Refractive Focusing by Interstellar Clouds and the Rapid Polarization Angle Swing in QSO 1150＋812     

G. Cimò 《中国天文和天体物理学报》2006,6(1):1-14

A very rapid polarization position angle swing of～180°(with a time scale of～6 hours)observed at 2cm in QSO 1150+812(z=1.25)was reported by Kochenov & Gabuzda.This very rare event is difficult to explain.We found a pos- sible interpretation in the framework of a source model consisting of three polarized components,in which two compact polarized components are nearly simultaneously occulted by an interstellar cloud,with consequent focusing-defocusing effects.A spe- cific plasma-lens model is proposed which can reasonably fit the polarized flux density curve with results derived for the two lensed components.Some physical parameters of the plasma-lens and the source components are estimated.The two compact po- larized components are estimated to have brightness temperatures of～6×10~(12)K. Thus a bulk relativistic motion with a Lorentz factor less than 10 is required to meet the inverse-Compton limit.  相似文献   

Kinematics of a deep-seated landslide derived from photogrammetric, GPS and geophysical data   总被引：2，自引：0，他引：2  

E. Brückl  F.K. Brunner  K. Kraus 《Engineering Geology》2006,88(3-4):149-159

The deep-seated landslide located at the intersection of the Gradenbach and Möll valleys near Döllach, Austria, has been the target of many previous investigations [Kronfellner-Kraus, G., 1980. Neue Untersuchungsergebnisse in Wildbächen — Der Talzuschub in Abhängigkeit von Niederschlägen. Int. Symp. Interpraevent Bad Ischl 1: 179–192; Weidner, S., Moser, M., Lang, E., 1998. Influence of hydrology on sagging of mountain slopes (“Talzuschübe”) — New results of time series analysis. 8th International IAEG Congress, Vancouver, Canada, Balkema, Rotterdam, 1259–1266; Weidner, S., 2000. Kinematik und Mechanismus tiefgreifender alpiner Hangdeformationen unter besonderer Berücksichtigung der hydrologischen Verhältnisse. Dissertation, Friedrich–Alexander-Universität Erlangen–Nürnberg, 246.]. In this paper, photogrammetric, GPS and geophysical data have been utilized to derive a constraint on the kinematics of the sagging process. The photogrammetric models have been based on aerial photographs from 1962 and 1996. Displacement vectors of about 50 individual characteristic points have been determined; these clearly show the area of the sagging slope. From 1999 to 2004, eleven GPS campaigns have been carried out, yielding very accurate displacement vectors at four monitoring points. Information about the internal structure of the slope was determined using seismic surveys.

The displacements observed by photogrammetry and GPS have shown a rather uniform movement of the whole sagging slope, with a slight longitudinal compression of 0.6%. In order to extend the kinematic consideration to 3D, a special form of the equation of continuity (conservation of mass) has been applied to the 1962–1996 photogrammetric data, together with the cross-sections derived from the seismic data. The average velocities through cross-sections have been calculated by integrals of the mass-balance above and below these cross-sections. Changes of the total rock mass, due to accumulation and especially to erosion, as well as an overall compaction of 1.5% between 1962 and 1996, have been considered. The calculated average velocities through a cross-section and the surface velocities independently determined by photogrammetry agree within an uncertainty of 15%. The results indicate a block movement with shear concentration at the basal sliding surface.  相似文献   

Distribution, condition, and growth of newly settled southern flounder (Paralichthys lethostigma) in the Galveston Bay Estuary, TX     

Lindsay A. Glass  Jay R. Rooker  Richard T. Kraus  G. Joan Holt 《Journal of Sea Research》2008,59(4):259-268

