CONSERVATION OF ENDANGERED ENDEMIC SEABIRDS WITHIN A MULTI‐PREDATOR CONTEXT: THE BARAU'S PETREL IN RÉUNION ISLAND

Abstract Seabirds breeding on islands are vulnerable to introduced predators, such as rats and cats, and the removal of such predators is generally viewed as a priority for seabird conservation and restoration. However, multiple invasive mammal species interacting may generate unexpected outcomes following the removal (eradication) of one species. Generally these indirect interactions are not well understood or demonstrated. We propose and study a prey (seabird)‐mesopredator (rat)‐superpredator (cat) model, taking into account the juvenile stages in the prey population, in order to direct conservation management for seabird conservation. We give a more biologically realistic differential system than those studied before (Courchamp et al. [1999] ; Fan et al. [2005] ), in particular for long‐lived seabird species. We present a theoretical study and show existence and uniqueness of a positive solution as well as a qualitative study of the equilibria that may appear. Because standard numerical methods, usually implemented in scientific softwares, can fail to give the right biological approximations ( Anguelov et al. [2009] ), we propose a reliable algorithm that preserves most of the qualitative properties of the continuous system, using the theory of nonstandard finite difference methods. Finally, we use biologically realistic parameters available for the representative Barau's petrel (Pinet et al. [2008] ), an endemic species from Réunion island, to present numerical simulations that support the theoretical study. Cats play the major role in seabird prey population dynamics. Seasonality in seabird breeding delays but does not prevent extinction. In all scenarios, cat control (or preferably eradication) is imperative to prevent extinction of vulnerable long‐lived seabirds, like the Barau's petrel.     

An ab initio study of vibrational corrections to the electrical properties of the fluoromethanes: CH3F,CH2F2, CHF3 and CF4

Accurate SCF and MP2 quartic property hypersurfaces have been computed for the energy, dipole moments, quadrupole moments and polarizability tensors of the fluorinated methanes CF₄, CHF₃, CH₂F₂ and CH₃F, to establish accurate values of zero-point vibrational corrections to the properties. Using a consistent set of r_e geometries from density functional theory, these ZPVCs are coupled with accurate electrical properties computed using a range of correlated methods, especially BD and BD(T), and a number of purpose-built polarized basis sets, to obtain near definitive estimates of these properties that incorporate the effects of vibrational averaging. Careful attention has been paid to a critical comparison between these theoretical estimates and experimental measurements, and agreement between the two is shown to be exceptionally good. In particular, it is clear that in many instances more precise experimental results would be required in order to discriminate between different correlated results, or between the present results and those which may be obtained with larger basis sets. The work highlights the necessity to allow for the effects of zero-point vibrational averaging when comparing theory with experiment, or even when comparing different theoretical results with one another using experiment as a benchmark. It also points to the need for further precise experimental measurements of some of these properties.     

Current-Cost Deepreciation: Estimation and Optimization

In recent years, current-cost accounting (CCA) has receivedconsiderable attention throughout the Western industrializedworld. However, both in the academic and professional literature,the debate over the utility of CCA has been almost exclusivelyconfined to the theoretical level. The practical issue of obtainingreliable and accurate methods for estimating the various CCAadjustments has been almost totally ignored. In this respect,the present note outlines techniques which may be used to estimatecurrent-cost depreciation. Specifically, using standard techniquesfrom the discipline of numerical mathematics, integration formulaeare derived by which current-cost depreciation may be estimated.It is shown that professional accounting bodies have unknowinglyrecommended use of the simplest Newton-Cotes closed integrationformulae and that more precise estimates may be obtained byemploying higher-level Newton-Cotes rules. Alternatively, Gaussianquadrature methods may be employed, though these have the disadvantageof using unevenly spaced nodes or quadrature points. The paperthen derives optimal current-cost depreciation rules for firmswho, for political reasons, desire to minimize reported profits.It is shown that, at a theoretical level at least, this problemis reduced to one in the calculus of variations.     

