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Hemophilia A is an X-linked hereditary disorder that results from deficient coagulation factor VIII (FVIII) activity, leading to spontaneous bleeding episodes, particularly in joints and muscles. FVIII deficiency has been associated with altered bone remodeling, dysregulated macrophage polarization, and inflammatory processes that are associated with the neoformation of abnormal blood vessels. Treatment based on FVIII replacement can lead to the development of inhibitors that render FVIII concentrate infusion ineffective. In this context, hemophilia has entered a new therapeutic era with the development of new drugs, such as emicizumab, that seek to restore the hemostatic balance by bypassing pathologically acquired antibodies. We discuss the potential extrahemostatic functions of FVIII that may be crucial for defining future therapies in hemophilia.

Resumen Las distonias son trastornos del movimiento caracterizados por contracciones musculares sostenidas que producen movimientos repetitivos de torsion o posturas anormales. Pueden clasificarse segun la etiologia como primarias (formas idiopaticas y geneticas) o secundarias. La presentacion asociada con episodios generalizados, intensos y con exacerbacion de contracturas musculares intensas que suelen ser refractarias a la farmacoterapia tradicional se conoce como status distonico o tormenta distonica. Se presenta el caso de un paciente de 33 anos, con antecedente de sordera congenita, trastorno por consumo de sustancias psicoactivas y tratamiento psicofarmacologico con antipsicoticos, que presento un cuadro distonico grave que evoluciono a un status distonico.

Dystonia is a movement disorder characterised by sustained muscle contractions that produce repetitive twisting movements or abnormal postures. It can be classified according to the aetiology as primary (idiopathic and genetic forms), or secondary. The presentation associated with generalised, intense episodes and with exacerbation of severe muscle contractures and usually refractory to traditional pharmacotherapy is known as dystonic status or dystonic storm. In the present article, a case is presented of a 33-year-old patient with a history of congenital deafness, stimulant use disorder and on psychopharmacological treatment with antipsychotics, who presented with a severe dystonic reaction that evolved to a status dystonicus.

The exploration of unknown environments is a challenge in robotics. The proposed method approaches this problem by combining the Fast Marching Square path planning technique with the machine learning method called Gaussian processes (GP). The Fast Marching Square method is used to determine the most unexplored areas of the environment and to plan the path of the vehicle from the current position to the selected point. The GP model is used to obtain predictions about the unexplored regions of the environment based on the collected data so far during the exploration. The use of Unmanned Aerial Vehicles (UAVs) for exploration and surveillance has increased exponentially in the recent years, due to their sensor equipment capabilities and their versatility for flying over difficult terrain. By defining the weight each method has on the selection of the next point to explore, we can focus the UAV on the points with more interesting data defined by the user (i.e. bodies of water), the most unexplored regions, or a combination of both. We present an study on the influence of these weights on the mean absolute error (MAE) and predictive variance obtained from the GP model and test the algorithm on a real environment obtained from a satellite image. We show that we are able to generate an accurate depiction of the environment way faster than traditional methods such as the Boustrophedon. This research was funded by the EUROPEAN COMMISSION: Innovation and Networks Executive Agency (INEA), through the European H2020 LABYRINTH project. Grant agreement H2020-MG-2019-TwoStages-861696.

The Red Española de Mastocitosis (Spanish Network on Mastocytosis) score (REMAs) and the National Institutes of Health idiopathic clonal anaphylaxis score (NICAS) were developed for more efficient screening of mast cell (MC) clonality in MC activation syndromes. In a limited idiopathic anaphylaxis case series, the NICAS showed higher accuracy vs. the REMAs.To compare the performance of the REMAs vs. the NICAS in the diagnosis of MC clonality.Diagnostic value of the REMAs vs. the NICAS was compared in 182 patients (63% men; median age: 56y) presenting with anaphylaxis triggered by Hymenoptera venom allergy (45%), drugs (15%), food (11%), idiopathic anaphylaxis (20%), and mixed causes (10%). KIT mutation was assessed in parallel in whole blood and bone marrow (BM) and when negative, in highly-purified BM MC. TPSAB1 was genotyped in a subset of 71 patients.Higher accuracy and rates of correctly classified patients were found for the REMAs (82% and 84%) vs. the NICAS (75% and 75%; p=0.02 and p=0.03, respectively), particularly among men (p=0.05), SM cases (p=0.05), patients presenting anaphylaxis due to any cause featuring urticaria (p=0.04), cardiovascular symptoms (p=0.02) and/or presyncope (p=0.02) and among those with a bloodThe combined use of the REMAs and blood detection of KIT

