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2006

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Articles 121 - 150 of 536

Full-Text Articles in Biology

Phylogeographic Analyses Of Obligate And Facultative Cave Crayfish Species On The Cumberland Plateau Of The Southern Appalachians, Jennifer Elizabeth Buhay Jul 2006

Phylogeographic Analyses Of Obligate And Facultative Cave Crayfish Species On The Cumberland Plateau Of The Southern Appalachians, Jennifer Elizabeth Buhay

Theses and Dissertations

Cave systems and their unique biota are widely viewed as highly endangered, yet very little is known about basic life history, ecology, distributions, habitat requirements, and evolutionary relationships of subterranean species. The crux of the problem in cave studies is the assumption that traditionally defined morpho-species represent distinct evolutionary lineages. Convergence is exhibited in the morphologies of many animal groups, vertebrate and invertebrate, which leads to confusion in diagnosing species' boundaries, geographic distributions, gene flow routes, and imperilment. This dissertation research includes phylogeographic analyses of freshwater cave-dwelling crayfishes in the Southern Appalachians, a global hotspot of subterranean biodiversity. By examining …


Development Of An In Vitro Protocol To Study The Effect Of Estrogen On Osteoblast Activity, Sourik Ganguly Jul 2006

Development Of An In Vitro Protocol To Study The Effect Of Estrogen On Osteoblast Activity, Sourik Ganguly

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science & Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Sourik Ganguly on July 7, 2006.


Evaluating Sedimentary Geochemical Lake-Level Tracers In Walker Lake, Nevada, Over The Last 200 Years, Fasong Yuan, Braddock K. Linsley, Stephen S. Howe Jul 2006

Evaluating Sedimentary Geochemical Lake-Level Tracers In Walker Lake, Nevada, Over The Last 200 Years, Fasong Yuan, Braddock K. Linsley, Stephen S. Howe

Biological, Geological, and Environmental Faculty Publications

Walker Lake, a hydrologically closed, saline, alkaline lake located along the western margin of the Great Basin of western United States, has experienced a 77% reduction in volume and commitment drop in lake level as a result of anthropogenic perturbations and climatic fluctuations over the last century. The history of lake-level change in Walker Lake has been recorded instrumentally since 1860. A high-resolution multi-proxy sediment core record from Walker Lake has been generated through analysis of total inorganic carbon (TIC), total organic carbon (TOC), and oxygen and carbon isotope ratios (δ18O and δ13 C) of both downcore …


Identification Of Anopheles (Nyssorhynchus) Marajoara (Diptera: Culicidae) In Bolivia Using Polymerase Chain Reaction And A Restriction Endonuclease, Gary Fritz, C. Brelsfoard, R. Rodriguez Jul 2006

Identification Of Anopheles (Nyssorhynchus) Marajoara (Diptera: Culicidae) In Bolivia Using Polymerase Chain Reaction And A Restriction Endonuclease, Gary Fritz, C. Brelsfoard, R. Rodriguez

Faculty Research & Creative Activity

Anopheles (Nyssorhynchus) marajoara Galvão & Damasceno (Diptera: Culicidae) is a member of the Albitarsis cryptic species complex and is a primary vector of human Plasmodium in parts of Brazil. We report the first record of An. marajoara in the department of Cochabamba and confirm its presence in the department of Santa Cruz, Bolivia. We also describe a PCR protocol producing a single amplicon (≈340 bp) of a section of the internal transcribed spacer 2 specific for members of the Albitarsis species complex; the polymerase chain reaction protocol did not amplify the DNA of 17 other species in the subgenus Nyssorhynchus. …


Identification Of Anopheles (Nyssorhynchus) Marajoara (Diptera: Culicidae) In Bolivia Using Polymerase Chain Reaction And A Restriction Endonuclease, Gary Fritz, C. L. Brelsfoard, R. Rodriguez Jul 2006

Identification Of Anopheles (Nyssorhynchus) Marajoara (Diptera: Culicidae) In Bolivia Using Polymerase Chain Reaction And A Restriction Endonuclease, Gary Fritz, C. L. Brelsfoard, R. Rodriguez

