Showing papers by "Concordia University published in 2009"

Space shift keying modulation for MIMO channels

Abstract: In this paper, we present space shift keying (SSK) as a new modulation scheme, which is based on spatial modulation (SM) concepts. Fading is exploited for multiple-input multiple-output(MIMO) channels to provide better performance over conventional amplitude/phase modulation (APM) techniques. In SSK, it is the antenna index used during transmission that relays information, rather than the transmitted symbols themselves. This absence of symbol information eliminates the transceiver elements necessary for APM transmission and detection (such as coherent detectors). As well, the simplicity involved in modulation reduces the detection complexity compared to that of SM, while achieving almost identical performance gains. Throughout the paper, we illustrate SSK's strength by studying its interaction with the fading channel. We obtain tight upper bounds on bit error probability, and discuss SSK's performance under some non-ideal channel conditions (estimation error and spatial correlation). Analytical and simulation results show performance gains over APM systems (3 dB at a bit error rate of 10-5), making SSK an interesting candidate for future wireless applications. We then extend SSK concepts to incorporate channel coding, where in particular, we consider a bit interleaved coded modulation (BICM) system using iterative decoding for both convolutional and turbo codes. Capacity results are derived, and improvements over APM are illustrated (up to 1 bits/s/Hz), with performance gains of up to 5 dB.

When is PBL More Effective? A Meta-synthesis of Meta-analyses Comparing PBL to Conventional Classrooms

Abstract: Problem-based learning (PBL) has been utilized for over 40 years in a variety of diff erent disciplines. Although extensively researched, there is heated debate about the eff ectiveness of PBL. Several meta-analyses have been conducted that provide a synthesis of the eff ects of PBL in comparison to traditional forms of instruction. This study used a qualitative meta-synthesis approach to compare and contrast the assumptions and fi ndings of the meta-analytical research on the eff ectiveness of PBL. Findings indicated that PBL was superior when it comes to long-term retention, skill development and satisfaction of students and teachers, while traditional approaches were more eff ective for short-term retention as measured by standardized board exams. Implications are discussed.

A model of knowledge‐sharing motivation

Abstract: In this article, I present a model of knowledge-sharing motivation based on a combination of the theory of planned behavior (TPB) and self-determination theory (SDT), along with a review of research supporting the model and suggestions for future research and methodologies to study knowledgesharing behavior. I also give suggestions for designing five important human resource management (HRM) practices, including staffing, job design, performance and compensation systems, managerial styles, and training. © 2009 Wiley Periodicals, Inc.

Cosmopolitanism, Consumer Ethnocentrism, and Materialism: An Eight-Country Study of Antecedents and Outcomes

Abstract: Although there is a consensus that industries are globalizing, the notion that consumer attitudes and behaviors worldwide are likewise homogenizing remains disputed. Despite widespread discourse on this topic, there is a dearth of empirical investigations. This international research examines similarities and differences with respect to the nature of three consumer attitudinal dispositions: cosmopolitanism, consumer ethnocentrism, and materialism. The authors cross-culturally compare demographic antecedents with these dispositions, as well as behavioral outcomes. They test the validation of the construct measures and associated hypotheses using survey data drawn from consumers in eight countries and structural equation modeling techniques, including multigroup analysis. Empirical findings broadly support the cross-cultural applicability of the constructs, though the links to the various demographic antecedents vary considerably from sample to sample. The role of each construct on behavior also va...

Gender Dimensions of Brand Personality

Abstract: Although masculinity and femininity are personality traits relevant to brands, their measurement and contribution to branding theory and practice have not been examined. This article describes the development and validation of a two-dimensional scale measuring masculine and feminine brand personality that is discriminant with regard to existing brand personality dimensions and scales measuring masculinity and femininity as human personality traits. This scale is applied to show that (1) spokespeople in advertising shape masculine and feminine brand personality perceptions; (2) brand personality–self-concept congruence in terms of masculine and feminine brand personality and consumers' sex role identity positively influences affective, attitudinal, and behavioral brand-related consumer responses; and (3) masculine and feminine brand personality lends itself to the creation of brand fit in a brand extension context, which in turn leads to more positive brand extension evaluations and increased purc...

