Setting research priorities for preconception care in low- and middle-income countries: aiming to reduce maternal and child mortality and morbidity Dean, Sohni; Rudan, Igor; Althabe, Fernando; Webb Girard, Aimee; Howson, Christopher; Langer, Ana; Lawn, Joy; Reeve, Mary Elizabeth; Teela, Katherine C.; Toledano, Mireille; Venkjatraman, Chandra Mouli; Belizan, Jose; Car, Josip; Chan, Kit Yee; Chatterjee, Subidita; Chitekwe, Stanley; Doherty, Tanya; Donnay, France; Ezzati, Majid; Humayun, Khadija; Jack, Brian; Lassi, Zohra S.; Martorelli, Reynaldo; Poortman, Ysbrand; Bhutta, Zulfiqar A. Preconception care means providing care before pregnancy is established. Women and couples of reproductive age are generally unaware of the effects that their own health conditions and health-related behaviors may have on the fetus during pregnancy. Although antenatal care is set in the maternal, newborn, and child health (MNCH) continuum [1], it neglects the most critical time of embryonic development, which often occurs before a woman even knows she is pregnant [2]. The evidence increasingly points to earlier care before pregnancy to improve women´s health, and better pregnancy outcomes for the mother and newborn.

Characterization of the atmospheric depth profile using the ground-level temperature: The case of Malargüe, Argentina Moreno, Juan Cruz; Sciutto, Sergio Juan We present a study of the atmospheric depth profile and the dependence with its characteristic parameters. We introduce a new model, named GAMMA, based on a parameterization that allows us to obtain the atmospheric depth profile specifying only one simple physical parameter, namely the temperature at ground. The GAMMA model consists of a multilayer representation of the atmosphere that can be adjusted conveniently via constrained fits that are built to ensure interlayer continuity for both atmospheric depth and density profiles. Our analysis uses experimental data collected at Malargüe, Argentina by meteorological radiosondes. The GAMMA model can reproduce the averaged atmospheric depth profiles in all the cases available for analysis with good accuracy. The relative differences between model predictions and averaged data are always less than approximately 0.7%.

Seasonal variation in genetic population structure of sábalo (Prochilodus lineatus) in the Lower Uruguay River Rueda, Eva Carolina; Carriquiriborde, Pedro; Monzón, Alexander; Somoza, Gustavo Manuel; Ortí, Guillermo Prochilodus lineatus is a highly migratory fish species that sustains the most important commercial fishery of Parana-Paraguay basin. Migratory patterns are poorly known and only few population genetic studies are avaliable for this species in the Upper Parana. To assess genetic population structure, we genotyped a sample of 93 individuals from the Lower Uruguay River close to Gualeguaychu city (Entre Rıos, Argentina) at three different times, July 2008 (Winter), September 2008 (Spring) and May 2009 (Fall). All individuals were genotyped for 12microsatellite loci previously found to be informative to assess populations of P. lineatus. Our results show seasonal variation of the genetic sub-structuring at this locality that may be related to the presence of different migratory stocks throughout the year. The Fall sample includes an additional genetic cluster of individuals not detected in Winter and Spring, suggesting that this species should be considered a mixed stock fishery.

Integrated ecotoxicological assessment of bottom sediments from the Paraná basin, Argentina Peluso, María Leticia; Abelando, Mariana; Apartin, Carina Diana; Almada, Pablo; Ronco, Alicia Estela Paraná River, the six largest in the world, is receptor of pollution loads from tributaries traversing urban and industrialized areas, and extensive agriculture, particularly in its middle and low stretch along the Argentinean sector, where most of the productive activities of the country develop. Within the frame of monitoring surveys, the quality of bottom sediments from distal positions of twenty tributaries and three of the main course was evaluated. The assessment covered testing lethal and sublethal effects with the Hyalella curvispina based toxicity test, a benthic macrofauna survey and physicochemical variables of sediment matrix composition. A multivariate statistical analysis approach permitted integrating the obtained data from the different survey lines of evidence, explaining potential causes of the measured biological effects. The main perturbations detected were associated to tributaries in the middle sector of the basin, where anoxic conditions with high sulfide contents prevail mostly related to organic matter inputs of diverse combined activities, where sediments induce high lethality, and a consequent strong reduction of the benthic community population and diversity. The integrated survey approach proved being a robust tool in the assessment of causative—adverse effects relationships.

