Biology Commons^™

Cathodoluminescence Contrast Of Localized Defects Part I. Numerical Model For Simulation, K. L. Pey, D. S. H. Chan, J. C. H. Phang

Scanning Microscopy

A three-dimensional model has been developed for cathodoluminescence contrast of localized defects in semiconductors. The numerical model incorporates electron-solid interaction effects, charge transport phenomena and optical losses. Electron-solid interaction is modelled by a Monte Carlo method. Three-dimensional continuity equation and derivative boundary conditions are discretized by a central-difference quotients scheme. Localized defects are represented by regions of enhanced non-radiative recombination. The discretized linear difference equations of the boundary value problem are solved by the successive-over-relaxation method. A method for avoiding the divergence problem during the successive-over-relaxation calculation is illustrated. The solutions of the model are compared with the analytical results …

Cathodoluminescence Contrast Of Localized Defects Part Ii. Defect Investigation, K. L. Pey, J. C. H. Phang, D. S. H. Chan

Scanning Microscopy

Cathodoluminescence contrast from defects with different geometrical and electronic properties have been studied using the numerical model developed in Part I. The contrast of a localized subsurface defect exhibits a maxima at a specific beam energy E_max which corresponds to the depth of the defect. The contrast of a dis-location which intersects the top surface perpendicularly is a decreasing function of beam energy. The differences in the image profiles of the two different kinds of defects allow the two types of imperfections to be distinguished. In addition, the resolution of a subsurface defect at beam energies lower than E …

Effect Of Ototoxic Drugs On The Amphibian Auditory System: Injection Of Gentamicin Sulfate Into Anuran Otic Capsules And Recovery Of Thresholds, Michael Patrick Brown

Dissertations and Theses

Hair cell trauma from aminoglycosides, which may lead to permanent loss of hair cells in mammals, was studied physiologically in frogs by measuring an auditory evoked potential (AEP) in Rana pipiens. The AEP was evaluated in order to measure threshold shift (TS) and recovery from TS after the administration of the aminoglycoside antibiotic, gentamicin. To obtain an AEP, chronic electrodes were implanted into the cranium near the cochlear nucleus. The frogs were then exposed to frequency-specific narrow band "clicks" which included a single period 1 kHz sinewave, and a computer synthesized high frequency and low frequency click. Amphibians have two …

Apoptosis Induced By Microtubule Disrupting Drugs In Normal Murine Thymocytes In Vitro, Vladimir Bumbaširević, Andjelija Škaro-Milić, Aleksandar Mirčić, Bogdan Djuričić

Scanning Microscopy

Disruption of cytoplasmic and spindle microtubules by colchicine or nocodazole increases mitotic index, but it also enhances apoptosis in isolated mouse thymocytes; the apoptotic index exceeds 20% after 4 hours of incubation with either drug (5% in controls). Apoptosis was confirmed by DNA fragmentation, and was blocked by calcium chelators and inhibitors of protein synthesis. The apoptotic effect of microtubule disrupting drugs (MOD) was directed to interphase thymocytes and was independent on MOD action on mitotic cells. However, cell death of mitotically arrested cells showed ultrastructural changes similar in many aspects to apoptosis.

The Criminological Significance Of The Comparative Analysis Of Serum Albumins Using Electrophoresis And Immuno Gel Diffusion, Rhonda E. Ross-Ries

Whittier Scholars Program

Scientists and forensic experts are making use of macromolecules and their separation. Proteins are unique macromolecules produced by individuals and have provided key evolutionary genetic relationships. Two of the most common techniques used to separate proteins for analyzation electrophoresis and the Ouchterlony technique. The purpose of this comparative analysis project was to broaden the researcher’s laboratory skills to compare the two techniques in terms of efficiency,, cost efficiency, accuracy of results, and interpretation of results. Albumins were chosen for analysis because these proteins are known to be important to biology and are in great concentration in blood plasma.

Optical Microscopy And Atomic Force Microscopy Imaging Of 2,4,6-Trinitrotoluene Droplets And Clusters On Mica, D. O. Henderson, M. A. George, A. Burger, R. Mu, Zhiyu Hu, G. C. Huston

Scanning Microscopy

Optical and atomic force microscopy (AFM) were used to image 2,4,6-trinitrotoluene (TNT) on a cleaved mica (001) surface. The vapor deposition of TNT resulted in ellipsoidal drop formation on the mica surface. The growth rate of the drop diameter was found to be linear with vapor dosing time while the drop density followed a 1/r² dependence, where r is the length of the major axis of the ellipsoid, for increasing dosing times. TNT platelets surrounded by a region depleted of drops were observed after 8 hours of dosing. The depleted region is attributed to a 10% shrinkage for liquid-solid …

Post-Glacial Vegetational History Of The Great Bog, Belgrade, Maine, John Dawson

Senior Scholar Papers

A 6-m vibracore taken from the Great Bog in Belgrade, Maine, was sampled for pollen analysis at 10-cm intervals. Samples were processed in the laboratory using standard techniques developed by Faegri and Iversen. The sediment in the sample was reduced to a residue of pollen which was mounted on microscope slides. A minimum of 300 pollen grains was identified and counted at each level using a compound microscope at 400x magnification. Five radiocarbon dates were taken from the core at stratigraphic boundaries. Lastly, pollen concentration and pollen accumulation rates were calculated. The uppermost 3.8 m of the core is fine …

Use Of Microprojectile Bombardment In Transient Expression Assays To Analyze Protochlorophyllide Reductase Gene Expression In Greening Maize Seedling Leaf Cells, Jennifer J. Marden

Senior Scholar Papers

In young cells of leaf meristems the progenitors of chloroplasts are small organelles known as proplastids, which divide and differentiate into chloroplasts. However, in the absence of light, proplastids undergo a different sequence of development and become etioplasts. When light is supplied to etiolated plants during the "greening" process, etioplasts differentiate into chloroplasts containing chlorophyll. An important light dependent step in chlorophyll biosynthesis is the photoreduction of protochlorophyllide to chlorophyllide by the NADPH:protochlorophyllide reductase (PCR) enzyme. This enzyme is present at high activity only in etiolated tissue and during early stages of light-induced chlorophyll synthesis. The enzyme and its corresponding …

3 Genes Of The Map Kinase Cascade, Mek-2, Mpk-1/Sur-1 And Let-60 Ras, Are Required For Meiotic Cell-Cycle Progression In Caenorhabditis-Elegans, Diane L. Church, Kun Liang Guan, Eric J. Lambie

Dartmouth Scholarship

In the germline of Caenorhabditis elegans hermaphrodites, meiotic cell cycle progression occurs in spatially restricted regions. Immediately after leaving the distal mitotic region, germ cells enter meiosis and thereafter remain in the pachytene stage of first meiotic prophase for an extended period. At the dorsoventral gonadal flexure, germ cells exit pachytene and subsequently become arrested in diakinesis. We have found that exit from pachytene is dependent on the function of three members of the MAP kinase signaling cascade. One of these genes, mek-2, is a newly identified C. elegans MEK (MAP kinase kinase). The other two genes, mpk-1/sur-1 (MAP kinase) …

The Effect Of Arf-Excimer Laser Irradiation Of The Human Enamel Surface On The Bond Strength Of Orthodontic Appliances, U. Stratmann, K. Schaarschmidt, M. Schürenberg, U. Ehmer

Scanning Microscopy

This study investigated enamel laser conditioning as an alternative to acid etching in bracket therapy. In preliminary experiments optimal laser parameters for achieving a bond strength of 6-10 N/mm² were defined. Enamel surface morphology was assessed and the ablation depth was measured on serial enamel sections. Thirty human molars were exposed to 193 nm ArF-excimer laser radiation (energy density: 260 mJ/cm²) by single pulse application of 23 nanoseconds. Thirty molars were etched with phosphoric acid (37%) for 60 seconds. The brackets from the treated molars and 30 untreated molars were debonded vertically for tensile bond strength measurement. …

Synthesis Of Nitrosyl Metallpoprphyrins, Thomas M. Braxton Jr.

McCabe Thesis Collection

Nitric oxide, NO, is a molecule with great versatility and importance. Made up of only a single atom of nitrogen and a single atom of oxygen, nitric oxide is perhaps one of the smallest paramagnetic molecules found in nature. The functions of NO in the body are not all known, but this molecule definitely plays a variety of roles. It is involved in the regulation of blood pressure, and it sometimes acts as a messenger for cells as well as a killer of them. It also is important in the defense of the body against foreign invaders. The significance of …

The Nutritional Knowledge, Food Choices, And Exercise Habits Of Students At Langston University, Preston Solomon

McCabe Thesis Collection

The nutritional knowledge, food choice, and exercise habits of an individual determine his or her overall health and life expectancy. Information on these topics enables nutrition educators to develop strategies to improve knowledge and to tailor educational efforts which affect a large number of persons. Poor health in America today is an ever present reality. Heart disease, cancer, diabetes mellitus, cerebrovascular diseases, renal diseases, and pulmonary diseases are causes of death related in part to lack of nutritional knowledge and poor eating and exercise habits. A few of these diseases are chronic in nature and are the most deadly.

The …

Preliminary Keys To Carex (Cyperaceae) In New York State, Gordon Tucker

Faculty Research & Creative Activity

No abstract provided.

Preliminary Keys To Carex (Cyperaceae) In New York State, Gordon C. Tucker

Faculty Research & Creative Activity

No abstract provided.

Preliminary Keys To Carex (Cyperaceae) In New York State, Gordon C. Tucker

Faculty Research & Creative Activity

No abstract provided.

Circadian Rhythm Of Brain Gaba Levels In The Cockroach, Leucophaea Maderae, Juli Martin Mccay, Jeanette Marie Gibson

Mahurin Honors College Capstone Experience/Thesis Projects

Brain levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) were determined at three-hour intervals in roaches acclimated to a 12-hour lightl12-hour dark cycle (light onset 0600 h) at 25 ± 2° C using high performance liquid chromatography coupled with fluorometnc detection GABA levels were found to be highest at noon and lowest at 1800 h. A difference between the high and low levels at these two times remained during the second day under constant dark conditions, indicating that GABA levels do indeed vary on a circadian basis. Brain GABA levels were highest at a time of day that corresponded with …

The Bag And Size Limit Review: New Regulations And Summary Of Submissions, F. B. Prokop, J M. Collins

Fisheries Management Papers

Since the new bag and size limits were introduced in December 1991, there have been many suggestions for refinement and improvement of these regulations. This paper includes the summary of submissions to Fisheries Management Paper No 52 - Review of Bag and Size Limit Proposals for Western Australian Recreational Fishers and details new regulations which will come into force on 1 July 1995.

The Best Available Information - Its Implications For Recreational Fisheries Management, F. B. Prokop

Fisheries Management Papers

Workshop at Second National Fisheries Managers Conference, Bribie Island, Queensland, October 18, 1994. Recreational fisheries management is one of the growth areas in Australian fisheries. The Australian Society for Fish Biology Workshop topic for its 1994 Conference was Recreational Fishing - What's the Catch. It was acknowledged at the ASFB conference that there were generally poor levels of information and for the lower value commercial and recreational fisheries there may be no way to gather definitive research data for the foreseeable future. However, in even the high profile fisheries, public perceptions, attitudes, and political will do not allow for the …

Characterization Of Diverse 2,4-Dichlorophenoxyacetic Acid-Degradative Plasmids Isolated From Soil By Complementation, Eva M. Top, William E. Holben, Larry J. Forney

Biological Sciences Faculty Publications

The diversity of 2,4-dichlorophenoxyacetic acid (2,4-D)-degradative plasmids in the microbial community of an agricultural soil was examined by complementation. This technique involved mixing a suitable Alcaligenes eutrophus (Rif^r) recipient strain with the indigenous microbial populations extracted from soil. After incubation of this mixture, Rif^r recipient strains which grow with 2,4-D as the only C source were selected. Two A. eutrophus strains were used as recipients: JMP228 (2,4-D^-), which was previously derived from A. eutrophus JMP134 by curing of the 2,4-D-degradative plasmid pJP4, and JMP228 carrying pBH501aE (a plasmid derived from pJP4 by deletion of a …

