Microfitobenton del Canal Mercante (Provincia de Buenos Aires) en dos condiciones hidrológicas Dos Santos, Analía Beatriz; Casco, Maria Adela; Claps, Maria Cristina In lotic environments, the erosion-sedimentation processes related to the hydrological conditions differ throughout the hydrological cycle, mainly due to rainfall. These processes can produce disturbances in the phytobenthic community. In canals, the current velocity and the water level are the main forcing variables that act on benthic communities, promoting changes in their structure, composition and biomass. Sediment samples were collected in the canal Mercante during two hydrological conditions: 1) at the beginning of spring, during a period of low rainfall (September 2009) and 2) in early autumn after a summer period with heavy rains (March 2010) to determine the content of organic matter, total phosphorus, chlorophyll a, and also the abundance of microphytobenthic individuals and cells. Simultaneously, some variables were measured in the water column. We identified two states of the community that could be associated with the phenomena of erosion / deposition related to the effect of water flow. In September the algal community in sediments showed a vertical architecture, mainly constituted by benthic algae among which several species had an aggregated distribution. In March, a decrease of the proportion and number of benthic algae was observed coinciding with the presence of planktonic species in sediments. Some benthic taxa exhibited similar abundances in the two periods and could be consider as tolerant to changes in flow velocity and as typical members of the canal Mercante. In conclusion, hydrological changes could have a significant role on the structure and dynamic of phytobenthon.

Variation Operators for Semigroups and Riesz Transforms on BMO in the Schrödinger Setting Betancor, Jorge J.; Fariña, Juan C.; Harboure, Eleonor Ofelia; Rodriguez Mesa, Lourdes In this paper we prove that the variation operators of the heat semigroup and the truncations of Riesz transforms associated to the Schrödinger operator are bounded on a suitable BMO type space.

Hegemonía empresaria en el esplendor y ocaso de YPF: el caso de la petrolera argentina Palermo Haber, Hernán Manuel Partiendo de la perspectiva que entiende la experiencia de clase como un proceso históricamente situado que conecta condiciones subjetivas y estructurales, abordaremos las continuidades y rupturas de las experiencias obreras en intima vinculación con los procesos de constitución de hegemonía en el trabajo. Por lo tanto, atendiendo lo subjetivo en dialéctica con lo estructural, esta investigación propone un recorrido histórico sobre la creación y consolidación de la empresa YPF (Yacimientos Petrolíferos Fiscales) durante su gestión estatal, luego aborda las distintas dimensiones del proceso de privatización (uno de los más emblemáticos de la historia argentina reciente) hasta su compra por la empresa española Repsol, haciendo hincapié en aquellos aspectos que configuran la denominada hegemonía empresaria.; Starting from the perspective that understands the class (group) experience as a process historically located which connects subjective and structural conditions, we will deal with the continuities and interruptions of the workers experiences in deep connection with worrking conditions transformations. Our research stems from the study of a collective of work as state oil workers at YPF in their development as social subjects and in the transformation of this collective to the light of the political economic and social processes in the Argentina of the post privatization era. Thus we deal with the state period of the company, the breaking imposed by privatization and the period of private ownership.

Innate immune sensing of cancer: clues from an identified role for type I IFNs Gajewski, Thomas F.; Fuertes, Mercedes Beatriz; Woo, Seng Ryong A subset of patients with a variety of cancers shows evidence of a natural adaptive immune response against their tumor, as evidenced by spontaneous T-cell infiltration, circulating anti-tumor T cells, or antibody responses. Evidence has indicated that such natural immune responses have positive prognostic import in early stage disease and may be predictive of clinical response to immunotherapeutics in advanced disease. However, these observations raise a new critical fundamental question?what innate immune signals might be generated in the context of non-pathogen-induced cancers that drive productive antigen presentation toward induction of an adaptive immune response? Gene expression profiling in melanoma revealed that tumors having high expression of T-cell markers also show evidence of a type I IFN transcriptional signature. Mechanistic experiments in mice have revealed that a spontaneous CD8+ T-cell response against transplantable tumors depends on host type I IFN signaling, through a mechanism dependent upon CD8α+ dendritic cells (DCs). The requirement for type I IFN production by host DCs has suggested a subset of innate immune sensing receptors and signaling pathways that might be involved with initiating this process. Elucidating further these innate immune mechanisms should provide new insights into cancer immunotherapy.

