1,877 research outputs found

    Commonality in the LME aluminium and copper volatility processes through a Figarch lens

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    We consider dynamic representation of spot and three month aluminium and copper volatilities. These are the two most important metals traded in the London Metal Exchange (LME). They share common business cycle factors and are traded under identical contract specifications. We apply the bivariate FIGARCH model which allows parsimonious representation of long memory volatility processes. Our results show that spot and three month aluminium and copper volatilities follow long memory processes, that they exhibit a common degree of fractional integration and that the processes are symmetric. However, there is no evidence that the processes are fractionally cointegrated. This high degree of commonality may result from the common LME trading process

    Price Variability and Marketing Method in the Non-Ferrous Metals Industry

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    We examine the impact of the pricing regime on price variability with reference to the non-ferrous metals industry. Theoretical arguments are ambiguous, but in any case suggests that the extent of monopoly power is more important than the pricing regime as determinant of variability. Slade (1991) argued that metals price volatility increased in the nineteen eighties relative to the seventies, and that this was associated with a move from administered producer pricing to exchange pricing. This claims are only partially supported. Extension of Slade's sample to the present indicates that any early differences between the variability of producer and exchange prices have now vanished.Metals, Futures trading, Exchange pricing, Producer pricing, Price volatility

    Commonality in the LME aluminium and copper volatility processes through a Figarch lens

    Get PDF
    We consider dynamic representation of spot and three month aluminium and copper volatilities. These are the two most important metals traded in the London Metal Exchange (LME). They share common business cycle factors and are traded under identical contract specifications. We apply the bivariate FIGARCH model which allows parsimonious representation of long memory volatility processes. Our results show that spot and three month aluminium and copper volatilities follow long memory processes, that they exhibit a common degree of fractional integration and that the processes are symmetric. However, there is no evidence that the processes are fractionally cointegrated. This high degree of commonality may result from the common LME trading process.

    Copper Price Discovery on Comex, the LME and the SHFE, 2001-2013

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    Over the past two decades, China has come to dominate international commerce in copper. The importance of the Shanghai Futures Exchange(SHFE) has increased in response to this development. We look at the distribution of price discovery between the SHFE and the two historically important copper futures exchanges, Comex and the LME. The resultsindicate that it is Comex, followed by the SHFE, not the LME which plays the most important role in copper price discovery. We also highlighta number of problems associated with both the calculation and interpretation of the standard IS and PT price discovery measures when used to look at overlapping price change on non-synchronous markets.The results offer a clearer interpretation in terms of trading slots (European, North American and Asian trading days) than in terms of exchanges

    Wegener Granulomatosis Revealed by Pleural Effusion

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    Pulmonary signs are common in Wegener's granulomatosis (WG). However, an initial presentation including pleural effusion has not been described. We describe a case of WG in which pleural effusion was the first clinical manifestation. A 45-year-old man with dorsal pain presented with pleural thickening and effusion, and a visible nodule on a thoracic scan. A dense chronic inflammatory infiltrate was obtained by pleural biopsy and an open lung biopsy revealed necrotizing granulomatous vasculitis. Serologies were positive for antineutrophil cytoplasmic antibodies and antiproteinase 3 antibodies. A diagnosis of WG was conducted and the patient was started on cyclophosphamide and methylprednisolone as an initial treatment, with a favorable evolution. Although pleural effusion is rarely described in WG, this pathology must be considered in the presence of this clinical manifestation

    Similar self-organizing scale-invariant properties characterize early cancer invasion and long range species spread

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    Occupancy of new habitats through dispersion is a central process in nature. In particular, long range dispersal is involved in the spread of species and epidemics, although it has not been previously related with cancer invasion, a process that involves spread to new tissues. We show that the early spread of cancer cells is similar to the species individuals spread and that both processes are represented by a common spatio-temporal signature, characterized by a particular fractal geometry of the boundaries of patches generated, and a power law-scaled, disrupted patch size distribution. We show that both properties are a direct result of long-distance dispersal, and that they reflect homologous ecological processes of population self-organization. Our results are significant for processes involving long-range dispersal like biological invasions, epidemics and cancer metastasis.Comment: 21 pages, 2 figure

