A contour matching approach for accurate NOAA-AVHRR image navigation

Although different methods for NOAA AVHRR image navigation have already been established, the multitemporal and multi-satellite character of most studies requires automatic and accurate methods for navigation of satellite images. In the proposed method, a simple Kepplerian orbital model for the NOAA satellites is considered as reference model, and mean orbital elements are given as input to the model from ephemeris data. In order to correct the errors caused by these simplifications, errors resulting from inaccuracies in the positioning of the satellite and failures in the satellite internal clock, an automatic global contour matching approach has been adopted. First, the sensed image is preprocessed to obtain a gradient energy map of the reliable areas (sea-land contours) using a cloud detection algorithm and a morphological gradient operator. An initial estimation of the reliable contour positions is automatically obtained. The final positions of the contours are obtained by means of an iterative local minimization procedure that allows a contour to converge on an area of high image energy (edge). Global transformation parameters are estimated based on the initial and final positions of all reliable contour points. Finally, the performance of this approach is assessed using NOAA 14 AVHRR images from different geographic areas.Postprint (published version

A counterexample for H ∞ approximable functions

Let D be the unit disk. We show that for some relatively closed set F ⊂ D there is a function f that can be uniformly approximated on F by functions of H∞, but such that f cannot be written as f = h + g, with h ∈ H∞ and g uniformly continuous on F. This answers a question of Stray.Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Approximation and the n-Berezin transform of operators on the Bergman space

To any bounded operator S on the Bergman space La2 we associate a sequence of linear transforms Bn(S ) ∈ L∞(D), where n ≧ 0, and prove that the Toeplitz operators article image tend to S for some especial classes of operators S. In particular, this holds for every radial operator in the Toeplitz algebra. Finally, we show that the inclusion of the Toeplitz algebra into the essential commutant of the Bergman shift is proper.Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina. Universitat Autònoma de Barcelona; Españ

Localisation techniques for division in Douglas algebras

In this paper we use uniform algebra techniques and recent results on separation properties to prove several division theorems for closed subalgebras of L∞ containing H∞. We also study ideals having the local approximation property and we show that not every ideal in such algebras is local.Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

The Toeplitz algebra on the Bergman space coincides with its commutator ideal

Let L^2-a be the Bergman space of the unit disk and T(L^2_a) be the Banach algebra generated by Toeplitz operators T_f , with f ∈ L∞. We prove that the closed bilateral ideal of T(L2a) generated by operators of the form T_fT_g − T_gT_f coincides with T(L^2_a).Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Identification and Characterization of the Lipid Transport System in the Tarantula Grammostola rosea

Lipids due to its hydrophobic nature are transported in the hemolymph mainly by lipoproteic fractions. In the present work we studied the lipoproteic fractions present in the hemolymph of the spider Grammostola rosea. Through ultracentrifugation two lipoproteic fractions are isolated, one of high density named Gr-HDL (δ = 1.13 - 1.15 g/ml) and the other of very high density called Gr-VHDL (δ = 1.24 - 1.27 g/ml) Gr-VHDL in hemolymph is majority in relation to Gr-HDL. In this sense Gr-VHDL fraction has 98.6% of hemolymphatic proteins, and 89.3% of lipids presents in the hemolymph. Both lipoproteic fractions possess phospholipids such as majority lipids (phosphatidylcholine and phosphatidylethanolamine) and 18:1, 16:0, 18:2 and 18:0 as the major fatty acids. In order to confirm the role played by lipoproteic fractions in vitro assays with different 14C-lipid were performed. It was observed that Gr-VHDL takes up mainly free fatty acids and triacylglycerols unlike that observed for Gr-HDL in relation to phosphatidylcholine. Through electrophoresis it was observed that Gr-VHDL has three proteins: a predominant band of 68 kDa and two others of 99 and 121 kDa. Gr-HDL displayed a predominant band of 93 kDa, and other minority of 249 kDa. In conclusion, this study reports lipid characterization of the lipoproteic fractions present in the hemolymph of the tarantula, G. rosea. The role of each lipoproteic fraction in relation to lipid up- take is sustained by in vitro assays. Similarities and differences are found when it is compared to lipoproteins of only the three species of spiders studied.Fil: Laino, Aldana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Cunningham, Monica Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Suarez, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Garcia, Carlos Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; Argentin

Accurate and automatic NOAA-AVHRR image navigation using a global contour matching approach

The problem of precise and automatic AVHRR image navigation is tractable in theory, but has proved to be somewhat difficult in practice. The authors' work has been motivated by the need for a fully automatic and operational navigation system capable of geo-referencing NOAA-AVHRR images with high accuracy and without operator supervision. The proposed method is based on the simultaneous use of an orbital model and a contour matching approach. This last process, relying on an affine transformation model, is used to correct the errors caused by inaccuracies in orbit modeling, nonzero value for the spacecraft's roll, pitch and yaw, errors due to inaccuracies in the satellite positioning and failures in the satellite internal clock. The automatic global contour matching process is summarized as follows: i) Estimation of the gradient energy map (edges) in the sensed image and detection of the cloudless (reliable) areas in this map. ii) Initialization of the affine model parameters by minimizing the Euclidean distance between the reference and sensed images objects. iii) Simultaneous optimization of all reference image contours on the sensed image by energy minimization in the domain of the global transformation parameters. The process is iterated in a hierarchical way, reducing the parameter searching space at each iteration. The proposed image navigation algorithm has proved to be capable of geo-referencing a satellite image within 1 pixel.Peer ReviewedPostprint (published version

ELT novice and experienced teachers’ teaching strategies for enhancing speaking skill

"This study aims to explore the teaching strategies that novice and experienced teachers use to enhance students’ speaking skills in the classroom. This research project analyzes the similarities and differences between the strategies that these teachers use to make the teaching-learning process more efficient. The research questions that guided this study are 1) What strategies do novice teachers use the most to enhance students’ speaking skills? 2) What strategies do experienced teachers use the most to enhance students' speaking skills? and 3) What are the differences between experienced and novice strategies to enhance students' speaking skills? In addition, this study adopts a Mixed-method approach. The study was conducted with thirty English language teachers from public and private universities in the city of Puebla. To collect data for this study the instrument used was a questionnaire. The data was analyzed, and the findings showed that both novice and experienced teachers employ different strategies for enhancing students’ oral skills. Most of the strategies these teachers use in their English classes follow a student-centered approach. It was also observed that these strategies require limited intervention from the teacher"