When is each proper overring of R an S(Eidenberg)-domain?

A domain R is called a maximal "non-S" subring of a field L if R [containded in] L, R is not an S-domain and each domain T such that R [containded in] T [contained in or equal] L is an S-domain. We show that maximal "non-S" subrings R of a field L are the integrally closed pseudo-valuation domains satisfying dim(R) = 1, dimv(R) = 2 and L = qf(R)

Blind Carrier Phase Recovery for General 2{\pi}/M-rotationally Symmetric Constellations

This paper introduces a novel blind carrier phase recovery estimator for general 2{\Pi}/M-rotationally symmetric constellations. This estimation method is a generalization of the non-data-aided (NDA) nonlinear Phase Metric Method (PMM) estimator already designed for general quadrature amplitude constellations. This unbiased estimator is seen here as a fourth order PMM then generalized to Mth order (Mth PMM) in such manner that it covers general 2{\Pi}/M-rotationally symmetric constellations such as PAM, QAM, PSK. Simulation results demonstrate the good performance of this Mth PMM estimation algorithm against competitive blind phase estimators already published for various modulation systems of practical interest.Comment: 14 pages, 12 figures, International Journal of Wireless & Mobile Networks (IJWMN

Application of electrochemical sensors as an alternative tool for perfume evaluation

Mestrado de dupla diplomação com a Université Libre de TunisThe capability to discriminate perfumes based on their specific aroma profiles is of utmost relevance for the perfume industry considering that, the identification of more than three aromas is a very difficult task even for a trained human nose. Currently, no analytical tool can completely substitute the human nose for aroma evaluation. Also, no analytical system can fully mimic the human perception, being the recognition of perfume aroma patterns usually carried out by gas chromatography coupled with olfactometry or sniffing techniques or even by applying electronic noses, although it still is a difficult analytical task. In this work, the possibility of applying a potentiometric electronic tongue as an analytical sensors tool for perfume analysis, was evaluated for the first time. In fact, the perfume aroma pattern will depend on the composition of the liquid perfume phase and on the diffusion properties of the volatile components, making the proposed strategy feasible from a theoretical point of view. A multi-sensor potentiometric device, comprising a set of 40 lipid sensor membranes with cross-sensitivity, was applied together with chemometric techniques to identify and establish unique chemical perfume fragrances’ fingerprints for discriminating perfumes according to the target consumer (men – women perfumes), the perfume olfactory family (Citric-Aromatic, Floral, Floral-Fruity, Floral-Oriental, Floral-Woody, Woody-Oriental and Woody-Spicy) or the perfume storage time-period (≤ 9 months; 9-24 months; and, ≥ 24 months). Linear discriminant multivariate models were established, based on potentiometric profiles gathered by sub-sets of sensors selected using the simulated annealing algorithm, and allowed correct classification rates of 93-100% (for leave-one-out cross-validation procedure). The satisfactory analytical performance of the electronic tongue demonstrates the versatility of the proposed approach, as a practical device for preliminary perfume classification, which industrial application may be foreseen in a near future, contributing to a green-sustained economic growth of the perfume industry.A capacidade de discriminar perfumes com base em seus perfis de aromas específicos é de extrema relevância para a indústria de perfumes, considerando que a identificação de mais de três aromas é uma tarefa muito difícil, mesmo para um nariz humano treinado. Atualmente, nenhuma ferramenta analítica pode substituir completamente o nariz humano na avaliação do aroma. Além disso, nenhum sistema analítico pode imitar completamente a percepção humana, sendo o reconhecimento de padrões de aroma de perfume geralmente realizados por cromatografia em fase gasosa acoplada a técnicas de olfatometria ou cheirar ou mesmo pela aplicação de narizes eletrónicos, embora ainda seja uma tarefa analítica difícil. Neste trabalho, a possibilidade de aplicar uma língua eletrónica potenciométrica como uma ferramenta analítica de sensores para a análise de perfumes foi avaliada pela primeira vez. De fato, o perfil de aromas do perfume dependerá da composição da fase líquida do perfume e das propriedades de difusão dos componentes voláteis, viabilizando a estratégia proposta do ponto de vista teórico. Um dispositivo potenciométrico de multisensores, com um conjunto de 40 membranas lipídicas com sensibilidade cruzada foi aplicado, em conjunto com técnicas quimiométricas para identificar e estabelecer perfis típicos de fragrâncias químicas para discriminação de perfumes de acordo com o consumidor-alvo (perfumes masculinos - femininos ), a família olfativa do perfume (cítrico-aromático, floral, floral-frutado, floral-oriental, floral-amadeirado, amadeirado-oriental e amadeirado-especiado) ou o período de armazenamento do perfume (≤ 9 meses; 9-24 meses e ≥ 24 meses). Modelos multivariados discriminantes lineares foram estabelecidos, com base em perfis potenciométricos de subconjuntos de sensores selecionados usando o algoritmo de recozimento simulado, e permitiram obter taxas de classificação corretas de 93 a 100% (para a validação cruzada “leave-one-out”). O desempenho analítico satisfatório da língua eletrónica demonstra a versatilidade da abordagem proposta, como um dispositivo prático para a classificação preliminar de perfumes, cuja aplicação industrial pode ser prevista em um futuro próximo, contribuindo para um crescimento económico sustentado da indústria de perfume

