Enhancing energy harvesting by coupling monostable oscillators Peña Rosselló, Julián Ignacio; Wio, Horacio Sergio; Deza, Roberto Raul; Hänggi, Peter The performance of a ring of linearly coupled, monostable nonlinear oscillators is optimized towards its goal of acting as energy harvester – through piezoelectric transduction – of mesoscopic fluctuations, which are modeled as Ornstein-Uhlenbeck noises. For a single oscillator, the maximum output voltage and overall efficiency are attained for a soft piecewise-linear potential (providing a weak attractive constant force) but they are still fairly large for a harmonic potential. When several harmonic springs are linearly and bidirectionally coupled to form a ring, it is found that counter-phase coupling can largely improve the performance while in-phase coupling worsens it. Moreover, it turns out that few (two or three) coupled units perform better than more.

Representantes del Ministerio de Ciencia de la Nación se reunieron con referentes provinciales, vinculadores federales y equipos técnicos de Catamarca, Santiago del Estero y La Rioja para repasar los criterios de evaluación y financiamiento de proyectos.

Loschmidt echo in many-spin systems: A quest for intrinsic decoherence and emergent irreversibility Zangara, Pablo René; Pastawski, Horacio Miguel If a magnetic polarization excess is locally injected in a crystal of interacting spins in thermal equilibrium, this 'excitation' would spread as consequence of spin-spin interactions. Such an apparently irreversible process is known as spin diffusion and it can lead the system back to 'equilibrium'. Even so, a unitary quantum dynamics would ensure a precise memory of the non-equilibrium initial condition. Then, if at a certain time, say , an experimental protocol reverses the many-body dynamics by changing the sign of the effective Hamiltonian, it would drive the system back to the initial non-equilibrium state at time t. As a matter of fact, the reversal is always perturbed by small experimental imperfections and/or uncontrolled internal or environmental degrees of freedom. This limits the amount of signal M(t) recovered locally at time t. The degradation of M(t) accounts for these perturbations, which can also be seen as the sources of decoherence. This general idea defines the Loschmidt echo (LE), which embodies the various time-reversal procedures implemented in nuclear magnetic resonance. Here, we present an invitation to the study of the LE following the pathway induced by the experiments. With such a purpose, we provide a historical and conceptual overview that briefly revisits selected phenomena that underlie the LE dynamics including chaos, decoherence, localization and equilibration. This guiding thread ultimately leads us to the discussion of decoherence and irreversibility as an emergent phenomenon. In addition, we introduce the LE formalism by means of spin-spin correlation functions in a manner suitable for presentation in a broad scope physics journal. Last, but not least, we present new results that could trigger new experiments and theoretical ideas. In particular, we propose to transform an initially localized excitation into a more complex initial state, enabling a dynamically prepared LE. This induces a global definition of the LE in terms of the raw overlap between many-body wave functions. Our results show that as the complexity of the prepared state increases, it becomes more fragile towards small perturbations.

Representantes del COFECYT, la Dirección de Cooperación e Integración Institucional y la Agencia Nacional de Promoción científica y Tecnológica viajaron a la provincia patagónica para reunirse con los equipos de evaluación locales y capacitar a emprendedores sobre la formulación de proyectos.

Tres nuevos equipos destinados a la investigación científica y tecnológica, con un costo superior a 26 millones de pesos, serán adquiridos por la Universidad Nacional de Río Cuarto (UNRC) con un subsidio de la Nación.

Human breast adipose tissue: characterization of factors that change during tumor progression in human breast cancer Fletcher, Sabrina Johanna; Sacca, Paula Alejandra; Pistone Creydt, Mercedes; Coló, Federico Andrés; Serra, María Florencia; Santiano, Flavia Eliana; Sasso, Corina Verónica; López Fontana, Constanza Matilde; Caron, Ruben Walter; Calvo, Juan Carlos; Pistone Creydt, Virginia Adipose microenvironment is involved in signaling pathways that influence breast cancer. We aim to characterize factors that are modified: 1) in tumor and non tumor human breast epithelial cell lines when incubated with conditioned media (CMs) from human breast cancer adipose tissue explants (hATT) or normal breast adipose tissue explants (hATN); 2) in hATN-CMs vs hATT-CMs; 3) in the tumor associated adipocytes vs. non tumor associated adipocytes. We used hATN or hATT- CMs on tumor and non-tumor breast cancer cell lines. We evaluated changes in versican, CD44, ADAMTS1 and Adipo R1 expression on cell lines or in the different CMs. In addition we evaluated changes in the morphology and expression of these factors in slices of the different adipose tissues. The statistical significance between different experimental conditions was evaluated by one-way ANOVA. Tukey's post-hoc tests were performed within each individual treatment. hATT-CMs increase versican, CD44, ADAMTS1 and Adipo R1 expression in breast cancer epithelial cells. Furthermore, hATT-CMs present higher levels of versican expression compared to hATN-CMs. In addition, we observed a loss of effect in cellular migration when we pre-incubated hATT-CMs with chondroitinase ABC, which cleaves GAGs chains bound to the versican core protein, thus losing the ability to bind to CD44. Adipocytes associated with the invasive front are reduced in size compared to adipocytes that are farther away. Also, hATT adipocytes express significantly higher amounts of versican, CD44 and Adipo R1, and significantly lower amounts of adiponectin and perilipin, unlike hATN adipocytes. We conclude that hATT secrete a different set of proteins compared to hATN. Furthermore, versican, a proteoglycan that is overexpressed in hATT-CMs compared to hATN-CMs, might be involved in the tumorogenic behavior observed in both cell lines employed. In addition, we may conclude that adipocytes from the tumor microenvironment show a less differentiated state than adipocytes from normal microenvironment. This would indicate a loss of normal functions in mature adipocytes (such as energy storage), in support of others that might favor tumor growth.

El Fondo Argentino Sectorial (FONARSEC) informa que se ha prorrogado la fecha de cierre para la presentación de proyectos para EMPRETECNO 2016.

Hipertiroidismo en un paciente canino con carcinoma folicular tiroideo; Canine hyperthyroidism in a patient with follicular thyroid carcinoma Maurenzig, Nelson Damian; Koscinczuk, Patricia; Polo, M. V.; Cainzos, Romina Paola La glándula tiroides, no es palpable en perros bajo condiciones normales, pero, ante la presencia de tumores, se perciben sin dificultad. Los tumores tiroideos representan el 1-4% de todas las neoplasias caninas. Lamayoria de las veces la presentación clínica es de eutiroideos o hipotiroideos. Solo cerca del 10% de los casos exhiben hipertiroidismo, generalmente asociado a cáncer tiroideo. El objetivo del trabajo es describir un caso de neoplasia de tiroides en un canino, macho de 10 años, de raza indefinida, que llegó a la consulta por presentar una deformación en la región ventro cervical y manifestar signos de poliuria, polidipsia, polifagia, pérdida de peso y disfagia, entre otros. Se realizó la palpación de la región cervical y se obtuvo muestra de la masa por punción aspiración con aguja fina (PAAF) que evidencio un carcinoma. Se extrajo muestra de sangre para el análisis de hemograma, bioquímica sérica y medición de hormona T4 libre, la cual se encontró aumentada, confirmando el diagnostico de hipertiroidismo. Además se efectuó una ecografía de la región del cuello y se obtuvo una imagen compatible con neoplasia tiroidea en el lóbulo izquierdo. El histopatológico realizado posterior a la tiroidectomía izquierda estableció que el carcinoma era del tipo folicular. Los incrementos anormales de la tiroxinemia confirman el diagnostico de hipertiroidismo, y debería sospecharse de un carcinoma funcional como causa. Estas neoplasias suelen presentarse en la edad media o avanzada. En pocos perros hipertiroideos, la masa cervical es la primera anormalidad advertida y el motivo para buscar atención médica. Ante tal circunstancia se recomienda la evaluación, en especial si el propietario refiere la presencia de signos adicionales.; The thyroid gland, when normal, is not palpable in dogs, but in the presence of tumors, generally malignant, it is easy to identify. Thyroid tumors represent 1-4% of all canine cancers, mainly producing euthyroid or hypothyroid situations. About 10% of the cases show signs of hyperthyroidism, almost always associated with thyroid cancer. The aim is to describe a case of thyroid neoplasm and hyperthyroidism in a 10-year-old male canine. The main issue was the presence of a mass in the ventral cervical region and the presence of clinical signs of hyperthyroidism such as polyuria, polydipsia, polyphagia, weight loss and dysphagia, among others. Palpation of the cervical region was performed, and a sample of the mass was obtained by fine needle aspiration (FNA) for cytologic exam. Carcinomatous cells were identified in the cytology. A sample of blood was drawn for blood cell count, serum biochemistry and measurement of free T4 hormone, which was increased, confirming the diagnosis of hyperthyroidism. An ultrasound of the neck region was also performed. A mass on the left thyroid lobe, compatible with thyroid neoplasia was found. Histopathology confirmed the diagnosis of follicular thyroid carcinoma. Unusual, increased levels of free T4 confirmed the diagnosis of hyperthyroidism, which should be suspected to be related to a functional carcinoma.

Marxismo y cuestión nacional Kohan, Néstor Boris El artículo explora la relación entre el marxismo y la cuestión nacional desde una óptica latinoamérica. Señala que puede apreciarse un viraje teórico dentro de la obra de Karl Marx, desde las investigaciones que realizó a partir de la década de los cincuenta del siglo xix. Dicho cambio en la mirada que Marx tuvo de las naciones periféricas fue abandonado por aquellos que trataron de desarrollar su legado teórico. Empero, el artículo avanza en la comprensión de la originalidad de algunos marxistas latinoamericanos como Ernesto Che Guevara o José Carlos Mariateguí para recuperar el sentido anti-imperialista de las luchas latinoamericanas en las cuales una figura como la de Simón Bolívar se vuelve fundamental para entender el devenir de las luchas de liberación en esta región.; The article explores the relationship between Marxism and the national question from a Latin American perspective. Notes that can be seen a theoretical shift in the work of Karl Marx, which from investigations carried out from the fifties of the nineteenth century. This change in the look that Marx had peripheral nations was abandoned by those who tried to develop their theoretical legacy. However, the article advances in the understanding of the originality of some Latin American Marxists like Ernesto Che Guevara or Jose Carlos Mariategui to recover the anti-imperialist struggles of the Latin American sense in which a figure like Simon Bolivar becomes essential to understand the future of the liberation struggles in this region.

Immobilization of a microbial consortium on Ca-alginate enhances degradation of cationic surfactants in flasks and bioreactor Bergero, Maria Fernanda; Liffourrena, Andres Sebastian; Opizzo Balza, Bianca; Fochesatto, A.S.; Lucchesi, Gloria Ines Free cells and Ca-alginate encapsulated cells of Aeromonas hydrophila MFB03 removed in shake flasks up to 65% of tetradecyltrimethylammonium bromide (TTAB) 30 mg l−1. While planktonic cells were unable to utilize 50 mg l−1 benzalkonium chloride (BAC) after 48 h of incubation, the immobilized cells of A. hydrophila MFB03 removed up to 90% of BAC (25–210 mg l−1) in the same period. A microbial immobilized consortium formed by A. hydrophila MFB03 and Pseudomonas putida A (ATCC 12633) was able to degrade, after 24–30 h, 65% of TTAB and 100% of BAC, both added at 50 mg l−1. BAC was completely removed by the consortium encapsulated in a stirred tank bioreactor at 30 °C, 100 rpm and 0.024 g beads ml−1 of medium, after 12 h of incubation; reaching a degradation rate five times greater than the one obtained in shake flasks (0.415 vs. 0.089 mg−1 h−1, respectively). The system completely removed, with the same efficiency, 50 mg l−1 of BAC for 3 consecutive cycles. These results indicate that the use of Ca-alginate beads containing cells of the consortium can be considered a proper method to achieve degradation of cationic surfactants.

