I. Configurational stability and redistribution equilibria in organomagnesium compounds. II. Redistribution equilibria in organocadmium compounds

I. CONFIGURATIONAL STABILITY AND REDISTRIBUTION EQUILIBRIA IN ORGANOMAGNESIUM COMPOUNDS

The dependence of the rate of inversion of a dialkylmagnesium compound on the solvent has been studied.

Examination of the temperature dependence of the nuclear magnetic resonance spectrum of 1-phenyl-2-propylmagnesium bromide in diethyl ether solution indicates that inversion of configuration at the methylene group of this Grignard reagent occurs with an approximate rate of 2 sec^-1 at room temperature. This is the first example of a rapid inversion rate in a secondary Grignard reagent.

The rates of exchange of alkyl groups between dineopentylmagnesium and di-s-butylmagnesium, bis-(2-methylbutyl)-magnesium and bis-(4, 4-dimethyl-2-pentyl)-magnesium respectively in diethyl ether solution were found to be fast on the nmr time scale. However, the alkyl group exchange rate was found to be slow in a diethyl ether solution of dineopentylmagnesium and bis-(2-methylbutyl)-magnesium containing N, N, N', N'-tetramethylethylenediamine. The unsymmetrical species neopentyl-2-methylbutyl-magnesium was observed at room temperature in the nmr spectrum of the solution containing the diamine.

II. REDISTRIBUTION EQUILIBRIA IN ORGANOCADMIUM COMPOUNDS

The exchange of methyl groups in dimethylcadmium has been studied by nuclear magnetic resonance spectroscopy. Activation parameters for the methyl group exchange have been measured for a neat sample and for a solution in tetrahydrofuran. The exchange is faster in the basic solvent tetrahydrofuran relative to the neat sample and in tetrahydrofuran solution is retarded by the solvating agent N, N, N’, N’-tetramethylethylenediamine and greatly increased by cadmium bromide. The addition of methanol to a solution of dimethylcadmium in tetrahydrofuran appears to have very little effect on the rate of exchange. The exchange was found to proceed with retention of configuration. The rate-limiting step for the exchange of methyl groups in a basic solvent appears to be the dissociation of coordinating solvent from dimethylcadmium.

The equilibrium between methylcadmium bromide, dimethylcadmium and cadmium bromide in tetrahydrofuran solution has also been studied. At room temperature the interconversion of the species is very fast on the nmr time scale but at -100° distinct absorptions for methylcadmium bromide and imethylcadmium are observed.

The species ethylmethylcadmium has been observed in the nmr spectrum.

The rate of exchange of vinyl groups in a solution of divinylcadmium in tetrahydrofuran has been found to be fast on the nmr time scale.

Exposição cambial: o impacto do câmbio nas ações das empresas brasileiras internacionalizadas

O aumento da internacionalização das economias emergentes e a tendência de financeirização da economia mundial motivaram este estudo que tem como principal objetivo analisar estatisticamente o impacto das variações cambiais no retorno das ações das principais empresas brasileiras internacionalizadas, segundo o ranking realizado pela Fundação Dom Cabral, no período entre 2000 e 2012. Além disso, buscou-se, também, descrever o processo inicial de internacionalização dessas mesmas companhias. Para isso, foi realizada uma pesquisa descritiva e quantitativa, por meio da utilização do método estatístico de regressão linear múltipla. Constatou-se que nas 28 empresas analisadas não há correlação entre variações nas taxas de câmbio e variações no retorno das ações das empresas brasileiras internacionalizadas, evidenciando assim, que outras variáveis são as responsáveis por impactarem o retorno dessas ações. Verificou-se, ainda, que a maior parte das empresas brasileiras iniciam seu processo de internacionalização por meio da instalação de linhas de produção no exterior, seguida de exportação e fusões e aquisições com outras companhias.

The California Red Sea Urchin, Strongylocentrotus franciscanus, Fishery: Catch, Effort, and Management Trends

California's red sea urchin, Strongylocentrotus franciscanus, catch peaked at 23,577 metric tons (t) in 1988. Since then, catches and CPUE have trended downward at different rates in northern and southern California, with 10,086 t landed statewide in 1995. West coast sea urchin catches and CPUE from British Columbia, Can., to Baja California, Mex., have generally declined during this period which followed a decade of rapid fishery expansion. This expansion was in response to increasing demand from Japan fueled by rising prices based largely on a more favorable export currency exchange rate. West coast stock assessment methods have been based on integrating a combination of fisheries dependent data and population surveys into models at various levels of complexity. California management policy has centered on technical measures such as size limits and seasonal closures and has been largely ineffective in stabilizing declining catches.

