Short-term post-harvest stress that affects profiles of volatile organic compounds and gene expression in rocket salad during early post-harvest senescence

Once harvested, leaves undergo a process of senescence which shares some features with developmental senescence. These include changes in gene expression, metabolites, and loss of photosynthetic capacity. Of particular interest in fresh produce are changes in nutrient content and the aroma, which is dependent on the profile of volatile organic compounds (VOCs). Leafy salads are subjected to multiple stresses during and shortly after harvest, including mechanical damage, storage or transport under different temperature regimes, and low light. These are thought to impact on later shelf life performance by altering the progress of post-harvest senescence. Short term stresses in the first 24 h after harvest were simulated in wild rocket (Diplotaxis tenuifolia). These included dark (ambient temperature), dark and wounding (ambient temperature), and storage at 4 \ub0C in darkness. The effects of stresses were monitored immediately afterwards and after one week of storage at 10 \ub0C. Expression changes in two NAC transcription factors (orthologues of ANAC059 and ANAC019), and a gene involved in isothiocyanate production (thiocyanate methyltransferase, TMT) were evident immediately after stress treatments with some expression changes persisting following storage. Vitamin C loss and microbial growth on leaves were also affected by stress treatments. VOC profiles were differentially affected by stress treatments and the storage period. Overall, short term post-harvest stresses affected multiple aspects of rocket leaf senescence during chilled storage even after a week. However, different stress combinations elicited different responses

Short-Term Post-Harvest Stress that Affects Profiles of Volatile Organic Compounds and Gene Expression in Rocket Salad During Early Post-Harvest Senescence

Once harvested, leaves undergo a process of senescence which shares some features with developmental senescence. These include changes in gene expression, metabolites, and loss of photosynthetic capacity. Of particular interest in fresh produce are changes in nutrient content and the aroma, which is dependent on the profile of volatile organic compounds (VOCs). Leafy salads are subjected to multiple stresses during and shortly after harvest, including mechanical damage, storage or transport under different temperature regimes, and low light. These are thought to impact on later shelf life performance by altering the progress of post-harvest senescence. Short term stresses in the first 24 h after harvest were simulated in wild rocket (Diplotaxis tenuifolia). These included dark (ambient temperature), dark and wounding (ambient temperature), and storage at 4 °C in darkness. The effects of stresses were monitored immediately afterwards and after one week of storage at 10 °C. Expression changes in two NAC transcription factors (orthologues of ANAC059 and ANAC019), and a gene involved in isothiocyanate production (thiocyanate methyltransferase, TMT) were evident immediately after stress treatments with some expression changes persisting following storage. Vitamin C loss and microbial growth on leaves were also affected by stress treatments. VOC profiles were differentially affected by stress treatments and the storage period. Overall, short term post-harvest stresses affected multiple aspects of rocket leaf senescence during chilled storage even after a week. However, different stress combinations elicited different responses

Hyperspectral remote sensing of coral reefs by semi-analytical model inversion – Comparison of different inversion setups

