The astrocyte as a gatekeeper of synaptic information transfer

We present a simple biophysical model for the coupling between synaptic transmission and the local calcium concentration on an enveloping astrocytic domain. This interaction enables the astrocyte to modulate the information flow from presynaptic to postsynaptic cells in a manner dependent on previous activity at this and other nearby synapses. Our model suggests a novel, testable hypothesis for the spike timing statistics measured for rapidly firing cells in culture experiments.     

The need for virtual information managers in education

In this paper, the authors analyse how educational institutions behave in relation with the contents available through the Web. They also reflect on the features of the currently available information managers, from an educational point of view. They found there is a lack of tools for information management at low scale when it has to be used as a resource for teaching and learning whether at secondary or university level. Finally, they propose a solution, which consists of naming a ‘small virtual educational library’ (SVEL), and they show how it works in Physics education context.     

The PRODNET cooperative information management for industrial virtual enterprises

When designing an IT platform aimed at supporting industrial virtual enterprises (VEs), certain issues related to information management requirements become especially challenging, such as the physical distribution of data, the enterprise autonomy and privacy enforcement, access rights to shared information, and data visibility levels, among others. In the ESPRIT project PRODNET II, a federated database architecture was designed and implemented as the base support framework to effectively manage these issues associated with the sharing and exchange of information in the VE environment. In this paper, first the general information management requirements identified for the VE network in the PRODNET II project are described, and then the challenging design issues behind the development of the components of the federated information management system are presented.     

新旧系统切换中数据转换的研究与实现

数据转换是信息系统升级、新旧信息系统切换过程中的重要工作。按照软件工程的方法,对数据转换过程中的各个环节进行定义,保证通过有效的数据转换工作使历史数据资源在新系统中得以利用。     

IDL与VC信息相互传递的实现方法

为了准确传递和保存IDL可视化数据信息,实现语言之间的互通性、资源共享性、数据信息的多样性、调用格式的不同性,基于解析函数调用的方法 ,运用动态链接库和一系列的子类函数获取数据,使IDL与VC之间相互转换信息,可通过VC直接对遥感影像进行处理,为应用系统的研发提供了一种新方法。试验实例证明,该方法能简单有效地将IDL与VC有机地结合在一起,实现了信息相互传递,并通过C直接对遥感影像进行操作处理。     

Wearable vibrotactile systems for virtual contact and information display

This paper presents a development history of a wearable, scalable vibrotactile stimulus delivery system. This history has followed a path from desktop-based, fully wired systems, through hybrid approaches consisting of a wireless connection from the host computer to a body-worn control box and wires to each tactor, to a completely wireless system employing Bluetooth technology to connect directly from the host to each individual tactor unit. Applications for such a system include delivering vibrotactile contact cues to users of virtual environments, providing directional cues in order to increase situational awareness in both real and virtual environments, and for general information display in wearable contexts. Through empirical study, we show that even a simple configuration, such as eight tactors arrayed around the torso, can be effective in increasing situational awareness in a building-clearing task, compared to users who perform the same task without the added cues.     

Hierarchical Newton and least squares iterative estimation algorithm for dynamic systems by transfer functions based on the impulse responses

This paper develops a parameter estimation algorithm for linear continuous-time systems based on the hierarchical principle and the parameter decomposition strategy. Although the linear continuous-time system is a linear system, its output response is a highly nonlinear function with respect to the system parameters. In order to propose a direct estimation algorithm, a criterion function is constructed between the response output and the observation output by means of the discrete sampled data. Then a scheme by combining the Newton iteration and the least squares iteration is builded to minimise the criterion function and derive the parameter estimation algorithm. In light of the different features between the system parameters and the output function, two sub-algorithms are derived by using the parameter decomposition. In order to remove the associate terms between the two sub-algorithms, a Newton and least squares iterative algorithm is deduced to identify system parameters. Compared with the Newton iterative estimation algorithm without the parameter decomposition, the complexity of the hierarchical Newton and least squares iterative estimation algorithm is reduced because the dimension of the Hessian matrix is lessened after the parameter decomposition. The experimental results show that the proposed algorithm has good performance.     

基于视频数据和传递熵的鱼群信息传递网络构建

鱼群中的个体如何通过信息传递从而达到一致的群体运动状态,至今还没有刻画这一现象的统一数学模型.本文阐述了一种利用视频数据和传递熵构建鱼群中个体间信息传递网络的方法.首先用实验获取斑马鱼集群的视频数据,并采用计算机视觉跟踪的方法获取鱼群中每个个体的位置和运动速度,然后利用传递熵计算个体两两之间的信息传递关系,在此基础上构建了鱼群信息传递网络.通过网络分析,揭示了鱼群中个体间的信息交互个数与信息传播速度之间的关系,进一步发现了鱼群信息传递网络中的频繁子结构.本文提供了一种利用探测时间序列间因果关系建立鱼群信息传递网络的方法,为鱼群信息传递研究提供了一种新的思路.     

