A Comparative Analysis of Population Growth Rates in North America

Primary Author: Darcy Bird

Faculty Sponsor: Timothy Kohler

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

Principal topic

When the climate improved at the start of the Holocene (ca. 11,650 years ago), human populations increased dramatically. Many researchers argue that the adoption of agriculture increased fertility to cause the Agricultural Demographic Transition (ADT), which would consequently lead to increased population growth. Zahid et al. 2016, however, found that Wyoming hunter-gatherers had a population growth rate of about 0.04% annually, which is comparable to agriculturalist growth rates. The goal of this research is to use the same methodology to calculate and compare hunter-gatherer and agriculturalist population growth rates.

Method

I used radiocarbon summed probability distributions (SPDs) to represent population. My dataset includes all freely available radiocarbon dates in North America between 6,000 and 300 cal BP.  I used a linear regression and linear mixed effects model to calculate population growth rates. I directly compared the SPD growth rates between early agricultural adopters (before 2000 cal BP), late agricultural adopters (between 2000 and 500 cal BP), and non-agricultural societies. I also subdivided the agricultural sequences to include hunter-gatherer, horticulture, and agriculture phases, as applicable, to see if growth rate changes dramatically within each sequence between each phase.

Results/implications

I found that early agriculture sequences have a higher mean exponential growth rate than non-agricultural societies, while late agricultural adopters have a mean growth rate in between. These results contradict Zahid et al.’s conclusion that hunter-gatherer and agriculturalist societies have comparable growth rates. They also support the conclusion that the ADT prompted a dramatic population increase during the Holocene.

Differences in Caregiver and Child Factors Considering the Birth Order of Children with ASD

Primary Author: Sarah Boland

Faculty Sponsor: Tammy Barry

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

Principal Topic: Though research has investigated the ways in which caregiver factors are associated with one another (Kuhn & Carter, 2006), there is limited research on how these factors differ across varied family structures. Given the heightened distress among parents of children with autism spectrum disorder (ASD) and the reliance of parent report in clinical evaluation, it is essential to understand how nuances in family structure may impact such reports.

Method: Participants were 155 caregivers with either (1) a “first-born” child with ASD and then typically-developing (TD) child(ren); (2) TD child(ren) and then a “not-first-born” child with ASD, or (3) an “only child” with ASD. Caregivers completed questionnaires assessing parental and child factors.

Results/Implications: Correlations among parent and child variables by birth order indicated many significant correlations across conditions; however, the correlation between efficacy and knowledge was only significant for the only-child group, r = -.243, p = .03. One-way ANOVAs indicated the three birth orders did not differ significantly on caregiver distress, family resources, ASD symptom severity, and child externalizing behaviors. However, some group differences emerged: not-first-born higher for satisfaction; first-born lower for efficacy; only-child lower for ASD knowledge and higher for child internalizing behaviors (overall) and perceived social support (compared to first-born). Results suggest having a TD child first may enhance feelings of readiness as a parent. Having multiple children may also increase parents’ actual knowledge of ASD. This finding, in combination with the only-child condition’s negative correlation between efficacy and knowledge, prompts the need for further research.Bottom of Form

Parenting Daily Hassles and Pessimism Moderate the Relation between ASD Symptom Severity and Parental Expressed Emotion

Primary Author: Aurora Brinkman

Faculty Sponsor: Tammy Barry

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

Principle Topic: Expressed emotion (EE) is the amount of criticism, hostility, and emotional over-involvement in family relationships. EE is common in families who have a child with autism spectrum disorder (ASD) and can lead to worse outcomes for families, including greater physical and mental health problems for the caregivers and more severe child behavior problems. Past research has shown that stress and parenting style affect EE, but more research is needed to understand factors that impact EE. This study examined how intensity of parenting daily hassles and pessimism (both risk factors) impacts the relation between ASD symptom severity and EE (specifically criticism) over time.

Method: Participants were 127 caregivers who completed two online surveys (via Qualtrics) one year apart. At Time 1, caregivers completed measures assessing demographics, child ASD symptom severity, intensity of parenting daily hassles, and parental pessimism. At Time 2, they completed a questionnaire assessing parental criticism.

