Reseña de herramientas de SIG libre

Este artículo tiene como objetivo recopilar, en el menor espacio posible, el abanico de opciones de software FOSS4G disponible actualmente. La reseña también se encuentra publicada en wiki.osgeo.org/wiki/Reseñas_FOSS4G.Peer Reviewe

Geometric thermodynamics: black holes and the meaning of the scalar curvature

In this paper we show that the vanishing of the scalar curvature of Ruppeiner-like metrics does not characterize the ideal gas. Furthermore, we claim through an example that flatness is not a sufficient condition to establish the absence of interactions in the underlying microscopic model of a thermodynamic system, which poses a limitation on the usefulness of Ruppeiner's metric and conjecture. Finally, we address the problem of the choice of coordinates in black hole thermodynamics. We propose an alternative energy representation for Kerr-Newman black holes that mimics fully Weinhold's approach. The corresponding Ruppeiner's metrics become degenerate only at absolute zero and have non-vanishing scalar curvatures.Comment: LaTeX file, no figure

The Differentiation Syndrome in Patients with Acute Promyelocytic Leukemia: Experience of the Pethema Group and Review of the Literature

Differentiation syndrome (DS), formerly known as retinoic acid syndrome, is the main life-threatening complication of therapy with differentiating agents (all-trans retinoic acid [ATRA] or arsenic trioxide [ATO]) in patients with acute promyelocytic leukemia (APL). The differentiation of leukemic blasts and promyelocytes induced by ATRA and/or ATO may lead to cellular migration, endothelial activation, and release of interleukins and vascular factors responsible of tissue damage. Roughly one quarter of patients with APL undergoing induction therapy will develop the DS, characterized by unexplained fever, acute respiratory distress with interstitial pulmonary infiltrates, and/or a vascular capillary leak syndrome leading to acute renal failure. Although the development of the DS, particularly of the severe form, is still associated with a significant increase in morbidity and mortality during induction, the early administration of high-dose dexamethasone at the onset of the first symptoms seems likely to have dramatically reduced the mortality rate of this complication. In this article, we will review the clinical features, incidence, prognostic factors, management, and outcome of the DS reported in the scientific literature. We will make focus in the experience of the three consecutive Programa Español de Tratamientos en Hematología trials (PETHEMA LPA96, LPA99, and LPA2005), in which more than one thousand patients were treated with ATRA plus idarubicin for induction

Individual differences in arithmetic fluency

Este estudio contrasta la hipótesis de que las dificultades que tienen algunos sujetos en el dominio de las tablas de multiplicar se deban a su incapacidad para afrontar la interferencia. Los resultados no muestran diferencias en medidas de interferencia en un tarea de recuerdo serial entre sujetos con alta y baja habilidad en la resolución de multiplicaciones. Sin embargo, se encuentran diferencias asociadas a su dominio de las representaciones numéricas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Ministerio de Economía y Competitividad. Proyecto PSI-2012-38423

