VictorJuiz/thesis huggingface dataset:
Nonlinear and Ultrafast Optical Probing of Nanoscale MnAs and Graphitic Films
Keywords: graphene
MnAs
nonlinear optics

This thesis reports on ultrafast linear and nonlinear optical probing of nanometer thick films. Exfoliated graphene and few-layer graphite are probed through optical second harmonic generation (SHG) with 800 nm, 150 fs pulses. Samples of varying thickness from 1 carbon layer to bulk graphite are deposited onto an oxidized silicon substrate. SHG measurements are taken as a function of azimuthal rotation angle of the films. It is found that the SHG from graphene is much weaker than that from bilayer graphene, and has a qualitatively different azimuthal pattern. As the sample thickness increases from bilayer graphene to bulk graphite, the SHG yield generally decreases. Both of these effects are explained in terms of the symmetry of graphene and graphite, and modeled using multilayer optical transfer matrices, and an identical set of nonlinear susceptibility tensor elements for the front and back surfaces. These tensors are independent of sample thickness. MnAs films of 150 and 190 nm thickness on (001)GaAs are optically excited with 775 nm, 200 fs pump pulses. Specular SHG at 388 nm and first order optical diffraction at ∼ 400 nm are used to probe the samples on timescales up to 2 μs. It is found that the SHG probes the temperature-dependent, spatially averaged, surface strain. This strain reaches a maximum deviation in ∼ 6–100 ps after optical excitation depending on the pump fluence and initial temperature. The strain then recovers in hundreds of picoseconds, a timescale consistent with heat diffusion. The optical diffraction probes the first Fourier component of the paramagnetic–ferromagnetic stripes inherent to MnAs films in the 10–40◦C temperature range. After optical excitation, the diffraction data show highly nonthermal behaviour in the MnAs films. If a sample is excited from the coexistence phase, the diffraction signal shows decaying oscillations with a period of ∼ 335±4 (408±4) ps for the 150 (190) nm films; this is consistent with the release of a standing acoustic wave. Decay occurs on a timescale of ∼ 2 ns consistent with local diffusion through the films. The stripes are restored on a timescale of hundreds of nanoseconds, with a temporal behavior consistent with a diffusion process, possibly thermal in origin.
The Development of Language and Reading Skills in Emergent Bilingual Children
Keywords: Bilingualism
Literacy

This dissertation examined language and literacy development in English-Hebrew emerging bilinguals. During their senior kindergarten year, one group of children participated in a bilingual English-Hebrew program (“early” group; n = 17) while another participated in an English-language program with minimal Hebrew instruction (“late” group; n = 19). Both groups were merged in Grade 1 and continued to receive a partial Hebrew immersion program. The first part of this dissertation explored longitudinally how an early partial Hebrew immersion program contributes to literacy (word reading, pseudoword reading, reading comprehension), language (vocabulary and morphological awareness (MA)), phonological awareness, and rapid automatized naming in English and Hebrew. Similar improvement from senior kindergarten to Grade 1 was noted for both groups across all measures, however the early group displayed significantly stronger Hebrew vocabulary skills. Literacy and language inter- and cross-linguistic correlation patterns were not significantly different between the two groups. The second part examined the relevance of the Simple View of Reading framework (SVR; Gough & Tunmer, 1986) in Grade 1 (N = 36). The contribution of word reading and language proficiency was examined within and between languages. Two aspects of MA (derivational awareness and inflectional awareness) were considered as additional components of oral language. Word reading, vocabulary and both MA measures were used as predictors. The SVR model significantly explained English reading comprehension based on a combination of word reading and derivational awareness (but not vocabulary), and Hebrew reading comprehension based on word reading and vocabulary. In English, derivational awareness contributed unique variance to reading comprehension above word reading although this was not the case in Hebrew. In addition, English word reading and inflectional awareness predicted Hebrew reading comprehension, thus supporting the SVR model cross-linguistically, although the reverse was not true. Overall, the children attending the Hebrew early immersion programming had an advantage for Hebrew vocabulary skills with no negative repercussions on their English language and literacy skills. The study supports the relevance of the SVR framework for young emerging bilinguals, and underscores the importance of considering aspects of MA as components of oral language proficiency that contribute to reading comprehension in these learners.
Predicting Antisocial Behavior: How Callous-unemotional Traits Moderate Common Risk Factors
Keywords: Callous-Unemotional Traits
Antisocial Behavior
Conduct Disorder
DSM-5

