreement with the data was achieved. It was found that, at these conditions, interjet spacing has a significant effect on mixing only up to S/D of approximately 2.5, with the concentration of the injectant at a given point becoming smaller as S/D is increased.
Direct transformation of 2,3-epoxy alcohols into hydroxy carbonates under mildly basic conditions

Abstract 2,3-Epoxy alcohols are transformed into the corresponding C2-inverted hydroxy carbonates upon treatment with cesium carbonate-powdered 3-A molecular sieves in N,N-dimethylformamide under one atmosphere of carbon dioxide at 23–78 °C.
Epsilon-safe planning

We introduce an approach to high-level conditional planning we call e-safe planning. This probabilistic approach commits us to planning to meet some specified goal witch a probability of success of at least 1 - e for some user-supplied e. We describe several algorithms for e-safe planning based on conditional planners. The two conditional planners we discuss are Peot and Smith's nonlinear conditional planner, CNLP, and our own linear conditional planner, PLINTH. We present a straightforward extension to conditional planners for which computing the necessary probabilities is simple, employing a commonly-made but perhaps overly-strong independence assumption. We also discuss a second approach to e-safe planning which relaxes this independence assumption, involving the incremental construction of a probability dependence model in conjunction with the construction of the plan graph.
fastSTRUCTURE: Variational Inference of Population Structure in Large SNP Data Sets

Tools for estimating population structure from genetic data are now used in a wide variety of applications in population genetics. However, inferring population structure in large modern data sets imposes severe computational challenges. Here, we develop efficient algorithms for approximate inference of the model underlying the STRUCTURE program using a variational Bayesian framework. Variational methods pose the problem of computing relevant posterior distributions as an optimization problem, allowing us to build on recent advances in optimization theory to develop fast inference tools. In addition, we propose useful heuristic scores to identify the number of populations represented in a data set and a new hierarchical prior to detect weak population structure in the data. We test the variational algorithms on simulated data and illustrate using genotype data from the CEPH-Human Genome Diversity Panel. The variational algorithms are almost two orders of magnitude faster than STRUCTURE and achieve accuracies comparable to those of ADMIXTURE. Furthermore, our results show that the heuristic scores for choosing model complexity provide a reasonable range of values for the number of populations represented in the data, with minimal bias toward detecting structure when it is very weak. Our algorithm, fastSTRUCTURE, is freely available online at http://pritchardlab.stanford.edu/structure.html.
The aerodynamics of jumping rope

We consider the influence of aerodynamic forces on the shape of a whirling filament that is held at both ends, i.e. a jump rope. At high Reynolds numbers, the rope curls out of the plane and towards the axis of rotation—a feature we demonstrate via experiment. We derive a pair of coupled nonlinear differential equations that characterize the steady-state shape of the rope, and the resulting eigenvalue problem is solved numerically. The solution depends on two dimensionless groups: the ratio between the length of the rope and the distance between its ends, and the relative magnitude of the aerodynamic to centrifugal forces. As the latter ratio is progressively increased, the tension in the rope and the out-of-plane deflection increases, until eventually the rope reaches a limiting shape. Finally, we show that the airflow-induced shape change leads to a relative reduction in drag and has implications for successful skipping.
The ground axiom

A new axiom is proposed, the Ground Axiom, asserting that the universe is not a nontrivial set forcing extension of any inner model. The Ground Axiom is first-order expressible, and any model of ZFC has a class forcing extension which satisfies it. The Ground Axiom is independent of many well-known set-theoretic assertions including the Generalized Continuum Hypothesis, the assertion V=HOD that every set is ordinal definable, and the existence of measurable and supercompact cardinals. The related Bedrock Axiom, asserting that the universe is a set forcing extension of a model satisfying the Ground Axiom, is also first-order expressible, and its negation is consistent.
High-Speed Centrifugal Compressor Instabilities during Speed Transients

