3,949 research outputs found

    Calibration of weak 1.4 and 1.9 mu water-vapor absorptions

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    Calibration of water absorption bands in near infrared regio

    Arizona-NASA Atlas of infrared solar spectrum, a preliminary report, number 123

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    Photometric tracings of infrared solar spectrum from NASA CV-990 jet during July-August 196

    Solar comparison spectra, 1.0-2.5 mu, from altitudes 1.5-12.5 km

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    Solar and telluric infrared spectra from altitudes between 1.5 and 12.5 k

    Pulsar spin-down: the glitch-dominated rotation of PSR J0537-6910

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    The young, fast-spinning, X-ray pulsar J0537-6910 displays an extreme glitch activity, with large spin-ups interrupting its decelerating rotation every ~100 days. We present nearly 13 years of timing data from this pulsar, obtained with the {\it Rossi X-ray Timing Explorer}. We discovered 22 new glitches and performed a consistent analysis of all 45 glitches detected in the complete data span. Our results corroborate the previously reported strong correlation between glitch spin-up size and the time to the next glitch, a relation that has not been observed so far in any other pulsar. The spin evolution is dominated by the glitches, which occur at a rate ~3.5 per year, and the post-glitch recoveries, which prevail the entire inter-glitch intervals. This distinctive behaviour provides invaluable insights into the physics of glitches. The observations can be explained with a multi-component model which accounts for the dynamics of the neutron superfluid present in the crust and core of neutron stars. We place limits on the moment of inertia of the component responsible for the spin-up and, ignoring differential rotation, the velocity difference it can sustain with the crust. Contrary to its rapid decrease between glitches, the spin-down rate increased over the 13 years, and we find the long-term braking index nl=1.22(4)n_{\rm l}=-1.22(4), the only negative braking index seen in a young pulsar. We briefly discuss the plausible interpretations of this result, which is in stark contrast to the predictions of standard models of pulsar spin-down.Comment: Minor changes to match the MNRAS accepted versio

    Partial Isometries of a Sub-Riemannian Manifold

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    In this paper, we obtain the following generalisation of isometric C1C^1-immersion theorem of Nash and Kuiper. Let MM be a smooth manifold of dimension mm and HH a rank kk subbundle of the tangent bundle TMTM with a Riemannian metric gHg_H. Then the pair (H,gH)(H,g_H) defines a sub-Riemannian structure on MM. We call a C1C^1-map f:(M,H,gH)(N,h)f:(M,H,g_H)\to (N,h) into a Riemannian manifold (N,h)(N,h) a {\em partial isometry} if the derivative map dfdf restricted to HH is isometric; in other words, fhH=gHf^*h|_H=g_H. The main result states that if dimN>k\dim N>k then a smooth HH-immersion f0:MNf_0:M\to N satisfying fhH<gHf^*h|_H<g_H can be homotoped to a partial isometry f:(M,gH)(N,h)f:(M,g_H)\to (N,h) which is C0C^0-close to f0f_0. In particular we prove that every sub-Riemannian manifold (M,H,gH)(M,H,g_H) admits a partial isometry in Rn\R^n provided nm+kn\geq m+k.Comment: 13 pages. This is a revised version of an earlier submission (minor revision

    A search for 183-GHz emission from water in late-type stars

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    A search was made for 183 GHz line emission from water vapor in the direction of twelve Mira and two semiregular variables. Upper limits to the emission are in the range of 2000 to 5000 Jy. It is estimated that thermal emission from the inner regions of late type stellar envelopes will be on the order of ten Jy. Maser emission, according to one model, would be an order of magnitude stronger. From the limited set sampled, the possibility of very strong maser emission at 183 GHz cannot yet be ruled out

    Gynodioecy in <i>Plantago lanceolata</i>:VI. Functions of cytokinins in growth, development, and reproduction of two sex types

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    Theoretical models predict that male sterile plants of gynodioecious species should show at least some compensation for their disadvantage of not reproducing as males through female component of fitness. In this study, growth, development, and reproduction of a hermaphrodite and a male sterile family of Plantago lanceolata L. were compared under controlled conditions. The male sterile plants produced more and longer spikes and had relatively longer styles. The male sterile plants achieved their final biomass sooner, by an earlier formation of side rosettes, and flowered earlier. The hypothesis was tested as to whether cytokinins in the plants are involved as a pleiotropic factor in either or both sex expression and the various plant characteristics associated with the male sterile phenotype. The roots of the male sterile plants had higher concentrations of putative zeatin riboside than the roots of the hermaphroditic plants, as quantified by an enzyme-linked immunoassy after separation of cytokinins by high performance liquid chromatography. Spraying the plants with benzyladenine did not affect internal cytokinin concentrations or sex expression. Benzyladenine spray increased the growth rate of the main rosette and stimulated floral initiation. Our results indicate that cytokinins are possibly involved in determining the morphological differences between sex types in this species

    183 GHz water line variation: An energetic outburst in orion KL

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    Observations of the 3(13)-2(20) transition of water vapor in the direction of Ori MC1 in 1980 February show a 50% flux increase and an apparent additional red shift of approximately 2 km/s relative to the line observed in 1977 December. From a detailed examination of the amplitude and frequency calibration, it appears unlikely that the effect is due to systematic error. The increase is attributed to the appearance of a new component at a velocity of 12 km/s with respect to the local standard of rest. The new component also has broad wings. Increased emission from a region in the high-velocity core of Ori MC1 can be due either to additional far-IR radiation to pump the 1983 GHz transition or to a change in the physical conditions in the gas. Statistical equilibrium calculations using the large-velocity-gradient formalism were carried out to develop a model for the emission. The calculations support a model in which the gas in the region of enhanced emission is hotter than the dust. The temporal coincidence between the 183 GHZ increase and the 22 GH1 water maser outburst suggests a common, impulsive cause, which has heated the gas in a part of the HV source, enhancing the emission in both transitions

    A high-resolution solar spectrometer for air-borne infrared observations, number 126

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    High resolution solar spectrometer for CV-990 aircraft infrared observation

    EU Agricultural Trade Relations with Asian countries

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