Influence of rainfall on the discharge, nutrient concentrations and loads of a stream of the "Pampa Ondulada" (Buenos Aires, Argentina)

The basin area of the Durazno Stream covers approx. 360 km2 of a plain with a gentle slope, mainly devoted to cattle farming and agriculture. This study examines the variability of chemical composition of surface water of the stream in relation to stream discharge, estimated from a hydrological deterministic model from rainfall data. Fifteen samplings were carried out, four in high flow condition and the rest in baseline flow. In each sampling, the main physico-chemical variables were determined. Since discharge data from this stream were not available, it was estimated in situ through an instantaneous unitary hydrograph model. Both estimations of stream discharge were similar. The main forms of dissolved inorganic nitrogen were ammonium and nitrate. The four significant components of PCA that explained 84.4 % of total variance were: mineral component, particulate matter content, ammonium and dissolved phosphorus levels, and nitrates' level. The decreased concentrations of major ions and conductivity during high flow condition suggest solutes' dilution by the massive inflow of water originated by rainfalls. The highest concentrations and loads of suspended solids (SS) (86 mg/l and 22638 kg/day) and particulate organic carbon (POC) (3.1 mg/l and 832 kg/day) were observed in the sample obtained during the rising limb of the hydrograph following a drought period, suggesting that basin erosive processes are more important during the first hours of the storm. Three of the samplings that were carried out in high flow conditions showed low mineral and nutrient content that revealed better water quality. In contrast, the sampling with the greatest total runoff (14.1 mm) showed high concentrations of ammonium (1205 μg/l) and dissolved phosphorus (561 μg/l), suggesting that a long stagnant period on soils with low permeability, could favor reduction processes of nitrate to ammonium and mobilization of dissolved phosphorus to overlying water. The nutrients' loads increased in high flow conditions most likely due to runoff from the riverbank soils. The rise of nutrients, SS, POC and total organic carbon (TOC), loads in the same or in higher proportion than the stream discharge, alerts on the risk of contamination of surface water in an agricultural basin.La cuenca del Arroyo Durazno abarca aproximadamente 360 km2 de una llanura con suave pendiente, dedicada principalmente a ganadería y agricultura. Este estudio examina la variabilidad en la composición química del agua superficial del arroyo en relación con el caudal estimado a través de un modelo hidrológico determinístico a partir de los datos de lluvia. Se realizaron quince muestreos: cuatro en condiciones de alto caudal, los restantes en caudal base. En cada muestreo se determinaron las principales variables fisico-químicas. Dado que no existen datos publicados de caudal de este arroyo, se lo estimó in situ, y a partir del modelo de hidrograma unitario. Ambas estimaciones resultaron similares. Las principales formas de nitrógeno inorgánico disuelto fueron amonio y nitrato. Los primeros 4 factores extraídos del PCA que explicaron 84.4 % de la varianza total fueron: componente mineral, contenido de material particulado, niveles de amonio y fósforo disuelto y nivel de nitratos. El decrecimiento de iones mayoritarios y conductividad durante las condiciones de alto caudal sugiere su dilución por la entrada masiva de agua por lluvias. Las mayores concentraciones y cargas de sólidos suspendidos (SS) (86 mg/l y 22638 kg/día) y carbono orgánico particulado (COP) (3.1 mg/l y 832 kg/día) se hallaron en el muestreo realizado durante la rama ascendente del hidrograma posterior a un período de sequía, sugiriendo que los procesos erosivos de la cuenca son más importantes en las primeras horas de la tormenta. Tres de los muestreos realizados en condiciones de alto caudal presentaron bajo contenido mineral y de nutrientes, indicando mejor calidad de agua. En cambio en el muestreo de mayor lámina de escorrentía acumulada (14.1 mm) las concentraciones de amonio (1205μg/l) y fósforo disuelto (561μg/l) fueron elevadas, sugiriendo que un prolongado periodo de estancamiento en un suelo de baja permeabilidad favorecería los procesos de reducción de nitratos a amonio y la movilización de fósforo disuelto al agua de inundación. Las cargas de nutrientes aumentaron en condiciones de alto caudal probablemente debido al aporte por escorrentía de suelos ribereños. El ascenso en las cargas de nutrientes, SS, COP y carbono orgánico total en igual o mayor magnitud que el caudal alerta sobre el riesgo de contaminación de las aguas superficiales en una cuenca agrícola

Interacción entre <i>Salvinia minima</i> y <i>Lemna gibba</i>: efecto sobre el crecimiento en distintos medios de cultivo

