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In this work, we apply multi-temporal 1D-magnetotelluric (MT) surveys to estimate the space–time variations of the apparent resistivity ρ a and correlate these changes with seismic activity in the central part of Colombia (South America). We use the time series of the Earth's natural electric and magnetic fields registered at two MT stations of the National University of Colombia Seismological Network (RSUNAL), located in the Eastern Andean Cordillera, in the central part of Colombia, over several days. Assuming that large earthquakes may generate these types of anomalies, we identified positive results for the Mesetas earthquake (Mw6.0, Lon = 74.184° W, Lat = 3.462° N, H = 13 km-depth, 24 December 2019, UTC 19:03:55), with anomalies registered eight hours before the mainshock. The depth at which the resistivity anomaly was identified coincides with the depth of the earthquake hypocenter. The origin of these anomalies may be associated with the migration of fluids due to the change in the stress regime before, during, and after the earthquake. We hypothesize that before the occurrence of an earthquake, the stress field generates pore pressure gradients, promoting alterations in fluid migration that change the resistivity of the upper crust. [ABSTRACT FROM AUTHOR]

Background: Lung cancer is a public health problem, and squamous cell carcinoma (SCC) is the second most prevalent subtype of this neoplasm. Compared to other subtypes, including adenocarcinoma, SCC is less well understood in terms of molecular pathogenesis, limiting therapeutic options among targeted agents approved for other disease subgroups. In this study, we sought to characterize the SCC genomic profile using a validated Next Generation Sequencing (NGS) platform. Methods: The comprehensive NGS assay (TruSight Tumor 170) was used in order to target the full coding regions of 170 cancer-related genes on SCC samples. PD-L1 expression in tumor cells (TCs) was assessed using clone 22C3 (Dako). Clinical outcomes were correlated with molecular profile, including progression free survival (PFS), overall response rate (ORR), and overall survival (OS). Results: A total of 26 samples were included, median age was 67 years (r, 33–83) and 53.8% were men. Tobacco consumption was identified in all subjects (mean 34-year package). For first-line treatment 80.8% of patients received cisplatin or carboplatin plus gemcitabine. In terms of molecular profile, we identified a high prevalence of inactivating mutations in TP53 (61.5%), PIK3CA (34.6%), MLL2 (34.6%), KEAP1 (38.4%), and NOTCH1 (26.9%). PD-L1 expression ranged from negative, 1, 2–49, and ≥50% in 23.1, 38.5, 26.9, and 11.5%, respectively. Interestingly, the genetic alterations did not have an effect in PFS, OS or ORR in this study. However, PDL1 expression was higher among those who had mutations in TP53 (p = 0.037) and greater expression of PDL1 was related to PIK3CA alterations (p = 0.05). Conclusions: The genomic profile of SCC encompasses important genes including TP53, PIK3CA and KEAP1. TP53 mutations could be associated with PDL1 expression, generating hypothesis regarding specific treatment options. [ABSTRACT FROM AUTHOR]

Question: As a result of recent and substantial digitization efforts, herbaria are becoming important sources of data for vegetation scientists. Are such data sets appropriate to describe composition gradients and β‐diversity? When compared with phytosociological data, what are the differences in terms of composition (co‐occurrence) gradients depending on the considered scale? Location: Páramos (Neo‐tropical alpine ecosystems) of Colombia. Methods: We compared vegetation patterns from phytosociological relevés and reconstructed pseudo‐communities from herbarium collections in the Colombian high elevation páramo ecosystem using diversity partitioning and Mantel correlations. Results: Species composition differed in the two data sets, which could be explained by taxonomic bias towards charismatic species and overrepresentation of rare species in the herbarium data set, whereas common species were more frequently represented in the phytosociological data set. The two data sets showed a similarly preponderant importance of large‐scale differences when we looked at species accumulation across different scales. Small‐scale richness contributed more to total richness for the phytosociological data set, while richness at intermediate scales was more important in the herbarium data set. Finally, pairwise β‐diversity analyses did not show correlations between data sets, and common species showed similar ecological distribution patterns. Conclusions: We recommend caution to researchers who wish to describe β‐diversity patterns in local communities using only herbarium data. However, since the two data sets showed some complementarity in their composition patterns, we suggest that combining data from relevés (or plots) and occurrence data (herbarium records, citizen science, etc.) could be an efficient strategy for describing broader diversity patterns. We discuss the circumstances under which it could be advantageous to work with such combined data sets, in particular in relation to conservation issues. [ABSTRACT FROM AUTHOR]