Controlled Synthesis and Water Dispersibility of Hexagonal Phase NaGdF4:Ho3+/Yb3+ Nanoparticles

Abstract: The luminescence properties of hexagonal sodium gadolinium fluoride nanoparticles co-doped with Ho3+ and Yb3+ (NaGdF4:Ho3+/Yb3+), prepared using a thermal decomposition synthesis route, were evaluated following 980 nm excitation. The synthesized nanoparticles were easily dispersed in nonpolar solvents, showed an extremely narrow particle distribution, and were determined to have a mean diameter of 15.6 ± 1.2 nm. The predominantly green upconversion emission was observed to increase with increasing Ho3+ concentration due to an enhanced energy transfer (ET) from the neighboring Yb3+ ions. Post-synthesis, the nanoparticles were dispersed in water via modification of the capping oleic acid (OA) ligand. Upconversion emission intensity was observed to decrease upon dispersion in aqueous media likely due to an increase in nonradiative decay pathways. A total ligand exchange with poly(acrylic acid) (PAA) resulted in slightly more intense upconversion emission relative to oxidation of the OA to azelaic acid.

Critical Success Factors of CRM Technological Initiatives

Abstract: As an increasing number of organizations realize the importance of becoming more customer-centric in today's competitive economy, they are also discovering that they must deliver authentic customer knowledge across multiple organizational functions and at all customer touch points. This paper compiles the critical success factors of customer relationship management (CRM) technological initiatives realized by 57 large organizations in Canada. The data analysis is performed using structural equation modeling techniques such as PLS. Resume Evoluant dans une economie fort competitive, un nombre croissant d'organisations realisent l'importance de mieux comprendre leurs clients. Elles decouvrent alors qu'elles peuvent gerer les connaissances acquises a leur sujet lors des contacts pris avec eux, et les integrer adequatement aux multiples fonctions organisationnelles. Cet article relate les facteurs critiques de succes necessaires lors de l'implantation d'initiatives technologiques supportant la gestion de la relation client (GRC). L'analyse des resultats obtenus aupres de 57 grandes organisations canadiennes est realisee en testant plusieurs equations structurelles a l'aide de la methode des moindres carres partiels (PLS).

Legitimation Strategies Used in Response to Environmental Disaster: A French Case Study of Total SA's Erika and AZF Incidents

Abstract: This paper presents a case study examining the environmental disclosure decisions and practices of Total SA (hereafter, Total), one of the largest integrated oil and gas companies in the world. Because the company has a substantial international presence and operates in environmentally sensitive industries, management is constantly exposed to ethical and social issues. The company faced two major environment-related disasters: (1) the sinking of the Erika tanker, leading to a major oil spill along the Atlantic coast of Bretagne in 1999; and (2) the 2001 deadly explosion of the AZF chemical plant in the suburb of Toulouse, France. In this case study I aim at investigating the strategies employed by Total to defend and downplay its environmental performance and activities related to these incidents. The case is framed within legitimacy theory, originating from the notion of a ‘social contract’ between organizations and society. Findings generally indicate that Total used communication strategies to legitima...

Computer Anxiety in E-Learning: The Effect of Computer Self-Efficacy.

