Acoustic response of a rigid frame porous medium slab with a periodic set of inclusions

The acoustic response of a rigid frame porous slab with a periodic set of inclusions is calculated by use of a multipole method. The acoustic properties, in particular the absorption, of such a structure are then derived and studied. Numerical results together with a modal analysis show that the addition of a periodic set of high-contrast inclusions leads to quasi-modes excitation of both the slab and the gratings, and to a large increase of the acoustic absorption of the initial slab, this being partly due to the quasi-modes excitation.Comment: submitted to Journal of Sound and Vibratio

Propagation of acoustic waves in a one-dimensional macroscopically inhomogeneous poroelastic material

International audienceWave propagation in macroscopically inhomogeneous porous materials has received much attention in recent years. The wave equation, derived from the alternative formulation of Biot's theory of 1962, was reduced and solved recently in the case of rigid frame inhomogeneous porous materials. This paper focuses on the solution of the full wave equation in which the acoustic and the elastic properties of the poroelastic material vary in one-dimension. The reflection coefficient of a one-dimensional macroscopically inhomogeneous porous material on a rigid backing is obtained numerically using the state vector (or the so-called Stroh) formalism and Peano series. This coefficient can then be used to straightforwardly calculate the scattered field. To validate the method of resolution, results obtained by the present method are compared to those calculated by the classical transfer matrix method at both normal and oblique incidence and to experimental measurements at normal incidence for a known two-layers porous material, considered as a single inhomogeneous layer. Finally, discussion about the absorption coefficient for various inhomogeneity profiles gives further perspectives

Reconstruction of material properties profiles in one-dimensional macroscopically inhomogeneous rigid frame porous media in the frequency domain

International audienceThe present paper deals with the inverse scattering problem involving macroscopically inhomogeneous rigid frame porous media. It consists of the recovery, from acoustic measurements, of the profiles of spatially varying material parameters by means of an optimization approach. The resolution is based on the modeling of acoustic wave propagation in macroscopically inhomogeneous rigid frame porous materials, which was recently derived from the generalized Biot's theory. In practice, the inverse problem is solved by minimizing an objective function defined in the least-square sense by the comparison of the calculated reflection ͑and transmission͒ coefficient͑s͒ with the measured or synthetic one͑s͒, affected or not by additive Gaussian noise. From an initial guess, the profiles of the x-dependent material parameters are reconstructed iteratively with the help of a standard conjugate gradient method. The convergence rate of the latter and the accuracy of the reconstructions are improved by the availability of an analytical gradient

Non-typeable Haemophilus influenzae protein vaccine in adults with COPD:A phase 2 clinical trial

Loss of airway microbial diversity is associated with non-typeable Haemophilus influenzae (NTHi) infection and increased risk of exacerbation in chronic obstructive pulmonary disease (COPD). We assessed the safety and immunogenicity of an investigational vaccine containing NTHi antigens, recombinant protein D (PD) and combined protein E and Pilin A (PE-PilA), and AS01 adjuvant in adults with moderate/-severe COPD and prior exacerbations. In this phase 2, observer-blind, controlled trial (NCT02075541), 145 COPD patients aged 40-80 years randomly (1:1) received two doses of NTHi vaccine or placebo 60 days apart, on top of standard care. Reactogenicity in the 7-day post-vaccination period was higher following NTHi vaccine than placebo. Most solicited adverse events (AEs) were mild/moderate. At least one unsolicited AE was reported during the 30-day post-vaccination period by 54.8% of NTHi vaccine and 51.4% of placebo recipients. One serious AE (placebo group) was assessed by the investigator as vaccine-related. Anti-PD, anti-PE and anti-PiIA geometric mean antibody concentrations increased up to 30 days after each NTHi vaccine dose, waned thereafter, but remained higher than baseline (non-overlapping confidence intervals) up to 13 months post-dose 2. The frequency of specific CD4(+) T cells increased following two doses of NTHi vaccine and remained higher than baseline. Exploratory analysis showed a statistically non-significant lower yearly rate of moderate/severe exacerbations in the NTHi vaccine group than following placebo (1.49 versus 1.73) in the one-year period post-dose 2, with estimated vaccine efficacy of 13.3% (95% confidence interval -24.2 to 39.5; p = 0.44). The NTHi vaccine had an acceptable safety and reactogenicity profile and good immunogenicity in adults with COPD

