Concordia University Montreal
Recent publications
Analyzing the orientation of polymeric crystalline lamella at the surface of thin films can be challenging. Even though atomic force microscopy (AFM) is often sufficient for this analysis, there are cases when imaging is not sufficient to confidently determine lamellar orientation. Here, we used sum frequency generation (SFG) spectroscopy to analyze the lamellar orientation at the surface of semi-crystalline isotactic polystyrene (iPS) thin films. The SFG orientation analysis indicated that the iPS chains are oriented perpendicular to the substrate (flat-on lamellar orientation), which was confirmed by AFM. By analyzing the evolution of the SFG spectral features with the progress of crystallization, we demonstrated that the ratios of the SFG intensities of the phenyl ring resonances are a good indication of the surface crystallinity. Furthermore, we explored the challenges associated with SFG measurements of heterogeneous surfaces, which is commonly present in many semi-crystalline polymeric films. To the best of our knowledge, this is the first time that the surface lamellar orientation of semi-crystalline polymeric thin films was determined by SFG. Also, this work pioneers in reporting the surface conformation of semi-crystalline and amorphous iPS thin films by SFG and in linking the SFG intensity ratios to the progress of the crystallization and the surface crystallinity. This study demonstrates the potential applicability of SFG spectroscopy in the conformational analysis of polymeric crystalline structures at interfaces and opens the way to the investigation of more complex polymeric structures and crystalline arrangements, especially for the case of buried interfaces, where AFM imaging is not an option.
Indoor thermal comfort represents a key aspect of building design. The reference standards do not consider the thermal adaptability of the human body, and HVAC system control strategies are based on a steady-state assumption that returns an incorrect estimate of occupants’ thermal demand with a consequential misleading of the building energy consumption and of system sizing. To overcome these issues, a physiological thermal comfort model for the human body thermal behaviour evaluation is developed in MatLab environment for assessing the dynamic variation of the physiological parameters and for characterizing the occupants’ thermal sensation. Finally, the developed human body multi-node model is implemented in a building energy simulation tool (called DETECt 2.4) to perform three proposed strategies for the dynamic control of the building thermo-hygrometric parameters of the building and of the corresponding heating and cooling demands. These strategies provide a hourly regulation of relative humidity and air temperature by means of a two-step optimization that maximizes the thermal comfort of the occupants and minimizes energy consumption. To show the potentiality of the developed model, a suitable case study consisting of an office space is considered. Here, space heating and cooling demands obtained by applying the novel developed model are compared to those obtained through standard set-point values of air temperature and relative humidity (20°C, 45% for heating needs, and 26°C, 50% for cooling ones).
Background: There is limited understanding of associations between a combination of health behaviors (physical activity, sedentary/screen-time, diet) and cardiometabolic health risk factors, physical performance, and emotional health among young (<18) childhood cancer survivors (CCS). The aims of this research were to address this gap by 1) deriving health behavior adherence profiles among CCS, and 2) examining associations among demographic, diagnosis and/or treatment exposures, cardiometabolic, physical performance, and emotional functioning with health behavior profile membership. Methods: Participants included 397 CCS (≥5 years post-diagnosis; 10-17 years old) enrolled in the St. Jude Lifetime Cohort Study who completed physical health evaluations and questionnaires assessing health behaviors and psychological functioning. Latent profile analysis was used to derive profiles of health behavior adherence. Logistic regression and t-tests were used to examine mean-level differences and associations between profile membership with demographic, diagnosis, treatment exposures, cardiometabolic health, psychological functioning, and physical performance. Results: Two profiles emerged: inactive-unhealthy-diet ("IU") and active-sedentary-unhealthy-diet ("ASU") to guidelines. More participants in IU demonstrated higher resting heart rate (mean [M], 76.54; SD = 12.00) and lower motor proficiency scores (M = 34.73; SD = 29.15) compared to ASU (resting heart rate, M = 71.95, SD = 10.74; motor proficiency, M = 50.40, SD = 31.02). Conclusions: CCS exhibited low adherence to multiple health behavior guidelines, with adherence patterns differentially associated with cardiometabolic health (i.e., resting heart rate) and physical performance. However, robust protection against all health variables was not observed. Findings suggest interventions designed to improve health outcomes should target multiple health behaviors simultaneously. Plain language summary: Pediatric cancer survivors are at-risk for detrimental health outcomes associated with cancer and treatment. Engagement in healthy lifestyle behaviors serves to reduce health vulnerabilities among adult survivors but less is known about associations with lifestyle behaviors on young survivors. This study documents patterns of lifestyle behaviors among survivors of pediatric cancer, factors that increase susceptibility to nonadherence, and associations among lifestyle behaviors and health indicators.
