Utilización del modelo hidrológico OCINE3 en una microcuenca de pampa ondulada, Argentina

p.49-54

Crecimiento y dispersión de estructuras vegetativas de Gramón (Cynodon dactylon (L.) Pers.)

p.21-28

Evaluación del balance de energía en un cultivo de soja bajo condiciones hídricas extremas

p.1-8

Calidad de suelo : sensibilidad de variables químicas, físicas y biológicas con diferentes sistemas de manejo

p.53-60

Crecimiento, rendimiento y calidad de semillas de tres cv de Cenchrus ciliaris bajo condiciones de salinidad

La salinidad es uno de los mayores factores limitantes para la expansión de la frontera agrícola, afecta a más de 30 millones de hectáreas principalmente en las regiones áridas y semiáridas, donde es una de las principales limitaciones edáficas para la producción de plantas forrajeras. Cenchrus ciliaris (Poaceae), es una especie perenne, nativa de África y de la mitad este de Asia de conocida tolerancia a condiciones de sequía y elevadas temperaturas. Sin embargo la información sobre la tolerancia a condiciones de salinidad es escasa por lo que el objetivo general de este trabajo fue aportar conocimientos sobre los efectos de la salinidad en el rendimiento de forraje y semilla de Cenchrus ciliaris y algunos de los mecanismos fisiológicos subyacentes. Para esto se utilizaron tres cv Americana, Biloela y Texas, que se cultivaron en containers de 1000 litros sobre arena lavada durante dos temporadas. Este sistema de cultivo permitió controlar los niveles de salinidad en el sustrato, similar a una hidroponía, pero mantener a las plantas en condiciones de campo en cuanto a temperatura, radiación, humedad, vientos etc. Haciendo así que los resultados sean mucho más próximos y extrapolables a una condición real de cultivo. Los tratamientos consistieron en riegos con soluciones de NaCl de 8, 13 y 18 dS/m, sobre una base de solución nutritiva. El control consistió solamente en la mencionada solución nutritiva (3 dS/m). Para evitar la acumulación de sales en el perfil se diseñó un sistema de drenaje que permitió monitorear diariamente el lixiviado de riego y mantener el sistema estable. Los efectos de los tratamientos se evaluaron sobre variables de crecimiento y de rendimiento reproductivo. También se realizaron mediciones de potencial hídrico, osmótico, contenido relativo de agua (RWC)y acumulación de iones en lámina foliar. Para determinar si la semillas obtenidas de plantas estresadas toleran mejor condiciones de estrés durante la germinación, estas se incubaron en soluciones de NaCl de -0.5, -1, -1.5, -2, -2.5 y -3 MPa. Los resultados mostraron que los tres cv responden de manera similar frente al estrés, disminuyendo el crecimiento vegetativo y el rendimiento conforme aumenta la salinidad. Como respuesta general a los tratamientos salinos el crecimiento disminuyó al igual que lo observado para condiciones de estrés hídrico. De todas las etapas del ciclo ontogénico estudiadas la más susceptible fue la inicial que comprendió plantas que estaban iniciando la etapa reproductiva, siendo el cv Biloela el más susceptible. Luego hacia el final de la temporada de crecimiento las diferencias entre el control y el tratamiento menos salino (8 dS/m)desaparecieron. Esto indica que el cultivo es más sensible a la salinidad en la etapa vegetativa y el inicio de la etapa reproductiva. De las componentes del rendimiento reproductivo sólo el número de espigas por planta y el peso de 100 cariopses se vieron afectados. Con respecto a las variables hídricas los tres cv modificaron tanto el potencial hídrico como el osmótico y mantuvieron su RWC constante. Los iones adicionados con los tratamientos Na+ y Cl- se acumularon en hoja conforme aumentó la conductividad de las soluciones de riego. El análisis de K+ para cada cv mostró que en todos los casos los niveles de este ion fueron significativamente mayores en el control que en los tratamientos. En los tres cv estudiados se observó que semillas provenientes de plantas que crecieron en condiciones de salinidad germinaron en mayor cantidad y más rápido que las provenientes del control. En el cv Texas estas diferencias son especialmente marcadas, así semillas provenientes del tratamiento con mayor nivel de salinidad (18 S/m)germinaron casi un 50 por ciento más que las provenientes del control. El efecto de la salinidad durante el desarrollo de las semillas incrementó los niveles de germinación en los controles (0 Mpa)y en condiciones moderadas de salinidad (-0,5 a -1,5 MPa)

Atmospheric deposition of methanol over the Atlantic Ocean

In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air-sea methanol transfer along a similar to 10,000-km north-south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air-sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at similar to 5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface-an important term for improving air-sea gas exchange models.