Results/Implications: Overall, ASD symptom severity related to parental criticism over time. Intensity of parenting daily hassles and pessimism at Time 1 each interacted with ASD symptom severity in predicting parental criticism. Parental criticism was high when the intensity of parenting daily hassles was also high, regardless of ASD symptom severity, or when both pessimism and ASD symptom severity were high.

The results indicate areas for clinical intervention when working with families with children with ASD. Addressing daily parenting hassles and reducing pessimism through positive coping strategies may lead to a reduction in EE, improving caregiver mental health and child behavior.

Customized Porous Materials for Selective Separation via Confinement Effect

Primary Author: Derek Deming

Faculty Sponsor: Qiang Zhang

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

Metal–organic frameworks (MOFs) have been subject to extensive research in recent years owing to their diverse porous molecular frames and adaptability to targeted applications. MOFs are comprised of inorganic nodes and organic linkers that can be tailored to suit a prodigious scope of applications, such as catalysis, sensing and separations. One of the most important separations is isolating xenon (Xe) from a mixture of xenon and krypton (Kr). Not only is Xe scarce and an important inert gas used in a variety of purposes (i.e., aerospace, electrical, and medical industries), the capture of Xe from gas mixtures embodies one of the most challenging molecular gas separations. In this work, we have designed a series of novel MOFs based on customized “v-shaped” organic linkers with electron donating and/or withdrawing groups to investigate the role of structure and functional groups in the separation of Xe via the “confinement effect”. Computational results suggested that a series of symmetrical diaryl sulfone and dimethyl-4,4’-oxalyldibenzoate linkers provide the most promising selectivity due to their ideal pore size, approximately 5 Å, to immobilize Xe molecules. These MOFs were comprehensively characterized via x-ray diffraction (single crystal and powder x-ray diffraction), nitrogen adsorption isotherm analysis, ultraviolet-visible and Fourier transform infrared spectroscopy. The role of pore size, shape, and functional groups will be extensively explored to help us gain deep insights into the vital factors influencing Xe adsorption. The goal of the project was to design and synthesize ideal materials for the separation of Xe from gas mixtures.

The genetic consequences of dam removal on the Elwha River for recolonizing Steelhead

Primary Author: Alexandra Fraik

Faculty Sponsor: Joanna Kelley

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

Dam construction and riverscape habitat fragmentation disrupt important life-histories and movement of aquatic species. Functionally, dams disrupt the movement of water, sediments, nutrients, and species between upstream and downstream. The Elwha and Glines Canyon dams in Washington state, constructed in the early 1900s, fragmented the Elwha River, restricting migratory species such as Oncorhynchus mykiss from ocean. Oncorhynchus mykiss exhibits multiple life-history phenotypes including a migratory form (anadromous Steelhead) and a freshwater non-migratory form (resident Rainbow Trout). The negative effects of dams on O. mykiss have been extensively documented (including population declines, loss of genetic diversity, extirpation), however few have studied their population genetics following dam removal. In 2012 and 2015, the Elwha River dams were removed and anadromous Steelhead recolonized formerly dammed regions. In this study, we characterized the genetic ancestry of recolonizing Steelhead into the previously dammed portions of the Elwha River watershed. Single nucleotide polymorphism genetic data were produced from 1,003 samples collected prior to, during and post dam removal from both life-history forms. Population structure analyses supported three genetic clusters primarily explained by dam location. Following dam removal genetic structure decreased. Using genetic stock identification, we determined recolonizing Steelhead were of mixed genetic ancestry with individuals derived from formerly dammed populations as well as below dam populations. Alleles putatively involved in the anadromous phenotype were detected in formerly dammed populations both prior to and post dam removal. These results have significant evolutionary implications for the conservation of migratory adaptive potential in O. mykiss populations facing changing riverscapes.

