Analytic optical design of linear Fresnel collectors with variable widths and shifts of mirrors

Linear Fresnel collectors still present a large margin to improve efficiency. Solar fields of this kind installed until current time, both prototypes and commercial plants, are designed with widths and shifts of mirrors that are constant across the solar field. However, the physical processes that limit the width of the mirrors depend on their relative locations to the receiver; the same applies to shading and blocking effects, that oblige to have a minimum shift between mirrors. In this work such phenomena are studied analytically in order to obtain a coherent design, able to improve the efficiency with no increase in cost. A ray tracing simulation along one year has been carried out for a given design, obtaining a moderate increase in radiation collecting efficiency in comparison to conventional designs. Moreover, this analytic theory can guide future designs aiming at fully optimizing linear Fresnel collectors' performance.

Entornos termodinámicos. Una cartografía crítica en torno a la energía y la arquitectura

En los últimos años, y a la luz de los retos a los que se enfrenta la sociedad, algunas voces están urgiendo a dejar atrás los paradigmas modernos —eficiencia y rendimiento— que sustentan a las llamadas prácticas sostenibles, y están alentando a repensar, en el contexto de los cambios científicos y culturales, una agenda termodinámica y ecológica para la arquitectura. La cartografía que presenta esta tesis doctoral se debe de entender en este contexto. Alineándose con esta necesidad, se esfuerza por dar a este empeño la profundidad histórica de la que carece. De este modo, el esfuerzo por dotar a la arquitectura de una agenda de base científica, se refuerza con una discusión cultural sobre el progresivo empoderamiento de las ideas termodinámicas en la arquitectura. Esta cartografía explora la historia de las ideas termodinámicas en la arquitectura desde el principio del siglo XX hasta la actualidad. Estudia, con el paso de los sistemas en equilibrio a los alejados del equilibrio como trasfondo, como las ideas termodinámicas han ido infiltrándose gradualmente en la arquitectura. Este esfuerzo se ha planteado desde un doble objetivo. Primero, adquirir una distancia crítica respecto de las prácticas modernas, de modo que se refuerce y recalibre el armazón intelectual y las herramientas sobre las que se está apoyando esta proyecto termodinámico. Y segundo, desarrollar una aproximación proyectual sobre la que se pueda fundamentar una agenda termodinámica para la arquitectura, asunto que se aborda desde la firme creencia de que es posible una re-descripción crítica de la realidad. De acuerdo con intercambios de energía que se dan alrededor y a través de un edificio, esta cartografía se ha estructurado en tres entornos termodinámicos, que sintetizan mediante un corte transversal la variedad de intercambios de energía que se dan en la arquitectura: -Cualquier edificio, como constructo espacial y material inmerso en el medio, intercambia energía mediante un flujo bidireccional con su contexto, definiendo un primer entorno termodinámico al que se denomina atmósferas territoriales. -En el interior de los edificios, los flujos termodinámicos entre la arquitectura y su ambiente interior definen un segundo entorno termodinámico, atmósferas materiales, que explora las interacciones entre los sistemas materiales y la atmósfera interior. -El tercer entorno termodinámico, atmosferas fisiológicas, explora los intercambios de energía que se dan entre el cuerpo humano y el ambiente invisible que lo envuelve, desplazando el objeto de la arquitectura desde el marco físico hacia la interacción entre la atmósfera y los procesos somáticos y percepciones neurobiológicas de los usuarios. A través de estos tres entornos termodinámicos, esta cartografía mapea aquellos patrones climáticos que son relevantes para la arquitectura, definiendo tres situaciones espaciales y temporales sobre las que los arquitectos deben actuar. Estudiando las conexiones entre la atmósfera, la energía y la arquitectura, este mapa presenta un conjunto de ideas termodinámicas disponibles —desde los parámetros de confort definidos por la industria del aire acondicionado hasta las técnicas de acondicionamiento pasivo— que, para ser efectivas, necesitan ser evaluadas, sintetizadas y recombinadas a la luz de los retos de nuestro tiempo. El resultado es un manual que, mediando entre la arquitectura y la ciencia, y a través de este relato histórico, acorta la distancia entre la arquitectura y la termodinámica, preparando el terreno para la definición de una agenda termodinámica para el proyecto de arquitectura. A este respecto, este mapa se entiende como uno de los pasos necesarios para que la arquitectura recupere la capacidad de intervenir en la acuciante realidad a la que se enfrenta. ABSTRACT During the last five years, in the light of current challenges, several voices are urging to leave behind the modern energy paradigms —efficiency and performance— on which the so called sustainable practices are relying, and are posing the need to rethink, in the light of the scientific and cultural shifts, the thermodynamic and ecological models for architecture. The historical cartography this PhD dissertation presents aligns with this effort, providing the cultural background that this endeavor requires. The drive to ground architecture on a scientific basis needs to be complemented with a cultural discussion of the history of thermodynamic ideas in architecture. This cartography explores the history of thermodynamic ideas in architecture, from the turn of the 20th century until present day, focusing on the energy interactions between architecture and atmosphere. It surveys the evolution of thermodynamic ideas —the passage from equilibrium to far from equilibrium thermodynamics— and how these have gradually empowered within design and building practices. In doing so, it has posed a double-objective: first, to acquire a critical distance with modern practices which strengthens and recalibrates the intellectual framework and the tools in which contemporary architectural endeavors are unfolding; and second, to develop a projective approach for the development a thermodynamic agenda for architecture and atmosphere, with the firm belief that a critical re-imagination of reality is possible. According to the different systems which exchange energy across a building, the cartography has been structured in three particular thermodynamic environments, providing a synthetic cross-section of the range of thermodynamic exchanges which take place in architecture: -Buildings, as spatial and material constructs immersed in the environment, are subject to a contiuous bidirectional flow of energy with its context, defining a the first thermodynamic environment called territorial atmospheres. -Inside buildings, the thermodynamic flow between architecture and its indoor ambient defines a second thermodynamic environment, material atmospheres, which explores the energy interactions between the indoor atmosphere and its material systems. -The third thermodynamic environment, physiological atmospheres, explores the energy exchanges between the human body and the invisible environment which envelopes it, shifting design drivers from building to the interaction between the atmosphere and the somatic processes and neurobiological perceptions of users. Through these three thermodynamic environments, this cartography maps those climatic patterns which pertain to architecture, providing three situations on which designers need to take stock. Studying the connections between atmosphere, energy and architecture this map presents, not a historical paradigm shift from mechanical climate control to bioclimatic passive techniques, but a range of available thermodynamic ideas which need to be assessed, synthesized and recombined in the light of the emerging challenges of our time. The result is a manual which, mediating between architecture and science, and through this particular historical account, bridges the gap between architecture and thermodynamics, paving the way to a renewed approach to atmosphere, energy and architecture. In this regard this cartography is understood as one of the necessary steps to recuperate architecture’s lost capacity to intervene in the pressing reality of contemporary societies.

