Life Sciences Commons^™

Reply By A. Carretero Et Al., Ana Carretero, H. Ditrich, M. Navarro, H. Splechtna, J. Ruberte

Scanning Microscopy

Dear Editor,

The study of vascular casts in the embryo by means of the scanning electron microscope represents the main subject of our research. We fully agree with DeRuiter and Gittenberger-de Groot in that corrosion casting is a valuable tool to study the early angiogenesis in embryos.

Znse Heteroepitaxial Growth On Si (100) And Gaas (100), D. K. Biegelsen, R. D. Bringans, J. E. Northrup, L. -E. Swartz

Scanning Microscopy

The early stages of ZnSe heteroepitaxy on Si(100), Si(100):As and GaAs(100) are compared and contrasted, based on results of scanning tunneling microscopy and photoemission spectroscopy. High Se reactivity with the substrate constituents leads to bulk phase formation which is detrimental to heteroepitaxy. As-termination of Si(100) not only passivates the surface, but also provides an ideal buffer for ZnSe overgrowth. Lacking a similar buffer layer, stoichiometric control of the GaAs(100) surface is investigated to find a means for controlled heteroepitaxy.

Balancing Surface Energy Terms For Stable Growth Of Planar Surfaces, M. Albrecht, P. O. Hansson, S. Christiansen, W. Dorsch, H. P. Strunk, E. Bauser

Scanning Microscopy

We investigate the driving forces that determine the growth mode of heteroepitaxial Ge layers grown from solution on Si substrates with orientations (001), (011) and (111) by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Using liquid phase epitaxy, we can study the influences of strain and surface energy terms independently on effects due to limited surface diffusion. In (001) and (011) orientated layers, {111} faceted islands form (Stranski-Krastanov growth). In contrast, (111) orientated layers grow in a two-dimensional step flow growth mode (Frank-van der Merwe growth).

We model these investigations in terms of energy minimisation considering surface energy …

Recent Surface Studies Using Biassed Secondary Electron Imaging, Rajendra Persaud, Hisato Noro, Muhammad Azim, Robert H. Milne, John A. Venables

Scanning Microscopy

The growth and surface diffusion of Cs on Si(100) and Ag on Fe(110) have been studied using biassed secondary electron imaging (b-SEI) and Auger electron spectroscopy (AES).

The b-SEI technique was found capable of detecting Cs on the Si surface with a 0.5% ML sensitivity. Unusual diffusion profiles containing linear sections were obtained for coverages (θ) < 1/2 ML. The general form of these profiles were reproduced using a 2-phase model, where Cs chains act as sources of mobile adatoms, in conjunction with a diffusion coefficient of the form D ~ θ (1- Cθ). This form of D, obtained from Boltzmann-Matano analysis, is consistent with diffusion theory including strongly repulsive Cs-Cs interactions. An adatom diffusion energy, E_d, = 0.47 ± 0.05 eV was found to be consistent with measurements …

Predicting Relaxation In Strained Epitaxial Layers, R. Beanland, D. J. Dunstan, P. J. Goodhew

Scanning Microscopy

Strained epitaxial semiconductor layers, much thicker than the critical thickness, have been used as "strain-relief" buffer layers for many years. The most successful structure developed so far dates back to the 1960's, and consists of a very thick ( ~30 μm) layer in which the misfit is gradually and continuously increased. These structures relax completely and have a sufficiently low threading dislocation density to allow a device structure to be grown on top. This process requires a very high growth rate to produce the buffer layer in a reasonable time, which is only provided by hydride vapourphase epitaxy. Recently, there …

Agriculture News Release - 1994-12-08b, United States. Congress. House. Committee On Agriculture, E. De La Garza

Kika de la Garza Congressional Papers - Agriculture Committee News Releases

No abstract provided.

Agriculture News Release - 1994-12-08a, United States. Congress. House. Committee On Agriculture, E. De La Garza

Kika de la Garza Congressional Papers - Agriculture Committee News Releases

No abstract provided.

Agriculture News Release - 1994-12-06, United States. Congress. House. Committee On Agriculture, E. De La Garza

Kika de la Garza Congressional Papers - Agriculture Committee News Releases

No abstract provided.

