256 research outputs found
The Gamma-Ray Detected Narrow-Line Seyfert 1 Galaxy 1H 0323+342: Swift Monitoring and Suzaku Spectroscopy
As a radio-loud narrow-line Seyfert 1 galaxy (NLS1) detected by Fermi/LAT in
GeV -rays, 1H 0323+342 is a remarkable Active Galactic Nucleus (AGN)
showing properties characteristic of both NLS1s and blazars. Here we present
results of simultaneous X-ray and UV/optical monitoring observations on 1H
0323+342 taken with the UV/Optical Telescope (UVOT) and X-ray Telescope (XRT)
onboard the Swift satellite over six years from 2006. Overall, the object
showed statistically correlated variations in both the UV and X-ray bands on
timescales of years as well as on timescales of days. A deep Suzaku observation
reveals X-ray variability on timescales as short as a few tens of thousand
seconds, and an X-ray spectrum typical of Seyfert galaxies. The broad-band
spectral energy distribution, for which the data of UV and X-ray observations
taken on 2009 July 26-27 were used, can be well modeled with a simple one-zone
leptonic jet model plus accretion disk/corona emission. The latter is
predominantly responsible for the UV/optical and X-ray (0.3-10 keV) emission
and their observed variations. The correlated UV-X-ray variability on the
timescale of days is consistent with reprocessing of the X-ray radiation by the
accretion disk. The shortest timescale and large normalized excess variance of
the X-ray variability detected with Suzaku suggest a relatively small black
hole mass of the order of , consistent with the estimation based
on the broad H line in the optical.Comment: 38 pages, 12 figures, in press, accepted by AJ (first submitted on
2014 July 7th
Identification of a New -ray-emitting narrow-line Seyfert 1 Galaxy, at Redshift
We report on the identification of a new -ray-emitting narrow-line
Seyfert 1 (NLS1) galaxy, SDSS J122222.55+041315.7, which increases the number
of known objects of this remarkable but rare type of active galactic nuclei
(AGN) to seven. Its optical spectrum, obtained in the Sloan Digital Sky
Survey-Baryon Oscillation Spectroscopic Survey, reveals a broad H
emission line with a width (FWHM) of 1734104 km s. This, along with
strong optical Fe II multiplets [] and a weak [O III] emission line, makes the object a typical NLS1. On the other hand, the
source exhibits a high radio brightness temperature, rapid infrared
variability, and a flat X-ray spectrum extending up to 200 keV. It is
associated with a luminous -ray source detected significantly with {\it
Fermi}/LAT. Correlated variability with other wavebands has not yet been
tested. The spectral energy distribution can be well modelled by a one-zone
leptonic jet model. This new member is by far the most distant
-ray-emitting NLS1, at a redshift of .Comment: 5 pages, published on MNRA
A Novel Semisupervised Contrastive Regression Framework for Forest Inventory Mapping with Multisensor Satellite Data
Accurate mapping of forests is critical for forest management and carbon
stocks monitoring. Deep learning is becoming more popular in Earth Observation
(EO), however, the availability of reference data limits its potential in
wide-area forest mapping. To overcome those limitations, here we introduce
contrastive regression into EO based forest mapping and develop a novel
semisupervised regression framework for wall-to-wall mapping of continuous
forest variables. It combines supervised contrastive regression loss and
semi-supervised Cross-Pseudo Regression loss. The framework is demonstrated
over a boreal forest site using Copernicus Sentinel-1 and Sentinel-2 imagery
for mapping forest tree height. Achieved prediction accuracies are strongly
better compared to using vanilla UNet or traditional regression models, with
relative RMSE of 15.1% on stand level. We expect that developed framework can
be used for modeling other forest variables and EO datasets
Detection of a parsec-scale jet in a radio-quiet narrow-line Seyfert 1 galaxy with highly accreting supermassive black hole
The jet in active galactic nuclei (AGN) is a key ingredient in understanding the co-evolution of galaxies and their central supermassive black holes (SMBHs). Unfortunately, the mechanism of jet launching and collimation is still elusive. The observational evidence of decreasing radio loudness with increasing Eddington ratio implies that the jet should be coupled with the accretion process. To further explore the relationship between the jet and accretion, it is necessary to extend our knowledge of the jet to an extreme end of the Eddington ratio distribution of AGN. Using Very Long Baseline Array (VLBA), we report the detection of the parsec-scale radio structure in Mrk 335, a radio-quiet narrow-line Seyfert 1 galaxy with an Eddington ratio close to/above unity. The VLBA image at 1.5 GHz reveals an elongated structure extending ∼20 pc in north-south direction with a peak flux density of 1.98 \ub1 0.05 mJy beam-1 and radio brightness temperatures as high as 6
7 107 K. This feature provides a strong evidence of a parsec-scale (bipolar) jet launched from a highly accreting SMBH. We discuss the result by comparing Mrk 335 with other highly accreting systems, e.g. Galactic black holes and tidal disruption events, and recall the discovery of collimated corona in the vicinity of SMBH in Mrk 335 by previous X-ray observations, whose relation to the parsec-scale radio jet should be explored by future simultaneous X-ray spectroscopy and high resolution radio observations
