Preocupações com o envelhecimento populacional, que cresce rapidamente nos países em desenvolvimento, aliado à intensa degradação do meio ambiente, levaram ao delineamento desta pesquisa. Inicialmente, procurou-se discutir e compreender o processo de envelhecimento individual e populacional, estudando suas teorias: por que e como envelhecemos e alcançamos a longevidade. Destaca-se os fatores associados positivamente à longevidade: restrição alimentar, genética e hereditariedade, hábitos de vida, engajamento social, entre outros. E condicionantes negativos, situações de exposição opostas a estas, dentre as quais a poluição merece destaque pela morbimortalidade a ela associada, podendo encurtar o tempo de vida. Destaca-se a complexidade dos problemas ambientais e a necessidade de romper com o reducionismo, avançando na Saúde Ambiental e seus indicadores. O objetivo do presente estudo foi compreender as possíveis associações entre fatores ambientais e aumento da longevidade humana, segundo a perspectiva de um grupo de longevos ferroviários. Questionário semi-estruturado foi aplicado a uma população mais homogênea de longevos (30 ex-ferroviários aposentados da Estrada de Ferro Sorocabana de Botucatu). Caracterizou-se a vida desses indivíduos e se resgatou a importante história da ferrovia, buscando evidências de associações entre meio ambiente, saúde e longevidade, por intermédio de metodologia qualitativa (Grounded Theory) e quantitativa. Utilizando a Grounded Theory, emergiram três fenômenos, retratados a partir da experiência dos entrevistados: ANIQUILANDO A VIDA, GERANDO VIDA e FALTANDO CONTROLE SOCIAL E DO ESTADO. Esses longevos percebem o aniquilamento atual do meio ambiente, da ferrovia e até da própria vida, desencadeado pela falta de controle social e do Estado, aliado à falta de consciência coletiva, empreendido pelo movimento da ideologia capitalista do lucro a qualquer custo. Percebem que vários fatores influenciam a longevidade, como: conviver em um ambiente harmônico e sem poluição; adotar estilo de vida saudável e sociável; envolver-se com o trabalho e ter renda para se sustentar; ser e estar tranqüilo e feliz; fatores biológicos e genéticos favoráveis. Por meio desta pesquisa, levantam-se três premissas: a complexidade dos fatores associados ao binômio meio-ambiente-longevidade, suas inter-relações, e a necessidade de internalização do meio ambiente no processo de saúde-doença-envelhecimento. Propõem-se nova hipótese nas teorias da longevidade: valorização das funções desempenhadas(VFD). A partir da experiência dos longevos, destacando o papel da memória, denota-se a importância em subsidiar a população idosa a empoderar-se para que possa exigir dos governantes ações mais efetivas no sentido de garantir melhor qualidade de vida. Também é importante empoderá-los para que possam lutar contra a degradação ambiental e da própria vida, contra esta cultura do imediatismo e da etnodesvalorização, em um processo dialético histórico que faz o passado representar a vida (ganhos = trabalho, tempo áureo da ferrovia) e o presente a morte (perdas = degradação ambiental, aniquilamento da ferrovia e ferroviários, doenças). / Concerns with population aging, which grows fast in developing countries, associated with the intense environmental degradation, have led to delineation this research. Initially tried to discuss, and understand individual and population aging process, studying their theories: how and why we age, and reach longevity. Emphasize the factors positively associated to longevity: food restriction, genetics, and heredity, life habits, social engagement, among others. And negative conditioners, situation of exposure opposite to these, especially highlighting pollution because of the morbimortality associated with it, can shorten the life-span. Complexity of environmental problems, and necessity to break up reductionism are outstanding, moving forward in Environmental Health and its indicators. The objective of the current study aim to comprehend the possibility of associating environmental factors with an increase in human longevity, through the perspective of a group of longevity railroaders. A semi-structured questionnaire was applied to a homogeneous longevity group (30 retired ex-railroaders from Estrada de Ferro Sorocabana in Botucatu, State of São Paulo). It characterized the lives of these