Growth rates and biometric measurements of coccolithophores (Coccolithus pelagicus, Coccolithus braarudii, Emiliania huxleyi) during experiments

Coccolithophores, a diverse group of phytoplankton, make important contributions to pelagic calcite production and export, yet the comparative biogeochemical role of species other than the ubiquitous Emiliania huxleyi is poorly understood. Here we examined the relative importance of E. huxleyi and two Coccolithus species (Coccolithus pelagicus and Coccolithus braarudii), in terms of daily calcite production, by culturing E. huxleyi and Coccolithus in parallel, and comparing growth rates and biometrically determined cellular carbon calcite quotas. Biometric measurements of Coccolithus species, and E. huxleyi cell diameters, were performed using polarised light microscopy. Scanning electron microscopy was used for all other biometric measurements of E. huxleyi.

Ocean acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light, link to supplementary data

There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton. The aim of the present study was to investigate interactive effects of OA and dynamic light, mimicking natural mixing regimes. The Antarctic diatom Chaetoceros debilis was grown under two pCO2 (390 and 1000 latm) and light conditions (constant and dynamic), the latter yielding the same integrated irradiance over the day. To characterize interactive effects between treatments, growth, elemental composition, primary production and photophysiology were investigated. Dynamic light reduced growth and strongly altered the effects of OA on primary production, being unaffected by elevated pCO2 under constant light, yet significantly reduced under dynamic light. Interactive effects between OA and light were also observed for Chl production and particulate organic carbon (POC) quotas. Response patterns can be explained by changes in the cellular energetic balance. While the energy transfer efficiency from photochemistry to biomass production (Phi_e,C) was not affected by OA under constant light, it was drastically reduced under dynamic light. Contrasting responses under different light conditions need to be considered when making predictions regarding a more stratified and acidified future ocean.

Seawater carbonate chemistry and processes during experiments with cyanobacterium Trichodesmium (IMS101), 2009

We investigated carbon acquisition by the N2-fixing cyanobacterium Trichodesmium IMS101 in response to CO2 levels of 15.1, 37.5, and 101.3 Pa (equivalent to 150, 370, and 1000 ppm). In these acclimations, growth rates as well as cellular C and N contents were measured. In vivo activities of carbonic anhydrase (CA), photosynthetic O2 evolution, and CO2 and HCO3- fluxes were measured using membrane inlet mass spectrometry and the 14C disequilibrium technique. While no differences in growth rates were observed, elevated CO2 levels caused higher C and N quotas and stimulated photosynthesis and N2 fixation. Minimal extracellular CA (eCA) activity was observed, indicating a minor role in carbon acquisition. Rates of CO2 uptake were small relative to total inorganic carbon (Ci) fixation, whereas HCO{3 contributed more than 90% and varied only slightly over the light period and between CO2 treatments. The low eCA activity and preference for HCO3- were verified by the 14C disequilibrium technique. Regarding apparent affinities, half-saturation concentrations (K1/2) for photosynthetic O2 evolution and HCO3- uptake changed markedly over the day and with CO2 concentration. Leakage (CO2 efflux : Ci uptake) showed pronounced diurnal changes. Our findings do not support a direct CO2 effect on the carboxylation efficiency of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) but point to a shift in resource allocation among photosynthesis, carbon acquisition, and N2 fixation under elevated CO2 levels. The observed increase in photosynthesis and N2fixation could have potential biogeochemical implications, as it may stimulate productivity in N-limited oligotrophic regions and thus provide a negative feedback in rising atmospheric CO2 levels.

Polar membrane lipids and elemental composition of Thermococcus kodakarensis cells according to growth stage and phosphorus supply

We observed significant changes in the elemental and intact polar lipid (IPL) composition of the archaeon Thermococcus kodakarensis (KOD1) in response to growth stage and phosphorus supply. Reducing the amount of organic supplements and phosphate in growth media resulted in significant decreases in cell size and cellular quotas of carbon (C), nitrogen (N), and phosphorus (P), which coincided with significant increases in cellular IPL quota and IPLs comprising multiple P atoms and hexose moieties. Relatively more cellular P was stored as IPLs in P-limited cells (2-8%) compared to control cells (<0.8%). We also identified a specific IPL biomarker containing a phosphatidyl-N-acetylhexoseamine headgroup that was relatively enriched during rapid cell division. These observations serve as empirical evidence of IPL adaptations in Archaea that will help to interpret the distribution of these biomarkers in natural systems. The reported cell quotas of C, N, and P represent the first such data for a specific archaeon and suggest that thermophiles are C-rich compared to the cell carbon-to-volume relationship reported for planktonic bacteria.

