Pléiades project: Assessment of georeferencing accuracy, image quality, pansharpening performence and DSM/DTM quality

Pléiades 1A and 1B are twin optical satellites of Optical and Radar Federated Earth Observation (ORFEO) program jointly running by France and Italy. They are the first satellites of Europe with sub-meter resolution. Airbus DS (formerly Astrium Geo) runs a MyGIC (formerly Pléiades Users Group) program to validate Pléiades images worldwide for various application purposes. The authors conduct three projects, one is within this program, the second is supported by BEU Scientific Research Project Program, and the third is supported by TÜBİTAK. Assessment of georeferencing accuracy, image quality, pansharpening performance and Digital Surface Model/Digital Terrain Model (DSM/DTM) quality subjects are investigated in these projects. For these purposes, triplet panchromatic (50 cm Ground Sampling Distance (GSD)) and VNIR (2 m GSD) Pléiades 1A images were investigated over Zonguldak test site (Turkey) which is urbanised, mountainous and covered by dense forest. The georeferencing accuracy was estimated with a standard deviation in X and Y (SX, SY) in the range of 0.45m by bias corrected Rational Polynomial Coefficient (RPC) orientation, using ~170 Ground Control Points (GCPs). 3D standard deviation of ±0.44m in X, ±0.51m in Y, and ±1.82m in Z directions have been reached in spite of the very narrow angle of convergence by bias corrected RPC orientation. The image quality was also investigated with respect to effective resolution, Signal to Noise Ratio (SNR) and blur coefficient. The effective resolution was estimated with factor slightly below 1.0, meaning that the image quality corresponds to the nominal resolution of 50cm. The blur coefficients were achieved between 0.39-0.46 for triplet panchromatic images, indicating a satisfying image quality. SNR is in the range of other comparable space borne images which may be caused by de-noising of Pléiades images. The pansharpened images were generated by various methods, and are validated by most common statistical metrics and also visual interpretation. The generated DSM and DTM were achieved with ±1.6m standard deviation in Z (SZ) in relation to a reference DTM.Airbus Defence and SpaceBEU/2014-47912266-01TÜBİTAK/114Y38

A nonlinear updating algorithm captures suboptimal inference in the presence of signal-dependent noise

Bayesian models have advanced the idea that humans combine prior beliefs and sensory observations to optimize behavior. How the brain implements Bayes-optimal inference, however, remains poorly understood. Simple behavioral tasks suggest that the brain can flexibly represent probability distributions. An alternative view is that the brain relies on simple algorithms that can implement Bayes-optimal behavior only when the computational demands are low. To distinguish between these alternatives, we devised a task in which Bayes-optimal performance could not be matched by simple algorithms. We asked subjects to estimate and reproduce a time interval by combining prior information with one or two sequential measurements. In the domain of time, measurement noise increases with duration. This property takes the integration of multiple measurements beyond the reach of simple algorithms. We found that subjects were able to update their estimates using the second measurement but their performance was suboptimal, suggesting that they were unable to update full probability distributions. Instead, subjects’ behavior was consistent with an algorithm that predicts upcoming sensory signals, and applies a nonlinear function to errors in prediction to update estimates. These results indicate that the inference strategies employed by humans may deviate from Bayes-optimal integration when the computational demands are high

Imaging of subsurface lineaments in the southwestern part of the Thrace Basin from gravity data

Linear anomalies, as an indicator of the structural features of some geological bodies, are very important for the interpretation of gravity and magnetic data. In this study, an image processing technique known as the Hough transform (HT) algorithm is described for determining invisible boundaries and extensions in gravity anomaly maps. The Hough function implements the Hough transform used to extract straight lines or circles within two-dimensional potential field images. It is defined as image and Hough space. In the Hough domain, this function transforms each nonzero point in the parameter domain to a sinusoid. In the image space, each point in the Hough space is transformed to a straight line or circle. Lineaments are depicted from these straight lines which are transformed in the image domain. An application of the Hough transform to the Bouguer anomaly map of the southwestern part of the Thrace Basin, NW Turkey, shows the effectiveness of the proposed approach. Based on geological data and gravity data, the structural features in the southwestern part of the Thrace Basin are investigated by applying the proposed approach and the Blakely and Simpson method. Lineaments identified by these approaches are generally in good accordance with previously-mapped surface faults