    Double reading of outsourced CT/MR radiology reports

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    OBJECTIVES: Our objective was to determine disagreement rates in radiological reports provided by using a double-reading protocol in a national teleradiology company. METHODS: From January 2015 to July 2016, 134169 radiological exams from 36 French centers, benefited outsourced interpretations by certified radiologists, in both regular and after-hours activities. Of these, 2040 CT and MR-scans (1.5%) were subjected to a second opinion by other radiologists in the field of their anatomical specialty (cerebral, thoracic, abdominal-pelvic, and osteoarticular). A five-point agreement scale graded from 0 to 4 was assigned for each exam. Disagreements were considered as minor if no clinical consequence for patient (scores 1 and 2) and major if potential clinical consequence (score 3 and 4). Independent radiologists performed a retrospective analysis and a stratified statistical analysis. RESULTS: Double reading was performed on CT-scans (n = 934/2040, 45.8%) and MR-scans (n = 1106/2040, 54.2%) performed in regular (80.1%) and after-hours activities (19.9%). Disagreement scores occurred in 437 exams (21.4%), including major disagreements in 59 (2.9%). Among these, 48/754 were assigned by the thoracic second reader (6.4%), 6/70 by the abdominal-pelvic second reader (8.6%), 3/901 by the osteoarticular second reader (0.3%), and 2/315 by the cerebral second reader (0.6%), with statistical significant difference. No additional disagreement rate was observed in regular and after-hours activities (P = 0.63). CONCLUSIONS: Double-reading of outsourced CT and MRI interpretations yielded 21.4% disagreement rate, with potential clinical consequence for patient in 2,9% of the cases. These results are in accordance with those previously reported and suggests that quality assurance of outsourced interpretations is needed

    Nasal High Flow at 25 L/min or Expiratory Resistive Load Do Not Improve Regional Lung Function in Patients With COPD: A Functional CT Imaging Study

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    BackgroundNasal high flow (NHF) is a non-invasive breathing therapy that is based on the delivery via a large-caliber nasal cannula of heated and humidified air at flow rates that exceed peak inspiratory flow. It is thought that positive airway pressure generated by NHF can help reduce gas trapping and improve regional lung ventilation. There are no data to confirm this hypothesis at flow rates applicable in stable chronic obstructive pulmonary disease (COPD) patients.MethodsIn this study, we used non-rigid registration of computed tomography (CT) images acquired at maximal expiration and inspiration to compute regional lung attenuation changes (ΔHU), and lung displacement (LD), indices of regional lung ventilation. Parametric response maps (Galban et al., 2012) were also computed in each experimental condition. Eight COPD patients were assessed at baseline (BL) and after 5 min of NHF and expiratory resistive loading (ERL).ResultsΔHU was: BL (median, IQR): 85 (67.2, 102.8); NHF: 90.7 (57.4, 97.6); ERL: 74.6 (46.4, 89.6) HU (p = 0.531); and LD: 27.8 (22.3, 39.3); 17.6 (15.4, 27.9); and 20.4 (16.6, 23.6) mm (p = 0.120) in the 3 conditions, respectively. No significant difference in trapping was observed. Respiratory rate significantly decreased with both treatments [BL: 17.3 (16.4, 18.9); NHF: 13.7; ERL: 11.4 (9.6, 13.2) bpm; and p < 0.001].ConclusionNeither NHF at 25 L/min nor ERL significantly improved the regional lung ventilation of stable COPD patients with gas trapping, based on functional lung CT imaging. Further study including more subjects is needed to assess the potential effect of NHF on regional lung function at higher flow rates.Clinical Trial Registrationwww.clinicaltrials.gov/under, identifier NCT03821311

    The Paleo-Indian Entry into South America According to Mitogenomes

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    Recent and compelling archaeological evidence attests to human presence 14.5 ka at multiple sites in South America and a very early exploitation of extreme high-altitude Andean environments. Considering that, according to genetic evidence, human entry into North America from Beringia most likely occurred 16 ka, these archeological findings would imply an extremely rapid spread along the double continent. To shed light on this issue from a genetic perspective, we first completely sequenced 217 novel modern mitogenomes of Native American ancestry from the northwestern area of South America (Ecuador and Peru); we then evaluated them phylogenetically together with other available mitogenomes (430 samples, both modern and ancient) from the same geographic area and, finally, with all closely related mitogenomes from the entire double continent. We detected a large number (NΠ48) of novel subhaplogroups, often branching into further subclades, belonging to two classes: those that arose in South America early after its peopling and those that instead originated in North or Central America and reached South America with the first settlers. Coalescence age estimates for these subhaplogroups provide time boundaries indicating that early Paleo-Indians probably moved from North America to the area corresponding to modern Ecuador and Peru over the short time frame of 1.5 ka comprised between 16.0 and 14.6 ka
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