19,411 research outputs found
Electronic charge density in helium in the first order shielding approximation
Electronic charge density for ground state of helium as function of nuclear charg
Some Remarks on the Use of the Variational Principle for the Second Order Energy
Approximate ground state wave function used in variational principle for second order energ
Lower bounds for several online variants of bin packing
We consider several previously studied online variants of bin packing and
prove new and improved lower bounds on the asymptotic competitive ratios for
them. For that, we use a method of fully adaptive constructions. In particular,
we improve the lower bound for the asymptotic competitive ratio of online
square packing significantly, raising it from roughly 1.68 to above 1.75.Comment: WAOA 201
Computer methods for the reduction, correlation and analysis of space battery test data, phase 2, part 1 Final report, 1 Nov. - 31 Dec. 1967
Computer methods for reduction, correlation, and analysis of space battery test dat
Photovoltaic effect in ferroelectric ceramics
The ceramic structure was simulated in a form that is more tractable to correlation between experiment and theory. Single crystals (of barium titanate) were fabricated in a simple corrugated structure in which the pedestals of the corrugation simulated the grain while the intervening cuts could be filled with materials simulating the grain boundaries. The observed photovoltages were extremely small (100 mv)
Health needs of the Roma population in the Czech and Slovak Republics.
In the growing literature on the human rights of Roma people in Central Europe, their relatively poor health status is often mentioned. However, little concrete information exists about the contemporary health status of the Roma in this region. We sought information on the health of the Roma in two of countries with significant Roma minorities, the Czech and Slovak Republics, by means of systematic searches for literature on the health of Roma people published in Czech or Slovak or by authors from the two countries. Published research on health of the Roma population is sparse. The topics that have received attention suggest a focus on concepts of contagion or social Darwinism, indicating a greater concern with the health needs of the majority populations with which they live. What limited evidence exists indicates that the health needs of the Roma population are considerable. With very few exceptions, the health status of Roma is worse than that of non-Roma population in both countries. The burden of communicable disease among Roma is high and diseases associated with poor hygiene seem to be particularly important. Evidence on health care suggests poor communication between Roma and health workers and low uptake of preventative care. The health needs of Roma lack visibility, not only because of the absence of research but also the absence of advocacy on their behalf. Since 1989, Czech and Slovak researchers have largely turned away from health research on particular ethnic groups. This probably reflects a growing sensitivity about stigmatising Roma, but it also makes it difficult to know how their circumstances might be improved. There is a need for further research into the health of Roma people with particular emphasis on non-communicable disease and for interventions that would improve their health
Energy Density-Flux Correlations in an Unusual Quantum State and in the Vacuum
In this paper we consider the question of the degree to which negative and
positive energy are intertwined. We examine in more detail a previously studied
quantum state of the massless minimally coupled scalar field, which we call a
``Helfer state''. This is a state in which the energy density can be made
arbitrarily negative over an arbitrarily large region of space, but only at one
instant in time. In the Helfer state, the negative energy density is
accompanied by rapidly time-varying energy fluxes. It is the latter feature
which allows the quantum inequalities, bounds which restrict the magnitude and
duration of negative energy, to hold for this class of states. An observer who
initially passes through the negative energy region will quickly encounter
fluxes of positive energy which subsequently enter the region. We examine in
detail the correlation between the energy density and flux in the Helfer state
in terms of their expectation values. We then study the correlation function
between energy density and flux in the Minkowski vacuum state, for a massless
minimally coupled scalar field in both two and four dimensions. In this latter
analysis we examine correlation functions rather than expectation values.
Remarkably, we see qualitatively similar behavior to that in the Helfer state.
More specifically, an initial negative energy vacuum fluctuation in some region
of space is correlated with a subsequent flux fluctuation of positive energy
into the region. We speculate that the mechanism which ensures that the quantum
inequalities hold in the Helfer state, as well as in other quantum states
associated with negative energy, is, at least in some sense, already
``encoded'' in the fluctuations of the vacuum.Comment: 21 pages, 7 figures; published version with typos corrected and one
added referenc
The Dual Feminisation of HIV/AIDS
This is an Accepted Manuscript of an article published by Taylor & Francis in Globalizations on 2011, available online: http://wwww.tandfonline.com/10.1080/14747731.2010.49302
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