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  • 1
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Zur Ermittlung des nicht-stationären Wärmeund Stoffübergangs bei natürlicher Konvektion in einem porösen Medium wurde eine eingehende numerische Untersuchung aufgestellt. Die das Problem bestimmenden Hauptkennzahlen sind:Ra,N,Le, Φ undAr. Insbesondere werden Resultate mitgeteilt, die die Einflüsse der kombinierten thermischen und konzentrationsbedingten Auftriebskräfte auf die zeitliche Entwicklung der örtlichen und gemittelten Nusselt- und Sherwood-Zahlen erkennen lassen. Diese zeigen, daß bei ansteigender Rayleigh-Zahl der Wärme- und Stoffübergang infolge größeren Auftriebseffektes erhöht wird. Zusätzlich führt der Anstieg des AuftriebsverhältnissesN zu einer Verbesserung der Wärme- und Stoffübergangsverhältnisse und bewirkt gleichzeitig eine Verkürzung der Zeitspanne, welche der Strömungsvorgang zur Annäherung an den stationären Zustand benötigt.
    Notes: Abstract A detailed numerical study has been performed to investigate transient natural convection heat and mass transfer in a porous enclosure. Major dimensionless groups governing the present problem areRa,N,Le, φ andAr. Results are particular presented to illustrate the effects of the combined thermal and solutal buoyancy forces on the temporal evolution of local/average Nusselt and Sherwood numbers. The results show that with the increase in the Rayleigh number, the heat and mass transfer is enhanced as a result of greater buoyancy effect. Additionally, the increase in buoyancy ratioN results in an improvement in the heat and mass transfer rates and in the mean time causes a short time duration for the flow to approach the steady-state condition.
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  • 2
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Alopecia areata (AA) is hypothesized to be an organ-specific autoimmune disease with genetic predisposition and an environmental trigger. There are few clinical data in Asians.Objectives  To describe the genetic epidemiological features of AA patients in China and to determine the possible genetic model for AA.Methods  Data for 1032 patients with AA were obtained by questionnaire in the Institute of Dermatology of Anhui Medical University in China from 2001 to 2003. Complex segregation analysis and heritability analysis were performed using Falconer's method, EPI INFO 6·0 and SAGE-REGTL programs.Results  In total, 1032 AA patients (male/female ratio 1·1 : 1) were enrolled, representing 0·94% of the total number of cases seen in our outpatient clinic during that time. The mean ± SD age of onset was 28·98 ± 13·43 years. The difference between the mean age of onset in males and females was not significant. Most patients (82·6%) experienced their first episode of AA within the first four decades of life. A positive family history of AA was obtained in 87 patients (8·4%). The prevalence of AA in first-, second- and third-degree relatives of the proband with AA was 1·6%, 0·19% and 0·03%, respectively. These figures were higher than those in controls. A greater severity and longer duration of AA were seen in the early onset group than in the late-onset group. The early onset group also had more affected first- and second-degree relatives. The heritability of AA in first-, second- and third-degree relatives was 47·16%, 42·53% and 22·29%, respectively. Based on the REGTL results, the best model was a polygenic additive model for AA.Conclusions  The effect of genetic factors is strong in AA, but environmental factors such as infection and psychological stress may still play an important role. Our findings on the genetics of AA are consistent with a polygenic additive mode of inheritance.
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  • 3
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
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  • 4
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The ideal noninteracting Bose gases trapped in a generic power-law potential in an any-dimensional space are studied. We present theoretical results of the corrections of thermodynamic properties due to finite particle number effects. The calculation uses the Euler-Maclaurin approximation to simplify the condensate fraction, and it also uses the Maslov index to discuss the boundary effect. Recently BEC (Bose-Einstein Condensation) has also been observed in a microelectronic chip; therefore, with a similar microstructure, we can obtain the effects of a rigid wall in a trap that have never been found before.
