Artykuły w czasopismach na temat „Observations au sol (météorologie)”
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1
Cantat, Olivier, Olivier Planchon, Hervé Quénol, Edwige Savouret, Benjamin Bois, François Beauvais i Sophie Brunel-Muguet. "Gelées tardives et viticulture en basse et moyenne Vallée de la Loire (France)". Climatologie 16 (2019): 91–128. http://dx.doi.org/10.4267/climatologie.1413.
Streszczenie:
Dès que la situation météorologique est propice à l’établissement d’un temps clair et calme, des contrastes thermiques importants apparaissent de nuit au gré de facteurs locaux comme la topographie et la nature des sols. Si l’on croise ces composantes atmosphériques et géographiques avec la phénologie de la vigne, le printemps s’avère être une période particulièrement surveillée en raison de l’occurrence possible de gelées pouvant hypothéquer le développement du végétal et, par conséquent, pénaliser la production de raisins impactant les filières maraîchères et viticoles. Ce fut notamment le cas en France et dans certains pays voisins fin avril 2016, avec localement des gelées sous abri fortes (inférieures à -5°C) et durables (plusieurs heures consécutives). Le phénomène s’est également produit en 2017 et 2019. Pour illustrer les combinaisons de situations météorologiques et de phénomènes topoclimatiques à risques gélifs chez la vigne, l’étude de cas porte sur la basse et moyenne vallée de la Loire, région viticole française objet du programme européen LIFE-ADVICLIM (ADaptation of VIticulture to CLIMate change : High resolution observations of adaptation scenarii). Après avoir présenté le cadre climatique général du secteur d’étude, le contexte météorologique d’échelle synoptique et la particularité des gelées tardives par rapport à celles de pleine saison hivernale, l’article analyse la géographie à échelle fine de l’événement gélif du 27 avril 2016 entre Nantes et Orléans. Un zoom sur deux stations voisines représentatives de contextes géographiques différents (Romorantin à la topographie en creux sur sol sableux et Lye sur une colline dégagée) permet ensuite de montrer comment les jeux d’échelles spatio-temporelles mènent à une répartition thermique tout en contrastes, entre l’échelle synoptique (pour définir un potentiel de gelée tardive) et locale (pour en voir l’expression effective sur le terrain, en intensité comme en durée).
2
Planton, Serge, i Jean-François Mahfouf. "Une nouvelle description des surfaces continentales pour les modèles de Météo-France : les origines du schéma Isba". La Météorologie, nr 108 (2020): 038. http://dx.doi.org/10.37053/lameteorologie-2020-0014.
Streszczenie:
Le schéma de surface Isba a été conçu pour représenter aussi simplement que possible des processus complexes d'interactions entre le sol, la végétation et l'atmosphère. Les choix méthodologiques adoptés pour sa construction ont été guidés par son implémentation future dans des modèles atmosphériques de moyenne échelle, de prévision météorologique et de climat. Son développement initial a été grandement facilité par la disponibilité des données d'observation de la campagne Hapex-Mobilhy, permettant de valider les choix méthodologiques et d'ajuster certains des paramètres du schéma. Cette approche de développement s'appuyant sur les données de campagnes de mesures ne s'est pas démentie par la suite. The Isba surface scheme was designed to represent as simply as possible complex interaction process between the soil, the vegetation and the atmosphere. The methodological choices adopted to construct it were guided by its future implementation in mesoscale, weather and climate models. Its initial development was greatly facilitated by the availability of observational data from the Hapex-Mobilhy field, enabling the methodological choices to be validated and some parameters of the scheme to be adjusted. This development approach, based on field campaign data, was maintained later.
3
Olivier, Chomette, Raymond Armante, Cyril Crevoisier, Thibault Delahaye, Dimitri Edouart, Fabien Gibert, Frédéric Nahan i Yoann Tellier. "CH4 IPDA Lidar mission data simulator and processor for MERLIN: prototype development at LMD/CNRS/Ecole Polytechnique". EPJ Web of Conferences 176 (2018): 02016. http://dx.doi.org/10.1051/epjconf/201817602016.
Streszczenie:
The MEthane Remote sensing Lidar missioN (MERLIN), currently in phase C, is a joint cooperation between France and Germany on the development of a spatial Integrated Path Differential Absorption (IPDA) LIDAR (LIght Detecting And Ranging) to conduct global observations of atmospheric methane. This presentation will focus on the status of a LIDAR mission data simulator and processor developed at LMD (Laboratoire de Météorologie Dynamique), Ecole Polytechnique, France, for MERLIN to assess the performances in realistic observational situations.
4
Joussaume, Sylvie. "Simulation of Airborne Impurity Cycles Using Atmospheric General Circulation Models". Annals of Glaciology 7 (1985): 131–37. http://dx.doi.org/10.3189/s0260305500006042.
Streszczenie:
Atmospheric general circulation models are believed to be appropriate tools for studying airborne impurity cycles in order to supplement observations and to improve our knowledge of gaseous and particulate pollutant cycles in the atmosphere. The main aspects of the modelling of tracer cycles are reviewed and illustrated by two particular examples: desert dust particles in the 1 μm range and water isotope species HDO and H218O. Some results from a first simulation including desert dust and water isotope cycles using the model developed at the Laboratoire de Météorologie Dynamique (LMD) are presented and compared to observations, with particular emphasis on ice-sheet data. The relatively good agreement with observations obtained so far is encouraging and should stimulate further applications to other types of tracers.
5
Joussaume, Sylvie. "Simulation of Airborne Impurity Cycles Using Atmospheric General Circulation Models". Annals of Glaciology 7 (1985): 131–37. http://dx.doi.org/10.1017/s0260305500006042.
Streszczenie:
Atmospheric general circulation models are believed to be appropriate tools for studying airborne impurity cycles in order to supplement observations and to improve our knowledge of gaseous and particulate pollutant cycles in the atmosphere. The main aspects of the modelling of tracer cycles are reviewed and illustrated by two particular examples: desert dust particles in the 1 μm range and water isotope species HDO and H2 18O. Some results from a first simulation including desert dust and water isotope cycles using the model developed at the Laboratoire de Météorologie Dynamique (LMD) are presented and compared to observations, with particular emphasis on ice-sheet data. The relatively good agreement with observations obtained so far is encouraging and should stimulate further applications to other types of tracers.
6
Boussafir, Yasmina, Dimitri Mercadier, Lucile Saussaye, Julien Bisson, Sébastien Patouillard, Anthony Matynia, Christian Brulé i Franck Guirado. "Instrumentation de la digue de La Riche : première étape vers un observatoire des interactions sols–climat". Revue Française de Géotechnique, nr 178 (2024): 5. http://dx.doi.org/10.1051/geotech/2024008.
Streszczenie:
Le changement climatique a des effets perceptibles sur notre environnement immédiat, que ce soit sur la modification de la météorologie, le niveau d’eau dans les rivières, l’intensité des aléas « inondations », la sévérité des étiages ou les niveaux de nappes phréatiques. Les effets indirects pouvant impacter les ouvrages hydrauliques sont malheureusement rarement quantifiés mais commencent à être documentés. Certains gestionnaires commencent également à se préoccuper de ces effets et souhaitent s’en prémunir. La recherche de nouveaux indicateurs de performance des ouvrages en lien avec les effets du changement climatique nécessite de disposer de données quantitatives. L’article présentera l’observatoire des interactions sols–climat mis en place sur la digue de La Riche grâce au partenariat entre la Dreal Centre–Val-de-Loire, Tours Métropole–Val-de-Loire, la Direction départementale des territoires d’Indre-et-Loire, le Cerema et l’université Gustave Eiffel. Les capteurs mis en place en mars 2023 à l’occasion des travaux d’épaississement de la digue de La Riche permettront d’acquérir des données couplées de sol et de météorologie. Le jeu de capteurs prévu pour le suivi comprend des sondes tensiométriques, des sondes de mesure de teneur en eau volumique et de température, une station météorologique, des piézomètres et une caméra. L’interprétation de ces données devrait enrichir notre compréhension des phénomènes et permettre de développer une doctrine concernant l’adaptation des ouvrages en terre de protection contre les inondations au changement climatique. L’article présente le détail de l’instrumentation mise en œuvre et les objectifs recherchés.
7
Kerr, Yann, Philippe Waldteufel, Jean-Pierre Wigneron, Jacqueline Boutin, Nicolas Reul, Ahmad Al Bitar, Delphine Leroux, Arnaud Mialon, Philippe Richaume i Susanne Mecklenburg. "The Soil Moisture and Ocean Salinity (SMOS) Mission: first results and achievements". Revue Française de Photogrammétrie et de Télédétection, nr 200 (19.04.2014): 12–19. http://dx.doi.org/10.52638/rfpt.2012.57.