Callous-unemotional (CU) traits are associated with severe and aggressive youth antisocial behavior (ASB) and are under consideration as a potential specifier for the diagnosis of Conduct Disorder in DSM-5 (Frick & Moffitt, 2010). This proposal demands more inquiry into the impact that CU traits have on behavioral subtypes of youth ASB. Normal-range personality traits, trait levels of anxiety, and hormonal stress reactivity (i.e., changes in the stress hormone, cortisol) are all factors that have been studied extensively in relation to ASB, but these relationships have not yet been considered in combination with CU traits. The purpose of the current set of studies was to examine the extent to which CU traits moderated links between these three factors and both overall and behavioral subtypes of ASB. In the first study, data were collected on children’s personality, CU traits, and three behavioral categories of ASB (physical aggression, relational aggression and non-violent rule-breaking behavior) for community (N = 742) and clinical (N = 183) samples of children. In the community sample, CU traits moderated links between Neuroticism, Extraversion, Agreeableness, Openness to Experience and ASB overall and externalizing behaviors, between Neuroticism, Extraversion and physical aggression and between Agreeableness, Extraversion and rule-breaking behaviors. In the clinical sample, CU traits moderated the link between Agreeableness and externalizing behaviors. In the second study, data were collected on children’s trait anxiety, CU traits, and the same three behavioral categories of ASB in a follow-up adolescent community sample (N = 145). Reactivity of cortisol in response to an unanticipated social stress test was also measured. Results revealed that CU traits moderated links between trait anxiety and ASB overall, externalizing behaviors and physical aggression. In females only, CU traits also moderated links between cortisol reactivity and ASB overall and externalizing behaviors. Combined, the results of these studies support the proposal that CU traits are a clinically useful diagnostic specifier with different implications for behavioral subtypes of ASB. Further, the present findings allow recommendations to be made for future research to further our understanding of the role CU traits play in CD, and to develop targeted interventions.
Moved to Learn: Dalcroze Applications to Choral Pedagogy and Practice
Keywords: choral
Dalcroze Eurhythmics

Over a century ago, Émile Jaques-Dalcroze (1865-1950) began experimenting with a pedagogical approach that would give students access to their personal musical voice and a system of technique to express that voice with ease and sensitivity. Music education had lost sight of certain key qualities of exceptional musicianship; qualities such as flow, nuance, imagination, and individuality, so valued in expressive performance, were absent in music pedagogy. According to Jaques-Dalcroze, the antidote to musical arrhythmy (a lack of musical ease and expressivity) lay in the integrated use of the whole body in both musical perception and performance, a coordination he termed eurhythmy. The purpose of this study is to investigate the applications of Dalcroze Eurhythmics to the choral context, including the ways in which the Dalcroze approach shapes the philosophical, pedagogical and musical outcomes of choral pedagogy and practice. More specifically, how do these two areas interact in relationship to the following topics: (1) conductor, chorister and choir as instrument, (2) conductor and chorister score study, (3) conductor and chorister gesture, and (4) choral pedagogy and rehearsal techniques? The original writings of Émile Jaques-Dalcroze provide a framework for the discussion, while interviews with two groups, Dalcroze master-teachers with choral conducting training and/or experience, and Dalcroze-trained choral conductors illustrate the specific applications of the choral context. Study participants reported the use of the Dalcroze approach for three main purposes in the choral context: (a) to develop choral skills, including vocal skills, aural skills, kinesthetic skills, ensemble skills and music literacy skills; (b) to prepare the whole body for accurate and expressive performance of choral repertoire (conducting and singing); and (c) to develop non-musical outcomes that support choral conducting and singing, including mental acuity, creativity, a contextualized view of self and others, self-confidence and risk-taking, and enjoyment in music making.
The Role of the Rho GEF Arhgef2 in RAS Tumorigenesis
Keywords: RAS
Arhgef2
MAPK signaling
Cancer