Faculty Research & Creative Activity

Anopheles (Nyssorhynchus) marajoara Galvão & Damasceno (Diptera: Culicidae) is a member of the Albitarsis cryptic species complex and is a primary vector of human Plasmodium in parts of Brazil. We report the first record of An. marajoara in the department of Cochabamba and confirm its presence in the department of Santa Cruz, Bolivia. We also describe a PCR protocol producing a single amplicon (≈340 bp) of a section of the internal transcribed spacer 2 specific for members of the Albitarsis species complex; the polymerase chain reaction protocol did not amplify the DNA of 17 other species in the subgenus Nyssorhynchus. …


Soil Microbial Community Composition As Affected By Restoration Practices In California Grassland, Rebecca E. Drenovsky, Martin Pothoff, Kerri L. Steenwerth, Louise E. Jackson, Rainer G. Joergensen, Kate M. Scow Jul 2006

Soil Microbial Community Composition As Affected By Restoration Practices In California Grassland, Rebecca E. Drenovsky, Martin Pothoff, Kerri L. Steenwerth, Louise E. Jackson, Rainer G. Joergensen, Kate M. Scow

Biology

Agricultural practices have strong impacts on soil microbes including both the indices related to biomass and activity as well as those related to community composition. In a grassland restoration project in California, where native perennial bunchgrasses were introduced into non-native annual grassland after a period of intensive tillage, weeding, and herbicide use to reduce the annual seed bank, microbial community composition was investigated. Three treatments were compared: annual grassland, bare soil fallow, and restored perennial grassland. Soil profiles down to 80cm in depth were investigated in four separate layers (0–15, 15–30, 30–60, and 60–80cm) using both phospholipid ester-linked fatty acid …


Anti-Viral Capacity Of Quillaja Saponaria Molina Extract Against Vaccinia And Herpes Simplex Virus-1, Matthew Sean Spinks Jul 2006

Anti-Viral Capacity Of Quillaja Saponaria Molina Extract Against Vaccinia And Herpes Simplex Virus-1, Matthew Sean Spinks

Biology Theses - Archive

It is well known that Quillaja saponins have the ability to elicit a strong immune response when used as an adjuvant in an ISCOM matrix. However, to date, the antiviral capability of Quillaja saponins has not been documented. Using extracts from the Chilean Soap Bark Tree (Quillaja Saponaria Molina) we document the anti-viral capacities of Quillaja saponins against HSV-1 and Vaccinia. The saponin was ineffective against Vaccinia Virus, however neutralized HSV-1 in a time and temperature dependent manner. In addition, Quillaja Saponins were determined capable of preventing cell-to-cell spread when introduced in solution to cell monolayers.


Transport Of Galectin-3 Between The Nucleus And Cytoplasm. I. Conditions And Signals For Nuclear Import, Peter J. Davidson, Su Yin Li, Andrew G. Lohse, Rianna Vandergaast Jul 2006

Transport Of Galectin-3 Between The Nucleus And Cytoplasm. I. Conditions And Signals For Nuclear Import, Peter J. Davidson, Su Yin Li, Andrew G. Lohse, Rianna Vandergaast

University Faculty Publications and Creative Works

Galectin-3, a factor involved in the splicing of pre-mRNA, shuttles between the nucleus and the cytoplasm. We have engineered a vector that expresses the fusion protein containing the following: (a) green fluorescent protein as a reporter of localization, (b) bacterial maltose-binding protein to increase the size of the reporter polypeptide, and (c) galectin-3, whose sequence we wished to dissect in search of amino acid residues vital for nuclear localization. In mouse 3T3 fibroblasts transfected with this expression construct, the full-length galectin-3 (residues 1-263) fusion protein was localized predominantly in the nucleus. Mutants of this construct, containing truncations of the galectin-3 …


Ecological Fitting As A Determinant Of The Community Structure Of Platyhelminth Parasites Of Anurans, Daniel R. Brooks, Virginia León-Règagnon, Deborah Mclennan, Derek Zelmer Jul 2006

