Application of the Renormalization Group in the study of the metallic transport properties and the superconducting state under magnetic field in organic conductors

Abstract : This thesis tackles the problem of the possible phase transitions in the presence of a magnetic field, and of the transport properties of quasi-one-dimensional (quasi-1D) superconductors like Bechgaard salts. In the framework of the quasi-1D electron-gas model, the renormalization group (RG) method is used for studying the effect of Zeeman coupling to a magnetic field on the structure of the phase diagram of the quasi-1D electron gas model. For the transport theory, a combination of linearized Boltzmann equation and renormalization group method is used to investigate the electrical resistivity and the Seebeck coefficient of quasi-1D correlated organic metals like the Bechgaard salts near their quantum critical point that joins antiferromagnetism and superconductivity. The thesis is organized in four chapters. In the first chapter, an introduction to the Bechgaard and Fabre salts is given and properties of their generic temperature-pressure phase diagram are explained. These compounds are considered as the reference systems for the comparison between theory and experiments on the nature and symmetry of the superconducting phase in a magnetic field and the anomalous transport properties in the normal phase. The problem of the observed anomalously high value of the upper critical field of Bechgaard salts is the main issue of chapter two. We approach this problem with the aid of the weak coupling renormalization group technique in the presence of Zeeman coupling, for an extended quasi-1D electron-gas model, which includes inter-chain hopping, nesting deviations along with both intrachain and inter-chain repulsive interactions. This allows us to study the efect of quasi-1D spin fluctuations originating from constructive interference between unconventional superconductivity (SC) and density-wave instabilities on the magnetic field vs temperature phase diagram of these quasi-1D superconductors. Our results support the existence of a crossover from d-wave to an inhomogeneous d-wave FFLO superconducting state under field. In the third chapter, we introduce the semi-classical Boltzmann equation for transport in its linearized form. The Boltzmann theory is coupled to the RG method for the calculation of the renormalized umklapp scattering amplitude for the anisotropic scattering time. We then study the temperature and pressure variation of the electrical resistivity and the Seebeck coefficient of the Bechgaard salts quasi-one-dimensional organic superconductors in the quantum critical domain of their normal phase. We demonstrate that momentum and temperature dependence of umklapp scattering strongly affects the temperature behavior of transport in the metallic state, as a function of nesting deviations that simulate the influence of pressure in the actual phase diagram. This defines a characteristic quantum critical region where significant deviations from the Fermi-liquid behavior are seen, either as an anomalous power law of electrical resistivity or sign reversal of the Seebeck coefficient.Cette thèse aborde le problème des transitions de phase possibles, en présence d'un champ magnétique, et des propriétés de transport dans des supraconducteurs quasi-unidimensionnels (quasi-1D) comme les sels de Bechgaard. Dans le cadre du modèle d'un gaz d'électrons quasi-1D, on utilise la méthode du groupe de renormalisation (GR) pour étudier l'effet du couplage Zeeman sur le diagramme de phase ce système. Pour la théorie du transport, une combinaison de l'équation de Boltzmann linéarisée et de la méthode de groupe de renormalisation est utilisée pour étudier la résistivité électrique et le coefficient de Seebeck de métaux organiques comme les sels de Bechgaard au voisinage de leur point critique quantique joignant l'antiferromagnétisme et la supraconductivité. La thèse est organisée en quatre chapitres. Dans le chapitre un, une introduction aux sels de Bechgaard et de Fabre est donnée et les propriétés de leur diagramme de phase générique en température-pression sont expliquées. Ces composés sont considérés comme des systèmes de référence pour la comparaison entre la théorie et les expériences sur la nature et la symétrie de la phase supraconductrice sous un champ magnétique et les propriétés anormales de transport dans la phase normale. Le problème de la valeur anormalement élevée du champ critique supérieur observée dans les sels de Bechgaard est la question principale traitée au chapitre deux. Nous abordons ce problème à l'aide de la technique de couplage faible du groupe de renormalisation, pour le modèle du gaz d'électrons quasi-1D étendu, qui contient le saut inter-chaînes, les déviations par rapport à l'emboitement parfait, ainsi que les interactions intra-chaînes et inter-chaînes répulsives. Ceci nous permet d'étudier l'effet des fluctuations de spin quasi-1D provenant d'une interférence constructive entre la supraconductivité non conventionnelle (SC) et les instabilités d'onde de densité sur le diagramme de phase en champ magnétique et en température de ces supraconducteurs quasi-1D. Grâce à notre approche, nous examinons les instabilités possibles dans la partie basse température/champ élevé du diagramme de phase. Dans le troisième chapitre, nous introduisons l'équation semi-classique de Boltzmann pour le transport dans sa forme linéarisée. La théorie de Boltzmann est couplée à la méthode du GR pour le calcul de l'amplitude de diffusion umklapp renormalisée entrant dans l'évaluation du temps de diffusion anisotrope. Nous étudions ensuite la variation en température et en pression de la résistivité électrique et le coefficient de Seebeck pour les supraconducteurs organiques quasi-1D, les sels de Bechgaard, dans le domaine critique quantique de leur phase métallique. Nous démontrons que la variation en quantité du mouvement et en température de la diffusion umklapp sur la surface de Fermi affecte fortement le comportement thermique du transport dans l'état métallique, en fonction des déviations à l'emboîtement parfait. Dans notre modèle, ces déviations simulent l'influence de la pression dans le diagramme de phase réel. Ceci définit une région critique quantique caractéristique où des écarts significatifs par rapport au comportement du liquide de Fermi sont observés, soit comme une loi de puissance anormale de la résistivité électrique, soit comme un changement de signe du coefficient de Seebeck

