70,744 research outputs found
Wage growth and job mobility in the United Kingdom and Germany
Using data from the British Household Panel Survey for 1991-99 and the German Socio-Economic Panel for 1984-99, the authors investigate job mobility and estimate the returns to tenure and experience. Job mobility was higher in the United Kingdom than in Germany. Returns to experience also seem to have been substantially higher in the United Kingdom, where the wage gain associated with ten years of labor market experience was around 80%, compared to 35% in Germany. The low returns to labor market experience in Germany appear to have been accountable to one group of workers: those with apprenticeship training, who tended to receive fairly high starting wages but to experience relatively low wage growth thereafter. Wage growth due to labor market experience was similar between the two countries for the other skill groups. Returns to tenure were close to zero in both countries
Heteroscedastic Gaussian processes for uncertainty modeling in large-scale crowdsourced traffic data
Accurately modeling traffic speeds is a fundamental part of efficient
intelligent transportation systems. Nowadays, with the widespread deployment of
GPS-enabled devices, it has become possible to crowdsource the collection of
speed information to road users (e.g. through mobile applications or dedicated
in-vehicle devices). Despite its rather wide spatial coverage, crowdsourced
speed data also brings very important challenges, such as the highly variable
measurement noise in the data due to a variety of driving behaviors and sample
sizes. When not properly accounted for, this noise can severely compromise any
application that relies on accurate traffic data. In this article, we propose
the use of heteroscedastic Gaussian processes (HGP) to model the time-varying
uncertainty in large-scale crowdsourced traffic data. Furthermore, we develop a
HGP conditioned on sample size and traffic regime (SRC-HGP), which makes use of
sample size information (probe vehicles per minute) as well as previous
observed speeds, in order to more accurately model the uncertainty in observed
speeds. Using 6 months of crowdsourced traffic data from Copenhagen, we
empirically show that the proposed heteroscedastic models produce significantly
better predictive distributions when compared to current state-of-the-art
methods for both speed imputation and short-term forecasting tasks.Comment: 22 pages, Transportation Research Part C: Emerging Technologies
(Elsevier
A nonlinear elliptic problem with terms concentrating in the boundary
In this paper we investigate the behavior of a family of steady state
solutions of a nonlinear reaction diffusion equation when some reaction and
potential terms are concentrated in a -neighborhood of a portion
of the boundary. We assume that this -neighborhood shrinks
to as the small parameter goes to zero. Also, we suppose
the upper boundary of this -strip presents a highly oscillatory
behavior. Our main goal here is to show that this family of solutions converges
to the solutions of a limit problem, a nonlinear elliptic equation that
captures the oscillatory behavior. Indeed, the reaction term and concentrating
potential are transformed into a flux condition and a potential on ,
which depends on the oscillating neighborhood
Foliations invariant by rational maps
We give a classification of pairs (F, f) where F is a holomorphic foliation
on a projective surface and f is a non-invertible dominant rational map
preserving F. We prove that both the map and the foliation are integrable in a
suitable sense.Comment: 17 pages. To appear in Math. Zeitshrift
Coupled electronic and morphologic changes in graphene oxide upon electrochemical reduction
Peer reviewedPostprin
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