Trust in information sources: seeking information from people,documents, and virtual agents

The notion of trust has been virtually absent from most work on how people assess and choose their information sources. Based on two empirical cases this study shows that software engineers and users of e-commerce websites devote a lot of attention to considerations about the trustworthiness of their sources, which include people, documents, and virtual agents. In the project-based software engineering environment trust tends to be a collaborative issue and the studied software engineers normally know their sources first-hand or have them recommended by colleagues. Outside this network people are cautious and alert to even feeble cues about source trustworthiness. For example, users of e-commerce websites—generally perceived as single-user environments—react rather strongly to the visual appearance of virtual agents, though this is clearly a surface attribute. Across the two cases people need access to their sources in ways that enable them to assess source trustworthiness, access alone is not enough.     

虚拟维修训练系统的信息交互功能实现技术

在多种虚拟维修训练系统中,要求高效地反映当前维修程序的执行阶段,及时掌握训练过程中的仿真运行阶段,提出基于Vega环境的虚拟维修训练信息交互实现技术。     

Perceived orientation in physical and virtual environments: changes in perceived orientation as a function of idiothetic information available

Two experiments examined perceived spatial orientation in a small environment as a function of experiencing that environment under three conditions: real-world, desktop-display (DD), and head-mounted display (HMD). Across the three conditions, participants acquired two targets located on a perimeter surrounding them, and attempted to remember the relative locations of the targets. Subsequently, participants were tested on how accurately and consistently they could point in the remembered direction of a previously seen target. Results showed that participants were significantly more consistent in the real-world and HMD conditions than in the DD condition. Further, it is shown that the advantages observed in the HMD and real-world conditions were not simply due to nonspatial response strategies. These results suggest that the additional idiothetic information afforded in the real-world and HMD conditions is useful for orientation purposes in our presented task domain. Our results are relevant to interface design issues concerning tasks that require spatial search, navigation, and visualization.     

The change in user and IT dynamics: Blogs as IT-enabled virtual self-presentation

Using the blogosphere as an enabling IT environment, this paper investigates how self-concept influences virtual self-presentation behavior and the use of IT artifacts. Self-presentation theory is adapted from the social psychology literature to develop a theoretical research model of virtual self-presentation. We tested the research model and hypotheses with data collected from 312 bloggers. Structural equation analysis of this data reveals a nomological net of self-concept leading to IT-enabled virtual self-presentation and the use of IT artifacts. Our findings provide a new perspective of users as heterogeneous individuals who have various self-concepts that change the sequence and dynamics among users, IT artifacts, and tasks. In contrast to traditional systems, in the social context of virtual self-presentation, users are the primary and essential drivers who determine vaguely defined tasks and systems.     

Browsing a document collection represented in two- and three-dimensional virtual information space

This paper reports a study of information retrieval performance using an interface in which documents were represented by objects in a virtual environment. Spatial location was determined by semantic content, with inter-object distance representing semantic similarity of documents. The quality of spatial-semantic mapping was manipulated as was the number of dimensions (two versus three) in which document nodes were arranged. Participants were required to browse the information space and identify all documents relevant to a specified topic. Results indicated that participants were able to use three-dimensional spatial mapping of semantic information to facilitate task performance, with performance being better when the quality of the mapping was higher. Strategy differences were identified, with participants adopting a more ‘exhaustive’ approach when searching two-dimensional node arrangements, and a more ‘focused’ approach for three-dimensional arrangements. Cognitive ability was not strongly associated with task performance, but participants of relatively lower cognitive ability tended to out-perform those of higher cognitive ability in three-dimensional conditions. Possible reasons for these findings are discussed.     

Analysis, processing and transfer of dynamic images in virtual reality models

Multi-agent virtual reality models and methods for their design based on video capturing, analysis, processing, and transfer of dynamic images of real-life scenes are considered. The main applied results concern virtual reality models and man-machine interface for multi-agent robotic systems that assist neurosurgeons. This work was supported by the Russian Foundation for Basic Research, projects nos. 03-01-00224a and 05-01-08044-ofi, and Ministry for Education and Science of the Russian Federation, state contract no. 37.029.11.0027.     