Quasi-steady instability initiation studies do not model the actual operation of a compressor in an installed engine. Namely, gas turbine engine compressors are subject to transient operation. To provide needed high-speed centrifugal compressor instability initiation information addressing transient operation, an experimental study is performed to characterize the instability behavior of a high-speed centrifugal compressor during accelerations and decelerations at various throttle settings. Data are acquired from high response dynamic pressure transducers at the inlet and exit of the compressor. Analysis of these data shows that three distinct instabilities occur: Deep surge, mild surge, and rotating stall. The rotating stall is consistent with a nine-lobed stall pattern occurring in or near the diffuser. During accelerations, rotating stall occurs prior to surge initiation. During decelerations, all three instabilities are observed. Rotating stall is observed prior to and following both mild and deep surge.
Performance of LDPC Codes Under Faulty Iterative Decoding

Departing from traditional communication theory where decoding algorithms are assumed to perform without error, a system where noise perturbs both computational devices and communication channels is considered here. This paper studies limits in processing noisy signals with noisy circuits by investigating the effect of noise on standard iterative decoders for low-density parity-check (LDPC) codes. Concentration of decoding performance around its average is shown to hold when noise is introduced into message-passing and local computation. Density evolution equations for simple faulty iterative decoders are derived. In one model, computing nonlinear estimation thresholds shows that performance degrades smoothly as decoder noise increases, but arbitrarily small probability of error is not achievable. Probability of error may be driven to zero in another system model; the decoding threshold again decreases smoothly with decoder noise. As an application of the methods developed, an achievability result for reliable memory systems constructed from unreliable components is provided.
A Free-Lagrange method for 2-D compressible flows☆

Abstract Numerical algorithms for solving fluid flow problems are traditionally constructed in either an Eulerian or a Lagrangian reference frame. In the Lagrangian formulation, the mesh follows the fluid motion and this automatically guarantees the accurate treatment of interfaces. However, when large relative motions occur in the flow, the mesh becomes tangled and the problem must be “repaired” before it can continue. The Free-Lagrange Method overcomes this difficulty by automatically reconnecting the mesh when necessary during run time. The main advantage of the Free-Lagrange formulation is that problems complete in a minimum amount of calendar time with an accurate solution. Another advantage is that the general mesh structure permits a great deal of flexibility in generating the initial mesh. The disadvantage is that solutions may be more expensive in terms of CPU time because the general structure of the mesh means that gather/scatter parts of the code are not vectorized. Recent hardware developments help ameliorate this consideration.
Ergodic layered erasure one-sided interference channels

The sum capacity of a class of layered erasure onesided interference channels is developed under the assumption of no channel state information at the transmitters. Outer bounds are presented for this model and are shown to be tight for the following sub-classes: i) weak, ii) strong (mix of strong but not very strong (SnVS) and very strong (VS)), iii) ergodic very strong (mix of strong and weak), and (iv) a sub-class of mixed interference (mix of SnVS and weak). Each sub-class is uniquely defined by the fading statistics.
A methodology for the development of general knowledge-based vision systems

Expert system technology, especially techniques for rule-based knowledge engineering, has been successfully applied to many practical problems. Although there are inherent limitations in the complexity and power that can be achieved with traditional expert system approaches (Davis 1982), particularly when the number of rules is not constrained, there has been little evidence of its application to image interpretation. Typically, vision systems are highly system or application dependent and consequently it has been difficult to transfer them to different task domains. For example, there have been several systems developed for applications with aerial or satellite images (Bajcsy and Tavakoli 1976; Ballard et al. 1978; Faugeras and Price 1981; Nagao and Matsuyama 1980) but these systems have not been applied to other domains such as industrial scenes, medical applications, or road scenes. Only a few research efforts (Brooks 1981; Hanson and Riseman 1978c) have attempted to bridge task domains. We believe that a system employing a general methodology will be required if a large number of industrial applications are to be solved without requiring the construction of a customized system for each application. The bulk of this chapter will use results from outdoor scenes, specifically house scenes. However, we believe that our methodology can be applied in a straightforward manner to complex industrial applications by changing the knowledge base associated with the set of objects to be recognized. In an effort to motivate the reader to provide a sense of the potential, in the next section we have included the output of low-level algorithms applied to images of industrial parts.
Structural and Aeroelastic Characteristics of Truss-Braced Wings: A Parametric Study

