Out-of-plane fluctuation conductivity of layered superconductors in strong electric fields

The non-Ohmic effect of a high electric field on the out-of-plane magneto-conductivity of a layered superconductor near the superconducting transition is studied in the frame of the Langevin approach to the time-dependent Ginzburg-Landau equation. The transverse fluctuation conductivity is computed in the self-consistent Hartree approximation for an arbitrarily strong electric field and a magnetic field perpendicular to the layers. Our results indicate that high electric fields can be effectively used to suppress the out-of-plane fluctuation conductivity in high-temperature superconductors and a significant broadening of the transition induced by a strong electric field is predicted. Extensions of the results are provided for the case when the electric field is applied at an arbitrary angle with respect to the layers, as well as for the three-dimensional anisotropic regime of a strong interlayer coupling.Comment: to be published in Phys. Rev.

Debris Disks in NGC 2547

We have surveyed the 30 Myr-old cluster NGC 2547 for planetary debris disks using Spitzer. At 4.5-8 um we are sensitive to the photospheric level down to mid-M stars (0.2 Msol) and at 24 um to early-G stars (1.2 Msol). We find only two to four stars with excesses at 8 um out of ~400-500 cluster members, resulting in an excess fraction <~1 percent at this wavelength. By contrast, the excess fraction at 24 um is ~40 percent (for B-F types). Out of four late-type stars with excesses at 8 um two marginal ones are consistent with asteroid-like debris disks. Among stars with strong 8 um excesses one is possibly from a transitional disk, while another one can be a result of a catastrophic collision. Our survey demonstrates that the inner 0.1-1 AU parts of disks around solar-type stars clear out very thoroughly by 30 Myrs of age. Comparing with the much slower decay of excesses at 24 and 70 um, disks clear from the inside out, of order 10 Myr for the inner zones probed at 8 um compared with a hundred or more Myr for those probed with the two longer wavelengths.Comment: Accepted to ApJ, 29 pages, 13 figs. A Note in Proof concerning cluster's age was added in the original submission of 2007 July 19. Full Tables 1 and 2 in the electronic form together with the article with full resolution figures are available at http://www.astro.ufl.edu/~ngorlova/disksNGC2547

The very nearby M/T dwarf binary SCR 1845-6357

The recently discovered star SCR 1845-6357 is the first late M/T dwarf binary discovered. SCR 1845 is a particular object due to its tight orbit (currently around 4 AU) and its proximity to the Sun (3.85 pc). We present spatially resolved VLT/NACO images and low resolution spectra of SCR 1845 in the J, H and K near-infrared bands. Since the T dwarf companion, SCR 1845B, is so close to the primary SCR 1845A, orbital motion is evident even within a year. Following the orbital motion, the binary's mass can be measured accurately within a decade, making SCR 1845B a key T-dwarf mass-luminosity calibrator. The NIR spectra allow for accurate determination of spectral type and also for rough estimates of the object's physical parameters. The spectral type of SCR 1845B is determined by direct comparison of the flux calibrated JHK spectra with T dwarf standard template spectra and also by NIR spectral indices obtained from synthetic photometry. Constrained values for surface gravity, effective temperature and metallicity are derived by comparison with model spectra. Our data prove that SCR 1845B is a brown dwarf of spectral type T6 that is co-moving with and therefore gravitationally bound to the M8.5 primary. Fitting the NIR spectrum of SCR 1845B to model spectra yields an effective temperature of about 950K and a surface gravity log(g)=5.1 (cgs) assuming solar metallicity. Mass and age of SCR 1845B are in the range 40 to 50 Jupiter masses and 1.8 to 3.1 Gyr.Comment: 5 pages, 4 figures, accepted for publication in Astronomy & Astrophysic

The use of classical and modern methods in rapeseed (Brassica napus) breeding at VNIIMK

