Resumen Se estudian las propiedades dinámicas de un modelo de suspensión coloidal bidimensional cuyas partículas son depositadas lentamente sobre un sustrato unidimensional bajo la acción de un campo externo. Una vez que las partículas son depositadas en el sustrato pueden difundirse lateralmente sobre este último. Usando un modelo analítico basado en las ecuaciones de Langevin y de Fokker-Plank se estudia la dinámica de una partícula en la suspensión y sobre el sustrato. En particular, se calculan la tasa de deposición promedio sobre el sustrato, ℱ, así como también la constante de difusión de las partículas sobre el sustrato, D. Los resultados del modelo analítico propuesto presentan un buen acuerdo con los encontrados usando simulaciones numéricas basadas en dinámica molecular. Este modelo sencillo permite explorar la posibilidad de usar coloides para la formación de estructuras mediante la técnica de crecimiento epitaxial, la cual es relevante en distintos campos de aplicación.

Abstract We analyze the dynamical properties of a two-dimensional colloidal suspension model, whose particles are slowly deposited on a one-dimensional substrate due to the influence of an external field. Once the particles are deposited on the substrate they can laterally diffuse on it. Using an analytical model based on the Langevin and the Fokker- Plank equations, the dynamics of a particle in the suspension and on the substrate, are studied. In particular, we evaluate the average deposition rate on the substrate, ℱ, as well as the diffusion constant of the particles on the substrate D. The proposed analytical model gives results that agree well with those found using numerical simulations based on molecular dynamics. This simple model allows to explore the possibility to use colloids for the formation of structures through the epitaxial growth technique, which is relevant in several application fields.

Resumo A ecologia da dispersão de sementes é importante para entender a distribuição e abundância das espécies vegetais. Investigamos os fatores relacionados à elevada abundância de B. tomentosa no Parque Estadual da Serra Azul (PESA) avaliando aspectos da dispersão de sementes. Estimamos a produção de frutos e realizamos experimentos de remoção de frutos. Fizemos observações diurnas e noturnas sobre a frugivoria e testamos a germinação de sementes. A frutificação ocorreu na estação seca totalizando 1.365.015 ± 762.670 frutos.ha–1. Oito espécies de animais utilizaram frutos de B. tomentosa. Anta (Tapirus terrestris) foi considerada o principal dispersor. Saúvas (Atta laevigata e Atta sexdens) participaram na limpeza das sementes e como dispersores ocasionais. O besouro Amblycerus insuturatus, arara-canindé (Ara ararauna) e arara-vermelha (Ara chloropterus) foram considerados predadores pré-dispersão. Sementes despolpadas manualmente tiveram maior percentual (100%) e velocidade de geminação (4,2 sementes.dia–1) que aquelas com polpa. Sementes encontradas nas fezes de antas apresentaram 40,0% de germinação e sementes sem polpa 25,0%. A massiva produção de frutos, baixa taxa de predação de sementes, além da eficiente dispersão por antas, antes da estação chuvosa, favorecem o recrutamento e são fatores que contribuem de forma decisiva para a elevada abundância de B. tomentosa observada no cerrado do PESA.

Abstract The ecology of seed dispersal is critical to understand the patterns of distribution and abundance of plant species. We investigated seed dispersal aspects associated with the high abundance of Buchenavia tomentosa in the Serra Azul State Park (PESA). We estimated fruit production and conducted fruit removal experiments. We carried out diurnal and nocturnal observations on frugivory as well as germination tests. Fruiting occurred in the dry season and totaled 1,365,015 ± 762,670 fruits.ha–1. B. tomentosa fruits were utilized by eight animal species. The lowland tapir (Tapirus terrestris) was considered the main seed disperser. Leafcutter ants (Atta laevigata and Atta sexdens) participated in the seed cleaning and occasionally dispersed seeds. The beetle Amblycerus insuturatus, blue-and-yellow macaw (Ara ararauna) and red-and-green macaw (Ara chloropterus) were considered pre-dispersal seed predators. The seeds manually cleaned presented higher germination rate (100%) and speed index (4.2 seeds.d–1) than that of seeds with pulp. Germination of seeds found in tapirs’feces was 40%, while for the seeds without pulp it was 25%. The high abundance of B. tomentosa in the cerrado of PESA may be due to massive fruit production, low rates of seed predation, and efficient seed dispersal by tapirs, occurring before the rains which promote germination and recruitment of this species.

