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Efficiency Of The Secondary Electron Detector In The Scanning Electron Microscope, Zbigniew Czyzewski, David C. Joy

Scanning Microscopy

The efficiency of the secondary electron detector in the scanning electron microscope (SEM) is one of the most important factors affecting the imaging process of the SEM. To compute the detector efficiency, the electrostatic field inside a specimen chamber must be known. A simple way of performing such calculations is to use a spreadsheet program which has a built-in capability of storing and performing some operations on three-dimensional matrices. Using a spreadsheet program makes it possible to solve the Laplace equation and calculate electron trajectories in geometrically complex electrostatic fields. This technique is applied to the estimation of detector efficiency …

Energy Loss Function And Source Function For Au 4f Photoelectrons Derived By Monte Carlo Analysis Of Reflection Electron Energy Loss Spectroscopy (Reels) And X-Ray Photoelectron Spectroscopy (Xps) Spectra, H. Yoshikawa, T. Tsukamoto, R. Shimizu

Scanning Microscopy

We have derived the energy loss function of Au for 1 keV electrons by Monte Carlo analysis of the reflection electron energy loss spectroscopy (REELS) spectra. This energy loss function was significantly different from the optical loss function widely used and has revealed that the surface excitation affects the energy loss spectrum of keV electrons.

X-ray photoelectron spectroscopy (XPS) background subtraction has been recently developed by using the energy loss function derived from the transmission electron energy loss spectroscopy (TEELS). We have demonstrated that the energy loss function derived from REELS has enabled a more accurate Au 4f XPS spectrum …

A Survey Of Electron Probe Microanalysis Using Soft Radiations: Difficulties And Presentation Of A New Computer Program For Wavelength Dispersive Spectrometry, M. Fialin, J. Hénoc, G. Remond

Scanning Microscopy

This paper aims to demonstrate that on-line peak integral technique with wavelength dispersive spectroscopy (WDS) provides accurate results with intensity measurement counting times as short as one or two minutes, owing to the high counting rates obtained with multilayer analyzers. A great advantage of a new computer program using this technique (available on SUN/UNIX work-stations operating Cameca SX-50 microprobes) consists in the original way that peak overlaps are treated. For each analytical point, overlapping counts emerging from an element B (B counts) are removed on-line from the measured raw counts in order to obtain the net counts corresponding to the …

Standardless Quantitative Analysis By X-Ray Spectrometry, János L. Lábár

Scanning Microscopy

Errors in standardless analysis arise from inaccuracies in atomic data, detection efficiency of the detector, the normalization and the sensitivity to the errors of the spectrum processing, and ZAF correction (which converts the ratio of the measured intensities into concentration). Other sources of error encountered in fully quantitative analysis (using standards) also remain in the standardless version. Calculation of the L_α standard intensities also requires incorporation of non-radiative transitions. Both the experimentally found dependence of the net L_α intensities on the atomic number and the corresponding peak-to-background ratios (P/B) indicate that an empirical increase in the …

Contrast Mechanism Of Scanning Tunneling Microscopy: The Two-Sided Point Of View, C. Julian Chen

Scanning Microscopy

It has been known for three decades that tunneling experiments should be explained by the electronic structures of both electrodes. Scanning tunneling microscopy (STM) is no exception. Since the development of STM in the early 1980s, experimental facts have repeatedly shown the necessity to explain the STM images and tunneling spectra from a two-sided point of view. In other words, the STM images and tunneling spectra should be explained by the interaction of the electron density distributions of the tip and the sample (in energy and space). In the early years of STM, due to a scarceness of experimental …

Aquatic Insects Of Upper Three Runs Creek, Savannah River Plant, South Carolina. Part Iv: Caddisflies (Trichoptera) Of The Lower Reaches, Michael A. Floyd, John C. Morse, J Vaun Mcarthur

Publications

Ninety-three species of caddisflies, representing 14 families, were identified from collections obtained from two localities on Upper Three Runs Creek, Savannah River Site, Aiken County, South Carolina. Collections of adult caddisflies were made biweekly over a 1-yr period with ultraviolet light traps. The similarity index, Jaccard's Coefficient of Communities, showed that the two sites were over 78% similar with 73 species in common. Three species, Oxyethira setosa Denning, Triaenodes smithi Ross, and Nyctiophylax serratus Lago & Harris, are new distributional records for South Carolina. Two species of Triaenodes are new to science. Other species, which were considered to be endemic …

The Effect Of Environmental Calcium Concentrations On Zebra Mussel (Dreissena Polymorpha) Shell Composition, Marty Roers

Honors Theses, 1963-2015

The calcium content of zebra mussel shells from eight different natural and experimental waters was analyzed. Large control Lake Superior shells have less calcium compared to large shells from the other Great Lakes. The shells' calcium content was dependent upon the environmental calcium level and the length of the growth period spent at each condition. An inverse relationship exists between the size and calcium content of zebra mussel shells. The calcium compounds (CaCO₃ or CaCl₂) in experimentally hardened water had no effect on shell composition.

