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A probabilistic model based methodology has been applied to describe the relative rate of material loss from the steel surface subjected to simultaneous action of high temperature oxidation and mechanical erosion. Growth of the oxide scales is treated deterministically and erosion is described using an established probabilistic modeling methodology. Oxidation is described with a parabolic growth law to quantify the rate of growth of the oxide scales, namely; nickel, iron, and chromium, respectively. In consonance with the published model, erosion is treated using a probabilistic methodology as spatially random phenomena on the oxide surface. The model has been applied to predict the relative erosive loss of material as a function of time resulted as a consequence of influence oxidation on mechanical erosion in a synergetic manner. Keywords: probabilistic modeling, erosion-oxidation interaction, oxidation kinetics, erosion footprint, scale thickness, gamma function, dimensionless variables

Dynamic contrast-enhanced magnetic resonance imaging (DE-MRI) of the tumor blood pool is used to study tumor tissue perfusion. The results are then analyzed using percolation models. Percolation cluster geometry is depicted using the wash-in component of MRI contrast signal intensity. Fractal characteristics are determined for each two-dimensional cluster. The invasion percolation model is used to describe the evolution of the tumor perfusion front. Although tumor perfusion can be depicted rigorously only in three dimensions, two-dimensional cases are used to validate the methodology. It is concluded that the blood perfusion in a two-dimensional tumor vessel network has a fractal structure and that the evolution of the perfusion front can be characterized using invasion percolation. For all the cases studied, the front starts to grow from the periphery of the tumor (where the feeding vessel was assumed to lie) and continues to grow toward the center of the tumor, accounting for the well-documented perfused periphery and necrotic core of the tumor tissue.

Estrogens are thought to regulate female reproductive functions by altering gene transcription in target organs primarily via the nuclear estrogen receptor-[Alpha] (ER-[Alpha]). By using ER-[Alpha] 'knock-out' (ERKO) mice, we demonstrate herein that a catecholestrogen, 4-hydroxyestradiol-17[Beta] (4-OH-[E.sub.2]), and an environmental estrogen, chlordecone (kepone), up-regulate the uterine expression of an estrogen-responsive gene, lactoferrin (LF), independent of ER-[Alpha]. A primary estrogen, estradiol-17[Beta] ([E.sub.2]), did not induce this LF response. An estrogen receptor antagonist, ICI-182,780, or [E.sub.2] failed to inhibit uterine LF gene expression induced by 4-OH-[E.sub.2] or kepone in ERKO mice, which suggests that this estrogen signaling pathway is independent of both ER-[Alpha] and the recently cloned ER-[Beta].4-OH-[E.sub.2], but not [E.sub.2], also stimulated increases in uterine water imbibition and macromolecule uptake in ovariectomized ERKO mice. The results strongly imply the presence of a distinct estrogen-signaling pathway in the mouse uterus that mediates the effects of both physiological and environmental estrogens. This estrogen response pathway will have profound implications for our understanding of the physiology and pathophysiology of female sex steroid hormone actions in target organs.

A study determines the transient response of plate heat exchangers subjected to a step change in the inlet temperature from a uniform state. A dispersion model incorporates the effects of flow maldistribution within and between the channels of the heat exchanger to give better simulation than the conventional plug flow model. A first-order system, or a second order system with a delay period, characterizes the dynamic response. The number of plates and the capacity rate ratio affect the initial delay period and the rise time of the response. Number of transfer units affect the rise time only.

A study shows that cannabinoid ligands act on the preimplantation mouse embryo. Cannabinoid receptors could be used to control possible adverse effects of cannabinoids seen during pregnancy. Normal embryonic development and implantation require regulation of embryonic cAMP and Ca2+ levels through ligand-receptor signaling. The preimplantation mouse embryo contains both brain and spleen type cannabinoid receptor mRNAs.

Marijuana appears to affect the uterus. The psychoactive drug and its cannabinoid derivatives have delta(super 9) tetrahydrocannabinol (THC) as their active component. Adverse effects of these drugs may occur during interactions with uterine cannabinoid receptors. The brain-type cannabinoid receptor (CB1-R) mRNA is expressed in the mouse uterus. THC inhibits forskolin-stimulated cyclic AMP, indicating that the uterine CB1-R is coupled to guanine nucleotide-binding protein.

Clinical trials of a birth control vaccine that contains a heterospecies dimer of the beta subunit of human chorionic gonadotropin and an alpha subunit of ovine luteinizing hormone reveal that this vaccine prevents pregnancies in women. Antibody titers of greater than 50 nanograms per ml are effective in controlling human fertilization while those of less than 35 nanograms per ml cannot control fertility. Antibody response spontaneously declines with time without booster injections and fertility is regained when vaccine concentrations fall below the required concentration.

The expression and regulation of the epidermal growth factor receptor (EGF-R)gene in blastocysts were examined to elucidate the roles of transforming growthfactor-alpha and the EGF-R in embryo implantation. The results showed that dormant blastocysts express low levels of EGF-R. However, upon activation by estradiol-17-beta, the EGF-R mRNA levels increased by eight-fold. These resultsindicate that maternal steroid hormones regulate the expression of EGF-R.