This paper presents a technique to derive the best offering strategy for a wind power producer in an electricity market that includes various trading floors. Uncertainty pertaining to wind ...availability, market prices at the different trading stages, and balancing energy needs are properly taken into account. Risk on profit variability is suitably controlled at the cost of a small reduction in expected profit. The proposed technique translates into a linear programming problem of moderate size, which is readily solvable using commercially available software. A variety of numerical case studies demonstrate the interest and effectiveness of the proposed technique. Appropriate conclusions are duly drawn.
This paper analyzes the behavior of Hong's point estimate methods to account for uncertainties on the probabilistic power flow problem. This uncertainty may arise from different sources as load ...demand or generation unit outages. Point estimate methods constitute a remarkable tool to handle stochastic power system problems because good results can be achieved by using the same routines as those corresponding to deterministic problems, while keeping low the computational burden. In previous works related to power systems, only the two-point estimate method has been considered. In this paper, four different Hong's point estimate schemes are presented and tested on the probabilistic power flow problem. Binomial and normal distributions are used to model input random variables. Results for two different case studies, based on the IEEE 14-bus and IEEE 118-bus test systems, respectively, are presented and compared against those obtained from the Monte Carlo simulation. Particularly, this paper shows that the use of the scheme provides the best performance when a high number of random variables, both continuous and discrete, are considered.
Mediterranean and low-fat diets are effective in the primary prevention of cardiovascular disease. We did a long-term randomised trial to compare the effects of these two diets in secondary ...prevention of cardiovascular disease.
The CORDIOPREV study was a single-centre, randomised clinical trial done at the Reina Sofia University Hospital in Córdoba, Spain. Patients with established coronary heart disease (aged 20–75 years) were randomly assigned in a 1:1 ratio by the Andalusian School of Public Health to receive a Mediterranean diet or a low-fat diet intervention, with a follow-up of 7 years. Clinical investigators (physicians, investigators, and clinical endpoint committee members) were masked to treatment assignment; participants were not. A team of dietitians did the dietary interventions. The primary outcome (assessed by intention to treat) was a composite of major cardiovascular events, including myocardial infarction, revascularisation, ischaemic stroke, peripheral artery disease, and cardiovascular death. This study is registered with ClinicalTrials.gov, NCT00924937.
From Oct 1, 2009, to Feb 28, 2012, a total of 1002 patients were enrolled, 500 (49·9%) in the low-fat diet group and 502 (50·1%) in the Mediterranean diet group. The mean age was 59·5 years (SD 8·7) and 827 (82·5%) of 1002 patients were men. The primary endpoint occurred in 198 participants: 87 in the Mediterranean diet group and 111 in the low-fat group (crude rate per 1000 person-years: 28·1 95% CI 27·9–28·3 in the Mediterranean diet group vs 37·7 37·5–37·9 in the low-fat group, log-rank p=0·039). Multivariable-adjusted hazard ratios (HRs) of the different models ranged from 0·719 (95% CI 0·541–0·957) to 0·753 (0·568–0·998) in favour of the Mediterranean diet. These effects were more evident in men, with primary endpoints occurring in 67 (16·2%) of 414 men in the Mediterranean diet group versus 94 (22·8%) of 413 men in the low-fat diet group (multiadjusted HR 0·669 95% CI 0·489–0·915, log-rank p=0·013), than in 175 women for whom no difference was found between groups.
In secondary prevention, the Mediterranean diet was superior to the low-fat diet in preventing major cardiovascular events. Our results are relevant to clinical practice, supporting the use of the Mediterranean diet in secondary prevention.
Fundacion Patrimonio Comunal Olivarero; Fundacion Centro para la Excelencia en Investigacion sobre Aceite de Oliva y Salud; local, regional, and national Spanish Governments; European Union.
