Evolution of Non-linear Fluctuations in Preheating after Inflation

We investigate the evolution of the non-linear long wavelength fluctuations during preheating after inflation. By using the separate universe approach, the temporal evolution of the power spectrum of the scalar fields and the curvature variable is obtained numerically. We found that the amplitude of the large scale fluctuations is suppressed after non-linear evolution during preheating.Comment: To be published in Class. Quantum Gra

Immunology: Investigations on the cell type responsible for the endometrial secretion of complement component 3 (C3)

It has been shown that and human endometria have the capacity to produce complement component 3 (C3). In rats, endometrial C3 is an oestrogen-dependent protein produced and secreted by glandular cells. The cell responsible for the synthesis and secretion of human endometrial C3 has not been clearly defined. Our study was aimed at answering this question. Samples of endometrium obtained from hysterectomies were either immunostained for C3 or digested with collagenase; then the stromal and glandular cells were separated and immunopurified (or not) with an antibody to CD45 coupled to magnetic beads to eliminate the endometrial lymphomyeloid cells. Cells were cultured for 2 weeks and C3 measured in the medium by an in-house radioimmunoassay. Glandular as well as stromal cells stained positively for C3 and released C3 in vitro. The release of C3 from both cell types could be inhibited by cycloheximide. Epithelial cells produced significantly more C3 than stromal cells, and endometrial C3 production was higher for both cell types when these were obtained from secretory as compared to proliferative endometria. Lymphomyeloid cells were possibly a source of C3 since after immunoadsorption of these cells, the remaining stromal or glandular cells produced significantly less C3. We conclude that endometrial stromal, glandular and lymphomyeloid cells all produce C

On generation of metric perturbations during preheating

We consider the generation of the scalar mode of the metric perturbations during preheating stage in a two field model with the potential $V(\phi, \chi)= {m^{2}\phi^{2}\over 2}+{g^{2}\phi^{2}\chi^{2}\over 2}$. We discuss two possible sources of such perturbations: a) due to the coupling between the perturbation of the matter field $\delta \chi$ and the background part of the matter field $\chi_{0}(t)$, b) due to non-linear fluctuations in a condensate of ``particles'' of the field $\chi$. Both types of the metric perturbations are assumed to be small, and estimated using the linear theory of the metric perturbations. We estimate analytically the upper limit of the amplitude of the metric perturbations for all scales in the limit of so-called broad resonance, and show that the large scale metric perturbations are very small, and taking them into account does not influence the standard picture of the production of the metric perturbations in inflationary scenario.Comment: This version is to be published in PRD, new references added and typos correcte

Entanglement swapping with photons generated on-demand by a quantum dot

Photonic entanglement swapping, the procedure of entangling photons without any direct interaction, is a fundamental test of quantum mechanics and an essential resource to the realization of quantum networks. Probabilistic sources of non-classical light can be used for entanglement swapping, but quantum communication technologies with device-independent functionalities demand for push-button operation that, in principle, can be implemented using single quantum emitters. This, however, turned out to be an extraordinary challenge due to the stringent requirements on the efficiency and purity of generation of entangled states. Here we tackle this challenge and show that pairs of polarization-entangled photons generated on-demand by a GaAs quantum dot can be used to successfully demonstrate all-photonic entanglement swapping. Moreover, we develop a theoretical model that provides quantitative insight on the critical figures of merit for the performance of the swapping procedure. This work shows that solid-state quantum emitters are mature for quantum networking and indicates a path for scaling up.Comment: The first four authors contributed equally to this work. 17 pages, 3 figure

Fast and simple epidemiological typing of Pseudomonas aeruginosa using the double-locus sequence typing (DLST) method

