The thickness of a slim disk is determined by the balance between the radiation force and the vertical component of the gravity of the black hole (BH). Vertical gravity is found to increase with the ...disk height, and it will decrease with the disk height if the disk thickness is above a critical value, which implies that gas at the disk surface may be driven into outflows by radiation force when the disk thickness surpasses the critical value. In this work, we derive a global solution to a slim disk with radiation-driven outflows. We find that the outflows are driven from the disk surface if the mass accretion rate is m ˙ 1.78 − 1.91 ( m ˙ = M ˙ M ˙ Edd and M ˙ Edd = L Edd 0.1 c 2 ) depending on the BH mass, while the outflows are suppressed when the mass accretion rate is lower than this critical value. The mass accretion rate decreases with the decreasing radius in the disk with outflows, and the rate of the gas swallowed by the BH is always limited to m ˙ in ∼ 1.78 − 1.91 even if the mass accretion rate at the outer edge of the disk is very high. This may set constraints on the massive BH growth through accretion in the early universe. Due to the presence of outflows, there is an upper limit on the radiation flux of the disk, which leads to saturation of the continuum spectra of the disk with outflows at the high-energy band. This may be tested by the observations of quasars or/and BH X-ray binaries.
Stressors can have negative effects on well‐being, but little is known about how an individual's inability to precisely forecast upcoming stress could be a risk factor for well‐being. Antecedents and ...outcomes of two stress forecasting variables, anticipated stress level and underestimation errors in stress forecasting (operationalized by the residual change scores obtained by regressing the evening experienced stress on the morning anticipated stress), were investigated. In a daily diary study of 110 undergraduate students over a workweek, poor sleep quality and negative affect reported in the morning predicted a higher anticipated stress of the upcoming day. Poor sleep quality was found to be related to less underestimation errors (i.e., more overestimation). Mispredicting the daily stress level was found to predict greater health complaints and negative affect by the end of the day. Those high on trait resilience were found to make fewer underestimation errors on average. Worse emotional outcomes were associated with underestimation errors during stress forecasting than with overestimation errors. This study demonstrates that examining an individual's experience in forecasting upcoming stressors is an important area for future research in determining points of intervention to promote adaptive management of daily demands.
While domain adaptation (DA) aims to associate the learning tasks across data domains, heterogeneous domain adaptation (HDA) particularly deals with learning from cross-domain data which are of ...different types of features. In other words, for HDA, data from source and target domains are observed in separate feature spaces and thus exhibit distinct distributions. In this paper, we propose a novel learning algorithm of Cross-Domain Landmark Selection (CDLS) for solving the above task. With the goal of deriving a domain-invariant feature subspace for HDA, our CDLS is able to identify representative cross-domain data, including the unlabeled ones in the target domain, for performing adaptation. In addition, the adaptation capabilities of such cross-domain landmarks can be determined accordingly. This is the reason why our CDLS is able to achieve promising HDA performance when comparing to state-of-the-art HDA methods. We conduct classification experiments using data across different features, domains, and modalities. The effectiveness of our proposed method can be successfully verified.
A growing body of evidence suggests that microbial α-diversity (local species richness) may have positive effects on ecosystem function. However, less attention has been paid to β-diversity (the ...variation among local microbial assemblages). Here we studied the impact of microbial α-diversity on stochastic/deterministic microbial community assembly processes, which are related to β-diversity, and the consequences for community function. Bacterial communities differing in α-diversity were generated and their structures and potential community functional traits were inferred from DNA sequencing. Phylogenetic null modeling analysis suggests that stochastic assembly processes are dominant in high-diversity communities. However, in low-diversity communities, deterministic assembly processes are dominant, associating with the reduction of specialized functions that are correlated with specific bacterial taxa. Overall, we suggest that the low-diversity-induced deterministic community assembly processes may constrain community functions, highlighting the potential roles of specialized functions in community assembly and in generating and sustaining the function of soil ecosystems.
•Thermal buckling analysis of FGM beams by various theories are presented.•A two-step perturbation method is employed to determine the critical buckling loads and post-buckling equilibrium paths.•The ...post-buckling equilibrium path for FGM beam with two clamped ends is also of the bifurcation type for any various displacement fields.
In the present work, attention is focused on the prediction of thermal buckling and post-buckling behaviors of functionally graded materials (FGM) beams based on Euler–Bernoulli, Timoshenko and various higher-order shear deformation beam theories. Two ends of the beam are assumed to be clamped and in-plane boundary conditions are immovable. The beam is subjected to uniform temperature rise and temperature dependency of the constituents is also taken into account. The governing equations are developed relative to neutral plane and mid-plane of the beam. A two-step perturbation method is employed to determine the critical buckling loads and post-buckling equilibrium paths. New results of thermal buckling and post-buckling analysis of the beams are presented and discussed in details, the numerical analysis shows that, for the case of uniform temperature rise loading, the post-buckling equilibrium path for FGM beam with two clamped ends is also of the bifurcation type for any arbitrary value of the power law index and any various displacement fields.
