151 research outputs found
Testing Koopmans spectral functionals on the analytically solvable Hooke's atom
No full textKoopmans spectral functionals are a class of orbital-density-dependent functionals designed to accurately predict spectroscopic properties. They do so markedly better than their Kohn-Sham density-functional theory counterparts, as demonstrated in earlier works on benchmarks of molecules and bulk systems. This work is a complementary study where-instead of comparing against real, many-electron systems-we test Koopmans spectral functionals on Hooke's atom, a toy two-electron system that has analytical solutions for particular strengths of its harmonic confining potential. As these calculations clearly illustrate, Koopmans spectral functionals do an excellent job of describing Hooke's atom across a range of confining potential strengths. This work also provides broader insights into the features and capabilities of Koopmans spectral functionals more generally. (c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).THEO
Horizontal integration in markets for complementary components and vertical product differentiation: A case-based analysis in the semiconductor industry
No full textObservations of recent mergers and acquisitions (M&A) in the semiconductor and computer industry indicate that activities concentrate on the technology leaders in this market. The author examines the influence of players’ heterogeneous product technologies on their involvement in M&A. He provides a rationale for the influence with the help of a case study and a two-stage non cooperative game. The case is about an acquisition wave between suppliers in two semiconductor component markets. Exemplary for the whole industry, acquisition activities concentrated on the technology leader in one of the component markets. Technological heterogeneity is represented within a vertically differentiated product space in the model
Using a Social Experiment to Validate a Dynamic Behavioral Model of Child Schooling and Fertility: Assessing the Impact of a School Subsidy Program in Mexico
No full textThis paper studies the performance of a methodology that can be used to evaluate the impact of new policies that radically depart from existing ones. It uses data gathered from a randomized schooling subsidy experiment in Mexico (i) to estimate and validate a dynamic behavioral model of parental decisions about fertility and child schooling, (ii) to forecast long-term program impacts that extend beyond the life of the experiment, and (iii) to assess the impact of a variety of counterfactual policies. The behavioral model is estimated using data on families in the randomized-out control group and in the treatment group prior to the experiment, both of which did not receive any subsidy. Child wages provide a valuable source of variation in the data for identifying subsidy effects. Using the estimated model, we predict the effects of school subsidies according to the schedule that was implemented under the Mexican PROGRESA program.schooling, child labor, fertility, structural estimation, social experiments
Do Financial Bonuses to Employees Reduce their Absenteeism? Outcome of a Lottery
No full textIn this paper, we present evidence on the effect of greater numbers of police personnel on victimisation of crime and experience of nuisance. We make use of individual data from a Dutch victimisation survey unique in its size, duration and scope. By using individual victimisation data we provide evidence on the effects of police on nuisance rather than 'hard crime' only, we circumvent measurement error common to police statistics, and we are able to control for both individual and municipality characteristics.Technology, Policy and Managemen
Recurrence of sickness absence : a longitudinal study
No full textHalf of the employees with frequent episodes of sickness absence (4 times or more a year) or employees with long-term sickness absence (more than 6 weeks) had a long-term episode of sickness absence in the following 4 years, compared to a quarter of the employees with no previous frequent or long-term sickness absence (the reference group). 61% of the employees with frequent sickness absence had a recurrence, compared to 16% in the reference group. Moreover, employees with frequent episodes of sickness absence have a higher risk of work disability: 11% compared to 4% in the reference group. In employees with long-term sickness absence this risk is 26%. Risk groups are women, the elderly and employees with a lower salary. Employees with frequent or long-term sickness absence have a higher risk of leaving their employment: 26% compared to 19% in the reference group. Moreover, they more often leave their employment involuntarily, whereas employees in the reference group more often resign. Sickness absence due to mental disorders has a high risk of recurrence. The risk of sickness absence due to mental disorders is higher in women than in men, but both genders have similar recurrence risks. The health and work functioning of employees in the risk groups for long-term or recurrent sickness absence should be checked regularly. Employees who have been absent due to common mental disorders should be offered a relapse prevention consultation 3 months after they return to work, in order to prevent a recurrence. Monitoring should be continued for approximately 3 years, which is the period during which a recurrence usually takes place
De leefomgeving in maatschappelijke kosten-batenanalyses van transportprojecten
