Modeling the skin pattern of fishes

Complicated patterns showing various spatial scales have been obtained in the past by coupling Turing systems in such a way that the scales of the independent systems resonate. This produces superimposed patterns with different length scales. Here we propose a model consisting of two identical reaction-diffusion systems coupled together in such a way that one of them produces a simple Turing pattern of spots or stripes, and the other traveling wave fronts that eventually become stationary. The basic idea is to assume that one of the systems becomes fixed after some time and serves as a source of morphogens for the other system. This mechanism produces patterns very similar to the pigmentation patterns observed in different species of stingrays and other fishes. The biological mechanisms that support the realization of this model are discussed

Using the Sound Card as a Timer

Experiments in mechanics can often be timed by the sounds they produce. In such cases, digital audio recordings provide a simple way of measuring time intervals with an accuracy comparable to that of photogate timers. We illustrate this with an experiment in the physics of sports: to measure the speed of a hard-kicked soccer ball.Comment: 3 pages, 4 figures, Late

Pulsar Prospects for the Cherenkov Telescope Array

In the last few years, the Fermi-LAT telescope has discovered over a 100 pulsars at energies above 100 MeV, increasing the number of known gamma-ray pulsars by an order of magnitude. In parallel, imaging Cherenkov telescopes, such as MAGIC and VERITAS, have detected for the first time VHE pulsed gamma-rays from the Crab pulsar. Such detections have revealed that the Crab VHE spectrum follows a power-law up to at least 400 GeV, challenging most theoretical models, and opening wide possibilities of detecting more pulsars from the ground with the future Cherenkov Telescope Array (CTA). In this contribution, we study the capabilities of CTA for detecting Fermi pulsars. For this, we extrapolate their spectra with "Crab-like" power-law tails in the VHE range, as suggested by the latest MAGIC and VERITAS results.Comment: 4 pages, 3 figures. In Proceedings of the 2012 Heidelberg Symposium on High Energy Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184

Rangeland Degradation in Mongolia – Using State and Transition Models to Help Understand Rangeland Dynamics

Rangeland degradation and soil erosion pose constant challenges to the management of natural resources in Mongolia. Large increases in livestock numbers since the early 1990s, together with increasing temperatures and higher frequency of extreme weather events have led to widespread degradation of rangeland resources, to the extent that today, nearly 57% of rangelands in Mongolia are considered degraded to some degree. New ways of understanding the dynamics of rangeland ecosystems and guidelines to conserve healthy and productive rangelands are urgently needed. The application of State and Transition Models (STMs) in ecosystem management has shown promise to understand the mechanistic processes behind rangeland degradation and to suggest appropriate interventions for maintaining the health or restoring degraded rangelands. The Green Gold-Animal Health project funded by the Swiss Development Agency in Mongolia was the first initiative aimed at developing and applying STMs to Mongolian rangeland management. Here we describe the development of STMs for the most common rangeland types in Mongolia, including the definition of reference and alternative rangeland states and “recovery classes”, based on the timelines and management actions needed to recover a reference state. Our results show that STMs are effective tools for analysing and interpreting rangeland health monitoring data and provide a scientific basis for planning and implementing resilience-based rangeland management. Furthermore, STMs facilitate synthesis of available knowledge and help identify areas where more information is needed. In summary, STMs have the potential to serve as a valuable tool for better communication of rangeland health assessments and decision making to facilitate appropriate management

Systematic search for gamma-ray periodicity in active galactic nuclei detected by the Fermi Large Area Telescope

We use nine years of gamma-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves of more than two thousand active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different techniques are used, which are organized in an automatic periodicity-search pipeline, in order to search for evidence of periodic emission in gamma rays. Understanding the processes behind this puzzling phenomenon will provide a better view about the astrophysical nature of these extragalactic sources. However, the observation of temporal patterns in gamma-ray light curves of AGN is still challenging. Despite the fact that there have been efforts on characterizing the temporal emission of some individual sources, a systematic search for periodicities by means of a full likelihood analysis applied to large samples of sources was missing. Our analysis finds 11 AGN, of which 9 are identified for the first time, showing periodicity at more than 4sigma in at least four algorithms. These findings will help in solving questions related to the astrophysical origin of this periodic behavior.Comment: 16 pages, 5 figures, 4 tables. Accepted by Ap

