Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1020-1027 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the nature of low-power nonlinear effects in high-temperature superconducting microwave devices by measuring third harmonic generation at 76 K in coplanar waveguide transmission lines of different geometries fabricated from YBa2Cu3O7−δ thin films. The measured power in the third-harmonic signal changes systematically with film thickness, center conductor linewidth, and line length. We analyze these results using a simple model for a transmission line with a nonlinear inductance arising from a current-dependent superconducting penetration depth. This analysis describes quantitatively the observed differences in harmonic generation for transmission lines of different dimensions, and yields a single geometry-independent parameter (the nonlinear scaling current density J0) to quantify the observed nonlinear behavior. For the thin film samples studied here J0=3.0×107 A/cm2 at 76 K for all geometries investigated. These results provide the means to establish a lower limit for the expected nonlinear response of superconducting components of arbitrary geometry at microwave frequencies. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To determine whether corticotrophin releasing hormone plays a role in the regulation of tone in tern nonlabouring human myometrium.Setting A teaching hospital research laboratory.Sample Thirty-seven women undergoing elective nonlabour caesarean section under regional anaesthesia.Methods Human corticotrophin releasing hormone (1, 10, 100 nmol/L) was added to strips of term, nonlabouring myometrium mounted in an organ bath, and the effect on spontaneous, oxytocin (1 nmol/L) or prostaglandin F2α (100 nmol/L) stimulated contractions determined. Cyclic adenosine monophosphate (CAMP) content of the tissue was also determined by enzyme immunoassay.Results Corticotrophin releasing hormone did not affect myometrial tension development in any of the experimental protocols. cAMP increased transiently after addition of corticotrophin releasing hormone (166.7 ± 12.7% at 1 minute) but this was not reflected by any change in tension.Conclusions This study suggests that despite high maternal plasma concentrations of corticotrophin releasing hormone in pregnancy at term, this peptide is unlikely to play a direct role in the control of myometrial contractility in nonlabouring myometrium.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 22 (1999), S. 0 
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Optimizing lead placement in transvenous defibrillation remains central to the clinical aspects of the defibrillation procedure. Studies involving superior vena cava (SVC) return electrodes have found that left ventricular (LV) leads or septal positioning of the right ventricular (RV) lead minimizes the voltage defibrillation threshold (VDFT) in endocardial lead→SVC defibrillation systems. However, similar studies have not been conducted for active-can configurations. The goal of this study was to determine the optimal lead position to minimize the VDFT for systems incorporating an active can. This study used a high resolution finite element model of a human torso that includes the fiber architecture of the ventricular myocardium to find the role of lead positioning in a transvenous LEAD→can defibrillation electrode system. It was found that, among single lead systems, posterior positioning of leads in the right ventricle lowers VDFTs appreciably. Furthermore, a septal location of leads resulted in lower VDFTs than free-wall positioning. Increasing the number of leads, and thus the effective lead surface area in the right ventricle also resulted in lower VDFTs. However, the lead configuration that resulted in the lowest VDFTs is a combination of a mid-cavity right ventricle lead and a mid-cavity left ventricle lead. The addition of a left ventricular lead resulted in a reduction in the size of the low gradient regions and a change of its location from the left ventricular free wall to the septal wall.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Carfax Publishing, Taylor & Francis Ltd
    Addiction 94 (1999), S. 0 
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims. To examine whether male-female differences in rates of drug use could be traced back to differences in rates of exposure to initial opportunities to try drugs, rather than to sex differences in the probability of making a transition to use, once opportunity has occurred. Design. Cross-sectional sample survey research with nationally representative samples and retrospective assessments. Setting. United States, 1979-94. Participants. Respondents were 131 226 residents aged 12 years and older, recruited for the National Household Surveys on Drug Abuse by multi-stage probability sampling at nine time points. Measurements. Estimated proportion of males and females with an opportunity to use marijuana, cocaine, hallucinogens and heroin; proportions reporting use among those having an opportunity to use each drug; proportion making a "rapid transition" from initial opportunity to initial use. Findings. For each survey year, males were more likely than females to have an initial opportunity to use drugs. However, few male-female differences were observed in the probability of making a transition into drug use, once an opportunity had occurred. Conclusions. Previously documented male excess in rates of drug use may be due to greater male exposure to opportunities to try drugs, rather than to greater chance of progressing from initial opportunity to actual use. This suggestes that sex differences in drug involvement emerge early in the process. Implications of these findings are discussed in relation to the epidemiology and prevention of drug use, and future research on sex differences in drug involvement.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Psychology 50 (1999), S. 305-331 
    ISSN: 0066-4308
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Psychology
