1,134 research outputs found

    Dispersed weathering products of carbonate rock: Features and formation conditions from the construction's point of view (by the example of Kazan, Russia)

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    Geological conditions of the Kazan city area are typical for East European Platform: alluvial sandy-clay sediments overlay the eroded surface of Permian, mainly carbonate section. Dispersed products of carbonate rock weathering appear at interfacial contact of these two associations. They can be attributed to a group of problem soils, because of their considerable inhomogeneity, irregular variability of physical-mechanical properties, internal instability, susceptibility to suffosion and solubility. All of these properties suggest the difficulties in implementation of field tests and in sampling, as well as in measurement of physical-mechanical properties in laboratory conditions. This paper presents laboratory test results on dispersed products of carbonate rock weathering sampled on the Kazan city area. A series of triaxial compression tests was conducted to understand the mechanical properties of these samples. The spatio-temporal model of carbonate weathering crust formation process is proposed. The recommendations are made for organization the engineering- geological research in the regions, where dispersed products of carbonate rock weathering. © 2013 Taylor & Francis Group, London

    EPR and SEM study of organo-mineral associations in lower permian evaporite dolomites

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    Lower Permian (280 to 300 Ma) evaporite dolomite rocks from the western part of the East European platform were studied by optical microscopy, scanning electron microscopy with microprobe analysis, and X-band electron paramagnetic resonance (EPR). Microscopic studies showed that many dolomite grains consist of an aggregation of submicron dolomite crystals (0.2-2 μm) as a spheroidal nucleus which is overgrown by a larger dolomite rhombohedron (5-20 μm). The EPR spectrum of a raw rock sample is mainly determined by thermally unstable radiation centers and Mn 2+ ions substituted at Ca and Mg sites in the dolomite crystal structure. The presence of dispersed organic matter at low concentrations was revealed from the backscattered electron images with a microprobe analysis of carbon-enriched areas on cleaved surfaces and the registration of the carbon-centered free organic radical signal in EPR spectra of heat-treated samples. A model of two successive growing stages for dolomite grains is suggested: the dolomite (or dolomite precursor) nucleation and aggregation in the colloidal stage to form suspended organo-mineral particles before the gravitational settling, and early diagenetic overgrowth at lower temperature and more stable environment of the marine bottom to form a dolomite rhombohedron. The observation of both growing stages for dolomite grains indicates that there was no recrystallization in the later stages of the rock history. © Springer-Verlag 2009

    Features of reef formation in the evlan time of upper devonian sediments by electron paramagnetic resonance

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    © SGEM2017. All Rights Reserved. Investigation of the paramagnetic properties of core samples from the section of the reference well was performed on the basis of a representative sample (97 samples) by electron paramagnetic resonance (EPR) for mineral associations of the Evlan horizon of the Upper Devonian deposits of the Volga-Ural region of the Republic of Tatarstan. Within the Volga-Ural region, reef formation dates back to the late Frasnian and has developed to the maximum extent in the Voronezh, Evlan and Liven times. The deposition of the Voronezh horizon begins with a series of limestone, intensely dolomitized and recrystallized, where oxide iron is present in the secondary calcite was determined from the EPR spectra. The Evlan sequence of deposits, according to the EPR data, begins with an anhydrite of dolomite interlayer, above which limestone rocks with various degrees of dolomites (1601 m - 1597.4 m) were deposited. At the same time, the position of this interlayer characterizes the presence of a reservoir, the tops of which correspond to a mark of 1599.1 m. According to the results of EPR studies of the C 600 carbonized syngenetic radical, it is established that its concentration in the calcareous section of the Voronezh deposit section is more than 1.5 times the concentration in the Evlan deposits. Upwards in the section of the Evlan deposits, regressive shallowing of the basin is observed in the calcareous section and a change in the carbonate to sulfate sedimentation and the release of sediments onto the surface occurs. These processes led to a frequent change of the Eh-pH conditions already at the stage of early diagenesis. The appearance of secondary calcite and dolomitization of limestone allows us to distinguish the stages of alkaline diagenesis

    Red paleosols in the key sections of the Middle and Upper Permian of the Kazan Volga region and their paleoclimatic significance

