(Table 5) Quaternary paleoproductivity of organic carbon in oceans based on DSDP cores

By analogy with the present-day ocean, primary productivity of paleoceans can be reconstructed using calculations based on content of organic carbon in sediments and their accumulation rates. Results of calculations based on published data show that primary productivity of organic carbon, mass of phosphorus involved in the process, and content of phosphorus in ocean waters were relatively stable during Cenozoic and Late Mesozoic. Prior to precipitation on the seafloor together with biogenic detritus, dissolved phosphorus could repeatedly be involved in the biogeochemical cycle. Therefore, only less than 0.1% of phosphorus is retained in bottom sediments. Bulk phosphorus accumulation rate in ocean sediments is partly consistent with calculated primary productivity. Some epochs of phosphate accumulation also coincide with maxima of primary productivity and minima of the fossilization coefficient of organic carbon. The latter fact can testify to episodes of acceleration of organic matter mineralization and release of phosphorus from sediments leading to increase in the phosphorus reserve in paleoceans and phosphate accumulation in some places.

Age determination of Southeast Atlantic sediment cores

Angola Basin and Cape Basin (southeast Atlantic) surface sediments and sediment cores show that maxima in the abundance of taraxerol (relative to other land-derived lipids) covary with maxima in the relative abundance of pollen from the mangrove tree genus Rhizophora and that in the surface sediments offshore maxima in the relative abundance of taraxerol occur at latitudes with abundant coastal mangrove forests. Together with the observation that Rhizophora mangle and Rhizophora racemosa leaves are extraordinarily rich in taraxerol, this strongly indicates that taraxerol can be used as a lipid biomarker for mangrove input to the SE Atlantic. The proxy-environment relations for taraxerol and Rhizophora pollen down-core show that increased taraxerol and Rhizophora pollen abundances occur during transgressions and periods with a humid climate. These environmental changes modify the coastal erosion and sedimentation patterns, enhancing the extent of the mangrove ecosystem and/or the transport of mangrove organic matter offshore. Analyses of mid-Pleistocene sediments show that interruption of the pattern of taraxerol maxima during precession minima occurs almost only during periods of low obliquity. This demonstrates the complex environmental response of the interaction between precession-related humidity cycles and obliquity-related sea-level changes on mangrove input.

Stable isotope ratios of foraminifera from various DSDP/ODP sites

The equator to high southern latitude sea surface and vertical temperature gradients are reconstructed from oxygen isotope values of planktonic and benthic foraminifers for the following five time intervals: late Paleocene, early Eocene, early middle Eocene, late Eocene, and early Oligocene. Paleotemperatures are calculated using standard oxygen isotope/temperature equations with adjustments to account for (1) variations in sea water delta18O related to changes in global ice volume over time and (2) latitudinal gradients in surface water delta18O. These reconstructions indicate that sea-surface temperatures (SST) of the Southern Oceans in the early Eocene were as high as 15°C, whereas temperatures during the late Paleocene and early middle Eocene reached maximum levels of 10°-12°C. By the late Eocene and early Oligocene high latitude SST had declined to 6 and 4°C, respectively. For most of the early Paleogene, low latitude sub-tropical temperatures remained constant and well within the range of Holocene temperatures (24°-25°C) but by the late Eocene and early Oligocene declined to values in the range of 18° to 22°C. The late Paleogene apparent decline in tropical temperatures, however, might be artificial because of dissolution of near-surface foraminifera tests which biased sediment assemblages toward deeper-dwelling foraminifera. Moreover, according to recent plate reconstructions, it appears that the majority of sites upon which the late Eocene and early Oligocene tropical temperatures were previously established were located either in or near regions likely to have been influenced by upwelling. Global deepwater temperature on average paralleled southern ocean SST for most of the Paleogene. We speculate based on the overall timing and character of marine sea surface temperature variation during the Paleogene that some combination of both higher levels of greenhouse gases and increased heat transport was responsible for the exceptional high-latitude warmth of the early Eocene.