individuals and recovered the importance of railroad history, seeking evidences of associations among environment, health, and longevity through qualitative methodology (Grounded Theory) and quantitative one. Through Grounded Theory, three phenomena emerged, depicted from the experience of the interviewed people: ANNIHILATING LIFE, GENERATING LIFE, and LACKING SOCIAL, AND STATE CONTROL. These longevity individuals detect the current annihilation of the environment, of the railroad, and even of life itself, descending from the lack of social, and State control, allied with lack of a collective conscience, undertaken by the movement of capitalist ideology of profit at any cost. They perceive that various factors have an influence on longevity, such as living in a harmonious environment without pollution, adopting a healthful and sociable lifestyle, involving oneself in work that earns a sustainable income, becoming and staying tranquil and happy; having favorable biological and genetic factors. This research raises three premises: the complexity of factors associated to the binomial environment longevity; their interrelations; and the need to internalize environment in the health-disease-aging process. Suggest a new hypothesis of theory of longevity: Valorization of the Develop Functions (VDF). From the experience of longevity workers, emphasizing memorys role, it denotes the importance of providing the elderly population and empowering them for what they may demand from more effective governmental actions in the sense of guaranteeing a better quality of life. Also it is important to empower them for their struggle against degradation of the environment and own lives, against this culture of immediatism, and ethno devaluation, in a historic dialetic process which makes the past represent life (profits=work, golden age of the railroads) and the present signify death (losses=environmental degradation, annihilation of the railroad and railroaders, diseases).

O presente estudo analisou aspectos do ciclo de vida e níveis de metais em Atherinella brasiliensis da praia de Itamambuca, Ubatuba (SP). As coletas foram mensais, nos períodos diurno e noturno, de setembro de 2003 a fevereiro de 2005, em quatro estações na praia e uma no rio Itamambuca, utilizando-se picaré. Os indivíduos migram diariamente para dentro do rio no período noturno. O melhor ajuste ao modelo de von Bertalanffy (CT= 164,85*(1-e-2,16(t+0,0038))) e à longevidade (A0,95= 1,378 ano) foi obtido pelo método de Ford-Walford. O índice de performance de crescimento e a mortalidade variaram de 2,77 a 2,91 e 1,64 a 1,82 ano-1, respectivamente. O valor de L50 estimado para sexos agrupados foi 86,6 mm, e os de RGS, DK e a freqüência de desovantes sugerem desova durante todo o ano, com maior intensidade do final da primavera até início do outono. A desova é parcelada, com alta freqüência e em pequenos lotes. Altas concentrações de Cr, Fe e Zn foram detectadas na musculatura, sendo maiores em indivíduos jovens e na alta temporada turística. Pode-se concluir que o peixe-rei passa todo seu ciclo de vida na praia de Itamambuca, apresenta altas taxas de crescimento e mortalidade natural, e desova ao longo de todo o ano. / The present study analyzed the life history and metal levels of Atherinella brasiliensis from Itamambuca beach, Ubatuba (SP). Surveys were conducted monthly, in diurnal and nocturnal periods, between September 2003 and February 2005, in four stations at the beach and one at the Itamambuca river, using beach seine. Individuals showed daily migration into the river at nocturnal period. The better adjustment to von Bertalanffy?s model (Lt = 164.85*(1-e-2.16(t+0.0038))) and to longevity (A0.95= 1.378 year) was obtained through Ford-Walford method. The value of estimated L50 for grouped gender was 86.6 mm, and the GSR, the DK and the spawning frequency suggest spawning during all year around, with higher intensity in late spring until middle autumn. The high frequency of spawning and the low batch fecundity indicate that the species is a batch spawner. High concentrations of Cr, Fe and Zn were detected in musculature, being higher among young individuals, and during tourist high season. In conclusion, the Brazilian silverside spends its life cycle on the Itamambuca beach, shows high growth and natural mortality rates, and spawning throughout the year.

