Empty singularities in higher-dimensional Gravity

We study the exact solution of Einstein's field equations consisting of a ($n+2$)-dimensional static and hyperplane symmetric thick slice of matter, with constant and positive energy density $\rho$ and thickness $d$, surrounded by two different vacua. We explicitly write down the pressure and the external gravitational fields in terms of $\rho$ and $d$, the pressure is positive and bounded, presenting a maximum at an asymmetrical position. And if $\sqrt{\rho}\,d$ is small enough, the dominant energy condition is satisfied all over the spacetime. We find that this solution presents many interesting features. In particular, it has an empty singular boundary in one of the vacua.Comment: 13 page

A survey of diseases among 100 free-ranging baboons (Papio ursinus) from the Kruger National Park

The pathological and parasitological findings from 100 free-ranging chacma baboons are described. One of the most striking discoveries was a heretofore unknown coccidian parasite, Isospora papionis, and even more important than its presence in the small intestine was its occurrence in skeletal muscles. Serological and histopathological evidence of toxoplasmosis was found in several animals. Other previously unknown parasites encountered included two mites- Rhinophaga elongata, an unusually long mite that produced small granulomas in the nasal mucosae, and Pneumonyssus vocalis, a mite found in the laryngeal ventricles. A new species of filarid, Tetrapetalonema papionis was found in the subcutis and intermuscular fascia. New records for the chacma baboon of known parasites were R. papionis, a mite found only in the maxillary recess, where it stimulated a polyplike growth, and, in the skeletal muscles, cysticerci of Taenia crocutae, a tapeworm of hyenas (Crocuta crocuta and Hyaena brunnea). Apart from the pathological changes associated with the above parasites, another important finding was numerous cases of "capture myopathy", a syndrome that resembles Meyer-Betz disease of man. One of the most severe diseases encountered was pulmonary acariasis (P. mossambicensis), which at times caused large foci of supportive pneumonia and diffuse pleuritis. The mite pigment was also found in draining lymph nodes. The most serious diseases of the liver were cytomegaly, which was similar to that produced by mycotoxins in other animal species, multiple granulomatous foci caused by Hepatocystis simiae and microgranulomas caused by ova of Schistosoma mattheei. Adult schistosomes were also found in the mesenteric vessels. The most important lesion in the central nervous system was an axonal hamartoma, which was found in two cases and involved a large portion of the brain stem. Also of note were a meningioma in the falx cerebelli, a few examples of non-suppurativc encephalitis and several cases in which neurons in the medulla oblongata had been replaced by a globular eosinophilic mass. Other tumours found were a fibroma in the subcutis of the face and a basal cell carcinoma in the skin on the back. Both were of local importance only. Developmental anomalies included an accessory spleen, ectopic pancreatic tissue in the duodenum, thymic tissue embedded in the thyroid and parathyroid and microcysts in the thymus, parathyroid and adenohypophysis. Arteriosclerosis of limited severity was found in the aorta and coronary and renal arteries of many of the older baboons (males and females). Another vascular change related to previous pregnancy was sclerosis of the ovarian and uterine vessels. Degenerative changes were found in the central arteries of germinal follicles in various lymph nodes and the spleen. Other noteworthy findings included the presence of spargana in the skeletal muscles; ranula formation of the ducts of the glands of Ebner; para-ovarian crystals; large intranuclear inclusions in the submandibular salivary gland compatible with those produced by cytomegalovirus and intranuclear inclusions in the epididymis. Various gastro-intestinal parasites were found and their corresponding lesions are described. Selected bacterial studies for shigellae and salmonellae were negative, as were intradermal tests for tuberculosis and serological tests for leptospirosis and brucellosis. The brain, heart, spleen, liver, lungs and kidneys were mass measured and were compared to the body mass. In all age groups the heart varied the least when expressed as percent body mass. The brain was the most variable in this regard but changed the least in total mass.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Minority carrier lifetime in silicon photovoltaics : the effect of oxygen precipitation

Single-crystal Czochralski silicon used for photovoltaics is typically supersaturated with interstitial oxygen at temperatures just below the melting point. Oxide precipitates therefore can form during ingot cooling and cell processing, and nucleation sites are typically vacancy-rich regions. Oxygen precipitation gives rise to recombination centres, which can reduce cell efficiencies by as much as 4% (absolute). We have studied the recombination behaviour in p-type and n-type monocrystalline silicon with a range of doping levels intentionally processed to contain oxide precipitates with a range of densities, sizes and morphologies. We analyse injection-dependent minority carrier lifetime measurements to give a full parameterisation of the recombination activity in terms of Shockley–Read–Hall statistics. We intentionally contaminate specimens with iron, and show recombination activity arises from iron segregated to oxide precipitates and surrounding defects. We find that phosphorus diffusion gettering reduces the recombination activity of the precipitates to some extent. We also find that bulk iron is preferentially gettered to the phosphorus diffused layer rather than to oxide precipitates

Influence of a Uniform Current on Collective Magnetization Dynamics in a Ferromagnetic Metal

