Exploratory chandra observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30

We report exploratory Chandra observations of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30. The quasar is clearly detected by Chandra with a possible component of extended emission.Y.-L.A. thanks the support from NSFC grant Nos. 11273060, 11333008, and State Key Development Program for Basic Research of China (Nos. 2013CB834900 and 2015CB857000). F.W. and X.-B.W. thank the support from the NSFC grants No.11373008 and 11533001, the Strategic Priority Research Program “The Emergence of Cosmological Structures” of the Chinese Academy of Sciences, grant No. XDB09000000, and the National Key Basic Research Program of China 2014CB845700

Conservation and diversification of the miR166 family in soybean and potential roles of newly identified miR166s

Identity between pre-miR166s in soybean. (TIF 5906 kb

A SURVEY OF LUMINOUS HIGH-REDSHIFT QUASARS WITH SDSS AND WISE. II. THE BRIGHT END OF THE QUASAR LUMINOSITY FUNCTION AT z similar to 5

This is the second paper in a series on a new luminous z ~ 5 quasar survey using optical and near-infrared colors. Here we present a new determination of the bright end of the quasar luminosity function (QLF) at z ~ 5. Combining our 45 new quasars with previously known quasars that satisfy our selections, we construct the largest uniform luminous z ~ 5 quasar sample to date, with 99 quasars in the range of 4.7 ≤ z < 5.4 and −29 < M 1450 ≤ −26.8, within the Sloan Digital Sky Survey (SDSS) footprint. We use a modified 1/V a method including flux limit correction to derive a binned QLF, and we model the parametric QLF using maximum likelihood estimation. With the faint-end slope of the QLF fixed as α = −2.03 from previous deeper samples, the best fit of our QLF gives a flatter bright end slope β = −3.58 ± 0.24 and a fainter break magnitude ${M}_{1450}^{* }$ = −26.98 ± 0.23 than previous studies at similar redshift. Combined with previous work at lower and higher redshifts, our result is consistent with a luminosity evolution and density evolution model. Using the best-fit QLF, the contribution of quasars to the ionizing background at z ~ 5 is found to be 18%–45% with a clumping factor C of 2–5. Our sample suggests an evolution of radio loud fraction with optical luminosity but no obvious evolution with redshift

Revealing the Accretion Physics of Supermassive Black Holes at Redshift z~7 with Chandra and Infrared Observations

X-ray emission from quasars has been detected up to redshift $z=7.5$, although only limited to a few objects at $z>6.5$. In this work, we present new Chandra observations of five $z>6.5$ quasars. By combining with archival Chandra observations of six additional $z>6.5$ quasars, we perform a systematic analysis on the X-ray properties of these earliest accreting supermassive black holes (SMBHs). We measure the black hole masses, bolometric luminosities ($L_{\rm bol}$), Eddington ratios ($\lambda_{\rm Edd}$), emission line properties, and infrared luminosities ($L_{\rm IR}$) of these quasars using infrared and sub-millimeter observations. Correlation analysis indicates that the X-ray bolometric correction (the factor that converts from X-ray luminosity to bolometric luminosity) decreases with increasing $L_{\rm bol}$, and that the UV/optical-to-X-ray ratio, $\alpha_{\rm ox}$, strongly correlates with $L_{\rm 2500}$, and moderately correlates with $\lambda_{\rm Edd}$ and blueshift of CIV emission lines. These correlations are consistent with those found in lower-$z$ quasars, indicating quasar accretion physics does not evolve with redshift. We also find that $L_{\rm IR}$ does not correlate with $L_{\rm 2-10 keV}$ in these luminous distant quasars, suggesting that the ratio of the SMBH growth rate and their host galaxy growth rate in these early luminous quasars are different from those of local galaxies. A joint spectral analysis of the X-ray detected $z>6.5$ quasars yields an average X-ray photon index of $\Gamma=2.32^{+0.31}_{-0.30}$, steeper than that of low-$z$ quasars. By comparing it with the $\Gamma-\lambda_{\rm Edd}$ relation, we conclude that the steepening of $\Gamma$ for quasars at $z>6.5$ is mainly driven by their higher Eddington ratios.Comment: 16 pages, 10 figures, Accepted for publication in Ap

Вирусная реклама как средство привлечения внимания к услугам организации

ВКР посвящена изучению вирусной рекламы как средства привлечения внимания к услугам организации. Автором был разработан комплекс необходимых рекламных продуктов и мероприятий для привлечения внимания к услугам магазина детских товаров нового сегмента целевой аудитории

