Spitzer space telescope observations of SGR and AXP environments     

Stefanie Wachter  Chryssa Kouveliotou  Sandeep Patel  Don Figer  Peter Woods 《Astrophysics and Space Science》2007,308(1-4):67-71

Both Anomalous X-ray Pulsars (AXPs) and Soft Gamma Repeaters (SGRs) are thought to be manifestations of magnetars. However, the specific physical characteristics that differentiate the two classes of objects remain unclear. There is some evidence that the progenitors of these sources and/or the environment in which they form might influence the type of phenomena the resulting magnetar displays. Several of the AXPs appear to be associated with supernova remnants, while embedded clusters of massive stars have been found in the immediate vicinity of some SGRs. Since both AXPs and SGRs are distributed close to the Galactic plane, high extinction makes studies in the optical difficult. We present early results from our Spitzer program aimed at probing the environmental factors that might contribute to the difference in the observed characteristics between AXPs and SGRs.  相似文献   

Heat of formation of petalite, LiAlSi4O10     

D. W. Faßhauer  L. Cemič 《Physics and Chemistry of Minerals》2001,28(8):531-533

The enthalpy of formation of petalite, LiAlSi₄O₁₀, has been measured using high-temperature solution calorimetry. The measurements were carried out in a Calvet-type twin micro calorimeter at 728?°C. A 2PbO?·?B₂O₃ melt was used as a solvent. Tabulated heats of formation of the components and tabulated heat capacities of the reactants and the product (Robie and Hemingway 1995) were used to calculate the standard heat of formation of petalite from the measured heats of solution. The calculations yielded a mean value of Δ _f H ^pet _298.15=?4872±5.4 kJ mol^?1. This value may be compared to the heat of formation of Δ _f H ^pet _298.15= ?4886.5±6.3 kJ mol^?1 determined by the HF solution calorimetry by Bennington et?al. (1980). Faßhauer et?al. (1998) combined thermodynamic data with phase-equilibrium results to obtain best-fit thermodynamic results using the Bayes method, in order to derive an internally consistent dataset for phases in the NaAlSiO₄– LiAlSiO₄–Al₂O₃–SiO₂–H₂O system. They determined ?4865.6?±?0.8?kJ?mol^?1 as the enthalpy of formation of petalite, a value that is appreciably closer to the enthalpy found in this work.  相似文献   

Strahlungsmessungen als Hilfsmittel zur Diagnose atmosphärischer Zustände und Vorgänge     

H. Loßnitzer 《Theoretical and Applied Climatology》1954,6(1-2):91-112

Zusammenfassung An einem umfangreichen Beobachtungsmaterial besonders der zenitalen Himmelsstrahlung wird die Brauchbarkeit von Strahlungsmessungen mit verschiedenen Empfängern für die Überwachung atmosphärischer Trübungsverhältnisse und der Struktur der Trübung erprobt. Der Einfluß der selektiven Eigenschaften der einzelnen Empfängertypen auf die Meßvorgänge wird eingehend erörtert. Es wird gezeigt, daß Polarisations-und Farbwerte der zenitalen Himmelsstrahlung, die mit verhältnismäßig einfachen Mitteln (Selen-Photoelementen) gewonnen werden können, schon wesentliche Einblicke in den Trübungscharakter der Atmosphäre ermöglichen. Eine Verfeinerung der Analyse ist durch Intensitäts- und Polarisationsmessungen in engen Spektralbereichen, wie sie durch Verwendung von Interferenzfiltern in Verbindung mit Photomultipliern möglich sind, zu erreichen. Im Hinblick auf die noch unbefriedigende Bestimmung des Gesamtwasserdampfgehalts aus den atmosphärischen Absorptionsbanden bei durchgehender Strahlung wird auf die Möglichkeit, sie durch Messung der langwelligen Ausstrahlung zu kontrollieren und zu verbessern, hingewiesen.

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Summary On the basis of an extensive material of observations, in particular of zentithal sky radiation, the applicability of radiation measurements with different receivers for the control of atmospheric turbidity conditions and the structure of turbidity is investigated. The influence of the selective prpperties of the different receiver types on the measuring processes is discussed in detail. It is shown that polarisation and colour values of zenithal sky radiation obtainable by relatively simple means (selenium rectifier cells) give considerable insight into the character of atmospheric turbidity. An improvement of the analysis can be reached by measurements of intensity and polarisation within small spectral ranges such as are possible by applygin interference filters in combination with photomultipliers. With regard to the yet unsatisfactory determination of total water vapour contents from the atmospheric absorption bands of transmitted radiation the possibility is emphasized to control and improve it by measuring the outgoing long-wave radiation.

