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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.
161

Economic Development and Forest Cover: Evidence from Satellite Data

Crespo Cuaresma, Jesus, Danylo, Olha, Fritz, Steffen, McCallum, Ian, Obersteiner, Michael, See, Linda 01 1900 (has links) (PDF)
We use satellite data on forest cover along national borders in order to study the determinants of deforestation differences across countries. We combine the forest cover information with data on homogeneous response units, which allow us to control for cross-country geoclimatic differences when assessing the drivers of deforestation. Income per capita appears to be the most robust determinant of differences in cross-border forest cover and our results present evidence of the existence of decreasing effects of income on forest cover as economic development progresses.(authors' abstract) / Series: Department of Economics Working Paper Series
162

Housework over the course of relationships: Gender ideology, resources, and the division of housework from a growth curve perspective

Nitsche, Natalie, Grunow, Daniela January 2016 (has links) (PDF)
In the 21st century, the division of housework remains gendered, with women on average still spending more time doing chores than their male partners. While research has studied why this phenomenon is so persistent, few studies have yet been able to assess the effect of gender ideology and socio-economic resources at the same time, usually due to data restrictions. We use data from the pairfam, a new and innovative German panel study, in order to test the effect of absolute and relative resources as well as his and her gender ideology on the division of housework. We employ a life course perspective and analyze trajectories of couples' housework division over time, using multi-level random effects growth curve models. We find that an egalitarian gender ideology of both him and her significantly predicts more egalitarian division-trajectories, while neither absolute nor relative resources appear to have an effect on the division of housework over time. Furthermore, our results expand the literature by investigating how these processes differ among childless couples and couples who experience the first birth.
163

Analýza růstové schopnosti krůt ve vybraném podniku

JANDOVÁ, Lucie January 2019 (has links)
The aim of the thesis was to evaluate the feeding parameters of hybrid B.U.T. 6 at selected farm. Six batches of tom turkeys were evaluated in this study. The growth intensity analysis was performed based on weekly weighing. The average live weight was 21.83 kg at the age of 21 weeks. The highest value was in the 3rd batch (22.18 kg) and the lowest value was in the 2nd and the 6th batch (21.62 kg). In comparison with the "Management guide", the differences in average weight from the 5th week of age to the end of fattening were evaluated as statistically significant. The average feed conversion ratio was registered 2.73 kg. The highest feed conversion was in the 1st batch (2.82 kg) and the lowest was in the 5th batch (2.62 kg). The average inflection point was reached in the 14th week (12.1 kg). First the inflection point was achieved in the 1st and 2nd batch (13.6 weeks; 11.7 kg and 13.7 weeks; 11.4 kg) and at the latest in the 4th batch (15.5 weeks; 13.6 kg). The average maximum daily gain was reached 203.1 g (13.6 weeks). The highest was in the 3rd batch (204.9 g; 13.6 weeks) and the lowest was in the 4th batch (195.3 g; 14.3 weeks). The average mortality rate was found 6.39%. The highest mortality rate was in the 6th batch (8.44%; 858 pcs) and the lowest was in the 4th batch (4.50%; 457 pcs).
164

Rethinking the Phillips Curve: A Study of Recent Inflation Dynamics in the G-7

Cloutier, Mark Andrew January 2012 (has links)
Thesis advisor: Robert Murphy / A study of recent inflation dynamics in the G-7, this paper discusses a problem with the Phillips curve which arose during the Great Recession (2008-2011). We find that work with time-varying slope, expectation anchoring, and core inflation can correct for the under-predictions that develop in the Phillips Curve during the recession, improving its accuracy throughout the G-7. / Thesis (BA) — Boston College, 2012. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Economics Honors Program. / Discipline: Economics.
165

Implications of a modern phillips curve

Barnard, Russell January 2017 (has links)
Thesis advisor: Robert Murphey / This paper demonstrates that a linear Phillips Curve has neither theoretical nor empirical justification. I first alter the traditional linear model specification to allow for non-linearity between inflation and unemployment. I show that these non-linear models produce greater R2’s than similar linear versions. I provide theoretical justification for the non-linear models and demonstrate why the theoretical reasoning for linear models is flawed. Finally, by introducing the natural rate of unemployment as a separate independent variable, I increase the explanatory power of the model. I allow the natural rate’s marginal effect on inflation to vary with time and suggest a theoretical framework that supports this final model. I conclude that non-linearity and therefore convexity between inflation and unemployment is the correct framework under any time period for Phillips Curve analysis and application. / Thesis (BA) — Boston College, 2017. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Economics.
166