Thermotropic mesomorphism of mixed-valent diruthenium aliphatic carboxylates with axial anion bearing two aliphatic chains Bottazzi, Tamara Paula; Cecchi, Florencia; Zelcer, Andrés; Benoit, Heinrich; Donnio, Bertrand; Guillon, Daniel; Cukiernik, Fabio Daniel A homologous series of binuclear mixed-valent diruthenium tetracarboxylates, Ru2(O2C(CH2)n-2CH3)DHDP, (DHDP=di(hexadecyl)phosphate axial anion, n=10,12,14,16 and 18), have been synthesized and characterized, and liquid crystallines properties of these compounds were examined. All the compounds exhibit a room-temperature crystallines lamellar phase and a high temperature (above 140º) Col_h mesophase. Another, probably semi-crustallines lamellar intermediate phase has also been found for all the studied compounds but for the n=18 derivative. Comparison with related mesogenic homologous series where the equatorial ligands are alsolinear carboxylates, but the axial anion bear just one aliphatic chain (carboxylates, octylslfonate, and dodecylsulfate), shows that the presence of a second aliphatic chain in the axial anion both lowers the transition temperatures and modifies the nature of the intermediate lamellar phase. Structural models at the molecular level are suggested for the crystallines lamellar en the Col_h phases.

Andean cat in northern Patagonia: linking conservation and research Palacios, Rocio

Postcranial anatomy and phylogenetic relationships of Mussaurus patagonicus (Dinosauria, Sauropodomorpha) Otero, Alejandro; Pol, Diego The transition from basal sauropodomorphs to sauropods is one of the most dramatic evolutionary transformations in the history of dinosaurs. Constituent taxa of this transition were recorded mainly in South Africa and South America, and to a lesser extent in North America. We describe here the postcranial anatomy of four specimens of basal sauropodomorphs from the Late Triassic of Patagonia, Argentina, and identify them as adult individuals of Mussaurus patagonicus. The material is composed of one subadult and three adult specimens and was originally identified as Plateosaurus. The completeness of the material provides more complete knowledge of this taxon and allows us to introduce aspects of basal sauropodomorph anatomy that were poorly understood until now, such as the configuration and arrangement of the distal carpal elements. The phylogenetic relationships of Mussaurus patagonicus are tested through a cladistic analysis of basal sauropodomorphs based on the anatomy of these specimens rather than on the post-hatchling and juvenile specimens previously known for this taxon. Mussaurus is recovered as a non-sauropod anchisaurian, being the sister group of Aardonyx plus more derived sauropodomorphs and is depicted outside the ‘quadrupedal clade,’ given the presence of plesiomorphic features such as a humerus/femur ratio <0.8, a curved femoral shaft in lateral view, and a nearly circular femoral midshaft cross-section. Mussaurus patagonicus adds new and valuable information that helps to clarify the core of the basal sauropodomorph-sauropod transition.

Future changes in drought characteristics over southern South America projected by a CMIP5 multi-model ensemble Penalba, Olga Clorinda; Rivera, Juan Antonio The impact of climate change on drought main characteristics was assessed over Southern South America. This was done through the precipitation outputs from a multi-model ensemble of 15 climate models of the Coupled Model Intercomparison Project Phase 5 (CMIP5). The Standardized Precipitation Index was used as a drought indicator, given its temporal flexibility and simplicity. Changes in drought characteristics were identified by the difference for early (2011-2040) and late (2071-2100) 21st century values with respect to the 1979-2008 baseline. In order to evaluate the multi-model outputs, model biases were identified through a comparison with the drought characteristics from the Global Precipitation Climatology Centre database for the baseline period. Future climate projections under moderate and high-emission scenarios showed that the occurrence of short-term and long-term droughts will be more frequent in the 21st century, with shorter durations and greater severities over much of the study area. These changes in drought characteristics are independent on the scenario considered, since no significant differences were observed on drought changes. The future changes scenario might be even more dramatic, taking into account that in most of the region the multi-model ensemble tends to produce less number of droughts, with higher duration and lower severity. Therefore, drought contingency plans should take these results into account in order to alleviate future water shortages that can have significant economic losses in the agricultural and water resources sectors of Southern South America.

Constructivismo y sociología: siete tesis de Bruno Latour; Constructivism and sociology: seven theses of Bruno Latour de Grande, Pablo Ernesto Bruno Latour postula que la sociología contemporánea se dedica en buena medida a explicar cómo ciertas configuraciones sociales (tales que las jerarquías de poder o las desigualdades estructurales) afectan el funcionamiento de otros ámbitos en sus contenidos no sociales (tales que el derecho, la religión o el arte). Como consecuencia de esto, la misma habría abandonado su misión primaria de explicar lo social por sí mismo, además de estar produciendo explicaciones repetitivas y poco interesantes. El presente artículo reúne elementos teóricos de diferentes obras de Bruno Latour en función de elaborar siete tesis sobre su crítica radical a la sociología contemporánea. La propuesta principal de Latour es reformular la investigación social, abriendo la ‘caja negra' en la que lo social ha venido a convertirse. Finalmente se realizan algunas consideraciones sobre usos y limitaciones de las posiciones de Bruno Latour.; Bruno Latour argues that contemporary sociology is largely devoted to explain how certain social configurations (such as power hierarchies or structural inequalities) affect other non-social activities (such as law, religion or arts). As a result, sociology would have had abandoned its primary mission to explain the social itself, and it would be producing repetitive and uninteresting explanations. This paper puts together theoretical elements from different works of Bruno Latour in order to state seven theses on his radical critique to contemporary sociology. The main goal of Latour's proposal is reformulating social research, opening the black box in which the Social would have become. Finally, the article concludes summarizing usages and limitations of the perspective of Bruno Latour.

Fabricación de estándares de calibración para microsondas nucleares; Calibration standars of nuclear microprobes Arena, S.; Faya, T.; Lell, J.; Vega, N.; Davidson, Jorge; Nesprias, Francisco Jose Gabriel; Debray, M. El Micro-haz de iones Pesados (MiP) del laboratorio Tandar constituye un instrumento de características únicas en el país, pues puede proveer haces de iones pesados de dimensiones micrométricas acelerados hasta decenas de MeV de energía. La búsqueda de tamaños de haz más pequeños ha creado la necesidad de contar con estándares de calibración de elevada calidad de resolución. En el presente trabajo se desarrollaron los primeros prototipos para calibrar la focalización del haz: estructuras metálicas de cobre o niquel en forma de grilla con orificios cuadrados. Se emplearon dos métodos de fabricación. En el primero se utilizaron técnicas de fotolitografía convencional sobre un sustrato de silicio con foto-resina, mientras que en el segundo se utilizó el MiP para micro-mecanizar sustratos de Niobato de Litio (LiNbO3). En ambos casos se finalizó el proceso de fabricación del patrón con electrodeposición de cobre o níquel sobre la matriz desarrollada. Mediante la técnica fotolitográfica se fabricaron grillas de níquel que varían entre 130 y 180 mesh**. Mediante micro-mecanizado con el MiP se fabricaron grillas de cobre de entre 500 y 2000 mesh sobre sustratos de LiNbO3.; The Micro-heavy ion beam (MiP) at Tandar’s Lab is a unique instrument in the country, as it can provide heavy ion beams at micrometer-scale accelerated to tens of MeV energy. The quest for smaller beam sizes has created the need for calibration standards of high resolution quality. In this paper we developed the first prototypes to calibrate the beam focusing: metal structures of copper or nickel shaped grid with square holes. We used two methods of manufacture. Were used in the first conventional photolithography techniques on a silicon substrate with photoresin while the second was used for micromachining with MiP substrates of lithium niobate (LiNbO3). In both cases the process for the manufacture was finished with electro-deposition of copper or nickel on the matrix developed. By photolithographic technique nickel grids were manufactured varying between 130 and 180 mesh. By MiP micromachining copper grids were produced between 500 and 2000 mesh on LiNbO3 substrates.

