493 research outputs found
Geophysical investigation along parts of the Dent and Augill Faults
The areas covered in the present investigation lie near the towns of
Brough and Kirkby Stephen. They include parts of the Dent and Augill
Faults, which form the western margins of the Askrigg and Alston Blocks
respectively.
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The higher ground is open moorland used for sheep-grazing and is difficult
of access except to cross-country vehicles, but the lower ground is in
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agriculturai use , generally as pasture, and is well served by roads and tracks.
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The airborne electromagnetic (AEM) survey was restricted to the areas
of known mineral veins (Fig. 1) along the Dent and Augill faults. NO
geochemical exploration was undertaken because of widespread contamination
from the numerous mine dumps.
GEOLOGY
The northern part of the area shown in Fig. 1 was re-surveyed between
1958 and 1967 (Burgess and Holliday, in press) following the 19th-century
primary survey. The southern part has not been completely re-surveyed,
although parts of it were revised for the 1 inch to 1 mile scale geological
map (Kirkby Stephen sheet 40) published in 1972 and detailed mapping of
selected areas has formed part of the present investigations.
The area is mainly underlain by Carboniferous rocks (Fig. 2) and details
of the successions are given in Figs. 2, 5 and 6. Permo-Triassic deposits are
present to the west, j ust beyond the areas of detailed work (Fig. 2).
The oldest Carboniferous rocks exposed are the Orton Group, comprising
marine limestones with sandstones and shales. The lower part of the overlying
Alston Group consists of the massively bedded Great Scar Limestone, about 100 m
thick. The succeeding beds comprise alternating limestones, mudstones,
siltstones and sandstones deposited in a sequence of cyclothems. These are
internally very variable and any one cyclothem is rarely fully developed
Developing Courses in Languages for Specific Purposes
The goals of most foreign language (FL) instruction in higher education within the United States are built around three main components: (a) the acquisition of the knowledge of language skills for general communication use; (b) exposing learners to other cultures and ideas; and (c) fostering an appreciation of differences in cultures and ways of thinking. While each of these are certainly noble outcomes and likely meet the needs of the majority of university level FL learners, they remain quite broad in terms of what it is a learner will actually be able to do with the language once they have left the classroom. This is especially true for those of us faced with learners who have specific and sometimes immediate language needs that require more than generalized or dispositional knowledge alone. For these learners, Language for Specific Purposes courses provide an invaluable alternative or supplement to general language courses.The goals of most foreign language (FL) instruction in higher education within the United States are built around three main components: (a) the acquisition of the knowledge of language skills for general communication use; (b) exposing learners to other cultures and ideas; and (c) fostering an appreciation of differences in cultures and ways of thinking. While each of these are certainly noble outcomes and likely meet the needs of the majority of university level FL learners, they remain quite broad in terms of what it is a learner will actually be able to do with the language once they have left the classroom. This is especially true for those of us faced with learners who have specific and sometimes immediate language needs that require more than generalized or dispositional knowledge alone. For these learners, Language for Specific Purposes courses provide an invaluable alternative or supplement to general language courses
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The behavior, quantity, and location of undissolved gas in Tank 241-SY-101
Mitigation of episodic flammable gas releases from Hanford Waste Tank 241-SY-101 was accomplished in July 1993 with the installation of a mixer pump that prevents gas retention. But is has not been possible until recently to measure the effects of mixing on the waste or how much gas remains and where it is located. Direct measurements of the void fraction and rheology of the mixed waste by the void fraction instrument (VFI) and ball rheometer along with previous data provide estimates of the location, quantity, and behavior of undissolved gas in the tank. This report documents the compilation and integration of the information that enables this understanding
A statistical correlation of sunquakes based on their seismic and white-light emission
