968 research outputs found
Gauged motion in general relativity and in Kaluza-Klein theories
In a recent paper [1] a new generalization of the Killing motion, the {\it
gauged motion}, has been introduced for stationary spacetimes where it was
shown that the physical symmetries of such spacetimes are well described
through this new symmetry. In this article after a more detailed study in the
stationary case we present the definition of gauged motion for general
spacetimes. The definition is based on the gauged Lie derivative induced by a
threading family of observers and the relevant reparametrization invariance. We
also extend the gauged motion to the case of Kaluza-Klein theories.Comment: 42 pages, revised version, typos correction along with some minor
changes, Revtex forma
The role of nicotinamide in acne treatment
Safe and effective treatment options for acne vulgaris are needed to address side effects and increasing rates of antibiotic resistance from current treatments. Nicotinamide is a vitamin with potent antiâ inflammatory properties that could offer a potential treatment option. We aim to summarize the relevant literature on the role of nicotinamide in acne vulgaris and discuss the next steps necessary to move this approach into clinical practice. We searched PubMed for clinical studies using nicotinamide for treatment of acne vulgaris. We summarized the 10 studies that met our search criteria. Six of eight studies using topical nicotinamide led to a significant reduction in acne compared with the patient’s baseline or performed similarly to another standardâ ofâ care acne treatment. Both studies using an oral supplement containing nicotinamide resulted in a significant reduction in acne compared with baseline. No major adverse side effects were noted. Our review suggests that topical and oral nicotinamide has an unclear effect on acne vulgaris due to the limited nature of the available literature. Additional studies are needed comparing nicotinamide to other firstâ line acne treatments and evaluating the efficacy and side effect profile of nicotinamide over an extended period of time.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138875/1/dth12481_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138875/2/dth12481.pd
Electromagnetic waves in NUT space: Solutions to the Maxwell equations
In this paper, using the Newman-Penrose formalism, we find the Maxwell
equations in NUT space and after separation into angular and radial components
solve them analytically. All the angular equations are solved in terms of
Jaccobi polynomials. The radial equations are transformed into Hypergeometric
and Heun's equations with the right hand sides including terms of different
order in the frequency of the perturbation which allow solutions in the
expansion of this parameter.Comment: 19 pages, Revtex format, Minor changes including an extention of the
discussion and typos correction, (Extended version of the article presented
to the GR16 conference, July 15-21 2001, Durban, South Africa
Classical Monopoles: Newton, NUT-space, gravomagnetic lensing and atomic spectra
Stimulated by a scholium in Newton's Principia we find some beautiful results
in classical mechanics which can be interpreted in terms of the orbits in the
field of a mass endowed with a gravomagnetic monopole. All the orbits lie on
cones! When the cones are slit open and flattened the orbits are exactly the
ellipses and hyperbolae that one would have obtained without the gravomagnetic
monopole.
The beauty and simplicity of these results has led us to explore the similar
problems in Atomic Physics when the nuclei have an added Dirac magnetic
monopole. These problems have been explored by others and we sketch the
derivations and give details of the predicted spectrum of monopolar hydrogen.
Finally we return to gravomagnetic monopoles in general relativity. We
explain why NUT space has a non-spherical metric although NUT space itself is
the spherical space-time of a mass with a gravomagnetic monopole. We
demonstrate that all geodesics in NUT space lie on cones and use this result to
study the gravitational lensing by bodies with gravomagnetic monopoles.
We remark that just as electromagnetism would have to be extended beyond
Maxwell's equations to allow for magnetic monopoles and their currents so
general relativity would have to be extended to allow torsion for general
distributions of gravomagnetic monopoles and their currents. Of course if
monopoles were never discovered then it would be a triumph for both Maxwellian
Electromagnetism and General Relativity as they stand!Comment: 39 pages, 9 figures and 2 tables available on request from the
author
Characterisation of the differential expression of marker antigens by normal and malignant endometrial epithelium.
