3,536 research outputs found
Preliminary optical design of PANIC, a wide-field infrared camera for CAHA
In this paper, we present the preliminary optical design of PANIC (PAnoramic
Near Infrared camera for Calar Alto), a wide-field infrared imager for the
Calar Alto 2.2 m telescope. The camera optical design is a folded single
optical train that images the sky onto the focal plane with a plate scale of
0.45 arcsec per 18 micron pixel. A mosaic of four Hawaii 2RG of 2k x 2k made by
Teledyne is used as detector and will give a field of view of 31.9 arcmin x
31.9 arcmin. This cryogenic instrument has been optimized for the Y, J, H and K
bands. Special care has been taken in the selection of the standard IR
materials used for the optics in order to maximize the instrument throughput
and to include the z band. The main challenges of this design are: to produce a
well defined internal pupil which allows reducing the thermal background by a
cryogenic pupil stop; the correction of off-axis aberrations due to the large
field available; the correction of chromatic aberration because of the wide
spectral coverage; and the capability of introduction of narrow band filters
(~1%) in the system minimizing the degradation in the filter passband without a
collimated stage in the camera. We show the optomechanical error budget and
compensation strategy that allows our as built design to met the performances
from an optical point of view. Finally, we demonstrate the flexibility of the
design showing the performances of PANIC at the CAHA 3.5m telescope.Comment: This paper has been presented in the SPIE of Astronomical Telescopes
and Instrumentation 2008 in Marseille (France
Inhibition of Nuclear Factor of Activated T-Cells (NFAT) Suppresses Accelerated Atherosclerosis in Diabetic Mice
OBJECTIVE OF THE STUDY: Diabetic patients have a much more widespread and aggressive form of atherosclerosis and therefore, higher risk for myocardial infarction, peripheral vascular disease and stroke, but the molecular mechanisms leading to accelerated damage are still unclear. Recently, we showed that hyperglycemia activates the transcription factor NFAT in the arterial wall, inducing the expression of the pro-atherosclerotic protein osteopontin. Here we investigate whether NFAT activation may be a link between diabetes and atherogenesis. METHODOLOGY AND PRINCIPAL FINDINGS: Streptozotocin (STZ)-induced diabetes in apolipoprotein E(-/-) mice resulted in 2.2 fold increased aortic atherosclerosis and enhanced pro-inflammatory burden, as evidenced by elevated blood monocytes, endothelial activation- and inflammatory markers in aorta, and pro-inflammatory cytokines in plasma. In vivo treatment with the NFAT blocker A-285222 for 4 weeks completely inhibited the diabetes-induced aggravation of atherosclerosis, having no effect in non-diabetic mice. STZ-treated mice exhibited hyperglycemia and higher plasma cholesterol and triglycerides, but these were unaffected by A-285222. NFAT-dependent transcriptional activity was examined in aorta, spleen, thymus, brain, heart, liver and kidney, but only augmented in the aorta of diabetic mice. A-285222 completely blocked this diabetes-driven NFAT activation, but had no impact on the other organs or on splenocyte proliferation or cytokine secretion, ruling out systemic immunosuppression as the mechanism behind reduced atherosclerosis. Instead, NFAT inhibition effectively reduced IL-6, osteopontin, monocyte chemotactic protein 1, intercellular adhesion molecule 1, CD68 and tissue factor expression in the arterial wall and lowered plasma IL-6 in diabetic mice. CONCLUSIONS: Targeting NFAT signaling may be a novel and attractive approach for the treatment of diabetic macrovascular complications
Volume modulus inflation and a low scale of SUSY breaking
The relation between the Hubble constant and the scale of supersymmetry
breaking is investigated in models of inflation dominated by a string modulus.
Usually in this kind of models the gravitino mass is of the same order of
magnitude as the Hubble constant which is not desirable from the
phenomenological point of view. It is shown that slow-roll saddle point
inflation may be compatible with a low scale of supersymmetry breaking only if
some corrections to the lowest order Kahler potential are taken into account.
