Spatially resolving the atmosphere of the non-Mira-type AGB star SW Vir in near-infrared molecular and atomic lines with VLTI/AMBER

We present a near-infrared spectro-interferometric observation of the non-Mira-type, semiregular asymptotic giant branch star SW Vir. Our aim is to probe the physical properties of the outer atmosphere with spatially resolved data in individual molecular and atomic lines. We observed SW Vir in the spectral window between 2.28 and 2.31 micron with the near-infrared interferometric instrument AMBER at ESO's Very Large Telescope Interferometer (VLTI). Thanks to AMBER's high spatial resolution and high spectral resolution of 12000, the atmosphere of SW Vir has been spatially resolved not only in strong CO first overtone lines but also in weak molecular and atomic lines of H2O, CN, HF, Ti, Fe, Mg, and Ca. Comparison with the MARCS photospheric models reveals that the star appears larger than predicted by the hydrostatic models not only in the CO lines but also even in the weak molecular and atomic lines. We found that this is primarily due to the H2O lines (but also possibly due to the HF and Ti lines) originating in the extended outer atmosphere. Although the H2O lines manifest themselves very little in the spatially unresolved spectrum, the individual rovibrational H2O lines from the outer atmosphere can be identified in the spectro-interferometric data. Our modeling suggests an H2O column density of 10^{19}--10^{20} cm^{-2} in the outer atmosphere extending out to ~2 Rstar. Our study has revealed that the effects of the nonphotospheric outer atmosphere are present in the spectro-interferometric data not only in the strong CO first overtone lines but also in the weak molecular and atomic lines. Therefore, analyses of spatially unresolved spectra, such as for example analyses of the chemical composition, should be carried out with care even if the lines appear to be weak.Comment: 8 pages, 6 figures, accepted for publication in Astronomy and Astrophysic

Parallel Program Archetypes

A parallel program archetype is an abstraction that captures the common features of a class of problems with similar computational structure and combines them with a parallelization strategy to produce a pattern of dataflow and communication. Such abstractions are useful in application development, both as a conceptual framework and as a basis for tools and techniques. This paper describes an approach to parallel application development based on archetypes and presents two example archetypes with applications

Assessment of Liquefaction-Induced Foundation Soil Deformations

Although there exist some consensus regarding seismic soil liquefaction triggering assessment of free field soil sites, estimating the liquefaction triggering potential beneath building foundations still stays as a controversial and a difficult issue. Assessing liquefaction triggering potential under building foundations requires the estimation of cyclic and static stress state of the soil medium. In the recent studies (e.g. Unutmaz 2008), the cyclic stress ratio corrected for Kα and Kσ effects under and adjacent to building foundations subjected to cyclic loading are to be estimated with the help of a series of 2-D and 3-D numerical simulations for different generic cases. A representative and a maximum cyclic stress ratio terms of the soil-structure-earthquake interaction system, denoted as CSRSSEI,rep and CSRSSEI,max respectively was defined as a function of i) ratio of the pre-earthquake fundamental period of the structure and soil (σ), ii) free field spectral acceleration at the fixed-base period of the structure(SA), iii) the peak ground acceleration of the free field soil sites (PGA), and iv) aspect ratio of the structure (h/B). In this paper, the results of the previously mentioned numerical findings have been verified by using case histories documented after 1999 Kocaeli Earthquake, where significant foundation displacements were observed due to liquefaction of the underlying foundation soils. The foundation soil profiles of these case histories generally consist of silty soils, sand-silt mixtures and silt-clay mixtures. Overburden and procedure corrected SPT-N values vary in the range of 2 to 5 blows/30 cm in the upper 5 meters and gradually increases up to a maximum value of 25 blows/30 cm beyond depths of 5 to 8 m’s. Overlying structures are mainly 3 to 4 storey, residential buildings with no basements. As the concluding remark, the proposed simplified procedures are shown to predict cyclically-induced foundation settlements accurately within an accuracy factor of two (i.e.: predictions fall within 1:2 and 2:1 limits of the measured settlements)

Extended skyrmion lattice scattering and long-time memory in the chiral magnet Fe1−x_{1-x}Cox_xSi

Small angle neutron scattering measurements on a bulk single crystal of the doped chiral magnet Fe$_{1-x}$Co$_x$Si with $x$=0.3 reveal a pronounced effect of the magnetic history and cooling rates on the magnetic phase diagram. The extracted phase diagrams are qualitatively different for zero and field cooling and reveal a metastable skyrmion lattice phase outside the A-phase for the latter case. These thermodynamically metastable skyrmion lattice correlations coexist with the conical phase and can be enhanced by increasing the cooling rate. They appear in a wide region of the phase diagram at temperatures below the $A$-phase but also at fields considerably smaller or higher than the fields required to stabilize the A-phase

