7,752 research outputs found
English economic growth, 1270-1700
We provide annual estimates of GDP for England over the period 1270-1700,
constructed from the output side. The GDP data are combined with population estimates
to calculate GDP per capita. Sectoral price data and estimates of nominal GDP are also
provided. We find per capita income growth of 0.20 per cent per annum, although growth
was episodic, with the strongest growth after the Black Death and in the second half of
the seventeenth century. Living standards in the late medieval period were well above
âbare bones subsistenceâ, although levels of kilocalorie consumption per head were
modest because of the very large share of pastoral production in agriculture
British economic growth : 1270 - 1870
We provide annual estimates of GDP for England between 1270 and 1700 and
for Great Britain between 1700 and 1870, constructed from the output side. The GDP
data are combined with population estimates to calculate GDP per capita. We find
English per capita income growth of 0.20 per cent per annum between 1270 and 1700,
although growth was episodic, with the strongest growth during the Black Death crisis of
the fourteenth century and in the second half of the seventeenth century. For the period
1700-1870, we find British per capita income growth of 0.48 per cent, broadly in line
with the widely accepted Crafts/Harley estimates. This modest trend growth in per capita
income since 1270 suggests that, working back from the present, living standards in the
late medieval period were well above âbare bones subsistenceâ. This can be reconciled
with modest levels of kilocalorie consumption per head because of the very large share of
pastoral production in agriculture
Pycortex: an interactive surface visualizer for fMRI.
Surface visualizations of fMRI provide a comprehensive view of cortical activity. However, surface visualizations are difficult to generate and most common visualization techniques rely on unnecessary interpolation which limits the fidelity of the resulting maps. Furthermore, it is difficult to understand the relationship between flattened cortical surfaces and the underlying 3D anatomy using tools available currently. To address these problems we have developed pycortex, a Python toolbox for interactive surface mapping and visualization. Pycortex exploits the power of modern graphics cards to sample volumetric data on a per-pixel basis, allowing dense and accurate mapping of the voxel grid across the surface. Anatomical and functional information can be projected onto the cortical surface. The surface can be inflated and flattened interactively, aiding interpretation of the correspondence between the anatomical surface and the flattened cortical sheet. The output of pycortex can be viewed using WebGL, a technology compatible with modern web browsers. This allows complex fMRI surface maps to be distributed broadly online without requiring installation of complex software
An efficient MPI/OpenMP parallelization of the Hartree-Fock method for the second generation of Intel Xeon Phi processor
Modern OpenMP threading techniques are used to convert the MPI-only
Hartree-Fock code in the GAMESS program to a hybrid MPI/OpenMP algorithm. Two
separate implementations that differ by the sharing or replication of key data
structures among threads are considered, density and Fock matrices. All
implementations are benchmarked on a super-computer of 3,000 Intel Xeon Phi
processors. With 64 cores per processor, scaling numbers are reported on up to
192,000 cores. The hybrid MPI/OpenMP implementation reduces the memory
footprint by approximately 200 times compared to the legacy code. The
MPI/OpenMP code was shown to run up to six times faster than the original for a
range of molecular system sizes.Comment: SC17 conference paper, 12 pages, 7 figure
Helium and Nitrogen Enrichment in Massive Main Sequence Stars: Mechanisms and Implications for the Origin of WNL Stars
The evolutionary paths taken by massive stars with remain substantially uncertain. They begin their lives as
main sequence (MS) O-stars. Depending on their masses, rotation rates, and
metallicities, they can then encounter a wide range of evolutionary states with
an equally broad set of possible surface compositions and spectral
classifications. We present a new grid of calculations for the evolution of
such stars that covers a broad range in mass, M/M to ,
rotation rate, to , metallicity,
to , and -element enhancement,
to . We show that rotating stars undergo
rotationally-induced dredge-up of nucleosynthetic products, mostly He and N, to
their surfaces while still on the MS. Non-rotating metal-rich stars also reveal
the products of nucleosynthesis on their surfaces because even modest amounts
of mass loss expose their "fossil" convective cores: regions that are no longer
convective, but which were part of the convective core at an early stage in the
star's evolution. Thus surface enhancement of He and N is expected for rotating
stars at all metallicities, and for non-rotating stars if they are relatively
metal-rich. We calculate a stellar atmosphere for a representative model from
our grid, properly accounting for He- and N-enhancement, and show that the
resulting spectrum provides a good match to observed WNL stars, strongly
suggesting that the physical mechanisms we have identified are the ultimate
cause of the WNL phase.Comment: 21 pages, 18 figures, 2 tables, accepted for publication in MNRAS, in
pres
- âŠ