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  • 1
    Electronic Resource
    Electronic Resource
    Theory of the collisional presheath in a magnetic field parallel to the wall (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 2486-2495 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the limit of a small Debye length (λD→0) the plasma boundary layer in front of a negative absorbing wall is split up into a collision-free planar space charge sheath and a quasineutral presheath, where the ions are accelerated to fulfill the Bohm criterion. Apart from ion inertia, the mechanism of the presheath depends on an additional effect controlling the ion field acceleration. The present paper considers a stationary presheath dominated by the deflection of the ion orbits in a magnetic field parallel to the wall. The ion transport is provided by charge exchange collisions with cold neutrals. The potential profiles and ion distributions resulting from the self-consistent kinetic analysis are compared with expectations based on a previous hydrodynamic model. The transition from "closed'' to "open'' ion orbits results in typical deviations near the sheath edge. The kinetic Bohm criterion is found to be fulfilled marginally. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871966
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  • 2
    Electronic Resource
    Electronic Resource
    Particle simulation of a magnetized plasma contacting the wall (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 117-126 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: One-dimensional particle simulations are performed to study the influence of a strong magnetic field on the plasma boundary layer in front of a completely absorbing wall. The magnetic field lines are parallel to the wall, and the ion transport is provided by charge exchange collisions with cold neutrals. The Debye length is small compared with the ion gyroradius and the electrons are Boltzmann distributed. A modified Particle-in-Cell Monte-Carlo-Collision (PIC-MCC) code is developed to avoid the problem of different time scales of electrons and ions. The self-consistent steady-state simulation is performed for a system with one spatial coordinate and two velocity components (1d, 2v). The results are compared with corresponding results of a self-consistent stationary solution of the ion Boltzmann equation. Although the potential and density profiles are essentially confirmed, the ion velocity distribution functions disagree with analytic solutions in certain singular regions unless certain pertubations in the electric field are suppressed. It is shown that this is due to a microscopic instability of the stationary solution. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872680
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  • 3
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    Moral oder Klugheit? Überlegungen zur Gestalt der Autonomie des Politischen im Denken Kants (1990)
    Berlin : Periodicals Archive Online (PAO)
    Kant-Studien. 81:4 (1990) 413 
    Details
    ISSN: 0022-8877
    Topics: Philosophy
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:0171-1990-081-04-000002
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  • 4
    Electronic Resource
    Electronic Resource
    The rate of protein synthesis in needles of Norway spruce (Picea abies): Light stimulation, regulation through photophosphorylation, stress enhancement (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 87 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The incorporation of 14C-leucine into the total-protein fraction of needles of Norway spruce (Picea abies [L.] Karst.) during short time incubation was used as a measure of protein synthesis in the light and in the dark. Light saturation curves, obtained for needles of different ages (new flush and 1 and 2 years old) or at different seasons (summer-winter) followed the Michaelis-Menten algorithm, exhibiting marked differences with regard to light saturation (Vmax) and the half-saturation constant (K5. 