This work analyses the features and performance of supercritical CO2 cycles with multi-heating (heat supplies at different temperature) in Concentrating Solar Power plants, including its internal coherent integration. The specific features of multi-heating cycles fit perfectly with the characteristics of concentrating solar energy. The integration requires the design of a new type of solar field to accommodate the solar radiation hitting the receiver to the multi-heating requirements. This new solar field has a similar configuration to the solar tower, but receiver and heliostats are divided into two sections, and each section meets different requirements in concentration ratio, fluid temperature, and absorbed heat flux. This new solar field, called multi-heating solar tower, achieves higher efficiencies than standard solar towers with softer thermal requirements. The flexibility of the multi-heating structure is very useful to solve efficiently the restrictions of supercritical CO2 cycles caused by the variations of specific heat close to the critical point. The resulting CSP plant with multi-heating achieves higher efficiency than plants with standard solar towers and supercritical CO2 cycle.

The performance of anomaly-based intrusion detection systems depends on the quality of the datasets used to form normal activity profiles. Suitable datasets should include high volumes of real-life data free from attack instances. On account of this requirement, obtaining quality datasets from collected data requires a process of data sanitization that may be prohibitive if done manually, or uncertain if fully automated. In this work, we propose a sanitization approach for obtaining datasets from HTTP traces suited for training, testing, or validating anomaly-based attack detectors. Our methodology has two sequential phases. In the first phase, we clean known attacks from data using a pattern-based approach that relies on tools that detect URI-based known attacks. In the second phase, we complement the result of the first phase by conducting assisted manual labeling systematically and efficiently, setting the focus of expert examination not on the raw data (which would be millions of URIs), but on the set of words that compose the URIs. This dramatically downsizes the volume of data that requires expert discernment, making manual sanitization of large datasets feasible. We have applied our method to sanitize a trace that includes 45 million requests received by the library web server of the University of Seville. We were able to generate clean datasets in less than 84 h with only 33 h of manual supervision. We have also applied our method to some public benchmark datasets, confirming that attacks unnoticed by signature-based detectors can be discovered in a reduced time span.

This study analyzes international branch campus (IBC) literature trends from 1960 to 2017 through a systematic review of the different research approaches, views, and positions to map the global scientific production. Over the last two decades, universities worldwide have opened branch campuses abroad, reaching a peak of 249 across thirty-three countries in January 2017. In fact, international studies and surveys have identified a 26% increase over the last five years as well as a concentration of the industry. Since 2017, the emergent field of IBC has experienced a geometric growth regarding the number of academic publications on this topic. The results of the review indicate an important amount of literature on IBC related to some of the topics studied—managerial and academic staff issues and educational hubs—and a lack of research on a wide range of areas.

A new thermodynamic coefficient, called logarithmic factor of isobaric expansion, is defined for a better guidance in the cycle characterization of regenerative cycles working totally or partially at supercritical conditions. The logarithmic factor of isobaric expansion allows to generalize the characterization of cycles working around the critical point, agglutinating supercritical and transcritical cycles under a unique type of cycle: the pericritical cycle. The analysis of pericritical cycles allows to analyze all the cycles working around the critical point together, without the limitation that may involve the study of supercritical and transcritical cycles separately. Enthalpy and entropy balances give the internal relations among the cycle relevant variables in a thermodynamic mapping. The new thermodynamic coefficients defined in the paper identify the regions where the compression work is lower. But the lower compression work is counteracted by some limitations in the heat transfer regenerative phase, where the hot fluid of the low-pressure side heats the (same) fluid at the high-pressure side. The logarithmic factor of isobaric expansion in the compressor indicates the relevance of the compression work and the heat regeneration in the cycle, which will affect the thermal efficiency. Pericritical cycles with lower compression work and so higher limitations in the regenerative phase, handle better the inefficiencies of the cycle components at the expense of larger pressure ratios. Moreover, cycles with lower compressor inlet temperatures and higher high-side pressures take more advantage of the benefits of reducing compression work, which involves higher thermal efficiencies at the expense of larger pressure ratios.

