Multiband photometric transit observations (spectro-photometric) have been used mostly so far to retrieve broadband transmission spectra of transiting exoplanets in order to study their atmospheres. ...An alternative method was proposed, and has only been used once, to recover broadband transmission spectra using chromatic Rossiter–McLaughlin observations. We use the chromatic Rossiter–McLaughlin technique on archival and new observational data obtained with the HARPS and CARMENES instruments to retrieve transmission spectra of HD 189733b. The combined results cover the widest retrieved broadband transmission spectrum of an exoplanet obtained from ground-based observation. Our retrieved spectrum in the visible wavelength range shows the signature of a hazy atmosphere, and also includes an indication for the presence of sodium and potassium. These findings all agree with previous studies. The combined visible and near-infrared transmission spectrum exhibits a strong steep slope that may have several origins, such as a super-Rayleigh slope in the atmosphere of HD 189733b, an unknown systematic instrumental offset between the visible and near-infrared, or a strong stellar activity contamination. The host star is indeed known to be very active and might easily generate spurious features in the retrieved transmission spectra. Using our CARMENES observations, we assessed this scenario and place an informative constraint on some properties of the active regions of HD 189733. We demonstrate that the presence of starspots on HD 189733 can easily explain our observed strong slope in the broadband transmission spectrum.
•A rapid analytical technique and a low-cost technology for olive oil quality control is proposed.•Oxidised compounds of virgin olive oil gave a specific fluorescence bands over ...400–460nm.•Calibration models for main quality parameters were construct using external validation method.•Determining quality parameters with a simple measure of a single fluorescence excitation wavelength.•The fluorescence characteristics of oils are used to authenticate and monitoring oils quality.
The fluorescence spectra of some olive oils were examined in their natural and oxidised state, with wavelength range emissions of 300–800nm and 300–400nm used as excitation radiation. The fluorescence emissions were measured and an assessment was made of the relationship between them and the main quality parameters of olive oils, such as peroxide value, K232, K270 and acidity. These quality parameters (peroxide value, K232, K270 and acidity) are determined by laboratory methods, which though not too sophisticated, they are required solvents and materials as well as time consuming and sample preparation; there is a need for rapid analytical techniques and a low-cost technology for olive oil quality control. The oxidised oils studied had a strong fluorescence band at 430–450nm. Extra virgin olive oil gave a different but interesting fluorescence spectrum, composed of three bands: one low intensity doublet at 440 and 455nm; one strong band at 525nm; and one of medium intensity at 681nm. The band at 681nm was identified as the chlorophyll band. The band at 525nm was derived, at least partially, from vitamin E.
The results presented demonstrate the ability of the fluorescence technique, combined with multivariate analysis, to characterise olive oils on the basis of all the quality parameters studied. Prediction models were obtained using various methods, such as partial least squares (PLS), N-way PLS (N-PLS) and external validation, in order to obtain an overall evaluation of oil quality.
The best results were obtained for predicting K270 with a root mean square (RMS) prediction error of 0.08 and a correlation coefficient obtained with the external validation of 0.924. Fluorescence spectroscopy facilitates the detection of virgin olive oils obtained from defective or poorly maintained fruits (high acidity), fruits that are highly degraded in the early stages (with a high peroxide value) and oils in advanced stages of oxidation, with secondary oxidation compounds (high K232 and K270). The results indicate the potential of a spectrofluorimetric method combined with multivariate analysis to differentiate, and even quantify, the levels of oil quality. The proposed methodology could be used to accelerate analysis, is inexpensive and allows a comprehensive assessment to be made of olive oil quality.
One of the most powerful methods used to estimate sky-projected spin-orbit angles of exoplanetary systems is through a spectroscopic transit observation known as the RossiterMcLaughlin (RM) effect. ...So far mostly single RM observations have been used to estimate the spin-orbit angle, and thus there have been no studies regarding the variation of estimated spin-orbit angle from transit to transit. Stellar activity can alter the shape of photometric transit light curves and in a similar way they can deform the RM signal. In this paper we present several RM observations, obtained using the HARPS spectrograph, of known transiting planets that all transit extremely active stars, and by analyzing them individually we assess the variation in the estimated spin-orbit angle. Our results reveal that the estimated spin-orbit angle can vary significantly (up to ~42°) from transit to transit, due to variation in the configuration of stellar active regions over different nights. This finding is almost two times larger than the expected variation predicted from simulations. We could not identify any meaningful correlation between the variation of estimated spin-orbit angles and the stellar magnetic activity indicators. We also investigated two possible approaches to mitigate the stellar activity influence on RM observations. The first strategy was based on obtaining several RM observations and folding them to reduce the stellar activity noise. Our results demonstrated that this is a feasible and robust way to overcome this issue. The second approach is based on acquiring simultaneous high-precision short-cadence photometric transit light curves using TRAPPIST/SPECULOOS telescopes, which provide more information about the stellar active region’s properties and allow a better RM modeling.
