Carrier relaxation, pseudogap, and superconducting gap in high-Tc cuprates: A Raman scattering study

We describe results of electronic Raman-scattering experiments in differently doped single crystals of Y-123 and Bi-2212. The comparison of AF insulating and metallic samples suggests that at least the low-energy part of the spectra originates predominantly from excitations of free carriers. We therefore propose an analysis of the data in terms of a memory function approach. Dynamical scattering rates and mass-enhancement factors for the carriers are obtained. In B2g symmetry the Raman data compare well to the results obtained from ordinary and optical transport. For underdoped materials the dc scattering rates in B1g symmetry become temperature independent and considerably larger than in B2g symmetry. This increasing anisotropy is accompanied by a loss of spectral weight in B2g symmetry in the range between the superconducting transition at Tc and a characteristic temperature T* of order room temperature which compares well with the pseudogap temperature found in other experiments. The energy range affected by the pseudogap is doping and temperature independent. The integrated spectral loss is approximately 25% in underdoped samples and becomes much weaker towards higher carrier concentration. In underdoped samples, superconductivity related features in the spectra can be observed only in B2g symmetry. The peak frequencies scale with Tc. We do not find a direct relation between the pseudogap and the superconducting gap.Comment: RevTeX, 21 pages, 24 gif figures. For PostScript with embedded eps figures, see http://www.wmi.badw-muenchen.de/~opel/k2.htm

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Do Femtonewton Forces Affect Genetic Function? A Review

Protein-Mediated DNA looping is intricately related to gene expression. Therefore any mechanical constraint that disrupts loop formation can play a significant role in gene regulation. Polymer physics models predict that less than a piconewton of force may be sufficient to prevent the formation of DNA loops. Thus, it appears that tension can act as a molecular switch that controls the much larger forces associated with the processive motion of RNA polymerase. Since RNAP can exert forces over 20 pN before it stalls, a ‘substrate tension switch’ could offer a force advantage of two orders of magnitude. Evidence for such a mechanism is seen in recent in vitro micromanipulation experiments. In this article we provide new perspective on existing theory and experimental data on DNA looping in vitro and in vivo . We elaborate on the connection between tension and a variety of other intracellular mechanical constraints including sequence specific curvature and supercoiling. In the process, we emphasize that the richness and versatility of DNA mechanics opens up a whole new paradigm of gene regulation to explore.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41816/1/10867_2005_Article_9002.pd

Active repression of RAR signaling is required for head formation

The retinoic acid receptors (RARs) recruit coactivator and corepressor proteins to activate or repress the transcription of target genes depending on the presence of retinoic acid (RA). Despite a detailed molecular understanding of how corepressor complexes function, there is no in vivo evidence to support a necessary function for RAR-mediated repression. Signaling through RARs is required for patterning along the anteroposterior (A-P) axis, particularly in the hindbrain and posterior, although the absence of RA is required for correct anterior patterning. Because RARs and corepressors are present in regions in which RA is absent, we hypothesized that repression mediated through unliganded RARs might be important for anterior patterning. To test this hypothesis, specific reagents were used that either reduce or augment RAR-mediated repression. Derepression of RAR signaling by expressing a dominant-negative corepressor resulted in embryos that exhibited phenotypes similar to those treated by RA. Anterior structures such as forebrain and cement gland were greatly reduced, as was the expression of molecular markers. Enhancement of target gene repression using an RAR inverse agonist resulted in up-regulation of anterior neural markers and expansion of anterior structures. Morpholino antisense oligonucleotide-mediated RARα loss-of-function phenocopied the effects of RA treatment and dominant-negative corepressor expression. Microinjection of wild-type or dominant-negative RARα rescued the morpholino phenotype, confirming that RAR is functioning anteriorly as a transcriptional repressor. Lastly, increasing RAR-mediated repression potentiated head-inducing activity of the growth factor inhibitor cerberus, whereas releasing RAR-mediated repression blocked cerberus from inducing ectopic heads. We conclude that RAR-mediated repression of target genes is critical for head formation. This requirement establishes an important biological role for active repression of target genes by nuclear hormone receptors and illustrates a novel function for RARs during vertebrate development

Combining intelligent agents and animation

Abstract. This paper reviews FreeWill and other AI architectures that have contributed to the ideas, which underlie it. “FreeWill ” proposes and implements a cognitive architecture designed for easy creation of animated scenes with many autonomous agents interacting in various ways. The generation of animated human figures especially in crowd scenes has many applications in such domains as the special effects industry, computer games or for the simulation of the evacuation from crowded areas. Currently such scenes have to be created by human animators using dedicated software packages. This is both expensive and time-consuming. FreeWill combines and extends two existing architectures – Funge’s cognitive architecture and the recent SAC concept. Additionally it puts emphasis on strong design and provides easy co-operation of different software packages