Schematising activities in early childhood education

The purpose of this study was to determine the importance of introducing schematising to children in early childhood and to determine whether schematising can be taught to children. This was done using a longitudinal, quantitative study with a quasi-experimental design (N = 133). In this study, the use of schematising was taught to an experimental group of children to determine if it is possible to realise significantly improved results in schematising tasks for an experimental group in comparison to a control group of children who were not taught schematising. Pupils in the experimental group demonstrated significantly better results on schematising, which cannot be explained by maturation. In our future research, we will investigate the mathematical performances of these experimental and control groups in the next grade of the primary school curriculum. © 2009 Taylor & Francis

Effecten van het leren schematiserenvan jonge leerlingen op hun latere prestaties in het reken-wiskundeonderwijs.

Dit artikel betreft een anderhalf jaar durend experimenteel onderzoek naar het leren schematiseren van jonge kinderen en de effecten hiervan op hun latere leerresultaten in het reken-wiskundeonderwijs. Leerlingen in de experimentele groep participeerden in een programma waarin het schematiseren expliciet werd onderwezen en begeleid. In de controlegroep werd geen specifieke aandacht besteed aan het schematiseren. De vraagstelling was: Wat zijn de effecten van een experimentele interventie gericht op het leren schematiseren van jonge kinderen (groep 2 basisschool) op hun latere leerresultaten bij rekenwiskunde (groep 3)? Er werden vijf toetsen afgenomen om de wiskundige ontwikkeling in kaart te brengen. Na de interventieperiode werd aan de hand van een speciaal ontwikkelde toets vastgesteld of het mogelijk is om leerlingen op deze jonge leeftijd te leren schematiseren. Vervolgens is een analyse uitgevoerd naar de effecten van het programma op de latere wiskundige prestaties van de leerlingen zoals gemeten met Cito-toetsen. Het onderzoek toont aan dat jonge kinderen kunnen leren schematiseren en dat het experimentele programma een significant positief effect heeft op hun prestaties bij rekenwiskunde. Ruim een jaar na de interventie werd een retentietoets afgenomen. Hieruit bleek echter dat op dat moment geen verschil meer kon worden aangetoond tussen de experimentele en controle leerlingen. In de discussie wordt ingegaan op deze uitkomsten en worden suggesties gedaan voor vervolgonderzoek

Dispersion γZ\gamma Z-box correction to the weak charge of the proton

We consider elastic scattering of electrons off a proton target. The parity violating (PV) asymmetry arises at leading order in $\alpha$ due to interference of $\gamma$ and $Z$ exchange. The radiative corrections to this leading mechanism were calculated in the literature and included in experimental analyses, except for $\gamma Z$ box and cross-box contributions. We present here a dispersion calculation of these corrections in forward kinematics. We demonstrate that at the GeV energies of current PV experiments, such corrections are not suppressed by the small vector weak charge of the electron, as occurs in the atomic PV. Our results suggest that the current theoretical uncertainty in the analysis of the QWEAK experiment might be substantially underestimated, and more accurate account of the dispersion corrections are needed in order to interprete the PV data.Comment: 4 pages, 3 figures, revtex

Mechanical cell-matrix feedback explains pairwise and collective endothelial cell behavior in vitro

In vitro cultures of endothelial cells are a widely used model system of the collective behavior of endothelial cells during vasculogenesis and angiogenesis. When seeded in an extracellular matrix, endothelial cells can form blood vessel-like structures, including vascular networks and sprouts. Endothelial morphogenesis depends on a large number of chemical and mechanical factors, including the compliancy of the extracellular matrix, the available growth factors, the adhesion of cells to the extracellular matrix, cell-cell signaling, etc. Although various computational models have been proposed to explain the role of each of these biochemical and biomechanical effects, the understanding of the mechanisms underlying in vitro angiogenesis is still incomplete. Most explanations focus on predicting the whole vascular network or sprout from the underlying cell behavior, and do not check if the same model also correctly captures the intermediate scale: the pairwise cell-cell interactions or single cell responses to ECM mechanics. Here we show, using a hybrid cellular Potts and finite element computational model, that a single set of biologically plausible rules describing (a) the contractile forces that endothelial cells exert on the ECM, (b) the resulting strains in the extracellular matrix, and (c) the cellular response to the strains, suffices for reproducing the behavior of individual endothelial cells and the interactions of endothelial cell pairs in compliant matrices. With the same set of rules, the model also reproduces network formation from scattered cells, and sprouting from endothelial spheroids. Combining the present mechanical model with aspects of previously proposed mechanical and chemical models may lead to a more complete understanding of in vitro angiogenesis.Comment: 25 pages, 6 figures, accepted for publication in PLoS Computational Biolog

Proteomic analysis of Glossina pallidipes salivary gland hypertrophy virus virions for immune intervention in tsetse fly colonies

