918 resultados para global changes


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Observational studies have reported solar magnetic modulation of terrestrial lightning on a range of time scales, from days to decades. The proposed mechanism is two-step: lightning rates vary with galactic cosmic ray (GCR) flux incident on Earth, either via changes in atmospheric conductivity and/or direct triggering of lightning. GCR flux is, in turn, primarily controlled by the heliospheric magnetic field (HMF) intensity. Consequently, global changes in lightning rates are expected. This study instead considers HMF polarity, which doesnʼt greatly affect total GCR flux. Opposing HMF polarities are, however, associated with a 40â60% difference in observed UK lightning and thunder rates. As HMF polarity skews the terrestrial magnetosphere from its nominal position, this perturbs local ionospheric potential at high latitudes and local exposure to energetic charged particles from the magnetosphere. We speculate as to the mechanism(s) by which this may, in turn, redistribute the global location and/or intensity of thunderstorm activity.

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Data collected by ground magnetometers and high latitude radars during a small isolated substorm are discussed in terms of the global changes in convection during the substorm. This substorm was observed during the international GISMOS (Global Ionospheric Simultaneous Measurements of Substorms) Experiment of 1 â 5 June 1987 and the array of observations discussed here span the night sector from approximately dusk to dawn. The substorm, observed by the Sondrestrom radar and auroral and midlatitude magnetometers is associated with a polar cap contraction observed near dusk by the EISCAT radar.

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The attribute focus in engineering education now adopted by the engineering education accrediting bodies of the US, UK and Australia is based on meeting the assumed needs of professional practice. It is associated with an increasing expectation by employers of work-ready graduates rather than relying on subsequent work-based learning and experience to develop many of the essential professional practice attributes. Yet the scope of the mechanical engineering profession is broad and views of practitioners contributing to debate on attribute requirements are largely influenced by their own often unique professional formation.<br /><br />In addition, the formative development of the profession in Australia has been significantly influenced by 19th and 20th century UK and US practices, although historically the industrial profile of Australia has been strikingly different. An analysis of current industry distribution of Australian, UK and US mechanical engineers presented in this paper shows continuing, although less marked, differences.<br /><br />To develop a clearer perception of the profession in Australia, its educational formation, and operational environment, this paper provides a concise study of the formative development of the profession, and presents a breakdown of the industry sectors in which they are currently employed. The effects of momentous global changes in engineering employment and formation over recent decades are also discussed.<br /><br />Recent changes in engineering employment have included major structural changes to organisations, accelerating technical and educational developments and mounting societal expectations making it imperative that attributes be attuned to the new engineering paradigm as increasing demands are placed on our graduates.<br /><br />This paper provides an essential foundation for ongoing debate and analysis of attribute needs related to this broadly based engineering discipline. Although presented from an Australian perspective, many issues discussed are applicable worldwide.<br />

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This study has utilised comparative functional genomics to exploit animal models with extreme adaptation to lactation to identify candidate genes that specifically regulate protein synthesis in the cow mammary gland. Increasing milk protein production is valuable to the dairy industry. The lactation strategies of both the Cape fur seal (<i>Artocephalus pusillus pusillus</i>) and the tammar wallaby (<i>Macropus eugenii</i>) include periods of high rates of milk protein synthesis during an established lactation and therefore offer unique models to target genes that specifically regulate milk protein synthesis. Global changes in mammary gene expression in the Cape fur seal, tammar wallaby, and the cow (<i>Bos taurus</i>) were assessed using microarray analysis. The folate receptor &alpha; (FOLR1) showed the greatest change in gene expression in all three species [cow 12.7-fold (<i>n</i> = 3), fur seal 15.4-fold (<i>n</i> = 1), tammar 2.4-fold (<i>n </i>= 4)] at periods of increased milk protein production. This compliments previous reports that folate is important for milk protein synthesis and suggests FOLR1 may be a key regulatory point of folate metabolism for milk protein synthesis within mammary epithelial cells (lactocytes). These data may have important implications for the dairy industry to develop strategies to increase milk protein production in cows. This study illustrates the potential of comparative genomics to target genes of interest to the scientific community. <br />

