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The purpose of this study is to analyze the temporal dynamics of the free surface area of shallow lakes during the period 1984–2015 in the Pampas region, Argentina, using satellite image processing (Landsat 4 TM, Landsat 5 TM, Landsat 7 ETM+ and Landsat 8 OLI). The evolution of the free surface of five shallow lakes in two distinct basins of the province of Buenos Aires can be explained using generalized linear models (GLM) and taking as explanatory variables the accumulated precipitation and the number of rainfall days over a given period before the acquisition date of the satellite image. Accumulated precipitation and frequency of days with precipitation were calculated for 1, 7, 30, 90, and 180 days, as well as for 1, 2, 3, and 4 years, respectively. The results show that the explanatory variables linked to the memory of the system (3 and 4 years) contribute significantly in all cases to the reconstruction of the areas. In particular, long-term variables reconstruct accurately (R2 between 0.76 and 0.91) the area of the five shallow lakes for the period 2001–2015. The short-term explanatory variables (7 and 30 days) are also significant to the reconstruction of the variations observed in the first period (1984–2000) but only for the two lakes in the Southeastern basin (R2 = 0.70 and 0.94), while in the Center-South upper basin, only one of the lakes exhibits some short-term dependency in the second period (2001–2015) (R2 = 0.83). [ABSTRACT FROM AUTHOR]

In this article, a method is presented for automatic scaling of the F-layer from ionograms based on an image processing technique for the extraction of curvilinear structures. The algorithm obtains the ordinary and extraordinary traces and determines the F2 critical frequency. The performance was tested using a wide data set of ionograms recorded by the Advanced Ionospheric Sounder/Istituto Nazionale di Geofisica e Vulcanologia (AIS/INGV) ionosonde located at Universidad Nacional de Tucumán, Tucuman, Argentina, and the results are compared with manual scaling and also with Autoscala method. Results from these tests show that the method is feasible and can be the seed for the development of a robust automated scaling system. [ABSTRACT FROM AUTHOR]

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This work presents a novel way of measuring image-based migration velocity and dune length in clear water rivers. These results, together with empirical formulations, can be used to estimate bedload sediment transport with a high-spatial resolution. Image processing relies on the non-intrusive image-based technique called Space-Time Image Velocimetry (STIV). STIV consists in visualizing pixel intensity variation in time over a defined line. This technique was originally applied to hydraulics in order to characterize streamwise surface velocities in rivers. In this case, STIV is used to measure dune migration velocity and length in a shallow river with clear water in Córdoba Province, Argentina. Image processing procedures are detailed, including pre-processing and rectification. Results are then compared with measurements obtained from Acoustic Doppler Current Profilers. Finally, as an appendix, using the measured data and empirical equations, an estimation of bedload sediment transport is performed using both techniques. • STIV technique allows for an estimation of the mean streamwise migration velocity of sand dunes in clear water flow conditions. • The use of image processing provides accurate estimates of average dune length. • Results obtained from images are compared with results from ADCP. • Bed load sediment transport can be quantified from Space/Time Images and an empirical approach. [ABSTRACT FROM AUTHOR]

Abstract: The problem of automatic number plate recognition (ANPR) has been studied from different aspects since the early 90s. Efficient approaches have been recently developed, particularly based on the features of the license plate representation used in different countries. This paper focuses on a novel approach to solving the ANPR problem for Argentinean license plates, called Intelligent Template Matching (ITM). We compare the performance obtained with other competitive approaches to robust pattern recognition (such as artificial neural networks), showing the advantages both in classification accuracy and training time. The approach can also be easily extended to other license plate representation systems different from the one used in Argentina. [Copyright &y& Elsevier]

