bluuebunny/crossref_metadata_2025 huggingface dataset:
The age of Calluna stands moderates post‐fire regeneration rate and trends in northern Calluna heathlands
Authors: Velle Liv G. , Nilsen Liv S. , Vandvik Vigdis
Published: July 2011

Questions: Does stand age influence the direction and rate of post‐fire successional dynamics in coastal Calluna heaths and can old degraded heath vegetation be restored through reintroduction of fire?

Location: Coastal heaths in the Tarva archipelago, central Norway.

Methods: We investigated revegetation dynamics after experimental fires set in young (8 years since last fire) and old (>50 years since last fire) grazed heath stands. A repeated measures design was used, with floristic data recorded in permanent plots in the post‐fire successions (n=12) over a 7‐year period. The data were analysed using multivariate ordination techniques (PCA, RDA and PRC) and mixed effects models.

Results: The age of Calluna stands strongly influenced post‐fire succession, different trends due to age explained 10.4% of variation in floristic data. Young heath showed faster succession towards pre‐fire community composition than old heath, and this could partially be explained by succession‐related factors: young heath had lower cover of mosses and lichens in the pre‐burned vegetation, and lower cover of litter early in succession. Young heath had a less pronounced overall community response to fire than old heath. Vegetative regeneration of C. vulgaris was absent in both old and young heath, but Calluna still re‐established as the dominant species within 5–7 years in both young and old stands. Regeneration dynamics were also affected by habitat conditions, different trends due to habitat explained 6% of variation.

Conclusions: Our study demonstrates that old stands do develop characteristic heathland vegetation and structure after fire, and while potential invasives into the system such as trees and rhizomatous species are present, they do not impair Calluna regeneration or vegetation development towards the target heathland community composition and structure. Further, as our young stands are only in their second fire rotation after restoration, we suggest that characteristic dynamics of managed heathlands can re‐establish relatively rapidly, even in severely degenerated sites (>50 years since last fire). Site‐specific factors also need to be considered. We conclude that there is restoration potential in old heaths, despite slow dynamics in the first rotation.
Aristotle’s Early and Late Ontologies
Authors: Studtmann Paul
Published: July 2011

There is a very deep tension that exists at the heart of Aristotle’s metaphysical system in virtue of the fact that his works seem to contain two distinct and not obviously commensurate ontologies: an early ontology that Aristotle outlines in the Categories and a later ontology that he develops in his physical–metaphysical treatises. In this paper I briefly describe the two ontologies, discuss the sources of conflict and outline different scholarly speculations about the relationship between the two.
Hegel, Psychoanalysis and Intersubjectivity
Authors: Macdonald Molly
Published: July 2011

This article aims to locate the connections between Hegel’s philosophy and psychoanalytic theory, with a particular focus on the model of intersubjectivity, as drawn from his Phenomenology of Spirit. The roots of the encounter between the philosophy of Hegel and psychoanalytic theory can be traced back to Jacques Lacan and the less well‐considered figure of Jean Hyppolite. Lacan, as a psychoanalyst, used Hegel’s thought in his own theory, as is well known, while Hyppolite was arguably one of the first to write from a philosophical angle about the links between the two seemingly opposed systems of thinking. I will give a broad overview of the use of Hegelian philosophy in psychoanalytic theory from the Hyppolite–Lacan relationship through to contemporary thinkers in the fields of philosophy and psychoanalysis. Although recently the figure of Slavoj Žižek has popularised the Hegel‐psychoanalysis connection, there remains much more to be explored in this branch of Hegel studies that widens the scope beyond the Lacanian‐Marxist version he employs. This article will survey existing literature (in the English language) and thus illuminate the key texts in the history of Hegel’s impact on psychoanalytic theory and the concept of intersubjectivity and gesture towards the future potential of this line of inquiry.
Associative Political Obligations: Their Potential
Authors: van der Vossen Bas
Published: July 2011

This article adopts the framework set out in ‘Associative Political Obligations’ to ask two further questions about the theory of associative political obligation. (i) Which of the different interpretations of the theory of associative political obligation is most plausible? And (ii) what would be the implications of such a view? It is argued that (i) the most attractive version of the argument is one according to which such obligations obtain only in morally acceptable communities, and only between what may be called ‘thick’ members. And (ii) that such a theory should give up on at least some of the conclusions that associativist theorists have tried to defend, such as that associative political obligations can establish the legitimacy of states. However, it is also suggested that this should not be considered a regrettable retreat.
Associative Political Obligations
Authors: van der Vossen Bas
Published: July 2011

This article aims to provide some insight into the nature and content of the theory of associative political obligation. It does this by first locating the view in the wider debate on political obligation, analyzing the view in terms of four central elements that are shared by many of its versions, and then discussing important criticisms that have been made of each of these, as well as some rejoinders by defenders of the theory.
Gastroprotective activity of methanol extract and marrubiin obtained from leaves of Marrubium vulgare L. (Lamiaceae)
Authors: Paula de Oliveira Ana , Santin José Roberto , Lemos Marivane , Klein Júnior Luiz Carlos , Couto Angélica Garcia , Meyre da Silva Bittencourt Christiane , Filho Valdir Cechinel , Faloni de Andrade Sérgio
Published: July 2011

Objectives

The purpose of this study was to assess the gastroprotective properties of the methanol extract and the diterpene marrubiin obtained from the leaves of M. vulgare.

