Boydbolt, a positive-latch, simple-release fastener

Fastener /Boydbolt/ has recently been designed to furnish positive lock and release characteristics that positively prevent accidental adverse functions of lock or release

Polygamy and child mortality: Historical and modern evidence from Nigeria’s Igbo

We use historical and modern data on the Igbo ethnic group in Nigeria to assess the relationship between polygamy and child mortality. We examine several possible channels for this correlation, and test its sensitivity to observable characteristics of individuals, households, and regions in order to infer the scope for selection on unobservables to drive the polygamy-child mortality correlation. We find a statistically significant positive relationship between polygamy and child mortality in the modern period, and a statistically insignificant positive relationship in the historical data. Although there is a limited role for polygamist-specific intra-household dynamics and behavioral practices in shaping the mortality of children in such households, the sensitivity of the polygamy-child mortality correlation is consistent with an important role for selection into polygamy, particularly on unobservable characteristics

The Inclusion of In-Plane Stresses in Delamination Criteria

A study of delamination is performed including strength of materials and fracture mechanics approaches with emphasis placed on methods of delamination prediction. Evidence is presented which supports the inclusion of the in-plane stresses in addition to the inter-laminar stress terms in delamination criteria. The delamination can be modeled as a resin rich region in between ply sets. The entire six component stress state in this resin layer is calculated through a finite element analysis and inputted into a new Modified Von Mises Delamination Criterion. This criterion builds onto previous criteria by including all six stress components. The MVMDC shows improved correlation to experimental data

Thriving and Mental Health Outcomes Among Transgender and Gender Non-Conforming Youth in Oregon

A growing body of literature associates transgender and gender non-conforming (TGNC) identity with adverse mental and emotional health outcomes. Only a handful of studies have been conducted using population-based samples of adolescents to study mental health outcomes in TGNC youth (e.g., Eisenberg et al., 2017; Perez-Brumer, Day, Russell, & Hatzenbuehler, 2017; Rider, McMorris, Gower, Coleman, & Eisenberg, 2018; Toomey, Syvertsen, & Shramko, 2018) and only one has looked at outcomes that may indicate thriving (Eisenberg et al., 2017). The current study analyzes data from the 2017 Oregon Heathy Teens Survey (OHTS) (N = 26,747), a population-based biannual survey of eighth and eleventh graders. In 2017, the OHTS included three gender variables: youth report their gender identity, gender presentation (rated on a spectrum from very feminine to very masculine), and perception of others’ evaluation of their gender presentation. The current study examined associations between gender identity and four measures of thriving (emotional/mental health and wellbeing, grades, self-efficacy, and the presence of a caring adult at school) and three measures of adverse mental health outcomes (depressive symptoms, suicidal ideation, and suicide attempt). Multiple and logistic regression were used to test two sets of models. The first set of models included only one indicator of gender identity as a predictor of thriving and adverse mental health outcomes. The second set of models included all three indicators of gender identity as well as interactions between them to provide comparison as to how a more nuanced understanding of gender relates to youth outcomes. Results showed that youth who identified with a TGNC gender identity had the most adverse scores for every outcome compared to their female and male peers. In addition, youth who identified with either a female or a male gender identity, but who reported presenting and/or believing others perceived them as presenting in a non-gender-conforming way (i.e., something other than feminine for females or something other than masculine for males) often reported more adverse outcomes than their fully gender-conforming peers. Finally, outcomes for youth who identified with a TGNC gender identity varied depending on the category of self-presentation or others’ perception that the youth reported. Those outcomes often mirrored results for the gender-conforming gender identity of the category of self-presentation or others’ perception endorsed by the youth (e.g., a TGNC youth who presents as feminine and believes others perceive them as feminine reports lower emotional and mental wellbeing than a TGNC youth who presents as masculine and believes other perceive them as masculine). On this survey, 5.48% of youth claimed a TGNC gender identity, an unprecedented rate for population-based surveys. In addition, only 57.52% of females and 56.04% of males chose the fully gender-conforming options on the self-presentation and others’ perception questions (i.e. feminine for females and masculine for males), a notable outcome given the connection between any degree of gender non-conformity and the lower levels of thriving and higher levels of mental health risk found in this study. Implications include the need for greater support of youth who identify as TGNC, as well as the need for researchers and service providers to not only ask about gender identity beyond the traditional female/male binary, but also to include items on surveys and forms that assess more than one dimension of gender