Neural encoding schemes of tactile information in afferent activity of the vibrissal system Farfan, Fernando Daniel; Albarracin, Ana Lia; Felice, Carmelo Jose When rats acquire sensory information by actively moving their vibrissae, a neural code is manifested at different levels of the sensory system. Behavioral studies in tactile discrimination agree that rats can distinguish different roughness surfaces by whisking their vibrissae. The present study explores the existence of neural encoding in the afferent activity of one vibrissal nerve. Two neural encoding schemes based on “events” were proposed (cumulative event count and median inter-event time). The events were detected by using an event detection algorithm based on multiscale decomposition of the signal (Continuous Wavelet Transform). The encoding schemes were quantitatively evaluated through the maximum amount of information which was obtained by the Shannon’s mutual information formula. Moreover, the effect of difference distances between rat snout and swept surfaces on the information values was also studied. We found that roughness information was encoded by events of 0.8 ms duration in the cumulative event count and event of 1.0 to 1.6 ms duration in the median inter-event count. It was also observed that an extreme decrease of the distance between rat snout and swept surfaces significantly reduces the information values and the capacity to discriminate among the sweep situations.

The star cluster age-metallicity relationship in the Small Magellanic Cloud Piatti, Andres Eduardo We present CCD Washington photometry of 11 Small Magellanic Cloud (SMC) clusters for which age and metallicity estimates are provided. The 11 clusters are witnesses of the ∼ 2 Gyr bursting formation episode, according to their positions in the age-metallicity relationship (AMR). We added these clusters to the largest known SMC cluster sample with ages and metallicities put into an homogeneous scale, and found that two enhanced formation episodes at t ∼ 2 and 5-6 Gyr throughout the entire body of the galaxy, the absent of a metallicity gradient and a relative spread in metallicity for clusters older than ∼ 7 Gyr comprehensively describe the SMC AMR. In addition, based on the statistics of catalogued and studied clusters, we found that a total of seven relatively old/old clusters have not yet studied, and even a smaller number is obtained if the cluster spatial distribution is considered. A detailed version of this work can be seen in Piatti (2011, MNRAS, 418, L73).; Presentamos resultados sobre edades y metalicidades obtenidos a partir de fotometría CCD en el sistema de Washington para 11 cúmulos en la Nube Menor de Magallanes (NMM). Los 11 cúmulos resultaron ser testigos de un episodio de formación violento hace unos 2 mil millones de a˜nos, de acuerdo a su posición en la relación edad metalicidad (REM). Incluimos estos cúmulos a la muestra m´as numerosa de cúmulos en la NMM con edades y metalicidades estimadas en una escala homogénea, y encontramos que dos episodios de formación violentos hace unos 2 y 5-6 mil millones de a˜nos en todo el cuerpo de la galaxia, la ausencia de un gradiente de metalicidad y una relativa dispersión de las metalicidades para edades mayores a 7 mil millones de a˜nos describen globalmente la REM de la NMM. Además, en base a la estad´ıstica de los cúmulos catalogados y estudiados, encontramos que un total de 7 cúmulos viejos no han sido a´un estudiados, y un n´umero menor obtenemos si consideramos sus distribuciones espaciales.Una versión detallada de este trabajo puede verse en Piatti (2011, MNRAS, 418, L73).

