Modeling the impact of spectral sensor configurations on the FLD retrieval accuracy of sun-induced chlorophyll fluorescence

Chlorophyll fluorescence is related to photosynthesis and can serve as a remote sensing proxy for estimating photosynthetic energy conversion and carbon uptake. Recent advances in sensor technology allow remote measurements of the sun-induced chlorophyll fluorescence signal (Fs) at leaf and canopy scale. The commonly used Fraunhofer Line Depth (FLD) principle exploits spectrally narrow atmospheric oxygen absorption bands and relates Fs to the difference of the absorption feature depth of a fluorescensing and a non-fluorescensing surface. However, due to the nature of these narrow bands, Fs retrieval results depend not only on vegetation species type or environmental conditions, but also on instrument technology and processing algorithms. Thus, an evaluation of all influencing factors and their separate quantification is required to further improve Fs retrieval and to allow a reproducible interpretation of Fs signals.Here we present a modeling study that isolates and quantifies the impacts of sensor characteristics, such as spectral sampling interval (SSI), spectral resolution (SR), signal to noise ratio (SNR), and spectral shift (SS) on the accuracy of Fs measurements in the oxygen A band centered at 760 nm (O₂-A). Modeled high resolution radiance spectra associated with known Fs were spectrally resampled, taking into consideration the various sensor properties. Fs was retrieved using the three most common FLD retrieval methods, namely the original FLD method (sFLD), the modified FLD (3FLD) and the improved FLD (iFLD). The analysis investigates parameter ranges, which are representative for field and airborne instruments currently used in Fs research (e.g., ASD FieldSpec, OceanOptics HR, AirFLEX, AISA, APEX, CASI, and MERIS).Our results show that the most important parameter affecting the retrieval accuracy is SNR, SR accounts for ≤ 40% of the error, the SSI for ≤ 12%, and SS for ≤ 7% of the error. A trade-off study revealed that high SR can partly compensate for low SNR. There is a strong interrelation between all parameters and the impact of specific parameters can compensate or amplify the influence of others. Hence, the combination of all parameters must be considered by the evaluation of sensors and their potential for Fs retrieval. In general, the standard FLD method strongly overestimates Fs, while 3FLD and iFLD provide a more accurate estimation of Fs. We conclude that technical sensor specifications and the retrieval methods cause a significant variability in retrieved Fs signals. Results are intended to be one relevant component of the total uncertainty budget of Fs retrieval and have to be considered in the interpretation of retrieved Fs signals.     

Inversion of a radiative transfer model with hyperspectral observations for LAI mapping in poplar plantations

The potential of radiative transfer modelling and inversion techniques for operational uses is investigated in order to retrieve leaf area index in a poplar plantation. The 1-D bidirectional canopy reflectance model SAIL, coupled with the leaf optical properties model PROSPECT, was inverted with hyperspectral airborne DAIS data by means of an iterative method. The root mean square error in LAI estimation was determined against in situ measurements in order to evaluate the impact of different inversion strategies on the LAI retrieval accuracy. These included the selection of an optimal spectral sampling set, the exploitation of prior knowledge in the inversion process and the use of multiview angle data. We claim that the best configuration is achieved by exploiting multiview DAIS data and prior knowledge information about the model variables (RMSE of 0.39 m² m⁻²). It is also shown that the use of prior knowledge and the selection of a limited number of bands forming the optimal spectral sampling are instrumental in increasing the accuracy of the inversion process. Our analysis confirms the operational potential of model inversion for biophysical parameter retrieval.     

Fracture behaviour of single crystal silicon microstructures

The fracture behaviour of single crystal silicon (SCSi) microstructures is analysed based on microme-chanical torsional and tensile experiments. The uniaxial testpieces are characterised by the presence of sharp not-ches at the gauge length extremities. The critical loading conditions are reproduced in a finite element model in order to identify the analogies of the failure conditions in tension and torsion. The stress field in the vicinity of the notch tip (were cracks originate) is analyzed, and fracture mechanics parameters are determined. In the finite element model a crack, reproducing the failure process observed in the experiments, is included. The crack area is incrementally increased and the energy release rate for the critical loading conditions in tension and torsion is calculated. Based on these results a failure criterion is formulated along with a procedure for the mechanical integrity analysis of SCSi microstructures of arbitrary shape and loading conditions.     