Methods

Assays were performed using different protocols in mice. Studies focusing on mechanisms of gastroprotection were also undertaken.

Key findings

In the model of ethanol-induced ulcers, we observed a significant reduction in all the parameters analysed; the curative ratios obtained were 49.31 ± 0.57, 74.31 ± 0.91 and 79.86 ± 0.59 for the groups treated with 50 and 100 mg/kg of extract of M. vulgare and omeprazole (30 mg/kg), respectively. For indomethacin-induced ulcers, the percentages of ulcer inhibition were 50.32 ± 5.60, 66.24 ± 4.30, 82.17 ± 04.09 and 67.52 ± 4.38, for the groups treated with 25, 50 and 100 mg/kg M. vulgare and positive control (cimetidine), respectively. In both models, the marrubiin (25 mg/kg) produced a significant reduction in all the parameters when compared with the control group (P < 0.01). There was also a significant increase in pH and mucus production in the groups treated with M. vulgare extract and marubiin. The results also demonstrated that the gastroprotection induced by the extract and marubiin is related to the activity of nitric oxide and endogenous sulfhydryls, which are important gastroprotective factors.

Conclusions

The results of this study show that the extract of M. vulgare and marrubiin displays antiulcer activity and that this effect can be partly attributed to the isolated diterpene.
Free Convection Boundary Layer Flow Past a Horizontal Flat Plate Embedded in a Porous Medium Filled With a Nanofluid
Authors: Khan W. A. , Pop I.
Published: July 2011

A similarity solution is presented for the steady free convection boundary layer flow past a horizontal flat plate embedded in a porous medium filled with nanofluids. The model used for the nanofluid is the one which incorporates the effects of Brownian motion and thermophoresis. For the porous medium the Darcy-Boussinesq model is employed. This solution depends on a Lewis number Le, a buoyancy-ratio parameter Nr, a Brownian motion parameter Nb, and a thermophoresis parameter Nt. The effects of these parameters on the velocity, temperature and nanoparticle fraction profiles are discussed. The dependency of the local Nusselt and Sherwood numbers on these four parameters is also investigated.
Toward a Better Understanding of Model Validation Metrics
Authors: Liu Yu , Chen Wei , Arendt Paul , Huang Hong-Zhong
Published: July 2011

Model validation metrics have been developed to provide a quantitative measure that characterizes the agreement between predictions and observations. In engineering design, the metrics become useful for model selection when alternative models are being considered. Additionally, the predictive capability of a computational model needs to be assessed before it is used in engineering analysis and design. Due to the various sources of uncertainties in both computer simulations and physical experiments, model validation must be conducted based on stochastic characteristics. Currently there is no unified validation metric that is widely accepted. In this paper, we present a classification of validation metrics based on their key characteristics along with a discussion of the desired features. Focusing on stochastic validation with the consideration of uncertainty in both predictions and physical experiments, four main types of metrics, namely classical hypothesis testing, Bayes factor, frequentist’s metric, and area metric, are examined to provide a better understanding of the pros and cons of each. Using mathematical examples, a set of numerical studies are designed to answer various research questions and study how sensitive these metrics are with respect to the experimental data size, the uncertainty from measurement error, and the uncertainty in unknown model parameters. The insight gained from this work provides useful guidelines for choosing the appropriate validation metric in engineering applications.
An Investigation of Root Stresses of Hypoid Gears with Misalignments
Authors: Hotait M. A. , Kahraman A. , Nishino T.
Published: July 2011

In this study, the impact of misalignments on root stresses of hypoid gear sets is investigated experimentally and theoretically. An experimental set-up designed to allow operation of a hypoid gear pair under loaded quasi-static conditions with various types of tightly controlled misalignments is introduced. These misalignments include the position errors (V and H) of the pinion along the vertical and horizontal directions, the position error (G) of the gear along its axis, and the angle error (γ) between the two gear axes. For example, face-hobbed hypoid gear pair from an automotive axle application is instrumented via a set of strain gauges positioned at the roots along the faces of multiple teeth to measure root strains within a range of input torque. These root strain measurements at different V, H, G, and γ values are presented. A computational model is also proposed to predict the root stresses of face-milled and face-hobbed hypoid gear pairs under various loading and misalignment conditions. The model employs an automated finite elements mesh generator based on a predefined template for a general and computationally efficient treatment of the problem. Model predictions are compared to measurements at the end to assess the accuracy of the model and describe the measured sensitivities.
Numerical Simulation of Start-Up Jets in a Mixing Chamber
Authors: Lian Chenzhou , Voytovych Dmytro M. , Xia Guoping , Merkle Charles L.
Published: July 2011