A novel energy-driven computing paradigm for e-health scenarios

A first-rate e-Health system saves lives, provides better patient care, allows complex but useful epidemiologic analysis and saves money. However, there may also be concerns about the costs and complexities associated with e-health implementation, and the need to solve issues about the energy footprint of the high-demanding computing facilities. This paper proposes a novel and evolved computing paradigm that: (i) provides the required computing and sensing resources; (ii) allows the population-wide diffusion; (iii) exploits the storage, communication and computing services provided by the Cloud; (iv) tackles the energy-optimization issue as a first-class requirement, taking it into account during the whole development cycle. The novel computing concept and the multi-layer top-down energy-optimization methodology obtain promising results in a realistic scenario for cardiovascular tracking and analysis, making the Home Assisted Living a reality.

Effect of climate change on brown trout thermal habitat shifts along the river continuum.

X International Symposium on Ecohydraulics

Intermittent pluri-sink model and the emergence of complex heterogeneity patterns: a simple paradigm for explaining complexity in soil chemical distributions

The spatial complexity of the distribution of organic matter, chemicals, nutrients, pollutants has been demonstrated to have multifractal nature (Kravchenco et al. [1]). This fact supports the possibility of existence of some emergent heterogeneity structure built under the evolution of the system. The aim of this note is providing a consistent explanation to the mentioned results via an extremely simple model.

“You Can't Always Get What You Want” : A Novel Research Paradigm to Explore the Relationship between Multiple Intentions and Behaviours

Funded by •Centre for Translational Research in Public Health •United Kingdom Clinical Research Collaboration Public Health Research Centre •British Heart Foundation •Cancer Research United Kingdom •Economic and Social Research Council •Medical Research Council •National Institute for Health

On the classification of binary shifts of finite commutant index

We provide a complete classification up to conjugacy of the binary shifts of finite commutant index on the hyperfinite II1, factor. There is a natural correspondence between the conjugacy classes of these shifts and polynomials over GF(2) satisfying a certain duality condition.

Heterothermal acclimation: An experimental paradigm for studying the control of thermal acclimation in crabs

A method for the study of the control of the attainment of thermal acclimation has been applied to the crabs, Cancer pagurus and Carcinus maenas. Crabs were heterothermally acclimated by using an anterior–posterior partition between two compartments, one at 8°C and the other at 22°C. One compartment held a three-quarter section of the crab including the central nervous system (CNS), eye stalks, and ipsilateral legs; the other held a quarter section including the contralateral legs. Criteria used to assess the acclimation responses were comparisons of muscle plasma membrane fatty acid composition and “fluidity.” In both species, the major fatty acids of phosphatidylcholine were 16:0, 18:1, 20:5, and 22:6, whereas phosphatidylethanolamine contained significantly less 16:0 but more 18:0; these fatty acids comprised 80% of the total. Differences in fatty acid composition were demonstrated between fractions obtained from the ipsilateral and contralateral legs from the same heterothermally acclimated individual. In all acclimation states (except 22CNS, phosphatidylcholine fraction), membrane lipid saturation was significantly increased with acclimation at 22° as compared with 8°C. Membrane fluidity was determined by using 1,3-diphenyl-1,3,5 hexatriene (DPH) fluorescence polarization. In both species, membranes from legs held at 8° were more fluid than from legs held at 22°C irrespective of the acclimation temperature of the CNS. Heterothermal acclimation demonstrated that leg muscle membrane composition and fluidity respond primarily to local temperature and were not predominately under central direction. The responses between 8°C- and 22°C-acclimated legs were more pronounced when the CNS was cold-acclimated, so a central influence cannot be excluded.

