Two-Dimensional Transient Spectroscopy Measuring Heterogeneity in Electronic and Rotational Dynamics

Multiple population-period transient spectroscopy (MUPPETS) is a picosecond, time resolved experiment that uses a sequence of six laser pulses. It was previously known that MUPPETS could measure heterogeneity in electronic-state decay. This dissertation presents two projects that extend MUPPETS to new processes. One process is the extension from 2-level system into 3-level system, another new process extends the kinetics from electronic decay to rotational decay. In addition, a third, ongoing project on rotational dynamics in ionic liquids will also be discussed briefly. The first project consisted of two main parts. The first part focused on the biexciton decay in semiconductor nanoparticles. The power dependence of the excited state decay in nanoparticles has been attributed to biexcitons, but those measurements are easily contaminated with other species. New theoretical work in excitonic systems shows that MUPPETS can measure biexciton decays free from contaminations. Our experiments successfully isolate the biexciton decay of CdSe/ZnS core–shell nanoparticles. The biexciton signal shows a highly dispersed, nonexponential dynamics, which is inconsistent with current theories of Auger recombination. The second part of the first project investigated the heterogeneity of exciton decay. There is a fast, nonradiative decay in the exciton decay of core–shell nanoparticles, which has been attributed to a subset of poorly passivated particles. Using a new theory of multi-level systems, our MUPPETS experiments showed that such a subpopulation does not exist. We suggest that the early component in exciton decay is caused by surface relaxation. The second project probed heterogeneity in the local dynamics of polymers, as sensed by solute rotation. The rotation of a solute in a small molecule solvent is exponential, but it becomes nonexponential in a polymer melt. This nonexponential behavior may be explained by either variations in the local viscosity of the polymer—a heterogeneous model—or local anisotropy of the polymer structure—a homogeneous model. To measure heterogeneity in rotation rates, we extended the original MUPPETS experiment to a polarized version. The new method was demonstrated on the anisotropy decay of Pyrromethene 597 in poly(dimethylsiloxane) (PDMS). The results show strong molecule-to-molecule variation in the rotation rate. They are consistent with local, shortlength scale variations in viscosity within the polymer. No evidence for local anisotropy was found. In the final projects, the rotational dynamics of a solute in ionic liquids was measured with 1D polarization experiments. Experiments and simulations have suggested that heterogeneous microstructures exist in ionic liquids. A new signal normalization channel was built to reduce noise, increase long term stability and improve the ability to detect nonexponential decay. Rotational decays are measured for ionic liquids with different chain lengths and different mixture ratio with acetonitrile. Weakly nonexponential decays were found for long chains, but none was found for short chains. Experiments and analysis are ongoing

Improving COVID-19 data protocols for Indigenous peoples in the U.S. and Canada: A public-media-based cross-national comparison

In response to current calls by the World Health Organization and United Nations to prioritize data processes regarding COVID-19 and its impact on Indigenous Peoples worldwide, this exploratory paper aims to briefly identify barriers regarding data processes for Indigenous communities impacted by COVID-19 in Canada and the U.S. Built on emergent themes contributed by current research, the research conducted qualitatively public media analysis to address communication, distrust, and community participation as issues, barriers, and solutions for thorough and accurate data processes. Funding has been a long-term existing and primary issue in addressing these three themes. Federal governments of both countries could better support the Indigenous communities by providing adequate funding, following through with their pledges of support, and sharing detailed, accumulated data with tribal authorities, and tribal epidemiologists. Better communication among federal, state/provincial, and Indigenous community authorities would improve data collection and analysis. Stimulating bottom-up community participation in COVID-19 efforts, not only promotes the data processes in Indigenous communities, but also empowers the local communities’ leadership to develop solution-based responses. This cross-national pilot research sheds light on the necessity of international collaboration advancing Indigenous communities’ health and well-being in both disaster and non-disaster settings

A social work roundtable examining impacts and lessons learned from the COVID-19 pandemic

As have other disciplines, social work has been affected by the COVID-19 pandemic. Societal shifts and service provision gaps have emerged or been amplified over the course of the pandemic. An online roundtable was convened with five Canadian social work leaders to explore impacts of the pandemic on social work as well as to reflect on lingering effects of the pandemic and lessons learned for moving forward. Panelists’ varied substantive areas of social work practice and/or research included youth advocacy, healthcare, social work education and field education, and community development and disaster response. This paper offers a verbatim reproduction of the roundtable including panelists’ reflections on client and community experiences, social worker experiences, workforce impacts, shifts in the way service and practice are conceptualized and delivered, and implications for moving forward. Recommendations are offered in considered disciplinary, interdisciplinary and community advancement.Comme d’autres disciplines, le travail social a été touché par la pandémie de COVID-19. Des changements sociétaux et des lacunes dans la prestation de services sont apparus ou se sont amplifiés au cours de la pandémie. Une table ronde en ligne a été organisée avec cinq leaders canadiens du travail social pour explorer les impacts de la pandémie sur le travail social ainsi que pour réfléchir aux effets persistants de la pandémie et aux leçons apprises pour aller de l'avant. Les divers domaines de fond de la pratique et/ou de la recherche en travail social des panélistes comprenaient la défense des droits des jeunes, les soins de santé, la formation en travail social et la formation sur le terrain, ainsi que le développement communautaire et la réponse aux catastrophes. Cet article propose une reproduction textuelle de la table ronde comprenant les réflexions des panélistes sur les expériences des clients et de la communauté, les expériences des travailleurs sociaux, les impacts sur la main-d'oeuvre, les changements dans la façon dont les services et les pratiques sont conceptualisés et fournis, et les implications pour l'avenir. Des recommandations sont proposées en matière d’avancement disciplinaire, interdisciplinaire et communautaire

