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Search Results: 1 - 10 of 144183 matches for " B. Chebaro "
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Video Macrosegmentation Using Automatic Analysis of Similarity Matrices
S. Haidar,B. Chebaro,B. Haidar
Information Technology Journal , 2010,
Abstract: In the present study, we propose an automatic method for segmenting video material using the comparison matrix. Without a priori information, neither any training phase, the similarity matrices are filtered then regional minimums and maximums are extracted over the line and column projections. Pseudo-homogeneous areas are identified between each pair of regional minimums. The pseudo-homogeneous areas in the resulting matrix are thus the macro-segment video records in question. We experiment our method over a database of short video commercials to illustrate the potential of our approach. An overall evaluation is finally established and given.
Compositional Testing For FSM-Based Models
Bilal Kanso,Omar Chebaro
Computer Science , 2014,
Abstract: The contribution of this paper is threefold: first, it defines a framework for modelling component-based systems, as well as a formalization of integration rules to combine their behavior. This is based on finite state machines (FSM). Second, it studies compositional conformance testing i.e. checking whether an implementation made of conforming components combined with integration operators is conform to its specification. Third, it shows the correctness of the global system can be obtained by testing the components involved into it towards the projection of the global specification on the specifications of the components. This result is useful to build adequate test purposes for testing components taking into account the system where they are plugged in.
Crucial role of non-specific interactions in amyloid nucleation
An?ela ?ari?,Yassmine C. Chebaro,Tuomas P. J. Knowles,Daan Frenkel
Quantitative Biology , 2014, DOI: 10.1073/pnas.1410159111
Abstract: Protein oligomers have been implicated as toxic agents in a wide range of amyloid-related diseases. Yet it has remained unsolved whether the oligomers are a necessary step in the formation of amyloid fibrils, or just a dangerous by-product. Analogously, it has not been resolved if the amyloid nucleation process is a classical one-step nucleation process, or a two-step process involving pre-nucleation clusters. We use coarse-grained computer simulations to study the effect of non-specific attractions between peptides on the primary nucleation process underlying amyloid fibrillization. We find that for peptides that do not attract, the classical one-step nucleation mechanism is possible, but only at non-physiologically high peptide concentrations. At low peptide concentrations, which mimic the physiologically relevant regime, attractive inter-peptide interactions are essential for fibril formation. Nucleation then inevitably takes place through a two-step mechanism involving prefibrillar oligomers. We show that oligomers not only help peptides meet each other, but create an environment that facilitates the conversion of monomers into the $\beta$-sheet rich form characteristic of fibrils. Nucleation typically does not proceed via the most prevalent oligomers, but via an oligomer size that is only observed in rare fluctuations, which is why such aggregates might be hard to capture experimentally. Finally, we find that the nucleation of amyloid fibrils cannot be described by classical nucleation theory: in the two-step mechanism the critical nucleus size increases both with an increase in concentration and in the inter-peptide interactions, in direct contrast with predictions from classical nucleation theory.
Phosphorylation of the Retinoic Acid Receptor Alpha Induces a Mechanical Allosteric Regulation and Changes in Internal Dynamics
Yassmine Chebaro,Is Amal,Natacha Rochel,Cécile Rochette-Egly,Roland H. Stote ,Annick Dejaegere
PLOS Computational Biology , 2013, DOI: 10.1371/journal.pcbi.1003012
Abstract: Nuclear receptor proteins constitute a superfamily of proteins that function as ligand dependent transcription factors. They are implicated in the transcriptional cascades underlying many physiological phenomena, such as embryogenesis, cell growth and differentiation, and apoptosis, making them one of the major signal transduction paradigms in metazoans. Regulation of these receptors occurs through the binding of hormones, and in the case of the retinoic acid receptor (RAR), through the binding of retinoic acid (RA). In addition to this canonical scenario of RAR activity, recent discoveries have shown that RAR regulation also occurs as a result of phosphorylation. In fact, RA induces non-genomic effects, such as the activation of kinase signaling pathways, resulting in the phosphorylation of several targets including RARs themselves. In the case of RARα, phosphorylation of Ser369 located in loop L9–10 of the ligand-binding domain leads to an increase in the affinity for the protein cyclin H, which is part of the Cdk-activating kinase complex of the general transcription factor TFIIH. The cyclin H binding site in RARα is situated more than 40 ? from the phosphorylated serine. Using molecular dynamics simulations of the unphosphorylated and phosphorylated forms of the receptor RARα, we analyzed the structural implications of receptor phosphorylation, which led to the identification of a structural mechanism for the allosteric coupling between the two remote sites of interest. The results show that phosphorylation leads to a reorganization of a local salt bridge network, which induces changes in helix extension and orientation that affects the cyclin H binding site. This results in changes in conformation and flexibility of the latter. The high conservation of the residues implicated in this signal transduction suggests a mechanism that could be applied to other nuclear receptor proteins.
