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  • 1
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In recent Petawatt laser experiments at Lawrence Livermore National Laboratory, several hundred joules of 1 μm laser light in 0.5–5.0-ps pulses with intensities up to 3×1020 W cm−2 were incident on solid targets and produced a strongly relativistic interaction. The energy content, spectra, and angular patterns of the photon, electron, and ion radiations have all been diagnosed in a number of ways, including several novel (to laser physics) nuclear activation techniques. About 40%–50% of the laser energy is converted to broadly beamed hot electrons. Their beam centroid direction varies from shot to shot, but the resulting bremsstrahlung beam has a consistent width. Extraordinarily luminous ion beams (primarily protons) almost precisely normal to the rear of various targets are seen—up to 3×1013 protons with kTion∼several MeV representing ∼6% of the laser energy. Ion energies up to at least 55 MeV are observed. The ions appear to originate from the rear target surfaces. The edge of the ion beam is very sharp, and collimation increases with ion energy. At the highest energies, a narrow feature appears in the ion spectra, and the apparent size of the emitting spot is smaller than the full back surface area. Any ion emission from the front of the targets is much less than from the rear and is not sharply beamed. The hot electrons generate a Debye sheath with electrostatic fields of order MV per micron, which apparently accelerate the ions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 11 (2000), S. 0 
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Accessory AV Node. We report an accessory AV node producing ventricular preexcitation and comprising the retrograde limb of AV reentrant tachycardia (AVRT). A 66-year-old man presented with an anteroseptal myocardial infarction and thereafter developed recurrent, drug-refractory AVRT requiring multiple cardioversions. Electrophysiologic findings were typical for a concealed anteroseptal accessory pathway 0.5 cm anterior to the His bundle. The patient died of intractable heart failure after endocardial resection for a left ventricular aneurysm and coronary bypass grafting. Pathologic examination revealed a para-Hisian accessory AV node connecting the right atrium to ventricular myocardium immediately anterior to the His bundle at a depth of 4 mm from the endocardium. No typical AV accessory pathway was found. This is the first report of an accessory AV node that participated in AVRT. It was deeper than typical radiofrequency catheter ablation lesions.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Amiodarone Effect on Defibrillation Energy Requirement. Introduction: The effect of oral amiodarone therapy on defibrillation energy requirements in patients with an implantable defibrillator has not been established. Methods and Results: Twenty-one consecutive patients with implantable biphasic waveform defibrillators underwent a step-down determination of the defibrillation energy requirement 211 ± 12 days before and 73 ± 22 days after initiation of amiodarone therapy (mean total dose 26.7 ± 11.1 g). Serum amiodarone and desethylamiodarone concentrations were measured at the time of defibrillation energy requirement determination. The mean defibrillation energy requirement before amiodarone therapy was 9.9 ± 4.6 J. After initiation of amiodarone therapy, the mean defibrillation energy requirement increased to 13.7 ± 5.6 J (P = 0.004). A linear relationship between the amiodarone (P = 0.02, r = 0.6), desethylamiodarone (P = 0.02, r = 0.6), and combined amiodarone-desethylamiodarone concentrations (P = 0.001, r = 0.6) and the defibrillation energy requirement was noted. Stepwise regression analysis demonstrated that the combined amiodarone-desethylamiodarone concentration was the only independent predictor of increase in the defibrillation energy requirement. Conclusion: Chronic oral amiodarone therapy increases the defibrillation energy requirement by approximately 62% in patients with an implantable defibrillator. The combined amiodarone-desethylamiodarone concentration is directly related to the increase in the defibrillation energy requirement.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1540-8183
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To identify predictors of Palmaz-Schatz in-stent restenosis and determine outcomes of treatment, we assessed 6–month outcomes in 402 patients who had coronary intervention with stent placement; 60 (15%) developed angiographic and clinical evidence of restenosis. Predictors of restenosis included family history of cardiovascular disease, prior bypass surgery, nonelective stenting, stenting of a vein graft, and multiple stents. Of 60 patients with stent restenosis, 47 had repeat percutaneous intervention and 10 had bypass surgery; only 1 of these 10 patients developed symptoms requiring repeat revascularization. Of the 47 with repeat percutaneous intervention, 32 (68%) had conventional balloon angioplasty; the others had perfusion balloon catheters, laser ablation, and repeat coronary stenting. During follow-up, 22 (47%) of these 47 patients suffered recurrent angina, myocardial infarction, or death. A third revascularization procedure was performed in 14 (30%), including 5 referred for bypass. This study shows the limitations of percutaneous modalities for patients with Palmaz-Schatz in-stem restenosis. Such patients are likely to have recurrent symptoms and to undergo repeat target-vessel revascularization.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 25 (2000), S. 0 
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Dermatoses affecting the skin around stoma sites are common and difficult to treat. We have investigated the effectiveness of topical sucralfate in the management of peristomal dermatoses in adults using an open study design. Apart from forming a physical barrier to further irritation, sucralfate binds to basic fibroblast growth factor preventing its degradation and thereby promotes healing. In eight out of nine patients with faecal or urine erosions, daily, topical sucralfate treatment was associated with healing within 4 weeks. There was limited or no response to treatment in a further nine patients with traumatic ulcers, excoriated dermatitis or pyoderma gangrenosum. Topical sucralfate represents a safe, inexpensive and effective therapeutic intervention, particularly for those patients with high output or short stomas where repeated stoma leakage may be unavoidable.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6719-6721 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new series of Sm(CowFevCuxZry)z alloys has been developed to produce magnets with high intrinsic coercivity iHc at high temperatures for use up to 550 °C. The maximum use temperature is defined as TM, which is the maximum temperature at which the extrinsic demagnetization curve is a straight line. An important feature of the alloys with high TM is a lower temperature coefficient of iHc, β. These magnets have a higher resistance to demagnetization from increasing thermal agitation which occurs with increasing temperature. A study on magnetic pinning field Hp, which will be explained in the text, vs TM was conducted by measuring the initial magnetization curves of the magnets at 25 and 300 °C. The study shows that as TM increases, Hp increase at high temperatures. At 25 °C, all magnets with TM from 250 to 550 °C have Hp higher than 24 kOe, which is too high to be determined using a hysteresigraph. At 300 °C, the magnet with TM=250 °C has Hp=7.0 kOe, and the magnet with TM=550 °C has Hp=15.1 kOe. Higher pinning field at high temperatures (≥300 °C) provides a greater resistance to thermal demagnetization, which leads to better performance at high temperatures. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Boston, USA and Oxford, UK : Blackwell Publishers Inc
