501 research outputs found

    Prospects for probing the gluon density in protons using heavy quarkonium hadroproduction

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    We examine carefully bottomonia hadroproduction in proton colliders, especially focusing on the LHC, as a way of probing the gluon density in protons. To this end we develop some previous work, getting quantitative predictions and concluding that our proposal can be useful to perform consistency checks of the parameterization sets of different parton distribution functions.Comment: LaTeX, 14 pages, 6 EPS figure

    Magnetic Phase Transition of the Perovskite-type Ti Oxides

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    Properties and mechanism of the magnetic phase transition of the perovskite-type Ti oxides, which is driven by the Ti-O-Ti bond angle distortion, are studied theoretically by using the effective spin and pseudo-spin Hamiltonian with strong Coulomb repulsion. It is shown that the A-type antiferromagnetic(AFM(A)) to ferromagnetic(FM) phase transition occurs as the Ti-O-Ti bond angle is decreased. Through this phase transition, the orbital state is hardly changed so that the spin-exchange coupling along the c-axis changes nearly continuously from positive to negative and takes approximately zero at the phase boundary. The resultant strong two-dimensionality in the spin coupling causes a rapid suppression of the critical temperature as is observed experimentally.Comment: 9 pages, 5 figure

    Magnetic and Orbital States and Their Phase Transition of the Perovskite-Type Ti Oxides: Strong Coupling Approach

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    The properties and mechanism of the magnetic phase transition of the perovskite-type Ti oxides, which is driven by the Ti-O-Ti bond angle distortion, are studied theoretically by using the effective spin and pseudospin Hamiltonian with strong Coulomb repulsion. It is shown that the A-type antiferromagnetic (AFM(A)) to ferromagnetic (FM) phase transition occurs as the Ti-O-Ti bond angle is decreased. Through this phase transition, the orbital state changes only little whereas the spin-exchange coupling along the c-axis is expected to change from positive to negative nearly continuously and approaches zero at the phase boundary. The resultant strong two-dimensionality in the spin coupling causes rapid suppression of the critical temperature, as observed experimentally. It may induce large quantum fluctuations in this region.Comment: 13 pages, 15 figure

    Infrared Spectroscopy of Nearby Radio Active Elliptical Galaxies

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    In preparation for a study of their circumnuclear gas we have surveyed 60% of a complete sample of elliptical galaxies within 75 Mpc that are radio sources. Some 20% of our nuclear spectra have infrared emission lines, mostly Paschen lines, Brackett γ, and [Fe II]. We consider the influence of radio power and black hole mass in relation to the spectra. Access to the spectra is provided here as a community resource

    ROS Promote Epigenetic Remodeling and Cardiac Dysfunction in Offspring Following Maternal Engineered Nanomaterial (ENM) Exposure

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    Background: Nano-titanium dioxide (nano-TiO2) is amongst the most widely utilized engineered nanomaterials (ENMs). However, little is known regarding the consequences maternal ENM inhalation exposure has on growing progeny during gestation. ENM inhalation exposure has been reported to decrease mitochondrial bioenergetics and cardiac function, though the mechanisms responsible are poorly understood. Reactive oxygen species (ROS) are increased as a result of ENM inhalation exposure, but it is unclear whether they impact fetal reprogramming. The purpose of this study was to determine whether maternal ENM inhalation exposure influences progeny cardiac development and epigenomic remodeling. Results: Pregnant FVB dams were exposed to nano-TiO2 aerosols with a mass concentration of 12.09 ± 0.26 mg/m3 starting at gestational day five (GD 5), for 6 h over 6 non-consecutive days. Aerosol size distribution measurements indicated an aerodynamic count median diameter (CMD) of 156 nm with a geometric standard deviation (GSD) of 1.70. Echocardiographic imaging was used to assess cardiac function in maternal, fetal (GD 15), and young adult (11 weeks) animals. Electron transport chain (ETC) complex activities, mitochondrial size, complexity, and respiration were evaluated, along with 5-methylcytosine, Dnmt1 protein expression, and Hif1α activity. Cardiac functional analyses revealed a 43% increase in left ventricular mass and 25% decrease in cardiac output (fetal), with an 18% decrease in fractional shortening (young adult). In fetal pups, hydrogen peroxide (H2O2) levels were significantly increased (~ 10 fold) with a subsequent decrease in expression of the antioxidant enzyme, phospholipid hydroperoxide glutathione peroxidase (GPx4). ETC complex activity IV was decreased by 68 and 46% in fetal and young adult cardiac mitochondria, respectively. DNA methylation was significantly increased in fetal pups following exposure, along with increased Hif1α activity and Dnmt1 protein expression. Mitochondrial ultrastructure, including increased size, was observed at both fetal and young adult stages following maternal exposure. Conclusions: Maternal inhalation exposure to nano-TiO2 results in adverse effects on cardiac function that are associated with increased H2O2 levels and dysregulation of the Hif1α/Dnmt1 regulatory axis in fetal offspring. Our findings suggest a distinct interplay between ROS and epigenetic remodeling that leads to sustained cardiac contractile dysfunction in growing and young adult offspring following maternal ENM inhalation exposure

