Pollaris H.,Research group LogisticsAgoralaan |
Braekers K.,Research group LogisticsAgoralaan |
Caris A.,Research group LogisticsAgoralaan |
Janssens G.K.,Research group LogisticsAgoralaan |
And 2 more authors.
Networks | Year: 2017
In this article an Iterated Local Search algorithm for the capacitated vehicle routing problem with sequence-based pallet loading and axle weight constraints is presented. Axle weight limits impose a great challenge for transportation companies. Yet, the literature on the incorporation of axle weight constraints in vehicle routing models is very scarce. The effect of introducing axle weight constraints in a CVRP on total routing cost is analyzed. Results show that integrating axle weight constraints does not lead to a large cost increase. However, not including axle weight constraints in the planning process may induce major axle weight violations. © 2017 Wiley Periodicals, Inc.
Determinants of vitamin D status in young children: Results from the Belgian arm of the IDEFICS (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants) Study
Sioen I.,Ghent University |
Sioen I.,FWO Inc |
Mouratidou T.,University of Zaragoza |
Kaufman J.-M.,Ghent University |
And 9 more authors.
Public Health Nutrition | Year: 2012
Objective To describe the vitamin D status of Belgian children and examine the influence of non-nutritional determinants, in particular of anthropometric variables.Design Cross-sectional data of Belgian participants of the EU 6th Framework Programme IDEFICS (Identification and Prevention of Dietary- and Lifestyle-Induced Health Effects in Children and Infants) Study.Setting 25-Hydroxyvitamin D (25(OH)D) was measured using RIA. Vitamin D status was categorized as deficient (<25 nmol/l), insufficient (25-50 nmol/l), sufficient (50-75 nmol/l) and optimal (75 nmol/l). Anthropometric measurements included height, weight, waist and hip circumferences and triceps and subscapular skinfold thicknesses.Subjects Children (n 357) aged 4-11 years.Results Serum 25(OH)D ranged from 136 to 1235 nmol/l (mean 472 (sd 146) nmol/l); with 5 % deficient, 53 % insufficient, 40 % sufficient and 2 % optimal. No significant differences were found by age and gender. Significant differences in 25(OH)D were observed for month of sampling (P < 0001), number of hours playing outside per week (r = 0140), weight (r = 0121), triceps (r = 0112) and subscapular (r = 0119) skinfold thickness, sum of two skinfold thicknesses (r = 0125) and waist circumference (r = 0108). Linear regression analysis of 25(OH)D adjusted for age, month of sampling and hours playing outside per week suggested that (i) weight, (ii) BMI Z-score, (iii) waist circumference and (iv) triceps and subscapular skinfold thickness (as well as the sum of both) independently influenced 25(OH)D.Conclusions The majority of Belgian children had a suboptimal vitamin D status, with more than half having an insufficient status in winter and spring. Month of the year, weekly number of hours playing outside and body composition - both central and abdominal obesity - were identified as important determinants of vitamin D status in Belgian children. © 2011 The Authors.
Arts S.,Managerial Economics |
Arts S.,FWO Inc |
Appio F.P.,Sant'Anna School of Advanced Studies |
Van Looy B.,Managerial Economics |
And 2 more authors.
Scientometrics | Year: 2013
Since Schumpeter's (The theory of economic development, 1934) seminal work on economic development, innovation is considered as one of the main drivers of firm performance and economic growth. At the same time, technological innovations vary considerably in terms of impact with only a minority of new inventions contributing significantly to technological progress and economic growth. More recently a number of indicators derived from patent documents have been advanced to capture the nature and impact of technological inventions. In this paper, we compare and validate these indicators within the field of biotechnology. An extensive analysis of the recent history of biotechnology allows us to identify the most important inventions (n = 214) that shaped the field of biotechnology in the time period 1976-2001. A considerable number of these inventions have been patented between 1976 and 2001 (n = 117, 55 %). For all USPTO biotech patents filed between 1976 and 2001 (n = 84,119), relevant indicators have been calculated. In a subsequent step, we assess which indicators allow us to distinguish between the most important patented inventions and their less influential counterparts by means of logistic regression models. Our findings show that the use of multiple, complementary indicators provides the most comprehensive picture. In addition, it is clear that ex-post indicators reflecting impact and value outperform ex-ante indicators reflecting the nature and novelty of the invention in terms of precision and recall. © 2013 Akadémiai Kiadó, Budapest, Hungary.
Vasheghani Farahani S.,Catholic University of Leuven |
Nakariakov V.M.,University of Warwick |
Nakariakov V.M.,Russian Academy of Sciences |
Verwichte E.,University of Warwick |
And 2 more authors.
Astronomy and Astrophysics | Year: 2012
Aims. We study the efficiency of the energy transfer to shorter scales in the field-aligned direction-the parallel nonlinear cascade-that accompanies the propagation of torsional Alfvén waves along open magnetic fields in the solar and stellar coronae, and compare it with the same effects for the shear Alfvén wave. The evolution of the torsional Alfvén wave is caused by the back reaction of nonlinearly induced compressive perturbations on the Alfvén wave. Methods. The evolution of upwardly propagating torsional Alfvén waves is considered in terms of the second-order thin flux-tube approximation in a straight untwisted and non-rotating magnetic flux-tube. The Cohen-Kulsrud equation for weakly nonlinear torsional waves is derived. In the model, the effect of the cubic nonlinearity on the propagation of long-wavelength axisymmetric torsional waves is compared with the similar effect that accompanies the propagation of plane linearly-polarised (shear) Alfvén waves of small amplitude. Results. The solution to the Cohen-Kulsrud type equation for torsional waves shows that their evolution is independent of the plasma-β, which is in contrast to the shear Alfvén wave. In a finite-β plasma, the nonlinear evolution of torsional Alfvén waves is slower and the parallel nonlinear cascade is less efficient than those of shear Alfvén waves. These results have important implications for the analysis of possible heating of the plasma and its acceleration in the upper layers of solar and stellar coronae. In particular, one-dimensional models of coronal heating and wave acceleration, which use shear Alfvén waves instead of torsional Alfvén waves, over-estimate the efficiency of these processes. © 2012 ESO.
