An Analytical Solution of the Advection Dispersion Equation in a Bounded Domain and Its Application to Laboratory Experiments

We study a uniform flow in a parallel plate geometry to model contaminant transport through a saturated porous medium in a semi-infinite domain in order to simulate an experimental apparatus mainly constituted by a chamber filled with a glass beads bed. The general solution of the advection dispersion equation in a porous medium was obtained by utilizing the Jacobiθ3Function. The analytical solution here presented has been provided when the inlet (Dirac) and the boundary conditions (Dirichelet, Neumann, and mixed types) are fixed. The proposed solution was used to study experimental data acquired by using a noninvasive technique

Assessment of nitrate hazards in umbria region (Italy) using field datasets: Good agriculture practices and farms sustainability

The Nitrates Directive, EU 91/676/EEC, obliged all European Union member states to introduce laws that guarantee the use of proper agriculture and farm methods, with the aim to reduce pollution resulting from the excessive use of nitrates. In this work, we estimated the potential and effective nitrogen load from agriculture, farms, civil, and industrial sources in Umbria region, Italy, and assessed the previous (and actual) contamination by nitrates at different scales. The adopted methodology uses databases of the sources, such as the type of fertilizer (inorganic or manure), the type of industrial site, the census of livestock and field data at a local, basin, and regional scale. Hydrological and geological models are used to compute infiltration. The study shows that the contribution of farms to nitrate pollution is in the order of swine > cattle > sheep and goats; while the highest agricultural load is due to arable land, followed by olive and grape. The study also shows that municipalities that have values of nitrates over the threshold for both groundwater and surface water can rapidly change their status during consecutive years. This means that rules for farm sustainability, complying with the Nitrates Directive, EU 91/676/EEC, should be defined at a sub-basin scale, where the hydrogeological conditions strongly influence infiltration

Spatiotemporal role of muscarinic signaling in early chick development: exposure to cholinomimetic agents by a mathematical model

Awareness is growing that, besides several neurotoxic effects, cholinomimetic drugs able to interfere the cholinergic neurotransmitter system may exert a teratogen effect in developing embryos of vertebrate and invertebrate organisms. Cholinomimetic substances exert their toxic activity on organisms as they inhibit the functionality of the cholinergic system by completely or partially replacing the ACh molecule both at the level of the AChE active site and at the level of acetylcholine receptors. In this work, we focused the attention on the effects of muscarinic antagonist (atropine) and agonist (carbachol) drugs during the early development and ontogenesis of chick embryos. An unsteady-state mathematical model of the drug release and fate was developed, to synchronize exposure to a gradient of drug concentrations with the different developmental events. Since concentration measures in time and space cannot be taken without damaging the embryo itself, the diffusion model was the only way to establish at each time-step the exact concentration of drug at the different points of the embryo body (considered two-dimensional up to the 50 h stage). This concentration depends on the distance and position of the embryo with respect to the releasing source. The exposure to carbachol generally enhanced dimensions and stages of the embryos, while atropine mainly caused delay in development and small size of the embryos. Both the drugs were able to cause developmental anomalies, depending on the moment of development, in a time- and dose-dependent way, regardless the expression of genes driving each event

Determining biokinetic coefficients for the upflow anaerobic sludge blanket reactor treating sugarcane wastewater in hot climate conditions

Acknowledgements The managing director of Imam Khomeini (pbuh) Agro-Industry in Shushtar and the laboratory expert of Agro-Industry Treatment Plant are highly appreciated for their cooperation in conducting this study.Peer reviewedPostprin

Non-Markoffian effects of a simple nonlinear bath

We analyze a model of a nonlinear bath consisting of a single two-level system coupled to a linear bath (a classical noise force in the limit considered here). This allows us to study the effects of a nonlinear, non-Markoffian bath in a particularly simple situation. We analyze the effects of this bath onto the dynamics of a spin by calculating the decay of the equilibrium correlator of the spin's z-component. The exact results are compared with those obtained using three commonly used approximations: a Markoffian master equation for the spin dynamics, a weak-coupling approximation, and the substitution of a linear bath for the original nonlinear bath.Comment: 7 pages, 6 figure

Spectroscopy of a Cooper-Pair box in the Autler-Townes configuration

A theoretical spectroscopic analysis of a microwave driven superconducting charge qubit (Cooper-pair box coupled) to an RLC oscillator model is performed. By treating the oscillator as a probe through the backreaction effect of the qubit on the oscillator circuit, we extract frequency splitting features analogous to the Autler-Townes effect from quantum optics, thereby extending the analogies between superconducting and quantum optical phenomenology. These features are found in a frequency band that avoids the need for high frequency measurement systems and therefore may be of use in qubit characterization and coupling schemes. In addition we find this frequency band can be adjusted to suit an experimental frequency regime by changing the oscillator frequency.Comment: 13 pages, 7 figures. v2: Revised version after referee comments. Accepted for publication by Physical Review

