417 research outputs found
Biostratigraphy of the lower Burgersdorp Formation (Beaufort Group; Karoo Supergroup) of South Africa – implications for the stratigraphic ranges of early Triassic tetrapods
The Beaufort Group (Karoo Supergroup) of South Africa comprises a thick sequence of fluvio-lacustrine sedimentary rocks that
accumulated in a landlocked, intracratonic foreland basin in southwestern Gondwana during the Middle Permian to Middle Triassic. To
the south this basin was bounded by the Cape Fold Belt, which acted as the major source of both sediment and discharge. Rocks of the
Beaufort Group are renowned for their rich fossil record and eight tetrapod-based biozones are currently recognized. The uppermost
two biozones of the Beaufort Group, the Lystrosaurus and Cynognathus assemblage zones, record terrestrial biotic recovery following the
Permo-Triassic mass extinction event. Stratigraphic overlap between these biozones occurs in the proximal sector, but their separation
by an unconformity in the distal sector reflects the incomplete preservation of the sequence in this part of the basin. Our results afford
chronostratographic control that impacts on current theories on the development of the Karoo Basin, and on the relative age of the
sequence.South African Council for Geoscience, the University of the Witwatersrand and the National Research Foundation
Ouerbegeleidingsbehoeftes ten aansien van die fisiek-gestremde voorskoolse kind as voorbereiding vir 'n insluitende onderwysomgewing
This article focuses on parents' educational needs concerning their physically disabled pre-school child with the view to placement in an inclusive learning environment. Support services include, among other things, preparation of these children to enter an inclusive learning environment, and parent education to reach this goal. Therefore parent education with a view to promoting the success of inclusion is of utmost importance, by focusing on those skills needed by physcially disabled children to perform sucessfully in the inclusive classroom milieu. The goal of parent education is to mediate those skills necessary to become an integral part of regular classroom activities and be accepted within the inclusive learning environment ; to facilitate a functional family life and educational atmosphere as basis for further growth ; to promote the least restrictive educational environment at home ; to facilitate modeling of socially acceptable behaviour patterns ; to promote a cognitively, emotionally, and socially stimulating learning environment at home ; to provide interpersonal interaction with nonhandicapped siblings and peers; and to remove stereotypes and stigmata attached to physically disabled children and to facilitate successful adjustment within the inclusive learning environment and the broader community during adulthood.
(South African Journal of Education: 2002 22(4): 338-344
The Cryogenic Target for the G Experiment at Jefferson Lab
A cryogenic horizontal single loop target has been designed, built, tested
and operated for the G experiment in Hall C at Jefferson Lab. The target
cell is 20 cm long, the loop volume is 6.5 l and the target operates with the
cryogenic pump fully immersed in the fluid. The target has been designed to
operate at 30 Hz rotational pump speed with either liquid hydrogen or liquid
deuterium. The high power heat exchanger is able to remove 1000 W of heat from
the liquid hydrogen, while the nominal electron beam with current of 40 A
and energy of 3 GeV deposits about 320 W of heat into the liquid. The increase
in the systematic uncertainty due to the liquid hydrogen target is negligible
on the scale of a parity violation experiment. The global normalized yield
reduction for 40 A beam is about 1.5 % and the target density fluctuations
contribute less than 238 ppm (parts per million) to the total asymmetry width,
typically about 1200 ppm, in a Q bin.Comment: 27 pages, 14 figure
No evidence of an 11.16 MeV 2+ state in 12C
An experiment using the 11B(3He,d)12C reaction was performed at iThemba LABS
at an incident energy of 44 MeV and analyzed with a high energy-resolution
magnetic spectrometer, to re-investigate states in 12C published in 1971. The
original investigation reported the existence of an 11.16 MeV state in 12C that
displays a 2+ nature. In the present experiment data were acquired at
laboratory angles of 25-, 30- and 35- degrees, to be as close to the c.m.
angles of the original measurements where the clearest signature of such a
state was observed. These new low background measurements revealed no evidence
of the previously reported state at 11.16 MeV in 12C
Second T = 3/2 state in B and the isobaric multiplet mass equation
Recent high-precision mass measurements and shell model calculations~[Phys.
