6.1 Proyectos de investigación científica
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Publicación10-pi-Electron arenes a la carte: structure and bonding of the [E-(CnHn)-E](n-6) (E = Ca, Sr, Ba; n=6-8) complexes( 2016)
;Mondal, S ;Cabellos, JL ;Pan, S ;Osorio, E ;Torres-Vega, JJ ;Tiznado, W ;Restrepo, AMerino, GEn este artículo, brindamos evidencia sólida para demostrar que, entre una diversidad estructural abrumadora, los metales alcalinotérreos (Ca, Sr, Ba) tienen la capacidad de formar compuestos sándwich invertidos con C6H6, C7H7+ y C8H82+ de simetría Dnh y fórmula general [E –(CnHn)–E]n−6 (n = 6–8) con núcleos aromáticos planares de 10 π electrones en virtud de la transferencia de dos electrones por átomo de metal al anillo. -
Publicación112 hormonal supplementation strategies for improvement of pregnancy rates in embryo transfer in alpacas(CSIRO Publishing, 2017)
;Vivanco-Mackie, H. W. ;Ponce-Salazar, M. D. ;Miguel-Gonzales, M. ;Youngs, C. R. ;Osorio, C.Asparrin, M.The aim was to improve the pregnancy rate in recipient alpacas following embryo transfer. Two experiments were carried out, Experiment 1 in the southern highlands (4,100 m elevation) and Experiment 2 (E2) in the central highlands (3,200 m elevation) of the Peruvian Andes. In both experiments, a group of alpaca donors was subjected to superovulation and embryo flushing as per procedures already described (Vivanco 2013 29th Annu. Mtg. European Embryo Transfer Association, 43–74). The synchronization of the recipient alpacas and ovulation induction in both experiments was made by ultrasonography selection of the alpacas with follicles greater than 8 mm and their exposure to vasectomized males followed by an injection of GnRH (0.0042 mg of acetate of buserelin, Buserelina Zoovet®, Laboratorio Zoovet, Santa Fe, Argentina). The embryo transfers in both locations were made by laparoscopically aided laparotomy 6.5 days after ovulation induction. In Experiment 1, 29 recipient alpacas were distributed in 2 treatments: treatment 1 (n = 14) was the control (no hormonal supplementation); alpacas in treatment 2 (n = 15) received an injection of 300 IU of eCG (Novormon®, Partnar Animal Health, Port Huron, MI, USA) and the insertion of an intravaginal sponge containing 60 mg of medroxyprogesterone acetate (Progespon®, Syntex SA, Buenos Aires, Argentina) 72 h after the injection of the GnRH applied at ovulation induction, the sponges remained in the vagina of the recipients up until Day 21 post-transfer. In Experiment 2, ten recipient alpacas were distributed into 2 treatments, treatment 1 as the control (n = 5, no hormonal supplementation) and treatment 2 (n = 5) in which the recipient alpacas received a dose of a nonsteroidal anti-inflammatory (2 mg/kg of tolfenamic acid, Tolfén L.A. 8%®, Agrovet Market Animal Health, Lima, Peru) 12 h before the embryo transfer with the aim of blocking PGF2α secretion and preventing corpus luteum (CL) regression. At time of transfer, control recipients in Experiment 1 showed in average 0.71 ± 0.71 follicles and 1.14 ± 0.53 CL and the treatment 2 recipients showed 2.73 ± 2.52 follicles and 1.20 ± 0.56 CL, respectively, and there was no significant differences (P > 0.05) between treatment groups in the pregnancy rates 60 days post-transfer, being 35.7% (5/14) and 26.7% (4/15) for treatment 1 (control) and 2 (hormonally supplemented), respectively. In Experiment 2, the number of follicles and CL were not recorded; the differences between treatments for pregnancy rates were also nonsignificant (P > 0.05), the pregnancy rates were 20% (1/5) and 40% (2/5) for treatment 1 (control) and treatment 2 (injected with anti-inflammatory) respectively. In the first experiment, the hormonal treatment increased the number of non-ovulatory follicles; this could have negatively influenced its effectivity on increasing pregnancy rates. In the second experiment, a tendency can be observed for better holding rates in alpacas receiving the anti-inflammatory treatment; it will be necessary to increase the number of observations in a new experiment in order to determine if this will have a significant effect on improving holding rates in alpacas. -
Publicación1D TiO2 Nanostructures Prepared from Seeds Presenting Tailored TiO2 Crystalline Phases and Their Photocatalytic Activity for Escherichia coli in Water( 2018)