Mid-Pleistocene Mg/Ca, temperature and stable isotopes from Globigerinoides ruber white and Globorotalia inflata of sediment core GeoB3801-6 from the subtropical South Atlantic

The glacial marine isotope stage 14 (MIS 14) appears in many climate records as an unusually warm glacial. During this period an almost monospecific, up to 1.5 m thick, laminated layer of the giant diatom Ethmodiscus rex has been deposited below the South Atlantic Subtropical Gyre. This oligotrophic region is today less favorable for diatom growth with sediments typically consisting of calcareous nannofossil oozes. We have reconstructed temperatures and the stable oxygen isotopic compositions of sea surface and thermocline water (d18Ow) from planktonic foraminiferal (Globigerinoides ruber and Globorotalia inflata) Mg/Ca and stable oxygen isotopes to test whether perturbations in surface ocean conditions contributed to the deposition of the diatom layer at ~530 kyr B.P. Temperatures and d18Ow values reconstructed from this diatom ooze interval are highly variable, with maxima similar to interglacial values. Since the area of the Ethmodiscus oozes resembles the region where Agulhas rings are present, we interpret these hydrographic changes to reflect the varying influence of warm and saline water of Indian Ocean origin that entered the Subtropical Gyre trapped in Agulhas rings. The formation of the Ethmodiscus oozes is associated with a period of maximum Agulhas leakage and a maximum frequency of Agulhas ring formation caused by a termination-type position of the Subtropical Front during the unusual warm MIS 14. The input of silica through the Agulhas rings enabled the shift in primary production from calcareous nannoplankton to diatoms, leading to the deposition of the massive diatom oozes.

Age determination of sediment cores from the Panama Basin

High-resolution percent Corg and delta18Oforam records obtained from Panama Basin core Atlantis II 54-25PC and additional data from nearby core P7 show that enhanced burial of organic carbon has characterized every major glacial period for the last 500 kyr in that area. Both Corg concentration and mass accumulation rate profiles exhibit a sawtooth pattern with maxima occurring typically in the later stages of glacial periods. Comparison with dust records suggests that the carbon accumulation rate profile reflects both the upwelling history and a variable rate of iron input during the late Quaternary. The sawtooth character may derive from increased wind velocities and rates of upwelling during glacials which are indirectly related to ice volume (Sarnthein et al., 1988). The rapid decline in export production at the end of glacials in the equatorial Pacific may be attributed to the retreat of ice sheets (thus reduced wind velocities and upwelling) coupled with a coincident decline in atmospheric dust load and/or delivery rate. The Corg accumulation rate profiles do not correlate well with atmospheric CO2 records. For example, atmospheric CO2 was already at a minimum 40 kyr ago when production in the Panama Basin began increasing dramatically, commensurate with an increase in global dust levels. Using the relationship between the degree of photosynthetic fractionation and the concentration of free CO2 in the surface ocean postulated by Popp et al. (1989), delta13Corg measurements made on core P7 show that Panama Basin surface waters have been supplying CO2 to the atmosphere continually for at least the last 50 kyr. There is no evidence for a flux of CO2 into the surface ocean in this area at any time during this period despite the higher production. If the Panama Basin cores are representative of the eastern and central equatorial Pacific, then these observations weaken the influence on CO2 drawdown postulated for increased glacial productivity at low latitudes.

Effect of Aspect Ratio on the Three-Dimensional Global Instability Analysis of Incompressible Open Cavity Flows

The stability analysis of open cavity flows is a problem of great interest in the aeronautical industry. This type of flow can appear, for example, in landing gears or auxiliary power unit configurations. Open cavity flows is very sensitive to any change in the configuration, either physical (incoming boundary layer, Reynolds or Mach numbers) or geometrical (length to depth and length to width ratio). In this work, we have focused on the effect of geometry and of the Reynolds number on the stability properties of a threedimensional spanwise periodic cavity flow in the incompressible limit. To that end, BiGlobal analysis is used to investigate the instabilities in this configuration. The basic flow is obtained by the numerical integration of the Navier-Stokes equations with laminar boundary layers imposed upstream. The 3D perturbation, assumed to be periodic in the spanwise direction, is obtained as the solution of the global eigenvalue problem. A parametric study has been performed, analyzing the stability of the flow under variation of the Reynolds number, the L/D ratio of the cavity, and the spanwise wavenumber β. For consistency, multidomain high order numerical schemes have been used in all the computations, either basic flow or eigenvalue problems. The results allow to define the neutral curves in the range of L/D = 1 to L/D = 3. A scaling relating the frequency of the eigenmodes and the length to depth ratio is provided, based on the analysis results.

