Non-Marcus energy gap dependence of electron transfer rate in contact ion pairs. Novel interplay between relaxation and reaction in solution

Electron transfer reactions between donor-acceptor pairs in solution and in organized media exhibit diverse behaviour. Recent experiments have indicated an interesting breakdown of the Marcus parabolic energy gap dependence in the normal regime for back electron transfer from contact ion pairs. A novel explanation of this breakdown has recently been proposed (M. Tachiya and S. Murata, J. Am. Chem. Sec., 116(1994) 2434) which attributes the breakdown to the interplay between the relaxation in the reactant well and the reaction. A particularly interesting aspect of the model is that it envisages the electron transfer in the normal regime to take place from a completely non-equilibrium condition. In this article a time dependent solution of the model is presented for the first time, after generalizing it to include a realistic initial population distribution. The decay of the contact ion pair population is completely non-exponential. This can be used to check the validity of the Tachiya-Murata model. The dynamics of electron transfer from the solvent separated ion pair, which seem to obey the Marcus relation, is exponential.

Quantum and non-Markovian effects in the electron transfer reaction dynamics in the Marcus inverted region

Electron transfer reactions in large molecules may often be coupled to both the polar solvent modes and the intramolecular vibrational modes of the molecule. This can give rise to a complex dynamics which may in some systems, like betaine, be controlled more by vibrational rather than by solvent effects. Additionally, a significant contribution from an ultrafast relaxation component in the solvation dynamics may enhance the complexity. To explain the wide range of behavior that has been observed experimentally, Barbara et al. recently proposed that a model of an electron transfer reaction should minimally consist of a low-frequency classical solvent mode (X), a low-frequency vibrational mode (Q), and a high-frequency quantum mode (q) (J. Phys. Chem. 1991, 96, 3728). In the present work, a theoretical study of this model is described. This study generalizes earlier work by including the biphasic solvent response and the dynamics of the low-frequency vibrational mode in the presence of a delocalized, extended reaction zone. A novel Green's function technique has been developed which allowed us to study the non-Markovian dynamics on a multidimensional surface. The contributions from the high-frequency vibrational mode and the ultrafast component in the non-Markovian solvent dynamics are found to be primarily responsible for the dramatic increase in charge transfer rate over the prediction of the classical theories that neglect both these factors. These, along with a large coupling between the reactant and the product states, may combine to render the electron transfer rate both very large and constant over a wide range of solvent relaxation rates. A study on the free energy gap dependence of the electron transfer rate reveals that the rates are sensitive to changes in the quantum frequency particularly when the free energy gap is very large.

Epistolas Varias que Consagra a la Catolica Magestad Del Rey D. Carlos Segundo, N.S. Monarca de las Espanas y del Nuevo Mundo, Don Felix de Lucio Espinosa y Malo, su autor, doctor en ambos derechos, con privilegio

Félix de Lúcio Espinosa y Maio, escritor e historiador espanhol, nasceu em Zaragoza, em 1646, e morreu em Palermo, Itália, em 1691. Doutorou-se em Direito na Universidade de Nápoles, foi Secretário do Conselho de Sua Majestade e Secretário de Estado e Guerra, no reino da Sicília. Cronista do reino de Aragão, das Índias e de Castela e Leão. Distinguiu-se por seu talento e sua cultura. ‘Epistolas varias...’ traz composições poéticas em forma de cartas, descrevendo entre outras coisas: ‘Del origem de las estatuas’, ‘De los sepulcros antigos’, ‘Del origem de las monedas’, ‘De la causa dei terremoto’, ‘Descripcion de la fiesta de toros de Madrid’, ‘De la velocidad dei tiempo’, ‘Consolatoria en la muerte’, ‘De la pintura, y alguns inventores’, ‘La paz y la union’, ‘Sobre eI origen de la poesia en varias naciones’

A campanha presidencial de 2006 e as estratégias utilizadas por eleitores para o processamento das informações políticas

