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How to fill the biodiversity data gap:Is it better to invest in fieldwork or curation?

Plant Diversity 2024年第1期46卷 39-48页

作者： carlos A.vargas Marius Bottin Tiina Sarkinen James E.Richardson Marcela Celis Boris Villanueva Adriana Sanchez Programa de Biología Facultad de Ciencias NaturalesUniversidad del RosarioBogotaD.C.Colombia Subdireccion Científica Jardín Botanico de Bogota“Jose Celestino Mutis”BogotaD.C.Colombia Independent Researcher BogotaD.C.Colombia Tropical Diversity Section Royal Botanic Garden EdinburghUK School of Biological Earth and Environmental SciencesUniversity College CorkCorkIreland Departamento de Química y Biología Universidad del NorteKm.5 Vía Puerto ColombiaArea Metropolitana de Barranquilla 081007Colombia

Data gaps and biases are two important issues that affect the quality of biodiversity information and downstream *** how best to fill existing gaps and account for biases is necessary to improve our current information most *** current main approaches for obtaining and improving data include(1)curation of biological collections,and(2)***,the comparative effectiveness of these approaches in improving biodiversity data remains little *** used the Flora de Bogota project to study the magnitude of change in species richness,spatial coverage,and sample coverage of plant records based on curation versus *** process of curation resulted in a decrease in species richness(synonym and error removal),but it significantly increased the number of records per *** contributed to a slight increase in species richness,via accumulation of new ***,curation led to increases in spatial coverage,species observed by locality,the number of plant records by species,and localities by species compared to ***,curationwas more efficient in producing new information compared to fieldwork,mainly because of the large number of records available in *** recommend intensive curatorial work as the first step in increasing biodiversity data quality and quantity,to identify bias and gaps at the regional scale that can then be targeted with *** stepwise strategy would enable fieldwork to be planned more costeffectively given the limited resources for biodiversity exploration and characterization.

关键词： Colombia Flora de Bogota Sample coverage Species richness Tropical Andes

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Is magnesium deficiency the major cause of needle chlorosis of Pinus taeda in Brazil?

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Journal of Forestry Research 2024年第2期35卷 209-221页

作者： Antônio carlos vargas Motta Shizuo Maeda Valdécio dos Santos dos Santos Rodrigues Tamires Maiara Ercole Stephen Arthur Prior Ana Elisa Lyra Brumat Amanda Pacheco Cardoso Moura Julierme Zimmer Barbosa João Bosco Vasconcellos Gomes Department of Soil Sciences and Agriculture Engineering Federal University of ParanáR.dos Funcionários1540.CuritibaParanáCEP 80035‑050Brazil Brazilian Agricultural Research Company Embrapa FlorestasEstr.da Ribeira–Br‑476Km 111–Parque Monte Castelo.ColomboParanáCEP 83411‑000Brazil United States Department of Agriculture‑Agricultural Research Service USDA-ARS National Soil Dynamics Laboratory411 South Donahue DriveAuburnAL 36832USA Reforestation Remasa Rodovia PR 170–Km 522.BiturunaParanáCEP 84640‑000Brazil Federal Institute of Southeast of Minas Gerais R.Luz Interior360.Juiz de ForaMinas Gerais CEP 36030‑713Brazil

Needle chlorosis(NC)in Pinus taeda *** in Brazil becomes more frequent after second and third harvest rotation *** a study to identify factors contributing to yellowing needle chorosis(YNC),trees were grown in soils originating from contrasting parent materials,and soils and needles(whole,green and chlorotic portions)from 1-and 2-year-old branches and the first and second needle flush release at four sites with YNC on *** were analyzed for various elements and *** soils had very low base levels(Ca^(2+),Mg^(2+)and K^(+))and P,suggesting a possible lack of multiple *** symptoms started at needle tips,then extended toward the needle base with *** flush needles had longer portions with YNC than second flush needles *** from the lower crown also had more symptoms along their length than those higher in the *** were similar to those reported for *** chlorotic portions,Mg and Ca concentrations were well below critical values;in particular,Mg levels were only one third of the critical value of 0.3 g kg^(-1).Collectively,results suggest that Mg deficiency is the primary reason for NC of *** in various parent soils in Brazil.

