bluuebunny/crossref_metadata_2025 huggingface dataset:
The Transcriptional Regulator Rv0485 Modulates the Expression of a
pe
and
ppe
Gene Pair and Is Required for
Mycobacterium tuberculosis
Virulence
Authors: Goldstone Rachael M. , Goonesekera Sunali D. , Bloom Barry R. , Sampson Samantha L.
Published: August 2009

The
pe
and
ppe
genes are unique to mycobacteria and are widely speculated to play a role in tuberculosis pathogenesis. However, little is known about how expression of these genes is controlled. Elucidating the regulatory control of genes found exclusively in mycobacteria, such as the
pe
and
ppe
gene families, may be key to understanding the success of this pathogen. In this study, we used a transposon mutagenesis approach to elucidate
pe
and
ppe
regulation. This resulted in the identification of Rv0485, a previously uncharacterized transcriptional regulator. Microarray and quantitative real-time PCR analysis confirmed that disruption of Rv0485 reduced the expression of the
pe13
and
ppe18
gene pair (Rv1195 and Rv1196), defined the Rv0485 regulon, and emphasized the lack of global regulation of
pe
and
ppe
genes. The in vivo phenotype of the Rv0485 transposon mutant strain (Rv0485::Tn) was investigated in the mouse model, where it was demonstrated that the mutation has minimal effect on bacterial organ burden. Despite this, disruption of Rv0485 allowed mice to survive for significantly longer, with substantially reduced lung pathology in comparison with mice infected with wild-type
Mycobacterium tuberculosis
. Infection of immune-deficient SCID mice with the Rv0485::Tn strain also resulted in extended survival times, suggesting that Rv0485 plays a role in modulation of innate immune responses. This is further supported by the finding that disruption of Rv0485 resulted in reduced secretion of proinflammatory cytokines by infected murine macrophages. In summary, we have demonstrated that disruption of a previously uncharacterized transcriptional regulator, Rv0485, results in reduced expression of
pe13
and
ppe18
and attenuation of
M. tuberculosis
virulence.
Oxygen-isotopic composition of basalts from young spreading axes in the eastern Pacific
Authors: Barrett T. J. , Friedrichsen H.
Published: August 2009

Oxygen-isotopic composition data are reported for young oceanic basalts from two different tectonic settings in the eastern Pacific: (1) the uppermost basement on the Galapagos Rift (< 1 Ma old), and (2) subbasement depths up to ≈150 m in the Gulf of California (≤ 3.5 Ma old). In the Galapagos area, whole-rock δ18O values exhibit a narrow range of 5.7–6.6‰, consistent with minimal to slight low-temperature alteration. Limited alteration probably reflects a combination of young basement age, low temperatures for solutions in the uppermost basement, and confinement of solutions mainly to discrete fractures. In the Gulf of California, by contrast, high whole-rock values are found at site 474A, near the Baja margin, where the greatest range in δ18O also occurs, from 2.5 to 12.5‰. This indicates considerable variation in both the temperature and degree of alteration at this site, probably a consequence of the heterogeneous basement sequence (intercalated pillow lavas, sills, and wet sediments). Differences in δ18O of up to 6‰ can exist over several metres, implying sharp changes in temperature or local water/rock ratio. The development of low-temperature alteration is more pronounced at site 474A (≈3.5 Ma) than at the several other (younger) crustal locations drilled in the Gulf of California, presumably because of longer exposure to seawater during recession of site 474A from the spreading axis.Analysis of primary magmatic phases at all sites yield 18O fractionations between plagioclase, clinopyroxene, and magnetite consistent with crystallization in a closed system and without high-temperature subsolidus reaction with seawater oxygen (even where sediments are intercalated within the basement). At site 485 in the Gulf of California, a thick basaltic sill yielded the lowest calculated crystallization temperatures (920 ± 50 °C) on the basis of plagioclase–magnetite fractionations; this agrees reasonably with groundmass quartz estimated to have formed at 860 ± 40 °C. Two vein carbonates from the uppermost part of the igneous sequence at this site were formed at temperatures of less than a few tens of degrees.We also report high-precision strontium- and oxygen-isotopic data on mineral separates from four basalts recovered at site 504B (6 Ma old). The most striking feature of these data is very substantial contamination of most mineral phases by seawater Sr, even though the same splits have typical primary magmatic oxygen-isotopic values. Relative to an unaltered mid-ocean ridge basalt 87Sr/86Sr value of 0.70265 ± 0.0001, 87Sr/86Sr ratios of plagioclase range from 0.70270 to 0.70359 (for apparently primary δ18O values of 5.35–5.75‰); for clinopyroxene, 87Sr/86Sr ratios range from 0.70309 to a very enriched value of 0.70695 (δ18O values of 4.97–5.30‰, with one value of 6.05‰). These results indicate that young basalts may have experienced significant interaction with seawater, which is not recorded in terms of oxygen-isotope exchange.
The characteristics and significance of secondary magnetite in a profile through the dike component of the Troodos, Cyprus, ophiolite
Authors: Hall J. M. , Fisher B. E.
Published: August 2009

