Mechanisms of angiogenesis in tumour

Angiogenesis is essential for tumour growth and metastasis. Antiangiogenic factor-targeting drugs have been approved as first line agents in a variety of oncology treatments. Clinical drugs frequently target the VEGF signalling pathway during sprouting angiogenesis. Accumulating evidence suggests that tumours can evade antiangiogenic therapy through other angiogenesis mechanisms in addition to the vascular sprouting mechanism involving endothelial cells. These mechanisms include (1) sprouting angiogenesis, (2) vasculogenic mimicry, (3) vessel intussusception, (4) vascular co-option, (5) cancer stem cell-derived angiogenesis, and (6) bone marrow-derived angiogenesis. Other non-sprouting angiogenic mechanisms are not entirely dependent on the VEGF signalling pathway. In clinical practice, the conversion of vascular mechanisms is closely related to the enhancement of tumour drug resistance, which often leads to clinical treatment failure. This article summarizes recent studies on six processes of tumour angiogenesis and provides suggestions for developing more effective techniques to improve the efficacy of antiangiogenic treatment

Багатомовність в Україні та її специфіка

У статті висвітлюються аспекти явища багатомовності, характерні для України як для національної держави, котра продовжує перебувати на стадії трансформації державно-політичної, соціально-економічної, духовної систем. Підкреслюється актуальність «аксіоми національної державності», згідно з якою українська мова, яка є рідною для більшості членів титульної нації країни, має бути єдиною державною мовою.The article studies the aspects of the phenomenon of multilingualism which are characteristic of Ukraine as a national state that remains at the stage of final forming complicated by the transformation of state political, social, economic and spiritual systems. The author underlines actuality of “the axiom of national statehood” that expects Ukrainian to be official language because it is native for the most of members of a titular nation in Ukraine

Identification of Rice Transcription Factors Associated with Drought Tolerance Using the Ecotilling Method

The drought tolerance (DT) of plants is a complex quantitative trait. Under natural and artificial selection, drought tolerance represents the crop survival ability and production capacity under drought conditions (Luo, 2010). To understand the regulation mechanism of varied drought tolerance among rice genotypes, 95 diverse rice landraces or varieties were evaluated within a field screen facility based on the ‘line–source soil moisture gradient’, and their resistance varied from extremely resistant to sensitive. The method of Ecotype Targeting Induced Local Lesions in Genomes (Ecotilling) was used to analyze the diversity in the promoters of 24 transcription factor families. The bands separated by electrophoresis using Ecotilling were converted into molecular markers. STRUCTURE analysis revealed a value of K = 2, namely, the population with two subgroups (i.e., indica and japonica), which coincided very well with the UPGMA clusters (NTSYS-pc software) using distance-based analysis and InDel markers. Then the association analysis between the promoter diversity of these transcription factors and the DT index/level of each variety was performed. The results showed that three genes were associated with the DT index and that five genes were associated with the DT level. The sequences of these associated genes are complex and variable, especially at approximately 1000 bp upstream of the transcription initiation sites. The study illuminated that association analysis aimed at Ecotilling diversity of natural groups could facilitate the isolation of rice genes related to complex quantitative traits

Optimisation du compromis endurance/confort des pièces de liaison au sol en roulage numérique

La simulation du système de liaison au sol est pratiquée intensivement en amont des projets chez Renault afin de vérifier si les prestations comme l’endurance et le confort sont respectées. Toutefois, les validations numériques sont réalisées indépendamment par des équipes différentes, qui peuvent avoir des difficultés à faire converger la conception en aval. Un compromis doit par conséquent être trouvé, et ce compromis est encore aujourd’hui le résultat d’une démarche « réactive » plutôt que proactive, c’est-à-dire généralement subie, et intervenant tardivement dans le planning de développement.L’objectif principal de la thèse est de développer une méthodologie qui permette d’optimiser, à la fois vis-à-vis de l’endurance et du confort, le dimensionnement de la liaison au sol sur la base d’un signal « routier » réaliste, en s’appuyant sur les progrès du roulage numérique. Le roulage numérique est configuré comme une plateforme commune, qui suit le même processus que les validations physiques, par exemple, calculs des dommages locaux et globaux, estimations des fonctions de transfert et autres critères de confort. Par les plans d’expérience qui prennent les courbes globales des trains avant et arrière dans un espace de conception déployable, on obtient le front de Pareto après seulement plusieurs itérations. Un cas d’application montre que cette méthode est réussie à proposer la tendance générale entre les prestations avec un budget de simulation acceptable. De plus, les méthodes de datamining nous permettent de tracer l’orientation de conception de chaque groupe dans la base de données de simulation.Par ailleurs, la robustesse est aussi un sujet important pendant le développement parce que l’incertitude, qui est causée par la tolérance de fabrication ou le vieillissement de composant, peut perturber la performance conçue. Une méthode d’expansion adaptative de chaos polynomial a été appliquée pour caractériser la dispersion de sorties pendant les itérations d’optimisation. Le coût total de simulation pour une optimisation est nettement réduit par une combinaison des meta-modèles globaux et des plans d’expériences locaux.The simulation of vehicle chassis system is widely deployed at the early stage of a new car development project in order to verify if the technical specifications such as durability and comfort of current design are fulfilled. However, the numerical validations are usually carried out independently by project teams which may fail to converge the final design at downstream phase of projects. To overcome this constraint, the work of this thesis focuses on developing an early stage multi-objective optimization method. The method is able to search a set of best trade-offs between durability and comfort before the deployment of the chassis parameters. Virtual proving ground simulation is applied as a uniformed numerical validation platform, following the same process as in physical experiments, including global and local damage calculation, transfer function estimation and other comfort criteria. By realizing the design of experiments on front and rear axles’ global curves and key components in a deployable design space, the Pareto front can be obtained in first several optimization iterations. An application case on an example project shows that the method succeeds in revealing the general trends between these two chassis specifications with acceptable simulation costs. The data-mining method further demonstrates the design preferences and orientations of each group in the simulation database.Furthermore, the robustness is also an important subject in the design phase because the uncertainties resulting from manufacturing tolerances and component aging may perturb the original designs. An adaptive-sparse polynomial chaos expansion (PCE) is applied to characterize the outputs' variability in optimization iterations. The overall simulation cost in a robust optimization can be greatly reduced by combining the global meta-models and local designs of experiments