Elliptic Curves and their Applications to Cryptography

Bathgate, Jonathan January 2007 (has links)
Thesis advisor: Benjamin Howard / In the last twenty years, Elliptic Curve Cryptography has become a standard for the transmission of secure data. The purpose of my thesis is to develop the necessary theory for the implementation of elliptic curve cryptosystems, using elementary number theory, abstract algebra, and geometry. This theory is based on developing formulas for adding rational points on an elliptic curve. The set of rational points on an elliptic curve form a group over the addition law as it is defined. Using the group law, my study continues into computing the torsion subgroup of an elliptic curve and considering elliptic curves over finite fields. With a brief introduction to cryptography and the theory developed in the early chapters, my thesis culminates in the explanation and implementation of three elliptic curve cryptosystems in the Java programming language. / Thesis (BA) — Boston College, 2007. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Mathematics. / Discipline: College Honors Program.
167

Contribuição ao estabelecimento do comprimento desejável da espiral de transição em rodovias rurais e urbanas. / Contribution to the establishment of the desirable length of the spiral transition in highways and streets.

Arakawa, Maki 21 November 2012 (has links)
A curva de transição apresenta um raio de curvatura variando de um valor infinito no fim da tangente até um valor igual ao raio da curva circular no final da curva de transição. Nos projetos rodoviários, o tipo de curva mais utilizado é a clotóide, pois esta corresponde à trajetória descrita pelo veículo, com uma velocidade constante e o volante girando com velocidade angular constante. Consequentemente, é uma situação em que não requer esforço do motorista, proporciona uma trajetória mais natural e um aumento/redução da aceleração radial de um veículo de forma gradual. O presente trabalho admite que o comprimento desejável da espiral de transição em rodovias rurais e urbanas, baseado na recomendação da AASHTO (2011), é igual à distância correspondente a um tempo de percurso de 2 segundos ao longo da via à velocidade de projeto. É recomendável que o comprimento considerado como desejável seja suficiente para se realizar a transição da superelevação, e por outro lado, deve ser menor que o comprimento crítico de hidroplanagem, ou seja, comprimento a partir do qual o veículo passa a perder contato do pneu/pavimento em uma pista coberta com lâmina dágua, a uma velocidade crítica. Visto que os manuais brasileiros não introduzem a hidroplanagem como um dos fatores considerados para estabelecer estes comprimentos, pretende-se desenvolver uma ferramenta de trabalho que auxilia na determinação do comprimento desejável da espiral de transição, possibilitando uma análise do risco de ocorrência do fenômeno da hidroplanagem. No estudo de caso, são calculados comprimentos da espiral de transição de três curvas, onde serão feitas também simulações com diferentes parâmetros para analisar as situações críticas de hidroplanagem. Os resultados obtidos demonstram que comprimentos muito longos da espiral de transição, combinado com uma declividade longitudinal muito baixa pode aumentar o risco de hidroplanagem. / The transition curve has a radius of curvature varying from infinity at the end of the tangent to a value equal to the radius of the circular arc at the end of the transition curve. In highway design, clothoid is the most commonly used spiral type because it corresponds to the path described by the vehicle, with a constant speed and the less need for steering. Consequently, it\'s a situation that doesn\'t require driver effort, providing a more natural path and a gradual increase / reduction of the centrifugal force of a vehicle. Based on AASHTO (2011)\'s recommendation, this study establishes that the desired length of the spiral transition in highways and streets is equal to the distance traveled in 2 seconds in the design speed. It\'s recommended that the spiral length considered as desirable is sufficient to perform the superelevation runoff and on the other hand, should be shorter than the critical length of hydroplaning, in other words, it\'s a phenomenon caused by the increase of the water film above the contact pressure of tire and road. Since the manuals do not introduce hydroplaning as one of the criteria considered in establishing these lengths, a tool will be developed to define the desirable spiral length, allowing an analysis of the risk of hydroplaning. In the study, the lengths of three spiral transition curves are calculated; furthermore simulations with different parameters of these three curves are also calculated to analyze critical situations of hydroplaning. The results demonstrate that longer lengths of spiral transition combined with lower grades may increase the risk of hydroplaning.
168

