Automatic binary deobfuscation

This paper gives an overview of our research in the automation of the process of software protection analysis. We will focus more particularly on the problem of obfuscation. Our current approach is based on a local semantic analysis, which aims to rewrite the binary code in a simpler (easier to understand) way. This approach has the advantage of not relying on a manual search for “patterns” of obfuscation. This way of manipulating the code is, at the end, quite similar to the optimising stage of most of compilers. We will exhibit concrete results based on the development of a prototype and its application to a test target. Current limitations and future prospects will be discussed in as well.     

Push-and-track: Saving infrastructure bandwidth through opportunistic forwarding

Major wireless operators are nowadays facing network capacity issues in striving to meet the growing demands of mobile users. At the same time, 3G-enabled devices increasingly benefit from ad hoc radio connectivity (e.g., WiFi). In this context of hybrid connectivity, we propose Push-and-track, a content dissemination framework that harnesses ad hoc communication opportunities to minimize the load on the wireless infrastructure while guaranteeing tight delivery delays. It achieves this through a control loop that collects user-sent acknowledgements to determine if new copies need to be re-injected into the network through the 3G interface. Push-and-Track is flexible and can be applied to a variety of scenarios, including periodic message flooding and floating data. For the former, this paper examines multiple strategies to determine how many copies of the content should be injected, when, and to whom; for the latter, it examines the achievable offload ratio depending on the freshness constraints. The short delay-tolerance of common content, such as news or road traffic updates, make them suitable for such a system. Use cases with a long delay-tolerance, such as software updates, are an even better fit. Based on a realistic large-scale vehicular dataset from the city of Bologna composed of more than 10,000 vehicles, we demonstrate that Push-and-Track consistently meets its delivery objectives while reducing the use of the 3G network by about 90%.     

Cooperative Metaheuristics for Exploring Proteomic Data

Most combinatorial optimization problems cannotbe solved exactly. A class of methods, calledmetaheuristics, has proved its efficiency togive good approximated solutions in areasonable time. Cooperative metaheuristics area sub-set of metaheuristics, which implies aparallel exploration of the search space byseveral entities with information exchangebetween them. The importance of informationexchange in the optimization process is relatedto the building block hypothesis ofevolutionary algorithms, which is based onthese two questions: what is the pertinentinformation of a given potential solution andhow this information can be shared? Aclassification of cooperative metaheuristicsmethods depending on the nature of cooperationinvolved is presented and the specificproperties of each class, as well as a way tocombine them, is discussed. Severalimprovements in the field of metaheuristics arealso given. In particular, a method to regulatethe use of classical genetic operators and todefine new more pertinent ones is proposed,taking advantage of a building block structuredrepresentation of the explored space. Ahierarchical approach resting on multiplelevels of cooperative metaheuristics is finallypresented, leading to the definition of acomplete concerted cooperation strategy. Someapplications of these concepts to difficultproteomics problems, including automaticprotein identification, biological motifinference and multiple sequence alignment arepresented. For each application, an innovativemethod based on the cooperation concept isgiven and compared with classical approaches.In the protein identification problem, a firstlevel of cooperation using swarm intelligenceis applied to the comparison of massspectrometric data with biological sequencedatabase, followed by a genetic programmingmethod to discover an optimal scoring function.The multiple sequence alignment problem isdecomposed in three steps involving severalevolutionary processes to infer different kindof biological motifs and a concertedcooperation strategy to build the sequencealignment according to their motif content.     

Two dimensional gel electrophoresis of apolipoprotein C‐III and MALDI‐TOF MS are complementary techniques for the study of combined defects in N‐ and mucin type O‐glycan biosynthesis

In the field of diseases related to glycosylation disorders, congenital defects associated with abnormalities in both O‐ and N‐glycosylation of proteins constitute arising novel entities. Defects in subunits of the conserved oligomeric Golgi protein complex have been shown to be involved in an important part of previously unsolved CDG type II combining abnormalities in both mucin type core1 O‐ and N‐glycans; furthermore, recent studies revealed that autosomal recessive cutis laxa type II could also be associated with such combined glycosylation defects. Based on the studies of serum samples from three patients including a case of cutis laxa, we present here evidence that 2‐DE of apolipoprotein C‐III in combination with MALDI‐TOF‐MS analysis of serum O‐ and N‐glycans allow the detection and the biochemical characterization of these newly recognized glycosylation disorders.     

