Beheer van duinbossen : verslag veldwerkplaats - duin en kust, PWN Waterleidingbedrijf Noord-Holland, Castricum, 4 juni 2010

De variatie in bostypen wordt in het jonge duinlandschap vooral bepaald door twee belangrijke factoren: water en kalk, zo vertelt Patrick Hommel (Alterra). Natte bossen die permanent onder invloed staan van het grondwater (broekbossen) zijn altijd erg zeldzaam geweest in de duinstreek. Vochtige bossen die in het winterhalfjaar regelmatig onder water lopen, waren vroeger - vooral in het middenduin - veel algemener. Het waren lage bossen (of hoge struwelen!) met veel zachte berk in de boomlaag en een zeer soortenrijke kruidlaag met veelal een hoog aandeel van watermunt. Door verdroging en de daarop volgende verzuring zijn deze bossen sterk van karakter veranderd en de oorspronkelijke soortenrijkdom krijg je waarschijnlijk ook niet meer teru

Sharing tasks or sharing actions? Evidence from the joint Simon task.

In a joint Simon task, a pair of co-acting individuals divide labors of performing a choice-reaction task in such a way that each actor responds to one type of stimuli and ignores the other type that is assigned to the co-actor. It has been suggested that the actors share the mental representation of the joint task and perform the co-actor’s trials as if they were their own. However, it remains unclear exactly which aspects of co-actor’s task-set the actors share in the joint Simon task. The present study addressed this issue by manipulating the proportions of compatible and incompatible trials for one actor (inducer actor) and observing its influences on the performance of the other actor (diagnostic actor) for whom there were always an equal proportion of compatible and incompatible trials. The design of the present study disentangled the effect of trial proportion from the confounding effect of compatibility on the preceding trial. The results showed that the trial proportions for the inducer actor had strong influences on the inducer actor’s own performance, but it had little influence on the diagnostic actor’s performance. Thus, the diagnostic actor did not represent aspects of the inducer actor’s task-set beyond stimuli and responses of the inducer actor. We propose a new account of the effect of preceding compatibility on the joint Simon effect.Action Contro

De linde terug in het bos : verslag veldwerkplaats Droog zandlandschap Doorwerth, 9 mei 2008

Verslag van de veldwerkdag Droog zandlandschap in Doorwerth op 9 mei 2008. Tijdens deze veldwerkdag is in de bossen bij kasteel Doorwerth gekeken naar de 0strooisellaag van verschillende bostypen. Aanplant van lindes in een eikenbeukenbos op een relatief arme bodem geeft een zichtbare verbetering van de strooisellaag. De verzuring die in bossen plaatsvindt kan op deze manier plaatselijk worden bestreden. De aanplant van linde en andere boomsoorten met goed verterend strooisel kan dus een bijdrage leveren aan het oplossen van het verzuringsprobleem. Daarbij leidt de verbeterde strooiselkwaliteit tot een verhoging van biodiversiteit en bloemenpracht in het voorjaar

Band gap bowing of binary alloys: Experimental results compared to theoretical tight-binding supercell calculations for CdZnSe

Compound semiconductor alloys of the type ABC find widespread applications as their electronic bulk band gap varies continuously with x, and therefore a tayloring of the energy gap is possible by variation of the concentration. We model the electronic properties of such semiconductor alloys by a multiband tight-binding model on a finite ensemble of supercells and determine the band gap of the alloy. This treatment allows for an intrinsic reproduction of band bowing effects as a function of the concentration x and is exact in the alloy-induced disorder. In the present paper, we concentrate on bulk CdZnSe as a well-defined model system and give a careful analysis on the proper choice of the basis set and supercell size, as well as on the necessary number of realizations. The results are compared to experimental results obtained from ellipsometric measurements of CdZnSe layers prepared by molecular beam epitaxy (MBE) and photoluminescence (PL) measurements on catalytically grown CdZnSe nanowires reported in the literature.Comment: 7 pages, 6 figure

The emergence of risk-based regulation in higher education:Relevance for entrepreneurial risk taking by business schools

PurposeBusiness schools are increasingly positioning themselves as entrepreneurial risk‐takers. In doing so, they are front‐runners of a marketization trend affecting the entire higher education sector. In response, governments have begun to subject higher education sectors to systems of risk‐based regulation. The purpose of this paper is to study the likely impact of regulatory change on business school behaviour.Design/methodology/approachThe article focuses on the financial dimension of institutional performance and draws on the corporate risk management literature to derive general design principles for managing risk‐taking in business schools. These are matched with a review of the regulation literature to evaluate regulatory effectiveness.FindingsBusiness schools are facing a double‐hurdle test when managing their risk position. They need to protect their financial solvency with the maintenance of properly functioning risk management systems. At the same time, they will increasingly be subjected to regulatory scrutiny with regulatory shortcomings likely to be mapped into binding but sub‐optimal behavioural constraints. The article offers initial reflections as to how business schools can cope with this double‐hurdle.Originality/valueRisk management in higher education, here with a specific reference to business schools, has so far been under‐theorized from a financial perspective and, as a consequence, the debate on risk‐based regulation lacks a proper foundation. The article addresses this shortcoming.</jats:sec

Defect distribution in a-plane GaN on Al2O3

The authors studied the structural and point defect distributions of hydride vapor phase epitaxial GaN film grown in the [11−20] a direction on (1−102) r-plane sapphire with metal-organic vapor phase deposited a-GaN template using transmission electron microscopy, secondary ion mass spectrometry, and positron annihilation spectroscopy. Grown-in extended and point defects show constant behavior as a function of thickness, contrary to the strong nonuniform defect distribution observed in GaN grown along the [0001] direction. The observed differences are explained by orientation-dependent and kinetics related defect incorporation.Peer reviewe

"Unfocus" on foc.us: Commercial tDCS headset impairs working memory

In this study, we tested whether the commercial transcranial direct current stimulation (tDCS) headset foc.us improves cognitive performance, as advertised in the media. A single-blind, sham-controlled, within-subject design was used to assess the effect of online and off-line foc.us tDCS—applied over the prefrontal cortex in healthy young volunteers (n = 24) on working memory (WM) updating and monitoring. WM updating and monitoring, as assessed by means of the N-back task, is a cognitive-control process that has been shown to benefit from interventions with CE-certified tDCS devices. For both online and off-line stimulation protocols, results showed that active stimulation with foc.us, compared to sham stimulation, significantly decreased accuracy performance in a well-established task tapping WM updating and monitoring. These results provide evidence for the important role of the scientific community in validating and testing far-reaching claims made by the brain training industry