Crossmodal Load and Selective Attention

This thesis explores a current dominant theory of attention - the load theory of selective attention and cognitive control (Lavie et al., 2004). Load theory has been posited as a potential resolution to the long-running debate over the locus of selection in attention. Numerous studies confirm that high visual perceptual load in a relevant task leads to reduced interference from task-relevant distractors; whereas high working memory load leads to increased interference from task-irrelevant distractors in a relevant task. However, very few studies have directly tested perceptual and working memory load effects on the processing of task-relevant stimuli, and even fewer studies have tested the impact of load on processing both within and between different sensory modalities. This thesis details several novel experiments that test both visual and auditory perceptual and working memory load effects on task-relevant change detection in a change-blindness “flicker” task. Results indicate that both high visual and auditory perceptual load can impact on change detection, which implies that the perceptual load model can account for load effects on change detection, both within and between different sensory modalities. Results also indicate that high visual working memory load can impact on change detection. By contrast, high auditory working memory load did not appear to impact change detection. These findings do not directly challenge load theory per-se, but instead highlight how working memory load can have markedly different effects in different experimental paradigms. The final part of this thesis explores whether high perceptual load can attenuate distraction from highly emotionally salient stimuli. The findings suggest that potent emotional stimuli can “breakthrough” and override the effects of high perceptual load - a result that presents a challenge to load theory. All findings are discussed with reference to new challenges to load theory, particularly the “dilution” argument

BUILD to WIN: Community Organizing, Power, and Participation in Local Governance

This dissertation focuses on community organizing and uses it as a mechanism to compare the political environments in Baltimore and Washington over the last three decades. By conducting comparison case studies, I identify the contextual circumstances that affect the ability of grassroots organizations to achieve desired ends. The fact that both cities have functioning Industrial Areas Foundation (IAF) affiliates - Baltimoreans United in Leadership Development (BUILD) and the Washington Interfaith Network (WIN) - provides the opportunity to investigate the conditions that give rise to community organizing. Examining the interactions between BUILD/WIN and mayoral administrations over time sheds light on the varying temporal contexts while also explicating the different managerial styles of central political actors. By conducting these case studies, I highlight the optimal political conditions for the inclusion of grassroots organizations representing the interests of neglected neighborhoods

Impementing Self-Study Review Feedback

Department Chairs who are writing a self-study or program review will benefit from this session on implementing self-study review feedback and learn how to leverage feedback to argue for new hires, additional resources for projects, and support for worthwhile initiatives

Estimates of Body Mass for Fossil Giant Ground Squirrels, Genus Paenemarmota

Paenemarmota Hibbard and Schultz, 1948 includes 3 species of giant ground squirrels within Marmotini (Rodentia, Sciuridae) from the Late Miocene and Pliocene of central and western North America. We developed skeletal and dental models for estimating body mass across modern species of Marmotini and apply these models to Paenemarmota. The most reliable models for estimating body mass of modern species (on the basis of length and width of femur, lengths of p4 and P4) generally yielded lower estimates of body mass for Paenemarmota than less reliable models (on the basis of lengths of m1, m2, M1, and M2). Models that were most reliable across modern species yielded 2 nonoverlapping estimates for P. barbouri Hibbard and Schultz, 1948: 9.59.8 kg on the basis of femur dimensions, and 14.416.2 kg on the basis of lengths of premolars. On the basis of lengths of premolars, P. mexicana (Wilson 1949) closely resembled P. barbouri in estimated mass (14.415.7 kg), but P. sawrockensis (Hibbard 1964) was smaller (10.012.4 kg). These large ground squirrels probably differed in mass-dependent biological attributes from all modern marmotines. © 2012 American Society of Mammalogists

Roadway System Assessment Using Bluetooth-Based Automatic Vehicle Identification Travel Time Data

This monograph is an exposition of several practice-ready methodologies for automatic vehicle identification (AVI) data collection systems. This includes considerations in the physical setup of the collection system as well as the interpretation of the data. An extended discussion is provided, with examples, demonstrating data techniques for converting the raw data into more concise metrics and views. Examples of statistical before-after tests are also provided. A series of case studies were presented that focus on various real-world applications, including the impact of winter weather on freeway operations, the economic benefit of traffic signal retiming, and the estimation of origin-destination matrices from travel time data. The technology used in this report is Bluetooth MAC address matching, but the concepts are extendible to other AVI data sources

Molybdenum oxide MoOₓ: a versatile hole contact for silicon solar cells

This letter examines the application of transparent MoOₓ (x < 3) films deposited by thermal evaporation directly onto crystalline silicon (c-Si) to create hole-conducting contacts for silicon solar cells. The carrier-selectivity of MoOₓ based contacts on both n- and p-type surfaces is evaluated via simultaneous consideration of the contact recombination parameter J oc and the contact resistivity ρ c. Contacts made to p-type wafers and p⁺ diffused regions achieve optimum ρ c values of 1 and 0.2 mΩ·cm², respectively, and both result in a Joc of ∼200 fA/cm². These values suggest that significant gains can be made over conventional hole contacts to p-type material. Similar MoOₓ contacts made to n-type silicon result in higher Joc and ρc with optimum values of ∼300 fA/cm² and 30 mΩ·cm² but still offer significant advantages over conventional approaches in terms of contact passivation, optical properties, and device fabrication.This project was partially funded by The Australian Renewable Energy Agency