Ecological Fitting As A Determinant Of The Community Structure Of Platyhelminth Parasites Of Anurans, Daniel R. Brooks, Virginia León-Règagnon, Deborah Mclennan, Derek Zelmer

Faculty Publications

Host–parasite associations are assumed to be ecologically specialized, tightly coevolved systems driven by mutual modification in which host switching is a rare phenomenon. Ecological fitting, however, increases the probability of host switching, creating incongruences between host and parasite phylogenies, when (1) specialization on a particular host resource is a shared characteristic of distantly related parasites, and (2) the resource being tracked by the parasite is widespread among many host species. We investigated the effect of ecological fitting on structuring the platyhelminth communities of anurans from a temperate forest and grassland in the United States and tropical dry and wet forests …


Aintegumenta Contributes To Organ Polarity And Regulates Growth Of Lateral Organs In Combination With Yabby Genes, Staci Nole-Wilson, Beth A. Krizek Jul 2006

Aintegumenta Contributes To Organ Polarity And Regulates Growth Of Lateral Organs In Combination With Yabby Genes, Staci Nole-Wilson, Beth A. Krizek

Faculty Publications

Lateral organs in flowering plants display polarity along their adaxial-abaxial axis with distinct cell types forming at different positions along this axis. Members of three classes of transcription factors in Arabidopsis (Arabidopsis thaliana; the Class III homeodomain/leucine zipper [HD-ZIP] proteins, KANADI proteins, and YABBY proteins) are expressed in either the adaxial or abaxial domain of organ primordia where they confer these respective identities. Little is known about the factors that act upstream of these polarity-determining genes to regulate their expression. We have investigated the relationship between AINTEGUMENTA (ANT), a gene that promotes initiation and growth of lateral …


Evidence For Absence Of Latch-Bridge Formation In Muscular Saphenous Arteries, Shaojie Han, John E. Speich, Thomas J. Eddinger, Krystina M. Berg, Amy S. Miner, Chris Call, Paul H. Ratz Jul 2006

Evidence For Absence Of Latch-Bridge Formation In Muscular Saphenous Arteries, Shaojie Han, John E. Speich, Thomas J. Eddinger, Krystina M. Berg, Amy S. Miner, Chris Call, Paul H. Ratz

Biological Sciences Faculty Research and Publications

Large-diameter elastic arteries can produce strong contractions indefinitely at a high-energy economy by the formation of latch bridges. Whether ownstream blood vessels also use latch bridges remains unknown. The zero-pressure medial thickness and lumen diameter of rabbit saphenous artery (SA), a muscular branch of the elastic femoral artery (FA), were, respectively, approximately twofold and half-fold that of the FA. In isolated FA and SA rings, KCl rapidly (s) caused strong increases in isometric stress (1.2 x 105 N/m2) and intracellular Ca2+ concentration ([Ca2+]i; 250 nM). By 10 min, [Ca2+]i declined …


Stress Responses In Tropical Sparrows: Comparing Tropical And Temperate Zonotrichia, Haruka Wada, Ignacio T. Moore, Creagh W. Breuner, John C. Wingfield Jul 2006

Stress Responses In Tropical Sparrows: Comparing Tropical And Temperate Zonotrichia, Haruka Wada, Ignacio T. Moore, Creagh W. Breuner, John C. Wingfield

Biological Sciences Faculty Publications

Seasonal modulation of the adrenocortical response appears to be ubiquitous in mid- to high- latitude vertebrates but has not been investigated in tropical vertebrates. Previous studies demonstrate that temperate passerines show seasonality in corticosterone secretion and corticosteroid binding globulin capacities. We examined seasonal and sex differences in the stress response in an equatorial population of Zonotrichia capensis, the only Zonotrichia that breeds in the tropics, and compared the results with those of northern Zonotrichia. Seasonal differences in tropical Zonotrichia would presumably be independent of photoperiod and thus directly related to such activities as reproduction and feather molt. In addition, we …


Linking Scales In Stream Ecology, Winsor H. Lowe, Gene E. Likens, Mary E. Power Jul 2006