Validation of microsatellite markers for cytotype discrimination in the model grass Brachypodium distachyon

Brachypodium distachyon (2n = 2x = 10) is a small annual grass species where the existence of three different cytotypes (10, 20 and 30 chromosomes) has long been regarded as a case of autopolyploid series, with x = 5. However, it has been demonstrated that the cytotypes assumed to be polyploids represent two separate Brachypodium species recently named as B. stacei (2n = 2x = 20) and B. hybridum (2n = 4x = 30). The aim of this study was to find a PCR-based alternative approach that could replace standard cytotyping methods (i. e., chromosome counting and flow cytometry) to characterize each of the three Brachypodium species. We have analyzed with four microsatellite (SSR) markers eighty-three Brachypodium distachyon-type lines from varied locations in Spain, including the Balearic and Canary Islands. Within this set of lines, 64, 4 and 15 had 10, 20 and 30 chromosomes, respectively. The surveyed markers produced cytotype-specific SSR profiles. So, a single amplification product was generated in the diploid samples, with non-overlapping allelic ranges between the 2n = 10 and 2n = 20 cytotypes, whereas two bands, one in the size range of each of the diploid cytotypes, were amplified in the 2n = 30 lines. Furthermore, the remarkable size difference obtained with the SSR ALB165 allowed the identification of the Brachypodium species by simple agarose gel electrophoresis.

Thermal food processing optimization: Algorithms and software

The algorithms and graphic user interface software package ?OPT-PROx? are developed to meet food engineering needs related to canned food thermal processing simulation and optimization. The adaptive random search algorithm and its modification coupled with penalty function?s approach, and the finite difference methods with cubic spline approximation are utilized by ?OPT-PROx? package (http://tomakechoice. com/optprox/index.html). The diversity of thermal food processing optimization problems with different objectives and required constraints are solvable by developed software. The geometries supported by the ?OPT-PROx? are the following: (1) cylinder, (2) rectangle, (3) sphere. The mean square error minimization principle is utilized in order to estimate the heat transfer coefficient of food to be heated under optimal condition. The developed user friendly dialogue and used numerical procedures makes the ?OPT-PROx? software useful to food scientists in research and education, as well as to engineers involved in optimization of thermal food processing.

