454 research outputs found
Analogies minus analogy test: measuring regularities in word embeddings
Vector space models of words have long been claimed to capture linguistic
regularities as simple vector translations, but problems have been raised with
this claim. We decompose and empirically analyze the classic arithmetic word
analogy test, to motivate two new metrics that address the issues with the
standard test, and which distinguish between class-wise offset concentration
(similar directions between pairs of words drawn from different broad classes,
such as France--London, China--Ottawa, ...) and pairing consistency (the
existence of a regular transformation between correctly-matched pairs such as
France:Paris::China:Beijing). We show that, while the standard analogy test is
flawed, several popular word embeddings do nevertheless encode linguistic
regularities
Small critical RNAs in the scrapie agent
Unconventional infectious agents cause transmissible spongiform encephalopathy (TSE) diseases including scrapie and bovine spongiform encephalopathy (BSE) in animals and Creutzfeldt-Jakob disease in humans. The protein only hypothesis claims that the TSE agent is composed solely of the protein called prion (PrP^sc^)^1^. This protein is the misfolded form of a host-encoded cellular protein, PrP^c^ exerting presumably a vital role at the synapse^2^. Even though now widely accepted, the prion concept fails to provide in certain circumstances^3-6^, a satisfying interpretation of the infectious phenomenon. Using the 263K scrapie-hamster model, we conducted a transmission study to search for a putative prion-associated factor indispensable for infectivity. Here we show that innocuous recombinant prion protein (recPrP) was capable, in a reproducible manner, of transmitting scrapie disease when the protein was [beta]–sheet converted in a solution containing PrP^sc^-derived RNA material. Analysis of the PrP-RNA mixture revealed the association of recPrP with two prominent populations of small RNA molecules having an average length of about ~27 and ~55 nucleotides. We conclude that the nature of the TSE agent seems to be composed of a nucleoprotein molecular complex, in which informative RNA molecules of small sizes are associated with the misfolded prion protein (PrP^sc^)
Integration of a human risk module into a risk management software
In the scientific literature and in practice, many questionnaires based on a myriad of measures have been designed and tested to measure and evaluate perceived work stress or employee involvement. The objective of our research is to identify the most significant elements of human risks and to combine them into a single score at the level of teams and departments. Indeed, for companies, what really matters are the stress or dissatisfaction factors that lead to harmful behavior that prevent managers and their teams from achieving their objectives. Based on this research, we are developing a module that will be incorporated into the Oxial software and will also be available as a stand-alone module. This module will collect and analyze the data to calculate a single score measuring the level of human risk. This aspect is very innovative, because no risk management software currently includes a module dedicated to human risks
Experimenting task-based runtimes on a legacy Computational Fluid Dynamics code with unstructured meshes
International audienceAdvances in high performance computing hardware systems lead to higher levels of parallelism and optimizations in scientific applications and more specifically in computational fluid dynamics codes. To reduce the level of complexity that such architectures bring while attaining an acceptable amount of the parallelism offered by modern clusters, the task-based approach has gained a lot of popularity recently as it is expected to deliver portability and performance with a relatively simple programming model. In this paper, we review and present the process of adapting part of Code Saturne, our legacy code at EDF R&D into a task-based form using the PARSEC (Parallel Runtime Scheduling and Execution Control) framework. We show first the adaptation of our prime algorithm to a simpler form to remove part of the complexity of our code and then present its task-based implementation. We compare performance of various forms of our code and discuss the perks of task-based runtimes in terms of scalability, ease of incremental deployment in a legacy CFD code, and maintainability
Experiments with multi-level parallelism runtimes on a CFD code with unstructured meshes
International audienceLarge applications for parallel computers and more specifically unstructured Computational Fluid Dynamics codes are often based on the bulk synchronous parallelism approach (BSP model) and therefore mostly exploit parallelism using runtime systems like the Message Passing Interface (MPI) which has enabled strong, relatively portable and quite durable performances for these codes for many years. However, as MPI was developed for distributed computing, we do not expect its standalone use to be the best fit for recent many-core architectures. Indeed, the ever growing performance of high performance machines we are witnessing comes mostly through the aggregation of different computing devices in order to build heterogeneous machines. Those are the combination of traditional computing units (CPUs) with accelerators, namely many-core architectures such as GPGPUs or Intel Xeon-Phi accelerators. This hybridiza-tion of HPC clusters requires current scientific code developers to master more and more techniques and programming models in order to harness the quintessence