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Journal articles on the topic 'Compositeurs – Argentine'
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1
Cardoso, Thomas Fontes Saboga. "L’intervalle de quarte dans la musique d’Astor Piazzolla." Diacrítica 35, no. 2 (August 13, 2021): 43–65. http://dx.doi.org/10.21814/diacritica.637.
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Nous examinons dans cet article l’utilisation et l’origine de l’intervalle de quarte comme élément organisateur des hauteurs dans la musique du compositeur et bandonéoniste argentin Astor Piazzolla (1921–1992). Des exemples nous permettront de prendre contact avec une utilisation diversifiée de cet intervalle, soit mélodique ou harmonique, et d’en constater un emploi conscient et systématique. Une œuvre de jeunesse du compositeur où l’emploi de ces quartes est abondant nous permet de tisser un lien avec les leçons de Piazzolla avec Alberto Ginastera qui eurent lieu pendant l’élaboration de cette pièce, la musique de son professeur de cette période révélant elle-aussi d’importants usages de ces techniques quartales. Finalement, la fascination des deux compositeurs argentins pour Stravinski, et la présence de ces techniques quartales dans la musique du compositeur russe nous permet de déceler l’origine de ces techniques quartales dans la musique savante moderne.
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LIUT, MARTIN. "‘Devenir compositeur’: Notes on the Insertion of Argentine Composers in the Contemporary French Music Scene (1970–2000)." Twentieth-Century Music 17, no. 3 (October 2020): 311–27. http://dx.doi.org/10.1017/s1478572220000146.
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AbstractThis article studies a group of nineteen Argentinean composers who settled in Paris between 1970 and 2000. In addition to social and political factors of Argentine history – including the last military dictatorship (1976–83) and the 1989 period of ‘hyperinflation’ (1989) – these composers wanted to develop their careers in a professional field with the history, size, and diversity of Paris. Since the 1970s, France began a strong state policy supporting the arts; this action promoted a process of internationalization of Paris's artistic life. Contemporary music was viewed by participants and creators as an open and cosmopolitan space. Although the paradigm of autonomy suggests that nationality is less relevant than the individuality of each composer, the latter continues to function as an identity marker and, therefore, as a classification strategy both in France and in Argentina.
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Fontes Saboga Cardoso, Thomas. "L’incorporation d’éléments du jazz dans le tango d’Astor Piazzolla." Revue musicale OICRM 4, no. 2 (February 8, 2018): 118–35. http://dx.doi.org/10.7202/1043223ar.
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Nous examinons dans cet article la combinaison entre tango et jazz proposée par le compositeur et bandonéoniste argentin Astor Piazzolla (1921-1992). Les traits du tango y sont privilégiés, constituant les éléments de base repérables principalement dans des gestes mélodiques, des modèles d’accompagnement et des timbres caractéristiques très fréquemment employés, qui assurent aussi bien la cohésion et l’unité musicale que l’identité de ce genre urbain argentin, la centralité du tango figurant comme le principal moyen d’articuler ces univers. Nous observerons également une autre stratégie employée par le compositeur, consistant à profiter des caractéristiques communes des musiques métissées comme moyen pour atteindre l’alliance sonore – le métissage par intersection.
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Valverde, Gabriel. "Utopie et idéal dans la composition musicale aujourd’hui." Circuit 9, no. 1 (March 5, 2010): 7–16. http://dx.doi.org/10.7202/902213ar.
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Posant très haut la barre des idéaux qui devraient motiver le créateur d’aujourd’hui, le compositeur argentin Gabriel Valverde examine tour à tour les problèmes qui semblent motiver la démarche de bon nombre de créateurs : la notion de professionalisme, la quête du contrôle, les rapports de l’intensité et de l’intelligence, le fétichisme de la matière sonore.
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Carballo, Erick. "Alberto Ginastera: Le(s) style(s) d'un compositeur argentin (review)." Latin American Music Review 32, no. 1 (2011): 151–55. http://dx.doi.org/10.1353/lat.2011.0000.
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Jones, Pamela. "À la recherche des racines : la vie et la carrière d'alcides lanza en Argentine." Circuit 10, no. 2 (October 2, 2002): 9–16. http://dx.doi.org/10.7202/004676ar.