Numerical simulations of the transient flow of helium injected into an established background flow of nitrogen were carried out to identify the dominant features of the transient mixing process between these two dissimilar gases. The geometry of interest is composed of two helium slots on either side of a central nitrogen channel feeding into a rectangular mixing chamber that was experimentally designed to give “two-dimensional” flow. Simulations were accomplished on both two- and three-dimensional grids. The 3D solutions employ an unsteady DES approach, while the 2D results are based upon a reduced dimension, “DES-like” method. Results are compared with quantitative experimental measurements of species distributions both in terms of contour plots and local point measurements. The 2D solutions give a reasonable qualitative picture of the transient mixing process in the center of the chamber while also providing quantitative estimates of representative characteristic times for guiding the 3D calculations. The 3D solutions give a reasonable approximation to span-wise variations observed in the experiment.
Effect of sputtering on ferromagnet-oxide-silicon spin injection contacts
Authors: Gundapaneni Suresh , Ganguly Swaroop , Van Roy Willem , Kaushal Sanjeev , Sugishima Kenji
Published: July 2011

The authors have fabricated metal-oxide-semiconductor (MOS) contacts on silicon for spin injection and detection and characterized them by internal photoemission and capacitance-voltage (C-V) measurements with the aim of extracting the metal- semiconductor effective work-function mismatch that determines the magnetoresistance between such contacts. The authors show that sputter deposition of these contacts induces high levels of negative charge in the oxide localized close to the metal-oxide interface. This is seen to affect the electrostatics of the MOS contact and could thereby impact its contact resistance, and in turn, the magnetoresistance that one can obtain.
Comparison of DC performance of Pt/Ti/Au- and Ni/Au-gated AlGaN/GaN high electron mobility transistors
Authors: Liu Lu , Lo Chien-Fong , Kang Tsung-Sheng , Ren Fan , Pearton S. J. , Kravchenko I. I. , Laboutin O. , Cao Yu , Johnson Wayne J.
Published: July 2011

We have demonstrated significant improvements of AlGaN/GaN high electron mobility transistors (HEMTs) dc performance by employing Pt/Ti/Au instead of the conventional Ni/Au gate metallization. During off-state bias stressing, the typical critical voltage for HEMTs with Ni/Au gate metallization was ∼−45 to −65 V. By sharp contrast, no critical voltage was observed for HEMTs with Pt/Ti/Au gate metallization, even up to −100 V, which was the instrumental limitation in this experiment. After the off-state stressing, the drain current of Ni/Au gated-HEMTs decreased by ∼15%. For the Pt-gate HEMTs, no degradation of the drain current occurred and there were minimal changes in the Schottky gate characteristics for both forward and reverse bias conditions. The HEMTs with Pt/Ti/Au metallization showed an excellent drain on/off current ratio of 1.56×108. The on/off drain current ratio of Ni-gated HEMTs was dependent on the drain bias voltage and ranged from 1.16×107 at VDS=5 V and 6.29×105 VDS=40 V due to the larger gate leakage current at higher drain bias voltage.
CRASY: Mass- or Electron-Correlated Rotational Alignment Spectroscopy
Authors: Schröter Christian , Kosma Kyriaki , Schultz Thomas
Published: July 2011

A technique merging rotational spectroscopy with mass spectrometry facilitates analysis of a complex isotopic mixture.
A Highly Conserved Neutralizing Epitope on Group 2 Influenza A Viruses
Authors: Ekiert Damian C. , Friesen Robert H. E. , Bhabha Gira , Kwaks Ted , Jongeneelen Mandy , Yu Wenli , Ophorst Carla , Cox Freek , Korse Hans J.W.M. , Brandenburg Boerries , Vogels Ronald , Brakenhoff Just P.J. , Kompier Ronald , Koldijk Martin H. , Cornelissen Lisette A.H.M. , Poon Leo L. M. , Peiris Malik , Koudstaal Wouter , Wilson Ian A. , Goudsmit Jaap
Published: July 2011

An antibody against a conserved epitope broadly neutralizes group 2 influenza viruses.
Herschel Detects a Massive Dust Reservoir in Supernova 1987A
Authors: Matsuura M. , Dwek E. , Meixner M. , Otsuka M. , Babler B. , Barlow M. J. , Roman-Duval J. , Engelbracht C. , Sandstrom K. , Lakićević M. , van Loon J. Th. , Sonneborn G. , Clayton G. C. , Long K. S. , Lundqvist P. , Nozawa T. , Gordon K. D. , Hony S. , Panuzzo P. , Okumura K. , Misselt K. A. , Montiel E. , Sauvage M.
Published: July 2011

The large amount of dust produced by this supernova may help explain the dust observed in young galaxies.
Transvenous embolization of a pediatric pial arteriovenous fistula
Authors: Cooke Daniel , Tatum James , Farid Hamed , Dowd Christopher , Higashida Randall , Halbach Van
Published: July 2011

Pial arteriovenous fistulas (AVFs) are a rare, although clinically significant, vascular anomaly affecting the pediatric population. There are few retrospective case series describing their epidemiological, clinical and radiographic characteristics as well as technical elements of treatment. Combined transarterial and transvenous embolization of a 12 month old female with a multi-hole pial AVF is described. The patient underwent treatment in a staged fashion and without neurological complication.
Is youth smoking responsive to cigarette prices? Evidence from low- and middle-income countries
Authors: Kostova Deliana , Ross Hana , Blecher Evan , Markowitz Sara
Published: July 2011

Objective

To estimate the price elasticity of cigarette demand among youth in low- and middle-income countries (LMIC).

