Variations in the oxygen three-isotope terrestrial fractionation line revealed by an inter-laboratory comparison of silicate mineral analyses

An inter-laboratory comparison of analytical results for the slopes of Terrestrial Fractionation Lines (TFL) measured on a group of quartz and a separate group of garnet samples shows good agreement between laboratories. However, the slopes of the TFL’s for each mineral group differ slightly

The fish populations of the Lower Forth Estuary, including the environmental impact of cooling water extraction

The present study investigated the fish populations of the lower Forth Estuary, east Scotland. Cooling water extraction by the 2400 MW Longannet Power Station (LPS) inevitably removes a certain quantity of fish from the estuary, all of which experience mortality. The present study employed a sampling regime of greater intensity than previous studies to investigate the extent of mortalities from January 1999 - December 2000. Collections of fish impinged on intake screens were made eight times monthly, at LW or HW of spring or neap tides during the day or by night. Marine species dominated the assemblage of fish collected, with sprat, herring, and whiting contributing > 80% of total abundance. Sprat was twice as abundant as herring in 1999, while the proportions were very similar in 2000. Total abundance of all species collected in 1999 was estimated at 1. 09 x 107, while the value of 3.29 x 107 in 2000 was three times larger. These figures were the largest recorded among British estuarine and marine power stations, but were precisely the correct order based on an exponential relationship between total impingement and water abstraction rate established from data from other locations. Validation of the estimated total biomass of fish removed was given by comparison with the known total mass of all materials disposed to landfill. Statistical analysis of impingement data showed that tidal range and season were the most important environmental variables influencing the rate of removal of fish from the estuary. That light was not significant for most species is attributed to high levels of turbidity and the resulting low visibility by day and night. Demersal and benthic fish abundances collected from 1982 - 2000 in 30 annual trawls at three sites in the mid-lower Forth Estuary were analysed. Species tended to be present in greatest abundance at the most seaward of the sites. Patterns of seasonal abundance reflected those observed in the impingement study at LPS, and catches tended to be greatest at L W. Total species richness showed no significant trend over time, whilst total annual abundance of fish captured in trawls showed a significant negative trend. This was largely due to significant declines in the two most abundant species, namely whiting and eel pout, attributable in the latter case to increasing temperatures. Changes in the ichthyofaunal composition were largely driven by whiting, eel pout, cod and plaice. Eight of ten common species showed no significant trend in abundance over the length of the time series, suggesting them to perhaps be at equilibrium densities. Quantities of commercially fished species above minimum landing size limits that were removed by LPS were very low, and restricted to herring and occasional whiting. The quantity of juveniles that could have recruited into the fished populations was expressed as equivalent adults. The values were larger than any previously reported in the UK, primarily due to the quantities of juvenile fish impinged being greater than at any other British power station, and the importance of the Forth as a nursery area for marine species. It was concluded that LPS is the dominant UK power station in terms of magnitude of impingement losses. It may be prudent to consider a precautionary approach to mitigate losses, and to this end options for reduction of the magnitude of impingement are discussed

Study of high altitude plume impingement

Computer program has been developed as analytical tool to predict severity of effects of exhaust of rocket engines on adjacent spacecraft surfaces. Program computes forces, moments, pressures, and heating rates on surfaces immersed in or subjected to exhaust plume environments. Predictions will be useful in design of systems where such problems are anticipated

Trapping and relocating seals from salmonid fish farms in Tasmania, 1990-2000: was it a success?

In an effort to reduce the impact of seals on fish farms, the trapping and relocation of seals at Tasmanian salmonid farms began in 1990. To the end of May 2000,353 identified individual seals had been trapped in 672 capture events. Most were non-breeding male Australian fur seals (Arctocephalus pusillus doriftrus). The number of seals captured increased (from four in 1990 ro a peak of 164 in 1998) with the size and extent of the farms, and an increase in salmon production from 55 tonnes in 1986/87 to almost 10000 tonnes in 1999/2000. Of 586 capture events 52% were of seals that had been captured more than once. When seals are recaptured following trapping and relocation, this occurs on average 25 days after capture. Capture-mark-recapture calculations show that many seals in the vicinity of fish farms are not 'trappable', suggesting that trapping is only effective for certain individuals. Some individuals are recaptured many times, reflecting the predisposition of some individuals to be captured ('trap-happy'). Interaction is seasonal, with most seals trapped during winter, between May and September. The assessment of trends in capture rates is problematic, due to the lack of capture effort information from the farms. A further confounding factor has been the change in management practice both between farms and over time, as the use of predator nets has become more widespread. Two seals trapped at fish farms and fitted with satellite transmitters before relocation have either not returned to the farm or returned to the vicinity of farms and not interacted with them, although on one occasion the individual was trapped. The effectiveness of the relocation program as a management tool to reduce seal interactions cannot be quantified from the relocation data per se, but relocation does not stop seals interacting with farms