Tumorigenesis is driven by the sequential accumulation of genetic lesions within a cell, each which confer the cell with traits that enable its abnormal growth. The result is a mass of dysregulated cells, or tumor, which, upon further mutation, may spread, or metastasize, to other organs of the body. The dissemination of tumor cells makes treatment difficult, and thus confers cancer with its associated lethality. Over the past 30 years, the RAS genes have been critical in teaching us the mechanisms underlying the molecular progression of cancer. RAS is mutated in 33% of all cancers and is often an early event in its stepwise progression. As a result, the RAS genes are widely accepted as ‘drivers’ or ‘initiators’ of human tumorigenesis. Unfortunately, efforts directed at targeting RAS in the clinic have as of yet been unsuccessful. This has triggered a need to identify genes that are required for RAS tumorigenesis that are therapeutically tractable. My research has focused on deciphering the potential role of the Rho GEF Arhgef2 in RAS-mediated tumorigenesis. I have found that Arhgef2 is a bona fide transcriptional target of RAS and is upregulated in human tumors harboring RAS mutations. Importantly, depletion of Arhgef2 in RAS-mutated cells inhibits their survival, proliferation, and tumor growth in murine models. In search of the mechanism underlying the requirement of Arhgef2 in RAS tumorigenesis, I have uncovered a novel function for Arhgef2 as a positive regulator of a central RAS pathway, the mitogen-activated protein kinase (MAPK) pathway. Thus, Arhgef2 is part of a positive feedback loop in which RAS-dependent increases in Arhgef2 expression results in the amplification of RAS signaling. Moreover, Arhgef2 confers tumor cells with properties favoring their malignant conversion, thereby implicating Arhgef2 in the formation of metastases. Together, these studies suggest that Arhgef2 plays an important role at multiple stages of tumorigenic progression and may therefore be a promising therapeutic target in RAS-mutated tumors.
The Epidemiology of Diabetes among Immigrants to Ontario
Keywords: epidemiology
diabetes
ethnicity
immigration
public health

Type 2 Diabetes Mellitus (T2DM) prevalence is increasing globally with roughly 2.4 million people currently living with this condition in Canada. T2DM occurs more commonly in non-European ethnoracial groups, however the distribution of risk by age, sex, ethnicity and immigration status in Canada are not completely understood. The purpose of this thesis is to investigate the epidemiology of diabetes in an immigrant, multi-ethnic population using linked immigration and health data for the province of Ontario. The ultimate goal of this work is to generate information that can be used to design appropriate and effective targeted programs for diabetes prevention, management and control in order to reduce inequities in health. The principal findings of this work indicate that: 1) South Asians had a three-fold higher risk for developing diabetes as compared with people of European ethnicity and this disparity in risk was evident at a very young age; 2) The young age at diabetes onset experienced by many of our high-risk ethnic groups, including South Asians and people of African and Middle Eastern descent, suggest that in order to capture an equivalent risk of disease, screening may be recommended up to 15 years earlier in these groups – which is not reflected in current screening guidelines; 3) Contrary to patterns seen in Western European populations, women belonging to many high–risk ethnicities had equivalent or, in some cases, higher risk than men; 4) Risk varied substantially across country and region of birth making broad definitions of race or ethnicity (eg. ‘Asian’ or ‘Black’) inappropriate. These findings emphasize the heterogeneity of risk experienced by different ethnoracial populations in Canada and suggest that targeted primary prevention programs aimed at young adults and adolescents belonging to high-risk ethnic groups may be warranted. In addition, screening guidelines may need to be updated to reflect the younger age at onset in these populations. Further research is necessary to identify culturally appropriate and effective programs to reduce diabetes risk and associated health problems in these populations.
Typologies of Movement in Western Percussion Performance: A Study of Marimbists' Gestures
Keywords: Marimba
Movement
Percussion
Gesture

