Probabilistic seismic hazard analysis for acceleration-sensitive nonstructural components attached to shear wall structures

This thesis focuses on quantifying demands for acceleration sensitive nonstructural components (NSCs) attached to inelastic shear wall structures. The proposed probabilistic method lends itself to performance based engineering (PBE), which can mitigate casualties, injuries, and property losses through the identification of performance target and the explicit quantification of seismic performance by taking into account the most important sources of uncertainty in seismic behavior prediction. These performance targets are quantified using component uniform hazard spectra (CUHS), which identify acceleration values that have constant mean return periods. This method is used to evaluate trends in CURS, and is compared to ASCE 7 design estimates of component seismic lateral forces. In addition, the results from this study demonstrate that ASCE 7 criteria (a) do not provide estimates of component demands with a constant reliability level, and (b) may not always provide conservative estimates of maximum lateral force demands for the design of acceleration-sensitive components in buildings

The Influence of Hip Mobility and Fatigue on Spinal Flexion and Muscle Activation in Rugby Scrum Performance

Introduction: Rugby scrumming is a means of restarting play following a minor rule infringement that can occur up to 28 times per game. The scrum poses a significant injury risk, with more days missed due to injury per event than any other rugby activity. Rugby players also have a significantly higher rate of spine injury than the general population, perhaps due to flexion in combination with high compression forces, which has been cited as the main mechanism of injury. Flexion of the spine has also been associated with poor hip mobility and quadriceps fatigue in other athletic tasks and may influence rugby scrumming similarly. Therefore, the purpose of this study was to determine if spine flexion, force output and muscle activation are influenced by 1) fatigue and 2) hip mobility in individual machine rugby scrumming. Methods: Sixteen participants with at least 4 years of rugby scrumming experience were recruited to complete the study. In the initial scrumming block, the participants completed five 5-second scrumming trials with 1-2 minutes rest in between each trial. They then performed a wall sit to fatigue and performed five more 5-second scrumming trials, this time with only 5 seconds of recovery in between each trial. The angle of each spinal region (Lumbar, Thoracic, Cervical), the muscle activation (quadriceps, lumbar and thoracic erector spinae and abdominal muscles) and the force output were all measured throughout each trial. A one-way repeated measures ANOVA was conducted (the factor being pre or post wall sit fatigue) to determine the influence of wall sit fatigue. A related samples t-test was conducted between the first and fifth trial of each block to determine the effect of repetitive scrumming, and correlations were conducted between different measures of hip mobility and the main output measures to determine the relationship with hip mobility. Results: Wall sit fatigue led to a decrease in Thoracic Erector Spinae (left: p = 0.0003, right: p \u3c 0.0001) and External Oblique (left: p = 0.0009, right: p \u3c 0.0001) activation and an increase in average (p \u3c 0.0001) and max (p \u3c 0.0001) cervical flexion during the contact phase (contact with the scrum machine shoulder pads). Prior to the wall sit, repetitive scrumming led to a decrease in activation of the Thoracic Erector Spinae (left: p = 0.0109, right: p = 0.0005) and left quadriceps (VM: p = 0.0271, VL: p = 0.0473) during the contact phase. Following the wall sit, repetitive scrumming led to a decrease in Thoracic Erector Spinae Activation (left: p = 0.0462, right: p = 0.0095), and an increase in quadriceps activation (left: VM: p = 0.0367, VL: p = 0.0419; right: VM: p = 0.0238, VL: p = 0.0213). Further, repetitive scrumming led to an increase in thoracic average (p = 0.0224) and maximum (p = 0.0058) flexion angle and an increase in cervical average (p = 0.0142) and maximum (p = 0.0048) flexion angle. It also led to an increase in Lumbar spine angle deviation (p = 0.0088) and force output deviation (p = 0.0404). Increased hip flexion range of motion was moderately related to increased impact peak force output (r = 0.55; p = 0.0290). Increased wall sit time was moderately related to increased impact peak (r = 0.52; p = 0.0376) and sustained push force (r = 0.54; p = 0.0376) for the trial prior to the wall sit. Discussion and Conclusion: It appears that fatigue, whether induced by the wall sit or by repetitive scrumming, tends to lead to a decrease in activation of the Thoracic Erector Spinae and an increase in cervical flexion. This may be due to a variety of mechanisms: a greater extension of the lower limb leading to more compensatory flexion up the kinetic chain, direct fatigue of the Thoracic Erector Spinae, central fatigue acting on the Thoracic Erector Spinae, decreased co-contraction of the trunk as a result of fatigue, and/or disuse of the cervical region during machine scrumming. This relationship needs to be explored using more rugby specific fatigue protocols, as well as in live scrumming. Surprisingly, force output was influenced very little by fatigue, indicating that the individuals were able to use compensatory mechanisms to mitigate fatigue. There also existed very little relationship between hip mobility and spine angle, likely attributable to the lack of hip range of motion used during scrumming. There did appear to be a relationship between hip flexion range of motion and impact force, which may be attributable to a greater available distance of hip acceleration with greater hip mobility, leading to a greater impact. Wall sit time was also positively related to impact peak and sustained push which may indicate a benefit to using this test as a predictive measure to determine force output capacity in an isometric movement such as the rugby scrum

