Observaciones sobre las transferencias léxicas del inglés en español bonaerense Hipperdinger, Yolanda Haydee En español bonaerense, numerosos préstamos de lenguas europeas se han incorporado al acervo léxico en los dos últimos siglos, como concomitantes lingüísticos de diversos fenómenos culturales. La última lengua con un rol donante de relevancia es el inglés, como en el caso de muchas otras variedades lingüísticas en el mundo. En este artículo analizamos algunos de los emergentes del influjo del inglés en español bonaerense, particularmente a nivel léxico. En primer lugar, sobre la base de nuestros registros nos ocupamos de revisar algunas correlaciones que comúnmente se dan por supuestas (entre la extensión de uso y la adaptación a la lengua recipiente, entre los usos orales y escritos de los mismos lexemas de préstamo, entre la permanencia en uso de un préstamo y la fijación del modo en que se lo realiza oralmente y/o se lo representa grafémicamente, entre la fijación y la adaptación). Seguidamente nos ocupamos de analizar instancias de hipercorrección, que transparentan la íntima relación entre los usos y las actitudes, tanto como el papel rector que sobre estas últimas ejerce el prestigio de la lengua donante (aun cuando se combine con un conocimiento insuficiente de la misma). Por último, dejamos constancia de usos en los que se verifica una especial posición modélica del inglés, ya que también a sus pautas (además de a las españolas nativas) recurren en ocasiones los hablantes de la región, tanto para la realización de incorporaciones de otras lenguas cuanto para algunas innovaciones creativas.; In the Spanish variety spoken in Buenos Aires, many loanwords from European languages have been incorporated to its lexical store in the last two centuries, as linguistic consequences of different cultural phenomena. The last language with a donor role of significance is English, as in case of lots of other linguistic varieties all over the world. In this article we analyze some of the resultants of the influence of English on Buenos Aires’ Spanish, particularly at the lexical level. Firstly, on the basis of our registers we revise some correlations that are commonly taken for granted (between use extension and adaptation to the recipient language, between oral and written uses from the same borrowed lexemes, between the permanence in use of a loanword and the fixation with which it is orally realized and/or it is graphemically represented, between fixation and adaptation). Secondly, we analyze hypercorrection requests, that clearly show the intimate relationship between uses and attitudes, as well as the guiding role that the prestige of the donor language exerts over the latter (even when it is combined with an insufficient knowledge of it). Lastly, we lend evidence of uses in which a special model position of English is verified, because sometimes regional speakers also fall back on its patterns (as well as on their native Spanish ones) for the realization of other languages’ incorporations or for some creative innovations.

Few-electron semiconductor quantum dots with Gaussian confinement Gomez, Sergio Santiago; Romero, Rodolfo Horacio We have performed Hartree-Fock calculations of the electronic structure of N ≤ 10 electrons in a quantum dot modeled with a confining Gaussian potential well. We discuss the conditions for the stability of N bound electrons in the system. We show that the most relevant parameter determining the number of bound electrons is V 0 R 2. Such a feature arises from widely valid scaling properties of the confining potential. Gaussian Quantum dots having N = 2, 5, and 8 electrons are particularly stable in agreement with the Hund rule. The shell structure becomes less and less noticeable as the well radius increases.

Trypanosoma cruzi: adaptation to its vectors and its hosts Noireau, François; Diosque, Patricio; Jansen, Ana María American trypanosomiasis is a parasitic zoonosis that occurs throughout Latin America. The etiological agent, Trypanosoma cruzi, is able to infect almost all tissues of its mammalian hosts and spreads in the environment in multifarious transmission cycles that may or not be connected. This biological plasticity, which is probably the result of the considerable heterogeneity of the taxon, exemplifies a successful adaptation of a parasite resulting in distinct outcomes of infection and a complex epidemiological pattern. In the 1990s, most endemic countries strengthened national control programs to interrupt the transmission of this parasite to humans. However, many obstacles remain to the effective control of the disease. Current knowledge of the different components involved in elaborate system that is American trypanosomiasis (the protozoan parasite T. cruzi, vectors Triatominae and the many reservoirs of infection), as well as the interactions existing within the system, is still incomplete. The Triatominae probably evolve from predatory reduvids in response to the availability of vertebrate food source. However, the basic mechanisms of adaptation of some of them to artificial ecotopes remain poorly understood. Nevertheless, these adaptations seem to be associated with a behavioral plasticity, a reduction in the genetic repertoire and increasing developmental instability.

