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  • 2005-2009  (1)
  • 1995-1999  (3)
  • 1985-1989  (3)
  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8798-8807 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Epitaxial CoSi2/Si/CoSi2 and CoSi2/Si/poly-PtSi heterostructures were grown with molecular-beam epitaxy onto Si(111). Characterization of the heterostructures with scanning tunneling microscopy, Rutherford backscattering spectrometry, and transmission electron microscopy revealed very high structural quality. We report on the application of these heterostructures to a wavelength-tunable infrared detector. It consists of two back-to-back Schottky contacts separated by the thin (1000–2000 A(ring)) undoped Si spacer layer. The different Schottky barrier heights which photocreated charge carriers in the silicides have to surmount can be used to control the cutoff wavelength by simply varying the applied bias across the structure. Photoelectric measurements of so-called symmetrical sensors made of CoSi2/Si/CoSi2 where both silicides contribute equally to the photocurrent, yielded a bias dependence of the cutoff energy three times as large as predicted by the conventional Schottky effect. In this case, the observed tunability of the cutoff energy can be explained only by considering ballistic transport of photocreated carriers (holes and electrons) in the silicon. Different mean free path lengths of hot electrons and holes in Si lead to a strongly bias-dependent ratio of the collected photoelectrons and photoholes. Photocurrents measured in asymmetrical sensors made of CoSi2/Si/PtSi were found to change phase as a function of light energy at a constant bias. This change of photocurrent direction can also be understood with the proposed energy band diagram and ballistic transport of hot carriers in Si. This kind of device showed a tunability of the cutoff energy between 0.3 and 0.5 eV. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 67 (2005), S. 0 
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Variation in fecundity was examined from 32 populations of Arctic charr Salvelinus alpinus in eastern North America covering a range of 37° latitude and extending from Maine, U.S.A., to northern Ellesmere Island in the Canadian Arctic. Populations were classed as dwarf, normal or anadromous and covered a suite of different habitat and climatic regimes. Fecundity varied with fork length (LF), with LF adjusted fecundity differing significantly among populations within each of the morphotypes implying that fecundity was a continuously responsive trait influenced by local environmental factors. Latitudinal variation in fecundity was also evident among morphotypes when the simultaneous effects of both latitude and LF were controlled. There was a significant trade-off between fecundity and egg size in two of five populations of anadromous Arctic charr, but no evidence in limited data from either normal or dwarf populations. In contrast with some other studies of fecundity in salmonids, there was no evidence for a latitudinal cline in egg size.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 1018-1020 
    ISSN: 1600-5759
    Quelle: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Thema: Chemie und Pharmazie , Geologie und Paläontologie , Physik
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 350 (1995), S. 327-341 
    ISSN: 1434-601X
    Schlagwort(e): 25.70.Gh ; 25.70.Jj ; 25.70.Pq
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In a multidetector experiment on 26 or 30 AMeV32S+58Ni, up to four coincident heavier or intermediate-mass fragments were observed. One of these occasionally has the characteristics of a projectile-like fragment, up to three may be attributed to the decay of the heavy reaction product. Taking the velocity of the fragments as a measure of the heavy-product excitation energy, one finds evaporation, fission and multifragmentation to follow one another with rising excitation. Model simulations of sequential decay with up to two binary fissions and, alternatively, of simultaneous statistical multifragmentation were performed for comparison with experimental distributions of mass, velocity and (for events with three slow intermediate-mass fragments) relative azimuthal angle. Though in the three-fragment events indications of simultaneous multifragmentation are present, the sequential binary decay predominates. Evaporated protons and α particles detected in coincidence have a mean multiplicity growing with excitation energy, while the temperature governing the spectra has a plateau with a value of about 5.5 MeV.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-2013
    Schlagwort(e): Event-related cross-correlation ; Spike train analysis ; Signal transmission ; Motor units ; Muscle spindle afferents
