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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 1141-1152 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Calorimetric, thermomechanical, and rheological properties of undercooled liquid Pd40Ni40P20 were determined within a wide temperature range above the glass transition. The concept of the limiting fictive temperature was applied to the entire set of measurements to compare the different properties adequately. It was found that an equilibrium state of a sample that is defined by its calorimetric glass temperature corresponds to a similar equilibrium state for the specific volume and for the shear viscosity as well. The Kauzmann temperature as one of the most important material characteristics concerning the glass transition could be determined with high accuracy leading to the evaluation of the free volume persistent in the samples. Viscosity values of the liquid extending over a range of about nine orders in magnitude could be described best by the free volume theory evaluated by Cohen and Grest, provided that experimentally obtained parameters were used for the calculations. The comparison between nonequilibrium measurements at isochronous heating and model calculations in the framework of bimolecular reaction kinetics shows that good agreement can be achieved using thermodynamic parameters that have been obtained from equilibrium measurements. However, systematic deviations indicate also the limitations of the model that are related to the intrinsic dynamic heterogeneity of the vitreous state. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Supersonic fluid flow and the interaction of strong shock waves to produce jets of material are ubiquitous features of inertial confinement fusion (ICF), astrophysics, and other fields of high energy-density science. The availability of large laser systems provides an opportunity to investigate such hydrodynamic systems in the laboratory, and to test their modeling by radiation hydrocodes. We describe experiments to investigate the propagation of a structured shock front within a radiation-driven target assembly, the formation of a supersonic jet of material, and the subsequent interaction of this jet with an ambient medium in which a second, ablatively driven shock wave is propagating. The density distribution within the jet, the Kelvin–Helmholz roll-up at the tip of the jet, and the jet's interaction with the counterpropagating shock are investigated by x-ray backlighting. The experiments were designed and modeled using radiation hydrocodes developed by Los Alamos National Laboratory, AWE, and Lawrence Livermore National Laboratory. The same hydrocodes are being used to model a large number of other ICF and high energy-density physics experiments. Excellent agreement between the different simulations and the experimental data is obtained, but only when the full geometry of the experiment, including both laser-heated hohlraum targets (driving the jet and counter-propagating shock), is included. The experiments were carried out at the University of Rochester's Omega laser [J. M. Soures et al., Phys. Plasmas 3, 2108 (1996)]. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1986-1988 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Modulated-temperature calorimetry measurements on the bulk glass-forming Pd40Ni40P20 alloy yielded the complex specific heat response of the deeply undercooled melt near the static glass transition. The imaginary contributions to the complex signal give direct access to the spectrum of slow α-relaxation modes of the undercooled liquid state that are frozen in upon vitrification. The results are discussed with respect to the kinetics of the glass transition and compared to results obtained from static equilibrium measurements. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 24 (2001), S. 0 
    ISSN: 1540-8159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: TAN, H.L., et al.: Adenosine Induced Ventricular Arrhythmias in the Emergency Room. While adenosine effectively terminates most supraventricular tachycardias (SVT), rare case reports have demonstrated its proarrhythmic potential, including induction of ventricular tachycardia (VT). The aim of this study was to define the proarrhythmic effects of adenosine in a large, unselected population. During a 5-year period, adenosine was used (average dose 9.7 mg) in the emergency room to manage 187 episodes of tachycardia in 127 patients. In two thirds of the cases, adenosine induced ventricular ectopy following successful termination of SVT, including premature ventricular complexes (PVC) and nonsustained VT. The adenosine induced PVCs and VT were transient and self-terminating. More than half had a right bundle branch block morphology with a superior axis that suggested an origin in the inferior left ventricular septum. In conclusion, although adenosine is commonly used in clinical practice to treat SVTs, we found that it induced PVCs and VT in two thirds of the patients. The high incidence of ventricular arrhythmias following adenosine infusion was surprising but did not require further intervention. These arrhythmias appeared to frequently originate from the inferior left ventricular septum, suggesting that this area may be particularly susceptible to the proarrhythmic effects of adenosine.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    350 Main Street , Malden , MA 02148-5018 , USA and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Pacing and clinical electrophysiology 27 (2004), S. 0 