Acción, conocimiento y dolo eventual Manrique, Maria Laura En este trabajo señalo algunos desafíos que genera el dolo eventual a una explicación humeana de la acción. Estos desafíos son de dos clases: problemas internos y problemas externos. En cuanto a los problemas internos de la teoría del dolo eventual muestro que una teoría reduccionista o epistémica del dolo se compromete con dar una respuesta negativa a la pregunta sobre la diferencia entre dolo eventual y culpa consciente. Si por el contrario, se acepta un enfoque no reduccionista, no se puede dar cuenta de que el dolo eventual es genuinamente dolo sin alterar los términos de su propia teoría. Este esfuerzo presiona para modificar la teoría en una versión normativizada del dolo. La consecuencia de ello es la separación del dolo con los estados mentales que efectivamente posee el agente, borrando así la diferencia entre responsabilidad por las acciones y responsabilidad por las consecuencias. En cuanto a los inconvenientes de adecuación externa sostendré que la figura del dolo eventual invierte la prioridad conceptual de la explicación sobre la evaluación de las acciones responsabilizando a los agentes por las consecuencias que ocasionaron y no por lo que hicieron.; In this paper the author points out some problems that stem from the connection between contemporary theories in criminal law about dolus eventualis, and our paradigmatic conception of action, i.e. the so called Humean theory. These problems are of two classes: internal and external ones. On the one hand, the author shows that reductionist theories are not able to provide a sound criterion for distinguishing between dolus eventualis and conscious negligence. If reductionist theories are rejected, dolus eventualis can not be regarded as a genuine form of dolus. In order to overcome this problem, criminalists often replace a descriptive point of view on the actual motivation of agents for an adscriptive (normative) conception of dolus, but this shift separates dolus from agents' mental states that determine their actions. As a consequence of this conceptual movement, differences between subjective and objective responsibility actually vanish. On the other hand, the author shows that contemporary theories challenge the conceptual priority of the explanation of actions over their evaluation. Thus, these theories make agents responsible on account of the consequences of their actions rather than by their actions.

Acceleration of Monte Carlo modeling of light transport in turbid media; an approach based on hybrid, theoretical and numerical, calculations Di Rocco, Hector Omar; Iriarte, Daniela Ines; Pomarico, Juan Antonio; Ranea Sandoval, Hector Francisco A novel method to accelerate Monte Carlo (MC) simulations of photon migration in turbid media is presented. It is specifically suited for transillumination studies in slab geometries including some deep inhomogeneity. Propagation up to the inhomogeneity, at a given depth S1, is replaced by theoretical calculations using well established models. Then, photon propagation is continued inside the complete slab using MC rules until detection or absorption occurs. We report improvements in speed in factors up to approximately 10; the deeper the inhomogeneity, the larger the improvement. Examples are given showing that information remains unchanged with respect to pure MC simulations.

Evaluation of chlorine, benzalkonium chloride and lactic acid as sanitizers for reducing Escherichia coli O157:H7 and Yersinia enterocolitica on fresh vegetables Velázquez, Lidia del Carmen; Barbini, Norma Beatriz; Escudero, María Esther; Lucero Estrada, Cecilia Stella Marys; Stefanini de Guzman, Ana Maria Teresa Valentina The effectiveness in the assurance of fresh vegetable microbiological quality of wash solutions containing 200 ppm free chlorine, 0.1 mg/ml benzalkonium chloride, 0.2% and 1% lactic acid was assessed on Escherichia coli O157:H7 and Yersinia enterocolitica contaminated lettuce and tomatoes. Y. enterocolitica reduction on tomatoes (5.08, 4.77 and 4.21 log after 0.2% lactic acid, 200 ppm chlorine and 0.1 mg/ml benzalkonium chloride treatments, respectively) were significantly higher than those for Y. enterocolitica on lettuce and E. coli O157:H7 on both vegetables. Antimicrobial treatment effects on bacterial counts and product quality after subsequent 7 day storage (4 C and 22 C) were determined. No pathogens were found in natural microflora of fresh vegetables.

Caracterización de productos co-cristalizados de sacarosa mediante Rayos X y DSC Deladino, Lorena; Navarro, Alba Sofia del Rosario; Martino, Miriam Nora The objective of the work was to characterize through X-rays, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), co-crystallized products within a sucrose matrix. These products contained mineral salts, ca1ciumlactate, magnesium suIphate and a lyophilized yerba mate extract (Ilex paraguariensis). The studied techniques allowed comparing the structure ofthe different products and the hydration state of the salts after the process. The co-crystallized products showed the basic crystalline structure of control sample of sucrose. In the case of the minerals, dehydration was not totally accomplished since different salt hydrate structures were detected.

Synthesis and anticonvulsant activity of amino acid-derived sulfamides Gavernet, Luciana; Elvira, Juan E.; Samaja, Gisela Anabel; Pastore, Valentina; Cravero, Mariana Sella; Enrique, Andrea Verónica; Estiu, Guillermina Lucia; Bruno Blanch, Luis Enrique Sulfamides are promising functions for the design of new antiepileptic drugs (Bioorg. Med. Chem. 2007, 15, 1556-1567; 5604-5614). Following previous research in this line, a set of amino acid-derived sulfamides has been designed, synthesized, and tested as new anticonvulsant compounds. The experimental data confirmed the ability of some of the structures to suppress the convulsions originated by the electrical seizure (MES test) at low doses (100 mg/kg).

'Durable Residues': Addressing the use of microwear, a case study from March Hill Briz Godino, Ivan; Alvarez, Myrian Rosa; Spikins, Penny; Needham. Andrew Different cultural and research traditions have led to distinctively different approaches tolithics analysis. An integration of different approaches can often give new ´ways ofseeing´ artefact assemblages and distribution patterns and provide valuable insights intopast activities. Here we present the preliminary results of a project integrating detailedanalytical techniques, focused on processes of production and consumption and socialdynamics in ethnarchaeological contexts in Tierra del Fuego with existing detailed lithicanalysis at Mesolithic sites in the Central Pennines. Such methods, taken fromArgentina (Álvarez) and Spain (Briz), that were developed in ethnoarchaeologicalcontexts employed detailed edge morphological analysis and use wear. When appliedto site A at March Hill, these techniques yielded interesting new insights about activitiesat the site, and provided a test case for such techniques.

Rotigotine transdermal delivery for the treatment of Parkinson's disease Rascol, Olivier; Perez Lloret, Santiago Background: Rotigotine is a non-ergot dopamine agonist that has been developed as a new transdermal formulation, and is indicated for use in early (USA and Europe) and advanced (Europe only) Parkinson's disease (PD). The potential advantages of the rotigotine patch include immediacy of effect onset as intestinal absorption in unneeded, constant drug delivery, and ease of use via application of a once-daily adhesive patch. An interesting element of this profile is constant drug delivery, which may avoid pulsatile dopaminergic stimulation, which has been postulated to be related to the development of motor complications. Objective: To consider the evidence surrounding the profile of rotigotine and, in particular, whether its constant delivery system offers significant benefits to the treatment of early and advanced PD. Methods: Source material was identified using a PubMed search for the term 'rotigotine' (up to March 2008). The review focuses only on publications related to the rotigotine indication for PD. Results/conclusion: The rotigotine transdermal patch demonstrates clinical efficacy, alongside a tolerability profile that appears to be well within the range of that observed with other non-ergot dopamine agonists. The once-daily patch formulation may favour compliance but, in similarity with the other theoretical advantages of constant drug delivery (for example reduced emergence of motor complications, improved tolerance to peripheral AEs), requires further detailed study.

