580 research outputs found
The Response of Lake Pontchartrain Fish Assemblages to Hurricanes Katrina and Rita
To assess possible impacts on Lake Pontchartrain fishes from the 2005 hurricanes, we 45 compared trawl, beach seine, and gillnet collections taken before (2000-2003, 2005) and after 46 (2006-2009) to determine if significant assemblage changes occurred. We also compared basic 47 environmental variables to test for hurricane-related changes. Significant post-hurricane changes 48 in fish assemblages occurred in trawl (ANOSIM, R \u3c 0.090, p \u3c 0.05) and beach seine 49 (ANOSIM, R \u3c 0.120, p \u3c 0.05) collections across all seasons. Gillnet assemblages exhibited 50 changes in only one season (ANOSIM, R = 0.045, p \u3c 0.05). These consistently low global R 51 values (all R \u3c 0.120) across all gears suggest only minor compositional changes in species. 52 When peak abundance periods were compared for individual species, Gulf menhaden 53 (Brevoortia patronus) declined in trawl collections after the hurricanes (Friedmanâs test, Ï2 = 54 6.00, p = 0.014) but increased in gillnet collections (Friedmanâs test, Ï2=5.00, p = 0.025). 55 Hardhead catfish (Ariopsis felis) increased in trawl collections, but Gulf pipefish (Syngnathus 56 scovelli), naked gobies (Gobiosoma bosc), and rough silverside (Membras martinica) all 57 declined in beach seine samples and Atlantic croakers (M. undulatus), Spanish mackerel 58 (Scomberomorus maculatus), and sand seatrout (Cynoscion arenarius) all declined in gillnet 59 samples. In general, salinity increased and water clarity and dissolved oxygen decreased after 60 the hurricanes. While the overall composition of Lake Pontchartrain fish assemblages remains 61 stable, the significant decline of some species and changes in certain environmental variables are 62 cause for concern. Future monitoring should determine if all elements of this estuary will 63 recover from these impacts
On the origin of the A and B electronic Raman scattering peaks in the superconducting state of YBaCuO
The electronic Raman scattering has been investigated in optimally oxygen
doped YBaCuO single crystals as well as in crystals
with non-magnetic, Zn, and magnetic, Ni, impurities. We found that the
intensity of the A peak is impurity independent and their energy to
ratio is almost constant (). Moreover, the
signal at the B channel is completely smeared out when non-magnetic Zn
impurities are present. These results are qualitatively interpreted in terms of
the Zeyher and Greco's theory that relates the electronic Raman scattering in
the A and B channels to \textit{d}-CDW and superconducting order
parameters fluctuations, respectively.Comment: Submited to Phys. Rev. Let
Inhomogeneously doped two-leg ladder systems
A chemical potential difference between the legs of a two-leg ladder is found
to be harmful for Cooper pairing. The instability of superconductivity in such
systems is analyzed by compairing results of various analytical and numerical
methods. Within a strong coupling approach for the t-J model, supplemented by
exact numerical diagonalization, hole binding is found unstable beyond a
finite, critical chemical potential difference. The spinon-holon mean field
theory for the t-J model shows a clear reduction of the the BCS gaps upon
increasing the chemical potential difference leading to a breakdown of
superconductivity. Based on a renormalization group approach and Abelian
bosonization, the doping dependent phase diagram for the weakly interacting
Hubbard model with different chemical potentials was determined.Comment: Revtex4, 11 pages, 7 figure
Functional proteomics of nonalcoholic steatohepatitis: mitochondrial proteins as targets of S-adenosylmethionine
Recent work shows that S-adenosylmethionine (AdoMet) helps maintain normal liver function as chronic hepatic deficiency results in spontaneous development of steatohepatitis and hepatocellular carcinoma. The mechanisms by which these nontraditional functions of AdoMet occur are unknown. Here, we use knockout mice deficient in hepatic AdoMet synthesis (MAT1A(-/-)) to study the proteome of the liver during the development of steatohepatitis. One hundred and seventeen protein spots, differentially expressed during the development of steatohepatitis, were selected and identified by peptide mass fingerprinting. Among them, 12 proteins were found to be affected from birth, when MAT1A(-/-) expression is switched on in WT mouse liver, to the rise of histological lesions, which occurs at approximately 8 months. Of the 12 proteins, 4 [prohibitin 1 (PHB1), cytochrome c oxidase I and II, and ATPase beta-subunit] have known roles in mitochondrial function. We show that the alteration in expression of PHB1 correlates with a loss of mitochondrial function. Experiments in isolated rat hepatocytes indicate that AdoMet regulates PHB1 content, thus suggesting ways by which steatohepatitis may be induced. Importantly, we found the expression of these mitochondrial proteins was abnormal in obob mice and obese patients who are at risk for nonalcoholic steatohepatitis
Methionine adenosyltransferase II beta subunit gene expression provides a proliferative advantage in human hepatoma
BACKGROUND & AIMS: Of the 2 genes (MAT1A, MAT2A) encoding methionine adenosyltransferase, the enzyme that synthesizes S-adenosylmethionine, MAT1A, is expressed in liver, whereas MAT2A is expressed in extrahepatic tissues. In liver, MAT2A expression associates with growth, dedifferentiation, and cancer. Here, we identified the beta subunit as a regulator of proliferation in human hepatoma cell lines. The beta subunit has been cloned and shown to lower the K(m) of methionine adenosyltransferase II alpha2 (the MAT2A product) for methionine and to render the enzyme more susceptible to S-adenosylmethionine inhibition.
