Optimized supernova constraints on dark energy evolution

A model-independent method to study the possible evolution of dark energy is presented. Optimal estimates of the dark energy equation of state w are obtained from current supernovae data from Riess et al. (2004) following a principal components approach. We assess the impact of varying the number of piecewise constant estimates of w using a model selection method, the Bayesian information criterion, and compare the most favored models with some parametrizations commonly used in the literature. Although data seem to prefer a cosmological constant, some models are only moderately disfavored by our selection criterion: a constant w, w linear in the scale factor, w linear in redshift and the two-parameter models introduced here. Among these, the models we find by optimization are slightly preferred. However, current data do not allow us to draw a conclusion on the possible evolution of dark energy. Interestingly, the best fits for all varying-w models exhibit a w<-1 at low redshifts.Comment: 6 pages, 4 figures; typos removed and reference added to match published versio

Global brain asymmetry is increased in schizophrenia and related to avolition

Objective: Schizophrenia may be the result of a failure of the normal lateralization process of the brain. However, whole-brain asymmetry has not been assessed up to date. Here we propose a novel measure of global brain asymmetry based on the Dice coefficient in order to quantify similarity between brain hemispheres. Method: Global gray and white matter asymmetry was calculated from high-resolution T1 structural images acquired from 24 patients with schizophrenia and 26 healthy controls, age- and sex-matched. Some of the analyses were replicated in a much larger sample (n = 759) obtained from open-access online databases. Results: Patients with schizophrenia had more global gray matter asymmetry than controls. Additionally, increased gray matter asymmetry was associated with avolition, whereas the inverse relationship was found for anxiety. These analyses were replicated in a larger sample and confirmed previous results. Conclusion: Our findings suggest that global gray matter asymmetry is related to the concept of developmental stability and is a useful indicator of perturbations during neurodevelopment

Asset Management in Volatile Markets

The 27th SUERF Colloquium in Munich in June 2008: New Trends in Asset Management: Exploring the Implications was already topical in the Summer of 2008. The subsequent dramatic events in the Autumn of 2008 made the presentations in Munich even more relevant to investors and bankers that want to understand what happens in their investment universe. In the present SUERF Study, we have collected a sample of outstanding colloquium contributions under the fitting headline: Asset Management in Volatile Markets.derivatives, financial innovation, asset management, finance-growth-nexus; Relative Value Strategy, Pair Trading, Slippage, Implementation Shortfall, Asset Management, Fin4Cast

The Effects of 5-Hydroxytryptophan in Combination with Different Fatty Acids on Gastrointestinal Functions: A Pilot Experiment

Background. Fat affects gastric emptying (GE). 5-Hydroxythryptophan (5-HTP) is involved in central and peripheral satiety mechanisms. Influence of 5-HTP in addition to saturated or monounsaturated fatty acids (FA) on GE and hormone release was investigated. Subjects/Methods. 24 healthy individuals (12f : 12m, 22-29 years, BMI 19-25.7 kg/m(2)) were tested on 4 days with either 5-HTP + short-chain saturated FA (butter), placebo + butter, 5-HTP + monounsaturated FA (olive oil), or placebo + olive oil in double-blinded randomized order. Two hours after FA/5-HTP or placebo intake, a C-13 octanoid acid test was conducted. Cortisol, serotonin, cholecystokinin (CCK), and ghrelin were measured, as were mood and GE. Results. GE was delayed with butter and was normal with olive (P < 0.05) but not affected by 5-HTP. 5-HTP supplementation did not affect serotonin levels. Food intake increased plasma CCK (F = 6.136; P < 0.05) irrespective of the FA. Ghrelin levels significantly decreased with oil/5-HTP (F = 9.166; P < 0.001). The diurnal cortisol profile was unaffected by FA or 5-HTP, as were ratings of mood, hunger, and stool urgency. Conclusion. Diverse FAs have different effects on GE and secretion of orexigenic and anorexigenic hormones. Supplementation of 5-HTP had no effect on plasma serotonin and central functions. Further studies are needed to explain the complex interplay

Cosmological stretching of perturbations on a cosmic string

We investigate the effects of cosmological expansion on the spectrum of small-scale structure on a cosmic string. We simulate the evolution of a string with two modes that differ in wavelength by one order of magnitude. Once the short mode is inside the horizon, we find that its physical amplitude remains unchanged, in spite of the fact that its comoving wavelength decreases as the longer mode enters the horizon. Thus the ratio of amplitude to wavelength for the short mode becomes larger than it would be in the absence of the long mode.Comment: 11 pages, 5 postscript figure

Mitmachen unbedingt erwünscht

Zunehmend halten neue Veranstaltungsformate und digitale Anwendungen Einzug in den Wissenstransfer. Durch die Förderung eines interaktiven Miteinanders können Teilnehmende zu Mitgestaltern werden

Structural Dynamics of the YidC:Ribosome Complex during Membrane Protein Biogenesis

Members of the YidC/Oxa1/Alb3 family universally facilitate membrane protein biogenesis, via mechanisms that have thus far remained unclear. Here, we investigated two crucial functional aspects: the interaction of YidC with ribosome: nascent chain complexes (RNCs) and the structural dynamics of RNC-bound YidC in nanodiscs. We observed that a fully exposed nascent transmembrane domain (TMD) is required for high-affinity YidC: RNC interactions, while weaker binding may already occur at earlier stages of translation. YidC efficiently catalyzed the membrane insertion of nascent TMDs in both fluid and gel phase membranes. Cryo-electron microscopy and fluorescence analysis revealed a conformational change in YidC upon nascent chain insertion: the essential TMDs 2 and 3 of YidC were tilted, while the amphipathic helix EH1 relocated into the hydrophobic core of the membrane. We suggest that EH1 serves as a mechanical lever, facilitating a coordinated movement of YidC TMDs to trigger the release of nascent chains into the membrane