592 research outputs found

    Universities as Learning Organizations in a Cross-cultural Perspective

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    Objective: The paper attempts to link the concepts of Learning Organizations and Organizations culture with Universities within a cross-cutural perspective. Methods: After a review of literature of Learning Organizations, the author provides insight of Organizational culture definitions and attempts to analyses the challenges of cross-cultural studies for those organizations. Results: The review showed that learning organizations have been successful in implanting change. Because each University has a unique profile an ad-hoc cross-cultural analysis is needed. Conclusions/Recommendations: The debate whether Universities are learning organizations is still open. Yet, in order to become accomplished learning organizations, they should take into account their cross-cultural challenge

    Inversion-based control of electromechanical systems using causal graphical descriptions

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    Causal Ordering Graph and Energetic Macroscopic Representation are graphical descriptions to model electromechanical systems using integral causality. Inversion rules have been defined in order to deduce control structure step-bystep from these graphical descriptions. These two modeling tools can be used together to develop a two-layer control of system with complex parts. A double-drive paper system is taken as an example. The deduced control yields good performances of tension regulation and velocity tracking

    Inversion-based control of electromechanical systems using causal graphical descriptions

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    Causal Ordering Graph and Energetic Macroscopic Representation are graphical descriptions to model electromechanical systems using integral causality. Inversion rules have been defined in order to deduce control structure step-bystep from these graphical descriptions. These two modeling tools can be used together to develop a two-layer control of system with complex parts. A double-drive paper system is taken as an example. The deduced control yields good performances of tension regulation and velocity tracking

    Simulation combinée des processus de production et des processus de pilotage : analyse comparative de stratégies de pilotage pour la production de bois d'oeuvre

