Origin of superconductivity and latent charge density wave in NbS2_2

We elucidate the origin of the phonon-mediated superconductivity in 2$H$-NbS$_2$ using the ab initio anisotropic Migdal-Eliashberg theory including Coulomb interactions. We demonstrate that superconductivity is associated with Fermi surface hot spots exhibiting an unusually strong electron-phonon interaction. The electron-lattice coupling is dominated by low-energy anharmonic phonons, which place the system on the verge of a charge density wave instability. We also provide definitive evidence for two-gap superconductivity in 2$H$-NbS$_2$, and show that the low- and high-energy peaks observed in tunneling spectra correspond to the $\Gamma$- and $K$-centered Fermi surface pockets, respectively. The present findings call for further efforts to determine whether our proposed mechanism underpins superconductivity in the whole family of metallic transition metal dichalcogenides.Comment: 6 pages, 5 figures and Supplemental Materia

Video genre categorization and representation using audio-visual information

International audienceWe propose an audio-visual approach to video genre classification using content descriptors that exploit audio, color, temporal, and contour information. Audio information is extracted at block-level, which has the advantage of capturing local temporal information. At the temporal structure level, we consider action content in relation to human perception. Color perception is quantified using statistics of color distribution, elementary hues, color properties, and relationships between colors. Further, we compute statistics of contour geometry and relationships. The main contribution of our work lies in harnessingn the descriptive power of the combination of these descriptors in genre classification. Validation was carried out on over 91 h of video footage encompassing 7 common video genres, yielding average precision and recall ratios of 87% to 100% and 77% to 100%, respectively, and an overall average correct classification of up to 97%. Also, experimental comparison as part of the MediaEval 2011 benchmarkingn campaign demonstrated the efficiency of the proposed audiovisual descriptors over other existing approaches. Finally, we discuss a 3-D video browsing platform that displays movies using efaturebased coordinates and thus regroups them according to genre

Psychoanalytic and psychodynamic therapies for depression. The evidence base.

David Taylor, a consultant psychotherapist at the Tavistock & Portman NHS Foundation Trust (120 Belsize Lane, London NW3 5BA, UK. Email: [email protected]), is the clinical lead of the Tavistock Adult Depression Study (a randomised controlled trial of 60 sessions of weekly psychoanalytic psychotherapy v. treatment as usual for patients with chronic, refractory depression). He is a training and supervising psychoanalyst at the Institute of Psychoanalysis. This article argues that the current approach to guideline development for the treatment of depression is not supported by the evidence: clearly depression is not a disease for which treatment efficacy is best determined by short-term randomised controlled trials. As a result, important findings have been marginalised. Different principles of evidence-gathering are described. When a wider range of the available evidence is critically considered the case for dynamic approaches to the treatment of depression can be seen to be stronger than is often thought. Broadly, the benefits of short-term psychodynamic therapies are equivalent in size to the effects of antidepressants and cognitive–behavioural therapy (CBT). The benefits of CBT may occur more quickly, but those of short-term psychodynamic therapies may continue to increase after treatment. There may be a ceiling on the effects of short-term treatments of whatever type. Longer-term psychodynamic treatments may improve associated social, work and personal dysfunctions as well as reductions in depressive symptoms

Computational and spectroscopic studies of organic mixed-valence compounds: where is the charge?

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.This article discusses recent progress by a combination of spectroscopy and quantum-chemical calculations in classifying and characterizing organic mixed-valence systems in terms of their localized vs.delocalized character. A recently developed quantum-chemical protocol based on non-standard hybrid functionals and continuum solvent models is evaluated for an extended set of mixed-valence bis-triarylamine radical cations, augmented by unsymmetrical neutral triarylamine-perchlorotriphenylmethyl radicals. It turns out that the protocol is able to provide a successful assignment to class II or class III Robin-Day behavior and gives quite accurate ground- and excited-state properties for the radical cations. The limits of the protocol are probed by the anthracene-bridged system8, where it is suspected that specific solute–solvent interactions are important and not covered by the continuum solvent model. Intervalence charge-transfer excitation energies for the neutral unsymmetrical radicals are systematically overestimated, but dipole moments and a number of other properties are obtained accurately by the protocol.DFG, GRK 1221, Steuerung elektronischer Eigenschaften von Aggregaten pi-konjugierter Molekül