Background: Gray's original Reinforcement Sensitivity Theory (RST) posits that an oversensitive behavioral inhibition system (BIS) may increase risk for negative-reinforcement-motivated drinking, given its role in anxiety. However, existing data provides mixed support for the BIS-alcohol use association. The inconsistent evidence is not surprising, as the revised RST predicts that the behavioral approach system (BAS) should moderate the effect of the BIS on alcohol use. A strong BAS is thought to bring attention to the negatively reinforcing effects of alcohol, leading to problem drinking among those with a strong BIS. While emerging results support this interaction, we still have much to learn about the mechanisms underlying this effect on alcohol use. Accordingly, we examined motives for alcohol use as mediators of the joint associations of the BIS and the BAS on drinking behaviors. Specifically, our central hypothesis was that individuals with a strong BIS and a strong BAS would endorse increased negative reinforcement motives for drinking (coping and conformity motives), which in turn would predict heavy drinking and alcohol problems. Method: Participants (N=346; 195 women) completed study measures as part of the baseline assessment for a larger study. Results: Overall, results partially supported the hypotheses. Mediated moderation analyses showed that the indirect effect of the BIS on alcohol problems, through coping and conformity motives, was strongest at high levels of the BAS. This effect was not supported for alcohol use. Conclusions: Our findings suggest that clinical interventions should target coping and conformity reasons for drinking among anxious, reward responsive, young adults.
Prior research suggests that gendered norms of appearance are particularly demanding in East Asian societies, including Taiwan. However, it remains unclear how the factor of temporality is related to women’s beautification. Relying on 62 in-depth interviews with Taiwanese women, we explore women’s mobilization of feminine appearance as an important aspirational strategy to gain various advantages and some women’s resistance to those bodily norms in Taiwan’s neoliberal context. The findings reveal that, in both cases, women’s attitude toward the future is determinant. The apprehension of appearance in the future could be illustrated by women’s concern for aging well, their meticulous preparation for maternity, and mothers’ investment in their daughters’ beauty practices. Paradoxically neoliberalism’s future-oriented temporality could result in a resistant attitude toward female beauty, since endless bodily work might lead to a withdrawal from the constant investment in female appearance.
Autobiographical memory (AM) involves a rich phenomenological re-experiencing of a spatio-temporal event from the past, which is challenging to objectively quantify. The Autobiographical Interview (AI; Levine et al. Psychology and Aging, 17(4), 677-689, 2002) is a manualized performance-based assessment designed to quantify episodic (internal) and semantic (external) features of recalled and verbally conveyed prior experiences. The AI has been widely adopted, yet has not undergone a comprehensive psychometric validation. We investigated the reliability, validity, association to individual differences measures, and factor structure in healthy younger and older adults (N = 352). Evidence for the AI's reliability was strong: the subjective scoring protocol showed high inter-rater reliability and previously identified age effects were replicated. Internal consistency across timepoints was robust, suggesting stability in recollection. Central to our validation, internal AI scores were positively correlated with standard, performance-based measures of episodic memory, demonstrating convergent validity. The two-factor structure for the AI was not well supported by confirmatory factor analysis. Adjusting internal and external detail scores for the number of words spoken (detail density) improved trait estimation of AM performance. Overall, the AI demonstrated sound psychometric properties for inquiry into the qualities of autobiographical remembering.
Liquid crystal elastomer is a type of soft material with unique physical and chemical properties that offer a variety of possibilities in the growing field of soft robot actuators. This type of material is able to exhibit large, revertible deformation under various external stimuli, including heat, electric or magnetic fields, light, etc., which may lead to a wide range of different applications such as bio-sensors, artificial muscles, optical devices, solar cell plants, etc. With these possibilities, it is important to establish modeling and control strategies for liquid crystal elastomer-based actuators, to obtain the accurate prediction and description of its physical dynamics. However, so far, existing studies on this type of the actuators mainly focus on material properties and fabrication, the state of art on the modeling and control of such actuators is still preliminary. To gain a better understanding on current studies of the topic from the control perspective, this review provides a brief collection on recent studies on the modeling and control of the liquid crystal elastomer-based soft robot actuator. The review will introduce the deformation mechanism of the actuator, as well as basic concepts. Existing studies on the modeling and control for the liquid crystal elastomer-based actuator will be organized and introduced to provide an overview in this field as well as future insights.
This paper proposes the concept of mapping-ofrenda, which envisions mapping as a form of mourning and remembering while living in the context of migration. Inspired by the traditional Mexican ofrenda, the mapping-ofrenda aims to collect, curate, and represent posthumous memories. It can be produced collaboratively or individually, built with physical or digital maps, shared with other people, or kept private, and be dedicated to a single deceased or to an entire community. Through the process of co-designing two online ofrenda-maps with two Latina-American women living in Montreal (Canada) we identified some of the potential of mapping-ofrenda, including its capacity to stimulate our memories and remember stories on the verge of disappearing, to ground them to places, and to share them with people that might live far away. Mapping-ofrenda can also be a way of making visible the global geography of migration through highly intimate memories and acknowledging both the very personal and the highly universal need to remember and grieve. Finally, the main value of mapping-ofrenda in the context of migration, may be its capacity to reactivate and strengthen existing links and connections between people that are still alive but that may live far away.
The present study compared the learning and experiences of Kenyan teachers randomly assigned to either an online or a blended 12-week intensive teacher professional development program (TPD). The TPD addressed the fundamentals of early literacy development as well as how to use early literacy software to support students learning. TPD outcomes were assessed through surveys, course performance and discussion elements. Teachers demonstrated pre- to post-test gains in domain knowledge, lesson plan construction and comfort teaching early literacy skills. Few differences were observed between the online versus blended formats. However, teachers endorsed a blended instructional format over online-only or in-person formats. Challenges regarding resources and infrastructure were identified as barriers to technology integration within the classroom. Some cultural challenges were identified as potential barriers for young learners using software developed in Western countries. Overall, both online and blended formats appear to be effective TPD delivery systems for Kenyan teachers, however, findings highlighted challenges that need to be addressed to optimize learning when using technology. Future research recommendations include broadening the teacher sample to assess potential differences due to regionalism, associated differences in access to resources, and further examination of teaching experience on learning in the two types of online formats.
Grazing Incidence X-ray Diffraction (GIXD) has been established as a powerful tool for the structural characterization of thin films. However, indexing of the experimentally observed diffraction peaks without prior knowledge of the involved crystal lattices has turned out as a challenging task. During the last years a series of works were published which introduce indexing methods for different methods of GIXD experiments. Static GIXD measurements are performed at fixed sample positions for thin films with preferred orientation of the crystallites relative to the substrate surface but without any in-plane order. Rotated GIXD measurements use rotation of the thin film sample about the substrate normal and collect for each rotation angle a single detector image. This method is used for crystals with azimuthal alignments within the thin film. A comprehensive mathematical framework is developed which provides the assignment of Laue indices to the individual diffraction peaks. The algorithms are even reduced from the three-dimensional case to two-dimensional representation of the experimental results. Despite the fact that GIXD experiments provide only a limited number of diffraction peaks, indexing became possible even for thin film crystals with low symmetry, different preferred orientations and multiple azimuthal alignments.
Many parents express concerns for their children’s multilingual development, yet little is known about the nature and strength of these concerns – especially among parents in multilingual societies. This pre-registered, questionnaire-based study addresses this gap by examining the concerns of 821 Quebec-based parents raising infants and toddlers aged 0–4 years with multiple languages in the home. Factor analysis of parents’ Likert-scale responses revealed that parents had (1) concerns regarding the effect of children’s multilingualism on their cognition, and (2) concerns regarding children’s exposure to and attainment of fluency in their languages. Concern strength was moderate to weak, and cognition concerns were weaker than exposure-fluency concerns. Transmission of a heritage language, transmission of three or more languages, presence of developmental issues, and less positive parental attitudes towards childhood multilingualism were associated with stronger concerns. These findings have both theoretical and practical implications: they advance our understanding of parental concerns and facilitate the development of support for multilingual families.
Refugia-based conservation strategies offer long-term effectiveness and minimize uncertainty on strategies for climate change adaptation. Here, we use distribution modelling to identify climate change refugia for 617 terrestrial mammals and quantify the role of protected areas in safeguarding these zones across South America. Moist tropical forests located in high-elevation areas with complex topography concentrated the highest local diversity of species refugia, although regionally important refugia centers were also found elsewhere. Andean Amazon forests were revealed as "Anthropocene museums", hosting climate change refugia for more than half the continental species' pool and up to 87 species locally (17×17 km2 grid cell). The highland zones of the Southern Atlantic Forest also included megadiverse refugia, safeguarding up to 76 species per cell. Almost half of the species that may find refugia in the Atlantic Forest will do so in a single region - the Serra do Mar and Serra do Espinhaço. Most of the refugia highlighted here, however, are not covered by protected areas, which may shelter less than 6% of the total area of climate change refugia, leaving 129 to 237 species with no refugia inside the territorial limits of protected areas of any kind. Those results reveal a dismal scenario on the level of refugia protection in some of the most biodiverse regions of the world. Nonetheless, because refugia areas tend to be located in high-elevation, topographically complex and remote areas, with lower economic pressure, formally protecting them may require a comparatively modest investment. This article is protected by copyright. All rights reserved.
In this paper, we investigate the meanings and experiences of active leisure among first time mothers. The connection of first time mothers’ experiences to broader concepts such as intensive mothering, social policy, and neoliberalism are also examined within the context of their well-being. Using narrative analysis, 27 interviews were conducted with nine first time mothers participating in three in-person interviews over three months. Five stories were constructed that call attention to the importance of social relationships in creating opportunities for active leisure participation as well as confronting challenges related to the first time mothers’ recovering post-partum bodies. The findings from this study are important to consider for prospective first time mothers and those who wish to support them (e.g. academics, policymakers, sport, leisure, health and social service professionals) as the transition to motherhood may be marked with social isolation, depression, and a need to be connected to others.
On-chip optical isolation is currently one of the main challenges of photonic integrated circuits. Thus, there is a need for materials that exhibit both Faraday rotation and the ability to be scaled down to match the size constraints of the chip. In this contribution, we assess the potential for SnO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {SnO}_{2}$$\end{document}@Au core-shell nanoparticles for such materials, through simulation of the Faraday rotation and absorption in comparison to core-shell nanoparticles synthesized by reverse micelle templating. The simulation accurately accounts for the enhanced magneto-optical properties of the tin oxide core due to the surface plasmon resonance effects of the gold shell, which results in a sharper and larger peak in the Verdet constant of core-shell nanoparticles with thicker gold shells. We produced core-shell nanoparticles, examined their absorption and magnetic behaviour and incorporated them into a waveguide setup to assess their feasibility as isolator materials. Though further optimization of the structures are needed, this work shows the potential of such particles to be easily produced and incorporated into cladding materials for optical isolation.