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Résumé L’auteur, musicologue, explore l’enfance et la jeunesse passées en Argentine, du compositeur alcides lanza et isole plusieurs événements qui auront une incidence marquée sur son oeuvre et ses choix futurs. Elle y voit l’origine de son talent inné pour le dessin et de sa passion pour le théâtre musical. Les principales étapes de sa formation théorique auprès de Julian Bautista à Rosario, puis à la Faculté de musique de l’institut Di Tella, à Buenos Aires, fondée par Alberto Ginastera, montrent que ses principales influences seront d’abord européennes puis, et surtout, américaines. Le vif intérêt de lanza pour la musique expérimentale le conduit rapidement vers l’électroacoustique. Quelques-unes des ses oeuvres sont brièvement décrites. Professeur à la Faculté de musique de l’université McGill, à Montréal, depuis 1971, lanza y a constamment encouragé le dialogue entre l’Amérique du Nord et l’Amérique latine.
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Erdmann, Eleonora, Marcos Lopes Dias, Victor Jayme Roget Rodriguez Pita, Fernanda Monasterio, Delicia Acosta, and Hugo Alberto Destéfanis. "Effect of the Organoclay Preparation on the Extent of the Intercalation/Exfoliation and the Barrier Properties in Polyamide-6/Montmorillonite Nanocomposites." Materials Science Forum 570 (February 2008): 78–84. http://dx.doi.org/10.4028/www.scientific.net/msf.570.78.
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This paper shows the importance of the clay surface chemistry in the preparation of nanocomposite materials. An Argentinean montmorillonite was used for preparing two modified clays. The filosilicate was intercalated with a quaternary ammonium salt derived from ε- caprolactam to obtain an organofilic material. The other modification was introduced by mixing the clay with hexadecyl trimethyl ammonium chloride. Thus, the polyamide 6 ability in dispersing clays was applied to prepare composites with the intercalated clays. The polyamide 6/clay dry composites with 3 wt % of filler were prepared by melt processing in a mixer chamber. Composites of polyamide 6/organoclay were characterized by X-ray diffraction, transmission and scanning electron microscopy and thermogravimetry. The barrier properties were determined by cyclohexane pervaporation. The results show that the dispersion and degree of delamination depend on a proper chemical treatment and the clay content influences the polyamide 6 nanocomposites solvent pervaporation resistance.
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Grilli, Mariano P., and David E. Gorla. "The spatio-temporal pattern of Delphacodes kuscheli (Homoptera: Delphacidae) abundance in central Argentina." Bulletin of Entomological Research 87, no. 1 (February 1997): 45–53. http://dx.doi.org/10.1017/s0007485300036348.
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AbstractDelphacodes kuscheli Fennah is the vector of maize rough dwarf virus, that affects maize production in central Argentina. The spatial and temporal abundance pattern of the insect vector was studied from October 1992 to November 1994, within endemic and non-endemic areas of the crop disease. Insect density was estimated every 7–15 days during spring and summer (maize season) or monthly during autumn and winter from high (6 m) and low (1.5 m) sticky traps placed at eight sampling stations along a 300 km transect. Each year, D. kuscheli density increased from October, peaked in December, to decrease afterwards and disappear in May. Density was lower in the nonendemic area and higher in the endemic one. The average absolute difference of density between sampling station pairs increased with the distance between the sampling stations (R2=0.85), and the correlation of density changes decreased with the distance between the sampling stations (R2=0.78), suggesting that the population dynamics were affected more by local than by regional factors. There was a significant correlation (with a 36 days lag) between the normalized difference vegetation index (NDVI) (calculated from 15 days maximum value composites images of NOAA-11 meteorological satellites) and D. kuscheli abundance. Based on this regression model, and using the time series of the satellite derived NDVI values, maps of the distribution and abundance of D. kuscheli within the study area for the spring and summer of 1992 were produced.
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Caragunis, JI, JA Rivera, and OC Penalba. "Characterisation of hydrological droughts in centralnorth Argentina and their atmospheric and oceanic drivers." Climate Research 80, no. 1 (April 9, 2020): 1–18. http://dx.doi.org/10.3354/cr01593.