METHODS: Methionine adenosyltransferase II alpha2 and beta subunit expression was analyzed in human and rat liver and hepatoma cell lines and their interaction studied in HuH7 cells. beta Subunit expression was up- and down-regulated in human hepatoma cell lines and the effect on DNA synthesis determined.
RESULTS: We found that beta subunit is expressed in rat extrahepatic tissues but not in normal liver. In human liver, beta subunit expression associates with cirrhosis and hepatoma. beta Subunit is expressed in most (HepG2, PLC, and Hep3B) but not all (HuH7) hepatoma cell lines. Transfection of beta subunit reduced S-adenosylmethionine content and stimulated DNA synthesis in HuH7 cells, whereas down-regulation of beta subunit expression diminished DNA synthesis in HepG2. The interaction between methionine adenosyltransferase II alpha2 and beta subunit was demonstrated in HuH7 cells.
CONCLUSIONS: Our findings indicate that beta subunit associates with cirrhosis and cancer providing a proliferative advantage in hepatoma cells through its interaction with methionine adenosyltransferase II alpha2 and down-regulation of S-adenosylmethionine levels
Impurity state in the vortex core of d-wave superconductors: Anderson impurity model versus unitary impurity model
Using an extended Anderson/Kondo impurity model to describe the magnetic
moments around an impurity doped in high- d-wave cuprates and in
the framework of the slave-boson meanfield approach, we study numerically the
impurity state in the vortex core by exact diagonalization of the
well-established Bogoliubov-de Gennes equations. The low-energy impurity state
is found to be good agreement with scanning tunnelingmicroscopy observation.
After pinning a vortex on the impurity site, we compare the unitary impurity
model with the extended Anderson impurity model by examining the effect of the
magnetic field on the impurity state. We find that the impurity resonance in
the unitary impurity model is strongly suppressed by the vortex; while it is
insensitive to the field in the extended Anderson impurity model.Comment: 8 pages, 3 figure
Adaptive Effects of Static Muscular Strength Training
The trend towards mechanization of tasks involving manual labor has increased the importance of static muscular activity (isometric contractions). Information about the physiological reaction to static muscular activity has been increasing rapidly over the last few decades, but little information has been developed on the adaptive responses to chronic exposure to static muscular activity. This paper reports the results of an experiment on adaptive cardiovascular changes to a five week training program in which the % MVC was maintained at 50% for the entire program, i.e., weekly adjustments were made for increases in strength. The only significant change in the cardiovascular response to the training program was an increase in the rate at which the heart rate increased during periods of contraction. The average level of heart rate, systolic blood pressure and diastolic blood pressure did not change with training. Neither the systolic or diastolic blood pressure modified their rates of change due to training. Significant changes in strength and endurance hold capacity were also noted.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Entropy-Corrected New Agegraphic Dark Energy Model in Horava-Lifshitz Gravity
In this work, we have considered the entropy-corrected new agegraphic dark
energy (ECNADE) model in Horava-Lifshitz gravity in FRW universe. We have
discussed the correspondence between ECNADE and other dark energy models such
as DBI-essence,Yang-Mills dark energy, Chameleon field, Non-linear
electrodynamics field and hessence dark energy in the context of
Horava-Lifshitz gravity and reconstructed the potentials and the dynamics of
the scalar field theory which describe the ECNADE.Comment: 12 page
Constrained Supersymmetric Flipped SU(5) GUT Phenomenology
We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT
model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are
constrained to be universal at some input scale, , above the GUT scale,
. We analyze the parameter space of CFSU(5) assuming that the lightest
supersymmetric particle (LSP) provides the cosmological cold dark matter,
paying careful attention to the matching of parameters at the GUT scale. We
first display some specific examples of the evolutions of the SSB parameters
that exhibit some generic features. Specifically, we note that the relationship
between the masses of the lightest neutralino and the lighter stau is sensitive
to , as is the relationship between the neutralino mass and the masses
of the heavier Higgs bosons. For these reasons, prominent features in generic
planes such as coannihilation strips and rapid-annihilation
funnels are also sensitive to , as we illustrate for several cases with
tan(beta)=10 and 55. However, these features do not necessarily disappear at
large , unlike the case in the minimal conventional SU(5) GUT. Our
results are relatively insensitive to neutrino masses.Comment: 23 pages, 8 figures; (v2) added explanations and corrected typos,
version to appear in EPJ
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
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