flexible in nature. This paper presents a set of parametric studies of truss-braced-wing configurations to understand the influence of the wing geometry parameters on the wing structural and aeroelastic characteristics. The primary parametersconsideredherearethewinghalf-span,strutsweep,spanwiselocationofwing-strutjoint,andnumberof truss members in the wing configuration. Each truss-braced-wing parametric configuration is sized based on strength considerations and studied for aeroelastic behavior. The results indicate strong influence of all the parameters considered here. For most cases, increasing the half-span monotonically increases the wing weight and reduces both the natural frequencies and the flutter speed. A larger difference between the wing- and strut sweep angles is seen to increase wing weight, but with a positive influence on flutter speed for various truss-braced-wing configurations. The spanwise intersection location has distinct optima for wing weight and flutter speed, which typically lie in between 55 and 70%. These results are expected to provide guidance for future multidisciplinary design optimization studies for truss-braced-wing configurations.
From the design of a chiral Lewis acid catalyst to metal-catalyzed coupling reactions.

In this Perspective, I describe my group's nonobvious path from an interest in chiral Lewis acid catalysis to a project focused on the development of new palladium and nickel catalysts for carbon−carbon bond-forming reactions.
Properties of a cusp diamagnetic cavity boundary

While crossing through the high-altitude dayside cusp on 29 September 1978 and again on 30 October 1978, the ISEE-1 spacecraft observed enhanced energetic particle flux and a depressed and turbulent magnetic field, the signa- ture characteristics of a cusp diamagnetic cavity. As ISEE-1 approached the cavity during each event, a boundary sound- ing technique was used to measure properties of an emitting boundary. Sounding over multiple energy channels reveals an energy dependent boundary with lower energy particles filling a larger cavity than higher energy particles. Relative motion of the boundary as well as boundary orientation are also measured. The two cusp events were measured at dif- ferent locations and during different geomagnetic and solar wind conditions; however, they show similar results.
Secular Trends in Body Weight in Older Men Born Between 1877 and 1941: The Baltimore Longitudinal Study of Aging

Background. The prevalence of overweight and obesity has increased in all age groups, including older adults. However, it is not known whether higher body weight is maintained in the very old and in the years prior to death. The present study examines whether there are secular trends in body weight in old age among three birth cohorts. Methods. The study population includes 1,364 Caucasian men born between 1877 and 1941 from the Baltimore Longitudinal Study of Aging who were followed until death. Four hundred and seventy-seven men had body weight measured during the last 5 years prior to death. Body weight was measured biannually with the last visit occurring between 1959 and 2008. Differences in body weight at the last visit and body weight trajectories across birth cohorts were examined with linear regression and linear mixed-effect regression models. Results. Men born between 1920 and 1941 had signifi cantly higher body weight over the entire follow-up time compared with men born between 1900 and 1919 ( p < .001) and 1877 and 1899 ( p = .001), and the difference was also signifi cant between the two earlier birth cohorts ( p < .001). A signifi cant increasing trend in body weight across birth cohorts was also observed in the few years prior to death. Conclusions. In generally healthy men, there is a signifi cant secular increase in body weight over the adult life span and in the few years prior to death. This study confi rms that the obesity epidemic also extends into late life in the current elderly population.
Benzannulation of heterocyclic ring systems through coupling of Fischer carbene complexes and heterocycle-bridged enynes

An efficient annulation process resulting in heterocyclic rings fused to benzene rings has been discovered. The reaction is highly tolerant of numerous functional groups.
The Strategic Change Champions

In this paper, I argue that the quickest means for human resources (HR) and human resource development (HRD) functions to achieve strategic positions in their organizations is to foster their roles as change champions and as providers of people-oriented decision-support. HRD practitioners have been trapped in the midst of an identity crisis as they increasingly have had to relinquish their former roles as trainers. This paper outlines a new way forward for HR/HRD practitioners as they attempt to sort out their new organizational roles and function in contemporary organizations where the outsourcing of HR/HRD functions including employee relations, benefits, training, etc. is quickly becoming the norm.
Strength and speed training for elders with mobility disability.