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Low streamflows caused by natural and anthropogenic forcings affect ecosystems and societies, especially on large timescales. We analysed the main basins of central-north Argentina (CNA) using centennial streamflow data. This study is focussed on describing spatial and temporal variability of hydrological drought events, and evaluating the atmospheric and oceanic drivers under hydrological drought conditions. The Standardized Streamflow Index in the period 1919-2014 was applied, sectored by 4 major basins. The western Argentinian rivers (Colorado Basin, CB) have shown increasing drought events since the 1940 decade, while in the east, a sharp decrease occurred from 1970 onwards. Extreme drought events occurred over CB and La Plata Basin (LPB) during the periods 1966-1972 and 2010-2014. Atmospheric and oceanic patterns under hydrological drought conditions show anticyclonic anomalies over the South Pacific Ocean (SPO), cyclonic sub-polar anomalies and La Niña-like conditions with warm sea surface temperature anomalies (SSTAs) in SPO for the western basins. Over LPB, a strong cold SSTA in the tropical south-western Atlantic Ocean is positioned in phase with the cyclonic anomalies. At mid-latitudes, a warm SSTA and anticyclonic anomalies are detected. Water vapour transport composites show southerly winds and drier conditions for northern and eastern Argentina, and weakening of westerly winds with drier atmosphere for western rivers. These results deepen our knowledge of natural forcings related to hydrological drought events in CNA and in the predictability of such complex natural hazards.
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Foletto, E. L., C. Volzone, A. F. Morgado, and L. M. Porto. "Influência do tipo de ácido usado e da sua concentração na ativação de uma argila bentonítica." Cerâmica 47, no. 304 (December 2001): 208–11. http://dx.doi.org/10.1590/s0366-69132001000400008.
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A ativação ácida de uma argila tem por finalidade aumentar as suas propriedades adsortivas e catalíticas. Nesse estudo, uma amostra de argila bentonítica, proveniente da Província de Mendoza (Argentina), foi ativada com diferentes concentrações (4 e 8 N) por ácido sulfúrico e clorídrico. Para verificar a influência das concentrações e do tipo de ácido usado na ativação da argila, utilizou-se técnicas de difração de raios X, análise térmica diferencial e termogravimétrica e análise química. Os resultados mostraram que houve modificação na estrutura do material argiloso após o ataque ácido. O tratamento com ácido sulfúrico e clorídrico sobre uma mesma bentonita originou produtos com diferentes características estruturais.
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Conconi, M. S., M. Morosi, J. Maggi, P. E. Zalba, F. Cravero, and N. M. Rendtorff. "Thermal behavior (TG-DTA-TMA), sintering and properties of a kaolinitic clay from Buenos Aires Province, Argentina." Cerâmica 65, no. 374 (June 2019): 227–35. http://dx.doi.org/10.1590/0366-69132019653742621.
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Abstract The technological properties of a local kaolin, considered as a potential industrial material, were correlated with the thermal behavior and sintering processes carried out through a series of thermochemical analyses. The chemical and mineralogical characterization of the material was carried out, together with a simple microstructural characterization. The used material corresponded to the kaolinized basement rocks (saprolite zone) mined at La Verónica quarry, Chillar area, Azul County, Argentina. The complete kaolinite-metakaolinite-spinel-mullite thermal series was characterized. Sintering behavior was studied; a viscous phase sintering mechanism was proposed. Apparent density and porosity of fired ceramics were measured. A light-firing color was confirmed by colorimetry. The viscous phase mechanism was possibly described thanks to the multi-technique thermal behavior analysis complemented by XRD analysis. These results permitted to establish formulation and processing strategies of ceramic materials based on the studied clay. The possible applications include: tile manufacturing, sanitary ware, tableware, kaolinitic proppants, chamotte and refractory materials.
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Lorenz, Melanie, Uwe Altenberger, Robert B. Trumbull, Raúl Lira, Mónica López de Luchi, Christina Günter, and Sascha Eidner. "Chemical and textural relations of britholite- and apatite-group minerals from hydrothermal REE mineralization at the Rodeo de los Molles deposit, Central Argentina." American Mineralogist 104, no. 12 (December 1, 2019): 1840–50. http://dx.doi.org/10.2138/am-2019-6969.
