儿童根据环境中的可靠信息来认路

本文考察3-4岁儿童在圆形空间中重新定位和找回玩具的能力。让儿童把玩具放到一个路标物体里,闭眼转圈后找回玩具,观察儿童寻找玩具的位置,并将它跟睁眼转圈后儿童寻找玩具的位置比较,从而考察儿童的认路能力。实验结果说明儿童不能利用路标物体所形成的几何结构和具有延展性信息的表面来认路,但可以根据环境中的可靠信息未认路,即路标物体的独特性信息。因此,我们认为儿童是根据环境中的可靠信息——路标物体的独特性来认路的。

小小坦克会认路

别看它其貌不扬，人家可是聪明的认路坦克！

认路大王

一群小蚂蚁在草地上发现了几块面包屑，激动地跑了过去。

认路也遗传

常有人抱怨自己记性差，认不清路，记不住陌生人的面孔。美国科学家最近的一份研究发现，人们对于长相和地点的识别能力会受到遗传基因的影响。这项研究成果已刊登在了美国《神经科学杂志》（Journal of Neuroscience）上。

Hippocampal HMGB1/TLR4 Pathway Mediates Cognitive Dysfunction in Chronic Stress Mice

Objective Chronic stress can induce cognitive dysfunction,but the underlying mechanisms remain unknown.Studies have confirmed that the high mobility group box 1/Toll-like receptor 4(HMGB1/TLR4)pathway is closely associated with cognitive impairment.Therefore,this research aimed to explore whether the HMGB1/TLR4 pathway involves in chronic stress-induced cognitive dysfunction.Methods The chronic unpredictable mild stress(CUMS)mouse model was established by randomly giving different types of stress every day for four consecutive weeks.Cognitive function was detected by novel object recognition test,Y-maze test,and Morris water maze test.The protein expressions of HMGB1,TLR4,B-cell lymphoma 2(BCL2),and BCL2 associated X(BAX)were determined by Western blot.The damage of neurons in the hippocampal CA1 region was observed by hematoxylin-eosin(HE)staining.Results The protein expressions of HMGB1 and TLR4 were significantly increased in the hippocampus of chronic stress mice.Furthermore,inhibition of the HMGB1/TLR4 pathway induced by ethyl pyruvate(EP,a specific inhibitor of HMGB1)and TAK242(a selective inhibitor of TLR4)treatment attenuated cognitive impairment in chronic stress mice,according to the novel object recognition test,Y-maze test,and Morris water maze test.In addition,administration of EP and TAK242 also mitigated the increase of apoptosis in the hippocampus of chronic stress mice.Conclusion These results indicate that the hippocampal HMGB1/TLR4 pathway contributes to chronic stress-induced apoptosis and cognitive dysfunction.

Spectrum allocation game of directional transmission in multi-hop cognitive radio networks

The spectrum allocation for links in multi-hop cognitive radio networks is addressed.The links rent the vacant licensed bands offered by primary users for implementing directional transmission.To minimize the individual cost,the links share the licensed band and rental fee.An interference model for the directional transmission in cognitive radio networks is proposed to formulate the cooperative and dynamic behavior of the links using the theory of hedonic game,called spectrum allocation game.The game is proved to converge to the core stable state indicating that all links satisfy with their current conditions and do not deviate from their coalitions.Numerical results show that the game improves spectral efficiency and contributes to reducing the individual cost of the links.

Metacognition in Solving Process of Basic Electric Circuit ProblemmComparison of Metacognitive Characteristics between Non-major and Major Students in Electric Engineering

There are learners who cannot solve practical problems in spite of mastering basic scientific knowledge and formula necessary for the solution. One of the reasons might be attributed to the lack in metacognitive abilities. The aim of this study was to compare the metacognitive characteristics between non-major and major students in electric engineering and clarify the difference of metacognitive process between these two groups when solving basic problems of electronic circuit. In the experiment, the solving process was compared between non-major and major students in electric engineering using five basic problems. We found that the scores on prediction of result and confidence of own answer differed significantly between non-major and major students, and inferred that the difference of performance was due to the lack in metacognitive ability, especially the plan and the execution abilities. Both prediction of results and confidence of own answer were also found to play a significant role in effective problem solving as important components （subsystems） of metacognition.

