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1.
Nanotechnology ; 30(24): 244003, 2019 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-30790770

RESUMEN

We have designed, fabricated and tested a robust superconducting ratchet device based on topologically frustrated spin ice nanomagnets. The device is made of a magnetic Co honeycomb array embedded in a superconducting Nb film. This device is based on three simple mechanisms: (i) the topology of the Co honeycomb array frustrates in-plane magnetic configurations in the array yielding a distribution of magnetic charges which can be ordered or disordered with in-plane magnetic fields, following spin ice rules; (ii) the local vertex magnetization, which consists of a magnetic half vortex with two charged magnetic Néel walls; (iii) the interaction between superconducting vortices and the asymmetric potentials provided by the Néel walls. The combination of these elements leads to a superconducting ratchet effect. Thus, superconducting vortices driven by alternating forces and moving on magnetic half vortices generate a unidirectional net vortex flow. This ratchet effect is independent of the distribution of magnetic charges in the array.

2.
Rev Neurol ; 73(11): 373-382, 2021 Dec 01.
Artículo en Español, Inglés | MEDLINE | ID: mdl-34826330

RESUMEN

INTRODUCTION: Risk minimisation measures for valproate were implemented in Spain in 2015. OBJECTIVE: The objective of this study is to assess the effectiveness of valproate risk minimisation measures in Spain intended to decrease the use of valproate as a first-line therapy, and to evaluate the prescribing patterns of valproate in women, including women of childbearing potential, in the pre- and post-implementation risk minimisation measures periods. MATERIALS AND METHODS: The prescribing patterns of valproate in females and women of childbearing potential before and after risk minimisation measures implementation were examined using the longitudinal patient data database, which includes patient information from two panels: primary care physicians and neurologists/psychiatrists. Primary endpoint was the proportion of initial valproate prescriptions with at least one medication related to the valproate indications before the valproate initiation date. RESULTS: The proportion of incident valproate prescriptions with previous use of medication related to valproate indications was 78.0% (95% CI, 73.9%; 81.5%), and 78.2% (74.5%; 81.4%) in the main pre-and post-implementation periods in the primary care physician panel. The corresponding figures for women of childbearing potential were 79.6% (73.6%; 84.5%) and 75.5% (69.7%; 80.6%), respectively. The incidence rate of pregnancies exposed to valproate (per 1,000 person-years) in women of childbearing potential decreased from 17.4 the entire pre-implementation to 8.5 in the entire post-implementation periods. CONCLUSION: After the implementation of risk minimisation measures for valproate in Spain, no meaningful change in prescribing was observed regarding the proportion of valproate initiations preceded by prior medication related to valproate indications. The preventative measures recommended for use of valproate in women of childbearing potential should be considered.


TITLE: Eficacia de las medidas de minimización de riesgos del ácido valproico: estudio de utilización del fármaco en Europa, análisis de datos de España.Introducción. En 2015 se aplicaron en España distintas medidas para la minimización de los riesgos (MMR) del ácido valproico. Objetivo. El objetivo de este estudio es evaluar la eficacia de las MMR del ácido valproico en España, con el fin de reducir el uso de ácido valproico como terapia de primera línea y evaluar los patrones de prescripción de ácido valproico en las mujeres, incluidas las mujeres en edad fértil (MEF), en los períodos previos y posteriores a la implementación de las MMR. Materiales y métodos. Los patrones de prescripción del ácido valproico en mujeres y MEF antes y después de la implementación de las MMR se examinaron utilizando la base de datos longitudinales de pacientes (longitudinal patient data, LPD por sus siglas en inglés), que incluye información de pacientes de dos paneles: médicos de atención primaria (MAP) y neurólogos/psiquiatras. El criterio principal de valoración fue la proporción de prescripciones iniciales de ácido valproico con al menos un medicamento relacionado con indicaciones de ácido valproico antes de la fecha de inicio del ácido valproico. Resultados. La proporción de prescripciones de ácido valproico secundarias con uso previo de medicamentos relacionados con indicaciones de ácido valproico fue del 78% ­intervalo de confianza (IC) al 95%: 73,9-81,5%­ y del 78,2% (IC al 95%: 74,5-81,4%) en los períodos principales previo y posterior a la implementación en el panel de MAP. Las cifras correspondientes a MEF fueron del 79,6% (IC al 95%: 73,6-84,5%) y del 75,5% (IC al 95%: 69,7-80,6%), respectivamente. La tasa de incidencia de embarazos expuestos al ácido valproico (por 1.000 personas-años) en MEF disminuyó de 17,4 en el período completo previo a la implementación a 8,5 en el período completo posterior a la implementación. Conclusión. Tras la implementación de las MMR del ácido valproico en España no se observó ningún cambio significativo en las prescripciones respecto a la proporción de iniciaciones de ácido valproico precedidas por medicación previa relacionada con indicaciones de ácido valproico. Se deben tener en cuenta las medidas preventivas recomendadas para el uso de ácido valproico en MEF.


