Gluon contributions to the pion mass and light cone momentum fraction

We calculate the matrix elements of the gluonic contributions to the energy-momentum tensor for a pion of mass 600 < Mpi < 1100 MeV in quenched lattice QCD. We find that gluons contribute (37 +/- 8 +/- 12)% of the pion's light cone momentum. The bare matrix elements corresponding to the trace anomaly contribution to the pion mass are also obtained. The discretizations of the energy-momentum tensor we use have other promising applications, ranging from calculating the origin of hadron spin to QCD thermodynamics.Comment: 4 pages, 2 figure

The Legalization of the Workplace

This study uses longitudinal data on nearly 300 American employers over the period 1955-85 to analyze the adoption of disciplinary hearings and grievance procedures for nonunion salaried and hourly employees. Hypotheses are developed from an institutional perspective that focuses, first, on uncertainty arising from government mandates concerning equal employment opportunity and affirmative action and, second, on the role of the human relations professions in constructing employment-relations law and prescribing models of compliance. Event-history techniques are used to test these hypotheses against competing arguments concerning the internal structure and labor market position of employing organizations. Results on all outcomes strongly support the institutionalist model.Sociolog

Equal Opportunity Law and the Construction of Internal Labor Markets

Internal labor markets have been explained with efficiency and control arguments; however, retrospective event-history data from 279 organizations suggest that federal Equal Employment Opportunity (EEO) law was the force behind the spread of formal promotion mechanisms after 1964. The findings highlight the way in which American public policy, with its broad outcome-oriented guidelines for organizations, stimulates managers to experiment with compliance mechanisms with an eye to judicial sanction. In response to EEO legislation and case law, personnel managers devised and diffused employment practices that treat all classes of workers as ambitious and achievement oriented in the process of formalizing and rationalizing promotion decisions.Sociolog

The Nature of the Giant Outbursts in the Bursting Pulsar GRO J 1744-28

We investigate the possible role of an accretion disk instability in producing the giant outbursts seen in GRO J1744-28. Specifically, we study the global, time dependent evolution of the Lightman-Eardley instability which can develop near the inner edge of an accretion disk when the radiation pressure becomes comparable to the gas pressure. Broadly speaking, our results are compatible with earlier works by Taam \& Lin and by Lasota \& Pelat. The uniqueness of GRO J1744-28 appears to be associated with the constraint that, in order for outbursts to occur, the rate of accretion at the inner edge must be within a narrow range just above the critical accretion rate at which radiation pressure is beginning to become significant.Comment: 11 pages in .tex file, 4 Postscript figures, .tex file uses aasms.sty; Ap. J. L. 1996, in pres

The Expansion of Mass Education in Botswana: Local and World Society Perspectives

This is the published version. Copyright 1993 University of Chicago Press.Since the end of the Second World War, the growth of education is notable for several reasons. First, the institutions of mass education have spread to virtually all countries despite vast differences in political, economic, social, and cultural organization. Second, rates of enrollment around the world are high and represent enormous financial investments by many impoverished states and economies.1 And, third, the rapidity of educational expansion across states was unanticipated, its speed catching by surprise both theorists and practitioners alike

Scheduling time-critical graphics on multiple processors

This paper describes an algorithm for the scheduling of time-critical rendering and computation tasks on single- and multiple-processor architectures, with minimal pipelining. It was developed to manage scientific visualization scenes consisting of hundreds of objects, each of which can be computed and displayed at thousands of possible resolution levels. The algorithm generates the time-critical schedule using progressive-refinement techniques; it always returns a feasible schedule and, when allowed to run to completion, produces a near-optimal schedule which takes advantage of almost the entire multiple-processor system

Implications of Minimum Summer Water Releases from Gavins Point for Power Plants

The purpose of this study is to evaluate the potential impacts on power plants of minimum water releases from Gavins Point to the Missouri River as presented in the U.S. Army Corp of Engineers' (Corps) Master Manual (Corps 2004). The Corps regulates the flow of the Missouri River to support navigation and control flooding by controlling water releases from Gavins Point, the lowest of the six reservoirs

Radioactive Probes of the Supernova-Contaminated Solar Nebula: Evidence that the Sun was Born in a Cluster

We construct a simple model for radioisotopic enrichment of the protosolar nebula by injection from a nearby supernova, based on the inverse square law for ejecta dispersion. We find that the presolar radioisotopes abundances (i.e., in solar masses) demand a nearby supernova: its distance can be no larger than 66 times the size of the protosolar nebula, at a 90% confidence level, assuming 1 solar mass of protosolar material. The relevant size of the nebula depends on its state of evolution at the time of radioactivity injection. In one scenario, a collection of low-mass stars, including our sun, formed in a group or cluster with an intermediate- to high-mass star that ended its life as a supernova while our sun was still a protostar, a starless core, or perhaps a diffuse cloud. Using recent observations of protostars to estimate the size of the protosolar nebula constrains the distance of the supernova at 0.02 to 1.6 pc. The supernova distance limit is consistent with the scales of low-mass stars formation around one or more massive stars, but it is closer than expected were the sun formed in an isolated, solitary state. Consequently, if any presolar radioactivities originated via supernova injection, we must conclude that our sun was a member of such a group or cluster that has since dispersed, and thus that solar system formation should be understood in this context. In addition, we show that the timescale from explosion to the creation of small bodies was on the order of 1.8 Myr (formal 90% confidence range of 0 to 2.2 Myr), and thus the temporal choreography from supernova ejecta to meteorites is important. Finally, we can not distinguish between progenitor masses from 15 to 25 solar masses in the nucleosynthesis models; however, the 20 solar mass model is somewhat preferred.Comment: ApJ accepted, 19 pages, 3 figure