Field Notes, Jonathan L. Dunnum

Division of Mammals - Field Notes and Catalogs

No abstract provided.

Intragenic Dominant Suppressors Of Glp-1, A Gene Essential For Cell-Signaling In Caenorhabditis Elegans, Support A Role For Cdcl O/Swz6/Ankyrin Motifs In Glp-1 Function, James L. Lissemore, Peter D. Currie, Christine M. Turk, Eleanor M. Maine

Biology - All Scholarship

The glp-1 gene product mediates cell-cell interactions required for cell fate specification during development in Caenorhabditis elegans. To identify genes that interact with glp-1, we screened for dominant suppressors of two temperature-sensitive glp-1 alleles and recovered 18 mutations that suppress both germline and embryonic glp-1 phenotypes. These dominant suppressors are tightly linked to glp-1 and do not bypass the requirement for a distal tip cell, which is thought to be the source of a signal that is received and transduced by the GLP-1 protein. Using single-strand conformation polymorphism (SSCP) analysis and DNA sequencing, we found that at least 17 suppressors …

Suppressors Of Glp-1, A Gene Required For Cell Communication During Development In Caenorhabditis Elegans, Define A Set Of Interacting Genes, Eleanor M. Maine, Judith Kimble

Biology - All Scholarship

The glp-1 gene is essential for two cell interactions that control cell fate in Caenorhabditis elegans: induction of anterior pharynx in the embryo and induction of mitotic proliferation in the germ line. To identify other genes involved in these cell interactions, we have isolated suppressors of two temperature sensitive alleles of glp-1. Each of 14 recessive suppressors rescues both embryonic and germline glp-1(ts) defects. These suppressors are extragenic and define a set of six genes designated sog, for suppressor of glp-1. Suppression of glp-1 is the only obvious phenotype associated with sog mutations. Mutations in different sog genes show allele-specific …

Temperature, Activity And Lizard Life Histories, Stephen C. Adolph, Warren P. Porter

All HMC Faculty Publications and Research

Lizard life-history characteristics vary widely among species and populations. Most authors seek adaptive or phylogenetic explanations for life-history patterns, which are usually presumed to reflect genetic differences. However, lizard life histories are often phenotypically plastic, varying in response to temperature, food availability, and other environmental factors. Despite the importance of temperature to lizard ecology and physiology, its effects on life histories have received relatively little attention. We present a theoretical model predicting the proximate consequences of the thermal environment for lizard life histories. Temperature, by affecting activity times, can cause variation in annual survival rate and fecundity, leading to a …

Phylogenetics Of Seed Plants: An Analysis Of Nucleotide Sequences From The Plastid Gene RbcL, James F. Smith

Biology Faculty Publications and Presentations

We present the results of two exploratory parsimony analyses of DNA sequences from 475 and 499 species of seed plants. respectively, representing all major taxonomic groups. The data are exclusively from the chloroplast gene rbcL, which codes for the large subunit of ribulose-l .5-bisphosphate carboxylase/ oxygenase (RuBisCO or RuBPCase). We used two different state-transformation assumptions resulting in two sets of cladograms: (i) equal-weighting for the 499-taxon analysis; and (ii) a procedure that differentially weights transversions over transitions within characters and codon positions among characters for the 475-taxon analysis. The degree of congruence between these results and other molecular. as …

A Review Of The Biology Of Giant Salvinia, J. Douglas Oliver

Faculty Publications and Presentations

Giant salvinia (Salviniaceae) is a potentially serious aquatic weed that is native to Brazil. It has been reported in more than 20 countries, but is not established in the U.S. at this time. Mitchell and Tur (1975) reported that three years after the formation of the Kariba Reservoir in Africa, giant salvinia blanketed 21.5% or 1003 km2 of the reservoir surface area. Creagh (199111992) wrote, "A single small plant may grow to form a thick mat covering more than 100 sq. km. in just three months - choking lakes and waterways, reducing populations of aquatic plants and animals and in …

Woody Vegetation Of A Disjunct Bur Oak (Quercus Macrocarpa) Forest In East-Central Nebraska, Debra Ann Beightol, Thomas B. Bragg

