Tesis sobre el tema "Canaux auxiliares"
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Proy, Julien. "Sécurisation systématique d'applications embarquées contre les attaques physiques". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEE048.
Texto completoThe security of embedded systems containing sensitive data has become a main concern. These widely deployed devices are subject to physcial attacks, requiring protections both in hardware and software. The race for higher productivity and shorter time to market in the deployment of secure systems pushes for automatic solutions. This thesis studies the integration of software countermeasures against fault attacks in development tools, with a special focus on the compiler. The goal is to enable the automatic application, at compilation time, of a wide range of countermeasures. We propose two protection schemes against these attacks which can be automatically deployed: one scheme dedicated to loop control flow and the second dedicated to the protection of the call graph. These schemes, integrated in the LLVM compiler framework, allow to focus security application on sensitive areas of the targeted code, thus limitating the overhead. Faults that can be exploited are different from a device to another, we thus also provide an ISA-level characterization of fault effects on a superscalar processor representative of mobile phones. This work highlights the need of studying fault effects on more complex platforms, leading to the design of new protection schemes and automating their compilation-time application
Houssein, Meraneh Awaleh. "Enhancing the security of industrial cyber-physical systems trough side-channel leakage". Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2024. http://www.theses.fr/2024IMTA0402.
Texto completoIndustrial cyber-physical systems(ICPSs) have increased in industrial processes.These systems facilitate automation and operational control through physical devices, resource constrained sensors and actuators, digital software, and network connectivity. Although ICPSs have proven effective in improving efficiency levels, they are susceptible to cyber-attacks that could cause significant harm. This thesis aims to enhance the security of ICPS by using side-channel leakage. This research focuses on two key aspects. Firstly, this thesis provides effective and efficient methods to detect and mitigate anomalies in ICPS by using side-channel leakage, ensuring these systems' security and proper functioning. The study proposes a new real-time sound-based anomaly detection approach called SADIS for early and accurate detection of anomalies in ICPS. The SADIS approach addresses the limitations faced by existing methods in detecting anomalies in ICPS, including high detection time, low detection accuracy, and poor robustness to noisy data. SADIS is robust against background noise and transferable to various industrial environments, making it suitable for widespread deployment. Secondly, the thesis studies the resistance of lightweight cryptography algorithms commonly implemented in resource-constrained components of industrial systems, including sensors, actuators, and RFID devices, against side-channel analysis. We propose a theoretical attack on the Elephant algorithm's linear feedback shift registers (LFSR), a finalist in the NIST lightweight cryptography competition. By exploiting the dependence on the secret key, we demonstrate how side-channel analysis can compromise the security of Elephant. We explore possible tweaking to the Elephant algorithm as counter measures against such attacks
Goyet, Christopher. "Cryptanalyse algébrique par canaux auxiliaires". Paris 6, 2012. http://www.theses.fr/2012PA066329.
Texto completoAlgebraic Side Channel Attacks (ASCA) are a new kind of attack presented at CHES2009 by Renauld and Standaert. They showed thatside-channel information leads to effective algebraic attacks, butthese results are mostly experiments strongly based on a SAT-solver. In this talk, we will present a theoretical study which explains andcharacterizes the algebraic phase of these attacks. We study a moregeneral algebraic attack based on Grobner basis methods. We show thatthe complexity of the Grobner basis computations in these attacksdepends on a new notion of algebraic immunity that we define, and onthe distribution of the leakage information of the cryptosystem. Weillustrate this analysis by two examples of attacks on block-ciphersAES and PRESENT with usual leakage models: the Hamming weight and theHamming distance models. Finally, a new criterion for effectivealgebraic side channel attacks is defined. This easily computablecriterion unifies both SAT and Grobner attacks. This criterion alsorestricts the choice of resisting S-Box against ASCA. At CHES 2009, Renauld, Standaert and Veyrat- Charvillon introduced a new kind of attack called algebraic side-channel attacks (ASCA). They showed that side-channel information leads to effective algebraic attacks. These results are mostly experiments since strongly based on the use of a SAT solver. This article presents a theoretical study to explain and to characterize the algebraic phase of these attacks. We study more general algebraic attacks based on Gröbner meth- ods. We show that the complexity of the Gröbner basis com- putations in these attacks depends on a new notion of alge- braic immunity defined in this paper, and on the distribution of the leakage information of the cryptosystem. We also study two examples of common leakage models: the Hamming weight and the Hamming distance models. For instance, the study in the case of the Hamming weight model gives that the probability of obtaining at least 64 (resp. 130) linear relations is about 50% for the substitution layer of PRESENT (resp. AES). Moreover if the S-boxes are replaced by functions maximizing the new algebraic immunity criterion then the algebraic attacks (Gröbner and SAT) are intractable. From this theoretical study, we also deduce an invariant which can be easily computed from a given S-box and provides a suffi- cient condition of weakness under an ASCA. This new invari- ant does not require any sophisticated algebraic techniques to be defined and computed. Thus, for cryptographic engi- neers without an advanced knowledge in algebra (e. G. Gröb- ner basis techniques), this invariant may represent an inter- esting tool for rejecting weak S-boxes. We describe a lattice attack on DSA-like signature schemes under the assumption that implicit infor- mation on the ephemeral keys is known. Inspired by the implicit oracle of May and Ritzenhofen presented in the context of RSA (PKC2009), we assume that the ephemeral keys share a certain amount of bits without knowing the value of the shared bits. This work also extends results of Leadbitter, Page and Smart (CHES2004) which use a very similar type of partial information leakage. By eliminating the shared blocks of bits between the ephemeral keys, we provide lattices of small dimension (e. G. Equal to the number of signatures) and thus obtain an efficient attack. More precisely, by using the LLL algorithm, the complexity of the attack is polynomial. We show that this method can work when ephemeral keys share certain amount of MSBs and/or LSBs, as well as contiguous blocks of shared bits in the middle. Under the Gaussian heuristic assumption, theoretical bounds on the number of shared bits in function of the number of signed messages are proven. Experimental results show that we are often able to go a few bits beyond the theoretical bound. For instance, if only 2 shared LSBs on each ephemeral keys of 200 signed messages (with no knowledge about the secret key) then the attack reveals the secret key. The success rate of this attack is about 90% when only 1 LSB is shared on each ephemeral keys associated with about 400 signed messages
Dugardin, Margaux. "Amélioration d'attaques par canaux auxiliaires sur la cryptographie asymétrique". Thesis, Paris, ENST, 2017. http://www.theses.fr/2017ENST0035/document.
Texto completo: Since the 1990s, side channel attacks have challenged the security level of cryptographic algorithms on embedded devices. Indeed, each electronic component produces physical emanations, such as the electromagnetic radiation, the power consumption or the execution time. Besides, these emanations reveal some information on the internal state of the computation. A wise attacker can retrieve secret data in the embedded device using the analyzes of the involuntary “leakage”, that is side channel attacks. This thesis focuses on the security evaluation of asymmetric cryptographic algorithm such as RSA and ECC. In these algorithms, the main leakages are observed on the modular multiplication. This thesis presents two attacks targeting the modular multiplication in protected algorithms, and a formal demonstration of security level of a countermeasure named modular extension. A first attack is against scalar multiplication on elliptic curve implemented with a regular algorithm and scalar blinding. This attack uses a unique acquisition on the targeted device and few acquisitionson another similar device to retrieve the whole scalar. A horizontal leakage during the modular multiplication over large numbers allows to detect and correct easily an error bit in the scalar. A second attack exploits the final subtraction at the end of Montgomery modular multiplication. By studying the dependency of consecutive multiplications, we can exploit the information of presence or absence of final subtraction in order to defeat two protections : regular algorithm and blinding input values. Finally, we prove formally the security level of modular extension against first order fault attacks applied on elliptic curves cryptography
Dugardin, Margaux. "Amélioration d'attaques par canaux auxiliaires sur la cryptographie asymétrique". Electronic Thesis or Diss., Paris, ENST, 2017. http://www.theses.fr/2017ENST0035.
Texto completo: Since the 1990s, side channel attacks have challenged the security level of cryptographic algorithms on embedded devices. Indeed, each electronic component produces physical emanations, such as the electromagnetic radiation, the power consumption or the execution time. Besides, these emanations reveal some information on the internal state of the computation. A wise attacker can retrieve secret data in the embedded device using the analyzes of the involuntary “leakage”, that is side channel attacks. This thesis focuses on the security evaluation of asymmetric cryptographic algorithm such as RSA and ECC. In these algorithms, the main leakages are observed on the modular multiplication. This thesis presents two attacks targeting the modular multiplication in protected algorithms, and a formal demonstration of security level of a countermeasure named modular extension. A first attack is against scalar multiplication on elliptic curve implemented with a regular algorithm and scalar blinding. This attack uses a unique acquisition on the targeted device and few acquisitionson another similar device to retrieve the whole scalar. A horizontal leakage during the modular multiplication over large numbers allows to detect and correct easily an error bit in the scalar. A second attack exploits the final subtraction at the end of Montgomery modular multiplication. By studying the dependency of consecutive multiplications, we can exploit the information of presence or absence of final subtraction in order to defeat two protections : regular algorithm and blinding input values. Finally, we prove formally the security level of modular extension against first order fault attacks applied on elliptic curves cryptography
Leplus, Gaëtan. "Processeur résistant et résilient aux attaques de fautes et aux attaques par canaux auxiliaires". Electronic Thesis or Diss., Saint-Etienne, 2023. http://www.theses.fr/2023STET0059.
Texto completoIn today's technological landscape, the Internet of Things (IoT) has emerged as a ubiquitous element, yet it brings major security challenges. Fault injection and side-channel attacks are of particular concern, targeting systemic weaknesses and compromising data integrity and confidentiality. Processors, as the cornerstones of computing systems, are crucial in securing the IoT.This thesis focuses on securing the processor pipeline to counter these threats. The significance of this research is highlighted by the need to develop robust security mechanisms at the processor level, the core of all computation and control. Several countermeasures are proposed to enhance the resilience of different parts of the processor against attacks.To secure the data path, an integrity tagging method is proposed. Compatible with traditional masking techniques, this method aims to ensure data integrity throughout the processing pipeline, with minimal overhead.For the instruction path, a mechanism for masking the current instruction is proposed, where a mask is generated based on the previous instruction. This innovative technique enables effective instruction security with very low overhead.Regarding the desynchronization process, it introduces a robust method for inserting dummy instructions more efficiently than current techniques.These countermeasures, by targeting key components of the processor, contribute to a notable improvement in the security of IoT systems. They address the roots of vulnerabilities, thus providing enhanced protection against a wide range of attacks
Fernandes, Medeiros Stéphane. "Attaques par canaux auxiliaires: nouvelles attaques, contre-mesures et mises en oeuvre". Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209096.
Texto completoDoctorat en Sciences
info:eu-repo/semantics/nonPublished
Barthe, Lyonel. "Stratégies pour sécuriser les processeurs embarqués contre les attaques par canaux auxiliaires". Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20046/document.
Texto completoSide-channel attacks such as differential power analysis (DPA) and differential electromagnetic analysis (DEMA) pose a serious threat to the security of embedded systems. The aim of this thesis is to study the side-channel vulnerabilities of software cryptographic implementations in order to create a new class of processor. For that purpose, we start by identifying the different elements of embedded processors that can be exploited to reveal the secret information. Then, we introduce several strategies that seek a balance between performance and security to protect such architectures at the register transfer level (RTL). We also present the design and implementation details of a secure processor, the SecretBlaze-SCR. Finally, we evaluate the effectiveness of the proposed solutions against global and local electromagnetic analyses from experimental results obtained with a FPGA-based SecretBlaze-SCR. Through this case study, we show that a suitable combination of countermeasures significantly increases the side-channel resistance of processors while maintaining satisfactory performance for embedded systems
Vaquié, Bruno. "Contributions à la sécurité des circuits intégrés face aux attaques par canaux auxiliaires". Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20133/document.
Texto completoSide channel attacks such as power analysis attacks are a threat to the security of integrated circuits.They exploit the physical leakage of circuits during the cryptographic computations to retrieve the secret informations they contain. Many countermeasures, including hardware, have been proposed by the community in order to protect cryptosystems against such attacks. Despite their effectiveness, their major drawback is their significant additional cost in area, speed and consumption. This thesis aims at proposing low cost countermeasures able to reduce the leaks and offering a good compromise between security and costs. First we identify the main sources of leakage of a cryptographic system that integrates an iterative hardware architecture of a symetric algorithm. Then we propose several low cost countermeasures, which aim at reducing this leakage. Finally, we evaluate the robustness of our solutions against side channel attacks
Dosso, Fangan Yssouf. "Contribution de l'arithmétique des ordinateurs aux implémentations résistantes aux attaques par canaux auxiliaires". Electronic Thesis or Diss., Toulon, 2020. http://www.theses.fr/2020TOUL0007.