Effects of increasing seawater carbon dioxide concentrations on chain formation of the diatom Asterionellopsis glacialis

Diatoms can occur as single cells or as chain-forming aggregates. These two strategies affect buoyancy, predator evasion, light absorption and nutrient uptake. Adjacent cells in chains establish connections through various processes that determine strength and flexibility of the bonds, and at distinct cellular locations defining colony structure. Chain length has been found to vary with temperature and nutrient availability as well as being positively correlated with growth rate. However, the potential effect of enhanced carbon dioxide (CO2) concentrations and consequent changes in seawater carbonate chemistry on chain formation is virtually unknown. Here we report on experiments with semi-continuous cultures of the freshly isolated diatom Asterionellopsis glacialis grown under increasing CO2 levels ranging from 320 to 3400 µatm. We show that the number of cells comprising a chain, and therefore chain length, increases with rising CO2 concentrations. We also demonstrate that while cell division rate changes with CO2 concentrations, carbon, nitrogen and phosphorus cellular quotas vary proportionally, evident by unchanged organic matter ratios. Finally, beyond the optimum CO2 concentration for growth, carbon allocation changes from cellular storage to increased exudation of dissolved organic carbon. The observed structural adjustment in colony size could enable growth at high CO2 levels, since longer, spiral-shaped chains are likely to create microclimates with higher pH during the light period. Moreover increased chain length of Asterionellopsis glacialis may influence buoyancy and, consequently, affect competitive fitness as well as sinking rates. This would potentially impact the delicate balance between the microbial loop and export of organic matter, with consequences for atmospheric carbon dioxide.

CO2 and vitamin B12 interactions determine bioactive trace metal requirements of a subarctic Pacific diatom

Phytoplankton growth can be limited by numerous inorganic nutrients and organic growth factors. Using the subarctic diatom Attheya sp. in culture studies, we examined how the availability of vitamin B(12) and carbon dioxide partial pressure (pCO(2)) influences growth rate, primary productivity, cellular iron (Fe), cobalt (Co), zinc (Zn) and cadmium (Cd) quotas, and the net use efficiencies (NUEs) of these bioactive trace metals (mol C fixed per mol cellular trace metal per day). Under B(12)-replete conditions, cells grown at high pCO(2) had lower Fe, Zn and Cd quotas, and used those trace metals more efficiently in comparison with cells grown at low pCO(2). At high pCO(2), B(12)-limited cells had ~50% lower specific growth and carbon fixation rates, and used Fe ~15-fold less efficiently, and Zn and Cd ~3-fold less efficiently, in comparison with B(12)-replete cells. The observed higher Fe, Zn and Cd NUE under high pCO(2)/B(12)-replete conditions are consistent with predicted downregulation of carbon-concentrating mechanisms. Co quotas of B(12)-replete cells were 5- to 14-fold higher in comparison with B(12)-limited cells, suggesting that >80% of cellular Co of B(12)-limited cells was likely from B(12). Our results demonstrate that CO(2) and vitamin B(12) interactively influence growth, carbon fixation, trace metal requirements and trace metal NUE of this diatom. This suggests the need to consider complex feedback interactions between multiple environmental factors for this biogeochemically critical group of phytoplankton in the last glacial maximum as well as the current and future changing ocean.

Construcción modular ligera energéticamente eficiente

Esta tesis trata sobre la construcción modular ligera, dentro del contexto de la eficiencia energética y de cara a los conceptos de nZEB (near Zero Energy Building) y NZEB (Net Zero Energy Building) que se manejan en el ámbito europeo y específicamente dentro del marco regulador de la Directiva 2010/31 UE. En el contexto de la Unión Europea, el sector de la edificación representa el 40% del total del consumo energético del continente. Asumiendo la necesidad de reducir este consumo se han planteado, desde los organismos de dirección europeos, unos objetivos (objetivos 20-20-20) para hacer más eficiente el parque edificatorio. Estos objetivos, que son vinculantes en términos de legislación, comprometen a todos los estados miembros a conseguir la meta de reducción de consumo y emisiones de GEI (Gases de Efecto Invernadero) antes del año 2020. Estos conceptos de construcción modular ligera (CML) y eficiencia energética no suelen estar asociados por el hecho de que este tipo de construcción no suele estar destinada a un uso intensivo y no cuenta con unos cerramientos con niveles de aislamiento de acuerdo a las normativas locales o códigos de edificación de cada país. El objetivo de nZEB o NZEB, e incluso Energy Plus, según sea el caso, necesariamente (y así queda establecido en las normativas), dependerá no sólo de la mejora de los niveles de aislamiento de los edificios, sino también de la implementación de sistemas de generación renovables, independientemente del tipo de sistema constructivo con el que se trabaje e incluso de la tipología edificatoria. Si bien es cierto que los niveles de industrialización de la sociedad tecnológica actual han alcanzado varias de las fases del proceso constructivo - sobre todo en cuanto a elementos compositivos de los edificios- también lo es el hecho de que las cotas de desarrollo conseguidas en el ámbito de la construcción no llegan al nivel de evolución que se puede apreciar en otros campos de las ingenierías como la aeronáutica o la industria del automóvil. Aunque desde finales del siglo pasado existen modelos y proyectos testimoniales de construcción industrializada ligera (CIL) e incluso ya a principios del siglo XX, ejemplos de construcción modular ligera (CML), como la Casa Voisin, la industrialización de la construcción de edificios no ha sido una constante progresiva con un nivel de comercialización equiparable al de la construcción masiva y pesada. Los términos construcción industrializada, construcción prefabricada, construcción modular y construcción ligera, no siempre hacen referencia a lo mismo y no siempre son sinónimos entre sí. Un edificio puede ser prefabricado y no ser modular ni ligero y tal es el caso, por poner un ejemplo, de la construcción con paneles de hormigón prefabricado. Lo que sí es una constante es que en el caso de la construcción modular ligera, la prefabricación y la industrialización, casi siempre vienen implícitas en muchos ejemplos históricos y actuales. Con relación al concepto de eficiencia energética (nZEB o incluso NZEB), el mismo no suele estar ligado a la construcción modular ligera y/o ligera industrializada; más bien se le ve unido a la idea de cerramientos masivos con gran inercia térmica propios de estándares de diseño como el Passivhaus; y aunque comúnmente a la construcción ligera se le asocian otros conceptos que le restan valor (corta vida útil; función y formas limitadas, fuera de todo orden estético; limitación en los niveles de confort, etc.), los avances que se van alcanzando en materia de tecnologías para el aprovechamiento de la energía y sistemas de generación renovables, pueden conseguir revertir estas ideas y unificar el criterio de eficiencia + construcción modular ligera. Prototipos y proyectos académicos– como el concurso Solar Decathlon que se celebra desde el año 2002 promovido por el DOE (Departamento de Energía de los Estados Unidos), y que cuenta con ediciones europeas como las de los años 2010 y 2012, replantean la idea de la construcción industrializada, modular y ligera dentro del contexto de la eficiencia energética, con prototipos de viviendas de ± 60m2, propuestos por las universidades concursantes, y cuyo objetivo es alcanzar y/o desarrollar el concepto de NZEB (Net Zero Energy Building) o edificio de energía cero. Esta opción constructiva no sólo representa durabilidad, seguridad y estética, sino también, rapidez en la fabricación y montaje, además de altas prestaciones energéticas como se ha podido demostrar en las sucesivas ediciones del Solar Decathlon. Este tipo de iniciativas de desarrollo de tecnologías constructivas, no sólo apuntan a la eficiencia energética sino al concepto global de energía neta, Energía plus o cero emisiones de CO2. El nivel de emisiones por la fabricación y puesta en obra de los materiales de construcción depende, en muchos casos, no solo de la propia naturaleza del material, sino también de la cantidad de recursos utilizados para producir una unidad de medida determinada (kg, m3, m2, ml, etc). En este sentido podría utilizarse, en muchos casos, el argumento válido de que a menos peso, y a menos tamaño, menos emisiones globales de gases de efecto invernadero y menos contaminación. Para el trabajo de investigación de esta tesis se han tomado como referencias válidas para estudio, prototipos tanto de CML (Modular 3D) como de CIL (panelizado y elementos 2D), dado que para los fines de análisis de las prestaciones energéticas de los materiales de cerramiento, ambos sistemas son equiparables. Para poder llegar a la conclusión fundamental de este trabajo de tesis doctoral - que consiste en demostrar la viabilidad tecnológica/ industrial que supone la combinación de la eficiencia energética y la construcción modular ligera - se parte del estudio del estado de la técnica ( desde la selección de los materiales y los posibles procesos de industrialización en fábrica, hasta su puesta en obra, funcionamiento y uso, bajo los conceptos de consumo cero, cero emisiones de carbono y plus energético). Además -y con un estado de la técnica que identifica la situación actual- se llevan a cabo pruebas y ensayos con un prototipo a escala natural y células de ensayo, para comprobar el comportamiento de los elementos compositivos de los mismos, frente a unas condicionantes climáticas determinadas. Este tipo de resultados se contrastan con los obtenidos mediante simulaciones informáticas basadas en los mismos parámetros y realizadas en su mayoría mediante métodos simplificados de cálculos, validados por los organismos competentes en materia de eficiencia energética en la edificación en España y de acuerdo a la normativa vigente. ABSTRACT This thesis discusses lightweight modular construction within the context of energy efficiency in nZEB (near Zero Energy Building) and NZEB (Net Zero Energy Building) both used in Europe and, specifically, within the limits of the regulatory framework of the EU Directive 2010/31. In the European Union the building sector represents 40% of the total energy consumption of the continent. Due to the need to reduce this consumption, European decision-making institutions have proposed aims (20-20-20 aims) to render building equipment more efficient. These aims are bound by law and oblige all member States to endeavour to reduce consumption and GEI emissions before the year 2020. Lightweight modular construction concepts and energy efficiency are not generally associated because this type of building is not normally meant for intensive use and does not have closures with insulation levels which fit the local regulations or building codes of each country. The objective of nZEB or NZEB and even Energy Plus, depending on each case, will necessarily be associated (as established in the guidelines) not only with the improvement of insulation levels in buildings, but also with the implementation of renewable systems of generation, independent of the type of building system used and of the building typology. Although it is true that the levels of industrialisation in the technological society today have reached several of the building process phases - particularly in the composite elements of buildings - it is also true that the quotas of development achieved in the area of construction have not reached the evolutionary levelfound in other fields of engineering, such as aeronautics or the automobile industry. Although there have been models and testimonial projects of lightweight industrialised building since the end of last century, even going back as far as the beginning of the XX century with examples of lightweight modular construction such as the Voisin House, industrialisation in the building industry has not been constant nor is its comercialisation comparable to massive and heavy construction. The terms industrialised building, prefabricated building, modular building and lightweight building, do not always refer to the same thing and they are not always synonymous. A building can be prefabricated yet not be modular or lightweight. To give an example, this is the case of building with prefabricated concrete panels. What is constant is that, in the case of lightweight modular construction, prefabrication and industrialisation are almost always implicit in many historical and contemporary examples. Energy efficiency (nZEB or even NZEB) is not normally linked to lightweight modular construction and/or industrialised lightweight; rather, it is united to the idea of massive closureswith high thermal inertia typical of design standards such as the Passive House; and although other concepts that subtract value from it are generally associated with lightweight building (short useful life, limited forms and function, inappropriate toany aesthetic pattern; limitation in comfort levels, etc.), the advances being achieved in technology for benefitting from energy and renewable systems of generation may well reverse these ideas and unify the criteria of efficiency + lightweight modular construction. Academic prototypes and projects - such as the Solar Decathlon competition organised by the US Department of Energy and celebrated since 2002, with its corresponding European events such as those held in 2010 and 2012, place a different slant on the idea of industrialised, modular and lightweight building within the context of energy efficiency, with prototypes of homes measuring approximately 60m2, proposed by university competitors, whose aim is to reach and/or develop the NZEB concept, or the zero energy building. This building option does not only signify durability, security and aesthetics, but also fast manufacture and assembly. It also has high energy benefits, as has been demonstrated in successive events of the Solar Decathlon. This type of initiative for the development of building technologies, does not only aim at energy efficiency, but also at the global concept of net energy, Energy Plus and zero CO2 emissions. The level of emissions in the manufacture and introduction of building materials in many cases depends not only on the inherent nature of the material, but also on the quantity of resources used to produce a specific unit of measurement (kg, m3, m2, ml, etc.). Thus in many cases itcould be validly arguedthat with less weight and smaller size, there will be fewer global emissions of greenhouse effect gases and less contamination. For the research carried out in this thesis prototypes such as the CML (3D Module) and CIL (panelled and elements) have been used as valid study references, becauseboth systems are comparablefor the purpose of analysing the energy benefits of closure materials. So as to reach a basic conclusion in this doctoral thesis - that sets out to demonstrate the technological/industrial viability of the combination of energy efficiency and lightweight modular construction - the departure point is the study of the state of the technique (from the selection of materials and the possible processes of industrialisation in manufacture, to their use on site, functioning and use, respecting the concepts of zero consumption, zero emissions of carbon and Energy Plus). Moreover, with the state of the technique identifying the current situation, tests and practices have been carried out with a natural scale prototype and test cells so as to verify the behaviour of the composite elements of these in certain climatic conditions. These types of result are contrasted with those obtained through computer simulation based on the same parameters and done, principally, using simplified methods of calculation, validated by institutions competent in energy efficiency in Spanish building and in line with the rules in force.

