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Biomedical subjects

R Frahm

Publications and source records attributed to R Frahm.

At least 19 recordsLinked to original sources
PubMed2004

Solar wind-induced atmospheric erosion at Mars: first results from ASPERA-3 on Mars Express.

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the martian topside atmosphere to solar wind plasma forcing. The low-altitude penetration of solar wind plasma and the energization of ionospheric plasma may be due to solar wind irregularities or perturbations, to magnetic anomalies at Mars, or both.

Journal Article↗
PubMed2004

[Imaging diagnostics of ulnar wrist pain].

An exact knowledge of the value of different pictorial diagnostic techniques allows a focussed and rapid diagnosis of ulnar wrist pain. A prerequisite for the choice of the best possible method of investigation is an exact clinical examination. The basic examination involves conventional recording at both the centralised at the symptomatic levels. If there is a suspicion of occult bone lesion, finely focused, magnified graphics, CT or bone scintigraphy should be used, depending on both the problem faced and availability. For tissue or ligament lesions, stress graphics, movement studies or MRT, also with contrast media, should be used. Bone scintigraphy is a suitable method to differentiate between inflammatory tissue and/or bone changes.

Arthralgia↗
PubMed2001

XAFS investigations of tin nitrides.

Tin nitrides (Sn3N4) prepared by the reaction of Sn-halides with KNH2 in liquid ammonia and a subsequent vacuum annealing procedure were investigated with transmission mode XAFS experiments. While the near edge data suggest the presence of a univalent Sn-compound with a valency close to +4, the analysis of the extended X-ray absorption fine structure proves the presence of two different local Sn sites in this crystal structure: While Sn(1) is surrounded by 4 nitrogen in a distance of 2.06 A, each Sn(2) ion is coordinated with 6 nitrogen at about 2.17 A radial distance.

Journal Article↗
PubMed2001

Piezo-QEXAFS: advances in time-resolved X-ray absorption spectroscopy.

The Piezo-QEXAFS technique is a novel tool for time-resolved X-ray absorption spectroscopy in the hard X-ray range. Monochromator components consisting of specialized tilt stages to perform fast energy scans, lightweight crystal holders, bending mechanics, and control electronics are being installed and commissioned. It is planned to perform fast EXAFS scans with time resolution in the millisecond range. With Piezo-QEXAFS all typical X-ray absorption experiments will be possible as it retains the standard linear geometry. The achieved time resolution opens interesting insights into the dynamics of phase transitions and chemical reactions.

Journal Article↗
PubMed2001

Reflection mode XAFS investigations of reactively sputtered thin films.

Amorphous Ta-oxide and Sn-nitride thin films were prepared by reactive sputter deposition on smooth float glass substrates and investigated ex situ using reflection mode XAFS. The absorption coefficient mu and its fine structure were extracted from the measured reflection mode XAFS spectra with a method based on the Kramers-Kronig transform. Bond distances, coordination numbers and Debye-Waller factors were determined by a detailed XAFS data analysis and compared to those of reference compounds. In addition, changes of the atomic short range order of the sputter deposited Ta2O5-films induced by a thermal heat treatment in ambient air were examined as a function of the annealing temperature.

Journal Article↗
PubMed2001

Piezo-QEXAFS with fluorescence detection: fast time-resolved investigations of dilute specimens.

First X-ray absorption spectroscopy experiments with a vibrating piezo-driven double-crystal monochromator (piezo-QEXAFS) and fluorescence detection are reported. It is shown that high-quality XANES spectra can be recorded on a time scale of about 50 ms per spectrum, even for very low concentrations of < 10 mmol l-1 using fluorescence detection. The quality of the spectra, possible applications, as well as present limits of the technique will be discussed.

Metals↗
PubMed1993

[Intra- and postpartum cortisol concentrations during fentanyl anesthesia].

In a clinical study the course of cortisol concentration in serum was investigated at the following points: under labour, directly post partum simultaneously in the mother, the umbilical artery and vein and on the first and second day after birth in the mother and on the second third days in the newborn. Two groups of patients were investigated: 51 first and multiple parturients with peridural fentanyl analgesia for labour pain relief (PFA) and 42 first and multiple parturients as control group. The reduction of stress under PFA could be confirmed by measurement of cortisol concentrations in serum. The cortisol concentrations listed according to the time of day showed significantly lower values for the multiple parturients compared with the control group. Circadian peaks of the intrapartal cortisol in serum are generally absent in the multiple parturients. In the first parturients of the PFA group a more differentiated course of the cortisol levels listed according to the time of the day was observed. Up to about noon, the cortisol values are markedly lower than those of the control group, but after decreasing tendency in the early afternoon, they show another peak around 4.00 p.m. This means there is still a circadian rhythm under the influence of PFA for the first parturients. In contrast to the multiple parturients, the reaction of the cortisol level of the first parturients after PFA is only of short duration. At the other measuring points there are possibly different stress factors such as permanent expectation under labour and the absence of labour experience, superposing the fentanyl effect seen in the cortisol levels of the multiple parturients.

Analgesia, Epidural↗
PubMed1992

[Computerized tomography diagnosis of scaphoid fracture and pseudarthrosis in comparison with roentgen image].

Twenty eight patients with fourteen acute scaphoid fractures and fourteen with scaphoid non-union were examined with standard X-rays in two planes, special scaphoid projections and computed tomography. Nine scaphoid fractures were revealed by both standard X-rays and CT, whereas four fractures could only be detected by CT. Computed tomography should be used when there is clinical suspicion of scaphoid fracture but standard radiographs remain negative. All carpal bones should be examined. Fourteen patients with suspected scaphoid non-union were examined. In twelve patients, scaphoid non-union seemed to be complete in standard X-rays, whereas CT showed a bony bridge between the proximal and distal fragment. Another patient showed bony union. Two patients showed no non-union in standard X-rays. One was confirmed after a Matti-Russe procedure, but the bone graft was dislocated, causing restricted wrist motion. One scaphoid non-union was demonstrated by CT. Two patients showed signs of additional carpal fractures. Diagnostic applications of CT for scaphoid non-union include the determination of the exact location of the fragments and the evaluation of post-traumatic cysts, thus simplifying pre-operative planning.

Adult↗
PubMed1991

[Computed tomography of the superior and inferior ankle joint].

Computed tomography of the tibotalar and subtaler joints in standardised planes produces comparable images irrespective of examiners. Traumatic, degenerative or neoplastic lesions of the joint surfaces are shown without superimposition. Intraosseous changes can be localised exactly in relation to the joint. Assessment of possible fractures in children is simplified by simultaneous imaging of soft tissues and bone. Diagnosis of traumatic lesions of ligaments or tendons and dislocation of tendons by bone fragments is possible only on CT-images. After injection of air loose intra-articular bodies can be recognised much more satisfactorily with computed tomography than with conventional arthrography.

Ankle Injuries↗
PubMed1991

[Hypersupination dislocation of the distal radio-ulnar joint after distal radius fracture].

Following an intraarticular distal radius fracture of the scaphoid, scapholunate dissociation and fracture of the ulnar styloid process without dislocation, the distal radius fracture healed with rotational deformity. In the course of conservative treatment, a dislocation of the distal radioulnar joint in locked hypersupination developed. Due to the locked rotational deformity, standard X-rays were difficult to assess. Only with the help of a CAT-scan, were the authors able to visualize the distal radioulnar joint dislocation and later control the postoperative result.

Adult↗