Asunto(s)
Anticonvulsivantes/uso terapéutico , Ácido Valproico/uso terapéutico , Adulto , Anciano , Anticonvulsivantes/efectos adversos , Estudios de Cohortes , Utilización de Medicamentos , Europa (Continente) , Femenino , Humanos , Persona de Mediana Edad , Riesgo , España , Ácido Valproico/efectos adversos
3.
Opt Express ; 18(12): 13301-8, 2010 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-20588459

RESUMEN

We study the optical emission of single semiconductor quantum dots weakly coupled to a photonic-crystal micro-cavity. The linearly polarized emission of a selected quantum dot changes continuously its polarization angle, from nearly perpendicular to the cavity mode polarization at large detuning, to parallel at zero detuning, and reversing sign for negative detuning. The linear polarization rotation is qualitatively interpreted in terms of the detuning dependent mixing of the quantum dot and cavity states. The present result is relevant to achieve continuous control of the linear polarization in single photon emitters.

6.
Nanoscale ; 11(23): 11152-11158, 2019 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-31144696

RESUMEN

Mechanically exfoliated van der Waals materials can be used to prepare proof-of-concept electronic devices. Their optoelectronic properties strongly depend on the geometry and number of layers present in the exfoliated flake. Once the device fabrication steps have been completed, tuning the device response is complex, since the geometry and number of layers cannot be easily modified. In this work, we employ Pulsed Focused Electron Beam Induced Etching (PFEBIE) to tailor the geometry and electronic properties of field effect transistors based on mechanically exfoliated Molybdenum Disulfide (MoS2) flakes. First, MoS2 field effect transistors are fabricated via optical lithography and conventional methods. Then, the geometry of the MoS2 source-drain conduction channel is modified employing a Xenon difluoride (XeF2) gas injection nozzle combined with a pulsed electron beam pattern-generation system. Electrical characterization of devices carried out before and after the nanopatterning step via PFEBIE reveals a shift in the doping from N-type towards P-type. We attribute this change to sulfur vacancies induced during the direct nanopatterning step. This is confirmed by micro-Raman and micro-Photoluminescence spectroscopy experiments. The direct nanopatterning method allows us to fine-tune the geometry and thus the electronic properties of the devices, once the conventional fabrication steps have been completed. The success rate of our tailoring method exceeds 85% when tuning the geometry of the flake into a 250 nm wide and straight conduction channel between source and drain.

7.
ACS Appl Mater Interfaces ; 10(9): 8190-8196, 2018 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-29461040

RESUMEN

Controlling graphene's doping will be critically important for its incorporation into future electronic and optoelectronic devices. Noncovalent functionalization through adsorption of organic molecules on graphene's surface has proved to be a promising route for achieving p- or n-type doping. However, due to the poor adhesion of the molecules, these tend to desorb over time under standard environmental conditions or in the presence of certain solvents. The resulting reversal in the achieved chemical doping is a major obstacle to using organic molecules as noncovalent graphene dopants. In this work, we present a simple method for achieving long-term p- and n-doping of graphene devices through vapor phase evaporation of organic molecules, followed by encapsulation under an inert Al2O3 film. This film, grown via an optimized atomic layer deposition process, ensures long-term doping stability, as confirmed by electrical transport and Raman spectroscopy measurements. The doping is maintained even after storing the devices for six weeks in ambient conditions and immersing them in a dopant removing solvent, demonstrating that the film is as an effective barrier against environmental degradation of the doped devices.

