417 research outputs found

    Combined electrical transport and capacitance spectroscopy of a MoS2LiNbO3{\mathrm{MoS_2-LiNbO_3}} field effect transistor

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    We have measured both the current-voltage (ISDI_\mathrm{SD}-VGSV_\mathrm{GS}) and capacitance-voltage (CC-VGSV_\mathrm{GS}) characteristics of a MoS2LiNbO3\mathrm{MoS_2-LiNbO_3} field effect transistor. From the measured capacitance we calculate the electron surface density and show that its gate voltage dependence follows the theoretical prediction resulting from the two-dimensional free electron model. This model allows us to fit the measured ISDI_\mathrm{SD}-VGSV_\mathrm{GS} characteristics over the \emph{entire range} of VGSV_\mathrm{GS}. Combining this experimental result with the measured current-voltage characteristics, we determine the field effect mobility as a function of gate voltage. We show that for our device this improved combined approach yields significantly smaller values (more than a factor of 4) of the electron mobility than the conventional analysis of the current-voltage characteristics only.Comment: to appear in Applied Physics Letter

    Polarization-Sensitive Photodetectors Based on Directionally Oriented Organic Bulk-Heterojunctions

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    Polarized spectroscopic photodetection enables numerous applications in diverse areas such as sensing, industrial quality control, and visible light communications. Although organic photodetectors (OPDs) can offer a cost-effective alternative to silicon-based technology—particularly when flexibility and large-area arrays are desired—polarized OPDs are only beginning to receive due research interest. Instead of resorting to external polarization optics, this report presents polarized OPDs based on directionally oriented blends of poly(3-hexylthiophene) (P3HT) and benchmark polymer or nonfullerene acceptors fabricated using a versatile solution-based method. Furthermore, a novel postprocessing scheme based on backfilling and plasma etching is advanced to ameliorate high dark-currents that are otherwise inherent to fibrillar active layers. The resulting polarized P3HT:N2200 OPDs exhibit a broad enhancement across all principal figures of merit compared to reference isotropic devices, including peak responsivities of 70 mA W1^{-1} and up to a threefold increase in 3 dB bandwidth to 0.75 MHz under parallel-polarized illumination. Polarization ratios of up to 3.5 are obtained across a spectral range that is determined by the specific donor–acceptor combinations. Finally, as a proof-of-concept demonstration, polarized OPDs are used for photoelasticity analysis of rubber films under tensile deformation, highlighting their potential for existing and emerging applications in advanced optical sensing