Abstract
We present C and O abundances in the Magellanic Clouds derived from deep spectra of H ii regions. The data have been taken with the Ultraviolet-Visual Echelle Spectrograph at the 8.2-m Very ...Large Telescope. The sample comprises five H ii regions in the Large Magellanic Cloud (LMC) and four in the Small Magellanic Cloud (SMC). We measure pure recombination lines (RLs) of C ii and O ii in all the objects, permitting to derive the abundance discrepancy factors (ADFs) for O2+, as well as their O/H, C/H and C/O ratios. We compare the ADFs with those of other H ii regions in different galaxies. The results suggest a possible metallicity dependence of the ADF for the low-metallicity objects; but more uncertain for high-metallicity objects. We compare nebular and B-type stellar abundances and we find that the stellar abundances agree better with the nebular ones derived from collisionally excited lines (CELs). Comparing these results with other galaxies we observe that stellar abundances seem to agree better with the nebular ones derived from CELs in low-metallicity environments and from RLs in high-metallicity environments. The C/H, O/H and C/O ratios show almost flat radial gradients, in contrast with the spiral galaxies where such gradients are negative. We explore the chemical evolution analysing C/O versus O/H and comparing with the results of H ii regions in other galaxies. The LMC seems to show a similar chemical evolution to the external zones of small spiral galaxies and the SMC behaves as a typical star-forming dwarf galaxy.
In this work, the maturity index of different samples of olives was objectively assessed by image analysis obtained through machine vision, in which algorithms of color-based segmentation and ...operators to detect edges were used. This method allows a fast, automatic and objective prediction of olive maturity index. This prediction value was compared to maturity index (MI), generally used by olive oil industry, based on the subjective visual determination of color of fruit skin and flesh. Machine vision was also applied to the automatic estimation of size and weight of olive fruits. The proposed system was tested to obtain a good performance in the classification of the fruit in batches. When applied to several olive samples, the maturity index predicted by machine vision was in close agreement with the maturity index of fruits visually estimated, values that are currently used as standards. The evaluation of weight of fruit also provided good results (R
2
= 0.91). These results obtained by image analysis can be used as a useful method for the classification of olives at the reception in olive mill, allowing a better quality control of the production process.
External quality is an important factor in the extraction of olive oil and the marketing of olive fruits. The appearance and presence of external damage are factors that influence the quality of the ...oil extracted and the perception of consumers, determining the level of acceptance prior to purchase in the case of table olives. The aim of this paper is to report on artificial vision techniques developed for the online estimation of olive quality and to assess the effectiveness of these techniques in evaluating quality based on detecting external defects. This method of classifying olives according to the presence of defects is based on an infrared (IR) vision system. Images of defects were acquired using a digital monochrome camera with band-pass filters on near-infrared (NIR). The original images were processed using segmentation algorithms, edge detection and pixel value intensity to classify the whole fruit. The detection of the defect involved a pixel classification procedure based on nonparametric models of the healthy and defective areas of olives. Classification tests were performed on olives to assess the effectiveness of the proposed method.
This research showed that the IR vision system is a useful technology for the automatic assessment of olives that has the potential for use in offline inspection and for online sorting for defects and the presence of surface damage, easily distinguishing those that do not meet minimum quality requirements.
•We use digital infrared images to detect the presence of damages in olive fruits.•The spectral images provide a good contrast between defective and healthy tissue of fruits.•Using images segmentation by algorithms based on the edge-detection and connected components.•We report a system to classifying olives according to the presence of defects.
The aim of this study was to evaluate the potential of low-resolution Raman spectroscopy for monitoring the oxidation status of olive oil. Primary and secondary oxidation parameters such as peroxide ...value, K232 and K270 were studied. Low-resolution Raman spectra ranging from 200 to 2700 cm−1 in a set of 126 oxidized and virgin olive oil samples were collected directly using a probe. Partial Least Squares was used to calibrate the Raman instrument for the different targeted parameters. The performance of the models was determined by using validation sets, and the best results obtained were: R2 = 0.91, RMSEP = 2.57 for the peroxide value content; R2 = 0.88, RMSEP = 0.37 for K232; and R2 = 0.90, RMSEP = 0.08 for K270. These results demonstrated that low-resolution Raman spectroscopy could be a relevant technique for evaluating the oxidation status of olive oils because the key oxidation parameters can be determined quickly and in a non-destructive and direct way.