El uso de zonas censales para medir la segregación residencial: contraindicaciones, propuesta metodológica y un estudio de caso: Argentina 1991-2001 Rodriguez, Gonzalo Martin Medir la segregación residencial a partir de unidades espaciales arbitrarias construidas por los organismos censales conlleva ciertos inconvenientes vinculados a lo que se conoce como el Problema de la Unidad Espacial Modificable (PUEM). Este problema ha sido generalmente ignorado por la mayoría de los investigadores, como si no afectara los resultados de sus estudios. En este trabajo se discute la legitimidad de usar zonificaciones censales para medir la segregación residencial, y se propone el uso de técnicas de desagregación y reagrupamiento de datos (DRD) que podrían aportar a reducir los sesgos del PUEM. Una de estas técnicas es utilizada para medir la segregación residencial socioeconómica en la Argentina durante el período 1991-2001. Se concluye que en países como Argentina estas técnicas constituyen, sin embargo, una solución muy limitada, y que solo a partir de introducir cambios de política en la gestión de datos censales podrá mejorarse sustancialmente la calidad de los estudios en este y otros campos.; Attempts on measuring residential segregation using arbitrary spatial units constructed by census agencies carry certain drawbacks related to what is commonly known as the Modifiable Areal Unit Problem (MAUP). This problem has been generally ignored by urban researchers in this topic as if it would not affect the results of their studies. This paper discusses the legitimacy of using census zoning systems for measuring residential segregation, and proposes the use of data disaggregation and regrouping (DDR) techniques that may at some degree contribute in reducing MAUP biases. One of these techniques is used for measuring socioeconomic residential segregation trends in Argentina for the 1991-2001 period. We conclude that in countries like Argentina these techniques represent just a partial and limited solution to MAUP. Quality and precision of quantitative studies on residential segregation and other fields dealing with similar problems may be substantially improved only if better access to spatially disaggregated data is provided by census agencies.

Los procesos subjetivos en las reformas de las carreras universitarias Colella, Leonardo Javier El artículo plantea la temática de la reproducción de la desigualdad a través de las instituciones educativas y problematiza las prácticas de dominios que desbordan la cuestión del contenido curricular. La problematización se sitúa en el contexto de las reformas de las carreras universitarias en la actualidad.

Foucault y Rancière como educadores: la explicación como técnica de sí mismo Colella, Leonardo Javier La intención de este artículo es indagar sobre la posibilidad de interpretar algunos conceptos foucaultianos como antecedentes del pensamiento de Rancière, en referencia al estudio sobre los modos de subjetivación en la educación. El análisis de la lógica de la verdad en Foucault y su diagnóstico de las sociedades de normalización encuentran cierta continuidad en la crítica rancieriana a la explicación y a la sociedad del menosprecio. Ambos hacen foco en las prácticas que intervienen en la constitución subjetiva. Rancière restablece en el eje central del análisis filosófico-educativo lo que, paradójicamente, bajo el nombre de Foucault iba perdiendo vigor: el sujeto.

