Scalar Emission in the Bulk in a Rotating Black Hole Background

We study the emission of scalars into the bulk from a higher-dimensional rotating black hole. We obtain an analytic solution to the field equation by employing matching techniques on expressions valid in the near-horizon and far-field regimes. Both analytic and numerical results for the absorption probability, in the low-energy and low-angular momentum limit, are derived and found to be in excellent agreement. We also compute the energy emission rate, and show that the brane-to-bulk ratio of the energy emission rates for scalar fields remains always larger than unity in the aforementioned regime.Comment: 14 pages, Latex file, 5 figures, references adde

Microbes Against Humanity, a workshop game for horrible students: using a creative card game in higher education microbiology teaching

Introducing creative workshops in higher education curricula, in addition to formal lectures, is an excellent way of reinforcing knowledge and encouraging creative thinking. In particular, the use of card games as a tool for inducing student engagement and enthusiasm has been reported to be a very effective approach. Here, we report an innovative card game-based workshop for use at the intermediate undergraduate level. The name of the game is Microbes Against Humanity and has been adapted from the widely known party game Cards Against Humanity, which is freely available under a creative commons licence. Overall, 64 students and two academics participated in this 2 h workshop. Our students found the workshop to be very enjoyable, considered it to be helpful for their learning and suggested interesting ideas for further improvement. In conclusion, it was shown that such exciting workshops can trigger students’ enthusiasm for microbiology and enhance their learning potential

On the Integrability of the Bukhvostov-Lipatov Model

The integrability of the Bukhvostov-Lipatov four-fermion model is investigated. It is shown that the classical model possesses a current of Lorentz spin 3, conserved both in the bulk and on the half-line for specific types of boundary actions. It is then established that the conservation law is spoiled at the quantum level -- a fact that might indicate that the quantum Bukhvostov-Lipatov model is not integrable, contrary to what was previously believed.Comment: 11 pages, 1 figure, LaTeX2e, AMS; new references adde

On the third level descendent fields in the Bullough-Dodd model and its reductions

Exact vacuum expectation values of the third level descendent fields $$ in the Bullough-Dodd model are proposed. By performing quantum group restrictions, we obtain $<L_{-3}{\bar L}_{-3}{\Phi}_{lk}>$ in perturbed minimal conformal field theories.Comment: 7 pages, LaTeX file with amssymb; to appear in Phys. Lett.

Greybody Factors for Brane Scalar Fields in a Rotating Black-Hole Background

We study the evaporation of (4+n)-dimensional rotating black holes into scalar degrees of freedom on the brane. We calculate the corresponding absorption probabilities and cross-sections obtaining analytic solutions in the low-energy regime, and compare the derived analytic expressions to numerical results, with very good agreement. We then consider the high-energy regime, construct an analytic high-energy solution to the scalar-field equation by employing a new method, and calculate the absorption probability and cross-section for this energy regime, finding again a very good agreement with the exact numerical results. We also determine the high-energy asymptotic value of the total cross-section, and compare it to the analytic results derived from the application of the geometrical optics limit.Comment: Latex file, 30 pages, 5 figures, typos corrected, version published in Phys. Rev.

Comparative evaluation of image reconstruction methods for the siemens PET-MR scanner using the stir library

With the introduction of Positron Emission Tomography - Magnetic Resonance (PET-MR) scanners the development of new algorithms and the comparison of the performance of different iterative reconstruction algorithms and the characteristics of the reconstructed images data is relevant. In this work, we perform a quantitative assessment of the currently used ordered subset (OS) algorithms for low-counts PET-MR data taken from a Siemens Biograph mMR scanner using the Software for Tomographic Image Reconstruction (STIR, stir.sf.net). A comparison has been performed in terms of bias and coefficient of variation (CoV). Within the STIR library different algorithms are available, such as Order Subsets Expectation Maximization (OSEM), OS Maximum A Posteriori One Step Late (OSMAPOSL) with Quadratic Prior (QP) and with Median Root Prior (MRP), OS Separable Paraboloidal Surrogate (OSSPS) with QP and Filtered Back-Projection (FBP). In addition, List Mode (LM) reconstruction is available. Corrections for attenuation, scatter and random events are performed using STIR instead of using the scanner. Data from the Hoffman brain phantom are acquired, processed and reconstructed. Clinical data from the thorax of a patient have also been reconstructed with the same algorithms. The number of subsets does not appreciably affect the bias nor the coefficient of variation (CoV=11%) at a fixed sub-iteration number. The percentage relative bias and CoV maximum values for OSMAPOSL-MRP are 10% and 15% at 360 s acquisition and 12% and 15% for the 36 s, whilst for OSMAPOSL-QP they are 6% and 16% for 360 s acquisition and 11% and 23% at 36 s and for OSEM 6% and 11% for the 360 s acquisition and 10% and 15% for the 36 s. Our findings demonstrate that when it comes to low-counts, noise and bias become significant. The methodology for reconstructing Siemens mMR data with STIR is included in the CCP-PET-MR website

A non-standard matter distribution in the RS1 model and the coupling constant of the radion

In the zero mode approximation we solve exactly the equations of motion for linearized gravity in the Randall-Sundrum model with a non-standard distribution of matter in the neighbourhood of the negative tension brane. It is shown that the form of this distribution can strongly affect the coupling of the radion to matter. We believe that such a situation can arise in models with a realistic mechanisms of matter localization.Comment: 12 pages, LaTe

Greybody factors in a rotating black-hole background-II : fermions and gauge bosons

We study the emission of fermion and gauge boson degrees of freedom on the brane by a rotating higher-dimensional black hole. Using matching techniques, for the near-horizon and far-field regime solutions, we solve analytically the corresponding field equations of motion. From this, we derive analytical results for the absorption probabilities and Hawking radiation emission rates, in the low-energy and low-rotation case, for both species of fields. We produce plots of these, comparing them to existing exact numerical results with very good agreement. We also study the total absorption cross-section and demonstrate that, as in the non-rotating case, it has a different behaviour for fermions and gauge bosons in the low-energy limit, while it follows a universal behaviour -- reaching a constant, spin-independent, asymptotic value -- in the high-energy regime.Comment: 22 pages, 8 figures, added reference

Measuring the performance of prediction models to personalize treatment choice.

When data are available from individual patients receiving either a treatment or a control intervention in a randomized trial, various statistical and machine learning methods can be used to develop models for predicting future outcomes under the two conditions, and thus to predict treatment effect at the patient level. These predictions can subsequently guide personalized treatment choices. Although several methods for validating prediction models are available, little attention has been given to measuring the performance of predictions of personalized treatment effect. In this article, we propose a range of measures that can be used to this end. We start by defining two dimensions of model accuracy for treatment effects, for a single outcome: discrimination for benefit and calibration for benefit. We then amalgamate these two dimensions into an additional concept, decision accuracy, which quantifies the model's ability to identify patients for whom the benefit from treatment exceeds a given threshold. Subsequently, we propose a series of performance measures related to these dimensions and discuss estimating procedures, focusing on randomized data. Our methods are applicable for continuous or binary outcomes, for any type of prediction model, as long as it uses baseline covariates to predict outcomes under treatment and control. We illustrate all methods using two simulated datasets and a real dataset from a trial in depression. We implement all methods in the R package predieval. Results suggest that the proposed measures can be useful in evaluating and comparing the performance of competing models in predicting individualized treatment effect