4,153 research outputs found

    Identities of Choi-Lee-Srivastava involving the Euler-Mascheroni’s constant

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    We give an elementary deduction of the Choi-Lee-Srivastava’s identities involving the Euler Mascheroni’s constant, thus from them is immediate the identity of Wilf

    The exergy costs of electrical power, cooling, and waste heat from a hybrid system based on a solid oxide fuel cell and an absorption refrigeration system

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    This paper applies the Exergy Cost Theory (ECT) to a hybrid system based on a 500 kWe solid oxide fuel cell (SOFC) stack and on a vapor-absorption refrigeration (VAR) system. To achieve this, a model comprised of chemical, electrochemical, thermodynamic, and thermoeconomic equations is developed using the software, Engineering Equation Solver (EES). The model is validated against previous works. This approach enables the unit exergy costs (electricity, cooling, and residues) to be computed by a productive structure defined by components, resources, products, and residues. Most importantly, it allows us to know the contribution of the environment and of the residues to the unit exergy cost of the product of the components. Finally, the simulation of different scenarios makes it possible to analyze the impact of stack current density, fuel use, temperature across the stack, and anode gas recirculation on the unit exergy costs of electrical power, cooling, and residues

    Study through Geant4, for Time Resolution characterization of different detectors arrays coupled with two SiPMs, as a function of: the scintillator plastic material, its volumetric dimensions and the location of the radiation emission source

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    The high time resolution detectors are relevant in those experiments or simulations were the particles to detect, have a very short time of flight (TOF), and due this it´s required that the detections times are ranged between ns. & ps.Using Geant4 software, it was made thirty simulations of coupled detectors to plastic scintillators with two silicon photomultipliers (SiPMs) located on the scintillator’s central sides. To characterize the time resolution, it was required to quantify the optical photons that reach the Score in a certain time, which are generated by muons on the surface of the plastic scintillator. Different configurations of muon beams were simulated at energy of 1 GeV, to interact with the configuration of the scintillator material of its corresponding arrangement. The simulations were made varying three parameters: the scintillator material “BC404 & BC422”, its size, and the location of the radiation source. Fifteen simulations correspond to BC404 material & fifteen simulations to BC422 material respectively. The first five simulations consisted in varying the scintillator’s volumetric size and collocate the muons beam guided randomly distributed over it, the next five simulations differentiate from setting up a directly centered beam, and the last five simulations for guide the beam on the left lower corner of each scintillator.The best time resolution achieved was σ= 8.67 +/− 0.26 ps., reported by the detector with BC422 scintillator material which has a volume of 20x20x3 mm3

    Fundamental care and knowledge interests: implications for nursing science

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    Aims and objectives: The aim of this discursive paper was to characterize the intra-theoretical interests of knowledge in nursing science as an epistemological framework for fundamental care. Background: For Jürgen Habermas, theory does not separate knowledge interests from life. All knowledge, understanding and human research is always interested. Habermas formulated the knowledge interests in empirical-analytical, historical hermeneutic and critical social sciences; but said nothing about health sciences and nursing science. Design: Discursive paper. Results: The paper is organised into five sections that develop our argument about the implications of the Habermasian intra theoretical interests in nursing science and fundamental care: the persistence of a technical interest, the predominance of a practical interest, the importance of an emancipatory interest, “being there” to understand individuals’ experience and an “existential crisis” that uncovers the individual’s subjectivity. Conclusions: The nursing discipline can take on practical and emancipatory interests (together with a technical interest) as its fundamental knowledge interests. Nurses’ privileged position in the delivery of fundamental care gives them the opportunity to gain a deep understanding of the patient’s experience and illness process through physical contact and empathic communication. Relevance to clinical practice and nursing research: In clinical, academic and research environments, nurses should highlight the importance of fundamental care, showcasing the value of practical and emancipatory knowledge. This process could help to improve nursing science’s leadership, social visibility and idiosyncrasy

    Seguimiento de la productividad en obra: técnicas de medición de rendimientos de mano de obra

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    Management systems often present few, since those systems don't adopt control indexes like productivity, which prevents form identifying and defining (from both the systematic and systemic point of view) the problems that require taking corrective and mitigating actions [1]. Methodologies such as "Lean Construction" are based on the management of processes, to maximize revenues and minimize costs, here the improvement of productivity becomes an important parameter for the management system; focusing on the verification of both the process and the product, leaving behind the typical tendency of verifying only results, that is the tendency for control techniques [2]. This study pretends to identify the controlling techniques that should be used when referring to productivity as the quality management control index.En todo sistema de gestión, la planeación sirve como marco de referencia a los programas de control. Adoptar buenas metodologías de seguimiento que acompañen a los procesos de planeación, con miras a lograr un buen desempeño en la gestión y alcanzar las metas deseadas, es una necesidad latente. Aunque en las nuevas metodologías de gestión se hace ya explícita esta necesidad, es muy frecuente encontrar dificultades en los procesos de seguimiento de obra, al no emplearse indicadores adecuados que identifiquen, sistemática y sistémicamente, situaciones importantes que requieran corrección y/o mitigación [1]. La mayoría de las metodologías modernas de mejoramiento basan su estrategia buscando maximizar valor y minimizar pérdidas, razón por la cual, la productividad es uno de los indicadores importantes que mide el desempeño de una buena gestión. Este enfoque, es un planteamiento estratégico orientado hacia los procesos, donde prevalece la verificación y el aseguramiento del procedimiento y el resultado, más allá del viejo esquema de solo verificar resultados [2]. El presente trabajo apunta hacia metodologías de seguimiento, que definan a la productividad, como un indicador significativo de gestión y control en las obras de construcción, en especial la productividad de las cuadrillas de trabajo.&nbsp