Made available in DSpace on 2016-04-28T20:15:32Z (GMT). No. of bitstreams: 1 2009 - Huarrisson Azevedo Santos.pdf: 780165 bytes, checksum: de6d416bd5e351432ab7a787d05594f2 (MD5) Previous issue date: 2009-02-20 / The objective of the present study was to describe the biological aspects of Argas (Persicargas) miniatus in controlled conditions to 27?1?C and 80?10% (RH) and outdoor condition. The eggs originated of A. (P.) miniatus females were incubated in conditions mentioned above. The emerged larvae were fed in chick, while the nymphal and adult stages were fed in chicken. The nymphal instars biological characteristics were studied to 15, 30 and 60 days fast periods. The biological aspects of nymphal and adult stages were studied in outdoor condition in the dry (May to October) and rainy (November to April) station. The feeding time, recovery percentage, mortality percentage, weight before and after feeding, molting periods, preoviposition and oviposition, daily eggs output, incubation period, hatching percentage, estimated reproduction and nutritional index were evaluated. The larvae medium weight was 0,94 ? 0,13mg with a medium weight gain of approximately 81,37 times. In acclimatized camera the molting medium period was 6,37?0,24 days, while in outdoor conditions it was 8,12?0,95 days. When evaluated the larvae fixation capacity submitted to different fast periods was observed that unfed larvae maintained in acclimatized camera and outdoor conditions were capable to attachment in birds with fast periods from 6 to 75 days and 8 to 60 days, respectively. When nymphs were submitted to 15 and 30 days fast periods, in both conditions, the development of second and third nymphal instars happened. When submitted to 60 fast period days were verified mortality of 28 and 37% in acclimatized camera and outdoor condition, respectively and survivors do not attachment on the hosts. The nymphs of second instar submitted to 60 fast days developed, in both conditions, in third nymphal instar and male adults. Still in the group submitted to 60 fast days, the nymphs of third instar developed in adults (42,42% and 40,54% males; 36,36% and 48,65% females in outdoor condition and acclimatized camera, respectively) and the others developed in third nymphs instars, and further, developed in female adults. The medium number of produced eggs varied of 46 to 138 eggs in the 18 female s oviposition maintained in controlled conditions; 41 to 108 eggs in the 9 female s oviposition at the rainy station; and 74 to 138 eggs for the females at the dry station, with significant difference in all experimental conditions. The medium duration of the cycle with adults occurrence in N2 was 49.05 days in acclimatized camera, 53.01 days in the dry station and 67.41 days in the rainy station. The results obtained in the present study demonstrate that the biological aspects of A. (P.) miniatus are influenced by climatic factors, occurring a biological cycle prolongation during the dry station, period that the temperature is lower. / O objetivo do presente estudo foi descrever os aspectos biol?gicos de Argas (Persicargas) miniatus em condi??es controladas a 27?1?C e 80?10% (UR) e ambiente de laborat?rio. Os ovos oriundos de f?meas de A. (P.) miniatus foram incubados nas condi??es descritas acima. As larvas emergidas foram alimentadas em aves jovens, enquanto que os est?gios ninfais e adultos foram alimentados em aves adultas. As caracter?sticas biol?gicas dos ?nstares ninfais foram estudadas em per?odos de jejum de 15, 30 e 60 dias. Os aspectos biol?gicos dos est?gios ninfais e adultos foram estudados em condi??o ambiente de laborat?rio nas esta??es secas (Maio a Outubro) e chuvosas (Novembro a Abril). Foram avaliados: tempo de alimenta??o, taxa de recupera??o, taxa de mortalidade, peso antes e ap?s a alimenta??o, per?odos de muda, pr?-postura e postura, n?mero de posturas e de ovos, per?odo de incuba??o, percentual de eclos?o, reprodu??o estimada e ?ndice nutricional. O peso m?dio das larvas foi de 0,94 ? 0,13mg com ganho m?dio de peso de aproximadamente 81,37 vezes. Em c?mara climatizada o per?odo m?dio de muda foi de 6,37?0,24 dias, enquanto que em condi??es de ambiente de laborat?rio a m?dia foi 8,12?0,95 dias. Ao avaliar a capacidade de fixa??o de larvas submetidas a diferentes per?odos de jejum observou-se que as larvas n?o alimentadas mantidas em c?mara climatizada e em condi??es ambientais de laborat?rio foram capazes de se fixar sobre as aves com per?odos de jejum de 6 a 75 dias e 8 a 60 dias, respectivamente. Quando as ninfas foram submetidas a um per?odo de jejum de 15 e 30 dias, nas duas condi??es estudadas, ocorreu o desenvolvimento de ninfas de segundo e terceiro instares. Quando submetidas a 