Does the Meguma Terrane Extend into SW England?

The peri-Gondwanan Meguma terrane of southern Nova Scotia, Canada, is the only major lithotectonic element of the northern Appalachian orogen that has no clear correlatives elsewhere in the Appalachians and lacks firm linkages to the Caledonide and Variscan orogens of western and southern Europe. This characteristic is in contrast with its immediate peri-Gondwanan neighbor, Avalonia, which has features in common with portions of Carolinia in the southern Appalachians and has been traced from the Rhenohercynian Zone of southern Britain eastward around the Bohemian Massif to the Carpathians and western Pontides. At issue is the tendency in Europe to assign all peri-Gondwanan terranes lying outboard of the Rheic suture to Avalonia, characterized by relatively juvenile basement and detrital zircon ages that include Mesoproterozoic populations, and those inboard of the suture to Cadomia, characterized by a more evolved basement and detrital zircon ages that match Paleoproterozoic and older sources in the West African craton.    Although the unexposed basements of Avalonia and Meguma are thought to be isotopically very similar, the Meguma sedimentary cover contains scarce Mesoproterozoic zircon and is dominated instead by Neoproterozoic and Paleoproterozoic populations like those of Cadomia. Hence, felsic magma produced by crustal melting in the Meguma terrane (e.g. the ca. 370 Ma South Mountain Batholith) is isotopically more juvenile (eNd = –5 to –1, TDM = 1.3 Ga) than the rocks it intruded (eNd= –12 to –7, TDM = 1.7 Ga). By contrast, felsic magma produced by crustal melting in Avalonia (eNd = –1 to +6, TDM = 0.7–1.2 Ga) is isotopically similar to its host rocks (eNd = –3 to +4, TDM = 0.9–1.4).    The isotopic relationship shown by the Meguma terrane has also been recognized in the South Portuguese Zone of southern Spain, which is traditionally assigned to Avalonia. However, the Sierra Norte Batholith of the South Portuguese Zone (ca. 330 Ma; eNd = +1 to –3, TDM = 0.9–1.2 Ga) is on average more juvenile than the Late Devonian host rocks (eNd = –5 to –11) it intruded, suggesting instead an extension of the Meguma terrane into Europe. Available data for the Cornubian Batholith of SW England (ca. 275–295 Ma; eNd = –4 to –7, TDM = 1.3–1.8 Ga) and the Devonian–Carboniferous metasedimentary rocks it intruded (eNd = –8 to –11) suggests this may also be true of that part of the southern Britain (Rhenohercynian Zone) with which the South Portuguese Zone is traditionally correlated.SOMMAIRELe terrane péri-gondwanien de Meguma en Nouvelle-Écosse au Canada, est le seul grand élément lithotectonique de l’orogène des Appalaches du Nord qui n’ait pas de correspondant avéré ailleurs dans les Appalaches et qui ne montre aucun lien sûr avec les orogènes calédonienne et varisque de l’ouest et du sud de l’Europe.  Cette situation contraste avec celle de son voisin péri-gondwanien immédiat, l’Avalonie, qui partage certaines caractéristiques avec des portions de Carolinia des Appalaches du sud et qui a été suivi à partir de la zone rhénohercynienne dans le sud de la Grande-Bretagne vers l’est autour du massif bohémien jusqu’aux Carpates et l’ouest de la chaîne pontique.  Ce qui est en question ici c’est la tendance en Europe à assigner l’Avalonie à tous les terranes péri-gondwaniens situés à l’extérieur de la suture rhéïque lesquels sont caractérisés par un socle relativement juvénile et des âges de zircons détritiques qui comportent des populations mésoprotérozoïques, et ceux situés à l’intérieur de la suture à Cadomia, lesquels sont caractérisés par un socle plus évolué et des âges de zircons détritiques qui correspondent à des sources du craton ouest africain paléoprotérozoïques et plus anciennes.     Bien que l’on estime que les socles non-exposés des terranes d’Avalonie et de Meguma soient très similaires isotopiquement, le couvert sédimentaire de Meguma ne renferme que de rares zircons mésoprotérozoïques, et ce sont plutôt les populations de zircons néoprotérozoïques et paléoprotérozoïques qui dominent, comme c’est le cas pour Cadomia.  Il en ressort que le magma felsique produit par la fusion de croûte dans le terrane de Meguma (par ex. le batholite de South Mountain de 370 Ma env.) est isotopiquement plus jeune (eNd = –5 à –1, TDM = 1.3 Ga) que les roches qu’il recoupe (eNd= –12 à –7, TDM = 1.7 Ga).  Par opposition, le magma felsique produit par la fusion de la croûte dans le terrane d’Avalonie (eNd = –1 à +6, TDM = 0.7–1.2 Ga) est isotopiquement similaire aux roches de son encaissant (eNd = –3 à +4, TDM = 0.9–1.4).     Le profil isotopique du terrane de Meguma, traditionnellement assignée à l’Avalonie,  a aussi été détecté dans la Zone sud-portugaise du sud de l’Espagne.  Cependant, le batholite de Sierra Norte de la Zone sud-portugaise (ca. 330 Ma; eNd = +1 à –3, TDM = 0.9–1.2 Ga) est en moyenne plus jeune que l’encaissant du Dévonien moyen (eNd = –5 à –11) qu’il recoupe, ce qui permet de penser à une extension du terrane de Meguma en Europe.  Les données disponibles du batholite de Cornubian dans le S-O de l’Angleterre (ca. 275–295 Ma; eNd = –4 à –7, TDM = 1.3–1.8 Ga) et des roches métasédimentaires dévono-carbonifères qu’il recoupe (eNd = –8 to –11) permet de penser qu’il pourrait en être de même de cette portion du sud de la Grande-Bretagne (Zone rhénohercynienne) avec laquelle la Zone sud-portugaise est traditionnellement corrélée

