1,573 research outputs found
How do employers cope with an ageing workforce?
How age-conscious are human resource policies? Using a survey of Dutch employers, we examine how employers deal with the prospect of an ageing work force. We supplement our analysis with an additional survey of Dutch employees to compare human resource policies to practices. Results show that a small minority of employers are taking measures to enhance productivity (training programmes) or bring productivity in line with pay (demotion). Personnel policies tend to ‘spare’ older workers: giving them extra leave, early retirement, or generous employment protection: older workers who perform poorly are allowed to stay, whereas younger workers under similar conditions are dismissed.age/aging, employers, productivity, stereotypes
Seabird metapopulations: searching for alternative breeding habitats
Today, many seabird species nest in port areas, which are also necessary for human economic activity. In this paper, we evaluate, using a metapopulation model, the possibilities for creating alternative breeding sites for the Common Tern (Sterna hirundo) in the Rhine¿Meuse¿Scheldt estuary. We explore 22 scenarios that differ with respect to (1) loss of breeding habitat in port areas, (2) location and size of newly created habitat, and (3) coexistence of old and new habitat. Results indicate that loss of port area habitats results in a serious 41% decline in the breeding population. When the loss in ports is compensated for within the ports, the decline was negligible. Fourteen scenarios result in an increase of the Common Tern metapopulation. In these, extra breeding habitat is created outside the ports in fish-rich waters, resulting in a potential metapopulation increase of 25%. However, the period of overlap between lost and newly created habitat strongly affects the results. A gap between the removal of old and the creation of new breeding areas might cause a drop in the metapopulation level of 30%. The population recovery from this drop might take more than 100 years due to slow recolonization. Our results suggest that conservation of seabird species should be evaluated on a metapopulation scale and that the creation of new habitat may help to compensate for habitat loss in other areas. Furthermore, the results indicate that overlap between the existence of old and newly created breeding habitats is crucial for the success of compensation efforts. However, new locations should be carefully selected, because not only is the suitability of the breeding grounds important, but ample fish availability nearby is also ke
Size and Causes of the Occupational Gender Wage-gap in the Netherlands
Research from the United States consistently shows that female-dominated occupations generally yield lower wages than male-dominated occupations. Using detailed occupational data, this study analyses the size andcauses of this occupational genderwage-gap in the Dutch labourmarket using multi-levelmodelling techniques.The analyses showthat bothmen andwomen earn lowerwages if they are employed in female-dominated occupations. This especially indicates the signi¢cance of gender inWestern labour markets, since overall levels of wage inequality are relatively small in the Netherlands compared to, for example, the United Kingdom and the United States. Di¡erences in required responsibility are particularly important in accounting for this occupational wage-gap. Nonetheless, we find large wage penalties for working in a female-dominated instead of a maledominated occupation for occupations that require high levels of education, skills, and responsibility.
