Esta pesquisa se propõe a realizar um estudo crítico-reflexivo baseado nas cinco obras do pintor italiano Arturo Tosi (Busto Arsizio, 1871 Milão, 1956), pertencentes ao acervo do Museu de Arte Contemporânea da Universidade de São Paulo (MAC USP). O objetivo é compreender essas pinturas no contexto da produção do artista, sem deixar de considerá-las no entanto à luz do complexo sistema das artes na Itália da primeira metade do século XX. Traçando detalhadamente o percurso que cada obra percorreu até às origens da primeira coleção italiana do antigo Museu de Arte Moderna de São Paulo MAM SP, este estudo pretende aprofundar o intercâmbio entre Brasil e Itália no âmbito da arte moderna, com especial referência às políticas culturais da Itália no período fascista. Assim estabelecido, a pesquisa propõe não só ilustrar os parâmetros que parecem ter sido, para Ciccillo Matarazzo, fundamentais na escolha das obras de Arturo Tosi, como também suas significações mais complexas no discurso da arte moderna nacional. / A critical and reflective study based on five works of the Italian painter Arturo Tosi (Busto Arsizio, 1871 Milan, 1956), part of Museum of Contemporary Art, University of São Paulo (MAC USP) collection, is the main objective that this research aims to accomplish. This study looks at the understanding of these works of art, either from his artistic production perspective or from the view of the early 20th century Italian Art system. By following the path of each painting, since its conception until the origins of the first Italian collection of the Museum of Modern Art of São Paulo (MAM SP), this study intends to research the interrelations between Brazilian and Italian modern art, with special reference to cultural policies in the Italian fascist period. This research also proposes not only to bring the essential parameters for Ciccillo Matarazzo in his selection of Arturo Tosis artworks, as well as their most complex meanings in the discourse of national modern art.

Esta pesquisa de mestrado tem por objetivo o estudo das quatro obras do pintor italiano Gino Severini (Cortona, 1883 Paris, 1966) pertencentes ao acervo do Museu de Arte Contemporânea da Universidade de São Paulo (MAC USP), que são: Natura Morta con Piccioni [Natureza-morta com pombas], c. 1938; Figura con Pagina di Musica [Figura com página de música], c. 1942; Fiori e Libri [Flores e livros], c. 1942; e La Femme et Larlequin [A mulher e o arlequim], 1946. A partir da análise dessas pinturas, discutimos a trajetória de Severini, na medida em que esclarece tanto o contexto em que estava operando quando as produziu, quanto o histórico de sua formação como artista. Feitas essas reflexões, apresentamos o caminho que essas obras percorreram da Itália para a primeira coleção italiana do antigo Museu de Arte Moderna de São Paulo (MAM SP) de onde as quatro obras de Severini provêm , bem como a recepção que o artista e suas obras tiveram no ambiente artístico brasileiro entre as décadas de 1940 e 1950. O estudo pretende elucidar o porquê de justamente essas quatro obras terem sido compradas em detrimento de tantas outras do artista, e o quanto essa escolha está vinculada com o perfil maior das 67 aquisições de obras italianas para o antigo MAM SP. / The aim of this masters research is the study of the four artworks by the Italian painter, Gino Severini, (Cortona, 1883Paris, 1966), that belong to the University of São Paulos Museum of Contemporary Art (MAC USP), which are: Natura Morta con Piccioni [Still life with doves], c. 1938; Figura con Pagina di Musica [Figure with music score], c. 1942; Fiori e Libri [Flowers and books], c. 1942; and La Femme et Larlequin [Woman and harlequin], 1946. Based on the detailed analysis of such artworks, we discuss Severinis trajectory in the period, as it clarifies both the context in which he was operating when they were produced and the history of his background as an artist. That being said, we present the pathway that these artworks took from Italy to the first Italian collection of the former Museum of Modern Art of São Paulo (MAM SP) where Severinis four artworks come fromas well as the reception that the artist and his artworks enjoyed in the Brazilian artistic milieu between the 1940s and 1950s. The study aims to elucidate the precise reason why these four artworks were bought instead of many others by the artist, and to what extent this choice is related to the greater profile of the acquisition of the sixty-seven Italian artworks for the former MAM SP.