Synergies between SKA and ALMA: observations of Nearby Galaxies

The past decade has seen amazing advances in radioastronomy, which led to the construction of brand-new instruments such as LOFAR and ALMA, and the updating of existing ones, e. g. JVLA and e-MERLIN. The SKA will be the spearhead of a future technological development and it will change the way astrophysical topics have been studied so far by opening up new frequency windows with unprecedented spatial resolution and sensitivity. The SKA location in the southern hemisphere makes it particularly suitable to complement ALMA, which is already giving exciting results both on the local and the more distant Universe. Among the possible synergies between SKA and ALMA, we focus on the observations of nearby star forming galaxies. Star formation processes in galaxies involve all the components of the interstellar medium, so the only way to have a complete picture of them is through multifrequency observations. ALMA observes gas and dust emission, while the SKA will trace both the free-free thermal and the non-thermal synchrotron emission. The spatial comparison between these components gives information about the contribution to star formation processes provided by magnetic fields and cosmic rays. The high spatial resolution achievable with ALMA and SKA will make it possible to compare these emissions on very small spatial scales, by resolving single molecular clouds in nearby galaxies. By the time the SKA will start observing, ALMA will have already imaged many nearby galaxies in the southern hemisphere, for which no low frequency data at comparably high spatial resolution will be available. The SKA will fill this gap, and have a profound impact on the studies of nearby galaxies, making valuable contributions to our understanding of star formation processes, and of the role of magnetic fields and cosmic rays in them

Synergies between SKA and ALMA: observations of Nearby Galaxies

The past decade has seen amazing advances in radioastronomy, which led to the construction of brand-new instruments such as LOFAR and ALMA, and the updating of existing ones, e. g. JVLA and e-MERLIN. The SKA will be the spearhead of a future technological development and it will change the way astrophysical topics have been studied so far by opening up new frequency windows with unprecedented spatial resolution and sensitivity. The SKA location in the southern hemisphere makes it particularly suitable to complement ALMA, which is already giving exciting results both on the local and the more distant Universe. Among the possible synergies between SKA and ALMA, we focus on the observations of nearby star forming galaxies. Star formation processes in galaxies involve all the components of the interstellar medium, so the only way to have a complete picture of them is through multifrequency observations. ALMA observes gas and dust emission, while the SKA will trace both the free-free thermal and the non-thermal synchrotron emission. The spatial comparison between these components gives information about the contribution to star formation processes provided by magnetic fields and cosmic rays. The high spatial resolution achievable with ALMA and SKA will make it possible to compare these emissions on very small spatial scales, by resolving single molecular clouds in nearby galaxies. By the time the SKA will start observing, ALMA will have already imaged many nearby galaxies in the southern hemisphere, for which no low frequency data at comparably high spatial resolution will be available. The SKA will fill this gap, and have a profound impact on the studies of nearby galaxies, making valuable contributions to our understanding of star formation processes, and of the role of magnetic fields and cosmic rays in them

LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies

Accepted for publication in Astronomy and AstrophysicsAims. The shape of low-frequency radio continuum spectra of normal galaxies is not well understood, the key question being the role of physical processes such as thermal absorption in shaping them. In this work we take advantage of the LOFAR Multifrequency Snapshot Sky Survey (MSSS) to investigate such spectra for a large sample of nearby star-forming galaxies. Methods. Using the measured 150 MHz flux densities from the LOFAR MSSS survey and literature flux densities at various frequencies we have obtained integrated radio spectra for 106 galaxies characterised by different morphology and star formation rate. The spectra are explained through the use of a three-dimensional model of galaxy radio emission, and radiation transfer dependent on the galaxy viewing angle and absorption processes. Results. Our galaxies' spectra are generally flatter at lower compared to higher frequencies: the median spectral index α low measured between ≈ 50 MHz and 1.5 GHz is -0.57 ± 0.01 while the high-frequency one α high, calculated between 1.3 GHz and 5 GHz, is -0.77 ± 0.03. As there is no tendency for the highly inclined galaxies to have more flattened low-frequency spectra, we argue that the observed flattening is not due to thermal absorption, contradicting the suggestion of Israel & Mahoney (1990, ApJ, 352, 30). According to our modelled radio maps for M 51-like galaxies, the free-free absorption effects can be seen only below 30 MHz and in the global spectra just below 20 MHz, while in the spectra of starburst galaxies, like M 82, the flattening due to absorption is instead visible up to higher frequencies of about 150 MHz. Starbursts are however scarce in the local Universe, in accordance with the weak spectral curvature seen in the galaxies of our sample. Locally, within galactic disks, the absorption effects are distinctly visible in M 51-like galaxies as spectral flattening around 100-200 MHz in the face-on objects, and as turnovers in the edge-on ones, while in M 82-like galaxies there are strong turnovers at frequencies above 700 MHz, regardless of viewing angle. Conclusions. Our modelling of galaxy spectra suggests that the weak spectral flattening observed in the nearby galaxies studied here results principally from synchrotron spectral curvature due to cosmic ray energy losses and propagation effects. We predict much stronger effects of thermal absorption in more distant galaxies with high star formation rates. Some influence exerted by the Milky Way's foreground on the spectra of all external galaxies is also expected at very low frequencies.Peer reviewedFinal Accepted Versio

