2,057 research outputs found
An analysis of interplanetary solar radio emissions associated with a coronal mass ejection
Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma
that may cause severe geomagnetic storms if Earth-directed. Here we report a
rare instance with comprehensive in situ and remote sensing observa- tions of a
CME combining white-light, radio, and plasma measurements from four different
vantage points. For the first time, we have successfully applied a radio
direction-finding technique to an interplanetary type II burst detected by two
identical widely separated radio receivers. The derived locations of the type
II and type III bursts are in general agreement with the white light CME recon-
struction. We find that the radio emission arises from the flanks of the CME,
and are most likely associated with the CME-driven shock. Our work demon-
strates the complementarity between radio triangulation and 3D reconstruction
techniques for space weather applications
Radon: a universal baseline indicator at sites with contrasting physical settings
The primary goal of World Meteorological Organisation Global Atmosphere Watch (WMOāGAW) baseline stations is systematic global monitoring of chemical composition of the atmosphere, requiring a reliable, consistent and unambiguous approach for the identification of baseline air. Premier stations in the GAW baseline network span a
broad range of physical settings, from remote marine to highāaltitude continental sites, necessitating carefully tailored
siteāspecific requirements for baseline sampling, data selection, and analysis. Radonā222 is a versatile and unambiguous terrestrial tracer, widelyāused in transport and mixing studies. Since the majority of anthropogenic pollution sources also have terrestrial origins, radon has become a popular addition to the ābaseline selection
toolkitā at numerous GAW stations as a proxy for āpollution potentialā. In the past, detector performance and postprocessing
methods necessitated the adoption of a relaxed (e.g. 100 mBq mā3) radon threshold for minimal terrestrial influence, intended to be used in conjunction with other baseline criteria and analysis procedures, including wind speed, wind direction, particle number, outlier rejection and filtering. However, recent improvements in detector sensitivity, stability and postāprocessing procedures have reduced detection limits below 10 mBq mā3 at Cape Grim and to ļ¾25 mBq mā3 at other baseline stations. Consequently, for suitably sensitive instruments (such as the ANSTO designed and built twoāfilter dualāflowāloop detectors), radon concentrations alone can be used to unambiguously identify air masses that have been removed from terrestrial sources (at altitude or over ice), or in equilibrium
with the ocean surface, for periods of >2ā3 weeks (radon ā¤ 40 mBq mā3). Potentially, radon observations alone can thus provide a consistent and universal (site independent) means for baseline identification. Furthermore, for continental sites with complex topography and meteorology, where true ābaselineā conditions may never
occur, radon can be used to indicate the least terrestriallyāperturbed air masses, and provide a means by which to apply limits to the level of āacceptable terrestrial influenceā for a given application. We demonstrate the efficacy of the radonābased selection at a range of sites in contrasting physical settings, including: Cape Grim (Tasmania), Cape Point (South Africa), Mauna Loa (Hawaii), Jungfraujoch (Switzerland) and Schneefernerhaus (Germany).Bureau of Meteorology and CSIRO Oceans and Atmosphere,Climate Science Centre
Towards a universal ābaselineā characterisation of air masses for high- and low-altitude observing stations using Radon-222
We demonstrate the ability of atmospheric radon concentrations to reliably and unambiguously identify local and
remote terrestrial influences on an air mass, and thereby the potential for alteration of trace gas composition by
anthropogenic and biogenic processes. Based on high accuracy (lower limit of detection 10ā40 mBq mā3), high temporal
resolution (hourly) measurements of atmospheric radon concentration we describe, apply and evaluate a simple two-step
method for identifying and characterising constituent mole fractions in baseline air. The technique involves selecting a
radon-based threshold concentration to identify the ācleanestā (least terrestrially influenced) air masses, and then
performing an outlier removal step based on the distribution of constituent mole fractions in the identified clean air
masses. The efficacy of this baseline selection technique is tested at three contrasting WMO GAW stations: Cape Grim (a
coastal low-altitude site), Mauna Loa (a remote high-altitude island site), and Jungfraujoch (a continental high-altitude
site). At Cape Grim and Mauna Loa the two-step method is at least as effective as more complicated methods employed to
