Abstract
Hot dust-obscured galaxies (DOGs) are hyperluminous (L8–1000 μm > 1013 L⊙) infrared galaxies with extremely high (up to hundreds of K) dust temperatures. The sources powering both their ...extremely high luminosities and dust temperatures are thought to be deeply buried and rapidly accreting supermassive black holes (SMBHs). Hot DOGs could therefore represent a key evolutionary phase in which the SMBH growth peaks. X-ray observations can be used to study their obscuration levels and luminosities. In this work, we present the X-ray properties of the 20 most luminous (Lbol ≳ 1014 L⊙) known hot DOGs at z = 2–4.6. Five of them are covered by long-exposure (10–70 ks) Chandra and XMM–Newton observations, with three being X-ray detected, and we study their individual properties. One of these sources (W0116−0505) is a Compton-thick candidate, with column density NH = (1.0–1.5) × 1024 cm−2 derived from X-ray spectral fitting. The remaining 15 hot DOGs have been targeted by a Chandra snapshot (3.1 ks) survey. None of these 15 are individually detected; therefore, we applied a stacking analysis to investigate their average emission. From hardness ratio analysis, we constrained the average obscuring column density and intrinsic luminosity to be log NH (cm−2) > 23.5 and LX ≳ 1044 erg s−1, which are consistent with results for individually detected sources. We also investigated the LX–L6 μm and LX–Lbol relations, finding hints that hot DOGs are typically X-ray weaker than expected, although larger samples of luminous obscured quasi-stellar objects are needed to derive solid conclusions.
Background
Obesity accelerates and exacerbates the age-related changes on muscle function and exercise capacity. In addition, the middle-aged population is often overlooked when talking about the ...prevention of sarcopenia. This study investigated the effects of exercise alone or in combination with a high-protein diet on muscle function and physical fitness in middle-aged obese adults.
Materials and methods
Sixty-nine middle-aged (501–64 years old) obese adults were randomly assigned to one of the following groups: control group (C; n=23), exercise group (E; n=23) or exercise plus high-protein group (EP; n=23). Individuals within the E and EP groups received 12 weeks of exercise training; whereas, the individuals in the EP group also received a highprotein diet intervention (1.6g/kg/day). Individuals within the C group were asked to maintain their lifestyle for 12 weeks. Participants were evaluated before and after the intervention. Outcome measures included maximal exercise capacity, muscle function and functional physical performance. Analysis of covariance was used to determine the effects of the intervention.
Results
After the intervention, the E and EP groups had greater maximal work rate, peak oxygen consumption, and muscle power during muscle contractions at 180°/sec than that in the C group (P<0.05). The EP group, but not the E group, showed significant improvement in the sit-to-stand test and climbing stairs test than the C group after the intervention (P<0.05). Within group comparisons showed that the anaerobic threshold only increased in the EP group (+12% from pre-test).
Conclusions
For middle-aged obese adults, exercise with a high-protein diet not only improved muscle power and exercise capacity but also enhanced their functional physical performance.
A fundamental question of earthquake science is what produces damaging high‐frequency ground motion, with the classic Brune‐Haskell model postulating that abrupt fault slip causes it. However, even ...when amended with heterogeneous rupture, the model fails to explain observations of different sized repeating earthquakes and has challenges explaining high‐frequency radiation patterns. We propose an additional cause for high‐frequency earthquake spectra from elastic collisions of structures within a rupturing fault zone. The collision spectrum is set by an impact contact time proportional to the size of colliding structures so that spectra depend on fundamentally different physical parameters compared with slip models. When added to standard models, collisions can reconcile the discrepant observations since the size, shape, and orientation of structures vary between different fault zones but remain constant within a fault segment. High‐frequency earthquake ground motions and damage may therefore be an outgrowth of fault‐zone structure rather than sudden initiation of slip.
