98 research outputs found
A Model of Graceful Exit in String Cosmology
We construct, for the first time, a model of graceful exit transition from a
dilaton-driven inflationary phase to a decelerated Friedman-Robertson-Walker
era. Exploiting a demonstration that classical corrections can stabilize a high
curvature string phase while the evolution is still in the weakly coupled
regime, we show that if additional terms of the type that may result from
quantum corrections to the string effective action exist, and induce violation
of the null energy condition, then evolution towards a decelerated
Friedman-Robertson-Walker phase is possible. We also observe that stabilizing
the dilaton at a fixed value, either by capture in a potential minimum or by
radiation production, may require that these quantum corrections are turned
off, perhaps by non-perturbative effects or higher order contributions which
overturn the null energy condition violation.Comment: 17 pages including 9 figures, RevTeX. Uses epsfi
High Proton Conductivity in a Flexible, Cross-Linked, Ultramicroporous Magnesium Tetraphosphonate Hybrid Framework
Multifunctional materials, especially those combining two or more properties of interest, are attracting immense attention due to their potential applications. MOFs, metal organic frameworks, can be regarded as multifunctional materials if they show another useful property in addition to the adsorption behavior. Here, we report a new multifunctional light hybrid, MgH6ODTMP·2H2O(DMF)0.5 (1), which has been synthesized using the tetraphosphonic acid H8ODTMP, octamethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid), by highthroughput methodology. Its crystal structure, solved by Patterson-function direct methods from synchrotron powder Xray diffraction, was characterized by a 3D pillared open
framework containing cross-linked 1D channels filled with water and DMF. Upon H2O and DMF removal and subsequent rehydration, MgH6ODTMP·2H2O (2) and MgH6ODTMP·6H2O (3) can be formed. These processes take place through crystalline−quasi-amorphous−crystalline transformations, during which the integrity of the framework is maintained. A water adsorption study, at constant temperature, showed that this magnesium tetraphosphonate hybrid reversibly equilibrates its lattice water content as a function of the water partial pressure. Combination of the structural study and gas adsorption characterization (N2, CO2, and CH4) indicates an ultramicroporous framework. High-pressure CO2 adsorption data are also reported. Finally, impedance data indicates that 3 has high proton conductivity σ = 1.6 × 10−3 S cm−1 at T = 292 K at ∼100% relative humidity with an activation energy of 0.31 eV.Proyecto nacional MAT2010-15175 (MICINN, España
Effectiveness of new tools to define an up-to-date patient safety risk map: A primary care study protocol
Background: Reducing incidents related to health care interventions to improve patient safety is a health policy priority. To strengthen a culture of safety, reporting incidents is essential. This study aims to define a patient safety risk map using the description and analysis of incidents within a primary care region with a prior patient safety improvement strategy organisationally developed and promoted. Methods: The study will be conducted in two phases: (1) a cross-sectional descriptive observational study to describe reported incidents; and (2) a quasi-experimental study to compare reported incidents. The study will take place in the Camp de Tarragona Primary Care Management (Catalan Institute of Health). In Phase 1, all reactive notifications collected within one year (2018) will be analysed; during Phase 2, all proactive notifications of the second and third weeks of June 2019 will be analysed. Adverse events will also be assessed. Phases 1 and 2 will use a digital platform and the proactive tool proSP to notify and analyse incidents related to patient safety. Expected Results: To obtain an up-to-date, primary care patient safety risk map to prioritise strategies that result in safer practices. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Scientific exploitation of PAZ products in coastal surveillance and monitoring tasks
