Schwarzschild Black Branes and Strings in higher-dimensional Brane Worlds

We consider branes embedded in spacetimes of codimension 1 and 2, with a warped metric tensor for the subspace parallel to the brane. We study a variety of brane-world solutions arising by introducing a Schwarzschild-like black hole metric on the brane and we investigate the properties of the corresponding higher-dimensional spacetime. We demonstrate that normalizable bulk modes lead to a vanishing flow of energy through the naked singularities. From this point of view, these singularities are harmless. (28 refs)

Cosmological 3-Brane Solutions

We analyze cosmological equations in the brane world scenario with one extra space-like dimension. We demonstrate that the cosmological equations can be reduced to the usual 4D Friedmann type if the bulk energy-momentum tensor is different from zero. We then generalize these equations to the case of a brane of finite thickness. We also demonstrate that when the bulk energy-momentum tensor is different from zero, the extra space-like dimension can be compactified with a single brane and show that the stability of the radius of compactification implies standard cosmology and vice versa. For a brane of finite thickness, we provide a solution such that the 4D Planck scale is related to the fundamental scale by the thickness of the brane. In this case, compactification of the extra dimension is unnecessary.Comment: 14 pages, Latex file, no figures, typos corrected, comments and references added, version to appear in Physics Letters

Multiple outcome meta-analysis of gene-expression data in inflammatory bowel disease

We performed a multivariate meta-analysis of microarray data in Crohn's disease (CD) and Ulcerative colitis (UC), which are the main forms of inflammatory bowel disease (IBD). They share similar symptoms but differ in the location and extent of inflammation and in complications. We identified 249 differentially expressed genes (DEGs) in CD and 38 in UC at a false discovery rate of 1%. 20 of the DEGs were common to both diseases. A multivariate test identified 260 DEGs associated with IBD, 53 of which were not found in any of the disorders. We identified important molecular pathways implicated in the pathogenesis of IBD, such as the JAK/STAT and interferon-gamma signaling pathways, genes involved in cell adhesion, apoptosis and carcinogenesis. Among others, BCAT1 and GZMB are interesting novel DEGs that deserve further investigation in experimental models. The method could also be useful to other cases of meta-analysis of gene expression data

YAHTZEE game

75 σ.Στις σελίδες που ακολουθούν παρουσιάζεται το παιχνίδι Yahtzee, ένα παιχνίδι ζαριών με κανόνες πόκερ.Οι κανόνες Yahtzee δίνονται.Το παιχνίδι υποστηρίζει διάφορα ηχητικά εφέ και ένας εγγεγραμμένος παίκτης έχει τη δυνατότητα να αποθηκεύει το μεγαλύτερό του σκόρ.Το παιχνίδι έχει δημιουργηθεί ως μια web και desktop εφαρμογή.Επίσης, έχει σχεδιασθεί ως εφαρμογή ανεξαρτήτου πλατφόρμας για iOS, Symbian, Android, webOS, BlackBerry συσκευές.Στο τελευταίο κεφάλαιο, δίνονται τεχνικές σημειώσεις για την κατασκευή του παιχνιδιού.In the following pages, the game of Yahtzee is presented which is a dice game with poker rules.The Yahtzee rules are given.The Yahtzee game supports different sound effects and a registered player has the possibility to save his highscore.The game has been developed as a web and desktop application.Also, it has been built as a cross-platform application for iOS, Symbian, Android, webOS, BlackBerry devices.In the last chapter, technical notes about the development of Yahtzee are presented.Παναγιώτα Ι. Μπούτρο

Monetary policy and herd behavior: international evidence

This paper is motivated by the recent discussion on the need of market supervisors, regulators, and policy makers, to take into account the behavioral elements of market participant attitudes and psychological and cognitive biases when taking policy decisions. We contribute to the discussion by studying, for the first time, the relationship between conventional and unconventional central bank monetary policy and herd behavior in equity markets, and argue that the transmission channel, through which monetary policy may affect herd behavior, is economic expectations and investor sentiment. We combine a range of research methodologies to measure monetary policy, herd behavior, and their possible relation, and our results indicate that conventional and unconventional Fed monetary policy explains a significant percentage of US equity market herd behavior variance, while ECB monetary policy explains a lower percentage of Eurozone herding variance. Impulse Response Functions indicate that Fed’s conventional expansionary policy and non-standard policy reduces the levels of herding in the US equity market, while conventional ECB expansionary policy induces higher levels of herding in Spain and Italy. We also detect spill-over effects from Fed monetary policy to EU market herd behavior

