1,235 research outputs found

    Complete cDNA sequence for rabbit muscle glycogen phosphorylase

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    AbstractThe cDNA for the nearly full-length rabbit muscle glycogen phosphorylase mRNA has been isolated and sequenced. The cDNA is rich in G and C nucleotides. This feature is especially striking at the 3rd position of codons, where 86% of the 843 amino acid codons terminate with G or C. Methionine, presumably the initiation residue, is found at position—1, suggesting that the removal of only a single methionine residue precedes the amino-terminal acetylation at serine. Eight differences between the deduced amino acid sequence and the previously determined protein sequence are discussed

    The Primordial Perturbation Spectrum from Various Expanding and Contracting Phases

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    In this paper, focusing on the case of single scalar field, we discuss various expanding and contracting phases generating primordial perturbations, and study the relation between the primordial perturbation spectrum from these phases and the parameter w of state equation in details. Furthermore, we offer an interesting classification for the primordial perturbation spectrum from various phases, which may have important implications for building an early universe scenario embedded in possible high energy theories.Comment: 5 pages, 3 eps figure

    Effect of Pre-Exercise Nutrition on Human Skeletal Muscle UCP3 Expression

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    BACKGROUND: Increased UCP3 expression in skeletal muscle after exercise may be attributed to elevated free fatty acids (FFA) that are known to directly activate UCP3 expression. Pre-exercise glucose consumption has shown to blunt UCP3 expression in response to exercise. Since glucose ingestion before and during exercise is typically not a common practice, the goal of the present study was to assess the effect of a multi-macronutrient meal (drinkable shake) in the pre-exercise period towards human skeletal muscle UCP3 expression. METHODS: Using a crossover design, untrained participants performed an endurance exercise session (350 kcal at 70% of their VO2max) after two experimental conditions 1) consumption of a multi-macronutrient meal and 2) a fasting period of 8 h. Blood samples were taken at baseline, pre-exercise, post-exercise, 1h, and 4h post-exercise, while muscle biopsies were taken at the last four time points. RESULTS: A significant increase in FFA was observed in the fasting condition (p= 0.046) as well as a significant increase in UCP3 mRNA and protein expression at post-exercise (p= 0.042) and 4 h post-exercise (p= 0.036) respectively, in the multi-macronutrient meal condition. DISCUSSION: Variables showed a total opposite response to what has been reported after the consumption of pure glucose before an exercise session. Instead of observing a decrease in UCP3 expression in the non-fasting condition, we observed a significant increase in UCP3 mRNA and protein concentration in the multi-macronutrient condition. According to previous research, variables such as the protein and fat content from the multi-macronutrient meal, as well as the insulin levels, could have played key roles in altering UCP3 mRNA and protein expression in the multi-macronutrient condition; however, further research is needed to confirm this hypothesis. CONCLUSION: The expression of UCP3 mRNA and protein expression as a result of exercise might be controlled by factors other than FFA

    Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea

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    Breakup of the near-continuous winter sea ice into discrete summer ice floes is an important transition that dictates the evolution and fate of the marginal ice zone (MIZ) of the Arctic Ocean. During the winter of 2014, more than 50 autonomous drifting buoys were deployed in four separate clusters on the sea ice in the Beaufort Sea, as part of the Office of Naval Research MIZ program. These systems measured the ocean-ice-atmosphere properties at their location whilst the sea ice parameters in the surrounding area of these buoy clusters were continuously monitored by satellite TerraSAR-X Synthetic Aperture Radar. This approach provided a unique Lagrangian view of the winter-to-summer transition of sea ice breakup and floe size distribution at each cluster between March and August. The results show the critical timings of a) temporary breakup of winter sea ice coinciding with strong wind events and b) spring breakup (during surface melt, melt ponding and drainage) leading to distinctive summer ice floes. Importantly our results suggest that summer sea ice floe distribution is potentially affected by the state of winter sea ice, including the composition and fracturing (caused by deformation events) of winter sea ice, and that substantial mid-summer breakup of sea ice floes is likely linked to the timing of thermodynamic melt of sea ice in the area. As the rate of deformation and thermodynamic melt of sea ice has been increasing in the MIZ in the Beaufort Sea, our results suggest that these elevated factors would promote faster and more enhanced breakup of sea ice, leading to a higher melt rate of sea ice and thus a more rapid advance of the summer MIZ

