Implementation of binary stochastic STDP learning using chalcogenide-based memristive devices

The emergence of nano-scale memristive devices encouraged many different research areas to exploit their use in multiple applications. One of the proposed applications was to implement synaptic connections in bio-inspired neuromorphic systems. Large-scale neuromorphic hardware platforms are being developed with increasing number of neurons and synapses, having a critical bottleneck in the online learning capabilities. Spike-timing-dependent plasticity (STDP) is a widely used learning mechanism inspired by biology which updates the synaptic weight as a function of the temporal correlation between pre- and post-synaptic spikes. In this work, we demonstrate experimentally that binary stochastic STDP learning can be obtained from a memristor when the appropriate pulses are applied at both sides of the device

Factors involved in soil organic matter stabilization in Peruvian Amazonian soils (Ucayali region) and the molecular composition of extractable lipids

Poster E1012b presentado en el 27th International Meeting on Organic Geochemistry September 13–18, 2015, Prague, Czech RepublicAmazonian ecosystems are considered important sinks for atmospheric CO2 on Earth. It is therefore desirable to preserve their biodiversity and productivity. In this communication an assessment of the influence of different agro-forestry practices on soil C storage in representative ecosystems from the Peruvian Ucayali region is approached by analyzing the soil lipid fraction. In fact, this organic matter fraction is an important source of analytical surrogates of soil C stabilization and accumulation processes (Naafs at al., 2004; Poulenard et al., 2004; Rumpel et al., 2004). Top (0–20 cm) and subsoil (20–40 cm) samples were taken from the Amazonian Ucayali region (Pucallpa, Perú), ranging from recent alluvial soils in muddy zones of riverside areas (wetlands referred to as ‘mud’, ‘beach’ and low ‘restinga’ soils) to more developed soils located in medium and higher riverine terraces, as well as in hills. The lipid fraction was Soxhlet extracted with a mixture of ichloromethane:methanol (2:1 by vol.), saponified and divided into neutral and acid subfractions. The acid fractions were then sequentially methylated and silylated prior to the chromatographic analysis (González-Vila et al., 2003). Neutral and acid sub-fractions were separated and the major compounds were identified by gas chromatography-mass spectrometry using an HP G1800A GCD System (electron impact detector at 70 eV) equipped with a DB-5 fused silica capillary column (30 m × 0.32 mm i.d., film thickness 0.25 µm) and using He as carrier gas at a flow rate of 1.5 mL min-1. The chromatographic oven temperature was programmed to increase from 40 to 100 ºC at 30 ºC min-1 and then to 300 ºC at 6 ºC min -1. The values of soil organic matter and lipids ranged from 25.8 to 5.8 g kg-1, and from 5.2 to 0.2 g kg-1, respectively. This variability as well as the differences in lipid molecular composition could suggest differences in the soils’ use and management practices (Van Bergen et al.,1996). The main families of signature lipids detected in the soil extracts were n-alkanes, linear isoprenoids, cyclic alkanes, n-fatty acids, branched fatty acids, unsaturated fatty acids, hydroxyacids, n-alcohols, ketones, polycyclic hydrocarbons and sterols. Very significant differences in qualitative and quantitative lipid composition were found in terms of soil depth. This effect was more pronounced in the soils from the riverine high terraces devoted to agro-forestry practices (Figs. 1 and 2). In addition, lipidic compounds of high molecular weight (i.e., di- and triterpenes) were detected as regular components of the free lipid fractions from the different ecosystems (wetlands, terraces and hills) reflecting specific vegetation and soil-use influences. Xenobiotic compounds (naphthenic acids) detected within the unresolved chromatographic ‘hump’ (highly unresolved mixture of cyclic or branched hydrocarbons) were also observed, indicating anthropogenic contamination by mineral oils. Likewise, dialkyl phthalates (Phth) from plasticizers were also detected.Projects CGL2012-38655-C04-01 and CGL2008-04296 and fellowship BES-2013-062573 given to N.T.J.M by the Spanish Ministry of Economy and Competitiveness. Dr. J.M.R. is the recipient of a fellowship from the JAE-Doc subprogram financed by the CSIC and the European Social Fund.Peer Reviewe

Accretion, ejection and reprocessing in supermassive black holes

This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of active galactic nuclei. For a summary, we refer to the paper.Comment: White Paper in Support of the Mission Concept of the Large Observatory for X-ray Timin

Decreased peripheral health service utilisation during an outbreak of Marburg haemorrhagic fever, Uíge, Angola, 2005.

