Deeltaak- versus hele-taakinstructie:Een onderzoek in het Praktijkonderwijs

Al heel lang probeert men leerlingen vaardigheden aan te leren door de vaardigheden op te splitsen in deelvaardigheden en deze achtereenvolgens te oefenen. Voor het uitvoeren van de eindvaardigheid moeten de deelvaardigheden worden samengevoegd door de lerende. Dat kan vooral problemen opleveren bij de lerende wanneer de eindtaak complex is. Daarentegen oriënteren recente instructietheorieën zich op complexe taken. Deze taken worden in tegenstelling tot die in de “traditionele” instructietheorie vanaf het begin in zijn geheel aangeboden. Dit zou tot betere toepassing van de vaardigheid in nieuwe situaties leiden (Van Merrienboer, 1997). De vraag is of een van deze twee benaderingen effectiever is voor leerlingen in het Praktijkonderwijs. Dit onderzoek spitst zich toe op het leren koken met als eindtaak het leren klaarmaken van een recept. In de hele-taakbenadering wordt vanaf het begin de vaardigheid van het uitvoeren van het kookrecept in zijn geheel aangeboden. In de deeltaakbenadering worden de technieken voor het klaar maken van een recept één voor één aangeleerd. Aan het eind kregen de leerlingen van beide instructiebenaderingen dezelfde toets: het zelfstandig uitvoeren van een nieuw recept. Het onderzoek is uitgevoerd bij leerlingen uit drie leerjaren van het Praktijkonderwijs. Klassen leerlingen werden binnen een leerjaar willekeurig toegewezen aan twee condities: een deeltaakconditie en een hele-taakconditie. Voor beide condities is een lessenserie ontworpen voor dezelfde eindtaken. Na de lessenserie werden de leerlingen getoetst met praktijktoetsen. Uit de resultaten blijkt dat in leerjaar 1 en 3 een significant verschil bestaat tussen de condities in het zelfstandig klaar maken van een onbekend recept. De leerlingen in de deeltaakconditie presteerden beter dan de leerlingen in de hele-taakconditie. In leerjaar 2 is er geen verschil. Het onderzoek geeft aanleiding te veronderstellen dat leerlingen in het Praktijkonderwijs meer baat hebben bij een deeltaakbenadering waarin voorafgaande taken worden herhaald in de daaropvolgende taken. In de discussie wordt verder op deze veronderstelling ingegaan en worden punten besproken waarop de huidige instructieaanpak van de Praktijkschool kan worden verbeterd

Psychosocial correlates of eating behavior in children and adolescents: a review

<p>Abstract</p> <p>Background</p> <p>Understanding the correlates of dietary intake is necessary in order to effectively promote healthy dietary behavior among children and adolescents. A literature review was conducted on the correlates of the following categories of dietary intake in children and adolescents: Fruit, Juice and Vegetable Consumption, Fat in Diet, Total Energy Intake, Sugar Snacking, Sweetened Beverage Consumption, Dietary Fiber, Other Healthy Dietary Consumption, and Other Less Healthy Dietary Consumption in children and adolescents.</p> <p>Methods</p> <p>Cross-sectional and prospective studies were identified from PubMed, PsycINFO and PsycArticles by using a combination of search terms. Quantitative research examining determinants of dietary intake among children and adolescents aged 3–18 years were included. The selection and review process yielded information on country, study design, population, instrument used for measuring intake, and quality of research study.</p> <p>Results</p> <p>Seventy-seven articles were included. Many potential correlates have been studied among children and adolescents. However, for many hypothesized correlates substantial evidence is lacking due to a dearth of research. The correlates best supported by the literature are: perceived modeling, dietary intentions, norms, liking and preferences. Perceived modeling and dietary intentions have the most consistent and positive associations with eating behavior. Norms, liking, and preferences were also consistently and positively related to eating behavior in children and adolescents. Availability, knowledge, outcome expectations, self-efficacy and social support did not show consistent relationships across dietary outcomes.</p> <p>Conclusion</p> <p>This review examined the correlates of various dietary intake; Fruit, Juice and Vegetable Consumption, Fat in Diet, Total Energy Intake, Sugar Snacking, Sweetened Beverage Consumption, Dietary Fiber, Other Healthy Dietary Consumption, and Other Less Healthy Dietary Consumption in cross-sectional and prospective studies for children and adolescents. The correlates most consistently supported by evidence were perceived modeling, dietary intentions, norms, liking and preferences. More prospective studies on the psychosocial determinants of eating behavior using broader theoretical perspectives should be examined in future research.</p

Inkomensvergelijking vezelgewassen versus graan

In 2012 is de verwerkingssteun voor o.a. vezelvlas en vezelhennep volledig ontkoppeld. Dat betekent dat deze steun wordt omgezet in een vaste inkomenstoeslag voor de teler, die daarvoor niet langer verplicht is om vlas of vezelhennep te telen. Daardoor dreigt de teelt van vlas en vezelhennep het af te leggen tegen financieel aantrekkelijkere teelten. In dit onderzoek worden de financiële aspecten voor agrarische ondernemers berekend, om het ministerie van EL&I te informeren bij beleidsvorming. Omdat de beide teelten regionaal geconcentreerd zijn, wordt de vergelijking gemaakt voor vlasteelt in Zuidwest Nederland en voor vezelhennep voor het Noordoostelijk zand- en dalgebied

Veiligheid en beveiliging van offshore Windturbineparken Integrale veiligheidsstudie

Dit rapport geeft de bevindingen weer van een integrale studie naar de veiligheidsaspecten rond de realisatie van (meerdere) offshore windturbineparken op het Nederlandse deel van de Noordzee. Het onderzoek is geïnitieerd in het kader van het onderzoeksprogramma We@Sea. Offshore windturbineparken beïnvloeden de veiligheid op zee b.v. doordat ze ruimte innemen die voorheen vrij gebruikt konden worden door scheepvaart en visserij. Door verdringing treedt verdichting op van het scheepvaartverkeer rondom het windturbinepark en het ingenomen gebied wordt onbereikbaar voor vissers. Daarnaast zijn de windturbines objecten waarmee schepen in aanvaring kunnen komen b.v. wanneer zij op drift raken. De gevaren in deze zijn wederzijds, zowel de windturbines kunnen schade oplopen door zo’n gebeurtenis, maar ook de schepen kunnen beschadigd raken. In het geval dat het schip een milieugevaarlijke lading b.v. chemicaliën of olie vervoert, dreigt er tevens gevaar voor het milieu

Viruses: incredible nanomachines. New advances with filamentous phages

During recent decades, bacteriophages have been at the cutting edge of new developments in molecular biology, biophysics, and, more recently, bionanotechnology. In particular filamentous viruses, for example bacteriophage M13, have a virion architecture that enables precision building of ordered and defect-free two and three-dimensional structures on a nanometre scale. This could not have been possible without detailed knowledge of coat protein structure and dynamics during the virus reproduction cycle. The results of the spectroscopic studies conducted in our group compellingly demonstrate a critical role of membrane embedment of the protein both during infectious entry of the virus into the host cell and during assembly of the new virion in the host membrane. The protein is effectively embedded in the membrane by a strong C-terminal interfacial anchor, which together with a simple tilt mechanism and a subtle structural adjustment of the extreme end of its N terminus provides favourable thermodynamical association of the protein in the lipid bilayer. This basic physicochemical rule cannot be violated and any new bionanotechnology that will emerge from bacteriophage M13 should take this into account

5-Formylcytosine alters the structure of the DNA double helix.

