19,913 research outputs found

    Publications of the planetary biology program for 1976: A special bibliography

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    An annual listing of current publications resulting from research pursued under the auspices of NASA's Planetary Biology Program is presented. To stimulate the exchange of information and ideas among scientists working in the different areas of the program. To facilitate the exchange process. The author of each publication who is presently participating in the program is identified by asterisk. Current addresses for all principal investigators are given in the appendix

    Scientific publications and presentations relating to planetary quarantine. Volume 5: The 1971 supplement

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    A bibliographic compilation, with approximately 200 listings, on planetary quarantine is presented. Also given are scientific publications, and presentations along with an author index

    Scientific publications and presentations relating to planetary quarantine. Volume 5: The 1972 supplement

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    The sixth annual supplement to the bibliography on planetary quarantine contains 191 references, an author index and a permuted title index

    The Late Time Light Curve of SN 1998bw Associated with GRB980425

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    We report 139 photometric observations through the B, V, and I filters of the supernova SN 1998bw, an object which is associated with the Gamma-Ray Burst GRB 980425. Detailed light curves of this unique supernova can be compared to theoretical models, so we report here our light curve for 123 days between 27 June 1998 and 28 October 1998. The light curve of SN 1988bw is consistent with those of the Type Ic class. We find that the magnitude-versus-time relation for this supernova is linear to within 0.05 mags in all colors over the entire duration of our study. Our measured uniform decline rates are 0.0141±0.00020.0141 \pm 0.0002, 0.0184±0.00030.0184 \pm 0.0003, and 0.0181±0.00030.0181 \pm 0.0003 magnitudes per day in the B, V, and I bands. The linear decline and the rate of that decline suggest that late time light curve is powered by the radioactive decay of cobalt with some leakage of the gamma rays.Comment: 15 pages, 1 figure, 1 table, Accepted for publication in PAS

    Widely wavelength-selective Al2O3:Er3+ ring laser

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    Integrated Al2O3:Er3+ channel waveguide ring lasers were realized on thermally oxidized silicon substrates. High pump power coupling into- and low output power coupling from the ring is achieved in a straightforward design. Wavelength\ud selection in the range 1532 to 1557 nm was demonstrated by\ud varying the length of the output coupler from the ring

    Evidence for High-Frequency QPOs with a 3:2 Frequency Ratio from a 5000 Solar Mass Black Hole

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    Following the discovery of 3:2 resonance quasi-periodic oscillations (QPOs) in M82X-1 (Pasham et al. 2014), we have constructed power density spectra (PDS) of all 15 (sufficiently long) {\it XMM-Newton} observations of the ultraluminous X-ray source NGC1313X-1 (LXL_{X} \approx 2×\times1040^{40} erg/sec). We detect a strong QPO at a frequency of 0.29±\pm0.01 Hz in data obtained on 2012 December 16. Subsequent searching of all the remaining observations for a 3:2/2:3 frequency pair revealed a feature at 0.46±\pm0.02 Hz on 2003 Dec 13 (frequency ratio of 1.59±\pm0.09). The global significance of the 0.29 Hz feature considering all frequencies between 0.1 and 4 Hz is >> 3.5 σ\sigma. The significance of the 0.46±\pm0.02 Hz QPO is >> 3.5σ\sigma for a search at 2/3 and 3/2 of 0.29 Hz. We also detect lower frequency QPOs (32.9±\pm2.6 and 79.7±\pm1.2 mHz). All the QPOs are super-imposed on a continuum consisting of flat-topped, band-limited noise, breaking into a power-law at a frequency of 16±\pm3 mHz and white noise at \gtrsim 0.1 Hz. NGC1313X-1's PDS is analogous to stellar-mass black holes' (StMBHs) PDS in the so-called steep power-law state, but with the respective frequencies (both QPOs and break frequencies) scaled down by a factor of \sim 1000. Using the inverse mass-to-high-frequency QPO scaling of StMBHs, we estimate NGC1313X-1's black hole mass to be 5000±\pm1300 MM_{\odot}, consistent with an inference from the scaling of the break frequency. However, the implied Eddington ratio, LEdd_{Edd} >> 0.03±\pm0.01, is significantly lower compared to StMBHs in the steep power-law state (LEdd_{Edd} \gtrsim 0.2).Comment: Published in ApJ Letter

    Oil, Gas, and Mineral Law

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    Feasibility study of the transonic biplane concept for transport aircraft application

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    Investigations were conducted to evaluate the feasibility of a transonic biplane consisting of a forward-mounted swept-back lower wing, a rear-mounted swept-forward upper wing, and a vertical fin connecting the wings at their tips. This wing arrangement results in significant reductions in induced drag relative to a monoplane designed with the same span, and it allows for a constant-section fuselage shape while closely matching an ideal area distribution curve for M = 0.95 cruise. However, no significant reductions in ramp weight were achieved for the biplane relative to a monoplane with the same mission capability. Flutter analyses of the biplane revealed both symmetric and antisymmetric instabilities that occur well below the required flutter speed. Further studies will be required to determine if acceptable flutter speeds can be achieved through the elimination of the instabilities by passive means or by active controls. Configurations designed for other missions, especially those with lower Mach numbers and lower dynamic pressures, should be examined since the geometries suitable for those design constraints might avoid the weight penalties and flutter instabilities which prevent exploitation of induced drag benefits for the configuration studied

    A pp-adic RanSaC algorithm for stereo vision using Hensel lifting

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    A pp-adic variation of the Ran(dom) Sa(mple) C(onsensus) method for solving the relative pose problem in stereo vision is developped. From two 2-adically encoded images a random sample of five pairs of corresponding points is taken, and the equations for the essential matrix are solved by lifting solutions modulo 2 to the 2-adic integers. A recently devised pp-adic hierarchical classification algorithm imitating the known LBG quantisation method classifies the solutions for all the samples after having determined the number of clusters using the known intra-inter validity of clusterings. In the successful case, a cluster ranking will determine the cluster containing a 2-adic approximation to the "true" solution of the problem.Comment: 15 pages; typos removed, abstract changed, computation error remove

    Momentum distribution of confined bosons: temperature dependence

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    The momentum distribution function of a parabolically confined gas of bosons with harmonic interparticle interactions is derived. In the Bose-Einstein condensation region, this momentum distribution substantially deviates from a Maxwell-Boltzmann distribution. It is argued that the determination of the temperature of the boson gas from the Bose-Einstein momentum distribution function is more appropriate than the currently used fitting to the high momentum tail of the Maxwell-Boltzmann distribution.Comment: 5 REVTEX pages + 2 postscript figures. Accepted in Phys. Rev.
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