677 research outputs found

    Managing Alaska Soils

    Get PDF
    This publication is for the gardener who wants to gain a more thorough understanding of soil basics, including soil components, texture, structure, water permeability and chemistry. There is also information on soil fertility and plant nutrients.This publication replaces the following Extension publications: Soil Fundamentals by C.L. Johnson, former Extension Assistant, Palmer Research Station, University of Alaska Fairbanks and Soil Fertility Basics and Soil Sampling and Analysis by J.L. Walworth, former Soil Scientist, Agricultural and Forestry Experiment Station, Palmer Research Center, University of Alaska Fairbanks

    Factors to Consider in Selecting a Soil Testing Lab

    Get PDF
    This factsheet provides guidelines for selecting which tests one should use and finding soil testing laboratories that perform those tests. It is a fantastic tool for Alaskans as it highlights available options for tests, types of tests and testing facilities. Laboratory contact information is included.This publication was prepared by Peter Bierman and Thomas R. Jahns, former Extension Faculty, Agriculture and Horticulture

    Phasespace Correlations of Antideuterons in Heavy Ion Collisions

    Get PDF
    In the framework of the relativistic quantum molecular dynamics approach ({\small RQMD}) we investigate antideuteron (d‾\overline{d}) observables in Au+Au collisions at 10.7~AGeV. The impact parameter dependence of the formation ratios d‾/p‾2\overline{d}/\overline{p}^2 and d/p2{d}/{p}^2 is calculated. In central collisions, the antideuteron formation ratio is predicted to be two orders of magnitude lower than the deuteron formation ratio. The d‾\overline{d} yield in central Au+Au collisions is one order of magnitude lower than in Si+Al collisions. In semicentral collisions different configuration space distributions of p‾\overline{p}'s and d‾\overline{d}'s lead to a large ``squeeze--out'' effect for antideuterons, which is not predicted for the p‾\overline{p}'s

    Paper Session II-B - Life Sciences Shuttle Flights- 15 Years

    Get PDF
    Fifteen years ago, the first Life Sciences Announcement of Opportunity offered the promises of man-tended microgravity flights. For the experiments involving nonhuman elements, i.e., plants, animals, tissues and cells, the Shuttle Transportation System (STS) flights posed both challenges and rewards. The transition from the 1-G laboratory bench to O-G environment has resulted in new information with each succeeding flight. These rewards are measured both in better understanding in methods and materials to conduct research within the microgravity milieu and interpretation of the data obtained. The engineering systems developed, operational knowledge gained over the past 15 years, and data base of experimental results being developed, can only enhance, support, and stimulate the scientific community\u27s sights toward NASA\u27s next direction - Space Station Freedom

    Unmasking features of the auto-epitope essential for β(1)-adrenoceptor activation by autoantibodies in chronic heart failure

    Get PDF
    AIMS: Chronic heart failure (CHF) can be caused by autoantibodies stimulating the heart via binding to first and/or second extracellular loops of cardiac β(1)-adrenoceptors. Allosteric receptor activation depends on conformational features of the autoantibody binding site. Elucidating these features will pave the way for the development of specific diagnostics and therapeutics. Our aim was (i) to fine-map the conformational epitope within the second extracellular loop of the human β(1)-adrenoceptor (β(1) EC(II)) that is targeted by stimulating β(1)-receptor (auto)antibodies and (ii) to generate competitive cyclopeptide inhibitors of allosteric receptor activation, which faithfully conserve the conformational auto-epitope. METHODS AND RESULTS: Non-conserved amino acids within the β(1) ECII loop (compared with the amino acids constituting the ECII loop of the β(2)-adrenoceptor) were one by one replaced with alanine; potential intra-loop disulfide bridges were probed by cysteine-serine exchanges. Effects on antibody binding and allosteric receptor activation were assessed (i) by (auto)antibody neutralization using cyclopeptides mimicking β(1) ECII ± the above replacements, and (ii) by (auto)antibody stimulation of human β(1)-adrenoceptors bearing corresponding point mutations. With the use of stimulating β(1)-receptor (auto)antibodies raised in mice, rats, or rabbits and isolated from exemplary dilated cardiomyopathy patients, our series of experiments unmasked two features of the β(1) ECII loop essential for (auto)antibody binding and allosteric receptor activation: (i) the NDPK(211-214) motif and (ii) the intra-loop disulfide bond C(209)↔C(215). Of note, aberrant intra-loop disulfide bond C(209)↔C(216) almost fully disrupted the functional auto-epitope in cyclopeptides. CONCLUSIONS: The conformational auto-epitope targeted by cardio-pathogenic β(1)-receptor autoantibodies is faithfully conserved in cyclopeptide homologues of the β(1) EC(II) loop bearing the NDPK(211-214) motif and the C(209)↔C(215) bridge while lacking cysteine C(216). Such molecules provide promising tools for novel diagnostic and therapeutic approaches in β(1)-autoantibody-positive CHF

    On the analysis of non-photochemical chlorophyll fluorescence quenching curves I. Theoretical considerations

