Many patients with chronic obstructive lung disease show increased airways responsiveness to histamine. We investigated the hypothesis that increased airways responsiveness predicts the development ...and remission of chronic respiratory symptoms.
We used data from 24-year follow-up (1965–90) of 2684 participants in a cohort study in Vlagtwedde and Vlaardingen, Netherlands. Increased airways responsiveness was defined as a PC
10 value (concentration of histamine for which challenge led to a 10% fall in forced expiratory volume in 1 s) of less than 8 mg/mL. Information on respiratory symptoms was collected by means of a standard questionnaire every 3 years. Logistic regression was used to control for age, area of residence, cigarette smoking status, and sex.
Participants with increased airways responsiveness (1281 observations) were more likely than those without increased airways responsiveness (5801 observations) to develop the following symptoms during any 3-year follow-up interval: chronic cough (odds ratio 1·9 95% CI 1·2–2·9), chronic phlegm (2·0 1·3–3·0), dyspnoea (2·3 1·5–3·5), asthmatic attacks (3·7 2·2–6·1), and persistent wheeze (2·7 1·7–4·4). The estimate of the odds ratio for the development of any of the six symptoms was 1·7 (1·2–2·3). Participants with increased airways responsiveness were less likely than those without this characteristic to show remission of these respiratory symptoms. The estimate of the odds ratio for the remission of any of the six symptoms was 0·42 (0·28–0·61).
These prospective analyses show that increased airways responsiveness is positively associated with the development of chronic respiratory symptoms and negatively associated with the remission of these symptoms in adults.
Theory and simulations suggest that magnetic fields from radio jets and lobes powered by their central super massive black holes can be an important source of magnetic fields in the galaxy clusters. ...This is Paper II in a series of studies where we present self-consistent high-resolution adaptive mesh refinement cosmological magnetohydrodynamic simulations that simultaneously follow the formation of a galaxy cluster and evolution of magnetic fields ejected by an active galactic nucleus. We studied 12 different galaxy clusters with virial masses ranging from 1 X 1014 to 2 X 1015 M . In this work, we examine the effects of the mass and merger history on the final magnetic properties. We find that the evolution of magnetic fields is qualitatively similar to those of previous studies. In most clusters, the injected magnetic fields can be transported throughout the cluster and be further amplified by the intracluster medium (ICM) turbulence during the cluster formation process with hierarchical mergers, while the amplification history and the magnetic field distribution depend on the cluster formation and magnetism history. This can be very different for different clusters. The total magnetic energies in these clusters are between 4 X 1057 and 1061 erg, which is mainly decided by the cluster mass, scaling approximately with the square of the total mass. Dynamically older relaxed clusters usually have more magnetic fields in their ICM. The dynamically very young clusters may be magnetized weakly since there is not enough time for magnetic fields to be amplified.
This article presents results of a wide-band measurement campaign conducted at 38 GHz. The objective of the research was to determine multipath and time varying channel behavior of short-hop ...millimeter-wave point-to-multipoint radio links during various weather events. 73963 power delay profiles (PDPs) were captured on three links, each comparable to proposed local multipoint distribution systems (LMDS) in a campus environment. Multipath was observed in unobstructed LOS links during rain but not during clear weather. Short-term variation of the received signal over 1-2 min observation periods is described by a Rician distribution with a K factor which varies as a function of rain rate. Measured rain attenuation exceeds Crane's (1996) model predictions by several decibels. A novel prediction technique is presented that applies canonical antenna patterns and site specific information to estimate worst case multipath channel characteristics including relative power, time of arrival (TOA), and angle of arrival (AOA) of each multipath component. New metrics, the excess delay zone and relative power zone, are defined and contour plots are developed to determine potential reflectors from an area site map. These results and models provide useful guidelines for the design of millimeter-wave wireless communication systems.
Ziele:
Ziel dieser Studie war es zu zeigen ob die nichtinvasive MRT der Carotiden in der Lage ist i.) die Zusammensetzung arteriosklerotischer Plaques korrekt wiederzugeben und ii.) ...arteriosklerotische Plaquekomponenten zu quantifizieren.
Methode:
40 Patienten wurden vor einer geplanten Carotis-Endarteriektomie mit einem 1.5 Tesla MR-Tomographen untersucht. Es wurde ein standardisiertes Protokoll mit fettunterdrückten T1-, PD- und T2-gewichteten Fastspinechosequenzen sowie 3D time-of-flight (3D-TOF) verwendet. MRT-Bilder wurden mit der Histopathologie anhand von der Form des Gefäßlumens und der Form der Gefäßwand korreliert. Folgende Plaquekomponenten wurden identifiziert und quantifiziert: Lipid/Necrotic Core (L/NC), Verkalkungen (Ca), extrazelluläre Matrix (EZM) und Hemorrhage. Sensitivität (S), Spezifität (SP) und Cohen“s kappa (κ) wurde für alle Plaquekomponenten >2mm2 berechnet. Der Pearson Korrelations-Koeffizient wurde verwendet um die gemessenen Flächen (MRT versus Histopathologie) zu vergleichen.
