La manipulación de objetos micrométricos a nivel individual es uno de los campos de investigación mas relevantes, ya que estas técnicas se pueden aplicar al manejo de material biológico. El objetivo de este artículo es el de presentar un microsistema disentilde;ado para la micromanipulación de partículas. El principio de funcionamiento de este dispositivo es la dielectroforésis, la cual consiste en el movimiento lateral de material eléctricamente neutro bajo la influencia de campos eléctricos no uniformes. En la práctica, el dispositivo se fabricó sobre un substrato de silicio en el cual se depositaron microelectrodos interdigitados hechos de platino. Además, las paredes de la microcámara fueron fabricadas con una resina fotocurable, lo cual permite un volumen constante de la muestra bajo estudio durante la experimentación. Igualmente, el circuito integrado se probó con microesferas de poliestireno de 4,2μm de diámetro. En este trabajo se presentan algunos resultados de dielectroforésis común y aglomerado de partículas. El patrón de los microagregados es consistente con la distribución del campo eléctrico sobre los electrodos, el cual se calculó con el método de los elementos finitos.

Manipulation of micrometric objects at the single level is one of the most important research fields because these techniques can be applied to handle biological material. The objective of this paper consists of presenting a microsystem designed for particle microhandling. The operating principle of the device hinges upon dielectrophoresis, which is the lateral motion of electrical neutral matter under the influence of non-uniform electric fields. In practice, the device was made on a silicon substrate onto which interdigitated castellated microelectrodes made of platinum were patterned by lift-off. Moreover, the microchamber walls were patterned in a photocurable resin which allows a constant sample volume during the experiments. Besides this, the chip was tested with polystyrene microspheres of 4.2 μm in diameter and some results of common dielectrophoresis and particle clustering are also presented. Microparticle aggregation patterns are consistent with the electric field profile calculated by the finite element method over the electrode surface.

Este artigo descreve a modelagem e teste experimental de uma rede de microeletrodos em cremalheira cujo objetivo é o manuseio de células biológicas, com base em dieletroforese comum. O microsistema proposto foi desenvolvido empregando eletrodos de platina depositados por técnicas de 'lift-off', micro-usinagem em silício e litografia com foto-resina. Uma vez fabricado o microdispositivo, este foi testado utilizando a Escherichia coli como modelo de biopartículas. Dieletroforese positiva pode ser observada com as células selecionadas para freqüências acima de 100kHz, e efeitos eletro-hidrodinâmicos foram observados como o fenômeno dominante para menores freqüências. Como resultado, a dieletroforese negativa não pode ser observada pois sua ocorrência se sobrepõe a efeitos eletro-hidrodinâmicos; i.e. a força de arraste viscoso atuando sobre as partículas é superior à força dieletroforética para freqüências em que a dieletroforese negativa deveria ocorrer. Os experimentos ilustram a conveniência deste tipo de micro-dispositivo para o micromanuseio de objetos biológicos, abrindo a possibilidade de uso destas micro-redes com outras partículas biológicas. Além disto, o movimento líquido como resultado dos efeitos eletro-hidrodinâmicos deve ser levado em conta ao se desenhar micromanipuladores de partículas biológicas, e pode ser utilizado como mecanismo para limpar as superfícies dos eletrodos, que é um dos problemas mais importantes relacionados a este tipo de dispositivo.

This paper describes the modeling and experimental verification of a castellated microelectrode array intended tohandle biocells, based on common dielectrophoresis. The proposed microsystem was developed employing platinumelectrodes deposited by lift-off, silicon micromachining, and photoresin patterning techniques. Having fabricated the microdevice it was tested employing Escherichia coli as bioparticle model. Positive dielectrophoresis could be verified with the selected cells for frequencies above 100 kHz, and electrohydrodynamic effects were observed as the dominant phenomena when working at lower frequencies. As a result, negative dielectrophoresis could not be observed because its occurrence overlaps with electrohydrodynamic effects; i.e. the viscous drag force acting on the particles is greater than the dielectrophoretic force at frequencies where negative dielectrophoresis should occur. The experiments illustrate the convenience of this kind of microdevices to micro handling biological objects, opening the possibility for using these microarrays with other bioparticles. Additionally, liquid motion as a result of electrohydrodynamic effects must be taken into account when designing bioparticle micromanipulators, and could be used as mechanism to clean the electrode surfaces, that is one of the most important problems related to this kind of devices.

