325 research outputs found
Factors Affecting Consultation Volume in an Online Healthcare Community: Evidence from Online Data in China
Under the background of sharing economy, online healthcare has been developing rapidly to ease the pressure of offline medical care. The interaction between doctors and patients is the key element of the sustainable development of online healthcare communities. To explore the influence of doctors\u27 online word-of-mouth, online vitality and consulting service price on consultation volume, we build a multiple regression model taking consultation volume as the dependent variable, online word-of-mouth and online vitality and consulting service price as independent variables. By analyzing the data of 37,977 doctors collected from the online healthcare community, we find that doctors\u27 online word-of-mouth and online vitality have significant positive impacts on consultation volume. Our results also show that there is an inverted U-shaped relationship between consulting service price and consultation volume, and online word-of-mouth has a greater impact on consultation volume than any other factors. Finally, we put forward suggestions for doctors in online healthcare communities
Study on the technology and properties of 3D bioprinting SF/GT/n-HA composite scaffolds
In this paper, three kinds of natural polymer materials, silk fibroin (SF), gelatin (GT), and nano-hydroxyapatite (n-HA), are mixed as 3D printing bioink to mimic protein polysaccharide and collagen fibers in natural articular cartilage. By changing the SF content, SF/GT/n-HA composite scaffolds with different ratios are prepared using 3D bioprinting technology. The microstructure and morphology, biological properties and mechanical properties of composite scaffolds are characterized. The results show that the printing precision of the bioink with 10% SF is best, and the composite scaffold with 10% SF also exhibits better mechanical properties, whose tensile elastic modulus is 10.60 ± 0.32 MPa and the compression elastic modulus is 1.22 ± 0.06 MPa. These studies are helpful to understand the interaction between SF, GT and n-HA, and provide a theoretical basis for the preparation of better silk fibroin-based composite scaffolds
Artemisinin derivative SM934, influences the activation, proliferation, differentiation and antibody-secreting capacity of β-cells in systemic lupus erythematosus mice via inhibition of TLR7/9 signaling pathway
Purpose: To study the influence of artemisinin derivative, SM934 on activation, proliferation, differentiation and antibody-secreting capacity of B cells of systemic lupus erythematosus (SLE) mice, and the underlying mechanism.
Methods: Female MRL/lpr mice (n = 60) were randomly assigned to four groups of 15 mice each: SLE, 2.5 mg/kg SM934; 5 mg/kg SM934, and 10 mg/kg SM934 groups. Serum levels of interleukins 6, 10, 17 and 21 (IL-6, IL-17, IL-10 and IL-21) were determined. The secretions of immunoglobulins G and M (IgG and IgM) by B cells were determined. The population of B lymphocyte subtypes was determined flow cytometrically. The expressions of Blimp-1 and Bcl-6, Toll-like receptors 7 and 9 (TLR7 and TLR9) mRNAs were determined.
Results: SLE-induced upregulation of serum IL-10, IL-6, IL-17 and IL-21 was significantly and dosedependently reduced following a 2-month treatment with SM934 (p < 0.01). Treatment with SM934 significantly and dose-dependently accentuated B cell germinal center B cell populations, but significantly and dose-dependently decreased the populations of plasma and activated B cells (p < 0.01). The splenic levels of IgG and IgM were decreased in a dose-dependent fashion after 8 weeks of treatment (p < 0.01). Artemisinin derivative SM934 decreased the expression of Blimp-1, and upregulated the expression of Bcl-6, both in a dose-dependent manner (p < 0.01). Moreover, SM934 decreased the mRNA expressions of TLR7 and TLR9 in a dose-based manner (p < 0.01).
Conclusion: Artemisinin derivative SM934 mitigates LSE syndromes by suppressing the TLR-induced B-cell stimulation and plasma cell generatio
The Hotspots of Social Commerce:A Literate View
Social commerce is a new economic and business model that has been rapidly risen and developed in recent years, which has aroused widespread concern in both the business and academic community. In this paper, we adopt the information visualization technology to econometrically analyze the co-citation data of the social commerce fields retrieved by Web of Science from 2005 to 2017, then explore the time and space distribution of the social commerce, and analyze the cooperation network of institutions and periodicals for the published papers in this field. At the end of the paper, we present the frontier and hot topics of social commerce based on the analysis of high-frequency keywords, co-occurrence, and the rate of burst term. We hope that it will provide constructive reference and guidance for the following related studies in the area of social commerce
The Viscosity Characteristics for the Mixed Refrigerant HFO-1234yf + HFC-152a
Refrigerants are improved with the development of refrigeration and air conditioning industry. Because of the long-term use of chlorine-containing halogenated hydrocarbon substances, the ozone depletion and global warming become important issues around the world. Searching for refrigerants with low GWP (Global Warming Potential) and zero ODP (Ozone Depletion Potential) is urgent. HFC-134a used to be a widely used refrigerant with zero ODP. However, its high GWP of 1300 and long atmospheric lifetime of 14 years would cause the problem of global warming. Thus, for the sake of environment, the substitution of HFC-134a is imperative. In recent years, HFO-1234yf has been regarded as one of the widely used substitutions of HFC-134a because of low GWP of 4 and similar thermophysical properties to HFC-134a. However, its COP is slightly smaller than that of HFC-134a. In order to make better use of HFO-1234yf, some HFO-1234yf + HFCs or HFO-1234yf + HCs binary mixtures were proposed as alternative refrigerants. HFC-152a with low GWP of 140 and a short atmospheric lifetime of 1.5 years was selected as component in refrigerant mixtures. The mixture HFO-1234yf + HFC-152a is a promising alternative