1,086 research outputs found
Search for decay of Eu to the first excited level of Pm using underground -ray spectrometry
The alpha decay of Eu to the first excited level of Pm
(, keV) was searched for at the HADES underground
laboratory ( m w.e.). A sample of high purity europium oxide with
mass of 303 g and a natural isotopic composition has been measured over 2232.8
h with a high energy resolution ultra-low background n-type semi-planar HPGe
detector (40 cm) with sub-micron deadlayer. The new improved half-life
limit has been set as yr at 68% C.L.
Possibilities to improve the sensitivity of the experiment, which is already
near the theoretical predictions, are discussed. New half-life limit for
decay of Eu is also set as
yr.Comment: 11 pages, 5 figures, 2 tables, 18 reference
A Survey About Nothing: Monitoring a Million Supergiants for Failed Supernovae
Extragalactic transient searches have historically been limited to looking
for the appearance of new sources such as supernovae. It is now possible to
carry out a new kind of survey that will do the opposite, that is, search for
the disappearance of massive stars. This will entail the systematic observation
of galaxies within a distance of 10 Mpc in order to watch ~10^6 supergiants.
Reaching this critical number ensures that something will occur yearly, since
these massive stars must end their lives with a core collapse within ~10^6
years. Using deep imaging and image subtraction it is possible to determine the
fates of these stars whether they end with a bang (supernova) or a whimper
(fall out of sight). Such a survey would place completely new limits on the
total rate of all core collapses, which is critical for determining the
validity of supernova models. It would also determine the properties of
supernova progenitors, better characterize poorly understood optical
transients, such as eta Carina-like mass ejections, find and characterize large
numbers of Cepheids, luminous blue variables and eclipsing binaries, and allow
the discovery of any new phenomena that inhabit this relatively unexplored
parameter space.Comment: final version, 7 pages, 5 figures, ApJ in pres
Analysis of cross-correlations between financial markets after the 2008 crisis
We analyze the cross-correlation matrix C of the index returns of the main financial markets after the 2008 crisis using methods of random matrix theory. We test the eigenvalues of C for universal properties of random matrices and find that the majority of the cross-correlation coefficients arise from randomness. We show that the eigenvector of the largest deviating eigenvalue of C represents a global market itself. We reveal that high volatility of financial markets is observed at the same times with high correlations between them which lowers the risk diversification potential even if one constructs a widely internationally diversified portfolio of stocks. We identify and compare the connection and cluster structure of markets before and after the crisis using minimal spanning and ultrametric hierarchical trees. We find that after the crisis, the co-movement degree of the markets increases. We also highlight the key financial markets of pre and post crisis using main centrality measures and analyze the changes. We repeat the study using rank correlation and compare the differences. Further implications are discussed. © 2013 Elsevier B.V. All rights reserved
Impact of donation mode on the proportion and function of T lymphocytes in the liver
Background
Liver T-cells respond to the inflammatory insult generated during organ procurement and contribute to the injury following reperfusion. The mode of liver donation alters various metabolic and inflammatory pathways but the way it affects intrahepatic T-cells is still unclear.
Methods
We investigated the modifications occurring in the proportion and function of T-cells during liver procurement for transplantation. We isolated hepatic mononuclear cells (HMC) from liver perfusate of living donors (LD) and donors after brain death (DBD) or cardiac death (DCD) and assessed the frequency of T-cell subsets, their cytokine secretion profile and CD8 T-cell cytotoxicity function, responsiveness to a danger associated molecular pattern (High Mobility Group Box1, HMGB1) and association with donor and recipient clinical parameters and immediate graft outcome.
Results
We found that T-cells in healthy human livers were enriched in memory CD8 T-cells exhibiting a phenotype of non-circulating tissue-associated lymphocytes, functionally dominated by more cytotoxicity and IFN-Îł-production in DBD donors, including upon activation by HMGB1 and correlating with peak of post-transplant AST. This liver-specific pattern of CD8 T-cell was prominent in DBD livers compared to DCD and LD livers suggesting that it was influenced by events surrounding brain death, prior to retrieval.