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  • 5
    ISSN: 1573-871X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method for measuring the temperature of monodispersed particles is studied. The method is based on the fact that the fluorescence of water solutions of fluorochromes is temperature dependent. The employed method makes it possible to reduce significantly the instability of the excitation light flux and of the optoelectronic recording apparatus.
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  • 6
    ISSN: 0392-6737
    Keywords: Quantum optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary It was found that, when metastable hydrogen 2s1/2-atoms pass through a two-electrode atomic interferometer, the yield of 2p-atoms essentially depends on the field direction. This large-scale effect can hardly be understood on the basis of quantum-mechanical concepts on the behaviour of an H-atom in electric field. In further experiments the said effect was shown to be a secondary one, namely, it arises due to transformation of the pure 2s 1/2-state into the (2s−2p)-superposition as H-atoms fly through the interferometer entrance slit.
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  • 7
    ISSN: 1432-2072
    Keywords: Key words Amphetamine ; Fluoxetine ; Intracranial self-stimulation thresholds ; Withdrawal ; Depression ; Selective serotonin reuptake inhibitors ; Psychostimulant ; Reward ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Withdrawal from chronic amphetamine administration is characterized by deficits in reward that resemble some symptoms of depression. Nevertheless, the effects of long-term administration and withdrawal from other drugs, such as fluoxetine, that have the potential to elevate mood in depressed individuals have not been characterized. Objectives: The purpose of this study was to characterize the effects of withdrawal from chronic amphetamine or fluoxetine administration on central reward function. Furthermore, the effects of acute or chronic pretreatment with fluoxetine on responsiveness to an acute amphetamine challenge were examined to identify potential interactions between the two drugs. Methods: A rate-independent discrete-trial threshold procedure was used to characterize self-stimulation behavior in rats prepared with bipolar electrodes in the medial forebrain bundle. Results: Elevations in intracranial self-stimulation (ICSS) thresholds, reflecting a decrease in the reward value of the stimulation, were associated with withdrawal from various chronic amphetamine treatment regimens (1–5 mg/kg, three injections per day for 1, 2, 4 or 6 days). The magnitude and duration of threshold elevations were proportional to the duration and dose of amphetamine treatment prior to withdrawal. In contrast, no alterations in ICSS thresholds were associated with withdrawal from chronic fluoxetine treatment (5 mg/kg/day for 15 days). While neither acute nor chronic administration of fluoxetine alone altered ICSS thresholds, chronic pretreatment with fluoxetine blocked the threshold-lowering effect of acute amphetamine administration (4 mg/kg), but acute pretreatment did not. Amphetamine-induced decreases in response latency, a measure of motor performance, were not affected by either chronic or acute fluoxetine pretreatment. Conclusions: The results of these experiments suggest that chronic fluoxetine treatment may induce adaptive changes in serotonergic transmission that, in themselves, do not alter the function of central reward processes, but may alter the ability of amphetamine to potentiate ICSS reward. In addition, the lack of change in ICSS thresholds during withdrawal from the chronic fluoxetine treatment regimen used suggests that withdrawal from all mood-altering drugs may not necessarily produce changes in central reward functions.
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  • 8
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé Etude par ATD et par spectroscopie infrarouge (IR) de l'effet de la teneur en antioxydant (Néozone D) et en catalyseur d'oxydation (cuivre dispersé) sur l'oxydation du polyéthylène fondu, en conditions non isothermiques (échauffement des échantillons à vitesse constante). L'augmentation de la teneur en antioxydant ou en catalyseur d'oxydation donne des résultats similaires, c'est-à-dire une diminution de l'épaisseur de la couche superficielle oxydée, et, par suite, de la quantité oxydée totale des échantillons de polyéthylène. Ceci est dû à l'augmentation de la vitesse de l'oxydation du polymère.
