37,375 research outputs found
Institutional features of wage bargaining in 23 European countries, the US and Japan.
This paper presents information on wage bargaining institutions, collected using a standardised questionnaire. Our data provide information from 1995 and 2006, for four sectors of activity and the aggregate economy, considering 23 European countries, plus the US and Japan. Main findings include a high degree of regulation in wage setting in most countries. Although union membership is low in many countries, union coverage is high and almost all countries also have some form of national minimum wage. Most countries negotiate wages on several levels, the sectoral level still being the most dominant, with an increasingly important role for bargaining at the firm level. The average length of collective bargaining agreements is found to lie between one and three years. Most agreements are strongly driven by developments in prices and eleven countries have some form of indexation mechanism which affects wages. Cluster analysis identifies three country groupings of wage-setting institutions.Wage Bargaining ; Institutions ; Indexation ; Trade Union Membership, Cluster Analysis
Fractional Quantum Hall Effect in Suspended Graphene: Transport Coefficients and Electron Interaction Strength
Strongly correlated electron liquids which occur in quantizing magnetic
fields reveal a cornucopia of fascinating quantum phenomena such as
fractionally charged quasiparticles, anyonic statistics, topological order, and
many others. Probing these effects in GaAs-based systems, where electron
interactions are relatively weak, requires sub-kelvin temperatures and
record-high electron mobilities, rendering some of the most interesting states
too fragile and difficult to access. This prompted a quest for new
high-mobility systems with stronger electron interactions. Recently,
fractional-quantized Hall effect was observed in suspended graphene (SG), a
free-standing monolayer of carbon, where it was found to persist up to T=10 K.
The best results in those experiments were obtained on micron-size flakes, on
which only two-terminal transport measurements could be performed. Here we pose
and solve the problem of extracting transport coefficients of a fractional
quantum Hall state from the two-terminal conductance. We develop a method,
based on the conformal invariance of two-dimensional magnetotransport, and
illustrate its use by analyzing the measurements on SG. From the temperature
dependence of longitudinal conductivity, extracted from the measured
two-terminal conductance, we estimate the energy gap of quasiparticle
excitations in the fractional-quantized nu=1/3 state. The gap is found to be
significantly larger than in GaAs-based structures, signaling much stronger
electron interactions in suspended graphene. Our approach provides a new tool
for the studies of quantum transport in suspended graphene and other nanoscale
systems
Electronic structure and Magnetism in BaMnAs and BaMnSb
We study the properties of ThCrSi structure BaMnAs and
BaMnSb using density functional calculations of the electronic and
magnetic as well experimental measurements on single crystal samples of
BaMnAs. These materials are local moment magnets with moderate band gap
antiferromagnetic semiconducting ground states. The electronic structures show
substantial Mn - pnictogen hybridization, which stabilizes an intermediate spin
configuration for the nominally Mn. The results are discussed in the
context of possible thermoelectric applications and the relationship with the
corresponding iron / cobalt / nickel compounds Ba(Fe,Co,Ni)As
On the iterated Crank-Nicolson for hyperbolic and parabolic equations in numerical relativity
The iterated Crank-Nicolson is a predictor-corrector algorithm commonly used
in numerical relativity for the solution of both hyperbolic and parabolic
partial differential equations. We here extend the recent work on the stability
of this scheme for hyperbolic equations by investigating the properties when
the average between the predicted and corrected values is made with unequal
weights and when the scheme is applied to a parabolic equation. We also propose
a variant of the scheme in which the coefficients in the averages are swapped
between two corrections leading to systematically larger amplification factors
and to a smaller numerical dispersion.Comment: 7 pages, 3 figure
Charm meson resonances in decays
Motivated by recent experimental results we reconsider semileptonic decays within a model which combines heavy quark symmetry and
properties of the chiral Lagrangian. We include excited charm meson states,
some of them recently observed, in our Lagrangian and determine their impact on
the charm meson semileptonic form factors. We find that the inclusion of
excited charm meson states in the model leads to a rather good agreement with
the experimental results on the shape of the form factor. We
also calculate branching ratios for all decays.Comment: 9 pages, 4 figures; minor corrections, added some discussion, version
as publishe
Magnetic Reversal Time in Open Long Range Systems
Topological phase space disconnection has been recently found to be a general
phenomenon in isolated anisotropic spin systems. It sets a general framework to
understand the emergence of ferromagnetism in finite magnetic systems starting
from microscopic models without phenomenological on-site barriers. Here we
study its relevance for finite systems with long range interacting potential in
contact with a thermal bath. We show that, even in this case, the induced
magnetic reversal time is exponentially large in the number of spins, thus
determining {\it stable} (to any experimental observation time) ferromagnetic
behavior. Moreover, the explicit temperature dependence of the magnetic
reversal time obtained from the microcanonical results, is found to be in good
agreement with numerical simulations. Also, a simple and suggestive expression,
indicating the Topological Energy Threshold at which the disconnection occurs,
as a real energy barrier for many body systems, is obtained analytically for
low temperature
Origin of the high piezoelectric response in PbZr(1-x)TixO3
High resolution x-ray powder diffraction measurements on poled PbZr(1-x)TixO3
(PZT) ceramic samples close to the rhombohedral-tetragonal phase boundary (the
so-called morphotropic phase boundary, MPB) have shown that for both
rhombohedral and tetragonal compositions, the piezoelectric elongation of the
unit cell does not occur along the polar directions but along those directions
associated with the monoclinic distortion. This work provides the first direct
evidence for the origin of the very high piezoelectricity in PZT.Comment: 4 pages, 4 EPS figures embedded. More specific title and abstract. To
appear in Phys. Rev. Let
Numerical simulation study of the dynamical behavior of the Niedermayer algorithm
We calculate the dynamic critical exponent for the Niedermayer algorithm
applied to the two-dimensional Ising and XY models, for various values of the
free parameter . For we regain the Metropolis algorithm and for
we regain the Wolff algorithm. For , we show that the mean
size of the clusters of (possibly) turned spins initially grows with the linear
size of the lattice, , but eventually saturates at a given lattice size
, which depends on . For , the Niedermayer
algorithm is equivalent to the Metropolis one, i.e, they have the same dynamic
exponent. For , the autocorrelation time is always greater than for
(Wolff) and, more important, it also grows faster than a power of .
Therefore, we show that the best choice of cluster algorithm is the Wolff one,
when compared to the Nierdermayer generalization. We also obtain the dynamic
behavior of the Wolff algorithm: although not conclusive, we propose a scaling
law for the dependence of the autocorrelation time on .Comment: Accepted for publication in Journal of Statistical Mechanics: Theory
and Experimen
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Evaluation of peak-picking algorithms for protein mass spectrometry
Peak picking is an early key step in MS data analysis. We compare three commonly used approaches to peak picking and discuss their merits by means of statistical analysis. Methods investigated encompass signal-to-noise ratio, continuous wavelet transform, and a correlation-based approach using a Gaussian template.
Functionality of the three methods is illustrated and discussed in a practical context using a mass spectral data set created with MALDI-TOF technology. Sensitivity and specificity are investigated using a manually defined reference set of peaks. As an additional criterion, the robustness of the three methods is assessed by a perturbation analysis and illustrated using ROC curves
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