Convergence Properties of the Likelihood of Computed Dynamic Models

This paper studies the econometrics of computed dynamic models. Since these models generally lack a closed-form solution, their policy functions are approximated by numerical methods. Hence, the researcher can only evaluate an approximated likelihood associated with the approximated policy function rather than the exact likelihood implied by the exact policy function. What are the consequences for inference of the use of approximated likelihoods? First, we find conditions under which, as the approximated policy function converges to the exact policy, the approximated likelihood also converges to the exact likelihood. Second, we show that second order approximation errors in the policy function, which almost always are ignored by researchers, have first order effects on the likelihood function. Third, we discuss convergence of Bayesian and classical estimates. Finally, we propose to use a likelihood ratio test as a diagnostic device for problems derived from the use of approximated likelihoods.

Convergence Properties of the Likelihood of Computed Dynamic Models

This paper studies the econometrics of computed dynamic models. Since these models generally lack a closed-form solution, economists approximate the policy functions of the agents in the model with numerical methods. But this implies that, instead of the exact likelihood function, the researcher can evaluate only an approximated likelihood associated with the approximated policy function. What are the consequences for inference of the use of approximated likelihoods? First, we show that as the approximated policy function converges to the exact policy, the approximated likelihood also converges to the exact likelihood. Second, we prove that the approximated likelihood converges at the same rate as the approximated policy function. Third, we find that the error in the approximated likelihood gets compounded with the size of the sample. Fourth, we discuss convergence of Bayesian and classical estimates. We complete the paper with three applications to document the quantitative importance of our results.computed dynamic models, likelihood inference, asymptotic properties

Catching the Sugars: Electrochemical Aptasensors for the Detection of Cancer-Related Glycosylation Changes in Prostate-Specific Antigen

Prostate-specific Antigen (PSA) is the biomarker that is used for prostate cancer (PCa) detection, although its lack of specificity results in a high rate of false-positives and many unnecessary biopsies. Therefore, there is a need for more specific cancer biomarkers for PCa. Recent studies have shown that the aberrant glycosylation of proteins is a common feature of the presence of cancer. In the case of prostate cancer, there are changes in core-fucose and sialic acids in the glycan structure of PSA. In this work, we describe two different strategies to direct the selection of aptamers toward the glycans of PSA. From these strategies, we identified two aptamers (PSA-1 and PSAG-1) that bind to the glycan structure of PSA with high affinity. Both aptamers were applied in the design of electrochemical aptasensors, in sandwich and direct formats, in order to detect the changes in the glycosylation of PSA. The sensors responded to different levels of PSA in serum, and they showed higher potential to discriminate clinically-meaningful PCa than the ELISA (Enzyme-linked immunosorbent assay) test used in hospitals (reducing the number of false positives), although validation on more samples is needed

The Effect of the Spanish Nuclear Phase-out on the Electricity Market

Portugal and Spain are integrated into what is known as the Iberian Electricity Market. Spain participates in this market with significant contribution of energy produced by nuclear plants. In 2022, nuclear energy accounted for 22 % of the total energy generated in Spain. Nuclear power plants sell their energy largely through bilateral contracts, and approximately 20 % is offered in the day-ahead electricity market. By 2035, Spain will phase-out nuclear power producing a structural change of its generation mix. In this paper, we investigate the effect on the day-ahead Iberian electricity market that the gradual removal of nuclear power plants will have on the daily electricity market. The methodology is based on a ceteris paribus approach, where generation conditions are modified by removing nuclear plants and keeping the rest of the variables constant (demand and other generation). Under these conditions, the market is reproduced, estimating how electricity prices change in the day-ahead electricity market. To evaluate the market electricity prices under this new scenario with a total or a partial elimination of nuclear energy generation, it is necessary to use a market model. The existing literature shows various approaches to replicate the electricity market, among which are agent-base modelling, optimization algorithms, artificial intelligence techniques or metaheuristic merit-order methods. Our approach is based on the latter methods, by using actual generation and demand data, the new market generation and demand curves are reconstructed and the new clearing price is obtained. For the most conservative scenario, the results show a price increase of more than 5 % for the first 6 months of 2021. The reason for this increase is that nuclear generation participates in the market by offering its energy at prices close to zero. When this generation is withdrawn, there is a shift to the left of the hourly generation curve producing a new market equilibrium at a point of higher price and lower energy

