Wie of wat gelooft u? De status van kennis in de sociale media

De opkomst en daarmee het belang van sociale media kan niet als iets ‘nieuws’ beschouwd worden. Zeker als we ‘nieuw’ definiëren in termen van gisteren, vandaag of morgen. Sociale media zijn sinds de jaren 2000 een steeds groter en populairder platform geworden. Ook het openbaar bestuur probeert de laatste jaren aan te haken bij deze ontwikkeling en vooral de mogelijkheden van sociale media te benutten. Een betrekkelijk nieuw en belangrijk vraagstuk als gevolg van deze activiteiten op sociale media wordt nog wel eens vergeten en onderschat

Top transport in electroweak baryogenesis

In non-supersymmetric models of electroweak baryogenesis the top quark plays a crucial role. Its CP-violating source term can be calculated in the WKB approximation. We point out how to resolve certain discrepancies between computations starting from the Dirac equation and the Schwinger--Keldysh formalism. We also improve on the transport equations, keeping the W-scatterings at finite rate. We apply these results to a model with one Higgs doublet, augmented by dimension-6 operators, where our refinements lead to an increase in the baryon asymmetry by a factor of up to about 5.Comment: 17 pages, 3 figures, references adde

‘Trust the experts!’ Risk definitions in Dutch online forums about the ‘swine flu’

Citizens are becoming increasingly likely to challenge the knowledge bases underlying policy programmes that deal with risks. This paper investigates how participants in online discussions engage in interactions between expert knowledge, ‘commons knowledge’ and policy assumptions. The concept of ‘boundary objects’, arrangements that allow different groups to work together without consensus, is used to analyse the role of online discussions in these interactions. Discussions on three Dutch online forums about the swine flu are investigated according to a framework for policy argumentation. Interaction between knowledge domains was limited, and it varied in focus and nature across the three forums. Each discussion functioned as a partial approximation of a boundary object. Government organizations should be more aware of the variety of online forums in which discussions about societal risks take place. Several practical options are presented for policy-making with regard to risks

The 'Publicness-puzzle' in public leadership. A theoretical exploration of leadership in public organizations

Abstract Following a contingency approach we argue that the content and style of administrative leadership depends on characteristics of the public context. The purpose of the paper is to develop hypotheses on the relationships between several dimensions of publicness and the content and style of leadership, by reviewing academic literature on public leadership. To build our argument we first conceptualize leadership and distinguish several theories, definitions, and styles of leadership based on four different basic conceptions of what leadership is: Leadership as traits; 2. Leadership as behavior; 3. Leadership as managing of meaning; 4. Leadership as interaction processes. Then, Bozeman’s model of publicness is described as well as the effects of publicness on organizational environments, organizational goals, organizational structures and managerial values. As a final step we develop hypotheses that relate leadership to publicness and identify possible contradictory demands administrative leadership has to deal with. We conclude by outlining a research agenda on administrative leadership

Hoe beoordelen topambtenaren veranderingen? De bijzondere positie van de Nederlandse topambtenaar

Dit artikel toont hoe topambtenaren in tien Europese landen veranderingen in de publieke sector beoordelen op een aantal dimensies, zoals kwaliteit, kostenefficiëntie, ethiek, effectiviteit en de aantrekkelijkheid van de publieke sector als werkgever. Nederlandse topambtenaren worden vergeleken met collega’s van negen andere Europese landen. Het onderzoek is gebaseerd op de grootschalige academische COCOPS Top Executive Survey. Voor dit artikel wordt gewerkt met een subsample van 3173 leidende ambtenaren. Resultaten tonen dat topambtenaren in Nederland positief zijn over veranderingen in de kostenefficiëntie en kwaliteit van de dienstverlening, maar zich zorgen maken over de aantrekkelijkheid van de overheid als werkgever en het vertrouwen van burgers in de overheid. Tegelijk zijn Nederlandse topambtenaren het meest positief over veranderingen in de werking van de publieke sector van alle ondervraagde topambtenaren. Enkel voor wat betreft de aantrekkelijkheid van de publieke sector als werkgever scoort Nederland eerder slecht in de Europese vergelijkin

Cosmological Constant, Gauge Hierarchy and Warped Geometry

It is suggested that the mechanism responsible for the resolution of the gauge hierarchy problem within the warped geometry framework can be generalized to provide a new explanation of the extremely tiny vacuum energy density rho_V suggested by recent observations. We illustrate the mechanism with some 5D examples in which the true vacuum energy is assumed to vanish, and rho_V is associated with a false vacuum energy such that rho_V^{1/4} ~ TeV^2/M_{Pl} ~ 10^{-3} eV, where M_{Pl} denotes the reduced Planck mass. We also consider a quintessence-like solution to the dark energy problem.Comment: 10 pages, LaTeX, 2 figures, section on quantum corrections added, version to appear in Phys. Rev.

