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Knowledge, attitudes and practices towards blood donation in Barbados
YesBackground: The World Health Organization (WHO) recommends 100% blood should be from voluntary non-remunerated donors (VNRD) yet the majority of blood donations (75%) in Barbados are family/replacement donations. Increasing VNRD is paramount to achieving a safe, reliable blood supply and understanding the population is a strategy suggested by the WHO to inform donor recruitment and education.
Objective: To obtain information to devise strategies for a voluntary donor mobilization campaign in Barbados.
Methods: Participants in Barbados (n=429) completed a self-administered questionnaire in 2014. The questionnaire comprised 31 questions including demographics (age, sex, highest educational attainment) and blood donation-related knowledge, attitudes and practices. Analysis of variance, t-test and linear regression were used to analyse data.
Results: Fifty-three per cent (n=219) of participants had previously donated blood; only 23.9% of these had donated within the past two years and almost half were family/replacement donors only. Knowledge deficits included blood donation requirements, deferral factors and maximum yearly donations. Most participants (79%) were willing to donate with more information. Participants with higher educational attainment and previous donors had higher total knowledge and attitude scores (p<0.01). Single, female, and younger participants were less likely to donate blood (p<0.05).
Conclusion: Barbados can likely increase voluntary blood donation rates by addressing knowledge deficits through education campaigns and increasing awareness of the need for donation
Nonabelian D-branes and Noncommutative Geometry
We discuss the nonabelian world-volume action which governs the dynamics of N
coincident Dp-branes. In this theory, the branes' transverse displacements are
described by matrix-valued scalar fields, and so this is a natural physical
framework for the appearance of noncommutative geometry. One example is the
dielectric effect by which Dp-branes may be polarized into a noncommutative
geometry by external fields. Another example is the appearance of
noncommutative geometries in the description of intersecting D-branes of
differing dimensions, such as D-strings ending on a D3- or D5-brane. We also
describe the related physics of giant gravitons.Comment: 21 pages, Latex, ref. adde
Strings between branes
D-brane configurations containing fundamental strings are constructed as
classical solutions of Yang-Mills theory. The fundamental strings in these
systems stretch between D-branes. In the case of D1-branes, this construction
gives smooth (classical) resolutions of string junctions and string networks.
Using a non-abelian Yang-Mills analysis of the string current, the string
charge density is computed and is shown to have support in the region between
the D-brane world-volumes. The 't Hooft-Polyakov monopole is analyzed using
similar methods, and is shown to contain D-strings whose flux has support off
the D-brane world-volume defined by the Higgs scalar field, when this field is
interpreted in terms of a transverse dimension. The constructions presented
here are used to give a qualitative picture of tachyon condensation in the
Yang-Mills limit, where fundamental strings and lower-dimensional D-branes
arise in a volume of space-time where brane-antibrane annihilation has
occurred.Comment: 35 pages, 16 eps figures, JHEP style; v2: a comment adde
Discriminating among Earth composition models using geo-antineutrinos
It has been estimated that the entire Earth generates heat corresponding to
about 40 TW (equivalent to 10,000 nuclear power plants) which is considered to
originate mainly from the radioactive decay of elements like U, Th and K,
deposited in the crust and mantle of the Earth. Radioactivity of these elements
produce not only heat but also antineutrinos (called geo-antineutrinos) which
can be observed by terrestrial detectors. We investigate the possibility of
discriminating among Earth composition models predicting different total
radiogenic heat generation, by observing such geo-antineutrinos at Kamioka and
Gran Sasso, assuming KamLAND and Borexino (type) detectors, respectively, at
these places. By simulating the future geo-antineutrino data as well as reactor
antineutrino background contributions, we try to establish to which extent we
can discriminate among Earth composition models for given exposures (in units
of kt yr) at these two sites on our planet. We use also information on
neutrino mixing parameters coming from solar neutrino data as well as KamLAND
reactor antineutrino data, in order to estimate the number of geo-antineutrino
induced events.Comment: 24 pages, 10 figures, final version to appear in JHE
Comment on Counting Black Hole Microstates Using String Dualities
We discuss a previous attempt at a microscopic counting of the entropy of
asymptotically flat non-extremal black-holes. This method used string dualities
to relate 4 and 5 dimensional black holes to the BTZ black hole. We show how
the dualities can be justified in a certain limit, equivalent to a near horizon
limit, but the resulting spacetime is no longer asymptotically flat.Comment: 10 pages, harvmac. v(2) typo correcte
Closed String Field Theory with Dynamical D-brane
We consider a closed string field theory with an arbitrary matter current as
a source of the closed string field. We find that the source must satisfy a
constraint equation as a consequence of the BRST invariance of the theory. We
see that it corresponds to the covariant conservation law for the matter
current, and the equation of motion together with this constraint equation
determines the classical behavior of both the closed string field and the
matter. We then consider the boundary state (D-brane) as an example of a
source. We see that the ordinary boundary state cannot be a source of the
closed string field when the string coupling g turns on. By perturbative
expansion, we derive a recursion relation which represents the bulk
backreaction and the D-brane recoil. We also make a comment on the rolling
tachyon boundary state.Comment: 30 pages, LaTeX2e, no figures. Typos are correcte
Boundary Liouville theory at c=1
The c=1 Liouville theory has received some attention recently as the
Euclidean version of an exact rolling tachyon background. In an earlier paper
it was shown that the bulk theory can be identified with the interacting c=1
limit of unitary minimal models. Here we extend the analysis of the c=1-limit
to the boundary problem. Most importantly, we show that the FZZT branes of
Liouville theory give rise to a new 1-parameter family of boundary theories at
c=1. These models share many features with the boundary Sine-Gordon theory, in
particular they possess an open string spectrum with band-gaps of finite width.
We propose explicit formulas for the boundary 2-point function and for the
bulk-boundary operator product expansion in the c=1 boundary Liouville model.
As a by-product of our analysis we also provide a nice geometric interpretation
for ZZ branes and their relation with FZZT branes in the c=1 theory.Comment: 37 pages, 1 figure. Minor error corrected, slight change in result
(1.6
Mass Spectra of Supersymmetric Yang-Mills Theories in 1+1 Dimensions
Physical mass spectra of supersymmetric Yang-Mills theories in 1+1 dimensions
are evaluated in the light-cone gauge with a compact spatial dimension. The
supercharges are constructed and the infrared regularization is unambiguously
prescribed for supercharges, instead of the light-cone Hamiltonian. This
provides a manifestly supersymmetric infrared regularization for the
discretized light-cone approach. By an exact diagonalization of the supercharge
matrix between up to several hundred color singlet bound states, we find a
rapidly increasing density of states as mass increases.Comment: LaTeX file, 32 page, 7 eps figure
General structure of the photon self-energy in non-commutative QED
We study the behavior of the photon two point function, in non-commutative
QED, in a general covariant gauge and in arbitrary space-time dimensions. We
show, to all orders, that the photon self-energy is transverse. Using an
appropriate extension of the dimensional regularization method, we evaluate the
one-loop corrections, which show that the theory is renormalizable. We also
prove, to all orders, that the poles of the photon propagator are gauge
independent and briefly discuss some other related aspects.Comment: 16 pages, revtex4. This is the final version to be published in Phys.
Rev.
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