1,691 research outputs found
Review of Landmarks, by Robert Macfarlane. Published by Hamish Hamilton, London, 2015. Cover price £20.00.
A review of Robert Macfarlane\u27s book, Landmarks
Review: John Lewis-Stempel, The Wood: the Life and Times of Cockshutt Wood
This review comments on a recent book by an award-winning author that elegantly combines the notions of landscape, language an sustainability in a year\u27s diary describing the changes in a small area of woodland in Herefordshire, in the borderland between England and Wales
Developing an Aggregate Marginal Cost per Flying Hour Model for the U.S. Air Force\u27s F-15 Fighter Aircraft
This thesis applies econometric techniques to build a marginal cost per flying hour model for the U.S. Air Force\u27s F-15CD and E fleets. It used monthly economic, programmatic, operational, and climatology data from FY01-FY04 to construct Depot Level Reparable (DLR) and Consumable (CONS) models on the aggregate level. It incorporated the use of panel data analysis to explore the effect each of the independent variables had on the CPFH rate by time and by base. This allowed it to capture not only the temporal (time) interactions, but also the spatial (cross-sectional) interactions, providing a more robust analysis of the dynamics between the independent variables, bases, time and the CPFH rates. It discovered the DLR and CONS CPFH rates have a significant business cycle/seasonal trend component. Also, the following variables were found to be statistically and economically significant: average sortie duration, mean monthly temperature difference, and the Zero Base Transfer CPFH program change. These models when compared to the currently available models significantly out-performed these models. On average, the relative error rate for this research\u27s models was half that of the current models. Therefore, an aggregate CPFH model can be developed to accurately forecast the CPFH rates
A comparative study of the ecology of smooth flounder, Pleuronectes putnami, and winter flounder, Pleuronectes americanus, from Great Bay Estuary, New Hampshire
Smooth flounder, Pleuronectes putnami, and winter flounder, Pleuronectes americanus, co-occur in estuaries along the east coast of North America from Labrador to Massachusetts. Results of a three year sampling program indicated that the two species were partially segregated along salinity and depth gradients in upper Great Bay Estuary, New Hampshire. Along the salinity gradient, smooth flounder were most abundant at the oligo-mesohaline riverine habitat while winter flounder were most abundant at the meso-polyhaline open bay habitat. Both species exhibited a generalized up-river movement with seasonally increasing salinity. Smooth flounder showed ontogenetic changes in distribution along the depth gradient, with the smallest individuals occupying the shallowest depths. Intertidal mudflats were an important nursery area for young-of-year smooth flounder but not for young-of-year winter flounder.
Laboratory and field experiments demonstrated that the distribution of smooth and winter flounder in Great Bay Estuary was based primarily, although not completely, on physiological constraints related to salinity. For smooth flounder, growth and survival were best in 12\perthous and 22\perthous, while for winter flounder, growth and survival were best at 22\perthous and 32\perthous. Both flounder species occupied sites along the salinity gradient that were metabolically least costly.
Seasonal changes in resource use were examined at several estuarine sites. Smooth and winter flounder had similar diets and showed greater overlap in diet than in habitat use. Important prey types included the polychaetes Streblospio benedicti and Scolecolepides viridis, siphons of the bivalve Macoma balthica, and gammarid amphipods. Prey abundance changed seasonally and appeared to play a role in affecting the distribution of smooth and winter flounder. Differences in diet among estuarine sites reflected differences in the benthic fauna at these sites. Even though their diets were similar, there were no consistent patterns in niche metrics to suggest that food was limiting to smooth and winter flounder in upper Great Bay Estuary
Darwin’s Landscapes (and Seascapes)
Charles Darwin, particularly in his early writings, had a strong appreciation of landscape. He describes scenery that he regarded as attractive and spectacular in his writings from the Beagle period with considerable perception. Through much of his career, he integrated ideas and facts from different sources supremely well; thus understanding that a landscape was a product of the rocks, the processes they had undergone, vegetation, animal life, and human activities. Another component in the development of his appreciation of landscape – or ‘scenery’ as he usually identified it – was his quite strong aesthetic sense which existed from his teenage years through the Beagle voyage. Later, he felt it atrophied. He also, of course, emphasised the notion of gradualism – the idea that entities such as plants, animals, rocks and landforms underwent gradual change over long periods of time. This notion, which he drew from Charles Lyell’s geology, was important in the subsequent development of evolutionary biology and many other branches of science, including landscape analysis
