995 research outputs found
Characterization and washability studies of raw coal from the Little Tonzona Field, Alaska
Coal occurs in an isolated exposure of Tertiary, non-marine sedimentary rocks
along the southwest bank of the Little Tonzona River, near Farewell, Alaska. The Little Tonzona River coal field is located approximately 150 air miles northwest of Anchorage, Alaska, and 210 air miles southwest of Fairbanks, Alaska; near the boundaries of Denali National Park. The Alaska Railroad and the Parks Highway are approximately 100 air miles from the coal field at their nearest point. The village of McGrath, on the Kuskokwim River, is located approximately 90 miles to the west (1).
An impressive outcrop of coal-bearing Tertiary sediments is exposed for a distance
of more than 275 feet on the west bank of the Little Tonzona River (Figure 1). More than
seven coal beds, ranging in thickness from 3 feet ta 30 feet, with a cumulative thickness of
over 134 feet, are interbedded with clay beds up to 40 feet thick. The clays are fine textured,
extremely plastic, light grey to nearly white bentonites andlor tonsteins.
Doyon Ltd., an ANSCA Native Corporation, holds land selections covering the
inferred limits of the coal field. During 1980 and 1981, Doyon entered into exploration
agreements with McIntyre Mines Inc. of Nevada. The two season exploration program
took place from June 1,1980 through August 22,1980 and from May 27,1981 through August
22, 1981. During the 1980 field season, geologic mapping, prospecting, stratigraphy,
trenching and bulk sampling of all coal outcrops were performed. This produced a total of
34 samples, which were taken for analysis. In 1981, six diamond drill holes with a
cumulative length of 2,935 feet were completed. Core recovery was close to 90%, and a total
of 147 coal samples, which represented 802.8 cumulative feet of coal, were taken for
analysis.
The exploration program confirmed a strike length of over 3 miles to the southwest
from the main river bank exposure. Northward extension is unknown at this time.
Although outcrop exposure is poor away from the river banks, burnout zones resulting from
past coal bed fires form a resistant, recognizable on strike feature in the relatively
unindurated Tertialy sequence. The appearance of these burnout zones along strike is
often the only surface indication of the buried coal-bearing strata. Well preserved plant
fossil impressions in the baked clays date the deposit as probable Miocene (2).
Coal characterization and washability studies were performed on all coal samples
by the Mineral Industry Research Laboratory of the University of Alaska Fairbanks. This
work was conducted under the direction of Dr. P.D. Rao, Professor of Coal Technology.This study was conducted under the sponsorship of McIntyre Mines Ltd
Energy Release During Slow Long Duration Flares Observed by RHESSI
Slow Long Duration Events (SLDEs) are flares characterized by long duration
of rising phase. In many such cases impulsive phase is weak with lack of
typical short-lasting pulses. Instead of that smooth, long-lasting Hard X-ray
(HXR) emission is observed. We analysed hard X-ray emission and morphology of
six selected SLDEs. In our analysis we utilized data from RHESSI and GOES
satellites. Physical parameters of HXR sources were obtained from imaging
spectroscopy and were used for the energy balance analysis. Characteristic time
of heating rate decrease, after reaching its maximum value, is very long, which
explains long rising phase of these flares.Comment: Accepted for publication in Solar Physic
Modern nuclear force predictions for the neutron-deuteron scattering lengths
The nd doublet and quartet scattering lengths have been calculated based on
the modern NN and 3N interactions. We also studied the effect of the
electromagnetic interactions in the form introduced in AV18. Switching them off
for the various nuclear force models leads to shifts of up to +0.04 fm for
doublet scattering length, which is significant for present day standards. The
electromagnetic effects have also a noticeable effect on quartet scattering
length, which otherwise is extremely stable under the exchange of the nuclear
forces. For the current nuclear force models there is a strong scatter of the
3H binding energy and the doublet scattering length values around an averaged
straight line (Phillips line). This allows to use doublet scattering length and
the 3H binding energy as independent low energy observables.Comment: 16 pages, 1 table, 4 ps figure
Perceptual Pluralism
Perceptual systems respond to proximal stimuli by forming mental representations of distal stimuli. A central goal for the philosophy of perception is to characterize the representations delivered by perceptual systems. It may be that all perceptual representations are in some way proprietarily perceptual and differ from the representational format of thought (Dretske 1981; Carey 2009; Burge 2010; Block ms.). Or it may instead be that perception and cognition always trade in the same code (Prinz 2002; Pylyshyn 2003). This paper rejects both approaches in favor of perceptual pluralism, the thesis that perception delivers a multiplicity of representational formats, some proprietary and some shared with cognition. The argument for perceptual pluralism marshals a wide array of empirical evidence in favor of iconic (i.e., image-like, analog) representations in perception as well as discursive (i.e., language-like, digital) perceptual object representations
