Chiral supersymmetric pp-wave solutions of IIA supergravity

We describe solutions of type IIA (N=2, D=10) supergravity built under the assumption of the existence of at least one residual chiral supersymmetry. Their geometry is of pp-wave type. Explicit parametrization of the metric and matter field components, in terms of Killing spinors and arbitrary functions, is provided.Comment: LaTeX file, 10 page

Accelerometer use in young people with Down syndrome: A preliminary cross-validation and reliability study

Background Inadequate physical activity is a problem for people with Down syndrome and objective monitoring using accelerometers may be inaccurate in this population. Method This was a cross-validation and reliability study comparing two triaxial accelerometers (the SenseWear and RT3) to a criterion measure (the OxyCon Mobile) in 10 young people (M age = 20 ± 2) with Down syndrome. A ROC curve analysis was conducted to determine intensity thresholds from RT3 activity counts. Results During self-selected pace walking, the accelerometers overestimated energy expenditure and had large limits of agreement (SenseWear: −0.5–3.6 METs; RT3: −0.2–2.7 METs). At this pace, SenseWear armband step counts were highly correlated with observed steps (r = .98) but underestimated steps by up to 12%. We developed RT3 thresholds that demonstrated good to excellent sensitivity and specificity in classifying physical activity intensity. Conclusions SenseWear steps and RT3 activity count thresholds can be used to monitor physical activity in young people with Down syndrome, although energy expenditure estimates should be used with caution in this population

The PdBI Arcsecond Whirlpool Survey (PAWS): The Role of Spiral Arms in Cloud and Star Formation

This is the final version of the article. Available from American Astronomical Society via the DOI in this record.The process that leads to the formation of the bright star-forming sites observed along prominent spiral arms remains elusive. We present results of a multi-wavelength study of a spiral arm segment in the nearby grand-design spiral galaxy M51 that belongs to a spiral density wave and exhibits nine gas spurs. The combined observations of the (ionized, atomic, molecular, dusty) interstellar medium with star formation tracers (H ii regions, young <10 Myr stellar clusters) suggest (1) no variation in giant molecular cloud (GMC) properties between arm and gas spurs, (2) gas spurs and extinction feathers arising from the same structure with a close spatial relation between gas spurs and ongoing/recent star formation (despite higher gas surface densities in the spiral arm), (3) no trend in star formation age either along the arm or along a spur, (4) evidence for strong star formation feedback in gas spurs, (5) tentative evidence for star formation triggered by stellar feedback for one spur, and (6) GMC associations being not special entities but the result of blending of gas arm/spur cross sections in lower resolution observations. We conclude that there is no evidence for a coherent star formation onset mechanism that can be solely associated with the presence of the spiral density wave. This suggests that other (more localized) mechanisms are important to delay star formation such that it occurs in spurs. The evidence of star formation proceeding over several million years within individual spurs implies that the mechanism that leads to star formation acts or is sustained over a longer timescale.S.E.M. and M.Q. acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) via grant SCHI 536/7-2 as part of the priority program SPP 1573 "ISM-SPP: Physics of the Interstellar Medium." C.L.D. acknowledges funding from the European Research Council for the FP7 ERC starting grant project LOCALSTAR. J.P. acknowledges support from the CNRS programme Physique et Chimie du Milieu Interstellaire (PCMI). M.Q. acknowledges the International Max Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg (IMPRS-HD). S.G.B. thanks support from Spanish grant AYA2012-32295. We acknowledge financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Unions Seventh Framework Programme FP7/2007-2013/ under REA grant agreement number PITN-GA-2011-289313. E.S. thanks NRAO for their support and hospitality during her visits in Socorro. E.S. thanks the Kavli Institute for Theoretical Physics for hospitality during the writing of this paper. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain)

Gravitational torques imply molecular gas inflow towards the nucleus of M 51

PublishedJournal Article© 2016 ESO.The transport of gas towards the centre of galaxies is critical for black hole feeding and, indirectly, it can control active galactic nucleus (AGN) feedback. We have quantified the molecular gas inflow in the central R< 1 kpc of M 51 to be 1 M⊙/yr, using a new gravitational torque map and the molecular gas traced by the Plateau de Bure Interferometer Arcsecond Whirlpool Survey (PAWS). The nuclear stellar bar is responsible for this gas inflow. We also used torque profiles to estimate the location of dynamical resonances, and the results suggest a corotation for the bar CRbar ∼ 20″, and a corotation for the spiral CRsp ∼ 100″. We demonstrate how important it is to correct 3.6 μm images for dust emission when gravitational torques are to be computed, and we examine further sources of uncertainty. Our observational measurement of gas inflow can be compared with nuclear molecular outflow rates and provide useful constraints for numerical simulations.The authors would like to thank the anonymous referee for a helpful report, as well as Daniela Calzetti, Nick Z. Scoville and Mari Polletta for making the HST/F190N mosaic available to us. We also appreciate valuable comments from Françoise Combes and Sebastian Haan. We acknowledge financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007- 2013/ under REA grant agreement number PITN-GA-2011-289313. M.Q. acknowledges the International Max Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg (IMPRS-HD). S.G.B. thanks support from Spanish grant AYA2012-32295. J.P. acknowledges support from the CNRS programme “Physique et Chimie du Milieu Interstellaire” (PCMI). M.Q., S.E.M., D.C. and A.H. acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) via grants SCHI 536/7-2,SCHI 536/5-1, and SCHI 536/7-1 as part of the priority program SPP 1573 “ISM-SPP: Physics of the Interstellar Medium”