Streszczenie:
La mission SMOS (Soil moisture and Ocean Salinity) a été lancée avec succès le 2 novembre 2009. Cette mission menée par l'ESA (Agence Spatiale Europénne) est dédiée à la mesure de l'humidité superficielle des sols sur les continents (avec une précision recherchée de 0,04m3/m3) et la salinité des océans (objectif 0.1psu). Ces deux quantités géophysiques sont très importantes car elle contrôle le budget énergétique à l'interface sol-atmosphère. Leur connaissance à l'échelle globale est utile pour les recherches sur le climat et la météorologie, en particulier pour les modèles de prévision numérique. Elles ont aussi un très grand potentiel un très grand nombre d'application, comme par exemple pour le suivi des ouragans ou la gestion des ressources en eau. Les six premiers mois ont été dédiés à la recette en vol qui a permis de vérifier le satellite le segment sol et l'étalonnage. Cette phase s'est achevée avec succès en mai 2010 et SMOS fonctionne de façon opérationnelle depuis, fournissant de données à la communauté internationale. Les performances de l'instrument sont globalement conformes aux spécifications. Cependant, les interférences radio sont présentes au-dessus de l'Europe, du Moyen-Orient et de l'Asie. Cesémissions parasites dans la bande protégée perturbent la mesure de façon significative. La génération des produits de niveau 2 et 3 est une activité en cours avec des améliorations régulières de sorties.
8
Coindreau, O., F. Hourdin, M. Haeffelin, A. Mathieu i C. Rio. "Assessment of Physical Parameterizations Using a Global Climate Model with Stretchable Grid and Nudging". Monthly Weather Review 135, nr 4 (1.04.2007): 1474–89. http://dx.doi.org/10.1175/mwr3338.1.
Streszczenie:
Abstract The Laboratoire de Météorologie Dynamique atmospheric general circulation model with zooming capability (LMDZ) has been used in a nudged mode to enable comparison of model outputs with routine observations and evaluate the model physical parameterizations. Simulations have been conducted with a stretched grid refined over the vicinity of Paris, France, where observations, collected at the Trappes station (Météo-France) and at the Site Instrumental de Recherche par Télédétection Atmosphérique observatory, are available. For the purpose of evaluation of physical parameterizations, the large-scale component of the modeled circulation is adjusted toward ECMWF analyses outside the zoomed area only, whereas the inside region can evolve freely. A series of sensitivity experiments have been performed with different parameterizations of land surface and boundary layer processes. Compared with previous versions of the LMDZ model, a “thermal plume model,” in association with a constant resistance to evaporation improves agreement with observations. The new parameterization significantly improves the representation of seasonal and diurnal cycles of near-surface meteorology, the day-to-day variability of planetary boundary layer height, and the cloud radiative forcing. This study emphasizes the potential of using a climate model with a nudging and zooming capability to assess model physical parameterizations.
9
Verma, S., O. Boucher, M. S. Reddy, S. K. Deb, H. C. Upadhyaya, P. Le Van, F. S. Binkowski i O. P. Sharma. "Tropospheric distribution of sulphate aerosol mass and number concentration during INDOEX-IFP and its transport over the Indian Ocean: a GCM study". Atmospheric Chemistry and Physics Discussions 5, nr 1 (31.01.2005): 395–436. http://dx.doi.org/10.5194/acpd-5-395-2005.
Streszczenie:
Abstract. An interactive sulphate aerosol chemistry module has been incorporated in the Laboratoire de Météorologie Dynamique General Circulation Model (LMD-GCM) to simulate the sulphur chemistry during the Indian Ocean Experiment (INDOEX) Intensive Field Phase-1999 (INDOEX-IFP). The originality of this module is its ability to predict particle mass and number concentration for the Aitken and accumulation modes. The model qualitatively reproduces the spatial patterns of observations on sulphate aerosol during INDOEX. On the basis of size distribution retrieved from the observations made along the cruise route during 1998 and 1999, the model successfully simulates the order of magnitude and the general north-south gradient in aerosol number concentration. The result shows the southward migration of minimum concentrations, which follows ITCZ (Inter Tropical Convergence Zone) migration. Sulphate surface concentration during INDOEX-IFP at Kaashidhoo (73.46° E, 4.96° N) gives an agreement within a factor of 2 to 3. Predicted sulphate aerosol optical depth (AOD) matches reasonably with measured values, indicating the capability of this model to predict the vertically integrated column sulphate burden. The Indian contribution to estimated sulphate burden over India is more than 60% with values upto 40% over the Arabian Sea.
10
Ramstein, G., F. Fluteau i V. Masson. "Existence of an ice cap during the mid-Cretaceous period (120–90 Ma): an AGCM investigation". Annals of Glaciology 25 (1997): 198–202. http://dx.doi.org/10.3189/s0260305500014038.
Streszczenie:
Many questions remain concerning whether or not an ice cap existed during the mid-Cretaceous period (120–90 Ma). Other than data and observations from ice-rafted materials, atmospheric general circulation models (AGCMs) may be appropriate tools to investigate whether changes in atmospheric composition, land-sea distribution, or oceanic circulation (used as boundary conditions to constrain the model), provide the climatic conditions that enable ice caps to be formed.This study uses an AGCM developed by the Laboratoire de Météorologie Dynamique (LMD) to perform a set of numerical sensitivity experiments to investigate plate tectonics (land–sea distribution and orography), CO2 partial pressure in the atmosphere and changes in prescribed sea-surface temperatures. The main goals are to quantify the effect of each forcing factor on the increase of Northern Hemisphere high-latitude temperatures, and to investigate whether combining these factors produce temperatures that would allow the ice-sheet formation.
11
Ramstein, G., F. Fluteau i V. Masson. "Existence of an ice cap during the mid-cretaceous period (120–90 Ma): an AGCM investigation". Annals of Glaciology 25 (1997): 198–202. http://dx.doi.org/10.1017/s0260305500014038.
Streszczenie:
Many questions remain concerning whether or not an ice cap existed during the mid-Cretaceous period (120–90 Ma). Other than data and observations from ice-rafted materials, atmospheric general circulation models (AGCMs) may be appropriate tools to investigate whether changes in atmospheric composition, land-sea distribution, or oceanic circulation (used as boundary conditions to constrain the model), provide the climatic conditions that enable ice caps to be formed. This study uses an AGCM developed by the Laboratoire Météorologie Dynamique (LMD) to perform a set of numerical sensitivity experiments to investigate plate tectonics (land-sea distribution and orography), CO2 partial pressure in the atmosphere and changes in prescribed sea-surface temperatures. The main goals are to quantify the effect of each forcing factor on the increase of Northern Hemisphere high-latitude temperatures, and to investigate whether combining these factors produce temperatures that would allow the ice-sheet formation.
12
Gao, Jing, V. Masson-Delmotte, T. Yao, L. Tian, C. Risi i G. Hoffmann. "Precipitation Water Stable Isotopes in the South Tibetan Plateau: Observations and Modeling*". Journal of Climate 24, nr 13 (1.07.2011): 3161–78. http://dx.doi.org/10.1175/2010jcli3736.1.
Streszczenie:
Abstract Measurements of precipitation isotopic composition have been conducted on a daily basis for 1 yr at Bomi, in the southeast Tibetan Plateau, an area affected by the interaction of the southwest monsoon, the westerlies, and Tibetan high pressure systems, as well as at Lhasa, situated west of Bomi. The measured isotope signals are analyzed both on an event basis and on a seasonal scale using available meteorological information and airmass trajectories. The processes driving daily and seasonal isotopic variability are investigated using multidecadal climate simulations forced by twentieth-century boundary conditions and conducted with two different isotopic atmospheric general circulation models [the isotopic version of the Laboratoire de Météorologie Dynamique GCM (LMDZiso) and the ECHAM4iso model]. Both models use specific nudging techniques to mimic observed atmospheric circulation fields. The models simulate a wet and cold bias on the Tibetan Plateau together with a dry bias in its southern part. A zoomed LMDZ simulation conducted with ~50-km local spatial resolution dramatically improves the simulation of isotopic compositions of precipitation on the Tibetan Plateau. Simulated water isotope fields are compared with new data and with previous observations, and regional differences in moisture origins are analyzed using back-trajectories. Here, the focus is on relationships between the water isotopes and climate variables on an event and seasonal scale and in terms of spatial and altitudinal isotopic gradients. Enhancing the spatial resolution is crucial for improving the simulation of the precipitation isotopic composition.
13
Osborne, Joseph H. "Observations on chromate conversion coatings from a sol–gel perspective". Progress in Organic Coatings 41, nr 4 (maj 2001): 280–86. http://dx.doi.org/10.1016/s0300-9440(01)00143-6.