La micromanipulación de partículas biológicas es una operación frecuente en medicina y microbiología, y se ha dedicado una gran cantidad de trabajo para desarrollar técnicas de manipulación mas rápidas, baratas y eficientes. En este sentido, la tecnología de microsistemas juega un papel importante ya que se puede utilizar para fabricar manipuladores de micropartículas. En este articulo se describe el diseño y fabricación de un microsistema para la manipulación de objetos biológicos, basado en el efecto dielectroforetico. También se discute la selección de la alternativa tecnológica mas adecuada dentro de las disponibles. El diseño propuesto, es un microsistema completo que incluye interfases eléctrica, óptica y fluidica, y se desarrolló empleando oro y platino como metales para los electrodos, micro mecanizado del silicio y técnicas de fotocurado de resinas fotosensibles. De la misma forma se describe la estructura de los microelectrodos desarrollados al igual que el circuito integrado resultante.

Biological particle microhandling is a common operation in medicine and microbiology, and a lot of research work has been addressed to develop faster, cheaper and more efficient manipulation techniques. In this way, microsystem technologies play an important role because they can be used to fabricate microparticle manipulators. This paper describes the design and fabrication of a microsystem to handle biological objects, based on the dielectrophoretic effects. The development of the right technological option among the possibilities at disposal is also discussed. The proposed design, a whole microsystem including electrical, optical and fluidic interfaces, was developed employing gold and platinum metals, silicon micromachining, and photoresin patterning techniques. Furthermore, the structure of the utilized microelectrode arrays, as well as the resulting microchip are also reported.

Travelling-wave dielectrophoretic phenomena involving cell detection and manipulation are very interesting for biomedical and biotechnological applications. However, electrohydrodynamic phenomena may interfere with the action of dielectrophoresis. The main goal of our study is to calculate the interplay of these effects. In so doing, we have been able to go beyond the order-of-magnitude estimations, which were available in the literature. In this framework we have taken into account the effects of using square signals, which calls for a calculation of the combined polarisability effects due to the superposition of different frequencies. Thermal gradients are also a triggering agent of electrohydrodynamic effects. We have undertaken the pertinent thermal simulations with a concern for the influence of different boundary conditions. The dynamics of the thermal fields were also assessed in order to estimate the characteristic times of electrohydrodynamic phenomena. All these results have been used in a study of the fluid flow pattern motion at different frequencies and its influence on the particle behaviour.

Objectives: To investigate the effectiveness of brief interventions to reduce alcohol intake in traffic casualties with a positive blood alcohol concentration. Methods: Nine hundred forty-eight eligible casualties (97.6% of eligible casualties within a universe of 1106) were screened for alcohol and 126 (13.3%) were identified as positive. Interventions were performed in 85, randomly allocated to a minimal intervention (simple advice) or a brief intervention (motivational intervention). Telephone follow-up was scheduled for months 3, 6 and 12. The present study reports the results of follow-up at month 3. Results: Fifty-seven patients (67%) were followed up at month 3. A total of 73.7% had reduced their alcohol intake and this percentage was greater in the group who underwent the brief intervention (p = 0.06; effect size 0.5) and among heavy drinkers (p < 0.05). Conclusions: The data indicate the effectiveness of the brief intervention, although the sample size does not allow definitive conclusions to be drawn.

Objetivos: Investigar la efectividad de las intervenciones breves para reducir el consumo de alcohol en los pacientes lesionados por accidente de tráfico con alcoholemia positiva. Métodos: Se cribó la presencia de alcohol en 948 lesionados en accidente de tráfico (el 97,6% de los elegibles de un universo de 1.106), con 126 (13,3%) positivos. Se intervino en 85 individuos, aleatoriamente distribuidos en intervención mínima (consejo simple) e intervención breve (intervención de tipo motivacional), y se programó un seguimiento telefónico a los 3, 6 y 12 meses. En este trabajo se presentan los resultados del seguimiento a los 3 meses. Resultados: A los 3 meses se ha seguido a 57 pacientes (67%). EL 73,7% ha reducido el consumo, porcentaje que fue mayor en el grupo intervención breve (p = 0,06; tamaño del efecto, 0,5) y en los incluidos en la categoría de los bebedores de riesgo (p < 0,05). Conclusiones: Se registró la efectividad de la intervención breve, aunque el tamaño de la muestra no permite establecer conclusiones definitivas.