Passive Thermal Storage of Small Satellites for SWaP Improvements Over Thousands of Operational Cycles

Satellite manufacturers and customers continue to trend toward higher power, duty cycle-driven components (high powered amplifiers) to get the most capability out of each small/CubeSat put in orbit. The result is more waste heat to manage, requiring engineers to develop a means of transferring or storing the energy without causing a substantial increase in thermal management system mass. Phase Change Material (PCM) heat sinks are being utilized by the industry as a solution to this challenge due to their fully passive operation and ability to reduce the mass of the thermal management system. PCM heat sinks for duty cycle applications are intended to absorb waste heat during operation, then utilize the dormant period of the orbit to fully dissipate the energy stored. This time-averaged dissipation allows the radiator panel to be designed for the average heat load rather than the peak value, resulting in significant surface area reduction in most applications. PCM heat sinks can also reduce the magnitude of temperature cycles, which can also reduce the severity of solder/bond line stresses that may accumulate as fatigue damage during cyclic operation. The construction of PCM heat sinks typically employ an aluminum enclosure with an internal conductivity enhancing (fin/foam/lattice) structure with the PCM encapsulated within. The internal conductivity-enhancing structure design of the heat sink and PCM selection must be optimized together to enable high performance, as the PCM material has relatively low thermal conductivity. Furthermore, because the PCM is chosen specifically for its material properties, it is imperative that the PCM retains these properties throughout the repeated melt/solidify cycles that it will experience during use. This is especially true for satellite and space applications where the PCM may see thousands of cycles due to orbital operational profiles. As such, designers in these markets must also focus on qualification of the design across long time periods with many cycles. Long term stability of common paraffin wax (or alkanes PCMs have been verified experimentally) through thousands of operational cycles. Two common hydrocarbon PCMs, Octadecane and Eicosane, have been subjected to over 10,000 phase change cycles and the results are presented here

Differentiating Leadership Styles and Behaviors of Teacher-Leaders

The rapidly changing landscape of education necessitates that schools build the capacity to swiftly pivot to new modalities, curriculum, and operations models. Much of the onus for positively responding to these changes falls to teacher-leaders. In many schools, teacher leaders are untrained and designated by virtue of their seniority. The authors posit that differences exist in the leadership styles and behaviors of professional educators depending on their role, status, and professional learning journey. Findings from the present study affirm the existence of some of these differences and, thus, could inform future efforts to designate and train teachers for leadership roles based off of these attributes

The Impact of CEO Turnover on Equity Volatility

A change in executive leadership is a significant event in the life of a firm. Our paper investigates a potentially significant consequence of a CEO turnover: a change in equity volatility. We develop several hypotheses about how CEO changes might affect stock price volatility, and test these hypotheses using a sample of 872 CEO changes over the 1979-1995 period. We find that volatility increases following a CEO turnover, even for the most frequent type, when a CEO leaves voluntarily and is replaced by someone from inside the firm. Our results indicate that forced turnovers, which are expected to result in large strategy changes, increase volatility more than voluntary turnovers. Outside successions, which are expected to result in a successor CEO with less certain skill in managing the firm's operations, increase volatility more than inside turnovers. We also document a greater stock-price response to earnings announcements around CEO turnover, consistent with more informative signals of value driving the increased volatility. Controls for firm-specific characteristics indicate that the volatility changes cannot be entirely attributed to factors such as changes in firm operations, firm size, and both volatility change and performance prior to the turnover