    ISSN: 1540-8159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: There are limited data about the chronotropic capacity of the peak endocardial acceleration (PEA) sensor. This study directly compared the chronotropic function from the PEA and the activity (ACT) sensor. The study included 18 patients (age 73 ± 7 years) with ≥ 75% pacemaker-driven heart rate (HR) and a PEA sensor and 11 healthy controls (age 67 ± 7 years) underwent a chronotropic assessment exercise protocol (CAEP) exercise test with the pacemaker patients in VVIR mode after programming the sensors in the default setting with adjustment of the upper sensor rate as an age related maximum value (220-age). The ACT sensor was externally strapped on the thorax. Achieved exercise duration for the patients and controls was, respectively, 9.2 ± 3 vs 18.4 ± 4 minutes (P 〈 0.001). The maximal achieved HR with the PEA sensor was 124 ± 25 beats/min, versus the ACT with 140 ± 23, versus the controls with 153 ± 26 beats/min (P 〈 0.001 between the groups). For the PEA, ACT, and controls, the time to peak HR was, respectively, 11 ± 3, 7 ± 3.6, and 18 ± 4 (P 〈 0.001 between groups) and HR after 10 minutes recovery was, respectively, 80 ± 20, 65 ± 15, and 82 ± 4 beats/min (P 〈 0.001 between groups). The PEA sensor functions hypochonotroop during exercise programmed as a single sensor system. It is, therefore, preferable to combine the PEA sensor with an activity-based sensor in a dual sensor system. Although both groups had normal left ventricular functions, the exercise capacity of pacemaker patients is significantly lower than in the controls.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 24 (2001), S. 0 
    ISSN: 1540-8159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: ALINGS, M., et al.: Quinidine Induced Electrocardiographic Normalization in Two Patients with Bru-gada Syndrome. Two patients with Brugada syndrome are presented. The ECGs showed right precordial J waves and ST-segment elevation. Patient 1 was resuscitated from nocturnal ventricular fibrillation, patient 2 was asymptomatic. In only patient 1, flecainide was infused causing monomorphic “malignant” ventricular extrasystoles (R on T), demonstrating the deleterious effect of Class IC antiarrhythmic drugs in Brugada syndrome. However, administration of the Class Ia antiarrhythmic drug quinidine caused normalization of the ECG in both patients. Based on in vitro experiments, agents that reduce the magnitude of Ito-mediated phase 1 have been suggested to normalize ST-segment elevation in Brugada syndrome. This is the first clinical report of such a quinidine induced ECG normalization.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1365-2036
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background : Although 5-HT3 antagonists have been used to treat chemotherapy-induced emesis and diarrhoea-predominant irritable bowel syndrome, the effects of 5-HT3 agonists in humans are unknown.Aim : To determine the effect of MKC-733, a selective 5-HT3 receptor agonist, on upper gastrointestinal motility.Methods : Oral MKC-733 (0.2, 1 and 4 mg) was compared with placebo in three randomized, double-blind, cross-over studies in healthy males. Antroduodenal manometry was recorded for 8 h during fasting and 3 h post-prandially (n = 12). Gastric emptying and small intestinal transit were determined by gamma-scintigraphy (n = 16). Gastric emptying, accommodation and antral motility were determined by echoplanar magnetic resonance imaging (n = 12).Results : MKC-733 (4 mg) increased the number of migrating motor complexes recorded in the antrum and duodenum (P 〈 0.001), but had no effect on post-prandial motility. MKC-733 delayed scintigraphically assessed liquid gastric emptying (P = 0.005) and accelerated small intestinal transit (P = 0.038). Echoplanar magnetic resonance imaging confirmed the delayed gastric emptying (P 〈 0.001) and demonstrated a significant increase in cross-sectional area of the proximal stomach (P 〈 0.01).Conclusions : MKC-733 delays liquid gastric emptying in association with relaxation of the proximal stomach, stimulates fasting antroduodenal migrating motor complex activity and accelerates small intestinal transit.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 56 (2001), S. 0 
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 58 (2001), S. 0 
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Length at age 1, 2 and 3 white bass Morone chrysops in 54 Texas, U.S.A., reservoirs was related significantly to longitude and log10(TDS) (total dissolved solids). Length at age 1 also was related to morphoedaphic index (MEI), mean depth, and length of growing season. Quadratic models for latitude and growing season explained 19–24% (latitude) and 24–34% (growing season length) of the variation in length of white bass. Length of all age classes was unrelated to reservoir age, maximum depth, and surface area.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Melbourne, Australia : Blackwell Science Pty
    International journal of nursing practice 6 (2000), S. 0 
    ISSN: 1440-172X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The aim of the study was to compare two methods of data collection—personal interviews and self-administered questionnaires—with patients' evaluations of the quality of care they received. The sample consisted of 41 matched pairs of inpatients at a medical clinic. In each pair, one patient was interviewed and one responded to a questionnaire. Data were collected using the questionnaire ‘Quality from the Patients Perspective’ (QPP). The QPP consists of 54 items designed to measure the following four quality dimensions: (i) the medical–technical competence and (ii) the degree of identityorientation in the action of the caregivers; (iii) the physical–technical conditions; and (iv) the sociocultural atmosphere of the care organization. Results showed that patients who were interviewed had significantly less favourable scores on the ‘softer’ quality dimension scales—the identity-oriented approach of the caregivers and the sociocultural atmosphere of the care setting. Possible reasons for this were discussed, including the possibility that the questions designed to measure these two dimensions were more abstract and emotionally loaded than the items of the other two quality dimensions.
    Materialart: Digitale Medien
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