Generalizations of Ripley's K-function with Application to Space Curves

The intensity function and Ripley's K-function have been used extensively in the literature to describe the first and second moment structure of spatial point sets. This has many applications including describing the statistical structure of synaptic vesicles. Some attempts have been made to extend Ripley's K-function to curve pieces. Such an extension can be used to describe the statistical structure of muscle fibers and brain fiber tracks. In this paper, we take a computational perspective and construct new and very general variants of Ripley's K-function for curves pieces, surface patches etc. We discuss the method from [Chiu, Stoyan, Kendall, & Mecke 2013] and compare it with our generalizations theoretically, and we give examples demonstrating the difference in their ability to separate sets of curve pieces.Comment: 9 pages & 8 figure

An Exploration of the Widely Observed Mechanisms Permitting Freeze Tolerance & the Potential of Cope’s Gray Treefrog, Dryophytes chrysoscelis

Over 80% of the Earth’s surface is exposed to seasonal cold temperatures less than 5.0oC. Ectotherms implement a variety of strategies to survive seasonal, or permanent, cold exposure. Some of the most common overwintering strategies are migration, hibernation, and freeze avoiding behavior. However, freeze tolerance is a minority choice among ectotherms. This strategy permits organisms to survive between 50.0 to 70.0% of their total body water volumes frozen primarily in extracellular spaces for up to several months at a time. Freeze tolerant organisms undergo minimal supercooling of their body fluids to ensure ice formation is slow and produce a wide variety of specific proteins to control the size of ice crystals forming in the body. Freezing gives rise to severe physiological stressors which must be mitigated in order to survive freezing and thawing. While freeze tolerance is not fully understood, a growing body of evidence highlights several core tenants of this complex physiological process. When a non-freeze tolerant organism freezes, osmotic stress caused by the removal of pure water to form ice crystals in the extracellular fluid causes cells to shrink. As ice crystals thaw, water is rapidly reintroduced into the extracellular fluid causing local hypotonicity. Consequently, cells experience a rapid influx of water molecules, inducing acute cell swelling which progresses and ultimately causes cell lysis which leads to irreparable damage to an organism’s tissues and organs. Many freeze-tolerant animals combat dehydration stress by the seasonal accumulation or rapid mobilization at ice-nucleation of colligative cryoprotectants that diffuse across cell membranes through specific integral transmembrane proteins in order to limit cellular volume changes. Cope’s gray treefrog, Dryophytes chrysocelis, is a treefrog capable of freezing 65% of its total body water content for extended periods of time during harsh winter months. This treefrog is unique because it is the only known freeze-tolerant anuran which mobilizes glycerol as a cryoprotectant. Glycerol diffuses moves across cell membranes through integral transmembrane protein channels called aquaglyceroporins. This thesis presents a comprehensive literature review which focuses primarily on proposed cellular mechanisms that mitigate dehydration stress caused by the formation of pure ice crystals, as well as anoxic and oxidative stresses caused by freezing-induced ischemia and subsequent blood reperfusion during thawing. This thesis also proposes further research to elucidate vital information about the mechanisms permitting D. chrysoscelis’ freeze tolerance. Finally, the biomedical application of human organ and tissue cryopreservation is discussed, and an argument is presented that glycerol may be a superior cryoprotectant to use in future cryopreservation studies

Institutional Effectiveness in an Open System: A Case Study of Graduation Rates in the Montana University System

This is a mixed-methods, non-experimental, cross-case study designed to examine the environmental conditions that influence institutional effectiveness within one state-governed university system. The purpose of the study was to examine nationally defined graduation rates as a performance indicator of institutional effectiveness. Eleven delimited campuses in the Montana University System constituted the sample population. The quantitative analysis compared federally mandated graduation rates with graduation rates resulting from a modified graduation rate methodology. The qualitative analysis evaluated environmental conditions at each of the institutions. The cross-case analysis synthesized the quantitative and qualitative data using an open-systems framework to identify emergent patterns. Three questions guided the research: (a) How can open-system theory inform practice in evaluating effectiveness of postsecondary institutions?, (b) How do graduation rates for all students vary within one state-governed postsecondary education system, and (c) How do environmental conditions of a specific institution explain graduation rates within one state-governed postsecondary system? This study is significant because it expands the definition of who gets included in graduation rate calculations, it utilizes state-level student-unit-records data to measure disaggregated at-risk student group performance, it evaluates how graduation rates are influenced by unique environmental conditions at individual institutions, and it contributes to a national discussion regarding postsecondary productivity. Findings of the study include: (a) graduation rates were variable among institutions, (b) institutions with higher percentages of at-risk students had lower graduation rates, (c) no single identified at-risk student group consistently performed better or worse than other student groups, (d) no two institutions had the same characteristics, and (e) graduation rates by themselves did not account for differences between institutions. In conclusion, policymakers are reminded that evaluation of institutional effectiveness requires disciplined examination of interrelations and patterns within a larger open system. Graduation rates do not account for variable environmental conditions and they do not provide an adequate measure of institutional productivity, performance, or effectiveness

Effects of auditory and visual distracters on acceptable background noise level in hearing-impaired listeners

Acceptable Noise Level (ANL), is an established procedure for determining the amount of background noise a listener is willing to accept while listening to speech. ANL is established by having the listener select most amount of background noise they are willing to accept while listening to a speech stimulus presented at their most comfortable listening level (MCL). While ANLs have been established as good predictors of hearing aid use, little is known on how hearing aid users accept background noise while engaged in cognitively demanding tasks. Previous research in normal hearing listeners has demonstrated that listeners will allow the most background noise while engaged in a visual cognitive task. While it is apparent that cognitive distracters influence acceptable background noise levels in normal hearing listeners, it is unknown if this trend is present in hearing-impaired listeners. Therefore, the goal of this study is to investigate the effects of auditory and visual distracters on acceptable BNL. Acceptable BNL levels were obtained on thirteen hearing-impaired listeners in four conditions – baseline (no distraction), visual, auditory, and competing auditory-visual distraction. Results were similar to those reported with a normal hearing population, and indicated that hearing-impaired listeners were willing to accept the most background noise with visual distraction alone

Creation and characterization of vortex clusters in atomic Bose-Einstein condensates

We show that a moving obstacle, in the form of an elongated paddle, can create vortices that are dispersed, or induce clusters of like-signed vortices in 2D Bose-Einstein condensates. We propose new statistical measures of clustering based on Ripley's K-function which are suitable to the small size and small number of vortices in atomic condensates, which lack the huge number of length scales excited in larger classical and quantum turbulent fluid systems. The evolution and decay of clustering is analyzed using these measures. Experimentally it should prove possible to create such an obstacle by a laser beam and a moving optical mask. The theoretical techniques we present are accessible to experimentalists and extend the current methods available to induce 2D quantum turbulence in Bose-Einstein condensates.Comment: 9 pages, 9 figure

Likelihood informed dimension reduction for inverse problems in remote sensing of atmospheric constituent profiles

We use likelihood informed dimension reduction (LIS) (T. Cui et al. 2014) for inverting vertical profile information of atmospheric methane from ground based Fourier transform infrared (FTIR) measurements at Sodankyl\"a, Northern Finland. The measurements belong to the word wide TCCON network for greenhouse gas measurements and, in addition to providing accurate greenhouse gas measurements, they are important for validating satellite observations. LIS allows construction of an efficient Markov chain Monte Carlo sampling algorithm that explores only a reduced dimensional space but still produces a good approximation of the original full dimensional Bayesian posterior distribution. This in effect makes the statistical estimation problem independent of the discretization of the inverse problem. In addition, we compare LIS to a dimension reduction method based on prior covariance matrix truncation used earlier (S. Tukiainen et al. 2016)

Effects of Season of Burning on the Microenvironment of Fescue Prairie in Central Saskatchewan

The microenvironmental effects of spring, summer and autumn burns were investigated for a small area of fescue prairie in Saskatchewan over two growing seasons. Maximum fire temperature in all burns exceeded 300°C at a height of 5-10 cm in the canopy. At a depth of 1 cm in the soil, temperature increased to 40°C during the summer burn, but was unaffected by burns at other seasons. Spring-burned grasses recovered to the same height as the unburned control plot by the end of the first summer. Grass height was similar in all plots by the end of the second growing season, but aboveground biomass in all burned plots was about half that of the control. Graminoid leaf area index at the end of the second growing season ranged from 0.65 in the control plot to 0.27 in the autumn burn. Surface albedos dropped to about 0.03 immediately after burning and took about 3 months to return to the pre-burn values near 0.20. By mid-June of the second year, albedos were similar in all plots. Soil temperatures at 50 cm depth in the burned plots were higher than in the control during the first summer and lower during the winter. The greatest winter snowpack (73 mm water equivalent) accumulated in the control, compared to 48, 35 and 25 mm in the spring, summer and autumn burned plots, respectively. In the first growing season the greatest demand for water occurred in the spring plot followed by the summer, control and autumn plots. In the second season water demand did not differ significantly among plots, reflecting the similarities in plant cover. The microenvironmental effects of a single burning episode in fescue prairie disappear rather quickly, so that there is little long-term impact on the vegetation

Differential regulation of different human papilloma virus variants by the POU family transcription factor Brn-3a

The Brn-3a POU family transcription factor is over-expressed in human cervical carcinoma biopsies and is able to activate expression of the human papilloma virus type 16 (HPV-16) upstream regulatory region (URR), which drives the expression of the E6 and E7 oncoproteins. Inhibition of Brn-3a expression in human cervical cancer cells inhibits HPV gene expression and reduces cellular growth and anchorage independence in vitro as well as the ability to form tumours in vivo. Here we show that Brn-3a differentially regulates different HPV-16 variants that have previously been shown to be associated with different risks of progression to cervical carcinoma. In human cervical material Brn-3a levels correlate directly with HPV E6 levels in individuals infected with a high risk variant of HPV-16 whereas this is not the case for a low risk variant. Moreover, the URRs of high and intermediate risk variants are activated by Brn-3a in transfection assays whereas the URR of a low risk variant is not. The change of one or two bases in a low risk variant URR to their equivalent in a higher risk URR can render the URR responsive to Brn-3a and vice versa. These results help explain why the specific interplay between viral and cellular factors necessary for the progression to cervical carcinoma, only occurs in a minority of those infected with HPV-16

Effectively Conducting Field Days While Responding to Unprecedented External Restrictions

Despite external influences such as societal restrictions imposed during the 2020 COVID-19 pandemic, farmers continue to work, and needs for outreach and education have not waned. Extension professionals must continue to support these needs by using media and channels not typically employed when more traditional vehicles, such as on-site consultations and field days, are not practical or safe. The Iowa Learning Farms team from Iowa State University Outreach and Extension has developed a successful Virtual Field Day program using available online tools that can be easily adopted by other Extension organizations to facilitate outreach