201 research outputs found
Income support policies for part-time workers : a stepping-stone to regular jobs ? An application to young long-terme unemployed women in Belgium
We verify whether an income support policy for part-time workers in Belgium increases the transition from unemployment to non-subsidised, “regular” employment. Using a sample of 8630 long-term unemployed young women, whose labour market history is observed from 1998 to 2001, we implement the “timing of events approach proposed byAbbring et Van den Berg (2003) to control for selection effects. Our results suggest that the policy has a significantly positive effect on the transition to non-subsidised employment when one does not control for unobserved heterogeneity. This effect remains positive, but becomes insignificant, when one corrects for selection on unobservable characteristics.Active labour markets policies, Evaluation, Mixed Proportional Hazard Models
Dispersive wave emission and supercontinuum generation in a silicon wire waveguide pumped around the 1550 nm telecommunication wavelength
We experimentally and numerically study dispersive wave emission, soliton
fission and supercontinuum generation in a silicon wire at telecommunication
wavelengths. Through dispersion engineering, we experimentally confirm a
previously reported numerical study [1] and show that the emission of resonant
radiation from the solitons can lead to the generation of a supercontinuum
spanning over 500 nm. An excellent agreement with numerical simulations is
observed.Comment: 4 pages, 4 figure
Self phase modulation in Highly nonlinear hydrogenated amorphous silicon
We study self phase modulation in submicron amorphous silicon-on-insulator waveguides. We extract both the real and imaginary part of the nonlinear parameter gamma from a 1 cm long waveguide with a cross-section of 500x220nm(2). The real and imaginary part of the nonlinear parameter are found to be 767W(-1)m(-1) and -28W(-1)m(-1) respectively. The figure of merit (FOM) is found to be 3.6 times larger than the FOM in crystalline silicon (c-Si)
Micro-transfer printing of lithium niobate on silicon nitride
Successful micro-transfer printing of lithium niobate on a silicon nitride platform is demonstrated. A proof of concept electro-optical modulator is fabricated using this hybrid integration method which shows a half-wave voltage-length product VπLπ=5.5 Vcm and insertion losses of 7 dB
Nonlinear optical interactions in silicon waveguides
The strong nonlinear response of silicon photonic nanowire waveguides allows for the integration of nonlinear optical functions on a chip. However, the detrimental nonlinear optical absorption in silicon at telecom wavelengths limits the efficiency of many such experiments. In this review, several approaches are proposed and demonstrated to overcome this fundamental issue. By using the proposed methods, we demonstrate amongst others supercontinuum generation, frequency comb generation, a parametric optical amplifier, and a parametric optical oscillator
Medical image computing and computer-aided medical interventions applied to soft tissues. Work in progress in urology
Until recently, Computer-Aided Medical Interventions (CAMI) and Medical
Robotics have focused on rigid and non deformable anatomical structures.
Nowadays, special attention is paid to soft tissues, raising complex issues due
to their mobility and deformation. Mini-invasive digestive surgery was probably
one of the first fields where soft tissues were handled through the development
of simulators, tracking of anatomical structures and specific assistance
robots. However, other clinical domains, for instance urology, are concerned.
Indeed, laparoscopic surgery, new tumour destruction techniques (e.g. HIFU,
radiofrequency, or cryoablation), increasingly early detection of cancer, and
use of interventional and diagnostic imaging modalities, recently opened new
challenges to the urologist and scientists involved in CAMI. This resulted in
the last five years in a very significant increase of research and developments
of computer-aided urology systems. In this paper, we propose a description of
the main problems related to computer-aided diagnostic and therapy of soft
tissues and give a survey of the different types of assistance offered to the
urologist: robotization, image fusion, surgical navigation. Both research
projects and operational industrial systems are discussed
Visible-to-near-infrared octave spanning supercontinuum generation in a silicon nitride waveguide
The generation of an octave spanning supercontinuum covering 488-978 nm (at -30 dB) is demonstrated for the first time on-chip. This result is achieved by dispersion engineering a 1-cm-long Si3N4 waveguide and pumping it with an 100-fs Ti:Sapphire laser emitting at 795 nm. This work offers a bright broadband source for biophotonic applications and frequency metrology. © 2015 Optical Society of America.info:eu-repo/semantics/publishe
The LOFAR Transients Pipeline
Current and future astronomical survey facilities provide a remarkably rich
opportunity for transient astronomy, combining unprecedented fields of view
with high sensitivity and the ability to access previously unexplored
wavelength regimes. This is particularly true of LOFAR, a
recently-commissioned, low-frequency radio interferometer, based in the
Netherlands and with stations across Europe. The identification of and response
to transients is one of LOFAR's key science goals. However, the large data
volumes which LOFAR produces, combined with the scientific requirement for
rapid response, make automation essential. To support this, we have developed
the LOFAR Transients Pipeline, or TraP. The TraP ingests multi-frequency image
data from LOFAR or other instruments and searches it for transients and
variables, providing automatic alerts of significant detections and populating
a lightcurve database for further analysis by astronomers. Here, we discuss the
scientific goals of the TraP and how it has been designed to meet them. We
describe its implementation, including both the algorithms adopted to maximize
performance as well as the development methodology used to ensure it is robust
and reliable, particularly in the presence of artefacts typical of radio
astronomy imaging. Finally, we report on a series of tests of the pipeline
carried out using simulated LOFAR observations with a known population of
transients.Comment: 30 pages, 11 figures; Accepted for publication in Astronomy &
Computing; Code at https://github.com/transientskp/tk
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