8.
Sci Rep ; 8(1): 12374, 2018 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-30120346

RESUMEN

We have studied two nanomagnet systems with strong (Co/Pd multilayers) and weak (NdCo alloy films) stray magnetic fields by probing the out-of-plane magnetic states with superconducting vortices. The hybrid samples are made of array of nanomagnets embedded in superconducting Nb thin films. The vortex motion detects relevant magnetic state features, since superconducting vortices are able to discriminate between different magnetic stray field strengths and directions. The usual matching effect between the superconducting vortex lattice and the periodic pinning array can be quenched by means of disorder magnetic potentials with strong stray fields at random. Ordered stray fields retrieve the matching effect and yield asymmetry and shift in the vortex dissipation signal. Furthermore vortices can discriminate the sizes of the nanomagnet magnetic domains, detecting magnetic domain sizes as small as 70 nm. In addition, we observe that the vortex cores play the crucial role instead of the supercurrents around the vortex.

9.
Rev. neurol. (Ed. impr.) ; 73(11): 373-382, Dic 1, 2021. ilus, tab, graf
Artículo en Inglés, Español | IBECS (España) | ID: ibc-229603

RESUMEN

Introducción: En 2015 se aplicaron en España distintas medidas para la minimización de los riesgos (MMR) del ácido valproico. Objetivo: El objetivo de este estudio es evaluar la eficacia de las MMR del ácido valproico en España, con el fin de reducir el uso de ácido valproico como terapia de primera línea y evaluar los patrones de prescripción de ácido valproico en las mujeres, incluidas las mujeres en edad fértil (MEF), en los períodos previos y posteriores a la implementación de las MMR. Materiales y métodos: Los patrones de prescripción del ácido valproico en mujeres y MEF antes y después de la implementación de las MMR se examinaron utilizando la base de datos longitudinales de pacientes (longitudinal patient data, LPD por sus siglas en inglés), que incluye información de pacientes de dos paneles: médicos de atención primaria (MAP) y neurólogos/psiquiatras. El criterio principal de valoración fue la proporción de prescripciones iniciales de ácido valproico con al menos un medicamento relacionado con indicaciones de ácido valproico antes de la fecha de inicio del ácido valproico. Resultados: La proporción de prescripciones de ácido valproico secundarias con uso previo de medicamentos relacionados con indicaciones de ácido valproico fue del 78% –intervalo de confianza (IC) al 95%: 73,9-81,5%– y del 78,2% (IC al 95%: 74,5-81,4%) en los períodos principales previo y posterior a la implementación en el panel de MAP. Las cifras correspondientes a MEF fueron del 79,6% (IC al 95%: 73,6-84,5%) y del 75,5% (IC al 95%: 69,7-80,6%), respectivamente. La tasa de incidencia de embarazos expuestos al ácido valproico (por 1.000 personas-años) en MEF disminuyó de 17,4 en el período completo previo a la implementación a 8,5 en el período completo posterior a la implementación...(AU)


Introduction: Risk minimisation measures for valproate were implemented in Spain in 2015.Objective: The objective of this study is to assess the effectiveness of valproate risk minimisation measures in Spain intended to decrease the use of valproate as a first-line therapy, and to evaluate the prescribing patterns of valproate in women, including women of childbearing potential, in the pre- and post-implementation risk minimisation measures periods. Materials and methods: The prescribing patterns of valproate in females and women of childbearing potential before and after risk minimisation measures implementation were examined using the longitudinal patient data database, which includes patient information from two panels: primary care physicians and neurologists/psychiatrists. Primary endpoint was the proportion of initial valproate prescriptions with at least one medication related to the valproate indications before the valproate initiation date. Results: The proportion of incident valproate prescriptions with previous use of medication related to valproate indications was 78.0% (95% CI, 73.9%; 81.5%), and 78.2% (74.5%; 81.4%) in the main pre-and post-implementation periods in the primary care physician panel. The corresponding figures for women of childbearing potential were 79.6% (73.6%; 84.5%) and 75.5% (69.7%; 80.6%), respectively. The incidence rate of pregnancies exposed to valproate (per 1,000 person-years) in women of childbearing potential decreased from 17.4 the entire pre-implementation to 8.5 in the entire post-implementation periods. Conclusion: After the implementation of risk minimisation measures for valproate in Spain, no meaningful change in prescribing was observed regarding the proportion of valproate initiations preceded by prior medication related to valproate indications. The preventative measures recommended for use of valproate in women of childbearing potential should be considered.(AU)