Linking Scales In Stream Ecology, Winsor H. Lowe, Gene E. Likens, Mary E. Power

Biological Sciences Faculty Publications

The hierarchical structure of natural systems can be useful in designing ecological studies that are informative at multiple spatial scales. Although stream systems have long been recognized as having a hierarchical spatial structure, there is a need for more empirical research that exploits this structure to generate an understanding of population biology, community ecology, and species-ecosystem linkages across spatial scales. We review studies that link pattern and process across multiple scales of stream-habitat organization, highlighting the insight derived from this multiscale approach and the role that mechanistic hypotheses play in its successful application. We also describe afrontier in stream research …


Facilitation By Pinus Flexilis During Succession: A Hierarchy Of Mechanisms Benefits Other Plant Species, Dayna Baumeister, Ragan M. Callaway Jul 2006

Facilitation By Pinus Flexilis During Succession: A Hierarchy Of Mechanisms Benefits Other Plant Species, Dayna Baumeister, Ragan M. Callaway

Biological Sciences Faculty Publications

Studies of facilitation have primarily been limited to single mechanisms, species, or environments. We examined interacting mechanisms governing the facilitative effects of Pinus flexilis on two later successional understory species, Pseudotsuga menziesii and Ribes cereum, in different microhabitats and seasons at the ecotone between the Rocky Mountain forests and Great Plains grasslands in Montana, USA. In field surveys, 69% of Pseudotsuga and 91% of Ribes were located beneath P. flexilis even though P. flexilis subcrowns accounted for a small proportion of available habitat. For three years, we monitored the survival of Pseudotsuga and Ribes seedlings experimentally planted beneath …


Estimating Detection Probablities Of River Birds Using Double Surveys, Robert J. Fletcher Jr., Richard L. Hutto Jul 2006

Estimating Detection Probablities Of River Birds Using Double Surveys, Robert J. Fletcher Jr., Richard L. Hutto

Biological Sciences Faculty Publications

We describe a method for surveying birds in river habitats that allows for rapid assessment across broad spatial scales and estimation of detection probabilities. Our river survey approach incorporates a double-survey technique, whereby observers in two canoes simultaneously survey birds along a river reach. Data are in the form of a two-sample mark-recapture history, and covariates suspected of influencing detection probabilities can be included in the modeling process and evaluated using information-theoretic approaches. We provide an example using the method along the Madison and upper Missouri rivers in Montana. Overall, detection probabilities for each observer ranged from 57% to 89%, …


Exposure Of Nervous System Cells To Polychlorinated Biphenyls (Pcbs), Results In Alterations Of Neurotrophic Factor Expression, Gordon H. Gurley Jul 2006

Exposure Of Nervous System Cells To Polychlorinated Biphenyls (Pcbs), Results In Alterations Of Neurotrophic Factor Expression, Gordon H. Gurley

Dissertations

Toxic insult by PCBs results in learning and memory deficits in humans. Alterations in expression of neurotrophic factors (NF) and/or their receptors have been linked to changes in learning and memory. How PCBs affect cognition is not known. We suggest that PCBs affect cognition by altering NF expression.

We exposed cultured C6 rat glioblastoma cells (an astrocyte cell-line) to medium containing PCB (Aroclor 1254 (10ppm)). Control cells were treated with dimethyl sulfoxide (DMSO) or regular medium. Enzyme-linked immunosorbent assays (ELISA) were used to determine glial cell-line derived neurotrophic factor(GDNF) and nerve growth factor (NGF) concentrations in all samples. We also …


Molecular Analysis Of The Effects Of Atrazine On Xenopus Laevis Frogs, Ronald Edward Celestine Jul 2006

Molecular Analysis Of The Effects Of Atrazine On Xenopus Laevis Frogs, Ronald Edward Celestine

Dissertations

Atrazine, the most commonly used herbicide in the U.S., has been implicated as one of the factors that may be causing the worldwide decline of amphibians. First, I examined effects of atrazine on laboratory raised Xenopus laevis tadpoles, treated from 5 days post fertilization to NF stage 65/66 with a concentrationof 25 ppb of atrazine. This study showed no significant difference in body weight, length and metamorphic rate.

