971 resultados para Agro-pastoral eco-tone


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Foot-and-mouth disease (FMD), a disease of cloven hooved animals caused by FMD virus (FMDV), is one of the most economically devastating diseases of livestock worldwide. The global burden of disease is borne largely by livestock-keepers in areas of Africa and Asia where the disease is endemic and where many people rely on livestock for their livelihoods and food-security. Yet, there are many gaps in our knowledge of the drivers of FMDV circulation in these settings. In East Africa, FMD epidemiology is complicated by the circulation of multiple FMDV serotypes (distinct antigenic variants) and by the presence of large populations of susceptible wildlife and domestic livestock. The African buffalo (Syncerus caffer) is the only wildlife species with consistent evidence of high levels of FMDV infection, and East Africa contains the largest population of this species globally. To inform FMD control in this region, key questions relate to heterogeneities in FMD prevalence and impacts in different livestock management systems and to the role of wildlife as a potential source of FMDV for livestock. To develop FMD control strategies and make best use of vaccine control options, serotype-specific patterns of circulation need to be characterised. In this study, the impacts and epidemiology of FMD were investigated across a range of traditional livestock-keeping systems in northern Tanzania, including pastoralist, agro-pastoralist and rural smallholder systems. Data were generated through field studies and laboratory analyses between 2010 and 2015. The study involved analysis of existing household survey data and generated serological data from cross-sectional livestock and buffalo samples and longitudinal cattle samples. Serological analyses included non-structural protein ELISAs, serotype-specific solid-phase competitive ELISAs, with optimisation to detect East African FMDV variants, and virus neutralisation testing. Risk factors for FMDV infection and outbreaks were investigated through analysis of cross-sectional serological data in conjunction with a case-control outbreak analysis. A novel Bayesian modeling approach was developed to infer serotype-specific infection history from serological data, and combined with virus isolation data from FMD outbreaks to characterise temporal and spatial patterns of serotype-specific infection. A high seroprevalence of FMD was detected in both northern Tanzanian livestock (69%, [66.5 - 71.4%] in cattle and 48.5%, [45.7-51.3%] in small ruminants) and in buffalo (80.9%, [74.7-86.1%]). Four different serotypes of FMDV (A, O, SAT1 and SAT2) were isolated from livestock. Up to three outbreaks per year were reported by households and active surveillance highlighted up to four serial outbreaks in the same herds within three years. Agro-pastoral and pastoral livestock keepers reported more frequent FMD outbreaks compared to smallholders. Households in all three management systems reported that FMD outbreaks caused significant impacts on milk production and sales, and on animals’ draught power, hence on crop production, with implications for food security and livelihoods. Risk factor analyses showed that older livestock were more likely to be seropositive for FMD (Odds Ratio [OR] 1.4 [1.4-1.5] per extra year) and that cattle (OR 3.3 [2.7-4.0]) were more likely than sheep and goats to be seropositive. Livestock managed by agro-pastoralists (OR 8.1 [2.8-23.6]) or pastoralists (OR 7.1 [2.9-17.6]) were more likely to be seropositive compared to those managed by smallholders. Larger herds (OR: 1.02 [1.01-1.03] per extra bovine) and those that recently acquired new livestock (OR: 5.57 [1.01 – 30.91]) had increased odds of suffering an FMD outbreak. Measures of potential contact with buffalo or with other FMD susceptible wildlife did not increase the likelihood of FMD in livestock in either the cross-sectional serological analysis or case-control outbreak analysis. The Bayesian model was validated to correctly infer from ELISA data the most recent serotype to infect cattle. Consistent with the lack of risk factors related to wildlife contact, temporal and spatial patterns of exposure to specific FMDV serotypes were not tightly linked in cattle and buffalo. In cattle, four serial waves of different FMDV serotypes that swept through southern Kenyan and northern Tanzanian livestock populations over a four-year period dominated infection patterns. In contrast, only two serotypes (SAT1 and SAT2) dominated in buffalo populations. Key conclusions are that FMD has a substantial impact in traditional livestock systems in East Africa. Wildlife does not currently appear to act as an important source of FMDV for East African livestock, and control efforts in the region should initially focus on livestock management and vaccination strategies. A novel modeling approach greatly facilitated the interpretation of serological data and may be a potent epidemiological tool in the African setting. There was a clear temporal pattern of FMDV antigenic dominance across northern Tanzania and southern Kenya. Longer-term research to investigate whether serotype-specific FMDV sweeps are truly predictable, and to shed light on FMD post-infection immunity in animals exposed to serial FMD infections is warranted.

