3,608 research outputs found

    OGO-6 gas-surface energy transfer experiment

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    The kinetic energy flux of the upper atmosphere was analyzed using OGO-6 data. Energy transfer between 10 microwatts/sq cm and 0.1 W/sq cm was measured by short-term frequency changes of temperature-sensitive quartz crystals used in the energy transfer probe. The condition of the surfaces was continuously monitored by a quartz crystal microbalance to determine the effect surface contamination had on energy accommodation. Results are given on the computer analysis and laboratory tests performed to optimize the operation of the energy transfer probe. Data are also given on the bombardment of OGO-6 surfaces by high energy particles. The thermoelectrically-cooled quartz crystal microbalance is described in terms of its development and applications

    Designing zeolite catalysts for shape-selective reactions: Chemical modification of surfaces for improved selectivity to dimethylamine in synthesis from methanol and ammonia

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    The relative contributions of external and intracrystalline acidic sites of small pore H-RHO zeolite for the selective synthesis of methylamines from methanol and ammonia have been studied. Nonselective surface reactions which produce predominantly trimethylamine can be eliminated by “capping” the external acidic sites with trimethylphosphite (TMP) and other reagents, thus improving the selectivity toward the formation of dimethylamine. For small pore zeolites, neither the zeolite pore size nor the internal acidic sites is significantly affected by this treatment. In situ infrared and MAS-NMR studies show that TMP reacts irreversibly with the zeolite acidic sites via a modified Arbusov rearrangement to form surface-bound dimethylmethylphosphonate

    Hubble Space Telescope Imaging of the Ultracompact Blue Dwarf Galaxy HS 0822+3542: An Assembling Galaxy in a Local Void?

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    We present deep U, narrow-V, and I-band images of the ultracompact blue dwarf galaxy HS 0822+3542, obtained with the Advanced Camera for Surveys / High Resolution Channel of the Hubble Space Telescope. This object is extremely metal-poor (12 + log(O/H) = 7.45) and resides in a nearby void. The images resolve it into two physically separate components that were previously described as star clusters in a single galaxy. The primary component is only \~100 pc in maximum extent, and consists of starburst region surrounded by a ring-like structure of relatively redder stars. The secondary component is ~50 pc in size and lies at a projected distance of ~80 pc away from the primary, and is also actively star-forming. We estimate masses ~10^7 M(sol) and ~10^6 M(sol) for the two components, based on their luminosities, with an associated dynamical timescale for the system of a few Myr. This timescale and the structure of the components suggests that a collision between them triggered their starbursts. The spectral energy distributions of both components can be fitted by the combination of recent (few Myr old) starburst and an evolved (several Gyr old) underlying stellar population, similar to larger blue compact dwarf galaxies. This indicates that despite its metal deficiency the object is not forming its first generation of stars. However, the small sizes and masses of the two components suggests that HS 0822+3542 represents a dwarf galaxy in the process of assembling from clumps of stars intermediate in size between globular clusters and objects previously classified as galaxies. Its relatively high ratio of neutral gas mass to stellar mass (~1) and high specific star formation rate, log(SFR/M(sol) = -9.2, suggests that it is still converting much of its gas to stars.Comment: 11 pages, 2 figures, accepted for publication in Astrophysical Journal Letter

    Two Classes of cAMP Analogs Which Are Selective for the Two Different cAMP-Binding Sites of Type II Protein Kinase Demonstrate Synergism When Added Together to Intact Adipocytes

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    Twenty-five cyclic nucleotide analogs were tested individually to act as lipolytic agents and to activate adipocyte protein kinase. The lipolytic potency of individual analogs correlated better with their K(a) for protein kinase and their lipophilicity rather than with either parameters alone. Some of the most potent lipolytic analogs had high I50 values for the particulate low K(m) cAMP phosphodiesterase suggesting that their effect was not due to raising endogenous cAMP levels through inhibition of phosphodiesterase. The most potent lipolytic analogs contained a thio moiety at the C-8 or C-6 position. These analogs exhibited concave upward dose-response curves. At high concentrations some analogs were as effective as optimal concentrations of epinephrine in stimulating glycerol release. The regulatory subunit of protein kinase has two different intrachain cAMP-binding sites and cAMP analogs modified at the C-8 position (C-8 analogs) are generally selective for Site 1 and analogs modified at the C-6 position (C-6 analogs) are generally selective for Site 2 (Rannels, S.R., and Corbin, J.D. (1980) J. Biol. Chem. 255, 7085-7088). Thus, C-8 and C-6 analogs were tested in combination to stimulate lipolysis in intact adipocytes and to activate protein kinase in vitro. Each process was stimulated synergistically by a combination of a C-6 and C-8 analog. Two C-8 analogs or two C-6 analogs added together did not cause synergism of either process. For both lipolysis and protein kinase activation, C-8 thio analogs acted more synergistically than C-8 amino analogs when incubated in combination with C-6 analogs, a characteristic of type II protein kinase. It is concluded that the observed synergism of lipolysis is due to binding of cAMP analogs to both intrachain sites and that it is the type II protein kinase isozyme which is responsible for the lipolytic response

