Courbure et Polygone de Newton

2000 Mathematics Subject Classification: 26E35, 14H05, 14H20.The object of this article relates to the study of the complex algebraic curves by using the concept of envelope convex. One proposes to characterize the points of a holomorphic complex curve (C) and to associate a metric invariant to them ( generalized curvature), by using the equations of the various segments constituting the polygon of Newton associated with (C)

Archetypal Analysis: Mining Weather and Climate Extremes

Conventional analysis methods in weather and climate science (e.g., EOF analysis) exhibit a number of drawbacks including scaling and mixing. These methods focus mostly on the bulk of the probability distribution of the system in state space and overlook its tail. This paper explores a different method, the archetypal analysis (AA), which focuses precisely on the extremes. AA seeks to approximate the convex hull of the data in state space by finding “corners” that represent “pure” types or archetypes through computing mixture weight matrices. The method is quite new in climate science, although it has been around for about two decades in pattern recognition. It encompasses, in particular, the virtues of EOFs and clustering. The method is presented along with a new manifold-based optimization algorithm that optimizes for the weights simultaneously, unlike the conventional multistep algorithm based on the alternating constrained least squares. The paper discusses the numerical solution and then applies it to the monthly sea surface temperature (SST) from HadISST and to the Asian summer monsoon (ASM) using sea level pressure (SLP) from ERA-40 over the Asian monsoon region. The application to SST reveals, in particular, three archetypes, namely, El Niño, La Niña, and a third pattern representing the western boundary currents. The latter archetype shows a particular trend in the last few decades. The application to the ASM SLP anomalies yields archetypes that are consistent with the ASM regimes found in the literature. Merits and weaknesses of the method along with possible future development are also discussed

Impedance spectroscopy, electrical relaxation and Ac conductivity studies of organic-inorganic hybrid compound: NH3(C6H4)2NH3HgCl4

Organic–inorganic hybrid sample NH3(C6H4)2NH3HgCl4 was characterized by differential scanning calorimetry (DSC), TGA analysis and electrical impedance spectroscopy. DSC studies indicated the presence of a one-phase transition at 391 K. As for the ac conductivity of the compound NH3(C6H4)2NH3HgCl4, it has been measured in the temperature range of 358 - 413K and the frequency range of 209 Hz–5 MHz. Concerning the Z’ and Z’’ versus frequency plots, they were well-fitted to an equivalent circuit model. The equivalent circuit is composed of a series of combination of two parallel (R//CPE) circuits. Besides, the frequency dependence of the conductivity was interpreted in terms of Jonscher's law σ(ω) = σdc +A ωn.  As regards the conductivity, it follows the Arrhenius relation. The variation of the value of the conductivity with temperatures confirmed the availability of the phase transition at 391K detected by DSC and electrical measurements

Bloc de la ligne blanche au secours de la chirurgie herniaire

Une hernie de la ligne blanche est une hernie située sur la ligne médiane entre les muscles grands droits de l'abdomen. Le diagnostic repose généralement sur un examen clinique. Plus rarement, il nécessite une échographie, voire un scanner.L'intervention pour soigner une hernie de la ligne blanche est le plus souvent réalisée en ambulatoire et sous anesthésie générale. Elle est réalisée par laparotomie, laparoscopie ou assistance robotique. Le choix de la technique dépend de l'épaisseur du tissu, de la taille de la hernie et de la présence d'interventions abdominales antérieures. L'intervention consiste à remettre l'intestin dans sa position initiale et à refermer le trou par lequel il est passé. Si le trou de la hernie est supérieur à 1 cm, un treillis est placé pour renforcer l'espace fermé par la chirurgie et prévenir les récidives.La diversité des pathologies et des antécédents des patients a nécessité une diversité de techniques anesthésiques plus adaptées d'où l'anesthésie locorégionale et lesblocs de la paroi abdominal

Neobična pristunost juvenilnih primjeraka vrste Synagrops japonicus u jugozapadnom Mediteranu

