2,799 research outputs found
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Investigation of peatland restoration (grip blocking) techniques to achieve best outcomes for methane and greenhouse gas emissions/balance. Controlled Environment (Mesocosm) Experiment. Final Report to Defra. Project code SP1202
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Plastic Microbial Acclimation and Optimisation of Composting and Anaerobic Digestion Processes may Improve Degradation Times
Understanding the influence of farmer motivations on changes to soil erosion risk on sites of former serious erosion in the South Downs National Park, UK
Serious soil erosion occurred in the South Downs National Park, southern England in the years 1982–2006 and details of around 400 sites are contained in a database. In 2010 we revisited 85 of the most serious sites where erosion of >10 m3 ha−1 y−1 had been recorded in order to assess land use change and any conservation measures undertaken. At 79% of the sites land use change had resulted in a reduction in the risk of erosion, most notably at 28 sites with a shift to permanent grass from winter cereals. At only 21% of sites was the risk of erosion unchanged. Twenty two farmers responsible for 66 of the sites were interviewed. Land management practices had changed on all of the fields of interest to this study since the time of the serious erosion events, to those which have the potential to lower soil erosion risk. Sixteen interviewees claimed that erosion was a motivating reason for changing their practices, due to either experiencing on or on- and off-farm impacts firsthand (12), having knowledge or suspicion of serious erosion having occurred on their land prior to their management (three), or having no knowledge of any serious erosion on their land but just wanting to reduce overall erosion risk (one). Amongst the main changes reported are changes of land use from winter cereals to grass or to overwinter stubble which have undoubtedly reduced the risk of erosion. However, some changed practices claimed by farmers, such as along-the-contour-working, earlier sowing and the use of rollers may be of little value. Furthermore, deeper analysis of farmers’ motivations regarding changes in land management practices suggests a complex picture in which a range of socio-economic influences come into play over time including financial incentives offered by agri-environmental schemes which were found to be an important driver of change. Future changes in farming economics may therefore undermine the reduction in erosion risk in the longer term
The closed spiracle phase of discontinuous gas exchange predicts diving duration in the grasshopper Paracinema tricolor
The discontinuous gas exchange (DGE) pattern of respiration shown
by many arthropods includes periods of spiracle closure (C-phase)
and is largely thought to serve as a physiological adaptation to restrict
water loss in terrestrial environments. One major challenge to this
hypothesis is to explain the presence of DGE in insects in moist
environments. Here, we show a novel ecological correlate of the
C-phase, namely, diving behaviour in mesic Paracinema tricolor
grasshoppers. Notably, maximal dive duration is positively correlated
with C-phase length, even after accounting for mass scaling and
absolute metabolic rate. Here, we propose that an additional
advantage of DGE may be conferred by allowing the tracheal
system to act as a sealed underwater oxygen reservoir. Spiracle
closure may facilitate underwater submersion, which, in turn, may
contribute to predator avoidance, the survival of accidental immersion
or periodic flooding and the exploitation of underwater resources
Gyrotropic impact upon negatively refracting surfaces
Surface wave propagation at the interface between different types of gyrotropic materials and an isotropic negatively refracting medium, in which the relative permittivity and relative permeability are, simultaneously, negative is investigated. A general approach is taken that embraces both gyroelectric and gyromagnetic materials, permitting the possibility of operating in either the low GHz, THz or the optical frequency regimes. The classical transverse Voigt configuration is adopted and a complete analysis of non-reciprocal surface wave dispersion is presented. The impact of the surface polariton modes upon the reflection of both plane waves and beams is discussed in terms of resonances and an example of the influence upon the Goos–Hänchen shift is given
Nonlinear surface waves in left-handed materials
We study both linear and nonlinear surface waves localized at the interface
separating a left-handed medium (i.e. the medium with both negative dielectric
permittivity and negative magnetic permeability) and a conventional (or
right-handed) dielectric medium. We demonstrate that the interface can support
both TE- and TM-polarized surface waves - surface polaritons, and we study
their properties. We describe the intensity-dependent properties of nonlinear
surface waves in three different cases, i.e. when both the LH and RH media are
nonlinear and when either of the media is nonlinear. In the case when both
media are nonlinear, we find two types of nonlinear surface waves, one with the
maximum amplitude at the interface, and the other one with two humps. In the
case when one medium is nonlinear, only one type of surface wave exists, which
has the maximum electric field at the interface, unlike waves in right-handed
materials where the surface-wave maximum is usually shifted into a
self-focussing nonlinear medium. We discus the possibility of tuning the wave
group velocity in both the linear and nonlinear cases, and show that
group-velocity dispersion, which leads to pulse broadening, can be balanced by
the nonlinearity of the media, so resulting in soliton propagation.Comment: 9 pages, 10 figure
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Greenhouse gas emissions from non-recyclable residual household waste within domestic wheeled bins
The evolution of greenhouse gases (GHGs) from waste treatment processes (e.g. landfill & composting) are well documented (Chen and Lin, 2008), frequently quantified (Lou and Nair, 2009) and currently represented within climate change models (Ciais et al., 2013). Conversely, the understanding of GHG emissions from household waste (pre-collection) is largely unknown and confined to composting studies (e.g. Andersen et al., 2010), or calculating the calorific value/elemental content (Komilis et al., 2012) and biological methane potential (Alibardi and Cossu, 2015) of municipal solid waste. Generating a better understanding of GHG fluxes from non-recycled residual household waste before collection may help to further refine climate models and inform policy makers regarding the best collection strategy to mitigate GHG emissions
Public sector reforms, privatisation and regimes of control in a Chinese enterprise
The Chinese economic reform has recently become a major focus of attention around the world. The underlying rationale for the Chinese government's privatisation and public sector reforms is the view that reformed state enterprises and privately managed firms will demonstrate superior management control and better performance, and hence encourage economic growth and employment. There are very few intensive case studies published in English journals studying whether firms privatised in China have reversed previous losses and introduced better management controls, leading to increased investment, productivity, and overall organizational effectiveness and efficiency. The researchers do not seek to deny the control problems of Chinese SOEs, but question the consequences of the new controls installed during the post-privatisation period. The paper also reveals a declining tendency in employment; altered distributions of wealth ? especially to the state ? and labour, and a lack of improvements in the accountability of privatised companies. Overall, the paper argues, the aims of reform policies in China, including better control, increased profitability and an improved working life for Chinese people, have not materialized. The paper calls for more research on the above issues in the Chinese context
Calculating Nonlocal Optical Properties of Structures with Arbitrary Shape
In a recent Letter [Phys. Rev. Lett. 103, 097403 (2009)], we outlined a
computational method to calculate the optical properties of structures with a
spatially nonlocal dielectric function. In this Article, we detail the full
method, and verify it against analytical results for cylindrical nanowires.
Then, as examples of our method, we calculate the optical properties of Au
nanostructures in one, two, and three dimensions. We first calculate the
transmission, reflection, and absorption spectra of thin films. Because of
their simplicity, these systems demonstrate clearly the longitudinal (or
volume) plasmons characteristic of nonlocal effects, which result in anomalous
absorption and plasmon blueshifting. We then study the optical properties of
spherical nanoparticles, which also exhibit such nonlocal effects. Finally, we
compare the maximum and average electric field enhancements around nanowires of
various shapes to local theory predictions. We demonstrate that when nonlocal
effects are included, significant decreases in such properties can occur.Comment: 30 pages, 12 figures, 1 tabl
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