A simple spectral condition implying separability for states of bipartite quantum systems

For two qubits and for general bipartite quantum systems, we give a simple spectral condition in terms of the ordered eigenvalues of the density matrix which guarantees that the corresponding state is separable.Comment: 5 pages Revised 31 May 200

Depressive and anxiety symptoms screening in cardiac inpatients : a virtuous italian approach to psychocardiology

Despite the fact that American Heart Association (AHA) recommended a systematic screening for depression in cardiovascular inpatients, poor attention has been given to this issue. Furthermore, no specific guidelines exist for anxiety screening in cardiovascular inpatients. Thus, the aims of this study were to verify the feasibility of a depressive and anxiety symptoms screening protocol in an Italian hospital specializing in cardiovascular diseases and to evaluate both anxiety and depressive symptoms prevalence. A group of 2009 consecutive inpatients completed the 9-item Patient Health Questionnaire (PHQ-9) and the 7-item Generalized Anxiety Disorder (GAD-7). The rates of depressive and anxiety symptoms were almost 9% and 16% respectively. Men were less likely than women to experience both depressive and anxiety symptoms. Patients who were admitted to the heart failure unit reported higher risk of experiencing both symptoms compared to patients in other wards. Similarly, patients admitted to the cardiac surgery unit showed a higher risk of experiencing anxiety symptoms compared to other patients. The proposed screening procedure showed a good feasibility and acceptance. This study highlighted the importance of implementing a short screening procedure in hospitals dealing with cardiovascular inpatients to identify those individuals who require specific attention and interventions

Symmetry implies independence

Given a quantum system consisting of many parts, we show that symmetry of the system's state, i.e., invariance under swappings of the subsystems, implies that almost all of its parts are virtually identical and independent of each other. This result generalises de Finetti's classical representation theorem for infinitely exchangeable sequences of random variables as well as its quantum-mechanical analogue. It has applications in various areas of physics as well as information theory and cryptography. For example, in experimental physics, one typically collects data by running a certain experiment many times, assuming that the individual runs are mutually independent. Our result can be used to justify this assumption.Comment: LaTeX, contains 4 figure

One-and-a-half quantum de Finetti theorems

We prove a new kind of quantum de Finetti theorem for representations of the unitary group U(d). Consider a pure state that lies in the irreducible representation U_{mu+nu} for Young diagrams mu and nu. U_{mu+nu} is contained in the tensor product of U_mu and U_nu; let xi be the state obtained by tracing out U_nu. We show that xi is close to a convex combination of states Uv, where U is in U(d) and v is the highest weight vector in U_mu. When U_{mu+nu} is the symmetric representation, this yields the conventional quantum de Finetti theorem for symmetric states, and our method of proof gives near-optimal bounds for the approximation of xi by a convex combination of product states. For the class of symmetric Werner states, we give a second de Finetti-style theorem (our 'half' theorem); the de Finetti-approximation in this case takes a particularly simple form, involving only product states with a fixed spectrum. Our proof uses purely group theoretic methods, and makes a link with the shifted Schur functions. It also provides some useful examples, and gives some insight into the structure of the set of convex combinations of product states.Comment: 14 pages, 3 figures, v4: minor additions (including figures), published versio

Continuity and Stability of Partial Entropic Sums

Extensions of Fannes' inequality with partial sums of the Tsallis entropy are obtained for both the classical and quantum cases. The definition of kth partial sum under the prescribed order of terms is given. Basic properties of introduced entropic measures and some applications are discussed. The derived estimates provide a complete characterization of the continuity and stability properties in the refined scale. The results are also reformulated in terms of Uhlmann's partial fidelities.Comment: 9 pages, no figures. Some explanatory and technical improvements are made. The bibliography is extended. Detected errors and typos are correcte

Monogamy of entanglement and other correlations

It has been observed by numerous authors that a quantum system being entangled with another one limits its possible entanglement with a third system: this has been dubbed the "monogamous nature of entanglement". In this paper we present a simple identity which captures the trade-off between entanglement and classical correlation, which can be used to derive rigorous monogamy relations. We also prove various other trade-offs of a monogamy nature for other entanglement measures and secret and total correlation measures.Comment: 7 pages, revtex

Proyecto IRESUD: interconexión de sistemas fotovoltaicos a la red eléctrica en ambientes urbanos. estado de avance a julio de 2014 y primeras mediciones en sistemas piloto

