765 research outputs found
Matter radii of light halo nuclei
We re-examine the matter radii of diffuse halo nuclei, as deduced from
reaction cross section measurements at high energy. Careful consideration is
given to the intrinsic few-body structure of these projectiles and the
adiabatic nature of the projectile-target interaction. Using Li,
Be and B as examples we show that data require significantly
larger matter radii than previously reported. The revised value for Li
of 3.55 fm is consistent with three-body models with significant -intruder
state components, which reproduce experimental Li momentum distributions
following Li breakup, but were hitherto thought to be at variance with
cross section data.Comment: 8 pages RevTeX plus 5 Postscript figures. Figures also available at
http://www.ph.surrey.ac.uk/scnp/jakpub/figures.html Scheduled tentatively for
13May96 issue of Phys. Rev. Let
The Repression of Patriarchy and Imperialism in Barbara Kingslover’s The Poisonwood Bible
The present paper shows the special interesting case of Barbara Kingslover’s interweaving of the voicelessness of contemporary American women with the colonial subjugation and helplessness of an African nation in The Poisonwood Bible (1998). Through the critical lenses of Chinwa Achebe and Frantz Fanon this study focuses on showing Kingslover’s representation of and response to this double-layered marginalization and voicelessness of women and colonized nations. Drawing on Gayatri Spivak’s metaphor of speaking as a form of revolt against the overwhelming subjugation, this paper also shows how Kingslover creates voice to speak for the voiceless women and the colonized African nation, an attempt perhaps to undo the silencing carried out to sustain a patriarchal and imperialistic culture
Trichodysplasia Spinulosa
Trichodysplasia spinulosa (TS) is a unique, rare clinical and histological dermatologic entity described mainly in setting of immunosuppression. It is caused by a novel human polymoavirus, trichodysplasia spinulosa-associated polyomavirus (TSPyV). We report a biopsy-proven case of TS in a renal transplant patient presented to dermatology outpatient clinic in Montreal, Canada in 2015. Reduction of immunosuppression and/or anti-viral therapy is the main therapeutic strategies used to treat such cases. Our patient was managed with valgancyclovir with no obvious response. Subsequently, a trial of topical imiquimod was commenced. Awareness of TS can prompt early diagnosis and management to prevent possible complications.
Keywords: Trichodysplasia spinulosa, immunosuppression, organ-trasplant, human polyomavirus
Monte Carlo integration in Glauber model analysis of reactions of halo nuclei
Reaction and elastic differential cross sections are calculated for light
nuclei in the framework of the Glauber theory. The optical phase-shift function
is evaluated by Monte Carlo integration. This enables us to use the most
accurate wave functions and calculate the phase-shift functions without
approximation. Examples of proton nucleus (e.g. p-He, p-Li) and
nucleus-nucleus (e.g. HeC) scatterings illustrate the effectiveness
of the method. This approach gives us a possibility of a more stringent
analysis of the high-energy reactions of halo nuclei.Comment: 20 pages, 8 figure
Energy Dependence of Breakup Cross Sections of Halo Nucleus 8B and Effective Interactions
We study the energy dependence of the cross sections for nucleon removal of
8B projectiles. It is shown that the Glauber model calculations with
nucleon-nucleon t-matrix reproduce well the energy dependence of the breakup
cross sections of 8B. A DWBA model for the breakup cross section is also
proposed and results are compared with those of the Glauber model. We show that
to obtain an agreement between the DWBA calculations, the Glauber formalism,
and the experimental data, it is necessary to modify the energy behavior of the
effective interaction. In particular, the breakup potential has a quite
different energy dependence than the strong absorption potential.Comment: 13 pages, 4 figure
Extended sudden approximation model for high-energy nucleon removal reactions
A model based on the sudden approximation has been developed to describe high
energy single nucleon removal reactions. Within this approach, which takes as
its starting point the formalism of Hansen \cite{Anne2}, the nucleon-removal
cross section and the full 3-dimensional momentum distributions of the core
fragments including absorption, diffraction, Coulomb and nuclear-Coulomb
interference amplitudes, have been calculated. The Coulomb breakup has been
treated to all orders for the dipole interaction. The model has been compared
to experimental data for a range of light, neutron-rich psd-shell nuclei. Good
agreement was found for both the inclusive cross sections and momentum
distributions. In the case of C, comparison is also made with the
results of calculations using the transfer-to-the-continuum model. The
calculated 3-dimensional momentum distributions exhibit longitudinal and
transverse momentum components that are strongly coupled by the reaction for
s-wave states, whilst no such effect is apparent for d-waves. Incomplete
detection of transverse momenta arising fromlimited experimental acceptances
thus leads to a narrowing of the longitudinal distributions for nuclei with
significant s-wave valence neutron configurations, as confirmed by the data.
Asymmetries in the longitudinal momentum distributions attributed to
diffractive dissociation are also explored.Comment: 16 figures, submitted to Phys. Rev.
Probing halo nucleus structure through intermediate energy elastic scattering
This work addresses the question of precisely what features of few body
models of halo nuclei are probed by elastic scattering on protons at high
centre-of-mass energies. Our treatment is based on a multiple scattering
expansion of the proton-projectile transition amplitude in a form which is well
adapted to the weakly bound cluster picture of halo nuclei. In the specific
case of Li scattering from protons at 800 MeV/u we show that because
core recoil effects are significant, scattering crosssections can not, in
general, be deduced from knowledge of the total matter density alone.
We advocate that the optical potential concept for the scattering of halo
nuclei on protons should be avoided and that the multiple scattering series for
the full transition amplitude should be used instead.Comment: 8 pages REVTeX, 1 eps figure, accepted for publication in Phys. Rev.
Coulomb breakup effects on the optical potentials of weakly bound nuclei
The optical potential of halo and weakly bound nuclei has a long range part
due to the coupling to breakup that damps the elastic scattering angular
distributions. In order to describe correctly the breakup channel in the case
of scattering on a heavy target, core recoil effects have to be taken into
account. We show here that core recoil and nuclear breakup of the valence
nucleon can be consistently taken into account. A microscopic absorptive
potential is obtained within a semiclassical approach and its characteristics
can be understood in terms of the properties of the halo wave function and of
the reaction mechanism. Results for the case of medium to high energy reactions
are presented.Comment: 25 latex pages, 4 tables, 6 figures. Submitted to Nucl. Phys.
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