Abstract: It has been reported that as many as fifty percent of adults, including first-year University students, have some sort of computer-related phobia This report demonstrates that the use of computers still has some unpleasant side effects despite the Internet boom in the past decade Past research shows that computer anxiety influences how users perceive ease of use of an information system However, few have investigated the role of computer self-efficacy in mediating computer anxieties on perceived ease of use Therefore, in this study we base our contribution on the variables of computer self-efficacy and computer anxieties These two variables are believed to impact an individual’s use of computers and performance for computer-based tasks Anxiety has been argued to impact computer-based learning by affecting levels of self-efficacy anchored in social learning and outcome expectation theories Self-efficacy is determined by levels of anxiety such that reduced anxiety and increased experience improves performance indirectly by increasing levels of self-efficacy In this study, we investigate the influence of computer anxiety on perceived ease of use and the mediating effect of computer self-efficacy on this relationship, within an e-learning context A survey methodology approach was used in this study using 18 items for 3 constructs (perceived ease of use, anxiety, and self-efficacy) Survey data from 645 university students were analyzed The psychometric properties of the items and constructs were validated followed by the assessment of mediation of computer self efficacy Results from the use of a learning management system indicate that computer self-efficacy plays a significant role in mediating the impact of anxiety on perceived ease of use This role is observed by computer selfefficacy (1) reducing the strength and significance of the impact of anxiety on perceived ease of use and (2) having a strong and significant relationship with computer anxiety The findings demonstrate the importance of self-efficacy as a mediator between computer anxiety and perceived ease of use of a learning management system (LMS) With the continuous development of richer and more integrated interfaces, anxieties about learning to use the new interface and executing tasks effectively becomes of primary importance Limitations and suggestions for future research are elaborated

Social disclosure, legitimacy theory and the role of the state

Abstract: Purpose – The principal objective of this paper is to expand the scope of legitimacy theory (LT) through a detailed analysis of the links that exist between the legitimising strategies of firms and the characteristics of the political environment in which they are developed. Designs/methodology/approach – A discourse analysis was performed on the social and environmental disclosure (SED) of a multinational in the automotive sector with an established presence in Spain, in the context of the relational dynamics between the firm/society/state. Different channels of information were compared to capture both the official discourse as represented in the annual reports of the multinational and the discourse of employees and the State as represented in the media. Findings – The results of the research show that the firm under study used SED strategically to legitimise a new production process through the manipulation of social perceptions, and that this strategy was supported implicitly and explicitly through ideological alignment with the State. Research limitations/implications – Despite a widely‐held assumption of a pluralist political context, the State is presented here as aligning itself with corporate management as opposed to the welfare concerns of employees. Thus, future research calling for regulation of SED should preface such calls with consideration of the orientation of the State. Originality/value – In contrast with the dominant approach to LT that considers the relationship of the firm with its stakeholders, the present study widens the scope of LT to consider the interplay between firm legitimating strategies and state support for such strategies.

Fiber-wireless (FiWi) access networks: A survey

Abstract: This article provides an up-to-date survey of hybrid fiber-wireless (FiWi) access networks that leverage on the respective strengths of optical and wireless technologies and converge them seamlessly. FiWi networks become rapidly mature and give rise to new powerful access network solutions and paradigms. The survey first overviews the state of the art, enabling technologies and future developments of wireless and optical access networks, respectively, paying particular attention to wireless mesh networks and fiber to the home networks. After briefly reviewing some generic integration approaches of EPON and WiMAX networks, several recently proposed FiWi architectures based on different optical network topologies and WiFi technology are described. Finally, technological challenges toward the realization and commercial adoption of future FiWi access networks are identified.

It's Time to Vote: The Effect of Matching Message Orientation and Temporal Frame on Political Persuasion

Abstract: What political candidates say during their campaign and when they say it are critical to their success In three experiments, we show that abstract, “why”-laden appeals are more persuasive than concrete, “how”-laden appeals when voters' decision is temporally distant; the reverse is true when the decision is imminent, and these results are strongest among those who are politically uninformed These effects seem to be driven by a match between temporal distance and the abstractness of the message that leads to perceptions of fluency, and the ensuing “feels right” experience yields enhanced evaluations of the focal stimulus

A Soft Error Tolerant 10T SRAM Bit-Cell With Differential Read Capability

Abstract: We propose a quad-node ten transistor (10 T) soft error robust SRAM cell that offers differential read operation for robust sensing. The cell exhibits larger noise margin in sub-0.45 V regime and 26% less leakage current than the traditional soft error tolerant 12 T DICE SRAM cell. When compared to a conventional 6 T SRAM cell, the proposed cell offers similar noise margin as the 6 T cell at half the supply voltage, thus significantly saving the leakage power. In addition, the cell exhibits 98% lower soft error rate than the 6 T cell in accelerated neutron radiation tests carried out at TRIUMF on a 32-kb SRAM implemented in 90-nm CMOS technology.

