Current Understanding of the Neural Stem Cell Niches.

Neural stem cells (NSCs) are self-renewing, multipotent cells which give rise to all components of the central nervous system (CNS) during embryogenesis, but also activate in response to injury and disease and maintain a certain level of neurogenic activity throughout adulthood. This activity takes place in specialized regions of the brain, the neurovascular niches, whose main role is to control the behaviour of the CNS. In adult mammals, two main "canonical" niches have been described: The subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) of the dentate gyrus. This review discusses our current understanding of the neural stem cells and their canonical niches, as well as their structure, behaviours, and role in neural disease.

A network formation game for the emergence of hierarchies.

We propose a novel network formation game that explains the emergence of various hierarchical structures in groups where self-interested or utility-maximizing individuals decide to establish or severe relationships of authority or collaboration among themselves. We consider two settings: we first consider individuals who do not seek the other party's consent when establishing a relationship and then individuals who do. For both settings, we formally relate the emerged hierarchical structures with the novel inclusion of well-motivated hierarchy promoting terms in the individuals' utility functions. We first analyze the game via a static analysis and characterize all the hierarchical structures that can be formed as its solutions. We then consider the game played dynamically under stochastic interactions among individuals implementing better-response dynamics and analyze the nature of the converged networks.

Hydrodynamic evolution of plasma waveguides for soft-x-ray amplifiers.

High-density, collisionally pumped plasma-based soft-x-ray lasers have recently delivered hundreds of femtosecond pulses, breaking the longstanding barrier of one picosecond. To pump these amplifiers an intense infrared pulse must propagate focused throughout all the length of the amplifier, which spans several Rayleigh lengths. However, strong nonlinear effects hinder the propagation of the laser beam. The use of a plasma waveguide allows us to overcome these drawbacks provided the hydrodynamic processes that dominate the creation and posterior evolution of the waveguide are controlled and optimized. In this paper we present experimental measurements of the radial density profile and transmittance of such waveguide, and we compare them with numerical calculations using hydrodynamic and particle-in-cell codes. Controlling the properties (electron density value and radial gradient) of the waveguide with the help of numerical codes promises the delivery of ultrashort (tens of femtoseconds), coherent soft-x-ray pulses.

Automatic pneumonia detection based on ultrasound video analysis.

Pneumonia is a disease which causes high mortality in children under five years old, particularly in developing countries. This paper proposes a novel application of ultrasound video analysis for the detection of pneumonia. This application is based on the processing of small video chunks, in which an image processing algorithm analyzes each frame to get some overall video statistics. Then, based on these quantities, the likeness of presence of pneumonia in the video is determined. The algorithm exploits different geometrical properties of typical anatomical and pathological features that commonly appear in lung sonography and which are already clinically typified in the literature. Our technique has been tested on different transverse thoracic scanning protocols and probe's maneuvers, thus, under a variety of clinical and usage protocols. Then, it can be targeted towards screening applications. We present encouraging results (AUC measure between 0.7851 and 0.9177) based on the analysis of 346 videos with an average duration of eight seconds. The analyzed videos were taken from children who were between three and five years old. Finally, our algorithm can be used directly as a classifier, but we detail how its performance may be enhanced if used as a first stage of a larger pipeline of other complementary pneumonia detection processes.

Hydrodynamic study of plasma amplifiers for soft-x-ray lasers: a transition in hydrodynamic behavior for plasma columns with widths ranging from 20 µm to 2 mm.

Plasma-based seeded soft-x-ray lasers have the potential to generate high energy and highly coherent short pulse beams. Due to their high density, plasmas created by the interaction of an intense laser with a solid target should store the highest amount of energy density among all plasma amplifiers. Our previous numerical work with a two-dimensional (2D) adaptive mesh refinement hydrodynamic code demonstrated that careful tailoring of plasma shapes leads to a dramatic enhancement of both soft-x-ray laser output energy and pumping efficiency. Benchmarking of our 2D hydrodynamic code in previous experiments demonstrated a high level of confidence, allowing us to perform a full study with the aim of the way for 10-100 µJ seeded soft-x-ray lasers. In this paper, we describe in detail the mechanisms that drive the hydrodynamics of plasma columns. We observed transitions between narrow plasmas, where very strong bidimensional flow prevents them from storing energy, to large plasmas that store a high amount of energy. Millimeter-sized plasmas are outstanding amplifiers, but they have the limitation of transverse lasing. In this paper, we provide a preliminary solution to this problem.

Tumor pardo fronto-ethmoidal e hiperparatiroidismo secundario: presentación de caso / Fronto-ethmoidal brown tumor: case report

Los tumores pardos son lesiones óseas focales secundarias a hiperparatiroidismo. Se han descrito en la literatura 7 casos asociados a hiperparatiroidismo secundario localizados en hueso frontal, maxilar y etmoidal que involucran la órbita. Se presenta un caso clínico, en una mujer de 58 años de edad con insuficiencia crónica de 18 años de evolución; en diálisis peritoneal crónica ambulatoria y en programa de transplante renal. Seis meses antes inicia aumento de volumen inter ciliar de predominio izquierdo. presenta desplazamiento ocular izquierdo por tumor de aproximadamente 10 x 7 cm, fijo, no doloroso y sin cambios tróficos en la piel supra yacente. Se extirpó el tumor que fue diagnosticado como "tumor pardo"