Volcanic ash deposits are excellent stratigraphical and chronological markers as they can be dispersed hundreds of kilometers from its source, but sometimes the correlation with the source can be problematic. While most of the studies support these correlations in whole rock geochemical analyses, juvenile volcanic particles have great heterogeneity in fragment shapes, texture, and groundmass and mineral phases composition. Previous works on volcanic deposits identified in a lacustrine sedimentary sequence of lake Nahuel Huapi allowed the identification of products from the 1960 Cordón Caulle volcanic complex eruption, showing high variability in the juvenile volcanic particles, like white and brown pumice, scoria and glass shards, with variation in the whole rock composition. With this information as a background, this paper presents the first morphological, textural and compositional analyses of different juvenile products in order to identify the origin of morphological and whole rock geochemical variations. The results allowed the association of such differences with variations in crystal content and size, shape and distribution of vesicles. Such variations, in turn, were related to processes of fractionation previous to the 1960 Cordón Caulle eruption, thus providing valuable information to use these layers as chronostratigraphic markers.

Los depósitos de cenizas volcánicas son excelentes marcadores estratigráficos y cronológicos ya que pueden ser dispersados a cientos de kilómetros de su fuente. Sin embargo, su correlación puede ser problemática. Si bien la mayoría de los estudios basan estas correlaciones en análisis geoquímicos de roca total, las partículas volcánicas juveniles poseen gran heterogeneidad en cuanto a la forma de los fragmentos, textura y composición de la matriz y las fases minerales. Trabajos previos en niveles volcánicos identificados en una secuencia del lago Nahuel Huapi permitieron identificar los productos de la erupción del año 1960 del Sistema Cordón Caulle, presentando una gran variabilidad en el tipo de partículas volcánicas juveniles identificadas, como pómez blanca, marrón, escorias y trizas vítreas, con variaciones en la composición de roca total de cada tipo de partícula. Con esta información como base, en el presente trabajo se presentan los primeros análisis morfológicos, texturales y composicionales de los diferentes productos juveniles con el objeto de identificar el origen de las variaciones morfológicas y de geoquímica de roca total de las mismas. Los resultados permitieron asociar dichas diferencias a variaciones en el contenido de cristales y tamaño, forma y distribución de vesículas. Dicha variación, a su vez, fue relacionada a procesos de fraccionamiento previos a la erupción de 1960 del Sistema Cordón Caulle, generando información de valiosa utilidad para el uso de estos niveles como marcadores cronoestratigráficos.

Olive oil extraction generates large amounts of olive mill residues (DOR) which may be used as organic fertilizer. The influence of a combination of physical fractionation and saprobe fungal incubation on the phytotoxicity of DOR was studied. The physical fractions of DOR, obtained following extraction using ethyl acetate (EDOR) and water (ADOR) were less phytotoxic than DOR with respect to the shoot dry weight of tomato. There was no relationship between the total phenol content of the different DOR physical fractions and their phytotoxicity. The saprophytic fungus Coriolopsis rigida reduced DOR and ADOR phytotoxicity and eliminated the phytotoxicity of EDOR. However, unlike the physical treatments of DOR, the decrease in the phenol content of EDOR and ADOR caused by C. rigida was closely paralleled to the decrease in their phytotoxicity. After 30 days of incubation, C. rigida was able to eliminate the phytotoxicity of EDOR on tomato plants grown in the field.

