A stochastic approximation scheme and convergence theorem for particle interactions with perfectly reflecting boundaries

We prove the existence of a solution to an equation governing the number density within a compact domain of a discrete particle system for a prescribed class of particle interactions taking into account the effects of the diffusion and drift of the set of particles. Each particle carries a number of internal coordinates which may evolve continuously in time, determined by what we will refer to as the internal drift, or discretely via the interaction kernels. Perfectly reflecting boundary conditions are imposed on the system and all the processes may be spatially and temporally inhomogeneous. We use a relative compactness argument to construct a sequence of measures that converge weakly to a solution of the governing equation. Since the proof of existence is a constructive one, it provides a stochastic approximation scheme that can be used for the numerical study of molecular dynamics.Comment: 43 page

Trends in AFDC Participation Rates: The Implications for Welfare Reform

Congress justified the recent reform of federal welfare policy in part by citing the increase in the AFDC caseload since the late 1960s. The caseload, i.e., the number of families using AFDC, is determined by the number of families eligible to participate and by the proportion of these families who use the program. Yet the debate over reforming welfare rarely paid attention to the latter—the participation rates among female heads of families. While the number of cases changed little during the early to mid-1980s, the percentage of families with single female heads who used AFDC declined. During the late 1980s and early 1990s, both caseloads and participation rates increased. This paper documents the changes in participation rates since the mid-1980s, racial and ethnic differences in participation rates, and factors that might be associated with these changes. The only major trend that consistently parallels the changes in participation rates is the trend in unemployment. Existing data do not permit us to conclude that unemployment is the major determinant of participation rates. If unemployment drives participation rates, however, the recent changes in welfare legislation may create serious problems for many female heads of families in periods of high unemployment.

Electroweak precision measurements and collider probes of the Standard Model with large extra dimensions

The elementary particles of the Standard Model may live in more than 3+1 dimensions. We study the consequences of large compactified dimensions on scattering and decay observables at high-energy colliders. Our analysis includes global fits to electroweak precision data, indirect tests at high-energy electron-positron colliders (LEP2 and NLC), and direct probes of the Kaluza-Klein resonances at hadron colliders (Tevatron and LHC). The present limits depend sensitively on the Higgs sector, both the mass of the Higgs boson and how many dimensions it feels. If the Higgs boson is trapped on a 3+1 dimensional wall with the fermions, large Higgs masses (up to 500 GeV) and relatively light Kaluza-Klein mass scales (less than 4 TeV) can provide a good fit to precision data. That is, a light Higgs boson is not necessary to fit the electroweak precision data, as it is in the Standard Model. If the Higgs boson propagates in higher dimensions, precision data prefer a light Higgs boson (less than 260 GeV), and a higher compactification scale (greater than 3.8 TeV). Future colliders can probe much larger scales. For example, a 1.5 TeV electron-positron linear collider can indirectly discover Kaluza-Klein excitations up to 31 TeV if 500 fb^-1 integrated luminosity is obtained.Comment: 29 pages, LaTe

Shock-operated valve would automatically protect fluid systems

Glandless valve shuts down high-pressure fluid systems when severe shock from an explosion or earthquake occurs. The valve uses a pendulum to support the valve closure plug in the open position. When jarred, the valve body is moved relative to the pendulum and the plug support is displaced, allowing the plug to seat and be held by spring pressure

Life science payloads planning study

Preferred approaches and procedures were defined for integrating the space shuttle life sciences payload from experiment solicitation through final data dissemination at mission completion. The payloads operations plan was refined and expended to include current information. The NASA-JSC facility accommodations were assessed, and modifications recommended to improve payload processing capability. Standard format worksheets were developed to permit rapid location of experiment requirements and a Spacelab mission handbook was developed to assist potential life sciences investigators at academic, industrial, health research, and NASA centers. Practical, cost effective methods were determined for accommodating various categories of live specimens during all mission phases

Older women as occupational beings: exploring the meanings of occupations within the home environment for older women living alone

There is a discrepancy between the life expectancy of men and women of approximately two and a half years (Taylor Nelson Sofres 2014). This suggests that women are likely to spend a period of time in the latter years of their life living alone. It is anticipated that this will lead to a unique experience of later life for women, which to date has received little attention. This study is concerned with exploring the experience of living alone for 11 women aged 70-80 years from the South East of England. A particular emphasis is placed upon the experience of being an older woman, the activities that they engage in when they are at home alone, and the environment of home as a place for occupational engagement. Influenced by interpretive phenomenology and feminist principles, this study focuses on capturing the lived experiences of the 11 women in their own images and words. To achieve this, the methods of unstructured interviews and photo-elicitation are used. The women in this study describe a predominantly positive experience of living alone in later life. They value being busy, engage in a range of meaningful activities, and maintain their independence in everyday life. They provide compelling evidence that later life is a time for self-growth and development. This appears to link to the decline in the gender related roles and occupations which are expected of them in later life. This indicates that it is essential to provide bespoke support to older women that focuses on prevention of future decline but in a way that values their ongoing abilities

Occupational therapy through a feminist lens

Presentation at the annual Royal College of Occupational Therapy conference