Influência de técnicas de instrumentação dos canais radiculares na qualidade dos preparos realizados por alunos de graduação / Shape ability of different root canal instrumentation techniques when performed by undergraduate students

Jacob, Thaís Nejm 12 February 2019 (has links)
Durante preparo cirúrgico endodôntico, a modelagem centralizada e com menor tempo de trabalho possível são objetivos de qualquer operador, independentemente da sua experiência ou da técnica utilizada. Os desafios encontrados para a realização da modelagem ideal pode incluir dificuldades como a presença de curvaturas no canal e ainda, a inexperiência de quem a realiza. Os sistemas de lima única tem apresentado resultados favoráveis no que se refere à sua qualidade de preparo e seu tempo de trabalho. Ademais, esta técnica possui simplicidade no seu \"modus-operandi\", encorajando estudos que observem a sua aplicação no inicio da prática endodôntica. Afim de se observar o comportamento dos sistemas de lima única neste nicho de operadores, foram selecionados alunos de graduação. Propondo-se avaliar 12 operadores diferentes, foram utilizados 48 canais simulados curvos (Dentsply Sirona, Ballaigues, Suiça), onde cada operador instrumentou: 1 com técnica manual acorde Machado, 1 com sistema Wave One Gold Primary (Dentsply Sirona, Ballaigues, Suiça), 1 com sistema ProDesign Logic 25.06 (Easy Equip.Odontológicos, Belo Horizonte, Brasil) em movimento rotatório contínuo e 1 com sistema ProDesign Logic 25.06 (Easy Equip.Odontológicos, Belo Horizonte, Brasil) em movimento reciprocante (n=48). A modelagem produzida após a instrumentação foi avaliada pelos os critérios centricidade de preparo e tempo de trabalho. Quanto à qualidade do preparo, através de imagens sobrepostas e com auxílio do programa Adobe Photoshop CC 2018 (Adobe Systems, San Jose, CA), os valores de centricidade foram obtidos nas alturas de 1 à 9mm do canal simulado. O tempo de trabalho foi cronometrado excluindo-se a troca entre instrumentos e a irrigação do canal. Para a análise comparativa do tempo de trabalho entre os grupos, foi utilizado o teste Anova 1 fator com correção e pós-teste de Tukey para as múltiplas comparações. A centricidade dos preparos foi analisada através do teste de o Teste Kruskal-Wallis com o pós-teste de Dunn para as comparações múltiplas. Como resultado, o grupo Prodesign Logic em movimento rotatório (ROL) apresentou o menor tempo de instrumentação, seguido do grupo Wave One Gold (WOG) e, apresentando os maiores índices, os grupos Prodesign Logic em movimento reciprocante (REL) e manual acorde Machado (MAN) (p<0.05). Diferenças entre as centricidades foram encontradas à 1, 4 e 5mm do canais simulados (p<0.05). À 1mm, região final do preparo, os grupos WOG e ROL realizaram preparos mais centralizados que os grupos MAN e REL. Aos 4mm, região de curvatura do canal simuado, o grupo WOG apresentou os preparos mais centralizados quando comparados à REL, ROL e MAN. Ainda na região da curvatura, aos 5mm, uma maior centricidade de preparo foi encontrado em WOG quando comparado à MAN. Considerando-se todas as alturas do canal simulado, o sistema WOG apresentou os preparos mais centralizados e o grupo ROL os menores tempos de trabalho. Observando-se os critérios qualidade de preparo e tempo de instrumentação associados, a técnica com o sistema Wave One Gold se mostrou indicada para uso por iniciantes da prática endodôntica / During endodontic preparation procedure, the goal of any operator is to perform a centering shaping with the shortest possible working time, regardless of their experience or the technique used. The challenges encountered for performing the ideal shaping may include difficulties such as root canal curvatures and the inexperience of the performer. The single file systems have shown favorable results regarding their shape ability and working time. In addition, this technique has simplicity in its \"modus-operandi\", encouraging studies that observe its application at the beginning of the endodontic practice. In order to observe single file systems behavior\'s in this niche of operators, was selected undergraduate students. In order to evaluate 12 different operators, 48 simulated root canals (Dentsply Sirona, Ballaigues, Switzerland) were used, where each operator was instrumented: 1 with a manual acorde Machado technique, 1 with Wave One Gold Primary system (Dentsply Sirona, Ballaigues), 1 with ProDesign Logic system 25.06 (Easy Equip., Belo Horizonte, Brazil) in continuous rotatory movement and 1 with ProDesign Logic system 25.06 (Easy Equip., Belo Horizonte, Brazil) in reciprocating movement (n = 48). ). After instrumentation, the shape ability produced was evaluated by cententering ratios and working time criteria. As for the quality of the preparation, through superimposed images and with the aid of the program Adobe Photoshop CC 2018 (Adobe Systems, San Jose, CA), centering values were obtained at the legths of 1 to 9mm of the simulated root canal. Working time was assesed excluding instruments exchanges and canal irrigation. For the comparative analysis of the working time between groups, the Anova 1 factor test with correction and post-test of Tukey for the multiple comparisons was used. The centering ability was analyzed by the Kruskal-Wallis test with the Dunn post-test for multiple comparisons. As a result, the Prodesign Logic group in rotatory motion (ROL) presented the shortest instrumentation time, followed by the Wave One Gold (WOG) group and, with the highest indexes, Prodesign Logic in reciprocating motion (REL) and manual acorde Machado techqnique (MAN) groups (p <0.05). Differences between centering ratios were found at 1, 4 and 5 mm of simulated root canals (p <0.05). At 1mm, apical region, WOG and ROL groups performed more centering preparations than MAN and REL groups. At 4mm, region of curvature, WOG group presented the most centering ability when compared to REL, ROL and MAN. Still on curvature portion, at 5mm, a greater centering ratio was found in WOG when compared to MAN. Considering all lengths of the simulated root canal, WOG system presented better shape ability and the ROL group the shortest working times. By observing shape ability associated with instrumentation time, was possible to conclude that Wave One Gold system is indicated for beginners of endodontic practice
169