14
Masson, Valéry, i Aude Lemonsu. "Comment Joël Noilhan a influencé la modélisation et les études en climat urbain". La Météorologie, nr 108 (2020): 093. http://dx.doi.org/10.37053/lameteorologie-2020-0022.
Streszczenie:
Bien que ce fait soit peu connu, Joël Noilhan a commencé sa carrière non pas dans l'étude de la végétation, mais dans celle du climat urbain. Ses résultats de thèse sur les échanges radiatifs entre les différentes faces d'un bâtiment, le ciel et le sol sont encore utilisés comme hypothèses dans la plupart des modèles de canopée urbaine, comme celui développé au CNRM, Town Energy Balance (TEB). Joël a contribué dans les années 2000 à l'essor de la météorologie urbaine au CNRM. Il a notamment encouragé les collaborations internationales avec l'équipe canadienne du professeur Tim Oke, spécialiste mondial du climat urbain, et initié un volet expérimental dédié à l'urbain sur la ville de Marseille, lors de la campagne Escompte en 2001. This is not well known, but Joël Noilhan did not start his career by studying vegetation processes, but rather urban climate. His PhD results on radiative exchanges around a building still form the basis of radiative processes in most urban canopy models such as the Town Energy Balance (TEB) developed at CNRM. In the 2000s, he contributed to the urban climate studies at CNRM. He encouraged an international collaboration with the team of Tim Oke, in Canada, an international expert in urban climate. He also initiated an experimental component dedicated to urban environment over the city of Marseille, during the Escompte campaign in 2001.
15
Krinner, Gerhard, i Christophe Genthon. "The Antarctic surface mass balance in a stretched grid general circulation model". Annals of Glaciology 25 (1997): 73–78. http://dx.doi.org/10.3189/s0260305500013823.
Streszczenie:
The Laboratoire de Météorologie Dynamique (LMD) variable-grid atmospheric general circulation model (AGCM) was used in this study for a five-year high-resolution simulation of the Antarctic climate. The horizontal resolution is about 100 km over a large part of the ice sheet. This study focuses on the simulated surface mass balance (precipitation-evaporation sublimation-melt) and on the spatial and temporal variability of snowfall in Antarctica. The simulated annual mean surface mass balance for the whole continent is close to the observed value, and the model simulates well the spatial distribution of the surface mass balance. The annual cycle of snowfall exhibits a clear minimum in summer over the high interior plateau as well as for Antarctica as a whole, in agreement with the observations. In the interior of the continent, the model produces a permanent light background snowfall that accounts for about 5% of the total annual precipitation. The bulk of the snowfall is produced irregularly during periods that generally last only two or three days that are caused by cyclones off the coast.
16
Krinner, Gerhard, i Christophe Genthon. "The Antarctic surface mass balance in a stretched grid general circulation model". Annals of Glaciology 25 (1997): 73–78. http://dx.doi.org/10.1017/s0260305500013823.
Streszczenie:
The Laboratoire de Météorologie Dynamique (LMD) variable-grid atmospheric general circulation model (AGCM) was used in this study for a five-year high-resolution simulation of the Antarctic climate. The horizontal resolution is about 100 km over a large part of the ice sheet. This study focuses on the simulated surface mass balance (precipitation-evaporation sublimation-melt) and on the spatial and temporal variability of snowfall in Antarctica. The simulated annual mean surface mass balance for the whole continent is close to the observed value, and the model simulates well the spatial distribution of the surface mass balance. The annual cycle of snowfall exhibits a clear minimum in summer over the high interior plateau as well as for Antarctica as a whole, in agreement with the observations. In the interior of the continent, the model produces a permanent light background snowfall that accounts for about 5% of the total annual precipitation. The bulk of the snowfall is produced irregularly during periods that generally last only two or three days that are caused by cyclones off the coast.
17
Majerová, Jana, Dorothea Sklenářová i Lenka Nevřivová. "The Effect of the Type of Gelling Agent on the Speed of Gelation of Sol-Gels". Solid State Phenomena 351 (27.10.2023): 47–52. http://dx.doi.org/10.4028/p-uy2ycr.
Streszczenie:
This article deals with the selection of a suitable gelling agent for refractory castable with a sol-gel binder system. The goal is to find the optimal ratio between gelation time, content, and concentration of the solution. Various salts (NaCl, NH4Cl, Ca(NO3)2) are investigated as gelling agents. Gelation curves are constructed from gelation time observations. For the design of the formula of refractory castable with a sol-gel bond, it is important to know the behavior of the sol after mixing with the gelling agent. This is the goal of the experiment. In the end, we will obtain initial data for further proposals for the composition of refractory castable with a sol-gel bond.
18
Trabelsi, Nadia, Imen Hentati, Ibtissem Triki i Moncef Zairi. "Étude de la vulnérabilité à la pollution du système phréatique du sahel de Sfax par les outils SIG". Revue Internationale de Géomatique 29, nr 3-4 (lipiec 2019): 317–38. http://dx.doi.org/10.3166/rig.2019.00087.
Streszczenie:
Le système phréatique du sahel de Sfax (Tunisie) constitue une source importante d’approvisionnement. Ces eaux ne cessent d’être menacées par la pollution nitrique. Dans le but de protéger cet aquifère, une étude de la vulnérabilité intrinsèque a été effectuée. Pour cela on a eu recours à l’utilisation de la méthode SI (Susceptibility Index) qui prend en considération les différents critères de vulnérabilités, régissant le processus de transfert de contaminants. Il s’agit des facteurs géologiques, hydrogéologiques, d’occupation du sol, de la topographie, ainsi que de la météorologie. Dans la présente étude, une modification de la méthode SI a été faite. Une méthode dérivée du modèle SI est présentée (SI modifié). Elle repose sur une démarche qui intègre la modélisation hydrologique sous Agriflux et les SIG. Le divers recours aux SIG a permis l’exécution des différentes opérations de calcul de débits, la création de bases de données ainsi que la cartographie des paramètres influençant la vulnérabilité. L’analyse de la carte de vulnérabilité a permis de distinguer trois zones de degrés de vulnérabilité différents allant du faible au très vulnérable. Les indices SI standard et SI modifié sont combinés, les deux indices de vulnérabilité sont mis en perspective et la pertinence des paramètres utilisés pour chacun est discutée. La cohérence des indices est comparée avec l’occurrence des nitrates dans la plaine de Sfax. La nouvelle carte a permis d’obtenir une meilleure corrélation entre les concentrations en nitrates mesurées et les zones vulnérables par rapport à la méthode originale.
19
Al Dwayyan, A. S., M. Naziruddin Khan i M. S. Al Salhi. "Optical Characterization of Chemically Etched Nanoporous Silicon Embedded in Sol-Gel Matrix". Journal of Nanomaterials 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/713203.
Streszczenie:
Nanoporous (NPs) silicon fabricated by chemical etching process in HF acid was first separated in tetrahydrofuran (THF) solvent and then incorporated into SiO2matrix. The matrix was prepared by sol gel process in which dimethylformamide (DMF) was used as drying chemical control additive (DCCA) to form crack-free dried sample. We examined the optical properties of NPs in three medium which are solvent, sol, and dried sol gel. Our observations reveal that absorption spectra of NPs silicon in THF are modified with respect to the spectra in sol gel. Significant stability in PL of NPs silicon in the sol gel is observed. Influence of matrix environment on peaks of NPs is also discussed. Surface morphology is characterized by field emission scanning electron microscopy (FESEM) which shows that the NPs silicon in THF is similar to the sol gel but becomes aggregation particle to particle. Presence of Si nanoparticles in THF and sol is confirmed by Transmission electron microscopy (TEM). The NPs silicons have mono dispersive and high crystalline nature with spherical shape of around 5 nm in sizes.
20
Lee, K. J., Y. T. Chen, H. Z. Cheng, Jason S. C. Jang, P. C. Chang, S. W. Lin i Y. D. Chen. "Effect of Calcining Temperature of Ceramic Powders Prepared from TEOS/Boehmite Sol-Gel on Tribological Behavior of Brake Lining Materials". Materials Science Forum 638-642 (styczeń 2010): 950–55. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.950.
Streszczenie:
This study is to investigate tribological behavior of brake lining materials by hot pressing commercial friction powders with ceramic powders prepared by TEOS / boehmite sol-gel. The stoichiometric ratios of TEOS / boehmite sol-gel were kept constant but calcinated at different temperature to fabricate different homemade ceramic powders. The various phases of ceramic powders such as γ-Al2O3, δ-Al2O3, θ-Al2O3, α-Al2O3, cristobalite and mullite were formed during the preparation process starting from TEOS / boehmite sol-gel solution. The XRD observations reveal the final compositions of these homemade powders were strongly related to the calcining temperature. The brake lining specimens made from TEOS / boehmite sol-gel calcinated at higher temperature show better tribological performance. The brake lining specimen with α-Al2O3 and mullite which were transformed from TEOS / boehmite sol-gel calcinated at 1300°C shows the most stable friction coefficient and the lowest mass loss during wear tests.
