2,319 research outputs found
Skills Obsolescence: Causes and Cures
Until now there has been surprisingly little research on the causes of and the remedies for skills obsolescence. This study tries to fill that gap to some extent by analysing the relation between risk factors and skills obsolescence. Moreover, the role remedies play to counter skills obsolescence is analysed. Four empirical analyses that relate skills obsolescence to risk factors and remedies are presented. We find that most risk factors identified in the literature can be validated empirically. The remedies for skills obsolescence are not effective in all situations: the results show that there is considerable variation in the effectiveness of the remedies across different types of skills obsolescence. Although current available data does not allow a comprehensive analysis, which also takes account of relations between the various types of skills obsolescence, the results obtained are plausible and offer a starting point for further research.education, training and the labour market;
A binary signature in the non-thermal radio-emitter Cyg OB2 #9
Aims: Non-thermal radio emission associated with massive stars is believed to
arise from a wind-wind collision in a binary system. However, the evidence of
binarity is still lacking in some cases, notably Cyg OB2 #9 Methods: For
several years, we have been monitoring this heavily-reddened star from various
observatories. This campaign allowed us to probe variations both on short and
long timescales and constitutes the first in-depth study of the visible
spectrum of this object. Results: Our observations provide the very first
direct evidence of a companion in Cyg OB2 #9, confirming the theoretical
wind-wind collision scenario. These data suggest a highly eccentric orbit with
a period of a few years, compatible with the 2yr-timescale measured in the
radio range. In addition, the signature of the wind-wind collision is very
likely reflected in the behaviour of some emission lines.Comment: accepted by A&A, 4 p, 3figure
Molecular biological methods for studying the gut microbiota : the EU human gut flora project
Seven European laboratories co-operated in a joint project (FAIR CT97-3035) to develop, refine and apply molecular methods towards facilitating elucidation of the complex composition of the human intestinal microflora and to devise robust methodologies for monitoring the gut flora in response to diet. An extensive database of 16S rRNA sequences for tracking intestinal bacteria was generated by sequencing the 16S rRNA genes of new faecal isolates and of clones obtained by amplification with polymerase chain reaction (PCR) on faecal DNA from subjects belonging to different age groups. The analyses indicated that the number of different species (diversity) present in the human gut increased with age. The sequence information generated, provided the basis for design of 16S rRNA-directed oligonucleotide probes to specifically detect bacteria at various levels of phylogenetic hierarchy. The probes were tested for their specificity and used in whole-cell and dot-blot hybridisations. The applicability of the developed methods was demonstrated in several studies and the major outcomes are described
Non-thermal radio emission from O-type stars. IV. Cyg OB2 No. 8A
We study the non-thermal radio emission of the binary Cyg OB2 No. 8A, to see
if it is variable and if that variability is locked to the orbital phase. We
investigate if the synchrotron emission generated in the colliding-wind region
of this binary can explain the observations and we verify that our proposed
model is compatible with the X-ray data. We use both new and archive radio data
from the Very Large Array (VLA) to construct a light curve as a function of
orbital phase. We also present new X-ray data that allow us to improve the
X-ray light curve. We develop a numerical model for the colliding-wind region
and the synchrotron emission it generates. The model also includes free-free
absorption and emission due to the stellar winds of both stars. In this way we
construct artificial radio light curves and compare them with the observed one.
The observed radio fluxes show phase-locked variability. Our model can explain
this variability because the synchrotron emitting region is not completely
hidden by the free-free absorption. In order to obtain a better agreement for
the phases of minimum and maximum flux we need to use stellar wind parameters
for the binary components which are somewhat different from typical values for
single stars. We verify that the change in stellar parameters does not
influence the interpretation of the X-ray light curve. Our model has trouble
explaining the observed radio spectral index. This could indicate the presence
of clumping or porosity in the stellar wind, which - through its influence on
both the Razin effect and the free-free absorption - can considerably influence
the spectral index. Non-thermal radio emitters could therefore open a valuable
pathway to investigate the difficult issue of clumping in stellar winds.Comment: 19 pages, 10 figures, accepted by A&
Low-crosstalk bifurcation detectors for coupled flux qubits
We present experimental results on the crosstalk between two AC-operated
dispersive bifurcation detectors, implemented in a circuit for high-fidelity
readout of two strongly coupled flux qubits. Both phase-dependent and
phase-independent contributions to the crosstalk are analyzed. For proper
tuning of the phase the measured crosstalk is 0.1 % and the correlation between
the measurement outcomes is less than 0.05 %. These results show that
bifurcative readout provides a reliable and generic approach for multi-partite
correlation experiments.Comment: Copyright 2010 American Institute of Physics. This article may be
downloaded for personal use only. Any other use requires prior permission of
the author and the American Institute of Physics. The following article
appeared in Applied Physics Letters and may be found at
http://link.aip.org/link/?apl/96/12350
Psychiatric comorbidity and causal disease models
In psychiatry, comorbidity is the rule rather than the exception. Up to 45% of all patients are classified as having more than one psychiatric disorder. These high rates of comorbidity have led to a debate concerning the interpretation of this phenomenon. Some authors emphasize the problematic character of the high rates of comorbidity because they indicate absent zones of rarities. Others consider comorbid conditions to be a validator for a particular reclassification of diseases. In this paper we will show that those at first sight contrasting interpretations of comorbidity are based on similar assumptions about disease models. The underlying ideas are that firstly high rates of comorbidity are the result of the absence of causally defined diseases in psychiatry, and second that causal disease models are preferable to non-causal disease models. We will argue that there are good reasons to seek after causal understanding of psychiatric disorders, but that causal disease models will not rule out high rates of comorbidity-neither in psychiatry, nor in medicine in general. By bringing to the fore these underlying assumptions, we hope to clear the ground for a different understanding of comorbidity, and of models for psychiatric diseases. (C) 2012 Elsevier Inc. All rights reserved.</p
Overschakelen van biggenkorrel naar startvoer op 18 kg
Op het Varkensproefbedrijf 'Zuid- en West-Nederland' in Sterksel is onderzoek verricht naar het verstrekken van startvoer tijdens de biggenopfok, vanaf een lichaamsgewicht van 18 kg
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