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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 28-31 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A target of gaseous polarized hydrogen was formed by injecting polarized hydrogen atoms (produced by Stern–Gerlach spin separation) into a storage cell consisting of a cylindrical tube open at both ends. The target was placed in a storage ring to study the target characteristics (nuclear polarization, target thickness, radiation resistance). A weak transverse guide field (5 G) was applied to define the polarization direction. When atoms in a single hyperfine state were selected, the nuclear polarization of the target was measured to be 0.80±0.02. The areal density of the target under these conditions was (5.5±0.2)×1013 H/cm2, while for two spin states (applicable to experiments in high energy rings where a strong magnetic field can be applied to the target) the target thickness was found to be (8.2±0.3)×1013 H/cm2. The target polarization was unaffected by prolonged exposure of the target to beams up to 1 mA. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0649
    Keywords: 42.60 ; 42.55 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We systematically investigate the difference between both actively and passively mode-locked lasers with Gain-at-the-End (GE) and Gain-in-the-Middle (GM) at the example of Nd:YLF lasers. The GE laser generates pulse widths approximately three times shorter than a comparable GM cavity. This is due to enhanced Spatial Hole Burning (SHB) which effectively flattens the saturated gain and allows for a larger lasing bandwidth compared to a GM cavity. We first investigate enhanced SHB by measuring the cw mode spectrum, where we have observed that the mode spacing in GE cavities depends primarily on the crystal length. This was also confirmed for a Nd:LSB crystal, where the pump absorption length was significantly shorter than the crystal length. In mode-locked operation, pulse widths of 4 ps for passive mode locking and 5 ps for active mode locking are demonstrated with GE cavities, compared to 11 ps for passive and 17 ps for active mode locking with GM cavities. Additionally, the time-bandwidth product for the GE cavity is approximately twice the ideal product for a sech2 pulse shape and cannot be improved by dispersion compensation alone, while the GM cavity has nearly ideal time-bandwidth-limited performance. The results for the GM cavity compare well to existing theories taking into account the added effect of pump-power-dependent gain bandwidth which increases the bandwidth of Nd: YLF from 360 to 〉 500 GHz. In a following paper [1] (called Part II) a rigorous theoretical treatment of the effects due to SHB will be presented.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 61 (1995), S. 569-579 
    ISSN: 1432-0649
    Keywords: 42.60 ; 42.55 ; 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In Part I of this paper [1] experimental results were presented and discussed. In this part, we investigate theoretically the dynamics of end-pumped solid-state lasers due to enhanced spatial hole burning. This becomes possible by a fast numerical implementation of the saturated gain in the presence of strong spatial hole burning that allows to treat the multimode case for an arbitrary pumping level. We find for a wide range of laser parameters that the mode spacing of the cw running modes is essentially determined by the length of the gain medium and only weakly depends on the absorption depth of the pump transition. It is shown that spatial hole burning can lead to a completely flat saturated gain profile over half of the gain bandwidth. In mode-locked lasers, the flat gain due to spatial hole burning results in shorter pulses. But the pulses are neither Gaussian-nor sech-shaped as they are in actively or passively mode-locked lasers without spatial hole burning. Further, we show that soliton-like pulse shaping can be used to restore a transform-limited sech-shaped pulse in an end-pumped solid-state laser while exploiting the full gain bandwidth of the laser material.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 73 (1987), S. 401-413 
    ISSN: 1432-1939
    Keywords: Gambusia affinis ; Fat storage ; Life history strategy ; Reproductive cycles ; Comparative life histories
