Digital Commons Network^™

A Phylogenetic Analysis Of Vertebrate And Invertebrate Notch-Related Genes, Eleanor M. Maine, James L. Lissemore, William T. Starmer

Biology - All Scholarship

Members of the Notch gene family are thought to mediate inductive cell-cell interactions during develop ment of a wide variety of vertebrates and invertebrates. These genes encode transmembrane proteins that appear to act as receptors and contain three repeated sequence motifs. Two of these motifs (an epidermal growth factor like sequence and a cdc10/SW16/ankyrin sequence) have been found in a large number of unrelated proteins, while the third motif (a lin-12/Notch/glp-1 sequence) is unique to proteins of the Notch family. We present a phylogenetic analysis of 17 Notch-related genes from eight species that has implications as to the origins and …

Enhancers Of Gzp1, A Gene Required For Cell-Signaling In Caenorhabditis Elegans, Define A Set Of Genes Required For Germline Development, Li Qiao, James L. Lissemore, Pei Shu, Anne Smardon, Melanie B. Gelber, Eleanor M. Maine

Biology - All Scholarship

The distal tip cell (DTC) regulates the proliferation or differentiation choice in the Cmorhabditis ekgans germline by an inductive mechanism. Cell signaling requires a putative receptor in the germline, encoded by the glp-1 gene, and a putative signal from the DTC, encoded by the lag-2 gene. Both glp-1 and lag-2 belong to multigene gene families whose members are essential for cell signaling during development of various tissues in insects and vertebrates as well as C. elegans. Relatively little is known about how these pathways regulate cell fate choice. To identify additional genes involved in the glp-1 signaling pathway, we carried …

Analysis Of The Multiple Roles Of Gld-I In Germline Development: Interactions With The Sex Determination Cascade And The Glp-1 Signaling Pathway, Ross Francis, Eleanor M. Maine, Tim Schedl

Biology - All Scholarship

The Caenorhabditis elegansgene gld-1 is essential for oocyte development; in gld-1 (null) hermaphrodites, a tumor forms where oogenesis would normally occur. We use genetic epistasis analysis to demonstrate that tumor formation is dependent on the sexual fate of the germline. When the germlines sex determination pathway is set in the female mode (terminal fem/fog genes inactive), gld-1 (null) germ cells exit meiotic prophase and proliferate to form a tumor, but when the pathway is set in the male mode, they develop into sperm. We conclude that the gld-1 (null) phenotype is cell-type specific and that gld-1 ( + ) acts …

The Effects Of Swimming Vs Running On Weight Loss In Small Mammals, David Ekkens, James Callan

Capstone Research Projects

No abstract provided.

Cathodoluminescence Of Rare Earth Doped Zircons. Ii. Relationship Between The Distribution Of The Doping Elements And The Contrasts Of Images, G. Rémond, P. Blanc, F. Cesbron, D. Ohnenstetter, O. Rouer

Scanning Microscopy

Cathodoluminescence (CL) color photographs using an optical CL microscope with a cold cathode electron gun are compared with non-spectrally resolved (polychromatic) and selected wavelength CL images obtained by means of a scanning electron microscope equipped with a CL spectrometer. It is the aim of this paper to show how the interpretation of the contrasts of CL images depends on the knowledge of the CL photon energy distributions participating to the observed contrasts as well as the matrix effects modifying the number of emitted photons compared to that of generated photons. It is shown that the impurities different from the rare …

Ultrafast Carrier Capture In Quantum Well Structures, P. W. M. Blom, J. E. M. Haverkort, J. Claes, P. J. Van Hall, J. H. Wolter

Scanning Microscopy

We present an experimental and theoretical study of the carrier capture time into a semiconductor quantum well. The carrier capture time was obtained by measuring both the rise of the quantum well (QW) population using time-resolved luminescence measurements and the decay of the barrier population using pump-probe correlation experiments. In the first technique, we compare the QW rise-times after direct (below the barrier band gap) and indirect (above the barrier band gap) excitation in order to eliminate the effects of relaxation and exciton formation in the quantum well.

We report the first experimental observation of oscillations in the carrier capture …

Optical Studies Of Ingaas/Gaas Multiple Quantum Wells (Mqw's) And Gaas/Si Using Novel Scanning Electron Microscopy Based Techniques, D. H. Rich, H. T. Lin, Y. Tang, K. Rammohan, A. Larsson

Scanning Microscopy

The influence of defects on electron-hole plasma transport in nipi-doped in _0.2Ga_0.8As/GaAs multiple quantum wells (MQWs) has been studied using a novel technique called electron beam induced absorption modulation (EBIA) imaging. Modulation doped MQW structures exhibit large optical nonlinearities and are important for the development of all-optical spatial light modulators used in optical computing and communication. The electron-hole plasma is generated by a high-energy electron beam in a scanning electron microscope and is used as a probe to study the MQW absorption modulation induced locally by the electron beam. The influence of structural defects on the …

Time-Resolved Luminescence From Two-Dimensional Electrons In High Magnetic Fields: A Tool For Studying The Fractional Quantum Hall Effect, Rolf J. Haug, Igor V. Kukushkin

Scanning Microscopy

Time-resolved magnetoluminescence investigations of specially doped AlGaAs/GaAs heterostructures allow the study of the electronic properties of two-dimensional electrons. The interactions of the two-dimensional electrons lead in high magnetic fields to the fractional quantum Hall effect. By analyzing the mean energy of the recombination line observed in the luminescence spectrum, the electronic properties of the fractional quantized states can be deduced. For negligible interaction between the charged acceptors and the interacting electron system, the derivative of the mean energy versus filling factor allows to obtain the jump of the chemical potential in crossing a fractional filling factor. From these jumps, the …

Genetic Structure Of Mosquitofish Populations In The Altamaha And Ogeechee Drainages Of Georgia: Reporting An Undescribed Form In The Ocmulgee River, Jose D. Hernandez-Martich, James M. Novak, Michael H. Smith, Paul E. Johns

Faculty Research & Creative Activity

An electrophoretic survey of genetic variation in mosquitofish populations of the Altamaha and Ogeechee drainages in Georgia revealed significant divergence (fs,=O.270) among populations within the Altamaha. Cluster analysis showed two lineages: one formed by populations from the Ogeechee drainage and the eastern and central Altamaha branches and another consisting of populations from the Ocmulgee River, the westernmost branch of the Altamaha drainage. These lineages may represent two independent forms. Average modified Rogers’ genetic distance was 0.25% between the two groups. The O_cmulgee lineage had significantly higher multilocus heterozygosity (H=0.206) than the other one (I-/=0.120). The high heterozygosity in the Ocmulgee …

Luminescence From Semiconductor Quantum Wires, Quantum Dots, And Monolayer Quantum Wells: Bottleneck And Localization Issues, C. M. Sotomayor Torres, P. D. Wang, N. N. Ledentsov, Y. -S. Tang, H. Qiang, F. H. Pollak, H. F. Ghaemi, B. B. Goldberg

Scanning Microscopy

Semiconductors nanostructures are fabricated using a range of techniques which inevitably have an impact in the resulting optical properties. Multilayers are grown by epitaxial techniques with a varying degree of uniformity in thickness, composition, etc., all leading to localisation effects in two-dimension. These multilayers are patterned to fabricate wires and dots using, in this case, electron beam lithography and dry etching. The fabrication steps contribute to modifications of the optical properties, beyond the expected purely confinement-related effects.

An overview of linear and modulation spectroscopy is presented to demonstrate the impact of fabrication steps as well as of lateral confinement upon …

Surface Recombination Velocity And Bulk Carrier Lifetime Measurement Of Silicon Crystals By Using Photoluminescence Time Decay, Karsten Thölmann, Masakazu Yamaguchi, Akihiro Yahata

Scanning Microscopy

The time decay for photoluminescence (PL) emitted from silicon crystals has been used to obtain both bulk carrier lifetime (Tb) and surface recombination velocity (S). Experimental results were interpreted with the assumptions that the sample was under a low-excitation condition and that the ratio of radiative to non-radiative recombination rates was constant throughout the carrier decay process. Analysis was applied to several wafers covered with different kinds of silicon dioxide (SiO₂). The results indicate that PL time decay measurement is effective to obtain the values of Tb and S.

Scanning Tunneling Microscope-Induced Luminescence Spectroscopy On Semiconductor Heterostructures, M. Pfister, M. B. Johnson, U. Marti, S. F. Alvarado, H. W. M. Salemink, D. Martin, F. Morier-Genoud, F. K. Reinhart

Scanning Microscopy

Scanning tunneling microscope (STM)-induced luminescence is explored as a technique for the characterization of semiconductor quantum wells and quantum wire heterostructures. By injecting minority carriers into the cleaved cross section of these structures, luminescence excitation on a nanometer scale is demonstrated. Using spectrally resolved STM-induced luminescence for the tip placed at various positions across the cleaved heterostructure, it is possible to obtain local spectroscopic information on closely spaced quantum structures.

Interpretation Of Cathodoluminescence Spectra Obtained From Dolomite And Calcite Gangue Minerals, And Dolostone Breccias In The Central Tennessee Zinc District (U.S.A.), Otto C. Kopp, E. Loren Fuller Jr., Michael R. Owen

Scanning Microscopy

Spectral patterns were obtained for zoned dolomite and unzoned calcite gangue, and dolostone breccia fragments from the Right Fork area in the central Tennessee zinc district (U.S.A.). The samples had been analyzed previously for Fe, Mn, and other trace elements using a synchrotron XRF probe. Spectra were obtained for zoned dolomite, breccia fragments, and unzoned calcite using an ELM2-B cold-cathode Luminoscope attached to an Oriel Multispec Compact Spectrograph. Spectra obtained for the prominent dolomite zones, which luminesce medium-bright to bright red to the eye, revealed a broad peak in the vicinity of 460 nm and a more intense peak in …

Ua66/6/3/1 Biennial Report, Kentucky Gamma, Alpha Epsilon Delta

Student Organizations

Biennial report created by and about the Kentucky Gamma Chapter of Alpha Epsilon Delta premedical honor society sponsored by WKU Biology.

Foraging Ecology Of The Mangrove Salt Marsh Snake, Nerodia Clarkii Compressicauda: Effects Of Vegetational Density [Abstract], Stephen J. Mullin, Henry R. Mushinsky

Faculty Publications

No abstract provided.

Association Of Mouse Fibrinogen-Like Protein With Murine Hepatitis Virus-Induced Prothrombinase Activity, Rebecca D. Parr, Laisum Fung, Jeffrey Reneker, Nancy Myers-Mason, Julian L. Leibowitz, Gary Levy

Faculty Publications

Previously, we demonstrated induction of a unique macrophage prothrombinase during infection of BALB/cJ mice by mouse hepatitis virus strain 3 (MHV-3). By immunologic screening, a clone representing this prothrombinase was isolated from a cDNA library and sequenced. The sequence identified this clone as representing part of a gene, musfiblp, that encodes a fibrinogen-like protein. Six additional clones were isolated, and one clone, p11-3-1, encompassed the entire coding region of musfiblp. Murine macrophages did not constitutively express musfiblp but, when infected with MHV-3, synthesized musfiblp-specific mRNA. musfiblp mRNA induction was earlier and significantly greater in BALB/cJ than A/J …

Molecular Mimicry Between Fc Receptor And S Peplomer Protein Of Mouse Hepatitis Virus, Bovine Corona Virus, And Transmissible Gastroenteritis Virus [Abstract], Emilia L. Oleszak, Jacek Kuzmak, Brenda Hogue, Rebecca D. Parr, Ellen W. Collisson, L. Scott Rodkey, Julian L. Leibowitz

Faculty Publications

No abstract provided.

Statistical Analyses Of Environmental Predictors For Phytoplankton Photosynthetic Parameters And Productivity In An Antarctic Time Series Database, Mark A. Moline, Barbara B. Prezelin, Oscar Schofield

Biological Sciences

No abstract provided.

Palmer Lter: Photoacclimation In A Coastal Phytoplankton Bloom, Oscar Schofield, Mark A. Moline, Barbara B. Prezelin

Biological Sciences

No abstract provided.

Induction Of Larval Settlement By Kcl In Three Species Of Bugula (Bryozoa), Dean E. Wendt, Robert M. Woollacott

Biological Sciences

Elevation of the K⁺ concentration in seawater (added as KCl) induces larval settlement and metamorphosis in Bugula simplex, B. stolonifera, and B. turrita. All three of these bryozoan species have similar bell-shaped dose-response curves: 5 mM excess K⁺ is sufficient to increase settlement and metamorphosis significantly over seawater controls in all the species and optimal responses to excess K concentrations occur ations at 10-25 mM, 5-10 mM, and 10-15 mM for B. simplex, B. stolonifera, and B. turrita, respectively. Percent settlement in all three species is decreased at levels greater than 25 mniM excess …

Three-Dimensional Thermoluminescence Spectra And Their Application In The Study Of Some Sedimentary Quartz, J. R. Prescott, R. B. Scholefield, A. D. Franklin

Scanning Microscopy

The intensity of thermoluminescence emission is a function of both temperature and photon energy (or wavelength) and therefore lends itself to a three-dimensional (3-D) display, either in the form of an isometric plot or a contour diagram. The technique of 3-D thermoluminescence spectrometry is briefly reviewed and the advantages and applications are illustrated by reference to the spectral properties of samples of Australian sedimentary quartz drawn from the context of thermoluminescence dating. In this context, the temperature of emission, the photon energy and the ease with which the emission is bleachable by sunlight are of significance. It is suggested that, …

Geographic And Nongeographic Variation In The Genus Microtus (Mammalia: Rodentia) In West Virginia, Tina M. Savage

Theses, Dissertations and Capstones

Geographic and nongeographic variation was assessed on 12 cranial and 4 external characters in approximately 400 specimens of Microtus (M. ochrogaster, M. chrotorrhinus, M. pinetorum, M. pennsylvanicus) in West Virginia. Univariate and multivariate statistical analyses were used to examine age-related variation, sexual dimorphism, elevation and geographic variation and litter size for each species of Microtus in the state. Cranial characters were more beneficial than external in detecting variation. Examination of data for each species of Microtus studied demonstrated that values and trends in variation is a specific rather than a generic trait. Age-related variation was present in some, …

The Effects Of An Early Season Clipping On Several Grassland Species, Bradley J. Matuska

Honors Theses, 1963-2015

In one year, the Proposed 100-Acres Quarry Park, Stearns County, Minnesota, USA, will be undergoing development. One aspect of the development is the management (i.e. burning, seeding, clipping) of an old grassland within the park. I studied clipping as a management scheme and expected the species richness (number of species) to increase after clipping and the prostrate species to respond better than the erect species. I used the Daubenmire Canopy-Coverage Method to measure my results. The species richness showed no significant change in response to clipping mainly due to the timing of the clipping. However, individual species responded differently to …

Small Mammals Of Quarry Park Stearns County, Mn, David Winecoff

Honors Theses, 1963-2015

This wilderness quarry area is in the process of being converted for public use by Stearns Co., and is an ideal area for ecological surveys. I assessed the small mammal distributions in the variety of habitat types within the park, from June to August 1994. The habitats included: grasslands, Oak, Aspen, and Red Pine forests, wetlands, rock tailing piles, natural rock outcroppings, and water-filled quarries. I conducted this survey using Sherman Live traps, scat boards, and pit traps. The grassland consisted exclusively of Microtus pennsylvanicus, except for a single Sorex cinereus. Peromyscus leucopis dominated in the forests within …

Bones Of Puffinus Lherminieri Lesson (Aves: Procellaridae) And Two Other Vertebrates From Cueva Del Agua, Mona Isalnd, Puerto Rico (West Indies), Angel M. Nieves-Rivera, John M. Mylroie, Donald A. Mcfarlane

WM Keck Science Faculty Papers

From a dive in Cueva del Agua, Mona Island, Puerto Rico, twelve un-mineralized bones of Puffinus Lherminieri Lesson, one of Cyclura stejnegeri Stejneger, and one of Moormops blainvilii Leach were collected. The subfossil evidence confirms that P. Lherminieri was a common species on Mona Island. Cyclura stejnegeri and M. blainvilii probably became trapped and died in the pool chamber.

