Master of Science

thesisRecent research has highlighted alarming rates of concussion incidence among female soccer athletes. Studies have demonstrated neck strength as a possible predisposition to concussive forces, but no research has incorporated a dynamic training program emphasizing neuromuscular control related to the cervical musculature. The objective of this study was to investigate the effects of a sport-specific plyometric and functional training program on cervical muscle strength, size, and activation, and subsequent head impacts. An experimental, between-groups design was utilized using high school athletic training and sports facilities. Eight high school female soccer players (age = 16.24 ± 1.07 years; height = 165.89 ± 10.95 cm; mass = 55.17 ± 7.09 kg) participated in the research. An 8 week plyometric and functional training program consisting of 3 sport-specific drills was implemented for the intervention group. The control group did not perform any additional cervical muscle strength training. Isometric cervical neck strength (lbf) was measured using a MicroFET 2 handheld dynamometer, neck girth (cm) was recorded using a standard metric tape measure, muscle activation (% maximum voluntary contraction of the sternocleidomastoid and upper trapezius muscles) was measured using a 16 channel wireless TeleMyo DTS EMG system, and head impact acceleration values (G) were recorded pre- and post-intervention by a DTS 3D 24G Accelerometer. Significant differences were identified between groups related to the mean peak head accelerations between the 3 axes of measurement. Additionally, differences in mean upper trapezius activation (p < 0.001), right sternocleidomastoid (p = 0.002), and left sternocleidomastoid (p < 0.001) muscles were identified over time. No significant group effects were discovered related to neck strength, neck girth, mean acceleration upon impact, or cervical muscle activation or duration throughout heading activities (p ≥ 0.05). The plyometric intervention did not result in significant strength gains compared to the control group, but subjects did reveal a trend in strength gains over time. Functional plyometric training resulted in increased peak head accelerations within the intervention group. The results suggest that plyometric training resulted in greater neuromuscular control and heading force in soccer specific activities, but further research needs to be conducted as it relates to brain injury susceptibility

Spatiotemporal Variations in the Fire Regimes of Whitebark Pine (\u3cem\u3ePinus albicaulis\u3c/em\u3e Engelm.) Forests, Western Montana, USA, and Their Management Implications

Whitebark pine (Pinus albicaulis) is a long-lived tree species that exists throughout high elevation forest communities of western North America. It is the foundation of a diminishing ecosystem that supports Clark’s nutcrackers, red squirrels, grizzly bears, and black bears. The decline of this species is directly related to mortality from widespread mountain pine beetle outbreaks and infestation by the invasive white pine blister rust, and may be exacerbated by fire suppression. Prescribed fire will be a primary management tool in efforts to preserve whitebark pine on the landscape. My research used dendrochronology to investigate the fire history of whitebark pine stands on three mountains in the Lolo National Forest, Montana, via fire-scar and age structure analyses. I then used these data to assess the USDA Fire Regime Condition Classification (FRCC) fire regime types for my sites. Additionally, I utilized traditional superposed epoch analysis techniques in a novel manner to develop a multi-decadal superposed epoch analysis for fire-climate and fire-tree establishment analyses. I sampled between 40 and 50 fire-scarred trees, snags, and remnants, and collected age structure data in two 0.5 ha plots at each site. Samples at all sites recorded a frost event in AD 1601 related to southern hemisphere volcanic activity. The fire-history and stand-structure data indicate all three sites were characterized by mixed-severity fire regimes and generally agreed with the FRCC classifications. However, fires occurred with greater frequency than previously found in whitebark pine forests and distinct differences existed between the fire regimes of each of the three sites that are likely related to topography, forest cover, and climate conditions. A period of widespread fire activity at all three sites occurred from the mid-1700s to the early 1800s and may be the expression of interactions between several climate variables. Fire suppression led to a decline in fire activity in the 1900s, but subalpine fir trees began establishing between 300 and 140 years ago at all three sites. This suggests fire suppression may not be responsible for the advanced succession found in these whitebark pine forests and management decisions based on that assumption are inappropriate for these sites. In addition, the spatial and temporal variability in fire activity between these sites requires a refinement in the Fire Regime Condition Classification methods if they are to be used for managing whitebark pine forests

Anisotropy of Room Temperature Ductility in Haynes 282 Forgings

Haynes 282 is relatively new nickel base superalloy, offering excellent mechanical properties and attracting interest from the gas turbine and aerospace industry. One of the criteria for meeting specification requirement is the room temperature ductility.Forgings of Haynes 282 show large anisotropy in ductility, varying from approximately 25% in longitudinal transverse (LT) to 12% in the short transverse(ST) direction. In this paper LT and ST specimens from forgings were tested for its room temperature ductility.Fractographic and metallographic analysis show the presence of MC and Mc6C carbide banding. Failure in both ST and LT direction was ductile with intergranular fracture, but in the ST direction the failure was preferentially due to cracking of carbides. The orientation of carbides in preferred direction and their excessive segregation affecting ductility in ST is discussed in this work

Adolescents Accounts of Growth Experiences in Youth Activities

Little theory and research exists on the developmental processes that occur during adolescents\u27 participation in extracurricular and community based-activities. As a step in that direction, we conducted 10 focus groups aimed at getting high school students\u27 descriptions of their growth experiences in these activities. The youth reported both personal and interpersonal processes of development. The personal experiences included experimentation and identity work, development of initiative skills such as learning to set goals and manage time, and learning strategies for emotional regulation. The interpersonal experiences included acquiring new peer relationships and knowledge, developing group social skills such as taking responsibility and how to work together as a team, and developing valuable connections to adults. Across domains, adolescents described themselves as the agents of their own development and change. Youth activities appear to be a context in which adolescents arc active producers of development

Synaptic and associative mechanisms mediating Pavlovian conditioning to unpredictable threats

