Wnt/β-Catenin Signaling in Mesenchymal Progenitors Controls Osteoblast and Chondrocyte Differentiation during Vertebrate Skeletogenesis

SummaryChondrocytes and osteoblasts are two primary cell types in the skeletal system that are differentiated from common mesenchymal progenitors. It is believed that osteoblast differentiation is controlled by distinct mechanisms in intramembranous and endochondral ossification. We have found that ectopic canonical Wnt signaling leads to enhanced ossification and suppression of chondrocyte formation. Conversely, genetic inactivation of β-catenin, an essential component transducing the canonical Wnt signaling, causes ectopic formation of chondrocytes at the expense of osteoblast differentiation during both intramembranous and endochondral ossification. Moreover, inactivation of β-catenin in mesenchymal progenitor cells in vitro causes chondrocyte differentiation under conditions allowing only osteoblasts to form. Our results demonstrate that β-catenin is essential in determining whether mesenchymal progenitors will become osteoblasts or chondrocytes regardless of regional locations or ossification mechanisms. Controlling Wnt/β-catenin signaling is a common molecular mechanism underlying chondrocyte and osteoblast differentiation and specification of intramembranous and endochondral ossification

The Wnt/β-Catenin Pathway Interacts Differentially with PTHrP Signaling to Control Chondrocyte Hypertrophy and Final Maturation

Sequential proliferation, hypertrophy and maturation of chondrocytes are required for proper endochondral bone development and tightly regulated by cell signaling. The canonical Wnt signaling pathway acts through β-catenin to promote chondrocyte hypertrophy whereas PTHrP signaling inhibits it by holding chondrocytes in proliferating states. Here we show by genetic approaches that chondrocyte hypertrophy and final maturation are two distinct developmental processes that are differentially regulated by Wnt/β-catenin and PTHrP signaling. Wnt/β-catenin signaling regulates initiation of chondrocyte hypertrophy by inhibiting PTHrP signaling activity, but it does not regulate PTHrP expression. In addition, Wnt/β-catenin signaling regulates chondrocyte hypertrophy in a non-cell autonomous manner and Gdf5/Bmp signaling may be one of the downstream pathways. Furthermore, Wnt/β-catenin signaling also controls final maturation of hypertrophic chondrocytes, but such regulation is PTHrP signaling-independent

An easy iris center detection method for eye gaze tracking system

Iris center detection accuracy has great impact on eye gaze tracking system performance. This paper proposes an easy and efficient iris center detection method based on modeling the geometric relationship between the detected rough iris center and the two corners of the eye. The method fully considers four states of iris within the eye region, i.e. center, left, right, and upper. The proposed active edge detection algorithm is utilized to extract iris edge points for ellipse fitting. In addition, this paper also presents a predicted edge point algorithm to solve the decrease in ellipse fitting accuracy, when part of the iris becomes hidden from rolling into a nasal or temporal eye corner. The evaluated result of the method on our eye database shows the global average accuracy of 94.3%. Compared with existing methods, our method achieves the highest iris center detection accuracy. Additionally, in order to test the performance of the proposed method in gaze tracking, this paper presents the results of gaze estimation achieved by our eye gaze tracking system

Body Parts Features Based Pedestrian Detection for Active Pedestrian Protection System

A novel pedestrian detection system based on vision in urban traffic situations is presented to help the driver perceive the pedestrian ahead of vehicle. To enhance the accuracy and to decrease the time consumption of pedestrian detection in such complicated situations, the pedestrian is detected by dividing it into several parts according to their corresponding features in the image. The candidate pedestrian leg is segmented based on the gentle Adaboost algorithm by training the optimized histogram of gradient features. The candidate pedestrian head is located by matching the pedestrian head and shoulder model above the region of the candidate leg. Then the candidate leg, head and shoulder are combined by parts constraint and threshold adjustment to verify the existence of pedestrian. Experiments in real urban traffic circumstances were conducted finally. Results show that the proposed pedestrian detection method can achieve a pedestrian detection rate of 92.1% with less time consumption

GraphGrind: addressing load imbalance of graph partitioning

The incidence of HCAIs before and after antimicrobial stewardship. Incidence of VAP, CRBSI and CAUTI were defined as the number of VAP, CRBSI and CAUTI patients per 1000 ventilation days, per 1000 central venous catheter days and per 1000 urine-catheter days, respectively. (DOCX 15 kb

Service utilization in community health centers in China: a comparison analysis with local hospitals