    CAMBIOS EN LAS VARIABLES DE RIESGO CARDIOVASCULAR EN UNA COHORTE DE ESTUDIANTES UNIVERSITARIOS DE LA CIUDAD DE MÉXICO

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    Las enfermedades cardiovasculares ocupan actualmente los primeros lugares de mortalidad  y en países desarrollados y  de acuerdo a las tendencias actuales  lo serán también en los países en desarrollo. No se han realizado estudios de cohorte relacionados a conocer el comportamiento de las variables cardiovasculares en población de América Latina, por ello, el propósito del presente estudio fue determinar el comportamiento a tres años y medio de las variables de riesgo cardiovascular en estudiantes universitarios de la ciudad de México. (Universidad Autónoma Metropolitana-Iztapalapa).El diseño del  estudio fue  de cohorte prospectiva. Ingresaron 73 estudiantes, se autoaplicó un cuestionario para obtener información demográfica, de antecedentes patológicos heredofamiliares y factores de riesgo. Se medió, peso, talla, Índice de Masa Corporal (IMC), Circunferencia de Cintura (CC) % de grasa corporal y presión arterial. Se tomó muestra sanguínea en ayunas para medir colesterol total (CT), triglicéridos (Tg), Lípidos de Baja densidad (LDL) y de alta densidad (HDL)  y glucosa. Se calculó el Índice Aterogénico (IA). Resultados. El total de alumnos que terminaron el seguimiento fue de 50.  35 mujeres y 15 hombres.  El 70% de los estudiantes tenía antecedentes familiares de diabetes, 38% de hipertensión, 12% era fumador  y 58% ingería alcohol por lo menos una vez al mes. De acuerdo al IMC el 34% de las mujeres tenía sobrepeso y 5.7 eran obesas. Durante el periodo de seguimiento, los hombres incrementaron significativamente (0,00) el peso, la CC, y la glucosa. Las mujeres solo el LDL, la sístole y diástole disminuye de manera significativa ( 0.23, 0.18) respectivamente. Ningún estudiante fue diabético o hipertenso durante el periodo de estudio. Los hallazgos de este estudio no tienen relevancia clínica aún, sin embargo se debe enfatizar en la prevención primaria dentro de las universidades. Abstract Cardiovascular diseases are one of the main causes of death and disability in developed countries and it is currently increasing in developing countries too. Given that there are scarce cohort studies in -Latin America regarding cardiovascular risk factors, particularly in young population groups, the purpose of the this study was to follow up the behaviour of cardiovascular variables during a period of three and a half years. The study was conducted in a university student population ages 18 to 25 years old. Methodology.  A prospective cohort study of 73 university students from Mexico City was performed. A self-assessment questionnaire was used to obtain demographic characteristics and cardiovascular risk factors. Anthropometric, clinical, and biochemical variables were measured every three months. In addition, weight, height, Body Mass Index (BMI), waist circumference (WC), percentage body fat, and blood pressure were measured. From blood samples, cholesterol, triglycerides, High Density Lipoproteins and glucose were measured. Low Density Lipoproteins were calculated using the Friedewald formula. Paired Student’s t-tests were performed in order to compare means and cases  were expressed in graphical formats for lipid results. Results. Only 35 women and 15 men completed the three and a half years follow up. Of this total, 70% of students had diabetes background, 38% had hypertension, 12% had smoked and 58% had drank alcohol at least once a month. According to BMI measurements, 34% of women were overweight and 5.7% were obese compared with men where 27.7% were overweight. Men presented no cases of obesity. Conclusions. The behavior of cardiovascular variables over the three and a half- year period were different - between women and men. During this period, men increased significantly (0 .000) their weight, WC, BMI, and glucose levels.  Women, only LDL levels  increased significantly (0.18) while systole and diastole measures decrease significantly ( 0.23, 0.18). No subjects reported suffering from diabetes or hypertension during the period of study. The difference over the follow up did not have clinical relevance. Palabras clave: Variables cardiovasculares, cohorte, estudiantes universitarios

    Polarization-Sensitive Photodetectors Based on Directionally Oriented Organic Bulk-Heterojunctions

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    Polarized spectroscopic photodetection enables numerous applications in diverse areas such as sensing, industrial quality control, and visible light communications. Although organic photodetectors (OPDs) can offer a cost-effective alternative to silicon-based technology—particularly when flexibility and large-area arrays are desired—polarized OPDs are only beginning to receive due research interest. Instead of resorting to external polarization optics, this report presents polarized OPDs based on directionally oriented blends of poly(3-hexylthiophene) (P3HT) and benchmark polymer or nonfullerene acceptors fabricated using a versatile solution-based method. Furthermore, a novel postprocessing scheme based on backfilling and plasma etching is advanced to ameliorate high dark-currents that are otherwise inherent to fibrillar active layers. The resulting polarized P3HT:N2200 OPDs exhibit a broad enhancement across all principal figures of merit compared to reference isotropic devices, including peak responsivities of 70 mA W1^{-1} and up to a threefold increase in 3 dB bandwidth to 0.75 MHz under parallel-polarized illumination. Polarization ratios of up to 3.5 are obtained across a spectral range that is determined by the specific donor–acceptor combinations. Finally, as a proof-of-concept demonstration, polarized OPDs are used for photoelasticity analysis of rubber films under tensile deformation, highlighting their potential for existing and emerging applications in advanced optical sensing

    Epstein Barr virus in relation to apoptosis markers and patients' outcome in pediatric B-cell Non-Hodgkin lymphoma

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    In this study, we investigated Epstein Barr virus (EBV) presence, associated to proliferation and apoptosis proteins in pediatric B-cell Non-Hodgkin lymphoma (B-NHL). EBERs, Ki67, active caspase 3, Bax and Bcl2 were analyzed on B-NHL tissue from 40 patients. Forty percent showed EBV expression, significantly higher among patients ≤10. years (P= 0.027), and associated with immunosuppression (P= 0.020), but not associated apotosis markers. However, EBV was associated with a worse event-free survival (P= 0.016), particularly under immunosuppression. Even though EBV did not seem to alter apoptotic pathways, it exhibited survival disadvantage and could be an important cofactor in B-cell lymphomagenesis in younger children.Fil: Chabay, Paola Andrea. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lara, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Lorenzetti, Mario Alejandro. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cambra, P.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Acosta Haab, G.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Aversa, L.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: de Matteo, Elena Noemí. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Preciado, María Victoria. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Complicaciones de la colocación de malla sintética vaginal para la incontinencia urinaria de esfuerzo