En el marco de una convocatoria del Ministerio de Ciencia, Tecnología e Innovación Productiva, se conformó, en el año 2011, el consorcio público-privado IRESUD entre la Comisión Nacional de Energía Atómica (CNEA), la Universidad Nacional de San Martín (UNSAM) y 5 empresas privadas, para la ejecución del proyecto “Interconexión de Sistemas Fotovoltaicos a la Red Eléctrica en Ambientes Urbanos”. El principal objetivo del mismo es introducir en el país tecnologías asociadas con la interconexión a la red eléctrica, en áreas urbanas, de sistemas fotovoltaicos (FV), contemplando para ello cuestiones técnicas, económicas y regulatorias. En este trabajo, se presenta el grado de avance del proyecto en lo referente a las cuestiones regulatorias y a las instalaciones piloto realizadas o en ejecución en diferentes partes del país. Asimismo, se muestran las primeras mediciones de algunas de las instalaciones actualmente en operación y se analiza el comportamiento de un inversor FV de conexión a red.Fil: Durán, J. C.. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Socolovsky, Hernan Pablo. Comisión Nacional de Energía Atómica; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Raggio, D.. Comisión Nacional de Energía Atómica; ArgentinaFil: Godfrin, Elena María. Comisión Nacional de Energía Atómica; ArgentinaFil: Jakimczyk, J.. Universidad Tecnológica Nacional; ArgentinaFil: Martinez Bogado, Mónica Gladys. Universidad Nacional de San Martín; Argentina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Diaz, F. J.. Universidad Nacional de La Plata. Facultad de Informática; ArgentinaFil: Castro, N. E.. Universidad Nacional de La Plata. Facultad de Informática; ArgentinaFil: Pedro, G.. Provincia del Neuquen. Ministerio de Hacienda Obras y Servivcios Publicos. Ente Provincial de Energia del Neuquen; ArgentinaFil: Sepúlveda, O.. Provincia del Neuquen. Ministerio de Hacienda Obras y Servivcios Publicos. Ente Provincial de Energia del Neuquen; ArgentinaFil: Argañaraz, C.. Provincia del Neuquen. Ministerio de Hacienda Obras y Servivcios Publicos. Ente Provincial de Energia del Neuquen; ArgentinaFil: Benítez, E.. Universidad Nacional de Luján; ArgentinaFil: Roldán, A.. Universidad Nacional de Luján; ArgentinaFil: Righini, R.. Universidad Nacional de Luján; Argentin

Impact of Subsyndromal Delirium Occurrence and Its Trajectory during ICU Stay

Funding Information: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Publisher Copyright: © 2022 by the authors.Despite recent advances in the field, the association between subsyndromal delirium (SSD) in the ICU and poor outcomes is not entirely clear. We performed a retrospective multicentric observational study analyzing mental status during the first 72 h of ICU stay. Of the 681 patients included, SSD occurred in 22.7%. Considering the worst cognitive assessment during the first 72 h, 233 (34%) patients had normal mental status, 124 (18%) patients had SSD and 324 (48%) patients had delirium or coma. SSD was not independently associated with an increased risk of death when compared with normal mental status (OR 95%IC 1.0 vs. 1.35 [0.73–1.49], p = 0.340), but was associated with a longer ICU LOS (7.0 (4–12) vs. 4 (3–8) days, p 23 points. Our findings support the association of SSD with increased ICU LOS, but not with ICU mortality. Monitoring the trajectory of SSD early at ICU admission can help to identify patients with increased risk of conversion from SSD to delirium or coma.publishersversionpublishe

Evaluación de la calidad de la energía en dos casos de estudio: distorsión armónica inyectada por un sistema fotovoltaico de 40 kW y emitida por las cargas de una vivienda unifamiliar

Los posibles efectos de la conexión de sistemas foto voltaicos (FV) a la red eléctrica sobre la calidad del servicio, en particular en lo referente a la inyección de componentes armónicas, suelen ser una preocupación de las empresas distribuidoras y los entes de regulación. A fin de aportar datos cuantitativos en relación con este tema, se analizó la calidad de la energía: (i) en el punto de conexión de un sistema FV de 40 kW instalado en el Polo Científico y Tecnológico, y (ii) en uno de los circuitos eléctricos de una vivienda unifamiliar. Por un lado, las mediciones realizadas en el sistema FV permitieron verificar que las componentes armónicas de corriente inyectadas a la red están claramente por debajo de los límites establecidos por la norma IEC 61000-3-2. Por su parte, las mediciones efectuadas en la vivienda muestran que las componentes armónicas de corriente emitidas por electrodomésticos son significativamente mayores que las armónicas inyectadas por un inversor FV de potencia típica para una vivienda unifamiliar. Los análisis realizados permiten afirmar, en consecuencia, que la conexión de sistemas FV a la red eléctrica no afecta la calidad del servicio en cuanto a la distorsión armónica.The possible effects of the connection of photovoltaic (PV) systems to the power grid on service quality, particularly in relation to the injection of harmonic components, are often a concern of distribution companies and regulatory authorities. In order to provide quantitative data on this subject, the power quality was analyzed: (i) in the connection point of a 40 kW PV system installed in the Scientific and Technological Pole, and (ii) in one of the electrical circuits of a house. On one hand, measurements made in the 40 kW PV system allowed to verify that the current harmonic components injected into the network are clearly below the limits set by IEC 61000-3-2. Meanwhile, measurements performed in the electrical circuit of the house show that current harmonic components emitted by household appliances are significantly higher than the harmonics injected by a typical PV power inverter for a house. Therefore, the results presented in this paper support the conclusion that grid-connected PV systems do not affect the power quality in terms of harmonic distortion.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES