Life Sciences Commons^™

Stress Corrosion And Stress Induced Surface Morphology Of Epitaxial Films, Michael Grinfeld

Scanning Microscopy

In addition to several new predictions, the general theory of thermodynamic stability of heterogeneous systems with rearrangement has allowed us to understand the roots of several experimental and theoretical results of the past. One of them is an outstanding paper of Asaro and Tiller on stress corrosion cracking by surface diffusion published two decades ago. We compare results of Asaro and Tiller with conclusions of thermodynamic theory of solids with rearrangement and develop some Asaro-Tiller results in the directions dictated by the needs of thin films technology and experiment. A surface diffusion model in a prestressed elastic solid is studied …

Utilization Of An Electron-Beam Tester For Determining Internal Electric Field Profiles In Micro-Structured Thin-Film Semiconductor Devices, A. Jank, M. Jung, M. Lambert, G. Lichter, H. Schmoranzer

Scanning Microscopy

An electron-beam tester was used to determine the depth profile of the internal potential distribution in an a-Si:H solar cell and hence the internal electric field profile. The a-Si:H solar cells were prepared for the measurements with the electron-beam tester by low-energy chemical plasma beam etching through a plasma-resistant mask structured by electron-beam lithography. In contrast to an earlier work, the solar cells were in situ illuminated and the electric field profiles were determined for new, degraded and in situ annealed solar cells at various cell temperatures. The measuring results demonstrate that the electron-beam testing technique in combination with a …

Comparative Scanning, Transmission And Atomic Force Microscopy Of The Microtubular Cytoskeleton In Fenestrated Liver Endothelial Cells, Filip Braet, Ronald De Zanger, Wouter Kalle, Anton Raap, Hans Tanke, Eddie Wisse

Scanning Microscopy

Endothelial fenestrae control the exchange of fluids, solutes and particles between the sinusoidal lumen and the microvillous surface of the parenchymal cells. Fenestrae have a critical dimension in the order of 150-200 nm, making it necessary to use microscopes with a resolution better than the light microscope. Comparative whole-mount preparations of isolated, purified and cultured rat liver sinusoidal endothelial cells (LEC) were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Examination of detergent-extracted LEC by SEM and TEM shows an integral cytoskeleton: sieve plates are delineated by a sieve plate-associated cytoskeleton ring and …

Characterizing The Outlines Of Degraded Fine-Particles By Fractal Dimension, Andrew Hunt, David L. Johnson

Scanning Microscopy

Fractal dimension has been used extensively as a descriptor of the rugged outlines of fine-particles. Potentially, it may be a useful parameter for characterizing the outlines of fine-particles which have been subjected to some form of chemical degradation. Here, fractal dimension values have been computed for the outlines of microscopic lead fine-particles both before and after weak hydrochloric acid dissolution experiments. Values obtained for the post-dissolution rugged profiles were greater than those of the pristine fracture grains which had a Euclidean form. The profiles of the degraded fine-particles could be characterized by a single fractal dimension value, or they exhibited …

Recognition And Phagocytosis Of Apoptotic Cells, Luciana Dini, Maria Teresa Ruzittu, Laura Falasca

Scanning Microscopy

Physiological elimination of unwanted cells within the organism occurs via cell death by apoptosis and phagocytosis of these cells represents a key event in the apoptotic process. Macrophages, which are the dedicated phagocytes, and other occasionally phagocytic cells ingest the apoptotic cells while they are still intact, thus preventing the leakage of potentially harmful materials from the dying cells. Although evidence has been presented that the elimination of apoptotic bodies from the tissue operates by means of specific recognition systems, the molecular mechanisms by which an apoptotic cell is recognized are poorly understood. Recent data indicate that phagocyte recognition of …

Scanning Electron Microscopic Study Of The Postnatal Development Of The Rabbit Cochlea, With An Emphasis On Innervation, Hirofumi Morita, Tomoyuki Hoshino, Kunihiro Mizuta, Satoshi Iwasaki

Scanning Microscopy

The development of nerve fiber arrangements of the organ of Corti was studied in rabbits 1, 3, 5, 7 and 12-days-old using thick sections from celloidin-embedded cochleas which were examined under a scanning electron microscope. The arrangements of nerve fibers varied with developmental age. The tunnel spiral bundle was thick and loosely collected in the immature cochlea. The outer spiral fibers were recognized even in the narrow space of Nuel in the one-day-old cochlea. As Nuel's space is extending, the fibers course along the medial side of Deiters' cells. The arrangement of the outer spiral fibers was irregular and sparse …