    Microheterogeneity of Type II cAMP-Dependent Protein Kinase in Various Mammalian Species and Tissues

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    Excluding autophosphorylated species, at least six forms of the regulatory subunit of type II cAMP-dependent protein kinase (R(II)) from various mammalian tissues were identified by sodium dodecyl sulfate (SDS) gel electrophoresis of purified samples and of crude preparations photoaffinity labeled with 8-azido[32P] cAMP and by gel filtration. After autophosphorylation some heart R(II) forms termed type IIA (bovine, porcine, equine, and dog) shifted to a more slowly migrating band on SDS gels while others termed type IIB (rat, guinea pig, rabbit, and monkey) did not detectably shift. Both subclasses of R(II) exhibited variation in apparent M(r) on SDS gels. Bovine and porcine heart nonautophosphorylated R(II) had M(r) 56,000 and the autophosphorylated R(II) had M(r) 58,000, while dog and equine heart R(II) had M(r) 54,000 and 56,000 for these bands, respectively. Rat heart R(II) had M(r) 56,000 while rabbit and guinea pig heart R(II) had M(r) 52,000. More than one R(II) was found in different tissues of the same species. Rabbit skeletal muscle contained a M(r) 56,000 IIB form. Bovine lung contained almost equal amounts of a IIA form apparently identical to that of bovine heart and a M(r) 52,000 IIB form similar to that which predominated in bovine brain. Rat adipose tissue, brain, and monkey heart contained predominantly a M(r) 51,000 IIB form. The rat liver M(r) 56,000 IIB form chromatographed differently from all other R(II) tested by gel filtration. Several lines of evidence indicated that the various forms of R(II) were not derived from one another through proteolysis or other processes. Each of the type II forms rapidly incorporated 0.3-1.0 mol of 32P per mol of subunit when incubated with [Îł-32P]ATP and C subunit. Four of the forms tested were similar in the cAMP concentration dependence for activation of their corresponding holoenzymes and inhibited C subunit about equally. Each exhibited two components of [3H]cAMP dissociation, indicating two intrachain cAMP-binding sites, and the dissociation rates for the respective sites, and the dissociation rates for the respective sites were similar

    Blaming Bill Gates AGAIN! Misuse, overuse and misunderstanding of performance data in sport

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    Recently in Sport, Education and Society, Williams and Manley (2014) argued against the heavy reliance on technology in professional Rugby Union and elite sport in general. In summary, technology is presented as an elitist, ‘gold standard’ villain that management and coaches use to exert control and by which players lose autonomy, identity, motivation, social interactions and expertise. In this article we suggest that the sociological interpretations and implications offered by Williams and Manley may be somewhat limited when viewed in isolation. In doing so, we identify some core methodological issues in Williams and Manley’s study and critically consider important arguments for utilising technology; notably, to inform coach decision making and generate player empowerment. Secondly, we present a different, yet perhaps equally concerning, practice-oriented interpretation of the same results but from alternative coaching and expertise literature. Accordingly, we suggest that Williams and Manley have perhaps raised their alarm prematurely, inappropriately and on somewhat shaky foundations. We also hope to stimulate others to consider contrary positions, or at least to think about this topic in greater detail. More specifically, we encourage coaches and academics to think carefully about what technology is employed, how and why, and then the means by which these decisions are discussed with and, preferably, sold to players. Certainly, technology can significantly enhance coach decision making and practice, while also helping players to optimise their focus, empowerment and independence in knowing how to achieve their personal and collective goals

    Linking Physical Education With Community Sport and Recreation: A Program for Adolescent Girls

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    The engagement of adolescent girls in physical activity (PA) is a persistent challenge. School-based PA programs have often met with little success because of the lack of linkages between school and community PA settings. The Triple G program aimed to improve PA levels of secondary school girls (12-15 years) in regional Victoria, Australia. The program included a school-based physical education (PE) component that uniquely incorporated student-centered teaching and behavioral skill development. The school component was conceptually and practically linked to a community component that emphasized appropriate structures for participation. The program was informed by ethnographic fieldwork to understand the contextual factors that affect girls’ participation in PA. A collaborative intervention design was undertaken to align with PE curriculum and coaching and instructional approaches in community PA settings. The theoretical framework for the intervention was the socioecological model that was underpinned by both individual-level (social cognitive theory) and organizational-level (building organizational/community capacity) strategies. The program model provides an innovative conceptual framework for linking school PE with community sport and recreation and may benefit other PA programs seeking to engage adolescent girls. The objective of this article is to describe program development and the unique theoretical framework and curriculum approaches
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