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    Dans le cadre de ce travail de thĂšse, nous avons conçu une plateforme de simulation permettant l’évaluation comparative de stratĂ©gies de pilotage pour la production de bois d’Ɠuvre dans les scieries nord-amĂ©ricaines. Dans notre contexte, une stratĂ©gie de pilotage est composĂ©e de plusieurs paramĂštres tels que le choix des politiques d’acceptation des commandes, permettant d’accepter ou de refuser une commande en fonction de rĂšgles mises en place, le choix des modĂšles et algorithmes de planification utilisĂ©s Ă  chaque Ă©tape de la production de bois d’Ɠuvre, le choix du modĂšle au niveau tactique, les mĂ©canismes de coordination utilisĂ©s, permettant de mieux coordonner les opĂ©rations de plusieurs entitĂ©s distinctes ou de plusieurs niveaux de planification ; on parle notamment d’échange d’informations circulant entre les niveaux de planification tactique et opĂ©rationnel ou encore entre les entitĂ©s/modĂšles utilisĂ©s au niveau opĂ©rationnel pour planifier la production de bois d’Ɠuvre. Lors de la planification des opĂ©rations, les industriels doivent mettre en place ces stratĂ©gies de pilotage. Aujourd’hui, il est extrĂȘmement compliquĂ© de savoir quelle stratĂ©gie de pilotage mettre en place en fonction de son propre contexte de marchĂ© et de ses paramĂštres de production. L’objectif gĂ©nĂ©ral est donc est de permettre d’évaluer et comparer des stratĂ©gies de pilotage aux niveaux tactique et opĂ©rationnel pour la production de bois d’Ɠuvre, tout en tenant compte du contexte de marchĂ© de l’entreprise ainsi que de ses paramĂštres de production. Pour atteindre cet objectif, nous l’avons divisĂ© en quatre objectifs spĂ©cifiques qui ont donnĂ©s lieu Ă  trois publications. Pour notre premier objectif spĂ©cifique, nous avons dĂ©veloppĂ© un modĂšle de simulation permettant de reprĂ©senter la gĂ©nĂ©ration, l’acceptation et la vente d’une commande pour une entreprise de sciage. Un module de planification de la production a Ă©galement Ă©tĂ© couplĂ© et est responsable de la gestion des stocks et de la gĂ©nĂ©ration des plans de production. Pour notre deuxiĂšme objectif spĂ©cifique, nous avons utilisons ce modĂšle de simulation pour pouvoir Ă©valuer l’impact de politiques d’acceptation des commandes (telles que Availableto-promise (ATP), Capable-to-promise (CTP) ou encore On-Stock) sur les performances de l’entreprise en termes de volume de commandes acceptĂ©es dans un environnement Ă  flux de produits divergent avec co-production. Bien que ces politiques d’acceptation des commandes aient Ă©tĂ© largement Ă©tudiĂ©es dans un contexte manufacturier traditionnel, le choix d’une politique plutĂŽt qu’une autre est loin d’ĂȘtre trivial dans un tel contexte de divergence de flux physique. Nous montrons dans cette premiĂšre contribution que dans ce type de contexte, le choix d’une politique d’acceptation de commande plutĂŽt qu’une autre dĂ©pend fortement du marchĂ© et impacte fortement les performances de l’entreprise, en termes de commandes acceptĂ©es et de stock moyen annuel. Cet objectif spĂ©cifique a entrainĂ© l’écriture d’un premier article. Pour notre troisiĂšme objectif spĂ©cifique, nous avons Ă©valuĂ© des mĂ©canismes de coordination mis en place au niveau opĂ©rationnel entre les diffĂ©rentes activitĂ©s du processus de transformation de bois d’Ɠuvre, qui est un processus dĂ©centralisĂ©. La prĂ©cĂ©dente plateforme de simulation a donc Ă©tĂ© adaptĂ©e et des mĂ©canismes de coordination dĂ©jĂ  publiĂ©s tels que « Twophases planning », ou « bottleneck-first planning » y sont Ă©valuĂ©s en utilisant un horizon roulant dans un environnement oĂč les commandes sont gĂ©nĂ©rĂ©es dynamiquement. Nous montrons que les mĂ©canismes de coordination dĂ©jĂ  publiĂ©s et testĂ©s dans un environnement statique performent mal dans un environnement dynamique. Nous proposons donc un autre mĂ©canisme de coordination « hybride flux poussĂ© / flux tirĂ© » exploitant le concept de point de dĂ©couplage. Ce mĂ©canisme s’avĂšre meilleur que les prĂ©cĂ©dents en permettant un plus grand nombre de ventes, ainsi qu’une rĂ©duction des stock moyens. Cet objectif spĂ©cifique a entrainĂ© l’écriture d’un deuxiĂšme article. Enfin, pour notre quatriĂšme objectif spĂ©cifique, nous nous intĂ©ressons Ă  la planification de la production aux niveaux tactique et opĂ©rationnel. Nous utilisons le modĂšle de simulation pour comparer et Ă©valuer l’impact de diffĂ©rents types d’informations transmises du niveau tactique au niveau opĂ©rationnel. Le niveau de planification tactique est alors pris en compte pour Ă©tablir une planification Ă  plus long terme. Nous montrons que le choix du type d’informations Ă  transmettre du niveau tactique au niveau opĂ©rationnel varie selon plusieurs facteurs, tels que : la politique d’acceptation des commandes (ATP, CTP) utilisĂ©e par l’entreprise, l’ampleur de la saisonnalitĂ© des prix de vente, ou le fait d’ĂȘtre ou non dans un marchĂ© en surcapacitĂ©. Cet objectif spĂ©cifique a entrainĂ© l’écriture d’un troisiĂšme article.In this thesis, we designed a simulation platform to compare and evaluate production planning and order management strategies for lumber production in North American sawmills. In our context, a strategy is composed of several parameters such as the choice of order acceptance policies, allowing to accept or refuse an order based on implemented rules, the choice of planning models and algorithms used at each stage of timber production, the choice of model at the tactical level, the coordination mechanisms used, to better coordinate the operations of several distinct entities or of several planning levels; this includes the exchange of information between tactical and operational planning levels or between entities / models used at the operational level to plan timber production. Today, it is extremely difficult for a company to know which management strategy to put in place. The general objective is then to evaluate and compare tactical and operational planning strategies for timber production, taking into account the company's market context and its production parameters. To achieve this goal, we divided it into four specific objectives that resulted in three publications. In the first specific objective, we developed a simulation model to represent the generation, acceptance and sale of an order for a sawmill. We coupled a production planning module to this simulation model that is responsible for inventory management and the generation of production plans. In a second objective, we use this simulation model to be able to evaluate the impact of order acceptance policies such as Available-to-promise (ATP), Capable-to-promise (CTP) and Stock policies on the company’s performance in terms of volume of accepted orders in a product flow environment diverge with co-production. Although these order acceptance policies have been widely studied in a traditional manufacturing context, the choice of one policy over another is far from being trivial in such a context of divergence flow. We show that in this type of context, the choice of an order acceptance policy rather than another depends strongly on the market and impacts the performance of the company, in terms of accepted orders and average annual inventory. This specific objective leads to the first publication. In a third specific objective, we evaluated coordination mechanisms used at the operational level between the different activities of the timber processing process, which is a decentralized process. The previous simulation platform has been adapted and previously published coordination mechanisms such as "Two-phase planning" or "bottleneck-first planning" are evaluated using a rolling horizon in an environment where orders are generated dynamically. We show that coordination mechanisms already published and tested in a static environment perform poorly in a dynamic environment. We therefore propose another "hybrid push / pull" coordination mechanism exploiting the decoupling point concept. This mechanism is better than the previous ones by allowing a greater number of sales, as well as a reduction in average inventory. This specific objective leads to a second publication. Finally, in a fourth specific objective, we are interested in production planning at the tactical and operational levels. We use the simulation model to compare and evaluate different information transmitted from the tactical level to the operational level by simulating the production system, the planning process and the market behavior. The tactical planning level is then taken into account to establish longer-term production planning. We show that the choice of the type of information to be transmitted from the tactical level to the operational level varies according to several factors, such as: the order acceptance policy (ATP, CTP) used by the company, the extent of seasonality selling prices, or whether or not being in an overcapacity market. This specific objective leads to third publicatio

