A Bilevel Approach to Optimal Price-Setting of Time-and-Level-of-Use Tariffs

Time-and-Level-of-Use (TLOU) is a recently proposed pricing policy for energy, extending Time-of-Use with the addition of a capacity that users can book for a given time frame, reducing their expected energy cost if they respect this self-determined capacity limit. We introduce a variant of the TLOU defined in the literature, aligned with the supplier interest to prevent unplanned over-consumption. The optimal price-setting problem of TLOU is defined as a bilevel, bi-objective problem anticipating user choices in the supplier decision. An efficient resolution scheme is developed, based on the specific discrete structure of the lower-level user problem. Computational experiments using consumption distributions estimated from historical data illustrate the effectiveness of the proposed framework

Validación de un nuevo método de preconcentración y medición de mercurio en sedimentos utilizando materiales sol-gel dopados con extractantes sulfurados

El mercurio es un metal pesado altamente tóxico presente en el ambiente por causas naturales o antropogénicas. El mercurio contenido en los cuerpos receptores de agua tiende a precipitarse y acumularse en los sedimentos. Por lo tanto, las mediciones de mercurio en sedimentos representan un buen indicativo de la calidad del ecosistema. En este trabajo se presentan las diferentes etapas involucradas en el desarrollo de un nuevo método de separación, preconcentración y medición de mercurio en sedimentos con contenidos naturales de este elemento. La separación y preconcentración se realizó mediante el uso de nuevos materiales sorbentes preparados a través del proceso sol-gel utilizando CYANEX 471X (sulfuro de triisobutilfosfina) y CYANEX 301 (ácido bis (2,4,4-trimetilpentil) ditiofosfínico) como extractantes de mercurio. Se describe la optimización de la etapa de acoplamiento de los materiales empacados en columna, utilizando un sistema automatizado de inyección de flujo, para conectarla en línea con un espectrómetro de absorción atómica donde se realizó la medición de mercurio por generación de vapor frío. Como parte importante en el desarrollo de un nuevo método analítico, se encuentra su validación, la cual es materia de este trabajo. Por lo tanto, una vez optimizado, el método fue validado evaluando los siguientes parámetros: robustez, intervalo lineal y de trabajo, límite de detección y de cuantificación, selectividad, exactitud (repetibilidad y veracidad) e incertidumbre. El método fue aplicado para la medición de mercurio en un sedimento de presa con contenidos naturales de este analito. Los resultados se compararon con los obtenidos mediante espectrometría de masas con plasma inductivamente acoplado (ICP-MS) y espectrometría de fluorescencia atómica con generación de vapor frío (CV-AFS

La agroecología en Venezuela: Tensiones entre el rentismo petrolero y la soberanía agroalimentaria

The evolution of the agroecological wisdom is established in three periods, with special emphasis on the emergence and institutionalization of agroecology as a transdisciplinary framework. Agroecology, understood from the perspective of environmentally healthy food production system and adapted to natural cycles, is present, since the country has had important contributions from indigenous cultures, and African and European influences during the colonial period. The appearance of oil in early 20Th century, followed by the northamerican promoted agro-industrial model insertion, determined drastic changes towards a dependency on imported food policies and capital-intensive agriculture. Massive peasant migration conforming misery city belts worsen food production situation. However, towards the end of the century, urban environmentalist movements and academic sectors in synergy with conscious rural groups promoted the sustainable agriculture approach.The 1999 Constitution propitiated new institutions conceived to elaborate agricultural policies dispose to incorporate the agroecological wisdom. Currently, agroecology has powerful academic and institutional structures and is widely accepted by urban and rural social movements. Nevertheless, tensions with the oil dependency phantom and mechanistic-based scientific progress notions are notorious in the public policies of the national agroalimentary model, representing a real challenge for those groups fighting for sustainable agricultural option.La evolución del pensamiento agroecológico en Venezuela es planteada en tres grandes etapas, haciéndose especial énfasis en la emergencia e institucionalización de la agroecología como cuerpo de conocimiento transdisciplinario. Entendida la agroecología desde la perspectiva de la producción de alimentos con mínimo impacto sobre los ciclos naturales, y adaptada a los ecosistemas, ha estado presente, en tanto el país cuenta con importantes aportes de las culturas indígenas y la influencia africana y europea durante el período colonial. La aparición del petróleo a principios del siglo XX, y la posterior inserción del modelo agroindustrial significó un viraje que favoreció la fuerte dependencia alimentaria externa y la consolidación de una agricultura capital-intensiva. Esto se agudizó con la disminución inducida de una masa campesina que se vio compelida a formar parte de cinturones de miseria en pueblos y ciudades. No obstante, corrientes ambientalistas durante las últimas décadas, y la acción de grupos académicos e incluso urbanos en sinergia con grupos rurales conscientes, favorecen la agricultura sustentable. Con la Constitución de 1999 se generan nuevos ámbitos institucionales que propenden al diseño de políticas agrícolas que abren espacios al pensamiento agroecológico. Actualmente, la agroecología tiene potentes formas académicas e institucionales y es ampliamente aceptada por los movimientos sociales urbanos y rurales; no obstante, las tensiones con el fantasma del rentismo petrolero y las nociones de progreso científico de base mecanicista aún son manifiestas en las políticas públicas del modelo agroalimentario nacional, lo cual significa un reto todavía vivo para los grupos que luchan por una agricultura sustentable