Comparing Mother and Child Functioning among Preschoolers Attending Head Start and Private Preschools: The Importance of Father Involvement

Primary Author: Robyn Herbert

Faculty Sponsor: Tammy Barry

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

Principal Topic

Fathers are more involved with their children compared to previous generations, making habits as parents important to family involvement research (e.g., Opondo et al., 2016). Research has demonstrated that increased levels of father involvement have been related to beneficial outcomes for children including academic achievement (e.g., Jeynes, 2015). Father involvement may be particularly important for families with a socioeconomic disadvantage (Atzaba-Poria et al., 2004). The current study examined mother and family variables as they relate to child behaviors, whether these variables differ due to Head Start status or family structure, and how these variables relate to spousal stress in two caregiver homes.

Method

Participants included 130 children and their mothers. Participants were recruited from Head Start centers and private preschools. Mothers completed the study questionnaires; children were tested at Head Start or their preschool.

Results/Implications

Results indicated children with a father in the home had higher cognitive functioning and their mothers used fewer negative parenting practices. Results also indicated that children who attend Head Start were more likely to have an absent father; however, if a father was present, mothers of children in Head Start experienced significantly lower levels of spouse/partner stress. The current study adds to previous research demonstrating that increased father involvement can benefit children and mothers. These results highlight points of intervention for children in Head Start, who may otherwise experience health and academic inequity. Results may inform family-based interventions in which mothers’ mental health is targeted in an effort to reduce negative parenting practices.

Stigma As a Moderator for the Relation between Race and Autism Spectrum Disorder Diagnoses

Primary Author: Shelby Johnson

Faculty Sponsor: Tammy Barry

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

Principal topic: Past research has indicated that minority racial and ethnic groups in the United States face more barriers to accurate and timely autism spectrum disorder (ASD) diagnoses than their white counterparts. This project is designed to determine if stigma moderates the relation between race and the time lapse between symptom onset and ASD diagnosis.

Method: Data were collected from 152 parents of children with an ASD diagnosis. Parents reported at what age their child began showing signs of ASD, what age the child was officially diagnosed with ASD, and child’s race; they also completed a stigma scale measuring affective, behavioral, and cognitive stigma.

Results/implications: A t-test indicated that the time lapse between symptom onset and diagnosis did not significantly differ between white and non-white participants. Furthermore, the time lapse between symptom onset and diagnosis did not significantly relate to stigma. However, a regression analysis indicated that stigma moderated the relation between race and the time lapse in diagnosis when comparing white participants (n = 123, M = 21.63, SD = 17.36) to non-white participants (n = 29, M = 17.66, SD = 18.86) p = .02. These data suggest race and stigma play a significant role in how long it takes a child to receive an ASD diagnosis. Although neither race nor stigma individually related to the time lapse between onset and diagnosis, their interaction was significant. Parents of minority children who reported experiencing higher levels of stigma also reported the shortest time lapse between symptom onset and diagnosis.

The Effects of Absolute Status, Relative Status, and Patriarchal Culture on the Victimization of Women: An International Comparative Study

Primary Author: Sohee Kim

Faculty Sponsor: Melanie-Angela Neuilly

Primary College/Unit: Arts and Sciences

Category: Physical and Social Sciences

Campus: Pullman

Abstract:

A rising number of concerns about violence against women has resulted in various explanatory theoretical frameworks being emerged and developed. For example, several feminist theories have shed light on the role of women’s socioeconomic status and gender stratification relative to men in order to predict violence against women. Meanwhile, another branch of feminist theory argues that female victimization stems from the cultural disadvantage women incur in the patriarchal structure. Evidence has far been inconclusive, however. To fill this gap, we investigate the following questions: Which indicators are more predictive of women’s victimization? Will patriarchal culture play a role in explaining violence against women? To answer these questions, this study uses a multilevel mixed-effects model with logit link functions with a dataset comprising 36,286 respondents from 54 nations. Results show that women with higher absolute and relative status are victimized at higher rates at the individual-level, only supporting the backlash hypothesis. Among country-level variables, absolute status and relative status of women indicate significant effects, but the Marxist feminist argument is also supported. Furthermore, there is a significant positive association between patriarchal culture and women’s victimization. These results indicate we should deliver the message saying that improving gender equality is not the signal of threats to men’s rights in society, rather it is given rights for women.