The purpose of this study was to pilot test a function-focused exercise intervention consisting of strength and gait-speed training in elders with reduced walking speed, decreased walking endurance, and functional impairment. Twelve participants, 77.2 years old (+/-7.34), whose usual gait speed was or =1.0 m/s), endurance (> or =350 m), and functional ability (> or =10 score on performance battery) that were within normal limits after 12 weeks of training. Fastest gait speed (> or =1.5 m/s) and muscle strength also improved significantly. Improvements were maintained during follow-up testing after 3-6 months. In summary, a 12-week intervention for frail, mobility-disabled participants led to improvements in walking, function, and strength.
An empirical study of reliable multicast protocols over Ethernet-connected networks

Recent advances in multicasting over the Internet present new opportunities for improving communication performance for clusters of workstations. Realizing collective communication over reliable multicast can achieve higher performance than over reliable unicast primitives. The standard IP multicast, however, only supports unreliable multicast, which is difficult to use for building high level message passing routines. Thus, reliable multicast primitives must be implemented over the standard IP multicast to facilitate the use of multicast for high-performance communication on clusters of workstations. Although many reliable multicast protocols have been proposed for the wide area Internet environment, the impact of special features of local area networks (LANs) on the performance of the reliable multicast protocols has not been thoroughly studied. Efficient reliable multicast protocols for LANs must exploit these features to achieve the best performance. In this paper, we present our implementation of four types of reliable multicast protocols: the ACK-based protocols, the NAK-based protocols with polling, the ring-based protocols and the tree-based protocols. The protocols are implemented over IP multicast using the standard UDP interface. We evaluate the performance of the protocols over Ethernet-connected networks, study the impact of some special features of the Ethernet on the performance of the protocols and investigate the methods to exploit these features to improve communication performance.
Corporate Board Composition, Protocols, and Voting Behavior: Experimental Evidence

We examine voting by a board designed to mitigate conflicts of interest between privately informed insiders and owners. Our model demonstrates that, as argued by researchers and the business press, boards with a majority of trustworthy but uninformed "watchdog" agents can implement institutionally preferred policies. Our laboratory experiments strongly support this conclusion. Our model also highlights the necessity of penalties on insiders when there is dissension among board members. However, penalties for dissent appeared to have little impact on the experimental outcomes.
Mature Minors Should Have the Right to Refuse Life-Sustaining Medical Treatment

Imagine that you are a teenager and have cancer. You undergo a year of chemotherapy and after a brief return to normal life, you have a relapse. Your physician says that chemotherapy and radiation therapy could be tried, but a bone marrow transplant (BMT) is your only chance of a real cure. He tells you and your parents that you could die as a result of complications from the transplant, but without it you would only be expected to live one year. You and your family discuss the alternatives and decide to have the transplant. You ask what will happen if the BMT fails, but both your physician and your family tell you that right now you must fight to get better and not think negative thoughts. You do not ask any more questions.
PSA Bounces After Neoadjuvant Androgen Deprivation and External Beam Radiation: Impact on Definitions of Failure

