Bit Allocation using Optimization

In this paper, we consider the problem of bit allocation in neural video compression (NVC). Due to the frame reference structure, current NVC methods using the same R-D (Rate-Distortion) trade-off parameter $\lambda$ for all frames are suboptimal, which brings the need for bit allocation. Unlike previous methods based on heuristic and empirical R-D models, we propose to solve this problem by gradient-based optimization. Specifically, we first propose a continuous bit implementation method based on Semi-Amortized Variational Inference (SAVI). Then, we propose a pixel-level implicit bit allocation method using iterative optimization by changing the SAVI target. Moreover, we derive the precise R-D model based on the differentiable trait of NVC. And we show the optimality of our method by proofing its equivalence to the bit allocation with precise R-D model. Experimental results show that our approach significantly improves NVC methods and outperforms existing bit allocation methods. Our approach is plug-and-play for all differentiable NVC methods, and it can be directly adopted on existing pre-trained models

Current Research Problems of Chronic Arsenicosis in China

Chronic arsenicosis is a newly-emerged public-health issue in China and many other Asian countries. Over 200 million people are estimated to be at the risk of high arsenic exposure from drinking-water in the Asian region. To protect people from the hazards of chronic arsenic poisoning, the Chinese Government has been providing low-arsenic drinking-water to some seriously-affected rural areas, such as Inner Mongolia autonomous province. Results of follow-up studies showed that both the average values of arsenic, including inorganic arsenic (iAs), monomethylated arsenic, dimethylated arsenic and trimethylated arsenic, and 8-hydroxydeoxyguanine in urine, decreased significantly after drinking low-arsenic water for one year, and arsenic-specific skin lesions also improved to some extent. However, a five-year follow-up study showed no more significant improvement of skin lesions, while the potential risk of arsenic-induced cancers after cutting off high-arsenic exposure was still uncertain and indefinite. The susceptibility of children compared to adults to chronic arsenic exposure and the need to re-evaluate the appropriate standard of arsenic in drinking-water were also discussed in this paper

Protective Role of Nuclear Factor E2-Related Factor 2 against Acute Oxidative Stress-Induced Pancreatic β

Oxidative stress is implicated in the pathogenesis of pancreatic β-cell dysfunction that occurs in both type 1 and type 2 diabetes. Nuclear factor E2-related factor 2 (NRF2) is a master regulator in the cellular adaptive response to oxidative stress. The present study found that MIN6 β-cells with stable knockdown of Nrf2 (Nrf2-KD) and islets isolated from Nrf2-knockout mice expressed substantially reduced levels of antioxidant enzymes in response to a variety of stressors. In scramble MIN6 cells or wild-type islets, acute exposure to oxidative stressors, including hydrogen peroxide (H2O2) and S-nitroso-N-acetylpenicillamine, resulted in cell damage as determined by decrease in cell viability, reduced ATP content, morphology changes of islets, and/or alterations of apoptotic biomarkers in a concentration- and/or time-dependent manner. In contrast, silencing of Nrf2 sensitized MIN6 cells or islets to the damage. In addition, pretreatment of MIN6 β-cells with NRF2 activators, including CDDO-Im, dimethyl fumarate (DMF), and tert-butylhydroquinone (tBHQ), protected the cells from high levels of H2O2-induced cell damage. Given that reactive oxygen species (ROS) are involved in regulating glucose-stimulated insulin secretion (GSIS) and persistent activation of NRF2 blunts glucose-triggered ROS signaling and GSIS, the present study highlights the distinct roles that NRF2 may play in pancreatic β-cell dysfunction that occurs in different stages of diabetes

Superficial nanocrystallization of the titanium alloy Ti6A14V : application to biomedical