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2018-03-27T12:48:33Z No. of bitstreams: 1 guilhermenogueirarangone.pdf: 2375589 bytes, checksum: 6829bf1bcfd4735727351c834bb1b1e3 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-04-09T19:20:00Z (GMT) No. of bitstreams: 1 guilhermenogueirarangone.pdf: 2375589 bytes, checksum: 6829bf1bcfd4735727351c834bb1b1e3 (MD5) / Made available in DSpace on 2018-04-09T19:20:00Z (GMT). No. of bitstreams: 1 guilhermenogueirarangone.pdf: 2375589 bytes, checksum: 6829bf1bcfd4735727351c834bb1b1e3 (MD5) Previous issue date: 2018-02-22 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Passado o século XX, nota-se uma mudança considerável no que cerne aos museus ao redor do mundo, hoje, grandes museus em áreas renovadas de centros urbanos degradados, junto à realização de eventos de caráter internacional têm sido transformadas em produtos para promoção das cidades que se projetam globalizadas. Assim, a audiência converte-se em um papel importante no sucesso das instituições e é questão central no reconhecimento dos museus como agregadores de valor na malha urbana, gerando funções que até então não se observavam. A pesquisa elucida a questão sobre quais são as funções dos museus contemporâneos e como elas se relacionam, tendo como hipótese de trabalho, que as funções básicas são as de colecionar, conservar, estudar, interpretar e expor. Este trabalho compreendeu a relação entre museus e funções, e quais e como os desdobramentos funcionais se fazem presentes nessa tipologia arquitetônica. Através de uma pesquisa exploratória, com metodologia dividida em uma fase de revisão de literatura e, uma fase empírica. Tomou-se o Museu do Amanhã, no Rio de Janeiro, e o Museu de Arte Contemporânea de Niterói como casos exemplares, visando à verificação de como as funções se manifestam nesses museus, ampliando a coleta de dados para além daqueles encontrados no referencial teórico. Ao final, com a explicitação das funções dos museus contemporâneos, ratifica-se e amplia-se a hipótese inicial da pesquisa. Somam-se a ela, outros desdobramentos funcionais que possuem maior relevância no recorte proposto do que as funções apontadas inicialmente, como as funções teóricas, simbólicas e estéticas. Conclui-se assim, que os museus contemporâneos são objetos polifuncionais e que suas funções extrapolam as funções práticas exercidas nele, tendo nos dias de hoje um papel simbólico fundamental para os centros urbanos. / Since the twentieth century, there has been a considerable change in museums around the world, today, large museums in renovated areas of degraded urban centers, along with international events have been transformed into products for the promotion of cities which are globalized. Thus, the audience becomes an important role in the success of the institutions and is a central question in the recognition of the museums as value aggregators in the urban network, generating functions that until then were not observed. The research elucidates the question of what are the functions of contemporary museums and how they relate, based on a working hypothesis, that the basic functions are to collect, to preserve, to study, to interpret and to expose. This work understood the relation between museums and functions, and what and how the functional unfoldings are present in this architectural typology. Through an exploratory research, with methodology divided in a documentary phase with the literature review, and an empirical phase with the accomplishment of studies in exemplary cases. The Museum of Tomorrow in Rio de Janeiro and the Museum of Contemporary Art of Niterói were chosen, aiming at verifying how functions manifest themselves, in addition to expanding the results beyond the theoretical framework. At the end, with the explication of the functions of contemporary museums, the initial hypothesis of the research is ratified and expanded. Added to it are other functional unfoldings that have more relevance in the proposed cut than the functions initially pointed out, such as theoretical, symbolic and aesthetic functions. We conclude that contemporary museums are multi-functional objects and that their functions extrapolate the practical functions exercised in it, having today a fundamental symbolic role for urban centers