Taxa de câmbio e exportações brasileiras: uma análise do período recente

Esta dissertação tem por objetivo analisar o comportamento da balança comercial no Brasil no período de 1999 a 2006 e buscar compreender os fatores que contribuíram positivamente para a evolução das exportações, compensando os efeitos negativos advindos do movimento de apreciação da taxa de câmbio ocorrido a partir de 2003. Para tanto, a partir da adaptação de um modelo de oferta e demanda das exportações, elaborado por Goldstein e Khan (1978), utiliza-se dois métodos de estimação para a obtenção das elasticidades com relação às variáveis explicativas do modelo. O primeiro método consiste na estimação de um modelo simultâneo de oferta e demanda das exportações e o segundo método consiste no modelo de cointegração proposto por Engle e Granger. Em ambos os casos, as exportações foram desagregadas por classes de produtos (manufaturados, semimanufaturados e básicos), além do total das exportações.Do lado da demanda, os resultados estimados em ambos os métodos de estimação, tanto para o longo como para o curto prazo, confirmam as hipóteses levantadas ao longo do estudo ou seja, o crescimento dos preços dos produtos exportados, assim como o crescimento da renda mundial, foram bastante relevantes para o crescimento das exportações em todas as classes de produtos analisadas. Em relação à oferta de exportação, a taxa de utilização da capacidade produtiva e os preços dos produtos exportados estiveram co-relacionados positivamente com o quantum ofertado, enquanto que a taxa de câmbio, ao contrário do esperado, apresentou elasticidades negativas.

A Zona do Euro e a Teoria de Áreas Monetárias Ótimas: uma análise utilizando um Vetor Autorregressivo Aumentado por Fatores Dinâmicos (FAVAR)

Este trabalho tem como objetivos analisar as semelhanças das respostas dos países da Zona do Euro aos choques na política monetária e no câmbio (identificados através de restrições de sinais nas funções impulso-resposta) e investigar a simetria das flutuações na taxa de crescimento do nível de atividade na região através da análise da importância relativa da resposta do crescimento do PIB destes países aos choques comum e específico identificados pelo modelo FAVAR utilizado, que foi estimado através de um método Bayesiano desenvolvido para incorporar prioris de Litterman (1986). A importância do choque comum (relativamente ao específico) nos diversos países, fornece uma medida do grau de integração dos diversos membros da Zona do Euro. O trabalho contribui para a análise do grau de integração dos países da Zona do Euro ao utilizar uma metodologia que permite o uso de um amplo conjunto de variáveis e ao identificar o grau de simetria das flutuações na taxa de crescimento do nível de atividade dos membros da região através da identificação dos choques comuns e específicos. Foram utilizados dados trimestrais de 1999.I a 2013.I para os 17 países da região. Os resultados encontrados apontam para a existência de uma maior integração entre as grandes economias da Zona do Euro ( com exceção da França) e uma integração menor para as menores economias (com exceção da Finlândia).

A habilidade preditiva e os impactos dos choques na política monetária e no câmbio: comparações entre modelos DSGE, VAR e BVAR estimados para o Brasil

Este artigo compara a habilidade preditiva foradaamostra de um modelo DSGE (DynamicStochastic General EquilibriumModel)Novo-Keynesiano, especificado e estimado para o Brasil, com a de um modelo Autorregressivo Vetorial (VAR) e com a de um modelo AutorregressivoVetorial Bayesiano (BVAR). O artigo inova em relação a outros trabalhos similares feitos para o Brasil (Castro et al. (2011) e Caetano e Moura (2013)), ao escolher uma especificação para o modelo DSGE que, ao permitir o uso de um conjunto de informação mais rico, tornou possível computar-se a habilidade preditiva do DSGE a partir de previsões que são,verdadeiramente,previsõesfora da amostra. Ademais, diferentemente de outros artigos que utilizaram dados brasileiros, avalia-se em que medida as respostas das variáveis aos choques na política monetária e no câmbio, obtidas pelo modelo DSGE, se assemelham àquelas de um BVAR estimado através de procedimentos bayesianos desenvolvidos de forma consistente. O modelo DSGE estimado é similar ao utilizado por Justiniano e Preston (2010) e Alpanda (2010). O modelo BVAR foi estimado utilizando uma metodologia semelhante à desenvolvida por Sims e Zha (1998), Waggoner e Zha (2003) e Ramírez, Waggoner e Zha (2007).Os resultados obtidos mostram que o modelo DSGE é capaz de gerar, para algumas variáveis, previsões competitivas em relação às dos outros modelos rivais VAR e BVAR. Além disso, as respostas das variáveis aos choques nas políticas monetária e cambial, nos modelos DSGE e BVAR, são bastante similares.

