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Using a nonparametric item response theory model to identify patterns of cognitive decline: The Mokken scale analysis
No full textCognitive decline, particularly in dementia, presents complex challenges in early detection and diagnosis. While Item Response Theory (IRT) has been instrumental in identifying patterns of cognitive impairment through psychometric tests, its parametric models often require large sample sizes and strict assumptions. This creates a need for more adaptable, less demanding analytical methods. This study aimed to evaluate the effectiveness of Mokken scale analysis (MSA), a nonparametric IRT model, in identifying hierarchical patterns of cognitive impairment from psychometric tests. Using data from 1164 adults over 60 years old, we applied MSA to the orientation subscale of ACE-III. Our analysis involved calculating scalability, monotone homogeneity, invariant item ordering (IIO) and response functions. The MSA effectively retrieved the hierarchical order of cognitive impairment patterns. Most items showed strong scalability and consistent patterns of cognitive performance. However, challenges with IIO were observed, particularly with items having adjacent difficulty parameters. The findings highlight MSA's potential as a practical alternative to parametric IRT models in cognitive impairment research. Its ability to provide valuable insights into patterns of cognitive deterioration, coupled with less stringent requirements, makes it a useful tool for clinicians and researchers
An Exponentiated Skew-Elliptic Nonlinear Extension to the Log-Linear Birnbaum-Saunders Model with Diagnostic and Residual Analysis
No full textIn this paper, we propose a nonlinear regression model with exponentiated skew-elliptical errors distributed, which can be fitted to datasets with high levels of asymmetry and kurtosis. Maximum likelihood estimation procedures in finite samples are discussed and the information matrix is deduced. We carried out a diagnosis of the influence for the nonlinear model. To analyze the sensitivity of the maximum likelihood estimators of the model's parameters to small perturbations in distribution assumptions and parameter estimation, we studied the perturbation schemes, the case weight, and the explanatory and response variables of perturbations; we also carried out a residual analysis of the deviance components. Simulation studies were performed to assess some properties of the estimators, showing the good performance of the proposed estimation procedure in finite samples. Finally, an application to a real dataset is presented
Solastalgia and rural depopulation in contexts of forced displacement due to the open-pit mining
No full textThe expansion of open pit mining in Latin America has generated processes of rural depopulation, evidenced demographically in population and housing censuses. However, there is little research on this. The objective was to analyze the socio demographic changes in communities affected by forced displacement linked to open pit mining. Qualitative methods were used to collect information in the field, and quantitative methods to compare census indicators between 1990 and 2020. Salaverna, a town located in Zacatecas, Mexico, which is going through an experience of forced displacement, is studied. The results show that companies promote the displacement of entire towns with the premise of improving the living conditions of the population to extract minerals with a sustainable approach. However, those are usually carried out involuntarily in contexts of unequal power over capacities, interests and needs of the population. The forced displacement changes the people's way of life and generates feelings of solastalgia due to the anguish of socio -environmental devastation and the gradual destruction of towns that, for local inhabitants, can represent the center of their world
Psychometric properties of Addenbrooke’s Cognitive Examination III (ACE-III): An item response theory approach.
