Neuronal differentiation influences progenitor arrangement in the vertebrate neuroepithelium

Cell division, movement and differentiation contribute to pattern formation in developing tissues. This is the case in the vertebrate neural tube, in which neurons differentiate in a characteristic pattern from a highly dynamic proliferating pseudostratified epithelium. To investigate how progenitor proliferation and differentiation affect cell arrangement and growth of the neural tube, we used experimental measurements to develop a mechanical model of the apical surface of the neuroepithelium that incorporates the effect of interkinetic nuclear movement and spatially varying rates of neuronal differentiation. Simulations predict that tissue growth and the shape of lineage-related clones of cells differ with the rate of differentiation. Growth is isotropic in regions of high differentiation, but dorsoventrally biased in regions of low differentiation. This is consistent with experimental observations. The absence of directional signalling in the simulations indicates that global mechanical constraints are sufficient to explain the observed differences in anisotropy. This provides insight into how the tissue growth rate affects cell dynamics and growth anisotropy and opens up possibilities to study the coupling between mechanics, pattern formation and growth in the neural tube

VIRTUAL MACHINES IN EDUCATION – CNC MILLING MACHINE WITH SINUMERIK 840D CONTROL SYSTEM

Machining process nowadays could not be conducted without its inseparable element: cutting edge and frequently numerically controlled milling machines. Milling and lathe machining centres comprise standard equipment in many companies of the machinery industry, e.g. automotive or aircraft. It is for that reason that tertiary education should account for this rising demand. This entails the introduction into the curricula the forms which enable visualisation of machining, milling process and virtual production as well as virtual machining centres simulation. Siemens Virtual Machine (Virtual Workshop) sets an example of such software, whose high functionality offers a range of learning experience, such as: learning the design of machine tools, their configuration, basic operation functions as well as basics of CNC

THE USE OF COMPUTER ALGEBRA SYSTEMS IN THE TEACHING PROCESS

This work discusses computational capabilities of the programs belonging to the CAS (Computer Algebra Systems). A review of commercial and non-commercial software has been done here as well. In addition, there has been one of the programs belonging to the this group (program Mathcad) selected and its application to the chosen example has been presented. Computational capabilities and ease of handling were decisive factors for the selection

Drivers of structural features in gene regulatory networks: From biophysical constraints to biological function

Living cells can maintain their internal states, react to changing environments, grow, differentiate, divide, etc. All these processes are tightly controlled by what can be called a regulatory program. The logic of the underlying control can sometimes be guessed at by examining the network of influences amongst genetic components. Some associated gene regulatory networks have been studied in prokaryotes and eukaryotes, unveiling various structural features ranging from broad distributions of out-degrees to recurrent "motifs", that is small subgraphs having a specific pattern of interactions. To understand what factors may be driving such structuring, a number of groups have introduced frameworks to model the dynamics of gene regulatory networks. In that context, we review here such in silico approaches and show how selection for phenotypes, i.e., network function, can shape network structure

Modelling and Validation of the Composite Shell of a Train Seat

The subject of the modelling work and the conducted experiments is the composite shell of a train seat. The activities carried out involved designing the geometry, planning the material structure, and selecting the materials to be used. The shell was built using polymer matrix fibrous composites (i.e. FRP – Fibre Reinforced Polymer – composites), which are lighter than steel and comply with the relevant standards for strength and safety at the same time. This was followed by creating a computational model for the shell and conducting a strength analysis in accordance with the guidelines of the relevant industry standard and strength hypotheses adopted for FRP composites. The calculations were conducted using ANSYS Composite PrepPost software based on the finite element method. The article offers a strength analysis of an optimised composite shell of a train seat. Based on the guidelines obtained as a result of the conducted modelling work, a physical prototype (validation model) of the seat was created. Hot vacuum lamination technology was applied in the production process. The experimental validation of the model, producing a positive result, was conducted using a test stand owned by S.Z.T.K. TAPS – Maciej Kowalski

Modelowanie i walidacja wytrzymałościowa kompozytowej skorupy nośnej fotela kolejowego

Przedmiotem prac modelowych i badań doświadczalnych jest kompozytowa skorupa nośna fotela kolejowego. Zaprojektowano kształt geometryczny i strukturę materiałową konstrukcji oraz dobrano materiały. Do budowy skorupy wykorzystano kompozyty włókniste o osnowie polimerowej (kompozyty FRP – Fiber Reinforce Polimer), które są lżejsze w porównaniu ze stalą i jednocześnie zapewniają odpowiednie standardy z zakresu wytrzymałości i bezpieczeństwa. Opracowano obliczeniowy model skorupy i przeprowadzono analizę wytrzymałościową zgodnie z wytycznymi branżowej normy oraz hipotezami wytrzymałościowymi dotyczącymi kompozytów FRP. Obliczenia przeprowadzono za pomocą oprogramowania ANSYS (Ansys Composite PrepPost), bazującego na metodzie elementów skończonych. W artykule przedstawiono analizę wytrzymałościową zoptymalizowanego modelu kompozytowej skorupy nośnej fotela. Na podstawie wytycznych z prac modelowych wytworzono model fi zyczny (walidacyjny), w technologii laminowania próżniowego na gorąco. Walidację doświadczalną modelowania z wynikiem pozytywnym przeprowadzono na stanowisku badawczym fi rmy S.Z.T.K. TAPS – Maciej Kowalski