Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Nutritional Sciences." Includes bibliographical references (p. 99-107).

Environmental issues are manifest throughout our lives. Sport is no exception. The concern for sustainable sport management has precipitated efforts to reduce the ecological footprint of sport, and to use sport to raise environmental awareness. This dissertation examines the challenges of reducing the ecological footprint of an urban recreational sport: disc golf. The project consists of four studies. The ecological degradation associated with the sport of disc golf is reported in the first study. It is shown that disc golf increases soil compaction, which yields greater soil erosion and a decrease in vegetation cover. The second study examines player behaviors, and identifies two behaviors that are clearly related to the environmental degradation, and that could be reduced without interfering with the game: (1) dragging bags with disc golf equipment along the ground, and (2) using tress as practice targets. The subculture of disc golfers is explored in the third study in order to identify characteristics of the subculture that could be leveraged to foster the desired behavioral changes. Disc golfers felt a strong sense of ownership and attachment to the park in which they played, and placed a high value on the sport and the park in which they played. However, disc golfers were unaware of the environmental effects of their behaviors. In the final study, a brochure was distributed to players that informed them about the environmental damage caused by dragging bags and using trees for target practice, and that appealed to their sense of ownership and attachment to the park in which they played. A multiple baseline study of disc golfer behaviors in three parks demonstrated that the brochure reduced the target behaviors so significantly that they were virtually extinguished. It is concluded that behavioral management strategies can be useful tools for environmental management of urban sport settings. It is suggested that appeals to supportive subcultural values enable self-policing of target behaviors. It is also noted that education can be an effective intervention when the values are supportive but player ignorance of their impact has allowed environmentally damaging behaviors to be tolerated. / text

This creative project consists of a short fiction film which is finished on DVD and features a full length video commentary. The video commentary is an invention of my own which utilizes an often overlooked element of DVD technology, the multi-angle ability, to effectively merge two of the most popular features of modern motion picture DVD releases: the director's commentary and the production documentary. The disk actually contains two tracks of video, each of identical length. One is the film; the other is a documentary on the making of the film, with certain sections that correspond in real time with events in the film. The user has the ability to switch between tracks at anytime for comparison. This to my knowledge has never been done before, and because of the enormous popularity of the DVD and these features, may find widespread application. This project, while only an exploration of its potential, shows that the idea has feasibility and legitimacy. / Department of Telecommunications

Doctor of Philosophy / We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionised, stratified accretion discs. The magnetic field is initially vertical and perturbations have vertical wavevectors only. Solutions are obtained at representative radial locations from the central protostar for different choices of the initial magnetic field strength, sources of ionisation, disc structure and configuration of the conductivity tensor. The MRI is active over a wide range of magnetic field strengths and fluid conditions in low conductivity discs. For the minimum-mass solar nebula model, incorporating cosmic ray and x-ray ionisation and assuming that charges are carried by ions and electrons only, perturbations grow at 1 AU for B < 8G. For a significant subset of these strengths (200mG < B < 5 G), the growth rate is of order the ideal MHD rate (0.75 Omega). Hall conductivity modifies the structure and growth rate of global unstable modes at 1 AU for all magnetic field strengths that support MRI. As a result, at this radius, modes obtained with a full conductivity tensor grow faster and are active over a more extended cross-section of the disc, than perturbations in the ambipolar diffusion limit. For relatively strong fields (e.g. B > 200 mG), ambipolar diffusion alters the envelope shapes of the unstable modes, which peak at an intermediate height, instead of being mostly flat as modes in the Hall limit are in this region of parameter space. Similarly, when cosmic rays are assumed to be excluded from the disc by the winds emitted by the magnetically active protostar, unstable modes grow at this radius for B < 2 G. For strong fields, perturbations exhibit a kink at the height where x-ray ionisation becomes active. Finally, for R = 5 AU (10 AU), unstable modes exist for B < 800 mG (B < 250 mG) and the maximum growth rate is close to the ideal-MHD rate for 20 mG < B < 500 mG (2 mG < B < 50 mG). Similarly, perturbations incorporating Hall conductivity have a higher wavenumber and grow faster than solutions in the ambipolar diffusion limit for B < 100 mG (B < 10 mG). Unstable modes grow even at the midplane for B > 100 mG (B ~ 1 mG), but for weaker fields, a small dead region exists. When a population of 0.1 um grains is assumed to be present, perturbations grow at 10 AU for B < 10 mG. We estimate that the figure for R = 1 AU would be of order 400 mG. We conclude that, despite the low magnetic coupling, the magnetic field is dynamically important for a large range of fluid conditions and field strengths in protostellar discs. An example of such magnetic activity is the generation of MRI unstable modes, which are supported at 1 AU for field strengths up to a few gauss. Hall diffusion largely determines the structure and growth rate of these perturbations for all studied radii. At radii of order 1 AU, in particular, it is crucial to incorporate the full conductivity tensor in the analysis of this instability, and more generally, in studies of the dynamics of astrophysical discs.

Emission from X-ray binaries is variable on a wide range of timescales. On long timescales, changes in mass accretion rate drive changes in spectral state. There is also rapid variability, the power spectrum of which consists of a low frequency quasi-periodic oscillation (QPO) superimposed on a broad band noise continuum. Here I investigate a model intended to quantitatively explain the observed spectral and variability properties. I consider a truncated disc geometry whereby the inner regions of an optically thick, geometrically thin accretion disc evaporate to form an optically thin, large scale height accretion flow. The QPO is driven by Lense-Thirring precession of the entire hot flow and the broad band noise is due to fluctuations in mass accretion rate which propagate towards the central object. Mass conservation ties these two processes together, enabling me to define a model for the QPO and broad band noise which uses only one set of parameters. I am thus able fit the model to data. The accretion rate fluctuations drive fluctuations in the precession frequency, giving rise to a quasi-periodic oscillation rather than a pure periodicity. The model thus predicts recent observations which show the QPO frequency to correlate with flux on short timescales. I then investigate a more unique model prediction. As the flow precesses, the patch of the disc preferentially illuminated by the flow rotates such that a non face on observer sees a quasi-periodic shift between blue and red shift in the iron K alpha line. An observation of such an effect would constitute excellent evidence for the model.

This thesis finds that vortex instabilities are not necessarily a barrier to their potential as sites for planetesimal formation. It is challenging to build planetesimals from dust within the lifetime of a protoplanetary disc and before such bodies spiral into the central star. Collecting matter in vortices is a promising mechanism for planetesimal growth, but little is known about their stability under these conditions. We therefore aim to produce a more complete understanding of the stability of these objects. Previous work primarily focusses on 2D vortices with elliptical streamlines, which we generalise. We investigate how non?constant vorticity and density power law profiles affect stability by applying linear perturbations to equilibrium solutions. We find that non?elliptical streamlines are associated with a shearing flow inside the vortex. A ?saddle point instability? is seen for elliptical?streamline vortices with small aspect ratios and we also find that this is true in general. However, only higher aspect ratio vortices act as dust traps. For constant?density vortices with a concentrated vorticity source we find parametric instability bands at these aspect ratios. Models with a density excess show many narrow bands, though with less strongly growing modes than the constant?density solutions. This implies that dust particles attracted to a vortex core may well encounter parametric instabilities, but this does not necessarily prevent dust?trapping. We also study the stability and lifetime of vortex models with a 2D flow in three dimensions. Producing nearly?incompressible 3D models of columnar vortices, we find that weaker vortices persist for longer times in both stratified and unstratified shearing boxes, and stratification is destabilising. The long survival time for weak, elongated vortices makes it easier for processes to create and maintain the vortex. This means that vortices with a large enough aspect ratio have a good chance of surviving and trapping dust for sufficient time in order to build planetesimals.

From the main sequence onwards, stars of intermediate masses (1-8 Solar masses) eject a large portion of their mass with rates as high as 0.0001 Solar masses per year during their transition through the Asymptotical Giant Branch (AGB) stage. The outflows are shaped by the same mechanisms that shape the ejecta, which in turn appear to depart from spherical symmetry as early as the AGB stage. The ejecta are then evolving into asymmetrical structures. Stars like that are giant factories of dust, responsible for the enrichment of their surrounding Galactic medium in metals heavier than helium. Depending on their abundances during the AGB stage, the stars are either oxygen-rich or carbon-rich, and as such, the dust produced in their atmospheres is either O-rich or C-rich. The chemical composition of the ejecta, indicates the stellar chemistry at the moment of ejection. The disruption of the spherical symmetry of the mass loss can be caused by fast rotation, stellar magnetic fields or binarity, the latter being the most efficient and favourable mechanism. Such mechanisms can lead to the creation of circumstellar, equatorial, dusty structures, like discs, torii or spirals. Due to their small relative sizes, compared to their surrounding nebulae, they can be studied at best with the use of infrared interferometric techniques. We report the discovery of three such structures in sources at three different evolutionary stages, respectively, with the use of single- and multi-aperture interferometry. In the C-rich AGB star V Hya we imaged via aperture masking in the near-infrared, a complex and possibly orbiting structure, which is embedded within the star's molecular torus. Our MIDI observations in the mid-infrared have revealed, a silicate disc within the symbiotic nebula M2-9 that is currently being shaped by the central binary system within its core, and a C-rich disc-like structure in the born-again star Sakurai's Object, that is also aligned to an asymmetry found in its surrounding planetary nebula. Finally, we compare the properties of the structures found here with those found in the literature in order to establish a relation between late stellar evolution and the existence of dusty structures.