60 dias de jejum verificou-se mortalidade de 28 e 37% em c?mara climatizada e em ambiente de laborat?rio, respectivamente e as sobreviventes n?o se fixaram sobre os hospedeiros. As ninfas de segundo instar submetidas ao jejum de 60 dias desenvolveram, em ambas condi??es estudadas, ninfas de terceiro instar e adultos machos. Ainda no grupo submetido a 60 dias de jejum, as ninfas de terceiro instar desenvolveram adultos (42,42% e 40,54% de machos; 36,36% e 48,65% f?meas nas condi??es de ambiente de laborat?rio e B.O.D., respectivamente) e as demais se desenvolveram em ninfas de quarto instar, que posteriormente, se desenvolveram em adultos f?meas. O n?mero m?dio de ovos produzidos variou entre 46 e 138 ovos nas 18 posturas das f?meas mantidas em ambiente controlado; 41 e 108 ovos nas 9 posturas das f?meas das esta??es chuvosas; e 74 e 138 ovos para as f?meas da esta??o seca, com diferen?a significativa em todas as condi??es experimentais. A dura??o m?dia do ciclo com ocorr?ncia de adultos em N2 foi de 49,05 dias em c?mara climatizada, 53,01 dias nas esta??es secas e 67,41 dias nas esta??es chuvosas. Os resultados obtidos no presente estudo demonstram que os aspectos biol?gicos de A. (P.) miniatus s?o influenciados por fatores clim?ticos, de modo que ocorre um prolongamento do ciclo biol?gico durante a esta??o seca, per?odo que a temperatura ? mais baixa.

Made available in DSpace on 2016-04-28T20:38:41Z (GMT). No. of bitstreams: 1 Edneia Salviano da Silva Santos.pdf: 2696982 bytes, checksum: 8558e1191d06efaf6fcdc3eda8c1db5d (MD5) Previous issue date: 2013-05-24 / The objective of this research was to analyze how psychology courses are working with the theme of ageing and old age, and to confirm whether, with the growing senior citizen population, universities are preparing qualified professionals to work in this field, increasing the area of study beyond the physical aspects of this population to include the psychosocial approach. To do this, a thorough analysis of the curriculums of public and private universities of Brazil s south and southeast regions, which comprise the country s largest number of over 60 s, was undertaken. Based on bibliographic research on the theme of the ageing process and old age, it was found that the Human Development Theory should be applied beyond adulthood to include senior citizens over 80, and should also consider the familial, social and psychological aspects of this age group. Furthermore, documentary studies were undertaken in order to use, compare and analyze data in the public domain, specifically obtained on the internet, about syllabuses and curriculums posted on academic institutions websites. Eleven (11) universities that offer psychology courses in their curriculum with mandatory or elective classes either on or about ageing or old age were analyzed. The social role of universities includes the need for a greater awareness of their own importance in the formation of professionals that can meet society s current needs, as stated in the national curriculum guidelines. However, it was found that current thinking from the biopsychosocial perspective on human ageing is barely addressed by the undergraduate psychology programs studied. Psychology professionals, as members of the health care profession, should be well versed, upon graduating, in the theories of the ageing process and old age, in addition to those of adult development, and be sure of their own views on ageing, illness, and death. In response to these shortcomings, and the changing demographics of the country, the creation of national curriculum guidelines for education on ageing and human longevity for psychology courses is suggested / Esta pesquisa teve como objetivo analisar como os cursos de psicologia estão trabalhando a temática do envelhecimento e velhice e verificar se, diante do aumento da população de idosos, a universidade está preparando profissionais qualificados para a atuação com esse seguimento, ampliando o estudo para além do campo biológico, incluindo o campo psicossocial. Para isso, optou-se em analisar as grades curriculares de universidades públicas e privadas, localizadas nas Regiões Sudeste e Sul, regiões onde, atualmente, encontram-se o maior número de pessoas acima de 60 anos. A partir do levantamento bibliográfico feito sobre a temática: processo de envelhecimento e velhice, constatou-se que a teoria do desenvolvimento humano deve ser estendida além da etapa da adultez, incluindo a quarta idade (acima de 80 anos) e que se deve considerar aspectos familiares, sociais e psicológicos no trato com essa população. Além disso, optou-se pelo método do estudo documental, para utilizar, comparar e analisar as informações de domínio público, especificamente