Numerical Results for the System Noise Temperature of an Aperture Array Tile and Comparison with Measurements

The purpose of this report is to document the noise performance of a complex beamforming array antenna system and to characterize the recently developed noise measurement facility called THACO, which was developed at ASTRON. The receiver system includes the array antenna of strongly coupled 144 TSA elements, 144 Low Noise Amplifiers (LNAs) (Tmin =35-40K) and the data recording/storing facilities of the initial test station that allow for off-line digital beamforming. The primary goal of this study is to compare the measured receiver noise temperatures with the simulated values for several practical beamformers, and to predict the associated receiver noise coupling contribution, antenna thermal noise and ground noise pick-up (due to the back radiation).Comment: ASTRON repor

Learning during visual search in children with attentional and learning problems: a trial to trial evaluation of RT and ERP measures.

Trial to trial Event Related Potentials (ERPs) were recorded from children with attentional problems (APs), learning problems (LPs), and from children without these problems (NCs). The task required the subjects to memorize two figures and to selectively respond to their occurrence in a series of stimuli. Stimuli consisted of a display of figures at eight locations in a circle, whereby the targets were presented at a random or a fixed location. Learning from knowledge of prior displays was possible only in the fixed condition. Learning during presentation of the fixed series was manifest in several components. A Slow Wave (SW) difference between series, initially not present, developed within seven trials, and thus corresponded to the rapidity with which the reaction times (RTs) decreased over trials. A larger occipital SW difference was discovered in AP children and a larger frontocentral one in LP children compared to normals. The latency of this SW and the P300 difference between series were delayed with about 200 msec in APs compared to NCs. The task difference in the earliest component, the P120, that increased after behavioral task acquisition was completed, was seen in normal children only. This probably reflected feature-specific (location) attentional demands, that decreased slowly in normal children when the task became more predictable following a number of trials. Task differences of the N200, possibly reflecting covert orienting of attention, were initially smaller in APs and LPs than those of NCs, but they increased in APs (and in LPs more slowly) over trials. Differences were found for parietal amplitudes of the P300 in LPs and NCs, but not for APs. We concluded that AP children show early deficits that could originate from a limited capacity in focussing attention, which in turn prolongs stimulus evaluation. All subsequent processes are delayed by a similar amount of time. In addition, the relatively small frontocentral ERP's of the AP group suggest diminished frontal functioning. Problems in task acquisition and a prolonged process of memory updating might be induced by the slow adaptation to task differences in LP's, and delayed parietal SWs during task acquisition together with a marked frontocentral distribution and no RT difference

The different faces of (high) sensitivity, toward a more comprehensive measurement instrument: development and validation of the sensory processing sensitivity questionnaire (SPSQ).

Health and self-regulatio

Boetseren met water

Dit boekje is uitgebracht in het kader van het onderzoeksprogramma 'regionale identiteit en natuur en landschapsontwikkeling' van LNV. Binnen dit programma richt Alterra zich op het ontwikkelen van kennis voor beleid en beheer, waarmee de kwaliteit van natuur en landschap kan worden verstrekt. Op verhalende wijze brengt deze publicatie onder de aandacht, dat bij de uitvoering van projecten de succesfactoren niet altijd bepaald wordt door het project zel

Nieuwe grondhouding in ruimtelijk beleid

Op basis van een analyse van de veranderende ruimtelijke praktijk aan de hand van de ideeën van Williamson schetsen de auteurs van dit artikel twee handelingsperspectieven waarmee een nieuwe vorm van ruimtelijk beleid vorm kan krijgen. Twee handelingsperspectieven waarbij niet alleen het institutionele landschap, maar ook de planningscultuur en governance capaciteiten van ruimtelijke planners in beschouwing worden genomen. Het gaat om strategisch navigeren en lerend organiseren

De Wet verplichte meldcode geëvalueerd:de eerste stappen gezet, maar doel nog niet bereikt

De conclusie van het eerste evaluatieonderzoek van de Wet verplichte meldcode is dat met de invoering van een meldcode de eerste stappen zijn gezet richting een ondersteuningsmodel voor professionals om signalen van huiselijk geweld en kindermishandeling te herkennen en hen handvatten te bieden om sneller en adequater hulp te bieden