On the origin of the difference between the runaway velocities of the OB-supergiant X-ray Binaries and the Be/X-ray Binaries

The recent finding by Chevalier & Ilovaisky (1998) that OB-supergiant X-ray binaries have relatively large runaway velocities whereas Be/X-ray binaries have low runaway velocities, provides confirmation of the current models for the formation of these two types of systems. These predict a difference in runaway velocity of an order of magnitude. This difference basically results from the variation of the fractional helium core mass as a function of stellar mass, in combination with the conservation of orbital angular momentum during the mass transfer phase that preceded the formation of the compact object in the system. This combination results into: (i) Systematically narrower pre-supernova orbits in the OB-supergiant systems than in the Be-systems, and (ii) A larger fractional amount of mass ejected in the supernovae in high-mass systems relative to systems of lower mass. Regardless of possible kick velocities imparted to neutron stars at birth, this combination leads to a considerable difference in average runaway velocity between these two groups. The observed low runaway velocities of the Be/X-ray binaries confirm that in most cases not more than 1 to 2Msun was ejected in the supernovae that produced their neutron stars. This, in combination with the --on average-- large orbital eccentricities of these systems, indicates that their neutron stars must have received a velocity kick in the range 60 - 250 km/s at birth.Comment: reduced abstract, 13 pages, accepted by A&

Social support shopping: Evidence from a regression discontinuity in disability insurance reform

This paper examines how a change in the generosity of one social assistance program generates spillovers onto other social assistance programs. We exploit an age discontinuity in the stringency of the 1993 Dutch disability reforms to estimate the causal effect of exit from disability insurance (DI) on participation in other social assistance programs. We find strong evidence of social support shopping: 43 percent of those induced to leave DI due to the reform receive an alternative form of social assistance two years after the implementation of the reform. As a result, for each Euro saved in DI benefits, the government has to spend an extra 60 cents in other social assistance programs. This crowd-out rate grows from 60% to 69% if we also take into account the response of the partners' of those affected by the DI reform. The crowd-out effect declines over time, but is still 25% eight years after the reform

A good beginning:study protocol for a group-randomized trial to investigate the effects of sit-to-stand desks on academic performance and sedentary time in primary education

Background Sedentary behavior is associated with health risks and academic under-achievement in children. Still, children spend a large part of their waking hours sitting at a desk at school. Recent short-term studies demonstrated the potential of sit-to-stand desks to reduce sitting time in primary education. The program of "A Good Beginning" was conceived to assess the long-term effects of sit-to-stand desks on sitting time in primary education, and to examine how sit-to-stand desks versus regular desks relate to academic performance, and measures of executive functioning, health and wellbeing. The present paper describes the design of this group-randomized trial, which started in 2017 and will be completed in 2019. Methods Children of two grade-three groups (age 8-9) following regular primary education in Leiden, The Netherlands, were recruited. A coin toss determined which group is the experimental group; the other group is the control group. All children in the experimental group received sit-to-stand desks. They are invited and motivated to reduce sedentary time at school, however, it is their own choice to sit or stand. Children in the control group use regular desks. Otherwise, both groups receive regular treatment. Outcomes are assessed at baseline (T0) and at five follow-up sessions (T1-T5) alternately in winter and summer seasons over three academic years. Primary outcome measures are academic performance, and the proportion of sitting time at school, measured with a 3D accelerometer. Secondary outcome measures are a number of measures related to executive functioning (e.g., N-back task for working memory), health (e.g., height and weight for BMI), and wellbeing (e.g., KIDSCREEN-52 for Quality of Life). Discussion A Good Beginning is a two-and-a-half-year research program, which aims to provide a better understanding of the long-term effects of sit-to-stand desks on sedentary time at school and the relation between sitting time reduction and academic performance, executive functioning, health and wellbeing. The findings may serve as useful information for policy making and practical decision making for school and classroom environments

Next-generation metrics: responsible metrics and evaluation for open science

This is the final report of the European Commission's Expert Group on Altmetrics, which undertook its work over the course of 2016. The report outlines a framework for next-generation metrics in the context of the EC's Open Science agenda and includes a series of recommendations for how responsible metrics can be built into the design and evaluation of the EU's Ninth Framework Programme (FP9)

Selective citation in the literature on the hygiene hypothesis:A citation analysis on the association between infections and rhinitis

Objective Our objective was to assess the occurrence and determinants of selective citation in scientific publications on Strachan's original hygiene hypothesis. His hypothesis states that lack of exposure to infections in early childhood increases the risk of rhinitis. Setting Web of Science Core Collection. Participants We identified 110 publications in this network, consisting of 5551 potential citations. Primary and secondary outcome measures Whether a citation occurs or not, measured and analysed according to the preregistered protocol. Results We found evidence for citation bias in this field: publications supportive of the hypothesis were cited more often than non-supportive publications (OR adjusted for study design [adjOR] 2.2, 95% CI 1.6 to 3.1), and the same was the case for publications with mixed findings (adjOR 3.1, 95% CI 2.2 to 4.5). Other relevant determinants for citation were type of exposure, specificity, journal impact factor, authority and self-citation. Surprisingly, prospective cohort studies were cited less often than other empirical studies. Conclusions There is clear evidence for selective citation in this research field, and particularly for citation bias

Community policing in the Netherlands: A continuously changing constant

__Abstract__ 1977 was an important year for the Dutch police as it was then that a seminal strategy document called ‘A Changing Police was published that would set the course for the next three decades. The writers of the report felt that for the police to bridge the growing gap between them and the society they serve, they would have to be innovative, and think outside of their usual security paradigms. They found their solution in community policing and the strategy document laid out the framework for Community Policing (COP) in the Netherlands. This document was widely considered a milestone in the development of Dutch policing (see Cachet et al. 1998). However, by 2005, the Dutch Board of Chief Commissioners felt it necessary to publish a new strategy document to once again map out the future of Dutch Policing. After nearly three decades, the Dutch police was again in need of a shared philosophy that would serve as a foundation for their mandate. This new document was titled ‘The Police in Evolution’ (PIE) but it stayed true to the values of COP by once again focusing on the local community and stressing community policing. In this paper we explore the establishment and development of Dutch COP. We look at several distinct phases in the long term development of Dutch COP, and examine the factors that explain the shifts that have taken place in the way Dutch COP is carried out. We ask also about the prospects of Dutch COP in the future. The paper will consist of four sections. In the first Section, we examine the historical roots and the development of Dutch COP since its inception in 1977. In Section 2, we look at the current state of affairs for COP in the Netherlands. In the third section, we put forward several explanations for the significant shifts that have taken place over the course of the COP’s 30-year history. In the fourth section, we discuss the prospects for Dutch COP in the coming years. Section 5 presents our conclusions