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1.
An electroencephalogram (EEG)-based brain–computer interface (BCI) speller allows a user to input text to a computer by thought. It is particularly useful to severely disabled individuals, e.g. amyotrophic lateral sclerosis patients, who have no other effective means of communication with another person or a computer. Most studies so far focused on making EEG-based BCI spellers faster and more reliable; however, few have considered their security. This study, for the first time, shows that P300 and steady-state visual evoked potential BCI spellers are very vulnerable, i.e. they can be severely attacked by adversarial perturbations, which are too tiny to be noticed when added to EEG signals, but can mislead the spellers to spell anything the attacker wants. The consequence could range from merely user frustration to severe misdiagnosis in clinical applications. We hope our research can attract more attention to the security of EEG-based BCI spellers, and more broadly, EEG-based BCIs, which has received little attention before.  相似文献   

2.
Open Source Software (OSS) has had a profound impact on the way in which software is developed and consequently on the perception of software development. This paper starts with a brief discussion of the eclectic techniques and processes, combinations of which may be used for OSS projects. A ‘real-world’ context will be examined using ‘Reflective Analysis’ focusing on the research and development team present within the Business, Logistics and Information Systems (BLIS) department at The University of Bolton. The reflective analysis explores some assumptions inherent in OSS development. Drawing on findings from experience, industry and background research, an attempt will be made to provide an insight into how in a small team, the use of OSS and associated techniques can lead to the successful development of software. Whilst early results show that smaller OSS projects may appear to have little or no formal structure with closer investigation it is clear this is not the case. Without at least some degree of management, the teams experience indicates that such projects may be prone to failure.  相似文献   

3.
彭伟  李慧  周欣怡 《科研管理》2020,41(12):257-266
悖论式领导是领导力领域最近兴起的研究热点，其相关研究正处于起步阶段。虽然已有研究表明悖论式领导对员工的态度与行为具有积极的影响，但悖论式领导影响员工创造力的作用机制尚未明晰。构建一个跨层次的被调节中介模型，从社会网络的视角探讨团队外部网络在悖论式领导与员工创造力关系之间所起的中介作用，并考察中庸思维对团队外部网络与员工创造力关系以及对悖论式领导通过团队外部网络影响员工创造力的间接效应的调节作用。基于51名直接上司和175名下属员工的配对调查数据，实证分析结果表明：悖论式领导对员工创造力具有显著的正向影响；悖论式领导通过影响团队外部网络，进而作用于员工创造力；中庸思维对团队外部网络与员工创造力之间的关系发挥跨层次调节效应；中庸思维对悖论式领导通过团队外部网络影响员工创造力的间接效应具有跨层次的调节作用。  相似文献   

4.
We have developed a microfluidics based sampling system for tissue analytics. The proof-of-concept of the sampling system was demonstrated by extracting lipid samples from tissue biopsies. The sample collection system consists of a disposable silicon based multiport microneedle integrated with polymer microfluidics. The polymethyl methacrylate polymer microfluidic chip has a 10 μl sample reservoir and actuation membranes for liquid pumping. A special automated robotic system was developed to control the positioning of the needle and the sampling procedure on preselected spots on the tissue. Real breast cancer tissue samples were used to test the feasibility of the sampling system. We successfully measured indicative cancer biomarkers from the tissue surface. Phosphatidylcholine and phosphoethanolamine were extracted from the tissue membrane with methyl tert-butyl ether solvent and detected by mass spectrometry. In the future, this tool could be used in characterization of preoperative biopsies and tumour tissues removed during surgery.  相似文献   

5.
This paper presents a vertically positioned microfluidic system made of poly(dimethylsiloxane) (PDMS) and glass, which can be applied as a microbubble column (μBC) for biotechnological screening in suspension. In this μBC, microbubbles are produced in a cultivation chamber through an integrated nozzle structure. Thus, homogeneous suspension of biomass is achieved in the cultivation chamber without requiring additional mixing elements. Moreover, blockage due to produced carbon dioxide by the microorganisms—a problem predominant in common, horizontally positioned microbioreactors (MBRs)—is avoided, as the gas bubbles are released by buoyancy at the upper part of the microsystem. The patterned PDMS layer is based on an optimized two-lithographic process. Since the naturally hydrophobic PDMS causes problems for the sufficient production of microbubbles, a method based on polyelectrolyte multilayers is applied in order to allow continuous hydrophilization of the already bonded PDMS-glass-system. The μBC comprises various microelements, including stabilization of temperature, control of continuous bubble formation, and two optical configurations for measurement of optical density with two different sensitivities. In addition, the simple and robust application and handling of the μBC is achieved via a custom-made modular plug-in adapter. To validate the scalability from laboratory scale to microscale, and thus to demonstrate the successful application of the μBC as a screening instrument, a batch cultivation of Saccharomyces cerevisiae is performed in the μBC and compared to shake flask cultivation. Monitoring of the biomass growth in the μBC with the integrated online analytics resulted in a specific growth rate of 0.32 h−1, which is almost identical to the one achieved in the shake flask cultivation (0.31 h−1). Therefore, the validity of the μBC as an alternative screening tool compared to other conventional laboratory scale systems in bioprocess development is proven. In addition, vertically positioned microbioreactors show high potential in comparison to conventional screening tools, since they allow for high density of integrated online analytics and therefore minimize time and cost for screening and guarantee improved control and analysis of cultivation parameters.  相似文献   