Empowered Stakeholders: Female University Students’ Leadership During the COVID-19-Triggered On-campus Evictions in Canada and the United States

The study of disaster-specific leadership of female university students has been largely neglected, especially during on-campus emergency eviction and evacuation. Based on the COVID-19-triggered, on-campus evictions across Canada and the United States, this cross-national partnership examined the out-of-province/state and international female university students’ leadership during the entire eviction process. Through in-depth interviews, this study revealed the female university students’ leadership behaviors during three stages: (1) pre-eviction: their self-preparedness formed an emotional foundation to support others; (2) peri-eviction: their attitude and leadership behavior enabled them to facilitate (psychologically and physically) their peers’ eviction process; and (3) post-eviction: they continued to support their peers virtually and raised the general public’s awareness regarding the plight of vulnerable and marginalized populations. This article argues that the female university students’ leadership that emerged during the eviction process became complementary to and even augmented the universities’ official efforts and beyond. This leadership represents empirical evidence that contributes to the existing literature on gender and leadership by demonstrating female youth as empowered stakeholders rather than as merely passive victims. Future studies could develop detailed stratification of gender and age dimensions in order to portray a more comprehensive picture of the younger generation’s leadership in hazards and disaster research and practice

Audio compression-assisted feature extraction for voice replay attack detection

Replay attack is one of the most effective and simplest voice spoofing attacks. Detecting replay attacks is challenging, according to the Automatic Speaker Verification Spoofing and Countermeasures Challenge 2021 (ASVspoof 2021), because they involve a loudspeaker, a microphone, and acoustic conditions (e.g., background noise). One obstacle to detecting replay attacks is finding robust feature representations that reflect the channel noise information added to the replayed speech. This study proposes a feature extraction approach that uses audio compression for assistance. Audio compression compresses audio to preserve content and speaker information for transmission. The missed information after decompression is expected to contain content- and speaker-independent information (e.g., channel noise added during the replay process). We conducted a comprehensive experiment with a few data augmentation techniques and 3 classifiers on the ASVspoof 2021 physical access (PA) set and confirmed the effectiveness of the proposed feature extraction approach. To the best of our knowledge, the proposed approach achieves the lowest EER at 22.71% on the ASVspoof 2021 PA evaluation set

On the Front Lines: Nonprofits in the Homeless-serving Sector During the COVID-19 Pandemic

This article examines the experiences of the nonprofit, homeless-serving sector during the first wave of the COVID-19 pandemic. Qualitative interviews were conducted with staff and volunteers from frontline organizations in the two largest communities in Nova Scotia, Canada. Participants reported much strain on their organizations' human resources, but also the ability to adjust service delivery mechanisms quickly in order to continue offering supports. Most reported greater in-kind contributions from businesses and community members as well as more funding from the federal government in particular, albeit with administrative burdens and defined timelines. Nonprofits played a leadership role in developing responses to serve the needs of those experiencing homelessness, including developing comfort centres, installing portable toilets in downtown locations, and moving those without housing into hotels. They also advocated to government for state-level responses to those without housing, including calls to invest in new units and enhance funding for frontline service providers. At the same time, nonprofits reported working across sectors, noting better communication and relationships with state actors as well as other nonprofit organizations as a result of their COVID-19 response

KP177R-based visual assay integrating RPA and CRISPR/Cas12a for the detection of African swine fever virus

