A comparative analysis of the Park-and-Ride/transit-oriented development tradeoff

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2008.Includes bibliographical references (p. [73]-75).Park-and-ride provided metro regions with a mechanism to reduce commute-generated vehicle-miles traveled, by capturing vehicles in or near their home communities and allowing their drivers to travel to their destinations via transit. The hypothesis underlying this study is that the loss of commuter parking to transit-oriented development involves a tradeoff of one set of benefits (and costs) for another. By assessing the performance of existing park-and-ride facilities, and comparing the associated costs and benefits with those we might expect from transit-oriented development, decision-makers might make land-use decisions that more effectively advance local and regional goals. To that end, this study sets up a methodology to allow for an "apples-to-apples" comparison of the impacts of park-and-ride and transit-oriented development on regional vehicle-miles traveled. This methodology is flexible in its methods and its application, so that it may be adapted to a range of modeling tools and techniques, available data, and regional contexts. Data collected from commuter rail stations in the Boston metro region suggests that park-and-ride performance is more a factor of station distance from commuters' destinations than of the position of a station relative to others on the transit line. This result indicates that redevelopment of park-and-ride facilities in the Boston metro region should focus on cost-inefficient facilities in communities nearer to the CBD, where the benefits of transit-oriented development are also often greater.by Jason Burgess.M.C.P

Liming Characteristics of a High-Calcium, Dry Flue Gas Desulfurization By-product and its Effects on Runoff Water Quality

In 2013, only 37% of the 32 million Mg of flue gas desulfurization (FGD) by-products generated in the United States were reused beneficially. If FGD by-products could be used as a beneficial soil amendment, millions of megagrams may be diverted away from surface impoundments and landfills. The purpose of this research was to identify the liming characteristics of a high-Ca dry FGD (DFGD) by-product in comparison to a Class-C fly ash (FA) and reagent-grade CaCO3, and to evaluate the effects of land application to a managed grassland on runoff, plant, and soil quality. Liming characteristics were determined by measuring the calcium carbonate equivalence (CCE), degree of fineness (DOF) and calculating the effective neutralizing value (ENV). The DFGD by-product was land-applied to a managed grassland in May 2015 and runoff, plant, and soil samples were collected over a 12-mo period. The ENV of 79.4% for the DFGD by-product was lower (P \u3c 0.05) than that of reagent-grade CaCO3, but similar to the ENV of commercially available liming materials. The DFGD by-product was as effective as reagent-grade CaCO3 at raising soil pH when incubated at a rate equivalent to the soil’s lime requirement and more effective than reagent-grade CaCO¬3 when incubated at 2x the soil’s lime requirement. Seasonal flow-weighted mean Ni concentrations and seasonal V loads were 44.5 and 86.9%, respectively, greater (P \u3c 0.05) when amended compared to the unamended control during at least one season. One month after application, aboveground dry matter and tissue As, Se, Cr, Co, Hg, V, and U concentrations were between 53 and 471% greater in the amended treatment than in the unamended control. Trace element concentrations decreased to pre-application levels within six months. Results demonstrated that the high-Ca DFGD by-product used in this study is a viable liming material and has minimal effects on runoff and plant quality when applied at a rate of 9 Mg ha-1. Consequently, land application of high-Ca DFGD by-products may be a viable alternative to current disposal methods

