682 research outputs found
Late Pleistocene South American megafaunal extinctions associated with rise of Fishtail points and human population
In the 1970s, Paul Martin proposed that big game hunters armed with fluted projectile points colonized the Americas and drove the extinction of megafauna. Around fifty years later, the central role of humans in the extinctions is still strongly debated in North American archaeology, but little considered in South America. Here we analyze the temporal dynamic and spatial distribution of South American megafauna and fluted (Fishtail) projectile points to evaluate the role of humans in Pleistocene extinctions. We observe a strong relationship between the temporal density and spatial distribution of megafaunal species stratigraphically associated with humans and Fishtail projectile points, as well as with the fluctuations in human demography. On this basis we propose that the direct effect of human predation was the main factor driving the megafaunal decline, with other secondary, but necessary, co-occurring factors for the collapse of the megafaunal community.Fil: Prates, Luciano Raúl. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Arqueología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Perez, Sergio Ivan. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin
Advances in indoor positioning and indoor navigation
Locating devices in indoor environments has become a key issue for many emerging location-based applications and intelligent spaces in different fields [...]This work was supported by European Union's Horizon 2020 Research and Innovation program under the Marie Sklodowska Curie grant agreement No. 813278 (A-WEAR: A network for dynamic WEarable Applications with pRivacy constraints)
Rapid radiation of humans in South America after the last glacial maximum: A radiocarbon-based study
The early peopling of the Americas has been one of the most hotly contested topics in American anthropology and a research issue that draws archaeologists into a multidisciplinary debate. In South America, although the background data on this issue has increased exponentially in recent decades, the core questions related to the temporal and spatial patterns of the colonization process remain open. In this paper we tackle these questions in the light of the quantitative analysis of a screened radiocarbon database of more than 1600 early dates. We explore the frequency of radiocarbon dates as proxies for assessing population growth; and define a reliable and statistically well supported lower chronological bound (not to the exact date) for the earliest human arrival. Our results suggest that the earliest chronological threshold for the peopling of South America should be between 16,600 and 15,100, with a mean estimated date ~ 15,500 cal BP (post Last Glacial Maximum). Population would have grown until the end of Antarctic Cold Reversal stadial ~12,500 cal BP at the time of the main extinctions of megafauna-, when the increase rate slows, probably as a result of the changes that occurred in the trophic niche of humans.Fil: Prates, Luciano Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Arqueología; ArgentinaFil: Politis, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano; ArgentinaFil: Perez, Sergio Ivan. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin
Stress and strain analysis and induced seismicity in geological gas storage (Yela, Spain)
Geologic gas storage is a sustainable strategy to store energy in underground reservoirs in order to be used under demand. Injection and withdrawal gas operations could trigger induced seismicity according to the tectonic constrains of the reservoir. The study of the active stress/strain fields shows the properties of the fault patterns that can be involved in induced seismicity. In our work, we have determined the strain/stress field in the Yela underground gas storage, an Upper Cretaceous carbonate reservoir located in central Spain. Slickensides on fault planes were measured from Cretaceous, Miocene and Quaternary rocks. Results show a strain field with ey (maximum horizontal shortening) oriented NW-SE. This field was compressional during the early Miocene, switching off to extensional from late Miocene to present-day. Our results suggest that NNW-SSE and NW-SE oriented faults could act as an effective pathway for gas leakage and prone to trigger induced seismicity. Moreover, 141 small earthquakes (Mmax 2.3) were recorded during underground operations in Yela. Peaks of earthquakes appear seasonally from November to February, in coincidence with the injection operations prior to the winter withdrawal. Working at its maximum gas storage volume, earthquake peaks decreased in intensity and magnitude from 2017 to 2021, and show a time lag of 3 months from the month of maximum volume injection to the earthquake occurrenc
Ecodesign of large-scale photovoltaic (PV) systems with multi-objective optimization and Life-Cycle Assessment (LCA)
Because of the increasing demand for the provision of energy worldwide and the numerous damages caused by a major use of fossil sources, the contribution of renewable energies has been increasing significantly in the global energy mix with the aim at moving towards a more sustainable development. In this context, this work aims at the development of a general methodology for designing PV systems based on ecodesign principles and taking into account simultaneously both techno-economic and environmental considerations. In order to evaluate the environmental performance of PV systems, an environmental assessment technique was used based on Life Cycle Assessment (LCA). The environmental model was successfully coupled with the design stage model of a PV grid-connected system (PVGCS). The PVGCS design model was then developed involving the estimation of solar radiation received in a specific geographic location, the calculation of the annual energy generated from the solar radiation received, the characteristics of the different components and the evaluation of the techno-economic criteria through Energy PayBack Time (EPBT) and PayBack Time (PBT). The performance model was then embedded in an outer multi-objective genetic algorithm optimization loop based on a variant of NSGA-II. A set of Pareto solutions was generated representing the optimal trade-off between the objectives considered in the analysis. A multi-variable statistical method (i.e., Principal Componet Analysis, PCA) was then applied to detect and omit redundant objectives that could be left out of the analysis without disturbing the main features of the solution space. Finally, a decision-making tool based on M-TOPSIS was used to select the alternative that provided a better compromise among all the objective functions that have been investigated. The results showed that while the PV modules based on c-Si have a better performance in energy generation, the environmental aspect is what makes them fall to the last positions. TF PV modules present the best trade-off in all scenarios under consideration. A special attention was paid to recycling process of PV module even if there is not yet enough information currently available for all the technologies evaluated. The main cause of this lack of information is the lifetime of PV modules. The data relative to the recycling processes for m-Si and CdTe PV technologies were introduced in the optimization procedure for ecodesign. By considering energy production and EPBT as optimization criteria into a bi-objective optimization cases, the importance of the benefits of PV modules end-of-life management was confirmed. An economic study of the recycling strategy must be investigated in order to have a more comprehensive view for decision making