Indicators Of Nutrient Limited Plankton Growth In Lakes Near Mount Saint Helens, Washington, Kurt Davis Carpenter

Dissertations and Theses

Several lakes located in the blast zone of the 1980 eruption of Mount St. Helens were studied to determine if the plankton in the lakes were limited in their growth by nitrogen or phosphorus availability. Long term nutrient enrichment experiments were performed on lake water from five lakes and measures of chlorophyll-a, carbon fixation, and nutrient uptake were used to evaluate the extent of limitation. Nutrient concentrations, ratios, and uptake from 14 lakes provided additional evidence for limitation by nitrogen and/or phosphorus. The physical, chemical, and biological characteristics of the lakes were also examined to monitor the return of these …

New Applications Of The Nuclear Microprobe For Biological Samples, Jan Pallon, Klas Malmqvist

Scanning Microscopy

The continuing development of the Nuclear Microprobe (NMP) has opened up new fields of applications in biology and medicine. Quantitative multielemental analysis in small sections of samples can be performed routinely. The use of techniques such as scanning transmission ion microscopy makes imaging as well as mass normalization possible at submicron resolution. Recent medical applications include studies on thin cryosections prepared from autopsies and biopsies, as well as single cells grown directly on the backing foil used in the NMP analyses. The purpose of the single cell analysis is often pharmacological, e.g., testing of new drugs, their uptake and distribution. …

Daughter Cells Of Saccharomyces Cerevisiae From Old Mothers Display A Reduced Life Span, Nicanor Austriaco, Brian K. Kennedy, Leonard Guarente

Biology Faculty Publications

The yeast Saccharomyces cerevisiae typically divides asymmetrically to give a large mother cell and a smaller daughter cell. As mother cells become old, they enlarge and produce daughter cells that are larger than daughters derived from young mother cells. We found that occasional daughter cells were indistinguishable in size from their mothers, giving rise to a symmetric division. The frequency of symmetric divisions became greater as mother cells aged and reached a maximum occurrence of 30% in mothers undergoing their last cell division. Symmetric divisions occurred similarly in rad9 and ste12 mutants. Strikingly, daughters from old mothers, whether they arose …

Scanning Electron Microscopic Study Of The Collagen Sheath Of The Human Thyroid Gland And Its Disorders, Masao Morita, Takuro Ogata, Keijiro Araki

Scanning Microscopy

A cell-maceration/scanning electron microscope (SEM) method was employed to demonstrate the collagen sheath around follicles (perifollicular sheath) of the human thyroid gland and its disorders. In the normal thyroid gland, the follicles were surrounded by spherical collagen sheaths composed of a framework of thick collagen bands 1-5 μm in width and fine solitary collagen fibrils 50-70 nm in diameter. In benign thyroid diseases (Graves' disease, Hashimoto's thyroiditis and adenomatous goiter), the perifollicular sheaths differed in size and in shape according to the disease, but they were always composed of thick collagen bands and fine fibrils as in the normal thyroid. …

Agriculture News Release - 1994-12-02, United States. Congress. House. Committee On Agriculture, E. De La Garza

Kika de la Garza Congressional Papers - Agriculture Committee News Releases

No abstract provided.

Characterization Of General Esterases From Susceptible And Parathion-Resistant Strains Of The Greenbug (Homoptera: Aphididae), Midori Ono, Jonathan S. Richman, Blair Siegfried

Department of Entomology: Faculty Publications

A susceptible and two parathion-resistant strains of the greenbug, Schizaphis graminum (Rondani), exhibit three different patterns of general esterase isozymes in native polyacrylamide electrophoresis gels. Characterization of general esterase activity using α -naphtholic esters as model substrates indicated that the three strains differed in isozyme composition. The type-I1 strain, which had the highest level of resistance, exhibited the highest levels of general esterase activity under all assay conditions, and the type-I strain had consistently higher levels than the susceptible strain. In all three strains, these esterases were more active toward α -naphtholic esters with side chains of six or fewer …

Isolation Of Three Hexahydro-1,3,5-Trinitro-1,3,5-Triazine- Degrading Species Of The Family Enterobacteriaceae From Nitramine Explosive-Contaminated Soil, Christopher Kitts, Daryl P. Cunningham, Pat J. Unkefer

Biological Sciences

Three species of the family Enterobacteriaceae that biochemically reduced hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were isolated from nitramine explosive-contaminated soil. Two isolates, identified as Morganella morganii and Providencia rettgeri, completely transformed both RDX and the nitroso-RDX reduction intermediates. The third isolate, identified as Citrobacter freundii, partially transformed RDX and generated high concentrations of nitroso-RDX intermediates. All three isolates produced ¹⁴CO₂ from labeled RDX under O₂-depleted culture conditions. While all three isolates transformed HMX, only M. morganii transformed HMX in the presence of RDX.

A Survey Of Source And Finished Water Supplies For Giardia Cysts And Cryptosporidium, Lisa Martin Sexton

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Biology by Lisa Martin Sexton on December 1, 1994.

Tb159: Drought And Cold Stress-Induced Morphometric Changes In Tree Rings Of Red Spruce, Richard Jagels, James Hornbeck, Susan Marden

Technical Bulletins

Morphometric analysis of individual, key growth rings might provide a way of establishing “fingerprints” or unique patterns for growth rings produced following different natural or anthropogenic stresses.