Optimisation of opaque components of the building envelope. Energy,economic and environmental issues

The European Directive 2002/91 will enforce the Member State to promote the implementation of new measures, instruments and calculation methodology to improve the buildings energy performances. The thermal performance and quality of the Italian residential buildings is generally poor, depending on the age of the building stock and the lack of application of the existing energy regulations. This study aims at demonstrating the global benefits of good insulated building envelopes. Energy benefits are easy to understand, meanwhile the economic issues are critical, since the final users see them as an additional useless extra cost for the dwelling at the purchase phase, with small attention to the future managing costs. The study demonstrates that significant economic advantages come out from high–performance building envelope. The study also shows that environmental extra loads due to a bigger use of the insulating material is paid back in few years, with consistent social benefits, if the life cycle of the building is taken into account.     

Experimental analysis of the energy performance of a passive attached sunspace

During the studies carried out at the Institute for Building Technology of the National Research Council (ICITE), a method has been developed to analyse the energy performance of passive solar components in the building industry by using test cells that simulate a conventional dwelling environment. The paper describes the tested components, the experimental analysis of energy performance that has been carried out, the complementary analysis performed, and the obtained results.     

Change in visual function and viewing distance during work with VDTs

Seven female volunteer bank clerks aged between 24 and 32 yr were selected for a laboratory trial after a preliminary ocular examination which showed them to be emmetropic or slightly myopic (less than or equal to 1D) and to have normal ocular motility or only minor deficiencies. Near and far point refraction and phorias and near point fusional vergences were measured before and immediately after a 6 h workday at a PC workstation. Eye screen distance (viewing distance) was monitored. Near and far distance refraction showed an increase and a decrease of accommodation in 13 out of 14 eyes respectively. Fusional convergence decreased in six out of seven cases: a smaller decrease in divergence was recorded in all subjects. These changes were statistically significant. Viewing distance, though showing some interindividual differences, increased considerably during the last 2 h of the trial, without reaching statistical significance.     

The anti-beta2-glycoprotein I activity in human anti-phospholipid syndrome sera is due to monoreactive low-affinity autoantibodies directed to epitopes located on native beta2-glycoprotein I and preserved during species' evolution

To characterize the reactivity pattern of Abs directed to beta2-glycoprotein I (anti-beta2GPI) in patients with anti-phospholipid syndrome, we have purified anti-beta2GPI Abs by affinity chromatography using the IgG fractions from sera of five different anti-phospholipid syndrome patients. Affinity-purified anti-beta2GPI were shown to be representative of Abs found in human sera because their activity could be virtually abolished from the IgG preparations after repeated absorptions on immobilized human beta2GPI column. Our results show that affinity-purified anti-beta2GPI: 1) do react with beta2GPI in the absence of any phospholipid, as demonstrated by the lack of phosphorus contaminant in the employed reagents, as well as by their comparable binding activity before and after extensive delipidation procedure; 2) can recognize beta2GPI regardless of its origin from different animal species; 3) are able to bind soluble beta2GPI with a mean Kd value of 4.65 x 10(-6) M (range 3, 4-7, 2 x 10(-6) M); 4) significantly enhance their binding avidity when beta2GPI is linked to a solid support; and 5) appear to be mainly monoreactive autoantibodies. In conclusion, we have shown that human polyclonal anti-beta2GPI are low affinity, mainly monoreactive autoantibodies directed to an epitope located on native beta2GPI, preserved along the species evolution.     