Resilience of water supply systems – case study of Quinta do Lago

On the South of Portugal, namely in Quinta do Lago – Algarve the water consumption pattern changes from winter to summer, mainly due to the seasonality of touristic occupation and irrigation of green areas. In Quinta do Lago many plots have boreholes to extract groundwater for irrigation, however in summer, when the irrigation demand has its peak, the groundwater table lowers and it is observed saline intrusion into the aquifer. The increased concentration of salts in groundwater also increases the water demand for irrigation as the soil lixiviation must be attended. This phenomenon forces the owners to irrigate the private green areas with fresh water from the water supply system. In the last years, the number of plots irrigated with fresh water has increased and the current trend may cause the failure of the water supply system. In the present study the hydraulic and operational performance of the water supply system of Quinta do Lago is assessed, considering the increase on water demand for the irrigation of the private green areas. The used methodology is based on the hydraulic modelling of the water supply system and evaluation of performance indicators using penalty functions. From the analysis it is pointed out that undertaking appropriate operational modes, the water supply system may be resilient to the increase in water demand and investment in new infrastructure to attend this phenomenon may not be required.info:eu-repo/semantics/publishedVersio

Profitability Assessment of Windfarm Overplanting in Spain

The efforts made by European institutions to decarbonise the electricity system over the last decade have led Spain to become the fifth country in the world in terms of wind power plant capacity in 2021. This major achievement is still far from being able to contain and limit CO2 emissions. By 2030, it is expected that, together with photovoltaic energy, Spain will reach 74 % of renewable generation in its electricity system. Wind technology is currently very mature in onshore wind farms and its relatively low cost makes this technology attractive to investors. However, the best wind sites were the first places to be occupied by the first turbine generations. On the other hand, newer wind farms occupy sites with less wind resource but have more efficient turbines. To improve the profitability of the wind farm and increase its production, the feasibility of other alternatives such as overplanting or storage is beginning to be investigated. Overplanting aims to optimise the use of the transmission system by increasing wind capacity above the transmission capacity limit. In this work, we measure the profitability of an overplanting strategy by quantifying the parameters that make profitable the investment. The developed model optimised the production of energy taking into account technical and financial parameters in order to cover a wide range of situations. We analysed the case of a specific site with 25 2 MW turbines with the Python tool PyWake. The results obtained show that for each new turbine the annual energy produced (AEP) grows by around 3.87 GWh per turbine added (a cut of 1.69 GWh due to congestion of the transmission system). The study shows improvements in profitability when the electricity price exceeds 70 €/MWh