This paper reports additional records of the Indo-Pacific fish Synagrops japonicus (Doderlein, 1884) in Western Mediterranean. Twenty juveniles of this species ranging from 4 to 4.8 cm (TL) were caught in Annaba Bay, Algeria, using beach seine, in Summer of 2011 (9 specimens, 4 ≤ TL ≤ 4.6 cm) and 2012 (11 specimens, 4.2 ≤ TL ≤ 4.8 cm). Some hypotheses on the origin of this unusual presence are discussed.U ovom radu se navode dodatni nalazi vrste Synagrops japonicus (Doderlein, 1884) u zapadnom Mediteranu. Uhvaćeno je dvadeset juvenilnih primjeraka ove vrste u rasponu od 4 do 4,8 cm (TL) u Annaba zaljevu, Alžir, pomoću obalne mreže potegače, u ljeto 2011. godine (9 primjeraka, 4 ≤ TL ≤ 4,6 cm) i 2012. (11 primjeraka, 4.2 ≤ TL ≤ 4,8 cm). U radu su iznesene neke hipoteze o podrijetlu ove neobične prisutnosti

Response of sesame seedlings to different concentrations of humic acids or calcium nitrate at germination and early growth

This study was conducted in order to evaluate the response of sesame seeds (Sesamum indicum L.) to organic or mineral fertilization. The effects of two fertilizers, which were calcium nitrate and humic acids were studied separately at germination and early seedlings growth. Different concentrations of humic acids (HA0: 0, HA1: 500, HA2: 1000 and HA3: 2000 mg L–1) or calcium nitrate (CaN0: 0, CaN1: 50, CaN2: 100 and CaN3: 200 mg L–1) were applied distinctly to the growth media. The experimental design was accomplished in a completely randomized block design with three replications. Germination measurements, seedlings length, fresh seedling weight, total chlorophylls and carotenoids, total soluble proteins and sugars were determined. Results showed that humic acids applied at 1000 mg L-1 or calcium nitrate applied at 100 mg L-1 reduced the mean germination time (3.5 and 3.61 days) and had the highest germination index (GI) and the highest coefficient of velocity (CV). The longest seedling was obtained at the concentrations HA2 and CaN2 (+22%). Total chlorophyll and carotenoids were significantly higher in seedlings receiving the HA2 and CaN2 and these treatments increased total soluble proteins content by 32%. Higher concentrations of humic acids or calcium nitrate HA3 and CaN3 delayed germination and enhanced proline and total soluble sugars, respectively, by 42% and 46%, compared to control. These preliminary results indicated that the use of fertilizers should be optimized and they can be transformed at high level to an abiotic stress menacing plant productivity. On the other hand, suitable concentrations of fertilizers can be used in the future as a remedy to improve growth under abiotic stress

Evaluation by a finite element method of the flexibility factor and fixity degree for the base plate connections commonly used

