3,653 research outputs found

    Analysis of Gray Fox (Urocyon cinereoargenteus) Fur Harvests in Arkansas

    Get PDF
    An investigation was conducted on gray fox (Urocyon cinereoargenteus) fur harvest in Arkansas. Data were gathered from a mail survey of Arkansas trappers and from Arkansas Game and Fish Commission fur harvest records from 1939 to 1983. Analyses of these data demonstrated: 1) gray fox were abundant statewide with lower levels in the Delta region; 2) there was a need for fox trappers to keep better records on their trapping efforts, success and composition of catch, including sex and age data; 3) market price: harvest correlation was high (r = 0.956, p \u3c .001); 4) over the past 10 years, the Ozark Mountain region provided the greatest contribution to annual fox harvests, the Ouachita Mountain and Gulf Coastal Plain regions were similar to each other, but lower than the Ozarks, and the Delta region contributed the least, but with a generally stable harvest

    Palladium-bismuth intermetallic and surface-poisoned catalysts for the semi-hydrogenation of 2-methyl-3-butyn-2-ol

    Get PDF
    The effects of poisoning of Pd catalysts with Bi and annealing in a polyol (ethylene glycol) were studied on the semi-hydrogenation of 2-methyl-3-butyn-2-ol (MBY). An increase in the Pd:Bi ratio from 7 to 1 in the Bi-poisoned catalysts decreased the hydrogenation activity due to blocking of active sites, but increased maximum alkene yield from 91.5% for the Pd catalyst to 94–96% for all Bi-poisoned Pd catalysts, by decreasing the adsorption energy of alkene molecules and suppressing the formation of β-hydride phase. Annealing of the catalysts induced the formation of intermetallic phases and decreased its activity due to sintering of the catalytic particles and low activity of intermetallic compounds. Langmuir–Hinshelwood kinetic modelling of the experimental data showed that poisoning of Pd with Bi changed the relative adsorption constants of organic species suggesting ligand effects at high Bi content

    The DUB/USP17 deubiquitinating enzymes: A gene family within a tandemly repeated sequence, is also embedded within the copy number variable Beta-defensin cluster

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>The DUB/USP17 subfamily of deubiquitinating enzymes were originally identified as immediate early genes induced in response to cytokine stimulation in mice (DUB-1, DUB-1A, DUB-2, DUB-2A). Subsequently we have identified a number of human family members and shown that one of these (DUB-3) is also cytokine inducible. We originally showed that constitutive expression of DUB-3 can block cell proliferation and more recently we have demonstrated that this is due to its regulation of the ubiquitination and activity of the 'CAAX' box protease RCE1.</p> <p>Results</p> <p>Here we demonstrate that the human DUB/USP17 family members are found on both chromosome 4p16.1, within a block of tandem repeats, and on chromosome 8p23.1, embedded within the copy number variable beta-defensin cluster. In addition, we show that the multiple genes observed in humans and other distantly related mammals have arisen due to the independent expansion of an ancestral sequence within each species. However, it is also apparent when sequences from humans and the more closely related chimpanzee are compared, that duplication events have taken place prior to these species separating.</p> <p>Conclusions</p> <p>The observation that the DUB/USP17 genes, which can influence cell growth and survival, have evolved from an unstable ancestral sequence which has undergone multiple and varied duplications in the species examined marks this as a unique family. In addition, their presence within the beta-defensin repeat raises the question whether they may contribute to the influence of this repeat on immune related conditions.</p

