Fluid passage-time calculation in large Markov models

Recent developments in the analysis of large Markov models facilitate the fast approximation of transient characteristics of the underlying stochastic process. So-called fluid analysis makes it possible to consider previously intractable models whose underlying discrete state space grows exponentially as model components are added. In this work, we show how fluid approximation techniques may be used to extract passage-time measures from performance models. We focus on two types of passage measure: passage-times involving individual components; as well as passage-times which capture the time taken for a population of components to evolve. Specifically, we show that for models of sufficient scale, passage-time distributions can be well approximated by a deterministic fluid-derived passage-time measure. Where models are not of sufficient scale, we are able to generate approximate bounds for the entire cumulative distribution function of these passage-time random variables, using moment-based techniques. Finally, we show that for some passage-time measures involving individual components the cumulative distribution function can be directly approximated by fluid techniques

Insecticide and Growth Regulator Effects on the Leafminer, \u3ci\u3eLiriomyza Trifolii\u3c/i\u3e (Diptera: Agromyzidae), in Celery and Observations on Parasitism

The effects of different insecticides were compared on survival and development of the leafminer, L. trifolii, in celery in Michigan and parasitism was assessed in this non- resident population. Avermectin, thiocyclam, and cyromazine effectively controlled L. trifolii larvae or prevented successful emergence as adults. Moderate to high levels of resistance to permethrin and chlorpyrifos were present. Avermectin caused high mortality of all larval stages and no adults successfully emerged. Thiocyclam caused high mortality to all larval stages, but did not affect adult emergence from the surviving larvae. Cyromazine acted most strongly against early stage larvae before visible mines were present, caused little direct mortality of larger larvae, but prevented successful adult emergence. No parasitoids emerged from 2029 larvae collected and reared, in contrast to studies in sites where L. trifolii is a year-round resident

A comprehensive study of personal and social information use in female brown-headed cowbirds, Molothrus ater

Brood parasites face considerable cognitive challenges when locating and selecting host nests for their young. One aspect of this challenge is determining how to use different sources of information to make decisions regarding the quality of a prospective nest. Here we investigate how female-brown-headed cowbirds, Molothrus ater, use information when prospecting for nests, and then expand upon this to investigate decisions related to foraging. In chapter 1, we demonstrated female could use social information acquired from observing the nest prospecting patterns of conspecifics to influence their own patterns of nest selection. Furthermore, we found a negative relationship between a female’s accuracy at using personal information and her tendency to copy others. In chapter 2, we found the females were able to use social information in a foraging setting as well. The female’s accuracy using personal information remained consistent across nest prospecting and foraging contexts however, the relationship between accuracy and tendency to copy others drastically reversed. A follow up experiment revealed the likely possibility that the differing relationship between personal and social information use depended on the degree of conflict that existed between the two types of information. In chapter 3, we redeveloped and implemented a new RFID tracking technology allowing us to investigate how the cognitive strategies from chapters 1 and 2 translated to a naturalistic, socially complex breeding environment. We found female cowbirds who spent more time prospecting, produced a greater quantity of eggs and demonstrated high accuracy scores during chapter 1 and 2, whereas females who relied on copying others spent significantly less time prospecting and demonstrated lower laying accuracy scores. By demonstrating how individuals’ cognitive strategies relate across context and translate to a socially complex setting, we have demonstrated the importance of examining behaviour in both of these settings and our RFID tracking technology provides researchers with the framework to effectively study this in the future

LANDSAT application of remote sensing to shoreline-form analysis

There are no author-identified significant results in this report

Sources, paths, and concepts for reduction of noise in the test section of the NASA Langley 4x7m wind tunnel

NASA is investigating the feasibility of modifying the 4x7m Wind Tunnel at the Langley Research Center to make it suitable for a variety of aeroacoustic testing applications, most notably model helicopter rotors. The amount of noise reduction required to meet NASA's goal for test section background noise was determined, the predominant sources and paths causing the background noise were quantified, and trade-off studies between schemes to reduce fan noise at the source and those to attenuate the sound generated in the circuit between the sources and the test section were carried out. An extensive data base is also presented on circuit sources and paths