Link Maintenance Scheme for OFDM-Based Cognitive Radio Ad Hoc Networks

Transmission among the cognitive users(CUs)' is always interrupted by the primary users(PUs)' reclaim of the spectrum and the fading effect of wireless channels.To maintain reliable continuous communication among CUs,an efficient scheme for link maintenance in OFDM-based cognitive radio Ad Hoc networks is proposed in this paper.In the scheme,redundant sub-channels(RSC) are employed by CUs to tackle the outage problem caused by the PUs' reclaim of the spectrum and wireless fading effect in the transmission.Meanwhile,backup sub-channels(BSC) are arranged to help select sub-channels with better channel quality.Additionally,to lower the overhead and improve the accuracy of the spectrum sensing,a partial sensing module is designed to enable the CUs to inherit and update the original idle spectrum list until it expires.Simulation results show that the proposed scheme can realize higher throughput and lower sensing overhead with slight reduction of the forced termination probability(FTP) performance compared to the existing approaches.

Suggestion of Criteria and Certification Process to Secure the Safety of Railway Software

One of the significant differences between the digital system and the analog system is software. The software takes charge of the functions and the management of the digital system. Nowadays railway equipment has begun to be designed and implemented based on digital technology with online and real time performance to achieve high speed and high density operation. The software is designed, coded and implemented into the system, and controls hardware components in order to satisfy the functional requirements of the system. As the functions that are implemented by software are increased, it becomes very difficult to predict the soil-ware failures because of its complexity. Therefore, it has become one of the key issues how to assure that the sottware is reliable, safe and secure. In this paper, the safety criteria are suggested to secure the software safety for the field of railway system. Characteristic of railway software and review safety related standards are analyzed. The authors also suggest development methodology and certification procedure for the developer and assessor to easily make safety critical railway software with following the safety criteria.

Hierarchical Cognition Cycle for Cognitive Radio Networks

Cognitive radio(CR) can bring about remarkable improvement in spectrum utilization.Different cognition cycles have been proposed in recent years.However,most of the existing works only emphasize functional or operational aspects of cognition cycle,regardless of other indispensable aspects and the connection between them.To deal with the emerging situation of "data rich,information vague,knowledge poor" in cognitive radio networks(CRNs),we propose the hierarchical cognition cycle(HCC) as a new transdisciplinary research field in this paper.HCC investigates a fundamental problem,which is how to manage available resources in the complex environment to meet various demands in CRN.A comprehensive theoretical framework of HCC is established in terms of the core,the essence loop,the function loop,the operation loop,and the external loop of HCC.The reduction of uncertainty in CRN is studied and several new metrics in HCC are defined.Furthermore,a few research challenges ahead are presented as well.

A QoS Mobicast-based dynamic clustering secure multicast scheme for large-scale tracking sensornets

Most of the existing security Mobicast routing protocols are not suitable for the monitoring applications with higher quality of service （QoS） requirement. A QoS dynamic clustering secure multicast scheme （QoS-DCSMS） based on Mobicast and multi-level IxTESLA protocol for large-scale tracking sensornets is presented in this paper. The multicast clusters are dynamically formed according to the real-time status of nodes, and the cluster-head node is responsible for status review and certificating management of cluster nodes to ensure the most optimized QoS and security of multicast in this scheme. Another contribution of this paper is the optimal QoS security authentication algorithm, which analyzes the relationship between the QoS and the level Mofmulti-level oTESLA. Based on the analysis and simulation results, it shows that the influence to the network survival cycle （＇NSC） and real-time communication caused by energy consumption and latency in authentication is acceptable when the optimal QoS security authentication algorithm is satisfied.