    CARBON AND NITROGEN BALANCE OF CHLORELLA DURING GROWTH

    Full text link

    Acoustic Absorption in Porous Materials

    Get PDF
    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber

    A Relationship Between Constraint and the Critical Crack Tip Opening Angle

    Get PDF
    Of the various approaches used to model and predict fracture, the Crack Tip Opening Angle (CTOA) fracture criterion has been successfully used for a wide range of two-dimensional thin-sheet and thin plate applications. As thicker structure is considered, modeling the full three-dimensional fracture process will become essential. This paper investigates relationships between the local CTOA evaluated along a three-dimensional crack front and the corresponding local constraint. Previously reported tunneling crack front shapes were measured during fracture by pausing each test and fatigue cycling the specimens to mark the crack surface. Finite element analyses were run to model the tunneling shape during fracture, with the analysis loading conditions duplicating those tests. The results show an inverse relationship between the critical fracture value and constraint which is valid both before maximum load and after maximum load

    Equity Returns to Small Bank Investors

    Get PDF
    Unlike most other small firms, there is an excellent record of the initial equity capitalization details of banking organizations when they are formed, as well as subsequent changes, because of the chartering application and reporting requirements of the banking regulatory authorities. By combining these records with the actual approved acquisition price of small banks, the return received by small bank investors from the time of organization through acquisition is determined. For small banks organized after 1972 and acquired from 1980 and through 1988, yearly mean rates of return ranged from 23.07 percent to 10.49 percent. Generally, these returns exceed S&P 500 returns for similar holding periods, but on a Sharpe Performance Index risk adjusted basis were inferior to S&P portfolios in six of nine holding periods and consistently weaker by the same measure to small company investment on the NYSE for this entire period. This inferior risk adjusted performance was unexpected

    Tracing Galaxy Formation with Stellar Halos II: Relating Substructure in Phase- and Abundance-Space to Accretion Histories

    Get PDF
    This paper explores the mapping between the observable properties of a stellar halo in phase- and abundance-space and the parent galaxy's accretion history in terms of the characteristic epoch of accretion and mass and orbits of progenitor objects. The study utilizes a suite of eleven stellar halo models constructed within the context of a standard LCDM cosmology. The results demonstrate that coordinate-space studies are sensitive to the recent (0-8 Gyears ago) merger histories of galaxies (this timescale corresponds to the last few to tens of percent of mass accretion for a Milky-Way-type galaxy). Specifically, the {\it frequency, sky coverage} and {\it fraction of stars} in substructures in the stellar halo as a function of surface brightness are indicators of the importance of recent merging and of the luminosity function of infalling dwarfs. The {\it morphology} of features serves as a guide to the orbital distribution of those dwarfs. Constraints on the earlier merger history (> 8 Gyears ago) can be gleaned from the abundance patterns in halo stars: within our models, dramatic differences in the dominant epoch of accretion or luminosity function of progenitor objects leave clear signatures in the [alpha/Fe] and [Fe/H] distributions of the stellar halo - halos dominated by very early accretion have higher average [alpha/Fe], while those dominated by high luminosity satellites have higher [Fe/H]. This intuition can be applied to reconstruct much about the merger histories of nearby galaxies from current and future data sets.Comment: 21 pages, 20 figures. To appear in the Astrophysical Journa

    The Effect of Substructure on Mass Estimates of Galaxies

    Full text link
    Large galaxies are thought to form hierarchically, from the accretion and disruption of many smaller galaxies. Such a scenario should naturally lead to galactic phase-space distributions containing some degree of substructure. We examine the errors in mass estimates of galaxies and their dark halos made using the projected phase-space distribution of a tracer population (such as a globular cluster system or planetary nebulae) due to falsely assuming that the tracers are distributed randomly. The level of this uncertainty is assessed by applying a standard mass estimator to samples drawn from 11 random realizations of galaxy halos containing levels of substructure consistent with current models of structure formation. We find that substructure will distort our mass estimates by up to ~20% - a negligible error compared to statistical and measurement errors in current derivations of masses for our own and other galaxies. However, this represents a fundamental limit to the accuracy of any future mass estimates made under the assumption that the tracer population is distributed randomly, regardless of the size of the sample or the accuracy of the measurements.Comment: 9 pages, 8 figures, Astrophysical Journal, in pres
    • …
    corecore