Prospective Studies of Cardiovascular Risk Factors and Mild Cognitive Impairment

The association of cardiovascular risk factors including hypertension, diabetes, cholesterol, kidney function, and arterial stiffness with cognitive impairment in older adults is a well-studied phenomenon. However, there is considerably less evidence relating cardiovascular health specifically to a diagnosis of Mild Cognitive Impairment (MCI). As a precursor state of dementia, MCI is characterized by a decline in cognitive function from previous level, but not to the degree that activities of daily living are impaired. Not everyone who is diagnosed with MCI will eventually transition to dementia, but the transition rates are much higher compared to the general population (5-15% per year compared to 1-2%). The primary aim of the current investigation is to examine the relationship between individual cardiovascular risk factors and 5-year incident MCI risk and to investigate whether these relationships are moderated by apolipoprotein E genotype (APOE). An additional primary aim was to investigate whether an aggregation count of cardiovascular risk factors (MSLS-CVRFS) and two common cardiovascular risk factor profiles (FRS and ASCVD risk score) were related to 5-year incident MCI risk. Following exclusions for dementia, the study sample included 625 (Average baseline age: 61.98, 61% female) participants from the 6th and 7th waves of the Maine-Syracuse Longitudinal Study (MSLS). MCI diagnosis was made by a team of three investigators applying established MCI diagnostic criteria, with 96 participants diagnosed with possible MCI. Multiple logistic regression analysis was used to examine the association between individual baseline cardiovascular risk factors (SBP, TC, HDL, LDL, TRIG, GFR, THCY, Diabetes, PWV) and MCI with adjustment for basic demographic covariates including age, sex, years of education, and ethnicity. The same method was used for determining APOE interaction effects and relating cardiovascular risk factor scores (CVRFS, FRS, ASCVD) with MCI risk. Among individual risk factors, higher GFR and HDL were associated with lower MCI risk, while diabetes was associated with higher MCI risk. No APOE interaction effects were observed. All three of the cardiovascular risk factor scores tested were associated with higher MCI risk. These findings have clinical implications with regard to predicting MCI risk with a combination of cardiovascular risk factors. While these factors have previously been related to continuously distributed cognitive performance measures, it is critical that their relationship to a clinically defined binary outcome like MCI be investigated because treatment decisions are based on diagnosis

How do school resources and learning environments differ across Australian rural, regional and metropolitan communities

Despite recent emphasis on improved government funding and advances in technology that reduce the isolation of rural communities, research continues to highlight that Australian students attending rural schools, on average, achieve poorer academic outcomes than their urban peers. It is plausible that these lower academic outcomes are associated with the characteristics of rural schools. Little is known, however, about the nature and degree to which schools differ between rural and metropolitan communities in Australia. The aim of this study is to compare school characteristics across a range of rural and metropolitan settings, using a large-scale and nationally representative dataset. The study comprised three investigations that examined how student achievement, school resources and school learning environments vary across urban, regional, rural, and remote communities using data from the Programme for International Student Assessment (PISA). PISA is an international assessment created by the Organization for Economic Cooperation and Development (OECD) that assesses the reading, mathematics and science literacies of 15-year-old students. PISA also collects data from school principals and students about a range of student and school related variables that may be related to student literacy in the three subject domains. The three investigations used data from the 2009 cycle of PISA, which comprised approximately 470,000 students from 65 countries and economies, including over 14,000 Australian students attending 353 schools. Descriptive statistics were used to compare student and school principal perspectives about a range of school resources and learning environments. The initial paper investigated school resource variables across eight rural-urban community categories in Australia. The school resource variables included computers for education, the ratio of computers to students, computers with internet access, and principals’ perspectives of the degree to which shortages of teaching personnel and teaching materials and resources hinder student learning. On average, principals of schools in rural communities were more likely than their counterparts in larger communities to perceive that instruction was hindered by shortages of teaching personnel and to a lesser extent by shortages of teaching resources. Principals in larger towns and very large towns (ranging in size from 15,000 to 50,000 residents) reported that shortages of mathematics teachers were a hindrance to a similar degree as school principals in small rural communities. The second paper examined differences in school learning environments across eight rural-urban community categories in Australia. Learning environments were measured by the following: principals’ perceptions of teacher and student behaviour, student attitudes towards school, and student perceptions of their classroom disciplinary climate and relationships with teachers. The findings show that regardless of location, most Australian students believed that schooling is worthwhile and reported positive relationships with their teachers. However, both student and principal perceptions of disciplinary climate and learning environments were more positive in urban communities than in rural communities. The third paper compared school community differences at an international level, contrasting two economic, culturally, and socially similar nations, Canada and New Zealand, with Australia. Research focused on: average student reading performance, socioeconomic status and parent education ,principals’ perceptions about their school’s resources, and student perceptions of classroom disciplinary climate, teacher-student relations, and teacher instructional strategies. The findings showed that across Canada, New Zealand and Australia reading literacy performance and school learning environments are less positive in rural communities than in urban communities. However, these inequalities between rural and urban school communities are greater in Australia than in the other two countries. Of the three countries, rural school principals in Australia are the most likely to report that shortages of teaching personnel hinder learning. The findings show that school learning environments and school resources vary substantially across Australian school communities. Given the patterning of student performance favouring urban over rural school communities, it may very well be that elements such as rural school shortage of resources and relations between student and teacher negatively impact the academic performance of students. The three studies highlight that much still needs to be learned about: (1) recruiting and retaining teachers in large regional Australian towns; (2) the degree to which shortages of instructional material and equipment are associated with geographic location; and, (3) the reasons underlying students’ and principals’ views of school learning environments in large regional towns (up to 50,000 residence) are less positive than their counterparts’ views in rural and remote communities. The findings also suggest that education policies and structures can play a role in ameliorating or exacerbating rural educational disadvantage

