Solar forecasting provides valuable information for grid management. Satellite-based forecasting tools account for the short-term intra-day time horizons, typically outperforming numerical weather ...predictions up to 4–5 h ahead. The method consist of three separated stages, namely, cloud motion estimation, motion extrapolation and satellite-to-irradiation conversion. In this work we compare different satellite-based proposals for hourly irradiation forecast up to 5 h ahead using a 2-years data set. The widely-used Lorenz’s block matching technique and four optical flow (OF) algorithms are assessed, both at image and irradiation levels. All the methods are locally optimized to obtain their peak performance. It is found that the OF algorithm which combines an L1 data penalty term on the optical flow equation with total variation regularization (TVL1) outperforms the rest. Different image extrapolation approaches and spatial smoothing are also tested. It is found that changing the extrapolation technique does not have much impact in the overall performance and that important gains can be obtained by optimally smoothing the predicted images previous to solar irradiation conversion. By doing this, all methods outperform the exigent convex persistence benchmark, achieving positive forecasting skills. The tests are performed using GOES-East satellite images of south-east South America, and the methods’ optimal parameters are given.
•Five satellite Cloud Motion Vector solar irradiance forecasting methods are compared.•Methods are evaluated for cloudiness and global solar prediction up to 5 h ahead.•The TVL1 optical flow method outstands as the best option.•All methods’ parameters are adjusted for an intermediate solar variability region.•The value of spatial smoothing and different extrapolation techniques are analyzed.
We have observed several relatively deep transits of the white dwarf WD 1145+017 with the Gran Telescopio Canarias (GTC) in the wavelength range 480 to 920 nm. The observations covered approximately ...one hour on 2016 January 18 and two hours on 2016 January 20. There was variable extinction of the white dwarf during much of that time, but this extinction was punctuated by four sharp transits with depths ranging from 25% to 40%. The spectrum was dispersed with a grism and the flux data were ultimately summed into four bands centered at 0.53, 0.62, 0.71, and 0.84 μm. After careful normalization, we find that the flux light curves in all four bands are consistently the same, including through the deepest dips. We use these results to compute Ångström exponents, α, for the particles responsible for the extinction and find |⟨ α ⟩| ≲ 0.06, assuming that the extinction is relatively optically thin. We use the complex indices of refraction for common minerals to set constraints on the median sizes of possible dust grains and find that particle sizes ≲0.5 μm can be excluded for most common minerals.
•10 diffuse fraction models are evaluated against data from temperate climate in southern latitudes.•Most original models tend to overestimate diffuse irradiation.•Unbiased versions adjusted to the ...local data, are evaluated using cross-validation.•Multiple-predictor models perform best, with typical uncertainties close to 18%.
Knowledge of diffuse solar radiation is required for the estimation of global irradiation on inclined surfaces or for estimating DNI for CSP applications. Since diffuse irradiance data is comparatively scarce relative to global horizontal irradiance (GHI) data, several methods are used to estimate the diffuse component of GHI. These methods have a local component and most of them have been developed using data recorded in the northern hemisphere, where long-term reliable measurements of diffuse irradiance are available. This work considers ten models for hourly diffuse irradiation and evaluates their performance, both in their original and locally adjusted versions, against data recorded at five sites from a subtropical-temperate zone in the southern part of South America (latitudes between 30°S and 35°S). The raw data has been quality-assessed by using a set of seven sequential filters which preserve the natural spread of the data while removing unphysical data points. The local adjustment and performance evaluation are done using random-sampling cross-validation techniques on an ensemble. The best estimates result from locally adjusted multiple-predictor models, some of which can estimate hourly diffuse fraction with uncertainty of 18% of the mean.
A rotational study of the AlaAla dipeptide León, I; Alonso, E. R; Mata, S ...
Physical chemistry chemical physics : PCCP,
07/2020, Letnik:
22, Številka:
25
Journal Article
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Herein, we present the first rotational study of the AlaAla dipeptide, brought into the gas phase by laser ablation. Two different structures have been unveiled in the isolated environment of a ...supersonic expansion by Fourier transform microwave spectroscopy. These structures have been identified through their rotational and
14
N quadrupole coupling constants. The flexibility of the -NH
2
and -COOH ends allows the formation of strong intramolecular interactions giving rise to five- and seven-membered ring configurations.
Herein, we present the first rotational study of the AlaAla dipeptide, brought into the gas phase by laser ablation.
