The principle of maximum entropy explains the cores observed in the mass distribution of dwarf galaxies

Cold dark matter (CDM) simulations predict a central cusp in the mass distribution of galaxies. This prediction is in stark contrast with observations of dwarf galaxies that show a central plateau or "core"in their density distribution. The proposed solutions to this core-cusp problem can be classified into two types. One invokes feedback mechanisms produced by the baryonic component of the galaxies and the other assumes that the properties of the dark matter particle depart from the CDM hypothesis. Here we propose an alternative yet complementary explanation. We argue that cores are unavoidable in the self-gravitating systems of maximum entropy that result from non-extensive statistical mechanics. Their structure follows from the Tsallis entropy, which is attributed to systems with long-range interactions. Strikingly, the mass density profiles predicted by such thermodynamic equilibrium match the observed cores without any adjustment or tuning. Thus, the principle of maximum Tsallis entropy explains the presence of cores in dwarf galaxies.Fil: Sánchez Almeida, Jorge. Instituto Astrofisico de Canarias; España. Universidad de La Laguna; EspañaFil: Trujillo, Ignacio. Instituto Astrofisico de Canarias; España. Universidad de La Laguna; EspañaFil: Plastino, Ángel Ricardo. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Bioinvestigaciones (Sede Pergamino); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires; Argentin

Machine learning in APOGEE: Unsupervised spectral classification with KK-means

The data volume generated by astronomical surveys is growing rapidly. Traditional analysis techniques in spectroscopy either demand intensive human interaction or are computationally expensive. In this scenario, machine learning, and unsupervised clustering algorithms in particular offer interesting alternatives. The Apache Point Observatory Galactic Evolution Experiment (APOGEE) offers a vast data set of near-infrared stellar spectra which is perfect for testing such alternatives. Apply an unsupervised classification scheme based on $K$-means to the massive APOGEE data set. Explore whether the data are amenable to classification into discrete classes. We apply the $K$-means algorithm to 153,847 high resolution spectra ($R\approx22,500$). We discuss the main virtues and weaknesses of the algorithm, as well as our choice of parameters. We show that a classification based on normalised spectra captures the variations in stellar atmospheric parameters, chemical abundances, and rotational velocity, among other factors. The algorithm is able to separate the bulge and halo populations, and distinguish dwarfs, sub-giants, RC and RGB stars. However, a discrete classification in flux space does not result in a neat organisation in the parameters space. Furthermore, the lack of obvious groups in flux space causes the results to be fairly sensitive to the initialisation, and disrupts the efficiency of commonly-used methods to select the optimal number of clusters. Our classification is publicly available, including extensive online material associated with the APOGEE Data Release 12 (DR12). Our description of the APOGEE database can enormously help with the identification of specific types of targets for various applications. We find a lack of obvious groups in flux space, and identify limitations of the $K$-means algorithm in dealing with this kind of data.Comment: 23 pages, 24 images and online materia

Liposarcoma mixoide retroperitoneal, a propósito de un caso.

Ratient 72 year oíd married man, a farmer, has lived for a year in the U.S. North American debut six months ago with abdominal pain and a month before the medical con sultaron is accompanied by abdominal fullness. Physical examination an abdominal mass that occupies much of the left abdomen. Abdominal ultrasound and CT sean reported as a dependent tumor of the páncreas. Laparotomy was performed, being retroperitoneal tumor is removed completely with the tail of the páncreas which is attached, with histological diagnosis of myxoid liposarcoma. Tothe case conducted a review on the frequency, current status of diagnosis, treatment and prognosis.Paciente de 72 años varón casado, agricultor, residente desde hace un año en los EE.UU. de Norteamérica que hace seis meses debuta con dolor abdominal y un mes antes de la consulta médica se acompaña de sensación de plenitud abdominal. Al examen físico presenta una masa abdominal que ocupa gran parte del hemiabdomen izquierdo. Eco y TAC de abdomen reportan como una tumoración dependiente de páncreas. Se realiza laparotomía, encontrándose tumoración retroperitoneal que se extrae totalmente con la cola del páncreas a la cual se halla adherida, con diagnóstico anatomo patológico de liposarcoma mixoide. A propósito del caso realizamos, una revisión sobre la frecuencia, estado actual de su diagnóstico, tratamiento y pronóstic

Design and evaluation of a natural interface for remote operation of underwater roter

Nowadays, an increasing need of intervention robotic systems can be observed in all kind of hazardous environments. In all these intervention systems, the human expert continues playing a central role from the decision making point of view. For instance, in underwater domains, when manipulation capabilities are required, only Remote Operated Vehicles, commercially available, can be used, normally using master-slave architectures and relaying all the responsibility in the pilot. Thus, the role played by human- machine interfaces represents a crucial point in current intervention systems. This paper presents a User Interface Abstraction Layer and introduces a new procedure to control an underwater robot vehicle by using a new intuitive and immersive interface, which will show to the user only the most relevant information about the current mission. Finally, some experiments have been carried out to compare a traditional setup and the new procedure, demonstrating reliability and feasibility of our approach.This research was partly supported by Spanish Ministry of Research and Innovation DPI2011-27977-C03 (TRITON Project)

