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

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

Defective expression of basement membrane-associated C3d,g in papulonodular basal cell carcinomas

AbstractRecent studies in our laboratory have shown that C3d,g, a 41,000-Da fragment of the third component of complement, is present along the base of the lamina densa and in the sublamina densa region of normal human epidermal basement membrane, but absent from the skin of a patient with congenital C3 deficiency. In studies of human skin, papulonodular basal cell carcinomas have served as a useful model for the investigation of various basement membrane antigens and matrix proteins. To further investigate the presence of C3d,g within epidermal basement membrane as well as examine its relationship with other known basement membrane constituents, we have analyzed serial sections of ten papulonodular basal cell carcinomas by light and immunofluorescence microscopy. In these studies, C3d,g was either absent (N = 9) or minimumly detectable (N = 1) in tumor nest basement membranes. While bullous pemphigoid and KF-1 antigens were absent (N = 6 and N = 3, respectively) or significantly decreased (N = 4 and N = 7, respectively), epidermolysis bullosa acquisita antigen was routinely present though somewhat (N = 3) or moderately decreased (N = 3).Laminin and type IV collagen were expressed normally in all tumor nest basement membranes. All constituents, including C3d,g, were present in adjacent normal epidermal basement membrane of these tumor samples. This study has demonstrated antigenic alterations within each ultrastructural subregion of papulonodular basal cell carcinoma tumor nest basement membranes by identifying the virtual absence of C3d,g (sublamina densa) as well as a significant reduction in KF-1 (lamina densa) and bullous pemphigoid (lamina lucida) antigens. Moreover, the presence of laminin, type IV collagen, and epidermolysis bullosa acquisita antigen in tumor nest basement membranes suggests that these particular constituents neither cleave C3 nor act as essential binding sites for passive incorporation of this complement component in epidermal basement membrane. These studies give additional support to the hypothesis that C3d,g is a previously unrecognized constituent of normal epidermal basement membrane and does not represent passive incorporation of circulating C3 at this site in human skin

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

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

HYPERPHOSPHATEMIA IN END STAGE RENAL DISEASE: PREVALENCE AND PATIENTS CHARACTERISTICS OF MULTIETHNIC POPULATION OF UNITED ARAB EMIRATES

Objective: Hyperphosphatemia is significantly associated with increased mortality among end stage renal disease (ESRD) patients on hemodialysis. There is paucity of data on hyperphosphatemia in ESRD patients of the multiethnic population of United Arab Emirates (UAE). The study aimed to investigate the prevalence and characteristics of hyperphosphatemia in ESRD patients of the multiethnic population of UAE undergoing maintenance hemodialysis.Methods: Adults ESRD patients undergoing maintenance hemodialysis for more than six months at the study site were included. Demographic, clinical and biological data of the patients were collected. Patient characteristics were compared as per the serum phosphate level, between patients with or without hyperphosphatemia. Univariate and multivariate logistic regression analyses were carried out to identify the predictors of hyperphosphatemia.Results: Hyperphosphatemia was present in 73.8% of the study population, while 31.3% presented with high calcium-phosphate product. Univariate logistic analysis revealed that hyperphosphatemia was inversely correlated with age, hemoglobin, serum calcium, and hypertensive nephropathy as cause of renal disease, and positively correlated with female gender, expatriate status, body mass index (BMI), higher number of comorbidities, calcium-phosphate product and parathyroid hormone (PTH). Multivariate logistic regression model revealed that only age, BMI, hemoglobin and PTH independently correlated with hyperphosphatemia.Conclusion: We report a high prevalence of hyperphosphatemia in multiethnic study population undergoing maintenance hemodialysis at a secondary care hospital in UAE. In this study population, only age, BMI, hemoglobin and PTH were identified as independent predictors of hyperphosphatemia

Improvements in selectivity and stability of Rh catalysts modified by SnBu₄. dehydrogenation of isobutane to isobutene

RhSn/SiO2 bimetallic catalysts prepared via an organometallic route have proved to be very active and selective toward several hydrogenation reactions. In this work these catalysts were studied for the dehydrogenation of isobutane to isobutene. It was found that Rh/SiO2 monometallic catalysts had a null selectivity to isobutene, and this selectivity increased up to more than 90% after the addition of tin, using SnBu4 as precursor.Facultad de Ciencias Exacta

Dynamics of a small neutrally buoyant sphere in a fluid and targeting in Hamiltonian systems

We show that, even in the most favorable case, the motion of a small spherical tracer suspended in a fluid of the same density may differ from the corresponding motion of an ideal passive particle. We demonstrate furthermore how its dynamics may be applied to target trajectories in Hamiltonian systems.Comment: See home page http://lec.ugr.es/~julya

Development and evaluation of double locus sequence typing for molecular epidemiological investigations of Clostridium difficile.

Despite the development of novel typing methods based on whole genome sequencing, most laboratories still rely on classical molecular methods for outbreak investigation or surveillance. Reference methods for Clostridium difficile include ribotyping and pulsed-field gel electrophoresis, which are band-comparing methods often difficult to establish and which require reference strain collections. Here, we present the double locus sequence typing (DLST) scheme as a tool to analyse C. difficile isolates. Using a collection of clinical C. difficile isolates recovered during a 1-year period, we evaluated the performance of DLST and compared the results to multilocus sequence typing (MLST), a sequence-based method that has been used to study the structure of bacterial populations and highlight major clones. DLST had a higher discriminatory power compared to MLST (Simpson's index of diversity of 0.979 versus 0.965) and successfully identified all isolates of the study (100 % typeability). Previous studies showed that the discriminatory power of ribotyping was comparable to that of MLST; thus, DLST might be more discriminatory than ribotyping. DLST is easy to establish and provides several advantages, including absence of DNA extraction [polymerase chain reaction (PCR) is performed on colonies], no specific instrumentation, low cost and unambiguous definition of types. Moreover, the implementation of a DLST typing scheme on an Internet database, such as that previously done for Staphylococcus aureus and Pseudomonas aeruginosa ( http://www.dlst.org ), will allow users to easily obtain the DLST type by submitting directly sequencing files and will avoid problems associated with multiple databases