PubMed Health⌕ Search

Biomedical subjects

S T Thompson

Publications and source records attributed to S T Thompson.

At least 19 recordsLinked to original sources
PubMed2005

Ultracold molecule production via a resonant oscillating magnetic field.

A novel atom-molecule conversion technique has been investigated. Ultracold 85Rb atoms sitting in a dc magnetic field near the 155 G Feshbach resonance are associated by applying a small sinusoidal oscillation to the magnetic field. There is resonant atom to molecule conversion when the modulation frequency closely matches the molecular binding energy. We observe that the atom to molecule conversion efficiency depends strongly on the frequency, amplitude, and duration of the applied modulation and on the phase space density of the sample. This technique offers high conversion efficiencies without the necessity of crossing or closely approaching the Feshbach resonance and allows precise spectroscopic measurements. Efficiencies of 55% have been observed for pure Bose-Einstein condensates.

Journal Article↗
PubMed2005

Production efficiency of ultracold feshbach molecules in bosonic and fermionic systems.

We investigate the production efficiency of ultracold molecules in bosonic 85Rb and fermionic 40K when the magnetic field is swept across a Feshbach resonance. For adiabatic sweeps of the magnetic field, our novel model shows that the conversion efficiency of both species is solely determined by the phase space density of the atomic cloud, in contrast with a number of theoretical predictions. In the nonadiabatic regime our measurements of the 85Rb molecule conversion efficiency follow a Landau-Zener model.

Journal Article↗
PubMed2005

Spontaneous dissociation of 85Rb Feshbach molecules.

The spontaneous dissociation of 85Rb dimers in the highest lying vibrational level has been observed in the vicinity of the Feshbach resonance that was used to produce them. The molecular lifetime shows a strong dependence on magnetic field, varying by 3 orders of magnitude between 155.5 G and 162.2 G. Our measurements are in good agreement with theoretical predictions in which molecular dissociation is driven by inelastic spin relaxation. Molecule lifetimes of tens of milliseconds can be achieved within approximately a 1 G wide region directly above the Feshbach resonance.

Journal Article↗
PubMed2002

Microscopic dynamics in a strongly interacting Bose-Einstein condensate.

An initially stable 85Rb Bose-Einstein condensate (BEC) was subjected to a carefully controlled magnetic field pulse near a Feshbach resonance. This pulse probed the strongly interacting regime for the BEC, with the diluteness parameter (na(3)) ranging from 0.01 to 0.5. Condensate number loss resulted from the pulse, and for triangular pulses shorter than 1 ms, decreasing the pulse length actually increased the loss, until very short time scales (approximately 10 micros) were reached. The observed time dependence is very different from that expected in traditional inelastic loss processes, suggesting the presence of new microscopic BEC physics.

Journal Article↗
PubMed1996

Continuous passive motion use in hand therapy.

This paper discusses the indications and contraindications of continuous passive motion (CPM) in hand therapy. The pros and cons of portable and stationary CPMs available for the hand, wrist, forearm, elbow, and shoulders are reviewed.

Elbow Joint↗
PubMed1996

Early motion after wrist surgery.

This article reviews general considerations for therapists when initiating early motion after wrist surgery. Various early range of motion techniques and splinting are discussed in detail for the radiocarpal joint and distal radioulnar joint.

Humans↗
PubMed1995

Extensor physiology in the hand and wrist.

The Physiology of finger extension is complex because of the various components of the extensor tendon mechanism. This article discusses the role each component plays in finger extension. Tendon excursion, strength, and electromyographic activity of the extensors are discussed.

Finger Joint↗
PubMed1994

Prevention of male infertility: an update.

Initial evaluation of the infertile male includes a diligent search for testicular factors, gonadotoxins, and coital factors in order to identify existing causes of impaired fertility and prevent further diminution in fertility. Certain prophylactic measures can prevent future infertility such as prompt correction of cryptorchidism, testicular torsion, genital infection, and adolescent varicocele, and proper precautions to limit occupational, medical, and recreational gonadotoxins.

Humans↗
PubMed1993

Preventable causes of male infertility.

The initial evaluation of the infertile man includes a diligent search for testicular factors, gonadotoxins, and coital factors so as to identify existing causes of impaired fertility and to prevent further dimunition in fertility. There are also prophylactic measures in the treatment of all men that can prevent future infertility, such as prompt correction of cryptorchidism, testicular torsion, genital infection, and adolescent varicocele and proper precautions to limit occupational, medical, and recreational gonadotoxins.

Agricultural Workers' Diseases↗
PubMed1992

Delayed spontaneous rupture of an ileocolonic neobladder.

A case of delayed spontaneous rupture of an ileocolonic neobladder and subsequent peritonitis 4 years after the initial operation is reported. Many of the features of this case are similar to those noted in recent reports of spontaneous rupture of an augmented bladder and it is postulated that the etiology is the same.

Colon↗
PubMed1987

Infectious complications of penile prosthetic implants.

