255 resultados para RECENT COMMON ANCESTRY


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Recent theory of physiology of language suggests a dual stream dorsal/ventral organization of speech perception. Using intra-cerebral Event-related potentials (ERPs) during pre-surgical assessment of twelve drug-resistant epileptic patients, we aimed to single out electrophysiological patterns during both lexical-semantic and phonological monitoring tasks involving ventral and dorsal regions respectively. Phonological information processing predominantly occurred in the left supra-marginal gyrus (dorsal stream) and lexico-semantic information occurred in anterior/middle temporal and fusiform gyri (ventral stream). Similar latencies were identified in response to phonological and lexico-semantic tasks, suggesting parallel processing. Typical ERP components were strongly left lateralized since no evoked responses were recorded in homologous right structures. Finally, ERP patterns suggested the inferior frontal gyrus as the likely final common pathway of both dorsal and ventral streams. These results brought out detailed evidence of the spatial-temporal information processing in the dual pathways involved in speech perception.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Gout is the most common inflammatory arthritis and one in which pathogenesis and risk factors are best understood. One of the treatment objectives in current guidelines is 'cure'. However, audits show that only a minority of patients with gout receive adequate advice and treatment. Suboptimal care and outcomes reflect inappropriately negative perceptions of the disease, both in patients and providers. Historically, gout has been portrayed as a benign and even comical condition that is self-inflicted through overeating and alcohol excess. Doctors often focus on managing acute attacks rather than viewing gout as a chronic progressive crystal deposition disease. Urate-lowering treatment is underprescribed and often underdosed. Appropriate education of patients and doctors, catalysed by recent introduction of new urate-lowering treatments after many years with no drug development in the field, may help to overcome these barriers and improve management of this easily diagnosed and curable form of potentially severe arthritis.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Glucocorticoids affect physiology and behaviour, reproduction and potentially sexual selection as well. Shortterm and moderate glucocorticoid elevations are suggested to be adaptive, and prolonged and high elevations may be extremely harmful. This suggests that optimal reproductive strategies, and thus sexual selection, may be dose dependent. Here, we investigate effects of moderate and high elevations of blood corticosterone levels on intra- and intersexual behaviour and mating success of male common lizards Lacerta vivipara. Females showed less interest and more aggressive behaviour towards high corticosterone males and blood corticosterone levels affected male reproductive strategy. Males of moderate and high corticosterone elevations, compared with Control males, showed increased interest (i.e., higher number of chases, tongue extrusions, and approaches) towards females and high corticosterone males initiated more copulation attempts. However, neither increased male interest nor increased copulation attempts resulted in more copulations. This provides evidence for a best-of-a-bad-job strategy, where males with higher corticosterone levels compensated for reduced female interest and increased aggressive female behaviour directed towards them, by showing higher interest and by conducting more copulation attempts. Blood corticosterone levels affected intrasexual selection as well since moderate corticosterone levels positively affected male dominance, but dominance did not affect mating success. These findings underline the importance of female mate choice and are in line with adaptive compensatory behaviours of males. They further show that glucocorticoid effects on behaviour are dose dependent and that they have important implications for sexual selection and social interactions, and might potentially affect Darwinian fitness.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Calcium has a pivotal role in biological functions, and serum calcium levels have been associated with numerous disorders of bone and mineral metabolism, as well as with cardiovascular mortality. Here we report results from a genome-wide association study of serum calcium, integrating data from four independent cohorts including a total of 12,865 individuals of European and Indian Asian descent. Our meta-analysis shows that serum calcium is associated with SNPs in or near the calcium-sensing receptor (CASR) gene on 3q13. The top hit with a p-value of 6.3 x 10(-37) is rs1801725, a missense variant, explaining 1.26% of the variance in serum calcium. This SNP had the strongest association in individuals of European descent, while for individuals of Indian Asian descent the top hit was rs17251221 (p = 1.1 x 10(-21)), a SNP in strong linkage disequilibrium with rs1801725. The strongest locus in CASR was shown to replicate in an independent Icelandic cohort of 4,126 individuals (p = 1.02 x 10(-4)). This genome-wide meta-analysis shows that common CASR variants modulate serum calcium levels in the adult general population, which confirms previous results in some candidate gene studies of the CASR locus. This study highlights the key role of CASR in calcium regulation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Afrotheria, one of four mammalian superorders, comprises elephants, sea cows, hyraxes, aardvark, elephant shrews, tenrecs and golden moles. Their placentas either form an equatorial band or are discoid in shape. The interhemal region, separating fetal and maternal blood, is endotheliochorial in elephants, aardvark and possibly the sea cows, but hemochorial in the remaining orders. There is a secondary epitheliochorial placenta in elephant shrews while a similar structure in tenrecs erodes maternal tissues. Specialized hemophagous regions are a striking characteristic of some of these placentas yet absent in hyraxes, elephant shrews, and golden moles. It is possible that the common ancestor of the Afrotheria had an endotheliochorial placenta. Establishment of a hemochorial condition, as seen in rock hyraxes, elephant shrews, tenrecs, and golden moles, would be a more recent development. The elephant, manatee, and aardvark all have circumferential placentas. Thus the formation of a discoid placenta with a more or less extensive secondary placenta in elephant shrews and tenrecs would also be a derived state.