2). The light saturation curves of ATP level (mg g−1 fresh weight) and of leucine incorporation into protein (nmol mg−1 h−1) matched each other, suggesting that photophosphorylation may be decisive for the rate of protein synthesis in the light. This is confirmed by the action spectrum of leucine incorporation. which resembled an action spectrum of leaf photosynthesis, and also by partial inhibition of protein synthesis by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), an inhibitor of non-cyclic photophosphorylation. Light stimulated protein synthesis showed pronounced seasonal fluctuations with a summer maximum.Furmigation of 5 years old spruce trees for 3 months with SO2 in combination with O3 and/or NO2 caused a distinct enhancement of the protein synthesis rate in the light and, at a reduced absolute level, also in the dark. A similar result was obtained for 40 to 70 years old spruce stands when healthy and sick trees were compared: the latter being afflicted by the novel type of forest decline, which is characterized by yellowish bronze discolouration of sun-exposed older needles and partial loss of older needle generations (3 to 4 years old). The 1 year old needles of the unhealthy trees showed a markedly increased 14C-leucine incorporation rate which, in the dark, was even more pronounced than in the light. Stress-physiological mechanisms, which could possibly explain this stimulation, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb00149.x
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  • 5
    Electronic Resource
    Electronic Resource
    The photomechanic infrared receptor for the detection of forest fires in the beetle Melanophila acuminata (Coleoptera: Buprestidae) (1998)
    Springer
    Journal of comparative physiology 182 (1998), S. 647-657 
    Details
    ISSN: 1432-1351
    Keywords: Key words Infrared receptor ; Mechanoreceptor ; Fire ecology ; Insect cuticle ; Photoacoustics ; Remote sensing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We recorded from single units of individual sensilla of the thoracic infrared (IR) pit organs of Melanophila acuminata. When the organ was stimulated with a thermal radiator whose emission spectrum was similar to that of a typical forest fire, units responded phasically with up to seven spikes within 30–40 ms at a radiation power of 24 mW cm−2. In the experiments all wavelengths shorter than 1.6 μm were excluded by a longpass IR filter. Response latencies were about 4 ms and initial impulse frequencies were up to 250 impulses per second (ips). A single spike could be generated even when stimulus duration was only 2 ms. Reduction of total radiation power from 24 mW cm−2 to 5 mW cm−2 resulted in increased response latencies of 5–6 ms and the occurrence of only two to three spikes. Initial impulse frequencies decreased to 125 ips. According to our physiological results and calculations, Melanophila should be able to detect a 10-hectare fire from a distance of 12 km. Mechanical stimuli also evoked responses of the IR sensilla. All present morphological and physiological findings lead to the conclusion that the IR receptors of Melanophila must function by means of a hitherto undescribed photomechanic mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050210
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  • 6
    Electronic Resource
    Electronic Resource
    Biomechanical aspects of claviculectomy – case report of a rower with Ewing's sarcoma (1998)
    Springer
    Der Unfallchirurg 101 (1998), S. 153-157 
    Details
    ISSN: 1433-044X
    Keywords: Key words Claviculectomy • Ewing's sarcoma • Tumours • Biomechanics of the shoulder girdle ; Schlüsselwörter Klavikularesektion • Ewing-Sarkom • Tumoren • Biomechanik des Schultergürtels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die extraperiostale Klavikulektomie, welche bei den seltenen bösartigen Tumoren indiziert ist, bleibt nach Kortikalisdurchbruch aufgrund fehlender Weichteilkompartimentierung in der Regel marginal. Hinsichtlich der biomechanischen Bedeutung der kompletten Resektion für den Schultergürtel herrscht in der Literatur Uneinigkeit, welche wohl auf die unterschiedlichen muskulären Kompensationsmechanismen der untersuchten Patienten zurückzuführen ist. Wir berichten über die komplette Schlüsselbeinentfernung mit begleitender Chemo- und Strahlentherapie bei einem 18jährigen Ruderer mit Ewing-Sarkom. Bereits 16 Monate nach der Operation zeigt sich klinisch und radiologisch ein ausgezeichnetes Ergebnis. 36 Monate nach dem Eingriff ist der Patient ohne Anhalt für ein Lokalrezidiv oder Fernmetastasen in der Lage, den Rudersport wieder beschwerdefrei auszuüben. Anhand biomechanischer Überlegungen, welche die zentrale Rolle des M. trapezius bei der Kompensation der defektbedingten skapulothorakalen Instabilität zeigen, werden Hinweise für die Rehabilitation gegeben.