Conclusion
Mode of liver donation can affect liver T-cells with increased liver damage in DBD donors. These findings may be relevant in designing therapeutic strategies aimed at organ optimization prior to transplantation
The Concordance Cosmic Star Formation Rate: Implications from and for the Supernova Neutrino and Gamma Ray Backgrounds
We constrain the Cosmic Star Formation Rate (CSFR) by requiring that massive
stars produce the observed UV, optical, and IR light while at the same time not
overproduce the Diffuse Supernova Neutrino Background as bounded by
Super-Kamiokande. With the massive star component so constrained we then show
that a reasonable choice of stellar Initial Mass Function and other parameters
results in SNIa rates and iron yields in good agreement with data. In this way
we define a `concordance' CSFR that predicts the optical SNII rate and the SNIa
contribution to the MeV Cosmic Gamma-Ray Background. The CSFR constrained to
reproduce these and other proxies of intermediate and massive star formation is
more clearly delineated than if it were measured by any one technique and has
the following testable consequences: (1) SNIa contribute only a small fraction
of the MeV Cosmic Gamma-Ray Background, (2) massive star core-collapse is
nearly always accompanied by a successful optical SNII, and (3) the Diffuse
Supernova Neutrino Background is tantalizingly close to detectability.Comment: Improved discussion. Version accepted for publication in JCA
Effects of slaughter age and muscle type on meat quality characteristics of Eastern Anatolian Red bulls
The effects of slaughter age and muscle type on meat quality properties of
Eastern Anatolian Red (EAR) bulls (n=46) were investigated in the present
study. Forty-six EAR bulls were slaughtered at 15, 17, 19, 25 and 27 months.
Meat samples were taken from longissimus dorsi (LD) and gluteus medius (GM)
muscles obtained from the carcasses at 24 h post-mortem. Meat color
parameters were significantly affected by slaughter age. Older animals (19,
25 and 27 months of age) possessed higher L*, a* and
HÂ values than those of younger animals (15Â and 17Â months of age). LD muscle
had higher L* and a* values than those of GM muscles. The influences
of slaughter age and muscle type on the proportions of dry matter, ether
extract, crude ash and crude protein were not significant in the present study.
The influence of slaughter age on the tenderness, acceptability, juiciness,
number of chews and WarnerâBratzler shear (WBS) values were found to be
significant. Tenderness, juiciness, flavor intensity and acceptability
increased until 19Â months of age, and then increase in age resulted in lower
tenderness, flavor intensity and acceptability scores. Cooking yield
significantly increased depending on the increase of age. WBS and cooking
yield values from the LD were higher than that of the GM muscle. Textural
characteristics such as hardness, springiness, cohesiveness, gumminess,
chewiness and resilience were not affected by slaughter age, but muscles had
a significant influence on hardness, gumminess, chewiness and resilience. In
conclusion, most eating quality characteristics and color parameters were
positively influenced by slaughter age.</p
End-to-End Joint Antenna Selection Strategy and Distributed Compress and Forward Strategy for Relay Channels
Multi-hop relay channels use multiple relay stages, each with multiple relay
nodes, to facilitate communication between a source and destination.
Previously, distributed space-time codes were proposed to maximize the
achievable diversity-multiplexing tradeoff, however, they fail to achieve all
the points of the optimal diversity-multiplexing tradeoff. In the presence of a
low-rate feedback link from the destination to each relay stage and the source,
this paper proposes an end-to-end antenna selection (EEAS) strategy as an
alternative to distributed space-time codes. The EEAS strategy uses a subset of
antennas of each relay stage for transmission of the source signal to the
destination with amplify and forwarding at each relay stage. The subsets are
chosen such that they maximize the end-to-end mutual information at the
destination. The EEAS strategy achieves the corner points of the optimal
diversity-multiplexing tradeoff (corresponding to maximum diversity gain and
maximum multiplexing gain) and achieves better diversity gain at intermediate
values of multiplexing gain, versus the best known distributed space-time
coding strategies. A distributed compress and forward (CF) strategy is also
proposed to achieve all points of the optimal diversity-multiplexing tradeoff
for a two-hop relay channel with multiple relay nodes.Comment: Accepted for publication in the special issue on cooperative
communication in the Eurasip Journal on Wireless Communication and Networkin
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