Construct Validity of Likert Scales through Confirmatory Factor Analysis: A Simulation Study Comparing Different Methods of Estimation Based on Pearson and Polychoric Correlations

The widespread use of Pearson correlations and, by extension, the Maximum Likelihood estimation method, does not take into account the measurement properties of Likert scales observed variables when carrying out a construct validity process through Confirmatory Factor Analysis (CFA). This simulation study compares four estimation methods (Maximum Likelihood –ML-, Robust Maximum Likelihood –RML-, Robust Unweighted Least Squares –, RULS) according to two of the assumptions CFA is supposed to fulfil: multivariate normality and, especially, the continuous measurement nature of both latent and observed variables. Goodness of fit is diagnosed by X2 Likelihood Ratio Test and RMSEA indices. Results suggest ULS and RULS are preferable as polychoric correlations help to overcome grouping and transformation errors produced when using Pearson correlations for ordinal observed variables. Data measurement scale consideration enhances the ability of hypothesized models to reproduce accurately construct variables relationships

Construct Validity of Likert Scales through Confirmatory Factor Analysis: A Simulation Study Comparing Different Methods of Estimation Based on Pearson and Polychoric Correlations

The widespread use of Pearson correlations and, by extension, the Maximum Likelihood estimation method, does not take into account the measurement properties of Likert scales observed variables when carrying out a construct validity process through Confirmatory Factor Analysis (CFA). This simulation study compares four estimation methods (Maximum Likelihood –ML-, Robust Maximum Likelihood –RML-, Robust Unweighted Least Squares –, RULS) according to two of the assumptions CFA is supposed to fulfil: multivariate normality and, especially, the continuous measurement nature of both latent and observed variables. Goodness of fit is diagnosed by X2 Likelihood Ratio Test and RMSEA indices. Results suggest ULS and RULS are preferable as polychoric correlations help to overcome grouping and transformation errors produced when using Pearson correlations for ordinal observed variables. Data measurement scale consideration enhances the ability of hypothesized models to reproduce accurately construct variables relationships

Dental implants in patients treated with oral bisphosphonates. A bibliographic review

Bisphosphonates inhibit bone resorption and are used to treat a range of pathologies, including Paget disease, osteoporosis, multiple myeloma and metastases associated with breast or prostate cancer. At present, there is no effective treatment for bisphosphonate induced osteonecrosis, so prevention is extremely important. Since quality of life deteriorates for those suffering osteonecrosis, maximum precautions should be taken with patients at risk, and especially whenever oral surgery, including dental implant placement, is contemplated. Dentists and oral or maxillofacial surgeons must keep up to date with the latest approaches to prevention, particularly when treating patients who are presently taking, or who will be taking bisphosphonates and are also candidates for dental implants

Las Mineralizaciones de Cu de Cabildo, Cordillera de la Costa, Chile central

Este artículo ha sido publicado en la Revista Macla de la Sociedad Española de Mineralogía disponible en: http://www.ehu.eus/sem/macla_pdf/macla9/macla9_165.pdfSe presenta una caracterización de las Mineralizaciones de Cu de Cabildo, Cordillera de la Costa, Chile central, con la presencia de dos tipos de yacimientos: depósitos de Cu de tipo manto chileno (detpósitos de tipo CMT) y skarn.Departamento de Mineralogía y Petrología (Universidad de Granada)Departamento de Didáctica de las Ciencias Experimentales (Universidad de Granada)Este trabajo ha sido realizado en el marco del proyecto CGL2006-02594 (Ministerio de Educación y Ciencia y FEDER). Verónica Moreno agradece al MEC la financiación recibida a través de una beca FPU