In recent years, the large volumes of stream data and the near real-time requirements of data streaming applications have exacerbated the need for new scalable algorithms and programming interfaces for distributed and shared-memory platforms. To contribute in this direction, this paper presents a new distributed MPI back end for GrPPI, a C++ high-level generic interface of data-intensive and stream processing parallel patterns. This back end, as a new execution policy, supports distributed and hybrid (distributed+shared-memory) parallel executions of the Pipeline and Farm patterns, where the hybrid mode combines the MPI policy with a GrPPI shared-memory one. These patterns internally leverage distributed queues, which can be configured to use two-sided or one-sided MPI primitives to communicate items among nodes. A detailed analysis of the GrPPI MPI execution policy reports considerable benefits from the programmability, flexibility and readability points of view. The experimental evaluation of two different streaming applications with different distributed and shared-memory scenarios reports considerable performance gains with respect to the sequential versions at the expense of negligible GrPPI overheads. This work was partially supported by the EU project No. 801091 "ASPIDE: Exascale programming models for extreme data process ing"; and the project TIN2013-41350-P "Scalable Data Management Techniques for High-End Computing Systems" from the Ministerio de Economía y Competitividad , Spain.

Highlights • 3D cell cultures present similar drugs resistance features than in vivo tumours. • Unlike 2D cell cultures, 3D culture approaches mimic better the tumour microenvironment. • Collagen scaffolds result in a better osteosarcoma 3D proliferation than soft hydrogels. • Osteosarcoma 3D models constitute an appealing approach for bone mineralisation studies. • Combination of microfluidic/bioprinting technology with bone 3D cultures as ideal tools to study bone sarcomas., Bone sarcomas are rare tumour entities that arise from the mesenchyme most of which are highly heterogeneous at the cellular, genetic and epigenetic levels. The three main types are osteosarcoma, Ewing sarcoma, and chondrosarcoma. These oncological entities are characterised by high morbidity and mortality and an absence of significant therapeutic improvement in the last four decades. In the field of oncology, in vitro cultures of cancer cells have been extensively used for drug screening unfortunately with limited success. Indeed, despite the massive knowledge acquired from conventional 2D culture methods, scientific community has been challenged by the loss of efficacy of drugs when moved to clinical trials. The recent explosion of new 3D culture methods is paving the way to more relevant in vitro models mimicking the in vivo tumour environment (e.g. bone structure) with biological responses close to the in vivo context. The present review gives a brief overview of the latest advances of the 3D culture methods used for studying primary bone sarcomas.

The work presented in this paper is focused on the single-tube configuration for linear Fresnel receiver. Specifically, this article analyses the feasibility of a new configuration: a hybrid loop in which the first modules, at lower working temperature, use non-evacuated receivers with medium thermal performance, and the remaining, at greater temperature, use evacuated receivers with high thermal performance. The non-evacuated receiver considered in this work consists of a pyromark tube inside a cavity provided with a secondary reflector opened to the ambient. The second one is based on an evacuated tube, similar to those of parabolic trough, and it is also inside an opened cavity with a secondary reflector. In the first place, this work performs a comparative analysis of the heat loss associated to the three single-tube receiver designs proposed: evacuated, non-evacuated and non-evacuated with a glass plate at the aperture. The heat loss is quantified in each case as a function of three parameters: the temperature difference between the tube wall and the environment, the incident concentrated flux on the tube and the wind velocity. Although the evacuated design has the lowest heat loss, the differences with the other two designs decrease as the working temperature is lower. Thus, a hybrid loop is proposed, which consists of non-evacuated modules at the beginning and evacuated modules at the end. The lower investment of the non-evacuated tubes, as well as their robustness and simplicity, can compensate for the lower energy absorbed by these type of receivers. Next, a study of the annual electricity cost produced by Fresnel plants with hybrid loop is performed. The work concludes that there are specific configurations of hybrid loops that minimize the electricity cost, when the different investment, operation and maintenance costs of the receivers are quantified. The maximum percentage of non-evacuated tubes in the loop will depend on the technology and the working temperature range.