;Cabrera, J ;Acosta, D ;Lopez, A ;Candal, RJ ;Marchi, C ;Garcia, P ;Rios, DRodriguez, JMTiO2 nanotubes were synthesized by alkaline hydrothermal treatment of TiO2 nanoparticles with a controlled proportion of anatase and rutile. Tailoring of TiO2 phases was achieved by adjusting the pH and type of acid used in the hydrolysis of titanium isopropoxide (first step in the sol-gel synthesis). The anatase proportion in the precursor nanoparticles was in the 3–100% range. Tube-like nanostructures were obtained with an anatase percentage of 18 or higher while flake-like shapes were obtained when rutile was dominant in the seed. After annealing at 400°C for 2 h, a fraction of nanotubes was conserved in all the samples but, depending on the anatase/rutile ratio in the starting material, spherical and rod-shaped structures were also observed. -
Publicación3D elasticity numerical solution for the static behavior of FGM shells(Elsevier Ltd, 2020)
;Monge J.C.Mantari J.L.Se presenta una solución numérica para el análisis estático tridimensional de láminas graduadas funcionalmente con curvatura constante. La solución se basa en tres ecuaciones de elasticidad escritas en coordenadas curvilíneas ortogonales que son válidas para paneles de cubierta esféricos, cilíndricos y placas rectangulares. Las ecuaciones en términos de las variables de la superficie media se resuelven mediante una suma de armónicos en términos del método de Navier, que es válido solo para estructuras simplemente apoyadas. Las ecuaciones en función de la dirección del espesor se resuelven numéricamente por el método de Cuadratura Diferencial (DQM) que permitió calcular fácilmente la derivada aproximada de una función utilizando una suma ponderada de las funciones evaluadas en una determinada grilla. Las capas de la estructura se discretizan por separado mediante la cuadrícula de Chebyshev-Gauss-Lobatto y los polinomios de interpolación de Lagrange se consideran como funciones base. La continuidad interlaminar del corte transversal se impone como parte de las condiciones de contorno del método presentado. Las condiciones de contorno de las tensiones fuera del plano en la parte superior e inferior debidas a las cargas aplicadas en la lámina también se consideran para el análisis, como resultado, este método puede predecir el comportamiento correcto de la distribución a través del espesor de las fuerzas transversales. hace hincapié Este método permitió discretizar fácilmente el material en términos de la dirección del espesor y se analizaron varios tipos de estructuras de sándwich y capas individuales graduadas funcionalmente con núcleo graduado funcionalmente. Se analizan varias láminas sometidas a carga distribuida bisinusoidal y uniforme. Los resultados se comparan con otras soluciones tridimensionales propuestas en la literatura y modelos bidimensionales precisos. © 2019 -
PublicaciónA categorization of simultaneous localization and mapping knowledge for mobile robots(Association for Computing Machinery, 2020)
;Cornejo Lupa M.A. ;Ticona-Herrera R.P. ;Cardinale Y.Barrios-Aranibar D.Los robots autónomos están desempeñando un papel importante en las actividades académicas, tecnológicas y científicas. Por lo tanto, su comportamiento es cada vez más complejo. Las principales tareas de los robots autónomos incluyen mapear un entorno y localizarse a sí mismos. Estas tareas comprenden el problema de localización y mapeo simultáneos (SLAM). La representación del conocimiento de SLAM (p. ej., características del robot, información del entorno, información de mapeo y ubicación), con un modelo estándar y bien definido, proporciona la base para desarrollar soluciones eficientes e interoperables. Sin embargo, hasta donde sabemos, no existe una clasificación común de tales conocimientos. Muchos trabajos existentes basados en la Web Semántica han formulado ontologías para modelar información relacionada solo con algunos aspectos de SLAM, sin un arreglo estándar. En este artículo proponemos una categorización del conocimiento gestionado en SLAM, basada en ontologías existentes y principios de SLAM. También clasificamos ontologías recientes y populares según nuestras categorías propuestas y destacamos las lecciones a aprender de las soluciones existentes. © 2020 ACM. -
PublicaciónA comparative study of linen (Flax) fibers as reinforcement of fly ash and clay brick powder based geopolymers(IOP Publishing, 2018-10-26)