Youth Wellbeing During the First School Year of the Covid-19 Pandemic: An Intersectional Analysis

During the first full school year of the Covid-19 pandemic, two central contexts for adolescent development—home and school—changed utterly. In Oregon, most middle- and high schoolers attended school entirely remotely from the beginning of the pandemic, in March, 2020, through the end of April, 2021, removing both the supports available and the threats present in in-person school contexts. At the same time, the home context was altered, with parents juggling the implementation of new technology and modes of education for their youth along with parental employment concerns—either working at home with their own needs for technology and physical space or attending work in person under the threat of illness and/or death from Covid-19 (French et al., 2021; Lawson et al., 2020). Supports or harms in physical and social contexts are especially impactful for youth as they undergo rapid development of their cognitive, emotional, and physical systems, and changes in these contexts are likely to impact youth wellbeing (Blakemore & Mills, 2014; Patton et al., 2016). These supports or harms have the potential to affect wellbeing both during the adolescent years and well into adulthood (Chen & Harris, 2019). Influences in proximal contexts like school and home, where adolescents spend most of their time, have the potential to either intensify or buffer social support or hostility for cultural attitudes toward a youth’s developing identity (Masten, 2018; Masten & Shaffer, 2006). The wellbeing of youth with marginalized identities, who are subject to more harmful feedback from the cultural context, may have been particularly impacted, for better or for worse, by the dramatic change in proximal contexts during the pandemic-related disruption of in-person schooling during the first full school year of the pandemic. For these youth, research based on Minority Stress Theory has found that when youth experience cultural hostility related to their identity, youth are likely to internalize that hostility, developing internalized stigma (Meyer, 2003, 2015). Internalized stigma is related to a host of negative mental health, academic, and relational outcomes (Hatzenbuehler & Pachankis, 2016; Meyer, 2003, 2015; U.S. Department of Health and Human Services, 2001). In contrast, when feedback related to youth identity is supportive, the resulting positive identity development may serve as protection against the harms of cultural hostility and bias (K. R. Bogart et al., 2018; García-Coll et al., 1996; Ponzetti, 2016; Tynes et al., 2012). In addition, the climate at school or at home has the potential to either intensify or buffer social support or hostility for cultural attitudes toward a youth’s developing identity (Masten, 2018; Masten & Shaffer, 2006). The U.S. Surgeon General issued a warning in 2021 that youth mental health, facing potential harms at every level of the developmental system, was at increased risk (Office of the Surgeon General, 2021). These risks included increased cultural virulence against youth with marginalized racial/ethnic or identities and youth with disabilities (Office of the Surgeon General, 2021). Some research has found that depressive symptoms and suicidal behavior increased while general mental health declined for youth during the first year of the pandemic (Mayne et al., 2021; Racine et al., 2021). Other research, however, has found that youth reported improved mental health outcomes after the pandemic shut schools down (Patra et al., 2020; Penner et al., 2021; Widnall et al., 2020). From a Minority Stress Theory perspective, if youth have a minoritized identity and have been experiencing amplified cultural hostility in school toward that identity, spending months away from that environment might lessen internalized stigma and improve mental health outcomes. Alternatively, if their parents and family members or others in their home environment are not supportive of their minoritized identity, youth may experience more adverse mental health at home. In school and online, stigma-based peer victimization is a major vector of hostile cultural and community attitudes toward youth with identities that are stigmatized, or minoritized, on the basis of non-dominant gender identity, racial/ethnic identity, or disability status (Lund, 2021; Smith & Juvonen, 2017; Xu et al., 2020). Bullying is related to multiple aspects of youth wellbeing, with well-documented negative impacts on mental and physical health and academic achievement (L. M. Bogart