290 research outputs found
Minimising gear conflict and resource sharing issues in the Shark Bay trawl fisheries and promotion of scallop recruitment
Objectives 1. To determine size specific recapture mortality rates of Amusium balloti as a result of repeated capture and release experiments and gear impacts on newly recruited (juvenile) scallops. 2. To determine the impacts of various scallop mesh sizes for the capture of the target size of Amusium balloti and its impact on damage to and retention of prawns. 3. To investigate if small-scale spatial closures assist recruitment of Amusium balloti by reducing gear impacts and capture mortality but without affecting overall prawn catches. 4. To examine whether existing hydrodynamic models can guide the selection of spatial closures and to investigate the larval transport mechanisms of both prawn and scallop larvae in Shark Bay
The goitre rate, its association with reproductive failure, and the knowledge of iodine deficiency disorders (IDD) among women in Ethiopia: Cross-section community based study
<p>Abstract</p> <p>Background</p> <p>Iodine deficiency is severe public health problem in Ethiopia. Although urinary iodine excretion level (UIE) is a better indicator for IDD the goitre rate is commonly used to mark the public health significance. The range of ill effect of IDD is however beyond goitre in Ethiopia. In this study the prevalence of goitre and its association with reproductive failure, and the knowledge of women on Iodine Deficiency were investigated.</p> <p>Methods</p> <p>A cross-section community based study was conducted during February to May 2005 in 10998 women in child bearing age of 15 to 49 years. To assess the state of iodine deficiency in Ethiopia, a multistage "Proportional to Population Size" (PPS) sampling methods was used, and WHO/UNICEF/ICCIDD recommended method for goitre classification.</p> <p>Results</p> <p>Total goitre prevalence (weighted) was 35.8% (95% CI 34.5–37.1), 24.3% palpable and 11.5% visible goitre. This demonstrates that more than 6 million women were affected by goitre.</p> <p>Goitre prevalence in four regional states namely Southern Nation Nationalities and People (SNNP), Oromia, Bebshandul-Gumuz and Tigray was greater than 30%, an indication of severe iodine deficiency. In the rest of the regions except Gambella, the IDD situation was mild to moderate. According to WHO/UNICEF/ICCIDD this is a lucid indication that IDD is a major public health problem in Ethiopia. Women with goitre experience more pregnancy failure (X<sup>2 </sup>= 16.5, p < 0.001; OR = 1.26, 1.12 < OR < 1.41) than non goitrous women. Similarly reproductive failure in high goitre endemic areas was significantly higher (X<sup>2 </sup>= 67.52; p < 0.001) than in low. More than 90% of child bearing age women didn't know the cause of iodine deficiency and the importance of iodated salt.</p> <p>Conclusion</p> <p>Ethiopia is at risk of iodine deficiency disorders. The findings presented in this report emphasis on a sustainable iodine intervention program targeted at population particularly reproductive age women. Nutrition education along with Universal Salt Iodization program and iodized oil capsule distribution in some peripheries where iodine deficiency is severe is urgently required.</p
Non-spherical shapes of capsules within a fourth-order curvature model
We minimize a discrete version of the fourth-order curvature based Landau
free energy by extending Brakke's Surface Evolver. This model predicts
spherical as well as non-spherical shapes with dimples, bumps and ridges to be
the energy minimizers. Our results suggest that the buckling and faceting
transitions, usually associated with crystalline matter, can also be an
intrinsic property of non-crystalline membranes.Comment: 6 pages, 4 figures (LaTeX macros EPJ), accepted for publication in
EPJ
First-Order Melting and Dynamics of Flux Lines in a Model for YBaCuO
We have studied the statics and dynamics of flux lines in a model for YBCO,
using both Monte Carlo simulations and Langevin dynamics. For a clean system,
both approaches yield the same melting curve, which is found to be weakly first
order with a heat of fusion of about per vortex pancake at a
field of The time averaged magnetic field distribution
experienced by a fixed spin is found to undergo a qualitative change at
freezing, in agreement with NMR and experiments. Melting in the
clean system is accompanied by a proliferation of free disclinations which show
a clear B-dependent 3D-2D crossover from long disclination lines parallel to
the c-axis at low fields, to 2D ``pancake'' disclinations at higher fields.
