119 research outputs found

    Tests of sunspot number sequences: 1. Using ionosonde data

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    More than 70 years ago it was recognised that ionospheric F2-layer critical frequencies [foF2] had a strong relationship to sunspot number. Using historic datasets from the Slough and Washington ionosondes, we evaluate the best statistical fits of foF2 to sunspot numbers (at each Universal Time [UT] separately) in order to search for drifts and abrupt changes in the fit residuals over Solar Cycles 17-21. This test is carried out for the original composite of the Wolf/Zürich/International sunspot number [R], the new “backbone” group sunspot number [RBB] and the proposed “corrected sunspot number” [RC]. Polynomial fits are made both with and without allowance for the white-light facular area, which has been reported as being associated with cycle-to-cycle changes in the sunspot number - foF2 relationship. Over the interval studied here, R, RBB, and RC largely differ in their allowance for the “Waldmeier discontinuity” around 1945 (the correction factor for which for R, RBB and RC is, respectively, zero, effectively over 20 %, and explicitly 11.6 %). It is shown that for Solar Cycles 18-21, all three sunspot data sequences perform well, but that the fit residuals are lowest and most uniform for RBB. We here use foF2 for those UTs for which R, RBB, and RC all give correlations exceeding 0.99 for intervals both before and after the Waldmeier discontinuity. The error introduced by the Waldmeier discontinuity causes R to underestimate the fitted values based on the foF2 data for 1932-1945 but RBB overestimates them by almost the same factor, implying that the correction for the Waldmeier discontinuity inherent in RBB is too large by a factor of two. Fit residuals are smallest and most uniform for RC and the ionospheric data support the optimum discontinuity multiplicative correction factor derived from the independent Royal Greenwich Observatory (RGO) sunspot group data for the same interval

    Triage of patients with venous and lymphatic diseases during the COVID-19 pandemic – The Venous and Lymphatic Triage and Acuity Scale (VELTAS):: A consensus document of the International Union of Phlebology (UIP), Australasian College of Phlebology (ACP), American Vein and Lymphatic Society (AVLS), American Venous Forum (AVF), European College of Phlebology (ECoP), European Venous Forum (EVF), Interventional Radiology Society of Australasia (IRSA), Latin American Venous Forum, Pan-American Society of Phlebology and Lymphology and the Venous Association of India (VAI)

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    The coronavirus disease 2019 (COVID-19) global pandemic has resulted in diversion of healthcare resources to the management of patients infected with SARS-CoV-2 virus. Elective interventions and surgical procedures in most countries have been postponed and operating room resources have been diverted to manage the pandemic. The Venous and Lymphatic Triage and Acuity Scale was developed to provide an international standard to rationalise and harmonise the management of patients with venous and lymphatic disorders or vascular anomalies. Triage urgency was determined based on clinical assessment of urgency with which a patient would require medical treatment or surgical intervention. Clinical conditions were classified into six categories of: (1) venous thromboembolism (VTE), (2) chronic venous disease, (3) vascular anomalies, (4) venous trauma, (5) venous compression and (6) lymphatic disease. Triage urgency was categorised into four groups and individual conditions were allocated to each class of triage. These included (1) medical emergencies (requiring immediate attendance), example massive pulmonary embolism; (2) urgent (to be seen as soon as possible), example deep vein thrombosis; (3) semiurgent (to be attended to within 30-90 days), example highly symptomatic chronic venous disease, and (4) discretionary/nonurgent- (to be seen within 6-12 months), example chronic lymphoedema. Venous and Lymphatic Triage and Acuity Scale aims to standardise the triage of patients with venous and lymphatic disease or vascular anomalies by providing an international consensus-based classification of clinical categories and triage urgency. The scale may be used during pandemics such as the current COVID-19 crisis but may also be used as a general framework to classify urgency of the listed conditions

    IMG 305 - PEMBUNGKUSAN MAKANAN NOV.05.

