Mollusk communities differ between microenvironments within a shallow lake in the Pampean Region, Argentina

El objetivo de este trabajo es comparar la distribución de los ensambles de moluscos en diferentes sitios dentro de un lago somero pampeano y evaluar la relación que existe entre la abundancia y la riqueza de moluscos y las variables ambientales. Los moluscos mostraron una distribución en parches, pero no azarosa. Tres de los sitios que eran más profundos y que estaban dominados por macrófitas emergentes estuvieron caracterizados por mayores abundancias de los gasterópodos Heleobia parchappii, Physa acuta y Uncancylus concentricus. En contraste, los otros dos sitios que estuvieron caracterizados por menores profundidades, menores pH, mayor diversidad de vegetación y temperaturas del agua más altas estuvieron dominados por Biomphalaria peregrina y por el bivalvo Musculium argentinum. Este estudio evidencia la distribución en parches de moluscos dulceacuícolas en lagos someros de la ecorregión pampeana donde las variables ambientales explican de forma parcial la distribución local dentro del lago.The aim of this study is to compare the faunistic mollusk composition at a local scale, in different sites within a shallow lake, and to evaluate the relation between abundance and richness of mollusks and the environmental variables. The distribution of the mollusks within the water body was patchy but not random. Three of the sites were deeper, mainly dominated by emergent macrophytes and were characterized by the dominance of the gastropods Heleobia parchappii, Physa acuta and Uncancylus concentricus. In contrast, the other two sites were dominated by Biomphalaria peregrina and the bivalve Musculium argentinum, and were characterized by lower depth and pH, and higher vegetation diversity and water temperature. This study evidences the patchiness of freshwater mollusk species in a Pampean shallow lake, where environmental factors partially explain the local distribution within the lake

Enhancement of photoacoustic detection of inhomogeneities in polymers

We report a series of experiments on laser pulsed photoacoustic excitationin turbid polymer samples addressed to evaluate the sound speed in the samples and the presence of inhomogeneities in the bulk. We describe a system which allows the direct measurement of the speed of the detected waves by engraving the surface of the piece under study with a fiduciary pattern of black lines. We also describe how this pattern helps to enhance the sensitivity for the detection of an inhomogeneity in the bulk. These two facts are useful for studies in soft matter systems including, perhaps, biological samples. We have performed an experimental analysis on Grilon(R) samples in different situations and we show the limitations of the method.Comment: 8 pages, 7 figure

Electrical studies and plasma characterization of an atmospheric pressure plasma jet operated at low frequency

Low-temperature, high-pressure plasma jets have an extensive use in medical and biological applications. Much work has been devoted to study these applications while comparatively fewer studies appear to be directed to the discharge itself. In this work, in order to better understand the kind of electrical discharge and the plasma states existing in those devices, a study of the electrical characteristics of a typical plasma jet, operated at atmospheric pressure, using either air or argon, is reported. It is found that the experimentally determined electrical characteristics are consistent with the model of a thermal arc discharge, with a highly collisional cathode sheet. The only exception is the case of argon at the smallest electrode separation studied, around 1 mm in which case the discharge is better modeled as either a non-thermal arc or a high-pressure glow. Also, variations of the electrical behavior at different gas flow rates are interpreted, consistently with the arc model, in terms of the development of fluid turbulence in the external jet.Fil: Giuliani, Leandro Estanislao. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Xaubet Brea, Magalí Noel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Grondona, Diana Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Minotti, Fernando Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Kelly, Hector Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentin

Determination of hydraulic parameters in experimental soil columns from the southeast of Buenos Aires province