Aminoguanidine impedes human pancreatic tumor growth and metastasis development in nude mice Mohamad, Nora Alicia; Criocco, Graciela P.; Sambuco, Lorena Andrea; Croci, Máximo; Medina, Vanina Araceli; Gutiérrez, Alicia Susana; Bergoc, Rosa Maria; Rivera, Elena Susana; Martín, Gabriela A. Aim: To study the action of aminoguanidine on pancreatic cancer xenografts in relation to cell proliferation, apoptosis, redox status and vascularization. Methods: Xenografts of PANC-1 cells were developed in nude mice. The animals were separated into two groups: control and aminoguanidine treated. Tumor growth, survival and appearance of metastases were determined in vivo in both groups. Tumors were excised and ex vivo histochemical studies were performed. Cell growth was assessed by Ki-67 expression. Apoptosis was studied by intratumoral expression of B cell lymphoma-2 protein (Bcl-2) family proteins and Terminal deoxynucleotidyl transferase biotin-dUTP Nick End Labeling (Tunel). Redox status was evaluated by the expression of endothelial nitric oxide synthase (eNOS), catalase, copper-zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD) and glutathione peroxidase (GPx). Finally, vascularization was determined by Massons trichromic staining, and by VEGF and CD34 expression. Results: Tumor volumes after 32 d of treatment by aminoguanidine (AG) were significantly lower than in control mice (P < 0.01). Median survival of AG mice was significantly greater than control animals (P < 0.01). The appearance of both homolateral and contralateral palpable metastases was significantly delayed in AG group. Apoptotic cells, intratumoral vascularization (trichromic stain) and the expression of Ki-67, Bax, eNOS, CD34, VEGF, catalase, CuZnSOD and MnSOD were diminished in AG treated mice (P < 0.01), while the expression of Bcl-2 and GPx did not change. Conclusion: The antitumoral action of aminoguanidine is associated with decreased cell proliferation, reduced angiogenesis, and reduced expression of antioxidant enzymes.

Biología reproductiva de la serpiente semiacuática Liophis semiaureus (Serpentes, Colubridae) en el nordeste de Argentina Lopez, Maria Soledad; Giraudo, Alejandro Raul; Arzamendia, Vanesa; Chiaraviglio, Margarita Las serpientes tienen una notable flexibilidad y diversidad en sus tácticas reproductivas, a pesar de ello, los estudios acerca de la biología reproductiva de especies sudamericanas en zonas subtropicales-templadas son escasos. Se analizó la biología reproductiva de Liophis semiaureus en el nordeste de Argentina, incluyendo la madurez y dimorfismo sexual, fecundidad y ciclo reproductivo. Las hembras maduras fueron significativamente más largas, presentaron mayor peso corporal y alcanzaron la madurez sexual a una longitud mayor que los machos. Los machos tuvieron colas más largas que las hembras. El ciclo reproductivo fue estacional con mayor actividad en los períodos templados del año aunque previos a la época de inundaciones. Liophis semiaureus invirtió más energía en la reproducción que en el crecimiento, lo que posibilita que comiencen a reproducirse con tamaños más pequeños con respecto a otras poblaciones, sin retrasar su reproducción hasta alcanzar mayores tamaños. Esta puede ser una estrategia ventajosa en climas estacionales. Las características reproductivas y de dimorfismo sexual en L. semiaureus se encontrarían influenciadas por aspectos filogenéticos, geográficos y ecológicos, lo que determina que la especie responda de manera general al patrón reproductivo del grupo taxonómico pero con particularidades propias determinadas por los factores geográficos y los requerimientos ecológicos.

Diversification of inflorescence development in The PCK clade (Poaceae: Panicoideae: Paniceae) Reinheimer, Renata; Zuloaga, Fernando Omar; Vegetti, Abelardo Carlos; Pozner, Raúl Ernesto In grasses, inflorescence diversification and its correlation with species evolution are intriguing and not well understood. Part of this problem lies in our lack of comprehension about the inflorescence morphological complexity of grasses. We focused our study on the PCK clade (named for phosphoenol pyruvate carboxykinase), a well‐supported monophyletic group for which the relationships among its taxa are not well resolved. Interestingly, the PCK clade has an extensive diversity of adult inflorescence forms. A comparative developmental approach can help us to understand the basis of such morphological differences as well as provide characters that can be used in phylogenetic studies of the group. Using SEM studies, we demonstrate that inflorescence morphology in this clade is even more complex than what is typically observed in adult forms. We describe a number of new characters, and some classical features previously used for taxonomic purposes are redefined on the basis of development. We also define four morphological groups combining adult inflorescence form and development, and we discuss some of the evolutionary aspects of inflorescence diversification in the PCK clade. Taxonomic delimitation among genera in the PCK clade remains confusing and unclear where molecular and morphological studies support different classifications.

