Prototypicality effects in global semantic description of objects

In this paper, we introduce a novel approach for semantic description of object features based on the prototypicality effects of the Prototype Theory. Our prototype-based description model encodes and stores the semantic meaning of an object, while describing its features using the semantic prototype computed by CNN-classifications models. Our method uses semantic prototypes to create discriminative descriptor signatures that describe an object highlighting its most distinctive features within the category. Our experiments show that: i) our descriptor preserves the semantic information used by the CNN-models in classification tasks; ii) our distance metric can be used as the object's typicality score; iii) our descriptor signatures are semantically interpretable and enables the simulation of the prototypical organization of objects within a category.Comment: Paper accepted in IEEE Winter Conference on Applications of Computer Vision 2019 (WACV2019). Content: 10 pages (8 + 2 reference) with 7 figure

Two new species of Microcotyle (Monogenea: Microcotylidae) on intertidal fish from the south Pacific coast

Microcotyle is one of the most diverse and controversial genera within the family Microcotylidae. To date, 131 species have been described in Microcotyle; however, more than half have been transferred to other genera, and several others have poor descriptions. Therefore, less than half of all Microcotyle species may be considered valid. In Chile, two species have been recognized, and unidentified Microcotyle have been found on several littoral fish, but there has been no effort to properly identify them. In this study, two new species of Microcotyle are taxonomically described from intertidal fish of the central (33°S) and south-central (36°S) regions of Chile. In this study, Microcotyle sprostonae n. sp. (collected mainly from Scartichthys viridis in central Chile) and M. chilensis n. sp. (collected mainly from Calliclinus geniguttatus in south-central Chile) were identified based on morphological and molecular analyses (ITS2 and 18S genes). Both species of Microcotyle principally differed from one another and from other valid species in the number of testes and clamps. The two new species also differed from one another by one base pair in the ITS2 and 18S genes and differed from other species of Microcotyle by several base pairs of both genes. Intertidal fish are mostly endemic to the Pacific coast of South America, and they have a limited geographical distribution that does not overlap with the type hosts of other Microcotyle species. Therefore, the two new species described here are distinguished from other congeneric species by morphological, genetic, and biological characteristics

Efficient Computation of Multiple Density-Based Clustering Hierarchies

HDBSCAN*, a state-of-the-art density-based hierarchical clustering method, produces a hierarchical organization of clusters in a dataset w.r.t. a parameter mpts. While the performance of HDBSCAN* is robust w.r.t. mpts in the sense that a small change in mpts typically leads to only a small or no change in the clustering structure, choosing a "good" mpts value can be challenging: depending on the data distribution, a high or low value for mpts may be more appropriate, and certain data clusters may reveal themselves at different values of mpts. To explore results for a range of mpts values, however, one has to run HDBSCAN* for each value in the range independently, which is computationally inefficient. In this paper, we propose an efficient approach to compute all HDBSCAN* hierarchies for a range of mpts values by replacing the graph used by HDBSCAN* with a much smaller graph that is guaranteed to contain the required information. An extensive experimental evaluation shows that with our approach one can obtain over one hundred hierarchies for the computational cost equivalent to running HDBSCAN* about 2 times.Comment: A short version of this paper appears at IEEE ICDM 2017. Corrected typos. Revised abstrac

Fast-Forward Video Based on Semantic Extraction

Thanks to the low operational cost and large storage capacity of smartphones and wearable devices, people are recording many hours of daily activities, sport actions and home videos. These videos, also known as egocentric videos, are generally long-running streams with unedited content, which make them boring and visually unpalatable, bringing up the challenge to make egocentric videos more appealing. In this work we propose a novel methodology to compose the new fast-forward video by selecting frames based on semantic information extracted from images. The experiments show that our approach outperforms the state-of-the-art as far as semantic information is concerned and that it is also able to produce videos that are more pleasant to be watched.Comment: Accepted for publication and presented in 2016 IEEE International Conference on Image Processing (ICIP

Optimal Time-dependent Sequenced Route Queries in Road Networks

In this paper we present an algorithm for optimal processing of time-dependent sequenced route queries in road networks, i.e., given a road network where the travel time over an edge is time-dependent and a given ordered list of categories of interest, we find the fastest route between an origin and destination that passes through a sequence of points of interest belonging to each of the specified categories of interest. For instance, considering a city road network at a given departure time, one can find the fastest route between one's work and his/her home, passing through a bank, a supermarket and a restaurant, in this order. The main contribution of our work is the consideration of the time dependency of the network, a realistic characteristic of urban road networks, which has not been considered previously when addressing the optimal sequenced route query. Our approach uses the A* search paradigm that is equipped with an admissible heuristic function, thus guaranteed to yield the optimal solution, along with a pruning scheme for further reducing the search space. In order to compare our proposal we extended a previously proposed solution aimed at non-time dependent sequenced route queries, enabling it to deal with the time-dependency. Our experiments using real and synthetic data sets have shown our proposed solution to be up to two orders of magnitude faster than the temporally extended previous solution.Comment: 10 pages, 12 figures To be published as a short paper in the 23rd ACM SIGSPATIA