of their machines. As the post-petascale era has long been foreseen, runtime systems developers have been investigating other parallelism paradigms. Notably, the task based approach has gained a lot of popularity recently as it is expected to deliver portability and performance with a relatively simple programming model. Tasks can be both local or distant, so a single model can handle both inter-node and intra-node aspects. In addition, computation-communication overlap is straightforward. Opposed to the Coarse Grain Parallelism, performance depends strongly on choosing a good data grain size for each task, which should require performance measuring and tuning but no additional programming effort. As Code_Saturne [1], our CFD code at EDF R&D is based on unstructured meshes, with a significant part of its code being memory-bound, refined parallelism through the use of MPI + X solutions such as MPI + OpenMP often fails to deliver significant (or any) performance improvements , though it does reduce the memory consumption per thread. Using a simple "loop-local" OpenMP model, as we increase the number of threads per MPI rank, performance drops rapidly, since many secondary loops are not threaded; and avoiding data races often requires specific re-numbering strategies, which may not be easily adapted everywhere with a reasonable programming effort. These diminishing returns tend to limit the efforts which are worthwhile to spend in addition to the base MPI model. We may see HPC current technologies evolution as unfavorable to an unstructured CFD code like Code_Saturne in its current form. This is why we decided to investigate recent HPC techniques and runtime systems for a sustainable, easy to propagate, portable and efficient solution to bring better performance and adaptability to Code_Saturne. As many teams are already dedicating their work to propose new solvers and solve dense linear algebra, we decided to focus on another part of the puzzle, namely our gradient reconstruction computation. As a significant portion of our main current numerical schemes, it has a high impact over the performance of our code and an intermediate computational intensity. As such, we propose in this article a review of different implementations of our gradient computation towards the implementation of a task based approach through the use of task-based HPC runtime systems, and more specifically the PaRSEC [2] framework. The Parallel Runtime Scheduling and Execution Control (PaRSEC) framework implements a task-based dataflow-driven programming model aimed at offering high performance while relieving developers of supercomputers' hardware complexity. We show that our first implementation offers comparable performance while increasing the arithmetic intensity of its computation (see figure 1). Moreover, by removing some data dependencies , our cell based approach paves the way for a more refined grain parallelism approach. We then push this approach to our prime objective – task based approaches – and implement our gradient computation using the PaRSEC runtime. Finally, we propose some insights on the use of
Analogies minus analogy test: measuring regularities in word embeddings
International audienceVector space models of words have long been claimed to capture linguistic regularities as simple vector translations, but problems have been raised with this claim. We decompose and empirically analyze the classic arithmetic word analogy test, to motivate two new metrics that address the issues with the standard test, and which distinguish between class-wise offset concentration (similar directions between pairs of words drawn from different broad classes, such as France-London, China-Ottawa,. . .) and pairing consistency (the existence of a regular transformation between correctly-matched pairs such as France:Paris::China:Beijing). We show that, while the standard analogy test is flawed, several popular word embeddings do nevertheless encode linguistic regularities
Apport des lignes à ondes lentes S-CPW aux performances d'un front-end millimétrique en technologie CMOS avancée
L objectif de ce travail est de concevoir et de caractériser un front-end millimétriqueutilisant des lignes de propagation à ondes lentes S-CPW optimisées en technologies CMOS avancées.Ces lignes présentant des facteurs de qualité 2 à 3 fois supérieurs à ceux des lignes classiques de typemicroruban ou CPW.Dans le premier chapitre, l impact de l évolution des noeuds technologiques CMOS sur lesperformances des transistors MOS aux fréquences millimétriques et sur les lignes de propagation ainsiqu un état de l art concernant les performances des front-end sont présentés. Le deuxième chapitreconcerne la réalisation des lignes S-CPW dans différentes technologies CMOS et la validation d unmodèle phénoménologique électrique équivalent. Le troisième chapitre est dédié à la conceptiond amplificateurs de puissance à 60 GHz utilisant ces lignes S-CPW en technologies CMOS 45 et65 nm. Cette étude a permis de mettre en évidence l apport des lignes à ondes lentes aux performancesdes amplificateurs de puissance fonctionnant dans la gamme des fréquences millimétriques. Uneméthode de conception basée sur les règles d électro-migration et permettant une optimisation desperformances a été développée. Finalement, un amplificateur faible bruit et un commutateur d antennetravaillant à 60 GHz et à base de lignes S-CPW ont été conçus en technologie CMOS 65 nm afin degénéraliser l impact de ce type de lignes sur les performances des front-end millimétriques.The objective of this work is to design and characterize a millimeter-wave front-end usingthe optimized slow-wave transmission