Effects of 2,4-Diamin on some parameters of protein and carbohydrate metabolisms in the serum, muscle and liver of Cyprinus carpio

The acute and chronic effects of 2,4-Diamin, which is a widely used herbicide, were investigated in freshwater fish, Cyprinus carpio (L.). The fish were exposed to 50 and 80 ppm sublethal concentrations of the herbicide for 1, 2, 3, 4, 15, and 30 days. Various changes in protein and carbohydrate metabolisms in the serum, muscle and liver tissues were determined photometrically. Both concentrations of 2,4-Diamin inhibited glutamate-oxaloacetate transaminase activity in 30-days treatment and glutamate-pyruvate transaminase activity on 2-days treatment in the serum. The results showed an increase in lactate dehydrogenase activity at 1-day exposure to 50 ppm 2,4-Diamin, while it was at control level on the other days. There was no change in all periods after exposure to 80 ppm 2,4-Diamin concentration. Exposure to herbicide did not alter the activities of alkaline phosphatase and acid phosphatase. The effect of herbicide caused an increase in protein level in the liver in order to compensate for any possible protein loss. There was a reduction in muscle and liver glycogen levels, but serum glucose level was higher in herbicide-exposed fish than in control fish. The results in the carbohydrate metabolism suggest that an increase in the rate of glycogenolysis in the tissues of fish could be because of the stress caused by the herbicide. Copyright (C) 1999 Elsevier Science Ltd.University Grants CommissionWe are grateful to The State Hydrolic Works (DSİ) for providing fish and we wish to thank also Dr M. Canlı for his valuable help. This work was supported by a grant from The University Grants Commission (The University of Çukurova, No. FBE.93-10)

Combined effects of 2,4-D and azinphosmethyl on antioxidant enzymes and lipid peroxidation in liver of Oreochromis niloticus

PubMedID: 11246500This study aims to investigate the effects of the herbicide 2,4-D and the insecticide azinphosmethyl on hepatic antioxidant enzyme activities and lipid peroxidation in tilapia. Fish were exposed to 27 ppm 2,4-D, 0.03 ppm azinphosmethyl and to a mixture of both for 24, 48, 72 and 96 h. Activities of catalase (EC 1.11.1.6), glutathione-S-transferase (GST, EC 2.5.1.18) and the level of malondialdehyde (MDA) in the liver of Oreochromis niloticus exposed to 2,4-D and azinphosmethyl, both individually and in combination, were not affected by the pesticide exposures. However, glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) and glutathione reductase (GR, EC 1.6.4.2) activities in individual and combined treatments, increased significantly compared to controls. Furthermore, glutathione peroxidase (GPx, EC 1.11.1.9) activity increased in individual treatment, while the same enzyme activity decreased in combination. 2,4-D did not affect the activity of superoxide dismutase (SOD, EC 1.15.1.1), but the activity of this enzyme in azinphosmethyl treatment decreased, while its activity increased in combination. Combined treatment of the pesticides exerted synergistic effects in the activity of SOD, while antagonistic effects were found in the activities of G6PD, GPx, GR. The results indicate that O. niloticus resisted oxidative stress by antioxidant mechanisms and prevented increases in lipid peroxidation. (C) 2000 Elsevier Science Inc.University Grants CommissionWe thank Professor Dr Levent Kayrin for his valuable help. We are also greatful to Dr Nazmi Tekelioglu for providing fish. This work was supported by grant from The University Grant Commission (The University of Çukurova, No. FBE. 96-166)

Effects of azinphosmethyl on some biochemical parameters in blood, muscle, and liver tissues of Cypyrinus carpio (L.)

