Intersection problem for Droms RAAGs

We solve the subgroup intersection problem (SIP) for any RAAG G of Droms type (i.e., with defining graph not containing induced squares or paths of length 3): there is an algorithm which, given finite sets of generators for two subgroups H,K of G, decides whether $H \cap K$ is finitely generated or not, and, in the affirmative case, it computes a set of generators for $H \cap K$. Taking advantage of the recursive characterization of Droms groups, the proof consists in separately showing that the solvability of SIP passes through free products, and through direct products with free-abelian groups. We note that most of RAAGs are not Howson, and many (e.g. F_2 x F_2) even have unsolvable SIP.Comment: 33 pages, 12 figures (revised following the referee's suggestions

Predicting Working Memory and Fluid Intelligence from Measures of Musicality

The relationship between musicality and cognitive abilities has been a popular topic in the media and among researchers over the last 25 years. Research has been inconsistent on whether musicality influences performance on non-musical complex tasks, such as measures of working memory and fluid intelligence. Inconsistencies regarding results between studies have arisen partly due to differences in sample and task selection, in addition to conflicting interpretations of results. Consequently, we conducted an individual differences investigation on the prediction of working memory (tonal, verbal, and visuospatial) and fluid intelligence by measures of musicality (formal years of musicality training, musical sophistication, melodic memory, and beat perception). Using correlational and regression approaches, the results showed that individual measures of musicality did not predict performance on each complex cognitive measure uniformly. These results suggest that relationships between musicality and cognitive abilities can be potentially influenced by measurement selection, and musical experiences and abilities underlie cognitive abilities differentially. Further exploration is needed to understand how and why these relationships occurred

Evidence-based Customer Reviews

Online reviews can suffer from certain reliability problems due to reasons such as reviewer bias, lack of reviewer objectivity, insufficient number of reviews, etc. This disclosure describes techniques for generating reviews using evidence gathered from hard data sources rather than from subjective user opinion. Example data sources that can be used to generate evidence-based reviews include IoT sensors internal to the reviewed entity; publicly available information external to the reviewed entity; and data from related reviews applicable to the currently reviewed entity. The evidence-based reviews described herein enable a reader to look beneath the reviews to see the data that led to the review score. The described techniques reduce or eliminate bias in reviews and increase reader confidence in them

Reliable Normalized Customer Reviews

Online reviews suffer from certain reliability problems such as lack of reviewer objectivity, reviewer bias, lack of domain familiarity on the part of the reviewer, etc. This disclosure describes techniques to improve the reliability of review scores obtained from online review facilities. A set of meta-parameters, referred to as review reliability parameters (RRP), is defined and associated with the underlying numerical rating of a review. RRPs are inputs to a machine learning model that derives a weighted review. The review of a reviewer with good RRPs is weighted more than the review of a reviewer with poor RRPs. RRPs can be based on factors such as the reviewer’s domain-specific expertise, history, demographic, meta-reviews, reviewing experience, etc. The techniques enable the creation of reliable, normalized reviews

Self-efficacy, self-esteem and engagement among Peruvian nurses during the COVID-19 pandemic