et al., 2014; Juvonen & Graham, 2014; Martín-Castillo et al., 2020; Tang et al., 2020). In addition to these more noticeable impacts, though, bullying also has an effect on a youth’s view of themselves (e.g., their identity development), their society, and their place in that society. Stigma-based peer victimization is one way that oppressive systems are perpetuated, as victims, perpetrators, and witnesses are all immersed in a process in which the power relationships of the larger culture are enacted (Olewus, 1993). Youth with multiple stigmatized identities experience more peer victimization than their peers with fewer or no stigmatized identities (Cyrus, 2017; Garnett et al., 2014; Park et al., 2022) Currently, there is a gap in research involving the wellbeing of youth during the first full school year of the pandemic and especially for youth with marginalized identities and intersectional marginalized identities. Guided by Relational Development Systems Theory and Minority Stress Theory, this dissertation aims to add to knowledge of youth wellbeing during that year, by comparing data from the 2019 Oregon Healthy Teen Survey (N = 28,090) and the 2020 Oregon Student Health Survey (N = 25,762). In this dissertation, I used OLS and logistic regression analyses to explore how youth reports of wellbeing were associated with gender identity, racial/ethnic identity, disability status, and intersections among these aspects of identity by examining two areas of youth wellbeing: mental health and peer victimization (i.e., bullying). The dissertation consisted of two studies. The first examined youth mental health outcomes, and the second analyzed peer victimization outcomes. In Study I, I compared youth mental health outcomes for general emotional and mental health, depressive symptoms, suicidal ideation, and suicide attempt in the 2020-21 school year, the first full school year of the Covid-19 pandemic (referred to in this dissertation as “2020”) with the same outcomes in the 2018-19 school year, the last full school year before the Covid-19 pandemic (referred to in this dissertation as “2019”). In addition, I analyzed whether any differences in outcomes between the two years differed by youth gender identity, racial/ethnic identity, disability status, or intersections among these aspects of identity. In Study II, I compared youth reports of their experience of cyberbullying and stigma-based peer victimization in 2020 to the same outcomes in 2019. As in Study I, I analyzed whether any differences in outcomes between the two years differed by youth gender identity, racial/ethnic identity, disability status, or intersections among these aspects of identity. Together, results from these studies indicated differential experiences during the first full school year of the pandemic among youth with marginalized identities compared to their peers with culturally dominant identities. Youth overall reported more adverse outcomes for general emotional and mental health and depressive symptoms when comparing wellbeing in 2020 to 2019, but were less likely to report suicidal behavior. Youth also were less likely to report bullying on all measures during 2020 compared to 2019. Youth with marginalized identities, especially gender minoritized youth and youth with disabilities, reported more adverse outcomes for general emotional mental health and depressive symptoms than their non-marginalized peers in 2020 compared to 2019. Similarly, although marginalized youth followed the overall pattern in the sample of reporting less likelihood of adverse outcomes for suicidal behavior and bullying in 2020 compared to 2019, the benefit for these groups was smaller than it was for their non-marginalized peers. Each study discusses practical implications of these outcomes and recommendations for policy and practice along with directions for future research. To improve youth mental health, policymakers and program developers should implement programs and policies at local, state, and federal levels that focus on supporting positive identity development related to youth in ways that recognize and honor intersectional identities. To effectively reduce bullying, future research, practice, and policies should focus on the critical importance of whole-school/whole-district programs that focus on positive school climate and culture in identify-affirming ways. To be effective, efforts to improve youth wellbeing must address bias at every level of youth developmental systems, including individual, family, school/school district, community, state, federal, and cultural levels