SUMMARY Multichannel reflection seismic profiles, combined with gravimetric and magnetic data provide insight into the crustal structure of the southernmost Argentine margin, at the transition from a rifted to a transform margin and outline the extent of the North Falkland Graben. Based on these data, we establish a regional stratigraphic model for the post-rift sediments, comprising six marker horizons with a new formation in the Barremian/Lower Cretaceous. Our observations support that a N-S trending subsidiary branch of the North Falkland Graben continues along the continental shelf and slope to the Argentine basin. During the rift phase, a wide shelf area was affected by the E-W extension, subsequently forming the North Falkland Graben and the subsidiary branch along which finally breakup occurred. We propose the division of the margin in two segments: a N-S trending rifted margin and an E-W trending transform margin. This is further underpinned by crustal scale gravity modelling. Three different tectono-dynamic processes shaped the study area. (1) The Triassic/Early Jurassic extensional phase resulting in the formation of the North Falkland Graben and additional narrower rift grabens ended synchronously with the breakup of the South Atlantic in the early Valanginian. (2) Extensional phase related to the opening of the South Atlantic. (3) The transform margin was active in the study area from about Hauterivian times and activity lasted until late Cretaceous/early Cenozoic. Both, the rifted margin and the transform margin are magma-poor. Very limited structures may have a volcanic origin but are suggested to be post-rift. The oceanic crust was found to be unusually thin, indicating a deficit in magma supply during formation. These findings in combination with the proposed breakup age in the early Valanginian that considerably predates the formation of the Paraná-Etendeka continental flood basalt provinces in Brazil and Namibia question the influence of the Tristan da Cunha hotspot during the initial formation of the South Atlantic. [ABSTRACT FROM AUTHOR]

Abstract: Scanning electron microscopy is a powerful technique in several fields of science and technology. In particular it is an important complement in the characterization of materials for which X-ray analysis is not possible. Such is the case of thin paint layers on ceramic pots, in which, even for low incident energies, the electron interaction volume can be greater than the paint thickness—in addition to the problem arising from similar compositions. With the aim of complementing other common techniques used in compositional materials characterization, in this work, an image-processing software has been developed, which implements a new methodology for the treatment of backscattered electron (BSE) images in order to bring to evidence small mean atomic number contrasts, usually imperceptible to human eye. The program was used to study black and white pigments of ceramic pieces belonging to the Ambato style of “Aguada” culture (Catamarca province, Argentina, IV–XII centuries AD). Although the BSE images acquired for these samples showed no apparent contrast between sherd and black and white pigments, through image-processing algorithms using different space filters, chemical contrast between regions has been brought to evidence with a minor detail loss. This has been accomplished by applying a smoothing filter, after which the main routine for contrast enhancement reveals details in the grey-level region of interest; finally, a filter for edge enhancement permits to recover some details lost in the previous steps, achieving satisfactory results for the painted sherd samples analyzed. In order to validate the mean atomic number differences found between each pigment and the ceramic body, X-ray diffraction diagrams have been refined with Rietveld method using the software DIFFRACplus Topas®, arriving to mineralogical differences which agree with the results obtained. As a consequence of this study, the program developed has proven to be a suitable tool for routine analysis of samples with slight chemical contrast. [Copyright &y& Elsevier]

In this work we studied the activity of four long period comets at different heliocentric distances in order to explore their dust production and characteristics. The targets were the comets C/2011 A3 (Gibbs), C/2012 K1 (PanStarrs), C/2012 LP26 (Palomar) and C/2013 F3 (McNaught). Some of these objects have never been studied before. We analyzed images in V and R filters taken with the 2.15 ​m telescope at Complejo Astronómico El Leoncito (CASLEO), Argentina, to characterize their dust coma features and to investigate the morphology, photometry and dust production. The morphological analysis showed some differences among the sample while the Afρ values measured in a reference aperture of radius ρ ​= ​104 ​km showed a scenario of bodies that fit the profile of a long period comet. This is corroborated by the Minor Planet Center dynamical classification. • We studied the activity of four long period comets in their post-perihelion arc. • The comets are C/2011 A3-Gibbs, C/2012 K1-PanStarrs, C/2012 LP26-Palomar and C/2013 F3-McNaught • We analyzed images in V and R filters to characterize their dust coma features and to investigate the morphology, photometry and Af ρ value. [ABSTRACT FROM AUTHOR]

