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Articles 1 - 10 of 10

Full-Text Articles in Life Sciences

Microbeam Methods For Assessing The Distribution Of Preservatives In Wood , Glenn M. Oren Jan 1994

Microbeam Methods For Assessing The Distribution Of Preservatives In Wood , Glenn M. Oren

Retrospective Theses and Dissertations

Compositional images constructed from characteristic x-ray signals generated within the electron microscope possess key advantages over traditional energy dispersive static probe analyses or conventional analog x-ray dot maps for assessing elemental distribution in preservative-treated wood. Digital images are produced by "stepping" the electron beam across the sample in a prescribed format and collecting x-ray information at each pixel point of the array. The various elements present are displayed on a cathode ray tube (CRT), and the peak intensities are stored on disk for subsequent processing and analysis. By assigning a different color to each element, images are produced that correspond ...


Structure Of Breeding-Bird Communities On Natural And Restored Iowa Wetlands, Julie Ann Schreiber Jan 1994

Structure Of Breeding-Bird Communities On Natural And Restored Iowa Wetlands, Julie Ann Schreiber

Retrospective Theses and Dissertations

No abstract provided.


Modelling And Evaluation Of A Cistern-Based Ground-Coupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary Jan 1994

Modelling And Evaluation Of A Cistern-Based Ground-Coupled Heat Pump: Its Implications In Reducing Energy In A Commercial Swine Operation , James D. Leary

Retrospective Theses and Dissertations

This research details the analysis of a ground-coupled heat pump system which utilizes a 20,000 gallon well-water storage tank as a source of heating and cooling. It addresses the feasibility of such a system and discusses the system in terms of energy efficiency--first law conservation analysis. The potential use of this type of system for the control of sensitive thermal environments involving swine is also evaluated;The goal of this research was to investigate ISU's SNMRC heat pump system. Specific objectives were: (1) To evaluate the system in terms of heat exchanger and heat pump efficiencies. (2) To ...


The Effects Of Fertilizers And Earthworms On Entomopathogenic Nematodes , David Ian Shapiro Jan 1994

The Effects Of Fertilizers And Earthworms On Entomopathogenic Nematodes , David Ian Shapiro

Retrospective Theses and Dissertations

Entomopathogenic nematodes in the genus Steinernema are promising biological control agents of soil insect pests. Two factors which may influence efficacy of biological control applications are virulence and dispersal of nematodes. This research examined the influence of fertilizers on the virulence of nematodes and the effects of earthworm presence on nematode dispersal;The virulence of Steinernema carpocapsae (Weiser) was determined in soil amended with fertilizer treatments of fresh cow manure, composted manure, and urea. Urea and fresh manure reduced nematode virulence in laboratory experiments. Field experiments, however, only indicated reduced nematode virulence in soil amended with fresh manure. Soil amended ...


A Financial Analysis Of A Teak Forest Managed For Sustained Production In West Java, Indonesia, Dedi Haryadi Jan 1994

A Financial Analysis Of A Teak Forest Managed For Sustained Production In West Java, Indonesia, Dedi Haryadi

Retrospective Theses and Dissertations

No abstract provided.


Papers On The Role Of Natural Resources In International Trade , Edward Osei Jan 1994

Papers On The Role Of Natural Resources In International Trade , Edward Osei

Retrospective Theses and Dissertations

In this work we present three papers that consider the economic implications of international trade in goods when exhaustible natural resources are used as inputs in the production process. In the first paper we investigate the possibility of violation of the static trade theorems when natural resource intensities in two goods are different. In this and the second paper we build on the generalized H-O framework of Kemp and Long (1984). The second paper analyzes the dynamic implications of incorporating natural resources into trade models. Issues relating to production and trade patterns and natural resource extraction rates are investigated under ...


Advanced Biotechnological Approaches And Gene Manipulation In Populus Species , Hoduck Kang Jan 1994

Advanced Biotechnological Approaches And Gene Manipulation In Populus Species , Hoduck Kang

Retrospective Theses and Dissertations

The biotechnology of plant tissue culture has been developed as an applied science for micropropagation, tree improvement, and basic physiology studies. Biotechnological approaches in forest science are advanced as a desirable tool to obtain superior genotypes and to screen for insect resistance. As a basic technique, in vitro cloning is a powerful tool using different explant types such as immature ovules or stem nodes for tree improvement. Typically, plants can be regenerated in vitro by apical or vascular cambial meristems. Genetic transformation is another option to improve the variable lines by genetic modification in host genetic materials with desirable traits ...


Evaluation Of Factors Influencing Grit Use By Birds , James Paul Gionfriddo Jan 1994

Evaluation Of Factors Influencing Grit Use By Birds , James Paul Gionfriddo

Retrospective Theses and Dissertations

Avian grit use was investigated by examining the gizzard contents of free-ranging birds and by conducting aviary experiments with captive birds. Free-ranging Iowa House Sparrows (Passer domesticus) were captured, and their gizzard grit was compared by sex, season, and diet. Males and females did not differ in mean grit amounts (overall x = 580 particles) or sizes, (overall x = 0.5 mm). Birds captured during March and August contained more grit than birds captured during September through February (x = 674 vs. 477). Gizzards containing >75% animal material (insects) had more grit than those containing, >75% plant food (x = 681 vs. 531 ...


Riparian Buffer Strips In The Bear Creek Watershed, Murielle Maud Bercovici Jan 1994

Riparian Buffer Strips In The Bear Creek Watershed, Murielle Maud Bercovici

Retrospective Theses and Dissertations

No abstract provided.


An Evaluation Of The Impacts Of Land Voiding Caused By Degrading Waterways: An Engineering Economic Approach, Landon Leath Morris Jan 1994

An Evaluation Of The Impacts Of Land Voiding Caused By Degrading Waterways: An Engineering Economic Approach, Landon Leath Morris

Retrospective Theses and Dissertations

No abstract provided.