In order to examine the production of marker proteins, a reproducible method has been established for culturing purified epithelial cells from normal and malignant endometrium. We have examined the differential expression of secretory proteins using immunohistochemistry in frozen tissue sections, immunocytochemistry in cell cultures derived from the same specimens and protein assays on the culture supernatants. Placental protein 14 (PP14) was produced by normal premenopausal epithelium but not by the post-menopausal or malignant endometrial epithelium. In contrast, placental alkaline phosphatase (PLAP) was produced by endometrial cancers and the endometrial adenocarcinoma-derived cell line Ishikawa, but not by the normal endometrial epithelium. Other markers such as CA-125, which was produced by both normal and malignant endometrium but not by the cell line, and human chorionic gonadotrophin (beta-hCG), which was produced by Ishikawa cells but not by any of the fresh tissues, were less cancer specific. Placental alkaline phosphatase is a direct product of endometrial cancers that can be readily assayed in serum using this two-site assay to test its clinical usefulness in monitoring patients at risk for endometrial cancer
Evolution of the Magnetized, Neutrino-Cooled Accretion Disk in the Aftermath of a Black Hole Neutron Star Binary Merger
Black hole-torus systems from compact binary mergers are possible engines for
gamma-ray bursts (GRBs). During the early evolution of the post-merger remnant,
the state of the torus is determined by a combination of neutrino cooling and
magnetically-driven heating processes, so realistic models must include both
effects. In this paper, we study the post-merger evolution of a magnetized
black hole-neutron star binary system using the Spectral Einstein Code (SpEC)
from an initial post-merger state provided by previous numerical relativity
simulations. We use a finite-temperature nuclear equation of state and
incorporate neutrino effects in a leakage approximation. To achieve the needed
accuracy, we introduce improvements to SpEC's implementation of
general-relativistic magnetohydrodynamics (MHD), including the use of
cubed-sphere multipatch grids and an improved method for dealing with
supersonic accretion flows where primitive variable recovery is difficult. We
find that a seed magnetic field triggers a sustained source of heating, but its
thermal effects are largely cancelled by the accretion and spreading of the
torus from MHD-related angular momentum transport. The neutrino luminosity
peaks at the start of the simulation, and then drops significantly over the
first 20\,ms but in roughly the same way for magnetized and nonmagnetized
disks. The heating rate and disk's luminosity decrease much more slowly
thereafter. These features of the evolution are insensitive to grid structure
and resolution, formulation of the MHD equations, and seed field strength,
although turbulent effects are not fully convergedComment: 17 pages, 18 figure
Ultra-Rare Variants Identify Biological Pathways and Candidate Genes in the Pathobiology of Non-Syndromic Cleft Palate Only
: In recent decades, many efforts have been made to elucidate the genetic causes of non-syndromic cleft palate (nsCPO), a complex congenital disease caused by the interaction of several genetic and environmental factors. Since genome-wide association studies have evidenced a minor contribution of common polymorphisms in nsCPO inheritance, we used whole exome sequencing data to explore the role of ultra-rare variants in this study. In a cohort of 35 nsCPO cases and 38 controls, we performed a gene set enrichment analysis (GSEA) and a hypergeometric test for assessing significant overlap between genes implicated in nsCPO pathobiology and genes enriched in ultra-rare variants in our cohort. GSEA highlighted an enrichment of ultra-rare variants in genes principally belonging to cytoskeletal protein binding pathway (Probability Density Function corrected p-value = 1.57 × 10-4); protein-containing complex binding pathway (p-value = 1.06 × 10-2); cell adhesion molecule binding pathway (p-value = 1.24 × 10-2); ECM-receptor interaction pathway (p-value = 1.69 × 10-2); and in the Integrin signaling pathway (p-value = 1.28 × 10-2). Two genes implicated in nsCPO pathobiology, namely COL2A1 and GLI3, ranked among the genes (n = 34) with nominal enrichment in the ultra-rare variant collapsing analysis (Fisher's exact test p-value < 0.05). These genes were also part of an independent list of genes highly relevant to nsCPO biology (n = 25). Significant overlap between the two sets of genes (hypergeometric test p-value = 5.86 × 10-3) indicated that enriched genes are likely to be implicated in physiological palate development and/or the pathological processes of oral clefting. In conclusion, ultra-rare variants collectively impinge on biological pathways crucial to nsCPO pathobiology and point to candidate genes that may contribute to the individual risk of disease. Sequencing can be an effective approach to identify candidate genes and pathways for nsCPO
Hydrogen atom in phase space. The Kirkwood-Rihaczek representation
We present a phase-space representation of the hydrogen atom using the
Kirkwood-Rikaczek distribution function. This distribution allows us to obtain
analytical results, which is quite unique because an exact analytical form of
the Wigner functions corresponding to the atom states is not known. We show how
the Kirkwood-Rihaczek distribution reflects properties of the hydrogen atom
wave functions in position and momentum representations.Comment: 5 pages (and 5 figures
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