The student-produced electronic portfolio in craft education

The authors studied primary school students’ experiences of using an electronic portfolio in their craft education over four years. A stimulated recall interview was applied to collect user experiences and qualitative content analysis to analyse the collected data. The results indicate that the electronic portfolio was experienced as a multipurpose tool to support learning. It makes the learning process visible and in that way helps focus on and improves the quality of learning. © ISLS.Peer reviewe

FIRE SIMULATIONS OF A FISHING RESEARCH VESSEL WITH FRP STRUCTURES

The fire safety effect of using fibre-reinforced polymer (FRP) as the primary construction material in a fishing research vessel was studied by fire simulations. The effect of FRP structures on fire development was assessed by comparing the simulated gas temperatures and potential heat releases with FRP and steel structures. The structural integrity of FRP structures was assessed using simulated temperatures of the structures as indicators of integrity. The effect of protective mineral wool and intumescent coating layers was also quantified. The results showed that despite the protection, the structural integrity of FRP bulkheads could be compromised in fire conditions. Mineral wool was found to be better protection than the intumescent coating: it can either prevent or postpone the pyrolysis of the FRP bulkhead, depending on the fire exposure

Situated Support for Choice of Representations

As more and more companies are augmenting their data to include semantics it is imperative that the choices made when choosing the modelling language are well founded in knowledge about the language and the domain in question. This work demonstrates how the Semiotic Quality Framework can facilitate the choice of the most suited language for a real world application. Computational and situated features are introduced as an extension to the framework

Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

Semiconductor nanowires made of high refractive index materials can couple the incoming light to specific waveguide modes that offer resonant absorption enhancement under the bandgap wavelength, essential for light harvesting, lasing and detection applications. Moreover, the non-trivial ellipticity of such modes can offer near field interactions with chiral molecules, governed by near chiral field. These modes are therefore very important to detect. Here, we present the photo-acoustic spectroscopy as a low-cost, reliable, sensitive and scattering-free tool to measure the spectral position and absorption efficiency of these modes. The investigated samples are hexagonal nanowires with GaAs core; the fabrication by means of lithography-free molecular beam epitaxy provides controllable and uniform dimensions that allow for the excitation of the fundamental resonant mode around 800 nm. We show that the modulation frequency increase leads to the discrimination of the resonant mode absorption from the overall absorption of the substrate. As the experimental data are in great agreement with numerical simulations, the design can be optimized and followed by photo-acoustic characterization for a specific application

Decreasing trend and changing indications of hysterectomy in Finland

Introduction Hysterectomy has been one of the most common surgical procedures in women in Finland. We studied the population-based trends of hysterectomy and its indications from 1986 to 2017. Material and methods A retrospective population-based cohort was created from the Care Register for Health Care by identifying women who had a hysterectomy from 1986 to 2017 and calculating the number of women from the Digital and Population Data Services Agency. We estimated the number and incidence of hysterectomy by period and age as well as by indication. We considered the primary diagnosis at the time of surgery as the indication of hysterectomy. Results The number of hysterectomies increased from 7492 procedures in 1986 to 12 404 procedures in 1998, and reduced substantially after that to 5971 procedures in 2017, the turning point being in 1999. The incidence rate of hysterectomy has decreased on average by 2.5% annually from 432.6 per 100 000 women in 1998-2001 to 224.5 per 100 000 women in 2014-2017. The median age at the time of hysterectomy has increased from 51 years in 1998-2001 to 55 years in 2014-2017. The cumulative burden of hysterectomy by age of 60 years has nearly halved from the first 4-year period (23%) to the last (12%). After 2010, the most common indication has been genital prolapse and incontinence, whereas earlier it was uterine fibroids. Conclusions The number and incidence of hysterectomies have fluctuated during the observation period 1986-2017 and decreased considerably during the past 17 years in Finland. This is probably a result of the availability of hormonal and other conservative treatment options for bleeding disorders and uterine fibroids. As hysterectomy practically removes the risk for endometrial cancer, the change in hysterectomy incidence over time emphasizes the importance of correcting endometrial cancer incidence according to hysterectomy incidence.Peer reviewe

Superior flame retardancy of cotton by synergetic effect of cellulose-derived nano-graphene oxide carbon dots and disulphide-containing polyamidoamines