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Murine milk protein gene expression requires insulin, hydrocortisone, and prolactin; however, the role of insulin is not well understood. This study, therefore, examined the requirement of insulin for milk protein synthesis. Mammary explants were cultured in various combinations of the lactogenic hormones and global changes in gene expression analysed using Affymetrix microarray. The expression of 164 genes was responsive to insulin, and 18 were involved in protein synthesis at the level of transcription and posttranscription, as well as amino acid uptake and metabolism. The folate receptor gene was increased by fivefold, highlighting a potentially important role for the hormone in folate metabolism, a process that is emerging to be central for protein synthesis. Interestingly, gene expression of two milk protein transcription factors, Stat5a and Elf5, previously identified as key components of prolactin signalling, both showed an essential requirement for insulin. Subsequent experiments in HCll cells confirmed that Stat5a and Elf5 gene expression could be induced in the absence of prolactin but in the presence of insulin. Whereas prolactin plays an essential role in phosphorylating and activating Stat5a, gene expression is only induced when insulin is present. This indicates insulin plays a crucial role in the transcription of the milk protein genes.

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The overwhelming weight of academic historical writing on Association football in Australia since the 1970s has focused on the game through the prism of ethnicity. The ills of the game and its failure to become the dominant code of football, as it is in many countries, are regularly attributed to the many ways in which the game was or could be portrayed as a foreign import that brought non-Australian concerns onto the sporting field where they had no place. Here it is argued that structural issues have a much greater role to play in understanding the evolution of the game since the 1950s. Global changes in sport and Association football in particular have also impinged significantly on the game in Australia. Now football is a major part of the Australian sporting landscape, though its position vis-a`-vis rival codes remains contested.<br />

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Urbanization is one of the most evident global changes. Research in the field of urban growth modelling has generated models that explore for drivers and components of the urban growth dynamics. Cellular automata (CA) modeling is one of the recent advances, and a number of CA-based models of urban growth have produced satisfactory simulations of spatial urban expansion over time. Most application and test of CA-based models of urban growth which provide likely and reliable simulations has been developed in urban regions of developed nations; urban regions in the United States, in particular. This is because most of the models were developed in universities and research centers of developed nations, and these regions have the required data, which is extensive. Most of the population growth in the world, however, occurs in the developing world. While some European countries show signs of stabilization of their population, in less developed countries, such as India, population still grows exponentially. And this growth is normally uncoordinated, which results in serious environmental and social problems in urban areas. Therefore, the use of existing dynamic&ndash;spatial models of urban growth in regions of developing nations could be a means to assist planners and decision makers of these regions to understand and simulate the process of urban growth and test the results of different development strategies. The pattern of growth of urban regions of developing nations, however, seems to be different of the pattern of developed countries. The former use to be more dense and centralized, normally expanding outwards from consolidated urban areas; while the second is normally more fragmented and sparse. The present paper aims to investigate to how extent existing CA-based urban growth models tested in developed nations can also be applied to a developing country urban area. The urban growth model was applied to Porto Alegre City, Brazil. An expected contiguous expansion from existing urban areas has been obtained as following the historical trends of growth of the region. Moreover, the model was sensitive and able to portray different pattern of growth in the study area by changing the value of its parameters.<br />

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Background elimination models are widely used in motion tracking systems. Our aim is to develop a system that performs reliably under adverse lighting conditions. In particular, this includes indoor scenes lit partly or entirely by diffuse natural light. We present a modified &quot;median value&quot; model in which the detection threshold adapts to global changes in illumination. The responses of several models are compared, demonstrating the effectiveness of the new model.

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This research has the objective of analyze the possibilities offered by the use of the graphology in the process of personnel's selection that aim at the completion of current vacancies of job offers. The study is based in the verification of the applicability and forms of use of selection instruments of personal, mainly of those developed with objective of identifying the aptitudes and the characteristics of the individual's personality. Analyzing its applicability, as form of adapting to the reality today, the graphology, besides assisting to the new variables that the global changes impose to the individuals' behavior and his relationship with the companies, appears as alternative and it is occupying, every day, more space in the professional evaluation area. This study offers reasons so that one can consider the graphology analysis as one more instrument to be used in personnel's selection, in agreement with the possibilities and identified limitations, when used for that end. Tends as objective to explain the reasons of the use of the graphology analysis as evaluation tool, the exploratory and explanatory researches were adopted. This explanation will appear, then, of the verification and analysis of the data obtained in the bibliographical and of field researches, which allows like this to base its report, development and applicability.