Asunto(s)
Humanos , Femenino , Adolescente , Adulto Joven , Adulto , Trastorno Bipolar/tratamiento farmacológico , Epilepsia/tratamiento farmacológico , Utilización de Medicamentos , Ácido Valproico/efectos adversos , Síndromes Epilépticos/tratamiento farmacológico , Prescripciones de Medicamentos , España , Neurología , Enfermedades del Sistema Nervioso , Neuropsiquiatría , Estudios de Cohortes , Reino Unido , Suecia , Alemania , Francia
10.
Leukemia ; 30(6): 1344-54, 2016 06.
Artículo en Inglés | MEDLINE | ID: mdl-26857467

RESUMEN

Pre-clinical studies have shown that injection of allogeneic T cells primed against a single minor histocompatibility antigen (MiHA) could cure hematologic cancers (HC) without causing any toxicity to the host. However, translation of this approach in humans has been hampered by the paucity of molecularly defined human MiHAs. Using a novel proteogenomic approach, we have analyzed cells from 13 volunteers and discovered a vast repertoire of MiHAs presented by the most common HLA haplotype in European Americans: HLA-A*02:01;B*44:03. Notably, out of >6000 MiHAs, we have identified a set of 39 MiHAs that share optimal features for immunotherapy of HCs. These 'optimal MiHAs' are coded by common alleles of genes that are preferentially expressed in hematopoietic cells. Bioinformatic modeling based on MiHA allelic frequencies showed that the 39 optimal MiHAs would enable MiHA-targeted immunotherapy of practically all HLA-A*02:01;B*44:03 patients. Further extension of this strategy to a few additional HLA haplotypes would allow treatment of almost all patients.


Asunto(s)
Neoplasias Hematológicas/terapia , Inmunoterapia/métodos , Antígenos de Histocompatibilidad Menor/uso terapéutico , Proteogenómica/métodos , Células Cultivadas , Femenino , Antígeno HLA-A2 , Antígeno HLA-B44 , Haplotipos , Humanos , Masculino
11.
Rev Epidemiol Sante Publique ; 53(2): 111-25, 2005 Apr.
Artículo en Francés | MEDLINE | ID: mdl-16012371

RESUMEN

BACKGROUND: The objective of this paper is the study of a health indicator allowing surveillance and evaluation of the overall health of the Paris population, and providing information to help prioritize possible choices among preventive and curative actions. Moreover, comparison between results obtained for Paris with a global health indicator, "Disability-adjusted life years" (DALYs) and available bibliographical data will enable clarifying some points about summary measures of health. METHODS: The method used is that of the Global Burden of Disease. It allows a ranking of diseases using an indicator called DALYs. This indicator integrates mortality and morbidity components by summing expected years of life lost due to premature mortality and calculated years of healthy life lost. DALYs were calculated using local mortality data and published regional disabilities tables from the World Health Organisation (WHO). RESULTS: There were a total of 242 061 DALYs for Paris for the year 1999. The six leading specific causes are: alcoholic psychosis and dependence (accounting for 6.5% of the total), lung cancers (5.7%), ischaemic hearth disease (4.8%), depression (4.4%), dementias (4.2%), and arthritis (3.9%). Men contributed the majority of DALYs for the first three. For four of the six leading causes, the majority of DALYs came from years lived with disability, rather than mortality. Only for lung cancer and ischaemic hearth disease was the majority of DALYs from years of life lost by mortality. CONCLUSION: The results for Paris are used to illustrate how DALYs can illuminate debates about public health priorities. Such data can inform the population about health condition and provide decision makers with global health indicators. The next step will be to estimate the DALYs from local morbidity data when available, and compare these results to those based on the World Health Organisation tables, which are not sensitive to local results other than those due to mortality. Future steps include further evaluation and development of this method for surveillance, assessment and evaluation of public health actions. However, some of the results obtained with this indicator underline the limits of this kind of analysis.


