Criteria used to characterize lotic salmonid habitat are often based on observed correlations between physical habitat characteristics and salmonid abundances. A focus on physical habitat features ignores other habitat components, such as an adequate supply of food that set the physiological limitations on salmonid growth and survival. This study outlines the development of a habitat assessment approach that focuses on how invertebrate food availability interacts with stream temperatures to determine salmonid growth potentials. Abundances of benthic and drifting invertebrate communities, stream temperatures, and juvenile steelhead trout (Onchorhynchus mykiss gairdneri) summer growth rates and abundances were measured within 10 distinct stream segments in central Oregon. Stream temperatures and growth rates were used as inputs for bioenergetics model simulations to produce estimates of O. mykiss summer consumption rates. Measures of invertebrates providing the best description of food availability were chosen based on their ability to explain observed variation in salmonid consumption. Much of the variation in O. mykiss consumption estimates was explained by measurements of total drift biomass along a type II predator response curve. A random effects analysis of variance (ANOVA) was used to partition variation in invertebrate abundances across spatial and temporal scales. Quantification of variation at multiple scales allowed identification of a relevant spatial scale at which to assess macroinvertebrates relevant to salmonid populations, and compare the precision associated with measures of benthic and drifting invertebrate abundances. Results suggested that spatial variation in drifting and benthic invertebrate abundances are greatest at the scale of streams. Total drift biomass and total benthic biomass were more precise at the stream and stream reach scale than drift and benthic density. The information provided by this study will be used to guide the development of sampling approaches that describe invertebrates in a manner more directly related to salmonid production.

The human eyes are always moving. Even during periods of fixation when visual information is acquired, a persistent jittering of the eyes (ocular drift) is occasionally interrupted by small rapid gaze shifts (microsaccades). Though much has been learned in the last 20 years about the perceptual roles of fixational eye movements, little is known about the consequences of their active control for fine pattern vision and depth perception. Using custom techniques for high-resolution eye-tracking and precise control of retinal stimulation, this dissertation describes three studies that investigated the consequences of controlled fixational eye movements for visual perception of fine patterns in two and three dimensions. The first study addresses whether fixational eye movements are controlled to meet the needs of a demanding visual task and their contributions to visual acuity. We show that in a standard acuity test, humans actively tune their drifts to enhance relevant spatial information and control their microsaccades to precisely place stimuli within the foveola. Together these eye movements contribute 0.15 logMAR to visual acuity, approximately two lines of an eye chart. The second study addresses the perceptual and computational impact of tuning ocular drift. We show that humans are sensitive to changes in visual flow generated by drifts of different sizes. Changes in sensitivity are fully predicted by changes in effective power of luminance modulations delivered by drift, suggesting that drift acts as a mechanism for controlling the effective contrast of the retinal stimulus. The third study addresses the impact of binocular fixational eye movements on fine depth perception. We show that these movements, specifically the opposing movements of the eyes (vergence), are beneficial for stereovision. In the absence of disparity modulations from fixational vergence, fine depth perception is significantly impaired. The research described in this dissertation advances the field in several fundamental ways by showing that (a) contrary to traditional assumptions, ocular drift is tuned to the demands of the visual task; (b) the precise spatiotemporal structure of the luminance changes from ocular drift predictably impacts visual sensitivity; and (c) stereoscopic vision is a dynamic process that uses temporal disparity modulations generated by fixational vergence. / 2024-02-02T00:00:00Z

Indiana University-Purdue University Indianapolis (IUPUI) / Ion Mobility Spectrometry (IMS) is an analytical technique for separation of charged particles in the gas phase. The history of IMS is not very old, and in this century, the IMS technique has grown rapidly in the advent of modern instruments. Among currently available ion mobility spectrometers, the DTIMS, FAIMS, TWIMS, DMA are notable. Though all the IMS systems have some uniqueness in case of particle separation and detection, however, all instruments have common shortcomings. They lack in resolution, which is independent of mobility of different charged particles and they are not able to separate bigger particles (20 120 nm) with good accuracy. The work presented here demonstrates a new concept of IMS technique at atmospheric pressure which has a resolution much higher than that of the currently available DTIMS (Drift Tube Ion Mobility Spectrometry) instruments. The unique feature of this instrument is the diffusion auto-correction. Being tunable, It can separate the wide range of particles of different diameters. The working principle of this new IMS technique is different from the typical DTIMS and to simply put, it can be considered as an inversion of commonly used technique, so termed as Inverted Drift Tube (IDT).The whole work performed here can be divided into three major phases. In the first phase, the analytical solution was derived for two new separation techniques: IPF (Intermittent push flow) and NSP (Nearly stopping potential) separations. In the next phase, simulations were done to show the accuracy of the analytical solution. An ion optics simulator software called SIMION 8.1 was used for conducting the simulation works. These simulations adopted the statistical diffusion (SDS) collision algorithm to emulate the real scenario in gas phase more precisely. In the last phase, a prototype of experimental setup was built. The experimental results were then validated by simulated results.

