Upper ocean vertical supply: A neglected primary factor controlling the distribution of neodymium concentrations of open ocean surface waters?

Neodymium (Nd) isotopes are an important geochemical tool to trace the present and past water mass mixing as well as continental inputs. The distribution of Nd concentrations in open ocean surface waters (0�100 m) is generally assumed to be controlled by lateral mixing of Nd from coastal surface currents and by removal through reversible particle scavenging. However, using 228Ra activity as an indicator of coastal water mass influence, surface water Nd concentration data available on key oceanic transects as a whole do not support the above scenario. From a global compilation of available data, we find that more stratified regions are generally associated with low surface Nd concentrations. This implies that upper ocean vertical supply may be an as yet neglected primary factor in determining the basin-scale variations of surface water Nd concentrations. Similar to the mechanism of nutrients supply, it is likely that stratification inhibits vertical supply of Nd from the subsurface thermocline waters and thus the magnitude of Nd flux to the surface layer. Consistently, the estimated required input flux of Nd to the surface layer to maintain the observed concentrations could be nearly two orders of magnitudes larger than riverine/dust flux, and also larger than the model-based estimation on shelf-derived coastal flux. In addition, preliminary results from modeling experiments reveal that the input from shallow boundary sources, riverine input, and release from dust are actually not the primary factors controlling Nd concentrations most notably in the Pacific and Southern Ocean surface waters.

Estimating Spatial Distribution of American Lobster Homarus Americanus Using Habitat Variables

The spatial distribution of the American lobster Homarus americanus is influenced by many factors, which are often difficult to quantify. We implemented a modeling approach for quantifying season-, size-, and sex-specific lobster spatial distribution in the Gulf of Maine with respect to environmental and spatial variables including bottom temperature, bottom salinity, latitude, longitude, depth, distance offshore, and 2 substratum features. Lobster distribution was strongly associated with temperature and depth, and differed seasonally by sex. In offshore waters in the fall, females were dominant at higher latitudes and males at lower latitudes. This segregation was not apparent in the spring although females were still dominant at higher latitudes in offshore waters. Juveniles and adults were also distributed differently; juveniles were more abundant at the lower latitudes in inshore waters, while adults were more widespread along the entire coast. These patterns are consistent with the ecology of the American lobster. This study provides a tool to evaluate changes in lobster spatial distribution with respect to changes in key habitat and other environmental variables, and consequently could be of value for the management of the American lobster.

Cross-Layer Optimizations for Multimedia Distribution over Wireless Multimedia Sensor Networks and Flying Ad-Hoc Networks with Quality of Experience Support

The proliferation of multimedia content and the demand for new audio or video services have fostered the development of a new era based on multimedia information, which allowed the evolution of Wireless Multimedia Sensor Networks (WMSNs) and also Flying Ad-Hoc Networks (FANETs). In this way, live multimedia services require real-time video transmissions with a low frame loss rate, tolerable end-to-end delay, and jitter to support video dissemination with Quality of Experience (QoE) support. Hence, a key principle in a QoE-aware approach is the transmission of high priority frames (protect them) with a minimum packet loss ratio, as well as network overhead. Moreover, multimedia content must be transmitted from a given source to the destination via intermediate nodes with high reliability in a large scale scenario. The routing service must cope with dynamic topologies caused by node failure or mobility, as well as wireless channel changes, in order to continue to operate despite dynamic topologies during multimedia transmission. Finally, understanding user satisfaction on watching a video sequence is becoming a key requirement for delivery of multimedia content with QoE support. With this goal in mind, solutions involving multimedia transmissions must take into account the video characteristics to improve video quality delivery. The main research contributions of this thesis are driven by the research question how to provide multimedia distribution with high energy-efficiency, reliability, robustness, scalability, and QoE support over wireless ad hoc networks. The thesis addresses several problem domains with contributions on different layers of the communication stack. At the application layer, we introduce a QoE-aware packet redundancy mechanism to reduce the impact of the unreliable and lossy nature of wireless environment to disseminate live multimedia content. At the network layer, we introduce two routing protocols, namely video-aware Multi-hop and multi-path hierarchical routing protocol for Efficient VIdeo transmission for static WMSN scenarios (MEVI), and cross-layer link quality and geographical-aware beaconless OR protocol for multimedia FANET scenarios (XLinGO). Both protocols enable multimedia dissemination with energy-efficiency, reliability and QoE support. This is achieved by combining multiple cross-layer metrics for routing decision in order to establish reliable routes.