Les Wireless Body Area (WBAN) sont une technologie de réseau sans fil basée sur les radio-fréquences qui consiste à interconnecter sur, autour ou dans le corps humain de minuscules dispositifs pouvant effectuer des mesures (capteurs). Ces réseaux sont considérés comme les plus critiques dans les réseaux de capteurs sans fil. Ils sont basés sur des architectures de réseaux auto-organisés. Chacun des capteurs corporels reçoit ou envoie des paquets du ou au coordinateur du réseau. Ce dernier est responsable de l'ordonnancement des tâches pour l'ensemble des noeuds fils. L'ordonnancement dans les WBAN nécessite un mécanisme dynamique et adaptatif pour gérer les cas d'urgence qui peuvent se produire et permet ainsi d'améliorer les paramètres les plus importants comme la qualité de la transmission, le temps de réponse, le débit, le taux de paquets délivres, etc.Dans ces travaux de thèse, nous avons proposé trois techniques d'ordonnancement qui sont : la méthode semi-dynamique; la méthode dynamique et la méthode basée sur la priorité. De plus, une étude sur les plateformes WBAN est présentée. Dans cette étude, nous avons proposé une classification et une évaluation qualitative des plateformes déjà existantes. Nous avons aussi étudier les modèles de mobilité en proposant une architecture permettant de les décrire. Nous avons aussi mis en place une procédure de diagnostique afin de détecter rapidement des maladies épidémiques dangereuses. Par la suite, ces différentes propositions ont été validées en utilisant deux méthodes afin de vérifier leur faisabilité. Ces méthodes sont la simulation avec OPNET et l'implémentation réelle sur des capteurs TelosB et TinyOS. / The Wireless Body Area Network (WBAN) is the most critical field when considering Wireless Sensor Networks (WSN). It must be a self-organizing network architecture, meaning that it should be able to efficiently manage all network architecture requirements. The WBAN usually contains at least two or more body sensors. Each body sensor sends packets to or receives packets from the Personal Area Network Coordinator (PANC). The PANC is responsible for scheduling its child nodes' tasks. Scheduling tasks in the WBAN requires a dynamic and an adaptive process in order to handle cases of emergency that can occur with a given patient. To improve the most important parameters of a WBAN, such as quality link, response time, throughput, the duty-cycle, and packet delivery, we propose three scheduling processes: the semi-dynamic, dynamic, and priority-based dynamic scheduling approaches.In this thesis, we propose three task scheduling techniques, Semi-Dynamic Scheduling (SDS), Efficient Dynamic Scheduling (EDS) and High Priority Scheduling (HPS) approaches. Moreover, a comprehensive study has been performed for the WBAN platforms by classifying and evaluating them. We also investigate the mobility model for the WBANs by designing an architecture that describe this model. In addition, we detail a diagnosis procedure by using classification methods in order to solve very sensitive epidemic diseases. Then, our proposals have been validated using two techniques to check out the feasibility of our proposals. These techniques are simulation scenarios using the well-known network simulator OPNET and real implementations over TelosB motes under the TinyOS system.

Per definition så befinner sig Nordkorea och Sydkorea i krig med varandra sedan 25 juni 1950. Den aktiva delen av kriget varade endast i tre år och avlöstes av Armistice Agreement 27 juli 1953. Avtalet syftade till att möjliggöra för politiska företrädare att enas om ett fredsavtal – något man aldrig lyckades uppnå. Denna uppsats analyserar tiden från Kairokonferensen 1943 intill Armistice Day 1953 utifrån hur bakomliggande incitament – sett ur realistiska och liberalistiska perspektiv inom ramen för internationella relationer – kan förklara händelseutvecklingen på den koreanska halvön. Resultatet visar på hur erfarenheter och efterbörd av VK II, politiska målsättningar, misstro mellan parterna och till FN, successivt bygger upp dagens delade Korea utifrån vad som främst återfinns inom den realistiska teoribildningen. / North Korea and South Korea has been at war with each other since June 25, 1950. The active part of the war lasted only three years, which resulted in the Armistice Agreement July 27, 1953. The main purpose of the agreement was to allow political representatives to open up for diplomatic negotiations and agree on a peace agreement – something they never managed to achieve.  This paper will analyze the time from the Cairo Conference in 1943 until Armistice Day in 1953, and investigate how realistic and liberalized political forces, in the context of International Relations theory, influenced the developments on the Korean Peninsula. The conclusions will show how the post-war reconstructions of WW II, U.S. and Soviet foreign policy objectives and UN intervention gradually shaped a permanent landmark at the 38th parallel based on realistic values.

Staphylococcus aureus est un des pathogènes majeurs impliqué dans les mammites chez les ruminants. Il engendre des tableaux cliniques très variable, allant des mammites subcliniques aux mammites gangréneuses, mais les mécanismes de cette variabilité restent encore mal connu. La volonté de réduire l'utilisation d'antibiotiques en médecine vétérinaire ainsi que leurs faibles efficacités contre les mammites staphylococciques soulignent la nécessité de développer de nouvelles stratégies alternatives. L'une des particularités des infections intramammaires à S. aureus est leur pouvoir chronique et persistent dont l'une des principales causes est la capacité de S. aureus à adhérer et internaliser dans les tissus de l'Hote. L'un des concepts ayant fait ses preuves chez l'Homme et l'animal se base sur le concept de la lutte biologique en utilisant les propriétés inhibitrices des bactéries dites « probiotique » d'un écosystème pour réduire, prévenir ou traiter les infections. Cette étude vise à mieux caractériser le microbiote mammaire et notamment la composante lactique qui par analogie avec les autres écosystèmes jouent un rôle positif sur la santé de l'Hôte et de déterminer son potentiel à moduler l'adhésion et l'internalisation de S. aureus. L'ensemble de ce travail a été réalisé avec deux souches de S. aureus très différentes au niveau des tableaux cliniques engendrés. La souche RF122, très virulente et la souche Newbould 305, induisant des infections chroniques. Deux messages clairs ressortent des analyses indépendantes du pathogène et du microbiote : d'une part, l'édute comparative in silico et in vitro révèle que l'invasion cellulaire semble être majeur pour la chronicité de la souche Newbould 305 et d'autre part que l'écosystème de la glande mammaire présente une composante lactique ayant des capacités probiotiques intéressantes. Dans notr! e modèle d'interaction tripartite, trois acteurs ont été retenus, S. aureus, Lactobacillus casei et les cellules épithéliales mammaires MAC-T. Dans ce système, L. casei affecte l'adhésion et surtout l'internalisation de S. aureus sans modifier la viabilité et la morphologie des cellules en culture. Les mécanismes identifiés dans l'inhibition semblent dépendant d'un contact direct avec des L. casei viables et permettent de poursuivre la caractérisation des bases moléculaires de ce phénomènes impliquant une modulation des gènes de virulence et cellulaire lors d'interaction avec une flore compétitrice. Ces résultats ouvrent de nouvelles perspectives dans l'application de bactéries lactiques en tant que probiotique mammaire. / Staphylococcus aureus is one of the main pathogen involved in ruminant mastitis. Severity of bovine S. aureus mastitis is highly variable, from subclinical to gangrenous mastitis. Nevertheless S. aureus factors that may explain this variability still poorly documented. The need to reduce antibiotics in veterinary medicine as well as their low efficiencies against staphylococcal mastitis underline the necessity to develop new alternative strategies. One of the particularity of S. aureus infections is his ability to persist within the mammary tissue and induce chronicity of the infection. One of the main causes is the ability of S. aureus to adhere to and internalize into host cells. The concept of biological control, using natural inhibitory properties of lactic acid bacteria as probiotics, are now well etablished in human and animal ecosystem for their ability to reduce, prevent or treat bacterial infections. This study aims to better characterize the mammary microbiota in p! articular the lactic component which by analogy with the other ecosystems play a positive role in the host health and to determine his potential to modulate adhesion and internalization of S. aureus. This work was realized with two S. aureus strains with different severity degree. The virulent strain RF122 and the Newbould 305 one, involved in chronic mastitis. Two main messages came out from the independent analyses of the pathogen and the microbiota: on one hand, the in silico and in vitro comparison of the two strains reveals that the cellular invasion propress seems to be major for the chronicity of the Newbould 305 strain and on the other hand that the bovin mammary ecosystem presents a lactic biodiversity with interesting probiotic capacities. In our model of tripartite interaction, three actors were retained, S. aureus, Lactobacillus casei and the mammary epithelial cells MAC-T. In this system, L. casei affect the adhesion and internalization of S. aureus without mod! ifying the viability and the morphology of cells in culture. Mechanisms identified in the inhibition seem dependent on a direct contact with live L. casei and allow to continue the molecular basis of the virulence and cells genetic expression modulation during interaction with a competitive flora. These results open new perspectives in the application of lactic acid bacteria as mammary probiotic.