Ventilatory threshold prediction by spectral analysis of heart rate variability in incremental maximal tests

Ventilatory thresholds (VT1 and VT2) are useful in many fields of medicine and sports. Nevertheless, their measurement is cumbersome and needs trained personnel. This work proposes an alternative method to predict VT1, VT2 and maximum loads in incremental maximal tests based on heart rate variability (HRV) analysis. Twelve competitive male cyclists executed an incremental exhaustive test. During the test, RR time series and gas concentrations were recorded. After artifact correction the power spectrum was estimated in a sliding window, and central frequency (CF) and bandwidth that contains half the total power (BW) were computed. An automatic algorithm recognized the loads where CF and BW undergo a significant change. These loads were used as inputs in linear regression models to predict VT1, VT2 and maximum loads. The errors of the predictions are similar to the load resolution.Postprint (published version

Asynchronous processing for latent fingerprint identification on heterogeneous CPU-GPU systems

Latent fingerprint identification is one of the most essential identification procedures in criminal investigations. Addressing this task is challenging as (i) it requires analyzing massive databases in reasonable periods and (ii) it is commonly solved by combining different methods with very complex data-dependencies, which make fully exploiting heterogeneous CPU-GPU systems very complex. Most efforts in this context focus on improving the accuracy of the approaches and neglect reducing the processing time. Indeed, the most accurate approach was designed for one single thread. This work introduces the fastest methodology for latent fingerprint identification maintaining high accuracy called Asynchronous processing for Latent Fingerprint Identification (ALFI). ALFI fully exploits all the resources of CPU-GPU systems using asynchronous processing and fine-coarse parallelism for analyzing massive databases. Our approach reduces idle times in processing and exploits the inherent parallelism of comparing latent fingerprints to fingerprint impressions. We analyzed the performance of ALFI on Linux and Windows operating systems using the well-known NIST/FVC databases. Experimental results reveal that ALFI is in average 22x faster than the state-of-the-art algorithm, reaching a value of 44.7x for the best-studied case

Vaccination programs, parity, and calving season as factors affecting the risk of fetal losses and mummified fetuses in Holstein cows

Aim of the study: To investigate vaccination programs, parity, and calving season as factors affecting the risk of abortion and mummified fetuses in Holstein cows.Area of study: Hot zone of Northeast Mexico.Material and methods: Multiple logistic regression models were used to examine the relationship between peripartum disorders, parity, previous occurrence of abortion, season of calving, vaccination program, incidence of abortion, and mummified fetuses in Holstein cows.Main results: For 7014 pregnancies (2886 cows), the percentage of cows aborting and having mummified fetuses was 17.7% and 1.1%, respectively. As the number of brucellosis vaccinations increased, the incidence of abortion increased (10.4% for a single vaccination and 38.0% for 6 accumulated vaccinations). Abortion for cows having 1-2 previous abortions (56%) and >2 abortions (77%) was fivefold and sevenfold greater (p<0.01), respectively, than that for cows without previous abortion. Other important risk factors for abortion were number of calvings (19.8% for nulliparous and primiparous vs. 13.8% for >3 parturitions; OR=1.7, p<0.01), leptospirosis vaccine application <55 days postpartum (dpp; OR=1.3, p<0.05), viral vaccine application >37 dpp (OR=1.3, p<0.01), brucellosis vaccine application >20 dpp (OR=1.6, p<0.01), and no application of clostridial vaccine (OR=3.7, p<0.01). Significant risk factors for mummified fetuses were application of ≥3 brucellosis vaccinations (OR=3.3, p<0.01), no application of 10-way clostridial vaccine (OR=2.3, p<0.01), >2 previous abortions (OR=18.4, p<0.01), and calving in autumn (OR=0.4, compared to winter, p<0.05).Research highlights: Risk of abortion and mummified fetuses in Holstein cows has been found to be related to vaccination programs