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Distributed media cooperation for enhanced video communication

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第5期7卷 773-783页

作者： CHAKARESKI Jacob ecole polytechnique Fédérale de Lausanne

The author designed two algorithms for distributed cooperation among multiple video streams sharing common communication resources. The algorithms take advantage of an optimization framework that characterizes video packets such that joint resource allocation can be implemented not only over the packets of a single stream, but also across packets of different streams. The first algorithm enables collaboration among multiple video senders in an 802.11 CSMA/CA wireless network such that their joint performance is maximized. Via the algorithm, the users cooperatively establish transmission priorities based on the assigned characterizations of their video packets. The second technique allows for low-complexity joint bandwidth adaptation of multiple video streams at intermediate network nodes in the Internet in order to maximize the overall network performance. The author analyzes the advantages of the proposed algorithms over conventional solutions employed in such scenarios. It is shown that depending on system parameters such as available network data rate the proposed techniques can provide substantial gains in end-to-end performance.

关键词： Media cooperation, Distributed video streaming, Wireless networks, Resource allocation, Rate-quality optimization

Statistical physics in QCD evolution towards high energies

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Science China(Physics,Mechanics & Astronomy) 2015年第8期58卷 1-32页

作者： MUNIER Stphane Centre de physique thorique ′Ecole PolytechniqueCNRS Palaiseau France

The concepts and methods used for the study of disordered systems have proven useful in the analysis of the evolution equations of quantum chromodynamics in the high-energy regime: Indeed, parton branching in the semi-classical approximation relevant at high energies and at a fixed impact parameter is a peculiar branching-diffusion process, and parton branching supplemented by saturation effects(such as gluon recombination) is a reaction-diffusion process. In this review article, we first introduce the basic concepts in the context of simple toy models, we study the properties of the latter, and show how the results obtained for the simple models may be taken over to quantum chromodynamics.

关键词： quantum chromodynamics color dipole model color glass condensate stochastic fronts traveling waves reaction-diffusion

A FAST FREE MEMORY METHOD FOR AN EFFICIENT COMPUTATION OF CONVOLUTION KERNELS

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Journal of Computational Mathematics 2023年第6期41卷 1093-1116页

作者： Matthieu Aussal Marc Bakry ecole polytechnique(CMAP) INRIAInstitut Polytechnique ParisRoute de Saclay 91128PalaiseauFrance

We introduce the Fast Free Memory method(FFM),a new implementation of the Fast Multipole Method(FMM)for the evaluation of convolution *** FFM aims at being easier to implement while maintaining a high level of performance,capable of handling industrially-sized *** FFM avoids the implementation of a recursive tree and is a kernel independent *** give the algorithm and the relevant complexity *** quasi-linear complexity enables the evaluation of convolution products with up to one billion *** illustrate numerically the capacities of the FFM by solving Boundary Integral Equations problems featuring dozen of millions of *** implementation is made freely available under the GPL 3.0 license within the Gypsilab framework.

关键词： Convolution product Fast multipole method Boundary integral equations Open-source

Investigation of the short-term stress distribution in stopes and drifts backfilled with cemented paste backfill

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International Journal of Mining Science and Technology 2015年第5期25卷 721-728页

作者： Pengyu Yang Li Li department of Civil Geological and Mining EngineeringEcole Polytechnique de Montreal

Cemented paste backfill(CPB) is largely used in underground mines worldwide.A key issue associated with application of CPB is to estimate the stresses in backfilled stopes and on *** numerical and experimental results show that arching effect is absent shortly after the placement of CPB in ***,stress decreases in barricade drift with increasing distance between the measurement points and drawpoint have also been observed,demonstrating arching effect shortly after the pouring of *** explain these paradoxes,CPB is considered as Bingham fluid having a yield shear *** dimensional analytical solutions are proposed to evaluate the short-term total stresses in backfilled stopes and on barricades,accounting for the CPB's yield shear stress-induced arching *** diminution due to such arching effect in the backfilled stopes and on barricades is indeed *** the reduction becomes insignificant using typical yield shear stress and stope *** analyses indicate that the typical yield shear stress values do not fully correspond to field conditions where the yield shear stress would increase exponentially due to apparent consolidation(loss of water by drainage,a phenomenon similar to the desiccation of overly saturated fine-grained materials).