Maintaining Bird Diversity In Western Larch/Douglas-Fir Forests, Bret W. Tobalske, Raymond C. Shearer, Richard L. Hutto

Biological Sciences Faculty Publications

Bird occurrences were evaluated under four stand conditions in western larch/Douglas-fir forests: clearcut, partial cut, unlogged (fragmented), and contiguous forest. Frequencies were noted for foraging guilds, tree gleaners, flycatchers, nesting guilds, tree drillers, and primary cavity nesters. Managers should consider a diversity of habitat conditions if maintaining habitat for bird species is an objective.

In Vitro Evaluation Of Anti-Eimeria Tenella, Gamont-Specific, Monoclonal Antibodies And Partial Characterization Of Their Target Antigens, Eric Wilson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study represents an effort to interrupt the life cycle of Eimeria tenella, the parasite that causes cecal coccidiosis in chickens, with a panel of 12 gamont-specific monoclonal antibodies (Mabs). To facilitate Mab screening, it was first necessary to develop a cell culture-adapted strain of E. tenella (field strain 80) from primary chicken kidney cells (PCKC) to white Leghorn chickens and back to PCKC. This alternation was repeated through 12 such passages. As a result, we have developed a cell culture-adapted strain of E. tenella that produces over 280% more oocysts in vitro than the original parent strain, and …

Functional Study Of The Structural Vp6 Protein Of Bluetongue Virus, Emiko Hayama

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study was undertaken to investigate the structure-function relationship of VP6 protein of bluetongue virus (BTV) using molecular cloning techniques. VP6 is present in small quantities in BTV and its enzymatic activity and role in the viral replication cycle have not been studied. Since the availability of large amounts of purified VP6 is essential for the analysis of VP6, a BTV-11 S3 gene was cloned into a prokaryotic protein expression system. VP6 protein was expressed in large amounts and purified to near homogeneity. A series of C-terminal and internal deletion mutants of S3 gene was constructed and the truncated VP6 …

Reproduction Of The Rare, Riparian Orchid Spiranthes Diluvialis: Pollination Ecology, Variations In Reproductive Success, And Implications For Conservation, Sedonia D. Sipes

Biology

I examined the reproductive biology and pollination of Ute lady's tresses, Spiranthes diluvialis Sheviak, a rare orchid from Colorado and Utah. S. diluvialis exhibits a mixed-mating system. Outcrossing is promoted by protandrous flowers and by acropetal movement of long-tongued bees (predominantly bumblebees) on inflorescences. However, male and female phases overlap, and flowers are fully self-compatible. No autogamous or agamospermous seed set was observed, indicating a pollinator is required for reproduction. Fruit set and pollinia removal varied greatly within and between flowering seasons. I found evidence for both resource and pollinator limitation of fruit set, and suggest that the limiting factor …

The Mayfly Newsletter, Peter M. Grant

The Mayfly Newsletter

The Mayfly Newsletter is the official newsletter of the Permanent Committee of the International Conferences on Ephemeroptera.

A Taxonomic Revision Of Neotropical Discocarpus (Euphorbiaceae), Sheila Mae Hayden

Master's Theses

This thesis is a taxonomic revision of Discocarpus, a genus of three species of trees from seasonally inundated forests of northern South America. Discocarpus is classified in the family Euphorbiaceae. The Euphorbiaceae or spurge family is a large and diverse taxon of angiosperms consisting of approximately 7000 species placed in 300 genera, comprising 49 tribes and 5 subfamilies (Webster 1994b). The origin of the family is likely Western Gondwanaland, and the earliest fossils identified as Euphorbiaceae date to the Paleocene (Raven & Axelrod 1974). The family is predominately tropical, however, species of Euphorbiaceae are important throughout most of the world …