La evolución del paisaje fluvial en la confluencia de los ríos Tajo y Jarama

La tesis doctoral que se presenta realiza un análisis de la evolución del paisaje fluvial de las riberas de los ríos Tajo y Jarama en el entorno de Aranjuez desde una perspectiva múltiple. Contempla y conjuga aspectos naturales, tales como los hidrológicos, geomorfológicos y ecológicos; también culturales, como la regulación hidrológica y la gestión del agua, las intervenciones en cauce y márgenes, la evolución de la propiedad y los cambios de usos del suelo, fundamentalmente. Este análisis ha permitido identificar el sistema de factores, dinámico y complejo, que ha creado este paisaje, así como las interrelaciones, conexiones, condicionantes y dependencias de los descriptores paisajísticos considerados. Por ejemplo, se han estudiado las relaciones cruzadas observadas entre dinámica fluvial-propiedad de la tierra-estado de conservación, cuestiones que hasta la fecha no habían sido tratadas, evaluadas o cuantificadas en otros trabajos dedicados a esta zona. La investigación se ha organizado en tres fases fundamentales que han dado lugar a los capítulos centrales del documento (capítulos 2, 3 y 4). En primer lugar, se ha realizado una caracterización de los factores, naturales y culturales, que organizan el paisaje de este territorio eminentemente fluvial (geomorfología, factores climáticos e hidrológicos, vegetación, propiedad de la tierra y elementos culturales de significación paisajística). A continuación, se ha realizado el estudio de la evolución del paisaje fluvial mediante el análisis de diversos elementos, previamente identificados y caracterizados. Para ello se han procesado imágenes aéreas correspondientes a cinco series temporales así como varios planos antiguos, obteniendo una amplia base de datos que se ha analizado estadísticamente. Finalmente, se han contrastado los resultados parciales obtenidos en los capítulos anteriores, lo que ha permitido identificar relaciones causales entre los factores que organizan el paisaje y la evolución de los elementos que lo constituyen. También, interconexiones entre factores o entre elementos. Este método de trabajo ha resultado muy útil para la comprensión del funcionamiento y evolución de un sistema complejo, como el paisaje de la vega de Aranjuez, un territorio con profundas y antiguas intervenciones culturales donde lo natural, en cualquier caso, siempre subyace. Es posible que la principal aportación de este trabajo, también su diferencia más destacada respecto a otros estudios de paisaje, haya sido mostrar una visión completa y exhaustiva de todos los factores que han intervenido en la conformación y evolución del paisaje fluvial, destacando las relaciones que se establecen entre ellos. Esta manera de proceder puede tener una interesante faceta aplicada, de tal manera que resulta un instrumento muy útil para el diseño de planes de gestión de este territorio fluvial. No en vano, una parte sustancial de la vega del Tajo-Jarama en Aranjuez es un Lugar de Importancia Comunitaria (LIC) y su posterior e ineludible declaración como Zona de Especial Conservación (ZEC) de la Red Natura 2000, de acuerdo con lo establecido en la Directiva 92/43/CE, exige la elaboración de un Plan de Gestión que, en gran medida, podría nutrirse de lo presentado, analizado e interpretado en este trabajo. En este sentido, conviene señalar la conciencia ya asumida de considerar, por su carácter integrador de la realidad territorial, el paisaje como elemento clave para la gestión adecuada de la naturaleza y el territorio. Por otra parte, se considera que los resultados de esta Tesis Doctoral permitirían plantear medidas para la puesta en valor de un paisaje sobresaliente, cuyos límites sobrepasan con creces los que en la actualidad conforman el Paisaje Cultural declarado por la UNESCO. En suma, el análisis de este espacio fluvial realizado con la profundidad y amplitud que permite el método de trabajo seguido puede utilizarse para el diseño de estrategias que dirijan la evolución de este territorio en una línea que garantice su conservación global en términos paisajísticos, patrimoniales y ecológicos, permitiendo además, de este modo, su uso equilibrado como recurso económico, cultural o educativo. This doctoral thesis shows an analysis of fluvial landscape evolution from multiple perspectives on the banks of Tagus and Jarama rivers, around Aranjuez. The thesis contemplates and combines natural features, such as hydrological, geomorphological and ecological features, as well as cultural features, like hydrological regulation and water management, interventions in channels and margins, changes in ownership and land use changes, mainly. This analysis has allowed to identify the factors system, dynamic and complex, that this landscape has created, as well as the interrelationships, connections, constraints and dependencies among considered landscape descriptors. For example, we have studied the relationships observed among fluvial dynamics- land ownership -conservation status, issues not addressed, assessed or quantified up to now in other works about this area. The research is organized into three major phases that led to the paper's central chapters (Chapters 2, 3 and 4). First, there has been a characterization of the factors, both natural and cultural, that organize the landscape of this predominantly fluvial area (geomorphology, climate and hydrological factors, vegetation, land and cultural elements of landscape significance). Then, it was made to study of fluvial landscape evolution by analyzing various elements previously identified and characterized. Aerial images were processed for five series and several old maps, obtaining an extensive database, that has been analyzed statistically. Finally, we have contrasted the partial results obtained in the previous chapters, making it possible to identify causal relationships between the factors that organize the landscape and the evolution of the elements that constitute it. This working method has been very useful for understanding the operation and evolution of a complex system, as the landscape of the Vega de Aranjuez, a territory with deep and ancient cultural interventions where anyway, nature feature always lies. It is possible that the main contribution of this work, also its most prominent difference compared with other studies of landscape, has been to show a complete and exhaustive view of all factors involved in the formation and evolution of the fluvial landscape, highlighting the relationships established among them. This approach could have an interesting applied facet, so that is a very useful tool for designing management plans on this river territory. Not surprisingly, a substantial part of the valley of the Tagus-Jarama in Aranjuez is a Site of Community Importance (SCI) and their subsequent and inevitable declaration as Special Area of Conservation (SAC) of the Natura 2000 network, in accordance with the provisions Directive 92/43/EC, requires the development of a management plan that largely could draw on what was presented, analyzed and interpreted in this paper. In this regard, it should be noted conscience and assumed to consider, on the inclusiveness of territorial reality, the landscape as a key element for the proper management of nature and territory. On the other hand, it is considered that the results of this thesis allow to propose measures for enhancement of outstanding scenery, which go well beyond the boundaries that currently the Cultural Landscape declared by UNESCO. In sum, the analysis of this river area made with the depth and breadth that enables working method can be used to design strategies that address the evolution of this territory in a line that guarantees global conservation landscape terms, heritage and ecological, also, allowing its use as a balancing economic, cultural or educational resource.