Asunto(s)
Enfermedad Crónica/epidemiología , Personas con Discapacidad/estadística & datos numéricos , Mortalidad , Salud Pública , Años de Vida Ajustados por Calidad de Vida , Adolescente , Adulto , Distribución por Edad , Anciano , Niño , Preescolar , Personas con Discapacidad/clasificación , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Trastornos Mentales/epidemiología , Persona de Mediana Edad , Paris/epidemiología , Distribución por Sexo
12.
Sci Rep ; 5: 15210, 2015 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-26469373

RESUMEN

We present a simple nanodevice that can operate in two modes: i) non-volatile three-state memory and ii) reading device. The nanodevice can retain three well defined states -1, 0 and +1 and can operate in a second mode as a sensor for external magnetic fields. The nanodevice is fabricated with an array of ordered triangular-shaped nanomagnets embedded in a superconducting thin film gown on Si substrates. The device runs based on the combination of superconducting vortex ratchet effect (superconducting film) with the out of plane magnetization (nanomagnets). The input signals are ac currents and the output signal are dc voltages. The memory mode is realized without applying a magnetic field and the nanomagnet stray magnetic fields govern the effect. In the sensor mode an external magnetic field is applied. The main characteristic of this mode is that the output signal is null for a precise value of the external magnetic field that only depends on the fabrication characteristics of the nanodevice.

13.
Dev Psychol ; 33(1): 120-34, 1997 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-9050397

RESUMEN

This study compared teaching and learning measures of 16 mother-child and sibling dyads playing a picture categorization game. Target children (mean age = 3 years 11 months) participated in 2 separate sessions, 1 with their mother and 1 with their older sibling (mean age = 6 years 11 months). Although siblings' teaching styles directed target children to make the correct choices, mothers provided information to help target children make choices on their own. Mothers labeled objects and categories more than siblings. Although target children scored higher with siblings than with mothers, this was because siblings categorized about half of the pictures themselves. Target children labeled objects and categories more with mothers than with siblings. These findings suggest important differences in how mothers and siblings interpreted the goals of the task, offering target children different teaching styles from which to learn.


Asunto(s)
Formación de Concepto , Desarrollo del Lenguaje , Relaciones Madre-Hijo , Semántica , Relaciones entre Hermanos , Conducta Verbal , Niño , Preescolar , Femenino , Humanos , Masculino , Conducta Materna , Aprendizaje Verbal , Vocabulario
14.
An Med Interna ; 8(9): 451-3, 1991 Sep.
Artículo en Español | MEDLINE | ID: mdl-1958782

RESUMEN

Two cases of patients with chronic eosinophilic pneumonia are presented. We highlight the possibility to obtain the diagnosis without lung biopsy, as well as the spectacular response to steroid treatment which has to be continued for a long period in order to avoid relapses.


Asunto(s)
Eosinofilia Pulmonar/diagnóstico , Adulto , Enfermedad Crónica , Humanos , Masculino , Persona de Mediana Edad , Prednisona/uso terapéutico , Eosinofilia Pulmonar/tratamiento farmacológico
15.
Biomed Pharmacother ; 65(8): 569-77, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21733656

RESUMEN

Among the problems associated to leishmaniasis, the two most outstanding ones are the lack of a vaccine and the adverse effects caused by drugs use for its control. Meglumine antimoniate compounds are the first-line drugs in the treatment for cutaneous leishmaniasis (the most prevalent form of the disease in Colombia); nevertheless, they are far from being ideal drugs due to their toxicity (not to mention the emergence of drug-resistant parasites), all of which has prompted current search for new strategies to improve their safety. This work assesses the effectiveness and safety (toxicity including new aspects related with immunotoxicity not reported previously) of two different meglumine antimoniate formulations using an in vitro and in vivo murine model. The results evidence that although both injectable formulations induce an equally efficient (clearance of intracellular parasites), both give rise to adverse effects, including a preferential immunomodulation on Balb/c mice and in a lesser proportion on ICR mice. These results are comparable to human trials reporting variable reactions when following the same treatment regimen. The model presented herein is proposed as a tool for evaluating the effectiveness and safety of meglumine antimoniate-based antileishmanial formulations.