L'utilisation des canaux multiples améliore significativement les performances globales des réseaux de capteurs sans fil (RCSF) en permettant des transmissions parallèles sur plusieurs canaux. Cependant, la mise en place d’un protocole MAC multi-canal dans un réseau multisauts nécessite une méthode efficace d’allocation des canaux pour permettre une coordination entre les nœuds afin de partager les canaux disponibles. Dans cette thèse, nous nous intéressons à la conception d’un protocole MAC multi-canal qui répond aux exigences des applications de collecte de données à haut débit dans un réseau multi-saut. Pour ce faire, nous abordons d’abord les principales façons d’utiliser plusieurs canaux pour réaliser le partage du médium. Ensuite, nous proposons un protocole MAC multi-canal, répondant aux exigences des RCSF à haut débit, qui combine les trois techniques TDMA, CSMA et FDMA. En effet, nous utilisons une nouvelle méthode d’allocation des canaux qui permet aux nœuds de choisir le canal de réception le plus convenable dans leurs voisinages jusqu’à 3-sauts d’une façon distribuée afin de minimiser les effets des interférences et des collisions. Enfin, nous évaluons par simulation les performances de notre protocole et nous le comparons à d’autres protocoles proposés dans la littérature. Les résultats obtenus montrent l’efficacité de notre proposition dans les différents scénarios étudiés. / The use of multi-channel significantly improves the overall network performance of wireless sensor networks (WSNs) by allowing parallel transmissions over multiple channels. However, the design of a multi-channel MAC protocol in a multi-hop network requires an efficient channel allocation method that allows the coordination between the nodes in order to share available channels. In this thesis, we focus on the conception of a multi-channel MAC protocol that meets the requirements of high data collection applications in a multi-hop network. In order to achieve this goal, we first present the main techniques to use multiple channels to realize medium access sharing. Then, we propose a multi-channel MAC protocol that meets the requirements of high data rate WSNs, which combines three techniques TDMA, FDMA and CSMA. Indeed, we use a new channel assignment method that enables nodes to choose the most convenient channel in their 3-hop neighborhood in a distributed manner in order to minimize the effects of interferences and collisions. Finally, we evaluate by simulation the performance of our protocol and we compare it to other protocols proposed in the literature. The results show the efficiency of our proposition in the different studied scenarios.

A galectina-1 (Gal-1) é uma lectina homodimérica multifuncional capaz de reconhecer e se ligar a beta-galactosídeos por meio de um domínio denominado carbohydrate recognition domain (CRD). A Gal-1 humana (Gal-1h) e a Gal-1 de camundongo (Gal-1c) mantêm 88,15% de homologia e, apesar de não existirem mutações em aminoácidos-chave do CRD, há substituições próximas a esses resíduos. Considerando as implicações dessas diferenças em estrutura e função, e que é comum a utilização de modelos murinos para estudar a função Gal-1, o presente trabalho objetiva analisar comparativamente a Gal-1c e a Gal-1h por meio de ensaios de cristalização e determinação estrutural da Gal-1c, além da avaliação comparativa da atividade lectínica da Gal-1h e da Gal-1c por glycan array e hemaglutinação. Também foi avaliada a capacidade de ambas as Gal-1 em induzir a exposição de fosfatidilserina (FS) em neutrófilos ativados provenientes de medula de camundongos normais ou deficientes de ?-2 integrina (Mac-1), de modo a investigar se a interação Gal-1/Mac-1 estaria envolvida nesse processo. Preparações homogêneas e ativas de Gal-1c e Gal-1h foram utilizadas nos ensaios. Os cristais de Gal-1c foram obtidos em 20% de polietilenoglicol 3350 e 0,2 M de fluoreto de amônio. Os dados de difração de raios X foram coletados e processados, obtendo-se uma estrutura com resolução de 2,4 Å. Observou-se que substituições de aminoácidos entre a Gal-1c e a Gal-1h estão localizadas em regiões expostas ao solvente, próximas do CRD e distantes da interface de dimerização. A análise comparativa entre Gal-1c e Gal-1h mostrou que estas substituições conferem a Gal-1c um caráter mais polar, com consequente aumento da distribuição de volume molecular. Nos ensaios de hemaglutinação, pode-se observar que é necessária uma concentração 2 vezes maior de Gal-1c para aglutinar eritrócitos humanos, de carneiro e de coelho na mesma proporção que a Gal-1h. Por meio do glycan array, pode-se determinar o perfil de ligação a glicanas de ambas as Gal-1. As duas Gal-1 apresentam afinidade por glicanas ramificadas contendo galactose terminal, e a Gal-1h