Introduction: Nursing professionals have faced the COVID-19 pandemic and health crisis on the front lines. Caught without technical and material readiness, as well as without previous experience, they resorted to using their own resources such as self-esteem and self-efficacy to raise their performance and uphold their commitment to public health. It has been reported that one third of the 37,000 nurses working in Peru contracted COVID-19, and approximately 180 died from the virus. Objectives: Measure the influence of personal resources on engagement among professional nurses during the COVID-19 pandemic. Methods: Cross-sectional explanatory correlational research from a sample of 387 Peruvian nursing professionals. A descriptive and inferential statistical analysis was performed. IBM SPSS Statistics V/26 software was used. Results: The results showed highly significant and positive correlations between the variables self-efficacy, self-esteem and engagement. Likewise, predictive values of more than 50% of personal resources on engagement were identified. Conclusions: Professional nurses during the pandemic perceived themselves with an average level of self-efficacy, high levels of self-esteem, and a medium level of engagement. Personal resources, self-efficacy and self-esteem, were able to predict the engagement of professional nurses in the dimensions of vigor, dedication and absorption.Introducción: Los profesionales de enfermería han enfrentado en primera línea la crisis sanitaria de la pandemia producida por la COVID 19. Fueron sorprendidos sin una preparación técnica, material y de conocimientos por lo cual recurrieron a sus propios recursos como la autoestima y la autoeficacia para elevar su desempeño y compromiso con la salud pública. En el Perú se reportó que, durante los dos primeros años de la pandemia, de 37 mil profesionales de enfermería, casi un 1/3 contrajeron el virus y aproximadamente, 180 fallecieron a causa de la Covid-19. Objetivos: Medir el efecto de la autoestima y la autoeficacia sobre el compromiso engagement en profesionales de enfermería durante la pandemia de la Covid-19. Métodos: Investigación Explicativa Correlacional de corte transversal, en una muestra de 387 profesionales de enfermería peruanos. Se hizo un análisis estadístico descriptivo e inferencial de correlaciones y regresiones. Se usó el software SPSS26. Resultados: Los resultados mostraron correlaciones positivas y altamente significativas entre las variables, autoeficacia, autoestima y compromiso (engagement). Así mismo se identificó valores de predictibilidad superior al 50%, sobre el compromiso (engagement). Conclusiones: Los profesionales de enfermería durante la pandemia se percibieron con un nivel de autoeficacia promedio, altos niveles de autoestima y un nivel de compromiso medio (engagement). Los recursos personales, autoeficacia y autoestima, lograron predecir el compromiso (engagement) de los profesionales de enfermería en las dimensiones de vigor, dedicación y absorción

Self-efficacy, self-esteem and engagement among Peruvian nurses during the COVID-19 pandemic

Introduction: Nursing professionals have faced the COVID-19 pandemic and health crisis on the front lines. Caught without technical and material readiness, as well as without previous experience, they resorted to using their own resources such as self-esteem and self-efficacy to raise their performance and uphold their commitment to public health. It has been reported that one third of the 37,000 nurses working in Peru contracted COVID-19, and approximately 180 died from the virus. Objectives: Measure the influence of personal resources on engagement among professional nurses during the COVID-19 pandemic. Methods: Cross-sectional explanatory correlational research from a sample of 387 Peruvian nursing professionals. A descriptive and inferential statistical analysis was performed. IBM SPSS Statistics V/26 software was used. Results: The results showed highly significant and positive correlations between the variables self-efficacy, self-esteem and engagement. Likewise, predictive values of more than 50% of personal resources on engagement were identified. Conclusions: Professional nurses during the pandemic perceived themselves with an average level of self-efficacy, high levels of self-esteem, and a medium level of engagement. Personal resources, self-efficacy and self-esteem, were able to predict the engagement of professional nurses in the dimensions of vigor, dedication and absorption.Introducción: Los profesionales de enfermería han enfrentado en primera línea la crisis sanitaria de la pandemia producida por la COVID 19. Fueron sorprendidos sin una preparación técnica, material y de conocimientos por lo cual recurrieron a sus propios recursos como la autoestima y la autoeficacia para elevar su desempeño y compromiso con la salud pública. En el Perú se reportó que, durante los dos primeros años de la pandemia, de 37 mil profesionales de enfermería, casi un 1/3 contrajeron el virus y aproximadamente, 180 fallecieron a causa de la Covid-19. Objetivos: Medir el efecto de la autoestima y la autoeficacia sobre el compromiso engagement en profesionales de enfermería durante la pandemia de la Covid-19. Métodos: Investigación Explicativa Correlacional de corte transversal, en una muestra de 387 profesionales de enfermería peruanos. Se hizo un análisis estadístico descriptivo e inferencial de correlaciones y regresiones. Se usó el software SPSS26. Resultados: Los resultados mostraron correlaciones positivas y altamente significativas entre las variables, autoeficacia, autoestima y compromiso (engagement). Así mismo se identificó valores de predictibilidad superior al 50%, sobre el compromiso (engagement). Conclusiones: Los profesionales de enfermería durante la pandemia se percibieron con un nivel de autoeficacia promedio, altos niveles de autoestima y un nivel de compromiso medio (engagement). Los recursos personales, autoeficacia y autoestima, lograron predecir el compromiso (engagement) de los profesionales de enfermería en las dimensiones de vigor, dedicación y absorción