Automatic mapping techniques using multiband satellite image information have been used to study sediment grain-size variations on an alluvial bajada. A previous study of sparsely vegetated alluvial surfaces in central-western Argentina showed that the reflectivity recorded in seven-band Landsat TM images is controlled by sediment composition, age and grain size. At diameters >4 mm, clast composition influences image information, while at grain sizes smaller than sand, clay mineralogy begins to influence spectral characteristics. The progressive increase in desert varnish and the loss of fine grain-size fractions as a result of deflation cause the age influence. The bajada sedimentary environment is well suited for testing the influence of grain-size variability on image recovery, as most drainage basins are small and sourced by a single geological unit, which produces compositionally homogeneous alluvial surfaces. Additionally, most drainage lines are active within intervals of 10–50 years, reducing the effect of surface ageing. Larger than average drainage basins produce oversized drainage lines that disrupt the bajada, generate individual alluvial fans and have slightly different compositions. Two typical bajadas were selected to map grain-size characteristics using automatic classification techniques. The obtained classes were checked in the field, and grain-size and compositional counts were completed. Although both bajadas are very different in composition, most grain-size curves showed similar shapes, suggesting that deposition took place by the same process (hyperconcentrated flash floods). The values of the median and mean were consistent across the same class between both bajadas. Thus, unsupervised classification techniques are useful for mapping sediment grain size, although minor field control is needed. Image classes represent areas of similar grain size, which are elongated parallel to the mountain front in an active alluvial bajada, indicating a homogeneous distribution of sedimentary processes along strike. Changes in the width of image classes indicate different downstream fining rates closely related to the topographic gap and the slope change rate. In contrast to bajadas, alluvial fans have semi-circular belts and a pie-piece-shaped area in which most active streams are located. Thus, unlike fans, bajadas lack autocyclic mechanisms for producing heterogeneous sedimentary sequences. The sedimentary log of an ancient bajada was measured in order to show the influence of allocyclic factors in the absence of autocyclicity. [ABSTRACT FROM AUTHOR]

In this work we studied the activity of a group of long and short period comets at different heliocentric distances in order to explore and compare their dust production and characteristics. The targets observed were the comets 22P/Kopff, 29P/Schwassmann-Wachmann 1, 218P/LINEAR, 221P/LINEAR, 318P/McNaught-Hartley, C/2010 FB87 (WISE-Garradd), C/2010 G2 (Hill), C/2011 KP36, C/2011 L4 (PANSTARRS) and C/2013 US10 (Catalina). Several of these objects have never been studied before. We analyzed images in V and R filters taken with the 2.15 m telescope at Complejo Astronómico El Leoncito (CASLEO), Argentina, to characterize their dust coma features and to investigate the morphology, photometry and dust production. The morphological analysis shown many differences among the sample of objects observed, showing several structures from the large twisted regions to collimated jets that do not follow the anti-solar direction. The Afρ values measured in a reference aperture of radius ρ = 10 4 k m shown a scenario of bodies ranging from dust poor to very active ones. This is confirmed by the quantitative estimate of the dust mass-loss rate obtained from the photometric data. • We studied the activity of a group of long and short period comets. • The SP comets are 22P/Kopff, 29P/Schwassmann-Wachmann 1, 218P/LINEAR, 221P/LINEAR and 318P/McNaught-Hartley. • The LP comets are C/2010 FB87 (WISE-Garradd), C/2010 G2 (Hill), C/2011 KP36, C/2011 L4 (PANSTARRS) and C/2013 US10 (Catalina). • We analyzed images in V and R filters to investigate the morphology, photometry and dust production. [ABSTRACT FROM AUTHOR]