Constraints on Braneworld Gravity Models from a Kinematic Limit on the Age of the Black Hole XTE J1118+480

In braneworld gravity models with a finite AdS curvature in the extra dimension, the AdS/CFT correspondence leads to a prediction for the lifetime of astrophysical black holes that is significantly smaller than the Hubble time, for asymptotic curvatures that are consistent with current experiments. Using the recent measurements of the position, three-dimensional spatial velocity, and mass of the black hole XTE J1118+480, I calculate a lower limit on its kinematic age of 11 Myr (95% confidence). This translates into an upper limit for the asymptotic AdS curvature in the extra dimensions of 0.08 mm, which significantly improves the limit obtained by table-top experiments of sub-mm gravity.Comment: 4 pages, to appear in the Physical Review Letter

Hybrid Thermal-Nonthermal Synchrotron Emission from Hot Accretion Flows

We investigate the effect of a hybrid electron population, consisting of both thermal and non-thermal particles, on the synchrotron spectrum, image size, and image shape of a hot accretion flow onto a supermassive black hole. We find two universal features in the emitted synchrotron spectrum: (i) a prominent shoulder at low (< 10^11 Hz) frequencies that is weakly dependent on the shape of the electron energy distribution, and (ii) an extended tail of emission at high (> 10^13 Hz) frequencies whose spectral slope depends on the slope of the power-law energy distribution of the electrons. In the low-frequency shoulder, the luminosity can be up to two orders of magnitude greater than with a purely thermal plasma even if only a small fraction (< 1%) of the steady-state electron energy is in the non-thermal electrons. We apply the hybrid model to the Galactic center source, Sgr A*. The observed radio and IR spectra imply that at most 1% of the steady-state electron energy is present in a power-law tail in this source. This corresponds to no more than 10% of the electron energy injected into the non-thermal electrons and hence 90% into the thermal electrons. We show that such a hybrid distribution can be sustained in the flow because thermalization via Coulomb collisions and synchrotron self-absorption are both inefficient. The presence of non-thermal electrons enlarges the size of the radio image at low frequencies and alters the frequency dependence of the brightness temperature. A purely thermal electron distributions produces a sharp-edged image while a hybrid distribution causes strong limb brightening. These effects can be seen up to frequencies ~10^11 Hz and are accessible to radio interferometers.Comment: 33 pages with figures, to appear in the Astrophysical Journa

An easy to calculate equation to estimate GFR based on inulin clearance

Background. For the estimation of renal function on the basis of serum creatinine, either the Cockcroft-Gault (CG) equation or the MDRD formula is commonly used. Compared to MDRD (using power functions), CG has the advantage of easy calculability at the bedside. MDRD, however, approaches glomerular filtration rate (GFR) more precisely than CG and gives values corrected for a body surface area (BSA) of 1.73 m2. We wondered whether CG could be adapted to estimate GFR rather than creatinine clearance without losing the advantage of easy calculability. In this prospective study, inulin clearance under well-defined conditions was taken as the gold standard for GFR. Methods. In 182 living kidney donors, inulin clearance was measured under standardized conditions (protein, salt and water intake, overnight stay) before and after nephrectomy. Together with the serum creatinine level, and demographic and clinical data, 281 measurements of inulin clearance were used to compare the accuracy of different estimation equations. Using stepwise multiple regression, a new set of constants was defined for a CG-like equation in order to estimate GFR. Results. The MDRD equation underestimated GFR by 9%, and the quadratic equation suggested by Rule overestimated GFR by 12.4%. The new CG-like equation, even when calculated with ‘mental arithmetic-friendly' rounded parameters, showed significantly less bias (1.2%). The adapted equation is Conclusions. We propose the CG-like equation called IB-eGFR (Inulinclearance Based eGFR) to estimate GFR more reliably than MDRD, Rule's equation or the original Cockcroft-Gault equation. As our data represent a Caucasian population, the adapted equation is still to be validated for patients of other ethnicit

Quantifying the Dynamics of Bacterial Secondary Metabolites by Spectral Multiphoton Microscopy

Phenazines, a group of fluorescent small molecules produced by the bacterium Pseudomonas aeruginosa, play a role in maintaining cellular redox homeostasis. Phenazines have been challenging to study in vivo due to their redox activity, presence both intra- and extracellularly, and their diverse chemical properties. Here, we describe a noninvasive in vivo optical technique to monitor phenazine concentrations within bacterial cells using time-lapsed spectral multiphoton fluorescence microscopy. This technique enables simultaneous monitoring of multiple weakly fluorescent molecules (phenazines, siderophores, NAD(P)H) expressed by bacteria in culture. This work provides the first in vivo measurements of reduced phenazine concentration as well as the first description of the temporal dynamics of the phenazine-NAD(P)H redox system in Pseudomonas aeruginosa, illuminating an unanticipated role for 1-hydroxyphenazine. Similar approaches could be used to study the abundance and redox dynamics of a wide range of small molecules within bacteria, both as single cells and in communities

SU(N) Gauge theories for large N

86 σ.Μία εισαγωγή στις θεωρίες βαθμίδας για μεγάλο Ν όπως αυτή διαμορφώθηκε από την εργασία του G. t' Hooft. Περιγραφή της διακριτοποίησης στο Lattice και εφαρμογή της ανάλυσης των θεωριών βαθμίδας για μεγάλο Ν στα πλαίσια του Lattice. Ανάφορά των σύγχρονων τεχνικών του θερμοδυναμικού μοντέλου, του μοντέλου Eguchi-Kawai, των φερμιονίων Wilson και των τεχνικών απομείωσης όγκου.This volume is a basic introduction to large N gauge theories and the parallel development of the Lattice formalization from Wilson and others. A particular attention to the technics that introduce results of large N to Lattice simulations. The modern techniques widely used in Lattice this days presented like the Eguchi-Kawai model, the volume reduction techniques, the twisted E-K, the factorization properties and the basic principles that lead to the Monte Carlo simulations of the Lattice.Δημήτριος Θ. Κούτα

Papillary Thyroid Carcinoma Intertwined with Hashimoto’s Thyroiditis: An Intriguing Correlation

Illustrating the ancient link connecting inflammation with cancer, the correlation of papillary thyroid carcinoma (PTC) with Hashimoto’s thyroiditis (HT) has long been pursued as intersection of autoimmunity-induced chronic inflammation and tumor-induced immunity. The dramatic rise of the incidence of PTC οver the last decades—the main culprit for “thyroid cancer (TC) epidemic”—parallels the increasing incidence of HT, potentially reflecting a pathogenetic link that could be harnessed in diagnostics and therapeutics. Prompted by this perspective, in the present chapter, we dissect the hitherto elusive interrelationship of PTC with HT, focusing on four issues: firstly, an unresolved conundrum is whether PTC emerges due to or notwithstanding immune response or mirrors the “tumor defense-induced autoimmunity.” Secondly, the interrelationship of HT with PTC may be merely epiphenomenon of selection bias inherent in thyroidectomy series. Thirdly, the impact of HT on coexistent PTC is equivocal—host protective versus tumor protective. Fourthly, translating serum concentrations of thyroid autoantibodies and thyroid-stimulating hormone (TSH) into predictive and prognostic PTC biomarkers dichotomizes, till now, the researchers. In the era of precision medicine, illuminating whether HT precipitates PTC or vice versa is awaited with anticipation in order to refine the preventive and therapeutic policy counteracting “TC epidemic.

Developing novel drugs for systemic lupus erythematosus. Lessons learned from the belimumab trials

Systemic lupus erythematosus is the prototypic autoimmune disease with a broad range of clinical manifestations and a complex pathogenesis. B-cells hold a central role in its pathogenesis, not only as autoantibody producing cells, but also by producing other inflammatory mediators and by presenting autoantigens to autoreactive T cells. BlyS, a soluble ligand of the TNF cytokine family, is a key factor affecting B-cell homeostasis and survival and its blockade ameliorated the disease in animal models and preclinical studies of SLE. Following an unsuccessful phase II trial of belimumab, a monoclonal antibody targeting BlyS, two large phase III studies in patients with mild-to-moderate disease, BLISS-52 and BLISS-76, met their primary endpoints showing better efficacy of the drug over standard of care alone. To this end, development of a novel more sensitive responder index and improvements in study designs were crucial. As a result, belimumab became the first drug to get approval for the treatment of SLE after more than 50 years. In this paper we discuss the rationale, development, indications, lessons learned, pitfalls and challenges for this novel therapy and point-out to additional issues that need to be addressed in the future.http://dx.doi.org/10.7175/rhc.v3i3.20