Організаційно-педагогічні умови підготовки майбутнього педагога-музиканта в системі неперервної освіти

У статті досліджуються організаційно-педагогічні умови підготовки майбутнього педагога-музиканта в системі неперервної освіти.В статье исследуются организационно-педагогические условия подготовки будущего педагога-музыканта в системе непрерывного образования

The effect of periprosthetic bone loss on the failure risk of tibial total knee arthroplasty

The effect of long-term periprosthetic bone loss on the process of aseptic loosening of tibial total knee arthroplasty (TKA) is subject to debate. Contradicting studies can be found in literature, reporting either bone resorption or bone formation before failure of the tibial tray. The aim of the current study was to investigate the effects of bone resorption on failure of tibial TKA, by simulating clinical postoperative bone density changes in finite element analysis (FEA) models and FEA models were created of two tibiae representing cases with good and poor initial bone quality which were subjected to a walking configuration and subsequently to a traumatic stumbling load. Bone failure was simulated using a crushable foam model incorporating progressive yielding. Repetitive loading under a level walking load did not result in failure of the periprosthetic bone in neither the good nor poor bone quality tibia at the baseline bone densities. When applying a stumble load, a collapse of the tibial reconstruction was noticed in the poor bone quality model. Incorporating postoperative bone loss led to a significant increase of the failure risk, particularly for the poor bone quality model in which subsidence of the tibial component was substantial. Our results suggest bone loss can lead to an increased risk of a collapse of the tibial component, particularly in case of poor bone quality at the time of surgery. The study also examined the probability of medial or lateral subsidence of the implant and aimed to improve clinical implications. The FEA model simulated plastic deformation of the bone and implant subsidence, with further validation required via mechanical experiments.</p

Bélemnites de Valanginien : Nouvelles observations taxonomiques et stratigraphiques

Six new Valanginian belemnite species (Duvalia crassa sp. nov., Duvalia elongata sp. nov., Duvalia kleini sp. nov., Duvalia superconstricta sp. nov., Castellanibelus vaubellensis sp. nov., and "Hibolithes" lebresensis sp. nov.) are described here and two species (Duvalia aff. elongata and "Hibolithes" aff. pistilliformis (Blainville, 1827)) are left in open nomenclature. They come from both the distal and proximal parts of the Vocontian Basin in south-east France and the Baetic Cordillera in south-east Spain. In addition lectotypes are selected for Castellanibelus orbignyanus (Duval-Jouve, 1841), Castellanibelus picteti (Mayer, 1866), and Duvalia lata (Blainville, 1827).Six espèces nouvelles de bélemnites valanginiennes (Duvalia crassa sp. nov., Duvalia elongata sp. nov., Duvalia kleini sp. nov., Duvalia superconstricta sp. nov., Castellanibelus vaubellensis sp. nov. et "Hibolithes" lebresensis sp. nov.) sont décrites ici alors que deux autres (Duvalia aff. elongata et "Hibolithes" aff. pistilliformis (Blainville, 1827)) sont laissées en nomenclature ouverte. Elles proviennent des parties distales et proximales du bassin vocontien dans le sud-est de la France et des Cordillères bétiques dans le sud-est de l'Espagne. De plus, des lectotypes sont désignés pour les espèces Castellanibelus orbignyanus (Duval-Jouve, 1841), Castellanibelus picteti (Mayer, 1866), et Duvalia lata (Blainville, 1827)

Bélemnites néocomienne des régions méditerranéennes, 3ème partie : Bélemnites de l'intervalle Valanginien-Hauterivien

Les travaux classiques mais anciens de RASPAIL (1829, 1830) et DUVAL-JOUVE (1841) décrivent une grande variété d'espèces de bélemnites, provenant essentiellement du Crétacé inférieur de la région de Castellane-Peyroules (Alpes de Haute-Provence, France). Cette nouvelle contribution s'articule autour de la distribution biostratigraphique des bélemnites décrites précédemment car jusqu'à présent cet aspect avait été négligé. Le canevas biostratigraphique est calibré avec les successions lithologiques et les associations fauniques (ammonitofaune) de plusieurs affleurements dans cette région. Des données supplémentaires ont été obtenues à partir de coupes levées dans d'autres secteurs des Alpes de Haute-Provence: La Lagne, Les Allaves et Pas d'Escale. De plus, afin de mieux comprendre la distribution stratigraphique des bélemnites du Valanginien supérieur au sein de niveaux condensés glauconitiques ces associations sont comparées avec les bélemnites de milieux de dépôt plus profonds à Angles, à la Source de l'Asse de Moriez et à Cheiron, et avec celles des environs de La Charce et Vergol qui correspondent à des milieux plus profonds encore.The classical papers of RASPAIL (1829, 1830) and DUVAL-JOUVE (1841) described a wide range of belemnite species, mainly from the Lower Cretaceous of the Castellane-Peyroules area (Alpes de Haute-Provence, France). The present work focuses mainly on the biostratigraphy of these previously described belemnite taxa for their stratigraphic relationships had not been determined precisely. Here, biostratigraphy is related to the lithologic successions and faunal associations (ammonites) of various outcrops in the area studied. Complementary data were obtained from the La Lagne, Les Allaves and Pas d'Escale sections (Alpes de Haute-Provence, France). And, in order to attain a better understanding of the stratigraphic distribution of Late Valanginian belemnites in condensed glauconitic deposits, these assemblages are compared with belemnites from deeper water successions in the Angles, Source de l'Asse de Moriez, Cheiron areas and those in the vicinity of La Charce and Vergol that are even deeper