obtidas via internet, das grades e ementas disponibilizadas nos sites das instituições acadêmicas. Foram analisadas 11 universidades, que oferecem, na grade curricular, dos cursos de psicologia, alguma disciplina obrigatória ou optativa, versando sobre questões relacionadas ao tema envelhecimento e/ou velhice. A função social da universidade inclui a necessidade de uma maior conscientização de sua importância na formação de profissionais que respondam às demandas atuais da sociedade, como consta nas diretrizes curriculares nacionais. No entanto, constatou-se que aspectos contemporâneos da visão biopsicossocial do envelhecimento humano ainda se constituem em um tema com abordagem mínima nas grades dos cursos de graduação em psicologia analisados. O profissional de psicologia, como integrante da área de Saúde, deveria ser capacitado, na graduação, nas teorias que abordam o envelhecimento e velhice além do desenvolvimento adulto e, pessoalmente, rever suas concepções sobre o envelhecer, adoecer e morrer. Ante tal lacuna e as mudanças demográficas do país, sugere-se a criação de Diretrizes Curriculares Nacionais para Educação do Envelhecimento e Longevidade Humana nas grades curriculares dos cursos de Psicologia

Teachers of students with emotional and behavioral disorders (EBD) have among the highest attrition rates of any teaching discipline in the United States. High attrition rates affect EBD teachers, school districts, and students with EBD. Through the theoretical lenses of Maslow's hierarchy of needs theory and Eisenberger's organizational support theory (OST), this study sought to determine if there was a difference in college preparation, job support, and job benefit/amenity factors identified by EBD teachers who intended to leave the discipline (n = 6) and those who intended to stay (n = 9). This quantitative, survey-based study yielded data from 15 EBD teachers. Results of independent-samples t-tests indicated there were no statistically significance differences in responses between the 2 groups. However, there were notable differences when the highest and lowest means scores of individual survey items were examined. The importance both groups placed on job supports when compared to college preparation and job benefit/amenities was evident. Additionally, the results indicated that EBD teachers planning on leaving the profession placed more importance on direct contact with school administrators when compared with those intending to stay. Results of this study should be taken with caution as they are drawn from a relatively small sample of EBD teachers. The results of the study may add to the field of research on EBD teacher attrition rates and possibly assist universities, educational leaders, and education policy makers in developing means to address this issue. Importantly, the results of the study could promote the professional success of EBD teachers as well as the academic, behavioral, and social growth of the students they teach.

Women entrepreneurs are emerging in the national economy as important players, yet gender bias and stereotypes still exist in organizations that prevent firms from taking advantage of women'€™s potential as leaders in entrepreneurial ventures. At the same time, traditional leadership models are lacking in diversity and unanswered questions remain regarding the role of gender in entrepreneurial leadership and enterprise sustainability. The purpose of this qualitative study, which used an exploratory, multiple-case research design, was to gain insight into the leadership practices of women entrepreneurial leaders and the implications of these practices for enterprise longevity 5 years after their business'€™s start-up phase. This study is framed by, first, the concept of the entrepreneurial leader and, second the intersectionality of gender and entrepreneurial leadership. Semistructured interviews with 9 participants, observational field notes, and archival data provided data regarding the leadership experiences of women entrepreneurs and enterprise longevity of women-led firms. Identifiable themes emerged through thematic analysis of the textual data and cross-case synthesis analysis. A total of 7 conceptual categories that enclose a total of 12 themes were identified. The conceptual categories are (a) gender, (b) entrepreneurial leadership, (c) market, (d) money, (e) management skills, (f) macro environment, and (g) meso environment. Findings from this study may serve as a catalyst for social change by challenging the status quo in existing formal work structures and promoting diversity in the workplace, opening new avenues for business growth and building bridges of communication between the business world and society.

