Optimization in a Simulation Setting: Use of Function Approximation in Debt Strategy Analysis

The stochastic simulation model suggested by Bolder (2003) for the analysis of the federal government's debt-management strategy provides a wide variety of useful information. It does not, however, assist in determining an optimal debt-management strategy for the government in its current form. Including optimization in the debt-strategy model would be useful, since it could substantially broaden the range of policy questions that can be addressed. Finding such an optimal strategy is nonetheless complicated by two challenges. First, performing optimization with traditional techniques in a simulation setting is computationally intractable. Second, it is necessary to define precisely what one means by an "optimal" debt strategy. The authors detail a possible approach for addressing these two challenges. They address the first challenge by approximating the numerically computed objective function using a function-approximation technique. They consider the use of ordinary least squares, kernel regression, multivariate adaptive regression splines, and projection-pursuit regressions as approximation algorithms. The second challenge is addressed by proposing a wide range of possible government objective functions and examining them in the context of an illustrative example. The authors' view is that the approach permits debt and fiscal managers to address a number of policy questions that could not be fully addressed with the current stochastic simulation engine.Debt management; Econometric and statistical methods; Fiscal policy; Financial markets

Optimization in a Simulation Setting: Use of Function Approximation in Debt Strategy Analysis

This paper provides an analysis of how a firm's decision to serve a foreign market by exporting or by engaging in foreign direct investment (FDI) affects firm productivity, when productivity is endogeneous as a function of training. The main result of our paper is that, with endogeneous productivity, exporting results in lower productivity than does FDI, but exporting may result in higher or lower employment and output than does FDI. We also show that FDI has lower employment, higher training, higher wages and higher productivity than does production for the home market. A further interesting and unexpected result of our model is that exporting results in the same level of training and productivity as does production for the home market. However, under the same demand conditions, the exporting firm employs less labour for foreign production than for home production and, consequently, output for the foreign market is lower than output for the home market. In addition, we investigate the firm's decision to serve the foreign market by exporting or by engaging in FDI and determine parameter values for which either regime is chosen.International topics; Labour markets; Productivity

Assessing the Impact of Unilingualism at the Supreme Court of Canada: Panel Composition, Assertiveness, Caseload, and Deference

This paper is a first empirical foray in the debate concerning mandatory bilingualism for Supreme Court judges in Canada. The paper summarizes the main arguments, discusses the framing of bilingualism as a “legal” or an “identity” requirement, and uses empirical data to assess whether unilingualism has had an impact on four dimensions of the decision-making process at the Supreme Court of Canada: panel composition, assertiveness, individual caseloads and deference towards lower courts by unilingual and bilingual judges. Our results suggest that there is a correlation between the fluency in French and the first three elements but that there is no difference in the level of deference across linguistic groups towards francophone lower courts. Even if the paper is exploratory in nature and warrants further research, the general picture that emerges is that language proficiency superimposes itself as another kind of legal specialization in the inner-working of the Court

Spatiotemporal correlations of aftershock sequences

Aftershock sequences are of particular interest in seismic research since they may condition seismic activity in a given region over long time spans. While they are typically identified with periods of enhanced seismic activity after a large earthquake as characterized by the Omori law, our knowledge of the spatiotemporal correlations between events in an aftershock sequence is limited. Here, we study the spatiotemporal correlations of two aftershock sequences form California (Parkfield and Hector Mine) using the recently introduced concept of "recurrent" events. We find that both sequences have very similar properties and that most of them are captured by the space-time epidemic-type aftershock sequence (ETAS) model if one takes into account catalog incompleteness. However, the stochastic model does not capture the spatiotemporal correlations leading to the observed structure of seismicity on small spatial scales.Comment: 31 pages, 5 figure