Second, I used DNA microarrays to examine mRNA expression levels of genes in atrazine treated and control Xenopus laevis tadpoles. I found significant changes in gene expression levels of 18 genes. These …


Where Has All The Leaf Litter Gone?...., Charlotte Buehler, Chad Byers, Summer Drake Jul 2006

Where Has All The Leaf Litter Gone?...., Charlotte Buehler, Chad Byers, Summer Drake

Annual Student Research Poster Session

What Affects the Amount of Leaf Litter in a Forest?
Decomposition rates of leaf litter?
Abiotic soil conditions (pH, calcium content, other nutrients)?
Abundance of earthworms?
Abundance of millipedes?
Abundance of macroinvertebrates (beetles, crickets, spiders)?
Forest composition (maples, oaks, elms)?
Other abiotic factors (microclimate, microtopography, moisture)?
Leaf chemistry (tannin content, lability, recalcitrance)?
Other biotic factors (bacteria, fungi, mycorrhizae)?


The Effect Of Male Competition On Female Choice In Brandt’S Vole, Lasiopodomys Brandti, Jianjun Zhang, Dazhao Shi, Lixing Sun Jun 2006

The Effect Of Male Competition On Female Choice In Brandt’S Vole, Lasiopodomys Brandti, Jianjun Zhang, Dazhao Shi, Lixing Sun

All Faculty Scholarship for the College of the Sciences

The effect of male competition on female choice in the Brandt’s vole (Lasiopodomys brandti) was studied in the laboratory. Using a two-way choice test, we showed that when males did not compete, estrous females preferred and mated with the dominant males, but non-estrous females preferred subordinate males. However, when males competed, all dominant males gained the priority to mate, and the amicable behaviour between males, regardless of their dominant status, and between non-estrous females increased, compared with the behaviour between males and the estrous females. These results showed that interactions among Brandt’s voles were not only influenced by …


Vertical Migration Of The Toxic Dinoflagellate Karenia Brevis And The Impact On Ocean Optical Properties, Oscar Schofield, John Kerfoot, Kevin Mahoney, Mark A. Moline, Matthew Oliver, Steven Lohrenz, Gary Kirkpatrick Jun 2006

Vertical Migration Of The Toxic Dinoflagellate Karenia Brevis And The Impact On Ocean Optical Properties, Oscar Schofield, John Kerfoot, Kevin Mahoney, Mark A. Moline, Matthew Oliver, Steven Lohrenz, Gary Kirkpatrick

Biological Sciences

Vertical migration behavior is found in many harmful algal blooms; however, the corresponding impact on ocean optical properties has not been quantified. A near-monospecific population of the dinoflagellate Karenia brevis was encountered off the west coast of Florida. The community was tracked for 24 hours by following a Lagrangian drifter deployed at the beginning of the experiment. A suite of inherent optical and cellular measurements was made. Over the 24 hour period, the K. brevis population increased during the day with concentrations peaking in the late afternoon (1600 local daylight time) in the upper 2 m of the water column. …


Genetic And Maternal Determinants Of Effective Dispersal: The Effect Of Sire Genotype And Size At Birth In Side-Blotched Lizards, Barry Sinervo, Ryan Calsbeek, Tosha Comendant, Christiaan Both Jun 2006

Genetic And Maternal Determinants Of Effective Dispersal: The Effect Of Sire Genotype And Size At Birth In Side-Blotched Lizards, Barry Sinervo, Ryan Calsbeek, Tosha Comendant, Christiaan Both

Dartmouth Scholarship

We assessed genetic factors on progeny dispersal due to sire color morph genotypes in a field pedigree and lab crosses, and we measured maternal effects by studying both natural and experimentally induced egg size variation. Progeny were released into nature upon hatching, but we recorded dispersal distance at maturity, which reflects effective dispersal after viability selection has run its course. Progeny dispersal was significantly affected by sire genotype. Progeny from orange sires dispersed the farthest. Progeny from blue sires dispersed intermediate distances. Progeny from yellow sires were the most philopatric. Sire genotype effects interacted with egg size. In particular, enlarged …


