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Search Results: 1 - 10 of 545 matches for " Lotfi Ferhat "
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Potential Role of Drebrin A, an F-Actin Binding Protein, in Reactive Synaptic Plasticity after Pilocarpine-Induced Seizures: Functional Implications in Epilepsy
Lotfi Ferhat
International Journal of Cell Biology , 2012, DOI: 10.1155/2012/474351
Abstract: Several neurological disorders characterized by cognitive deficits, including Alzheimer's disease, down syndrome, and epilepsy exhibit abnormal spine density and/or morphology. Actin-based cytoskeleton network dynamics is critical for the regulation of spine morphology and synaptic function. In this paper, I consider the functions of drebrin A in cell shaping, spine plasticity, and synaptic function. Developmentally regulated brain protein (drebrin A) is one of the most abundant neuron-specific binding proteins of F-actin and its expression is increased in parallel with synapse formation. Drebrin A is particularly concentrated in dendritic spines receiving excitatory inputs. Our recent findings point to a critical role of DA in dendritic spine structural integrity and stabilization, likely via regulation of actin cytoskeleton dynamics, and glutamatergic synaptic function that underlies the development of spontaneous recurrent seizures in pilocarpine-treated animals. Further research into this area may provide useful insights into the pathology of status epilepticus and epileptogenic mechanisms and ultimately may provide the basis for future treatment options. 1. Introduction The human brain is composed by hundred billion neurons interconnected in order to form functional neuronal networks that control higher brain functions, such as learning, thoughts, emotions, and memory throughout life. The communication between neurons within neuronal networks is mediated via synapses. Tight control mechanisms of the formation, growth, and connectivity of synapses are crucial for accurate neural network activity and normal brain function. For example, the development, remodeling, and elimination of excitatory synapses on dendritic spines represent ways of refining the microcircuitry in the brain. Thus, when processes involved in structural synapses and/or synaptic function go awry, either during normal aging or in disease, dysfunction of the organism occurs. 2. Dendritic Spines and Functions Dendritic spines are tiny protrusions from the dendritic tree that serve as the postsynaptic component for the vast majority of excitatory synapses in the central nervous system [1–4]. These protrusions are found on most excitatory and some inhibitory neurons [2, 3, 5, 6]. The dendritic spine consists of a bulbous head connected to the dendritic shaft by a narrow neck [1, 7]. The narrow neck of the spine forms a spatially isolated compartment where molecular signals can rise and drop without diffusing to neighboring spines along the parent dendrite, thus allowing the isolation
The Effects of Dimension Ratio and Horizon Length in the Micropolar Peridynamic Model  [PDF]
Y. Ferhat, I. Ozkol
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.36071
Abstract: The aim of this study is to investigate the effects of horizon selection on the elastic behaviour of plate type structures in the micropolar peridynamic theory. Plates with various lengths and widths have been investi-gated using micropolar peridynamic model for different horizon selections. The mathematical model of plates has been provided applying the micropolar peridynamic theory and solution of this model has been obtained by finite element methods. The displacement fields have been computed for the different horizons and dimension ratios of plates. To compute the displacement field a program code has been developed by using the software package MATHEMATICA. The results obtained have been compared with the analytical solution of the classical elasticity theory and with the solution of displacement based finite element methods. For displacement based finite element method solution the software package ANSYS has been used. Ac-cording to results it has been observed that the displacement fields of the plates are strongly affected by ho-rizon selection. Therefore a question raises that which horizon length should be used with the problem in hand or is there any method to find the appropriate/best horizon length.
Simulation Topographical Surfaces Geographical and Geological Using Differential Geometry  [PDF]
Mohammedi Ferhat, Bensaada Said
International Journal of Geosciences (IJG) , 2011, DOI: 10.4236/ijg.2011.24070
Abstract: By applying differential geometry to analogue models developed such a model is calculated for the geometrical shape. Dip measurements are critical data for geologists, and in particular for structural studies. They enable quantifying geologic features observed across the surface in order to model the sub-surface. Dip measurements are provided by direct or indirect sources: geological maps, fieldwork data, Digital Elevation Model (DEM). This quantification then allows for comparison of such models to measured field data and supplants the use interferometry Radar describes and compares 3-D deformations. This example supplements and is based on the material found in L.S.S.I.T. Theory as well as some of the experimental results with the new method are delineated.