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Abstract Britholite group minerals (REE,Ca)5[(Si,P)O4]3(OH,F) are widespread rare-earth minerals in alkaline rocks and their associated metasomatic zones, where they usually are minor accessory phases. An exception is the REE deposit Rodeo de los Molles, Central Argentina, where fluorbritholite-(Ce) (FBri) is the main carrier of REE and is closely intergrown with fluorapatite (FAp). These minerals reach an abundance of locally up to 75 modal% (FBri) and 20 modal% (FAp) in the vein mineralizations. The Rodeo de los Molles deposit is hosted by a fenitized monzogranite of the Middle Devonian Las Chacras-Potrerillos batholith. The REE mineralization consists of fluorbritholite-(Ce), britholite-(Ce), fluorapatite, allanite-(Ce), and REE fluorcarbonates, and is associated with hydrothermal fluorite, quartz, albite, zircon, and titanite. The REE assemblage takes two forms: irregular patchy shaped REE-rich composites and discrete cross-cutting veins. The irregular composites are more common, but here fluorbritholite-(Ce) is mostly replaced by REE carbonates. The vein mineralization has more abundant and better-preserved britholite phases. The majority of britholite grains at Rodeo de los Molles are hydrothermally altered, and alteration is strongly enhanced by metamictization, which is indicated by darkening of the mineral, loss of birefringence, porosity, and volume changes leading to polygonal cracks in and around altered grains. A detailed electron microprobe study of apatite-britholite minerals from Rodeo de los Molles revealed compositional variations in fluorapatite and fluorbritholite-(Ce) consistent with the coupled substitution of REE3+ + Si4+ = Ca2+ + P5+ and a compositional gap of ~4 apfu between the two phases, which we interpret as a miscibility gap. Micrometer-scale intergrowths of fluorapatite in fluorbritholite-(Ce) minerals and vice versa are chemically characterized here for the first time and interpreted as exsolution textures that formed during cooling below the proposed solvus.
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Volzone, C., and L. B. Garrido. "Retention of chromium by modified Al-Bentonite." Cerâmica 48, no. 307 (September 2002): 153–56. http://dx.doi.org/10.1590/s0366-69132002000300008.
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Retention of chromium (III) from a tanning wastewater by modified Al-bentonites was studied. One bentonite from San Juan province, Argentina, was used. Al-bentonite was prepared by contact of bentonite with hydrolyzed OH-Al solutions (0.10 M in Al) for 24 hours. The modified Al-bentonites were obtained by: a) treatment with 0.5 M sodium chloride; b) with 0.5 M sodium chloride adjusted at pH 8; and c) treatment with an hexametaphosphate solution after sodium addition. Then, the samples were dried at 100 °C and heated at 500 °C. The chromium (III) retention by samples was carried out in batch system putting in contact the material with a 2000 ppm Cr tannery waste at different times. The retained chromium was characterized by analyzing the supernatant using UV-visible spectroscopy. The different chromium retention was correlated with structural characteristics of the solids.
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Fachinotti, Victor D., Facundo Bre, Christoph Mankel, Eduardus A. B. Koenders, and Antonio Caggiano. "Optimization of Multilayered Walls for Building Envelopes Including PCM-Based Composites." Materials 13, no. 12 (June 20, 2020): 2787. http://dx.doi.org/10.3390/ma13122787.
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This work proposes a numerical procedure to simulate and optimize the thermal response of a multilayered wallboard system for building envelopes, where each layer can be possibly made of Phase Change Materials (PCM)-based composites to take advantage of their Thermal-Energy Storage (TES) capacity. The simulation step consists in solving the transient heat conduction equation across the whole wallboard using the enthalpy-based finite element method. The weather is described in detail by the Typical Meteorological Year (TMY) of the building location. Taking the TMY as well as the wall azimuth as inputs, EnergyPlusTM is used to define the convective boundary conditions at the external surface of the wall. For each layer, the material is chosen from a predefined vade mecum, including several PCM-based composites developed at the Institut für Werkstoffe im Bauwesen of TU Darmstadt together with standard insulating materials (i.e., EPS or Rockwool). Finally, the optimization step consists in using genetic algorithms to determine the stacking sequence of materials across the wallboard to minimize the undesired heat loads. The current simulation-based optimization procedure is applied to the design of envelopes for minimal undesired heat losses and gains in two locations with considerably different weather conditions, viz. Sauce Viejo in Argentina and Frankfurt in Germany. In general, for each location and all the considered orientations (north, east, south and west), optimal results consist of EPS walls containing a thin layer made of the PCM-based composite with highest TES capacity, placed near the middle of the wall and closer to the internal surface.
