Partial least squares discriminant analysis: A dimensionality reduction method to classify hyperspectral data

The recent development of more sophisticated spectroscopic methods allows acquisition of high dimensional datasets from which valuable information may be extracted using multivariate statistical analyses, such as dimensionality reduction and automatic classification (supervised and unsupervised). In this work, a supervised classification through a partial least squares discriminant analysis (PLS-DA) is performed on the hy- perspectral data. The obtained results are compared with those obtained by the most commonly used classification approaches

Partial least squares discriminant analysis: A dimensionality reduction method to classify hyperspectral data

The recent development of more sophisticated spectroscopic methods allows acqui- sition of high dimensional datasets from which valuable information may be extracted using multivariate statistical analyses, such as dimensionality reduction and automatic classification (supervised and unsupervised). In this work, a supervised classification through a partial least squares discriminant analysis (PLS-DA) is performed on the hy- perspectral data. The obtained results are compared with those obtained by the most commonly used classification approaches

Application of nuclear magnectic resonance (NRM) to study of grape dehydration cv. bombino

[SPA] Actualmente Italia ha experimentado un importante crecimiento en la producción de vinos dulces o de postre de calidad. Asimismo, se han modificado las técnicas de secado de sistemas tradicionales a sistemas más tecnificados. El incremento de la demanda por una mejor calidad de los productos, ha provocado la investigación y desarrollo de técnicas de medida y evaluación no destructiva. La técnica de deshidratación consiste en un túnel de secado dotado de ventiladores que trabajan en régimen de aspiración donde se controlan las variables de velocidad de aire, temperatura y humedad relativa. Se seleccionaron 100 bayas numeradas y se dispusieron en el interior del túnel a una velocidad de aire de 1,5 m/s, una temperatura de 20ºC y una humedad relativa 45-50%. El tiempo de secado fue de 13 días hasta alcanzar aproximadamente el 30% de peso perdido. Se tomaron diferentes imágenes de resonancia magnética (RMI) a lo largo del proceso de secado, pudiendo visualizar el movimiento del agua durante el proceso de deshidratación, que ocurre desde las capas más superficiales hacia el centro geométrico de la baya. [ENG] Now days, Italy has experimented an important development in the production of quality sweet wines or dessert wines. In this way, it has modified the systems of drying techniques. The increase of the need of a better quality of products, has caused the research and the development of non destructive measurement and evaluation techniques. The dehydration technique consists of drying tunnel with funs working in a regime of aspiration where the air variation, temperature and relative humidity are controlled.100 berries numbered were selected and they were set into the tunnel at an air speed of 1,5 m/s, a temperature of 20ºC and the relative humidity 45-50%. The time of drying was 13 days until reaching 30% of weight loss. It takes different nuclear magnetic imagining during grape drying. We can observe the water movement during the dehydration process which happens from the superficial tissue below the skin towards to the centre by concentric circles.Trabajo de investigación financiado por el Ministerio de Agricultura Italiano (MUVON Project). Al programa Sócrates /Erasmus de la UPCT la ayuda financiera para la estancia de Alejandro Tomás en Italia

Innovative application of NIR-AOTF and MRI to study water behaviour in cut flower

In order to study the water status of cut flowers, a comparison study was made between flowers stored in water and flowers stored «dry pack», by using a portable NIR (near infrared)-AOTF(acousto-optical tunable filter) instrument and MRI (magnetic resonance imaging). As model flower, Zantedeschia aethiopica (commercially known as Calla lily) was used. To predict the weight loss and water content by NIR-AOTF, cut flowers were dried in a cold room at 10°C (±1°C) and 85% (±5%) relative humidity (RH), and measured for weight loss. For MRI application, 4 and 20°C storage temperatures were used for flowers kept in water or dry; two stem sections, basal and middle, were measured. Significant correlation results for weight loss and water content ( R2 in calibration = 0.98 for estimated % of water loss and 0.96 for % of water content; R2 cv = 0.95 and 0.90) were obtained by NIR-AOTF spectra acquisitions. MRI detected vessel degradation in the stem of the water-stored flowers at 4°C but at 20°C in dry storage no vessel degradation appeared and images were correlated with dry matter values. The use of image software allowed the transformation of images in normalized population and pixel intensity, which gave hints about the potential use of these data to combine with NIR-AOTF data. NIR-AOTF, an easy-to-use and non destructive instrument, can be used to predict the vase life of cut flowers by measuring water content or weight loss. MRI is a powerful tool to identify the plugging of vessels but it is destructive; the image software used represents a useful tool to correlate MRI with NIR-AOTF to predict vessel plugging

