Polarization Light Curve Modeling of Corotating Interaction Regions in the Wind of the Wolf-Rayet Star WR 6

The intriguing WN4b star WR6 has been known to display epoch-dependent spectroscopic, photometric and polarimetric variability for several decades. In this paper, we set out to verify if a simplified analytical model in which Corotating Interaction Regions (CIRs) threading an otherwise spherical wind is able to reproduce the many broadband continuum light curves from the literature with a reasonable set of parameters. We modified the optically thin model we developed in Ignace, St-Louis & Proulx-Giraldeau (2015) to approximately account for multiple scattering and used it to fit 13 separate datasets of this star. By including two CIRs in the wind, we obtained reasonable fits for all datasets with coherent values for the inclination of the rotation axis ($i_0=166^{\circ}$) and for its orientation in the plane of the sky, although in the latter case we obtained two equally acceptable values ($\psi=63^{\circ}$ and $\psi=152^{\circ}$) from the polarimetry. Additional line profile variation simulations using the Sobolev approximation for the line transfer allowed us to eliminate the $\psi=152^{\circ}$ solution. With the adopted configuration ($i_0=166^{\circ}$ and $\psi=63^{\circ}$), we were able to reproduce all datasets relatively well with two CIRs located near the stellar equator and always separated by $\sim 90^{\circ}$ in longitude. The epoch-dependency comes from the fact that these CIRs migrate along the surface of the star. Density contrasts smaller than a factor of two and large opening angles for the CIR ($\beta \geq 35^{\circ}$) were found to best reproduce the type of spectroscopic variability reported in the literature.Comment: 15 pages, 5 figures,5 table

The calculation of per capita phosphorus outputs from detergents in the Lough Erne catchment

Owing to the predominantly rural nature of the Lough Erne Catchment, the contribution of detergent P to the lake is considered to come primarily from domestic sources. The role, form and content of P in such detergents is reviewed, and the significance of its degradation from condensed to orthophosphate forms is discussed

Phosphorus loss at sewage works in the Lough Erne region

Incidental loss of phosphorus (P) in sewage disposal works (SDWs) in the Lough Erne study area is examined through a review of the literature, consideration of operating data from U.K. SDWs and consultation with SDW Managers in Northern Ireland. The number, type and size of SDWs in the region is portrayed cartographically and a summary of each sewage treatment process provided. The literature and SDW operating data show a wide range of Ploss between different treatment processes and between different SDWs of the same type. Northern Ireland figures for P loss appear somewhat lower than those observed elsewhere, varying between 5% and 20% depending on the type of SDW

Micro-circuit reticle fabrication: an investigation of a silver halide emulsion as a portable conformable mask

An investigation of the possibility of spin-coating a silver halide emusion similar to that used on Kodak HRP plates onto a positive resist coating reticle blank was made. By changing the cating weight and temperature of the emulsion it was found that the emulsion could be coated onto the reticle without harm to the positive resist material. A five micron width line was imaged successfully and measured in the final chrome sub-layer of the reticle

Palaeolimnology and lakes with respect to pollution and climate change

The objectives of this INT AS programme between the Environmental Change Research Centre (ECRC), University College London; Institute of Global Climate and Ecology (IGCE) Moscow; Moscow State University (MSU) Department of Hydrobiology; and the Kola Science Centre (KSC) Apatity, are to introduce recently developed palaeolimnological methods to laboratories in the Former Soviet Union and to apply these techniques collaboratively to problems of environmental change and pollution. The focus of this work is centred on atmospheric pollution and potential climate change in the Kola Peninsula and the Lake Baikal region. In the contract year 1995-1996, young scientists from ECRC have visited IGCE and MSU to discuss ideas and the KSC to undertake fieldwork and laboratory analyses of sample material. Senior scientists from IGCE, MSU and KSC have visited ECRC to review the collaborative programme and young scientists from the three participating Russian laboratories have attended courses in numerical analysis and diatom taxonomy at the ECRC. Inevitably the parlous financial situation in Russian academic institutions has affected the progress of this project. The science programme in the Baikal region has been difficult to maintain and the emphasis in 1995-1996 has been placed on the Kola Peninsula. The logistics of fieldwork and laboratory back-up have been easier to arrange with the involvement of KSU, but even here economic difficulties have precluded certain analyses being undertaken. Additionally, as salaries for senior staff and financial support for young scientists have virtually ceased to exist it is inevitable that money for some of the equipment and consumable purchases designated in the original proposal, has been diverted to help maintain the position of key researchers involved with this project. As part of the palaeoecological reconstruction of recent environmental (acidification) and post Holocene climate history of the Kola Peninsula, surface sediments and water samples have been collected from 27 lakes located throughout the Kola Peninsula along the vegetation gradient. Two lakes were subsequently excluded from the training set due to disturbance in the catchments. The final training set thus contains 25 sites. The background to this study and the first results are presented in the scientific report below