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Arraut, J. M., and H. M. J. Barbosa. "Large scale features associated with strong frontogenesis in equivalent potential temperature in the South American subtropics east of the Andes." Advances in Geosciences 22 (October 13, 2009): 73–78. http://dx.doi.org/10.5194/adgeo-22-73-2009.
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Abstract. South American subtropics east of the Andes exhibit a region of intense climatological frontogenesis in equivalent potential temperature (EPT) in the December to March season, mostly produced by deformation of the wind field. The goal of this paper is to investigate the large scale features associated with intense and weak frontogenesis by deformation (FGD) in EPT in the region where it attains its climatological maximum. This can be approximately delimited by 32–42° S and 66–69° W, which is small enough as to contain only one synoptic perturbation at a time. The spatial average of the positive values of frontogenesis at 850 hPa over the whole region (DFG+) is used to represent the strength of the perturbation. ECMWF ERA-40 reanalysis data set is used to calculate DFG+ at six hour intervals for 21 seasons (1981–2002). Compositing analysis is carried out for strong (above the 0.75 quantile) and weak (below the 0.25 quantile) events. For strong events the geopotential field at 850 hPa exhibits the North Argentinean Low (NAL), a transient trough and the Low Pressure Tongue East of the Andes (LPT). Upon comparison with the composite field of FGD it can be observed that FGD exhibits a strong maximum over the Argentinean Col (AC) which separates the NAL and the trough. These features are absent in the weak frontogenesis composite, which exhibits a stronger South Pacific Subtropical High close to the continent. At 250 hPa the strong FGD composite exhibits a trough over the Andes with a wind speed maximum to its east. Both of these features are associated with the deepening of the NAL in the literature. These are not present in the weak FGD composites. Strong events show an intense quasi meridional corridor of water vapor transport from the Amazon to the subtropics that encounters westerly flow in the neighborhood of the AC. This is absent in weak events. A preliminary analysis of precipitation is carried out using the GPCP daily data set. An intense precipitation nucleus appears slightly northeast of the AC, with maximum intensity in the day that follows the strong events. Weak events exhibit a drying of the subtropics instead, between one and three days after the events. Higher precipitation over the oceanic South Atlantic Convergence Zone can be also observed. Analogous composites were constructed for the presence and absence of both the AC and the LPT, showing similar characteristics to the strong and weak FGD event composites respectively, but with lower intensities. This shows that by selecting strong FGD events, intense NAL and LPT events are also singled out.
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Silva, G. A. M., and T. Ambrizzi. "Inter-El Niño variability and its impact on the South American low-level jet east of the Andes during austral summer − two case studies." Advances in Geosciences 6 (March 8, 2006): 283–87. http://dx.doi.org/10.5194/adgeo-6-283-2006.
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Abstract. The impact of the maximum convection location over eastern and central Equatorial Pacific over the intensity and positioning of the South American Low-Level Jet east of the Andes (SALLJ) during the austral summer was investigated. The Bonner criteria 1 was applied to the NCEP-NCAR circulation fields during the El Niño of 1997/1998 and 2002/2003 to identify the SALLJ episodes. The composites of the atmospheric circulation over the South America during El Niño events showed that the SALLJ can be influenced by small displacements of the quasi-stationary Rossby waves position. During the strong El Niño event of 1997/1998 the SALLJ is maintained by the eastern trade winds. A low-level anomalous anticyclonic circulation over the central part of Brazil enhanced the wind in the nucleus of the jet and displaced its axis to the Northern Argentina and South of Brazil. However, the northern trade winds seem to maintain the SALLJ during the weak El Niño of 2002/2003. The jet was weaker and displaced more southeastward of Brazil than during the strong event.
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Wilson, Ian Richard. "The constitution, evaluation and ceramic properties of ball clays." Cerâmica 44, no. 287-288 (August 1998): 88–117. http://dx.doi.org/10.1590/s0366-69131998000400002.