Near-Infrared-to-Blue Upconversion in Colloidal BaYF5:Tm3+, Yb3+ Nanocrystals

Abstract: Tetragonal barium yttrium fluoride (BaYF5) nanocrystals doped with 0.5 mol % Tm3+ and 15 mol % Yb3+ (BaYF5:Tm3+, Yb3+) were synthesized using the thermal decomposition method yielding rectangular-shaped nanocrystals (15 nm × 5 nm) that can (up)convert near-infrared light to higher energies such as blue, via a process known as upconversion. The upconversion spectrum of the BaYF5:Tm3+, Yb3+ nanocrystals, following excitation with 980 nm, revealed that the upconverted blue emission from the 1G4 → 3H6 transition was more intense than the infrared 3H4 → 3H6 emission at high excitation densities (90 W/cm2) contrary to what is normally observed for Tm3+/Yb3+ codoped nanomaterials. On the other hand, the infrared emission dominates at lower excitation densities (15 W/cm2) demonstrating a lack of excited Yb3+ ions to carry on the upconversion beyond the 3H4 excited state to the 1G4 excited state. A saturation of the upconversion process was observed in the power dependence studies at excitation densities above 57 ...

Varieties of Asian capitalism : toward an institutional theory of Asian enterprise

Abstract: In this paper we respond to calls for an institution-based perspective on strategy. With its emphasis upon mimetic, coercive, and normative isomorphism, institutional theory has earned a deterministic reputation and seems an unlikely foundation on which to construct a theory of strategy. However, a second movement in institutional theory is emerging that gives greater emphasis to creativity and agency. We develop this approach by highlighting co-evolutionary processes that are shaping the varieties of capitalism (VoC) in Asia. To do so, we examine the extent to which the VoC model can be fruitfully applied in the Asian context. In the spirit of the second movement of institutional theory, we describe three processes in which firm strategy collectively and intentionally feeds back to shape institutions: (1) filling institutional voids, (2) retarding institutional innovation, and (3) deploying institutional escape. We outline the key contributions contained in the articles of this Special Issue and discuss a research agenda generated by the VoC perspective.

Corporate disclosure of environmental capital expenditures: a test of alternative theories

Abstract: In this study, we examine three potential explanations for the corporate choice to disclose environmental capital spending amounts. We investigate, first, whether the disclosure appears to be a function of the materiality of the spending and we find that, for the overwhelming majority of observations, the disclosed amounts are not quantitatively material. This suggests that non-disclosure is likely due to immateriality. We next attempt to differentiate the choice to disclose across voluntary disclosure theory and legitimacy theory arguments. Our findings show that disclosing firms do not exhibit improved subsequent environmental performance relative to non-disclosing companies. Further, controlling for firm size and industry class, we find the choice to disclose is associated with worse environmental performance. Overall, our results suggest that companies use the disclosure of environmental capital spending as a strategic tool to address their exposures to political and regulatory concerns.

A Recurrent Neural-Network-Based Sensor and Actuator Fault Detection and Isolation for Nonlinear Systems With Application to the Satellite's Attitude Control Subsystem

Abstract: This paper presents a robust fault detection and isolation (FDI) scheme for a general class of nonlinear systems using a neural-network-based observer strategy. Both actuator and sensor faults are considered. The nonlinear system considered is subject to both state and sensor uncertainties and disturbances. Two recurrent neural networks are employed to identify general unknown actuator and sensor faults, respectively. The neural network weights are updated according to a modified backpropagation scheme. Unlike many previous methods developed in the literature, our proposed FDI scheme does not rely on availability of full state measurements. The stability of the overall FDI scheme in presence of unknown sensor and actuator faults as well as plant and sensor noise and uncertainties is shown by using the Lyapunov's direct method. The stability analysis developed requires no restrictive assumptions on the system and/or the FDI algorithm. Magnetorquer-type actuators and magnetometer-type sensors that are commonly employed in the attitude control subsystem (ACS) of low-Earth orbit (LEO) satellites for attitude determination and control are considered in our case studies. The effectiveness and capabilities of our proposed fault diagnosis strategy are demonstrated and validated through extensive simulation studies.

