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Search Results: 1 - 10 of 542219 matches for " M. C. Torrent "
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Synchronization in semiconductor laser rings
Javier M. Buldu,M. C. Torrent,Jordi Garcia-Ojalvo
Physics , 2006, DOI: 10.1109/JLT.2007.895555
Abstract: We examine the dynamics of semiconductor lasers coupled in a ring configuration. The lasers, which have stable output intensity when isolated, behave chaotically when coupled unidirectionally in a closed chain. In this way, we show that neither feedback nor bidirectional coupling is necessary to induce chaotic dynamics at the laser output. We study the synchronization phenomena arising in this particular coupling architecture, and discuss its possible application to chaos-based communications. Next, we extend the study to bidirectional coupling and propose an appropriate technique to optical chaos encryption/decryption in closed chains of mutually coupled semiconductor lasers.
Emergence of spike correlations in periodically forced excitable systems
Jose A. Reinoso,M. C. Torrent,Cristina Masoller
Physics , 2015,
Abstract: In sensory neurons the presence of noise can facilitate the detection of weak information-carrying signals, which are encoded and transmitted via correlated sequences of spikes. Here we investigate relative temporal order in spike sequences induced by a subthreshold periodic input, in the presence of white Gaussian noise. To simulate the spikes, we use the FitzHugh-Nagumo model, and to investigate the output sequence of inter-spike intervals (ISIs), we use the symbolic method of ordinal analysis. We find different types of relative temporal order, in the form of preferred ordinal patterns which depend on both, the strength of the noise and the period of the input signal. We also demonstrate a resonance-like behavior, as certain periods and noise levels enhance temporal ordering in the ISI sequence, maximizing the probability of the preferred patterns. Our findings could be relevant for understanding the mechanisms underlying temporal coding, by which single sensory neurons represent in spike sequences the information about weak periodic stimuli.
Coherence and synchronization in diode-laser arrays with delayed global coupling
J. Garcia-Ojalvo,J. Casademont,C. R. Mirasso,M. C. Torrent,J. M. Sancho
Physics , 1998, DOI: 10.1142/S021812749900167X
Abstract: The dynamics of a semiconductor-laser array whose individual elements are coupled in a global way through an external mirror is numerically analysed. A coherent in-phase solution is seen to be preferred by the system at intermediate values of the feedback coupling strength. At low values of this parameter, a strong amplification of the spontaneous emission noise is observed. A tendency towards chaos synchronization is also observed at large values of the feedback strength.
Effect of External Noise Correlation in Optical Coherence Resonance
J. M. Buldu,J. Garcia-Ojalvo,Claudio R. Mirasso,M. C. Torrent,J. M. Sancho
Physics , 2001, DOI: 10.1103/PhysRevE.64.051109
Abstract: Coherence resonance occurring in semiconductor lasers with optical feedback is studied via the Lang-Kobayashi model with external non-white noise in the pumping current. The temporal correlation and the amplitude of the noise have a highly relevant influence in the system, leading to an optimal coherent response for suitable values of both the noise amplitude and correlation time. This phenomenon is quantitatively characterized by means of several statistical measures.
Numerical and experimental study of the effects of noise on the permutation entropy
C. Quintero-Quiroz,Simone Pigolotti,M. C. Torrent,Cristina Masoller
Physics , 2015, DOI: 10.1088/1367-2630/17/9/093002
Abstract: We analyze the effects of noise on the permutation entropy of dynamical systems. We take as numerical examples the logistic map and the R\"ossler system. Upon varying the noise strengthfaster, we find a transition from an almost-deterministic regime, where the permutation entropy grows slower than linearly with the pattern dimension, to a noise-dominated regime, where the permutation entropy grows faster than linearly with the pattern dimension. We perform the same analysis on experimental time-series by considering the stochastic spiking output of a semiconductor laser with optical feedback. Because of the experimental conditions, the dynamics is found to be always in the noise-dominated regime. Nevertheless, the analysis allows to detect regularities of the underlying dynamics. By comparing the results of these three different examples, we discuss the possibility of determining from a time series whether the underlying dynamics is dominated by noise or not.