Strain shielding in trabecular bone at the tibial cement-bone interface

Item does not contain fulltextAseptic loosening of the tibial component remains the leading cause for revision surgery in total knee arthroplasty (TKA). Understanding the mechanisms leading to loss of fixation can offer insight into preventative measures to ensure a longer survival rate. In cemented TKA, loosening occurs at the cement-trabecular interface probably due to a stress-shielding effect of the stiffer implant material in comparison with bone. Using finite element models of lab-prepared tibial cement-trabeculae interface specimens (n=4) based on micro-CT images, this study aims to investigate the micromechanics of the interlock between cement and trabecular bone. Finite element micromotion between cement and trabeculae and bone strain were compared in the interdigitated trabeculae as well as strain in the bone distal to the interface. Lab-prepared specimens and their FE models were assumed to represent the immediate post-operative situation. The cement layer was removed in the FE models while retaining the loading conditions, which resulted in FE models that represented the pre-operative situation. Results showed that micromotion and bone strain decrease when interdigitation depth increases. Bone-cement micromotion and bone strain at the distal interdigitated region showed a dependence on bone volume fraction. Comparing the immediate post-operative and pre-operative situations, trabeculae embedded deep within the cement generally showed the highest level of strain-shielding. Strain shielding of interdigitated bone, in terms of reduction in compressive strains, was found to be between 35 and 61 % for the four specimens. Strain adaptive remodeling could thus be a plausible mechanism responsible for loss of interdigitated bone

Computational tibial bone remodeling over a population after total knee arthroplasty:A comparative study

Periprosthetic bone loss is an important factor in tibial implant failure mechanisms in total knee arthroplasty (TKA). The purpose of this study was to validate computational postoperative bone response using longitudinal clinical DEXA densities. Computational remodeling outcome over a population was obtained by incorporating the strain‐adaptive remodeling theory in finite element (FE) simulations of 26 different tibiae. Physiological loading conditions were applied, and bone mineral density (BMD) in three different regions of interest (ROIs) was considered over a postoperative time of 15 years. BMD outcome was compared directly to previously reported clinical BMD data of a comparable TKA cohort. Similar trends between computational and clinical bone remodeling over time were observed in the two proximal ROIs, with most rapid bone loss taking place in the initial months after TKA and BMD starting to level in the following years. The extent of absolute proximal BMD change was underestimated in the FE population compared with the clinical subject group, which might be the result of significantly higher initial clinical baseline BMD values. Large differences in remodeling response were found in the distal ROI, in which resorption was measured clinically, but a large BMD increase was predicted by the FE models. Multiple computational limitations, related to the FE mesh, loading conditions, and strain‐adaptive algorithm, likely contributed to the extensive local bone formation. Further research incorporating subject‐specific comparisons using follow‐up CT scans and more extensive physiological knee loading is recommended to optimize bone remodeling more distal to the tibial baseplate

Maak het waar(d) : elektronisch informatieverkeer voor kleinere spelers in de keten

Kleine partijen - MKB-ers en consumenten - spelen vaak een sleutelrol in het realiseren van nieuwe concepten voor\ud elektronische communicatie in ketens en netwerken. Juist bij deze kleinere, en vaak talrijke, partijen spelen echter allerlei\ud obstakels die adoptie bemoeilijken

Low ranks make the difference: how achievement goals and ranking information affect cooperation intentions

This investigation tested the joint effect of achievement goals and ranking information on information exchange intentions with a commensurate exchange partner. Results showed that individuals with performance goals were less inclined to cooperate with an exchange partner when they had low or high ranks, relative to when they had intermediate ranks. In contrast, mastery goal individuals showed weaker cooperation intentions when their ranks were higher. Moreover, participants’ reciprocity orientation was found to mediate this interaction effect of achievement goals and ranking information. These findings suggest that mastery goals are more beneficial for exchange relationships than performance goals in terms of stronger reciprocity orientation and cooperation intentions, but only among low-ranked individuals

Mitosene-DNA adducts. Characterization of two major DNA monoadducts formed by 1,10-bis(acetoxy)-7-methoxymitosene upon reductive activation

Reductive activation of racemic 1,10-bis(acetoxy)-7-methoxymitosene WV15 in the presence of DNA, followed by enzymatic digestion and HPLC analysis, revealed the formation of various DNA adducts. Reduction is a necessary event for adduct formation to occur. This reductive activation was performed under hypoxic conditions in various ways:  (1) chemically, using a 2-fold excess of sodium dithionite (Na2S2O4), (2) enzymatically using NADH-cytochrome c reductase, (3) electrochemically on a mercury pool working electrode, and (4) catalytically, using a H2/PtO2 system. Five different mitosene−DNA adducts were detected. These adducts were also present when poly(dG-dC) was used instead of DNA, but were absent with poly(dA-dT). All were shown to be adducts of guanine. Reduction of 1,10-dihydroxymitosene WV14 in the presence of DNA did not result in detectable adduct formation, demonstrating the importance of good leaving groups for efficient adduct formation by these mitosenes. Finally, two of the adducts were isolated and their structures elucidated, using mass spectrometry, 1H NMR and circular dichroism (CD). The structures were assigned as the diastereoisomers N2-(1‘ ‘-n-hydroxymitosen-10‘ ‘-yl), 2‘-deoxyguanosine (n = α or β). These type of adducts, in which the mitosene C-10 is covalently bonded to the N-2 of a guanosylic group, are different from the well-known mitomycin C 2‘-deoxyguanosine monoadducts, that is linked via the mitomycin C C-1 position, demonstrating that the order of reactivity of the C-1 and C-10 in these mitosenes is reversed, as compared to mitomycin C. The 7-methoxy substituent of WV15 is a likely factor causing this switch. Evidence is presented that the 7-substituent of mitosenes also influences their DNA alkylation site. Adducts 4 and 5 represent the first isolated and structurally characterized covalent adducts of DNA and a synthetic mitosene