The Structure Of The G Protein Heterotrimer GIα1Β1Γ2, Mark A. Wall, David E. Coleman, Ethan Lee, Jorge A. Iñiguez-Lluhi, Bruce A. Posner, Alfred G. Gilman, Stephen R. Sprang

Biological Sciences Faculty Publications

The crystallographic structure of the G protein heterotrimer G_iα1(GDP)β₁γ₂ (at 2.3 A) reveals two nonoverlapping regions of contact between α and β, an extended interface between β and nearly all of γ, and limited interaction of α with γ. The major α/β interface covers switch II of α, and GTP-induced rearrangement of switch II causes subunit dissociation during signaling. Alterations in GDP binding in the heterotrimer (compared with α-GDP) explain stabilization of the inactive conformation of α by βγ. Repeated WD motifs in β form a circularized sevenfold β propeller. The conserved cores of these …

Volume Determination Of Human Metaphase Chromosomes By Scanning Force Microscopy, Wolfgang Fritzsche, Eric Henderson

Scanning Microscopy

The scanning force microscope (SFM) yields the topography of the investigated surface. A procedure was developed which starts from this three-dimensional information to estimate the volume of a biological specimen. The volume of spread human metaphase chromosomes was determined in air and rehydrated in aqueous buffer. A difference of the determined volume of a air-dried metaphase chromosome set was found compared to values from electron microscopic investigations, and could be correlated with differences in the hydration state of the chromosomes. SFM-based relative volumes of air-dried chromosomes resembles literature data regarding volume range and distribution. Possible application of SFM-based relative volume …

The Phase Effect In Electronic Stopping: A Survey Of The Contributing Physical Processes, P. Bauer, E. Steinbauer, F. Kastner

Scanning Microscopy

The phase effect in electronic stopping deals with the question whether the energy loss of an ion due to the interaction with electrons depends on the state of aggregation of the target. It is commonly accepted that charge changing collisions of the projectile and changes in the electronic states of the target contribute to the phase effect In addition, the energy loss measurements might possibly be influenced by different impact parameter selection in the two experiments (solid and gas phase). Quantitative results of our calculations show that generally the impact parameter selection inherently present in a transmission experiment is quenched …

Evaluation Of The Surface Changes In Enamel And Dentin Due To Possibility Of Thermal Overheating Induced By Erbium:Yag Laser Radiation, Tat̂Jana Dostálová, Helena Jelíková, Otakar Krejsa, Karel Hamal

Scanning Microscopy

This study investigates the thermal danger of Erbium (Er):YAG laser ablation. Classical preparation techniques have many disadvantages caused by unfavorable changes of temperature, pressure, and by mechanical vibrations. The effect of mechanical vibrations and pressure is eliminated by use of laser ablation technique. The purpose of this study was to analyze the side effects resulting from thermal changes of enamel and dentin in extracted human teeth subjected to pulsed Er:YAG laser radiation using both wet and dry ablation methods.

The micrographs of the sections were checked and measured afterwards. The effect of the investigated laser irradiation on the origin of …

Channel Catfish, Ictalurus Punctatus, T-Lymphocyte Mitogenic Responses To Outer Membrane Proteins And Lps Of The Gram Negative Rod Bacterium, Edwardsiella Ictaluri, Barry Revis Hamilton

Morehead State Theses and Dissertations

A thesis presented to the faculty of the Department of Biological and Environmental Sciences at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Biology by Barry Revis Hamilton on December 8, 1995.

Spatial Dependence Of Electron-Hole Pair Creation In Ion-Solid And Electron-Solid Interactions, F. J. García De Abajo

Scanning Microscopy

The problem of electron excitation induced by interaction of charged particles with solids is investigated on theoretical grounds. The excitation probability is calculated both in homogeneous media and at surfaces. The surface wake potential, needed in the latter, is reviewed. The cases of transmission and aloof geometries are considered separately. Surface plasmons are shown to play a crucial role in the latter. An application to coincidence scanning transmission electron microscopy (STEM) experiments is also discussed. Finally, a spatial representation of the excitation probability is presented.