Texto completoThis thesis focuses on two currently unavoidable elements of public key cryptography, namely modular arithmetic over large integers and elliptic curve scalar multiplication (ECSM). For the first one, we are interested in the Adapted Modular Number System (AMNS), which was introduced by Bajard et al. in 2004. In this system of representation, the elements are polynomials. We show that this system allows to perform modular arithmetic efficiently. We also explain how AMNS can be used to randomize modular arithmetic, in order to protect cryptographic protocols implementations against some side channel attacks. For the ECSM, we discuss the use of Euclidean Addition Chains (EAC) in order to take advantage of the efficient point addition formula proposed by Meloni in 2007. The goal is to first generalize to any base point the use of EAC for ECSM; this is achieved through curves with one efficient endomorphism. Secondly, we propose an algorithm for scalar multiplication using EAC, which allows error detection that would be done by an attacker we detail
Morante, Daniel Rodrigo Herrra. "Uncaria tomentosa na desinfecção de canais radiculares contaminados por patógenos endodônticos". UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2010. http://tede2.uepg.br/jspui/handle/prefix/1762.
Texto completoThe aim of this in vitro study was to evaluate antimicrobial activity of four auxiliary substances against Enterococcus faecalis, Staphylococcus aureus and Candida albicans, commonly isolated microorganisms in endodontic failure cases, on which was tested: 2% chlorhexidine gel (CHX), 2% Uncaria tomentosa gel (UG), 2% CHX gel and UG in equal parts (1:1) (CHX + UG) and Natrosol (NAT). Firstly, the agar diffusion method was used; the inhibition halos were measured and significance was determined using ANOVA and Tukey`s test (p <0.05). The more effective auxiliary substance against E. faecalis and C. albicans was CHX + UG, followed by CHX and UG. Against S. aureus, CHX+UG had a similar effect to that shown by CHX and UG.The NAT group had not effect against any microorganism. Secondly was evaluating antimicrobial activity of auxiliary substances in infected dentin. It was used a total of 120 pre-molars, which were divided for each organism into 4 groups (n = 10). Microbiological samples were collected before the chemomechanical preparation (PQM) (S1), after PQM (S2) and after 7 days of intracanal medication (MIC) for each group (S3). The count of colony forming units (CFU/mL) was statistically analyzed by Kruskal-Wallis and Mann-Whitney test (p <0.05). In S2, all groups showed a significant reduction of CFU/mL compared with S1 In groups CHX, CHX+UG and UG there was no CFU/mL. In S3, specimens contaminated with E. faecalis of the CHX and NAT groups had significantly higher microbial load compared with S2, but CHX+UG group kept the value obtained in S2, similar to that obtained by UG group. Specimens contaminated with S. aureus and C. albicans of the CHX, CHX+UG and UG groups remained the negative values of S2. With results obtained it was concluded, that the association CHX+UG has the ability to inhibit microbial growth of E. faecalis and C. albicans higher than shown by CHX and UG. Against S. aureus, CHX and UG had a similar effect. It was also found that CHX, CHX+UG and UG were effective in disinfecting the canal after PQM, but only after 7 days the groups that received CHX+UG and UG as MIC, remained root canals free of CFU of E. faecalis. Thus, UG alone or in combination with CHX, was effective in disinfecting root canals.
O objetivo deste estudo foi avaliar, por meio de testes in vitro, o potencial antimicrobiano de quatro substâncias auxiliares sobre microrganismos comumente isolados nos casos de insucesso do tratamento endodôntico, Enterococcus faecalis, Staphylococcus aureus e Candida albicans; Foram testados: gel de digluconato clorexidina a 2% (CHX), gel de Uncaria tomentosa a 2% (UG), gel de CHX e UG a 2% em partes iguais (1:1) (CHX+UG) e Natrosol (NAT). Primeiramente foi utilizado o método de difusão em ágar. Os valores coletados pela mensuração dos halos de inibição foram analisados estatisticamente com ANOVA de um critério e o teste de Tukey (p<0,05). A substância auxiliar que mostrou-se mais efetiva sobre E. faecalis e C. albicans foi CHX+UG , seguida da CHX e UG. Frente a S. aureus, CHX+UG apresentou um efeito semelhante ao mostrado pela CHX e UG. O Grupo NAT não mostrou capacidade de inibição sobre nenhum dos microrganismos. A segunda parte do estudo visou avaliar a capacidade antimicrobiana das sustâncias auxiliares em dentina contaminada. Foi utilizado um total de 120 pré-molares inferiores distribuídos em 4 grupos para cada microrganismo (n=10). Foram feitas coletas microbiológicas antes do preparo químico-mecânico (PQM) (S1), após PQM (S2), e após 7 dias com medicação intracanal (MIC) (S3). A contagem das unidades formadoras de colônia (UFC/mL) foi analisada estatisticamente pelo teste de Kruskal-Wallis e teste de Mann-Whitney (p<0,05). Em (S2), todos os grupos apresentaram uma redução significativa de UFC/mL em comparação com S1. Nos grupos CHX, UG e CHX+UG não houve a presença de UFC/mL; para S3, os espécimes contaminados com E. faecalis dos grupos CHX e NAT apresentaram carga microbiana significativamente maior à apresentada em S2; porém o grupo CHX+UG manteve o valor obtido em S2, valor que foi semelhante ao obtido pelo grupo UG. Os espécimes contaminados com S. aureus e C. albicans dos grupos CHX, UG e CHX+UG mantiveram os valores negativos de S2, assim não apresentaram UFC/mL. Concluiu-se que a associação CHX+UG apresenta capacidade de inibição do crescimento microbiano sobre E. faecalis e C. albicans superior ao mostrado por CHX e UG. Frente a S. aureus, CHX e UG apresentaram efeito semelhante. Concluiu-se também que CHX, UG e CHX+UG foram eficazes na desinfecção do canal após PQM, porém após 7 dias só os grupos que receberam CHX+UG e UG como MIC, mantiveram os canais livres de UFC de E. faecalis. Assim, UG só ou em associação com CHX, se mostrou eficaz na desinfecção de canais radiculares.
Rodrigues, Evaldo Almeida. "Avaliação da capacidade de remoção da camada residual dentinária com o uso do Endo PTC em diferentes formulações, associado a duas concentrações de hipoclorito de sódio, utilizando ou não irrigação final com EDTA". Programa de Pós- Graduação em Odontologia da UFBA, 2010. http://www.repositorio.ufba.br/ri/handle/ri/10540.
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A ação dos instrumentos nas paredes do canal radicular proporciona a formação da camada residual, que é um extrato de matéria orgânica e inorgânica, de aparência amorfa, superfície irregular e granulosa que é depositada na superfície dentinária a medida que vai se formando, e quando não é removida pode interferir no selamento almejado na etapa da obturação. Algumas substâncias químicas com diferentes composições e variadas concentrações são utilizadas isoladas ou em associações para remover esta camada residual. O presente estudo buscou analisar in vitro, através de Microscopia Eletrônica de Varredura, a eficácia na remoção da camada residual, de diferentes formulações de Endo PTC quando associadas a diferentes concentrações de hipoclorito de sódio, utilizando ou não, irrigação final com EDTA. Para tanto, foram utilizados oitenta dentes unirradiculares humanos recém-extraídos, divididos aleatoriamente em oito grupos de dez dentes cada e distribuídos de acordo com as substâncias utilizadas na instrumentação, da seguinte maneira: Grupo I – preparo do canal com Endo PTC creme, associado ao hipoclorito sódio a 1%; Grupo II – preparo do canal como Endo PTC creme, associado ao hipoclorito de sódio a 2,5%; Grupo III – preparo do canal com Endo PTC creme associado ao hipoclorito de sódio a 1% e irrigação final com EDTA a 17%; Grupo IV – preparo do canal com Endo PTC creme associado ao hipoclorito de sódio a 2,5 e irrigação final com EDTA a 17%. Nos Grupos V, VI, VII e VIII foram utilizadas as mesmas substâncias dos grupos I, II, III e IV respectivamente, substituindo o Endo PTC creme pelo Endo PTC Leve. Os resultados mostraram que: a irrigação final com EDTA promove uma melhor remoção da camada residual, independente da concentração do hipoclorito de sódio e da formulação do Endo PTC; de um modo geral as formulações do Endo PTC não apresentam diferenças estatisticamente significantes na remoção da camada residual independente da concentração do hipoclorito de sódio; a concentração do hipoclorito de sódio associado ao Endo PTC creme, não interfere estatisticamente na remoção da camada residual; a concentração do Hipoclorito de sódio associado ao Endo PTC Leve apresentou diferença estatisticamente significante quando foi feita a irrigação final com EDTA, sendo que a 2,5 % apresentou melhores resultados; no terço apical quando foi utilizado hipoclorito de sódio a 1% e foi feita irrigação final com EDTA, a remoção da camada residual foi estatisticamente inferior ao terço cervical independente da formulação do Endo PTC.
Salvador
Geib, Sandrine. "Mécanismes de régulation des canaux calcium sensibles au potentiel par les sous-unités auxiliaires béta". Aix-Marseille 2, 2002. http://www.theses.fr/2002AIX20661.
Texto completoMartinelli, Jean. "Protection d'algorithmes de chiffrement par blocs contre les attaques par canaux auxiliaires d'ordre supérieur". Versailles-St Quentin en Yvelines, 2011. http://www.theses.fr/2011VERS0043.
Texto completoTraditionally, a cryptographic algorithm is estimated through its resistance to "logical" attacks. When this algorithm is implanted within a material device, physical leakage can be observed during the computation and can be analyzed by an attacker in order to mount "side channel" attacks. The most studied side channel attack is the differential power analysis (DPA). First order DPA is now well known and can be prevented by securely proven countermeasures. In 2008, some results are known for second order, but none for third order. The goal of this thesis is to propose a frame for k-th order DPA where k>1. We developed several masking schemes as alternatives to the classical ones in order to propose a better complexity-security ratio. These schemes make use of various mathematical operations such as field multiplication or matrix product and cryptographic tools as secret sharing and multi-party computation. We estimated the security of the proposed schemes following a methodology using both theoretical analysis and practical results. At last we proposed an evaluation of the action of the word size of a cryptographic algorithm upon its resistance against side channel attacks, with respect to the masking scheme implemented
Bichet, Delphine. "Régulation fonctionnelle des canaux calcium sensibles au potentiel par la sous-unité auxiliaire β". Aix-Marseille 2, 2000. http://www.theses.fr/2000AIX22061.
Texto completoThillard, Adrian. "Contre-mesures aux attaques par canaux cachés et calcul multi-parti sécurisé". Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEE053/document.
Texto completoCryptosystems are present in a lot of everyday life devices, such as smart cards, smartphones, set-topboxes or passports. The security of these devices is threatened by side-channel attacks, where an attacker observes their physical behavior to learn information about the manipulated secrets. The evaluation of the resilience of products against such attacks is mandatory to ensure the robustness of the embedded cryptography. In this thesis, we exhibit a methodology to efficiently evaluate the success rate of side-channel attacks, without the need to actually perform them. In particular, we build upon a paper written by Rivainin 2009, and exhibit explicit formulaes allowing to accurately compute the success rate of high-order side-channel attacks. We compare this theoretical approach against practical experiments. This approach allows for a quick assessment of the probability of success of any attack based on an additive distinguisher. We then tackle the issue of countermeasures against side- channel attacks. To the best of our knowledge, we study for the first time since the seminal paper of Ishai, Sahai and Wagner in 2003 the issue of the amount of randomness in those countermeasures. We improve the state of the art constructions and show several constructions and bounds on the number of random bits needed to securely perform the multiplication of two bits. We provide specific constructions for practical orders of masking, and prove their security and optimality. Finally, we propose a protocolallowing for the private computation of a secure veto among an arbitrary large number of players, while using a constant number of random bits. Our construction also allows for the secure multiplication of any number of elements of a finite field
Rosa, Nicolas. "Rôle des sous-unités auxiliaires des canaux calciques Cav1 dans les lymphocytes Th2 : implications thérapeutiques dans l'asthme allergique". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30359/document.
Texto completoCalcium channels include store-operated (ORAI) and voltage-gated (Cav) channels that are considered to be important for calcium entry in non-excitable and excitable cells, respectively. Voltage-gated calcium channels such as Cav1 are essential for excitable cell function, including neuronal transmission, muscle contraction or hormone secretion. However, numerous studies show that Cav1 channels are expressed in non-excitable cells as well, and are important for T cell effector functions. Cav1 channels are composed of the a1 subunit forming the ion pore and auxiliary subunits ß and a2δ. These subunits are important for the electric activity of the channel but also for its regulation, its stability and its expression at the plasma membrane in excitable cells. Our group clearly identified the a1 subunit of Cav1.2 and Cav1.3 channels as essential for the function of Th2 lymphocytes, a T cell subset responsible for allergic diseases. Pharmacological and genetic inhibition of these channels significantly reduces the expression of cytokines in mouse Th2 cells, but not in Th1 cells. The goal of my work was to understand whether the auxiliary subunits of Cav channels, particularly the ß subunit, are necessary for the function of Cav1 channels in Th2 lymphocytes that are not excitable cells. We used antisense oligonucleotides targeting all ß subunits to reduce the expression of ß1 and ß3, the two subunits expressed in Th2 lymphocytes. Transfection of murine and human Th2 with these oligonucleotides decreases TCR-dependent calcium influx and cytokine expression. In addition, the effect of the Cavß antisense oligonucleotides seems to result from the loss of expression of the a1 subunit, as similarly described in neurons. In addition, the use of shRNA specific to ß1 and ß3 in mouse Th2 shows a critical role the ß1 subunit in the functional response of Th2 lymphocytes. Finally, the Cavß antisense oligonucleotides reduce the airway inflammation in an allergic asthma model in mice, as well as a pharmacological inhibitor of a2δ subunits. This work has identified auxiliary subunits of Cav channels as new potential therapeutic targets in allergic diseases such as asthma
Reynaud, Léo. "Contributions à l’analyse de canaux auxiliaires sans connaissance des clairs et chiffrés, et à la recherche de S-boxes compactes". Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0107.