In the present study, the effects of 0.20 and 0.35 ppm azinphosmethyl exposures occurring on days 1, 2, 3, 4, and 15 for on serum enzyme activities and protein and glucose levels in blood, muscle, and liver tissues of fish, Cyprinus carpio (L.), were photometrically investigated. Protein and glycogen contents in muscle and liver tissues were also determined. Azinphosmethyl did not affect the level of total protein in serum. However, there was a decrease in the level of muscle protein in 2 days of treatment while the liver protein elevated after acute exposure to both concentration of azinphosmethyl. It was also found that there was an elevation in the serum glucose content while the muscle and liver glycogen contents were reduced. Serum enzyme activities were also altered. Glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase activities initially increased following exposure to both concentrations of azinphosmethyl; later there was no change in the activities of these enzymes. Lactate dehydrogenase enzyme activity also increased in the beginning of the experiment, but it was at the control level in 15 days. Alkaline phosphatase enzyme activity decreased on the first of day treatment while it increased second day. However, there was no significant difference during the other exposure times. After acute exposure to 0.35 ppm concentration of azinphosmethyl there was a significant increase in acid phosphatase activity while there was no change in this enzyme activity at the other exposure concentration and periods. Furthermore, sublethal concentrations of azinphosmethyl caused the behavioral and morphological changes in C. carpio. The results of this study showed that tissue necrosis and an elevation of glycogenolysis occurred following acute exposure to azinphosmethyl, but compensatory mechanisms were developed by C. carpio during chronic exposure.University Grants CommissionThis work was supported by grant from The University Grant Commission (The University of C¸ ukurova, No. FBE.93-10). We are grateful to The State Hydrolic Works (DSI) for providing the fish and also we wish to thank Dr. M. Canlı for his help

Marker enzyme assesment in the liver of Cyprinus carpio (L.) exposed to 2,4-D and azinphosmethyl

PubMedID: 12242687The potential utility of antioxidant enzymes and lipid peroxidation as indicators of exposure to 2,4-D and azinphosmethyl together with the toxic effects of these compounds in freshwater fish Cyprinus carpio were evaluated. Biochemical parameters were recorded spectrophotometrically in fish liver, which were exposed to a single dose of 2,4-D and azinphosmehtyl (1/3 LC50), and their mixture at 1:1 ratio for 24, 48, 72, and 96 h. The most sensitive parameter was glutathione S-transferase (GST) activity, which significantly increased with experimental exposures. Glucose 6-phosphate dehydrogenase activity did not change after 24 and 48 h while there was an elevation after 72 h in all exposure groups. The activity decreased only when these were applied in combination at 96 h. Superoxide dismutase activity increased after azinphosmethyl exposure for 48 and 96 h. 2,4-D decreased the activity after 24 h while the activity remained at the same level with control after 48 h. An elevation was found between 72 and 96 h. Mixture treatment did not changed the activity. Glutathione reductase and catalase enzyme activities, and malondialdehyde levels remained constant in all the treatment groups compared with controls. These results suggest that induction of GST activity may be used as biomarker for the assesment of water pollution in C. carpio. © 2002 Wiley Periodicals, Inc. J Biochem. Mol Toxicol

Acute pancreatitis due to primary hyperparathyroidism: A case report

Hyperparathyroidism and hypercalcemia are considered to be a rare cause of acute pancreatitis. The relationship between hyperparathyroidism and pancreatic inflammatory disease remains controversial, but it may be related to the translation of inactive trypsinogen to active one by hypercalcemia. We present a case of acute pancreatitis with persistently elevated serum calcium level and resistant to medical treatment. Parathyroid adenoma was diagnosed as the cause of hyperparathyroidism Following surgical resection of parathyroid adenoma, the function of pancreas and serum calcium levels returned to normal. This case might show a relationship between hyperparathyroidism and acute pancreatitis. In the management of these cases, treatment of hyperparathyroidism should be considered initially