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    This article is an attempt to understand communication’s patterns and styles, and it also shows the importance of the awareness of the principles of communication to cross-cultural management

    The Urea Carboxylase and Allophanate Hydrolase Activities of Urea Amidolyase Are Functionally Independent

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    Urea amidolyase (UAL) is a multifunctional biotin-dependent enzyme that contributes to both bacterial and fungal pathogenicity by catalyzing the ATP-dependent cleavage of urea into ammonia and CO2. UAL is comprised of two enzymatic components: urea carboxylase (UC) and allophanate hydrolase (AH). These enzyme activities are encoded on separate but proximally related genes in prokaryotes while, in most fungi, they are encoded by a single gene that produces a fusion enzyme on a single polypeptide chain. It is unclear whether the UC and AH activities are connected through substrate channeling or other forms of direct communication. Here, we use multiple biochemical approaches to demonstrate that there is no substrate channeling or interdomain/intersubunit communication between UC and AH. Neither stable nor transient interactions can be detected between prokaryotic UC and AH and the catalytic efficiencies of UC and AH are independent of one another. Furthermore, an artificial fusion of UC and AH does not significantly alter the AH enzyme activity or catalytic efficiency. These results support the surprising functional independence of AH from UC in both the prokaryotic and fungal UAL enzymes and serve as an important reminder that the evolution of multifunctional enzymes through gene fusion events does not always correlate with enhanced catalytic function

    The Absence of C-5 DNA Methylation in Leishmania donovani Allows DNA Enrichment from Complex Samples.

