510 research outputs found
ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets
The protoplanetary system HD 169142 is one of the few cases where a potential candidate protoplanet has recently been detected by direct imaging in the near-infrared. To study the interaction between the protoplanet and the disk itself, observations of the gas and dust surface density structure are needed. This paper reports new ALMA observations of the dust continuum at 1.3 mm, 12CO, 13CO, and C18O J = 2−1 emission from the system HD 169142 (which is observed almost face-on) at an angular resolution of ∼0.3"×0.2′′ (∼35 × 20 au). The dust continuum emission reveals a double-ring structure with an inner ring between 0.17"−0.28" (∼20−35 au) and an outer ring between 0.48−0.64 (∼56−83 au). The size and position of the inner ring is in good agreement with previous polarimetric observations in the near-infrared and is consistent with dust trapping by a massive planet. No dust emission is detected inside the inner dust cavity (R μm size). Using the thermo-chemical disk code dali, we modeled the continuum and the CO isotopolog emission to quantitatively measure the gas and dust surface densities. The resulting gas surface density is reduced by a factor of ∼30−40 inward of the dust gap. The gas and dust distribution indicate that two giant planets shape the disk structure through dynamical clearing (dust cavity and gap) and dust trapping (double-ring dust distribution)
Probing midplane CO abundance and gas temperature with DCO+ in the protoplanetary disk around HD 169142
Context. Physical and chemical processes in protoplanetary disks affect the disk structure and the midplane environment within which planets form. The simple deuterated molecular cation DCO+ has been proposed to act as a tracer of the disk midplane conditions. Aims. This work aims to understand which midplane conditions are probed by the DCO+ emission in the disk around the Herbig Ae star HD 169142. We explore the sensitivity of the DCO+ formation pathways to gas temperature and CO abundance. Methods. The DCO+ J = 3−2 transition was observed with Atacama Large Millimeter/submillimeter Array at a spatial resolution of ~0.3′′ (35 AU at 117 pc). We modeled the DCO+ emission in HD 169142 with a physical disk structure adapted from the literature, and employed a simple deuterium chemical network to investigate the formation of DCO+ through the cold deuterium fractionation pathway via H2D+. Parameterized models are used to modify the gas temperature and CO abundance structure of the disk midplane to test their effect on DCO+ production. Contributions from the warm deuterium fractionation pathway via CH2D+ are approximated using a constant abundance in the intermediate disk layers. Results. The DCO+ line is detected in the HD 169142 disk with a total integrated line flux of 730 ± 73 mJy km s−1. The radial intensity profile reveals a warm, inner component of the DCO+ emission at radii ≲30 AU and a broad, ring-like structure from ~50–230 AU with a peak at 100 AU just beyond the edge of the millimeter grain distribution. Parameterized models show that alterations to the midplane gas temperature and CO abundance are both needed to recover the observed DCO+ radial intensity profile. The alterations are relative to the fiducial physical structure of the literature model constrained by dust and CO observations. The best-fit model contains a shadowed, cold midplane in the region z∕r 120 AU. The warm deuterium fractionation pathway is implemented as a constant DCO+ abundance of 2.0 × 10−12 between 30–70 K and contributes >85% to the DCO+ emission at r < 83 AU in the best-fit model. Conclusions. The DCO+ emission probes a reservoir of cold material in the HD 169142 outer disk that is not probed by the millimeter continuum, the spectral energy distribution, nor the emission from the 12 CO, 13 CO, or C18O J = 2−1 lines. The DCO+ emission is a sensitive probe of gas temperature and CO abundance near the disk midplane and provides information about the outer disk beyond the millimeter continuum distribution that is largely absent in abundant gaseous tracers such as CO isotopologues
Pregnant women with bronchial asthma benefit from progressive muscle relaxation: A randomized, prospective, controlled trial
Background: Asthma is a serious medical problem in pregnancy and is often associated with stress, anger and poor quality of life. The aim of this study was to determine the efficacy of progressive muscle relaxation (PMR) on change in blood pressure, lung parameters, heart rate, anger and health-related quality of life in pregnant women with bronchial asthma. Methods: We treated a sample of 64 pregnant women with bronchial asthma from the local population in an 8-week randomized, prospective, controlled trial. Thirty-two were selected for PMR, and 32 received a placebo intervention. The systolic blood pressure, forced expiratory volume in the first second, peak expiratory flow and heart rate were tested, and the State-Trait Anger Expression Inventory and Health Survey (SF-36) were employed. Results: According to the intend-to-treat principle, a significant reduction in systolic blood pressure and a significant increase in both forced expiratory volume in the first second and peak expiratory flow were observed after PMR. The heart rate showed a significant increase in the coefficient of variation, root mean square of successive differences and high frequency ranges, in addition to a significant reduction in low and middle frequency ranges. A significant reduction on three of five State-Trait Anger Expression Inventory scales, and a significant increase on seven of eight SF-36 scales were observed. Conclusions: PMR appears to be an effective method to improve blood pressure, lung parameters and heart rate, and to decrease anger levels, thus enhancing health-related quality of life in pregnant women with bronchial asthma. Copyright (c) 2006 S. Karger AG, Basel
Autism as a disorder of neural information processing: directions for research and targets for therapy
The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself
Corporate boards and the performance of Asian firms: A meta-analysis
The prevalence of ownership concentration in Asian firms presents a challenge to the influential agency theory-based understanding of the role of corporate boards. In this paper we develop and test hypotheses about board attributes and firm performance that reflect Asian institutional conditions. We present the first meta-analysis of the relationship between board attributes and performance of Asian firms using a varied set of meta-analytical techniques on a database of 86 studies covering nine Asian countries. First, we find that board structure and composition preferences are influenced by the identity of the concentrated owner. Second, consistent with US data, we find very limited evidence of a direct relationship between board attributes and firm financial performance in the Asian context. Third, we find that the relationship between board structure and composition and firm performance is mediated by the revealed strategic preferences of Asian firms specifically by the level of R&D investment