No full textEen analyse van 54 Nederlandse maatschappelijke kostenbatenanalyses (MKBA’s) van transportprojecten uit de periode 2000 tot 2011 laat zien dat het meenemen van de leefomgevingseffecten verbeterd kan worden. De criteria van ‘good practice’ voor het meenemen van leefomgevingseffecten zijn afgeleid van debatten in de wetenschappelijke literatuur. De 54 MKBA’s blijken behoorlijk compleet in het meenemen van leefomgevingseffecten van transportprojecten maar de MKBA-praktijk worstelt met het hangen van een prijskaartje aan leefomgevingseffecten en met een heldere presentatie van de effecten. Consequenties van wetenschappelijke debatten over de grote onzekerheden in de methoden om leefomgevingseffecten uit te drukken in een prijs en over disconteren in relatie tot het concept van duurzaamheid, worden nauwelijks teruggevonden in de huidige MKBApraktijk. Aanbevelingen worden gedaan om de praktijk te verbeteren.Infrastructures, Systems and ServicesTechnology, Policy and Managemen
Parametric hazard rate models for long-term sickness absence
No full textPURPOSE: In research on the time to onset of sickness absence and the duration of sickness absence episodes, Cox proportional hazard models are in common use. However, parametric models are to be preferred when time in itself is considered as independent variable. This study compares parametric hazard rate models for the onset of long-term sickness absence and return to work. METHOD: Prospective cohort study on sickness absence with four follow-up years of 53,830 employees working in the private sector in the Netherlands. The time to onset of long-term (>6 weeks) sickness absence and return to work were modelled by parametric hazard rate models. RESULTS: The exponential parametric model with a constant hazard rate most accurately described the time to onset of long-term sickness absence. Gompertz-Makeham models with monotonically declining hazard rates best described return to work. CONCLUSIONS: Parametric models offer more possibilities than commonly used models for time-dependent processes as sickness absence and return to work. However, the advantages of parametric models above Cox models apply mainly for return to work and less for onset of long-term sickness absence
Catalysing the energy service market: The role of intermediaries
No full textAbstractThe UK market for energy service contracts is expanding, owing in part to the emergence of intermediaries for those contracts in different parts of the public sector. These intermediaries combine a legal framework for establishing contracts with an organisational framework that facilitates contract negotiation and execution. This paper examines the nature and operation of these intermediaries in more detail, including their achievements to date and their similarities and differences. It uses ideas from transaction cost economics to develop a theoretical model of the contracting decision and shows how intermediary organisations can lower the transaction costs incurred by both clients and contractors, thereby increasing the viability of contracting. The paper argues that intermediaries can play an important role in expanding the market for energy service contracts, and hence in delivering cost-effective energy efficiency improvements throughout the public sector
Erratum - Development of a practice guideline for optimal symptom relief for patients with pneumonia and dementia in nursing homes using a Delphi study (vol 30, pg 487, 2015)
No full textvan der Maaden T, van der Steen JT, de Vet HCW, Achterberg WP, Boersma F, Schols JMGA, van Berkel JFJM, Mehr DR, Arcand M, Hoepelman AIM, Koopmans RTCM and Hertogh CMPM. Development of a practice guideline for optimal symptom relief for patients with pneumonia and dementia in nursing homes using a Delphi study. Int J Geriatr Psychiatry. 2015; 30: 487–496. https://doi.org/10.1002/gps.4167 In the above mentioned article, the Supporting Information uploaded in the Journal website was incorrect. The author has provided the appropriate file and this has been updated
NT-proBNP level before primary PCI and risk of poor myocardial reperfusion: Insight from the On-TIME II trial
No full textBackground: N-terminal fragment of the brain natriuretic peptide prohormone (NT-proBNP), a marker for neurohumoral activation, has been associated with adverse outcome in patients with myocardial infarction. NT-proBNP levels may reflect extensive ischemia and microvascular damage, therefore we investigated the potential association between baseline NT-proBNP level and ST-resolution (STR), a marker of myocardial reperfusion, after primary percutaneous coronary intervention (pPCI). Methods: we performed a post-hoc analysis of the On-TIME II trial (which randomized ST-elevation myocardial infarction (STEMI) patients to pre-hospital tirofiban administration vs placebo). Patients with measured NT-proBNP before angiography were included. Multivariate logistic-regression analyses was performed to investigate the association between baseline NTproBNP level and STR one hour after pPCI. Results: Out of 984 STEMI patients, 918 (93.3%) had NT-proBNP values at baseline. Patients with STR 70%) [Mean ±SD 375.2 ±1021.7 vs 1007.4 ±2842.3, Median (IQR) 111.7 (58.4-280.0) vs 168.0 (62.3-601.3), P <.001]. At multivariate logistic regression analysis, independent predictors associated with higher risk of poor myocardial reperfusion (STR <70%) were: NT-proBNP (OR 1.17, 95%CI 1.04-1.31, P = .009), diabetes mellitus (OR 1.87, 95%CI 1.14-3.07, P = .013), anterior infarct location (OR 2.74, 95% CI 2.00-3.77, P <.001), time to intervention (OR 1.06, 95%CI 1.01-1.11, P = .021), randomisation to placebo (OR 1.45, 95%CI 1.05-1.99, P = .022). Conclusions: In STEMI patients, higher baseline NT-proBNP level was independently associate with higher risk of poor myocardial reperfusion, supporting the potential use of NT-proBNP as an early marker for risk stratification of myocardial reperfusion after pPCI in STEMI patients
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