Several mechanisms have been proposed to explain the transient seismic emission, i.e. “sunquakes,” from some solar flares. Some theories associate high-energy electrons and/or white-light emission with sunquakes. High-energy charged particles and their subsequent heating of the photosphere and/or chromosphere could induce acoustic waves in the solar interior. We carried out a correlative study of solar flares with emission in hard X-rays, enhanced continuum emission at 6173 Å, and transient seismic emission. We selected those flares observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) with a considerable flux above 50 keV between 1 January 2010 and 26 June 2014. We then used data from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory to search for excess visible-continuum emission and new sunquakes not previously reported. We found a total of 18 sunquakes out of 75 flares investigated. All of the sunquakes were associated with an enhancement of the visible continuum during the flare. Finally, we calculated a coefficient of correlation for a set of dichotomic variables related to these observations. We found a strong correlation between two of the standard helioseismic detection techniques, and between sunquakes and visible-continuum enhancements. We discuss the phenomenological connectivity between these physical quantities and the observational difficulties of detecting seismic signals and excess continuum radiation
Statistical Models for Solar Flare Interval Distribution in Individual Active Regions
This article discusses statistical models for solar flare interval
distribution in individual active regions. We analyzed solar flare data in 55
active regions that are listed in the GOES soft X-ray flare catalog. We discuss
some problems with a conventional procedure to derive probability density
functions from any data set and propose a new procedure, which uses the maximum
likelihood method and Akaike Information Criterion (AIC) to objectively compare
some competing probability density functions. We found that lognormal and
inverse Gaussian models are more likely models than the exponential model for
solar flare interval distribution in individual active regions. The results
suggest that solar flares do not occur randomly in time; rather, solar flare
intervals appear to be regulated by solar flare mechanisms. We briefly mention
a probabilistic solar flare forecasting method as an application of a solar
flare interval distribution analysis.Comment: 15 pages, 2 figures, 3 tables, accepted for publication in Solar
Physic
Palaeoproterozoic magnesite: lithological and isotopic evidence for playa/sabkha environments
Magnesite forms a series of 1- to 15-m-thick beds within the approximate to2.0 Ga (Palaeoproterozoic) Tulomozerskaya Formation, NW Fennoscandian Shield, Russia. Drillcore material together with natural exposures reveal that the 680-m-thick formation is composed of a stromatolite-dolomite-'red bed' sequence formed in a complex combination of shallow-marine and non-marine, evaporitic environments. Dolomite-collapse breccia, stromatolitic and micritic dolostones and sparry allochemical dolostones are the principal rocks hosting the magnesite beds. All dolomite lithologies are marked by delta C-13 values from +7.1 parts per thousand to +11.6 parts per thousand (V-PDB) and delta O-18 ranging from 17.4 parts per thousand to 26.3 parts per thousand (V-SMOW). Magnesite occurs in different forms: finely laminated micritic; stromatolitic magnesite; and structureless micritic, crystalline and coarsely crystalline magnesite. All varieties exhibit anomalously high delta C-13 values ranging from +9.0 parts per thousand to +11.6 parts per thousand and delta O-18 values of 20.0-25.7 parts per thousand. Laminated and structureless micritic magnesite forms as a secondary phase replacing dolomite during early diagenesis, and replaced dolomite before the major phase of burial. Crystalline and coarsely crystalline magnesite replacing micritic magnesite formed late in the diagenetic/metamorphic history. Magnesite apparently precipitated from sea water-derived brine, diluted by meteoric fluids. Magnesitization was accomplished under evaporitic conditions (sabkha to playa lake environment) proposed to be similar to the Coorong or Lake Walyungup coastal playa magnesite. Magnesite and host dolostones formed in evaporative and partly restricted environments; consequently, extremely high delta C-13 values reflect a combined contribution from both global and local carbon reservoirs. A C- 13-rich global carbon reservoir (delta C-13 at around +5 parts per thousand) is related to the perturbation of the carbon cycle at 2.0 Ga, whereas the local enhancement in C-13 (up to +12 parts per thousand) is associated with evaporative and restricted environments with high bioproductivity
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Coherent control of electron spin qubits in silicon using a global field
Silicon spin qubits promise to leverage the extraordinary progress in silicon nanoelectronic device fabrication over the past half century to deliver large-scale quantum processors. Despite the scalability advantage of using silicon technology, realising a quantum computer with the millions of qubits required to run some of the most demanding quantum algorithms poses several outstanding challenges, including how to control many qubits simultaneously. Recently, compact 3D microwave dielectric resonators were proposed as a way to deliver the magnetic fields for spin qubit control across an entire quantum chip using only a single microwave source. Although spin resonance of individual electrons in the globally applied microwave field was demonstrated, the spins were controlled incoherently. Here we report coherent Rabi oscillations of single electron spin qubits in a planar SiMOS quantum dot device using a global magnetic field generated off-chip. The observation of coherent qubit control driven by a dielectric resonator establishes a credible pathway to achieving large-scale control in a spin-based quantum computer
Time-frequency scaling transformation of the phonocardiogram based of the matching pursuit method.