40Ar/39Ar phlogopite geochronology of lamprophyre dykes in Cornwall, UK: new age constraints on Early Permian post-collisional magmatism in the Rhenohercynian Zone, SW England

Journal of the Geological Society (2015), http://jgs.lyellcollection.org/content/early/2015/06/03/jgs2014-151. Copyright © Geological Society of London 2015The spatial and temporal association of post-collisional granites and lamprophyre dykes is a common but enigmatic relationship in many orogenic belts, including the Variscan orogenic belt of SW England. The geology of SW England has long been interpreted to reflect orogenic processes associated with the closure of the Rheic Ocean and the formation of Pangaea. The SW England peninsula is composed largely of Early Devonian to Carboniferous volcano-sedimentary successions deposited in synrift and subsequent syncollisional basins that underwent deformation and low-grade regional metamorphism during the Variscan orogeny. Voluminous Early Permian granitic magmatism (Cornubian Batholith) is considered to be broadly coeval with the emplacement of lamprophyric dykes and lamprophyric and basaltic lava flows, largely on the basis of geochronological data from lamprophyric lavas in Devon. Although published geochronological data for Cornish lamprophyre dykes are consistent with this interpretation, these data are limited largely to imprecise K–Ar whole-rock and biotite analyses, hindering the understanding of the processes responsible for their genesis and their relationship to granitic magmatism and regional Variscan tectonics. 40Ar/39Ar geochronological data for four previously undated lamprophyre dykes from Cornwall, combined with published data, suggest that lamprophyre magmatism occurred between c. 293.6 and c. 285.4 Ma, supporting previous inferences that their emplacement was coeval with the Cornubian Batholith. These data provide insights into (1) the relative timing between the lamprophyres and basalts, the Cornubian batholith and post-collisional magmatism elsewhere in the European Variscides, and (2) the post-collisional processes responsible for the generation and emplacement of lamprophyres, basalts and granitoids.NSERC (Canada) Discovery grant

Effect of roughness formulation on the performance of a coupled wave, hydrodynamic, and sediment transport model

This paper is not subject to U.S. copyright. The definitive version was published in Ocean Modelling 33 (2010): 299-313, doi:10.1016/j.ocemod.2010.03.003.A variety of algorithms are available for parameterizing the hydrodynamic bottom roughness associated with grain size, saltation, bedforms, and wave–current interaction in coastal ocean models. These parameterizations give rise to spatially and temporally variable bottom-drag coefficients that ostensibly provide better representations of physical processes than uniform and constant coefficients. However, few studies have been performed to determine whether improved representation of these variable bottom roughness components translates into measurable improvements in model skill. We test the hypothesis that improved representation of variable bottom roughness improves performance with respect to near-bed circulation, bottom stresses, or turbulence dissipation. The inner shelf south of Martha’s Vineyard, Massachusetts, is the site of sorted grain-size features which exhibit sharp alongshore variations in grain size and ripple geometry over gentle bathymetric relief; this area provides a suitable testing ground for roughness parameterizations. We first establish the skill of a nested regional model for currents, waves, stresses, and turbulent quantities using a uniform and constant roughness; we then gauge model skill with various parameterization of roughness, which account for the influence of the wave-boundary layer, grain size, saltation, and rippled bedforms. We find that commonly used representations of ripple-induced roughness, when combined with a wave–current interaction routine, do not significantly improve skill for circulation, and significantly decrease skill with respect to stresses and turbulence dissipation. Ripple orientation with respect to dominant currents and ripple shape may be responsible for complicating a straightforward estimate of the roughness contribution from ripples. In addition, sediment-induced stratification may be responsible for lower stresses than predicted by the wave–current interaction model.Funding was provided through the Office of Naval Research Ripples DRI and U.S. Geological Survey Coastal and Marine Geology Program

