A dusty torus around the luminous young star LkHa 101

A star forms when a cloud of dust and gas collapses. It is generally believed that this collapse first produces a flattened rotating disk, through which matter is fed onto the embryonic star at the center of the disk. When the temperature and density at the center of the star pass a critical threshold, thermonuclear fusion begins. The remaining disk, which can still contain up to 0.3 times the mass of the star, is then sculpted and eventually dissipated by the radiation and wind from the newborn star. Unfortunately this picture of the structure and evolution of the disk remains speculative because of the lack of morphological data of sufficient resolution and uncertainties regarding the underlying physical processes. Here we present resolved images of a young star, LkHa 101 in which the structure of the inner accretion disk is resolved. We find that the disk is almost face-on, with a central gap (or cavity) and a hot inner edge. The cavity is bigger than previous theoretical predictions, and we infer that the position of the inner edge is probably determined by sublimation of dust grains by direct stellar radiation, rather than by disk reprocessing or the viscous heating processes as usually assumed.Comment: 7 pages, 1 figure. Appears in Nature, 22 Feb, 2001 (Vol 409

Circumstellar disks and planets. Science cases for next-generation optical/infrared long-baseline interferometers

We present a review of the interplay between the evolution of circumstellar disks and the formation of planets, both from the perspective of theoretical models and dedicated observations. Based on this, we identify and discuss fundamental questions concerning the formation and evolution of circumstellar disks and planets which can be addressed in the near future with optical and infrared long-baseline interferometers. Furthermore, the importance of complementary observations with long-baseline (sub)millimeter interferometers and high-sensitivity infrared observatories is outlined.Comment: 83 pages; Accepted for publication in "Astronomy and Astrophysics Review"; The final publication is available at http://www.springerlink.co

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy

A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.Comment: Published in Physical Review Letter

Compressed representation of a partially defined integer function over multiple arguments

In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

Red Fox Vulpes vulpes (L., 1758) as a Bioindicator of Mercury Contamination in Terrestrial Ecosystems of North-Western Poland

In this study, we determined the concentrations of total mercury (Hg) in samples of liver, kidney and skeletal muscle of 27 red foxes Vulpes vulpes (L., 1758) from north-western Poland, and examined the morphometric characteristics of the collected specimens. The analysis also included the relationship between Hg concentration and the fox size, and the suitability of individual organs as bioindicators in indirect evaluation of environmental mercury contamination. Determination of Hg concentration was performed by atomic absorption spectroscopy. In the analysed samples, the Hg concentration was low and the maximum value did not exceed 0.85 mgHg/kg dry weight (dw). There were no significant differences in Hg concentrations in the analysed material between males and females or between immature and adult groups. The median concentrations of Hg in the liver, kidney and skeletal muscle were 0.22, 0.11 and 0.05 mgHg/kg dw, respectively. The correlation coefficients were significant between the concentrations of mercury in the liver, kidney and skeletal muscle (positive) and between the kidney Hg concentration and kidney mass (negative). Taking into account our results and findings of other authors, it may be argued that the red fox exhibits a measurable response to mercury environmental pollution and meets the requirements of a bioindicator

Radio & Optical Interferometry: Basic Observing Techniques and Data Analysis

Astronomers usually need the highest angular resolution possible, but the blurring effect of diffraction imposes a fundamental limit on the image quality from any single telescope. Interferometry allows light collected at widely-separated telescopes to be combined in order to synthesize an aperture much larger than an individual telescope thereby improving angular resolution by orders of magnitude. Radio and millimeter wave astronomers depend on interferometry to achieve image quality on par with conventional visible and infrared telescopes. Interferometers at visible and infrared wavelengths extend angular resolution below the milli-arcsecond level to open up unique research areas in imaging stellar surfaces and circumstellar environments. In this chapter the basic principles of interferometry are reviewed with an emphasis on the common features for radio and optical observing. While many techniques are common to interferometers of all wavelengths, crucial differences are identified that will help new practitioners avoid unnecessary confusion and common pitfalls. Concepts essential for writing observing proposals and for planning observations are described, depending on the science wavelength, angular resolution, and field of view required. Atmospheric and ionospheric turbulence degrades the longest-baseline observations by significantly reducing the stability of interference fringes. Such instabilities represent a persistent challenge, and the basic techniques of phase-referencing and phase closure have been developed to deal with them. Synthesis imaging with large observing datasets has become a routine and straightforward process at radio observatories, but remains challenging for optical facilities. In this context the commonly-used image reconstruction algorithms CLEAN and MEM are presented. Lastly, a concise overview of current facilities is included as an appendix.Comment: 45 pages, 14 Figures; an abridged version of a chapter to appear in Volume 2 of Planets, Stars and Stellar Systems, to be published in 2011 by Springe