Musicians are on stage not only to be heard but also to be seen. The visual aspects of music are a crucial part of the experience. Whether performers move too much or too little for a particular audience member, their gestures are often noticed. Some audiences may enjoy certain gestures while others may find them distracting. To study this topic in greater detail, I view my research through the lens of marimba performance. The marimba is a large instrument that can involve many movements to produce a sound. The way marimbists move while playing is noticed due to the nature of the instrument. When I interviewed ten professional marimbists in a 2011/2012 study, most participants discussed distracting gestures as a negative part of performance and said that they try to avoid extra gestures unless they relate to the music. The same participants were video recorded performing four excerpts from standard marimba repertoire by Gordon Stout, J.S. Bach, and Keiko Abe. The results of the analysis include: 1) gesture repetition in multiple takes of the same excerpt; 2) movement-areas of the body that I observed most in each participant; 3) a comparison of each participant to the others; and 4) results, patterns, and trends. This research also includes a discussion of literature in visual aspects of music performance, insight to why performers move the way that they do, an explanation of “sound producing” versus “ancillary gestures”, and a detailed discussion of my research study. Although this study will not lead to conclusions that can be applied to all marimbists, it will, however, provide an important contribution to physical gesture research in music performance by presenting patterns and trends from a comparative study of ten professional musicians.
The Effects of Gabapentin on Pre-operative Anxiety, Morphine Consumption and Pain after Surgery.
Keywords: gabapentin
opioid sparing
acute pain
pain catastrophizing
preoperative anxiety
anxiety

Gabapentin is an anticonvulsant that has become a treatment option for several indications that are not approved by Health Canada. Commonly, gabapentin is prescribed for neuropathic pain and anxiety disorders. The objective of this dissertation was to evaluate the efficacy of gabapentin for reducing pre-operative anxiety, post-operative pain and opioid consumption. The initial study examined regimens of pre-operative and post-operative gabapentin given to patients undergoing total knee arthroplasty. Patients that received gabapentin postoperatively used significantly less morphine at 24 hrs, 36 hrs and 48 hrs (p<0.05). Furthermore these patients had significantly better active-assisted knee flexion on postoperative day (POD) 2, POD 3, with a trend toward better flexion on POD 4. Next, we examined whether: 1) gabapentin administration reduces pain and opioid use after total hip arthroplasty using a multimodal analgesic regimen that included spinal anesthesia; and whether 2) preoperative administration of gabapentin is more effective than postoperative administration. Our results demonstrated that whether a 600 mg dose of gabapentin was given preoperatively or postoperatively, patients’ postoperative morphine consumption or pain scores were not reduced in hospital nor was there a reduction in pain 6 months after hip arthroplasty. The third study found that a single dose of 600 mg of gabapentin was not sufficient to reduce preoperative anxiety in patients prior to hip arthroplasty. In contrast, the final study demonstrated that 1200mg of gabapentin reduced pre-operative anxiety and pain catastrophizing in female patients with moderate to high levels of preoperative anxiety prior to major surgery, but also increased preoperative and early postoperative sedation. Our findings demonstrate the efficacy of perioperative gabapentin with respect to preoperative anxiety reduction and decreasing morphine consumption after surgery. Future studies that focus on the optimal dose and duration of perioperative gabapentin, with the aim of improving functional outcomes and decreasing the incidence and severity chronic post-surgical pain are warranted.
Biomaterial-based Strategies to Build Vascularized Modular Tissue Engineered Constructs
Keywords: tissue engineering
biomaterials

