39 research outputs found
Some Aspects of Spherical Symmetric Extremal Dyonic Black Holes in 4d N=1 Supergravity
In this paper we study several aspects of extremal spherical symmetric black
hole solutions of four dimensional N=1 supergravity coupled to vector and
chiral multiplets with the scalar potential turned on. In the asymptotic region
the complex scalars are fixed and regular which can be viewed as the critical
points of the black hole and the scalar potentials with vanishing scalar
charges. It follows that the asymptotic geometries are of a constant and
non-zero scalar curvature which are generally not Einstein. These spaces could
also correspond to the near horizon geometries which are the product spaces of
a two anti-de Sitter surface and the two sphere if the value of the scalars in
both regions coincides. In addition, we prove the local existence of
non-trivial radius dependent complex scalar fields which interpolate between
the horizon and the asymptotic region. We finally give some simple
{\lC}^{n}-models with both linear superpotential and gauge couplings.Comment: 17 pages, no figure. Added an author. Major revision: typos and
grammar corrected, some statements modified, added a section about local
existence of scalar fields. Accepted for publication in Int J Mod Phys
Non-extremal Black Holes, Harmonic Functions, and Attractor Equations
We present a method which allows to deform extremal black hole solutions into
non-extremal solutions, for a large class of supersymmetric and
non-supersymmetric Einstein-Vector-Scalar type theories. The deformation is
shown to be largely independent of the details of the matter sector. While the
line element is dressed with an additional harmonic function, the attractor
equations for the scalars remain unmodified in suitable coordinates, and the
values of the scalar fields on the outer and inner horizon are obtained from
their fixed point values by making specific substitutions for the charges. For
a subclass of models, which includes the five-dimensional STU-model, we find
explicit solutions.Comment: 33 page
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Science objectives of the NOMAD spectrometer on ExoMars Trace Gas Orbiter
The "Nadir and Occultation for MArs Discovery" (NOMAD) instrument on ESA and NASA's ExoMars Trace Gas Orbiter (EMTGO) will conduct a spectroscopic survey of the Martian atmosphere in the infrared (IR) and UV/visible spectral regions, both in solar occultation and nadir looking modes (see: Vandaele, A.C., same session). In the IR wavelength domain, the spectral resolution (~0.15 cm-1) surpasses those of previous surveys of Mars by more than an order of magnitude, this channel's heritage derives from the SOIR instrument with proven success on ESA's Venus Express mission [1]. An additional light-weight channel UVIS extends the survey to UV and visible wavelengths with a 1-2 nm resolution. NOMAD will search for active geology, volcanism and life by looking for the atmospheric markers of these processes on Mars, confining the source regions, and providing crucial information on the nature of the processes involved. NOMAD will also extend the survey of major climatology cycles of Mars
Magnesium deficiency results in an increased formation of osteoclasts
Magnesium (Mg2+) deficiency is a frequently occurring disorder that leads to loss of bone mass, abnormal bone growth and skeletal weakness. It is not clear whether Mg2+ deficiency affects the formation and/or activity of osteoclasts. We evaluated the effect of Mg2+ restriction on these parameters. Bone marrow cells from long bone and jaw of mice were seeded on plastic and on bone in medium containing different concentrations of Mg2+ (0.8 mM which is 100% of the normal value, 0.4, 0.08 and 0 mM). The effect of Mg2+ deficiency was evaluated on osteoclast precursors for their viability after 3 days and proliferation rate after 3 and 6 days, as was mRNA expression of osteoclastogenesis-related genes and Mg2+-related genes. After 6 days of incubation, the number of tartrate resistant acid phosphatase-positive (TRACP+) multinucleated cells was determined, and the TRACP activity of the medium was measured. Osteoclastic activity was assessed at 8 days by resorption pit analysis. Mg2+ deficiency resulted in increased numbers of osteoclast-like cells, a phenomenon found for both types of marrow. Mg2+ deficiency had no effect on cell viability and proliferation. Increased osteoclastogenesis due to Mg2+ deficiency was reflected in higher expression of osteoclast-related genes. However, resorption per osteoclast and TRACP activity were lower in the absence of Mg2+. In conclusion, Mg2+ deficiency augmented osteoclastogenesis but appeared to inhibit the activity of these cells. Together, our in vitro data suggest that altered osteoclast numbers and activity may contribute to the skeletal phenotype as seen in Mg2+ deficient patients. © 2012 Elsevier Inc. All rights reserved
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Amniotic fluid cells express intestinal stem cell markers of Lgr 5 and Musashi-1
Artefactual serum hyperkalaemia and hypercalcaemia in essential thrombocythaemia
Aim—To investigate possible abnormalities of serum potassium and calcium levels in patients with essential thrombocythaemia and significant thrombocytosis. Methods—24 cases of essential thrombocythaemia with significant thrombocytosis (platelet count > 700 x 10(9)/litre) had serum potassium and calcium estimations performed at the time of maximum thrombocytosis before treatment, and at the time of low platelet count after treatment with cytoreductive drugs. Selected patients were further investigated with plasma sampling and estimation of ionised calcium and parathyroid hormone. Results—At the time of maximum thrombocytosis six patients had serum hyperkalaemia (> 5.5 mmol/litre) and five had serum hypercalcaemia (> 2.6 mmol/litre). Following treatment and reduction of the platelet count, hyperkalaemia resolved in all cases and hypercalcaemia in four of the five cases. Mean serum potassium and calcium concentrations were raised (p < 0.0001) at maximum thrombocytosis compared with the values when the platelet count was low. Serum potassium and calcium values were significantly correlated at all stages. Measurements on plasma consistently corrected the hyperkalaemia but not the hypercalcaemia. Serum hypercalcaemia was associated with raised ionised calcium and normal parathyroid hormone concentrations. Conclusions—Essential thrombocythaemia with significant thrombocytosis is associated with serum hyperkalaemia and hypercalcaemia. The probable mechanism of hypercalcaemia is the secretion of calcium in vitro from an excessive number of abnormally activated platelets. It is thus likely that the hypercalcaemia is an artefact, as is the hyperkalaemia. Key Words: thrombocythaemia • hypercalcaemia • hyperkalaemi