Ce travail présente l’application et l’optimisation du procédé de nanocristallisation superficielle (Surface Mechanical Attrition Treatment ou SMAT) et du procédé duplex SMAT/nitruration sur l’alliage de titane Ti6A14V utilisé en chirurgie orthopédique. Le SMAT permet d’améliorer les propriétés mécaniques d’un matériau grâce à la formation d’une couche déformée en surface composée de très petits grains. Le procédé de nitruration quant à lui, augmente la résistance à l’usure d’un matériau par diffusion d’azote et création de nitrures à la surface d’un matériau. La comparaison de la résistance à l’usure du Ti6Al4V traité par différentes conditions de SMAT et de nitruration ont permis de restreindre l’étude à une condition (nommée C1). Ainsi, les mesures de rugosité ont montré une diminution de la rugosité des échantillons traités par SMAT (avec et sans nitruration) ainsi qu’une augmentation de la dureté en surface. Dans un deuxième temps, nous avons mis au point une méthodologie pour caractériser la microstructure des échantillons traités par SMAT C1 et traités par SMAT-nitrurés par microscopie électronique (MEB et MET). Ces études ont révélé que le traitement SMAT crée une zone déformée d’environ 60 μm avec des grains plus petits que dans le Ti6A14V brut, avec notamment des grains de 50 nm de diamètre en extrême surface. Lorsque le SMAT est couplé à la nitruration à basse température (375°C), l’épaisseur de la couche nitrurée diminue jusqu’à 20 μm tout en conservant des fins grains. En revanche, à haute température (730°C), la microstructure du SMAT est remplacée par des gros grains et des analyses par DRX indiquent que des nitrures se sont formés. L’augmentation de la dureté constatée peut être soit liée à la nanocristallisation générée par le SMAT, soit à la présence de nitrures à haute température. Enfin, des tests préliminaires de biocompatibilité indiquent que le Ti6A14V traité par SMAT reste biocompatible puisque les cellules MG 63 utilisées ont adhéré et proliféré sur les échantillons traités par SMAT. Nous avons également exploré la possibilité d’améliorer la biocompatibilité du Ti6A14V en le revêtant de matériaux bioactifs comme l’hydroxyapatite (HAP) ou le bio verre.This work presents the application and the optimization of the surface nanocrystallization process (Surface Mechanical Attrition Treatment or SMAT) and the duplex SMAT/nitriding process to the titanium alloy Ti6A14V used in orthopedic surgery. On the one hand, the SMAT improves the mechanical properties of a material through the formation at the surface of a deformed layer composed of very small grains. The nitriding process increases the wear resistance of a material by diffusion of nitrogen and creation of nitrides in the surface of a material. The comparison of wear resistance of Ti6A14V treated by different conditions of SMAT and nitriding has allowed us to limit our study to the condition referred to as C1. Thus, roughness measurements showed a decrease of roughness and an increase in hardness of the surface for the C1-SMAted and SMATed/nitrided samples compared to untreated Ti6A14V. In a second step, we have developed a methodology to characterize the microstructure of C1 SMATed and SMAT-nitrided samples by electron microscopy (SEM and TEM). These studies revealed that the C1 treatment created a deformed area of about 60 μm thick with smaller grains than the untreated Ti6Al4V samples, in particulars with about 50 nm diameter grains in the extreme surface. When SMAT and low temperature nitriding (375 ° C) were combined, the thickness of the deformed layer decreased to 20 μm but the small grains remained. On the contrary, at high nitriding temperatures (730 °C), the microstructure of SMAT was replaced by coarse grains whilst XRD analyses indicated that nitrides formed. We assume that the improvement in hardness is either related to the nanocrystallization generated by SMAT or to the presence of nitrides at 730 ° C. Finally, preliminary biocompatibility tests have indicated that SMATed Ti6Al4V is biocompatible since the MG-63 cells we used adhered and proliferated on SMATed surfaces. Additionally, we have also explored the coating of Ti6A14V with bioactive materials (hydroxyapatite and bioglass) to improve its biocompatibility

Nanocristallisation superficielle d'alliages de titane Ti6A14V (application au biomédical)