Environmental Signals Generate A Differential And Coordinated Expression Of The Heme Receptor Gene Family Of Bartonella Quintana, James M. Battisti, Kate N. Sappington, Laura S, Smitherman, Nermi L. Parrow, Michael F. Minnick Jun 2006

Environmental Signals Generate A Differential And Coordinated Expression Of The Heme Receptor Gene Family Of Bartonella Quintana, James M. Battisti, Kate N. Sappington, Laura S, Smitherman, Nermi L. Parrow, Michael F. Minnick

Biological Sciences Faculty Publications

Of all bacteria, Bartonella quintana has the highest reported in vitro hemin requirement, yet an explanation for this remains elusive. To produce diseases such as trench fever, endocarditis, and bacillary angiomatosis, B. quintana must survive and replicate in the disparate environments of the Pediculus humanus corporis (body louse) gut and the human vasculature. We previously identified a five-member family of hemin binding proteins (Hbps) synthesized by B. quintana that bind hemin on the outer surface but share no similarity to known bacterial heme receptors. In the present study, we examine the transcription, regulation, and synthesis of this virulence factor family …


Role Of The Stable Signal Peptide And Cytoplasmic Domain Of G2 In Regulating Intracellular Transport Of The Junín Virus Envelope Glycoprotein Complex, Sudhakar S. Agnihothram, Joanne York, Jack H. Nunberg Jun 2006

Role Of The Stable Signal Peptide And Cytoplasmic Domain Of G2 In Regulating Intracellular Transport Of The Junín Virus Envelope Glycoprotein Complex, Sudhakar S. Agnihothram, Joanne York, Jack H. Nunberg

Biological Sciences Faculty Publications

Enveloped viruses utilize the membranous compartments of the host cell for the assembly and budding of new virion particles. In this report, we have investigated the biogenesis and trafficking of the envelope glycoprotein (GP-Q of the Junin arenavirus. The mature GP-C complex is unusual in that it retains a stable signal peptide (SSP) as an essential component in association with the typical receptor-binding (G1) and transmembrane fusion (G2) subunits. We demonstrate that, in the absence of SSP, the G1-G2 precursor is restricted to the endoplasmic reticulum (ER). This constraint is relieved by coexpression of SSP in trans, allowing transit of …


Avian Affairs: A Study Of The Occurrence And Benefits Of Extra-Pair Breeding Behavior In Eastern Kingbirds (Tyrannus Tyrannus), Amy Catherine Dolan Jun 2006

Avian Affairs: A Study Of The Occurrence And Benefits Of Extra-Pair Breeding Behavior In Eastern Kingbirds (Tyrannus Tyrannus), Amy Catherine Dolan

Dissertations and Theses

Over three consecutive breeding seasons I examined the breeding system of Eastern Kingbirds in Malheur National Wildlife Refuge in SE, Oregon. To assess genetic paternity, I optimized seven microsatellite markers and determined that extra pair paternity was common. Extra-pair young were present in approximately 60% of nests, representing 47% of young. I examined implications of extra-pair paternity from three perspectives.

First, I examined the impact of extra-pair paternity on the opportunity for sexual selection within a socially monogamous system and identified correlates of male reproductive success. Some males were successful at the expense of others, and 24% of males did …


Growth, Feeding And Reproduction Of The Catfish Eremophilus Mutisii (Pisces : Trichomycteridae), From Artificial Reservoirs In Colombia, Gabriel Pinilla, Maritza Abril, Esperanza González Jun 2006

Growth, Feeding And Reproduction Of The Catfish Eremophilus Mutisii (Pisces : Trichomycteridae), From Artificial Reservoirs In Colombia, Gabriel Pinilla, Maritza Abril, Esperanza González

Faculty Publications

The catfish, Eremophilus mutisii, was cultured under different densities in artificial rainfall reservoirs at Caldas, Boyaca, Colombia. At capture, the average total length of the animals was 10 cm and the weight ranged between 9 and 10 g. These fish were in initial stages of sexual development. After a year in the reservoirs, they had increased in length and weight as follows (densities in parentheses): 5.22 cm and 27.23 g (0.5 individuals/m(2))); 1.98 cm and 8.79 g (1 individual/m(2)), and 2.45 cm and 0.82 g (2 individuals/m(2)). They were at the early stages of sexual maturity, and their condition …


The Environmental Impact Of Dietary Choice And Agriculture In California, Harold J. Marlow Jr. Jun 2006

The Environmental Impact Of Dietary Choice And Agriculture In California, Harold J. Marlow Jr.

