Wavelength selection beyond Turing

Spatial patterns arising spontaneously due to internal processes are ubiquitous in nature, varying from regular patterns of dryland vegetation to complex structures of bacterial colonies. Many of these patterns can be explained in the context of a Turing instability, where patterns emerge due to two locally interacting components that diffuse with different speeds in the medium. Turing patterns are multistable, such that many different patterns with different wavelengths are possible for the same set of parameters, but in a given region typically only one such wavelength is dominant. In the Turing instability region, random initial conditions will mostly lead to a wavelength that is similar to that of the leading eigenvector that arises from the linear stability analysis, but when venturing beyond, little is known about the pattern that will emerge. Using dryland vegetation as a case study, we use different models of drylands ecosystems to study the wavelength pattern that is selected in various scenarios beyond the Turing instability region, focusing the phenomena of localized states and repeated local disturbances

The Cancer Transition in Japan since 1951

The overall trend of cancer mortality in Japan has been decreasing since the 1960s (age-standardized death rates for ages 30-69), though trends differ enormously among various forms of the disease. Cancer mortality was heavily influenced by Japanese postwar economic recovery, which led to improved living conditions and better control of infectious agents known to cause some common forms of cancer (stomach, cervical). However, Japanese wealth and development have also been associated with risky personal behaviors (smoking, drinking) and other conditions, leading to increases in cancers with no known or else very weak links to infection. This shift away from infectious and toward non-infectious causes of prevalent forms of cancers is called the "cancer transition," by analogy to Omran's "epidemiologic transition." We suggest that the cancer transition described here in the case of Japan must be a part of efforts to revise and update the epidemiologic transition, which should incorporate new knowledge about the role of infection in chronic disease morbidity and mortality.cancer, cancer transition, epidemiologic transition, health, health and development, infectious diseases, Japan, mortality, non-infectious disease

Euler Integration of Gaussian Random Fields and Persistent Homology

In this paper we extend the notion of the Euler characteristic to persistent homology and give the relationship between the Euler integral of a function and the Euler characteristic of the function's persistent homology. We then proceed to compute the expected Euler integral of a Gaussian random field using the Gaussian kinematic formula and obtain a simple closed form expression. This results in the first explicitly computable mean of a quantitative descriptor for the persistent homology of a Gaussian random field.Comment: 21 pages, 1 figur

A History of the Biology Department

This departmental history was written on the occasion of the UND Quasquicentennial in 2008.https://commons.und.edu/departmental-histories/1030/thumbnail.jp

Efficacy of Tailwater Recovery Systems as an Approach to Water Resource Conservation

Water conservation practices are being widely implemented to alleviate sediment and nutrient losses from agricultural land and unsustainable groundwater use for irrigation. Tailwater recovery (TWR) systems are conservation practices being implemented to collect and store runoff to reduce nutrient losses and provide a source of irrigation water. This collection of research is focused on evaluating TWR systems through the following actions: 1) investigate ability to reduce solids and nutrients delivery to downstream systems, 2) compare differences in solid and nutrient concentrations in surface water samples from TWR systems to irrigation water from a TWR systems; 3) determine the potential to irrigate water containing solids and nutrients; 4) quantify a water budget for TWR systems; 5) conduct cost and benefit analyses of TWR systems; and 6) analyze economic cost to reduce solids and nutrients and to retain water. Tailwater recovery systems did not significantly reduce concentrations of solids and nutrients; however, loads of solids, P, and N were significantly reduced by 43%, 32% and 44%, respectively. Mean nutrient loads per hectare available to be recycled onto the landscape were 0.20 kg ha-1 P and 0.86 kg ha-1 N. Water budget analyses show these systems save water for irrigation but were inefficient. Net present value (NPV) and benefit cost ratios were positive and \u3e1 for producers who owned the land, but remained \u3c1 if land was rented. However, beyond improvements to irrigation infrastructure, farms with a TWR system installed lost NPV of $51 to$328 per ha. Mean total cost to reduce solids using TWR systems ranged from $0 to$0.77 per kg, P was $0.61 to$3,315.72 per kg, and N was $0.13 to$396.44 per kg. The mean total cost to save water using TWR systems ranged from $189.73 to$628.23 per ML, compared to a mean cost of groundwater of $13.99 to$36.17 per ML. Mechanistically, TWR systems retain runoff on the agricultural landscape, thereby reducing the amount of sediment and nutrients entering downstream waterbodies and provide an additional source of water for irrigation; however, more cost-effective practices exist for nutrient reduction and providing water for irrigation

Some Helminths of Itasca Park Fishes

A helminth survey was conducted\u27. on 12 species of fish taken from the waters of Itasca State Park. An abundant and varied helminth fauna was found, with 3 l parasitic forms identified to genus or species. By taxonomic groups these included, 20 trematodes, 5 cestodes, 2 acanthocephalans, and 4 nematodes. Every fish examined was parasitized, but yellow perch and rockbass possessed the greatest variety of helminths. Based on the results of this survey, several aspects of parasite life cycles, geographic distribution, and hast specificity are discussed

Argumentation and Formal Reasoning Skillsin an Argumentation-Based Guided Inquiry Course

AbstractThe development of argumentation skills and scientific reasoning abilities is examined in an introductory inquiry-based physics class. The role of competing theories teaching strategy in fostering the acquisition of argumentation and formal reasoning skills is investigated. A repeated measures MANOVA analysis shows that argumentation skills improve during instruction which includes student exercises with competing theories strategie