2,404 research outputs found
Proteomic analysis of the rat ovary following chronic low-dose exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitously distributed endocrine-disrupting chemical and reproductive toxicant. In order to elucidate low-dose TCDD-mediated effects on reproductive or endocrine functions, female Sprague-Dawley rats were orally administered various concentrations (20, 50, or 125 ng/kg once weekly) TCDD for 29 wk. A proteomic analysis of the ovaries by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization (MALDI) tandem mass spectrometry showed distinct changes in the levels of several proteins that are relevant markers of TCDD toxicity. Serum estradiol (E2) levels of TCDD-treated animals were markedly lower than control. There were no significant differences in bone mineral density (BMD) of femurs. The body weight of the 125-ng/kg TCDD group was significantly decreased relative to control and there was also a significant reduction in absolute and relative ovarian weights. Expressions of selenium binding protein 2, glutathione S-transferase mu type 3, Lrpap1 protein, NADPH, and peptidylprolyl isomerase D were upregulated, while prohibitin and N-ethylmaleimide-sensitive factor expression levels were downregulated. Data provide further insight into the mechanisms by which TCDD disrupts ovarian function by indicating which differential protein expressions following low-dose TCDD exposure
Quark and Nucleon Self-Energy in Dense Matter
In a recent work we introduced a nonlocal version of the
Nambu--Jona-Lasinio(NJL) model that was designed to generate a quark
self-energy in Euclidean space that was similar to that obtained in lattice
simulations of QCD. In the present work we carry out related calculations in
Minkowski space, so that we can study the effects of the significant vector and
axial-vector interactions that appear in extended NJL models and which play an
important role in the study of the , and mesons. We study
the modification of the quark self-energy in the presence of matter and find
that our model reproduces the behavior of the quark condensate predicted by the
model-independent relation , where is the
pion-nucleon sigma term and is the density of nuclear matter. (Since
we do not include a model of confinement, our study is restricted to the
analysis of quark matter. We provide some discussion of the modification of the
above formula for quark matter.) The inclusion of a quark current mass leads to
a second-order phase transition for the restoration of chiral symmetry. That
restoration is about 80% at twice nuclear matter density for the model
considered in this work. We also find that the part of the quark self-energy
that is explicitly dependent upon density has a strong negative Lorentz-scalar
term and a strong positive Lorentz-vector term, which is analogous to the
self-energy found for the nucleon in nuclear matter when one makes use of the
Dirac equation for the nucleon. In this work we calculate the nucleon self
-energy in nuclear matter using our model of the quark self-energy and obtain
satisfactory results.Comment: 19 pages, 8 figures, 2 tables, revte
Genomic Prediction and QTL Mapping Using Bayesian Methods
Several genomic selection methods were applied to a data set that was simulated for the 2010 QTLMAS workshop to predict the genomic breeding values (GEBV) of the offspring generation and to map the QTL. The GEBV had an accuracy of 0.894 with very small bias. QTL were detected based on the variance of 10 SNP windows. Using a threshold chosen for a 10% chromosome-wise type-I error rate, most of the large QTL were successfully detected with few false positives. Results for both prediction of breeding values and detection of QTL were among the best among all analyses of this data set by groups across the globe. Genomic selection method BayesCπ was identified to be appropriate for the 2010 QTLMAS dataset and also applicable to real cases with similar settings
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Task 19 - Sampling, Analysis, and Vitrification Study for Thermochem's Steam Reformer Treatment Technology
The overall objective of the project is to provide support to Thermochem, Inc., in the demonstration of the steam reformer treatment technology to treat LLMW. Within this program, specific objectives include the following: (1) Analyze cerium, chlorine, and fluorine concentrations in samples from the pilot-scale steam reformer tests to determine partitioning of these elements, mass balances, and changes in concentration with time. (2) Perform experimental characterization of temperature--viscosity profiles to aid in determining vitrification viability for long-term stabilization. Additionally, calculations of viscosity will be performed for several blend combinations to complement the experimentally determined values. (3) Conduct leachability tests on the vitrified slags to aid in determining if product leachability falls within EPA guidelines and to assess the suitability of the vitrified material for long-term disposal
Combustion characteristics of oxymethylene dimethyl ether-diesel blends:An experimental investigation using a constant-volume combustion chamber
