Relationship between Polymer Dielectric Constant and Percolation Threshold in Conductive Poly(styrene)-Type Polymer and Carbon Black Composites

Se presenta un criterio fenomenológico para determinar el umbral de percolación en compuestos poliméricos polímero - negro de carbono, en términos de la constante dieléctrica del polímeroSIE

Estimación en cálculo multiplicativo con números decimales

L'estimació en càlcul és una destresa bàsica, útil en la resolució de problemes aritmètics. En aquest article analitzem les dificultats, estratègies i errors en les estimacions de càlculs aritmètics de multiplicació i divisió amb nombres naturals i decimals. Servir una metodologia mixta, quantitativa - qualitativa, recollint dades mitjançant una prova d'estimació, seguida per una fase d'entrevistes. Hi participen 131 estudiants de Magisteri. Entre els resultats, els ítems amb decimals menors que 0,1 són els més difícils; amb decimals menors que 1, més difícils que amb naturals o decimals més grans que 1; i les divisions B (dividend menor que divisor), més difícils que les divisions A (dividend més gran que divisor). A la part qualitativa, amb entrevista semiestructurada, analitzem les estratègies i els errors en estimar. Detectem quatre estratègies bàsiques (primers dígits, substitució, fraccions i algorisme alternatiu) i 15 tipus d'errors (4 a la interpretació, 10 a l'execució i 1 a l'avaluació).Computational estimation is a basic skill, useful in solving arithmetic problems. In this paper, we analyze the difficulties, strategies and errors in computational estimation of multiplications and divisions with natural and decimal numbers. We use a mixed methodology, quantitative and qualitative, collecting data by means of an estimation test, followed by a phase of interviews. Participants in the study were 131 pre-service teachers. Among the results, tasks with decimals less than 0.1 are more difficult than others; tasks with decimals less than 1, more difficult than those with natural or decimals greater than 1; and B divisions (with dividend less than divisor) are more difficult than A divisions (with dividend larger than divisor). Qualitative study shows 3 basic estimation strategies (First digits, fractions, and alternative algorithm) and 15 types of errors (4 in interpretation phase, 10 in computation phase, and 1 in evaluation).La estimación en cálculo es una destreza básica, útil en la resolución de problemas aritméticos. En este artículo analizamos las dificultades, estrategias y errores en las estimaciones de cálculos aritméticos de multiplicación y división con números naturales y decimales. Empleamos una metodología mixta, cuantitativa-cualitativa, recogiendo datos mediante una prueba de estimación, seguida por una fase de entrevistas. Participan 131 estudiantes de Magisterio. Entre los resultados, los ítems con decimales menores que 0,1 son los más difíciles; con decimales menores que 1, más difíciles que con naturales o decimales mayores que 1; y las divisiones B (dividendo menor que divisor), más difíciles que las divisiones A (dividendo mayor que divisor). En la parte cualitativa, con entrevista semiestructurada, analizamos las estrategias y los errores al estimar. Detectamos cuatro estrategias básicas (primeros dígitos, sustitución, fracciones y algoritmo alternativo) y 15 tipos de errores (4 en la interpretación, 10 en la ejecución y 1 en la evaluación)

2b-RAD genotyping for population genomic studies of Chagas disease vectors: Rhodnius ecuadoriensis in Ecuador