characterise baseline conditions, some involving up to nine steps. While it is demonstrated that Jungfraujoch air masses
rarely meet the baseline criteria of the more remote sites, a selection method based on a variable monthly radon threshold
is shown to produce credible ānear baselineā characteristics. The seasonal peak-to-peak amplitude of recent monthly
baseline CO2 mole fraction deviations from the long-term trend at Cape Grim, Mauna Loa and Jungfraujoch are estimated
to be 1.1, 6.0 and 8.1 ppm, respectively
A Novel Unsupervised Method to Identify Genes Important in the Anti-viral Response: Application to Interferon/Ribavirin in Hepatitis C Patients
Background: Treating hepatitis C with interferon/ribavirin results in a varied response in terms of decrease in viral titer and ultimate outcome. Marked responders have a sharp decline in viral titer within a few days of treatment initiation, whereas in other patients there is no effect on the virus (poor responders). Previous studies have shown that combination therapy modifies expression of hundreds of genes in vitro and in vivo. However, identifying which, if any, of these genes have a role in viral clearance remains challenging. Aims: The goal of this paper is to link viral levels with gene expression and thereby identify genes that may be responsible for early decrease in viral titer. Methods: Microarrays were performed on RNA isolated from PBMC of patients undergoing interferon/ribavirin therapy. Samples were collected at pre-treatment (day 0), and 1, 2, 7, 14 and 28 days after initiating treatment. A novel method was applied to identify genes that are linked to a decrease in viral titer during interferon/ribavirin treatment. The method uses the relationship between inter-patient gene expression based proximities and inter-patient viral titer based proximities to define the association between microarray gene expression measurements of each gene and viral-titer measurements. Results: We detected 36 unique genes whose expressions provide a clustering of patients that resembles viral titer based clustering of patients. These genes include IRF7, MX1, OASL and OAS2, viperin and many ISG's of unknown function. Conclusion: The genes identified by this method appear to play a major role in the reduction of hepatitis C virus during the early phase of treatment. The method has broad utility and can be used to analyze response to any group of factors influencing biological outcome such as antiviral drugs or anti-cancer agents where microarray data are available. Ā© 2007 Brodsky et al
Theory of current-driven motion of Skyrmions and spirals in helical magnets
We study theoretically the dynamics of the spin textures, i.e., Skyrmion
crystal (SkX) and spiral structure (SS), in two-dimensional helical magnets
under external current. By numerically solving the Landau-Lifshitz-Gilbert
equation, it is found that (i) the critical current density of the motion is
much lower for SkX compared with SS in agreement with the recent experiment,
(ii) there is no intrinsic pinning effect for SkX and the deformation of the
internal structure of Skyrmion reduces the pinning effect dramatically, (iii)
the Bragg intensity of SkX shows strong time-dependence as can be observed by
neutron scattering experiment.Comment: 4 pages, 3 figure
Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars
A knowledge of stellar ages is crucial for our understanding of many
astrophysical phenomena, and yet ages can be difficult to determine. As they
become older, stars lose mass and angular momentum, resulting in an observed
slowdown in surface rotation. The technique of 'gyrochronology' uses the
rotation period of a star to calculate its age. However, stars of known age
must be used for calibration, and, until recently, the approach was untested
for old stars (older than 1 gigayear, Gyr). Rotation periods are now known for
stars in an open cluster of intermediate age (NGC 6819; 2.5 Gyr old), and for
old field stars whose ages have been determined with asteroseismology. The data
for the cluster agree with previous period-age relations, but these relations
fail to describe the asteroseismic sample. Here we report stellar evolutionary
modelling, and confirm the presence of unexpectedly rapid rotation in stars
that are more evolved than the Sun. We demonstrate that models that incorporate
dramatically weakened magnetic braking for old stars can---unlike existing
models---reproduce both the asteroseismic and the cluster data. Our findings
might suggest a fundamental change in the nature of ageing stellar dynamos,
with the Sun being close to the critical transition to much weaker magnetized
winds. This weakened braking limits the diagnostic power of gyrochronology for
those stars that are more than halfway through their main-sequence lifetimes.Comment: 25 pages, 3 figures in main paper, 6 extended data figures, 1 table.