Mutual fund portfolio managers do not always meet risk-adjusted performance expectations, resulting in loss of capital reserves. Out of 3,612 U.S. based open-ended mutual funds, the risk-adjusted performance of 2,890 (80%) failed to meet or beat the S&P 500 (index fund) performance between the year 2006 to 2016. Grounded in Markowitz's modern portfolio theory, the purpose of this correlational study was to examine the relationship between mutual fund class type, portfolio turnover, fund longevity, management turnover, and annual fund risk-adjusted performance. Archival data were collected from 88 U.S. based equity mutual funds companies. The results of the multiple regression analysis indicated the model as a whole was able to significantly predict annual fund risk-adjusted performance for the 5-year period ending 2016, F (4, 83) = 3.581, p =.043, R2 = .147. In the final model, mutual fund class type and portfolio turnover were statistically significant with mutual fund class type (Ã?= .249, t = 2.302, p = .024) accounting for a higher contribution to the model than portfolio turnover (Ã? = .238, t = 2.312, p = .023). Mutual fund longevity and management turnover did not explain any significant variance in annual fund risk-adjusted performance. Society can benefit from the results of this doctoral study because investors and mutual fund managers could better predict the return based on the information from the study, which may lead to higher families' confidence in the positive contribution of the mutual fund in their portfolio.

Wireless Sensor Networks (WSNs) continue to evolve as new applications emerge. In the recent past, WSNs were mostly single sink networks with a few number of homogeneous and static sensor nodes. Now, several applications require networks with multiple and moving sinks and targets as well as thousands of heterogeneous devices. However, the same constraints remain: sensor nodes continue to be very limited in resources, posing new challenges in the design of scalable and energy-efficient algorithms and communication protocols to support these new applications. This dissertation first addresses the problem of sink localization in large scale WSNs. A scalable and energy-efficient sink localization mechanism, called the Anchor Location Service (ALS), is introduced to support the use of location-based routing protocols. ALS avoids frequent and costly flooding procedures derived from the mobility of the sinks and targets, and utilizes face routing to guarantee the success of localization. The problem of topology control in heterogeneous environments is addressed next. A new topology control mechanism, the Residual Energy-Aware Dynamic (READ) algorithm, is devised to extend the lifetime of the network while maintaining connectivity. READ extends the lifetime of the network by assigning a more prominent role to more powerful devices. ALS and READ are evaluated and compared with other well-known protocols using analytical means and simulations. Results show that ALS provides a scalable sink location service and reduces the communication overhead in scenarios with multiple and moving sinks and targets. Results also show that READ increases both the network lifetime and the packet delivery rate.