apresentou maior intensidade de ligação às glicanas quando comparada à Gal-1c. Preparações de Gal-1c e Gal-1h induzem níveis semelhantes de exposição de FS na superfície de neutrófilos deficientes ou não de Mac-1, sugerindo que a interação Gal-1/Mac-1 não esteja envolvida no processo de exposição de FS na superfície de neutrófilos ativados. Assim, a diferença sequencial entre a Gal-1c e a Gal-1h é capaz de gerar diferenças estruturais consideráveis que implicam no reconhecimento diferencial de glicanas, o que, entretanto, não se reflete na capacidade de indução de FS na superfície de neutrófilos ativados. Além disso, a interação Gal-1/Mac-1 parece não participar desse processo, o que pode indicar que o papel da Gal-1 no turnover de neutrófilos, via reconhecimento fagocítico, seja um processo complexo e independente dessa interação. / Galectin-1 (Gal-1) is a homodimeric and multifunctional lectin that recognizes and binds to beta-galactoside by a carbohydrate recognition domain (CRD). Human Gal-1 (hGal-1) and mouse Gal-1 (mGal-1) are 88.15% identical, and although there are no mutations in key amino acids within the CRD, there are differences in the amino acids sequence near the CRD. Given the potential of these differences to alter overall structure and function, and the common utilization of murine models to study Gal-1 function, we sought to directly compare key biochemical features of hGal and mGal-1. Thus, we performed crystallization and structure determination assays of mGal-1, and determined the carbohydrate binding specificy of mGal-1 and hGal-1 using a glycan array and using hemagglutination assay. We also evaluated the ability of both Gal-1 to induce exposure of phosphatidylserine (PS) in activated neutrophils from the bone marrow of normal or ?-2 integrin (Mac-1) deficient mice, in order to investigate the involvement of Gal-1/Mac-1 interaction in this process. To accomplish this, homogeneous and active preparations of hGal-1 and mGal-1 were used in the study. mGal-1 crystals were obtained in 20% polyethylene glycol 3350 and 0.2 M ammonium fluoride. Data from X-ray diffraction were collected and processed, yielding a structure with a final resolution of 2.4 Å. The amino acid substitutions found between mGal-1 and hGaI-1 are detected on the solvent-exposed surfaces where the CRDs are located and not on the proteins dimerization surfaces. A comparative structural analysis between mGal-1 and hGal-1 shows that these amino acid substitutions confer to mGal-1 a greater number of ionizable residues, polar character, appearance of the acid regions clustered, and a slight increase of volume distribution. In hemagglutination assays, twice the concentration of mGal-1 was required to cause equivalent agglutination of human, sheep or rabbit erythrocytes as hGal-1. Glycan array analysis demonstrated that both galectins have affinity for branched glycans containing terminal galactose residues. However, hGal-1 appeared to display higher levels of binding that mGal-1. Preparations of mGal-1 and hGal-1 induced similar levels of PS exposure on normal or Mac-1 deficient neutrophils, suggesting that the interaction Gal-1/Mac-1 is not involved in this process. Thus, hGal-1 and mGal-1 appear to possess considerable differences in glycan recognition that likely reflects subtle difference in amino acid sequence. Furthermore, the interaction Gal-1/Mac-1 do not appear to participate in this PS exposure process, which suggest that other Gal-1 receptors are likely important in this process.

The master’s thesis deals with proposal of technological process for production of computer case in EMKO Case a.s. Computer case is manufactured from a DX51D + Z275 steel sheet with thickness 1 mm. For manufacturing were chosen technology punching and press-brake bending as the best technologies. Master’s thesis contains literary studies of these chosen technologies. Based on literary studies were made technological calculations, proposal of technological process and choice of machines. For punching was chosen machine TRUMPF TruPunch 2000, for press-brake bending hydraulic machine TRUMPF TrumaBend 50V. For chosen solution is made technical and economical evaluation.

This diploma thesis deals with the evaluation of a security solution that was recently deployed by a British company renting office space. This validation system is based on a database of MAC addresses, a database of clients and active filtering of connected devices. The first part explains the concepts of computer network, VLAN and basic concepts needed to understand the function of dynamic assignment of VLAN and IP addresses. The second part is devoted to measurements based on hypotheses, according to which measures are proposed in the last part to solve these security problems.