The objective of this work was to determine the effect of advanced oxidation systems on the taxonomic and functional diversity of pathogenic microorganisms in the effluent of the wastewater treatment plant in Bogotá - Colombia ("El Salitre" WWTP) by metagenomics analysis. The taxonomic and functional diversity of the microorganisms, before and after oxidation treatment, was determined by Illumina mass sequencing, detecting human pathogenic genera as Pseudomonas (28.0%), Arcobacter (10.0%), Aeromonas (4.0%), Sulfurospirillum (4.0%), Salmonella (3.0%), and Clostridiales (3.0%). Likewise, pathogenicity factors such as antimicrobial resistance genes (ARGs) also were detected in high abundances (∼5% of metagenome reads). In the effluent treated with the photoelectro-Fenton system (for 5, 30, and 60 min), a significant reduction of pathogenicity factors was observed in all cases. ARGs, chemotaxis, quorum sensing, secretion systems, and toxins of pathogenic bacteria (such as Arcobacter , Pseudomonas , Serratia , and Salmonella) were reduced at near-zero log 2 values, demonstrating that the photoelectro-Fenton process is a promising alternative to reduce the biological risk associated with this pathogenicity factors. [Display omitted] [ABSTRACT FROM AUTHOR]

Using recordings of earthquakes on Oceanic Bottom Seismographs and onshore stations on the coastal margins of Colombia, Panama, and Ecuador, we estimate attenuation parameters in the upper lithosphere of the Panama Basin. The tomographic images of the derived coda-Q values are correlated with estimates of Curie Point Depth and measured and theoretical heat flow. Our study reveals three tectonic domains where magmatic/hydrothermal activity or lateral variations of the lithologic composition in the upper lithosphere can account for the modeled thermal structure and the anelasticity. We find that the Costa Rica Ridge and the Panama Fracture Zone are significant tectonic features probably related to thermal anomalies detected in the study area. We interpret a large and deep intrinsic attenuation anomaly as related to the heat source at the Costa Rica Ridge and show how interactions with regional fault systems cause contrasting attenuation anomalies. [ABSTRACT FROM AUTHOR]

carbon black (N330, N550 and N660) at 25 and 50 phr. In order to evaluate the performance of new natural rubber compounds obtained from Colombia, a benchmarking was done with other natural rubber compounds from Central America (Guatemala). For this purpose, tensile strength, module at 100 and 300%, vulcanization rheometer curves, hardness and dispersion analysis were done for both natural rubber compounds. It was found that the new natural rubber compound from Colombia has similar properties and behaviour compared to Guatemala natural rubber (TSR). The Colombia natural rubber obtained is a new standard mix with high potential applications in the rubber industry in Colombia and other countries of region of South America. [ABSTRACT FROM AUTHOR]

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In Colombia, less that 2% of Urban Solid Waste (USW) are treated in Solid Waste Recovery Facilities (SWRF), having in almost all cases operational losses close to 60%, leading to the closure of several plants. Based on that, this research was focused on the establishment of some minimal conditions for the sustainability of a financial-economic scenario of a SWRF in towns with less than 50,000 inhabitants, by combining System Dynamics and Structural Analysis tools. As result, it was identified that the i.) amount of potentially usable material received, ii.) incomes for material reception, and iii.) amount of recovered material for sale, become as Key of sustainability. For the simulated scenario it is concluded that with the current fee of solid waste reception, the increase of recovery efficiency and merchandising of materials, it would be necessary to receive at least 302 t/month, to reach a cost/benefit ratio equal to 0. However that value can change as a function of the regional characteristics and implemented technologies of each project, thus it is necessary the development of studies of a project in a determined location. [ABSTRACT FROM AUTHOR]