Published in Nature, January 2016. Please see https://youtu.be/O6HzYgP5uyc
for a video description of the resul
Bronchial mucosal inflammation and illness severity in response to experimental rhinovirus infection in COPD
Background Respiratory viral infection causes chronic obstructive pulmonary disease (COPD) exacerbations. We previously reported increased bronchial mucosa eosinophil and neutrophil inflammation in patients with COPD experiencing naturally occurring exacerbations. But it is unclear whether virus per se induces bronchial mucosal inflammation, nor whether this relates to exacerbation severity. Objectives We sought to determine the extent and nature of bronchial mucosal inflammation following experimental rhinovirus (RV)-16āinduced COPD exacerbations and its relationship to disease severity. Methods Bronchial mucosal inflammatory cell phenotypes were determined at preinfection baseline and following experimental RV infection in 17 Global Initiative for Chronic Obstructive Lung Disease stage II subjects with COPD and as controls 20 smokers and 11 nonsmokers with normal lung function. No subject had a history of asthma/allergic rhinitis: all had negative results for aeroallergen skin prick tests. Results RV infection increased the numbers of bronchial mucosal eosinophils and neutrophils only in COPD and CD8+ T lymphocytes in patients with COPD and nonsmokers. Monocytes/macrophages, CD4+ T lymphocytes, and CD20+ B lymphocytes were increased in all subjects. At baseline, compared with nonsmokers, subjects with COPD and smokers had increased numbers of bronchial mucosal monocytes/macrophages and CD8+ T lymphocytes but fewer numbers of CD4+ T lymphocytes and CD20+ B lymphocytes. The virus-induced inflammatory cells in patients with COPD were positively associated with virus load, illness severity, and reductions in lung function. Conclusions Experimental RV infection induces bronchial mucosal eosinophilia and neutrophilia only in patients with COPD and monocytes/macrophages and lymphocytes in both patients with COPD and control subjects. The virus-induced inflammatory cell phenotypes observed in COPD positively related to virus load and illness severity. Antiviral/anti-inflammatory therapies could attenuate bronchial inflammation and ameliorate virus-induced COPD exacerbations
Cigarette smoke exposure inhibits extracellular MMP-2 (gelatinase A) activity in human lung fibroblasts
BACKGROUND: Exposure to cigarette smoke is considered a major risk factor for the development of lung diseases, since its causative role has been assessed in the induction and maintenance of an inflamed state in the airways. Lung fibroblasts can contribute to these processes, due to their ability to produce proinflammatory chemotactic molecules and extracellular matrix remodelling proteinases. Among proteolytic enzymes, gelatinases A and B have been studied for their role in tissue breakdown and mobilisation of matrix-derived signalling molecules. Multiple reports linked gelatinase deregulation and overexpression to the development of inflammatory chronic lung diseases such as COPD. METHODS: In this study we aimed to determine variations in the gelatinolytic pattern of human lung fibroblasts (HFL-1 cell line) exposed to cigarette smoke extract (CSE). Gelatinolytic activity levels were determined by using gelatin zymography for the in-gel detection of the enzymes (proenzyme and activated forms), and the subsequent semi-quantitative densitometric evaluation of lytic bands. Expression of gelatinases was evaluated also by RT-PCR, zymography of the cell lysates and by western blotting. RESULTS: CSE exposure at the doses used (1ā10%) did not exert any significant cytotoxic effects on fibroblasts. Zymographic analysis showed that CSE exposure resulted in a linear decrease of the activity of gelatinase A. Control experiments allowed excluding a direct inhibitory effect of CSE on gelatinases. Zymography of cell lysates confirmed the expression of MMP-2 in all conditions. Semi-quantitative