The modified base 5-formylcytosine (5fC) was recently identified in mammalian DNA and might be considered to be the 'seventh' base of the genome. This nucleotide has been implicated in active demethylation mediated by the base excision repair enzyme thymine DNA glycosylase. Genomics and proteomics studies have suggested an additional role for 5fC in transcription regulation through chromatin remodeling. Here we propose that 5fC might affect these processes through its effect on DNA conformation. Biophysical and structural analysis revealed that 5fC alters the structure of the DNA double helix and leads to a conformation unique among known DNA structures including those comprising other cytosine modifications. The 1.4-Å-resolution X-ray crystal structure of a DNA dodecamer comprising three 5fCpG sites shows how 5fC changes the geometry of the grooves and base pairs associated with the modified base, leading to helical underwinding.E.-A.R. is supported as a Herchel Smith Fellow. The Balasubramanian laboratory is supported by a Senior Investigator Award from the Wellcome Trust (099232/Z/12/Z to S.B.), and it also receives core funding from Cancer Research UK (C9681/A11961 to S.B.). D.Y.C. is supported by the Crystallographic X-ray Facility (CXF) at the Department of Biochemistry, University of Cambridge, and B.F.L. is supported by the Wellcome Trust (076846/Z/05/A to B.F.L.). We thank the staff of Soleil and Diamond Light Source for use of facilities. We thank C. Calladine for stimulating discussions.This is the accepted manuscript for a paper published in Nature Structural & Molecular Biology 22, 44–49 (2015) doi: 10.1038/nsmb.293

Role of germline aberrations affecting CTNNA1, MAP3K6 and MYD88 in gastric cancer susceptibility

Background In approximately 10% of all gastric cancer (GC) cases, a heritable cause is suspected. A subset of these cases have a causative germline CDH1 mutation; however, in most cases the cause remains unknown. Our objective was to assess to what extent these remaining cases may be explained by germline mutations in the novel candidate GC predisposing genes CTNNA1, MAP3K6 or MYD88. Methods We sequenced a large cohort of unexplained young and/or familial patients with GC (n=286) without a CDH1germline mutation for germline variants affecting CTNNA1, MAP3K6 and MYD88 using a targeted next-generation sequencing approach based on single-molecule molecular inversion probes. Results Predicted deleterious germline variants were not encountered in MYD88, but recurrently observed in CTNNA1 (n=2) and MAP3K6 (n=3) in our cohort of patients with GC. In contrast to deleterious variants in CTNNA1, deleterious variants in MAP3K6 also occur frequently in the general population. Conclusions Based on our results MAP3K6 should no longer be considered a GC predisposition gene, whereas deleterious CTNNA1 variants are confirmed as an infrequent cause of GC susceptibility. Biallelic MYD88 germline mutations are at most a very rare cause of GC susceptibility as no additional cases were identified.This study was funded by KWF Kankerbestrijding (grant number KUN2013-5876, RSvdP)

Improving interinstitutional and intertechnology consistency of pulmonary SBRT by dose prescription to the mean internal target volume dose.

Dose, fractionation, normalization and the dose profile inside the target volume vary substantially in pulmonary stereotactic body radiotherapy (SBRT) between different institutions and SBRT technologies. Published planning studies have shown large variations of the mean dose in planning target volume (PTV) and gross tumor volume (GTV) or internal target volume (ITV) when dose prescription is performed to the PTV covering isodose. This planning study investigated whether dose prescription to the mean dose of the ITV improves consistency in pulmonary SBRT dose distributions. This was a multi-institutional planning study by the German Society of Radiation Oncology (DEGRO) working group Radiosurgery and Stereotactic Radiotherapy. CT images and structures of ITV, PTV and all relevant organs at risk (OAR) for two patients with early stage non-small cell lung cancer (NSCLC) were distributed to all participating institutions. Each institute created a treatment plan with the technique commonly used in the institute for lung SBRT. The specified dose fractionation was 3 × 21.5 Gy normalized to the mean ITV dose. Additional dose objectives for target volumes and OAR were provided. In all, 52 plans from 25 institutions were included in this analysis: 8 robotic radiosurgery (RRS), 34 intensity-modulated (MOD), and 10 3D-conformal (3D) radiation therapy plans. The distribution of the mean dose in the PTV did not differ significantly between the two patients (median 56.9 Gy vs 56.6 Gy). There was only a small difference between the techniques, with RRS having the lowest mean PTV dose with a median of 55.9 Gy followed by MOD plans with 56.7 Gy and 3D plans with 57.4 Gy having the highest. For the different organs at risk no significant difference between the techniques could be found. This planning study pointed out that multiparameter dose prescription including normalization on the mean ITV dose in combination with detailed objectives for the PTV and ITV achieve consistent dose distributions for peripheral lung tumors in combination with an ITV concept between different delivery techniques and across institutions