Primary chemoradiation therapy with fluorouracil and cisplatin for cancer of the anus: results in 35 consecutive patients

PURPOSE: This prospective phase II study was designed to test the activity and toxicity of a regimen of fluorouracil (5-FU) and cisplatin (CDDP) in combination with radiation therapy in the treatment of epidermoid cancer of the anal canal. PATIENTS AND METHODS: Thirty-five consecutive patients with untreated epidermoid cancer of the anal canal were candidates for chemoradiation therapy (CRT). Staging of cancer was as follows: T1, 26%; T2, 60%; T3, 14%; and N1, 2,3, 26%. No patient had distant metastases. The treatment protocol consisted of two to three cycles of chemotherapy starting on days 1 and 21 and concurrent radiotherapy at a daily dose of 1.8 Gy up to a total dose of 36 to 38 Gy in 4 weeks, delivered to the anal region, perineum, middle and lower pelvis, and inguinal and external iliac nodes. Radiotherapy was then delivered to the anoperineal region and metastatic inguinal nodes to a total dose of 18 to 24 Gy in 10 fractions. Chemotherapy consisted of 24-hour intravenous (IV) infusion of 5-FU 750 mg/m2 on days 1 to 4 and CDDP 100 mg/m2 by 60-minute IV infusion on day 1. RESULTS: All patients received two cycles of chemotherapy; the second was delayed in three patients because of leukopenia that was evident in 11 (31%). In eight patients, a third cycle was added. They all experienced nausea or vomiting; one patient showed signs of cardiotoxicity and one developed proctitis, dermatitis, and diarrhea (grade 3). Complete regression (CR) was assessed in 33 patients (94%); nine patients with metastatic lymph nodes also had CR. Two patients had a partial response (PR); both underwent abdominoperineal resection, which was not curative in one. Two patients (6%) had a local recurrence; in one, this was associated with hepatic metastases. One of these patients underwent surgery and is alive after about 4 years, while the other is undergoing chemotherapy. After a median follow-up duration of 37 months, 94% of patients are alive without evidence of disease and 86% are colostomy-free. CONCLUSION: This regimen is well tolerated; its toxicity does not exceed that observed with the combination of 5-FU and mitomycin (MMC). Compared with our previous experience based on the classic CRT (5-FU, MMC, and radiation), the objective response rate observed with this new combination was similar. However, the local recurrence rate, observed in patients treated with the new regimen, was lower (6% v 24%). According to more recent data from the literature, primary CRT is the elective indication in epidermoid cancer of the anus and replacement of MMC with CDDP seems an effective and logical evolution.     

On the adoption of blockchain for business process monitoring

Being the blockchain and distributed ledger technologies particularly suitable to create trusted environments where participants do not trust each other, business process management represents a proper setting in which these technologies can be adopted. In this direction, current research work primarily focuses on blockchain-oriented business process design, or on execution engines able to enact processes through smart contracts. Conversely, less attention has been paid to study if and how blockchains can be beneficial to business process monitoring. This work aims to fill this gap by (1) providing a reference architecture for enabling the adoption of blockchain technologies in business process monitoring solutions, (2) defining a set of relevant research challenges derived from this adoption, and (3) discussing the current approaches to address the aforementioned challenges.

     

Active packaging as an opportunity to create package design that reflects the communicational,functional and logistical requirements of food products

The packaging of industrial food products is the most important means of transmitting a product's image and taste value. When the nature of its interface and its contents are the product of carefully planned imaging, the product has notable advantages in defining its image and product identity. Modern food trends dictate an ever‐increasing amount of services: The so‐called ‘functional packaging’ and ‘active packaging’ are prime examples of this service. The greatest innovation within this category of products consists literally of their interaction with food. These features create numerous fallbacks within all stages of the life‐cycle of a product, requiring a complex and multidisciplinary evaluation. The evaluation strategy of services which this packaging will offer to the consumer is still to be defined, and still to be identified within the key applications are the interests of the intermediary links of the production process. This requires the evaluation of the semantic and communicative aspects of the packaging which tend to be confused with the foodstuffs, the individualization of appropriate user profiles, control of logistical and location aspect of production, and a careful analysis of a comprehensive environmental balance, all issues that are parts of the objectives of the European project, Actipak. It is hoped, therefore, that the elaboration of these packaging systems will become a motive to try out a more knowledgeable and systematic design process for foodstuffs, in which innovative technology is used to provide effective benefits to the consumer. Copyright © 2000 John Wiley & Sons, Ltd.