This study is focused on comparing four supercritical fluids: Ethane, Xenon, Methane and Nitrogen, as possible alternative to supercritical Carbon Dioxide (s-CO2) in Brayton power cycles coupled to line- focusing solar power plants with Solar Salt (60% NaNO3; 40% KNO3) as heat transfer fluid. The Simple Brayton cycle with heat recuperation and reheating is the configuration selected in this paper, providing a balance of plant design with reduced number of equipment and cost. The gross plant efficiency is calculated fixing the recuperator conductance (UA) for different Turbine Inlet Temperatures (TIT), confirming the maximum plant gross efficiency is related with the minimum allowable recuperator pinch point temperature. The reheating pressure and compressor inlet temperature are optimized with the mathematical algorithms SUBPLEX, UOBYQA and NEWOUA. According to the REFPROP database ranges of applicability, the maximum TIT limits are established for the supercritical fluids (N2 TIT = 550 °C, CO2 TIT = 550 °C, C2H6 TIT = 400 °C, Xe TIT = 450 °C and CH4 TIT = 350 °C). The reference scenario considered for calculating the thermosolar plant energy balances and simulations is the wet-cooling system with a Compressor Inlet Temperature (CIT = 32 °C). The gross efficiency results with the wet-cooling system are: N2 (45.8%), CO2 (44.37%), C2H6 (40.74%), Xe (39.88%), CH4 (32.15%). The plant efficiency is also translated into solar field effective aperture area and estimated cost, for a fixed power output. For optimizing the solar collector aperture area and cost, the Primary Heat Exchanger (PHX) and the ReHeating Heat Exchanger (RHX) capacity ratio (CR) are fixed (CR = 1). The dry-cooling system scenario (CIT = 47 °C) is alto estimated: N2 (43.34%), CO2 (42.42%), C2H6 (37.34%), Xe (37.26%), CH4 (29.53%). For predicting the recuperator heat exchanger dimensions for a fixed conductance (UA), the heat transfer coefficient (HTC) is calculated with the Dittus–Boelter correlation and compared with the CO2 as reference. The C2H6, and CH4 have relative higher HTC in relation with CO2. Also is calculated the recuperator pressure drop. The C2H6, CH4 and N2 pressure drop is lower in comparison with the CO2 for the same operating conditions. The energy efficiency in solar power station coupled to Brayton cycle is very constrained by the ambient temperature variation, impacting directly in the dry-cooling system performance. For this reason a Compressor Inlet Temperature (CIT) sensing analysis is carried out ranging from 32 °C to 57 °C, and also varying TIT from 400 °C to 550 °C. A sensing analysis is also developed varying the Turbine Inlet Pressure (TIP) from 200 bar to 375 bar. The CO2 improves the plant efficiency when increasing the TIP from 250 bar to 350 bar, however the rest of fluids (Ethane, Methane, Nitrogen and Xenon) nearly not suffered any impact in the plant efficiency when increasing the TIP.

Purpose To evaluate the development of an extracorporeal membrane oxygenation (ECMO) program for the treatment of acute respiratory distress syndrome (ARDS) in adults. Methods a) Descriptive study of 15 cases treated since the program approval from 2010 to 2016. b) Case–control study matching the 15 ECMO cases with the 52 severe ARDS treated between 2005 and 2011 in which alternative rescue treatments (prone ventilation, tracheal gas insufflation (TGI) and/or the administration of inhaled nitric oxide (iNO)) were used. Results ECMO experience : Mortality 47% (7/15). Four patients died due to complications directly related to ECMO therapy. ICU stay 46.6 ± 45 days (range 4–138). Hospital stay 72.4 ± 98 days (range 4–320). Case–control : The mortality in the control group was 77% (44/52). The ECMO group practically doubled the mean days of ICU and hospital stay ( p Economic analysis : The hospital cost per patient in the ECMO group doubled compared to that of the control group (USD 77,099 vs USD 37,660). However, the cost per survivor was reduced by 4% (USD 144,560 vs USD 150,640, respectively). Conclusions Our results endorse the use of ECMO as a rescue therapy in adults with ARDS, although there are some risks associated with a learning curve as well as an important increase in the days of patient stay. The justification for the maintenance of an ECMO program in adults should be based on future studies of efficacy and cost effectiveness.

