ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
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
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Composite instrumentation amplifier for biopotentials (1990)
    Springer
    Annals of biomedical engineering 18 (1990), S. 251-262 
    Details
    ISSN: 1573-9686
    Keywords: Biopotential amplifiers ; Differential amplifiers ; Composite amplifiers ; Common mode rejection ratio ; Interference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We present the design of an instrumentation biopotential amplifier that, (a) combines the ac coupling and high input impedance of an ac-coupled buffer with the CMRR of a simple differential amplifier or a monolithic instrumentation amplifier, (b) improves the CMRR by using a potentiometer without requiring either precision resistors or high-CMRR op amps, (c) illustrates how to calculate the CMRR for differential-input stages for either differential output or single-ended output. With our approach, for the 741 op amp, the CMRR of the differential stage exceeds 126 dB at 10 Hz and 106 dB at 100 Hz, which is higher than the 90 dB of the op amp alone. This is because a potentiometer permits mismatch of the resistor ratio, which compensates for the low CMRR of the op amp. Use of the LF355 op amp, which has a wider bandwidth, yields a CMRR of 126 dB at both 10 and 100 Hz. If the second stage is an instrumentation amplifier then no adjustment is necessary. Mismatch of passive components in the bootstrapped input buffer stage decreases the CMRR from 126 dB to 112 dB at 60 Hz and decreases it further at lower frequencies, but that is not a problem for the usual power-line interference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368441
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Errors in four-electrode impedance plethysmography (1983)
    Springer
    Medical & biological engineering & computing 21 (1983), S. 674-680 
    Details
    ISSN: 1741-0444
    Keywords: Impedance plethysmography ; Instrumentation errors ; Plethysmography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The errors in electrical impedance plethysmography are not well known. In the paper errors due to inadequate instrumentation, improper electrode application, and physiological changes have been analysed. Minimum electrical requirements for a general purpose four-electrode instrument are: (a) input impedance of voltage-sensing circuit+4 kΩ; (b) output impedance of constant-current source+20 kΩ; (c) c.m.r.r.+400; (d) common-mode input impedance+40 kΩ; and (e) apparent change of resistance due to noise×0·5 mΩ. All electrodes should be separated by at least one limb diameter. Changes of electrode impedance due to pressure produce negligible error in a four-electrode configuration. The only way to eliminate the large subject-motion errors is to eliminate the motion. Changes of blood resistivity with velocity produce an error estimated at 10 per cent. A repeatability test on the upper arm gave a standard deviation of 6 per cent of the mean.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02464029
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Design, implementation and evaluation of amicrocomputer-based portable arrhythmia monitor (1984)
    Springer
    Medical & biological engineering & computing 22 (1984), S. 151-159 
    Details
    ISSN: 1741-0444
    Keywords: Alarm ; Arrhythmia ; ECG ; Microcomputer ; Monitor ; Real-time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The design of a portable, battery-operated microcomputer-based monitor for ambulatory ECG recording and analysis is described. Designed for real-time cardiac arrhythmia analysis, it is suitable for use on ambulator, patients for several weeks, and is about the size and weight of a Holter recorder. The device differs from a Holter recorder in that is does not store normal complexes but recognises and alarms on significant arrhythmias. It sotres 16 s of the arrhythmic event, which it can transmit by telephone to a central receiving station for immediate appraisal by a cardiologist. The monitor uses a CMOS microcomputer and has 2kbytes of program memory and 2kbytes of data memory. The arrhythmia monitor program recognises tachycardia, bradycardia, asystole, dropped beats, and PVCs. The alarm limits are physician programmable. The performance of the monitor was evaluated with standard annotated ECG tapes provided by MIT/BIH. This device should be useful for applications such as antiarrhythmic drug studies, for pacemaker and postsurgery evaluations, and for detecting premonitory as well as life-threatening arrhythmias.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446819
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...