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  • 1
    Electronic Resource
    Electronic Resource
    The Cyclization of 3,3-Dimethyl-5-keto-hexanoic Acid to Dimedone by Sulfuric Acid (1955)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 77 (1955), S. 6656-6658 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01629a086
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  • 2
    Electronic Resource
    Electronic Resource
    Geochemical processes affecting meltwater chemistry and the formation of saline ponds in the Victoria Valley and Bull Pass region, Antarctica (1994)
    Springer
    Hydrobiologia 281 (1994), S. 171-186 
    Details
    ISSN: 1573-5117
    Keywords: Antarctica ; Victoria Valley ; Bull Pass ; meltwater chemistry ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Major ion, trace element and nutrient concentrations have been determined in meltwater streams, frozen lakes and isolated saline ponds of the Victoria Valley and Bull Pass regions in Victoria Land, Antarctica. Geochemical processes affecting glacial meltwater composition with time and distance from the source glaciers include solute acquisition by soil salt leaching and solute concentrations by evaporation. Evaporation in the marginal lake melt and in isolated saline ponds appears to increase the Mg/Ca ratio of these meltwaters relative to that of meltwater streams. With progressive evaporation gypsum and calcite may precipitate, leading to the development of Na-Cl and Na-HCO3 brine ponds. These ponds may be vertically stratified with respect to temperature and salinity if they experience partial or complete freezing over the winter season. The chemical characteristics and nutrient concentrations of meltwaters in the Victoria Valley are similar to those of other drainage systems in the region, although the Ca-Cl brines reported from the Wright Valley immediately to the south were not observed. Trace element (Cu, Pb, Zn, Cd, Mn and Fe) concentrations measured in the lakes and large ponds do not show any evidence of unusual enrichment in the drainage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028680
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  • 3
    Electronic Resource
    Electronic Resource
    Analogue multiplexer for use with an f.m. tape recorder (1978)
    Springer
    Medical & biological engineering & computing 16 (1978), S. 569-572 
    Details
    ISSN: 1741-0444
    Keywords: Analogue multiplexer ; Frequency-division multiplexing ; F.M. tape recorder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommarie Un dispositif multiplexeur diviseur de fréquences stocke deux signaux d'EEG sur chaque, voie d'un enregistreur à bande f.m. Nous avons utilisé un magnétophone à bande à 14 voies du commerce tournant à la vitesse de 4·75 cm/s, pour stocker 20 signaux de donnée ayant une réponse en fréquence de 0·3 à 45 Hz. Nous pourrions élargir le système en mettant deux signaux de donnée sur chaque voie du magnétophone sauf une, qui enregistrerait la fréquence porteuse.
    Abstract: Zusammenfassung Ein f.d.m.a.-system speichert auf jedem Kanal eines FM-Tonbandgeräts zwei e.e.g.-Datensignale. Wir benutzten ein 14-kanäliges Industrie-Tonbandgerät mit einer Laufgeschwindigkeit von 1-7/8 Zoll/Min zur Speicherung von 20 Datensignalen mit einem Frequenzgang von 0·3 bis 45 Hz. Wir können das System so erweitern, daß zwei Datensignale auf jedem Tonbandkanal geleitet werden außer einem, der den Trägeroszillator aufnimmt.
    Notes: Abstract A frequency-division multiplexing system stores two e.e.g. data signals on each channel of an f.m. tape recorder. We have used a 14-channel commercial tape recorder running at 1 7/8 in/s to store 20 data signals having a frequency response from 0·3 to 45 Hz. We could expand the system to put two data signals on every tape recorder channel except one, which records the carrier oscillator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457811
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  • 4
    Electronic Resource
    Electronic Resource
    Electrode studies for the long-term ambulatory ECG (1985)
    Springer
    Medical & biological engineering & computing 23 (1985), S. 116-121 
    Details
    ISSN: 1741-0444
    Keywords: Adhesion ; Artefact ; ECG ; Electrodes ; Evaluation ; Irritation ; Location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Noise and motion artefacts interfere with ambulatory ECG recording. In the paper the hypothesis that proper skin preparation and electrode design and placement could reduce the artefact levels is tested. The comparison of four commercial electrodes shows differences in adhesive strength and levels of skin irritation but does not indicate significant differences in the artefact levels produced by the electrodes. Four treatments are compared—no skin preparation, rubbing with alcohol, abrasion and puncturing—for their effectiveness in reducing motion artefact. Skin preparations do not reduce the motion artefact significantly but cause much discomfort. Therefore, skin preparation is not recommended. We recorded the signal (QRS complex) to-noise (artefact at the electrode site) ratio at 15 thoracic locations and recommend two pairs for ambulatory ECG recording. The statistical experimental design procedures used can also be adopted for comparison and testing for improvement of other electrode properties and designs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456747
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  • 5
    Electronic Resource
    Electronic Resource
    Analogue computer model of a kidney during preservation (1979)
    Springer
    Medical & biological engineering & computing 17 (1979), S. 199-206 
    Details
    ISSN: 1741-0444
    Keywords: Modelling ; Analogue computer ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This report describes a model of the renal perfusion dynamic changes that occur during kidney preservation. The model utilises data from physiological experiments performed in this laboratory as well as from observations reported in the literature. Included in the model are the effects of cellular volume changes due to metabolic variations, vascular distensibility and a hypothesised tissue pressure effect observed under some conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02440929
