Rezension: SCHLEMMINGER, GERALD: La pédagogie Freinet et l'enseignement des langues vivantes. Approche historique, systématique et théorique

Ce que G. Schlemminger constate dans son chapitre d'introduction vaut la peine d'être lu attentivement car, en un bref aperçu, il décrit les invariants et la situation actuelle de l'enseignement des langues vivantes. Sa critique de la situation actuelle ne se veut ni facile ni hâtive; son ouvrage représente une étude approfondie des paradigmes référentiels à l'enseignement des langues. Il fournit la preuve que c'est dans la convergence des différentes théories de l'apprentissage, avec la multitude des pratiques de la pédagogie Freinet, que l'on trouvera une nouvelle voie pour l'enseignement des langues. Voie d'autant plus difficile à trouver que les contraintes - vraies ou simplement supposées - de progression, d'assimilation ou de mémorisation semblent favoriser un apprentissage guidé, centré sur l'enseignant(e) qui détient les rênes. La question posée par l'auteur initialement étant "de savoir si les savoir-faire pratiqués majoritairement sont les seuls possibles", celle-ci retiendra notre attention.Les deux grands objectifs de la présente étude sont l'analyse de l'évolution historique des techniques Freinet dans les classes de langues et la comparaison de ces techniques avec les concepts et pratiques didactiques et pédagogiques de l'époque respective. Pour ce faire, G. Schlemminger a constitué un corpus de documents, sur la base de 131 articles publiés dans des revues pédagogiques, qui relatent des expériences de pédagogie Freinet en classes de langues

The mutual patterning between the developing nephron and its covering tissues—valid reasons to rethink the search for traces left by impaired nephrogenesis

After 175 dynamic years the name Springer stands for a globally active publisher dedicated to the advancement of science, putting its authors and editors at the heart of the company’s publishing activities

Entwicklung und Evaluierung 3-O-modifizierter Derivate von Kohlenhydrat-Bis(oxazolinen)

[no abstract

The interstitium at the developing nephron in the fetal kidney during advanced pregnancy — a microanatomical inventory

Background A series of noxae can evoke the termination of nephron formation in preterm and low birth weight babies. This results in oligonephropathy with severe consequences for health in the later life. Although the clinical parameters have been extensively investigated, little is known about the initial damage. Previous pathological findings indicate the reduction in width of the nephrogenic zone and the lack of S-shaped bodies. Current morphological investigations suggest that due to the mutual patterning beside the forming nephron, also its structural neighbors, particularly the interjacent interstitium, must be affected. However, beside the findings on integrative and mastering functions, systematic microanatomical data explaining the configuration of the interstitium at the developing nephron in the fetal kidney during advanced pregnancy is not available. Therefore, this work explains the typical features. Results The generated data depicts that the progenitor cells, nephrogenic niche, pretubular aggregate, and mesenchymal-to-epithelial transition are restricted to the subcapsular interstitium. During the proceeding development, only the distal pole of the renal vesicles and comma- and S-shaped bodies stays in further contact with it. The respective proximal pole is positioned opposite the peritubular interstitium at the connecting tubule of an underlying but previously formed nephron. The related medial aspect faces the narrow peritubular interstitium of a collecting duct (CD) ampulla first only at its tip, then at its head, conus, and neck, and finally at the differentiating CD tubule. The lateral aspect starts at the subcapsular interstitium, but then it is positioned along the wide perivascular interstitium of the neighboring ascending perforating radiate artery. When the nephron matures, the interstitial configuration changes again. Conclusions The present investigation illustrates that the interstitium at the forming nephron in the fetal kidney consists of existing, transient, stage-specific, and differently far matured compartments. According to the developmental needs, it changes its shape by formation, degradation, fusion, and rebuilding

Installation of the developing nephron in the fetal human kidney during advanced pregnancy

Background The kidneys of preterm and low birth weight babies reflect vulnerability, since several noxae can evoke the termination of nephron formation. This again leads to oligonephropathy with severe consequences for health in the later life. While the clinical parameters have been intensely investigated, only little is known about the initial traces left by the noxae. For the fetal human kidney, solely the lack of basophilic S-shaped bodies and the reduction in width of the nephrogenic zone were registered. It is not known in how far also the involved progenitor cells, the earlier nephron stages, the collecting duct (CD) ampullae, and the local interstitium are collaterally harmed. Aim The interstitium at the forming nephron is heterogeneously structured. Thereby, it fulfills quite different mastering and integrative tasks. Since data dealing with the installation of a nephron is not available, the microanatomical features were recorded. Results The microscopic specimens show that the installation of the transient stages of nephron anlage is not synchronized. Instead, it is controlled within a nephrogenic compartment of the nephrogenic zone. It starts near the renal capsule by positioning the nephrogenic niche so that the nephrogenic progenitor cells face the epithelial progenitor cell at the tip of a CD ampulla. Then, the induced nephrogenic progenitor cells assimilate in the pretubular aggregate. While its medial part remains opposite the head of the CD ampulla, at its proximal end, the primitive renal vesicle is formed. Only a part of it separates to stick to the section border between the head and conus of the CD ampulla. This marks the link with the future connecting tubule at the distal pole of the extending renal vesicle. Meanwhile, the proximal pole is mounted next to the connecting tubule of an earlier developed nephron. The resulting two-point mounting serves a common elongation of the conus at the CD ampulla and the medial aspect of the comma-shaped body. In the S-shaped body, it supports to defoliate the arising glomerulus and to link it with the perforating radiate artery at its deep lateral aspect. Conclusions The investigation depicts that the installation is an interactive process between the stages of nephron anlage and its structural neighbors. A special meaning has the interjacent interstitium. It is vital for the positioning, shaping, and physiological integration. Due to its special location, this is mainly exposed to noxae

