Gravitational lensing, memory and the Penrose limit

In this paper, we discuss the gravitational field of ultrarelativistic extended spinning objects. For this purpose, we use a solution of the linearized gravitational equations obtained in the frame where such an object is translationally at rest, and boost this solution close to the speed of light. In order to obtain a regular limiting metric for non-spinning matter, it is sufficient to keep the energy of the boosted body fixed. This process is known as the Penrose limit. We demonstrate that in the presence of rotation, an additional rescaling is required for the angular momentum density components in the directions orthogonal to the boost. As a result of the Lorentz contraction, the thickness of the body in the direction of the boost shrinks. The body takes the form of a pancake, and its gravitational field is localized in the null plane. We discuss light and particle scattering in this gravitational field, and calculate the scattering parameters associated with the gravitational memory effect. We also show that by taking the inverse of the Penrose transform, one can use the obtained scattering map to study the gravitational lensing effect in the rest frame of a massive spinning object.Comment: 14 pages, 5 figures. 2 new references are adde

Chiral anomalies in black hole spacetimes

We study the properties of chiral anomalies in a wide class of spacetimes which possess a principal Killing-Yano tensor. This class includes metrics of charged rotating black holes as a special physically important case. The spacetimes which admit a principal Killing-Yano tensor possess a number of remarkable properties. In particular, such spacetimes have two commuting Killing vectors and a Killing tensor responsible for their hidden symmetries. We calculate the gravitational and electromagnetic contributions to the axial anomaly currents in the spacetime of a charged rotating black hole, and demonstrate that the equation for the chiral anomaly current has special solutions which respect both explicit and hidden symmetries. Two of these solutions have the form of currents propagating along two principal null directions, which are null eigenvectors of the Riemann tensor. These solutions describe chiral currents for the incoming and outgoing polarization fluxes. It is demonstrated that these principal chiral currents can be written explicitly in the form which contains the off-shell metric coefficients and their derivatives. We discuss conditions where the principle chiral anomaly current is regular at the horizon and the axes of symmetry. We demonstrate that for states where the current vanishes at the past horizon and at the past null infinity, there exist chirality fluxes at both the future horizon and future infinity. The latter is directly related to the polarization asymmetry of Hawking radiation for massless spinning particles. We also calculate the Chern-Simons currents for both gravitational and electromagnetic chiral anomalies in the black hole spacetime, and discuss the properties of the chirality fluxes associated with these currents.Comment: 20 pages, 9 figures, references adde

RAPD typing of Klebsiella pneumoniae, Klebsiella oxytoca, Serratia marcescens and Pseudomonas aeruginosa isolates using standardized reagents

ObjectiveTo perform quality assessment of standardized random amplified polymorphic DNA (RAPD) analysis for epidemiologic typing of Klebsiella pneumoniae, K. oxytoca, Serratia marcescens and Pseudomonas aeruginosa.MethodsThirty K. pneumoniae, 15 K. oxytoca, 30 S. marcescens and 33 P. aeruginosa epidemiologically unrelated isolates and four collections of clinically related isolates of each species were included in the study. RAPD analysis was performed using Ready-To-Go RAPD Analysis beads with primer ERIC-1R and Ready-To-Go primer 2 for K. pneumoniae and K. oxytoca, primer set ERIC-2/1026 and Ready-To-Go primer 2 for S. marcescens, and primers D-10514 and D-14306 for P. aeruginosa.ResultsAll epidemiologically unrelated K. pneumoniae and K. oxytoca isolates were distinguished. Twenty-nine types were distinguished among the 30 unrelated S. marcescens isolates and 32 types among the 33 unrelated P. aeruginosa isolates. Indistinguishable banding patterns were obtained in repeated analyses of two isolates and from 11 serial subcultures of three isolates of each species included in the study. The RAPD data from the clinically related isolates correlated with the epidemiologic origin of the isolates.ConclusionsThe use of Ready-To-Go RAPD Analysis beads resulted in reproducible and stable banding patterns with a high discriminatory capacity, and the RAPD typing results corresponded with the epidemiologic origin of the isolates

Two Years’ Prospective Collection of Molecular and Epidemiological Data Shows Limited Spread of Hepatitis A Virus outside Risk Groups in Amsterdam, 2000–2002

We performed a viral sequencing study on samples representing all reported primary cases of acute hepatitis A virus (HAV) infection reported for 2 years in Amsterdam. Two regions of HAV RNA were amplified, sequenced, and used for phylogenetic analysis. Of 156 cases, strains of 104 isolates (66.6%) clustered into 3 genotypes: 1A, 1B, and 3. Two separate transmission circles occurred, without mutual interrelation. In genotype 1A, 4 clusters occurred in men having sex with men (MSM), and the fifth cluster was related to a virus from Morocco. In genotype 1B, 6 small clusters were directly related to the Moroccan virus. In genotype 3, strains were related to a virus from Pakistan. Our analysis indicates that, to stop transmission of HAV in Amsterdam, the entire MSM population and travelers to countries where HAV is endemic, especially children, should be vaccinated. Prevention strategies need not include the vaccination of all children living in Amsterda

Prevalence of plasmid-mediated AmpC in Enterobacteriaceae isolated from humans and from retail meat in Zagazig, Egypt

Abstract Background The objective of this study was to determine the prevalence of plasmid-mediated AmpC (pAmpC) among Enterobacteriaceae isolated from humans and from retail meat in Egypt. Methods Enterobacteriaceae were isolated from patients with suspected bloodstream infection, human fecal samples, retail chicken meat samples and retail sheep meat samples. All group I Enterobacteriaceae were analyzed for presence of pAmpC genes by PCR. Antibiotic susceptibility testing was performed in all pAmpC positive isolates, followed by phenotypic and genotypic ESBL and carbapenemase testing on indication. Results The prevalence of pAmpC among group I Enterobacteriaceae isolated from 225 patients with bloodstream infection was 5.6% [95%CI 2.2–13.4]. Among 100 patients with community-onset gastroenteritis the prevalence in fecal samples was 4.8% [95%CI 2.1–10.7]. The prevalence among 112 chicken carcasses and 100 sheep meat samples was 2.4% [95%CI 0.7–8.4] and 1.1% [95%CI 0.2–5.7], respectively. In half of the AmpC positive isolates we detected an ESBL gene and 2 isolates harbored a carbapenemase gene. In five isolates there was resistance to at least three important alternative antibiotic drugs. Conclusions We consider the prevalence of pAmpC in Egypt, as found in our study, moderately low. To follow future trends in prevalence of pAmpC worldwide, a standardized screening algorithm for the detection of pAmpC is needed

Spatiotemporal lipid profiling during early embryo development of Xenopus laevis using dynamic ToF-SIMS imaging

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging has been used for the direct analysis of single intact Xenopus laevis embryo surfaces, locating multiple lipids during fertilization and the early embryo development stages with subcellular lateral resolution (∼4 μm). The method avoids the complicated sample preparation for lipid analysis of the embryos, which requires selective chemical extraction of a pool of samples and chromatographic separation, while preserving the spatial distribution of biological species. The results show ToF-SIMS is capable of profiling multiple components (e.g., glycerophosphocholine, SM, cholesterol, vitamin E, diacylglycerol, and triacylglycerol) in a single X. laevis embryo. We observe lipid remodeling during fertilization and early embryo development via time course sampling. The study also reveals the lipid distribution on the gamete fusion site. The methodology used in the study opens the possibility of studying developmental biology using high resolution imaging MS and of understanding the functional role of the biological molecules. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc