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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Evolução da produtividade da pecuária bovina leiteira em alguns Estados brasileiros: distribuição espacial e análise de convergência para o período de 1974 a 2016 / Evolution of dairy cattle productivity in some Brazilian states: spatial distribution and convergence analysis between 1974 and 2016

Cruz, Alice Aloísia da 04 July 2018 (has links)
Nas últimas décadas, o setor de pecuária bovina leiteira vem passando por diversas modificações influenciadas por redução de número de produtores, mudanças de políticas macroeconômicas e agrícolas e abertura econômica do Brasil. A produção de leite aumentou significativamente ao longo dos anos. Entretanto, mesmo o Brasil sendo um dos maiores produtores do mundo de leite bovino, sua produtividade (medida em litros de leite por vaca) está bem abaixo da dos principais países que operam no mercado. A produtividade da atividade ganha destaque para viabilizar o aumento da produção, suprir a demanda interna e dar maior competitividade ao setor no mercado externo. Diante disso, objetiva-se, através dessa tese, analisar a evolução diferenciada, interestadual e intraestadual, da produtividade da pecuária bovina leiteira nos Estados de Goiás, Minas Gerais, Paraná, Rio Grande do Sul, Santa Catarina e São Paulo, no período de 1974 a 2016, com base em áreas mínimas comparáveis (AMC). Esses Estados representaram 77,5% da produção de leite no Brasil em 2016. Através da análise exploratória de dados espaciais foi identificada a existência de autocorrelação espacial, sendo que a produtividade da pecuária bovina leiteira de uma AMC sofre influência da produtividade das AMC vizinhas. Foram identificados clusters espaciais de produtividade dos tipos Alto-Alto, Baixo-Baixo, Alto-Baixo e Baixo-Alto em todos os Estados considerados ao longo do período em análise. A configuração e localização geográficas desses clusters sofreram alterações nos Estados, refletindo os deslocamentos da produção ocorridos. Posteriomente, passou-se para a análise de convergência no intuito de identificar se está ocorrendo redução na diferença entre as produtividades da pecuária bovina leiteira entre as AMC e se os efeitos espaciais contribuem para as convergências absoluta e condicional. Para tanto, fez-se uso da econometria espacial. Para a análise de convergência condicional foram incorporadas variáveis de primeira e segunda natureza, propostas na Nova Geografia Econômica. Tanto a análise da convergência absoluta quanto a da convergência condicional confirmam a hipótese de existência de convergência e demonstram o efeito de transbordamento, ou seja, os choques ocorridos em uma AMC refletem nas AMC vizinhas. Entretanto, a velocidade de convergência foi baixa nas duas situações, indicando que a redução das diferenças de produtividade está ocorrendo de forma muito lenta. A análise de convergência condicional mostrou que as características iniciais das AMC influenciam para qual ponto estacionário a produtividade da pecuária bovina leiteira irá convergir, sendo que as variáveis distância da capital, pluviosidade, população, Produto Interno Bruto, crédito rural de investimento para pecuária e área com culturas tiveram influência diferenciada nos Estados no processo de convergência da produtividade tanto no período analisado como um todo como nos subperíodos considerados na tese. / In recent decades, the dairy cattle sector has undergone changes influenced by decline in the number of producers, changes in government macroeconomic and agricultural policies, and the country\'s economic opening. Milk production has increased significantly over the years. Brazil is one of the world\'s largest producers of bovine milk; however, its productivity (measured in liters of milk per cow) is still lower than that found in other major milk producing countries. The productivity of the activity is important to enable the increase of production, supplying domestic demand and giving greater competitiveness in the external market. The objective of this thesis is to analyze the differentiated interstate and intrastate evolution of dairy cattle productivity in the Brazilian states of Goiás, Minas Gerais, Paraná, Rio Grande do Sul, Santa Catarina and São Paulo from 1974 through 2016 based on minimum comparable areas (MCA). These states accounted for 77.5% of Brazil\'s milk production in 2016. Exploratory spatial data analysis confirmed the existence of spatial autocorrelation indicting that dairy cattle productivity in an MCA is influenced by the productivity in neighboring MCA. Over the analyzed period, High-Low, Low-Low, High-Low, and Low-High productivity spatial clusters were identified in all studied states. The configuration and geographic location of these clusters underwent changes during the study period, reflecting production displacement. Convergence analysis using spatial econometrics was carried out to determine if the differences in dairy cattle productiveness among MCA were reduced over the period and if spatial effects contributed to any absolute or conditional convergence. First and second nature variables were employed for the analysis of conditional convergence, as proposed by the New Economic Geography. Both convergence analyses, absolute and conditional, confirmed the convergence hypothesis and demonstrated the overflow effect, in that shocks occurring in one MCA were reflected in neighboring MCA. However, the speed of convergence was low in both situations, indicating that productivity differences among the MCA were being reduced very slowly. The analysis of conditional convergence showed that the productivity of dairy farming in different MCA will tend to converge at the same stationary point if the MCA show similar initial values for selected variables. The selected variables are average yearly rainfall, population size, gross domestic product, and investment credit for livestock and rangeland acquisitions and are intended to represent conditions in each MCA and state at a specific time. Each variable had a differentiated influence on the process of productivity convergence over the period and subperiods considered in this thesis.
72

On-line control of glucose feeding in an Escherichia coli fed-batch cultivation expressing a recombinant protein.

Gustavsson, Robert January 2011 (has links)
Soft sensors have been suggested as potent tools for on-line estimations of critical bioprocess variables to be able to control the biological process in an as high extent as possible. The formation of inhibitory by-products in the form of organic acids, caused by an overflow of glucose, is a problem in most bioprocesses expressing recombinant proteins.    In this project a new method of controlling the glucose feeding in an Escherichia coli fed-batch cultivation expressing the green fluorescent protein (GFP) was investigated. The new controller system implemented in the software controlled the feed rate based on on-line HPLC measurements of the concentration of organic acids.      The results showed that the controller managed to down-regulate the inhibitory organic acids to a low level as it tried to keep the glucose uptake rate at an optimum for maximum cell growth. The results suggested that the controller could be a powerful tool to create a more secure reproducibility and to generate high product yields in recombinant protein productions.
73

Dimensionering av åtgärder i kombinerade ledningssystem vid ökad spillvattenbelastning / Designing of measures in combined sewer systems at increased sanitary sewage load

Näsman Melander, Emelie January 2012 (has links)
Ett allt vanligare uppdrag inom hydraulisk modellering är att undersöka hur nya bostads- och handelsområden påverkar statusen för äldre befintliga ledningsnät. I nya områden anläggs nästan uteslutande separatsystem och eftersom nya områden oftast uppförs utanför den befintliga bebyggelsen måste spillvattnet från dessa områden transporteras genom det befintliga avloppsnätet, vilket kan vara helt eller delvis kombinerat. I stadsdelen Hjorthagen i Stockholm planeras 5000 nya lägenheter att byggas och spillvattenflödet från dessa skall anslutas uppströms det befintliga kombinerade ledningsnätet i området. Examensarbetet har gått ut på att undersöka hur det kombinerade ledningssystemet påverkas av den tillkommande spillvattenbelastningen. Syftet var att undersöka hur den dimensionerande spillvattenavrinningen påverkar de åtgärder och kostnader som behövs för att få det utökade ledningsnätet att fungera, samt att utreda behovet av ytterligare anpassningar av ledningsnätet inför framtida klimatförändringar. Vid beräkning av bräddvolymer simuleras vanligen spillvattenavrinningen från medeldygnsförbrukning av vatten. I studien har det även ingått att undersöka om detta sätt ger lägre bräddvolymer jämfört med att variera vattenförbrukningen med ett veckomönster. Med modelleringsprogrammet MIKE Urban undersöktes tre fall av dimensionerande spillvattenflöde från det tillkommande området i Hjorthagen. Olika stor säkerhetsmarginal användes vid dimensioneringen. I alla tre fallen fick det tillkommande spillvattenflödet kapaciteten i det kombinerade ledningssystemet att överskridas redan vid torrväder, med bräddning som följd. Undersökningen visade att ju högre säkerhetsmarginal dimensioneringen innebar desto mer omfattande blev de åtgärder som krävdes för att få bräddningen att upphöra. Fallet med störst säkerhetsmarginal krävde ett utjämningsmagasin på 142 m3 och att dimensionen på 670 m ledning ökades från 400 mm till 600 mm med en uppskattad åtgärdskostnad på omkring nio miljoner kronor. De åtgärder som krävdes för att undvika bräddning vid torrväder var i alla tre fallen tillräckliga för att både minska bräddningen vid regnväder och för att klimatanpassa ledningsnätet. I de fall som undersöktes kunde ingen trend ses som visade att simulering av dag- och spillvattenavrinning, utan veckovariationer i vattenförbrukningen, skulle ge för låga bräddvolymer. / An increasingly common assignment in hydraulic modeling is to investigate how sewage from new residential and commercial areas affect the status of existing sewer systems. In new areas the sewer systems are constructed to operate separately from storm drains and since new areas often are founded in the outskirt of existing areas the sanitary sewage from these areas must be transported through the older existing sewer system, which can be completely or partly combined. In the district of Hjorthagen in Stockholm 5,000 new apartments are planned to be built and sewage from these must be connected upstream of existing combined sewer system in the area. The purpose of this master thesis was to investigate how combined sewer system is affected by additional sewage load. The aim was to investigate how the choice of design sewage flow affects the measures and costs necessary to get the extended sewer system to function, and to consider the need for further adjustments to future climate change. When calculating volumes of combined sewer overflow the sewage flow usually is simulated as discharge from average water use. One objective with this thesis was to investigate whether this method gave lower volumes of combined sewer overflow as compared to using a weekly pattern. By using the modeling program MIKE Urban three choices of design sewage flow, from the new area in Hjorthagen, were investigated. The margin of safety when designing the sewage flow was increased in each case. The results showed that the capacity of the combined sewer system was exceeded during dry weather, with overflow as a result. The investigation showed that the higher margin of safety used the more extensive measures was needed. The greatest margin of safety required a storage basin of 142 m3 and that the dimension of 670 m of pipes was increased. To stop the overflow at dry weather the measures required in each case were sufficient to both reduce overflow during wet weather and to adjust the sewer system to future climate. Simulating the rainfall runoff and sewage flow, without weekly variations in water consumption did not underestimate the volumes of combined sewer overflow compared to varying the water use.
74

Bräddvattenstudie i Håbo kommun : Patogenspridning från lokalt reningsverk i recipient / Study of sewage water overflow in Håbo municipality : Spreading of pathogens from the local treatment plant to recipient

Johansson, Tobias January 2015 (has links)
Klimatscenarier framtagna av SMHI visar bland annat på att nederbördsmängden kommer att öka i stora delar av Sverige. En ökad nederbördsmängd leder till att flöden i vattendrag och spillvattenledningar ökar, som i sin tur kan leda till att oönskade ämnen förorenar viktiga naturresurser så som dricksvattentäkter. Den största risken för mikrobiella föroreningar i vattentäkter och vattendrag kommer från Sveriges reningsverk, främst till följd av att reningsverkens flödeskapacitet överstigs på grund av kraftiga regn. Vid kraftiga regn riskerar reningsverk att bräddas, vilket leder till att ofullständigt renat spillvatten leds ut till sjöar.   Bålsta reningsverk, Håbo kommun, bräddas ibland på grund av höga flöden. Det otillräckligt renade spillvattnet leds då ut till reningsverkets utsläppspunkt söder om Bålsta stad i Norra Björkfjärden. Mindre än två kilometer ifrån reningsverkets utsläppspunkt ligger Bålsta vattenverks råvattenintag. Det är således av intresse att undersöka om vattenverkets råvattenintag påverkas av en bräddning. Utöver vattenverket ligger flera populära badplatser i närheten av reningsverkets utsläppspunkt.   Syftet med examensarbetet var att studera hur en bräddning av orenat spillvatten sprids i Mälaren under sommarens badsäsong, samt att identifiera vid vilka vind- och flödesförhållanden badplatserna och råvattentäkten har störst risk att förorenas. Syftet var även att studera hur en ökad nederbördsmängd påverkar delar av Bålsta reningsverks spillvattenledningsnät. För att nå examensarbetets syfte användes spridningsmodellen Delft3D samt ledningsnätmodellen MIKE-Urban. På grund av otillräcklig data om bland annat Bålsta reningsverks spillvattenledningsnät erhölls inget tillförlitligt resultat från MIKE-Urban modelleringen. Istället sammanställdes de saknade data om reningsverkets spillvattenledningsnät vilket resulterade i förslag om kompletterande åtgärder för att underlätta kommande spillvattenmodelleringar.    Resultat från spridningssimuleringen tydde på att ingen av de studerade platserna överskrider värden för utmärkt badvattenkvalitet enligt EU:s badvattendirektiv vid medelvindhastighet samt ett utsläpp av 77 m3 orenat spillvatten. En bräddning av 77 m3 orenat spillvatten baserades på reningsverkets bräddningsvolymer från år 2010. För badplatserna ansågs det fördelaktigt att en bräddning sker under vindstilla förhållanden till följd av begränsad omblandning mellan Mälarens temperaturskiktning. Vid ett två dygn långt utsläpp av totalt 5 000 m3 orenat spillvatten med fem sekundmeters vind erhöll majoriteten av badplatserna för höga patogenvärden. Reningsverkets personal bör i sådana situationer gå ut med allmänna varningar för badande i Norra Björkfjärden. / Climate change scenarios conducted by SMHI indicate increasing precipitation in most parts of Sweden. Such increases will lead to bigger flows in rivers and sewer networks, which in turn may lead to leakage of unwanted substances such as contagious microorganisms to drinking water supplies. The single largest risk of lake contamination is from sewage water treatment plants, mostly due to overflow of wastewater. High precipitation may flood the treatment plant causing untreated water to leak out and into surrounding lakes.   Bålsta treatment plant, in Håbo municipality, has overflow issues in periods with high precipitation, which lead to leakage of inadequately treated wastewater and thus local contamination in Lake Mälaren. Less than two kilometers from the release point of Bålsta treatment plant, Bålsta drinking water plant has its intake of raw water. Hence it is of great interest to study the dispersal of Bålsta treatment plant’s wastewater in Lake Mälaren to prevent unwanted human exposure to contagious microorganisms. Håbo municipality also has popular swimming spots close to the treatment plant’s outlet.   The aim of this study is to examine the pathogenic impact that an overflow of Bålsta treatment plant in summer time has on Bålsta drinking water plant and bathing spots. The study hoped to identify the conditions where certain places of interest were to be contaminated. In addition, the aim was to investigate the changes of sewage flow due to an increased precipitation. Two models were used to reach the aforementioned aims: (1.) a hydrodynamic model (Delft3D) to study the spread of wastewater following an overflow and (2.) an urban water model (MIKE–Urban) to study the total amount of sewage flow.   Due to insufficient data concerning Bålsta’s sewage system, simulations from MIKE–Urban were unable to provide reliable results. Large parts of the sewage network had missing data regarding pipe dimensions, positioning and material, which resulted in a model with little precision. Instead of providing unreliable results, the study resulted in recommendations for further data collecting to help future investigations of Bålsta’s sewage system.   With low overflows of untreated water, Delft3D modeling showed that none of the places of interest had pathogen levels that exceeded the European Union’s Bathwater quality directive when simulated with mean values of wind, treated wastewater flow and wind direction. When extreme amounts of overflow were simulated in strong winds, five of seven places of interest were unfit for bathing according to the directive. In case of an overflow of more than the simulated outflow of 77 m3 untreated wastewater, the operators of Bålsta’s treatment plant need to perform actions to prevent human exposure.
75

Evaluation of on-line cell viability and L-lactate measurements in soft sensor for mammalian cell cultures

Reissig, Alexander January 2014 (has links)
Increasing demand on more effective cell culture reactors has driven optimization works to increase output of products. This has led to development of soft sensors that uses mathematical formulas to increase the available information for the parameters during runs. In the project two parameters was evaluated for use in such a soft sensor, viability by measuring on-line capacitance with Aber probe and L-lactate production using BioSenz apparatus. To determine how well these could be used both were used on batch reactors measuring on a mouse-mouse B cell hybridoma culture which produced IgG1. On-line measurements were performed by probes which measured directly on the cell suspension or withdrew sterile sample from the reactor. Measuring viability gave results with low error, which can be concluded to the variation in reference cell count, but it could not be determined if measuring L-lactate production with BioSenz works in reactors of this size. More work needs to be done on other types of reactors, like fed-batch or perfusion, or lower working volumes.
76

The effects of threshold nonlinearities on the transformation of rainfall to runoff to floods in a lake dominated catchment system

Kusumastuti, Dyah Indriana January 2007 (has links)
[Truncated abstract] Runoff generation behaviour and flooding in a lake dominated catchment are nonlinear, threshold-driven processes that result from the interactions between climate and various catchment characteristics. A complicating feature of the rainfall to runoff transformation, which may have implications for the flood frequency, is that the various surface and subsurface flow pathways are dynamic, heterogeneous and highly nonlinear, consisting of distinct thresholds. To understand the impact of threshold nonlinearities on the rainfall-runoff transformation in such catchments, a systematic examination was carried out to investigate runoff generation behaviour of the catchment itself, the overflow behaviour of a lake in combination with the catchment draining into it, as well as the lake organisation within a lake chain network. Three storage based thresholds were considered: the catchment field capacity storage governing catchment subsurface stormflow, total storage capacity governing catchment surface runoff, and lake storage capacity governing lake-overflow. ... Through these investigations, this thesis has provided valuable insights into the process controls of lake-overflow events and the associated flood frequency behaviour in lake dominated catchments. In particular, the relative roles of climate, soil depth, the soil?s drainage capacity, as well as the relative geometry of the lake vis a vis the contributing catchment, in the determination of the dynamic characteristics of lake-overflow events and associated flood frequency behaviour have been highlighted. In addition, the importance of lake organization, as expressed in terms of the average ratio of catchment area to lake area and the spatial variability of this ratio from upstream to downstream, and their impact upon connectivity and flood frequency have also been explored. The outcomes of this study highlight the importance of thresholds governing flood frequency, and provide insights into the complex interactions between rainfall variability and the various threshold nonlinearities in the rainfall-runoff process, which are shown to have a significant impact on the resulting flood frequency curves. The improved understanding of these process controls will be useful in assisting the 1 management of the catchment-lake system in the study region, and in regions elsewhere. In particular, the outcome of this study can provide guidance towards the adoption of various management strategies for lake chain systems by illustrating the effects of potential flow interruption and retardation as ways to assist in flood prevention and mitigation, whether it is aimed at decreasing the frequency of occurrence of lake overflows, or merely decreasing the flow magnitude for a given return period.
77

Produção de leite no Rio Grande do Sul: a distribuição espacial e a relação de dependência entre os municípios / Milk production in Rio Grande do Sul: a spatial distribution and dependency ratio between municipalities

Schumacher, Gabriela 25 February 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The study analyzes the spatial distribution of milk production in the municipalities and the relation of dependence between them in Rio Grande do Sul in 2010. The research is characterized as quantitative and ex post facto, and the statistical method used in the analysis. The data collection was made from the data query side of 496 municipalities of the State of Rio Grande do Sul for the year 2010. Initially, we calculated the location quotient to identify the municipalities and specialized after we used spatial econometric techniques to identify whether there are spillover between them. The results show that in 2010 the Rio Grande do Sul 128 municipalities had specialized in the production of milk, the top ten are located in the regions of the Northwest, Northeast and Mid-East. The same result was found by exploratory spatial data analysis (ESDA), which highlighted how important these poles milk production. The Moran's I statistic indicated that there is a positive spatial autocorrelation for the gross value of milk production, suggesting the existence of spatial dependence. The econometric tests have confirmed from the spatial lag model that overflow exists between municipalities. This effect was best explained by variable capital, labor, pasture area, electricity, education, average rainfall, paved and unpaved roads. / O estudo analisa a distribuição espacial da produção de leite nos municípios e a relação de dependência entre eles no Rio Grande do Sul no ano de 2010. A pesquisa se caracteriza como quantitativa e ex post facto, e utilizada o método estatístico na análise. A coleta de dados foi feita a partir da consulta a dados secundários dos 496 municípios do Estado do Rio Grande do Sul para o ano de 2010. Inicialmente, calculou-se o Quociente Locacional para identificar os municípios especializados e após utilizou-se técnicas de econometria espacial para identificar se há transbordamento entre eles. Os resultados mostram que em 2010 o Rio Grande do Sul possuía 140 municípios especializados na produção de leite, sendo que eles localizam-se nas mesorregiões Noroeste, Nordeste e Centro-oriental. O mesmo resultado foi encontrado mediante a análise exploratória de dados espaciais (AEDE), que destacou esses como os importantes polos de produção de leite. A estatística I de Moran indicou que existe uma autocorrelação espacial positiva para o valor bruto da produção de leite, sugerindo a existência de dependência espacial. Os testes econométricos confirmaram a partir do modelo de defasagem espacial que existe transbordamento entre os municípios. Esse efeito foi melhor explicado pelas variáveis capital, trabalho, área de pastagem, energia elétrica, educação, precipitação média, rodovias pavimentadas e rodovias não pavimentadas.
78

Software Security Analysis : Managing source code audit

Persson, Daniel, Baca, Dejan January 2004 (has links)
Software users have become more conscious of security. More people have access to Internet and huge databases of security exploits. To make secure products, software developers must acknowledge this threat and take action. A first step is to perform a software security analysis. The software security analysis was performed using automatic auditing tools. An experimental environment was constructed to check if the findings were exploitable or not. Open source projects were used as reference to learn what patterns to search for. The results of the investigation show the differences in the automatic auditing tools used. Common types of security threats found in the product have been presented. Four different types of software security exploits have also been presented. The discussion presents the effectiveness of the automatic tools for auditing software. A comparison between the security in the examined product and the open source project Apache is presented. Furthermore, the incorporation of the software security analysis into the development process, and the results and cost of the security analysis is discussed. Finally some conclusions were drawn.
79

An Exploration of Information Inadequacy: Instances that Cause the Lack of Needed Information

Kajtazi, Miranda January 2011 (has links)
Information is one of the most essential resources in our contemporary societies, as it guideshuman thinking, planning and subsequent actions, which in turn generates consequencesthat are desired or not. The Lehman Brothers bankruptcy in 2008, the tsunami in Indonesiain 2004, the Space Shuttle Challenger destruction in 1986 are just three instances ofdramatic situations, emerging continuously, where information plays a crucial role. Thisstudy investigates the phenomenon of the lack of needed information, predominantlyexperienced with difficulties in human, social and industrial affairs. Consequently, thechallenge is to understand why such situations emerge. Two approaches are utilized toexplore this challenge using an interpretivist tradition. The first is a hermeneutic approach,the second a grounded theory approach. The first approach – theoretically oriented –investigates numerous theoretical bodies, selected with the assumption that they can explainthe addressed challenge. The results show that there are no comprehensive theoreticalbodies that can fully account for the phenomenon of the lack of needed information.Furthermore, there is no consensus on what “information” is – the very core of thechallenge, which gave the foundations for a formulation of an alternative notion ofinformation and is instrumental for the present investigation. Thus, no a priori theory isused to guide the empirical investigation. The second approach – empirically oriented –investigates fifty empirical cases, where the lack of needed information is clearly manifested.The results present an initial outline for a possible future theory of information inadequacy,constituted by the dichotomy of information-lack and information-overflow. Informationlackis dominated by: “information is non-existent”, “information is insufficient”, “information is censored” and “information is undelivered”. Whereas, information-overflow isdominated by: “information is ambiguous”, “information is redundant”, “information isirrelevant” and “information is undervalued”. The two main dichotomous characteristics andtheir interrelations result in patterns of various information inadequacies. The keyconclusion of the present study is that while dramatic situations are increasing everyday,there is as yet no theoretical body designed to comprehensively account for the phenomenonin context; only partial accounts are found. Thus, the empirical investigation suggests thatthe phenomenon of the lack of needed information seems to emerge because of diversefactors, ranging from political and cultural structures, through human individualcapabilities, and ending with procedural and technological artefacts. This study advocatesthat further research is needed to fully account for and explain instances of the lack ofneeded information, and that such an account requires an innovative and interdisciplinary focus.
80

Evolução da produtividade da pecuária bovina leiteira em alguns Estados brasileiros: distribuição espacial e análise de convergência para o período de 1974 a 2016 / Evolution of dairy cattle productivity in some Brazilian states: spatial distribution and convergence analysis between 1974 and 2016

