75 research outputs found

    Ion beam induced modification of exchange interaction and spin-orbit coupling in the Co2_2FeSi Heusler compound

    Full text link
    A Co2_2FeSi (CFS) film with L21_1 structure was irradiated with different fluences of 30 keV Ga+^+ ions. Structural modifications were subsequently studied using the longitudinal (LMOKE) and quadratic (QMOKE) magneto-optical Kerr effect. Both the coercivity and the LMOKE amplitude were found to show a similar behavior upon irradiation: they are nearly constant up to ion fluences of ≈6×1015\approx6\times10^{15} ion/cm2^2, while they decrease with further increasing fluences and finally vanish at a fluence of ≈9×1016\approx9\times10^{16} ion/cm2^2, when the sample becomes paramagnetic. However, contrary to this behavior, the QMOKE signal nearly vanishes even for the smallest applied fluence of 3×10143\times10^{14} ion/cm2^2. We attribute this reduction of the QMOKE signal to an irradiation-induced degeneration of second or higher order spin-orbit coupling, which already happens at small fluences of 30 keV Ga+^+ ions. On the other hand, the reduction of coercivity and LMOKE signal with high ion fluences is probably caused by a reduction of the exchange interaction within the film material

    Identification of fossil worm tubes from Phanerozoic hydrothermal vents and cold seeps

    Get PDF
    One of the main limitations to understanding the evolutionary history of hydrothermal vent and cold seep communities is the identification of tube fossils from ancient deposits. Tube-dwelling annelids are some of the most conspicuous inhabitants of modern vent and seep ecosystems, and ancient vent and seep tubular fossils are usually considered to have been made by annelids. However, the taxonomic affinities of many tube fossils from vents and seeps are contentious, or have remained largely undetermined due to difficulties in identification. In this study, we make a detailed chemical (Fourier-transform infrared spectroscopy and pyrolysis gas-chromatography mass-spectrometry) and morphological assessment of modern annelid tubes from six families, and fossil tubes (seven tube types from the Cenozoic, 12 Mesozoic and four Palaeozoic) from hydrothermal vent and cold seep environments. Characters identified from these investigations were used to explore for the first time the systematics of ancient vent and seep tubes within a cladistic framework. Results reveal details of the compositions and ultrastructures of modern tubes, and also suggest that two types of tubes from ancient vent localities were made by the annelid family Siboglinidae, which often dominates modern vents and seeps. Our results also highlight that several vent and seep tube fossils formerly thought to have been made by annelids cannot be assigned an annelid affiliation with any certainty. The findings overall improve the level of quality control with regard to interpretations of fossil tubes, and, most importantly, suggest that siboglinids likely occupied Mesozoic vents and seeps, greatly increasing the minimum age of the clade relative to earlier molecular estimates

    Npl3 functions in mRNP assembly by recruitment of mRNP components to the transcription site and their transfer onto the mRNA

    Get PDF
    RNA-binding proteins (RBPs) control every RNA metabolic process by multiple protein-RNA and protein-protein interactions. Their roles have largely been analyzed by crude mutations, which abrogate multiple functions at once and likely impact the structural integrity of the large ribonucleoprotein particles (RNPs) these proteins function in. Using UV-induced RNA-protein crosslinking of entire cells, protein complex purification and mass spectrometric analysis, we identified >100 in vivo RNA crosslinks in 16 nuclear mRNP components in Saccharomyces cerevisiae. For functional analysis, we chose Npl3, which displayed crosslinks in its two RNA recognition motifs (RRMs) and in the connecting flexible linker region. Both RRM domains and the linker uniquely contribute to RNA recognition as revealed by NMR and structural analyses. Interestingly, mutations in these regions cause different phenotypes, indicating distinct functions of the different RNA-binding domains. Notably, an npl3-Linker mutation strongly impairs recruitment of several mRNP components to chromatin and incorporation of other mRNP components into nuclear mRNPs, establishing a so far unknown function of Npl3 in nuclear mRNP assembly. Taken together, our integrative analysis uncovers a specific function of the RNA-binding activity of the nuclear mRNP component Npl3. This approach can be readily applied to RBPs in any RNA metabolic process

    2001 New York State NHTS: Travel Patterns of Special Populations

    No full text
    Policymakers rely on transportation statistics, including data on personal travel behavior, to formulate strategic transportation policies, and to improve the safety and efficiency of the U.S. transportation system. Data on personal travel trends are needed to examine the reliability, efficiency, capacity, and flexibility of the Nation's transportation system to meet current demands and accommodate future demands; to assess the feasibility and efficiency of alternative congestion-alleviating technologies (e.g., high-speed rail, magnetically levitated trains, intelligent vehicle and highway systems); to evaluate the merits of alternative transportation investment programs; and to assess the energy-use and air-quality impacts of various policies. To address these data needs, the U.S. Department of Transportation (USDOT) initiated an effort in 1969 to collect detailed data on personal travel. The 1969 survey was the first Nationwide Personal Transportation Survey (NPTS). The survey was conducted again in 1977, 1983, 1990, 1995, and 2001. Data on daily travel were collected in 1969, 1977, 1983, 1990 and 1995. Longer-distance travel was collected in 1977 and 1995. The 2001 National Household Travel Survey (NHTS) collected both daily and longer-distance trips in one survey. The 2001 survey was sponsored by three USDOT agencies: Federal Highway Administration (FHWA), Bureau of Transportation Statistics (BTS), and National Highway Traffic Safety Administration (NHTSA). The primary objective of the survey was to collect trip-based data on the nature and characteristics of personal travel so that the relationships between the characteristics of personal travel and the demographics of the traveler can be established. Commercial and institutional travel was not part of the survey. New York State participated in the 2001 NHTS by procuring additional 12,000 sample households. These additional sample households allowed New York State to address transportation planning issues pertinent to geographic areas that are significantly smaller than what the national NHTS data allowed. The final sample size for New York State was 13,423 usable households. In this report, Oak Ridge National Laboratory (ORNL) identifies and analyzes differences, if any, in travel patterns that are attributable to demographic characteristics (e.g., gender, age, race and ethnicity), household characteristics (e.g., low income households, zero and one car households), modal characteristics and geographic location. Travel patterns of those who work at home are examined and compared to those of conventional workers, as well as those who do not work. Focus is given to trip frequency, travel by time of day, trip purpose, and mode choice. For example, included in this analysis is the mobility of the elderly population in New York State. The American society is undergoing a major demographic transformation that is resulting in a greater percentage of older individuals in the population. In addition to demographic changes, recent travel surveys show that an increasing number of older individuals are licensed to drive and that they drive more than their same age cohort did a decade ago. Cohort differences in driving are particularly apparent - not only are more of today's elderly population licensed to drive than their age cohort two decades ago, they also drive more. Equally important are the increase in immigration and in racial and cultural diversity. This report also discusses vehicle availability, socioeconomic characteristics, travel trends (e.g., miles travelled, distance driven, commute patterns), and the transportation accessibility of these populations. Specifically, this report addresses in detail the travel behavior of the following special populations: (1) the elderly, defined as those who were 65 years old or older, (2) low-income households, (3) ethnic groups and immigrants, and (4) those who worked at home
    • …
    corecore