Formation of secondary organic aerosols from the ozonolysis of dihydrofurans Díaz de Mera, Yolanda; Aranda Rubio, Alfonso; Bracco, Larisa Laura Beatriz; Rodríguez, Diana; Rodríguez, Ana In this work we report the study of the ozonolysis of 2,5-dihydrofuran and 2,3-dihydrofuran and the reaction conditions leading to the formation of secondary organic aerosols. The reactions have been carried out in a Teflon chamber filled with synthetic air mixtures at atmospheric pressure and room temperature. The ozonolysis only produced particles in the presence of SO2. Rising relative humidity from 0 to 40% had no effect on the production of secondary organic aerosol in the case of 2,5-dihydrofuran, while it reduced the particle number and particle mass concentrations from the 2,3-dihydrofuran ozonolysis. The water-to-SO2 rate constant ratio for the 2,3-dihydrofuran Criegee intermediate was derived from the secondary organic aerosol (SOA) yields in experiments with different relative humidity values, kH2O/kSO2 = (9.8 ± 3.7) × 10-5. The experimental results show that SO3 may not be the only intermediate involved in the formation or growth of new particles in contrast to the data reported for other Criegee intermediate-SO2 reactions. For the studied reactions, SO2 concentrations remained constant during the experiments, behaving as a catalyst in the production of condensable products. Computational calculations also show that the stabilised Criegee intermediates from the ozonolysis reaction of both 2,5-dihydrofuran and 2,3-dihydrofuran may react with SO2, resulting in the regeneration of SO2 and the formation of low-volatility organic acids.

Desplazamientos paradigmáticos en la filosofía argentina: Del paradigma normalizador a la filosofía de la liberación Aguer, Bárbara; Lucía Belloro Este trabajo forma parte de un proyecto más amplio en el que nos proponemos realizar un recorrido por las principales tradiciones que forjaron la disciplina filosófica en la academia argentina durante la segunda mitad del siglo XX. En este caso en particular realizaremos un doble recorte de este este ambicioso proyecto. Por un lado, nos centraremos en dos paradigmas filosóficos específicos: el paradigma de la normalidad filosófica y el de la filosofía de la liberación. En este sentido, el acento estará puesto en reconstruir los movimientos institucionales y discursivos supuestos en la construcción del paradigma de la normalidad que tramó la emergencia de la profesionalización del campo de la filosofía entre los años 1930 y 1940 y su transformación durante la década de 1970 con la emergencia del movimiento de la filosofía de la liberación. Por otro lado, en un segundo nivel de análisis, consideraremos otras dimensiones específicas para comprender los desplazamientos producidos entre estos paradigmas filosóficos: el rol del/la filósofa/a, la conformación del sujeto filosófico, la concepción de práctica filosófica y la geopolítica del conocimiento (Mignolo, 2010) que cada uno de ellos supone.

Exchange interaction between S = 1/2 centers bridged by multiple noncovalent interactions: Contribution of the individual chemical pathways to the magnetic coupling Pérez, Ana Laura; Neuman, Nicolás Ignacio; Baggio, Ricardo Fortunato; Ramos, Carlos A.; Dalosto, Sergio Daniel; Rizzi, Alberto Claudio; Brondino, Carlos Dante We report EPR and magnetic measurements of diaqua-(pyridine-2,6-dicarboxylato)Copper(II) together with computational calculations. This compound consists of an extended lattice of magnetically equivalent copper(II) ions in which the copper centers are linked by hydrophobic interactions such as π–π, π–metal, and Y–X…π, and hydrogen bonds involving different topologies, viz., [sbnd]Cu[sbnd]Oeq…Oeq[sbnd]Cu[sbnd], [sbnd]Cu[sbnd]Oeq…Oap[sbnd]Cu[sbnd], and [sbnd]Cu[sbnd]Oeq…O[dbnd]C[sbnd]Oeq[sbnd]Cu[sbnd]. The powder EPR spectrum shows nearly axial symmetry with non-resolved hyperfine structure with the copper nucleus, suggesting the presence of intercenter isotropic exchange interactions. Single crystal EPR experiments show a single lorentzian resonance line for all the magnetic field orientations investigated, typical of an extended exchange coupled system. Susceptibility measurements showed weakly antiferromagnetically coupled Cu(II) ions (J = −0.79 (4) cm−1). Using Anderson's exchange narrowing model for the collapse of the hyperfine structure, EPR yielded |J| = 0.6 (1) cm−1. The distinct contributions of the different chemical pathways to the experimentally determined J-value are analyzed through first principle computational calculations.

