Transient magnetotransport through a quantum wire

We consider an ideal parabolic quantum wire in a perpendicular magnetic field. A simple Gaussian shaped scattering potential well or hill is flashed softly on and off with its maximum at $t=0$, mimicking a temporary broadening or narrowing of the wire. By an extension of the Lippmann-Schwinger formalism to time-dependent scattering potentials we investigate the effects on the continuous current that is driven through the quantum wire with a vanishingly small forward bias. The Lippmann-Schwinger approach to the scattering process enables us to investigate the interplay between geometrical effects and effects caused by the magnetic field.Comment: RevTeX (pdf-LaTeX), 11 pages with 15 included jpg figure

Time-dependent magnetotransport of a wave packet in a quantum wire with embedded quantum dots

We consider wave packet propagation in a quantum wire with either an embedded antidot or an embedded parallel double open quantum dot under the influence of a uniform magnetic field. The magnetoconductance and the time evolution of an electron wave packet are calculated based on the Lippmann-Schwinger formalism. This approach allows us to look at arbitrary embedded potential profiles and illustrate the results by performing computational simulations for the conductance and the time evolution of the electron wave packet through the quantum wire. In the double-dot system we observe a long-lived resonance state that enhances the spatial spreading of the wave packet, and quantum skipping-like trajectories are induced when the envelop function of the wave packet covers several subbands in appropriate magnetic fields.Comment: RevTeX, 9 pages with 8 included postscript figure

Ambient nitrogen dioxide is associated with emergency hospital visits for atrial fibrillation: a population-based case-crossover study in Reykjavik, Iceland.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadBackground: In Iceland air quality is generally good; however, previous studies indicate that there is an association between air pollution in Reykjavik and adverse health effects as measured by dispensing of medications, mortality, and increase in health care utilisation. The aim was to study the association between traffic-related ambient air pollution in the Reykjavik capital area and emergency hospital visits for heart diseases and particularly atrial fibrillation and flutter (AF). Methods: A multivariate time-stratified case-crossover design was used to study the association. Cases were those patients aged 18 years or older living in the Reykjavik capital area during the study period, 2006-2017, who made emergency visits to Landspitali University Hospital for heart diseases. In this population-based study, the primary discharge diagnoses were registered according to International Classification of Diseases, 10th edition (ICD-10). The pollutants studied were NO2, PM10, PM2.5, and SO2, with adjustment for H2S, temperature, and relative humidity. The 24-h mean of pollutants was used with lag 0 to lag 4. Results: During the study period 9536 cases of AF were identified. The 24-h mean NO2 was 20.7 μg/m3. Each 10 μg/m3 increase in NO2 was associated with increased risk of heart diseases (ICD-10: I20-I25, I44-I50), odds ratio (OR) 1.023 (95% CI 1.012-1.034) at lag 0. Each 10 μg/m3 increase in NO2 was associated with an increased risk of AF (ICD-10: I48) on the same day, OR 1.030 (95% CI: 1.011-1.049). Females were at higher risk for AF, OR 1.051 (95% CI 1.019-1.083) at lag 0, and OR 1.050 (95% CI 1.019-1.083) at lag 1. Females aged younger than 71 years had even higher risk for AF, OR 1.077 (95% CI: 1.025-1.131) at lag 0. Significant associations were found for other pollutants and emergency hospital visits, but they were weaker and did not show a discernable pattern. Conclusions: Short-term increase in NO2 concentrations was associated with heart diseases, more precisely with AF. The associations were stronger among females, and among females at younger age. This is the first study in Iceland that finds an association between air pollution and cardiac arrhythmias, so the results should be interpreted with caution. Keywords: Atrial fibrillation; Cardiac arrhythmia; Case-crossover; Hospital registry; Ischemic heart diseases; Nitrogen dioxide; Population-based

Ambient air pollution and emergency department visits and hospitalisation for cardiac arrest : a population-based case-crossover study in Reykjavik, Iceland