    Abstract: Zusammenfassung Differentialthermoanalyse (DTA) und Infrarotspektroskopie (IR) wurden zur Untersuchung der Wirkung des Gehaltes an Antioxidantien (Neozone D) und Oxidierungskatalysator (dispergiertes Kupfer) auf die Oxidation von Polyäthylenschmelze unter nicht-isothermischen Bedingungen (unter Aufheizung der Proben mit konstanter Geschwindigkeit) eingesetzt. Die Zunahme des Gehaltes an Antioxidanz oder Oxidierungskatalysator ergibt ähnliche Ergebnisse, d. h. Herabsetzung der Stärke der oxidierten Oberflächenschicht und, dementsprechend, der Gesamtoxidationsmenge in den Polyäthylenproben. Dies ist der Zunahme der Oxidationsgeschwindigkeit des Polymers zuzuschreiben.
    Notes: Abstract Differential thermal analysis (DTA) and infrared (IR) spectroscopy have been used to investigate the effects of an antioxidant (neozone D) and an oxidation catalyst (dispersed copper) on polyethylene melt oxidation under nonisothermal conditions (samples were heated at a constant rate). An increase in the content of the antioxidant or the oxidation catalyst gives similar results: a decrease in the thickness of the oxidized surface layer and accordingly in the total amount of oxidation in polyethylene samples. This is due to an increase in the rate of oxidation of the polymer.
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  • 9
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Fünfzehn Patienten mit HBsAg-positiver, schwerer chronisch aktiver Hepatitis, von denen neun DNS-Polymerase (DNAP)-positiv und sechs -negativ waren, erhielten eine intravenöse Therapie mit Adenin-Arabinosid (Ara-A) in einer Dosis von 10 mg/kg/Tag an fünf aufeinanderfolgenden Tagen während zwei aufeinanderfolgenden Wochen. Von den DNAP-positiven Patienten sprachen zwei mit einer histologischen und klinischen Remission an, sie wurden außerdem anhaltend DNAP-negativ. Es wurden jedoch auch histologische und klinische Remissionen bei Patienten mit einer unbefriedigenden DNAP-Antwort und sogar bei DNAP-negativen Patienten beobachtet. Es wird angenommen, daß Ara-A möglicherweise außer seinem antiviralen Effekt noch einen anderen Wirkmechanismus hat, wie etwa immunsuppressive Aktivität, durch den die histologische und klinische Remission induziert wurde. Auf der anderen Seite kann das unterschiedliche Verhalten mit dem natürlichen Verlauf der chronischen Hepatitis B in Zusammenhang stehen. Kontrollierte Studien zur Feststellung der Wirksameit von Ara-A oder anderen Substanzen in der Therapie der chronischen Heptatitis B sind daher dringend erforderlich.
    Notes: Summary Fifteen patients with HBsAg-positive, severe chronic active heptatitis, nine DNA polymerase (DNAP)-positive and six negative were treated with intravenous adenine arabinoside (Ara-A) in a dose of 10 mg/kg/day for five consecutive days during each of two consecutive weeks. Of the DNAP-positive patients, two responded with histological and clinical remission as well as permanent loss of DNAP. However, histological and clinical remission were also observed in patients with unsatisfactory DNAP response and even in DNAP-negative patients. It is suggested that, in addition to its antiviral effect, Ara-A might have another mechanism, such as immunosuppression, that induced histological and clinical remission. Alternatively, the discrepancy of response might relate to the natural course of chronic type B hepatitis. Accordingly, controlled trial is mandatory for assessing the effect of Ara-A or any other agent in the treatment of chronic type B hepatitis.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 106 (1999), S. 149-158 
    ISSN: 1573-6857
    Keywords: X-ray ; protein structure ; databases ; database management systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The protein data bank (PDB), at Brookhaven National Laboratory, is a database containing information on experimentally determined three-dimensional structures of proteins, nucleic acids, and other biological macromolecules, with approximately 9000 entries. The PDB has a 27-year history of service to a global community of researchers, educators, and students in a wide variety of scientific disciplines. Data are easily submitted via PDB's WWW-based tool AutoDep, in either PDB or mmCIF format, and are most conveniently examined via PDB's WWW-based tool 3DB Browser. Collaborative centers have been, and continue to be, established worldwide to assist in data deposition, archiving, and distribution.
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