Echocardiography can detect cloth cover tears in fully covered Starr-Edwards valves: a long-term clinical and echocardiographic study

Smoothelin is a constituent of the cytoskeleton specific for smooth muscle cells (SMCs) in a broad range of species. It has been postulated that smoothelin represents a marker of highly differentiated, contractile SMCs. Here, we present data on the presence of smoothelin in the human vascular system that support this hypothesis. For this purpose, smoothelin distribution was studied (1) during vasculogenesis of the placenta, (2) in normal adult blood vessels, and (3) in atherosclerotic lesions. Smoothelin was first observed in placental tissue at approximately week 10 to 11 of gestation. In full-term placenta, it was found in the SMCs of vessels in the large stem villi and in the chorionic plate. Furthermore, it was present in the fetal arteries of smaller stem villi, but it was not found in the veins. In adult blood vessels, a small population of aortic (approximately 10%) and large muscular artery (approximately 30% to 50%) SMCs was positive for smoothelin. In general, smoothelin and desmin were coexpressed in the same SMCs, but expression of desmin appeared to be less abundant. However, the majority of SMCs in these blood vessels were smoothelin- and desmin negative but expressed vimentin, whereas alpha-smooth muscle actin (alpha-SMA) was present in all SMCs. The SMCs in the media of small muscular arteries were positive for smoothelin and desmin (> 95%), whereas the vimentin-positive SMC type was scarce. Smoothelin was absent in capillaries, pericytic venules, and small veins but was occasionally observed in the SMCs of large veins. Thus, the distribution of smoothelin in the SMCs of the vascular system appears to be limited to blood vessels that are capable of pulsatile contraction. In atherosclerotic femoral arteries, smoothelin-positive cells were detected in the media, the atheromatous plaque, and the intimal thickening. Smoothelin-positive cells were present primarily at the luminal portion of advanced lesions. The presence of a considerable number of such smoothelin-positive cells at that location may indicate that these plaques are no longer expanding.     

Shock waves in boiling liquids

The behaviour of shock waves in a vapour-liquid medium of bubble structure was studied. The general laws of a wave process were established, basic similarity criteria were determined. The existence of different propagation regimes of the pressure waves was revealed. The feasibility of the formation of steep shock waves of monotonous or oscillatory structure in a boiling liquid was shown. The condition for the existence of such shock waves in a vapour-liquid medium was determined.     

AlGaN/PZT探测器的研制及其性能

本文报道了一种新型紫外红外应用的探测器的设计、制备及其性能。探测器由蓝宝石衬底上生长的p-GaN/i-GaN/n-Al0.3Ga0.7N/SiO2/LaNiO3/PZT/Pt多层结构组成。分别测量了紫外和红外的性能。紫外部分,光谱响应范围在302-363nm波段;在波长355nm,探测器零偏响应率为0.064A/W;I-V测量表明零偏暗电流为-1.57×10-12A;该探测器的探测率为1.81×1011cmHz1/2W-1。红外部分,在波长4μm处,探测器响应率为1.58×105cmHz1/2W-1。     

基于改进传感器模式噪声提取模型的源相机识别

针对当前基于传感器模式噪声(sensor pattern noise,SPN)提取模型处理压缩 视频来源检测的识别效果较差问题,提出一种基 于多尺度变换域自适应维纳滤波和一种加权最大似然估计的改进SPN提取模型。 首先干预视 频的编解码过程,在编解码器的环路滤波模块前提取视频帧,然后将视频帧输入双密度双树 复小波变换 自适应维纳滤波模型中提取噪声残差,最后使用加权最大似然估计从噪声残差中估计得到SPN。在公共视频源取证数据库VISION上进行测试比较,实验结果表明所提出的改进SPN提取 模型在ROC曲线和Kappa统计系数两种评价指标上的识别效果优于 传统SPN提取算法。     

Correlation between the intergranular brittleness and precipitation reactions during isothermal aging of an Fe–Ni–Mn maraging steel

Evolution of the intergranular brittleness of an Fe–10Ni–7Mn (weight pct) maraging steel was correlated with precipitation reactions during isothermal aging at 753 K. Intergranular brittleness of the Fe–Ni–Mn steel raises after aging treatment which occurs catastrophically at zero tensile elongation in the underaged and peakaged steels. The intergranular failure is attributed to grain boundary weakening due to the formation of coarse grain boundary precipitates associated with solute-depleted precipitate-free zones during isothermal aging. Further, evidences of planar slip bands were found within the grains of a peakaged specimen loaded by tensile deformation. Those inhomogeneously deformed bands were identified to apply large strain localization in the soft precipitate-free zones at grain boundaries which is assumed to fascinate microcracks initiation at negligible macroscopic strains in the underaged and peakaged steels. During further aging, concurrent reactions including (i) overaging of matrix precipitates, (ii) spheroidization of grain boundary precipitates, (iii) growth of precipitate-free zone in width and (iv) diffusional transformation to austenite take place which increase tensile ductility after prolonged aging.     

Microwave nondestructive evaluation of dielectric materials with a metamaterial lens

A novel microwave nondestructive evaluation (NDE) sensor was developed in an attempt to increase the sensitivity of the microwave NDE method for detection of defects small relative to a wavelength. The sensor was designed on the basis of a negative index material (NIM) lens. Characterization of the lens was performed to determine its resonant frequency, index of refraction, focus spot size, and optimal focusing length (for proper sample location). A sub-wavelength spot size (3 dB) of 0.48λ was obtained. The proof of concept for the sensor was achieved when a fiberglass sample with a 3 mm diameter through hole (perpendicular to the propagation direction of the wave) was tested. The hole was successfully detected with an 8.2 cm wavelength electromagnetic wave. This method is able to detect a defect that is 0.037λ. This method has certain advantages over other far field and near field microwave NDE methods currently in use.     

A study on expertise of agents and its effects on cooperative Q-learning.

Cooperation in learning (CL) can be realized in a multiagent system, if agents are capable of learning from both their own experiments and other agents' knowledge and expertise. Extra resources are exploited into higher efficiency and faster learning in CL as compared to that of individual learning (IL). In the real world, however, implementation of CL is not a straightforward task, in part due to possible differences in area of expertise (AOE). In this paper, reinforcement-learning homogenous agents are considered in an environment with multiple goals or tasks. As a result, they become expert in different domains with different amounts of expertness. Each agent uses a one-step Q-learning algorithm and is capable of exchanging its Q-table with those of its teammates. Two crucial questions are addressed in this paper: "How the AOE of an agent can be extracted?" and "How agents can improve their performance in CL by knowing their AOEs?" An algorithm is developed to extract the AOE based on state transitions as a gold standard from a behavioral point of view. Moreover, it is discussed that the AOE can be implicitly obtained through agents' expertness in the state level. Three new methods for CL through the combination of Q-tables are developed and examined for overall performance after CL. The performances of developed methods are compared with that of IL, strategy sharing (SS), and weighted SS (WSS). Obtained results show the superior performance of AOE-based methods as compared to that of existing CL methods, which do not use the notion of AOE. These results are very encouraging in support of the idea that "cooperation based on the AOE" performs better than the general CL methods.