No full textThe Addenbrooke's Cognitive Examination III is one of the most widely used tests to assess cognitive impairment. Although previous studies have shown adequate levels of diagnostic utility to detect severe impairment, it has not shown sensitivity to detect mild decline. The aim of this study was to evaluate the psychometric properties of Addenbrooke's Cognitive Examination III in a large sample of elderly people through Item Response Theory, due to the lack of studies using this approach. A cross-sectional study was conducted with 1164 people from the age of 60 upwards, of which 63 had a prior diagnosis of Alzheimer dementia. The results showed that, globally, the Addenbrooke's Cognitive Examination III possesses adequate psychometrics properties. Furthermore, the information function test shows that the subscales have different sensitivity to different levels of impairment. These results can contribute to determining patterns of cognitive deterioration for the adequate detection of different levels of dementia. An optimized version is suggested which may be an economic alternative in the applied field
Free Fatty Acid Receptor 1 Signaling Contributes to Migration, MMP-9 Activity, and Expression of IL-8 Induced by Linoleic Acid in HaCaT Cells
No full textKeratinocytes and neutrophils are the main cellular components in wound healing during re-epithelization and inflammation. Free fatty acids such as linoleic acid (LA) present beneficial properties for wound healing by modulating the inflammatory response. LA is a natural ligand of free fatty acids receptor 1 (FFA1), a G protein-coupled receptor (GPCR), able to modulate inflammatory process; however, the role of FFA1 in keratinocytes and wound healing remains poorly understood. In this study, we investigated the role of FFA1 signaling in migration, matrix metalloproteinase-9 (MMP-9) activity, and IL-8 expression induced by LA in keratinocytes. We confirmed that HaCaT cells, a human keratinocyte cell line, expresses the FFA1 receptor and GW1100, a selective antagonist of FFA1, decreased LA-induced migration of HaCaT cells. Also, GW9508, a synthetic agonist of FFA1, increased migration of these cells. Furthermore, ERK1/2 and p38 MAPK inhibitors abolished the LA-induced increase in cell migration. Besides, HaCaT cells stimulated with LA or GW9508 increased the activity of MMP-9 and the expression of IL-8. GW1100 partially inhibited both responses. We further evaluated the effects of HaCaT cells conditioned media stimulated with LA or GW9508 on neutrophil chemotaxis. Conditioned media induced neutrophil chemotaxis. Furthermore, IL-8 secreted by HaCaT cells stimulated with LA or GW9508, contributed to neutrophil chemotaxis. In conclusion, LA increased migration, MMP-9 activity, and expression of IL-8 from HaCaT cells via FFA1. Hence, these results showed that the effects induced by LA in keratinocytes can be mediated through FFA1, thus explaining a possible mechanism by which this fatty acid could accelerate wound healing
Distribution of<i> Boeckella</i><i> poppei</i> (Mrazek, 1901) (Copepoda: Calanoida) on the Livingston Island, Maritime Antarctic
No full textThe available data on the localities (including new localities) of the calanoid copepod Boeckella poppei on the Livingston Island, Maritime Antarctic, are summarised. The results suggest a substantial expansion in the distribution of the species, likely owing to recent climate change and the resulting freeing from permanent ice or snow of additional territories during the austral summer
Macrolichen Communities Depend on Phorophyte in Conguillio National Park, Chile
No full textThe community composition of epiphytic macrolichens from two tree species (Araucaria araucana and Nothofagus antarctica) was conducted in temperate forests in the Conguillio National Park, Chile. The composition of lichen biota is influenced by phorophyte species, bark pH, and microclimatic conditions. A total of 31 species of macrolichens were found on A. araucana and N. antarctica. Most of the species showed phorophyte preference, with nine being exclusive to A. araucana and 10 to N. antarctica. The detrended correspondence analysis (DCA) indicated the formation of three communities: one representing macrolichens growing on N. antarctica and two others growing chiefly on A. araucana, either with north or south exposure. More work is needed to study the lichen biota of the forests of the Chilean Andes, which are under multiple threats, including clearing and climate change. In order to counteract such risks to native forests and to the biodiversity of the associated epiphytic lichens, conservation plans should be established that consider the factors that influence the composition of the lichen community
Psychometric Properties of the SV-RES60 Resilience Scale in a Sample of Chilean Elementary School Teachers
