62,815 research outputs found
The cosmological constant and the relaxed universe
We study the role of the cosmological constant (CC) as a component of dark
energy (DE). It is argued that the cosmological term is in general unavoidable
and it should not be ignored even when dynamical DE sources are considered.
From the theoretical point of view quantum zero-point energy and phase
transitions suggest a CC of large magnitude in contrast to its tiny observed
value. Simply relieving this disaccord with a counterterm requires extreme
fine-tuning which is referred to as the old CC problem. To avoid it, we discuss
some recent approaches for neutralising a large CC dynamically without adding a
fine-tuned counterterm. This can be realised by an effective DE component which
relaxes the cosmic expansion by counteracting the effect of the large CC.
Alternatively, a CC filter is constructed by modifying gravity to make it
insensitive to vacuum energy.Comment: 6 pages, no figures, based on a talk presented at PASCOS 201
Solar-wind control of the extent of planetary ionospheres
In our solar system there are at least four magnetic planets: Earth, Jupiter, Mercury, and Mars; while at least one planet, Venus, appears to be essentially nonmagnetic. The ionospheres of the magnetic planets are imbedded in their magnetosphere and thus shielded from the solar wind, whereas the ionosphere of Venus, at least, interacts directly with the solar wind. However, the solar wind interaction with the planetary environment, in both cases, affects the behavior of their ionospheres. The role the solar wind interaction plays in limiting the extent of the ionospheres of both magnetic and nonmagnetic planets is discussed
An electrically conductive thermal control surface for spacecraft encountering Low-Earth Orbit (LEO) atomic oxygen indium tin oxide-coated thermal blankets
An organic black thermal blanket material was coated with indium tin oxide (ITO) to prevent blanket degradation in the low Earth orbit (LEO) atomic oxygen environment. The blankets were designed for the Galileo spacecraft. Galileo was initially intended for space shuttle launch and would, therefore, have been exposed to atomic oxygen in LEO for between 10 and 25 hours. Two processes for depositing ITO are described. Thermooptical, electrical, and chemical properties of the ITO film are presented as a function of the deposition process. Results of exposure of the ITO film to atomic oxygen (from a shuttle flight) and radiation exposure (simulated Jovian environment) are also presented. It is shown that the ITO-protected thermal blankets would resist the anticipated LEO oxygen and Jovian radiation yet provide adequate thermooptical and electrical resistance. Reference is made to the ESA Ulysses spacecraft, which also used ITO protection on thermal control surfaces
The European Perspective on Women\u27s Leadership
The perspective of women in leadership positions is of particular impor- tance in Europe. It is a main subject in the areas of research and science. For example: At the University of Augsburg we conducted several studies of women\u27s leadership and the female academic career in view of gender is- sues such as gender within the family and in socialization. Furthermore we accomplished two gender mainstreaming studies with the focus on equity in several universities in Germany (Gender mainstreaming is a European law of 1997 and a political strategy of diversity management).
In this article we want to show the perspective on women\u27s leadership in Europe. Therefore we want to present the European data on the educational status of girls and women at schools and universities and in academic ca- reers. Data for Germany is presented as an example to provide evidence of some details. First, we want to point out four contradictions for women in the education system and concerning leadership positions. Second, data is discussed and some results of research explaining the data are given. Fi- nally, we present a European Program for the educational system to give women more chances: The so called Gender Mainstreaming Program
(1+1)-Dimensional SU(N) Static Sources in E and A Representations
Here is presented a detailed work on the (1+1) dimensional SU(N) Yang-Mills
theory with static sources. By studying the structure of the SU(N) group and of
the Gauss' law we construct in the electric representation the appropriate wave
functionals, which are simultaneously eigenstates of the Gauss' operator and of
the Hamiltonian. The Fourier transformation between the A- and the
E-representations connecting the Wilson line and a superposition of our
solutions is given.Comment: 10 pages, no figures, REVTEX, as in Phys. Rev.
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