Mental illness is one of society’s most important and pressing challenges. In particular, trauma-related disorders represent some of the most common and debilitating forms of psychopathology that contribute to substantial societal and economic burden. In the laboratory, Pavlovian fear conditioning has been a powerful experimental model for understanding the associative and molecular underpinnings of fear-related behavior. Despite significant advances, our understanding of the circuits underlying conditioned fear is restricted largely to paradigms that have employed highly predictable experimental conditions, largely due to the fact that early theories of associative learning emphasized the importance of predictive relationships in the formation of associative relationships. However, intolerance to uncertainty is argued to be a common feature across fear and anxiety-related disorders and a better understanding of fundamental mechanisms underlying behavioral responses to unpredictable threats may help inform behavioral and brain techniques for intervention. In the current work, we employed an unpredictable backward (BW) conditioning procedure in rodents to examine both the synaptic and associative mechanisms underlying the acquisition and expression of fear to an unpredictable conditioned stimulus (CS). Specifically, we show that NMDA receptors within the BNST play a privileged role in the acquisition of fear to an unpredictable BW CS, whereas those in the CeA are required for the acquisition of fear to both a predictable and unpredictable CS. Next, we examined the associative structure underlying the expression of BW conditioning; we show that the expression of fear to an unpredictable BW CS is mediated by a contextual fear memory and recruits hippocampal (HPC) neurons to a greater degree than a predictable CS. Importantly, chemogenetic reactivation of a BW-tagged HPC ensemble was sufficient to support freezing behavior in neutral context. Lastly, from a translational perspective an important finding was that presentation of the BW CS resulted in the reactivation of a HPC contextual fear memory that was sensitive to disruption by protein synthesis inhibition. Overall, these data provide important insight into the brain mechanisms underlying fear to unpredictable threats

Recreation Effects on Wildlife: A Review of Potential Quantitative Thresholds

Outdoor recreation is increasingly recognised for its deleterious effects on wildlife individuals and populations. However, planners and natural resource managers lack robust scientific recommendations for the design of recreation infrastructure and management of recreation activities. We reviewed 38 years of research on the effect of non-consumptive recreation on wildlife to attempt to identify effect thresholds or the point at which recreation begins to exhibit behavioural or physiological change to wildlife. We found that 53 of 330 articles identified a quantitative threshold. The majority of threshold articles focused on bird or mammal species and measured the distance to people or to a trail. Threshold distances varied substantially within and amongst taxonomic groups. Threshold distances for wading and passerine birds were generally less than 100 m, whereas they were greater than 400 m for hawks and eagles. Mammal threshold distances varied widely from 50 m for small rodents to 1,000 m for large ungulates. We did not find a significant difference between threshold distances of different recreation activity groups, likely based in part on low sample size. There were large gaps in scientific literature regarding several recreation variables and taxonomic groups including amphibians, invertebrates and reptiles. Our findings exhibit the need for studies to measure continuous variables of recreation extent and magnitude, not only to detect effects of recreation on wildlife, but also to identify effect thresholds when and where recreation begins or ceases to affect wildlife. Such considerations in studies of recreation ecology could provide robust scientific recommendations for planners and natural resource managers for the design of recreation infrastructure and management of recreation activities

Documentation of Apollo 15 samples

A catalog is presented of the documentation of Apollo 15 samples using photographs and verbal descriptions returned from the lunar surface. Almost all of the Apollo 15 samples were correlated with lunar surface photographs, descriptions, and traverse locations. Where possible, the lunar orientations of rock samples were reconstructed in the lunar receiving laboratory, using a collimated light source to reproduce illumination and shadow characteristics of the same samples shown in lunar photographs. In several cases, samples were not recognized in lunar surface photographs, and their approximate locations are known only by association with numbered sample bags used during their collection. Tables, photographs, and maps included in this report are designed to aid in the understanding of the lunar setting of the Apollo 15 samples

Preparing Youth to Thrive: Methodology and Findings From the Social and Emotional Learning Challenge

The SEL Challenge was designed in pursuit of two ambitious goals: to identify promising practices for building SEL skills with vulnerable adolescents, and to develop technical supports for use of these SEL practices at scale in thousands of OST settings. The study design included a qualitative methodology, expert practitioners, and performance studies at each of eight exemplary programs. The products of the Challenge - standards for SEL practice and the suite of SEL performance measures - are designed to help OST programs focus deeply on SEL practice, assess their strengths, and improve the quality and effectiveness of their services using a lower stakes continuous improvement approach.By focusing systematically at a granular level of adult and youth behavior, the Challenge content supports use in practice-oriented settings and systems - youth programs, school day classrooms, mentorships, residential treatment, apprenticeships, workplace, families - where the qualities of adult-youth interaction and learning are a primary concern. We hope that local policy makers and funders will use the Challenge as a template for identifying the exemplary SEL services already available in their communities and make sure that they are adequately recognized, resourced, and replicated

Ecology of Depression in Late Childhood and Early Adolescence: A Profile of Daily States and Activities

This study investigated daily states and time use patterns associated with depression. Four hundred eighty-three 5th to 9th graders reported on their experience when signaled by pagers at random times. Depressed youth reported more negative affect and social emotions, lower psychological investment, lower energy, and greater variability in affect. These differences were weaker for 5th and 6th graders, suggesting that self-reported feeling states are a poor indicator of depression prior to adolescence. No differences were found in the daily activities of depressed youths nor in the amount of time spent alone, but depressed youths experienced other people as less friendly and more often reported wanting to be alone, especially when with their families. They also spent less time in public places and more time in their bedrooms. Finally, depressed boys, but not girls, spent much less time with friends, particularly of the same sex, suggesting that social isolation is more strongly associated with depression for boys