Solar Thermal Electric (STE) plants can integrate Thermal Energy Storage (TES) in order to generate electricity when the energy source (Sun radiation) has vanished. TES technology has become a very important asset for this type of renewable energy source, but it has induced a rise in electricity cost in many cases. One of the reasons is the need of larger solar fields as the TES capacity increases because the solar field has to provide thermal power both to generate electricity and to charge the storage. The economic effects of improving the plant performance seem to have some internal complexities that must be investigated covering the internal relations among the main parts of a STE plant: the solar field, the power block and the energy storage. This paper presents an analytical study of these relations aimed at deriving a better understanding of the cost/performance behavior of STE plants. As the power block is a mature and commercial technology with well-established efficiencies and specific costs (in $/W, for instance), it has been taken as the reference element in modelling the plant. The other parts of the plant, i.e., the solar field and the energy storage, have been characterized in cost and energy management by a set of high-level parameters. Of course, a coarse definition cannot give very accurate results for a specific design, but it can be the guideline for the selection and sizing of a plant. It is worth noting that each type of solar thermal power plant has a different parametric scenario, corresponding to its essential design window. In this paper, comparisons among plants with different parametric scenarios are restricted to one-axis concentration solar fields, where the coarse model is easily characterized. The results show that the optimum plant configuration, in terms of TES capacity and solar field size, depends on the solar field and TES costs relative to power block cost. Moreover, it is shown that some parametric scenarios always lead to an increase in the cost of electricity when the energy storage capacity is enlarged. On the contrary, parametric scenarios associated to cheaper solar fields yield a much better economic result when TES is embodied in the plant. Additionally, TES efficiency is also identified as a parameter with high impact in the performance of the whole system. This result seems obvious, but the model gives numerical values that can help to optimize the selection process in a project. For instance, it is assessed that the lower the TES efficiency, the greater the relevance of reducing solar field costs is in order to obtain low electricity generation costs. As a general conclusion, the model points out that Fresnel-type solar fields are much better suited than parabolic trough collectors for integrating thermal energy storage. This implies that Fresnel plants present a higher potential to cover the peaks of electricity demand, which results into bigger profits.

Multi-heating cycles reduce regenerator irreversibility, resulting in an increase of exergy efficiency. While a single heat source supplies the thermal power in simple regenerative cycles, in multi-heating cycles additional heat sources at lower temperatures supply part of this power along the regeneration. The greater the number of these additional heats, the higher the exergy efficiency is. An exergy analysis compares multi-heating and simple regenerative cycles working in the surroundings of the critical point. The main purpose is to identify the thermodynamic region in which there is a greater benefit of multi-heating, trying to abstract from the fluid as much as possible. The effect of compressor inlet temperature and limiting pressures is studied by means of parametric analysis. Cycles with the compressor working at pressures above the discontinuity line (set of coexistence line and Widom line) have small precooler irreversibilities and large regenerator irreversibilities. Multi-heating cycles take advantage of these conditions since they can reduce the regenerator irreversibilities and maintain the precooler irreversibilities small, leading to high exergy efficiencies. The results show that the exergy efficiency of multi-heating cycles may be up to 24% greater than in simple cycles.

