6,040 research outputs found
Late cutaneous schistosomiasis representing an isolated skin manifestation of Schistosoma mansoni infection
Ectopic late cutaneous schistosomiasis is usually preceded or accompanied by visceral schistosomiasis infection. Our patient presented the very rare case of late cutaneous schistosomiasis as an isolated skin manifestation. Perigenital lesions occurred 1 year after contact with infested water. Identification of the few eggs remaining in the late lesion among the dense cellular infiltrate was difficult. Electron-microscopic studies clearly demonstrated the characteristic eggshell ultrastructure. Copyright (C) 2000 S. Karger AG, Basel
Explicit Global Coordinates for Schwarzschild and Reissner-Nordstroem
We construct coordinate systems that cover all of the Reissner-Nordstroem
solution with m>|q| and m=|q|, respectively. This is possible by means of
elementary analytical functions. The limit of vanishing charge q provides an
alternative to Kruskal which, to our mind, is more explicit and simpler. The
main tool for finding these global charts is the description of highly
symmetrical metrics by two-dimensional actions. Careful gauge fixing yields
global representatives of the two-dimensional theory that can be rewritten
easily as the corresponding four-dimensional line elements.Comment: 12 pages, 3 Postscript figures, sign error in Eq. (37) and below
corrected, references and Note added; to appear in Class. Quantum Gra
O stars effective temperature and HII regions ionization parameter gradients in the Galaxy
Extensive photoionization model grids are computed for single star HII
regions using stellar atmosphere models from the WM-basic code. Mid-IR emission
line intensities are predicted and diagnostic diagrams of [NeIII]/[NeII] and
[SIV]/[SIII] excitation ratio are build, taking into account the metallicities
of both the star and the HII region. The diagrams are used in conjunction with
galactic HII region observations obtained with the ISO Observatory to determine
the effective temperature Teff of the exciting O stars and the mean ionization
parameter U. Teff and U are found to increase and decrease, respectively, with
the metallicity of the HII region represented by the [Ne/Ne_sol] ratio. No
evidence is found for gradients of Teff or U with galactocentric distance Rgal.
The observed excitation sequence with Rgal is mainly due to the effect of the
metallicity gradient on the spectral ionizing shape, upon which the effect of
an increase in Teff with Z is superimposed. We show that not taking properly
into account the effect of metallicity on the ionizing shape of the stellar
atmosphere would lead to an apparent decrease of Teff with Z and an increase of
Teff with Rgal.Comment: Accepted in Ap
Decoherence in a dynamical quantum phase transition
Motivated by the similarity between adiabatic quantum algorithms and quantum
phase transitions, we study the impact of decoherence on the sweep through a
second-order quantum phase transition for the prototypical example of the Ising
chain in a transverse field and compare it to the adiabatic version of Grovers
search algorithm, which displays a first order quantum phase transition. For
site-independent and site-dependent coupling strengths as well as different
operator couplings, the results show that (in contrast to first-order
transitions) the impact of decoherence caused by a weak coupling to a rather
general environment increases with system size (i.e., number of spins/qubits).
This might limit the scalability of the corresponding adiabatic quantum
algorithm.Comment: 14 pages, 9 figure
The High Chromospheres of the Late A Stars
We report the detection of N V 1239 A transition region emission in HST/GHRS
spectra of the A7 V stars, Alpha Aql and Alpha Cep. Our observations provide
the first direct evidence of 1-3 x 10^5 K material in the atmospheres of normal
A-type stars. For both stars, and for the mid-A--type star Tau3 Eri, we also
report the detection of chromospheric emission in the Si III 1206 A line. At a
B-V color of 0.16 and an effective temperature of 8200 K, Tau3 Eri becomes the
hottest main sequence star known to have a chromosphere and thus an outer
convection zone. We see no firm evidence that the Si III line surface fluxes of
the A stars are any lower than those of moderately active, solar-type, G and K
stars. This contrasts sharply with their coronal X-ray emission, which is >100
times weaker than that of the later-type stars. Given the strength of the N V
emission observed here, it now appears unlikely that the X-ray faintness of the
A stars is due to their forming very cool, <= 1 MK coronae. An alternative
explanation in terms of mass loss in coronal winds remains a possibility,
though we conclude from moderate resolution spectra of the Si III lines that
such winds, if they exist, do not penetrate into the chromospheric Si
III--forming layers of the star, since the profiles of these lines are *not*
blueshifted, and may well be redshifted with respect to the star.Comment: LaTex, 12 pages, 3 Postscript figures, uses aaspp4, accepted by Ap
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