828 research outputs found

    Determination of the Hubble Constant Using a Two-Parameter Luminosity Correction for Type Ia Supernovae

    Full text link
    In this paper, we make a comprehensive determination of the Hubble constant H0H_0 by using two parameters - the B-V color and the rate of decline Δm15\Delta m_{15} - to simultaneously standardize the luminosities of all nearby Cepheid-calibrated type Ia supernovae (SNe Ia) and those of a larger, more distant sample of 29 SNe Ia. Each group is treated in as similar a manner as possible in order to avoid systematic effects. A simultaneous χ2\chi ^2 minimization yields a standardized absolute luminosity of the Cepheid-calibrated supernovae as well as the Hubble constant obtained from the more distant sample. We find H0=62km/sMpc−1H_0 = 62 km/s Mpc^{-1} and a standardized absolute magnitude of -19.46. The sensitivity of H0H_0 to a metallicity dependence of the Cepheid-determined distances is investigated. The total uncertainty δH0\delta H_0, dominated by uncertainties in the primary Cepheid distance indicator, is estimated to be 5 km/s Mpc^{-1}.Comment: To appear in Ap

    Modified Tapvei OÜ Stairs Induce an Anxiolytic Effect in Female C57BL/6 Mice in the Elevated Plus-Maze Test

    Get PDF
    We evaluated the effect of modified Tapvei OÜ stairs (stairs) on the behaviour of female C57BL/6 and BALB/c mice in the elevated plus-maze (EPM) test. The mice were kept under standard conditions for 4 weeks (control) or exposed to stairs for 3 or 4 weeks, and were assessed thereafter with the EPM. The C57BL/6 mice displayed less anxiety, when compared with the BALB/c mice. Exposure to stairs had an anxiolytic effect in C57BL/6 mice, but not in BALB/c. The strain-dependent effects of stairs should be considered in the design of housing refinements and behavioural experiments

    Summary of the 13th IACHEC Meeting

    Get PDF
    We summarize the outcome of the 13th meeting of the International Astronomical Consortium for High Energy Calibration (IACHEC), held at Tenuta dei Ciclamini (Avigliano Umbro, Italy) in April 2018. Fifty-one scientists directly involved in the calibration of operational and future high-energy missions gathered during 3.5 days to discuss the current status of the X-ray payload inter-calibration and possible approaches to improve it. This summary consists of reports from the various working groups with topics ranging from the identification and characterization of standard calibration sources, multi-observatory cross-calibration campaigns, appropriate and new statistical techniques, calibration of instruments and characterization of background, and communication and preservation of knowledge and results for the benefit of the astronomical community.Comment: 12 page

    Paleolimnological evidence for increased sexual reproduction in chydorids (Chydoridae, Cladocera) under environmental stress

    Get PDF
    To investigate the extent to which anthropogenic perturbations such as eutrophication and trace metal pollution (i.e., environmental stress sensu Odum 1985) influence the reproductive modes of cladoceran populations, we analyzed the abundance of subfossils of the chydorids Alonella nana (Baird, 1850) and Alona affinis (Leydig, 1860) in sediment cores from three Finnish lakes. Reconstruction of lakes\u27 pollutant history and the biological response of chydorids indicate that in two of the lakes the proportion of individuals reproducing sexually increased with environmental stressors. More specifically, A. nana responded to eutrophication in Lake Hamptr?sk with greater production of ephippia, while A. affinis responded to aluminum pollution or acidification in Lake Pieni Majaslampi. In contrast, the reference lake, Lake Iso Lehm?lampi, showed no radical changes in sexual reproduction over the twomillennium long sediment record. We conclude that chydorids may use sexual reproduction as a strategy for overcoming unexpected environmental stresses

    Measurements and Variability of Arterial Blood Pressure and Heart Interval in Conscious and Anesthetized Dogs

    Get PDF
    No abstract availabl

    Recent changes in chironomid communities and hypolimnetic oxygen conditions relate to organic carbon in subarctic ecotonal lakes

    Get PDF
    A key question in aquatic elemental cycling is related to the influence of bottom water oxygen conditions in regulating the burial and release of carbon under climate warming. In this study, we used head capsules of Chironomidae larvae to assess community and diversity change between the past (estimated as Pre-Industrial Period) and present and to reconstruct changes in hypolimnetic oxygen conditions from 30 subarctic ecotonal lakes (northeastern Lapland) using the top-bottom paleolimnological approach applying surface sediment (topmost 0-2 cm) and reference (4-5 cm) samples. Subsequently, we tested the findings against dissolved organic carbon (DOC) concentration of the sites. We found that the benthic communities were statistically dissimilar between the past and the present with largest changes occurring in the more transparent oligo-mesohumic lakes. However, murky polyhumic lakes displayed uniformly a decrease in diversity. The chironomid-inferred oxygen values showed a general decrease toward the present with largest shifts in low-DOC lakes, whereas no significant changes were found in the hypolimnetic oxygen conditions of high-DOC lakes, which were often located in wet-land areas. These finding suggest that lakes associated with constant organic carbon inputs are more resilient toward climate-induced reductions in hypolimnetic oxygen. (c) 2018 Elsevier B.V. All rights reserved.Peer reviewe
    • …
    corecore