Quantitative polysaccharide analysis of lignocellulosic biomass

Lignocellulosic biomass is a potential source of fermentable sugars such as glucose. Enzymatic hydrolysis of cellulose is a viable method of solubilizing the glucose from biomass, but the cellulose fraction of native lignocellulosic material is shielded from enzymatic attack by the lignin-hemicellulose matrix surrounding it. Pretreating lignocellulosic biomass with dilute sulfuric acid at high temperatures solubilizes hemicellulose, rendering the cellulose fraction more susceptible to enzymatic hydrolysis. Evaluation of dilute-acid, high-temperature pretreatments depends on polysaccharide analysis of the two fractions resulting from a pretreatment, prehydrolyzed solids(PHS) and prehydrolyzate liquid(PH). The polysaccharide analysis is based on a method described by the National Renewable Energy Laboratory and involves a two-stage sulfuric acid hydrolysis followed by HPLC quantification using ion-moderated partition chromatography and refractive index detection. The subject of this thesis is identifying and quantifying the sources of error associated with the polysaccharide analysis and the error associated with the evaluation of the effects of pretreatment on the polysaccharide fractions of switchgrass and poplar. This was addressed by conducting replicate polysaccharide analyses on single samples of native biomass, PHS, and PH. The variability associated with these measurements was compared to the variability associated with replicate analyses of identically pretreated biomass. It was found that the use of sugar standards to correct for sugar destroyed during the analysis adds error and most likely overestimates the amount of sugar from biomass actually destroyed. It is evident that assuming a volume after neutralization of the hydrolyzed biomass sample is more reproducible than measuring the volume. When using a batch-type reactor and the temperature and acid parameters used in this study,140°C-180°C/ 0.6-1.2 % sulfuric acid (w/w), it is evident that the major source of error in evaluating pretreatment conditions is the pretreatment itself, not the analysis

Utilization of lignocellulosic polysaccharides

Lignocellulosic biomass represents a vast supply of fermentable carbohydrates and functional aromatic compounds. Conversion of lignocellulosics to ethanol and other useful products would be of widespread economical and environmental benefit. Better understanding of the behavior of different lignicellulosic feedstocks in fermentation protocols as well as catalytic activities involved in lignocellulosic depolymerization will further enhance the commercial viability of biomass-to-ethanol conversion processes. The relative toxicity of the combined non-xylose components in prehydrolysates derived from three different lignocellulosic biomass feedstocks (poplar, corn stover and switchgrass, or Panicum virgatum L.) was determined using a Pichia stipits fermentation assay. The relative toxicity of the prehydrolysates, in decreasing order, was poplar-derived prehydrolysates > switchgrass-derived prehydrolysates > corn stover-derived prehydrolysates. Ethanol yields averaged 74%, 83% and 88% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Volumetric ethanol productivities (g ethanol l⁻¹ h⁻¹) averaged 32%, 70% and 102% of control values for poplar, switchgrass and corn stover prehydrolysates, respectively. Ethanol productivities correlated closely with acetate concentrations in the prehydrolysates; however, regression lines correlating acetate concentrations and ethanol productivities were found to be feedstock-dependent. Differences in the relative toxicity of xylose-rich prehydrolysates derived from woody and herbaceous feedstocks are likely due to the relative abundance of a variety of inhibitory compounds, e.g. acetate and aromatic comounds. Fourteen aromatic monomers present in prehydrolysates prepared from corn stover, switchgrass, and poplar were tentatively identified by comparison with published mass spectra. The concentrations of the aromatic monomers totaled 112, 141 and 247 mg(l)⁻¹ for corn stover, switchgrass and poplar prehydrolysates, respectively. The woody and herbaceous feedstocks differed in both amount and type of aromatic monomers. The cellulases of Trichoderma reesei are the most widely studied for use in the depolymerization of lignocellulosics. The Trichoderma cellobiohydrolases CBH1 and CBH2 are traditionally categorized as exo-acting cellulases. A simple individual-based model was created to explore the potential effects of native endo activity on substratevelocity profiles. The model results indicate that an enzyme with a small amount of endo activity will show an apparent substrate inhibition as substrate levels are increased. Actual hydrolysis studies using affinity chromatography-purified CBH2 preparations from three laboratories indicate that CBH2 has native endo activity, while CBH1 does not