1,201 research outputs found
Britain, America and the origins of the European Payments Union: a reassessment
Working paper authored jointly by Till Geiger (University of Manchester) and Richard Toye (University of Exeter).This working papers offers a revisionist approach to the founding of the European Payments Union (EPU) in 1950.Leverhulme Trus
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High post-anthesis temperature effects on 3 bread wheat (Triticum aestivum L.) grain 4 transcriptome during early grain-filling
Background: High post-anthesis (p.a) temperatures reduce mature grain weights in wheat and other cereals.
However, the causes of this reduction are not entirely known. Control of grain expansion by the maternally derived pericarp of the grain has previously been suggested, although this interaction has not been investigated under high p.a. temperatures. Down-regulation of pericarp localised genes that regulate cell wall expansion under high p.a. temperatures may limit expansion of the encapsulated endosperm due to a loss of plasticity in the pericarp,reducing mature grain weight. Here the effect of high p.a. temperatures on the transcriptome of the pericarp and endosperm of the wheat grain during early grain-filling was investigated via RNA-Seq and is discussed alongside grain moisture dynamics during early grain development and mature grain weight.
Results: High p.a. temperatures applied from 6-days after anthesis (daa) and until 18daa reduced the grain’s ability to accumulate water, with total grain moisture and percentage grain moisture content being significantly reduced from 14daa onwards. Mature grain weight was also significantly reduced by the same high p.a. temperatures
applied from 6daa for 4-days or more, in a separate experiment. Comparison of our RNA-Seq data from whole
grains, with existing data sets from isolated pericarp and endosperm tissues enabled the identification of subsets of genes whose expression was significantly affected by high p.a. temperature and predominantly expressed in either tissue. Hierarchical clustering and gene ontology analysis resulted in the identification of a number of genes implicated in the regulation of cell wall expansion, predominantly expressed in the pericarp and significantly down26 regulated under high p.a. temperatures, including endoglucanase, xyloglucan endotransglycosylases and a β27 expansin. An over-representation of genes involved in the ‘cuticle development’ functional pathway that were
expressed in the pericarp and affected by high p.a. temperatures was also observed.
Conclusions: High p.a. temperature induced down-regulation of genes involved in regulating pericarp cell wall expansion. This concomitant down-regulation with a reduction in total grain moisture content and grain weight following the same treatment period, adds support to the theory that high p.a. temperatures may cause a
reduction in mature grain weight as result of decreased pericarp cell wall expansion
Efficient topology optimization using compatibility projection in micromechanical homogenization
The adjoint method allows efficient calculation of the gradient with respect
to the design variables of a topology optimization problem. This method is
almost exclusively used in combination with traditional
Finite-Element-Analysis, whereas Fourier-based solvers have recently shown
large efficiency gains for homogenization problems. In this paper, we derive
the discrete adjoint method for Fourier-based solvers that employ compatibility
projection. We demonstrate the method on the optimization of composite
materials and auxetic metamaterials, where void regions are modelled with zero
stiffness.Comment: 17 pages, 5 figure
Mathematical modeling of char reactivity in Ar-O2 and CO2-O2 mixtures
The kinetics of the coal char + O2 reaction was studied by thermogravimetry. Low sample masses were employed to ensure an approximate kinetic regime. Special emphasis was placed on clarifying how the recirculation of the flue gases (i.e. the presence of a high amount of CO2 at low O2 concentrations) affects the reactivity. The ambient gas concentrations varied from 100% O2 to 5% O2 in CO2 or Ar. A semi-empirical model is presented which can approximate the reactivity changes during the conversion and takes into account the heterogeneity of the samples. A least squares evaluation procedure resulted in a good fit to the experimental data over a wide variety of temperature programs and ambient gas concentrations. The overall burn-off time of the samples varied from eight minutes to three hours depending on the experimental conditions. The reaction rate was found to be proportional to the O2 concentration of the ambient gas and was not influenced by the presence of high amounts of CO2. The reaction started with a sharp acceleration period indicating an initial activation of the char surface
Railways, Growth, and Industrialisation in a Developing German Economy, 1829-1910
This paper provides a comprehensive assessment of the effect of railways on the spatial economic development of a German economy, the Kingdom of Württemberg, during the Industrial Revolution. Our identification strategy compares the economic development of `winning' municipalities that were connected to the railway in 1845-54 to the development of `losing' municipalities that were the runners-up choice for a given railway line between two major towns. Estimates from both differences-in-differences and inverse-probability-weighted models suggest that railway access increased annual population growth by 0.4 percentage points over more than half a century. Railways also increased wages, income and housing values, in line with predictions of economic geography models of transport infrastructure improvements, reduced the gender wage gap, and accelerated the transition away from agriculture. We find little evidence that these effects are driven by localised displacement effects
The emergence of small-scale self-affine surface roughness from deformation
Most natural and man-made surfaces appear to be rough on many length scales. There is presently no unifying theory of the origin of roughness or the self-affine nature of surface topography. One likely contributor to the formation of roughness is deformation, which underlies many processes that shape surfaces such as machining, fracture, and wear. Using molecular dynamics, we simulate the biaxial compression of single-crystal Au, the high-entropy alloy Ni36.67Co30Fe16.67Ti16.67, and amorphous Cu50Zr50 and show that even surfaces of homogeneous materials develop a self-affine structure. By characterizing subsurface deformation, we connect the self-affinity of the surface to the spatial correlation of deformation events occurring within the bulk and present scaling relations for the evolution of roughness with strain. These results open routes toward interpreting and engineering roughness profiles
Railways, Growth, and Industrialisation in a Developing German Economy, 1829-1910
This paper provides a comprehensive assessment of the effect of railways on the spatial economic development of a German economy, the Kingdom of Württemberg, during the Industrial Revolution. Our identification strategy compares the economic development of `winning' municipalities that were connected to the railway in 1845-54 to the development of `losing' municipalities that were the runners-up choice for a given railway line between two major towns. Estimates from both differences-in-differences and inverse-probability-weighted models suggest that railway access increased annual population growth by 0.4 percentage points over more than half a century. Railways also increased wages, income and housing values, in line with predictions of economic geography models of transport infrastructure improvements, reduced the gender wage gap, and accelerated the transition away from agriculture. We find little evidence that these effects are driven by localised displacement effects
All-optical manipulation of singlet exciton transport in individual supramolecular nanostructures by triplet gating
Directed transport of singlet excitation energy is a key process in natural light-harvesting systems and a desired feature in assemblies of functional organic molecules for organic electronics and nanotechnology applications. However, progress in this direction is hampered by the lack of concepts and model systems. Here we demonstrate an all-optical approach to manipulate singlet exciton transport pathways within supramolecular nanostructures via singlet-triplet annihilation, i.e., to enforce an effective motion of singlet excitons along a predefined direction. For this proof-of-concept, we locally photo-generate a long-lived triplet exciton population and subsequently a singlet exciton population on single bundles of H-type supramolecular nanofibres using two temporally and spatially separated laser pulses. The local triplet exciton population operates as a gate for the singlet exciton transport since singlet-triplet annihilation hinders singlet exciton motion across the triplet population. We visualize this manipulation of singlet exciton transport via the fluorescence signal from the singlet excitons, using a detection-beam scanning approach combined with time-correlated single-photon counting. Our reversible, all-optical manipulation of singlet exciton transport can pave the way to realising new design principles for functional photonic nanodevices
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