► In this study, the aim was to evaluate the potential of low-resolution Raman spectroscopy for monitoring the oxidation status of olive oil. ► Primary and secondary oxidation parameters such as peroxide value, K232 and K270 were studied. ► The results obtained with the constructed PLS models correlated well with those obtained in the laboratory. ► The models had an RPD value lower than 5, which can be considered acceptable for screening and for generate ranking data. ► The use of portable Raman spectroscopy, combined with some chemometric tools for analyzing the oxidative state of olive oil.
► The work described here aims to determine the potential of low-resolution Raman spectroscopy for the discrimination of olives before the oil processing stage in order to discriminate healthy and ...diseased olives. ► Low-resolution Raman spectroscopy was applied together with multivariate procedures to achieve this aim. ► Supervised classification methods were then applied. ► The best results were obtained using the KNN method, with prediction abilities of 100% for ‘sound’ and 97% for ‘ground’ in an independent validation set.
In the real marketplace, providing high-quality olive oil is important from the perspective of both consumers and producers. Quality control should meet all requirements in the production process, from farm to packaging. The quality of olive oil can be affected by several factors, including agricultural techniques, seasonal conditions, farming systems, maturity, method and duration of storage, and process technology.
The quality of oil produced also depends largely on the quality of the olives. In an enterprise aimed at producing high-quality oils, olives with defects (‘ground’; i.e., fallen to the ground) should be separated from healthy fruit (‘sound’; i.e., collected directly from the tree), because a very small portion of low-quality fruit can ruin the whole batch.
The fruit falls partly because of its maturation process, but also because of pest and disease attack or weather conditions (strong wind). Fruit that has fallen to the ground can suffer a rapid deterioration in quality.
Currently, the separation of fruits is based mainly on visual inspection or information provided by the farmer. These are not very reliable procedures. Methods using analytical parameters to characterize the oil, such as acidity and peroxide value, can be applied, but they require a lot of time and materials. Alternative techniques are therefore needed for the rapid and inexpensive discrimination of olives as part of a quality control strategy.
The work described here aims to determine the potential of low-resolution Raman spectroscopy for the discrimination of olives before the oil processing stage in order to detect whether they have been collected directly from the tree (i.e., healthy fruit) or not. Low-resolution Raman spectroscopy was applied together with multivariate procedures to achieve this aim. PCA was used to find natural clusters in the data. Supervised classification methods were then applied: Soft Independent Modeling of Class Analogy (SIMCA), PLS Discriminate Analysis (PLS-DA) and K-nearest neighbors (KNN). The best results were obtained using the KNN method, with prediction abilities of 100% for ‘sound’ and 97% for ‘ground’ in an independent validation set.
These results demonstrated the potential of a portable Raman instrument for detecting good quality olives before the oil processing stage, by developing models that could be applied before this stage, thus contributing to an overall improvement in quality control.
La fotorreportería del conflicto armado en Colombia entre 2002-2006 constituye una investigación concomitante al desarrollo de un proyecto de tesis doctoral. Este artículo se circunscribe a la ...metodología de esa primera investigación preliminar en cuanto base de una fuente primaria y estudio de esa fotorreportería del rotativo El Tiempo de Bogotá. De ahí que el volumen de ese archivo constituya hoy un repositorio visual del conflicto armado en Colombia de estimado valor para el Centro de Documentación en Imagen y Diseño de la Universidad de Caldas, Manizales, Colombia.
The atmospheres of sub-Neptunes are expected to exhibit considerable chemical diversity, beyond what is anticipated for gas-giant exoplanets. In the current study, we construct self-consistent ...radiative transfer and equilibrium chemistry models to explore this chemical diversity. We use GJ 436 b as a case study to further study joint atmosphere-interior models. In particular, we constrain the properties of the interior and atmosphere of the planet based on the available Spitzer measurements. While it is possible to fit the emission spectrum of GJ 436 b using a high-metallicity model, we demonstrate that such an atmosphere is inconsistent with physically plausible interior structures. It remains the case that no existing study can adequately fit the 4.5-micron Spitzer secondary eclipse measurement, which is probably caused by chemical disequilibrium. Finally, an information content analysis reveals that emission and transmission spectra constrain the carbon-to-oxygen ratio and metallicity at different wavelengths, but the former are less susceptible to flat spectra stemming from highly metal-enriched atmospheres. With the recently-launched JWST, we recommend that future analysis of emission and transmission spectra of sub-Neptune planets are carried out self-consistently using both the atmospheric and interior structure models.
PDF
