Development of performance measurement model for oil operations: A study of Libyan oil companies

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonPetroleum practices involve high capital infrastructure together with complex production process for which performance measures can support examination of production within the petroleum industrial phases. The focus of this research is the performance measurement of existing and future petroleum operations. This study aims to develop a model to evaluate the employment of performance measurement in state-owned as well as private petroleum firms within the Libyan context to recognize existing activities as well as their influence on performance management. This research highlights some resources of firms including asset management and partnerships that influence their operations to acquire and multiply knowledge and technology, leading to more successful processes and better performance. This research aims to provide a model that comprises factors that may influence Libyan firms‟ performance including exploration, drilling, production, reserves, technology upgrades and health, safety and environment. This research employed a mixed method of quantitative and qualitative approaches with a dominant quantitative method, correlation and regression tests were conducted .A questionnaire survey was conducted in 17 Libyan oil firms including public, joint venture and private firms, 85 valid questionnaires were analyzed by using SPSS (V.18). The findings of this research revealed that firms may enhance their ability to acquire, assimilate, and exploit knowledge and technology by the utilization of asset management as well as partners. Further, factors including exploration, production, reserves, technology upgrades and health, safety and environment were found to significantly influence the firms‟ performance whereas, drilling was found not to be a predictor to the firms‟ performance. Finally, the model analysis and survey evaluation highlighted the practices of oil operations and their role in firms‟ performance, and the proposed model explains which operation practices positively impact the firms‟ performance, which can be taken up as a guiding map for petroleum companies for aiding them to make valuable decision that leads to higher performance

L’insuffisance renale chronique terminale en Algerie: Aspects epidemiologiques et economiques

L’insuffisance rénale chronique terminale (IRCT) est un problème majeur de santé publique aussi bien dans les pays développés qu’en voie de développement. Sa prise en charge génère un coût conséquent qui se reflète tout d’abord dans les coûts directs liés aux différents traitements de la pathologie. Il se reflète également dans les coûts indirects associés aux pertes que la maladie occasionne en termes d’activité économique. L’objectif de cet article est triple. Il s’agit d’abord d’analyser les données épidémiologiques algériennes sur l’IRCT. Puis, nous procéderons à une évaluation du coût hospitalier de la prise en charge d’un insuffisant rénal chronique au stade terminal au niveau du CHU de Béjaïa. Nous tenterons enfin d’identifier les facteurs qui entravent le développement de la greffe rénale en Algérie, qui trouve pourtant sa justification économique, pour proposer des recommandations à même de permettre son développement.Mots clés: Insuffisance rénale chronique terminale, Greffe rénale, Evaluation économique en santé, Algérie, Béjaï

How Cholesterol Constrains Glycolipid Conformation for Optimal Recognition of Alzheimer's β Amyloid Peptide (Aβ1-40)

Membrane lipids play a pivotal role in the pathogenesis of Alzheimer's disease, which is associated with conformational changes, oligomerization and/or aggregation of Alzheimer's β-amyloid (Aβ) peptides. Yet conflicting data have been reported on the respective effect of cholesterol and glycosphingolipids (GSLs) on the supramolecular assembly of Aβ peptides. The aim of the present study was to unravel the molecular mechanisms by which cholesterol modulates the interaction between Aβ1–40 and chemically defined GSLs (GalCer, LacCer, GM1, GM3). Using the Langmuir monolayer technique, we show that Aβ1–40 selectively binds to GSLs containing a 2-OH group in the acyl chain of the ceramide backbone (HFA-GSLs). In contrast, Aβ1–40 did not interact with GSLs containing a nonhydroxylated fatty acid (NFA-GSLs). Cholesterol inhibited the interaction of Aβ1–40 with HFA-GSLs, through dilution of the GSL in the monolayer, but rendered the initially inactive NFA-GSLs competent for Aβ1–40 binding. Both crystallographic data and molecular dynamics simulations suggested that the active conformation of HFA-GSL involves a H-bond network that restricts the orientation of the sugar group of GSLs in a parallel orientation with respect to the membrane. This particular conformation is stabilized by the 2-OH group of the GSL. Correspondingly, the interaction of Aβ1–40 with HFA-GSLs is strongly inhibited by NaF, an efficient competitor of H-bond formation. For NFA-GSLs, this is the OH group of cholesterol that constrains the glycolipid to adopt the active L-shape conformation compatible with sugar-aromatic CH-π stacking interactions involving residue Y10 of Aβ1–40. We conclude that cholesterol can either inhibit or facilitate membrane-Aβ interactions through fine tuning of glycosphingolipid conformation. These data shed some light on the complex molecular interplay between cell surface GSLs, cholesterol and Aβ peptides, and on the influence of this molecular ballet on Aβ-membrane interactions

Feedback control of bilinear distributed parameter system by input-output linearization