A Review Of Ministerial Policy Guidelines For Rock Lobster Processing In Western Australia From The Working Group Appointed By The Minister For Fisheries And Chaired By Peter Rich, Peter Rich

Fisheries management papers

The rock lobster processing industry in Western Australia has a long history of management. Whilst management of the industry through the Fisheries Department has obviously been successful in helping to build the rock lobster industry into one of the State's major export industries, this approach is not without problems. With the introduction of the Fisheries Management Act 1994, the Minister for Fisheries deemed it appropriate to appoint an expert group to review the existing regulation of the rock lobster processing sector, draft the necessary guidelines to assist the Executive Director of the Fisheries Department make decisions on rock lobster processing …

Complex Dynamics And Multistability In A Damped Harmonic Oscillator With Delayed Negative Feedback, Sue Ann Campbell, Jacques Bélair, Toru Ohira, John Milton

WM Keck Science Faculty Papers

A center manifold reduction and numerical calculations are used to demonstrate the presence of limit cycles, two-tori, and multistability in the damped harmonic oscillator with delayed negative feedback. This model is the prototype of a mechanical system operating with delayed feedback. Complex dynamics are thus seen to arise in very plausible and commonly occurring mechanical and neuromechanical feedback systems.

Biological Determinism And The Human Genome Project: Is The Past Prologue?, Alexandra Dawn Breen

Theses & Honors Papers

In 1989, The National Institutes of Health, in collaboration with the United States Department of Energy, launched a three billion dollar project that could potentially change the way we view human life. The purpose of the project is to map every gene on every chromosome of the human DNA. The Human Genome Project, as it is referred to, is scheduled for completion by the year 2005. The frank reality of the Human Genome Project is that it will indeed offer some real and measurable benefit to different types of people, including some of those inflicted with fatal diseases and disorders; …

Regulation Of Leukotriene C4 Biosynthesis In Calcium Ionphore A23187-Challeneged August Rat Peritoneal Leukocytes, James M. Huebner

Masters Theses

Leukotriene (LT) C₄ is a potent myotropic product of arachidonic acid 5-lipoxygenation that is thought to play a role in the pathophysiology of immediate hypersensitivity reactions and inflammation. We designed the present study to evaluate the capacity of August (AUG) rat mixed peritoneal leukocytes to generate LTC₄ when challenged with different concentrations of the Ca²⁺ ionophore A23187 and to test the hypothesis that LTC₄ biosynthesis is regulated via a protein kinase C (PKC)-dependent mechanism. The AUG rat, which has a spontaneously high number of peritoneal eosinophils that can be harvested by a simple lavage procedure, is …

Identification Of An Insulin-Responsive Element In The Rat Glucose-6-Phosphate Dehydrogenase Gene, Sheri Lynn Holmen

Masters Theses

The expression of several genes has been shown to be either positively or negatively regulated by insulin at the transcriptional level, however no single insulin responsive DNA element has yet been identified. The transcription factors responsible for stimulation or inhibition of gene expression by insulin also remain to be identified. In recent years, expression of the gene for glucose-6-phosphate dehydrogenase (G6PDH) in primary rat hepatocytes has been found to be influenced by hormones such as insulin, dexamethosone, and glucagon. The molecular mechanism(s) however, underlying hormonal regulation of G6PDH gene transcription remains to be elucidated. The focus of this study was …

Morphometric, Isozyme And Random Amplified Polymorphic Dna (Rapd) : Analysis Of Sarotherodon Mossambicus Populations In Java, Indonesia, Yoedono Sovyanhadi

Loma Linda University Electronic Theses, Dissertations & Projects

The tilapia fish Sarotherodon mossambicus (Teleostei, Cichlidae) is an important protein source for Indonesians, is a strong competitor with some endemic species and .readily hybridizes with other tilapias. A base line assessment of the present genetic diversity of these populations in Indonesia was conducted to facilitate the management of this species. This study compared the effectiveness of the 3 techniques (morphometric, isozyme and RAPD) in revealing differences within and among 9 Javanese populations. The data were also used to estimate the rate of divergence among the populations.

Morphometric analysis showed significant size and shape differences among the populations. Isozyme and …

The Aerobic Metabolism And Behavior Of The Burrow-Dwelling Mantis Shrimp, Hemisquilla Ensigera Californiensis, Jason Jospeh Cassista

Loma Linda University Electronic Theses, Dissertations & Projects

The predatory stomatopod Hemisquilla ensigera californiensiswas captured at 10-20 m depths off California and transferred to an observation tank with artificial burrows similar to those observed in the field. The animals were maintained under a 1OL:140 light-dark cycle and monitored on a 24-hour basis using a time-lapse video recorder. Infrared lamps were used for observations within the burrow and at night. Metabolic rates, as a function of oxygen tension, were measured in respirometry chambers using polarographic oxygen electrodes.