Hongos arbusculares (Glomeromycota) en la rizosfera de Atriplex lampa en dos ambientes salinos de Córdoba: influencia de la profundidad en la colonización radical y presencia de morfoespecies Soteras, María Florencia; Cofré, María Noelia; Bartoloni, José; Cabello, Marta Noemi; Becerra, Alejandra Atriplex lampa es un arbusto halófito de la provincia fitogeográfica Chaqueña que constituye un recurso forrajero a lo largo de todo el año. Las plantas halófitas se benefician al asociarse con los hongos micorrícico arbusculares (HMA), ya que le proveen resistencia contra la salinidad y la sequía. En general, los estudios acerca de los HMA están restringidos a los primeros centímetros del suelo y existe poca información sobre su presencia a mayores profundidades. El objetivo de este trabajo fue estudiar la colonización, la concentración radical e identificar las morfoespecies de HMA en la rizosfera de A. lampa en dos ambientes salinos del norte de la provincia de Córdoba, durante dos estaciones del año, y en cinco profundidades del suelo. Aunque no se encontraron arbúsculos, A. lampa presentó colonización radical por HMA en todas las profundidades. El mayor valor de colonización micorrícica y de concentración radical se observó en las Salinas Grandes. Se identificaron 20 morfoespecies de HMA pertenecientes a los géneros: Acaulospora, Ambispora, Claroideoglomus, Diversispora, Funneliformis, Glomus, Septoglomus y Scutellospora. Este es el segundo registro en Argentina de la presencia de HMA en raíces de A. lampa. Es necesario realizar estudios que evalúen la respuesta de A. lampa frente a la inoculación con HMA para confirmar la funcionalidad de la simbiosis.; Arbuscular fungi (Glomeromycota) in the rhizosphere of Atriplex lampa at two saline environments of Córdoba (Argentina): depth infuence on root colonization and the presence of morphospecies. Atriplex lampa is a valuable fodder shrub available for browsing by livestock even during drought periods in the Chaco Phytogeographical Province. Halophytes may beneft from the association with arbuscular mycorrhizal fungi (AMF) through improved tolerance to drought and salt. Ecological studies of AMF are generally restricted to the main rooting zone. However, AMF vertical distribution and seasonal dynamics in natural saline soils of Argentina have been poorly studied. The aim of this work was to explore AMF root colonization, root concentration and to identify AMF morphoespecies in A. lampa rhizosphere in two saline environments (Salinas de Ambargasta and Salinas Grandes) of central Argentina, in fve soil depth levels, during the wet and dry seasons. Despite we did not fnd arbuscules, AMF were found colonizing A. lampa roots in all depth levels. Salinas Grandes showed the highest root colonization value, and showed the highest root concentration, during wet season. The 20 AMF morphospecies identifed in this work belonged to the genera: Acaulospora, Ambispora, Claroideoglomus, Diversispora, Funneliformis, Glomus, Septoglomus and Scutellospora. This is the second record in Argentina of AMF structures in A. lampa roots. Future studies that evaluate mycorrhizal dependency of the plant are necessary to confrm the function of the symbiosis.

Cell wall modifications and ethylene-induced tolerance to non-chilling peel pitting in citrus fruit Vicente, Ariel Roberto; Manganaris, George A.; Minas, Ioannis S.; Goulas, Vlasios; Lafuente, Maria T. Non-chilling peel pitting (NCPP), a storage disorder resulting in the formation of depressed areas in the peel of many citrus cultivars, is reduced by ethylene treatments. We hypothesized that this effect may be associated with biochemical changes of cell wall components. Therefore, we extracted cell wall material from albedo and flavedo tissues of ‘Navelate’ oranges stored in air, conditioned with ethylene (2 L L−1) for 4 days and subsequently transferred to air, or continuously stored in an ethylene-enriched atmosphere (2 L L−1). Uronic acids and neutral sugars were extracted into five fractions enriched in specific wall polymers namely water-, CDTA-, Na2CO3-, and 1 and 4 M KOH-soluble fractions. Pectin insolubilization was found in control fruit at long storage times. Ethylene treatments, alleviating NCPP, increased polyuronide solubility in the albedo and had a slight effect on the flavedo. Ethylene-treated fruit showed greater content of water-soluble neutral sugars and a larger proportion of hemicelluloses readily extractable with 1 M KOH, with a concomitant reduction in the 4 M KOH-soluble fraction. This suggests that the protective role of ethylene on NCPP is associated with an increased solubilization of the wall of albedo cells.

