28 research outputs found

    Loss of Asxl1 Alters Self-Renewal and Cell Fate of Bone Marrow Stromal Cell, Leading to Bohring-Opitz-like Syndrome in Mice

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    De novo ASXL1 mutations are found in patients with Bohring-Opitz syndrome, a disease with severe developmental defects and early childhood mortality. The underlying pathologic mechanisms remain largely unknown. Using Asxl1-targeted murine models, we found that Asxl1 global loss as well as conditional deletion in osteoblasts and their progenitors led to significant bone loss and a markedly decreased number of bone marrow stromal cells (BMSCs) compared with wild-type littermates. Asxl1(-/-) BMSCs displayed impaired self-renewal and skewed differentiation, away from osteoblasts and favoring adipocytes. RNA-sequencing analysis revealed altered expression of genes involved in cell proliferation, skeletal development, and morphogenesis. Furthermore, gene set enrichment analysis showed decreased expression of stem cell self-renewal gene signature, suggesting a role of Asxl1 in regulating the stemness of BMSCs. Importantly, re-introduction of Asxl1 normalized NANOG and OCT4 expression and restored the self-renewal capacity of Asxl1(-/-) BMSCs. Our study unveils a pivotal role of ASXL1 in the maintenance of BMSC functions and skeletal development

    Towards Evaluating Pitch-Related Phonation Function in Speech Communication Using High-Density Surface Electromyography

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    Pitch, as a sensation of the sound frequency, is a crucial attribute toward constructing a natural voice for communication. Producing intelligible sounds with normal pitches depend on substantive interdependencies among facial and neck muscles. Clarifying the interrelations between the pitches and the corresponding muscular activities would be helpful for evaluating the pitch-related phonating functions, which would play a significant role both in training pronunciation and in assessing dysphonia. In this study, the speech signals and the high-density surface electromyography (HD sEMG) signals were synchronously acquired when phonating [a:], [i:], and [ә:] vowels with increasing pitches, respectively. The HD sEMG energy maps were constructed based on the root mean square values to visualize spatiotemporal characteristics of facial and neck muscle activities. Normalized median frequency (nMF) and root-mean square (nRMS) were correspondingly extracted from the speech and sEMG recordings to quantitatively investigate the correlations between sound frequencies and myoelectric characteristics. The results showed that the frame-wise energy maps built from sEMG recordings presented that the muscle contraction strength increased monotonously across pitch-rising, with left-right symmetrical distribution for the face/neck. Furthermore, the nRMS increased at a similar rate to the nMF when there were rising pitches, and the two parameters had a significant correlation across different vowel tasks [(a:) (0.88 ± 0.04), (i:) (0.89 ± 0.04), and (ә:) (0.87 ± 0.05)]. These findings suggested the possibility of utilizing muscle contraction patterns as a reference for evaluating pitch-related phonation functions. The proposed method could open a new window for developing a clinical approach for assessing the muscular functions of dysphonia

    Challenges and Thoughts on Risk Management and Control for the Group Construction of a Super-Long Tunnel by TBM

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    The total length of the second stage of the water supply project in the northern areas of the Xinjiang Uygur Autonomous Region is 540 km, of which the total length of the tunnels is 516 km. The total tunneling mileage is 569 km, which includes 49 slow-inclined shafts and vertical shafts. Among the tunnels constructed in the project, the Ka–Shuang tunnel, which is a single tunnel with a length of 283 km, is currently the longest water-conveyance tunnel in the world. The main tunnel of the Ka–Shuang tunnel is divided into 18 tunnel-boring machine (TBM) sections, and 34 drilling-and-blasting sections, with 91 tunnel faces. The construction of the Ka–Shuang tunnel has been regarded as an unprecedented challenge for project construction management, risk control, and safe and efficient construction; it has also presented higher requirements for the design, manufacture, operation, and maintenance of the TBMs and their supporting equipment. Based on the engineering characteristics and adverse geological conditions, it is necessary to analyze the major problems confronted by the construction and systematically locate disaster sources. In addition, the risk level should be reasonably ranked, responsibility should be clearly identified, and a hierarchical-control mechanism should be established. Several techniques are put forward in this paper to achieve the objectives mentioned above; these include advanced geological prospecting techniques, intelligent tunneling techniques combined with the sensing and fusion of information about rock parameters and mechanical parameters, monitoring and early-warning techniques, and modern information technologies. The application of these techniques offers scientific guidance for risk control and puts forward technical ideas about improving the efficiency of safe tunneling. These techniques and ideas have great significance for the development of modern tunneling technologies and research into major construction equipment. Keywords: Super-long tunnels, Group construction by TBM, Risk management and control, Technical measure

