485 research outputs found

    Cosmic ray short burst observed with the Global Muon Detector Network (GMDN) on June 22, 2015

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    We analyze the short cosmic ray intensity increase ("cosmic ray burst": CRB) on June 22, 2015 utilizing a global network of muon detectors and derive the global anisotropy of cosmic ray intensity and the density (i.e. the omnidirectional intensity) with 10-minute time resolution. We find that the CRB was caused by a local density maximum and an enhanced anisotropy of cosmic rays both of which appeared in association with Earth's crossing of the heliospheric current sheet (HCS). This enhanced anisotropy was normal to the HCS and consistent with a diamagnetic drift arising from the spatial gradient of cosmic ray density, which indicates that cosmic rays were drifting along the HCS from the north of Earth. We also find a significant anisotropy along the HCS, lasting a few hours after the HCS crossing, indicating that cosmic rays penetrated into the inner heliosphere along the HCS. Based on the latest geomagnetic field model, we quantitatively evaluate the reduction of the geomagnetic cut-off rigidity and the variation of the asymptotic viewing direction of cosmic rays due to a major geomagnetic storm which occurred during the CRB and conclude that the CRB is not caused by the geomagnetic storm, but by a rapid change in the cosmic ray anisotropy and density outside the magnetosphere.Comment: accepted for the publication in the Astrophysical Journa

    Gain Enhancement of a Dual-Band Planar Slot Dipole using AMC Plane for WBAN and WLAN Applications

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    A dual band slot dipole antenna made from textile is proposed for Wireless Body Area Network and Wireless Local Area Network applications. The proposed antenna is integrated with an artificial magnetic conductor plane to mitigate backward radiation and reduce Specific Absorption Rate when operated on body. The artificial magnetic conductor plane is formed using a 3 x 3 array of unit cells, each consisting of a square patch integrated with diamond-shaped slot. The proposed antenna (denoted as Antenna B) is compared against another similar antenna (Antenna A) in free space and on-body, in flat condition (on chest) and under two bending axes (x- and y-axes) on the upper arm. Results indicate that Antenna B provided wider upper bandwidth to 766 MHz (in flat condition) and up to 875 MHz when bent. Besides that, higher gain of up to 5 dB with improved front-to-back ratio are also observed

    linical challenges in Crohn s disease

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    Introduction: Crohn s disease is a chronic inflammatory disease from gastrointestinal tract. The increase in incidence and heterogeneity of this pathology, with different presentations and prognostics leads to a constant concern in developing and improving its classification and treatment. Objectives: To establish recommendations (based on level of evidence and recommendation grades) to 5 questions considered as the clinical challenges of the therapeutic approach in Crohn s disease. Methods: The methodology adopted by the working group DC2 (Desafios Clínicos na Doença de Crohn) was based on the selection of 5 questions, by voting, and establishing recommendations to each question proposed to each subgroup. Discussion and approval of reflexions and final recommendations was carried out in a consensus meeting. Conclusion: It has been possible to base conclusions about the questions under study on evidence, being recommended: 1) having Crohn s disease under 40 years old, structuring phenotype disease and anal disease are predictive factors of bad prognostic; 2) it is possible to consider suspension of biologics in patients with endoscopic remission and normal biomarkers; 3) patients with biochemical markers of disease activity (CRP and calprotectina) have more probability of relapse; 4) in failure of biologics it is essential to assure that treatment with the first drug was optimized: with infliximab it s demonstrated that either reduction of the administration range or increasing the dose allows to recover the response in the majority of patients; as for adalimumab, patients should change from bimonthly to weekly administrations; 5) in case of Crohn s disease with intestinal surgery, use of therapeutic to reduce postoperative recurrence is indicated, particularly immunosupressors and biologics

    Sizing a conventional diesel oxidation catalyst to be used for RCCI combustion under real driving conditions