Several flatfish species, including southern flounder (Paralichthys lethostigma) recruit to estuaries during early life. Therefore, evaluation of estuarine sites and habitats that serve as nurseries is critical to conservation and management. The present study used density data in conjunction with biochemical condition and growth measurements to evaluate settlement sites used by southern flounder in the Galveston Bay Estuary (GBE). In 2005, beam-trawl collections were made in three major sections of the GBE (East Bay, Galveston Bay, West Bay). Three sites were sampled in each bay. Within each sampling site, replicate collections were taken from three habitats: 1) marsh edge (< 1 m depth), 2) intermediate zone (10–20 m from marsh interface;  1 m depth), and 3) bay zone (typically > 100 m from marsh interface; depth > 1 m). Average size of southern flounder collected was 12–19 mm standard length, and peak densities occurred in January and February. Catch data indicated that densities of southern flounder were significantly greater in East Bay (2.75 per 100 m²) than in Galveston Bay (0.91 per 100 m²) or in West Bay (0.45 per 100 m²). Densities were statistically similar among habitats. Otolith-based estimates of age indicated that the majority of southern flounder collected were 35–45 days old and derived from early December to early January hatch-dates. Growth rates were similar among bays and among habitats, with the average growth rate being 0.40 mm day^− 1 (range: 0.21–0.76 mm day^− 1). RNA:DNA was above the established baseline value for nutritional stress, indicating that newly settled southern flounder in the GBE were in relatively high condition. Habitat-specific differences in RNA:DNA ratios were not observed; however, ratios were significantly lower in West Bay (average 8.0) than in East Bay (average 9.5) or in Galveston Bay (average 9.8), suggesting the condition of new recruits may vary spatially within the GBE. Findings from the current study suggest density and condition of newly settled southern flounder vary at the bay scale, suggesting that parts of GBE do not function equally as nurseries.  相似文献   

The emplacement of Variscan HT metamorphic rocks linked to the interaction between Gondwana and Laurussia: structural constraints in NE Sardinia (Italy)     

Franco Marco Elter  Matteo Padovano  Rita Katharina Kraus 《地学学报》2010,22(5):369-377

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Das Wachstum der Kontinente nach der Zyklustheorie     

E. Kraus 《International Journal of Earth Sciences》1928,19(6):481-493

Ohne Zusammenfassung  相似文献   

An analytical exericise to elucidate quasi-geostrophic frontogenesis     

Dipl.-Met. C. M. Ewenz  Prof. Dr. H. Kraus 《Meteorology and Atmospheric Physics》1990,42(3-4):179-196

Summary Frontogenesis is frequently described by theQ-vector (Hoskins et al., 1978), a term being composed of several derivatives of basic meteorological parameters and their products. Its distribution and especially the _H ·Q-fields are highly important to estimate frontogenesis and cross frontal circulation. Although theQ-vector (Hoskins et al., 1978) allows an easier assessment of the vertical wind forcing than the original omega equation of the quasi-geostrophic theory, it is still difficul to imagine the three-dimensional (3-d) spatial distribution ofQ and _H ·Q even for standard atmospheric fields. Thus there is a need to shed more light in theQ and _H ·Q-fields for special synoptic situations.This is done here by constructing analytical 3-d geostrophically balanced wind-and temperature fields, for which theQ-forcing (Qformed with the geostrophic wind) can easily be computed and presented. Three examples (see Sections 3 to 5) are discussed yielding typical and realistic (compared to known pattern) 3-d forcing distributions ofQ and _H ·Q. Within the simple analytical scheme used here their origin can casily be understood. These fields of a 2000×2000 km² horizontal domain ranging up to 250 hPa are: A modified Bergeron deformation field containing a cold front (case I a) and a warm front (case I b); an upper tropospheric jet including a jet-parallel transition zone between warm and cold air (case II); and a circular low pressure circulation pattern with two fronts (case III).The paper presents these 3-d fields with the advantage that the analytical method is not affected by any kind of limited numerical resolution. It also shows how these fields degenerate with decreasing resolution if the analytical data are used in descrete form. This simulates working with discrete numerical data and demonstrates how narrow frontal zones of structure elements ofQ and _H ·Q considerably smooth out with increasing grid distances.With 17 Figures  相似文献   

