3,640 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
New Records of Eurymerodesmid Millipeds (Diplopoda: Polydesmida) from Arkansas, Kansas, Louisiana, Oklahoma, and Texas
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
Geographic Distribution Records for Scolopendromorph Centipedes (Arthropoda: Chilopoda) from Arkansas, Oklahoma, and Texas
During 2001-2003, we collected eight species of scolopendromorph centipedes from 17 counties of Arkansas (AR), seven counties of Oklahoma (OK), and 17 counties of Texas (TX). The following taxa were collected: Cryptops leucopodus (Rafinesque) from Bowie and Cass counties, TX, and Pulaski County, AR; Hemiscolopendra marginata (Say) from Columbia, Garland, Hempstead, Little River, Pike, Polk, and Yell counties, AR, and Cass, Cherokee, Coryell, Houston, Johnson, Kimble, Marion, Nacogdoches, Smith, and Tom Green counties, TX; Scolopocryptops rubiginosus L. Koch from Bowie and Dallas counties, TX; Scolopocryptops sexspinosus (Say) from Clark, Columbia, Conway, Faulkner, Hot Spring, Garland, Miller, Montgomery, Polk, Pope, and Pulaski counties, AR, LeFlore and McCurtain counties, OK, and Marion, Red River, and Rusk counties, TX; Scolopendra hews Girard from Atoka, Major, and McCurtain counties, OK; Scolopendra polymorpha Wood from Woodward County, OK; Theatops posticus (Say) from Montgomery County, AR, Choctaw, Marshall, and McCurtain counties, OK, and Cass, Dallas, Freestone, Hopkins, Houston, Red River, and Titus counties, TX; and Theatops spinicaudus (Wood) from Garland, Hot Spring, Little River, Pike, and Scott counties, AR, and Atoka, Choctaw, and McCurtain counties, OK. Most significantly, our records of S. rubiginosus are well outside its distributional range as depicted in Shelley (2002). A total of 43 new county records is documented, including 14 in Arkansas, nine in Oklahoma, and 20 in Texas
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