INTRODUCCIÓN: en muchas culturas, la madre es la responsable por excelencia del cuidado del bebé, en muchos casos el adulto más significativo, modelo de referencia imitable y transmisora principal de cultura, incluyendo conocimientos y prácticas de salud. El objetivo fue explorar en un grupo de gestantes de la ciudad de Medellín participantes de un programa de intervención, los significados con respecto a la salud bucal propia y de sus hijos. MÉTODOS: el abordaje metodológico fue la etnometodología; se aplicaron entrevistas semiestructuradas que fueron grabadas, transcritas y analizadas, agrupando las respuestas en recurrencias, divergencias, textos significativos y tendencias. RESULTADOS: las gestantes otorgan un significado importante a la boca, relacionado con la supervivencia y la estética; enfatizan en los dientes como parte integrante de la boca y consideran la salud bucal sinónimo de dientes sanos. El concepto de higiene bucal lo representan como higiene de los dientes, con cepillo y crema dental. La boca de su futuro hijo no es asunto de preocupación, aunque consideran importante su higiene, pero no en etapas tempranas. CONCLUSIONES: la boca como elemento fundamental de supervivencia, es un asunto reconocido por las entrevistadas. Los cuidados de la boca del bebé, adquieren importancia en relación con la aparición de los dientes. La seda dental, elemento necesario para la higiene de los dientes, no está incorporado en las prácticas de las gestantes, como tampoco una frecuencia del cepillado. La alfabetización en salud propone construir conocimiento que incida positivamente en el fomento y conservación de la salud.

INTRODUCTION:in many cultures, mothers are responsible for taking care of their babies, being the mother frequently the most significant adult, a model to follow, and the principal transmitter of culture, including health knowledge and practices. The objective of this study was to explore a group of pregnant women’s perceptions of their own oral health and that of their children. These women were all from Medellín, Colombia, and they were participating in one of the city’s intervention programs. METHODS:An ethno-methodological approach was used; therefore, semi-structured interviews were conducted, recorded, transcribed and analyzed, and the responses were classified according to four criteria: recurrence, divergence, tendencies, and significant meanings. RESULTS: pregnant mothers give significant importance to the mouth due to survival and esthetic reasons. They emphasize teeth over other parts of the mouth and think that oral health is synonymous to healthy teeth. The concept of oral hygiene is represented as cleaning the teeth with toothbrush and toothpaste. The mouth of their future child is not a matter of concern, and they consider oral hygiene important but not in early stages. CONCLUSIONS:the interviewed mothers recognize the mouth as an essential survival element. Care of the baby’s mouth gains importance as teeth appear. Dental floss, which is considered necessary as a cleaning element, is not used by pregnant women, not is it frequent tooth brushing. The claim of Oral Health Literacy is to build knowledge in order to promote and preserve health.

Protecting natural resources and reducing man-induced incidences of disappearance of species requires all our attention. Studies conducted on many threatened orchid species in different habitats do not delve into the relationship between these species and the pests present in the environment where they grow. This research provides orchid growers new information on Chrysomphalus ficus Ashmead incidence on the cuban orchid species Encyclia brevifolia. Based on systematic statistical monitoring of the conditions of Soroa Botanical Garden's Orchid Collection, the study yielded information that can be used as a reference for perfecting the strategy for conservation of this species by orchid growers and national botanical gardens. In addition, the pest population was observed and its presence on different plant organs was compared in function of time and temperature.