The Gulf of California (GC) is a unique large marine ecosystem characterized by its rich biodiversity, high biological productivity and endemism of marine life, which are the basis of Mexico's most ...important fisheries. However, as many other large ecosystems worldwide, it is subject to diverse anthropogenic pressures (overfishing, losses of biodiversity and habitats, pollution, climate variability and climate change (CC)). We reviewed over 180 studies dealing with the impacts of CC and climate variability in the GC region. Main issues on the impact of ENSO events, acidification, sea level rise, and water availability are discussed for the GC in a global context. Impacts of ENSO events on the GC are geographically heterogeneous, upwelling tends to be suppressed, and this in turn influences the distribution and abundance of marine mammals, fishes, shrimps, benthic species, seaweeds and phytoplankton. ENSO events strongly impact small pelagic fishes, key components of the GC ecosystem, thus affecting fisheries in general as well as non-harvested species such as marine mammals and sea birds. Probably the most well-known phenomenon associated to ENSO impact in the GC is coral bleaching, a process by which corals expel most of their microalgal endosymbionts to become pale or white (bleached). Beside shifts in the distributional limits of benthic organisms, invasions of alien species are also occuring. Harmful algal blooms (HABs) are common and recurrent in the GC. Fourteen HAB-forming species have been recorded, with Gymnodinium catenatum being the most frequent. HABs are inhibited by El Niño and promoted by La Niña. During El Niño events the size and biomass of macroalgal blooms tend to decrease. Finally, several aspects that require further research are proposed.
Context. The TESS and PLATO missions are expected to find vast numbers of new transiting planet candidates. However, only a fraction of these candidates will be legitimate planets, and the candidate ...validation will require a significant amount of follow-up resources. Radial velocity (RV) follow-up study can be carried out only for the most promising candidates around bright, slowly rotating, stars. Thus, before devoting RV resources to candidates, they need to be vetted using cheaper methods, and, in the cases for which an RV confirmation is not feasible, the candidate’s true nature needs to be determined based on these alternative methods alone. Aims. We study the applicability of multicolour transit photometry in the validation of transiting planet candidates when the candidate signal arises from a real astrophysical source (transiting planet, eclipsing binary, etc.), and not from an instrumental artefact. Particularly, we aim to answer how securely we can estimate the true uncontaminated star-planet radius ratio when the light curve may contain contamination from unresolved light sources inside the photometry aperture when combining multicolour transit observations with a physics-based contamination model in a Bayesian parameter estimation setting. More generally, we study how the contamination level, colour differences between the planet host and contaminant stars, transit signal-to-noise ratio, and available prior information affect the contamination and true radius ratio estimates. Methods. The study is based on simulations and ground-based multicolour transit observations. The contamination analyses were carried out with a contamination model integrated into the PYTRANSIT v2 transit modelling package, and the observations were carried out with the MuSCAT2 multicolour imager installed in the 1.5 m Telescopio Carlos Sanchez in the Teide Observatory, in Tenerife. Results. We show that multicolour transit photometry can be used to estimate the amount of flux contamination and the true radius ratio. Combining the true radius ratio with an estimate for the stellar radius yields the true absolute radius of the transiting object, which is a valuable quantity in statistical candidate validation, and enough in itself to validate a candidate whose radius falls below the theoretical lower limit for a brown dwarf.
In this work, three models are built to produce intra-day probabilistic solar forecasts with lead times ranging from 10 min to 3 h with a granularity of 10 min. The first model makes only use of past ...ground measurements. The second model upgrades the first one by adding a variability metric obtained also from the past ground measurements. The third model takes as additional input the satellite albedo. A non parametric approach based on the linear quantile regression technique is used to generate the set of quantiles that summarize the predictive distributions of the global solar irradiance at a horizontal plane (GHI). The probabilistic models are evaluated on several sites that experience very different climatic conditions. It is shown that incorporating variability significantly reduces the width of interval predictions. The addition of satellite information further improves the quality of the probabilistic forecasts.
•Short-term variability and satellite albedo are tested for probabilistic forecast.•The models that include the extra variables outperform the baseline lagged model.•Adding variability improves the forecast in low/intermediate solar variability sites.•At intermediate variability sites, satellite improves CDF accuracy and average width.•Variability improves the forecast under clear sky while satellite under cloudy skies.