Nutrient uptake and competitive ability of the aquatic species Lemna gibba and Salvinia minima were evaluated. The experiment was carried out in a greenhouse and plants were grown as mono-plant cultures and mixed-plant cultures. Three different media were used: tap water and the chemically defined media Lemna and Hutner 1/10. Duration of the experiment was 7 days. Initial and final dry weights and DIN and SRP concentrations were determined. Relative growth rates (RGR) and nutrient uptake rates were calculated. L. gibba´s RGR values increased significantly in Hutner 1/10 medium when types of cultures were analyzed separately. RGR values decreased in Lemna and Hutner 1/10 media in mixed-plant cultures. S. minima did not show significant differences in its RGR values. In mono-plant cultures N and P uptake rates in Lemna medium were significantly larger for L. gibba. In Hutner 1/10 medium P uptake rate was greater for S. minima and N uptake rate was larger for L. gibba. The presence of S. minima negatively affected L. gibba´s growth.Instituto de Limnología "Raúl A. Ringuelet

Interacción entre <i>Salvinia minima</i> y <i>Lemna gibba</i>: efecto sobre el crecimiento en distintos medios de cultivo

Nutrient uptake and competitive ability of the aquatic species Lemna gibba and Salvinia minima were evaluated. The experiment was carried out in a greenhouse and plants were grown as mono-plant cultures and mixed-plant cultures. Three different media were used: tap water and the chemically defined media Lemna and Hutner 1/10. Duration of the experiment was 7 days. Initial and final dry weights and DIN and SRP concentrations were determined. Relative growth rates (RGR) and nutrient uptake rates were calculated. L. gibba´s RGR values increased significantly in Hutner 1/10 medium when types of cultures were analyzed separately. RGR values decreased in Lemna and Hutner 1/10 media in mixed-plant cultures. S. minima did not show significant differences in its RGR values. In mono-plant cultures N and P uptake rates in Lemna medium were significantly larger for L. gibba. In Hutner 1/10 medium P uptake rate was greater for S. minima and N uptake rate was larger for L. gibba. The presence of S. minima negatively affected L. gibba´s growth.Instituto de Limnología "Raúl A. Ringuelet

Interacción entre Salvinia minima y Lemna gibba

Nutrient uptake and competitive ability of the aquatic species Lemna gibba and Salvinia minima were evaluated. The experiment was carried out in a greenhouse and plants were grown as mono-plant cultures and mixed-plant cultures. Three different media were used: tap water and the chemically defined media Lemna and Hutner 1/10. Duration of the experiment was 7 days. Initial and final dry weights and DIN and SRP concentrations were determined. Relative growth rates (RGR) and nutrient uptake rates were calculated. L. gibba´s RGR values increased significantly in Hutner 1/10 medium when types of cultures were analyzed separately. RGR values decreased in Lemna and Hutner 1/10 media in mixed-plant cultures. S. minima did not show significant differences in its RGR values. In mono-plant cultures N and P uptake rates in Lemna medium were significantly larger for L. gibba. In Hutner 1/10 medium P uptake rate was greater for S. minima and N uptake rate was larger for L. gibba. The presence of S. minima negatively affected L. gibba´s growth.Nutrient uptake and competitive ability of the aquatic species Lemna gibba and Salvinia minima were evaluated. The experiment was carried out in a greenhouse and plants were grown as mono-plant cultures and mixed-plant cultures. Three different media were used: tap water and the chemically defined media Lemna and Hutner 1/10. Duration of the experiment was 7 days. Initial and final dry weights and DIN and SRP concentrations were determined. Relative growth rates (RGR) and nutrient uptake rates were calculated. L. gibba´s RGR values increased significantly in Hutner 1/10 medium when types of cultures were analyzed separately. RGR values decreased in Lemna and Hutner 1/10 media in mixed-plant cultures. S. minima did not show significant differences in its RGR values. In mono-plant cultures N and P uptake rates in Lemna medium were significantly larger for L. gibba. In Hutner 1/10 medium P uptake rate was greater for S. minima and N uptake rate was larger for L. gibba. The presence of S. minima negatively affected L. gibba´s growth

Modificaciones funcionales, personales y sociales de las fracturas de la extremidad proximal del fémur en pacientes mayores

