Electrodynamic formulation of special relativity from the first postulate

This work presents the form that the special theory of relativity takes when only the first postulate and the properties of homogeneity and isotropy of space and time are considered valid. The transformations of Lorentz coordinates are obtained in terms of a universal constant parameter k, developing from these the relativistic kinematics, dynamics and electrodynamics and their respective invariances before these transformations

Thermodynamic analysis of Kerr-Newman black holes

In this paper we calculate the Hawking temperature of a black hole described by the Kerr-Newman metric, starting from the surface gravity, the area of the event horizon and the angular velocity of the black hole. To do this we apply the laws of black hole thermodynamics: we first set the energy conservation through a relationship between the mass M, the charge Q and the angular momentum J, then we implement the Hawking's theorem of areas by setting an upper bound to the energy and we get finally the surface gravity of the black hole. In addition, we study the relationship between the black hole parameters (mass M, angular momentum J, electric charge Q) and the Hawking temperature

Influence of Ag+ and Mn2+ ions on structural, optical and photoluminescence features of ZnS quantum dots

The current study deals with the structural, morphological, elemental, optical and photoluminescence behaviors of Ag+, Mn2+ dual doped ZnS quantum dots (QDs). The X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) studies confirmed the cubic structure and size of the crystallites (~2 nm). The Scanning Electron Microscope (SEM) photographs portrayed the surface and morphological structure of prepared samples. Energy dispersive X-ray (EDX) and Fourier Transform Infrared Spectra (FTIR) ensured the presence of Zn, Ag, Mn and, S in the samples as per the anticipated stoichiometry ratio. The UV–visible spectra showed a red shift in optical absorption and band gap gets narrowed due to the incorporation of Ag+ ions. The size effect has overcome the quantum confinement effect in this case. Through photoluminescence (PL) studies, a weak UV emission and strong red wavelength emissions were received and discussed on the basis of sulfur vacancies. This red emission was dealt in terms of d-electrons transition between host and dopant ions

Electric consumption pattern from big data

From the concept of smart grid, reaching an efficient and reliable network is a task that implies several stages and sub-stages with a defined and specific mission. In this way, the intelligent measurement stage conformed by the smart meters obtains the information of electrical consumption from the users or consumers (residential, commercial, and industrial). For this purpose, a smart metering infrastructure made of wireless telecommunications and fiber optic has been generated allows to guarantee the connectivity of the smart meters and the central office of electric companies. This paper aims to describe the use of MapReduce as a technique to obtain information about the load curve at an appropriate time to obtain trends and statistics related to the pattern of residential electricity consumption

Forecast of operational data in electric energy plants using adaptive algorithm

Traditional time series methods offer models whose parameters remain constant over time. However, industrial supply and demand processes require timely decisions based on a dynamic reality. A change in configuration, turning off, or on a production line or process, modifies the problem and the variables to be predicted. Decision support systems must dynamically adapt in order to respond quickly and appropriately to operations and their processes. This methodology is based on obtaining, for each period, the model that best fits the data, evaluating many alternatives and using statistical learning techniques. In this way, the model will adapt to the data in practice and make decisions based on experience. With three months of testing for the estimation of variables associated with supply and demand processes, predictions that differ less than 8 hundredths (less than 0.08) or 0.1% of the measured value were obtained. This indicates that data science and statistical learning represent an important area of research for variable prediction and process optimization

Compilation of a social network lexicon for determining the profile of authors

The use of social networks is steadily increasing worldwide. Hundreds of users daily register in the different existing platforms, therefore, the content extracted from the social networks is fundamental for tasks such as sentiment analysis, detection of author profiles, identification of authors, opinions mining, plagiarism detection, calculation of similarity between texts and to develop robust systems that help to make decisions in related areas such as politics, education, economy, among others. This paper provides a lexical aid for the pre-processing of texts posted in social networks evolved for the subsequent languages: English, Spanish, Dutch and Italian

Cómo minimizar los cambios radiológicos laterales en la osteotomía valguizante de adición medial de rodilla