;Silva, G. ;Kim de Aguilar, Suyeon ;Castañeda, A. ;Donayre, R. ;Nakamatsu Kuniyoshi, Javier ;Aguilar, R. ;Korniejenko, K. ;?ach, M.Miku?a, J.Los geopolímeros tienen un gran potencial para el desarrollo de materiales de construcción sostenibles debido a la utilización de subproductos industriales y materiales de desecho para su producción. La introducción de fibras naturales en matrices de geopolímeros ha mostrado resultados interesantes para producir materiales de construcción alternativos con propiedades mecánicas mejoradas. Esta investigación explora el uso de fibras de lino (lino) como refuerzo de geopolímeros a base de polvo de ladrillo de arcilla y geopolímeros a base de cenizas volantes. Las fibras de lino se obtuvieron del Instituto de Fibras Naturales y Plantas Medicinales, mientras que el polvo de ladrillo de arcilla se obtuvo de los residuos de construcción en Lima (Perú) y las cenizas volantes se extrajeron de Skawina (Polonia). La influencia de la adición de fibras de lino en las propiedades mecánicas de la matriz de geopolímero se estudió mediante pruebas de compresión no confinada y pruebas de flexión de tres puntos. Los resultados muestran que la adición de fibras de lino mejoró significativamente tanto la resistencia a la compresión como a la flexión de los geopolímeros a base de cenizas volantes y polvo de ladrillos de arcilla. -
PublicaciónA Complementary Mechanism of Bacterial mRNA Translation Inhibition by Tetracyclines(Frontiers Media S.A., 2021)
;Barrenechea V. ;Vargas-Reyes M. ;Quiliano M.Milón P.Tetracycline has positively impacted human health as well as the farming and animal industries. Its extensive usage and versatility led to the spread of resistance mechanisms followed by the development of new variants of the antibiotic. Tetracyclines inhibit bacterial growth by impeding the binding of elongator tRNAs to the ribosome. However, a small number of reports indicated that Tetracyclines could also inhibit translation initiation, yet the molecular mechanism remained unknown. Here, we use biochemical and computational methods to study how Oxytetracycline (Otc), Demeclocycline (Dem), and Tigecycline (Tig) affect the translation initiation phase of protein synthesis. Our results show that all three Tetracyclines induce Initiation Factor IF3 to adopt a compact conformation on the 30S ribosomal subunit, similar to that induced by Initiation Factor IF1. This compaction was faster for Tig than Dem or Otc. Furthermore, all three tested tetracyclines affected IF1-bound 30S complexes. The dissociation rate constant of IF1 in early 30S complexes was 14-fold slower for Tig than Dem or Otc. Late 30S initiation complexes (30S pre-IC or IC) exhibited greater IF1 stabilization by Tig than for Dem and Otc. Tig and Otc delayed 50S joining to 30S initiation complexes (30S ICs). Remarkably, the presence of Tig considerably slowed the progression to translation elongation and retained IF1 in the resulting 70S initiation complex (70S IC). Molecular modeling of Tetracyclines bound to the 30S pre-IC and 30S IC indicated that the antibiotics binding site topography fluctuates along the initiation pathway. Mainly, 30S complexes show potential contacts between Dem or Tig with IF1, providing a structural rationale for the enhanced affinity of the antibiotics in the presence of the factor. Altogether, our data indicate that Tetracyclines inhibit translation initiation by allosterically perturbing the IF3 layout on the 30S, retaining IF1 during 70S IC formation, and slowing the transition toward translation elongation. Thus, this study describes a new complementary mechanism by which Tetracyclines may inhibit bacterial protein synthesis. © Copyright © 2021 Barrenechea, Vargas-Reyes, Quiliano and Milón. -
PublicaciónA differential DNA methylome signature of pulmonary immune cells from individuals converting to latent tuberculosis infection(Nature Research, 2021)
;Karlsson L. ;Das J. ;Nilsson M. ;Tyrén A. ;Pehrson I. ;Idh N. ;Sayyab S. ;Paues J. ;Ugarte-Gil C. ;Méndez-Aranda M.Lerm M.Tuberculosis (TB), caused by Mycobacterium tuberculosis, spreads via aerosols and the first encounter with the immune system is with the pulmonary-resident immune cells. The role of epigenetic regulations in the immune cells is emerging and we have previously shown that macrophages capacity to kill M. tuberculosis is reflected in the DNA methylome. The aim of this study was to investigate epigenetic modifications in alveolar macrophages and T cells in a cohort of medical students with an increased risk of TB exposure, longitudinally. DNA methylome analysis revealed that a unique DNA methylation profile was present in healthy subjects who later developed latent TB during the study. The profile was reflected in a different overall DNA methylation distribution as well as a distinct set of differentially methylated genes (DMGs). The DMGs were over-represented in pathways related to metabolic reprogramming of macrophages and T cell migration and IFN-? production, pathways previously reported important in TB control. In conclusion, we identified a unique DNA methylation signature in individuals, with no peripheral immune response to M. tuberculosis antigen who later developed latent TB. Together the study suggests that the DNA methylation status of pulmonary immune cells can reveal who will develop latent TB infection. © 2021, The Author(s). -