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Knowledge of the quantitative genetics of resistance to parasitism is key to appraise host evolutionary responses to parasite selection. Here, we studied effects of common origin (i.e. genetic and pre-hatching parental effects) and common rearing environment (i.e. post-hatching parental effects and other environment effects) on variance in ectoparasite load in nestling Alpine swifts (Apus melba). This colonial bird is intensely parasitized by blood sucking louse-flies that impair nestling development and survival. By cross-fostering half of the hatchlings between pairs of nests, we show strong significant effect of common rearing environment on variance (90.7% in 2002 and 90.9% in 2003) in the number of louse-flies per nestling and no significant effect of common origin on variance in the number of louse-flies per nestling. In contrast, significant effects of common origin were found for all the nestling morphological traits (i.e. body mass, wing length, tail length, fork length and sternum length) under investigation. Hence, our study suggests that genetic and pre-hatching parental effects play little role in the distribution of parasites among nestling Alpine swifts, and thus that nestlings have only limited scope for evolutionary responses against parasites. Our results highlight the need to take into consideration environmental factors, including the evolution of post-hatching parental effects such as nest sanitation, in our understanding of host-parasite relationships.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

General Summary Although the chapters of this thesis address a variety of issues, the principal aim is common: test economic ideas in an international economic context. The intention has been to supply empirical findings using the largest suitable data sets and making use of the most appropriate empirical techniques. This thesis can roughly be divided into two parts: the first one, corresponding to the first two chapters, investigates the link between trade and the environment, the second one, the last three chapters, is related to economic geography issues. Environmental problems are omnipresent in the daily press nowadays and one of the arguments put forward is that globalisation causes severe environmental problems through the reallocation of investments and production to countries with less stringent environmental regulations. A measure of the amplitude of this undesirable effect is provided in the first part. The third and the fourth chapters explore the productivity effects of agglomeration. The computed spillover effects between different sectors indicate how cluster-formation might be productivity enhancing. The last chapter is not about how to better understand the world but how to measure it and it was just a great pleasure to work on it. "The Economist" writes every week about the impressive population and economic growth observed in China and India, and everybody agrees that the world's center of gravity has shifted. But by how much and how fast did it shift? An answer is given in the last part, which proposes a global measure for the location of world production and allows to visualize our results in Google Earth. A short summary of each of the five chapters is provided below. The first chapter, entitled "Unraveling the World-Wide Pollution-Haven Effect" investigates the relative strength of the pollution haven effect (PH, comparative advantage in dirty products due to differences in environmental regulation) and the factor endowment effect (FE, comparative advantage in dirty, capital intensive products due to differences in endowments). We compute the pollution content of imports using the IPPS coefficients (for three pollutants, namely biological oxygen demand, sulphur dioxide and toxic pollution intensity for all manufacturing sectors) provided by the World Bank and use a gravity-type framework to isolate the two above mentioned effects. Our study covers 48 countries that can be classified into 29 Southern and 19 Northern countries and uses the lead content of gasoline as proxy for environmental stringency. For North-South trade we find significant PH and FE effects going in the expected, opposite directions and being of similar magnitude. However, when looking at world trade, the effects become very small because of the high North-North trade share, where we have no a priori expectations about the signs of these effects. Therefore popular fears about the trade effects of differences in environmental regulations might by exaggerated. The second chapter is entitled "Is trade bad for the Environment? Decomposing worldwide SO2 emissions, 1990-2000". First we construct a novel and large database containing reasonable estimates of SO2 emission intensities per unit labor that vary across countries, periods and manufacturing sectors. Then we use these original data (covering 31 developed and 31 developing countries) to decompose the worldwide SO2 emissions into the three well known dynamic effects (scale, technique and composition effect). We find that the positive