Background: Rhodnius ecuadoriensis is the main triatomine vector of Chagas disease, American trypanosomiasis, in Southern Ecuador and Northern Peru. Genomic approaches and next generation sequencing technologies have become powerful tools for investigating population diversity and structure which is a key consideration for vector control. Here we assess the effectiveness of three different 2b restriction site-associated DNA (2b-RAD) genotyping strategies in R. ecuadoriensis to provide sufficient genomic resolution to tease apart microevolutionary processes and undertake some pilot population genomic analyses. Methodology/Principal findings: The 2b-RAD protocol was carried out in-house at a non-specialized laboratory using 20 R. ecuadoriensis adults collected from the central coast and southern Andean region of Ecuador, from June 2006 to July 2013. 2b-RAD sequencing data was performed on an Illumina MiSeq instrument and analyzed with the STACKS de novo pipeline for loci assembly and Single Nucleotide Polymorphism (SNP) discovery. Preliminary population genomic analyses (global AMOVA and Bayesian clustering) were implemented. Our results showed that the 2b-RAD genotyping protocol is effective for R. ecuadoriensis and likely for other triatomine species. However, only BcgI and CspCI restriction enzymes provided a number of markers suitable for population genomic analysis at the read depth we generated. Our preliminary genomic analyses detected a signal of genetic structuring across the study area. Conclusions/Significance: Our findings suggest that 2b-RAD genotyping is both a cost effective and methodologically simple approach for generating high resolution genomic data for Chagas disease vectors with the power to distinguish between different vector populations at epidemiologically relevant scales. As such, 2b-RAD represents a powerful tool in the hands of medical entomologists with limited access to specialized molecular biological equipment. Author summary: Understanding Chagas disease vector (triatomine) population dispersal is key for the design of control measures tailored for the epidemiological situation of a particular region. In Ecuador, Rhodnius ecuadoriensis is a cause of concern for Chagas disease transmission, since it is widely distributed from the central coast to southern Ecuador. Here, a genome-wide sequencing (2b-RAD) approach was performed in 20 specimens from four communities from Manabí (central coast) and Loja (southern) provinces of Ecuador, and the effectiveness of three type IIB restriction enzymes was assessed. The findings of this study show that this genotyping methodology is cost effective in R. ecuadoriensis and likely in other triatomine species. In addition, preliminary population genomic analysis results detected a signal of population structure among geographically distinct communities and genetic variability within communities. As such, 2b-RAD shows significant promise as a relatively low-tech solution for determination of vector population genomics, dynamics, and spread

Effect of Boriding on the Mechanical Properties of AISI 1045 Steel

Efecto en las propiedades mecánicas de un acero borurado 1045.Some mechanical properties of AISI 1045 borided steels were estimated in the present work. The boriding process was carried out by the powder pack method at 950°C with 8 h of treatment. The fatigue strength on borided notched specimens was evaluated with rotating bending tests (R=1) considering a stress concentration factor (Kt) of 2.53. Likewise, the presence of residual stresses in boride layers was established by the XRD technique. The Daimler-Benz Rockwell C test was used, also, to estimate the strength adhesion of the coated system. The results show a decrease in the fatigue strength of AISI borided steels due to the presence of high porosity in the layers. Finally, the Rockwell-C adhesion test showed no coating failure for the boride layer

Persistent Sepsis-Induced Hypotension without Hyperlactatemia: A Distinct Clinical and Physiological Profile within the Spectrum of Septic Shock

Introduction. A subgroup of septic shock patients will never develop hyperlactatemia despite being subjected to a massive circulatory stress. Maintenance of normal lactate levels during septic shock is of great clinical and physiological interest. Our aim was to describe the clinical, hemodynamic, perfusion, and microcirculatory profiles associated to the absence of hyperlactatemia during septic shock resuscitation. Methods. We conducted an observational study in septic shock patients undergoing resuscitation. Serial clinical, hemodynamic, and perfusion parameters were registered. A single sublingual microcirculatory assessment was performed in a subgroup. Patients evolving with versus without hyperlactatemia were compared. Results. 124 septic shock patients were included. Patients without hyperlactatemia exhibited lower severity scores and mortality. They also presented higher platelet counts and required less intensive treatment. Microcirculation was assessed in 45 patients. Patients without hyperlactatemia presented higher PPV and MFI values. Lactate was correlated to several microcirculatory parameters. No difference in systemic flow parameters was observed. Conclusion. Persistent sepsis-induced hypotension without hyperlactatemia is associated with less organ dysfunctions and a very low mortality risk. Patients without hyperlactatemia exhibit less coagulation and microcirculatory derangements despite comparable macrohemodynamics. Our study supports the notion that persistent sepsis-induced hypotension without hyperlactatemia exhibits a distinctive clinical and physiological profile

Personalized Management of Fatigue in Individuals With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Long COVID Using a Smart Digital mHealth Solution: Protocol for a Participatory Design Approach

