Hepatitis C in hemodialysis centers of golestan province, northeast of Iran (2005)

Background and Aims: Nosocomial transmission of blood-borne pathogens is common in a dialysis setting. Hepatitis C virus (HCV) infection is a common problem that increases morbidity and mortality in hemodialysis patients. Blood transfusion and the duration of hemodialysis are the most important factors in HCV transmission. The aim of the study was to determine the incidence rate of HCV antibody in hemodialysis patients and its association with some factors. Methods: In this descriptive-analytical study, HCV antibody was measured in 93 hemodialysis patients in all hospitals affiliated to Golestan University of Medical Sciences. Standard infection prevention measures in hospital settings and dialysis units were performed including serologic testing for HCV antibody for every new patient in the dialysis unit as well as routine testing of all patients. Negative cases of hepatitis C antibody (confirmed with ELISA 2nd generation and RIBA II Immunoblot methods) were selected and followed for 18 months. Some predisposing factors such as transfusion, duration of hemodialysis, medical procedures including surgery, transplantation, invasive odontology, suspicious sexual contact, diagnostic or therapeutic manipulation, tattooing, and IV drug abuse, were registered and considered. Other rare procedures like acupuncture, manicure and pedicure blood brotherhood rituals, perinatal risk factors, common circumcision rituals and history of abortion were also considered. Ve used a tight control policy through the separation of the rooms within the unit, specific hemodialysis apparatus for suspicious patients and a separate staff caring for the patients. We maintained a low rate of staff turnover in dialysis units and tried to control hepatitis B viral infection. Results: Marital status and living area were significantly related to HCV antibody positivity. It means that more HCV antibody positive cases were observed in married people in urban areas. History of tattooing, medical procedures including surgery, transplantation, invasive odontology and IV drug usage were not significantly related to HCV antibody status. During the follow up, three cases (4.3%) converted to positive. There was a relationship between numbers of hemodialysis per week and HCV antibody positivity (P<0.001). Conclusions: Tight control of transmission routes and severe isolation policy in this study explains an almost ideal decrease in incidence rate of HCV antibody positivity. We suggest periodical screening programs (at least every 6 months) for blood samples that remain in the dialysis apparatus and all procedures used for hemodialysis in these specific patients to achieve a better infection control

Compensating Faraday depolarization by magnetic helicity in the solar corona

A turbulent dynamo in spherical geometry with an outer corona is simulated to study the sign of magnetic helicity in the outer parts. In agreement with earlier studies, the sign in the outer corona is found to be opposite to that inside the dynamo. Line-of-sight observations of polarized emission are synthesized to explore the feasibility of using the local reduction of Faraday depolarization to infer the sign of helicity of magnetic fields in the solar corona. This approach was previously identified as an observational diagnostic in the context of galactic magnetic fields. Based on our simulations, we show that this method can be successful in the solar context if sufficient statistics is gathered by using averages over ring segments in the corona separately for the regions north and south of the solar equator.Comment: 5 pages, 3 figures, published in ApJ

Near-Horizon Extremal Geometries: Coadjoint Orbits and Quantization

The NHEG algebra is an extension of Virasoro introduced in [arXiv:1503.07861]; it describes the symplectic symmetries of $(n+4)$-dimensional Near Horizon Extremal Geometries with $SL(2,R)\times U(1)^{n+1}$ isometry. In this work we construct the NHEG group and classify the (coadjoint) orbits of its action on phase space. As we show, the group consists of maps from an $n$-torus to the Virasoro group, so its orbits are bundles of standard Virasoro coadjoint orbits over $T^n$. We also describe the unitary representations that are expected to follow from the quantization of these orbits, and display their characters. Along the way we show that the NHEG algebra can be built from u(1) currents using a twisted Sugawara construction.Comment: 22 pages, one figure. v2: Title expanded, various minor clarifications added. Published in JHE

