1,738 research outputs found

    Entanglement of a chiral fermion on the torus

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    In this paper we present the detailed calculation of a new modular Hamiltonian, namely that of a chiral fermion on a circle at non-zero temperature. We provide explicit results for an arbitrary collection of intervals, which we discuss at length by checking against known results in different limits and by computing the associated modular flow. We also compute the entanglement entropy, and we obtain a simple expression for it which appears to be more manageable than those already existing in the literature.Fil: Blanco, David Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Garbarz, Alan Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Pérez Nadal, Guillem. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

    Local temperatures and local terms in modular Hamiltonians

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    We show there are analogs to the Unruh temperature that can be defined for any quantum field theory and region of the space. These local temperatures are defined using relative entropy with localized excitations. We show that important restrictions arise from relative entropy inequalities and causal propagation between Cauchy surfaces. These suggest a large amount of universality for local temperatures, especially the ones affecting null directions. For regions with any number of intervals in two spacetime dimensions, the local temperatures might arise from a term in the modular Hamiltonian proportional to the stress tensor. We argue this term might be universal, with a coefficient that is the same for any theory, and check analytically and numerically that this is the case for free massive scalar and Dirac fields. In dimensions d≥3, the local terms in the modular Hamiltonian producing these local temperatures cannot be formed exclusively from the stress tensor. For a free scalar field, we classify the structure of the local terms.Instituto de Física La Plat

    Effectiveness of different disinfection techniques of the root canal in the elimination of a multi-species biofilm

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    The purpose of the study was to evaluate the effectiveness of different root canal disinfection techniques in the elimination of a multi-species biofilm from inside the root canal. Fifty mandibular first premolars were used in the present study, standardized to 11mm of root length, and instrumented with a reciprocation system Reciproc, (VDW GmbH, Munich, Germany) to a #50. Longitudinally sectioned halves of the roots were obtained and washed with NaOCl 4%, EDTA 17% and 5% sodium thiosulfate, and sterilized by autoclaving for 15 minutes at 121°C. A multi-species biofilm broth was developed with three strains of bacteria under laboratory conditions: Enterococcus faecalis ATTC 29212, Eikenella corrodens ATTC 23834, Streptococcus anginosus ATTC 33397. Roots were autoclaved and transferred to the broth for 4 days and then were subjected to either disinfection with sodium hypochlorite 4% and XP-endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland) or chlorhexidine 2% with and without activation with XP-endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland). The evaluations of the biofilm elimination showed results that indicate that the 4% sodium hypochlorite group with positive pressure irrigation presented significant differences with the group that had irrigation with sodium hypochlorite activated with XP-endo Finisher and the chlorhexidine groups to 2% (P<0.05). Chlorhexidine 2% activated with the XP-endo Finisher does not exert elimination or improved cleaning effect on the multi-species biofilm. Activation of sodium hypochlorite 4% improved the elimination of the multi-species biofilm

    Accurate rotor speed estimation for low-power wind turbines

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    Small grid-tied wind turbines based on permanent magnet generators often use a cost-effective power converter topology consisting of a passive rectifier, a boost converter, and an H-bridge inverter. Speed or position sensors are rarely used due to cost issues. Model-based estimators relying on electrical magnitudes are used instead. However, such estimators are parameter sensitive, which limit their accuracy. Further concerns arise if these parameters change with the operating condition of the machine, mainly due to temperature. Speed sensorless control using the rectifier voltage ripple is analyzed in this paper. This technique provides good dynamic response and does not depend on machine parameters. Simulations are provided for speed and power tracking comparison with an accurate model-based speed estimation method operating at non-rated parameters. The speed accuracy and power tracking capability of the proposed method are similar to that provided by a speed sensor. This is translated into a 0.9% power increase when the model-based speed estimator shows 9% of error. Experimental results are carried out to test the effect of current and temperature in the estimation, showing temperature insensitivity and some distortion due to fast current transients. A speed estimation accuracy of zero mean error and 1.7% standard error is experimentally obtained in the regular operation of the wind turbin

    Planteamiento de metodología para el monitoreo y control en la fase de construcción de proyectos de infraestructura educativa teniendo en cuenta la guía Pmbok sexta edición - caso de estudio: proyecto centro educativo rural CER el Carmen, ubicado en zona rural del municipio de Remedios – Antioquia

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    Línea de investigaciónEl desarrollo del presente trabajo de grado tiene la finalidad de suministrar los recursos metodológicos para abordar la ejecución de proyectos de construcción dentro del marco del proceso de monitoreo y control de la guía PMBOK 6ta edición. Por tanto, se propone mediante este grupo de procesos identificar las áreas en las que el plan de desarrollo del proyecto de construcción requiere cambios (Project Management Institute, 2017), analizando las causas y formulando acciones correctivas.INTRODUCCIÓN 1. GENERALIDADES 2. MARCOS DE REFERENCIA 3. METODOLOGÍA 4. PRODUCTOS A ENTREGAR 5. RESULTADOS ESPERADOS E IMPACTO 6. RECOLECCIÓN DE INFORMACIÓN 7. DIAGNÓSTICO 8. GUÍA METODOLÓGICA PARA EL DESARROLLO DE LA OBRA A PARTIR DEL GRUPO DE PROCESOS DE MONITOREO Y CONTROL 9. CONCLUSIONES 10.BIBLIOGRAFÍAEspecializaciónEspecialista en Gerencia de Obras Civile

    Predicting 6-minute walking test outcomes in patients with chronic obstructive pulmonary disease without physical performance measures

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    Background and Objective: Chronic obstructive pulmonary disease (COPD) requires a multifactorial assessment, evaluating the airflow limitation and symptoms of the patients. The 6-min walk test (6MWT) is commonly used to evaluate the functional exercise capacity in these patients. This study aims to propose a novel predictive model of the major 6MWT outcomes for COPD assessment, without physical performance measurements. Methods: Cardiopulmonary and clinical parameters were obtained from fifty COPD patients. These parameters were used as inputs of a Bayesian network (BN), which integrated three multivariate models including the 6-min walking distance (6MWD), the maximum HR (HRmax ) after the walking, and the HR decay 3 min after (HRR3 ). The use of BN allows the assessment of the patients’ status by predicting the 6MWT outcomes, but also inferring disease severity parameters based on actual patient’s 6MWT outcomes. Results: Firstly, the correlation obtained between the estimated and actual 6MWT measures was strong (R = 0.84, MAPE = 8.10% for HRmax ) and moderate (R = 0.58, MAPE = 15.43% for 6MWD and R = 0.58, MAPE = 32.49% for HRR3 ), improving the classical methods to estimate 6MWD. Secondly, the classification of disease severity showed an accuracy of 78.3% using three severity groups, which increased up to 84.4% for two defined severity groups. Conclusions: We propose a powerful two-way assessment tool for COPD patients, capable of predicting 6MWT outcomes without the need for an actual walking exercise. This model-based tool opens the way to implement a continuous monitoring system for COPD patients at home and to provide more personalized care
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