2,580 research outputs found
The effect of SU-8 patterned surfaces on the response of the quartz crystal microbalance
In this work we present data showing the effect of patterning layers of SU-8 photoresist on a quartz crystal microbalance (QCM) and subsequent chemical treatment to increase their hydrophobicity. Patterns with 5 mu m diameter pillars spaced every 10 mu m have been fabricated with heights of 3, 5 and 10 mu m in addition to equivalent thickness flat layers. Contact angle measurements have been made before and after the hydrophobic chemical treatment. The change in resonant frequency of the QCM has been investigated as the surfaces were submerged in solutions of water/PEG with changing viscosity-density product
The Dimensional-Reduction Anomaly in Spherically Symmetric Spacetimes
In D-dimensional spacetimes which can be foliated by n-dimensional
homogeneous subspaces, a quantum field can be decomposed in terms of modes on
the subspaces, reducing the system to a collection of (D-n)-dimensional fields.
This allows one to write bare D-dimensional field quantities like the Green
function and the effective action as sums of their (D-n)-dimensional
counterparts in the dimensionally reduced theory. It has been shown, however,
that renormalization breaks this relationship between the original and
dimensionally reduced theories, an effect called the dimensional-reduction
anomaly. We examine the dimensional-reduction anomaly for the important case of
spherically symmetric spaces.Comment: LaTeX, 19 pages, 2 figures. v2: calculations simplified, references
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How the composition of sandstone matrices affects rates of soil formation
Soils deliver multiple ecosystem services and their long-term sustainability is fundamentally controlled by the rates at which they form and erode. Our knowledge and understanding of soil formation is not commensurate with that of soil erosion, in part due to the difficulty of measuring the former. However, developments in cosmogenic radionuclide accumulation models have enabled soil scientists to more accurately constrain the rates at which soils form from bedrock. To date, all three major rock types â igneous, sedimentary and metamorphic lithologies â have been examined in such work. Soil formation rates have been measured and compared between these rock types, but the impact of rock characteristics on soil formation rates, such as rock matrices and mineralogy, have seldom been explored. In this UK-based study, we used cosmogenic radionuclide analysis to investigate whether the lithological variability of sandstone governs pedogenesis. Soil formation rates were measured on two arable hillslopes at Woburn and Hilton, which are underlain by different types of arenite sandstone. Rates were faster at Woburn, and we suggest that this is due to the fact that the Woburn sandstone formation is less cemented that that at Hilton. Similarly, rates at Woburn and Hilton were found to be faster than those measured at two other sandstone-based sites in the UK, and faster than those compiled in a global inventory of cosmogenic studies on sandstone-based soils. We suggest that the cementing agents present in matrix-abundant wackes studied previously may afford these sandstones greater structural integrity and resistance to weathering. This work points to the importance of factoring bedrock matrices into our understanding of soil formation rates, and the biogeochemical cycles these underpi
Fluvial organic carbon flux from an eroding peatland catchment, southern Pennines, UK
This study investigates for the first time the relative importance of dissolved organic carbon (DOC) and particulate organic carbon (POC) in the fluvial carbon flux from an actively eroding peatland catchment in the southern Pennines, UK. Event scale variability in DOC and POC was examined and the annual flux of fluvial organic carbon was estimated for the catchment. At the event scale, both DOC and POC were found to increase with discharge, with event based POC export accounting for 95% of flux in only 8% of the time. On an annual cycle, exports of 35.14 t organic carbon (OC) are estimated from the catchment, which represents an areal value of 92.47 g C m<sup>&minus;2</sup> a<sup>&minus;1</sup>. POC was the most significant form of organic carbon export, accounting for 80% of the estimated flux. This suggests that more research is required on both the fate of POC and the rates of POC export in eroding peatland catchments
Homogenization of weakly coupled systems of Hamilton--Jacobi equations with fast switching rates
We consider homogenization for weakly coupled systems of Hamilton--Jacobi
equations with fast switching rates. The fast switching rate terms force the
solutions converge to the same limit, which is a solution of the effective
equation. We discover the appearance of the initial layers, which appear
naturally when we consider the systems with different initial data and analyze
them rigorously. In particular, we obtain matched asymptotic solutions of the
systems and rate of convergence. We also investigate properties of the
effective Hamiltonian of weakly coupled systems and show some examples which do
not appear in the context of single equations.Comment: final version, to appear in Arch. Ration. Mech. Ana
Revised spherically symmetric solutions of gravity
We study spherically symmetric static empty space solutions in
model of gravity. We show that the Schwarzschild
metric is an exact solution of the resulted field equations and consequently
there are general solutions which {are perturbed Schwarzschild metric and
viable for solar system. Our results for large scale contains a logarithmic
term with a coefficient producing a repulsive gravity force which is in
agreement with the positive acceleration of the universe.Comment: 8 page
Comment on: âPeatland carbon stocks and burn history: Blanket bog peat core evidence highlights charcoal impacts on peat physical properties and long-term carbon storageâ, by A. Heinemeyer, Q. Asena, W.L. Burn and A.L. Jones (Geo: Geography and Environment. 2018; e00063)
A recent paper by Heinemeyer et al. (2018) in this journal has suggested that the use of prescribed fire may enhance carbon accumulation in UK upland blanket bogs. We challenge this finding based on a number of concerns with the original manuscript including the lack of an unburned control, insufficient replication, unrecognised potential confounding factors, and potentially large inaccuracies in the core dating approach used to calculate carbon accumulation rates. We argue that burnâmanagement of peatlands is more likely to lead to carbon loss than carbon gain
Of cattle and feasts: multi-isotope investigation of animal husbandry and communal feasting at Neolithic Makriyalos, northern Greece
The aim of this study is to investigate livestock husbandry and its relationship to the mobilization
of domestic animals for slaughter at large communal feasting events, in Late Neolithic
Makriyalos, northern Greece. A multi-isotope approach is built that integrates analysis of:
1. δ13C and δ15N values of human and animal bone collagen for understanding long-term dietary
behavior,
2. Incremental δ13C and δ18O values of domestic animal tooth enamel carbonate for assessing
seasonal patterns in grazing habits and mobility, and
3. 87Sr/86Sr ratios of cattle tooth enamel for examining the possibility that some of the animals
consumed at the site were born outside the local environment.
The findings indicate that cattle had isotopically more variable diets than sheep, which
may reflect grazing over a wider catchment area in the local landscape. Cattle products did
not make a significant contribution to the long-term dietary protein intake of the humans,
which may indicate that they were primarily consumed during episodic feasting events.
There is no indication that pasturing of livestock was pre-determined by their eventual context
of slaughter (i.e. large-scale feasting vs. more routine consumption events). Two nonlocal
cattle identified among those deposited in a feasting context may have been brought to
the site as contributions to these feasts. The evidence presented provides a more detailed
insight into local land use and into the role of livestock and feasting in forging social relationships
within the regional human population
Problems and possibilities in fine-tuning of the Cepheid P-L relationship
Factors contributing to the scatter around the ridge-line period-luminosity
relationship are listed, followed by a discussion how to eliminate the adverse
effects of these factors (mode of pulsation, crossing number, temperature
range, reddening, binarity, metallicity, non-linearity of the relationship,
blending), in order to reduce the dispersion of the P-L relationship.Comment: 7 pages, 8 figures; accepted for publication in Astrophysics & Space
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