Many species of tsetse flies (Diptera: Glossinidae) can be infected by a virus that causes salivary gland hypertrophy (SGH). The viruses isolated from Glossina pallidipes (GpSGHV) and Musca somestica (MdSGHV) have recently been sequenced. Tsetse flies with SGH have a reduced fecundity and fertility which cause a serious problem for mass rearing in the frame of sterile insect technique (SIT) programs to control and eradicate tsetse populations in the wild. A potential intervention strategy to mitigate viral infections in fly colonies is neutralizing of the GpSGHV infection with specific antibodies against virion proteins. Two major GpSGHV virion proteins of about 130 kDa and 50 kDa, respectively, were identified by Western analysis using polyclonal rabbit antibody raised against whole GpSHGV virions. The proteome of GpSGHV, containing the antigens responsible for the immune-response, was investigated by liquid chromatography tandem mass spectrometry (LC-MS/MS) and 61 virion proteins were identified by comparison with the genome sequence. Specific antibodies were produced in rabbits against seven candidate proteins including the ORF10 / C-terminal fragment, ORF47 and ORF96 as well as proteins involved in peroral infectivity PIF-1 (ORF102), PIF-2 (ORF53), PIF-3 (ORF76) and P74 (ORF1). Antiserum against ORF10 specifically reacted to the 130 kDa protein in a Western blot analysis and to the envelope of GpSGHV using immunogold-EM. This result suggests that immune intervention of viral infections in colonies of G. pallidipes is a realistic optio

Whole-field density measurements by digital image correlation

A novel application of Synthetic Schlieren in a laboratory set-up yields a quantitative measurement of the density field of two-dimensional, stratified or homogeneous, transparent fluids in a laboratory set-up using a single camera. This application obtains local values of the density without the need for tomographic reconstruction algorithms that require images taken from different directions through the fluid nor does the application require regularization. This is achieved by placing the camera at a large oblique angle with respect to the experimental set-up. This step is motivated by a fallacy observed when applying ray tracing in a classical configuration, in which the camera’s optical axis is perpendicular to the flat surface of a fluid container. The application is illustrated by the optical determination of static density fields of linearly and nonlinearly stratified fluids, as well as of multi-layered fluids. The application is validated by comparing with density profiles obtained from probe measurements of conductivity and temperature. Our application yields similar density and density gradient profiles as the probe while also providing a whole-field measurement without disturbing the fluid, and allowing the determination of dynamical density fields

Novelty Induces Behavioural And Glucocorticoid Responses In A Songbird Artificially Selected For Divergent Personalities

Stress physiology is thought to contribute to individual differences in behaviour. In part this reflects the fact that canonical personality measures consist of responses to challenges, including novel objects and environments. Exposure to novelty is typically assumed to induce a moderate increase in glucocorticoids (CORT), although this has rarely been tested. We tested this assumption using great tits, Parus major, selected for divergent personalities (bold-fast and shy-slow explorers), predicting that the shy birds would exhibit higher CORT following exposure to a novel object. We also scored behavioural responses to the novel object, predicting that bold birds would more frequently approach the novel object and exhibit more abnormal repetitive behaviours. We found that the presence of a novel object did induce a moderate CORT response, but selection lines did not differ in the magnitude of this response. Furthermore, although both selection lines showed a robust CORT elevation to a subsequent restraint stressor, the CORT response was stronger in bold birds and this effect was specific to novel object exposure. Shy birds showed a strong positive phenotypic correlation between CORT concentrations following the novel object exposure and the subsequent restraint stress. Behaviourally, the selection lines differed in their response during novel object exposure: as predicted, bold birds more frequently approached the novel object and shy birds more strongly decreased overall locomotion during the novel object trial, but birds from both selection lines showed significant and similar frequencies of abnormal repetitive behaviours during novel object exposure. Our findings support the hypothesis that personality emerges as a result of correlated selection on behaviour and underlying endocrine mechanisms and suggest that the relationship between endocrine stress physiology and personality is context dependent

Differences in life expectancy between four Western countries and their Caribbean dependencies, 1980–2014

BackgroundIn the Caribbean, life expectancy in politically independent territories has increasingly diverged from that of territories that remained affiliated to their former colonizers. Because these affiliated territories differ in degree of political independence, they are not all governed in the same way. We assessed whether differences in life expectancy trends between Caribbean dependencies and their Western administrators were related to their degree of political independence, and which causes of death contributed to divergence or convergence in life expectancy.MethodsAnalysis of age-standardized death rates and decomposition of life expectancy differences between France, the Netherlands, UK, USA and their Caribbean dependencies by age and cause-of-death during the period 1980–2014.ResultsLife expectancy differences between Western countries and their dependencies have generally increased for men and narrowed for women, but trends have been much more favorable in the French- than in the Dutch-administered territories. The strongest contributions to widening gaps in life expectancy between Western countries and their dependencies were from mortality from cardiovascular diseases (ischemic heart disease) and external causes (homicide and traffic accidents).ConclusionDependencies with a stronger political affiliation to a Western country experienced more favorable life expectancy developments than dependencies that had more autonomy during the 1980–2014 period. The underlying mortality differences with Western countries are largely comparable among Caribbean territories but differ in magnitude, most notably for cardiovascular disease and external causes. This suggests that increases in a territory’s political autonomy impairs the diffusion of new knowledge and techniques, and/or reduces government’s effectiveness in implementing policies