Radial Expansion of the Nephrogenic Zone in the Fetal Human Kidney During Advanced Pregnancy: A Microanatomical Look at a Little Noticed Process

Introduction: The experiences with preterm and low birth weight babies indicate a special vulnerability of their kidneys, since different kinds of noxae can evoke the termination of nephron formation. This leads to oligonephropathy, which is associated with serious consequences for health in the later stages of life. While the clinical aspects have been intensely investigated, only few pathological data point to the initial traces left by the noxae. Up to this date, only the reduction in the width of the nephrogenic zone (NZ) and the lack of here occurring basophilic S-shaped bodies were reported. Methods and Materials: The relationship between the arising nephron and its structural neighbors changes throughout the developmental progress. Locally, this determines the vertical width of the NZ reflected by the radial expansion of both the parenchyma and the interstitium. Since information about the origin, the site, and the involved structures is not available, the related microanatomical features were recorded. Results: The data reveal that the renal vesicles, comma-shaped bodies, and S-shaped bodies are unequally distributed in the NZ. Due to their progressive sizes, it has an influence on the local vertical width of the NZ. This parameter is registered as the distance between the inner side of the renal capsule and the proximal pole of the respective stage of the nephron anlage. The vertical width can be further subdivided: the constant height of the district of progenitor cell recruitment and the variable height of the area of nephron shaping. Exclusively here, the radial expansion of the shaping nephron stages can be noticed. It starts at the section border between the head and the conus of the related collecting duct ampulla by positioning the primitive renal vesicle. While the respective proximal pole stays mounted next to the connecting tubule of a previously developed nephron, the distal pole sticks between the head and the conus at the CD ampulla for linking the future connecting tubule. This causes that henceforth the medial aspect of the extending renal vesicle, comma-shaped body, or S-shaped body stages radially expands in close proximity to the elongating conus of the CD ampulla. Conclusion: Between the arising nephron stages and the elongating conus of the CD ampulla, a linked radial expansion occurs. This new finding is essential to identify the extent of targeting of noxae that subsequently leads to a reduction in the width of the NZ