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    © 2015, Pleiades Publishing, Ltd. This paper presents the preliminary results of investigations of carbonate nodules from red paleosols of the reference sections of the Middle and Upper Permian of the Kazan Volga region. The main genetic types of paleosols are calcic gleysols and gleyed vertisols, the pedogenic nodules are composed of dolomite and calcite. Scanning electron microscopy and spectroscopic and isotopic methods of analysis show that the nodules retained their original mineral composition and were formed with the participation of soil microorganisms under conditions of contrasting seasonality in an arid climate. In the vicinity of the Kiama–Illawarra paleomagnetic boundary, the Urzhumian paleosols show a transition in the composition of pedogenic nodules from dolomite to calcite. It is suggested that this transition was caused by the humidization of climate, which is supported by lithological and isotopic data

    Suitability of PSA-detected localised prostate cancers for focal therapy: Experience from the ProtecT study

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    This article is available through a Creative Commons Attribution-NonCommercial-Share Alike 3.0 Unported License. Copyright @ 2011 Cancer Research UK.Background: Contemporary screening for prostate cancer frequently identifies small volume, low-grade lesions. Some clinicians have advocated focal prostatic ablation as an alternative to more aggressive interventions to manage these lesions. To identify which patients might benefit from focal ablative techniques, we analysed the surgical specimens of a large sample of population-detected men undergoing radical prostatectomy as part of a randomised clinical trial. Methods: Surgical specimens from 525 men who underwent prostatectomy within the ProtecT study were analysed to determine tumour volume, location and grade. These findings were compared with information available in the biopsy specimen to examine whether focal therapy could be provided appropriately. Results: Solitary cancers were found in prostatectomy specimens from 19% (100 out of 525) of men. In addition, 73 out of 425 (17%) men had multiple cancers with a solitary significant tumour focus. Thus, 173 out of 525 (33%) men had tumours potentially suitable for focal therapy. The majority of these were small, well-differentiated lesions that appeared to be pathologically insignificant (38–66%). Criteria used to select patients for focal prostatic ablation underestimated the cancer's significance in 26% (34 out of 130) of men and resulted in overtreatment in more than half. Only 18% (24 out of 130) of men presumed eligible for focal therapy, actually had significant solitary lesions. Conclusion: Focal therapy appears inappropriate for the majority of men presenting with prostate-specific antigen-detected localised prostate cancer. Unifocal prostate cancers suitable for focal ablation are difficult to identify pre-operatively using biopsy alone. Most lesions meeting criteria for focal ablation were either more aggressive than expected or posed little threat of progression.National Institute for Health Researc

    A Clinician\u27s Guide to Next Generation Imaging in Patients With Advanced Prostate Cancer (RADAR III).

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    PURPOSE: The advanced prostate cancer therapeutic landscape has changed dramatically in the last several years, resulting in improved overall survival of patients with castration naïve and castration resistant disease. The evolution and development of novel next generation imaging techniques will affect diagnostic and therapeutic decision making. Clinicians must navigate when and which next generation imaging techniques to use and how to adjust treatment strategies based on the results, often in the absence of correlative therapeutic data. Therefore, guidance is needed based on best available information and current clinical experience. MATERIALS AND METHODS: The RADAR (Radiographic Assessments for Detection of Advanced Recurrence) III Group convened to offer guidance on the use of next generation imaging to stage prostate cancer based on available data and clinical experience. The group also discussed the potential impact of next generation imaging on treatment options based on earlier detection of disease. RESULTS: The group unanimously agreed that progression to metastatic disease is a seminal event for patient treatment. Next generation imaging techniques are able to detect previously undetectable metastases, which could redefine the phases of prostate cancer progression. Thus, earlier systemic or locally directed treatment may positively alter patient outcomes. CONCLUSIONS: The RADAR III Group recommends next generation imaging techniques in select patients in whom disease progression is suspected based on laboratory (biomarker) values, comorbidities and symptoms. Currently 18F-fluciclovine and 68Ga prostate specific membrane antigen positron emission tomography/computerized tomography are the next generation imaging agents with a favorable combination of availability, specificity and sensitivity. There is ongoing research of additional next generation imaging technologies, which may offer improved diagnostic accuracy and therapeutic options. As next generation imaging techniques evolve and presumably result in improved global accessibility, clinician ability to detect micrometastases may be enhanced for decision making and patient outcomes

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Standalone vertex finding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

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    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

    Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

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    A measurement of the production cross-section for top quark pairs(\ttbar) in pppp collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron ee or muon μ\mu) with large missing transverse energy and at least four jets, and dilepton (eeee, μμ\mu\mu or eμe\mu) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.912.2 \pm 3.9 events and 2.5±0.62.5 \pm 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde
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