A natural interface for remote operation of underwater robots

Nowadays, an increasing need of intervention robotic systems can be observed in all kind of hazardous environments. In all these intervention systems, the human expert continues playing a central role from the decision-making point of view. For instance, in underwater domains, when manipulation capabilities are required, only Remote Operated Vehicles, commercially available, can be used, normally using master-slave architectures and relaying all the responsibility in the pilot. Thus, the role played by human- machine interfaces represents a crucial point in current intervention systems. This paper presents a User Interface Abstraction Layer and introduces a new procedure to control an underwater robot vehicle by using a new intuitive and immersive interface, which will show to the user only the most relevant information about the current mission. We conducted an experiment and found that the highest user preference and performance was in the immersive condition with joystick navigation.This research was partly supported by Spanish Ministry of Research and Innovation DPI2011-27977-C03 (TRITON Project)

Hydrothermal carbonization of olive tree pruning as a sustainableway for improving biomass energy potential: effect of reaction parameters on fuel properties

Hydrothermal carbonization (HTC) allows the conversion of organic waste into a solid product called hydrochar with improved fuel properties. Olive tree pruning biomass (OTP), a very abundant residue in Mediterranean countries, was treated by HTC to obtain a solid fuel similar to coal that could be used in co-combustion processes. Three different reaction temperatures (220, 250, and 280 °C) and reaction times (3, 6, and 9 h) were selected. The hydrochars obtained were extensively analyzed to study their behavior as fuel (i.e., ultimate, proximate, fiber and thermogravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), activation energy, and combustion performance). The concentrations of cellulose, hemicellulose, and lignin in the samples depict a clear and consistent trend with the chemical reactions carried out in this treatment. Regarding O/C and H/C ratios and HHV, the hydrochars generated at more severe conditions are similar to lignite coal, reaching values of HHV up to 29.6 MJ kg-1. The higher stability of the solid is reflected by the increase of the activation energy (≈60 kJ mol-1), and ignition temperatures close to 400 °C. With this, HTC is a proper thermal treatment for the management of raw OTP biomass and its further conversion into a solid biofuel.Judith González-Arias would like to thank the Junta de Castilla y León (Consejería de Educación) fellowship, Orden EDU/1100/2017, cofinanced by the European Social Fund.info:eu-repo/semantics/publishedVersio

El comportamiento del consumo en servicio de alimentos y bebidas, alojamiento y transporte turístico durante la pandemia COVID-19

Introduction. This article focuses on the study of the profile of the consumer of food and beverage services, accommodation and tourist transport in the province of Tungurahua from the COVID-19 pandemic, after the state of emergency, for which it is necessary to identify the visitor behavior patterns, consider the conditions, factors and image that determine the perception and / or preference and that influence the consumption decision. Objective. Analyze the differences in the consumption behavior of visitors in food and beverage services, accommodation and tourist transport. Methodology. The research is basic and inductive, follows a quantitative route, reaches a descriptive level, is based on a deep bibliographic-documentary study and a cross-sectional ex post facto fieldwork design, with a simple random sampling. The profile of the consumer of tourist services in the province of Tungurahua is modeled by the tree classification method. Results. The level of education is the demographic variable that most influences the factors that influence the frequency of consumption by customers of restaurants and cafeterias. The behavior of the consumption of the accommodation service is marked by the preference of spending the night with the family or partner, being the woman who mostly makes this decision. The behavior of tourist transport consumption is manifested with the preference of comfort and safety over audio and video technology or innovation; and, the cost does not determine the hiring of the service. Conclusion. The factor that decides the consumption of food and beverage service, accommodation and tourist transport is the application of biosafety protocols, information that was used for the execution of community service practice projects.Introducción. El presente artículo se centra en el estudio del perfil del consumidor de servicios de alimentos y bebidas, alojamiento y transporte turístico en la provincia de Tungurahua a partir de la pandemia COVID-19, posterior al estado de excepción, para lo que es necesario identificar los patrones de comportamiento de los visitantes, considerar las condiciones, los factores e imagen que determinan la percepción y/o preferencia y que influyen en la decisión de consumo. Objetivo. Analizar las diferencias del comportamiento de consumo de los visitantes en servicios de alimentos y bebidas, alojamiento y transporte turístico. Metodología. La investigación es básica e inductiva, sigue una ruta cuantitativa, alcanza un nivel descriptivo, se sustenta en un profundo estudio bibliográfico – documental y con un diseño de un trabajo de campo ex post facto de corte transversal, con un muestreo aleatorio simple. El perfil del consumidor de servicios turísticos en la provincia de Tungurahua se modela mediante el método de clasificación del árbol. Resultados. El nivel de estudios es la variable demográfica que más incide en los factores que influyen en la frecuencia de consumo de los clientes de restaurantes y cafeterías. El comportamiento del consumo del servicio de alojamiento está marcado por la preferencia de la pernoctación con la familia o pareja, siendo la mujer quien toma mayoritariamente esta decisión. El comportamiento del consumo del transporte turístico se manifiesta con la preferencia de la comodidad y seguridad ante tecnología de audio y vídeo o innovación; y, el costo no determina la contratación del servicio. Conclusión. El factor que decide el consumo de servicio de alimentos y bebidas, alojamiento y transporte turístico es la aplicación de protocolos de bioseguridad, información que fue utilizada para la ejecución de proyectos de prácticas de servicio comunitario