A New LA‐ICP‐MS Method for Ti in Quartz: Implications and Application to High Pressure Rutile‐Quartz Veins from the Czech Erzgebirge          下载免费PDF全文

Alicia M. Cruz‐Uribe  Regina Mertz‐Kraus  Thomas Zack  Maureen D. Feineman  Glenn Woods  Dorrit E. Jacob 《Geostandards and Geoanalytical Research》2017,41(1):29-40

Experimental determination of the pressure and temperature controls on Ti solubility in quartz provides a calibration of the Ti‐in‐quartz (TitaniQ) geothermometer applicable to geological conditions up to ~ 20 kbar. We present a new method for determining ⁴⁸Ti mass fractions in quartz by LA‐ICP‐MS at the 1 μg g^?1 level, relevant to quartz in HP‐LT terranes. We suggest that natural quartz such as the low‐CL rims of the Bishop Tuff quartz (determined by EPMA; 41 ± 2 μg g^?1 Ti, 2s) is more suitable than NIST reference glasses as a reference material for low Ti mass fractions because matrix effects are limited, Ca isobaric interferences are avoided, and polyatomic interferences at mass 48 are insignificant, thus allowing for the use of ⁴⁸Ti as a normalising mass. Average titanium mass fraction from thirty‐three analyses of low temperature quartz from the Czech Erzgebirge is 0.9 ± 0.2 μg g^?1 (2s) using ⁴⁸Ti as a normalising mass and Bishop Tuff quartz rims as a reference material. The 2s average analytical uncertainty for individual analyses of ⁴⁸Ti is 8% for 50 μm spots and 7% for 100 μm spots, which offers much greater accuracy than the 21–41% uncertainty (2s) incurred from using ⁴⁹Ti as an analyte.  相似文献   

Periodic Variations of the Jet Flow Lorentz Factor in 3C 273     

Shan-Jie Qian  Xi-Zhen Zhang  T. P. Krichbaum  J. A. Zensus  A. Witzel  A. Kraus  S. Britzen  H. Ungerechts  U. Lisenfeld 《中国天文和天体物理学报》2001,1(3):236-244

1 INTRODUCTIONThe quasar 3C 273 (z = 0.158) is one of the classical rwho sources showal apparellt superltalnal motion (Zensus et al. 1990, 1997). It has a large-scale jet (~ 20n of length, 3C273A)elliltting at radio, optical and X-ray bands. It has been suggested that its compel source(3C 273B) is a rmm-blazar, Undergoing strong and rapid Variations in ratio, optical-UV, X-rayand 7-my bands at various tab scales (from hours to years, Courvoisier et al. 1998, Tet al. 1999, Stevens et …  相似文献   

An individual-component approximation to quadratic stress for flow-decomposition analysis     

Adele Militello  Nicholas C. Kraus 《Ocean Engineering》1999,26(11):1039

An individual-component approximation (ICA) to the one-dimensional quadratic stress is presented for analysis of hydrodynamic systems that contain multiple-frequency fluid motion such as tidal current and nearshore currents. Criteria governing development of the approximation are accuracy, symmetry, and preservation of contributions (magnitude and direction) of individual and coupled velocity components. Preservation of directionality is required to isolate functioning of individual terms for flow-decomposition analysis. The ICA is compared with the small-amplitude approximation analytically and through numerical examination for two velocity components. The two approximations differ at second order within the range of validity of the small-amplitude approximation. The ICA is exact in the limits of components with large magnitudes and components of equal magnitudes. Based on calculations comparing the exact numerical solution for velocity components with a wide range of relative magnitudes, relative periods, and phase differences, the ICA is accurate except in restricted regions of small-magnitude quadratic velocity. The ICA is generalized to multiple components without restriction on magnitude, period, or phase, and example calculations are given for flows comprised of three components and six components. The method is applied to velocity tidal constituents for Galveston Bay, Texas, and Tampa Bay, Florida.  相似文献