This paper deals with perpetrators harming our planet particularly in Colombia through activities that impact on the environmental stability. These actions are from a voracious quest for wealth under the alleged improvement of modus vivendi just offered to some communities, neglecting most cases damage caused is irreversible, all of this against many environmental regulations that supposedly seek protection of the only available habitat of homo sapiens. Firstly, approved concepts on a biological meaning try to answer these issues: What social and environmental costs, some institutions or individuals seek to obtain economic benefits and protection under a supposedly concept of development? And how state control agencies are performing the role that society has given them as a way to protect a sustainable environment? [ABSTRACT FROM AUTHOR]

Central Cordillera of Colombia near to the Nevado del Ruiz volcano is a seismically active area above the subducting slab of the Nazca plate and deforming upper crust of the Andes. Buildings in the region require strengthening against the effects of both types of hazards: earthquakes and volcanoes. During these trips, we will discuss the 13 November, 1985, Nevado del Ruiz Volcano eruption that destroyed the Armero city with about 22,000 deceases, as well the 25 January, 1999. Armenia earthquake (M 6.2) that killed about 2000 people and injured 4000 largely as the result of older, poorly constructed buildings. The economic impact of the quake on the region was significant with about 8000 coffee farms either completely or partially destroyed and over 13,000 structures either partially damaged or completely destroyed. Both phenomena are associated to a large-transversal structure termed Caldas tear, which is controlling strong motion earthquakes and the Quanternary volcanism of the northern Andes. [ABSTRACT FROM AUTHOR]

We applied the NMO and CRS (Common Reflector Surface) approaches to a complex geological area in order to compare their performances for obtaining enhanced images. Unlike NMO, CRS does not depend on a previous time velocity model and uses a hyperbolic equation to estimate 2D travel times through three parameters (Normal ray emergence angle, NIP and N wavefront curvatures). To obtain the image a solution provided by coherence analysis algorithm was used. A low quality Colombian seismic line acquired in Middle Magdalena basin was used, where a foothill geological area is characterized by a thrusting fault. The CRS provided an enhanced image which allowed a new geological interpretation that is best constrained with other regional observations. [ABSTRACT FROM AUTHOR]

The spatial variation of S-wave coda attenuation (Qc-1) in the Galeras volcano region is analyzed. The study region is at present an active magmatic system situated in the southwestern Colombian Andes. Qc-1 is estimated using seismograms from 435 volcano-tectonic earthquakes recorded at 31 stations of the Galeras seismograph network. Qc-1 is then imaged using a 3D spatial stacking procedure. The technique is based on the assumption of uniform distribution of Qc-1 over a spheroidal shell with its volume determined by the associated source-receiver distance. The resultant tomograms also show frequency dependence, which is interpreted in terms of the scale of the heterogeneities producing the scattering. High-attenuation anomalies are detected at high frequencies. Synthetic tests indicate the validity of the inversion technique. [ABSTRACT FROM AUTHOR]

Abstract: The Abanico del Quindío (AQ) fan, a volcaniclastic deposit from the Ruiz–Tolima volcanic complex (RTVC), Colombia, provides insight into recent deformation in the Central Andes. The use of geological observations, geophysical measurements, and estimates of fault-scarp ages constrain timing of recent tectonic activity. Gravity and magnetic analyses, along with geomorphologic cartography, allow the detection of lateral variations in basement distribution and at least three structural trends that cut the AQ: the Armenia fault (NNE), El Danubio fault (NNW), and Hojas Anchas fault (E–W). Recent deformation in the zone results from slip on the Armenia and El Danubio faults and suggests a maximum interval magnitude of 5.1< M w <6.3, with ages ranging between 2560±480yr B.P. and 4120±780yr B.P. Although no surface ruptures are associated with historical events on the fault segments in this zone, blind structures may have influenced the hypocentral distribution of events recorded after the Armenia Earthquake (M w 6.2, 25-01-1999). Further geophysical studies are needed to understand the Romeral Fault System and assess the earthquake hazard for the city of Armenia. [Copyright &y& Elsevier]

