The chiral p-wave superconductor is the archetypal example of a state of matter that supports non-Abelian anyons, a highly desired type of exotic quasiparticle. With this, it is foundational for the ...distant goal of building a topological quantum computer. While some candidate materials for bulk chiral superconductors exist, they are subject of an ongoing debate about their actual paring state. Here we propose an alternative route to chiral superconductivity, consisting of the surface of an ordinary superconductor decorated with a two-dimensional lattice of magnetic impurities. We furthermore identify a promising experimental platform to realize this proposal.
Abstract
Geometrically frustrated kagome lattices are raising as novel platforms to engineer correlated topological electron flat bands that are prominent to electronic instabilities. Here, we ...demonstrate a phonon softening at the
k
z
=
π
plane in ScV
6
Sn
6
. The low energy longitudinal phonon collapses at ~98 K and
q
=
$$\frac{1}{3}\frac{1}{3}\frac{1}{2}$$
1
3
1
3
1
2
due to the electron-phonon interaction, without the emergence of long-range charge order which sets in at a different propagation vector
q
CDW
=
$$\frac{1}{3}\frac{1}{3}\frac{1}{3}$$
1
3
1
3
1
3
. Theoretical calculations corroborate the experimental finding to indicate that the leading instability is located at
$$\frac{1}{3}\frac{1}{3}\frac{1}{2}$$
1
3
1
3
1
2
of a rather flat mode. We relate the phonon renormalization to the orbital-resolved susceptibility of the trigonal Sn atoms and explain the approximately flat phonon dispersion. Our data report the first example of the collapse of a kagome bosonic mode and promote the 166 compounds of kagomes as primary candidates to explore correlated flat phonon-topological flat electron physics.
Context. From an astrometric point of view, quasars constitute quasi-ideal reference objects in the celestial sphere, with an a priori absence of proper motion. Since the second release of the Large ...Quasar Astrometric Catalog (LQAC), a large number of quasars have been discovered, in particular with the upcoming new release of the SDSS quasars catalog. Aims. Following the same procedure as in the two previous releases of the LQAC, our aim was to compile all the quasars recorded until the present date, with accurate recomputation of their equatorial coordinates in the ICRS and with the maximum of information concerning their physical properties, such as the redshift, the photometry, and the absolute magnitudes. Methods. For the purpose above, we carried out the cross-identification between the 9 catalogs of quasars chosen for their huge number of objects, including all the available data related to magnitudes, radiofluxes, and redshifts. This cross identification was particularly delicate because of a slight change in coordinates between the objects common to two successive releases of the SDSS and the elimination of some of them. Equatorial coordinates were recomputed more accurately according to the algorithms used for the elaboration of the Large Quasar Reference Frame (LQRF). Moreover, absolute magnitudes and morphological indexes of the new objects were given, following the same method as in the LQAC-2. Results. Our final catalog, called LQAC-3, contains 321 957 objects including a small proportion of AGNs (14 128) and BLLac (1183). This is roughly 70% more than the number of objects recorded in the LQAC-2. Conclusions. The LQAC-3 will be useful for the astronomical community since it gives the most complete information available about the whole set of already recorded quasars, with emphasis on the precision and accuracy of their coordinates with respect to the ICRF2.
We propose and develop a classical density functional theory for the description of a minor amount of water dissolved in ionic liquid in the vicinity of an electrode. In addition to the electrostatic ...energy and lattice-gas mixing entropy terms, the utilised grand canonical potential contains several phenomenological terms/parameters that describe short-range interactions between ions, water molecules and the electrode. Here we investigate: (i) specific interaction of ions and molecules with the electrode, which are responsible for their specific adsorption; (ii) hydrophilicity/hydrophobicity of ions. We obtain water electrosorption isotherms as a function of the potential drop across the electrical double layer, investigate its asymmetry with respect to the sign of electrode potential, and establish the relationship between the sign of this asymmetry and hydrophobicity/hydrophilicity of cations and anions. We also calculate the effect of water electrosorption on the double layer differential capacitance which brings clear new features to its voltage dependence, some of which have been already experimentally observed.