Distribution of deep-sea foraminifera in surface sediments east of New Zealand

Paleobathymetric assessments of fossil foraminiferal faunas play a significant role in the analysis of the paleogeographic, sedimentary, and tectonic histories of New Zealand's Neogene marine sedimentary basins. At depths >100 m, these assessments often have large uncertainties. This study, aimed at improving the precision of paleodepth assessments, documents the present-day distribution of deep-sea foraminifera (>63 µm) in 66 samples of seafloor sediment at 90-700 m water depth (outer shelf to mid-abyssal), east of New Zealand. One hundred and thirty-nine of the 465 recorded species of benthic foraminifera are new records for the New Zealand region. Characters of the foraminiferal faunas which appear to provide the most useful information for estimating paleobathymetry are, in decreasing order of reliability: relative abundance of common benthic species; benthic species associations; upper depth limits of key benthic species; and relative abundance of planktic foraminifera. R mode cluster analysis on the quantitative census data of the 58 most abundant species of benthic foraminifera produced six species associations within three higher level clusters: (1) calcareous species most abundant at mid-bathyal to outer shelf depths (<1000 m); (2) calcareous species most abundant at mid-bathyal and greater depths (>600 m); (3) agglutinated species mostly occurring at deep abyssal depths (>3000 m). A detrended correspondence analysis ordination plot exhibits a strong relationship between these species associations and bathymetry. This is manifest in the bathymetric ranges of the relative abundance peaks of many of the common benthic species (e.g., Abditodentrix pseudothalmanni 500-2800 m, Bolivina robusta 200-650 m, Bulimina marginata f. marginata 20-600 m, B. marginata f. aculeata 400-3000 m, Cassidulina norvangi 1000-4500 m, Epistominella exigua 1000-4700 m, and Trifarina angulosa 10-650 m), which should prove useful in paleobathymetric estimates. The upper depth limits of 28 benthic foraminiferal species (e.g., Fursenkoina complanata 200 m, Bulimina truncana 450 m, Melonis affinis 550 m, Eggerella bradyi 750 m, and Cassidulina norvangi 1000 m) have potential to improve the precision of paleobathymetric estimates based initially on the total faunal composition. The planktic percentage of foraminiferal tests increases from outer shelf to upper abyssal depths followed by a rapid decline within the foraminiferal lysocline (below c. 3600 m). A planktic percentage <50% is suggestive of shelf depths, and >50% is suggestive of bathyal or abyssal depths above the CCD. In the abyssal zone there is dramatic taphonomic loss of most agglutinated tests (except some textulariids) at burial depths of 0.1-0.2 m, which negates the potential usefulness of these taxa in paleobathymetric assessments.

Spatial and seasonal distribution of Thaumarchaeota in the water column and sediment of the southern North Sea

We have examined the spatial and seasonal distribution of Thaumarchaeota in the water column and sediment of the southern North Sea using the specific intact polar lipid (IPL) hexose, phosphohexose (HPH) crenarchaeol, as well as thaumarchaeotal 16S rRNA gene abundances and expression. In the water column, a higher abundance of Thaumarchaeota was observed in the winter season than in the summer, which is in agreement with previous studies, but this was not the case in the sediment where Thaumarchaeota were most abundant in spring and summer. This observation corresponds well with the idea that ammonia availability is a key factor in thaumarchaeotal niche determination. In the surface waters of the southern North Sea, we observed a spatial variability in HPH crenarchaeol, thaumarchaeotal 16S rRNA gene abundance and transcriptional activity that corresponded well with the different water masses present. In bottom waters, a clear differentiation based on water masses was not observed; instead, we suggest that observed differences in thaumarchaeotal abundance with depth may be related to resuspension from the sediment. This could be due to suspension of benthic Thaumarchaeota to the water column or due to delivery of e.g. resuspended sediment or ammonium to the water column, which could be utilized by pelagic Thaumarchaeota. This study has shown that the seasonality of Thaumarchaeota in water and sediment is different and highlights the importance of water masses, currents and sedimentary processes in determining the spatial abundance of Thaumarchaeota in the southern North Sea.