Texto completoCryptography is widely used nowadays, and side channel attacks are known threats. In order to develop suitable countermeasures, these attacks are constantly studied and improved. This document is part with this approach and studies joint distributions attacks which do not need the plaintext nor the ciphertext, contrary to classical attacks. First, new variants which improve this attack are proposed. They mainly consist in observing more or different intermediate variables, and adapt theoretical distributions accordingly. Then, a practical experiment is done on a microcontroller which validates the attack apart from simulations. Finally, several solutions that compromise masked implementations are proposed. They consist in using the fact that some masks are reused on several internal variables, ending in the quadrivariate attacks proposal. An other main theme about 8 bits S-boxes construction is explored in this document, and originated from the participation to the PACLIDO project which aims to develop a lightweight cryptography algorithm. The S-box is a critical component of cryptographic algorithms and acts to make them resilient to classical cryptanalysis. Unfortunately, this component is often costly in terms of logical gates. We propose two methods for searching compact 8 bit circuits composed of hybrid gates ANDXOR, and show some results close to the literature
Santos, Regis Burmeister dos. "Análise histológica dos tecidos periapicais de dentes de cães como recurso para avaliar a influência dos auxiliares químicos da instrumentação no selamento dos canais radiculares obturados com RealSeal® e expostos ao meio bucal". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/132737.
Texto completoThe aim of this study was to assess the influence of the cleaning protocol on sealing of root canal obturation with RealSeal following post space preparation, by means of periapical tissue response analysis. 1% sodium hypochlorite and 2% chlorhexidine were the tested products. For this purpose, six dogs were used, 10 teeth in each dog, comprising a total of 60 teeth and 120 root canals, were randomly divided into seven groups, being three test groups, three negative controls and a positive control. Following obturation, all teeth were kept totally sealed during 24 hours to allow sealer setting. Then the positive control and the three test groups had their seal removed, and obturation material exposed to the oral environment for 90 days. Negative controls were kept sealed during the whole experimental period. The animals were killed and their mandibles removed. Histological procedures were adopted as to HE staining. Optical histological analysis at magnifications varying from 25x to 400x considered the periapical tissue status at various sites by a blinded senior observer. Non-parametric Kruskal-Wallis and a Mann-Whitney and Willcoxon post-hoc were adopted at α= 0.05. Experimental groups and negative control had lower degree of inflammation when compared with the positive control, which showed consistently neutrophil and eosinophil infiltrates and areas of abscess (p=0.001). Both sodium hypochlorite and chlorhexidine behaved similarly, not interfering with the periapical tissue response. The remaining filling material was efficient to seal the apical portion of the root canal, regardless of the cleaning protocol.
Ayala, Aurélio. "La North-West Mounted Police canadienne et ses auxiliaires métis, 1874-1900 : une relation d'interdépendance ?" Thesis, Nantes, 2017. http://www.theses.fr/2017NANT2028/document.
Texto completoIn 1873, the Canadian government founded the Mounted Police to assert its sovereignty on the Western plains, to prepare Euro-Canadian settlement and to control First Nations and the Metis. This colonial policy triggered the resistance of the Metis, who took up arms in 1885 to defend their territory and political rights. This thesis is based on original sources from the police archives. They reveal the existence of an on-going cooperation of some Metis, from the arrival of the police on indigenous territory in 1874 until the end of the century at least. This thesis aims at understanding why the police hired these Metis during its takeover of the West and the first contacts with Indigenous peoples, as well as throughout the implementation of its colonial mission, even after the Metis uprising of 1885. Through cooperation with the police, the auxiliaries tried to mitigate the negative effects of colonialism by making economic, social and political gains. The auxiliaries provided the police with the social and cultural capital it needed – their knowledge of aboriginal languages, cultures and environment – to implement its missions in an unfamiliar territory. In return, the police provided salaries and supply contracts as well as its own military and judicial help. The police and its auxiliaries relied on each other in this interdependent relationship. This research has shown that the auxiliaries formed socio-familial networks who were loyal to Canada, which helped the police hire trustworthy men. Nevertheless, this cooperation also stems from the auxiliaries’ agency since they shared the economic capital obtained from the police through their social networking practices
Moignot, Bénédicte. "Caractérisation des sous-unités principales et auxiliaires des canaux sodium dépendant du potentiel exprimées dans le système nerveux central de l'insecte periplaneta americana". Phd thesis, Université d'Angers, 2010. http://tel.archives-ouvertes.fr/tel-00491350.
Texto completoOliveira, Ana Carolina Mascarenhas 1982. "Efetividade in vitro de substâncias químicas auxiliares e medicações intracanais sobre microrganismos e endotoxina em canais radiculares". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290432.
Texto completoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo deste estudo foi avaliar in vitro a efetividade de substâncias químicas auxiliares (SQA) e medicações intracanais (MIC) sobre microrganismos e endotoxina em canais radiculares. Dentes humanos extraídos unirradiculares (n=520) foram raspados e seccionados, tendo suas coroas descartadas e as raízes padronizadas no comprimento de 15 mm. As raízes foram armazenadas em solução fisiológica (NaCl 0,9%) (SF) estéril e congeladas em freezer a -20ºC até sua utilização. As 520 raízes foram impermeabilizadas, instrumentadas, incluídas em placas de poliestireno, esterilizadas por gás de óxido de etileno e inoculadas com E. faecalis, E. coli e C. albicans durante 28 dias. Dentre as 520 raízes, 400 foram utilizadas para análise microbiológica (identificação fenotípica/molecular) e quantificação de endotoxinas pelo teste LAL (Lisado do amebócito de Limulus). Para tanto, coletas foram realizadas em diferentes momentos da fase de PQM e do uso de MIC: 7, 14 e 30 dias. As quatrocentas raízes foram divididas aleatoriamente em grupos e instrumentadas de acordo com a SQA utilizada durante o preparo químicomecânico (PQM) com (n=360) ou sem (n=40) o uso de EDTA 17%, respectivamente: hipoclorito de sódio (NaOCl) 5,25% (n=90/10), clorexidina 2% gel (CLG 2%) (n=90/10), NaOCl 5,25% e irrigação com CLL 2% (clorexidina líquida) (n=90/10) e SF (controle) (n=90/10). Em seguida, as raízes irrigadas com EDTA 17% foram divididas em grupos de acordo com a MIC utilizada: CLG 2% (n=90), hidróxido de cálcio (HC) + CLG 2% (n=90), HC + SF (9:1) (n=90) e SF (controle) (n=90). Demais raízes (n=120) foram submetidas a diferentes SQA e MIC, sendo analisadas por meio de microscopia confocal quanto à viabilidade microbiana. Os dados foram submetidos à análise estatística em nível de significância de 5%. Observou-se que PQM com CLG 2%, NaOCl 5,25% e NaOCl 5,25% seguido de irrigação final com CLL 2% promoveu redução de E. coli, E. faecalis, C. albicans e endotoxina de E. coli. Após sete dias do PQM, observou-se reinfecção do canal radicular. CLG 2%, NaOCl 5,25%, NaOCl 5,25% seguido de irrigação com CLL 2%, HC + SF, e HC + CLG 2% não demonstraram capacidade de eliminar endotoxina de E. coli. Concluiu-se que CLG 2%, NaOCl 5,25%, NaOCl 5,25% seguido de irrigação com CLL 2%, HC + SF, e HC + CLG 2% foram efetivos na redução de E. coli, E. faecalis e C. albicans. Menor redução microbiana ocorreu nos túbulos dentinários comparada à luz do canal radicular. Nenhuma substância foi capaz de eliminar endotoxina de E. coli
Abstract: The aim of this study was to evaluate in vitro the effectiveness of the auxiliary chemical substances and intracanal medications on microorganisms and endotoxins in root canals. Single-rooted extracted human teeth (n=520) were scraped and sectioned, and their crowns discarded. The roots were standarded at 15 mm and stored in sterile saline at -20ºC until use. They (n=520) were externally waterproof, endodontically instrumented, included in microtiter plates, sterilized by ethylene oxide gas and inoculated with E. faecalis, E. coli, and C. albicans for 28 days. Among the 520 roots, 400 were used for microbiological assay (phenotypic/molecular identification) and endotoxin assay by LAL test (Limulus amebocyte Lysate). Samples were collected at different times on CMP and intracanal medication: 7, 14 and 30 days. Four hundred roots were randomly divided into groups and instrumented according to the auxiliary chemical substances used during chemomechanical preparation (CMP) with (n=360) or without (n=40) 17% EDTA, respectively: 5.25% sodium hypochlorite (NaOCl) (n=90/10); 2% chlorhexidine gel (CLG) (n=90/10); 5.25% NaOCl and final irrigation with 2% CLL (n=90/10); and saline (control) (n=90/10). The roots irrigated with 17% EDTA were divided into subgroups according to intracanal medication: 2% CLG (n=90); calcium hydroxide (CH) plus 2% CLG (n=90); CH plus saline (9:1) (n=90); and saline (control) (n=90). Another roots (n=120) were submitted to different auxiliary chemical substances and intracanal medications and analyzed by confocal microscopy regarding microbial viability. The results were statistically analyzed at 5% significance level. CMP with 2% CLG, 5.25% NaOCl, and 5.25% NaOCl plus 2% CLL promoted reduction of E. coli, E. faecalis, C. albicans and endotoxin levels. Seven days after CMP, the root canals were re-infected. 2% CLG, 5.25% NaOCl, 5.25% NaOCl plus 2% CLL, CH, and CH plus 2% CLG showed no ability on endotoxin elimination. It was concluded that 2% CLG, 5.25% NaOCl, 5.25% NaOCl plus 2% CLL, CH, and CH plus 2% CLG was effective on reducing E. coli, E. faecalis, and C. albicans. Lower microbial reduction occurred in the dentinal tubules compared to the root canal. No substance was able to eliminate endotoxin
Doutorado
Endodontia
Doutora em Clínica Odontológica
Battistello, Alberto. "On the security of embedded systems against physical attacks". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV047/document.
Texto completoThe subject of this thesis is the security analysis of cryptographic implementations. The need for secure communications has always been a primary need for diplomatic and strategic communications. Cryptography has always been used to answer this need and cryptanalysis have often been solicited to reveal the content of adversaries secret communications. The advent of the computer era caused a shift in the communication paradigms and nowadays the need for secure communications extends to most of commercial and economical exchanges. Modern cryptography provides solutions to achieve such new security goals but also open the way to a number of new threats. It is the case of fault and side-channel-attacks, which today represents the most dangerous threats for embedded cryptographic implementations. This thesis resumes the work of research done during the last years as a security engineer at Oberthur Technologies. Most of the results obtained have been published as research papers [9,13-17] or patents [1-6]. The security research goals of companies around the world working in the embedded domain are twofold. The security engineer has to demonstrate the ability to correctly evaluate the security of algorithms and to highlight possible threats that the product may incur during its lifetime. Furthermore it is desirable to discover new techniques that may provide advantages against competitors. It is in this context that we present our work.This manuscript is divided into four main chapters.The first chapter presents an introduction to various mathematical and computational aspects of cryptography and information theory. We also provide an introduction to the main aspects of the architecture of secure micro-controllers.Afterwards the second chapter introduces the notion of fault attacks and presents some known attack and countermeasure [15-17]. We then detail our work on asymmetric and symmetric infective fault countermeasures as long as on elliptic curves fault attacks [13].The third chapter discusses about side-channels, providing a brief introduction to the subject and to well-known side-channel attacks and countermeasures. We then present two new attacks on implementations that have been considered secure against side channels [9,14]. Afterwards we discuss our combined attack which breaks a state-of-the-art secure implementation [10].Finally, the fourth chapter concludes this works and presents some perspectives for further research.During our investigations we have also found many countermeasures that can be used to thwart attacks. These countermeasures have been mainly published in the form of patents [1-6]. Where possible some of them are presented along with the attack they are conceived to thwart
Smyj, Robert Peter. "Chiral auxiliary design for the stereoselective addition of alpha-alkoxymethyl carbanions to aldehydes and ketones". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ65261.pdf.