The Potential Acidification of the Mulberry River, Arkansas

The Mulberry River is a 110 km long tributary of the Arkansas River in northwest Arkansas and has been designated as a National Wild and Scenic River since 1992. In 2008, the Mulberry River was added to the 303(d) list of impaired water bodies due to the low pH of a 14.6 km segment of the river which has since increased to 68.7 km. To date, there has been little research performed on the Mulberry River and long-term routinely sampled water quality data is unavailable. The objectives of this dissertation were 1) to evaluate changes in water quality of the Mulberry River and its tributaries over a 4-year period and 2) to evaluate the relationship between forest stand type (i.e., deciduous vs coniferous) and both stream and soil chemistry. Water samples were collected monthly from 11 locations on the Mulberry River and 10 of its tributaries from March 2015 until January 2019. Soil samples were collected from 10 locations throughout the watershed with adjacent deciduous and coniferous stands. Several different tests of soil acidity indicated in no significant differences between soil from beneath the deciduous and coniferous stands. Coniferous forest land use was not correlated with stream pH (P \u3e 0.05) neither was stream pH predicted (P \u3e 0.05; R2 \u3c 0.01) by coniferous forest land use. Trend analyses indicate that there have been significant decreases in specific conductance, total suspended solids, total organic C, total N, SO4, and flow-adjusted soluble Ca and Mg and a significant increase in Cl and total Al, Fe, and Na. Out of the 21 locations sampled, only three had significant decreases in pH suggesting that the watershed has not been acidified during the duration of this study. The decrease in specific conductance and several constituents as well as the increase in streamflow and precipitation throughout Arkansas implies that the watershed has become more dilute with time. The results of this research indicate that conifer growth is not a significant source of acidity and the watershed has not become more acidic over the last 4 years

Identifying Genes Influencing the Efficiency of Photosynthesis

Photosynthesis adapts to environmental conditions over time.¹ Varying environmental conditions lead to stress accumulation on the plant.² A genetic library has been assembled for forward genetic screening of Arabidopsis thaliana.³ Arabidopsis Thaliana is a model plant used as a model organism in growth experiments. This research project aims to identify and analyze candidate genes that impact the efficiency of photosynthesis. These genes can be transplanted into commercial crops to increase efficiency of photosynthesis and crop yields

Optimising User Acceptance of Mandated Mobile Health Systems (MHS): The ePOC (Electronic Point-of-Care) Project Experience

From a clinical perspective, the use of mobile technologies such as Personal Digital Assistants (PDAs) within hospital environments is not new. A paradigm shift however, is underway towards the acceptance and utility of such systems within community-based healthcare environments. Notwithstanding, introducing new technologies and associated work practices has intrinsic risks which must be addressed. In situations where end-users of a system are traditionally averse to technology through entrenched paper-based work practices (for example, community health workers), the process of managing change bears considerable determination in system implementation success. The authors propose a novel approach to end user acceptance within the context of a mandated mobile health system in a community health setting. The ePOC (electronic point-of-care) project is used to demonstrate how higher levels of user acceptance are achievable in these implementation environments where traditionally low levels of technology acceptance and use are common

The Deuterium to Hydrogen Abundance Ratio Towards the QSO SDSS1558-0031

We present a measurement of the D/H abundance ratio in a metal-poor damped Lyman alpha (DLA) system along the sightline of QSO SDSS1558-0031. The DLA system is at redshift z = 2.70262, has a neutral column density of log(NHI)=20.67+/-0.05 cm^2, and a gas-phase metallicity [O/H]= -1.49 which indicates that deuterium astration is negligible. Deuterium absorption is observed in multiple Lyman series with a column density of log(NDI)=16.19+/-0.04 cm^2, best constrained by the deuterium Lyman-11 line. We measure log(D/H) = -4.48+/-0.06, which when combined with previous measurements along QSO sightlines gives a best estimate of log(D/H) = -4.55+/-0.04, where the 1-sigma error estimate comes from a jackknife analysis of the weighted means. Using the framework of standard big bang nucleosynthesis, this value of D/H translates into a baryon density of Omega_b h^2 = 0.0213 +/- 0.0013 +/- 0.0004 where the error terms represent the 1-sigma errors from D/H and the uncertainties in the nuclear reaction rates respectively. Combining our new measurement with previous measurements of D/H, we no longer find compelling evidence for a trend of D/H with NHI.Comment: 13 pages, 3 figures, 1 table. Accepted to the Astrophysical Journal Letter