evaluation of mRNA expression allowed assessing a reduced transcription of the enzyme, as well as an increase in the expression of TIMP-2. Statistical analyses showed that the decrease of MMP-2 activity in conditioned media reached the statistical significance (p = 0.0031 for 24 h and p = 0.0012 for 48 h), while correlation analysis showed that this result was independent from CSE cytotoxicity (p = 0.7833 for both exposures). CONCLUSION: Present work describes for the first time that, apart well characterized proinflammatory responses, human lung fibroblasts may react to CSE with a significant reduction of extracellular MMP-2 lytic activity. Therefore, fibroblasts may actively participate to the alteration of the proteolysis/antiproteolysis balance, which reflects the defective repair of the extracellular matrix. Such event should provide a further contribution to the maintenance of the inflamed state in the lungs
Associations among the parentāadolescent relationship, aggression and delinquency in different ethnic groups: a replication across two Dutch samples
Background: The aim of the present study is to examine whether the patterns of association between the quality of the parent-adolescent relationship on the one hand, and aggression and delinquency on the other hand, are the same for boys and girls of Dutch and Moroccan origin living in the Netherlands. Since inconsistent results have been found previously, the present study tests the replicability of the model of associations in two different Dutch samples of adolescents. Method: Study 1 included 288 adolescents (M age = 14.9, range 12-17 years) all attending lower secondary education. Study 2 included 306 adolescents (M age = 13.2, range = 12-15 years) who were part of a larger community sample with oversampling of at risk adolescents. Results: Multigroup structural analyses showed that neither in Study 1 nor in Study 2 ethnic or gender differences were found in the patterns of associations between support, autonomy, disclosure, and negativity in the parent-adolescent relationship and aggression and delinquency. The patterns were largely similar for both studies. Mainly negative quality of the relationship in both studies was found to be strongly related to both aggression and delinquency. Discussion: Results show that family processes that affect adolescent development, show a large degree of universality across gender and ethnicity
Utility of a buccal swab point-of-care test for the IFNL4 genotype in the era of direct acting antivirals for hepatitis C virus.
BACKGROUND: The CC genotype of the IFNL4 gene is known to be associated with increased Hepatitis C (HCV) cure rates with interferon-based therapy and may contribute to cure with direct acting antivirals. The GenedriveĀ® IFNL4 is a CE marked Point of Care (PoC) molecular diagnostic test, designed for in vitro diagnostic use to provide rapid, real-time detection of IFNL4 genotype status for SNP rs12979860. METHODS: 120 Participants were consented to a substudy comparing IFNL4 genotyping results from a buccal swab analysed on the GenedriveĀ® platform with results generated using the Affymetix UK Biobank array considered to be the gold standard. RESULTS: Buccal swabs were taken from 120 participants for PoC IFNL4 testing and a whole blood sample for genetic sequencing. Whole blood genotyping vs. buccal swab PoC testing identified 40 (33%), 65 (54%), and 15 (13%) had CC, CT and TT IFNL4 genotype respectively. The Buccal swab PoC identified 38 (32%) CC, 64 (53%) CT and 18 (15%) TT IFNL4 genotype respectively. The sensitivity and specificity of the buccal swab test to detect CC vs non-CC was 90% (95% CI 76-97%) and 98% (95% CI 91-100%) respectively. CONCLUSIONS: The buccal swab test was better at correctly identifying non-CC genotypes than CC genotypes. The high specificity of the GenedriveĀ® assay prevents CT/TT genotypes being mistaken for CC, and could avoid patients being identified as potentially 'good responders' to interferon-based therapy
- ā¦