A geometric model for the subduction of the Nazca plate beneath the South American plate in southwestern of Colombia is proposed based on the relocation of hypocenters of local and distant earthquakes. By means of the simultaneous inversion of teleseismic P and SH body waves, the depths of the 15 events with Mw = 5.8 were constrained, and the hypocenters of the 250 earthquakes recorded between 1990 and 2005 by the International Seismological Centre (ISC) and U.S. Geological Survey, National Earthquake Information Center (NEIC) were constrained and relocated. A model is proposed for the hypocentral sections taking into account the trench along of the Earth and Colombia-Ecuador. Three different possible shapes of subduction of the Nazca plate in the Colombia-Ecuador trench were obtained: The first configuration, in the Cali A segment, the dip angle changes from17° to 45° down to a maximum depth of 100km; the second configuration, in the Popayán B and Nariño C segments, the dip angle holds approximately constant at 30° down to a maximum depth of 200 km; and the third configuration, in the Quito D segment, the dip angle changes of 9° to 50° to a maximum depth 220 km. The maximum depth of seismicity along the Colombia-Ecuador trench shows two increases, the first between latitudes 4.5°N-5°N and the second between the latitudes 1°S-2°S, which suggest that the presence of the Malpelo and Carnegie Ridges may generate a differential blockage at the Pacific Colombia-Ecuador basin. [ABSTRACT FROM AUTHOR]

One thousand seven hundred and eighty-six vertical-component, short-period observations of microearthquake codas from regional earthquakes recorded by 17 stations belonging to the National Seismological Network of Colombia were used to estimate seismic wave attenuation in Colombia. Local magnitudes range from 2.9 to 6.0 and only events occurring at hypocentral distances up to 255 km were considered for the analysis. The frequencies of interest lay between 1 and 19 Hz and the analysis was performed for each seismic station separately. Coda-wave attenuation ( Q−1c) was estimated by means of a single-scattering method whereas the separation of intrinsic absorption ( Q−1i) and scattering attenuation ( Q−1s) from total attenuation ( Q−1t) was performed using a multiple lapse time-window analysis based on the hypothesis of multiple isotropic scattering and uniform distribution of scatterers. A regionalization of the estimated Q0 ( Qc at 1 Hz) values was performed and a contour map of seismic coda attenuation in Colombia is presented, where four zones with significant variations of attenuation related to different geological and tectonic characteristics can be observed. The highest attenuation is linked to the central and western regions ( Q0 around 50 and 56) whereas a lower attenuation ( Q0 around 69 and 67) is assigned to the northern and eastern regions. Results show that the Q−1 values are frequency dependent in the considered frequency range, and are approximated by a least-square fit to the power law . The exponents of the frequency dependence law ranged from to 1.01 for to 1.78 for to 1.49 for Q−1s, and to 1.67 for Q−1t. On the other hand, intrinsic absorption is found to dominate over scattering in the attenuation process for most of the stations and frequency bands analysed. Some discrepancies have been observed between the theoretical model and the observations for some frequency bands which indicate that it would be necessary to consider models for depth-dependent velocity structure and/or non-isotropic scattering patterns. [ABSTRACT FROM AUTHOR]

The space-time variation of the parameter of attenuation Q-Coda in a sector of the Piedemonte Llanero was studied using the Coda waves. The estimation of the attenuation of the amplitude of coda is calculated by means of the Model of simple Isotropic Dispersion of Sato, from earthquakes seismograms happened in the region from September 1993 to June 2002. Following the methodology used by Aki and Chouet (1975), they analyzed seismograms in four centered bands to 1.5, 3, 6 and 12 Hertz with its corresponding bandwidths of 1, 2, 4 and 8 Hertz. And by regression to linear calculated the value of Qc to 1 Hertz. From the expression proposed by Puli to model the amplitude of the waves coda by means of ellipses, this expression was extended to calculate the space variation of the Qc-1, (anelastic tomography). And by inverse square minimums, the value of attenuation for each cell of the three-dimensional model was calculated. Their results were correlated with the regional tectonic frame showing that when the attenuation increases by depth, it corresponds to zones with Tectonics of thick skin and, on the contrary, where the attenuation diminishes by depth, it corresponds to zones with Tectonics of thin skin. On the other hand, the temporary variation of minimum values of Qc (maximum attenuations) was correlated to qualitatively earthquakes of magnitude greater to 3,5 and, in addition, the temporary distribution of Qc was quantified by dimension fractal showing that the grouping of the minimum values of Qc increases before ocurring a main event and its grouping decreases after occurring the main event. [ABSTRACT FROM AUTHOR]