Electron current to a probe in a magnetized, collisional plasma

Collisional analysis of electron collection by a probe in a strongly magnetized, fully ionized plasma is carried out. A solution to the complete set of macroscopic equations with classical transport coefficients that is wholly consistent in the domain is determined; R and le are probe radius and electron gyroradius, respectively. If R2/le 2 is large compared with mi/3me probe large compared with ion gyroradius, ion–electron energy exchange—rather than electron heat diffusion—keeps electrons isothermal. For smaller probes at negative bias, however, electron cooling occurs in the plasma beyond the sheath, with a potential overshoot lying well away from it. The probe characteristic in the electron-retarding range may then mimic the characteristic for a two electron-temperature plasma and lead to an overestimate of electron temperature; the validity of these results for other transport models is discussed

Nonparametric generalized belief propagation based on pseudo-junction tree for cooperative localization in wireless networks

Non-parametric belief propagation (NBP) is a well-known message passing method for cooperative localization in wireless networks. However, due to the over-counting problem in the networks with loops, NBP’s convergence is not guaranteed, and its estimates are typically less accurate. One solution for this problem is non-parametric generalized belief propagation based on junction tree. However, this method is intractable in large-scale networks due to the high-complexity of the junction tree formation, and the high-dimensionality of the particles. Therefore, in this article, we propose the non-parametric generalized belief propagation based on pseudo-junction tree (NGBP-PJT). The main difference comparing with the standard method is the formation of pseudo-junction tree, which represents the approximated junction tree based on thin graph. In addition, in order to decrease the number of high-dimensional particles, we use more informative importance density function, and reduce the dimensionality of the messages. As by-product, we also propose NBP based on thin graph (NBP-TG), a cheaper variant of NBP, which runs on the same graph as NGBP-PJT. According to our simulation and experimental results, NGBP-PJT method outperforms NBP and NBP-TG in terms of accuracy, computational, and communication cost in reasonably sized networks.

Competitive exclusion in a two-especies chemotasis model

We consider a mathematical model for the spatio-temporal evolution of two biological species in a competitive situation. Besides diffusing, both species move toward higher concentrations of a chemical substance which is produced by themselves. The resulting system consists of two parabolic equations with Lotka–Volterra-type kinetic terms and chemotactic cross-diffusion, along with an elliptic equation describing the behavior of the chemical. We study the question in how far the phenomenon of competitive exclusion occurs in such a context. We identify parameter regimes for which indeed one of the species dies out asymptotically, whereas the other reaches its carrying capacity in the large time limit.

Variable-density jet flows induced by concentrated sources of momentum and energy

The planar and axisymmetric variable-density flows induced in a quiescent gas by a concentrated source of momentum that is simultaneously either a source or a sink of energy are investigated for application to the description of the velocity and temperature far fields in laminar gaseous jets with either large or small values of the initial jet-to-ambient temperature ratio. The source fluxes of momentum and heat are used to construct the characteristic scales of velocity and length in the region where the density differences are of the order of the ambient density, which is slender for the large values of the Reynolds number considered herein. The problem reduces to the integration of the dimensionless boundary-layer conservation equations, giving a solution that depends on the gas transport properties but is otherwise free of parameters. The boundary conditions at the jet exit for integration are obtained by analysing the self-similar flow that appears near the heat source in planar and axisymmetric configurations and also near the heat sink in the planar case. Numerical integrations of the boundary-layer equations with these conditions give solutions that describe accurately the velocity and temperature fields of very hot planar and round jets and also of very cold plane jets in the far field region where the density and temperature differences are comparable to the ambient values. Simple scaling arguments indicate that the point source description does not apply, however, to cold round jets, whose far field region is not large compared with the jet development region, as verified by numerical integrations

Efecto de la fertilización orgánica y mineral en las propiedades del suelo, la emisión de los principales gases de efecto invernadero y en las diferentes fases fenológicas del cultivo de café (Coffea arabica L.)