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Résumé Au moyen d'un riche matériel d'observations concernant surtout le rayonnement du ciel zénital on étudie la valeur de différents récepteurs en vue du contrôle du trouble atmosphérique et notamment de sa structure. On discute l'effet des propriétés sélectives des récepteurs sur lesprocédés des mesures. On montre que la polarisation et la couleur du rayonnement du ciel zénital mesurées par des moyens relativement simples (cellules au sélénium) fournissent déjà d'utiles renseignements sur le caractère du trouble atmosphérique. On arrive à améliorer les résultats par des mesures d'intensité et de polarisation à l'intérieur de régions spectrales étroites, ainsi que par l'emploi de filtres à interférences combinés avec des photomultiplicateurs. Considérant que la teneur totale en vapeur d'eau de l'atmosphère ne se détermine qu'imparfaitement par la transmission dans les bandes d'absorption, l'auteur évoque la possibilité de la déterminer par la mesure du rayonnement effectif à grande longueur d'onde.

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Mit 12 Textabbildungen.  相似文献   

Cytochrome P4501A expression,chemical contaminants and histopathology in roach,goby and sturgeon and chemical contaminants in sediments from the Caspian Sea,Lake Balkhash and the Ily River Delta,Kazakhstan   总被引：1，自引：0，他引：1  

Moore MJ  Mitrofanov IV  Valentini SS  Volkov VV  Kurbskiy AV  Zhimbey EN  Eglinton LB  Stegeman JJ 《Marine pollution bulletin》2003,46(1):107-119

Roach, goby and sturgeon were examined for cytochrome P4501A (CYP1A) expression and histopathology, in relation to contaminant burdens in fish and sediment. Gradients of induction of CYP1A were observed. Roach from the Ural and Ily River Deltas and roach and goby from the two stations nearest the Caspian Sea oil fields displayed higher levels of CYP1A expression in several organs than was observed in fish from further offshore. Great sturgeon and Russian sturgeon showed higher levels of CYP1A expression than was seen in starred sturgeon and gobies in the Ural delta. No fish showed evidence of contaminant-related histopathologies in the organs examined, despite the elevated CYP1A levels. Low levels of polychlorinated biphenyls and elevated levels of inshore and riverine petroleum hydrocarbons from these habitats suggest that this ongoing hydrocarbon exposure, and that from natural sources and long-term oil exploration on the Northeastern Caspian shore, contributed to the CYP1A induction observed.  相似文献   

Gene Expression Analysis for Exposure to Estrogenic Substances     

Martin Alberti  Ulf Kausch  Stefanie Haindl  Martin Seifert 《洁净——土壤、空气、水》2005,33(1):38-44

Zebrafish (Danio rerio) were exposed with 17β‐estradiol (E2) and nonylphenol (NP) in different concentrations. Gene expression analysis was carried out by two different approaches. First, RT‐PCR experiments were performed for the examination of expression levels of the two marker genes vitellogenin and aromatase. This approach showed a significant increase in the expression of the vitellogenin gene in exposed male fish (500 ng/L 17β‐estradiol and 250 μg/L nonylphenol). This egg yolk protein is usually not synthesized in male vertebrates. A slight decrease of expression of the aromatase gene was observed in exposed female zebrafish. Aromatase is known to catalyze the conversion of androgens to estrogens. Second, DNA microarray experiments were carried out, which allow the simultaneous examination of the expression levels of a great number of marker genes. The microarray experiments resulted in an up‐regulation of vitellogenin up to 850‐fold. In addition, several other genes were identified to be up‐regulated by estrogens, for example the high mobility group box protein ssrp1 (78‐fold) or the chaperonin containing t‐complex polypeptide 1, beta subunit cctb (22‐fold).  相似文献   

Mixing Ratios and Photostationary State of NO and NO2 Observed During the POPCORN Field Campaign at a Rural Site in Germany     

F. Rohrer  D. Brüning  E. S. Grobler  M. Weber  D. H. Ehhalt  R. Neubert  W. Schüßler  I. Levin 《Journal of Atmospheric Chemistry》1998,31(1-2):119-137

