Wilfrid Laurier University
  • Waterloo, Ontario, Canada
Recent publications
Background Most North American temperate forests are plantation or regrowth forests, which are actively managed. These forests are in different stages of their growth cycles and their ability to sequester atmospheric carbon is affected by extreme weather events. In this study, the impact of heat and drought events on carbon sequestration in an age-sequence (80, 45, and 17 years as of 2019) of eastern white pine ( Pinus strobus L.) forests in southern Ontario, Canada was examined using eddy covariance flux measurements from 2003 to 2019. Results Over the 17-year study period, the mean annual values of net ecosystem productivity (NEP) were 180 ± 96, 538 ± 177 and 64 ± 165 g C m –2 yr –1 in the 80-, 45- and 17-year-old stands, respectively, with the highest annual carbon sequestration rate observed in the 45-year-old stand. We found that air temperature (Ta) was the dominant control on NEP in all three different-aged stands and drought, which was a limiting factor for both gross ecosystem productivity (GEP) and ecosystems respiration (RE), had a smaller impact on NEP. However, the simultaneous occurrence of heat and drought events during the early growing seasons or over the consecutive years had a significant negative impact on annual NEP in all three forests. We observed a similar trend of NEP decline in all three stands over three consecutive years that experienced extreme weather events, with 2016 being a hot and dry, 2017 being a dry, and 2018 being a hot year. The youngest stand became a net source of carbon for all three of these years and the oldest stand became a small source of carbon for the first time in 2018 since observations started in 2003. However, in 2019, all three stands reverted to annual net carbon sinks. Conclusions Our study results indicate that the timing, frequency and concurrent or consecutive occurrence of extreme weather events may have significant implications for carbon sequestration in temperate conifer forests in Eastern North America. This study is one of few globally available to provide long-term observational data on carbon exchanges in different-aged temperate plantation forests. It highlights interannual variability in carbon fluxes and enhances our understanding of the responses of these forest ecosystems to extreme weather events. Study results will help in developing climate resilient and sustainable forestry practices to offset atmospheric greenhouse gas emissions and improving simulation of carbon exchange processes in terrestrial ecosystem models.
We examine the effects of demand-side (product market) and supply-side (supply chain) market power on firm profitability and the ease of access to bank financing. Using granular supply-chain and bank-loan information, we empirically demonstrate that both demand-side and supply-side power are associated with higher profitability and greater provisions for bank financing. However, product-market power appears to be marginally more beneficial than supply-chain power. Furthermore, the association between power and performance is non-linear and power beyond an optimal threshold can adversely impact performance. We show that the key insights of our analyses remain robust irrespective of alternative measures of performance, market power, and the nature of customer–supplier interactions. Using a game-theoretic analytical framework, we capture analytical insights consistent with our empirical findings. The novelty of our analyses is in showcasing that firm power emanating from both the demand-side and supply-side operations can significantly ameliorate performance and alleviate external financing constraints.
The reconfiguration graph for the k-colourings of a graph G, denoted Rk(G), is the graph whose vertices are the k-colourings of G and two colourings are joined by an edge if they differ in colour on exactly one vertex. For any k-colourable P4-free graph G, Bonamy and Bousquet proved that Rk+1(G) is connected. In this short note, we complete the classification of the connectedness of Rk+1(G) for a k-colourable graph G excluding a fixed path, by constructing a 7-chromatic 2K2-free (and hence P5-free) graph admitting a frozen 8-colouring. This settles a question of the second author.
In this paper, we consider a two-species predator-prey model in advective heterogeneous environments with the Holling-Tanner interaction term, where the Danckwerts boundary conditions are imposed. Existence, uniqueness, and multiplicity of positive steady state solutions are investigated by using the degree theory and super-sub solution method for predator-prey systems and analyzing the limiting profile. Using the comparison principle for parabolic equations, persistence theory, and constructing Lyapunov functions, we establish various results on the long-time dynamics.
This paper reviews trends in the academic literature on cumulative effects assessment (CEA) of disturbance on forest ecosystems to advance research in the broader context of impact assessments. Disturbance is any distinct spatiotemporal event that disrupts the structure and composition of an ecosystem affecting resource availability. We developed a Python package to automate search term selection, write search strategies, reduce bias and improve the efficient and effective selection of articles from academic databases and grey literature. We identified 148 peer-reviewed literature published between 1986 and 2022 and conducted an inductive and deductive thematic analysis of the results. Our findings revealed that CEA studies are concentrated in the global north, with most publications from authors affiliated with government agencies in the USA and Canada. Methodological and analytical approaches are less interdisciplinary but mainly quantitative and expert-driven, involving modeling the impacts of disturbances on biophysical valued components. Furthermore, the assessment of socioeconomic valued components, including the effects of disturbance on Indigenous wellbeing connected to forests, has received less attention. Even though there is a high preference for regional assessment, challenges with data access, quality, and analysis, especially baseline data over long periods, are hampering effective CEA. Few articles examined CEA – policy/management nexus. Of the few studies, challenges such as the inadequate implementation of CEA mitigation strategies due to policy drawbacks and resource constraints, the high cost of monitoring multiple indicators, and poor connections between scenarios/modeling and management actions were paramount. Future CEA research is needed to broaden our understanding of how multiple disturbance affects forests in the global south and coupled social and ecological systems and their implications for sustainable forest management.
Anti-racist messages educate people about structural racism and argue that indifference and inaction are the foundational building-blocks of race-based inequities. But these messages generate backlash, with several American states banning education about structural racism. We hypothesized that White Americans experience White identity threat and resist anti-racist messages most when they interpret these messages to equalize a lack of anti-racist action (i.e., indifference and silence), treating it as though it were the same as blatant racism. In contrast, we predicted that interpreting anti-racist messages to position silence as a foundational “building-block” for blatant racism would not evoke backlash. In Study 1 (N = 428) ~55% of White respondents in a representative American sample interpreted anti-racist messages as equating indifference with violence, and an equalizing interpretation predicted White identity threat and message resistance. In Study 2 (N = 492) we found that experimentally manipulating anti-racist messages to evoke high vs. low levels of equalizing interpretation led White Americans to feel more White identity threat and in turn be more resistant to both the anti-racist message and anti-racist action in general. In Study 3 (N = 1337) seeing anti-racist messages (vs. no-message) had little effect on White Americans in general, but evoked identity threat and denial of racism among White Americans high in equalizing interpretation who did not interpret the messages as conveying inaction to be a building-block for structural racism. In Study 4a and 4b (N = 789), we reveal a successful nudge for making anti-racist messages less threatening and more motivating for White Americans by using language less likely to evoke an equalizing interpretation.
We propose and investigate a mathematical model on interaction between tumor and the immune system, where the regulation of PD-1/PD-L1 and the stimulation delay of tumor antigen for the immune system are considered. Though delay will not change the structure of equilibria, the global dynamics in the case without delay is simple compared with that in the case with delay. Theoretic analysis and numerical simulations show that the incorporation of delay leads to complex dynamics, including the appearance of oscillating solutions, periodic solutions from Hopf bifurcation, and homoclinic orbits, etc. The effect of the immunotherapy including anti-PD-1/PD-L1 inhibitor and tumor vaccine is also discussed.
Here, we present a protocol for inducing selective lesions in the hippocampal formation of Japanese quail (Coturnix japonica), coupled with associated behavioral testing. We first describe the surgical procedure for aspiration lesions in Japanese quail. We then detail two well-known hippocampus-dependent behavioral tests adapted to birds—foraging array (FA) and spontaneous object recognition (SOR). This protocol is adapted from those used in mammals and can be used to study the involvement of Japanese quail memory centers in declarative memory. For complete details on the use and execution of this protocol, please refer to Damphousse et al. (2022).
Little is known about how rooming house residents perceive how housing influences their health, despite higher morbidity and premature death compared to other Canadians. The social exclusion framework of the Social Knowledge Exchange Network (SEKN) conceptualized by Popay et al. (2008) was used to investigate how rooming houses are linked to health among ten rooming house residents from six rooming houses in Ottawa, Ontario, Canada. Study activities included taking photos to show how living in a rooming house affects health, a community walk-about with the principal investigator, a focus group, and individual interviews. Thematic analysis revealed two broad themes: Housing is Health Care, and Just Managing Today. Findings suggest that structural inequalities and siloed care contribute to the health of rooming house residents, including the balance between poverty and desire to maintain housing, and how residents cope with this stress. If health care providers want to help alleviate the disparities in rooming house residents' health, they need to broaden the lens through which health is conceptualized.
This study explores how the value of sponsored Instagram advertisements (ads) can enhance consumer ad-related involvement (cognitive and affective) and flow experience, which consequently impacts product purchase intention. To comprehend this issue, we propose a framework that combines the extended Ducoffe’s web advertising value model and the Stimulus-Organism-Response (S-O-R) model. We conceptualize S - stimuli - as perceived advertising value of sponsored Instagram ads; O - organism - as consumer ad-related involvements, comprising cognitive, affective, and flow experiences; and R - response state - as purchase intention. Based on an online survey, data was collected from 337 Malaysian Instagram users. The findings indicate that sponsored Instagram ad-related entertainment, informativeness, credibility, incentives, and celebrity endorsement, are conducive to raising the effectiveness of ad-stimuli, which in turn, enhance consumers’ cognitive and affective ad involvement and flow, to influence purchase behavior. The research offers empirical evidence to support the S-O-R framework and helps to expand the scope of sponsored advertising value research and its effect on consumers’ purchase intention. Furthermore, it benefits marketers and advertisers in promoting effective advertising campaigns using sponsored Instagram advertising. It also provides a platform where marketers can design ads that can help them to reach their marketing goals.
Introduction ALRV5XR treatment of androgenetic alopecia (AGA) and telogen effluvium (TE) has early evidence of regenerating a normal scalp hair phenotype in both sexes. Design We performed two 24-week double-blinded placebo-controlled comparison trials, one in each sex, on the ALRV5XR treatment effect on hair regeneration, in AGA and TE, in 92 AGA subjects (24 also had TE). Forty-six women (age 24–64 years) and 46 men (age 22–63 years) were randomized 1:1 to either ALRV5XR or placebo regimens (one b.i.d. oral capsule and daily administration of shampoo, conditioner, and follicle serum). Evaluation Primary outcomes : Absolute and relative changes in terminal hair (TH) density. Secondary outcomes : Response rate, changes in vellus hair (VH) density, TH/VH ratio, hair diameter, growth, and shedding rate. Results Forty-one women (20 ALRV5XR, 21 placebo) and 36 men (17 ALRV5XR, 19 placebo) completed the trials. TH outcome was evaluable for 18 and 21 women and 11 and 11 men (ALRV5XR, placebo, respectively). Efficacy in women: 30.1 THs/cm ² ( p = 0.0002) and 19.7% ( p = 0.0016). Efficacy in men: 21.0 THs/cm ² ( p = 0.0014) and 16.4% ( p = 0.0012). 66.7% of women and 100% of men responded to ALRV5XR. TH/VH ratio for men increased 33.0% ( p = 0.0033). Growth rate in women increased by 30.7 μm/24 h ( p < 0.0001) and 10.0% ( p < 0.0001). There were no adverse events reported. Conclusion and relevance ALRV5XR induced significant regrowth of TH. Accelerating regrowth by reactivation of dormant telogen follicles were the dominant effects in women. Thickening of miniaturized hair and regrowth of dormant telogen follicles contributed equally to the increased TH seen in men (see Graphical Abstract ).
In this case study, I address the procedural ethics of conversation analysis (CA) and the collection of naturally occurring mundane interactions. I draw from the challenges that emerged from the institutional ethics review of the HIV, health and interaction study (the H2I Study), a CA project that sought to identify the practices through which normative assumptions of HIV and other health conditions are produced in conversations. Consistent with CA’s preference for naturally occurring interactions, the H2I Study collected and analysed everyday telephone calls involving people living with HIV. This article offers practical strategies CA researchers might use to navigate two ethical concerns raised about the collection of naturally occurring mundane interactions. The first questions the merits of collecting naturally occurring mundane interactions. For those unfamiliar with CA, the specific advantages of analysing naturally occurring mundane interactions may not be self-evident. This places an evidentiary burden on CA researchers to warrant the collection of this type of data. To address this concern, I suggest demonstrating in ethics applications the analytic value of CA using publicly available interactions. The second concern questions the use of verbal consent necessary for the collection of naturally occurring mundane interactions. Like most CA research, the H2I Study required flexible informed consent protocols appropriate for spontaneous and unpredictable interactions. Drawing from within and outside the CA literature, I offer three rationales for the use of verbal consent. This article is written as a practical resource for conversation analysts seeking approval from their research ethics board (REB) and for REBs who might be unfamiliar with CA research. This article contributes to a small but growing body of literature that documents not only the kinds of challenges CA researchers encounter from institutional ethics review, but the specific procedural ethics they may employ to secure ethics approval.
Following social media influencers is a common activity for social media users. As influencers endeavour to engage followers and increase their power of influence for commercial value, it can result in potential negative consequences to followers' wellbeing. This research explored how social media influencing may cause problematic engagement with influencers. To do so, we drew from attachment theory and used mixed methods, including a Delphi study and a survey with 500 Instagram users. Results suggested that influencer characteristics such as physical attractiveness, social attractiveness, and self-presence, as well as followers' participation comprehensiveness can foster followers' problematic engagement through the mediation of bond- and identity-based attachment (i.e., parasocial relationship and sense of belonging). Importantly, following more influencers weakened the effect of sense of belonging on problematic engagement, but not that of parasocial relationship. Overall, this study sheds light on negative aspects of social media influencing and provides useful insights to gauge social media influencers’ engagement tactics for a healthy follower behaviour and influencer outcomes.
This study examined potential fluctuations in bone metabolic markers across the menstrual cycle both at rest and after a 30-min bout of continuous running at 80% of V̇O2max. Resting and post-exercise (0, 30, 90 min) sclerostin, parathyroid hormone (PTH), carboxy-terminal cross-linking telopeptide of type I collagen (β-CTXI), and procollagen type 1 N propeptide (PINP) were assessed in 10 eumenorrheic women (age: 21 ± 3 y, BMI: 23.2 ± 3.0 kg.m²) during the mid- to late-follicular (FP: day 8.0 ± 1.4) and mid-luteal (LP: day 22.0 ± 2.5) phases of the menstrual cycle. Ovulation was determined using ovulation kits and daily measurement of oral body temperature upon awakening. Menstrual cycle phase was subsequently confirmed by measurement of plasma estradiol and progesterone. On average, resting estradiol concentrations increased from 46.3 ± 8.9 pg·mL⁻¹ in the FP to 67.3 ± 23.4 pg·mL⁻¹ in the LP (p = 0.015), and resting progesterone increased from 4.12 ± 2.36 ng·mL⁻¹ in the FP to 11.86 ± 4.49 ng·mL⁻¹ in the LP (p < 0.001). At rest, there were no differences between menstrual cycle phases in sclerostin (FP: 260.1 ± 135.0 pg·mL⁻¹; LP: 303.5 ± 99.9 pg·mL⁻¹; p = 0.765), PTH (FP: 0.96 ± 0.64 pmol·L⁻¹; LP: 0.79 ± 0.44 pmol·L⁻¹; p = 0.568), β-CTXI (FP: 243.1 ± 158.0 ng·L⁻¹; LP: 202.4 ± 92.3 ng·L⁻¹; p = 0.198), and PINP (FP: 53.6 ± 8.9 μg·L⁻¹; LP: 66.2 ± 20.2 μg·L⁻¹; p = 0.093). Main effects for time (p < 0.05) were shown in sclerostin, PTH, β-CTXI and PINP, without phase or interaction effects. Sclerostin increased from pre- to immediately post-exercise (45%; p = 0.007), and so did PTH (43%; p = 0.011), both returning to resting concentrations 30 min post-exercise. β-CTXI decreased from pre- to post-exercise (20%; p = 0.027) and was still below its pre-exercise concentrations at 90 min post-exercise (17%; p = 0.013). PINP increased immediately post-exercise (29%; p < 0.001), returning to resting concentrations at 30 min post-exercise. These results demonstrate no effect of menstrual cycle phase on resting bone marker concentrations or on the bone metabolic marker response to intense exercise.
This study examines the role of voice practices—formal practices designed to provide employees with opportunities to have a voice—in enhancing organizational innovation. We distinguish between promotive and prohibitive voice practices and extend the distinction to the systemic process level of analysis. Leveraging the contingency and behavioral perspectives, we propose that voice practices (both promotive and prohibitive) mediate the relationship between innovation strategy and organizational innovation, a link mediated by employee voice participation, indicating a two-step mediation process. Our investigation of this two-step mediation model using a national sample of Canadian employers supports our research model. This study shows that managerial actions to enhance employee voice can add value by supporting organizational innovation.
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Jonathan A Newman
  • Office of Research Services
Melody Morton Ninomiya
  • Health Sciences
Colleen Loomis
  • School of International Policy and Governance
Jonathan Mark Wilson
  • Department of Biology
Nichole Scheerer
  • Department of Psychology
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