Air/sea DMS gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

Shipboard measurements of eddy covariance dimethylsulfide (DMS) air–sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s−1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air–sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near-surface water-side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air–sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions.

Air–sea fluxes of oxygenated volatile organic compounds across the Atlantic Ocean

We present air-sea fluxes of oxygenated volatile organics compounds (OVOCs) quantified by eddy covariance (EC) during the Atlantic Meridional Transect cruise in 2012. Measurements of acetone, acetaldehyde, and methanol in air as well as in water were made in several different oceanic provinces and over a wide range of wind speeds (1-18 m s(-1)). The ocean appears to be a net sink for acetone in the higher latitudes of the North Atlantic but a source in the subtropics. In the South Atlantic, seawater acetone was near saturation relative to the atmosphere, resulting in essentially zero net flux. For acetaldehyde, the two-layer model predicts a small oceanic emission, which was not well resolved by the EC method. Chemical enhancement of air-sea acetaldehyde exchange due to aqueous hydration appears to be minor. The deposition velocity of methanol correlates linearly with the transfer velocity of sensible heat, confirming predominant airside control. We examine the relationships between the OVOC concentrations in air as well as in water, and quantify the gross emission and deposition fluxes of these gases.

Air-sea exchange of methanol and acetone during HiWinGS: Estimation of air phase, water phase gas transfer velocities

The air-sea fluxes of methanol and acetone were measured concurrently using a proton-transfer-reaction mass spectrometer (PTR-MS) with the eddy covariance (EC) technique during the High Wind Gas Exchange Study (HiWinGS) in 2013. The seawater concentrations of these compounds were also measured twice daily with the same PTR-MS coupled to a membrane inlet. Dissolved concentrations near the surface ranged from 7 to 28 nM for methanol and from 3 to 9 nM for acetone. Both gases were consistently transported from the atmosphere to the ocean as a result of their low sea surface saturations. The largest influxes were observed in regions of high atmospheric concentrations and strong winds (up to 25 m s(-1)). Comparison of the total air-sea transfer velocity of these two gases (K-a), along with the in situ sensible heat transfer rate, allows us to constrain the individual gas transfer velocity in the air phase (k(a)) and water phase (k(w)). Among existing parameterizations, the scaling of k(a) from the COARE model is the most consistent with our observations. The k(w) we estimated is comparable to the tangential (shear driven) transfer velocity previously determined from measurements of dimethyl sulfide. Lastly, we estimate the wet deposition of methanol and acetone in our study region and evaluate the lifetimes of these compounds in the surface ocean and lower atmosphere with respect to total (dry plus wet) atmospheric deposition.

Total cross sections for transfer ionization in fast ion-helium collisions

The effects of electron correlation and second-order terms on theoretical total cross sections of transfer ionization in collisions of the helium atom with fast H+, He2+ and Li3+ ions are studied and reported. The total cross sections are calculated using highly correlated wavefunctions with expansion of the transition amplitude in the Born series through the second order. The results of these calculations are in sensible agreement with experimental data.

The Fraternity of Metaphors: Jean-Luc Godard's Film Socialisme

Since the 'completion' of Histoire(s) du cinema (1988-1998), Jean-Luc Godard's work has become increasingly mosaic-like in its forms and configurations, and markedly elegiac in its ruminations on history, cinema, art, and thought. While his associative aesthetic and citational method –including his choice of ‘actors’, and the fragmentariness of his ‘soundtracks’ – can combine to create a distinctive cinematic event, the films themselves refuse to cohere around a unifying concern, or yield to a thematic schema. Not surprisingly, Film Socialisme does not offer us the illusion of narrative or structural integrity anymore than it contributes to the quotidian rhetoric of political and moral argument. It is, however, a political film in the sense that it alters something more fundamental than opinions and points of view. It transforms a way of seeing and understanding reality and history, fiction and documentary, images, and images of images. If anything, it belongs to that dissident or ‘dissensual’ category of artwork capable of ‘emancipating the spectator’ by disturbing what Jacques Rancière terms ‘the distribution of the sensible’ in that it generates gaps, openings, and spaces, poses questions, invites associations without positing a fixed position, imposing an interpretation, or allowing itself to invest in the illusion of expressive objectivity and the stability of meaning. The myriad citations and fragments that comprise the film are never intended to culminate into anything cohesive, never mind conclusive. In one sense, they have no source and no context beyond their moment in the film itself, and what we make of that moment. This article studies the degree to which Godard allows these images and sounds to combine and collide, associate and dissolve in this film, arguing that Film Socialisme is both an important intervention in the history of contemporary cinema, and necessary point of reference in any serious discussion of the relations between that cinema and political reality.