Texto completoBruneau, Nicolas. "Attaque par canaux auxillaires multivariées, multi-cibles et d'ordre élevé". Thesis, Paris, ENST, 2017. http://www.theses.fr/2017ENST0025/document.
Texto completoSide Channel Attacks are a classical threat against cryptographic algorithms in embedded systems. They aim at exploiting the physical leakages unintentionally emitted by the devices during the execution of their embedded programs to recover sensitive data. As such attacks represent a real threat against embedded systems different countermeasures have been developed. In thesis we investigate their security in presence of multiple leakages. Indeed there often are in the leakage measurements several variables which can be exploited to mount Side Channel Attacks. In particular we show in this thesis the optimal way to exploit multiple leakages of a unique variable. This dimensionality reduction comes with no loss on the overall exploitable information. Based on this result we investigate further how such dimensionality reduction methodscan be applied in the case of protected implementations. We show that the impact of such methods increases with the security “level” of the implementation. We also investigate how to exploit the leakages of multiplevariables in order to improve the results of Side Channel Analysis. We start by improving the attacks against masking schemes, with a precomputed table recomputation step. Some protections have been developed to protect such schemes. As a consequence we investigate the security provided by these protections. In this context we present results which show that the main parameter to evaluate the security of the masking schemes is not sufficient to estimate the global security of the implementation. Finally we show that in the context of masking scheme with shuffling the optimal attack is not computable. As a consequence we present a truncated version of this attack with a better effectiveness
Masgana, Delphine. "Injection de fautes et de logiciels sur les implémentations cryptographiques". Paris 7, 2012. http://www.theses.fr/2012PA077215.
Texto completoThe cryptography is very widespread inside smartcards or secure devices. These embedded cryptoSystems are proved theoretically secure. Nevertheless, they infère in far or near environment. So active perturbations, named fault analysis, or passive eavesdropping, called side-channel analysis, constitute real threats against hardware and software implementations. This thesis dealts with fault and software injections on cryptographie protocols. The fault analysis and side-channnel analysis give some more information on hardware and software implementations. The internai state of cryptographic computations, secret or private keys or private algorithms are all potential targets of this kind of analysis. In this thesis, a statistical analysis based on fault attack on the carry of Schnorr scheme operations gives access to private key in asymmetric signature or ciphering. Then, code injection in order to monitor memory cache of computer allows one to retrieve secret permutation table for stream cipher RC4, due to timing analysis on cache lines. Then, two differential analysis on internai rounds of AES enable to obtain secret key for the three different AES variants. Finally, a new consequence of fault model, which bypasses one instruction, allows one to take over a host. It is proved that it is important to protect cryptographic implémentations with proper countermeasures against fault analysis and side-channel analysis
Zhao, Juan. "Biophysical characterization of neuronal and skeletal muscle sodium channels, and their regulation by auxiliary beta subunits". Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28793/28793.pdf.
Texto completoVoltage-gated Na channels are responsible for the rising phase of action potentials, and consist of a pore-forming α subunit and one or more auxiliary β subunits. The α subunit alone is sufficient for the functional expression of Na channels, however, β subunits modulate the location, expression and functional properties of α subunits. My thesis will focus on three neuronal Na channels (Nav1.6, Nav1.7 and Nav1.8) and one skeletal muscle Na channel (Nav1.4). Neuronal Na channel are key players in the impulse propagation along axon. Nav1.7 and Nav1.8 are the main Na channels expressed in DRG neurons, and their altered expression and modulation following injury and inflammation play a major role in nociception and chronic pain. Nav1.6 is highly concentrated at nodes of Ranvier, and has a critical role not only in saltatory conduction but also in high-frequency repetitive firing. Skeletal muscle Na channel Nav1.4 is the initiator of muscle contraction. Mutations in Nav1.4 cause skeletal muscle channelopathies. Guiding questions for our investigations were: 1) How do auxiliary β subunits regulate peripheral nerve Na channel Nav1.6 and Nav1.8? 2) What is the underlying biophysical defect of M1476I, a novel founder SCN4A mutation associated with painful cold-induced myotonia in French Canadians? 3) What is the biophysical characterization of the Nav1.6 persistent current? 4) What is the expression pattern of auxiliary subunits, and how do β subunits regulate Nav1.7 in DRG neurons? We addressed these questions by multiple approaches including patch clamp techniques for whole-cell and single-channel recordings in heterologous expression systems; immunohistochemistry, single-cell RT-PCR and immunoprecipitation in DRG neurons. Firstly, we employed single-cell RT-PCR of acutely dissociated DRG neurons to identify the expression of β1-4 subunits in small-diameter sensory neurons. Our results indicated that small-diameter DRG neurons widely expressed Nav1.6 and Nav1.8 channels and β1-β3 subunits. Co-expression studies were used to assess the regulation of Nav1.6 and Nav1.8 by β subunits. The β1 subunit induced a significant increase in the current density of Nav1.8 when co-expressed in HEK293 cells, but had no effect on that of Nav1.6. In addition, the C-terminal domain of β1 was involved in the modulation of Nav1.8 channel based on the results of experiments with β1/β2 chimeras harboring various regions of the strongly regulating β1 together with the weakly regulating β2 subunit. Secondly, we investigated the biophysical defects of M1476I mutation in Nav1.4 channels using whole-cell patch-clamp technique in tsA201 cells. M1476I mutant channel exhibited similar biophysical defects compared with other PAM-causing mutations, including an increased persistent current of Nav1.4, a slower current decay, a positive shift of fast inactivation, and an accelerated recovery from fast inactivation. Lowering the temperature slowed the kinetics for both wide-type and mutant channels, and worsened the defective fast inactivation of M1476I channels by further increasing the amplitude of the persistent current. Mexiletine helps relieve myotonia in M1476I carriers by effectively suppressing the increased persistent current, except for the use-dependent block. However, mexiletine had a reduced effectiveness on the use-dependent block of M1476I channels, and that was associated with a faster recovery from mexiletine block of mutant channels. Thirdly, we characterized the whole-cell and single-channel properties of Nav1.6 persistent currents expressed in HEK293 cells. We noted that Nav1.6 persistent current was highly sensitive to the composition of the internal solution, and persistent current was rarely detectable when CsF instead of CsCl was used. By substituting CsF for CsCl in the intracellular solution, we showed that Nav1.6 persistent current in the whole-cell configuration was 3–5% of the peak transient current. This amplitude of persistent current was similar to the ratio between peak and persistent open probability observed in the single-channel recording, indicating that the occurrence of late channel reopenings accounts for the persistent macroscopic Na current typical of Nav1.6. Finally, we employed a combination of single-cell RT-PCR, immunocytochemistry and immunoprecipitation to investigate subunit expression in subpopulations of sensory neurons. subunits were differentially expressed in small (2, 3) and large (1, 2) DRG neurons. Nav1.7 mRNA was significantly co-expressed with the 2 and 3 subunits in the same population of small-diameter DRG neurons. They formed stable protein-protein interactions and co-localized within the plasma membranes of neurons.When co-expressed in HEK293 cells, 3 and 1 subunits shifted activation and inactivation curves respectively and induced a marked increase in Nav1.7 window current. Our data indicated a preferential expression of subunits in small and large DRG neurons and a subunit-specific Nav1.7 regulation in these subpopulations of sensory neurons.
Tableau d'honneur de la FÉSP
Driffort, Virginie. "Rôle du canal sodique NaV1.5 et de la sous-unité auxiliaire β4 dans l’invasivité des cellules cancéreuses mammaires in vitro et in vivo". Thesis, Tours, 2014. http://www.theses.fr/2014TOUR3310.
Texto completoThe abnormal expression of sodium channel Nav1.5 in breast cancer is correlated with metastatic development and an increased mortality. The Nav1.5 channel is located in invadopodia in human breast cancer cells MDA-MB-231, where it increases proteolytic activity by allosteric modulation of exchanger NHE-1 and activation of acidic proteases. In vivo, in a xenograft model in nude NMRI mice, the expression of Nav1.5 potentiates lung colonization by human breast cancer cells. Metastatic colonization is inhibited by treatment with ranolazine, a pharmacological inhibitor of Nav1.5. The β4 subunit, an auxiliary subunit of Nav channels, is expressed at low levels or lost when tumors are more aggressive, and its suppression in vitro increases celI invasiveness. This increase seems to be independent of Nav1.5 and could be associated with the transition of cells to an amoeboid phenotype. In conclusion, Nav1.5 expression and the loss of β4 expression seem to play complementary roles in the invasiveness of cancer cells
Drujont, Lucile. "Étude de nouveaux acteurs de l'immunité de type 17 à travers l'exploration du rôle des canaux ioniques TMEM176A et B dans les cellules RORγt+". Nantes, 2016. https://archive.bu.univ-nantes.fr/pollux/show/show?id=36471303-ef4e-453c-94a1-59fb808e17a9.
Texto completoThe nuclear hormone receptor RORγt is the key transcription factor that orchestrates the differentiation of Th17 cells but also defines γƠT17 cells and group 3 Innate Lymphoid Cells (ILC3s). We identified TMEM176B, a fourspan transmembrane protein that interacts with its structurally identical homolog protein TMEM176A. Electrophysiological experiments revealed that TMEM176A and B function as cation channels and can heteromerize to exert their function. Strikingy, these two homologs were found among the few direct targets of RORγt. We show that both genes are highly expressed in in vitro-generated mouse Th17 cells compared to Th1, Th2 or iTregs. We also observed that human Th17 cells strongly express TMEM176A and B mRNA, correlating with the level of RORC or IL17A. We further demonstrate that Tmem176a and b are highly expressed in ILC3s and γƠT17 cells. We thus hypothesized that these genes could play a crucial role in the development of a variety of autoimmune diseases dependent on RORγt+ cells. In this regard, Tmem176bdeficient mice were partially but significantly protected from psoriasis-like lesions when compared to control mice. These results suggest that the deletion of both genes may be required to clearly elucidate their role. We have successfully generated a double KO mouse and started to assess the impact of this double deficiency in the steady states as well as in models of inflammation. In parallel, we found that TMEM176A and B protein localizations are strongly linked to the Golgi apparatus, thus highlighting novel potential mechanisms of post-translational modifications or intracellular trafficking in which these cation channels could be involved. We believe that the study of TMEM176A and B will help decipher novel specific pathways of the RORYt+ cell biology that could be therapeutically manipulated
Takarabt, Sofiane. "Évaluation pré-silicium de circuits sécurisés face aux attaques par canal auxiliaire". Electronic Thesis or Diss., Institut polytechnique de Paris, 2021. http://www.theses.fr/2021IPPAT015.
Texto completoEmbedded systems are constantly threatened by various attacks, including side-channel attacks. To guarantee a certain level of security, cryptographic implementations must validate evaluation tests recommended by the certification standards, and thus meet the market needs. For this reason, it is necessary to implement reliable countermeasures to counter this type of attacks. However, once these countermeasures are implemented, verification and validation tests can be very costly in terms of time and money. Thus, optimizing the lifecycle of the circuit, between the design stage and the evaluation stage is paramount. We will explore a very broad class of existing attacks (passive and active), and propose methods of pre-silicon level assessments, allowing on the one hand, to detect the different types of leakages that a given attacker can exploit, and on the other hand, expose different techniques to counter these attacks, while respecting the performance and area aspect. In our analyses, we apply formal and empirical methods to track the impact of each vulnerability on the different abstraction levels of the circuit, and thus propose optimal countermeasures
Bruneau, Nicolas. "Attaque par canaux auxillaires multivariées, multi-cibles et d'ordre élevé". Electronic Thesis or Diss., Paris, ENST, 2017. http://www.theses.fr/2017ENST0025.
