15,958 research outputs found
Recent Studies of Nonequilibrium Flows at the Cornell Aeronautical Laboratory
Vibrational relaxation in supersonic nozzle diatomic gas flow, nonequilibrium effects in high enthalpy airflow over thick wedge flat plates, and reentry nonequilibrium flow field
Cosmological string models from Milne spaces and SL(2,Z) orbifold
The -dimensional Milne Universe with extra free directions is used to
construct simple FRW cosmological string models in four dimensions, describing
expansion in the presence of matter with , . We then
consider the n=2 case and make SL(2,Z) orbifold identifications. The model is
surprisingly related to the null orbifold with an extra reflection generator.
The study of the string spectrum involves the theory of harmonic functions in
the fundamental domain of SL(2,Z). In particular, from this theory one can
deduce a bound for the energy gap and the fact that there are an infinite
number of excitations with a finite degeneracy. We discuss the structure of
wave functions and give examples of physical winding states becoming light near
the singularity.Comment: 14 pages, harvma
Body image perception and body composition: assessment of perception inconsistency by a new index
BACKGROUND: A correct perception of the body image, as defined by comparison with actual anthropometric analyses, is crucial to ensure the best possible nutritional status of each individual. Bioimpedance analysis (BIA) represents a leading technique to assess body composition parameters and, in particular, the fat mass. This study examined the self-perception of body image at various levels of adiposity proposing a new index. METHODS: We investigated 487 young Italian adults (mean age of males: 21.9â±â2.4 years; mean age of females: 21.0â±â2.2 years). Each subject could choose, on the Contour Drawing Rating Scale, the silhouette that he/she considered most resembling his/her perceived body image as well as his/her ideal body image. On each subject, we performed anthropometric measurements and determined the values of Fat mass and Ășt with BIA. A new index, FAIFAT (Feel fat status minus Actual fat status Inconsistency), was developed to evaluate possible fat status perception inconsistencies by BIA. RESULTS: Based on ideal and feel body image comparison, women showed higher dissatisfaction than men and preferred slimmer silhouettes. FAIFAT values indicated that the fat status perception was correct in the majority of the examined individuals and only three subjects showed a serious misperception. CONCLUSIONS: Our findings suggest that FAIFAT is an appropriate index for assessing the perceived fat status from the body image when compared with data obtained by BIA. In a population, the use of this index will allow the correct identification of groups at risk for eating disorders
Model of black hole evolution
From the postulate that a black hole can be replaced by a boundary on the
apparent horizon with suitable boundary conditions, an unconventional scenario
for the evolution emerges. Only an insignificant fraction of energy of order
is radiated out. The outgoing wave carries a very small part of the
quantum mechanical information of the collapsed body, the bulk of the
information remaining in the final stable black hole geometry.Comment: 9 pages, harvmac, 3 figures, minor addition
Model of black hole evolution
From the postulate that a black hole can be replaced by a boundary on the
apparent horizon with suitable boundary conditions, an unconventional scenario
for the evolution emerges. Only an insignificant fraction of energy of order
is radiated out. The outgoing wave carries a very small part of the
quantum mechanical information of the collapsed body, the bulk of the
information remaining in the final stable black hole geometry.Comment: 9 pages, harvmac, 3 figures, minor addition
High quality superconducting niobium films produced by Ultra High Vacuum Cathodic Arc
The vacuum arc is a well-known technique to produce coating with enhanced
adhesion and film density. Many cathodic arc deposition systems are actually in
use in industry and research. They all work under (high) vacuum conditions in
which water vapor pressure is an important source of film contamination,
especially in the pulsed arc mode of operation. Here we present a Cathodic Arc
system working under Ultra High Vacuum conditions (UHVCA). UHVCA has been used
to produce ultra-pure niobium films with excellent structural and electrical
properties at a deposition temperature lower than 100oC. The UHVCA technique
therefore opens new perspectives for all applications requiring ultra-pure
films or, as in the case of Plasma Immersion Ion Implantation, ultra-pure
plasmas.Comment: submitted to AP
Student Newspapers at Public Colleges and Universities: Lessons from the United States
An on-campus activity of enduring interest in the United States that is present elsewhere in the English-speaking world, but that has yet to yield reported litigation or academic writing in Great Britain, concerns free speech issues associated with student newspapers in higher education. Student newspapers have long occupied a significant role in their dual functions of informing members of their campus communities and as preparation grounds for future journalists. Against this background, the remainder of this article is divided into three major sections. The first part examines the nature of student newspapers and related issues while the second examines key litigation involving these publications in public institutions; these parts of the article focus on state-funded institutions in the United States insofar as the protections afforded by the First Amendment with regard to freedom of speech and expression are inapplicable in non-public, or private, institutions where most rights are contractual in nature. The final portion of the article offers suggestions particularly for readers who work in and with tertiary institutions involving student journalists. This article rounds out with a brief conclusion
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