The treatment of Brazil in seven middle-grade geography textbooks

Thesis (Ed. M.)--Boston University, 195

Damping of vertical coronal loop kink oscillations through wave tunneling

The decay rate of vertical kink waves in a curved flux tube is modeled numerically. The full MHD equations are solved for a curved equilibrium flux tube in an arcade geometry and the decay of ψ, the integral over the flux tube of the modulus of the velocity perpendicular to the local magnetic field, is measured. These simulations are 2D and are thus restricted to kink oscillations in the loop plane. The decay rate is found to increase with increasing wavelength, increasing β and decreasing density contrast ratio. The wave tunneling effect is shown to be a possible mechanism for the high decay rate of the recent observed kink oscillation reported by Wang & Solanki (2004)

Analysis of a DDGS Air-Drying System with heat recovery

Dry Distiller Grains with Soluble (DDGS) are a co-product of the conversion from corn into Ethanol fuel. Several applications depend on the ability of a drying process to remove moisture from a product, such as DDGS, in an effective and economical manner. Common drying methods use air to facilitate product drying as it proficiently absorbs the unwanted moisture, creating a moist-air mixture that captures both the latent and sensible heat released from the product. The most economical approach to an Air Drying System integrates a heat recovery system that transfers the heat removed by the moist-air mixture during drying back into the drying system before rejecting the moist-air mixture out of the system. The ability to condense moisture out of the moist-air mixture represents the potential energy available for recovery in the heat recovery system. This report analyzes a DDGS Air-Drying System with Heat Recovery

Tactile Arrays for Virtual Textures

This thesis describes the development of three new tactile stimulators for active touch, i.e. devices to deliver virtual touch stimuli to the fingertip in response to exploratory movements by the user. All three stimulators are designed to provide spatiotemporal patterns of mechanical input to the skin via an array of contactors, each under individual computer control. Drive mechanisms are based on piezoelectric bimorphs in a cantilever geometry. The first of these is a 25-contactor array (5 × 5 contactors at 2 mm spacing). It is a rugged design with a compact drive system and is capable of producing strong stimuli when running from low voltage supplies. Combined with a PC mouse, it can be used for active exploration tasks. Pilot studies were performed which demonstrated that subjects could successfully use the device for discrimination of line orientation, simple shape identification and line following tasks. A 24-contactor stimulator (6 × 4 contactors at 2 mm spacing) with improved bandwidth was then developed. This features control electronics designed to transmit arbitrary waveforms to each channel (generated on-the-fly, in real time) and software for rapid development of experiments. It is built around a graphics tablet, giving high precision position capability over a large 2D workspace. Experiments using two-component stimuli (components at 40 Hz and 320 Hz) indicate that spectral balance within active stimuli is discriminable independent of overall intensity, and that the spatial variation (texture) within the target is easier to detect at 320 Hz that at 40 Hz. The third system developed (again 6 × 4 contactors at 2 mm spacing) was a lightweight modular stimulator developed for fingertip and thumb grasping tasks; furthermore it was integrated with force-feedback on each digit and a complex graphical display, forming a multi-modal Virtual Reality device for the display of virtual textiles. It is capable of broadband stimulation with real-time generated outputs derived from a physical model of the fabric surface. In an evaluation study, virtual textiles generated from physical measurements of real textiles were ranked in categories reflecting key mechanical and textural properties. The results were compared with a similar study performed on the real fabrics from which the virtual textiles had been derived. There was good agreement between the ratings of the virtual textiles and the real textiles, indicating that the virtual textiles are a good representation of the real textiles and that the system is delivering appropriate cues to the user

Effects of non-commercial thinning on Great Horned Owls on Turnbull National Wildlife Refuge

To sustain forest health, increase species diversity and reduce wildfire events in the ponderosa pine (Pinus ponderosa) forests of at Turnbull National Wildlife Refuge (TNWR) managers have implemented a variety of approaches including prescribed burning and non-commercial thinning. The impacts of thinning on owl species diversity and habitat occupancy have not been studied in these ponderosa pine forests. My study had the following objectives 1) compare forest stand metrics between treatment plots, 2) compare owl species richness between treatment plots, 3) examine if occupancy and detection patterns of Great Horned Owls varied with forest condition and season, respectively, and 4) determine how the frequency of calls and frequency of detection of calls for Great Horned Owls varied between treatments and seasons. I established three stations within three sites for each of three treatments: control (no management activity; thinned 5 years and thinned 11 years prior to study. I measured 13 habitat metrics associated with trees and ground cover at each station. I used SongMeter SM2+ digital recorders to collect owl calls in nightly sessions from 30 June 2014 to 10 August 2015. I identified 112,025 territory hoots (calls) between 27 sampling stations over 1,107 sessions using Raven Pro 1.5 spectrographs. Although there were more live trees and snags in the Control plots, the diameter at breast height did not differ between treatments. There were more stumps in the 5 year since thinning treatment. I identified only Great Horned Owl calls, although Northern Pygmy Owls, Glaucidium gnoma, were observed in areas adjacent to my treatment sites. Occupancy and detectability analysis conducted using Program Presence revealed no differences in occupancy between the control and thinned plots but detectability was least during fall and early winter. Chi square analysis of the frequency of call detections and of calls also indicated a decrease in the number of detections during fall and early winter as well as an increase in call frequency in late winter and lasting until spring. These results indicate that Great Horned Owls dominate the ponderosa pine forests of TNWR and that thinning has little impact on their use of the forests or calling behavior. Monitoring of owls in all refuge habitats over multiple years is recommended too understand species richness of owls across the entire refuge

Paleopathology at the Shady Grove Site (22QU525): A Study of Health in the Upper Yazoo Basin During the Middle Mississippian Period

The Mississippian Period (AD 1000-1539) is characterized by increasingly sedentary populations, mound building, ranked societies, and intensified agriculture. As agriculture spread throughout the Eastern Woodlands, it led to widespread health consequences, including poor nutrition and increased levels of infection. Also, environmental shifts during the Mississippian Period (AD 1000-1539) caused drier conditions, potentially leading to crop failures further exacerbating nutritional problems. This thesis focuses on the health of the Shady Grove site in the Upper Yazoo Basin, a Middle to Late Mississippian medium sized mound center where an ossuary containing up to 100 individuals was excavated in 2010. Focusing only on the adult portion of the ossuary population, health of the population was assessed using multiple childhood and nonspecific indicators of stress including stature, linear enamel hypoplasias, anemia, and periosteal reactions. Levels of specific infection such as treponemal disease, tuberculosis, and osteomyelitis were also investigated. Analysis by bone element was conducted, and long bone minimum number of individuals ranged from 32 to 39, along with 52 isolated crania. Twenty-two reconstructed individuals using long bones were analyzed to provide data to assist making intrasite comparisons between males and females at Shady Grove, and intersite comparisons with other skeletal samples in the region. Results suggest that Shady Grove was more nutritionally stressed than their counterparts. Mean stature was 159.2 cm for males and 149.04 cm for females, the shortest for both sexes among all the comparative groups. Linear enamel hypoplasia (LEH) were observed on 88% of left mandibular left canines, a rate which once again was very high among the populations in the region. Data regarding porotic hyperostosis (PH) and nonspecific infection was similar with Shady Grove showing the second highest frequency of each indicator relative to the comparative populations. Reliance on maize agriculture cannot be the only contributing factor to the high rates of nutritional stress endured by the individuals at Shady Grove, but likely these findings reflect the interplay of multiple variables including subsistence strategies, political organization and climate change. The picture that emerges provides a nuanced interpretation of the effects of Mississipianization in the Upper Yazoo Valley