关键词： Nutritional deficiency Forest management Soil depletion Pine foliar analysis Needle chlorosis

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Earthquake distribution and lithospheric rheology beneath the Northwestern Andes, Colombia

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Geodesy and Geodynamics 2021年第1期12卷 1-10页

作者： Carla Lagardère carlos A.vargas Department of Geosciences Universidad Nacional de ColombiaBogotaColombia Ecole nationale superieure en environnement georessources et ingenierie du developpement durable(ENSEGID)BordeauxFrance

The rheological behavior of the lithosphere beneath the Northwestern(NW)Andes(Colombian)remains uncertain under a complex geological ***,we analyze the earthquake distribution and the stress drop on the western and the eastern of the transition area between the Upper Magdalena Valley(UMV)and the Middle Magdalena Valley(MMV),a zone related to a plate tectonic transition from steeper to flatter subduction style slabs(Nazca and Caribbean plates).Our results consistently explain the tectonic and geodynamic context of the study area supported in two rheological profiles,which reveal the brittle/ductile transition of the lithospheric crust and mantle and allow to constrain the lithospheric rheological *** subduction phenomenon of the Nazca Plate under the South American Plate is observed in the western *** the eastern region,we find a remarkable aseismic zone under the Eastern Cordillera below 20-km-deep,which made more difficultan accurate estimation of the crust/mantle *** seismic particularity leads us to support the hypothesis of a delamination process due to the tectonic overload generated by the Eastern Cordillera,and that promotes thermal *** results also suggest that the earthquake dataset correlated with rheological estimations may offer a consistent interpretation of the mechanical behavior of the lithosphere.

关键词： Lithosphere rheology Seismicity Northwestern Andes Delamination process

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Optimal Positioning Strategy for Multi-Camera Zooming Drones

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IEEE/CAA Journal of Automatica Sinica 2024年第8期11卷 1802-1818页

作者： Manuel vargas carlos Vivas Teodoro Alamo Department of System Engineering and Automation University of SevilleSeville 41092Spain

In the context of multiple-target tracking and surveillance applications,this paper investigates the challenge of determining the optimal positioning of a single autonomous aerial vehicle or agent equipped with multiple independently-steerable zooming cameras to effectively monitor a set of targets of *** camera is dedicated to tracking a specific target or cluster of *** key innovation of this study,in comparison to existing approaches,lies in incorporating the zooming factor for the onboard cameras into the optimization *** enhancement offers greater flexibility during mission execution by allowing the autonomous agent to adjust the focal lengths of the onboard cameras,in exchange for varying real-world distances to the corresponding targets,thereby providing additional degrees of freedom to the optimization *** proposed optimization framework aims to strike a balance among various factors,including distance to the targets,verticality of viewpoints,and the required focal length for each *** primary focus of this paper is to establish the theoretical groundwork for addressing the non-convex nature of the optimization problem arising from these *** this end,we develop an original convex approximation *** paper also includes simulations of diverse scenarios,featuring varying numbers of onboard tracking cameras and target motion profiles,to validate the effectiveness of the proposed approach.

关键词： Convex optimization projective transformation unmanned aerial vehicle visual object tracking visual surveillance.

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Establishing geothermometric constraints on the local geothermal gradients:Case study of the Eastern Cordillera Basin,Colombia

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Geodesy and Geodynamics 2018年第4期9卷 271-280页

作者： carlos A.Barrera carlos A.vargas Jorge E.Cortes Universidad Nacional de Colombia Carrera 45 No 26-85 Bogota Colombia Petromarkers Inc. 16850 Saturn Ln Houston TX 77058 United States

Geochemical analyses were performed on 170 coal bed-trapped groundwater samples from 97 underground mines located in the Eastern Cordillera Basin, Colombia. The waters analyzed in this paper are from exploited coal beds, located up to 0.73 km deep, which emerge along with the local fault *** hydrochemical facies were classified based on the concentration of major ions by inferring the equilibrium state and rock water source. The main hydrochemical facies presented in the groundwater study are SO_4-Ca-Mg, HCO_3-Ca, HCO_3-Ca-Mg, and SO_4-HCO_3 mixed waters. We used geothermometric equations to estimate the most probable temperature under in-situ conditions and the propagation of errors theory to test the results. The geothermal gradient in the study area is close to 30℃/km, which is consistent with measurements from oil wells within the study area. Principal Component Analysis was used to explain factors affecting formation water composition and hydrogeochemical evolution of aquifers.

