Interactions Between the Feed and Feeding Environment

This information was presented at the 2016 Cornell Nutrition Conference for Feed Manufacturers, organized by the Department of Animal Science In the College of Agriculture and Life Sciences at Cornell University. Softcover copies of the entire conference proceedings may be purchased at http://ansci.cals.cornell.edu/extension-outreach/adult-extension/dairy-management/order-proceedings-resources

Movements around a tunnel in two-layer ground

An increasing need for accurate predictions of tunnelling-induced ground movements and potential damage to structures has produced a number of publications over the past 30 years. Few, however, have addressed the problem of tunnelling in ground consisting of more than one soil layer or the associated subsurface movements. The aim of the research was to investigate ground movements in two-layer ground conditions, specifically movements above tunnels driven in clay overlain by coarse grained materials. The principal methods of investigation were geotechnical centrifuge model testing and finite element analysis using the 3-Surface Kinematic Hardening (3-SKH) model, an elasto-plastic soil model implemented in the finite element program CRISP at City University, London. Both methods use effective stress path modelling to produce soil behaviour representative of prototype situations. Twenty-eight plane strain centrifuge model tests are reported in which the tunnel was represented by a SOmm diameter cylindrical cavity supported by compressed air pressure. The tunnel cavity was located within a layer of overconsolidated kaolin clay and in most cases the clay had an overlying layer of coarse grained material. The main variables in the tests were: the type of overlying strata; the thicknesses of the two strata; and the position of the water table. Tests were conducted at an acceleration of 1 OOg when the cavity then represented a Sm diameter tunnel with a maximum depth to tunnel axis of 22.Sm at prototype scale. After effective stress equilibrium was achieved, ground movements were generated by reducing the tunnel support pressure at a rate which produced essentially undrained behaviour in the clay. Transducers were used to measure pore pressures in the clay near the tunnel and displacements at the ground surface and at the clay/sand interface. Subsurface movements in the clay were obtained from images from a CCD camera, mounted on the centrifuge swing to view the front of the model in-flight, using a new digital image processing system developed at City University to track targets in the vertical face of the clay. Stress path triaxial tests were performed on some of the sands used in the centrifuge experiments, to determine stiffness properties for analysis of centrifuge test results and input for numerical analyses. Values of shear stiffness at very small strains, G'max, were determine dusing the bender element technique. Finite element analyses were conducted at centrifuge model scale with carefully simulated model stress histories. Some were direct simulations of physical model tests and were fully evaluated by comparison with centrifuge test data. Numerical predictions could be used with confidence, therefore, within the known limitations of the analyses. As well as evaluating the numerical model, the main points of investigation were the effects of: modelling conditions such as boundary proximity and stress history; the constitutive model used for the sand: the stiffness and depth of the upper strata on the movements in the clay. The results are applicable to predicting ground movements in the plane perpendicular to single, long tunnels, and the most important findings of the research are as follows. i) Both surface and subsurface settlement troughs are well represented by Gaussian distributions, except within a vertical distance of approximately O.5D of the tunnel cro\\ n when considerably steeper settlement profiles should be anticipated. ii) The form of the settlement profiles is constant until the tunnel begins to collapse (V-20%). iii)The equations of Mair et al (1993) adequately describe the distributioll of vertical movements with depth for tunnels in clay-only soil profiles, although, near a "free" ground surface the distribution of movements may be considerably wider (also see (i) above). iv) F or tunnels in clay with an overlying layer of different material the ratio of the shear stiffnesses at the interface between the materials should be taken into account. v) For undrained (constant volume) conditions, horizontal displacements may be inferred from the vertical displacements as the vectors of movement focus on the point where the tangent to the distribution of i \vith depth intersects the vertical tunnel axis

Optical calibration hardware for the Sudbury Neutrino Observatory

The optical properties of the Sudbury Neutrino Observatory (SNO) heavy water Cherenkov neutrino detector are measured in situ using a light diffusing sphere ("laserball"). This diffuser is connected to a pulsed nitrogen/dye laser via specially developed underwater optical fibre umbilical cables. The umbilical cables are designed to have a small bending radius, and can be easily adapted for a variety of calibration sources in SNO. The laserball is remotely manipulated to many positions in the D2O and H2O volumes, where data at six different wavelengths are acquired. These data are analysed to determine the absorption and scattering of light in the heavy water and light water, and the angular dependence of the response of the detector's photomultiplier tubes. This paper gives details of the physical properties, construction, and optical characteristics of the laserball and its associated hardware.Comment: 17 pages, 8 figures, submitted to Nucl. Inst. Meth.