Objectives: To investigate the effectiveness of brief interventions to reduce alcohol intake in traffic casualties with a positive blood alcohol concentration. Methods: Nine hundred forty-eight eligible casualties (97.6% of eligible casualties within a universe of 1106) were screened for alcohol and 126 (13.3%) were identified as positive. Interventions were performed in 85, randomly allocated to a minimal intervention (simple advice) or a brief intervention (motivational intervention). Telephone follow-up was scheduled for months 3, 6 and 12. The present study reports the results of follow-up at month 3. Results: Fifty-seven patients (67%) were followed up at month 3. A total of 73.7% had reduced their alcohol intake and this percentage was greater in the group who underwent the brief intervention (p = 0.06; effect size 0.5) and among heavy drinkers (p < 0.05). Conclusions: The data indicate the effectiveness of the brief intervention, although the sample size does not allow definitive conclusions to be drawn.

Objetivos: Investigar la efectividad de las intervenciones breves para reducir el consumo de alcohol en los pacientes lesionados por accidente de tráfico con alcoholemia positiva. Métodos: Se cribó la presencia de alcohol en 948 lesionados en accidente de tráfico (el 97,6% de los elegibles de un universo de 1.106), con 126 (13,3%) positivos. Se intervino en 85 individuos, aleatoriamente distribuidos en intervención mínima (consejo simple) e intervención breve (intervención de tipo motivacional), y se programó un seguimiento telefónico a los 3, 6 y 12 meses. En este trabajo se presentan los resultados del seguimiento a los 3 meses. Resultados: A los 3 meses se ha seguido a 57 pacientes (67%). EL 73,7% ha reducido el consumo, porcentaje que fue mayor en el grupo intervención breve (p = 0,06; tamaño del efecto, 0,5) y en los incluidos en la categoría de los bebedores de riesgo (p < 0,05). Conclusiones: Se registró la efectividad de la intervención breve, aunque el tamaño de la muestra no permite establecer conclusiones definitivas.

Objective: To identify the differential features of positive blood alcohol level (BAL) in people injured in road crashes who were attended an acute care service. Methods: Cross-sectional study of persons aged 18 years old or older injured in motor vehicle crashes who were attended in the Traumatology Emergency Department of Vall d'Hebron Hospital (Spain) between July 2001 and February 2002. Results: The study sample included 431 patients. A positive alcohol test was found in 13.7% of the sample. A statistically significant and independent association was found between positive BAL and male sex (odds ratio [OR] = 2.5 [95% CI, 1.3-5.4]), hospital admission (OR = 2.7 [95% CI, 1.3-5.4]), being attended on a weekend (OR = 3.7 [95% CI, 2.0-6.9]) and being attended during the night and early morning (OR = 4.6 [95% CI, 2.0-10.3]) or in the morning (OR = 3.6 [95% CI, 1.5-8.4]). Conclusions: The present study identifies a subgroup of people injured in motor vehicle crashes with a greater likelihood of positive BAL, in whom more active screening and secondary prevention activities should be implemented within traumatology and acute care setting.

Objetivo: Identificar de las características diferenciales de positividad a alcohol en lesionados en accidentes de tráfico atendidos en un servicio de urgencias hospitalario. Métodos: Estudio transversal con sujetos de 18 años o mayores, lesionados en accidentes de tráfico, atendidos en el servicio de urgencias del Área de Traumatología del Hospital Vall d'Hebron, entre julio de 2001 y febrero de 2002. Resultados: La muestra incluyó a 431 pacientes. El 13,7% resultó positivo a la determinación de alcohol: se hallaron diferencias en los varones (odds ratio [OR] = 2,5; IC del 95%, 1,3-5,4) y los lesionados ingresados (OR = 2,7; IC del 95%, 1,3-5,4) y en los que fueron asistidos en fin de semana o festivo (OR = 3,7; IC del 95%, 2,0-6,9), de noche y madrugada (OR = 4,6; IC del 95%, 2,0-10,3) o durante la mañana (OR = 3,6; IC del 95%, 1,5-8,4). Conclusiones: Se ha determinado la existencia de subgrupos de lesionados en accidentes de tráfico con una mayor probabilidad de alcoholemia positiva, en los cuales deberían aplicarse programas de cribado y prevención secundaria más activos desde los servicios de urgencias y de traumatología.