Data

The Global Youth Tobacco Survey was used to obtain data on the smoking behaviour of 315 353 adolescents from 17 LMIC.

Design

Two-part model of cigarette demand with country fixed effects. The first part estimates the impact of prices on smoking participation while the second part estimates the impact of prices on the number of cigarettes smoked among current smokers. Besides controlling for individual characteristics such as Age, Gender, Parental Smoking and availability of Pocket Money, the authors control for confounding environmental factors such as anti-smoking sentiment, the prevalence of cigarette advertising and anti-tobacco media messAges, and ease of purchasing cigarettes. All countries in this study are represented with at least two observations over time, which allows us to control for unobserved country characteristics and/or policies that may influence smoking patterns within countries.

Results

Cigarette price is an important determinant of smoking. The estimated price elasticity of smoking participation is −0.74, and the estimated price elasticity of conditional cigarette demand is approximately −1.37. The total price elasticity of cigarette demand is −2.11, implying that an increase in price of 10% would reduce youth cigarette consumption by 21.1% at the mean.
Effects of different antimicrobial treatments on serum acute phase responses and leucocyte counts in pigs after a primary and a secondary challenge infection withActinobacillus pleuropneumoniae
Authors: Sjölund M. , Fossum C. , Martín de la Fuente A. J. , Alava M. , Juul‐Madsen H. R. , Lampreave F. , Wallgren P.
Published: July 2011

The susceptibility to an initial challenge and a re‐challenge inoculation withActinobacillus pleuropneumoniaewas analysed in pigs that were treated with antimicrobials of different efficacies following the first exposure toA pleuropneumoniae. In brief, 30 nine‐week‐old specific pathogen‐free pigs were allocated to five groups of six. After acclimatisation, four groups were inoculated withA pleuropneumoniaeserotype 2. At the onset of clinical signs, three of the groups of pigs were treated with enrofloxacin, tetracycline or penicillin. A fourth group served as the inoculated control and the fifth group as a control group that had not been inoculated. On day 28, all five groups were re‐challenged with the same strain ofA pleuropneumoniaeserotype 2 as had been used in the first inoculation. No treatments were carried out at this time. The acute phase responses and differential leucocyte counts were monitored in detail after both inoculations. Leucocytosis and acute phase responses in the forms of serum amyloid A, pig‐major acute phase protein and haptoglobin were recorded in all of the inoculated groups after the onset of clinical signs following the first inoculation. A porcine mannan‐binding lectin‐A response was less evident in the pigs. Acute phase responses resembling those of the first inoculation were observed in the pigs that had not previously been inoculated and in the pigs treated with enrofloxacin. Acute phase responses were not recorded in the other three groups, where the pigs had seroconverted toA pleuropneumoniaeserotype 2 following the first inoculation.
Phyllotactic transitions in seedlings: the case of Thuja occidentalis
Authors: Yin Xiaofeng , Lacroix Christian , Barabé Denis
Published: July 2011

The main goal of this study was to examine different phyllotactic patterns and pattern transitions in seedlings of eastern white cedar ( Thuja occidentalis L.). Four phyllotactic patterns were observed on the main stem of T. occidentalis: tetracussate, tricussate, (3, 5) spiral, and decussate. Only one phyllotactic pattern was observed on the side branches of T. occidentalis: decussate. Four types of phyllotactic pattern transition were observed: tetracussate to decussate, tetracussate to tricussate, tricussate to (3, 5) spiral, and (3, 5) spiral to decussate. For each phyllotactic pattern, the following phyllotactic parameters were examined using histological sections: divergence angle, plastochrone ratio, leaf insertion angle, parameter Г, and apical angle of the shoot apical meristem (SAM). Even though they varied widely, the phyllotactic parameters measured in T. occidentalis seem to fall within ranges observed in other plants for specific phyllotactic patterns. The results indicate that it is not possible to discriminate between the four different phyllotactic patterns observed on T. occidentalis by using the plastochrone ratio, leaf insertion angle, parameter Г, or apical angle of the SAM. In contrast to continuous transitions, where there is a good correlation between phyllotactic parameters, there was no correlation between the phyllotactic pattern (characterized by a given divergence angle) and other phyllotactic parameters in the discontinuous transitions observed in T. occidentalis.
Molecular phylogeny and reticulate origins of several American polyploid Hordeum species
Authors: Wang Huan , Sun Genlou
Published: July 2011