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    Cytosine C5 methylation is an important epigenetic control mechanism in a wide array of eukaryotic organisms and generally carried out by proteins of the C-5 DNA methyltransferase family (DNMTs). In several protozoans, the status of this mechanism remains elusive, such as in Leishmania, the causative agent of the disease leishmaniasis in humans and a wide array of vertebrate animals. In this work, we showed that the Leishmania donovani genome contains a C-5 DNA methyltransferase (DNMT) from the DNMT6 subfamily, whose function is still unclear, and verified its expression at the RNA level. We created viable overexpressor and knock-out lines of this enzyme and characterized their genome-wide methylation patterns using whole-genome bisulfite sequencing, together with promastigote and amastigote control lines. Interestingly, despite the DNMT6 presence, we found that methylation levels were equal to or lower than 0.0003% at CpG sites, 0.0005% at CHG sites, and 0.0126% at CHH sites at the genomic scale. As none of the methylated sites were retained after manual verification, we conclude that there is no evidence for DNA methylation in this species. We demonstrated that this difference in DNA methylation between the parasite (no detectable DNA methylation) and the vertebrate host (DNA methylation) allowed enrichment of parasite vs. host DNA using methyl-CpG-binding domain columns, readily available in commercial kits. As such, we depleted methylated DNA from mixes of Leishmania promastigote and amastigote DNA with human DNA, resulting in average Leishmania:human enrichments from 62× up to 263×. These results open a promising avenue for unmethylated DNA enrichment as a pre-enrichment step before sequencing Leishmania clinical samples

    G-quadruplex RNA motifs influence gene expression in the malaria parasite Plasmodium falciparum.

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    Funder: Hong Kong PhD Fellowship SchemeFunder: Hong Kong Special Administrative Region GovernmentG-quadruplexes are non-helical secondary structures that can fold in vivo in both DNA and RNA. In human cells, they can influence replication, transcription and telomere maintenance in DNA, or translation, transcript processing and stability of RNA. We have previously showed that G-quadruplexes are detectable in the DNA of the malaria parasite Plasmodium falciparum, despite a very highly A/T-biased genome with unusually few guanine-rich sequences. Here, we show that RNA G-quadruplexes can also form in P. falciparum RNA, using rG4-seq for transcriptome-wide structure-specific RNA probing. Many of the motifs, detected here via the rG4seeker pipeline, have non-canonical forms and would not be predicted by standard in silico algorithms. However, in vitro biophysical assays verified formation of non-canonical motifs. The G-quadruplexes in the P. falciparum transcriptome are frequently clustered in certain genes and associated with regions encoding low-complexity peptide repeats. They are overrepresented in particular classes of genes, notably those that encode PfEMP1 virulence factors, stress response genes and DNA binding proteins. In vitro translation experiments and in vivo measures of translation efficiency showed that G-quadruplexes can influence the translation of P. falciparum mRNAs. Thus, the G-quadruplex is a novel player in post-transcriptional regulation of gene expression in this major human pathogen.UK Medical Research Council [grants MR/K000535/1 and MR/L008823/1] to CJM. Shenzhen Basic Research Project [JCYJ20180507181642811], Research Grants Council of the Hong Kong SAR, China Projects [CityU 11100421, CityU 11101519, CityU 11100218, N_CityU110/17, CityU 21302317], Croucher Foundation [Project No. 9500030, 9509003], State Key Laboratory of Marine Pollution Director Discretionary Fund, City University of Hong Kong [projects 6000711, 7005503, 9667222, 9680261] to CKK. A generous donation from Mr. and Mrs. Sunny Yang, the University Grants Committee Area of Excellence Scheme (AoE/M-403/16), and the Innovation and Technology Commission, Hong Kong Special Administrative Region Government to the State Key Laboratory of Agrobiotechnology (CUHK) to TFC. EYCC was supported by the Hong Kong PhD Fellowship Scheme
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