FHA/VA Financing and Price Discounts

This study examines the effects of FHA and VA mortgage financing on home prices. FHA and VA borrowers receive higher loan-to-value ratios (LVRs) and payment to income (PTIs) ratios relative to conventional underwriting standards. These more lenient standards are offset by the payment of additional financing costs in the form of default insurance premiums and origination fees. The hypothesis for this study is that the origination fees (in the form of insurance premiums and the funding fees) associated with FHA and VA financing will (1) be capitalized into buyer reservation values and (2) result in price discounts relative to conventional loans with lower LVRs. Using a database of nearly 9,000 homes sales in the San Antonio, TX area, we perform hedonic analyses that indicate that both types of government backed financing are associated with reductions in selling prices. The results of this study may imply a cost shifting behavior on the part of buyers and an implicit subsidy on the part of sellers. Our preferred regressions find that the price discounts for FHA underwriting are about 4% (3.81% to 4.14%) relative to conventional financing. VA discounts, as expected, are smaller, ranging from about 2% to 3.46%. Given the prior literature, we hypothesize that the results are likely a result of the fact that FHA and VA homebuyers are able to shift some costs to sellers.

Thoroughfares and Apartment Values

While the monocentric urban models were once adequate for predicting the declining rent gradients for North American cities, the advent of a transportation system with major arteries such as turnpikes, thoroughfares and commuter rails has distorted the rent gradient for many cities. In this study we examine the rent (or value) gradient for the City of Philadelphia with special reference to the impact of two major urban thoroughfares on apartment values. We find that apartment values decline by approximately 2.2% and 3.8% per block from major thoroughfares, while holding distance to the CBD and standard variables constant. As to be expected, distance to the CBD still continues to exert a dominant influence on apartment values in spite of the impacts of the thoroughfares. The findings are consistent with Ôaxial growth theory.

Tunneling calculations for GaAs-Al(x)Ga(1-x) as graded band-gap sawtooth superlattices

Quantum mechanical tunneling calculations for sawtooth (linearly graded band-gap) and step-barrier AlGaAs superlattices were performed by means of a transfer matrix method, within the effective mass approximation. The transmission coefficient and tunneling current versus applied voltage were computed for several representative structures. Particular consideration was given to effective mass variations. The tunneling properties of step and sawtooth superlattices show some qualitative similarities. Both structures exhibit resonant tunneling, however, because they deform differently under applied fields, the J-V curves differ

Sampling for Corn Flea Beetles Using Yellow Sticky Cards Placed at Different Heights and Orientations

When developing reliable disease management programs, it is important to ascertain the most reliable method to quantify the potential sources of inoculum for an epidemic. In the Stewart’s disease of corn pathosystem, the primary source of inoculum is the corn flea beetle (Chaetocnema pulicaria). This is because the transmission and survival of Pantoea stewartii, the causative organism, occurs by this vector. Management for Stewart’s disease focuses on reducing feeding by the corn flea beetle, thereby reducing transmission of the bacterium. Although there are management protocols currently in place that use visual counts for corn flea beetles to help make management decisions (i.e., insecticide spraying), it may be more practical to assess the number of corn flea beetles using yellow sticky cards. The objective of this study was to determine the optimum height and orientation for placing yellow sticky cards to sample for corn flea beetles

Master of Science

thesisWeak roof conditions in underground coal mines are a common occurrence and cause significant problems in delaying production. Thus, mine operators must look into additional support methods that reinforce the commonly used bolting, trussing, and cribbing methods. The work presented in this paper conceptualizes and models two methods of pipe umbrella roof support methods intended for employment in the underground coal mining environment. The first system is a pipe umbrella over a single entry of a development section. Secondly, a double layered pipe umbrella mesh is proposed as a reinforced roof over a longwall recovery room. Boreholes for such a configuration as the second system require precision placement and current state of the art technologies in horizontal directional drilling must be utilized. The design methodology was evaluated by examining a case study of a western U.S. coal mine and its specific geologic conditions. Geotechnical laboratory testing was performed for a weak sandstone channel material that occurs in large extents at the mine for input into numerical models. Two and three-dimensional finite difference models in Fast Lagrangian Analysis of Continua (FLAC) were developed and used as tools in the design of the pipe umbrella roof support methods proposed. One method utilizes beam elements embedded in the continuum model, while the other uses an equivalent modulus approach for modeling the reinforced zone. The effectiveness of a carefully designed pipe umbrella system is controlled by the pipe spacing, strength of the steel, and the structural geometry of the pipe. Numerical modeling of the reinforced roof shows that a reduction in recovery room closure can be achieved for the safe extraction of longwall support shields

Invasion of smooth brome into North American tall-grass prairies: impact on native plant/herbivore species and mechanisms responsible for successful invasion