scale (+9,5%) and the negative technique (-12.5%) effect are the main driving forces of emission changes. Composition effects between countries and sectors are smaller, both negative and of similar magnitude (-3.5% each). Given that trade matters via the composition effects this means that trade reduces total emissions. We next construct, in a first experiment, a hypothetical world where no trade happens, i.e. each country produces its imports at home and does no longer produce its exports. The difference between the actual and this no-trade world allows us (under the omission of price effects) to compute a static first-order trade effect. The latter now increases total world emissions because it allows, on average, dirty countries to specialize in dirty products. However, this effect is smaller (3.5%) in 2000 than in 1990 (10%), in line with the negative dynamic composition effect identified in the previous exercise. We then propose a second experiment, comparing effective emissions with the maximum or minimum possible level of SO2 emissions. These hypothetical levels of emissions are obtained by reallocating labour accordingly across sectors within each country (under the country-employment and the world industry-production constraints). Using linear programming techniques, we show that emissions are reduced by 90% with respect to the worst case, but that they could still be reduced further by another 80% if emissions were to be minimized. The findings from this chapter go together with those from chapter one in the sense that trade-induced composition effect do not seem to be the main source of pollution, at least in the recent past. Going now to the economic geography part of this thesis, the third chapter, entitled "A Dynamic Model with Sectoral Agglomeration Effects" consists of a short note that derives the theoretical model estimated in the fourth chapter. The derivation is directly based on the multi-regional framework by Ciccone (2002) but extends it in order to include sectoral disaggregation and a temporal dimension. This allows us formally to write present productivity as a function of past productivity and other contemporaneous and past control variables. The fourth chapter entitled "Sectoral Agglomeration Effects in a Panel of European Regions" takes the final equation derived in chapter three to the data. We investigate the empirical link between density and labour productivity based on regional data (245 NUTS-2 regions over the period 1980-2003). Using dynamic panel techniques allows us to control for the possible endogeneity of density and for region specific effects. We find a positive long run elasticity of density with respect to labour productivity of about 13%. When using data at the sectoral level it seems that positive cross-sector and negative own-sector externalities are present in manufacturing while financial services display strong positive own-sector effects. The fifth and last chapter entitled "Is the World's Economic Center of Gravity Already in Asia?" computes the world economic, demographic and geographic center of gravity for 1975-2004 and compares them. Based on data for the largest cities in the world and using the physical concept of center of mass, we find that the world's economic center of gravity is still located in Europe, even though there is a clear shift towards Asia. To sum up, this thesis makes three main contributions. First, it provides new estimates of orders of magnitudes for the role of trade in the globalisation and environment debate. Second, it computes reliable and disaggregated elasticities for the effect of density on labour productivity in European regions. Third, it allows us, in a geometrically rigorous way, to track the path of the world's economic center of gravity.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The list of chromosome races of the common shrew (Sorex araneus) was compiled, the vast literature has been scrutinized, and unpublished data have been added. Altogether, 50 chromosome races could be listed. The name and its synonyms, chromosomal constitution, author of the description, type locality, known distribution range, and additional information are reported for individual races. The present list should be considered a working document that will be regularly updated and supplemented.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

BACKGROUND: Loss of balance confidence is a frequent condition that affects 20-75% of community-dwelling older persons. Although a recent fall is a common trigger, loss of balance confidence also appears independent of previous experience with falls. Maintaining or improving balance confidence is important to avoid unnecessary, self-imposed restrictions of activity and subsequent disability. Holding another person's hand or using an assistive device while walking are simple interventions that are used naturally to address poor balance confidence in daily life. However, more complex interventions have also been developed and tested to achieve more sustained improvement in balance confidence. OBJECTIVES: This review describes interventions that have been tested to improve balance confidence in older community-dwelling persons. METHODS: Based on 2 recent systematic reviews, an additional search for literature was performed to update current information on interventions aiming at balance confidence improvement. Interventions were classified as those directly aimed at increasing balance confidence or not, and further stratified into those using monofactorial or multifactorial approaches. RESULTS: A total of 46 randomized controlled trials were identified. Five of the 8 interventions that directly targeted balance confidence showed benefits. Among those, multicomponent behavioral group interventions provided the most robust evidence of benefits in improving balance confidence and in decreasing activity avoidance. Among interventions not directly aiming at balance confidence improvement (11/21 studies with benefits), exercise (including tai chi) appears as the most promising monofactorial intervention. Nine of the 17 multifactorial fall prevention programs showed an effect on balance confidence, exercise being a main component in 7 of these 9 studies. Interventions that targeted elderly persons reporting poor balance confidence and/or those at risk for falls seemed more likely to be beneficial. CONCLUSIONS: Positive and sometimes sustained improvement in balance confidence can be achieved by various interventions among community-dwelling elderly persons. The effect of these interventions on activity restriction associated with poor balance confidence have been less well studied, but some studies also suggest potential benefits.