Position Effect Variegation In Drosophila Is Associated With An Altered Chromatin Structure, Lori L. Wallrath, Sarah C.R. Elgin

Biology Faculty Research

A euchromatic gene placed in the vicinity of heterochromatin by a chromosomal rearrangement generally exhibits position effect variegation (PEV), a clonally inherited pattern showing gene expression in some somatic cells but not in others. The mechanism responsible for this loss of gene expression is investigated here using fly lines carrying a P element containing the Drosophila melanogaster white and hsp26 genes. Following mobilization of the P element, a screen for variegation of white expression recovered inserts at pericentric, telomeric, and fourth chromosome regions. Previously identified suppressors of PEV suppressed white variegation of pericentric and fourth chromosome inserts but not telomeric …

Lipopolysaccharide Core Structures In Rhizobium Etli And Mutants Deficient In O-Antigen, Russell W. Carlson, Bradley Reuhs, Tong-Bin Chen, U. Ramadas Bhat, K. Dale Noel

Biological Sciences Faculty Research and Publications

Lipopolysaccharide (LPS) is a major component of the bacterial outer membrane, and for Rhizobium spp. has been shown to play a critical role in the establishment of an effective nitrogen-fixing symbiosis with a legume host. Many genes required for O-chain polysaccharide synthesis are in the lps α region of the CE3 genome; this region may also carry lps genes required for core oligosaccharide synthesis. The LPSs from several strains mutated in the α region were isolated, and their mild acid released oligosaccharides, purified by high performance anion-exchange chromatography, were characterized by electrospray- and fast atom bombardment-mass spectrometry, NMR, and …

Arachidonic Acid As A Possible Negative Feedback Inhibitor Of Nicotinic Acetylcholine Receptors On Neurons, Sukumar Vijayaraghavan, Bo Huang, Edward M. Blumenthal, Darwin K. Berg

Biological Sciences Faculty Research and Publications

Neuronal acetylcholine receptors, being highly permeable to calcium, are likely to regulate calcium-dependent events in neurons. Arachidonic acid is a membrane-permeant second messenger that can be released from membrane phospholipids by phospholipases in a calcium-dependent manner. We show here that activation of neuronal acetylcholine receptors triggers release of ³H-arachidonic acid in a calcium-dependent manner from neurons preloaded with the fatty acid. Moreover, low concentrations of arachidonic acid reversibly inhibit the receptors and act most efficiently on receptors likely to have the highest permeability to calcium, namely receptors containing α7 subunits. Low concentrations of arachidonic acid also reversibly inhibit α7- …

Quantitative Analysis Of Electrotonic Structure And Membrane Properties Of Nmda-Activated Lamprey Spinal Neurons, C. R. Murphey, L. E. Moore, James T. Buchanan

Biological Sciences Faculty Research and Publications

Parameter optimization methods were used to quantitatively analyze frequency-domain-voltage-clamp data of NMDA-activated lamprey spinal neurons simultaneously over a wide range of membrane potentials. A neuronal cable model was used to explicitly take into account receptors located on the dendritic trees. The driving point membrane admittance was measured from the cell soma in response to a Fourier synthesized point voltage clamp stimulus. The data were fitted to an equivalent cable model consisting of a single lumped soma compartment coupled resistively to a series of equal dendritic compartments. The model contains voltage-dependent NMDA sensitive (^INMDA), slow potassium (I_{K …}

Cell Death In The Embryonic Developing Limb, J. M. Hurle, M. A. Ros, V. Garcia-Martinez, D. Macias, Y. Ganan

Scanning Microscopy

In amniote vertebrates, the development of form and structure of the limb bud is accompanied by precise patterns of massive mesodermal cell death with morphological features of apoptosis. These areas of cell death appear to eliminate undifferentiated cells which are required only for a limited time period of limb development. Predictable skeletal and morphological anomalies of the limb occur when the pattern of cell death is modified in mutant species or under experimental conditions. Most evidence points to the occurrence of local triggering mechanisms to account for the establishment of the areas of cell death and the subsequent activation of …