990 resultados para Social biology
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Recurso para el profesor que acompaña al libro de texto del alumno para preparar el Certificado de Educación Secundaria en el Caribe (CSEC). Trata de los organismos vivos y el medio ambiente, los procesos de vida, la herencia y la variación, la enfermedad y su impacto en los seres humanos; el impacto de las prácticas de salud en el medio ambiente. Tiene notas para el profesor y hojas de trabajo para los alumnos.
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Texto de biología para preparar el Certificado de Educación Secundaria del Caribe (CSEC). Está estructurado en seis secciones temáticas con un número variable de capítulos cada una : sección A, los organismos vivos y el medio ambiente; sección B, los procesos de vida; sección C, la herencia y la variación, sección D, la enfermedad y su impacto en los seres humanos; Sección E, el impacto de las prácticas de salud en el medio ambiente. Cada sección empieza con una visión general de los capítulos, que comienzan con una lista de objetivos. Cada capítulo tiene un resumen para reforzar lo aprendido, un breve glosario, preguntas para revisar y reforzar los conocimientos adquiridos, que ayudarán a preparar el estilo de las preguntas del examen.
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Libro de texto para estudiantes de enseñanza secundaria de segundo ciclo que estén preparando el examen CSEC (Caribbean Secondary Education Certificate) en el área de la Biología Humana y la Sociobiología. Contiene los siguientes temas: células, tejidos, órganos y organismos, movimiento de partículas dentro y fuera de las células, fotosíntesis, cadenas y redes alimentarias, flujo de energía y ciclos, nutrición, el sistema respiratorio, el sistema circulatorio, el sistema esquelético, homeostasis, coordinación y control, reproducción, herencia y variación, enfermedad y su impacto en los seres humanos, impacto de las prácticas de salud en el medio ambiente.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Includes "References."
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Includes bibliographical references.
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Mode of access: Internet.
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Mode of access: Internet.
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The high variability in the reproductive biology of stingless bees makes them very amenable for comparative studies with other eusocial bee taxa. We investigated the structural organization of the ovaries of Melipona quadrifasciata queens and workers kept under different social conditions by analyzing their general histology, mitotic activity, and microfilament organization. The overall dynamics of ovarian activity were similar in the two castes, and at emergence their ovarioles contained a previtellogenic follicle. Stingless bees and honey bees differ in the structural organization in the lower germarium, but they have in common synchronized mitotic activity and putative germ line stem cells in the terminal filament. Unlike honey bees, stingless bee workers lay trophic eggs in addition to reproductive eggs. The overall similarities in oogenesis between the two taxa suggest that the decision to form trophic eggs should only occur in the late stages of oogenesis.
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Hepatitis C virus (HCV) infects 170 million people worldwide, and is a major public health problem in Brazil, where over 1% of the population may be infected and where multiple viral genotypes co-circulate. Chronically infected individuals are both the source of transmission to others and are at risk for HCV-related diseases, such as liver cancer and cirrhosis. Before the adoption of anti-HCV control measures in blood banks, this virus was mainly transmitted via blood transfusion. Today, needle sharing among injecting drug users is the most common form of HCV transmission. Of particular importance is that HCV prevalence is growing in non-risk groups. Since there is no vaccine against HCV, it is important to determine the factors that control viral transmission in order to develop more efficient control measures. However, despite the health costs associated with HCV, the factors that determine the spread of virus at the epidemiological scale are often poorly understood. Here, we sequenced partial NS5b gene sequences sampled from blood samples collected from 591 patients in Sao Paulo state, Brazil. We show that different viral genotypes entered Sao Paulo at different times, grew at different rates, and are associated with different age groups and risk behaviors. In particular, subtype 1b is older and grew more slowly than subtypes 1a and 3a, and is associated with multiple age classes. In contrast, subtypes 1a and 3b are associated with younger people infected more recently, possibly with higher rates of sexual transmission. The transmission dynamics of HCV in Sao Paulo therefore vary by subtype and are determined by a combination of age, risk exposure and underlying social network. We conclude that social factors may play a key role in determining the rate and pattern of HCV spread, and should influence future intervention policies.
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The European rabbit (Oryctolagus cuniculus) uses the secretion of the chin gland in the maintenance of social status. Previous work has concentrated on secretion collected directly from the animal. In this study, the analysis was conducted by collecting scent marks made by free-ranging animals. Scent marks were found to be concentrated at the center of the area controlled by a social group, and at the boundaries between two adjacent social groups. Only the mark from dominant animals could be identified. Marks were also collected from the skin of rabbits, where they had been placed by the dominant individual. The mark found on the head of a subordinate animal may, in the future, be used to identify the dominant animal of the social group, who placed the mark.
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The volatile components of the chin gland secretion of the wild European rabbit, Oryctolagus cuniculus (L.), were investigated with the use of gas chromatography. Studies of the chemical nature of this secretion by previous workers demonstrated that it was important in the maintenance of social structure in this species. This study identified 34 different volatile components that consist primarily of aromatic and aliphatic hydrocarbons. Especially common are a series of alkyl-substituted benzene derivatives that provide most of the compound diversity in the secretion. Samples of chin gland secretion collected from animals at three different geographical locations, separated by more than 100 km, showed significant differences in composition. This work suggests that variation among populations needs to be considered when undertaking semiochemical research. Alternate nonparametric methods are also used for the analysis of chromatographic data.