Light and heavy water dynamic structure factor for neutron transport codes

In this study, we report on recent neutron inelastic scattering experiments performed at the Institut Laue-Langevin (ILL) for H₂O and D₂O. The measured dynamic structure factors S(q, ω) have been reduced, normalised and transformed into the S(α, β) formalism, where α and β stand for the unit-less momentum and energy transfers, respectively. The measurements were complemented with molecular dynamics simulations. After processing with NJOY, new water neutron scattering cross-sections have been generated for use with e.g. the Monte Carlo N-Particle (MCNP) software in view to improve the accuracy of the nuclear facility models. As an example, we present improved accuracy calculations for the safety rod insertion impact on the criticality factor k_eff for the ILL high flux research reactor.     

What Currently Limits Charge Carrier Mobility in Crystals of Molecular Semiconductors?

Charge carrier mobility is a central property that characterizes the performances of organic semiconductors and is mostly measured in field-effect transistors. High mobility values are sought by many research teams. This article, that provides an overview of best performing molecular semiconductors is constructed on the question: What currently limits charge carrier mobility in crystals of molecular semiconductors? With this in mind, we confront, in a critical way, the current theoretical understanding to the most salient experimental results with the hope to reach a deeper understanding based on first principles and order of magnitudes of the main physical parameters.     

Experimental design and batch experiments for optimization of Cr(VI) removal from aqueous solutions by hydrous cerium oxide nanoparticles

Hydrous cerium oxide (HCO) was synthesized by intercalation of solutions of cerium(III) nitrate and sodium hydroxide and evaluated as an adsorbent for the removal of hexavalent chromium from aqueous solutions. Simple batch experiments and a 2⁵ factorial experimental design were employed to screen the variables affecting Cr(VI) removal efficiency. The effects of the process variables; solution pH, initial Cr(VI) concentration, temperature, adsorbent dose and ionic strength were examined. Using the experimental results, a linear mathematical model representing the influence of the different variables and their interactions was obtained. Analysis of variance (ANOVA) demonstrated that Cr(VI) adsorption significantly increases with decreased solution pH, initial concentration and amount of adsorbent used (dose), but slightly decreased with an increase in temperature and ionic strength. The optimization study indicates 99% as the maximum removal at pH 2, 20 °C, 1.923 mM of metal concentration and a sorbent dose of 4 g/dm³. At these optimal conditions, Langmuir, Freundlich and Redlich–Peterson isotherm models were obtained. The maximum adsorption capacity of Cr(VI) adsorbed by HCO was 0.828 mmol/g, calculated by the Langmuir isotherm model. Desorption of chromium indicated that the HCO adsorbent can be regenerated using NaOH solution 0.1 M (up to 85%). The adsorption interactions between the surface sites of HCO and the Cr(VI) ions were found to be a combined effect of both anion exchange and surface complexation with the formation of an inner-sphere complex.     

Modeling Polymer Dielectric/Pentacene Interfaces: On the Role of Electrostatic Energy Disorder on Charge Carrier Mobility

Force‐field and quantum‐chemical calculations are combined to model the packing of pentacene molecules at the atomic level on two polymer dielectric layers (poly(methyl methacrylate) (PMMA) versus polystyrene (PS)) widely used in field‐effect transistors and to assess the impact of electrostatic interactions at the interface on the charge mobility values in the pentacene layers. The results show unambiguously that the electrostatic interactions introduce a significant energetic disorder in the pentacene layer in contact with the polymer chains; a drop in the hole mobility by a factor of 5 is predicted with PS chains while a factor of 60 is obtained for PMMA due to the presence of polar carbonyl groups.     

Quantifying the impact of cloud cover on ground radiation flux measurements using hemispherical images

Linking observed or estimated ground incoming solar radiation with cloud coverage is difficult since the latter is usually poorly described in standard meteorological observation protocols. To investigate the benefits of detailed observation and characterization of cloud coverage and distribution, a fieldwork campaign has been set up in order to collect data about cloud cover conditions and daily evolution to directly analyse their impacts on solar radiation fluxes. To do so, daytime hemispherical images have been collected at a very high frequency, simultaneously to ground measurements of solar radiation fluxes in a scientific station close to Lake NamCo, China. After calibration, one of the main tasks was the classification of those hemispherical images and the extraction of meaningful indices to describe the cloud cover, such as cloud fraction or cloud cover distribution. The classification is based on automatic detection of threshold on the red channel histogram. The results show that several cloud indices could be successfully derived from the hemispherical images, even if very thin clouds can be difficult to detect. The indices are then correlated to the measured solar radiation values and the impact of cloud cover on surface radiation fluxes were analysed. This analysis highlights that, more than the cloud fraction, the cloud distribution in the hemisphere is of importance when modelling radiation fluxes in the solar domain.