Campus-Based Agriculture: The Future of Food at Gettysburg College

This research investigates various methods for producing food on the campus of Gettysburg College in order to improve food sustainability. The transportation of food contributes to the increased use of fossil fuels, which in turn leads to global warming and climate change. By producing a larger portion of its food on-campus, Gettysburg College could reduce the amount of food transported to the school, thereby lessening the College’s environmental impact. Urban farming techniques, hydroponics, aquaponics, and greenhouse-based agriculture are explored as viable methods for achieving this goal. Examples of the use of these techniques on college campuses are drawn from Allegheny College, Acadia University, and Cornell University, among others. Possible strategies for Gettysburg College’s implementation of the farming techniques proposed in this research are also included throughout

A biomimetic basis for auditory processing and the perception of natural sounds

Biomimicry is a powerful science that aims to take advantage of nature's remarkable ability to devise innovative solutions to challenging problems. In the setting of hearing, mimicking how humans hear is the foremost strategy in designing effective artificial hearing approaches. In this work, we explore the mathematical foundations for the exchange of design inspiration and features between biological hearing systems, artificial sound-filtering devices, and signal processing algorithms. Our starting point is a concise asymptotic analysis of subwavelength acoustic metamaterials. We are able to fine tune this structure to mimic the biomechanical properties of the cochlea, at the same scale. We then turn our attention to developing a biomimetic signal processing algorithm. We use the response of the cochlea-like structure as an initial filtering layer and then add additional biomimetic processing stages, designed to mimic the human auditory system's ability to recognise the global properties of natural sounds

A New Species of \u3ci\u3eHydrochara\u3c/i\u3e (Coleoptera: Hydrophilidae) from the Western Great Lakes Region

A new species Hydrochara simula (Coleoptera: Hydrophilidae) is described from Wis- consin and separated from other western Great Lakes species by a key. It is similar to H. obtusata (Say) and H. soror Smetana, but males can be easily recognized by a dorso-basal concavity of the aedeagus. Females can be distinguished from H. obtusata and H. soror by the more elongate penultimate segment of the maxillary palpus and other less consistent characters

PXR-mediated Metabolism During Pregnancy and Cholestasis

Nuclear receptors, including the pregnane x receptor (PXR) and the farnesoid x receptor (FXR), regulate the expression of genes that maintain bile acid (BA) homeostasis. Intrahepatic cholestasis of pregnancy (ICP) is a common gestational liver disease and BAs are implicated in its pathogenesis. Rodents exhibit maternal liver growth in order to meet the metabolic demands of pregnancy. This process is found to precede changes in body weight, occur in the presence of raised serum BAs and is likely to be driven by a placental lactogen. While the growth is normally achieved by hepatocyte hypertrophy, potentially harmful hyperplasia makes a major contribution in mice lacking Fxr. Consistent with reports of raised serum BAs in normal pregnant women, hepatic BAs are found in association with pro-cholestatic gene expression in normal pregnant mice. Gestation could be a state of reduced Fxr function because BA-fed and Fxr-/- mice do not develop raised hepatic BAs during pregnancy. Sequencing and functional assessment of PXR variants revealed that polymorphisms in this gene are unlikely to contribute to the aetiology of ICP. Surprisingly, Pxr-/- mice have enhanced hepatic metabolism and are resistant to toxicity caused by lithocholic acid (LCA). Furthermore, while hepatic Pxr is activated by intraperitoneal injection of LCA, it is not activated by physiologically relevant LCA-feeding. Summary: Pregnancy causes liver growth, raised hepatic BA and pro-cholestatic gene expression in normal mice. In humans, these adaptations may expose predisposed individuals to gestational liver disease. Genetic variation in PXR does not contribute to ICP and Pxr may play only a limited role in mediating hepatic responses to toxic BAs

On the effects of self- and cross-phase modulation on photon purity for four-wave mixing photon-pair sources

We consider the effect of self-phase modulation and cross-phase modulation on the joint spectral amplitude of photon pairs generated by spontaneous four-wave mixing. In particular, the purity of a heralded photon from a pair is considered, in the context of schemes that aim to maximise the purity and minimise correlation in the joint spectral amplitude using birefringent phase-matching and short pump pulses. We find that non-linear phase modulation effects will be detrimental, and will limit the quantum interference visibility that can be achieved at a given generation rate. An approximate expression for the joint spectral amplitude with phase modulation is found by considering the group velocity walk-off between each photon and the pump, but neglecting the group-velocity dispersion at each wavelength. The group-velocity dispersion can also be included with a numerical calculation, and it is shown that it only has a small effect on the purity for the realistic parameters considered.Comment: 11 pages, 10 figure

Control of fluid flows and other systems governed by partial differential-algebraic equations

The motion of fluids, such as air or water, is central to many engineering systems of significant economic and environmental importance. Examples range from air/fuel mixing in combustion engines to turbulence induced noise and fatigue on aircraft. Recent advances in novel sensor/actuator technologies have raised the intriguing prospect of actively sensing and manipulating the motion of the fluid within these systems, making them ripe for feedback control, provided a suitable control model exists. Unfortunately, the models for many of these systems are described by nonlinear, partial differential-algebraic equations for which few, if any, controller synthesis techniques exist. In stark contrast, the majority of established control theory assumes plant models of finite (and typically small) state dimension, expressed as a linear system of ordinary differential equations. Therefore, this thesis explores the problem of how to apply the mainstream tools of control theory to the class of systems described by partial differential-algebraic equations, that are either linear, or for which a linear approximation is valid. The problems of control system design for infinite-dimensional and algebraically constrained systems are treated separately in this thesis. With respect to the former, a new method is presented that enables the computation of a bound on the n-gap between a discretisation of a spatially distributed plant, and the plant itself, by exploiting the convergence rate of the v-gap metric between low-order models of successively finer spatial resolution. This bound informs the design, on loworder models, of H[infinity] loop-shaping controllers that are guaranteed to robustly stabilise the actual plant. An example is presented on a one-dimensional heat equation. Controller/estimator synthesis is then discussed for finite-dimensional systems containing algebraic, as well as differential equations. In the case of fluid flows, algebraic constraints typically arise from incompressibility and the application of boundary conditions. A numerical algorithm is presented, suitable for the semi-discrete linearised Navier-Stokes equations, that decouples the differential and algebraic parts of the system, enabling application of standard control theory without the need for velocity-vorticity type methods. This algorithm is demonstrated firstly on a simple electrical circuit, and secondly on the highly non-trivial problem of flow-field estimation in the transient growth region of a flat-plate boundary layer, using only wall shear measurements. These separate strands are woven together in the penultimate chapter, where a transient energy controller is designed for a channel-flow system, using wall mounted sensors and actuators