21
Lam, K. S., Dennis Lo i K. H. Wong. "Observations of near-UV superradiance emission from dye-doped sol-gel silica". Optics Communications 121, nr 4-6 (grudzień 1995): 121–24. http://dx.doi.org/10.1016/0030-4018(95)00459-7.
22
Perez, Monica A., Jesper Lundbye-Jensen i Jens B. Nielsen. "Task-Specific Depression of the Soleus H-Reflex After Cocontraction Training of Antagonistic Ankle Muscles". Journal of Neurophysiology 98, nr 6 (grudzień 2007): 3677–87. http://dx.doi.org/10.1152/jn.00988.2007.
Streszczenie:
Ballet dancers have small soleus (SOL) H-reflex amplitudes, which may be related to frequent use of cocontraction of antagonistic ankle muscles. Indeed, SOL H-reflexes are depressed during cocontraction compared with plantarflexion at matched background EMG level. We investigated the effect of 30-min training of simultaneous activation of ankle dorsi- and plantarflexor muscles (cocontraction task) on the SOL H-reflex in 10 healthy volunteers. Measurements were taken during cocontraction. After training, there was a significant improvement in the ability of the subjects to perform a stable cocontraction. SOL H-reflex recruitment curves and H-max/M-max ratios were decreased after cocontraction training but not after 30 min of static dorsi or plantarflexion. The decreased H-reflex size correlated with improved motor performance. No changes in SOL and tibialis anterior (TA) EMG activity or EMG power were observed, suggesting that increased presynaptic inhibition of Ia afferents is a likely mechanism for H-reflex depression. In different sessions we measured SOL and TA motor-evoked potentials (MEPs) by using transcranial magnetic stimulation (TMS), TMS-elicited suppression of SOL EMG, and coherence between electroencephalographic (EEG) activity (Cz) and TA and SOL EMG. SOL and TA MEPs were depressed, whereas TMS-elicited suppression of SOL EMG and coherence were increased after training. Decreased excitability of corticospinal neurons due to increased intracortical inhibition seems a likely explanation of these observations. Our results indicate that the depression in H-reflex observed during a cocontraction task can be trained and that repeated performance of tasks involving cocontraction may lead to prolonged changes in reflex and corticospinal excitability.
23
Beck, Jeffrey, Mathieu Nuret i Olivier Bousquet. "Model Wind Field Forecast Verification Using Multiple-Doppler Syntheses from a National Radar Network". Weather and Forecasting 29, nr 2 (1.04.2014): 331–48. http://dx.doi.org/10.1175/waf-d-13-00068.1.
Streszczenie:
Abstract Model verification has traditionally relied upon in situ observations, which typically exist on a sparse network, making nonsurface model forecast verification difficult. Given increasing model resolution, supplemental observational datasets are needed. Multiple-Doppler wind retrievals using a national network of radars provide an opportunity to assess the accuracy of wind forecasts at multiple levels, as well as verification within a three-dimensional domain. Wind speed and direction verification results are presented for a 9-day period of forecasts from the French Application of Research to Operations at Mesoscale-Western Mediterranean (AROME-WMED) model using multiple-Doppler retrievals from the French Application Radar à la Météorologie Infrasynoptique (ARAMIS) network. For the analyzed period, relationships were found that suggest that errors are not only linked to forecasted evolution of meteorological phenomena, but are sensitive to terrain height below the analyzed level as well as mesoscale processes. The spatial distribution of errors at initialization and forecast times shows that biases are generally independent of location and terrain height at initialization, but that the impact of terrain below the analysis level affects the forecasted wind magnitude and direction over time. These comparisons illustrate that multiple-Doppler wind retrieval measurements accurately identify model error and can serve as an invaluable dataset for model verification.
24
Gomez-Villalba, L. S., A. Sierra-Fernandez, P. Quintana, M. E. Rabanal i R. Fort. "Correlation between microstructure and cathodoluminescence properties of Mg(OH)2 (brucite) nanoparticles: effect of synthesis method". CrystEngComm 20, nr 37 (2018): 5632–40. http://dx.doi.org/10.1039/c8ce00942b.
Streszczenie:
The study shows a correlation between microstructure, atomic-scale observations and intrinsic cathodoluminescence from two types of nano-brucite (Mg(OH)2) synthesized by hydrothermal and sol–gel methods, and a third one that was commercially acquired.
25
Bravo, S., i A. Hewish. "Geomagnetic storms forecast using IPS observations". Geofísica Internacional 27, nr 2 (1.04.1988): 191–98. http://dx.doi.org/10.22201/igeof.00167169p.1988.27.2.782.
Streszczenie:
La observación del centelleo interplanetario (IPS) de radiofrecuencias estelares de diámetro pequeño permite la detección y el rastreo de perturbaciones en el viento solar que viajan desde los hoyos coronales en el Sol hacia la Tierra, causando a su llegada perturbaciones geomagnéticas e ionosféricas. Durante el periodo de julio de 1978 a septiembre de 1979, se llevo a cabo un monitoreo continuo del centelleo de 900 fuentes estelares de radio y se encontró que la mayoría de los comienzos repentinos (SC) de tormentas geomagnéticas ocurrieron más de un día después, y algunos hasta cuatro o cinco días después de que se detecto por primera vez la perturbación en el medio interplanetario a través del centelleo. Esto demuestra que un monitoreo permanente del dentelleo interplanetario de las radiofuentes proporciona una herramienta muy útil en el pronóstico de las perturbaciones geomagnéticas y los efectos asociados a ellas.
26
Lorenzon, Paola, Sandra Furlan, Barbara Ravara, Alessandra Bosutti, Gabriele Massaria, Annalisa Bernareggi, Marina Sciancalepore i in. "Preliminary Observations on Skeletal Muscle Adaptation and Plasticity in Homer 2-/- Mice". Metabolites 11, nr 9 (19.09.2021): 642. http://dx.doi.org/10.3390/metabo11090642.
Streszczenie:
Homer represents a diversified family of scaffold and transduction proteins made up of several isoforms. Here, we present preliminary observations on skeletal muscle adaptation and plasticity in a transgenic model of Homer 2-/- mouse using a multifaceted approach entailing morphometry, quantitative RT-PCR (Reverse Transcription PCR), confocal immunofluorescence, and electrophysiology. Morphometry shows that Soleus muscle (SOL), at variance with Extensor digitorum longus muscle (EDL) and Flexor digitorum brevis muscle (FDB), displays sizable reduction of fibre cross-sectional area compared to the WT counterparts. In SOL of Homer 2-/- mice, quantitative RT-PCR indicated the upregulation of Atrogin-1 and Muscle ring finger protein 1 (MuRF1) genes, and confocal immunofluorescence showed the decrease of neuromuscular junction (NMJ) Homer content. Electrophysiological measurements of isolated FDB fibres from Homer 2-/- mice detected the exclusive presence of the adult ε-nAChR isoform excluding denervation. As for NMJ morphology, data were not conclusive, and further work is needed to ascertain whether the null Homer 2 phenotype induces any endplate remodelling. Within the context of adaptation and plasticity, the present data show that Homer 2 is a co-regulator of the normotrophic status in a muscle specific fashion.
27
Filion, Louise, i Serge Payette. "Observations sur les caractéristiques physiques du couvert de neige et sur le régime thermique du sol à Poste-de-la-Baleine, Nouveau-Québec". Géographie physique et Quaternaire 32, nr 1 (17.01.2011): 71–79. http://dx.doi.org/10.7202/1000289ar.
Streszczenie:
Les auteurs présentent des observations effectuées sur les caractéristiques physiques du couvert de neige (hiver 1973-1974) et le régime thermique du sol (automne 1973 — été 1975) à Poste-de-la-Baleine, Nouveau-Québec. En milieu ouvert, le couvert de neige est plus dense qu’en milieu forestier. Cette caractéristique conditionne l’efficacité de son pouvoir isolant. En forêt, le pouvoir isolant du couvert de neige est relativement élevé; de la surface de la neige à la base du profil, s’établit un gradient marqué que traduisent une augmentation de la température et de la densité du couvert de neige, de même que l’accroissement de la taille des particules. Le gradient est le plus fort en janvier; il est faible ou nul l’automne et au moment de la fonte printanière. Les courbes permettant de caractériser le régime thermique du sol sous un couvert forestier démontrent que le refroidissement du sol est un processus plus lent que son réchauffement. La température enregistrée sous la couronne d’un arbre à 7 cm de la surface est nettement inférieure à celle enregistrée dans une ouverture de la forêt; elle démontre l’effet de l’interception des rayons solaires et de la neige par le feuillage sur le régime thermique du sol.
28
O'Donovan, M. J., M. J. Pinter, R. P. Dum i R. E. Burke. "Kinesiological studies of self- and cross-reinnervated FDL and soleus muscles in freely moving cats". Journal of Neurophysiology 54, nr 4 (1.10.1985): 852–66. http://dx.doi.org/10.1152/jn.1985.54.4.852.
Streszczenie:
The activity patterns in self- and cross-reinnervated flexor digitorum longus (FDL) and soleus (SOL) muscles were examined during natural movements in awake, unrestrained cats in which electromyographic (EMG) electrodes, tendon-force gauges, and muscle-length gauges had been chronically implanted under anesthesia and aseptic conditions. Kinesiological data were recorded between 13 and 22 mo after nerve surgery. Self-reinnervated FDL and SOL muscles (i.e., FDL----FDL and SOL----SOL, respectively) exhibited locomotor activity patterns that were the same as observed in normal, unoperated FDL and SOL muscles (26). FDL----FDL muscles exhibited primarily brief bursts of activity in early swing, just after the toes had left the ground, whereas SOL----SOL muscles showed bursts of activity just before and during stance. In contrast, the cross-reinnervated muscles (both SOL----FDL and FDL----SOL) that had little or no unwanted self-reinnervation showed the patterns of activity that are associated with the innervating foreign motoneurons. That is, cross-reinnervated SOL----FDL muscles were intensely active in quadrupedal standing and, during the stance phase of stepping, producing large force transients while actively lengthening. Conversely, cross-reinnervated FDL----SOL muscles were active mainly in short bursts at the onset of the swing phase of stepping, just after the foot had left the ground. There was considerable modulation of EMG and peak force output in FDL----SOL muscles with changing speed of locomotion, whereas little modulation was evident in SOL----FDL muscles. The activity patterns in self- and cross-reinnervated FDL and SOL muscles were also recorded during scratch and paw-shaking reflexes. As in locomotion, the observed patterns were in all cases consistent with those expected for the innervating motor pool rather than the innervated muscle. Muscles that had been dually reinnervated by both the original and foreign motor pools displayed activity patterns that were a mixture of the FDL and SOL activity patterns described above. The present results demonstrate that motoneuron activation patterns remain qualitatively unaltered when their motor axons reinnervate foreign muscles. In addition, the observations permit some quantitative estimates of the degree to which cross-reinnervated muscles are subjected to patterns of motoneuron activity and to conditions of mechanical loading that are markedly different from those in the self-reinnervated or normal conditions.
29
Reena, V. N., H. Misha, G. S. Bhagyasree i B. Nithyaja. "Enhanced photoluminescence and color tuning from Rhodamine 6G-doped sol–gel glass matrix via DNA templated CdS nanoparticles". AIP Advances 12, nr 10 (1.10.2022): 105217. http://dx.doi.org/10.1063/5.0123529.
Streszczenie:
High-performance organic solid-state lasers can be fabricated using a variety of host and luminophore combinations. Rhodamine 6G is a promising candidate for tunable solid-state laser materials. It may, however, degrade faster when exposed to light. Sol–gel is a technique for fabricating glasses at low temperatures that prevent organic dyes from degrading. This work investigates the effect of deoxyribonucleic acid-capped cadmium sulfide nanoparticles on the photoluminescence of Rhodamine 6G-doped sol–gel glass. The samples were characterized by absorption spectroscopy, scanning electron microscopy, and powder x-ray diffraction. The chromaticity studies of the samples were carried out to evaluate the Commission International d’Eclairage coordinates, color correlation temperature, and color purity values. The photoluminescence studies of Rhodamine 6G-doped sol–gel glasses show enhancement in intensity and tuning of emission wavelength in the presence of cadmium sulfide nanoparticles. The annealing temperature effect on the photoluminescence was also investigated. The studies and observations have revealed the possibility of using CdS-incorporated Rhodamine 6G-doped sol–gel-derived glass as a tunable material for organic solid-state lasers.
30
Calpini, B., D. Ruffieux, J. M. Bettems, C. Hug, P. Huguenin, H. P. Isaak, P. Kaufmann, O. Maier i P. Steiner. "Ground-based remote sensing profiling and numerical weather prediction model to manage nuclear power plants meteorological surveillance in Switzerland". Atmospheric Measurement Techniques Discussions 4, nr 1 (28.01.2011): 789–813. http://dx.doi.org/10.5194/amtd-4-789-2011.
Streszczenie:
Abstract. The meteorological surveillance of the four nuclear power plants in Switzerland is of first importance in a densely populated area such as the Swiss Plateau. The project "Centrales Nucléaires et Météorologie" CN-MET aimed at providing a new security tool based on one hand on the development of a high resolution numerical weather prediction (NWP) model. The latter is providing essential nowcasting information in case of a radioactive release from a nuclear power plant in Switzerland. On the other hand, the model input over the Swiss Plateau is generated by a dedicated network of surface and upper air observations including remote sensing instruments (wind profilers and temperature/humidity passive microwave radiometers). This network is built upon three main sites ideally located for measuring the inflow/outflow and central conditions of the main wind field in the planetary boundary layer over the Swiss Plateau, as well as a number of surface automatic weather stations (AWS). The network data are assimilated in real-time into the fine grid NWP model using a rapid update cycle of eight runs per day (one forecast every 3 h). This high resolution NWP model has replaced the former security tool based on in situ observations (in particular one meteorological mast at each of the power plant) and a local dispersion model. It is used to forecast the dynamics of the atmosphere in the planetary boundary layer (typically the first 4 km above ground layer) and over a time scale of 24 h. This tool provides at any time (e.g. starting at the initial time of a nuclear power plant release) the best picture of the 24-h evolution of air mass over the Swiss Plateau and furthermore generates the input data (in the form of simulated values substituting in situ observations) required for the local dispersion model used at each of the nuclear power plants locations. This paper is presenting the concept and two validation studies as well as the results of an emergency response exercise performed in winter 2009.
31
Calpini, B., D. Ruffieux, J. M. Bettems, C. Hug, P. Huguenin, H. P. Isaak, P. Kaufmann, O. Maier i P. Steiner. "Ground-based remote sensing profiling and numerical weather prediction model to manage nuclear power plants meteorological surveillance in Switzerland". Atmospheric Measurement Techniques 4, nr 8 (23.08.2011): 1617–25. http://dx.doi.org/10.5194/amt-4-1617-2011.
Streszczenie:
Abstract. The meteorological surveillance of the four nuclear power plants in Switzerland is of first importance in a densely populated area such as the Swiss Plateau. The project "Centrales Nucléaires et Météorologie" CN-MET aimed at providing a new security tool based on one hand on the development of a high resolution numerical weather prediction (NWP) model. The latter is providing essential nowcasting information in case of a radioactive release from a nuclear power plant in Switzerland. On the other hand, the model input over the Swiss Plateau is generated by a dedicated network of surface and upper air observations including remote sensing instruments (wind profilers and temperature/humidity passive microwave radiometers). This network is built upon three main sites ideally located for measuring the inflow/outflow and central conditions of the main wind field in the planetary boundary layer over the Swiss Plateau, as well as a number of surface automatic weather stations (AWS). The network data are assimilated in real-time into the fine grid NWP model using a rapid update cycle of eight runs per day (one forecast every three hours). This high resolution NWP model has replaced the former security tool based on in situ observations (in particular one meteorological mast at each of the power plants) and a local dispersion model. It is used to forecast the dynamics of the atmosphere in the planetary boundary layer (typically the first 4 km above ground layer) and over a time scale of 24 h. This tool provides at any time (e.g. starting at the initial time of a nuclear power plant release) the best picture of the 24-h evolution of the air mass over the Swiss Plateau and furthermore generates the input data (in the form of simulated values substituting in situ observations) required for the local dispersion model used at each of the nuclear power plants locations. This paper is presenting the concept and two validation studies as well as the results of an emergency response exercise performed in winter 2009.
32
Yoldas, Bulent E. "Photoluminescence in chemically polymerized SiO2 and Al2O3–SiO2 systems". Journal of Materials Research 5, nr 6 (czerwiec 1990): 1157–58. http://dx.doi.org/10.1557/jmr.1990.1157.
Streszczenie:
It is observed that in sol-gel derived oxide systems, chemical processes lead to the formation of photoluminescent centers analogous to those produced by neutron or γ-irradiation of oxide crystals, fused silica, and other glasses. The initial observations about the phenomenon and its proposed mechanism are reported here.