Esta é uma tese centrada nas estratégias empregadas pelos eleitores para o processamento das informações sobre a política, no contexto da campanha presidencial brasileira de 2006. Propusemos, neste trabalho, um modelo estatístico para o processamento da informação sobre a política, construído a partir da contribuição de estudos realizados nos campos de conhecimento das ciências sociais, da economia, da psicologia cognitiva e da comunicação, e, sobretudo, a partir das evidências extraídas de nosso desenho de pesquisa. Este combinou métodos qualitativo, quantitativo e a análise das estratégias retóricas empregadas por candidatos e partidos políticos no Horário Gratuito de Propaganda Eleitoral (HGPE), elemento dinâmico de nosso estudo, por sintetizar os fluxos de informação no ambiente das campanhas políticas. Esse conjunto de abordagens metodológicas, foi empregado para o estudo de caso do eleitor belo-horizontino, inserido no complexo ambiente informacional das campanhas presidenciais. Com informações incompletas, o eleitor precisou escolher em quem acreditar, lidando com a incerteza dos resultados do pleito e com a incerteza em relação ao comportamento futuro dos atores, cioso de que as retóricas da campanha estavam orientadas para a persuasão. O nosso trabalho procurou mapear as estratégias empregadas pelos eleitores na seleção de temas do debate para a atenção e para o processamento das novas informações sobre a política, adquiridas em interações múltiplas ao longo da campanha. Essa complexa tarefa foi destinada à escolha de por quem ser persuadido. Procuramos responder, neste trabalho, a partir das evidências empíricas, várias preocupações deste campo de conhecimento, entre elas: 1) Em meio a tantos temas abordados na disputa entre partidos e candidatos, quais deles e por que o indivíduo escolhe para prestar atenção e acreditar? 2) Que variáveis intermedeiam e qual o seu peso nesse processo de interação com as novas informações para explicar a tomada de decisão? 3) As prioridades da agenda política do eleitor se alteram ao longo da campanha? 4) Os eleitores ampliam o repertório mais geral de informação sobre a política? 5) As percepções sobre avaliação de governo e em relação aos temas prioritários da agenda do eleitor se alteram ao longo da campanha?

Genome-wide meta-analysis identifies 11 new loci for anthropometric traits and provides insights into genetic architecture

Approaches exploiting trait distribution extremes may be used to identify loci associated with common traits, but it is unknown whether these loci are generalizable to the broader population. In a genome-wide search for loci associated with the upper versus the lower 5th percentiles of body mass index, height and waist-to-hip ratio, as well as clinical classes of obesity, including up to 263,407 individuals of European ancestry, we identified 4 new loci (IGFBP4, H6PD, RSRC1 and PPP2R2A) influencing height detected in the distribution tails and 7 new loci (HNF4G, RPTOR, GNAT2, MRPS33P4, ADCY9, HS6ST3 and ZZZ3) for clinical classes of obesity. Further, we find a large overlap in genetic structure and the distribution of variants between traits based on extremes and the general population and little etiological heterogeneity between obesity subgroups.

Defining the role of common variation in the genomic and biological architecture of adult human height

Using genome-wide data from 253,288 individuals, we identified 697 variants at genome-wide significance that together explained one-fifth of the heritability for adult height. By testing different numbers of variants in independent studies, we show that the most strongly associated 1/42,000, 1/43,700 and 1/49,500 SNPs explained 1/421%, 1/424% and 1/429% of phenotypic variance. Furthermore, all common variants together captured 60% of heritability. The 697 variants clustered in 423 loci were enriched for genes, pathways and tissue types known to be involved in growth and together implicated genes and pathways not highlighted in earlier efforts, such as signaling by fibroblast growth factors, WNT/I 2-catenin and chondroitin sulfate-related genes. We identified several genes and pathways not previously connected with human skeletal growth, including mTOR, osteoglycin and binding of hyaluronic acid. Our results indicate a genetic architecture for human height that is characterized by a very large but finite number (thousands) of causal variants.

New genetic loci link adipose and insulin biology to body fat distribution

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms.

Genetic studies of body mass index yield new insights for obesity biology

Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10(-8)), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ∼2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.