    Lead Bullet Fragments in Venison from Rifle-Killed Deer: Potential for Human Dietary Exposure

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    Human consumers of wildlife killed with lead ammunition may be exposed to health risks associated with lead ingestion. This hypothesis is based on published studies showing elevated blood lead concentrations in subsistence hunter populations, retention of ammunition residues in the tissues of hunter-killed animals, and systemic, cognitive, and behavioral disorders associated with human lead body burdens once considered safe. Our objective was to determine the incidence and bioavailability of lead bullet fragments in hunter-killed venison, a widely-eaten food among hunters and their families. We radiographed 30 eviscerated carcasses of White-tailed Deer (Odocoileus virginianus) shot by hunters with standard lead-core, copper-jacketed bullets under normal hunting conditions. All carcasses showed metal fragments (geometric mean = 136 fragments, range = 15–409) and widespread fragment dispersion. We took each carcass to a separate meat processor and fluoroscopically scanned the resulting meat packages; fluoroscopy revealed metal fragments in the ground meat packages of 24 (80%) of the 30 deer; 32% of 234 ground meat packages contained at least one fragment. Fragments were identified as lead by ICP in 93% of 27 samples. Isotope ratios of lead in meat matched the ratios of bullets, and differed from background lead in bone. We fed fragment-containing venison to four pigs to test bioavailability; four controls received venison without fragments from the same deer. Mean blood lead concentrations in pigs peaked at 2.29 µg/dL (maximum 3.8 µg/dL) 2 days following ingestion of fragment-containing venison, significantly higher than the 0.63 µg/dL averaged by controls. We conclude that people risk exposure to bioavailable lead from bullet fragments when they eat venison from deer killed with standard lead-based rifle bullets and processed under normal procedures. At risk in the U.S. are some ten million hunters, their families, and low-income beneficiaries of venison donations

    Potential Impact of the Development of Lignite Reserves on Water Resources of East Texas