    Reliability-Based View Synthesis for Free Viewpoint Video

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    View synthesis is a crucial technique for free viewpoint video and multi-view video coding because of its capability to render an unlimited number of virtual viewpoints from adjacent captured texture images and corresponding depth maps. The accuracy of depth maps is very important to the rendering quality, since depth image–based rendering (DIBR) is the most widely used technology among synthesis algorithms. There are some issues due to the fact that stereo depth estimation is error-prone. In addition, filling occlusions is another challenge in producing desirable synthesized images. In this paper, we propose a reliability-based view synthesis framework. A depth refinement method is used to check the reliability of depth values and refine some of the unreliable pixels, and an adaptive background modeling algorithm is utilized to construct a background image aiming to fill the remaining empty regions after a proposed weighted blending process. Finally, the proposed approach is implemented and tested on test video sequences, and experimental results indicate objective and subjective improvements compared to previous view synthesis methods

    Hybrid Temporal Correlation Based on Gaussian Mixture Model Framework for View Synthesis

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    As 3D video is explored as a hot research topic in the last few decades, free-viewpoint TV (FTV) is no doubt a promising field for its better visual experience and incomparable interactivity. View synthesis is obviously a crucial technology for FTV; it enables to render images in unlimited numbers of virtual viewpoints with the information from limited numbers of reference view. In this paper, a novel hybrid synthesis framework is proposed and blending priority is explored. In contrast to the commonly used View Synthesis Reference Software (VSRS), the presented synthesis process is driven in consideration of the temporal correlation of image sequences. The temporal correlations will be exploited to produce fine synthesis results even near the foreground boundaries. As for the blending priority, this scheme proposed that one of the two reference views is selected to be the main reference view based on the distance between the reference views and virtual view, another view is chosen as the auxiliary viewpoint, just assist to fill the hole pixel with the help of background information. Significant improvement of the proposed approach over the state-of –the-art pixel-based virtual view synthesis method is presented, the results of the experiments show that subjective gains can be observed, and objective PSNR average gains range from 0.5 to 1.3 dB, while SSIM average gains range from 0.01 to 0.05

    Electrochemical Corrosive Behaviors of Fe-Based Amorphous/Nanocrystalline Coating on Stainless Steel Prepared by HVOF-Sprayed

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    In this study, FeCrMnWMoSi amorphous/nanocrystalline coating was prepared on stainless steel by high-velocity oxygen fuel (HVOF) spraying. In order to thoroughly evaluate this novel material, the corrosion behaviors and corrosive film characteristics of the amorphous/nanocrystalline coating in NaCl corrosive media were studied using electrochemical measurement technologies such as potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). It was found that the corrosion resistance of Fe-based amorphous/nanocrystalline coating could be attributed to the passive film formed, which consisted of Fe, Cr, Mo, and W oxides. pH has an important influence on the corrosion resistance of amorphous/nanocrystalline coating by changing the pitting corrosion mechanism. Under neutral and acidic conditions, the corrosion mechanism of Fe-based amorphous/nanocrystalline coating was mainly local pitting corrosion. However, under strong alkaline conditions, the amorphous/nanocrystalline coating not only had pitting corrosion, but also had the active dissolution of the passive film. Therefore, the anti-corrosion performance of Fe-based amorphous/nanocrystalline coating under alkaline conditions was not as good as neutral and acidic corrosive medium

