3,129 research outputs found

    Approximation properties of the qq-sine bases

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    For q>12/11q>12/11 the eigenfunctions of the non-linear eigenvalue problem associated to the one-dimensional qq-Laplacian are known to form a Riesz basis of L2(0,1)L^2(0,1). We examine in this paper the approximation properties of this family of functions and its dual, in order to establish non-orthogonal spectral methods for the pp-Poisson boundary value problem and its corresponding parabolic time evolution initial value problem. The principal objective of our analysis is the determination of optimal values of qq for which the best approximation is achieved for a given pp problem.Comment: 20 pages, 11 figures and 2 tables. We have fixed a number of typos and added references. Changed the title to better reflect the conten

    A new blue-tailed Monitor lizard (Reptilia, Squamata, Varanus) of the Varanus indicus group from Mussau Island, Papua New Guinea

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    We describe a new species of Varanus from Mussau Island, north-east of New Guinea. The new species is a member of the Varanus indicus species group and is distinguished from all other members by both morphological and molecular genetic characters. It is the third species of Varanus reported from the Bismarck Archipelago and the first record of a yellow tongued member of the Varanus indicus species group from a remote oceanic island. The herpetofauna of Mussau Island has not been well studied but the discovery of this new species is in accordance with recent findings indicating that the island may harbor several unknown endemic vertebrates. The distribution of the closely related Varanus finschi is also discussed in the light of recent fieldwork and a review of old records.Valter Weijola, Stephen C. Donnellan, Christer Lindqvis

    The GOAL study: a prospective examination of the impact of factor V Leiden and ABO(H) blood groups on haemorrhagic and thrombotic pregnancy outcomes

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    Factor V Leiden (FVL) and ABO(H) blood groups are the common influences on haemostasis and retrospective studies have linked FVL with pregnancy complications. However, only one sizeable prospective examination has taken place. As a result, neither the impact of FVL in unselected subjects, any interaction with ABO(H) in pregnancy, nor the utility of screening for FVL is defined. A prospective study of 4250 unselected pregnancies was carried out. A venous thromboembolism (VTE) rate of 1·23/1000 was observed, but no significant association between FVL and pre-eclampsia, intra-uterine growth restriction or pregnancy loss was seen. No influence of FVL and/or ABO(H) on ante-natal bleeding or intra-partum or postpartum haemorrhage was observed. However, FVL was associated with birth-weights >90th centile [odds ratio (OR) 1·81; 95% confidence interval (CI<sub>95</sub>) 1·04–3·31] and neonatal death (OR 14·79; CI<sub>95</sub> 2·71–80·74). No association with ABO(H) alone, or any interaction between ABO(H) and FVL was observed. We neither confirmed the protective effect of FVL on pregnancy-related blood loss reported in previous smaller studies, nor did we find the increased risk of some vascular complications reported in retrospective studies

    Cold streams of ionospheric oxygen in the plasma sheet during the CDAW-6 event of March 22, 1979

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    During magnetospheric substorm events, the plasma and ion composition experiments in the ISEE-1 and 2 satellites detected cold ionospheric O+ streams, moving tailwards in the near Earth magnetotail. Flow is parallel to the magnetic field lines, with drift velocity in agreement with the electric field topology obtained by mapping the model ionospheric field along the magnetic field lines. Fluctuations of the flow velocity of the streams can be related to magnetotail movements. Oscillations of the flow direction and speed with periods ranging from 5 to 10 min that suggest the presence of waves are observed. The streams are observed at all distances between 15 and 6 Re from the Earth. When averaged over 360 deg, the streams show up as a low energy peak, superimposed on the distribution of isotropic plasma sheet ions. This double-peak structure of the energy spectrum seems typical of the disturbed plasma sheet