Plain Language Summary
Why do earthquakes damage buildings? Many buildings are damaged most heavily by fast, jerky ground motion rather than the longer duration rolling motions that contain most of the earthquake energy. Despite the importance of these fast, jerky motions, most frictional models for earthquakes generally underpredict how strong they are, even when heterogeneous friction and realistic roughness are accounted for. We propose that collisions of structures as they attempt to slide past each other during an earthquake may also create jerky ground motion. We find that the ground motion from collisions depends mostly on the size of the structures and does not depend on stresses within the Earth and thus gives a very different interpretation of what causes the most damaging ground motions. When incorporated with standard frictional models, the collision model explains various observations that are otherwise difficult to explain, including why some earthquakes appear to be identical in time but with larger amplitudes, why faults that have had many earthquakes have less damaging ground motions, and why earthquake damage is observed to occur more uniformly than previously predicted.
Key Points
Collisions of structures within fault zones cause high‐frequency earthquake ground motion
The physics of elastic impact predicts that collisions depend on different physical parameters as compared with frictional fault slip
Accounting for elastic impact ground motion can explain stress drop and radiation pattern observations
This study aimed to estimate the associations between job insecurity and symptoms of anxiety and depression among U.S. young adults amidst the COVID-19 pandemic.
We analyzed data on young adults aged ...18–26 years from June 15 to June 30, 2020, from the weekly, cross-sectional Household Pulse Survey (n = 4,852) conducted by the U.S. Census Bureau. Two job insecurity measures and four anxiety and depression measures were analyzed using multivariable Poisson regression models adjusting for age, sex, race/ethnicity, education, and marital status.
Fifty-nine percent of participants experienced direct or household employment loss since the start of the COVID-19 pandemic, and 38% were expected to experience direct or household employment loss in the coming 4 weeks. Recent direct or household employment loss and expected direct or household employment loss, among participants who did not experience recent employment loss, were associated with a greater risk of poor mental health on all four measures.
U.S. young adults experience a significant mental health burden as a result of job insecurity amidst the COVID-19 pandemic.
The aim of this study was to chemically characterize the fine particulate matter (PM2.5) at a subtropical forest in East Asia under the influences of anthropogenic and biogenic sources and a complex ...topographic setting. Four seasonal campaigns were conducted at the Xitou Experimental Forest in central Taiwan from the winter of 2013 to the autumn of 2014. The results indicated that the ambient levels and chemical features of PM2.5 exhibited pronounced seasonal variations. Non-sea-salt sulfate (nss-SO42-) constituted the major component of PM2.5, followed by ammonium (NH4+) and nitrate (NO3−) during winter, summer and autumn. However, it was revealed that the mass fraction of NO3− increased to be comparable with that of nss-SO42- in springtime. The mass contribution of secondary organic carbon (SOC) to PM2.5 peaked in summer (13.2%), inferring the importance of enhanced photo-oxidation reactions in SOC formation. Diurnal variations of O3 and SO2 coincided with each other, suggesting the transport of aged pollutants from distant sources, whereas CO and NOx were shown to be under the influences of both local and regional sources. Notably high sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) were observed, which were 0.93 ± 0.05 and 0.39 ± 0.20, respectively. Precursor gases (i.e. SO2 and NOx) could be converted to sulfate and nitrate during the transport by the uphill winds. Furthermore, due to the high relative humidity at Xitou, enhanced aqueous-phase and/or heterogeneous reactions could further contribute to the formation of sulfate and nitrate at the site. This study demonstrated the significant transport of urban pollutants to a subtropical forest by the mountain-valley circulations as well as the long-range transport from regional sources, whereas the implications of which for regional climate change necessitated further investigation.
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•Distinct seasonal variations are observed in PM2.5 composition at forest site.•Notably high nitrate concentrations (6.19 μg/m3) are found in spring.•Significant secondary organic carbon (up to13.2% in summer) in PM2.5•The sulfur and nitrogen oxidation ratios are 0.93 and 0.39
Four measurement campaigns were conducted at Xitou Experimental Forest in central Taiwan to characterize the fine particulate matter (PM2.5) at a high-elevation subtropical forest in East Asia where pollutants were effectively transported by mountain-valley circulations, and long-range transport from regional sources.