A QUALIFICAÇÃO E A INSERÇÃO NO MUNDO DO TRABALHO DA PESSOA PORTADORA DE DEFICIÊNCIA: UM ESTUDO SOBRE O IMPACTO DA EXTINÇÃO DA LEI 6.297/75

O presente estudo tem como objetivo, analisar sobre as dificuldades enfrentadas tanto pelas Empresas em cumprir a Legislação de Cotas, como também da Pessoa Portadora de Deficiência (PPDs) em ser inserida no mercado de trabalho, devido a falta de qualificação dos candidatos. Através da pesquisa literária ficou claro que nossa Legislação demonstra de forma evidente que o legislador pretendeu assegurar aos PPDs, as condições mínimas de participação influente na vida ativa da sociedade brasileira e num avanço sem precedentes, criaram-se as linhas básicas do processo de integração do deficiente à sociedade e ao mercado produtivo nacional. Verificou-se também que as empresas estão em busca de profissionais dentre o universo dos PPDs, já qualificados, o que normalmente não encontram. As Organizações do Direito Privado também já desenvolveram alguns projetos para a qualificação desses PPDs. A Lei 6.297/75 que garantia às empresas o desconto em dobro no IR dos gastos com treinamento, foi extinta em 12 de Dezembro de 1990. As empresas precisam de um incentivo financeiro para que possam tratar da qualificação desses profissionais, não mais como um peso, mas sim como um projeto social. Caso as empresas fossem beneficiadas por incentivos fiscais, assim como eram na vigência dessa Lei, teriam as empresas uma visão diferenciada por ocasião da contratação dos PPDs? A metodologia de pesquisa prevê um levantamento bibliográfico e uma pesquisa exploratória que será feita em empresas privadas, instituições que visam ajudar na inserção dos PPDs e nas Organizações do Direito Privado tais como Senai, Sesi, Força Sindical, Fiesp. Verificou-se, mediante a pesquisa, que há uma preocupação por parte de todos os envolvidos, em encontrar meios eficazes para garantir a inserção dos PPDs no mercado de trabalho, embora a falta de qualificação ainda seja o maior problema. A criação de Leis similares à Lei 6.297/75 foi apontada como uma grande ajuda às empresas, já que a elas foi imposta essa responsabilidade.(AU)

A QUALIFICAÇÃO E A INSERÇÃO NO MUNDO DO TRABALHO DA PESSOA PORTADORA DE DEFICIÊNCIA: UM ESTUDO SOBRE O IMPACTO DA EXTINÇÃO DA LEI 6.297/75

