Showing papers by "Concordia University published in 2015"

SoK: Research Perspectives and Challenges for Bitcoin and Cryptocurrencies

Abstract: Bit coin has emerged as the most successful cryptographic currency in history. Within two years of its quiet launch in 2009, Bit coin grew to comprise billions of dollars of economic value despite only cursory analysis of the system's design. Since then a growing literature has identified hidden-but-important properties of the system, discovered attacks, proposed promising alternatives, and singled out difficult future challenges. Meanwhile a large and vibrant open-source community has proposed and deployed numerous modifications and extensions. We provide the first systematic exposition Bit coin and the many related crypto currencies or 'altcoins.' Drawing from a scattered body of knowledge, we identify three key components of Bit coin's design that can be decoupled. This enables a more insightful analysis of Bit coin's properties and future stability. We map the design space for numerous proposed modifications, providing comparative analyses for alternative consensus mechanisms, currency allocation mechanisms, computational puzzles, and key management tools. We survey anonymity issues in Bit coin and provide an evaluation framework for analyzing a variety of privacy-enhancing proposals. Finally we provide new insights on what we term disinter mediation protocols, which absolve the need for trusted intermediaries in an interesting set of applications. We identify three general disinter mediation strategies and provide a detailed comparison.

Strategies for Teaching Students to Think Critically A Meta-Analysis

Abstract: Critical thinking (CT) is purposeful, self-regulatory judgment that results in interpretation, analysis, evaluation, and inference, as well as explanations of the considerations on which that judgment is based. This article summarizes the available empirical evidence on the impact of instruction on the development and enhancement of critical thinking skills and dispositions and student achievement. The review includes 341 effects sizes drawn from quasi- or true-experimental studies that used standardized measures of CT as outcome variables. The weighted random effects mean effect size (g+) was 0.30 (p < .001). The collection was heterogeneous (p < .001). Results demonstrate that there are effective strategies for teaching CT skills, both generic and content specific, and CT dispositions, at all educational levels and across all disciplinary areas. Notably, the opportunity for dialogue, the exposure of students to authentic or situated problems and examples, and mentoring had positive effects on CT skills.

Image fusion based on pixel significance using cross bilateral filter

Abstract: Like bilateral filter (BF), cross bilateral filter (CBF) considers both gray-level similarities and geometric closeness of the neighboring pixels without smoothing edges, but it uses one image for finding the kernel and other to filter, and vice versa. In this paper, it is proposed to fuse source images by weighted average using the weights computed from the detail images that are extracted from the source images using CBF. The performance of the proposed method has been verified on several pairs of multisensor and multifocus images and compared with the existing methods visually and quantitatively. It is found that, none of the methods have shown consistence performance for all the performance metrics. But as compared to them, the proposed method has shown good performance in most of the cases. Further, the visual quality of the fused image by the proposed method is superior to other methods.

Industrial Electronics for Electric Transportation: Current State-of-the-Art and Future Challenges

Abstract: This paper presents the current research trends and future issues for industrial electronics related to transportation electrification. Specific emphasis is placed on electric and plug-in hybrid electric vehicles (EVs/PHEVs) and their critical drivetrain components. The paper deals with industry related EV energy storage system issues, EV charging issues, as well as power electronics and traction motor drives issues. The importance of battery cell voltage equalization for series-connected lithium-ion (Li-ion) batteries for extended life time is presented. Furthermore, a comprehensive overview of EV/PHEV battery charger classification, standards, and requirements is presented. Several conventional EV/PHEV front-end ac/dc charger converter topologies as well as isolated DC/DC topologies are reviewed. Finally, this paper reviews various EV propulsion system architectures and efficient bidirectional DC/DC converter topologies. Novel DC/AC inverter modulation techniques for EVs are also presented. The architectures are based on the battery voltage, capacity, and driving range.

What Do Mobile App Users Complain About

Abstract: Mobile-app quality is becoming an increasingly important issue. These apps are generally delivered through app stores that let users post reviews. These reviews provide a rich data source you can leverage to understand user-reported issues. Researchers qualitatively studied 6,390 low-rated user reviews for 20 free-to-download iOS apps. They uncovered 12 types of user complaints. The most frequent complaints were functional errors, feature requests, and app crashes. Complaints about privacy and ethical issues and hidden app costs most negatively affected ratings. In 11 percent of the reviews, users attributed their complaints to a recent app update. This study provides insight into the user-reported issues of iOS apps, along with their frequency and impact, which can help developers better prioritize their limited quality assurance resources.

