1,331 research outputs found
Petrology, tectonic setting, and 40Ar/ 39Ar (hornblende) dating of the Late Ordovician - Early Silurian Belle Côte Road orthogneiss, western Cape Breton Highlands, Nova Scotia
The Belle Côte Road orthogneiss is a major component of the western Cape Breton Highlands, where it forms a belt approximately 60 km in length. Previous U-Pb dating has shown that the granodioritic to tonalitic protolith of the gneiss crystallized at 442 ± 3 Ma, providing a minimum age for the metavolcanic and metasedimentary units of the Aspy terrane intruded by the orthogneiss. The gneissic fabric in the orthogneiss is mainly conformable with the regional fabric, and generally trends north-south, except in the southern part of the unit where it is oriented east-west. Typical orthogneiss contains quartz, plagioclase, and biotite, with variable amounts of K-feldspar and muscovite and rarely epidote or garnet. A tonalitic variant contains amphibole. The orthogneiss is peraluminous, with A/CNK values of 1to 1.2. Petrochemical characteristics are consistent with syntectonic emplacement in the roots of a volcanic arc built on continental crust. 40Ar/39Ar dating was done on hornblende from three samples of orthogneiss and seven samples of amphibolite from xenoliths in the orthogneiss and an adjacent amphibolite unit. Eight of these samples yielded cooling ages ranging between 384 and 370 Ma. Two younger ages (ca. 363 and 353 Ma) may reflect localized effects of younger plutonism and/or shearing. The 40Ar/39Ar data combined with previous U-Pb data from titanite indicate that the orthogneiss and associated units experienced rapid cooling from ca. 600 to 400°C between ca. 386 Ma and 370 Ma, perhaps related to uplift associated with ongoing terrane amalgamation in Cape Breton Island.
RÉSUMÉ
Les orthogneiss de Route de Belle Côte est un composant important des hautes terres du Cap Breton occidental, où il forme une ceinture approximative de 60 kilomètres de longueur. Des mesures connues d'U-Pb a prouvé que le granodioritique au protolite tonalitique du gneiss a cristallisé au ± 442 3 Ma, fournissant un âge minimum pour les unités métavolcaniques et métasédimentaires du terrane d'Aspy imposé par les orthogneiss. Le tissu gneissique dans les orthogneiss est principalement conforme au tissu régional, et a une tendance généralement nord-sud excepté dans la partie sud de l'unité où la tendance est est-ouest. Les orthogneiss typiques contient le quartz, le plagioclase, et la biotite, avec des quantités variables de K-feldspath et de muscovite et rarement d'épidote ou de grenat. Une variante tonalitique contient l'amphibole. Les orthogneiss sont péralumineux. avec des valeurs A/CNK de 1 à 1.2. Les caractéristiques p&rochimiques sont conformées a là mise en place syntectonique dans les racines d'un arc volcanique construit sur la croute continentale. La datation d' 40Ar/39Ar à été faite sur la hornblende de trois échantillons d'orthogneiss et de sept échantillons d'amphibolite provenant de xénolites dans les orthogneiss et une unité adjacente d'amphibolite. Huit de ces échantillons ont rapporté des âges de refroidissement s'étendant entre 384 et 370 de Ma. Deux àges plus jeunes (ca. 363 et 353 Ma) peuvent refléter des effets localises des plus jeunes plutonismes et/ou cisaillement. Les données 40Ar/39Ar combing avec des données précédentes d'U-Pb de titanite indiquent que les orthogneiss et les unites associées ont éprouve' le refroidissement rapide ca de 600 a 400°C entre ca. 386 Ma et 370 Ma, peut-ètre assocté au soulèvement en plus d'amalgamation continue de terrane sur Tile du Cap Breton.
[Traduit par la rédaction
DO LATITUDE, ELEVATION, TEMPERATURE, AND PRECIPITATION INFLUENCE BODY AND CLUTCH SIZES OF FEMALE COMMON FIVE-LINED SKINKS, PLESTIODON FASCIATUS (LINNAEUS, 1758)?
