879 research outputs found

    Development and Applications of Aluminum Nitride Thin Film Technology

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    Aluminum nitride (AlN) thin films have aroused the interest of researchers due to their unique physicochemical properties. However, further studies on these semiconductor materials are still necessary to establish the manufacturing of high-performance devices for applications in various areas, such as telecommunications, microelectronics, and biomedicine. This chapter introduces AlN thin film technology that has made a wide range of applications possible. First, the main physicochemical properties of AlN, its wurtzite crystalline structure, and the incorporation of oxygen during the thin film deposition process are presented. Furthermore, the growth of AlN films by different techniques and their applications as a buffer layer and sensing layer are summarized. Special attention was given to the sputtering deposition process and the use of sputtered AlN films in SAW sensors

    Assessing Neuropsychological Performance in a Migrant Farm Working Colonia in Baja California, Mexico: A Feasibility Study

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    Neuropsychological impairments (NPI) can lead to difficulties in daily functioning and ultimately contribute to poor health outcomes. However, evidence for the feasibility of NPI assessment in resource-limited settings using tests developed in high literacy/high education cultures is sparse. The main objectives were to: (1) determine the feasibility and appropriateness of conducting neuropsychological assessments among a migrant farm worker population in Baja California, Mexico and (2) preliminary describe neuropsychological test performance in this unique population. A neuropsychological test battery was administered to 21 presumably healthy adults (8 men, 13 women) during a two-day international health services and research collaboration. All but one neuropsychological test (i.e. figure learning) was feasible and appropriate to administer to the study population. Contrary to expectations, participants performed better on verbal rather than nonverbal neuropsychological tests. Results support inclusion of neuropsychological tests into future studies among migrant farm worker populations in Baja California, Mexico

    Recurrent apparent life-threatening event as the first manifestation of congenital myasthenia

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    OBJECTIVE: To alert pediatricians about the importance of a careful investigation on recurrent apparent life-threatening events. Reports of the association of these events with congenital myasthenic syndromes were not found. CASE DESCRIPTION: A seven-month-old infant with recurrent apparent life-threatening events was admitted for investigation. During hospital stay, she presented cyanosis and respiratory failure, requiring mechanical ventilation for three days. After clinical improvement, hypotheses of gastroesophageal reflux and pulmonary aspiration were ruled out. The presence of eyelid ptosis, general hypotonia and weak crying led to the suspicion of congenital myasthenia, which was confirmed. Treatment with oral piridostigmine led to neurological and nutritional normalization, without any other apparent life-threatening event during the next three years. COMMENTS: The careful etiological investigation of apparent life-threatening events may lead to rare diagnosis that requires specific treatments, such as congenital myasthenia.OBJETIVO: Alertar os pediatras sobre a necessidade de investigar criteriosamente a etiologia de eventos com aparente risco de morte recorrente. Não foram encontrados relatos associando tais eventos à miastenia congênita. DESCRIÇÃO DO CASO: Lactente de sete meses apresentando história de eventos com aparente risco de morte recorrente foi internado para investigação. Durante a internação, apresentou cianose e dispneia progressiva, com necessidade de ventilação mecânica por três dias. Após a melhora clínica, e tendo sido descartadas as hipóteses de doença do refluxo gastroesofágico e aspiração pulmonar como desencadeantes, notou-se ptose palpebral bilateral, hipotonia apendicular e choro fraco, que conduziram à suspeita clínica de miastenia congênita. Após confirmação do diagnóstico, foi mantido tratamento ambulatorial com piridostigmina, com recuperação nutricional e neurológica, sem novos eventos com aparente risco de morte nos três anos seguintes. COMENTÁRIOS: A investigação minuciosa das causas de eventos com aparente risco de morte pode levar a diagnósticos menos frequentes que exigem tratamento específico, como a miastenia congênita.OBJETIVO: Alertar a los pediatras sobre la necesidad de investigar criteriosamente la etiología de eventos con aparente riesgo de muerte recurrente. No se encontraron relatos asociando tales eventos a la miastenia congénita. DESCRIPCIÓN DEL CASO: Lactante de siete meses presentando historia de eventos con aparente riesgo de muerte recurrente fue internado para investigación. Durante la internación, presentó cianosis y disnea progresiva, con necesidad de ventilación mecánica por tres días. Después de la mejora clínica, y habiendo sido rechazadas las hipótesis de enfermedad del reflujo gastroesofágico y aspiración pulmonar como desencadenantes, se notó ptosis palpebral bilateral, hipotonía apendicular y lloro débil, que condujeron a la sospecha clínica de miastenia congénita. Después de la confirmación del diagnóstico, se mantuvo el tratamiento ambulatorial con piridostigmina, con recuperación nutricional y neurológica, sin nuevos eventos con aparente riesgo de muerte en los tres años siguientes. COMENTARIOS: La investigación minuciosa de las causas de eventos con aparente riesgo de muerte puede llevar a diagnósticos menos frecuentes que exigen tratamiento específico, como la miastenia congénita.12112

