4 research outputs found
Structure to function studies in UDP-glucose dehydrogenases and nitroreductases
The thesis is divided into two parts corresponding to structural studies on two
different proteins. The first part concerns the study of two UDP-glucose
dehydrogenases (UGDs) from Sphingomonas elodea ATCC 31461 and
Burkholderia cepacia IST 408, both involved in exopolysaccharide production.
Their relevance arises because some of these bacterial exopolysaccharides are
valuable as established biotechnological products, the former case, whilst others
are highly problematic, when used by pathogens in biofilm formation over
biological surfaces, as the latter case, namely in the human lungs. The goal of
these studies is to increase our knowledge regarding UGDs structural
properties, which can potentiate either the design of activity enhancers to
respond to the increased demand of useful biofilms, or the design of inhibitors
of biofilm production, in order to fight invading pathogens present in several
infections. The thesis reports the production and crystallisation of both proteins,
the determination of initial phases by single-wavelength anomalous dispersion
(SAD) in S. elodea crystals using a seleno-methionine isoform, and phasing of
B. cepacia crystals by molecular replacement (MR) using the S. elodea model,
as well as the refinement, structural analysis and comparison between the
several UGDs structures available during this work.(...
Non-Intrusive Subscriber Authentication for Next Generation Mobile Communication Systems
Merged with duplicate record 10026.1/753 on 14.03.2017 by CS (TIS)The last decade has witnessed massive growth in both the technological development, and
the consumer adoption of mobile devices such as mobile handsets and PDAs. The recent
introduction of wideband mobile networks has enabled the deployment of new services
with access to traditionally well protected personal data, such as banking details or
medical records. Secure user access to this data has however remained a function of the
mobile device's authentication system, which is only protected from masquerade abuse by
the traditional PIN, originally designed to protect against telephony abuse.
This thesis presents novel research in relation to advanced subscriber authentication for
mobile devices. The research began by assessing the threat of masquerade attacks on
such devices by way of a survey of end users. This revealed that the current methods of
mobile authentication remain extensively unused, leaving terminals highly vulnerable to
masquerade attack. Further investigation revealed that, in the context of the more
advanced wideband enabled services, users are receptive to many advanced
authentication techniques and principles, including the discipline of biometrics which
naturally lends itself to the area of advanced subscriber based authentication.
To address the requirement for a more personal authentication capable of being applied
in a continuous context, a novel non-intrusive biometric authentication technique was
conceived, drawn from the discrete disciplines of biometrics and Auditory Evoked
Responses. The technique forms a hybrid multi-modal biometric where variations in the
behavioural stimulus of the human voice (due to the propagation effects of acoustic
waves within the human head), are used to verify the identity o f a user. The resulting
approach is known as the Head Authentication Technique (HAT).