Texto completoSide Channel Attacks are a classical threat against cryptographic algorithms in embedded systems. They aim at exploiting the physical leakages unintentionally emitted by the devices during the execution of their embedded programs to recover sensitive data. As such attacks represent a real threat against embedded systems different countermeasures have been developed. In thesis we investigate their security in presence of multiple leakages. Indeed there often are in the leakage measurements several variables which can be exploited to mount Side Channel Attacks. In particular we show in this thesis the optimal way to exploit multiple leakages of a unique variable. This dimensionality reduction comes with no loss on the overall exploitable information. Based on this result we investigate further how such dimensionality reduction methodscan be applied in the case of protected implementations. We show that the impact of such methods increases with the security “level” of the implementation. We also investigate how to exploit the leakages of multiplevariables in order to improve the results of Side Channel Analysis. We start by improving the attacks against masking schemes, with a precomputed table recomputation step. Some protections have been developed to protect such schemes. As a consequence we investigate the security provided by these protections. In this context we present results which show that the main parameter to evaluate the security of the masking schemes is not sufficient to estimate the global security of the implementation. Finally we show that in the context of masking scheme with shuffling the optimal attack is not computable. As a consequence we present a truncated version of this attack with a better effectiveness
Andrade, Júnior Carlos Vieira. "Avaliação in vitro da capacidade seladora e adesiva do AH Plus associado a um sistema adesivo, após o uso de diferentes substâncias químicas auxiliares". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290486.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo deste estudo in vitro foi avaliar o selamento coronário e resistência de união do cimento resinoso AH Plus associado a um protocolo de hibridização da dentina radicular com Scotchbond Multi Purpose (SBMP) após o uso de diferentes substâncias químicas auxiliares endodônticas (Hipoclorito de Sódio 5,25%, Gluconato de Clorexidina 2%, EDTA 17% e ácido fosfórico 37%). Para avaliar o selamento, foram utilizadas raízes palatinas de molares superiores divididas em 18 grupos (n=10) que foram tratadas com diferentes substâncias químicas, obturadas com cimento endodôntico AH Plus associado a cones resinosos ou a cones de guta-percha. Em alguns grupos obturados com AH Plus + cones resinosos, a dentina foi hibridizada antes da aplicação do material obturador. O selamento coronário foi avaliado pelo método de filtração de fluidos. Um espécime de cada grupo foi levado ao MEV para avaliação morfológica da interface de união entre os materiais obturadores e a dentina radicular. Para a avaliação da resistência de união do cimento à dentina radicular foram utilizadas 60 raízes de dentes bovinos, cortadas longitudinalmente, que receberam tratamento com as substâncias químicas auxiliares utilizadas na avaliação do selamento (n=5). Foram criadas seis perfurações nas raízes selecionadas, duas por terço, onde foi inserido o cimento AH Plus, após o tratamento da dentina com o sistema adesivo SBMP. Após a presa do cimento, os corpos-de-prova foram submetidos ao teste de resistência ao cisalhamento por extrusão ?Push out?. Posteriormente, o modo de fratura foi analisado em lupa estereoscópica 32X. Um espécime de cada grupo foi avaliado no MEV para confirmação das análises feitas pela lupa. A análise do modo de fratura demonstrou (22,77%) fraturas adesivas, (11,67%) fraturas coesivas em cimento e (65,55%) fraturas mistas para o protocolo SBMP/ AH Plus, enquanto que para o AH Plus a distribuição foi (86,11%) coesivas em cimento e (13,89%) mistas. A análise estatística (Dixon-Grubbs-Neuman, Kolmogorov-Smirnov, Cochran e Tukey HSD) demonstrou que o selamento coronário, após a hibridização dentinária com o SBMP e obturação com cone Resinoso + AH Plus, foi superior ao promovido pela guta-percha associada ao AH Plus, para todos os protocolos de irrigação (p ? 0,05). Para a resistência de união, a aplicação do SBMP se mostrou desfavorável, pois diminuiu a resistência de união do AH Plus (p ? 0,05). As substâncias químicas agiram diferentemente sobre a resistência de união nos grupos onde foi aplicado o adesivo, sendo observado que o tratamento dentinário com clorexidina e soro apresentou melhores valores de resistência quando foram associados ao condicionamento dentinário com EDTA 17%, diferentemente do que ocorreu nos grupos onde se aplicou hipoclorito de sódio 5,25% que apresentou melhores resultados com a utilização do ácido fosfórico 37%. Houve correlação inversa entre resistência de união e capacidade de selamento. Pode-se concluir que o uso do sistema adesivo Scotchbond Multi Purpose melhorou a capacidade de selamento coronário do AH Plus para todos os protocolos de irrigação utilizados, e que a resistência de união deste cimento foi diminuída quando o adesivo foi aplicado, sendo influenciada pelo tipo de condicionamento e substâncias químicas
Abstract: The aim of this in vitro study was to evaluate the sealing ability and bond strength of AH Plus sealer associated with a hybridization protocol of root dentin with ScotchbondMulti Purpose (SBMP) after the use to different endodontic auxiliary chemical substances (5.25% sodium hypochlorite and 2% Chlorhexidine and 17 EDTA) in One hundred-eighty palatal roots of maxillary molars were selected and divided into 18 groups according to the dentin protocol treatment (n=10), filled with AH Plus sealer associated with resinous cones or gutta-percha in order to evaluate the sealing ability by fluid filtration (FLODEC system). In s groups that were used in the AH Plus + resinous cones, was hybridized dentin before applying the sealing material. One specime from each group was taken to a SEM morphology analysis of the bonded interfaces between sealers and dentin. For the bond strength test, 60 root bovine teeth were selected and treated with each auxiliary chemical substances selected (n=5). Six holes were poked in each root, being two in the cervical, middle and apical third of the root. The roles were filled with AH Plus sealer with or without the adhesive system, and subsequently, submitted to push out test. Thereafter, the fracture mode was examined using stereomicroscope (x32). One specimen from each was SEM analyzed. The fracture mode methodology revealed a 22.77% of adhesive, 11.67% of cohesive and 65.55% of mixture fracture for the SBMP / AH Plus protocol. In contrast, the AH Plus protocol indicated 86.11% of cohesive and 13.89% of mixed fracture. Statistical analysis (Dixon-Grubs-Neuman, Kolmogorov-Smirnov, Cochran and Tukey HSD) showed that the ScotchBond Multi Purpose (SBMP) + Resilon cone + AH Plus sealer group promoted a higher sealing ability than the gutta-percha + AH Plus sealer group (p < 0.05), regardless the auxiliary chemical substance. The bond strength were lower with the SBMP application than without its use (p<0.05). The chemicals acted differently on the bond strength in groups where the adhesive was applied, we observed that the dentin treatment with chlorhexidine and serum values showed better resistance when they were associated with dentin conditioning with 17% EDTA, unlike what occurred in the groups where sodium hypochlorite is applied, that it was found better results with the use of phosphoric acid 37%. A reverse correlation was found between bond strength and sealing ability. Was concluded that the use of adhesive system Scotchbond Multi Purpose improved coronal sealing ability of AH Plus for all protocols used irrigation, and that the bond strength of cement was reduced when the adhesive was applied, being influenced by type conditioning and chemicals substances.
Mestrado
Endodontia
Mestre em Clínica Odontológica
Prado, Maíra do 1983. "Avaliação da interação entre as diferentes substâncias químicas auxiliares utilizadas em endodontia e seus efeitos nas etapas do tratamento endodôntico". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290437.
Texto completoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Introdução: O objetivo do presente trabalho foi avaliar a interação entre as diferentes substâncias químicas auxiliares, utilizadas em endodontia, e seus efeitos nas etapas do tratamento endodôntico. Métodos: Soluções de hipoclorito de sódio (NaOCl) a 0,16%, 1%, 2,5% e 5,25%, clorexidina 2% solução e gel, EDTA 17%, ácido cítrico 10% e ácido fosfórico 37% foram utilizadas isoladamente ou associadas entre si na proporção 1:1. As mesmas foram analisadas quimicamente por espectrometria de massa; e microbiologicamente pelo método de difusão em ágar, contra diferentes patógenos. Adicionalmente, foram avaliados onze protocolos de irrigação em relação à formação de smear layer química por microscopia eletrônica de varredura. Por fim, foram avaliados 9 protocolos de irrigação associados a dois diferentes sistemas de obturação, guta-percha/ AH Plus e Resilon/ Real Seal SE, em relação à microinfiltração coronária e à resistência de união da dentina aos materiais obturadores. Resultados: O NaOCl, em todas as concentrações, associado à clorexidina em ambas as formulações, levou à formação de precipitado, assim como a associação entre a clorexidina e o EDTA e entre clorexidina e solução salina. Todas as associações avaliadas apresentaram algum grau de inibição contra os patógenos testados. Irrigação intermediária, com 10 mL de água destilada, entre as soluções de NaOCl e clorexidina, não foram capazes de inibir a formação de smear layer química, assim como irrigações com EDTA e ácido cítrico. Dos diferentes protocolos de irrigação avaliados, aqueles que apresentaram uma irrigação final com solução de clorexidina 2% tiveram níveis reduzidos de microinfiltração coronária. Em relação à resistência de união à dentina, no sistema obturador guta-percha/AH Plus, os grupos em que se utilizou as associações NaOCl/ácido fosfórico e clorexidina/EDTA apresentaram maiores valores de resistência de união, ao passo que no sistema Resilon/Real Seal SE, os maiores valores foram encontrados nos grupos clorexidina/ácido fosfórico. A utilização da clorexidina como irrigante final não afetou negativamente os sistemas obturadores avaliados. Conclusões: A interação entre as substâncias químicas auxiliares pode levar à formação de precipitados. As diferentes substâncias químicas auxiliares, quando associadas, possuem atividade antimicrobiana. Irrigações intermediárias entre as diferentes substâncias químicas auxiliares são necessárias para reduzir ou até mesmo impedir a formação de precipitados, visualizados na superfície dentinária como uma smear layer química. Durante o preparo químicomecânico, as diferentes substâncias químicas auxiliares geram modificações na superfície dentinária que influenciam na microinfiltração coronária e na resistência de união dos sistemas obturadores guta-percha/AH Plus e Resilon/Real Seal SE
Abstract: Introduction: The aim of the present study was to evaluate the interaction among different chemical auxiliary substances used in endodontics and their effects on different steps of endodontic treatment. Methods: 0.16%, 1%, 2.5% and 5.25% sodium hypochlorite solutions (NaOCl), 2% chlorhexidine solution and gel, 17% EDTA, 10% citric acid, 37% phosphoric acid, distilled water, and saline solution were used both associated with each other (1:1 ratio) and not associated. The solutions were chemically examined with mass spectrometry. They were microbiologically examined using the Agar Diffusion Method, against different pathogens. In addition, eleven protocols were analyzed in regards to chemical smear layer with scanning electron microscopy. Finally, nine irrigation protocols (associated with two filling systems, i.e. gutta-percha/AH Plus and Resilon / Real Seal SE) were examinated regarding coronal microleakage and were examined as well regarding their bond strength with dentin. Results: NaOCl, at all concentrations, associated with both chlorhexidine formulations, led to precipitate formation, similar to the association between chlorhexidine/EDTA, and the chlorhexidine/saline solution association. All associations had some degree of inhibition against the evaluated pathogens. Intermediate flush, with 10 mL of distilled water, between NaOCl and chlorhexidine did not inhibit chemical smear layer formation, similar to intermediate flushes with EDTA and citric acid. Among the different irrigation protocols that were evaluated, when final flush with 2% chlorhexidine was present, the lowest levels of coronal microleakage were found. Regarding the bond strength to dentin, in the gutta-percha/AH Plus system, the groups with NaOCl/phosphoric acid and chlorhexidine/EDTA associations showed higher bond strength values. In the Resilon/Real Seal SE system, the highest values were found in the chlorhexidine/phosphoric acid groups. The use of chlorhexidine as a final flush did not negatively affect the filling systems evaluated. Conclusions: The interaction among the auxiliary chemical substances may lead to precipitate formation. The association between the different substances has antimicrobial activity. Intermediate flushes are necessary to reduce or even avoid the formation of chemical smear layer on the dentin surface. During the chemo-mechanical preparation, the various auxiliary chemical substances used do modify the dentine surface. These modifications have influence in the coronal microleakage and in the bond strength of the filling systems gutta-percha/AH Plus and Resilon / Real Seal SE
Doutorado
Endodontia
Doutora em Clínica Odontológica
Ribeiro, Ana Graça Casais e. Silva. "Avaliação da remoção da camada residual do terço apical dos canais radiculares utilizando diferentes substâncias químicas auxiliares da instrumentação: estudo in vitro". Programa de Pós- Graduação em Odontologia da UFBA, 2004. http://www.repositorio.ufba.br/ri/handle/ri/10512.
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A ação dos instrumentos endodônticos sobre as paredes do canal radicular tem proporcionado a formação de resíduos, também chamados de camada residual, lama dentinária, barro dentinário ou smear layer, que, quando não removidos, poderão interferir no selamento apical, quando da etapa da obturação. O objetivo deste estudo é avaliar in vitro a capacidade das substâncias químicas auxiliares da instrumentação (Hipoclorito de Sódio(NaOCl), EDTA, Endo-PTC) de remover a camada residual do terço apical dos canais radiculares. Foram utilizados 60 dentes unirradiculares humanos, extraídos, divididos aleatoriamente em 6 grupos de 10 dentes, onde seus canais foram preparados com diferentes substâncias, assim distribuídos: Grupo I ? Endo-PTC/NaOCl a 1%; Grupo II - NaOCl a 1%; Grupo III ? Endo-PTC/NaOCl a 1%, lavagem com EDTA e mais NaOCl a 1%; Grupo IV - NaOCl a 1% , lavagem com EDTA e mais irrigação final com NaOCl a 1%; Grupo V - EDTA mais lavagem final com NaOCl a 1%; Grupo VI ? EDTA e NaOCl a 1% usados alternadamente. Para serem analisadas, as raízes foram seccionadas no sentido mésio-distal e foi escolhida a secção de contorno do canal mais nítido. Os espécimes foram então analisados pela microscopia eletrônica de varredura (MEV). Os resultados demonstraram que os grupos onde foi utilizado o EDTA, independentemente da seqüência de uso, apresentaram os melhores resultados, sem diferença estatisticamente significante entre si, e que nos grupos que não utilizaram este fármaco ficou comprometida de forma significante a qualidade da remoção da camada residual.