Dynamics of modal power distribution in a multimode semiconductor laser with optical feedback
J. M. Buldu,J. Trull,M. C. Torrent,J. Garcia-Ojalvo,Claudio R. Mirasso
Physics , 2001, DOI: 10.1088/1464-4266/4/1/101
Abstract: The dynamics of power distribution between longitudinal modes of a multimode semiconductor laser subjected to external optical feedback is experimentally analyzed in the low-frequency fluctuation regime. Power dropouts in the total light intensity are invariably accompanied by sudden activations of several longitudinal modes. These activations are seen not to be simultaneous to the dropouts, but to occur after them. The phenomenon is statistically analysed in a systematic way, and the corresponding delay is estimated.
Association between nutritional risk based on the NRS-2002 test and hospital morbidity and mortality Evaluación de la asociación entre el grado de riesgo nutricional según el test NRS-2002 y la morbimortalidad hospitalaria
G. Mercadal-Orfila,J. Lluch-Taltavull,C. Campillo-Artero,M. Torrent-Quetglas
Nutrición Hospitalaria , 2012, DOI: 10.3305/nh.2012.27.4.5791
Abstract: Objective: To analyse the relationship between the presence of malnutrition (MN), as measured by the NRS-2002 nutritional evaluation, and the rate of morbidity and mortality. Design: Cross-sectional study. Setting: Patients admitted to Mateu Orfila Hospital, the regional hospital for the island of Menorca, Spain. Subjects: 1,075 patients who were admitted to Mateu Orfila Hospital (Menorca) who had laboratory studies and a nutritional risk (NR) evaluation available were studied. Those who had a clinical suspicion of MN or those at risk were studied. Intervention: Demographic (age, gender) and clinical (current weight, normal weight, body mass index, weight loss, oral intake, presence of intestinal failure, fistula, renal failure, respiratory infection, urinary infection, hyperglycaemia, admission to the ICU, hospital stay, days of parenteral nutrition treatment and reason for admission) were collected during hospitalisation, as well as hospital mortality and mortality at 6 months following discharge. All underwent the NRS-2002 test. Results: The mean patient age was 67.9 years and 58.3% were men. 62% of patients met the criteria for manutrition according to the NRS-2002 test. A statistically significant association was seen between malnutrition according to the NRS-2002 and intestinal failure, fistula, renal failure, respiratory infection, hyperglycemia, hospital mortality and mortality at 6 months. Conclusion: Malnutrition affects more than half of the patients who are admitted to a medium-long admission hospital and it is associated with increased morbidity and mortality. The results underscore the need to establish an update plan and preventative and therapeutic nutritional follow-up. These measures reduce the rate of avoidable complications and save the costs associated with them. Objetivo: Determinar la relación entre el grado de Desnutrición (DN), detectada según el test de valoración nutricional NRS-2002, y la tasa de morbimortalidad. Métodos: Estudio transversal de 1075 pacientes que ingresaron en el Hospital Mateu Orfila (Menorca) de los que se disponía una analítica de ingreso y valoración del riesgo nutricional (RN) mediante el test NRS-2002. Se recogieron datos demográficos (edad, sexo) y clínicos (peso actual, peso habitual, índice Masa Corporal, pérdida peso, ingesta oral, presencia de fracaso intestinal, fístula, fracaso renal, infección respiratoria, infección urinaria, hiperglucemia, estancia en la UCI, estancia hospitalaria, días de tratamiento de nutrición parenteral y enfermedad motivo de ingreso) durante su hospitalización así como l
Acción del veneno de Bothrops jararacussu de Argentina sobre la coagulación sanguínea Activity of the venom of Bothrops jararacussu of Argentina on blood coagulation
S.L. Maru?ak,R.M. Ruíz de Torrent,G.P. Teibler,C.C. Gay
InVet , 2006,
