513 research outputs found

    Assessment of Tornado Alerting Performance for Canada

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    The Northern Tornadoes Project (NTP) completed a first independent assessment of national tornado warning alerting (watches and warnings) in Canada covering the 2019–2021 period. The NTP undertook this study in the spirit of open data, understanding tornado warning issues unique to this country, and improving tornado warning performance. Utilizing the NTP tornado event database for verification, tornado alerts were reviewed for accuracy and timeliness. For the 250 tornadoes that occurred during the study period–and using a definition of what constitutes a warning ‘hit’ developed for the study–the standard 2 × 2 contingency table scores were Probability of Detection = 0.23, FAR = 0.78, and CSI = 0.13. Over 70% of tornadoes had no tornado warning, including 35 EF2 tornadoes. The tornado warning results were compared with US National Weather Service tornado warning scores for the US and US states along the southern Canadian border to provide context. NTP also developed a ‘report card’ aimed at public and media consumption that took into consideration Environment and Climate Change Canada’s national performance targets for tornado warning Probability of Detection (POD) and lead time as well as tornado watch issuance. Using weighted scores for these criteria, NTP assigned a total score of 33.3/100, indicating significant room for improvement. A follow-up assessment was conducted for the 2022 tornado season in Canada following the same established procedures. It was found that the number of both tornado watches and tornado warnings had roughly doubled, resulting in a significant increase in the POD for tornado warnings to 0.35. The report card score also improved to a passing grade of 56.6/100. Further exploration of the results showed enhanced performance for tornadoes that occurred within Doppler radar range, when the parent thunderstorm involved supercell processes, and for tornadoes rated EF2 or higher. A number of recommendations are made aimed at further improvements to tornado alerting performance

    Impacts of cover crops and crop residues on phosphorus losses in cold climates: a review

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    Non-Peer ReviewedThe use of plants in riparian buffers or cover crops is widely proposed as a strategy to mitigate sediment and nutrient losses from land to water. In cold climates, concerns may arise with regard to potentially elevated phosphorus (P) losses associated with freeze-thaw of plant materials. Here, we review the impacts of cover crops and crop residues on P loss in cold climates, and explore linkages between water extractable P in the plant materials and P loss in surface runoff and subsurface drainage from cropped soils. Water extractable P in plants is greatly affected by crop species and hardiness, as well as freezing regimes including both freezing temperature and the number of freeze-thaw cycles. Although controls on water extractable P in plant tissues and residues are relatively well understood, impacts on P runoff and leaching are inconsistent across studies due to the influences of soil, climate, and management factors. This review sheds light on improving winter crop cover management to minimize P losses from land to water in cold climates and points to future research needs. Specifically, more research is needed to understand interactions between soil, plant, hydrology, and management in influencing P loss, and to improve the assessment of crop contributions to P loss in field settings of cold climates. Further, the trade-offs between the concern over P and the control of sediment loss and nitrogen leaching should be acknowledged, as should the uncertainties of freezing and crop adaptability under future climate regimes

    Arrival time and magnitude of airborne fission products from the Fukushima, Japan, reactor incident as measured in Seattle, WA, USA

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    We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17-18 March 2011, we registered the first arrival of the airborne fission products 131-I, 132-I, 132-Te, 134-Cs, and 137-Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. We measured the evolution of the activities over a period of 23 days at the end of which the activities had mostly fallen below our detection limit. The highest detected activity amounted to 4.4 +/- 1.3 mBq/m^3 of 131-I on 19-20 March.Comment: 7 pages, 5 figures, published in Journal of Environmental Radioactivit

    Ferromagnetic resonance study of sputtered Co|Ni multilayers

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    We report on room temperature ferromagnetic resonance (FMR) studies of [tt Co2t|2t Ni]×\timesN sputtered films, where 0.1t0.60.1 \leq t \leq 0.6 nm. Two series of films were investigated: films with same number of Co|Ni bilayer repeats (N=12), and samples in which the overall magnetic layer thickness is kept constant at 3.6 nm (N=1.2/tt). The FMR measurements were conducted with a high frequency broadband coplanar waveguide up to 50 GHz using a flip-chip method. The resonance field and the full width at half maximum were measured as a function of frequency for the field in-plane and field normal to the plane, and as a function of angle to the plane for several frequencies. For both sets of films, we find evidence for the presence of first and second order anisotropy constants, K1K_1 and K2K_2. The anisotropy constants are strongly dependent on the thickness tt, and to a lesser extent on the total thickness of the magnetic multilayer. The Land\'e g-factor increases with decreasing tt and is practically independent of the multilayer thickness. The magnetic damping parameter α\alpha, estimated from the linear dependence of the linewidth, H\triangle H, on frequency, in the field in-plane geometry, increases with decreasing tt. This behaviour is attributed to an enhancement of spin-orbit interactions with tt decreasing and in thinner films, to a spin-pumping contribution to the damping.Comment: 18 pages, 13 figure

    Quantum phase transitions and thermodynamic properties in highly anisotropic magnets

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    The systems exhibiting quantum phase transitions (QPT) are investigated within the Ising model in the transverse field and Heisenberg model with easy-plane single-site anisotropy. Near QPT a correspondence between parameters of these models and of quantum phi^4 model is established. A scaling analysis is performed for the ground-state properties. The influence of the external longitudinal magnetic field on the ground-state properties is investigated, and the corresponding magnetic susceptibility is calculated. Finite-temperature properties are considered with the use of the scaling analysis for the effective classical model proposed by Sachdev. Analytical results for the ordering temperature and temperature dependences of the magnetization and energy gap are obtained in the case of a small ground-state moment. The forms of dependences of observable quantities on the bare splitting (or magnetic field) and renormalized splitting turn out to be different. A comparison with numerical calculations and experimental data on systems demonstrating magnetic and structural transitions (e.g., into singlet state) is performed.Comment: 46 pages, RevTeX, 6 figure

