780 research outputs found
Abelian Higgs Hair for Rotating and Charged Black Holes
We study the problem of vortex solutions in the background of rotating black
holes in both asymptotically flat and asymptoticlly anti de Sitter spacetimes.
We demonstrate the Abelian Higgs field equations in the background of four
dimensional Kerr, Kerr-AdS and Reissner-Nordstrom-AdS black holes have vortex
line solutions. These solutions, which have axial symmetry, are generalization
of the Nielsen-Olesen string. By numerically solving the field equations in
each case, we find that these black holes can support an Abelian Higgs field as
hair. This situation holds even in the extremal case, and no flux-expulsion
occurs. We also compute the effect of the self gravity of the Abelian Higgs
field show that the the vortex induces a deficit angle in the corresponding
black hole metrics.Comment: 22 pages, 16 figures, a section about the vortex self gravity on Kerr
black hole added, extremal black holes considered, one figure changed, one
reference adde
Cost Comparison of Methyl Bromide and Sulfuryl Fluoride (ProFume®) for Fumigating Food Processing Facilities, Warehouses, and Cocoa Beans
Costs of fumigating a food processing/warehouse facility using methyl bromide and sulfuryl fluoride (ProFume®) were compared using an economic-engineering approach. The two fumigants were also compared for fumigating cocoa beans. Sulfuryl fluoride is economically feasible for cocoa beans. It is economically feasible for some, but not all, applications in food processing facilities and warehouses. Keywords: Economics, Cost, Benefit, Fumigation methyl bromide, Sulfuryl fluoride, ProFume
Asynchrony between the rates of standing height gain and bone mass accumulation during puberty
During puberty, the marked increases in both standing height and bone mass appear to be dissociated in time, the former occurring earlier than the latter. However, the age or pubertal stage at which this dissociation is maximal in girls as opposed to boys, and whether this dissociation is similar at all parts of the skeleton, are not clearly established. Standing height and bone mineral mass, as assessed by measuring areal bone mineral density (BMD), at the levels of the lumbar spine, femoral neck and midfemoral shaft, were measured in 98 females and 100 males between the ages of 9 and 19 years twice at a 1-year interval. In males, the greatest difference between height and BMD gains occurred in the 13-14 year age group and was more pronounced for the lumbar spine and femoral neck than for the midfemoral shaft. In females, the greatest difference was detectable at a younger age (11-12 year age group) and appeared to be of a lower magnitude than in males. In both genders, the maximal difference occurred during the period of peak height velocity, which corresponded to the pubertal stages P2-P3. Such a dissociation between the rates of statural growth and mineral mass accrual could define a state of relatively low bone mass and contribute to the higher incidence of fracture known to occur at the age and/or pubertal stage when this dissociation is maxima
Thick domain wall universes
We investigate the spacetime of a thick gravitating domain wall for a general
potential . Using general analytical arguments we show that all
nontrivial solutions fall into two categories: those interpretable as an
isolated domain wall with a cosmological event horizon, and those which are
pure false vacuum de Sitter solutions. Although this latter solution is always
unstable to the field rolling coherently to its true vacuum, we show that there
is an additional instability to wall formation if the scalar field does not
couple too strongly to gravity. Using the and sine-Gordon
models as illustrative examples, we investigate the phase space of the
gravitating domain wall in detail numerically, following the solutions from
weak to strong gravity. We find excellent agreement with the analytic work.
Then, we analyse the domain wall in the presence of a cosmological constant
finding again the two kinds of solutions, wall and de Sitter, even in the
presence of a negative cosmological constant.Comment: 20 pages revtex, epsfig, references added, some conclusions altere
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