Gravitational Waves from Preheating in M-flation

Matrix inflation, or M-flation, is a string theory motivated inflationary model with three scalar field matrices and gauge fields in the adjoint representation of the $\mathbf{U}(N)$ gauge group. One of these $3N^2$ scalars appears as the effective inflaton while the rest of the fields (scalar and gauge fields) can play the role of isocurvature fields during inflation and preheat fields afterwards. There is a region in parameter space and initial field values, "the hilltop region," where predictions of the model are quite compatible with the recent Planck data. We show that in this hilltop region, if the inflaton ends up in the supersymmetric vacuum, the model can have an embedded preheating mechanism. Couplings of the preheat modes are related to the inflaton self-couplings and therefore are known from the CMB data. Through lattice simulations performed using a symplectic integrator, we numerically compute the power spectra of gravitational waves produced during the preheating stage following M-flation. The preliminary numerical simulation of the spectrum from multi-preheat fields peaks in the GHz band with an amplitude $\Omega_{\mathrm{gw}}h^{2} \propto 10^{-16}$, suggesting that the model has concrete predictions for the ultra-high frequency gravity-wave probes. This signature could be used to distinguish the model from rival inflationary modelsComment: v1:27 pages and 7 figures; v2: typos corrected; v3: references added; v4: matched the JCAP versio

A note on the M2-M5 brane system and fuzzy spheres

This note covers various aspects of recent attempts to describe membranes ending on fivebranes using fuzzy geometry. In particular, we examine the Basu-Harvey equation and its relation to the Nahm equation as well as the consequences of using a non-associative algebra for the fuzzy three-sphere. This produces the tantalising result that the fuzzy funnel solution corresponding to Q coincident membranes ending on a five-brane has $Q^{3/2}$ degrees of freedom.Comment: 17 pages, late

Aging of rotational diffusion in colloidal gels and glasses

We study the rotational diffusion of aging Laponite suspensions for a wide range of concentrations using depolarized dynamic light scattering. The measured orientational correlation functions undergo an ergodic to non-ergodic transition that is characterized by a concentration-dependent ergodicity-breaking time. We find that the relaxation times associated with rotational degree of freedom as a function of waiting time, when scaled with their ergodicity-breaking time, collapse on two distinct master curves. These master curves are similar to those previously found for the translational dynamics; The two different classes of behavior were attributed to colloidal gels and glasses. Therefore, the aging dynamics of rotational degree of freedom provides another signature of the distinct dynamical behavior of colloidal gels and glasses.Comment: 12 pages, 7 figure

Dynamic Monte Carlo Simulations of Anisotropic Colloids

We put forward a simple procedure for extracting dynamical information from Monte Carlo simulations, by appropriate matching of the short-time diffusion tensor with its infinite-dilution limit counterpart, which is supposed to be known. This approach --discarding hydrodynamics interactions-- first allows us to improve the efficiency of previous Dynamic Monte Carlo algorithms for spherical Brownian particles. In a second step, we address the case of anisotropic colloids with orientational degrees of freedom. As an illustration, we present a detailed study of the dynamics of thin platelets, with emphasis on long-time diffusion and orientational correlations.Comment: 12 pages, 9 figure

p-p' System with B-field, Branes at Angles and Noncommutative Geometry

We study the generic $p-p^\prime$ system in the presence of constant NS 2-form $B_{ij}$ field. We derive properties concerning with the noncommutativity of D-brane worldvolume, the Green functions and the spectrum of this system. In the zero slope limit, a large number of light states appear as the lowest excitations in appropriate cases. We are able to relate the energies of the lowest states after the GSO projection with the configurations of branes at angles. Through analytic continuation, the system is compared with the branes with relative motion.Comment: 21 pages, Latex. References regarding to section 3 and 4 added. Typos correcte

Five-brane Calibrations and Fuzzy Funnels

We present a generalisation of the Basu-Harvey equation that describes membranes ending on intersecting five-brane configurations corresponding to various calibrated geometries.Comment: 20 pages, latex, v2: typos fixed and refs adde

Non-Commutative GUTs, Standard Model and C,P,T properties from Seiberg-Witten map

Noncommutative generalizations of Yang-Mills theories using Seiberg-Witten map are in general not unique. We study these ambiguities and see that SO(10) GUT, at first order in the noncommutativity parameter \theta, is unique and therefore is a truly unified theory, while SU(5) is not. We then present the noncommutative Standard Model compatible with SO(10) GUT. We next study the reality, hermiticity and C,P,T properties of the Seiberg-Witten map and of these noncommutative actions at all orders in \theta. This allows to compare the Standard Model discussed in [5] with the present GUT inspired one.Comment: 9 pages. Presented at the Balkan Workshop 2003, Vrnjacka Banja, 29.8-2.9.2003 and at the 9th Adriatic Meeting, Dubrovnik, 4-14.9.200