Buried alive: Aquatic plants survive in ‘ghost ponds’ under agricultural fields

The widespread loss of wetlands due to agricultural intensification has been highlighted as a major threat to aquatic biodiversity. However, all is not lost as we reveal that the propagules of some aquatic species could survive burial under agricultural fields in the sediments of ‘ghost ponds’ - ponds in-filled during agricultural land consolidation. Our experiments showed at least eight aquatic macrophyte species to germinate from seeds and oospores, following 50–150 years of dormancy in the sediments of ghost ponds. This represents a significant proportion of the expected macrophyte diversity for local farmland ponds, which typically support between 6 and 14 macrophyte species. The rapid (< 6 months) re-colonisation of resurrected ghost ponds by a diverse aquatic vegetation similarly suggests a strong seed-bank influence. Ghost ponds represent abundant, dormant time capsules for aquatic species in agricultural landscapes around the globe, affording opportunities for enhancing landscape-scale aquatic biodiversity and connectivity. While reports of biodiversity loss through agricultural intensification dominate conservation narratives, our study offers a rare positive message, demonstrating that aquatic organisms survive prolonged burial under intensively managed agricultural fields. We urge conservationists and policy makers to consider utilizing and restoring these valuable resources in biodiversity conservation schemes and in agri-environmental approaches and policies

Expertise in performance assessment: assessors' perspectives

The recent rise of interest among the medical education community in individual faculty making subjective judgments about medical trainee performance appears to be directly related to the introduction of notions of integrated competency-based education and assessment for learning. Although it is known that assessor expertise plays an important role in performance assessment, the roles played by different factors remain to be unraveled. We therefore conducted an exploratory study with the aim of building a preliminary model to gain a better understanding of assessor expertise. Using a grounded theory approach, we conducted seventeen semi-structured interviews with individual faculty members who differed in professional background and assessment experience. The interviews focused on participants' perceptions of how they arrived at judgments about student performance. The analysis resulted in three categories and three recurring themes within these categories: the categories assessor characteristics, assessors' perceptions of the assessment tasks, and the assessment context, and the themes perceived challenges, coping strategies, and personal development. Central to understanding the key processes in performance assessment appear to be the dynamic interrelatedness of the different factors and the developmental nature of the processes. The results are supported by literature from the field of expertise development and in line with findings from social cognition research. The conceptual framework has implications for faculty development and the design of programs of assessmen

Heterotic AdS_3/CFT_2 duality with (0,4) spacetime supersymmetry

We discuss the AdS_3/CFT_2 duality of a heterotic three-charge model with (0,4) target space supersymmetry. The worldsheet theory for heterotic strings on the AdS_3 x S^3/Z_N x T^4 near-horizon geometry was constructed by Kutasov, Larsen and Leigh in [hep-th/9812027]. We propose that the dual conformal field theory is given by a two-dimensional (0,4) sigma model arising on the Higgs branch of an orbifolded ADHM model. As a non-trivial consistency check of the correspondence, we find that the left- and right-moving central charges of the infrared conformal field theory agree with those predicted by the worldsheet model. Moreover, using the entropy function formalism, we show that to next-to-leading order the central charge can also be obtained from an alpha'-corrected supergravity theory.Comment: 34 pages, 2 figures, references added, to be published in Nucl. Phys.

Fractography of poly(: N -isopropylacrylamide) hydrogel networks crosslinked with mechanofluorophores using confocal laser scanning microscopy

Due to their soft and brittle nature, the mechanical characterization of polymer hydrogels is a difficult task employing traditional testing equipment. Here, we endowed poly(N-isopropyl acrylamide) (PNIPAAm) hydrogel networks with Diels-Alder adducts of π-extended anthracenes as mechanofluorophore crosslinkers. After swelling the networks with varying amounts of water and subjecting them to force, we visualized the subsequent fluorescence caused by covalent bond scission with confocal laser scanning microscopy (CLSM) and related the intensities to the macroscopic fracture mechanics and the elastic moduli recorded with traditional uniaxial compression. The sensitivity of the mechanofluorophores allowed the analysis of low levels of mechanical stress produced via a hand-induced needle-puncturing process and, thus, is an alternative to conventional force application methods. The detection and precise localization of covalent bond scission via CLSM helps elucidating the interrelationship between molecular structure and the macroscopic properties of chemically crosslinked polymeric hydrogels. We believe that this micro-scale mechanophore-assisted fractography can establish a new paradigm for the mechanical analysis of soft matter in fields covering traditional polymer and life sciences. © 2019 The Royal Society of Chemistry

Sensitivity of arctic surface temperatures to sea ice thickness changes using the regional climate model mar

