184 research outputs found
Alendronate or alfacalcidol in glucocorticoid-induced osteoporosis
BACKGROUND: Treatment with glucocorticoids is associated with bone loss starting soon after therapy is initiated and an increased risk of fracture. METHODS: We performed a randomized, double-placebo, double-blind clinical trial of 18 months' duration among patients with a rheumatic disease who were starting glucocorticoids at a daily dose that was equivalent to at least 7.5 mg of prednisone. A total of 201 patients were assigned to receive either alendronate (10 mg) and a placebo capsule of alfacalcidol daily or alfacalcidol (1 mu g) and a placebo tablet of alendronate daily. The primary outcome was the change in bone mineral density of the lumbar spine in 18 months; the secondary outcome was the incidence of morphometric vertebral deformities. RESULTS: A total of 100 patients received alendronate, and 101 received alfacalcidol; 163 patients completed the study. The bone mineral density of the lumbar spine increased by 2.1 percent in the alendronate group (95 percent confidence interval, 1.1 to 3.1 percent) and decreased by 1.9 percent in the alfacalcidol group (95 percent confidence interval, -3.1 to -0.7 percent). At 18 months, the mean difference of change in bone mineral density between the two groups was 4.0 percent (95 percent confidence interval, 2.4 to 5.5 percent). Three patients in the alendronate group had a new vertebral deformity, as compared with eight patients in the alfacalcidol group (of whom three had symptomatic vertebral fractures) (hazard ratio, 0.4; 95 percent confidence interval, 0.1 to 1.4). CONCLUSIONS: During this 18-month trial in patients with rheumatic diseases, alendronate was more effective in the prevention of glucocorticoid-induced bone loss than was alfacalcidol
Magnetic field generation through angular momentum exchange between circularly polarized radiation and charged particles
The interaction between circularly polarized (CP) radiation and charged particles can lead to generation of magnetic field through an inverse Faraday effect. The spin of the circularly polarized electromagnetic wave can be converted into the angular momentum of the charged particles so long as there is dissipation. We demonstrate this by considering two mechanisms of angular momentum absorption relevant for laser-plasma interactions: electron-ion collisions and ionization. The precise dissipative mechanism, however, plays a role in determining the efficiency of the magnetic field generation
Stochastic excitation of acoustic modes in stars
For more than ten years, solar-like oscillations have been detected and
frequencies measured for a growing number of stars with various characteristics
(e.g. different evolutionary stages, effective temperatures, gravities, metal
abundances ...).
Excitation of such oscillations is attributed to turbulent convection and
takes place in the uppermost part of the convective envelope. Since the
pioneering work of Goldreich & Keely (1977), more sophisticated theoretical
models of stochastic excitation were developed, which differ from each other
both by the way turbulent convection is modeled and by the assumed sources of
excitation. We review here these different models and their underlying
approximations and assumptions.
We emphasize how the computed mode excitation rates crucially depend on the
way turbulent convection is described but also on the stratification and the
metal abundance of the upper layers of the star. In turn we will show how the
seismic measurements collected so far allow us to infer properties of turbulent
convection in stars.Comment: Notes associated with a lecture given during the fall school
organized by the CNRS and held in St-Flour (France) 20-24 October 2008 ; 39
pages ; 11 figure
A Survey of Finite Algebraic Geometrical Structures Underlying Mutually Unbiased Quantum Measurements
The basic methods of constructing the sets of mutually unbiased bases in the
Hilbert space of an arbitrary finite dimension are discussed and an emerging
link between them is outlined. It is shown that these methods employ a wide
range of important mathematical concepts like, e.g., Fourier transforms, Galois
fields and rings, finite and related projective geometries, and entanglement,
to mention a few. Some applications of the theory to quantum information tasks
are also mentioned.Comment: 20 pages, 1 figure to appear in Foundations of Physics, Nov. 2006 two
more references adde
Quantum Attractor Flows
Motivated by the interpretation of the Ooguri-Strominger-Vafa conjecture as a
holographic correspondence in the mini-superspace approximation, we study the
radial quantization of stationary, spherically symmetric black holes in four
dimensions. A key ingredient is the classical equivalence between the radial
evolution equation and geodesic motion of a fiducial particle on the moduli
space M^*_3 of the three-dimensional theory after reduction along the time
direction. In the case of N=2 supergravity, M^*_3 is a para-quaternionic-Kahler
manifold; in this case, we show that BPS black holes correspond to a particular
class of geodesics which lift holomorphically to the twistor space Z of M^*_3,
and identify Z as the BPS phase space. We give a natural quantization of the
BPS phase space in terms of the sheaf cohomology of Z, and compute the exact
wave function of a BPS black hole with fixed electric and magnetic charges in
this framework. We comment on the relation to the topological string amplitude,
extensions to N>2 supergravity theories, and applications to automorphic black
hole partition functions.Comment: 43 pages, 6 figures; v2: typos and references added; v3: published