The Asymmetric Binding of PGC-1α to the ERRα and ERRγ Nuclear Receptor Homodimers Involves a Similar Recognition Mechanism
Maria Takacs, Maxim V. Petoukhov, R. Andrew Atkinson, Pierre Roblin, Fran?ois-Xavier Ogi, Borries Demeler, Noelle Potier, Yassmine Chebaro, Annick Dejaegere, Dmitri I. Svergun, Dino Moras, Isabelle M. L. Billas
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0067810
Abstract: Background PGC-1α is a crucial regulator of cellular metabolism and energy homeostasis that functionally acts together with the estrogen-related receptors (ERRα and ERRγ) in the regulation of mitochondrial and metabolic gene networks. Dimerization of the ERRs is a pre-requisite for interactions with PGC-1α and other coactivators, eventually leading to transactivation. It was suggested recently (Devarakonda et al) that PGC-1α binds in a strikingly different manner to ERRγ ligand-binding domains (LBDs) compared to its mode of binding to ERRα and other nuclear receptors (NRs), where it interacts directly with the two ERRγ homodimer subunits. Methods/Principal Findings Here, we show that PGC-1α receptor interacting domain (RID) binds in an almost identical manner to ERRα and ERRγ homodimers. Microscale thermophoresis demonstrated that the interactions between PGC-1α RID and ERR LBDs involve a single receptor subunit through high-affinity, ERR-specific L3 and low-affinity L2 interactions. NMR studies further defined the limits of PGC-1α RID that interacts with ERRs. Consistent with these findings, the solution structures of PGC-1α/ERRα LBDs and PGC-1α/ERRγ LBDs complexes share an identical architecture with an asymmetric binding of PGC-1α to homodimeric ERR. Conclusions/Significance These studies provide the molecular determinants for the specificity of interactions between PGC-1α and the ERRs, whereby negative cooperativity prevails in the binding of the coactivators to these receptors. Our work indicates that allosteric regulation may be a general mechanism controlling the binding of the coactivators to homodimers.
The Mélange of Innovation and Tradition in Maltese Law: The Essence of the Maltese Mix?
B Andò
Potchefstroom Electronic Law Journal/Potchefstroomse Elektroniese Regsblad , 2012,
Abstract: Aim of this paper is to provide valuable insights into the Maltese legal system with a special focus on private law. The assumption is that this legal system is the byproduct of the "mixing" of innovation and tradition, resulting from the interaction of English law and continental law. A major role in the development of the system is played by courts. Some examples (moral damages and pre-contractual liability) are considered which highlight the importance of the function displayed by Maltese judges. KEYWORDS: Tradition; English law; continental law; hybridity; mixed legal systems; Maltese courts; moral damages; pre-contractual liability; lacunae
PROBLEMS OF FLIGHT PERSONNEL PREPARATION FOR MODERN AIRCRAFTS П ДГОТОВКА ЛЬОТНОГО СКЛАДУ НА СУЧАСН ПОВ ТРЯН СУДНА П ДГОТОВКА ЛЬОТНОГО СКЛАДУ НА СУЧАСН ПОВ ТРЯН СУДНА
B. Харченко,О. Ал?кс??в,Д. Бабейчук,М. Повознюк
Proceedings of National Aviation University , 2011,
Abstract: At present, the problem who can and who should solve the question concerning the preparationand recurrent training of pilots of Ukrainian civil aviation is not solved. The necessity of updatingof aircraft’s park in aviation branch and aircraft operation, which was ripened 10 years ago,demands a corresponding infrastructure. It is necessary to understand, that the pilots ready toperform the flights on modern aircrafts, will not appear by themselves, therefore the real actions onmodernization of existing system of aircrew and the aviation personnel preparation as a whole arerequired. Main objective of this work is the determination of the basic components concerning thesolving of the problematic questions on preparation of aircrew on modern types of aircrafts. Duringthe problem analysis it was specified that the present development of system of aircrew preparationin Ukraine is not perfect, and does not correspond the ICAO and EU requirements, therefore needsan immediate intervention at the highest State level. Trainings are not complex, as do not containthe elements of selection of aircrew members cooperation. Programs of recurrent training ofaircrew, courses of pilots training flight preparation were not reconsidered for many years Розглянуто проблему п дготовки п лот в цив льно ав ац Уккра ни, яка на сьогодн нев дпов да вимогам ICAO та С. Визначено основн складов п дготовки льотного складу насучасн пов трян судна.Ключов слова: аеронав гац йне обслуговування, керована множина, керован об’ кти,рад олокац йне та рад онав гац йне забезпечення польот в, системи керування пов трянимрухом. Розглянуто проблему п дготовки п лот в цив льно ав ац Уккра ни, яка на сьогодн нев дпов да вимогам ICAO та С. Визначено основн складов п дготовки льотного складу насучасн пов трян судна.