6.
The term ‘information’ is seldom given a careful definition and is in practice used in more than one sense. In particular there is often a failure to distinguish ‘information’ from concepts such as ‘knowledge’, ‘belief’ and ‘meaning’. One attempt to build a suitable conceptual scheme with a firm philosophical basis has been made by Dretske. In corporate contexts, the meaning and significance of information can be seen as lying in its contribution to the maintenance and development of ‘systems’ of activities. It follows that a competent analysis of corporate information requirements and a specification of the characteristics of data collection, communication and processing needed to satisfy them, both depend on an appropriate form of systems analysis. The methods used by Checkland and Wilson provide means of exploring the requirements, while the approaches of Beer and Espejo define patterns of information flow necessary for their realization. As advanced techniques of information processing develop, clearer understanding of such approaches and their theoretical basis will become important in exploiting their potential.  相似文献   

7.
陈明海 《科教文汇》2011,(19):66-69
道问题是中国美学的基本问题。从＂文质彬彬＂到＂文道合一＂,文道关系的发展演变得以显现。朱熹立足于＂理本气具＂、＂理一分殊＂的理学哲学体系,提出了＂文道合一＂的文道观。他对唐宋古文家＂文以明道＂、＂文以贯道＂、＂文与道俱＂以及理学前辈们＂文以载道＂、＂作文害道＂的文道观点进行了批判和发展,使文道关系的理论价值超越了先辈,从而实现了对中唐以来文道关系论争的真正总结。  相似文献   

8.
An adaptive sliding mode trajectory tracking controller is developed for fully-actuated robotic airships with parametric uncertainties and unknown wind disturbances. Based on the trajectory tracking model of robotic airships, an adaptive sliding mode control strategy is proposed to ensure the asymptotic convergence of trajectory tracking errors and adaptive estimations. The crucial thinking involves an adaptive scheme for the controller gains to avoid the off-line tuning. Specially, the uncertain physical parameters and unknown wind disturbances are rejected by variable structure control, and boundary layer technique is employed to avoid the undesired control chattering phenomenon. Computer experiments are performed to demonstrate the performance and advantage of the proposed control method.  相似文献   

9.
In this paper, some theorems are stated, which allow to design robust control laws without chattering, of type PD or PI, for uncertain nonlinear MIMO systems having a quite general structure, to track sufficiently regular trajectories with preassigned maximum error. The proposed control laws are easy to design and implement, above all for the robotic systems, because these laws can also be decentralized and they are based on two design parameters: the first related to the maximum eigenvalue of the inertia matrix from which the practical stability depends on, and the second related to the practical region of asymptotic stability (RAS), to the precision of the tracking error and to the convergence velocity of the tracking error to the desired neighborhood. If the trajectories to track are not sufficiently regular, suitable filtering laws are proposed for these trajectories, so as to facilitate the implementation of the controller and reduce the control action especially during the transient phase.Three significant examples of application in the terrestrial, sea transportation and robotic areas, well showing the simplicity of design and implementation of the controllers and their effectiveness, are reported.  相似文献   

10.
Despite widespread dissatisfaction with the quality of scientific information employed in planning and policy-making in public agencies, relatively little is known about the scientific information acquisition behaviors of public managers. The purpose of this paper is to facilitate research on scientific information acquisition in public agencies by suggesting that: (1) planning and policy-making are ‘policy technologies’ and share certain attributes with more traditional technologies; (2) many propositions developed in the literature on information flows in R&D labs are, therefore, helpful in structuring thinking about information flows in public agencies; and (3) it may be possible self-consciously to design social and organizational structures so as to enhance informal flows of scientific information. After gleaning some of the propositions concerning scientific information flows from the R&D management literature, an ‘ideal design’ approach is employed to develop a model in which the social and organizational structures of a public agency optimize scientific information flow.  相似文献   

