Stabilizing s-hole dimethyl interactions

Methyl groups bound to electronegative atoms, such as N or O, are recognized to participate in tetrel bonding as Lewis acids. On the other hand, the capability of methyl groups bound to electropositive atoms, such as B or Al, to act as Lewis bases has been recently reported. Herein, we analyze the combination of these two behaviors to establish attractive methyl···methyl interactions. We have explored the Cambridge Structural Database to find experimental examples of these dimethyl-bound systems, finding a significant degree of directionality in the relative disposition of the two methyl groups. Moreover, we have carried out a comprehensive computational analysis at the DFT level of the dimethyl interactions, including the natural bond orbital, energy decomposition analysis, and topological analysis of the electron density (QTAIM and NCI). The dimethyl interaction is characterized as weak yet attractive and based on electrostatics, with a non-negligible contribution from orbital charge transfer and polarization

¿Existe un sesgo en la participación y visibilidad de las mujeres en ecología? Una comparación entre los congresos ibérico y suizo

Women are still under-represented in science and technology because there is a bias in the different evaluation processes from the admission of oral communications at conferences to the access to more qualified positions. In this study, we compared the participation and visibility of female ecologists in the IV Iberian Ecological Conference (CIE4) with the Annual Swiss Conference on Ecology, Evolution, Systematics, Biogeography and Conservation (Biology16) where a method of blind evaluation was applied. In both conferences, and after active selection by conference committees, male delegates presented proportionately more regular oral contributions than female ones, although these differences were marginally significant. In the Biology16, this bias was due to lower female applicants for oral contributions, and in the CIE4, to a lower selection rate of female oral contributions. In the CIE4, the higher male presence in oral contributions was consistent with male greater visibility, whereas female visibility was higher in the Biology16. This different visibility was caused by contrasting selection for invited speakers; being male researches preferentially invited at the CIE4, but female ones at the Biology16. Implementing a blind review system of contributions and active policies to promote the participation of women as invited speakers may reduce the differences in visibility and could contribute in the medium term to eliminate the bias against women in the selection of oral contributions at the Iberian conferences

In Vivo and in vitro antitumor activity of tomatine in hepatocellular carcinoma

Background: There is abundant ethnopharmacological evidence the uses of regarding Solanum species as antitumor and anticancer agents. Glycoalkaloids are among the molecules with antiproliferative activity reported in these species. Purpose: To evaluate the anticancer effect of the Solanum glycoalkaloid tomatine in hepatocellular carcinoma (HCC) in vitro (HepG2 cells) and in vivo models. Methods: The resazurin reduction assay was performed to detect the effect of tomatine on cell viability in human HepG2 cell lines. Programmed cell death was investigated by means of cellular apoptosis assays using Annexin V. The expression of cancer related proteins was detected by Western blotting (WB). Reactive oxygen species (ROS) and calcium were determined by 2,7-dichlorodihydrofluorescein diacetate and Fluo-4, respectively. Intrahepatic HepG2 xenograft mouse model was used to elucidate the effect of tomatine on tumor growth in vivo. Results and Discussion: Tomatine reduced HepG2 cell viability and induced the early apoptosis phase of cell death, consistently with caspase-3, -7, Bcl-2 family, and P53 proteins activation. Furthermore, tomatine increased intracellular ROS and cytosolic Ca+2 levels. Moreover, the NSG mouse xenograft model showed that treating mice with tomatine inhibited HepG2 tumor growth. Conclusion: Tomatine inhibits in vitro and in vivo HCC tumorigenesis in part via modulation of p53, Ca+2, and ROS signalling. Thus, the results suggest the potential cancer therapeutic use of tomatine in HCC patients

Higher-order Mechanics: Variational Principles and other topics

After reviewing the Lagrangian-Hamiltonian unified formalism (i.e, the Skinner-Rusk formalism) for higher-order (non-autonomous) dynamical systems, we state a unified geometrical version of the Variational Principles which allows us to derive the Lagrangian and Hamiltonian equations for these kinds of systems. Then, the standard Lagrangian and Hamiltonian formulations of these principles and the corresponding dynamical equations are recovered from this unified framework.Comment: New version of the paper "Variational principles for higher-order dynamical systems", which was presented in the "III Iberoamerican Meeting on Geometry, Mechanics and Control" (Salamanca, 2012). The title is changed. A detailed review is added. Sections containing results about variational principles are enlarged with additional comments, diagrams and summarizing results. Bibliography is update

A review of the engineering properties of metakaolin based concrete: towards combatting chloride attack in coastal/ marine structures