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  • 6
    Electronic Resource
    Electronic Resource
    Heart rate recorder (1979)
    Springer
    Medical & biological engineering & computing 17 (1979), S. 719-723 
    Details
    ISSN: 1741-0444
    Keywords: Activity monitoring ; Energy consumption ; Heart monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract We describe the design of an instrument that can acquire and store the average heart rate of a subject over 256 time intervals of predetermined length (1 or 6 min) during normal daily activities. The instrument consists of two units: a portable recorder, worn by the patient, detects and counts heart beats, and stores their average in memory, and a display later retrieves the contents of that memory. C.M.O.S. technology and programmable operational amplifiers resulted in low power consumption (20 mW). The results obtained from this instrument were accurate to about 1 beat/min compared with Holter monitoring and telemetry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441552
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  • 7
    Electronic Resource
    Electronic Resource
    Simple design for an impedance plethysmograph (1982)
    Springer
    Medical & biological engineering & computing 20 (1982), S. 461-465 
    Details
    ISSN: 1741-0444
    Keywords: Impedance plethysmography ; Plethysmography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A simple and inexpensive impedance plethysmography has been designed. Complete circuit diagrams are provided to facilitate system replication. The operation of each functional unit in the measurement system is described. Particular attention is given to the demodulation chip, which simplifies circuit design and increases measurement performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442407
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  • 8
    Electronic Resource
    Electronic Resource
    Design and evaluation of QRS and noise detectors for ambulatory e.c.g. monitors (1982)
    Springer
    Medical & biological engineering & computing 20 (1982), S. 709-714 
    Details
    ISSN: 1741-0444
    Keywords: Arrhythmia ; Detectors ; Filters ; Monitors ; Noise ; QRS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In ambulatory e.c.g. monitoring, a high level of noise results in false QRS detection. We present a compact low-powered QRS detector design. We present a noise detector circuit that identifies most false QRS detections so that it can disable alarms. We present a standardised exercise protocol for testing the QRS detector. Data collected from subjects bending forward (for baseline drift), lifting a weight (for e.m.g.), and jogging (for motion artefact) present a realistic test set for an ambulatory QRS detector. We observe error rates of the order of 1%, the noise detector identifies more than half of these. These techniques should reduce false alarms in arrhythmia monitoring systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442525
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  • 9
    Electronic Resource
    Electronic Resource
    Contribution of different sized vessels in the extremities to the arterial pulse waveform as recorded by electrical impedance and volume plethysmography (1985)
    Springer
    Medical & biological engineering & computing 23 (1985), S. 155-164 
    Details
    ISSN: 1741-0444
    Keywords: impedance plethysmography ; Microcirculation ; Modelling ; Volume plethysmography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The plethysmographic signal (either volume or electrical impedance) obtained from a limb segment has contributions due to volume change contributions from the arteries, veins and smaller blood vessels. The electrical impedance plethysmograph signal contains, in addition, contributions due to blood resistivity changes in all these vessels. Uncertainty exists as to the relative contributions of different vessels. We have modelled the leg circulation in detail, with more than 80 simultaneous differential equations, to determine the pressure and flow in different sized vessels and hence their contribution to the impedance and volume plethysmograph signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02456753
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  • 10
    Electronic Resource
    Electronic Resource
    Thermal—electrical finite element modelling for radio frequency cardiac ablation: Effects of changes in myocardial properties (2000)
    Springer
    Medical & biological engineering & computing 38 (2000), S. 562-568 
    Details
    ISSN: 1741-0444
    Keywords: Finite element ; RF ablation ; Cardiac ablation ; Temperature-controlled ; Power-controlled ; Bio-heat equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Finite element (FE) analysis has been utilised as a numerical tool to determine the temperature distribution in studies of radio frequency (RF) cardiac ablation. However, non of the previous FE analyses clarified such computational aspects as software requirements, computation time or convergence test. In addition, myocardial properties included in the previous models vary greatly. A process of FE modelling of a system that included blood, myocardium, and an ablation catheter with a thermistor embedded at the tip is described. The bio-heat equation is solved to determine the temperature distribution in myocardium using a commercial soft-ware application (ABAQUS). A Cauchy convergence test (∈=0.1°C) was performed and it is concluded that the optimal number of elements for the proposed system is 24610. The effects of changes in myocardial properties (±50% electric conductivity, +100%/−50% thermal conductivity, and +100%/−50% specific heat capacity) in both power-controlled (PCRFA) and temperature-controlled RF ablation (TCRFA) were studied. Changes in myocardial properties affect the results of the FE analyses of PCRFA more than those of TCRFA, and the maximum changes in lesion volumes were −58.6% (−50% electric conductivity), −60.7% (+100% thermal conductivity), and +43.2% (−50% specific heat).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02345754
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