Information Communication Technology for Crisis Management and Shared Situational Awareness: Social Media Public Health Communication During the COVID-19 Pandemic

This comprehensive study analyzes the role of social media, specifically Facebook, in crisis communication during the COVID-19 pandemic. Conducted through a longitudinal netnography approach, the research scrutinizes the communication strategies of Australian public health agencies from 2019 to 2020 and their impact on shared situational awareness (SSA). Drawing on the Seppänen et al. (2013) model for crisis communication, the study looks at three key aspects - link content (information), link type (communication), and link quality (trust) - and evaluates how they influence SSA during a crisis. The application of Chaos Theory further enhances the research's depth by identifying patterns and transformations in Facebook communications before and after the COVID-19 disruption. The study reveals that the pandemic significantly disrupted typical health communication strategies, leading to new emergent patterns, and it also underscores the critical role of secondary communication and emotional factors in the public's decision to share crisis information. Moreover, it identifies issues such as misinformation and inconsistency in messaging as significant obstacles to the public's trust in official health communications, ultimately impeding the creation of adequate SSA. The research emphasizes the need to develop consistent, clear, and reliable messaging strategies for effective crisis communication. The findings expand existing knowledge on social media utilization in crisis communication, offering valuable insights to enhance public health agencies' communication strategies, thereby aiding in the creation of trusted SSA. Unlike prior studies focusing on crisis response teams, this research concentrates on shared situational awareness among the general public, providing practical recommendations to improve social media crisis communication for more effective response and management in a health crisis

Follicular development and the expression of BAX and vascular endothelial growth factor in transplanted ovaries in uni- and bilateral ovariectomized mice: An experimental study

Background: Several conflicting results have been reported on the survival and function of transplanted ovaries. Objective: Evaluation of the follicular development and the expression of vascular endothelial growth factor (VEGF) and Bcl-2-associated X protein (BAX) in ovaries transplanted into uni- and bilaterally ovariectomized mice. Materials and Methods: In this experimental study, 40 female NMRI mice (21-days-old, 12-15 gr) were ovariectomized uni- and bilaterally (n = 20/ group), while the 8-wk-old mice were considered as intact control group (n = 6). 5 weeks after transplantation at the proestrus stage, the morphology of recovered transplanted ovaries and the proportion of follicles were studied at different developmental stages. The apoptosis cell death by pro-apoptotic protein BAX and the expression of VEGF were evaluated using immunohistochemistry. Results: In the bilaterally ovariectomized mice, among the 455 counted normal follicles, a lower rate of primordial and primary follicles and a higher rate of preantral and antral follicles were observed (p = 0.002). However, the percentages of preantral and antral follicles, and the corpus luteum were significantly lower in the intact control group (among the 508 counted normal follicles in this group) compared to other transplanted groups (p = 0.002). The number of BAX-positive cells in all groups was not significantly different. The VEGF expression was prominent in vessels of the corpus luteum, and also in the theca layer of large follicles of studied groups. Conclusion: Early discharge of ovarian reserve was prominent in the bilaterally ovariectomized group but the incidence of apoptotic cells and VEGF expression as angiogenic factor did not differ in both ovariectomized mice. Thus, unilaterally ovariectomy has less side effects on the ovarian reserve compared to bilateral ovariectomy. Key words: Autotransplantation, BAX protein, Vascular endothelial growth factor, Ovariectomy, Mice

Knowledge Architecture Framework based on Zachmans Enterprise Architecture Framework

During the last fifteen years, knowledge management has changed through new perspectives and enhancements from generation to generation. Numerous researchers have presented research methodologies, frameworks and technologies and have discussed various theoretical and practical knowledge management issues. However, knowledge management is still in need of improvement and has not yet reached its maturity. This paper assesses the common research grounds between knowledge management and Zachmans enterprise architecture framework. Applied research is carried out using descriptive surveys. Information was gathered by using questionnaires filled out by knowledge management and enterprise architecture experts. Finally, a knowledge architecture framework was designed according to Zachmans framework