    Notes: Abstract In this review we focus on the perceptual and psychophysical aspects of somesthesis, although some information on neurophysiological aspects will be included as well; we look primarily at studies that have appeared since 1988. In the section on touch, we cover peripheral sensory mechanisms and several topics related to spatial and temporal pattern perception, specifically measures of spatial sensitivity, texture perception with particular emphasis on perceived roughness, complex spatial-temporal patterns, and the use of touch as a possible channel of communication. Other topics under this section include the effects of attention on processing tactile stimuli, cortical mechanisms, and the effects of aging on sensitivity. We also deal with thermal sensitivity and some aspects of haptics and kinesthesis. In the section on pain, we review work on the gate-control theory, sensory fibers, and higher neural organization. In addition, studies on central neurochemical effects and psychophysics of pain are examined.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mefenamic acid (MFA) has anti-convulsant and pro-convulsant effects in vivo, and has been shown to potentiate and inhibit GABAA (γ-aminobutyric acid) receptors in vitro. In this study, whole-cell currents were recorded from Xenopus oocytes and human embryonic kidney (HEK) cells expressing human recombinant GABAA receptors to resolve the molecular mechanisms by which MFA modulates GABAA receptor function. We demonstrate that MFA potentiated GABA-activated currents for α1β2 γ2S (EC50 = 3.2 ± 0.5 μm), but not for α1β1 γ2S receptors. MFA also enhanced GABA-activated responses and directly activated α1β2/β3 GABAA receptors, but inhibited responses to GABA on α1β1 constructs (IC50 = 40 ± 7.2 μm). A comparison of β1, β2 and β3 subunits suggested that the positive modulatory action of MFA involved asparagine (N) 290 in the second transmembrane domain (TM2) of the β2 and β3 subunits. Mutation of N290 to serine (S) markedly reduced modulation by MFA in α1β2(N290S)γ2S receptors, whereas α1β1(S290N)γ2S constructs revealed potentiated responses to GABA (EC50 = 7.8 ± 1.7 μm) and direct activation by MFA. The potentiation by MFA displayed voltage sensitivity. The direct activation, potentiation and inhibitory aspects of MFA action were predominantly conferred by the β subunits as the spontaneously active homomeric β1 and β3 receptors were susceptible to modulation by MFA. Molecular comparisons of MFA, loreclezole and etomidate, agents which exhibit similar selectivity for GABAA receptors, revealed their ability to adopt similar structural conformations. This study indicates that N290 in TM2 of β2 and β3 subunits is important for the regulation of GABAA receptor function by MFA. Our data provide a potential molecular mechanism for the complex central effects of MFA in vivo.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of esthetic and restorative dentistry 11 (1999), S. 0 
    ISSN: 1708-8240
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Purpose: The purpose of this longitudinal whitening study was to determine the stability, post-treatment side effects, and patient satisfaction after 6 months of active treatment of tetracycline-stained teeth with 10% carbamide peroxide at 0 and 54 months post treatment. Materials and Methods: Twelve patients who completed the study (80%) were contacted and asked to participate in a survey concerning their whitening experience. Subjects were asked whether there had been any change in the shade of their teeth after treatment, and if they had experienced any side effects that they believed were treatment-related. Eight of the twelve patients underwent clinical examination. Results: Ten patients (83%) reported no obvious shade change or only a slight darkening not noticed by others. Two (17%) reported a slight darkening that is probably noticeable by other people, but no one reported moderate darkening or significant darkening back to original shade. All respondents (n = 12) denied having to have a crown or root canal that they believed was treatment-related. Examiners who compared preoperative and post-treatment photographs and Vita shade values were in agreement with the patients' perceptions of shade change. The degree of improvement was significant for both the immediate (0 mo) and the 54-month post-treatment comparison with the pretreatment shade (p 〈 .005 and p 〈 .01 respectively).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York : Cambridge University Press
    Church history 68 (1999), S. 1065-1066 
    ISSN: 0009-6407
    Source: Cambridge Journals Digital Archives
    Topics: History , Theology and Religious Studies
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York : Cambridge University Press
    Church history 68 (1999), S. 187-188 
    ISSN: 0009-6407
    Source: Cambridge Journals Digital Archives
    Topics: History , Theology and Religious Studies
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiac surgery 14 (1999), S. 0 
    ISSN: 1540-8191
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background and purpose: Minimally invasive coronary artery bypass grafting (CABG) has been facilitated by the introduction of the Octopus Tissue Stabilization system (OTS). OTS improves exposure immobilizing the heart with minimal hemodynamic effects allowing multivessels off cardiopulmonary bypass (CPB) CABG. The purpose of this study was to compare the utilization and clinical outcome of the OTS in three geographically distinct centers. Methods: 239 patients who underwent OTS-CABG at Allegheny University Hospital/Medical College of Pennsylvania, Harrisburg Hospital, and Park Nicollet Clinic/HealthSystem Minnesota were reviewed. Age, acuity of patients, and number and type of vessels bypassed were recorded. Complications, mortality, length of hospital stay, incidence of conversion to CPB and blood transfusions, and operating room costs were compared to risk matched control patients who underwent CPB CABG during the same period. Results: Results were similar in all three centers. The average age was 62.3 years. Emergent operation was necessary in 7%-10% of patients, the operations averaged 1.8 graftdpatient. Arteries bypassed were LAD, DIAG, OM, RCA, PDA, and RPLB. There were 96% of operations completed without CPB. Morbidity was low (12%). Atrial fibrillation and blood transfusion rate were decreased. Mortality was 0 compared with a predicted mortality of 1.6%. Hospital length of stay was shorter and operating room costs were 61% lower. Conclusions: OTS provides predictable reproducible immobilization allowing the performance of single and multiple off-pump CABG to almost all coronary branches with minimal morbidity and decreased costs in a variety of patients. Similar findings from three different centers suggests that these results are easily reproducible. (J Card Surg 1999; 14:323–329)
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...