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Ball clay is a fine-grained highly plastic, mainly kaolinitic, sedimentary clay, the higher grades of which fire to a white or near white colour. The paper will review the origin of the term "Ball Clay" and the location and origins of several deposits with particular emphasis on the mineralogical, physical and rheological properties which make the clays so important in ceramics bodies. Particular attention will be paid to the well known bay clay deposits of Devon and Dorset in southwest England, which are mined by ECC International Europe and Watts Blake Bearne & Company PLC, and brief descriptions from elsewhere in the world of ball clays from the United States, Germany, Czech Republic, Thailand, Indonesia, Argentina and China. The evaluation of deposits will be covered along with a description of the main types of ball clay for ceramics with details of the mining, processing and blending techniques which are necessary to ensure long term consistency of products. A brief description in given of the ceramic properties of some Brazilian ball clays. The location of some ball clay deposits is shown in Fig. 1.
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Castrillo, N., A. Mercado, and C. Volzone. "Solid desiccants from natural and modified bentonites." Cerâmica 64, no. 372 (December 2018): 526–37. http://dx.doi.org/10.1590/0366-69132018643722447.
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Abstract The aim of the present work was to study Argentinean natural clays with different modifications and their use as desiccants. To this end, bentonite clays collected from different regions were characterized and modified by heat treatment and calcium addition, and the desiccant capacity, in the form of powder and pellets, was studied. In addition, the hydration degree reversibility of these materials was estimated. The mineralogical and structural characterization was performed by X-ray diffraction, Fourier-transform infrared spectroscopy, differential thermal analysis, and thermogravimetric analysis. The textural characterization was performed by adsorption-desorption of N2, chemical composition by X-ray fluorescence and cation exchange capacity. The water adsorption was determined at 25 °C between 11-98% relative humidity. The results indicated that the desiccant power has a close relationship with the degree of clay purity, drying of the sample and the method of calcium incorporation.
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Boers, Niklas, Henrique M. J. Barbosa, Bodo Bookhagen, José A. Marengo, Norbert Marwan, and Jürgen Kurths. "Propagation of Strong Rainfall Events from Southeastern South America to the Central Andes." Journal of Climate 28, no. 19 (September 29, 2015): 7641–58. http://dx.doi.org/10.1175/jcli-d-15-0137.1.
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Abstract Based on high-spatiotemporal-resolution data, the authors perform a climatological study of strong rainfall events propagating from southeastern South America to the eastern slopes of the central Andes during the monsoon season. These events account for up to 70% of total seasonal rainfall in these areas. They are of societal relevance because of associated natural hazards in the form of floods and landslides, and they form an intriguing climatic phenomenon, because they propagate against the direction of the low-level moisture flow from the tropics. The responsible synoptic mechanism is analyzed using suitable composites of the relevant atmospheric variables with high temporal resolution. The results suggest that the low-level inflow from the tropics, while important for maintaining sufficient moisture in the area of rainfall, does not initiate the formation of rainfall clusters. Instead, alternating low and high pressure anomalies in midlatitudes, which are associated with an eastward-moving Rossby wave train, in combination with the northwestern Argentinean low, create favorable pressure and wind conditions for frontogenesis and subsequent precipitation events propagating from southeastern South America toward the Bolivian Andes.
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Satyamurty, Prakki, Serafim Barbosa De Sousa Jr, Mateus Da Silva Teixeira, and Lucia Eliane Maria Gularte Da Silva. "Regional circulation differences between a rainy episode and a nonrainy episode in eastern São Paulo State in March 2006." Revista Brasileira de Meteorologia 23, no. 4 (December 2008): 404–16. http://dx.doi.org/10.1590/s0102-77862008000400003.
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The differences between the regional flow characteristics of a rainy episode and a nonrainy episode in March 2006 in eastern São Paulo state are discussed. The surface humidity and temperature characteristics do not show significant differences between the two cases. The composites of the middle tropospheric geopotential field and the lower-tropospheric wind field show a short-wave trough in the Atlantic off southern Brazil during the rainy episode. In the upper troposphere, the Bolivian high is stronger during the rainy episode than during the nonrainy episode, indicating that the troposphere over tropical South America is warmer during the rainy episode. The low-level jet in the rainy case does not penetrate northern Argentina, and is more NW-SE oriented, indicating that the humidity transport is more toward the southeastern Brazil. The moisture flux convergence over the eastern São Paulo at the 850-hPa is fairly strong in the rainy case whereas it is divergent in the nonrainy case. The presence of a low pressure area in the South Atlantic with westward tilt in the vertical provides synoptic forcing for the rising motion over eastern São Paulo state. These differences seem to be useful indicators for distinguishing rainy and nonrainy episodes.
