Search for starless clumps in the ATLASGAL survey

In this study, we present an unbiased sample of the earliest stages of massive star formation across 20 square-degree of the sky. Within the region 10deg < l < 20deg and |b| < 1deg, we search the ATLASGAL survey at 870 micron for dense gas condensations. These clumps are carefully examined for indications of ongoing star formation using YSOs from the GLIMPSE source catalog as well as sources in the 24 micron MIPSGAL images, to search for starless clumps. We calculate the column densities as well as the kinematic distances and masses for sources where the v_lsr is known from spectroscopic observations. Within the given region, we identify 210 starless clumps with peak column densities > 1 x 10e23 cm^(-2). In particular, we identify potential starless clumps on the other side of the Galaxy. The sizes of the clumps range between 0.1 pc and 3 pc with masses between a few tens of solar masses up to several ten thousands of solar masses. Most of them may form massive stars, but in the 20 square-degree we only find 14 regions massive enough to form stars more massive than 20 solar masses and 3 regions with the potential to form stars more massive than 40 40 solar masses. The slope of the high-mass tail of the clump mass function for clumps on the near side of the Galaxy is 2.2 and, therefore, Salpeter-like. We estimate the lifetime of the most massive starless clumps to be 60000 yr. The sample offers a uniform selection of starless clumps. In the large area surveyed, we only find a few potential precursors of stars in the excess of 40 solar masses. It appears that the lifetime of these clumps is somewhat shorter than their free-fall times, although both values agree within the errors. In addition, these are ideal objects for detailed studies and follow-up observations.Comment: 15 pages plus appendix, in total 44 pages, accepted for publication in Astronomy & Astrophysics, full tables will be added soo

The Milky Way Project and ATLASGAL: The Distribution and Physical Properties of Cold Clumps Near Infrared Bubbles

We present a statistical study of the distribution and physical properties of cold, dense material in and around the inner Galactic Plane near-infrared bubbles as cataloged by the Milky Way Project citizen scientists. Using data from the Atacama Pathfinder Experiment (APEX) Telescope Large Area Survey of the Galaxy 870 μm survey, we show that 48 ± 2% of all cold clumps in the studied survey region (| l| ≤slant 65^\circ , | b| ≤slant 1^\circ ) are found in close proximity to a bubble, and 25 ± 2% appear directly projected toward a bubble rim. A two-point correlation analysis confirms the strong correlation of massive cold clumps with expanding bubbles. It shows an overdensity of clumps along bubble rims that grows with increasing bubble size, which shows how interstellar medium material is reordered on large scales by bubble expansion around regions of massive star formation. The highest column density clumps appear to be resistent to the expansion, remaining overdense toward the bubbles’ interior rather than being swept up by the expanding edge. Spectroscopic observations in ammonia show that cold dust clumps near bubbles appear to be denser, hotter, and more turbulent than those in the field, offering circumstantial evidence that bubble-associated clumps are more likely to be forming stars. These observed differences in physical conditions persist beyond the region of the bubble rims

Structural Basis for Inhibition Promiscuity of Dual Specific Thrombin and Factor Xa Blood Coagulation Inhibitors

AbstractBackground: A major current focus of pharmaceutical research is the development of selective inhibitors of the blood coagulation enzymes thrombin or factor Xa to be used as orally bioavailable anticoagulant drugs in thromboembolic disorders and in the prevention of venous and arterial thrombosis. Simultaneous direct inhibition of thrombin and factor Xa by synthetic proteinase inhibitors as a novel approach to antithrombotic therapy could result in potent anticoagulants with improved pharmacological properties.Results: The binding mode of such dual specific inhibitors of thrombin and factor Xa was determined for the first time by comparative crystallography using human α-thrombin, human des-Gla (1–44) factor Xa and bovine trypsin as the ligand receptors. The benzamidine-based inhibitors utilize two different conformations for the interaction with thrombin and factor Xa/trypsin, which are evoked by the steric requirements of the topologically different S2 subsites of the enzymes. Compared to the unliganded forms of the proteinases, ligand binding induces conformational adjustments of thrombin and factor Xa active site residues indicative of a pronounced induced fit mechanism.Conclusion: The structural data reveal the molecular basis for a desired unselective inhibition of the two key components of the blood coagulation cascade. The 4-(1-methyl-benzimidazole-2-yl)-methylamino-benzamidine moieties of the inhibitors are able to fill both the small solvent accessible as well as the larger hydrophobic S2 pockets of factor Xa and thrombin, respectively. Distal fragments of the inhibitors are identified which fit into both the cation hole/aromatic box of factor Xa and the hydrophobic aryl binding site of thrombin. Thus, binding constants in the medium-to-low nanomolar range are obtained against both enzymes

Teachers' perceptions of behavioral problems in Dutch primary education pupils:The role of relative age

A growing number of studies suggest that relatively young behavior of pupils gives them a much greater likelihood of being diagnosed with a disorder such as ADHD. This 'relative age effect' has also been demonstrated for special educational needs, learning difficulties, being bullied, and so on. The current study investigated the relationship between relative age of pupils in primary education and teachers' perception of their behavior. The study sample included 1973 pupils, aged between 6 and 12. Six linear mixed models were carried out with birth day in a year as predictor variable and 'total problem score', 'problems with hyperactivity', 'behavioral problems', 'emotional problems', 'problems with peers' and 'pro-social behavior' as dependent variables. Random intercepts were added for school and teacher level. Cluster-mean centering disaggregated between-school effects and within-school effects. We found no associations between relative age of pupils and teacher perceptions of their behavior. Several explanations are postulated to account for these findings which contradict prior studies on relative age effects

Do troublesome pupils impact teacher perception of the behaviour of their classmates?