No full textThe concept of resilience, identified as a crucial variable due to its association with several beneficial outcomes in adulthood, is of particular interest in the teaching field. Specifically, teachers work in a demanding, challenging, and stressful context that requires a remarkable ability to adapt; therefore, resilience is important in the field of teaching and training, as it plays a fundamental role in children's cognitive, social, and emotional development. This study sought to analyze the psychometric properties of the SV-RES60 Resilience Scale in a sample of Chilean elementary school teachers from first to eighth grade (N = 1406; mean age = 41.4; SD = 10.8). ESEM and bifactor ESEM analyses were performed to evaluate its factor structure, internal consistency, and reliability. The results supported a bifactor structure in which resilience was represented by one general latent factor and twelve specific factors (RMSEA = 0.032; 90%CI [0.030, 0.033]; SRMR = 0.012; CFI = 0.986; TLI = 0.977). A predominance of the unidimensional components of the SV-RES60 (general factor, ECV = 0.812; & omega;h = 0.975) and a high reliability (& alpha; = 0.981; & omega; of the general factor = 0.991) were observed. In conclusion, the SV-RES60 Resilience Scale is a suitable instrument for measuring the general factor of resilience in the investigated teaching environment. Future studies could contribute towards evidence of a reduced scale and transcultural validation to conduct comparative studies
Effects of<i> Aurantiochytrium</i><i> acetophilum</i> as a source of docosahexaenoic acid for juvenile Atlantic salmon<i> (Salmo</i><i> salar)</i> on growth, nutrient apparent digestibility, tissue fatty acid composition and expression of lipid metabolism-related genes
No full textThraustochytrids are a group of unicellular marine protists that are noted for their ability to produce high amounts of lipids, especially docosahexaenoic acid (DHA), making them a valuable source for replacing fish oil in aquafeeds. Varying levels of Aurantiochrytrium acetophilum meal (TM) were evaluated as replacement of fish oil in extruded diets for juvenile Atlantic salmon on growth, nutrient apparent digestibility, fatty acid composition in muscle and liver and expression of genes associated with lipid metabolism. Four experimental diets were tested: a control diet without the inclusion of A. acetophilum meal and three experimental diets derived from the control diet, in which fish oil was progressively replaced by the addition of A. acetophilum meal at 2.5% (TM 2.5), 6.5% (TM 6.5) and 12% (TM 12) respectively. After 12 weeks of feeding, the growth, feed conversion, condition factor and survival of the fish were not affected by the inclusion of A. acetophilum in the diet. However, the 12% inclusion significantly decreased the viscerosomatic index of the fish and the digestibility of protein, lipids, ash and energy compared to the other experimental diets. The lipid content and fatty acid profile of the liver and muscle were significantly affected by diet composition. In both tissues, fish fed the TM 12 diet retained the highest levels of DHA. However, it was also observed that EPA concentrations lessened with increasing dietary content of A. acetophilum meal. Finally, the decrease in the expression of Delta 5fad in the fish fed with the TM 6.5 and TM 12 diets showed that fish do not require a higher expression of this desaturase for DHA production, due to the high content of this fatty acid in A. acetophilum meal
Stabilization of black cotton soil using coconut fiber
Get PDFBlack cotton soil is a soil with low bearing capacity, swelling and shrinkage characteristics. Due to its peculiar characteristics, it forms a very poor foundation material. As black cotton soil is an expansive soil; it creates problem for lightly loaded structure than moderately loaded structure. Through this project, we are trying to study the improvements in the properties of soil by adding coconut fiber of varying percentages. Tests will be conducted to determine liquid limit and unconfined compression strength. Stabilization of soil is an effective method for improving the properties of soil. It has great significance in the future projectsEl suelo de algodón negro es un suelo con baja capacidad de carga, características de hinchamiento y contracción. Por sus características peculiares, forma un material de cimentación muy pobre. Como el suelo de algodón negro es un suelo expansivo; crea un problema para la estructura con una carga ligera que la estructura con una carga moderada. A través de este proyecto, estamos tratando de estudiar las mejoras en las propiedades del suelo agregando fibra de coco en diferentes porcentajes. Se realizarán pruebas para determinar el límite de líquido y la resistencia a la compresión no confinada. La estabilización del suelo es un método eficaz para mejorar las propiedades del suelo. Tiene una gran trascendencia en los proyectos futuros