3,690 research outputs found
The modeling of diffuse boundaries in the 2-D digital waveguide mesh
The digital waveguide mesh can be used to simulate the propagation of sound waves in an acoustic system. The accurate simulation of the acoustic characteristics of boundaries within such a system is an important part of the model. One significant property of an acoustic boundary is its diffusivity. Previous approaches to simulating diffuse boundaries in a digital waveguide mesh are effective but exhibit limitations and have not been analyzed in detail. An improved technique is presented here that simulates diffusion at boundaries and offers a high degree of control and consistency. This technique works by rotating wavefronts as they pass through a special diffusing layer adjacent to the boundary. The waves are rotated randomly according to a chosen probability function and the model is lossless. This diffusion model is analyzed in detail, and its diffusivity is quantified in the form of frequency dependent diffusion coefficients. The approach used to measuring boundary diffusion is described here in detail for the 2-D digital waveguide mesh and can readily be extended for the 3-D case
The milliped genus Euryurus Koch, 1847 (Polydesmida: Euryuridae) west of the Mississippi River; occurrence of E. leachii (Gray, 1832) on Crowleyâs Ridge, Arkansas
The milliped genus Euryurus Koch, 1847, and the species, E. leachii (Gray, 1832) (Polydesmida: Euryuridae), are recorded from three sites on the northern part of Crowleyâs Ridge (Cross, Lee, and Poinsett counties), Arkansas, where the only prior familial records are of Auturus evides (Bollman, 1887). Coupled with the published locality of E. leachii in Phillips Co., at the southern extremity of the Ridge, the only known occurrences of both the genus and species in Arkansas and west of the Mississippi River are in this physiographic feature. The Arkansas population is geographically peripheral but anatomically intermediate between the two recognized subspecies, E. l. leachii and E. l. fraternus Hoffman, 1978, and we do not assign it to a race. Molecular investigations seem necessary to resolve relationships in the âE. leachii complex.
Development and Characterization of Plasma-based Sources for Ambient Desorption/Ionization Mass Spectrometry
Thesis (Ph.D.) - Indiana University, Chemistry, 2011A number of atmospheric-pressure ionization sources for mass spectrometry has recently appeared in the literature to yield a field that is collectively referred to as Ambient Desorption/Ionization-Mass Spectrometry (ADI-MS). These sources include, among others, Desorption ElectroSpray Ionization (DESI), Direct Analysis in Real Time (DART), the Flowing Atmospheric-Pressure Afterglow (FAPA), and the Low-Temperature Plasma (LTP) probe. Collectively, these ADI-MS sources offer numerous advantages over conventional ionization sources, including direct analysis of solid, liquid, and gaseous samples, high ionization efficiency, and soft ionization. Additionally, their ability to analyze samples directly with no pretreatment dramatically reduces analysis times.
The ultimate ambient ionization source would be one that is capable of desorbing and ionizing a broad range of analytes (polar, non-polar, small molecules, biopolymers, etc.) while being minimally influenced by matrix effects. While the plasma-based ADI-MS sources, such as FAPA, DART, and LTP, have been shown to be capable of efficiently ionizing a range of small molecules, few investigations have been aimed at understanding desorption and ionization processes or matrix effects that occur with them.
At present, the performance and fundamental characteristics of the FAPA source, developed in our research group, and the LTP probe, developed at Purdue University, are being evaluated through optical and mass-spectrometric methods. The FAPA source consists of a direct-current, atmospheric-pressure glow discharge in a pin-to-plate configuration. A hole in the plate allows ionized and excited plasma species to interact directly with a sample, while physically and electrically isolating the discharge from the sample-introduction region. Conversely, the LTP probe is a high-voltage, alternating-current, dielectric-barrier discharge that interacts directly with a sample. While the fundamental processes governing these discharges are quite different, mass spectra produced with both sources are very similar. The major differences are in achievable detection limits and susceptibility to matrix effects, with the FAPA sources routinely performing better. Direct, fundamental comparisons among the FAPA source, the LTP probe, and DART are made
Using corpus linguistics to examine the extrapolation inference in the validity argument for a high-stakes speaking assessment
Investigations of the validity of a number of high-stakes language assessments are conducted using an argument-based approach, which requires evidence for inferences that are critical to score interpretation (Chapelle, Enright, & Jamieson, 2008b; Kane, 2013).
The current study investigates the extrapolation inference for a high-stakes test of spoken English, the Michigan English Language Assessment Battery (MELAB) speaking task. This inference requires evidence that supports the inferential step from observations of what test takers can do on an assessment to what they can do in the target domain (Chapelle et al., 2008b; Kane, 2013). Typically, the extrapolation inference has been supported by evidence from a criterion measure of language ability. This study proposes an additional empirical method, namely corpus-based register analysis (Biber & Conrad,
2009), which provides a quantitative framework for examining the linguistic relationship between performance assessments and the domains to which their scores are extrapolated. This approach extends Bachman and Palmerâs (2010) focus on the target language use (TLU) domain analysis in their study of assessment use arguments by providing a quantitative approach for the study of language. We first explain the connections between corpus-based register analysis and TLU analysis. Second, an investigation of the MELAB
speaking task compares the language of test-taker responses to the language of academic, professional, and conversational spoken registers, or TLU domains. Additionally, the language features at different performance levels within the MELAB speaking task are
investigated to determine the relationship between test takersâ scores and their language use in the task. Following previous studies using corpus-based register analysis, we conduct a multi-dimensional (MD) analysis for our investigation. The comparison of the language features from the MELAB with the language of TLU domains revealed that support for the extrapolation inference varies across dimensions of language use.CaMLA Spaan Research Grant Progra
Distribution of \u3ci\u3eAbacion texense\u3c/i\u3e (Loomis, 1937), the only milliped species traversing the Rio Grande, Mississippi, and Pecos rivers (Callipodida: Abacionidae)
Localities are documented for the milliped Abacion texense (Loomis, 1837) (Callipodida: Abacionidae) whose distribution forms both the northern and southern ordinal limits in the Western Hemisphere. The westernmost component of Abacion Rafinesque, 1820, A. texense is the only milliped species whose range spans the Mississippi and Pecos rivers and the Rio Grande. Distribution extremes are in Hennepin County (Co.), Minnesota, in the north; Terrell and Potter cos., Texas, in the west; Alcorn Co., Mississippi, in the east; and southwestern Tamaulipas, Mexico, in the south. Occurrences are projected for southeastern South Dakota, northwestern Alabama, and the southwestern periphery of Tennessee. The type series of A. texense consists solely of the male holotype, so a neotype will be needed if this individual is ever lost, because no paratypes were officially designated
Demographic Influences on Consumer Ethnocentrism: A Two-Study Analysis Demonstrating How Industry-Specific Personal Characteristics Impact the Occupation, Education, Marital Status, Sex and Race Dynamic
Two national surveys were conducted in the United States to test the influence of seven demographic variables on consumer ethnocentrism. Study 1 suggests a social class influence (education and occupation) on consumer ethnocentrism towards automobile brands in the United States, plus a significant relationship between marital status and consumer ethnocentrism. Study 2 tests the impact of U.S. automobile industry-specific knowledge, beliefs, and job-related behavior on ethnocentrism using similar demographic variables. Without considering industry-specific measures, occupation again significantly impacts consumer ethnocentricity among participants. However, when industry-specific measures are included, the underlying influence of gender and race on consumer ethnocentrism is revealed
Effects of tillage and poultry manure application rates on Salmonella and fecal indicator bacteria concentrations in tiles draining Des Moines Lobe soils
Application of poultry manure (PM) to cropland as fertilizer is a common practice in artificially drained regions of the Upper Midwest United States. Tile-waters have the potential to contribute pathogenic bacteria to downstream waters. This 3-year study (2010â2012) was designed to evaluate the impacts of manure management and tillage practices on bacteria losses to drainage tiles under a wide range of field conditions. PM was applied annually in spring, prior to planting corn, at application rates ranging from 5 to 40 kg/ha to achieve target rates of 112 and 224 kg/ha nitrogen (PM1 and PM2). Control plots received no manure (PM0). Each treatment was replicated on three chisel-plowed (CP) plots and one no-till (NT) plot. Tile-water grab samples were collected weekly when tiles were flowing beginning 30 days before manure application to 100 days post application, and additional grab samples were obtained to target the full spectrum of flow conditions. Manure and tile-water samples were analyzed for the pathogen,Salmonella spp. (SALM), and fecal indicator bacteria (FIB), Escherichia coli (EC), and enterococci (ENT). All three bacterial genera were detected more frequently, and at significantly higher concentrations, in tile-waters draining NT plots compared to CP plots. Transport of bacteria to NT tiles was most likely facilitated by macropores, which were significantly more numerous above tiles in NT plots in 2012 as determined by smoke-testing. While post-manure samples contained higher concentrations of bacteria than pre-manure samples, significant differences were not seen between low (PM1) and high (PM2) rates of PM application. The highest concentrations were observed under the NT PM2 plot in 2010 (6.6 Ă 103 cfu/100 mL EC, 6.6 Ă 105 cfu/100 mL ENT, and 2.8 Ă 103 cfu/100 mL SALM). Individual and 30-day geometric mean ENT concentrations correlated more strongly to SALM than EC; however, SALM were present in samples with little or no FIB
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