Secondary magnetite (SM) is the dominant Fe–Ti oxide over a 3–4 km thick vertical interval in a profile through the Troodos, Cyprus, ophiolite. SM is important in dikes and flows where dike density exceeds about 30% within the transition from extrusives to sheeted dikes and remains important until dike density falls below about 30% in the transition from sheeted dikes to plutonics. The association of SM with high dike density suggests that it is a product of the thermal metamorphism of hydrothermally metamorphosed dikes and flows. The most common occurrence of SM is at the site of primary titanomagnetites that had been altered earlier through deuteric, low-temperature, and regional hydrothermal alteration processes. SM often closely pseudomorphs the form of primary magnetite (PM) grains, but it can be distinguished from PM using a series of criteria. SM is low in TiO2 and other impurities. Estimated and observed Curie temperatures are undistinguishable, which, combined with optical evidence, indicates that SM is probably approximately stoichiometric.SM may also be present at depth in in situ oceanic crust, in other ophiolites, and in other hydrothermally altered volcanic sequences where the density of minor intrusions is sufficiently high.The formation of SM leads to the annealing of the features of altered PM that provide the ability to retain strong, stable remanent magnetization. In appropriate combinations of the timing of formation of SM and of geomagnetic field reversals, the different parts of a volcanic sequence may be magnetized with opposite polarities.
Compositional characteristics of the Kenora–Kabetogama dyke swarm (Early Proterozoic), Minnesota and Ontario
Authors: Southwick D. L. , Halls H. C.
Published: August 2009

Over a 100 new major-element analyses and 48 analyses for a restricted suite of minor and trace elements have been made on samples from 31 localities in the Kenora–Kabetogama (KK) dyke swarm of Minnesota and northwestern Ontario. A subset of 14 analyses, selected to minimize the aberrations of secondary hydrous alteration, flow layering, and oversampling bias, characterizes the range of dyke compositions. The dykes are interpreted as having been derived from a single magma type; their compositions span a smooth continuum of MgO and TiO2 variations. The magmatic system was tapped most vigorously at two stages: at a relatively early stage when the magma contained about 7.6% MgO and 0.9% TiO2, and again at a later stage when the magma contained about 5.5% MgO and 2.2% TiO2. Large master dykes (~100–190 km long) and many smaller dykes are of these two compositions. Dykes throughout the compositional spectrum are indistinguishable paleomagnetically. Available radiometric data suggest that KK magmatism may have been prolonged (> 100 Ma?), but the paleomagnetic results suggest a much shorter probable life-span.The KK swarm is related to tectonic activity in the Penokean orogen (Early Proterozoic). It may have developed as a manifestation of peripheral foreland bulging initiated by thrust loading of the crust in the hinterland of the Animikie basin.
Geology of the Cadwallader Group and the Intermontane–Insular superterrane boundary, southwestern British Columbia
Authors: Rusmore Margaret E.
Published: August 2009

Several lower Mesozoic, fault-bounded units separate the Intermontane and Insular superterranes in southwestern British Columbia. Detailed study of one of these Mesozoic units, the Cadwallader Group, helps clarify the boundary between the superterranes and establish the tectonic evolution of southwestern British Columbia. The Cadwallader Group is the oldest unit in an Upper Triassic through Middle Jurassic volcanic and sedimentary tectono-stratigraphic terrane. Two formations, the Pioneer and the Hurley, compose the Cadwallader Group; the previously recognized Noel Formation is no longer considered valid. The Pioneer Formation contains pillow basalt, flows, and basalt breccia. Siltstone, sandstone, conglomerate, and minor amounts of limestone megabreccia and basalt belonging to the Hurley Formation conformably overlie the Pioneer. The Hurley spans latest Carnian or earliest Norian to middle Norian time. Two episodes of deformation affected the Cadwallader, and a thrust fault separates the group from slightly younger clastic rocks of the Tyaughton Group. Similarities in clastic rocks indicate the Tyaughton was deposited on the Cadwallader; together the units form the Cadwallader terrane. Basalts and clastic rocks in the terrane record deposition in or near a Carnian to earliest Norian volcanic arc. Volcanism waned later in the Norian, but presence of the arc is preserved in the clastic rocks.Oceanic rocks of the Middle Triassic to Middle Jurassic Bridge River terrane became juxtaposed with the Cadwallader terrane in Middle Jurassic time, after which the terranes functioned as a single tectonic block. Contrasting volcanic histories suggest that the Cadwallader terrane was not accreted to the Intermontane superterrane until Middle Jurassic or Early Cretaceous time, although the similar tectonic settings of Stikinia and the Cadwallader terrane allow a common earlier history. The Cadwallader terrane is not part of either the Alexander terrane or Wrangellia, and so the inboard margin of the Insular superterrane must lie west of the Cadwallader terrane.
Drumlin formation by subglacial meltwater erosion
Authors: Shaw John , Sharpe David R.
Published: August 2009

Some drumlins are shown to belong to a family of remnant erosional ridges associated with subglacial meltwater. The lengths of these ridges vary in scale from a few tens of millimetres to over 5 km. Similar form elements are illustrated for three scales of forms. It is concluded that some drumlins are composed of preexisting sediment or bedrock left upstanding in ridges as a result of the removal of surrounding materials. This erosional theory is related to an earlier theory in which drumlins are held to result from the infilling of subglacial cavities. The unifying factor for both theories is the role of sheets of subglacial meltwater.
The initiation of the early Paleozoic Cordilleran miogeocline: evidence from the uppermost Proterozoic – Lower Cambrian Hamill Group of southeastern British Columbia
Authors: Devlin William J. , Bond Gerard C.
Published: August 2009

