Longitudinal dispersion in vegetated flow

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.Includes bibliographical references (p. 171-183).Vegetation is ubiquitous in rivers, estuaries and wetlands, strongly influencing both water conveyance and mass transport. The plant canopy affects both mean and turbulent flow structure, and thus both advection and dispersion. Accurate prediction of the fate and transport of nutrients, microbes, dissolved oxygen and other scalars depends on our ability to quantify vegetative impacts. In this thesis, the focus is on longitudinal dispersion, which traditionally has been modeled by drawing analogy to rough boundary layers. This approach is inappropriate in many cases, as the vegetation provides a significant dead zone, which may trap scalars and augment dispersion. The dead zone process is not captured in the rough boundary model. This thesis describes a new theoretical model for longitudinal dispersion in a vegetated channel, which isolates three separate contributory processes. To evaluate the performance of the model, tracer experiments and velocity measurements were conducted in a laboratory flume. Results show that the mechanism of exchange between the free stream and the vegetated region is critical to the overall dispersion, and is primarily controlled by the canopy density.(cont.) A numerical random walk particle-tracking model was developed to assess the uncertainty associated with the experimental data. Results suggest that the time scale required to obtain sound experimental data in tracer studies is longer than the commonly used Fickian time scale.by Enda Murphy.S.M

The role of exercise intensity and contraction frequency in modulation of exercise response

High intensity exercise been shown to produce different acute exercise responses when compared to moderate intensity. Manipulating the rate of muscle contraction to alter intensity has received limited research. The primary purpose of this PhD was to investigate the potential mechanism that produces the acute differences observed when comparing high and moderate intensity exercise. Altering exercise intensity will be achieved through increased force and rate of contraction, as well as increased contraction rate alone. Methods In study 1, twelve recreationally active male participants completed 3 trials in random order consisting of 7x30second sprint cycles at 130%peak power output (PPO)(SIE), 60 minutes at 55% PPO (MICE), and a rest trial where no exercise was performed. In study 2 a separate nineteen recreationally active male participants cycled for 1-hr at 55% PPO at either 65-rpm or 95-rpm. In study 3 a separate eighteen recreationally active males completed a replica study similar to study 2 but with the addition of a 41minute submaximal trial at 95rpm at 55% PPO. Indirect calorimetry was used to measure a number of metabolic variables during exercise. Muscle biopsies were performed as part of study 1 and 3. Results Study 1: Significantly lower glycogen (94±24 vs 108±30 vs 125±31 mmol/kg/wt p=<.001) and increased insulin sensitivity (0.28±0.05 vs 0.25±0.04 vs 0.22±0.04 GIR p=<0.05) were observed 24 hours post SIE when compared to MICE. Study 2: Significantly greater carbohydrate utilisation (2.48±0.2 vs 1.97±0.2g/min p=<.01) was observed when exercising at 95rpm vs 65rpm at 55%PPO. Study 3: Greater total glycogen use per contraction was observed (-0.008±0.002 vs -0.006±0.002 mmol/kg/min p=<.05) at 95vs65rpm. xix Conclusions There were no fibre specific differences in glycogen use between trials. Increased glycogen use observed following SIE exercise is also observed following MICE at an increased contraction rate. The increase in glycogen use was not shown to occur as a result of increased type 2 fibre recruitment alone

Accessibility of Health Data Representations for Older Adults: Challenges and Opportunities for Design

Health data of consumer off-the-shelf wearable devices is often conveyed to users through visual data representations and analyses. However, this is not always accessible to people with disabilities or older people due to low vision, cognitive impairments or literacy issues. Due to trade-offs between aesthetics predominance or information overload, real-time user feedback may not be conveyed easily from sensor devices through visual cues like graphs and texts. These difficulties may hinder critical data understanding. Additional auditory and tactile feedback can also provide immediate and accessible cues from these wearable devices, but it is necessary to understand existing data representation limitations initially. To avoid higher cognitive and visual overload, auditory and haptic cues can be designed to complement, replace or reinforce visual cues. In this paper, we outline the challenges in existing data representation and the necessary evidence to enhance the accessibility of health information from personal sensing devices used to monitor health parameters such as blood pressure, sleep, activity, heart rate and more. By creating innovative and inclusive user feedback, users will likely want to engage and interact with new devices and their own data

Road traffic noise and cognitive function in older adults : a cross-sectional investigation of The Irish Longitudinal Study on Ageing