    Dissection Technique for Cochleas Prepared for Scanning Electron Microscopy

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    Scanning electron microscopy (SEM) permits a three-dimensional study of the surface morphology of the organ of Corti that is very useful in evaluating the condition of the apical end of the hair cells and the stereocilia. However, some laboratories have experienced problems with curling of the basilar membrane during critical point drying of cochlear specimens prepared For SEM evaluation using the Murakami or osmium thiocarbohydrazide-procedures. This curling of the basilar membrane can obstruct the view of the reticular lamina and the ciliary ends of the hair cells. We have used a dissection method, referred to as the anchor technique, to overcome basilar membrane curling. This technique removes all the structures above the reticular lamina but leaves the basilar membrane attached to the spiral ligament and the lateral bone to which the spiral ligament is anchored. Individual cochlear turns are dissected in this manner and mounted on the same examination stub For SEM evaluation. Maintenance of the lateral attachment of the basilar membrane requires additional dissection time but eliminates the problem of curling during critical point drying. An additional benefit is that mounting the individual turns on the same examination stub Facilitates evaluation and photomicroscopy of the surface morphology. The anchor technique has been used successfully on the guinea pig and should be appropriate for most mammalian cochleas

    Quantitative Evaluation of Scanning Electron Microscopy-Examined Ciliary Morphological Changes in Control and Noise Exposed Guinea Pig Cochleas

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    Many investigations of noise-induced hearing loss have demonstrated a poor correlation between hearing threshold and hair cell loss. One reason for this is that more subtle changes in the hair cell, such as detailed morphological changes of stereocilia, have not been evaluated. However, examining such changes increases the problem of distinguishing experimental pathological changes from artefacts. Preparation of the specimen for scanning electron microscopy (SEM) may result in too many artefacts for an adequate quantification of defects due to noise exposure. One problem with some earlier studies seems to be lack of controls and/or statistical analysis for the purpose of eliminating the influence of artefacts and spontaneous degeneration. The aim of this study was to compare unexposed and noise-exposed cochleas examined with SEM in order to determine if subtle changes due to noise could be distinguished from preparation artefacts and from spontaneous deterioration. Ten different types of hair cell changes were found in exposed and control animals. By means of using controls for statistical comparison with noise-exposed animals two cell damage categories hair cell loss and missing stereocilia were found to be produced by exposure to noise

    Indlæg angaaende den ondartede Lungesyges Optræden i Danmark.

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    Indlæg angaaende den ondartede Lungesyges Optræden i Danmark

    The slope of the black-hole mass versus velocity dispersion correlation

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    Observations of nearby galaxies reveal a strong correlation between the mass of the central dark object M and the velocity dispersion sigma of the host galaxy, of the form log(M/M_sun) = a + b*log(sigma/sigma_0); however, published estimates of the slope b span a wide range (3.75 to 5.3). Merritt & Ferrarese have argued that low slopes (<4) arise because of neglect of random measurement errors in the dispersions and an incorrect choice for the dispersion of the Milky Way Galaxy. We show that these explanations account for at most a small part of the slope range. Instead, the range of slopes arises mostly because of systematic differences in the velocity dispersions used by different groups for the same galaxies. The origin of these differences remains unclear, but we suggest that one significant component of the difference results from Ferrarese & Merritt's extrapolation of central velocity dispersions to r_e/8 (r_e is the effective radius) using an empirical formula. Another component may arise from dispersion-dependent systematic errors in the measurements. A new determination of the slope using 31 galaxies yields b=4.02 +/- 0.32, a=8.13 +/- 0.06, for sigma_0=200 km/s. The M-sigma relation has an intrinsic dispersion in log M that is no larger than 0.3 dex. In an Appendix, we present a simple model for the velocity-dispersion profile of the Galactic bulge.Comment: 37 pages, 9 figure

    Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES-13.

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    Observations from Magnetospheric MultiScale (~8 Re) and Van Allen Probes (~5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double-peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated E × B flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by Magnetospheric MultiScale (MMS), with a speed that is comparable to the E × B flow. The magnetopause speed and the E × B speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES-13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF waves also were seen. These observations demonstrate that even very weak shocks can have significant impact on the radiation belts
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