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    ResumenAntecedentesLas mallas para la incontinencia urinaria (IU) se han utilizado a pesar de la falta de evidencia de nivel i en la literatura para evaluar su seguridad y eficacia a largo plazo. Las complicaciones relacionadas con la malla provocaron una advertencia emitida por la FDA en 2008 y dejaron de ser consideradas eventos raros. Las complicaciones más comunes son la retención aguda de orina, sangrado, recurrencia o persistencia de la IU, erosión de uretra e infección de la malla.ObjetivoConocer cuáles son las complicaciones derivadas del tratamiento quirúrgico de la IU femenina con la colocación de mallas suburetrales.Material y métodoSe analizaron los pacientes con diagnóstico de IU operadas con cirugía antiincontinencia y colocación de malla vaginal del año 2007 al 2014. Se analizó las complicaciones derivadas de la colocación de malla y la recuperación de continencia.ResultadosA 58 pacientes se les colocó sling (cabestrillo) con malla sintética; edad promedio de 56 años. El 51% de las pacientes tenían IU de esfuerzo y el 49% IU mixta. Las complicaciones tempranas fueron: 4 pacientes con retención aguda de orina. Las complicaciones tardías: dolor uretral o vaginal (12.2%), dispareunia (20%) y extrusión de malla (10%) manejado con retiro de la misma, 2 de ellas requiriendo 2 procedimientos quirúrgicos. El 12% presentaron urgencia de novo, el 90.2% evolucionaron sin incontinencia, el 9.7% con IU postoperatoria y 2 pacientes sin mejoría.DiscusiónNuestra serie, aunque pequeña, muestra una baja tasa de complicaciones a largo plazo relacionadas con la malla en comparación con la mayoría de las series que muestran una tasa de reoperación de hasta>70% y con múltiples casos de retiro de malla, por lo que en nuestra experiencia los slings suburetrales continúan siendo una opción adecuada en el manejo de la IU.ConclusionesLos slings suburetrales son una opción segura y efectiva en el manejo de la IU.AbstractBackgroundSurgical mesh has been used for treating urinary incontinence (UI) despite the lack of level i evidence in the literature evaluating its long-term safety and efficacy. Mesh-related complications were responsible for a warning issued by the FDA in 2008 and they stopped being considered rare events. The most common complications are acute urinary retention, bleeding, recurrence or persistence of UI, erosion of the urethra, and mesh infection.AimsTo determine the complications derived from surgical UI treatment with the placement of suburethral mesh in women.Material and methodPatients diagnosed with UI that underwent anti-incontinence surgery with the placement of vaginal mesh within the time frame of 2007 and 2014 were analyzed. Mesh placement complications and the recovery of continence were evaluated.ResultsA synthetic mesh sling was placed in 58 patients with a mean age of 56 years. A total of 51% of the patients had stress urinary incontinence and 49% had mixed urinary incontinence. Early complications were: 4 patients with acute urine retention. Late complications were: urethral or vaginal pain (12.2%), dyspareunia (20%), and mesh extrusion (10%) that was managed through mesh removal; 2 of those patients required surgical procedures. Twelve percent of the patients presented with de novo urgency, 90.2% progressed with no incontinence, 9.7% presented with postoperative UI, and 2 patients had no improvement.DiscussionAlthough small, our case series showed a low long-term complication rate with the use of surgical mesh, compared with the majority of case series that demonstrate a re-operation rate>70%, as well as numerous cases of mesh removal. Thus, it is our experience that suburethral slings continue to be an adequate UI management option.ConclusionsSuburethral slings are a safe and effective option in UI management

    "A little theatrical but mostly athletic": The mutable erotics of Miranda July's The First Bad Man

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    By attending to the inherent flux of sexual fantasy, Miranda July’s first novel The First Bad Man reveals a mobile and mutable erotics capable of generating an enlarged range of self-identification and relational intimacy, far from any essentialist assumptions of stable or coherent sexual identity. July focuses specifically upon role-play as the means to unpack the normative categories of hetero/homosexuality, masculinity and femininity, celebrating rather than pathologising qualities like superficiality and inconsistency. The novel touches upon many polarising issues (for example, sexual violence, sadomasochism and assisted reproductive technology), deftly avoiding the conventional language which colours perception. Both erotic and humorous, The First Bad Man helps to redefine the often highly charged discourse around sex and sexuality
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