922 resultados para Life table of fertility


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This article discusses inductee music service teachers (to 25 years of age). It explores how their lives, as perceived, shape current identities in teaching and result in several career problems. Respondents were drawn from a comprehensive life history study of 28 Local Education Authority employees. Of this larger cohort, four were age 25 years and below, and the remaining 24 teachers made retrospective comments. Data were collected and analysed between October 2002 and March 2004. Principal findings suggest that schooling failed to address these educators' needs as musical learners; key childhood experiences were external of schools. This often resulted in an idealistic trajectory, in teenage years, towards an occupation as a performer. An occupation in music education was entirely disregarded. Consequently, inductees now consider training experiences an inappropriate platform for their professional lives. Managing group teaching and children's behaviour engenders considerable anxiety. Music service work is also deemed a transient state of affairs. There are implications for training, retention and professional development.

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Although the role of the academic head of department (HoD) has always been important to university management and performance, an increasing significance given to bureaucracy, academic performance and productivity, and government accountability has greatly elevated the importance of this position. Previous research and anecdotal evidence suggests that as academics move into HoD roles, usually with little or no training, they experience a problem of struggling to adequately manage key aspects of their role. It is this problem – and its manifestations – that forms the research focus of this study. Based on the research question, “What are the career trajectories of academics who become HoDs in a selected post-1992 university?” the study aimed to achieve greater understanding of why academics become HoDs, what it is like being a HoD, and how the experience influences their future career plans. The study adopts an interpretive approach, in line with social constructivism. Edited topical life history interviews were undertaken with 17 male and female HoDs, from a range of disciplines, in a post-1992 UK university. These data were analysed using coding, categorisation and theme formation techniques and developing profiles of each of the respondents. The findings from this study suggest that academics who become HoDs not only need the capacity to assume a range of personal and professional identities, but need to regularly adopt and switch between them. Whether individuals can successfully balance and manage these multiple identities, or whether they experience major conflicts and difficulties within or between them, greatly affects their experiences of being a HoD and may influence their subsequent career decisions. It is claimed that the focus, approach and analytical framework - based on the interrelationships between the concepts of socialisation, identity and career trajectory - provide a distinct and original contribution to knowledge in this area. Although the results of this study cannot be generalised, the findings may help other individuals and institutions move towards a firmer understanding of the academic who becomes HoD - in relation to theory, practice and future research.

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Habitat modification for agriculture is one of the greatest current threats to global biodiversity. Studies show large-scale population declines and short-term demographic impacts, but knowledge of the long-term effects of agriculture on individuals remains poor. This thesis examines the short- and long-term impact of agriculture on a reintroduced population of the Mauritius kestrel Falco punctatus, a tropical forest-dwelling raptor endemic to the island of Mauritius, that also utilises agricultural habitats. This population is a particularly appropriate model system, because complete life history data exists for individuals over a 22-year period, alongside detailed habitat and climate data. Agriculture has a short-term detrimental effect on Mauritius kestrel breeding success by exacerbating the seasonal decline in fledgling production. This is partly driven by the habitat-specific composition of the prey community that kestrels exploit to feed their chicks. The fledglings from agricultural territories tend to recruit in agricultural territories. This is largely due to poor natal dispersal and fine-scale spatial autocorrelation in the habitat matrix. Breeders do not respond to agriculture in the breeding territory by dispersing, unless the pair bond is broken. Therefore, individuals originating in agricultural territories tend to recruit, and remain in, agricultural territories throughout their lives. In addition to this, females from agricultural natal territories have shorter lifespans, schedule their peak reproductive output earlier in life, and exhibit more rapid senescence than non-agricultural females. The combination of this long-term effect and the adult experience of agriculture imposed by life history and environmental constraints, leads to a lower mean lifetime reproductive rate compared to females originating in non-agricultural habitats. These results demonstrate that agriculture experienced in early life has a lifelong effect on individuals. The effects can persist in time and space, with potentially delayed effects on population dynamics. These findings are important for understanding species’ responses to agricultural expansion.