For ectotherms, thermal physiology plays a fundamental role in the establishment and success of invasive species in novel areas and, ultimately, in their ecological interactions with native species. Invasive species are assumed to have a greater ability to exploit the thermal environment, higher acclimation capacities, a wider thermal tolerance range, and better relative performance under a range of thermal conditions. Here we compare the thermal ecophysiology of two species that occur in sympatry in a tropical dry forest of the Pacific coast of Mexico, the microendemic species Benedetti's Leaf-toed Gecko (Phyllodactylus benedettii) and the invasive Common House Gecko (Hemidactylus frenatus). We characterized their patterns of thermoregulation, thermoregulatory efficiency, thermal tolerances, and thermal sensitivity of locomotor performance. In addition, we included morphological variables and an index of body condition to evaluate their effects on the thermal sensitivity of locomotor performance in these species. Although the two species had similar selected temperatures and thermal tolerances, they contrasted in their thermoregulatory strategies and thermal sensitivity of locomotor performance. Hemidactylus frenatus had a higher performance than the native species, P. benedettii, which would represent an ecological advantage for the former species. Nevertheless, we suggest that given the spatial and temporal limitations in habitat use of the two species, the probability of agonistic interactions between them is reduced. We recommend exploring additional biotic attributes, such as competition, behavior and niche overlap in order assess the role of alternative factors favoring the success of invasive species.

In this work, it is studied several dryout parameters (the dryout onset, first and total dryout, its associated azimuthal position and local steam qualities) in a triple helical coil once-through steam generator under quasi-steady working conditions (inlet pressure, P IN ∈ [37.9, 39.2] bar, inlet subcooling, Δ T sub ≈ 0 ° C and total mass flow rate, m ws ≈ 0.082 kg · s-1) which exchanges heat with a molten salts counterflow under quasi-steady pressure and temperature conditions (atmospheric pressure and inlet temperature, T IN ∈ [472, 477] ° C) but transient mass flow rate, m ms , depending on the helical coil diameter, D. For this purpose, a CFD model (Computational Fluid Dynamics model) has been used which has been evaluated with the experimental data obtained during a discharge test of the 300 kWth thermal storage prototype with integrated steam generator of the Casaccia Research Center (ENEA, Italy), previous benchmarking of two phase flow model. Results show, within the working conditions range and considering the particular steam generator characteristics, the two-phase flow behavior is uniform. This information has not been reported yet on available literature. In addition, numerical local steam qualities are compared with those calculated by using forced convective boiling correlations suitable for this type of steam generator geometry, concluding that: 270 ° Ruffel’s and Santini’s correlations are the most appropriate during first dryout, and to assume a local steam quality value of 0.97 during total dryout the most suitable approximation. This work can be useful for those who pretend to scale-up such a steam generator for industrial applications requiring process heat and/or power generation.

La hiperplasia idiopatica difusa de celulas endocrinas es considerada una lesion premaligna por la Organizacion Mundial de la Salud desde 1999. Ya han sido publicados numerosos casos a lo largo de los anos sobre este tema, describiendo sus caracteristicas. El primer caso, una mujer de mediana edad, diagnosticada de asma, con un patron nodular bilateral en las pruebas de imagen y de curso clinico favorable, es buen ejemplo-resumen de la forma mas frecuente de presentacion. El segundo caso describe por primera vez un posible acumulo familiar con dos pacientes en la misma familia. Confiando en aumentar la casuistica sobre esta patologia, y en anadir alguna novedad, presentamos los siguientes casos clinicos.

Results from a systematic research on the coherence (and inefficiencies) of current and alternative ways to exploit solar thermal energy are reported in this paper, intended to analyze forth and back the energy conversion chain from solar radiation to electricity. This exercise pointed out the pivotal role of the heat transfer fluid for an effective integration of said energy chain, and CO2 was selected for that role, because it is a gas without practical limitations in maximum temperature, and very adequate values of critical temperature and pressure. Optimum operating conditions were attainable in multi-tube receivers illuminated by advanced Linear Fresnel Reflectors with moderate values of radiation concentration factors; and the architecture of the full solar field system could be simplified in modular lattices leading to minimum values of mass requirements of the relevant materials, from glass to concrete. The specific investment cost for this new kind of power plant was evaluated in terms of said mass accountancy, and it was found that solar thermal power could be competitive with fossil fuel power plants in the near future.