refrigerant. Before the actual application of alternative refrigerants in the refrigeration and air conditioning systems, thermophysical properties of mixed refrigerants need to be carefully investigated. Knowledge of viscosity characteristics, as one of the major concerns in the study of the thermophysical properties of alternative refrigerants, has significant impact on heat transfer and pressure drop in the flow, and viscosity data with high accuracy are of considerable value in the calculation of heat transfer and fluid flow. Â Â Â Â Â Â Thus, in this work, the measurement of liquid viscosity of the mixture was carried out with a new type of gravitational capillary viscometer developed in our previous work. The liquid viscosity experimental system used in this paper consists of a gravitational capillary viscometer made of glass, a pressure vessel with sight glasses, a thermostatic bath system and a measurement system. The measurement system consists of a high accurate temperature measure system (the standard temperature uncertainty is less than 0.011K) and a high accurate pressure measure system (the standard pressure uncertainty is within 1.4 kPa). The expanded uncertainty of dynamic viscosity was 1.58 %. The reliability of the experimental apparatus has been validated with HFO-1234yf and the binary mixture HFC-22 + HFC-134a (0.7 + 0.3, by mole fraction) in previous work. Based on this, the gravitational capillary viscometer was firstly calibrated with HCFC-22, and then, the liquid viscosity data of the binary mixture HFO-1234yf + HFC-152a (0.81 + 0.19, by mole fraction) were given from 278.15 K to 333.15 K. Two most commonly used viscosity models based on the Andrade equation were used to correlate the experimental data of the mixture HFO-1234yf + HFC-152a (0.81 + 0.19, by mole fraction). The correlation results were discussed
Spatial Self-Distillation for Object Detection with Inaccurate Bounding Boxes
Object detection via inaccurate bounding boxes supervision has boosted a
broad interest due to the expensive high-quality annotation data or the
occasional inevitability of low annotation quality (\eg tiny objects). The
previous works usually utilize multiple instance learning (MIL), which highly
depends on category information, to select and refine a low-quality box. Those
methods suffer from object drift, group prediction and part domination problems
without exploring spatial information. In this paper, we heuristically propose
a \textbf{Spatial Self-Distillation based Object Detector (SSD-Det)} to mine
spatial information to refine the inaccurate box in a self-distillation
fashion. SSD-Det utilizes a Spatial Position Self-Distillation \textbf{(SPSD)}
module to exploit spatial information and an interactive structure to combine
spatial information and category information, thus constructing a high-quality
proposal bag. To further improve the selection procedure, a Spatial Identity
Self-Distillation \textbf{(SISD)} module is introduced in SSD-Det to obtain
spatial confidence to help select the best proposals. Experiments on MS-COCO
and VOC datasets with noisy box annotation verify our method's effectiveness
and achieve state-of-the-art performance. The code is available at
https://github.com/ucas-vg/PointTinyBenchmark/tree/SSD-Det.Comment: accepted by ICCV 202
Two Rapid Power Iterative DOA Estimators for UAV Emitter Using Massive/Ultra-massive Receive Array
To provide rapid direction finding (DF) for unmanned aerial vehicle (UAV)
emitter in future wireless networks, a low-complexity direction of arrival
(DOA) estimation architecture for massive multiple input multiple output (MIMO)
receiver arrays is constructed. In this paper, we propose two strategies to
address the extremely high complexity caused by eigenvalue decomposition of the
received signal covariance matrix. Firstly, a rapid power-iterative rotational
invariance (RPI-RI) method is proposed, which adopts the signal subspace
generated by power iteration to gets the final direction estimation through
rotational invariance between subarrays. RPI-RI makes a significant complexity
reduction at the cost of a substantial performance loss. In order to further
reduce the complexity and provide a good directional measurement result, a
rapid power-iterative Polynomial rooting (RPI-PR) method is proposed, which
utilizes the noise subspace combined with polynomial solution method to get the
optimal direction estimation. In addition, the influence of initial vector
selection on convergence in the power iteration is analyzed, especially when
the initial vector is orthogonal to the incident wave. Simulation results show
that the two proposed methods outperform the conventional DOA estimation
methods in terms of computational complexity. In particular, the RPIPR method
achieves more than two orders of magnitude lower complexity than conventional
methods and achieves performance close to CRLB. Moreover, it is verified that
the initial vector and the relative error have a significant impact on the
performance of the computational complexity
High-performance Power Allocation Strategies for Active IRS-aided Wireless Network
Due to its intrinsic ability to combat the double fading effect, the active
intelligent reflective surface (IRS) becomes popular. The main feature of
active IRS must be supplied by power, and the problem of how to allocate the
total power between base station (BS) and IRS to fully explore the rate gain
achieved by power allocation (PA) to remove the rate gap between existing PA
strategies and optimal exhaustive search (ES) arises naturally. First, the
signal-to-noise ratio (SNR) expression is derived to be a function of PA factor
beta [0, 1]. Then, to improve the rate performance of the conventional gradient
ascent (GA), an equal-spacing-multiple-point-initialization GA (ESMPI-GA)
method is proposed. Due to its slow linear convergence from iterative GA, the
proposed ESMPI-GA is high-complexity. Eventually, to reduce this high
complexity, a low-complexity closed-form PA method with third-order Taylor
expansion (TTE) centered at point beta0 = 0.5 is proposed. Simulation results
show that the proposed ESMPI-GA and TTE obviously outperform existing methods
like equal PA
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