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O monitoramento de parâmetros indicadores da qualidade da água em reservatórios é uma necessidade prevista em lei, uma vez que a demanda pelos recursos hídricos expandiu-se em razão das suas múltiplas finalidades. Sensores remotos passivos mensuram a reflectância da radiação solar na superfície da água permitindo que parâmetros não-opticamente ativos sejam avaliados pela inferência de parâmetros opticamente ativos. Considerando que modelos empíricos dificilmente são empregados em áreas diferentes daquelas onde foram concebidos, o objetivo deste trabalho consiste em aplicar modelos de parâmetros não-opticamente ativos, desenvolvidos anteriormente (outubro/2019) em dados coletados em outra época (maio/2020), considerando o mesmo reservatório (Reservatório de Três Marias/MG), de forma a avaliar a replicabilidade destes modelos. Empregou-se a abordagem desenvolvida por Pizani et al. (2020) utilizando as mesmas bandas espectrais como preditores em análise de regressão múltipla para os parâmetros: condutividade elétrica, sólidos dissolvidos totais e oxigênio dissolvido. Os resultados indicam elevado coeficiente de determinação entre dados medidos in situ e a reflectância espectral com destaque para o melhor desempenho do sensor MSI/Sentinel-2 (r2 > 0,71) comparado ao sensor OLI/Landsat (r2 > 0,50). Estes resultados mostram avanços da pesquisa para o monitoramento remoto, que possibilita a redução de custos para os órgãos públicos ou privados.

The increased availability of remote sensing data associated with good revisit capabilities promotes the use of these data to estimate hydrological variables such as river width. This becomes espec...

A method is presented to produce river cross section profiles from a time series of Sentinel-1 images paired with water level data. Four programs are presented that generate river width data and cross section profiles from SAR or optical images. The programs generate a river bank and island width database with minimum manual intervention. Water level data from in situ stations are interpolated to match the width data and create elevation points from which the cross section profiles are produced. The method is fully described and tested on the São Francisco River in Brazil. The width data are plotted against discharge data to compare their progression. Over 1700 cross sections were produced and classified by their shape. Potential and limitations are presented.

The “Mean Ordinary Flood Line” (MOFL) is a conceptual line adopted by Brazil’s Federal Government to delineate land within the floodplain under its ownership and jurisdiction having major social implications. Past attempts at the cartography of this line have encountered strong difficulties brought either by a low precision or an excessive cost. In this article, we propose a method based on historical water gauge data to determine the water level corresponding to the MOFL. Satellite images coincident with past dates when the MOFL was reached are selected and processed to extract the water surface from which the MOFL can then be produced. The approach was implemented in a 600 km reach of the São Francisco River in Minas Gerais as a pilot project. A field survey served to validate the results. The positional accuracy of the MOFL was estimated at 24 m which was considered excellent since mostly Landsat images with a spatial resolution of 30 m were used.

The low operational cost of using freely available remote sensing data is a strong incentive for water agencies to complement their field campaigns and produce spatially distributed maps of some water quality parameters. The objective of this study is to compare the performance of Sentinel-2 MSI and Landsat-8 OLI sensors to produce multiple regression models of water quality parameters in a hydroelectric reservoir in Brazil. Physical-chemistry water quality parameters were measured in loco using sensors and also analysed in laboratory from water samples collected simultaneously. The date of sampling corresponded to the almost simultaneous overflight of Sentinel-2B and Landsat-8 satellites which provided a means to perform a fair comparison of the two sensors. Four optically active parameters were considered: chlorophyll-a, Secchi disk depth, turbidity and temperature (the latter using Landsat-8 TIR sensor). Other six optically non-active parameters were also considered. The multiple regression models used the spectral reflectance bands from both sensors (separately) as predictors. The reflectance values were based on averaging kernels of 30 m and 90 m. Stepwise variable selection combined with a priori knowledge based on other studies were used to optimize the choice of predictors. With the exception of temperature, the other optically active parameters yielded strong regression models from both the Sentinel and Landsat sensors, all with r2 > 0.75. The models for the optically non-active parameters produced less striking results with r2 as low as 0.03 (temperature) and as high or better than > 0.8 (pH and Dissolved oxygen).

