1,225 research outputs found
Adaptive Speckle Imaging Interferometry: a new technique for the analysis of microstructure dynamics, drying processes and coating formation
We describe an extension of multi-speckle diffusing wave spectroscopy adapted
to follow the non-stationary microscopic dynamics in drying films and coatings
in a very reactive way and with a high dynamic range. We call this technique
"Adaptive Speckle Imaging Interferometry". We introduce an efficient tool, the
inter-image distance, to evaluate the speckle dynamics, and the concept of
"speckle rate" (SR, in Hz) to quantify this dynamics. The adaptive algorithm
plots a simple kinetics, the time evolution of the SR, providing a non-invasive
characterization of drying phenomena. A new commercial instrument, called
HORUS(R), based on ASII and specialized in the analysis of film formation and
drying processes is presented.Comment: 11 pages, 4 figure
Charged particle jet measurements with the ALICE experiment in proton-proton collisions at the LHC
We present preliminary results of measurements of charged particle jet
properties in proton-proton collisions at = 7 TeV using the ALICE
detector. Jets are reconstructed using and SISCone jet
finding algorithms with resolution parameter in the range of transverse
momentum from 20 to 100 GeV/ in the midrapidity region
(\mid\eta\mid\textless 0.5). The uncorrected charged jet spectra obtained
using the three different jet finders show good agreement. The data are
compared to predictions from PYTHIA-Perugia0, PYTHIA-Perugia2011, and PHOJET.
The mean charged particle multiplicity in leading jets increases with
increasing jet and is consistent with model predictions. The radial
distributions of transverse momentum about the jet direction and the
distributions of the average radius containing 80% of the total jet
found in the jet cone ( in this analysis), indicate that high jets are more collimated than low jets.Comment: 6 pages, 6 figures, Conference Proceedings submitted for the 28th
Winter Workshop on Nuclear Dynamics, Puerto Rico, April 7-14, 201
Film formation analysis by diffusive wave spectroscopy
The thin layer analysis is very important for several sectors of industry. Indeed, environmental laws and improvement of performances lead the manufacturers to innovate in the field of coatings and paints. Several classical techniques of characterization (TGA, DMA, etc.) used with this intention do not allow to perform the analysis in situ and are often long and tedious to set up. We propose to solve this problem with a newoptical process. Its technology based on multi-speckle diffusivewave spectroscopy (MS-DWS) allows making real-time analysis in a non-destructive way thanks to an optical measurement. The aim of this work is to highlight correlations between this new technology and the classical methods of analysis. Two film forming polymeric materials were studied, a polydimethylsiloxane (PDMS) and a commercial paint based on an aqueous dispersion of acrylic copolymers. The PDMSwas chosen for the simplicity of its film forming process and is used as model. The paint having a more complex drying mechanism enables to complete this study
Si and Mn Abundances in Damped Lya Systems with Low Dust Content
We have measured the abundances of Zn, Si, Mn, Cr, Fe, and Ni in three damped
Lyman alpha systems at redshifts z < 1 from high resolution echelle spectra of
QSOs recorded with the Keck I telescope. In all three cases the abundances of
Cr, Fe, and Ni relative to Zn indicate low levels of dust depletions. We
propose that when the proportion of refractory elements locked up in dust
grains is less than about 50 percent, it is plausible to assume an
approximately uniform level of depletion for all grain constituents and, by
applying a small dust correction, recover the intrisic abundances of Si and Mn.
