Ring Polymers in Entangled Solutions: Complex Structure and Heterogeneous Dynamics

Understanding how topological constraints affect the structure and dynamics of polymers in solution is a historical challenge in polymer physics: in particular, it still represents the goal of all modern studies aiming at understanding the behavior of concentrated solutions of ring polymers. Ring polymers represent in fact some of the most puzzling objects in polymer physics: at odds with their linear counterparts they do not swell assuming ideal conformations, but they fold into compact, space-filling conformations. At the same time though, rings maintain a considerable degree of mutual interpenetration in the form of \threading", which is at the basis of their surprisingly rich mechanical and rheological behavior. In this Thesis, I investigate general and universal properties of ring polymers emerging in concentrated solutions. Notably, I discuss the scaling behavior of structural and dynamical quantities of single rings being surrounded by neighboring polymers exerting volume interactions on each other. Then, I consider important connection between \threadings" in close-by rings and their consequent slowing down. For the systems under analysis, I employ extensive Molecular Dynamics computer simulations in order to provide a detailed description concerning the equilibrium and dynamical properties of ring polymers in solutions of different densities. For systematic comparison, we also discuss the same properties for their linear counterparts

We\u27ve Got Mail: Email Preservation at a Small, Private University

This paper discusses the obstacles and solutions to implementing an email preservation system at a small university. I reviewed five possible programs for the best fit for the situation, though only three were considered seriously for implementation. At the conclusion, I discuss why the path taken was most appropriate, which may benefit others looking to implement similar systems

“No Rhyme or Reason:” Surveying Legislative Records Retention Practices in the U.S. House of Representatives

Because the records of individual Members of the House of Representatives are considered personal property, what happens to those records once a Member leaves office is up to him or her. Legislative records, particularly files and reports used to develop policy and draft bills, have historical value and are one of the types of files most used in current Congressional collections, as they point toward legislative intent. The House Records Management Manual for Members suggests that offices permanently maintain these types of files. This study reveals to what extent House offices are preserving records that provide future researchers with legislative intent, finding that while congressional staffs are not largely aware of the manual, they do attempt to preserve differing types of legislative background materials. There is a general awareness that their practices have room for improvement, but with no requirements to implement a retention schedule, there is little incentive for congressional staffs to develop better records management procedures

Nanoprobe diffusion in entangled polymer solutions: Linear vs. unconcatenated ring chains

We employ large-scale molecular dynamics computer simulations to study the problem of nanoprobe diffusion in entangled solutions of linear polymers and unknotted and unconcatenated circular (ring) polymers. By tuning both the diameter of the nanoprobe and the density of the solution, we show that nanoprobes of diameter smaller than the entanglement distance (tube diameter) of the solution display the same (Rouse-like) behavior in solutions of both polymer architectures. Instead, nanoprobes with larger diameters appear to diffuse markedly faster in solutions of rings than in solutions of linear chains. Finally, by analysing the distribution functions of spatial displacements, we find that nanoprobe motion in rings' solutions shows both Gaussian and ergodic behaviors, in all regimes considered, while, in solutions of linear chains, nanoprobes exceeding the size of the tube diameter show a transition to non-Gaussian and non-ergodic motion. Our results emphasize the role of chain architecture in the motion of nanoprobes dispersed in polymer solutions

Keep It or Toss It? Legislative Records Retention Practices in the U.S. House of Representatives

Because the records of individual Members of the House of Representatives are considered personal property, what happens to those records once a Member leaves office is up to him or her. Legislative records, particularly files and reports used to develop policy and draft bills, have historical value and are one of the types of files most used in current Congressional collections, as they point toward legislative intent. The House Records Management Manual for Members suggests that offices permanently maintain these types of files. This study reveals to what extent House offices are preserving records that provide future researchers with legislative intent, finding that while congressional staffs are not largely aware of the manual, they do attempt to preserve differing types of legislative background materials. There is a general awareness that their practices have room for improvement, but with no requirements to implement a retention schedule, there is little incentive for congressional staffs to develop better records management procedures.Master of Science in Library Scienc

Base de données lexicales : application au Dictionnaire d’électrotechnique Français–Amazigh de M. Mahrazi

La construction d’une base de données lexicales (BDL) est un préalable pour tout traitement automatique d’une langue (traduction automatique, correcteurs orthographiques, dictionnaires électroniques...). En effet, la BDL se présente sous forme d’informations, généralement d'ordre linguistique organisés en vue de leur utilisation par des programmes informatiques. La façon la plus directe de construire des bases de données lexicales est d’utiliser des dictionnaires et de les transformer en entités informatiques. C’est l’approche adoptée par la plupart des éditeurs de dictionnaires électroniques. Les produits qui résultent de cette informatisation peuvent être appelés bases de données dictionnairiques.L’objectif de ce travail s’inscrit dans la perspective d’aménagement de la langue amazighe, il consiste en une création d’une base de données lexicale et son application au Dictionnaire d’électrotechnique français –amazigh de M. Mahrazi, en utilisant l’Access 2007

Initiation d’une base de données toponymique

Le dernier événement de Tigentourin a montré les défaillances du système toponymique algérien. Un même lieu peut être transcrit de plusieurs manières ce qui peut induire en erreur, aussi bien les services de sécurité avec les conséquences néfastes qui peuvent en découler, que les scientifiques qui s’embourberaient dans la recherche d’interprétations à un nom qui n’a aucune existence dans la réalité.D’une autre côte, il est bien connu depuis A. Dauzat et A. Pellegrin, pour l’Afrique du Nord, que la meilleure interprétation d’un toponyme est celle qui s’articule sur la loi des séries et qui tienne compte des idiomes locaux.Afin de faciliter la constitution de ces séries et la localisation géographique d’un toponyme, nous nous sommes engagés dans l’initiation d’une base de données toponymique

Essai de création d’un générateur automatique de l’état d’annexion

Le présent travail s’inscrit dans la perspective du traitement automatique de la langue amazighe, qui consiste est un Essai de création d’un générateur automatique de l’état d’annexion kabyle en utilisant le logiciel C++ Builder. Il vise, d’une part, l’utilisation de l’enseignement assisté par ordinateur de l’amazighe (EAO), et d’autre part, il contribuera dans le processus de l’aménagement de la langue amazighe en disposant à cette langue un programme susceptible de générer l’état d’annexion de tous les noms amazighs (kabyles)