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This thesis concerns the analysis of the socio-economic transformation of communities in Bronze Age southwestern Cyprus. Through the adoption of a dialectical perspective of analysis, individuals and environment are considered part of the same unity: they are cooperating agents in shaping society and culture. The Bronze Age is a period of intense transformation in the organization of local communities, made of a continuous renegotiation of the socio-economic roles and interactions. The archaeological record from this portion of the island allows one to go beyond the investigation of the complex and articulated transition from the EBA-MBA agro-pastoral and self-sufficient communities to the LBA centralized and trade-oriented urban-centres. Through a shifting of analytical scales, the emerging picture suggests major transformations in the individual-community-territory dialectical relations. A profound change in the materials conditions of social life, as well as in the superstructural realm, was particularly entailed by the dissolution of the relation to the earth, due to the emergence of new forms of land exploitation/ownership and to the shift of the settlement pattern in previously unknown areas. One of the key points of this thesis is the methodological challenge of working with legacy survey data as I re-analysed a diverse archaeological legacy, which is the result of more than fifty years of survey projects, rescue and research-oriented excavations, as well as casual discoveries. Source critique and data evaluation are essential requirements in an integrative and cross-disciplinary regional perspective, in the comprehensive processing of heterogeneous archaeological and environmental datasets. Through the estimation of data precision and certainty, I developed an effective - but simple - method to critically evaluate existing datasets and to inter-correlate them without losing their original complexity. This powerful method for data integration can be applied to similar datasets belonging to other regions and other periods as it originates from the evaluation of larger methodological and theoretical issues that are not limited to my spatial and temporal focus. As I argue in this thesis, diverse archaeological legacies can be efficiently re-analysed through an integrative and regional methodology. The adoption of a regional scale of analysis can provide an excellent perspective on the complexity of transformations in ancient societies, thus creating a fundamental bridge between the local stories and grand landscape narratives.

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Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Ciência e Sistemas de Informação Geográfica

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Nos últimos 30 anos, a problemática ambiental tem se apresentado, para a espécie humana, como um importante espaço de discussão acerca de novos valores éticos, políticos e existenciais regulatórios da vida individual e coletiva na biosfera terrestre. Em um primeiro momento, este recente despertar global para a temática do meio ambiente parece estar associado à exacerbação dos “problemas” (agora tidos como planetários) a ele vinculado. Contudo, por trás deste aparente jogo de causa-efeito, escondem-se motivações muito mais profundas e que são, de fato, aquelas que levaram a sociedade contemporânea a identificar conscientemente tais “problemas”. Este processo está intimamente relacionado à própria historicidade que envolve a construção social de uma problemática que, apesar de parecer inédita, é antiga e recorrente na história da humanidade. Além disso, as conseqüências desse aparente “despertar” não podem ser medidas somente em relação ao que representam em termos de eventuais avanços nas políticas de preservação ou, da mesma forma, quanto à capacidade de responder adequadamente aos chamados “novos riscos globais”. Exemplo disso é o fato de que, por trás destes macroprocessos ecológicos, estão em curso certas derivações não programadas relacionadas às populações e realidades locais e regionais. Neste sentido, os grupos sociais que vivem no que se costuma chamar de “meio rural” (expressão que, neste trabalho, insere-se dentro do conceito de agro-eco-sistema) não necessariamente irão aderir completamente as políticas ambientais pensadas pelos planejadores dos órgãos públicos, das instituições de pesquisa ou, ainda, das organizações não-governamentais. Em suma, existe aí uma “apropriação criativa” e que não pode ser facilmente medida ou antecipada Será justamente a reflexão sobre como está se dando este processo de interferência da problemática ambiental nos agro-eco-sistemas o objeto desta dissertação. Para tanto, optou-se, primeiro, por escolher um determinado espaço social e geográfico (o agro-eco-sistema da bacia do Rio Maquiné) para realizar as análises empíricas e, segundo, tomar como base analítica os pontos de vista de dois grupos sociais distintos: os agricultores familiares e seus mediadores sociais. Assim, pôde-se constatar que, nestes espaços, a problemática ambiental tem proporcionado, efetivamente, o desencadeamento de novos processos de reestruturação das relações homem-meio ambiente. Contudo, por outro lado, pôde-se, igualmente, perceber que este fenômeno possui um caráter paradoxal. Isto, porque há, neste caso, a imposição de uma série de novas normas legais, padrões produtivos e valores morais antes inexistentes e que agora tem que ser incorporadas pelas populações locais. Ao longo da pesquisa, feita segundo uma perspectiva ao mesmo tempo histórica e espacial, várias contradições que se seguiram à chegada dos novos “valores ecológicos” puderam ser identificadas. Neste sentido, um dos resultados mais interessantes foi perceber que (pelo menos no agro-eco-sistema estudado), tal como foram os processos envolvendo a chamada “modernização conservadora” da agricultura, também a introdução de políticas ambientais se mostrou amplamente desigual (no que diz respeito à diversidade social destes espaços e as oportunidades disponíveis aos agentes), desestruturante (principalmente no que tange aos modos de vida existentes) e pouco “democrática” (havendo uma completa desconsideração dos conhecimentos e experiências dos agricultores em relação ao ambiente onde eles próprios vivem, trabalham, se divertem e, obviamente, retiram aquilo que garante sua reprodução social ao longo do tempo).