33
Arakelian, Ara, i Francis Codron. "Southern Hemisphere Jet Variability in the IPSL GCM at Varying Resolutions". Journal of the Atmospheric Sciences 69, nr 12 (1.12.2012): 3788–99. http://dx.doi.org/10.1175/jas-d-12-0119.1.
Streszczenie:
Abstract Fluctuations of the Southern Hemisphere eddy-driven jet are studied in a suite of experiments with the Laboratoire de Météorologie Dynamique, version 4 (LMDZ4) atmospheric GCM with varying horizontal resolution, in coupled mode and with imposed SSTs. The focus is on the relationship between changes in the mean state brought by increasing resolution, and the intraseasonal variability and response to increasing CO2 concentration. In summer, the mean jet latitude moves poleward when the resolution increases in latitude, converging toward the observed one. Most measures of the jet dynamics, such as skewness of the distribution or persistence time scale of jet movements, exhibit a simple dependence on the mean jet latitude and also converge to the observed values. In winter, the improvement of the mean-state biases with resolution is more limited. In both seasons, the relationship between the dominant mode of variability—the southern annular mode (SAM)—and the mean state remains the same as in observations, except in the most biased winter simulation. The jet fluctuations—latitude shifts or splitting—just occur around a different mean position. Both the model biases and the response to increasing CO2 project strongly onto the SAM structure. No systematic relation between the amplitude of the response and characteristics of the control simulation was found, possibly due to changing dynamics or impacts of the physical parameterizations with different resolutions.
34
Cámara, Alvaro de la, François Lott, Valérian Jewtoukoff, Riwal Plougonven i Albert Hertzog. "On the Gravity Wave Forcing during the Southern Stratospheric Final Warming in LMDZ". Journal of the Atmospheric Sciences 73, nr 8 (26.07.2016): 3213–26. http://dx.doi.org/10.1175/jas-d-15-0377.1.
Streszczenie:
Abstract The austral stratospheric final warming date is often predicted with substantial delay in several climate models. This systematic error is generally attributed to insufficient parameterized gravity wave (GW) drag in the stratosphere around 60°S. A simulation with a general circulation model [Laboratoire de Météorologie Dynamique zoom model (LMDZ)] with a much less pronounced bias is used to analyze the contribution of the different types of waves to the dynamics of the final warming. For this purpose, the resolved and unresolved wave forcing of the middle atmosphere during the austral spring are examined in LMDZ and reanalysis data, and a good agreement is found between the two datasets. The role of parameterized orographic and nonorographic GWs in LMDZ is further examined, and it is found that orographic and nonorographic GWs contribute evenly to the GW forcing in the stratosphere, unlike in other climate models, where orographic GWs are the main contributor. This result is shown to be in good agreement with GW-resolving operational analysis products. It is demonstrated that the significant contribution of the nonorographic GWs is due to highly intermittent momentum fluxes produced by the source-related parameterizations used in LMDZ, in qualitative agreement with recent observations. This yields sporadic high-amplitude GWs that break in the stratosphere and force the circulation at lower altitudes than more homogeneously distributed nonorographic GW parameterizations do.
35
Hashim, A. S., B. Azahari, Y. Ikeda i S. Kohjiya. "The Effect of Bis(3-Triethoxysilylpropyl) Tetrasulfide on Silica Reinforcement of Styrene-Butadiene Rubber". Rubber Chemistry and Technology 71, nr 2 (1.05.1998): 289–99. http://dx.doi.org/10.5254/1.3538485.
Streszczenie:
Abstract Bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) was found to affect the curing characteristics and the physical properties of styrene-butadiene (SBR) gum rubber and xin situ silica-filled SBR vulcanizates. Silica incorporated by the in situ sol-gel reaction of tetraethoxysilane with TESPT showed a much higher reinforcing efficiency than did conventional mechanical mixing and the in situ method without TESPT. The higher reinforcing efficiency is attributed to the formation of a silica-rubber network, which also changed the dynamic mechanical behavior of the SBR vulcanizates. Transmission electron microscopy observations showed in situ silica incorporation of very fine particles in comparison to the sol-gel process without TESPT.
36
Echer, E., N. J. Schuch, K. Makita i S. Okano. "Observations of broadband solar UV-A irradiance at Santa Maria, Brazil (29°S, 53° W)". Geofísica Internacional 43, nr 1 (1.01.2004): 53–59. http://dx.doi.org/10.22201/igeof.00167169p.2004.43.1.214.
Streszczenie:
Se llevaron a cabo observaciones de la irradiancia solar en la banda UV-A (320-400 nm) en Santa Maria, Brasil (29° S, 53° W) entre septiembre 1993 y diciembre 1996. Se usaron dos técnicas de medición diferentes: la de Sol directo (DS) con el sensor apuntado directamente al Sol, y la de cenit (ZS), con el sensor señalando hacia el cenit. Se analiza la variación estacional de la irradiancia en UV-A DS y ZS en el mediodía local. Ambas irradiancias UV-A DS y ZS tienen una fuerte variación estacional que está anticorrelacionada con la variación del ángulo cenital. Se muestra que la irradiancia UV-A ZS tiene una variación estacional mayor que la irradiancia UV-A DS, con razones verano/invierno de 3.4 para UV-A ZS y 1.4 para UV-A DS. Esta diferencia se debe al arreglo geométrico de las observaciones; la irradiancia UV-A DS se mide siguiendo al Sol y su variabilidad se debe a la variación del camino óptico atmosférico a lo largo del año. La irradiancia UV-A ZS es la irradiancia difusa medida apuntando a una dirección fija , el cenit, y además de la varaición del camino óptico atmosférico, la componente de la irradiancia directa incidente sobre la superficie horizontal tiene también una variación con el ángulo cenital solar. Analizando las irradiancias UV-A DS y ZS en función el ángulo cenital solar, se observa que UV-A ZS decrece más rápido conforme mayor es el ángulo, en comparación con UV-A DS. Cálculos usando la Ley de Beer a 370 nm, muestran un comportamiento similar para irradiancias en una superficie horizontal al rayo solar incidente, comparados con UV-A ZS, y en una superficie perpendicular al rayo incidente comparados con la irradiancia UV-A DS.
37
Dum, R. P., M. J. O'Donovan, J. Toop i R. E. Burke. "Cross-reinnervated motor units in cat muscle. I. Flexor digitorum longus muscle units reinnervated by soleus motoneurons". Journal of Neurophysiology 54, nr 4 (1.10.1985): 818–36. http://dx.doi.org/10.1152/jn.1985.54.4.818.
Streszczenie:
The properties of flexor digitorum longus (FDL) muscles and of individual motor units were studied in cats 30-50 wk after self-reinnervation by FDL motoneurons (FDL----FDL) or cross-reinnervation by soleus (SOL) motoneurons (SOL----FDL). Individual motor units were functionally isolated by intracellular recording and stimulation of identified SOL alpha-motoneurons. Glycogen-depletion methods permitted histochemical study of muscle fibers belonging to physiologically characterized muscle units. The observations were compared with data from normal cat FDL muscles and motor units (27). Intentionally self-reinnervated FDL muscles (FDL----FDL; n = 5) were normal in size and wet weight. FDL----FDL motor units could be classified into the same physiological categories found in normal FDL [types: fast contracting, fatigable (FF), fast contracting, fatigue resistant (FR), and slow (S); n = 24], with approximately the same proportions as normal. The histochemical muscle fiber types associated with these categories were also qualitatively normal although there was evidence of marked distortion of the normal histochemical mosaic. These data confirm other studies of self-reinnervation and suggest that self-reinnervation can produce complete interconversion of muscle fiber types. Cross-reinnervation of FDL muscle by SOL motoneurons (SOL----FDL; n = 12) produced muscles that were smaller (about half the normal wet weight) and more red than normal. SOL----FDL muscle contracted more slowly than normal or FDL----FDL muscles and had much higher proportions of histochemical type I muscle fibers. In those SOL----FDL muscles, in which little or no unwanted self-reinnervation could be demonstrated, greater than 95% of the muscle fibers were type I. Forty-one individual motor units in SOL----FDL muscles were isolated by intracellular penetration in functionally identified SOL alpha-motoneurons. Their muscle units were all type S by physiological criteria (absence of "sag" in unfused tetani and marked resistance to fatigue). SOL----FDL muscle units had contraction times and fatigue properties that were essentially identical to those of type S units in the normal FDL. All of the seven units, successfully studied by glycogen depletion, exhibited histochemical type I fibers. SOL motoneurons that innervated FDL muscle units had slightly shorter afterhyperpolarization durations than normal SOL cells, but axonal conduction velocities were normal.(ABSTRACT TRUNCATED AT 400 WORDS)
38
Murakami, K., S. Osanai, M. Shigekuni, S. Iio, H. Tanahashi, S. Kohjiya i Y. Ikeda. "Silica and Silane Coupling Agent for in Situ Reinforcement of Acrylonitrile-Butadiene Rubber". Rubber Chemistry and Technology 72, nr 1 (1.03.1999): 119–29. http://dx.doi.org/10.5254/1.3538781.