关键词： Geothermometers Hydrochemistry Coal bed Formation waters Eastern Cordillera Basin

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Depth to the bottom of magnetic layer in South America and its relationship to Curie isotherm,Moho depth and seismicity behavior

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Geodesy and Geodynamics 2018年第1期9卷 93-107页

作者： Javier Idárraga-García carlos A.vargas Research Group on Geophysics Universidad Nacional de ColombiaBogotáColombia Deportment of Geosciences.Universidad Nacional de Colombia.Bogota.Colombia

We have estimated the DBML（depth to the bottom of the magnetic layer） in South America from the inversion of magnetic anomaly data extracted from the EMAG2 grid. The results show that the DBML values, interpreted as the Curie isotherm, vary between -10 and -60 km. The deepest values（〉-45） are mainly observed forming two anomalous zones in the central part of the Andes Cordillera. To the east of the Andes, in most of the stable cratonic area of South America, intermediate values（between -25 and-45 km） are predominant. The shallowest values（〈-25 km） are present in northwestern corner of South America, southern Patagonia, and in a few sectors to the east of the Andes Cordillera. Based on these results, we estimated the heat flow variations along the study area and found a very good correlation with the DBML. Also striking is the observation that the thermal anomalies of low heat flow are closely related to segments of flat subduction, where the presence of a cold and thick subducting oceanic slab beneath the continent, with a virtual absence of hot mantle wedge, leads to a decrease in the heat transfer from the deeper parts of the *** comparing our results with the Moho depths reported by other authors, we have found that the Curie isotherm is deeper than Moho in most of the South American Platform（northward to -20°S）, which is located in the stable cratonic area at the east of the Andes. This is evidence that the lithospheric mantle here is magnetic and contributes to the long wavelength magnetic signal. Also, our results support the hypothesis that the Curie isotherm may be acting as a boundary above which most of the crustal seismicity is concentrated. Below this boundary the occurrence of seismic events decreases dramatically.

关键词： Magnetic layer depth Curie isotherm Heat flow Crustal seismicity Flat subduction South America

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Is magnesium deficiency the major cause of needle chlorosis of Pinus taeda in Brazil?

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Journal of Forestry Research 2024年第2期 213-225页

作者： Ant?nio carlos vargas Motta Shizuo Maeda Valdécio dos Santos dos Santos Rodrigues Tamires Maiara Ercole Stephen Arthur Prior Ana Elisa Lyra Brumat Amanda Pacheco Cardoso Moura Julierme Zimmer Barbosa Jo?o Bosco Vasconcellos Gomes Department of Soil Sciences and Agriculture Engineering Federal University of Paraná Brazilian Agricultural Research Company Embrapa Florestas 3. United States Department of Agriculture-Agricultural Research Service USDA-ARS National Soil Dynamics Laboratory 4. Reforestation Remasa 5. Federal Institute of Southeast of Minas Gerais

Needle chlorosis(NC) in Pinus taeda L. systems in Brazil becomes more frequent after second and third harvest rotation cycles. In a study to identify factors contributing to yellowing needle chorosis(YNC), trees were grown in soils originating from contrasting parent materials, and soils and needles(whole, green and chlorotic portions) from 1-and 2-year-old branches and the first and second needle flush release at four sites with YNC on P. taeda were analyzed for various elements and properties. All soils had very low base levels(Ca2+, Mg2+and K+) and P, suggesting a possible lack of multiple elements. YNC symptoms started at needle tips, then extended toward the needle base with time. First flush needles had longer portions with YNC than second flush needles did. Needles from the lower crown also had more symptoms along their length than those higher in the canopy. Symptoms were similar to those reported for Mg. In chlorotic portions, Mg and Ca concentrations were well below critical values; in particular, Mg levels were only one third of the critical value of 0.3 g kg-1. Collectively, results suggest that Mg deficiency is the primary reason for NC of P. taeda in various parent soils in Brazil.