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En Guasca, Cundinamarca, se han configurado cambios profundos en el uso de los recursos naturales y el trabajo. En la misma área donde operó una mina de cal a cielo abierto por más de sesenta años, hoy en día existe una reserva biológica. Este proceso ha conllevado transformaciones y negociaciones entre las formas locales de uso de los recursos naturales y los usos propuestos por la conservación ambiental. Por su parte, el trabajo en la vereda se ha visto afectado por el cambio reciente en el usufructo de los recursos ambientales y las precariedades económicas del agro en Colombia. El argumento central de este texto es que la declaratoria de áreas protegidas privadas, como práctica suscrita al discurso ambientalista global, más que un proceso neutro, es una fuente de tensión constante entre pobladores locales y administradores de las zonas de conservación ecológica por cuenta del manejo territorial y ambiental, el entendimiento del uso de los recursos naturales y la naturaleza, la propiedad, el empleo y la descentralización del poder estatal. Así las cosas, este trabajo se preocupa por analizar las tensiones e implicaciones que supone la declaratoria de áreas protegidas para las poblaciones locales, en particular en su economía, trabajo y formas de apropiarse de la naturaleza y sus recursos.

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Le Niger est un pays sahélien situé au sud du Sahara en Afrique de l’ouest. Il couvre une superficie de 1267 000 km2 dont les 2 / 3 sont désertiques, il est limité au Nord par l’Algérie et la Libye, au Sud par le Nigeria et le Bénin, à l’Est par le Tchad et à l’Ouest par le Mali et le Burkina faso. Le climat est caractérisé par trois saisons : saison froide (novembre – février), saison chaude (mars – mai) et une saison pluvieuse (juin –septembre.) Les précipitations varient du Nord au Sud avec un isomètre évoluant respectivement de 5O mm à 800 mm sur une période de un à trois mois. Cette irrégularité des précipitations influe grandement sur la production agricole dans un pays essentiellement à vocation agro-pastorale. Sa population est estimée à 12 000 000 d’habitants environ selon le Recensement Administratif 2004 est composée de 9 ethnies réparties dans les huit régions du pays.

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Silvo-pastoral are mixed systems of trees and grass, which have been proposed as a means to extend the benefits of forest to farmed land. Agro-forestry systems under semi-arid Mediterranean conditions, called montados in Portugal and dehesas in Spain, cover substantial areas in the world. These silvo-pastoral systems are the most extensive European agro-forestry system, as they cover 3.5–4.0 Mha in Spain and Portugal. Long-term studies are essential to assess the magnitude of the temporal nutrient flow dynamics in terrestrial ecosystems and to understand the response of these systems to fertilizer management. In order to implement the conservation task and recovery of resources through silvo-pastoral systems it is necessary to know and correct potential limiting factors, especially the soil factor, and this requires agronomic knowledge as well as the implmentation of the available new technologies. In this context, this task aims at a better understanding of the contribution of the two components of montado ecosystem (trees and herbaceous vegetation) on the soil nutrient and water dynamics, that allow for the interpretation of the variability of pasture dry matter yield and help the farmer in the management of tree density. Collaterally the task will evaluate and calibrate new technologies that simplify the monitoring of soil, grassland, trees and grazing animals.

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In this study, we evaluated the expression of the Zenk protein within the nucleus taeniae of the pigeon’s amygdala (TnA) after training in a classical aversive conditioning, in order to improve our understanding of its functional role in birds. Thirty-two 18-month-old adult male pigeons (Columba livia), weighing on average 350 g, were trained under different conditions: with tone-shock associations (experimental group; EG); with shock-alone presentations (shock group; SG); with tone-alone presentations (tone group; TG); with exposure to the training chamber without stimulation (context group; CG), and with daily handling (naive group; NG). The number of immunoreactive nuclei was counted in the whole TnA region and is reported as density of Zenk-positive nuclei. This density of Zenk-positive cells in the TnA was significantly greater for the EG, SG and TG than for the CG and NG (P < 0.05). The data indicate an expression of Zenk in the TnA that was driven by experience, supporting the role of this brain area as a critical element for neural processing of aversive stimuli as well as meaningful novel stimuli.