Ambient mixing ratios of NO, NO2, and O3 were determined together with the photolysis frequency of NO2, JNO2, at a rural, agricultural site in Germany. The data were collected during the POPCORN-campaign from August 1 to August 24, 1994, in a maize field 6 m above ground. The medians of the NO, NO2, and O3 mixing ratios between 10:00 and 14:00 UT were 0.25, 1.09, and 45 ppbv, respectively. The corresponding median of JNO2 was 6.0 · 10–3 s–1. NOx = NO + NO2 showed a strong diurnal variation with maximum mixing ratios at night, suggestive of a strong local surface source of NO, probably by microbial activity in the soil. The estimated average emission rate was 40 ng(N) m–2 s–1 of NOx, the major part of it probably in the form of NO. The available measurements allowed the estimation of the local NOx budget. At night the budget is almost closed and the measured NOx mixing ratios can be explained by the local source, local dry deposition of NO2, formation of NO3 and N2O5, and vertical exchange of air across the nocturnal inversion. During day-time, the local surface source of NO is not sufficient to explain the measured mixing ratios, and horizontal advection of NOx to the site must be included. The NO2/NO ratio during the morning und late afternoon is lower than predicted from the photostationary state owing to the local NO surface source, but is regulary higher during the hours around noon. For noon, August 10, 1994, the NO2/NO ratio was used to derive the momentary lower limit for the concentration of the peroxy-radicals of 2.2 · 109 cm–3 (86 pptv).  相似文献   

Reference Materials in Geoanalytical and Environmental Research ‐ Review for 2006 and 2007     

Klaus Peter Jochum  Stefanie M. Brueckner 《Geostandards and Geoanalytical Research》2008,32(4):405-452

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Climate change effects on hydrological system conditions influencing generation of storm runoff in small Alpine catchments   总被引：1，自引：0，他引：1       下载免费PDF全文

Gertraud Meißl  Herbert Formayer  Klaus Klebinder  Florian Kerl  Friedrich Schöberl  Clemens Geitner  Gerhard Markart  David Leidinger  Axel Bronstert 《水文研究》2017,31(6):1314-1330

Floods and debris flows in small Alpine torrent catchments (<10 km²) arise from a combination of critical antecedent system state conditions and mostly convective precipitation events with high precipitation intensities. Thus, climate change may influence the magnitude–frequency relationship of extreme events twofold: by a modification of the occurrence probabilities of critical hydrological system conditions and by a change of event precipitation characteristics. Three small Alpine catchments in different altitudes in Western Austria (Ruggbach, Brixenbach and Längentalbach catchment) were investigated by both field experiments and process‐based simulation. Rainfall–runoff model (HQsim) runs driven by localized climate scenarios (CNRM‐RM4.5/ARPEGE, MPI‐REMO/ECHAM5 and ICTP‐RegCM3/ECHAM5) were used in order to estimate future frequencies of stormflow triggering system state conditions. According to the differing altitudes of the study catchments, two effects of climate change on the hydrological systems can be observed. On one hand, the seasonal system state conditions of medium altitude catchments are most strongly affected by air temperature‐controlled processes such as the development of the winter snow cover as well as evapotranspiration. On the other hand, the unglaciated high‐altitude catchment is less sensitive to climate change‐induced shifts regarding days with critical antecedent soil moisture and desiccated litter layer due to its elevation‐related small proportion of sensitive areas. For the period 2071–2100, the number of days with critical antecedent soil moisture content will be significantly reduced to about 60% or even less in summer in all catchments. In contrast, the number of days with dried‐out litter layers causing hydrophobic effects will increase by up to 8%–11% of the days in the two lower altitude catchments. The intensity analyses of heavy precipitation events indicate a clear increase in rain intensities of up to 10%.  相似文献   

Annealing of far infrared photoconductors with infrared diode lasers     

U. Schießl  M. Tacke  J. Wolf  D. Lemke 《Experimental Astronomy》1991,2(3):139-148

High sensitivity infrared detectors made from extrinsic semiconductors are used for astronomical applications on satellite missions in the earth orbit. High energy radiation reduces the sensitivity and changes the calibration of these photoconductors drastically. This process is reversible through on board annealing. Laser emission of mid infrared diode lasers was used for efficient annealing with low power dissipation.  相似文献   

Über Wasserhosen auf dem Mittelmeer     

F. Roßmann 《Ocean Dynamics》1961,14(2):63-65

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