Review of micro-expression spotting and recognition in video sequences

Facial micro-expressions are short and imperceptible expressions that involuntarily reveal the true emotions that a person may be attempting to suppress,hide,disguise,or conceal.Such expressions can reflect a person's real emotions and have a wide range of application in public safety and clinical diagnosis.The analysis of facial micro-expressions in video sequences through computer vision is still relatively recent.In this research,a comprehensive review on the topic of spotting and recognition used in micro expression analysis databases and methods,is conducted,and advanced technologies in this area are summarized.In addition,we discuss challenges that remain unresolved alongside future work to be completed in the field of micro-expression analysis.

Long-term surface water changes and driving cause in Xiong'an,China:from dense Landsat time series images and synthetic analysis

China's government statement recently reported the plan of constructing Xiong'an New Area, which aims to phase out some extra capital functions from Beijing and to explore an innovative urban development mode with the priority in eco-environmental protection. The New Area is located in the semi-arid North China Plain(NCP) and is home to NCP's largest natural freshwater wetland, Baiyangdian Lake. A comprehensive realization of surface water dynamics would be crucial for policy-makers to outline a sustainable environment development strategy for New Area. In this study, we used a total of 245 time slices of cloud-free Landsat images to document the continuous changes of water bodies within Xiong'an City during 1984-2016 and to provide detailed evidence of water presence and persistency states and changes under the influences of climate change and human actions. Our results reveal that the New Area water body areas varied dramatically during the past 33 years, ranging from 0.44 km^2 in April 1988 to317.85 km^2 in February 1989. The change of surface water area was not characterized by a monotonically decreasing tendency. The evolution processes can be divided into four sub-stages: the first extreme desiccation in mid-1980 s, the wet stage with the most extensive inundation areas and strong inter-annual fluctuations from late-1988 to late 1999, another desiccation stage in early 2000 s, and the overall recovering stage between 2007 and 2016. We also mapped the maximum water inundation extents and frequencies of all-season, pre-wet season(February-May) and post-wet season(September-December) for the 33 years and different sub-periods. Although there is good agreement between time series of surface water area evolution in the New Area and station-based precipitation and evaporation variations, multiple lines of evidences reviewed in previous research indicate that the degraded Baiyangdian Lake was also tightly associated with human activities from various aspects, including dam construction, groundwater extraction, agricultural irrigation, etc. We highlighted the current status of exploring the driving mechanism of surface water changes and existing problems, and then offer recommendations.

高活性间充质干细胞干预猕猴卵巢衰老的研究

目的研究一种高活性间充质干细胞(HA-MSCs)对衰老猕猴卵巢结构与功能的干预作用。方法分别使用TeSR-E8培养基和含10%胎牛血清的DMEM/F12培养基从青年猕猴骨髓中分离、扩增得到猕猴HA-MSCs与骨髓间充质干细胞(BMSCs),流式细胞仪检测细胞表面标志物,并进行成脂、成骨和成软骨诱导分化能力鉴定。然后将这2种细胞按1×10^(7)个细胞/kg的剂量,1日1次,连续3 d静脉输注给卵巢衰老猕猴,于治疗前1天、治疗后1、2、3、5个月检测外周血抗苗勒氏管激素(AMH)水平,治疗后第5个月将猕猴安乐死,HE染色观察卵巢的组织病理结构,Masson染色评价卵巢纤维化程度变化,免疫组织化学染色检测卵巢p16、p21衰老相关蛋白的表达水平。两组间比较采用t检验,多组间比较采用单因素方差分析,组间两两比较采用Tukey方法。结果HA-MSCs呈短小梭形,核质比高,形态均一。BMSCs体积较大,呈典型的成纤维细胞形态,有少量杂细胞。HA-MSCs的成脂、成骨和成软骨分化能力均强于BMSCs。与老年模型组比较,HA-MSCs治疗组在治疗后2个月内AMH水平[(1.85±0.21)比(0.29±0.15)ng/mL]增加,该组卵巢组织可见各级卵泡,纤维化程度降低(P均<0.001)。与老年模型组比较,BMSCs治疗组在治疗后1个月时AMH水平[(1.26±0.28)比(0.36±0.16)ng/mL]增加,与HA-MSCs治疗组比较,BMSCs治疗组在治疗后2个月时AMH水平[(1.85±0.21)比(0.60±0.20)ng/mL]降低,该组可见少量未成熟卵泡及原始卵泡,纤维化程度降低(P均<0.001)。老年模型组AMH水平最低,卵巢组织偶见闭锁卵泡,广泛纤维化。卵巢p16、p21蛋白表达水平在老年模型组最高,HA-MSCs治疗组最低,BMSCs治疗组次之。结论HA-MSCs提高衰老卵巢的储备能力,减轻卵巢纤维化,减少卵巢衰老相关蛋白的表达,重启卵泡生成功能,在治疗卵巢衰老上相较BMSCs效果更佳。

Direction controllable inverse transition radiation from the spatial dispersion in a graphene-dielectric stack

Transition radiation(TR) induced by electron–matter interaction usually demands vast accelerating voltages, and the radiation angle cannot be controlled. Here we present a mechanism of direction controllable inverse transition radiation(DCITR) in a graphene-dielectric stack excited by low-velocity electrons. The revealed mechanism shows that the induced hyperbolic-like spatial dispersion and the superposition of the individual bulk graphene plasmons(GPs) modes make the fields, which are supposed to be confined on the surface, radiate in the stack along a special radiation angle normal to the Poynting vector. By adjusting the chemical potential of the graphene sheets, the radiation angle can be controlled. And owing to the excitation of bulk GPs, only hundreds of volts for the accelerating voltage are required and the field intensity is dramatically enhanced compared with that of the normal TR. Furthermore, the presented mechanism can also be applied to the hyperbolic stack based on semiconductors in the infrared region as well as noble metals in the visible and ultraviolet region.Accordingly, the presented mechanism of DCITR is of great significance in particle detection, radiation emission,and so on.

Ensemble projections of climate and streamflow in a typical basin of semi-arid steppes in Mongolian Plateau of 2021-2100

The Kherlen River is the main water source for Hulun Lake,the largest lake in northern China.Due to reduced inflow from the Kherlen River,Hulun Lake experienced rapid shrinkage at the beginning of the 21st century,posing a serious threat to the ecological security of northern China.However,there is still a significant lack of projections regarding future climate change and its hydrological response in the Kherlen River basin.This study analyzed the projected climate and streamflow changes in the Kherlen River basin,a vital yet vulnerable international semi-arid steppes type basin.A combination of multi-model ensemble projection techniques,and the soil and water assessment tool(SWAT)model was employed to examine the spatio-temporal changes in precipitation,temperature,streamflow,and the associated uncertainties in the basin.The temperature(an increase of 1.84-6.42℃)and the precipitation(an increase of 15.0-46.0 mm)of Kherlen River basin are projected to increase by 2100,leading to a rise in streamflow(1.08-4.78 m^(3) s^(-1)).The upstream of the Kherlen River exhibits remarkable increasing trends in precipitation,which has a dominant influence on streamflow of Kherlen River.Noteworthy increases in streamflow are observed in April,August,September,and October compared to the reference period(1971-2000).These findings suggest a partial alleviation of water scarcity in the Kherlen River,but also an increased likelihood of hydrological extreme events.The projected temperature increase in the Kherlen River basin exhibits the smallest uncertainty,while more pronounced uncertainties are found in precipitation and streamflow.The spread among the results of CMIP6 models is greater than that of CMIP5 models,with lower signal-to-noise ratio(SNR)values for temperature,precipitation,and streamflow.