Asunto(s)
Antiprotozoarios/farmacología , Leishmaniasis Cutánea/tratamiento farmacológico , Meglumina/farmacología , Compuestos Organometálicos/farmacología , Animales , Antiprotozoarios/administración & dosificación , Antiprotozoarios/toxicidad , Modelos Animales de Enfermedad , Femenino , Inmunomodulación/efectos de los fármacos , Técnicas In Vitro , Inyecciones Intramusculares , Meglumina/administración & dosificación , Meglumina/toxicidad , Antimoniato de Meglumina , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos ICR , Compuestos Organometálicos/administración & dosificación , Compuestos Organometálicos/toxicidad , Especificidad de la Especie , Pruebas de Toxicidad
16.
Cuad. psicol. deporte ; 18(1): 195-208, ene. 2018. tab
Artículo en Español | IBECS (España) | ID: ibc-171120

RESUMEN

El objetivo de esta investigación fue analizar las propiedades psicométricas de la versión en castellano del SMS adaptado a la Danza en su versión de 3, 5 y 7 factores. Se utilizó una muestra de 174 alumnos (165 de sexo femenino=94,8%; 9 de sexo masculino=5,2%) con edades comprendidas entre 10-17 años (M=11,37; DT=,862).Todos los alumnos pertenecen a los cinco Conservatorios Profesionales de Danza en Andalucía de las provincias de Granada, Almería, Cádiz, Córdoba y Sevilla. Como instrumento se utilizó la escala Sport Motivation Scale validada al castellano y para Educación Física adaptándola a la Danza, así como algunos datos sociodemográficos. Se analizaron las propiedades psicométricas de esta escala junto a un análisis exploratorio y confirmatorio en sus tres versiones. Los análisis apoyan que los tres modelos podrían ser utilizados según los datos del análisis factorial exploratorio, aunque sugerimos como mejor opción el modelo de siete factores en el ámbito de la Danza (AU)


The aim of this research was to analyze the psychometric properties of the SMS Spanish version adapted to Dance (SMS-D) in its three models of 3, 5 and 7 factors. Aged 10 to 17 years (M = 11.37, SD = .862), a sample of 174 students (9 Male = 5.2%; 165 Female = 94.8%) was used All students belong to the five Professional Conservatories of Dance in Andalusia the provinces of Granada, Almería, Cádiz, Córdoba and Sevilla. As the Sport Motivation Scale instrument validated the Spanish Physical Education and adapting it to the Dance, as well as some demographic data scale is used. The psychometric properties of this scale were analyzed with exploratory and confirmatory analysis in its three versions. The analyzes support the three models could be used according to data from exploratory factor analysis, although we suggest as the best option the seven-factor model in the field of dance (AU)


O objetivo desta pesquisa foi analisar as propriedades psicométricas da versão castelhana SMS adaptado à dança (SMS-D) em seus três modelos de fatores 3, 5 e 7. Idade entre 10 e 17 anos (M = 11.37; DT = .862), uma amostra de 174 alunos (9 do sexo Masculino = 5.2% 165 Feminino = 94.8%) foi utilizado pertence a estudantes .Todos cinco Conservatórios profissionais de Dança na Andaluzia as províncias de Granada, Almería, Cádiz, Córdoba e Sevilha. Como o instrumento Sport Motivation Scale validou o castelhano Educação Física e adaptando-o à Dança, bem como alguma escala de dados demográficos foi usado. Foram analisadas as propriedades psicométricas desta escala com uma análise exploratória e confirmatória em três versões. As análises apoiar os três modelos poderiam ser utilizados de acordo com dados da análise fatorial exploratória, embora sugerimos como a melhor opção do modelo de sete fator no campo da dança (AU)


Asunto(s)
Humanos , Masculino , Femenino , Niño , Adolescente , Psicometría/métodos , Motivación , Baile , Escalas de Valoración Psiquiátrica Breve , Análisis Factorial , Encuestas y Cuestionarios , Análisis de Datos , Psicología del Deporte/métodos
17.
Phys Rev Lett ; 99(14): 146808, 2007 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-17930703

RESUMEN

We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural properties determined by cross-sectional scanning tunneling microscopy measurements. The observed oscillation magnitude of the magnetic moment per electron is remarkably large for the topology of our nanostructures, which are singly connected and exhibit a pronounced shape asymmetry.