Investigation of a ship's propeller jet using momentum decay and energy decay

Previous researchers use the velocity decay as an input to investigate the ship’s propeller jet induced scour. A researcher indicated that most of the equations used to predict the stability of various protection systems are often missing a physical background. The momentum decay and energy decay are currently proposed as an initial input for seabed scouring investigation, which are more sensible in physics. Computational fluid dynamics (CFD) and laser Doppler anemometry (LDA) experiments are used to obtain the velocity data and then transforming into momentum and energy decays. The findings proposed several exponential equations of velocity, momentum and energy decays to estimate the region exposed to the seabed scouring.

Identifying childhood deprivation:How well do national indicators of poverty and social exclusion in Ireland Perform?

In the context of the significance that the life-cycle has been afforded in social policy discussion in Ireland, current national measures of poverty and social exclusion have been criticised for failing to capture such phenomena accurately in relation to particular stages of the life-course. In this paper we have taken advantage of the inclusion of a special module on childhood deprivation in EU-SILC 2009 to create reliable measures of both household basic deprivation and childhood deprivation. Overall, our analysis leads us to the conclusion that those exposed to childhood deprivation are generally a sub-set of the children captured by population indicators. Adopting a multidimensional and dynamic perspective on household resources and deprivation enables us to capture the large majority of children exposed to childhood deprivation. Restricting our attention to childhood deprivation would lead us to miss out on a significant number of children living in households experiencing basic deprivation but not exposed to childhood deprivation. It would be unwise to assume that such deprivation has no consequences for children. While there is clearly a value in supplementing existing national measures with child specific indicators, it would not appear sensible to rely solely on the latter.

A tree augmented classifier based on Extreme Imprecise Dirichlet Model

We present TANC, a TAN classifier (tree-augmented naive) based on imprecise probabilities. TANC models prior near-ignorance via the Extreme Imprecise Dirichlet Model (EDM). A first contribution of this paper is the experimental comparison between EDM and the global Imprecise Dirichlet Model using the naive credal classifier (NCC), with the aim of showing that EDM is a sensible approximation of the global IDM. TANC is able to deal with missing data in a conservative manner by considering all possible completions (without assuming them to be missing-at-random), but avoiding an exponential increase of the computational time. By experiments on real data sets, we show that TANC is more reliable than the Bayesian TAN and that it provides better performance compared to previous TANs based on imprecise probabilities. Yet, TANC is sometimes outperformed by NCC because the learned TAN structures are too complex; this calls for novel algorithms for learning the TAN structures, better suited for an imprecise probability classifier.

Contemporary Politics in the Middle East (Cambridge: Polity, 2011 – third edition)

The third edition of this dynamic book has been fully revised and updated to provide a comprehensive introduction to contemporary politics in the Middle East. Purposefully employing a clear thematic structure and including a wide range of case studies, data, visuals and further reading guidance the book explores and analyses the major issues which define the politics of this region of the globe.
Milton-Edwards begins by introducing and explaining key concepts and debates and goes on to outline the impact of colonialism and its legacy, the rise of Arab nationalism and anti-colonial politics. She then examines major political issues affecting the region, such as American foreign policy, political Islam, war and conflict, political economy, democratization, ethnicity and the role of women. The book concludes by highlighting the politics of the region in the twenty-first century and the future challenges it faces. This is a perfect introduction for undergraduates, covering key political, economic and social debates and providing updates and guidance for further reading.

"The genius of this book is that it integrates together the different themes which run through Middle Eastern politics. The coherence of the approach which the author has adopted is indicated by the manner in which she has updated the work in this second edition. Despite the substantial changes which the East has undergone since 9/11 and the 2003 Gulf War, the original line of analysis retains all its force. It remains a key reference for all those who are seeking to understand the region's politics, whether undergraduates, postgraduates or lay readers."
Tim Niblock, Exeter University
"I welcome the new edition of this comprehensive guide to the politics of such an important region of the world. It combines sensible generalizations with useful case studies of particularly important subjects. It is a must for all those who want to understand the complex politics of the modern Middle East."
Roger Owen, Harvard University
"Beverley Milton-Edwards has produced an excellent book, which is both wide-ranging in its coverage and punchy in its arguments. As such, its functions are dual. It works well as a text book, introducing the general reader to key themes in the contemporary region, from oil politics to ethnicity, to women and nationalism. But it also works as a running commentary on key debates, such as the rile of colonialism and the relationship between Islam and democracy. In short, this is a book with attitude."
Philip Robins, St Antony's College, Oxford