Fatigue; Myalgic encephalomyelitis/chronic fatigue syndrome; Personalized self-managementFatiga; Encefalomielitis miálgica/síndrome de fatiga crónica; Autogestión personalizadaFatiga; Encefalomielitis miàlgica/síndrome de fatiga crònica; Autogestió personalitzadaBackground: Fatigue is the most common symptom in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID, impacting patients’ quality of life; however, there is currently a lack of evidence-based context-aware tools for fatigue self-management in these populations. Objective: This study aimed to (1) address fatigue in ME/CFS and long COVID through the development of digital mobile health solutions for self-management, (2) predict perceived fatigue severity using real-time data, and (3) assess the feasibility and potential benefits of personalized digital mobile health solutions. Methods: The MyFatigue project adopts a patient-centered approach within the participatory health informatics domain. Patient representatives will be actively involved in decision-making processes. This study combines inductive and deductive research approaches, using qualitative studies to generate new knowledge and quantitative methods to test hypotheses regarding the relationship between factors like physical activity, sleep behaviors, and perceived fatigue in ME/CFS and long COVID. Co-design methods will be used to develop a personalized digital solution for fatigue self-management based on the generated knowledge. Finally, a pilot study will evaluate the feasibility, acceptance, and potential benefits of the digital health solution. Results: The MyFatigue project opened to enrollment in November 2023. Initial results are expected to be published by the end of 2024. Conclusions: This study protocol holds the potential to expand understanding, create personalized self-management approaches, engage stakeholders, and ultimately improve the well-being of individuals with ME/CFS and long COVID.This study received funding from the Spanish Ministry of Science and Innovation (Knowledge Generation Project Grant PID-2021-125528OB-I00), and it was cofunded by the 2020 European Union’s Research and Innovation Funding Program

Use of Artificial Neural Networks in Determining Domestic Violence Predictors

This paper aims to determine the predictors of violence against women by their partners, according to the National Survey of Demography and Health - ENDS - Colombia, 2017 using artificial neural networks. The results indicate that the best forecasting model found is the artificial neural network, perceptron model, multilayer associative memory with a hidden layer of 20 units, through functions of sigmoidal activation and sum of square of the error as error function. The ten main explanatory variables are: respect for human rights of the partner, respect for wishes, love expressed by the partner, a history of domestic violence, engaging in joint decision making, decision of contraceptive use, number of connections (partners) of the respondent, decision-making at the financial level, correction of children behavior, and decisions regarding women's health at home

Algorithm Integration Behavior for Discovering Group Membership Rules

Information exploitation processes use different data mining algorithms for obtaining knowledge patterns from data obtained on the problem domain. One of the assumptions when working with these algorithms is that the complexity of the membership domain of the cases they use does not affect the quality of the obtained results. So, it is important to analyze the behavior of the information exploitation process through the discovery of group membership rules by using clustering and induction algorithms. This research characterizes the complexity of the domains in terms of the pieces of knowledge that describe them and information exploitation processes they seek to discover. The results of the experiments show that, in the case of the process for discovering group membership rules, the quality of the patterns differs depending on the algorithms used in the process and the complexity of the domains to which they are applied

The effect of colostrum source (goat vs. sheep) and timing of the first colostrum feeding (2h vs. 14h after birth) on body weight and immune status of artificially reared newborn lambs

Several factors can affect lamb body weight (BW) and immune status during the first days of life, including colostrum source and timing of the first colostrum feeding. The aim of this study was to evaluate the effects of colostrum source (goat or sheep) and timing of the first colostrum feeding (2 or 14h after birth) on lamb BW and immune status. In this study, 40 lambs were removed from their dams at birth and randomly assigned into 4 groups of 10 lambs each. Lambs were subsequently fed at 2 or 14h after birth with goat or sheep colostrum. Blood samples and BW recording were performed before feeding. Blood plasma was used to measure the immunoglobulin concentration (IgG and IgM), chitotriosidase activity, and complement system activity (total and alternative pathways). In general, no differences in any of the measured variables were observed among the 4 groups, indicating that neither colostrum source nor timing of the first colostrum feeding had an effect on these variables. These findings may improve management on lamb farms that raise animals under artificial conditions, because our results indicate that it is not necessary to feed colostrum to lambs immediately after birth and that goat colostrum may be used to feed newborn lambs