La cuenca del Río Quequén Grande constituye una región representativa de los sistemas agrícolas pampeanos. El acuífero en esta región es la principal fuente de abastecimiento de agua para todos los usos, lo que pone de manifiesto la importancia de desarrollar los elementos necesarios para el estudio de la movilidad de los contaminantes a través de los suelos hacia la zona saturada. El objetivo del presente trabajo fue obtener parámetros hidráulicos bajo condiciones de saturación en columnas intactas de distintos tipos de suelos de la región, contemplando suelos de uso agrícola y natural. Se estudiaron dos series de suelo: Serie Azul y Serie Semillero Buck, con muestras tomadas en dos sectores próximos a las localidades de Lobería y La Dulce, respectivamente. Las columnas fueron eluidas con una solución acuosa de iones cloruro y se midió el incremento progresivo de conductividad. A partir de las curvas de arribo obtenidas, se ajustó la ecuación de transporte, obteniendo los valores de dispersividad y porosidad. Dichos parámetros no presentaron diferencias significativas según el uso para los suelos de Lobería, de textura franco arcillosa, indicando que la labranza no produciría modificaciones evidentes en el perfil del suelo. En La Dulce, donde los suelos poseen una textura más arenosa, los parámetros variaron según el uso del suelo, presentando una mayor dispersividad y menor porosidad del suelo bajo explotación agrícola extensiva.The Quequén Grande river basin is representative of the farming systems from the Pampas region. The aquifer is the main source of water supply for all uses, which highlights the importance to study the mobility of contaminants through the soil to the saturated zone. The aim of this study was to obtain hydraulic parameters of different soil types in the region according to land use (agricultural and natural) under saturated conditions. Two study areas were selected close to the cities La Dulce (Azul Series Soil) and Lobería (Semillero Buck Series Soil), as representatives of the dominant soil types in this area. The columns were eluted with an aqueous solution containing chloride ions and the progressive increase was measured at the end of the column. From the experimental data the breakthrough curve was adjusted using MATLAB software while dispersivity and porosity values were determined from modeled data. These parameters did not differ significantly in Lobería, so it is assumed that tillage does not produce significant changes in the soil profile. Conversely, in La Dulce land use affects the hydraulic properties of the soil leading to lower porosity and higher dispersivity values in soils under tillage use.Fil: Grondona, Sebastián I.. Universidad Nacional de Mar del PlataFil: Martínez, Daniel E.. Universidad Nacional de Mar del PlataFil: Benavente, Miguel. Universidad Nacional de Mar del PlataFil: Gonzalez, Mariana. Universidad Nacional de Mar del PlataFil: Massone, Héctor E.. Universidad Nacional de Mar del PlataFil: Miglioranza, Karina S. B.. Universidad Nacional de Mar del Plat

Enhancement of photoacoustic detection of inhomogeneities in polymers

We report a series of experiments on laser pulsed photoacoustic excitation in turbid polymer samples addressed to evaluate the sound speed in the samples and the presence of inhomogeneities in the bulk. We describe a system which allows the direct measurement of the speed of the detected waves by engraving the surface of the piece under study with a fiduciary pattern of black lines. We also describe how this pattern helps to enhance the sensitivity for the detection of an inhomogeneity in the bulk. These two facts are useful for studies in soft matter systems including, perhaps, biological samples. We have performed an experimental analysis on Grilon®samples in different situations and we show the limitations of the method.Facultad de Ingenierí

Cat-Owner Relationship and Cat Behaviour : Effects of the COVID-19 Confinement and Implications for Feline Management

The aim of this study was to explore the effects of the Italian COVID-19 lockdown on the cat-owner relationship and on cat behaviour. In order to do so, we used a questionnaire to obtain information on the owner and cat's demographics, living environment, cat behaviour, and possible changes in some aspects of the cat-owner relationship. The questionnaire was distributed online when the lockdown was still ongoing and was completed by 548 cat owners, mainly women. Our findings suggest that the greater amount of time that owners spent at home with their cats, as a consequence of the social restrictions, had a positive effect on the owner's perception of their relationship with their cat (e.g., higher frequency of interaction, greater emotional closeness, reduced perceived costs of caring for the cat). Similarly, the lockdown seemed to have improved the welfare of many cats, as suggested by the positive changes in many of their behaviours, even for those cats with pre-existing behavioural problems. Overall, our findings suggest that the lockdown provided many cats with a more thriving physical and social environment. They also highlight the need to reconsider some cat management practices commonly implemented in non-exceptional circumstances. The restrictive measures implemented to stem the spread of COVID-19 abruptly changed the lives of many cats and their owners. This study explored whether the lockdown in Italy affected the cat-owner relationship, as well as cat behaviour and welfare. A survey that included questions on owner and cat's demographics, living environment, cat behaviour and a modified version of the Cat/Dog Relationship Scale (C/DORS) was distributed online during the lockdown and was completed by 548 cat owners, mainly women (81.6%). With regard to the C/DORS subscales, both emotional closeness and cat-owner interactions increased during confinement, as opposed to a reduction in perceived costs. The effect of the type of job, family role and owner's age on the C/DORS scores suggests that the relationship improved for those owners that, due to the lockdown, increased the time spent with their cats. For 58.8% of respondents, their cat's general behaviour did not change, but when changes occurred, they were mostly positive (20.4%). Attention-seeking and demanding behaviours were the most increased during lockdown (25.7%). Cats with pre-existing problematic behaviours tended to either remain stable or improve during confinement. The overall positive effects of lockdown-related environmental changes on a cat's behaviour suggest that some aspects of commonly implemented cat management practices should be revised to improve cat welfare in normal circumstances