Biology Faculty Publications

Woody plant composition was assessed for three tree-size classes in two ravines of Oak Glen Wildlife Management Area, a disjunct oak forest in Seward County, Nebraska, using Importance Values (IV) obtained by the Point-Quarter method. Bur oak (Quercus macrocarpa Michx.) dominated the large-size class (>30 cm dbh) (IV = 258) but elms (Ulmus americana L. and U. rubra Muhl.) (IV = 130) dominated the forest in one ravine in the medium-size class (10-30cm dbh) and elm and hackberry (Celtis occidentalis L.) (IV = 114 and 27 respectively) dominated the small-size class (

Review Of American Wildflower Florilegium By Jean Andrews, David M. Sutherland

Biology Faculty Publications

This book is a collection of 50 watercolor paintings of American wildflowers ("florilegium" means, literally, "a gathering of flowers"). Accompanying each full-page painting is a summary of general information about the plant, including notes about its botanical classification, the etymology of its name, life history, distribution, description, flowering period, pollination, and propagation.

Floristic Diversity In Ten Tallgrass Prairie Remnants Of Eastern Nebraska, Judith F. Boettcher, Thomas B. Bragg, David M. Sutherland

Biology Faculty Publications

Ten eastern Nebraska tallgrass prairie remnants, varying in size from one to 18 ha, were studied or visited during the growing seasons from 1979 to 1993. A total of217 prairie plant species were recorded. Big bluestem (Andropogon gerardii), little bluestem (Andropogon scoparius), smooth brome (Bromus inermis subsp. inermis), New Jersey tea (Ceanothus herbaceus var. pubescens), false sunflower (Heliopsis helianthoides var. scabra), Kentucky bluegrass (Poa pratensis), and porcupine-grass (Stipa spartea) were prevalent in all the prairies although the specific floristic composition has been reported to vary depending on past management, topography, season of evaluation, and prairie size. Of the total species …

Factors Influencing Variation In Susceptibility Of Prairie Plants To An Early Summer Frost In East-Central Minnesota, Bette L. Purnell '93

Honors Projects

This study was conducted to determine the factors affecting susceptibility of prairie plants to an early summer frost at Cedar Creek Natural History Area, in east-central Minnesota. Data were collected in a previously established experimental field after temperatures fell to 1.3 °C on 20 June 1992, and to 0.3 °c on 21 June 1992. The degree of frost damage to prairie plants was recorded using a scale of frost damage based on visual criteria, and possible causes of variation in frost susceptibility were examined. The degree of frost damage was independent of plant type (grass or forb), life cycle (annual, …

Ultrastructure Of The Coeloms Of Auricularia Larval (Holothuroidea Echinodermata): Evidence For The Presence Of An Axocoel, E. J. Balser, E. E. Ruppert, William Jaeckle

Scholarship

A hallmark feature of echinoderm larvae is the development of the left anterior coelom. This coelom, called the axohydrocoel, consists of the morphologically distinct, but undivided, left axocel and hydrocel. The axocoelic portion forms a duct that opens to the exterior via a pore on the dorsal surface of the animal. Holothuroid larvae are thought to lack an axocoel, but develop an anterior coelom, duct, and pore that are regarded as parts of the hydrocoel. New ultrastructural data, however, show that holothuroid auricularia larvae possess an axocel and hydrocel united together into an axohydrocoel. During development the anterior coelom consists …

Live Northern Harrier Entrapped In Ice, Given Harper, Thomas Dunstan

Scholarship

No abstract provided.

Phylogenetic Analysis Of The Zingiberales Based On RbcL Sequences, James F. Smith, W. John Kress, Elizabeth A. Zimmer

Biology Faculty Publications and Presentations

Morphological data have been used previously to construct phylogenies of the eight families of the Zingiberales one of the most widely accepted monophyletic groups of flowering plants. To provide additional support for phylogenetic relationships within the order, and placement of the order among monocots, we present a parsimony analysis of DNA sequences from the chloroplast-encoded gene, rbcL, for 21 species of Zingiberales and proposed relatives. Five analyses with equal, and differential weights were performed. All analyses resulted in the same most parsimonious tree for taxa within the Zingiberales and the immediate outgroup. The closest sister group to the Zingiberales …

Phylogenetic Hypotheses For The Monocotyledons Constructed From RbcL Sequence Data, James F. Smith

Biology Faculty Publications and Presentations

DNA sequences for the plastid locus that encodes the large subunit if ribulose 1.5 bisphosphate carboxylase/oxygenase (rbcL) were determined for 18 species of monocotyledons in 15 families. These data were analyzed together with sequences for 60 other monocot species in a total of 52 families by the maximum likelihood method producing one, presumably optimal, topology. An additional 26 species were added (104 total monocot species) and analyzed by the parsimony method with an outgroup of 18 dicot species producing 109 trees of 3,932 steps. The rbcL data show at least moderate support for seven lineages corresponding to …