Ferranti F.,Vrije Universiteit Brussel |
Ferranti F.,FWO Inc |
Magnani A.,University of Naples Federico II |
D'Alessandro V.,University of Naples Federico II |
And 4 more authors.
IEEE Transactions on Components, Packaging and Manufacturing Technology | Year: 2015
We propose a parameterized macromodeling methodology to effectively and accurately carry out dynamic electrothermal (ET) simulations of electronic components and systems, while taking into account the influence of key design parameters on the system behavior. In order to improve the accuracy and to reduce the number of computationally expensive thermal simulations needed for the macromodel generation, a decomposition of the frequency-domain data samples of the thermal impedance matrix is proposed. The approach is applied to study the impact of layout variations on the dynamic ET behavior of a state-of-the-Art 8-finger AlGaN/GaN high-electron mobility transistor grown on a SiC substrate. The simulation results confirm the high accuracy and computational gain obtained using parameterized macromodels instead of a standard method based on iterative complete numerical analysis. © 2011-2012 IEEE.
Franco J.,IMEC |
Franco J.,Catholic University of Leuven |
Eneman G.,IMEC |
Eneman G.,FWO Inc |
And 4 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2011
Hot carrier (HC) reliability of Si-passivated, Ge channel, p -channel metal-oxide-semiconductor field-effect transitors (pMOSFETs) with a physical gate length of 70 nm is investigated in this article. HCs are reported to affect the reliability of these devices more than negative bias temperature instability, which is normally considered as the most serious reliability concern for Si p -channel field effect transistors. The impact of different halo implant conditions on the HC reliability of Ge pMOSFETs is then studied. High energy and high dose halo implants, while being very effective for threshold voltage adjustment of short-channel devices, can remarkably reduce device lifetime under HC stress condition due to the enhanced electric field peak near the drain side of the channel. HC reliability, therefore, should be carefully taken into account when optimizing halo implant conditions for Ge p -channel metal-oxide-semiconductor. © 2011 American Vacuum Society.
Vandenbroeck S.,Catholic University of Leuven |
De Geest S.,Catholic University of Leuven |
De Geest S.,University of Basel |
Zeyen T.,University Hospitals Leuven |
And 3 more authors.
Eye | Year: 2011
The aim of this review was to summarize literature in view of patient-reported outcome (PRO) instruments for glaucoma and provide guidance on how outcomes are best assessed based on evidence about their content and validity. A systematic literature review was performed on papers describing the developmental process and/or psychometric properties of glaucoma or vision-specific PRO-instruments. Each of them was assessed on their adherence to a framework of quality criteria. Fifty-three articles were identified addressing 27 PRO-instruments. In all, 18 PRO's were developed for glaucoma and 9 for diverse ophthalmologic conditions. Seven instruments addressed functional status, 11 instruments quality of life and 9 instruments disease and treatment-related factors. Most of the instruments demonstrated only partially adherence to predefined quality standards. The tools for assessing functional status were of poor quality, while the Glaucoma Quality of Life Questionnaire and the Vision Quality of Life Index were well-developed QoL measures, yet only validated using classical techniques. The Rasch-scaled QoL-tools, IVI and VCM1 need to improve their item-content for glaucoma patients. The questionnaires to measure adherence should improve their validity and the Treatment Satisfaction Survey for Intra Ocular Pressure pops out as the highest quality tool for measuring topical treatment side effects. This review revealed that most PRO-instruments demonstrated poor developmental quality, more specifically a lack of conceptual framework and item generation strategies not involving the patients perspective. Psychometric characteristics were mostly tested using classical validation techniques. © 2011 Macmillan Publishers Limited All rights reserved.
Mitard J.,IMEC |
Witters L.,IMEC |
Hellings G.,Catholic University of Leuven |
Krom R.,Catholic University of Leuven |
And 23 more authors.
IEEE Symposium on VLSI Circuits, Digest of Technical Papers | Year: 2011
A 2nd generation of Implant Free Quantum Well pFETs is presented in this work. SiGe25%-embedded Source/Drain was implemented, leading to an excellent short channel control and logic performance (1mA/um-ION@-1V). No narrow-width effect was found and a multi-VTH strategy is also offered. Performance of the strained-IFQW pFETs was finally demonstrated at lower V DD. © 2011 JSAP (Japan Society of Applied Physi.
Guariso A.,Catholic University of Leuven |
Guariso A.,University of Stockholm |
Squicciarini M.P.,Catholic University of Leuven |
Squicciarini M.P.,FWO Inc |
And 2 more authors.
Applied Economic Perspectives and Policy | Year: 2014
The recent spikes of global food prices induced a rapid increase in mass media coverage, public policy attention, and donor funding for food security and for agriculture and rural poverty. This has occurred while the shift from low to high food prices has induced a shift in (demographic or social) location of the hunger and poverty effects, but the total number of undernourished and poor people has declined over the same period. We suggest that the observed pattern can be explained by the presence of a global urban bias on agriculture and food policy in developing countries, and we discuss whether this global urban bias may actually benefit poor farmers. We argue that the food price spikes have succeeded where others have failed in the past: to move the problems of poor and hungry farmers to the top of the policy agenda and to induce development and donor strategies to help them. © The Author 2014.