Data and information as property

Digital technologists concern themselves with data - conventional representations of facts or ideas - and with machines for storing, transforming, and transmitting it. Although computing professionals also concern themselves with digital technology, they focus primarily on people and information-the meaning that people give to data. The use of data to convey information is vitally important to our social systems. This is underlined by recent research showing that dogs are much more able to get meaning from data than chimpanzees, which probably explains why dogs make better pets. The sharing of meaning has been the foundation of social development. The different data technologies have been used both to empower and to constrain members of our society as technology and society have evolved together. Computing professionals should thus always be sensitive to the social uses of data and information. They should also be alert to legal developments related to using data and to digital technology's role in producing data.     

基于超声波的无线携能通信研究

无线携能通信是将无线能量传输与无线信息传输相结合的产物。近年来,以无线电波作为媒介的携能通信研究十分火热,而以超声波作为媒介的方式却没有得到足够关注。从超声波的传能机制出发,提出超声波换能器的设计要求;从超声波的通信机制出发,研究超声波通信的调制方式及信道特性;从功率分配角度出发,建立了速率-能量折衷模型,提出了适用于不同应用场景的动态功率分配算法,建立了基于超声波的无线携能通信系统模型。     

CBTC系统信息安全传输的研究

分析了基于标准协议安全数据传输的协议层,提出了基于IEEE802.11的CBTC数据传输系统的模型,并且提出了实现该CBTC通信系统的安全方案,包括传输相关保护方案的具体实现和接入保护所采取的IPSec措施。     

Enhancing virtual environment spatial awareness training and transfer through tactile and vestibular cues

Haptic interaction has been successfully incorporated into a variety of virtual environment (VE) systems, yet designing multimodal VE training systems remains challenging as each cue incorporated during training should maximise learning and training transfer. This study examined the impact of incorporating two independent, spatialised tactile cues and vestibular cues into a military VE training environment with the goal of empirically examining whether such cues could enhance performance within the training environment and also that knowledge and skills gained during training could transfer to another environment. The results showed that tactile cues enhanced spatial awareness and performance during both repeated training and within a transfer environment, yet there were costs associated when two independent tactile cues were presented during training. In addition, results suggest that spatial awareness benefits from a tactile point indicator may be impacted by vestibular cues, as performance benefits were seen when tactile cues were paired with head tracking. To fully realise training potential, it is essential to determine how best to leverage multimodal capacity of VE training systems by identifying how multimodal training cues may advance knowledge, skills and attitudes of trainees. Results from this study provide design guidelines for incorporating tactile cues in VE training environments to enhance spatial awareness.     

Assessing forest structural and physiological information content of multi-spectral LiDAR waveforms by radiative transfer modelling

The concept for a multi-spectral, full-waveform canopy LiDAR instrument was tested by simulating return waveforms using a model providing ecological sound tree structure (TREEGROW) and a model of leaf optical properties (PROSPECT). The proposed instrument will take measurements at four different wavelengths, which were chosen according to physiological processes altering leaf reflectance and transmittance. The modelling was used to assess both the structural and physiological information content such an instrument could provide, especially whether the normally structure-dominated return waveform would pick up small changes in reflectance at the leaf level. Multi-spectral waveforms were simulated for models of single Scots pine trees of different ages and at different stages of the growing season, including chlorophyll concentration induced changes in leaf optical properties. It was shown that the LiDAR waveforms would not only capture the tree height information, but would also pick up the seasonal and vertical variation of NDVI computed from two of the four MSCL wavelengths inside the tree canopy. The instrument concept was further tested in a simulation of a virtual forest stand constructed of 74 trees of different ages according to measurements taken on a field site being 20 by 20 meter in size. A total of 1521 NDVI profiles were computed and mean NDVI corrected backscatter was compared to the actual canopy profile of the virtual stand. The profiles picked up the seasonal variation of chlorophyll within the canopy, while the return of ground remained unchanged from June to September. Thus, it was shown that a MSCL instrument would be able to separately pick up the physiology of canopy and understorey and/or soil. It was found that occlusion would mask the lower parts of the canopy volume within the stand and the seasonal variation of this occlusion effect was quantified, being larger in September, when the absorption of canopy elements is higher. In addition, it could be demonstrated that a new multi-wavelength LiDAR predictor variable was able to significantly improve the retrieval accuracy of photosynthetically active biomass opposed to using a single-wavelength LiDAR alone.     

基于Web服务的信息安全虚拟实验系统的研究与实现

开发的信息安全虚拟实验平台采用虚拟主机技术在单台计算机上实现多台虚拟机网络攻击和防护的模拟，实验者可通过协议分析软件，实时观看分析攻击过程。教师和学生可通过Internet访问在线实验系统，进行实验创作和实验预习、在线自测。建立了私有UDDI注册中心，实现了Web Service的动态查询、调用及调用失败后的恢复，提高了实验系统的服务质量，实际运行情况良好。