The combustion characteristics of oxymethylene dimethyl ether (OMEx) and its blends with diesel have been investigated using a multi-hole injector in a constant-volume combustion chamber. The results show OMEx addition can reduce the ignition delay, especially when blends of more than 50 vol% are used, at low chamber temperature. Two individual heat-release peaks are observed for OMEx during premixed combustion at 750 K, due to a pronounced low-temperature heat-release phase. The chamber temperature of 800 K can be regarded as a transition point for the behavior of burn duration as well as maximum ROHR peak, mostly caused by combustion regime transition from premixed- to diffusion combustion. It appears that there is an approximate linear relation between maximum ROHR peak and the time at which this peak occurs with injection pressure. The ignition delay of OMEx is almost insensitive to a decrease in ambient oxygen concentration. And the premixed ROHR profile, due to its high oxygen content, is very similar and only ignition delay and burn duration increase slightly. Additionally, comparisons of natural luminosity results for OMEx and diesel indicate that OMEx produces near-zero soot values. Luminosity is expected to be caused by chemiluminescence alone, which increases with injection pressure
Comparison of Temperature-Dependent Hadronic Current Correlation Functions Calculated in Lattice Simulations of QCD and with a Chiral Lagrangian Model
The Euclidean-time hadronic current correlation functions, and
, of pseudoscalar and vector currents have recently been
calculated in lattice simulations of QCD and have been used to obtain the
corresponding spectral functions. We have used the Nambu-Jona-Lasinio (NJL)
model to calculate such spectral functions, as well as the Euclidean-time
correlators, and have made a comparison to the lattice results for the
correlators. We find evidence for the type of temperature dependence of the NJL
coupling parameters that we have used in previous studies of the mesonic
confinement-deconfinement transition. We also see that the spectral functions
obtained when using the maximum-entropy-method (MEM) and the lattice data
differ from the spectral functions that we calculate in our chiral model.
However, our results for the Euclidean-time correlators are in general
agreement with the lattice results, with better agreement when our
temperature-dependent coupling parameters are used than when
temperature-independent parameters are used for the NJL model. We also discuss
some additional evidence for the utility of temperature-dependent coupling
parameters for the NJL model. For example, if the constituent quark mass at T=0
is in the chiral limit, the transition temperature is for the NJL model with a standard momentum cutoff parameter. (If a
Gaussian momentum cutoff is used, we find in the chiral limit,
with at T=0.) The introduction of a weak temperature dependence
for the coupling constant will move the value of into the range 150-170
MeV, which is more in accord with what is found in lattice simulations of QCD
with dynamical quarks
Sagnac Interferometer as a Speed-Meter-Type, Quantum-Nondemolition Gravitational-Wave Detector
According to quantum measurement theory, "speed meters" -- devices that
measure the momentum, or speed, of free test masses -- are immune to the
standard quantum limit (SQL). It is shown that a Sagnac-interferometer
gravitational-wave detector is a speed meter and therefore in principle it can
beat the SQL by large amounts over a wide band of frequencies. It is shown,
further, that, when one ignores optical losses, a signal-recycled Sagnac
interferometer with Fabry-Perot arm cavities has precisely the same
performance, for the same circulating light power, as the Michelson speed-meter
interferometer recently invented and studied by P. Purdue and the author. The
influence of optical losses is not studied, but it is plausible that they be
fairly unimportant for the Sagnac, as for other speed meters. With squeezed
vacuum (squeeze factor ) injected into its dark port, the
recycled Sagnac can beat the SQL by a factor over the
frequency band 10 {\rm Hz} \alt f \alt 150 {\rm Hz} using the same
circulating power kW as is used by the (quantum limited)
second-generation Advanced LIGO interferometers -- if other noise sources are
made sufficiently small. It is concluded that the Sagnac optical configuration,
with signal recycling and squeezed-vacuum injection, is an attractive candidate
for third-generation interferometric gravitational-wave detectors (LIGO-III and
EURO).Comment: 12 pages, 6 figure
An evaluation of the capability of data conversion of impression creep test
High temperature power plant components are now working far beyond their operative designed life. Establishing their in-service material properties has become a matter of significant concern for power generation companies. Advantages for the assessment of creep material properties may come from miniature specimen creep testing techniques, like impression creep testing method, which can be treated as a quasistatic non-destructive technique and requires a small volume of material that can be scooped from in-service critical components, and can produce reliable secondary creep data.