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Revisionskvalitet är något som diskuteras flitigt i revisionsbranschen. Historiskt finns det många fall av låg revisionskvalitet som inneburit stora konsekvenser för både revisionsbyrån, men även för intressenter till det reviderade bolaget. Två stora exempel är fallet om Prosolvia samt Enron. Gemensam nämnare i båda dessa fall är att revisionsbyrån blundat för varningsklockor inom det reviderade bolaget som sedan fört med sig stora konsekvenser när dessa händelser inte gått att dölja längre. På grund av detta har mycket av den forskning som existerar idag baserats på revisorers oförmåga att upptäcka felaktigheter som sedan på ett negativt sätt kan drabba det bolagets intressenter. Däremot finns det inte speciellt mycket forskning när det motsatta händer, att revisorer delar ut varningar till bolag som inte har det så dåligt ställt som man kan tro. Även detta kan få stora konsekvenser både för det reviderade bolaget men även dess intressenter som inte längre kan lita på verksamhetens förmåga tillfortlevnad. Därför belyser den här studien problemet med revisorers utfärdande av fortsatt-drift kommentarer som sedan inte leder till en konkurs, även kallat typ-I fel. Syftet med studien var att undersöka revisionskvalitet utifrån två olika aspekter med hjälp av träffsäkerheten i revisorernas fortsatt-drift kommentarer. Först och främst syftade studien tillatt jämföra om förekomsten av typ-I fel varierade mellan olika branscher. Dessutom undersöktes huruvida förekomsten av typ-I fel ökade under Covid-19. Detta genomfördes med hjälp av en kvantitativ metod där alla fortsatt-drift kommentarer från fem givna branscher plockades ut under intervallet 2017–2020. Alltså representerade 2019-2020 Covid-19 och 2017-2018 åren innan pandemin. Datan sammanställdes genom att plocka ut information från revisionsberättelsen där det framgår om det reviderade bolaget har fått en fortsatt-drift kommentar eller inte. Vidare undersöktes om bolaget i fråga inlett en konkurs eller företagsrekonstruktion inom både 12 och 24 månader från bokslutsdagen för att kunna mäta träffsäkerheten från olika perspektiv. Resultatet visar på ett signifikant samband mellan revisionskvaliteten och bransch vad gäller träffsäkerheten för fortsatt-drift kommentarer. Däremot gick det inte att finna något samband mellan att revisionskvaliteten försämrades under Covid-19. Dock kan vi se att den totala träffsäkerheten var lägre under pandemin för de fem utvalda branscherna. Innan pandemin uppgick träffsäkerheten till 8,17% respektive 13,23% för 12 respektive 24 månader. Under pandemin uppgick siffrorna istället till 5,57% och 10,38% vilket fortfarande indikerar på att bedömningen var svårare att göra under Covid-19 kontra innan. Dessa siffror är fortfarande väldigt låga i sammanhanget och indikerar på att ökad forskning inom området är nödvändigt för att höja revisionskvaliteten överlag samt för att göra bedömningen om ett bolags förmåga till fortsatt drift mer träffsäkra och verklighetstrogna.

Tomato is a major horticulture crop grown across the globe. Unfortunately, its yield is reduced by 25% because of auxin herbicides and glyphosate drift. In this present study, wild germplasm of tomato was screened for herbicide tolerance. From the greenhouse study nine accessions for glyphosate and 2,4-D, eleven accessions for dicamba, five accessions for quinclorac, eight accessions for aminocyclopyrachlor, and two accessions for picloram and aminopyralid were identified to be tolerant. A few accessions were selected from each herbicide tolerant group for field trials at two locations in Mississippi in 2016 and 2017. Results indicated that TOM18 was most tolerant to dicamba herbicide, while TOM87 and TOM129 to glyphosate and quinclorac herbicide, respectively, on the basis of yield and injury. Molecular experiments were conducted to measure the genetic diversity among diverse germplasm. Genetic diversity analysis showed wild accessions to be highly diverse as compared to cultivated tomato.

Indiana University-Purdue University Indianapolis (IUPUI) / Tills for this study were analyzed from sites in East Antarctica (EA), West Antarctica (WA) and along a transect in the Ross Sea. Particle size, sand petrography, and detrital zircons were used to provide new information on the subglacial geology of Antarctica, as well as assisting in the reconstruction of Last Glacial Maximum (LGM) ice flow paths. Statistical analyses using the Kolmogorov-Smirnov (K-S test) reveal that EA and WA zircon age distributions are distinct at a P-value <0.05. This makes it possible to trace the unique signatures from EA and WA into the Ross Sea.

Communities are defined as the ensemble of populations that interact with each other and with the environment in a specific time and location. Community ecology studies how communities assemble, what are the patterns of diversity, abundance, and composition of species, and the processes driving these patterns. It includes four basic mechanisms for the assembly of communities: dispersal, drift, selection, and speciation, with each mechanism influencing how the communities change in a different way. Dispersal, the movement of species from one geographical location to another, plays a major role in the recolonization of barren environments and the introduction of new species to established environments. Drift (i.e., random birth and death events within a community) could, theoretically, be negligible in bacterial communities where the high population densities are expected to buffer its effect. Conversely, horizontal gene transfer can be a strong selective force, as horizontally transferred genetic material is a source of functional traits that may provide selective advantages to the recipient cells, especially in environments where strong selection pressure occurs. In my Ph.D. thesis, I aim to examine these three contrasting mechanisms in controlled, simplified bacterial communities that are designed and studied through a synthetic ecology approach. I found that even at low dispersal rates, the species abundance of planktonic bacterial communities can be homogenized by migration. This homogenization can occur even when there are strong variable selection forces interacting in each environment. I also found strong evidence on the importance of stochasticity in communities. Drift can decrease the community similarity by up to 6.3%, and increases the probabilities that species become extinct, especially in the case of rare taxa. In contrast, I found that naturally competent bacteria are favored to uptake more DNA in communities that are highly productive and phylogenetically diverse. This pattern is explained by a potential higher availability of naked DNA for naturally competent bacteria, presumably because there are more cells and the predation systems are more effective. Altogether, our findings support the theory on the importance of stochastic forces and their interaction with deterministic forces on the shaping of microbial community assembly.