Salvador
Maekawa, Lilian Eiko [UNESP]. "Avaliação in vitro da ação de substâncias químicas auxiliares e medicações intracanais sobre Escherichia coli e sua endotoxina em canais radiculares". Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/90430.
Texto completoFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A proposta deste trabalho foi avaliar a efetividade de substâncias químicas auxiliares e medicações intracanais sobre Escherichia coli e sua endotoxina em canais radiculares. Foram utilizados 120 dentes unirradiculados que após secção das coroas as raízes foram impermeabilizadas e esterilizadas. Os canais foram contaminados com suspensão de Escherichia coli por 14 dias. Após a coleta de confirmação, foram instrumentados até a lima K 50 e escalonados até a K 80. Doze raízes foram utilizadas como controle (G4) e 108 raízes foram divididas em 3 grupos (n=36), de acordo com a substância química auxiliar utilizada: G1) hipoclorito de sódio 2,5%; G2) clorexidina gel 2% (CLX); G3) solução fisiológica apirogênica. Após o preparo biomecânico (PBM) estes grupos foram subdividos de acordo com a medicação intracanal utilizada (MIC) (n=12): A) hidróxido de cálcio (Ca(OH)2), B) polimixina B e C) Ca(OH)2 + CLX. No grupo G4 foi utilizada solução fisiológica apirogênica sem MIC. Foram realizadas coletas do conteúdo do canal radicular imediatamente após o PBM (1ª coleta), após 7 dias do PBM (2ª coleta), imediatamente após 14 dias da ação da MIC (3ª coleta) e 7 dias após remoção da MIC (4ª coleta). Para todas as coletas foram avaliadas: a) atividade antimicrobiana; b) quantificação de endotoxina pelo teste cromogênico do lisado de amebócitos de Limulus. As substâncias químicas auxiliares e as MICs utilizadas foram capazes de eliminar completamente E. coli dos canais radiculares. Para os resultados da quantidade de endotoxina foi aplicado teste estatístico Kruskall-Wallis e Dunn (5%). Na primeira e na segunda coleta verificou-se que os grupos G1 e G2 foram diferentes estatisticamente do grupo G3 (p<0,05). Na terceira coleta, o grupo G2B foi semelhante aos grupos G1A, G1B e G3A e o grupo G3B foi semelhante aos demais (p>0,05).
The purpose of this study was to evaluate the effectiveness of auxiliary chemical substances and intracanal medications on Escherichia coli (E. coli) and its endotoxin in root canals. The study was conducted on 120 single-rooted teeth. After sectioning of crowns, the root canals were contaminated with a suspension of E. coli for 14 days. After collection of confirmation, they were submitted to instrumentation up to K 50 file and step-back preparation up to K 80 file. Thereafter, twelve roots were used as control group (G4) and 108 roots were divided into 3 groups (n=36) according to the auxiliary chemical substance used: G1) 2.5% sodium hypochlorite; G2) 2% chlorhexidine gel (CLX); G3) apyrogenic saline solution. After biomechanical preparation (BMP), these groups were subdivided according to the intracanal medication (ICM) employed (n=12): A) calcium hydroxide (Ca(OH)2), B) polymyxin B, and C) Ca(OH)2 + 2% CLX gel. The control group (G4) was used apyrogenic saline solution without application of intracanal medication. Samples of the root canal content were collected immediately after PBM (1st collection), at 7 days after PBM (2nd collection), immediately after 14 days of ICM activity (3rd collection), and 7 days after removal of ICM (4th collection). The following aspects were evaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the Limulus amebocyte lysate test. The auxiliary chemical substances and ICMs employed were able to completely eliminate E. coli from root canals. Results of the amount of endotoxin were analyzed by the Kruskal-Wallis and Dunn (5%) statistical tests. In the first and second collection, it was verified that groups G1 and G2 were statistically different from group G3 (p<0.05). In the third collection, groups G1C, G2A, G2C and G3C showed the lowest endotoxin values and were statistically similar to groups G1A, G1B, G3A and G3B (p>0.05).
Maekawa, Lilian Eiko. "Avaliação in vitro da ação de substâncias químicas auxiliares e medicações intracanais sobre Escherichia coli e sua endotoxina em canais radiculares /". São José dos Campos : [s.n.], 2007. http://hdl.handle.net/11449/90430.
Texto completoBanca: Maria Renata Giazzi Nassri
Banca: Claudio Antonio Talge Carvalho
Resumo: A proposta deste trabalho foi avaliar a efetividade de substâncias químicas auxiliares e medicações intracanais sobre Escherichia coli e sua endotoxina em canais radiculares. Foram utilizados 120 dentes unirradiculados que após secção das coroas as raízes foram impermeabilizadas e esterilizadas. Os canais foram contaminados com suspensão de Escherichia coli por 14 dias. Após a coleta de confirmação, foram instrumentados até a lima K 50 e escalonados até a K 80. Doze raízes foram utilizadas como controle (G4) e 108 raízes foram divididas em 3 grupos (n=36), de acordo com a substância química auxiliar utilizada: G1) hipoclorito de sódio 2,5%; G2) clorexidina gel 2% (CLX); G3) solução fisiológica apirogênica. Após o preparo biomecânico (PBM) estes grupos foram subdividos de acordo com a medicação intracanal utilizada (MIC) (n=12): A) hidróxido de cálcio (Ca(OH)2), B) polimixina B e C) Ca(OH)2 + CLX. No grupo G4 foi utilizada solução fisiológica apirogênica sem MIC. Foram realizadas coletas do conteúdo do canal radicular imediatamente após o PBM (1ª coleta), após 7 dias do PBM (2ª coleta), imediatamente após 14 dias da ação da MIC (3ª coleta) e 7 dias após remoção da MIC (4ª coleta). Para todas as coletas foram avaliadas: a) atividade antimicrobiana; b) quantificação de endotoxina pelo teste cromogênico do lisado de amebócitos de Limulus. As substâncias químicas auxiliares e as MICs utilizadas foram capazes de eliminar completamente E. coli dos canais radiculares. Para os resultados da quantidade de endotoxina foi aplicado teste estatístico Kruskall-Wallis e Dunn (5%). Na primeira e na segunda coleta verificou-se que os grupos G1 e G2 foram diferentes estatisticamente do grupo G3 (p<0,05). Na terceira coleta, o grupo G2B foi semelhante aos grupos G1A, G1B e G3A e o grupo G3B foi semelhante aos demais (p>0,05).
Abstract: The purpose of this study was to evaluate the effectiveness of auxiliary chemical substances and intracanal medications on Escherichia coli (E. coli) and its endotoxin in root canals. The study was conducted on 120 single-rooted teeth. After sectioning of crowns, the root canals were contaminated with a suspension of E. coli for 14 days. After collection of confirmation, they were submitted to instrumentation up to K 50 file and step-back preparation up to K 80 file. Thereafter, twelve roots were used as control group (G4) and 108 roots were divided into 3 groups (n=36) according to the auxiliary chemical substance used: G1) 2.5% sodium hypochlorite; G2) 2% chlorhexidine gel (CLX); G3) apyrogenic saline solution. After biomechanical preparation (BMP), these groups were subdivided according to the intracanal medication (ICM) employed (n=12): A) calcium hydroxide (Ca(OH)2), B) polymyxin B, and C) Ca(OH)2 + 2% CLX gel. The control group (G4) was used apyrogenic saline solution without application of intracanal medication. Samples of the root canal content were collected immediately after PBM (1st collection), at 7 days after PBM (2nd collection), immediately after 14 days of ICM activity (3rd collection), and 7 days after removal of ICM (4th collection). The following aspects were evaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the Limulus amebocyte lysate test. The auxiliary chemical substances and ICMs employed were able to completely eliminate E. coli from root canals. Results of the amount of endotoxin were analyzed by the Kruskal-Wallis and Dunn (5%) statistical tests. In the first and second collection, it was verified that groups G1 and G2 were statistically different from group G3 (p<0.05). In the third collection, groups G1C, G2A, G2C and G3C showed the lowest endotoxin values and were statistically similar to groups G1A, G1B, G3A and G3B (p>0.05).
Mestre
Monteiro, Patricia Guerreiro. "Análise da limpeza dentinária em canais radiculares preparados com um sistema rotatório e diferentes substâncias químicas". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/23/23145/tde-11042008-110242/.
Texto completoThe development of nickel-titanium (NiTi) endodontic instruments results in more quickness during the root canal shaping phase that induce us to discuss if really would be the chemical substances are having opportunities to act properly, considering that the time of action of the same was significantly reduced. The object of this research was evaluate, using the scanning electron microscopy (SEM) and computerized analysis, the cleaning on root canal walls in coronal, middle and apical thirds in mandibular human incisives prepared with K3 NiTi rotary instruments and different chemical substances: 2,5% sodium hypochlorite (pH 11,0), Endo PTC cream at normal consistency (Endo PTC-N) neutralized by 0,5% sodium hypochlorite (pH 11,0), Endo PTC cream with lower density (Endo PTC-L) neutralized by 0,5% sodium hypochlorite (pH 11,0) and chlorhexidine gel (Endogel). Concluded the cleaning and shaping phase, all the groups received a final irrigation with of 0,5% sodium hypochlorite solution (pH 11,0) followed by 17% EDTA-T solution, except the Endogel group that received two different regimens of final irrigation, one group with 20 ml of physiological serum and another with the 17% EDTA-T solution. The samples were prepared for the SEM analysis and the images obtained were analyzed using the Scion Image program. The results showed a significant difference between the groups tested seeing that the Endo PTC-L group, in middle and apical thirds and Endogel followed by the final irrigation with EDTA-T group, in middle third were superiors in comparation with the other groups.
Jauvart, Damien. "Sécurisation des algorithmes de couplages contre les attaques physiques". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV059/document.
Texto completoThis thesis focuses on the resistance of Pairing implementations againstside channel attacks. Pairings have been studied as a cryptographic tool for the pastfifteen years and have been of a growing interest lately. On one hand, Pairings allowthe implementation of innovative protocols such as identity based encryption, attributebased encryption or one round tripartite exchange to address the evolving needs ofinformation systems. On the other hand, the implementation of the pairings algorithmshave become more efficient, allowing their integration into embedded systems.Like for most cryptographic algorithms, side channel attack schemes have beenproposed against Pairing implementations. However most of the schemes describedin the literature so far have had very little validation in practice. In this thesis, westudy the practical feasibility of such attacks by proposing a technique for optimizingcorrelation power analysis on long precision numbers. We hence improve by a factorof 10 the number of side-channel leakage traces needed to recover a 256-bit secret keycompared to what is, to our best knowledge, one of the rare practical implementationsof side channel attacks published. We also propose a horizontal attack, which allow usto attack the twisted Ate pairing using a single trace.In the same way, countermeasures have been proposed to thwart side channel attacks,without any theoretical or practical validation of the efficiency of such countermeasures.We here focus on one of those countermeasures based on coordinatesrandomization and show how a collision attack can be implemented against this countermeasure.As a result, we describe how this countermeasure would have to be implementedto efficiently protect Pairing implementations against side channel attacks.The latter studies raise serious questions about the validation of countermeasures whenintegrated into complex cryptographic schemes like Pairings
Pontie, Simon. "Sécurisation matérielle pour la cryptographie à base de courbes elliptiques". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT103/document.
Texto completoMany applications require achieving high security level (confidentiality or integrity). My thesis is about hardware acceleration of asymmetric cryptography based on elliptic curves (ECC). These systems are rarely in a controlled environment. With this in mind, I consider potential attackers with physical access to the cryptographic device.In this context, a very flexible crypto-processor was developed that can be implemented as an ASIC or on FPGAs. To choose protections against physical attacks (power consumption analysis, fault injection, etc), I evaluate the security against side-channel attacks and the cost of the counter-measure based on operation unification. By mounting a new attack against a chip using Jacobi quartic curves, I show that re-using operands is detectable. By exploiting only some power consumption traces, I manage to recover the secret. I present also a new counter-measure allowing finding a compromise between security level, performances, and overheads. It uses random windows to accelerate computation, mixed to an optimized usage of dummy operations
Demange, Loïc. "Mise en œuvre de BIKE, vulnérabilités et contre-mesures". Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS035.