A review of hyperfibrinolysis in cats and dogs

The fibrinolytic system is activated concurrently with coagulation; it regulates haemostasis and prevents thrombosis by restricting clot formation to the area of vascular injury and dismantling the clot as healing occurs. Dysregulation of the fibrinolytic system, which results in hyperfibrinolysis, may manifest as clinically important haemorrhage. Hyperfibrinolysis occurs in cats and dogs secondary to a variety of congenital and acquired disorders. Acquired disorders associated with hyperfibrinolysis, such as trauma, cavitary effusions, liver disease and Angiostrongylus vasorum infection, are commonly encountered in primary care practice. In addition, delayed haemorrhage reported in greyhounds following trauma and routine surgical procedures has been attributed to a hyperfibrinolytic disorder, although this has yet to be characterised. The diagnosis of hyperfibrinolysis is challenging and, until recently, has relied on techniques that are not readily available outside referral hospitals. With the recent development of point‐of‐care viscoelastic techniques, assessment of fibrinolysis is now possible in referral practice. This will provide the opportunity to target haemorrhage due to hyperfibrinolysis with antifibrinolytic drugs and thereby reduce associated morbidity and mortality. The fibrinolytic system and the conditions associated with increased fibrinolytic activity in cats and dogs are the focus of this review article. In addition, laboratory and point‐of‐care techniques for assessing hyperfibrinolysis and antifibrinolytic treatment for patients with haemorrhage are reviewed

Antimicrobial management and appropriateness of treatment of urinary tract infection in general practice in Ireland

<p>Abstract</p> <p>Background</p> <p>Urinary tract infections (UTIs) are the second most common bacterial infections in general practice and a frequent indication for prescription of antimicrobials. Increasing concern about the association between the use of antimicrobials and acquired antimicrobial resistance has highlighted the need for rational pharmacotherapy of common infections in general practice.</p> <p>Methods</p> <p>Management of urinary tract infections in general practice was studied prospectively over 8 weeks. Patients presenting with suspected UTI submitted a urine sample and were enrolled with an opt-out methodology. Data were collected on demographic variables, previous antimicrobial use and urine samples. Appropriateness of different treatment scenarios was assessed by comparing treatment with the laboratory report of the urine sample.</p> <p>Results</p> <p>A total of 22 practices participated in the study and included 866 patients. Bacteriuria was established for 21% of the patients, pyuria without bacteriuria for 9% and 70% showed no laboratory evidence of UTI. An antimicrobial agent was prescribed to 56% (481) of the patients, of whom 33% had an isolate, 11% with pyuria only and 56% without laboratory evidence of UTI. When taking all patients into account, 14% patients had an isolate identified and were prescribed an antimicrobial to which the isolate was susceptible. The agents most commonly prescribed for UTI were co-amoxyclav (33%), trimethoprim (26%) and fluoroquinolones (17%). Variation between practices in antimicrobial prescribing as well as in their preference for certain antimicrobials, was observed. Treatment as prescribed by the GP was interpreted as appropriate for 55% of the patients. Three different treatment scenarios were simulated, i.e. if all patients who received an antimicrobial were treated with nitrofurantoin, trimethoprim or ciprofloxacin only. Treatment as prescribed by the GP was no more effective than treatment with nitrofurantoin for all patients given an antimicrobial or treatment with ciprofloxacin in all patients. Prescribing cost was lower for nitrofurantoin. Empirical treatment of all patients with trimethoprim only was less effective due to the higher resistance levels.</p> <p>Conclusions</p> <p>There appears to be considerable scope to reduce the frequency and increase the quality of antimicrobial prescribing for patients with suspected UTI.</p

