Papers by Ricardo Guerrero
Archiv für Hydrobiologie, 1992
Community structure in Lake Cisó: Biomass allocation to trophic groups and differing patterns of ... more Community structure in Lake Cisó: Biomass allocation to trophic groups and differing patterns of seasonal succession in the meta- and epilimnion.
Quark, 2002
H.G. Wells, científico y profesor, es conocido por sus obras de ciencia ficción y sus obras de di... more H.G. Wells, científico y profesor, es conocido por sus obras de ciencia ficción y sus obras de divulgación sobre biología. S.J. Gould, a su vez también científico y profesor, hizo posible que la ciencia además de ser comprensible pudiera ser divertida. La intención de estos autores es poner al alcance del público los conocimientos científicos. H.G. Wells, a scientist and teacher, is well-known for his works on Science Fiction and his contributions to Popularization of Biology. S.J. Gould, a scientist and teacher as well, made the possibility that Science could be understandable and funny at the same time come true. The aim of these authors was to place scientific knowledge at people reach.
International Microbiology, Feb 27, 2010
International Microbiology, Feb 28, 2010
The birth of Open Access "Open access" is the term used to describe literature that is available ... more The birth of Open Access "Open access" is the term used to describe literature that is available to any reader at no cost on the Internet. The copyright owner-usually the author-allows the user to freely read, download, copy, print, distribute, search, link to the full text of the article, crawl it for indexing, convert the reported data to software, or use the article for any other lawful purpose. In open-access journals, authors either retain copyright or are asked to transfer the copyright to the publisher. In both cases, the copyright holder must consent to open access to the articles. The only role of copyright in open-access literature is to give authors control of the integrity of their work and the right to be properly acknowledged and cited [8]. Although open access is a concept that is most often applied to online publication, it is nonetheless compatible with print for those journals that also have a printed version. Open access is free of charge for readers of the online version, but does not exclude priced access to print versions of the same work. It all started in Budapest, on December 1-2, 2001, when leading proponents of a new initiative in scientific and scholarly publication and archiving gathered under the auspices of the Open Society Institute (OSI). The OSI was founded in 1993 by the investor and philanthropist George Soros to serve his foundations, which currently have expanded to more than fifty countries. OSI and the Soros foundations aim "to promote open societies by shaping government policy and supporting education, media, public health and human and women's rights, as well as social, legal, and economic reform." The participants at the Budapest meeting, who had previous experience with the various initiatives discussed by the open-access movement, represented many organizations, scientific disciplines and countries. The objective of that meeting was to join efforts and unite the strategies of the separate initiatives into a plan of action aimed at achieving broader, deeper and more rapid success, and to determine how the resources of the OSI could be used to aid the cause of open access [1]. The primary outcome of the meeting was
Metode Revista De Difusion De La Investigacion, 2011
EPJ Techniques and Instrumentation, 2014
Los murciélagos son parasitados por diversas familias de dípteros y ácaros (Arthropoda); los cual... more Los murciélagos son parasitados por diversas familias de dípteros y ácaros (Arthropoda); los cuales son abundantes, diversos y pueden incidir sobre las poblaciones de hospedadores. En Colombia son pocos los trabajos desarrollados sobre tipo de ectoparasitismo, sin embargo investigaciones realizadas resaltan al menos 54 especies de dípteros como parásitos obligados. El Bosque Seco Tropical (Bs-T) es uno de los ecosistemas menos estudiados tanto en murciélagos como en sus ectoparásitos, por lo que se plantea desarrollar investigaciones encaminadas a identificar estas relaciones en el valle del Magdalena, norte del Tolima, una de las regiones con mayor área de Bs-T a nivel nacional. Los murciélagos fueron revisaron durante la toma de datos y los ectoparásitos aislados se depositaron en viales Eppendorf (alcohol 70%) para su determinación. Se capturó un total de 140 murciélagos distribuidos en 5 familias y 21 especies siendo la de mayor abundancia relativa e incidencia acumulada Carolli...