Cortical Microcircuit Dynamics Mediating Binocular Rivalry: The Role of Adaptation in Inhibition

Perceptual bistability arises when two conflicting interpretations of an ambiguous stimulus or images in binocular rivalry (BR) compete for perceptual dominance. From a computational point of view, competition models based on cross-inhibition and adaptation have shown that noise is a crucial force for rivalry, and operates in balance with adaptation. In particular, noise-driven transitions and adaptation-driven oscillations define two dynamical regimes and the system explains the observed alternations in perception when it operates near their boundary. In order to gain insights into the microcircuit dynamics mediating spontaneous perceptual alternations, we used a reduced recurrent attractor-based biophysically realistic spiking network, well known for working memory, attention, and decision making, where a spike-frequency adaptation mechanism is implemented to account for perceptual bistability. We thus derived a consistently reduced four-variable population rate model using mean-field techniques, and we tested it on BR data collected from human subjects. Our model accounts for experimental data parameters such as mean time dominance, coefficient of variation, and gamma distribution fit. In addition, we show that our model operates near the bifurcation that separates the noise-driven transitions regime from the adaptation-driven oscillations regime, and agrees with Levelt’s second revised and fourth propositions. These results demonstrate for the first time that a consistent reduction of a biophysically realistic spiking network of leaky integrate-and-fire neurons with spike-frequency adaptation could account for BR. Moreover, we demonstrate that BR can be explained only through the dynamics of competing neuronal pools, without taking into account the adaptation of inhibitory interneurons. However, the adaptation of interneurons affects the optimal parametric space of the system by decreasing the overall adaptation necessary for the bifurcation to occur, and introduces oscillations in the spontaneous state

Single-Brane Cosmological Solutions with a Stable Compact Extra Dimension

We consider 5-dimensional cosmological solutions of a single brane. The correct cosmology on the brane, i.e., governed by the standard 4-dimensional Friedmann equation, and stable compactification of the extra dimension is guaranteed by the existence of a non-vanishing \hat{T}^5_5 which is proportional to the 4-dimensional trace of the energy-momentum tensor. We show that this component of the energy-momentum tensor arises from the backreaction of the dilaton coupling to the brane. The same positive features are exhibited in solutions found in the presence of non-vanishing cosmological constants both on the brane (\Lambda_{br}) and in the bulk (\Lambda_B). Moreover, the restoration of the Friedmann equation, with the correct sign, takes place for both signs of $\Lambda_B$ so long as the sign of $\Lambda_{br}$ is opposite $\Lambda_B$ in order to cancel the energy densities of the two cosmological constants. We further extend our single-brane thin-wall solution to allow a brane with finite thickness.Comment: 25 pages, Latex file, no figures, comments added, references updated, final version to appear in Physical Review

EVALUATION OF THE ALAMARBLUE ASSAY FOR ADHERENT CELL IRRADIATION EXPERIMENTS

The AlamarBlue assay is based on fluorometric detection of metabolic mitochondrial activity of cells. In this study, we determined the methodology for application of the assay to radiation response experiments in 96-well plates. AlamarBlue was added and its reduction measured 7 hours later. Selection of the initial number of plated cells was important so that the number of proliferating cells remains lower than the critical number that produced full AlamarBlue reduction (plateau phase) at the time points of measurements. Culture medium was replaced twice a week to avoid suppression of viability due to nutrient competition and metabolic waste accumulation. There was no need to replace culture medium before adding AlamarBlue. Cell proliferation continued after irradiation and the suppression effect on cell viability was most evident on day 8. At this time point, by comparing measurements from irradiated vs. non-irradiated cells, for various dose levels, a viability dose response curve was plotted. Immediately after the 8th day (nadir), cells started to re-grow at a rate inversely related to the radiation dose. By comparing measurements at the time point of nadir vs. a convenient subsequent time point, re-growth dose response abilities were plotted, simulating clonogenic assays