PublicaciónA distance between bounded linear operators(Elsevier BV, 2020)
;Jung, W. ;Metzger, R. ;Morales, C. A.Villavicencio, H.We extend the classical Banach-Mazur distance [3] from Banach spaces to linear operators between these spaces. We prove in the finite dimensional case that the corresponding topology is metrizable, complete, separable and locally compact. Furthermore, we prove that the Banach-Mazur compactum embeds isometrically into the resulting topological space. (C) 2020 Elsevier B.V. All rights reserved. -
PublicaciónA FAIR evaluation of public datasets for stress detection systems(IEEE Computer Society, 2020)
;Cuno A. ;Condori-Fernandez N. ;Mendoza A.Lovon W.R.Nowadays, datasets are an essential asset used to train, validate, and test stress detection systems based on machine learning. In this paper, we used two sets of FAIR metrics for evaluating five public datasets for stress detection. Results indicate that all these datasets comply to some extent with the (F)indable, (A)ccessible, and (R)eusable principles, but none with the (I)nteroperable principle these findings contribute to raising awareness on (i) the need for the FAIRness development and improvement of stress datasets, and (ii) the importance of promoting open science in the affective computing community. © 2020 IEEE. -
PublicaciónA generative adversarial network approach for super-resolution of sentinel-2 satellite images(International Society for Photogrammetry and Remote Sensing, 2020)
;Pineda F. ;Ayma V.Beltran C.Las imágenes de satélite de alta resolución siempre han tenido una gran demanda debido al mayor detalle y precisión que ofrecen, así como al amplio alcance de los campos en los que se podrían aplicar; sin embargo, los satélites en operación que ofrecen imágenes de muy alta resolución (VHR) han experimentado un aumento importante, pero se mantienen en una proporción menor frente a los satélites de menor resolución (HR) existentes. Los modelos recientes de redes neuronales convolucionales (CNN) son muy adecuados para aplicaciones con procesamiento de imágenes, como la mejora de la resolución de imágenes; pero para obtener un resultado aceptable, es importante, no solo definir el tipo de arquitectura de la CNN, sino también el conjunto de imágenes de referencia para entrenar el modelo. Nuestro trabajo propone una alternativa para mejorar la resolución espacial de las imágenes HR obtenidas por el satélite Sentinel-2 utilizando las imágenes VHR de PeruSat1, un satélite peruano, que sirven como referencia para la implementación del enfoque de superresolución basado en una Red Generativa Adversarial ( modelo GAN), como alternativa para la obtención de imágenes VHR. El conjunto de datos de imágenes VHR PeruSat-1 se utiliza para el proceso de entrenamiento de la red. Los resultados obtenidos se analizaron teniendo en cuenta las relaciones pico de señal a ruido (PSNR) y la similitud estructural (SSIM). Finalmente, se presentan algunos resultados visuales, sobre un conjunto de datos de prueba dado, para que también se pueda analizar el rendimiento del modelo. © 2020 Archivos Internacionales de Fotogrametría, Teledetección y Ciencias de la Información Espacial - Archivos ISPRS. -
PublicaciónA genomotaxonomy view of the bradyrhizobium genus(Frontiers Media S.A., 2019)