18.
Microb Ecol ; 49(2): 282-90, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15965721

RESUMEN

Cryptococcus neoformans, the etiological agent of cryptococcosis, has been associated with avian droppings and certain trees in different countries, including Colombia. C neoformans environmental isolates were obtained in urban areas in Bogotá, Colombia, and the strains recovered were phenotypically characterized. Attempts to determine the ecological conditions (micro- and macroclimatic) possibly related to their habitat were also undertaken. Four hundred and eighty samples from bark, soil around trunk bases, and detritus inside hollows of 32 trees were collected in three urban areas during a 5-month period, as well as 89 avian droppings samples from different places. Of plant samples, 6.7% collected from nine tree species yielded C. neoformans var. gattii, serotype B strains in 99% of the cases, and C. neoformans var. grubii, serotype A in 1%. The yeast was more frequently recovered from bark than from soil or detritus inside hollows, and from trees with hollows or rotted wood rather than from trees in which birds nest. C. neoformans was present with higher frequency and density in the rainy season than in the dry season; we found that slightly higher temperature and humidity values of the microhabitat, as compared to those of the environment, favored fungal occurrence, but the phenological state of the tree did not. Of dropping samples, 7.9% yielded C. neoformans strains, all of them C. neoformans var. grubii, serotype A. The yeast was obtained more frequently from dry droppings than from moist ones, but neither the sunlight exposure nor the site of collection of samples was correlated with this occurrence. Population density was significantly higher in droppings than in tree samples. Under laboratory conditions, isolates of different serotype showed similar capsular sizes. Water content and pH ranges were wide and did not show any significant difference between positive and negative samples.


Asunto(s)
Cryptococcus neoformans/clasificación , Cryptococcus neoformans/aislamiento & purificación , Animales , Aves/microbiología , Colombia , Ecosistema , Heces/microbiología , Fenotipo , Plantas/microbiología , Estaciones del Año
19.
J Biomed Mater Res ; 58(5): 505-10, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11505424

RESUMEN

The practice of single use devices (SUD) recycling raises public health concerns, primarily with regard to the potential risks of infection and device malfunction. These concerns have led to a Food and Drug Administration (FDA) revision of the present regulations. The purpose of our work is to identify different material parameters that could contribute to the health risks associated with the practice of reprocessing PVC catheters for use in other patients. Ethylene oxide hospital-reprocessed central venous catheter samples were obtained from the stock of a health-care institution. One device trademark was selected, and samples that had been used 8 and 24 times were compared with new ones. In order to determine the total percentage of extractables, supercritical fluid extraction (SFE) was used, and off-line gas-chromatography-flame-ionization detection (GC-FID) was employed for identification and quantitation of bis-(2-ethyl hexil)phthalate (DEHP). Storage modulus (E') and dissipation factor (tan delta curves were obtained by dynamic mechanical analysis (DMA). Successive catheter recycles produced increased plasticizer loss, increased glass transition temperature (T(g)) and E', widening of tan delta curve with a simultaneous shift to higher temperature, small decrease of weight average molecular weight (M(w)), increased surface roughness, and increased appearance of surface grooves (severe damage). The magnitude of biomaterial parameter changes measured suggests that reuse could alter the original device performance. Examples of possible adverse clinical events include leaching of toxic agents, device rigidization or breakage, increased catheter protein retention, or the promotion of bacterial adhesion by device topography modification.


Asunto(s)
Materiales Biocompatibles/efectos adversos , Catéteres de Permanencia , Dietilhexil Ftalato/análisis , Equipo Reutilizado , Óxido de Etileno/química , Cloruro de Polivinilo/química , Catéteres de Permanencia/provisión & distribución , Cromatografía de Gases/métodos , Cromatografía en Gel/métodos , Cromatografía con Fluido Supercrítico/métodos , Frío , Falla de Equipo , Ionización de Llama/métodos , Calor , Humanos , Control de Infecciones , Microscopía Electrónica de Rastreo , Medición de Riesgo , Factores de Riesgo , Esterilización
20.
Sudhoffs Arch ; 62(4): 359-77, 1978.
Artículo en Inglés | MEDLINE | ID: mdl-153605

Asunto(s)
Historia Antigua
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