The Effects Of Nutrient Loading On Plant And Algae Population: A Comparison Study Of East Gemini Lake And Lower Stumpf Lake, Nick Leonard

Honors Theses, 1963-2015

Eutrophication of lakes has become an increasing problem for many bodies of water. By analyzing the nutrients available and the phytoplankton and macrophyte populations, evaluation and differentiation of East Gemini Lake and Stumpf Lake were made concerning their trophic state. This determination allowed for the further understanding of the effect the trophic state has on the flora of an aquatic system. It was determined that East Gemini Lake was eutrophic based on its available nutrients and phytoplankton populations. In contrast, Stumpf Lake was determined to be mesotrophic having lower available nutrients and less phytoplankton population density with fewer major phytoplnakton …

Effects Of Silvicultural Treatments In The Rocky Mountains, Sallie J. Hejl, Richard L. Hutto, Charles R. Preston, Deborah M. Finch

Biological Sciences Faculty Publications

We offer a description of current forest structure and basic information on bird distribution across forest habitats in the Rockies as background knowledge for understanding the effects of silviculture on birds in these habitats. We also offer a comparison between the effects of silviculture, and the effects of fire and fire suppression on forest birds in an attempt to give a holistic perspective on the health of forest birds' in the Rockies.

A Comparison Of Bird Detection Rates Derived From On-Road Versus Off-Road Point Counts In Northern Montana, Richard L. Hutto, Sallie J. Hejl, Jeffrey F. Kelly, Sandra M. Pletschet

Biological Sciences Faculty Publications

We conducted a series of 275 paired (on- and off-road) point counts within 4 distinct vegetation cover types in northwestern Montana. Roadside counts generated a bird list that was essentially the same as the list generated from off-road counts within the same vegetation cover type. Species that were restricted to either on- or off-road counts were rare, suggesting that restricted occurrences were a consequence of small sample sizes and not a product of habitat differences surrounding on-versus off-road points. Nevertheless, there were significant differences in the mean number of individuals detected between on- and off-road points for a number of …

Cathodoluminescent Properties Of Single Crystal Materials For Electron Microscopy, Rudolf Autrata, Petr Schauer

Scanning Microscopy

The results of measurements of cathodoluminescence efficiencies, decay characteristics and emission spectra of YAG:Ce, YAP:Ce, P47 (Y₂SiO₅:Ce) and CaF₂:Eu single crystals at excitation by electrons with an energy of 10 keV and a current density of the order of 10^-8 A cm^-2 are presented. Advantages and disadvantages of the individual single crystals intended for application in electron microscopes are dealt with. Attention is paid to the photomultiplier tube (PMT) matching, degradation and afterglow of the mentioned single crystals. For YAG:Ce, the effect of the activator concentration of crystals and the effect of …

Can Photo- And Cathodoluminescence Be Regarded As Complementary Techniques?, S. Myhajlenko, R. A. Puechner, J. L. Edwards, D. B. Davito

Scanning Microscopy

Photoluminescence (PL) usually provides macroscopic, high quality spectroscopic data. Cathodoluminescence (CL), on the other hand, offers the same information with microscopic imaging. However, replicating PL signatures in a CL system is not straightforward since matching experimental conditions, such as temperature and excitation density, is difficult. The matter is further exacerbated by inherent differences in the nature of excitation: electrons versus photons. Our work with high purity semiconductors suggests that CL is generally more sensitive to excitation "circumstance" than PL. For example, electrons can cause sample charging and contamination-related phenomena that dramatically affect CL. Changes in surface attributes (e.g., by chemical …