Jurnal Edukasi
Not a member yet
4879 research outputs found
Sort by
Une coupe très intéressante dans l'éponge de Menger -itération 5-
No full textAn interesting cross-section inside the Menger sponge -iteration 5- (Une coupe très intéressante dans l'éponge de Menger -itération 5-
Trapping and release of giant unilamellar vesicles in microfluidic wells
No full textInternational audienceWe describe the trapping and release of giant unilamellar vesicles (GUVs) in a thin and wide microfluidic channel, as they cross indentations etched in the channel ceiling. This trapping results from the reduction of the membrane elastic energy, which is stored in the GUV as it squeezes to enter into the thin channel. We demonstrate that GUVs whose diameter is slightly larger than the channel height can be trapped and that they can be untrapped by flowing the outer fluid beyond a critical velocity. GUVs smaller than the channel height flow undisturbed while those much larger cannot squeeze into the thin regions. Within the range that allows trapping, larger GUVs are anchored more strongly than smaller GUVs. The ability to trap vesicles provides optical access to the GUVs for extended periods of time; this allows the observation of recirculation flows on the surface of the GUVs, in the forward direction near the mid-plane of the channel and in the reverse direction elsewhere. We also obtain the shape of GUVs under different flow conditions through confocal microscopy. This geometric information is used to derive a mechanical model of the force balance that equates the viscous effects from the outer flow with the elastic effects based on the variation of the membrane stretching energy. This model yields good agreement with the experimental data when values of the stretching moduli are taken from the scientific literature. This microfluidic approach provides a new way of storing a large number of GUVs at specific locations, with or without the presence of an outer flow. As such, it constitutes a high-throughput alternative to micropipette manipulation of individual GUVs for chemical or biological applications
Decay of Bogoliubov quasiparticles in a nonideal one-dimensional Bose gas
No full textfour pages, one figureInternational audienceWe study the relaxation of excitations in a system of one-dimensional weakly interacting bosons. Due to residual weak interactions, Bogoliubov quasiparticles in this system have finite lifetimes. As a result of the conservation laws in one dimension, at zero temperature the leading mechanism of decay of a quasiparticle is disintegration into three others. We focus on phonon quasiparticles and find that their decay rate is proportional to the seventh power of momentum. In the integrable case of contact interaction between the bosons, the decay rate vanishes
Breast cancer and quality of life: medical information extraction from health forums
No full textInternational audienceInternet health forums are a rich textual resource with content generated through free exchanges among patients and, in certain cases, health professionals. We tackle the problem of retrieving clinically relevant information from such forums, with relevant topics being defined from clinical auto-questionnaires. Texts in forums are largely unstructured and noisy, calling for adapted preprocessing and query methods. We minimize the number of false negatives in queries by using a synonym tool to achieve query expansion of initial topic keywords. To avoid false positives, we propose a new measure based on a statistical comparison of frequent co-occurrences in a large reference corpus (Web) to keep only relevant expansions. Our work is motivated by a study of breast cancer patients' health-related quality of life (QoL). We consider topics defined from a breast-cancer specific QoL-questionnaire. We quantify and structure occurrences in posts of a specialized French forum and outline important future developments
Progress in warm dense matter study with applications to planetology
No full textInternational audienceWe present an overview of some recent theoretical and experimental results obtained on the properties of iron and silica at conditions encountered in planetary interiors. The first part is concerned with the development of x-ray absorption near edge spectroscopy in dynamical experiments using high-energy lasers as a tool to investigate phase transitions and structural changes at extreme pressure-temperature conditions for these two key constituents. The second part focuses on the development of a quasi-isentropic compression technique to achieve the pressure-temperature conditions anticipated in planetary interiors (3-10 Mbar, 5000-8000 K). The experiments were performed using the LULI, LLNL and LIL high-energy lasers' facilities. The experimental results are analyzed using first-principle simulations based on density functional theory
Spectroscopic analysis of X-pinch plasma produced on the compact LC-generator of Ecole Polytechnique using artificial neural networks
No full textInternational audienceA back-propagation artificial neural network algorithm is applied to a Mo X-pinch to estimate plasma parameters from typical L-shell spectra in the keV region. The spectrum was generated by a very compact LC-generator (40 kV, 200 kA) for driving 25-μm Mo two-wire X-pinches with a current rise-time of 200 ns. The neural network was trained over a set of synthetic spectra generated using a previously developed L-shell non-LTE collisionally radiative model. As a result, electron temperature and density of the Mo plasma were estimated as Te = 1000 eV and ne = 9 × 1020 cm−3. Furthermore, effects of electron beams on plasma parameters have been investigated through the inclusion of hot electrons in the kinetic model. The small fraction of hot electrons resulted in a better fitting of spectrum and decreased parameters Te = 650 eV and ne = 3 × 1020 cm−3
A linearized approach for the control of aerodynamic forces in flow past a square cylinder
No full textInternational audienceno abstrac
What should 'majority decision' mean?
