1,735 research outputs found

    Episode of unusual high solar ultraviolet radiation over central Europe due to dynamical reduced total ozone in May 2005

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    In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter called "ozone mini-hole" was caused by an elevation of tropopause height accompanied with a poleward advection of ozone-poor air from the tropics. The resultant increase in UV-radiation is of particular significance for human health. Dynamically induced low ozone episodes that happen in late spring can considerably enhance the solar UV-radiation in mid latitudes and therefore contribute to the UV-burden of people living in these regions

    Effects of Superconductivity and Charge Order on the sub-Terahertz reflectivity of La1.875_{1.875}Ba0.125−y_{0.125-y}Sry_{y}CuO4_4

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    The reflectivity R(ω)R (\omega) of both the abab plane and the c axis of two single crystals of La1.875_{1.875}Ba0.125−y_{0.125-y}Sry_{y}CuO4_4 has been measured down to 5 cm−1^{-1}, using coherent synchrotron radiation below 30 cm−1^{-1}. For yy = 0.085, a Josephson Plasma Resonance is detected at Tâ‰ȘTcT \ll T_c = 31 K in Rc(ω)R_{c} (\omega), and a far-infrared peak (FIP) appears in the optical conductivity below 50 K, where non-static charge ordering (CO) is reported by X-ray scattering. For yy = 0.05 (TcT_c = 10 K), a FIP is observed in the low-temperature tetragonal phase below the ordering temperature TCOT_{CO}. At 1/8 doping the peak frequency scales linearly with TCOT_{CO}, confirming that the FIP is an infrared signature of CO, either static or fluctuating.Comment: v2: longer version, 9 pages, 6 color figure

    Strong stability of 2D viscoelastic Poiseuille-type flows

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    We investigate Lp stability issues of small viscoelastic Poiseuilletype ows in two dimensions stemming from a model considered in Fang- Hua Lin, Chun Liu, and Ping Zhang (2005). We show local existence of perturbed ows of locally-in-time existing Poiseuille-type ows and global existence of the peturbed ows whenever the initial perturbation is small enough. In this case the perturbed ow decays exponentially. In all cases, the perturbations immediately regularize

    On the Stokes semigroup in some non-Helmholtz domains

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    This paper shows that Lp-Helmholtz decomposition is not necessary to establish the analyticity of the Stokes semigroup in C0; , the L 1 -closure of the space of all compactly supported smooth solenoidal vector fields. In fact, in a sector-like domain for which the Lp-Helmholtz decomposition does not hold, the analyticity of the Stokes semigroup in C0; is proved

    On the Stokes resolvent estimates for cylindrical domains

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    This paper studies the analyticity of the Stokes semigroup in an infinite cylinder or more generally a cylindrical domain with several exits to infinity in the space C0; , the L 1 -closure of all smooth compactly supported solenoidal vector fields. These domains are not strictly admissible in the sense of the first two authors (2014). However, it is shown that these domains are still admissible which yields the analyticity in C0; . A new proof based on a blow-up argument is given to derive an L 1 -type resolvent estimate which enables us to conclude that the analyticity angle of the Stokes semigroup in C0; is =2

    Catalog of Galaxy Morphology in Four Rich Clusters: Luminosity Evolution of Disk Galaxies at 0.33<z<0.83