In 2005, a Marburg haemorrhagic fever (MHF) outbreak occurred in Uíge province, Angola, which had its epicentre in Uíge municipality. Concurrently, a health facility located a considerable distance from the outbreak's epicentre reported a drastic reduction in attendance, possibly due to a remote effect of the ongoing MHF outbreak. Health officials should devise strategies to ensure that communities far from a filovirus haemorrhagic fever epicentre are not adversely affected by interventions at the epicentre and, to the greatest extent possible, ensure that these peripheral communities receive essential medical care during an epidemic

Comunicación poliédrica: biopsia transformativa de la Biblioteca de Seattle

Photography is undoubtedly a fundamental tool in the narrative strategy of architecture, both in its creation as its “reproduction”. So much so, that allows us to create new different realities from a same object and gives rise to multiple interpretations. To understand how the communicative strategy has a strong impact on the perception of the architectural object, we turned to such a blunt, pregnant and iconic project as the Seattle Library of OMA. This building has appeared in countless different media related with architecture from such opposite perspectives that, in some cases, the project is unrecognizable. In this regard, we consider this case to be a paradigm of the polyform architectural communication. We will make a trip visiting different interpretations of this project basically depending on the perspective of photography to verify our hypothesis, after contextualizing the development of the project. We will start with the first OMA’s publication that reflected the project, which was “Content” (Ed. Taschen, 2004). Afterwards we will analyze the initial conceptual proposal submitted to the competition (OMA with LMN Architecture, Bruce Mau and Hans Werlemann), which turns out to be very revealing at a communicative level. Then we will study the development displayed in the web page of the local partners of OMA in Seattle, LMN Architects. Finally, to perform a full revision of the multiple communicative aspects of the project, we will seek the local press, whose code is intended to be for the general public. All those different approaches will lead us to conclude that the communication in architecture has necessary a strong influence in the message, both in its aspect and content, being an undisputed tool of projection and transformation.La fotografía es, indudablemente, una herramienta fundamental en la estrategia narrativa de la arquitectura, tanto en su creación como en su “reproducción”. Tanto es así, que permite originar nuevas realidades a partir de un mismo objeto reflejado y dar lugar a interpretaciones múltiples. Para llegar a comprender cómo la estrategia comunicativa incide en la percepción del objeto arquitectónico, recurrimos a un proyecto contundente, pregnante y con una carga objetual muy trascendente, como es la Biblioteca de Seattle, de OMA. Este proyecto ha sido reflejado en incontables medios relacionados con la arquitectura, desde perspectivas tan opuestas que, en determinadas visiones, el proyecto deja de ser reconocible. En este sentido, lo consideramos un paradigma de la comunicación arquitectónica poliédrica. Haremos un repaso por las interpretaciones más destacadas del proyecto en función de su diversidad, basándonos principalmente en la perspectiva fotográfica, de cara a verificar nuestra hipótesis. Comenzaremos por la primera publicación que reflejó este proyecto, que fue “Content” (Ed. Taschen, 2004). Después analizaremos la propuesta conceptual inicial que presentó OMA al concurso (junto a LMN Architecture, Bruce Mau y Hans Werlemann), que resulta especialmente reveladora a nivel de comunicación. Posteriormente estudiaremos la estrategia narrativa desarrollada por los socios locales de OMA en Seattle (el estudio LMN Architects) a través de su página web. Por último, para realizar un barrido completo por las múltiples facetas comunicativas del proyecto, acudimos a la reinterpretación que del mismo se hace en la prensa local, cuyo código va específicamente dirigido al público general. Todas estas aproximaciones tan diversas nos lleva a concluir que la comunicación en la arquitectura incide fuertemente en el mensaje, tanto en su forma como en su contenido, siendo una herramienta indiscutible de proyección y transformación

