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Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

The mid-Holocene eruption of Aniakchak volcano (Aniakchak II) in southwest Alaska was among the largest eruptions globally in the last 10,000 years (VEI-6). Despite evidence for possible impacts on global climate, the precise age of the eruption is not well-constrained and little is known about regional environmental impacts. A closely spaced sequence of radiocarbon dates at a peatland site over 1000 km from the volcano show that peat accumulation was greatly reduced with a hiatus of approximately 90–120 yr following tephra deposition. During this inferred hiatus no paleoenvironmental data are available but once vegetation returned the flora changed from a Cyperaceae-dominated assemblage to a Poaceae-dominated vegetation cover, suggesting a drier and/or more nutrient-rich ecosystem. Oribatid mites are extremely abundant in the peat at the depth of the ash, and show a longer-term, increasingly wet peat surface across the tephra layer. The radiocarbon sample immediately below the tephra gave a date of 1636–1446 cal yr BC suggesting that the eruption might be younger than previously thought. Our findings suggest that the eruption may have led to a widespread reduction in peatland carbon sequestration and that the impacts on ecosystem functioning were profound and long-lasting.

Field surveys were conducted on 319 sites of the Western Australian grain belt in 2006 to determine the occurrence and distribution of summer fallow weed species. Sites were located across five growing season regions (north, north central, central, south central, and south) and three annual rainfall zones (high, medium, and low). A total of 51 species (or species groups) from 18 families were identified, with the large majority of species (35%) belonging to the Poaceae family. The most prevalent species found, being present at more than 10% of all sites, were wheat, “melons” (weedy watermelon and paddymelon), rigid ryegrass, capeweed, clover, mintweed, wild radish, fleabane, windmill grass, and rolypoly. Correspondence analysis revealed that the north, central, and southern regions of the grain belt could be predominately segregated according to dominant weed species occurrence; however, no segregation by rainfall zone was apparent. This study has given an overview of summer fallow weed occurrence in the Western Australian grain belt and highlights those weed species that are common and yet lack sufficient research into their ecology and management.

Peatlands are widely exploited archives of paleoenvironmental change. We developed and compared multiple transfer functions to infer peatland depth to the water table (DWT) and pH based on testate amoeba (percentages, or presence/absence), bryophyte presence/absence, and vascular plant presence/absence data from sub-alpine peatlands in the SE Swiss Alps in order to 1) compare the performance of single-proxy vs. multi-proxy models and 2) assess the performance of presence/absence models. Bootstrapping cross-validation showing the best performing single-proxy transfer functions for both DWT and pH were those based on bryophytes. The best performing transfer functions overall for DWT were those based on combined testate amoebae percentages, bryophytes and vascular plants; and for pH, those based on testate amoebae and bryophytes. The comparison of DWT and pH inferred from testate amoeba percentages and presence/absence data showed similar general patterns but differences in the magnitude and timing of some shifts. These results show new directions for paleoenvironmental research, 1) suggesting that it is possible to build good-performing transfer functions using presence/absence data, although with some loss of accuracy, and 2) supporting the idea that multi-proxy inference models may improve paleoecological reconstruction. The performance of multi-proxy and single-proxy transfer functions should be further compared in paleoecological data.

A model of the growth and decay of the Antarctic Peninsula Ice Sheet during the last glacial/interglacial cycle is used to identify the main controls on ice sheet behavior. Using as input glaciological assumptions derived by W. F. Budd and I. N. Smith (1982, Annals of Glaciology 3, 42–49), bedrock topography, isostatic compensation, and mass balance relationships, the model is driven by sea-level change over the last 40,000 yr in association with assumed changes in the rate of melting beneath ice shelves. An ice sheet dome over 3.5 km thick grows on the offshore shelf and straits west of the Antarctic Peninsula and reaches a maximum at 18,000 yr B.P. Collapse begins at 14,000 yr B.P. but becomes rapid and continuous after 10,000 yr B.P. The present stable ice cover is achieved at 6500 yr B.P. Ice growth and decay are characterized by thresholds which separate periods of steady state from periods of rapid transition; the thresholds usually relate to topography. Tests show that ice sheet behavior is most sensitive to sea-level change, basal marine melting, and accumulation and is less sensitive to isostasy, spatial variation in accumulation, calving rates, and ice flow parameterization. Tests of the model against field evidence show good agreement in places, as well as discrepancies which require further work.

Various spatial discretizations for the ice sheet are compared for accuracy against analytical solutions in one and two dimensions. The computational efficiency of various iterated and non-iterated marching schemes is compared.

