1,817 research outputs found
Dissipative contributions to epsilon'/epsilon
The time evolution and decay of the neutral kaon system can be described
using quantum dynamical semigroups. Non-standard terms appear in the expression
of relevant observables; they can be parametrized in terms of six, new
phenomenological constants. We discuss how the presence of these constants
affects the determination of the parameter epsilon'/epsilon.Comment: 11 pages, plain-Te
Development of single-cell protectors for sealed silver-zinc cells
Three design approaches to cell-level protection were developed, fabricated, and tested. These systems are referred to as the single-cell protector (SCP), multiplexed-cell protector(MCP). To evaluate the systems 18-cell battery packs without cell level control were subjected to cycle life test. A total of five batteries were subjected to simulate synchronous orbit cycling at 40% depth of discharge at 22C. Batteries without cell-level protection failed between 345 and 255 cycles. Cell failure in the cell level protected batteries occurred between 412 and 540. It was determined that the cell-level monitoring and protection is necessary to attain the long cycle life of a AgZn battery. The best method of providing control and protection of the AgZn cells depends on the specific application and capability of the user
Prison(er) auto/biography, 'true crime', and teaching, learning, and research in criminology
The main aim of this essay is to explore prisoner life writing within the specific, richly and multiply dependent context of teaching and learning undergraduate criminology at an English university, from the authorial viewpoint of a teacher and her students as budding criminologists and co-authors. This article seeks to redress a continuing resistance to life history approaches in the teaching of criminology, despite the discipline being formally devoted to the understanding of the meaning and experience of imprisonment in all its forms and consequences. What follows is a trucated narrative of what students had to say on the fascinating subjects of prisoner auto/biography and its place in popular and expert discourses on crime, criminality, and punishment, contextualised within the academic discipline of criminology
Development of single cell protectors for sealed silver-zinc cells, phase 1
A single cell protector (SCP) assembly capable of protecting a single silver-zinc (Ag Zn) battery cell was designed, fabricated, and tested. The SCP provides cell-level protection against overcharge and overdischarge by a bypass circuit. The bypass circuit consists of a magnetic-latching relay that is controlled by the high and low-voltage limit comparators. Although designed specifically for secondary Ag-Zn cells, the SCP is flexible enough to be adapted to other rechargeable cells. Eighteen SCPs were used in life testing of an 18-cell battery. The cells were sealed Ag-Zn system with inorganic separators. For comparison, another 18-cell battery was subjected to identical life test conditions, but with battery-level protection rather than cell-level. An alternative approach to the SCP design in the form of a microprocessor-based system was conceptually designed. The comparison of SCP and microprocessor approaches is also presented and a preferred approach for Ag-Zn battery protection is discussed
The Mg/Ca–temperature relationship in brachiopod shells: calibrating a potential palaeoseasonality proxy
Brachiopods are long-lived, long-ranging, extant organisms, of which some groups precipitate a relatively diagenetically stable low magnesium calcite shell. Previous work has suggested that the incorporation of Mg into brachiopod calcite may be controlled by temperature (Brand et al., 2013). Here we build upon this work by using laser ablation sampling to define the intra-shell variations in two modern brachiopod species,Terebratulina retusa (Linnaeus, 1758) and Liothyrella neozelanica (Thomson, 1918). We studied three T. retusa shells collected live from the Firth of Lorne, Scotland, which witnessed annual temperature variations on the order of 7 °C, in addition to four L. neozelanica shells, which were dredged from a water depth transect (168–1488 m) off the north coast of New Zealand. The comparison of intra-shell Mg/Ca profiles with shell δ<sup>18</sup>O confirms a temperature control on brachiopod Mg/Ca and supports the use of brachiopod Mg/Ca as a palaeoseasonality indicator. Our preliminary temperature calibrations are Mg/Ca = 1.76 ± 0.27 e<sup>(0.16 ± 0.03)T</sup>, R<sup>2</sup> = 0.75, for T. retusa and Mg/Ca = 0.49 ± 1.27 e<sup>(0.2 ± 0.11)T</sup>, R<sup>2</sup> = 0.32, for L. neozelanica (errors are 95% confidence intervals)
Developmental Expression of Elements of Hepatic Cholesterol Metabolism In The Rat
The expression of several key enzymes and receptors of rat hepatic cholesterol metabolism was studied during development. Among major findings were: acyl coenzyme A:cholesterol acyltransferase, the cholesteryl ester hydrolases, cholesterol-7 alpha-hydroxylase and the alpha 2-macroglobulin receptor (LRP) were very low in fetal livers, but all were induced shortly before birth, suggesting that these elements are important for extrauterine life. Although the other elements continued to increase, by day 6 of postnatal life, cholesterol-7 alpha-hydroxylase had reached undetectable levels. It reappeared by day 12 of suckling, placing it in the group of late-appearing activities necessary for the fully mature hepatic phenotype. Changes in acyl coenzyme A:cholesterol acyltransferase activity appeared due predominantly to changes in amount of active protein. The cholesteryl ester hydrolase (CEH) activities all showed different developmental patterns, suggesting that each was a unique activity. The bile salt- dependent CEH activity was much higher in the suckling period than in the adult where it was almost undetectable, suggesting that this CEH may have its major importance in the suckling period of development. Low density lipoprotein receptors exhibited a pattern very different from that of the alpha 2-macroglobulin receptors and did not show consistent correlation with any other elements. At some developmental time points, the relationships amongst the elements differed significantly from the adult pattern. These studies provide for the first time an integrated picture of developmental expression of key elements of hepatic cholesterol metabolism and set the stage for further studies on their modes of regulation