Transport and Distribution of Hydroxyl Radicals and Oxygen Atoms from H2O Photodissociation in the Inner Coma of Comet 67P/Churyumov-Gerasimenko

With a combination of the Direct Simulation Monte Carlo (DSMC) calculation and test particle computation, the ballistic transport process of the hydroxyl radicals and oxygen atoms produced by photodissociation of water molecules in the coma of comet 67P/Churyumov-Gerasimenko is modelled. We discuss the key elements and essential features of such simulations which results can be compared with the remote-sensing and in situ measurements of cometary gas coma from the Rosetta mission at different orbital phases of this comet.

Design and Optimization of Power Delivery and Distribution Systems Using Evolutionary Computation Techniques

Nowadays computing platforms consist of a very large number of components that require to be supplied with diferent voltage levels and power requirements. Even a very small platform, like a handheld computer, may contain more than twenty diferent loads and voltage regulators. The power delivery designers of these systems are required to provide, in a very short time, the right power architecture that optimizes the performance, meets electrical specifications plus cost and size targets. The appropriate selection of the architecture and converters directly defines the performance of a given solution. Therefore, the designer needs to be able to evaluate a significant number of options in order to know with good certainty whether the selected solutions meet the size, energy eficiency and cost targets. The design dificulties of selecting the right solution arise due to the wide range of power conversion products provided by diferent manufacturers. These products range from discrete components (to build converters) to complete power conversion modules that employ diferent manufacturing technologies. Consequently, in most cases it is not possible to analyze all the alternatives (combinations of power architectures and converters) that can be built. The designer has to select a limited number of converters in order to simplify the analysis. In this thesis, in order to overcome the mentioned dificulties, a new design methodology for power supply systems is proposed. This methodology integrates evolutionary computation techniques in order to make possible analyzing a large number of possibilities. This exhaustive analysis helps the designer to quickly define a set of feasible solutions and select the best trade-off in performance according to each application. The proposed approach consists of two key steps, one for the automatic generation of architectures and other for the optimized selection of components. In this thesis are detailed the implementation of these two steps. The usefulness of the methodology is corroborated by contrasting the results using real problems and experiments designed to test the limits of the algorithms.

Response threshold models, stochastic learning automata and ant colony optimization-based decentralized self-coordination algorithms for heterogeneous multi-tasks distribution in multi-robot systems

In recent decades, there has been an increasing interest in systems comprised of several autonomous mobile robots, and as a result, there has been a substantial amount of development in the eld of Articial Intelligence, especially in Robotics. There are several studies in the literature by some researchers from the scientic community that focus on the creation of intelligent machines and devices capable to imitate the functions and movements of living beings. Multi-Robot Systems (MRS) can often deal with tasks that are dicult, if not impossible, to be accomplished by a single robot. In the context of MRS, one of the main challenges is the need to control, coordinate and synchronize the operation of multiple robots to perform a specic task. This requires the development of new strategies and methods which allow us to obtain the desired system behavior in a formal and concise way. This PhD thesis aims to study the coordination of multi-robot systems, in particular, addresses the problem of the distribution of heterogeneous multi-tasks. The main interest in these systems is to understand how from simple rules inspired by the division of labor in social insects, a group of robots can perform tasks in an organized and coordinated way. We are mainly interested on truly distributed or decentralized solutions in which the robots themselves, autonomously and in an individual manner, select a particular task so that all tasks are optimally distributed. In general, to perform the multi-tasks distribution among a team of robots, they have to synchronize their actions and exchange information. Under this approach we can speak of multi-tasks selection instead of multi-tasks assignment, which means, that the agents or robots select the tasks instead of being assigned a task by a central controller. The key element in these algorithms is the estimation ix of the stimuli and the adaptive update of the thresholds. This means that each robot performs this estimate locally depending on the load or the number of pending tasks to be performed. In addition, it is very interesting the evaluation of the results in function in each approach, comparing the results obtained by the introducing noise in the number of pending loads, with the purpose of simulate the robot's error in estimating the real number of pending tasks. The main contribution of this thesis can be found in the approach based on self-organization and division of labor in social insects. An experimental scenario for the coordination problem among multiple robots, the robustness of the approaches and the generation of dynamic tasks have been presented and discussed. The particular issues studied are: Threshold models: It presents the experiments conducted to test the response threshold model with the objective to analyze the system performance index, for the problem of the distribution of heterogeneous multitasks in multi-robot systems; also has been introduced additive noise in the number of pending loads and has been generated dynamic tasks over time. Learning automata methods: It describes the experiments to test the learning automata-based probabilistic algorithms. The approach was tested to evaluate the system performance index with additive noise and with dynamic tasks generation for the same problem of the distribution of heterogeneous multi-tasks in multi-robot systems. Ant colony optimization: The goal of the experiments presented is to test the ant colony optimization-based deterministic algorithms, to achieve the distribution of heterogeneous multi-tasks in multi-robot systems. In the experiments performed, the system performance index is evaluated by introducing additive noise and dynamic tasks generation over time.