1. Introduction This dissertation consists of six chapters that span a very diverse set of topics. Yet, it has two unifying themes, economics and biology, that tie it together. The first four chapters present the principal findings from a project that was initiated jointly with David Cesarini and Magnus Johannesson, and that applies the twin method from behavioral genetics to economics. The last two chapters instead use a simple regression framework and evidence from biological anthropology to investigate recent claims regarding the effects of child bearing and past slave trades. 2. Genes and economics There is a small, but rapidly growing, literature studying the genetic and environmental origins of economic behavior and outcomes (Bowles et al., 2005; Beauchamp et al., 2011). Until recently, this literature focused exclusively on outcomes, and in particular income. In chapters 1-4 we instead focus on economic behavior and decision-making. Previous behavioral genetic work outside the domains of economics has changed the way that we think about a number of behavioral traits. In this literature it is typically found that i) variation is heritable ii) genetic factors are more important than family environment iii) a large fraction of variation cannot be explained by neither genes nor family environment (Turkheimer, 2000; Plomin et al., 2009). However, compared to many other disciplines, and psychology in particular, economics is lagging behind. In fact, as recently as 2009 the leading text book in behavioral genetics described economics as "still essentially untouched by genetic research" (Plomin et al., 2009, p. 353). Hopefully, the chapters in this dissertation can help to improve on this somewhat unsatisfactory state of the art. Chapters 1 and 2 study economic decision-making in the laboratory using the twin method. More specifically, we study the ultimatum and dictator games alongside risky gambles, using same-sex twin pairs as our subject pool. Given a few additional assumptions, the fact that identical twins have, in expectation, a twice as high coefficient of genetic relatedness as fraternal twins implies that we can study the genetic and environmental contributions to variation in behavior by studying twin correlations in observed choices. Chapters 3 and 4 apply the same method to actual portfolio choices associated with a far-reaching pension reform, as well as to a set of standard behavioral anomalies. Taken together, these four chapters provide strong evidence in favor of the hypothesis that genes influence economic decision-making. Thus, economic behavior does not appear to be much different from other types of behavior. 3. Economics and history The last two chapters of the dissertation turn to the past, rather than genes, in an effort to evaluate recent findings regarding two important welfare outcomes. In chapter 5 we investigate Nunn’s (2008) claim that past slave trades had a negative impact on current economic performance in Africa. By extending the sample period back in time we demonstrate that this relationship was not significant in 1960. In addition, by applying Nunn’s method to an episode of large scale slave raiding in Italy, we demonstrate that there exists a similar negative relationship across Italian regions, although it becomes insignificant when geographical controls are included. Intriguingly, going back to 1960, the coefficient on slave raids for Italy also has a similar time trend to that for Africa. Taking these facts, and our reading of the historical and anthropological literature, which is much different from that of Nunn, into account we do not find much support for the hypothesis that the African slave trades had a negative impact on current economic performance. Finally, chapter 6 investigates the large and negative relationship between giving birth to a son, rather than a daughter, and maternal longevity that was documented in a Sami hunter-gatherer population from Finland (Helle et al., 2002). Using a substantially larger sample of pre-industrial Swedish Sami we find no evidence in favor of such a relationship. 4. Brasklapp Five of the chapters in this dissertation (Ch. 1-4 &amp; 6) are slightly altered versions of previously published papers (Wallace et al., 2007; Cesarini et al., 2009 a, b; 2010; 2011). Unfortunately, the fact that earlier versions of the chapters were prepared as separate articles for five different journals means that they can at times appear both repetitive, and in terms of notation and formatting, somewhat inconsistent. I apologize to the reader for these inconveniences. / <p>Diss. Stockholm :  Stockholm School of Economics, 2011. Introduction together with 6 papers</p>

A large proportion of the world’s nitrogen needs is derived from symbiotic nitrogen fixation (SNF), which contributes substantially to agricultural sustainability. The partnership between legumes and rhizobia result in the formation of specialised structures called root nodules. Within these nodules SNF is supported by the sucrose transported from the leaves to the nodules for respiration. The end products of SNF in soybean (Glycine max (L.) Merr.) root nodules, namely ureides, are transported to the upper parts of the plant to supply nitrogen. Symbiotic nitrogen fixation provides a vital advantage for the production of soybean compared with most grain crops in that soybean fixes the nitrogen required for its growth and for the production of the high-protein content in seed and oil. The process of SNF is dramatically affected by drought, salt, cold and heavy metal stresses. Since SNF is such an important yield-determining factor, a lack in