Obtenció d'estruvita a partir de la fracció líquida digerida de purins de vaca

Actualment a Catalunya existeixen zones amb importants limitacions per l’aplicació de purins al sòl, pel que és imprescindible trobar alternatives de gestió i tractament que permetin l’aprofitament adequat dels recursos continguts a les dejeccions ramaderes sense afectar el medi. La digestió anaeròbia és una de les tècniques utilitzades en el tractament de les dejeccions ramaderes. L’efluent líquid que s’obté d’aquest tractament no modifica el contingut de nitrogen i fòsfor i per tant ha de ser gestionat correctament. L’objectiu general d’aquest projecte és avaluar la precipitació d’estruvita (sal de magnesi, amoni i fosfat) com una alternativa de gestió de l’efluent líquid d’una planta de digestió anaeròbia i compostatge que tracta dejeccions ramaderes conjuntament amb altres residus orgànics. S’han avaluat els efectes dels diferents paràmetres operacionals en la formació d’estruvita (pH, temperatura, velocitat d’agitació, alcalinitat), mitjançant assaigs en discontinu amb solució sintètica. A continuació s’ha procedit a obtenir estruvita a partir de la fracció líquida digerida de purí (FLD), en assaigs en discontinu per estudiar l’efecte del contingut de matèria orgànica i sòlids Totals (ST), així com el contingut en fosfats i el pH de reacció. Finalment, s’han optimitzat els paràmetres de procés en continu, mitjançant la posada en marxa d’un reactor a escala de laboratori i estudi de l’efecte de la velocitat d’agitació i de la introducció del stripping de CO2, tant amb solució sintètica com amb la fracció líquida digerida del purí. Dels resultats obtinguts es pot concloure que els factors que tenen una major influència en el procés d’obtenció d’estruvita són el pH (el pH òptim es situa al voltant de 9), i la presència de matèria orgànica i sòlids ens suspensió, que interfereix de forma quantitativa i qualitativa en la formació de l’estruvita. En el procés en continu s’ha aconseguit reduccions d’un 84% i 98% d’amoni i fòsfor respectivament, obtenintse estruvita que pot ser utilitzada com a fertilitzant d’alliberació lenta. Es pot concloure que la precipitació d’estruvita és una bona alternativa per millorar la gestió de les dejeccions ramaderes alhora que permet recuperar nutrients i tancar cicles. La combinació amb un tractament previ que elimini la matèria orgànica, com podria ser la digestió anaeròbia, i una separació de fases, per eliminar els sòlids en suspensió, es presenta com una configuració amb molts avantatges.

Enhanced radar precipitation estimates using a combined clutter and beam blockage correction technique

Weather radar observations are currently the most reliable method for remote sensing of precipitation. However, a number of factors affect the quality of radar observations and may limit seriously automated quantitative applications of radar precipitation estimates such as those required in Numerical Weather Prediction (NWP) data assimilation or in hydrological models. In this paper, a technique to correct two different problems typically present in radar data is presented and evaluated. The aspects dealt with are non-precipitating echoes - caused either by permanent ground clutter or by anomalous propagation of the radar beam (anaprop echoes) - and also topographical beam blockage. The correction technique is based in the computation of realistic beam propagation trajectories based upon recent radiosonde observations instead of assuming standard radio propagation conditions. The correction consists of three different steps: 1) calculation of a Dynamic Elevation Map which provides the minimum clutter-free antenna elevation for each pixel within the radar coverage; 2) correction for residual anaprop, checking the vertical reflectivity gradients within the radar volume; and 3) topographical beam blockage estimation and correction using a geometric optics approach. The technique is evaluated with four case studies in the region of the Po Valley (N Italy) using a C-band Doppler radar and a network of raingauges providing hourly precipitation measurements. The case studies cover different seasons, different radio propagation conditions and also stratiform and convective precipitation type events. After applying the proposed correction, a comparison of the radar precipitation estimates with raingauges indicates a general reduction in both the root mean squared error and the fractional error variance indicating the efficiency and robustness of the procedure. Moreover, the technique presented is not computationally expensive so it seems well suited to be implemented in an operational environment.