;Ormeño-Orrillo E.Martínez-Romero E.Whole genome analysis of the Bradyrhizobium genus using average nucleotide identity (ANI) and phylogenomics showed the genus to be essentially monophyletic with seven robust groups within this taxon that includes nitrogen-fixing nodule forming bacteria as well as free living strains. Despite the wide genetic diversity of these bacteria no indication was found to suggest that the Bradyrhizobium genus have to split in different taxa. Bradyrhizobia have larger genomes than other genera of the Bradyrhizobiaceae family, probably reflecting their metabolic diversity and different lifestyles. Few plasmids in the sequenced strains were revealed from rep gene analysis and a relatively low proportion of the genome is devoted to mobile genetic elements. Sequence diversity of recA and glnII gene metadata was used to theoretically estimate the number of existing species and to predict how many would exist. There may be many more species than those presently described with predictions of around 800 species in nature. Different arguments are presented suggesting that nodulation might have arose in the ancestral genus Bradyrhizobium. Copyright © 2019 Ormeño-Orrillo and Martínez-Romero. -
PublicaciónA geostatistical method in GIS to estimate the amount of seabird guano accumulated on islands and headlands of Perú(Asociacion Argentina de Ecologia, 2020)
;Sifuentes-García Á. ;Zavalaga C.B.Lozano-Sanllehi S.The ‘guano of the islands’ in Perú is the excrement of cormorants, boobies and pelicans (guano birds), accumulated in large deposits on islands and headlands. This guano is harvested and marketed by the governmental agency AGRORURAL to meet the demands of local organic agriculture. As part of its management and commercialization plans, AGRORURAL estimates the total quantity of guano built-up on the seabird colonies using a volumetric method. The objective of this research was to propose an alternative geostatistical method that uses the volumetric data collection as baseline but incorporates the slope of the terrain and makes estimations of the total amount and distribution of guano using an interpolation grid model in a Geographic Information System (GIS). The data of the slope of the terrain, depth of guano layer, guano density and proportion guano/rock of georeferenced sampling points (taken with a hand-held GPS) on the island/headland surface were used to interpolate the quantity of guano over the entire surface using a raster kriging model, so that each cell contained an estimated quantity of guano. For this study, six guano bird colonies were visited between June 2014 and February 2018. Based on the geostatistical method, the total quantity of guano estimated varied between 10921 t on Isla Mazorca and 26142 t on Isla Guañape Sur. The GIS grid maps showed that the quantity of guano deposits was not uniformly distributed over the island/headland surface. When the guano total quantity estimates based on the geostatistical method were validated with the amount of guano harvested, the estimation error was less than 18%. This error may decrease with the use of a submetric GPS, ground-penetrating radars and augers. An accurate method of guano volume quantification is crucial for budget, logistic and marketing planning of the guano islands and headlands of Perú. © 2020, Asociacion Argentina de Ecologia. All rights reserved. -
PublicaciónA Methodological Approach to Compare Ontologies: Proposal and Application for SLAM Ontologies(Association for Computing Machinery, 2020)
;Cardinale Y. ;Cornejo-Lupa M.A. ;Ticona-Herrera R.Barrios-Aranibar D.Representation of the knowledge related to any domain with flexible and well-defined models, such as ontologies, provides the base to develop efficient and interoperable solutions. Hence, a proliferation of ontologies in many domains is unleashed. It is necessary to define how to compare such ontologies to decide which one is the most suitable for specific needs of users/developers. Since the emerging developing of ontologies, several studies have proposed criteria to evaluate them. Nevertheless, there is still a lack of practical and reproducible guidelines to drive a comparative evaluation of ontologies as a systematic process. In this paper, we propose a methodological process to qualitatively and quantitatively compare ontologies at Lexical, Structural, and Domain Knowledge levels, considering Correctness and Quality perspectives. Since the evaluation methods of our proposal are based in a golden-standard, it can be customized to compare ontologies in any domain. To show the suitability of our proposal, we apply our methodological approach to conduct a comparative study of ontologies in the robotic domain, in particularly for the Simultaneous Localization and Mapping (SLAM) problem. With this study case, we demonstrate that with this methodological comparative process, we are able to identify the strengths and weaknesses of ontologies, as well as the gaps still needed to fill in the target domain (SLAM for our study case). © 2020 ACM. -