CsFire: Browser-enforced mitigation against CSRF

Cross-Site Request Forgery (CSRF) is a web application attack vector that can be leveraged by an attacker to force an unwitting user's browser to perform actions on a third party website, possibly reusing all cached authentication credentials of that user. Currently, a whole range of techniques exist to mitigate CSRF, either by protecting the server application or by protecting the end-user. Unfortunately, the server-side protection mechanisms are not yet widely adopted, and the client-side solutions provide only limited protection or cannot deal with complex web 2.0 applications, which use techniques such as AJAX, mashups or single sign-on (SSO). In this talk, we will presents three interesting results of our research: (1) an extensive, real‐world traffic analysis to gain more insights in cross‐domain web interactions, (2) requirements for client‐side mitigation against CSRF and an analysis of existing browser extensions and (3) CsFire, our newly developed FireFox extension to mitigate CSRF.status: publishe

CsFire: browser-enforced mitigation against CSRF

In this talk, we will presents three interesting results of our research: (1) an extensive, real-world traffic analysis to gain more insights in cross-domain web interactions, (2) requirements for client-side mitigation against CSRF and an analysis of existing browser extensions and (3) CsFire , our newly developed FireFox extension to mitigate CSRF.status: publishe

Middleware support for complex and distributed security services in multi-tier web applications

The security requirements of complex multi-tier web appli- cations have shifted from simple localized needs, such as authentication or authorization, to physically distributed but actually aggregated ser- vices, such as end-to-end data protection, non-repudiation or patient consent management. Currently, there is no support for integrating com- plex security services in web architectures, nor are approaches from other architectural models easily portable. In this paper we present the archi- tecture of a security middleware, aimed at providing a reusable solution bringing support for complex security requirements into the application architecture, while addressing typical web architecture challenges, such as the tiered model or the lack of sophisticated client-side logic. We both evaluate the security of the middleware and present a case study and prototype implementation, which show how the complexities of a web architecture can be dealt with while limiting the integration effort.status: publishe

A security analysis of emerging web standards - Extended version

Over the past few years, a significant effort went into the development of a new generation of web standards, centered around the HTML5 specification. Given the importance of the web in our society, it is essential that these new standards are scrutinized for potential security problems. This paper reports on a systematic analysis of ten important, recent specifications with respect to two generic security goals: (1) new web mechanisms should not break the security of existing web applications, and (2) different newly proposed mechanisms should interact with each other gracefully. Our analysis reveals several violations of these security goals, which should be addressed by the specifications. In addition, we analyze the implementations of some of these standards in major browsers, and show that (1) even explicit security considerations in the standards are not consistently implemented, and (2) ambiguities and under-specification in the standards lead to suboptimal browser implementations. In total, the security analysis reveals 45 issues, of which 12 are violations of the proposed security goals and 31 issues concern vague and ambiguous features in the specifications. Additionally, we found that 6 out of 11 explicit security considerations have been overlooked/overruled in major browsers, leaving secure specifications vulnerable in the end.nrpages: 14status: publishe

TabShots: Client-side detection of tabnabbing attacks

As the web grows larger and larger and as the browser becomes the vehicle-of-choice for delivering many applications of daily use, the security and privacy of web users is under constant attack. Phishing is as prevalent as ever, with anti-phishing communities reporting thousands of new phishing campaigns each month. In 2010, tabnabbing, a variation of phishing, was introduced. In a tabnabbing attack, an innocuous-looking page, opened in a browser tab, disguises itself as the login page of a popular web application, when the user's focus is on a different tab. The attack exploits the trust of users for already opened pages and the user habit of long-lived browser tabs. To combat this recent attack, we propose TabShots. TabShots is a browser extension that helps browsers and users to remember what each tab looked like, before the user changed tabs. Our system compares the appearance of each tab and highlights the parts that were changed, allowing the user to distinguish between legitimate changes and malicious masquerading. Using an experimental evaluation on the most popular sites of the Internet, we show that TabShots has no impact on 78% of these sites, and very little on another 19%. Thereby, TabShots effectively protects users against tabnabbing attacks without affecting their browsing habits and without breaking legitimate popular sites.status: publishe