188 research outputs found
Effective portals to heavy neutral leptons
The existence of right-handed neutrinos, or heavy neutral leptons (HNLs), is strongly motivated by the observation of neutrino masses and mixing. The mass of these new particles could lie below the electroweak scale, making them accessible to low-energy laboratory experiments. Additional new physics at high energies can mediate new interactions between the Standard Model particles and HNLs, and is most conveniently parametrized by the neutrino Standard Model Effective Field Theory, or νSMEFT for short. In this work, we consider the dimension six νSMEFT operators involving one HNL field in the mass range of O (1) MeV < MN < O (100) GeV. By recasting existing experimental limits on the production and decay of new light particles, we constrain the Wilson coefficients and new physics scale of each operator as a function of the HNL mass.1The authors would like to thank the Instituto de Física Teórica (IFT UAM-CSIC) in Madrid for support via the Centro de Excelencia Severo Ochoa Program under Grant CEX2020-001007-S, during the Extended Workshop “Neutrino Theories”, where this work developed. The research of MH was supported by Perimeter Institute for Theoretical Physics. Research at Perimeter Institute is supported by the Government of Canada through the Department of Innovation, Science and Economic Development and by the Province of Ontario through the Ministry of Research, Innovation and Science. JLP acknowledges support from Generalitat Valenciana through the plan GenT program (CIDEGENT/2018/019) and from the Spanish Ministerio de Ciencia e Innovacion through the project PID2020-113644GB-I00. EFM and MGL were also supported by the Spanish Research Agency (Agencia Estatal de Investigación) through the grant PID2019-108892RB-I00 funded by MCIN/AEI/ 10.13039/501100011033. EFM, MGL, and JLP also acknowledge support from European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreements No 860881-HIDDeN and No 101086085- ASYMMETRY. JHG warmly thanks the hospitality of Albert de Roeck and the EP Neutrino group during his stay at CERN; where this project has been completed PID2019-108892RB-I0
Strength Training Prior to Endurance Exercise: Impact on the Neuromuscular System, Endurance Performance and Cardiorespiratory Responses
This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise
Multiscale modelling approach for simulating low velocity impact tests of aramid-epoxy composite with nanofillers
The addition of nanofillers to composites has attracted great attention since it adds multifunctional potential. However, the presence of nanofillers inside a composite may cause a more complex response in many situations, e.g. damage accumulation processes, and this response poses extra challenges in the development of reliable numerical approaches. In this work, a three-step multiscale modelling strategy was used to investigate the mechanical properties and damage accumulation of plain-weave aramid-epoxy composites with hybrid nanofillers (carbon nanotubes and graphene nanoplatelets). First, the mean-field method was employed in a microscale model to provide the elastic modulus of the matrix with nanofillers inside. The mechanical properties of such a matrix were then used to predict the global mechanical properties of aramid-epoxy composite using mesoscale models. Finally, those predictions were added as input to a homogeneous material model used to replicate a more complex loading condition (low-velocity tests), for which the direct use of the mesoscale approach is not feasible. In the latter, the mechanical properties of aramid-epoxy composite with nanofillers have been modelled using MAT_162 in LS-DYNA. The agreement between the experiments and simulations with regards to the loading curves and damage phenomena can thus validate the presented approach. In addition, the effect of nanofillers on the mechanical properties and damage evolution of the woven composites in low-velocity impact has been discussed. Finally, the present work can be helpful to improve the awareness in the design of innovative materials by means of predictive modelling approaches
EcoClimate: a database of climate data from multiple models for past, present, and future for macroecologists and biogeographers
Studies in biogeography and macroecology have been increasing massively since climate and biodiversity databases became easily accessible. Climate simulations for past, present, and future have enabled macroecologists and biogeographers to combine data on species’ occurrences with detailed information on climatic conditions through time to predict biological responses across large spatial and temporal scales. Here we present and describe ecoClimate, a free and open data repository developed to serve useful climate data to macroecologists and biogeographers. ecoClimate arose from the need for climate layers with which to build ecological niche models and test macroecological and biogeographic hypotheses in the past, present, and future. ecoClimate offers a suite of processed, multi-temporal climate data sets from the most recent multi-model ensembles developed by the Coupled Modeling Intercomparison Projects (CMIP5) and Paleoclimate Modeling Intercomparison Projects (PMIP3) across past, present, and future time frames, at global extents and 0.5° spatial resolution, in convenient formats for analysis and manipulation. A priority of ecoClimate is consistency across these diverse data, but retaining information on uncertainties among model predictions. The ecoClimate research group intends to maintain the web repository updated continuously as new model outputs become available, as well as software that makes our workflows broadly accessible
Estrategia de optimización para la síntesis dimensional de un robot paralelo 5R para una aplicación de mesa de corte
