Biomedical subjects

M Köhl

Publications and source records attributed to M Köhl.

6 recordsLinked to original sources

PubMed2002

Growth of Bose-Einstein condensates from thermal vapor.

We report on a quantitative study of the growth process of (87)Rb Bose-Einstein condensates. By continuous evaporative cooling we directly control the thermal cloud from which the condensate grows. We compare the experimental data with the results of a theoretical model based on quantum kinetic theory. We find quantitative agreement with theory for the situation of strong cooling, whereas in the weak cooling regime a distinctly different behavior is found in the experiment.

Journal Article↗

PubMed2001

Measuring the temporal coherence of an atom laser beam.

We report on the measurement of the temporal coherence of an atom laser beam extracted from a (87)Rb Bose-Einstein condensate. Reflecting the beam from a potential barrier creates a standing matter wave structure. From the contrast of this interference pattern, observed by magnetic resonance imaging, we have deduced an energy width of the atom laser beam which is Fourier limited by the duration of output coupling. This gives an upper limit for temporal phase fluctuations in the Bose-Einstein condensate.

Journal Article↗

PubMed2001

Optics with an atom laser beam.

We report on the atom optical manipulation of an atom laser beam. Reflection, focusing, and its storage in a resonator are demonstrated. Precise and versatile mechanical control over an atom laser beam propagating in an inhomogeneous magnetic field is achieved by optically inducing spin flips between atomic ground states with different magnetic moment. The magnetic force acting on the atoms can thereby be effectively switched on and off. The surface of the atom optical element is determined by the resonance condition for the spin flip in the inhomogeneous magnetic field. More than 98% of the incident atom laser beam is reflected specularly.

Journal Article↗

PubMed1994

Popliteal venous aneurysm with pulmonary and paradoxical embolization.

A 31-year-old woman was admitted with recurrent pulmonary emboli. The patient subsequently developed right sided hemiplegia. A mobile left atrial mass attached to the interatrial septum was detected and paradoxical embolization was assumed to be the underlying cause of the cerebral event. Leg phlebography and B-mode ultrasonographic imaging showed that the most probable source of embolization was a right popliteal venous aneurysm containing thrombi adherent to the vein wall. The immediate treatment was restricted to full dose heparin therapy and supportive measures. Thirteen days after admission, the aneurysm was excised. Recovery was rapid and the patient was discharged for further rehabilitation with an only minimal neurological deficit 3 weeks after admission.

Adult↗

PubMed1991

[Vascular injuries as a complication of fractures, dislocations and surgical interventions].

This is a presentation of 34 patients with traumatic or intraoperative vascular injuries treated at the Rural Clinic am Plattenwald during the timeperiod from 1978 until 1988. Limb amputation was performed in three cases. Two patients died. Our goal is to show the importance in early recognition and treatment of such injuries which requires an efficient interdisciplinary cooperation between orthopedic and vascular surgeons, as well as the radiologist. The employment of angiography should be generous.

Adolescent↗

PubMed1982

The influence of oral contraceptives on the composition of bile.

The increased risk of cholelithiasis during intake of oral contraceptives may be due to estrogen-induced saturation of the bile with cholesterol. In a randomized, prospective, crossed-over double-blind study 20 healthy women after roentgenological exclusion of gall-stones received either 1.0 mg of norethindrone acetate and 50 microgram ethinyl estradiol daily - as usual in oral contraception - for 21 days with 7 days of placebo treatment in each cycle or one fifth of this hormone dose in form of a continuous daily medication. After a 4 month's treatment the medication form was crossed-over. At the beginning of the study, before the cross-over and after the study bile was collected by duodenal intubation after a 12-h fast and the lithogenic index as a measure for cholesterol saturation of the bile was determined. No correlation between the dose and the lithogenic index was demonstrated, neither in 15 women, who had used oral contraceptives before the study nor in five women without any previous hormonal contraceptives.

Adult↗