Multiple grid methods for the solution of Fredholm integral equations of the second kind
Conformal phased array with beam forming for airborne satellite communication
For enhanced communication on board of aircraft novel antenna systems with broadband satellite-based capabilities are required. The installation of such systems on board of aircraft requires the development of a very low-profile aircraft antenna, which can point to satellites anywhere in the upper hemisphere. To this end, phased array antennas which are conformal to the aircraft fuselage are attractive. In this paper two key aspects of conformal phased array antenna arrays are addressed: the development of a broadband Ku-band antenna and the beam synthesis for conformal array antennas. The antenna elements of the conformal array are stacked patch antennas with dual linear polarization which have sufficient bandwidth. For beam forming synthesis a method based on a truncated Singular Value Decomposition is proposed
Interference effects in the photorecombination of argonlike Sc3+ ions: Storage-ring experiment and theory
Absolute total electron-ion recombination rate coefficients of argonlike
Sc3+(3s2 3p6) ions have been measured for relative energies between electrons
and ions ranging from 0 to 45 eV. This energy range comprises all dielectronic
recombination resonances attached to 3p -> 3d and 3p -> 4s excitations. A broad
resonance with an experimental width of 0.89 +- 0.07 eV due to the 3p5 3d2 2F
intermediate state is found at 12.31 +- 0.03 eV with a small experimental
evidence for an asymmetric line shape. From R-Matrix and perturbative
calculations we infer that the asymmetric line shape may not only be due to
quantum mechanical interference between direct and resonant recombination
channels as predicted by Gorczyca et al. [Phys. Rev. A 56, 4742 (1997)], but
may partly also be due to the interaction with an adjacent overlapping DR
resonance of the same symmetry. The overall agreement between theory and
experiment is poor. Differences between our experimental and our theoretical
resonance positions are as large as 1.4 eV. This illustrates the difficulty to
accurately describe the structure of an atomic system with an open 3d-shell
with state-of-the-art theoretical methods. Furthermore, we find that a
relativistic theoretical treatment of the system under study is mandatory since
the existence of experimentally observed strong 3p5 3d2 2D and 3p5 3d 4s 2D
resonances can only be explained when calculations beyond LS-coupling are
carried out.Comment: 11 pages, 7 figures, 3 tables, Phys. Rev. A (in print), see also:
http://www.strz.uni-giessen.de/~k
Single-photon single ionization of W ions: experiment and theory
Experimental and theoretical results are reported for photoionization of
Ta-like (W) tungsten ions. Absolute cross sections were measured in the
energy range 16 to 245 eV employing the photon-ion merged-beam setup at the
Advanced Light Source in Berkeley. Detailed photon-energy scans at 100 meV
bandwidth were performed in the 16 to 108 eV range. In addition, the cross
section was scanned at 50 meV resolution in regions where fine resonance
structures could be observed. Theoretical results were obtained from a
Dirac-Coulomb R-matrix approach. Photoionization cross section calculations
were performed for singly ionized atomic tungsten ions in their , =1/2, ground level and the associated
excited metastable levels with =3/2, 5/2, 7/2 and 9/2. Since the ion beams
used in the experiments must be expected to contain long-lived excited states
also from excited configurations, additional cross-section calculations were
performed for the second-lowest term, 5d^5 \; ^6{\rm S}_{J}, =5/2, and for
the F term, 5d^3 6s^2 \; ^4{\rm F}_{J}, with = 3/2, 5/2, 7/2 and 9/2.
Given the complexity of the electronic structure of W the calculations
reproduce the main features of the experimental cross section quite well.Comment: 23 pages, 7 figures, 1 table: Accepted for publication in J. Phys. B:
At. Mol. & Opt. Phy
Dynamics of plant communities in field boundaries : restoration of biodiversity
The field boundary, the strip of semi-natural vegetation bordering arable fields, can be considered as an important area for plant species survival in landscapes dominated by agriculture. In the last decennia, the natural plant species diversity has been reduced in many agricultural landscapes. Therefore, the objective of this thesis is to analyse factors determining biodiversity in field boundaries such as nutrient deposition from the arable field, mowing regime, level of disturbance and boundary dimensions. For this purpose a simulation model was constructed that comprises the processes and factors that determine the dynamics of the field boundary vegetation.This model is the result of the integration of three new models: a plant competition model based on eco-physiological principles, a spatially explicit population dynamical model and a seed dispersal model. The models were parameterized and evaluated with experimental data that were largely obtained from experiments described this thesis. Experimental research, therefore, was focussed on plant characteristics determining competition, succession and dispersal. Simulations and experimental results indicated that to enhance the diversity of the field boundary vegetation the following measures should be taken:Preventing all nutrient inputs from the arable field.Mowing and removal of the cuttings.Keeping the disturbance level under 20% of the area (y-1).Keeping the boundary as wide as possible but at at least wider than the maximum fertilizer misplacement.</ol
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