Evaluation of forest fire risk by the analysis of environmental data and TM images

The evaluation of forest fire risk is an important issue in Mediterranean areas where the long arid season often creates favourable conditions for the occurrence of fires. In this Letter three indices related to this risk have been produced and compared for the western part of the Elba Island (Central Italy). The first index is based on the analysis of environmental information layers (topography, vegetation and soil type) within a Land Information System, while the other two are derived from a summer Landsat Thematic Mapper (TM) scene processed by unsupervised and supervised procedures, respectively. The results show the effectiveness of all these approaches, and, in particular, a greater accuracy of the supervised spectral index.     

An atmospheric correction method for the automatic retrieval of surface reflectances from TM images

Most of the atmospheric correction methods proposed in the literature are not easily applicable in reaJ cases. The most sophisticated models frequently require inputs which are not commonly available, whilst traditional simple dark object subtraction techniques do not generally give real reflectance values. In the present work an atmospheric correction method applicable to Landsat-TM data is described, which requires only inputs that are commonly available and the presence in the imaged scenes of some dark surfaces in TM bands 1 (blue) and 3 (red). The method consists of an inversion algorithm based on a simplified radiative transfer model in which the characteristics of atmospheric aerosols are estimated by the use of the path radiance in two TM bands rather than a priori assumed. On the basis of this information, which is crucial for determining the atmospheric properties, the retrieval of real reflectances from TM images is possible. The method can be applied to all TM scenes in which some dark points can be realistically supposed to be present, which is particularly advantageous in retrospective studies. Several TM scenes taken from different landscapes and in different seasons were corrected using the model. The reflectance values found were tested against ground measurements and compared with data from the literature. The results show a substantial improvement in the accuracy of the reflectance estimates with respect to estimates without atmospheric correction. Given some care in the identification of dark values, the relative error in actual reflectance retrieval is always rather low (?10–20 per cent); this error can be considered acceptable for most practical applications.     

Environmental monitoring and crop forecasting in the Sahel through the use of NOAA NDVI data. A case study: Niger 1986–89

Abstract

Several investigations have shown that NOAA NDVI data accumulated during a rainy season can be related to total rainfall or final primary productivity in the Sahel. However, serious problems can arise when looking for quantitative relations to monitor and forecast crop yield from NDVI values. Geographical variability can affect such relations, while the use of data taken from a whole season is impractical for forecasting. The present paper proposes a complete methodology of NDVI data processing which only utilizes NOAA AVHRR scenes from the first part of successive rainy seasons. A series of basic corrections are first applied to the original data to obtain reliable NDVI maximum value composites at the middle of the rainy seasons considered. Next, the variability in land resources is accounted for by means of a standardization process which normalizes the mean NDVI levels of some areas on the relevant multi-temporal averages and standard deviations. In this way, good estimates of the actual condition of vegetation can be obtained in relation to the local seasonal trend

The methodology was applied to the Sahelian sub-departments of Niger with data from four years (1986–1989). The most interesting result achieved concerns the estimation of final grain (millet and sorghum) yield for the sub-departments by the end of July with a mean error of about 0·08 T ha ^?1. This timely evaluation could be of great utility in the context of an efficient drought early warning system.     

THE USE OF RHEOLOGY TO CHARACTERIZE FLOW BEHAVIOR OF LIQUORICE SOLUTIONS

The rheological behavior of liquorice solutions at different concentrations (ranging between 30 and 60 Brix) and temperatures (in the range between 25 and 80C) has been investigated performing both dynamic tests in the linear viscoelastic region and steady shear tests, in 0.1–100 s^?1 shear rate range, by using a stress controlled rheometer (DSR 200, Rheometric Scientific, USA) and parallel plate geometry (φ = 40 mm). Small amplitude oscillations has shown the presence of both moduli also at the lowest tested concentration, with G′ greater than G″, except for the 30 Brix sample. It has been found that experimental viscosity data show a good agreement with a power law model, thus allowing the estimation of both the friction factor and the pressure drops in a typical pipeline used for liquorice solution conveying. It has been observed that the assumption of Newtonian behavior can lead to the erroneous design of the apparatuses that have to process liquorice extracts.     

