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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 129 (1999), S. 362-368 
    ISSN: 1432-1106
    Keywords: Key words Binocular ; Monocular ; Disparity ; Vergence ; One-handed catching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The aim of this study was to examine the role of binocular and monocular information sources in specifying time-to-contact. More specifically, it was investigated whether the timing of the one-handed catch is consistent with a binocular tau-function strategy. Subjects (n=8) were required to time their grasp to catch a ball approaching with a constant spatial trajectory. The ball approached at three different constant velocities (1.5, 2.0 and 2.5 m/s). Vergence and disparity were manipulated through subjects wearing a telestereoscope to increase the effective interocular separation, under both binocular and monocular viewing. Subjects performed 24 trials in each of the four conditions. Subjects’ started the opening of the hand earlier in the binocular telestereoscope condition when a ball approached with velocity of 1.5 m/s. They then closed the hand earlier in the binocular telestereoscope condition at all ball approach velocities. There were no effects of telestereoscope on the timing of hand opening and closing under monocular viewing. This finding suggests the use of the binocular information in timing the grasp. However, there were effects of approach velocity under all conditions of monocular and binocular viewing. Subjects’ closed the hand earlier as a function of increasing approach velocity. Together, the effects of the telestereoscope and approach velocity indicate that timing of the one-handed catch is not consistent with the use of a binocular ”tau-function” variable. Rather, it is concluded that multiple sources of monocular and binocular information contribute to the regulation of timing.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 129 (1999), S. 369-377 
    ISSN: 1432-1106
    Keywords: Key words Adaptation ; Selection ; Re-calibration ; Timing ; One-handed catching ; Binocular information
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract   A pre-exposure, exposure, post-exposure design was used to assess the adaptation of the timing of a one-handed catch during telestereoscopic viewing. More specifically, it was examined whether the adaptation involved: (1) ignoring binocular sources of information and selecting other information, or (2) a recalibration of the coupling between the effected binocular information and the catching movement, and (3), if it is recalibration, whether it is restricted to the manipulated binocular information. To test these hypotheses, subjects (n=16) were assigned to one of two groups, each group performing three blocks of 15 trials in the dark with only the ball visible. In the exposure condition, both groups were required to catch balls under binocular telestereoscopic viewing. In the pre-exposure and post-exposure conditions, subjects performed under binocular and monocular viewing, respectively. Kinematics of the grasping movement were recorded. It was predicted that, in the case of a selection process, no afterfeffects would occur in the post-exposure condition, whereas, in the case of recalibration, aftereffects would occur. Moreover, if the recalibration is restricted to the manipulated information, only the group that was provided with binocular vision during the pre- exposure and post-exposure conditions would show aftereffects. Significant condition (pre-exposure, exposure, post-exposure) by block (first three trials, last three trials) effects were found for the moments of grasp onset, peak opening velocity and hand closure, indicating that the hand was opened and closed earlier in the first three trials of telestereoscopic viewing. This coincided with an increase in catching failures. In addition, for the moments of hand closure and peak closing velocity, negative aftereffects were found in the post-exposure condition. The hand was closed later in the first three trials after removal of telestereoscope. With respect to the presence of the aftereffects, no differences were found between the groups. It was concluded that adaptation to telestereoscopic viewing in the timing of a one-handed catch is due to the recalibration of the coupling between information and movement, rather than a selection of another source of information. Moreover, it is likely that the recalibration was not restricted to the single, manipulated information. Rather, the recalibration involves multiple binocular and monocular optical and oculomotor sources of information.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1041
    Keywords: Dopamine ; renal function ; renal blood flow ; glomerular filtration rate ; reserve capacity ; elderly ; low protein diet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The aims of this study were to determine the effects of dopamine and a low protein diet on glomerular filtration rate and effective renal plasma flow in the aged kidney. Effective renal plasma flow was measured using 125I-labelled hippuran and glomerular filtration rate using 51Cr-labelled EDTA. Low-dose continuous intravenous dopamine 3 μg·kg−1·min−1 in 10 healthy elderly volunteers caused a significant increase in effective renal plasma flow but not in the mean glomerular filtration rate when compared with baseline. However, glomerular filtration rate did increase substantially in 5 subjects (mean 14.4, SD 1.3). This implied that the elderly kidney was working maximally without reserve capacity in half the elderly. Since renal function is likely to be even more reduced in elderly patients with congestive cardiac failure, dopamine infusions may have little place in this condition in some older patients. A low protein diet (0.69 g·kg−1) in the same volunteers reduced glomerular filtration rate, suggesting that protein restriction may help to reduce the increased filtration rate in the remaining nephrons, thereby leading to structural and functional preservation in the aged kidney.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 47 (1992), S. 0 
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 19 (1992), S. 0 
