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Biomedical subjects

B Geyer

Publications and source records attributed to B Geyer.

14 recordsLinked to original sources
PubMed2006

Comment on "temperature dependence of the Casimir effect".

Recently, Brevik [Phys. Rev. E, 71, 056101 (2005)] adduced arguments against the traditional approach to the thermal Casimir force between real metals and in favor of one of the alternative approaches. The latter assume zero contribution from the transverse electric mode at zero frequency in qualitative disagreement with unity as given by the thermal quantum field theory for ideal metals. Those authors claim that their approach is consistent with experiments as well as with thermodynamics. We demonstrate that these conclusions are incorrect. We show specifically that their results are contradicted by four recent experiments and also violate the third law of thermodynamics (the Nernst heat theorem).

Comment↗
PubMed2000

Casimir force at both nonzero temperature and finite conductivity.

We find the combined effect of nonzero temperature and finite conductivity onto the Casimir force between real metals. Configurations of two parallel plates and a sphere (lens) above a plate are considered. Perturbation theory in two parameters (the relative temperature and the relative penetration depth of zero-point oscillations into the metal) is developed. Perturbative results are compared with computations. Recent improper computations based on the Lifshitz formula for the temperature Casimir force are discussed.

Journal Article↗
PubMed1998

High-Temperature In Situ Straining Experiments in the High-Voltage Electron Microscope.

: Design rules are described here for high-temperature straining stages for transmission electron microscopy. Temperatures above 1000 degreesC can be attained by electron bombardment of the specimen grips. Thermal equilibrium can be reached in a short time by carrying off the heat by water cooling. Some applications of this stage are described. Ferroelastic deformation was observed at 1150 degreesC in t' and partially stabilized zirconia, which changes the microstructure for successive dislocation plasticity. In the oxide-dispersion-strengthened alloy INCOLOY MA 956, dislocations are impeded by oxide particles and move smoothly between the particles. At high temperatures, both the resting and traveling times control the average dislocation velocity. In MoSi2 single crystals of a soft orientation, dislocations with 1/2<111> Burgers vectors are created in localized sources and move on {110} planes in a viscous manner. The dislocations in Al-Pd-Mn single quasicrystals are oriented in preferred crystallographic directions and move in a viscous way as well. On the basis of in situ observations, conclusions are drawn for interpreting macroscopic deformation behavior at high temperatures.

Journal Article↗
PubMed1996

[Ultrasonic studies in reptiles].

Ultrasonography in reptiles is a safe, noninvasive repeatable diagnostic imagine method. Size, volume and inner structure of organs can easily be determined. Based on 460 ultrasonographic examinations in 8 species of terrapins, 12 species of snakes and 22 species of lizard normal appearance of heart, gonads, fat bodies, kidneys, bladder and gastrointestinal tract are described. Pathological findings are explained in details using examples.

Animals↗
PubMed1989

[Orthopedic treatment of regular dorsal and dorsolumbar hyperkyphosis. New principles of active correction].

The orthopaedic treatment of hyper-kyphosis should not be unique. If the principles of treatment are different in relation with the thoracic or thoraco-lumbar localisation of the apex of the deformity, it is necessary to distinguish for the middle thoracic curve two types of patients: these in whom the kyphosis and the lordosis are balanced (the cast must diminish the lumbar lordosis and the imbalanced posterior types with a great kyphotic curve and a short compensatory lordosis which is important not to be diminish by the treatment. The principles of plaster casting are described in the two types; emphasizing on the unlucky aspect of the sternal support in the middle thoracic kyphosis and in the necessity of the thoracic modification if we wish to obtain a good result. The active expiratory reeducation is capital before and during the treatment.

Casts, Surgical↗
PubMed1985

PKU.

Explore the source record for details and available documents.

Counseling↗
PubMed1973

Myelin from human peripheral nerves. Quantitative and qualitative studies in two age groups.

Myelin in femoral nerve segments obtained at autopsy was isolated quantitatively by a series of discontinuous and continuous flotation procedures. The total amount of myelin isolated from these nerves was expressed as the sum of cholesterol, glycolipid, phospholipid, and protein and averaged 2.6+/-0.4 mg/g in a group aged 60-77 yr compared with 10.8+/-1.9 mg/g of nerve in a group aged 35-58 yr. The lower value in the older group remained apparent whether the myelin content was related to the whole nerve segment, its unit length or weight. This indicates that the decrease is an absolute one, not related to a change with aging in the nonmyelin content of nerve. No qualitative differences in myelin lipids were found between the two groups. Protein content was, however, significantly higher in the older group (34 and 28.7% of the total myelin weight, respectively). The decrease in myelin content with aging, observed by direct measurement in this study, may be the structural counterpart to age related alterations in peripheral nerve function-decreased conduction velocity, and impaired appreciation of vibration.

Adult↗
PubMed1971

Studies of brain myelin in the "quaking mouse".

Myelin was isolated from the brains of "quaking" and littermate control animals and its composition was determined. The brains of quaking animals contained approximately one-fourth as much myelin as the control animals. There were qualitative as well as quantitative differences between the myelin from the two groups. By continuous cesium chloride gradient flotation it was shown that the myelin from the quaking animals consisted solely of a band corresponding to the heavier and smaller of the two bands found in normal controls. Cholesterol and glycolipids were lower and phospholipids (mainly phosphatidylcholine) and protein were higher in quaking animals than in controls. Also, phosphatidal-ethanolamine was decreased, and several consistent differences in the fatty acids (both unsubstituted and hydroxy) and aldehydes of the component lipids were found. In general there were smaller amounts of monounsaturated fatty acids in quaking animals. We suggest from these findings that myelin in the quaking mouse has certain compositional similarities with juvenile myelin, but it may be an abnormal type of myelin.

Animals↗