Strong point pins produce a logarithmical relaxation which results from
slow annealing out of disclinations in disordered samples.Comment: 31 pages, latex, revtex, 12 figures available upon request, No major
changes to the original text, but some errors in the axes scale for Figures 6
and 7 were corrected(new figures available upon request), to be published in
Physical Review B, July 199
Phase Transitions and Vortex Line Entanglement in a Model High Temperature Superconductor
Monte Carlo simulations of the uniformly frustrated 3d XY model are used to
model vortex line fluctuations in high temperature superconductors in an
applied magnetic field. We find two distinct phase transitions. At a lower
T_{c\perp}, the vortex lattice melts and coherence is lost in planes
perpendicular to the magnetic field. At a higher T_{cz}, a vortex tangle
percolates throughout the system, and coherence is lost parallel to the
magnetic field. Cooling below T_{cz}, high energy barriers for vortex line
cutting lead to an entangled glassy state. Figures available upon request to
[email protected]: 20 pages, 15 figures, RevTex3.0, UR-93-ST0
Flux Pinning and Phase Transitions in Model High-Temperature Superconductors with Columnar Defects
We calculate the degree of flux pinning by defects in model high-temperature
superconductors (HTSC's). The HTSC is modeled as a three-dimensional network of
resistively-shunted Josephson junctions in an external magnetic field,
corresponding to a HTSC in the extreme Type-II limit. Disorder is introduced
either by randomizing the coupling between grains (Model A disorder) or by
removing grains (Model B disorder). Three types of defects are considered:
point disorder, random line disorder, and periodic line disorder; but the
emphasis is on random line disorder. Static and dynamic properties of the
models are determined by Monte Carlo simulations and by solution of the
analogous coupled overdamped Josephson equations in the presence of thermal
noise. Random line defects considerably raise the superconducting transition
temperature T, and increase the apparent critical current density
J, in comparison to the defect-free crystal. They are more effective
in these respects than a comparable volume density of point defects, in
agreement with the experiments of Civale {\it et al}. Periodic line defects
commensurate with the flux lattice are found to raise T even more than
do random line defects. Random line defects are most effective when their
density approximately equals the flux density. Near T, our static and
dynamic results appear consistent with the anisotropic Bose glass scaling
hypotheses of Nelson and Vinokur, but with possibly different critical indices:Comment: 10 pages, LaTeX(REVTeX v3.0, twocolumn), 11 figures (not included
Flux lattice melting and depinning in the weakly frustrated 2D XY model
Monte Carlo simulations of the frustrated 2D XY model were carried out at
small commensurate values of the frustration . For a single
transition was observed at which phase coherence (finite helicity modulus) and
vortex lattice orientational order vanish together. For a new phase in
which phase coherence is absent but orientational order persists was observed.
Where comparison is possible, the results are in detailed agreement with the
behavior of the lattice Coulomb gas model of vortices. It is argued that the
helicity modulus of the frustrated 2D XY model vanishes for any finite
temperature in the limit of weak frustration .Comment: 4 pages, RevTeX, 3 figures in separate uuencoded file The manuscript
will appear in Phys. Rev.
First-Order Melting of a Moving Vortex Lattice: Effects of Disorder
We study the melting of a moving vortex lattice through numerical simulations
with the current driven 3D XY model with disorder. We find that there is a
first-order phase transition even for large disorder when the corresponding
equilibrium transition is continuous. The low temperature phase is an
anisotropic moving glass.Comment: Important changes from original version. Finite size analysis of
results has been added. Figure 2 has been changed. There is a new additional
Figure. To be published in Physical Review Letter
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