The phylogeny of diploid species in the genus Hordeum has been studied intensively. Although the origin of American polyploid species has been analyzed using multiple-copy internal transcribed spacer sequences, the origins of these species in Hordeum remain unclear. The objectives of our study were to elucidate the origins of American polyploid species and to explore phylogenetic relationships of these polyploids to diploid Hordeum and other diploid species in Triticeae using a single copy of a nuclear gene, disrupted meiotic cDNA1 (DMC1). DMC1 sequences from nine Hordeum polyploid species were analyzed. Sequence comparisons revealed that one copy of sequences from polyploid species Hordeum fuegianum , Hordeum jubatum , and Hordeum tetraploidum showed a 82 bp miniature inverted-repeat terminal element (MITE) (Stowaway) insertion, which was also detected in the Triticeae diploid species Australopyrum species (W genome) and Taeniatherum caput-medusae (Ta genome). Maximum parsimony and Bayesian analysis suggested that diploid Hordeum brachyantherum subsp. californicum is one ancestor of polyploids Hordeum arizonicum , H. brachyantherum subsp. brachyantherum , Hordeum depressum , and Hordeum procerum . The other ancestor of tetraploid H. depressum is probably Hordeum euclaston . Hordeum cordobense was suggested to be one of the genome donors to hexaploid H. procerum. The diploid Hordeum flexuosum and tetraploid H. tetraploidum were suggested as the parents to hexaploid species Hordeum parodii . The result is that one sequence from each of three Hordeum tetrapolyploids, including H. fuegianum, H. jubatum, and H. tetraploidum, and one from Hordeum hexaploid H. arizonicum fall outside the Hordeum clade of the DMC1 phylogenetic tree, therefore representing another example of complex evolutionary history. Our data may shed light on future phylogenetic studies in Triticeae, especially for the polyploids, by broadening the scope of investigations through sampling more genome types in Poaceae, not only from the tribe Triticeae.
The thickness of Neogene and Quaternary cover across the central Interior Plateau, British Columbia: analysis of water-well drill records and implications for mineral exploration potential1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia. 2Geological Survey of Canada (GSC) Contribution 20100036; Mineral Deposit Research Unit (MDRU, Department of Earh and Ocean Sciences, The University of British Columbia) Contribution p-261.
Authors: Andrews Graham D.M. , Plouffe Alain , Ferbey Travis , Russell James K. , Brown Sarah R. , Anderson Robert G.
Published: July 2011

Analysis of over 10 000 water-well records has been used to produce new depth-to-bedrock maps for areas around five cities on the central Interior Plateau of central British Columbia: 100 Mile House, Prince George, Quesnel, Vanderhoof, and Williams Lake. Hitherto, exploration for mineral and hydrocarbon resources has been hampered by a lack of basic knowledge of the thickness of Neogene and Quaternary lithologies. Interpretation of these new maps provides first-order constraints on the localization of thick drift in pre-Late Wisconsinan bedrock paleovalleys, some of which are now buried. Basalt lavas of the Chilcotin Group are restricted to erosional remnants of previously extensive sheets emplaced onto an older peneplain. Our results confirm that the Neogene and Quaternary cover is primarily controlled by paleotopography and is generally thin and patchy across much of the region. Increased understanding of the three-dimensional distribution of cover produces a corresponding increase in the utility of geological, geochemical, and geophysical exploration techniques, and a reduction in the risk for future mineral exploration activities, especially when combined with more sophisticated data sets.
Near-surface and crustal-scale images of the Nechako basin, British Columbia, Canada, from magnetotelluric investigations1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.2Geological Survey of Canada, GSC Contribution No.: 20100129.
Authors: Spratt Jessica , Craven Jim
Published: July 2011

Two-dimensional (2-D) models of audio and broadband magnetotelluric (MT) data collected throughout the southern Nechako basin in south–central British Columbia, Canada, provide electrical resistivity images of the Cretaceous to Oligocene volcanic and sedimentary packages and underlying crustal-scale features. Analysis of distortion effects and structural dimensionality indicate that the MT responses are primarily one-dimensional (1-D) at periods less than 0.1 s. Departures from a 1-D response occur with maximum phase differences occurring between 0.1 and 10 s. The upper crustal resistivity models reveal a low resistivity layer at near surface depths, interpreted as Chilcotin basalts, that blankets portions of the region to depths less than 50 m, but locally thicken up to 200 m. Cretaceous sedimentary units (those showing the highest potential for hydrocarbons) are characterized by moderately low resistivities that are laterally variable. More uniform, lower resistivities appear to be associated with the Eocene volcaniclastic groups, suggesting that the MT method can distinguish between these units and may be useful in targeting areas that are more prospective for hydrocarbon exploration. In general midcrustal resistivity values are high, consistent with values of typical volcanic terranes; however, a low-resistivity zone is identified at 8–10 km depth that correlates closely with the location of seismic reflectors as well as recent microseismic activity. This low-resistivity zone is interpreted as a midcrustal reservoir of magma, the top of which marks the upper limit of fluids migrating from lower crust depths. Additionally, several crustal-scale faults are imaged.
Integrating ice-flow history, geochronology, geology, and geophysics to trace mineralized glacial erratics to their bedrock source: An example from south-central British Columbia1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.2Earth Sciences Sector Contribution Number: 20100079.
Authors: Plouffe A. , Anderson R.G. , Gruenwald W. , Davis W.J. , Bednarski J.M. , Paulen R.C.
Published: July 2011