Evaluating Lighting Condition of Primary Schools in 2015 (Case Study:Nahavand City of Hamadan Province, Iran)

The quality of vision is essential that universally understood about the human condition in a learning environment. In this regard, lighting exceeds than standard level increased visual fatigue as reflection decrease by eye blinks. Against exposure to lower maximum allowed to involve Nystagmus, headaches and impaired vision as the most significant symptoms for students. Therefore, this study aimed to evaluate the total lighting condition (a combination of natural and artificial lighting) in primary schools in Nahavand city and compared it with the international standards. This study investigated average lighting using illumination meter DX200 INS in Nahavand’s primary schools. Results showed that mean lighting for whole classrooms was 415.7±166 lux. Also, ratio of window area/floor area (WA/FA) was less than the standard ratio only in 8 classes from 121 totals with the coefficient of correlation 0.56 between illuminances average and ratio of WA/FA. These findings might have practical implications for the implementation of desirable and standard lighting in schools for better practice of students

Estimativa da composição elementar de solos do Azerbaijão oeste, Irã, utilizando-se modelos espectrais de infravermelho

[Abstract] Characterizing the elemental composition provides useful information about the weathering degree of soils. In Miandoab County, Northern Iran, this characterization was missing, and thus the objectives of this work were to evaluate the weathering degrees for the most typical soils in the area from their elemental compositions, and to estimate this elemental composition using Fourier transform infrared spectroscopy and Random Forest models. Five soil profiles, including Aridisols and Inceptisols, were selected as the most representative of the area. Major elemental oxides were determined in each genetic horizon by X-ray fluorescence, showing that these soils were at early developmental stages. Only Al2O3 and CaO were accurately estimated, with R2 values of 0.8, and out-of-bag mean square errors of 0.2 and 1.1, respectively. The other oxides were not predicted satisfactorily, probably due to small differences in their elemental compositions. Random Forest provided the important spectral bands related to the content of each element. For Al2O3, these bands were between 500 and 650 cm-1, which represent out-of-plane OH bending vibrations and Al-O gibbsite and alumino-silicate vibrations. For CaO, the most important bands are related to carbonate content. A combination of Fourier transform infrared spectra and Random Forest models can be used as a rapid and low-cost technique to estimate the elemental composition of arid and semi-arid soils of Northern Iran.[Resumo] A caracterização da composição elementar fornece informações úteis para caracterizar o grau de alteração dos solos. Em Miandoab, norte do Irã, esta caracterização não existe. Os objetivos deste trabalho foram avaliar o grau de intemperismo dos solos típicos da região usando a sua composição elementar e estimar esta composição usando espectroscopia infravermelha com transformada de Fourier (FTIR) e modelos Random Forest (RF). Foram selecionados cinco perfis de solo, incluindo Aridisolos e Inceptisolos, como os mais representativos da área. Os principais óxidos elementares foram determinados por fluorescência de raios-X em cada horizonte genético, mostrando que estes solos estavam em um estágio de baixo grau de desenvolvimento. Apenas o Al2O3 e o CaO foram estimados com precisão, com valores de R2 de 0,8 e erro quadrático médio nos dados utilizados para validação de 0,2 e 1,1, respectivamente, enquanto os outros óxidos não foram preditos satisfatoriamente, provavelmente devido às pequenas diferenças na sua composição. O modelo Random Forest forneceu importantes bandas espectrais relacionadas com o conteúdo de cada elemento. Para o Al2O3, estes atingiram a região 500 a 650 cm-1, o que foi atribuído a vibrações de flexão de OH e vibrações de Al-O de gibbsita e alumino-silicatos. Para o CaO, as bandas mais importantes estavam relacionadas ao teor de carbonatos. Os resultados indicam que uma combinação de espectros infravermelha de transformada de Fourier e modelos Random Forest pode ser usada como uma técnica rápida e de baixo custo para estimar a composição elementar de solos do norte do Irã

Policymaking for Applying the Approach of Bring Your Own Device in COVID-19 Pandemic: A Perspective

By beginning of the year 2020, COVID-19 has spread all over the world. The virus has caused numerous social, medical, and political challenges. One of the major challenges faced by countries to control the outbreak of the virus was the stability of economic and social activities and the simultaneous fulfilling of work during quarantine. Under such circumstances, telework is employed as one of the important policies control the virus. Moreover, many employees have tendency for remote working or teleworking. In such a situation, the importance of applying the Bring Your Own Device (BYOD) approach to fulfill job duties seems obvious. To enjoy the benefits of BYOD, organizations need the right policy for applying BYOD. This perspective endeavors to shed light on how to apply BYOD policy. From the researchers’ point of view, the important facets that could be addressed when applying BYOD can be described like this: policy is appropriate decision-making and implementation, technical infrastructure, continuous communication, staff training, security and privacy protocols, and agreement between staff and organization as well as the use of cloud computing