    Notes: Summary Because of poorly compartmentalized paraclavicular soft tissues, total extraperiostal claviculectomy in cases of malignoma with cortical destruction is always marginal. Due to different muscular compensation in the patients examined, literature disagrees on the biomechanical consequences of claviculectomy for the shoulder girdle. We present a case of total clavicula resection including chemotherapy and radiation in an 18-year-old rower with Ewing's sarcoma. Sixteen-month postoperative radiological and clinical examination revealed an excellent result. Thirty-six months postoperatively the patient is able to row symptom-free without any evidence of the disease. Biomechanical reflections on the significance of the trapezius muscle in compensating thoracoscapular instability provide information for rehabilitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001130050248
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  • 7
    Electronic Resource
    Electronic Resource
    Osteoplastic frontal sinusotomy and extradural microsurgical repair of frontobasal cerebrospinal fluid fistulas (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 245-254 
    Details
    ISSN: 0942-0940
    Keywords: Cerebrospinal rhinorrhoea ; ethmoid sinus ; frontal sinus ; head injury ; skull base tumours
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The choice of the surgical approach and operative technique for the management of cerebrospinal fluid (CSF) fistulas of the anterior cranial fossa are still a controversially discussed topic. Although “extracranial” approaches through the paranasal sinuses are becoming increasingly more popular among otolaryngologists and maxillo-facial surgeons, most neurosurgeons traditionally prefer the “intracranial” repair of CSF fistulas by a craniotomy. We present an approach through the frontal sinus for the repair of dural defects behind the posterior wall of the frontal sinus and at the floor of the anterior cranial fossa. The operative procedure comprises the following main steps: 1) exposure of the anterior wall of the frontal sinus by a bicoronal incision; 2) excision of the anterior wall without frontal burr holes; 3) bilateral removal of the posterior wall of the fronal sinus; 4) extradural inspection of the dura behind the frontal sinus and above the cribriform plate, ethmoidal roof, and orbital roof bilaterally; 5) closure of dural tears by direct suture and a periosteal graft; 6) reinsertion of the anterior wall of the frontal sinus and fixation with titanium micro plates. Twenty-five patients operated upon using this technique are described. The aetiology of the frontobasal lesion was traumatic in 23, and an ethmoid carcinoma in two. In all patients, the dural fistulas were successfully repaired during the initial procedure. One patient died from sudden circulatory arrest after an uneventful postoperative course of nine days. Otherwise, there were no postoperative complications. This technique affords atraumatic extradural inspection and repair of dural fistulas bilaterally behind the frontal sinus, and above the cribriform plate and the ethmoidal and orbital roofs with none or minimal brain retraction. It therefore allows early repair of CSF fistulas also in patients with severe brain injury. Although we consider the extradural closure of fistulas the method of choice, this approach also allows for a combined extradural-intradural procedure, thus enabling the surgeon to treat associated intradural pathologies, such as traumatic lesions or tumours of the frontal cranial base.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411734
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of the calcium antagonists nifedipine, nitrendipine, nimodipine and nisoldipine on oesophageal motility in man (1991)
    Springer
    European journal of clinical pharmacology 41 (1991), S. 313-316 
    Details
    ISSN: 1432-1041
    Keywords: Calciumantagonists ; Oesophageal motility ; oesophageal pharmaco-manometry ; lower oesophageal sphincter pressure ; healthy volunteers ; dihydropyridines ; nifedipine ; nifedipine ; nisoldipine ; nitrendipine ; nimodipine ; side ; effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Nifedipine has been proven to be effective and safe in the treatment of primary oesophageal motility disorders which can cause angina-like chest pain and/or dysphagia. The effects of the calcium channel blockers nifedipine, nitrendipine, nimodipine and nisoldipine on oesophageal smooth muscle function in healthy male volunteers were studied by oesophageal manometry using the rapid pull-through-technique, in two randomized, double-blind crossover studies. Lower oesophageal sphincter pressure, oesophageal contraction amplitude and duration after a wet swallow (measured 5 cm and 10 cm above the lower oesophageal