International microbiology : the official journal of the Spanish Society for Microbiology, 2005
Registration is a powerful tool that allows mapping images in a common space in order to aid in t... more Registration is a powerful tool that allows mapping images in a common space in order to aid in their analysis. Accurate registration of images of the knee is challenging to achieve using intensity based registration algorithms. Problems arise due to large anatomical inter-subject differences which causes registrations to fail to converge to an accurate solution. In this work we propose learning correspondences in pairs of images to match self-similarity features, that describe images in terms of their local structure rather than their intensity. We use RANSAC as a robust model estimator. We show a substantial improvement in terms of mean error and standard deviation of 2.13mm and 2.47mm over intensity based registration methods, when comparing landmark alignment error.
Medical Imaging 2013: Image Processing, 2013
The identification of anatomical landmarks in medical images is an important task in registration... more The identification of anatomical landmarks in medical images is an important task in registration and morphometry. The manual identification and labeling of these landmarks is very time consuming and prone to observer errors, especially when large datasets must be analyzed. Matching landmarks in a pair of images is a challenging task. Although off-the-shelf feature point descriptors are powerful at describing points in an image, they are generic by nature, as they have been usually developed for applications in a computer vision setting where there is little prior knowledge about the images. Leveraging on recent developments in the machine learning community, this paper aims to build feature point descriptors that are dataset-specific. The proposed approach describes landmarks as feature descriptors based on a sparse coding reconstruction of a patch surrounding the landmark (or any point of interest), using a dataset-specific learned dictionary. Since strong spatial constraints typically exist in medical images, we also combine spatial information of surrounding point descriptors into a graphical model that is built online. We show accurate results in matching one-to-one anatomical landmarks in brain MR images.
Changing the Global Environment, 1989
International microbiology : the official journal of the Spanish Society for Microbiology, 2011
The bacterial microbiota from the whole gut of soldier and worker castes of the termite Reticulit... more The bacterial microbiota from the whole gut of soldier and worker castes of the termite Reticulitermes grassei was isolated and studied. In addition, the 16S rDNA bacterial genes from gut DNA were PCR-amplified using Bacteria-selective primers, and the 16S rDNA amplicons subsequently cloned into Escherichia coli. Sequences of the cloned inserts were then used to determine closest relatives by comparison with published sequences and with sequences from our previous work. The clones were found to be affiliated with the phyla Spirochaetes, Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Synergistetes, Verrucomicrobia, and candidate phyla Termite Group 1 (TG1) and Termite Group 2 (TG2). No significant differences were observed with respect to the relative bacterial abundances between soldier and worker phylotypes. The phylotypes obtained in this study were compared with reported sequences from other termites, especially those of phylotypes related to Spirochaetes, Wolbachia (...
International Microbiology, 2002
The sulfur cycle of Ebro Delta microbial mats was studied in order to determine sulfide productio... more The sulfur cycle of Ebro Delta microbial mats was studied in order to determine sulfide production and sulfide consumption. Vertical distribution of two major functional groups involved in the sulfur cycle, anoxygenic phototrophic bacteria and dissimilatory sulfate-reducing bacteria (SRB), was also studied. The former reached up to 2.2•10 8 cfu cm-3 sediment in the purple layer, and the latter reached about 1.8•10 5 SRB cm-3 sediment in the black layer. From the changes in sulfide concentrations under light-dark cycles it can be inferred that the rate of H 2 S production was 6.2 lmol H 2 S cm-3 day-1 at 2.6 mm, and 7.6 lmol H 2 S cm-3 day-1 at 6 mm. Furthermore, sulfide consumption was also assessed, determining rates of 0.04, 0.13 and 0.005 mmol l-1 of sulfide oxidized at depths of 2.6, 3 and 6 mm, respectively.