Integrating Task and Data Parallelism with the Collective Communication Archetype

A parallel program archetype aids in the development of reliable, efficient parallel applications with common computation/communication structures by providing stepwise refinement methods and code libraries specific to the structure. The methods and libraries help in transforming a sequential program into a parallel program via a sequence of refinement steps that help maintain correctness while refining the program to obtain the appropriate level of granularity for a target machine. The specific archetype discussed here deals with the integration of task and data parallelism by using collective (or group) communication. This archetype has been used to develop several applications

The long egress of GJ~436b's giant exosphere

The M dwarf GJ 436 hosts a transiting warm Neptune known to experience atmospheric escape. Previous observations revealed the presence of a giant hydrogen exosphere transiting the star for more than 5 h, and absorbing up to 56% of the flux in the blue wing of the stellar Lyman-{\alpha} line of neutral hydrogen (H i Ly{\alpha}). The unexpected size of this comet-like exosphere prevented observing the full transit of its tail. In this Letter, we present new Ly{\alpha} observations of GJ 436 obtained with the Space Telescope Imaging Spectrograph (STIS) instrument onboard the Hubble Space Telescope. The stability of the Ly{\alpha} line over six years allowed us to combine these new observations with archival data sets, substantially expanding the coverage of the exospheric transit. Hydrogen atoms in the tail of the exospheric cloud keep occulting the star for 10-25 h after the transit of the planet, remarkably confirming a previous prediction based on 3D numerical simulations with the EVaporating Exoplanet code (EVE). This result strengthens the interpretation that the exosphere of GJ 436b is shaped by both radiative braking and charge exchanges with the stellar wind. We further report flux decreases of 15 +/- 2% and 47 +/- 10% in the red wing of the Ly{\alpha} line and in the line of ionised silicon (Si iii). Despite some temporal variability possibly linked with stellar activity, these two signals occur during the exospheric transit and could be of planetary origin. Follow-up observations will be required to assess the possibility that the redshifted Ly{\alpha} and Si iii absorption signatures arise from interactions between the exospheric flow and the magnetic field of the star.Comment: 10 pages, 7 figures, published in A&

Universality of the helimagnetic transition in cubic chiral magnets: Small angle neutron scattering and neutron spin echo spectroscopy studies of Fe1−x_{1-x}Cox_xSi

We present a comprehensive Small Angle Neutron Scattering (SANS) and Neutron Spin Echo Spectroscopy (NSE) study of the structural and dynamical aspects of the helimagnetic transition in Fe$_{1-x}$Co$_x$Si with $x$ = 0.30. In contrast to the sharp transition observed in the archetype chiral magnet MnSi, the transition in Fe$_{1-x}$Co$_x$Si is gradual and long-range helimagnetic ordering coexists with short-range correlations over a wide temperature range. The dynamics are more complex than in MnSi and involve long relaxation times with a stretched exponential relaxation which persists even under magnetic field. These results in conjunction with an analysis of the hierarchy of the relevant length scales show that the helimagnetic transition in Fe$_{1-x}$Co$_x$Si differs substantially from the transition in MnSi and question the validity of a universal approach to the helimagnetic transition in chiral magnets

The effect of opioid therapy on sleep quality in patients with chronic non-malignant pain : a systematic review and exploratory meta-analysis

Current guidelines recommend opioid therapy to chronic non-malignant pain (CNP) patients when the benefits for pain and function outweigh risks. This systematic review examined the effects of opioid therapy on sleep – a valued functional outcome– in CNP. Electronic and hand searches of relevant studies up through July 2017 identified 18 eligible studies providing data from 3,746 CNP patients for analysis. Twelve of these studies were randomised controlled trials (RCTs) of up to 12-month in duration. Low-medium dosed oxycodone and transdermal fentanyl were the most tested therapies (n=4 each). Only two studies used objective sleep measure in addition to self-report ratings, questionnaires or sleep diary. Whilst calmer sleep with less body/leg movements and fewer awakenings could be achieved following opioid therapy, these might occur with increased sleep-disordered breathing and a much-shortened rapid eye movement (REM) sleep latency. Both the narrative synthesis and exploratory meta-analysis suggest that opioid therapy in CNP is associated with improved self-reported sleep quality. However, the effect is inconsistent, small (Standardised Mean Difference = 0.36), and may be accompanied by excessive daytime sleepiness. As a Cochrane-recommended assessment revealed “unclear” or “high” overall risk of bias for all studies, future opioid trials of stronger methodology and better reporting are needed to confirm and elucidate the effect