Rev. Lett. {\bf 108}, 212501 (2012)] have challenged a longstanding explanation
for the requirement of a cubic isobaric multiplet mass equation for the lowest
isospin quartet. The conclusions relied upon the choice of the
excitation energy for the second state in B, which had two
conflicting measurements prior to this work. We remeasured the energy of the
state using the reaction and significantly disagree
with the most recent measurement. Our result supports the contention that
continuum coupling in the most proton-rich member of the quartet is not the
predominant reason for the large cubic term required for nuclei
Relativistic predictions of exclusive analyzing powers at an incident energy of 202 MeV
Within the framework of the relativistic distorted wave impulse approximation
(DWIA), we investigate the sensitivity of the analyzing power - for exclusive
proton knockout from the 3s, 2d and 2d states in
Pb, at an incident laboratory kinetic energy of 202 MeV, and for
coincident coplanar scattering angles (, ) - to
different distorting optical potentials, finite-range (FR) versus zero-range
(ZR) approximations to the DWIA, as well as medium-modified coupling constants
and meson masses. Results are also compared to the nonrelativistic DWIA
predictions based on the Schr\"{o}dinger equation. Whereas the nonrelativistic
model fails severely, both ZR and FR relativistic DWIA models provide an
excellent description of the data. For the FR predictions, it is necessary to
invoke a 20% reduction of sigma-nucleon and omega-nucleon coupling constants as
well as for -, - and -meson masses, by the nuclear
medium. On the other hand, the ZR predictions suggest that the strong
interaction in the nuclear medium is adequately represented by the free
nucleon-nucleon interaction associated with the impulse approximation. We also
demonstrate that, although the analyzing power is relatively insensitive to the
use different relativistic global optical potential parameter sets, the
prominent oscillatory behavior of this observable is largely attributed to
distortion of the scattering wave functions relative to their plane wave
values.Comment: 16 pages, 3 figures, submitted to Phys. Rev.
Studies of the Giant Dipole Resonance in Al, Ca, Fe, Ni and Pb with high energy-resolution inelastic proton scattering under 0
A survey of the fine structure of the Isovector Giant Dipole Resonance
(IVGDR) was performed, using the recently commissioned zero-degree facility of
the K600 magnetic spectrometer at iThemba LABS. Inelastic proton scattering at
an incident energy of 200 MeV was measured on Al, Ca, Fe,
Ni and Pb. A high energy resolution (
40 keV FWHM) could be achieved after utilising faint-beam and
dispersion-matching techniques. Considerable fine structure is observed in the
energy region of the IVGDR and characteristic energy scales are extracted from
the experimental data by means of a wavelet analysis. The comparison with
Quasiparticle-Phonon Model (QPM) calculations provides insight into the
relevance of different giant resonance decay mechanisms. Photoabsorption cross
sections derived from the data assuming dominance of relativistic Coulomb
excitation are in fair agreement with previous work using real photons.Comment: 15 pages, 15 figure
Changes in neutrophil count, creatine kinases and muscle soreness after repeated bouts of downhill running
Objective. A primary objective was to examine circulating neutrophil count after repeated bouts of downhill running. An additional aim was to determine creatine kinase (CK)
levels during the initial 12 hours, after repeated DHRs.
Design. Eleven healthy, untrained Caucasian males performed 2 x 60 min bouts of DHR (-13.5%), spaced 14 days
apart, at a speed equal to 75% VO2max on a level grade. Blood was collected before, after, and every hour for 12 hours, and every 24 hours for 6 days. Absolute neutrophil
count, CK, and delayed-onset muscle soreness (DOMS) were assessed. Results were analysed using repeated measures ANOVA (
Wavelet signatures of -splitting of the Isoscalar Giant Quadrupole Resonance in deformed nuclei from high-resolution (p,p) scattering off Nd
The phenomenon of fine structure of the Isoscalar Giant Quadrupole Resonance
(ISGQR) has been studied with high energy-resolution proton inelastic
scattering at iThemba LABS in the chain of stable even-mass Nd isotopes
covering the transition from spherical to deformed ground states. A wavelet
analysis of the background-subtracted spectra in the deformed 146,148,150Nd
isotopes reveals characteristic scales in correspondence with scales obtained
from a Skyrme RPA calculation using the SVmas10 parameterization. A semblance
analysis shows that these scales arise from the energy shift between the main
fragments of the K = 0, 1 and K = 2 components.Comment: 7 pages, 6 figure
Low-energy electric dipole response in 120Sn
The electric dipole strength in 120Sn has been extracted from proton
inelastic scattering experiments at E_p = 295 MeV and at forward angles
including 0 degree. Below neutron threshoild it differs from the results of a
120Sn(gamma,gamma') experiment and peaks at an excitation energy of 8.3 MeV.
The total strength corresponds to 2.3(2)% of the energy-weighted sum rule and
is more than three times larger than what is observed with the (gamma,gamma')
reaction. This implies a strong fragmentation of the E1 strength and/or small
ground state branching ratios of the excited 1- states.Comment: 7 pages, 6 figure
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