Evaluation of individual and ensemble probabilistic forecasts of COVID-19 mortality in the United States

Short-term probabilistic forecasts of the trajectory of the COVID-19 pandemic in the United States have served as a visible and important communication channel between the scientific modeling community and both the general public and decision-makers. Forecasting models provide specific, quantitative, and evaluable predictions that inform short-term decisions such as healthcare staffing needs, school closures, and allocation of medical supplies. Starting in April 2020, the US COVID-19 Forecast Hub (https://covid19forecasthub.org/) collected, disseminated, and synthesized tens of millions of specific predictions from more than 90 different academic, industry, and independent research groups. A multimodel ensemble forecast that combined predictions from dozens of groups every week provided the most consistently accurate probabilistic forecasts of incident deaths due to COVID-19 at the state and national level from April 2020 through October 2021. The performance of 27 individual models that submitted complete forecasts of COVID-19 deaths consistently throughout this year showed high variability in forecast skill across time, geospatial units, and forecast horizons. Two-thirds of the models evaluated showed better accuracy than a naïve baseline model. Forecast accuracy degraded as models made predictions further into the future, with probabilistic error at a 20-wk horizon three to five times larger than when predicting at a 1-wk horizon. This project underscores the role that collaboration and active coordination between governmental public-health agencies, academic modeling teams, and industry partners can play in developing modern modeling capabilities to support local, state, and federal response to outbreaks

The United States COVID-19 Forecast Hub dataset

Academic researchers, government agencies, industry groups, and individuals have produced forecasts at an unprecedented scale during the COVID-19 pandemic. To leverage these forecasts, the United States Centers for Disease Control and Prevention (CDC) partnered with an academic research lab at the University of Massachusetts Amherst to create the US COVID-19 Forecast Hub. Launched in April 2020, the Forecast Hub is a dataset with point and probabilistic forecasts of incident cases, incident hospitalizations, incident deaths, and cumulative deaths due to COVID-19 at county, state, and national, levels in the United States. Included forecasts represent a variety of modeling approaches, data sources, and assumptions regarding the spread of COVID-19. The goal of this dataset is to establish a standardized and comparable set of short-term forecasts from modeling teams. These data can be used to develop ensemble models, communicate forecasts to the public, create visualizations, compare models, and inform policies regarding COVID-19 mitigation. These open-source data are available via download from GitHub, through an online API, and through R packages

Bitter gourd has the highest azoxystrobinon residue after open field application on four cucurbit vegetables.

The goal of this study was to select a representative cucurbit vegetable crop that contained the highest residue levels of the pesticide azoxystrobinon. To do this, we used open field application of azoxystrobinon in four cucurbit crops (cucumber, zucchini, bitter gourd, and loofah) in Beijing, Shandong, and Anhui. Liquid chromatograph-mass spectrometry/mass spectrometry (LC-MS/MS) with selected reaction monitoring was used to determine azoxystrobinon levels in each of the selected cucurbit vegetables. The azoxystrobinon limit of detection was 0.005 mg kg-1 for all samples. Recoveries of azoxystrobinon ranged from 94.2% to 107.1% at spiked levels of 0.005-0.5 mg kg-1. In field trials, the half-life of azoxystrobinon in each of the four cucurbit crops was within the range of 1.4-3.1 d. Based on these results, we recommend that bitter gourd is selected as a representative cucurbit vegetable for future studies of azoxystrobinon. The obtained residual data were also assessed for their dietary risk and results indicated that there is no chronic dietary risk in any of the four, selected cucurbit vegetables. The recommended maximum residue limit (MRL) of azoxystrobinon in this subgroup was 0.2 mg/kg

EXPLORATORY CHANDRA OBSERVATION OF THE ULTRALUMINOUS QUASAR SDSS J010013.02+280225.8 at REDSHIFT 6.30

We report exploratory Chandra observations of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30. The quasar is clearly detected by Chandra with a possible component of extended emission. The rest-frame 2–10 keV luminosity is - ´ + 9.0 4.5 9.1 1045 erg s−1 with an inferred photon index of Γ = - + 3.03 0.70 0.78. This quasar is X-ray bright, with an inferred X-ray-to-optical flux ratio aox = - - + 1.22 0.05 0.07, higher than the values found in other quasars of comparable ultraviolet luminosity. The properties inferred from this exploratory observation indicate that this ultraluminous quasar might be growing with super-Eddington accretion and probably viewed with a small inclination angle. Deep X-ray observations will help to probe the plausible extended emission and better constrain the spectral features for this ultraluminous quasar