The widely supported wish for more inclusive education places ever greater expectations on teachers’ abilities to teach all children, including those with special needs and challenging behaviours. The present study aimed at the question whether teachers judge pupil behaviour more negatively if there are more children with difficult behaviour in class. The teachers of 184 classes in 31 regular primary schools were asked to complete the Strength and Difficulties Questionnaire (SDQ-L) for 3649 pupils. Six linear mixed models were carried out with as independent variable the number of pupils that teachers perceived to have ‘abnormal behaviour’, and the class mean without these pupils as the dependent variable. For all SDQ-L subscales – emotional problems, behavioural problems, problems with hyperactivity, problems with peers, poor prosocial behaviour and total problems – the number of pupils perceived as problematic was associated with less favourable teacher perceptions of the rest of the class. The results of this study are a plea for a contextual perspective on pupil behaviour in class, both where teachers are asked to report on individual pupils, as well as where interventions are done on emotional and behavioural problems in class

The relative impact of school‐wide positive behavior support on teachers’ perceptions of student behavior across schools, teachers, and students

School‐wide positive behavior support (SWPBS) is a systemic approach for implementing a proactive schoolwide discipline and for improving students’ academic and behavioral outcomes by targeting the school’s organizational and social culture. With a multilevel approach, the present study evaluates the relative effectiveness of SWPBS on teachers’ perceptions of the student behavior (N = 3,295) across schools, teachers, and children using a multilevel approach. We assessed teacher perception of student problem behavior five times during a 3‐year implementation of SWPBS in 23 Dutch schools. Multilevel analyses not only revealed a small increase in perceived prosocial behavior and a small decrease in problems with peers, but also different effects across children, teachers, and schools. Effects were stronger for girls and for students with higher severity of perceived problems at baseline. At teachers’ level, higher mean baseline severity of perceived problems was associated with the reduced impact of SWPBS on perceived emotional problems and problems with peers. At the school level, effects were stronger for regular schools as compared with special needs schools

LEGO-II. A 3 mm molecular line study covering 100 pc of one of the most actively star-forming portions within the Milky Way disc

The current generation of (sub)mm-telescopes has allowed molecular line emission to become a major tool for studying the physical, kinematic, and chemical properties of extragalactic systems, yet exploiting these observations requires a detailed understanding of where emission lines originate within the Milky Way. In this paper, we present 60 arcsec (∼3 pc) resolution observations of many 3 mm band molecular lines across a large map of the W49 massive star-forming region (∼100 pc × 100 pc at 11 kpc), which were taken as part of the ‘LEGO’ IRAM-30m large project. We find that the spatial extent or brightness of the molecular line transitions are not well correlated with their critical densities, highlighting abundance and optical depth must be considered when estimating line emission characteristics. We explore how the total emission and emission efficiency (i.e. line brightness per H2 column density) of the line emission vary as a function of molecular hydrogen column density and dust temperature. We find that there is not a single region of this parameter space responsible for the brightest and most efficiently emitting gas for all species. For example, we find that the HCN transition shows high emission efficiency at high column density (1022 cm−2) and moderate temperatures (35 K), whilst e.g. N2H+ emits most efficiently towards lower temperatures (1022 cm−2; <20 K). We determine XCO(1−0) ∼ 0.3 × 1020 cm−2 (K km s−1) −1, and αHCN(1−0) ∼ 30 M (K km s−1 pc2) −1, which both differ significantly from the commonly adopted values. In all, these results suggest caution should be taken when interpreting molecular line emission

Characterisation of the MALT90 Survey and the Mopra Telescope at 90 GHz

We characterise the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90) and the Mopra telescope at 90 GHz. We combine repeated position-switched observations of the source G300.968+01.145 with a map of the same source in order to estimate the pointing reliability of the position-switched observations and, by extension, the MALT90 survey; we estimate our pointing uncertainty to be 8 arcsec. We model the two strongest sources of systematic gain variability as functions of elevation and time-of-day and quantify the remaining absolute flux uncertainty. Corrections based on these two variables reduce the scatter in repeated observations from 12%–25% down to 10%–17%. We find no evidence for intrinsic source variability in G300.968+01.145. For certain applications, the corrections described herein will be integral for improving the absolute flux calibration of MALT90 maps and other observations using the Mopra telescope at 90 GHz

Structural basis of subtype-selective competitive antagonism for GluN2C/2D-containing NMDA receptors.

N-Methyl-D-aspartate receptors (NMDARs) play critical roles in the central nervous system. Their heterotetrameric composition generates subtypes with distinct functional properties and spatio-temporal distribution in the brain, raising the possibility for subtype-specific targeting by pharmacological means for treatment of neurological diseases. While specific compounds for GluN2A and GluN2B-containing NMDARs are well established, those that target GluN2C and GluN2D are currently underdeveloped with low potency and uncharacterized binding modes. Here, using electrophysiology and X-ray crystallography, we show that UBP791 ((2S*,3R*)-1-(7-(2-carboxyethyl)phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid) inhibits GluN2C/2D with 40-fold selectivity over GluN2A-containing receptors, and that a methionine and a lysine residue in the ligand binding pocket (GluN2D-Met763/Lys766, GluN2C-Met736/Lys739) are the critical molecular elements for the subtype-specific binding. These findings led to development of UBP1700 ((2S*,3R*)-1-(7-(2-carboxyvinyl)phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid) which shows over 50-fold GluN2C/2D-selectivity over GluN2A with potencies in the low nanomolar range. Our study shows that the L-glutamate binding site can be targeted for GluN2C/2D-specific inhibition