An enzyme-coupled biosensor enables ( S )-reticuline production in yeast from glucose

Abstract: The biosynthesis of benzylisoquinoline alkaloids such as morphine requires tyrosine oxidases, which are prone to overoxidation. A colorimetric readout that co-opts betaxanthin enzymes now enables discovery of an improved oxidase that, with other enzymes, makes reticuline in yeast.

Photon upconversion nanomaterials

Abstract: Photon upconversion through the use of lanthanide-doped materials has been the focus of a growing body of research in the fields of materials chemistry and physics for more than 50 years. The attraction of this field has been the ability to generate photons at shorter wavelengths than the excitation wavelength after laser stimulation. Despite its potential utility for a number of applications, photon upconversion has been primarily investigated in bulk glasses or crystalline materials. That situation dramatically changed in the mid-2000s, with the widespread research in the development of upconversion nanomaterials. As a unique class of optical materials, upconversion nanomaterials exhibit useful applications spanning from lighting to volumetric 3D displays to photovoltaics. Particularly, nanosized upconversion nanocrystals have proven valuable as luminescent labels for chemical and biological sensing with marked improvements in the sensitivity and versatility of the sensors. Recent advances in the field of upconversion nanomaterials have motivated us to initiate a thematic issue focusing on fundamental principles, synthetic strategies, materials characterization, broad applications, and a Department of Chemistry, National University of Singapore, Singapore 117543, Singapore. E-mail: chmlx@nus.edu.sg b Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore 117602, Singapore c Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, Peking University, Beijing 100871, China. E-mail: yan@pku.edu.cn d Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, Montreal, Quebec, H4B 1R6, Canada. E-mail: john.capobianco@concordia.ca † Part of the photon upconversion nanomaterials themed issue.

Empathy and involvement in bullying in children and adolescents: a systematic review

Abstract: Based on the premise that bullies are deficient in empathy or even lack it completely, bullying prevention and intervention programs often include empathy training. These programs are not always as effective as they aim to be, which may be caused by a failure to acknowledge the multidimensional nature of empathy as well as its complex association with involvement in bullying. To provide a clear overview of the research on the association between empathy and involvement in bullying, this article systematically reviews 40 studies on the association of cognitive empathy (24 studies) and affective empathy (38 studies) with four categories of involvement in bullying: bullying, victimization, defending, and bystanding. The results showed that bullying was negatively associated with cognitive and-in particular-affective empathy. Victimization was negatively associated with cognitive empathy but not with affective empathy. Defending was consistently positively associated with both types of empathy. Contradictory findings were observed in bystanding, with studies reporting both negative and positive associations with cognitive empathy, and studies reporting negative and no associations with affective empathy. Together, the findings stress the importance of the distinction between cognitive and affective empathy in involvement in bullying and suggest different intervention strategies for the four types of involvement in bullying.

Relay-Selection Improves the Security-Reliability Trade-Off in Cognitive Radio Systems

Abstract: We consider a cognitive radio (CR) network consisting of a secondary transmitter (ST), a secondary destination (SD) and multiple secondary relays (SRs) in the presence of an eavesdropper, where the ST transmits to the SD with the assistance of SRs, while the eavesdropper attempts to intercept the secondary transmission. We rely on careful relay selection for protecting the ST-SD transmission against the eavesdropper with the aid of both single-relay and multi-relay selection. To be specific, only the “best” SR is chosen in the single-relay selection for assisting the secondary transmission, whereas the multi-relay selection invokes multiple SRs for simultaneously forwarding the ST's transmission to the SD. We analyze both the intercept probability and outage probability of the proposed single-relay and multi-relay selection schemes for the secondary transmission relying on realistic spectrum sensing. We also evaluate the performance of classic direct transmission and artificial noise based methods for the purpose of comparison with the proposed relay selection schemes. It is shown that as the intercept probability requirement is relaxed, the outage performance of the direct transmission, the artificial noise based and the relay selection schemes improves, and vice versa. This implies a trade-off between the security and reliability of the secondary transmission in the presence of eavesdropping attacks, which is referred to as the security-reliability trade-off (SRT). Furthermore, we demonstrate that the SRTs of the single-relay and multi-relay selection schemes are generally better than that of classic direct transmission, explicitly demonstrating the advantage of the proposed relay selection in terms of protecting the secondary transmissions against eavesdropping attacks. Moreover, as the number of SRs increases, the SRTs of the proposed single-relay and multi-relay selection approaches significantly improve. Finally, our numerical results show that as expected, the multi-relay selection scheme achieves a better SRT performance than the single-relay selection.

