1,825 research outputs found
Internal Migration and Regional Population Dynamics in Europe: Sweden Case Study
This paper describes the structure of internal migration and population change in Sweden in recent decades, focussing on the years 1988 and 1998 to capture change in the last decade.
Up to the 1970s and again in the early 1990s natural increase play an important role in regional population dynamics. In the late 1990s growing international migration, decreasing fertility and strong net internal migration into large cities increased the importance of migration at both national and local levels. In 1988 migration flows contributed to a pattern of relatively even deconcentration of population. Urban centres and surrounding communities experienced mixed patterns of growth. The pattern observed in 1998 was entirely different. It showed a strong movement up the urban hierarchy. Rural and remote areas, especially those in Norrland, depopulated. In 1998 migrants moved from low-density areas to high-density. High density areas had much higher population gains than low density over the 1988â1998 period.
There is a difference in migration pattern between the north of the country, which mostly loses population and the central and southern parts, which mostly gain people. The pattern of migration of the Swedish population is, to large extent, related to the level of unemployment. Low unemployment areas attract migrants; high unemployment areas lose them. However, the level of unemployment cannot be considered in isolation, because the level of unemployment is correlated with the level of urbanisation and with type of regional economy. Areas with an educated population have a very strong attraction for migrants. A high level of education is indispensable for high level services, including tertiary education, and for high technology enterprises, which attract migrants. Young people migrate to metropolitan areas and university towns out of the other types of municipality. Medium sized municipalities attract families. Outflows from industrial regions and Inner Norrland municipalities are visible in all age groups. Metropolitan areas are gaining popularity among families. The elderly population migrates to university and medium size municipalities
Next-to-leading order diphoton+2-jet production at the LHC
We present results from a recent calculation of prompt photon-pair production
in association with two jets to next-to-leading order (NLO) at the LHC. The
virtual contribution is evaluated using the BlackHat library, a numerical
implementation of on-shell methods for one-loop amplitudes, in conjunction with
SHERPA. We study four sets of cuts: standard jet cuts, a set of Higgs-related
cuts suggested by ATLAS, and corresponding sets which isolate the kinematic
region where the process becomes the largest background to Higgs production via
vector-boson fusion.Comment: 10 pages, 4 figures, Presented at 11th International Symposium on
Radiative Corrections (RADCOR 2013), 22-27 September 2013, Lumley Castle
Hotel, Durham, U
Anomalous relaxation kinetics of biological lattice-ligand binding models
We discuss theoretical models for the cooperative binding dynamics of ligands
to substrates, such as dimeric motor proteins to microtubules or more extended
macromolecules like tropomyosin to actin filaments. We study the effects of
steric constraints, size of ligands, binding rates and interaction between
neighboring proteins on the binding dynamics and binding stoichiometry.
Starting from an empty lattice the binding dynamics goes, quite generally,
through several stages. The first stage represents fast initial binding closely
resembling the physics of random sequential adsorption processes. Typically
this initial process leaves the system in a metastable locked state with many
small gaps between blocks of bound molecules. In a second stage the gaps
annihilate slowly as the ligands detach and reattach. This results in an
algebraic decay of the gap concentration and interesting scaling behavior. Upon
identifying the gaps with particles we show that the dynamics in this regime
can be explained by mapping it onto various reaction-diffusion models. The
final approach to equilibrium shows some interesting dynamic scaling
properties. We also discuss the effect of cooperativity on the equilibrium
stoichiometry, and their consequences for the interpretation of biochemical and
image reconstruction results.Comment: REVTeX, 20 pages, 17 figures; review, to appear in Chemical Physics;
v2: minor correction
NLO merging in tt+jets
In this talk the application of the recently introduced methods to merge NLO
calculations of successive jet multiplicities to the production of top pairs in
association with jets will be discussed, in particular a fresh look is taken at
the top quark forward-backward asymmetries. Emphasis will be put on the
achieved theoretical accuracy and the associated perturbative and
non-perturbative error estimates.Comment: 6 pages, 3 figures, proceedings contribution for EPS 2013, Stockholm,
17-24 Jul
Next-to-Leading Order W + 5-Jet Production at the LHC
We present next-to-leading order QCD predictions for the total cross section
and for a comprehensive set of transverse-momentum distributions in W + 5-jet
production at the Large Hadron Collider. We neglect the small contributions
from subleading-color virtual terms, top quarks and some terms containing four
quark pairs. We also present ratios of total cross sections, and use them to
obtain an extrapolation formula to an even larger number of jets. We include
the decay of the boson into leptons. This is the first such computation
with six final-state vector bosons or jets. We use BlackHat together with
SHERPA to carry out the computation.Comment: RevTex, 27 pages, 7 figures, v2 minor corrections and corrected
reference
Left-Handed W Bosons at the LHC
The production of W bosons in association with jets is an important
background to new physics at the LHC. Events in which the W carries large
transverse momentum and decays leptonically lead to large missing energy and
are of particular importance. We show that the left-handed nature of the W
coupling, combined with valence quark domination at a pp machine, leads to a
large left-handed polarization for both W^+ and W^- bosons at large transverse
momenta. The polarization fractions are very stable with respect to QCD
corrections. The leptonic decay of the W bosons translates the common
left-handed polarization into a strong asymmetry in transverse momentum
distributions between positrons and electrons, and between neutrinos and
anti-neutrinos (missing transverse energy). Such asymmetries may provide an
effective experimental handle on separating W + jets from top quark production,
which exhibits very little asymmetry due to C invariance, and from various
types of new physics.Comment: 32 pages, revtex, 17 figures, 3 tables, v2 minor corrections to ME+PS
results, no changes to conclusions, added reference
The one-loop six-dimensional hexagon integral with three massive corners
We compute the six-dimensional hexagon integral with three non-adjacent
external masses analytically. After a simple rescaling, it is given by a
function of six dual conformally invariant cross-ratios. The result can be
expressed as a sum of 24 terms involving only one basic function, which is a
simple linear combination of logarithms, dilogarithms, and trilogarithms of
uniform degree three transcendentality. Our method uses differential equations
to determine the symbol of the function, and an algorithm to reconstruct the
latter from its symbol. It is known that six-dimensional hexagon integrals are
closely related to scattering amplitudes in N=4 super Yang-Mills theory, and we
therefore expect our result to be helpful for understanding the structure of
scattering amplitudes in this theory, in particular at two loops.Comment: 15 pages, 2 figure
Report of the 2005 Snowmass Top/QCD Working Group
This report discusses several topics in both top quark physics and QCD at an
International Linear Collider (ILC). Issues such as measurements at the
threshold, including both theoretical and machine requirements, and
the determination of electroweak top quark couplings, are reviewed. New results
concerning the potential of a 500 GeV collider for measuring
couplings and the top quark Yukawa coupling are presented. The status of higher
order QCD corrections to jet production cross sections, heavy quark form
factors, and longitudinal gauge boson scattering, needed for percent-level
studies at the ILC, are reviewed. A new study of the measurement of the
hadronic structure of the photon at a collider is presented. The
effects on top quark properties from several models of new physics, including
composite models, Little Higgs theories, and CPT violation, are studied.Comment: 39 pages, many figs; typos fixed and refs added. Contributed to the
2005 International Linear Collider Physics and Detector Workshop and 2nd ILC
Accelerator Workshop, Snowmass, Colorado, 14-27 Aug 200
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