Se ha realizado un estudio retrospectivo revisando las historias clínicas de 550 pacientes mayores de 69 años que sufrieron una fractura de cadera durante 1995 y 1996 en Salamanca. Cerca de la mitad de los pacientes estudiados tenían independencia casi total y el 40.22% cambió su tipo de residencia. La mayoría de los pacientes perdieron actividad y se encontraron diferencias estadísticamente significativas en la existencia o no de complicaciones. Casi todas las fracturas ocurrieron tras una caída casual por tropiezos o resbalones. El 57.67% de los pacientes tenían una intensa osteopenia. Alrededor del 25% de los pacientes realizaron rehabilitación, sobre todo los tratados con enclavados endomedulares. La mortalidad fue de 31.37% y se encontraron diferencias estadísticamente significativas al relacionarla con la actividad física previa y postratamiento y el grado de dependencia previa a la fractura. Estos cambios en la función y dependencia, tienen poca influencia en la rehabilitación y mortalidad de los pacientes.Case-history reviews and at-home interviews we used to study retrospectively the 550 patients older than 69 years who suffered a hip fracture between 1995 and 1996 in Salamanca (Spain). The average hospitalization time was 15 days. Almost half of patients were not dependent at all and 40.22% of them moved to another residence. Most patients lost activity, and it was statistically correlated to the adverse events reported. Almost every fracture occurred after a casual fall due to stumbling or sliding. 57.67 % of patients had a severe osteopenia. The most frequent fracture reported was pertrochanteric (44.67%) followed by subcapital, especially those treated with intramedullary nailing. Mortality was 31.37% and statistical differences were found between degree of activity before and after the fracture. These changes in function and type of residence have a scarce influence on rehabilitation and mortality of patients

Remark on charge conjugation in the non relativistic limit

We study the non relativistic limit of the charge conjugation operation $\cal C$ in the context of the Dirac equation coupled to an electromagnetic field. The limit is well defined and, as in the relativistic case, $\cal C$, $\cal P$ (parity) and $\cal T$ (time reversal) are the generators of a matrix group isomorphic to a semidirect sum of the dihedral group of eight elements and $\Z_2$. The existence of the limit is supported by an argument based in quantum field theory. Also, and most important, the limit exists in the context of galilean relativity. Finally, if one complexifies the Lorentz group and therefore the galilean spacetime $x_\mu$, then the explicit form of the matrix for $\cal C$ allows to interpret it, in this context, as the complex conjugation of the spatial coordinates: $\vec{x} \to \vec{x}^*$. This result is natural in a fiber bundle description.Comment: 8 page

Dark matter searches using superheated liquids

Direct detection of dark matter is one of the most important topics in modern physics. It is estimated that 22% of universe matter is composed by dark matter in front of 0.4% of ordinary matter like stars, galaxies planets and all kind of known astrophysical objects. Several kinds of experiments are nowadays involved in detection of one of the more accepted particle candidates to be dark matter: WIMPs (Weakly Interacting Massive Particles). These detectors, using several kinds of techniques: Cryogenic semiconductors, scintillation materials like I Na or noble gas chambers among others, are reporting very interesting but inconclusive results. In this paper a review of detectors that are using the superheated liquid technique in bubble chambers in order to detect WIMPs is reported. Basically, we will report about Coupp (Chicagoland observatory for underground particle physics), PICO that is composed by Coupp and Picasso researchers having the aim to build a ton experiment and also about a new detector named MOSCAB (Materia oscura a bolle) that recently published a first results of a test chamber that uses also superheated liquid technique but as a Geyser chamber.Bou Cabo, M.; Ardid Ramírez, M.; Felis-Enguix, I. (2016). Dark matter searches using superheated liquids. EPJ Web of Conferences. 121(06007):1-8. doi:10.1051/epjconf/201612106007S1812106007Rayleigh L., On the pressure developed in a liquid during the collapse of a spherical cavity (Philos. Mag34, 94, 1917)Plesset M.S., The growth of vapor bubbles in superheated liquid (J. Appl. Phys.25, 9493, 1954)Forster H.K., Growth of vapor bubbles in superheated liquid (J. Appl. Phys.05, 474, 1954)Seitz F. (Phys. Fluids1, 2, 1958)Behnke E. et al., Coupp Collaboration, First dark matter search results from a 4-kg CF3I bubble chamber operated in a deep underground site (Phys. Rev. D86, 2012)Behnke et al., Coupp Collaboration, Direct measurement of the bubble-nucleation energy threshold in a CF3I bubble chamber (Phys. Rev. D88, 2013)Archambault S., Picasso Collaboration, Dark Matter Spin-Dependent Limits for WIMPs Interactions on19F by PICASSO(Phys. Lett. B, 2009)Bertoni R. et al., A new technique for direct investigation of dark matter (Nuclear Instruments and Methods in Physics Research, A, 61–68, 2014)Bou-Cabo M. et al., LOW Radioactivity Techniques 2013 (LRT 2013): Proceedings of the IV International Workshop in Low Radioactivity Techniques, V:1549, 142 – 147Ardid M. et al., MOSCAB: Direct dark matter search using the Geyser technique, Proc. ICHEP 2014 Conf., Nucl. Phys. B: Proc. Supp. (in press