⁴⁰Ar/³⁹Ar phlogopite geochronology of lamprophyre dykes in Cornwall, UK: new age constraints on Early Permian post-collisional magmatism in the Rhenohercynian Zone, SW England

<p>The spatial and temporal association of post-collisional granites and lamprophyre dykes is a common but enigmatic relationship in many orogenic belts, including the Variscan orogenic belt of SW England. The geology of SW England has long been interpreted to reflect orogenic processes associated with the closure of the Rheic Ocean and the formation of Pangaea. The SW England peninsula is composed largely of Early Devonian to Carboniferous volcano-sedimentary successions deposited in synrift and subsequent syncollisional basins that underwent deformation and low-grade regional metamorphism during the Variscan orogeny. Voluminous Early Permian granitic magmatism (Cornubian Batholith) is considered to be broadly coeval with the emplacement of lamprophyric dykes and lamprophyric and basaltic lava flows, largely on the basis of geochronological data from lamprophyric lavas in Devon. Although published geochronological data for Cornish lamprophyre dykes are consistent with this interpretation, these data are limited largely to imprecise K–Ar whole-rock and biotite analyses, hindering the understanding of the processes responsible for their genesis and their relationship to granitic magmatism and regional Variscan tectonics. ⁴⁰Ar/³⁹Ar geochronological data for four previously undated lamprophyre dykes from Cornwall, combined with published data, suggest that lamprophyre magmatism occurred between <em>c</em>. 293.6 and <em>c</em>. 285.4 Ma, supporting previous inferences that their emplacement was coeval with the Cornubian Batholith. These data provide insights into (1) the relative timing between the lamprophyres and basalts, the Cornubian batholith and post-collisional magmatism elsewhere in the European Variscides, and (2) the post-collisional processes responsible for the generation and emplacement of lamprophyres, basalts and granitoids. </p

40

Journal of the Geological Society (2015), http://jgs.lyellcollection.org/content/early/2015/06/03/jgs2014-151. Copyright © Geological Society of London 2015The spatial and temporal association of post-collisional granites and lamprophyre dykes is a common but enigmatic relationship in many orogenic belts, including the Variscan orogenic belt of SW England. The geology of SW England has long been interpreted to reflect orogenic processes associated with the closure of the Rheic Ocean and the formation of Pangaea. The SW England peninsula is composed largely of Early Devonian to Carboniferous volcano-sedimentary successions deposited in synrift and subsequent syncollisional basins that underwent deformation and low-grade regional metamorphism during the Variscan orogeny. Voluminous Early Permian granitic magmatism (Cornubian Batholith) is considered to be broadly coeval with the emplacement of lamprophyric dykes and lamprophyric and basaltic lava flows, largely on the basis of geochronological data from lamprophyric lavas in Devon. Although published geochronological data for Cornish lamprophyre dykes are consistent with this interpretation, these data are limited largely to imprecise K–Ar whole-rock and biotite analyses, hindering the understanding of the processes responsible for their genesis and their relationship to granitic magmatism and regional Variscan tectonics. 40Ar/39Ar geochronological data for four previously undated lamprophyre dykes from Cornwall, combined with published data, suggest that lamprophyre magmatism occurred between c. 293.6 and c. 285.4 Ma, supporting previous inferences that their emplacement was coeval with the Cornubian Batholith. These data provide insights into (1) the relative timing between the lamprophyres and basalts, the Cornubian batholith and post-collisional magmatism elsewhere in the European Variscides, and (2) the post-collisional processes responsible for the generation and emplacement of lamprophyres, basalts and granitoids.NSERC (Canada) Discovery grant

Variation in olfactory neuron repertoires is genetically controlled and environmentally modulated

The mouse olfactory sensory neuron (OSN) repertoire is composed of 10 million cells and each expresses one olfactory receptor (OR) gene from a pool of over 1000. Thus, the nose is sub-stratified into more than a thousand OSN subtypes. Here, we employ and validate an RNA-sequencing-based method to quantify the abundance of all OSN subtypes in parallel, and investigate the genetic and environmental factors that contribute to neuronal diversity. We find that the OSN subtype distribution is stereotyped in genetically identical mice, but varies extensively between different strains. Further, we identify cis-acting genetic variation as the greatest component influencing OSN composition and demonstrate independence from OR function. However, we show that olfactory stimulation with particular odorants results in modulation of dozens of OSN subtypes in a subtle but reproducible, specific and time-dependent manner. Together, these mechanisms generate a highly individualized olfactory sensory system by promoting neuronal diversity6FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP09/00473-0; 2015/50371-