O presente estudo tem como objetivo, analisar sobre as dificuldades enfrentadas tanto pelas Empresas em cumprir a Legislação de Cotas, como também da Pessoa Portadora de Deficiência (PPDs) em ser inserida no mercado de trabalho, devido a falta de qualificação dos candidatos. Através da pesquisa literária ficou claro que nossa Legislação demonstra de forma evidente que o legislador pretendeu assegurar aos PPDs, as condições mínimas de participação influente na vida ativa da sociedade brasileira e num avanço sem precedentes, criaram-se as linhas básicas do processo de integração do deficiente à sociedade e ao mercado produtivo nacional. Verificou-se também que as empresas estão em busca de profissionais dentre o universo dos PPDs, já qualificados, o que normalmente não encontram. As Organizações do Direito Privado também já desenvolveram alguns projetos para a qualificação desses PPDs. A Lei 6.297/75 que garantia às empresas o desconto em dobro no IR dos gastos com treinamento, foi extinta em 12 de Dezembro de 1990. As empresas precisam de um incentivo financeiro para que possam tratar da qualificação desses profissionais, não mais como um peso, mas sim como um projeto social. Caso as empresas fossem beneficiadas por incentivos fiscais, assim como eram na vigência dessa Lei, teriam as empresas uma visão diferenciada por ocasião da contratação dos PPDs? A metodologia de pesquisa prevê um levantamento bibliográfico e uma pesquisa exploratória que será feita em empresas privadas, instituições que visam ajudar na inserção dos PPDs e nas Organizações do Direito Privado tais como Senai, Sesi, Força Sindical, Fiesp. Verificou-se, mediante a pesquisa, que há uma preocupação por parte de todos os envolvidos, em encontrar meios eficazes para garantir a inserção dos PPDs no mercado de trabalho, embora a falta de qualificação ainda seja o maior problema. A criação de Leis similares à Lei 6.297/75 foi apontada como uma grande ajuda às empresas, já que a elas foi imposta essa responsabilidade.(AU)

Why fisheries collapse and what to do about it.

With the collapse of fisheries in many parts of the world causing widespread economic harm, attention is focused on a possible cause and remedy of fishery collapse. Economic theory for managing a renewable resource, such as a fishery, leads to an ecologically unstable equilibrium as difficult to maintain as balancing a marble on top of a dome. A fishery should be managed for ecological stability instead--in the analogy, as easy to maintain as keeping a marble near the base of a bowl. The goal of ecological stability is achieved if the target stock is above that producing maximum sustainable yield and harvested at less than the maximum sustainable yield. The cost of managing for ecological stability, termed "natural insurance," is low if the fishery is sufficiently productive. This cost is shown to pay for itself over the long term in a variable and uncertain environment. An ecologically stable target stock may be attained either with annually variable quotas following current practice or, preferably, through a market mechanism whereby fish are taxed at dockside if caught when the stock was below target and are untaxed otherwise. In this regulatory environment, the goal of maximizing short-term revenue coincides with the goal of ecological stability, thereby also maximizing long-term revenue. This new approach to fishery management is illustrated with the recently collapsed Newfoundland fishing industry. The Newfoundland cod fishery is expected to rebuild to an ecologically stable level in about 9 years and thereafter support an annual harvest of about 75% of the 1981-1990 average.

Efeitos da mecanização agrícola da cultura da cana-de-açúcar nos processos erosivos: dimensionamento de terraços com base na Equação Universal de Perdas de Solo (EUPS)