This paper presents an overview of impression creep testing method to highlight the capability in determining the minimum creep strain rate data by use of conversion relationships that relates uniaxial creep test data and impression creep test data. Stepped-load and stepped-temperature impression creep tests are also briefly described. Furthermore, the paper presents some new impression creep test data and their correlation with uniaxial data, obtained from P91, P92 and ½CrMoV steels at different stresses and temperatures. The presented data, in terms of creep strain rate against the reference uniaxial stress, are useful for calibration of impression creep testing technique and provide further comparative results for the evaluation of the reliability of the method in determining secondary creep properties
Tourmaline composition probes serpentinite-derived fluid mobility in subduction zones
Serpentinite dehydration in subduction zones plays a pivotal role in geochemical cycling on Earth. A number of geochemical studies on arc magmas have elucidated the contributions of serpentinite-derived fluids to mantle sources. However, due to complex geological overprints during subduction zone processes, discerning serpentinite signatures in exposed metamorphic rocks within fossil subduction zones remains challenging. In this study we address these difficulties through in-situ investigations of tourmaline, the geochemistry of which reflects the host environment as well as potential fluid-induced processes. The presence of zonations in tourmaline makes it an excellent recorder of consecutive geological events. Integrated major and trace elements along with in-situ boron isotopes of tourmaline from the high-pressure Sopron area (Hungary) in the Eastern Alps were used to unravel fluid action sourced from serpentinite. Despite the presence of color zoning, tourmaline in the orthogneiss (Tur-G) has low XMg [Mg/(Mg + Fe)] of ca. 0.3–0.6 and δ11B values of around −11 ‰, along with variable trace element compositions. Petrological observations and geochemical analyses suggest that the inner domains of Tur-G are of igneous origin, while the outer rims are likely affected by subsequent metamorphic events. Tourmaline in metasomatized kyanite-quartzite (Tur-K) veins exhibits distinct geochemical zoning, and preserves metamorphic cores and fluid-induced rims. The inner domains of Tur-K display low XMg (<0.6), relatively high trace element concentrations and δ11B values of less than −10 ‰, whereas the overgrowths exhibit extremely high XMg values (>0.99), low trace element concentrations and high δ11B values reaching up to +21 ‰, clearly indicating the incorporation of serpentinite-derived Mg-11B-rich fluids. Through comparison with other metamorphic and metasomatic tourmalines in (ultra)high-pressure rocks globally, we establish that tourmaline with high XMg > 0.85 and δ11B values >0 ‰ may serve as an effective proxy for detecting serpentinite-derived fluids in subduction zones
A Model for Ferromagnetic Nanograins with Discrete Electronic States
We propose a simple phenomenological model for an ultrasmall ferromagnetic
grain, formulated in terms of the grain's discrete energy levels. We compare
the model's predictions with recent measurements of the discrete tunneling
spectrum through such a grain. The model can qualitatively account for the
observed features if we assume (i) that the anisotropy energy varies among
different eigenstates of one grain, and (ii) that nonequilibrium spin
accumulation occurs.Comment: 4 pages, 2 figure
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