Distinguishing the Photothermal and Photoinjection Effects in Vanadium Dioxide Nanowires

Vanadium dioxide (VO₂) has drawn significant attention for its unique metal-to-insulator transition near the room temperature. The high electrical resistivity below the transition temperature (∼68 °C) is a result of the strong electron correlation with the assistance of lattice (Peierls) distortion. Theoretical calculations indicated that the strong interelectron interactions might induce intriguing optoelectronic phenomena, such as the multiple exciton generation (MEG), a process desirable for efficient optoelectronics and photovoltaics. However, the resistivity of VO₂ is quite temperature sensitive, and therefore, the light-induced conductivity in VO₂ has often been attributed to the photothermal effects. In this work, we distinguished the photothermal and photoinjection effects in VO₂ nanowires by varying the chopping frequency of the optical illumination. We found that, in our VO₂ nanowires, the relatively slow photothermal processes can be well suppressed when the chopping frequency is >2 kHz, whereas the fast photoinjection component (direct photoexcitation of charge carriers) remains constant at all chopping frequencies. By separating the photothermal and photoinjection processes, our work set the basis for further studies of carrier dynamics under optical excitations in strongly correlated materials

"High Quantum Efficiency of Band-Edge Emission from ZnO Nanowires"

External quantum efficiency (EQE) of photoluminescence as high as 20 percent from isolated ZnO nanowires were measured at room temperature. The EQE was found to be highly dependent on photoexcitation density, which underscores the importance of uniform optical excitation during the EQE measurement. An integrating sphere coupled to a microscopic imaging system was used in this work, which enabled the EQE measurement on isolated ZnO nanowires. The EQE values obtained here are significantly higher than those reported for ZnO materials in forms of bulk, thin films or powders. Additional insight on the radiative extraction factor of one-dimensional nanostructures was gained by measuring the internal quantum efficiency of individual nanowires. Such quantitative EQE measurements provide a sensitive, noninvasive method to characterize the optical properties of low-dimensional nanostructures and allow tuning of synthesis parameters for optimization of nanoscale materials

Characterization of a Bouc-Wen model-based damper model for automobile comfort simulation

International audienceRide comfort is considered as one critical focus for a chassis system. To ensure a satisfying comfort performance of a vehicle in development, a detailed damper characterization needs to be pre-defined in the early phase of project with the help of simulation results in virtual proving ground. However, the current damper model integrated in whole vehicle simulations is sometimes difficult to fit to test results due to its over-simplifications especially in low speed excitation regimes. Thus this article proposes an enhanced shock absorber model to improve simulation predictions without increasing substantially calculation costs. The parameterized model is mainly based on a Bouc-Wen model considering its capability of reproducing highly nonlinear hysteretic phenomenon. Other components such as a velocity-dependent switch have been included to reproduce the asymmetrical curve in compression and rebound phases. In order to identify the parameters, firstly a multi-objective optimization using NSGA-II algorithm has been applied based on the measurements under sinus signals. The excitations on test bench have been separated into several groups according to the forms of their force-velocity curves. The objectives are to achieve the minimum error corrections for each group. As a result, an optimum set which represents the best trade-off between the objectives is obtained and form a Pareto front. By analyzing the solutions included in this front, the best-fit intervals of parameters can be revealed. Secondly weighting factors can be decided for each objective in order to choose proper optimums from the front according to different frequency regime orientations of simulation conditions. Finally comparative examples in virtual proving ground show that the correction quality is well improved for chassis' comfort prediction using the proposed model. This example demonstrates the effectiveness of the modeling and its potential in comfort improvement with the help of design of experiments