Enhancing User Acceptance of Mandated Technology Implementation in a Mobile Healthcare Setting: A Case Study

A paradigm shift is underway towards the acceptance and utility of Personal Digital Assistant (PDA) systems within mobile-based healthcare environments. This paper contends that intervening to address user concerns as they arise throughout the system development lifecycle will lead to greater levels of user acceptance, while ultimately enhancing the deliverability of a system that provides a ‘best fit’ with end user needs. It is envisaged this research will lead to the development of a framework based on an agile approach to user acceptance measurement. The results of an ongoing study of user perceptions towards a proposed mandated electronic point-of-care (ePOC) information system in the Northern Illawarra Ambulatory Care Team (TACT) are presented

Exploring end-user perceptions towards mandated deployment of PDA-based health information systems within Ambulatory Care

The impact of many well intentioned technology integration projects has not always been viewed favourably. In fact, many projects are destined to fail from the outset by not considering fundamental IT system inves tment risks (technical failure, data failure, user failure, organizational failure) [Lyytinen & Hirschiem, 1987]. With any new technology ‘an element of uncertainty exists in the minds of decision makers with respect to the successful adoption of them’ [Bagozzi et al, 1992]. Uncertainty towards adopting new technologies is not solely the domain of decision makers. Apart from chief technology and information officers, system administrators and help desk personnel, those who ultimately feel the greatest impac t and transformation upon work practices from any newly adopted technology application or process are end-users. In mandated technology integration environments, impressions may exist whereby any form of consultative input from end-users is inherently removed, leaving end-users disillusioned with the mandated technology. This research uses an adapted version of Kline’s Groupware Adoption Scale [Kline, 2001] in a preliminary study to ascertain end-user perceptions towards the proposed mandated implementation of a PDA-based point-of-care information system (ePOC) in The Ambulatory Care Team (TACT), Northern Illawarra, South Eastern Sydney Illawarra Health Service

The Keck+Magellan Survey for Lyman Limit Absorption I: The Frequency Distribution of Super Lyman Limit Systems

We present the results of a survey for super Lyman limit systems (SLLS; defined to be absorbers with 19.0 <= log(NHI) <= 20.3 cm^-2) from a large sample of high resolution spectra acquired using the Keck and Magellan telescopes. Specifically, we present 47 new SLLS from 113 QSO sightlines. We focus on the neutral hydrogen frequency distribution f(N,X) of the SLLS and its moments, and compare these results with the Lyman-alpha forest and the damped Lyman alpha systems (DLA; absorbers with log(NHI) >= 20.3 cm^-2). We find that that f(N,X) of the SLLS can be reasonably described with a power-law of index alpha = -1.43^{+0.15}_{-0.16} or alpha = -1.19^{+0.20}_{-0.21} depending on whether we set the lower N(HI) bound for the analysis at 10^{19.0} cm^-2 or 10^{19.3}$ cm^-2, respectively. The results indicate a flattening in the slope of f(N,X) between the SLLS and DLA. We find little evidence for redshift evolution in the shape of f(N,X) for the SLLS over the redshift range of the sample 1.68 < z < 4.47 and only tentative evidence for evolution in the zeroth moment of f(N,X), the line density l_lls(X). We introduce the observable distribution function O(N,X) and its moment, which elucidates comparisons of HI absorbers from the Lyman-alpha through to the DLA. We find that a simple three parameter function can fit O(N,X) over the range 17.0 <= log(NHI) <=22.0. We use these results to predict that f(N,X) must show two additional inflections below the SLLS regime to match the observed f(N,X) distribution of the Lyman-alpha forest. Finally, we demonstrate that SLLS contribute a minor fraction (~15%) of the universe's hydrogen atoms and, therefore, an even small fraction of the mass in predominantly neutral gas.Comment: 15 pages, 10 figures, accepted to the Astrophysical Journal. Revision includes updated reference