Nanoscale Simulation of Three-contact Graphene Ballistic Junctions

In this work, three-terminal ballistic junctions, made of three-branch graphene nanoribbons (GNRs), are considered and simulated at the nanometric scale. The analysis is carried out by a scattering matrix approach, in a discrete formulation optimized for GNR devices. The ballisticity and the scattering properties of the junction contribute to the nonlinear behaviour, as, in fact, a sinusoidal voltage between two GNR branches results in a non-sinusoidal current at the third branch. The input-output characteristic is hardly predictable at the nanoscale, as it depends on several cooperating factors, namely the potential distribution and the geometry of the junction. Several numerical examples are shown to illustrate the above concepts

Application of near infrared spectroscopy to study of grape dehydration cv. montepulciano

[SPA] Actualmente Italia ha experimentado un importante crecimiento en la producción de vinos dulces o de postre de elevada calidad. Asimismo, se han modificado las técnicas de secado de sistemas tradicionales a sistemas más tecnificados. El incremento de la demanda por una mejor calidad de estos vinos, ha provocado la investigación y desarrollo de técnicas de medida y evaluación no destructiva. La técnica de deshidratación consiste en un túnel de secado dotado de ventiladores que trabajan en régimen de aspiración donde se controlan las variables de velocidad de aire, temperatura y HR. Para el trabajo experimental, se seleccionaron 50 bayas numeradas y se dispusieron en el interior de un túnel de secado a una velocidad de aire de 1,5 m s-1 a una temperatura de 20ºC y HR del 45-50%. El tiempo de secado fue de 13 días hasta alcanzar aproximadamente el 30% de peso perdido. Diariamente se calculó la pérdida de peso y el espectro en el infrarrojo cercano (NIR) de cada baya. Los resultados de la espectroscopía NIR son reflejados como un espectro de absorbancia en la región infrarroja de longitud de onda, donde se pueden identificar los picos correspondientes a la absorbancia del agua (1400-1440 nm y 1900-1950 nm). La aplicación de la espectroscopía NIR al proceso de secado permite la observación de la variación del espectro en el tiempo así como la predicción de los tiempos de secado. [ENG] Nowadays, Italy has experimented an important development in the production of high quality sweet wines. In this way, the berry drying system has been modified to more sophisticated techniques . Consumer demands of better quality products, have induced the research and development of non destructive measurement and evaluation techniques. The dehydration system consists of a drying tunnel with funs working in an aspiration regime where the air variation, temperature and RH are controlled. Fifty numbered berries were selected and disposed into the tunnel at an air speed of 1,5 m s-1, temperature of 20ºC and RH of 45-50%. The drying time was 13 days until weight loss in berries reached 30%. Weight loss and NIR spectrum of each berry were dayly monitored. The spectroscopy results reports an absorbance spectrum in the infrared region, where it is possible to identify water absorbance (1400-1440 nm and 1900-1950 nm). The application of NIR spectroscopy for grape drying allowed the observation of the spectre variation and drying time prediction.Trabajo de investigación financiado por el Ministerio de Agricultura Italiano (MUVON Project). Al programa Sócrates /Erasmus de la UPCT la ayuda financiera para la estancia de Alejandro Tomás en Italia

Postharvest dehydration and defoliation

Background and Aims: Sfursat is an Italian wine produced with partially dehydrated Nebbiolo grapes in the Valtellina region which is located at high altitude. The research aims to understand the influence of fruit exposure on the rate of water loss by harvested fruit and the influence of exposure and dehydration on the content of phenolic substances and anthocyanins in the wine. Methods and Results: Clusters of Nebbiolo grapes from control vines (ND) and from vines that were defoliated at fruitset (DFS) or post-veraison (DPV) were harvested at a sugar concentration of about 230 g/L (there was no significant difference among the treatments), and dehydrated at 10, 20 or 30°C and at 60% relative humidity (RH), and air flow. Fruit were sampled at 10 and 20% weight loss (WL). Leaf removal had little effect on the physical characteristics of bunches and on the anthocyanins content and profile of harvested Nebbiolo grapes but affected dehydration. At 10 and 20°C, DFS fruit lost mass more slowly than DPV and ND fruit. In ND fruit, 20% WL reduced anthocyanins from 554 mg/kg fresh mass (FM) at harvest to 458, 432 and 396 mg/kg FM at 10, 20 and 30°C, respectively. In DFS and DPV berries, anthocyanins increased during dehydration at 10°C. At harvest, ND berries had a lower content of total stilbenes than those from defoliated vines. Dehydration (10°C, 20% WL) increased stilbene concentration in ND and DPV fruit. Dehydration at 10°C induced a rise in the flavonol concentration in fruit from defoliated vines. Catechin concentration was 106.5 mg/kg DM (dry mass), the highest value in ND berries at harvest. Wine was produced only from grapes dehydrated at 10°C. Wine from DFS fruit had a higher content of phenolic substances (2704.8 mg/L) and anthocyanins (104 mg/L) than that from DPV (2454.9 and 96.2 mg/L, respectively) and ND (2301.9 and 100.5 mg/L, respectively) fruit. Conclusions: Postharvest dehydration was slower where vines had been defoliated and resulted in changes in the ratios among groups of phenolic substances as well as among single phenolic components. Significance of the Study: In Nebbiolo grapes for Sfurzat wine production, defoliation at fruit set enables fruit to reach phenolic maturity at a lower sugar concentration allowing dehydration to increase sugar concentration without producing excessively alcoholic wines

Three-dimensional graphene on a nano-porous 4H-SiC backbone: a novel material for food sensing applications

Sensors which are sensitive to volatile organic compounds and thus able to monitor the conservation state of food, are precious because they work non-destructively and allow to avoid direct contact with the food, ensuring hygienic conditions. In particular, the monitoring of rancidity would solve a widespread issue in food storage. The sensor discussed here is produced utilizing a novel three-dimensional arrangement of graphene, which is grown on a crystalline silicon carbide (SiC) wafer previously porousified by chemical etching. This approach allows a very high surface-to.volume ratio. Furthermore, the structure of the sensor surface features a large amount of edges, dangling bounds, and active sites, which make the sensor, on a chemically robust skeleton, chemically active, particularly to hydrogenated molecules. The interaction of the sensor with such compounds is read out by measuring the sensor resistance in a four wire configuration. The sensor performance has been assessed on three hazelnut samples: sound hazelnuts, spoiled hazelnuts, and stink bug hazelnuts. A resistance variation of about DeltaR = 0.13 (0.02) Ohm between sound and damaged hazelnuts has been detected. Our measurements confirm the ability of the sensor to discriminate between sound and damaged hazelnuts. The sensor signal is stable for days, providing the possibility to use this sensor for the monitoring of the storage state of fats and foods in general.Comment: 11 pages, 6 figures 1 tabl

A Novel tDCS Sham Approach Based on Model-Driven Controlled Shunting

Abstract Background Transcranial direct current stimulation (tDCS), a non-invasive brain stimulation technique able to transiently modulate brain activity, is surging as one of the most promising therapeutic solutions in many neurological and psychiatric disorders. However, profound limitations exist in current placebo (sham) protocols that limit single- and double-blinding, especially in non-naive subjects. Objective /hypothesis: To ensure better blinding and strengthen reliability of tDCS studies and trials, we tested a new optimization algorithm aimed at creating an "active" sham tDCS condition (ActiSham hereafter) capable of inducing the same scalp sensations perceived during real stimulation, while preventing currents from reaching the cortex and cause changes in brain excitability. Methods A novel model-based multielectrode technique —optimizing the location and currents of a set of small electrodes placed on the scalp— was used to control the relative amount of current delivered transcranially in real and placebo multichannel tDCS conditions. The presence, intensity and localization of scalp sensations during tDCS was evaluated by means of a specifically designed questionnaire administered to the participants. We compared blinding ratings by directly addressing subjects' ability to discriminate across conditions for both traditional (Bifocal-tDCS and -Sham, using sponge electrodes) and our novel multifocal approach (both real Multifocal-tDCS and ActiSham). Changes in corticospinal excitability were monitored based on Motor Evoked Potentials (MEPs) recorded via concurrent Transcranial Magnetic Stimulation (TMS) and electromyography (EMG). Results Subjects perceived Multifocal-tDCS and ActiSham similarly in terms of both scalp sensations and their localization on the scalp, whereas traditional Bifocal stimulation was rated as more painful and annoying compared to its Sham counterpart. Additionally, differences in scalp localization were reported for active/sham Bifocal-tDCS. As for MEPs amplitude, a main effect of stimulation was found when comparing Bifocal-Sham and ActiSham (F(1,13)= 6.67, p=.023), with higher MEPs amplitudes after the application of Bifocal-Sham. Conclusions Compared to traditional Bifocal-tDCS, ActiSham offers better participants' blinding by inducing very similar scalp sensations to those of real Multifocal tDCS both in terms of intensity and localization, while not affecting corticospinal excitability