METHOD OF SYNTHESIS OF PROBLEM QUALITY OF THE COMPLEX NONLINEAR DYNAMIC SYSTEM CONTROL МЕТОД ГАРАНТОВАНОГО ОЦ НЮВАННЯ ОБЛАСТ ПОВН СТЮКЕРОВАНОГО СТАНУ СКЛАДНО НЕЛ Н ЙНО ДИНАМ ЧНО СИСТЕМИ МЕТОД ГАРАНТОВАНОГО ОЦ НЮВАННЯ ОБЛАСТ ПОВН СТЮ КЕРОВАНОГО СТАНУ СКЛАДНО НЕЛ Н ЙНО ДИНАМ ЧНО СИСТЕМИ
С. Павлова,B. Павлов,В. Чеп?женко
Proceedings of National Aviation University , 2011,
Abstract: Substantially nonlinear objects function at limitations of arbitrary kind. These limitations are not necessarily convex areas. For such objects the construction of area of the fully the fully-controlled state area is a serious problem. In the article it has been suggested to replace this task the task of the fully-controlled state area estimation from within. The secure estimation method of the fully-controlled state area has been developed for this purpose. Other dynamic system has been used as a tester (measure) of the fully-controlled state area. Construction and estimation of controllability and accessibility area of this dynamic system well methodically validate and deserved researchers confession. The descriptions concordance requirements of this new object with properties of initial object must be executed and provide property of immersion of new object in an initial object. Possibility is thus opened on the the fully-controlled state area of new object to define the the fully-controlled state area of the initial system На основ процедури мерсування м рних об’ кт в у вих дний об’ кт розроблено методгарантованого оц нювання област повн стю керованого стану.On the basis of procedure of immersion of the measuring objects in an initial object the secureestimation method of the fully controlled state area has been developed.На основе процедуры иммерсирования мерных объектов в исходный объект разработанметод гарантированного оценивания области полностью управляемого состояния. Показано, що для стотно нел н йних об’ кт в, що функц онують в умовах наявност обме-жень дов льного виду, як не обов’язково опуклими областями, побудова област повн стюкерованого стану проблематична. Запропоновано зам нити це завдання оц нюванням област повн стю керованого стану зсередини. Для цього розроблено метод гарантовано оц нюванняобласт повн стю керованого стану. Як вим рника (м ра) област повн стю керованого станувикористана нша динам чна система, п
THE SYSTEM METHOD OF IMMERSION AND VIRTUALIZATION OF MEASURED SYSTEMS IN REAL PROCESS СИСТЕМНИЙ МЕТОД МЕРСУВАННЯ ТА В РТУАЛ ЗАЦ М РНИХ СИСТЕМ У РЕАЛЬНИЙ ПРОЦЕС СИСТЕМНИЙ МЕТОД МЕРСУВАННЯ ТА В РТУАЛ ЗАЦ М РНИХ СИСТЕМ У РЕАЛЬНИЙ ПРОЦЕС
С. Павлова,B. Павлов,В. Чеп?женко
Proceedings of National Aviation University , 2012,
Abstract: The system method of immersion and virtualization of measured systems in real process is offered. The method works out problem of virtual systems formation and sets conditions at which virtual object to become measuring system for of completely controlled condition field. Here the system of interactively oriented rectangular n-dimensional parallelepipeds is used as measuring system. Imbeddedness of measuring system in real process is understood as process of approximation of a real system controlled condition cone by system of rectangular n-dimensional parallelepipeds. Запропоновано системний метод мерсування та в ртуал зац м рних систем вреальний динам чний процес як процедуру утворення вкладених в ртуальних систем,визначених на погоджено-ор нтованих прямокутних п-вим рних паралелеп педах.Ключов слова: в ртуал зац я, в ртуальний м рний процес, мерс я, складна нел н йнадинам чна система. Запропоновано системний метод мерсування та в ртуал зац м рних систем в реальний динам чний процес як процедуру утворення вкладених в ртуальних систем, визначених на погоджено-ор нтованих прямокутних п-вим рних паралелеп педах.
THE MéLANGE OF INNOVATION AND TRADITION IN MALTESE LAW: THE ESSENCE OF THE MALTESE MIX?
B Andò
Potchefstroom Electronic Law Journal/Potchefstroomse Elektroniese Regsblad , 2012,
Abstract: Aim of this paper is to provide valuable insights into the Maltese legal system with a special focus on private law. The assumption is that this legal system is the by-product of the "mixing" of innovation and tradition, resulting from the interaction of English law and continental law. A major role in the development of the system is played by courts. Some examples (moral damages and pre-contractual liability) are considered which highlight the importance of the function displayed by Maltese judges.
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