Determinación de parámetros hidráulicos en columnas experimentales de suelos del sudeste de la provincia de Buenos Aires

The Quequén Grande river basin is representative of the farming systems from the Pampas region. The aquifer is the main source of water supply for all uses, which highlights the importance to study the mobility of contaminants through the soil to the saturated zone. The aim of this study was to obtain hydraulic parameters of different soil types in the region according to land use (agricultural and natural) under saturated conditions. Two study areas were selected close to the cities La Dulce (Azul Series Soil) and Lobería (Semillero Buck Series Soil), as representatives of the dominant soil types in this area. The columns were eluted with an aqueous solution containing chloride ions and the progressive increase was measured at the end of the column. From the experimental data the breakthrough curve was adjusted using MATLAB software while dispersivity and porosity values were determined from modeled data. These parameters did not differ significantly in Lobería, so it is assumed that tillage does not produce significant changes in the soil profile. Conversely, in La Dulce land use affects the hydraulic properties of the soil leading to lower porosity and higher dispersivity values in soils under tillage use.La cuenca del Río Quequén Grande constituye una región representativa de los sistemas agrícolas pampeanos. El acuífero en esta región es la principal fuente de abastecimiento de agua para todos los usos, lo que pone de manifiesto la importancia de desarrollar los elementos necesarios para el estudio de la movilidad de los contaminantes a través de los suelos hacia la zona saturada. El objetivo del presente trabajo fue obtener parámetros hidráulicos bajo condiciones de saturación en columnas intactas de distintos tipos de suelos de la región, contemplando suelos de uso agrícola y natural. Se estudiaron dos series de suelo: Serie Azul y Serie Semillero Buck, con muestras tomadas en dos sectores próximos a las localidades de Lobería y La Dulce, respectivamente. Las columnas fueron eluidas con una solución acuosa de iones cloruro y se midió el incremento progresivo de conductividad. A partir de las curvas de arribo obtenidas, se ajustó la ecuación de transporte, obteniendo los valores de dispersividad y porosidad. Dichos parámetros no presentaron diferencias significativas según el uso para los suelos de Lobería, de textura franco arcillosa, indicando que la labranza no produciría modificaciones evidentes en el perfil del suelo. En La Dulce, donde los suelos poseen una textura más arenosa, los parámetros variaron según el uso del suelo, presentando una mayor dispersividad y menor porosidad del suelo bajo explotación agrícola extensiva

Enhancement of photoacoustic detection of inhomogeneities in polymers

We report a series of experiments on laser pulsed photoacoustic excitation in turbid polymer samples addressed to evaluate the sound speed in the samples and the presence of inhomogeneities in the bulk. We describe a system which allows the direct measurement of the speed of the detected waves by engraving the surface of the piece under study with a fiduciary pattern of black lines. We also describe how this pattern helps to enhance the sensitivity for the detection of an inhomogeneity in the bulk. These two facts are useful for studies in soft matter systems including, perhaps, biological samples. We have performed an experimental analysis on Grilon®samples in different situations and we show the limitations of the method.Facultad de Ingenierí