A constraint-based WCET computation framework

National audienceOTAWA is a tool dedicated to the WCET computation of critical real-time systems. The tool was enhanced in order to take into account modern micro-architecture features, through an ADL-based approach. Architecture constraints are expresses such that they can be solved by well known efficient constraint solvers. In this paper, we present how we could describe some complex architecture features using the Sim-nML language. We are also concerned by the validation and the animation point of views

Formal Architecture Specification for Time Analysis

International audienceWCET calculus is nowadays a must for safety critical systems. As a matter of fact, basic real-time properties rely on accurate timings. Although over the last years, substantial progress has been made in order to get a more precise WCET, we believe that the design of the underlying frameworks deserve more attention. In this paper, we are concerned mainly with two aspects which deal with the modularity of these frameworks. First, we enhance the existing language Sim-nML for describing processors at the instruction level in order to capture modern architecture aspects. Second, we propose a light DSL in order to describe, in a formal prose, architectural aspects related to both the structural aspects as well as to the behavioral aspects

New long-lived particle searches in heavy-ion collisions at the LHC

We show that heavy-ion collisions at the LHC provide a promising environment to search for signatures with displaced vertices in well-motivated new physics scenarios. Compared to proton collisions, they offer several advantages: (i) the number of parton level interactions per collision is larger, (ii) there is no pileup, (iii) the lower instantaneous luminosity compared to proton collisions allows one to operate the LHC experiments with very loose triggers, and (iv) there are new production mechanisms that are absent in proton collisions We focus on the third point and show that the modification of the triggers alone can increase the number of observable events by orders of magnitude if the long-lived particles are predominantly produced with low transverse momentum. Our results show that collisions of ions lighter than lead are well motivated from the viewpoint of searches for new physics. We illustrate this for the example of heavy neutrinos in the Neutrino Minimal Standard Model

Hardware architecture specification and constraint-based WCET computation

International audienceThe analysis of the worst-case execution times is necessary in the design of critical real-time systems. To get sound and precise times, the WCET analysis for these systems must be performed on binary code and based on static analysis. OTAWA, a tool providing WCET computation, uses the Sim-nML language to describe the instruction set and XML files to describe the microarchitecture. The latter information is usually inadequate to describe real architectures and, therefore, requires specific modifications, currently performed by hand, to allow correct time calculation. In this paper, we propose to extend Sim-nML in order to support the description of modern microarchitecture features along the instruction set description and to seamlessly derive the time calculation. This time computation is specified as a constraint solving problem that is automatically synthesized from the extended Sim-nML. Thanks to its declarative aspect, this approach makes easier and modular the description of complex features of microprocessors while maintaining a sound process to compute times

Répression transcriptionnelle du gène TRH

Les hormones thyroïdiennes (HT : T3, T4) exerçant des effets pléiotropes chez les vertébrés, leur synthèse et leur sécrétion doivent être finement contrôlées. Elles agissent elles-mêmes sur leur production, par un système de rétrocontrôle négatif de l’expression des gènes hypothalamique TRH et hypophysaire TSH. Les fondements moléculaires de cette répression transcriptionnelle des gènes TRH et TSH par l’hormone T3, forme biologiquement la plus active des HT, restent méconnus. Certaines caractéristiques de cette régulation commencent toutefois à être identifiées, notamment le rôle spécifique des isoformes TRβ (versus TRα) des récepteurs des HT. La spécificité fonctionnelle de ces isoformes résiderait principalement dans leur extrémité aminoterminale, qui permettrait une interaction différentielle avec certains comodulateurs. L’objectif, aujourd’hui, est de caractériser ces comodulateurs et d’analyser leur contribution à la régulation transcriptionnelle du gène TRH par l’hormone T3.The synthesis and secretion of thyroid hormones (TH: T3, T4) must be strictly regulated. TH act on their own production via a negative feedback system. The synthesis of thyrotropin-releasing hormone (TRH), produced in the hypothalamus, and thyrotropin (TSH) in the pituitary is inhibited at the transcriptional level by TH. TRH and TSH stimulate production of TH. An outstanding, still open, question is the molecular basis of T3-dependent transcription repression of TRH and TSH genes. However, some regulatory components have been identified, with the β-TH receptor (TRβ) playing a specific regulatory role (versus TRα) in the negative feedback effects of T3 on production of TRH and TSH. Moreover, the N-terminus of TRβ is known to be a key element in this regulation. A hypothesis to explain this isoform specificity could be that TRβ and TRα interact differentially with transcriptional comodulators. Thus, it is critical to characterize these comodulators and to analyse their contribution to the transcription regulation of TRH