Publisher Copyright: © Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Publisher Copyright: © 2023 Authors. All rights reserved.OBJECTIVES: To assess the association between traffic-related ambient air pollution and emergency hospital visits for cardiac arrest. DESIGN: Case-crossover design was used with a lag time to 4 days. SETTING: The Reykjavik capital area and the study population was the inhabitants 18 years and older identified by encrypted personal identification numbers and zip codes. PARTICIPANTS AND EXPOSURE: Cases were those with emergency visits to Landspitali University Hospital during the period 2006-2017 and who were given the primary discharge diagnosis of cardiac arrest according to the International Classification of Diseases 10th edition (ICD-10) code I46. The pollutants were nitrogen dioxide (NO2), particulate matter with aerodynamic diameter less than 10 µm (PM10), particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5) and sulfur dioxide (SO2) with adjustment for hydrogen sulfide (H2S), temperature and relative humidity. MAIN OUTCOME MEASURE: OR and 95% CIs per 10 µg/m3 increase in concentration of pollutants. RESULTS: The 24-hour mean NO2 was 20.7 µg/m3, mean PM10 was 20.5 µg/m3, mean PM2.5 was 12.5 µg/m3 and mean SO2 was 2.5 µg/m3. PM10 level was positively associated with the number of emergency hospital visits (n=453) for cardiac arrest. Each 10 µg/m3 increase in PM10 was associated with increased risk of cardiac arrest (ICD-10: I46), OR 1.096 (95% CI 1.033 to 1.162) on lag 2, OR 1.118 (95% CI 1.031 to 1.212) on lag 0-2, OR 1.150 (95% CI 1.050 to 1.261) on lag 0-3 and OR 1.168 (95% CI 1.054 to 1.295) on lag 0-4. Significant associations were shown between exposure to PM10 on lag 2 and lag 0-2 and increased risk of cardiac arrest in the age, gender and season strata. CONCLUSIONS: A new endpoint was used for the first time in this study: cardiac arrest (ICD-10 code: I46) according to hospital discharge registry. Short-term increase in PM10 concentrations was associated with cardiac arrest. Future ecological studies of this type and their related discussions should perhaps concentrate more on precisely defined endpoints.Peer reviewe

Effects of Eyjafjallajökull volcanic ash on innate immune system responses and bacterial growth in vitro.

To access publisher's full text version of this article click on the hyperlink at the bottom of the pageOn 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions.We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20-100 µg/cm(2)), primary rat and human alveolar macrophages (5-20 µg/cm(2)), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria).Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides.These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals.National Institutes of Health (NIH) R01 HL079901 NIH RO1 HL096625 R21HL109589 National Science Foundation NSF-EAR0821615 National Institute of Environmental Health Sciences (NIEHS) through the University of Iowa Environmental Health Sciences Research Center NIEHS/NIH P30 ES005605 National Center for Research Resources, NI

Association Between Interstitial Lung Abnormalities and All-Cause Mortality.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.Interstitial lung abnormalities have been associated with lower 6-minute walk distance, diffusion capacity for carbon monoxide, and total lung capacity. However, to our knowledge, an association with mortality has not been previously investigated.To investigate whether interstitial lung abnormalities are associated with increased mortality.Prospective cohort studies of 2633 participants from the FHS (Framingham Heart Study; computed tomographic [CT] scans obtained September 2008-March 2011), 5320 from the AGES-Reykjavik Study (Age Gene/Environment Susceptibility; recruited January 2002-February 2006), 2068 from the COPDGene Study (Chronic Obstructive Pulmonary Disease; recruited November 2007-April 2010), and 1670 from ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints; between December 2005-December 2006).Interstitial lung abnormality status as determined by chest CT evaluation.All-cause mortality over an approximate 3- to 9-year median follow-up time. Cause-of-death information was also examined in the AGES-Reykjavik cohort.Interstitial lung abnormalities were present in 177 (7%) of the 2633 participants from FHS, 378 (7%) of 5320 from AGES-Reykjavik, 156 (8%) of 2068 from COPDGene, and in 157 (9%) of 1670 from ECLIPSE. Over median follow-up times of approximately 3 to 9 years, there were more deaths (and a greater absolute rate of mortality) among participants with interstitial lung abnormalities when compared with those who did not have interstitial lung abnormalities in the following cohorts: 7% vs 1% in FHS (6% difference [95% CI, 2% to 10%]), 56% vs 33% in AGES-Reykjavik (23% difference [95% CI, 18% to 28%]), and 11% vs 5% in ECLIPSE (6% difference [95% CI, 1% to 11%]). After adjustment for covariates, interstitial lung abnormalities were associated with a higher risk of death in the FHS (hazard ratio [HR], 2.7 [95% CI, 1.1 to 6.5]; P = .03), AGES-Reykjavik (HR, 1.3 [95% CI, 1.2 to 1.4]; P < .001), COPDGene (HR, 1.8 [95% CI, 1.1 to 2.8]; P = .01), and ECLIPSE (HR, 1.4 [95% CI, 1.1 to 2.0]; P = .02) cohorts. In the AGES-Reykjavik cohort, the higher rate of mortality could be explained by a higher rate of death due to respiratory disease, specifically pulmonary fibrosis.In 4 separate research cohorts, interstitial lung abnormalities were associated with a greater risk of all-cause mortality. The clinical implications of this association require further investigation.National Institutes of Health (NIH) T32 HL007633 Icelandic Research Fund 141513-051 Landspitali Scientific Fund A-2015-030 National Cancer Institute grant 1K23CA157631 NIH K08 HL097029 R01 HL113264 R21 HL119902 K25 HL104085 R01 HL116931 R01 HL116473 K01 HL118714 R01 HL089897 R01 HL089856 N01-AG-1-2100 HHSN27120120022C P01 HL105339 P01 HL114501 R01 HL107246 R01 HL122464 R01 HL111024 National Heart, Lung, and Blood Institute's Framingham Heart Study contract N01-HC-2519.5 GlaxoSmithKline NCT00292552 5C0104960 National Institute on Aging (NIA) grant 27120120022C NIA Intramural Research Program, Hjartavernd (the Icelandic Heart Association) Althingi (the Icelandic Parliament) NIA 27120120022

