New approach to determine the morphological and structural changes in the enamel as consequence of dental bleaching

Nowadays, there are a number of methods very effectives for the dental bleaching, which are typically strong oxidizing agents, as the hydrogen peroxide, applied directly to the tooth surface. After bleaching, several research studies have been carried out to evaluate the efficacy of bleaching agents on teeth, there being a great controversy concerning the techniques used and their pre-treatment requirements derived, which could alter the final results. In fact, there is a strong necessity to develop different approach to determine the real consequences of bleaching treatment by using an unchangeable and entire tooth. Herein, to evaluate the effects of 38% (p/v) hydrogen peroxide treatment onto morphological, chemical and structural features in the human enamel and dentin, environmental scanning electron microscopy, electron probe micro analyzer and X-ray diffraction techniques have been used. Although such effects have been widely investigated with several techniques, including XRD and SEM, the novelty of this study lies on the techniques and methodology used to characterize the human teeth after bleaching treatment. This approach allows carrying out the analyses without any previous pretreatment, such as powdering, dried or metal sputtering, and its study in the same tooth piece before and after bleaching, which avoids the possible intrinsic differences derived from the use of different pieces. The obtained results display that neither the structural nor the chemical features of both enamel and dentin are altered after bleaching treatment. However, the morphology of the enamel is notably altered, appearing pronounced pores which could affect to the possible bacterial colonization. These findings put an end to the controversies on the different obtained results in the literature of the bleaching effects in the enamel and set standards for future studies

Global kinematics study of OH masers in W49N

Star formation is underway in the W49N molecular cloud (MC) at a high level of efficiency, with almost twenty ultra-compact (UC) HII regions observed thus far, indicating a recent formation of massive stars. Previous works have suggested that this cloud is undergoing a global contraction. We analyse the data on OH masers in the molecular cloud W49N, observed with the VLBA at the 1612, 1665, and 1667 MHz transitions in LCP and RCP with an aim to study the global kinematics of the masers. We carried out our study based on the locations and observed velocities of the maser spots. The velocities were fitted to the straight line of V$_{obs}$-V$_{sys}$ versus d$_{(\alpha, \delta)m}$, resulting in V$_{ftd}$. The difference between the fitted values and those obtained from observations is $\Delta$V. The V$_{obs}$-V$_{sys}$ velocity shows a gradient as a function of the distance to ($\alpha, \delta$)$_{m}$, where the closer spots have the largest velocities. Spots with similar velocities are located in different sectors, with respect to ($\alpha, \delta$)$_{m}$. Then, we assumed that the spots are moving towards a contraction centre (CC$_{OH}$), which is at the apex of a CONUS. We also assumed that the distance of each spot to CC$_{OH}$ is d$_{cc}$ and that they fall with a velocity V$_{CC}$, with the total velocity being V$_{Tot}$. Using this velocity, we estimated the free-fall velocity. The observed dispersion with respect to the global trend against $d_{cc}$, shows a maximum at 0.12 pc, with a decay from 0.12 to 0.19 pc, which is faster than that taking place between 0.19 and 0.42 pc. Based on $V_{tot}$ an inner mass of M$_{inn}$=2500 $M_{\odot}$ was estimated.The velocities of the OH spots at W49N, together with their positions respect $(\alpha, \delta)_m$, make it possible to trace a global kinematics, which seems to be due to a subcollapse in the W49N molecular cloud.Comment: 21 pages, 10 figure

Social Cognitive Theory and Health Care: Analysis and Evaluation

Social Cognitive Theory explains how different personal, environmental and cognitive factors influence human behavior and it has been an important source of knowledge in the social and health sciences. It has been employed in research and practice in nursing, the science of caring. However, no critical analysis has been conducted to show the impact of Social Cognitive Theory in nursing. This article aims to conduct an analysis and evaluation of Social Cognitive Theory using the Fawcett and DeSanto-Madeya methodological framework and a systematic search of the literature. Social Cognitive Theory showed that even though is a non-disciplinary theory of health sciences, the clarity and simplicity of its content facilitates its use in understanding and addressing different phenomena of caring, the creation of middle-range theories and in professional education. The contribution of Social Cognitive Theory in nursing science has focused mainly on two aspects: firstly, on improving disciplinary knowledge with the practical context of health caring by understanding human behavior and its integration in interventions for the promotion, prevention and treatment of health, and secondly, on nursing professionals’ education, highlighting the relevance of the interdisciplinary nature of knowledge