Introduction. Rapeseed is a facultative autogamous plant; its percentage of cross-pollination is 10–50%, so rapeseed breeding engages the line and population breeding methods as well as the development of hybrids and all innovative research approaches.Material and methods. Among the main techniques used for the development of parent material and, eventually, cultivars at the Pustovoit Institute (VNIIMK) is the pedigree method (individual selection from intraspecific and interspecific hybrid populations, combined with inbreeding). Physical and chemical mutagenesis is also employed in rapeseed breeding at VNIIMK. The material with yellow-colored seed coat has been obtained by exposing rapeseed seeds to various doses of gamma rays (50, 100 and 150 kR). Seed treatment with chemical mutagens is primarily aimed at changing the fatty acid composition of oil.Results. Breeding achievements for winter and spring rapeseed, registered by VNIIMK in the State Register of Breeding Achievements of the Russian Federation over the past 15 years, are highly productive line cultivars with a seed yield of 4–5 t/ha for winter rapeseed, and 2–3 t/ha for spring rapeseed. Promising experimental interline hybrids, significantly exceeding the reference in seed yield (by 1.61–2.26 t/ha), have been developed. Yellowseeded lines, which exceed the black-seeded reference cv. ‘Tavrion’ in seed yield by 0.08–0.15 t/ha, have been selected. We developed the material with an oleic acid level of 78.9–80.5%

Breeding of winter rapeseed inbred lines for the development of parent forms for hybrids

Introduction. The V.S. Pustovoit All-Russian Research Institute of Oil Crops (VNIIMK) performs the breeding of interline rapeseed hybrids using the Ogura CMS. The program of interline winter rapeseed hybrid development was aimed at studying the efficiency of self-pollinated line breeding from population cultivars, assessing the impact of inbreeding depression on economically important traits, analyzing the changes in the lines’ traits after their transition to the sterile basis, and obtaining fertility restorer lines with an acceptable level of glucosinolate content in seeds.Materials and methods. Intraspecific hybrids, cultivars developed at the Pustovoit Institute and those of foreign breeding were employed as parent material for the development of self-pollinated lines. Self-pollination of rapeseed plants was performed using spunbond isolators. Over 1000 plants were self-pollinated every year. Generations of self-pollinated lines S1 –S4 were planted on 2.25 m2 plots, and during the growth season their visual screening was undertaken to assess their morphobiological traits. Starting with S5, the lines were evaluated for their yield on 7.5 m2 plots.Results. The inbreeding depression was found to not exceed 3–15% of the seed yield. The transition of the lines to sterile cytoplasm did not have any negative consequences. A series of experimental hybrids were developed, exceeding the reference cultivar ‘Loris’ in seed yield by 23–48%. New hybrid combinations also exceeded the reference in seed yield by 21–54%

The low level of debris disk activity at the time of the Late Heavy Bombardment: a Spitzer study of Praesepe

We present 24 micron photometry of the intermediate-age open cluster Praesepe. We assemble a catalog of 193 probable cluster members that are detected in optical databases, the Two Micron All Sky Survey (2MASS), and at 24 micron, within an area of ~ 2.47 square degrees. Mid-IR excesses indicating debris disks are found for one early-type and for three solar-type stars. Corrections for sampling statistics yield a 24 micron excess fraction (debris disk fraction) of 6.5 +- 4.1% for luminous and 1.9 +- 1.2% for solar-type stars. The incidence of excesses is in agreement with the decay trend of debris disks as a function of age observed for other cluster and field stars. The values also agree with those for older stars, indicating that debris generation in the zones that emit at 24 micron falls to the older 1-10 Gyr field star sample value by roughly 750 Myr. We discuss our results in the context of previous observations of excess fractions for early- and solar-type stars. We show that solar-type stars lose their debris disk 24 micron excesses on a shorter timescale than early-type stars. Simplistic Monte Carlo models suggest that, during the first Gyr of their evolution, up to 15-30% of solar-type stars might undergo an orbital realignment of giant planets such as the one thought to have led to the Late Heavy Bombardment, if the length of the bombardment episode is similar to the one thought to have happened in our Solar System. In the Appendix, we determine the cluster's parameters via boostrap Monte Carlo isochrone fitting, yielding an age of 757 Myr (+- 36 Myr at 1 sigma confidence) and a distance of 179 pc (+- 2 pc at 1 sigma confidence), not allowing for systematic errors.Comment: 22 pages, 14 figures, 9 tables, emulateapj format; Accepted for publication in The Astrophysical Journa