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The aim of this study was to investigate the possible effects of reproductive experience on dopaminergic profile in three different brain tissues, hypothalamus, striatum and cortex in rats on 7th-8th day of pregnancy during the light-dark shift (between 1700-1900h). Results showed that in hypothalamus, dopamine levels increased and DOPAC/DA decreased as a function of parity. In cortex, no differences were observed. In striata, the haloperidol-induced HVA and HVA/DA increases were less intense in experienced animals. These findings suggested that reproductive experience produced functional central changes during pregnancy, with different neurochemical responses depending on the brain region.

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The effects of alkaline treatments of the wheat straw with sodium hydroxide were investigated. The optimal condition for extraction of hemicelluloses was found to be with 0.50 mol/l sodium hydroxide at 55C for 2 h. This resulted in the release of 17.3% of hemicellulose (% dry starting material), corresponding to the dissolution of 49.3% of the original hemicellulose. The yields were determined by gravimetric analysis and expressed as a proportion of the starting material. Chemical composition and physico-chemical properties of the samples of hemicelluloses were elucidated by a combination of sugar analyses, Fourier transform infrared (FTIR), and thermal analysis. The results showed that the treatments were very effective on the extraction of hemicelluloses from wheat straw and that the extraction intensity (expressed in terms of alkali concentration) had a great influence on the yield and chemical features of the hemicelluloses. The FTIR analysis revealed typical signal pattern for the hemicellulosic fraction in the 1,200-1,000 cm(-1) region. Bands between 1,166 and 1,000 cm(-1) are typical of xylans.

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At present, the cement industry generates approximately 5% of the world`s anthropogenic CO(2) emissions. This share is expected to increase since demand for cement based products is forecast to multiply by a factor of 2.5 within the next 40 years and the traditional strategies to mitigate emissions, focused on the production of cement, will not be capable of compensating such growth. Therefore, additional mitigation strategies are needed, including an increase in the efficiency of cement use. This paper proposes indicators for measuring cement use efficiency, presents a benchmark based on literature data and discusses potential gains in efficiency. The binder intensity (bi) index measures the amount of binder (kg m(-3)) necessary to deliver 1 MPa of mechanical strength, and consequently express the efficiency of using binder materials. The CO(2) intensity index (ci) allows estimating the global warming potential of concrete formulations. Research benchmarks show that bi similar to 5 kg m(-3) MPa(-1) are feasible and have already been achieved for concretes >50 MPa. However, concretes with lower compressive strengths have binder intensities varying between 10 and 20 kg m(-3) MPa(-1). These values can be a result of the minimum cement content established in many standards and reveal a significant potential for performance gains. In addition, combinations of low bi and ci are shown to be feasible. (c) 2010 Elsevier Ltd. All rights reserved.

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This study examined the test performance of distortion product otoacoustic emissions (DPOAEs) when used as a screening tool in the school setting. A total of 1003 children (mean age 6.2 years, SD = 0.4) were tested with pure-tone screening, tympanometry, and DPOAE assessment. Optimal DPOAE test performance was determined in comparison with pure-tone screening results using clinical decision analysis. The results showed hit rates of 0.86, 0.89, and 0.90, and false alarm rates of 0.52, 0.19, and 0.22 for criterion signal-to-noise ratio (SNR) values of 4, 5, and 11 dB at 1.1, 1.9, and 3.8 kHz respectively. DPOAE test performance was compromised at 1.1 kHz. In view of the different test performance characteristics across the frequencies, the use of a fixed SNR as a pass criterion for all frequencies in DPOAE assessments is not recommended. When compared to pure tone plus tympanometry results, the DPOAEs showed deterioration in test performance, suggesting that the use of DPOAEs alone might miss children with subtle middle ear dysfunction. However, when the results of a test protocol, which incorporates both DPOAEs and tympanometry, were used in comparison with the gold standard of pure-tone screening plus tympanometry, test performance was enhanced. In view of its high performance, the use of a protocol that includes both DPOAEs and tympanometry holds promise as a useful tool in the hearing screening of schoolchildren, including difficult-to-test children.

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In this paper we take advantage of the segmental control afforded by full and partial Vietnamese reduplication on a constant carrier phrase to obtain acoustic evidence of assymetrical prominence relations (van der Hulst 2005), in support of a hypothesis that Vietnamese reduplications are phonetically right headed and that tone sandhi is a reduction phenomenon occurring on prosodically weak positions (Shih 2005). Acoustic parameters of syllable duration (onset, nucleus and coda), F0 range, F0 contour, vowel intensity, spectral tilt and vowel formant structure are analyzed to determine: (1) which syllable of the two (base or reduplicant) is more prominent and (2) how the tone sandhi forms differ from their full reduplicated counterparts. Comparison of full and partial reduplicant syllables in tone sandhi forms provide additional support for this analysis.

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