Oxidative coupling of methane on Sr/La2O3catalysts: Improving the catalytic performance using cordierite monoliths and ceramic foams as structured substrates Sollier, Brenda Maria del Valle; Gómez, Leticia Ester; Boix, Alicia Viviana; Miro, Eduardo Ernesto This work shows how the use of structured catalysts results in an important increase of the C2yield in the oxidative coupling of methane over Sr/La2O3catalysts. Solids with 2 and 5 wt.% of Sr (Sr2 and Sr5) were prepared and washcoated on cordierite monoliths and alumina foams. Homogeneous and mechanically stable catalytic films were obtained in both cases with the addition of silica as binder. Other types of foams were also prepared (aluminum silicate and magnesia stabilized zirconia) but in such cases the adhesion of coatings was rather poor. The catalytic surface XPS characterization of both powders and structured catalysts indicates that lanthanum is mainly present as hydroxide and carbonate and that strontium is mainly present as carbonate. However, in the case of washcoated cordierite monoliths, a modification in La 3d spectra measured by XPS suggests a strong interaction of La with its chemical environment, most probably with silica and/or magnesia. This interaction could be originated by migration of the cordierite components towards the catalytic film, as seen by EDX. The decomposition of La(OH)3and La2O2CO3into La2O3under reaction conditions was confirmed by in situ LRS. While hydroxide prevails at low temperature, the presence of oxycarbonates starts to be relevant when the reaction takes place at temperatures above 400 °C and the oxycarbonates decompose into oxide over 700 °C. The monolithic catalysts (M)Sr2 and (M)Sr5 resulted twofold more active towards ethane and ethylene than the corresponding Sr2 and Sr5 powders. Meanwhile, the washcoated alumina foam (FAl)Sr5 showed methane conversion values similar to those of the powder but higher C2selectivity; thus, the C2yield was also higher. In the case of the monolithic catalysts, the increase in methane conversion and C2yield could be related to the interaction of Sr and La with silica and/or magnesia present in the cordierite structure. In the case of the alumina foam catalyst, the higher selectivity could be originated by the lower gas phase/catalytic surface ratio (as compared with the monolith), that inhibits gas-phase combustion of C2products. In order to assess the stability of (M)Sr5, which was the best catalyst among the ones studied in this work, time-on stream runs at 600 and 800 °C were performed. Surprisingly, at 800 °C, the C2yield steeply increased from 18% to 22.5% during the first 70 h and then remained constant until 100 h. This phenomenon could be due to a gradual increase in chemical interactions between the cordierite components and the catalytic coat. At lower temperature (600 °C), C2yield was constant during the 100 h of time-on-stream, indicating that this temperature is not enough to produce the said effect.

Bycatch of the Southern King Crab (Lithodes santolla) in the Patagonian shrimp fishery in the Southwestern Atlantic Ocean. Can it contribute to the depletion of its population? Varisco, Martin Alejandro; Cochia, Pablo; Góngora, María Eva; Bovcon, Nelson Darío; Balzi, Pamela; Vinuesa, Julio Hector The Southern King Crab (SKC), Lithodes santolla, has supported a growing fishery in San Jorge Gulf (Patagonia, Argentina) since 2011. This fishery is developed by vessels called crabbers. SKC is also caught as bycatch in the Patagonian shrimp fishery, a major crustacean fishery in the Southwestern Atlantic Ocean. In this work, we characterized SKC bycatch in shrimp fishery and compared 1994–1996 data (which reflected little fishing impact) and 2011–2012 data (at the beginning of the current SKC fishery by crabbers in San Jorge Gulf), to determine the particular effects of bycatch on the SKC population. The frequency of occurrence of SKC in shrimp hauls was 84.08%. However, the relative abundance was low, in most of the hauls SCK represented less than 5% of the capture. Between 2006 and 2011, the estimated SKC bycatch was 2432 tn/year. Frequency of occurrence and abundance were higher in the same area where crabbers operate. SKC bycatch is commonly discarded, but, in 18% of the hauls, SKC are processed on board, although this is illegal. Mortality estimated at the beginning of handling was 19%, but this value may be greater due to the long time of onboard handling. SKC bycatch include critic stages of its life cycle such as juveniles, ovigerous females and molting individuals. Juveniles represented 26.9% of the total SKC bycatch, while ovigerous females represented 28.1%. Sex ratios and male size showed no differences between 1994–1996 and 2011–2012, whereas the proportion of ovigerous females decreased between both periods. This decrease can be related to the interference of trawlings in their reproductive migration to coastal waters or in their mating grounds. We consider that the main problem of SKC bycatch is the detrimental effects on its reproductive potential due to the increase in the proportion of non-ovigerous females and the mortality of ovigerous females along with extensive handling, which can also result in a significant egg loss.