A systematic analysis is presented of a CSP plant family based on: - A solar radiation concentrator according to the Advanced Fresnel linear mirror system which optimizes the ratio between captured radiation and weigh of the concentrator. - A receiver using dry air (at 10 MPa) as heat carrier fluid, working as a bunch of pipes with outstanding performances of thermal efficiency. - A low-losses receiver using air at a constant pressure of 0.1 MPa, with strong suppression of radiation and convection. - A plant layout with to separated regions, the inner one directly connected to the Power Block through a steam generator; and the outer region where hot air is driven to an intermediate heat exchanger where a stream of molten salt is heated, and collected, and sent to a second steam generator feeding the power block. - The molten salt streams can be stored as thermal energy storage, so that the plant can be fully regulated and could work after sunset. The main result is that a simple and robust design of CSP plants embodying a number of patents and other innovations can be identified as a main road to reach commercial maturity and to low down costs until becoming competitive with traditional energy sources. This technology is estimated to achieve annual efficiencies of 13%, in the same order of magnitude than parabolic trough collectors.

Linear Fresnel collectors are identified as a technology that should play a main role in order to reduce cost of Concentrating Solar Power. An optical and thermal analysis of the different blocks of the solar power plant is carried out, where Fresnel arrays are compared with the most extended linear technology: parabolic trough collectors. It is demonstrated that the optical performance of Fresnel array is very close to that of PTC, with similar values of maximum flux intensities. In addition, if the heat carrier fluid flows in series by the tubes of the receiver, relatively high thermal efficiencies are achieved. Thus, an annual solar to electricity efficiency of 19% is expected, which is similar to the state of the art in PTCs; this is done with a reduction of costs, thanks to lighter structures, that drives to an estimation of LCOE of around 6.5 c€/kWh.

A new reactor configuration is proposed under the requirements of providing a high value of breeding ratio and very high safety standards in all conditions, particularly in severe accidents. This double objective conveys the need of very fast neutron spectrum and the use of fuels with a relatively high content of transuranium nuclei, particularly plutonium isotopes. These facts define a narrow design window where a solution must be found to the safety problems created by the lack of Doppler effect and by a strong reduction in the percentage of delayed neutrons. The operational range in safe conditions almost vanishes, because of the lack of negative feedback mechanism and the very small reactivity margin before arriving to prompt-criticality. In order to improve operation conditions, the reactor is kept subcritical, and power level is kept constant with the help of an external source of neutrons, generated by spallations induced by accelerated protons. Main innovations are found in the fuel configuration, because the fuel is embodied into small disks with suitable cladding and different diameters, and the disks are fixed to a geometrical structure forming a virtual spherical surface or cage. The reactor core is therefore a pebble bed, but the pebbles are not actual pebbles, as already said, although they can be evacuated from the core by letting them fall down into a core catcher where subcriticality and decay heat cooling are guaranteed.

The efficiency of any thermal power plant is related to the maximum working temperature that some components can reach. Examples of material constraints are the first stage blades of a gas turbine or the receiver of a solar tower plant, but there are other temperature constraints, such as the ones related with the heat transfer fluid. Nowadays, this happens in the most common solar technology: parabolic trough collectors that use synthetic oil. This fluid must work below 400 °C. This limitation affects the power plant efficiency due to a poor Rankine cycle yield. To avoid this problem and go to higher temperatures, a gas can be used as heat transfer fluid, providing at the same time other significant advantages over synthetic oil: non-flammability and no environmental threats. The purpose of this paper is to justify the theoretical basis of the gas use in parabolic troughs and the problems related, and also to describe the test loop built at the PSA (Plataforma Solar de Almeria) in order to demonstrate the technical feasibility of this new technology, testing all components required to build a pre-commercial power plant. This paper describes the main features of this technology, the theoretical basis, the validation of the design tools and the results of the operation. Of them, the more important aspects are that high working pressure can reduce pumping power to adequate levels, that good controllability of the technology with hard solar transients can be achieved and that ball joints leaks problems detected appeared as the main inconvenience, but promising solution has been found.