La intención de proteger los recursos naturales y disminuir las incidencias, catalizadas por el hombre, en la desaparición de muchas especies, requiere de toda nuestra atención. Los estudios realizados sobre las amenazas que ponen en peligro la existencia de muchas especies de orquídeas en diferentes hábitats, no profundizan en la relación existente de estas especies con las plagas presentes en el ambiente donde se desarrollan estas plantas. La presente investigación aporta a los cultivadores de orquídeas una nueva información acerca de la incidencia de Chrysomphalus ficus Ashmead. Sobre la especie de orquídea cubana Encyclia brevifolia. El análisis estadístico aplicado a la misma, ha obtenido importantes resultados. Este proceso se basó en el monitoreo sistemático estadístico para las condiciones del Jardín Botánico Orquideario Soroa, el cual arrojó importante información para los cultivadores de orquídeas y los Jardines Botánicos Nacionales, que puede ser utilizada como referencia en el perfeccionamiento de la estrategia trazada para la conservación de dicha especie. En la misma se muestra el comportamiento de la plaga comparativamente sobre los órganos de la planta en función del tiempo y de la temperatura.

In Chilean children the incidence of tuberculosis (TB) is low: 2.3/100.000 in younger than 15 years old (2005). This fact may explain that TB diagnosis is sometimes difficult to do in pediatric patients. Our aim was to describe the clinical forms of presentation of TB in children's hospital patients with confirmed TB diagnosis between the years 1989-2005. We carried out this retrospective analysis in 49 patients younger than 15 years old (mean: 5.8 years.); 65.5% of them had a history of contact with an active tuberculosis case. Twenty nine (59.1%) patients were diagnosed as pulmonary TB, 19 of them (65.5%) as primary pulmonary TB and the remainder 10 as post-primary pulmonary TB. Out of the 20 patients with extrapulmonary TB, adenitis was the most frequent (n = 8) followed by pleural effusion (n = 7). Chest x-ray was normal in 10 out of the 49 patients. Major x-ray pathological findings were: primary pulmonary TB 38.7% (n = 19), pleural effusion 14.3% (n = 7), and parenchyma air-space consolidation 10.2% (n = 5). We expect this study would contribute to make a much earlier diagnosis and treatment of TB in children

En Chile, la incidencia de tuberculosis (TBC) en la edad pediátrica es baja: 2,3/100.000 en menores de 15 años (2005). Este hecho puede explicar que a veces es difícil hacer el diagnóstico de TBC en pacientes pediátricos. Nuestro propósito fue describir las formas de presentación clínica de la TBC en pacientes del hospital de niños Roberto del Río, con diagnóstico confirmado de TBC entre los años 1989 y 2005. Efectuamos un análisis retrospectivo en 49 pacientes menores de 15 años (edadpromedio: 5,8 años.); 65,5% de ellos tenía antecedentes de contacto con TBC activa. A veintinueve pacientes (59,1%) se les diagnosticó TBC pulmonar, en 19 de ellos (65,5%) se diagnosticó complejo primario y en los 10 restantes la forma progresiva de TBC pulmonar. En los 20 pacientes con TBC extrapulmonar, la adenitis fue la forma más frecuente (n = 8), seguida por la pleuresía (n = 7). La radiografía de tórax fue normal en 10 de los 49 pacientes. Los principales hallazgos radiológicos fueron complejo primario TBC 38,7% (n = 19), derrame pleural 14,3% (n = 7), y condensación pulmonar 10,2% (n = 5). Esperamos que este estudio contribuya a efectuar más precozmente el diagnóstico y tratamiento de la TBC en niños

OBJETIVO: Descrever as impressões, experiências, conhecimentos, crenças e a receptividade de usuários de drogas injetáveis para participar das estratégias de testagem rápida para HIV. MÉTODOS: Estudo qualitativo exploratório foi conduzido entre usuários de drogas injetáveis, de dezembro de 2003 a fevereiro de 2004, em cinco cidades brasileiras, localizadas em quatro regiões do País. Um roteiro de entrevista semi-estruturado contendo questões fechadas e abertas foi usado para avaliar percepções desses usuários sobre procedimentos e formas alternativas de acesso e testagem. Foram realizadas 106 entrevistas, aproximadamente 26 por região. RESULTADOS: Características da população estudada, opiniões sobre o teste rápido e preferências por usar amostras de sangue ou saliva foram apresentadas junto com as vantagens e desvantagens associadas a cada opção. Os resultados mostraram a viabilidade do uso de testes rápidos entre usuários de drogas injetáveis e o interesse deles quanto à utilização destes métodos, especialmente se puderem ser equacionadas questões relacionadas à confidencialidade e confiabilidade dos testes. CONCLUSÕES: Os resultados indicam que os testes rápidos para HIV seriam bem recebidos por essa população. Esses testes podem ser considerados uma ferramenta valiosa, ao permitir que mais usuários de drogas injetáveis conheçam sua sorologia para o HIV e possam ser referidos para tratamento, como subsidiar a melhoria das estratégias de testagem entre usuários de drogas injetáveis.