Citizens' control and the efficiency of local public services

Està àmpliament acceptat que la descentralització fiscal incrementa el control dels ciutadans sobre els polítics, fomenta el rendiment de comptes i augmenta l¿eficiència. Aquest treball té per objectiu identificar les característiques socio-econòmiques dels ciutadans (votants potencials) que generen un major control sobre els responsables polítics locals provocant, així, un major nivell d'eficiència en un context descentralitzat.També s'analitzen les característiques fiscals dels governs locals que fomenten aquest control i eficiència. L'estudi s'ha aplicat a una mostra de municipis catalans seguint la metodologia convencional basada en l'estimació en dues etapes. A la primera etapa s'estima l'eficiència en que operen els municipis mitjançant la tècnica DEA. La novetat rau en el càlcul d'una nova versió d'indicador global d¿output municipal. En la segona etapa, a través d¿una estimació tipus Tobit (models censurats) i de mètodes bootstrap, es mostra com els factors abans comentats poden influir sobre l¿eficiència. Els resultats suggereixen que la forta presencia de comerciants, jubilats i persones amb dret a vot afavoreixen el control dels ciutadans, el rendiment de comptes i l¿eficiència. Un factor que facilita aquest control, i per tant una major eficiència, és la presència de baixos costos d'oportunitat d'obtenir informació sobre la gestió local dels serveis públics.

Measuring the efficiency in Spanish municipal refuse collection services

The objective of this study is to analyse the technical or productive efficiency ofthe refuse collection services in 75 municipalities located in the Spanish regionof Catalonia. The analysis has been carried out using various techniques. Firstly we have calculated a deterministic parametric frontier, then a stochastic parametric frontier, and finally, various non-parametric approaches (DEA and FDH). Concerning the results, these naturally differ according to the technique used to approach the frontier. Nevertheless, they have an appearance of solidity, at least with regard to the ordinal concordance among the indices of efficiency obtained by the different approaches, as is demonstrated by the statistical tests used. Finally, we have attempted to search for any relation existing between efficiency and the method (public or private) of managing the services. No significant relation was found between the type of management and efficiencyindices

Citizens' control and the efficiency of local public services

Està àmpliament acceptat que la descentralització fiscal incrementa el control dels ciutadans sobre els polítics, fomenta el rendiment de comptes i augmenta l¿eficiència. Aquest treball té per objectiu identificar les característiques socio-econòmiques dels ciutadans (votants potencials) que generen un major control sobre els responsables polítics locals provocant, així, un major nivell d'eficiència en un context descentralitzat.També s'analitzen les característiques fiscals dels governs locals que fomenten aquest control i eficiència. L'estudi s'ha aplicat a una mostra de municipis catalans seguint la metodologia convencional basada en l'estimació en dues etapes. A la primera etapa s'estima l'eficiència en que operen els municipis mitjançant la tècnica DEA. La novetat rau en el càlcul d'una nova versió d'indicador global d¿output municipal. En la segona etapa, a través d¿una estimació tipus Tobit (models censurats) i de mètodes bootstrap, es mostra com els factors abans comentats poden influir sobre l¿eficiència. Els resultats suggereixen que la forta presencia de comerciants, jubilats i persones amb dret a vot afavoreixen el control dels ciutadans, el rendiment de comptes i l¿eficiència. Un factor que facilita aquest control, i per tant una major eficiència, és la presència de baixos costos d'oportunitat d'obtenir informació sobre la gestió local dels serveis públics.

Measuring the efficiency in Spanish municipal refuse collection services

The objective of this study is to analyse the technical or productive efficiency ofthe refuse collection services in 75 municipalities located in the Spanish regionof Catalonia. The analysis has been carried out using various techniques. Firstly we have calculated a deterministic parametric frontier, then a stochastic parametric frontier, and finally, various non-parametric approaches (DEA and FDH). Concerning the results, these naturally differ according to the technique used to approach the frontier. Nevertheless, they have an appearance of solidity, at least with regard to the ordinal concordance among the indices of efficiency obtained by the different approaches, as is demonstrated by the statistical tests used. Finally, we have attempted to search for any relation existing between efficiency and the method (public or private) of managing the services. No significant relation was found between the type of management and efficiencyindices