A GOVERNANÇA DA CADEIA PRODUTIVA DO LEITE: UM ESTUDO DE CASO NA REGIÃO DO COREDE RIO DA VÁRZEA – RS

A estrutura de governança é um dos fatores determinantes para o sucesso de uma cadeia produtiva com a capacidade de integrar, coordenar e articular ações conjuntas em prol do seu desenvolvimento. Nesse sentido, o objetivo do estudo foi caracterizar e analisar a governança e a cadeia produtiva do leite na região do Conselho Regional de Desenvolvimento Rio da Várzea. Dessa forma, foi realizada uma pesquisa descritiva, qualitativa, utilizando como instrumentos a pesquisa documental, observação direta e entrevista semiestruturada com 9 (nove) agentes da cadeia produtiva do leite da região. Em seguida, após as transcrições, procedeu-se à análise de conteúdo, identificando-se três categorias: coordenação, oportunidades e desafios. Pode-se verificar que há muitas entidades trabalhando em prol da cadeia produtiva, em que pese de forma isolada e com raros momentos de interação, constatando a existência de uma governança informal e híbrida carente de mecanismos de gestão. Sendo assim, com o envolvimento entre os agentes, em um processo coletivo, integrado, de aprendizado, crescimento e qualificação, é possível maximizar os recursos, ter uma cadeia mais consolidada e organizada, contribuindo para o seu fortalecimento, tendo uma opção de potencialização para a cadeia produtiva e a região a formalização e constituição de um Arranjo Produtivo Local (APL). Por fim, destaca-se que a cooperação entre os agentes deve ser incentivada, com foco principal nos desafios, o que proporcionará aos produtores, empresas e os municípios, desenvolvimento econômico, social e ambiental

Genome of the Avirulent Human-Infective Trypanosome—Trypanosoma rangeli

Background: Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.  Methodology/Principal Findings: The T. rangeli haploid genome is ,24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heatshock proteins.  Conclusions/Significance: Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets

Hospedabilidade de genótipos de soja a Meloidogyne arenaria e Meloidogyne morocciensis

Soybean crop productivity is limited by several biotic factors, particularly plant-parasitic nematodes. Several species have been reported to cause crop damage, especially those of the genus Meloidogyne. Therefore, the aim of this study was to evaluate, the reaction of 28 soybean genotypes to Meloidogyne arenaria and M. morocciensis in a greenhouse. The soybean genotypes were the same for experiments with different species of plant-parasitic nematodes and were individually inoculated with 5,000 eggs + second-stage juveniles (J2) of Meloidogyne and kept in a greenhouse. After 60 days of inoculation, the roots of each plant were assessed for the number of galls, final population, and reproduction factor (RF = final population/initial population). The averages of the different variables were then compared to each other by the Scott-Knott cluster analysis at a significance level of 5%. All of the soybean genotypes in the study were susceptible to both nematodes, with RF ranging from 3.5 to 24.1 for M. arenaria and 5.3 to 37.5 for M. morocciensis.A cultura da soja tem sua produtividade limitada por diversos fatores bióticos, dentre estes destacam-se os fitonematoides. Várias espécies já foram relatadas causando danos à cultura, especialmente as do gênero Meloidogyne.  Diante disso, o objetivo do trabalho foi avaliar, em casa de vegetação, a reação de 28 cultivares de soja a M. arenaria e M. morocciensis. As cultivares de soja testadas foram as mesmas para os dois ensaios, sendo individualmente inoculadas com 5.000 ovos + juvenis do segundo estádio (J2) de Meloidogyne mantidas em casa de vegetação. Decorridos 60 dias da inoculação, as raízes de cada planta foram avaliadas quanto ao número de galhas, população final e fator de reprodução (FR = população final/população inicial). A seguir, as médias das diferentes variáveis foram comparadas entre si pelo teste de agrupamento de Scott e Knott a 5%. Todas as cultivares de soja avaliadas comportaram-se como suscetíveis a ambos nematoides, com FR variando 3,5 a 24,1 para M. arenaria, e de 5,3 a 37,5 para o M. morocciensis

Redox alterations in pregnant women: Antioxidant effect of lemongrass (Cymbopogon citratus (DC.) Stapf) Alterações redox em gestantes: Efeito antioxidante do capim-limão (Cymbopogon citratus (DC.) Stapf)

Purpose: This study aimed to verify the redox profile of different gestational phases of pregnant women, in addition to the antioxidant potential of the Cymbopogon citratus leaves infusion. Methods: The infusion characterization was performed by measuring total phenolics, flavonoids and condensed tannins levels. The oxidative damage markers to lipids and proteins in plasma and erythrocytes were evaluated by measuring the TBARS and carbonylated proteins (CP) levels and antioxidant activity by GSH levels. The antioxidant effects of the infusion (20 g/L) were evaluated by measuring the same markers after the pregnant women erythrocytes incubation with the same infusion. The phytochemicals with the highest concentration founded in infusion were flavonoids, followed by tannins and phenolics. Results: It was observed an increase in TBARS levels in the 2nd gestational phase in plasma, concomitant with a decrease in GSH levels in the 2nd and 3rd phases, and CP in the 1st and 4th gestational phases in relation to control. It was observed a decrease in all markers levels in erythrocytes in the 1st and 2nd phases. Analyzing the antioxidant potential of the infusion on erythrocytes, it was observed a decrease in TBARS concomitant with an increase in GSH levels, being little effective in reversing protein damage. Conclusion: Thus, it is suggested that the infusion could be used as adjuvant to vitamin supplements recommended during pregnancy