Purpose: To determine the characteristics of prostate specific antigen (PSA) bounces after external beam radiation therapy (EBRT) with neoadjuvant androgen deprivation and their impact on definitions of biochemical failure. Methods and Materials: Characteristics of bounce were calculated for all patients treated by EBRT with neoadjuvant androgen deprivation at our institution between 1992 and 1998 (preexclusion analysis). Calculations were repeated for the subgroup that satisfied additional inclusion/exclusion criteria (postexclusion analysis). The percentage of bounces scoring as false positives according to the ASTRO definition of biochemical failure was compared with those for three alternative definitions (Vancouver, Nadir-plus-two, and Nadir-plus-three) using McNemar’s tests. Results: Thirty-nine percent (preexclusion cohort) and 56% (postexclusion cohort) of patients demonstrated a PSA bounce. Twenty percent (preexclusion analysis) and 25% (postexclusion analysis) of these bounces scored as biochemical failure according to the ASTRO definition. The Nadir-plus-three definition scored the smallest percentage of bounces as failure, but the difference between this definition and the ASTRO definition reached statistical significance in neither preexclusion nor postexclusion analyses (p > 0.070). Conclusions: A substantial proportion of patients treated by EBRT with neoadjuvant deprivation experienced a PSA bounce. A large percentage of these bounces scored as biochemical failure according to the ASTRO definition. The Nadir-plus-three definition is less vulnerable to this bias. © 2005 Elsevier Inc. Androgen deprivation, Prostate cancer, PSA, Radiation.
Impacts of information system vulnerabilities on society

After briefly presenting examples of potential vulnerabilities in computer systems which society relies on, the concept of risk analysis is introduced and applied to a simplified model for a nation's financial system. A sampling of specific technical safeguards to ameliorate the risk in this (or any) computer system is then given. The paper concludes with examples of questions to be asked before committing to any new technological system.
Electromagnetic energy around Hertzian dipoles

This paper considers the behavior of electromagnetic energy around Hertzian dipoles. The method of "causal surfaces" (surfaces through which there is no net flow of electromagnetic energy) is used to partition and track the energy. A variety of examples, involving both transient and harmonic time dependence, are presented, to illustrate the way in which static and/or reactive energy is converted to outgoing, uncoupled, "radiated" energy around a Hertzian or point dipole. The principal conclusion is that although accelerating charge may be thought of as the source of the radiation fields, the source of the radiated energy lies in the static and/or reactive field energy near an antenna, and not "in" or "on" an antenna itself.
New Venture Evolution and Managerial Capabilities

This study examines factors influencing changes in the top management of start-up firms. Whereas a significant amount of research has examined top management transitions in established firms, we know much less about the factors influencing the evolution of top management capabilities in a new firm. Our research examines these issues in a sample of new ventures founded from 1983 through 1995, examining each firm for seven years after its founding to evaluate the conditions that influence a firm's changes in top management. Results indicate that top management team changes occur in cases of very low or very high firm growth, but are mitigated by a functionally diverse top management team. Power and control of inside and outside constituencies also affect changes in top management, with venture capital ownership and board representation increasing change in top management, and managerial ownership decreasing changes.
FDTD computation of human eye exposure to ultra-wideband electromagnetic pulses

With an increase in the application of ultra-wideband (UWB) electromagnetic pulses in the communications industry, radar, biotechnology and medicine, comes an interest in UWB exposure safety standards. Despite an increase of the scientific research on bioeffects of exposure to non-ionizing UWB pulses, characterization of those effects is far from complete. A numerical computational approach, such as a finite-difference time domain (FDTD) method, is required to visualize and understand the complexity of broadband electromagnetic interactions. The FDTD method has almost no limits in the description of the geometrical and dispersive properties of the simulated material, it is numerically robust and appropriate for current computer technology. In this paper, a complete calculation of exposure of the human eye to UWB electromagnetic pulses in the frequency range of 3.1-10.6, 22-29 and 57-64 GHz is performed. Computation in this frequency range required a geometrical resolution of the eye of 0.1 mm and an arbitrary precision in the description of its dielectric properties in terms of the Debye model. New results show that the interaction of UWB pulses with the eye tissues exhibits the same properties as the interaction of the continuous electromagnetic waves (CWs) with the frequencies from the pulse's frequency spectrum. It is also shown that under the same exposure conditions the exposure to UWB pulses is from one to many orders of magnitude safer than the exposure to CW.
Educational Debt Burden and Career Choice: Evidence from a Financial Aid Experiment at NYU Law School