El cultivo de café es de gran importancia a nivel mundial (ICO, 2011), y en el Ecuador ha sido uno de los cultivos más importantes en la generación de divisas (COFENAC, 2011). Sin embargo en los sistemas productivos de este país se puede apreciar el uso inapropiado de fertilizantes, lo que conlleva a una pérdida de nutrientes, por lo que es importante estudiar las dosis adecuadas para la fertilización tanto mineral como orgánica. El objetivo del trabajo fue evaluar el efecto de la fertilización mineral y orgánica en diferentes dosis en un monocultivo de café en la provincia de Loja, sobre las propiedades del suelo, la emisión de los principales gases que provocan el efecto invernadero y la fenología y productividad del cultivo. En la provincia de Loja (Ecuador) se seleccionó un área de 2.520 m2 en la que se establecieron 21 parcelas de café arábigo (Coffea arabica L.) var. caturra y se aplicó tres tratamientos con tres repeticiones de fertilización mineral y tres orgánicos con dosis: bajas minerales (MIN 1= 157 Kg NPK ha-1 año-1 para el primer año y 425 Kg NPK ha-1 año-1 para el segundo año), medias minerales (MIN 2= 325 Kg NPK ha-1 año-1 para el primer año y 650 Kg NPK ha-1 año-1 en el segundo año) y altas minerales (MIN 3= 487 y 875 Kg NPK ha-1 año-1 para el primer y segundo año respectivamente), bajas orgánicas (ORG 1= 147 Kg NPK ha-1 año-1 en el primer año y 388 Kg NPK ha-1 año-1 en el año dos), medias orgánicas (ORG 2= 265 Kg NPK ha-1 año-1 para el primer año y 541 Kg NPK ha-1 año-1 en el segundo año), altas orgánicas (ORG 3= 368 Kg NPK ha-1 año-1 para el primer año y 727 Kg NPK ha-1 año-1 en el segundo año) y fertilización cero (TES = sin fertilización). Se usó urea, roca fosfórica y muriato de potasio en la fertilización mineral y humus (Bioabor) en la orgánica, más un tratamiento testigo, cada tratamiento tuvo tres repeticiones. El tiempo de evaluación de los fertilizantes aplicados fue de dos años consecutivos, la fertilización se la realizó dos veces por año y en base a análisis del suelo y demandas nutricionales del cultivo. para determinar las características del suelo se realizó muestreos de suelos en cada parcela a una profundidad de 20 cm de estas muestras los parámetro iniciales determinados fueron: color (Munsell), textura (método del hidrómetro), pH (relación 1:2,5 suelo-agua), Materia orgánica (Walkey y Black), Nitrógeno (Micro Kjendahl), Fósforo (Bray y Kurtz), Potasio (Olsen), estos procesos se repitieron cada seis meses para poder evaluar los cambios de que se producen debido a la fertilización mineral y orgánica en el cultivo. Las emisiones de gases efecto invernadero desde el suelo al ambiente se determinaron por el método de cámara cerrada (Rondón, 2000) y la concentración por cromatografía de gases. Las mediciones fisiológicas (altura de planta, ancho de copa, grosor de tallo y producción) se las evaluó cada dos meses, a excepción de la producción que fue anual al término de cada cosecha. Además se realizó el análisis económico de la productividad del cultivo. El análisis estadístico de datos se lo realizó con el programa SPSS v. 17.0. Las medias fueron comprobadas mediante ANOVAS de un factor con test de Tukey (P < 0,05). El beneficio económico se estimó en términos de ingresos y gastos totales que se presentaron en el ensayo. Los resultados obtenidos al término del ensayo indican que los tratamientos MIN 2 y MIN 3 produjeron cambios más significativos en comparación con los otros tratamientos establecidos en la mejora de fertilidad del suelo, el pH ha sido menos afectado en la acidificación en comparación con los tratamientos orgánicos que se han acidificado mayormente; la materia orgánica (MO) tuvo incrementos considerablemente bueno en estos dos tratamientos, sin embargo fueron superados por los tratamientos de fertilización orgánica; el nitrógeno total (Nt )y el potasio (K) también presentaron mejores valores al termino del ensayo y el fósforo (P) mostro incrementos buenos aunque un poco menores que los de los tratamientos ORG 2 y ORG 3. En lo que respecta a las emisiones de gases efecto invernadero, los flujos acumulados de óxido nitroso (N2O) en los dos años han aumentado en todos los tratamientos en comparación con el tratamiento Testigo, pero de manera considerable y con mayores flujos en el tratamiento MIN 3 y MIN 2 que se podrían considerarse los de mayor contaminación por N2O al ambiente lo que se le atribuye a las dosis de fertilización mineral aplicadas en el periodo de investigación, los tratamiento MIN 1 y todos los tratamientos orgánicos muestran menores emisiones al ambiente. Las emisiones de metano (CH4) no muestran mayores diferencias de emisiones entre tratamientos, siendo los mayores emisores los tratamientos ORG 3 y ORG 2 posiblemente debido al abono orgánico y añadido al suelo; para las emisiones de dióxido de carbono (CO2) de manera similar al CH4 el tratamiento ORG 3 fue el que presento mayores emisiones, los flujos de CO2 al ambiente de los otros tratamientos fueron menores y no presentaron diferencias significativas entre ellos. La variables fisiológicas en todos los casos apoyaron al desarrollo de las plantas de café, esto al ser comparadas con el tratamiento Testigo, sin embargo las que alcanzaron las mayores altitudes, anchos de copas y diámetro de tallo fueron las plantas del tratamiento MIN 3, seguido del MIN 3, no mostrando significancia entre ellos, y para los tratamientos orgánicos el que presento muy buenos resultados en estas variables ha sido el ORG 3, el cual no presento diferencias significativas con el MIN 2, lo cual comprueba que la fertilización mineral es más efectiva en este caso frente a la orgánica. Para el primer año de producción el tratamiento mineral con fertilización MIN 3 es el que obtuvo mayor producción no presentando diferencia estadística con el tratamiento con el MIN 2, no obstante fueron significativamente mayores que los otros tratamientos. Vale indicar que también el tratamiento MIN 1 y el tratamiento ORG 3 han presentado una producción considerable de café no mostrando diferencias estadísticas entre ellos. Para el segundo año la producción el cultivo mostró mayores rendimientos que el primer año de evaluación en todos los tratamientos, esto debido a la fisiología propia del cultivo y por otra parte se atribuye a la adición de fertilizantes que se ha realizado durante todo el ensayo; de manera similar al anterior los tratamientos MIN 3 y MIN 2 obtuvieron mejores rendimientos, no enseñando diferencias estadísticas significativas entre ellos, no obstante el tratamiento mineral dosis MEDIA no presentó significancia estadística con el ORG 3. El benéfico económico ha resultado mayor en el tratamiento MIN 3 y MIN 2, aunque el tratamiento MIN 2, es el que obtiene la mejor relación costo-beneficio; los tratamientos ORG 2 y ORG 3 y Testigo has producido beneficios negativos para el productor. En cuanto a la parte