    Get PDF
    AbstractNon-photochemical quenching (NPQ) protects photosynthetic organisms against photodamage by high light. One of the key measuring parameters for characterizing NPQ is the high-light induced decrease in chlorophyll fluorescence. The originally measured data are maximal fluorescence (Fm′) signals as a function of actinic illumination time (Fm′(t)). Usually these original data are converted into the so-called Stern–Volmer quenching function, NPQSV(t), which is then analyzed and interpreted in terms of various NPQ mechanisms and kinetics. However, the interpretation of this analysis essentially depends on the assumption that NPQ follows indeed a Stern–Volmer relationship. Here, we question this commonly assumed relationship, which surprisingly has never been proven. We demonstrate by simulation of quenching data that particularly the conversion of time-dependent quenching curves like Fm′(t) into NPQSV(t) is (mathematically) not “innocent” in terms of its effects. It distorts the kinetic quenching information contained in the originally measured function Fm′(t), leading to a severe (often sigmoidal) distortion of the time-dependence of quenching and has negative impact on the ability to uncover the underlying quenching mechanisms and their contribution to the quenching kinetics. We conclude that the commonly applied analysis of time-dependent NPQ in NPQSV(t) space should be reconsidered. First, there exists no sound theoretical basis for this common practice. Second, there occurs no loss of information whatsoever when analyzing and interpreting the originally measured Fm′(t) data directly. Consequently, the analysis of Fm′(t) data has a much higher potential to provide correct mechanistic answers when trying to correlate quenching data with other biochemical information related to quenching

    The rodent research animal holding facility as a barrier to environmental contamination

    Get PDF
    The rodent Research Animal Holding Facility (RAHF), developed by NASA Ames Research Center (ARC) to separately house rodents in a Spacelab, was verified as a barrier to environmental contaminants during a 12-day biocompatibility test. Environmental contaminants considered were solid particulates, microorganisms, ammonia, and typical animal odors. The 12-day test conducted in August 1988 was designed to verify that the rodent RAHF system would adequately support and maintain animal specimens during normal system operations. Additional objectives of this test were to demonstrate that: (1) the system would capture typical particulate debris produced by the animal; (2) microorganisms would be contained; and (3) the passage of animal odors was adequately controlled. In addition, the amount of carbon dioxide exhausted by the RAHF system was to be quantified. Of primary importance during the test was the demonstration that the RAHF would contain particles greater than 150 micrometers. This was verified after analyzing collection plates placed under exhaust air ducts and rodent cages during cage maintenance operations, e.g., waste tray and feeder changeouts. Microbiological testing identified no additional organisms in the test environment that could be traced to the RAHF. Odor containment was demonstrated to be less than barely detectable. Ammonia could not be detected in the exhaust air from the RAHF system. Carbon dioxide levels were verified to be less than 0.35 percent

    Antibaryons in massive heavy ion reactions: Importance of potentials

    Get PDF
    In the framework of RQMD we investigate antiproton observables in massive heavy ion collisions at AGS energies and compare to preliminary results of the E878 collaboration. We focus here on the considerable influence of the *real* part of an antinucleon--nucleus optical potential on the antiproton momentum spectra

    How limiting is optical follow-up for fast radio burst applications? Forecasts for radio and optical surveys

    Get PDF
    Fast radio bursts (FRBs) are the first cosmological radio sources that vary on millisecond timescales, which makes them a unique probe of the Universe. Many proposed applications of FRBs require associated redshifts. These can only be obtained by localizing FRBs to their host galaxies and subsequently measuring their redshifts. Upcoming FRB surveys will provide arcsecond localization for many FRBs, not all of which can be followed up with dedicated optical observations. We aim to estimate the fraction of FRB hosts that will be catalogued with redshifts by existing and future optical surveys. We use the population synthesis code frbpoppy to simulate several FRB surveys, and the semi-analytical galaxy formation code GALFORM to simulate their host galaxies. We obtain redshift distributions for the simulated FRBs and the fraction with host galaxies in a survey. Depending on whether FRBs follow the cosmic star formation rate or stellar mass, 20 to 40 per cent of CHIME FRB hosts will be observed in an SDSS-like survey, all at z<0.5z<0.5. The deeper DELVE survey will detect 63 to 85 per cent of ASKAP FRBs found in its coherent search mode. CHIME FRBs will reach z∼3z\sim 3, SKA1-Mid FRBs z∼5z\sim 5, but ground based follow-up is limited to z≲1.5z\lesssim 1.5. We discuss consequences for several FRB applications. If ∼1/2\sim1/2 of ASKAP FRBs have measured redshifts, 1000 detected FRBs can be used to constrain Ωbh70\Omega_\text{b} h_{70} to within ∼10\sim10 per cent at 95 per cent credibility. We provide strategies for optimized follow-up, when building on data from existing surveys. Data and codes are made available.Comment: 18 pages, 16 figures, 4 tables, accepted for publication in MNRAS. Code available at https://github.com/JoschaJ/mockFRBhost
    • …
    corecore