Evaluation of non-chemical seed treatment methods for the control of Alternaria dauci and A. radicina on carrot seeds

The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Control of both Alternaria species by seed treatment with the resistance inducers was generally poor. Results were also not satisfactory with most of the formulated commercial micro-organism preparations. Based on the average of five field trials, one of these, BA 2552 (Pseudomonas chlororaphis), provided a low but significant increase in plant stand. Among the experimental micro-organisms, the best results were obtained with Pseudomonas sp. strain MF 416 and Clonostachys rosea strain IK726. A similar level of efficacy was provided by seed treatment with an emulsion (1%) of thyme oil in water. Good and consistent control was generally achieved with the physical methods aerated steam, hot water and electron treatment. Aerated steam treatment was, apart from the thiram-containing chemical standard, the best single treatment, and its performance may at least partially be due to extensive pre-testing, resulting in dosages optimally adapted to the respective seed lot. In some of the experiments the effect of the hot water treatment, which was tested at a fixed, not specifically adapted dosage, was significantly improved when combined with a Pseudomonas sp. MF 416 or C. rosea IK726 treatment. The results are discussed in relation to the outcome of experiments in which the same seed treatment methods and agents were tested in other seed-borne vegetable pathosystems

The association between patellar tendon stiffness measured with shear-wave elastography and patellar tendinopathy

Objectives: (1) To determine the association between patellar tendon stiffness and the presence of patellar tendinopathy (PT). (2) To evaluate the reliability of shear-wave elastography (SWE). Methods: Participants were consecutively enrolled between January 2017 and June 2019. PT was diagnosed clinically and confirmed by either grayscale US or power Doppler US, or both. Controls had no history of anterior knee pain and no clinical signs of PT. Patellar tendon stiffness (kilopascal, kPa) was assessed using SWE. Logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Reliability analyses included coefficients-of-variation (CV), coefficients-of-repeatability (CR), intraclass correlation coefficient (ICC) for intraobserver and interobserver reliability, and Bland-Altman analysis. Results: In total, 76 participants with PT (58 men, mean age 24.4 ± 3.8 years) and 35 asymptomatic controls (16 men, mean age 21.5 ± 3.8 years) were included. Univariate analyses (OR 1.094, 95% CI 1.061–1.128, p <.001) and adjusted multivariate analyses (OR 1.294, 95% CI 1.044–1.605, p =.018) showed that athletes with PT had significantly increased patellar tendon stiffness. ICC for intraobserver reliability was 0.95 (95% CI 0.92–0.97), CR (CV) 12 kPa (10%) and 0.79 (95% CI 0.65–0.88), CR (CV) 18 kPa (21%) for interobserver reliability. Mean differences from Bland-Altman analysis were 5.6 kPa (95% CI 3.1–8.1, p <.001) for intraobserver reliability and 4.6 kPa (95% CI 1.9–7.2, p <.001) for interobserver reli

Interregional compensatory mechanisms of motor functioning in progressing preclinical neurodegeneration.

Understanding brain reserve in preclinical stages of neurodegenerative disorders allows determination of which brain regions contribute to normal functioning despite accelerated neuronal loss. Besides the recruitment of additional regions, a reorganisation and shift of relevance between normally engaged regions are a suggested key mechanism. Thus, network analysis methods seem critical for investigation of changes in directed causal interactions between such candidate brain regions. To identify core compensatory regions, fifteen preclinical patients carrying the genetic mutation leading to Huntington's disease and twelve controls underwent fMRI scanning. They accomplished an auditory paced finger sequence tapping task, which challenged cognitive as well as executive aspects of motor functioning by varying speed and complexity of movements. To investigate causal interactions among brain regions a single Dynamic Causal Model (DCM) was constructed and fitted to the data from each subject. The DCM parameters were analysed using statistical methods to assess group differences in connectivity, and the relationship between connectivity patterns and predicted years to clinical onset was assessed in gene carriers. In preclinical patients, we found indications for neural reserve mechanisms predominantly driven by bilateral dorsal premotor cortex, which increasingly activated superior parietal cortices the closer individuals were to estimated clinical onset. This compensatory mechanism was restricted to complex movements characterised by high cognitive demand. Additionally, we identified task-induced connectivity changes in both groups of subjects towards pre- and caudal supplementary motor areas, which were linked to either faster or more complex task conditions. Interestingly, coupling of dorsal premotor cortex and supplementary motor area was more negative in controls compared to gene mutation carriers. Furthermore, changes in the connectivity pattern of gene carriers allowed prediction of the years to estimated disease onset in individuals. Our study characterises the connectivity pattern of core cortical regions maintaining motor function in relation to varying task demand. We identified connections of bilateral dorsal premotor cortex as critical for compensation as well as task-dependent recruitment of pre- and caudal supplementary motor area. The latter finding nicely mirrors a previously published general linear model-based analysis of the same data. Such knowledge about disease specific inter-regional effective connectivity may help identify foci for interventions based on transcranial magnetic stimulation designed to stimulate functioning and also to predict their impact on other regions in motor-associated networks

Detectable gravitational waves from very strong phase transitions in the general NMSSM

We study the general NMSSM with an emphasis on the parameter regions with a very strong first-order electroweak phase transition (EWPT). In the presence of heavy fields coupled to the Higgs sector, the analysis can be problematic due to the existence of sizable radiative corrections. In this paper we propose a subtraction scheme that helps to circumvent this problem. For simplicity we focus on a parameter region that is by construction hidden from the current collider searches. The analysis proves that (at least) in the identified parameter region the EWPT can be very strong and striking gravitational wave signals can be produced. The corresponding gravitational stochastic background can potentially be detected at the planned space-based gravitational wave observatory eLISA, depending on the specific experiment design that will be approved