Linear polyamidoamines containing disulphide groups (SS-PAAs) were prepared by polyaddition of L-cystine with 2,2-bisacrylamidoacetic acid (B-CYSS), N,N\u2032-methylenebisacrylamide (M-CYSS) and 1,4-bisacryloylpiperazine (BP-CYSS). They were evaluated as flame retardants for cotton, alone or with cellulose-derived nano-graphene oxide (nGO) carbon dots, to assess whether, due to their potential as radical scavengers, the latter would improve the already good performance of SS-PAAs. In vertical flame spread tests (VFST), cotton treated with 1% nGO burned as quickly as cotton, whereas B-CYSS, M-CYSS and BP-CYSS extinguished the flame at add-ons 65 12, 16 and 20%, respectively. Probably, the gaseous products of SS-PAA thermal degradation quenched the radicals involved in oxidation. Cotton treated with 8, 12 and 15%, respectively, of B-CYSS, M-CYSS and BP-CYSS burned completely, but further addition of 1% nGO either inhibited ignition or shortly extinguished the flame, demonstrating synergism between the two components. Synergism was confirmed by assessing the synergism effectiveness parameter for the residual mass fraction (RMF) and by comparing the calculated and experimental TG curves in air for the cotton/SS-PAA-nGO systems. In cone calorimetry tests, the presence of nGO did not improve the already good performances of SS-PAAs, supporting the hypothesis that the action of both takes place in the gas phase

On dimension reduction in Gaussian filters

A priori dimension reduction is a widely adopted technique for reducing the computational complexity of stationary inverse problems. In this setting, the solution of an inverse problem is parameterized by a low-dimensional basis that is often obtained from the truncated Karhunen-Loeve expansion of the prior distribution. For high-dimensional inverse problems equipped with smoothing priors, this technique can lead to drastic reductions in parameter dimension and significant computational savings. In this paper, we extend the concept of a priori dimension reduction to non-stationary inverse problems, in which the goal is to sequentially infer the state of a dynamical system. Our approach proceeds in an offline-online fashion. We first identify a low-dimensional subspace in the state space before solving the inverse problem (the offline phase), using either the method of "snapshots" or regularized covariance estimation. Then this subspace is used to reduce the computational complexity of various filtering algorithms - including the Kalman filter, extended Kalman filter, and ensemble Kalman filter - within a novel subspace-constrained Bayesian prediction-and-update procedure (the online phase). We demonstrate the performance of our new dimension reduction approach on various numerical examples. In some test cases, our approach reduces the dimensionality of the original problem by orders of magnitude and yields up to two orders of magnitude in computational savings

Thermo-mechanical analysis of laminated composites exposed to fire

This presentation introduces a numerical model for the thermo-mechanical analysis of laminated composite structures under the fire action. The coupling between the thermal and mechanical behaviour is considered in weak form (temperatures field modify mechanical properties but displacements field do not modify thermal properties). The thermal part of model is based on the approach presented in Henderson et al. (1985). This model takes into account the energy transfer processes of heat conduction, pyrolysis of the polymer matrix, and diffusion of decomposition gases. The mechanical behaviour of the composites is based on the serial/parallel mixing theory (Rastellini et al., 2008) which is modified to take into account the thermal degradation of the mechanical properties. Numerical results obtained with this model are compared with some experimental tests presented in the literature. Application of the developed model to the analysis of fire scenarios in composite ships is evaluated

Microwave-assisted methacrylation of chitosan for 3D printable hydrogels in tissue engineering

Light processable natural polymers are highly attractive for 3D printing of biomedical hydrogels with defined geometries and sizes. However, functionalization with photo-curable groups, such as methacrylate or acrylate groups, is required. Here, we investigated a microwave-assisted process for methacrylation of chitosan to replace conventional methacrylation processes that can be time consuming and tedious. The microwave-assisted methacrylation reaction was optimized by varying the synthesis parameters such as the molar ratio of chitosan to the methacrylic agent, the launch and reaction times and process temperature. The optimized process was fast and efficient and allowed tuning of the degree of substitution and thereby the final hydrogel properties. The successful methacrylation and degree of substitution were verified by H-1 NMR and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The influence of the degree of methacrylation on photo-rheology, mechanical stiffness, swelling degree and gel content was evaluated. Furthermore, favourable 3D printability, enzymatic degradability, biocompatibility, cell migration and proliferation were demonstrated giving promise for further applications in tissue engineering

From multiple perspectives to shared understanding

The aim of this study was to explore how learners operating in a small group reach shared understanding as they work out joint research questions and build a theoretical framework and to identify the resources and tools they used in the process. The learners’ own interpretations of their group activities and learning were also taken into account. The data, consisting of group discussions and the documents produced by the group, were subjected to a qualitative content analysis. The group members employed a variety of resources and tools to exchange their individual perspectives and achieve shared understanding. Summaries of relevant literature laid a foundation for the group’s theoretical discussions. Reflective comparisons between their book knowledge and their personal experiences of online interaction and collaboration were frequent, suggesting that such juxtapositions may have enhanced their learning by intertwining the content to be mastered and the activities entailed by this particular content