Pharmacometabolomics of Response to Sertraline and to Placebo in Major Depressive Disorder - Possible Role for Methoxyindole Pathway

10.1371/journal.pone.0068283PLoS ONE87-POLN

Mutations disrupting neuritogenesis genes confer risk for cerebral palsy

In addition to commonly associated environmental factors, genomic factors may cause cerebral palsy. We performed whole-exome sequencing of 250 parent-offspring trios, and observed enrichment of damaging de novo mutations in cerebral palsy cases. Eight genes had multiple damaging de novo mutations; of these, two (TUBA1A and CTNNB1) met genome-wide significance. We identified two novel monogenic etiologies, FBXO31 and RHOB, and showed that the RHOB mutation enhances active-state Rho effector binding while the FBXO31 mutation diminishes cyclin D levels. Candidate cerebral palsy risk genes overlapped with neurodevelopmental disorder genes. Network analyses identified enrichment of Rho GTPase, extracellular matrix, focal adhesion and cytoskeleton pathways. Cerebral palsy risk genes in enriched pathways were shown to regulate neuromotor function in a Drosophila reverse genetics screen. We estimate that 14% of cases could be attributed to an excess of damaging de novo or recessive variants. These findings provide evidence for genetically mediated dysregulation of early neuronal connectivity in cerebral palsy

Ceruloplasmin Deficiency Reduces Levels of Iron and BDNF in the Cortex and Striatum of Young Mice and Increases Their Vulnerability to Stroke

Ceruloplasmin (Cp) is an essential ferroxidase that plays important roles in cellular iron trafficking. Previous findings suggest that the proper regulation and subcellular localization of iron are very important in brain cell function and viability. Brain iron dyshomeostasis is observed during normal aging, as well as in several neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's diseases, coincident with areas more susceptible to insults. Because of their high metabolic demand and electrical excitability, neurons are particularly vulnerable to ischemic injury and death. We therefore set out to look for abnormalities in the brain of young adult mice that lack Cp. We found that iron levels in the striatum and cerebral cortex of these young animals are significantly lower than wild-type (WT) controls. Also mRNA levels of the neurotrophin brain derived neurotrophic factor (BDNF), known for its role in maintenance of cell viability, were decreased in these brain areas. Chelator-mediated depletion of iron in cultured neural cells resulted in reduced BDNF expression by a posttranscriptional mechanism, suggesting a causal link between low brain iron levels and reduced BDNF expression. When the mice were subjected to middle cerebral artery occlusion, a model of focal ischemic stroke, we found increased brain damage in Cp-deficient mice compared to WT controls. Our data indicate that lack of Cp increases neuronal susceptibility to ischemic injury by a mechanism that may involve reduced levels of iron and BDNF

Enhanced Fear Expression in a Psychopathological Mouse Model of Trait Anxiety: Pharmacological Interventions

The propensity to develop an anxiety disorder is thought to be determined by genetic and environmental factors. Here we investigated the relationship between a genetic predisposition to trait anxiety and experience-based learned fear in a psychopathological mouse model. Male CD-1 mice selectively bred for either high (HAB), or normal (NAB) anxiety-related behaviour on the elevated plus maze were subjected to classical fear conditioning. During conditioning both mouse lines showed increased fear responses as assessed by freezing behaviour. However, 24 h later, HAB mice displayed more pronounced conditioned responses to both a contextual or cued stimulus when compared with NAB mice. Interestingly, 6 h and already 1 h after fear conditioning, freezing levels were high in HAB mice but not in NAB mice. These results suggest that trait anxiety determines stronger fear memory and/or a weaker ability to inhibit fear responses in the HAB line. The enhanced fear response of HAB mice was attenuated by treatment with either the α2,3,5-subunit selective benzodiazepine partial agonist L-838,417, corticosterone or the selective neurokinin-1 receptor antagonist L-822,429. Overall, the HAB mouse line may represent an interesting model (i) for identifying biological factors underlying misguided conditioned fear responses and (ii) for studying novel anxiolytic pharmacotherapies for patients with fear-associated disorders, including post-traumatic stress disorder and phobias