Loma Linda University Electronic Theses, Dissertations & Projects

Food demand influences agricultural production. Modern agricultural practices have resulted in polluted soil, air and water, eroded soil, dependence on imported oil, and loss of biodiversity. The goal of this research is to investigate the environmental impact of pesticide and fertilizer application, water consumption, and energy used to produce commodities for a vegetarian and non vegetarian diet in California. The working assumption is that greater number and amount of inputs are associated with greater environmental impact. The literature supports this notion. To accomplish this goal, dietary preferences were quantified using the Adventist Health Study and state agricultural data were collected …


Analysis Of An Sirs Age-Structured Epidemic Model With Vaccination And Vertical Transmission Of Disease, Mohammed El-Doma Jun 2006

Analysis Of An Sirs Age-Structured Epidemic Model With Vaccination And Vertical Transmission Of Disease, Mohammed El-Doma

Applications and Applied Mathematics: An International Journal (AAM)

An SIRS age-structured epidemic model for a vertically as well as horizontally transmitted disease under vaccination is investigated when the fertility, mortality and removal rates depend on age and the force of infection of proportionate mixing assumption type, and vaccination wanes over time. We prove the existence and uniqueness of solution to the model equations, and show that solutions of the model equations depend continuously on the initial age-distributions. Furthermore, we determine the steady states and obtain an explicitly computable threshold condition, in terms of the demographic and epidemiological parameters of the model; we then study the stability of the …


Remarks On The Stability Of Some Size-Structured Population Models I: Changes In Vital Rates Due To Population Only, Mohammed El-Doma Jun 2006

Remarks On The Stability Of Some Size-Structured Population Models I: Changes In Vital Rates Due To Population Only, Mohammed El-Doma

Applications and Applied Mathematics: An International Journal (AAM)

We consider a size-structured population model that has been studied in Calsina et al. (2003). We propose a different approach that provides direct stability results, and we correct a stability result given therein. In addition, we obtain global stability results that have not been given in Calsina et al. (2003).


Coexistence Of The Niche And Neutral Perspectives In Community Ecology, Mathew A. Leibold, Mark A. Mcpeek Jun 2006

Coexistence Of The Niche And Neutral Perspectives In Community Ecology, Mathew A. Leibold, Mark A. Mcpeek

Dartmouth Scholarship

The neutral theory for community structure and biodiversity is dependent on the assumption that species are equivalent to each other in all important ecological respects. We explore what this concept of equivalence means in ecological communities, how such species may arise evolutionarily, and how the possibility of ecological equivalents relates to previous ideas about niche differentiation. We also show that the co-occurrence of ecologically similar or equivalent species is not incompatible with niche theory as has been supposed, because niche relations can sometimes favor coexistence of similar species. We argue that both evolutionary and ecological processes operate to promote the …


Analysis Of Abalone (Haliotis Discus Hannai And Haliotis Tuberculata) Shellfish Histology And Pathology Using Microscopic And Molecular Methods, Leanne Harris Jun 2006

Analysis Of Abalone (Haliotis Discus Hannai And Haliotis Tuberculata) Shellfish Histology And Pathology Using Microscopic And Molecular Methods, Leanne Harris

Doctoral

The aims of this research project were to study the biology of abalone through a histological characterisation of two species of this shellfish, Haliotis tuberculata and Haliotis discus hannai using both histochemical and immunohistochemical techniques and to develop molecular methods for the detection and quantitation of common shellfish pathogens associated with abalone disease outbreaks. In the first part of this study immunohistochemistry was used to examine cell distribution structural and functional proteins in abalone tissues. Phenotypic antigen expression was analysed in abalone shellfish using an array of antibodies that react with a range of proteins in many different species. In …