Disorder and nanopatterning in ordered binary alloys: in situ ion irradiation and kinetic Monte Carlo simulation
We study the effects of temperature and disordering rate on the ordered microstructures of real and simulated binary alloys. The behavior of Cu3Au, an alloy with L12 chemical order, is investigated experimentally through in situ electron diffraction and dark-field transmission electron microscopy. Under irradiation with 500 keV Ne+ ions, our diffraction analysis reveals a similar, but steeper, trend in disordering rate as previously reported by resistivity. Further investigations by superlattice, dark-field imaging lead to the discovery of temperature and dose rate dependent alterations to the ordered microstructure of the alloy. The process appears to be driven by the nucleation of small, highly ordered domains within the existing microstructure. We attempt to simulate these and other disordering behaviors through a kinetic Monte Carlo method. For simplicity, we focus these investigations on two-dimensional, ordered AB alloys featuring various first and second neighbor ordering energies. Disorder is imposed in these simulated alloys through manipulation of vacancy-atom exchange rates and forced atomic replacement. For certain disordering-temperature conditions and ordering energies 2/1≲0.5, a previously unreported patterning of order is observed, dividing the ordered microstructure into competing, highly ordered domains. This behavior is rationalized in terms of decreased anti-phase boundary energies at the given ordering energies, and a physical picture of the patterning reaction is presented. The application of this picture to Cu3Au is deemed plausible and future work proposed
Resonant-tunneling diodes with emitter prewells
Includes bibliographical references (page 1304).Resonant-tunneling diodes (RTDs) incorporating an emitter prewell structure are studied both theoretically and experimentally in order to investigate the utility of the emitter region as a device design parameter. The experiments show a tendency for peak bias, current, and the peak-to-valley ratio to increase for wider prewells, behavior likewise seen in both very simple and detailed calculations. Both the simple and more complete models point to interactions between states associated with the prewell and the main quantum well as the reasons for the increase in peak current. These results suggest design guidelines to affect peak bias, current, or the peak-to-valley ratio of RTDs
Evaluation of cholesterol and vitamin E concentrations in adult alpacas and nursing crias
The objective of this study was to determine if serum cholesterol and vitamin E concentrations change with production and physiologic state in alpacas. Blood was collected from 3 groups of alpacas. An adult female group was sampled in the periparturient period and once monthly until their offspring were weaned. Crias born to the females were sampled after birth, then once monthly until weaning. A group consisting of males was sampled once monthly throughout the study period. Serum vitamin E and cholesterol concentrations were measured and vitamin E to cholesterol ratios was calculated. Vitamin E concentrations were similar throughout the different physiologic states. Cria vitamin E concentrations closely correlated to that of their dam. Significant cholesterol concentration fluctuations in crias occurred after 4 weeks of life possibly due to milk fat content. After weaning, the cholesterol concentrations became similar to the adult animals within study. Vitamin E concentrations varied with age in crias as they transitioned from a milk to forage based diet. Cholesterol fluctuated with altered physiologic and metabolic demands, most noticeable in the crias. Further studies are needed to determine if vitamin E to cholesterol ratios would be more appropriate to fully assess the vitamin E status in nursing crias
Recapture Heterogeneity in Cliff Swallows: Increased Exposure to Mist Nets Leads to Net Avoidance
Ecologists often use mark-recapture to estimate demographic variables such as abundance, growth rate, or survival for samples of wild animal populations. A common assumption underlying mark-recapture is that all animals have an equal probability of detection, and failure to meet or correct for this assumption–as when certain members of the population are either easier or more difficult to capture than other animals–can lead to biased and inaccurate demographic estimates. We built within-year and among-years Cormack-Jolly-Seber recaptures-only models to identify causes of capture heterogeneity for a population of colonially nesting cliff swallows (Petrochelidon pyrrhonota) caught using mist-netting as a part of a 20- year mark-recapture study in southwestern Nebraska, U.S.A. Daily detection of cliff swallows caught in stationary mist nets at their colony sites declined as the birds got older and as the frequency of netting at a site within a season increased. Experienced birds’ avoidance of the net could be countered by sudden disturbances that startled them into a net, such as when we dropped a net over the side of a bridge or flushed nesting cliff swallows into a stationary net positioned at a colony entrance. Our results support the widely held, but seldom tested, belief that birds learn to avoid stationary mist nets over time, but also show that modifications of traditional field methods can reduce this source of recapture heterogeneity
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