关键词： Mines Cemented paste backfill Yield shear stress Short-term total stresses Arching effect Analytical solutions

Engineering cancer vaccines using stimuli-responsive biomaterials

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Nano Research 2018年第10期11卷 5355-5371页

作者： Yu Zhao Yugang Guo Li Tang Institute of Bioengineering Ecole polytechnique federale de Lausanne (EPFL) Lausanne CH-1015 Switzerland Institute of Materials Science & Engineering Ecole polytechnique federale de Lausanne (EPFL) Lausanne CH- 1015 Switzerland

Cancer vaccines aimed at expanding the pool or increasing the activity of tumor-specific T cells against malignancies is an important immunotherapy modality that has been extensively pursued in the past decades. However, the clinical efficacy of cancer vaccines remains modest in comparison to other immunotherapies, such as checkpoint blockade and adoptive T cell therapy. this unsatisfactory performance is likely due to the suboptimal selection of tumor antigens for vaccine and inefficient delivery platform. Recently, vaccines designed to target cancer neoantigens have shown marked promise in both preclinical and early clinical studies. However, enormous challenges need to be overcome to develop a highly efficient and safe delivery strategy for targeting cancer vaccines to professional antigen-presenting cells and eliciting optimized immune response against cancers. To meet these challenges, biomaterials, particularly biomaterials that are designed to respond to certain environmental stimuli, termed as stimuli-responsive biomaterials, are being actively developed to precisely manipulate the trafficking and release of cancer vaccines in vivo for enhanced therapeutic efficacy and safety. In this mini review, we provide a brief overview of the recent advances in applying stimuli-responsive biomaterials in enhancing non-cellular cancer vaccines while focusing on the chemistry and material design with varied responsiveness. We also discuss the present challenges and opportunities in the field and provide a perspective for future directions.

关键词： cancer vaccine stimuli-responsive biomaterial nanoparticle immune response lymph node targeting cross-presentation

Effect of inoculum size and antibiotics on bacterial traveling bands in a thin microchannel defined by optical adhesive

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Microsystems & Nanoengineering 2021年第5期7卷 41-59页

作者： Yang Liu Thomas Lehnert Martin A.M.Gijs Laboratory of Microsystems Ecole Polytechnique Federale de LausanneCH-1015 LausanneSwitzerland

Phenotypic diversity in bacterial flagella-induced motility leads to complex collective swimming patterns,appearing as traveling bands with transient locally enhanced cell *** bands are known to be a bacterial chemotactic response to self-generated nutrient gradients during growth in resource-limited *** this work,we studied different parameters of Escherichia coli(***)collective migration,in particular the quantity of bacteria introduced initially in a microfluidic chip(inoculum size)and their exposure to antibiotics(ampicillin,ciprofloxacin,and gentamicin).We developed a hybrid polymer-glass chip with an intermediate optical adhesive layer featuring the microfluidic channel,enabling high-content imaging of the migration dynamics in a single bacterial layer,*** bacteria are confined in a quasi-2D space that is fully observable with a high-magnification microscope ***-chip bacterial motility and traveling band analysis was performed based on individual bacterial trajectories by means of custom-developed *** of swimming speed,tumble bias and effective diffusion properties allowed the assessment of phenotypic heterogeneity,resulting in variations in transient cell density distributions and swimming *** found that incubation of isogeneic£coli with different inoculum sizes eventually generated different swimming phenotype ***,incubation with antimicrobials promoted bacterial chemotaxis in specific cases,despite growth ***,*** filamentation in the presence of antibiotics was assessed,and the impact on motility was *** propose that the observation of traveling bands can be explored as an alternative for fast antimicrobial susceptibility testing.