11.
Smart wheelchairs based on brain–computer interface (BCI) have been widely utilized recently to address certain mobility problems for people with disability. In this paper, we present SmartRolling, an intuitive human–machine interaction approach for the direct control of robotic wheelchair that jointly leverages EEG signals and motion sensing techniques. Specifically, SmartRolling offers two wheelchair-actuation modes for users with different physical conditions: (1) head motion only — people who are severely disabled but able to do basic tasks using eyes and head, and (2) head and hands motion — in addition to type 1, people who can use functioning hands/arms for extra tasks. The system issues operation commands by recognizing different EEG patterns elicited by motor execution (ME) tasks including eye blink, jaw clench, and fist open/close, while at the same time estimates users’ steering intentions based on their facing direction by leveraging inertial measurements and computer vision techniques. The experiment results demonstrate that the proposed system is robust and effective to meets the individual’s needs and has great potential to promote better health.  相似文献   

12.
The emerging technologies on mobile-based diagnosis and bioanalytical detection have enabled powerful laboratory assays such as enzyme-linked immunosorbent assay (ELISA) to be conducted in field-use lab-on-a-chip devices. In this paper, we present a low-cost universal serial bus (USB)-interfaced mobile platform to perform microfluidic ELISA operations in detecting the presence and concentrations of BDE-47 (2,2′,4,4′-tetrabromodiphenyl ether), an environmental contaminant found in our food supply with adverse health impact. Our point-of-care diagnostic device utilizes flexible interdigitated carbon black electrodes to convert electric current into a microfluidic pump via gas bubble expansion during electrolytic reaction. The micropump receives power from a mobile phone and transports BDE-47 analytes through the microfluidic device conducting competitive ELISA. Using variable domain of heavy chain antibodies (commonly referred to as single domain antibodies or Nanobodies), the proposed device is sensitive for a BDE-47 concentration range of 10−3–104 μg/l, with a comparable performance to that uses a standard competitive ELISA protocol. It is anticipated that the potential impact in mobile detection of health and environmental contaminants will prove beneficial to our community and low-resource environments.  相似文献   

13.
Enrichment of rare cell populations such as Circulating Tumor Cells (CTCs) is a critical step before performing analysis. This paper presents a polymeric microfluidic device with integrated thick Carbon-PolyDimethylSiloxane composite (C-PDMS) electrodes designed to carry out dielectrophoretic (DEP) trapping of low abundance biological cells. Such conductive composite material presents advantages over metallic structures. Indeed, as it combines properties of both the matrix and doping particles, C-PDMS allows the easy and fast integration of conductive microstructures using a soft-lithography approach while preserving O2 plasma bonding properties of PDMS substrate and avoiding a cumbersome alignment procedure. Here, we first performed numerical simulations to demonstrate the advantage of such thick C-PDMS electrodes over a coplanar electrode configuration. It is well established that dielectrophoretic force (FDEP) decreases quickly as the distance from the electrode surface increases resulting in coplanar configuration to a low trapping efficiency at high flow rate. Here, we showed quantitatively that by using electrodes as thick as a microchannel height, it is possible to extend the DEP force influence in the whole volume of the channel compared to coplanar electrode configuration and maintaining high trapping efficiency while increasing the throughput. This model was then used to numerically optimize a thick C-PDMS electrode configuration in terms of trapping efficiency. Then, optimized microfluidic configurations were fabricated and tested at various flow rates for the trapping of MDA-MB-231 breast cancer cell line. We reached trapping efficiencies of 97% at 20 μl/h and 78.7% at 80 μl/h, for 100 μm thick electrodes. Finally, we applied our device to the separation and localized trapping of CTCs (MDA-MB-231) from a red blood cells sample (concentration ratio of 1:10).  相似文献   

14.
This study proposes a capillary dielectrophoretic chip to separate blood cells from a drop of whole blood (approximately 1 μl) sample using negative dielectrophoretic force. The separating efficiency was evaluated by analyzing the image before and after dielectrophoretic force manipulation. Blood samples with various hematocrits (10%–60%) were tested with varied separating voltages and chip designs. In this study, a chip with 50 μm gap design achieved a separation efficiency of approximately 90% within 30 s when the hematocrit was in the range of 10%–50%. Furthermore, glucose concentration was electrochemically measured by separating electrodes following manipulation. The current response increased significantly (8.8-fold) after blood cell separation, which was attributed not only to the blood cell separation but also to sample disturbance by the dielectrophoretic force.  相似文献   

15.
The new knowledge acquisition and sharing stage represents the start of the organization's overall knowledge creation process. It is especially important for contributing to the critical foundation of organizational knowledge creation. This study explores the relationship between employees’ knowledge acquisition sources and the patterns of knowledge-sharing behaviors. We use structural equation modeling to test a sample of R&D professionals from high-tech companies in Taiwan. Data analysis suggests that most employees prefer to acquire knowledge from, and share knowledge with, their team members. This implies that greater familiarity between team members and strengthened cooperative relationships foster productivity. Furthermore, employees should be encouraged to participate in professional communities in order to acquire new knowledge. Knowledge acquired via these channels will facilitate the sharing of R&D knowledge within the organization.  相似文献   