Evidence-informed strategic planning is a top priority in Mental Health (MH) due to the burden associated with this group of disorders and its societal costs. However, MH systems are highly complex, ...and decision support tools should follow a systems thinking approach that incorporates expert knowledge. The aim of this paper is to introduce a new Decision Support System (DSS) to improve knowledge on the health ecosystem, resource allocation and management in regional MH planning. The Efficient Decision Support-Mental Health (EDeS-MH) is a DSS that integrates an operational model to assess the Relative Technical Efficiency (RTE) of small health areas, a Monte-Carlo simulation engine (that carries out the Monte-Carlo simulation technique), a fuzzy inference engine prototype and basic statistics as well as system stability and entropy indicators. The stability indicator assesses the sensitivity of the model results due to data variations (derived from structural changes). The entropy indicator assesses the inner uncertainty of the results. RTE is multidimensional, that is, it was evaluated by using 15 variable combinations called scenarios. Each scenario, designed by experts in MH planning, has its own meaning based on different types of care. Three management interventions on the MH system in Bizkaia were analysed using key performance indicators of the service availability, placement capacity in day care, health care workforce capacity, and resource utilisation data of hospital and community care. The potential impact of these interventions has been assessed at both local and system levels. The system reacts positively to the proposals by a slight increase in its efficiency and stability (and its corresponding decrease in the entropy). However, depending on the analysed scenario, RTE, stability and entropy statistics can have a positive, neutral or negative behaviour. Using this information, decision makers can design new specific interventions/policies. EDeS-MH has been tested and face-validated in a real management situation in the Bizkaia MH system.
Pheochromocytomas (PCCs) and paragangliomas (PGLs) are chromaffin-cell tumors that arise from the adrenal medulla and extra-adrenal paraganglia, respectively. The dysfunction of genes involved in the ...cellular response to hypoxia, such as VHL, EGL nine homolog 1, and the succinate dehydrogenase (SDH) genes, leads to a direct abrogation of hypoxia inducible factor (HIF) degradation, resulting in a pseudo-hypoxic state implicated in PCC/PGL development. Recently, somatic post-zygotic mutations in EPAS1 (HIF2A) have been found in patients with multiple PGLs and congenital erythrocytosis. We assessed 41 PCCs/PGLs for mutations in EPAS1 and herein describe the clinical, molecular and genetic characteristics of the 7 patients found to carry somatic EPAS1 mutations; 4 presented with multiple PGLs (3 of them also had congenital erythrocytosis), whereas 3 were single sporadic PCC/PGL cases. Gene expression analysis of EPAS1-mutated tumors revealed similar mRNA EPAS1 levels to those found in SDH-gene- and VHL-mutated cases and a significant up-regulation of two hypoxia-induced genes (PCSK6 and GNA14). Interestingly, single nucleotide polymorphism array analysis revealed an exclusive gain of chromosome 2p in three EPAS1-mutated tumors. Furthermore, multiplex-PCR screening for small rearrangements detected a specific EPAS1 gain in another EPAS1-mutated tumor and in three non-EPAS1-mutated cases. The finding that EPAS1 is involved in the sporadic presentation of the disease not only increases the percentage of PCCs/PGLs with known driver mutations, but also highlights the relevance of studying other hypoxia-related genes in apparently sporadic tumors. Finally, the detection of a specific copy number alteration affecting chromosome 2p in EPAS1-mutated tumors may guide the genetic diagnosis of patients with this disease.
WD 1145+017 was observed from 2015 November to 2016 July, for the purpose of characterizing transit behaviour of the white dwarf by dust clouds thought to be produced by fragments of an asteroid in ...close orbit with the star. Fortuitously, most of these observations were carried out during a time when the overall 'dip' activity was dramatically enhanced over that during its discovery with Kepler K2. By the end of our reported observations, the dip activity had declined to a level close to its K2 discovery state. Three notable events were observed. In 2016 January, a large number of dust clouds appeared that had an orbital period of 4.4912 h, and this event also marked the end of a three-month interval dominated by the K2 'A' period. The second event was a 2016 April 21 appearance of four dip features with drift lines in a waterfall (date versus phase) diagram that diverged from their origin date, at a location away from the 'A' asteroid, and which lasted for two weeks. The third event was the sudden appearance of a dip feature with a period of 4.6064 h, which is essentially the same as the K2 'B' period. The evolution of dip shape, depth, and total fade amount provide constraints on dust production and loss mechanisms. Collisions can account for the sudden appearance of dust clouds, and the sudden increase in dust amount, but another mechanism for continual dust production is also required.
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