The Mediation Myth

Abstract: The mediation myth is the false belief that mediation is actually estimated in the typical mediation analysis. This myth is based on a trifecta of shortcomings: (1) the typical mediation study reli...

What Do We Know About Private Family Firms? A Meta-Analytical Review

Abstract: The universe of family firms is heterogeneous, and findings gleaned from publicly listed firms may not apply to the ubiquitous, but less frequently studied, privately held family firm (PFF). As PFFs are insulated from capital market pressures, owner-managers have greater latitude in setting strategic goals, which may result in different strategic choices and performance outcomes. By employing meta-analytical techniques on 48 studies conducted in nine countries, we synthesize prior PFF research. We show that PFFs prefer more conservative strategies, but contrary to received wisdom, this risk aversion does not hurt their performance. We conclude with an agenda for future research.

A Manifesto for Abundant Futures

Abstract: The concept of the Anthropocene is creating new openings around the question of how humans ought to intervene in the environment. In this article, we address one arena in which the Anthropocene is ...

Communication and trust are key: Unlocking the relationship between leadership and team performance and creativity

Abstract: Considerable theoretical and empirical work has identified a relationship between transformational leadership and team performance and creativity. The mechanisms underlying this link, however, are not well understood. To identify the intervening processes inherent in this relationship, we experimentally manipulated the leadership style assigned to 44 teams taking part in a resource-maximization task. Teams were exposed either to a leader using inspirational motivation, intellectual stimulation, or a control condition. Our findings reveal important differences between leadership styles in communication and team outcomes (objective task performance and creativity). These results suggest that different dimensions of transformational leadership should be emphasized depending on the outcome sought. In addition, our results provide evidence for a sequential mediation model where leadership influences team outcomes through overall team communication and trust in teammates. This study suggests mechanisms by which transformational leaders may impact team outcomes, which has implications for team building and leadership training.

Cognitive plasticity in older adults: effects of cognitive training and physical exercise

Abstract: Cognitive training, physical activity, and exercise have often been reported to improve cognitive performance in older adults. This paper reviews some seminal and recent studies using these approaches to improve cognition and physical functioning in healthy older adults and in patients suffering from non-neurological chronic medical conditions. Results from cognitive training studies suggest that despite performance improvement in trained tasks, transfer effects appeared very limited. Surprisingly though, computerized dual-task training has been shown to improve balance and postural control in tests of physical functioning, suggesting that broad transfer can sometimes be observed. Physical exercise intervention studies generally found significant and large improvements in physical capacity, in some cognitive domains, and in quality of life. The benefits seem to be equivalent between frail and nonfrail participants. Overall, results reviewed here support the notion that cognitive plasticity for attentional control, as induced by cognitive training or physical activity and exercise, is preserved in late adulthood. Moreover, results of studies with patients at risk of cognitive decline also suggest that cognitive training and exercise interventions are promising nonpharmaceutical tools to help improve cognition in older at-risk individuals.

The use of the Godin-Shephard Leisure-Time Physical Activity Questionnaire in oncology research: a systematic review

Abstract: The Godin-Shephard Leisure-Time Physical Activity Questionnaire (GSLTPAQ) is one of the most often used questionnaires in oncology research, yet modifications to the scale are done with little evidence of psychometric testing. This study aimed to (i) document the frequency of use of the questionnaire for ranking (i.e., level of activity) and classification (i.e., active versus insufficiently active) purposes, (ii) summarize how the GSLTPAQ is used in terms of item content and scoring, and (iii) evaluate the extent to which validity evidence supports the use of the scale among cancer survivors. A systematic review was conducted with evidence drawn from English-written articles published between January 1st 1985 (year the GSLTPAQ was published) and December 31, 2014. A search of six databases, a scan of reference list of included articles, and a cited reference search identified articles that reported using the GSLTPAQ among cancer survivors. A total of 212 articles were retrieved. The GSLTPAQ was used for classifying cancer survivors into active and insufficiently active categories in 51 % of the articles. Moreover, a modified version of the questionnaire was used in 81 % of the research studies. Three studies reported validity evidence based on the relationship between the scores on the GSLTPAQ (i.e., leisure score index, LSI) and accelerometer or pedometer-derived activity data. Validity evidence supporting the use of the GSLTPAQ for assessing changes in LSI was computed from six randomized trials. The use of the GSLTPAQ for classification purpose in oncology research is common. Standardization in the use and interpretation of the GSLTPAQ in oncology research is warranted. Although limited, there is support for using the original form of the GSLTPAQ and interpreting the LSI for ranking cancer survivors from the lowest to highest levels of leisure-time physical activity.

Seasonal thermal energy storage with heat pumps and low temperatures in building projects—A comparative review

Abstract: Application of seasonal thermal energy storage with heat pumps for heating and cooling buildings has received much consideration in recent decades, as it can help to cover gaps between energy avail ...

"The sum of all human knowledge": A systematic review of scholarly research on the content of Wikipedia

Abstract: Wikipedia might possibly be the best-developed attempt thus far of the enduring quest to gather all human knowledge in one place. Its accomplishments in this regard have made it an irresistible point of inquiry for researchers from various fields of knowledge. A decade of research has thrown light on many aspects of the Wikipedia community, its processes, and content. However, due to the variety of the fields inquiring about Wikipedia and the limited synthesis of the extensive research, there is little consensus on many aspects of Wikipedia’s content as an encyclopedic collection of human knowledge. This study addresses the issue by systematically reviewing 110 peer-reviewed publications on Wikipedia content, summarizing the current findings, and highlighting the major research trends. Two major streams of research are identified: the quality of Wikipedia content (including comprehensiveness, currency, readability and reliability) and the size of Wikipedia. Moreover, we present the key research trends in terms of the domains of inquiry, research design, data source, and data gathering methods. This review synthesizes scholarly understanding of Wikipedia content and paves the way for future studies.

Fuzzy Approximation-Based Adaptive Backstepping Control of an Exoskeleton for Human Upper Limbs

Abstract: This paper presents fuzzy approximation-based adaptive backstepping control of an exoskeleton for human upper limbs to provide forearm movement assistance so that a human forearm can track any continuous desired trajectory (or constant setpoint) in the presence of parametric/functional uncertainties, unmodeled dynamics, actuator dynamics, and/or disturbances from environments. Given the desired trajectories of human forearm positions, in the developed control, adaptive fuzzy approximators are used to estimate the dynamical uncertainties of the human–robot system, and an iterative learning scheme is utilized to compensate for unknown time-varying periodic disturbances. With the synthesis of the backstepping, iterative learning, and Lyapunov function approaches, the developed controller does not require exact knowledge of the exoskeleton model, and the close-loop system can be proven to be semiglobally uniformly bounded. Three comparison experiments are conducted to illustrate the effectiveness of the proposed control scheme by tracking periodic/repeated trajectories.

UAV-based forest fire detection and tracking using image processing techniques

Abstract: In this paper, an unmanned aerial vehicle (UAV) based forest fire detection and tracking method is proposed. Firstly, a brief illustration of UAV-based forest fire detection and tracking system is presented. Then, a set of forest fire detection and tracking algorithms are developed including median filtering, color space conversion, Otsu threshold segmentation, morphological operations, and blob counter. The basic idea of the proposed method is to adopt the channel “a” in Lab color model to extract fire-pixels by making use of chromatic features of fire. Numerous experimental validations are carried out, and the experimental results show that the proposed methodology can effectively extract the fire pixels and track the fire zone.

On the Psychology of Scarcity: When Reminders of Resource Scarcity Promote Selfish (and Generous) Behavior

Abstract: Consumers often encounter reminders of resource scarcity. However, relatively little is known about the psychological processes that such reminders instantiate. In this article, we posit that reminders of resource scarcity activate a competitive orientation, which guides consumers’ decision making towards advancing their own welfare. Further, we reveal that this tendency can manifest in behaviors that appear selfish, but also in behaviors that appear generous, in conditions where generosity allows for personal gains. The current research thus offers a more nuanced understanding of why resource scarcity may promote behaviors that appear either selfish or generous in different contexts, and provides one way to reconcile seemingly conflicting prior findings.