16.
BCI系统的研究,经过二十多年的发展,已经慢慢地走出实验室,面向应用。为更方便对运动功能障碍人士进行帮助,把传统BCI系统移植到移动平台上就显得尤为重要。本文利用AR模型把时域信号转换到频域,然后利用Fisher距离进行特征提取,利用定义的线性分类器进行分类。结果表明,利用本方法能很好地识别三种不同运动想象类型。  相似文献   

17.
The problem addressed in this article is to use Bertram Brookes' ‘fundamental equation’ as a starting off-point for a conceptual exercise whose purpose is to set out a method for calculating the information content of an information process. The knowledge structure variables in the Brookes' equation are first operationalized, following principles set out in Claude Shannon's mathematical theory of communication. The set of ‘a priori’ alternatives and the a priori probabilities assigned to each member of the set by the person undergoing the information process is the operational definition of the variable ‘K[S]’ from the ‘fundamental equation,’ which represent the person's knowledge structure ‘before’ the information process takes place. The set of ‘a posteriori’ alternatives and the revised probabilities assigned to each member of the set by the person undergoing the information process is the operational definition of the Brookes' variable ‘K[S + ΔS],’ which is the person's knowledge structure ‘after’ the information process takes place. To illustrate how the variables can be determined, an example of a information process is used from a recent real-life archeological discovery.  相似文献   

18.
许成磊  段万春 《科研管理》2015,36(10):153-160
为应对"动机不纯"、"近亲繁殖"、"拉帮结派"等多种团队管理难题,结构化、主题化、动态化实现创新团队社会资本关系的系统整合优化,在梳理提炼社会资本关系界面内涵、存在形式、关联特征和表现特质的基础上,结合对社会资本关系强度差序化作用及和谐管理主题辨识的思考,提出应用社会资本关系平等度划分社会资本关系管理主题的思路,给出无层次/交叉层次/有层次三种类型社会资本关系的概念。借鉴能够系统整合团队复杂界面关联的ANP方法,构造改进现有累积前景方法、能够实现和谐主题动态辨识及优化的CPT-ANP决策方法,并进行案例应用。案例应用结果表明,所构建的网络整合优化方法有效可行,能够为应对系列团队管理难题提供决策依据。  相似文献   

19.
IntroductionIt is common for patients to switch between several healthcare providers. In this context, the long-term follow-up of medical conditions based on laboratory test results obtained from different laboratories is a challenge. The measurement uncertainty in an inter-laboratory context should also be considered in data mining research based on routine results from randomly selected laboratories. As a proof-of-concept study, we aimed at estimating the inter-laboratory reference change value (IL-RCV) for exemplary analytes from publicly available data on external quality assessment (EQA) and biological variation.Materials and methodsExternal quality assessment data of the Reference Institute for Bioanalytics (RfB, Bonn, Germany) for serum creatinine, calcium, aldosterone, PSA, and of whole blood HbA1c from campaigns sent out in 2019 were analysed. The median CVs of all EQA participants were calculated based on 8 samples from 4 EQA campaigns per analyte. Using intra-individual biological variation data from the EFLM database, positive and negative IL-RCV were estimated with a formula based on log transformation under the assumption that the analytes under examination have a skewed distribution.ResultsWe estimated IL-RCVs for all exemplary analytes, ranging from 13.3% to 203% for the positive IL-RCV and - 11.8% to - 67.0% for the negative IL-RCV (serum calcium - serum aldosterone), respectively.ConclusionExternal quality assessment data together with data on the biological variation – both freely available – allow the estimation of inter-laboratory RCVs. These differ substantially between different analytes and can help to assess the boundaries of interoperability in laboratory medicine.  相似文献   

20.
In this article and two other articles which conceptualize a future stage of the research program (Leide, Cole, Large, & Beheshti, submitted for publication; Cole, Leide, Large, Beheshti, & Brooks, in preparation), we map-out a domain novice user’s encounter with an IR system from beginning to end so that appropriate classification-based visualization schemes can be inserted into the encounter process. This article describes the visualization of a navigation classification scheme only. The navigation classification scheme uses the metaphor of a ship and ship’s navigator traveling through charted (but unknown to the user) waters, guided by a series of lighthouses. The lighthouses contain mediation interfaces linking the user to the information store through agents created for each. The user’s agent is the cognitive model the user has of the information space, which the system encourages to evolve via interaction with the system’s agent. The system’s agent is an evolving classification scheme created by professional indexers to represent the structure of the information store. We propose a more systematic, multidimensional approach to creating evolving classification/indexing schemes, based on where the user is and what she is trying to do at that moment during the search session.  相似文献   

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