Multiobjective optimization of large scale photovoltaic (PV) systems design: Technico-economic and life-cycle assessment considerations
Solar energy systems are a source of "clean" energy. Yet, if power generation from photovoltaic (PV) systems is free from fossil fuel use and greenhouse gas (GHG) emissions, a considerable amount of energy is consumed in the manufacturing and transport of the elements of the system. Silicon is currently the most widely used material for solar cell design. In this context, life cycle assessment (LCA) studies play a major role to compare and analyze the environmental impacts of products and services along their life cycle. This work aims at determining a general methodology for designing large scale photovoltaic systems, taking into account both technico-economic and environmental considerations. In this paper, only the environmental issue tackled by Life Cycle Assessment has been implemented to quantify the environmental impacts related to three technology of crystalline silicon for photovoltaic modules (PV) that are monocrystalline, multicrystalline and ribbon silico
Transposable element polymorphisms improve prediction of complex agronomic traits in rice
Acord transformatiu CRUE-CSICKey message: Transposon insertion polymorphisms can improve prediction of complex agronomic traits in rice compared to using SNPs only, especially when accessions to be predicted are less related to the training set. Abstract: Transposon insertion polymorphisms (TIPs) are significant sources of genetic variation. Previous work has shown that TIPs can improve detection of causative loci on agronomic traits in rice. Here, we quantify the fraction of variance explained by single nucleotide polymorphisms (SNPs) compared to TIPs, and we explore whether TIPs can improve prediction of traits when compared to using only SNPs. We used eleven traits of agronomic relevance from by five different rice population groups (Aus, Indica, Aromatic, Japonica, and Admixed), 738 accessions in total. We assess prediction by applying data split validation in two scenarios. In the within-population scenario, we predicted performance of improved Indica varieties using the rest of Indica accessions. In the across population scenario, we predicted all Aromatic and Admixed accessions using the rest of populations. In each scenario, Bayes C and a Bayesian reproducible kernel Hilbert space regression were compared. We find that TIPs can explain an important fraction of total genetic variance and that they also improve genomic prediction. In the across population prediction scenario, TIPs outperformed SNPs in nine out of the eleven traits analyzed. In some traits like leaf senescence or grain width, using TIPs increased predictive correlation by 30-50%. Our results evidence, for the first time, that TIPs genotyping can improve prediction on complex agronomic traits in rice, especially when accessions to be predicted are less related to training accessions
DISEÑO DE UN MODELO 3D DEL PIE HUMANO PARA SIMULACIÓN FEM
ResumenEl análisis por el método de elemento finito es útil para conocer los estados de esfuerzos y deformaciones mecánicas que sufre una estructura bajo ciertas condiciones de carga y restricciones que son asignadas a fin de representar la situación de interés en el análisis de una estructura.En este artículo se presenta la metodología para desarrollar un modelo 3D de elementos finitos correspondiente al pie humano, la finalidad de contar con este modelo es que a través de él se pueda generar investigación competente al área de biomecánica, analizando los diferentes tipos de patologías que se presentan en esta extremidad del cuerpo.Entiéndase este trabajo como la creación de una representación virtual de los huesos, músculos y cartílagos existentes en el pie, así como el ensamble de estos, utilizando software CAD como herramienta de diseño y técnicas de reconstrucción de geometrías descritas en este documento.Palabra(s) Clave(s): Biomecánica, método de elemento finito, modelo 3D, software CAD. AbstractThe analysis by the finite element method is useful to know the states of stresses and mechanical deformations that undergoes a structure under certain load conditions and restrictions that are assigned in order to represent the situation of interest in the analysis of a structure. This article presents the methodology to develop a 3D model of finite elements corresponding to the human foot, the purpose of having this model is that through it can generate competent research in the area of biomechanics, analyzing the different types of pathologies that Present at this extremity of the body. This work is understood as the creation of a virtual representation of the bones, muscles and cartilages in the foot, as well as the assembly of these, using CAD software as design tools and geometry reconstruction techniques described in this document.Keyboards: Biomechanics, finite element method, 3D model, CAD software
Programa para la prevención de ciberadicciones en adolescentes
Introducción: La tecnología ha sufrido un desarrollo exponencial y continúacreciendo. Un mal uso puede tener repercusiones negativas en la salud. Los jóvenes son el grupo que mayor uso hace de dispositivos exponiéndose ariesgos, el mayor de ellos, la adicción, con una pérdida en la capacidad de control. La mejor actuación frente a esta nueva problemática social es la prevención.Objetivo: Diseñar un programa de salud, dirigido a adolescentes, mediante el cual se conciencie de los riesgos de un mal uso de las TIC y prevenga ciberadicciones.Metodología: Se ha realizado una búsqueda bibliográfica recurriendo a bases de datos, plataformas. Con esta información se planeó el programa.Conclusiones: En un mundo cada vez más conectado a internet y con mayor número de adolescentes con adicción al uso de las TIC, el papel de la enfermería es crucial para concienciar sobre los riesgos y promover conductas y hábitos de vida saludables, uso saludable de las nuevas tecnologías y alternativas de ocio sanas.Palabras clave: "adicción", "nuevas tecnologías", "prevención", "jovenes".<br /
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