黄土高原林草水土保持有效盖度分析

根据黄土高原绥德、延安、安塞和离石等地林、草地径流小区降雨侵蚀资料，对不同降雨和坡度下林、草地水土保持有效盖度进行了分析，建立了林地、草地水土保持临界有效益度与降雨及坡度的关系式。在土壤和植被类型相对稳定的条件下，林、草地的有效益度随着降雨和坡度的增大而增大，当临界有效益度达到一定程度时，降雨和坡度的影响减弱；在其它条件相同时，同一水土保持作用所要求的有效盖度草地比林地大。并结合降雨频率分析，得出了林、草措施抵抗不同年遇暴雨时的临界有效盖度。

人工草地在黄土高原水土保持中的减水减沙效益与有效盖度

根据黄土高原绥德、延安 、离石、安塞等地的草地径流小区资料，分析不同次降雨条件下，人工草地的减水减沙效益和水土保持有效盖度。结果表明，当降雨指标小于坡耕地侵蚀性降雨标准时，草地并不发挥水土保持作用，减水减沙效益为零，当降雨指标大于坡耕地侵蚀性标准时，其减水减沙效益随着降雨指标的增大而减小。在土壤相对稳定的情况下，要使土壤侵蚀模数小于某一定值， 降雨、地形和植被覆盖因子三者之间存在着一定的相互制约关系，即草地的盖度随着降雨和坡度的增大而增大，当盖度达到一定程度时，降雨与坡度对其的制约影响减弱。建立草地的减水减沙效益指标体系，及草地水土保持临界有效盖度与降雨坡度的关系式，并结合降雨频率的分析，得出草地抵抗不同年暴雨的临界有效盖度。

Effects of diet, stocking density, and environmental factors on growth, survival, and metamorphosis of Manila clam Ruditapes philippinarum larvae

A series of experiments was conducted to evaluate the effects of diet, stocking density, and environmental factors on growth, survival, and metamorphosis of Manila clam Ruditapes philippinarum larvae. These experiments examined the following factors: diet (Isochrysts spp., Chlorella spp., and a mixture of Isochrysis spp. and Chlorella spp. [ 1: 1 w/w]), stocking density (5, 10, 15, and 20 larvae ml(-1)), light intensity (un-shaded, partially shaded, and fully shaded), water filtration (unfiltered and sand-filtered), water exchange (50% and 100% once every other day, 25%, 50%, and 100% once daily; 50% and 100% twice daily), and the use of substrate (with and without sand as the substrate). Results indicated that Chlorella spp. could replace 50% of Isochrysis spp. as a food source for the Manila clam larvae without affecting growth, survival, and metamorphosis. Larval growth decreased significantly with increasing stocking density. A density of 5-10 larvae ml(-1) appeared to be optimal for normal growth of Manila clam larvae. Neither diet nor stocking density used in the study had a significant effect on larval survival. Under partially shaded (light intensity = 1000-5000 lx) and fully shaded (light intensity <500 lx) conditions, larval growth was significantly faster than under direct sunlight (un-shaded). A water exchange rate of 50% twice daily provided optimum larval growth. Larvae grew significantly faster in the unfiltered water than in the sand-filtered water. Using sand as the substrate in the culture system significantly depressed the metamorphosis rate. The type and particle size of sand used as the substrate did not significantly affect growth and metamorphosis rates of the larvae. (C) 2005 Published by Elsevier B.V.

The financial storms in Vietnam's transition economy: a reasoning on the 1991-2008 period

This study focuses on those substantial changes that characterize the shift of Vietnam’s macroeconomic structures and evolution of micro-structural interaction over an important period of 1991-2008. The results show that these events are completely distinct in terms of (i) Economic nature; (ii) Scale and depth of changes; (iii) Start and end results; and, (iv) Requirement for macroeconomic decisions. The study rejected a suspicion of similarity between the contagion of the Asian financial crisis in 1997-98 and economic chaos in the first half of 2008 (starting from late 2007). The depth, economic settings of, and interconnection between macro choices and micro decisions have all grown up significantly, partly due to a much deeper level of integration of Vietnam into the world’s economy. On the one hand, this phenomenon gives rise to efficiency of macro level policies because the consideration of micro-structural factors within the framework has definitely become increasingly critical. On the other and, this is a unique opportunity for the macroeconomic mechanism of Vietnam to improve vastly, given the context in which the national economy entered an everchanging period under pressures of globalization and re-integration. The authors hope to also open up paths for further empirical verifications and to stress on the fact that macro policies will have, from now on, to be decided in line with changing micro-settings, which specify a market economy and decide the degree of success of any macroeconomic choices.