International audienceIn this paper, a control law that enforces the tracking of a boundary controlled output for a bilinear distributed parameter system is developed in the framework of geometric control. The dynamic behavior of the system is described by two weakly coupled linear hyperbolic partial differential equations. The stability of the resulting closed-loop system is investigated based on eigenvalues of the spatial operator of a weakly coupled system of balance equations. It is shown that, under some reasonable assumptions, the stability condition is related to the choice of the tuning parameter of the control law. The performance of the developed control law is demonstrated, through numerical simulation, in the case of a co-current heat exchanger. The control objective is to control the outlet cold fluid temperature by manipulating its velocity. Both tracking and disturbance rejection problems are considered

Innovative treatment targeting gangliosides aimed at blocking the formation of neurotoxic alpha-synuclein oligomers in Parkinson's disease

Parkinson's disease (PD) is a major neurodegenerative disorder which exhibits many of the characteristics of a pandemic. Current therapeutic strategies are centered on the dopaminergic system, with limited efficacy, so that a treatment that has a direct impact on the underlying disease pathogenesis is urgently needed. Although alpha-synuclein is a privileged target for such therapies, this protein has been in the past wrongly considered as exclusively intracellular, so that the impact of paracrine neurotoxicity mechanisms in PD have been largely ignored. In this article we review the data showing that lipid rafts act as plasma membrane machineries for the formation of alpha-synuclein pore-like oligomers which trigger an increase of intracellular Ca2+. This Ca2+ influx is responsible for a self-sustained cascade of neurotoxic events, including mitochondrial oxidative stress, tau phosphorylation, Ca2+ release from the endoplasmic reticulum, Lewy body formation, and extracellular release of alpha-synuclein in exosomes. The first step of this cascade is the binding of alpha-synuclein to lipid raft gangliosides, suggesting that PD should be considered as both a proteinopathy and a ganglioside membrane disorder lipidopathy. Accordingly, blocking alpha-synuclein-ganglioside interactions should annihilate the whole neurotoxic cascade and stop disease progression. A pipeline of anti-oligomer molecules is under development, among which an in-silico designed synthetic peptide AmyP53 which is the first drug targeting gangliosides and thus able to prevent the formation of alpha-synuclein oligomers and all downstream neurotoxicity. These new therapeutic avenues challenge the current symptomatic approaches by finally targeting the root cause of PD through a long-awaited paradigm shift.Peer reviewe

MODELISATION DES COUTS D’ALIMENTATION EN EAU POTABLE : CAS DE LA VILLE DE BEJAIA

Le présent article porte sur une analyse économétrique des coûts des services d’alimentation en eau potable au niveau de la ville de Béjaia, et ce en appuyant sur un modèle empirique à partir d’une base de données relevant de l’Algérienne des eaux de Béjaia.Pour réaliser ce travail, nous avons appelé aux  techniques de modélisation  telles que  les procédures d'estimation de système d’équations simultanées sous contraintes à l’aide de la méthode SURE. Ce travail nous a permis  de fournir un outil d’aide à la gestion pour les  services d’eau potable au niveau de l’entreprise de gestion de la ville de Bejaia. Mots clésAlimentation en eau potable, coûts, fonction de coût translog, méthode SURE, élasticité de substitution

AmyP53 Prevents the Formation of Neurotoxic β-Amyloid Oligomers through an Unprecedent Mechanism of Interaction with Gangliosides: Insights for Alzheimer’s Disease Therapy

A broad range of data identify Ca2+-permeable amyloid pores as the most neurotoxic species of Alzheimer’s β-amyloid peptide (Aβ1–42). Following the failures of clinical trials targeting amyloid plaques by immunotherapy, a consensus is gradually emerging to change the paradigm, the strategy, and the target to cure Alzheimer’s disease. In this context, the therapeutic peptide AmyP53 was designed to prevent amyloid pore formation driven by lipid raft microdomains of the plasma membrane. Here, we show that AmyP53 outcompetes Aβ1–42 binding to lipid rafts through a unique mode of interaction with gangliosides. Using a combination of cellular, physicochemical, and in silico approaches, we unraveled the mechanism of action of AmyP53 at the atomic, molecular, and cellular levels. Molecular dynamics simulations (MDS) indicated that AmyP53 rapidly adapts its conformation to gangliosides for an optimal interaction at the periphery of a lipid raft, where amyloid pore formation occurs. Hence, we define it as an adaptive peptide. Our results describe for the first time the kinetics of AmyP53 interaction with lipid raft gangliosides at the atomic level. Physicochemical studies and in silico simulations indicated that Aβ1–42 cannot interact with lipid rafts in presence of AmyP53. These data demonstrated that AmyP53 prevents amyloid pore formation and cellular Ca2+ entry by competitive inhibition of Aβ1–42 binding to lipid raft gangliosides. The molecular details of AmyP53 action revealed an unprecedent mechanism of interaction with lipid rafts, offering innovative therapeutic opportunities for lipid raft and ganglioside-associated diseases, including Alzheimer’s, Parkinson’s, and related proteinopathies

The role of the tourism industry in local development : à case study of the municipality of Hammam Sokhna in the state of Setif