Adaptive Neural Control for a Class of Uncertain Nonlinear Systems in Pure-Feedback Form With Hysteresis Input

Abstract: In this paper, adaptive neural control is investigated for a class of unknown nonlinear systems in pure-feedback form with the generalized Prandtl-Ishlinskii hysteresis input. To deal with the nonaffine problem in face of the nonsmooth characteristics of hysteresis, the mean-value theorem is applied successively, first to the functions in the pure-feedback plant, and then to the hysteresis input function. Unknown uncertainties are compensated for using the function approximation capability of neural networks. The unknown virtual control directions are dealt with by Nussbaum functions. By utilizing Lyapunov synthesis, the closed-loop control system is proved to be semiglobally uniformly ultimately bounded, and the tracking error converges to a small neighborhood of zero. Simulation results are provided to illustrate the performance of the proposed approach.

Dual-tasking and gait in people with Mild Cognitive Impairment. The effect of working memory

Abstract: Cognition and mobility in older adults are closely associated and they decline together with aging. Studies evaluating associations between cognitive factors and gait performance in people with Mild Cognitive Impairment (MCI) are scarce. In this study, our aim was to determine whether specific cognitive factors have a more identifiable effect on gait velocity during dual-tasking in people with MCI. Fifty-five participants, mean age 77.7 (SD = 5.9), 45% women, with MCI were evaluated for global cognition, working memory, executive function, and attention. Gait Velocity (GV) was measured under a single-task condition (single GV) and under two dual-task conditions: 1) while counting backwards (counting GV), 2) while naming animals (verbal GV). Multivariable linear regression analysis was used to examine associations with an alpha-level of 0.05. Participants experienced a reduction in GV while engaging in dual-task challenges (p < 0.005). Low executive function and working memory performances were associated with slow single GV (p = 0.038), slow counting GV (p = 0.017), and slow verbal GV (p = 0.031). After adjustments, working memory was the only cognitive factor which remained significantly associated with a slow GV. In older adults with MCI, low working memory performance was associated with slow GV. Dual-task conditions showed the strongest associations with gait slowing. Our findings suggest that cortical control of gait is associated with decline in working memory in people with MCI.

Relating Structure to Function: Heschl's Gyrus and Acoustic Processing

Abstract: The way in which normal variations in human neuroanatomy relate to brain function remains largely uninvestigated. This study addresses the question by relating anatomical measurements of Heschl9s gyrus (HG), the structure containing human primary auditory cortex, to how this region processes temporal and spectral acoustic information. In this study, subjects9 right and left HG were identified and manually indicated on anatomical magnetic resonance imaging scans. Volumes of gray matter, white matter, and total gyrus were recorded, and asymmetry indices were calculated. Additionally, cortical auditory activity in response to noise stimuli varying orthogonally in temporal and spectral dimensions was assessed and related to the volumetric measurements. A high degree of anatomical variability was seen, consistent with other reports in the literature. The auditory cortical responses showed the expected leftward lateralization to varying rates of stimulus change and rightward lateralization of increasing spectral information. An explicit link between auditory structure and function is then established, in which anatomical variability of auditory cortex is shown to relate to individual differences in the way that cortex processes acoustic information. Specifically, larger volumes of left HG were associated with larger extents of rate-related cortex on the left, and larger volumes of right HG related to larger extents of spectral-related cortex on the right. This finding is discussed in relation to known microanatomical asymmetries of HG, including increased myelination of its fibers, and implications for language learning are considered.