Heavy neutrino-antineutrino oscillations at the FCC-ee

We discuss the impact of heavy neutrino-antineutrino oscillations (NNOs) on heavy neutral lepton (HNL) searches at proposed electron-positron colliders such as the future circular $e^+e^-$ collider (FCC-ee). During the $Z$ pole run, HNLs can be produced alongside a light neutrino or antineutrino that escapes detection and can decay into a charged lepton or antilepton together with an off-shell $W$ boson. In this case, signals of lepton number violation only show up in the final state distributions. We discuss how NNOs, a typical feature of collider-testable low-scale seesaw models where the heavy neutrinos form pseudo-Dirac pairs, modify such final state distributions. For example, the forward-backward asymmetry (FBA) of the reconstructed heavy (anti)neutrinos develops an oscillatory dependence on the HNL lifetime. We show that these oscillations can be resolvable for long-lived HNLs. We also discuss that when the NNOs are not resolvable, they can nevertheless significantly modify the theory predictions for FBAs and observables such as the ratio of the total number of HNL decays into $\ell^-$ over ones into $\ell^+$, in an interval of the angle~$\theta$ between the HNL and the beam axis. Our results show that NNOs should be included in collider simulations of HNLs at the FCCee.Comment: 14 pages, 3 figure

Synthesis and characterization of biocompatible methacrylated Kefiran hydrogels: towards tissue engineering applications

Hydrogel application feasibility is still limited mainly due to their low mechanical strength and fragile nature. Therefore, several physical and chemical cross-linking modifications are being used to improve their properties. In this research, methacrylated Kefiran was synthesized by reacting Kefiran with methacrylic anhydride (MA). The developed MA-Kefiran was physicochemically characterized, and its biological properties evaluated by different techniques. Chemical modification of MA-Kefiran was confirmed by 1H-NMR and FTIR and GPC-SEC showed an average Mw of 793 kDa (PDI 1.3). The mechanical data obtained revealed MA-Kefiran to be a pseudoplastic fluid with an extrusion force of 11.21 ± 2.87 N. Moreover, MA-Kefiran 3D cryogels were successfully developed and fully characterized. Through micro-CT and SEM, the scaffolds revealed high porosity (85.53 ± 0.15%) and pore size (33.67 ± 3.13 μm), thick pore walls (11.92 ± 0.44 μm) and a homogeneous structure. Finally, MA-Kefiran revealed to be biocompatible by presenting no hemolytic activity and an improved cellular function of L929 cells observed through the AlamarBlue® assay. By incorporating methacrylate groups in the Kefiran polysaccharide chain, a MA-Kefiran product was developed with remarkable physical, mechanical, and biological properties, resulting in a promising hydrogel to be used in tissue engineering and regenerative medicine applications.H. Radhouani and C. Goncalveswere supported by the Foundation for Science and Technology (FCT) fromPortugal, with references CEECIND/00111/2017 and SFRH/BPD/94277/2013, respectively. S. Correia and this work were funded by the R&D Project KOAT-Kefiran Exopolysaccharide: Promising Biopolymer for Use in Regenerative Medicine and Tissue Engineering, with reference PTDC/BTMMAT/29760/2017 (POCI-01-0145-FEDER-029760), financed by FCT and co-financed by FEDER and POCI. We also thank Duarte N. Carvalho for input on the schematic representation of the process