Objective: To identify the differential features of positive blood alcohol level (BAL) in people injured in road crashes who were attended an acute care service. Methods: Cross-sectional study of persons aged 18 years old or older injured in motor vehicle crashes who were attended in the Traumatology Emergency Department of Vall d'Hebron Hospital (Spain) between July 2001 and February 2002. Results: The study sample included 431 patients. A positive alcohol test was found in 13.7% of the sample. A statistically significant and independent association was found between positive BAL and male sex (odds ratio [OR] = 2.5 [95% CI, 1.3-5.4]), hospital admission (OR = 2.7 [95% CI, 1.3-5.4]), being attended on a weekend (OR = 3.7 [95% CI, 2.0-6.9]) and being attended during the night and early morning (OR = 4.6 [95% CI, 2.0-10.3]) or in the morning (OR = 3.6 [95% CI, 1.5-8.4]). Conclusions: The present study identifies a subgroup of people injured in motor vehicle crashes with a greater likelihood of positive BAL, in whom more active screening and secondary prevention activities should be implemented within traumatology and acute care setting.

Objetivo: Identificar de las características diferenciales de positividad a alcohol en lesionados en accidentes de tráfico atendidos en un servicio de urgencias hospitalario. Métodos: Estudio transversal con sujetos de 18 años o mayores, lesionados en accidentes de tráfico, atendidos en el servicio de urgencias del Área de Traumatología del Hospital Vall d'Hebron, entre julio de 2001 y febrero de 2002. Resultados: La muestra incluyó a 431 pacientes. El 13,7% resultó positivo a la determinación de alcohol: se hallaron diferencias en los varones (odds ratio [OR] = 2,5; IC del 95%, 1,3-5,4) y los lesionados ingresados (OR = 2,7; IC del 95%, 1,3-5,4) y en los que fueron asistidos en fin de semana o festivo (OR = 3,7; IC del 95%, 2,0-6,9), de noche y madrugada (OR = 4,6; IC del 95%, 2,0-10,3) o durante la mañana (OR = 3,6; IC del 95%, 1,5-8,4). Conclusiones: Se ha determinado la existencia de subgrupos de lesionados en accidentes de tráfico con una mayor probabilidad de alcoholemia positiva, en los cuales deberían aplicarse programas de cribado y prevención secundaria más activos desde los servicios de urgencias y de traumatología.

This article is centered around the issue of gender and music. Music, as a means of communication, also contributes to the social construction of reality. If we are interested in music as a sociocultural phenomenon, the issue of gender constitutes a special dimension which cannot be ignored. Throughout this article, I give some results of an inquiry carried out on young people of Barcelona in autumn of 1995. Among the different objectives of this inquiry was to obtain information about meaning and functions of music in Catalan society. Some of the questions dealt with the role played by music in gender relations. Concretely, the results of this inquiry provide us information about the use of music as strategy of gender identity as well about functions music can play in a society which is characterized by the asymmetrical nature of gender relations; i.e. music as expression and at the same time as resource of maintenance of specific gender relations.

Este artigo trata da problemática da relação entre gênero e música. Sabemos que a música como meio de comunicação contribui também para a construção social da realidade; se nos interessamos pela música como fenômeno sócio-cultural, então o aspecto de gênero constitui uma dimensão que não pode ser ignorada. Ao longo deste artigo, apresentarei alguns dados relativos a uma pesquisa tipo survey realizada com jovens barcelonenses durante o outono de 1995. Entre os diferentes objetivos da pesquisa buscava-se obter informações sobre o significado e funções da música na sociedade catalã, com algumas questões orientadas para tratar do papel que desempenha a música nas relações de gênero. Concretamente, os resultados da amostra nos aportam dados sobre o uso da música como estratégia de identidade de gênero, assim como sobre as funções que pode exercer a música como expressão e ao mesmo tempo recurso de manutenção das relações de gênero, que em nossa sociedade caracterizam-se pela sua natureza assimétrica.