Astrophysical properties of star fields in the Large Magellanic Cloud Piatti, Andres Eduardo We present CCD Washington CT1 photometry for the unprecedented database of some 5.5 million of stars distributed throughout the entire Large Magellanic Cloud (LMC) main body. The quality and performance of the data were rigurously examined from extensive completeness artificial star tests over the whole mosaic image data set, so that field colour-magnitude diagrams (CMDs) were accurately produced. From the star field CMD Hess diagrams, we identified the peaks at the main -sequence turnoff and red clump locations to date the most dominant sub-population (or ”representative” population) in the stellar population mix, while their metallicities were estimated from the CMD location of the most populous red giant branch track. The dispersion associated with the mean ages and metallicities result in general a satisfactory estimate of the age/metallicity spread, although some few individual representative subfields have slightly larger age/metallicity spread. As far as we are aware, these larger age spread do not affect the subsequent analysis. A detailed version of this work can be seen in Piatti et al. (2012, AJ, 144, 100).

The star field age-metallicity relationship in the Large Magellanic Cloud Piatti, Andres Eduardo Presentamos resultados obtenidos a partir de datos CCD en el sistema fotométrico de Washington de ∼ 5.5 millones de estrellas distribuidas en toda la Nube Mayor de Magallanes (NMM). La calidad y performance de los datos fueron rigurosamente examinados a partir de numerosas pruebas de completitud con estrellas artificiales en todo el conjunto de imágenes mosaico, de modo que diagramas colormagnitud (DCM) fueron precisamente confeccionados. A partir de los DCM de Hess de las estrellas del campo, identificamos los picos del turnoff de la secuencia principal y del clump de las gigantes rojas para datar la sub-población más dominante (o población representativa) en la composición de poblaciones estelares, mientras que sus metalicidades fueron estimadas a partir de la ubicación de la rama de las gigantes rojas más poblada. La dispersión asociada con las edades y metalicidades medias resulta en general una estimación satisfactoria de la dispersión edad/metalicidad, aunque algunos pocos subcampos representativos individuales tienen una ligeramenta mayor dispersión edad/metalicidad. Hasta donde estamos seguros, esta mayor dispersión en edad no afecta posteriores análisis. Una versión detallada de este trabajo puede verse en Piatti et al. (2012, AJ, 144, 100).; We present CCD Washington CT1 photometry for the unprecedented database of some 5.5 million of stars distributed throughout the entire Large Magellanic Cloud (LMC) main body. The quality and performance of the data were rigurously examined from extensive completeness artificial star tests over the whole mosaic image data set, so that field colour-magnitude diagrams (CMDs) were accurately produced. From the star field CMD Hess diagrams, we identified the peaks at the main-sequence turnoff and red clump locations to date the most dominant sub-population (or ”representative” population) in the stellar population mix, while their metallicities were estimated from the CMD location of the most populous red giant branch track. The dispersion associated with the mean ages and metallicities result in general a satisfactory estimate of the age/metallicity spread, although some few individual representative subfields have slightly larger age/metallicity spread. As far as we are aware, these larger age spread do not affect the subsequent analysis. A detailed version of this work can be seen in Piatti et al. (2012, AJ, 144, 100).

Scalar field perturbations in asymptotically Lifshitz black holes Giacomini, Alex; Giribet, Gaston Enrique; Leston, Mauricio; Oliva, Julio; Ray, Sourya We consider scalar field perturbations about asymptotically Lifshitz black holes with dynamical exponent z in D dimensions. We show that, for suitable boundary conditions, these Lifshitz black holes are stable under scalar field perturbations. For z=2, we explicitly compute the quasinormal mode frequencies, which result to be purely imaginary, and then obtain the damping-off of the scalar field perturbation in these backgrounds. The general analysis includes, in particular, the z=3 black hole solution of three-dimensional massive gravity.