Planar robots can perform industrial tasks such as CNC X-Y cutter. Among them, the 5R two-degrees-of-freedom (2-DoF) planar parallel robot can become a useful conceptual design. Parallel robots are made of several closed kinematic chains, which gives them a structure enabling to bear more payload. These robots present the advantages of better load/size capacity, speed, rigidity and precision, while their main drawback is the limited workspace. The paper aim to design the 5R-2DoF parallel robot so that its reachable workspace will be maximum and also with optimal dexterity. In this sense, we take advantage of the Genetic Algorithms (GA) in order to develop an approach for optimal design of the robot. The paper shows a path to follow to design the robot taking into account a maximum workspace with dexterity. We present two study cases to test the performance of the proposed approach.Los robot planos pueden realizar tareas industriales como el corte X-Y. En este sentido, el robot paralelo plano de 2 Grados de Libertad (GdL) y 5 pares de revoluta (R) puede ser empleado como concepto de diseño. Un robot paralelo está conformado por varias cadenas cinemáticas cerradas, lo que le da una estructura que permite una mejor distribución de las cargas soportadas. Los robots paralelos presumen características ventajosas en cuanto a la relación peso del robot y peso de la carga soportada, tienen mayor velocidad, rigidez y precisión. Como principal contrapartida, los robots paralelos tienen un espacio de trabajo reducido. En este trabajo, se busca diseñar un robot plano de 2GdL 5R de forma tal que su espacio de trabajo sea el máximo posible y que además presente óptima destreza. Para ello, se toma ventaja de la técnica de optimización Algoritmos Genéticos (AG) y se desarrolla un procedimiento numérico para optimizar el espacio de trabajo y la agilidad con que el robot puede moverse (destreza). Dos casos de estudio ejemplifican la implementación del procedimiento propuesto
Estrategia de optimización para la síntesis dimensional de un robot paralelo 5R para una aplicación de mesa de corte
Planar robots can perform industrial tasks such as CNC X-Y cutter. Among them, the 5R two-degrees-of-freedom (2-DoF) planar parallel robot can become a useful conceptual design. Parallel robots are made of several closed kinematic chains, which gives them a structure enabling to bear more payload. These robots present the advantages of better load/size capacity, speed, rigidity and precision, while their main drawback is the limited workspace. The paper aim to design the 5R-2DoF parallel robot so that its reachable workspace will be maximum and also with optimal dexterity. In this sense, we take advantage of the Genetic Algorithms (GA) in order to develop an approach for optimal design of the robot. The paper shows a path to follow to design the robot taking into account a maximum workspace with dexterity. We present two study cases to test the performance of the proposed approach.Los robot planos pueden realizar tareas industriales como el corte X-Y. En este sentido, el robot paralelo plano de 2 Grados de Libertad (GdL) y 5 pares de revoluta (R) puede ser empleado como concepto de diseño. Un robot paralelo está conformado por varias cadenas cinemáticas cerradas, lo que le da una estructura que permite una mejor distribución de las cargas soportadas. Los robots paralelos presumen características ventajosas en cuanto a la relación peso del robot y peso de la carga soportada, tienen mayor velocidad, rigidez y precisión. Como principal contrapartida, los robots paralelos tienen un espacio de trabajo reducido. En este trabajo, se busca diseñar un robot plano de 2GdL 5R de forma tal que su espacio de trabajo sea el máximo posible y que además presente óptima destreza. Para ello, se toma ventaja de la técnica de optimización Algoritmos Genéticos (AG) y se desarrolla un procedimiento numérico para optimizar el espacio de trabajo y la agilidad con que el robot puede moverse (destreza). Dos casos de estudio ejemplifican la implementación del procedimiento propuesto
Development of a Mobile Application for Blood Donation Management
The creation of an application that deals with blood donation in order to facilitate knowledge about the act to its users, whether they are donors or not. Although the blood donation rate in Brazil is stable, there is always a search for ways to increase this incentive for donors to stay at or improve this level. Through a qualitative research, it was determined a knowledge of possible donors, their characteristics and limitations to donate and the benefits presented to both, the patient and the donor. The prototype presents the registration screen, information about benefits and general information about updating the registration, scheduling possible donations and how the process works. It has been found that most people have a certain fear about donating blood, as they are unaware of how the process works, and are supposed to cause some kind of harm to their body
Pedagogias Culturais Surdas: educadores surdos refletindo sobre práticas e concepções
Apesar dos mais de duzentos e cinquenta anos de história, a educação de surdos ainda não tem uma tradição de pesquisa sobre o trabalho dos docentes surdos. Atualmente, as experiências que se autodescrevem como abordagens bilíngues nos meios educativos para surdos apontam para uma necessidade de investigação das funções linguística, cultural e pedagógica dos profissionais surdos que atuam nestas instituições. Nesse sentido, apresentamos, por meio deste artigo, um projeto de pesquisa a nível sul-americano recém delineado que procura analisar concepções e práticas pedagógicas culturais surdas provindas de espaços formais e informais em que a comunidade surda circula. O objetivo será atingido a partir da validação de dados coletados em estudos reconhecidos da área sobre o tema e novas coletas por entrevista a fim de mapear práticas pedagógicas ainda não identificadas e reconhecidas, para, logo após, disseminá-las por vários meios, inclusive digitais.</p