Short GMC lifetimes: an observational estimate with the PdBI Arcsecond Whirlpool Survey (PAWS)

PublishedJournal ArticleWe describe and execute a novel approach to observationally estimate the lifetimes of giant molecular clouds (GMCs). We focus on the cloud population between the two main spiral arms in M51 (the inter-arm region) where cloud destruction via shear and star formation feedback dominates over formation processes. By monitoring the change in GMC number densities and properties across the inter-arm, we estimate the lifetime as a fraction of the inter-arm travel time. We find that GMC lifetimes in M51's inter-arm are finite and short, 20-30 Myr. Over most of the region under investigation shear appears to regulate the lifetime. As the shear timescale increases with galactocentric radius, we expect cloud destruction to switch primarily to feedback at larger radii. We identify a transition from shear- to feedback-dominated disruption, finding that shear is more efficient at dispersing clouds, whereas feedback transforms the population, e.g., by fragmenting high-mass clouds into lower mass pieces. Compared to the characteristic timescale for molecular hydrogen in M51, our short lifetimes suggest that gas can remain molecular while clouds disperse and reassemble. We propose that galaxy dynamics regulates the cycling of molecular material from diffuse to bound (and ultimately star-forming) objects, contributing to long observed molecular depletion times in normal disk galaxies. We also speculate that, in extreme environments like elliptical galaxies and concentrated galaxy centers, star formation can be suppressed when the shear timescale is short enough that some clouds will not survive to form stars.We thank the IRAM staff for their support during the observations with the Plateau de Bure interferometer and the 30 m telescope. S.E.M., D.C., and A.H. acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) via grants SCHI 536/7-2, SCHI 536/5-1, and SCHI 536/7-1 as part of the priority program SPP 1573 “ISM-SPP: Physics of the Interstellar Medium.” C.L.D. acknowledges funding from the European Research Council for the FP7 ERC starting grant project LOCALSTAR. T.A.T. acknowledges support from NASA grant number NNX10AD01G. J.P. acknowledges support from the CNRS program “Physique et Chimie du Milieu Interstellaire” (PCMI). M.Q. acknowledges financial support to the DAGAL network from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007-2013/ under REA grant agreement number PITN-GA-2011-289313

The PdBI Arcsecond Whirlpool Survey (PAWS): Multi-phase cold gas kinematic of M51

This is the final version of the article. Available from the publisher via the DOI in this record.The kinematic complexity and the favorable position of M51 on the sky make this galaxy an ideal target to test different theories of spiral arm dynamics. Taking advantage of the new high-resolution PdBI Arcsecond Whirlpool Survey data, we undertake a detailed kinematic study of M51 to characterize and quantify the origin and nature of the non-circular motions. Using a tilted-ring analysis supported by several other archival data sets, we update the estimation of M51's position angle (P.A. = (173 ± 3)°) and inclination (i = (22 ± 5)°). Harmonic decomposition of the high-resolution (∼40 pc) CO velocity field shows the first kinematic evidence of an m = 3 wave in the inner disk of M51 with a corotation at R CR, m = 3 = 1.1 ± 0.1 kpc and a pattern speed of Ωp, m = 3 ≈ 140 km s -1 kpc-1. This mode seems to be excited by the nuclear bar, while the beat frequencies generated by the coupling between the m = 3 mode and the main spiral structure confirm its density-wave nature. We observe also a signature of an m = 1 mode that is likely responsible for the lopsidedness of M51 at small and large radii. We provide a simple method to estimate the radial variation of the amplitude of the spiral perturbation (V sp) attributed to the different modes. The main spiral arm structure has 〈V sp〉 = 50-70 km s-1, while the streaming velocity associated with the m = 1 and m = 3 modes is, in general, two times lower. Our joint analysis of H I and CO velocity fields at low and high spatial resolution reveals that the atomic and molecular gas phases respond differently to the spiral perturbation due to their different vertical distribution and emission morphology. © 2014. The American Astronomical Society. All rights reserved.We thank our anonymous referee for thoughtful comments that improved the quality of the paper. We thank the IRAM staff for their support during the observations with the Plateau de Bure interferometer and the 30 m telescope. D.C. and A.H. acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG) via grant SCHI 536/5-1 and SCHI 536/7-1 as part of the priority program SPP 1573 “ISM-SPP: Physics of the Interstellar Medium.” C.L.D. acknowledges funding from the European Research Council for the FP7 ERC starting grant project LOCALSTAR. T.A.T. acknowledges support from NASA grant No. NNX10AD01G. During this work, J.P. was partially funded by the grant ANR-09-BLAN-0231-01 from the French Agence Nationale de la Recherche as part of the SCHISM project (http://schism.ens.fr/). E.S., A.H. and D.C. thank NRAO for their support and hospitality during their visits in Charlottesville. E.S. thanks the Aspen Center for Physics and the NSF grant No. 1066293 for hospitality during the development and writing of this paper. D.C. thanks Glenn van de Ven for the useful discussion and the help with the harmonic decomposition code. S.G.B. acknowledges economic support from Junta de Andalucia grant P08 TIC 03531. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc

The PdBI Arcsecond Whirlpool Survey (PAWS): Environmental dependence of giant molecular cloud properties in M51

This is the final version of the article. Available fromAmerican Astronomical Society / IOP Publishing via the DOI in this recordUsing data from the PdBI Arcsecond Whirlpool Survey (PAWS), we have generated the largest extragalactic giant molecular cloud (GMC) catalog to date, containing 1507 individual objects. GMCs in the inner M51 disk account for only 54% of the total 12CO(1-0) luminosity of the survey, but on average they exhibit physical properties similar to Galactic GMCs. We do not find a strong correlation between the GMC size and velocity dispersion, and a simple virial analysis suggests that ∼30% of GMCs in M51 are unbound. We have analyzed the GMC properties within seven dynamically motivated galactic environments, finding that GMCs in the spiral arms and in the central region are brighter and have higher velocity dispersions than inter-arm clouds. Globally, the GMC mass distribution does not follow a simple power-law shape. Instead, we find that the shape of the mass distribution varies with galactic environment: the distribution is steeper in inter-arm region than in the spiral arms, and exhibits a sharp truncation at high masses for the nuclear bar region. We propose that the observed environmental variations in the GMC properties and mass distributions are a consequence of the combined action of large-scale dynamical processes and feedback from high-mass star formation. We describe some challenges of using existing GMC identification techniques for decomposing the 12CO(1-0) emission in molecule-rich environments, such as M51's inner disk. © 2014. The American Astronomical Society. All rights reserved

Positive and negative evaluation of caregiving among three different types of informal care relationships

Based on the caregiver stress model, we examined how care demands, caregiver motivation, coping style and external support are associated with positive evaluation and caregiver burden among spousal, adult child and other types of care relations. Data from a sample of Dutch informal caregivers of 1,685 older persons (55 and older) were analyzed employing multivariate linear regression analyses for each of the care relationship types. Spouses (N = 206) report high positive evaluation and high burden, adult children (N = 1,093) report low positive evaluation, and other caregivers (N = 386) report high positive evaluation and a low burden. Multivariate linear regression analyses showed that motives and external support were important for positive evaluation but the impact varied among types of caregivers, whereas care demands and not asking for help were associated with burden for all types. Only among 'other' caregiver relationships, positive evaluation was negatively associated with burden. It is concluded that results confirm the dual nature of caregiving among spouses and children. The care context and motivation of the different types of caregivers explain their differences in care evaluation. Various interventions for types of caregivers are discussed. © 2013 Springer-Verlag Berlin Heidelberg

Lateral opening in the intact β-barrel assembly machinery captured by cryo-EM

The β-barrel assembly machinery (BAM) is a ~203 kDa complex of five proteins (BamA-E) which is essential for viability in E. coli. BAM promotes the folding and insertion of β-barrel proteins into the outer membrane via a poorly understood mechanism. Several current models suggest that BAM functions through a ‘lateral gating’ motion of the β-barrel of BamA. Here we present a cryo-EM structure of the BamABCDE complex, at 4.9 Å resolution. The structure is in a laterally open conformation showing that gating is independent of BamB binding. We describe conformational changes throughout the complex, and interactions between BamA, B, D, and E and the detergent micelle that suggest communication between BAM and the lipid bilayer. Finally, using an enhanced reconstitution protocol and functional assays, we show that for the outer membrane protein OmpT, efficient folding in vitro requires lateral gating in BAM