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  • 1
    Electronic Resource
    Electronic Resource
    Optical heterodyne detection at a silver scanning tunneling microscope junction (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 1311-1316 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The 435 MHz beat signal between two modes of a He–Ne laser (633 nm) has been detected in the current of a scanning tunneling microscope (STM), using a silver probe to enhance the sensitivity using its plasmon resonance. The difference frequency between this optical beat and a radio frequency voltage applied to the junction has also been detected in the STM current. The difference frequency and heterodyne signals, as well as the direct current (dc) probe expansion, fit a calculation of modulated and dc thermal expansion of the probe tip, once one assumes that a surprisingly large fraction of the laser beam is absorbed at a small structure at the probe end. The beat signal due to current rectification is not observed for the experimental conditions, but the potential for utilizing the plasmon resonance to obtain such a signal using a silver probe is evaluated for other, feasible conditions where it might provide exceptional sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369332
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of air pollutants on proton and sucrose transport at the plasma membrane of Ricinus communis (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of the air pollutants O3, SO2 and NO2 on aspects of sucrose/proton cotransport across the plasma membrane of Ricinus communis plants have been investigated. The H+-ATPase hydrolytic activity in cotyledon plasma membrane vesicles purified by phase partitioning showed small stimulations by Na2SO3 or NaNO3 added separately or together to the assay medium. ATPase activity from plants pretreated by fumigation with SO2 or O3 also showed an increase, the effect of O3 being quite marked. Plasma membrane H+-pumping in KI-treated microsomal fractions and medium acidification by intact cotyledons both showed small decreases in the presence of Na2SO3 or NaNO2. Both Na2SO3 and NaNO2 at high concentrations (2 mol m–3) had significant effects on sucrose uptake by intact cotyledons, although sucrose efflux was unaffected. No significant effects on sucrose uptake or efflux by intact cotyledons were observed in plants pretreated by fumigation with SO2 or O3. Proton-coupled sucrose transport in isolated plasma membrane vesicles was inhibited in the presence of Na2SO3 or NaNO2. However, both pollutants also significantly inhibited the uptake of acetate by the vesicles, indicating a dissipation of the pH gradient across the membrane. It was concluded that no specific aspect of the sucrose/proton cotransport mechanism was damaged by these air pollutants, and that the effects of these pollutants on carbohydrate partitioning are more likely to be due to general effects on membrane integrity or on other aspects such as leaf carbohydrate metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00402.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Prolonged intrathecal catheterisation after inadvertent dural taps in labour (1999)
    Oxford : Blackwell Science Ltd
    Anaesthesia 54 (1999), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2044.1999.96794t.x
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  • 4
    Electronic Resource
    Electronic Resource
    Glucose, and not sucrose, is transported from wheat to wheat powdery mildew (1999)
    Springer
    Planta 208 (1999), S. 426-430 
    Details
    ISSN: 1432-2048
    Keywords: Key words:Erysiphe (carbon source) ; Glucose transport ; Powdery mildew ; Sugar transport ; Triticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The main host carbon energy source transferred from wheat leaves (Triticum aestivum L.) to wheat powdery mildew (Erysiphe graminis f.sp. tritici) has been investigated in three ways. When the uptake of sugars by isolated mycelial suspensions was examined, the uptake rate for glucose was considerably higher than that for a range of other solutes. Analysis by high-performance liquid chromatography of leaf and mycelial extracts following uptake of sugars into infected leaf pieces confirmed that sucrose was rapidly hydrolyzed in the leaf; no sucrose or fructose could be detected in mycelial extracts. Furthermore, studies of the uptake of asymmetrically labelled sucrose indicated that this sugar is cleaved prior to uptake by the pathogen. Thus several lines of evidence show that glucose, and not sucrose, is the major carbon energy source transferred from host to fungal mycelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050578
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Insertion, efficacy, and removal of a nonendoscopically removable percutaneous endoscopic gastrostomy (PEG) tube (1999)
    Springer
    Surgical endoscopy and other interventional techniques 13 (1999), S. 516-519 
    Details
    ISSN: 1432-2218
    Keywords: Key words: Percutaneous endoscopic gastrostomy — Enteral access
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Externally removable PEG tubes require an internal bumper that can collapse to a size that is small enough to allow for its removal through the abdominal wall by external traction. Adequate force must be maintained to avoid accidental dislodgement of the tube prior to its desired removal. Methods: A nonendoscopically removable PEG (Inverta-PEG, Ross Products Division, Abbott Laboratories, Columbus, OH, USA) was evaluated in a nonmasked, prospective clinical study involving 131 patients enrolled by 25 physicians. The over-the-wire (Sacks-Vine) technique was used for all placements. After insertion, patients were followed weekly for 8 weeks. During week 9, the PEGs were removed percutaneously (nonendoscopically). Insertion, efficacy, and removal performance were evaluated. Results: Complication rate during insertion was 1.5% and removal was 1.2%. Qualitatively, investigators rated ease of insertion and removal as very easy, easy, average, difficult, or very difficult. Investigators rated 98.5% of insertions as very easy, easy, or average; 95.4% of removals were rated as very easy, easy, or average. Some patients exited the study prematurely due to leakage around the stoma (2.3%) and inadvertent tube removal (5.3%). These complication rates were consistent with earlier reports of other PEG studies. Conclusions: These results demonstrate that Inverta-PEG is a safe and effective tube that can be removed nonendoscopically with ease in 95% of the cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004649901025
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    GABAergic inhibition shapes frequency tuning and modifies response properties in the auditory midbrain of the leopard frog (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 479-491 
    Details
    ISSN: 1432-1351
    Keywords: Key words Iontophoresis ; Inferior colliculus ; Amphibian ; Rana pipiens ; Bicuculline ; GABA ; AbbreviationsBIC bicuculline methiodide ; CF characteristic frequency ; DNLL dorsal nucleus of the lateral lemniscus ; eFTC excitatory frequency tuning curve ; GABAγ-amino butyric acid ; IC inferior colliculus ; iFTC inhibitory frequency tuning curve ; PB phasic burst ; PL-1 primary-like 1 ; PL-2 primary-like 2 ; PL-3 primary-like 3 ; PSTH post-stimulus time histogram ; SPL sound pressure level ; SRN superficial reticular nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The functional role of GABAergic inhibition in shaping the frequency tuning of 96 neurons in the torus semicircularis of the leopard frog, Rana pipiens, was studied using microiontophoresis of the GABAA receptor antagonist, bicuculline methiodide. Bicuculline application abolished, or reduced in size, the inhibitory tuning curves of 72 neurons. In each case, there was a concommitant broadening of the excitatory tuning curve such that frequency-intensity combinations that were inhibitory under control conditions, became excitatory during disinhibition with bicuculline methiodide. These effects were observed irrespective of the excitatory tuning curve configuration prior to bicuculline methiodide application. Results indicate an important role for GABA-mediated inhibition in shaping the frequency selectivity of neurons in the torus semicircularis of the leopard frog. Bicuculline application also affected several other response properties of neurons in the leopard frog torus. Disinhibition with bicuculline methiodide increased both the spontaneous firing rate (18 cells) and stimulus-evoked discharge rate (81 cells) of torus neurons, decreased the minimum excitatory threshold for 18 cells, and altered the temporal discharge pattern of 47 neurons. Additional roles for GABAergic inhibition in monaural signal analysis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050409
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