Texto completoBIKE is a post-quantum key encapsulation scheme (KEM) selected for the fourth round of the NIST standardization campaign. Its security is based on the robustness of the syndrome decoding problem for quasi-cyclic codes, and provides competitive performance with the other candidates in the 4th round, making it relevant for use in real-life cases. The scientific community has strongly encouraged analysis of its resistance to auxiliary channel attacks, and several works have already highlighted various weaknesses. To correct them, the latter have proposed ad hoc countermeasures. However, in contrast to the well-documented line of research on masking latice-based algorithms, the possibility of generically protecting code-based algorithms through masking has only been marginally investigated in a 2016 paper by Cong Chen et al. At this stage of the standardization campaign, it is important to evaluate the possibility of fully masking the BIKE scheme and the resulting cost in terms of performance. The aim of this thesis is therefore to propose a BIKE algorithm whose security has been proven, by carrying out the entire process in a masked way, without ever directly manipulating sensitive data. To achieve this, we use "gadgets", which are masked functions identified by levels of non-interference: NI (non-interference) and SNI (strong non-interference). In simple terms, SNI allows gadgets to be composable: they can be called one after the other, with the same variables. NI, on the other hand, requires greater care in terms of the variables manipulated. Gadgets are the subject of proofs, based on the ISW model, giving a real argument of safety and robustness to the algorithmic. If the scheme is proven to be end-to-end safe, it is a priori robust.It should be noted that masking was initially developed for symmetrical schemes and was based on Boolean masking. It's only recently that we've begun to take an interest in asymmetrical schemes, and in particular lattice-based schemes. For this purpose, arithmetic masking has been the main one used, although Boolean conversions could be performed to achieve certain things (value comparison among others).Today, we're able to offer a masked implementation of BIKE, based on a proven safe algorithm. As BIKE manipulates binary data, we focused on Boolean masking. We therefore had to :- reuse existing gadgets,- adapt and optimize existing arithmetic masking gadgets,- create new gadgets. Each time, we had to carry out proofs, and also prove their composition within each BIKE function, to arrive at the full scheme proof.As a reminder, BIKE is based on QC-MDPCs, and its arithmetic is based on dense, sparse polynomials, so choices had to be made regarding representation and the way calculations are performed. We therefore decided to explore two paths (fully dense and hybrid sparse-dense) and see what was most relevant between the two. In addition to the full C implementation, benchmarks were carried out, enabling us to see where performance was limited and where the bottlenecks were.In the end, we propose a fully masked and proven-safe BIKE algorithm, with its C implementation and various benchmarks to judge its performance
Bourdin, Céline. "Etude des sous-unités auxiliaires du canal sodium dépendant du potentiel d'insecte : Approches moléculaires, électrophysiologiques et pharmacologiques". Phd thesis, Université d'Angers, 2013. http://tel.archives-ouvertes.fr/tel-00950043.
Texto completoSantos, Ivana Lins. "Avaliação da capacidade de remoção da smear layer das paredes de canais instrumentados utilizando diferentes substancias quimicas auxiliares ao preparo quimico-mecanico : estudo in vitro". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290480.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-04T21:47:13Z (GMT). No. of bitstreams: 1 Santos_IvanaLins_M.pdf: 4446919 bytes, checksum: 906c2bb88c7bbc1591d2d43d0c214552 (MD5) Previous issue date: 2005
Resumo: O presente trabalho avaliou, in vitra, a capacidade de remoção da smear layer das paredes dos canais radiculares após o preparo químico-mecânico realizado com diferentes substâncias químicas auxiliares. Selecionou-se 54 dentes humanos unirradiculares, com canais retos e ápices formados, divididos em grupos seguindo o protocolo de irrigação: G1: NaOCI 5,25% + EDTA 17%; G2: solução fisiológica 0,9%; G3: clorexidina (CLX) gel 2% pH neutro + solução fisiológica 0,9%; G4: CLX gel 2% pH neutro + solução fisiológica 0,9% + EDTA 17%; G5: CLX gel a 2% pH ácido + solução fisiológica 0,9% e G6: CLX gel a 2% pH ácido + solução fisiológica 0,9% + EDTA 17%. Os grupos foram instrumentados utilizando técnica manual híbrida, sendo analisadas quatro áreas distintas em cada terço do canal radicular: apical, médio e cervical, através do microscópio eletrônico de varredura (MEV) atribuindo escores de 0 a 3 de acordo com Gaberogllio & Becce (1994), considerando a capacidade de limpeza de cada substância. A análise estatística utilizou o software SPSS (Statistical Package for Social Sciences) e o teste não paramétrico de Mann-Whitney. Concluímos que a combinação das soluções de NaOCI a 5,25% e irrigação final com EDTA a 17% foi mais efetiva na remoção da smear layer das paredes dos canais radiculares quando comparado com as demais soluções testadas (p<0,05). O uso do gluconato de clorexidina gel a 2% com pH ácido + EDTA a 17% foi mais efetivo apenas quando comparado com a solução fisiológica e o gel de gluconato de clorexidina a 2% com pH neutro + solução fisiológica (p<0,05). A clorexidina gel neutra + solução fisiológica foi a que apresentou pior condição de limpeza das paredes dos canais radiculares. O terço apical apresentou condições de limpeza estatisticamente inferiores, independente das soluções testadas
Abstract: This in vitro study evaluted the effects of 2% chlorhexidine gel with acid pH on smear layer removal after chemomechanical debridement as endodontic irrigating solution. Fifty-four single-root extracted of human teeth were separated into six groups: G1: 5.25% NaOCI + 17% EDTA; G2: saline solution; G3: 2% chlorhexidine gel (CHX) neutral pH + saline solution; G4: 2% CHX gel neutral pH + saline solution + EDTA 17%; G5: 2% CHX gel acid pH + saline solution and G6: 2% CHX gel acid pH + Saline solution + EDTA 17%. After instrumentation using the respective irrigants, the root canais were examined by scanning electron microscopy in four differents areas in each third of the canal: apical, middle and carona!. The areas photographed were evaluated according to the rating system developed by Gaberoglio & Becce (1994). The data were analyzed using the Mann-Whitney test to determine whether there was any significant difference in the ability of the irrigating regimens to remove the smear layer. In the coronal and middle thirds, 5.25% NaOCI + 17% EDTA effectively removes the smear layer when compared with the others substances (p<0.05).In the coronal third, the 2% CHX gel acid pH + EDTA 17% were statistically more effective in removing the smear layer than with saline solution; 2% CHX gel neutral; 2% CHX gel acid pH (p<0.05). In the midlle third, this irrigant had the same result, except when compared with the 2% CHX gel acid pH alone. In the apical third, the difference was significant and better to the group flushed with 5.25% NaOCI + 17% EDTA compared with saline solution and 2% CHX gel neutral pH + saline solution
Mestrado
Endodontia
Mestre em Clínica Odontológica
Carvalho, Alessandra Sverberi [UNESP]. "Análise, por MEV, da efetividade de soluções irrigadoras e substâncias químicas auxiliares na limpeza de canais radiculares e estudo complementar da interferência desta limpeza na penetração do cimento obturador nos túbulos dentinários". Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/90428.
Texto completoCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A proposta deste estudo foi avaliar, através de MEV, a capacidade de limpeza de diferentes combinações de soluções irrigadoras e substâncias químicas auxiliares ao preparo biomecânico e a penetração de dois cimentos no interior dos túbulos dentinários. Foram utilizados 48 dentes unirradiculados humanos que tiveram seus canais instrumentados de forma padronizada, variando a solução irrigadora utilizada (n=12): G1- Preparo Biomecânico (PBM) com NaOCl 2,5% þ+ EDTA 17%; G2- PBM com gel de Clorexidina 2% + EDTA 17%; G3- PBM com Canal Mais (Septodont) + NaOCl 2,5%; G4- PBM com soro fisiológico + EDTA 17% (controle). Terminadas as instrumentações, 8 dentes de cada grupo foram clivados e preparados para leitura em MEV, com aumento de 2000X, avaliando a limpeza dos terços cervical, médio e apical. A área analisada foi quantificada pelo total de túbulos dentinários presentes, pela porcentagem de túbulos abertos da região avaliada. Os dados relativos à porcentagem de túbulos abertos foram submetidos aos testes estatísticos ANOVA e Tukey (p=0,05). Os resultados mostraram diferenças estatisticamente significantes, com maior quantidade de túbulos abertos nos grupos G1 e G3 e menor quantidade nos grupos G2 e G4. Em ordem decrescente a capacidade de limpeza das soluções foi a seguinte: Canal Mais > NaOCl 2,5% > Clorexidina gel 2% > solução salina fisiológica. Foi possível observar grande erosão dentinária peritubular e intertubular nos dentes instrumentados com o Canal Mais. Em todos os grupos a limpeza obtida no terço cervical foi superior à alcançada nos terços médio e apical, com diferença estatisticamente significante apenas no grupo da clorexidina. Com caráter ilustrativo e qualitativo, as quatro raízes remanescentes em cada grupo foram subdivididas em dois grupos de duas raízes cada e obturadas, pela técnica da condensação lateral, com cones de...
The process of cleaning and disinfecte of the rootcanal system is an essential step for the success of endodontic treatment. Chemicals employed as irrigants during endodontic treatment must have good ability to lubricate the root canal walls and clean the dentinal tubules, in order to allow better diffusion of root canal dressing and good adaptation of sealers to the dentinal walls. This study aimed to investigate, by SEM analysis, the cleaning ability of different combinations of irrigants and auxiliary chemicals and the penetration of Acroseal and Epiphany sealers into the dentinal tubules. The study was conducted on 48 single-rooted human teeth submitted to standardized instrumentation, using different irrigants, as follows (n=12): G1- Biomechanical preparation (BMP) with 2.5% NaOCl + 17% EDTA; G2- BMP with 2% chlorhexidine gel + 17% EDTA; G3- BMP with Canal Mais (Septodont do Brasil) + 2.5% NaOCl; G4- BMP with saline + 17% EDTA (control). Eight teeth from each group were longitudinally sectioned and prepared for SEM analysis, with 2000x magnification, for evaluation of cleaning at the cervical, medium and apical thirds. The analyzed area was quantified according to the percentage of open tubules at each region. The values were submitted to statistical analysis by the ANOVA and Tukey tests, at a significance level of 5%. The results revealed statistical differences, namely G1 and G3 were statistically different from G2 and G4. There was significant dentinal erosion in teeth instrumented with Canal Mais. In all groups, the cleaning achieved at the cervical third was better compared to the medium and apical thirds, with statistically significant difference only for the chlorhexidine group. For the purposes of illustration, the four remaining roots in each group were subdivided into two groups with two roots each and filled by the lateral condensation technique with gutta-percha points... (Complete abstract click electronic access below)
Oliveira, Sarah Almeida Coelho de [UNESP]. "Eficácia do preparo biomecânico utilizando hipoclorito de sódio 1%, clorexidina gel 2% e extrato glicólico de própolis 12%, como substâncias químicas auxiliares sobre o ácido lipoteicóico de Enterococcus faecalis". Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/90390.
Texto completoBactérias Gram-positivas presentes nas infecções dos canais radiculares possuem em sua parede celular ácido lipoteicóico (LTA), que apresenta potente ação citotóxica. O objetivo deste estudo foi avaliar a capacidade de substâncias químicas auxiliares como hipoclorito de sódio 1%, clorexidina gel 2%, extrato glicólico de própolis 12%, em neutralizar o ácido lipoteicóico de Enterococcus faecalis em canais radiculares, analisando os efeitos na produção de citocinas (IL-1β, IL-6, TNF-α) por macrófagos (RAW 264.7). Solução salina fisiológica apirogênica 0,9% foi utilizada como controle positivo. Foram utilizadas 40 raízes de dentes unirradiculares padronizadas, distribuídos em 4 grupos (n=10) em placas de poliestireno. Após esterilização, foram inoculados 10μL de uma solução de LTA de Enterococcus faecalis nos canais radiculares por 24h, processo repetido 3 vezes, e posteriormente, realizou-se a instrumentação dos canais radiculares. Foi realizada a coleta do conteúdo imediatamente após a instrumentação. Estas amostras foram utilizadas para verificar se as substâncias químicas apresentavam capacidade de neutralizar o LTA. Para tanto, macrófagos (RAW 264.7) foram ativados com as amostras coletadas dos canais radiculares e os sobrenadantes foram utilizados para verificar a produção de citocinas (IL-1β, IL-6, TNF-α) pelo teste imunoenzimático (ELISA). Os resultados foram analisados estatisticamente (Kruskal-Wallis, e teste de Dunn 5%). Em relação a produção de IL-1β e IL-6, os níveis encontrados nos grupos instrumentados com NaOCl e PRO foram inferiores aos grupos CLX e SS. Em TNF-α todos os grupos experimentais, NaOCl: 1496pg/mL, PRO: 1113pg/mL, CLX: 961pg/mL e SS: 1046pg/mL foram estatisticamente semelhantes entre si (p>0,05). Conclui-se que as substâncias químicas auxiliares testadas: NaOCl e PRO...