Application of self-organizing techniques for the distribution of heterogeneous multi-tasks in multi-robot systems

This paper focuses on the general problem of coordinating of multi-robot systems, more specifically, it addresses the self-election of heterogeneous and specialized tasks by autonomous robots. In this regard, it has proposed experimenting with two different techniques based chiefly on selforganization and emergence biologically inspired, by applying response threshold models as well as ant colony optimization. Under this approach it can speak of multi-tasks selection instead of multi-tasks allocation, that means, as the agents or robots select the tasks instead of being assigned a task by a central controller. The key element in these algorithms is the estimation of the stimuli and the adaptive update of the thresholds. This means that each robot performs this estimate locally depending on the load or the number of pending tasks to be performed. It has evaluated the robustness of the algorithms, perturbing the number of pending loads to simulate the robot’s error in estimating the real number of pending tasks and also the dynamic generation of loads through time. The paper ends with a critical discussion of experimental results.

Propuesta de un marco conceptual para el análisis comparativo de las redes de distribución de dos supermercados online = Proposal of a conceptual framework for the comparative analysis of the distribution networks of two online supermarkets

In this article the network configuration for fulfillment and distribution of online orders of two British retailers is analyzed and compared. For this purpose, it is proposed a conceptual framework that consists of the key following aspects: network configuration, transportation management and location of demand. As a result is not obvious to determine the ideal centralization degree in each case. Finally, it is suggested the future development of an analytic tool that helps to choose the most appropriate model.

A partial study of vertical distribution of conventional no-till seeders and spatial variability of seed depth placement of maize in the Alentejo region, Portugal

The requirements for a good stand in a no-till field are the same as those for conventional planting as well as added field and machinery management. Among the various factors that contribute towards producing a successful maize crop, seed depth placement is a key determinant. Although most no-till planters on the market work well under good soil and residue conditions, adjustments and even modifications are frequently needed when working with compacted or wet soils or with heavy residues. The main objective of this study, carried out in 2010, 2011 and 2012, was to evaluate the vertical distribution and spatial variability of seed depth placement in a maize crop under no-till conditions, using precision farming technologies and conventional no-till seeders. The results obtained indicate that the seed depth placement was affected by soil moisture content and forward speed. The seed depth placement was negatively correlated with soil resistance and seeding depth had a significant impact on mean emergence time and the percentage of emerged plants. Shallow average depth values and high coefficients of variation suggest a need for improvements in controlling the seeders’ sowing depth mechanism or more accurate calibration by operators in the field.

