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

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

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

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

Active stabilization to prevent surge in centrifugal compression systems

This report documents an experimental and analytical study of the active stabilization of surge in a centrifugal engine. The aims of the research were to extend the operating range of a compressor as far as possible and to establish the theoretical framework for the active stabilization of surge from both an aerodynamic stability and a control theoretic perspective. In particular, much attention was paid to understanding the physical limitations of active stabilization and how they are influenced by control system design parameters. Previously developed linear models of actively stabilized compressors were extended to include such nonlinear phenomena as bounded actuation, bandwidth limits, and robustness criteria. This model was then used to systematically quantify the influence of sensor-actuator selection on system performance. Five different actuation schemes were considered along with four different sensors. Sensor-actuator choice was shown to have a profound effect on the performance of the stabilized compressor. The optimum choice was not unique, but rather shown to be a strong function of some of the non-dimensional parameters which characterize the compression system dynamics. Specifically, the utility of the concepts were shown to depend on the system compliance to inertia ratio ('B' parameter) and the local slope of the compressor speedline. In general, the most effective arrangements are ones in which the actuator is most closely coupled to the compressor, such as a close-coupled bleed valve inlet jet, rather than elsewhere in the flow train, such as a fuel flow modulator. The analytical model was used to explore the influence of control system bandwidth on control effectiveness. The relevant reference frequency was shown to be the compression system's Helmholtz frequency rather than the surge frequency. The analysis shows that control bandwidths of three to ten times the Helmholtz frequency are required for larger increases in the compressor flow range. This has important implications for implementation in gas turbine engines since the Helmholtz frequencies can be over 100 Hz, making actuator design extremely challenging

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

Some remarks on the sternheimer potential

Generalization of Sternheimer potential to include wave functions with spi

Adaptation to potassium

In vertebrates, the development of complex and efficient mechanisms for avoiding potassium intoxication might be predicted from a simple consideration of their chemical anatomy. The proper function of excitable membranes depends on a low concentration of potassium outside of the cell. On the other hand, potassium is the major ionic constituent of intracellular fluid; it therefore accompanies calories in almost every form of food. Animals that alternate starvation with periods of gorging themselves must therefore be able to adapt to sudden large exogenous loads of potassium in order to avoid potassium intoxication

Relating on-shell and off-shell formalism in perturbative quantum field theory

In the on-shell formalism (mostly used in perturbative quantum field theory) the entries of the time ordered product T are on-shell fields (i.e. the basic fields satisfy the free field equations). With that, (multi)linearity of T is incompatible with the Action Ward identity. This can be circumvented by using the off-shell formalism in which the entries of T are off-shell fields. To relate on- and off-shell formalism correctly, a map sigma from on-shell fields to off-shell fields was introduced axiomatically by Duetsch and Fredenhagen. In that paper it was shown that, in the case of one real scalar field in N=4 dimensional Minkowski space, these axioms have a unique solution. However, this solution was given there only recursively. We solve this recurrence relation and give a fully explicit expression for sigma in the cases of the scalar, Dirac and gauge fields for arbitrary values of the dimension N.Comment: The case of gauge fields was added. 16 page