1,326 research outputs found
Northern JHK Standard Stars for Array Detectors
We report J, H and K photometry of 86 stars in 40 fields in the northern
hemisphere. The fields are smaller than or comparable to a 4x4 arcmin
field-of-view, and are roughly uniformly distributed over the sky, making them
suitable for a homogeneous broadband calibration network for near-infrared
panoramic detectors. K magnitudes range from 8.5 to 14, and J-K colors from
-0.1 to 1.2. The photometry is derived from a total of 3899 reduced images;
each star has been measured, on average, 26.0 times per filter on 5.5 nights.
Typical errors on the photometry are about 0.012.Comment: 10 pages including 3 figures, one separate figure on four pages. The
finding chart of the AS-30 field and a few coordinates have been corrected.
GIF finding charts can also be found at
http://www.arcetri.astro.it/~hunt/std.htm
Signatures of supernova neutrino oscillations in the Earth mantle and core
The Earth matter effects on supernova (SN) neutrinos can be identified at a
single detector through peaks in the Fourier transform of their ``inverse
energy'' spectrum. The positions of these peaks are independent of the SN
models and therefore the peaks can be used as a robust signature of the Earth
matter effects, which in turn can distinguish between different neutrino mixing
scenarios. Whereas only one genuine peak is observable when the neutrinos
traverse only the Earth mantle, traversing also the core gives rise to multiple
peaks. We calculate the strengths and positions of these peaks analytically and
explore their features at a large scintillation detector as well as at a
megaton water Cherenkov detector through Monte Carlo simulations. We propose a
simple algorithm to identify the peaks in the actual data and quantify the
chances of a peak identification as a function of the location of the SN in the
sky.Comment: 17 pages, 9 figure
The TNG Near Infrared Camera Spectrometer
NICS (acronym for Near Infrared Camera Spectrometer) is the near-infrared
cooled camera-spectrometer that has been developed by the Arcetri Infrared
Group at the Arcetri Astrophysical Observatory, in collaboration with the
CAISMI-CNR for the TNG (the Italian National Telescope Galileo at La Palma,
Canary Islands, Spain).
As NICS is in its scientific commissioning phase, we report its observing
capabilities in the near-infrared bands at the TNG, along with the measured
performance and the limiting magnitudes. We also describe some technical
details of the project, such as cryogenics, mechanics, and the system which
executes data acquisition and control, along with the related software.Comment: 7 pages, 5 figures, compiled with A&A macros. A&A in pres
Geo-neutrinos: A systematic approach to uncertainties and correlations
Geo-neutrinos emitted by heat-producing elements (U, Th and K) represent a
unique probe of the Earth interior. The characterization of their fluxes is
subject, however, to rather large and highly correlated uncertainties. The
geochemical covariance of the U, Th and K abundances in various Earth
reservoirs induces positive correlations among the associated geo-neutrino
fluxes, and between these and the radiogenic heat. Mass-balance constraints in
the Bulk Silicate Earth (BSE) tend instead to anti-correlate the radiogenic
element abundances in complementary reservoirs. Experimental geo-neutrino
observables may be further (anti)correlated by instrumental effects. In this
context, we propose a systematic approach to covariance matrices, based on the
fact that all the relevant geo-neutrino observables and constraints can be
expressed as linear functions of the U, Th and K abundances in the Earth's
reservoirs (with relatively well-known coefficients). We briefly discuss here
the construction of a tentative "geo-neutrino source model" (GNSM) for the U,
Th, and K abundances in the main Earth reservoirs, based on selected
geophysical and geochemical data and models (when available), on plausible
hypotheses (when possible), and admittedly on arbitrary assumptions (when
unavoidable). We use then the GNSM to make predictions about several
experiments ("forward approach"), and to show how future data can constrain - a
posteriori - the error matrix of the model itself ("backward approach"). The
method may provide a useful statistical framework for evaluating the impact and
the global consistency of prospective geo-neutrino measurements and Earth
models.Comment: 17 pages, including 4 figures. To appear on "Earth, Moon, and
Planets," Special Issue on "Neutrino Geophysics," Proceedings of Neutrino
Science 2005 (Honolulu, Hawaii, Dec. 2005
Dedalo: looking for clusters explanations in a labyrinth of Linked Data