Common Five-lined Skinks (Plestiodon fasciatus) have an extensive distribution that includes much of eastern North America. We examined 490 female specimens (274 with putative clutch sizes) from throughout the range to see if latitude, elevation, mean annual temperature, and/or mean annual precipitation affected body or clutch sizes. We predicted that larger females would produce larger clutches, latitude and elevation would negatively affect both body and clutch sizes, and that temperature and precipitation would exert a positive effect. Our results did not consistently support those predictions. Body size was positively associated with latitude, negatively associated with temperature, and not associated with elevation or precipitation. Clutch size was not related to female body size, but in most instances was positively associated with temperature and precipitation but negatively associated with elevation and latitude. Effectively K-selected in the North and r-selected in the South, body and clutch sizes in this species appear to be responding to different select
Classification of phase transitions and ensemble inequivalence, in systems with long range interactions
Systems with long range interactions in general are not additive, which can
lead to an inequivalence of the microcanonical and canonical ensembles. The
microcanonical ensemble may show richer behavior than the canonical one,
including negative specific heats and other non-common behaviors. We propose a
classification of microcanonical phase transitions, of their link to canonical
ones, and of the possible situations of ensemble inequivalence. We discuss
previously observed phase transitions and inequivalence in self-gravitating,
two-dimensional fluid dynamics and non-neutral plasmas. We note a number of
generic situations that have not yet been observed in such systems.Comment: 42 pages, 11 figures. Accepted in Journal of Statistical Physics.
Final versio
Land cover and vegetation data from an ecological survey of `key habitat' landscapes in England, 1992-1993
Since 1978, a series of national surveys (Countryside Survey, CS) have been carried out by the Centre for Ecology and Hydrology (CEH) (formerly the Institute of Terrestrial Ecology, ITE) to gather data on the natural environment in Great Britain (GB). As the sampling framework for these surveys is not optimised to yield data on rarer or more localised habitats, a survey was commissioned by the then Department of the Environment (DOE, now the Department for Environment, Food and Rural Affairs, DEFRA) in the 1990s to carry out additional survey work in English landscapes which contained semi-natural habitats that were perceived to be under threat, or which represented areas of concern to the ministry. The landscapes were lowland heath, chalk and limestone (calcareous) grasslands, coasts and uplands. The information recorded allowed an assessment of the extent and quality of a range of habitats defined during the project, which can now be translated into standard UK broad and priority habitat classes. The survey, known as the "Key Habitat Survey", followed a design which was a series of gridded, stratified, randomly selected 1 km squares taken as representative of each of the four landscape types in England, determined from statistical land classification and geological data ("spatial masks"). The definitions of the landscapes are given in the descriptions of the spatial masks, along with definitions of the surveyed habitats. A total of 213 of the 1 km2 square sample sites were surveyed in the summers of 1992 and 1993, with information being collected on vegetation species, land cover, landscape features and land use, applying standardised repeatable methods. The database contributes additional information and value to the long-term monitoring data gathered by the Countryside Survey and provides a valuable baseline against which future ecological changes may be compared, offering the potential for a repeat survey. The data were analysed and described in a series of contract reports and are summarised in the present paper, showing for example that valuable habitats were restricted in all landscapes, with the majority located within protected areas of countryside according to different UK designations. The dataset provides major potential for analyses, beyond those already published, for example in relation to climate change, agri-environment policies and land management. Precise locations of the plots are restricted, largely for reasons of landowner confidentiality. However, the representative nature of the dataset makes it highly valuable for evaluating the status of ecological elements within the associated landscapes surveyed. Both land cover data and vegetation plot data were collected during the surveys in 1992 and 1993 and are available via the following DOI: https://doi.org/10.5285/7aefe6aa-0760-4b6d-9473-fad8b960abd4. The spatial masks are also available from https://doi.org/10.5285/dc583be3-3649-4df6-b67e-b0f40b4ec895
Being Motivated to Protect : The Influence of Sexual Communal Motivations on Sexual Risk Taking