This paper examines the influence of psychological responses to debt on career choices from an experiment in which alternative financial aid packages were assigned by lottery to a set of law school admits. The packages had equivalent monetary value, but one required the student to take on a loan that would be paid for by the school if he worked in public interest law, while the other covered tuition as long as the student worked in public interest law. If he did not, the student would be required to reimburse the school. Tuition assistance recipients have a 36 to 45 percent higher public interest placement rate and, when lottery results were announced before enrollment, were twice as likely to enroll.
Ranolazine prevents heart failure with preserved ejection fraction, diastolic dysfunction, and left ventricular hypertrophy in a hypertensive murine model

Background: Recent in vitro studies on failing human heart muscle has suggested that ranolazine (RAN), a novel antianginal drug known to inhibit late sodium current, may improve diastolic dysfunction (DD) caused by hypertension (HTN)-induced oxidative stress. By improving DD, RAN can improve heart failure with preserved ejection fraction (HFPEF). Methods: Amouse model of DDwas developed by inducing mild HTN by unilateral nephrectomy, deoxycorticosterone acetate (DOCA) pellet implantation, and substituting drinking water with 1% NaCl. Control animals underwent sham operation and drank regular tap water. RAN 50 (mg/kg) was given orally twice a day. Weekly blood pressures (BPs) and heart rates (HRs) were measured using tail-cuff plethysmography. Cardiac function and left ventricular posterior wall thickness (LVPWd) were measured by echocardiogram under light anesthesia using isoflurane. Treatment durationwas for 3weeks and 7weeks. Pulmonary congestion was assessed by lung to body weight (L/BW) ratio. Results: Compared to controls, DOCA mice were hypertensive (BP 112 ±4 vs. 89±2 mmHg) and had DD evidenced by a low LV inflow propagation velocity Vp (28.1±0.5 vs. 47.2±1 cm/s⁎), a low mitral annulus early longitudinal velocity E' (2.70 vs. 4.40 cm/s⁎), and a high E/E' ratio (29.3±1.5 vs. 18.0±0⁎). DOCA mice had LVH as evidenced by high heart/BW ratio (6.22±0.15 vs. 4.90±0.22 mg/g⁎) and increased LVPWd (0.82±0.22 vs. 0.74±0.01 mm⁎). There was no systolic dysfunction in either group. RAN pretreatment effectively prevented DD and LVH in DOCA mice as evidenced by high E' (3.9 Vs 2.70 cm/s⁎), low E/E' (18.8±1.0⁎), high Vp (41±2Vs 28.1±0.5 cm/s⁎), lowheart/BW ratio (4.79±0.11 mg/g⁎), and low LVPWd thickness (0.76±0.01 vs. 0.82±0.02 mm⁎). RAN had no effect on HR [625±18 vs. 630±20 bpm, P=not significant (NS)]. RAN pretreatment effectively prevented development of heart failure in DOCA mice at 7 weeks as evidenced by significantly lower L/BW ratios when compared with untreated DOCA mice (0.41±0.002 vs. 0.52±0.02 mg/g⁎). Conclusions: RANhas prevented DD, LVH, and HFPEF in a hypertensive murine model of DD. Prevention of heart failure in our model warrants additional animal andhuman studies to further evaluate the therapeutic potential of RAN in HFPEF (Mean±S.E.M., ⁎Pb.05).
Radio Synchrotron Emission from a Bow Shock around the Gas Cloud G2 Heading toward the Galactic Center

A dense ionized cloud of gas has been recently discovered to be moving directly toward the supermassive black hole, Sgr A ∗ , at the Galactic center. In 2013 June, at the pericenter of its highly eccentric orbit, the cloud will be approximately 3100 Schwarzschild radii from the black hole and will move supersonically through the ambient hot gas with a velocity of vp ≈ 5400 km s −1 . A bow shock is likely to form in front of the cloud and could accelerate electrons to relativistic energies. We estimate via particle-in-cell simulations the energy distribution of the accelerated electrons and show that the non-thermal synchrotron emission from these electrons might exceed the quiescent radio emission from Sgr A ∗ by a factor of several. The enhanced radio emission should be detectable at GHz and higher frequencies around the time of pericentric passage and in the following months. The bow shock emission is expected to be displaced from the quiescent radio emission of Sgr A ∗ by ∼33 mas. Interferometric observations could resolve potential changes in the radio image of Sgr A ∗ at wavelengths 6c m.
Palladium-promoted derivatizations of novel C-fused penem ring systems