First Archaeal rDNA sequences from coastal waters of Argentina: unexpected PCR characterization by using eukaryotic primers Covacevich, Fernanda; Silva, R. I.; Cumino, Andrea Carina; Caló, Gonzalo Federico; Negri, R. M.; Salerno, Graciela Lidia Muchos miembros de Archaea, un grupo de microroganismos descritos hace aproximadamente 30 años, colonizan ambientes extremos. Sin embargo, las investigaciones más recientes han demostrado que las arqueas también son abundantes componentes del plankton marino, siendo algunos grupos de Archaea componentes fundamentales de los ecosistemas marinos debido a su rol clave en los ciclos biogeoquímicos. Aunque la ubiquidad de las arqueas ha sido bien documentada, hasta el momento no hay registros de la presencia de representantes de este grupo en el mar Argentino. En un estudio de biodiversidad orientado a determinar secuencias de picoplancton utilizando cebadores universales para eucariotas, se encontraron secuencias de ADNr de Archaea en muestras recolectadas durante la primavera en una estación fija de monitorización (EPEA) en el mar Argentino. A partir de ADN ambiental y mediante el uso de la metodología de PCR, se obtuvieron dos fragmentos de aproximadamente 1700 y 1460 pb, que fueron separados y visualizados después de electroforesis en geles de agarosa y, luego, purificados, clonados y secuenciados. El análisis de BLAST mostró que las secuencias de tamaño superior correspondían a organismos eucariotas y las secuencias de menor tamaño pertenecían a Archaea. El análisis filogenético mostró que las secuencias de Archaea se agrupan con Euryarchaeota marina grupo II, caracterizado como un linaje metanógeno. Éste es el primer reporte de la presencia de secuencias de Euryarchaeota grupo II en aguas del mar Argentino. El hecho de que las secuencias de Archaea hayan sido amplificadas con cebadores no específicos para este grupo podría sugerir una inesperada abundancia de estos organismos durante los inicios de primavera en el mar Argentino.; Many members of Archaea, a group of prokaryotes recognized three decades ago, colonize extreme environments; however, new research has shown that Archaeans are also abundant components of plankton in the open sea, where they play a key role in the biogeochemical cycles. Although the widespread distribution of Archaea in the marine environment is well documented there are no reports on the detection of Archaea in the Southwest Atlantic Ocean. During the search for picophytoplankton sequences using eukaryotic universal primers, we retrieved archaeal rDNA sequences from surface samples collected during the spring at a fixed monitoring station (EPEA) in the Argentine Sea. From environmental DNA and using PCR methodology, two DNA fragments of about 1700 and 1450 bp were visualized after electrophoresis in agarose gels, and separately purified, cloned, and sequenced. BLAST analysis showed that sequences of the highest size corresponded to eukaryotic organisms and, unexpectedly, those of about 1460 bp corresponded to archaeal organisms. Phylogenetic analysis showed that archaeal sequences belong to Euryarchaeota of marine group II, characterized as a methanogenic lineage. This is the first report on the presence of group II Euryarchaeota sequences in environmental water samples of the Argentine Sea. The fact that Archaea sequences were amplified with primers non-specific for this group may suggest an unexpected abundance of these organisms in the early spring in the Argentine Sea.

Spectrofluorimetric determination of sildenafil: a new analytical alternative for its analysis Wang, Chien Chun; Fernandez, Liliana Patricia In aqueous solutions, sildenafil presents a very low fluorescence emission and a limited linear range. In presence of a cationic surfactant hexadecyltrim ethylammonium bromide (HTAB, method A) and anionic surfactant sodium dodecyl sulfate (SDS, method B) a great fluorescence enhancement was observed and the linearity range was enlarged. These surfactants-drug interactions lead to the development of two sensitive methods for sildenafil spectrofluorimetric determination. Nature of interactions between sildenafil and surfactants were studied and different parameters which influence these associations were discussed. Sildenafil was quantitatively determined at an emission wavelength of 435 nm and 415 nm by method A and B respectively with detection limit of 0.0012 µg mL-1 and 0.0016 µg mL-1. The methods have been successfully applied to the analysis of bulk drug, tablets and herbal medicines.

Silvopastoral use of Nothofagus antarctica in Southern Patagonian forests, influence over net nitrogen soil mineralization Bahamonde, Hector Alejandro; Peri, Pablo Luis; Alvarez, Roberto; Barneix, Atilio Jose; Moretto, Alicia Susana; Martínez Pastur, Guillermo José In most temperate forest, nitrogen (N) is considered a limiting factor. This becomes important in extreme environments, as Nothofagus antarctica forests, where the antecedents are scarce. Thinning practices in N. antarctica forests for silvopastoral uses may modify the soil N dynamics. Therefore, the objective of this work was to evaluate the temporal variation of soil N in these ecosystems. The mineral extractable soil N, net nitrification and net N mineralization were evaluated under different crown cover and two site quality stands. The mineral N extractable (NH4 ??N ? NO3 -?N) was measured periodically. Net nitrification and net N mineralization were estimated through the technique of incubation of intact samples with tubes. The total mineral extractable N concentration varied between crown cover and dates, with no differences among site classes. The lowest and highest values were found in the minimal and intermediate crown cover, respectively. In the higher site quality stand, the annual net N mineralization was lower in the minimal crown cover reaching 11 kg N ha-1 year-1, and higher in the maximal crown cover (54 kg N ha-1 year-1). In the lower site quality stand there was no differences among crown cover. The same pattern was found for net nitrification. Thinning practices for silvopastoral use of these forests, keeping intermediate crown cover values, did not affect both N mineralization and nitrification. However, the results suggest that total trees removal from the ecosystem may decrease N mineralization and nitrification.

Documentary evidence for changing climatic and anthropogenic influences on the Bermejo Wetland in Mendoza, Argentina, during the 16th 20th century Prieto, Maria del Rosario; Rojas, Juan Facundo This paper examines the processes underlying changes to the once-extensive Bermejo Wetland, east of the city of Mendoza, Argentina (32550 S, 68510 W). Historical documents and maps from the 16th to 20th century are used to reconstruct environmental shifts. Historical documents indicate periods of increased snowfall in the adjacent Andes mountains, as well as high flow volumes in the Mendoza River. Data from georeferenced maps, the first from 1802 and the last from 1903, reflect the changes in the surface area of the wetland. The combined data sets show pulses of growth and retraction, in which major expansions coincided with more intense snowstorms and increased flow in the Mendoza River, which in turn influenced socio-economic activities. The wetland became progressively drier during the 19th century, before drying up completely around 1930, due in part to the construction of drainages and channels.

Research priorities for seabirds: improving conservation and management in the 21st century Lewison, R.; Oro, D.; Godley, B. J.; Underhill, L.; Bearhop, S.; Wilson, R. P.; Ainley, D.; Arcos, J. M.; Boersma, P. Dee; Garcia Borboroglu, Jorge Pablo; Boulinier, T.; Frederiksen, M.; Genovart, M.; González Solís, J.; Green, J. A.; Grémillet, D.; Hamer, K. C.; Hilton, G. M.; Hyrenbach, K. D.; Martínez Abraín, A.; Montevecchi, W. A.; Phillips, R. A.; Ryan, P. G.; Sagar, P.; Sydeman, W. J.; Wanless, S.; Watanuki, Y.; Weimerskirch, H.; Yorio, Pablo Martin Seabirds, a diverse group of bird species associated with the ocean during a significant part of their lives, are facing a growing number of threats in both their terrestrial and marine habitats, and many populations have experienced dramatic changes over the past decades. Seabirds are among the best-studied of marine vertebrates; years of research have played a central role in improving our understanding of seabird populations and have informed a broader understanding of marine ecological processes. In an effort to encourage future research and guide science directed at improving seabird population and habitat management and conservation, we identify 20 key areas where continued, robust and comprehensive inter-disciplinary science is most needed. Twenty-seven seabird researchers from 9 nations identified the 20 highest priority research questions, which were organized into six general categories: (i) population dynamics, (ii) spatial ecology, (iii) tropho-dynamics, (iv) fisheries interactions, (v) response to global change, and (vi) management of anthropogenic impacts (focusing on invasive species, contaminants and protected areas). While this is not an exhaustive list of all research needed to address the myriad conservation challenges seabirds face, the results of this effort represent an important synthesis of current expert opinion across sub-disciplines within seabird ecology. As this synthesis highlights, research, in conjunction with direct management, education, and community engagement, can play an important role in facilitating the conservation and management of seabird populations and of the ocean ecosystems on which they and we depend.

Association of AXIN2 with Non-syndromic Oral Clefts in Multiple Populations. Letra, A.; Bjork, B.; Cooper, M. E.; Szabo Rogers, H.; Deleyiannis, F. W.; Field, L. L.; Czeizel, A. E.; Ma, L.; Garlet, G. P.; Poletta, Fernando Adrián; Mereb, J. C.; López Camelo, Jorge Santiago; Castilla, Eduardo Enrique; Orioli, I. M.; Wendell, S.; Blanton, S. H.; Liu, K.; Hecht, J. T.; Marazita, M. L.; Vieira, A. R.; Silva, R. M. We have previously shown the association of AXIN2 with oral clefts in a US population. Here, we expanded our study to explore the association of 11 AXIN2 markers in 682 cleft families from multiple populations. Alleles for each AXIN2 marker were tested for transmission distortion with clefts by means of the Family-based Association Test. We observed an association with SNP rs7224837 and all clefts in the combined populations (p = 0.001), and with SNP rs3923086 and cleft lip and palate in Asian populations (p = 0.004). We confirmed our association findings in an additional 528 cleft families from the United States (p < 0.009). We tested for gene-gene interaction between AXIN2 and additional cleft susceptibility loci. We assessed and detected Axin2 mRNA and protein expression during murine palatogenesis. In addition, we also observed co-localization of Axin2 with Irf6 proteins, particularly in the epithelium. Our results continue to support a role for AXIN2 in the etiology of human clefting. Additional studies should be performed to improve our understanding of the biological mechanisms linking AXIN2 to oral clefts.

Sindicalismo empresarial: problemas, conceptualización y economía política del sindicato Ghigliani, Pablo Esteban; Grigera, Juan Francisco; Schneider, Alejandro Miguel Revista Latino-americana de Estudos do Trabalho reSumen El artículo revisa críticamente los abordajes que ha tenido el “sindicalismo empresarial” desde las ciencias sociales en Argentina, argumentando que las aproximaciones existentes son insuficientes para dar cuenta del problema desde una dimensión socio-histórica y que los análisis se fundan en recortes que pierden de vista la imbricación del fenómeno en la economía política del sindicato. De este modo identificamos las dos corrientes más relevantes que han abordado el sindicalismo empresarial: quienes lo explicaron como ‘supervivencia organizativa’, reduciéndolo a un producto derivado de las negociaciones y concesiones que permitieron al gobierno evitar el enfrentamiento con las centrales obreras durante las reformas y quienes lo han asimilado a una modalidad más del business unionism norteamericano, perdiendo de vista la especificidad del fenómeno. El artículo concluye planteando un nuevo abordaje del tema y delineando los elementos fundamentales de análisis.; The article critically reviews studies on what the authors call “entrepreneurship unionism” in Argentina, identifying two major sets of arguments in the literature: those that explain it as a tactic of “organizational survival”, reducing it to a byproduct of negotiations and concessions by which the Menem administration could avert confrontation with unions during the reforms; and those that define it as a form of the United States’ “business unionism”, losing sight of the specificity of the phenomenon. The authors argue, first, that these approaches are insufficient to explain the socio-historical dimensions of the phenomenon; and second, that they lose sight of the array of social relations that constitute the economic mechanisms of unions’ material reproduction, that is, its political economy. In conclushion, the article outlines new approaches to the issue and identifies key elements of analysis.

Modos de habitar y estilos de vida. El espacio doméstico en las revistas especializadas Sanchez, Sandra Ines Las publicaciones especializadas han tenido desde siempre un rol difusor de las nuevas teorías sobre el ejercicio proyectual, la arquitectura y el diseño de objetos. Con el énfasis puesto de manera diferenciada en los campos disciplinar, profesional y académico, en estas publicaciones se evidenciaba siempre la construcción de un conocimiento proyectual que trascendía los programas arquitecturales, y la intencionalidad de acoplarse a las transformaciones culturales planteando respuestas que ponían en crisis la misma índole de las transformaciones. El trabajo consiste en el análisis de las cuestiones culturales que refieren a los usuarios y sus preferencias, modos de habitar, estilos de vida y estilizaciones que se encuentran profundamente más allá de la enseñanza del proyecto pero que atraviesan transversalmente el ejercicio proyectual aplicado al espacio doméstico, a partir de un estudio de algunos casos emergentes seleccionados de diferentes publicaciones especializadas de Buenos Aires desde la década del treinta hasta la actualidad.; Specialized publications have always focused on spreading the new theories about project planning, architecture and objects design. With a special emphasis laid on the professional and academic scopes, these publications constantly envisaged the development of project planning knowledge far beyond architectural programs with an intent to adjust to cultural transformations by producing replies that challenged the very nature of such transformations. The work involves the analysis of those cultural issues linked to users and their preferences, dwelling forms, life styles and stylizations that outreach project teaching but are however related to project practice applied to the household environment, as emerges from the analysis of certain cases extracted from various Buenos Aires‟ specialized publications since the „60s up to the present time.

Remarks on annihilators preserving congruence relations Celani, Sergio Arturo In this note we shall give some results on annihilators preserving congruence relations, or AP-congruences, in bounded distributive lattices. We shall give some new characterizations, and a topological interpretation of the notion of annihilator preserving congruences introduced in [JANOWITZ, M. F.: Annihilator preserving congruence relations of lattices, Algebra Universalis 5 (1975), 391–394]. As an application of these results, we shall prove that the quotient of a quasicomplemented lattice by means of a AP-congruence is a quasicomplemented lattice. Similarly, we will prove that the quotient of a normal latttice by means of a AP-congruence is also a normal lattice.

La basura y la investigación sobre el pasado Perez, Cecilia Beatriz; Casanueva, María Laura Desde el desarrollo del Garbage Project de William Rathje, en la Universidad de Arizona, los arqueólogos se han inclinado frente a los residuos producidos por el hombre para indagar acerca de su génesis, ya que los consideran un espejo de la sociedad que los produjo. Por eso, los consideran una herramienta eficiente para analizar la conducta humana, más allá de lo que puedan los hombres decir sobre sí mismos.

Fracture toughness of HSLA coiled tubing used in oil wells operations Wainstein, Jessica Elvira; Perez Ipiña, Juan Elias Coiled Tubings are thin walled steel tubes of 25-89 mm diameter and thousands meters long, used in the oil industry for production and maintenance services. They suffer plastic deformation during unwinding of the reel, passing through a goosneck arch guide and an injector unit. Strain levels are of 2-3%, making the tubing fail by low cycle fatigue in around 100 wrap-unwrap cycles. As coiled tubing material generally behaves in a ductile manner at surface and down well temperatures, the R curve has to be known to make instability analyses. J-R curves were determined to characterize the fracture toughness of nonused coiled tubing, using nonstandard specimens due to difficulties with their small thickness and diameters. Different crack lengths and crack locations were tested to analyze the 2C 0W ratio and the influence of the longitudinal weld. The R curves obtained show crack arc length dependence and are influenced by the position of the longitudinal weld.