    Pediatric emergency room: experience at a university hospital

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    OBJECTIVE: Describe the clinical course of pediatric patients treated at a pediatric emergency room in a university hospital. METHODS: This retrospective descriptive study was conducted between January 1st and December 31st, 2004. Data retrieved were: demographical and clinical characacteristics, diagnostic hypotheses, need of tracheal intubation, deaths, transfers and need of hospitalization of children between zero and 14 years old. Patients were divided in four groups: no deaths; deaths <24 hours; deaths >24 hours; transfers to other hospitals after initial care. RESULTS: 203 children were treated: 59.1% boys; mean age of 3.4 years; 65% previously healthy. The most common diagnosis was respiratory failure (31.1%). Of the 22 deaths, 3.5% took place during the first 24 hours and 7.4% after this; 172 children (84.7%) were discharged after a mean hospital length of stay of 19.2 days. Nine children (4.4%) were transferred to other hospitals. Among the 203 children, 50 children (24.6%) were intubated after admission and 86 children (42.4%) had to be admitted to a pediatric intensive care unit. CONCLUSIONS: The patients who died early were younger and mainly shock victims. Girls who suffered from previous diseases and respiratory failure were predominant among the patients who died 24 hours after initial care. Patients who survived the emergency crisis were mainly males, older and also presented respiratory diseases. The need for invasive procedures (tracheal intubation) and hospitalization in intensive care units was significant in this population, underscoring the need for adequate equipment and specialized professionals in the emergency pediatric hospital services.OBJETIVO: Descrever a casuística de pacientes pediátricos atendidos em sala de emergência pediátrica de um hospital universitário. MÉTODOS: Estudo retrospectivo descritivo de 1º de janeiro até 31 de dezembro de 2004, com crianças de zero a 14 anos, avaliadas quanto a dados epidemiológicos, hipótese diagnóstica, intubação orotraqueal, óbito, destino e duração da internação. Os pacientes foram divididos em quatro grupos: Não Óbitos; Óbitos <24 horas, Óbitos >24 horas e transferidos para outros hospitais. RESULTADOS: Foram atendidas 203 crianças; 59,1% meninos; média de idade 3,4 anos; 65% previamente hígidos. O diagnóstico mais freqüente foi insuficiência respiratória (31,1%). Dentre os 22 óbitos, 3,5% ocorreram nas primeiras 24 horas e 7,4% após estas primeiras 24 horas; 172 crianças (84,7%) evoluíram para alta após período médio de internação de 19,2 dias. Nove (4,4%) foram transferidas para outros hospitais. Das 203 crianças atendidas, 50 (24,6%) foram intubadas à admissão e 86 (42,4%) necessitaram internação em unidade de terapia intensiva pediátrica. CONCLUSÕES: Os pacientes que evoluíram para óbito precoce eram mais jovens e com diagnóstico de choque. Nos pacientes que evoluíram para óbito após 24 horas do atendimento inicial, predominaram meninas, com doenças prévias e insuficiência respiratória. Aqueles que sobreviveram ao atendimento de emergência eram, em maior freqüência, meninos mais velhos e com doenças respiratórias. Houve necessidade significativa de procedimento invasivo (intubação orotraqueal) e internação subseqüente em unidade de terapia intensiva, o que reforça a necessidade de equipamentos adequados e profissionais especializados no setor.15616

    Development and validation of HERWIG 7 tunes from CMS underlying-event measurements

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    This paper presents new sets of parameters (“tunes”) for the underlying-event model of the HERWIG7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in HERWIG7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at s=0.9, 7, and 13Te. The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the dat

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV
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