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. During the 1989 National Heart Foundation Risk Factor Prevalence Survey a subsample in Hobart collected 24 h urine samples to measure electrolyte excretion.2. The ranges were 30-344 mmol/24 h for Na+ excretion (mean 160 mmol/24 h for men, 124 mmol/24 h for women), and 25-119 mmol/24 h for K+ excretion (mean 77 mmol/24 h for men, 68 mmol/24 h for women).3. As in other surveys, women excreted about 20–25% less Na+ and K+ than men, although there was no significant sex difference in the ratio of Na+/K+ excretion.4. The recommended dietary intake (RDI) for Na+ and K+ was followed simultaneously by 19% of subjects, and 13% had a 24 h urinary Na+/K+ ratio ≤ 1.0.5. Observance of the RDI limited the value of iodized salt for goitre prophylaxis.6. Sodium excretion rates were outside the therapeutic range of thiazide diuretics in 22% of subjects.7. Diet groups for long-term prospective cohort studies to test the prophylactic value of avoiding salt could apparently be recruited from existing subsamples of the population.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Tissue responses in Plectropomus leopardus gills infested with Dissonus manteri copepodid and ehalimus larvae were almost entirely proliferative, with little or no cellular infiltration. The pathological changes were related to attachment, feeding and parasite size, and comprised progressive mechanical erosion, epithelial hyperplasia and fibrosis. When present, infiltrating cells were associated with initial attachment by the copepodid and with the frontal filament basal plate. Approximately 2.4% of the respiratory area was lost as a result of direct vascular damage. Disruption of branchial blood flow resulted from the burrowing and feeding activities of the larvae and compression of adjacent vessels as the parasite increased in size. Chalimus stages were attached by a frontal filament which consisted of a stem with a terminal anchor, and a basal plate in contact with the cartilaginous filament ray. Following chalimus release, the branchial tissue appeared to repair rapidly. No frontal filament remains were found.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1874-1876 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The stability of homogeneously pumped single-section laser diodes is analyzed theoretically and it is found that under certain bias conditions negative gain suppression factor laser diodes (NGSFLDs) self-pulsate. An analytical condition for self-pulsation in homogeneously pumped single-section laser diodes is derived. The dynamics of self-pulsating NGSFLDs under direct modulation are analyzed and a quasiperiodic route to chaos is found. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 42 (1995), S. 0 
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Detailed measurements of flow velocity and its turbulent fluctuation were obtained over fixed, two-dimensional dunes in a laboratory channel. Laser Doppler anemometry was used to measure the downstream and vertical components of velocity at more than 1800 points over one dune wavelength. The density of the sampling grid allowed construction of a unique set of contour maps for all mean flow and turbulence parameters, which are assessed using higher moment measures and quadrant analysis. These flow field maps illustrate that: (1) the time-averaged downstream and vertical velocities agree well with previous studies of quasi-equilibrium flow over fixed and mobile bedforms and show a remarkable symmetry from crest to crest; (2) the maximum root-mean-square (RMS) of the downstream velocity values occur at and just downstream of flow reattachment and within the flow separation cell; (3) the maximum vertical RMS values occur within and above the zone of flow separation along the shear layer and this zone advects and diffuses downstream, extending almost to the next crest; (4) positive downstream skewness values occur within the separation cell, whereas positive vertical skewness values are restricted to the shear layer; (5) the highest Reynolds stresses are located within the zone of flow separation and along the shear layer; (6) high-magnitude, high-frequency quadrant-2 events (‘ejections’) are concentrated along the shear layer (Kelvin-Helmholtz instabilities) and dominate the contribution to the local Reynolds stress; and (7) high-magnitude, high-frequency quadrant-4 events occur bounding the separation zone, near reattachment and close to the dune crest, and are significant contributors to the local Reynolds stress at each location. These data demonstrate that the turbulence structure associated with dunes is controlled intrinsically by the formation, magnitude and downstream extent of the flow separation zone and resultant shear layer. Furthermore, the origin of dune-related macroturbulence lies in the dynamics of the shear layer rather than classical turbulent boundary layer bursting. The fluid dynamic distinction between dunes and ripples is reasoned to be linked to the velocity differential across the shear layer and hence the magnitude of the Kelvin-Helmholtz instabilities, which are both greater for dunes than ripples. These instabilities control the local flow and turbulence structure and dictate the modes of sediment entrainment and their transport rates.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of epidemiology 6 (1990), S. 40-44 
    ISSN: 1573-7284
    Keywords: Leptospires ; Antibody persistence ; West Indies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Participants in a survey for leptospiral agglutinating antibodies undertaken in Trinidad, West Indies, in 1977–78, were further monitored for up to 5-and-a-half years. 52 individuals with a titre ≥ 1:400 were matched for age, sex and occupation with seronegative subjects. They were re-bled twice (on average 2.38 and 4.84 years later), and changes of titre were noted. At the first follow-up, 78% of negative controls remained negative, and 22%, showed titre changes. Among the seropositive subjects, 47% showed a fall in titre, 38% showed no change, and in 15% the titre rose. New exposure rates between the original and first follow-up samples were 96/1,000 survey population per year in the controls, and 68/1,000 for the subjects with titres 〉 1:400. Between the first and second followup, 47% of the seropositive subjects lost titre, 40% showed no change, and 13% showed a rise in titre. These data demonstrate that although antibody titres may be maintained for a few years at the same level, or show a loss as is usually expected, about 8.3% of individuals in Trinidad may be infected/reinfected per year. The infection/reinfection rate is an important factor in the epidemiology of leptospirosis.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 1511-1513 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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