Calidad de vida y percepción de apoyo social en personas con HIV en Bogotá, Colombia
En estudios llevados a cabo en paises desarrollados se ha establecido que las personas con HIV/sida refieren tener una menos calidad de vida y menor apoyo social.Objetivo. Explorar la asociacion entre la percepcion del apoyo social afectivo o de personas de confianza y cada dimension de la calidad de vida relacionada con la salud en personas con HIV/sida en Bogota.Materiales y metodos. Se hizo un estudio de corte transversal en personas con HIV/sida seleccionadas por conveniencia, en el marco de un programa de atencion en una red hospitalaria de Bogota. Se utilizaron los cuestionarios de calidad de vida relacionada con la salud SF36 y el cuestionario generico de apoyo social funcional Duke-UNC-11. Se utilizaron modelos de regresion lineal en el analisis.Resultados. Se evidencio una relacion directa entre la dimension del bienestar emocional de la calidad de vida, el apoyo social afectivo (SS=7,36; IC95% 1,04-13,68) y el de personas de confianza (SS=11,63; IC95% 5,30-17,96), asi como entre las dimensiones de la funcion fisica, el desempeno emocional y el dolor corporal y la percepcion del apoyo social de tipo afectivo, y entre el apoyo social de personas de confianza y las dimensiones de la vitalidad y la funcion social. Se encontro una relacion inversa entre los promedios de los puntajes de las dimensiones de desempeno emocional, desempeno fisico y salud general y la percepcion del apoyo social de tipo afectivo con la primera dimension y el de personas de confianza con las dos ultimas.Conclusiones. Los sujetos con una mejor percepcion del apoyo social reportaron una mejor calidad de vida relacionada con la salud, lo cual puede servir de base para la planeacion, el diseno y la implementacion de planes de atencion medica que incorporen variables clinicas, paraclinicas y del entorno del paciente.Introduction: People living with HIV/AIDS in developing countries tend to have a lower quality of life and less social support compared with those in developed countries. Objective: To explore the association between affective social support or social support generating confidence and each dimension of the quality of life related to health among people with HIV/AIDS from Bogota. Materials and methods: We conducted a cross-sectional study of people living with HIV/AIDS using convenience sampling of a care program in a hospital network in Bogota. The quality of life questionnaire SF36 and the generic social support questionnaire Duke-UNC-11 were used, along with linear regression models for the analyses. Results: There was a direct relationship between the emotional well-being dimension of quality of life and the social support systems of affectivity (SS =7. 36; 95% CI: 1. 04; 13. 68) and those generating confidence (SS =11. 63; 95% CI: 5. 30; 17. 96). There was a correlation between the dimensions of physical function, emotional performance, pain, and perceived affective social support. Likewise, we detected relations between the perception of social support generating confidence and the dimensions of vitality and social function. Contrarily, we found an inverse relationship between the averages of the dimension of emotional performance and the perceived affective social support, as well as between the dimension of physical performance and general health with social support generating confidence. Conclusions: Subjects with higher levels of social support had higher levels of quality of life related to health. This finding offers an opportunity for the design and implementation of healthcare plans that incorporate clinical, para-clinical and environmental variables of the patient. Introduccio
Production of bioactive lichen compounds by alginate-immobilized bionts isolated from Cladonia verticillaris: an in vitro study
Bionts isolated from thalli of Cladonia verticillaris, immobilized in calcium alginate, produce two depsidones, fumarprotocetraric and protocetraric acids, and the depside atranorin, that exhibit antimicrobial activity against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae. Organic lichen extract (acetone/ether/chloroform) shows the highest antimicrobial activity due to a possible synergism between these substances. Antioxidant capacity of soluble metabolites secreted from the immobilisates to the bath medium of incubation during the first 12 days of immobilization has been found (˃80% oxidation inhibition). The concentration of soluble phenolic substances depends on the immobilization time (during 32 days), exogenous supply of acetate (1.0m mM sodium or calcium acetate) and on the type of isolated biont (phycobionts, mycobionts, whole thallus or immobilized phycobionts co-incubated with the mycobionts ones).
The role of phycobionts in phenol production has been interpreted as a possible modification of the polymalonyl pathway; for example, atranorin is actively produced and secreted during immobilization while it is not detected in thallus in natura. Co-incubated bionts secrete higher amounts of atranorin to the media during the first 12 days of immobilization. Immobilization of isolated bionts could be used as a biotechnological technique to obtain a potential source of biological active compounds.
On the other hand, the physiological state detected of C. verticillaris in the Cerrado is much better for experimentation than that of the specimens collected in Caatinga since, in this case, the thalli showed the fragility that the extreme environmental conditions of the semi-arid region of NE Brazil impose on this lichen species. To date, no priority has been defined for lichen conservation in Brazilian ecosystems. It is therefore suggested that it imust important to include lichen ecophysiology studies in public conservation policies
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