Evaluation of the HAT authentication process is realised in two stages. Firstly, the
generic authentication procedures of registration and verification are automated within a
prototype implementation. Secondly, a HAT demonstrator is used to evaluate the
authentication process through a series of experimental trials involving a representative
user community. The results from the trials confirm that multiple HAT samples from
the same user exhibit a high degree of correlation, yet samples between users exhibit a
high degree of discrepancy. Statistical analysis of the prototypes performance realised
early system error rates of; FNMR = 6% and FMR = 0.025%. The results clearly
demonstrate the authentication capabilities of this novel biometric approach and the
contribution this new work can make to the protection of subscriber data in next
generation mobile networks.Orange Personal Communication Services Lt
Etudes fonctionnelles et structurales des complexes Hélicase-Primase du virus Epstein-Barr
Le virus Epstein-Barr (EBV) est un gamma herpèsvirus humain infectant plus de 95 % de la population mondiale. Lorsque la primo-infection a lieu pendant l'adolescence ou à l'âge adulte, elle peut induire la mononucléose infectieuse (MNI), cette maladie est le plus souvent bénigne. EBV est aussi associé à un certain nombre de cancers de type lymphome (lymphomes de Burkitt et d'Hodgkin) et de type carcinome (carcinomes gastriques et indifférenciés du rhinopharynx). L'importance des protéines de latence du virus dans l'apparition des tumeurs a été très étudiée. Des études récentes montrent que les protéines lytiques d'EBV sont aussi très importantes pour l'apparition et le développement des tumeurs. Le complexe Hélicase-Primase (H-P) du virus herpès simplex 1 (HSV-1, alpha herpèsvirus) est la cible de nouveaux antiviraux. Les activités ATPase, hélicase et primase du complexe d'HSV-1 ont été largement étudiées, mais aucune information structurale du complexe H-P n'est disponible actuellement pour un membre des herpèsvirus humains. Nous avons entrepris l'étude du complexe H-P d'EBV (BBLF4 : hélicase, BSLF1 : primase et BBLF2/3 : sous-unité accessoire) afin de caractériser sa structure et les activités qu'il porte. Nous avons pu établir les conditions d'expression et de purification du complexe et débuter des études structurales et enzymatiques préliminaires. Nous avons pu observer une activité ATPase basale du complexe indépendante de la présence d'un substrat ADN simple brin. Nous observons deux formes solubles du complexe lors des purifications, une présentant probablement une stœchiométrie proche de 1/1/1 et une seconde forme ayant surement un excès de la protéine Hélicase (BBLF4). Ces premiers résultats apportent des informations nouvelles pour le complexe H-P d'EBV et doivent être poursuivis afin de les confirmer et de pouvoir les comparer avec ceux déjà connus pour le complexe H-P d'HSV-1.Epstein-Barr Virus (EBV) is a human herpesvirus largely present worldwide. When primary infection occurs during adolescence or adulthood, it could cause infectious mononucleosis (IM). This disease is most of the time minor. EBV is also associated with several cancers like lymphomas (Burkitt's lymphoma and Hodgkin's lymphoma) or carcinomas (gastric carcinoma and nasopharyngeal carcinoma). Latent proteins of the virus are largely studied and are important for apparition of tumors. Recent studies show that lytic proteins are also important for tumor apparition and progression. The Helicase-Primase complex (H-P) of herpes simplex 1 (HSV-1), a well-known herpèsvirus, is a target for new antiviral drugs. ATPase, helicase and primase activities of HSV-1 complex are well studied, but no information is available for the structure of the H-P complex of human herpesvirus. We studied the H-P complex of EBV (BBLF4: helicase, BSLF1: primase and BBLF2/3: accessory subunit) to characterize its structure and enzymatic activities. We describe the expression and purification conditions and begin preliminary studies on structure and activities of the H-P complex. We show a basal ATPase activity that is DNA single strand independent. We were able to purify two forms of the H-P complex, the first has a stoichiometry close to 1/1/1 and the second one has an excess of helicase protein (BBLF4). These preliminary results on H-P complex of EBV have to be validated with other experiments before being compared to information already known for the HSV-1 complex. Key words : EBV, Helicase-Primase complex, BBLF4, BSLF1, BBLF2/3, ATPase, stoichiometry.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF
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NCPV FY 1998 Annual Report
This report summarizes the in-house and subcontracted research and development (R and D) activities under the National Center for Photovoltaics (NCPV) from October 1, 1997 through September 30, 1998 (FY 1998). The NCPV is part of the U.S. Department of Energy's (DOE's) National Photovoltaics Program, as described in the DOE National Photovoltaics Program Plan for 1996-2000. The mission of the DOE National Photovoltaics Program is to make PV a significant part of the domestic economy--as an industry and as an energy resource. The two primary goals of the national program are to (1) maintain the U.S. industry's world leadership in research and technology development and (2) help the U.S. industry remain a major, profitable force in the world market. The NCPV provides leadership and support to the national program toward achieving its mission and goals