An image delta compression tool: IDelta

The purpose of this thesis is to present a modified version of the algorithm used in the open source differencing tool zdelta, entitled iDelta . This algorithm will manage file data and will be built specifically to difference images in the Photoshop file format

UNDERSTANDING THE EFFICACY OF FISH LADDER USE BY ALEWIFE (ALOSA PSEUDOHARENGUS)

River herring, the collective name given to North American populations of Alewife (Alosa pseudoharengus) and Blueback Herring (A. aestivalis), are iteroparous, anadromous members of the family Clupeidae, with similar morphology, ecological roles, and overlapping distributions. Once abundant in coastal rivers of New Hampshire, many factors including commercial fishing, habitat degradation, and dam construction resulted in a precipitous decline of the species along the entire coast. Successful efforts to restore populations have included the construction of fish ladders at dams. However, fish ladders require constant operation and maintenance to efficiently pass river herring, and only provide access to spawning habitat up to the next barrier, all too often, man-made. Alewife passage efficiency in fish ladders of all designs has received little attention historically, but is important to understand how to interpret annual counts, that for many rivers are the only index used in current stock assessments. In this study, passive integrated transponder (PIT) tags were used to assess the passage efficiency of a Denil fish ladder on the Lamprey River in Newmarket, New Hampshire. The data collected allow for a better understanding of the movements and diel behavior of river herring in fishways, as well as insight into how the selectivity of fish ladders my shape the population demographics within a river system. A breached dam located at Wadleigh Falls on the Lamprey River in Lee, New Hampshire was examined to determine if river herring were able to pass the existing structure or if it should be considered the upper extent of their annual spawning migration. Telemetry data indicated that Alewives were unable to pass the breached Wadleigh Falls Dam site and that it should be considered the uppermost extent of their migratory access. Results also show that migrating fish arriving at the location had a strong preference for the river-right channel when migrating upriver and exhibited very little exploratory behavior to seek alternate pathways upriver before emigrating back downriver, approximately two weeks after river entry. These in-river residence times were very similar to those found in other telemetry studies of anadromous Alewives. Successful management and effective stock assessment for any species requires an understanding of its reproduction and recruitment. Fecundity is one measure of the reproductive potential of a species and was assessed in this study. Mature adult Alewives were collected at the head-of-tide dam on the Lamprey River in Newmarket, New Hampshire during the vernal spawning migration in 2012. A gonadosomatic index was used to determine that fish were sampled before spawning occurred, and egg diameters were quantified to examine distribution of eggs throughout the ovary. Fecundity was estimated gravimetrically using two techniques for comparison, and no difference between the methods was found. These findings show that image analysis is a fast and reliable method for fecundity estimation that does not require the use of a commonly used, toxic solution for ovary preservation. Fecundity estimates using image analysis ranged from 147,400 eggs at 24 cm to 332,500 eggs at 34 cm and aligns with previous findings of a clinal trend along the Atlantic Coast. Fecundity increased with total length, somatic weight, and age. Simple linear regressions exhibited good fits for fecundity-total length and fecundity-somatic weight, with age being the best predictor