Neutron Star Radius-to-mass Ratio from Partial Accretion Disc Occultation as Measured through Fe Kα\alpha Line Profiles

We present a new method to measure the radius-to-mass ratio (R/M) of weakly magnetic, disc-accreting neutron stars by exploiting the occultation of parts of the inner disc by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low mass X-ray binary systems seen under inclinations higher than ~65 degrees. We analyse a NuSTAR observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-to-noise. Based on an extensive set of simulations we show that large-area X-ray detectors of the future generation could measure R/M to ~2{\div}3% precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods too aim to achieve in the future.Comment: 17 pages, 8 figures; this is a pre-print edition of an article that has been accepted for publication in the Astrophysical Journa

A software engine for multi-criteria decision support in flight management - Use of dynamic cost functions - Architecture and first results

Tactical trajectory optimisation should consider the total expected cost of the flight (fuel and delay). The cost of fuel can be estimated from the expected fuel usage. The cost of delay can be approximated by simple non-linear functions but, we propose a methodology to explicitly consider its different components: passenger related (regulation 261, duty of care, missed connections and soft costs), crew and maintenance, and reactionary costs (delay and curfew). This explicit modelling captures the non-continuous aspects of the cost function, which can significantly impact the optimisation profile, e.g. ensure that missed connections are reduced. The cost of delay, dependent on the arrival time at the gate, can be subject to uncertainties which are inherent (e.g. if a passenger will or not miss a connection) and external (e.g. taxi-in or holding times). Therefore, the optimisation framework should estimate the arrival time to the gate (not the runway) while considering these associated uncertainties. The described architecture models the processes affecting the cost (e.g. considering probabilities of missed connections or explicit propagation of delay) and operational aspects at arrival which impact the realisation of the planned optimised trajectory (holding time, sequencing and merging distance (tromboning), and taxi-in time). The consideration of the operational uncertainties enables the estimation of the probability of achieving the flight on-time performance. All these operational uncertainties are integrated into the cost function producing a total expected cost as a function of arrival to FL100 during the descent at the arrival airport. The trajectory is then optimised in its vertical and speed profile finding the cost index which is expected to minimise the total costs with a simulated annealing framework. The first results presented describe how the cost functions are generated, uncertainties considered and trajectories optimised for a flight in the LEDM-EDDF route

Analisi dei siti web istituzionali dei musei statali italiani di proprietà del Ministero dei Beni e delle Attività Culturali (MIBAC) nei capoluoghi di provincia

Today's society is increasingly devoted to the use of the network to find information and is often influenced by the viral and captivating disclosure of news, so websites and Facebook pages stand today as the main channels of communication. Especially the museums, should therefore focus a great deal on these channels in order to perform their marketing activities both for an endogenous improvement of their services, through the evaluation of users, and for an optimal fruition of their resources by visitors. This article, in this general framework, proposes the results of a field survey conducted to evaluate the digital and communicative skills of Italian museums, through the analysis of the relevant institutional websites and their official Facebook pages

Pancreatic Progenitor Commitment Is Marked by an Increase in Ink4a/Arf Expression

The identification of the molecular mechanisms controlling early cell fate decisions in mammals is of paramount importance as the ability to determine specific lineage differentiation represents a significant opportunity for new therapies. Pancreatic Progenitor Cells (PPCs) constitute a regenerative reserve essential for the maintenance and regeneration of the pancreas. Besides, PPCs represent an excellent model for understanding pathological pancreatic cellular remodeling. Given the lack of valid markers of early endoderm, the identification of new ones is of fundamental importance. Both products of the Ink4a/Arf locus, in addition to being critical cell-cycle regulators, appear to be involved in several disease pathologies. Moreover, the locus’ expression is epigenetically regulated in ES reprogramming processes, thus constituting the ideal candidates to modulate PPCs homeostasis. In this study, starting from mouse embryonic stem cells (mESCs), we analyzed the early stages of pancreatic commitment. By inducing mESCs commitment to the pancreatic lineage, we observed that both products of the Cdkn2a locus, Ink4a and Arf, mark a naïve pancreatic cellular state that resembled PPC-like specification. Treatment with epi-drugs suggests a role for chromatin remodeling in the CDKN2a (Cycline Dependent Kinase Inhibitor 2A) locus regulation in line with previous observations in other cellular systems. Our data considerably improve the comprehension of pancreatic cellular ontogeny, which could be critical for implementing pluripotent stem cells programming and reprogramming toward pancreatic lineage commitment

Neutron star radius-To-mass ratio from partial accretion disk occultation as measured through fe kα line profiles

We present a new method to measure the radius-To-mass ratio (R/M) of weakly magnetic, disk-Accreting neutron stars by exploiting the occultation of parts of the inner disk by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low-mass X-ray binary systems seen under inclinations higher than ∼65°. We analyze a Nuclear Spectroscopic Telescope Array observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-To-noise. Based on an extensive set of simulations we show that large-Area X-ray detectors of the future generation could measure R/M to ∼2 ÷ 3% precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods also aim to achieve in the future