Influence of Residual Basal Area on Longleaf Pine (Pinus palustris Mill.) First Year Germination and Establishment under Selection Silviculture  [PDF]
Ferhat Kara, Edward F. Loewenstein
Open Journal of Forestry (OJF) , 2015, DOI: 10.4236/ojf.2015.51002
Abstract: Even-aged silvicultural methods have been successfully used to manage longleaf pine (Pinus palustris Mill.) forests for wood production; however, successful use of uneven-aged methods to manage this ecosystem is less well documented. In this study, the effects of varying levels of residual basal area (RBA) (9.2, 13.8, and 18.4 m2·ha-1) on longleaf pine germination and establishment under selection silviculture marked using the Proportional-B method were observed. In addition to RBA, photosynthetically active radiation (PAR) was measured, and the relationships between light penetration, germination, and growth were examined. The study found an inverse relationship between RBA and the number of germinants, but the mortality of germinants was not influenced by RBA. PAR also had a significant positive effect on germination, but, did not affect mortality of germinants. In addition, RBA and PAR had no effect on mortality or growth of planted seedlings. Continued monitoring of seedling recruitment into the stand will be required to determine the efficacy of the system. However, nothing in the first year data suggests that this approach will not be successful in sustaining an uneven-aged stand.
RPE (Résonance Paramagnétique Electronique): Applications biomédicales
Mohammed FERHAT
Technologies de Laboratoire , 2008,
Abstract: La Résonance Paramagnétique Electronique (RPE) est un puissant moyen d'investigation des systèmes paramagnétiques. Ces systèmes correspondent à des matrices se dotant d’électrons célibataires tels que les complexes de métaux de transition, les sels, les radicaux libres, … etc. Les renseignements fournis par le RFE concernent l’identification, la structure électronique et géométrique des systèmes étudiés, leur comportement dynamique, les mécanismes de réaction, …etc. De plus, la RPE, vue sa grande sensibilité, s'applique aussi aux systèmes diamagnétiques moyennant des radicaux libres qui peuvent être utilisés comme sondes (techniques de marquage et de piégeage de spin) : études de solvatation, de mécanismes de transferts dans les systèmes biologiques, études conformationnelles, …etc. C’est pourquoi la RPE est devenue ces dernières années un outil d’étude puissant pour la biologie, la pharmacologie, en biomédicale, …etc. Comparée à la RMN, la RPE est une technique beaucoup plus sensible (facteur 1000-2000), mais l'interprétation des spectres est plus délicate, notamment à cause des effets d'anisotropie et à cause au couplage entre les moments de spin électronique et orbital. Les mesures quantitatives sont également moins faciles à effectuer avec la RPE qu'avec la RMN.
From “Ghetto” to “Interculturality”: Euro-Turkish Experiences in Germany and France
Ferhat Kentel
Revista CIDOB d'Afers Internacionals , 2006,
Abstract: This article is based on a research project carried out among Turkish immigrants in Germany and France. It deals with showing the multiplicity of identity formation, depending on generations, but, above all, the new experiences of the “Turkish communities”, namely,in a range from being self-enclosed to total assimilation in the case of “citizen of the French Republic” and “German culturalism”. In this range, what enriches the debate on identities and “the issue of integration” is, above all, these identities in movement which, up until now, have been perceived as indices of the inability of the actors in situ. This article attempts to demonstrate that, far from being a question of inability, it is a matter of “new tactics of superseding” the modernist structures, unable to satisfy the existenceof the diaspora. Thus, while the individuals in the immigrant communities enter into cultural negotiation with the society and play on the borders, in a trans-national space, they call into question modernist dichotomies and national borders and symbols. Finally,“intersubjectivity” and “interculturality”, in which these individuals fulfil themselves, bind the dissociated parts of the human being and social life and prepare the social bases of a new citizenship.
Nationalist Reconstructions in the Face of the Disappearance of Borders
Ferhat Kentel
Revista CIDOB d'Afers Internacionals , 2008,
Abstract: Together with the conflictive negotiation abouth the definition and the feeling of nation, on a strategic level, the repercussions of globalisation (and especially the negotiations with the European Union) are complicating the border issue and, as a consequence, the issue of unity (which is “always in danger”, according to the nationalist-Kemalist elites). The nationalist discourse is consumed on a popular level but, rather than simple consumption or pure strategic production, it is constituted as the production of different nationalisms in the tactics of everyday life. In this way, this article tackles the subject of the new nationalist productions, examining more deeply the tactics that range from survival to subversion or new religious rites in a situation of uncertainties and ambivalences brought about by globalisation, by a new encounter with the West and by the disappearance of borders.