This study demonstrates how ice-flow history, geochronology, geology, and geophysics may be integrated to enhance the effectiveness of boulder tracing in glaciated regions affected by multiple ice-flow events. Mineralized felsic granitoid boulders (erratics) were discovered 18 years ago on a claim block located 10 km northwest of Little Fort, in the Bonaparte Lake map area (NTS 092P), in south-central British Columbia. Although the boulders have yielded significant gold concentrations (up to 4.15 g/t), their bedrock source is not known. The till near the boulders contains up to 1382 gold grains per 15 kg of bulk material with 75% of the grains having pristine morphology, suggesting a short distance of glacial transport. A U–Pb zircon crystallization age of 198.1 ± 0.5 Ma on one mineralized boulder indicates derivation from an Early Jurassic intrusion. Using a vector addition model based on regional ice-flow patterns, the most recent and detailed bedrock geology map, and recently acquired airborne radiometrics and magnetic data, the northeast sector of the Thuya Batholith (195–205 Ma) is interpreted as the most likely bedrock source of the mineralized boulders.
Interpretation of structures in the southeastern Nechako Basin, British Columbia, from seismic reflection, well log, and potential field data1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.2Geological Survey of Canada Contribution 20100002.
Authors: Hayward Nathan , Calvert Andrew J.
Published: July 2011

The structure and stratigraphy of the southeast Nechako Basin, which are poorly understood primarily because of substantial volcanic cover, are investigated in an analysis of seismic reflection, well, and potential field data. Formation and development of the SE Nechako Basin resulted in sub-basins containing Cretaceous and Eocene rocks. Interpretation reveals that dextral transtension in the Early to Middle Eocene created NNW-trending, en echelon, strike-slip faults linked by pull-apart basins, which locally contain a thickness of Eocene volcaniclastic rocks of >3 km. This structural pattern is consistent with regional observations that suggest the transfer of slip from the Yalakom fault to the north via a series of en echelon strike-slip faults. In the Middle to Late Eocene, faults associated with a change in the direction of stress, echoed by the north-trending right-lateral Fraser fault, reactivated and cut earlier structures. A simple model agrees with local observations, that northeast-directed compression was subparallel to the relic Cretaceous grain. Cretaceous rocks are discontinuous throughout the basin and may be remnants of a broader basin, or a number of contemporaneous basins, formed in a regional transpressional tectonic setting that caused northeast-directed thrusting along the eastern side of the Coast Plutonic Complex. Results suggest that thrusting affected most of the SE Nechako Basin, as observed across the Intermontane Belt to the northwest and southeast. The pattern of deposition of Neogene volcanic rocks of the Chilcotin Group was in part controlled by the Eocene structural grain, but we find no evidence of Neogene deformation.
The Jackass Mountain Group of south-central British Columbia: depositional setting and evolution of an Early Cretaceous deltaic complex1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.2Earth Science Sector (ESS) Contribution 20100280.
Authors: MacLaurin Catherine I. , Mahoney J. Brian , Haggart James W. , Goodin J. Russell , Mustard Peter S.
Published: July 2011

The Lower Cretaceous Jackass Mountain Group of southwestern British Columbia records a complex history of deltaic and proximal marine sedimentation in a tectonically active area of the Canadian Cordillera. Two Jackass Mountain Group successions, exposed in the Camelsfoot Range and Chilko Lake regions and separated by ∼125 km across the northwest–southeast-trending Yalakom fault, provide details of stratigraphy, sedimentology, petrography, and geochemistry of the group. Restoring dextral movement across the Yalakom fault indicates that these locales were adjacent to one another during deposition; data presented herein support this reconstruction. In addition, detailed sedimentological investigations reveal widespread shallow-marine and deltaic features, indicating that deposition occurred predominantly within a large, shallow-water deltaic system. This interpretation is crucial to the understanding of regional facies patterns and for predicting hydrocarbon potential in adjacent subsurface rocks. New porosity, permeability, and thermal maturity data augment information collected from Jackass Mountain Group strata in the subsurface and indicate that some units represent potential hydrocarbon source rocks.
Source rock potential of Lower to Middle Jurassic black clastic sequences of the Intermontane belt1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.
Authors: Ferri Filippo
Published: July 2011

Lower to Middle Jurassic clastic sequences are widespread within the interior of the Canadian Cordillera. These successions cap waning Jurassic volcanism in many Cordilleran arc terranes and are succeeded by clastic sequences of the Intermontane basins. Fine-grained, carbonaceous lithologies, which locally contain elevated levels of organic carbon, characterize these clastic successions. These include sections of the Spatsizi Formation (Abou Member) and Smithers Formation in northern and western Bowser basin, respectively, Ashcroft Formation and equivalent strata in central Quesnellia, and Last Creek Formation and Junction Creek rocks below the Tyaughton–Methow basin. These rocks locally contain metre-thick sections with total organic carbon (TOC) levels >5 wt.% and others have thicknesses approaching 100 m with TOC between 3 and 5 wt.%. Thermal maturation levels are high in many sections, suggesting original organic contents were greater and that these rocks may have been excellent source beds. Associated bitumen in these successions, together with Mesozoic oil in some overlying Intermontane clastic rocks, also suggests these sequences may have been effective oil source rocks. TOC levels, thermal maturity, and thickness of some sections are comparable with shale gas sequences being exploited elsewhere in North America. TOC concentrations within these rocks, together with other elemental abundances, indicate anoxic conditions during deposition. The age of these clastic rocks brackets the global Toarcian anoxic event and that of other organic-rich sequences in North America. Elemental abundances suggest predominantly volcanic-arc complexes as source terranes, although continental signatures are suggested by rocks in western Quesnellia.
Bond strength in concrete filled built-up steel tube columns with tab stiffeners
Authors: Petrus Clotilda , Abdul Hamid Hanizah , Ibrahim Azmi , Nyuin Joe Davylyn
Published: July 2011

