Publications by authors named "Klassen N"

Background: Healthcare resource use for atrial fibrillation (AF) is high, but it may not be equivalent across all patients. We examined whether sex differences exist for AF high-cost users (HCUs), who account for the top 10% of total acute care costs.

Methods: All patients aged ≥ 20 years who presented to the emergency department (ED) or were hospitalized with AF were identified in Alberta, Canada, between 2011 and 2015.

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Visual processing is altered for stimuli located near the hands, in what is termed peri-hand space, but it is unclear whether peri-hand effects are stable across the lifespan. To investigate this, adults and 5- to 8-year-old children completed a naturalistic visual search task on a touchscreen monitor while wearing eye-tracking glasses. Upon recognizing a previously specified target image in a 12-image array, they released a pushbutton with their left index finger in order to reach out and touch the target.

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Background: Data are limited data on the prevalence of cardiovascular disease (CVD) and multimorbidity in contemporary cohorts of high-cost users (HCUs) in Canada.We examined the following: (i) the prevalence of CVD, with a comparison of total healthcare costs among HCUs with vs without CVD; (ii) the contribution of other comorbidities to costs among HCUs with CVD; and (iii) the trajectory of healthcare costs in the years before and after becoming an HCU.

Methods: The study included adult Alberta patients in the Canadian Institutes of Health Research/Canadian Institute for Health Information Dynamic Cohort of Complex, High System Users from 2011-2012 through 2014-2015.

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Cadmium (Cd) is a heavy metal that can cause a variety of adverse effects on human health, including cancer. Wheat comprises approximately 20% of the human diet worldwide; therefore, reducing the concentrations of Cd in wheat grain will have significant impacts on the intake of Cd in food products. The tests for measuring the Cd content in grain are costly, and the content is affected significantly by soil pH.

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Four genomic regions on chromosomes 4A, 6A, 7B, and 7D were discovered, each with multiple tightly linked QTL (QTL clusters) associated with two to three yield components. The 7D QTL cluster was associated with grain yield, fertile spikelet number per spike, thousand kernel weight, and heading date. It was located in the flanking region of FT-D1, a homolog gene of Arabidopsis FLOWERING LOCUS T, a major gene that regulates wheat flowering.

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Peri-hand space is the area surrounding the hand. Objects within this space may be subject to increased visuospatial perception, increased attentional prioritization, and slower attentional disengagement compared to more distal objects. This may result from kinesthetic and visual feedback about the location of the hand that projects from the reach and grasp networks of the dorsal visual stream back to occipital visual areas, which in turn, refines cortical visual processing that can subsequently guide skilled motor actions.

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Selecting high-yielding wheat cultivars with more productive tillers per unit area (PTN) combined with more fertile spikelets per spike (fSNS) is difficult. QTL mapping of these traits may aid understanding of this bottleneck and accelerate precision breeding for high yield via marker-assisted selection. PTN and fSNS were assessed in four to five trials from 2015 to 2017 in a doubled haploid population derived from two high-yielding cultivars "UI Platinum" and "SY Capstone.

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Fusarium head blight (FHB) is a destructive disease of wheat in humid and semihumid areas of the world. It has emerged in the Pacific Northwest (PNW) in recent years because of changing climate and crop rotation practices. Our objectives in the present study were to identify and characterize quantitative trait loci (QTL) associated with FHB resistance in spring wheat lines developed in the PNW and the International Maize and Wheat Improvement Center.

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The main focus of this paper is the description of qualitatively new facilities for diagnostics of biological and medical objects and medical therapy obtained by applications of nanocrystalline scintillators. These facilities are based on abilities of nanoscintillators to selective conjugation with various biomolecular objects and noticeable variations of their atomic structures, X-ray diffraction (XRD) patterns, and light-emission characteristics induced by modifications of conditions on their external surfaces. Experimental results presented in this paper provide development of detection in vivo just inside a living organism of various viruses, cancer cells, and other pathological macromolecules by means of scanning X-ray diffractometry of nanoparticles introduced into the body.

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The authors of a recent paper (Claridge Mackonis et al 2007 Phys. Med. Biol.

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Spectroscopic, laser, and chi((3)) nonlinear optical properties of tetragonal PbWO(4), NaY(WO(4))(2), CaWO(4), and monoclinic CdWO(4) and ZnWO(4) were investigated. Particular attention was paid to Nd(3+)-doped and undoped PbWO(4) and NaY(WO(4))(2) crystals. Their absorption and luminescence intensity characteristics, including the peak cross sections of induced transitions, were determined.

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Background: Canada is a major recipient of foreign-trained health professionals, notably physicians from South Africa and other sub-Saharan African countries. Nurse migration from these countries, while comparatively small, is rising. African countries, meanwhile, have a critical shortage of professionals and a disproportionate burden of disease.

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Absorbed doses determined with a sealed water calorimeter operated at 4 degrees C are compared with the results obtained using ionization chambers and the IAEA TRS-398 code of practice in a 10 MV photon beam (TPR(20,10) = 0.734) and a 175 MeV proton beam (at a depth corresponding to the residual range, R(res) = 14.7 cm).

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The energy dependence of alanine/EPR dosimetry for 8, 12, 18 and 22 MeV clinical electron beams was investigated by experiment and by Monte Carlo simulations. Alanine pellets in a waterproof holder were irradiated in a water phantom using an Elekta Precise linear accelerator. The dose rates at the reference point were determined following the TG-51 protocol using an NACP-02 parallel-plate chamber calibrated in a (60)Co beam.

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As part of a collaborative project between the National Research Council of Canada (NRC) and the Swiss Federal Office of Metrology and Accreditation (METAS), a sealed water calorimeter was built at NRC and transferred to METAS. The calorimeter is operated at 4 degrees C and uses two thermistor probes in a sealed glass vessel containing high-purity water to measure the radiation-induced temperature rise. The various correction factors have been evaluated and the estimated standard uncertainty on the absorbed dose to water is 0.

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The energy dependence of alanine/EPR dosimetry, in terms of absorbed dose-to-water for clinical 6, 10, 25 MV x-rays and 60Co gamma-rays was investigated by measurements and Monte Carlo (MC) calculations. The dose rates were traceable to the NRC primary standard for absorbed dose, a sealed water calorimetry. The electron paramagnetic resonance (EPR) spectra of irradiated pellets were measured using a Bruker EMX 081 EPR spectrometer.

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In a recent publication, we used a reaction model (model III) to calculate the heat defect for the irradiation of aqueous solutions with ionizing radiation at 21 °C. Subsequent work has revealed that the literature value used for one of the rate constants in the model was incorrect. A revised model (model IIIR) incorporates the correct rate constant for 21 °C.

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A calibration of the Fricke dosimeter is a measurement of epsilon G(Fe3+). Although G(Fe3+) is expected to be approximately energy independent for all low-LET radiation, existing data are not adequate to rule out the possibility of changes of a few per cent with beam quality. When a high-precision Fricke dosimeter, which has been calibrated for one particular low-LET beam quality, is used to measure the absorbed dose for another low-LET beam quality, the accuracy of the absorbed dose measurement is limited by the uncertainty in the value of G(Fe3+).

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GafChromic MD-55 is a fairly new, thin film dosimeter that develops a blue color (lambda max = 676 nm) when irradiated with ionizing radiation. The increase in absorbance is roughly proportional to the absorbed dose. In this study, GafChromic MD-55 was irradiated with 60Co gamma rays.

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Water Calorimetry: The Heat Defect.

J Res Natl Inst Stand Technol

January 1997

Domen developed a sealed water calorimeter at NIST to measure absorbed dose to water from ionizing radiation. This calorimeter exhibited anomalous behavior using water saturated with gas mixtures of H and O. Using computer simulations of the radiolysis of water, we show that the observed behavior can be explained if, in the gas mixtures, the amount-of-substance of H and of O differed significantly from 50 %.

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A 36-year-old woman in the second trimester of pregnancy underwent emergent operative repair of a traumatic aortic disruption caused by a motor vehicle accident. Left atrial-to-femoral artery bypass was used to maintain fetal circulation during the cross-clamp period. Her healthy, full-term child was subsequently delivered 3 months later by normal vaginal delivery.

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Calorimetry has a long history as a technique for establishing the absorbed dose, and graphite calorimetry has often been used to establish absorbed dose standards for use in radiation therapy. However, a conversion process is necessary to convert from dose to graphite to dose to water, which is the quantity of clinical interest. In order to more directly measure the dose to water, considerable effort has been devoted in the last fifteen years to the development of water calorimetry.

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This in vitro study was undertaken to determine if ultrahigh dose rates could improve the radiation response of human tumors. Two cell lines, human glioma (U-87 MG), which is radioresistant, and human melanoma (HT-144), which is radiosensitive, were irradiated at ultrahigh and high dose rates under aerobic and anoxic conditions to determine if their oxygen enhancement ratios are modified by dose rate. In fact, the survival curves, and hence the oxygen enhancement ratios, were found to be independent of the dose rate.

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Suspensions of rat thymocytes were given 0.09-100 Gy using 60Co gamma-rays. The radiation-induced changes in the thymocytes were examined from minutes to hours post-irradiation using electron microscopy, agarose gel electrophoresis, staining and Coulter Counter sizing.

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Considerable effort has been devoted to measuring the absorbed dose to water using water calorimetry. Most of these efforts have been hampered by a lack of adequate knowledge of the heat defect of water. We argue that there is now sufficient information to establish with considerable confidence the heat defect of high-purity water containing various dissolved gases.

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