A promising accelerator light source mechanism called steady‐state microbunching (SSMB) is being actively studied. With the combination of strong coherent radiation from microbunching and high ...repetition rate of a storage ring, high‐average‐power narrow‐band radiation can be anticipated from an SSMB storage ring, with wavelengths ranging from THz to soft X‐ray. Such a novel light source could provide new opportunities for accelerator photon science like high‐resolution angle‐resolved photoemission spectroscopy and industrial applications like extreme ultraviolet (EUV) lithography. In this paper, a theoretical and numerical study of the average and statistical properties of coherent radiation from SSMB are presented. The results show that 1 kW average‐power quasi‐continuous‐wave EUV radiation can be obtained from an SSMB ring provided that an average current of 1 A and a microbunch train with bunch length of 3 nm can be formed at the radiator which is assumed to be an undulator. Together with the narrow‐band feature, the EUV photon flux can reach 6 × 1015 photons s−1 within a 0.1 meV energy bandwidth, which is three orders of magnitude higher than that in a conventional synchrotron source and is appealing for fundamental condensed matter physics and other research. In this theoretical investigation, we have generalized the definition and derivation of the transverse form factor of an electron beam which can quantify the impact of its transverse size on coherent radiation. In particular, it has been shown that the narrow‐band feature of SSMB radiation is strongly correlated with the finite transverse electron beam size. Considering the pointlike nature of electrons and quantum nature of radiation, the coherent radiation fluctuates from microbunch to microbunch, or for a single microbunch from turn to turn. Some important results concerning the statistical properties of SSMB radiation are presented, with a brief discussion on its potential applications, for example the beam diagnostics. The presented work is of value for the development of SSMB to better serve potential synchrotron radiation users. In addition, this also sheds light on understanding the radiation characteristics of free‐electron lasers, coherent harmonic generation, etc.
The radiation properties of a novel high‐power accelerator light source are presented. Potential applications include high‐resolution angle‐resolved photoemission spectroscopy and extreme ultraviolet lithography.
Background
Childhood asthma comprises different phenotypes with complex pathophysiology. Different asthma phenotypes evoke various clinical symptoms and vary in their responses to treatments.
Methods
...We applied k‐means clustering algorithm of twelve objective laboratory tests among 351 asthmatic children enrolled in the Taiwanese Consortium of Childhood Asthma Study (TCCAS). We constructed gene expression profiles of peripheral blood mononuclear cells (PBMC) from children with different asthma phenotypes.
Results
Five distinct phenotypes of childhood asthma were identified and can be characterized by either eosinophil‐predominant or neutrophil‐predominant inflammatory characteristics. In the gene expression profile analysis, significant differences were noted for neutrophil‐predominant asthma, compared with samples from all the other asthma phenotypes. The vast majority of the differentially expressed genes in neutrophil‐predominant asthma was associated with corticosteroid response. From an independent inhaled corticosteroid (ICS) response cohort, we also found neutrophils could be activated in this severe asthma phenotype and neutrophil‐predominant asthma may be associated with corticosteroid nonresponsiveness.
Conclusion
Phenotype clustering of childhood asthma can be helpful to identify clinically relevant patients and reveal different inflammatory characteristics in asthmatic children. Neutrophil‐predominant asthma is the most severe asthma phenotype with poor corticosteroid response. Gene expression profile of different asthma phenotypes not only improve our knowledge of childhood asthma, but also can guide asthma precision medicine.
Neutrophil‐predominant asthma is the most severe asthma phenotype with poor corticosteroid response. Five distinct phenotypes of childhood asthma identified in this study with differences in lung function, symptom frequency, healthcare utilization, percentages of eosinophils and neutrophils in peripheral blood, and serum IgE. Gene expression signature in PBMC constitutes an easier way to objectively identify corticosteroid‐resistant asthma in clinical settings.