Ergebnis:
MRT war in der Lage die Plaquekomponenten mit guter Sensitivität und Spezifität zu identifizieren: L/NC (S=95%,SP=76%,κ=0.73), Ca(S=84%,SP=91%,κ=0.75), Hemorrhage(S=87%,SP=84%,k=0.71) und EZM(S=79%,SP=77%,κ=0.53). MRT-Flächenmessungen zeigten eine gute Korrelation zur Histopathologie für die minimale Gefäßlumenfläche(r=0.75,p<.001), maximale Gefäßwandfläche(r=0.7,p<.001), maximale L/NC-Fläche(r=0.69, p<.001), maximale Ca-Fläche(r=0.86,p<.001), maximale Hemorrhage-Fläche(r=0.66,p<.001) und eine schwache Korrelation für die maximale EZM-Fläche(r=0.4,p=.02).
Schlussfolgerung:
Die nichtinvasive MRT ist in der Lage verschiedene Komponenten arteriosklerotischer Plaques in der Arteria Carotis zu identifizieren und zu quantifizieren. Diese Methode kann dazu benutzt werden den Verlauf arteriosklerotischer Gefäßwandveränderungen zu untersuchen und kann dazu beitragen, vulnerable Plaques frühzeitig zu erkennen und zu behandeln.
Korrespondierender Autor:
Saam TS
University of Washington, Radiologie, 535 13th Ave E #601, 98102, Seattle, USA
E-Mail:
tsaam@gmx.net
Silicene has been predicted to be an extraordinary anode material for lithium-ion batteries with a large capacity and low lithium migration energy barriers, but the free-standing form of silicene is ...unstable, virtually requiring a substrate support. In this work, we propose to use graphene as a substrate and a protective layer of silicene, forming a van der Waals heterostructure of silicene and graphene (Si/G) to serve as a prospective anode material for lithium/sodium-ion batteries. Ab initio calculations show that the Si/G heterostructure not only preserves the silicene's large lithium/sodium capacity (487 mA h g-1) and low lithium/sodium migration energy barriers (<0.4 eV for lithium and <0.3 eV for sodium), but also provides much larger lithium/sodium binding energies via a synergistic effect, which can effectively inhibit the formation of dendrites. Density of states results show that the Si/G heterostructure is metallic before and after lithium/sodium intercalation, ensuring a good electronic conductivity. In addition, the mechanical stiffness of the Si/G heterostructure is found to be larger than that of pristine silicene or graphene, which helps preserve the structural integrity and enhance the cycle performance.
In this work, the mechanism of the ethanol oxidation reaction (EOR) on a palladium electrode was studied using the cyclic voltammetry method. The dissociative adsorption of ethanol was found to ...proceed rather quickly and the rate-determining step was the removal of the adsorbed ethoxi by the adsorbed hydroxyl on the Pd electrode. The Tafel slope was found to be 130
mV
dec
−1 at lower potentials, which suggests that the adsorption of OH
− ions follows the Temkin-type isotherm on the Pd electrode. In comparison, the Tafel slope increased gradually to 250
mV
dec
−1 at higher potentials. The change in the Tafel slope indicated that, at higher potentials, the kinetics is not only affected by the adsorption of the OH
− ions, but also by the formation of the inactive oxide layer on the Pd electrode.
Carbon-supported PdNi catalysts for the ethanol oxidation reaction in alkaline direct ethanol fuel cells are successfully synthesized by the simultaneous reduction method using NaBH
4 as reductant. ...X-ray diffraction characterization confirms the formation of the face-centered cubic crystalline Pd and Ni(OH)
2 on the carbon powder for the PdNi/C catalysts. Transmission electron microscopy images show that the metal particles are well-dispersed on the carbon powder, while energy-dispersive X-ray spectrometer results indicate the uniform distribution of Ni around Pd. X-ray photoelectron spectroscopy analyses reveal the chemical states of Ni, including metallic Ni, NiO, Ni(OH)
2 and NiOOH. Cyclic voltammetry and chronopotentiometry tests demonstrate that the Pd
2Ni
3/C catalyst exhibits higher activity and stability for the ethanol oxidation reaction in an alkaline medium than does the Pd/C catalyst. Fuel cell performance tests show that the application of Pd
2Ni
3/C as the anode catalyst of an alkaline direct ethanol fuel cell with an anion-exchange membrane can yield a maximum power density of 90
mW
cm
−2 at 60
°C.
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