Do caregivers in non-Western communities adapt their behaviors to the needs of infants? This question reflects one of the most long-standing debates on the universality versus culture-specificity of ...caregiver-infant interactions in general and sensitive responsiveness to infants in particular. In this article, an integration of both points of view is presented, based on the theoretical origins of the sensitive responsiveness construct combined with the ethnographic literature on caregivers and infants in different parts of the world. This integration advocates universality without uniformity, and calls for multidisciplinary collaborations to investigate the complexities and nuances of caregiver-infant interactions in different cultures. Salient issues are illustrated with observations of infants (ages 7-31 months) in Mali, the Republic of Congo, and the Philippines.
There are scarce data regarding the prevalence, characteristics and outcomes of intracerebral hemorrhage (ICH) of undetermined (unknown or cryptogenic) etiology. We sought to determine the ...prevalence, radiological characteristics, and clinical outcomes of undetermined ICH.
Systematic review and meta-analysis of studies involving patients with spontaneous ICH was conducted to primarily assess the prevalence and clinical-radiological characteristics of undetermined ICH. Additionally, we assessed the rates for ICH secondary to hypertensive arteriopathy and cerebral amyloid angiopathy. Subgroup analyses were performed based on the use of (1) etiology-oriented ICH classification, (2) detailed neuroimaging, and (3) Boston criteria among patients with cerebral amyloid angiopathy related ICH. We pooled the prevalence rates using random-effects models, and assessed the heterogeneity using Cochran Q and I2 statistics.
We identified 24 studies comprising 15 828 spontaneous ICH patients (mean age, 64.8 years; men, 60.8%). The pooled prevalences of hypertensive arteriopathy ICH, undetermined ICH, and cerebral amyloid angiopathy ICH were 50% (95% CI, 43%–58%), 18% (95% CI, 13%–23%), and 12% (95% CI, 7%–17% P<0.001 between subgroups). The volume of ICH was the largest in cerebral amyloid angiopathy ICH (24.7 95% CI, 19.7–29.8 mL), followed by hypertensive arteriopathy ICH (16.2 95% CI, 10.9–21.5 mL) and undetermined ICH (15.4 95% CI, 6.2–24.5 mL). Among patients with undetermined ICH, the rates of short-term mortality (within 3 months) and concomitant intraventricular hemorrhage were 33% (95% CI, 25%–42%) and 38% (95% CI, 28%–48%), respectively. Subgroup analysis demonstrated a higher rate of undetermined ICH among studies that did not use an etiology-oriented classification (22% 95% CI, 15%–29%). No difference was observed between studies based on the completion of detailed neuroimaging to assess the rates of undetermined ICH (P=0.62).
The etiology of spontaneous ICH remains unknown or cryptogenic among 1 in 7 patients in studies using etiology-oriented classification and among 1 in 4 patients in studies that avoid using etiology-oriented classification. The short-term mortality in undetermined ICH is high despite the relatively small ICH volume.
We report the discovery of 76 new T dwarfs from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Near-infrared broad- and narrow-band photometry and spectroscopy are presented for ...the new objects, along with Wide-field Infrared Survey Explorer (WISE) and warm-Spitzer photometry. Proper motions for 128 UKIDSS T dwarfs are presented from a new two epoch LAS proper motion catalogue. We use these motions to identify two new benchmark systems: LHS 6176AB, a T8p+M4 pair and HD 118865AB, a T5.5+F8 pair. Using age constraints from the primaries and evolutionary models to constrain the radii, we have estimated their physical properties from their bolometric luminosity. We compare the colours and properties of known benchmark T dwarfs to the latest model atmospheres and draw two principal conclusions. First, it appears that the H − 4.5 and J − W2 colours are more sensitive to metallicity than has previously been recognized, such that differences in metallicity may dominate over differences in T
eff when considering relative properties of cool objects using these colours. Secondly, the previously noted apparent dominance of young objects in the late-T dwarf sample is no longer apparent when using the new model grids and the expanded sample of late-T dwarfs and benchmarks. This is supported by the apparently similar distribution of late-T dwarfs and earlier type T dwarfs on reduced proper motion diagrams that we present. Finally, we present updated space densities for the late-T dwarfs, and compare our values to simulation predictions and those from WISE.