This article describes a new algorithm for the detection and delineation of tree crowns using optical sub-meter resolution satellite images. The algorithm focuses on detecting individual semi-isolated trees in a variety of environments defined as trees outside forests (TOF). The concept of Marked Point Processes (MPPs), which alternates phases of “birth” and “death” iterations to satisfy a density factor was used as a theoretical basis. The “mark” in the MPP represents the object being sought. Unlike most applications of MPP to object recognition, the mark used in our algorithm is computed from a 3D geometrical optical model artificially lit using the same illumination parameters as the image itself. Because trees differ in size, the process also incorporates a tree crown radius variable. The algorithm is tested on four sub-meter satellite images, each in a different environment. Validation was performed on both detection and delineation. The detection was based on tree crown counting and yielded an accuracy ranging from 0.81 to 0.95 for the four images. The delineation accuracy was estimated based on the crown pixel count and yielded an accuracy of ≈ 0.63 (0.57–0.72).

The proof of concept for two-photon activated photodynamic therapy has already been achieved for cancer treatment but the efficiency of this approach still heavily relies on the availability of photosensitizers combining high two-photon absorption and biocompatibility. In this line we recently reported on a series of porphyrin-triphenylamine hybrids which exhibit high singlet oxygen production quantum yield as well as high two-photon absorption cross-sections but with a very poor cellular internalization. We present herein new photosensitizers of the same porphyrin-triphenylamine hybrid series but bearing cationic charges which led to strongly enhanced water solubility and thus cellular penetration. In addition the new compounds have been found localized in mitochondria that are preferential target organelles for photodynamic therapy. Altogether the strongly improved properties of the new series combined with their specific mitochondrial localization lead to a significantly enhanced two-photon activated photodynamic therapy efficiency.

Zusammenfassung Additive Fertigungstechnologien wurden in den vergangenen Jahren bzgl. Verfahren und Druckmaterialien weiterentwickelt, so dass heute Freiformoptiken in optischer Güte durch 3D-Drucker gedruckt werden können. Durch die schnelle Fertigung von Freiformoptiken entstehen neue Möglichkeiten für die optische Messtechnik, da durch Variation der Form und Größe von Optikelementen mit geringem Aufwand spezifisch an Applikationen angepasste Sensorsysteme gefertigt werden können. In diesem Beitrag werden nun exemplarisch zwei Sensorapplikationen aus dem Bereich der industriellen In-Line-Messtechnik dargestellt, die jeweils ein additiv gefertigtes Optikelement enthalten. Zunächst wird ein auf Lasertriangulation basierendes Sensorsystem zur Vermessung von Turbinenschaufeln dargestellt. Dieses System beinhaltet eine additiv gefertigte transparente Freiformoptik im Beleuchtungsstrahlengang, die zur lückenlosen Generierung einer Laserlinie auf einer komplexen 3D-Oberfläche genutzt wird. Im zweiten Applikationsbeispiel wird ein miniaturisierter Sensor beschrieben, der die dreidimensionale Erfassung des Innenraums von kleinen Kavitäten ermöglicht. Dieses auf dem Lichtschnittprinzip basierende System beinhaltet ein gedrucktes Spiegelelement, durch das ein spezifisches Abtastsignal innerhalb einer Kavität erzeugt wird.

Non-point and point source pollution are a water quality problem in most parts of the World. Many studies have used the land use and land cover (LULC) to model non-point pollution sources. In this article we evaluate the relationship between LULC and five water quality parameters using different zones of analysis: riparian buffers (B) and exclusive contribution areas (ECA). The five parameters are nitrate, nitrite, total ammonia nitrogen, total phosphorous and dissolved oxygen. Analyses were performed on riparian zones of different widths and ECAs to verify if the effect of the land cover on the water quality of the stream decreases with the increased distance. The urban and agricultural/pasture categories of LULC were characterized as pollution sources while vegetation (Forest and Riparian Forest) as pollution sink (filter). We proposed a Land Cover Pollution index (LCPI) which is a ratio between source and sink to substitute the individual LULC categories. The source and sink categories were selected considering our knowledge of the LULC relationship and the sign of the Pearson's Correlation Coefficient. The LCPI varied between 0.11 in the 150 m buffer (higher filter effect) and a maximum of 27.99 (largest source effect). Additionally, we transformed the water quality data in incremental loads per unit area so that each station could be considered independent from the others and be compared between themselves independently of the contribution area they represent. Our method also included only data from the rain season, the beginning of which was determined using the hydrograms of discharge data. Results indicate that the index is better than the individual LULC classes to explain this relationship, especially in riparian zones. In 12 out of 15 models the coefficient of determination (R2) increased by 11 to 155%, when we use the index instead of the LULC classes. We believe that these good results can be attributed to the LCPI but also to the special processing of the water quality data making it more sound for statistical processing.