No full textInternational audienceThis book presents the most complete set of analytical, normative, and historical discussions of majority decision making to date
Structure et propriétés électroniques de monocouches organiques autoassemblées caractérisées par STM et XPS
No full textOne of the most important scientific challenges for the next decades is to build and tocontrol devices at the nanometer scale. These nano-devices promise to have many applications inphysics, chemistry and medicine. For example the nano-devices may be used to go further in theminiaturization of electronic compounds in order to improve the processors efficiency and perfor-mances. A judicious manner to create nano-devices is to take advantage of inter-molecular interac-tions in order to obtain self-assembled structures using a small numbers of molecules ("bottom-up"approach). The objective of this thesis was to create new organic self-assembled monolayers (SAMs),and to investigate their structures and electronic properties. Scanning tunneling microscopy (STM)was used to determine molecular organization with an atomic resolution. It was observed that themolecular skeleton and substituents used are key parameters driving the molecular self-assembly.Additionally we have showed that a post-annealing of the sample can be used not only to changethe structure of a perylene-based film as it is usually expected but also to modify its electronicstates. Photoemission-based techniques combined with synchrotron radiation facilities were usedto access to the chemical and electronic properties of SAMs. A strong modification of the line-shape and energy positions of the electronic states of SAMs with the molecular film thickness wasobserved. In the same way core-hole-clock spectroscopy shows that the charge transfer dynamicsat the PTCDI/Au(111) interface is strongly affected by the film thickness.L’un des défis scientifiques les plus importants pour les prochaines décennies est deconstruire des dispositifs à l’échelle nanométrique. Ces nano-dispositifs promettent d’avoir de nombreusesapplications en physique, chimie et médecine. Par exemple, ils peuvent être utilisés pouraller plus loin dans la miniaturisation des composés électroniques afin d’améliorer les performancesdes processeurs. Une manière judicieuse de créer des nano-dispositifs est de profiter des interactionsintermoléculaires afin d’obtenir des structures auto-assemblées à l’aide d’un petit nombre demolécules (approche "bottom-up"). L’objectif de cette thèse est de créer de nouvelles monocouchesauto-assemblées (SAMs), et d’examiner leurs structures et leurs propriétés électroniques. Toutd’abord, la microscopie à effet tunnel (STM) a été utilisée pour déterminer l’organisation moléculaireavec une résolution atomique. On a observé que le squelette moléculaire et les substituantsutilisés sont des paramètres clés pour contrôler l’auto-assemblage. En outre, nous avons montréqu’un post-recuit de l’échantillon peut être utilisé non seulement pour modifier la structure d’unfilm à base de pérylène comme généralement attendu, mais permet aussi de modifier ses étatsélectroniques. Par la suite, nous avons utilisé des techniques de photoémissions combinés avec desinstallations de rayonnement synchrotron pour accéder aux propriétés chimiques et électroniquesdes SAMs. Une forte modification de la forme et des positions en énergie des états électroniques desSAMs avec l’épaisseur du film moléculaire a été observée. De la même manière nous avons montréque la dynamique de transfert de charge à l’interface PTCDI/Au(111) est fortement affectée parl’épaisseur du film
A Multi Water Bag model of drift kinetic electron plasma
No full textÉquipe 107 : Physique des plasmas chaudsInternational audienceA Multi Water Bag model is proposed for describing drift kinetic plasmas in a magnetized cylindrical geometry, relevant for various experimental devices, solar wind modeling ... The Multi Water Bag (MWB) model is adapted to the description of a plasma with kinetic electrons as well as an arbitrary number of kinetic ions. This allows to describe the kinetic dynamics of the electrons, making possible the study of electron temperature gradient (ETG) modes, in addition to the effects of non adiabatic electrons on the ion temperature gradient (ITG) modes, that are of prime importance in the magnetized plasmas micro-turbulence [X. Garbet, Y. Idomura, L. Villard, T.H. Watanabe, Nucl. Fusion 50, 043002 (2010); J.A. Krommes, Ann. Rev. Fluid Mech. 44, 175 (2012)]. The MWB model is shown to link kinetic and fluid descriptions, depending on the number of bags considered. Linear stability of the ETG modes is presented and compared to the existing results regarding cylindrical ITG modes [P. Morel, E. Gravier, N. Besse, R. Klein, A. Ghizzo, P. Bertrand, W. Garbet, Ph. Ghendrih, V. Grandgirard, Y. Sarazin, Phys. Plasmas 14, 112109 (2007)]