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    [EN] Reactivity controlled compression ignition (RCCI) combustion has demonstrated to be able to avoid the NOx-soot trade-off appearing during conventional diesel combustion (CDC), with similar or better thermal efficiency than CDC under a wide variety of engine platforms. However, a major challenge of this concept comes from the high hydrocarbon (HC) and carbon monoxide (CO) emission levels, which are orders of magnitude greater than CDC, and similar to those of port fuel injected (PFI) gasoline engines. The high HC and CO emissions levels combined with the low exhaust temperatures during RCCI operation could present a challenge for the current exhaust aftertreatment technologies. The objective of this work is to evaluate the potential of a conventional diesel oxidation catalyst (DOC) for light-duty diesel engines when operating under dual-fuel RCCI diesel-gasoline combustion and to define its necessary size to accomplish with the current emissions standards. For this purpose, a 1-D model has been developed and calibrated through gas emissions measurements upstream and downstream the DOC under different engine steady-state conditions. After that, the DOC response in transient conditions has been evaluated by means of vehicle systems simulations under different driving cycles representative of the homologation procedures currently in force around the world. The results show that the HC and CO levels at the DOC outlet are unacceptable considering the different emissions regulations. By this reason, a dedicated study to define the DOC size needed to accomplish the different emissions standards is carried out. The results suggest that, the DOC volume needed to fulfill the type approval regulation limits ranges from four to six times the original volume.The authors gratefully acknowledge General Motors Global Research & Development for providing the engine used in this investigation. The authors also acknowledge FEDER and Spanish Ministerio de Economia y Competitividad for partially supporting this research through TRANCO project (TRA2017-87694-R).García Martínez, A.; Piqueras, P.; Monsalve-Serrano, J.; Lago-Sari, R. (2018). Sizing a conventional diesel oxidation catalyst to be used for RCCI combustion under real driving conditions. Applied Thermal Engineering. 140:62-72. https://doi.org/10.1016/j.applthermaleng.2018.05.043S627214

    AVERAGE SPATIAL DISTRIBUTION OF COSMIC RAYS BEHIND THE INTERPLANETARY SHOCK-GLOBAL MUON DETECTOR NETWORK OBSERVATIONS

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    We analyze the galactic cosmic ray (GCR) density and its spatial gradient in Forbush Decreases (FDs) observed with the Global Muon Detector Network (GMDN) and neutron monitors (NMs). By superposing the GCR density and density gradient observed in FDs following 45 interplanetary shocks (IP-shocks), each associated with an identified eruption on the Sun, we infer the average spatial distribution of GCRs behind IP-shocks. We find two distinct modulations of GCR density in FDs, one in the magnetic sheath and the other in the coronal mass ejection (CME) behind the sheath. The density modulation in the sheath is dominant in the western flank of the shock, while the modulation in the CME ejecta stands out in the eastern flank. This east-west asymmetry is more prominent in GMDN data responding to similar to 60 GV GCRs than in NM data responding to similar to 10 GV GCRs, because of the softer rigidity spectrum of the modulation in the CME ejecta than in the sheath. The geocentric solar ecliptic-y component of the density gradient, G(y), shows a negative (positive) enhancement in FDs caused by the eastern (western) eruptions, while G(z) shows a negative (positive) enhancement in FDs caused by the northern (southern) eruptions. This implies that the GCR density minimum is located behind the central flank of IP-shocks and propagating radially outward from the location of the solar eruption. We also confirmed that the average Gz changes its sign above and below the heliospheric current sheet, in accord with the prediction of the drift model for the large-scale GCR transport in the heliosphere.ArticleASTROPHYSICAL JOURNAL. 825(2):100 (2016)journal articl

    Network 'small-world-ness': a quantitative method for determining canonical network equivalence

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    Background: Many technological, biological, social, and information networks fall into the broad class of 'small-world' networks: they have tightly interconnected clusters of nodes, and a shortest mean path length that is similar to a matched random graph (same number of nodes and edges). This semi-quantitative definition leads to a categorical distinction ('small/not-small') rather than a quantitative, continuous grading of networks, and can lead to uncertainty about a network's small-world status. Moreover, systems described by small-world networks are often studied using an equivalent canonical network model-the Watts-Strogatz (WS) model. However, the process of establishing an equivalent WS model is imprecise and there is a pressing need to discover ways in which this equivalence may be quantified. Methodology/Principal Findings: We defined a precise measure of 'small-world-ness' S based on the trade off between high local clustering and short path length. A network is now deemed a 'small-world' if S. 1-an assertion which may be tested statistically. We then examined the behavior of S on a large data-set of real-world systems. We found that all these systems were linked by a linear relationship between their S values and the network size n. Moreover, we show a method for assigning a unique Watts-Strogatz (WS) model to any real-world network, and show analytically that the WS models associated with our sample of networks also show linearity between S and n. Linearity between S and n is not, however, inevitable, and neither is S maximal for an arbitrary network of given size. Linearity may, however, be explained by a common limiting growth process. Conclusions/Significance: We have shown how the notion of a small-world network may be quantified. Several key properties of the metric are described and the use of WS canonical models is placed on a more secure footing
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