Developing a three‐dimensional (3D) lithofacies model from boreholes is critical for providing a coherent understanding of complex subsurface geology, which is essential for groundwater studies. This ...study aims to introduce a new geostatistical method—interval kriging—to efficiently conduct 3D borehole‐based lithological modeling with sand/non‐sand binary indicators. Interval kriging is a best linear unbiased estimator for irregular interval supports. Interval kriging considers 3D anisotropies between two orthogonal components—a horizontal plane and a vertical axis. A new 3D interval semivariogram is developed. To cope with the nonconvexity of estimation variance, the minimization of estimation variance is regulated with an additional regularization term. The minimization problem is solved by a global‐local genetic algorithm embedded with quadratic programming and Brent's method to obtain kriging weights and kriging length. Four numerical and real‐world case studies demonstrate that interval kriging is more computationally efficient than 3D kriging because the covariance matrix is largely reduced without sacrificing borehole data. Moreover, interval kriging produces more realistic geologic characteristics than 2.5D kriging, while conditional to spatial borehole data. Compared to the multiple‐point statistics (MPS) algorithm—SNESIM, interval kriging can reproduce the geological architecture and spatial connectivity of channel‐type features, meanwhile producing tabular‐type features with better connectivity. Because the regularization term constrains kriged value toward 0 or 1, interval kriging produces more certainty in sand/non‐sand classification than 2.5D kriging, 3D kriging, and SNESIM. In conclusion, interval kriging is an effective and efficient 3D geostatistical algorithm that can capture the 3D structural complexity while significantly reducing computational time.
Plain Language Summary
Three‐dimensional (3D) computer models of sand and clay layers, using borehole data, help understand geology to support groundwater studies. This study introduces a new statistical method, interval kriging, to efficiently create 3D models of rock types based on borehole data. Interval kriging uses rock types and rock thickness information of boreholes to provide reasonable guesses on rock types and rock thicknesses at specified locations. Interval kriging can account for differences in directionality between horizontal and vertical dimensions. A new mathematical formula for the differences in directionality is developed. Also, a specialized computer code is developed to estimate rock types and rock thicknesses. The findings from four numerical and real‐world case studies show that interval kriging is faster than 3D kriging and produces more realistic geological features than 2.5D kriging. Additionally, interval kriging represents channel‐type of geological patterns and generates tabular‐type patterns presenting better connectivity than the multiple‐point statistics (MPS) algorithm, SNESIM. Furthermore, the probability fields generated by interval kriging provide more certainty compared to 2.5D kriging, 3D kriging, and the MPS algorithm. Interval kriging offers a significant advantage for studying complex geological structures because the method can efficiently reproduce realistic geological structures based on boreholes.
Key Points
An improved 3D kriging method is presented for irregular interval supports to efficiently perform complex lithofacies modeling
A new nested 3D irregular interval semivariogram is derived for modeling 3D anisotropies
A best linear unbiased estimator is from minimizing regularized estimation variance using a global‐local embedded genetic algorithm
In this study, the physiographic inundation model that comprehensively accounts for the physical process of overland flow due to heavy rainfall and typhoon‐induced storm surge was applied to describe ...potential inundation in a coastal zone. A comparative study was first conducted to validate the model; the simulated results excellently agree with the field measurement concerning inundated depth and area during Typhoons Haitang and Kalmaegi. The model was then applied to calculate the corresponding potential inundation, inundated area, and inundated risk in a flood‐prone coastal zone under design rainfall of seven return periods (2‐year, 5‐year, 10‐year, 20‐year, 50‐year, 100‐year, and 200‐year) and the given hydrograph of storm surge. The simulated result indicates that 7.59% of the study area is under flooding when the return period is 2‐year and the ratio increases to 10.16% when the return period is 200‐year. Moreover, the ratio of the inundated area where the inundated depth is greater than 1 m to the total inundated area increases with an increase in the return period. It can be also found that more severe inundation arises in the lagoon and estuary together with both sides of tidal reach of rivers which also have higher inundated depth and risk.
Although the theory of syndemics is principally a theory about population health, the past two decades' worth of quantitative literature motivated by the theory has generally focused on studying ...individuals rather than populations--and consequently has had very little to say about population health. Our aim in this Viewpoint is to critically review the literature on syndemics and to introduce key concepts for measuring their effects on population health.
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