Relative order and spectrum in free and related groups

We consider a natural generalization of the concept of order of an element in a group: an element g ¿ G is said to have order k in a subgroup H (resp., in a coset Hu) of a group G if k is the first strictly positive integer such that gk ¿ H (resp., gk ¿ Hu). We study this notion and its algorithmic properties in the realm of free groups and some related families. Both positive and negative (algorithmic) results emerge in this setting. On the positive side, among other results, we prove that the order of elements, the set of orders (called spectrum), and the set of preorders (i.e., the set of elements of a given order) w.r.t. finitely generated subgroups are always computable in free and free times free-abelian groups. On the negative side, we provide examples of groups and subgroups having essentially any subset of natural numbers as relative spectrum; in particular, non-recursive and even non-recursively enumerable sets of natural numbers. Also, we take advantage of Mikhailova’s construction to see that the spectrum membership problem is unsolvable for direct products of nonabelian free groups.The first named author was partially supported by MINECO grant PID2019-107444GA-I00 and the Basque Government grant IT974-16. The second named author acknowledges partial support from the Spanish Agencia Estatal de Investigación, through grant MTM2017-82740-P (AEI/ FEDER, UE), and also from the Graduate School of Mathematics through the María de Maeztu Programme for Units of Excellence in R&D (MDM-2014-0445). The third named author was partially supported by (Polish) Narodowe Centrum Nauki, grant UMO-2018/31/G/ST1/02681.Peer ReviewedPostprint (author's final draft

Comportamiento mecánico de un concreto adicionando fibra de acero dramix 4d como alternativa de solución en pavimentos rígidos

Actualmente se busca mejorar las características del concreto, el uso de fibra de acero puede incrementar la resistencia y disminuir las fisuras. El objetivo de esta investigación es evaluar la caracterización mecánica del concreto adicionando el 0.5%, 1%, 1.5%, 2% e If-min (indicación mínima del fabricante) de fibra de acero Dramix 4D 80/60 BG y 65/60 BG en un concreto f'c de 280 kg/cm², para ser ensayados a los 7, 14 y 28 días de curado, para analizar su comportamiento mecánico. La metodología utilizada es de tipo aplicada bajo un diseño experimental. Los resultadosde acuerdo a las fibras de acero Dramix 4D, se tiene dos tipos; la primera Dramix 4D 80/60BG, y la segunda es Dramix 4D 65/60BG, para ambas se obtuvo el porcentaje óptimo dando como resultado el 2.0%. De acuerdo para un diseño de f’c= 280 kg/cm²a las fibras de Dramix 4D 80/60BG, aumentó la resistencia a la compresión en un 4.04%, en la resistencia a la flexión aumentó en un 22.31 % y la resistencia a la tracción aumentó un 32.58%. Mientras que las fibras de acero Dramix 4D 65/60BG, aumentó la resistencia a la compresión en un 9.53% y en la resistencia a la flexión aumentó en un 38.48 % y la resistencia a la tracción aumentó un 61.35%. Es por ello se concluye que ambas fibras, desde la dosificación mínima recomendadas por el fabricante se obtienen buenos resultados, demostrando que las fibras son eficaces para reducir grietas o fracturas en el concreto para pavimentos rígidosTesisInfraestructura, Tecnología y Medio Ambient