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Müller, Gabriela V., and Guillermo J. Berri. "Atmospheric Circulation Associated with Persistent Generalized Frosts in Central-Southern South America." Monthly Weather Review 135, no. 4 (April 1, 2007): 1268–89. http://dx.doi.org/10.1175/mwr3344.1.
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Abstract This paper describes the large-scale atmospheric circulation associated with persistent generalized frosts (GFs; at least 75% of the stations report frosts) in the east-central region of Argentina known as the Wet Pampa. The GF events are grouped according to their persistence, and NCEP–NCAR reanalysis data are used to create daily composites of mass and wind field anomalies during the 1961–90 winters. The GFs are caused by an anticyclonic anomaly that enters South America, generating southerly wind anomalies and cold air advection that are strengthened by the meridional layout of a cyclonic anomaly over the South Atlantic Ocean. In the case of the more persistent events the wind anomaly grows during the previous days and becomes quasi-stationary. Also, the study identifies at 250 hPa a double train of eastward-moving Rossby waves along the subtropical and subpolar latitudes, respectively, of the Southern Hemisphere. The layout of both wave trains favors the development of an intense southerly wind anomaly in the entire southern cone of the continent. On the other hand, the propagation pattern during the less persistent GFs shows only one arc-shaped Rossby wave train that reaches South America, and then propagates northeastward. Additionally, there is a subtropical jet entrance/confluence over the western side of the continent that induces a secondary meridional circulation whose subsiding branch facilitates the equatorward displacement of the low-level anticyclone, particularly in the case of the less persistent events. In the case of the more persistent GFs the confluence is located farther east and sustains essentially zonal wave train propagation, so that the surface anticyclone is not able to achieve a major equatorward penetration.
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Weske, Sebastian, Richard A. Hardin, Thomas Auth, Richard A. J. O’Hair, Konrad Koszinowski, and Craig A. Ogle. "Argentate(i) and (iii) complexes as intermediates in silver-mediated cross-coupling reactions." Chemical Communications 54, no. 40 (2018): 5086–89. http://dx.doi.org/10.1039/c8cc01707g.
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Silver-mediated cross-coupling reactions proceed via anionic ate complexes, which have been characterized by a combination of NMR spectroscopy, ESI mass spectrometry, and quantum-chemical calculations.
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Müller, G. V., T. Ambrizzi, and S. E. Ferraz. "The role of the observed tropical convection in the generation of frost events in the southern cone of South America." Annales Geophysicae 26, no. 6 (June 11, 2008): 1379–90. http://dx.doi.org/10.5194/angeo-26-1379-2008.
Full textAbstract:
Abstract. Based on previous results obtained from observations and linear wave theory analysis, the hypothesis that large-scale patterns can generate extreme cold events in southeast South America through the propagation of remotely excited Rossby waves was already suggested. This work will confirm these findings and extend their analysis through a series of numerical experiments using a primitive equation model where waves are excited by a thermal forcing situated in positions chosen according to observed convection anomalies over the equatorial region. The basic state used for these experiments is a composite of austral winters with maximum and minimum frequency of occurrence of generalized frosts that can affect a large area known as the Wet Pampas located in the central and eastern part of Argentina. The results suggest that stationary Rossby waves may be one important mechanism linking anomalous tropical convection with the extreme cold events in the Wet Pampas. The combination of tropical convection and a specific basic state can generate the right environment to guide the Rossby waves trigged by the tropical forcing towards South America. Depending on the phase of the waves entering the South American continent, they can favour the advection of anomalous wind at low levels from the south carrying cold and dry air over the whole southern extreme of the continent, producing a generalized frost in the Wet Pampa region. On the other hand, when a basic state based on the composites of minimum frosts is used, an anomalous anticyclone over the southern part of the continent generates a circulation with a south-southeast wind which brings maritime air and therefore humidity over the Wet Pampas region, creating negative temperature anomalies only over the northeastern part of the region. Under these conditions even if frosts occur they would not be generalized, as observed for the other basic state with maximum frequency of occurrence of generalized frosts.