Streszczenie:
Abstract In situ silica reinforcement for the acrylonitrile-butadiene rubber (NBR) vulcanizates, which were premixed with a conventional silica (VN-3) and γ-mercaptopropyltrimethoxysilane (γ-MPS), was achieved by the sol-gel reaction of tetraethoxysilane (TEOS) using ethylenediamine. It was observed that the reinforcement efficiency tended to increase with the increase of mechanically premixed conventional silica. From the observations of transmission electron microscopy and scanning electron microscopy, the simultaneous use of VN-3 and γ-MPS was found to promote the formation of large silica particles and clusters with a relatively good dispersion by the sol-gel reaction of TEOS in the NBR vulcanizate. The results of hysteresis measurements supported this promotion. It was considered to be due to the surface modification of VN-3 by the sol-gel reaction of TEOS and the presence of γ-MPS which worked as a dispersion agent for silica particles. The relationship between the mechanical properties and the morphology of the in situ silica filled vulcanizates is discussed.
39
Pernes-Debuyser, A., i D. Tessier. "Influence du pH sur les propriétés des sols : l'essai de longue durée des 42 parcelles à Versailles". Revue des sciences de l'eau 15 (12.04.2005): 27–39. http://dx.doi.org/10.7202/705484ar.
Streszczenie:
Les pratiques de fertilisation et d'amendement peuvent contribuer à modifier profondément les propriétés des sols. Ceci est mis en évidence par le dispositif des 42 parcelles de l'INRA à Versailles qui reçoit chaque année les mêmes traitements depuis 1929. Il présente l'originalité d'être en jachère nue. Les résultats reportés ici reposent sur 16 traitements que nous comparons à une parcelle témoin. Le sol est à caractère limoneux avec 14 à 22 % d'argile. Le pH, la capacité d'échange au pH du sol (CECsol), et les cations échangeables ont été mesurés. Des mesures de porosité, de rétention de l'eau à différents potentiels de l'eau ont été effectuées. Des variations considérables de pH sont observées. Les engrais ammoniacaux conduisent à des parcelles très acides (pH 3,5 à 5,0), à faible CECsol, essentiellement saturée par des cations aluminium. Dans les parcelles chaulées ou recevant des amendements basiques, le pH est tamponné à 8,2 par les carbonates. La CECsol double du sol acide au sol chaulé où elle est majoritairement saturée par du calcium échangeable. Avec les sels neutres (par exemple KCl, NaNO3) le pH n'a pas changé et pour le témoin il a légèrement baissé. Des observations de terrain montrent que ces différents états physico-chimiques sont en relation avec les états de surface du sol et influencent la porosité du sol en profondeur. Ainsi dans les sols des régions tempérées la CECsol peut doubler dans un domaine très restreint de pH (6,0 à 7,5), orientant fortement les propriétés physiques des sols.
40
Wu, Jan-Sen, Anthony S. T. Chiang i Tseng-Chang Tsai. "Some Observations on the Synthesis of Colloidal Beta Zeolite from a Clear Precursor Sol". Science of Advanced Materials 3, nr 6 (1.12.2011): 1011–18. http://dx.doi.org/10.1166/sam.2011.1229.
41
Adams, G. R., S. A. McCue, M. Zeng i K. M. Baldwin. "Time course of myosin heavy chain transitions in neonatal rats: importance of innervation and thyroid state". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 276, nr 4 (1.04.1999): R954—R961. http://dx.doi.org/10.1152/ajpregu.1999.276.4.r954.
Streszczenie:
During the postnatal period, rat limb muscles adapt to weight bearing via the replacement of embryonic (Emb) and neonatal (Neo) myosin heavy chains (MHCs) by the adult isoforms. Our aim was to characterize this transition in terms of the six MHC isoforms expressed in skeletal muscle and to determine the importance of innervation and thyroid hormone status on the attainment of the adult MHC phenotype. Neonatal rats were made hypothyroid via propylthiouracil (PTU) injection. In normal and PTU subgroups, leg muscles were unilaterally denervated at 15 days of age. The MHC profiles of plantaris (PLN) and soleus (Sol) muscles were determined at 7, 14, 23, and 30 days postpartum. At day 7, the Sol MHC profile was 55% type I, 30% Emb, and 10% Neo; in the PLN, the pattern was 60% Neo and 25% Emb. By day 30 the Sol and PLN had essentially attained an adult MHC profile in the controls. PTU augmented slow MHC expression in the Sol, whereas in the PLN it markedly repressed IIb MHC by retaining neonatal MHC expression. Denervation blunted the upregulation of IIb in the PLN and of Type I in the Sol and shifted the pattern to greater expression of IIa and IIx MHCs in both muscles. In contrast to previous observations, these findings collectively suggest that both an intact thyroid and innervation state are obligatory for the attainment of the adult MHC phenotype, particularly in fast-twitch muscles.
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Remaud, Marine, Frédéric Chevallier, Anne Cozic, Xin Lin i Philippe Bousquet. "On the impact of recent developments of the LMDz atmospheric general circulation model on the simulation of CO<sub>2</sub> transport". Geoscientific Model Development 11, nr 11 (9.11.2018): 4489–513. http://dx.doi.org/10.5194/gmd-11-4489-2018.
Streszczenie:
Abstract. The quality of the representation of greenhouse gas (GHG) transport in atmospheric general circulation models (GCMs) drives the potential of inverse systems to retrieve GHG surface fluxes to a large extent. In this work, the transport of CO2 is evaluated in the latest version of the Laboratoire de Météorologie Dynamique (LMDz) GCM, developed for the Climate Model Intercomparison Project 6 (CMIP6) relative to the LMDz version developed for CMIP5. Several key changes have been implemented between the two versions, which include a more elaborate radiative scheme, new subgrid-scale parameterizations of convective and boundary layer processes and a refined vertical resolution. We performed a set of simulations of LMDz with different physical parameterizations, two different horizontal resolutions and different land surface schemes, in order to test the impact of those different configurations on the overall transport simulation. By modulating the intensity of vertical mixing, the physical parameterizations control the interhemispheric gradient and the amplitude of the seasonal cycle in the Northern Hemisphere, as emphasized by the comparison with observations at surface sites. However, the effect of the new parameterizations depends on the region considered, with a strong impact over South America (Brazil, Amazonian forest) but a smaller impact over Europe, East Asia and North America. A finer horizontal resolution reduces the representation errors at observation sites near emission hotspots or along the coastlines. In comparison, the sensitivities to the land surface model and to the increased vertical resolution are marginal.
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Montmerle, Thibaut, i Claudia Faccani. "Mesoscale Assimilation of Radial Velocities from Doppler Radars in a Preoperational Framework". Monthly Weather Review 137, nr 6 (1.06.2009): 1939–53. http://dx.doi.org/10.1175/2008mwr2725.1.
Streszczenie:
Abstract This paper presents the results of a preoperational assimilation of radial velocities from Doppler radars of the French Application Radar la Météorologie InfraSynoptique (ARAMIS) network in the nonhydrostatic model, the Application of Research to Operations at Mesoscale (AROME). For this purpose, an observation operator, which allows the simulation of radial winds from the model variables, is included in the three-dimensional variational data assimilation (3DVAR) system. Several data preprocessing procedures are applied to avoid as much as possible erroneous measurements (e.g., due to dealiasing failures) from entering the minimization process. Quality checks and other screening procedures are discussed. Daily monitoring diagnostics are developed to check the status and the quality of the observations against their simulated counterparts. Innovation biases in amplitude and in direction are studied by comparing observed and simulated velocity–azimuth display (VAD) profiles. Experiments over 1 month are performed. Positive impacts on the analyses and on precipitation forecasts are found. Scores against conventional data show mostly neutral results because of the much-localized impact of radial velocities in space and in time. Significant improvements of low-level divergence analysis and on the resulting forecast are found when specific sampling conditions are met: the closeness of convective systems to radars and the orientation of the low-level horizontal wind gradient with respect to the radar beam. Focus on a frontal rainband case study is performed to illustrate this point.