Medium power hydrogen arcjet performance

An experimental investigation was performed to evaluate hydrogen arcjet operating characteristics in the range of 1 to 4 kW. A series of nozzles were operated in modular laboratory thrusters to examine the effects of geometric parameters such as constrictor diameter and nozzle divergence angle. Each nozzle was tested over a range of current and mass flow rates to explore stability and performance. In the range of mass flow rates and power levels tested, specific impulse values between 650 and 1250 sec were obtained at efficiencies between 30 and 40 percent. The performance of the two larger half angle (20, 15 deg) nozzles was similar for each of the two constrictor diameters tested. The nozzles with the smallest half angle (10 deg) were difiicult to operate. A restrike mode of operation was identified and described. Damage in the form of melting was observed in the constrictor region of all the nozzle inserts tested. Arcjet ignition was also difficult in many tests and a glow discharge mode that prevents starting was identified

Asymptomatic bilateral obstructing ureteric calculi resulting in Lactobacillaemia and endocarditis requiring emergency aortic valve replacement

Ureteric calculi are a common cause of emergency presentation to hospitals in the United Kingdom and worldwide. A significant and life threatening complication of those stones that obstruct the ureter is pyonephrosis, bacteraemia and resulting sepsis. Whilst the majority of such cases present with the typical symptoms of loin pain and fever, here we describe the case of a 57 year old patient with asymptomatic bilateral obstructing ureteric calculi that led to bacteraemia from a rare bacterial pathogen, Lactobacillus jensenii, and subsequent severe bacterial endocarditis requiring emergency aortic valve replacement

The Effects of Imposed Pre-Swirl on the Static and Rotordynamic Performance for Smooth Annular Liquid Seals

The tested annular seals were smooth with a length-to-diameter ratio of 0.50, a diameter of 102.0064 mm (4.016 inches), and a nominal radial clearance of 0.2032 mm (0.008 inches). The tests were conducted for angular shaft speeds, w, of 2, 4, 6, and 8 krpm, axial pressure drops, deltaP, of 2.1, 4.13, 6.21, and 8.27 bar (30, 60, 90, and 120 psi), eccentricity ratios, e0, of 0.00, 0.27, 0.53, and 0.8, with three pre-swirl inserts to target zero, medium, and high (0.0, 0.4, and 0.8) pre-swirl ratios for a set of pre-determined operating conditions with ISO VG 2 oil at 46.1°C (115°F). Circumferential fluid velocity components were measured at single locations upstream and downstream from the seal’s inlet and exit. Most of the data presented in this thesis takes place in the transitional regime. The static performance of the seals was evaluated by measuring volumetric leakage rate, Q, inlet and exit circumferential fluid velocity, and the rotor’s eccentric position. Comparisons are made between measured values and predictions. The measured vector Reynolds number ranged from approximately 1180 to approximately 4350, with only occasional points in the laminar and turbulent regimes. Pitot tubes were used to measure the average circumferential velocity at the inlet and outlet of the seal were used to calculate pre-swirl ratio, PSR, and post-swirl ratio, OSR, respectively. The PSR tended to converge to a value of approximately 0.4-0.5 as w increased for all tested pre-swirl inserts. There was little correlation between the inlet pre-swirl ratio and post-swirl ratio, OSR. This is the first known attempt to measure OSR. Rotordynamic coefficients analyzed include direct and cross-coupled: stiffness, damping, and virtual mass. The rotordynamic coefficients were generally unaffected by changing e0 E [0.00, 0.53]. When e0 = 0.80, the measured Kxx values were generally negative, while Kyy increased in magnitude by a factor of approximately 1.5 from the measured values at e0 = 0.53. The results indicated that when higher PSRs were experienced by the seal, the seal was more destabilizing. The direct damping values, Cxx and Cyy, were normally positive, and equal. When e0 = 0.80 the measured cross-coupled damping, Cxy and Cyx, decreased by a factor of 5, causing both to become negative; changing the damping from gyroscopic to dissipative. The whirl frequency ratio, WFR, indicated that the cross-coupled virtual mass terms were too small in magnitude to affect overall rotordynamic stability. WFR was generally within ~0.3-0.6 and was unaffected by changing either e0 or delta P except at w = 2 krpm. When w = 2 krpm for the zero pre-swirl insert, WFR increased in magnitude by a factor of approximately 4 when e0 increased from 0.00 to 0.80. The effective damping results showed that of the tested seals, the most stable seal configuration was w = 2 krpm for the zero pre-swirl insert particularly at high delta P’s. Both the WFR and effective damping showed that as w increases, the effect of the pre-swirl insert diminishes. For the zero pre-swirl insert, the seals were generally less stable than predicted with a few exceptions.