تهدف هذه الدراسة إلى التعرف على مفهوم صناعة السياحة وبيان مدى مساهمتها في التنمية المحلية بالإعتماد على السياحة الحموية كأبرز أنواع السياحة رواجا لإستقطابها العديد من المشاريع السياحية الهامة في إطار الإستثمار السياحي، كما تهدف الدراسة كذالك إلى توضيح مفهوم التنمية المحلية ومختلف الأبعاد المتعلقة بها. أما في الجانب التطبيقي، فقد تم إعداد دراسة حالة لبلدية حمام السخنة بولاية سطيف، التي تعتبر قطب سياحي حموي بإمتياز، من خلال متابعة وتحليل التدفقات السياحية والمداخيل للفترة من 2011 إلى 2021 وإنعكاساتها على التنمية المحلية بالمنطقة ومقارنتها بالبلديات المجاورة لها. حيث توصلت الدراسة إلى مجموعة من النتائج أهما: أن السياحة الحموية تلعب دورا هاما في التنمية المحلية من خلال خلق مناصب شغل جديدة وديناميكية مجالية سمحت بخلق مدينة جديدة من مجرد منبع مائي ساخن.This study aims to identify the concept of the tourism industry and to show the extent of its contribution to local development by relying on febrile tourism as the most popular type of tourism for attracting many important tourism projects within the framework of tourism investment. The study also aims to clarify the concept of local development and the various dimensions related to it. As for the practical side, a case study was prepared for the municipality of Hammam Sokhna in the state of Setif, which is considered a Hama tourist pole par excellence, by following up and analyzing tourism flows and incomes for the period from 2011 to 2021 and their repercussions on local development in the region and comparing them with neighboring municipalities. Where the study reached a set of results, Where the study reached a set of results, the most important of which are: that febrile tourism plays an important role in local development by creating new jobs and a dynamic spatial that allowed the creation of a new city from just a that allowed the creation of a new city from just a hot water source

On the Portevin-Le Chatelier instabilities in the industrial Al-2.5%Mg alloy

La localisation de la déformation plastique se présente comme un inconvénient majeur dans les procédés industriels de mise en forme des matériaux métalliques, comme l’emboutissage et le laminage. Le phénomène Portevin-Le Chatelier (PLC) est l’une des formes de la déformation plastique hétérogène observé dans une large gamme de matériaux et dans différentes conditions de sollicitation mécanique. Il se manifeste par un écoulement plastique instable et non homogène à l’échelle macroscopique. Ce comportement conduit à des caractéristiques mécaniques hétérogènes, limite la ductilité du matériau déformé et crée des zones très sensibles à la corrosion. Les zones de localisation de la déformation sont caractérisées par un comportement dilatant qui peut provoquer la rupture d’un matériau et, par conséquent, la défaillance de structures. L’origine microscopique de cet écoulement plastique instable est souvent associé au vieillissement dynamique résultant de l’interaction entre les dislocations mobiles et les nuages d’impuretés où de solutés. Dans le cadre de ce travail, nous analysons l’écoulement plastique instable de type PLC dans l’alliage industriel Al-2.5%Mg à température ambiante. Des essais de traction uniaxiale, effectués dans la gamme des vitesses de déformation imposées comprises entre 10-6 s-1 et 10-1 s-1, nous ont permis de déterminer le domaine d’instabilité et d’étudier les évolutions des paramètres caractéristiques associés en fonction de la déformation et de la vitesse de déformation. On montre que la réduction de la sensibilité de la contrainte d’écoulement à la vitesse de déformation est accompagnée d’une chute de ductilité dans le domaine d’instabilité. Les résultats expérimentaux obtenus sont analysés et discutés en liaison avec les mécanismes de vieillissement dynamique. Références [1] L.P.Kubin, Y.Estrin, Dynamic strain ageing and the mechanical response of alloys, J.Phys III 1 (1991) 929-943. [2] L.Ziani, S.Boudrahem, H.Ait-Amokhtar, M.Mehenni, B.Kedjar, Unstable plastic flow in the Al–2%Mg alloy, effect of annealing process, Mater. Sci. Eng.A 536 (2012) 239-243. [4] H.Ait-Amokhtar, C.Fressengeas, Crossover from continuous to discontinuous propagation in the Portevin–Le Chatelier effect, Acta Mater 58 (2010) 1342-1349

Synthesis, characterization and antimicrobial evaluation of 1-((5,3-diaryl)-4,5-dihydro-1H-pyrazol-1-yl)propan-1-one

1-((5,3-Diaryl)-4,5-dihydro-1H-pyrazol-1-yl)propan-1-one, 6-10, have been synthesized by the reaction of chalcone derivatives, 1-5, with hydrazine hydrate in hot propanoic acid solution. All these compounds were characterized by different spectroscopic techniques (FT-IR, 1H and 13C NMR) and elemental analyses. All the synthesized products were evaluated for antimicrobial activity. All the compounds exhibited significant to moderate antimicrobial activity