Cytotoxicity of cobalt chloride in brain cell lines - a comparison between astrocytoma and neuroblastoma cells

High levels of circulating cobalt ions in blood have been reported to induce systemic reactions in patients with metal-on-metal (MoM) hip implants. We still lack information regarding these adverse effects, which may specifically impact on patients showing adverse neurological symptoms. To investigate this, we used a battery of in vitro viability and proliferation assays to identify toxic cobalt chloride (CoCl 2) concentrations in two different brain cell types: SH-SY5Y neuroblastoma and U-373 astrocytoma cells. Cobalt cytotoxicity was characterised by MTT and Neutral Red (NR) assays at concentrations ranging from 0 to 500 μM after 24, 48, and 72 h exposure. MTT and NR showed a dose- and time-dependent toxicity with cobalt decreasing cell viability at high concentrations. IC50s for MTT at 72 h (astrocytes: 333.15 ± 22.88; neurons: 100.01 ± 5.91 μM) and for BrdU proliferation assays (astrocytes: 212.89 ± 9.84; neurons: 88.86 ± 19.03 μM) demonstrate that SH-SY5Y neurons are significantly more vulnerable to cobalt than astrocytes. Increased BrdU and MTT assay sensitivity suggested that DNA synthesis and metabolism disruption were involved in Co toxicity. Intracellular cobalt level measured by ICP-MS was significant after 100 μM treatment. Astrocytes displayed improved resistance to cobalt toxicity and higher uptake, which may reflect their neuroprotective nature. In summary, exposure to high concentrations of extracellular cobalt has deleterious effects in neurons and astrocytes, with neurons showing particular sensitivity

Ratios of BB and DD Meson Decay Constants in Relativistic Quark Model

We calculate the ratios of $B$ and $D$ meson decay constants by applying the variational method to the relativistic hamiltonian of the heavy meson. We adopt the Gaussian and hydrogen-type trial wave functions, and use six different potentials of the potential model. We obtain reliable results for the ratios, which are similar for different trial wave functions and different potentials. The obtained ratios show the deviation from the nonrelativistic scaling law, and they are in a pretty good agreement with the results of the Lattice calculations.Comment: 13 pages, 1 Postscript figur

Global longitudinal strain is compromised in patients with elevated blood cobalt levels secondary to metal-on-metal hip implants

Metal-on-metal (MoM) hip arthroplasties are known to release metal ions including cobalt into the blood stream. Elevated blood cobalt at levels over 250µg/l have been shown to be a risk factor for developing systemic complications including neurological, endocrine and cardiovascular symptoms. Published case reports document cardiomyopathy, a need for cardiac transplantation and, in some cases, death in patients with severely elevated blood cobalt. Clinical studies have found conflicting evidence of cobalt-induced cardiomyopathy in patients with MoM hips. The extent of cardiovascular injury in patients with elevated blood cobalt levels above 250µg/l has not previously been examined and is the focus of the current study

New directions in island biogeography

Aim: Much of our current understanding of ecological and evolutionary processes comes from island research. With the increasing availability of data on distributions and phylogenetic relationships and new analytical approaches to understanding the processes that shape species distributions and interactions, a re-evaluation of this ever-interesting topic is timely. Location: Islands globally. Methods: We start by arguing that the reasons why island research has achieved so much in the past also apply to the future. We then critically assess the current state of island biogeography, focusing on recent changes in emphasis, including research featured in this special issue of Global Ecology and Biogeography. Finally, we suggest promising themes for the future. We cover both ecological and evolutionary topics, although the greater emphasis on island ecology reflects our own backgrounds and interests. Results: Much ecological theory has been directly or indirectly influenced by research on island biotas. Currently, island biogeography is renascent, with research focusing on, among other things, patterns and processes underlying species interaction networks, species coexistence and the assembly of island communities through ecological and evolutionary time. Continuing island research should provide additional insight into biological invasions and other impacts of human activities, functional diversity and ecosystem functioning, extinction and diversification, species pools and more. Deeper understanding of the similarities and differences between island and mainland systems will aid transferability of island theory to continental regions. Main conclusions: As research in biogeography and related fields expands in new directions, islands continue to provide opportunities for developing insights, both as natural laboratories for ecology and evolution and because of the exceptions islands often present to the usual ‘rules’ of ecology. New data collection initiatives are needed on islands world-wide and should be directed towards filling gaps in our knowledge of within-island distributions of species, as well as the functional traits and phylogenetic relationships of island species