The influence of strain rate on the mechanical behaviour of structural steel

Die Ermittlung von verlässlichen Werkstoffdaten bei hohen Beanspruchungsgeschwindigkeiten stellt versuchstechnisch noch immer eine große Herausforderung dar, obwohl die Untersuchung der dehnratenabhängigen Beeinflussung des Werkstoffverhaltens von Stahl bereits seit langem Gegenstand der Forschung ist. Zu üblichen Baustählen liegen Untersuchungen bis heute nicht in einem Umfang vor, der für eine für FE-Simulationen taugliche Beschreibung des Materialverhaltens zufriedenstellend wäre. In dieser Arbeit wurde die dehnratenabängige Beeinflussung der Festigkeits- und Verformungskennwerte von Baustahl anhand von Zugversuchen unter Variation der Beanspruchungsgeschwindigkeit untersucht. Es konnte gezeigt werden, dass sowohl Festigkeits- als auch Verformungskennwerte der Baustähle teilweise signifikant dehnratenabhängig sind. Dies führt dazu, dass die Fließkurvenform und -lage durch die Beanspruchungsgeschwindigkeit beeinflusst wird. Die Beeinflussung der Dehnratenempfindlichkeit wurde in dieser Arbeit anhand der unteren Streckgrenze untersucht. Es konnte gezeigt werden, dass die Dehnratenempfindlichkeit mit Abnahme der quasistatischen unteren Streckgrenze und mit Zunahme des mittleren Ferritkorndurchmessers zunimmt. Die Entwicklung der Dehnratenempfindlichkeit über die Kerbschlagarbeit entspricht qualitativ dem Verlauf bei Darstellung über die quasistatische untere Streckgrenze und kann letztlich ebenfalls anhand der Korngröße erklärt werden. Die in dieser Arbeit untersuchten bestehenden Modelle gehen einem multiplikativen Ansatz nach, der die Dehnratenverfestigung anhand eines Skalierungsfaktors berücksichtigt. Die Ermittlung eines Parametersatzes, mit der eine hohe Approximationsgüte für den gesamten Dehnratenbereich und alle Verformungsniveaus erreicht wird, war für keines der bestehenden Modelle möglich. Das in dieser Arbeit vorgestellte neue Materialmodell verfolgt den Ansatz der Trennung und getrennten Approximation von Fließplateau und Verfestigungskurve bis zur Gleichmaßdehnung. Für die Beschreibung der Verfestigungskurve wurden bekannte Verfestigungsmodelle verwendet, deren Modellparameter hinsichtlich ihrer Dehnratenabhängigkeit untersucht und wiederum mithilfe von Ansatzfunktionen approximiert wurden. Dies ermöglicht es, das Verfestigungsverhalten in Abhängigkeit der Dehnrate darzustellen. Umgekehrt wird die Dehnratenverfestigung des Baustahls in Abhängigkeit des betrachteten Verformungsniveaus beschrieben.The determination of reliable material data at high strain rates still represents a major challenge in the field of testing, although the study of strain rate-dependent influencing of the material behaviour of steel has been the subject of research for a long time. Studies on conventional structural steels to date are not available to a degree which would be satisfactory for a description of the material behaviour suitable for FE simulations. In this work, the strain rate dependent influence on the strength and deformation characteristics of structural steel was investigated by means of tensile tests with variation of the strain rate. It could be shown that both strength and deformation characteristics of structural steels are significantly strain rate dependent. Thus the shape of the flow curve is influenced by the strain rate. The influence on the strain rate sensitivity was investigated on the basis of the lower yield strength. It could be shown that the strain rate sensitivity increases with decrease of the quasistatic lower yield strength and with an increase of the mean ferrite grain diameter. The development of the strain rate sensitivity over the notch impact energy qualitatively corresponds to the course when represented by the quasistatic lower yield strength and can ultimately also be explained on the basis of the grain size. The existing models examined in this thesis follow a multiplicative approach, which considers the strain rate hardening on the basis of a scaling factor. The determination of a parameter set with which a high approximation quality for the entire strain rate range and all deformation levels is achieved was not possible for any of the existing models. The new material model presented in this work pursues the approach of separation and separate approximation of flow plateau and hardening curve to uniform elongation. For the description of the hardening curve, known hardening models were used. The strain-rate-dependent change of the model parameters was approximated by means of functions. This makes it possible to represent the hardening behaviour as a function of the strain rate. Furthermore, the strain rate hardening of the structural steel is described as a function of the considered deformation level

Cell Projections and Extracellular Matrix Cross the Interstitial Interface within the Renal Stem/Progenitor Cell Niche: Accidental, Structural or Functional Cues?

Background: During nephron induction, morphogenetic molecules are reciprocally exchanged between epithelial and mesenchymal stem/progenitor cells within the renal stem/progenitor cell niche. That these molecules remain concentrated, it is assumed that both cell populations stand in close contact to each other. However, recently published data illustrate that epithelial and mesenchymal cells are separated by an astonishingly wide interstitial interface. Methods: To gain deeper morphological insights into the spatial distribution of mesenchymal and epithelial stem/progenitor cells, the embryonic zone of neonatal rabbit kidney was fixed either with glutaraldehyde (GA) or in a combination with cupromeronic blue, ruthenium red or tannic acid. Transmission electron microscopy was then performed on exactly orientated sections. Results: Conventional fixation with GA illustrates that epithelial and mesenchymal stem/progenitor cells are separated by a bright but inconspicuously looking interstitial interface. In contrast, fixation of specimens in GA containing cupromeronic blue, ruthenium red or tannic acid elucidates that part of the interstitial interface exhibits a special extracellular matrix extending like woven strands between mesenchymal and epithelial stem/progenitor cells. In parallel, filigree projections from mesenchymal stem/progenitor cells cross the interstitial interface to penetrate the basal lamina of epithelial cells. Fusion of the plasma membranes cannot be observed. Instead, touching mesenchymal cell projections form a cone at the contact site with tunneling nanotubes. Conclusions: The results demonstrate that the contact between mesenchymal and epithelial stem/progenitor cells does not form accidentally but physiologically and appears to belong to a suspected system involved in the exchange of morphogenetic information

Effect of the Administration of Alpha-Lipoic Acid on Contrast Sensitivity in Patients with Type 1 and Type 2 Diabetes

The aim of this study was to estimate the effects of oral supplementation of alpha-lipoic acid (ALA) on contrast sensitivity (CS) in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). The study included 12 patients with T1DM aged 43±12 years, 48 patients with T2DM aged 59±10 years, and 20 control subjects aged 33±8 years. Patients from each studied group, including the control group, were randomly assigned to receive 300 mg of ALA orally once daily for 3 months. CS was evaluated with the Functional Acuity Contrast Test (FACT, Stereo Optical). In the group of patients with T1DM receiving ALA for 3 months CS remained stable and improved in those with T2DM. Reduction of CS in both T1DM and T2DM patients without alpha-lipoic acid supplementation was observed. In the control group on alpha-lipoic acid supplementation, CS improvement was noticed at one spatial frequency. Changes in the CS were observed, despite stable visual acuity and eye fundus image in all studied subjects. Our study demonstrated that oral administration of alpha-lipoic acid had influence on CS in both T1DM and T2DM patients