An infectious complication involving placement of a penile prosthesis is a disastrous event. A review of more than 300 devices placed between 1979 and 1984 at this center reveals an infectious complication rate of 8.3 per cent. Perioperative risk factors predisposing to infection included reoperation for technical failures, inadequate antibiotic coverage (specifically for Staphylococcus epidermidis), failure to perform a circumcision at the time of placement in uncircumcised patients and simultaneous placement with an artificial urinary sphincter device. No group of patients nor type of prosthesis was more susceptible to the development of a postoperative infection.

Anti-Bacterial Agents↗
PubMed1984

Patterns in the distribution of REM sleep in normal human sleep.

Results are reported of four analyses of the distribution of REM sleep across nights of two subjects who slept for 50 consecutive nights on a regimented, but normal, sleep schedule. We found (a) a strong phase-setting effect of sleep onset on the distribution of REM sleep within nights, (b) no systematic change in the phase of the distribution of REM sleep across nights, and (c) a relationship between the nocturnal temperature minimum and the distribution of REM sleep within nights. Our results are consistent with the notion that the nightly distribution of REM sleep may be determined by an oscillatory process, the phase of which is reset at sleep onset, but which may be subject to other influences, such as the circadian temperature rhythm. These results are in general agreement with those found by investigators studying subjects on free-running or other abnormal sleep schedules.

Adolescent↗
PubMed1984

Selective medium for Pseudomonas cepacia containing 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan and polymyxin B sulfate.

Contamination of solutions and lotions with Pseudomonas cepacia is a growing concern among health professionals. The identification of P. cepacia usually requires a long series of biochemical tests. In an effort to develop a more direct method, we evaluated plate count agar containing 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan and polymyxin B sulfate at respective concentrations of 1 and 75 micrograms/ml as a medium for selectively isolating P. cepacia. The medium inhibited the growth of all gram-negative bacilli and gram-positive cocci tested except P. cepacia and Serratia marcescens. These two microorganisms could easily be differentiated by their colony morphology and their reactions in the oxidase test. When nonsterilized water samples were inoculated with P. cepacia and spread or streaked on the selective medium, all P. cepacia organisms were recovered. These results demonstrate the usefulness of 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan and polymyxin B sulfate in the detection of P. cepacia. We believe that this selective medium could be useful in isolating P. cepacia from mixed bacterial flora that might be present in environmental water and water-related samples, such as solutions and lotions.

Acridines↗
PubMed1979

Activation of Thermus phosphofructokinase by monovalent cations.

The presence of the monovalent cations Tl+, NH+4, K+, Rb+ or Cs+, in decreasing order of potency, produce a marked equivalent increase in the specific enzyme activity of phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) purified from extreme thermophile, Thermus X-1. By contrast, the monovalent cations Li+, Na+ or CH3NH+3 produce no detectable catalyitic activation at concentrations up to 100 mM. The relative potency of these cations suggests that each polypeptide chain in the tetrameric enzyme possesses a cationbinding site having tetragonal symmetry and that the protein ligands are principally hydroxyl or carboxylate oxygens. Only the enzyme-cation complex and not the enzyme by itself exhibits cooperativity with respect to the dependence of catalytic rate on the concentration of the substrate, fructose 6-phosphate. In the presence of subsaturating but not saturating concentrations of substrate, the catalytic activation produced by monovalent cations is also cooperative. Exclusion chromatographic measurements indicate that the enzyme remains tetrameric at catalytic concentrations in the presence or absence of an activating monovalent cation.

Catalysis↗
PubMed1979

Purification of a cyclic nucleotide phosphodiesterase from bovine brain using blue dextran-Sepharose chromatography.

The soluble high Km form of cyclic nucleotide phosphodiesterase (EC 3.4.1.17) was purified over 2000-fold from bovine brain homogenates principally using blue dextran-Sepharose chromatography. The purified protein has a specific enzymic activity of 167 units/mg and appears homogeneous when examined by polyacrylamide gel electrophoresis. The enzyme has a molecular weight of 1.26 +/- 0.05 x 10(5) consisting of two apparently identical polypeptide chains. Kinetic measurements indicate that the substrates cyclic GMP and cyclic AMP each have a single Km value, 9 +/- 1 micron and 150 +/- 50 micron, respectively, that the two cyclic nucleotides compete for the same catalytic site, that the blue dye of blue dextran-Sepharose is a competitive inhibitor for the cyclic nucleotides, and that the Vmax with cyclic AMP as substrate is about an order of magnitude larger than that for cyclic GMP. Bovine brain calmodulin stimulates the catalytic rate of the purified enzyme in the presence of Ca2+ by increasing the Vmax associated with each cyclic nucleotide substrate.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1976

Binding of Cibacron blue F3GA to proteins containing the dinucleotide fold.

A simple, convenient, and sensitive spectrophotometric procedure is described for quantitative measurement of nucleoside phosphate binding sites constructed by the dinucleotide fold. The procedure involves difference spectral titration of such enzymes with the dye Cibacron blue F3GA in a spectral region remote from the intrinsic absorbance of proteins or natural ligands. The titration curves can be analyzed to determine the affinity of nucleoside phosphate binding sites for both the dye and the natural ligand over a potentially wide range of experimental conditions. The interaction of the dye with two proteins which contain the dinucleotide fold, lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) and phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3), is illustrated.

Adenosine Triphosphate↗