Un algoritmo para la identificación de unidades taxonómicas indicadoras y su uso en análisis del estado del ecosistemas

Biological community structure can be used as an ecological state descriptor, and the sensitivity of some taxonomic groups or biological entities to environmental conditions allows for their use as ecological state indicators. This work describes an algorithm developed for the identification of such taxonomic units when comparing environments or ecosystems under different anthropic impacts. Based solely on presence or absence information in a database, the algorithm identifies indicator taxonomic units for each environment, estimates the belonging of any additional samples to a given environment, approximates the ecological niche of any taxonomic unit based on two or more selected environmental factors, and analyzes the frequency of any taxonomic unit in a selected combination of the environmental factors chosen. By using the approximation to the ecological niche of the taxonomic units present, given a new sample, the physicochemical parameters of the environment it was taken can be estimated by the units present in the sample. These analyses can be performed simultaneously for two or more taxonomic units. This work provides a description of how the mathematical method was developed. Based on this methodology, a freely downloadable R package for easy use was developed, (Ecoindicators, DOI: https://github.com/lsaravia/EcoIndicators). One of the advantages of this method, and the R-package mentioned is that it can be used for any ecosystem for which there is a suitable biological dataset associated with environmental factors. In addition, both this mathematical procedure and the package referred to, can be tailored by other researchers to fit their own needs.La estructura de una comunidad biológica puede usarse como un descriptor del estado ecológico, y la sensibilidad de algunos grupos taxonómicos o entidades biológicas a las condiciones ambientales, permite que sean usados como indicadores de dicho estado. Este trabajo describe el desarrollo de un algoritmo para la identificación de tales unidades taxonómicas al comparar ambientes o ecosistemas bajo diferentes impactos antrópicos. Basado únicamente en información de presencia o ausencia en una base de datos, el algoritmo identifica unidades taxonómicas indicadoras de cada ambiente, estima la pertenencia de cualquier muestra adicional a un ambiente dado, aproxima el nicho ecológico de cualquier unidad taxonómica con base en dos o más factores ambientales seleccionados y analiza la frecuencia de cualquier unidad taxonómica en la combinación de los factores ambientales elegidos. Utilizando la aproximación al nicho ecológico de las unidades taxonómicas presentes en la base de datos, dada una nueva muestra, se pueden estimar ciertos parámetros fisicoquímicos del ambiente de donde provino tal muestra a partir de las especies presentes en la misma. Estos análisis se pueden realizar simultáneamente para dos o más unidades taxonómicas. Este trabajo proporciona una descripción de cómo se desarrolló este procedimiento matemático. Con base en la metodología aquí descripta, se desarrolló un paquete R de fácil descarga y uso gratuito (Ecoindicators, DOI: https://github.com/lsaravia/EcoIndicators). Una de las ventajas de este método, y del paquete R mencionado, es que puede usarse para cualquier ecosistema para el que exista un conjunto de datos biológicos adecuados asociados con factores ambientales. Además, tanto este procedimiento matemático como el paquete al que se hace referencia, pueden ser adaptados por otros investigadores para que se ajusten a sus propias necesidades.Fil: de la Vega, Darío Hernán. Universidad Nacional de Luján. Departamento de Ciencias Básicas; ArgentinaFil: Falco, Liliana. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; ArgentinaFil: Saravia, Leonardo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: Sandler, Rosana Veronica. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; ArgentinaFil: Duhour, Andrés Esteban. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; ArgentinaFil: Velazco, Victor Nicolás. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; ArgentinaFil: Coviella, Carlos Eduardo. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; Argentin

Un algoritmo para la identificación de unidades taxonómicas indicadoras y su uso en análisis del estado del ecosistemas

