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C Fuchs

Publications and source records attributed to C Fuchs.

116 records · Page 7Linked to original sources
PubMedDate not supplied

Capacitance in ant cuticle is frequency dependent: a statistical model.

The capacitance and the electric resistance of the cuticle of the ant Cataglyphis bicolor nigra Andr é (Hymenoptera, Formicinae ) were measured. The measurements were done at the frequencies 100 Hz and 1000 Hz and at a temperature range of 27.5-45 degrees C. Inverse correlation was observed between the capacitance and the frequency, so that at the higher frequency the capacitance was lower. Thus, in some instances, at 1000 Hz the capacitance ranged between 0.49 and 2. 16nF , while at 100 Hz it ranged between 5.74 and 19. 39nF at the measured temperature range. A similar inverse correlation was detected also between the resistance and the frequency. At 1000 Hz, the resistance values in some specimens ranged between 0.166 and 0.278 M omega whereas at 100 Hz they varied between 0.342 and 0.883 M omega. At both frequencies measured there was a temperature-dependence of the capacitance and of the electric resistance. With increase in temperature there was increase in the capacitance and a decrease in the resistance. Invariably, the trend of cuticular behavior was similar under cooling as under warming, but the values differed, creating a gap (hysteresis). Under cooling the resistance values were higher and the reverse was true for the capacitance. A statistical model is offered which graphically describes the behavior of the ant cuticle (resistance and capacitance) under changes in temperature and frequency. X-ray analysis of the cuticle revealed the presence of Ca as the most prominent element. Additional elements, but less prominent were P, S and K. It also contains Fe and Zn. The finding of a correlation between the capacitance and the frequency might lead to the following conclusions: that the measured system contains polarized substances; that the measured value in each case represents a resultant of values obtained from the measurement of more than one electrical circle (and probably more than one network of electrical circles); and that possibly a combination of (a) and (b) prevails. Presumably these changes in the capacitance and resistance at different temperatures and frequencies indicate that the ant cuticle is capable of responding to changes in the physical ambience , thus promoting proper ant spatial orientation and the pursuant behavior.

Animals↗
PubMedDate not supplied

The eustachian tube muscles in otitis media. A comparison between eustachian tube muscles in healthy and inflamed ears.

The cross-sectional area of the tensor palati (TP) and levator palati (LP) muscles in the mid-portion of the Eustachian tube was measured in serially sectioned histological specimens of 35 temporal bones (TB). 17 of the TBs presented acute or secretory otitis media. The other 18 TBs showed no evidence of inflammatory disease. No significant differences were found between the mean sizes of the muscles coming from TBs with acute and secretory otitis media and of those from TBs without signs of inflammation. The cross-sectional area of the LP was found to be significantly larger than that of the TP. These results raise the question as to the actual role of the muscles' size in inflammatory middle ear disease in infants and children, and as to the role of the LP.

Acute Disease↗
PubMedDate not supplied

Divalent ions and myocardial function during cardiopulmonary by-pass (CPB). Changes of total calcium, ionized calcium, and magnesium in plasma.

In 17 patients who underwent openheart surgery with cardiopulmonary bypass using heparinized fresh blood for priming the heart-lung machine the following investigations were done: Blood samples taken at different periods of surgery were assayed for total calcium (Catot), ionized calcium (Ca++), magnesium (Mg), hemoglobin, total pasma proteins, and the acid-base-status. Considering the different kinds of cardiopulmonary bypass the patients were divided into three groups: In the first group the results ofsurgical procedure with and without hemodilution perfusion were compared. During hemodilution perfusion Catot decreased markedly whereas Ca++ remained nearly constant. In the second group the influence of different calcium concentrations of the prime solution on Catot and Ca was tested. A low calcium content of 2.8 mEq/1 lowered Catot and Ca++ to subnormal levels. In the third group results of Mg-induced cardioplegia were compared with findings during surgical procedure with anoxic cardiac arrest. A remarkable increase of magnesium at the perfusion onset could be observed. Magnesium remained within the upper level of normal range until surgery end and decreased to normal values in the postoperative stage. Since energy requirements of the arrested heart and thus the velocity of ATP-breakdown during ischemia are closely related to the Ca++ concentration of the extracellular space low plasma calcium levels are considered to be advantageous during cardiopulmonary bypass. Only at the end of partial bypass before the heart fully takes over circulating work a sufficient calcium substitution is recommended.

Adolescent↗