This species is a near complete oxyconformer, so aerobic metabolism is strongly depressed at low oxygen levels, yet the animals remained …

Effect Of Myristicin, A Constituent Of Parsley, On Levels Of Glutathione And Glutathione S-Transferase In Mice Tissues, Maria Theresa Tijerina

Theses and Dissertations - UTB/UTPA

Glutathione (GSH) and related enzymes interact as a ubiquitous and efficient detoxification system in biological organisms. Several naturally occurring, as well as synthetic compounds, are known to increase the levels of glutathione/glutathione S-transferases (GST). One of the natural compounds includes myristicin, which is a constituent of parsley leaf oil as well as other natural foods. The extent to which the levels of the GSH/GST system can be induced appears to be dependent on the specific tissue type and the amount of myristicin administered. Our results show that increased amounts of myristicin exhibited beneficial effects within a certain range for each …

Feeding And Nesting Ecology Of The Great Kiskadee, Pitangus Sulphuratus Texanus (Passeriformes: Tyrannidae) In The Lower Rio Grande Valley, Texas, Robert Luis Gorena

Theses and Dissertations - UTB/UTPA

The foraging and nesting ecology of the Great Kiskadee was studied in the Lower Rio Grande Valley, Texas during 1994 and 1995. Adult kiskadees were found to be omnivorous, feeding mainly on fleshy fruits, fish, and dragonflies, and capturing animal prey mainly by surface gleaning into water or hawking prey out of midair. Nests are constructed mainly during March and April and are built at heights between 6 and 10 meters apparently without preference to tree species. Of 29 nests observed, 66% (19) were active during at least part of the breeding season. Nestlings are fed a diet very similar …

Dna Sequences Involved In The Regulation Of Human C-Myc Gene Expression By Herpes Simplex Virus Type 1 (Hsv-1), Shanli Ye

Dissertations and Theses

The human c-myc gene is a cellular proto-oncogene composed of three exons and two introns. Transcription of c-myc is controlled by two promoters, P1 and P2. The activity of these promoters is regulated by many factors, such as cellular transcription factors E2F, YY1, and HSV-1 immediate-early proteins, ICP0, ICP4.

Many regulatory elements located both upstream of and between P1 and P2 have been identified, and some of these are required for optimum expression of c-myc. In this thesis research, a region downstream from P2 in the c-myc exon 1 was identified by its response to transactivation …

Inter-Alpha-Inhibitor: A Protein Family Involved In The Inhibition Of Calcium Oxalate Crystallization, Fouad Atmani, Jacques Mizon, Saeed R. Khan

Scanning Microscopy

Inter-α-inhibitor (IαI) is a serine protease inhibitor present in human plasma. It has a molecular weight of about 220 kDa which encompasses 3 chains including two heavy chains and one light chain. The light chain, known as bikunin, is responsible for the antitryptic activity of IαI in the inhibition of various enzymes, such as trypsin and chymotrypsin. Under physiologic or certain pathologic circumstances, several macromolecules related to IαI appear in plasma and urine. However, the physiologic role of IαI remains unclear. As far as urolithiasis is concerned, two urinary macromolecules related to IαI have been isolated and shown to be …

In Vivo Metal Substitutions In Metal Sequestering Subcellular Compartments: X-Ray Mapping In Cryosections, A. J. Morgan, C. Winters, A. Yarwood, N. Wilkinson

Scanning Microscopy

Qualitative digital X-ray mapping techniques were employed to determine the distributions of essential and non-essential elements in three invertebrate "models": (1) Pb, Zn, Cd, Cu, Fe in thin cryosections of the hepatopancreas of the terrestrial isopod, Oniscus asellus; (2) Pb, Zn, Cd, Ca in thin cryosections of the chloragogenous tissue of the earthworm, Lumbricus rubellus; and (3) As in air-dried smears and thin cryosections of chloragogen in L. rubellus. Four general conclusions were drawn from the results of these studies: (a) non-essential elements can accumulate, distribute and be compartmentalized because they, or the organo-complexes that they form, …

