24,291 research outputs found
Dynamics of a pinch discharge driven by a high current pulse-forming network
Dynamics of linear pinch discharge driven by high current pulse-forming network - snowplow mode
Structure, bonding and morphology of hydrothermally synthesised xonotlite
The authors have systematically investigated the role of synthesis conditions upon the structure and morphology of xonotlite. Starting with a mechanochemically prepared, semicrystalline phase with Ca/Si=1, the authors have prepared a series of xonotlite samples hydrothermally, at temperatures between 200 and 250 degrees C. Analysis in each case was by X-ray photoelectron spectroscopy, environmental scanning electron microscopy and X-ray diffraction. The authors’ use of a much lower water/solid ratio has indirectly confirmed the ‘through solution’ mechanism of xonotlite formation, where silicate dissolution is a key precursor of xonotlite formation. Concerning the role of temperature, too low a temperature (~200 degrees C) fails to yield xonotlite or leads to increased number of structural defects in the silicate chains of xonotlite and too high a temperature (>250 degrees C) leads to degradation of the xonotlite structure, through leaching of interchain calcium. Synthesis duration meanwhile leads to increased silicate polymerisation due to diminishing of the defects in the silicate chains and more perfect crystal morphologies
Winter wheat: A model for the simulation of growth and yield in winter wheat
The basic ideas and constructs for a general physical/physiological process level winter wheat simulation model are documented. It is a materials balance model which calculates daily increments of photosynthate production and respiratory losses in the crop canopy. The partitioning of the resulting dry matter to the active growing tissues in the plant each day, transpiration and the uptake of nitrogen from the soil profile are simulated. It incorporates the RHIZOS model which simulates, in two dimensions, the movement of water, roots, and soluble nutrients through the soil profile. It records the time of initiation of each of the plant organs. These phenological events are calculated from temperature functions with delays resulting from physiological stress. Stress is defined mathematically as an imbalance in the metabolite supply; demand ratio. Physiological stress is also the basis for the calculation of rates of tiller and floret abortion. Thus, tillering and head differentiation are modeled as the resulants of the two processes, morphogenesis and abortion, which may be occurring simulaneously
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Justification bias in self-reported disability: New evidence from panel data
The relationship between health and work is frequently investigated using self-assessments of disability from social surveys. The complication is that respondents may overstate their level of disability to justify non-employment and welfare receipt. This study provides new evidence on the existence and magnitude of justification bias by exploiting a novel feature of a large longitudinal survey: each wave respondents are asked identical disability questions twice; near the beginning and end of the face-to-face interview. Prior to answering the second disability question, respondents are asked a series of questions that increase the salience of their employment and welfare circumstances. Justification bias is identified by comparing the variation between the two measures within-individuals over time, with the variation in employment status over time. Results indicate substantial and statistically significant justification bias; especially for men and women who receive disability pensions
Mechanism for a next-to-lowest lying scalar meson nonet
Recent work suggests the existence of a non-conventional lowest-lying scalar
nonet containing the a0(980). Then the a0(1450) and also the K0*(1430) are
likely candidates to belong to a conventional p-wave nonet. However
a comparison of their properties with those expected on this basis reveals a
number of puzzling features. It is pointed out that these puzzles can be
resolved in a natural and robust way by assuming a ``bare'' conventional p-wave
scalar nonet to mix with a lighter four quark
scalar nonet to form new ``physical'' states. The essential mechanism is driven
by the fact that the isospinor is lighter than the isovector in the unmixed multiplet.Comment: 22 pages, 6 figure
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Who provides inconsistent reports of their health status? The importance of age, cognitive ability and socioeconomic status
Self-assessed health (SAH) measures are widely used in models of health and health inequalities. Such models assume that SAH is a reliable measure of health status. We utilise a unique feature of a national longitudinal survey to examine the consistency of responses to a standard SAH question that is asked twice to the same individual in close temporal proximity in up to three waves (2001, 2009, and 2013). In particular, we analyse whether the consistency of responses varies with personal characteristics. The main analysis sample includes 18,834 individual-year observations. We find that 57% of respondents provide inconsistent reports at least once. Characteristics that are associated with significantly higher inconsistencies are age, education, cognitive ability, and time between responses. The results suggest that there are systematic differences in the ability of individuals' to self-evaluate and summarise their own health. Consequently, failure to account for such error may lead to large estimation biases in models of health outcomes, particularly with respect to the relationship between education, cognitive ability, and health
Understanding the Nature of Non-Profit Incubators with Other Sector Incubators in the Founding of Social Change Organisations by Social Entrepreneurs
Incubators have been studied extensively in the private sector, such as those that engage in technological innovation or growing small businesses. The scholarship has not sufficiently explored the efforts of incubators in the nonprofit sector that help create programs supporting, mentoring, and cultivating social entrepreneurs. There are numerous documented cases of nonprofit organizations establishing initiatives that help motivated entrepreneurs achieve social change; but research is lagging in developing a systematic understanding of these effort’s impact, and the factors associated with the success of nonprofit initiatives that support social entrepreneurs. This paper seeks to understand the nature of nonprofit organizations that support and cultivate social entrepreneurs. We rely on a unique data set from survey research on nonprofit initiatives across three U.S. Census Regions. Results indicate that the characteristics of nonprofit organizations vary in their reliance on a variety of revenue resources and governance arrangements, as well as in their diverse policy focus. They also provide an extensive and diverse set of services that supports the ideas and efforts of social entrepreneurs
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