Using finite element approach, we have determined the flexibility factor and fixity degree of connections between a steel column and a reinforced concrete foundation. Two types of connections are studied. The first one consists of a base plate welded to the end of column and attached to the reinforced concrete foundation by two anchor bolts. These bolts are placed on the major axis of the I-shaped section used as column. In the second configuration, the connection comprises a base plate and four anchor bolts placed out side the flanges of the I-shaped section. Two types of loadings are used, first connections were subjected to shear force and a bending moment, in the second case, the connections were subjected to shear force, a bending moment and an axial compressive force. To take into account the real behavior of these connections, an approach treating of the contact- friction problem between the base plate and the concrete foundation is retained. The method of approach is based on a unilateral contact law in which a Coulomb friction is added. The numerical resolution is ensured by the refined Lagrangian method. The moments-rotations curves, the flexibility factor according to the distance of the top of base plate curves are drawn. The fixity degrees of the connections are determinate and their influence on the loads and deformations are evaluated.Із використанням скінченноелементного підходу визначено значення коефіцієнта гнучкості та степеня стійкості вузлів з ’єднання стальної балки із залізобетонною основою. Досліджено два типи з ’єднань: у першому стальна опорна пластина з привареною до неї вертикальною балкою кріпиться до залізобетонної основи двома анкерними болтами, які знаходяться на осі симетрії двотаврової балки, у другому - чотирма болтами. Навантаження прийнято двох типів: перше з ’єднання зазнавало дії перерізувальної сили і згинального моменту, друге - перерізувальної сили, згинального моменту та осьової сили стиску. Реальну поведінку цих з ’єднань описували за допомогою підходу, який враховує умови контакту та тертя між опорною плитою і залізобетонною основою. Підхід базується на однобічності залежності для контактної задачі з кулонівським тертям. Для підвищення точності числових розрахунків застосовано модифікований метод Лагранжа. Отримано діаграми в координатах момент-кутове переміщення та коефіцієнт гнуч- кості-відстань від вершини вертикальної балки до опорної плити. Визначено вплив степеня стійкості з’єднань на допустимі навантаження і деформації.С использованием конечноэлементного подхода определены значения коэффициента гибкости и степени устойчивости узлов соединения стальной балки с железобетонным основанием. Исследуются два типа соединений: в первом стальная опорная пластина с приваренной к ней вертикальной балкой крепится к железобетонному основанию двумя анкерными болтами, которые расположены на оси симметрии двутавровой балки, во втором - четырьмя болтами. Задавались два типа нагружения: первое соединение подвергалось действию перерезывающей силы и изгибающего момента, второе - перерезывающей силы, изгибающего момента и осевой силы сжатия. Для описания реального поведения этих соединений использовался подход, учитывающий условия контакта и трения между опорной балкой и железобетонным основанием. Подход основан на односторонней зависимости для контактной задачи с кулоновским трением. Для повышения точности численных расчетов используется модифицированный метод Лагранжа. Получены диаграммы в координатах момент-угловое перемещение и коэффициент гибкости-расстояние от вершины вертикальной балки до опорной плиты. Определено влияние степени устойчивости соединений на допустимые нагрузки и деформации

Impeller optimization in crossflow hydraulic turbines

Crossflow turbines represent a valuable choice for energy recovery in aqueducts, due to their constructive simplicity and good efficiency under variable head jump conditions. Several experimental and numerical studies concerning the optimal design of crossflow hydraulic turbines have already been proposed, but all of them assume that structural safety is fully compatible with the sought after geometry. We show first, with reference to a specific study case, that the geometry of the most efficient impeller would lead shortly, using blades with a traditional circular profile made with standard material, to their mechanical failure. A methodology for fully coupled fluid dynamic and mechanical optimization of the blade cross-section is then proposed. The methodology assumes a linear variation of the curvature of the blade external surface, along with an iterative use of two-dimensional (2D) computational fluid dynamic (CFD) and 3D structural finite element method (FEM) simulations. The proposed methodology was applied to the design of a power recovery system (PRS) turbine already installed in an operating water transport network and was finally validated with a fully 3D CFD simulation coupled with a 3D FEM structural analysis of the entire impeller

α5β1-Integrin promotes tension-dependent mammary epithelial cell invasion by engaging the fibronectin synergy site.

Tumors are fibrotic and characterized by abundant, remodeled, and cross-linked collagen that stiffens the extracellular matrix stroma. The stiffened collagenous stroma fosters malignant transformation of the tissue by increasing tumor cell tension to promote focal adhesion formation and potentiate growth factor receptor signaling through kinase. Importantly, collagen cross-linking requires fibronectin (FN). Fibrotic tumors contain abundant FN, and tumor cells frequently up-regulate the FN receptor α5β1 integrin. Using transgenic and xenograft models and tunable two- and three-dimensional substrates, we show that FN-bound α5β1 integrin promotes tension-dependent malignant transformation through engagement of the synergy site that enhances integrin adhesion force. We determined that ligation of the synergy site of FN permits tumor cells to engage a zyxin-stabilized, vinculin-linked scaffold that facilitates nucleation of phosphatidylinositol (3,4,5)-triphosphate at the plasma membrane to enhance phosphoinositide 3-kinase (PI3K)-dependent tumor cell invasion. The data explain why rigid collagen fibrils potentiate PI3K activation to promote malignancy and offer a perspective regarding the consistent up-regulation of α5β1 integrin and FN in many tumors and their correlation with cancer aggression