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Depth-integrated primary productivity (PP) estimates obtained from satellite ocean color-based models (SatPPMs) and those generated from biogeochemical ocean general circulation models (BCGCMs) represent a key resource for biogeochemical and ecological studies at global as well as regional scales. Calibration and validation of these PP models are not straightforward, however, and comparative studies show large differences between model estimates. The goal of this paper is to compare PP estimates obtained from 30 different models (21 SatPPMs and 9 BOGCMs) to a tropical Pacific PP database consisting of similar to 1000 C-14 measurements spanning more than a decade (1983-1996). Primary findings include: skill varied significantly between models, but performance was not a function of model complexity or type (i.e. SatPPM vs. BOGCM); nearly all models underestimated the observed variance of PR specifically yielding too few low PP (< 0.2 g Cm-2 d(-1)) values; more than half of the total root-mean-squared model-data differences associated with the satellite-based PP models might be accounted for by uncertainties in the input variables and/or the PP data; and the tropical Pacific database captures a broad scale shift from low biomassnormalized productivity in the 1980s to higher biomass-normalized productivity in the 1990s, which was not successfully captured by any of the models. This latter result suggests that interdecadal and global changes will be a significant challenge for both SatPPMs and BOGCMs. Finally, average root-mean-squared differences between in situ PP data on the equator at 140 degrees W and PP estimates from the satellite-based productivity models were 58% lower than analogous values computed in a previous PP model comparison 6 years ago. The success of these types of comparison exercises is illustrated by the continual modification and improvement of the participating models and the resulting increase in model skill. (C) 2008 Elsevier BY. All rights reserved.

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Includes bibliography

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Evidencia a análise do percurso institucional e geoestratégico do Projeto Calha Norte (PCN) como processo de territorialização da fronteira política. O PCN foi pensado nos moldes convencionais da defesa e influenciado pela Doutrina de Segurança Nacional (DSN) dos anos sessenta e setenta, que objetivava e objetiva garantir o aumento da presença do Estado na Faixa de Fronteira Norte (Arco Norte), contribuindo para a Defesa Nacional e para a assistência às populações locais. Busca entender as implicações históricas, estratégicas, geopolíticas, financeiras e ambientais, desde a sua origem até os anos noventa com ênfase no governo de Fernando H. Cardoso - FHC (1994-2002). Apresenta a idéia de que a política de defesa implementada por este obedeceu às inflexões das mudanças internas na governança brasileira, bem como almejou adequá-la às transformações em curso regional e mundialmente, caracterizadas pela substituição da ordem bipolar para multipolar/unipolar, alteração no perfil das instituições políticas e, sobretudo, da integração hemisférica do país num quadro de incertezas e apelo ao fortalecimento da segurança coletiva. Essas mudanças ocorreram no contexto da modernização capitalista, na qual o PCN é concebido como uma modalidade particular de intervenção e expansão do Estado, que tem o uso exclusivo do monopólio da força, cumprindo suas prerrogativas constitucionais numa área marrom - ausência do Estado enquanto um conjunto de burocracias funcionando efetivamente numa área de baixa densidade demográfica. A ineficácia dessas dimensões do Estado define a peculiaridade do circuito da ilegalidade, isto é, o locus das atividades ilícitas tais como o narcotráfico e o contrabando. Assim, a racionalidade presente na ação do Estado consiste em articular os elementos capazes de estimular a materialização de um processo de homogeneização do espaço social na fronteira política em contexto de integração e cooperação com os países da Pan-Amazônia. Baseando-se em indicadores demográficos, econômico-financeiros e ambientais, e numa ampla base de dados sobre a Faixa de Fronteira Norte, a pesquisa concluiu pela necessidade da intervenção na fronteira política, onde o Estado busca cumprir, relativamente, sua função para ordenar e disciplinar as relações e os processos sociais a partir de referências constitucionais; afirmou que o esvaziamento financeiro deveu-se menos ao programa governamental para ajustar as contas públicas e o pagamento da dívida externa do que à decisão política de reorientar os investimentos para o Projeto; provou-se que há um movimento para a inclusão efetiva da sustentabilidade na nova PDN (Política de Defesa Nacional) e; finalmente, argumentou-se a favor da necessidade de integrar o PCN ao sistema de produção de informações do SIVAM entendido como um novo enfoque sobre a defesa nacional na Era da Informação, e que é necessário para a vigilância da região.