Liquid phase densification of Al-4.5 wt.% Cu powder reinforced with 5 wt.% Saffil short fibers during hot pressing Moreno, M. F.; Gonzalez Oliver, Carlos Julian R. The Alumix 13 (wt.%) (Al–4.5 Cu 0.5 Mg 0.2 Si) powder with and without 5 wt.% Saffil short fibers specimens were hot pressed in the range 580–620 °C. The densification during pressure increase was fitted using the Konopicky model and an agreement with the associated linear plot P vs. ln(1/(1 − D) was found for both materials, where P is applied pressure and D is the relative density of the porous material. The transient liquid phase formed from the elemental Al and Cu powder particles above the eutectic temperature of 548 °C at low hot pressing pressures, allows to increase the densification due to the reduction in the yield stress of the porous material. The active liquid flow enhanced the deformation between Al particles in the beginning of the pressure ramp. For higher pressures, a sudden break to a higher slope in Konopicky plot was found. This hardening behavior was detected from 610 °C for pure Alumix 13 and it was systematically developed at 580, 600, 610 and 620 °C for the composites, and it can be assigned to diffusion of Cu into the Al grains. During the constant pressure stage the densification was well fitted using the Power Law Creep model with exponents of n = 1 and n = 2, which are related to Newtonian viscous flow and superplastic deformation, respectively. Besides, final hot pressed composites samples retained an important quantity of solidified liquid phase located in between the Saffil fibers agglomerates.

Los modos de ser contingentes de lo político en el acontecimiento teatral Sequeira, María Jazmín Con la crisis del 2001 resurgieron cuestionamientos sobre el sentido político del teatro. Las preguntas y desacuerdos sobre el concepto que define lo político en el acontecimiento teatral reflejaron la incertidumbre frente a los rasgos inéditos de lo social y anunciaron la necesidad de crear renovadas claves de lectura según las demandas de los nuevos tiempos. Algunos interrogantes que continúan abiertos: ¿es pertinente asociar el teatro -siendo específicamente un acontecimiento poético- a un discurso político?, si es así: ¿qué tipo de discurso puede ser político y qué no?; ¿en qué sentido, de qué forma, puede ser político el acontecimiento poético de los cuerpos que excede las significaciones?; ¿existen grados distintos de politicidad?, o ¿todo es político?; ¿qué significa entonces lo político: lo concerniente al gobierno de la comunidad, lo concerniente al autogobierno en comunidad, lo concerniente a las ideologías y hechos sobre el estar con otros?; ¿es acaso la función del teatro en relación a lo social lo que significa su ser y reflexión políticos?, si es así: ¿qué función y qué utilidad se le atribuye? En este trabajo se propone tensionar estos interrogantes con algunos aportes de las teorías políticas de la corriente de pensamiento posfundacional estudiada particularmente por Oliver Marchart (2011).

Del lado de lo que sigue vivo Sequeira, María Jazmín Este artículo despliega un trayecto subjetivo sobre la memoria de Jorge Díaz, director teatral y docente del Departamento de Teatro de la Universidad de Córdoba fallecido en el año 2003. A través del recuerdo de su labor docente en la Facultad de Artes se reviven las marcas significativas y las huellas emancipantes de su legado aún vivo en el campo teatral actual.

Middle Eocene-Oligocene Broken Foreland Evolution In The Andean Valle Calchaqui, Nw Argentina: Insights From Stratigraphic, Structural And Provenance Studies del Papa, Cecilia Eugenia; Hongn, Fernando Daniel; Powell, Jaime Eduardo; Payrola, P.; Do Campo, Margarita Diana; Strecker, M.; Petrinovic, Ivan Alejandro; Schmitt, A.; Pereyra Hafner, Ricardo Eduardo Two end-member models have been proposed for the Paleogene Andean oreland: a simple W-Emigrating foreland model and a broken-foreland model. We present new stratigraphic, sedimentological and structural data from the Paleogene Quebrada de los Colorados (QLC) Formation, in the Eastern Cordillera, with which to test these two different models. Basin-wide unconformities, growthstrata and changes in provenance indicate deposition of the QLC Formation in a tectonically active basin. Both west- and east-vergent structures, rooted in the basement, controlled the depositionand distribution of the QLC Formation from the Middle Eocene to the Early Miocene. The provenance analysis indicates that the main source areas were basement blocks, like the Paleozoic Oire Eruptive Complex, uplifted during Paleogene shortening, and that delimits the eastern boundary of the present-day intraorogenic Puna plateau. A comparison of the QLC sedimentary basin-fill pattern with those of adjacent Paleogene basins in the Puna plateau and in the Santa Barbara System highlights the presence of discrete depozones. These reflect the early partmentalization of the foreland, rather than a stepwise advance of the deformation front of a thrust belt. The early Tertiary foreland of the southern central des is represented by a ca. 250-km-wide area comprising several deformation zones (Arizaro, Macon, Copalayo and Calchaquı) in which doubly vergent or asymmetric structures, rooted in the basement, were generated. Hence, lassical foreland model is difficult to apply in this Paleogene basin; and our data and interpretation agree with a broken-foreland model.

Impact of enriched analyses on regional numerical forecasts over Southeastern South America during SALLJEX Garcia Skabar, Yanina; Nicolini, Matilde During the warm season 2002-2003, the South American Low-Level Jet Experiment (SALLJEX) was carried out in southeastern South America. Taking advantage of the unique database collected in the region, a set of analyses is generated for the SALLJEX period assimilating all available data. The spatial and temporal resolution of this new set of analyses is higher than that of analyses available up to present for southeastern South America. The aim of this paper is to determine the impact of assimilating data into initial fields on mesoscale forecasts in the region, using the Brazilian Regional Atmospheric Modeling System (BRAMS) with particular emphasis on the South American Low-Level Jet (SALLJ) structure and on rainfall forecasts. For most variables, using analyses with data assimilated as initial fields has positive effects on short term forecast. Such effect is greater in wind variables, but not significant in forecasts longer than 24 hours. In particular, data assimilation does not improve forecasts of 24-hour accumulated rainfall, but it has slight positive effects on accumulated rainfall between 6 and 12 forecast hours. As the main focus is on the representation of the SALLJ, the effect of data assimilation in its forecast was explored. Results show that SALLJ is fairly predictable however assimilating additional observation data has small impact on the forecast of SALLJ timing and intensity. The strength of the SALLJ is underestimated independently of data assimilation. However, Root mean square error (RMSE) and BIAS values reveal the positive effect of data assimilation up to 18-hours forecasts with a greater impact near higher topography.; Durante a temporada quente de 2002-2003 foi realizado o South American Low-Level Jet Experiment (SALLJEX) no sudeste da América do Sul. Aproveitando-se da base de dados única coletados na região, um conjunto de análises foi gerado para o período SALLJEX, assimilando todos os dados disponíveis. A resolução espacial e temporal deste novo conjunto de análises é maior do que a das análises disponíveis até hoje para o sudeste da América do Sul. O objetivo deste trabalho é determinar o impacto de assimilação de dados em campos iniciais das previsões de mesoescala na região, utilizando o Brazilian Regional Atmospheric Modeling System (BRAMS), com ênfase particular na estrutura do Jato em Baixos Níveis na América do Sul (LLJSA) e nas previsões de precipitação. Para a maioria das variáveis, o efeito de utilizar as análises numéricas com dados assimilados nos campos iniciais é positivo nas previsões de curto prazo. Esse efeito é maior nas variáveis de vento, porém não é significativo nas previsões superiores a 24 horas. Em particular, a assimilação de dados não melhora as previsões de 24 horas da precipitação acumulada, mas tem pequenos efeitos positivos na precipitação acumulada entre 6 e 12 horas de previsão. Como o foco principal é a representação do LLJSA, o efeito de assimilação de dados na sua previsão foi explorado. Os resultados mostram que LLJSA é bastante previsível, entretanto quando dados observados adicionais são assimilados, o impacto é pequeno na previsão durante o tempo de integração e na previsão da intensidade do LLJSA. A intensidade do LLJSA é subestimada independente da assimilação de dados. No entanto, o erro quadrático médio (RMSE) e os valores do Viés revelam os efeitos positivos da assimilação de dados até 18 horas de previsão, com maior impacto perto de topografia.