OBJECTIVE: To describe perceptions, experiences, knowledge, beliefs and the willingness of injecting drug users to be HIV tested by using rapid tests. METHODS: A qualitative exploratory study was carried out among injecting drug users from December 2003 to February 2004 in five Brazilian cities, located in four regions of Brazil. A semi-structured interview guide containing both closed and open-ended questions was used to address perceptions about non-conventional testing procedures, and non-traditional ways to provide testing access to injecting drug users. A total of 106 interviews, about 26 per region, were conducted. RESULTS: Characteristics of the population studied, common thoughts about HIV rapid testing, preference for using blood or saliva specimens, and other testing preferences, were presented together with reported advantages and disadvantages of each option. The study findings showed that the use of rapid tests among these users is feasible and that they are willing to be tested using rapid HIV tests, especially if some issues related to privacy and reliability of the test could be addressed. CONCLUSIONS: The study findings showed that rapid tests may be well accepted for this population. These tests can be considered a valuable tool, allowing a more injecting drug users to learn their HIV status and possibly be referred to treatment and should support more effective testing strategies for them.

OBJETIVO: Descrever as impressões, experiências, conhecimentos, crenças e a receptividade de usuários de drogas injetáveis para participar das estratégias de testagem rápida para HIV. MÉTODOS: Estudo qualitativo exploratório foi conduzido entre usuários de drogas injetáveis, de dezembro de 2003 a fevereiro de 2004, em cinco cidades brasileiras, localizadas em quatro regiões do País. Um roteiro de entrevista semi-estruturado contendo questões fechadas e abertas foi usado para avaliar percepções desses usuários sobre procedimentos e formas alternativas de acesso e testagem. Foram realizadas 106 entrevistas, aproximadamente 26 por região. RESULTADOS: Características da população estudada, opiniões sobre o teste rápido e preferências por usar amostras de sangue ou saliva foram apresentadas junto com as vantagens e desvantagens associadas a cada opção. Os resultados mostraram a viabilidade do uso de testes rápidos entre usuários de drogas injetáveis e o interesse deles quanto à utilização destes métodos, especialmente se puderem ser equacionadas questões relacionadas à confidencialidade e confiabilidade dos testes. CONCLUSÕES: Os resultados indicam que os testes rápidos para HIV seriam bem recebidos por essa população. Esses testes podem ser considerados uma ferramenta valiosa, ao permitir que mais usuários de drogas injetáveis conheçam sua sorologia para o HIV e possam ser referidos para tratamento, como subsidiar a melhoria das estratégias de testagem entre usuários de drogas injetáveis.

OBJECTIVE: To describe perceptions, experiences, knowledge, beliefs and the willingness of injecting drug users to be HIV tested by using rapid tests. METHODS: A qualitative exploratory study was carried out among injecting drug users from December 2003 to February 2004 in five Brazilian cities, located in four regions of Brazil. A semi-structured interview guide containing both closed and open-ended questions was used to address perceptions about non-conventional testing procedures, and non-traditional ways to provide testing access to injecting drug users. A total of 106 interviews, about 26 per region, were conducted. RESULTS: Characteristics of the population studied, common thoughts about HIV rapid testing, preference for using blood or saliva specimens, and other testing preferences, were presented together with reported advantages and disadvantages of each option. The study findings showed that the use of rapid tests among these users is feasible and that they are willing to be tested using rapid HIV tests, especially if some issues related to privacy and reliability of the test could be addressed. CONCLUSIONS: The study findings showed that rapid tests may be well accepted for this population. These tests can be considered a valuable tool, allowing a more injecting drug users to learn their HIV status and possibly be referred to treatment and should support more effective testing strategies for them.