Distribution of microservices for hardware interoperability in the Smart Grid

Due to the significant increase of population and their natural desire of improving their standard of living, usage of energy extracted from world commodities, especially shaped as electricity, has increased in an intense manner during the last decades. This fact brings up a challenge with a complicated solution, which is how to guarantee that there will be enough energy so as to satisfy the energy demand of the world population. Among all the possible solutions that can be adopted to mitigate this problem one of them is almost of mandatory adoption, which consists of rationalizing energy utilization, in a way that its wasteful usage is minimized and it can be leveraged during a longer period of time. One of the ways to achieve it is by means of the improvement of the power distribution grid, so that it will be able to react in a more efficient manner against common issues, such as energy demand peaks or inaccurate electricity consumption forecasts. However, in order to be able to implement this improvement it is necessary to use technologies from the ICT (Information and Communication Technologies) sphere that often present challenges in some key areas: advanced metering infrastructure integration, interoperability and interconnectivity of the devices, interfaces to offer the applications, security measures design, etc. All these challenges may imply slowing down the adoption of the smart grid as a system to prolong the lifespan and utilization of the available energy. A proposal for an intermediation architecture that will make possible solving these challenges is put forward in this Master Thesis. Besides, one implementation and the tests that have been carried out to know the performance of the presented concepts have been included as well, in a way that it can be proved that the challenges set out by the smart grid can be resolved. RESUMEN. Debido al incremento significativo de la población y su deseo natural de mejorar su nivel de vida, la utilización de la energía extraída de las materias primas mundiales, especialmente en forma de electricidad, ha aumentado de manera intensa durante las últimas décadas. Este hecho plantea un reto de solución complicada, el cual es cómo garantizar que se dispondrá de la energía suficiente como para satisfacer la demanda energética de la población mundial. De entre todas las soluciones posibles que se pueden adoptar para mitigar este problema una de ellas es de casi obligatoria adopción, la cual consiste en racionalizar la utilización de la energía, de tal forma que se minimice su malgasto y pueda aprovecharse durante más tiempo. Una de las maneras de conseguirlo es mediante la mejora de la red de distribución de electricidad para que ésta pueda reaccionar de manera más eficaz contra problemas comunes, tales como los picos de demanda de energía o previsiones imprecisas acerca del consumo de electricidad. Sin embargo, para poder implementar esta mejora es necesario utilizar tecnologías del ámbito de las TIC (Tecnologías de la Información y la Comunicación) que a menudo presentan problemas en algunas áreas clave: integración de infraestructura de medición avanzada, interoperabilidad e interconectividad de los dispositivos, interfaces que ofrecer a las aplicaciones, diseño de medidas de seguridad, etc. Todos estos retos pueden implicar una ralentización en la adopción de la red eléctrica inteligente como un sistema para alargar la vida y la utilización de la energía disponible. En este Trabajo Fin de Máster se sugiere una propuesta para una arquitectura de intermediación que posibilite la resolución de estos retos. Además, una implementación y las pruebas que se han llevado a cabo para conocer el rendimiento de los conceptos presentados también han sido incluidas, de tal forma que se demuestre que los retos que plantea la red eléctrica inteligente pueden ser solventados.

Contribute to the Study of Vertical Distribution of Conventional No-Till Seeders and Spatial Variability of Seed Depth Placement of Maize in Alentejo, Portugal