The role of paliperidone extended release for the treatment of bipolar disorder

Jehan Marino1, Clayton English2, Joshua Caballero1, Catherine Harrington11College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL, 2College of Pharmacy, Albany College of Pharmacy and Health Sciences, Colchester, VT, USABackground: Bipolar disorder (BD) is a chronic, relapsing, episodic mental illness associated with other psychiatric comorbidities. There is a substantial economic burden with BD, which makes it challenging to treat. The aim of this review is to evaluate the pharmacology, clinical efficacy, and safety data related to paliperidone extended release (ER) for the treatment of BD.Methods: A literature search was performed from January 1966 through January 2012 using PreMEDLINE, MEDLINE, EMBASE, IPA, and ClinicalTrials.gov to identify articles in English regarding the pharmacology, clinical efficacy, and safety of paliperidone ER in acute mania or mixed episodes or in the maintenance treatment of BD I.Results: There are currently three published studies relating to the use of paliperidone ER for the treatment of BD. Two of these evaluated paliperidone ER as monotherapy for acute mania, while the other assessed its role as adjunct with a mood stabilizer.Conclusion: According to the limited available evidence, paliperidone at higher doses of ER 9–12 mg/day may be a safe and efficacious treatment option for acute episodes of mania in BD. A once-daily dose formulation may improve patient adherence to treatment; however, the cost of paliperidone ER, which is higher than that of generically available second-generation antipsychotics (such as olanzapine and risperidone), and a lack of alternative dosage forms (ie, liquid, intramuscular) compared with other agents may limit its usefulness in the treatment of BD. The role of paliperidone ER as an adjunctive agent or for long-term use requires further investigation.Keywords: paliperidone ER, bipolar disorder, clinical efficacy, safet

Helicobacter pylori infection is associated with an increased rate of diabetes.

ObjectiveChronic infections could be contributing to the socioeconomic gradient in chronic diseases. Although chronic infections have been associated with increased levels of inflammatory cytokines and cardiovascular disease, there is limited evidence on how infections affect risk of diabetes.Research design and methodsWe examined the association between serological evidence of chronic viral and bacterial infections and incident diabetes in a prospective cohort of Latino elderly. We analyzed data on 782 individuals aged >60 years and diabetes-free in 1998-1999, whose blood was tested for antibodies to herpes simplex virus 1, varicella virus, cytomegalovirus, Helicobacter pylori, and Toxoplasma gondii and who were followed until June 2008. We used Cox proportional hazards regression to estimate the relative incidence rate of diabetes by serostatus, with adjustment for age, sex, education, cardiovascular disease, smoking, and cholesterol levels.ResultsIndividuals seropositive for herpes simplex virus 1, varicella virus, cytomegalovirus, and T. gondii did not show an increased rate of diabetes, whereas those who were seropositive for H. pylori at enrollment were 2.7 times more likely at any given time to develop diabetes than seronegative individuals (hazard ratio 2.69 [95% CI 1.10-6.60]). Controlling for insulin resistance, C-reactive protein and interleukin-6 did not attenuate the effect of H. pylori infection.ConclusionsWe demonstrated for the first time that H. pylori infection leads to an increased rate of incident diabetes in a prospective cohort study. Our findings implicate a potential role for antibiotic and gastrointestinal treatment in preventing diabetes

Social and Psychological Factors Associated with Health Care Transition for Young Adults Living with Sickle Cell Disease

Introduction: Due to advances in disease management, mortality rates in children with sickle cell disease (SCD) have decreased. However, mortality rates for young adults (YA) increased, and understanding of social and psychological factors is critical. The aim of this study was to explore factors associated with health care transition experiences for YA with SCD. Method: This was a qualitative descriptive study. A 45-minute semistructured interview was conducted with 13 YA (M = 21.5 years, SD = 1.73). Results: Results suggest that social and psychological factors and self-management experiences influence health care transition. Eight themes emerged: “need for accessible support”; “early assistance with goal setting”; “incongruence among expectations, experiences, and preparation”; “spiritual distress”; “stigma”; “need for collaboration”; “appreciation for caring providers”; and “feeling isolated.” Discussion: Consideration of cultural contexts will guide nurses in supporting health care transition. Designing culturally relevant interventions that address unique needs for YA living with SCD is warranted