Worldwide trends in the area under coca crops cultivation have been primarily motivated by illegal advances in Colombia around cocaine production. Thus, alternative ways for the final disposal of cocaine are needed and the evaluation of their possible economic and environmental advantages. This work aimed to compare incineration and biological degradation of cocaine by considering techno-economic and environmental aspects. There was a cocaine removal efficiency of 99.7% when bacterial C1T consortium was grown using cocaine as the sole carbon source. The biological degradation process exhibited a specific energy consumption and total potential environmental impact, 5 and 10 fold lower than the incineration process, respectively. The biological degradation process can also reach similar disposition unit prices as the incineration process (i.e., 1.00 USD/kg). [Display omitted] • Biological degradation is techno-economically feasible to dispose of cocaine. • Biological degradation has a lower potential environmental impact than incineration. • C1T consortium is an alternative to degrade cocaine and its derivate compounds. • Benzoylecgonine and benzoic acid are derived products from cocaine biodegradation. [ABSTRACT FROM AUTHOR]

As a comment on Seismic Electric Signals (SES) and earthquakes: A review of an updated VAN method and competing hypotheses for SES generation and earthquake triggering, herein we present the analysis of time series gathered by three MT stations located in the Eastern Cordillera of Colombia, for evaluating the electric and magnetic fields during an interval of several days. Records allow estimating multi-temporal apparent resistivity profiles in each station. Then, we correlate possible resistivity anomalies with seismicity, assuming that large earthquakes generated those anomalies. As an example, we identified a change in the apparent resistivity 7-h previous to the Mesetas earthquake (Mw6.0, December 24th, 2019). We would like to highlight that the resistivity anomaly was identified at the same depth as the earthquake hypocenter, and by more than one station. [ABSTRACT FROM AUTHOR]

In this study, the authors worked on identifying a possible relationship between electromagnetic signals (EM) and seismic events in the lithospheric system in the central region of Colombia. The data, both seismic records and electromagnetic signals, were taken from the catalog of the Seismological Network of the National University of Colombia (RSUNAL) and the catalog of the National Seismological Network of Colombia (RSNC). The project included the design and instrument testing phases for recording seismic signals, electrical potential variations, and magnetic field variations to try to identify possible relationships between these signals. Possible electromagnetic precursors for seismic events were observed, mainly magnetic disturbances, but it was not possible to locate evident electrical anomalies (Seismic Electric Signals - SES). Thus, although the results are not conclusive, the magnetic disturbances identified deserve further long-term analysis. [ABSTRACT FROM AUTHOR]

The Mutatá earthquake is a M w 6 earthquake which occurred in northwestern Colombia on September 14, 2016. This region is located at the junction between three tectonic plates, namely the South American, Nazca and Caribbean plates, and the Chocó-Panamá and Northern Andes Blocks. This event took place in the Murindo seismic zone, a zone characterized by a high seismic activity involving the Uramita fault zone, which defines the contact between the two blocks. In this study, we relocate the mainshock – aftershocks sequence and analyze the source characteristics of the Mutatá earthquake. Using data from the Colombian Seismological National Network, and after re-picking the 411 events, we obtain absolute locations exhibiting a NW-SE oriented cloud, with the mainshock being located 8 km away from its original location and at a depth of 17.6 km. The event cloud is situated at the intersection of three faults with different orientations, the NNW-SSE Uramita Fault, a NW-SE fault, and a NNE-SSW inferred fault. Using data coming from 8 broad-band seismographs within 300 km of the mainshock, we perform moment tensor and kinematic slip distribution inversions. The moment tensor inversion points to an event centroid at 20 km depth, with a predominantly double-couple mechanism. The fault orientations in the area, NW-SE orientation of the event cloud, and hypocenter – centroid technique, indicate that the NW-SE nodal plane likely corresponds to the fault plane giving a right-lateral strike-slip mechanism on a SW dipping plane. The rupture model estimated on this plane shows different slip patches, one being close to the mainshock centroid, and few other patches distributed around the mainshock except to the southeast where most of the aftershocks are located. The maximum slip for this model is approximately 0.16 m. The source characteristics of the 2016 Mutatá earthquake suggest then that secondary faults within the Murindo seismic zone can generate large earthquakes, potentially consisting in an important source of seismic hazard in this region. • Mainshock – aftershocks sequence forms a NW-SE elongated cluster. • Double-couple moment tensor showing a mostly right-lateral mechanism. • Slip distribution in all directions around the centroid location except to the southeast. • Highlight the necessity of regional studies to obtain reliable source characteristics. • Secondary faults in Murindo seismic cluster seem able to generate high magnitude events. [ABSTRACT FROM AUTHOR]