understanding these complexes inevitably delays progress towards the genetic improvement of soybean genotypes and also complicates decisions with regard to the suitability of certain genotypes for the various soybean producing areas in South Africa. The largest soybean producing areas in South Africa are situated at high altitudes, with minimum daily temperatures which can be critically low and impeding the production of soybean. Soybean is chilling sensitive, with growth, development and yield being affected negatively at temperatures below 15°C. Dark chilling (low night temperature) stress has proved to be one of the most important restraints to soybean production in South Africa. Among the symptoms documented in dark chilling sensitive soybean genotypes are reduced growth rates, loss of photosynthetic capacity and pigment content, as well as premature leaf senescence and severely inhibited SNF. Existing knowledge about stress-induced nodule senescence is based on fragmented information in the literature obtained in numerous, and often diverse, legume species. The precise nature and sequence of events participating in nodule senescence has not yet been fully explained. The main objectives of this investigation were to characterise the natural senescence process in soybean nodules under optimal growth conditions and to characterise the alteration of the key processes of SNF in a chilling sensitive soybean genotype during dark chilling. Moreover, to establish whether recovery in nodule functionality following a long term dark chilling period occured, or whether nodule senescence was triggered, and if sensitive biochemical markers of premature nodule senescence could be identified. A known chilling sensitive soybean genotype, PAN809, was grown under controlled growth conditions in a glasshouse. To determine the baseline and change over time for key parameters involved in SNF, a study was conducted under optimal growing conditions over a period of 6 weeks commencing 4 weeks after sowing. The cluster of crown nodules were monitored weekly and analysis included nitrogenase activity, ureide content, respiration rate, leghemoglobin content, sucrose synthase (SS) activity and sucrose content. Further investigations focused on induced dark chilling effects on nodule function to determine the alterations in key parameters of SNF. Plants were subjected to dark chilling (6˚C) for 12 consecutive nights and kept at normal day temperatures (26˚C). The induced dark chilling was either only shoot (SC) exposure or whole plant chilling (WPC). These treatments were selected since, in some areas in South Africa cold nights result not only in shoot chilling (SC) but also in low soil temperatures causing direct chilling of both roots and shoots. To determine if premature nodule senescence was triggered, the recovery following 12 consecutive nights of chilling treatment was monitored for another 4 weeks. It was established that the phase of optimum nitrogenase activity under optimal growing conditions occurred during 4 to 6 weeks after sowing where after a gradual decline commenced. This decline was associated with a decline in nitrogenase protein content and an increase in ureide content. The stability of SS activity and nodule respiration showed that carbon-dependent metabolic processes were stable for a longer period than previously mentioned parameters. The negative correlation that was observed between nitrogenase activity and nodule ureide content pointed towards the possible presence of a feedback inhibition trigger on nitrogenase activity. A direct effect of dark chilling on nitrogenase activity and nodule respiration rate led to a decline in nodule ureide content that occurred without any limitations on the carbon flux of the nodules (i.e. stable sucrose synthase activity and nodule sucrose content). The effect on SC plants was much less evident but did indicate that currently unknown shoot-derived factors could be involved in the minor inhibition of SNF. It was concluded that the repressed rates of respiration might have led to increased O2 concentrations in the nodule, thereby inhibiting the nitrogenase protein and so the production of ureides. It was found that long term chilling severely disrupted nitrogenase activity and ureide synthesis in nodules. Full recovery in all treatments occurred after 2 weeks of suspension of dark chilling, however, this only occurred when control nodules already commenced senescence. This points toward reversible activation of the nitrogenase protein with no evidence in support of premature nodule senescence. An increase in intercellular air space area was induced by long term dark chilling in nodules, specifically by the direct chilling of nodules (WPC treatment). The delayed diminishment of intercellular air space area back to control levels following dark chilling may be an important factor involved in the recovery of nitrogenase activity because enlarged air spaces would have favoured gaseous diffusion, and hence deactivation of nitrogenase, in an elevated O2 environment (due to supressed nodule respiration rates). These findings revealed that dark chilling did not close the diffusion barrier, as in the case of drought and other stress factors, but instead opened it due to an increase in air space areas in all regions of the nodule. In conclusion, this study established that dark chilling did not initiate premature nodule senescence and that SNF demonstrated resilience, with full recovery possible following even an extended dark chilling period involving low soil temperatures. / Thesis(PhD (Botany))--North-West University, Potchefstroom Campus, 2013