A cultura da cana-de-açúcar é a segunda maior movimentação econômica na cadeia do agronegócio no Brasil. Gera riquezas através da fabricação de açúcar, etanol e cogeração de energia elétrica, além de outros subprodutos. Considerada fonte de energia renovável, a cana-de- açúcar a princípio tinha sua imagem associada a impactos negativos principalmente devido as queimadas realizadas nas lavouras para colheita manual. Nos últimos anos, baseado em decretos e no Protocolo Agro-ambiental, essa prática vem sendo abolida. Para se manter e até mesmo aumentar o rendimento das colhedoras nos canaviais, os gestores têm adotado práticas para reduzir os terraços agrícolas, com impacto nos sistemas de conservação de solos. Assim, este trabalho teve como objetivo identificar os impactos ambientais provocados pela mecanização agrícola decorrente do mau manejo e dimensionamento dos mecanismos de conservação do solo. Neste estudo também se realizou uma análise à Equação Universal de Perdas de Solo (EUPS), como ferramenta para o dimensionamento de terraços agrícolas. O estudo foi realizado em uma microbacia hidrográfica, denominada Ribeirão da Bocaina, localizada na UGRHI-13 (Tietê - Jacaré). Foi possível identificar a variabilidade amostral do solo para o dimensionamento conservacionista, gerando curvas de nível com Desníveis Verticais (D.V) desuniformes, contrariando a sistemática atual de terraços que respeita cotas múltiplas ou mesmo dimensionamentos empiristas, segundo o conhecimento local e o histórico recente da área. Algumas sugestões também foram feitas afim de torná-la uma ferramenta ainda mais eficiente, considerando condições particulares à cultura da cana-de-açúcar, tais como a influência da palhada, sulcos de plantio e diversos tipos de terraços como meios de controle à erosão. A metodologia foi satisfatória, no que tange a compreensão pelos meios de correlação entre as práticas conservacionistas e modelos de predição de perda de solo, trazendo luz à ciência na interpretação das ferramentas existentes e as lacunas a serem preenchidas.

Motivos de participación de los estudiantes universitarios en actividades físico-deportivas

El objetivo del presente artículo es contribuir al análisis de los motivos de participación de los estudiantes universitarios en la práctica físico-deportiva. También se pretende establecer diferencias por género y conocer dónde practican deporte los universitarios alicantinos. Para ello, se llevó a cabo una investigación no experimental descriptiva en la que participaron 400 alumnos seleccionados por muestreo no probabilístico por cuotas entre todas las facultades de la Universidad de Alicante, a los que se les aplicó el cuestionario MIAFD (Pavón, 2004). Los resultados indican que la mayoría de la población universitaria practicaba actividades físico-deportivas (58.7%). Los motivos más habituales fueron: para estar en forma (85.9%), para liberar energía (80.8%) y para mejorar la salud (78.3%). En cambio, el principal motivo para no practicar actividad física era la falta de tiempo debido a los estudios. Los hombres afirman en mayor medida que las mujeres practicar actividades físico-deportivas para competir y superarse.

Essays on Firm Heterogeneity with Empirical Applications in Economic History and Agricultural Economics

This thesis uses models of firm-heterogeneity to complete empirical analyses in economic history and agricultural economics. In Chapter 2, a theoretical model of firm heterogeneity is used to derive a statistic that summarizes the welfare gains from the introduction of a new technology. The empirical application considers the use of mechanical steam power in the Canadian manufacturing sector during the late nineteenth century. I exploit exogenous variation in geography to estimate several parameters of the model. My results indicate that the use of steam power resulted in a 15.1 percent increase in firm-level productivity and a 3.0-5.2 percent increase in aggregate welfare. Chapter 3 considers various policy alternatives to price ceiling legislation in the market for production quotas in the dairy farming sector in Quebec. I develop a dynamic model of the demand for quotas with farmers that are heterogeneous in their marginal cost of milk production. The econometric analysis uses farm-level data and estimates a parameter of the theoretical model that is required for the counterfactual experiments. The results indicate that the price of quotas could be reduced to the ceiling price through a 4.16 percent expansion of the aggregate supply of quotas, or through moderate trade liberalization of Canadian dairy products. In Chapter 4, I study the relationship between farm-level productivity and participation in the Commercial Export Milk (CEM) program. I use a difference-in-difference research design with inverse propensity weights to test for causality between participation in the CEM program and total factor productivity (TFP). I find a positive correlation between participation in the CEM program and TFP, however I find no statistically significant evidence that the CEM program affected TFP.

Status of quantitative import control over selected U.S. agricultural exports : 16 European countries.

Chiefly tables.

Farm Crisis Act of 1982 [microform] : hearings before the Committee on Agriculture, House of Representatives, Ninety-seventh Congress, second session, on H.R. 6274, May 25 and June 9, 1982.

"Serial no. 97-TTT."