Apprivoiser l'hétérogénéité en informatique 1ère année

National audienceFace au constat d’une hétérogénéité grandissante des savoir-faire et connaissances en informatique des étudiants à l’arrivée en première année, et le risque de son exacerbation dans le contexte du « nouveau bac », nous avons voulu expérimenter une approche pédagogique, qui permette une gestion de cette hétérogénéité tout en respectant les contraintes d’un emploi du temps homogène et un coût constant. Les actions menées s’articulent autour de 4 pôles : la constitution de groupes de niveau, avec une attention particulière portée sur les 2 niveaux extrêmes (renforcement et avancé/en autonomie), la mise en place de QCMs réguliers, l’utilisation ponctuelle de l’Apprentissage Par Problème (APP), et un auto-positionnement. L’expérimentation est encore en cours, mais déjà de premiers éléments permettent d’ouvrir les échanges

Global Retinoblastoma Presentation and Analysis by National Income Level.

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs

Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries

BACKGROUND: The travel distance from home to a treatment centre, which may impact the stage at diagnosis, has not been investigated for retinoblastoma, the most common childhood eye cancer. We aimed to investigate the travel burden and its impact on clinical presentation in a large sample of patients with retinoblastoma from Africa and Europe. METHODS: A cross-sectional analysis including 518 treatment-naïve patients with retinoblastoma residing in 40 European countries and 1024 treatment-naïve patients with retinoblastoma residing in 43 African countries. RESULTS: Capture rate was 42.2% of expected patients from Africa and 108.8% from Europe. African patients were older (95% CI -12.4 to -5.4, p<0.001), had fewer cases of familial retinoblastoma (95% CI 2.0 to 5.3, p<0.001) and presented with more advanced disease (95% CI 6.0 to 9.8, p<0.001); 43.4% and 15.4% of Africans had extraocular retinoblastoma and distant metastasis at the time of diagnosis, respectively, compared to 2.9% and 1.0% of the Europeans. To reach a retinoblastoma centre, European patients travelled 421.8 km compared to Africans who travelled 185.7 km (p<0.001). On regression analysis, lower-national income level, African residence and older age (p<0.001), but not travel distance (p=0.19), were risk factors for advanced disease. CONCLUSIONS: Fewer than half the expected number of patients with retinoblastoma presented to African referral centres in 2017, suggesting poor awareness or other barriers to access. Despite the relatively shorter distance travelled by African patients, they presented with later-stage disease. Health education about retinoblastoma is needed for carers and health workers in Africa in order to increase capture rate and promote early referral

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Towards a trust-manager service for hybrid clouds.

7p.International audienceCloud computing changed recently business view regarding their Information System through an on-demand provisioning of computing resources. Recent discussions about data security requirements in cloud computing environment tend to conflict with other requirement including usability and economic. In hy-brid clouds that combine private and public clouds usage, private clouds are able both to externalize resources and invoke services from public cloud when needed. However, in such specific inter-cloud environment risks arise. Indeed, private clouds aren't sufficiently assured about how credible is the data computed by these resources they entrusted. This is due to clouds autonomy preservation, difference in control policy definitions and lack of transparency in clouds. In this position paper, we tend to propose an approach to help private cloud selecting a trustworthy public cloud service. The idea consists in a trust manager as a service that bases the decision-making on the private cloud past invocation analysi

A trust management solution in the context of hybrid clouds

International audienceCloud computing is a revolutionary paradigm which enables on-demand provisioning of computing resources. Resources are delivered to cloud consumers in the form of infrastructure, platform and software services. These resources are deployed on three different models: private clouds, public clouds and hybrid clouds. In hybrid cloud context, private clouds externalize resources and invoke services from a public cloud when needed. However, in such a specific inter-cloud environment risks may arise. In fact, private cloud users often interact with cloud providers for services provisioning such as infrastructure, platforms and software. However, they are not sufficiently assured about how credible the data computed by these resources they have entrusted. This is due to clouds autonomy preservation, difference in control policy definitions and lack of transparency in clouds. In this paper, we propose a preventive/detective approach for assessing private cloud to select a trustworthy public cloud service. The solution is based on a mediation as a service that ensures the role of trust manager for the private cloud

Ensuring XML Integrity Using Watermarking Techniques

International audienceToday, XML is the most used data interchange format for business-to-business applications. Indeed, an increasing amount of data in XML format is created and published over the Internet every day. Moreover, organizations need more and more to share sets of XML documents usually managed via a common XML repository. XML integrity and authenticity have become strong requirements for applications like web services that exchange messages in such format. XML signature aims to guarantee these properties but it cannot avoid attackers to intercept and change the structure of the XML message. A very common attack to XML Signature called XML Signature Wrapping(XSW) attack represents a big issue in web services security as SOAP messages –which are XML signed files- could be corrupted. In this paper, we propose a countermeasure to the XML Signature wrapping attack that makes use of XML watermarking techniques. In our proposal we express constraints on the schema of the XML document and fix its structure using an absolute coordinate system whose values are embedded within the file as a watermark

Self organizing inter-grids virtual organization

National audienceThe pervasive grid environment aim at combining the great computing capabilitiesof grid with the mobility capabilities of pervasive systems. The concept of pervasive grid impliesthe multiplication of users, and consequently of applications and needs. Thus, this mergingmake the integration of several heterogeneous platforms critical, especially in a context oftemporary and dynamic collaborations. Our approach consists, instead of homogenizing themiddlewares, in allowing several of them to interact into heterogeneous and dynamic virtualorganization (VO), called inter grid VO. This article focuses on the data management in thiskind of VO, and more precisely on monitoring information, which are both critical to the managementof the plateforms, and highly frequently updated. Our proposal is a an autonomousand self-organized virtual network architecture able to quiclky desseminate data while limitingthe network consumption. The efficiency of our approach as been proved on the experimentalplatform Grid 5000

Self organizing inter-grids virtual organization

National audienceThe pervasive grid environment aim at combining the great computing capabilitiesof grid with the mobility capabilities of pervasive systems. The concept of pervasive grid impliesthe multiplication of users, and consequently of applications and needs. Thus, this mergingmake the integration of several heterogeneous platforms critical, especially in a context oftemporary and dynamic collaborations. Our approach consists, instead of homogenizing themiddlewares, in allowing several of them to interact into heterogeneous and dynamic virtualorganization (VO), called inter grid VO. This article focuses on the data management in thiskind of VO, and more precisely on monitoring information, which are both critical to the managementof the plateforms, and highly frequently updated. Our proposal is a an autonomousand self-organized virtual network architecture able to quiclky desseminate data while limitingthe network consumption. The efficiency of our approach as been proved on the experimentalplatform Grid 5000

Robust XML Watermarking Using Fuzzy Queries

International audienceXML is today the most used data interchange format for business-to-business applications. Indeed, an increasing amount of data is created and published over the Internet every day in XML format. Moreover, organizations need more and more to share sets of XML documents usually managed via a common XML repository. XML copyright protection and source tracking have become strong requirements for collaborative environments. In the literature, XML-specific fingerprinting mechanisms have been proposed, inspired by similar work on relational data. However their robustness is impaired by the fact that an XML file can undergo a set of updates that change both the file structure and content. In this paper, we propose a novel watermarking schema for XML files. This solution is based first on an adequate selection of XML locators, i.e. document fragments targeted to embed the watermark. Watermark retrieval is achieved thank to a set of personalized fuzzy queries that reconstruct the locators that contain the watermark. We show theoretically the watermark robustness against possible XML file transformations; then, we present some initial experiments that validate the approach