Ce travail présente l application et l optimisation du procédé de nanocristallisation superficielle (Surface Mechanical Attrition Treatment ou SMAT) et du procédé duplex SMAT/nitruration sur l alliage de titane Ti6A14V utilisé en chirurgie orthopédique. Le SMAT permet d améliorer les propriétés mécaniques d un matériau grâce à la formation d une couche déformée en surface composée de très petits grains. Le procédé de nitruration quant à lui, augmente la résistance à l usure d un matériau par diffusion d azote et création de nitrures à la surface d un matériau. La comparaison de la résistance à l usure du Ti6Al4V traité par différentes conditions de SMAT et de nitruration ont permis de restreindre l étude à une condition (nommée C1). Ainsi, les mesures de rugosité ont montré une diminution de la rugosité des échantillons traités par SMAT (avec et sans nitruration) ainsi qu une augmentation de la dureté en surface. Dans un deuxième temps, nous avons mis au point une méthodologie pour caractériser la microstructure des échantillons traités par SMAT C1 et traités par SMAT-nitrurés par microscopie électronique (MEB et MET). Ces études ont révélé que le traitement SMAT crée une zone déformée d environ 60 m avec des grains plus petits que dans le Ti6A14V brut, avec notamment des grains de 50 nm de diamètre en extrême surface. Lorsque le SMAT est couplé à la nitruration à basse température (375C), l épaisseur de la couche nitrurée diminue jusqu à 20 m tout en conservant des fins grains. En revanche, à haute température (730C), la microstructure du SMAT est remplacée par des gros grains et des analyses par DRX indiquent que des nitrures se sont formés. L augmentation de la dureté constatée peut être soit liée à la nanocristallisation générée par le SMAT, soit à la présence de nitrures à haute température. Enfin, des tests préliminaires de biocompatibilité indiquent que le Ti6A14V traité par SMAT reste biocompatible puisque les cellules MG 63 utilisées ont adhéré et proliféré sur les échantillons traités par SMAT. Nous avons également exploré la possibilité d améliorer la biocompatibilité du Ti6A14V en le revêtant de matériaux bioactifs comme l hydroxyapatite (HAP) ou le bio verre.This work presents the application and the optimization of the surface nanocrystallization process (Surface Mechanical Attrition Treatment or SMAT) and the duplex SMAT/nitriding process to the titanium alloy Ti6A14V used in orthopedic surgery. On the one hand, the SMAT improves the mechanical properties of a material through the formation at the surface of a deformed layer composed of very small grains. The nitriding process increases the wear resistance of a material by diffusion of nitrogen and creation of nitrides in the surface of a material. The comparison of wear resistance of Ti6A14V treated by different conditions of SMAT and nitriding has allowed us to limit our study to the condition referred to as C1. Thus, roughness measurements showed a decrease of roughness and an increase in hardness of the surface for the C1-SMAted and SMATed/nitrided samples compared to untreated Ti6A14V. In a second step, we have developed a methodology to characterize the microstructure of C1 SMATed and SMAT-nitrided samples by electron microscopy (SEM and TEM). These studies revealed that the C1 treatment created a deformed area of about 60 m thick with smaller grains than the untreated Ti6Al4V samples, in particulars with about 50 nm diameter grains in the extreme surface. When SMAT and low temperature nitriding (375 C) were combined, the thickness of the deformed layer decreased to 20 m but the small grains remained. On the contrary, at high nitriding temperatures (730 C), the microstructure of SMAT was replaced by coarse grains whilst XRD analyses indicated that nitrides formed. We assume that the improvement in hardness is either related to the nanocrystallization generated by SMAT or to the presence of nitrides at 730 C. Finally, preliminary biocompatibility tests have indicated that SMATed Ti6Al4V is biocompatible since the MG-63 cells we used adhered and proliferated on SMATed surfaces. Additionally, we have also explored the coating of Ti6A14V with bioactive materials (hydroxyapatite and bioglass) to improve its biocompatibility.REIMS-SCD-Bib. electronique (514549901) / SudocSudocFranceF

Combined surface treatment: surface nanocrystallisation and nitriding

International audienc

Biomatériaux : les apports d’un traitement de surface de nanocristallisation

International audienc

Current Research Problems of Chronic Arsenicosis in China

Chronic arsenicosis is a newly-emerged public-health issue in China and many other Asian countries. Over 200 million people are estimated to be at the risk of high arsenic exposure from drinking-water in the Asian region. To protect people from the hazards of chronic arsenic poisoning, the Chinese Government has been providing low-arsenic drinking-water to some seriously-affected rural areas, such as Inner Mongolia autonomous province. Results of follow-up studies showed that both the average values of arsenic, including inorganic arsenic (iAs), monomethylated arsenic, dimethylated arsenic and trimethylated arsenic, and 8-hydroxydeoxyguanine in urine, decreased significantly after drinking low-arsenic water for one year, and arsenic-specific skin lesions also improved to some extent. However, a five-year follow-up study showed no more significant improvement of skin lesions, while the potential risk of arsenic-induced cancers after cutting off high-arsenic exposure was still uncertain and indefinite. The susceptibility of children compared to adults to chronic arsenic exposure and the need to re-evaluate the appropriate standard of arsenic in drinking-water were also discussed in this paper