Role of Mitochondrial Metabolism in the Control of Early Lineage Progression and Aging Phenotypes in Adult Hippocampal Neurogenesis Beckervordersandforth, Ruth; Ebert, Birgit; Schäffner, Iris; Moss, Jonathan; Fiebig, Christian; Shin, Jaehoon; Moore, Darcie L.; Ghosh, Laboni; Trinchero, Mariela Fernanda; Stockburger, Carola; Friedland, Kristina; Steib, Kathrin; von Wittgenstein, Julia; Keiner, Silke; Redecker, Christoph; Hölter, Sabine M.; Xiang, Wei; Wurst, Wolfgang; Jagasia, Ravi; Schinder, Alejandro Fabián; Ming, Guo-li; Toni, Nicolas; Jessberger, Sebastian; Song, Hongjun; Lie, D. Chichung Precise regulation of cellular metabolism is hypothesized to constitute a vital component of the developmental sequence underlying the life-long generation of hippocampal neurons from quiescent neural stem cells (NSCs). The identity of stage-specific metabolic programs and their impact on adult neurogenesis are largely unknown. We show that the adult hippocampal neurogenic lineage is critically dependent on the mitochondrial electron transport chain and oxidative phosphorylation machinery at the stage of the fast proliferating intermediate progenitor cell. Perturbation of mitochondrial complex function by ablation of the mitochondrial transcription factor A (Tfam) reproduces multiple hallmarks of aging in hippocampal neurogenesis, whereas pharmacological enhancement of mitochondrial function ameliorates age-associated neurogenesis defects. Together with the finding of age-associated alterations in mitochondrial function and morphology in NSCs, these data link mitochondrial complex function to efficient lineage progression of adult NSCs and identify mitochondrial function as a potential target to ameliorate neurogenesis-defects in the aging hippocampus.

A PLL-based resampling technique for vibration analysis in variable-speed wind turbines with PMSG: A bearing fault case Pezzani, Carlos Martín; Bossio, Jose Maria; Castellino, Ariel Matías; Bossio, Guillermo Rubén; de Angelo, Cristian Hernan Condition monitoring in permanent magnet synchronous machines has gained interest due to the increasing use in applications such as electric traction and power generation. Particularly in wind power generation, non-invasive condition monitoring techniques are of great importance. Usually, in such applications the access to the generator is complex and costly, while unexpected breakdowns results in high repair costs. This paper presents a technique which allows using vibration analysis for bearing fault detection in permanent magnet synchronous generators used in wind turbines. Given that in wind power applications the generator rotational speed may vary during normal operation, it is necessary to use special sampling techniques to apply spectral analysis of mechanical vibrations. In this work, a resampling technique based on order tracking without measuring the rotor position is proposed. To synchronize sampling with rotor position, an estimation of the rotor position obtained from the angle of the voltage vector is proposed. This angle is obtained from a phase-locked loop synchronized with the generator voltages. The proposed strategy is validated by laboratory experimental results obtained from a permanent magnet synchronous generator. Results with single point defects in the outer race of a bearing under variable speed and load conditions are presented.

¿Heredada o construida? Diferentes perspectivas de análisis de la identidad étnica entre los descendientes de inmigrantes en Argentina; Inherited or Constructed? The Different Perspectives of Analysis of Ethnic Identity among Polish Immigrants’ Descendants in Argentina Porada, Katarzyna La comunidad polaca en Argentina es resultado de movimientos poblacionales a gran escala, iniciados en el siglo XIX y finalizados en la segunda mitad del XX. Han pasado ya varias décadas desde que prácticamente se detuvieron los procesos migratorios entre ambos países. Pese a la distancia temporal que separa la llegada del último grupo inmigrante, algunos de sus descendientes, que nacieron, crecieron y fueron educados en Argentina, siguen conservando, de una u otra forma, los lazos que les vinculan con el lugar de nacimiento de sus antepasados. El presente artículo analiza cómo, en el contexto actual, los descendientes de inmigrantes polacos perciben su identidad étnica, cuáles son las particularidades de los lazos, reales o simbólicas, que mantienen con el país de origen de sus antepasados y qué es lo que les motiva a lo hora de conservar esta vinculación.; The Polish community in Argentina is the result of large-scale population movements that began in the 19th century and completed in the second half of the 20th. Several decades have passed since that migration between the two countries stopped. Despite the time elapsed since the arrival of the last immigrant group, some of their descendants, who were born, grew up and were educated in Argentina, still maintain, in one way or anot-her, the ties that bind them to the birthplace of their ancestors. This article, using different theoretical perspectives, analyzes how, in the current context, the descendants of Polish immigrants perceive their ethnic identity, what the characteristics of the links, real or sym-bolic, they have with the country of their ancestors are and what motivates them to preserve this linkage.

