21,518 research outputs found
Implementing veterinary and animal welfare regulations in semi-natural pastoral landscapes in The Netherlands.
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
Spin entanglement, decoherence and Bohm's EPR paradox
We obtain criteria for entanglement and the EPR paradox
for spin-entangled particles and analyse the effects of decoherence caused
by absorption and state purity errors. For a two qubit photonic state,
entanglement can occur for all transmission efficiencies. In this case,
the state preparation purity must be above a threshold value. However,
Bohmâs spin EPR paradox can be achieved only above a critical level of
loss. We calculate a required efficiency of 58%, which appears achievable
with current quantum optical technologies. For a macroscopic number of
particles prepared in a correlated state, spin entanglement and the EPR
paradox can be demonstrated using our criteria for efficiencies η > 1/3
and η > 2/3 respectively. This indicates a surprising insensitivity to loss
decoherence, in a macroscopic system of ultra-cold atoms or photons
Studies on processing, particle formation, and immunogenicity of the HIV-1 gag gene product: a possible component of a HIV vaccine
Antigens in a particulate conformation were shown to be highly immunogenic in mammals. For this reason, the particle forming capacity of derivatives of the HIV-1 group specific core antigen p55 gag was assayed and compared dependent on various expression systems: recombinant bacteria, vaccinia- and baculoviruses were established encoding the entire core protein p55 either in its authentic sequence or lacking the myristylation consensus signal. Moreover, p55 gag was expressed in combination with the protease (p55-PR) or with the entire polymerase (p55-pol), respectively. Budding of 100-160 nm p55 core particles, resembling immature HIV-virions, was observed in the eucaryotic expression systems only. In comparison to the vaccinia virus driven expression of p55 in mammalian cells, considerably higher yields of particulate core antigen were obtained by infection of Spodoptera frugiperda (Sf9) insect cells with the recombinant Autographa californica nuclear polyhedrosis (AcMNPV) baculovirus. Mutation of the NH2-terminal myristylation signal sequence prevented budding of the immature core particles. Expression of the HIV p55-PR gene construct by recombinant baculovirus resulted in complete processing of the p55 gag precursor molecule in this system. The introduction of an artificial frameshift near the natural frameshift site resulted in constitutive expression of the viral protease and complete processing of p55, both in Escherichia coli and in vaccinia virus infected cells. Interestingly, significant processing of p55 resembling that of HIV infected H9 cells could also be achieved in the vaccinia system by fusing the entire pol gene to the gag gene. Moreover, processing was not found to be dependent on amino-terminal myristylation of the gag procursor molecule, which is in contrast to observations with type C and type D retrovirus. However, complete processing of p55 into p24, p17, p9 and p6 abolished particle formation. Purified immature HIV-virus like particles were highly immunogenic in rabbits, leading to a strong humoral immune response after immunization. Empty immature p55 gag particles represent a noninfectious and attractive candidate for a basic vaccine component
Comment on 'Stability of the semiclassical Einstein equation'
Some mathematical errors of the paper commented upon [W.-M. Suen, Phys. Rev.
D 40, (1989) 315] are corrected.Comment: 3 pages, LaTeX, reprinted from Phys. Rev. D 50 (1994) 545
Spin generation away from boundaries by nonlinear transport
In several situations of interest, spin polarization may be generated far
from the boundaries of a sample by nonlinear effects of an electric current,
even when such a generation is forbidden by symmetry in the linear regime. We
present an analytically solvable model where spin accumulation results from a
combination of current gradients, nonlinearity, and cubic anisotropy. Further,
we show that even with isotropic conductivity, nonlinear effects in a low
symmetry geometry can generate spin polarization far away from boundaries.
Finally, we find that drift from the boundaries results in spin polarization
patterns that dominate in recent experiments on GaAs by Sih et al. [Phys. Rev.
Lett. 97, 096605 (2006)]
Eigenfunctions for smooth expanding circle maps
We construct a real-analytic circle map for which the corresponding
Perron-Frobenius operator has a real-analytic eigenfunction with an eigenvalue
outside the essential spectral radius when acting upon -functions.Comment: 10 pages, 2 figure
The photospheric solar oxygen project: II. Non-concordance of the oxygen abundance derived from two forbidden lines
In the Sun, the two forbidden [OI] lines at 630 and 636 nm were previously
found to provide discrepant oxygen abundances. aims: We investigate whether
this discrepancy is peculiar to the Sun or whether it is also observed in other
stars. method: We make use of high-resolution, high signal-to-noise ratio
spectra of four dwarf to turn-off stars, five giant stars, and one sub-giant
star observed with THEMIS, HARPS, and UVES to investigate the coherence of the
two lines. results: The two lines provide oxygen abundances that are
consistent, within observational errors, in all the giant stars examined by us.
On the other hand, for the two dwarf stars for which a measurement was
possible, for Procyon, and for the sub-giant star Capella, the 636 nm line
provides systematically higher oxygen abundances, as already seen for the Sun.
conclusions: The only two possible reasons for the discrepancy are a serious
error in the oscillator strength of the NiI line blending the 630 nm line or
the presence of an unknown blend in the 636 nm line, which makes the feature
stronger. The CN lines blending the 636 nm line cannot be responsible for the
discrepancy. The CaI autoionisation line, on the red wing of which the 636 nm
line is formed, is not well modelled by our synthetic spectra. However, a
better reproduction of this line would result in even higher abundances from
the 636 nm, thus increasing the discrepancy.Comment: A&A accepte
Distribution of G-concurrence of random pure states
Average entanglement of random pure states of an N x N composite system is
analyzed. We compute the average value of the determinant D of the reduced
state, which forms an entanglement monotone. Calculating higher moments of the
determinant we characterize the probability distribution P(D). Similar results
are obtained for the rescaled N-th root of the determinant, called
G-concurrence. We show that in the limit this quantity becomes
concentrated at a single point G=1/e. The position of the concentration point
changes if one consider an arbitrary N x K bipartite system, in the joint limit
, K/N fixed.Comment: RevTeX4, 11 pages, 4 Encapsuled PostScript figures - Introduced new
results, Section II and V have been significantly improved - To appear on PR
Measurement of ortho-Positronium Properties in Liquid Scintillators
Pulse shape discrimination in liquid scintillator detectors is a
well-established technique for the discrimination of heavy particles from light
particles. Nonetheless, it is not efficient in the separation of electrons and
positrons, as they give rise to indistinguishable scintillator responses. This
inefficiency can be overtaken through the exploitation of the formation of
ortho-Positronium (o-Ps), which alters the time profile of light pulses induced
by positrons.
We characterized the o-Ps properties in the most commonly used liquid
scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the
effects of scintillator doping on the o-Ps properties for dopants currently
used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and
Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties
are suitable for enhancing the electron-positron discrimination.Comment: 4 pages, 1 figure. Contribution to proceedings of the Low
Radioactivity Techniques 2013 Workshop at LNGS, Assergi (AQ), Italy, April
10-12 201
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