1,672 research outputs found
Proof firm downsizing and diagnosis-specific disability pensioning in Norway
<br>Background: We wanted to investigate if firm downsizing is related to an increased rate of disability pensions among the former employed, especially for those with musculoskeletal and psychiatric diagnoses, and for those having to leave the firm.</br>
<br>Methods: Statistics Norway provided a linked file with demographic information and all social security grants from the National Insurance Administration for 1992ā2004 for all inhabitants in Norway. Our sample was aged 30ā55 years in 1995, being alive, employed and not having a disability pension at the end of 2000. Downsizing was defined as percent change in number of employed per firm from 1995 to end 2000. Employment data were missing for 25.6% of the sample.</br>
<br>Results: Disability pension rates in the next four years were 25% higher for those experiencing a 30-59% downsizing than for those not experiencing a reduction of the workforce. 1-29% and 60-100% downsizing did not have this effect. Stayers following down-sizing had higher disability pension rates than leavers. What we have called complex musculoskeletal and psychiatric diagnoses were relatively most common.</br>
<br>Conclusion: Moderate downsizing is followed by a significant increase in disability pension rates in the following four years, often with complex musculoskeletal and psychiatric diagnoses.</br>
Investigation of topographical stability of the concave and convex Self-Organizing Map variant
We investigate, by a systematic numerical study, the parameter dependence of
the stability of the Kohonen Self-Organizing Map and the Zheng and Greenleaf
concave and convex learning with respect to different input distributions,
input and output dimensions
Analysis of rainfall records: possible relation to self-organized criticality
The hypothesis that rainfall might be a case of self-organized critical dynamics is tested using long-term data sets from weather stations around the world. It is found that the distribution of droughts in semi-arid regions obeys indeed a clear-cut power law. The statistics for rain intensity, on the other hand, exhibits two distinct scaring regimes. (C) 1998 Elsevier Science B.V. All rights reserved
Stability borders of feedback control of delayed measured systems
When stabilization of unstable periodic orbits or fixed points by the method
given by Ott, Grebogi and Yorke (OGY) has to be based on a measurement delayed
by orbit lengths, the performance of unmodified OGY method is expected
to decline. For experimental considerations, it is desired to know the range of
stability with minimal knowledge of the system. We find that unmodified OGY
control fails beyond a maximal Ljapunov number of
. In this paper the area of stability is
investigated both for OGY control of known fixed points and for difference
control of unknown or inaccurately known fixed points. An estimated value of
the control gain is given. Finally we outline what extensions have to be
considered if one wants to stabilize fixed points with Ljapunov numbers above
.Comment: 5 pages LaTeX using revtex and epsfig (4 figs included). Revised
versio
Enhanced Dimer Relaxation in an Atomic/Molecular BEC
We derive a universal formula for the rate constant \beta for relaxation of a
shallow dimer into deeply-bound diatomic molecules in the case of atoms with a
large scattering length a. We show that \beta is determined by a and by two
3-body parameters that also determine the binding energies and widths of Efimov
states. The rate constant \beta scales like \hbar a/m near the resonance, but
the coefficient is a periodic function of ln(a) that may have resonant
enhancement at values of a that differ by multiples of 22.7.Comment: 5 pages, revtex4, 2 PS figures, title changed, final versio
A Geometric Tension Dynamics Model of Epithelial Convergent Extension
Epithelial tissue elongation by convergent extension is a key motif of animal
morphogenesis. On a coarse scale, cell motion resembles laminar fluid flow; yet
in contrast to a fluid, epithelial cells adhere to each other and maintain the
tissue layer under actively generated internal tension. To resolve this
apparent paradox, we formulate a model in which tissue flow occurs through
adiabatic remodelling of the cellular force balance causing local cell
rearrangement. We propose that the gradual shifting of the force balance is
caused by positive feedback on myosin-generated cytoskeletal tension. Shifting
force balance within a tension network causes active T1s oriented by the global
anisotropy of tension. Rigidity of cells against shape changes converts the
oriented internal rearrangements into net tissue deformation. Strikingly, we
find that the total amount of tissue extension depends on the initial magnitude
of anisotropy and on cellular packing order. T1s degrade this order so that
tissue flow is self-limiting. We explain these findings by showing that
coordination of T1s depends on coherence in local tension configurations,
quantified by a certain order parameter in tension space. Our model reproduces
the salient tissue- and cell-scale features of germ band elongation during
Drosophila gastrulation, in particular the slowdown of tissue flow after
approximately twofold extension concomitant with a loss of order in tension
configurations. This suggests local cell geometry contains morphogenetic
information and yields predictions testable in future experiments. Furthermore,
our focus on defining biologically controlled active tension dynamics on the
manifold of force-balanced states may provide a general approach to the
description of morphogenetic flow.Comment: 44 pages, 19 figure
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