The Cucurbita genus contains several economically important species in the Cucurbitaceae family. Here, we report high-quality genome sequences of C. maxima and C. moschata and provide evidence ...supporting an allotetraploidization event in Cucurbita. We are able to partition the genome into two homoeologous subgenomes based on different genetic distances to melon, cucumber, and watermelon in the Benincaseae tribe. We estimate that the two diploid progenitors successively diverged from Benincaseae around 31 and 26 million years ago （Mya）, respectively, and the allotetraploidization happened at some point between 26 Mya and 3 Mya, the estimated date when C. maxima and C. moschata diverged. The subgenomes have largely maintained the chromosome structures of their diploid progenitors. Such long-term karyotype stability after polyploidization has not been commonly observed in plant polyploids. The two subgenomes have retained similar numbers of genes, and neither subgenome is globally dominant in gene expression. Allele-specific expression analysis in the C. maxima ×C. moschata interspecific F1 hybrid and their two parents indicates the predominance of trans-regulatory effects underlying expression divergence of the parents, and detects transgressive gene expression changes in the hybrid correlated with heterosis in important agronomic traits. Our study provides insights into polyploid genome evolution and valuable resources for genetic improvement of cucurbit crops.
This paper studies how to efficiently apply device-to-device (D2D) communications underlaying a cellular system to support vehicle-to-vehicle (V2V) connection (termed D2D-V). By considering the ...geographic features of the D2D-V system, we propose a D2D-V grouping, reuse channel selection (RS), and power control (PC) framework to achieve the optimal performance of the D2D-V system, in terms of either maximized sum rate or maximized minimally achievable rate. First, in a full channel state information (CSI) scenario, we apply difference of two convex functions (D.C.) programming to obtain the optimal PC. However, because the CSI between some terminals is hard to obtain and some interference can be appropriately inhibited by taking advantage of the vehicles' geographic features, we make a series of simplifications to the PC problem to reduce the requirement of full CSI, the dependence of centralized control, and the computational complexity. The suitable conditions of each simplification are elaborated. Each step of our simplifications are shown as a certain tradeoff between performance and complexity. Furthermore, we provide an investigation into the service quality that one vehicle can achieve when it passes through the covered segment of the highway and propose the location-service curve to portray this. We use numerical simulations to verify the accuracy and feasibility of each step of our suboptimal PC and specific features embedded in the location-service curve.
Abstract The color index ( J − K ) 0 of tip-red-giant branch (TRGB) is used to study the metallicity distribution in the Large and Small Magellanic Cloud. With the most complete and pure sample of ...red member stars so far, the areas are divided into 154 and 70 bins for the LMC and SMC, respectively, with similar number of stars by the Voronoi binning. For each bin, the position of TRGB on the near-infrared color–magnitude diagram, specifically ( J − K ) 0 / K 0 , is determined by the poison-noise weighted method. Converting the color index of TRGB into metallicity, the metallicity gradients in the LMC and the SMC are obtained in four major directions. For the LMC, the gradient to the north is −0.006 ± 0.004 dex kpc −1 , to the south −0.010 ± 0.005 dex kpc −1 , to the east −0.006 ± 0.003 dex kpc −1 , and to the west −0.010 ± 0.003 dex kpc −1 . The farthest distance extends to 16 kpc. For the SMC, the gradients to the north, south, east, and west are −0.017 ± 0.031 dex kpc −1 , −0.016 ± 0.007 dex kpc −1 , −0.003 ± 0.002 dex kpc −1 , and −0.004 ± 0.003 dex kpc −1 , respectively. The farthest distance for the SMC extends to 27 kpc. The gradient is large from the center to 1 kpc.
On wave propagation of porous nanotubes She, Gui-Lin; Yuan, Fuh-Gwo; Ren, Yi-Ru
International journal of engineering science,
September 2018, 2018-09-00, Letnik:
130
Journal Article
Recenzirano
An analytic model of porous nanotubes for the wave propagation analysis is formulated with the help of the nonlocal strain gradient theory. The dispersion relations between phase velocity and wave ...number is determined by solving an eigenvalue problem. It is found that the asymptotic phase velocity can be increased by increasing the strain gradient parameter or decreasing the nonlocal parameter. In addition, the heterogeneity of functionally graded materials and temperature variation have a substantial influence on the dispersion relations of nanotubes. The nonlocal parameter and strain gradient parameter have significant effects on the dispersion relation at high wave numbers, in contrast, this effects can be negligible at low wave numbers. Meanwhile, it can be inferred that the phase velocity can decrease or increase as the porosity volume fraction rises, which depends on the power law index.
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