Potential Alteration of Analogue Regolith by X-Ray Computed Tomography

The Mars 2020 rover mission will collect and cache samples from the martian surface for possible retrieval and subsequent return to Earth. Mars Returned Samples may provide definitive information about the presence of organic compounds that could shed light on the existence of past or present life on Mars. Post-mission analyses will depend on the development of a set of reliable sample handling and analysis procedures that cover the full range of materials which may or may not contain evidence of past or present martian life [1]

Seasonal abundance of small cladocerans in Lake Mangakaware, Waikato, New Zealand

The seasonal changes in the dynamics and life histories of the Cladocera in Lake Mangakaware, North Island, New Zealand, were studied over 19 months by sampling at weekly or 2-weekly intervals. Lake Mangakaware is a 13.3 ha polymictic lake with high nutrient status, low Secchi disc transparencies, and an unstable thermal regime. The four planktonic cladoceran species (Bosmina longirostris, B. meridionalis, Ceriodaphnia pulchella, and C. dubia) exhibited disjunct population maxima. Only B. longirostris was perennially present. All species exhibited low fecundities and low lipid content, indicating that food resources were limited and that competitive interactions and resistance to starvation were probably important in determining species success. Increases in body size in cooler seasons were unrelated to clutch size, giving further support for the view that available food was limited. These results are consistent with previous experimental findings that subtle differences in life history can determine seasonal success and the outcome of competition between similar species

The Palomar Testbed Interferometer

The Palomar Testbed Interferometer (PTI) is a long-baseline infrared interferometer located at Palomar Observatory, California. It was built as a testbed for interferometric techniques applicable to the Keck Interferometer. First fringes were obtained in July 1995. PTI implements a dual-star architecture, tracking two stars simultaneously for phase referencing and narrow-angle astrometry. The three fixed 40-cm apertures can be combined pair-wise to provide baselines to 110 m. The interferometer actively tracks the white-light fringe using an array detector at 2.2 um and active delay lines with a range of +/- 38 m. Laser metrology of the delay lines allows for servo control, and laser metrology of the complete optical path enables narrow-angle astrometric measurements. The instrument is highly automated, using a multiprocessing computer system for instrument control and sequencing.Comment: ApJ in Press (Jan 99) Fig 1 available from http://huey.jpl.nasa.gov/~bode/ptiPicture.html, revised duging copy edi

Drivers of Human‒wildlife interactions in a co-existence area: a case study of the Ngorongoro conservation area, Tanzania

Communities in Africa bordering national parks or protected areas commonly overlap with wildlife. However, it is unclear to what degree such overlaps result in interactions with wildlife. The Ngorongoro Conservation Area (NCA) was designated a multiple land-use conservation area in 1959. Maasai and Datoga pastoralists and Hadzabe hunter-gatherers reside with protected wildlife in NCA. The study was carried out in four Maasai villages within the NCA, including Kayapus, Endulen, Meshili, and Nainokanoka. A cross-sectional study was used to assess drivers of human‒wildlife interactions using questionnaire surveys, focus group discussions, and field visits. A total of 396 households participated in the survey. The collected data were analysed using qualitative data analysis techniques and descriptive statistics such as frequencies and means. The habitat, which comprises water, pasture, shelter, and space, accounted for 100% of interactions, indicating that it is the primary driver of human‒wildlife conflict. Other driving factors for human‒wildlife interactions are the increase in wildlife, collections of firewood, domestic animals kept, and influence of community sleeping arrangements, searching for traditional medicines, and killing of lions for ritual purposes or defense. Large household sizes (36 family members) coupled with climate change have also driven and fuelled human‒wildlife interactions. Challenges identified as threatening human‒wildlife co-existence are injuries, deaths, disease transmission, and destruction of property. To mitigate human‒wildlife conflicts, the following are recommended: the increase in boarding schools coupled with the increase in enrolment of students in boarding schools or providing reliable transport, distribution of tap water, increasing food assistance to the community living in poverty, controlling population increase through reallocation the population in other areas, introducing zero-grazing, using biogas, discouraging community sleeping arrangements, i.e., humans with calves in the same house, improving record-keeping of the wildlife attacks, provisional dissemination of research findings to the community

Collective Behavior of Asperities in Dry Friction at Small Velocities

We investigate a simple model of dry friction based on extremal dynamics of asperities. At small velocities, correlations develop between the asperities, whose range becomes infinite in the limit of infinitely slow driving, where the system is self-organized critical. This collective phenomenon leads to effective aging of the asperities and results in velocity dependence of the friction force in the form $F\sim 1- \exp(-1/v)$.Comment: 7 pages, 8 figures, revtex, submitted to Phys. Rev.