Unusual 1H NMR chemical shifts support (His) Cɛ1—H⋅⋅⋅O⩵C H-bond: Proposal for reaction-driven ring flip mechanism in serine protease catalysis

13C-selective NMR, combined with inhibitor perturbation experiments, shows that the Cɛ1—H proton of the catalytic histidine in resting α-lytic protease and subtilisin BPN′ resonates, when protonated, at 9.22 ppm and 9.18 ppm, respectively, which is outside the normal range for such protons and ≈0.6 to 0.8 ppm further downfield than previously reported. They also show that the previous α-lytic protease assignments [Markley, J. L., Neves, D. E., Westler, W. M., Ibanez, I. B., Porubcan, M. A. & Baillargeon, M. W. (1980) Front. Protein Chem. 10, 31–61] were to signals from inactive or denatured protein. Simulations of linewidth vs. pH demonstrate that the true signal is more difficult to detect than corresponding signals from inactive derivatives, owing to higher imidazole pKa values and larger chemical shift differences between protonated and neutral forms. A compilation and analysis of available NMR data indicates that the true Cɛ1—H signals from other serine proteases are similarly displaced downfield, with past assignments to more upfield signals probably in error. The downfield displacement of these proton resonances is shown to be consistent with an H-bond involving the histidine Cɛ1—H as donor, confirming the original hypothesis of Derewenda et al. [Derewenda, Z. S., Derewenda, U. & Kobos, P. M. (1994) J. Mol. Biol. 241, 83–93], which was based on an analysis of literature x-ray crystal structures of serine hydrolases. The invariability of this H-bond among enzymes containing Asp-His-Ser triads indicates functional importance. Here, we propose that it enables a reaction-driven imidazole ring flip mechanism, overcoming a major dilemma inherent in all previous mechanisms, namely how these enzymes catalyze both the formation and productive breakdown of tetrahedral intermediates.

Microbial iron transport via a siderophore shuttle: A membrane ion transport paradigm

A mechanism of ion transport across membranes is reported. Microbial transport of Fe3+ generally delivers iron, a growth-limiting nutrient, to cells via highly specific siderophore-mediated transport systems. In contrast, iron transport in the fresh water bacterium Aeromonas hydrophila is found to occur by means of an indiscriminant siderophore transport system composed of a single multifunctional receptor. It is shown that (i) the siderophore and Fe3+ enter the bacterium together, (ii) a ligand exchange step occurs in the course of the transport, and (iii) a redox process is not involved in iron exchange. To the best of our knowledge, there have been no other reports of a ligand exchange mechanism in bacterial iron transport. The ligand exchange step occurs at the cell surface and involves the exchange of iron from a ferric siderophore to an iron-free siderophore already bound to the receptor. This ligand exchange mechanism is also found in Escherichia coli and seems likely to be widely distributed among microorganisms.

Identification of a second aryl phosphate-binding site in protein-tyrosine phosphatase 1B: A paradigm for inhibitor design

The structure of the catalytically inactive mutant (C215S) of the human protein-tyrosine phosphatase 1B (PTP1B) has been solved to high resolution in two complexes. In the first, crystals were grown in the presence of bis-(para-phosphophenyl) methane (BPPM), a synthetic high-affinity low-molecular weight nonpeptidic substrate (Km = 16 μM), and the structure was refined to an R-factor of 18.2% at 1.9 Å resolution. In the second, crystals were grown in a saturating concentration of phosphotyrosine (pTyr), and the structure was refined to an R-factor of 18.1% at 1.85 Å. Difference Fourier maps showed that BPPM binds PTP1B in two mutually exclusive modes, one in which it occupies the canonical pTyr-binding site (the active site), and another in which a phosphophenyl moiety interacts with a set of residues not previously observed to bind aryl phosphates. The identification of a second pTyr molecule at the same site in the PTP1B/C215S–pTyr complex confirms that these residues constitute a low-affinity noncatalytic aryl phosphate-binding site. Identification of a second aryl phosphate binding site adjacent to the active site provides a paradigm for the design of tight-binding, highly specific PTP1B inhibitors that can span both the active site and the adjacent noncatalytic site. This design can be achieved by tethering together two small ligands that are individually targeted to the active site and the proximal noncatalytic site.