Browsing by Author "Soto, A."

Now showing 1 - 13 of 13
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    Action Recognition in Video Using Sparse Coding and Relative Features
    (2016) Alfaro, A.; Mery Quiroz, Domingo Arturo; Soto, A.
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    Automatic selection and detection of visual landmarks using multiple segmentations
    (2006) Langdon, D.; Soto, A.; Mery Quiroz, Domingo Arturo
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    Comparing neural and attractiveness-based visual features for artwork recommendation
    (2017) Dominguez, V.; Messina, P.; Parra, D.; Mery Quiroz, Domingo Arturo; Trattner, C.; Soto, A.
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    Exploring content-based artwork recommendation with metadata and visual features
    (2017) Messina, P.; Dominguez, V.; Parra Santander, Denis Alejandro; Trattner, C.; Soto, A.
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    Fruit Firmness and Fruit Retention Strength in Raspberry Cultivars in Chile
    (2002) Bañados Ortiz, Maria Pilar; Zoffoli Guerra, Juan Pablo; Soto, A.; González, J.; Brennan, R. M.; Gordon, S. L.; Williamson, B.
    Raspberries have a short shelf life, which limits their fresh market potential. Fruit firmness is one of the most important characteristics for a fresh market cultivar, which is related to both the stage of maturity and the variety itself. Fruit retention strength define as the tension force needed to remove the receptacle from the fruit, decreases as fruit mature, and it is also cultivar dependent. The objectives of this work were to evaluate fruit firmness and fruit retention strength in 14 raspberry cultivars in Chile, and also to examine some morphological changes that occur during the fresh-frozen-thaw cycles fruits at the cellular level. To do these fresh berries were harvested at 3 different maturity stages: pink-red, red-ripe and over-ripe (processing ripe). Fruit firmness was measured using a Texture Expert TA-XT2 with a 2 mm embol. Fruit strength was measured with an adaptation of a Dindometer, an instrument that registers the tension force needed to remove the receptacle from the fruit. Electron microscopy was used to examine changes at cellular level between fresh and freeze-thaw berries in three cultivars. We found that in all 14 cultivars fruit firmness decreased with maturity. The largest differences in fruit firmness among cultivars were established at early stages of maturity. The firmest cultivar at pink-red stage was 'Chilliwack' (1.23 N), followed by 'Tulameen' (0.91 N), 'Heritage' (0.73 N) and 'Skeena' (0.68 N). 'Autumn Bliss' was the softest cultivar (0.24 N). Fruit strength also decreased as fruit matured in all 14 cultivars. In this case larger differences among them were also established at pink-red stage. 'Amity' (6.9 N) and 'Fallgold' (6.22 N) required higher amounts of force to remove the receptacle, producing in many cases broken fruits with missing drupelets. 'Yellow Meeker' (1.61 N) and 'Heritage' (2.12 N) had the lowest retention force, and therefore are the easiest cultivars to pick at early stages of maturity. Cellular dehydration was observed in 'Tulameen' after a freeze-thaw cycle. 'Heritage' showed cell dehydration and partial damaged on its epidermis. In 'Amity' a general plasmolysis was observed after a freeze-thaw cycle. Fruit firmness was not necessarily associated with morphological changes of individually quick frozen (IQF) berries. There are probably some physical characteristics of the epidermis of the fruit in the different cultivars that make some cultivars more susceptible to damage during the freeze-thaw process.
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    Human action recognition from interoral dictionaries of key-sequences
    (2014) Alfaro, A.; Mery Quiroz, Domingo Arturo; Soto, A.
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    PT symmetric fermionic field theories with axions: Renormalization and dynamical mass generation
    (2022) Mavromatos, N. E.; Sarkar, Sarben; Soto, A.
    We consider the renormalization properties of non-Hermitian Yukawa theories involving a pseudoscalar (axion) field at or near four dimensions. The non-Hermiticity is PT symmetric where P is a linear operator (such as parity) and T is an antilinear idempotent operator (such as time reversal). The coupling constants of the Yukawa and quartic scalar coupling terms reflect this non-Hermiticity. The path integral representing the field theory is used to discuss the Feynman rules associated with the field theory. The fixed point structure associated with the renormalization group has PT symmetric and Hermitian fixed points. At two loops in the massless theory, we demonstrate the flow from Hermitian to non-Hermitian fixed points. From the one-loop renormalization of a massive Yukawa theory, a self-consistent Nambu-Jona-Lasinio gap equation is established and its real solutions are discussed.
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    Indoor scene recognition through object detection
    (IEEE, 2010) Espinace Ronda, Pablo Andrés; Kollar, T.; Soto, A.; Roy, N.
    Scene recognition is a highly valuable perceptual ability for an indoor mobile robot, however, current approaches for scene recognition present a significant drop in performance for the case of indoor scenes. We believe that this can be explained by the high appearance variability of indoor environments. This stresses the need to include high-level semantic information in the recognition process. In this work we propose a new approach for indoor scene recognition based on a generative probabilistic hierarchical model that uses common objects as an intermediate semantic representation. Under this model, we use object classifiers to associate low-level visual features to objects, and at the same time, we use contextual relations to associate objects to scenes. As a further contribution, we improve the performance of current state-of-the-art category-level object classifiers by including geometrical information obtained from a 3D range sensor that facilitates the implementation of a focus of attention mechanism within a Monte Carlo sampling scheme. We test our approach using real data, showing significant advantages with respect to previous state-of-the-art methods.
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    Induced Maxwell-Chern-Simons effective action in very special relativity
    (2020) Bufalo, R.; Ghasemkhani, M.; Haghgouyan, Z.; Soto, A.
    In this paper, we study the one-loop induced photon's effective action in the very special relativity electrodynamics in (2+1) spacetime (VSR-QED3). Due to the presence of new nonlocal couplings resulting from the VSR gauge symmetry, we have additional graphs contributing to the AA and AAA amplitudes. From these contributions, we discuss the VSR generalization of the Abelian Maxwell-Chern-Simons Lagrangian, consisting in the dynamical part and the Chern-Simons-like self-couplings, respectively. We use the VSR-Chern-Simons electrodynamics to discuss some non-Ohmic behavior on topological materials, in particular VSR effects on Hall's conductivity. In the dynamical part of the effective action, we observe the presence of a UV/IR mixing, due to the entanglement of the VSR nonlocal effects to the quantum higher-derivative terms. Furthermore, in the self-coupling aspect, we verify the validity of the Furry's theorem in the VSR-QED3 explicitly.
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    Joint dictionary and classifier learning for categorization of images using a max-margin framework
    (2014) Lobel, H.; Vidal, R.; Mery Quiroz, Domingo Arturo; Soto, A.
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    Learning discriminative local binary patterns for face recognition
    (2011) Maturana, D.; Mery Quiroz, Domingo Arturo; Soto, A.
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    Towards improving Top-N recommendation by generalization of SLIM
    (2015) Larraín, S.; Parra Santander, Denis Alejandro; Soto, A.