418 research outputs found

    Self-consistent model for ambipolar tunneling in quantum-well systems

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    We present a self-consistent approach to describe ambipolar tunneling in asymmetrical double quantum wells under steady-state excitation and extend the results to the case of tunneling from a near-surface quantum well to surface states. The results of the model compare very well with the behavior observed in photoluminescence experiments in InGaAs/InPInGaAs/InP asymmetric double quantum wells and in near-surface AlGaAs/GaAsAlGaAs/GaAs single quantum wells.Comment: 10 pages, REVTeX 3.

    We only die once... but from how many causes?

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    Analysing causes of death provides a betterunderstanding of long-term mortality trends. InFrance, the death certificates completed by physiciansgenerally mention several causes of death (2.4 onaverage in 2011). As a general rule, just one of them,the so-called underlying cause, is taken into account.As a result, the contribution of certain diseases-endocrine diseases for example-to mortality isseverely underestimated. In a context of rising lifeexpectancy where people increasingly die not from asingle cause of death but from several, it is importantto also take these contributing causes into account

    Salmon bias effect as hypothesis of the lower mortality rates among immigrants in Italy

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    Compared with natives, immigrants have lower all-cause mortality rates, despite their lower socioeconomic status, an epidemiological paradox generally explained by the healthy migrant effect. Another hypothesis is the so-called salmon bias effect: “statistically immortal” subjects return to their country of origin when they expect to die shortly, but their deaths are not registered in the statistics of the country of residence. This underestimation of deaths determines an artificially low immigrant mortality rate. We aimed to estimate the potential salmon bias effect on differences in mortality rates between Italians and immigrants. We used a national cohort of all Italians registered in the 2011 census and followed up for mortality from 2012 to 2016. Mortality data were retrieved from the Causes of Death Register, which included all deaths occurring in the country and the Resident Population Register, which collects also the deaths occurring abroad. We assumed as a possible salmon bias event the death of an immigrant resident in Italy that died in his/her country of origin. Considering the deaths occurring in the country of origin, we observed an 18.1% increase in the overall mortality rates for immigrants and an increase of 23.7% in the age-standardized mortality rate. Mortality rates of immigrants resident in Italy, calculated without taking into account the deaths occurring in the country of origin, are certainly underestimated. However, the salmon bias only partly explains the difference in mortality rates between immigrants and Italians

    Looking at Localized Excitons in Quantum Structures: A Theoretical Description

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    We present a theory of scanning local optical spectroscopy in quantum structures taking into account structural disorder. The calculated spatially resolved spectra show the individual spectral lines from the exciton states localized by the disordered potential as well as the quasicontinua spectra at positions close to the potential barriers in agreement with the experimental findings

    Perioperative and periprocedural airway management and respiratory safety for the obese patient: 2016 SIAARTI Consensus

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    Proper management of obese patients requires a team vision and appropriate behaviors by all health care providers in hospital. Specialist competencies are fundamental, as are specific clinical pathways and good clinical practices designed to deal with patients whose Body Mass Index (BMI) is ≥30 kg/m2. Standards of care for bariatric and non-bariatric surgery and for the critical care management of this population exist but are not well defined nor clearly followed in every hospital. Thus every anesthesiologist is likely to deal with this challenging population. Obesity is a multisystem, chronic, proinflammatory disorder. Unfortunately many countries are facing a marked increase in the obese population, defined as "globesity". Obesity presents an added risk in hospital, leading health care organizations to call for action to avoid adverse events and preventable complications. Periprocedural assessment and critical care strategies designed specifically for obese patients are crucial for reducing morbidity and mortality during surgery and in emergency settings, critical care and other particular settings (e.g., obstetrics). Specific care is needed for airway management, as are proactive strategies to reduce the risk of cardiovascular, endocrine, metabolic and infective complications; any effort can be fruitful, including special attention to the science of human factors. The Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care (SIAARTI) organized a consensus project involving other national scientific societies to increase risk awareness, define the best multidisciplinary approach for treating obese patients in election and emergency, and enable every hospital to provide appropriate levels of care and good clinical practices. The Obesity Project Task Force, a section of the SIAARTI Airway Management Study Group, used a formal consensus process to identify a series of notes, alerts and statements, to be adopted as bundles, to define appropriate clinical pathways for hospitalized obese patients. The consensus, approved by the Task Force and endorsed by several European scientific societies actively operating in this field, is presented herein
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