An application of capital allocation principles to operational risk

The cost of operational risk refers to the capital needed to a fford the loss generated by ordinary activities of a firm. In this work we demonstrate how allocation principles can be used to the subdivision of the aggregate capital so that the firm can distribute this cost across its various constituents that generate operational risk. Several capital allocation principles are revised. Proportional allocation allows to calculate a relative risk premium to be charged to each unit. An example of fraud risk in the banking sector is presented and some correlation scenarios between business lines are compared. Keywords: solvency, quantile, value at risk, copulas

Efficiency of informational transfer in regular and complex networks

We analyze the process of informational exchange through complex networks by measuring network efficiencies. Aiming to study nonclustered systems, we propose a modification of this measure on the local level. We apply this method to an extension of the class of small worlds that includes declustered networks and show that they are locally quite efficient, although their clustering coefficient is practically zero. Unweighted systems with small-world and scale-free topologies are shown to be both globally and locally efficient. Our method is also applied to characterize weighted networks. In particular we examine the properties of underground transportation systems of Madrid and Barcelona and reinterpret the results obtained for the Boston subway network.

Ownership change and banking efficiency in the new EU members

The aim of this study is to analyze how European integration and, especially, changes in ownership, has affected banking efficiency in Central and Eastern European countries which have recently experimented this process more intensely. Using a stochastic frontier approach (SFA) applied to panel data, we have estimated bank efficiency levels in a sample of 189 banks from 12 countries during the period 2000 to 2008 and we have analyzed the influence of some bank characteristics on these efficiency levels. The results show that European integration has significantly improved the cost efficiency of banks in these countries but profit efficiency has significantly decreased. We have found very small differences between different ownership types and only a very small impact of foreign ownership on cost efficiency, showing that the entry of foreign ownership is not enough to explain the significant variations in banking efficiency after the accession.

Effects of CPAP on oxidative stress and nitrate efficiency in sleep apnoea: a randomised trial.

Background: Previous studies have presented contradictory data concerning obstructive sleep apnoea syndrome (OSAS), lipid oxidation and nitric oxide (NO) bioavailability. This study was undertaken to (1) compare the concentration of 8-isoprostane and total nitrate and nitrite (NOx) in plasma of middle-aged men with OSAS and no other known co-morbidity and healthy controls of the same age, gender and body mass index; and (2) test the hypothesis that nasal continuous positive airway pressure (CPAP) therapy attenuates oxidative stress and nitrate deficiency. Methods: A prospective, randomised, placebo controlled, double-blind, crossover study was performed in 31 consecutive middle-aged men with newly diagnosed OSAS and 15 healthy control subjects. Patients with OSAS were randomised to receive sham CPAP or effective CPAP for 12 weeks. Blood pressure, urinary catecholamine levels and plasma 8-isoprostane and NOx concentrations were obtained before and after both treatment modalities. Results: Patients with OSAS had significantly higher 8-isoprostane levels (median (IQR) 42.5 (29.2-78.2) vs 20.0 (12.5-52.5) pg/ml, p = 0.041, Mann-Whitney test) and lower NOx levels (264 (165-650) vs 590 (251- 1465) mmol/l, p = 0.022) than healthy subjects. Body mass index, blood pressure and urinary catecholamines were unchanged by CPAP therapy, but 8-isoprostane concentrations decreased (38.5 (24.2-58.7) pg/ml at baseline vs 22.5 (16.2-35.3) pg/ml on CPAP, p = 0.0001) and NOx levels increased (280 (177-707) vs 1373 (981-1517) mmol/l, p = 0.0001) after CPAP. Conclusions: OSAS is associated with an increase in oxidative stress and a decrease in NOx that is normalised

Bacterial adhesion efficiency on implant abutments: a comparative study

The attachment of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 28213 onto six different materials used to manufacture dental implant abutments was quantitatively determined after 2 and 24 h of contact between the materials and the bacterial cultures. The materials were topographically characterized and their wettability determined, with both parameters subsequently related to bacterial adhesion. Atomic force microscopy, interferometry, and contact angle measurement were used to characterize the materials" surfaces. The results showed that neither roughness nor nano-roughness greatly influenced bacterial attachment whereas wettability strongly correlated with adhesion. After 2 h the degree of E. coli attachment markedly differed depending on the material whereas similar differences were not observed for S. aureus, which yielded consistently higher counts of adhered cells. Nevertheless, after 24 h the adhesion of the two species to the different test materials no longer significantly differed, although on all surfaces the numbers of finally adhered E. coli were higher than those of S. aureus