Isolation of salmonella typhimurium from dead blue and gold macaws (ara ararauna); Aislamiento de Salmonella typhimurium a partir de guacamayas azul y amarillo (Ara ararauna) muertas Vigo, Germán Blás; Origlia, Javier Anibal; Gornatti Churria, Carlos Daniel; Piscopo, Miguel Victor; Salve, Angela; Caffer, María I.; Pichel, Mariana; Binsztein, Norma; Leotta, Gerardo Anibal Dos polluelos de guacamayas azul y amarillo (Ara ararauna) murieron por una salmonelosis fatal en la Provincia de Buenos Aires, Argentina. Las aves se examinaron por histopatología y microbiología. La Salmonella enterica subespecies enterica serovar Typhimurium fue aislada de hígado, bazo, corazón, pulmón, riñón e intestino de ambas aves. Todas las cepas fueron susceptibles a ampicilina, cefalotina, cefotaxima, enrofloxacina, ácido nadilixico, gentamicina, estreptomicina, cloranfenicol, fosfomicina, tetraciclina, nitrofurantoina y la combinación trimetoprim-sulfametoxazol. El perfil XbaI de la Salmonella Typhimurium aislada de los dos animales que compartían la misma jaula fueron idénticos mediante electroforesis en gel de campos pulsantes (por sus siglas en inglés PFGE), y mostraron un patrón único comparado con 301 aislamientos que están incluidos en la base de datos nacional de patrones de PFGE de Salmonella, denominada PulseNet. Este es el primer reporte que describe casos fatales de salmonelosis en guacamayas azul y amarillo.; Two blue and gold macaw (Ara ararauna) chicks died of fatal salmonellosis in Buenos Aires Province, Argentina. The birds were histopathologically and microbiologically examined. Salmonella enterica subspecies enterica serovar Typhimurium was isolated from the liver, spleen, heart, lung, kidney, and intestine of both birds. All strains were susceptible to ampicillin, cephalothin, cefotaxime, enrofloxacin, nalidixic acid, gentamicin, streptomycin, chloramphenicol, fosfomycin, tetracycline, nitrofurantoin, and trimethoprim-sulfamethoxazole. The XbaI-PFGE profile of the Salmonella Typhimurium isolated from the two animals, which shared the same cage, was identical and showed a unique pattern compared with 301 isolates included in the PulseNet national database of Salmonella pulsed-field gel electrophoresis patterns. This is the first report that describes fatal cases of salmonellosis from blue and gold macaws.

Likelihood-Based Sufficient Dimension Reduction Cook, R. Dennis; Forzani, Liliana Maria We obtain the maximum likelihood estimator of the central subspace under conditional normality of the predictors given the response. Analytically and in simulations we found that our new estimator can preform much better than sliced inverse regression, sliced average variance estimation and directional regression, and that it seems quite robust to deviations from normality.

Design of multiproduct batch plants with units in series including process performance models Moreno, Marta Susana; Iribarren, Oscar Alberto; Montagna, Jorge Marcelo This work deals with the simultaneous optimization of process decision variables and the structure of multiproduct batch plants considering the duplication of units in series to perform a given unit operation. Performance process models allow expressing the size and time factors of the posynomial formulation as a function of the process variables with the highest impact on costs. They are added into the design problem and handled as extra constraints. Structural alternatives for the plant were defined in order to include the duplication of units in series. Thus, the problem is formulated as an optimization problem, using mixed integer nonlinear programming to minimize the total cost of the process, subjected to design specifications. The model application is illustrated with a process for the production of oleoresins. The convenience of including the duplication in series together with process variables in process optimization is tested through the resolution of various problem cases.

Liquid-Glassy Polymer Interphases: Diffusion Kinetics in Conditions of Unlimited Liquid Supply Tomba, Juan Pablo; Carella, Jose Maria; Pérez, Claudio Javier; Pastor, José M. We investigate evidences of diffusion controlled by mechanical relaxation of the glassy matrix, i.e. Case-II mechanism, in a series of liquid/glassy interphases formed by polystyrene (PS) and poly (phenylene oxide) (PPO) as liquid and glassy components respectively. Diffusion experiments were performed in conditions of unlimited supply of the liquid polymer, parallel to those in which Case-II has been effectively verified. Interphase profiles were obtained via optical sectioning with confocal Raman microspectroscopy. We observed that interphase diffusion kinetics were markedly Fickean, in contrast with interpretations from other authors that invoke Case-II to explain the mechanisms that rule interphase evolution in these systems. 