This paper proposes a methodology to determine the required level of spinning and nonspinning reserves in a power system with a high penetration of wind power. The computation of the required reserve ...levels and their costs is achieved through a stochastic programming market-clearing model spanning a daily time horizon. This model considers the network constraints and takes into account the cost of both the load shedding and the wind spillage. The methodology proposed is illustrated using an example and a realistic case study. Some conclusions are finally drawn.
A stereolithography-based additive manufacturing technique has been used for the fabrication of advanced ceramics. A customised 3D printer using a Digital Light Processing (DLP) projector as UV ...source has been built to fabricate green bodies from photosensitive resins loaded with 25–60wt% of alumina, 3- and 8-YSZ. The 3D-printed bodies were then sintered in the 1200–1500°C and exhibited thermal stability. As expected, higher ceramic loadings rendered objects with higher density for a given sintering temperature. The limit of solid loading in the resin is approximately 60% and beyond those contents, the extra ceramic appears as powder loosely adhered to the sintered objects. Photogrammetry was used to evaluate the accuracy of the 3D printing process and highlighted a marked deviation between the CAD model and the resulting object, particularly in the top part of the specimens, possibly due to the use of volatile solvents which cause changes in the photoresins used. Nevertheless, that problem may be overcome by thermostatising the printer vat and/or using solvents with higher boiling point. The results obtained suggest the potential application of low cost DLP 3D printing techniques to process ceramics for a number of applications including ceramic fuel cells, piezoelectrics, dental applications, etc.
Se ha empleado una técnica de fabricación aditiva basada en la estereolitografía para la producción de cerámicas avanzadas. Se ha diseñado y construido una impresora 3D personalizada empleando como fuente de UV un proyector DLP para fabricar cuerpos verdes a partir de resinas fotosensibles cargadas con el 25-60% en peso de alúmina, 3-YSZ y 8-YSZ. Los cuerpos impresos mostraron estabilidad térmica tras los correspondientes tratamientos de sinterización entre 1.200 y 1.500°C. Como era de esperar, los mayores contenidos de sólido en las resinas dieron lugar a objetos con mayores densidades relativas para cada temperatura de sinterización. El límite de carga sólida en las resinas es aproximadamente un 60%, y por encima de estas cantidades, el contenido extra de cerámico aparece como partículas de polvo débilmente adheridas a los objetos sinterizados. Se empleó la fotogrametría para evaluar la precisión del proceso de impresión 3D donde se puso de manifiesto una marcada diferencia entre el modelo CAD y el objeto impreso, especialmente en la parte superior de los especímenes, posiblemente debido al uso de disolventes volátiles que provocan cambios en las fotorresinas empleadas. Sin embargo, este problema puede paliarse termostatizando el contenedor de la resina de la impresora y/o mediante el empleo de disolventes con mayor punto de ebullición. Los resultados obtenidos sugieren la potencial aplicación de técnicas de impresión 3D DLP de bajo coste para el procesado de cerámicos para aplicaciones como pilas de combustible cerámicas, piezoeléctricos, aplicaciones dentales, etc.
We conducted a large international study to estimate fractions of head and neck cancers (HNCs) attributable to human papillomavirus (HPV-AFs) using six HPV-related biomarkers of viral detection, ...transcription, and cellular transformation.
Formalin-fixed, paraffin-embedded cancer tissues of the oral cavity (OC), pharynx, and larynx were collected from pathology archives in 29 countries. All samples were subject to histopathological evaluation, DNA quality control, and HPV-DNA detection. Samples containing HPV-DNA were further subject to HPV E6*I mRNA detection and to p16(INK4a), pRb, p53, and Cyclin D1 immunohistochemistry. Final estimates of HPV-AFs were based on HPV-DNA, HPV E6*I mRNA, and/or p16(INK4a) results.