A UNIFIED COLLOCATION ALGORITHM FOR PACKED-BED CHEMICAL REACTOR SIMULATION

Mathematical models of packed-bed catalytic reactors are aimed to predict the conversions and temperature profiles in both fluid and solid phases within the reactor. Although very general models can be mathematically formulated, usually several simplifying hypothesis are introduced for the fluid phase and/or the solid phase, in order to overcome computational difficulties

We describe in this paper a computational algorithm based on Orthogonal Collocation Method on finite elements, with elimination of the knot unknown functions, coupled with an integration method for stiff ordinary differential equations. This has been used in the development of a computer code, which allows us to find the transient behavior of the reactor by solving the equation relative to the external field, coupled with those describing the transient behavior in the catalyst particles, for a wide class of reactor models. The most general examined model includes axial dispersion in the external fluid phase, interphase mass and heat transfer resistances, intraphase mass resistance and any given kinetic scheme with complex reaction rate expressions.     

Mesenchymal stem cells,secretome and biomaterials in <i>in-vivo</i> animal models: Regenerative medicine application in cutaneous wound healing

The treatment of nonhealing and chronic cutaneous wounds still needs a clinical advancement to be effective. Both mesenchymal stem cells (MSCs), obtained from different sources, and their secretome derived thereof (especially exosomes) can activate signaling pathways related to promotion of cell migration, vascularization, collagen deposition, and inflammatory response demonstrating prohealing, angiogenetic and anti-scarring capacities. On the other hand, biodegradable biomimetic scaffolds can facilitate endogenous cell attachment and proliferation as well as extracellular matrix production. In this Review, we revise the complex composites made by biomimetic scaffolds, mainly hydrogels, and MSC-derived exosomes constructed for cutaneous wound healing. Studies demonstrate that there exists a synergistic action of scaffolds with encapsulated exosomes, displaying a sustained release profiles to facilitate longlasting healing effects. It can be envisioned that dressings made by biomimetic hydrogels and MSC-derived exosomes will be clinically applied in the near future for the effective treatment of nonhealing and chronic wounds.     

Eco-climatic classification of Tuscany through NOAA-AVHRR data

Eco-climatic classifications have proved to be of great utility for the planning and management of various agricultural and forestry activities. Since the usual methods are often expensive and not easy to apply, remote sensing data processing has recently been proposed to identify ecologically homogeneous land units. NOAA AVHRR data in particular have been demonstrated to be suitable for this purpose thanks to their spatial resolution and frequent acquisition. While most works in this field have dealt only with NDVI imagery, it has been suggested that thermal and ancillary data could also bring significant information. These considerations have been kept in mind during the present study, which concerns the eco-climatic classification of a complex Italian Region by the use of NOAA NDVI and thermal images from two years in addition to ancillary data. A complete methodology was developed for the processing of this integrated data set with particular reference to the identification of the suitable numbers of main and sub-classes. The final output was compared to existing climatic and land use information about the region. The substantial agreement between these sources testifies to the eco-climatic value of the product obtained.     

EVIDENCE FOR THE PHOSPHORYLATION AND GLYCOSYLATION OF THE AMARANTH 11S GLOBULIN (AMARANTHIN)

A series of 11S globulins isolated and purified from genetically different Amaranthus lines were found to be both glycosylated and phosphorylated to varying degrees, i.e., 4.0–7.8% and 0.030–0.058%, respectively. Carbohydrate was found to be N-linked to amino acids in the amaranth globulin and was composed of 28.0% xylose, 34.4% mannose 8.3% galactose and 29.3% glucose whereas phosphate was found to be O-linked with six residues per globulin molecule. Both co- or post-translational modifications were found to influence the hydrophilicity, surface charge characteristics and stability of the secondary conformation of the globulin. Glycosylation was shown to be important in the folding and assembly of the globulin, whereas phosphorylation was found to enhance the metal-binding capacity of the globulin.     

Collective communication operations: experimental results vs. theory

Collective communication operations (CCOs) are one of the most powerful tools for parallel processing on distributed memory architectures. From the theoretical viewpoint there has been a major effort in the design of optimal algorithms for these operations, especially for massive parallel processors (MPPs). However, in spite of the increasing availability of MPPs, there are just a few limited experimental checks of the different theories, so the assessment of their real value is not easy. The aim of the present paper is to address such issues for the most common CCOs, considering practical algorithms that can be included in a generic communication library. The main result is a new algorithm for building a quasi-optimal broadcast tree that is much simpler than, and as efficient as, previously available algorithms. To investigate the advantages and drawbacks of the proposed algorithms, a large set of experimental data has been collected on an IBM SP2 parallel system. The data demonstrate the efficiency of our approach in a number of interesting cases. Finally, all the experimental results have been related to the model used in designing the algorithms. © 1998 John Wiley & Sons, Ltd.