Monte Carlo studies of the GCT for the Cherenkov Telescope Array and the search for VHE AGN using cluster analysis
The future ground based gamma-ray observatory, the Cherenkov Telescope Array (CTA), will soon enter its construction phase. This work therefore looks into providing a better model of one of the small size telescopes, the Gamma Cherenkov Telescope (GCT), for input into Monte Carlo simulations. Evaluation of these models shows that both a telescope equipped with MaPM (GCTM) and SiPM (GCTS) detector modules should meet if not exceed certain CTA requirements. To determine possible early science deliverables, a study into the performance of a small 7 telescope array, along with an extrapolation up to the full complement of SSTs is presented. This reveals promising results for both configurations, with GCTS
performing better than GCTM. This work also presents an investigation into the use of local muons as a form of absolute calibration of the GCT telescope. It has
been shown that, while there are some difficulties, the method should be possible. The remainder of this thesis presents results obtained from applying the clustering
algorithm DBSCAN to the Fermi-LAT data in the very high energy (VHE) regime. This includes 9 sources detected in the Pass 7 reprocessed data set and 70 in the improved Pass 8 data set. These sources represent promising candidates for follow-up observations with current ground-based gamma-ray observatories and helps to frame the science goals of CTA
Cooled propylene glycol as a pragmatic choice for preservation of DNA from remote field-collected Diptera for next-generation sequence analysis
Next-generation sequencing (NGS)-based methods can now be applied to large population-scale studies, but this demands very high-quality DNA. For specimens collected from remote field locations, DNA degradation can be a problem, requiring logistically challenging preservation techniques. Simpler preservation techniques are therefore required. Prior to collection of exotic fruit fly (Tephritidae) species, a number of readily available preservatives with storage at either 4°C or room temperature were trialed here to determine the DNA quality for three locally available Diptera species,Fannia canicularis(L.),Musca domesticaL., and Lucilia sericataMeigen. Considerable variation was observed between the different preservatives, species, and temperatures, but several preservatives at 4°C were favored. Chilled propylene glycol was subsequently used for the storage and carriage of Australian field-collectedBactrocera fruit fly specimens to New Zealand. When processed up to 20 d later, DNA fragments of ∼10-20 kb were obtained for successful genotyping by sequencing analysis. This protocol is therefore recommended as a logistically simple and safe approach for distant collection of dipteran samples for NGS population genomic studies
Binning is Sinning: Redemption for Hubble Diagram using Photometrically Classified Type Ia Supernovae
Bayesian Estimation Applied to Multiple Species (BEAMS) has been implemented
in the BEAMS with Bias Corrections (BBC) framework to produce a redshift-binned
Hubble diagram (HD) for Type Ia Supernovae (SN Ia). The BBC method corrects for
selection effects and non-SNIa contamination, and systematic uncertainties are
described by a covariance matrix with dimension matching the number of BBC
redshift bins. For spectroscopically confirmed SNIa samples, a recent "Binning
is Sinning" article (BHS21, arxiv:2012.05900) showed that an unbinned HD and
covariance matrix reduces the systematic uncertainty by a factor of 1.5
compared to the binned approach. Here we extend their analysis to obtain an
unbinned HD for a photometrically identified sample processed with BBC. To test
this new method, we simulate and analyze 50 samples corresponding to the Dark
Energy Survey (DES) with a low-redshift anchor; the simulation includes SNe Ia,
and contaminants from core collapse SNe and peculiar SNe Ia. The analysis
includes systematic uncertainties for calibration, and measures the dark energy
equation of state parameter (w). Compared to a redshift-binned HD, the unbinned
HD with nearly 2,000 events results in a smaller systematic uncertainty, in
qualitative agreement with BHS21, and averaging results among the 50 samples we
find no evidence for bias in measured cosmological parameters. To reduce
computation time for fitting an unbinned HD with large samples, we propose an
HD-rebinning method that defines the HD in bins of redshift, color, and
stretch; the rebinned HD results in similar uncertainty as the unbinned case,
and shows no evidence for biased cosmology parameters
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