On upper bounds for toroidal mosaic numbers

In this paper, we construct mosaic representations of knots on the torus, rather than in the plane. This consists of a particular choice of the ambient group $\mathbb{A }$ , as well as different Definitions of contiguous and suitably connected. We present conditions under which mosaic numbers might decrease by this projection, and present a tool (called waste) to measure this reduction. We show that the order of edge identification in construction of the torus sometimes yields different resultant knots from a given mosaic when reversed. Additionally, in the Appendix we give the catalog of all torus $2$ -mosaics.     

Control of Nanoscale Environment to Improve Stability of Immobilized Proteins on Diamond Surfaces

Immunoassays for detection of bacterial pathogens rely on the selectivity and stability of bio-recognition elements such as antibodies tethered to sensor surfaces. The search for novel surfaces that improve the stability of biomolecules and assay performance has been pursued for a long time. However, the anticipated improvements in stability have not been realized in practice under physiological conditions because the surface functionalization layers on commonly used substrates, silica and gold, are themselves unstable on time scales of days. In this paper, we show that covalent linking of antibodies to diamond surfaces leads to substantial improvements in biological activity of proteins as measured by the ability to selectively capture cells of the pathogenic bacterium Escherichia coli O157:H7 even after exposure to buffer solutions at 37 °C for extended periods of time, approaching 2 weeks. Our results from ELISA, XPS, fluorescence microscopy, and MD simulations suggest that by using highly stable surface chemistry and controlling the nanoscale organization of the antibodies on the surface, it is possible to achieve significant improvements in biological activity and stability. Our findings can be easily extended to functionalization of micro and nanodimensional sensors and structures of biomedical diagnostic and therapeutic interest.     

Preparation and optical properties of a poly(N-vinylcarbazole) material

We report on the photorefractive properties of a stable polymeric material based on the host polymer, poly(N-vinylcarbazole). Two-beam coupling and four-wave mixing experiments were used to measure the performance of devices constructed by sandwiching the material, composed of host, plasticizer, photo-sensitizer, and non-linear optical chromophore, between transparent electrodes. A steady-state diffraction efficiency of 60% and a two-beam coupling gain of 22 cm^–1 in excess of the absorption of 4 cm^–1 were observed at the laser's operating wavelength of 670 nm. The devices are easily prepared and have lifetimes in excess of one year with no indication of degradation when stored at ambient temperatures.     

Fabrication and finite element modeling of ellipsoidal macro-shells

Millimeter-sized composite spherical shells have long been used in syntactic foams for deep sea buoyancy applications. Recent advances in the understanding of particle settling behavior have revealed the enhanced packing factor of non-spherical shapes, especially of ellipsoidal geometries. In order to realize the packing advantage of ellipsoidal composite shells in syntactic foams, the potential mechanical property penalty as compared with spherical shells must be understood. The current investigation used linear elastic finite element models of isostatic compression to elucidate the mechanical difference between volumetrically identical spherical and ellipsoidal macro-shells. Experimental fabrication of glass-fiber/epoxy composite ellipsoidal macro-shells was also performed in order to verify the viability of the current industrial production process for non-spherical geometries. The relevant trends of increasing predicted stresses with increased deviation from sphericity are discussed, and their implications for syntactic foam properties and applications are discussed.     

DNA-modified nanocrystalline diamond thin-films as stable,biologically active substrates

Diamond, because of its electrical and chemical properties, may be a suitable material for integrated sensing and signal processing. But methods to control chemical or biological modifications on diamond surfaces have not been established. Here, we show that nanocrystalline diamond thin-films covalently modified with DNA oligonucleotides provide an extremely stable, highly selective platform in subsequent surface hybridization processes. We used a photochemical modification scheme to chemically modify clean, H-terminated nanocrystalline diamond surfaces grown on silicon substrates, producing a homogeneous layer of amine groups that serve as sites for DNA attachment. After linking DNA to the amine groups, hybridization reactions with fluorescently tagged complementary and non-complementary oligonucleotides showed no detectable non-specific adsorption, with extremely good selectivity between matched and mismatched sequences. Comparison of DNA-modified ultra-nanocrystalline diamond films with other commonly used surfaces for biological modification, such as gold, silicon, glass and glassy carbon, showed that diamond is unique in its ability to achieve very high stability and sensitivity while also being compatible with microelectronics processing technologies. These results suggest that diamond thin-films may be a nearly ideal substrate for integration of microelectronics with biological modification and sensing.     

RELATIONS BETWEEN ALTERED STREAMFLOW VARIABILITY AND FISH ASSEMBLAGES IN EASTERN USA STREAMS

Although altered streamflow has been implicated as a major factor affecting fish assemblages, understanding the extent of streamflow alteration has required quantifying attributes of the natural flow regime. We used predictive models to quantify deviation from expected natural streamflow variability for streams in the eastern USA. Sites with >25% change in mean daily streamflow variability compared with what would be expected in a minimally disturbed environment were defined as having altered streamflow variability, based on the 10th and 90th percentiles of the distribution of streamflow variability at 1279 hydrological reference sites. We also used predictive models to assess fish assemblage condition and native species loss based on the proportion of expected native fish species that were observed. Of the 97 sites, 49 (50.5%) were classified as altered with reduced streamflow variability, whereas no sites had increased streamflow variability. Reduced streamflow variability was related to a 35% loss in native fish species, on average, and a >50% loss of species with a preference for riffle habitats. Conditional probability analysis indicated that the probability of fish assemblage impairment increased as the severity of altered streamflow variability increased. Reservoir storage capacity and wastewater discharges were important predictors of reduced streamflow variability as revealed by random forest analysis. Management and conservation of streams will require careful consideration of natural streamflow variation and potential factors contributing to altered streamflow within the entire watershed to limit the loss of critical stream habitats and fish species uniquely adapted to live in those habitats. Published in 2011 by John Wiley & Sons, Ltd.     

Differences in the effect of patients' socioeconomic status on the use of invasive cardiovascular procedures across health insurance categories

OBJECTIVES: This study evaluated the effect of patients' socioeconomic status on use of coronary angiography, bypass grafting, and angioplasty across health insurance categories. METHODS: Multiple logistic regression was used to compute the odds of receiving each procedure among 206 233 ischemic heart disease patients residing in urban California zip codes from 1991 through 1993. RESULTS: Residents of high socioeconomic status areas were more likely (odds ratios [ORs] = 1.20-1.41) and residents of low socioeconomic status areas were less likely (ORs = 0.79-0.84) than residents of middle socioeconomic status areas to undergo each procedure. These effects were common among Medicare and health maintenance organization patients and uncommon for privately insured and uninsured patients. CONCLUSIONS: The effect of socioeconomic status varies across health insurance categories.     

An epidermal papilloma of the Atlantic salmon I: Epizootiology, pathology and immunology

Papillomatosis of Atlantic Salmon (Salmo salar) was studied with regard to epizootiology, gross and histologic pathology, and host response. It was found to be a condition of parr in their second summer, but also occasionally of young adult fish (smolts and grilse) which have adapted to salt water. The lesion was plaque-like to papillomatous and consisted of stratified squamous epithelium with supporting stroma. Immunologic findings tended to support histologic observations that the lesion was ultimately sloughed as a result of a cell mediate immune response.