Porphyrin- or phthalocyanine-bridged silsesquioxane nanoparticles (BSPOR and BSPHT) were prepared. Their endocytosis in MCF-7 cancer cells was shown with two-photon excited fluorescence (TPEF) imaging. With two-photon excited photodynamic therapy (TPE-PDT), BSPOR was more phototoxic than BSPHT, which in contrast displayed a very high signal for photoacoustic imaging in mice.

Depuis plusieurs milliers d'années, la lumière qu'elle soit naturelle ou artificielle a été utilisée comme traitement de maladies de la peau, des yeux ou contre le cancer. Ce n'est qu'au début du XXe siècle que la science s'est intéressée aux interactions « lumière-vivant ». La compréhension de l'action conjuguée, dénommée « photothérapie dynamique », d'un médicament non toxique à l'obscurité, de l'oxygène et de la lumière a permis de mettre au point un protocole d'éradication de tumeurs bénignes ou malignes et d'anomalies vasculaires. Depuis environ 30 ans, on voit apparaître de nombreuses molécules photoactivables de plus en plus efficaces. Peu de molécules photosensibles ont encore atteint le stade clinique, mais les résultats publiés dans la littérature scientifique montrent que la photothérapie dynamique est en plein développement et a un avenir certain [1-3].

Satellite altimetry is becoming a major tool for measuring water levels in rivers and lakes offering accuracies compatible with many hydrological applications, especially in uninhabited regions of difficult access. The Pantanal is considered the largest tropical wetland in the world and the sparsity of in situ gauging station make remote methods of water level measurements an attractive alternative. This article describes how satellites altimetry data from Envisat and Saral was used to determine water level in two small lakes in the Pantanal. By combining the water level with the water surface area extracted from satellite imagery, water volume fluctuations were also estimated for a few periods. The available algorithms (retrackers) that compute a range solution from the raw waveforms do not always produce reliable measurements in small lakes. This is because the return signal gets often “contaminated” by the surrounding land. To try to solve this, we created a “lake” retracker that rejects waveforms that cannot be attributed to “calm water” and convert them to altitude. Elevation data are stored in a database along with the water surface area to compute the volume fluctuations. Satellite water level time series were also produced and compared with the only nearby in situ gauging station. Although the “lake” retracker worked well with calm water, the presence of waves and other factors was such that the standard “ice1” retracker performed better on the overall. We estimate our water level accuracy to be around 75 cm. Although the return time of both satellites is only 35 days, the next few years promise to bring new altimetry satellite missions that will significantly increase this frequency.

This article presents an original algorithm created to detect and count trees in orchards using very high resolution images. The algorithm is based on an adaptation of the “template matching” image processing approach, in which the template is based on a “geometricaloptical” model created from a series of parameters, such as illumination angles, maximum and ambient radiance, and tree size specifications. The algorithm is tested on four images from different regions of the world and different crop types. These images all have < 1 meter spatial resolution and were downloaded from the GoogleEarth application. Results show that the algorithm is very efficient at detecting and counting trees as long as their spectral and spatial characteristics are relatively constant. For walnut, mango and orange trees, the overall accuracy was clearly above 90%. However, the overall success rate for apple trees fell under 75%. It appears that the openness of the apple tree crown is most probably responsible for this poorer result. The algorithm is fully explained with a step-by-step description. At this stage, the algorithm still requires quite a bit of user interaction. The automatic determination of most of the required parameters is under development.

Fourier Transform Infrared (FTIR) microspectroscopy was used to highlight the interactions between two photosensitisers (PS) of different geometries, TPPmOH4 and a glycoconjugated analogous, TPPDegMan, and lipid bilayers modelling retinoblastoma cell membranes. Retinoblastoma is a rare disease occurring in young infants, for whom conservative treatments may present harmful side-effects. Photodynamic therapy (PDT) is expected to induce less side-effects, as the photosensitiser is only activated when the tumour is illuminated. Since efficiency of the treatment relies on photosensitiser penetration in cancer cells, bilayers with three lipid compositions - pure SOPC, SOPC/SOPE/SOPS/Chol (56:23:11:10) and SOPC/SOPE/SOPS/Chol/CL (42:32:9:8:6) – were used as plasma and mitochondria model membranes. FTIR spectra showed that the interaction of the PSs with the lipid bilayers impacted the lipid organization of the latter, causing significant spectral variations. Both studied photosensitisers inserted at the level of lipid hydrophobic chains, increasing chain fluidity and disorder. This was confirmed by surface pressure measurements. Photosensitisers - TPPmOH4 more than TPPDegMan - also interacted with the polar region of the bilayer, forming hydrogen bonds with phosphate groups that induced major shifts of phosphate absorption bands. This difference in PS interaction with moieties in the polar region was more pronounced with the models with complex lipid composition.

Cerrado is a savannah biome covering about 60% of the State of Minas Gerais, Brazil, but with a rate of conversion that surpasses that of all other biomes in Brazil. Remote sensing is the only practical means of monitoring the conversion and regeneration of this vegetation formation. The objective of this article is to model the process of regeneration of Cerrado vegetation and to estimate its age using a RapidEye image mosaic and textural features derived from the grey-level co-occurrence matrix. The study area is Parque Estadual Veredas do Peruacu, a State Park in Minas Gerais, which was a plantation of eucalyptus until 1994 with a broad range of regeneration ages between 15 and 37 years. A total of 47 plots were surveyed for which the exact ages of regeneration are known and other structural variables were measured. Multiple regression and stepwise feature selection were used to create models that explain over 80% of the age, 58% of the crown closure, and 48% of the height of the vegetation. Texture proved essential for capturing the patterns of light and shadow generated by the trees of varying widths and heights.

International audience; A new family of amphiphilic glycoconjugated porphyrin dimers usable in two-photon photodynamic therapy was designed, prepared and characterized. The physicochemical and biological data were presented and discussed. Their two-photon absorption cross section was determined, revealing quite good performances of the compounds (d % 300 GM at 880 nm for 2 and 3 and d % 1000 GM at 840 nm for 5 and 6). Despite their promising photophysical properties, porphyrin dimers are penalized by their low solubility and an insufficient penetration into tumour cells. Incorporation into nanocarriers such as lipid vesicles could be profitable, provided that the positioning and degree of freedom of the saccharide moieties are optimal to target the receptors of the cells of interest.

Land use in a watershed can be responsible for the loss or preservation of the quality of its superficial waters. This especially true for non-point water pollution. Decision trees are machine learning techniques with promising applications in this type of research. A decision tree model follows a hierarchical structure that aims at finding hidden patterns within complex databases and predict the behavior of a class (explained variable) from the independent variables. The methodology used in this article evaluates the applicability of decision trees to study the relationship water discharge – land use – non-point pollution. The Velhas River watershed and the water quality parameters nitrate and phosphorous were chosen as the objects of investigation. Water quality data from 17 stations and discharge data from 8 fluviometric stations, all within the main river channel of the Velhas River were used to carry out our study. Eight categories of land use data were extracted from mosaic of 72 RapidEye images. The decision trees were generated using Quinlan’s C4.5 algorithm which created sets of rules associating land use categories to variations of nitrate and phosphorous therefore identifying which ones are the main responsible for loss of water quality. The resulting decision trees were able to correctly classify over 80% of the instances of discrete nitrate and phosphorous classes. However, some shortcomings were also identified and were mainly attributed to the relatively low volume of water quality data

Biodegradable bridged silsesquioxane (BS) nanomaterials for two-photon-excited (TPE) imaging and therapy of breast cancer cells were described. A versatile synthesis was developed to design monodisperse tetra-alkoxysilylated diamino-diphenylbutadiene or Zn-porphyrin-based nanospheres of 30 to 50 nm.

Riparian formations are often narrow strips of vegetation near the banks of streams governed by good water availability. With the advent of high-resolution satellite imagery, the study of riparian forests using space-borne remote sensing has gained more attention. However, the sole use of remotely sensed data is seldom sufficient to delineate riparian forests and their special hydrological and geomorphological context should also be considered. In this study, we propose a twofold method to delineate riparian forests in a Brazilian savannah context. Four sites on the banks of the Pandeiros River were used to test our approach, each in a different hydrological context. In our approach, the hydrographic network and a digital surface model are processed using the depth-to-water analysis to create a mask of the riparian zone, then the riparian forests are extracted using region-based image classification. Both steps are fully explained. Three region-based image classification programs e-Cognition, Sistema de Processamento de Informacoes Georeferenciadas SPRING, and MAGIC map-guided ice classification are briefly described and tested. A special validation scheme was created using the independent interpretation of five photo-interpreters to test the accuracy of the results. All three programs achieved a success rate of over 90%. The approach is also tested on a much larger area of the Pandeiros River to assess its applicability in a more operational context. The discussion focuses on methodological issues and the advantages and drawbacks of the approach.