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We argue, based on reviewed literature covering reptiles, amphibians, birds, and fish, that fat storage may represent a life history adaptation because it enables an organism to shift in time when resources are allocated to reproduction. We applied these arguments to fat and population cycles in three populations of the mosquito fish, Gambusia affinis. For males, there appeared to be a constant size at maturation during the reproductive season. Mature males became scarce late in the summer. At the same time, immature males delayed maturity and attained much larger sizes; they matured in large numbers in the fall. The amount of stored fat tended to be equal for immature and mature males at all times except in the late summer. In the August samples, when mature males were relatively rare, they also had the lowest level of fat reserves. It appears that the older generation of mature males did not store fat and did not overwinter. At the same time, immature males registered a two to three fold increase in fat reserves. These differences in fat content between mature and immature males disappeared by September, probably because of the recruitment of a new generation of mature males. The reserves were gradually utilized during the winter. Females reproduced from the late spring through mid- to late-summer. They stopped reproducing in the late summer, when there was ample time to produce an additional litter of young. There was an inverse relationship between resources devoted to reproduction and fat reserves. As reproductive allotment decreased in the late summer, fat reserves increased. The magnitude of the change in fat reserves was similar to that displayed by males. The reserves were depleted over the winter. Significant reserves remained at the beginning of the reproductive season the following spring. Reproducing females utilized the remaining reserves significantly more rapidly than non-reproducing females. An analysis of resource availability revealed an overall decrease in food availability in the late summer, coincident with the increase in fat reserves. These cycles are therefore not attributable to changes in resource availability. They instead indicate a change in how resources are allocated by the fish. The trends in the data indicate that fat reserves are used to shift investment in reproduction from the late summer to the following spring. In males, deferring maturity, rather than maturing in August, allows them to store the necessary reserves to survive the winter so that they can mate the following spring. In females, a subset of the fat reserves is intended for producing the first clutch of eggs the following spring. The female pattern corresponds to those reported for a diversity of organisms. The possible advantages of shifting reproductive effort from the fall to the following spring include higher fecundity and higher offspring fitness. The limitations of the methodology and potential directions for future research are discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 86 (1931), S. 258-261 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1420
    Keywords: Key words Toxic shock-like syndrome (TSLS) ; necrotizing fascitis ; streptococcus pyogenes ; puerperal sepsis ; Schlüsselwörter Toxic shock-like syndrome (TSLS) ; nekrotisierende Fasziitis ; Streptococcus pyogenes ; puerperale Sepsis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Seit Mitte der achtziger Jahre häufen sich weltweit Berichte über invasive Infektionen verursacht durch Streptococcus pyogenes. In einer retrospektiven Studie wurden Häufigkeit, Symptomatik, Verlauf, Therapiemöglichkeiten und mikrobiologische Charakterisierung der Erkrankung untersucht. In die Studie wurden alle zehn Patienten (sieben weibliche/drei männliche, Durchschnittsalter 45,0 [4–71] Jahre) des Kreiskrankenhauses Reutlingen eingeschlossen, bei denen zwischen September 1994 und Mai 1996 Streptococcus pyogenes an sterilen Entnahmeorten nachgewiesen wurde. Die Isolate wurden am damaligen Nationalen Referenzzentrum (Jena) bezüglich Typisierung und Toxinbestimmung analysiert. Bezogen auf die ca. 272000 Einwohner des Landkreises Reutlingen liegen unsere Zahlen für invasive Infektionen im Bereich der in Nordamerika anhand von Populationsstudien ermittelten Daten (Inzidenzen zwischen 1,5–4,3/100000). Bei sieben Patienten war vor der akuten Krankheitsverschlechterung eine grippeähnliche Prodromalsymptomatik zu beobachten. Auffällig war eine Häufung des schwer verlaufenden „toxic shock-like syndrome“ (TSLS) mit den Kriterien: Schocksymptomatik, Multiorganversagen, Weichteilnekrose und generalisiertes Erythem (n=6). Alle überlebenden Patienten mit TSLS mußten mit mehrtägiger Respiratortherapie behandelt werden (7–16 Tage). Eine Patientin mit TSLS starb am Aufnahmetag aufgrund eines fulminanten septischen Schocks. Die Analyse der isolierten Stämme zeigte kein einheitliches Bild bezüglich der Serotypen und der Toxinbildung. Folgende sofortige therapeutische Maßnahmen sind erforderlich: antibiotische Behandlung, chirurgische Sanierung des Infektherdes und typische Intensivtherapie bei Multiorganversagen. Die beobachtete Prodromalsymptomatik unterstreicht nachdrücklich die Möglichkeit eines frühzeitigen Eingreifens in das Krankheitsgeschehen.