<p>The behavior of fibers suspended in a flow between two counter-rotating discs has been studied experimentally. This is inspired by the refining process in the papermaking process where cellulose fibers are ground between discs in order to change performance in the papermaking process and/or qualities of the final paper product.</p><p>To study the fiber behavior in a counter-rotating flow, an experimental set-up with two glass discs was built. A CCD-camera was used to capture images of the fibers in the flow. Image analysis based on the concept of steerable filters extracted the position and orientation of the fibers in the plane of the discs. Experiments were performed for gaps of 0.1-0.9 fiber lengths, and for equal absolute values of the angular velocities for the upper and lower disc. The aspect ratios of the fibers were 7, 14 and 28.</p><p>Depending on the angular velocity of the discs and the gap between them, the fibers were found to organize themselves in fiber trains. A fiber train is a set of fibers positioned one after another in the tangential direction with a close to constant fiber-to-fiber distance. In the fiber trains, each individual fiber is aligned in the radial direction (i.e. normal to the main direction of the train).</p><p>The experiments show that the number of fibers in a train increases as the gap between the discs decreases. Also, the distance between the fibers in a train decreases as the length of the train increases, and the results for short trains are in accordance with previous numerical results in two dimensions.Furthermore, the results of different aspect ratios imply that there are three-dimensional fiber end-effects that are important for the forming of fiber trains.</p>

Classically, fluid dynamics have been dealt with analytically because of the lack of numerical resources (Yeung, 1982). With the development of computational ability, many formulations have been developed which typically use the traditional Navier-Stokes equations along with an Eulerian grid. Today, there exists the possibility of using a moving grid (Lagrangian) along with a meshless discretization. The first issue in meshless fluid dynamics is the equations of motion. There are currently two types of Lagrangian formulations. Spherical Particle Hydrodynamics (SPH) is a method which calculates all equations of motion explicitly. The Moving Particle Semi-implicit (MPS) method uses a mathematical foundation based on SPH. However, instead of calculating all laws of motion explicitly, a fractional time step is performed to calculate pressure. A proposed method, Lagrange Implicit Fraction Step (LIFS), has been created which improves the mathematical formulations on the fluid domain. The LIFS method returns to Continuum mechanics to construct the laws of motion based on decomposing all forces of a volume. It is assumed that all forces on this volume can be linearly superposed to calculate the accelerations of each mass. The LIFS method calculates pressure from a boundary value problem with the inclusion of proper flux boundary conditions. The second issue in meshless Lagrangian dynamics is the calculation of derivatives across a domain. The Monte Carlo Integration (MCI) method uses weighted averages to calculate operators. However, the MCI method can be very inaccurate, and is not suitable for sparse grids. The Radial Basis Function (RBF) method is introduced and studied as a possibility to calculate meshless operators. The RBF method involves a solution of a system of equations to calculate interpolants. Machine expenses are shown to limit the viability of the RBF method for large domains. A new method of calculation has been created called Multi-dimensional Lagrange Interpolating Polynomials (MLIP). While Lagrange Interpolating Polynomials are essentially a one-dimensional interpolation, the use of "dimensional-cuts" and Gaussian quadratures can provide multi-dimensional interpolation. This paper is divided into three sections. The first section specifies the equations of motion. The second section provides the mathematical basis for meshless calculations. The third section evaluates the effectiveness of the meshless calculations and compares two fluiddynamic codes. / Fund number: N62271-97-G-0041. / US Navy (USN) author.

We investigate the origin of the parsec-scale radio emission from the changing-look active galactic nucleus (AGN) of Mrk 590, and examine whether the radio power has faded concurrently with the dramatic decrease in accretion rates observed between the 1990s and the present. We detect a compact core at 1.6 and 8.4 GHz using new Very Long Baseline Array observations, finding no significant extended, jet-like features down to similar to 1 pc scales. The flat spectral index (alpha(8.4)(1.6) = 0.03) and high brightness temperature (T-b similar to 10(8) K) indicate self-absorbed synchrotron emission from the AGN. The radio to X-ray luminosity ratio of log(L-R/L-X) similar to -5, similar to that in coronally active stars, suggests emission from magnetized coronal winds, although unresolved radio jets are also consistent with the data. Comparing new Karl G. Jansky Very Large Array measurements with archival and published radio flux densities, we find 46 per cent, 34 per cent, and (insignificantly) 13 per cent flux density decreases between the 1990s and the year 2015 at 1.4 GHz, 5 GHz and 8.4 GHz, respectively. This trend, possibly due to the expansion and fading of internal shocks within the radio-emitting outflow after a recent outburst, is consistent with the decline of the optical-UV and X-ray luminosities over the same period. Such correlated variability demonstrates the AGN accretion-outflow connection, confirming that the changing-look behaviour in Mrk 590 originates from variable accretion rates rather than dust obscuration. The present radio and X-ray luminosity correlation, consistent with low/hard state accretion, suggests that the black hole may now be accreting in a radiatively inefficient mode.