The development of additive manufacturing methods has enlarged rapidly in recent years. Thereby, the work mainly focuses on the realization of mechanical components, but the additive manufacturing technology offers a high potential in the field of optics as well. Owing to new design possibilities, completely new solutions are possible. This article briefly reviews and compares the most important additive manufacturing methods for polymer optics. Additionally, it points out the characteristics of additive manufactured polymer optics. Thereby, surface quality is of crucial importance. In order to improve it, appropriate post-processing steps are necessary (e.g. robot polishing or coating), which will be discussed. An essential part of this paper deals with various additive manufactured optical components and their use, especially in optical systems for shape metrology (e.g. borehole sensor, tilt sensor, freeform surface sensor, fisheye lens). The examples should demonstrate the potentials and limitations of optical components produced by additive manufacturing.

Non-point source water pollution is a major problem in most parts of the world, but is also very difficult to quantify and control since it is not easily separated from point sources and can theoretically originate from the whole watershed. In this article, we evaluate the relationship between land use and land cover and four water pollution parameters in a watershed in Southeast Brazil. The four parameters are nitrate, total ammonia nitrogen, total phosphorous, and dissolved oxygen. To help concentrate on non-point source pollution, only data from the wet seasons of the time period (2001-2013) were analysed, based on the fact that precipitation causes runoff which is the main cause of diffuse pollution. The parameters measured were transformed into loads, which were in turn associated with an exclusive contribution area, so that every measuring station could be considered independent. Analyses were also performed on riparian zones of different widths to verify if the effect of the land cover on the water quality of the stream decreases with the increased distance. Pearson correlation coefficients indicate that urban areas and agriculture/pasture tend to worsen water quality (source). Conversely, forest and riparian areas have a reducing effect on pollution (sink). The best results were obtained for total ammonia nitrogen and dissolved oxygen using the whole exclusive contribution areas with determination coefficients better than R (2)≈0.8. Nitrate and total phosphorous did not produce valid models. We suspect that the transformation delay from total ammonia nitrogen to nitrate might be an important factor for the poor result for this parameter. For phosphorous, we think that the phosphorous sink in the bottom sediment might be the most limiting factor explaining the failure of our models.

Resume Introduction Les porphyrines sont des photosensibilisateurs applicables a la therapie photodynamique des cancers. Bien qu’efficaces, elles presentent deux inconvenients majeurs, une faible solubilite en milieu aqueux et une absence de specificite. L’objectif de notre etude etait d’analyser le comportement interfacial de tetraphenylporphyrines glycoconjuguees synthetisees a l’Institut Curie, ainsi que leur interaction avec des membranes modeles portant une lectine specifique, mimant un recepteur membranaire a mannose des cellules de retinoblastome. Materiel et methodes Le comportement interfacial des derives porphyriniques a ete determine par des mesures de pression de surface et leur interaction avec la lectine, par des mesures de diffusion quasi-elastique de la lumiere (liposomes) et par la technique de la microbalance a cristal de quartz (bicouches planes supportees). Resultats Tous les derives porphyriniques etudies sont tensioactifs et s’organisent a l’interface. Les composes dendrimeriques forment des monocouches plus stables que les autres a l’interface et se melangent generalement bien au phospholipide constituant la membrane de liposomes. En presence de concanavaline A, les liposomes se comportent differemment selon qu’ils vehiculent des porphyrines mannosylees ou le derive non glycoconjugue. Discussion Le comportement interfacial des tetraphenylporphyrines est directement lie a l’orientation du macrocycle tetrapyrrolique imposee par ses substituants. Incorporees dans la membrane de liposomes, les porphyrines glycodendrimeriques s’orientent, exposant les sucres a la surface des liposomes. La longueur de l’espaceur joue un role crucial en permettant une meilleure mobilite des sucres et une interaction plus significative avec la lectine. Conclusion Comparees aux autres substances etudiees, les porphyrines glycodendrimeriques apparaissent particulierement prometteuses et font l’objet d’une evaluation in vitro sur cultures cellulaires.

In this paper, we report the synthesis of a series of porphyrins, designed as photodynamic therapy (PDT) agents, substituted by three glycosyl units linked by a triazole group to chromophore in the aim to target tumor cells overexpressing lectin-type membrane receptors, by ‘click-chemistry’ under microwave heating.