Features in the ion emission of Cu, Al, and C plasmas produced by ultrafast laser ablation

© 2015 AIP Publishing LLC. The bi-modal nature of charge integrated ion kinetic energy distributions, which result from ultrafast laser produced plasmas, is discussed in this paper. A negatively biased Faraday cup was used as a charge collector to measure ion distributions from three different solid targets that had been irradiated with an ultrafast laser in the fluence range 0.1-1 J/cm2. A bi-modal time of flight distribution is found for all three targets (C, Al, and Cu). In the case of the metallic targets (Al and Cu), high- and low-kinetic energy peaks exhibit quite different dependencies on laser fluence, whereas for the semi-metallic target (C), both peaks scale similarly with ultrafast laser fluence. The results are discussed within the framework of a one dimensional capacitor model resulting in ion acceleration

LANDSAT application of remote sensing to shoreline-form analysis

The author has identified the following significant results. LANDSAT imagery of the southern end of Assateague Island, Virginia, was enlarged to 1:80,000 and compared with high altitude (1:130,000) and low altitude (1:24,000) aerial photography in an attempt to quantify change in land area over a nine month period. Change in area and configuration was found with LANDSAT and low altitude photography. Change in configuration, but no change in area was found with high altitude photography. Due to tidal differences at time of image obtention and lack of baseline data, the accuracy of the LANDSAT measurements could not be determined. They were consistent with the measurements from the low altitude photography

Tapering practices of strongman athletes: Test-retest reliability study

BACKGROUND: Little is currently known about the tapering practices of strongman athletes. We have developed an Internet-based comprehensive self-report questionnaire examining the training and tapering practices of strongman athletes. OBJECTIVE: The objective of this study was to document the test-retest reliability of questions associated with the Internet-based comprehensive self-report questionnaire on the tapering practices of strongman athletes. The information will provide insight on the reliability and usefulness of the online questionnaire for use with strongman athletes. METHODS: Invitations to complete an Internet questionnaire were sent via Facebook Messenger to identified strongman athletes. The survey consisted of four main areas of inquiry, including demographics and background information, training practices, tapering, and tapering practices. Of the 454 athletes that completed the survey over the 8-week period, 130 athletes responded on Facebook Messenger indicating that they intended to complete, or had completed, the survey. These participants were asked if they could complete the online questionnaire a second time for a test-retest reliability analysis. Sixty-four athletes (mean age 33.3 years, standard deviation [SD] 7.7; mean height 178.2 cm, SD 11.0; mean body mass 103.7 kg, SD 24.8) accepted this invitation and completed the survey for the second time after a minimum 7-day period from the date of their first completion. Agreement between athlete responses was measured using intraclass correlation coefficients (ICCs) and kappa statistics. Confidence intervals (at 95%) were reported for all measures and significance was set at P<.05. RESULTS: Test-retest reliability for demographic and training practices items were significant (P<.001) and showed excellent (ICC range=.84 to .98) and fair to almost perfect agreement (κ range=.37-.85). Moderate to excellent agreements (ICC range=.56-.84; P<.01) were observed for all tapering practice measures except for the number of days athletes started their usual taper before a strongman competition (ICC=.30). When the number of days were categorized with additional analyses, moderate reliability was observed (κ=.43; <.001). Fair to substantial agreement was observed for the majority of tapering practices measures (κrange=.38-.73; P<.001) except for how training frequency (κ=.26) and the percentage and type of resistance training performed, which changed in the taper (κ=.20). Good to excellent agreement (ICC=.62-.93; P<.05) was observed for items relating to strongman events and traditional exercises performed during the taper. Only the time at which the Farmer's Walk was last performed before competition showed poor reliability (ICC=.27). CONCLUSIONS: We have developed a low cost, self-reported, online retrospective questionnaire, which provided stable and reliable answers for most of the demographic, training, and tapering practice questions. The results of this study support the inferences drawn from the Tapering Practices of Strongman Athletes Stud