Gradual caldera collapse at Bárdarbunga volcano, Iceland, regulated by lateral magma outflow

Large volcanic eruptions on Earth commonly occur with a collapse of the roof of a crustal magma reservoir, forming a caldera. Only a few such collapses occur per century, and the lack of detailed observations has obscured insight into the mechanical interplay between collapse and eruption.We usemultiparameter geophysical and geochemical data to show that the 110-squarekilometer and 65-meter-deep collapse of Bárdarbunga caldera in 2014-2015 was initiated through withdrawal of magma, and lateral migration through a 48-kilometers-long dike, from a 12-kilometers deep reservoir. Interaction between the pressure exerted by the subsiding reservoir roof and the physical properties of the subsurface flow path explain the gradual, nearexponential decline of both collapse rate and the intensity of the 180-day-long eruption.</p

COPD in never smokers: results from the population-based burden of obstructive lung disease study.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.BACKGROUND: Never smokers comprise a substantial proportion of patients with COPD. Their characteristics and possible risk factors in this population are not yet well defined. METHODS: We analyzed data from 14 countries that participated in the international, population-based Burden of Obstructive Lung Disease (BOLD) study. Participants were aged ≥ 40 years and completed postbronchodilator spirometry testing plus questionnaires about respiratory symptoms, health status, and exposure to COPD risk factors. A diagnosis of COPD was based on the postbronchodilator FEV₁/FVC ratio, according to current GOLD (Global Initiative for Obstructive Lung Disease) guidelines. In addition to this, the lower limit of normal (LLN) was evaluated as an alternative threshold for the FEV₁/FVC ratio. RESULTS: Among 4,291 never smokers, 6.6% met criteria for mild (GOLD stage I) COPD, and 5.6% met criteria for moderate to very severe (GOLD stage II+) COPD. Although never smokers were less likely to have COPD and had less severe COPD than ever smokers, never smokers nonetheless comprised 23.3% (240/1,031) of those classified with GOLD stage II+ COPD. This proportion was similar, 20.5% (171/832), even when the LLN was used as a threshold for the FEV₁/FVC ratio. Predictors of COPD in never smokers include age, education, occupational exposure, childhood respiratory diseases, and BMI alterations. CONCLUSION: This multicenter international study confirms previous evidence that never smokers comprise a substantial proportion of individuals with COPD. Our data suggest that, in addition to increased age, a prior diagnosis of asthma and, among women, lower education levels are associated with an increased risk for COPD among never smokers.ALTANA Aventis AstraZeneca Boehringer-Ingleheim Chiesi GlaxoSmithKline Merck Novartis Pfizer Inc Schering-Plough Sunovion Pharmaceuticals Inc University of Kentucky Schering Plough Sepracor AstraZeneca, Spai