We discuss the influence of a uniform current, $\vec{j}$, on the magnetization dynamics of a ferromagnetic metal. We find that the magnon energy $\epsilon(\vec{q})$ has a current-induced contribution proportional to $\vec{q}\cdot \vec{\cal J}$, where $\vec{\cal J}$ is the spin-current, and predict that collective dynamics will be more strongly damped at finite ${\vec j}$. We obtain similar results for models with and without local moment participation in the magnetic order. For transition metal ferromagnets, we estimate that the uniform magnetic state will be destabilized for $j \gtrsim 10^{9} {\rm A} {\rm cm}^{-2}$. We discuss the relationship of this effect to the spin-torque effects that alter magnetization dynamics in inhomogeneous magnetic systems.Comment: 12 pages, 2 figure

Measurements of 0.2 to 20 GeV/n cosmic-ray proton and helium spectra from 1997 through 2002 with the BESS spectrometer

We measured low energy cosmic-ray proton and helium spectra in the kinetic energy range 0.215 - 21.5 GeV/n at different solar activities during a period from 1997 to 2002. The observations were carried out with the BESS spectrometer launched on a balloon at Lynn Lake, Canada. A calculation for the correction of secondary particle backgrounds from the overlying atmosphere was improved by using the measured spectra at small atmospheric depths ranging from 5 through 37 g/cm^2. The uncertainties including statistical and systematic errors of the obtained spectra at the top of atmosphere are 5-7 % for protons and 6-9 % for helium nuclei in the energy range 0.5 - 5 GeV/n.Comment: 27 pages, 7 Tables, 9 figures, Submitted to Astroparticle Physic

International Trade and Investment Sanctions

The purpose of this paper is to clarify the theory of international economic sanctions and to provide estimates of the short-run economic impact on South Africa of externally imposed reductions of the imports and capital flows into that country. A macroeconomic picture of South Africa's "dependence" is drawn, and the economy's vulnerability in the short run is seen to be in its capacity to import, not in exports or capital flows. Trade and capital sanctions most clearly damage South Afnca's growth potential; the short-run impact is harder to quantify. A static linear programming model of the South African economy is constructed in an attempt at this quantification. This model estimates that small sanctions would have small impact—i.e., if imports were reduced by less than one-fourth, GDP would be cut by only about one half as large a percentage as imports. Larger import reductions cause greater damage. If imports were to be cut in half, not only would GDP be seriously reduced but massive unemployment and relocation of white labor would occur.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68182/2/10.1177_002200277902300401.pd

Measurement of cosmic-ray low-energy antiproton spectrum with the first BESS-Polar Antarctic flight

The BESS-Polar spectrometer had its first successful balloon flight over Antarctica in December 2004. During the 8.5-day long-duration flight, almost 0.9 billion events were recorded and 1,520 antiprotons were detected in the energy range 0.1-4.2 GeV. In this paper, we report the antiproton spectrum obtained, discuss the origin of cosmic-ray antiprotons, and use antiprotons to probe the effect of charge sign dependent drift in the solar modulation.Comment: 18 pages, 1 table, 5 figures, submitted to Physics Letters

Fractional Quantum Hall Effect via Holography: Chern-Simons, Edge States, and Hierarchy

We present three holographic constructions of fractional quantum Hall effect (FQHE) via string theory. The first model studies edge states in FQHE using supersymmetric domain walls in N=6 Chern-Simons theory. We show that D4-branes wrapped on CP^1 or D8-branes wrapped on CP^3 create edge states that shift the rank or the level of the gauge group, respectively. These holographic edge states correctly reproduce the Hall conductivity. The second model presents a holographic dual to the pure U(N)_k (Yang-Mills-)Chern-Simons theory based on a D3-D7 system. Its holography is equivalent to the level-rank duality, which enables us to compute the Hall conductivity and the topological entanglement entropy. The third model introduces the first string theory embedding of hierarchical FQHEs, using IIA string on C^2/Z_n.Comment: 36 pages, 6 figures; v2: with an improved derivation of Hall conductivity in section 3.2, typo corrections, and additional references; v3: explanations and comments adde

Understanding preventive behaviors among mid-Western African-American men: a pilot qualitative study of prostate screening

http://dx.doi.org/10.1016/j.jomh.2011.03.00

Corrections to flat-space particle dynamics arising from space granularity

The construction of effective Hamiltonians describing corrections to flat space particle dynamics arising from the granularity of space at very short distances is discussed in the framework of an heuristic approach to the semiclassical limit of loop quantum gravity. After some general motivation of the subject, a brief non-specialist introduction to the basic tools employed in the loop approach is presented. The heuristical semiclassical limit is subsequently defined and the application to the case of photons and spin 1/2 fermions is described. The resulting modified Maxwell and Dirac Hamiltonians, leading in particular to Planck scale corrections in the energy-momentum relations, are presented. Alternative interpretations of the results and their limitations, together with other approaches are briefly discussed along the text. Three topics related to the above methods are reviewed: (1) The determination of bounds to the Lorentz violating parameters in the fermionic sector, obtained from clock comparison experiments.(2) The calculation of radiative corrections in preferred frames associated to space granularity in the framework of a Yukawa model for the interactions and (3) The calculation of synchrotron radiation in the framework of the Myers-Pospelov effective theories describing Lorentz invariance violations, as well as a generalized approach to radiation in Planck scale modified electrodynamics. The above exploratory results show that quantum gravity phenomenology provides observational guidance in the construction of quantum gravity theories and opens up the possibility of probing Planck scale physics.Comment: 49 pages, 6 figures and 4 tables. Extended version of the talk given at the 339-th WE-Heraeus-Seminar: Special Relativity, will it survive the next 100 years?, Potsdam, february 200