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P Froelich

Publications and source records attributed to P Froelich.

17 recordsLinked to original sources
PubMed2000

Collisions between metastable hydrogen atoms at thermal energies

The complex interaction potentials arising in the approach of two metastable hydrogen 2s atoms are calculated and the cross sections for ionization, excitation transfer, and elastic scattering are predicted. The measured cross section for associative ionization at E = 4.1 meV equals 2x10(-15) cm (2). We calculate a total ionization cross section of 2x10(-13) cm (2), varying as E(-2/3) at higher energies. Thus it appears that dissociative ionization is the major ionization channel. We find also that double excitation transfer into two excited H(2p) atoms is still more probable with the large cross section of 9x10(-12) cm (2) at E = 4.1 meV varying as E(-1/2) at higher energies. The detection of the resulting Lyman alpha photons would provide a diagnostic test of our predictions.

Journal Article↗
PubMed2000

Hydrogen-antihydrogen collisions

Matter-antimatter interactions are investigated using hydrogen-antihydrogen collisions as an example. Cross sections for elastic scattering and for the antihydrogen loss (either through the rearrangement reaction, resulting in formation of protonium and positronium according to H+&Hmacr;-->p&pmacr;+e(+)e(-), or via annihilation in flight) are calculated for the first time in a fully quantum mechanical approach. Implications for experiments intending to trap and cool antihydrogen are discussed.

Journal Article↗
PubMed2000

Improved molecular final-state distribution of HeT+ for the beta-decay process of T2

An improved theoretical final-state distribution of HeT+ (and HeH+) resulting from the beta decay of molecular tritium T2 (HT) is presented to accommodate the needs of increased accuracy in the analysis of ongoing and future tritium neutrino-mass experiments. The previously available theoretical spectrum has been improved in many respects, and adopted approximations have been validated.

Journal Article↗
PubMed1995

[Early manifestations of Tangier disease].

BACKGROUND: The diagnosis of Tangier disease in childhood is based on the specific aspect of tonsils or by screening relatives of affected subjects. CASE REPORT: A moderately enlarged liver associated with splenomegaly was found upon routine physical examination of a 3 month-old breast-fed boy, born in Turkey from consanguineous parents. Laboratory studies disclosed moderate increase in serum alanine aminotransferase activity (ALAT 52 UI/l, N < 30). The diagnosis of Tangier disease was confirmed by studies of plasma cholesterol and apolipoprotein A. By 8 months of age, the patient had enlarged orange tonsils. Small cervical, axillary and inguinal lymphadenopathies were present. The tonsilar and adenoidal tissues were removed at 18 months of age because the patient suffered from chronic airway obstruction. Colonoscopic examination revealed tiny flat orange spots, 1 to 2 mm in diameter, scattered throughout the rectosigmoidal and colonic mucosa. Survey of the family led to the discovery of one sister, with asymptomatic apolipoprotein Al deficiency and a normal sister, while the parents were heterozygotes for Tangier disease. CONCLUSION: Enlarged liver associated with a moderate level in serum aminotransferase may be an early manifestation of Tangier disease in infants. Rectosigmoidal and colonic lesions may be convenient for biopsy when tonsillectomy is not indicated.

Hepatomegaly↗
PubMed1981

Chronic catheterization of coronary sinus in large domestic animals.

A technique was developed for long-term catheterization of the coronary sinus in calves and ponies. A catheter with a 10 to 12 cm-long stiff segment was implanted via right lateral thoracotomy. Catheters were kept patent up to 10 weeks after the surgical procedure. At that time, location of the catheter tip was confirmed both by determining oxygen tension of the anaerobically sampled blood and by radiography. Base-line values of oxygen venous blood of non-anesthetized calves and ponies are reported.

Animals↗