We report the synthesis of a series of zinc porphyrins conjugated with pyrimidine derivatives. V shaped porphyrin dimer with a pyrimidine central core exhibits a planar geometry according to DFT computational studies, presents an internal charge transfer upon excitation proved by typical solvatochromic behavior and moderate two-photon absorption properties. Such porphyrin conjugates can afford valuable advantages in applications of TPA materials such as in photodynamic therapy and imaging of biological entities.

Background: Porphyrins are a group of heterocyclic macrocycle organic compounds. They have shown good efficiency in the photodynamic treatment of tumors in the last twenty years. The photodynamic therapy could be an alternative treatment for retinoblastoma using a photosensitizer with low dark toxicity and low mutagenic properties unlike the conventional chemotherapies. The objectives of this study were to develop a photosensitizer in our lab which is a diethylene glycol mannoconjugated tetraphenyl porphyrin (TPP, MW: 1413.6) and to determine the optimal interval time for photodynamic therapy using the concentration of TPP in eye and blood samples of mice. Materials and method: Transgenic mice developed bilateral retinoblastoma from the retina since 4 weeks of age to 16 weeks of age (tumors fill the ocular globe and the mice will be sacrificed for ethic purpose). The evaluation of the biodistribution of our TPP was realized to know the best drug-light interval to perform the photodynamic therapy. For this purpose, an intraperitoneal injection of 200 µl at 5.25 mg/ml in PEG 400/physiological serum (1:1, v/v) was performed on the LHbetaTag transgenic mice. At different time intervals (8h, 24h, 40h, 48h, and 72h) following injection, the mice were sacrificed and the eyes and blood were collected. TPP in eye samples were extracted in methanol and the level of TPP was measured by ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) analysis (0.5-100 ng/mL). The level of TTP in blood samples was quantified after protein precipitation by UPLC-MS/MS method (5.00-1000 ng/mL). Results: We observed a time dependency accumulation of TPP in eyes with observed Tmax=48 hours. TPP serum concentrations decreased by the same manner up to 48 h. The determination of drug-light interval allowed us to perform the light delivery when the TPP level is highest (48 h) in the ocular tumor tissue (retinoblastoma). Conclusions: Our TPP had a good in vitro photocytotoxicity at very low doses and showed a good efficacy in vivo with subcutaneous patient derived retinoblastoma xenografts in immunodeficient mice. The knowledge of Tmax and this interval is essential to realize the photodynamic therapy with the better efficiency, the final goal being to eradicate the retinoblastoma from the retina. Citation Format: Florent Poyer, Samuel Hugeut, Stéphanie Lemaitre, Olivier Madar, Carole D Thomas, Philippe Maillard, Marie-Paule Teulade-Fichou, Nathalie Cassoux, François Doz, Keyvan Rezai. Evaluation of porphyrin biodistribution for use in photodynamic therapy of retinoblastoma in transgenic mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3213.

Cerrado is a woody savanna formation covering about one fifth of Brazil with a very complex structure and rich biodiversity. Its rate of conversion surpasses that of all other biomes in Brazil. Remote sensing is the only practical means to monitor the evolution of its conversion and regeneration. The objective of this article is to study the process of regeneration of cerrado vegetation after being a eucalyptus plantation for two decades and to estimate its age using multitemporal Landsat Thematic Mapper (TM) data. The study area is a state park in Minas Gerais that was a eucalyptus plantation until 1994 with a broad range of regeneration ages between 13 and 34 years. A total of 47 plots were surveyed for which the exact ages of regeneration are known. Eighteen Landsat TM images were digitally processed to model the reflectance trajectory of the regenerating cerrado and determine its age. Results show that spectral data can be used for estimating the age regeneration up to 30 years with an average accurac...

The Pandeiros is a unique wetland in northern Minas Gerais, Brazil. Even though it is an official wildlife sanctuary, it suffers from increasing degradation because of livestock grazing and other forms of human activity. The absence of specific laws defining and protecting wetlands in Brazil is partly responsible for this situation. Having no official designation, most environments of the Pandeiros have not yet been identified or characterized as wetlands. This article presents a comparison between an unsupervised region-based classification approach and traditional supervised and unsupervised classification techniques for mapping different environments within this complex wetland system. All three classification methods were tested and their results compared with field data and with an interpreted reference map. The results suggest that the traditional supervised classification approach and the new region-based approach have good potential for identifying the main vegetal physiognomies, but the latter yi...