Objetivo: estudiar la relación entre posición del injerto en Osteotomía Valguizante de Adición (OVA) en rodilla, los cambios radiológicos experimentados por la rótula y la pendiente tibial y su correlación clínica. Material y métodos: estudio retrospectivo de 10 pacientes operados de OVA. Medimos el cambio experimentado tras la osteotomía en Índice de Catón y la pendiente tibial y su relación con la ubicación del injerto. Valoración clínica mediante test de Lisholm y WOMAC. Resultados: edad media de 49.5 años, seguimiento medio de 32,2 meses. Se observa un cambio estadísticamente significativo de 1,45º en la pendiente tibial y de 0,15 unidades (Índice Catón) en la altura de la patela, pero sin correlación con la clínica. La ubicación del injerto en el cuadrante posterior se halló en el 80% de los casos. Conclusión : la osteotomía valguizante de adición medial tiene buenos resultados clínicos. Los cambios en la pendiente tibial y en la patela son menores cuanto más posterior es la ubicación del injerto.Objectives: we investigated changes in patellar height and tibial inclination angle after open-wedge high tibial osteotomy, the effect of these changes on patient satisfaction and the correlation with the graft position. Methods: retrospective study of 10 knees who underwent open-wedge proximal tibial osteotomy with allograft and medial plate for medial compartment. Were measured pre- and postoperatively tibial inclination angle, and patellar height (Caton Index), and we study the correlation of these changes with the location of the graft. Clinical evaluations were made using the Lysholm and WOMAC score. Results: the mean age was 49.5 years, the mean follow up was 32,2 months. The mean increase in the tibial inclination angle was 1,45 ° (p<0.05) and the mean of decrease in patellar height was 0.15 Units Caton Index (p<0.05). There weren’t correlation between radiological changes and patients satisfaction. The graft localization was posterior in 80% of patients. Conclusion: the open-wedge tibial osteotomy has good results and high clinical satisfaction. Changes in the tibial slope and the patellar height are lower if the graft position is posterior

Clinical–pathologic significance of cancer stem cell marker expression in familial breast cancers

Human breast cancer cells with a CD44(+)/CD24(−/low) or ALDH1+ phenotype have been demonstrated to be enriched for cancer stem cells (CSCs) using in vitro and in vivo techniques. The aim of this study was to determine the association between CD44(+)/CD24(−/low) and ALDH1 expression with clinical–pathologic tumor characteristics, tumor molecular subtype, and survival in a well characterized collection of familial breast cancer cases. 364 familial breast cancers from the Ontario Familial Breast Cancer Registry (58 BRCA1-associated, 64 BRCA2-associated, and 242 familial non-BRCA1/2 cancers) were studied. Each tumor had a centralized pathology review performed. TMA sections of all tumors were analyzed for the expression of ER, PR, HER2, CK5, CK14, EGFR, CD44, CD24, and ALDH1. The Chi square test or Fisher’s exact test was used to analyze the marker associations with clinical–pathologic tumor variables, molecular subtype and genetic subtype. Analyses of the association of overall survival (OS) with marker status were conducted using Kaplan–Meier plots and log-rank tests. The CD44(+)/CD24(−/low) and ALDH1+ phenotypes were identified in 16% and 15% of the familial breast cancer cases, respectively, and associated with high-tumor grade, a high-mitotic count, and component features of the medullary type of breast cancer. CD44(+)/CD24(−/low) and ALDH1 expression in this series were further associated with the basal-like molecular subtype and the CD44(+)/CD24(−/low) phenotype was independently associated with BRCA1 mutational status. The currently accepted breast CSCs markers are present in a minority of familial breast cancers. Whereas the presence of these markers is correlated with several poor prognostic features and the basal-like subtype of breast cancer, they do not predict OS

Reinforced concrete deterioration caused by contaminated construction water: An overview

Over the years, there were cases of building failures in most developing countries of the world that have led to the loss of lives and property. Yet, most investigations conducted on the causes of building failures have suggested poor design, inadequate supervision, and the use of inferior materials as the factors responsible for the failures. However, not so much emphasis has been placed on concrete mixing water as a contributing factor to the failures. Therefore, this review summarizes the effect of the type and composition of mixing water on the properties of concrete. Different sources of water that can be used to mix concrete were explored, alongside with the effect on fresh and hardened properties of concrete. The fresh properties of concrete, such as setting time and slump, were examined, while the hardened properties focused on the strength and durability of the concrete. A brief statement on the available regulation and standards for mixing water was also reported. This review shows the viability of using water from different sources, such as wastewater, to mix concrete successfully. However, the treatment of some types of water might be required to ensure that excellent strength and durability properties are achieved while preventing any threat to human life and the environment. Area for future research was also suggested, which, among other procedures, could help proffer solutions to the challenge of building failures in developing countries