sphincter) were determined 30 min before and at 10 minute intervals up to 90 min after the administration of nimodipine and up to 120 min after nifedipine, nitrendipine and nisoldipine. The plasma drug concentration was measured at baseline (−15 min) and in parallel with the manometric measurements. Compared to placebo, lower oesophageal sphincter pressure was significantly decreased by 24% by nifedipine and 17% by nimodipine, whereas the effects of nitrendipine (decrease of 15%) and nisoldipine (9%) were not significant. Nifedipine significantly decreased by 17% the oral contraction amplitude compared to placebo and nimodipine by 11%. The duration of the contraction amplitudes was not altered. The decrease in sphincter pressure was correlated with the corresponding plasma drug levels of nifedipine r=0.92, nitrendipine r=0.80 and nisoldipine r=0.79. Nimodipine showed no such correlation. It is concluded that among the calcium antagonists studied, nifedipine exerted the strongest effect on oesophageal smooth muscle function, so it appears to be the most suitable compound for the treatment of primary motor abnormalities of the oesophagus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314958
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation and properties of raney nickel electrodes on Ni-Zn base for H2 and O2 evolution from alkaline solutions Part I: electrodeposition of Ni-Zn alloys from chloride solutions (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 705-710 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Experimental results for the electrodeposition of Ni-Zn alloys from chloride solutions, with addition of H3BO3 and without other additives, in a laboratory cell with a perforated nickel sheet cathode and with recirculating electrolyte are presented. The dependence of the zinc content in the alloy on the following operating conditions was investigated: cathodic current density, 1.0–20.0 A dm−2; temperature, 35–65°C; pH 1.5–5.5; total molarity,M tot=M Ni 2+ +M Zn 2+ =1.1–2.8 M; and, molar ratio,P=M Ni 2+ /M Zn 2+ =1.0–15. Depending on the operating conditions the Zn content in the alloy varied over the range 22–88 mol%. In separate experiments galvanostatic polarization curves were measured in the direction of increasing and then decreasing cathodic current density in the range 0.1–20.0 A dm−2 with all other operating conditions as used for electroplating experiments. In all cases significant hysteresis effects were observed. It was found that the current efficiency for the electrodeposition of Ni-Zn alloys from chloride solutions as a function of the zinc content in the alloy showed a sharp minimum of about 55% atX Zn=55 mol % irrespective of other operating conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01027497
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  • 10
    Electronic Resource
    Electronic Resource
    Preparation and properties of Raney nickel electrodes on Ni-Zn base for H2 and O2 evolution from alkaline solutions Part II: Leaching (activation) of the Ni-Zn electrodeposits in concentrated KOH solutions and H2 and O2 overvoltage on activated Ni-Zn Raney electrodes (1992)
    Springer
    Journal of applied electrochemistry 22 (1992), S. 711-716 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The partial dissolution of zinc from electrodeposited Ni-Zn alloys (withX Zn 0 =22–87.3 mol %) was studied, in cold and nearly boiling 10m KOH. It was found that alloys withX Zn 0 ≤22 mol % are not dissolved at all. The dissolved zinc fraction,A, increased rapidly with further increase in zinc content and after having passed a maximum withA=82–90% atX Zn 0 =55–58 mol % and a sharp minimum withA=52–65% atX Zn 0 =65–69 mol %, it asymptotically approached toA → 100% atX Zn 0 → 100 mol %. The discontinuous dependence ofA againstX Zn 0 may be explained by differences in the crystallographic composition of the alloy deposits. Alloys withX Zn 0 〈50–60 mol % can be allocated to solid solutions of zinc in the Ni matrix (α-phase); the range of 50–60〈X Zn 0 〈70–80 mol % corresponds to the coexistence of α+γ phases. The pure γ-phase exists within a narrow range atX Zn 0 =75–80 mol %. No zinc dissolution from Ni-Zn alloys withX Zn 0 ≤22 mol % was explained by extremely low zinc activities in dilute solid solutions of the α-phases shifting the Gibbs energy of the dissolution reaction to very low negative, or even to positive values. The dependence of the hydrogen and oxygen overvoltage atj=0.4 A cm−2 in 10m, KOH at 100°C on the original zinc contentX Zn 0 showed, in both cases, a clear minimum atX Zn 0 =75–78 mol %. This points to a practically pure γ-phase in the original Ni-Zn alloy with an approximate composition NiZn3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01027498
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