The stability properties of different marching schemes, with and without iterations on the non-linear equations, are compared. Newton–Raphson techniques permit the largest time steps. A new technique, which is based on the fact that the dynamics of unstable iterated maps contain information about where the unstable root lies, is shown to improve substantially the performance of Picard iteration at a negligible computational cost.

Holocene climatic variability and human impact on vegetation are reconstructed from a region in central European Russia, which lies at an important ecotone between broadleaf forest and steppe. For the first time in this region we adopt a multi-proxy approach that combines analysis of local mire conditions from plant macrofossil and testate amoeba analyses with pollen-based quantitative climate reconstruction. The proxies indicate a long-term warming trend from 9700 to 7500 cal yr BP, interrupted by a series of short-term cold events. From 7500 to 5000 cal yr BP the results imply a relatively stable climate, warmer and drier than present, spanning the Holocene Thermal Maximum. Since 5000 cal yr BP the data suggest a change to cooler climate, but with centennial-scale variability. This shift at around 5000 cal yr BP is supported by extensive evidence from other sites. In the early Holocene, the region was occupied mainly by pine and birch forests. Broad-leafed forests of oak, lime and elm expanded after 7800 cal yr BP and remained dominant until the last few centuries. During the historical period, vegetation changes have been driven mainly by human activities.

USDA uses the concept of “publish-ability” rather than statistical reliability of an estimate for quality validation of USDA estimates, which is solely based on the sample size and the coefficient of variation (CV). We demonstrate conceptually how the reliability of the sample mean can be tested by estimating the upper and lower bounds of the confidence interval for an unknown population mean using the CV. However, the reliability test for the sample mean can be made only under the normality assumption. USDA multiple-way Agricultural Resource Management Survey (ARMS) estimates are used to illustrate the relative measure of precision for sample-based estimators.

We report the results of a sensitive survey of planetary nebulae in all four ground state OH lines. Our results confirm that evolved planetary nebulae are not OH sources in general. However, we did detect one interesting object: an OH 1612 MHz maser in the young planetary nebula NGC 6302. This nebula may be in a brief evolutionary stage, similar to the young and compact planetary nebula Vy 2-2 where OH has already been detected.

The infrared S(1) line of molecular hydrogen has been searched for in twenty-two planetary nebulae using the imaging mode of the Anglo-Australian Telescope. The line was detected and mapped in eleven objects. It has been demonstrated that all those with strong excited molecular hydrogen belong to a subclass of the Type I planetary nebulae, morphologically consisting of an equatorial toroid with faint bipolar extensions. Furthermore, nearly all planetaries with these characteristics have strong molecular hydrogen. The molecular line ratios in the 2.0 to 2.5 micron window are consistent with shock excitation. The observations suggest that the morphology of these planetaries has been controlled by a fast stellar wind interacting with a disc of gas concentrated in the equatorial plane.

In this paper it is shown that the ability to directly detect a daughter atom, using resonance ionization spectroscopy, in delayed time coincidence with the decay of a parent species promises to drastically reduce the background in low-level counting experiments. In addition, resonance ionization can also be used as an ion source for a mass spectrometer system that is capable of discriminating between isobars.

A forecast of future development for a period of 10 years postulates a complete change in civil air transport. Future city centre heliport developments are considered from an airport operator's point of view.

Full consideration has been given to helicopter sites in London by the Morris Report of 1961 and a VTOL Working Party of the Aeronautical Research Committee is now considering a report on the siting of Terminals for an Intraurban VTOL transport system.

Generally, the main considerations of committees on heliports consider the problems under the headings: —

1. Characteristics of the aircraft.

2. Noise limitations.

3. Safety, including aerodynamic effect of neighbouring buildings.

4. Air traffic control and operating procedures.

5. Traffic growth considerations.

6. Design layout and location of terminals.

7. Access to the city centre must be good and possibly not more than 15 minutes journey time.

The Cooper-Harper scale is currently the only well-established scale for assessing aircraft handling qualities. However, as a result of having a unidimensional format the Cooper-Harper scale lacks diagnostic power and has also been criticised for exhibiting poor reliability. The Cranfield Aircraft Handling Qualities, Rating Scale (CAHQRS) is a new, multidimensional rating scale using concepts from two established scales, the NASA-TLX workload scale and the Cooper-Harper scale. This paper provides an overview of the development of the CAHQRS and the results from a series of validation trials in an engineering flight simulator. An in-flight refuelling task and an approach and landing task using a range of control laws were used in these evaluations. The results showed that the CAHQRS had high positive correlations with the Cooper-Harper scale. However, the CAHQRS also demonstrated greater validity, diagnostic power and higher test/re-test reliability than the previous scale.

