364 research outputs found
Environmental control of conodont distribution in the Shawnee Group (Upper Pennsylvanian) of eastern Kansas
124 p., 16 pl., 18 fig.http://paleo.ku.edu/contributions.htm
The La Coulée Formation, a new post-Acadian continental clastic unit bearing groundwater calcretes, Gaspé Peninsula, Quebec
A 1 km2 erosional remnant of the La Coulée Formation, a previously unrecognized stratigraphic unit, has been studied in the Percé area of the Gaspé Peninsula. It unconformably overlies folded Cambrian to Devonian rocks and is unconformably overlain by the mid-Carboniferous Bonaventure Formation. The erosional remnant includes the lowest 60 m of this newly identified formation of unknown thickness. Original sedimentary fades are limited to 50 m of breccia debris flows passing stratigraphically upward into 10m of conglomeratic debris flows. Groundwater calcrete formation has partially or completely transformed the lowest 30 m of the sequence. The depositional environment is interpreted as being related to a proximal continental alluvial fan. The nearby presence of a saline body of water is inferred to account for thick and massive groundwater calcrete formation and water-saturated debris flows in a relatively arid climatic context Most of the formation was eroded prior to deposition of the Bonaventure Formation. However, the basal groundwater calcretes were more widely preserved. They underlie the Bonaventure Formation in most of the Percé area and in the Saint-Elzéar area, close to a hundred kilometres to the southwest. Post-sedimentary faulting has affected both the La Coulée and Bonaventure formations.
RÉSUMÉ
La Formation de La Coulée, une unite stratigraphique nouvellement répertoriée, a été éudiée a I'intérieur d'une masse résiduelle de 1 km2 dans la région de Percé en Gaspésie. La séquence recouvre en discordance des roches plissees du Dévonien Inférieur et elle est recouverte en discordance par la Formation de Bonaventure qui est attribuée au Carbonifere moyen. La masse résiduelle inclue les 60 premiers mètres de cette formation nouvellement identifiée et d'une épaisseur inconnue. Les fades sédimentaires originels sont limités à cinquante mètres de coulees de débris bréchiques, passant à une dizaine de mètres de coulées de débris conglomératiques. La formation d'une calcrete phréatique affecte les premiers 30 mètres de la séquence, lesquels sont en partie ou complètement transformés. L'environnement sédimentaire est interprété comme étant lié à un còne de déjection continental dans sa partie proximale, mais la présence non-lointaine d'un plan d'eau salde est suggerée pour expliquer la formation de calcretes phréatiques épaisses et massives, ainsi que la saturation en eau des coulées de débris dans un contexte climatique relativement aride. La formation a presqu'entierement été érodée avant que ne survienne la sédimentation de la Formation de Bonaventure. Toutefois, la base de calcrete a été plus largement préservée, ce qui fait qu'on la retrouve sous la Formation de Bonaventure preque partout dans la region de Percé ainsi que dans la région de Saint-Elzéar, a presqu'une centaine de kilomètres au sud-ouest. Des failles post-sédimentaires ont affecté à la fois la Formation de La Coulée et la Formation de Bonaventure
Dentin-like versus Rigid Endodontic Post: Eleven-year Randomized Controlled Pilot Trial on No-wall to Two-wall Defects
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Design studies for ITER x-ray diagnostics
Concepts for adapting conventional tokamak x-ray diagnostics to the harsh radiation environment of ITER include use of grazing-incidence (GI) x-ray mirrors or man-made Bragg multilayer (ML) elements to remove the x-ray beam from the neutron beam, or use of bundles of glass-capillary x-ray ``light pipes`` embedded in radiation shields to reduce the neutron/gamma-ray fluxes onto the detectors while maintaining usable x-ray throughput. The x-ray optical element with the broadest bandwidth and highest throughput, the GI mirror, can provide adequate lateral deflection (10 cm for a deflected-path length of 8 m) at x-ray energies up to 12, 22, or 30 keV for one, two, or three deflections, respectively. This element can be used with the broad band, high intensity x-ray imaging system (XIS), the pulseheight analysis (PHA) survey spectrometer, or the high resolution Johann x-ray crystal spectrometer (XCS), which is used for ion-temperature measurement. The ML mirrors can isolate the detector from the neutron beam with a single deflection for energies up to 50 keV, but have much narrower bandwidth and lower x-ray power throughput than do the GI mirrors; they are unsuitable for use with the XIS or PHA, but they could be used with the XCS; in particular, these deflectors could be used between ITER and the biological shield to avoid direct plasma neutron streaming through the biological shield. Graded-d ML mirrors have good reflectivity from 20 to 70 keV, but still at grazing angles (<3 mrad). The efficiency at 70 keV for double reflection (10 percent), as required for adequate separation of the x-ray and neutron beams, is high enough for PHA requirements, but not for the XIS. Further optimization may be possible
Pseudomonas aeruginosa pilin activates the inflammasome
IL-1 beta is produced from inactive pro-IL-1 beta by activation of caspase-1 brought about by a multi-subunit protein platform called the inflammasome. Many bacteria can trigger inflammasome activity through flagellin activation of the host protein NLRC4. However, strains of the common human pathogen Pseudomonas aeruginosa lacking flagellin can still activate the inflammasome. We set out to identify what non-flagellin components could produce this activation. Using mass spectroscopy, we identified an inflammasome-activating factor from P. aeruginosa as pilin, the major component of the type IV bacterial pilus. Purified pilin introduced into mouse macrophages by liposomal delivery activated caspase-1 and led to secretion of mature IL-1 beta, as did recombinant pilin purified from Escherichia coli. This was dependent on caspase-1 but not on the host inflammasome proteins NLRC4, NLRP3 or ASC. Mutants of P. aeruginosa strain PA103 lacking pilin did not activate the inflammasome following infection of macrophages with live bacteria. Type III secretion remained intact in the absence of pili, showing this was not due to a lack of effector delivery. Our observations show pilin is a novel activator of the inflammasome in addition to flagellin and the recently described PrgJ protein family, the basal body rod component of the type III apparatu