Native Vegetation Handbook For The Shire Of Tammin, Sarah J. Weaving

Native vegetation handbook series

This booklet provides land managers with information relating to the natural resources of the Shire of Tammin including the existing vegetation, drainage systems and soils. Some of the problems relating to the management of natural vegetation resources in the Shire of Tammin and possible solutions to these problems are also discussed. By providing this information it is hoped this booklet will contribute to the long term viability of the agricultural landscape and the conservation of native vegetation within the Shire.

Microcirculation: Electrophysiological Basis For The Response Of Endothelial Cells To Inflammatory Mediators-Bradykinin, Kai Miao

Electronic Theses and Dissertations

Using conventional microelectrodes, I studied the electrical basis for determining the resting V$\sb{\rm m}$ in intact EC's from hamsters. The resting V$\sb{\rm m}$ were found to be $-$40 mV for aortic EC's and $-$43 mV for vena caval EC's. The contributions of ions to the resting V$\sb{\rm m}$ of aortic EC's were compared in terms of the transference number (t$\sb{\rm ion}$). To develop a technique for in situ monitoring changes in V$\sb{\rm m}$ of postcapillary venular EC's in the hamster mesentery, a voltage-sensitive fluorescent probe, bisoxonol, was used to load the cells and the fluorescence signals were analyzed under an …

Number 30 (December 1994), Southern Fishes Council

Southeastern Fishes Council Proceedings

(December 1994) - Notes on the Status and Life History of the Northern Madtom, Noturus stigmosus, in Mississippi. By G.R. Parson, 3 pp.

New Distribution Records of Gulf Slope Drainage Fishes in the Ocmulgee River System, Georgia. By H.L. Bart, et al., 7 pp.

Minutes, Regional Reports, Announcement.

Front Matter, Southeastern Fishes Council

Southeastern Fishes Council Proceedings

No abstract provided.

Minutes - Business Meeting, Southeastern Fishes Council

Southeastern Fishes Council Proceedings

No abstract provided.

Notes On The Status And Life History Of The Northern Madtom, Noturus Stigmosus, In Mississippi, Glenn R. Parsons

Southeastern Fishes Council Proceedings

No abstract provided.

New Distribution Records Of Gulf Slope Drainage Fishes In The Ocmulgee River System, Georgia, Henry L. Bart Jr., Michael S. Taylor, Jeffrey T. Harbaugh, James W. Evans, Steven L. Schleiger, Wayne Clark

Southeastern Fishes Council Proceedings

No abstract provided.

Regional Sfc Reports, Southeastern Fishes Council

Southeastern Fishes Council Proceedings

No abstract provided.

Announcement, Southeastern Fishes Council

Southeastern Fishes Council Proceedings

No abstract provided.

Pb1533-Nipple Watering Systems For Broilers, The University Of Tennessee Agricultural Extension Service

Animals/Livestock

Nipple watering systems for broilers have become very popular in recent years. This is mainly because these systems save labor by eliminating the chore of cleaning waterers. Although labor is greatly reduced with nipple watering systems, this does not mean that they require less management. In fact, nipple waterers demand more time, knowledge and effort to operate properly than do open systems. Problems caused by insufficient or improper management of nipple watering systems can have a serious impact on broiler performance.

Procedures For The Administration And Assessment Of Clearing And Protection Of Native Vegetation In Western Australia, Alexander Mcrae Holm

Soil conservation survey collection

It is Department of Agriculture policy that regulation is only used when all other approaches to address land degradation have failed. Our thrust is to encourage land holders to move towards using land within its capabilities as they continue to adopt sustainable farming systems. Underlying this approach is a self regulatory philosophy with land conservation district committees playing an important management and coordination role. Nevertheless the community expects that land degradation will be controlled and legislation is available to underpin or complement the good intentions of most land holders. The Soil and Land Conservation Act is the legislation used to …

Lupin Logic Number 53

Lupin Logic

Contents

Learning form 1994

- Dry seeding

- Inoculation

- Seed quality

- Weed conrol

- Disease

- Frost

- Growth and yields

Lupinosis vaccine

East coast lupin market

Good quality despite dry season

- Albus

- Angustifolius

Receivals (1 December)

Physical And Optical Properties Of Steam Exploded Laser Printed Paper, Arvind Kumar Sharma

Masters Theses

The main objective of this study was to investigate the effects of steam explosion on the optical properties of recycled fibers, i.e., brightness, opacity, scattering and absorption coefficients, and to find out whether explosive discharge caused fiber damage and affected fiber bonding ability.

Laser printed paper was pulped by the steam explosion process. Addition of two different chemicals, residence time, pressure, and dispersant level were varied during the steam explosion experiments. All factors were kept at two levels.

Full factorial design and regression analysis were applied to determine the effect of different factors on steam explosion pulp. The data indicate …