Genetic Susceptibility Loci of Idiopathic Interstitial Pneumonia do not Represent Risk for Systemic Sclerosis: a Case Control Study in Caucasian Patients

Background: Systemic sclerosis (SSc)-related interstitial lung disease (ILD) has phenotypic similarities to lung involvement in idiopathic interstitial pneumonia (IIP). We aimed to assess whether genetic susceptibility loci recently identified in the large IIP genome-wide association studies (GWASs) were also risk loci for SSc overall or severity of ILD in SSc. Methods: A total of 2571 SSc patients and 4500 healthy controls were investigated from the US discovery GWAS and additional US replication cohorts. Thirteen IIP-related selected single nucleotide polymorphisms (SNPs) were genotyped and analyzed for their association with SSc. Results: We found an association of SSc with the SNP rs6793295 in the LRRC34 gene (OR = 1.14, CI 95 % 1.03 to 1.25, p value = 0.009) and rs11191865 in the OBFC1 gene (OR = 1.09, CI 95 % 1.00 to 1.19, p value = 0.043) in the discovery cohort. Additionally, rs7934606 in MUC2 (OR = 1.24, CI 95 % 1.01 to 1.52, p value = 0.037) was associated with SSc-ILD defined by imaging. However, these associations failed to replicate in the validation cohort. Furthermore, SNPs rs2076295 in DSP ( β = -2.29, CI 95 % -3.85 to -0.74, p value = 0.004) rs17690703 in SPPL2C ( β = 2.04, CI 95 % 0.21 to 3.88, p value = 0.029) and rs1981997 in MAPT ( β = 2.26, CI 95 % 0.35 to 4.17, p value = 0.02) were associated with percent predicted forced vital capacity (FVC%) even after adjusting for the anti-topoisomerase (ATA)-positive subset. However, these associations also did not replicate in the validation cohort. Conclusions: Our results add new evidence that SSc and SSc-related ILD are genetically distinct from IIP, although they share phenotypic similarities

The Quintuplet Cluster I. A K-band spectral catalog of stellar sources

Three very massive clusters are known to reside in the Galactic Center region, the Arches cluster, the Quintuplet cluster and the Central parsec cluster. We obtained spectroscopic observations of the Quintuplet cluster with the Integral Field Spectrograph SINFONI-SPIFFI at the ESO-VLT. The spectral range comprises the near-IR K-band from 1.94 to 2.45 micrometer. The 3D data cubes of the individual fields were flux-calibrated and combined to one contiguous cube, from which the spectra of all detectable point sources were extracted. We present a catalog of 160 stellar sources in the inner part of the Quintuplet cluster.Comment: 14 pages, 9 figures, 3 tables, accepted by A&

Spitzer 24 um Excesses for Bright Galactic Stars in Bootes and First Look Survey Fields

Optically bright Galactic stars (V 1 mJy are identified in Spitzer mid-infrared surveys within 8.2 square degrees for the Bootes field of the NOAO Deep Wide-Field Survey and within 5.5 square degrees for the First Look Survey (FLS). 128 stars are identified in Bootes and 140 in the FLS, and their photometry is given. (K-[24]) colors are determined using K magnitudes from the 2MASS survey for all stars in order to search for excess 24 um luminosity compared to that arising from the stellar photosphere. Of the combined sample of 268 stars, 141 are of spectral types F, G, or K, and 17 of these 141 stars have 24 um excesses with (K-[24]) > 0.2 mag. Using limits on absolute magnitude derived from proper motions, at least 8 of the FGK stars with excesses are main sequence stars, and estimates derived from the distribution of apparent magnitudes indicate that all 17 are main sequence stars. These estimates lead to the conclusion that between 9% and 17% of the main sequence FGK field stars in these samples have 24 um infrared excesses. This result is statistically similar to the fraction of stars with debris disks found among previous Spitzer targeted observations of much brighter, main sequence field stars.Comment: Accepted for publication in The Astronomical Journa