International audienceA time-frequency scaling transformation based on the matching pursuit (MP) method is developed for the phonocardiogram (PCG). The MP method decomposes a signal into a series of time-frequency atoms by using an iterative process. The modification of the time scale of the PCG can be performed without perceptible change in its spectral characteristics. It is also possible to modify the frequency scale without changing the temporal properties. The technique has been tested on 11 PCG's containing heart sounds and different murmurs. A scaling/inverse-scaling procedure was used for quantitative evaluation of the scaling performance. Both the spectrogram and a MP-based Wigner distribution were used for visual comparison in the time-frequency domain. The results showed that the technique is suitable and effective for the time-frequency scale transformation of both the transient property of the heart sounds and the more complex random property of the murmurs. It is also shown that the effectiveness of the method is strongly related to the optimization of the parameters used for the decomposition of the signals
Time-dependent Stochastic Modeling of Solar Active Region Energy
A time-dependent model for the energy of a flaring solar active region is
presented based on a stochastic jump-transition model (Wheatland and Glukhov
1998; Wheatland 2008; Wheatland 2009). The magnetic free energy of the model
active region varies in time due to a prescribed (deterministic) rate of energy
input and prescribed (random) flare jumps downwards in energy. The model has
been shown to reproduce observed flare statistics, for specific
time-independent choices for the energy input and flare transition rates.
However, many solar active regions exhibit time variation in flare
productivity, as exemplified by NOAA active region AR 11029 (Wheatland 2010).
In this case a time-dependent model is needed. Time variation is incorporated
for two cases: 1. a step change in the rates of flare jumps; and 2. a step
change in the rate of energy supply to the system. Analytic arguments are
presented describing the qualitative behavior of the system in the two cases.
In each case the system adjusts by shifting to a new stationary state over a
relaxation time which is estimated analytically. The new model retains
flare-like event statistics. In each case the frequency-energy distribution is
a power law for flare energies less than a time-dependent rollover set by the
largest energy the system is likely to attain at a given time. For Case 1, the
model exhibits a double exponential waiting-time distribution, corresponding to
flaring at a constant mean rate during two intervals (before and after the step
change), if the average energy of the system is large. For Case 2 the
waiting-time distribution is a simple exponential, again provided the average
energy of the system is large. Monte Carlo simulations of Case~1 are presented
which confirm the analytic estimates. The simulation results provide a
qualitative model for observed flare statistics in active region AR 11029.Comment: 25 pages, 9 figure
Immunohistochemical detection of macrophage migration inhibitory factor in fetal and adult bovine epididymis: Release by the apocrine secretion mode?
Originally defined as a lymphokine inhibiting the random migration of macrophages, the macrophage migration inhibitory factor (MIF) is an important mediator of the host response to infection. Beyond its function as a classical cytokine, MIF is currently portrayed as a multifunctional protein with growth-regulating properties present in organ systems beyond immune cells. In previous studies, we detected substantial amounts of MIF in the rat epididymis and epididymal spermatozoa, where it appears to play a role during post-testicular sperm maturation and the acquisition of fertilization ability. To explore its presence in other species not yet examined in this respect, we extended the range of studies to the bull. Using a polyclonal antibody raised against MIF purified from bovine eye lenses, we detected MIF in the epithelium of the adult bovine epididymis with the basal cells representing a prominently stained cell type. A distinct accumulation of MIF at the apical cell pole of the epithelial cells and in membranous vesicles localized in the lumen of the epididynnal duct was obvious. In the fetal bovine epididymis, we also detected MIF in the epithelium, whereas MIF accumulation was evident at the apical cell surface and in apical protrusions. By immuno-electron microscopy of the adult bovine epididymis, we localized MIF in apical protrusions of the epithelial cells and in luminal membrane-bound vesicles that were found in close proximity to sperm cells. Although the precise origin of the MIF-containing vesicles remains to be delineated, our morphological observations support the hypothesis that they become detached from the apical surface of the epididymal epithelial cells. Additionally, an association of MIF with the outer dense fibers of luminal spermatozoa was demonstrated. Data obtained in this study suggest MIF release by an apocrine secretion mode in the bovine epididymis. Furthermore, MIF localized in the basal cells of the epithelium and in the connective tissue could be responsible for regulating the migration of macrophages in order to avoid contact of immune cells with spermatozoa that carry a wide range of potent antigens. Copyright (c) 2006 S. Karger AG, Basel
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