The correlation contracted schrodinger equation: An accurate solution of the G-particle-hole hypervirial Alcoba, Diego Ricardo; Valdemoro, C.; Tel, L. M.; Pérez-Romero, E. The equation obtained by mapping the matrix representation of the Schrödinger equation with the 2nd-order correlation transition matrix elements into the 2-body space is the so called correlation contracted Schrödinger equation (CCSE) (Alcoba, Phys Rev A 2002, 65, 032519). As shown by Alcoba (Phys Rev A 2002, 65, 032519) the solution of the CCSE coincides with that of the Schrödinger equation. Here the attention is focused in the vanishing hypervirial of the correlation operator (GHV), which can be identified with the anti-Hermitian part of the CCSE. A comparative analysis of the GHV and the anti-Hermitian part of the contracted Schrödinger equation (ACSE) indicates that the former is a stronger stationarity condition than the latter. By applying a Heisenberg-like unitary transformation to the G-particle-hole operator (Valdemoro et al., Phys Rev A 2000, 61, 032507), a good approximation of the expectation value of this operator as well as of the GHV is obtained. The method is illustrated for the case of the Beryllium isoelectronic series as well as for the Li2 and BeH2 molecules. The correlation energies obtained are within 98.80-100.09% of the full-configuration interaction ones. The convergence of these calculations was faster when using the GHV than with the ACSE. © 2009 Wiley Periodicals, Inc.

DFT Calculations of the Molecular Force Field of Vanadyl Nitrate, VO(NO3)3 Brandan, Silvia Antonia; Socolsky, Cecilia; Ben Altabef, Aída A structural and vibrational theoretical study for vanadyl nitrate was carried out. The Density Functional Theory (DFT) has been used to study vibrational properties. The structures were fully optimized at the B3LYP/6-31G *, B3LYP/6-311G *, and B3LYP/6-311 + G * levels of theory and the harmonic vibrational frequencies were evaluated at the same level. The calculated harmonic vibrational frequencies for vanadyl nitrate are consistent with their experimental IR and Raman spectra in gas and liquid phases. Through these calculations a precise knowledge of the normal modes of vibration was obtained, considering the coordination mode adopted by the nitrate group in the mirror plane as monodentate and bidentate. A total assignment of the observed bands in the vibrational spectra for vanadyl nitrate is proposed in this work. The nature of the V-O and V←O bonds in the compound was systematically and quantitatively investigated by means of the Natural Bond Order (NBO) analysis. The topological properties of the electronic charge density were analyzed employing Bader's Atoms in Molecules theory (AIM).

Temporal variation in abundance and fecundity of the invading copepod Eurytemora americana in Bahia Blanca Estuary during an unusual year Berasategui, Anabela Anhi; Hoffmeyer, Monica Susana; Biancalana, Florencia; Fernandez Severini, Melisa Daiana; Menendez, Maria Clara Temporal change of biotic and environmental variables was corroborated by a Mann–Whitney/Kruskal–Wallis non-parametric tests, with significant differences ( p 0.01) in all variables throughout the study. Abundance population results showed very high values in relation to those recorded in recent years in Bahı ́ a Blanca Estuary. This response could be due to the unusual combination of environmental factors (polar wave with temperatures 6 C and a drought period with high salinities, 32.7–36.6) recorded during the studied winter period. Significant positive correlations between abundance and salinity ( p < 0.01, n = 226), and hatching success ( p < 0.01, n = 25) as well as a significant negative correlation between abundance and chlorophyll a ( p < 0.01, n = 226) were found. Although E. americana shows a k-strategy within its annual pulse, it presented two markedly distinct behaviours depending on temporal environmental variability. From July to early september, when the estuary evidenced high salinity, low temperature and high food availability, E. Americana showed large females, large clutch size and high hatching success. When environmental conditions became unfavorable from September to October, small females, small clutch size and very low hatching success were observed. The latter is associated with diapause egg laying which ensures pop- ulation recruitment. According to our findings the particular combination of low temperatures, high salinities and high available food (i.e. variables which each year modulate its pulse) during 2007 winter– spring, favored the great development of E. americana . This invading species in its opportunistic role has managed to exploit a vacant niche in the estuary, developing two different behaviours within the k-strategy depending on change in environmental conditions.