Phytoplankton Relationships To Water Quality In Lake Drummond And Two Drainage Ditches, Christine G. Phillips, Harold G. Marshall

Biological Sciences Faculty Publications

A twelve-month phytoplankton study was conducted in Lake Drummond and Washington and Jericho Ditches from December 1988 to November 1989. Four dominant phytoplankton groups were identified at these sites. These were the Bacillariophyceae, Cyanophyceae, Cryptophyceae and an autotrophic picoplankton component. Over the past 20 years there has been a decrease in the mean pH levels of Lake Drummond and the replacement of one its former major components, the Chlorophyceae, by the Cyanophyceae. Based on water quality analysis results and species diversity indices, Lake Drummond is classified as in an early eutrophic stage of development.

Impact Of Elementary Teachers’ Science Backgrounds On The Teaching Of Science In Iowa Elementary Classrooms, Nancy Lynn Heiter

Dissertations and Theses @ UNI

The purpose of this study was to investigate the high school and college science background of elementary teachers in Iowa and to relate this background to the amount of time these teachers spend teaching about science. The population from which this sample was drawn consisted of elementary school teachers in Iowa. A stratified random sample of schools based on school district size was used. Surveys were mailed to principals, who were asked to distribute the surveys to teachers. From the population surveyed, 475 teachers participated in the study. The chi square analysis was used to show relationships between data collected. …

Determinants Of Success In Experimental Introductions Of The Rodent (Mus Musculus) Onto Habitat Islands, Mark W. Krissinger

College of Graduate Studies: Theses & Dissertations (1964–2006)

I conducted an experimental test of the influence of supplemental food on persistence time of intentionally introduced (i.e. translocated) mice (Mus musculus) on four habitat islands. I determined the species composition of small mammals in the four insular patches of habitat (i.e. habitat islands) formed by Interstate Highway 16 and associated access roads at the US Hwy 301 interchange using standard live-trapping methods. Two of the habitat islands supported three resident rodent species, whereas the other two each supported one species.

After determining the initial species composition of the four habitat islands I released 14 uniquely marked individuals …

Acid-Base Regulation In Three Marine Teleosts: The Oyster Toadfish (Opsanus Tau), The Winter Flounder (Pseudopleuronectes Americanus), And The Long-Horned Sculpin (Myoxocephalus Octodecimspinosus), Dana Compton Mccullough

College of Graduate Studies: Theses & Dissertations (1964–2006)

In this study, three species of marine fish were exposed to a variety of dilute salinities in order to determine what effects exposure to diluted seawater may have on acid-base and ion balance. The oyster toadfish (Opsanus tau) and the winter flounder (Pseudopleuronectes americanus) are considered to be able to live in a broad range of salinities, euryhaline (Evans, 1979). The long-homed sculpin, Myoxocephalus octodecimspinosus, is considered to be a stenohaline fish, not able to withstand drastic changes in ambient salinity (Claibome and Evans, 1988).

Initially, toadfish exposed to 20 mM diluted seawater took up …

Specimen Catalog, Pablo M. Marquet

Division of Mammals - Field Notes and Catalogs

No abstract provided.

Why Do Primates Have Such Long Lifespans And So Few Babies, Eric Charnov, David Berrigan

Biology Faculty & Staff Publications

Life history allometries for primates versus other mammals are studied

The M/K Ratio Is The Same For Fish And Reptiles, Eric Charnov, David Berrigan, Richard Shine

Biology Faculty & Staff Publications

No abstract provided.

Specimen Catalog & Field Notes, Sara V. Brant

Division of Mammals - Field Notes and Catalogs

No abstract provided.

The Functional Analysis Of Nonsense Suppressors Derived From In Vitro Engineered Saccharomyces Cerevisiae TrnaTrp Genes, Audrey L. Atkin, M. A. Riazia, C. L. Greer, K. L. Roye, J. B. Bell

School of Biological Sciences: Faculty Publications

Nonsense suppressors derived from Saccharomyces cerevisiae tRNA^Trp genes have not been identified by classical genetic screens, although one can construct efficient amber (am) suppressors from them by making the appropriate anticodon mutation in vitro. Herein, a series of in vitro constructed putative suppressor genes was produced to test if pre-tRNA^Trp processing difficulties could help to explain the lack of classical tRNA^Trp-based suppressors. It is clear that inefficient processing of in-trons from precursor tRNA^Trp, or inaccurate overall processing, may explain why some of these constructs fail to promote nonsense suppression in vivo. However, deficient processing …