    Size Matters: Origin of Binomial Scaling in Nuclear Fragmentation Experiments

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    The relationship between measured transverse energy, total charge recovered in the detector, and size of the emitting system is investigated. Using only very simple assumptions, we are able to reproduce the observed binomial emission probabilities and their dependences on the transverse energy.Comment: 14 pages, including 4 figure

    Impact of CARDIOrespiratory FITness on Arrhythmia Recurrence in Obese Individuals With Atrial Fibrillation The CARDIO-FIT Study

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    AbstractBackgroundObesity begets atrial fibrillation (AF). Although cardiorespiratory fitness is protective against incident AF in obese individuals, its effect on AF recurrence or the benefit of cardiorespiratory fitness gain is unknown.ObjectivesThis study sought to evaluate the role of cardiorespiratory fitness and the incremental benefit of cardiorespiratory fitness improvement on rhythm control in obese individuals with AF.MethodsOf 1,415 consecutive patients with AF, 825 had a body mass index ≥27 kg/m2 and were offered risk factor management and participation in a tailored exercise program. After exclusions, 308 patients were included in the analysis. Patients underwent exercise stress testing to determine peak metabolic equivalents (METs). To determine a dose response, cardiorespiratory fitness was categorized as: low (<85%), adequate (86% to 100%), and high (>100%). Impact of cardiorespiratory fitness gain was ascertained by the objective gain in fitness at final follow-up (≥2 METs vs. <2 METs). AF rhythm control was determined using 7-day Holter monitoring and AF severity scale questionnaire.ResultsThere were no differences in baseline characteristics or follow-up duration between the groups defined by cardiorespiratory fitness. Arrhythmia-free survival with and without rhythm control strategies was greatest in patients with high cardiorespiratory fitness compared to adequate or low cardiorespiratory fitness (p < 0.001 for both). AF burden and symptom severity decreased significantly in the group with cardiorespiratory fitness gain ≥2 METs as compared to <2 METs group (p < 0.001 for all). Arrhythmia-free survival with and without rhythm control strategies was greatest in those with METs gain ≥2 compared to those with METs gain <2 in cardiorespiratory fitness (p < 0.001 for both).ConclusionsCardiorespiratory fitness predicts arrhythmia recurrence in obese individuals with symptomatic AF. Improvement in cardiorespiratory fitness augments the beneficial effects of weight loss. (Evaluating the Impact of a Weight Loss on the Burden of Atrial Fibrillation [AF] in Obese Patients; ACTRN12614001123639

    The Origins of Bagan: The archaeological landscape of Upper Burma to AD 1300.

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    The archaeological landscape of Upper Burma from the middle of the first millennium BC to the Bagan period in the 13th-14th century AD is a landscape of continuity. Finds of polished stone and bronze artifacts suggest the existence of early metal-using cultures in the Chindwin and Samon River Valleys, and along parts of the Ayeyarwady plain. Increasing technological and settlement complexity in the Samon Valley suggests that a distinctive culture whose agricultural and trade success can be read in the archaeological record of the Late Prehistoric period developed there. The appearance of the early urban "Pyu" system of walled central places during the early first millennium AD seems to have involved a spread of agricultural and management skills and population from the Samon. The leaders of the urban centres adopted Indic symbols and Sanskrit modes of kingship to enhance and extend their authority. The early urban system was subject over time to a range of stresses including siltation of water systems, external disruption and social changes as Buddhist notions of leadership eclipsed Brahmanical ones. The archaeological evidence indicates that a settlement was forming at Bagan during the last centuries of the first millennium AD. By the mid 11th century Bagan began to dominate Upper Burma, and the region began a transition from a system of largely autonomous city states to a centralised kingdom. Inscriptions of the 11th to 13th centuries indicate that as the Bagan Empire expanded it subsumed the agricultural lands that had been developed by the Pyu

    The product of a Petrine circle? A reassessment of the origin and character of 1 Peter

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    © 2002 SAGE PublicationsRecent studies of 1 Peter, especially by John Elliott, have sought to rescue the letter from its assimilation to the Pauline tradition and to establish the view, now widely held, that 1 Peter is the distinctive product of a Petrine circle. After examining the traditions in 1 Peter, both Pauline and non-Pauline, and the names in the letter (Silvanus, Mark and Peter), this essay argues that there is no substantial evidence, either inside or outside the letter, to support the view of 1 Peter as originating from a specifically Petrine group. It is much more plausibly seen as reflecting the consolidation of early Christian traditions in Roman Christianity. Despite the scholarly majority currently in its favour, the view of 1 Peter as the distinctive product of a Petrine tradition from a Petrine circle should therefore be rejected

    Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector

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    The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that customized Broad Energy Germanium (BEGe) detectors produced by Canberra have several desirable features for a neutrinoless double-beta decay experiment, including low electronic noise, excellent pulse shape analysis capabilities, and simple fabrication. We have deployed a customized BEGe, the MAJORANA Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and shield at the Kimballton Underground Research Facility in Virginia. This paper will focus on the detector characteristics and measurements that can be performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure
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