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Peripheral NK/T-cell lymphoma (PTCL) is a heterogeneous group of uncommon hematologic malignancies with aggressive clinical course and unfavorable prognosis. Extranodal NK/T-cell lymphoma, nasal type (NKTCL) is the most common extranodal entity worldwide, with heterogeneous geographic distribution, and it is characterized by its association with EBV, a nasal or less often extranasal presentation and aggressive behavior. Recent works using array-based technologies have provided novel insights into the pathogenesis and discovered new biomarkers with diagnostic and therapeutic implications in NKTCL. Gene expression profiling identified that most of the NKTCL are derived from activated natural killer cells with distinctively high expression of granzyme H compared to other PTCLs, which might serve as a new diagnostic biomarker. Frequent deletions and promoter methylations in PRDM1, ATG5, AIM1, FOXO3, HACE1 mapping to 6q21-q25, suggest their roles as potential tumor suppressors. The deregulation of oncogenic pathways (PDGF, JAK-STAT, AKT) provides a rationale for developing targeted therapies in the future.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In recent years it has become evident that screening for and treatment of acute toxoplasmosis during pregnancy may have no measurable impact on vertical transmission and neonatal morbidity and mortality. A broad lack of evidence with regard to many aspects of congenital toxoplasmosis has been recognised in a common European initiative (EUROTOXO) which reviewed several thousand published papers on the subject of toxoplasmosis during pregnancy and childhood. It was therefore clear that the strategies currently implemented in our country would, on closer inspection, no longer withstand the claim for evidence-based procedures. The arguments and call for a change of paradigm in Switzerland which follow here are the result of a national consensus-finding process involving experts from various specialities, including gynaecology/obstetrics, paediatrics/neonatology, infectiology, ophthalmology and laboratory medicine, together with representatives of the public health authorities.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Plasma concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides are among the most important risk factors for coronary artery disease (CAD) and are targets for therapeutic intervention. We screened the genome for common variants associated with plasma lipids in >100,000 individuals of European ancestry. Here we report 95 significantly associated loci (P < 5 x 10(-8)), with 59 showing genome-wide significant association with lipid traits for the first time. The newly reported associations include single nucleotide polymorphisms (SNPs) near known lipid regulators (for example, CYP7A1, NPC1L1 and SCARB1) as well as in scores of loci not previously implicated in lipoprotein metabolism. The 95 loci contribute not only to normal variation in lipid traits but also to extreme lipid phenotypes and have an impact on lipid traits in three non-European populations (East Asians, South Asians and African Americans). Our results identify several novel loci associated with plasma lipids that are also associated with CAD. Finally, we validated three of the novel genes-GALNT2, PPP1R3B and TTC39B-with experiments in mouse models. Taken together, our findings provide the foundation to develop a broader biological understanding of lipoprotein metabolism and to identify new therapeutic opportunities for the prevention of CAD.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

(1) The common shrew Sorex araneus and Millet's shrew S. coronatus are sibling species.They are morphologically and genetically very similar but do not hybridize. Their parapatric distribution throughout south-western Europe, with a few narrow zones of distributional overlap, suggests that they are in competitive parapatry. (2) Two of these contact zones were studied; there was evidence of coexistence over periods of 2 years as well as habitat segregation. In both zones, the species segregated on litter thickness and humidity variables. (3) A simple analysis of spatial distribution showed that habitats visible in the field corresponded to the habitats selected by the species. Habitat selection was found throughout the annual life-cycle of the shrews. (4) In one contact zone, a removal experiment was performed to test whether habitat segregation is induced by interspecific interactions. The experiment showed that the species select habitats differentially when both are present and abandon habitat selection when their competitor is removed. (5) These results confirm the role of resource partitioning in promoting narrow rangesof distributional overlap between such parapatric species and qualitatively support the prediction of habitat selection theory that, in a two-species system, coexistence may be achieved by differential habitat selection to avoid competition. The results also support the view that the common shrew and Millet's shrew are in competitive parapatry.