1,285 research outputs found
Nucleon-Nucleon Scattering in a Harmonic Potential
The discrete energy-eigenvalues of two nucleons interacting with a
finite-range nuclear force and confined to a harmonic potential are used to
numerically reconstruct the free-space scattering phase shifts. The extracted
phase shifts are compared to those obtained from the exact continuum scattering
solution and agree within the uncertainties of the calculations. Our results
suggest that it might be possible to determine the amplitudes for the
scattering of complex systems, such as n-d, n-t or n-alpha, from the
energy-eigenvalues confined to finite volumes using ab-initio bound-state
techniques.Comment: 19 pages, 13 figure
Follow-up of a suspected excess of brain tumours among Namibian children
The original publication is available at http://www.samj.org.zaTo the Editor: The aim of this follow-up study was to further
investigate a suggested excess of childhood brain tumours
(CBT) among Herero children in Namibia from 1983 to 1988. Incidence rates of primary brain tumours among Herero
children were found to be 4 times higher than rates among
Namibian children in any of the 10 other tribal groups or
among children of European origin.
The causes of CBTs remain largely unknown. The only
established causes are ionizing radiation and predisposing
inherited syndromes. A particularly compelling hypothesis is
that exposure during gestation to N-nitroso compounds
(NOCs) may lead to the development of CBT. This hypothesis
was suggested by experimental work in which 100%
production of nervous system (NS) tumours in rat offspring
resulted from transplacental exposure to the neurocarcinogen
ethylnitrosourea (ENU) or to low levels of the precursor
compounds sodium nitrite and ethyl urea added to the food
and drinking water of pregnant rat
- …