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    We discuss the use of Agent-based Modelling for the development and testing of theories about emergent social phenomena in marketing and the social sciences in general. We address both theoretical aspects about the types of phenomena that are suitably addressed with this approach and practical guidelines to help plan and structure the development of a theory about the causes of such a phenomenon in conjunction with a matching ABM. We argue that research about complex social phenomena is still largely fundamental research and therefore an iterative and cyclical development process of both theory and model is to be expected. To better anticipate and manage this process, we provide theoretical and practical guidelines. These may help to identify and structure the domain of candidate explanations for a social phenomenon, and furthermore assist the process of model implementation and subsequent development. The main goal of this paper was to make research on complex social systems more accessible and help anticipate and structure the research process

    Hydrothermal system in Southern Grass Valley, Pershing County, Nevada

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    Southern Grass Valley is a fairly typical extensional basin in the Basin and Range province. Leach Hot Springs, in the southern part of the valley, represents the discharge end of an active hydrothermal flow system with an estimated deep aquifer temperature of 163 to 176/sup 0/C. Results of geologic, hydrologic, geophysical and geochemical investigations are discussed in an attempt to construct an internally consistent model of the system

    Wide-ranging timescales of subsurface phosphorus transport from field to stream in a tile drained landscape

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    In agricultural areas with poorly drained soils, subsurface tile drains are commonly installed to improve drainage but also serve as conduits that deliver excess nutrients to adjacent streams. Our goal was to understand the transport of phosphorus (P) along these flow paths by applying a novel mixture of tracers (including 866 g of conservative chloride (Cl), 3.4 g of potassium phosphate, and approximately 3.6 × 1011 fluorescent micrometer-sized particles, or 49.5 g) to a farm field and sampling their breakthrough curves at the outlet to a stream, approximately 30 m away. Simultaneously, we performed a 26-h time-lapse electrical resistivity tomography (ERT) survey to monitor the saline tracer migration in three dimensions every 0.5 to 1 h. The initial pulse of tracers had a mean arrival time of 21 min and transported 262 g of added Cl (28 %), 0.65 g of dissolved P (17 %), and 1.4 × 1010 particles (4 %) to the tile drain outlet. A stochastic mobile-immobile model fit the anomalous (non-Fickian) solute breakthrough curves, where the mobile zone represents the macropore and tile drain network, and the immobile zone represents the soil matrix. Residence times in the immobile zone exhibited a heavy (power-law) tail. ERT images confirmed the retention of tracer mixture in soils after concentrations were no longer measurable at the tile drain outlet. Core samples suggest that 96 % of particles and 21 % of dissolved P were retained within 10.5 cm of the application location. Solutes and particles were remobilized over longer timescales during three successive storms. Exported masses of Cl and dissolved P at the tile drain outlet ranged from 1,490–12,300 g and 25.7–65.2 g, respectively, indicating flushing of older Cl and P stored in soils before the tracer experiment. Less than 0.01 % of the added fluorescent particles were flushed during these storm events. This study indicates the wide range of P travel times through the subsurface in tile drained landscapes and the need to incorporate non-Fickian transport behavior in models

    Toward standardization of cardiac troponin I measurements part II: assessing commutability of candidate reference materials and harmonization of cardiac troponin I assays

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    BACKGROUND: Cardiac tropoin I (cTnI) measurements show an approximately 20- to 40-fold difference between assays, and better standardization and harmonization are needed. Toward this goal, the AACC cTnI Standardization Committee collaborated with the National Institute of Standards and Technology (NIST) in an earlier study to select 2 candidate reference materials (cRMs). METHODS: Two troponin cRMs, a troponin C-troponin I-troponin T (CIT) complex from human heart tissue and a CIT complex from recombinant technology, were supplied to NIST for assessment of composition and purity, and cTnI value assignment. These cRMs and 6 cTnI-positive human serum pools were shipped to manufacturers of 15 cTnI assays. Commutability of the materials was examined by determining the numerical relationship for the cRM preparations between each manufacturer-specified field method and each of the other 14 field methods. These relationships were then compared with the corresponding numerical relationships for the human serum pools. Harmonization of methods was accomplished by determining regression parameters relative to the analytical system yielding values closest to the median for each serum pool. These regression parameters were used to recalculate pool values to harmonize the assays. Interassay CVs before and after harmonization were determined. RESULTS: Characterization of the CIT and CI cRMs showed that these materials were of specified composition. The proportion of cTnI methods that demonstrated commutability for the CIT cRM was 45%; for the CI cRM, 39% of methods demonstrated commutability. Interassay cTnI variability for the field methods ranged from 82% to 97%, median 88%. After harmonization, variability of the serum pools for the cTnI methods was decreased to between 9.0% and 23%, median 15.5%. CONCLUSIONS: The proportion of methods demonstrating commutability was too low for use as a common calibrator for the cTnI field methods. However a simple strategy using serum pools can improve harmonization of field cTnI methods by more than 5-fold. The CIT cRM was selected by the AACC cTnI standardization committee, and a new lot has been classified as the cTnI certified reference material Standard Reference Material 2921 by NIST
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