Evaluation of the exposure, dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study – Interim results Part 1: Experimental design, aerosol exposure, lung burdens and BAL
Abstract: This 90-day repeated-dose inhalation toxicology study of brake-dust (BD) (brakes manufactured with chrysotile) in rats provides a comprehensive understanding of the biokinetics and potential toxicology in the lung and pleura. Exposure was 6 h/d, 5d/wk., 13wks followed by lifetime observation (~20 % survival). Control groups included a particle control (TiO2), chrysotile, commercial crocidolite and amosite asbestos. Aerosol fiber distributions of the chrysotile, crocidolite and amosite were similar (fibers L > 20 μm/cm3 : chrysotile-Low/High 29/72; crocidolite 24; amosite 47 fibers/cm3 ; WHO-fibers/cm3 : chrysotile-Low/High 119/ 233; crocidolite 181; amosite 281 fibers/cm3 ). The number of particles/cm3 in the BD was similar to that in the chrysotile, crocidolite & amosite exposures (BD 470–715; chrysotile 495–614; crocidolite 415; amosite 417 particles/cm3 ). In the BD groups, few fibers L > 20 μm were observed in the lungs at the end of exposure and no fibers L > 20 μm at 90d post exposure. In the chrysotile groups, means of 204,000 and 290,000 fibers(L > 20 μm)/ lung were measured at 89d. By 180d, means of 1 and 3.9 fibers were counted on the filter corresponding to 14,000 and 55,000 fibers(L > 20 μm)/lung. In the crocidolite and amosite groups mean lung concentrations were 9,055,000 and 11,645,000 fibers (L > 20 μm)/lung at 89d. At 180d the means remained similar with 8,026,000 and 11,591,000 fibers (L > 20 μm)/lung representing 10–13% of the total lung fibers. BAL determined the total number of macrophages, lymphocytes, neutrophils, eosinophils, epithelial-cells and IL-1 beta, TNF-alpha and TGF-beta. At the moderate aerosol concentrations used in this study, neutrophil counts increased ~5 fold in the amphibole asbestos exposure groups. All other groups and parameters showed no important differences at these exposure concentrations. The exposure and lung burden results provide a sound basis for assessing the potential toxicity of the brake dust in comparison to the TiO2 particle control and the chrysotile, crocidolite and amosite asbestos control groups. The BAL results provide an initial indication of the differential response. Part 2 presents the presentation and discussion of the histopathological and confocal microscopy findings in this study through 90 days post exposure
Existence of superposition solutions for pulse propagation in nonlinear resonant media
Existence of self-similar, superposed pulse-train solutions of the nonlinear,
coupled Maxwell-Schr\"odinger equations, with the frequencies controlled by the
oscillator strengths of the transitions, is established. Some of these
excitations are specific to the resonant media, with energy levels in the
configurations of and and arise because of the interference
effects of cnoidal waves, as evidenced from some recently discovered identities
involving the Jacobian elliptic functions. Interestingly, these excitations
also admit a dual interpretation as single pulse-trains, with widely different
amplitudes, which can lead to substantially different field intensities and
population densities in different atomic levels.Comment: 11 Pages, 6 Figures, presentation changed and 3 figures adde
Optical Properties of Layered Superconductors near the Josephson Plasma Resonance
We study the optical properties of crystals with spatial dispersion and show
that the usual Fresnel approach becomes invalid near frequencies where the
group velocity of the wave packets inside the crystal vanishes. Near these
special frequencies the reflectivity depends on the atomic structure of the
crystal provided that disorder and dissipation are very low. This is
demonstrated explicitly by a detailed study of layered superconductors with
identical or two different alternating junctions in the frequency range near
the Josephson plasma resonance. Accounting for both inductive and charge
coupling of the intrinsic junctions, we show that multiple modes are excited
inside the crystal by the incident light, determine their relative amplitude by
the microscopic calculation of the additional boundary conditions and finally
obtain the reflectivity.
Spatial dispersion also provides a novel method to stop light pulses, which
has possible applications for quantum information processing and the artificial
creation of event horizons in a solid.Comment: 25 pages, 20 figures, submitted to Phys. Rev.
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