A total of 3680 samples yielded valid results: 1374 pharyngeal, 1264 OC, and 1042 laryngeal cancers. HPV-AF estimates based on positivity for HPV-DNA, and for either HPV E6*I mRNA or p16(INK4a), were 22.4%, 4.4%, and 3.5% for cancers of the oropharynx, OC, and larynx, respectively, and 18.5%, 3.0%, and 1.5% when requiring simultaneous positivity for all three markers. HPV16 was largely the most common type. Estimates of HPV-AF in the oropharynx were highest in South America, Central and Eastern Europe, and Northern Europe, and lowest in Southern Europe. Women showed higher HPV-AFs than men for cancers of the oropharynx in Europe and for the larynx in Central-South America.
HPV contribution to HNCs is substantial but highly heterogeneous by cancer site, region, and sex. This study, the largest exploring HPV attribution in HNCs, confirms the important role of HPVs in oropharyngeal cancer and drastically downplays the previously reported involvement of HPVs in the other HNCs.
Bacterial pathogens have evolved strategies that enable them to invade tissues and spread within the host. Enterococcus faecalis is a leading cause of local and disseminated multidrug-resistant ...hospital infections, but the molecular mechanisms used by this non-motile bacterium to penetrate surfaces and translocate through tissues remain largely unexplored. Here we present experimental evidence indicating that E. faecalis generates exopolysaccharides containing β-1,6-linked poly-N-acetylglucosamine (polyGlcNAc) as a mechanism to successfully penetrate semisolid surfaces and translocate through human epithelial cell monolayers. Genetic screening and molecular analyses of mutant strains identified glnA, rpiA and epaX as genes critically required for optimal E. faecalis penetration and translocation. Mechanistically, GlnA and RpiA cooperated to generate uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) that was utilized by EpaX to synthesize polyGlcNAc-containing polymers. Notably, exogenous supplementation with polymeric N-acetylglucosamine (PNAG) restored surface penetration by E. faecalis mutants devoid of EpaX. Our study uncovers an unexpected mechanism whereby the RpiA-GlnA-EpaX metabolic axis enables production of polyGlcNAc-containing polysaccharides that endow E. faecalis with the ability to penetrate surfaces. Hence, targeting carbohydrate metabolism or inhibiting biosynthesis of polyGlcNAc-containing exopolymers may represent a new strategy to more effectively confront enterococcal infections in the clinic.
This paper analyzes the impact of wind production on the locational marginal prices of a fully competitive pool-based electricity market. Wind productions are modeled as negative loads and ...characterized by historical data records. The analysis pertains to the structural relationship between wind production and locational marginal prices, and disregards the collateral effect of strategic offering. The study presented allows a statistical characterization of locational marginal prices as a function of the statistical data of the wind plants and the structure of the considered electric energy system.
Calcium carbonate precipitation at different values of the nominal ionic activity product (IAP) is studied in nanoliter and picoliter droplets at (20 ± 2 °C). Experiments are carried out through ...direct mixing of equimolar reactant solutions using two different setups: first, droplet-based microfluidics using Teflon capillaries (nanoliter experiments) and second, the microinjection technique under oil (picoliter droplets). Instantaneous precipitation of a metastable CaCO3 phase is initially observed. This phase is stabilized in time by reducing the initial volume of the experiments from the nano- to picoliters range and when the CaCl2/Na2CO3 ratio approaches 1. Further analysis by X-ray diffraction, transmission electron microscopy, and selected area electron diffraction confirms the first nucleated phase is CaCO3·6H2O (ikaite) and in few droplets ikaite plus CaCO3·H2O (monohydrocalcite). No evidence of amorphous calcium carbonate (ACC) is found even in conditions where the IAP exceeds the solubility product of this phase. The in vitro finding of ikaite formation and stabilization due to volume confinement is an unexpected result since it is the first time that this hydrous phase is stabilized at room temperature (it is normally found at near 0 °C) in the absence of additives. This result can be of interest for those biomineralization processes occurring in the confined volumes of intracellular vesicles and for biomimetic materials science in general.
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