miRNAs as radio-response biomarkers for breast cancer stem cells

In breast cancer (BC), the presence of cancer stem cells (CSCs) has been related to relapse, metastasis, and radioresistance. Radiotherapy (RT) is an extended BC treatment, but is not always effective. CSCs have several mechanisms of radioresistance in place, and some miRNAs are involved in the cellular response to ionizing radiation (IR). Here, we studied how IR affects the expression of miRNAs related to stemness in different molecular BC subtypes. Exposition of BC cells to radiation doses of 2, 4, or 6 Gy affected their phenotype, functional characteristics, pluripotency gene expression, and in vivo tumorigenic capacity. This held true for various molecular subtypes of BC cells (classified by ER, PR and HER-2 status), and for BC cells either plated in monolayer, or being in suspension as mammospheres. However, the effect of IR on the expression of eight stemness- and radioresistance-related miRNAs (miR-210, miR-10b, miR-182, miR-142, miR-221, miR-21, miR-93, miR-15b) varied, depending on cell line subpopulation and clinicopathological features of BC patients. Therefore, clinicopathological features and, potentially also, chemotherapy regimen should be both taken into consideration, for determining a potential miRNA signature by liquid biopsy in BC patients treated with RT. Personalized and precision RT dosage regimes could improve the prognosis, treatment, and survival of BC patients.This work has been partially funded by the Consejería de Economía, Conocimiento, Empresas y Universidad de la Junta de Andalucía and European Regional Development Fund (ERDF), ref. SOMM17/6109/ UGR, and with grants from the Ministry of Economy and Competitiveness (FEDER funds, projects no. PIE16/00045) and from the Chair ‘Doctors Galera- Requena in cancer stem cell research’ (CMC-CTS963)

HER2-signaling pathway, JNK and ERKs kinases, and cancer stem-like cells are targets of Bozepinib

Identification of novel anticancer drugs presenting more than one molecular target and efficacy against cancer stem-like cells (CSCs) subpopulations represents a therapeutic need to combat the resistance and the high risk of relapse in patients. In the present work we show how Bozepinib [(RS)-2,6-dichloro-9-[1-(p-nitrobenzenesulfonyl)-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]-9H-purine], a small anti-tumor compound, demonstrated selectivity on cancer cells and showed an inhibitory effect over kinases involved in carcinogenesis, proliferation and angiogenesis. The cytotoxic effects of Bozepinib were observed in both breast and colon cancer cells expressing different receptor patterns. Bozepinib inhibited HER-2 signaling pathway and JNK and ERKs kinases. In addition, Bozepinib has an inhibitory effect on AKT and VEGF together with anti-angiogenic and anti-migratory activities. Moreover, the modulation of pathways involved in tumorigenesis by Bozepinib was also evident in microarrays analysis. Interestingly, Bozepinib inhibited both mamo- and colono-spheres formation and eliminated ALDH+ CSCs subpopulations at a low micromolar range similar to Salinomycin. Bozepinib induced the down-regulation of c-MYC, β-CATENIN and SOX2 proteins and the up-regulation of the GLI-3 hedgehog-signaling repressor. Finally, Bozepinib shows in vivo anti-tumor and anti-metastatic efficacy in xenotransplanted nude mice without presenting sub-acute toxicity. These findings support further studies on the therapeutic potential of Bozepinib in cancer patients.This work was supported in part by grants from the Instituto de Salud Carlos III (Fondo de Investigación Sanitaria, projects nº. PI10/02295, CP08/00063 and PI10/00592) and the ERDF (European Regional Development Fund)

Peer sexual harassment in adolescence: Dimensions of the sexual harassment survey in boys and girls

The phenomenon of adolescent sexual harassment is a topic that has taken on special relevance in recent decades. However, general consensus regarding its nature, prevalence and dimensions has yet to emerge. This study used a representative sample of 3,489 Andalusian adolescents from the second stage of Compulsory Secondary Education (E.S.O.) and the Spanish Baccalaureate (Bachillerato), and it is primarily focused on two main objectives: to test the factor structure of the "sexual harassment" scale in boys and girls, and to analyzethe prevalence of hte sexual harassment among adolescent students. Descriptive analyses andconfirmatory factor analysis (CFA) were performed, allowing us to explore the nature of the phenomenon and to describe its prevalence. The results obtained revealed a two-dimensionalstructure of this scale in both boys and girls: one dimension reflecting visual-verbal forms of sexual harassment and the second dimension including physical forms. Regarding to prevalence,the outcomes shown a high prevalence of sexual harassment involvement across both sexes during adolescence. However, boys were more involved in victimization and aggression than girls. The importance of analyzing the phenomenon in greater depth is also highlighted

Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tetheredballoon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds

Background rejection in NEXT using deep neural networks

[EN] We investigate the potential of using deep learning techniques to reject background events in searches for neutrinoless double beta decay with high pressure xenon time projection chambers capable of detailed track reconstruction. The differences in the topological signatures of background and signal events can be learned by deep neural networks via training over many thousands of events. These networks can then be used to classify further events as signal or background, providing an additional background rejection factor at an acceptable loss of efficiency. The networks trained in this study performed better than previous methods developed based on the use of the same topological signatures by a factor of 1.2 to 1.6, and there is potential for further improvement.The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the Ministerio de Economia y Competitividad of Spain and FEDER under grants CONSOLIDER-Ingenio 2010 CSD2008-0037 (CUP), FIS2014-53371-C04 and the Severo Ochoa Program SEV-2014-0398; GVA under grant PROMETEO/2016/120. Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. JR acknowledges support from a Fulbright Junior Research Award.Renner, J.; Farbin, A.; Muñoz Vidal, J.; Benlloch-Rodríguez, J.; Botas, A.; Ferrario, P.; Gómez-Cadenas, J.... (2017). Background rejection in NEXT using deep neural networks. Journal of Instrumentation. 12. https://doi.org/10.1088/1748-0221/12/01/T01004S1

Confirmatory Factor Analysis of Ordinal Variables: A Simulation Study Comparing the Main Estimation Methods

In order to obtain evidences about construct validity through Confirmatory Factor Analysis, it has been usual treating Likert-type scales as if they were continuous variables measured on an interval scale. Therefore, Maximum Likelihood estimation method has been broadly applied, but in turn it implies problems concerning both Pearson correlations and skewness in the distribution of responses to items. In this simulation study we analyse —through χ2, Type I error, and power— correctly specified and misspecified models comparing five estimation methods (Maximum Likelihood —ml—, Robust Maximum Likelihood —rml—, Weighted Least Squares —wls—, nweighted Least Squares —uls— and Robust Unweighted Least Squares —ruls—) in relation to the models features: number of factors, number of response categories, items’ skewness, and sample size. We advise using ruls estimation method, in which polychoric correlations are implied.Keywords: Confirmatory Factor Analysis, Likert-type scales, estimation methods, Type I error, power.Para obter evidências sobre a validez de constructo através da análise fatorial confirmatória tem  isso habitual tratar as escalas tipo Likert como se fossem variáveis contínuas medidas segundo  ma escala de intervalo.  Portanto, o método de estimação de máxima verossimilitude tem sido amplamente aplicado, mas ao mesmo tempo isto implica problemas em torno às correlações de Pearson e a assimetria da distribuição de respostas aos itens. Neste estudo de simulação analisamos –através de χ2, do erro tipo I e da potência— modelos bem e mau especificados comparando cinco métodos de estimação (máxima verossimilitude —ml—, máxima verossimilitude robusta —rml—, mínimos quadrados ponderados —mls—, mínimos quadrados não ponderados —uls— e mínimos quadrados não ponderados robustos —ruls—) em relação com as características dos modelos: número de fatores, número de categorías de resposta, assimetria dos itens e tamanho amostral. Aconselhamos usar o método ruls de estimação, no qual estão implicadas as correlações policóricas.Palavras-chave: análise fatorial confirmatória, escalas tipo Likert, métodos de estimação, erro tipo I, potência.Para obtener evidencias sobre la validez de constructo a través de Análisis Factorial Confirmatorio, ha sido habitual tratar las escalas tipo Likert como si fueran variables continuas medidas según una escala de intervalo. Por tanto, el método de estimación de Máxima Verosimilitud ha sido  ampliamente aplicado, pero a su vez esto implica problemas en torno a las correlaciones de Pearson y la asimetría de la distribución de respuestas a los ítems. En este estudio de simulación analizamos —a través de χ2, del error tipo I y de la potencia— modelos bien y mal especificados comparando cinco métodos de estimación (Máxima Verosimilitud —ml—, Máxima Verosimilitud Robusta —rml—, Mínimos Cuadrados Ponderados —mls—, Mínimos Cuadrados no Ponderados —uls— y Mínimos Cuadrados no Ponderados Robustos —ruls—) en relación con las características de los modelos: número de factores, número de categorías de respuesta, asimetría de los ítems y tamaño muestral. Aconsejamos usar el método ruls de estimación, en el cual están implicadas las correlaciones policóricas.Palabras clave: análisis Factorial Confirmatorio, escalas tipo Likert, métodos de estimación, error tipo I, potencia