The purpose of this study is to assess the ability of 1%sodium hypochlorite, 2%chlorhexidine gel, 12 % glycolic extract of propolis and 0,9%apyrogenic saline physiological solution in the neutralization of the lipoteichoic acid (LTA) derived from Enterococcus faecalis in root canals by analyzing the production of IL-1β,IL-6,TNF-α by macrophages (RAW264.7). For this study, 40 single-rooted roots, standardized to 16mm, were used. The root canals were prepared using a 15K-file and then prepared using rotatory system (BioRaCe) until the working length (15mm); the specimens were distributed in microplates with 10 specimens each. After sterilization, 10μL of E. faecalis LTA solution was used in the root canals, and subsequently was perfomed a root canal instrumentation with rotatory system. The samples were then divided into 4 groups (n=10) on the basis of the irrigating agent used as follows: (a) NaOCl: 1%sodium hypochlorite; (b) CLX: 2%chlorhexidine gel; (c) PRO: 12% glycolic extract of propolis; (d) group SS: 0,9%apyrogenic saline physiological solution. The root canal content was collected immediately after instrumentation to verify the production of IL-1β, IL-6, TNF-α, from the macrophages, tested by ELISA. Results were analyzed statistically by (Kruskal-Wallis test, pvalue = 0.0001 <0.05 and Dunn test 5%). Where it was found that in levels found in the groups instrumented with NaOCl and PRO were lower than CLX and SS. TNF-α in all experimental groups, NaOCl: 1496pg/mL, PRO: 1113pg/mL, CLX: 961pg/mL and SS: 1046pg/mL were statistically similar (p> 0.05). It is concluded that the auxiliary chemicals tested: NaOCl and PRO were effective in neutralizing the lipoteichoic acid (LTA) of E. faecalis in root canals compared with the SS group (positive control). For group CLX cytokine production (IL-1β) and... (Complete abstract click electronic access below)
Mercier-François, Aurélie. "Adressage et expression fonctionnelle des canaux sodiques cardiaques Nav1.5 : rôle majeur de la sous-unité régulatrice β1". Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2272/document.
Texto completoBrugada syndrome (BrS) is an inherited autosomal dominant cardiac channelopathy characterized by abnormal ECG pattern and an increased risk of sudden cardiac death. Several mutations on the cardiac sodium channel Nav1.5 which are responsible for BrS lead to misfolded proteins that do not traffic properly to the plasma membrane and are instead retained in intracellular compartments. Although pharmacological rescue is commonly used to characterize misfolded mutants, underlying cellular retention mechanisms remain unclear. The aim of this work is to investigate trafficking defective Nav1.5 mutants considering BrS patient heterozygosity and the presence of the regulatory β1-subunit which is largely expressed in cardiac tissue. By combining electrophysiology and biochemical approaches, we show that three distinct mutants, R1432G, L325R and S910L, exert a strong dominant negative effect upon wild-type (WT) sodium current density. Our data indicate that this effect requires the presence of the β1-subunit and is mediated by disruption of membrane trafficking of WT channels. Co-immunoprecipitation experiments demonstrate a physical interaction between mutant and WT α-subunits occurring only when the β1-subunit was present. Furthermore, we investigate the maturation pattern of Na channels. Our data show distinct N-glycosylated states between WT and mutant channels, suggesting that Nav1.5 α-subunits traffic (i) via unconventional secretion pathway as a partially glycosylated product, (ii) through the classical secretory pathway for mature fully-glycosylated form. This work highlights that β1-subunit and N-linked glycosylation process play key roles in modulating Nav1.5 trafficki
Oliveira, Sarah Almeida Coelho de. "Eficácia do preparo biomecânico utilizando hipoclorito de sódio 1%, clorexidina gel 2% e extrato glicólico de própolis 12%, como substâncias químicas auxiliares sobre o ácido lipoteicóico de Enterococcus faecalis /". São José dos Campos :, 2012. http://hdl.handle.net/11449/90390.
Texto completoBanca: Marcia Carneiro Valera
Banca: Mariella Vieira Pereira Leão
Resumo: Bactérias Gram-positivas presentes nas infecções dos canais radiculares possuem em sua parede celular ácido lipoteicóico (LTA), que apresenta potente ação citotóxica. O objetivo deste estudo foi avaliar a capacidade de substâncias químicas auxiliares como hipoclorito de sódio 1%, clorexidina gel 2%, extrato glicólico de própolis 12%, em neutralizar o ácido lipoteicóico de Enterococcus faecalis em canais radiculares, analisando os efeitos na produção de citocinas (IL-1β, IL-6, TNF-α) por macrófagos (RAW 264.7). Solução salina fisiológica apirogênica 0,9% foi utilizada como controle positivo. Foram utilizadas 40 raízes de dentes unirradiculares padronizadas, distribuídos em 4 grupos (n=10) em placas de poliestireno. Após esterilização, foram inoculados 10μL de uma solução de LTA de Enterococcus faecalis nos canais radiculares por 24h, processo repetido 3 vezes, e posteriormente, realizou-se a instrumentação dos canais radiculares. Foi realizada a coleta do conteúdo imediatamente após a instrumentação. Estas amostras foram utilizadas para verificar se as substâncias químicas apresentavam capacidade de neutralizar o LTA. Para tanto, macrófagos (RAW 264.7) foram ativados com as amostras coletadas dos canais radiculares e os sobrenadantes foram utilizados para verificar a produção de citocinas (IL-1β, IL-6, TNF-α) pelo teste imunoenzimático (ELISA). Os resultados foram analisados estatisticamente (Kruskal-Wallis, e teste de Dunn 5%). Em relação a produção de IL-1β e IL-6, os níveis encontrados nos grupos instrumentados com NaOCl e PRO foram inferiores aos grupos CLX e SS. Em TNF-α todos os grupos experimentais, NaOCl: 1496pg/mL, PRO: 1113pg/mL, CLX: 961pg/mL e SS: 1046pg/mL foram estatisticamente semelhantes entre si (p>0,05). Conclui-se que as substâncias químicas auxiliares testadas: NaOCl e PRO... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The purpose of this study is to assess the ability of 1%sodium hypochlorite, 2%chlorhexidine gel, 12 % glycolic extract of propolis and 0,9%apyrogenic saline physiological solution in the neutralization of the lipoteichoic acid (LTA) derived from Enterococcus faecalis in root canals by analyzing the production of IL-1β,IL-6,TNF-α by macrophages (RAW264.7). For this study, 40 single-rooted roots, standardized to 16mm, were used. The root canals were prepared using a 15K-file and then prepared using rotatory system (BioRaCe) until the working length (15mm); the specimens were distributed in microplates with 10 specimens each. After sterilization, 10μL of E. faecalis LTA solution was used in the root canals, and subsequently was perfomed a root canal instrumentation with rotatory system. The samples were then divided into 4 groups (n=10) on the basis of the irrigating agent used as follows: (a) NaOCl: 1%sodium hypochlorite; (b) CLX: 2%chlorhexidine gel; (c) PRO: 12% glycolic extract of propolis; (d) group SS: 0,9%apyrogenic saline physiological solution. The root canal content was collected immediately after instrumentation to verify the production of IL-1β, IL-6, TNF-α, from the macrophages, tested by ELISA. Results were analyzed statistically by (Kruskal-Wallis test, pvalue = 0.0001 <0.05 and Dunn test 5%). Where it was found that in levels found in the groups instrumented with NaOCl and PRO were lower than CLX and SS. TNF-α in all experimental groups, NaOCl: 1496pg/mL, PRO: 1113pg/mL, CLX: 961pg/mL and SS: 1046pg/mL were statistically similar (p> 0.05). It is concluded that the auxiliary chemicals tested: NaOCl and PRO were effective in neutralizing the lipoteichoic acid (LTA) of E. faecalis in root canals compared with the SS group (positive control). For group CLX cytokine production (IL-1β) and... (Complete abstract click electronic access below)
Mestre
Machado, Jose Lecio. "Avaliação radiografica da obturação de canais laterais artificialmente confeccionados em dentes humanos instrumentados com diferentes substancias auxiliares e obturados pela tecnica da condensação lateral : estudo in vitro". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289890.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-05T02:37:13Z (GMT). No. of bitstreams: 1 Machado_JoseLecio_M.pdf: 638995 bytes, checksum: e590348fae76b970939ad0028be1c3d7 (MD5) Previous issue date: 2005
Resumo: O objetivo deste estudo foi avaliar radiograficamente a obturação de canais laterais artificialmente confeccionados em dentes humanos instrumentados com diferentes substâncias auxiliares e obturados pela técnica da condensação lateral. Dois canais laterais foram confeccionados no terço médio e no terço apical de 40 dentes com uma lima #10. Condensação lateral e o cimento AH Plus foram usados para a obturação dos canais radiculares e radiografias vestíbulo-linguais foram feitas. Diferentes soluções foram usadas para irrigar o canal: Gluconato de Clorexidina gel, Hipoclorito de Sódio, EDTA e Solução salina. Os resultados obtidos não demonstraram diferenças estatísticas. Concluímos que o uso de diferentes substâncias auxiliares no preparo químico-mecânico não influencia a obturação de canais laterais artificialmente confeccionados em dentes humanos quando avaliados radiograficamente
Abstract: The aim of this study was to evaluate if the presence of smear layer interfere the filling of artificial lateral canals. Two lateral canals were produced in the medium and apical third of 40 teeth roots with #10 files. Lateral condensation and AH-Plus sealer were used to fill the root canals and buccolingual radiographs were performed. Different solutions were used to irrigate the canal: Chlorhexidine Gluconate Gel; Sodium Hypochlorite, EDTA and Saline solution. The results did not show any statistical difference. It was concluded that no differences were found among the different substances in used the lateral condensation on the ability to obturated lateral canals artificially in human teeth, in same third or in same groups radiographically
Mestrado
Endodontia
Doutor em Clínica Odontológica
Schaub, Alexander. "Méthodes formelles pour l'analyse de fuites cache-timing et la génération de clés dans les implémentations cryptographiques". Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAT044.
Texto completoCryptography is ubiquitous in today's interconnected world, protecting our communications, securing our payment systems. While the cryptographic algorithms are generally well understood, their implementations have been less subject to formal verification. This has lead to successful breakages of implementions of most modern primitives: AES, RSA, ECDSA... In general, cryptographic implementations would benefit from stronger theoretical guarantees.In this thesis, we apply this line of reasoning to two different topics, one in software security, and the other in hardware security. The first half of this thesis explores cache-timing side channel vulnerabilities that arise when the time taken by a cryptographic operation, or the cache state after this operation, depends on sensitive information. This occurs if any branching operation depends on secret information such as a private key, or if memory is accessed at an address that depends on that secret.We developed a tool to detect and prevent such leaks in programs written in the C programming language. This tool is applied on most candidates of NIST's post-quantum standardization process in order to find cache-timing leakages. This process aims at replacing traditional cryptographic primitives such as RSA or ECDSA, broken by quantum computers, by safer alternatives. The development of such primitives is on the way, but the security of their implementations has received less scrutiny. We show how our tool is able to detect potential cache-timing leaks in a majority of the implementations and what mitigations are possible.The subject of the second half of this thesis are the so-called physically unclonable functions, or PUFs: elementary circuits from which stable but unpredictable identifiers can be extracted. They rely on small, uncontrollable changes in the semiconductor properties to exhibit unpredictable behavior. Theoretical guarantees concerning two fundamental characteristics of PUFs are derived in this thesis, for a large family of PUFs: the stability of the identifier, related to circuit noise, and the exploitable entropy, derived from the mathematical PUF model
Almeida, Braga Daniel de. "Cryptography in the wild : the security of cryptographic implementations". Thesis, Rennes 1, 2022. http://www.theses.fr/2022REN1S067.
Texto completoSide-channel attacks are daunting for cryptographic implementations. Despite past attacks, and the proliferation of verification tools, these attacks still affect many implementations. In this manuscript, we address two aspects of this problem, centered around attack and defense. We unveil several microarchitectural side-channel attacks on implementations of PAKE protocols. In particular, we exposed attacks on Dragonfly, used in the new Wi-Fi standard WPA3, and SRP, deployed in many software such as ProtonMail or Apple HomeKit. We also explored the lack of use by developers of tools to detect such attacks. We questioned developers from various cryptographic projects to identify the origin of this lack. From their answers, we issued recommendations. Finally, in order to stop the spiral of attack-patch on Dragonfly implementations, we provide a formally verified implementation of the cryptographic layer of the protocol, whose execution is secret-independent
Tehrani, Etienne. "Cryptographic primitives adapted to connected car requirements". Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. https://theses.hal.science/tel-03788940.
Texto completoCommunications are one of the key functions in future vehicles and require protection. Cryptography is an obvious answer to secure communications, specifically we studied lightweight cryptography to fit the constrained resources of the environment. A second emerging problem, specific to embedded systems, is resilience to side-channel attacks.The main objectives of the thesis are to study the feasibility of implementing a wide variety of symmetric lightweight encryption algorithms and their protection. An optimal solution is to have an agile implementation, able to quickly execute different lightweight encryption algorithms, using few resources and guaranteeing protection against physical attacks. Our main architecture starts from a modification of the instruction set of a RISC-V processor to satisfy the agility property of lightweight cryptography algorithms. We have studied many encryption algorithms and have proposed a first approach with a fully hardware architecture and a second approach with a dedicated processor in order to efficiently implement Lightweight Cryptography and their protection in a constrained embedded system