College-aged students are a high-risk population for unplanned pregnancy with 40% of women between the ages of 18-20 experiencing an unplanned pregnancy. This can cause physical, mental, and emotional stress resulting in withdrawal from college for the student. Communal motivation (being oriented towards other’s needs) positively predicts condom use. WISE interventions, a simple yet impactful type of interventions targeted towards addressing a problem, have been shown to be successful. Participants completed a sexual risk behavior measure, sexual risk-taking measure and communal motivations (CM) measure following a sexual health video, and reflection activity were participants either applied the sexual health information to their relationship (experimental) or reflected on the sexual health material presented (control). CM was positively correlated with number of sexual partners in the past 3 months, r(262) = .162,
Of CP and other Gauge Symmetries in String Theory
We argue that \CP is a gauge symmetry in string theory. As a consequence, \CP
cannot be explicitly broken either perturbatively or non-pertubatively; there
can be no non-perturbative \CP-violating parameters. String theory is thus an
example of a theory where all angles arise due to spontaneous \CP
violation, and are in principle calculable.Comment: 8 page
Identification of a Likely Radio Counterpart of the Rapid Burster
We have identified a likely radio counterpart to the low-mass X-ray binary
MXB 1730-335 (the Rapid Burster). The counterpart has shown 8.4 GHz radio
on/off behavior correlated with the X-ray on/off behavior as observed by the
RXTE/ASM during six VLA observations. The probability of an unrelated, randomly
varying background source duplicating this behavior is 1-3% depending on the
correlation time scale. The location of the radio source is RA 17h 33m 24.61s;
Dec -33d 23' 19.8" (J2000), +/- 0.1". We do not detect 8.4 GHz radio emission
coincident with type II (accretion-driven) X-ray bursts. The ratio of radio to
X-ray emission during such bursts is constrained to be below the ratio observed
during X-ray persistent emission at the 2.9-sigma level. Synchrotron bubble
models of the radio emission can provide a reasonable fit to the full data set,
collected over several outbursts, assuming that the radio evolution is the same
from outburst to outburst, but given the physical constraints the emission is
more likely to be due to ~hour-long radio flares such as have been observed
from the X-ray binary GRS 1915+105.Comment: 28 pages, 4 figures; accepted for publication in ApJ (no changes
HIV-Associated Mycobacterium tuberculosis Bloodstream Infection Is Underdiagnosed by Single Blood Culture
ABSTRACT
We assessed the additional diagnostic yield for
Mycobacterium tuberculosis
bloodstream infection (BSI) by doing more than one tuberculosis (TB) blood culture from HIV-infected inpatients. In a retrospective analysis of two cohorts based in Cape Town, South Africa, 72/99 (73%) patients with
M. tuberculosis
BSI were identified by the first of two blood cultures during the same admission, with 27/99 (27%; 95% confidence interval [CI], 18 to 36%) testing negative on the first culture but positive on the second. In a prospective evaluation of up to 6 blood cultures over 24 h, 9 of 14 (65%) patients with
M. tuberculosis
BSI had
M. tuberculosis
grow on their first blood culture; 3 more patients (21%) were identified by a second independent blood culture at the same time point, and the remaining 2 were diagnosed only on the 4th and 6th blood cultures. Additional blood cultures increase the yield for
M. tuberculosis
BSI, similar to what is reported for nonmycobacterial BSI.
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Local Ecology and Multiple Mating in a Natural Population of Drosophila melanogaster
The measurement of fitness components in natural populations is among the most important problems of population genetics. Much effort has been devoted to the measurement of one aspect of the reproductive component of fitness, the storage and use of sperm by females
A sensitivity study of parameters used in shrinkage and creep prediction models
Over the last 15 years, there have been numerous models put forward for the prediction of the time-dependent behaviour of concrete and consequently concrete structures. The development of these models from a number of different sources has meant that the engineer now has a choice to make when undertaking creep and shrinkage prediction and it is difficult to know which is best suited for this purpose. Some are considerably more complex than others requiring greater amounts of input focusing on material data, concrete properties, environmental conditions, specimen geometry and loading conditions. The study reported here focuses on the sensitivity to change, in both the short term and over time, of the individual parameters that comprise the input and whether one model is more appropriate in any given situation. It has been found that for each model certain parameters are more sensitive than others. It is suggested that for any given model, the parameters that do not reflect the expected behaviour when changed counterbalance each other, cancelling out any errors. This further suggests that when deciding on which model to use when predicting shrinkage and creep strains it is prudent to look at the specific conditions that prevail, assess the relevant input parameters for which data are available, assess the sensitivity level of each of these parameters and then make a decision as to the most appropriate model to use
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