Mgo·1.5al2o3 Spinel Grain Growth And Microstructure Characterization By Scanning Electron Microscopy And Digital Image Analysis, G. Bonifazi, E. Proverbio

Scanning Microscopy

The microstructure of sintered polycrystalline MgO·1.5Al₂O₃ ceramic is strongly affected by the sintering conditions due to the precipitation of α-alumina at a temperature lower than about 1400°C. Consequently, the mechanical properties, depending on grain size distribution, are greatly influenced. Three different microstructures were obtained by a two step sintering process adopting an intermediate sintering temperature of 1050°C, 1100°C and 1300°C respectively, and a final sintering temperature of 1500°C. Comparable samples obtained directly by firing at 1500°C were used. Digital image analysis (DIA) carried out on scanning electron microscope (SEM) images was performed in order to better describe …

Quantitative Imaging In Electron And Confocal Microscopies For Applications In Biology, N. Bonnet, L. Lucas, D. Ploton

Scanning Microscopy

Among the large number of topics related to the quantification of images in electron and confocal microscopies for applications in biology, we selected four subjects that we consider to be representative of some recent tendencies. The first is the quantification of three-dimensional data sets recorded routinely in scanning confocal microscopy. The second is the quantification of the textural and fractal appearance of images. The two other topics are related to image series, which are more and more often provided by imaging instruments. The first kind of series concerns electron energy-filtered images. We show that the parametric (modelling) approach can be …

Target Geometry Dependence Of Electron Energy Loss Spectra In Scanning Transmission Electron Microscopy (Stem), A. Rivacoba, J. Aizpurura, N. Zabala

Scanning Microscopy

In the frame of the Self-Energy formalism, we study the interaction between STEM electrons and small particles in the range of the valence electron excitations. We first calculate the energy loss probability for an isolated sphere and study the loss spectrum dependence on the size of the particle and on the relative impact parameter. Then we analyze the loss spectra in more realistic situations: (a) the effect of the coupling between the particle and supporting surface is studied in a simple geometrical model; and (b) we analyze the dependence of the losses on the geometrical shape of the target by …

Immunocytes Of The Atlantic Bottlenose Dolphin (Tursiops Truncatus) And West Indian Manatee (Trichechus Manatus Latirostris) : Morphologic Characterizations And Correlations Between Healthy And Disease States Under Free-Ranging And Captive Conditions, Gregory D. Bossart

FIU Electronic Theses and Dissertations

Interest in the health of marine mammals has increased due, in part, to the attention given to human impact on the marine environment. Recent mass strandings of the Atlantic bottlenose dolphin (Tursiops truncatus) and rising mortalities of the endangered Florida manatee (Trichechus manatus latirostris) have raised questions on the extent to which pollution, infectious disease, "stress," and captivity influence the immune system of these animals. This study has provided the first in-depth characterization of immunocytes in the peripheral blood of dolphins (n=180) and manatees (n=56). Immunocyte morphology and baseline values were determined in clinically normal animals …

X-Ray Standing Wave Studies Of Ad-Dimers On Si(001), Y. Qian, P. F. Lyman, M. J. Bedzyk

Scanning Microscopy

X-ray standing waves generated by dynamical Bragg diffraction were used as an element-specific structural probe for investigating Ga and Sb adsorption on Si(001). Using the (004) and (022) reflections, we precisely measured Ga and Sb ad-dimer bond lengths and ad-dimer heights above the bulk-extrapolated Si(001) surface. The room temperature [001] thermal vibration amplitudes of Ga and Sb adatoms on Si(00l) were also directly determined by combining the fundamental (004) and high-order harmonic (008) X-ray standing wave measurements. These high-resolution measurements reveal important quantitative structural information regarding the dimerized surface structures, and provide a stringent test for structural models proposed by …

Enamel Prism Morphology In Molar Teeth Of Small Eutherian Mammals, Elizabeth R. Dumont

Scanning Microscopy

Data summarizing enamel prism shape, sire and spacing are reported for the molar enamel of 55 species of small eutherian mammals including primates, bats, tree shrews, flying lemurs, insectivorans and representatives of a variety of fossil families. Confocal photomicrographs reveal that the subsurface enamel of most species is characterized by arc-shaped prisms. The lack of a clear distinction between pattern 2 and pattern 3 prism configurations within single specimens suggests that the broad category "arc-shaped prisms" is the most appropriate descriptive grouping for these species. Of the total sample, three species exhibit only circular prisms while no evidence of prismatic …