ambiental se considera que los mejores tratamientos en cuanto ha cuidado ambiental serían los tratamientos MIN 1 y ORG 1, sin embargo a nivel de producción y rentabilidad para el productor baja. ABSTRACT Coffee growing has great importance worldwide (ICO, 2011), and in Ecuador, it has been one of the most important crops to generate income (COFENAC, 2011). However, in the productive systems of this country, the inappropriate use of fertilizers has been observed which produces loss of nutrients, thus it is important to study suitable doses for mineral and organic fertilizing. The purpose of the study was to evaluate the effect of mineral and organic fertilizing at different doses in a coffee monoculture in the province of Loja on soil characteristics, emission of the main gasses that produce the greenhouse effect and the phenology and productivity of crops. In the province of Loja (Ecuador) an area of 2.520 m2 was chosen, where 21 plots of Arabica coffee (Coffea arabica L.), the caturra variety were cultivated and three treatments with three repetitions each one for mineral and organic fertilization were used with doses that ranged from: mineral low (MIN 1= 157 Kg NPK ha-1 año-1 for the first year y 425 Kg NPK ha-1 año-1 for the second year), mineral medium (MIN 2= 325 Kg NPK ha-1 año-1 for the first year y 650 Kg NPK ha-1 año-1 I the second year) y mineral high (MIN 3= 487 y 875 Kg NPK ha-1 año-1 for the first and second year respectively), organic low (ORG 1= 147 Kg NPK ha-1 año-1 in the first year y 388 Kg NPK ha-1 año-1 in the second year), organics medium (ORG 2= 265 Kg NPK ha-1 año-1 for the first year y 541 Kg NPK ha-1 año-1 in the second year), organics high (ORG 3= 368 Kg NPK ha-1 año-1 for the first year and 727 Kg NPK ha-1 año-1 in the second year) y fertilization zero (TES = no fertilization).; urea, phosphoric rock and muriate of potash were used in the mineral fertilization and humus (Bioabor) in the organic, plus a blank treatment. Time to evaluate the applied fertilizers was for two consecutive years, fertilization was done twice per year based on soil analysis and nutritional requirements of the crops. In order to determine the characteristics of the soil, samples of soil in each plot with a depth of 20 cm were done; from these samples, the determined initial parameters were: color (Munsell), texture (hydrometer method), pH (soil-water 1:2,5 relation), organic matter (Walkey y Black), nitrogen (Micro Kjendahl), phosphorus (Bray y Kurtz), potassium (Olsen); these processes were repeated each six months in order to evaluate the changes that are produced due to mineral and organic fertilization in the crops. The emissions of greenhouse gasses from the soil to the atmosphere were determined by using enclosure method (Rondón, 2000) and the concentration, by using gas chromatography during the whole testing. The physiological measures (plant height, width of the top of the tree, thickness of the stem and production) were evaluated each two months, except for production which was annual at the end of each harvest. Moreover, the economic analysis of the productivity of the crops was done. The statistical analysis of the data was done using SPSS v. 17.0. The means were proved by ANOVAS with a factor of a Tukey test (P < 0,05). The economic benefit was estimated in terms of incomes and total expenses which were presented in the essay. The results obtained at the end of the essay show that the MIN 2 and MIN 3 treatments produced more meaningful changes in comparison with the other treatments used to improve soil fertility; pH was less affected in the acidification compared with the organic treatments which were greatly acidified; organic matter (MO) had increased considerably in these two treatments; however, they were surpassed by the organic treatments of fertilization; total nitrogen (Nt) and potassium (K) also presented better results at the end of the essay and phosphorus (P) showed good increasing figures although a little lower compared with ORG 2 and ORG 3 treatments. Regarding the emission of the greenhouse gasses, the fluxes accumulated from nitrous oxide (N2O) in two years increased in all the treatments in comparison with the blank treatment, but in a greater form and with higher fluxes in the MIN 3 and MIN 2 treatments which can be considered as the ones with greater contamination of N2O in the atmosphere, this can be due to the applied mineral doses to fertilize during the process; MIN 1 treatments and all the organic ones showed lower emission to the atmosphere. Methane emissions (CH4) did not show major differences in emissions in the treatments, being the greater emissions the ORG 3 and ORG 2 treatments; this is possibly due to the organic compost added to the soil; regarding carbon dioxide (CO2) emissions, in a similar way to CH4, the ORG 3 treatment was the one that presented greater emissions, the CO2 emissions to the atmosphere in the other treatments were lower and did not present meaningful differences among them. The physiological variables in all the cases helped coffee crops grow, this was observed when compared with the blank treatment; however, plants that reached the greatest height, width of top and diameter of stem were the plants of the MIN 3 treatment, followed by MIN 3, which did not show much significance among them, and for the organic treatments, the one that presented great results in these variables was ORG 3, which did not show meaningful differences compared with MIN 2, which proves that mineral fertilization is more effective in this case compared with the organic. In the first year of production, the mineral treatment with MIN 3 fertilization obtained greater production and thus did not show statistical difference with MIN 2 treatment, although the other treatments were greater. It is worth mentioning that MIN 1 treatment and ORG 3 treatment presented a meaningful production of coffee, not showing statistical differences among them. For the second year, the production of the crops showed greater profits than in the first year of evaluation in all the treatments, this was due to the physiological properties of the crops and on the other hand, it might be due to the addition of fertilizers during the whole essay; in a similar way, MIN 3 and MIN 2 performed better, not showing greater statistical differences among them, although the mineral treatment MEDIUM doses did not show statistical difference compared with ORG 3. The economic benefit was greater in the MIN 3 and MIN 2 treatments, although MIN 2 treatment is the one that shows the best cost-benefit ratios; ORG 2 and ORG 3 treatments and the blank produced negative benefits for the producer. Regarding the environment, the best treatments to care for the atmosphere are considered to be MIN 1 and ORG 1 treatments; however, regarding production volume and profitability they were low for the producer.