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A method is presented for computing correlation coefficients of two (or more) output spike trains in temporal relation to one (or more) input event trains. These event-related correlation functions are computed by convolving the output spike trains, represented as point processes, with rectangular pulses of selectable width, and by then calculating linear correlation coefficients for the pairs of amplitude values obtained from the two convolved processes in temporal relation to the input events. The merits of this technique are illustrated on stimulus trains delivered to motor units (MUs) and output spike trains recorded from muscle spindle afferents of the same cat hindlimb muscle. The correlation functions obtained show the temporal course of the correlated firings of the two afferents (mostly Ia afferents from primary muscle spindle endings) as a function of time from MU activation; they are compared with the conventional cross-correlation histograms (CCHs) between afferents and with peri-stimulus time histograms (PSTHs) between stimulus and afferent firing patterns. Stimulus-related cross-correlation functions as displayed here can be calculated for any three spike trains. Possible extensions of the method to larger numbers of input and output channels are also discussed.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1435-2451
    Schlagwort(e): Gastric wall ; Laser-hydrothermosounds ; Tissue lesion ; Guideline for secure therapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In der vorliegenden Studie sollen die Auswirkungen der endoskopisch angewandten Hydrothermo- und Lasercoagulation auf die humane Magenwand in vivo näher definiert werden. Ziel ist es, das Ausmaß der Gewebsschädigung bei verschiedenen Applikationsenergien festzustellen, um so eine für den Patienten sichere Anwendung zu gewährleisten. Bei 8 Patienten, die wegen eines Magencarcinoms zur Gastrektomie vorgesehen waren, wurden bei der routinemäßigen präoperativen Gastroskopie Coagulationsmarken mit beiden Energieträgern auf die dem Tumor benachbarte normale Schleimhaut des Antrum gesetzt. Wir verwendeten einen Neodymium YAG Laser (maximale Leistung 70 W, Applikationsdauer variiert zwischen 1 und 3 s) sowie die monopolare Elektrohydrothermosonde (Erbotom, maximale Leistung 170 W, Applikationsdauer zwischen 1 und 3 s). Die Gastrektomie erfolgte innerhalb von 3–6 Tagen nach Setzen der Coagulationsmarken. Beim Vergleich der Hydrothermosonden- und Lasercoagulationsmarken fand sich, daß die Hydrothermosonde bei gleicher Applikationsdauer größere Nekrosezonen verursachte als der Laser. In der histologischen Untersuchung konnte eine direkte Korrelation zwischen dem oberflächlichen Durchmesser und der Eindringtiefe der Nekrose gefunden werden. Die Läsionen reichten bei der maximalen Applikationsdauer bis an die Serosa. Eine Läsion der Serosa selbst konnte nie festgestellt werden. Die endoskopische Behandlung mit Hydrothermosonden- bzw. Lasercoagulation ist bei Einhaltung der angegebenen Maximalwerte sicher, da an unseren Präparaten nie eine Serosaläsion festgestellt werden konnte. Blutende Läsionen können mit mehr Leistung coaguliert werden, da ein Teil der Energie durch das ausgetretene Blut absorbiert wird.
    Notizen: Summary Effect of thermic and laser energy applied onto human in vivo gastric wall has not yet been reported in literature. In our study we evaluated the maximum amount of energy not harming the patient as well as principles for secure and sufficient therapy. In 8 patients hospitalized for gastric resection we applied vaporization by laser- and hydrothermosounds in this part of the stomach which should be resected. Endoscopic pictures were taken. We used a NdYAG laser (maximum performance 70 W, time of application 1–3 s) and hydrothermosounds (maximum performance 170 W, time of application 1–3 s). The stomach was resected 3–8 days following application. Comparing laser- and hydrothermosounds marks we observed a bigger area of necrosis at hydrothermosounds marks using the same amount of energy. In histological investigation correlation between depth and diameter of necrosis was found. After the same application time both depth and diameter of necrosis were bigger by hydrothermosounds than by laser. Lesions reached serosa at the maximum time of application of 3 s. Serosal lesion itself did not appear. Endoscopic treatment of tissue lesion by laser and thermic irradiation (vaporization of bleeding polyp pedicles, treatment of tumors) is secure using the maximum energy mentioned above. Serosal lesion did not appear. Bleeding lesions must be treated by higher energy because of absorption of energy by escaped blood.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 333 (1989), S. 319-320 
    ISSN: 1434-601X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have searched for neutrons from a Pd-electrode loaded with deuterium in electrolysis setups similar to those of Fleischmann and Pons [1] and Jones et al. [2]. Within the sensitivity of our neutron detection system corresponding to a neutron source strength of 5 x 10− 2 neutrons/s we did not find any neutrons due to ‘cold nuclear fusion’. We emphasize the necessity of using several independent neutron detectors.
    Materialart: Digitale Medien
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