Changes with age (from 0 to 37 D) in tibiae bone mineralization, chemical composition and structural organization in broiler chickens

Broiler chickens have an extreme physiology (rapid growth rates) that challenges the correct bone mineralization, being an interesting animal model for studying the development of bone pathologies. This work studies in detail how the mineralization, chemistry, and structural organization of tibiae bone in broiler chickens change with age during the first 5 wk (37 D) from hatching until acquiring the final weight for slaughter. During the early growth phase (first 2 wk), the rapid addition of bone tissue does not allow for bone organic matrix to fully mineralize and mature, and seems to be a critical period for bone development at which bone mineralization cannot keep pace with the rapid growth of bones. The low degree of bone mineralization and large porosity of cortical bone at this period might be responsible of leg deformation and/or other skeletal abnormalities commonly observed in these birds. Later, cortical bone porosity gradually decreases and the cortical bone became fully mineralized (65%) at 37 D of age. At the same time, bone mineral acquires the composition of mature bone tissue (decreased amount of carbonate, higher crystallinity, Ca/P = 1.68)

Estabilidad política, terrorismo y medios de comunicación. Un análisis de la incidencia de percepciones mediáticas en el turismo receptivo.

The present research seeks to analyze the existing relationship between terrorist attacks, political instability, discourse from international media outlets and news agencies in receptive tourism. To accomplish this, four countries that have different internal situations will be studied in the period 2012- 2015: Egypt, Tunisia, Venezuela and Spain combining quantitative methodologies using official data from international and national organisms, with journalistic discourse analysis from 4 international news agencies and 4 international media outlets through the use of the MAXQDA (v. 11.0.11) software tool. The results have shown that the information spread by media about terrorist attacks have more effects on tourism than those about political and economic instability

Applied methodology based on HEC-HMS for reservoir filling estimation due to soil erosion

Authors propose a beneficial methodology for hydrological planning in their study. Prospective evaluations of the basins' net capacity can be done using the technique presented. The HEC-HMS (Hydrologic Modelling System) software can be used to estimate in a basin, the sediment emitted. For a certain precipitation, this methodology allows estimating, within a certain range, the gradual blockage of a reservoir, and even a projected date for total blockage. This has some applications to adopt corrective measures that prevent or delay the planned blockage deadlines. The model is of the semi-distributed type, estimating the generation and emission of sediments by sub-basins. The integration of different return periods in HEC-HMS with a semi-distributed model by sub-basins and the application of a mathematical model are the differentiating element of this research. The novelty of this work is to allow prognosing the reservoir sedimentation rate of basins in a local and regional scale with a medium and large temporary framework. The developed methodology allows public institutions to take decisions concerning hydrological planning. It has been applied to the case of "Charco Redondo"reservoir, in Cádiz, Andalusia, in southern Spain. Applying the methodology to this case, an average soil degradation of the reservoir basin has been estimated. Therefore, it is verified that in 50 years the reservoir is expected to lose 8.4% of its capacity

Estabilidad política, terrorismo y medios de comunicación. Un análisis de la incidencia de percepciones mediáticas en el turismo receptivo.

The present research seeks to analyze the existing relationship between terrorist attacks, political instability, discourse from international media outlets and news agencies in receptive tourism. To accomplish this, four countries that have different internal situations will be studied in the period 2012- 2015: Egypt, Tunisia, Venezuela and Spain combining quantitative methodologies using official data from international and national organisms, with journalistic discourse analysis from 4 international news agencies and 4 international media outlets through the use of the MAXQDA (v. 11.0.11) software tool. The results have shown that the information spread by media about terrorist attacks have more effects on tourism than those about political and economic instability