Abstract Palladium-catalyzed coupling reactions and carboxylations are reported for the functionalization of bicyclic beta-lactam ring systems related to the penem family of antibiotics.
Formulation and solution of inverse spaghetti problem - Application to beam deployment dynamics

A finite element model of the dynamics of axially moving, highly flexible beams is presented. The model is based on a geometrically nonlinear beam formulation that allows for large overall motions. To account for the varying length of a deploying beam, a moving finite element reference grid is incorporated within the nonlinear beam formulation such that the number of finite element nodes remains fixed and the finite element length is allowed to vary. Hamilton's law is used to formulate the equations of motion, and a transient integration solution procedure is derived from a space-time finite element discretization of the Hamiltonian variational principle. Computational results of the methodology are presented for a planar inverse-spaghetti problem. HE dynamics of axially moving beamlike structures are becoming increasingly important for the analysis of spacecraft and large space structures that deploy flexible appendages such as antenna, stabilizing booms, solar arrays, and long trusslike structures as well as for other applications such as magnetic tape drives, printing machines, traveling cables, and band saws. An extensive amount of research has focused on the modeling of axially moving continua to analyze the dynamic behavior of such structures. One of the most common models of axially moving continua that has received the most attention is the traveling string problem. In what he termed the "spaghetti problem," Carrier1 analyzed the motion of a string being accelerated upward into a fixed orifice. In other works since then, analytical expressions representing both linear and nonlinear vibrations of axially moving strings subject to various support conditions have been derived.2'9 The dynamics of beamlike structures traveling between or over fixed supports have also been studied to address industrial applications such as high-speed tape drives and band saws.10'13 To address spacecraft applications in which antenna or other long flexible structures are deployed from a host satellite, the dynamics of a cantilever beam that is ejected from a single fixed guide are modeled using Bernoulli-Euler beam theory in Ref. 14. In a quite different approach, the extrusion of a beam from a rotating base is modeled using a series of elastically connected rigid links in which the number of rigid links are continuously increased/decreased to account for deployment/ retrieval of the beam.15 General formulations of axially moving Bernoulli-Euler beam models cantilevered to a rotating rigid host body have also been developed to study the effect of appendage deployment on the attitude dynamics of orbiting spacecraft.16"20 All of these given analyses are based on an assumption of small elastic deformations. With the exception of the discrete spring-mass model of Ref. 15, all of the other models that have been referenced thus far use linear combinations of space-depende nt admissible functions of a time-varying length weighted by time-dependen t generalized coordi
Cover Me: Managers' Responses to Changes in Analyst Coverage in the Post-Regulation FD Period

ABSTRACT: We show that managers increase the volume of public financial guidance in response to decreases in analyst coverage of their firms, particularly to decreases that are driven by exogenous reduction in brokerage firm size. Managers do not respond to increases in analyst coverage. The managerial guidance response to decreases in coverage reflects the trade-off between the marginal benefits from analyst coverage and the marginal costs of providing guidance. Specifically, the response is concentrated within firms engaging in equity issuance activities, firms with low stock liquidity, and firms with low current guidance levels. The response is also concentrated within firms whose remaining analyst pool is smaller in number and/or has a lower percentage of analysts who are positive about the firm or who belong to a large brokerage house. Overall, our results shed insights on the interaction between managers and analysts and on how the value of analysts, as perceived by managers, varies in the cross-sec...
The Maximal Number of Regular Totally Mixed Nash Equilibria