This paper introduces a flexible risk decomposition method for life insurance contracts embedding several risk factors. Hedging can be naturally embedded in the framework. Although the method is applied to variable annuities in this work, it is also applicable in general to other insurance or financial contracts. The approach relies on applying an allocation principle to components of a Shapley decomposition of the gain and loss. The implementation of the allocation method requires the use of a stochastic on stochastic algorithm involving nested simulations. Numerical examples studying the relative impact of equity, interest rate and mortality risk for guaranteed minimal maturity benefit (GMMB) policies conclude our analysis.
This paper investigates the downlink (DL) performance of cell-free (CF) massive multiple-input multiple-output (mMIMO) systems under a wireless mMIMO-based fronthaul network operation. Particularly, we consider multiple edge-cloud processors (ECP)s serving access points (AP)s using one of three possible fronthaul network operations, namely, microwave, millimeter wave (mmWave), or hybrid microwave/mmWave. Under each fronthaul network operation, we analyze the achievable DL data rates for two different microwave-based operations of the access link (APs-users), namely, distributed and centralized operations, while assuming APs with/without decoding capabilities. In the distributed operation, APs are responsible for performing both channel estimation and DL data precoding tasks, whereas ECPs are the responsible entities for carrying out such tasks in the centralized counterpart. Our results show that the integration between the centralized access link operation and the hybrid-based fronthaul network provides the highest DL data rates when APs are empowered with decoding capabilities. However, integrating the distributed access link operation with the microwave-based fronthaul network achieves ultimate performance when APs are not supported with decoding capabilities. Interestingly, we reveal that APs with low fronthaul capacities dominantly control the preferred network configuration in-terms of the densities and the number of deployed antennas for both APs and ECPs.
In this paper, we investigated whether Canadian preschoolers prefer to learn from a competent robot over an incompetent human using the classic trust paradigm. An adapted Naive Biology task was also administered to assess children’s perception of robots. In Study 1, 3-year-olds and 5-year-olds were presented with two informants; A social, humanoid robot (Nao) who labeled familiar objects correctly, while a human informant labeled them incorrectly. Both informants then labeled unfamiliar objects with novel labels. It was found that 3-year-old children equally endorsed the labels provided by the robot and the human, but 5-year-old children learned significantly more from the competent robot. Interestingly, 5-year-olds endorsed Nao’s labels even though they accurately categorized the robot as having mechanical insides. In contrast, 3-year-old children associated Nao with biological or mechanical insides equally. In Study 2, new samples of 3-year-olds and 5-year-olds were tested to determine whether the human-like appearance of the robot informant impacted children’s trust judgments. The procedure was identical to that of Study 1, except that a non-humanoid robot, Cozmo, replaced Nao. It was found that 3-year-old children still trusted the robot and the human equally and that 5-year-olds preferred to learn new labels from the robot, suggesting that the robot’s morphology does not play a key role in their selective trust strategies. It is concluded that by 5 years of age, preschoolers show a robust sensitivity to epistemic characteristics (e.g., competency), but that younger children’s decisions are equally driven by the animacy of the informant.
Wall cooling panels are typically a kind of electric arc furnace equipment that has precisely influence on different aspects of the steelmaking process. This investigation employs a CFD method to evaluate the thermal performance of water cooling panels in real operating conditions to validate the numerical method followed by replacing cooling water with Al2O3/Water nanofluid coolant. The results are revealed that the high rate of receiving heat flux and generated vortexes with low-velocity cores lead to hot spots inducing on bends and elbows. In the operating flow rate, the maximum temperature of the hot-side wall decrease by 14.4% through increasing the nanoparticle concentration up to 5%, where the difference between maximum temperature and average temperature on the hot-side decrease to 12 degrees. According to the results, use of nanofluid coolant is a promising method to fade the hot spots out on the hot-side and gifting a lower and smoother temperature distribution on the panel walls of thereby prolonging the usage period of panels.
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9,972 members
Christopher J Steele
  • Department of Psychology
Otto Schwelb
  • Department of Electrical and Computer Engineering
Simona Badilescu
  • Department of Mechanical and Industrial Engineering
Steven Appelbaum
  • John Molson School of Business
Marta A. Kersten-Oertel
  • Department of Computer Science and Software Engineering
Montréal, Canada