We use this approach on a small sample of damped systems for which it is
appropriate, with the aim of comparing the metallicity dependence of the ratios
[Si/Fe] and [Mn/Fe] with analogous measurements in Milky Way stars. The main
conclusion is that the relative abundances of both elements in distant galaxies
are broadly in line with expectations based on Galactic data. Si displays a
mild enhancement at low metallicities, as expected for an alpha-capture
element, but there are also examples of near-solar [Si/Fe] at [Fe/H] < -1. The
underabundance of Mn at low metallicities is possibly even more pronounced than
that in metal-poor stars, and no absorption system has yet been found where
[Mn/Fe] is solar. The heterogeneous chemical properties of damped Lyman alpha
systems, evident even from this limited set of measurements, provide further
support for the conclusion from imaging studies that a varied population of
galaxies gives rise to this class of QSO absorbers.Comment: 29 pages, LaTex, 7 Postscript Figures. Accepted for Publication in
the Astrophysical Journa
An Imaging and Spectroscopic Study of the z=3.38639 Damped Lyman Alpha System in Q0201+1120: Clues to Star Formation Rate at High Redshift
We present the results of a series of imaging and spectroscopic observations
aimed at identifying and studying the galaxy responsible for the z = 3.38639
damped lya system in the z = 3.61 QSO Q0201+1120. We find that the DLA is part
of a concentration of matter which includes at least four galaxies (probably
many more) over linear comoving dimensions, greater than 5h^-1Mpc. The absorber
may be a 0.7 L* galaxy at an impact parameter of 15 h^-1 kpc, but follow-up
spectroscopy is still required for positive identification. The gas is
turbulent, with many absorption components distributed over approximately 270
km/s and a large spin temperature, T_s greater than 4000K. The metallicity is
relatively high for this redshift, Z(DLA) approximately 1/20 Z(solar). From
consideration of the relative ratios of elements which have different
nucleosynthetic timescales, it would appear that the last major episode of star
formation in this DLA occurred at z greater than 4.3, more than approximately
500 Myr prior to the time when we observe it.Comment: Accepted for publication in Ap
Mogador - Modélisation de l’atelier d’engraissement porcin pour prédire ses résultats économiques et ses impacts environnementaux
To meet economic and environmental challenges of pig production, farmers need tools to assess the impact of their facilities, identify possible improvements and be guided in their technical and economic management. A model of the pig fattening unit has been developed for this purpose as part of the MOGADOR project. Based on the characteristics of the structure and the main farming practices, the model produces the technical and economic results and its environmental impacts by Life Cycle Assessment approach. The originality and the performance of the model reside in the fact that it takes into account the variability of the individual performances of the pigs, in interaction with the practices of the breeding (driving, feeding) and its structure (rooms of fattening). The model was evaluated according to three main stages: expertise, sensitivity analysis and comparison of predicted results toobserved results. The predictive quality of the model and the calibration procedure make it possible to consider using the model for research and advisory services. A first decision support tool is available on Internet to consult a library of simulations performed with the model. The analyzes can then be completed by using the expert model.Pour répondre aux enjeux économiques et environnementaux de la production porcine, les éleveurs ont besoin d’outils pour apprécier l’impact de leur atelier, identifier les pistes d’amélioration et être guidés dans leur pilotage technico-économique. Un modèle de l’atelier d’engraissement a été développé en ce sens dans le cadre du projet MOGADOR. À partir des caractéristiques de la structure de l’atelier et des principales pratiques d’élevage, le modèle produit les résultats techniques et économiques de l’atelier et ses impacts environnementaux par Analyse du Cycle de Vie. L’originalité et la performance du modèle résident dans le fait qu’il prend en compte la variabilité des performances individuelles des porcs, en interaction avec les pratiques de l’élevage (conduite, alimentation) et sa structure (salles d’engraissement). Le modèle a été évalué suivant trois grandes étapes : par expertise, par analyse de sensibilité et par comparaison de résultats prédits à des résultats observés. La qualité de prédiction dumodèle et la procédure d’étalonnage établie permettent d’envisager une utilisation du modèle pour la recherche et pour le conseil en élevage. Un premier outil d’aide à la décision est disponible sur Internet pour consulter une bibliothèque de simulations réalisées à l’aide du modèle. Les analyses peuvent ensuite être complétées par l’utilisation du modèle expert
Effective Rheology of Bubbles Moving in a Capillary Tube
We calculate the average volumetric flux versus pressure drop of bubbles
moving in a single capillary tube with varying diameter, finding a square-root
relation from mapping the flow equations onto that of a driven overdamped
pendulum. The calculation is based on a derivation of the equation of motion of
a bubble train from considering the capillary forces and the entropy production
associated with the viscous flow. We also calculate the configurational
probability of the positions of the bubbles.Comment: 4 pages, 1 figur
The coming of the Greeks to Provence and Corsica: Y-chromosome models of archaic Greek colonization of the western Mediterranean