Entre os vários fatores que contribuem para a produção de uma cultura de milho, a distribuição vertical dos semeadores avaliada através da localização da semente em profundidade é um fator-chave, especialmente na técnica de sementeira direta. Simultaneamente, dada a complexidade dos ecossistemas naturais e agrícolas em sistemas de agricultura de conservação, a gestão diferenciada e localizada das parcelas assume um importante papel na análise e gestão da variabilidade das propriedades do solo e estabelecimento das culturas, nomeadamente utilizando informação geo referenciada e tecnologia expedita. Assim, o principal objetivo desta Tese foi a avaliação em culturas de milho da variabilidade espacial da localização de semente em profundidade e estabelecimento da cultura em sementeira direta usando sistemas convencionais de controlo de profundidade, tendo-se comparado com diferentes sistemas de mobilização e recorrendo a tecnologias de agricultura de precisão. Os ensaios decorreram na região Mediterrânea do Alentejo, em propriedades agrícolas no decorrer das campanhas de 2010, 2011, 2012 e 2015 em 6 diferentes campos experimentais. O trabalho experimental consistiu em ensaios com avaliações in loco do solo e cultura, consumo de combustível das operações e deteção remota. Os resultados obtidos indicam que não só o sistema de mobilização afetou a localização da semente em profundidade, como em sementeira direta a profundidade de sementeira foi afetada pelo teor de humidade do solo, resistência do solo à profundidade e velocidade da operação de sementeira. Adicionalmente observaram-se condições heterogéneas de emergência e estabelecimento da cultura afetadas por condições físicas de compactação do solo. Comparando os diferentes sistemas de mobilização, obteve-se uma significativa redução de combustível para a técnica de sementeira direta, apesar de se terem observado diferenças estatísticas significativas considerando diferentes calibrações de profundidade de sementeira Do trabalho realizado nesta Tese ressalva-se a importância que as tecnologias de agricultura de precisão podem ter no acompanhamento e avaliação de culturas em sementeira direta, bem como a necessidade de melhores procedimentos no controlo de profundidade dos semeadores pelo respetivos operadores ou ao invés, a adoção de semeadores com mecanismos ativos de controlo de profundidade. ABSTRACT Among the various factors that contribute towards producing a successful maize crop, seeders vertical distribution evaluated through seed depth placement is a key determinant, especially under a no-tillage technique. At the same time in conservation agriculture systems due to the complexity of natural and agricultural ecosystems site specific management became an important approach to understand and manage the variability of soil properties and crop establishment, especially when using geo spatial information and affording readily technology Thus, the main objective of this Thesis was to evaluate the spatial variability of seed depth placement and crop establishment in maize crops under no-tillage conditions compared to different tillage systems, using conventional seed depth control no till seeders and precision farming technologies. Trials were carried out in the Mediterranean region of Alentejo, in private farms along the sowing operations season over the years 2010, 2011, 2012 and 2015 in 6 different experimental fields. Experimental work covered field tests with in loco soil and crop evaluations, fuel operation evaluations and aerial sensing. The results obtained indicate that not only tillage system affected seed depth placement but under no till conditions seed depth was affected by soil moisture content, soil resistance to penetration and seeders forward speed. In addition uneven crop seedling and establishment depended on seed depth placement and could be affected by physical problems of compaction layers. Significant reduction in fuel consumption was observed for no till operations although significant differences observed according to different setting calibrations of seed depth control. According to the results, precision agriculture is an important tool to evaluate crops under no till conditions and seed depth mechanisms should be more accurate by the operators or is determinant the adoption of new active depth control technology to improve seeders performance.

Modeling soil processes : Review, key challenges, and new perspectives

Peer reviewed

Systemic hypoxia changes the organ-specific distribution of vascular endothelial growth factor and its receptors

Vascular endothelial growth factor (VEGF) plays a key role in physiological blood vessel formation and pathological angiogenesis such as tumor growth and ischemic diseases. Hypoxia is a potent inducer of VEGF in vitro. Here we demonstrate that VEGF is induced in vivo by exposing mice to systemic hypoxia. VEGF induction was highest in brain, but also occurred in kidney, testis, lung, heart, and liver. In situ hybridization analysis revealed that a distinct subset of cells within a given organ, such as glial cells and neurons in brain, tubular cells in kidney, and Sertoli cells in testis, responded to the hypoxic stimulus with an increase in VEGF expression. Surprisingly, however, other cells at sites of constitutive VEGF expression in normal adult tissues, such as epithelial cells in the choroid plexus and kidney glomeruli, decreased VEGF expression in response to the hypoxic stimulus. Furthermore, in addition to VEGF itself, expression of VEGF receptor-1 (VEGFR-1), but not VEGFR-2, was induced by hypoxia in endothelial cells of lung, heart, brain, kidney, and liver. VEGF itself was never found to be up-regulated in endothelial cells under hypoxic conditions, consistent with its paracrine action during normoxia. Our results show that the response to hypoxia in vivo is differentially regulated at the level of specific cell types or layers in certain organs. In these tissues, up- or down-regulation of VEGF and VEGFR-1 during hypoxia may influence their oxygenation after angiogenesis or modulate vascular permeability.