Since the beginning of this century, the Arctic Ocean has experienced a rapid decrease in sea ice extent, which strongly contributes to a pronounced regional climate warming known as “Arctic Amplification”, i.e. two times as large as the global average. Sea ice concentration (SIC) and sea ice thickness (SIT) mainly control changes in Arctic Ocean surface temperatures by insulating the warmer ocean water from the colder air above. Changes in atmospheric temperatures could perturb the Arctic climate, by affecting the regional atmospheric circulation. In most regional climate models (RCMs), SIC is prescribed from climate reanalyses whereas SIT is fixed in space and time, despite observations of large seasonal variations. Here, we compare climate simulations from the regional climate model MAR forced by the ERA-Interim and OSTIA reanalyses, using fixed SIT, to MAR simulations where SIT and SIC are prescribed by the GLORYS2V4 data set. The set of simulations covers the Arctic-CORDEX domain spanning the whole Arctic Ocean at a spatial resolution of 50 km for the period 2000-2015. This study aims to (1) improve the representation of surface temperatures, wind speed and direction within the Arctic boundary layer simulated by MAR, and to (2) estimate the sensitivity of Arctic surface temperatures and atmospheric circulation to prescribed SIT in MAR. Although our findings highlight the local sensitivity of surface temperatures to SIT changes, they also reveal that there is no clear benefit of using space and time varying SIT data sets to force MAR at 50 km resolution.Depuis le début de ce siècle, l’Océan Arctique a connu une diminution rapide de son étendue de glace de mer, entrainant un réchauffement climatique régional appelé "Amplification Arctique", i.e. deux fois plus marqué que le réchauffement global. En jouant le rôle d’isolant entre l’océan (plus chaud) et l’atmosphère, l’épaisseur et la concentration de glace de mer contrôlent la température à la surface de l’Océan Arctique. Une modification de la température de surface pourrait entrainer une perturbation du système climatique, par le biais de son influence sur la circulation atmosphérique régionale. Dans la plupart des modèles climatiques régionaux (RCMs), la concentration de glace de mer est prescrite par des réanalyses, tandis que l’épaisseur de glace de mer est fixe dans le temps et l’espace, malgré sa variation saisonnière importante. Dans cette étude, on comparera des simulations du MAR forcé par ERA-intérim et OSTIA, i.e utilisant une épaisseur de glace de mer fixe, avec des simulations ou l’épaisseur et la concentration de glace de mer sont prescrites par GLORYS2v4. L’ensemble des simulations concerne le domaine CORDEX-Arctique et couvre la période 2000-2015. L’objectif de ce travail est (i) d’améliorer la représentation de la température de surface, de la vitesse et direction du vent dans la couche limite atmosphérique du MAR en Arctique et; (ii) d’estimer la sensibilité de la température de surface et de la circulation atmosphérique à différentes épaisseurs de glace de mer prescrites dans le MAR. Bien que nous démontrions la sensibilité locale de la température de surface à un changement d’épaisseur de glace de mer (fixe), nous montrons aussi qu’il n’y a pas de bénéfice clair quant à l’utilisation de l’épaisseur de glace de mer variable dans le temps et l’espace comme forçage à la surface du MAR à 50 km de résolution

MaskAl: Privacy Preserving Masked Reads Alignment using Intel SGX

The recent introduction of new DNA sequencing techniques caused the amount of processed and stored biological data to skyrocket. In order to process these vast amounts of data, bio-centers have been tempted to use low-cost public clouds. However, genomes are privacy sensitive, since they store personal information about their donors, such as their identity, disease risks, heredity and ethnic origin. The first critical DNA processing step that can be executed in a cloud, i.e., read alignment, consists in finding the location of the DNA sequences produced by a sequencing machine in the human genome. While recent developments aim at increasing performance, only few approaches address the need for fast and privacy preserving read alignment methods. This paper introduces MaskAl, a novel approach for read alignment. MaskAl combines a fast preprocessing step on raw genomic data — filtering and masking — with established algorithms to align sanitized reads, from which sensitive parts have been masked out, and refines the alignment score using the masked out information with Intel’s software guard extensions (SGX). MaskAl is a highly competitive privacy-preserving read alignment software that can be massively parallelized with public clouds and emerging enclave clouds. Finally, MaskAl is nearly as accurate as plain-text approaches (more than 96% of aligned reads with MaskAl compared to 98% with BWA) and can process alignment workloads 87% faster than current privacy-preserving approaches while using less memory and network bandwidth