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    Hubble Space Telescope (HST) imaging of four rich, X-ray luminous, galaxy clusters (0.33<z<0.83) is used to produce quantitative morphological measurements for galaxies in their fields. Catalogs of these measurements are presented for 1642 galaxies brighter than F814W(AB)=23.0 . Galaxy luminosity profiles are fitted with three models: exponential disk, de Vaucouleurs bulge, and a disk-plus-bulge hybrid model. The best fit is selected and produces a quantitative assessment of the morphology of each galaxy: the principal parameters derived being B/T, the ratio of bulge to total luminosity, the scale lengths and half-light radii, axial ratios, position angles and surface brightnesses of each component. Cluster membership is determined using a statistical correction for field galaxy contamination, and a mass normalization factor (mass within boundaries of the observed fields) is derived for each cluster. In the present paper, this catalog of measurements is used to investigate the luminosity evolution of disk galaxies in the rich-cluster environment. Examination of the relations between disk scale-length and central surface brightness suggests, under the assumption that these clusters represent a family who share a common evolutionary history and are simply observed at different ages, that there is a dramatic change in the properties of the small disks (h < 2 kpc). This change is best characterized as a change in surface brightness by about 1.5 magnitude between z=0.3 and z=0.8 with brighter disks at higher redshifts.Comment: 53 pages, including 13 figures and 7 tables. Accepted for publication in the Astrophysical Journal Supplement Serie

    Accuracy of computerized tomography in determining hepatic tumor size in patients receiving liver transplantation or resection

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    Computerized tomography (CT) of liver is used in oncologic practice for staging tumors, evaluating response to treatment, and screening patients for hepatic resection. Because of the impact of CT liver scan on major treatment decisions, it is important to assess its accuracy. Patients undergoing liver transplantation or resection provide a unique opportunity to test the accuracy of hepatic-imaging techniques by comparison of finding of preoperative CT scan with those at gross pathologic examination of resected specimens. Forty-one patients who had partial hepatic resection (34 patients) or liver transplantation (eight patients) for malignant (30 patients) or benign (11 patients) tumors were evaluable. Eight (47%) of 17 patients with primary malignant liver tumors, four (31%) of 13 patients with metastatic liver tumors, and two (20%) of 10 patients with benign liver tumors had tumor nodules in resected specimens that were not apparent on preoperative CT studies. These nodules varied in size from 0.1 to 1.6 cm. While 11 of 14 of these nodules were 1.0 cm. These results suggest that conventional CT alone may be insufficient to accurately determine the presence or absence of liver metastases, extent of liver involvement, or response of hepatic metastases to treatment

    Publizistische Stellvertretung. Kein Grund fĂŒr Angst vor Gemeinsamkeit in der Courage

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    K. Friedrich Schade, Leiter der ABP-Fachstelle "Medien" beim Evangelischen Pressedienst (epd) in Frankfurt, war verantwortlich fĂŒr den vierzehntĂ€glich erscheinenden Fachinformationsdienst epd-Entwicklungspolitik und die pĂ€dagogische Arbeitshilfe epd-Dritte Welt-Information. Schades EinschĂ€tzungen beziehen sich in diesem Artikel auf epd-Entwicklungspolitik. (DIPF/Orig.

    Hubble Space Telescope Imaging of the CFRS and LDSS Redshift Surveys---III. Field elliptical galaxies at 0.2 < z < 1.0

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    Surface photometry has been performed on a sample of 46 field elliptical galaxies. These galaxies are described well by a deVaucouleurs R^{1/4} profile. The sample was selected from the combined Canada-France and LDSS redshift surveys and spans the range 0.20 < z < 1.00. The relationship between galaxy half-light radius and luminosity evolves such that a galaxy of a given size is more luminous by Delta M_B=-0.97 \pm 0.14 mag at z=0.92 and the mean rest-frame color shifts blueward by Delta (U-V) =-0.68 \pm 0.11 at z=0.92 relative to the local cluster relations. Approximately 1/3 of these elliptical galaxies exhibit [OII] 3727 emission lines with equivalent widths > 15 angstroms indicating ongoing star formation. Estimated star-formation rates imply that \le 5% of the stellar mass in the elliptical galaxy population has been formed since z=1. We see no evidence for a decline in the space density of early-type galaxies with look-back time. The statistics and a comparison with local luminosity functions are both consistent with the view that the population of massive early-type galaxies was largely in place by z~1. This implies that merging is not required since that time to produce the present-day space density of elliptical galaxies.Comment: 21 pages plus 8 figures plus 5 tables. Accepted by Astrophysical Journa
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