Ultrastructural Study of the Nuclei in Premitotic and Repair DNA Synthesis Following UVB Injury

Ultrastructural changes in nuclei synthesizing DNA were studied by cytochemical technique. Guinea pig ears were UVB irradiated and TdR-H3 was injected intradermally into the irradiated sites 1 hr before biopsy. Areas of the epidermis containing more than 80% of cells in DNA (repair or premitotic) synthesis identified by light microscopic autoradiography were selected and cut at 600 Å. The glycolmethacrylate sections were stained with uranyl acetate and lead citrate, and consecutive sections were incubated with 0.01% pronase and 0.5% RNase before staining in order to observe DNA. In cells undergoing DNA repair, the zone of DNA became discontinuous and DNA was scattered throughout the entire karyoplasm as small aggregates and fine filaments. Nuclei in S-phase showed essentially the same change, but quantitatively the disappearance of DNA from the nuclear membrane and distribution in the karyoplasm became much greater. These changes were not seen in specimens treated without cytochemical technique

Identification and characterization of the Rose Rosette disease causal agent

Rose rosette disease is lethal to multiflora rose, a noxious weed occurring in pastureland in most of Iowa. The potential use of rose rosette disease as a biocontrol agent can be enhanced by grafting infected shoots onto plants in established stands (i.e., augmentation). However, questions arose about whether the disease could be spread to ornamental roses. This study probes the identity of the causal agent for the disease in hopes of determining whether fears of transmission to ornamental roses were valid

Characterization of the Rose Rosette Disease causal agent: potential for biological control and multiflora rose

Rosa multiflora (multiflora rose), introduced to America from Japan for ornamental pur­poses 200 years ago, was promoted in Iowa during the mid-1930s as a living fence that would help to conserve soil and provide cover for wildlife. Multiflora rose has since natural­ized, and today some two million acres of Iowa land are infested with this pest, which renders pastures unusable (dense stands exist in coun­ ties south of a line from West Pottawattamie through Winneshiek, affecting the southeast­ern two-thirds of the state). Cattle avoid the prickly stems, and grass dies beneath its thick growth. Although tillage can control the weed, land in permanent pasture or under the Conser­vation Reserve Program is at risk for the spread of multiflora rose

CFD SIMULATION OF A LIQUID-FLUIDIZED BED OF BINARY PARTICLES

The ability of computational fluid dynamics to predict the expansion and segregation of a binary solids mixture in a liquid-solid fluidized bed is investigated. Unsteady laminar flow is simulated by a modified two-dimensional Eulerian-Eulerian model in Fluent 6.3. The predictions are compared with experimental results for binary particles in the same narrow (1.00-1.18 mm) size range, but with different densities, 1600 and 1900 kg/m3, fluidized by water (1). The voidages and heights of two layers which form, each dominated by one particle species, were found to be sensitive to small changes in particle properties (diameter, density, sphericity), as well as temperature (because of its effect on the water viscosity). As a result, agreement between simulations and experimental results depends on several incompletely characterized factors. Temperature via the water viscosity greatly influences heights and volume fractions of the two layers. Allowing for non-spherical particle shapes is also crucial in reconciling predictions and experimental data

The Bad Truth about Laplace\u27s Transform

Inverting the Laplace transform is a paradigm for exponentially ill-posed problems. For a class of operators, including the Laplace transform, we give forward and inverse formulae that have fast implementations using the fast Fourier transform. These formulae lead easily to regularized inverses whose effects on noise and filtered data can be precisely described. Our results give cogent reasons for the general sense of dread most mathematicians feel about inverting the Laplace transform

Volume Contraction in Liquid Fluidization of Binary Solids Mixtures

When liquid-fluidized particles of radically different sizes and densities mix, the serial (additive volume) model fails to predict the fluidized bed voidage due to contraction of the mixed bed relative to the volumetric sum of the corresponding monocomponent beds. Models are proposed to predict contraction reported in the literature for both upflow and downflow fluidization