The history of star formation and mass assembly in early-type galaxies

We define a volume limited sample of over 14,000 early-type galaxies (ETGs) selected from data release six of the Sloan Digital Sky Survey. The density of environment of each galaxy is robustly measured. By comparing narrow band spectral line indices with recent models of simple stellar populations (SSPs) we investigate trends in the star formation history as a function of galaxy mass (velocity dispersion), density of environment and galactic radius. We find that age, metallicity and alpha-enhancement all increase with galaxy mass and that field ETGs are younger than their cluster counterparts by ~2 Gyr. We find negative radial metallicity gradients for all masses and environments, and positive radial age gradients for ETGs with velocity dispersion over 180 km/s. Our results are qualitatively consistent with a relatively simple picture for ETG evolution in which the low-mass halos accreted by a proto-ETG contained not only gas but also a stellar population. This fossil population is preferentially found at large radii in massive ETGs because the stellar accretions were dissipationless. We estimate that the typical, massive ETG should have been assembled at z < 3.5. The process is similar in the cluster and the field but occurred earlier in dense environments.Comment: 5 pages, 2 figures. Submitted to MNRA

BIOF\u2013HILO assay: A new MALDI\u2013TOF mass spectrometry based method for discriminating between high-and low-biofilm-producing candida parapsilosis isolates

Candida parapsilosis is the most frequent cause of catheter-related candidemia among non-Candida albicans species. This may be related to intrinsic capabilities as adhering and forming a biofilm on abiotic surfaces such as on medical devices. As previously demonstrated, patients infected with high biofilm-producing C. parapsilosis isolates had a greater mortality risk compared to patients infected with low biofilm-producing C. parapsilosis isolates. We developed the BIOF\u2013HILO assay, a MALDI\u2013TOF mass spectrometry (MS)-based assay, which compares mass spectra obtained from attached and suspended isolate cells during the early (i.e., 3-h) adhesion phase of in vitro biofilm formation. The composite correlation index (CCI) analysis was used to discriminate between mass spectra differences of the two cell types, classifying all 50 C. parapsilosis clinical isolates, included in the study, after only 3-h of testing, in high or low biofilm producers. All high (n = 25) or low (n = 25) biofilm producers had, according to CCI mass spectra comparison values, higher or lower than one CCI ratios, which were obtained by dividing the CCIsuspendedcells by the CCIattachedcells . In conclusion, the BIOF\u2013HILO assay allows a rapid categorization of C. parapsilosis clinical isolates in high or low biofilm producers. This information, if timely provided to physicians, may improve treatment outcomes in patients with C. parapsilosis candidemia

Prediction equations of skinfold in children of primary school

El objetivo de este trabajo es crear ecuaciones que estimen las medidas de los pliegues cutáneos para escolares de 6 a 13 años de edad. Como resultado se obtuvieron catorce ecuaciones que estiman algunos pliegues cutáneos. Las ecuaciones se validaron con muestras aleatorias de 479 niñas y 541 niños del estado de Puebla y otras 2 muestras aleatorias del estado de Veracruz con 155 niñas y 146 niños respectivamente; las mediciones directas se realizaron con la metodología y unidades ISAK (International Society for the Advancement of Kinanthropometry)The aim of this paper is to create equations that predict the skinfold measures for school children 6 to 13 years old. Fourteen resulting equations were derived to estimate some measures of skinfold. The equations were validated with random samples of 479 girls and 541 boys in the state of Puebla and 2 other random samples of the state of Veracruz with 155 girls and 146 boys respectively; direct measurements were performed with the methodology and units ISAK (International Society for the Advancement of Kinanthropometr