Alice Aloísia da Cruz 04 July 2018 (has links)
Nas últimas décadas, o setor de pecuária bovina leiteira vem passando por diversas modificações influenciadas por redução de número de produtores, mudanças de políticas macroeconômicas e agrícolas e abertura econômica do Brasil. A produção de leite aumentou significativamente ao longo dos anos. Entretanto, mesmo o Brasil sendo um dos maiores produtores do mundo de leite bovino, sua produtividade (medida em litros de leite por vaca) está bem abaixo da dos principais países que operam no mercado. A produtividade da atividade ganha destaque para viabilizar o aumento da produção, suprir a demanda interna e dar maior competitividade ao setor no mercado externo. Diante disso, objetiva-se, através dessa tese, analisar a evolução diferenciada, interestadual e intraestadual, da produtividade da pecuária bovina leiteira nos Estados de Goiás, Minas Gerais, Paraná, Rio Grande do Sul, Santa Catarina e São Paulo, no período de 1974 a 2016, com base em áreas mínimas comparáveis (AMC). Esses Estados representaram 77,5% da produção de leite no Brasil em 2016. Através da análise exploratória de dados espaciais foi identificada a existência de autocorrelação espacial, sendo que a produtividade da pecuária bovina leiteira de uma AMC sofre influência da produtividade das AMC vizinhas. Foram identificados clusters espaciais de produtividade dos tipos Alto-Alto, Baixo-Baixo, Alto-Baixo e Baixo-Alto em todos os Estados considerados ao longo do período em análise. A configuração e localização geográficas desses clusters sofreram alterações nos Estados, refletindo os deslocamentos da produção ocorridos. Posteriomente, passou-se para a análise de convergência no intuito de identificar se está ocorrendo redução na diferença entre as produtividades da pecuária bovina leiteira entre as AMC e se os efeitos espaciais contribuem para as convergências absoluta e condicional. Para tanto, fez-se uso da econometria espacial. Para a análise de convergência condicional foram incorporadas variáveis de primeira e segunda natureza, propostas na Nova Geografia Econômica. Tanto a análise da convergência absoluta quanto a da convergência condicional confirmam a hipótese de existência de convergência e demonstram o efeito de transbordamento, ou seja, os choques ocorridos em uma AMC refletem nas AMC vizinhas. Entretanto, a velocidade de convergência foi baixa nas duas situações, indicando que a redução das diferenças de produtividade está ocorrendo de forma muito lenta. A análise de convergência condicional mostrou que as características iniciais das AMC influenciam para qual ponto estacionário a produtividade da pecuária bovina leiteira irá convergir, sendo que as variáveis distância da capital, pluviosidade, população, Produto Interno Bruto, crédito rural de investimento para pecuária e área com culturas tiveram influência diferenciada nos Estados no processo de convergência da produtividade tanto no período analisado como um todo como nos subperíodos considerados na tese. / In recent decades, the dairy cattle sector has undergone changes influenced by decline in the number of producers, changes in government macroeconomic and agricultural policies, and the country\'s economic opening. Milk production has increased significantly over the years. Brazil is one of the world\'s largest producers of bovine milk; however, its productivity (measured in liters of milk per cow) is still lower than that found in other major milk producing countries. The productivity of the activity is important to enable the increase of production, supplying domestic demand and giving greater competitiveness in the external market. The objective of this thesis is to analyze the differentiated interstate and intrastate evolution of dairy cattle productivity in the Brazilian states of Goiás, Minas Gerais, Paraná, Rio Grande do Sul, Santa Catarina and São Paulo from 1974 through 2016 based on minimum comparable areas (MCA). These states accounted for 77.5% of Brazil\'s milk production in 2016. Exploratory spatial data analysis confirmed the existence of spatial autocorrelation indicting that dairy cattle productivity in an MCA is influenced by the productivity in neighboring MCA. Over the analyzed period, High-Low, Low-Low, High-Low, and Low-High productivity spatial clusters were identified in all studied states. The configuration and geographic location of these clusters underwent changes during the study period, reflecting production displacement. Convergence analysis using spatial econometrics was carried out to determine if the differences in dairy cattle productiveness among MCA were reduced over the period and if spatial effects contributed to any absolute or conditional convergence. First and second nature variables were employed for the analysis of conditional convergence, as proposed by the New Economic Geography. Both convergence analyses, absolute and conditional, confirmed the convergence hypothesis and demonstrated the overflow effect, in that shocks occurring in one MCA were reflected in neighboring MCA. However, the speed of convergence was low in both situations, indicating that productivity differences among the MCA were being reduced very slowly. The analysis of conditional convergence showed that the productivity of dairy farming in different MCA will tend to converge at the same stationary point if the MCA show similar initial values for selected variables. The selected variables are average yearly rainfall, population size, gross domestic product, and investment credit for livestock and rangeland acquisitions and are intended to represent conditions in each MCA and state at a specific time. Each variable had a differentiated influence on the process of productivity convergence over the period and subperiods considered in this thesis.

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