Abstract LetS=∏ni=1 Sibe the strategy space for a finite n-person game. Let (s10, …, sn0)∈Sbe any strategyn-tuple, and letTi=Si−{si0},i=1, …, n. We show that the maximum number of regular totally mixed Nash equilibria of a game with strategy setsSiis the number of partitions P ={P1, …, Pn} of ∪i Tisuch that, for eachi, |Pi|=|Ti| andPi∩Ti=∅. The bound is tight, as we give a method for constructing a game with the maximum number of equilibria.Journal of Economic LiteratureClassification Number C72.
Longitudinal cooling of a strongly magnetized electron plasma

The optimal values of Q and (/spl omega/ - /spl Omega//sub r/) for cooling a pure electron plasma with a microwave bath have been calculated. An electron plasma which has no internal degree of freedom, cannot be cooled down below a heat bath temperature. However, the longitudinal cooling can be achieved by energy transfer from the poorly cooled parallel degree of freedom to the well cooled (by synchrotron radiation) perpendicular degree of freedom. To do this, we introduce a microwave bath to the electron plasma. A microwave tuned to a frequency below the gyrofrequency of the electron forces an electron moving towards the microwave to absorb a photon and then to move up one in Landau state. The electron loses longitudinal momentum in this process, so that the longitudinal energy can be reduced. On the basis that most of the electrons are in the ground or first excited state, we set up a transition equation and develop a FEM code. With an appropriate condition for B-field and intensity of the microwave, the cooling times for several values of Q and (/spl omega/ - /spl Omega//sub r/) are calculated and the optimal values are found. Applying the optimal values at appropriate times in a cooling process, the best cooling can be obtained. For an electron plasma magnetized with 10 T B-field, cooling to the solid state can occur within 2 hours. Without this optimization, times were always several hours, longer than the life time of the plasma in real system.
Kerdock Codes for Limited Feedback Precoded MIMO Systems

Codebook based limited feedback is a practical way to obtain partial channel state information at the transmitter in a precoded multiple-input multiple-output wireless system. In this correspondence, we propose a systematic codebook design. The proposed Kerdock codebook consists of multiple mutually unbiased unitary basis matrices with quaternary alphabet and the identity matrix. We propose to derive the beamforming and precoding codebooks from this base codebook, eliminating the requirement to store multiple codebooks. Furthermore, we show that quaternary alphabet facilitates efficient codebook storage and codeword search. We derive the chordal distance for two and four antenna codebooks, showing that the proposed codebooks compare favorably with prior designs. Monte Carlo simulations compare achievable rates and error rates for different codebooks sizes.
Precession of isolated neutron stars – II. Magnetic fields and type II superconductivity

We consider the physics of free precession of a rotating neutron star with an oblique magnetic field. We show that if the magnetic stresses are large enough, then there is no possibility of steady rotation, and precession is inevitable. Even if the magnetic stresses are not strong enough to prevent steady rotation, we argue that the local minimum energy state, at fixed magnetic field obliquity, is one in which the star precesses. Since the moment of inertia tensor is inherently triaxial in a magnetic star, the precession is periodic but not sinusoidal in time, in agreement with observations of PSR 1828-11. However, the problem we consider is not just precession of a triaxial body. If magnetic stresses dominate, the amplitude of the precession is not set just by the angle between the rotational angular velocity and any principal axis, which allows it to be small without suppressing oscillations of timing residuals at harmonics of the precession frequency. We argue that magnetic distortions can lead to oscillations of timing residuals of the amplitude, period and relative strength of harmonics observed in PSR 1828-11 if magnetic stresses in its core are about 200 times larger than the classical Maxwell value for its dipole field, and the stellar distortion induced by these enhanced magnetic stresses is about 100-1000 times larger than the deformation of the crust of the neutron star. Magnetic stresses this large can arise if the core is a type II superconductor or from toroidal fields ∼10 1 4 G if the core is a normal conductor. The observations of PSR 1828-11 appear to require that the magnetic distortion of the neutron star be slightly prolate.