Stakeholder approach, Stakeholders mental model: A visualization test with cognitive mapping technique

The idea of this paper is to determine the mental models of actors in the firm with respect to the stakeholder approach of corporate governance. The use of the cognitive map to view these diagrams to show the ways of thinking and conceptualization of the stakeholder approach. The paper takes a corporate governance perspective, discusses stakeholder model. It takes also a cognitive mapping technique

Pullbacks and universal catenarity

This paper deals with the universal catenarity of a pullback construction ring. It seeks necessary and sufficient conditions for such a pullback to have the universal catenarity, improving some known results. Its main result leads to new examples of universally catenarian domains

A COGNITIVE APPROACH TO CORPORATE GOVERNANCE: A VISUALIZATION TEST OF MENTAL MODELS WITH THE COGNITIVE MAPPING TECHNIQUE

The idea of this paper is to determine the mental models of actors in the fi rm with respect to the cognitive approach of corporate governance. The paper takes a corporate governance perspective, discusses mental models and uses the cognitive map to view the diagrams showing the ways of thinking and the conceptualization of the cognitive approach. In addition, it employs a cognitive mapping technique. Returning to the systematic exploration of grids for each actor, it concludes that there is a balance of concepts expressing their cognitive orientation

Impact of COVID19 on the Islamic cryptocurrencies

Cryptocurrency is a new form of digital asset based on a network distributed across a large number of computers. The main objective of this work is to investigate the impact of COVID-19 on the Islamic cryptocurrency markets returns. In this methodology, we identify a group of Islamic cryptocurrencies consisting of the X8X, Hellogold and OneGram. This paper uses the Newey-West standard errors regression to estimate the effect of the COVID-19 pandemic on the Islamic cryptocurrencies returns. The empirical results show that COVID-19 total deaths have a negative effect on respectively the X8X cryptocurrency, HelloGold, and OneGram cryptocurrencies. In the same way, the COVID-19 total confirmed cases growth has a negative effect on respectively the X8X cryptocurrency, and OneGram cryptocurrencies. This study contributes to the literature by identifying the impact of COVID-19 on the Islamic cryptocurrency markets

Islamic view towards Bitcoin

This paper proposes to analyze the agent behavior by means of big data extracted from the search engine « Google trends » and Twitter API to visualize the emotions and the manner of thinking about « Bitcoin » in the Islamic context. Two kinds of sentiment measures are constructed. The first is based on the search query of the word « Bitcoin » with religious connotation all over the world from 14/04/2017 to 14/04/2018 in weekly frequency. The second is built on twitter data from 03/04/2018 to 13/04/2018, by using a Bayesian machine learning device exploiting deep natural language processing modules to assign emotions and sentiment orientations. In the next step, the Granger causality analysis is used to investigate the hypothesis that this sentiment causes the volatility and the returns of « Bitcoin ». The results show that, at a first-level that twitter users of the word « Islamic Bitcoin » improve positive sentiment. Secondly, the Twitter sentiment measure has a significant effect on lagged Bitcoin returns and volatility. Furthermore, this sentimental variable Granger causes Bitcoin returns and volatility.  This study contributes to the literature by studying the influence of the doctrinal view towards Bitcoin on his prices dynamics. Knowing that Bitcoin is a new financial asset and there is a large debate on his compliance with sharia

Stakeholder Approach Stakeholders Mental Model a Visualization Test with Cognitive Mapping Technique

The idea of this paper is to determine the mental models of actors in the firm with respect to the stakeholder approach of corporate governance. The use of the cognitive map to view these diagrams to show the ways of thinking and conceptualization of the stakeholder approach.The paper takes a corporate governance perspective, discusses stakeholder model. It takes also a cognitive mapping technique