The uppermost Proterozoic–Lower Cambrian Hamill Group of southeastern British Columbia contains geologic evidence for a phase of extensional tectonism that led directly to the onset of thermally controlled subsidence in the Cordilleran miogeocline. Moreover, the Hamill Group contains the sedimentological record of the passage of the ancient passive margin from unstable tectonic conditions associated with rifting and (or) the earliest phases of thermal subsidence to post-rift conditions characterized by stabilization of the margin and dissipation of the thermal anomaly generated during the rift phase (the rift to post-rift transition). Widespread uplift that occurred prior to and during the deposition of the lower Hamill Group is indicated by an unconformable relation with the underlying Windermere Supergroup and by stratigraphic relations between Middle and Upper Proterozoic strata and unconformably overlying upper Lower Cambrian quartz arenites (upper Hamill Group) in the southern borderlands of the Hamill basin. In addition, the coarse grain size, the feldspar content, the depositional setting, and the inferred provenance of the lower Hamill Group are all indicative of the activation of basement sources along the margins of the Hamill basin. Geologic relations within the Hamill Group that provide direct evidence for extensional tectonism include the occurrence of thick sequences of mafic metavolcanics and rapid vertical facies changes that are suggestive of syndepositional tectonism.Evidence of extensional tectonism in the Hamill Group directly supports inferences derived from tectonic subsidence analyses that indicate the rift phase that immediately preceded early Paleozoic post-rift cooling could not have occurred more than 10–20 Ma prior to 575 ± 25 Ma. These data, together with recently reported isotopic data that suggest deposition of the Windermere Supergroup began ~730–770 Ma, indicate that the rift-like deposits of the Windermere Supergroup are too old to represent the rifting that led directly to the deposition of the Cambro-Ordovician post-rift strata. Instead, Windermere sedimentation was apparently initiated by an earlier rift event, probably of regional extent, that was part of a protracted, episodic rift history that culminated with continental breakup in the latest Proterozoic – Early Cambrian.
Retrograde eclogite from Mont Albert, Gaspé, Quebec
Authors: Trzcienski Jr. Walter E.
Published: August 2009

Retrograde eclogite is found along the northern perimeter of ultramafic rocks in the Mont Albert complex, Gaspé, Quebec. Garnet–clinopyroxene geothermometry gives 840 °C as the peak temperature of metamorphism. Kyanite in associated metapelites requires that, at this temperature, pressure be a minimum of 12 kbar. Based on symplectic textures in the eclogitic and associated rocks and clinozoisite – white mica – quartz– plagioclase equilibria, a counterwise pressure–temperature trajectory that terminates near 500 °C and 8 kbar can be traced for the Mont Albert complex.
Methane and hydrogen in mid-ocean-ridge basalt glasses: analysis by vacuum crushing
Authors: Welhan J. A.
Published: August 2009

A comparative study of vacuum crushing methods for analyzing reactive gases in basaltic glasses shows that ball milling is an efficient means of releasing occluded gases but that blank production represents a potentially serious problem that must be accounted for when determining reactive-gas compositions. Production of H2 and CH4 in a stainless-steel ball mill in the absence of rock material increases with length of crushing time. However, test results presented here indicate that blank levels are reduced during the actual crushing process by the presence of rock powder, which may act as a cushion to reduce metal–metal contact. Crushing in copper tubes under a hydraulic press produces no blanks for these gases, but crushing efficiency and gas release are very low, and gas adsorption on rock powder becomes a significant problem. Experiments with methane adsorption on crushed basalt suggest that the loss of methane is a chemisorption process that is, for the most part, irreversible.Applying corrections for these effects, we find that H2/CH4 ratios (~3 – 30) in mid-ocean-ridge basalt glasses are similar to those seen in high-temperature mid-ocean-ridge hydrothermal fluids. These data, arguments based on the similarity of water/rock mass ratios calculated from basalt gas data, and the uniformity of methane/helium ratios in divers high-temperature mid-ocean-ridge hydrothermal fluids support the contention that dissolved CH4 and H2 in these fluids are predominantly derived from leaching of mid-ocean-ridge basalt.
Differential attrition of molluscan shells in freshwater sediments
Authors: Pip Eva
Published: August 2009

Mean seasonal species composition of living molluscan communities was compared with the composition of current dead assemblages in the sediments of three sites located in the Delta Marsh of southern Lake Manitoba. Dead shells were more numerous in vegetated than in bare areas, resulting primarily from the affinities of living molluscs for vegetated areas. Redistribution patterns of empty shells were not significantly different for vegetated and bare areas, as judged from distributions of passively transported land shells in the sediments. Significant differences were observed at all sites between species frequencies in living and corresponding dead assemblages averaged for the season. Proportions of living to dead individuals per unit bottom area indicated higher attrition rates with increasing energy conditions as well as with increasing shell size. Differential attrition may result in overrepresentation of small species in fossil assemblages.
North Mountain basalt from Digby, Nova Scotia: models for a fissure eruption from stratigraphy and petrochemistry
Authors: Papezik V. S. , Greenough John D. , Colwell John A. , Mallinson Terry J.
Published: August 2009

The early Mesozoic, quartz normative, North Mountain basalts in southwestern Nova Scotia (Digby area) form three units: a coarse massive lower flow (~190 m) bearing minor lenses of mafic pegmatite, a middle unit of thin amygdaloidal basaltic flows (~50 m), and an upper flow unit of massive phenocryst-rich basalt (~160 m). The two thick units show phenocrysts of orthopyroxene (bronzite) and (or) pigeonite, augite, and zoned plagioclase in a granular matrix of augite, pigeonite, and plagioclase. Variation diagrams and chondrite-normalized rare-earth-element patterns relate all chemical diversity between and within flows to removal and (or) accumulation of plagioclase and pyroxene phenocrysts (~1:1). High K, Rb, and Ba, appear related to assimilation of continental crust. Constancy of fractionation-independent element ratios and variations in phenocryst content vertically and along the 200 km strike of the basalts suggest (1) crystal settling and accumulation together with assimilation and mixing in a lower crustal magma chamber, (2) rise to upper crustal levels in a central conduit followed by northeast-ward emplacement along a tension-induced dyke system, and (3) extrusion along a fissure in two major and numerous minor pulses that formed the lower, upper, and middle units. Assimilation did not occur as magma moved through the dyke system, for assimilation-related variations in composition do not occur along strike.
Origin of salt in coastal marshes of Hudson and James bays
Authors: Price Jonathan S. , Woo Ming-Ko
Published: August 2009

The presence of salt in isostatically uplifted coastal marshes well removed from tidal sources suggests that the salt is relict in origin. This was confirmed by the measured downward increase in salinity towards the deeper and older Tyrrell Sea sediments and by the presence of water isotopically heavier than the present-day meteoric or tidal waters. The low permeability of marsh sediments and the vertical distribution of salt indicate that diffusion is transmitting salt toward the surface, where it is subsequently removed by surface flow. Salt concentration decreases with distance inland, where the salt-loss processes have proceeded for a longer time. The chloride concentration of the deep pore water suggests that the total salinity of the postglacial Tyrrell Sea was 21–25 g L−1.
A fault-bounded outlier of Archean clastic rocks near Thunder Bay, Ontario
Authors: Kehlenbeck M. M.
Published: August 2009

A fault-bounded clastic sedimentary sequence occurs as an outlier in contact with a terrane of Archean metavolcanic rocks. In addition to a regional penetrative fabric, the rocks of the clastic sequence possess a crenulation cleavage that is axial planar to a set of minor, north-plunging folds. Abundant faulting of the clastic rocks has resulted in significant internal disruption of the sequence as a whole and suggests it is a down-faulted block of a basin structure.
Distinguishing barren and auriferous veins in the Sigma Mine, Val-d'Or, Quebec
Authors: Sherlock Ross L. , Jowett E. Craig , Smith Brian D. , Irish Donald E.
Published: August 2009

The Sigma Mine is an Archean lode gold deposit located in the Abitibi greenstone belt, Quebec. Barren quartz veins occur subparallel to auriferous veins within the mine and also occur north of the mine. The quartz and auriferous veins exhibit a similar mineralogy and alteration and are indistinguishable except for the presence or absence of gold. This study determines differences between (i) a vein that may be auriferous but lacks gold at that location and (ii) a barren vein that formed from fluids that never had the capability of carrying gold. Microthermometry distinguishes two distinct salinities within aqueous inclusions in the barren veins, compared to high salinities only reported in the auriferous veins. The CO2–H2O fluid inclusions within barren veins are remarkably similar to their counterparts in auriferous veins in composition, homogenization temperature, and CO2 effervescence. The most significant difference between the two vein types, and a potential exploration tool, is observed in the CO2-rich inclusions. Tight clustering of first melting temperatures between −57.4 and −56.4 °C and Raman spectroscopy indicate the presence of only CO2 in the barren veins. These results contrast sharply with the −62.5 to −56.0 °C range of first melting temperatures and the presence of H2S indicated by Raman spectroscopy in auriferous veins. Lack of CH4 and H2S gases in the barren CO2-rich inclusions reflects the oxidation state of the fluids, which was too high to permit transport of gold as a reduced complex.
Geochronology of detrital zircons from the Elzevir and Frontenac terranes, Central Metasedimentary Belt, Grenville Province, Ontario
Authors: Sager-Kinsman E. Anne , Parrish R. R.
Published: August 2009

The Central Metasedimentary Belt (CMB) of the Grenville Province contains metasedimentary sequences belonging to a number of distinct tectono-stratigraphic terranes whose depositional ages are poorly known. This study provides information on not only the provenance, but also the maximum age of clastic rocks in two of these terranes, the Elzevir Terrane on the northwest and the Frontenac Terrane to its southeast, adjacent to the Adirondack Mountains of New York.The Flinton Group, a component of the Elzevir Terrane, is a distinctive, mostly clastic, sedimentary sequence that unconformably overlies igneous and metavolcanic rocks of the main part of Elzevir Terrane of the CMB. Analyzed zircons from quartzose metasediments of the Flinton Group are 0–2% discordant and range in age from 1150 to 1335 Ma, with older rounded grains at 1461 ± 5 and 1877 ± 3 Ma. The quartzite was therefore deposited after ca. 1150 Ma, indicating that the Flinton Group is more than 100 Ma younger than the intrusion of the underlying Elzevir batholith. We speculate that 1150–1180 Ma zircons within the Flinton Group were derived from plutons in the Frontenac Terrane to the southeast, implying that the Elzevir and Frontenac terranes were contiguous during Flinton Group deposition. Subsequent metamorphism of the Flinton Group occured between 1150 and 1080 Ma.The high-grade Frontenac Terrane of the CMB lies southeast of Elzevir Terrane, and contains marble associated with pelitic gneiss and quartzite, as well as granitic intrusive rocks; it resembles a metamorphosed continental margin sedimentary sequence. U–Pb analyses of zircons from quartzites from two different localities are generally less than 5% discordant, but show stronger evidence for Grenvillian Pb loss than zircons from the Flinton Group. 207Pb/206Pb ages range from 1493 to 2580 Ma, with one analysis (2% discordant) at 1306 ± 16 Ma, another at 3185 ± 3 Ma, and a cluster of ages between 1745 and 1892 Ma. Detrital zircon ages are, for the most part, distinctly older than in the Flinton Group. The age of this quartzite sequence is tentatively regarded as less than ca. 1300 Ma (based on one grain), but is certainly less than 1500 Ma. It could therefore have been deposited during the same time interval as the 1.2–1.3 Ga metasedimentary and metavolcanic rocks of the Elzevir Terrane. Although Frontenac Terrane experienced metamorphism along with Elzevir Terrane around 1.1 Ga, the principle metamorphic culmination in the Frontenac occurred prior to 1170 Ma.
Tectonic significance of the Late Proterozoic Economy River gneiss, Cobequid Highlands, Avalon Composite Terrane, Nova Scotia
Authors: Doig Ronald , Murphy J. Brendan , Nance R. Damian
Published: August 2009

A 734 ± 2 Ma U–Pb (zircon) age for the Economy River orthogneiss, Coboquid Highlands, Nova Scotia, is interpreted as being representative of a regionally extensive ca. 820–660 Ma event that is recorded in many parts of the Late Proterozoic – Early Cambrian Avalon Composite Terrane and the Gondwanan margin. The geochemistry of the gneiss is consistent with an arc environment. Although the gneiss may represent part of the sialic basement to the terrane, field relationships indicate that some of the basement is significantly older. The date may provide a minimum age for the platformal sedimentary rocks (Gamble Brook Formation) that the orthogneiss intruded and thus help constrain the Late Proterozoic paleogeographic position of Avalon relative to Gondwanaland.
A new specimen of Utatsusaurus (Reptilia: Ichthyosauria) from the Lower Triassic Sulphur Mountain Formation of British Columbia
Authors: Nicholls Elizabeth L. , Brinkman Donald
Published: August 2009

An incomplete skull and mandible of the primitive ichthyosaur Utatsusaurus is described from the Lower Triassic Vega Phroso Member of the Sulphur Mountain Formation of British Columbia. The specimen contributes to our knowledge of the cranial anatomy of the genus, which was previously known primarily from postcranial material, and extends its geographic range to Canada. The presence of an isodont dentition in this primitive genus suggests that isodonty rather than heterodonty may be the primitive character state for the Ichthyosauria.
Late Wenlock – Ludlow (Silurian) graptolite extinction, evolution, and biostratigraphy: perspectives from Arctic Canada
Authors: Lenz Alfred C.
Published: August 2009

Late Wenlock – early Ludlow was a period of profound change in the graptolite world and two "crises" are evident. The most important changeover occurred within the late Wenlock Homerian Stage, during which time Cyrtograptus became extinct, monograptids, while severely reduced, introduced new thecal and and sicular types, and plectograptines underwent a striking diversification. The second, lesser, change coincided with the Wenlock – Ludlow boundary, at which time monograptids reemerged as the dominant taxon group, and plectograptines declined and, shortly thereafter, became extinct.Two species, "Pristiograptus" praedeubeli (Jaeger) and Lobograptus? cornuatus.n.sp., recovered in isolated and uncompressed form, are described and illustrated. The presence of the former species permits the subdivision of the upper Homerian of the Canadian Arctic into two biozones; the lower "Pristiograptus" praedeubeli Biozone and the upper "Pristiograptus" ludensis – "Pristiograptus" sherrardae Biozone. Both species exemplify the novel thecal and sicular morphologies that appeared during the late Homerian and continued into the Ludlow.
The record of jökulhlaups from Summit Lake, northwestern British Columbia
Authors: Mathews William H. , Clague John J.
Published: August 2009

Summit Lake, which is impounded by Salmon Glacier, is the largest self-draining, ice-dammed lake in Canada. Until 1961, it contained few icebergs and was stable, overflowing to the north into me Bowser River valley. The first jökulhlaup occurred in December 1961, after a lengthy period of thinning and retreat of Salmon Glacier, when a subglacial runnel developed in the weakened ice dam, allowing the lake to drain suddenly. This flood and two others in 1965 and 1967 caused major damage to the road system in the Salmon River valley south of the lake. Since 1965, with three exceptions, Summit Lake has drained annually; minor floods along Salmon River in 1966, 1969, and 1973 may record partial drainings of the lake, although other explanations are possible. Jökulhlaups in recent years have been smaller and have occurred earlier in the year than most of the early floods. Rapid water-level fluctuations associated with the annual emptying and refilling of Summit Lake have generated large numbers of icebergs, derived from the Salmon Glacier dam; these icebergs presently choke the surface of the lake. The present jökulhlaup cycle is likely to continue either until the glacier readvances or until it retreats to the point that it no longer forms an effective seal.
The sound and speed of ice-wedge cracking, Arctic Canada
Authors: Mackay J. Ross
Published: August 2009

Rifle-like sounds produced by ice-wedge cracking, although seldom heard, have been reported in the permafrost literature for a century. The sounds, similar to those produced by the rapid cracking of lake ice, indicate a high speed of crack propagation. The speed of ice-wedge crack propagation has been measured at two field sites for the 1966-1989 period. No evidence of rapid crack propagation has been detected at these sites. The fracture patterns of ribs, as seen on vertical crack faces, and the numerous short interacting cracks, as seen in plan view, suggest slow rates of cracking. Enquiries made of many northern residents indicate that rifle-like sounds are uncommon along the mainland coast from the Alaska–Yukon boundary eastward to Coppermine, N.W.T. but are heard more frequently in the Arctic islands. High speeds of crack propagation appear associated with sharp drops in temperature, windblown sites, and long, straight ice wedges. As a preliminary estimate, crack propagation rates exceeding about 200 m/s are necessary to produce rifle-like sounds and accompanying ground tremors.
Analyses des contraintes par méthodes graphiques dans une zone de coulissage : exemple de la région de Matapédia, Gaspésie, Appalaches du Québec
Authors: Trudel Claude , Malo Michel
Published: August 2009

The north-northeast trending Sellarsville and Rafting Ground faults are southeasterly directed Acadian (Devonian) thrusts in the Québec Appalachians. They are located at the western end of the Grand Pabos fault system, a dextral strike-slip fault system that transects Upper Ordovician to Lower Devonian sedimentary rocks in the southern Gaspé Peninsula. The structural analysis of mesoscopic brittle and brittle–ductile shear zones by graphical methods was used to determine the stress field related to these two faults. The attitude of slip lines was calculated when the slickenside striations were not observed on the movement plane. Conjugate faults, Arthaud's method, and Angelier and Mechler's method were used to determine the paleostress. The maximum principal compressive stress σ1, always subhorizontal and striking west-northwest – east-southeast, is perpendicular to the Sellarsville and Rafting Ground faults and was probably the cause of the thrusting motion along the faults. North-northeast-trending regional folds and cleavage could also be related to this same stress. Geological mapping and structural cross sections confirm the southeasterly directed thrust motions, which are well integrated in the Grand Pabos fault system. Sellarsville and Rafting Ground faults with the Restigouche fault may represent a leading contractional imbricate fan in a dextral strike-slip system. [Journal Translation]
Middle Paleozoic tear faulting, basin development, and basement uplift, central Canadian Arctic
Authors: Freitas T. A. de , Mayr U.
Published: August 2009

The Boothia Uplift of the central Canadian Arctic Islands, located some 1200 km west of the Caledonian collision zone, is a "Laramide-type" basement-cored uplift that affected Precambrian crystalline basement and lower Paleozoic carbonate platform sequence. The two major segments of the Boothia Uplift, separated by the east-trending Barrow Strait, had different deformational histories. In the southern segment, uplift of the basement began in Late Silurian time, while in the northern segment, there was subsidence and platform drowning.In the northern segment, a thick sedimentary succession, containing numerous potential detachment surfaces, was involved in Early Devonian deformation. Folding of the cover along northerly trends resulted in the longitudinal infilling of two small, synclinal basins in the hanging wall of the uplift. The type of basin fill was dependent on source proximity and was influenced by contemporaneous flexure of the sedimentary cover. The western basin, the Grove Lake basin, received predominantly terrestrial sediments, and the eastern one, the Sutherland River basin, received mostly marine sediments, including a thick, possibly submarine, synsedimentary breccia that accumulated in response to tilting of partly lithified, carbonate strata. Southward-transported clastic sediments of the basin-fill sequence and contours showing the amount of pre-Emsian erosion suggest that a high-angle tear fault influenced sedimentation in the Grove Lake basin.The areally restricted and variably transported syntectonic clastics of the northern segment are different from coeval clastics of the southern segment. This is attributed to different deformational histories along the uplift and, in particular, to the deformation of a thick, locally anisotropic sedimentary cover sequence in the northern segment.A thick Emsian to early Eifelian carbonate platform sequence onlapped the eroded Boothia Uplift which had acted as a paleohigh for some 10–15 Ma. Early Devonian basement faults appear to have been reactivated as dextral wrench faults during Tertiary time.
The Sylvester Allochthon: upper Paleozoic marginal-basin and island-arc terranes in northern British Columbia
Authors: Nelson JoAnne L.
Published: August 2009

The Sylvester Allochthon is a composite klippe of upper Paleozoic ophiolitic, island-arc, and pericratonic assemblages, which rests directly on the Cassiar terrane, a displaced sliver of Ancestral North America. Each tectonic assemblage occurs at a distinct and consistent structural level within the allochthon. They are assigned, respectively, to the Slide Mountain, Harper Ranch, and Yukon–Tanana terranes. The Sylvester Allochthon provides a view of the structural relationships between these terranes prior to Early Cretaceous – early Tertiary strike-slip dismemberment, as well as possible sedimentological links to late Paleozoic North America. Slide Mountain Terrane assemblages, designated divisions I and II, form the lowest structural panels. Chert – quartz sandstones are interbedded with Lower Mississippian deep-water sediments in division I and ocean-floor basalts and deep-water sediments in division II. They are similar in age and character to sandstones in the autochthonous Earn Group. Division II assemblages represent atypical oceanic crust and upper mantle assemblages. Continuous basalt–sedimentary sequences, well dated by conodont faunas, span Early Mississippian to mid-Permian time. Feeders for the basalts are sills rather than sheeted dyke swarms, suggesting very slow spreading and high(?) sedimentation rates in a marginal-basin setting. These supracrustal sequences are thrust-imbricated with ultramafite–gabbro panels. Division II is in part overlain by a Triassic siliciclastic and limy sedimentary sequence, which resembles the basal Takla Group, Slocan Group, and autochthonous Triassic units. Division III occupies the highest structural levels in the allochthon. With one exception, thrust sheets within it consist of Pennsylvanian to Upper Permian mixed calc-alkaline volcanic and plutonic rocks, chert, tuff, and limestone, assigned to the Harper Ranch Terrane. One panel, assigned to the Yukon–Tanana Terrane, consists of an Early Mississippian quartz diorite pluton with Precambrian inheritance that intrudes older volcanogenic sediments, pyroclastics, limestone, and siliciclastic sediments. Preferred pre-Mesozoic restoration of these terrane elements shows a Harper Ranch arc, built partly on pericratonic Yukon–Tanana and partly on primitive oceanic basement (division III), which is separated from North America by the Slide Mountain marginal basin (divisions I and II).
Unifying aspect- and object-oriented design
Authors: Rajan Hridesh , Sullivan Kevin J.
Published: August 2009

The contribution of this work is the design and evaluation of a programming language model that unifies aspects and classes as they appear in AspectJ-like languages. We show that our model preserves the capabilities of AspectJ-like languages, while improving the conceptual integrity of the language model and the compositionality of modules. The improvement in conceptual integrity is manifested by the reduction of specialized constructs in favor of uniform orthogonal constructs. The enhancement in compositionality is demonstrated by better modularization of integration and higher-order crosscutting concerns.
Learning theory and the re-education of older software engineers
Authors: Baker Ken A.
Published: August 2009

This paper provides an overview of behaviorist, cognitive, and social learning theories, as well as memory and motivation when applied to a paradigm of older software engineers and re-education. While not comprehensive, it does give some insight into the applicability of the different learning theories when applied to the problem of re-educating older software engineers. We find that cognitivist theories, memory and motivation predominantly hold as pedagogical approaches to effectively address this audience.
Conceptualizing and testing formative constructs
Authors: Roberts Nicholas , Thatcher Jason
Published: August 2009

Although abundant advice is available for how to develop and validate multi-item scales based on reflective constructs, scant attention has been directed to how to construct and validate formative constructs. Such advice is important because (1) theory suggests many constructs are formative and (2) recent advances in software render testing models with formative constructs more tractable. In this tutorial, our goal is to enhance understanding of formative constructs at the conceptual, statistical and methodological levels. Specifically, we (1) provide general principles for specifying whether a construct should be conceptually modeled as reflective or formative, (2) discuss the statistical logic behind formative constructs, and (3) illustrate how to model and evaluate formative constructs. In particular, we provide a tutorial in which we test and validate professional reward structure, a formative construct, in two popular structural equation modeling programs: EQS and PLS. We conclude with a summary of guidelines for how to conduct and evaluate research using formative constructs.
Mimivirus and its Virophage
Authors: Claverie Jean-Michel , Abergel Chantal
Published: August 2009

Mimivirus, a virus infecting amoebae of the acanthamoeba genus, is the prototype member of the Mimiviridae, the latest addition to the family of the nucleocytoplasmic large DNA viruses, already including the Poxviridae, the Iridoviridae, the Asfarviridae, and the Phycodnaviridae. Because of the size of its particle—a fiber-covered icosahedral protein capsid 0.75 μm in diameter—Mimivirus was initially mistaken for a parasitic bacterium. Its 1.2-Mb genome sequence encodes more than 900 proteins, many of them associated with functions never before encountered in a virus, such as four aminoacyl-tRNA synthetases. These findings revived the debate about the origin of DNA viruses and their possible role in the emergence of the eukaryotic nucleus. The recent isolation of a new type of satellite virus, called a virophage, associated with a second strain of Mimivirus, confirmed its unique position within the virus world. Post-genomic studies are now in progress, slowly shedding some light on the physiology of the most complex virus isolated to date.
The Challenge of Empirical Research on Business Compliance in Regulatory Capitalism
Authors: Parker Christine , Nielsen Vibeke
Published: August 2009

Regulatory capitalism—a social, political, and economic order characterized by a proliferation of both markets and state and nonstate attempts to regulate markets and business conduct—creates the opportunity for theoretically and politically significant research on compliance. The plural and decentered nature of regulation, and therefore of compliance, in regulatory capitalism creates significant complexity and difficulty for social scientists in the conceptual definition and operationalization of regulatory compliance, however. We survey the different ways in which empirical researchers have studied business compliance with regulation, and their strengths and weaknesses. In doing so, we review and interrogate the literature on regulatory compliance to understand what it is that researchers study when we study business compliance with regulation, and what we might have been missing or assuming.
Cronkhite-Canada Syndrome: Gastric Involvement Diagnosed by MDCT
Authors: Samet Jonathan D. , Horton Karen M. , Fishman Elliot K. , Iacobuzio-Donahue Christine A.
Published: August 2009

Chronkhite-Canada is a rare nonfamilial polyposis syndrome that usually presents as chronic malabsorption in adults. We present a case of a-73-year old woman with chronic gastrointestinal bleeding and malnutrition. On CT imaging she was found to have massive gastric polyps, which on biopsy was most consistent with Cronkhite-Canada syndrome.
Levels of von Willebrand factor antigen and von Willebrand factor cleaving protease (ADAMTS13) activity predict clinical events in chronic heart failure
Authors: Gombos Tímea , Makó Veronika , Cervenak László , Papassotiriou Jana , Kunde Jan , Hársfalvi Jolán , Förhécz Zsolt , Pozsonyi Zoltán , Borgulya Gábor , Jánoskuti Lívia , Prohászka Zoltán
Published: August 2009

Decreased activity of ADAMTS13, the von Willebrand factor (VWF) cleaving protease, was recently reported in cardiovascular diseases and in hepatic failure. Chronic heart failure (CHF) is characterised by abnormalities of left ventricular function accompanied by the failure of the liver and dysregulation of endothelial activation. Therefore, the aim of our study was to measure ADAMTS13 activity in CHF, and determine the prognostic value of VWF and ADAMTS13 on major clinical events in CHF.