AHR2 Mutant Reveals Functional Diversity of Aryl Hydrocarbon Receptors in Zebrafish
The aryl hydrocarbon receptor (AHR) is well known for mediating the toxic effects of TCDD and has been a subject of intense research for over 30 years. Current investigations continue to uncover its endogenous and regulatory roles in a wide variety of cellular and molecular signaling processes. A zebrafish line with a mutation in ahr2 (ahr2hu3335), encoding the AHR paralogue responsible for mediating TCDD toxicity in zebrafish, was developed via Targeting Induced Local Lesions IN Genomes (TILLING) and predicted to express a non-functional AHR2 protein. We characterized AHR activity in the mutant line using TCDD and leflunomide as toxicological probes to investigate function, ligand binding and CYP1A induction patterns of paralogues AHR2, AHR1A and AHR1B. By evaluating TCDD-induced developmental toxicity, mRNA expression changes and CYP1A protein in the AHR2 mutant line, we determined that ahr2hu3335 zebrafish are functionally null. In silico modeling predicted differential binding of TCDD and leflunomide to the AHR paralogues. AHR1A is considered a non-functional pseudogene as it does not bind TCCD or mediate in vivo TCDD toxicity. Homology modeling, however, predicted a ligand binding conformation of AHR1A with leflunomide. AHR1A-dependent CYP1A immunohistochemical expression in the liver provided in vivo confirmation of the in silico docking studies. The ahr2hu3335 functional knockout line expands the experimental power of zebrafish to unravel the role of the AHR during development, as well as highlights potential activity of the other AHR paralogues in ligand-specific toxicological responses
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
How Are ‘Barack Obama’ and ‘President Elect’ Differentially Stored in the Brain? An ERP Investigation on the Processing of Proper and Common Noun Pairs
BACKGROUND:One of the most debated issues in the cognitive neuroscience of language is whether distinct semantic domains are differentially represented in the brain. Clinical studies described several anomic dissociations with no clear neuroanatomical correlate. Neuroimaging studies have shown that memory retrieval is more demanding for proper than common nouns in that the former are purely arbitrary referential expressions. In this study a semantic relatedness paradigm was devised to investigate neural processing of proper and common nouns. METHODOLOGY/PRINCIPAL FINDINGS:780 words (arranged in pairs of Italian nouns/adjectives and the first/last names of well known persons) were presented. Half pairs were semantically related ("Woody Allen" or "social security"), while the others were not ("Sigmund Parodi" or "judicial cream"). All items were balanced for length, frequency, familiarity and semantic relatedness. Participants were to decide about the semantic relatedness of the two items in a pair. RTs and N400 data suggest that the task was more demanding for common nouns. The LORETA neural generators for the related-unrelated contrast (for proper names) included the left fusiform gyrus, right medial temporal gyrus, limbic and parahippocampal regions, inferior parietal and inferior frontal areas, which are thought to be involved in the conjoined processing a familiar face with the relevant episodic information. Person name was more emotional and sensory vivid than common noun semantic access. CONCLUSIONS/SIGNIFICANCE:When memory retrieval is not required, proper name access (conspecifics knowledge) is not more demanding. The neural generators of N400 to unrelated items (unknown persons and things) did not differ as a function of lexical class, thus suggesting that proper and common nouns are not treated differently as belonging to different grammatical classes
Ownership identity, strategy and performance:business group affiliates versus independent firms in India
We consider whether the impact of entrepreneurial orientation on business performance is moderated by the company affiliation with business groups. Within business groups, we explore the trade-off between inter-firm insurance that enables risk-taking, and inefficient resource allocation. Risk-taking in group affiliated firms leads to higher performance, compared to independent firms, but the impact of proactivity is attenuated. Utilizing Indian data, we show that risk-taking may undermine rather than improve business performance, but this effect is not present in business groups. Proactivity enhances performance, but less so in business groups. Firms can also enhance performance by technological knowledge acquisition, but these effects are not significantly different for various ownership categories
Estrogen Receptor Beta rs1271572 Polymorphism and Invasive Ovarian Carcinoma Risk: Pooled Analysis within the Ovarian Cancer Association Consortium
The association of ovarian carcinoma risk with the polymorphism rs1271572 in the estrogen receptor beta (ESR2) gene was examined in 4946 women with primary invasive ovarian carcinoma and 6582 controls in a pooled analysis of ten case-control studies within the Ovarian Cancer Association Consortium (OCAC). All participants were non-Hispanic white women. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression adjusted for site and age. Women with the TT genotype were at increased risk of ovarian carcinoma compared to carriers of the G allele (OR = 1.10; 95%; CI: 1.01–1.21; p = 0.04); the OR was 1.09 (CI: 0.99–1.20; p = 0.07) after excluding data from the center (Hawaii) that nominated this SNP for OCAC genotyping A stronger association of rs1271572 TT versus GT/GG with risk was observed among women aged ≤50 years versus older women (OR = 1.35; CI: 1.12–1.62; p = 0.002; p for interaction = 0.02) that remained statistically significant after excluding Hawaii data (OR = 1.34; CI: 1.11–1.61; p = 0.009). No heterogeneity of the association was observed by study, menopausal status, gravidity, parity, use of contraceptive or menopausal hormones, tumor histological type, or stage at diagnosis. This pooled analysis suggests that rs1271572 might influence the risk of ovarian cancer, in particular among younger women
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