    Journal of personality 68 (2000), S. 0 
    ISSN: 1467-6494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Psychology
    Notes: We examined the extent to which 11- to 12-year-old children' (N= 174) self-esteem (SE) stability and level related to their perceptions of various aspects of parent-child communication. Compared to children with stable SE, children with unstable SE reported that their fathers were more critical and psychologically controlling, and less likely to acknowledge their positive behaviors or to show their approval in value-affirming ways. Likewise, children with low SE reported that their fathers exhibited these qualities to a greater extent than did children with high SE. In addition, fathers of children with stable high SE were viewed as especially good at problem solving. Children' SE level related to perceptions of mothers' communication styles very similarly to how it did with fathers'; with respect to SE stability, however, relationships were generally less consistent and frequently absent. Discussion centered on the role of parent-child communication in promoting unstable SE.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Carfax Publishing, Taylor & Francis Ltd
    Addiction 95 (2000), S. 0 
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims: To assess the effectiveness of exercise-based interventions in smoking cessation. Design: A systematic review was conducted of articles published between 1980 and 1999. The review focused on randomized controlled trials (RCTs) in which the specific effects of exercise on smoking abstinence were examined. The primary dependent variable was smoking abstinence. Other studies which had both exercise programming as an independent variable and smoking behaviour as a dependent variable are briefly discussed. Participants: The review included interventions targeting both healthy individuals and those with specific medical conditions. Settings: The interventions were delivered in both community and inpatient settings. Measurements: Information extracted from each article included details of the participants, exercise and smoking cessation programmes, control conditions, exercise adherence rates, length of follow-up and outcomes. Findings: Of the eight trials satisfying our inclusion criteria, only two trials found a positive effect for exercise on smoking abstinence. The others showed no effect. Conclusions: There is some evidence for exercise aiding smoking cessation. Of the two trials finding a positive effect one was rigorously designed, the other was found to have numerous methodological limitations. Trials showing no effect lacked sensitivity. This was principally because of small sample sizes and inadequate measurement and control of exercise adherence. There is a need for more rigorously designed studies in this area.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 5488-5498 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Beginning with the molecular-based Fokker–Planck equation obtained previously [M. H. Peters, J. Chem. Phys. 110, 528 (1999); J. Stat. Phys. 94, 557 (1999)], the Smoluchowski diffusion equation is derived here to describe the spatial and orientational dynamics of molecularly structured macromolecules near molecularly structured surfaces. The formal scaling and perturbation methods employed allow the establishment of definite limits on the use of the Smoluchowski equation when surfaces are present. It is shown that the Smoluchowski equation reduces to that given previously [D. W. Condiff and J. S. Dahler, J. Chem. Phys. 44, 3988 (1966)] in the absence of external surfaces. A specific example application is given involving a spherical macromolecule with electrostatic charge segments near a planar surface with an arbitrary charge distribution. Finally, we show that the short-time solution to the Smoluchowski equation obtained here yields a Brownian dynamics method consistent with that given previously [E. Dickinson, S. A. Allison, and J. A. McCammon, J. Chem. Soc. Faraday Trans. 2 81, 591 (1985)] for orientable, interacting Brownian particles. This study has applications to problems involving site-specific adsorption of orientable, structured Brownian particles, such as association or adsorption of biological macromolecules to cellular surfaces and enzyme–substrate docking kinetics, to name a few. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The circadian clock in the hypothalamic suprachiasmatic nuclei (SCN) regulates the pattern of melatonin secretion from the pineal gland such that the duration of release reflects the length of the night. This seasonally specific endocrine cue mediates annual timing in photoperiodic mammals. The aim of this study was to investigate how changes in photoperiod influence the cyclic expression of recently identified clock gene products (mPER and mTIM) in the SCN of a highly seasonal mammal, the Siberian hamster (Phodopus sungorus). Immunocytochemical studies indicate that the abundance of both mPER1 and mPER2 (but not mTIM) in the SCN exhibits very pronounced, synchronous daily cycles, peaking approximately 12 h after lights-on. These rhythms are circadian in nature as they continue approximately under free-running conditions. Their circadian waveform is modulated by photoperiod such that the phase of peak mPER expression is prolonged under long photoperiods. mPER1 protein is also expressed in the pars tuberalis of Siberian hamsters. In hamsters adapted to long days, the expression of mPER1 is elevated at the start of the light phase. In contrast, there is no clear elevation in mPER1 levels in the pars tuberalis of hamsters held on short photoperiods. These results indicate that core elements of the circadian clockwork are sensitive to seasonal time, and that encoding and decoding of seasonal information may be mediated by the actions of these transcriptional modulators.
    Type of Medium: Electronic Resource
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