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    This study was conducted for the Office of Water Resources Research and Technology in the U.S. Department of the Interior by the Texas Engineering Experiment Station at Texas A&M University. The project was concerned with identifying potential adverse effects of lignite strip mining and lignite utilization on the hydrology and water quality of the area. Both field and desk studies were conducted to evaluate the potential impact of lignite development on water resources of the area. Field studies included (1) monthly water sampling for a one-year period of streams, lakes and wells near the strip-mined areas at Fairfield and Rockdale and at control stations located away from the lignite development; (2) leaching studies of the lignite and overburden at Fairfield and Rockdale; (3) precipitation samples collected under the airborne waste plume from the lignite-fueled electric generating plant at Fairfield; and (4) a limited trace element enrichment study in the soils around the plant at Fairfield. Potential lignite reserves, as defined by the Bureau of Economic Geology, include about 41 percent of the outcrop area of the Wilcox Aquifer. Strip mining can change the hydrologic characteristics of the area and full development of the near-surface lignite reserves in east and east central Texas could have a significant impact on the groundwater resources of the region. Changes in the recharge rate of the Wilcox aquifer should be considered when identifying new lignite deposits for development. Also hydrologic characteristics should be considered when developing reclamation plans for the spoil area. Lignite-fired power plants cause environmental modifications of considerable magnitude and consume a significant quantity of water. During the 35-year expected life of a l,000-megawatt, lignite-fired power plant, about 21,000 acres of land would typically be strip mined. Approximately 25 percent of the identified near-surface lignite deposits are committed to existing and presently planned lignite-fired power plants in Texas. The Development of deep-basin lignite deposits in the near future appear inevitable. Lignite can contain elevated concentrations of certain trace elements and power plants tend to concentrate these elements. A l,OOO-megawatt plant requires approximately six million tons of lignite per year. When the lignite is fired at the plant some trace metals are concentrated in the fly ash (arsenic, iron, manganese and lead), while others are discharged from the stack primarily as a vapor (mercury and selenium). Improper handling and disposal of fly ash could result in pollution of water supplies. Precipitation samples collected at Fairfield under the airborne waste plume from the Big Brown plant had elevated concentrations of chromium, iron, manganese, selenium and phosphate when compared to background precipitation samples. A trace element enrichment study of the soils around the plant should be conducted to monitor the concentrations of those elements that could adversely affect the plant and animal life of the area. Small surface streams near Rockdale and Fairfield had elevated levels of zinc, selenium, manganese and sulfate as compared to other surface waters observed in the study. Strip mining or power generation was probably not the primary source of the elevated levels of these parameters. A water quality study should be initiated to accurately identify the source of these elevated parameters. Water quality in the cooling lakes at the Alcoa plant near Rockdale and the Big Brown plant near Fairfield was generally good. Highest observed values of many of the surface water quality parameters were in the spoil lake in the strip-mined area at Alcoa. Since there appears to be a direct hydraulic connection between water in the spoil lake and the shallow groundwater aquifer in the area, poor water quality in the lake could adversely affect the groundwater. Additional groundwater studies were recommended for both the Rockdale area and the Fairfield area

    Anharmonic double-phonon excitations in the interacting boson model

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    Double-γ\gamma vibrations in deformed nuclei are analyzed in the context of the interacting boson model. A simple extension of the original version of the model towards higher-order interactions is required to explain the observed anharmonicities of nuclear vibrations. The influence of three- and four-body interactions on the moments of inertia of ground- and γ\gamma-bands, and on the relative position of single-γ\gamma and double-γ\gamma bands is studied in detail. As an example of a realistic calculation, spectra and transitions of the highly γ\gamma-anharmonic nuclei 164^{164}Dy, 166^{166}Er, and 168^{168}Er are interpreted in this approach.Comment: 38 pages, TeX (ReVTeX). 15 ps figures. Submitted to Phys. Rev.

    A first estimate of triply heavy baryon masses from the pNRQCD perturbative static potential

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    Within pNRQCD we compute the masses of spin-averaged triply heavy baryons using the now-available NNLO pNRQCD potentials and three-body variational approach. We focus in particular on the role of the purely three-body interaction in perturbation theory. This we find to be reasonably small and of the order 25 MeV Our prediction for the Omega_ccc baryon mass is 4900(250) in keeping with other approaches. We propose to search for this hitherto unobserved state at B factories by examining the end point of the recoil spectrum against triple charm.Comment: 18 figures, 21 page

    Primary gliosarcoma: key clinical and pathologic distinctions from glioblastoma with implications as a unique oncologic entity

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    This report presents the historical experience, clinical presentation, treatment, prognosis, and pathogenesis of gliosarcoma described to date in the English literature. PubMed query of term “gliosarcoma” was performed, followed by a rigorous review of cited literature. Articles selected for analysis included: (1) case reports of gliosarcoma, (2) review articles of gliosarcoma, and (3) studies of the pathogenesis or genetics of gliosarcoma in humans. Our review identified 219 cases of gliosarcoma in 34 reports and eight articles addressing the pathogenesis. Survival in larger series ranged 4–11.5 months. Features unique to gliosarcoma compared to glioblastoma (GBM) include their temporal lobe predilection, potential to appear similar to a meningioma at surgery, repeated reports of extracranial metastases, and infrequency of EGFR mutations. Published experience is limited to small case series, and the pathogenesis remains unclear. Clinical and pathologic characteristics distinct from GBM suggest that they may warrant specific treatment, separate from conventional GBM therapy
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