Abstract: La intoxicación por mordeduras de serpientes del género Bothrops (yarará) de Argentina se caracteriza por causar efectos locales y sistémicos. Entre los sistémicos pueden generar alteraciones en la coagulación de la sangre, hemorragias, shock, insuficiencia renal. En este trabajo se estudiaron los efectos que causa el veneno de Bothrops jararacussu de Misiones, Argentina, sobre la coagulación de la sangre. Se utilizaron métodos in vitro e in vivo para evaluar la actividad coagulante, fibrinolítica y defibrinante, como así también la capacidad de degradar el fibrinógeno y la letalidad del veneno. El veneno mostró ser α-fibrinogenolítico y los resultados para las actividades ensayadas fueron: concentración coagulante mínima (CCM) 18,5 μg/ml, concentración fibrinolítica mínima (CFM) 9,5 mg/ml, dosis defibrinante mínima (DDM) 1,56 μg, DL50 43,52 μg/ratón, los que difieren de los obtenidos para otras especies de Bothrops e incluso dentro de la misma especie, pero distribuídas en otras regiones sudamericanas. Se concluye que el veneno de B. jararacussu de Argentina afecta marcadamente el sistema hemostático, y que las actividades coagulantes y anticoagulantes exhibidas por esta secreción probablemente influyan en la letalidad del veneno, dado que contribuirían a la aparición de hemorragias que, de ser severas, conducen a fallo renal y muerte de la víctima. The envenomation by snakes of the genus Bothrops of Argentina causes local and systemic signs. Among the systemic damages, bothropic venoms induce a wide variety of effects on blood coagulation, haemorrhage, shock and renal failure. In this paper the effects of Bothrops jararacussu venom from Argentina on the hemostatic system were determined. In order to estimate blood-clotting, fibrinolytic and defibrinating activities of the venom, in vitro and in vivo tests were employed. The ability to degrade fibrinogen and the lethal dosis (DL50) also were determined. The B. jararacussu venom appears to be fibrinogenolytic and the values obtained for assayed activities were minimum blood-clotting concentration 18,5 μg/ml, minimum fibrinolytic dose 9,5 mg/ml, minimum defibrinating dose 1,56 μg, LD50 43,52 μg/mouse. These results differ from those obtained for other species of genus Bothrops, or from the same species that inhabits in different South American regions. It is concluded that Bothrops jararacussu venom from Argentina largely affects blood coagulation system, and that the procoagulant and anticoagulant activities exhibited by this secretion may contribute to the lethality of the venom, since they could promo
Zero-lag long-range synchronization via dynamical relaying
Ingo Fischer,Raul Vicente,Javier M. Buldu,Michael Peil,Claudio R. Mirasso,M. C. Torrent,Jordi Garcia-Ojalvo
Physics , 2006, DOI: 10.1103/PhysRevLett.97.123902
Abstract: We show that simultaneous synchronization between two delay-coupled oscillators can be achieved by relaying the dynamics via a third mediating element, which surprisingly lags behind the synchronized outer elements. The zero-lag synchronization thus obtained is robust over a considerable parameter range. We substantiate our claims with experimental and numerical evidence of these synchronization solutions in a chain of three coupled semiconductor lasers with long inter-element coupling delays. The generality of the mechanism is validated in a neuronal model with the same coupling architecture. Thus, our results show that synchronized dynamical states can occur over long distances through relaying, without restriction by the amount of delay.
Gestión de la calidad en una unidad de cuidados intensivos: implementación de la norma ISO 9001:2008
Lorenzo Torrent,R.; Sánchez Palacios,M.; Santana Cabrera,L.; Cobian Martinez,J.L.; García del Rosario,C.;
Medicina Intensiva , 2010,
Abstract: the quality management systems make it possible to prioritize actions to maintain the safety and efficacy of health technologies. the intensive care unit of our hospital has implemented a quality management plan, which has obtained accreditation as "service certificate that manages its activities according to une-en iso 9001:2008" standard. with the application of quality management system, it has been possible to detect the needs that the service can cover in order to obtain the satisfaction of the patient, relative or health personnel of the other services of the hospital, to improve communications inside and outside of service, to secure greater understanding of the processes of the organization and control of risk, to delimit responsibilities clearly to all the personnel, to make better use of the time and resources and, finally, to improve the motivation of the personnel.
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