Design of a Semi-analytical Method to Describe Plasma-Wall Interactions

Electric probes are objects immersed in the plasma with sharp boundaries which collect of emit charged particles. Consequently, the nearby plasma evolves under abrupt imposed and/or naturally emerging conditions. There could be localized currents, different time scales for plasma species evolution, charge separation and absorbing-emitting walls. The traditional numerical schemes based on differences often transform these disparate boundary conditions into computational singularities. This is the case of models using advection-diffusion differential equations with source-sink terms (also called Fokker-Planck equations). These equations are used in both, fluid and kinetic descriptions, to obtain the distribution functions or the density for each plasma species close to the boundaries. We present a resolution method grounded on an integral advancing scheme by using approximate Green's functions, also called short-time propagators. All the integrals, as a path integration process, are numerically calculated, what states a robust grid-free computational integral method, which is unconditionally stable for any time step. Hence, the sharp boundary conditions, as the current emission from a wall, can be treated during the short-time regime providing solutions that works as if they were known for each time step analytically. The form of the propagator (typically a multivariate Gaussian) is not unique and it can be adjusted during the advancing scheme to preserve the conserved quantities of the problem. The effects of the electric or magnetic fields can be incorporated into the iterative algorithm. The method allows smooth transitions of the evolving solutions even when abrupt discontinuities are present. In this work it is proposed a procedure to incorporate, for the very first time, the boundary conditions in the numerical integral scheme. This numerical scheme is applied to model the plasma bulk interaction with a charge-emitting electrode, dealing with fluid diffusion equations combined with Poisson equation self-consistently. It has been checked the stability of this computational method under any number of iterations, even for advancing in time electrons and ions having different time scales. This work establishes the basis to deal in future work with problems related to plasma thrusters or emissive probes in electromagnetic fields.