    Notes: Summary Since the middle of the 1980s,? reports of invasive infections caused by streptococcus pyogenes are increasing world wide. In a retrospective study the frequency, symptoms, course, therapeutic possibilities, and microbiological characterization of this disease were examined. In the study, all 10 patients (seven females/ three males, average age 45.0 [4–71]) of the district hospital of Reutlingen were included who had a proven streptococcus pyogenes infection between Sept. 1994 and May 1996, defined by isolation of group A streptococci from a sterile site. Isolates were analyzed for serotype and production of exotoxins in the National Reference Center (Jena) of that time. In relation to the approx. 272,000 inhabitants of the district of Reutlingen, our numbers for invasive infections are within the range of the data established in the USA on population-based studies (incidence between 1.5 to 4.3 per 100,000). In seven patients,? influenza-like symptoms were observed previous to the acute deterioration of the disease. There was a conspicuous accumulation of the severe courses of toxic shock-like syndrome (TSLS) with the following criteria: shock, multiorgan failure, soft tissue necrosis, and generalized erythema (n=6). All surviving patients with TSLS had to be treated during several days with assisted respiration (7–16 days). One female patient with TSLS died on the day of admittance due to an intensive septic shock. In the analysis of the isolated strains,? no uniform results regarding the serotypes and the production of exotoxins were found. The following therapeutic measures are required immediately: antibiotic treatment, surgical treatment of the infective focus, and the established intensive care therapy in cases with multiorgan failure. The observed prodromal symptoms underline emphatically the possibility of an early intervention in the course of the disease.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 212 (1985), S. 345-352 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Previous studies have shown that sexual activity increases the weight of the accessory sex glands significantly, while the organ weights correlate inversely with the assayable androgen receptor concentrations in the prostate of sexually active versus sexually resting rats. In an effort to determine the structural basis of this phenomenon, the ventral prostates of adult rats kept with female rats for 4-6 months (HE-rats) were compared to those kept in groups of 5 males in one cage (HO-rats) for the same period. As an estimate of the secretory function of the gland the concentration of prostatic binding protein (PBP) was determined in prostatic cytosols using a highly specific ELISA. Catecholamines were measured by means of HPLC and subsequent electrochemical detection. Morphological studies included immunocytochemistry of PBP, visualization of adrenergic nerves, stereological analysis of stromal and glandular compartments of the prostate, and electron microscopy of the epithelium.The main findings were as follows: (1) The prostates of HE-rats were 35% heavier than those of the HO-rats. (2) The content in secretion was in the same range in both HE-rats and HO-rats (1.5 and 1.44 mg PBP per 1 mg DNA). (3) Immunocytochemistry and electron microscopy demonstrated a very homogeneous secretion within the glandular lumen of HO-rats with a diminished amount of secretory material within the glandular cells.In HE-rats the glandular lumina were clearly larger in diameter and intraluminal secretion was less homogeneously stained. The height of the epithelium was increased and the individual secretory cells contained several secretory granules. Within the prostatic stroma the profiles of adrenergic nerves were more numerous in HE-rats, and a greater total amount of noradrenaline was present. At the fine structural level signs of enhanced membrane turnover, such as lysosomal structures, were prominent in prostatic epithelium of HE-rats, while in HO-rats mostly dense bodies were observed. The results indicate that sexual activity results in the functional adaption (activity hypertrophy) of the prostate as a result of nerve-associated control of glandular activity.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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