Changing human lifestyle and increasing urbanisation are contributory factors to the high demand for concrete construction materials across the globe. With the imminent developments in the unpopulated marine/coastal zones, higher installation of concrete facilities is still expected. However, poor design and construction procedures coupled with inadequate materials selection and exposure to aggressive environmental conditions, such as chloride laden environments, often result in the reduced aesthetic and structural performance of concrete. Deterioration of reinforced concrete structures located in a coastal/marine setting can influence the safety, economic, and sustainability aspects of society. Hence, there is an increased need for alternate binder systems with the ability to reduce the effects of chloride attack in concrete. 1is paper presents a critical review of the engineering properties of metakaolin (MK) based concrete exposed to chloride attack. 1e key advantages and limitations of using MK for concrete production purposes were outlined and evaluated. Areas for future research were also highlighted in this paper. Based on the favourable 28-day compressive strength (73–84 MPa) and durability performance documented across the numerous past year studies that were reviewed, it can be concluded that MK is a viable alternate binder material for combatting chloride attack in coastal/marine concrete structures. 1is, in conjunction with its lack of chemical CO2 emissions, proves that MK can be used to improve the serviceability and sustainability states of marine structures. 1e viewpoint of this review will guide concrete constructors and researchers on a possible framework for the utilisation of metakaolin for enhancing durability concrete in aggressive environments

Visual behaviour and decision-making in attack situations in volleyball

El objetivo de estudio fue comparar el comportamento visual (número y duración de las fijaciones visuales) y la toma de decisiones (TD) en el análisis de escenas de ataque en voleibol, entre entrenadores y jóvenes jugadores. Participaron 59 sujetos - 34 entrenadores (M=32.5; DT=9.4) con experiencia como jugadores y entrenadores de voleibol (M=16.78; DT=11.09), y 25 jugadores (M=16.9; DT=1) con experiencia como jugadores de voleibol (M=3.72; DT=1.17). Para el análisis de la calidad de la TD se emplearon las escenas de ataque del Test de Conocimiento Táctico Declarativo en Voleibol (TCTD:Vb). Para el análisis del comportamiento visual se utilizó el Eye Tracking SMI RED500® durante el análisis de las escenas. Los resultados muestran diferencias significativas en la duración de las fijaciones siendo mayores en el grupo de los entrenadores. Concluye que existe un patrón similar de comportamiento visual en la comparación entre los grupos únicamente diferenciado por la duración de las fijaciones visualesThe objective of comparing visual behavior (number and duration of visual fixations) and decision-making (DM) in the analysis of attack scenes in volleyball, between coaches and young players. 59 subjects will participate – 34 coaches (M = 16.7, SD = 9.4) with experience as players and volleyball coaches (M = 16.78, SD = 11.09), and 25 players (M = 16.9, SD = 1) with experience as volleyball players (M = 3.72 , SD = 1.17). For the analysis of DM quality, the attack scenes of the Tactical Declarative Knowledge Test in Volleyball (TDKT:Vb) were used. For the analysis of visual behavior, the Eye Tracking SMI RED500® was used during the analysis of the scenes. The results show significant differences in duration of fixations being greater for the coaches group. It concludes that there is a similar pattern of visual behavior in the comparison between groups only differentiated by the duration of the visual fixation

Examen de las compensaciones y precios de suscripción en el mercado de derivados cambiarios chileno

Este trabajo entrega elementos para el entendimiento del funcionamiento del mercado cambiario chileno, haciendo uso de una base de datos única para el período enero 2007-junio 2008, e identifica múltiples características de las suscripciones de contratos forward de monedas. Se expone la evolución de las compensaciones asociadas a los contratos forward distinguiendo agentes y plazos. Asimismo, se examinan las transferencias monetarias asociadas a las compensaciones por diferencias entre los precios de suscripción y la paridad efectiva al momento de vencimiento de los contratos. En este aspecto, las compensaciones generadas por las suscripciones cambiarias fueron positivas para las Administradoras de Fondos de Pensiones (AFP) y negativas para el sector real. También, se comparan los precios de suscripción, tanto de compra como de venta, entregando luces respecto a eventuales discriminaciones de precios por parte de los market-makers. El examen evidencia que no es posible observar diferencias persistentes de discriminación de precios. Finalmente, se examinan los márgenes de intermediación de bancos locales y externos, así como la evolución que estos han experimentado en lo reciente. Para ambos grupos de bancos, estos márgenes se ubican en promedio en torno a los 10 puntos base (pb).

Organizing health care: an ethical perspective

Indexación: Web of Science; Scielo.Health Care at population level is a complex problem. Having this in mind, the purpose of this paper is to focus on the goods that are ethically relevant in the process of caring for health at this level. We briefly analyze some of the Chilean health statistics that, although they show important improvements along the years, demonstrate that certain conditions are to be deemed as inadequate by both healthcare providers and patients. Ethics is a central component to determine how to structure and organize health care systems and how they should operate. We emphasize Human Dignity as an ethical corner stone of the Health Care System, along with other important values such as Justice and Humanization, under the scope of the Ends of Medicine, and other components such as technical competence of providers and the financing of the whole process. We conclude that as far as a health care system is organized in a way that medical practice is well ordered, primarily and fundamentally according the Ends of Medicine and the good of persons, such a health care system is ethically adequate.http://ref.scielo.org/9bt3z

Symmetries in Classical Field Theory

The multisymplectic description of Classical Field Theories is revisited, including its relation with the presymplectic formalism on the space of Cauchy data. Both descriptions allow us to give a complete scheme of classification of infinitesimal symmetries, and to obtain the corresponding conservation laws.Comment: 70S05; 70H33; 55R10; 58A2