    A new regional cotton growth model based on reference crop evapotranspiration for predicting growth processes

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    Abstract Meteorological conditions and irrigation amounts are key factors that affect crop growth processes. Typically, crop growth and development are modeled as a function of time or growing degree days (GDD). Although the most important component of GDD is temperature, it can vary significantly year to year while also gradually shifting due to climate changes. However, cotton is highly sensitive to various meteorological factors, and reference crop evapotranspiration (ET O ) integrates the primary meteorological factors responsible for global dryland extension and aridity changes. This paper constructs a cotton growth model using ET O , which improves the accuracy of crop growth simulation. Two cotton growth models based on the logistic model established using GDD or ET O as independent factors are evaluated in this paper. Additionally, this paper examines mathematical models that relate irrigation amount and irrigation water utilization efficiency (IWUE) to the maximum leaf area index (LAI max ) and cotton yield, revealing some key findings. First, the model using cumulative reference crop evapotranspiration (CET O ) as the independent variable is more accurate than the one using cumulative growing degree days. To better reflect the effects of meteorological conditions on cotton growth, this paper recommends using CET O as the independent variable to establish cotton growth models. Secondly, the maximum cotton yield is 7171.7 kg/ha when LAI max is 6.043 cm2/cm2, the corresponding required irrigation amount is 518.793 mm, and IWUE is 21.153 kg/(ha·mm). Future studies should consider multiple associated meteorological factors and use ET O crop growth models to simulate and predict crop growth and yield

    Correction of Channel Imbalance for MIMO SAR Using Stepped-Frequency Chirps

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    To simultaneously achieve two-dimensional high resolution and wide swath in synthetic aperture radar (SAR), azimuth MIMO structure combined with stepped-frequency chirp signals was developed via splitting the antenna into N subapertures. During transmitting each subaperture transmits a chirp pulse at a different carrier frequency, while during receiving every subaperture receives the N scattered pulses at the same time. Separating the N scattered pulses received by each subaperture and downlinking them to the ground yield N2 different signal paths. Due to the dedicated network in the SAR system, the channel imbalance is inevitable. To correct the channel imbalance, this paper presents an external calibration method, where the channel characteristics are estimated from the peak value of a strong point target for each channel. Simulation and real raw data experiments are performed to validate the proposed method

    Application of eco-compensation to control transboundary water pollution in water diversion projects: The case of the Heihe River transfer project in China

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    Controlling transboundary water pollution is particularly crucial for the sustainable development of diversion basins, while eco-compensation is an essential incentive for multistakeholder transboundary water pollution control. Considering the dynamics of the various actors' pollution control behavior in the Heihe River water transfer project and utilizing differential game theory, we construct a baseline strategy, a horizontal eco-compensation strategy, and an incentive coordination strategy under scenarios with and without authority incentives. The corresponding equilibrium solutions are then determined, and comparisons are made between the payoffs of the players in the six different structures, thus defining the optimal scenario for the different programs. In the case of the largest ecological water transfer project of the Heihe River in Northwest China, according to the research findings, (1) when eco-compensation is funded through a single source, incentive coordination scenarios can contribute effectively to water pollution control instituted by the main participants in water diversion projects; when multiple financing sources are available, horizontal ecological compensation scenarios are more compatible with the individual interests of local municipalities to improve the water quality environment. (2) Water-receiving cities voluntarily eco-compensate for water-supplying cities, and this incentive structure for eco-compensation facilitates a significant improvement in the effectiveness of water pollution control and therefore the harmonious promotion of sustainable economic and environmental development in eco-fragile areas. (3) Water transfer projects, for which the two participants are at widely.different levels of development and the environment is inherently fragile, can facilitate, via an eco-compensation mechanism that combines horizontal and vertical scenarios, sustainable development-oriented policies for eco-compensation systems in which the authority participates as a third-party game player. The research supports the establishment of policies for the governance of the transboundary water diversion project basins to address conflicts in water pollution management
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