PublicaciónA mixture of extracts from Peruvian plants (black maca and yacon) improves sperm count and reduced glycemia in mice with streptozotocin-induced diabetes(Taylor & Francis, 2013)
;Gonzales G.F. ;Gonzales-Castañeda C.Gasco M.We investigated the effect of two extracts from Peruvian plants given alone or in a mixture on sperm count and glycemia in streptozotocin-diabetic mice. Normal or diabetic mice were divided in groups receiving vehicle, black maca (Lepidium meyenii), yacon (Smallanthus sonchifolius) or three mixtures of extracts black maca/yacon (90/10, 50/50 and 10/90%). Normal or diabetic mice were treated for 7 d with each extract, mixture or vehicle. Glycemia, daily sperm production (DSP), epididymal and vas deferens sperm counts in mice and polyphenol content, and antioxidant activity in each extract were assessed. Black maca (BM), yacon and the mixture of extracts reduced glucose levels in diabetic mice. Non-diabetic mice treated with BM and yacon showed higher DSP than those treated with vehicle (p < 0.05). Diabetic mice treated with BM, yacon and the mixture maca/yacon increased DSP, and sperm count in vas deferens and epididymis with respect to non-diabetic and diabetic mice treated with vehicle (p < 0.05). Yacon has 3.05 times higher polyphenol content than in maca, and this was associated with higher antioxidant activity. The combination of two extracts improved glycemic levels and male reproductive function in diabetic mice. Streptozotocin increased 1.43 times the liver weight that was reversed with the assessed plants extracts. In summary, streptozotocin-induced diabetes resulted in reduction in sperm counts and liver damage. These effects could be reduced with BM, yacon and the BM+yacon mixture. -
PublicaciónA Multiplex and Colorimetric Reverse Transcription Loop-Mediated Isothermal Amplification Assay for Sensitive and Rapid Detection of Novel SARS-CoV-2(Frontiers Media S.A., 2021)
;Juscamayta-López, E. ;Valdivia, F. ;Horna, H. ;Tarazona, D. ;Linares, L. ;Rojas, N.Huaringa, M.Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a major threat to public health. Rapid molecular testing for convenient and timely diagnosis of SARS-CoV-2 infections represents a challenge that could help to control the current pandemic and prevent future outbreaks. We aimed to develop and validate a multiplex and colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay using lyophilized LAMP reagents for sensitive and rapid detection of SARS-CoV-2. LAMP primers were designed for a set of gene targets identified by a genome-wide comparison of viruses. Primer sets that showed optimal features were combined into a multiplex RT-LAMP assay. Analytical validation included assessment of the limit of detection (LoD), intra- and inter-assay precision, and cross-reaction with other respiratory pathogens. Clinical performance compared to that of real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) was assessed using 278 clinical RNA samples isolated from swabs collected from individuals tested for COVID-19. The RT-LAMP assay targeting the RNA-dependent RNA polymerase (RdRp), membrane (M), and ORF1ab genes achieved a comparable LoD (0.65 PFU/mL, CT=34.12) to RT-qPCR and was 10-fold more sensitive than RT-qPCR at detecting viral RNA in clinical samples. Cross-reactivity to other respiratory pathogens was not observed. The multiplex RT-LAMP assay demonstrated a strong robustness and acceptable intra- and inter-assay precision (mean coefficient of variation, 4.75% and 8.30%). Diagnostic sensitivity and specificity values were 100.0% (95% CI: 97.4–100.0%) and 98.6% (95% CI: 94.9–99.8%), respectively, showing high consistency (Cohen’s kappa, 0.986; 95% CI: 0.966–1.000; p<0.0001) compared to RT-qPCR. The novel one-step multiplex RT-LAMP assay is storable at room temperature and showed similar diagnostic accuracy to conventional RT-qPCR, while being faster (<45 min), simpler, and cheaper. The new assay could allow reliable and early diagnosis of SARS-CoV-2 infections in primary health care. It may aid large-scale testing in resource-limited settings, especially if it is integrated into a point-of-care diagnostic device. © Copyright © 2021 Juscamayta-López, Valdivia, Horna, Tarazona, Linares, Rojas and Huaringa. -
PublicaciónA Network for Advancing Dendrochronology, Dendrochemistry and Dendrohydrology in South America(Tree Ring Society, 2020)