Apart from strength and ductility, adequate bond between steel and concrete at the interface is important in concrete filled steel tube (CFST) columns to ensure a composite action. One way of improving the bond strength of a CFST column is introducing internal stiffeners. This paper presents an experimental investigation into the bond strength of a CFST column with tab stiffeners by conducting a push out test. Twenty-one square specimens of sides 200 mm × 200 mm, fabricated from 2 mm thick mild steel sheeting were tested in two series. The first series considered the variation in the tab spacing along the stiffeners, namely 75, 100, 150, and 300 mm, while in the second series, the concrete cube compressive strengths were 36, 40, and 50 MPa. The bond strength at the concrete–steel interface was found to increase with decreasing tab spacing. In-filling the tubes with higher strength concrete had also resulted in an increase in the bond strength by up to an average of 40%.
Combination rule for the prediction of the seismic demand on columns of regular bridges under bidirectional earthquake components
Authors: Khaled Amar , Tremblay Robert , Massicotte Bruno
Published: July 2011

A percentage rule for the prediction of interacting seismic responses of bridge columns under multi-directional earthquake components is derived for eastern and western Canada seismic regions. A total of 14 regular bridges with different geometrical properties were examined for the two sites. The new rule was developed by comparing the column longitudinal steel ratio required from response spectrum analysis with combination rules to the ratio determined from the results of linear dynamic time history analysis of the bridge structures under bidirectional ground motions. The required steel ratios were found to vary with the weighted percentages used in the combination rules, the ground motion characteristics, and bridge properties. It was found that a 100%–20% combination rule is applicable for most bridges studied in eastern Canada. A 100%–40% rule is more appropriate for bridges located in western Canada. The results show that these rules need not be applied for regular straight bridges without skew but further investigation is needed before such a relaxation can be applied. Nonlinear dynamic time histories analysis of a two-span skewed bridge designed with the proposed percentage rule for eastern and western Canada showed that the columns would not experience excessive damage.
Morphology and genesis of deep scour holes in the Mackenzie Delta
Authors: Beltaos Spyros , Carter Tom , Prowse Terry
Published: July 2011

A unique feature that has been detected in the course of past morphological studies of Mackenzie delta channels, and which is of particular concern to the design of pipeline crossings, is the frequent occurrence of very deep scour holes. A recent survey along East Channel revealed many additional holes, with maximum depths ranging from 13 to 37 m. Using the results of recent and past surveys, an inventory of known scour holes and associated morphological parameters is developed. Most holes occur near bends, and often next to recesses in the channel boundaries, known as scour bays. It is shown that presence of scour bays indicates deeper-than-expected holes while repeat surveys of three holes indicate stability. Previously postulated formative mechanisms of bay-associated holes are critically examined; scour under ice jams is eliminated while lake capture is considered likely. Practical implications of the present findings are discussed and research needs outlined.
Mechanical capabilities and fire endurance of natural rubber latex modified concrete
Authors: Ismail Mohammad , Muhammad Bala , Yussuf Abdirahman Ali , Majid Zaiton , Ismail Mohamed ElGelany
Published: July 2011

Compressive, indirect tensile, and flexural strengths characteristics of natural rubber latex modified concrete (NRLMC) were studied and reported — Part I. In addition, a comparative investigation between normal concrete (NC) and NRLMC, conducted on fire endurance was also presented — Part II. Normal and modified elements containing latex–water ratios within 0–10% were prepared and cured in accordance with the Japan Industrial Standard. Fire endurance capacity was assessed at five temperature levels; ambient temperature (27 °C), 150, 300, 500, and 800 °C. However, elevated heating (800–1300 °C) was further applied for the purpose of monitoring behavior at the verge of disintegration. Specimens were allowed to cool in the oven prior to compressive strength tests until room temperature is attained. Test results indicate that significant mechanical capabilities could be achieved by the inclusion of an appropriate quantity of latex concentrate and proper selection of befitting curing regime. Interestingly, the superiority of NRLMC over NC is maintained even under fire, up to the critical limit of latex-film capability performance.
New and improved channel cross section with piecewise linear or smooth sides
Authors: Easa Said M.
Published: July 2011

This paper presents a new and improved channel cross section with m-segment linear sides and horizontal bottom (MSLS). For large m, the section sides become smooth curves, thus providing the designer with flexibility in using either piecewise linear or smooth channel sides with the same formulation. General simple formulas for the area and perimeter are presented for section sides with m linear segments. An optimization model, which implements the general formulas and minimizes the construction cost, is presented and applied using an example. For sections with piecewise linear sides, where the surface lining unit cost increases as the number of sides increases, the MSLS section was found to be more economical than a section with two-segment linear sides when the rate of increase in cost is not large. The smooth MSLS was found to be always more economical than the two-segment parabolic side section and the parabolic side section. The MSLS, which is more economical, yet simpler, than other section types is useful for a wide range of applications involving small and large channels.
Open channel flow recovery in the wake of a flat plate on rough beds
Authors: Krampa F.N. , Balachandar R.
Published: July 2011