However, choosing an appropriate Kahler potential is not enough. There are also
conditions for the superpotential, and e.g. the popular racetrack
superpotential turns out to be not suitable. A model is proposed in which
slow-roll inflation and a light gravitino are compatible. It is based on a
superpotential with a triple gaugino condensation and the Kahler potential with
the leading string corrections. The problem of fine tuning and experimental
constraints are discussed for that model.Comment: 28 pages, 8 figures, comments and references added, minor change in
notation, version to be publishe
Ghrelin induces clock gene expression in the liver of goldfish in vitro via protein kinase C and protein kinase A pathways
International audienceThe liver is the most important link between the circadian system and metabolism. As a food-entrainable oscillator, the hepatic clock needs to be entrained by food-related signals. The objective of the present study was to investigate the possible role of ghrelin (an orexigenic peptide mainly synthesized in the gastrointestinal tract) as an endogenous synchronizer of the liver oscillator in teleosts. To achieve this aim, we first examined the presence of ghrelin receptors in the liver of goldfish. Then, the ghrelin regulation of clock gene expression in the goldfish liver was studied. Finally, the possible involvement of the phospholipase C/ protein kinase C (PLC/ PKC) and adenylate cyclase/protein kinase A (AC/PKA) intracellular signalling pathways was investigated. Ghrelin receptor transcripts, ghs-r1a, are present in the majority of goldfish hepatic cells. Ghrelin induced the mRNA expression of the positive (gbmal1a, gclock1a) and negative (gper genes) elements of the main loop of the molecular clock machinery, as well as grev-erba (auxiliary loop) in cultured liver. These effects were blocked, at least in part, by a ghrelin antagonist. Incubation of liver with a PLC inhibitor (U73122), a PKC activator (phorbol 12-myristate 13-acetate) and a PKC inhibitor (chelerythrine chloride) demonstrated that the PLC/ PKC pathway mediates such ghrelin actions. Experiments with an AC activator (forskolin) and a PKA inhibitor (H89) showed that grev-erba regulation could be due to activation of PKA. Taken together, the present results show for the first time in vertebrates a direct action of ghrelin on hepatic clock genes and support a role for this hormone as a temporal messenger in the entrainment of liver circadian functions
Modeling low-intensity ultrasound mechanotherapy impact on growing cancer stem cells
Targeted therapeutic interventions utilizing low-inten\-sity ultrasound
(LIUS) exhibit substantial potential for hindering the proliferation of cancer
stem cells. This investigation introduces a multiscale model and computational
framework to comprehensively explore the therapeutic LIUS on poroelastic tumor
dynamics, thereby unraveling the intricacies of mechanotransduction mechanisms
at play. Our model includes both macroscopic timescales encompassing days and
rapid timescales spanning from microseconds to seconds, facilitating an
in-depth comprehension of tumor behavior. We unveil the discerning suppression
or reorientation of cancer cell proliferation and migration, enhancing a
notable redistribution of cellular phases and stresses within the tumor
microenvironment. Our findings defy existing paradigms by elucidating the
impact of LIUS on cancer stem cell behavior. This endeavor advances our
fundamental understanding of mechanotransduction phenomena in the context of
LIUS therapy, thus underscoring its promising as a targeted therapeutic
modality for cancer treatment. Furthermore, our results make a substantial
contribution to the broader scientific community by shedding light on the
intricate interplay between mechanical forces, cellular responses, and the
spatiotemporal evolution of tumors. These insights hold the promising to
promote a new perspective for the future development of pioneering and highly
efficacious therapeutic strategies for combating cancer in a personalized
manner
Engineered transposon for improved cell line development
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Models of Modular Inflation and Their Phenomenological Consequences
We study models of modular inflation of the form expected to arise from low
energy effective actions of superstring theories. We argue on general grounds
that the most likely models of modular slow-roll inflation are small field
models in which the inflaton moves about a Planck distance from an extremum of
the potential. We then focus on models in which the inflaton is the bosonic
component of a single (complex) chiral superfield and explain the generic
difficulties in designing small field models of modular inflation. We then show
that if the Kaehler potential (KP) of the inflaton is logarithmic as in
perturbative string theories, then it is not possible to satisfy the slow-roll
conditions for any superpotential. We find that if the corrections to the KP