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Diatta, Samo, Frédéric Hourdin, Amadou Thierno Gaye i Nicolas Viltard. "Comparison of Rainfall Profiles in the West African Monsoon as Depicted by TRMM PR and the LMDZ Climate Model". Monthly Weather Review 138, nr 5 (1.05.2010): 1767–77. http://dx.doi.org/10.1175/2009mwr3092.1.
Streszczenie:
Abstract Vertical rainfall profiles obtained with TRMM-PR 2A25 standard products are compared with rain profiles deduced from the Laboratoire de Météorologie Dynamique second generation global climate model (LMDZ, the Z stands for zoom capability) with two parameterization schemes: Emanuel’s and Tiedke’s. This paper focuses on the low layers of the atmosphere over West Africa during the monsoon [June–September (JJAS)]. The precipitation decrease above 4 km is systematically not represented in rainfall profiles generated by Emanuel’s parameterization scheme. However, Emanuel’s scheme shows a decrease similar to the observation from 4 km down to the surface, especially in the Sahel (proper depth of the layer dominated by reevaporation). As for Tiedtke’s scheme, it best describes the downward increase in the upper levels of the atmosphere, whereas the downward decrease in the lower levels begins too low when compared to the observations. Tiedtke’s parameterization shows an overestimation of liquid water production over the ocean and over the Guinean region and a slightly too strong reevaporation in the Sahara and Sahel. The zonal distribution of vertical rain profiles is then biased with this model scheme compared to the 2A25-PR product. On the other hand, although Emanuel’s scheme detects too much reevaporation over the Sahara and underestimates liquid water production over the ocean compared to PR observation, it shows a good meridional distribution of these parameters. This is especially true in the Sahel where Emanuel’s scheme gives the best representation of reevaporation.
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Etchevers, Pierre, François Besson i Jean-Michel Soubeyroux. "Contenu en eau des sols : comparaison des données simulées par SIM2 avec les données observées". La Météorologie, nr 118 (2022): 029. http://dx.doi.org/10.37053/lameteorologie-2022-0058.
Streszczenie:
Le contenu en eau du sol près de la surface, variable essentielle de notre environnement, reste assez méconnu en raison des difficultés pour l'observer. La chaîne de modélisation hydrométéorologique SIM2 permet de le simuler à partir des conditions météorologiques. La comparaison des résultats du modèle avec les observations d'une vingtaine de stations du sud de la France montre une bonne adéquation des deux jeux de données, la dynamique temporelle du contenu en eau du sol étant bien représentée (amplitude et saisonnalité). Les performances de SIM2 se détériorent un peu en été lors de la survenue d'orages intenses très locaux. The water content of the soil near the surface, an essential variable of our environment, remains rather unknown because of the observation difficulties. The hydro-meteorological modeling chain SIM2 allows to simulate it from meteorological conditions. Comparison of the model results with observations from about 20 stations in southern France shows a good match between the two data sets. The temporal dynamics of soil water content is well represented (amplitude and seasonality). The SIM2 performance slightly deteriorates in summer when very local intense thunderstorms occur.
46
Zhou, Yucheng, Etienne Le Calvez, Sun Woong Baek, Matevž Frajnkovič, Camille Douard, Olivier Crosnier, Thierry Brousse i Laurent Pilon. "Effect of Particle Size on Thermodynamics and Lithium Ion Transport in Ti2Nb2O9 Electrodes Synthesized By Solid State or Sol-Gel Method". ECS Meeting Abstracts MA2022-01, nr 2 (7.07.2022): 258. http://dx.doi.org/10.1149/ma2022-012258mtgabs.
Streszczenie:
Ti2Nb2O9 has been identified as a promising lithium-ion battery anode material with large specific capacity, small cycling degradation, and good capacity retention at large currents. This study aims to gain insight into the charging mechanisms as well as the thermodynamics and ion transport in Ti2Nb2O9 synthesized by the solid state or the sol-gel method and formed by particles of different sizes using potentiometric entropy and operando isothermal calorimetric measurements. First, electrochemical testing showed that Ti2Nb2O9 electrodes made by sol-gel synthesis exhibited larger specific capacity, smaller polarization between lithiation/delithiation, and better capacity retention at large currents compared to those made by solid state synthesis. The measured open-circuit voltage and entropic potential revealed that the same solid solution charging mechanism prevailed and was independent of particle size, as confirmed by in situ XRD measurements. In other words, particle size had no influence on the quasi-equilibrium thermodynamics behavior of Ti2Nb2O9. However, Ti2Nb2O9 electrodes made by sol-gel synthesis featured smaller overpotential and faster lithium diffusion. In fact, operando isothermal calorimetry revealed smaller instantaneous heat generation rates and smaller time-averaged irreversible heat generation rates at Ti2Nb2O9 electrodes made by sol-gel synthesis compared to those made by solid state synthesis at any given C-rate. These observations highlight the smaller resistive losses and the larger electrical conductivity of Ti2Nb2O9 synthesized by the sol-gel method. Furthermore, time-averaged reversible heat generation rates at Ti2Nb2O9 electrodes made by both synthesis methods featured significant contributions from entropic changes, ion adsorption/desorption, and ion solvation/desolvation accompanied by ion-pairing.
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Liu, Jay G., i David L. Wilcox. "Factors influencing the formation of hollow ceramic microspheres by water extraction of colloidal droplets". Journal of Materials Research 10, nr 1 (styczeń 1995): 84–94. http://dx.doi.org/10.1557/jmr.1995.0084.
Streszczenie:
Hollow ceramic microspheres of Al2O3, SiO2, and mullite have been prepared by the combination of an emulsion technique with a water extraction sol-gel method. Concentration of sol, initial droplet size, and water extraction rate of the system are found to be the important process parameters controlling the size and wall thickness of the hollow microspheres, and their influences are shown. A model that correlates the morphology of microspheres to concentration and water extraction rate is proposed and is in good agreement with the experimental observations. The capability and limitation of this process for forming hollow microspheres are demonstrated. It was shown that hollow microspheres with sizes greater than 5 μm could be readily prepared, while a limitation was met for sizes less than 1 μm, in which case solid microspheres were normally formed.
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Bischof, Grace, Brittney A. Cooper i John E. Moores. "A Record of Water-ice Clouds at the Phoenix Landing Site Derived from Modeling MET Temperature Data". Planetary Science Journal 3, nr 4 (1.04.2022): 97. http://dx.doi.org/10.3847/psj/ac649e.
Streszczenie:
Abstract Water-ice clouds were frequently detected throughout the 151-sol Phoenix mission by the Phoenix lidar, providing insight into the Martian water cycle. However, the lidar could not be used continuously, and as such, the cloud data were temporally constrained to when observations were acquired. Here we reconstruct a record of water-ice clouds at the Phoenix landing site by examining the radiative contribution made by the clouds to the surface energy balance. This is accomplished by modeling the data from the 2 m MET air temperature sensor on board the lander. Clouds radiating from 0 and 30 W m−2 of energy toward the surface are consistent with the MET record over the course of the mission. The additional longwave flux at the surface induced a warming of the surface and near-surface temperatures, usually between 1–3 K; however, the clouds showed a high degree of sol-to-sol variability. This radiative analysis indicates that clouds were present much earlier in the mission than previously known, and cloud emission reached a maximum near sol 90, consistent with analyses of the annular cloud at the Phoenix landing site. The modeled flux from clouds was compared to the water-ice optical depth retrieved from the Phoenix lidar, showing that optically thicker clouds emitted more radiation toward the surface.
49
Sanchez, Lloyd E., Shu‐Yau Wu i Ishver K. Naik. "Observations of ferroelectric polarization reversal in sol‐gel processed very thin lead‐zirconate‐titanate films". Applied Physics Letters 56, nr 24 (11.06.1990): 2399–401. http://dx.doi.org/10.1063/1.102891.
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Pang, Bo, David S. McPhail, Daniel Doni Jayaseelan i Aldo Roberto Boccaccini. "Development and Characterization of Transparent Glass Matrix Composites". Advances in Science and Technology 71 (październik 2010): 102–7. http://dx.doi.org/10.4028/www.scientific.net/ast.71.102.
Streszczenie:
Glass matrix composites based on NextelTM fibre reinforced borosilicate glass were fabricated. Unidirectional fibres were arranged in two directions with a periodic interspacing sandwiched between two glass slides. XRD analysis and SEM observations proved that the selected process parameters were effective in densifying the composites without significant transparency losses. A geometry based equation was derived to evaluate the expected light transmittance of the composites. ZrO2 coating on Nextel™ fibres, developed by a sol-gel method, was investigated in order to provide a weak bonding at the fibre/matrix interface to promote fibre pull-out during fracture. A developed hybrid sol-gel coating method was employed to form a smooth and crack free coating surface on the Nextel™ fibre bundles. The present composites show potential for applications in architecture and special machinery requiring strong transparent windows.