Revista oficial de la Asociación Española de Teledetección[EN] PAZ mission appears due to the need of a Spanish SAR satellite able to provide radar image products for security and defense, civil and scientific users. INTA is responsible for the technical direction of the Ground Segment, as well as the development of the Calibration and Validation Centre and the scientific exploitation. The ‘Demonstrator of Maritime SAR Applications’ is proposed as an answer to detection tasks in maritime synthetic aperture radar imagery, which are not completely solved yet. DeMSAR has been developed in the framework of a contract between the Spanish National Institute for Aerospace Technology (INTA) and the University of Alcalá. It is intended to be used as a demonstrator of the capabilities of the airborne SAR prototypes of INTA as well as for PAZ, the Spanish SAR satellite. With two operation modes, an automatic ship detector and a toolboxes mode, DeMSAR offers the user a high flexibility in SAR data processing tasks such as speckle filtering, coastline detection, land mask estimation and ship detection and characterization.[ES] La misión PAZ surge ante la necesidad de un satélite SAR español que pueda proporcionar productos imagen radar para usuarios de seguridad y defensa, civiles y científicos. INTA es el responsable de la dirección técnica del Segmento Terreno, así como del desarrollo y operación del Centro de Calibración y Validación y de la Explotación Científica. Dentro de este ámbito de explotación, se desarrolla un demostrador de aplicaciones SAR marítimas (DeMSAR) como herramienta robusta capaz de llevar a cabo tareas de detección sobre la superficie marina, empleando las imágenes adquiridas por radares de apertura sintética. Se desarrolla bajo un marco de colaboración entre el INTA y la Universidad de Alcalá con el fin de convertirse en un demostrador de las capacidades de los sistemas aerotransportados de INTA y, en el futuro, para procesar los datos adquiridos por el sensor PAZ. Con capacidad de operar en modo automático de detección de barcos o mediante librerías de procesado SAR, DeMSAR ofrece una gran versatilidad al usuario en tareas de procesado tales como filtrado de ruido speckle, detección de líneas de costa, estimación de máscaras de tierra y detección y caracterización de barcos.Jarabo, M.; González, M.; De La Mata, D.; Martín De Nicolás, J.; Del Rey, N.; Bárcena, J.; Peláez, V. (2014). Explotación científica de productos PAZ en tareas de vigilancia y monitorización costera. Revista de Teledetección. (41):97-109. doi:10.4995/raet.2014.2287.SWORD9710941Comaniciu, D., & Meer, P. (2002). Mean shift: a robust approach toward feature space analysis. IEEE Transactions on Pattern Analysis and Machine Intelligence, 24(5), 603-619. doi:10.1109/34.1000236Duda, R. O. & Hart, P. E., 1973. Pattern classification and scene analysis. Wiley.Mallat, S., 2008. A wavelet tour of signal processing. 3rd Edition. Academic Press
Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea
An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site
of the ANTARES neutrino telescope near Toulon, France, thus providing a unique
opportunity to compare high-resolution acoustic and optical observations
between 70 and 170 m above the sea bed at 2475 m. The ADCP measured downward
vertical currents of magnitudes up to 0.03 m s-1 in late winter and early
spring 2006. In the same period, observations were made of enhanced levels of
acoustic reflection, interpreted as suspended particles including zooplankton,
by a factor of about 10 and of horizontal currents reaching 0.35 m s-1. These
observations coincided with high light levels detected by the telescope,
interpreted as increased bioluminescence. During winter 2006 deep dense-water
formation occurred in the Ligurian subbasin, thus providing a possible
explanation for these observations. However, the 10-20 days quasi-periodic
episodes of high levels of acoustic reflection, light and large vertical
currents continuing into the summer are not direct evidence of this process. It
is hypothesized that the main process allowing for suspended material to be
moved vertically later in the year is local advection, linked with topographic
boundary current instabilities along the rim of the 'Northern Current'.Comment: 30 pages, 7 figure
Measurement of Atmospheric Neutrino Oscillations with the ANTARES Neutrino Telescope
The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total
live time of 863 days, are used to measure the oscillation parameters of
atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20
GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon
neutrinos of such energies crossing the Earth. The parameters determining the
oscillation of atmospheric neutrinos are extracted by fitting the event rate as
a function of the ratio of the estimated neutrino energy and reconstructed
flight path through the Earth. Measurement contours of the oscillation
parameters in a two-flavour approximation are derived. Assuming maximum mixing,
a mass difference of eV is
obtained, in good agreement with the world average value.Comment: 9 pages, 5 figure
Hidratos de gas marinos: ¿un recurso futuro de gas natural para Europa? M.
Los hidratos de gas son compuestos cristalinos donde una molécula de gas, principalmente metano, queda atrapada en una red de moléculas de agua en forma de hielo. La importancia de los hidratos de gas en la naturaleza es muy alta ya que constituye una fuente alternativa de energía y a su vez juegan un papel importante en el delicado equilibrio del clima a nivel global y en los riesgos geológicos en el ámbito marino. La acción COST MIGRATE está diseñada con el fin de integrar la experiencia de un gran número de grupos de investigación europeos y agentes del sector para promover el desarrollo de conocimientos multidisciplinarios sobre el potencial de los hidratos de gas como fuente de energía en Europa. Dos de los objetivos de esta acción son realizar un inventario europeo de hidratos de gas explotables y evaluar los riesgos ambientales. En este trabajo se muestran los principales indicios de hidratos de gas en los márgenes europeos incluida la Península Ibérica, con una primera aproximación sobre el espesor y situación de la zona de estabilidad de hidratos de gas en el margen Ibérico.Gas hydrates are crystalline compounds where a molecule of gas, mainly methane, is trapped in a cage of icewater molecules. The importance of gas hydrates in nature is very high because it is an alternative source of energy and play a major role in the delicate balance of the global climate and in the marine geological risks. MIGRATE COST action is designed to integrate the experience of a large number of European research groups and industrial players to promote the development of multidisciplinary knowledge on the potential of gas hydrates as energy resource in Europe. Two of the objectives of the action aim to estimate the European inventory of exploitable gas hydrates and to assess environmental risks. In this work we show the occurrences of gas hydrates described in European margins including the
Iberian Peninsula, with a first approximation on the thickness and location of the area of stability of gas hydrates in the Iberian margin.COST Action ES1405 (MIGRATE)Versión del edito
A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007
We present the results of the first search for gravitational wave bursts
associated with high energy neutrinos. Together, these messengers could reveal
new, hidden sources that are not observed by conventional photon astronomy,
particularly at high energy. Our search uses neutrinos detected by the
underwater neutrino telescope ANTARES in its 5 line configuration during the
period January - September 2007, which coincided with the fifth and first
science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed
for candidate gravitational-wave signals coincident in time and direction with
the neutrino events. No significant coincident events were observed. We place
limits on the density of joint high energy neutrino - gravitational wave
emission events in the local universe, and compare them with densities of
merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at
http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000
Diet quality index as a predictor of treatment efficacy in overweight and obese adolescents: The EVASYON study
Background & aim: A diet quality index (DQI) is a tool that provides an overall score of an individual''s dietary intake when assessing compliance with food-based dietary guidelines. A number of DQIs have emerged, albeit their associations with health-related outcomes are debated. The aim of the present study was to assess whether adherence to dietary intervention, and the overall quality of the diet, can predict body composition changes. Methods: To this purpose, overweight/obese adolescents (n = 117, aged: 13–16 years; 51 males, 66 females) were recruited into a multi-component (diet, physical activity and psychological support) family-based group treatment programme. We measured the adolescents’ compliance and body composition at baseline and after 2 months (intensive phase) and 13 months (extensive phase) of follow-up. Also, at baseline, after 6 months, and at the end of follow-up we calculated the DQI. Results: Global compliance with the dietary intervention was 37.4% during the intensive phase, and 14.3% during the extensive phase. Physical activity compliance was 94.1% at 2-months and 34.7% at 13months and psychological support compliance were growing over the intervention period (10.3% intensive phase and 45.3% during extensive phase). Adolescents complying with the meal frequency criteria at the end of the extensive phase had greater reductions in FMI z-scores than those did not complying (Cohen''s d = 0.53). A statistically significant association was observed with the diet quality index. DQI-A variation explained 98.1% of BMI z-score changes and 95.1% of FMI changes. Conclusions: We conclude that assessment of changes in diet quality could be a useful tool in predicting body composition changes in obese adolescents involved in a diet and physical activity intervention programme backed-up by psychological and family support
- …