BACKGROUND: Being an important part of China's Urban Health Care Reform System, Community Health Centers (CHCs) have been established throughout the entire country and are presently undergoing substantial reconstruction. However, the services being delivered by the CHCs are far from reaching their performance targets. In order to assess the role of the CHCs, we examined their performance in six cities located in regions of South-East China. The purpose of this investigation was to identify the utilization and the efficiency of community health resources that are able to provide basic medical and public health services. METHODS: The study was approved by Peking University Health Science Center Institutional Reviewing Board (NO: IRB00001052-T1). Data were collected from all the local health bureaux and processed using SPSS software. Methods of analysis mainly included: descriptive analysis, paired T-test and one-way ANOVA. RESULTS: The six main functions of the CHCs were not fully exploited and the surveys that were collected on their efficiency and utilization of resources indicate that they have a low level of performance and lack the trust of local communities. Furthermore, the CHCs seriously lack funding support and operate under difficult circumstances, and residents have less positive attitudes towards them. CONCLUSION: The community health service must be adjusted according to the requirements of urban medical and health reform, taking into account communities' health needs. More research is required on the living standards and health needs of residents living within the CHC's range, taking into consideration the users' needs in expanding the newly implemented service, and at the same time revising the old service system so as to make the development of CHCs realistic and capable of providing a better service to patients. Several suggestions are put forward for an attainable scheme for developing a community health service

Molecular Signatures of Humic Acids from Different Sources as Revealed by Ultrahigh Resolution Mass Spectrometry

Humic acid (HA) is extremely important for understanding the geochemical cycle of pollutants in different environments. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has performed molecular-level analysis of two standard HAs from the Suwannee River (SRHA) and leonardite (LEHA) and HA from Jiufeng forest in Beijing (JFHA), which is impossible for other conventional instruments. Regardless of the source of HA, compounds containing more heteroatoms (such as nitrogen and sulfur) have a higher degree of unsaturation and aromaticity. JFHA, SRHA, and LEHA from soil, river, and leonardite, respectively, are arranged in order from the lowest to highest degree of humification, according to molecular unsaturation and aromaticity of HAs. Soil HA is more labile and contains many large molecular weight compounds with low unsaturation. Regardless of unsaturation, molecules of River HA have a homogeneous molecular mass distribution and contain many plant-derived lignin- and tannin-like compounds, which are more stable than lipid and more labile than condensed aromatics. Leonardite HA with a high degree of humification contains a large number of compounds with high aromaticity and more heteroatoms and has low lability. Our results reveal the diversity of humic acid at molecular level because of different degree of humification and the lability. These conclusions are significant for understanding the role of humic acid from different sources in pollutant transformation and the geochemical cycle at the molecular level

Novel Registration and Fusion Algorithm for Multimodal Railway Images with Different Field of Views

Objects intruding high-speed railway clearance do great threat to running trains. In order to improve accuracy of railway intrusion detection, an automatic multimodal registration and fusion algorithm for infrared and visible images with different field of views is presented. The ratio of the nearest to next nearest distance, geometric, similar triangle, and RANSAC constraints are used to refine the matching SURF feature points successively. Correct matching points are accumulated with multiframe to overcome the insufficient matching points in single image pair. After being registered, an improved Contourlet transform fusion algorithm combined with total variation and local region energy is proposed. Inverse Contourlet transform to low frequency subband coefficient fused with total variation model and high frequency subband coefficients fused with local region energy is used to reconstruct the fused image. The comparison to other 4 popular fusion methods shows that our algorithm has the best comprehensive performance for multimodal railway image fusion

Study on Cynodon dactylon root system affecting dry–wet cracking behavior and shear strength characteristics of expansive soil

Abstract Expansive soil exhibits remarkable characteristics of water absorption expansion and water loss shrinkage, rendering it susceptible to cracking under the alternating dry–wet environments of nature. The generation and development of cracks in expansive soil can result in catastrophic engineering accidents such as landslides. Vegetation protection is an important approach to stabilizing expansive soil slopes and fulfilling ecological protection requirements. In this study, through indoor experiments and theoretical analysis methods, the effects of Cynodon dactylon roots on the crack development and shear strength of expansive soil subjected to dry–wet cycles were analyzed, and the relationship between the crack development and shear strength decay in root-doped expansive soil was explored. Furthermore, the mechanism of vegetative root system action was elucidated. The results show that the Cynodon dactylon root system exerts a significant inhibitory effect on crack development in expansive soil. The crack indexes of root-doped expansive soil exhibit significant phase characteristics during the process of dry–wet cycles. The crack-blocking and reinforcing effect of the root system becomes pronounced as the root-to-soil mass ratio increases and the root diameter decreased. Moreover, the process of crack development in expansive soil is accompanied by a decrease in soil shear strength. The quantitative relationship between crack development and shear strength decay can serve as a basis for predicting the stability of slope soil. Overall, the results highlight the potential of vegetation-based approaches in protecting slopes with expansive soils and have practical implications for ecological protection and engineering design in areas with expansive soils