Absorción saturable de Grafeno para Láser mode-locked

Problem: Since the first successful exfoliation of monolayer graphene in 2004 [1] (for which the Nobel prize was awarded in 2008), research interest in this 2D material has surged exponentially. Graphene, consisting of a twodimensional layer of carbon atoms arranged in a hexagonal lattice, behaves distinctly different from regular 3D materials. Not only does graphene have unseen mechanical properties, (one layer of graphene can carry the weight of a cat!) the material also has extraordinary electrical and optical properties, mainly originating from its linear and gapless band structure [2] [3]. A graphene monolayer absorbs 2.3% of the light passing through, in absolute numbers this is small, graphene could thus be an excellent transparent contact. However considering the monolayer thickness, 2.3% is very large and indicates the strong lightmatter interaction, which can be exploited for light detection [4] or modulation [5]. Due to this strong interaction, it has been observed that once optical intensity reaches a certain threshold saturable absorption takes place: band filling at these high optical intensities causes the absorption of graphene to decrease. This phenomenon can be exploited for the modelocking of lasers, a technique used to produce extremely short (ps to even fs, 10^12 of a second!) and coherent light pulses. Graphene has already been successfully used for modelocking fiber lasers, however it can also be used to make chip scale femtosecond lasers by depositing on integrated silicon waveguides. Researchers at UGent have, in close cooperation with imec, been working on the integration of graphene with photonic structures on a SilicononInsulator (SOI) waveguide. On these hybrid grapheneSOI structures, we recently experimentally demonstrated electrically tunable saturable absorption [6]. This principle can potentially be used for realizing integrated spontaneously modelocked lasers with an electrically tunable pulse duration, making the dream of a ultrashort chip scale femtosecond laser almost a reality. Objective: The proposed work extrapolates on the saturable absorption work presented above. The aim will be to further characterize the saturable absorption in hybrid grapheme-SOI or grapheme-SiN waveguides, and to explore the feasibility of mode-locking a fiber laser using graphene, possibly with tunable properties. As the dynamics of a mode-locked laser are highly dependent of the characteristics of the cavity (dispersion, nonlinear effects ¿), as well as the saturable absorber a large part of the project will consist of simulation, design and development. Depending on the progress of the project, the student will have the freedom to elaborate on the work according to his/her own interests. Possible options contain: developing a better understanding of the carrier dynamics in graphene, thoroughly modelling the behavior of a mode-locked laser, fabrication and design of new hybrid SOI-graphene structures, mode-locking of semiconductor lasers using graphene etc.Problema: Desde la primera exfoliación exitosa del grafeno monocapa en 2004 [1] (para la cual el Premio Nobel fue otorgado en 2008), el interés de la investigación en este material 2D ha aumentado exponencialmente. El grafeno, que consiste en una capa de átomos de carbono dispuestos en una red hexagonal, que se comporta claramente diferente de los materiales 3D regulares. El grafeno no sólo tiene propiedades mecánicas insólitas (una capa de grafeno puede soportar el peso de un gato), sino que también tiene extraordinarias propiedades eléctricas y ópticas, originadas principalmente por una estructura con banda lineal y sin ¿gap¿ [2] [3]. Una monocapa de grafeno absorbe el 2,3% de la luz que pasa, en cifras absolutas esto es pequeño, el grafeno podría ser un excelente material transparente. Sin embargo, teniendo en cuenta el grosor de la monocapa, el 2,3% es muy grande, lo que indica una fuerte interacción luz-materia que puede ser explotada para la detección de luz [4] o la modulación [5]. Debido a esta fuerte interacción, se ha observado que una vez que la intensidad óptica alcanza un cierto umbral, tiene lugar la absorción saturable. El llenado de banda a estas altas intensidades ópticas hace que disminuya la absorción de grafeno. Este fenómeno puede ser explotado para láseres con bloqueo de modo, una técnica utilizada para producir pulsos extremadamente cortos (ps a incluso fs) y de luz coherentes. El grafeno ya ha sido utilizado con éxito para el bloqueo de modos de láseres en fibra, sin embargo también puede ser usado para hacer láseres de femtosegundos de escala de chip depositando sobre guías de onda integradas en silicio. Los investigadores de UGent han trabajado en estrecha cooperación con IMEC en la integración del grafeno con estructuras fotónicas de guías en Silicio sobre aislante (SOI). Sobre estas estructuras híbridas de grafeno-SOI, recientemente hemos demostrado experimentalmente una absorción saturable que se puede regular eléctricamente [6]. Este principio puede utilizarse potencialmente para la realización de láseres integrados con bloqueo de modos espontáneo, que genera un pulso de duración sintonizable eléctricamente. Objetivo: El trabajo propuesto emplea el efecto de absorción saturable del grafeno propuesto, con el objetivo de caracterizar la absorción saturable en guías de onda híbridas grafeno-SOI o grafeno-SiN y para explorar la viabilidad de un láser de fibra con bloqueo de modos usando grafeno, posiblemente con propiedades sintonizables. Como la dinámica de láser con bloque de modos es altamente dependiente de las características de la cavidad (dispersión, los efectos no lineales, ... ), así como de la saturación del absorbedor, una gran parte del proyecto consistirá en su simulación, diseño y desarrollo. En función de la evolución del proyecto, el estudiante tendrá la libertad para elaborar más detalles sobre el trabajo en función de sus propios intereses. Las posibles opciones incluyen el desarrollo de una mejor comprensión de la dinámica de cargas en el grafeno, modelado a fondo el comportamiento de un láser con bloqueo de modos, la fabricación y diseño de nuevas estructuras híbridas SOI-grafeno, bloqueo de modos en láser de semiconductor empleando grafeno, etc.Montesinos Ballester, M. (2017). Absorción saturable de Grafeno para Láser mode-locked. http://hdl.handle.net/10251/91809TFG

Properties of the Tcc(3875)+T_{cc}(3875)^+ and Tcˉcˉ(3875)−T_{\bar c\bar c}(3875)^- (and their heavy-quark spin partners) in nuclear matter