Using Listener Judgments to Investigate Linguistic Influences on L2 Comprehensibility and Accentedness: A Validation and Generalization Study

Abstract: The current study investigated linguistic influences on comprehensibility (ease of understanding) and accentedness (linguistic nativelikeness) in second language (L2) learners’ extemporaneous speech. Target materials included picture narratives from 40 native French speakers of English from different proficiency levels. The narratives were subsequently rated by 20 native speakers with or without linguistic and pedagogical experience for comprehensibility, accentedness, and 11 linguistic variables spanning the domains of phonology, lexis, grammar, and discourse structure. Results showed that comprehensibility was associated with several linguistic variables (vowel/consonant errors, word stress, fluency, lexis, grammar), whereas accentedness was chiefly linked to pronunciation (vowel/consonant errors, word stress). Native-speaking listeners thus appear to pay particular attention to pronunciation, rather than lexis and grammar, to evaluate nativelikeness but tend to consider various sources of linguistic information in L2 speech in judging comprehensibility. The use of listener ratings (perceptual measures) in evaluating linguistic aspects of learner speech and their implications for language assessment and pedagogy are discussed.

What Are Priorities for Deprescribing for Elderly Patients? Capturing the Voice of Practitioners: A Modified Delphi Process

Abstract: Polypharmacy and inappropriate medication use among older adults contribute to adverse drug reactions, falls, cognitive impairment, noncompliance, hospitalization and mortality. While deprescribing - tapering, reducing or stopping a medication - is feasible and relatively safe, clinicians find it difficult to carry out. Deprescribing guidelines would facilitate this process. The aim of this paper is to identify and prioritize medication classes where evidence-based deprescribing guidelines would be of benefit to clinicians. A modified Delphi approach included a literature review to identify potentially inappropriate medications for the elderly, an expert panel to develop survey content and three survey rounds to seek consensus on priorities. Panel participants included three pharmacists, two family physicians and one social scientist. Sixty-five Canadian geriatrics experts (36 pharmacists, 19 physicians and 10 nurse practitioners) participated in the survey. Twenty-nine drugs/drug classes were included in the first survey with 14 reaching the required (≥ 70%) level of consensus, and 2 new drug classes added from qualitative comments. Fifty-three participants completed round two, and 47 participants completed round three. The final five priorities were benzodiazepines, atypical antipsychotics, statins, tricyclic antidepressants, and proton pump inhibitors; nine other drug classes were also identified as being in need of evidence-based deprescribing guidelines. The Delphi consensus process identified five priority drug classes for which expert clinicians felt guidance is needed for deprescribing. The classes of drugs that emerged strongly from the rankings dealt with mental health, cardiovascular, gastroenterological, and neurological conditions. The results suggest that deprescribing and overtreatment occurs through the full spectrum of primary care, and that evidence-based deprescribing guidelines are a priority in the care of the elderly.

The effect of brand design on brand gender perceptions and brand preference

Abstract: Purpose – This research aims to examine the impact of brand design elements (logo shape, brand name, type font and color) on brand masculinity and femininity perceptions, consumer preferences and brand equity. Design/methodology/approach – This research empirically tests the relation between brand design elements, brand masculinity and femininity and brand preferences/equity in four studies involving fictitious and real brands. Findings – Brand design elements consistently influenced brand masculinity and femininity perceptions. These, in turn, significantly related to consumer preferences and brand equity. Brand masculinity and femininity perceptions successfully predicted brand equity above and beyond other brand personality dimensions. Research limitations/implications – Although this research used a wide range of brand design elements, the interactive effects of various design elements warrant further research. Practical implications – This research demonstrates how markers of masculinity and feminini...

Found Poems, Member Checking and Crises of Representation

Abstract: In order to establish veracity, qualitative researchers frequently rely on member checks to insure credibility by giving participants opportunities to correct errors, challenge interpretations and assess results; however, member checks are not without drawbacks. This paper describes an innovative approach to conducting member checks. Six members of a learning organization participated in two group interviews to examine the use of poetry as a method to promote individual and organizational learning. Several weeks later, participants received a copy of their transcripts and were asked to create a “found poem” to reflect their thoughts and feelings about using poetry as a learning tool. There was resonance between the interview themes produced by traditional open coding methods and those using participant-created found poems. However, the found poems added an emotional depth and connection that was missing from the traditional approach of coding qualitative data. This suggests that participant-created found poems can provide an agentic alternative to the usual method of member checking and also expand the notions of aesthetic approaches within qualitative research.