关键词： traveling collective transient

High-fidelity optical diffraction tomography of multiple scattering samples

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Light(Science & Applications) 2019年第1期8卷 454-465页

作者： Joowon Lim Ahmed B.Ayoub Elizabeth E.Antoine demetri Psaltis ecole polytechnique Federale de Lausanne Optics LaboratoryCH-1015 LausanneSwitzerland

We propose an iterative reconstruction scheme for optical diffraction tomography that exploits the split-step nonparaxial(SSNP)method as the forward model in a learning tomography *** with the beam propagation method(BPM)previously used in learning tomography(LT-BPM),the improved accuracy of SSNP maximizes the information retrieved from measurements,relying less on prior assumptions about the sample.A rigorous evaluation of learning tomography based on SSNP(LT-SSNP)using both synthetic and experimental measurements confirms its superior performance compared with that of the *** from the accuracy of SSNP,LT-SSNP can clearly resolve structures that are highly distorted in the LT-BPM.A serious limitation for quantifying the reconstruction accuracy for biological samples is that the ground truth is *** overcome this limitation,we describe a novel method that allows us to compare the performances of different reconstruction schemes by using the discrete dipole approximation to generate synthetic ***,we explore the capacity of learning approaches to enable data compression by reducing the number of scanning angles,which is of particular interest in minimizing the measurement time.

关键词： scattering optical diffraction

Self-formation of hexagonal nanotemplates for growth of pyramidal quantum dots by metalorganic vapor phase epitaxy on patterned substrates

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Nano Research 2016年第11期9卷 3279-3290页

作者： Alessandro Surrente Romain Carron Pascal Gallo Alok Rudra Benjamin Dwir Eli Kapon Laboratory of Physics of Nanostructures Ecole Polytechnique Federale de Lausanne CH- 1015 Lausanne Switzerland

We demonstrate the self-formation of hexagonal nanotemplates on GaAs （111）B substrates patterned with arrays of inverted tetrahedral pyramids during metal-organic vapor phase epitaxy and its role in producing high-symmetry, site-controlled quantum dots （QDs）. By combining atomic force microscopy measurements on progressively thicker GaAs epitaxial layers with kinetic Monte Carlo growth simulations, we demonstrate self-maintained symmetry elevation of the QD formation sites from three-fold to six-fold symmetry. this symmetry elevation stems from adatom fluxes directed towards the high-curvature sites of the template, resulting in the formation of a fully three-dimensional hexagonal template after the deposition of relatively thin GaAs layers. We identified the growth conditions for consistently achieving a hexagonal pyramid bottom, which are useful for producing high-symmetry QDs for efficient generation of entangled photons.

关键词： metalorganic vapor phaseepitax kinetic Monte Carlosimulations epitaxial growth onpatterned substrates symmetry elevation adatom diffusion

Microfluidics-enabled phenotyping of a whole population of *** worms over their embryonic and post-embryonic development at single-organism resolution

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Microsystems & Nanoengineering 2018年第1期4卷 345-355页

作者： Maria Cristina Letizia Matteo Cornaglia Raphaël Trouillon Vincenzo Sorrentino Laurent Mouchiroud Maroun S.Bou Sleiman Johan Auwerx Martin A.M.Gijs ecole polytechnique Fédérale de Lausanne Laboratory of MicrosystemsLausanneSwitzerland ecole polytechnique Fédérale de Lausanne Laboratory of Integrative Systems PhysiologyLausanneSwitzerland

The organism Caenorhabditis elegans is a performant model system for studying human biological processes and diseases,but until now all phenome data are produced as population-averaged *** of individual responses to drug treatments would however be more ***,a new strategy to track different phenotypic traits of individual *** nematodes throughout their full life-cycle-i.e.,embryonic and post-embryonic development,until adulthood onset,differently from life-span-is *** an automated fashion,single worms were synchronized,isolated,and cultured from egg to adulthood in a microfluidic device,where their identity was preserved during their whole *** phenotypes were monitored and quantified for each animal,resulting in high-content phenome ***,the method was validated by analyzing the response of *** to doxycycline,an antibiotic fairly well-known to prolong the development and activate mitochondrial stress-response pathways in different ***,the obtained extensive single-worm phenome not only confirmed the dramatic doxycycline effect on the worm developmental delay,but more importantly revealed subtle yet severe treatment-dependent phenotypes that are representative of minority subgroups and would have otherwise stayed hidden in an averaged *** heterogeneous response started during the embryonic development,which makes essential having a dedicated chip that allows including this early developmental stage in the drug *** approach would therefore allow elucidating pharmaceutical or therapeutic responses that so far were still being overlooked.

关键词： fluid treatment otherwise