;Aguilera-Betti I. ;Lucas C. ;Ferrero M.E.Muñoz A.A.Tree-ring research (TRR) in South America (SA) continues to make important contributions in multiple sub-disciplines, including dendrochemistry and dendrohydrology. This report describes some of the advances in TRR in SA presented in a two-day International Meeting Research entitled "An International Network to Promote Advances in Dendrochronology in South America", organized by the Laboratory of Dendrochronology and Environmental Studies of the Pontifical Catholic University of Valparaíso in Valparaíso, Chile, on January 21-22, 2019. The objective of the meeting was to communicate recent advances in TRR within a network of laboratories in Argentina, Brazil, Chile, Peru, and Uruguay. Novel methodologies and results in dendrochemistry and wood anatomy were also presented by collaborating researchers from German institutions. This report describes some of the research within the subdisciplines of tree-ring science, including dendrochemistry, anatomy and dendrohydrology, and their application to understanding spatio-temporal variability in heavy metal contamination, climate, hydrology, fire regimes and other critical components of South American forest and woodland ecosystems. The meeting demonstrated expansion and diversification of inquiry and applications of TRR in SA, whereby collaboration across research centers has been critical for the advances made in broad-scale comparative studies as well as multi-proxy approaches and the study of global and hemisphere-scale climate phenomena. Copyright © 2020 by the Tree-Ring Society. -
PublicaciónA novel inexpensive electrochemical sensor for pyrazinoic acid as a potential tool for the identification of pyrazinamide-resistant Mycobacterium tuberculosis(Wolters Kluwer Medknow Publications, 2018)
;Rueda D. ;Furukawa R. ;Fuentes P. ;Comina G. ;Rey De Castro N.G. ;Requena D. ;Gilman R.H. ;Sheen P.Zimic M.Tuberculosis (TB) is a significant cause of morbidity and mortality worldwide. The patient compliance with the long treatment regimens is essential for successful eradication. Pyrazinamide (PZA) shortens these regimens from 9 to 6 months, and therefore, improves treatment completion rates. Although PZA is a first-line medication for the treatment of TB, no simple or reliable assay to determine PZA resistance is yet available. In the presence of PZA, only susceptible Mycobacterium tuberculosis strains release pyrazinoic acid (POA). Therefore, the measurement and quantification of released POA is an indicator of PZA resistance. -
PublicaciónA novel portable device for crawling waves sonoelastography: Experimental study(SPIE, 2020)
;Ancajima P.A. ;Romero S.E. ;Gonzalez E.A.Castañeda B.Crawling Waves Sonoelastography (CWS) is an elastography technique based on an interference pattern produced by the application of two external vibration sources. In this study, a 3D printed holder was designed to overcome the compatibility limitations of normal excitation modules for different ultrasound systems, previously developed in the literature. This holder was assembled with a transducer and two voice coil actuators, and its performance was tested in homogeneous and inclusion tissue-mimicking phantom. A phase derivative estimator was used to reconstruct the shear wave speed (SWS) map. The coefficient of variation (CV), bias and contrast-to-noise ratio (CNR) were used as quantitative metrics for comparison. These metrics have shown a comparable SWS estimation in the background (SWSb) of the homogeneous phantom with previous studies (e.g. SWSb = 3.58± 0.42 m/s). In the same way, the SWS of the inclusion (SWSi) was distinguished from the background with an accurate SWS value (e.g. SWSi = 5.64 ±0.42 m/s and SWSb = 3.70 ±0.16 m/s). The results suggest that the portable device is capable of achieving a good performance according to their values of bias, CV and CNR. The extension of this work is oriented to ex vivo and in vivo experiments. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. -
PublicaciónA preliminary checklist of polypores of Peru, with notes on distribution in the Andes-Amazon region and new records for the country(Guizhou Academy of Agricultural Sciences, 2012)
;Salvador-Montoya, CA ;Millan, B ;Janovec, JPDrechsler-Santos, ERA checklist of 33 polypore species (Hymenochaetales and Polyporales) from the CamantiMarcapata Biological Corridor (CMBC) of Cusco, Peru, is provided with data about distribution in the Andes-Amazon region. More than 90% of polypore species reported herein are new records to the country.