    Seguimiento de la productividad en obra: técnicas de medición de rendimientos de mano de obra

    Get PDF
    Management systems often present few, since those systems don't adopt control indexes like productivity, which prevents form identifying and defining (from both the systematic and systemic point of view) the problems that require taking corrective and mitigating actions [1]. Methodologies such as "Lean Construction" are based on the management of processes, to maximize revenues and minimize costs, here the improvement of productivity becomes an important parameter for the management system; focusing on the verification of both the process and the product, leaving behind the typical tendency of verifying only results, that is the tendency for control techniques [2]. This study pretends to identify the controlling techniques that should be used when referring to productivity as the quality management control index.En todo sistema de gestión, la planeación sirve como marco de referencia a los programas de control. Adoptar buenas metodologías de seguimiento que acompañen a los procesos de planeación, con miras a lograr un buen desempeño en la gestión y alcanzar las metas deseadas, es una necesidad latente. Aunque en las nuevas metodologías de gestión se hace ya explícita esta necesidad, es muy frecuente encontrar dificultades en los procesos de seguimiento de obra, al no emplearse indicadores adecuados que identifiquen, sistemática y sistémicamente, situaciones importantes que requieran corrección y/o mitigación [1]. La mayoría de las metodologías modernas de mejoramiento basan su estrategia buscando maximizar valor y minimizar pérdidas, razón por la cual, la productividad es uno de los indicadores importantes que mide el desempeño de una buena gestión. Este enfoque, es un planteamiento estratégico orientado hacia los procesos, donde prevalece la verificación y el aseguramiento del procedimiento y el resultado, más allá del viejo esquema de solo verificar resultados [2]. El presente trabajo apunta hacia metodologías de seguimiento, que definan a la productividad, como un indicador significativo de gestión y control en las obras de construcción, en especial la productividad de las cuadrillas de trabajo.&nbsp

    Co-infections and superinfections complicating COVID-19 in cancer patients: A multicentre, international study

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    Coronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Complicacions infeccioses; CàncerCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Complicaciones infecciosas; CáncerCoronavirus SARS-CoV-2; COVID-19; 2019-nCoV; Infectious complications; CancerBackground We aimed to describe the epidemiology, risk factors, and clinical outcomes of co-infections and superinfections in onco-hematological patients with COVID-19. Methods International, multicentre cohort study of cancer patients with COVID-19. All patients were included in the analysis of co-infections at diagnosis, while only patients admitted at least 48 h were included in the analysis of superinfections. Results 684 patients were included (384 with solid tumors and 300 with hematological malignancies). Co-infections and superinfections were documented in 7.8% (54/684) and 19.1% (113/590) of patients, respectively. Lower respiratory tract infections were the most frequent infectious complications, most often caused by Streptococcus pneumoniae and Pseudomonas aeruginosa . Only seven patients developed opportunistic infections. Compared to patients without infectious complications, those with infections had worse outcomes, with high rates of acute respiratory distress syndrome, intensive care unit (ICU) admission, and case-fatality rates. Neutropenia, ICU admission and high levels of C-reactive protein (CRP) were independent risk factors for infections. Conclusions Infectious complications in cancer patients with COVID-19 were lower than expected, affecting mainly neutropenic patients with high levels of CRP and/or ICU admission. The rate of opportunistic infections was unexpectedly low. The use of empiric antimicrobials in cancer patients with COVID-19 needs to be optimized.This study was supported by the Spanish Plan Nacional de IDi 2013-2016, Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, and the Spanish Network for Research in Infectious Diseases (REIPI grant: RD16/0016/0001). It was also co-financed by the European Development Regional Fund ‘A Way to Make Europe’, Operational Programme Smart Growth 2014-2020

    Parameters of Herbig Ae/Be and Vega-type stars

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    This work presents the determination of the effective temperature, gravity, metallicity, mass, luminosity and age of 27 young early-type stars, most of them in the age range 1-10 Myr, and three -suspected- hot companions of post-T Tauri stars belonging to the Lindroos binary sample. Most of these objects show IR excesses in their spectral energy distributions, which are indicative of the presence of disks. The work is relevant in the fields of stellar physics, physics of disks and formation of planetary systems. Spectral energy distributions and mid-resolution spectra were used to estimate the effective temperature. The comparison of the profiles of the Balmer lines with synthetic profiles provides the value of the stellar gravity. High-resolution optical observations and synthetic spectra are used to estimate the metallicity, [M/H]. Once these three parameters are known for each star, evolutionary tracks and isochrones provide estimations of the mass, luminosity, age and distance (or upper limits in some cases). The method is original in the sense that it is distance-independent, i.e. the estimation of the stellar parameters does not require, as it happens in other works, the knowledge of the distance to the object. A detailed discussion on some individual objects, in particular VV Ser, RR Tau, 49 Cet and the three suspected hot companions of post-T Tauris, is presented. The paper also shows the difficulty posed by the morphology and behaviour of the system star+disk in the computation of the stellar parameters.Comment: 18 pages, 11 figure
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