Abstract: Analysis of teleseismic records obtained in two broadband seismic stations of three components located on the Andean region of Colombia is presented in this work. The two stations are located at the Western Cordillera (WC), station BOL, and at the Central Cordillera (CC), station PBLA. The analysis of seismograms was performed by inversion of the receiver functions (RF) in order to obtain the crustal velocity structure beneath the receivers. The receiver function is a spectral ratio obtained from teleseismic earthquakes recorded by broadband seismic stations, which allows the calculation of the velocity structure beneath the receiver by removing source effects in the horizontal components of the seismic traces. Data stacking was performed in order to improve signal to noise ratio and then the data was inverted by using two optimization algorithms: a genetic algorithm (GA), and a simulated annealing algorithm (SA). The present work calculates the receiver functions using teleseismic earthquakes at epicentral distances (Δ) ranging between 30° and 90° and recorded at the two stations within the years 2007 and 2009. Delay times between P and PS waves converted at the Moho boundary were used to constrain the velocity structure. The receiver functions at the stations were generated from seismic events within a broad range of back azimuth. Data from gravity and magnetism were also used during the geophysical survey. The depth of the Moho boundary was found to be at 40 km in the WC beneath station BOL and at 43 km in the CC beneath station PBLA. The upper crust, with a thickness of 5 km, is characterized by a shear wave velocity of about 3.0 km s−1; the shallower layers, at approximately 1.0 km, have shear wave velocities between 2.2 and 2.6 km s−1, which corresponds to sediments overlying the upper crust. These observations support the hypothesis of a thickness of the crust at the root of the mountain range to be between 32 and 50 km. The calculated receiver functions were compared with artificial ones generated from the inversion of 48000 models of horizontal layers for each station using a GA and an SA that allowed a satisfactory coverage of all the sample space in order to avoid non-unique solutions. Beneath station BOL a moderate low-velocity zone (LVZ) was found, which was caused by accretionary processes of the ophiolite complex in the WC. [Copyright &y& Elsevier]

Abstract: Vertical-component, short period seismograms from 435 well located volcano-tectonic earthquakes are used to estimate S-wave attenuation in the Galeras volcanic complex (south western Colombia) using coda waves. The coda magnitudes (M c ) of the events are less than 2. Event depths are less than 10km and hypocentral distances up to 16km. Intrinsic absorption () and scattering attenuation () are estimated by means of a fitting procedure between the observed and synthetic coda envelopes in four frequency bands (1–2, 2–4, 4–8, and 8–12Hz). The observations are compared with the theoretical predictions by an accurate approximate analytical solution of the radiative transfer equation which is based on the assumptions of multiple isotropic scattering, impulsive isotropic point source, and a medium with homogeneous scattering and absorption properties. Results show that scattering is strong and it constitutes the predominant attenuation effect in this region. In the frequency range analyzed in this study the values of the mean free path for scattering of S waves range between 2.7≤ l ≤8.1km, which are clearly higher than those obtained in other volcanic regions of the world, but about two orders of magnitude smaller than average estimates for the Earth''s crust. The characteristic length scale of intrinsic absorption gives values of 2.5≤ l a ≤77km, which are on the same order as the usual values for the Earth''s crust. [Copyright &y& Elsevier]