version, minor change
Prospects for asteroseismology
The observational basis for asteroseismology is being dramatically
strengthened, through more than two years of data from the CoRoT satellite, the
flood of data coming from the Kepler mission and, in the slightly longer term,
from dedicated ground-based facilities. Our ability to utilize these data
depends on further development of techniques for basic data analysis, as well
as on an improved understanding of the relation between the observed
frequencies and the underlying properties of the stars. Also, stellar modelling
must be further developed, to match the increasing diagnostic potential of the
data. Here we discuss some aspects of data interpretation and modelling,
focussing on the important case of stars with solar-like oscillations.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar
modelling', eds M. Marconi, D. Cardini & M. P. Di Mauro, Astrophys. Space
Sci., in the press Revision: correcting abscissa labels on Figs 1 and
Intrinsic resistance to PIM kinase inhibition in AML through p38α-mediated feedback activation of mTOR signaling
Although conventional therapies for acute myeloid leukemia (AML) and diffuse large B-cell lymphoma (DLBCL) are effective in inducing remission, many patients relapse upon treatment. Hence, there is an urgent need for novel therapies. PIM kinases are often overexpressed in AML and DLBCL and are therefore an attractive therapeutic target. However, in vitro experiments have demonstrated that intrinsic resistance to PIM inhibition is common. It is therefore likely that only a minority of patients will benefit from single agent PIM inhibitor treatment. In this study, we performed an shRNA-based genetic screen to identify kinases whose suppression is synergistic with PIM inhibition. Here, we report that suppression of p38α (MAPK14) is synthetic lethal with the PIM kinase inhibitor AZD1208. PIM inhibition elevates reactive oxygen species (ROS) levels, which subsequently activates p38α and downstream AKT/mTOR signaling. We found that p38α inhibitors sensitize hematological tumor cell lines to AZD1208 treatment in vitro and in vivo. These results were validated in ex vivo patient-derived AML cells. Our findings provide mechanistic and translational evidence supporting the rationale to test a combination of p38α and PIM inhibitors in clinical trials for AML and DLBCL
Tumour Angiogenesis in Uveal Melanoma Is Related to Genetic Evolution
Increased angiogenesis is associated with a higher metastasis- and mortality rate in uveal
melanoma (UM). Recently, it was demonstrated that genetic events, such as 8q-gain and BAP1-loss,
influence the level of immune infiltrate. We aimed to determine whether genetic events, and specific
cytokines, relate to angiogenesis in UM. Data from UM patients who underwent enucleation between
1999 and 2008 were analysed. Microvascular density (MVD) and the presence of infiltrating immune
cells were determined with immunohistochemistry (IHC) and immunofluorescence in 43 cases.
Chromosome status, BAP1 IHC and mRNA expression of angiogenesis-related genes were known
in 54 cases. Tumours with monosomy 3/BAP1-loss showed a higher MVD compared to tumours
with disomy 3/normal BAP1 expression (p = 0.008 and p = 0.004, respectively). Within BAP1-positive
lesions (n = 20), 8q-gain did not relate to MVD (p = 0.51). A high MVD was associated with an
increased expression of angiopoietin 2 (ANGPT2) (p = 0.041), Von Willebrand Factor (VWF) (p = 0.010),
a decreased expression of vascular endothelial growth factor B (VEGF-B) (p = 0.024), and increased
numbers of tumour-infiltrating macrophages (CD68+, p = 0.017; CD68+CD163+, p = 0.031) and
lymphocytes (CD4+, p = 0.027). Concluding, vascular density of UM relates to its genetic profile:
Monosomy 3 and BAP1-loss are associated with an increased MVD, while an early event (gain of 8q)
is not independently related to MVD, but may initiate a preparation phase towards development of
vessels. Interestingly, VEGF-B expression is decreased in UM with a high MVD
Positrons and antiprotons from inert doublet model dark matter
In the framework of the Inert Doublet Model, a very simple extension of the
Standard Model, we study the production and propagation of antimatter in cosmic
rays coming from annihilation of a scalar dark matter particle. We consider
three benchmark candidates, all consistent with the WMAP cosmic abundance and
existing direct detection experiments, and confront the predictions of the
model with the recent PAMELA, ATIC and HESS data. For a light candidate, M_{DM}
= 10 GeV, we argue that the positron and anti-proton fluxes may be large, but
still consistent with expected backgrounds, unless there is an enhancement
(boost factor) in the local density of dark matter. There is also a substantial
anti-deuteron flux which might be observable by future experiments. For a
candidate with M_{DM} = 70 GeV, the contribution to positron and anti-proton
fluxes is much smaller than the expected backgrounds. Even if a boost factor is
invoked to enhance the signals, the candidate is unable to explain the observed
positron and anti-proton excesses. Finally, for a heavy candidate, M_{DM} = 10
TeV, it is possible to fit the PAMELA excess (but, unfortunately, not the ATIC
one) provided there is a large enhancement, either in the local density of dark
matter or through the Sommerfeld effect.Comment: 17 pages ; v2: matches JCAP published versio
Evaluation of basil extract ( Ocimum basilicum L.) on oxidative, anti-genotoxic and anti-inflammatory effects in human leukocytes cell cultures exposed to challenging agents
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