101 research outputs found

    Adaptation of The Doubly Labeled Water Method for Subjects Consuming Isotopically Enriched Water

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    The use of doubly labeled water (DLW) to measure energy expenditure is subject to error if the background abundance of the oxygen and hydrogen isotope tracers changes during the test period. This study evaluated the accuracy and precision of different methods by which such background isotope changes can be corrected, including a modified method that allows prediction of the baseline that would be achieved if subjects were to consume water from a given source indefinitely. Subjects in this study were eight women (4 test subjects and 4 control subjects) who consumed for 28 days water enriched to resemble drinking water aboard the United States space shuttle. Test subjects and control subjects were given a DLW dose on days 1 and 15, respectively. The change to an enriched water source produced a bias in expenditure calculations that exceeded 2.9 MJ/day (35%), relative to calculations from intake-balance. The proposed correction based on the predicted final abundance of 18O and deuterium after equilibration to the new water source eliminated this bias, as did the traditional use of a control group. This new modified correction method is advantageous under field conditions when subject numbers are limited

    Prospectus, May 19, 1975

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    MCMULLEN WINS PRESIDENCY; PC News….In Brief: Library Extends Hours, Registration By Mail Deadline May 27, New Officers For Chi Gamma; StuGo Budget Vetoed; VP Race Squeaker; Betty Furness To Address Grads; Dental Students Capped; Statutory Rape: Crime Without A Victim; StuGo Minutes; More StuGo Minutes; Fine Arts Week At Parkland; $9000...Where Does The Priority Lie?; The Kaleidoscope; The Short Circuit; letters; L.T.D.s Corner: OFF Without A Hitch...Almost; To The 1975 College Grads; Parkland: The Year In Review; Le Finis; Skylines; Chess Talk: Chess Notation; Congratulations to Mrs. Teresa Wells...; It\u27s Not Too Late For A Summer Job In Europe; Cimmeron Brings Insane Happiness; Suggestion Box; Wiechman Recieves ROTC Scholarship; What If...; Movie Revue: \u27Shampoo\u27; May 22nd: \u27Slink Rand\u27; Zappa Captivates Chicago; My Friendly Tree; Wanted: Reporters; Student Elections: Opinion Poll; S.I.U. Has New LibTech Program; Fine Arts Week; Classified Ads; Outside Life At PC; NROTC Scholarship Pgrogram; New Record For Bike Race; Sports Views; Trackmen Third In State; Cobras\u27 Win Streak Broken; Final Examination Schedule; Problems? Learning Lab Can Help; New Pharmacology Class; Awards Given At IOC Banquethttps://spark.parkland.edu/prospectus_1975/1009/thumbnail.jp

    The thermal emission of the exoplanets WASP-1b and WASP-2b

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    We present a comparative study of the thermal emission of the transiting exoplanets WASP-1b and WASP-2b using the Spitzer Space Telescope. The two planets have very similar masses but suffer different levels of irradiation and are predicted to fall either side of a sharp transition between planets with and without hot stratospheres. WASP-1b is one of the most highly irradiated planets studied to date. We measure planet/star contrast ratios in all four of the IRAC bands for both planets (3.6-8.0um), and our results indicate the presence of a strong temperature inversion in the atmosphere of WASP-1b, particularly apparent at 8um, and no inversion in WASP-2b. In both cases the measured eclipse depths favor models in which incident energy is not redistributed efficiently from the day side to the night side of the planet. We fit the Spitzer light curves simultaneously with the best available radial velocity curves and transit photometry in order to provide updated measurements of system parameters. We do not find significant eccentricity in the orbit of either planet, suggesting that the inflated radius of WASP-1b is unlikely to be the result of tidal heating. Finally, by plotting ratios of secondary eclipse depths at 8um and 4.5um against irradiation for all available planets, we find evidence for a sharp transition in the emission spectra of hot Jupiters at an irradiation level of 2 x 10^9 erg/s/cm^2. We suggest this transition may be due to the presence of TiO in the upper atmospheres of the most strongly irradiated hot Jupiters.Comment: 10 pages, submitted to Ap

    Phosphorylation by Akt within the ST loop of AMPK-α1 down-regulates its activation in tumour cells

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    The insulin/IGF-1 (insulin-like growth factor 1)-activated protein kinase Akt (also known as protein kinase B) phosphorylates Ser(487) in the ‘ST loop’ (serine/threonine-rich loop) within the C-terminal domain of AMPK-α1 (AMP-activated protein kinase-α1), leading to inhibition of phosphorylation by upstream kinases at the activating site, Thr(172). Surprisingly, the equivalent site on AMPK-α2, Ser(491), is not an Akt target and is modified instead by autophosphorylation. Stimulation of HEK (human embryonic kidney)-293 cells with IGF-1 caused reduced subsequent Thr(172) phosphorylation and activation of AMPK-α1 in response to the activator A769662 and the Ca(2+) ionophore A23187, effects we show to be dependent on Akt activation and Ser(487) phosphorylation. Consistent with this, in three PTEN (phosphatase and tensin homologue deleted on chromosome 10)-null tumour cell lines (in which the lipid phosphatase PTEN that normally restrains the Akt pathway is absent and Akt is thus hyperactivated), AMPK was resistant to activation by A769662. However, full AMPK activation could be restored by pharmacological inhibition of Akt, or by re-expression of active PTEN. We also show that inhibition of Thr(172) phosphorylation is due to interaction of the phosphorylated ST loop with basic side chains within the αC-helix of the kinase domain. Our findings reveal that a previously unrecognized effect of hyperactivation of Akt in tumour cells is to restrain activation of the LKB1 (liver kinase B1)–AMPK pathway, which would otherwise inhibit cell growth and proliferation