Although the molecular typing of Pseudomonas aeruginosa is important to understand the local epidemiology of this opportunistic pathogen, it remains challenging. Our aim was to develop a simple typing method based on the sequencing of two highly variable loci. Single-strand sequencing of three highly variable loci (ms172, ms217, and oprD) was performed on a collection of 282 isolates recovered between 1994 and 2007 (from patients and the environment). As expected, the resolution of each locus alone [number of types (NT) = 35-64; index of discrimination (ID) = 0.816-0.964] was lower than the combination of two loci (NT = 78-97; ID = 0.966-0.971). As each pairwise combination of loci gave similar results, we selected the most robust combination with ms172 [reverse; R] and ms217 [R] to constitute the double-locus sequence typing (DLST) scheme for P. aeruginosa. This combination gave: (i) a complete genotype for 276/282 isolates (typability of 98%), (ii) 86 different types, and (iii) an ID of 0.968. Analysis of multiple isolates from the same patients or taps showed that DLST genotypes are generally stable over a period of several months. The high typability, discriminatory power, and ease of use of the proposed DLST scheme makes it a method of choice for local epidemiological analyses of P. aeruginosa. Moreover, the possibility to give unambiguous definition of types allowed to develop an Internet database ( http://www.dlst.org ) accessible by all

Connecting Clump Sizes in Turbulent Disk Galaxies to Instability Theory

In this letter we study the mean sizes of Halpha clumps in turbulent disk galaxies relative to kinematics, gas fractions, and Toomre Q. We use 100~pc resolution HST images, IFU kinematics, and gas fractions of a sample of rare, nearby turbulent disks with properties closely matched to z~1.5-2 main-sequence galaxies (the DYNAMO sample). We find linear correlations of normalized mean clump sizes with both the gas fraction and the velocity dispersion-to-rotation velocity ratio of the host galaxy. We show that these correlations are consistent with predictions derived from a model of instabilities in a self-gravitating disk (the so-called "violent disk instability model"). We also observe, using a two-fluid model for Q, a correlation between the size of clumps and self-gravity driven unstable regions. These results are most consistent with the hypothesis that massive star forming clumps in turbulent disks are the result of instabilities in self-gravitating gas-rich disks, and therefore provide a direct connection between resolved clump sizes and this in situ mechanism.Comment: Accepted to Apj Letter

Is sexual contact with sex workers important in driving the HIV epidemic among men in rural Zimbabwe?

OBJECTIVE: To establish the importance of commercial sex in driving the HIV epidemic in the general population by determining risk factors for HIV infection among male mine and farm workers and estimating the fraction of prevalent HIV infections attributable to sexual contact with sex workers (SWs). SETTING: Five commercial farms and 2 mines in Mashonaland West, Zimbabwe. METHODS: A cross-sectional interviewer-administered questionnaire and urine survey of 1405 male workers. Urine samples were tested for HIV antibodies by a particle agglutination test and enzyme-linked immunosorbent assay and for Chlamydia trachomatis and Neisseria gonorrhoeae using a polymerase chain reaction assay. RESULTS: The overall prevalence of HIV antibodies was 27.3% (95% confidence interval [CI]: 24.8 to 29.5), that of C. trachomatis was 1.5% (95% CI: 1.0 to 2.1), and that of N. gonorrhoeae was 0.5% (95% CI: 0.1 to 0.9). A total of 48.4% (95% CI: 45.8 to 51.0) of men reported ever having had sexual contact with an SW, and 29.3% (95% CI: 26.9 to 31.7) reported contact in the past year. HIV was more common among men who reported SW contact on univariate (1.9% [95% CI: 1.5 to 2.4]) and multivariate (1.4% [95% CI: 1.0 to 1.8]) analysis after adjusting for confounding. HIV was also strongly associated with self-reported genital ulceration in the previous 6 months (adjusted odds ratio [OR] = 3.1, 95% CI: 2.2 to 4.3). Genital ulceration and SW contact were highly correlated. A total of 19.6% of HIV infections in men could be attributed to ever having had sexual contact with an SW (95% CI: 10.8 to 27.6). CONCLUSIONS: An appreciable proportion of HIV infection in men is attributable to sexual contact with SWs. Consideration should be given to developing interventions that target male clients of SWs