Actuator Fault Detection and Isolation for a Network of Unmanned Vehicles

Abstract: This technical note investigates development, design and analysis of actuator fault detection and isolation (FDI) filters for a network of unmanned vehicles. It is shown that actuator fault signatures in a network of unmanned vehicles are dependent and the network can be considered as an over-actuated system. An isolability index mu is defined for a family of fault signatures and a new structured residual set is developed that is selectively capable of properly detecting and isolating mu multiple faults in linear systems with dependent fault signatures, such as over-actuated systems. Our proposed algorithm is then applied to the actuator FDI problem in a network of unmanned vehicles configured according to centralized, decentralized and semi-decentralized architectures. A comparative analysis in terms of the capabilities and limitations of these architectures is performed. Simulation results presented for the formation flight of multiple satellites demonstrate the effectiveness of our proposed FDI algorithm.

Varieties of Asian Capitalism: Toward an Institutional Theory of Asian Enterprise

Abstract: In this paper we respond to calls for an institution-based perspective on strategy. With its emphasis upon mimetic, coercive, and normative isomorphism, institutional theory has earned a deterministic reputation and seems an unlikely foundation on which to construct a theory of strategy. However, a second movement in institutional theory is emerging that gives greater emphasis to creativity and agency. We develop this approach by highlighting co-evolutionary processes that are shaping the varieties of capitalism (VoC) in Asia. To do so, we examine the extent to which the VoC model can be fruitfully applied in the Asian context. In the spirit of the second movement of institutional theory, we describe three processes in which firm strategy collectively and intentionally feeds back to shape institutions: (1) filling institutional voids, (2) retarding institutional innovation, and (3) deploying institutional escape. We outline the key contributions contained in the articles of this Special Issue and discuss a research agenda generated by the VoC perspective.

Privacy-Aware Attribute-Based Encryption with User Accountability

Abstract: As a new public key primitive, attribute-based encryption (ABE) is envisioned to be a promising tool for implementing fine-grained access control. To further address the concern of user access privacy, privacy-aware ABE schemes are being developed to achieve hidden access policy recently. For the purpose of secure access control, there is, however, still one critical functionality missing in the existing ABE schemes, which is user accountability. Currently, no ABE scheme can completely prevent the problem of illegal key sharing among users. In this paper, we tackle this problem by firstly proposing the notion of accountable, anonymous, and ciphertext-policy ABE (CP-A3BE, in short) and then giving out a concrete construction. We start by improving the state-of-the-art of anonymous CP-ABE to obtain shorter public parameters and ciphertext length. In the proposed CP-A3BE construction, user accountability can be achieved in black-box model by embedding additional user-specific information into the attribute private key issued to that user, while still maintaining hidden access policy. The proposed constructions are provably secure.

Sticking it all together: A critical assessment of the group cohesion–performance literature

Abstract: Although group cohesion is a widely studied construct in the group dynamics literature, there is a considerable lack of consistency and agreement regarding the construct. This paper reviews the current state of the cohesiveness literature. Cohesion is now generally defined as the group members’ inclinations to forge social bonds, resulting in the group sticking together and remaining united. Unfortunately, the large number of definitions and measures used by researchers has created a literature that is inconsistent and confusing. This review focuses on the considerable research on the cohesion–performance relationship. The general consensus of this research is that there is a generally positive association between cohesion and performance, but the theoretical and operational mechanisms creating this association are unclear. This lack of clarity may be due to the wide range of measures and assessments of cohesion and the cohesion–performance association. Two underlying contentious issues within this aspect of the literature are whether cohesion is unidimensional or multidimensional and the appropriate level of analysis required for measuring the construct. The resolution of these inconsistencies requires researchers to take a step back toward grounding the research in broader theoretical frameworks, to determine whether the cohesion–performance association has an underlying common cause, and to use longitudinal studies that use more sophisticated analytical models.