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Autonomous path planning represents a cornerstone technology for enabling planetary rovers to carry out exploration missions on extraterrestrial planets. This technology facilitates planetary rovers in navigating safely and efficiently toward their mission goal. However, the special conditions of extraterrestrial planetary environments pose significant challenges for autonomous path planning compared with those faced by ground-based mobile robots. These challenges include communication delays and bandwidth limitations between the planetary rover and the ground control station, limited light, unknown and unpredictable terrain, distinct environmental features, and the difficulty of accurately modeling interactions between the rover wheels and the ground. Therefore, addressing how to generate a safe, efficient, and reasonable traversable path for a planetary rover under conditions of incomplete environmental data and uncertain positioning is a focal point of current research. This paper reviews advancements in perception map construction and autonomous path planning for planetary rovers, examining both research progress and engineering applications. First, this paper summarizes advances in perception map construction methods that rely on binocular vision. This method uses stereo vision to generate parallax maps, which in turn help construct a digital elevation model of the planet’s surface. Stereo matching algorithms are typically used to acquire parallax maps. The discussion includes an analysis of two main types of methods: region-based matching algorithms and feature-based matching algorithms. Second, the paper classifies existing autonomous path-planning methods for planetary rovers into two categories: those based on cost evaluation and those leveraging machine learning. As a typical representative of cost-evaluation–based path planning methods, the optional arc-based autonomous path planning method is spotlighted for its algorithmic principles and iterative applications in ongoing planetary rover missions. Furthermore, the potential of A* heuristic search algorithm, rapidly-exploring random tree star (RRT*) algorithm, and fast marching method(FMM) algorithms for enhancing planetary rover path planning is explored in a categorical manner. The application of machine learning in autonomous path planning for planetary rovers is also reviewed. Such methods are classified into two groups: end-to-end path planning methods and auxiliary approaches leveraging machine learning. Ultimately, based on the above analysis of the key technologies of planetary rover autonomous path planning, the paper identifies and discusses future research directions for improving autonomous path planning methods for planetary rovers. These include enhancing perception capabilities, improving optional arc paths, reducing slippage, integrating multiple path planning methods, and strengthening the use of machine learning.

Stroke is a disease with a high disability rate， and often leads to limb dysfunction， especially upper limb motor dysfunction， which significantly affects the patients’ abilities and quality of life. With patients' increasing demand for functional recovery， various therapeutic techniques of rehabilitation medicine have been rapidly developed. As an important active central intervention technology， motor imagery training can be initiated by the patient's brain and activate the sensorimotor network to accelerate the repair of limb functions. The development of preventive medicine has promoted the continuous evolution of the concept of rehabilitation. The strategies of full cycle functional protection and disability prevention have been improved and developed in the clinical and scientific research practice of upper limb rehabilitation after stroke. The motor imagery training can activate the upper limb motor neural network in the early stage of stroke to prevent functional loss； In the recovery period， it can accelerate the neural function remodeling and reduce the upper limb disability； In the later stage after stroke， it can improve the performance of upper limb function in daily life， thus helping patients return to family life and society. This article reviews the research progress in recent years in China and abroad in the application of motor imagery training for the full cycle function protection and disability prevention of stroke.

Airworthiness regulations are key for guaranteeing the safety of civil aviation products and a significant indication of a nation’s aviation power. A well-developed airworthiness regulation system is an effective technical and management means by which a country with an advanced aviation industry ensures the safety of its civil aviation products and occupies the broadest market share while using International Civil Aviation Organization (ICAO) rules. As major national science and technology projects for large aircraft, aero-engines, and gas turbines are implemented, it is imperative for China to further improve its airworthiness regulation system. In this study, we clarify the implications of aero-engine airworthiness regulations and summarize the problems regarding aero-engine airworthiness regulations both in China and abroad. Based on this, the formation strategy and technical path for the next-generation airworthiness regulations of aero-engines are explored from the perspectives of ICAO and China’s civil aviation industry. The formulation strategy emphasizes the requirement for system safety, and specific principles include an equivalent level of safety, clear logic, international compatibility, and local applicability. Moreover, a new top-level framework for the aero-engine airworthiness regulations is proposed; it inherits the international lessons learned, ensures a high safety standard, and adapts to the progress of system safety technologies of aero-engines. Furthermore, we suggest that China should continuously deepen the research, simultaneously expand application, and coordinate industry development, thus to promote the construction of the aero-engine airworthiness regulation system in China.

Considering the coexistence of matrix pores and fractures, the coexistence of discrete fractures and continuous medium fractures, stress sensitivity effect and the influence of three zones with different physical properties, this paper presents a transient pressure analysis model for wells intersecting with discrete fractures n the ultra-deep and ultra-light pressure fractured tight sandstone gas reservoirs. The Laplace transformation, Pedrosas transformation and perturbation technique are adopted to solve the proposed model, and the type curves are calculated and plotted by programming. Flowing periods were identified according to the characteristics of type curves and the sensitivity analysis of influential factors were conducted. The results show that up to fourteen typical flowing periods can be observed on the type curves of the fractured wells in this kind of complex gas reservoirs. When there is a stress sensitive effect, the position of the pressure derivative curves during the middle and later flowing periods will be higher. The longer the discrete fractures encountered by the gas well, the lower the position of the derivative curve during the linear flow stage and other flowing stages of the fracture network system in zone I. The mobility ratio mainly affects the height of the pressure derivative curves during the pseudo- radial flow and inter-porosity flow stages. The smaller the storage capacity ratio, the deeper the corresponding concave on the pressure derivative curve. The smaller the inter-porosity flow coefficients of each region, the later the corresponding concave on the pressure derivative curve appears. This work can provide support for well testing interpretation techniques for the ultra-deep and ultra-high pressure naturally fractured complex gas reservoirs. [ABSTRACT FROM AUTHOR]

BACKGROUND: For the treatment of intertrochanteric fracture in elderly patients, if there is no operative contraindication, surgical treatment is recommended. Operative methods include internal fixation and joint replacement. Surgical techniques are mature, but the choice of surgical methods is controversial. OBJECTIVE: To compare the efficacy of artificial femoral head arthroplasty and proximal femoral nail antirotation in elderly patients with injured lateral wall femoral intertrochanteric fracture so as to provide the basis of clinical method selection and to provide the original data for the systematic analysis of large sample. METHODS: According to the case criterion, 48 cases of AO classification of type A2.2, A2.3 intertrochanteric fractures were selected in Department of Orthopedics, the 71 Group Army Hospital of Chinese PLA from January 2012 to December 2017. They were divided into femoral head arthroplasty group (n=29) and proximal femoral nail antirotation group (n=19). All patients signed the informed consent. This study was approved by the Hospital Ethics Committee. The patients were followed up for 1-3 years. Operation time, bleeding volume, hospitalization expenses, the incidence of complications, and Harris hip score at 1 month and 1 year after the surgery were compared between the two groups. RESULTS AND CONCLUSION: (1) After statistical analysis, operation time was significantly shorter in the femoral head arthroplasty group than in the proximal femoral nail antirotation group (P < 0.05). There was no statistically significant in bleeding volume between the two groups (P > 0.05). The cost of hospitalization was significantly more in the femoral head arthroplasty group than in the proximal femoral nail antirotation group (P < 0.05}. (2) Harris hip score was significantly better in the femoral head arthroplasty group than in the proximal femoral nail antirotation group at 1 month after operation (P < 0.05}. There was no significant difference in Harris hip score between the two groups at 1 year after operation (P > 0.05). (3) There was no significant difference in the incidence of complications between the two groups (P > 0.05}. (4) For the patients over 70 years old with intertrochanteric fracture of injured lateral wall, artificial femoral head replacement has the advantages of early getting out of bed, high quality of life and quick recovery of joint function. It is suggested to choose artificial femoral head replacement first. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect and significance of down-regulation of Oct4 gene on biological characteristics of MDA-MB-231 breast cancer stem cells. Methods Breast cancer cell line MDA-MB-231 cells were used in this study. Breast cancer stem cells were isolated and enriched by serum-free culture. The obtained stem cells were identified through calculating the percentages of CD44 and CD24 stem cells b\ FACS and evaluating die paclitaxel resistance in vitro and tumorigenicity in mice. RT-PCR, real-time PCR (qPCR) and Western blot were used to detect 0ct4 expression. RNA interference was applied to induce 0cl4 down-regulation. The interference experiment set up a control group (no siRNA transfection), negative control group (negative siRNA group, transfection of siRNA sequences without any interfering effect on the cells) and 0ct4 siRNA group (transfection of siRNA with interfering effect on the 0ct4 gene). Methyl thiazolyl tetrazolium (MTT) and Transwell chamber tests were conducted to detect the proliferation and invasion ability of MDA-MB-231 breast cancer stem cells after 0ct4 knock-down, and paclitaxel inhibition test was applied to evaluate drug resistance of MDA-MB-231 breast cancer stem cells after 0ct4 knock-down. Results MDA-MB-231 breast cancer stem cells grew as spheres cultured in serum-free suspension. MDA-MB-231 breast cancer stem cells showed a higher percentage of CD44+ /CD24-/low cells (97.2%) than that in MDA-MB-231 breast cancer cells (76.6%) (P<0.05). The tumor size in mice inoculated with MDA-MB-231 breast cancer stem cells was ( 124.60± 13.65) mm , significantly larger than that of mice inoculated with breast cancer cells (68.20±9.99 mm3) (P= 0.0007). MDA-MB-231 breast cancer stem cells were less sensitive to paclitaxel inhibition than MDA-MB-231 breast cancer cells showing by 50% inhibitory concentration (IC50) [(4.40±0.48) μg/ml vs. (8.20±0.34) μg/ml, P<0.05]. However, the expression of transcriptional factors Oct4 was higher in MDA-MB-231 breast cancer stem cells than that in breast cancer cells (P<0.05). The proliferation potential of MDA-MB-231 breast cancer stem cells with Oct4 siRNA interference was significantly lower than that in the negative siRNA and control groups (P<0.05) from the interference was penetrated cells third day. The invasion ability of MDA-MB-231 breast cancer stem cells with Oct4 siRNA obviously reduced than dial in the control and negative siRNA groups shown by number o [ (46.52±2.58) vs. (79.67±3.85) and (77.29±2.13) , P<0.05 for both]. As for resistance to paclitaxel, IC50 of MDA-MB-231 breast cancer stem cells with Oct4siRNA interference was significantly decreased [ (4.48±0.22) μg/ml] compared with that in the control [ (7.99±0.59) μg/ml] and negative siRNA group [(8.10±0.68) μg/ml] (P< 0.05 for both). Conclusions MDA-MB-231 breast cancer cells are successfully obtained by serum-free culture. The proliferation potential, invasion ability and drug resistance of breast cancer stem cells were down-regulated by Oct4 gene knock-down. [ABSTRACT FROM AUTHOR]