ADAMTS13 activity (measured by FRETS-VWF73 substrate) was decreased in CHF (n = 152, left ventricular ejection fraction <45%), and it correlated negatively with B-type natriuretic peptide (BNP) NYHA (New York Heart Association) classes, markers of synthetic capacity of the liver and endothelial dysfunction (all p<0.005). Both, high VWF:Ag levels (hazard ratio [HR] 1.52, 95% confidence interval [CI] 1.189–1.943), and low ADAMTS13/VWF:Ag ratios (HR 0.70, 95% CI 0.58–0.84) independently and significantly predicted short-term (1 year followup) clinical adverse events in heart failure (HF).

Decreased activity of ADAMTS13 with concomitant high VWF:Ag levels is a significant independent predictor of clinical events in CHF. The levels of the two molecules may integrate the impaired synthetic capacity of the liver and the disturbed endothelial regulation and can therefore be a useful tool to predict clinical events in CHF.
Pneumococcal association to platelets is mediated by soluble fibrin and supported by thrombospondin-1
Authors: Heilmann Christine , Rennemeier Claudia , Peters Georg , Hammerschmidt Sven , Niemann Silke , Kehrel Beate E.
Published: August 2009

Platelets and coagulation are involved in bacterial colonisation of the host. Streptocococcus pneumoniae (pneumococcus) are important etiologic agents of respiratory tract infections in humans. The formation of pneumococci-platelet associations may facilitate haematogenous dissemination of pneumococci by providing an adhesive surface on damaged endothelium. However, the formation of platelet-pneumococci associations and the factors involved in this process have not been described so far. The formation of platelet-pneumococci associates was analysed and quantified using flow cytometry. Binding of pneumococci to platelets was significantly increased after activation of platelets with thrombin, while platelet activation by ADP or collagen did not promote formation of platelet-pneumococci associates. In addition to be a platelet agonist, thrombin cleaves fibrinogen, which results in the generation of fibrin. The simultaneous formation of fibrin and activation of platelets was shown to be a prerequisite for a high number of platelet-pneumococci associates. Moreover, exogenously added human thrombospondin-1 (TSP-1) significantly enhanced the association of pneumococci with activated platelets. Soluble fibrin and TSP-1 are key co-factors of platelet-pneumococci-association. Similar results were recently demonstrated for S. aureus-platelet adhesion. Consequently, we hypothesise that the described mechanism of platelet-bacteriaassociation might represent a general and important strategy of Gram-positive bacteria during development of invasive diseases.
A G-quartet oligonucleotide blocks glycoprotein Ib-mediated platelet adhesion and aggregation under flow conditions
Authors: Zhou Zhou , Bernardo Aubrey , Zhu Qiqing , Guan Yongli , Sun Wensheng , Lopez Jose A. , Jing Naijie , Dong Jing-fei
Published: August 2009

Platelets arrest bleeding by adhering to and aggregating on the subendothelium exposed at the site of vessel injury.This process is initiated by the interaction between the subendothelium von Willebrand factor (VWF) and the glycoprotein (GP) Ib-IX-V complex on platelets.However,the same interaction also results in thrombosis at the site of a ruptured atherosclerotic plaque. Reagents regulating the GP Ib-VWF interaction will therefore have direct impact on haemostasis and thrombosis. We have characterised an oligonucleotide G-quartet (T30923) that specifically blocks VWF binding to GP Ibα, theVWF-binding subunit of the GP Ib-IX-V complex.We evaluated the potential interactions of T30923 with GP Ibα and VWF A1 domain by computer simulated molecular dockings, which identified four T30923 docking sites in the β-sheets of the N-terminal region of GP Ibα (E14-D18, S39, D63-S64, and D83-S85). Experimentally,T30923 bound GP Ibα and dose-dependently blocked platelet aggregation induced by ristocetin and thrombin, but not by botrocetin, collagen, TRAP, and ADP. It also blocked shear-induced platelet aggregation and thrombus formation on immobilized VWF under arterial shear stress. These results demonstrate that T30923 may have therapeutic potentials to regulate the GP IbαVWF interaction.
Molecular diversity of anticoagulants from haematophagous animals
Authors: Koh Cho , Kini R. Manjunatha
Published: August 2009

To obtain blood meals, haematophagous animals are armed with potent pharmacological molecules to overcome several of their hosts’ response systems. Among them, a large number of exogenous anticoagulants which target the haemostatic system have been identified and characterised. Studies on these anticoagulants have expanded our knowledge on the blood coagulation system, and provided a valuable source of antithrombotic therapeutic agents. Advances in genomic, transcriptomic, structural and proteomic tools greatly accelerated the discovery and analysis of the exogenous anticoagulants in recent years. The molecular diversity observed in these molecules is huge and is constantly expanding. In this review, we will provide an overview on the structure, function and mechanism of the exogenous anticoagulants from haematophagous animals and rationalise their molecular diversity.