Ferhat Khenak
Advances in Mathematical and Computational Methods , 2012, DOI: 10.5729
Abstract: The technicality is no longer an obstacle; the issue of any environment of E-Learning (before) or V-Learning (now) is the production then the protection (in terms of security and confidentiality) of the content flowing through it. As part of our national policy of Visual Informatics For Education (VIFE), specifically for our Algerian V-Learning Network (AVN), which is a device of distributed interactive learning spread over all our vast territory according to a new concept based on the principle of the Online Video Learning via Internet and/or by Satellite; we have developed an encryption method enabling a certain security of copyrights. This paper discusses this method and presents its SecuRights system based on a distributed random algorithm.
Turkish Studies , 2010,
Abstract: In this study we will deal with passive structures without passive morphology in Turkic dialects. As is known there are two allomorfs using for transforming an active verb into a passive one in Turkic language. These mostly are –l- and –n-. On the other hand there are some typologies which carry passive voice without an active morphology like Turkic type participle constructions. In order to examine this kind of typology we will look at the deep structure and surface structure of Turkic dialects and make use of the rules called empty categories and government and binding principles. Bu al mada Türk dilinin yüklemi edilginle tirici bi imbirimleri olan –l- ve –n- olmadan da edilgen at olu turabildi ini g stermeye al aca z. zellikle s fat-fiilli yap larda ortaya kan etken morfolojili edilgen at lar Türk dilinin hemen bütün evrelerinde g rülebilmektedir. Etken yap l edilgen at tipolojisini ortaya koymak i in üretken D nü ümlü Dilbilgisi Kuram 'n n dilin iki düzlemi olarak tan mlad derin yap ve yüzey yap ba lant s na dikkat ekece iz. Buna ilave olarak bo luk kuram ve y netim ba lama ilkesinden de faydalanaca z.
Turkish Studies , 2011,
Abstract: Modernism in Turkish literature begins by the mediation of journal. Most of new literary types attained to our literature owe their existances and developments to journal. Yusuf Kamil Pa a brings in first translation novel to Turkish by means of consecutive narrative for a newspaper. After that novels are published by means of consecutive narrative in Tanzimat era. Ahmet Mithat Efendi is both journalist and novelist. Ahmet Mithat Efendi who seeks compromise between journal and novel handles the contribution of both type to each other in Esrar- Cinayat novel. In the novel, he discusses the cooperation of a civil servant who encounters pressure and a true journalist for the criminals to be catched and handed over to the justice and for the relief of the conscience of public. The novelist that makes journal and journalist the most important component for the solution of events gives a lot of information about the journalism in Tanzimat era, as well. On this occasion, the affairs like journalism, typography, Newsprinting Regulation (Matbuat Nizamnamesi), freedom of notion newspaper- government relation and censorship become the most important matters that emphasize on in the novel. Türk edebiyat nda modernle me gazete arac l yla ba lar. Edebiyat m za yeni kazand r lan pek ok tür varl n ve geli imini gazeteye bor ludur. Yusuf Kamil Pa a, gazetede tefrika ettirmek suretiyle ilk eviri roman Türk eye kazand r r. Bundan sonra Tanzimat d neminde roman, gazetelerde tefrika yoluyla yay mlan r. Ahmet Mithat Efendi hem gazeteci hem de romanc d r. Gazete ve roman aras nda uzla ma arayan Ahmet Mithat Efendi, Esrar- Cinayat roman nda bu iki türün birbirine olan katk s n ele al r. Romanda do rular n yan nda yer alan bir gazeteci ve bask yla kar kar ya kalan bir devlet memurunun su lular n yakalan p adalete teslim edilmesi ve kamuoyunun vicdan n n rahatlat lmas i in yapt klar i birli i ele al nmaktad r. Gazete ve gazeteciyi vaka zümünde en nemli unsur haline getiren romanc , Tanzimat d nemi gazetecili i hakk nda bize pek ok bilgi de sa lamaktad r. Bu vesileyle gazetecilik, matbaac l k, Matbuat Nizamnamesi, ifade zgürlü ü, gazete-iktidar ili kisi ve sansür gibi meseleler romanda üzerinde en ok durulan konular haline gelir.
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