lines S-CPW in advanced CMOS technologies. The qualityfactor of these transmission lines is twice to three times higher than that of the conventionaltransmission lines such as microstrip lines and coplanar waveguides.In the first chapter, the influence of CMOS scaling-down on the performance of transistors atmillimeter-wave frequencies and on the transmission lines was studied. In addition, a state of the artwith regard to the performance of the front-end was presented. The second chapter concerns about therealization of the S-CPW lines in different CMOS technologies and the validation of an electricalequivalent model. The third chapter is dedicated to the design of 60-GHz power amplifiers using theseS-CPW lines in CMOS 45 and 65 nm technologies. This study highlighted the performanceenhancement of power amplifiers operating at millimeter-wave frequencies by using the slow-wavetransmission lines. A design method based on the electro-migration rules was also developed. Finally,a low noise amplifier and an antenna switch operating at 60 GHz were designed in CMOS 65 nm inorder to generalize the impact of such transmission lines on the performance of the millimeter-wavefront-end.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF
Revisiting the global patterns of seasonal cycle in sea surface salinity
Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 126(4), (2021): e2020JC016789, https://doi.org/10.1029/2020JC016789.Argo profiling floats and L-band passive microwave remote sensing have significantly improved the global sampling of sea surface salinity (SSS) in the past 15 years, allowing the study of the range of SSS seasonal variability using concurrent satellite and in situ platforms. Here, harmonic analysis was applied to four 0.25° satellite products and two 1° in situ products between 2016 and 2018 to determine seasonal harmonic patterns. The 0.25° World Ocean Atlas (WOA) version 2018 was referenced to help assess the harmonic patterns from a long-term perspective based on the 3-year period. The results show that annual harmonic is the most characteristic signal of the seasonal cycle, and semiannual harmonic is important in regions influenced by monsoon and major rivers. The percentage of the observed variance that can be explained by harmonic modes varies with products, with values ranging between 50% and 72% for annual harmonic and between 15% and 19% for semiannual harmonic. The large spread in the explained variance by the annual harmonic reflects the large disparity in nonseasonal variance (or noise) in the different products. Satellite products are capable of capturing sharp SSS features on meso- and frontal scales and the patterns agree well with the WOA 2018. These products are, however, subject to the impacts of radiometric noises and are algorithm dependent. The coarser-resolution in situ products may underrepresent the full range of high-frequency small scale SSS variability when data record is short, which may have enlarged the explained SSS variance by the annual harmonic.L. Yu was funded by NASA Ocean Salinity Science Team (OSST) activities through Grant 80NSSC18K1335. FMB was funded by the NASA OSST through Grant 80NSSC18K1322. E. P. Dinnat was funded by NASA through Grant 80NSSC18K1443. This research is carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA.2021-09-1
Regulation by protein kinase-C of putative P-type Ca channels expressed in Xenopus oocytes from cerebellar mRNA
AbstractXenopus oocytes injected with rat cerebellar mRNA expressed functional voltage-dependent Ca channels detected as an inward Ba current (IBa). The pharmacological resistance to dihydropyridines and ω-conotoxin together with the blockade obtained with Agelenopsis aperta venom suggest that these channels could be somehow assimilated to P-type Ca channels. The precise nature of the transplanted Ca channels was assessed by hybrid-arrest experiments using a specific oligonucleotide antisense-derivated from the recently cloned α1-subunit of P channels (BI-1 clone). In addition, we demonstrate that exogenous Ca channel activity was enhanced by two different PKC activators (a phorbol ester and a structural analog to diacylglycerol). The general electrophysiological and pharmacological properties of the stimulated Ca channels remain unchanged. This potentiation induced by PKC activators is antagonized by a PKC inhibitor (staurosporine) and by a monoclonal antibody directed against PKC. It is concluded that P-type Ca channels are potentially regulated by PKC phosphorylation and the functional relevance of this intracellular pathway is discussed
Electrical conductivity and Raman imaging of double wall carbon nanotubes in a polymer matrix
Raman spectroscopy is used to access the dispersion state of DWNTs in a PEEK polymer matrix. The interaction of the outer tube with the matrix can be determined from the line shape of the Raman G band. This allows us to distinguish regions where the nanotubes are well dispersed and regions where the nanotubes are agglomerated. The percolation threshold of the electrical conductivity of the double wall carbon nanotubes (DWNTs)/PEEK nanocomposites is found to be at 0.2–0.3 wt.%. We find a maximum electrical conductivity of 3 x 10-2 S/cm at 2 wt.% loading. We detect nanotube weight concentrations as low as 0.16 wt.% by Raman spectroscopy using a yellow excitation wavelength. We compare the Raman images with transmission electron microscopy images and electrical conductivity measurements. A statistical method is used to find a quantitative measure of the DWNTs dispersion in the polymer matrix from the Raman images
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