are large enough so it can be approximated by a canonical KP in the vicinity of
the extremum, then viable slow-roll inflation is possible. In this case,
several parameters have to be tuned to a fraction of a percent. We give a
prescription for designing successful small field supergravity models of
inflation when the KP is canonical and calculate the slow-roll parameters from
the superpotential parameters. Our results strengthen the case for models in
which the moduli slowly roll about a Planck distance from a relatively high
scale extremum that is located in the vicinity of the central region of moduli
space units. Generic models of this class predict a red spectrum of scalar
perturbations and negligible spectral index running. They also predict a
characteristic suppression of tensor perturbations despite the high scale of
inflation. Consequently, a detection of primordial tensor anisotropies or
spectral index running in cosmic microwave background observations in the
foreseeable future will rule out this entire class of modular inflation models.Comment: 35 pages, 1 figur
Inflation with racetrack superpotential and matter field
Several models of inflation with the racetrack superpotential for the volume
modulus coupled to a matter field are investigated. In particular, it is shown
that two classes of racetrack inflation models, saddle point and inflection
point ones, can be constructed in a fully supersymmetric framework with the
matter field F-term as a source of supersymmetry breaking and uplifting. Two
models of F-term supersymmetry breaking are considered: the Polonyi model and
the quantum corrected O'Raifeartaigh model. In the former case, both classes of
racetrack inflation models differ significantly from the corresponding models
with non-supersymmetric uplifting. The main difference is a quite strong
dominance of the inflaton by the matter field. In addition, fine-tuning of the
parameters is relaxed as compared to the original racetrack models. In the case
of the racetrack inflation models coupled to the O'Raifeartaigh model, the
matter field is approximately decoupled from the inflationary dynamics. In all
of the above models the gravitino mass is larger than the Hubble scale during
inflation. The possibility of having the gravitino much lighter than the Hubble
scale is also investigated. It is very hard to construct models with light
gravitino in which the volume modulus dominates inflation. On the other hand,
models in which the inflationary dynamics is dominated by the matter field are
relatively simple and seem to be more natural.Comment: 40 pages, 13 figures, references added, typos corrected, version to
be publishe
Dynamical Processing of Geophysical Signatures based on SPOT-5 Remote Sensing Imagery
An intelligent post-processing computational paradigm based on the use of dynamical filtering techniques modified to enhance the quality of reconstruction of geophysical signatures based on Spot-5 imagery is proposed. As a matter of particular study, a robust algorithm is reported for the analysis of the dynamic behavior of geophysical indexes extracted from the real-world remotely sensed scenes. The simulation results verify the efficiency of the approach as required for decision support in resources management
Liver transplantation in cirrhotic patients with diabetes mellitus: Midterm results, survival, and adverse events
Liver cirrhosis is frequently associated with diabetes mellitus (DM), and this
metabolic complication is also frequent after orthotopic liver transplantation
(OLT). The aim of our study is to investigate which factors are associated with
DM before and after OLT and their impact on post-OLT evolution. We evaluated the
prevalence of DM among 115 liver transplant candidates with cirrhosis and
assessed their evolution after OLT (median follow-up, 41 months). Sixteen
candidates had DM requiring pharmacological therapy (group A), 45 candidates had
DM controlled with diet (group B), and 54 candidates did not have DM (group C).
One-year and 3-year actuarial survival rates were 100% and 100% for group A, 91%
and 85% for group B, and 77% and 74% for group C, respectively (P <.03). Post-OLT
DM was more frequent in group A. The incidence of other metabolic complications,
major infections, rejection, and arterial hypertension; the need for
hospitalization; and renal and graft function of patients in groups A, B, and C
were similar. The only risk factor for DM 1 year after OLT on multivariate
analysis was pre-OLT DM requiring pharmacological treatment. The incidence of
complications, need for hospitalization, and renal and graft function 1 year
after OLT for patients with post-OLT DM were similar to those of patients without
post-OLT DM. In conclusion, patients with cirrhosis who have DM have a greater
risk for post-OLT DM, but their midterm survival is not worse than the survival
of those without DM
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