Survival of engineered tissues in vivo requires the presence of an internal vascular network and immediate connection to the host vasculature. Modular tissue engineering approaches the vascularization ‘design’ requirement through fabrication of submillimeter-sized collagen microtissues (‘modules’) with endothelial cells (EC) seeded on the surface of the modules and functional or vascular support cells inside the modules. Several modules are then packed together to build a larger tissue. In this work, we explored biomaterial-based strategies to build vascularized modular tissue engineered constructs. A photocrosslinkable poloxamine-polylysine acrylate biomaterial was first synthesized to improve the mechanical limitations of collagen modules under flow, while still supporting EC attachment. An extracellular matrix (ECM)-based strategy was then explored to enhance the vascularization of the modules in vivo. Manipulation of the ECM was accomplished through lentiviral transduction of EC to overexpress Developmental endothelial locus-1 (Del-1), a pro-angiogenic ECM molecule. Supporting the hypothesis that Del-1 overexpression ‘tilts’ the balance in EC from a quiescent to a pro-angiogenic phenotype, human umbilical vein endothelial cells transduced to overexpress Del-1 (Del-1 HUVEC) formed more sprouts and had a distinct expression profile of angiogenic genes in vitro, relative to control eGFP HUVEC. While very few blood vessels formed upon subcutaneous injection of empty collagen modules coated with Del-1 or eGFP HUVEC in a SCID/Bg mouse model, embedding adipose derived mesenchymal stem cells (adMSC) inside the modules increased blood vessel formation. Moreover, Del-1 HUVEC and adMSC modules consistently had more blood vessels (donor-derived and total number of vessels) compared to eGFP HUVEC and adMSC, over the 21 day duration of the study, with the greatest difference observed at day 7 post-transplantation. In addition, more α-smooth muscle actin (SMA+) staining was observed in Del-1 implants compared to eGFP, suggestive of increased vessel maturation through recruitment of SMA+ pericytes and smooth muscle cells. Perfusion studies showed that the implant vasculature was connected to the host vascular network as early as day 7, and throughout the 21 day duration of the study, for both Del-1 and eGFP implants. Nevertheless, further normalization of the vasculature is likely required to improve perfusion at early time points after transplantation.
Exploring the Pathophysiology of Chronic Depression: The Interplay between Depression, Cortisol Responses, and Personality
Keywords: cortisol
chronic depression
social stress
personality
neuroticism
extraversion
hypothalamic-pituitary-adrenal

Chronic major depressive disorder (CMDD) is a common and debilitating illness. Its pathophysiology needs further elucidation, before more effective targeted treatments can be developed for this condition. To gain a better understanding of the psychobiology of CMDD, three interconnected studies were conducted that examined the interplay between chronic depression, cortisol responses, and personality. Study 1 examined cortisol responses to the Trier Social Stress Test (TSST) in CMDD participants (n=29) as compared to healthy controls (n=28). It was hypothesized that cortisol responses would be greater in the CMDD population. Results indicated that females with CMDD had increased cortisol output compared to female controls, a pattern consistent with the hypothesis. However, males with CMDD had decreased cortisol responses compared to male controls. These results suggest that cortisol responses to social stress are altered in those with CMDD; however, females and males experience fundamentally different changes. Study 2 examined moderating effects of personality on cortisol responses to the TSST in those with CMDD (n=51) as compared to healthy controls (n=57). It was hypothesized that higher neuroticism and/or lower extraversion would be associated with increased cortisol responses in CMDD participants. As hypothesized, lower extraversion was associated with increased cortisol reactivity in those with CMDD but not in healthy controls. However, no association was found between neuroticism and cortisol responses. These findings could support the notion that lower extraversion is a vulnerability marker for chronic depression and thus a possible target for treatment. Study 3, evaluated the cortisol awakening response (CAR) in CMDD participants (n=27) compared to healthy controls (n=30). It was hypothesized that such awakening responses would be more pronounced in the depressed population compared to controls. Contrary to expectation, no differences were found between the groups. However, lower extraversion was associated with a lower CAR in both CMDD and healthy controls, a finding that was not anticipated a priori. These interconnected studies suggest that examining relationships between depression, cortisol responses, and personality, can assist with identifying distinct psychobiological profiles in those with chronic depression. It is proposed that this strategy will improve the likelihood of developing more targeted treatments for this population.