Research in invasion ecology has focused on developing ecological theory that can predict how invasive species interact with invaded communities. However, empirical support for theoretical predictions has been inconsistent. Inconsistencies may be attributed to the lack of data in three core areas; (1) field data with enough resolution to determine population dynamics of invasive species in relation to native species, (2) manipulative field experiments that encapsulate natural variation found among micro-habitats, and (3) field data that incorporate effects of invasive species within and among spatial scales. This dissertation has addressed these concerns by examining the mechanisms responsible for the successful invasion and ecological impacts of the invasive grass smooth brome (Bromus inermis) within the prairies of North Dakota and Minnesota. GIS analyses revealed that native Spartina pectinata patch growth was two times greater in non-invaded areas versus areas heavily invaded with brome. The probability of extinction of native Spartina pectinata averaged 8 times more likely in areas of high versus low brome coverage. Field experiments determined differences in germination between invasive smooth brome and native prairie cordgrass were not driven by habitat differences or soil conditions. Following initial germination, invasive smooth brome had a negative impact on cordgrass establishment, which was primarily due to a 78% and 47% reduction in native cordgrass plant height and stems density, respectively. Throughout the field experiment invasive smooth brome was a dominant competitor under all habitats and soil conditions except in areas where soil salinity levels were highest. Results from the herbivore study indicated that smooth brome has the potential to have negative effects on local herbivore assemblages. Despite the large differences in herbivore species richness, diversity and evenness at our larger spatial scales, my results indicated no statistically significant effects of invasive smooth brome. Results indicated that plant species richness had a larger effect than invasive smooth brome on herbivore assemblages (i.e. plant species richness, predator abundances, landscape surroundings). Future directions for research concerning the impact of smooth brome on native herbivore assemblages should include incorporating herbivore community composition, predator abundances and landscape features (i.e. surrounding matrix, prairie isolation and management history)

Terms and Concepts for Yield, Crop Loss, and Disease Thresholds

The initial report (14) of a subcommittee of the APS Plant Disease Losses Committee dealt with terms and concepts relating to the measurement of disease intensity to obtain accurate and precise quantitative information on the relationship between disease intensity (stimulus = X) and yield or yield loss (response = Y). In addition to standardizing the terms and concepts for the measurement of disease intensity, members of the full committee identified a need to clarify and standardize terms and concepts pertaining to yield, crop loss, and disease thresholds. A second subcommittee was formed to accomplish this task. This report describes concepts concerning reference points for yield and crop loss as well as a hierarchy for threshold terms, then presents a list of terms and definitions to standardize terminology for crop loss assessment

Quantifying the Feeding Periods Required by Corn Flea Beetles to Acquire and Transmit Pantoea stewartii

The feeding periods required by corn flea beetles to acquire and transmit Pantoea stewartii were investigated in the Stewart\u27s disease of corn pathosystem. To quantify the effect of acquisition feeding period on percentage of acquisition, field-collected corn beetles were allowed to feed for 6, 12, 24 36, 48, and 72 h on corn seedlings previously inoculated with a rifampicin- and nalidixic acid-restraint strain of P. stewartii. Acquisition of P. stewartii by corn flea beetles was considered positive if the rifampicin- and nalidixic acid-marked strain was recovered on selective media. To quantity the effect of transmission feeding period on percent transmission of P. stewartii by corn flea beetles, P. stewartii- infested corn flea beetles were allowed to feed on healthy corn seedlings for periods of 3, 6, 12, 24, 36, 48, and 72 h. After the appropriate transmission feeding period, leaf tissues surrounding the sites of feeding scars were cultured for the presence of the P. stewartii-marked strain. Transmission of P. stewartii was considered positive if the marked strain was recovered on selective media. Acquisition of P. stewartii occurred within 6 h and the percentage of corn flea beetles that had acquired P. stewartii after 72 h ranged from 68 to 94%. The change in P. stewartiiacquisition by corn flea beetles (Y) with respect to acquisition feeding period (X) was best described by the Gompertz model, with R2 values ranging from 91 to 99%. The mean time for acquisition by 50% of the corn flea beetles was 36.5 ± 11.6 h. The minimum transmission feeding time required for corn flea beetles to transmit P. stewartii following a 48-h acquisition feeding period was less than 3 h. The percent transmission of P. stewartii by corn flea beetles was nearly 100% after a 48-h transmission feeding period and was 100% by 72 h. Among population growth models evaluated, the monomolecular model best described the relationship between percent transmission (Y) and transmission feeding periods (X), with R 2 values of up to 84%. However, a nonlinear form of the monomolecular model better quantified the relationship between percent transmission and transmission feeding period, because pseudo-R2 values ranged between 98.1 and 99.5%. The predicted transmission feeding time required for 50% of P. stewartii-infested corn flea beetles to transmit the pathogen was 7.6 ± 0.87 h. These results suggest that the corn flea beetle is a highly efficient vector that can quickly acquire and transmit P. stewartii, thereby requiring insecticide seed treatments and foliar insecticides that act quickly to prevent corn flea beetles from acquiring and transmitting P. stewartii to corn plants

Controlling Marangoni induced instabilities in spin-cast polymer films: how to prepare uniform films

In both research and industrial settings spin coating is extensively used to prepare highly uniform thin polymer films. However, under certain conditions, spin coating results in films with non-uniform surface morphologies. Although the spin coating process has been extensively studied, the origin of these morphologies is not fully understood and the formation of non-uniform spincast films remains a practical problem. Here we report on experiments demonstrating that the formation of surface instabilities during spin coating is dependent on temperature. Our results suggest that non-uniform spincast films form as a result of the Marangoni effect, which describes flow due to surface tension gradients. We find that both the wavelength and amplitude of the pattern increase with temperature. Finally, and most important from a practical viewpoint, the non-uniformities in the film thickness can be entirely avoided simply by lowering the spin coating temperature.Comment: 8 pages, 6 figures. electronic supplementary material: 3 pages, 4 figure

Integrating biologically rational strategies for control of anthracnose fruit rot of strawberries

Anthracnose poses a serious threat to Iowa\u27s strawberry harvest. Several biologically friendly strategies were tested for their effectiveness in controlling anthracnose and positive impacts on yields