EVALUACIÓN DE LA CAPACIDAD DE INDUCCIÓN DE ANTIXENOSIS DE DOS COMPUESTOS (CINAMATO DE METILO Y ETILO) PARA CONTROLAR AL PULGÓN VERDE DE LOS CEREALES EN AVENA

La avena es el principal cereal invernal empleado como verdeo en nuestro país, cuya producción y rendimiento está afectada entre otros factores, por la presencia del pulgón verde (Schizaphis graminum). El manejo inadecuado de productos fitosanitarios ha tenido numerosas consecuencias negativas, por lo que es imperante buscar alternativas sustentables, y la integración e implementación de diferentes estrategias de control de insectos plagas tales como el uso de cultivares tolerantes y el empleo de compuestos orgánicos que apliquen los postulados de la Química Verde. Los defensas inducidas son aquellas que se generan cuando la planta detecta que está siendo atacada por patógenos y /o insectos plaga, este mecanismo esta mediado por algunas fitohormonas [1, 2], entre ellas el ácido salicílico (AS), quien tiene un rol esencial en la activación de genes de defensas que codifican para proteínas PR (proteínas asociadas a la patogénesis), y de respuesta hipersensible (RH) [3]. Se definió la antixenosis como la capacidad de las plantas de no compatibilizar con el insecto, evitando que el insecto la utilice para oviposición, alimento o refugio [4]. El Objetivo fue evaluar la capacidad de inducción de antixenosis de dos compuestos orgánicos precursores del AS (R1: cinamato de metilo y R2: cinamato de etilo), sintetizados mediantes procedimientos de bajo impacto ambiental. Se utilizaron 16 cultivares de avenas obtenidas en la CEI de Barrow y dos compuestos orgánicos R1 y R2, cuya preparación se realizó bajo procesos sustentables en la cátedra de Química Orgánica. La evaluación de antixenosis en los 16 cultivares se realizó mediante la prueba de libre selección de hospedero, en condiciones controladas de Tº, y fotoperíodo (22± 1°C; 12:12 L: O). En el estado de segunda hoja expandida (Zadok Z: 1.2) se formó un circulo con los 16 cultivares, en el centro del mismo se colocaron aproximadamente entre 7- 10 hembras ápteras adultas. A las 24 hs de la infestación se hizo el recuento del Nº áfido por cada planta. Se empleó un diseño complemente aleatorizado con 10 repeticiones (10 círculos), la ubicación de cada variedad fue sorteada al azar, hubo tres tratamientos (Testigo, R1 y R2). Se aplicó una dilución de 1x10-5 M en R1 y R2, y con Tween20 y agua en el grupo Testigo, mediante aspersión exógena hasta chorreo, 24 h antes de la infestación con los insectos, luego, se realizó el conteo del Número de insectos por planta. Los datos de los experimentos se analizaron por separado mediante análisis de varianza (ANOVA) y las medias de los distintos cultivares se compararon usando el Test de Tukey. Para un mejor ajuste a la normalidad, los datos fueron transformados con la fórmula Log (X+1). La aplicación del análisis de la varianza demostró la presencia de diferencias altamente significativas solamente para Tratamientos con los dos compuestos orgánicos (tablas 1 y 2). En el tratamiento con R1 se observó que los cultivares Nº 9 y el Nº 13 vieron mejorada significativamente su antixenosis, al condicionar un menor número de insectos por planta en relación al testigo, mientras que los restantes cultivares no modificaron tal condición (figura Nº 1). En tanto, en el tratamiento con R2, los cultivares Nº 1, 3, 4, 6, 9 y 12 mostraron un menor número de insectos por planta en relación al testigo, resultando ser más antixenoticos (figura Nº2). El único cultivar que respondió con ambos tratamientos (R1 y R2) fue el Nº 9. Se sugiere que los cambios observados en el nivel de antixenosis en los materiales estudiados podrían ser atribuidos al tratamiento con los compuestos orgánicos. Los resultados indicarían mejor efectividad en el control de los áfidos del cinamato de etilo (R2), sin embargo se sugieren más estudios para corroborar su acción repelente. La aplicación del análisis de la varianza demostró la presencia de diferencias altamente significativas solamente para Tratamientos con los dos compuestos orgánicos (tablas 1 y 2). En el tratamiento con R1 se observó que los cultivares Nº 9 y el Nº 13 vieron mejorada significativamente su antixenosis, al condicionar un menor número de insectos por planta en relación al testigo, mientras que los restantes cultivares no modificaron tal condición (figura 1). En tanto, en el tratamiento con R2, los cultivares Nº 1, 3, 4, 6, 9 y 12 mostraron un menor número de insectos por planta en relación al testigo, resultando ser más antixenoticos (figura 2). El único cultivar que respondió con ambos tratamientos (R1 y R2) fue el Nº 9. Se sugiere que los cambios observados en el nivel de antixenosis en los materiales estudiados podrían ser atribuidos al tratamiento con los compuestos orgánicos. Los resultados indicarían mejor efectividad en el control de los áfidos del cinamato de etilo (R2), sin embargo se sugieren más estudios para corroborar su acción repelente