This research is funded under the Environmental Protection Agency (EPA) Research Programme 2014–2020.Background The World Health Organization published updated Environmental Noise Guidelines in 2018. Included are recommended limit values for environmental noise exposure based on systematic reviews for a range of health outcomes, including cognitive impairment. There is emerging evidence in the literature that chronic exposure to road traffic noise may affect cognitive function in older adults, but this relationship is not well established. This study spatially linked nationally representative health microdata from The Irish Longitudinal Study on Ageing to building-level modelled noise data for two cities in the Republic of Ireland. This was used to investigate associations between exposure to road traffic noise and cognitive function in a sample of older adults, independent of a range of socio-demographic and behavioural characteristics, as well as exposure to air pollution. Methods We used the Predictor-LimA Advanced V2019.02 software package to estimate noise originating from road traffic for the cities of Dublin and Cork in Ireland according to the new common noise assessment methodology for the European Union (CNOSSOS-EU). Noise exposure values were calculated for each building and spatially linked with geo-coded TILDA microdata for 1706 individuals aged 54 and over in the two cities. Ordinary least squares linear regression models were estimated for eight standardised cognitive tests including noise exposure as an independent variable, with standard errors clustered at the household level. Models were adjusted for individual sociodemographic, behavioural and environmental characteristics. Results We find some evidence that road traffic noise exposure is negatively associated with executive function, as measured by the Animal Naming Test, among our sample of older adults. This association appears to be accounted for by exposure to air pollution when focusing on a sub-sample. We do not find evidence of an association between noise exposure and memory or processing speed. Conclusions Long term exposure to road traffic noise may be negatively associated with executive function among older adults.Publisher PDFPeer reviewe

Road traffic noise, quality of life, and mental distress among older adults : evidence from Ireland

Funding for this research was provided by the Irish Environmental Protection Agency (EPA) Research Programme 2014–2020, which is funded by the Department of Environment, Climate and Communications in Ireland.This research contributes to an emerging evidence base that considers a possible relationship between exposure to road traffic noise and mental distress. This study aimed to determine whether chronic exposure to road traffic noise was associated with quality of life or various measures of mental distress. We spatially linked high-quality modelled noise exposure data for the cities of Dublin and Cork in Ireland to The Irish Longitudinal Study on Ageing, allowing an examination of these health outcomes among older adults while adjusting for socio-demographic and behavioural characteristics. Exposure to air pollution was also considered in the analysis, allowing any associations between noise and either quality of life or mental distress that were independent of this other stressor to be isolated. While the study did not detect evidence of an association between noise exposure and depression, anxiety, stress, or worry, it identified a negative association between exposure to road traffic noise and quality of life that was independent of a range of socio-demographic and behavioural factors. Moving from the highest quintile of noise exposure to the lowest was associated with an increase on the CASP-12 quality of life scale of 1.08 of a standard deviation.Publisher PDFPeer reviewe

Featured graphic. visualizing the minimum solution of the transportation problem of linear programming (TPLP) for beijing’s bus commuters

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Environmental Noise Mapping with Smartphone Applications: A Participatory Noise Map of West Hartford, CT

New England Noise-Con 2016: Revolution in Noise Control, Providence, Rhode Island, USA, 13-15 June 2016This paper reports on the second phase of an on-going study concerning the use of smartphone applications to measure environmental noise at the University of Hartford. This phase involved the development of two strategic noise maps of West Hartford town center: i) a standard noise map developed using traditional mapping techniques and ii) a participatory noise map utilizing smartphone-based measurement data (a citizen-science approach to noise mapping). The objective of the study was to assess the feasibility of developing a noise map using a citizen science based approach. Results suggest that smartphone applications can be used to collect environmental noise data and these data may be used in the development of a participatory noise map.Irish Research CouncilCollege of Engineering, Technology and Architecture Faculty Student Engagement Grant at the University of Hartford, USAFulbright Scholarshi

Medieval Irish Chronicles Reveal Persistent Volcanic Forcing of Severe Winter Cold Events, 431–1649 CE

Explosive volcanism resulting in stratospheric injection of sulfate aerosol is a major driver of regional to global climatic variability on interannual and longer timescales. However, much of our knowledge of the climatic impact of volcanism derives from the limited number of eruptions that have occurred in the modern period during which meteorological instrumental records are available. We present a uniquely long historical record of severe short-term cold events from Irish chronicles, 431–1649 CE, and test the association between cold event occurrence and explosive volcanism. Thirty eight (79%) of 48 volcanic events identified in the sulfate deposition record of the Greenland Ice Sheet Project 2 ice-core correspond to 37 (54%) of 69 cold events in this 1219 year period. We show this association to be statistically significant at the 99.7% confidence level, revealing both the consistency of response to explosive volcanism for Ireland's climatically sensitive Northeast Atlantic location and the large proportional contribution of volcanism to historic cold event frequencies here. Our results expose, moreover, the extent to which volcanism has impacted winter-season climate for the region, and can help to further resolve the complex spatial patterns of Northern Hemisphere winter-season cooling versus warming after major eruptions.Earth and Planetary Science

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche.

Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition