The effects of intensive agricultural land-use practices on small streams in northwestern Iowa

Intensive agricultural land use dominates Iowa\u27s landscape, leading to degradation of the environmental quality of Iowa\u27s land, water, and biota. This study was designed to determine how land use practices affect stream environments in a typical Iowa agricultural landscape. Thirteen first order streams and their watersheds within the Northwest Iowa landform region were studied. Corn and soybeans are grown on the flat headlands of this area, while the steeper terrain is wooded or pastured. Steep erosional topography occurs in association with the Little Sioux River valley. Watershed areas ranged from 72 to 1030 hectares. Geographic Information Systems analysis was employed to categorize land use within each watershed, including that of riparian areas. Instream physical features were measured on five occasions in 1994, and stream water quality was assessed from biweekly water collections made March through October 1994, and March through September 1995.;Benthic macroinvertebrate sampling occur-red in June, August, and September 1994. Principal components analysis was used to place watersheds and streams in groups according to land use. Most watershed variation was explained by area, topography, and riparian conditions. Strong relationships existed between agricultural land use in the riparian zone, instream physical features, and water quality. From these relationships, four groups of watersheds were identified from land use patterns in the riparian zone. These groups were used to describe differences in instream physical features, water quality, and macroinvertebrate community structure. The least disturbed streams according to land use, channel morphology, and water quality possessed a high quality, but low quantity, macroinvertebrate community.;Streams with seemingly lower quality habitat, but more habitat available due to greater stream width and discharge, supported a more abundant and diverse macroinvertebrate assemblage than streams with less total but higher quality, habitat. Riparian management in these watersheds seems to be important in determining stream environmental quality based upon physical and chemical characteristics, while the amount and quality of instream physical habitat is most important in determining macroinvertebrate community structure in these headwater streams

An Investigation into How Degree of Distraction with Mobile Device Users Influences Attention to Detail

Previous research has indicated that the overuse of mobile devices by youths, especially at work or in class, can be disruptive to others, and be detrimental to the individual engaged in this activity in regards to task performance. The purpose of this study was to investigate the relationship between distraction due to use of mobile devices, while engaged in a task, and subsequent recall of details being presented during exposure to a stimulus. Due to the ubiquitous and pervasive nature of mobile devices in today\u27s youth culture, and in our society as a whole, understanding and explaining what personality types and dispositions, are likely to engage in the overuse of mobile devices, and how their motivations for acquiring and using mobile devices in the first place may potentially impact the users task performance, could possibly enlighten parents, educators, and even the subject themselves as to the causes and ramifications of such behavior; thus, paving the way to possibly developing and establishing protocols that might allow individuals to use these devices more effectively and responsibly.This investigation found that there is a significant overall inverse relationship between distraction by mobile device use while on task and attention to the details of the stimulus being presented. Persons between the ages of 26 and 40, and the personality type of Neuroticism showed some relation to being distractible. The study also found evidence that the personality type of Openness, those whose motivation for using mobile devices were utility based, and females were more likely to pay closer attention to the details of a stimulus (when controlling for all other variables including distraction by mobile device use)