Biological community structure can be used as an ecological state descriptor, and the sensitivity of some taxonomic groups or biological entities to environmental conditions allows for their use as ecological state indicators. This work describes an algorithm developed for the identification of such taxonomic units when comparing environments or ecosystems under different anthropic impacts. Based solely on presence or absence information in a database, the algorithm identifies indicator taxonomic units for each environment, estimates the belonging of any additional samples to a given environment, approximates the ecological niche of any taxonomic unit based on two or more selected environmental factors, and analyzes the frequency of any taxonomic unit in a selected combination of the environmental factors chosen. By using the approximation to the ecological niche of the taxonomic units present, given a new sample, the physicochemical parameters of the environment it was taken can be estimated by the units present in the sample. These analyses can be performed simultaneously for two or more taxonomic units. This work provides a description of how the mathematical method was developed. Based on this methodology, a freely downloadable R package for easy use was developed, (Ecoindicators, DOI: https://github.com/lsaravia/EcoIndicators). One of the advantages of this method, and the R-package mentioned is that it can be used for any ecosystem for which there is a suitable biological dataset associated with environmental factors. In addition, both this mathematical procedure and the package referred to, can be tailored by other researchers to fit their own needs.La estructura de una comunidad biológica puede usarse como un descriptor del estado ecológico, y la sensibilidad de algunos grupos taxonómicos o entidades biológicas a las condiciones ambientales, permite que sean usados como indicadores de dicho estado. Este trabajo describe el desarrollo de un algoritmo para la identificación de tales unidades taxonómicas al comparar ambientes o ecosistemas bajo diferentes impactos antrópicos. Basado únicamente en información de presencia o ausencia en una base de datos, el algoritmo identifica unidades taxonómicas indicadoras de cada ambiente, estima la pertenencia de cualquier muestra adicional a un ambiente dado, aproxima el nicho ecológico de cualquier unidad taxonómica con base en dos o más factores ambientales seleccionados y analiza la frecuencia de cualquier unidad taxonómica en la combinación de los factores ambientales elegidos. Utilizando la aproximación al nicho ecológico de las unidades taxonómicas presentes en la base de datos, dada una nueva muestra, se pueden estimar ciertos parámetros fisicoquímicos del ambiente de donde provino tal muestra a partir de las especies presentes en la misma. Estos análisis se pueden realizar simultáneamente para dos o más unidades taxonómicas. Este trabajo proporciona una descripción de cómo se desarrolló este procedimiento matemático. Con base en la metodología aquí descripta, se desarrolló un paquete R de fácil descarga y uso gratuito (Ecoindicators, DOI: https://github.com/lsaravia/EcoIndicators). Una de las ventajas de este método, y del paquete R mencionado, es que puede usarse para cualquier ecosistema para el que exista un conjunto de datos biológicos adecuados asociados con factores ambientales. Además, tanto este procedimiento matemático como el paquete al que se hace referencia, pueden ser adaptados por otros investigadores para que se ajusten a sus propias necesidades.Fil: de la Vega, Darío Hernán. Universidad Nacional de Luján. Departamento de Ciencias Básicas; ArgentinaFil: Falco, Liliana. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; ArgentinaFil: Saravia, Leonardo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: Sandler, Rosana Veronica. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; ArgentinaFil: Duhour, Andrés Esteban. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; ArgentinaFil: Velazco, Victor Nicolás. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; ArgentinaFil: Coviella, Carlos Eduardo. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas. Laboratorio de Ecología; Argentin

Interaction between linear polarized plane gravitational waves and a plane electromagnetic wave in the electromagnetic-gravity analogue

We study the interaction among gravitational and electromagnetic plane waves by means of an analogue electromagnetic model of gravity, where the gravitational properties are encoded in the electromagnetic properties of a material in flat space-time. In this setup, the variations in the metric tensor produced by the gravitational waves are codified as space-time-varying electromagnetic properties. We used an in-housed code based in the finite-difference time domain method to conduct numerical experiments, where we found that, when a monochromatic gravitational plane wave interacts with a narrow-band electromagnetic plane wave, an infinite number of sidebands, equally separated between themselves, are induced by the gravitational wave. Finally, we discuss possible future applications of this effect as an alternative method to directly detect gravitational waves.Comment: 10 pages, 4 figures, 2 tables. Accepted for publication on Physical Review

Dynamic properties along the neutral line of a delta spot inferred from high-resolution observations

Delta (δ) spots are complex magnetic configurations of sunspots characterized by umbrae of opposite polarity sharing a common penumbra. In order to investigate the fine structure of the region separating the two magnetic polarities of a δ spot, we studied the morphology, the magnetic configuration, and the velocity field in such a region using observations of active region (AR) NOAA 11267 obtained with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish Solar Telescope on 2011 August 6. The analysis of CRISP data shows upflows and downflows of ~ ± 3 km s–1 in proximity of the δ spot polarity inversion line (PIL), and horizontal motions along the PIL of the order of ~1 km s–1. The results obtained from the SIR inversion of CRISP data also indicate that the transverse magnetic field in the brighter region separating the two opposite magnetic polarities of the δ spot is tilted about ~45° with respect to the PIL. Solar Dynamics Observatory/Helioseismic and Magnetic Imager observations confirm the presence of motions of ~ ± 3 km s–1 in proximity of the PIL, which were observed to last 15 hr. From the data analyzed, we conclude that the steady, persistent, and subsonic motions observed along the δ spot PIL can be interpreted as being due to Evershed flows occurring in the penumbral filaments that show a curved, wrapped configuration. The fluting of the penumbral filaments and their bending, continuously increased by the approaching motion of the negative umbra toward the positive one, give rise to the complex line-of-sight velocity maps that we observed. © 2014. The American Astronomical Society. All rights reserved