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Biomedical subjects

B Pons

Publications and source records attributed to B Pons.

9 recordsLinked to original sources
PubMed2005

Investigation of laser-irradiated Ar cluster dynamics from K-shell x-ray emission measurements.

Intense (up to a few 10(17) W/ cm2) femtosecond (down to 40 fs) laser pulses are focused onto a partially clusterized argon gas jet. The target was previously characterized and optimized in order to get a homogeneous and dense jet of clusters with a well controlled size. The interaction leads to x-ray emission that is absolutely calibrated and spectrally resolved using a high resolution time-integrated spectrometer in the K-shell range (from 2.9 to 4.3 keV). X-ray spectra are investigated as a function of different laser temporal parameters such as the nanosecond prepulse contrast, the laser pulse duration, and the femtosecond delay between two different laser pulses. The cluster size ranges from 180 to 350 angstroms and irradiation by laser pulses with both linear and circular polarization is investigated. The experimental results are discussed in terms of the laser-cluster interaction dynamics. They are compared with the predictions of collision-dominated nanoplasma models. However, further interaction processes are required in order to explain the observed characteristic lines demonstrating highly charged ions up to Ar16+.

Journal Article↗
PubMed2004

[Gastroparesis on a gastric ulcer].

INTRODUCTION: Gastroparesis is the failure of the stomach to empty because of decreased gastric motility. It's a fairly frequent medical problem. Diabetes is the most common known cause. OBSERVATION: The first case report is that of an 82 year-old woman, in whom acute gastric distension occurred, evoking a gastric volvulus on the scan. Upper endoscopy revealed gastric ulcers. All symptoms disappeared with medical treatment. The second case report concerns a 37 year-old man who was admitted with signs of occlusion. CT scans revealed acute gastric distension. Emergency surgery revealed no gastric volvulus. Upper endoscopy revealed gastritis and numerous ulcers. The signs regressed with medical treatment. DISCUSSION: Our observations are original in their -pseudo-surgical discovery. Acute gastric distension is rare, but must be recognised because of the risk of perforation and rupture of the stomach walls. These case reports are also original in their aetiology. Gastric ulcers are rarely described in this situation. CONCLUSION; Gastroparesis is a frequent situation but potentially severe. A review of the principle signs, aetiology and treatment is made.

Acute Disease↗
PubMed2000

Monocentric close-coupling expansion to provide ejected electron distributions for ionization In atomic collisions

A new monocentric close-coupling expansion, in terms of spherical Bessel functions confined in a finite box, is presented and implemented for &pmacr;+H(1s) collisions. Besides total ionization cross sections, this method also provides reliable ejected electron distributions, which are beyond the scope of usual close-coupling expansions and basically confirm the recent classical description of Illescas and Riera [Phys. Rev. Lett. 80, 3029 (1998)].

Journal Article↗
PubMed1999

Effects of smoking on local delivery of controlled-release doxycycline as compared to scaling and root planing.

This paper examines the effects of smoking on the treatment outcomes of two nonsurgical therapies: (1) scaling and root planing alone (SRP) or (2) controlled-release of subgingivally delivered doxycycline hyclate in a polylactic acid based polymer gel. Subjects from 2 9-month multicenter studies were classified as nonsmokers (never smoked: 100 subjects), former smokers (137 subjects), and current smokers (> or = 10 cigarettes/day: 121 subjects). Clinical parameters were analyzed for treated sites with baseline probing depths > or = 5 mm and for a subset of treated sites with baseline probing depths of > or = 7 mm. Clinical parameters (plaque levels, clinical attachment levels, pocket depths, and bleeding on probing) were analyzed at baseline, 4, 6, and 9 months. In the doxycycline treated group in general, there were neither marked significant differences in clinical attachment gain nor differences in probing depth reduction among the 3 smoking groups. On the other hand, in the scaling and root planing treated group in general, there were significant differences in clinical attachment gain and pocket depth reduction, with non-smokers responding better than former smokers and current smokers at 6 and 9 months. These differences in clinical response between scaling and root planing alone versus controlled-release of locally-delivered doxycycline hyclate among these 3 smoking groups are discussed in relation to treatment implications for smokers.

Administration, Topical↗
PubMed1998

Speciation of ionic alkyllead compounds in human urine by gas chromatography-mass spectrometry after butylation through a Grignard reaction.

One analytical procedure for the determination of ionic alkyllead in human urine has been studied. The system consists of the extraction of Me3Pb+, Et3Pb+ and Pb2+ at pH 9.0 with diethyldithiocarbamate to an organic phase. Then, the ionic compounds are butylated with BuMgCl and the final organic solution is analyzed by GC-MS-SIM. The elimination of both foam and gels in the extraction step and the general procedure for the urine are discussed. The recovery of compounds ranges from 105.1% for Me3Pb+ to 97.2% for Et3Pb+ using hexane as extracting agent and detection limits are 18.4 pg/ml of Me3Pb+ and 19.2 pg/ml of Et3Pb+ in urine. The speciation of ionic alkylleads in the urine of a petrol station worker showed a value of 27.9 pg/ml of Me3Pb+ in urine and Et3Pb+ was below the detection limit.

Ethanol↗