    KELT-1b: A Strongly Irradiated, Highly Inflated, Short Period, 27 Jupiter-mass Companion Transiting a mid-F Star

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    We present the discovery of KELT-1b, the first transiting low-mass companion from the wide-field Kilodegree Extremely Little Telescope-North (KELT-North) survey. The V=10.7 primary is a mildly evolved, solar-metallicity, mid-F star. The companion is a low-mass brown dwarf or super-massive planet with mass of 27.23+/-0.50 MJ and radius of 1.110+0.037-0.024 RJ, on a very short period (P=1.21750007) circular orbit. KELT-1b receives a large amount of stellar insolation, with an equilibrium temperature assuming zero albedo and perfect redistribution of 2422 K. Upper limits on the secondary eclipse depth indicate that either the companion must have a non-zero albedo, or it must experience some energy redistribution. Comparison with standard evolutionary models for brown dwarfs suggests that the radius of KELT-1b is significantly inflated. Adaptive optics imaging reveals a candidate stellar companion to KELT-1, which is consistent with an M dwarf if bound. The projected spin-orbit alignment angle is consistent with zero stellar obliquity, and the vsini of the primary is consistent with tidal synchronization. Given the extreme parameters of the KELT-1 system, we expect it to provide an important testbed for theories of the emplacement and evolution of short-period companions, and theories of tidal dissipation and irradiated brown dwarf atmospheres.Comment: 30 pages, 19 figures. Submitted to Ap

    KELT-2Ab: A Hot Jupiter Transiting the Bright (V=8.77) Primary Star of a Binary System

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    We report the discovery of KELT-2Ab, a hot Jupiter transiting the bright (V=8.77) primary star of the HD 42176 binary system. The host is a slightly evolved late F-star likely in the very short-lived "blue-hook" stage of evolution, with \teff=6148\pm48{\rm K}, logg=4.0300.026+0.015\log{g}=4.030_{-0.026}^{+0.015} and \feh=0.034\pm0.78. The inferred stellar mass is M=1.3140.060+0.063M_*=1.314_{-0.060}^{+0.063}\msun\ and the star has a relatively large radius of R=1.8360.046+0.066R_*=1.836_{-0.046}^{+0.066}\rsun. The planet is a typical hot Jupiter with period 4.11379±0.000014.11379\pm0.00001 days and a mass of MP=1.524±0.088M_P=1.524\pm0.088\mj\ and radius of RP=1.2900.050+0.064R_P=1.290_{-0.050}^{+0.064}\rj. This is mildly inflated as compared to models of irradiated giant planets at the \sim4 Gyr age of the system. KELT-2A is the third brightest star with a transiting planet identified by ground-based transit surveys, and the ninth brightest star overall with a transiting planet. KELT-2Ab's mass and radius are unique among the subset of planets with V<9V<9 host stars, and therefore increases the diversity of bright benchmark systems. We also measure the relative motion of KELT-2A and -2B over a baseline of 38 years, robustly demonstrating for the first time that the stars are bound. This allows us to infer that KELT-2B is an early K-dwarf. We hypothesize that through the eccentric Kozai mechanism KELT-2B may have emplaced KELT-2Ab in its current orbit. This scenario is potentially testable with Rossiter-McLaughlin measurements, which should have an amplitude of \sim44 m s1^{-1}.Comment: 9 pages, 2 tables, 4 figures. A short video describing this paper is available at http://www.youtube.com/watch?v=wVS8lnkXXlE. Revised to reflect the ApJL version. Note that figure 4 is not in the ApJL versio

    2-Mercapto-Quinazolinones as Inhibitors of Type II NADH Dehydrogenase and Mycobacterium tuberculosis:Structure-Activity Relationships, Mechanism of Action and Absorption, Distribution, Metabolism, and Excretion Characterization

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    <i>Mycobacterium tuberculosis</i> (<i>MTb</i>) possesses two nonproton pumping type II NADH dehydrogenase (NDH-2) enzymes which are predicted to be jointly essential for respiratory metabolism. Furthermore, the structure of a closely related bacterial NDH-2 has been reported recently, allowing for the structure-based design of small-molecule inhibitors. Herein, we disclose <i>MTb</i> whole-cell structure–activity relationships (SARs) for a series of 2-mercapto-quinazolinones which target the <i>ndh</i> encoded NDH-2 with nanomolar potencies. The compounds were inactivated by glutathione-dependent adduct formation as well as quinazolinone oxidation in microsomes. Pharmacokinetic studies demonstrated modest bioavailability and compound exposures. Resistance to the compounds in <i>MTb</i> was conferred by promoter mutations in the alternative nonessential NDH-2 encoded by <i>ndhA</i> in <i>MTb</i>. Bioenergetic analyses revealed a decrease in oxygen consumption rates in response to inhibitor in cells in which membrane potential was uncoupled from ATP production, while inverted membrane vesicles showed mercapto-quinazolinone-dependent inhibition of ATP production when NADH was the electron donor to the respiratory chain. Enzyme kinetic studies further demonstrated noncompetitive inhibition, suggesting binding of this scaffold to an allosteric site. In summary, while the initial <i>MTb</i> SAR showed limited improvement in potency, these results, combined with structural information on the bacterial protein, will aid in the future discovery of new and improved NDH-2 inhibitors
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