A Note on Studies of Monetary Policy and Implementation in Vietnam

In this short paper, we have gone through some key results of monetary policy research applied for the Vietnamese economy, over the past 20 years after Doi Moi, together with a few caveats when putting these results in use. We look at different research themes, and suggest that future research make better and more diverse choice of analytic framework, and also put macro and micro-setting connection at work, which appear to likely bring about better and more insightful results for the monetary economics literature in Vietnam.

Energy recovery in individuals with knee osteoarthritis.

OBJECTIVE: Pathological gaits have been shown to limit transfer between potential (PE) and kinetic (KE) energy during walking, which can increase locomotor costs. The purpose of this study was to examine whether energy exchange would be limited in people with knee osteoarthritis (OA). METHODS: Ground reaction forces during walking were collected from 93 subjects with symptomatic knee OA (self-selected and fast speeds) and 13 healthy controls (self-selected speed) and used to calculate their center of mass (COM) movements, PE and KE relationships, and energy recovery during a stride. Correlations and linear regressions examined the impact of energy fluctuation phase and amplitude, walking velocity, body mass, self-reported pain, and radiographic severity on recovery. Paired t-tests were run to compare energy recovery between cohorts. RESULTS: Symptomatic knee OA subjects displayed lower energetic recovery during self-selected walking speeds than healthy controls (P = 0.0018). PE and KE phase relationships explained the majority (66%) of variance in recovery. Recovery had a complex relationship with velocity and its change across speeds was significantly influenced by the self-selected walking speed of each subject. Neither radiographic OA scores nor subject self-reported measures demonstrated any relationship with energy recovery. CONCLUSIONS: Knee OA reduces effective exchange of PE and KE, potentially increasing the muscular work required to control movements of the COM. Gait retraining may return subjects to more normal patterns of energy exchange and allow them to reduce fatigue.

Fixed versus Flexible: lessons from EMS order Flow

We extend the literature on regime-dependent volatility in two ways. First, our microstructural model provides a qualitatively new explanation. Second, we test implications of our model using Europe's recent shift to rigidly fixed rates (EMS to EMU). In the model, shocks to order flow induce more volatility under flexible rates because the elasticity of speculative demand is (endogenously) low, leading to pronounced portfolio-balance effects. New data on FF/DM transactions show that order flow had persistent effects on the exchange rate before EMU parities were announced. After announcement, the FF/DM rate was decoupled from order flow, as the model predicts.

Quantitative analysis of the reactivity of formate species seen by DRIFTS over a Au/Ce(La)O2 water–gas shift catalyst: First unambiguous evidence of the minority role of formates as reaction intermediates

The reactivity of the species formed at the surface of a Au/Ce(La)O2 catalyst during the water������¢���¯���¿���½���¯���¿���½gas shift (WGS) reaction were investigated by operando diffuse reflectance Fourier transform spectroscopy (DRIFTS) at the chemical steady state during isotopic transient kinetic analyses (SSITKA). The exchanges of the reaction product CO2 and of formate and carbonate surface species were followed during an isotopic exchange of the reactant CO using a DRIFTS cell as a single reactor. The DRIFTS cell was a modified commercial cell that yielded identical reaction rates to that measured over a quartz plug-flow reactor. The DRIFTS signal was used to quantify the relative oncentrations of the surface species and CO2. The analysis of the formate exchange curves between 428 and 493 K showed that at least two levels of reactivity were present. ������¢���¯���¿���½���¯���¿���½Slow formates������¢���¯���¿���½���¯���¿���½ displayed an exchange rate constant 10- to 20-fold slower than that of the reaction product CO2. ������¢���¯���¿���½���¯���¿���½Fast formates������¢���¯���¿���½���¯���¿���½ were exchanged on a time scale similar to that of CO2. Multiple nonreactive readsorption of CO2 took place, accounting for the kinetics of the exchange of CO2(g) and making it impossible to determine the number of active sites through the SSITKA technique. The concentration (in mol g������¢���¯���¿���½���¯���¿���½1) of formates on the catalyst was determined through a calibration curve and allowed calculation of the specific rate of formate decomposition. The rate of CO2 formation was more than an order of magnitude higher than the rate of decomposition of formates (slow + fast species), indicating that all of the formates detected by DRIFTS could not be the main reaction intermediates in the production of CO2. This work stresses the importance of full quantitative analyses (measuring both rate constants and adsorbate concentrations) when investigating the role of adsorbates as potential reaction intermediates, and illustrates how even reactive species seen by DRIFTS may be unimportant in the overall reaction scheme.