The flow recovery in the wake of a surface-mounted flat plate is investigated in an open channel. The plate with a thickness-to-chord ratio (t/c) of 0.12 is placed with the chord parallel to the flow. The characteristics of the mean velocity and higher-order statistics obtained along the wake axis upstream and downstream of the plate are discussed in the presence of bed roughness. Inner scaling of the mean velocity profile shows a depression in the outer region of the flow. The near-wall portion of the velocity profile in the plate wake region was found to recover faster to the upstream state. The profiles of the turbulent intensity in the plate wake deviate from the upstream profiles and recover gradually with downstream distance. The upstream turbulent intensities for the wire-mesh rough surface peak at farther wall normal locations compared to those of the sand grain and smooth surfaces. A similar roughness effect was observed at the downstream locations amidst the distorted flow, especially, in the intermediate and far wake regions. In the near- and intermediate-wake regions, both the velocity skewness and flatness factors data for the rough walls were higher compared to the data for the smooth surface. For all surfaces, even at the last measuring station (x = 200t) considered in the study, the skewness and flatness factors were found to be still recovering to the upstream condition.
DEVELOPMENT OF ANALYSIS SYSTEM OF MICRO-IBIL COMBINED WITH MICRO-PIXE
Authors: KADA W. , YOKOYAMA A. , KOKA M. , SATOH T. , KAMIYA T.
Published: July 2011

An ion beam induced luminescence analysis system using ion micro-beam (micro-IBIL) was newly developed on the microbeam system of the 3 MeV single-ended accelerator at ion-irradiation research facility TIARA, JAEA. The developed IBIL system consisted of an aspheric microlens, optical fibers, a monochromator and a photon-counting system to observe IBIL photons of specific wavelength with the resolution of 2 nm. A photomultiplier in the photon-counting system was cooled to around 0°C by a peltier device to reduce the background noises down to 10 cps and able to observe weak photon signals from specific chemical composites of the target. Experiments of micro-IBIL were performed using 3 MeV proton microbeam for several scintillators and particulate targets i.e. aerosol particles. The system had achieved chemical-imaging of aerosols by obtaining wavelength-dispersive micro-IBIL image at luminescence center of silicon dioxide.
EVALUATION OF THIN SECTION STANDARDS FOR LOCAL ANALYSIS OF LIGHT ELEMENTS BY MICRO-PIXE ANALYSIS
Authors: HOMMA-TAKEDA SHINO , SUZUKI KYOKO , HARUMOTO KEIKO , YOSHITOMI TOMOYASU , ISO HIROYUKI , ISHIKAWA TAKAHIRO , KONISHI TERUAKI , OIKAWA MASAKAZU
Published: July 2011

For quantitative measurements of light elements by micro-PIXE (particle-induced X-ray emission) analysis, suitable external standards have been expected. In this paper thin sections of polyvinyl alcohol solution containing phosphorus ( P ) and potassium ( K ) were assessed for their purpose as standards by micro-PIXE analysis. Homogeneity of P and K added to the standard materials were validated by 1 μm and 10 μm-step scanning of the standard. The relative standard deviations of the X-ray intensity of the standards P and K were < 25% and <16%, respectively. The calibration line between the X-ray intensity obtained from a 100 × 100 μm2 area and the elements concentration was also acceptable, indicating that the thin section standards are adequate for an external standard of micro-PIXE measurements for light elements.
FLUORIDE UPTAKE INTO HUMAN TEETH FROM A FLUORIDE-RELEASING THIN LAYER AFTER A LONG PERIOD OF FILLING
Authors: YAMAMOTO HIROKO , IWAMI YUKITERU , EBISU SIGEYUKI , KOMATSU HISANORI , NOMACHI MASAHARU , SUGAYA YORIHITO , YASUDA KEISUKE
Published: July 2011

Fluoride ( F ) distribution in human teeth was measured using an in-air micro-PIGE and micro-PIXE system. Class V cavities in the extracted teeth were prepared with Fluoro-Bond Shake One to provide a thin layer of an F-releasing material (FRM). The cavities were then filled with Beautifil Flow F10 (FRM, Group I) or LITE FIL IIP (non-FRM, Group II). Following a four-year period, specimens were cut longitudinally perpendicular to the cavity floor. The F distribution was measured at the floor of the cut surface. The position including 90% of the intact Ca level was defined as the wall surface. Based on this demarcation, indices of F distribution (surface F concentration and F penetration depth) were determined. Thickness of FRM thin layers varied (≈339 μm) and did not affect F distribution. Both values of F distribution indices in Group I [821–8763 (mean 3797) ppm, 34–668 (mean 241) μm] were significantly larger than those in Group II [0–7064 (mean 1865) ppm, 0–143 (mean 21) μm]. The F distribution in Group I was affected more by the filling material than by the FRM thin layer during the four-year exposure. Methodologies using this system may give insightful information for the development of new dental materials.