International Microbiology, 2001
International Journal for Parasitology, 2004
FEMS Microbiology Letters, 1995
Canadian Journal of Microbiology, 1987
Ultraviolet irradiation and cyclic AMP treatment produce a synergistic effect on the induction of... more Ultraviolet irradiation and cyclic AMP treatment produce a synergistic effect on the induction of the clel gene (coding for bacteriocin ColE1) in wild-type strains of Escherichia coli. On the other hand, cyclic AMP does not affect the uv-mediated induction of the recA, sfiA, and umuDC genes. Growth in the presence of glucose or glycerol does not affect the factor of amplification of the expression of the clel gene in uv-irradiated cells of the wild-type strain. Although, in cultures not treated with uv, the basal level of clel induction is about twice as high in cells grown with glycerol as in those using glucose as carbon source. In recA mutants neither simultaneous nor separate treatments with either cyclic AMP or uv irradiation induced transcription of the clel gene. Moreover, cyclic AMP induced a slight increase in clel gene expression in uv-irradiated cya strains, but not in the crp mutants. Nevertheless, the pattern of the uv-mediated induction of other SOS genes, such as umuD...
Archives of Microbiology, 1985
Accumulation of poly-ß-hydroxybutyrate (PHB) was studied in Alcaligenes eutrophus strain N9A. Und... more Accumulation of poly-ß-hydroxybutyrate (PHB) was studied in Alcaligenes eutrophus strain N9A. Under nitrogen limitation and heterotrophic conditions, the cells accumulated PHB at a rate of 50 fg cell-1 h-1. Volume increased from 1.208 to 3.808 µm3 and buoyant density from 1.110 to 1.145 pg µm-3 with an increase in PHB from 0 up to 1.699 pg cell-1. Volume was found to change linearly with PHB content. The changes were due to increases in cell width and not in cell length. PHB explained 93% of the changes in cellular volume. The relationship between density and PHB was hyperbolic. PHB explained 96% of the changes in density. When a mutant strain unable to accumulate PHB was analyzed together with the wild type, the PHB-less mutant and the wild type showed densities of 1.100 pg µm-3 and 1.120 pg µm-3, respectively, in gradients of 65% Percoll. In sucrose gradients, nevertheless, the results were reversed. This discrepancy was explained by the high osmolarity of sucrose which gives artificial results. Thus, we conclude that Percoll is a more suitable medium than sucrose to measure the density of live bacterial cells.
En aquest treball es presenta una visió general d'allb que es coneix de la biologia de l'es-tanyo... more En aquest treball es presenta una visió general d'allb que es coneix de la biologia de l'es-tanyo1 d'en Cisó (Banyoles) desprts de tretze anys d'estudis. Es resumeix el que se sap del marc físic que representa l'estanyol, dels organismes que hi viuen, i dels processos biolbgics en qui: aquests organismes participen. Finalment, es revisa també tot el que se sap de l'ecologia de les poblacions de bacteris fototrbfics i del protist alga1 Cryptomonas phaseolus, especialment els cicles diari i anual de les dues poblacions, la competkncia per la llum entre diferents organismes, la formació i manteniment de la capa bacteriana, i l'estructuració vertical de les poblacions. RESUMEN En este trabajo se presenta una visión general de 10 que se conoce de la biologia de la laguna Cisó (Banyoles) tras trece años de estudio. Se resume todo 10 que se conoce sobre el marco fisico que es la laguna, 10s organismos que habitan en ella, y 10s procesos biológicos en que estos organismos estan involucrados. Finalmente, se revisa todo 10 que se conoce de la ecologia de las poblaciones de bacterias fototróficas y del protista alga1 Cryptomonas phaseolus, especialmente 10s ciclos diarios y anuales de las dos poblaciones, la competencia por la luz entre distintos organismos, la formación y mantenimiento de la capa bacteriana, y la estructuración vertical de las poblaciones.
International Microbiology, 2003
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Papers by Ricardo Guerrero