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Fast magnitude determination using a single seismological station record implementing machine learning techniques

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Geodesy and Geodynamics 2018年第1期9卷 34-41页

作者： Luis H.Ochoa Luis F.Nino carlos A.vargas Universidad Nacional de Colombia Carrera 45 N°26-85 Edificio Manuel Ancizar-Of:330BogotaColombia

In this work a Support Vector Machine Regression（SVMR） algorithm is used to calculate local magnitude（MI） using only five seconds of signal after the P wave onset of one three component seismic station. This algorithm was trained with 863 records of historical earthquakes, where the input regression parameters were an exponential function of the waveform envelope estimated by least squares and the maximum value of the observed waveform for each component in a single station. Ten-fold cross validation was applied for a normalized polynomial kernel obtaining the mean absolute error for different exponents and complexity parameters. The local magnitude（MI） could be estimated with 0.19 units of mean absolute error. The proposed algorithm is easy to implement in hardware and may be used directly after the field seismological sensor to generate fast decisions at seismological control centers, increasing the possibility of having an effective reaction.

关键词： Earthquake early warning Support Vector Machine Regression Earthquake Rapid response Local magnitude Seismic event Seismology Bogota Colombia

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Study of Spider Silk Fibers by Raman Microscopy

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American Journal of Analytical Chemistry 2018年第10期9卷 529-545页

作者： Maria Fernanda vargas-Charry carlos vargas-Hernández Laboratorio de Propiedades Opticas de Materiales (POM) Universidad Nacional de Colombia sede Manizales Manizales-Caldas Colombia

Spider silk fibers of species of the genera Araneus, Gasteracantha, and Linothele sericata were studied. The fibers are composed of axial threads and lateral villi, allowing adhesion to surfaces. Raman spectroscopy was used to determine the surface and internal composition of the threads forming the structure. In the three species, the characteristic amino acid peaks of the spider web were found between 2871 and 2975 cm-1, which belong to L-glycine, L-alanine, L-glutamine, and L-proline. The threads are composed of a protective layer mainly composed of amides, alanine, and glycine. The fibrils surrounding the axial fibers consist mainly of amide II (1533 cm-1), which allows adhesion between the thread and the surfaces onto which the spider weaves the web. For the genus Linothele sericata, there is a peak on the surface of this spider web located at 2145 cm-1, which is associated with isonitriles with R-N-C bonds.

关键词： Spider Silk Fibers Raman Spectroscopy

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Three-dimensional seismic attenuation tomography of Egypt

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Natural Science 2012年第8期4卷 608-623页

作者： Elsayed Fergany Mamdouh Abass carlos vargas Department of Geosciences Universidad Nacional de Colombia Bogota Colombia National Research Institute of Astronomy & Geophysics Helwan Cairo Egypt

The main purpose of the paper is assessing the three-dimensional (3-D) seismic tomography beneath Egyptto reveal the laws of the tectonic activity, dynamic features of the crust and the upper mantle as well as the thermal structure. Thecoda wave attenuation (Q-1c ) was obtained using the single scattering theory for the central frequencies of interest laid between 1 and 24 Hz. A regionalization of the estimated Q-1c values was performed by means of a generalized inversion *** obtained spatial distribution of 3-D attenuation results revealshigh contrasts between East and West Egypt. A remarkable contrast in the attenuation levels was compared with the tectonic structures, geothermal gradient and heat flow features. The highest attenuations are concentrated in the east and north western offshore regionsat central frequency 1.5 Hzthat draw a good matching with the seismic andthermal features of Egypt. Smaller attenuation levels were detected with young sediments of the Nile Valley from South to the northern triangle of Nile Delta basin except seismic active areas. Low or normal attenuation was detected at western desert where there is a stable and simple shelf. We can conclude that the extended highest attenuation joins to the strong seismic sources and geothermal structures at lower frequency and the centralized high attenuation takes place at moderate seismic sources at a higher frequency. The 3D attenuation maps can draw not only tectonic and geothermal structures but also the general geologic structure map.

关键词： Seismic Coda Waves Attenuation Tomography Seismicity Tectonic Geothermal Geologic Epoch

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