International audienceDue to its high spectral and spatial resolutions, airborne hyperspectral imaging has great potential for becoming a powerful large-scale monitoring tool for coral reef communities. In recent years, methods based on radiative transfer model inversion have shown promising results for extracting information about seabed type, bottom depth and water constituents from hyperspectral imagery. However, low signal-to-noise ratios (SNR) due to low water-leaving radiance combined with environmental variability make it very difficult to design an optimal processing algorithm. Here, we selected a state-of-the-art, forward semi-analytical model in which we included a mixing model of four seabed albedo, namely sand, corals, algae and seagrass. The purpose of this paper was then to compare different setups of the inversion scheme, each one having its own theoretical strengths and weaknesses regarding the different confounding factors. Six inversion setups were implemented, corresponding to the combinations between (i) three cost functions: least square (LS), spectral angle mapper (SAM) and least square on spectral derivative (LSD), and (ii) two physical constraints imposed on the seabed type retrieval: abundance sum-to-one constraint (ASC) and a relaxed version (RASC). Performances of bathymetry and seabed type retrieval were evaluated on hyperspectral data acquired in a coral reef environment in Réunion Island. Our results showed that the accuracy and robustness of the bathymetric estimation were greatly influenced by the choice of the inversion setup. RASC-LSD produced the overall best performances even if SAM-based inversion setups showed particularly low error dispersion with respect to Lidar derived bathymetry. RASC-LSD also produced the most accurate results in terms of spatial coverage of benthic components on a very shallow area (inner part of a fringing reef). The results on our study areas clearly highlighted the interest of relaxing the ASC when the bottom depth is shallow. In deeper areas, ASC versions of LS- and LSD-based inversion setups produced the best seabed type mapping results. Only broad seabed types could be retrieved in areas deeper than 10 m. © 2017 Elsevier Inc

Hyperspectral remote sensing of coral reefs by semi-analytical model inversion – Comparison of different inversion setups

International audienceDue to its high spectral and spatial resolutions, airborne hyperspectral imaging has great potential for becoming a powerful large-scale monitoring tool for coral reef communities. In recent years, methods based on radiative transfer model inversion have shown promising results for extracting information about seabed type, bottom depth and water constituents from hyperspectral imagery. However, low signal-to-noise ratios (SNR) due to low water-leaving radiance combined with environmental variability make it very difficult to design an optimal processing algorithm. Here, we selected a state-of-the-art, forward semi-analytical model in which we included a mixing model of four seabed albedo, namely sand, corals, algae and seagrass. The purpose of this paper was then to compare different setups of the inversion scheme, each one having its own theoretical strengths and weaknesses regarding the different confounding factors. Six inversion setups were implemented, corresponding to the combinations between (i) three cost functions: least square (LS), spectral angle mapper (SAM) and least square on spectral derivative (LSD), and (ii) two physical constraints imposed on the seabed type retrieval: abundance sum-to-one constraint (ASC) and a relaxed version (RASC). Performances of bathymetry and seabed type retrieval were evaluated on hyperspectral data acquired in a coral reef environment in Réunion Island. Our results showed that the accuracy and robustness of the bathymetric estimation were greatly influenced by the choice of the inversion setup. RASC-LSD produced the overall best performances even if SAM-based inversion setups showed particularly low error dispersion with respect to Lidar derived bathymetry. RASC-LSD also produced the most accurate results in terms of spatial coverage of benthic components on a very shallow area (inner part of a fringing reef). The results on our study areas clearly highlighted the interest of relaxing the ASC when the bottom depth is shallow. In deeper areas, ASC versions of LS- and LSD-based inversion setups produced the best seabed type mapping results. Only broad seabed types could be retrieved in areas deeper than 10 m. © 2017 Elsevier Inc

Approaches To Automatic Data Processing In Hyperspectral Remote Sensing

International audienc

An Approach To Prediction Of Signal-Dependent Noise Removal Efficiency By Dct-Based Filter

International audienc

"Jamais on n'a \ue9t\ue9 plus mari que cela": \ue9bauche d'anthropomythie maritale dans le roman libertin

Il contributo si propone di esaminare alcuni romanzi libertini nei quali il personaggio del marito \ue8 meglio caratterizzato e in cui la sua presenza permea di s\ue9 la trama. Si giunge cos\uec a determinare il ruolo sociale del marito nel romanzo, fino a costituire una vera e propria antropomitia maritale

Pr\ue9faces d\u2019antiromans: la contrefa\ue7on pr\ue9facielle chez l\u2019abb\ue9 Laurent Bordelon

Il contributo intende dimostrare come le prefazioni degli "antiromanzi" dell'abate Lorent Bordelon mantengano il loro statuto testuale a dispetto dei procedimenti metafinzionali che vengono messi in atto dall'autore