Manganese oxide electrode with excellent electrochemical performance for sodium ion batteries by pre-intercalation of K and Na ions
Materials with a layered structure have attracted tremendous attention because of their unique properties. The ultrathin nanosheet structure can result in extremely rapid intercalation/de-intercalation of Na ions in the charge-discharge progress. Herein, we report a manganese oxide with pre-intercalated K and Na ions and having flower-like ultrathin layered structure, which was synthesized by a facile but efficient hydrothermal method under mild condition. The pre-intercalation of Na and K ions facilitates the access of electrolyte ions and shortens the ion diffusion pathways. The layered manganese oxide shows ultrahigh specific capacity when it is used as cathode material for sodium-ion batteries. It also exhibits excellent stability and reversibility. It was found that the amount of intercalated Na ions is approximately 71% of the total charge. The prominent electrochemical performance of the manganese oxide demonstrates the importance of design and synthesis of pre-intercalated ultrathin layered materials
The ratio of systolic and diastolic pressure is associated with carotid and femoral atherosclerosis
BackgroundAlthough the impact of hypertension on carotid intima-media thickness (IMT) and plaques has been well established, its association with femoral IMT and plaques has not been extensively examined. In addition, the role of the ratio of systolic and diastolic pressure (SDR) in the subclinical atherosclerosis (AS) risk remains unknown. We assessed the relationship between SDR and carotid and femoral AS in a general population.MethodsA total of 7,263 participants aged 35–74 years enrolled from January 2019 to June 2021 in a southeast region of China were included in a cross-sectional study. Systolic and diastolic blood pressure (SBP and DBP) were used to define SDR. Ultrasonography was applied to assess the AS, including thickened IMT (TIMT) and plaque in the carotid and femoral arteries. Logistic regression and restricted cubic spline (RCS) models were the main approaches.ResultsThe prevalence of TIMT, plaque, and AS were 17.3%, 12.4%, and 22.7% in the carotid artery; 15.2%, 10.7%, and 19.5% in the femoral artery; and 23.8%, 17.9% and 30.0% in either the carotid or femoral artery, respectively. Multivariable logistic regression analysis found a significant positive association between high-tertile SDR and the higher risk of overall TIMT (OR = 1.28, 95% CI = 1.10–1.49), plaques (OR = 1.36, 95%CI = 1.16–1.61), or AS (OR = 1.36, 95% CI = 1.17–1.57), especially in the carotid artery. RCS analysis further revealed the observed positive associations were linear. Further analyses showed that as compared to the low-tertile SDR and non-hypertension group, high-tertile SDR was associated with increased risks of overall and carotid TIMT, plaques, or AS in both groups with or without hypertension.ConclusionsSDR is related to a higher risk of subclinical AS, regardless of hypertension or not, suggesting that as a readily obtainable index, SDR can contribute to providing additional predictive value for AS
Multilaboratory assessment of Epstein-Barr virus serologic assays: the case for standardization
IgA antibodies targeting Epstein-Barr virus (EBV) have been proposed for screening for nasopharyngeal carcinoma (NPC). However, methods differ, and the antigens used in these assays differ considerably between laboratories. To enable formal comparisons across a range of established EBV serology assays, we created a panel of 66 pooled serum samples and 66 pooled plasma samples generated from individuals with a broad range of IgA antibody levels. Aliquots from these panels were distributed to six laboratories and were tested by 26 assays measuring antibodies against VCA, EBNA1, EA-EBNA1, Zta, or EAd antigens. We estimated the correlation between assay pairs using Spearman coefficients (continuous measures) and percentages of agreement (positive versus negative, using predefined positivity cutoffs by each assay developer/manufacturer). While strong correlations were observed between some assays, considerable differences were also noted, even for assays that targeted the same protein. For VCA-IgA assays in serum, two distinct clusters were identified, with a median Spearman coefficient of 0.41 (range, 0.20 to 0.66) across these two clusters. EBNA1-IgA assays in serum grouped into a single cluster with a median Spearman coefficient of 0.79 (range, 0.71 to 0.89). Percentages of agreement differed broadly for both VCA-IgA (12% to 98%) and EBNA1-IgA (29% to 95%) assays in serum. Moderate-to-strong correlations were observed across assays in serum that targeted other proteins (correlations ranged from 0.44 to 0.76). Similar results were noted for plasma. We conclude that standardization of EBV serology assays is needed to allow for comparability of results obtained in different translational research studies across laboratories and populations
Safety and immunological responses to human mesenchymal stem cell therapy in difficult-to-treat HIV-1-infected patients
HAART largely decreases morbidity and mortality in chronic HIV-1-infected patients, but immune nonresponders (INRs) with full viral suppression still fail to reverse the immune deficiency. This study evaluated the safety and immunological responses of human umbilical cord mesenchymal stem cell (MSC) therapy in HIV-1-infected INRs
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