Non-simple abelian varieties and (1,3) Theta divisors

Borowka, Pawel January 2012 (has links)
This thesis studies non-simple Jacobians and non-simple abelian varieties. The moti- vation of the study is a construction which gives a distinguished genus 4 curve in the linear system of a (1, 3)-polarised surface. The main theorem characterises such curves as hyperelliptic genus 4 curves whose Jacobian contains a (1, 3)-polarised surface. This leads to investigating the locus of non-simple principally polarised abelian g- folds. The main theorem of this part shows that the irreducible components of this locus are Is~, defined as the locus of principally polarised g-folds having an abelian subvariety with induced polarisation of type d. = (d1, ... , dk), where k ≤ g/2 Moreover, there are theorems which characterise the Jacobians of curves that are etale double covers or double covers branched in two points. There is also a detailed computation showing that, for p > 1 an odd number, the hyperelliptic locus meets IS4(l,p) transversely in the Siegel upper half space
170

Extension Operators and Finite Elements for Fractal Boundary Value Problems

Evans, Emily Jennings 20 April 2011 (has links)
The dissertation is organized into two main parts. The first part considers fractal extension operators. Although extension operators are available for general subsets of Euclidean domains or metric spaces, our extension operator is unique in that it utilizes both the iterative nature of the fractal and finite element approximations to construct the operator. The resulting operator is especially well suited for future numerical work on domains with prefractal boundaries. In the dissertation we prove the existence of a linear extension operator, Π from the space of Hölder continuous functions on a fractal set S to the space of Hölder continuous functions on a larger domain Ω. Moreover this same extension operator maps functions of finite energy on the fractal to H1 functions on the larger domain Ω. In the second part, we consider boundary value problems in domains with fractal boundaries. First we consider the Sierpinski prefractal and how we might apply the technique of singular homogenization to thin layers constructed on the prefractal. We will also discuss numerical approximation in domains with fractal boundaries and introduce a finite element mesh developed for studying problems in domains with prefractal Koch boundaries. This mesh exploits the self-similarity of the Koch curve for arbitrary rational values of α and its construction is crucial for future numerical study of problems in domains with prefractal Koch curve boundaries. We also show a technique for mesh refinement so that singularities in the domain can be handled and present sample numerical results for the transmission problem.

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