NUMBER AND DISTRIBUTION OF CHROMOPHORE TYPES IN NATIVE PHYCOBILIPROTEINS

Abstract— Fluorescence lifetimes and absolute quantum yields of a number of chromatographically pure phycobiliproteins have been determined. In conjunction with absorption, fluorescence emission and polarization spectra, these data were used to calculate the number of different types of chromophore, sensitizing and fluorescing, per chromoprotein.
To characterize the spatial distributions of the chromophores, the observed emission anisotropies were compared with those calculated from models, using the Förster transfer mechanism and the Jablonski 'active sphere' approximation. The experimental values are more consistent with surface locations for the fluorescing chromophores rather than with their distribution throughout the volume.
Theoretical efficiencies of transfer between sensitizing and fluorescing chromophores on the same macromolecule are consistent with those observed. The transfer efficiency from phycoerythrin prosthetic groups to chlorophyll a compared with that for transfer via phycocyanin indicates that the latter process is probably the favoured migration route.     

Wall Region Porosity Distributions for Packed Beds of Uniform Spheres with Modified and Unmodified Walls

A mathematical derivation of the porosity (local void fraction) distribution near the walls of packed beds of uniform spheres is presented. This investigation supports the study of methods of reducing or eliminating the so-called wall effect, or bypass flow, which accompanies the increase in porosity when spheres come in contact with a solid boundary. Limiting the amount of bypass flow is important in certain applications such as in packed bed nuclear reactors where bypass flow allows some coolant to avoid the high power density core region. Four basic porosity distributions are determined. The first investigates the case where spheres against a flat wall are packed in the tightest possible packing density. This density is then reduced by changing the sphere spacing until the minimum porosity matches that obtained experimentally. In the other cases, the effect of various ways of embedding spheres in the wall on the wall region porosity is examined. By partially embedding spheres in the wall, the porosity at the wall is reduced and the most direct cause of the bypass flow is thereby eliminated. The porosity is found by evaluating the ratio of the solid area to total area in a plane which is parallel to the wall. The local porosity is derived as a function of distance from the wall in the region within one-half a sphere diameter from the wall. The average porosity of the wall region is also calculated. This research has application to flow situations such as packed bed chemical reactors, pebble bed nuclear reactors and flow in packed beds.     

Signature Analysis Extended: A System Approach to Machinery Dynamics

Signature analysis has a definite function and role to play in understanding machinery dynamics and maintaining the health of operating systems. It does not, however, provide all the answers. Experimental modal analysis can be used to extend the reach of signature analysis by providing a more fundamental understanding of machinery dynamics. Combined experimental and analytical techniques for system analysis can take a further step in understanding and designing better machinery. These techniques allow the engineer to see how various components or subsystems interact, even before total system hardware is available. They also can provide valuable load information so that better, more efficient component design may be done.
The broad application of system analysis technology is just beginning to take place. Developments in hardware and user-oriented software have taken some of the "black-magic" out of the technology and have made it something that can be used as a routine tool. Many areas are open for development and are actively being pursued. A number of particular interest are:⁵ coupling of equipment dynamics with dynamic fluid forces created in attached piping; continuation of development of techniques for flexible rotor balancing using a system model, modal data base, and future instrumentation developments;⁶ additional refinement techniques for coupling of foundation dynamics with equipment dynamics; additional insight in the use of computerized condition monitoring systems by identifying the optimal locations for instrumentation and insight into the proper monitoring system diagnostics.     

XERODERMA PIGMENTOSUM FIBROBLASTS INCLUDING CELLS FROM XP VARIANTS ARE ABNORMALLY SENSITIVE TO THE MUTAGENIC AND CYTOTOXIC ACTION OF BROAD SPECTRUM SIMULATED SUNLIGHT

Abstract— The cytotoxic and mutagenic effects of broad spectrum simulated sunlight, as delivered by a Westinghouse Sun Lamp FS 20 filtered to eliminate wavelengths below 290 nm, were determined in diploid human skin fibroblasts which differ in their ability to repair pyrimidine dimers, and compared with results obtained with UV 254 nm radiation. The cell strains tested included normal fibroblasts; excision repair-deficient xeroderma pigmentosum (XP) cells from patients XP12BE (complementation group A). XP7BE (group D). and XP2BI (group G): and an XP variant patient (XP4BE) whose cells excise pyrimidinc dimers at a normal rate, but exhibit abnormal replication of DNA containing unexcised lesions. Cytotoxicity was assayed from loss of colony-forming ability. The group A cells were most sensitive to the killing effect of the Sun Lamp; the group D and G cells were slightly less sensitive; the XP variant cells showed intermediate sensitivity; and normal cells were most resistant. When the Sun Lamp survival curves for the group A, group D, the XP variant and normal cells were compared with their respective UV 254 nm survival curves, the relationships between the strains were virtually identical (i. e. the curves were related by a constant fluence modification factor). suggesting a common lesion for cell killing. The marker for mutagenesis was resistance to 6-thioguanine. The group A XP cells proved most sensitive to mutations induced by the simulated sunlight: the variant cells were intermediate; and the normal cells were the most resistant. Again, when the curves for mutations induced in these cell strains by simulated sunlight were compared with their respective 254 nm UV mutation curves, these were related by a constant fluence modification factor. suggesting a common lesion for mutagenesis. These results. taken together with published data indicating that at equicytotoxic levels of UV254 nm radiation and the filtered Sun Lamp. the number of pyrimidine dimers in the DNA of XP12BE cells was equal. support the hypothesis that the dimer is the lesion principally involved in both effects. Our data also support the hypothesis that mutations are involved in the sunlight-induced skin cancer of XP patients.     

Eulerian-Lagrangian localized adjoint methods for convection-diffusion equations and their convergence analysis

We develop and analyze Eulerian-Lagrangian localized adjointmethods (ellam) for convection-diffusion problems. The formulationuses space-time elements, with edges oriented along Lagrangianflow paths, in a time-marching scheme, where space-time testfunctions are chosen to satisfy a local adjoint condition. Thisallows Eulerian-Lagrangian concepts to be applied in a systematicmass-conservative manner to problems with general boundary conditions.In one space dimension with constant velocity, all combinationsof inflow and outflow Dirichlet, Neumann, or flux boundary conditionsare carefully considered, compared and discussed based on bothanalysis and numerical experiments. In some cases, the discreteunknowns include influxes, outfluxes, or resolution of the outflowingsolution finer than the time-step size. Optimal-order errorestimates in all cases and some superconvergence results areobtained. Numerical results show the strong potential of thesemethods and verify the theoretical estimates. Implementationsfor variable-coefficient problems in one and multiple spacedimensions, considered in detail elsewhere, are outlined.     

Spectroscopic, Chromatographic and Visual Investigation of Organic Dyes

An introductory level laboratory experiment is presented in which students learn about color using spectroscopy and chromatography. The pedagogical approach is discovery-based; students are given only enough background information to enable them to take good data. Commercially available dyes are dissolved in water to make concentrated stock solutions, which students then dilute to prepare solutions of primary, secondary and tertiary colors. The class works as a team to study colored solutions representing a range of concentrations and combinations of the three primary colors: cyan, yellow, and magenta. Students record transmission and absorption spectra and compare the results with human perception. They show the number of components in each solution by paper chromatography. They explore the filter nature of dyes, the effects of concentration, and the cumulative effects of mixing dyes. From this information they deduce the principles of color printing.The experiment is best performed with a photodiode array spectrophotometer; alternative approaches include spectrometers and simple spectroscopes which the students make from cereal boxes. The experiment can be performed in either a single three-hour laboratory period, or alternatively, three one-hour sessions.