3,517 research outputs found
Subchronic Hepatotoxicity Evaluation of 2,3,4,6-Tetrachlorophenol in Sprague Dawley Rats
Male Sprague Dawley rats were exposed to 2,3,4,6-tetrachlorophenol (TCP) for 5 days, 2 weeks, 4 weeks, or 13 weeks. TCP was administered by gavage at doses of 0, 10, 25, 50, 100, or 200 mg/kg/day. Endpoints evaluated included clinical observations, body weights, liver weights, serum chemistry, blood TCP, gross pathology, and liver histopathology. There were no TCP exposure-related clinical signs of toxicity. Mean body weight decreased 12–22% compared to control in the 100 and 200 mg/kg/day groups. Serum ALT concentrations were increased in rats of the 200 mg/k/day. Liver weight increases were both dose- and exposure time-related and statistically significant at ≥25 mg/kg/day. Incidence and severity of centrilobular hepatocytic vacuolation, hepatocyte hypertrophy, and single cell hepatocytic necrosis were related to dose and exposure time. Following 13 weeks of exposure, bile duct hyperplasia and centrilobular and/or periportal fibrosis were observed in rats primarily of the highest TCP dose group. Blood TCP concentrations increased with dose and at 13 weeks ranged from 1.3 to 8.5 μg/mL (10 to 200 mg/kg/day). A NOAEL of 10 mg/kg/day was selected based on the statistically significant incidence of hepatocyte hypertrophy at doses ≥25 mg/kg/day
Spectral Correlation in Incommensurate Multi-Walled Carbon Nanotubes
We investigate the energy spectra of clean incommensurate double-walled
carbon nanotubes, and find that the overall spectral properties are described
by the so-called critical statistics of Anderson metal-insulator transition. In
the energy spectra, there exist three different regimes characterized by
Wigner-Dyson, Poisson, and semi-Poisson distributions. This feature implies
that the electron transport in incommensurate multi-walled nanotubes can be
either diffusive, ballistic, or intermediate between them, depending on the
position of the Fermi energy.Comment: final version to appear in Phys. Rev. Let
Relativistic quantum dynamics in strong fields: Photon emission from heavy, few-electron ions
Recent progress in the study of the photon emission from highly-charged heavy
ions is reviewed. These investigations show that high- ions provide a unique
tool for improving the understanding of the electron-electron and
electron-photon interaction in the presence of strong fields. Apart from the
bound-state transitions, which are accurately described in the framework of
Quantum Electrodynamics, much information has been obtained also from the
radiative capture of (quasi-) free electrons by high- ions. Many features in
the observed spectra hereby confirm the inherently relativistic behavior of
even the simplest compound quantum systems in Nature.Comment: Version 18/11/0
Albarella future – zero carbon emission
Climate warming is setting requirements on research also in the agronomic and forest fields. The soil and vegetation are available as carbon sinks. Ecosystems under high exploitation lost part of their carbon. It is possible to recover this carbon from the air with natural processes and to return it to the land. Besides, global warming requires a change in mentality that moves into the replacement of fossil fuels with other energy sources. In this perspective, the island of Albarella, with its environment and economic activities, represents an attractive miniature model of the planet Earth. For this design, we estimated (Vensim simulation) the emissions and storage of CO2 equivalent of the whole island. Then, with the idea of acting on natural ecosystems to make them more active in carbon storage, we analyzed two vegetation series from the forest to the sea, one located in the nearby natural reserve of Porto Caleri, and one on the island of Albarella. The investigation concerns the soil carbon storage and the quality and quantity of populations of arthropods, bacteria, and fungi as well. The biodiversity of artificial environments resulted in higher than that of natural habitats, opening a debate. Acting in different ways on the substitution of fuels, we obtained scenarios with decreasing emissions, from consumerist without substitution of fuels, realistic with 15% of replacement by solar energy, and sustainable with zero use of fossil energy and all the island electricity produced through photovoltaic panels
High-resolution X-ray spectroscopy and imaging of supernova remnant N132D
The observation of the supernova remnant N132D by the scientific instruments
on board the XMM-Newton satellite is presented. The X-rays from N132D are
dispersed into a detailed line-rich spectrum using the Reflection Grating
Spectrometers. Spectral lines of C, N, O, Ne, Mg, Si, S, and Fe are identified.
Images of the remnant, in narrow wavelength bands, produced by the European
Photon Imaging Cameras reveal a complex spatial structure of the ionic
distribution. While K-shell Fe emission seems to originate near the centre, all
of the other ions are observed along the shell. A high O VII / O VIII emission
ratio is detected on the northeastern edge of the remnant. This can be a sign
of hot ionising conditions, or it can reflect relatively cool gas. Spectral
fitting of the CCD spectrum suggests high temperatures in this region, but a
detailed analysis of the atomic processes involved in producing the O VII
spectral lines leads to the conclusion that the intensities of these lines
alone cannot provide a conclusive distinction between the two scenarios.Comment: To appear in A&A Letters, 365 (2001
River Influences on Shelf Ecosystems: Introduction and Synthesis
River Influences on Shelf Ecosystems (RISE) is the first comprehensive interdisciplinary study of the rates and dynamics governing the mixing of river and coastal waters in an eastern boundary current system, as well as the effects of the resultant plume on phytoplankton standing stocks, growth and grazing rates, and community structure. The RISE Special Volume presents results deduced from four field studies and two different numerical model applications, including an ecosystem model, on the buoyant plume originating from the Columbia River. This introductory paper provides background information on variability during RISE field efforts as well as a synthesis of results, with particular attention to the questions and hypotheses that motivated this research. RISE studies have shown that the maximum mixing of Columbia River and ocean water occurs primarily near plume liftoff inside the estuary and in the near field of the plume. Most plume nitrate originates from upwelled shelf water, and plume phytoplankton species are typically the same as those found in the adjacent coastal ocean. River-supplied nitrate can help maintain the ecosystem during periods of delayed upwelling. The plume inhibits iron limitation, but nitrate limitation is observed in aging plumes. The plume also has significant effects on rates of primary productivity and growth (higher in new plume water) and microzooplankton grazing (lower in the plume near field and north of the river mouth); macrozooplankton concentration (enhanced at plume fronts); offshelf chlorophyll export; as well as the development of a chlorophyll ?shadow zone? off northern Oregon
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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