IntroductionEarly detection of the virus in the environment or in infected pigs is a critical step to stop African swine fever virus (ASFV) transmission. The p22 protein encoded by ASFV KP177R gene has been shown to have no effect on viral replication and virulence and can serve as a molecular marker for distinguishing field virus strains from future candidate KP177R deletion vaccine strains.MethodsThis study established an ASFV detection assay specific for the highly conserved ASFV KP177R gene based on recombinase polymerase amplification (RPA) and the CRISPR/Cas12 reaction system. The KP177R gene served as the initial template for the RPA reaction to generate amplicons, which were recognized by guide RNA to activate the trans-cleavage activity of Cas12a protein, thereby leading to non-specific cleavage of single-stranded DNA as well as corresponding color reaction. The viral detection in this assay could be determined by visualizing the results of fluorescence or lateral flow dipstick (LFD) biotin blotting for color development, and was respectively referred to as fluorescein-labeled RPA-CRISPR/Cas12a and biotin-labeled LFD RPA-CRISPR/Cas12a. The clinical samples were simultaneously subjected to the aforementioned assay, while real-time quantitative PCR (RT-qPCR) was employed as a control for determining the diagnostic concordance rate between both assays.ResultsThe results showed that fluorescein- and biotin-labeled LFD KP177R RPA-CRISPR/Cas12a assays specifically detected ASFV, did not cross-react with other swine pathogens including PCV2, PEDV, PDCoV, and PRV. The detection assay established in this study had a limit of detection (LOD) of 6.8 copies/μL, and both assays were completed in 30 min. The KP177R RPA-CRISPR/Cas12a assay demonstrated a diagnostic coincidence rate of 100% and a kappa value of 1.000 (p < 0.001), with six out of ten clinical samples testing positive for ASFV using both KP177R RPA-CRISPR/Cas12a and RT-qPCR, while four samples tested negative in both assays.DiscussionThe rapid, sensitive and visual detection assay for ASFV developed in this study is suitable for field application in swine farms, particularly for future differentiation of field virus strains from candidate KP177R gene-deleted ASFV vaccines, which may be a valuable screening tool for ASF eradication

Dual-Gendered Leadership: Gender-Inclusive Scientific-Political Public Health Communication Supporting Government COVID-19 Responses in Atlantic Canada

This research aims to identify the influence of woman leadership on improving the traditional man-dominated scientific-political communication towards positive COVID-19-driven public health interventions. Across Canada, dual-gendered leadership (women chief medical officers and men prime minister/premiers) at both federal and provincial levels illustrated a positive approach to “flatten the curve” during the first and second waves of COVID-19. With the four provinces of New Brunswick, Newfoundland and Labrador, Nova Scotia, and Prince Edward Island, Atlantic Canada formed the “Atlantic Bubble”, which has become a great example domestically and internationally of successfully mitigating the pandemic while maintaining societal operation. Three provinces have benefitted from this complementary dual-gendered leadership. This case study utilized a scoping media coverage review approach, quantitatively examining how gender-inclusive scientific-political cooperation supported effective provincial responses in Atlantic Canada during the first two waves of COVID-19. This case study discovers that (1) at the provincial government level, woman leadership of mitigation, advocating, and coordination encouraged provincial authorities to adapt science-based interventions and deliver consistent and supportive public health information to the general public; and (2) at the community level, this dual-gendered leadership advanced community cohesion toward managing the community-based spread of COVID-19. Future studies may apply a longitudinal, retrospective approach with Canada-wide or cross-national comparison to further evaluate the strengths and weaknesses of dual-gendered leadership

Post-Wenchuan earthquake rural reconstruction and recovery in Sichuan China : memory, civic participation and government intervention

On May 12, 2008, an earthquake of a magnitude of 7.9 struck Wenchuan County, Sichuan Province, China, which affected 45.5 million people, causing over 15 million people to be evacuated from their homes and leaving more than five million homeless. From an interdisciplinary lens, interrogating the many interrelated elements of recovery, this dissertation examines the post-Wenchuan earthquake reconstruction and recovery. It explores questions about sense of home, civic participation and reconstruction primarily based on the phenomenon of the survivors of the Wenchuan Earthquake losing their sense of home after their post-disaster relocation and reconstruction. The following three aspects of the reconstruction are examined: 1) the influence of local residents’ previous memories of their original hometown on their relocation and the reconstruction of their social worlds and lives, 2) the civic participation that took place throughout the post-disaster reconstruction, 3) the government interventions overseeing and facilitating the entire post-disaster reconstruction. Based on fieldwork, archival and document research, memory workshops and walk-along interviews, a qualitative study was conducted with the aim of examining the earthquake survivors’ general memories of daily life and specific memories of utilizing space in their original hometown. This dissertation attempts to contribute toward improvement of post-disaster reconstruction (particularly in China) by considering survivors’ social and individual memories, which conveyed their place experience regarding their sense of home in their day-to-day lives in their original home. This understanding is applied to explore the survivor’s sense of home after the post-Wenchuan earthquake relocation and reconstruction. This dissertation argues that the disregard of the social dimension in the relocation and physical reconstruction process resulted in failure of a creation of a sense of place among the inhabitants in the newly-built environment. Discussed also is how the local residents’ previous place-making experience played a pivotal role in the development of a new sense of home and in the process of social reconstruction in the new environment. It is suggested that government should guarantee the physical foundation of the reconstruction and ensure the local residents’ input will be utilized towards enhancing and improving the quality of post-disaster reconstruction, recovery and community resilience.Graduate and Postdoctoral StudiesGraduat