El par cómico en la comedia temprana de Aristófanes y su pervivencia en Lisístrata; The comic couple in Aristophanes’ early comedy and its survival in Lisistrata Schere, María Jimena La noción de par cómico, definida como un par tópico compuesto por dos personajes opuestos y antagónicos, constituye una clave fundamental para comprender la comedia temprana de Aristófanes. Este esquema binario domina en las primeras comedias conservadas del autor y se vuelve a implementar en su forma más convencional en Lisístrata. Su utilización en Lisístrata se debe, entre otros motivos, al hecho de que esta pieza retoma la virulencia satírica de las primeras obras y la polémica a favor de la paz con Esparta, tema presente en todas las comedias tempranas conservadas.; A noção de par cómico, definida como um par tópico composto por duas personagens opostas e antagónicas, constitui uma chave fundamental para compreender a comédia inicial de Aristófanes. Este esquema binário domina nas primeiras comédias conservadas do autor e volta a implementar-se na sua forma mais convencional na Lisístrata: A sua utilização na Lisístrata deve-se, entre outros motivos, ao facto de esta peça retomar a virulência satírica das primeiras obras e a polémica a favor da paz com Esparta, tema presente em todas as comédias iniciais conservadas.; The notion of comic couple, understood as a conventional couple formed by two opposite and antagonistic characters, provides a fundamental key to understand Aristophanes’ early comedy. This binary scheme is prevalent in the author’s early extant comedies and will again be implemented in its more conventional form in Lisistrata. Its occurrence in Lisistrata is due, among other causes, to the fact that this play resumes the tone of satirical virulence present in the early plays and the controversy in favour of peace with Sparta, a theme which resonates in all of the author’s early extant plays.; La notion de duo comique, conçue comme un duo topique composé par deux personnages opposés et antagoniques, constitue une clé fondamentale pour comprendre la comédie initial d’Aristophane. Ce schéma binaire domine dans les premières comédies préservées de l’auteur et se remet en oeuvre dans sa forme la plus conventionnelle dans Lysistrata. Son utilisation dans Lysistrata est due, entre autre raison, au fait que cette pièce reprend la virulence satyrique des premières oeuvres et la polémique en faveur de la paix avec Sparte, thème présent dans toutes les comédies initiales préservées.

The crystal structure of PknI from Mycobacterium tuberculosis shows an inactive, pseudokinase-like conformation Lisa, María Natalia; Wagner, Tristan; Alexandre, Matthieu; Barilone, Nathalie; Raynal, Bertrand; Alzari, Pedro M.; Bellinzoni, Marco Eukaryotic-like Ser/Thr protein kinases (ePKs) have been identified in many bacterial species, where they are known to mediate signalling mechanisms that share several features with their eukaryotic counterparts. In Mycobacterium tuberculosis, PknI is one of the 11 predicted ePKs and it has been related to bacterial virulence. In order to better understand the molecular basis of its role in mycobacterial signalling, we solved the crystal structure of the PknI cytoplasmic domain. We found that even though PknI possesses most conserved elements characteristic of Hanks-type kinases, it is degraded in several motifs that are essential for the ePKs catalytic activity. Most notably, PknI presents a remarkably short activation segment lacking a peptide–substrate binding site. Consistent with this observation and similar to earlier findings for eukaryotic pseudokinases, no kinase activity was detected for the catalytic domain of PknI, against different substrates and in various experimental conditions. Based on these results, we conclude that PknI may rely on unconventional mechanism(s) for kinase activity and/or it could play alternative role(s) in mycobacterial signalling. Database: Atomic coordinates and structure factors for the catalytic domain of M. tuberculosis PknI are in the Protein Data Bank under the accession codes 5M06 (wild-type PknI + ADP), 5M07 (PknI_C20A), 5M08 (PknI_C20A_R136A) and 5M09 (PknI_C20A_R136N).