Antifungal activity of eukaryotic microalgae extracts in dermatophytes

Introduction: Microalgae are considered a promising source of biologically active secondary metabolites, with several biotechnological properties already recorded, including antifungal activity. Objective: Thus, the properties of ethanol extracts of microalgae Ankistrodesmus falcatus, Chaetoceros neogracilis, Desmodesmus brasiliensis, Dunaliella tertiolecta, Kirchneriella lunaris and Tetraselmis gracilis were investigated in vitro for antifungal activity against dermatophytes Nannizzia gypsea, Nannizzia nana, Trichophyton mentagrophytes and Trichophyton tonsurans. Methods: The extracts were evaluated using broth microdilution methodology, with a test interval of 0.0115 to 6 mg mL-1. The antifungal itraconazole was tested at concentrations 0.0313 to 16 μg mL-1. Results: All microalgae extracts showed antifungal activity, especially extracts from C. neogracilis, D. brasiliensis and K. lunaris that totally inhibited growth of all species of dermatophytes evaluated. The lowest MIC values recorded were for the extracts of D. brasiliensis and K. lunaris (MIC 0.188 mg mL-1), against T. tonsurans e N. nana. Conclusions: This was a pioneering work about the antifungal activity of these microalgae against dermatophytes. It is expected that, from this study, further research will be carried out in order to identify and isolate the active biomolecules responsible for the antifungal activity of these microalgae species.Introdução: as microalgas são consideradas uma fonte promissora de metabólitos secundários biologicamente ativos, com diversas propriedades biotecnológicas já registradas, incluindo atividade antifúngica. Objetivo: assim, as propriedades dos extratos etanólicos das microalgas Ankistrodesmus falcatus, Chaetoceros neogracilis, Desmodesmus brasiliensis, Dunaliella tertiolecta, Kirchneriella lunaris e Tetraselmis gracilis foram investigadas in vitro quanto à atividade antifúngica frente aos dermatófitos Nannizzia gypsea, Nannizzia nana, Trichophyton mentagrophytes e Trichophyton tonsurans. Metodologia: os extratos foram avaliados através da metodologia de microdiluição em caldo, com intervalo teste de 11.5 a 6.000 μg mL-1. O antifúngico itraconazol foi testado nas concentrações 0.0313 a 16 μg mL-1. Resultados: todos os extratos microalgais apresentaram atividade antifúngica, com destaque para os extratos das microalgasC. neogracilis, D. brasiliensis e K. lunaris, que inibiram totalmente o crescimento de todas as espécies de dermatófitos avaliadas. Os menores valores de CIM registrados foram para os extratos de D. brasiliensis e K. lunaris (CIM 188 μg mL-1), contra T. tonsurans e N. nana. Conclusão: este foi um trabalho pioneiro acerca da atividade antifúngica destas microalgas frente à dermatófitos. Espera-se que, a partir deste estudo, novas pesquisas sejam realizadas a fim de identificar e isolar as biomoléculas ativas responsáveis pela atividade antifúngica destas espécies de microalgas

Applied Geography

[EN] Lakes with strong variations in their water coverage may act as in dicators of different natural phenomena. Recent techniques for the extraction of Satellite-Derived Shorelines (SDSs) with subpixel accuracy are potentially useful for accurate and continuous monitoring of the limits of water bodies along large periods. This work proposes a method for combining the shoreline position with a digital elevation model to assign elevation values to the points defining the SDSs along the period 1984¿2020 in the shallow Gallocanta Lake (NE Iberian Peninsula). The relationship between the water surface and the elevation allows modeling the phenomena of lake changes as well as an estimation of the volume. The obtained data enables analyzing size and elevation changes of the water surface and the volumetric changes of the lake over more than three decades with a sub-weekly frequency (2¿5 days). The results constitute a valuable data package for robust analysis of lake trends. In the short term, the methodology provides sufficient precision to capture the changes caused by single meteorological events such as rainfall, even of small magnitude. The method constitutes a novel approach for curate hydric monitoring of lakes and water bodies, along large terrtories without requiring continuous in situ data acquisition.Support This research has been supported by the projects 'Monitorizacion de precision de las fluctuaciones de agua de humedales salinos intermitentes RAMSAR en la cuenca media del Ebro mediante teledeteccion espacial' with the financial support of Fundacion Biodiversidad from the Spanish Ministry for Ecological Transition and the Demographic Challenge (MITECO), PCI2018-092999 (AQUASALT) funded by MCIN/AEI/10.13039/501100011033 and co-funded by European Union, AQ-01.2021 (IRENE) funded by the Government of Aragon, MONOBESAT (PID2019-111435RB-I00) funded by the Spanish Ministry of Science, Innovation and Universities, and the Margarita Salas contract within the Re-qualification programme by the Spanish Ministry of Universities financed by the European Union-NextGenerationEU. This is a contribution to Research Group RNM 328 of the Andalusian Research Plan (PAI), and to CSIC Interdisciplinary Thematic Platform (PTI) Tele-deteccion (PTI-TELEDETECT). ESA and USGS provided access to the satellite imagery. The Spanish Meteorological Agency (AEMET) provided data after contract no. L2990130734. The Ebro River-Basin Authority (CHE) provided the water level data.Palomar-Vázquez, J.; Cabezas-Rabadán, C.; Castañeda, C.; Gracia, FJ.; Fernández-Sarría, A.; Priego De Los Santos, E.; Pons Crespo, R.... (2022). Inferring volumetric changes at a shallow lake from subpixel satellite-derived shorelines. Applied Geography. 149(102792):1-10. https://doi.org/10.1016/j.apgeog.2022.10279211014910279