<p>Abstract</p> <p>Background</p> <p>The process of Greek colonization of the central and western Mediterranean during the Archaic and Classical Eras has been understudied from the perspective of population genetics. To investigate the Y chromosomal demography of Greek colonization in the western Mediterranean, Y-chromosome data consisting of 29 YSNPs and 37 YSTRs were compared from 51 subjects from Provence, 58 subjects from Smyrna and 31 subjects whose paternal ancestry derives from Asia Minor Phokaia, the ancestral embarkation port to the 6<sup>th </sup>century BCE Greek colonies of Massalia (Marseilles) and Alalie (Aleria, Corsica).</p> <p>Results</p> <p>19% of the Phokaian and 12% of the Smyrnian representatives were derived for haplogroup E-V13, characteristic of the Greek and Balkan mainland, while 4% of the Provencal, 4.6% of East Corsican and 1.6% of West Corsican samples were derived for E-V13. An admixture analysis estimated that 17% of the Y-chromosomes of Provence may be attributed to Greek colonization. Using the following putative Neolithic Anatolian lineages: J2a-DYS445 = 6, G2a-M406 and J2a1b1-M92, the data predict a 0% Neolithic contribution to Provence from Anatolia. Estimates of colonial Greek vs. indigenous Celto-Ligurian demography predict a maximum of a 10% Greek contribution, suggesting a Greek male elite-dominant input into the Iron Age Provence population.</p> <p>Conclusions</p> <p>Given the origin of viniculture in Provence is ascribed to Massalia, these results suggest that E-V13 may trace the demographic and socio-cultural impact of Greek colonization in Mediterranean Europe, a contribution that appears to be considerably larger than that of a Neolithic pioneer colonization.</p
Open science discovery of potent noncovalent SARS-CoV-2 main protease inhibitors
INTRODUCTION
COVID-19 became a global pandemic partially as a result of the lack of easily deployable, broad-spectrum oral antivirals, which complicated its containment. Even endemically, and with effective vaccinations, it will continue to cause acute disease, death, and long-term sequelae globally unless there are accessible treatments. COVID-19 is not an isolated event but instead is the latest example of a viral pandemic threat to human health. Therefore, antiviral discovery and development should be a key pillar of pandemic preparedness efforts.
RATIONALE
One route to accelerate antiviral drug discovery is the establishment of open knowledge bases, the development of effective technology infrastructures, and the discovery of multiple potent antivirals suitable as starting points for the development of therapeutics. In this work, we report the results of the COVID Moonshot—a fully open science, crowdsourced, and structure-enabled drug discovery campaign—against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro). This collaboration may serve as a roadmap for the potential development of future antivirals.
RESULTS
On the basis of the results of a crystallographic fragment screen, we crowdsourced design ideas to progress from fragment to lead compounds. The crowdsourcing strategy yielded several key compounds along the optimization trajectory, including the starting compound of what became the primary lead series. Three additional chemically distinct lead series were also explored, spanning a diversity of chemotypes.
The collaborative and highly automated nature of the COVID Moonshot Consortium resulted in >18,000 compound designs, >2400 synthesized compounds, >490 ligand-bound x-ray structures, >22,000 alchemical free-energy calculations, and >10,000 biochemical measurements—all of which were made publicly available in real time. The recently approved antiviral ensitrelvir was identified in part based on crystallographic data from the COVID Moonshot Consortium.
This campaign led to the discovery of a potent [median inhibitory concentration (IC50) = 37 ± 2 nM] and differentiated (noncovalent and nonpeptidic) lead compound that also exhibited potent cellular activity, with a median effective concentration (EC50) of 64 nM in A549-ACE2-TMPRSS2 cells and 126 nM in HeLa-ACE2 cells without measurable cytotoxicity. Although the pharmacokinetics of the reported compound is not yet optimal for therapeutic development, it is a promising starting point for further antiviral discovery and development.
CONCLUSION
The success of the COVID Moonshot project in producing potent antivirals, building open knowledge bases, accelerating external discovery efforts, and functioning as a useful information-exchange hub is an example of the potential effectiveness of open science antiviral discovery programs. The open science, patent-free nature of the project enabled a large number of collaborators to provide in-kind support, including synthesis, assays, and in vitro and in vivo experiments. By making all data immediately available and ensuring that all compounds are purchasable from Enamine without the need for materials transfer agreements, we aim to accelerate research globally along parallel tracks. In the process, we generated a detailed map of the structural plasticity of Mpro, extensive structure-activity relationships for multiple chemotypes, and a wealth of biochemical activity data to spur further research into antivirals and discovery methodologies. We hope that this can serve as an alternative model for antiviral discovery and future pandemic preparedness.
Further, the project also showcases the role of machine learning, computational chemistry, and high-throughput structural biology as force multipliers in drug design. Artificial intelligence and machine learning algorithms help accelerate chemical synthesis while balancing multiple competing molecular properties. The design-make-test-analyze cycle was accelerated by these algorithms combined with planetary-scale biomolecular simulations of protein-ligand interactions and rapid structure determination
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