Passenger traffic through the seven BAA airports, Heathrow, Gatwick and Stansted in the South-East and Glasgow, Edinburgh, Prestwick and Aberdeen in Scotland is predominantly in the leisure sector and this sector is most affected by low fares. In 1978 this sector formed 65% of all traffic at the three South-East airports and 55% at the four airports in Scotland.

As Ray Colegate and Adam Thomson have said low fares are no new choice for air travellers. Low fares for charter operations with a range of fare options have been the main feature of the rapid passenger growth at Gatwick Airport for many years. This is also the case at Luton Airport which is not owned by the BAA but serves the South-East.

Mongolia's Gobi Desert ecosystem, a stronghold for populations of the Asiatic wild ass (khulan) Equus hemionus and the goitered gazelle Gazella subgutturosa, faces conservation challenges as a result of rapid economic development, including mining-related infrastructure projects. There is a paucity of reliable data on population abundance for these ungulates in the region, which makes it difficult to assess how they are responding to increasing anthropogenic pressure. Our aim was to obtain abundance estimates for khulan and goitered gazelles to inform their management and form the basis of a long-term monitoring programme. Each year during 2012–2015 we surveyed a total of 64 line transects spaced 20 km apart, with a total of 3,464 km of survey effort across 78,717 km2. Distance sampling analysis provided annual estimates of density and abundance, which were cross-referenced with the results of an aerial survey conducted in 2013. Overall, we observed 784 groups (14,608 individuals) of khulan and 1,033 groups (3,955 individuals) of goitered gazelles during the four surveys. The abundance estimates for 2013 were 35,899 (95% CI 22,680–40,537) khulan and 28,462 (95% CI 21,326–37,987) goitered gazelles. These estimates were congruent with the results from the aerial survey, which overlapped spatially and temporally with our ground-based survey. Our findings confirm that Mongolia's Gobi Desert supports the largest population of khulan and goitered gazelles in the world, and we provide a critical update on the status of the two species.

At least in conventional hydrostatic ice-sheet models, the numerical error associated with grounding line dynamics can be reduced by modifications to the discretization scheme. These involve altering the integration formulae for the basal traction and/or driving stress close to the grounding line and exhibit lower – if still first-order – error in the MISMIP3d experiments. MISMIP3d may not represent the variety of real ice streams, in that it lacks strong lateral stresses, and imposes a large basal traction at the grounding line. We study resolution sensitivity in the context of extreme forcing simulations of the entire Antarctic ice sheet, using the BISICLES adaptive mesh ice-sheet model with two schemes: the original treatment, and a scheme, which modifies the discretization of the basal traction. The second scheme does indeed improve accuracy – by around a factor of two – for a given mesh spacing, but $\lesssim 1$ km resolution is still necessary. For example, in coarser resolution simulations Thwaites Glacier retreats so slowly that other ice streams divert its trunk. In contrast, with $\lesssim 1$ km meshes, the same glacier retreats far more quickly and triggers the final phase of West Antarctic collapse a century before any such diversion can take place.

Present-day mass loss from the West Antarctic ice sheet is centred on the Amundsen Sea Embayment (ASE), primarily through ice streams, including Pine Island, Thwaites and Smith glaciers. To understand the differences in response of these ice streams, we ran a perturbed parameter ensemble, using a vertically-integrated ice flow model with adaptive mesh refinement. We generated 71 sets of three physical parameters (basal traction coefficient, ice viscosity stiffening factor and sub-shelf melt rate), which we used to simulate the ASE for 50 years. We also explored the effects of different bed geometries and basal sliding laws. The mean rate of sea-level rise across the ensemble of simulations is comparable with current observed rates for the ASE. We found evidence that grounding line dynamics are sensitive to features in the bed geometry: simulations using BedMap2 geometry resulted in a higher rate of sea-level rise than simulations using a rougher geometry, created using mass conservation. Modelled grounding-line retreat of all the three ice streams was sensitive to viscosity and basal traction, while the melt rate was more important in Pine Island and Smith glaciers, which flow through more confined ice shelves than Thwaites, which has a relatively unconfined shelf.

The following lines give a summary of the work concerning Kapteyn’s Plan of Selected Areas up to December 1937.