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Gracilaria tenuistipitata, a species of commercial interest, is becoming a model organism for studies on red algal physiology and molecular biology as it can be grown easily in vitro under a broad range of conditions. Most of the experiments carried out around the world have been based on a tetrasporophytic clone isolated in our laboratory from a specimen collected in China. Here we describe the life history of this species, give anatomic details of the reproductive structures, illustrate the morphological variability of tetraspore progeny and compare the growth rate of gametophytic and sporophytic thalli. Tetrasporophytic branches showed higher growth rates than gametophytic branches.

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The influence of temperatures on the life parameters of the solitary oothecal parasitoid Evania appendigaster, was investigated in the laboratory. Parasitized oothecae of Periplaneta americana were left to develop under seven constant temperatures: 15, 17, 20, 25, 30, 35, and 40 degrees C. At the end, we found that: (i) E. appendigaster was able to complete development within the temperature range of 17-34 degrees C; (ii) mean adult longevity decreased as temperature increased, with the temperature of 40 degrees C being fatal in a matter of hours; (iii) males lived longer than females between 15 and 30 degrees C; (iv) adult emergence rate was the highest at 25 degrees C, and (v) no wasps emerged at 15 or 40 degrees C. Non-emerged oothecae contained either unhatched eggs or dead larvae. We determined the theoretical lower developmental threshold and thermal constant for the complete development as 12.9 degrees C and 584.8 day-degrees for males, and 13.1 degrees C and 588.2 day-degrees for females, respectively. A good balance between faster development, maximum adult longevity and good egg viability was obtained between 25-30 degrees C, and that would be the best temperature range for rearing E. appendigaster. (C) 2009 Elsevier B.V. All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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O trabalho teve como objetivo conhecer o melhor tipo de mel em relação à longevidade e fertilidade do parasitóide do bicudo-do-algodoeiro Catolaccus grandis. Adultos recém-emergidos foram transferidos para recipientes plásticos de 500mL, adaptados com tubo para fornecer água e umidade para os insetos. Um casal do parasitóide foi mantido em cada recipiente em câmara climatizada a 25±1°C, UR = 70±10% e fotoperíodo de 14h. O trabalho constou de 4 tratamentos: mel de flor de laranjeira; mel de flores de plantas silvestres; mel de cana-de-açúcar (todos produzidos por Apis mellifera) e mel de flores silvestres produzido por abelha Jataí (Tetragonistica angustula), com 15 repetições cada. Adultos recém-emergidos do parasitóide receberam cinco larvas de Euscepes postfasciatus encapsuladas em parafilm. Três gotículas de mel foram colocadas sobre o parafilm. Calculou-se a longevidade de machos e fêmeas, número de ovos dia-1 fêmea-1 e número total de ovos fêmea-1 e construíram-se as tabelas de fertilidade. As melhores dietas para alimentar adultos de C. grandis foram o mel silvestre e o de laranjeira. A melhor fecundidade foi observada na dieta de mel de laranjeira (101,60 ovos fêmea-1) e os melhores resultados para aumento reprodutivo e populacional deste parasitóide foram obtidos com mel de laranja e com mel silvestre.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The Dufour's gland is found closely associated with the sting apparatus of all female hymenopterans, playing multiple roles among bees. In some species of Bombus the gland may be involved in production of nestmate recognition pheromones, but in B. terrestris its function is not certain yet. The morphology of the :Dufour's gland of B. terrestris queens and the ultrastructural features of its cells were studied in different ages and behavioural stages using routine transmission electron microscopy. Measurements of the length and the diameter of the gland in the same conditions were also made. The Dufour's gland of the queen increases significantly in size (both in length and in diameter) with age and reproductive activity the ultrastructural features of the gland show electrondense material that comes from the haemolymph. This material is also present in the intercellular spaces, and is conducted to the subcuticular space, to be released directly into the glandular lumen. Hence at least part of the secretion is probably taken up directly from the haemolymph. The ultrastructural features indicate a more active phase of the gland corresponding to the period of egg-laying of the queen, and a decrease in activity when the queen is in hibernation as well as after the competition point. In conclusion, the gland is probably involved in reproduction, more specifically, in the marking off eggs.