Because of the unshifted type of recorded amplitude gratings, adaptive interferometers based on dynamic population gratings in Er-doped fibers with saturable absorption demonstrate an essentially quadratic response and, as a result, are not sensitive enough to detect a small object displacement (<< λ/4), and cannot distinguish the displacement direction. We propose, and experimentally demonstrate, two techniques for their linearization which are based on externally introduced phase off-set between the recording interference pattern and the recorded grating. In the transient technique, the application of a fast <img src="../../../../img/revistas/rmf/v53n2/a10s3.jpg">/2 phase jump in the detected wave makes the system response linear during the transient time of the grating formation τ 9 (typically of a millisecond-submillisecond scale in Er-doped fibers). In the continuous technique, the introduction of a permanent frequency off-set ΔΩ0 <img src="../../../../img/revistas/rmf/v53n2/a10s1.jpg">into the detected wave linearizes the system response permanently.

La mezcla de dos ondas transitorias, empleando rejillas dinámicas de población en fibras ópticas dopadas con erbio, es atractiva para aplicaciones de detección adaptativa de vibraciones mecánicas. Dichas rejillas dinámicas pueden ser grabadas en el intervalo espectral de absorción fundamental del Er3+ 1480-1580 nm utilizando láseres de onda continua con potencias inferiores a 1 mW y poseen tiempos característicos de formación del orden de τ 9 <img src="../../../../img/revistas/rmf/v53n2/a10s2.jpg">10-0.1 ms. Debido a la naturaleza no desplazada de las rejillas de amplitud grabadas, la configuración interferométrica muestra esencialmente una respuesta del tipo cuadrático, y como resultado, carece de sensibilidad y no es posible distinguir entre desplazamientos de direcciones opuestas de una superficie. A continuación proponemos y demostramos dos técnicas de linealización de la respuesta: del tipo transitorio, mediante la aplicación de un salto de fase auxiliar de <img src="../../../../img/revistas/rmf/v53n2/a10s3.jpg">/2 del patrón de interferencia; y del tipo continuo, la cual utiliza un desplazamiento continuo del patrón de interferencia a la frecuencia angular óptima ΔΩ0<img src="../../../../img/revistas/rmf/v53n2/a10s1.jpg">.

Los algoritmos de aprendizaje basados en Funciones Núcleo, particularmente las Máquinas de Soporte Vectorial (MSV), han proporcionado buenos resultados en problemas de clasificación con patrones de entrada no separables linealmente. El uso de las Funciones Núcleo permite aplicar estos algoritmos de inferencia incluso sobre información proveniente de un conjunto sin estructura de espacio euclideo. Al considerar una Función Núcleo, los datos se proyectan de forma implícita sobre un nuevo espacio de características cuya estructura es exportada hacia el espacio de origen. En este trabajo se analiza una Función Núcleo que actúa sobre datos que pertenecen a un Espacio Cualitativo de Ordenes de Magnitud Absolutos. El diseño de esta Función Núcleo está inspirado en recientes métodos elaborados sobre Máquinas Núcleo para espacios discretos de trabajo. Como ilustración se presenta una aplicación de estos sistemas de aprendizaje en el campo financiero, concretamente en la modelización del riesgo de crédito. Se estudia los resultados de predicción de riesgo crediticio de un conjunto de empresas que entregan información pública al mercado. Para ello se utilizan variables económico-financieras de las compañías y su clasificación de riesgo emitida por una conocida evaluadora del mercado financiero.