Doctor of Philosophy

dissertationThis dissertation is primarily focused on the application of superresolution microscopy techniques to localization of viral proteins within envelope viruses. Advances in optical super-resolution microscopy techniques have enabled scientists to observe phenomena much smaller than the Abbe diffraction limit by stochastically limiting the number of molecules excited at a given instance and localizing their positions one at a time. Additionally, methods such as Atomic Force Microscopy (AFM) allow scientists to measure the topological features and material properties of samples through contact with a force probe. This dissertation describes the application of these two techniques to virology in order to localize internal viral proteins of enveloped virions, and measure their effect on the elastic properties of the virion. By utilizing super-resolution microscopy techniques such as Fluorescent Photo-Activated Localization Microscopy (fPALM) on virions, which have had their surface glycoproteins labeled with a photo-switchable label, the viral envelope may be accurately recovered. This dissertation describes the development and application of this technique as it applies to envelope recovery of Vesicular Stomatitis Virus (VSV) and Human Immunodeficiency Virus-1 (HIV-1). By fluorescently labeling proteins, which are internal to each of these viruses, I have been able to localize a variety of viral proteins within their recovered envelopes. This is done without significant damage to the virion, making this method a highly effective in vivo technique. In the case of VSV, an asymmetric localization along the central axis towards the blunt 5' end was found to exist for both the polymerase and phosphoproteins. These have been determined to occupy a region in the central cavity of ~57 +/-12 nm on the 5' end. This inhomogeneity of the underlying proteins such an asymmetry would predict that the Young's modulus would vary along the central axis of the virion. This dissertation also describes utilizing AFM to explore and measure the variance in young's modulus between the two distinct elastic regions observed in VSV virions, which vary by 12% in elasticity. From these combined results I have found a strong correlation between the two methodologies in order to calculate the distribution of polymerases within VSV

In vitro and in vivo activation of the pituitary-adrenal axis by corticotropin-releasing factor, vasopressin (VP), and two VP analogs

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.Not availabl

Analytical Solution of the Symmetric Circulant Tridiagonal Linear System

A circulant tridiagonal system is a special type of Toeplitz system that appears in a variety of problems in scientific computation. In this paper we give a formula for the inverse of a symmetric circulant tridiagonal matrix as a product of a circulant matrix and its transpose, and discuss the utility of this approach for solving the associated system

What's Cooler Than Being Cool? Ice-Sheet Models Using a Fluidity-Based FOSLS Approach to Nonlinear-Stokes Flow.

This research involves a few First-Order System Least Squares (FOSLS) formulations of a nonlinear-Stokes flow model for ice sheets. In Glen's flow law, a commonly used constitutive equation for ice rheology, the viscosity becomes infinite as the velocity gradients approach zero. This typically occurs near the ice surface or where there is basal sliding. The computational difficulties associated with the infinite viscosity are often overcome by an arbitrary modification of Glen's law that bounds the maximum viscosity. The FOSLS formulations developed in this thesis are designed to overcome this difficulty. The first FOSLS formulation is just the first-order representation of the standard nonlinear, full-Stokes and is known as the viscosity formulation and suffers from the problem above. To overcome the problem of infinite viscosity, two new formulation exploit the fact that the deviatoric stress, the product of viscosity and strain-rate, approaches zero as the viscosity goes to infinity. Using the deviatoric stress as the basis for a first-order system results in the the basic fluidity system. Augmenting the basic fluidity system with a curl-type equation results in the augmented fluidity system, which is more amenable to the iterative solver, Algebraic MultiGrid (AMG). A Nested Iteration (NI) Newton-FOSLS-AMG approach is used to solve the nonlinear-Stokes problems. Several test problems from the ISMIP set of benchmarks is examined to test the effectiveness of the various formulations. These test show that the viscosity based method is more expensive and less accurate. The basic fluidity system shows optimal finite-element convergence. However, there is not yet an efficient iterative solver for this type of system and this is the topic of future research. Alternatively, AMG performs better on the augmented fluidity system when using specific scaling. Unfortunately, this scaling results in reduced finite-element convergence

The motivations-attributes-skills-knowledge competency cluster validation model an empirical study

This empirical research study had two main purposes with regard to competency cluster validation. First, this empirical research study was focused upon finding the gaps in the literature that existed pertaining to the Motivations-Attributes-Skills-Knowledge Inverted Funnel Validation (MIFV) competency cluster model. The second purpose of this empirical research study was to introduce a new competency cluster validation model (MIFV). This model, if properly developed, should serve as a strong workforce development and performance measurement tool as well as a communication tool and a blueprint for success for employees. The MIFV is a sequentially upward funneling competency cluster validation model. The MIFV will provide an opportunity for the study participants to measure their efforts. In summary, the MIFV is a quantifiable model focused on workforce development and efficiencies