    Comment on "Density perturbations in the ekpyrotic scenario"

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    In the paper ``Density perturbations in the ekpyrotic scenario'', it is argued that the expected spectrum of primordial perturbations should be scale invariant in this scenario. Here we show that, contrary to what is claimed in that paper, the expected spectrum depends on an arbitrary choice of matching variable. As no underlying (microphysical) principle exists at the present time that could lift the arbitrariness, we conclude that the ekpyrotic scenario is not yet a predictive model.Comment: 4 pages, no figure, RevTeX, commenting on hep-th/010905

    Flexible antibodies with nonprotein hinges

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    There is a significant need for antibodies that can bind targets with greater affinity. Here we describe a novel strategy employing chemical semisynthesis to produce symmetroadhesins: antibody-like molecules having nonprotein hinge regions that are more flexible and extendible and are capable of two-handed binding. Native chemical ligation was carried out under mild, non-denaturing conditions to join a ligand binding domain (Aβ peptide) to an IgG1 Fc dimer via discrete oxyethylene oligomers of various lengths. Two-handed Aβ–Fc fusion proteins were obtained in quantitative yield and shown by surface plasmon resonance to bind an anti-Aβ antibody with a KD at least two orders of magnitude greater than the cognate Aβ peptide. MALDI-TOF MS analysis confirmed the protein/nonprotein/protein structure of the two-handed molecules, demonstrating its power to characterize complex protein-nonprotein hybrids by virtue of desorption/ionization mediated by peptide sequences contained therein. We anticipate many applications for symmetroadhesins that combine the target specificity of antibodies with the novel physical, chemical and biological properties of nonprotein hinges

    Vortex Fluctuations in High-Tc Films: Flux Noise Spectrum and Complex Impedance

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    The flux noise spectrum and complex impedance for a 500 {\AA} thick YBCO film are measured and compared with predictions for two dimensional vortex fluctuations. It is verified that the complex impedance and the flux noise spectra are proportional to each other, that the logarithm of the flux noise spectra for different temperatures has a common tangent with slope 1\approx -1, and that the amplitude of the noise decreases as d3d^{-3}, where dd is the height above the film at which the magnetic flux is measured. A crossover from normal to anomalous vortex diffusion is indicated by the measurements and is discussed in terms of a two-dimensional decoupling.Comment: 5 pages including 4 figures in two columns, to appear in Phys. Rev. Let

    Momentum Distribution in the Decay B-->J/psi+X

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    We combine the NRQCD formalism for the inclusive color singlet and octet production of charmonium states with the parton and the ACCMM model, respectively, and calculate the momentum distribution in the decay B-->J/psi+X. Neglecting the kinematics of soft gluon radiation, we find that the motion of the b quark in the bound state can account, to a large extent, for the observed spectrum. The parton model gives a satisfactory presentation of the data, provided that the heavy quark momentum distribution is taken to be soft. To be explicit, we obtain epsilon_p=O(0.008-0.012) for the parameter of the Peterson et al. distribution function. The ACCMM model can account for the data more accurately. The preferred Fermi momentum p_F=O(0.57 GeV) is in good agreement with recent studies of the heavy quark's kinetic energy.Comment: revised version to be published in Phys. Rev. D; 27 pages, LaTeX, 7 eps figures, uses a4wide.sty, epsfig.sty and amssymb.st

    Adiabatic perturbations in pre big bang models: matching conditions and scale invariance

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    At low energy, the four-dimensional effective action of the ekpyrotic model of the universe is equivalent to a slightly modified version of the pre big bang model. We discuss cosmological perturbations in these models. In particular we address the issue of matching the perturbations from a collapsing to an expanding phase in full generality. We show that, generically, one obtains n=0n=0 for the spectrum of scalar perturbations in the original pre big model (with vanishing potential). When an exponential potential for the dilaton is included, a scale invariant spectrum (n=1n=1) of adiabatic scalar perturbations is produced under very generic matching conditions, both in a modified pre big bang and ekpyrotic scenario. We also derive general results valid for power law scale factors matched to a radiation dominated era.Comment: 11 pages, 1 figure, revised version with small corrections to match version in print. Results and conclusions unchange
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