Probing the Effects of Lorentz-Symmetry Violating Chern-Simons and Ricci-Cotton Terms in Higher Derivative Gravity

The combined effects of the Lorentz-symmetry violating Chern-Simons and Ricci-Cotton actions are investigated for the Einstein-Hilbert gravity in the second order formalism modified by higher derivative terms, and their consequences on the spectrum of excitations are analyzed. We follow the lines of previous works and build up an orthonormal basis of operators that splits the fundamental fields according to their individual degrees of freedom. With this new basis, the attainment of the propagators is remarkably simplified and the identification of the physical and unphysical modes gets a new insight. Our conclusion is that the only tachyon- and ghost-free model is the Einstein-Hilbert action added up by the Chern-Simons term with a time-like vector of the type $v^{\mu} = (\mu,\vec{0})$. Spectral consistency imposes taht the Ricci-Cotton term must be switched off. We then infer that gravity with Lorentz-symmetry violation imposes a drastically different constraint on the background if compared to usual gauge theories whenever conditions for suppression of tachyons and ghosts are required.Comment: 15 pages. It coincides with the version published in Phys. Rev.

The role of entrepreneurship on the foundations of dynamic capabilities

This work investigates the antecedents and consequences of dynamic capabilities using data from Portuguese and Brazilian firms. Specifically the influence of entrepreneurship as an opportunity sensing base, the effect on human resources (HR) capability to reach those opportunities, and finally knowledge management (KM) consequences on firm performance. Using a two-country questionnaire, four organisational capabilities are examined, and the link to value creation is established: entrepreneurship capabilities, knowledge management, human resources management capabilities and strategic decision flexibility. The main objective of this research is the operationalisation of a stream of thought on dynamic capabilities. To analyse our model, we have chosen to apply a path analytic technique. This multivariate analysis methodology is regularly used for empirically examining sets of relationships represented in the form of linear causal models, and allows the direct, indirect and total effects. We present the operationalisation of an aggregate construct in this field thus contributing to develop empirical research of dynamic capabilities. Measures were adapted to reflect dynamic decision making. The results show that dynamic capabilities are a complex set of capacities conjugated in sensing, seizing, and reconfiguring processes. Managerial implications for these two countries are discussed.info:eu-repo/semantics/acceptedVersio

Dynamic properties of clay brick at different strain rates

Investigation of the dynamic properties of construction materials is critical for structural engineering. The strain rate effect influences the properties on most constructions materials. This effect on materials such as concrete or steel has been intensively investigated. However, such studies on masonry materials such as clay bricks cannot be found in the open literature easily. Understanding the strain rate effect on masonry materials is important for proper modelling and design of masonry structures under high velocity impacts or blast loads. This work aims to study the behaviour of clay brick in compression at different strain rates. A Drop Weight Impact Machine will be used on clay brick specimens at different heights and weights introducing different levels of strain rate, ranging from 4 s-1 to 199 s-1. The strain rate effect on the ultimate strength, young’s modulus and strain at ultimate strength will be determined from the experimental results. Empirical relations of dynamic increase factors (DIF) for these material properties will be presented

Influence of temperature and light on total phenolic compounds during natural orange juice storage

Abstract in proceedings of the Fourth International Congress of CiiEM: Health, Well-Being and Ageing in the 21st Century, held at Egas Moniz’ University Campus in Monte de Caparica, Almada, from 3–5 June 2019.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.info:eu-repo/semantics/publishedVersio

A MCDA model for olive oil supplier selection using Macbeth

This work proposes a multi-criteria decision-making approach to select suppliers in the olive oil sector. Besides several performance criteria required to the supplier, olive oil characteristics such as colour, smell, and density, as well as organoleptic tests are used. Hence, the assessment and selection of suppliers assumes a major importance and needs to be done yearly. The process of finding a set of suppliers to choose from involves two sequential stages, namely identification and elimination. The identification stage consists of finding a set of potential suppliers. Then, in the elimination stage, suppliers that are not able to meet the thresholds associated with some technical indicators are disregarded. Thus, only a small set of very promising suppliers need to be assessed. The assessment was performed by resorting to the Macbeth approach, resulting in a ranking. The results obtained were validated through sensitivity and robustness analyses.info:eu-repo/semantics/publishedVersio

Transformational leadership contributions for employee autonomy

The performance of a company is affected by several variables and understanding them and knowing how they work is decisive for management. Therefore, this research aims to address and measure how transformational leadership impacts the employees work. To test the conceptual model, we used survey data from 174 active workers. Data was analyzed using PLS-SEM. Our results reveal that leaders who adopt a Transformational approach allow workers to be more autonomous in their work, the autonomy leverage the existence of efficiency in tasks and processes. Efficiency is also reached through cost savings, which translates into a reduction of unproductive work time. Furthermore, results indicate the mediating effect of efficiency and employee autonomy on the relation between transformational leadership and cost savings and between transformational leadership and unproductive work time.info:eu-repo/semantics/publishedVersio

Infill masonry: simple analytical methods for seismic design

The latest earthquake codes in Europe require the safety assessment of no-structural elements (parapets, masonry wall’s veneer, infill walls, etc.), as their collapse entails risks for people or for the main structure stability. This work made possible th e development of a design method, supported by previous experimental researches by applying cyclic out-of-plane loads to damaged masonry infill in RC frames. Panels tested reproduce Portuguese traditional RC structure construction system and two reinforced solutions were created as innovative solutions. The experimental campaign was carried out in order to determine: masonry properties; out-of-plane panel behaviour with previous in-plane damage; building behaviour subjected to dynamic tests performed in shaking table. Using finite element method to reproduce experimental tests and to broaden the range of samples it was possible to figure out equations according to parametric analysis which was able to reproduce in-plane and out-plane behaviour leading to an estimated load bearing capacity of each model and to determine frame strength and its stiffness. Those equations permit to design or verify the masonry infill panels in RC frames subjected to seismic loads

Behavior of masonry infill panels in RC frames subjected to in plane and out of plane loads

The building envelope in Europe is usually made of masonry walls, with enclosure and infill functions. Masonry walls have a major economical importance and contribute significantly to the building performance. Even if infill walls have no load-bearing function, they contribute significantly to the seismic behavior of buildings. Therefore, their adequate structural performance is needed, avoiding the occurrence of severe in-plane damage, with very large economical losses, and the out-of-plane expulsion, which additionally represents a large risk for human life. Recent earthquake codes in Europe require the safety assessment of non-structural elements (parapets, veneer masonry walls, infill walls, etc.), when their collapse entails risks for people or for the main structure. The Eurocode standards, entering the mandatory stage now, incorporate new requirements to be fulfilled by buildings or their parts. Such is the case of masonry infilled RC frames whose panels, according to Eurocode 8, are explicitly required to withstand the out-of-plane movement induced by earthquakes. Appropriate measures should be taken to avoid brittle failure and premature disintegration of the infill walls, as well as the partial or total out-of-plane collapse of slender masonry panels. This paper presents the experimental work and results achieved by applying cyclic out-ofplane loads to damaged masonry infilled RC frames. The masonry panels were previously damaged by applying an in-plane cyclic load after which the cyclic out-of- plane loads were applied. The frames and panels tested follow the traditional Portuguese RC structure construction system to which different types of reinforcement have been introduced in the panels