We discuss the modification of the properties of the tetraquark-like $T_{cc}(3875)^+$ and $T_{\bar c\bar c}(3875)^-$ states in dense nuclear matter. We consider the $T_{cc}^+$ and $T_{\bar c\bar c}^-$ in vacuum as purely isoscalar $D^{\ast} D$ and $\overline{D}{}^{\ast} \overline{D}$ $S$-wave bound states, respectively, dynamically generated from a heavy-quark effective interaction between the charmed mesons. We compute the $D$, $\overline{D}$, $D^*$, and $\overline{D}{}^{*}$ spectral functions embedded in a nuclear medium and use them to determine the corresponding $T_{cc}^+$ and $T_{\bar c\bar c}^-$ self energies and spectral functions. We find important modifications of the $D^{\ast} D$ and $\overline{D}{}^{\ast} \overline{D}$ scattering amplitudes and of the pole position of these exotic states already for $\rho_0/2$, with $\rho_0$ the normal nuclear density. We also discuss the dependence of these results on the $D^{\ast} D$ ($\overline{D}{}^{\ast} \overline{D}$) molecular component in the $T_{cc}^+$ ($T_{\bar c\bar c}^-$ ) wave-function. Owing to the different nature of the $D^{(*)}N$ and $\overline{D}{}^{(*)}N$ interactions, we find characteristic changes of the in-medium properties of the $T_{cc}(3875)^+$ and $T_{\bar c\bar c}(3875)^-$, which become increasingly visible as the density increases. The experimental confirmation of the found distinctive density-pattern will give support to the molecular picture of these tetraquark-like states, since in the case they were colourless compact quark structures the density behaviour of their respective nuclear medium spectral functions would likely be similar. Finally, we perform similar analyses for the isoscalar $J^P=1^+$ heavy-quark spin symmetry partners of the $T_{cc}^+$ ($T_{cc}^{*+}$) and the $T_{\bar c\bar c}^-$ ($T_{\bar c\bar c}^{*-}$) by considering the $D^{*0}D^{*+}$ and $\overline{D}{}^{*0} D^{*-}$ scattering $T-$matrices.Comment: 17 pages, 9 figure

Determining kinetic constants and transport efficiencies at membrane interfaces to optimize the removal/recovery of Cu(II) through lulk liquid membranes containing benzoylacetone as carrier

The removal, separation, and enrichment of heavy metals in aqueous solutions has become a prime concern over the last few decades because of both their adverse effects on the ecosystem and living organisms and their valuable resource character. This paper describes a study to optimize the simultaneous removal/ recovery of Cu(II) from aqueous solutions by bulk liquid membranes, through a facilitated countertransport mechanism using benzoylacetone as a mobile carrier and hydrochloric acid as a stripping agent (protons as counter ions), by analyzing the effect of different operational variables (carrier concentration in membrane phase, stripping agent concentration in product phase, stirring rate, and membrane phase volume) on the removal/recovery kinetics constants and on the transport efficiencies through the feed/membrane and membrane/product interfaces.We would like to thank Mr. A. Guzmán and Mr. J.A. López for manufacturing the experimental cell

Analysis and evaluation of corrosion in naval steels

The corrosion of steel due to seawater is a problem faced by all ships. In this work it has been analyzed two of the variables that most infuence the degradation process of carbon steels in marine environments (pH and chloride concentration), as well as the galvanic couple, which arises when two metals of diferent potential make contact. The study was carried out with two types of steel (S275JR and S235JR) and 15 diferent environments were analyzed (Fig. 1). The progression of corrosion was evaluated in two ways: i) by measuring the mass variation due to the corrosion phenomenon, which was subsequently used to determine the kinetics of the reaction, and ii) visually, by using free software ImageJ. The combined efect of the three variables was analyzed using the Statistics software, performing a factorial analysis in order to obtain response surfaces and their corresponding predictive equations, which allow predicting the efect of corrosion. Finally, in order to observe the diferences between the model obtained and the degree of actual corrosion, both steel types were subjected to the efect of seawater from the dock of the Naval Academy. Results of the study showed a loss of 0,1 g a week, infuenced by the chloride concentration and the acid environment (Fig. 2). From the data obtained, predictive equations were formulated and compared with experiments in laboratory. After 3 weeks of corrosion induced in laboratory, a deviation of 6,74% between the real and predicted mass of probes was observed for steel S275JR and 1,35% for steel S235JR, which evidence the accuracy of the experiments carried out and gives a valuable tool in order to predict efects of corrosion. Corrosion kinetics showed a degradation of 0,3 mm/year and predictive equations showed a deviation lower than 7% in both steels when compared with experiments in laboratory.Peer Reviewe

Propiedades psicométricas de la escala de hábitos de estudios STUDENTS 7 en estudiantes universitarios del Cono Norte de Lima, 2020

La presente investigación de tipo instrumental tuvo como objetivo determinar las propiedades psicométricas de la escala de hábitos de estudios STUDENT7 de Pereyra en estudiantes universitarios del cono norte de Lima, Perú. La muestra fue de 349 universitarios. Las evidencias de validez de constructo a través del análisis factorial exploratorio AFE y confirmatorio AFC permitieron verificar la pertinencia del modelo teórico para explicar los hábitos de estudios en siete dimensiones de acuerdo al modelo de procesamiento de información de Gagñé (1976). Las evidencias de confiabilidad a través del coeficiente Omega obtuvieron valores entre 0,490 y 0,852. En síntesis, la versión de 26 ítems obtuvo moderado índice de ajuste: x2/gl= 2.20, RMSEA= 0.05, CFI= 0,87, y TLI= 0,85. La versión de 22 ítems obtuvo buen índice de ajuste: x2/gl: 2.06, RMSEA = 0,05, CFI = 0,91, y TLI = 0,90. En conclusión, la escala de hábitos de estudios STUDENTS7 original de 26 ítems y la propuesta en esta tesis de 22 ítems obtuvieron suficientes evidencias de validez y confiabilidad para su aplicación en universitarios