We present Dedalo, a framework which is able to exploit Linked Data to generate explanations for clusters. In general, any result of a Knowledge Discovery process, including clusters, is interpreted by human experts who use their background knowledge to explain them. However, for someone without such expert knowledge, those results may be difficult to understand. Obtaining a complete and satisfactory explanation becomes a laborious and time-consuming process, involving expertise in possibly different domains. Having said so, not only does the Web of Data contain vast amounts of such background knowledge, but it also natively connects those domains. While the efforts put in the interpretation process can be reduced with the support of Linked Data, how to automatically access the right piece of knowledge in such a big space remains an issue. Dedalo is a framework that dynamically traverses Linked Data to find commonalities that form explanations for items of a cluster. We have developed different strategies (or heuristics) to guide this traversal, reducing the time to get the best explanation. In our experiments, we compare those strategies and demonstrate that Dedalo finds relevant and sophisticated Linked Data explanations from different areas
Unusual Skin Toxicity after a Chemotherapic Combination
As known calciphylaxis (CPX) is a rare condition involving
subcutaneous vascular calcification and cutaneous necrosis, mostly
observed in patients with renal failure. However CPX may also
appear in patients affected by polymyositis, Sjogren syndrome, Lupus
Erythematosus systemicus, Sarcoidosis and rheumatoid arthritis,
especially in children. Clinically CPX can present itself as subcutaneous
nodules, infiltrate plaques or purpuric-like and livedo-like plaques,
while in the late stages necrotic ulcers (with a bizarre shape and severe
pain) may be the main cutaneous manifestations
Day-night asymmetry of high and low energy solar neutrino events in Super-Kamiokande and in the Sudbury Neutrino Observatory
In the context of solar neutrino oscillations among active states, we briefly
discuss the current likelihood of Mikheyev-Smirnov-Wolfenstein (MSW) solutions
to the solar neutrino problem, which appear to be currently favored at large
mixing, where small Earth regeneration effects might still be observable in
Super-Kamiokande (SK) and in the Sudbury Neutrino Observatory (SNO). We point
out that, since such effects are larger at high (low) solar neutrino energies
for high (low) values of the mass square difference \delta m^2, it may be
useful to split the night-day rate asymmetry in two separate energy ranges. We
show that the difference \Delta of the night-day asymmetry at high and low
energy may help to discriminate the two large-mixing solutions at low and high
\delta m^2 through a sign test, both in SK and in SNO, provided that the
sensitivity to \Delta can reach the (sub)percent level.Comment: 6 pages (RevTeX) + 4 figures (PostScript). Final version, to appear
in Phys. Rev.
Super-Kamiokande data and atmospheric neutrino decay
Neutrino decay has been proposed as a possible solution to the atmospheric
neutrino anomaly, in the light of the recent data from the Super-Kamiokande
experiment. We investigate this hypothesis by means of a quantitative analysis
of the zenith angle distributions of neutrino events in Super-Kamiokande,
including the latest (45 kTy) data. We find that the neutrino decay hypothesis
fails to reproduce the observed distributions of muons.Comment: 6 pages (RevTeX) + 2 figures (Postscript
Ribosomal stress activates eEF2K-eEF2 pathway causing translation elongation inhibition and recruitment of Terminal Oligopyrimidine (TOP) mRNAs on polysomes
The synthesis of adequate amounts of ribosomes is an essential task for the cell. It is therefore not surprising that regulatory circuits exist to organize the synthesis of ribosomal components. It has been shown that defect in ribosome biogenesis (ribosomal stress) induces apoptosis or cell cycle arrest through activation of the tumor suppressor p53. This mechanism is thought to be implicated in the pathophysiology of a group of genetic diseases such as Diamond Blackfan Anemia which are called ribosomopathies. We have identified an additional response to ribosomal stress that includes the activation of eukaryotic translation elongation factor 2 kinase with a consequent inhibition of translation elongation. This leads to a translational reprogramming in the cell that involves the structurally defined group of messengers called terminal oligopyrimidine (TOP) mRNAs which encode ribosomal proteins and translation factors. In fact, while general protein synthesis is decreased by the impairment of elongation, TOP mRNAs are recruited on polysomes causing a relative increase in the synthesis of TOP mRNA-encoded proteins compared to other proteins. Therefore, in response to ribosomal stress, there is a change in the translation pattern of the cell which may help restore a sufficient level of ribosomes
Super-Kamiokande atmospheric neutrinos: Status of subdominant oscillations
In the context of the recent (79.5 kTy) Super-Kamiokande atmospheric neutrino
data, we concisely review the status of muonic-tauonic flavor oscillations and
of the subdominant electron or sterile neutrino mixing, in schemes with three
or four families and one dominant mass scale. In the three-family case, where
we include the full CHOOZ spectral data, we also show, through a specific
example, that ``maximal'' violations of the one-dominant mass scale
approximation are not ruled out yet.Comment: 8 pages + 10 figure
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