The majority of commercial parabolic-trough plants in the world operate with synthetic oil as heat transfer fluid in the solar field. However, the synthetic oils that are available at affordable cost present some challenges such as their flammability, environmental toxicity and a temperature limitation of around 400 °C. As alternative, this work proposes the use of pressurized nitrogen as heat transfer fluid. In order to analyze the feasibility of this technology, a comparison between a plant with nitrogen and a conventional plant with synthetic oil has been carried out. In both cases, 50 MW e parabolic-trough plants with 6 h of thermal storage are used as reference. A performance model including the solar field, the thermal storage system and the power block has been developed for each plant in the TRNSYS simulation software. This paper also describes the specifications, design and sizing of the solar field and explains the basic operation strategy applied in each model. Both annual simulations have been performed considering the same location, Almeria (Spain), and meteorological data. In summary, the results show that similar net annual electricity productions can be attained for parabolic-trough plants with the same collection area using either nitrogen or synthetic oil as heat transfer fluid.

Tesis Doctoral leida en la Universidad Rey Juan Carlos de Madrid en 2015. Director de la Tesis: Manuel Romero Alvarez. Co-director: Javier Munoz Anton. Tutor: Raul Sanz Martin

Nowadays, parabolic trough collectors constitute the first concentrating solar thermal technology regarding global installed power. Central receivers and Fresnel receivers appear with smaller value and commercial solar dishes power are practically negligible. Several features have driven parabolic troughs to this first position, but some disadvantages are appearing, i.e. the cost reduction is not as quick as expected, the flexible or ball joints constitute leak problems with high pressure and temperature, and simplification of the mechanical structures is quite difficult. At this point, Fresnel receivers appear as a main competitor with troughs, offering lower cost but also lower efficiency; if the reduction in cost is higher than in efficiency, or if Fresnel efficiency is improved, there are potential facts which can make this simpler technology more competitive than trough collectors. In order to improve the Fresnel capabilities, it could be useful to analyze its optical properties. One important feature of Fresnel solar fields is that receiver and concentrator are mechanically separated, providing the system of a new freedom degree in comparison with trough collectors. This degree of freedom can be used in multi-tube receivers, using the high intensity thermal flux impinging in the receiver to illuminate the tubes where the fluid has higher film coefficient (i.e. where the phase change occurs) to obtain a high thermal efficiency, and using the lower thermal flux for preheating and reheating. The idea presented in this paper is to use a multi-tube Fresnel receiver with an adequate optical system that permits tailoring the thermal flux mapping in the receiver in coherence with the convection process of the thermal fluid. In order to obtain this objective, the mass flow will undergo preheating through the peripheral tubes (where the radiation flux will be lower due to the tracking, mirrors shape and sun shape errors) and will be driven afterwards to the high intensity thermal flux, where boiling (that implies high film coefficient values) takes place. A four tube receiver configuration, according to these ideas, will have two main possibilities. The first one a one-way mass flow through the peripheral tubes (inlets to the receiver) and a second pass inside the internal tubes (outlets). The second possibility assumes the mass-flow inlet receiver through one peripheral tube and the exit at the other one, the mass flow passing consecutively through the other two tubes.

Assessment of the practical implementation of systems for subsurface inter-seasonal storage and recovery of solar energy requires a modelling capability which can represent heat transfer processes at the soil surface, at depth in the soil profile, and within the energy collector system itself. This study presents initial findings related to the development of both analytical and numerical tools to represent various components of such inter-seasonal heat storage facilities. In particular two aspects are considered; firstly the use of widely available averaged meteorological data to be employed in an analytical solution of a simplified version of the problem and secondly the use of a more comprehensive finite element solution to explore the detailed thermal response of the ground in terms of seasonal energy storage. Initial comparisons against field measurements from a large scale demonstration project (undertaken by others) are presented and preliminary conclusions related to the key factors affecting the representation of the surface boundary condition made. The analytical approach developed appears to offer a representative and practical way of estimating initial conditions for both initial assessment of potential for energy collection and storage and for use in defining initial conditions in any subsequent numerical analysis of a detailed inter-seasonal heat storage facility.