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Measurements of the intercombination and forbidden lines from helium-like ions in Tokamaks and Electron Beam Ion Traps
The paper reviews the results from tokamak experiments for the line ratios x/w, y/w, and z/w from helium-like ions with Z in the range from 14 to 28. With exception of the DITE experiments, where these line ratios were found to be in agreement with theoretical predictions, all other tokamak experiments yielded values that were significantly larger than predicted. The reasons for these discrepancies are not yet understood. It is possible that radial profile effects were not properly taken into account in the majority of the tokamak experiments. The paper also gives a short historical review of the X-ray diagnostic developments and also presents very recent data from a new type of X-ray imaging crystal spectrometer, which records spatially resolved spectra with a spatial resolution of about 1 cm in the plasma. These new data can be Abel inverted, so that it will be possible to determine line ratios at each radial position in the plasma. Effects of radial profiles, which may have affected the chord-integrated measurements of the past, will thus be eliminated in the future
A new fireworm (Amphinomidae) from the Cretaceous of Lebanon identified from three-dimensionally preserved myoanatomy
© 2015 Parry et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The attached file is the published version of the article
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Dielectronic satellite spectrum of helium-like iron (Fe XXV)
Dielectronic satellite spectra of Fe XXV near 1.8500 A have been observed from PLT (Princeton Large Torus) tokamak plasma discharges for electron temperatures in the range from 1.5 to 3 keV and an electron density of 2 x 10/sup 13/ cm/sup -3/. The electron temperature was independently determined from the electron cyclotron radiation emitted by the plasma. The quality of the spectra allows a detailed comparison with theoretical prediction, which is of importance in view of diagnostic applications
A study of the breakdown of the quasi-static approximation at high densities and its effect on the helium-like K ALPHA complex of nickel, iron, and calcium
The General Spectral Modeling (GSM) code employs the quasi-static
approximation, a standard, low-density methodology that assumes the ionization
balance is separable from a determination of the excited-state populations that
give rise to the spectra. GSM also allows for some states to be treated only as
contributions to effective rates. While these two approximations are known to
be valid at low densities, this work investigates using such methods to model
high-density, non-LTE emission spectra and determines at what point the
approximations break down by comparing to spectra produced by the LANL code
ATOMIC which makes no such approximations. As both approximations are used by
other astrophysical and low-density modeling codes, the results should be of
broad interest. He-like K emission spectra are presented for Ni, Fe,
and Ca, in order to gauge the effect of both approximations employed in GSM.
This work confirms that at and above the temperature of maximum abundance of
the He-like ionization stage, the range of validity for both approximations is
sufficient for modeling the low- and moderate-density regimes one typically
finds in astrophysical and magnetically confined fusion plasmas. However, a
breakdown does occur for high densities; we obtain quantitative limits that are
significantly higher than previous works. This work demonstrates that, while
the range of validity for both approximations is sufficient to predict the
density-dependent quenching of the z line, the approximations break down at
higher densities. Thus these approximations should be used with greater care
when modeling high-density plasmas such as those found in inertial confinement
fusion and electromagnetic pinch devices.Comment: Accepted by Physical Review A (http://pra.aps.org/). 11 pages + LANL
cover, 5 figures. Will update citation information as it becomes available.
Abbreviated abstract is listed her
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Tokamak x ray diagnostic instrumentation
Three classes of x-ray diagnostic instruments enable measurement of a variety of tokamak physics parameters from different features of the x-ray emission spectrum. (1) The soft x-ray (1 to 50 keV) pulse-height-analysis (PHA) diagnostic measures impurity concentrations from characteristic line intensities and the continuum enhancement, and measures the electron temperature from the continuum slope. (2) The Bragg x-ray crystal spectrometer (XCS) measures the ion temperature and neutral-beam-induced toroidal rotation velocity from the Doppler broadening and wavelength shift, respectively, of spectral lines of medium-Z impurity ions. Impurity charge state distributions, precise wavelengths, and inner-shell excitation and recombination rates can also be studied. X rays are diffracted and focused by a bent crystal onto a position-sensitive detector. The spectral resolving power E/..delta..E is greater than 10/sup 4/ and time resolution is 10 ms. (3) The x-ray imaging system (XIS) measures the spatial structure of rapid fluctuations (0.1 to 100 kHZ) providing information on MHD phenomena, impurity transport rates, toroidal rotation velocity, plasma position, and the electron temperature profile. It uses an array of silicon surface-barrier diodes which view different chords of the plasma through a common slot aperture and operate in current (as opposed to counting) mode. The effectiveness of shields to protect detectors from fusion-neutron radiation effects has been studied both theoretically and experimentally
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