The efficiency of indicator groups for the conservation of amphibians in the Brazilian Atlantic Forest

The adequate selection of indicator groups of biodiversity is an important aspect of the systematic conservation planning. However, these assessments differ in the spatial scale, in the methods used and in the groups considered to accomplish this task, which generally produces contradictory results. The quantification of the spatial congruence between species richness and complementarity among different taxonomic groups is a fundamental step to identify potential indicator groups. Using a constructive approach, the main purposes of this study were to evaluate the performance and efficiency of eight potential indicator groups representing amphibian diversity in the Brazilian Atlantic Forest. Data on the geographic range of amphibian species that occur in the Brazilian Atlantic Forest was overlapped to the full geographic extent of the biome, which was divided into a regular equal-area grid. Optimization routines based on the concept of complementarily were applied to verify the performance of each indicator group selected in relation to the representativeness of the amphibians in the Brazilian Atlantic Forest as a whole, which were solved by the algorithm"simulated annealing", through the use of the software MARXAN. Some indicator groups were substantially more effective than others in regards to the representation of the taxonomic groups assessed, which was confirmed by the high significance of data (F = 312.76; p < 0.01). Leiuperidae was considered as the best indicator group among the families analyzed, as it showed a good performance, representing 71% of amphibian species in the Brazilian Atlantic Forest (i.e. 290 species), which may be associated with the diffuse geographic distribution of its species. This study promotes understanding of how the diversity standards of amphibians can be informative for systematic conservation planning on a regional scale.

Efficiency and reliability enhancement of silicon nanocrystal field-effect luminescence from nitride-oxide gate stacks

We report on a field-effect light emitting device based on silicon nanocrystals in silicon oxide deposited by plasma-enhanced chemical vapor deposition. The device shows high power efficiency and long lifetime. The power efficiency is enhanced up to 0.1 %25 by the presence of a silicon nitride control layer. The leakage current reduction induced by this nitride buffer effectively increases the power efficiency two orders of magnitude with regard to similarly processed devices with solely oxide. In addition, the nitride cools down the electrons that reach the polycrystalline silicon gate lowering the formation of defects, which significantly reduces the device degradation.

Comparing assays for the measurement of AhR ligand activity

In this thesis (TFG) the results of the comparison of three assays for the measurement of AhR ligand activity are exposed. This study was part of a collaborative project aiming at the characterization of the AhR signaling activities of known naturally occurring compounds to explore the potential of using non-toxic compounds to treat inflammatory diseases via oral administration. The first goal of this project was to find an assay able to measure AhR-activity, so the comparison of different assays has been done in order to find the most convenient one according to the efficiency, sensitivity and precision. Moreover, other elements with operational nature such as price, toxicity of components or ease of use has been considered. From the use of compounds known from the literature to be AhR ligands, three assays have been tested: (1) P450-GloTM CYP1A2 Induction/Inhibition assay, (2) quantitative Polymerase Chain Reaction (qPCR) and (3) DR. CALUX® Bioassay. Moreover, a different experiment using the last assay was performed for the study in vivo of the transport of the compounds tested. The results of the TFG suggested the DR. CALUX® Bioassay as the most promising assay to be used for the screening of samples as AhR-ligands because it is quicker, easier to handle and less expensive than qPCR and more reproducible than the CYP1A2 Induction/Inhibition assay. Moreover, the use of this assay allowed having a first idea of which compounds are uptaken by the epithelial barrier and in with direction the transport happens.

Operational Cost Reduction in WDM Networks using Lighttours

Wavelength division multiplexing (WDM) networks have been adopted as a near-future solution for the broadband Internet. In previous work we proposed a new architecture, named enhanced grooming (G+), that extends the capabilities of traditional optical routes (lightpaths). In this paper, we compare the operational expenditures incurred by routing a set of demands using lightpaths with that of lighttours. The comparison is done by solving an integer linear programming (ILP) problem based on a path formulation. Results show that, under the assumption of single-hop routing, almost 15% of the operational cost can be reduced with our architecture. In multi-hop routing the operation cost is reduced in 7.1% and at the same time the ratio of operational cost to number of optical-electro-optical conversions is reduced for our architecture. This means that ISPs could provide the same satisfaction in terms of delay to the end-user with a lower investment in the network architecture