Anomalías congénitas de la columna vertebral: el caso de Fuentenegroso

X Congreso Nacional de Paleopatología. Univesidad Autónoma de Madrid, septiembre de 200

Multinet : enabler for next generation enterprise wireless services

Wireless communications are currently experiencing a fast migration toward the beyond third-generation (B3G)/fourth generation (4G) era. This represents a generational change in wireless systems: new capabilities related to mobility and new services support is required and new concepts as individual-centric, user-centric or ambient-aware communications are included. One of the main restrictions associated to wireless technology is mobility management, this feature was not considered in the design phase; for this reason, a complete solution is not already found, although different solutions are proposed and are being proposed. In MULTINET project, features as mobility and multihoming are applied to wireless network to provide the necessary network and application functionality enhancements for seamless data communication mobility considering end-user scenario and preferences. The aim of this paper is to show the benefits of these functionalities from the Service Providers and final User point of view

Synthesis of a new vanadyl(IV) complex with trehalose (TreVO): insulin-mimetic activities in osteoblast-like cells in culture

Vanadium compounds show interesting biological and pharmacological properties. Some of them display insulin-mimetic effects and others produce antitumor actions. The bioactivity of vanadium is present in inorganic species like the vanadyl(IV) cation or vanadate( V) anion. Nevertheless, the development of new vanadium derivatives with organic ligands which improve the beneficial actions and decrease the toxic effects is of great interest. On the other hand, the mechanisms involved in vanadium bioactivity are still poorly understood. A new vanadium complex of the vanadyl(IV) cation with the disaccharide trehalose (TreVO), Na6 [VO(Tre)2].4H2O, here reported, shows interesting insulin- mimetic properties in two osteoblast cell lines, a normal one (MC3T3E1) and a tumoral one (UMR106). The complex affected the proliferation of both cell lines in a different manner. On tumoral cells, TreVO caused a weak stimulation of growth at 5 lM but it inhibited cell proliferation in a dose-response manner between 50 and 100 lM. TreVO significantly inhibited UMR106 differentiation (15–25% of basal) in the range 5–100 lM. On normal osteoblasts, TreVO behaved as a mitogen at 5–25 lM. Different inhibitors of the MAPK pathway blocked this effect. At higher concentrations (75–100 lM), the complex was a weak inhibitor of the MC3T3E1 proliferation. Besides, TreVO enhanced glucose consumption by a mechanism independent of the PI3-kinase activation. In both cell lines, TreVO stimulated the ERK phosphorylation in a dose- and time-dependent manner. Different inhibitors (PD98059, wortmannin, vitamins C and E) partially decreased this effect, which was totally inhibited by their combination. These results suggest that TreVO could be a potential candidate for therapeutic treatments

Deducing high pressure behavior for chemically fragile systems: the polymorphism of spironolactone

International audienc

Socio-Economic Status, Territory and Political Participation in Twenty-First-Century Mexico

This article is built on the reflections that the authors have had during their latest research on political participation in several municipalities of Mexico. Thus, based on the ethnographies conducted between 2006 and 2016, mainly in the town of Xico (Veracruz state), we set up as analyzing unities specific political interactions (including patronizing) among Mexican citizens within the five types recognized by Social Sciences: voting, campaigning, contacting political officials, working on public affairs and talking about politics. On this basis, we explore the articulation of the aforementioned interactions and, more specifically, of the roles adopted by the interacting citizens as identity markers linking these people in a highlighted way with a series of socio?economic and socio?territorial features, dimensions that, ultimately, turn out inseparable from the existing power relations in the local societies. In conclusion, we are of the opinion that, together with indicators of income, education, professional category or living nearby territory, it can be affirmed that the political behavior in Mexico is shown as both socio?economic indicator and socio?territorial belonging not because parties represent interests of class, but because there are well defined spheres of political behavior depending on the socio?economic stratum and the socio?territorial belonging of the individual