Context. From an astrometric point of view, quasars constitute the best and almost ideal reference objects in the celestial sphere, with a priori no significant proper motion. Since the third release ...of the Large Quasar Astrometric Catalogue (LQAC-3), a large number of quasars have been discovered, in particular those coming from the DR12Q release of the SDSS. Moreover, for cross-matched objects, we have taken advantage of the very accurate determinations of the quasars identified within the recent Gaia DR1 catalogue. Aims. Following the same procedure as in the three previous releases of the LQAC, our aim is to compile the large majority of all the quasars recorded so far. Our goal is to record their best coordinates and substantial information concerning their physical properties such as the redshift as well as multi-bands apparent and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR1 catalogue. Methods. New quasars coming from the DR12Q release were cross-matched with the precedent LQAC-3 compilation with a 1′′ search radius, in order to add the objects without counterpart to the LQAC-4 compilation. A similar cross-match was done with Gaia DR1 to identify the known quasars detected by Gaia. This enables one to improve significantly the positioning of these objects, and in parallel to study the astrometric performance of the individual catalogues of the LQAC-4 compilation. Finally, a new method was used to determine absolute magnitudes. Results. Our final catalogue, called LQAC-4, contains 443 725 objects. This is roughly 37.82% more than the number of objects recorded in the LQAC-3. Among them, 249 071 were found in common with the Gaia DR1, with a 1′′ search radius. That corresponds to 56.13% of the whole population in the compilation. Conclusions. The LQAC-4 delivers to the astronomical community a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of compact AGNs), with the aim of giving their best equatorial coordinates with respect to the ICRF2 and with exhaustive additional information. For more than 50% of the sample, these coordinates come from the very recent Gaia DR1.
Microbial amplicon sequencing studies are an important tool in biological and biomedical research. Widespread 16S rRNA gene microbial surveys have shed light on the structure of many ecosystems ...inhabited by bacteria, including the human body. However, specialized software and algorithms are needed to convert raw sequencing data into biologically meaningful information (i.e. tables of bacterial counts). While different bioinformatic pipelines are available in a rapidly changing and improving field, users are often unaware of limitations and biases associated with individual pipelines and there is a lack of agreement regarding best practices. Here, we compared six bioinformatic pipelines for the analysis of amplicon sequence data: three OTU-level flows (QIIME-uclust, MOTHUR, and USEARCH-UPARSE) and three ASV-level (DADA2, Qiime2-Deblur, and USEARCH-UNOISE3). We tested workflows with different quality control options, clustering algorithms, and cutoff parameters on a mock community as well as on a large (N = 2170) recently published fecal sample dataset from the multi-ethnic HELIUS study. We assessed the sensitivity, specificity, and degree of consensus of the different outputs. DADA2 offered the best sensitivity, at the expense of decreased specificity compared to USEARCH-UNOISE3 and Qiime2-Deblur. USEARCH-UNOISE3 showed the best balance between resolution and specificity. OTU-level USEARCH-UPARSE and MOTHUR performed well, but with lower specificity than ASV-level pipelines. QIIME-uclust produced large number of spurious OTUs as well as inflated alpha-diversity measures and should be avoided in future studies. This study provides guidance for researchers using amplicon sequencing to gain biological insights.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
49 new T dwarfs identified using methane imaging Cardoso, C. V.; Burningham, B.; Smart, R. L. ...
Monthly Notices of the Royal Astronomical Society,
07/2015, Letnik:
450, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We present the discovery of 49 new photometrically classified T dwarfs from the combination of large infrared and optical surveys combined with follow-up Telescopio Nazionale Galileo photometry. We ...used multiband infrared and optical photometry from the United Kingdom Infrared Telescope and Sloan Digital Sky Surveys to identify possible brown dwarf candidates, which were then confirmed using methane filter photometry. We have defined a new photometric conversion between CH4s − CH4l colour and spectral type for T4–T8 brown dwarfs based on a part of the sample that has been followed up using methane photometry and spectroscopy. Using methane differential photometry as a proxy for spectral type for T dwarfs has proved to be a very efficient technique. Of a subset of 45 methane selected brown dwarfs that were observed spectroscopically, 100 per cent were confirmed as T dwarfs. Future deep imaging surveys will produce large samples of faint brown dwarf candidates, for which spectroscopy will not be feasible. When broad wavelength coverage is unavailable, methane imaging offers a means to efficiently classify candidates from such surveys using just a pair of near-infrared images.
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