Superfluidity and Superconductivity in Body-centred-cubic and Face-centred-cubic Systems

The microscopic description of phases in strongly correlated systems such as the fullerides (A3C60) is a challenge. In particular, how these strong interactions become attraction leading to a superconducting state remains a mystery. Understanding the mechanism(s) that drive(s) unconventional superconductivity is one of the most sought-after goals in many-body physics and indeed very complex to solve. The aim of this thesis is, firstly, to investigate the conditions in which pairing may take place between two electrons in both body-centred cubic (BCC) and face-centred cubic (FCC) systems, and secondly, to examine the possibility for the emergence of a superconducting or superfluid state from paired electrons in three-dimensional (3D) systems. Here, pair properties are studied both in the anti-adiabatic and adiabatic limits. In the anti-adiabatic limit, we use a symmetrised approach, group theory analysis, and perturbation theory to exactly solve the two-body problem and analyse the properties of the electron pair. We also examine, using a continuous-time Monte Carlo algorithm (CTQMC), the effects of retarded electron-phonon interactions on the pair properties away from the anti-adiabatic limit. In the high-phonon frequency limit, the CTQMC also serves as a validation check for the anti-adiabatic analytic result and vice-versa (with both results showing perfect agreement). Our result predicts that superfluidity can occur in BCC optical lattices up to a few tens of nanokelvin for fermionic lithium-6 atoms. Additionally, we found that, in the high-frequency limit, a paired state in an FCC lattice can be extremely light and small as compared to paired states on other 3D lattices. Such superlight states are expected to yield high transition temperatures under favourable circumstances. However, when the retardation effects arising from the electron-phonon interaction become important, bound pairs in the BCC lattice become lighter by orders of magnitude in a wide region of the parameter space. We also found significant long-range effects due to the vibration of the alkali ions in the cesium-doped fulleride systems leading to the creation of light pairs in its BCC structure

E-business capabilities in developed and developing countries: Different or the same?

This paper compares the e-business capabilities in developed and developing countries; in particular the awareness and usage of e-business tools and the barriers / drivers of adoption. We surveyed 136 managers of organizations (in both developed and developing countries) and analyzed the responses via the SPSS Statistics software package. A number of statistically significant differences were found between the 2 sets of organization; interestingly, however, a number of areas showed minimal difference between the 2 sets of organizations, suggesting the gap between them beginning to close

Key enablers and barriers of solar paver technologies for the advancement of environmental sustainability

Global initiatives to improve environmental sustainability have centered on reducing energy consumption and developing technological solutions for greener power generation. Current insights on innovations for environmental sustainability are primarily from developed countries, with limited studies originating from developing countries. This study focuses on solar paver technology, a potential innovation for sustainable generation of power. The interest in this technology lies in its dual-purpose ability to enable both functional road surfaces and the use of solar roadways that can generate electricity to power other road infrastructure such as electric lights. To maximize the potential of success of deployment of solar pavers, it is important to investigate the practicalities of solar pavers and understand the perceptions of stakeholders that will be responsible for the implementation of solar pavers. This research addresses this gap in knowledge. Thirty construction industry stakeholders in Malaysia were interviewed through focus group discussions and interviews. This study applied the diffusion of innovation theory to develop an understanding of the nuances of solar pavers. The findings identified three superordinate categories (motivation, opportunity, and ability) and nine categories (compliance with green initiatives, promote corporate social responsibility, dual functionality, financial incentives, sunny climate, increased environmental awareness, green experience, experts network and familiarity with solar technology) as the key enablers. Key barriers constitute two superordinate categories (challenges and weaknesses) and ten categories (reluctant authority, vandalism, complexity of installation and maintenance, high humidity and rainfall, negative environmental impact, high cost, design flaws, low efficiency, questionable practicality, and better comparative opportunities). There is an acceptance of solar pavers by the stakeholders and cost and ownership structures are the key to the deployment. The findings provide fresh insights into a new form of sustainable solar paver engendering new streams of research in construction engineering and technology management. Implications for management and organizational research are discussed

Supplier selection activities in the service sector: A case study in Nigeria

This paper presents the results of the supplier selection process conducted by a Nigerian service sector organization. One organization was used as a case study whereby data collection involved an action research approach; the data was then subject to statistical analysis via the SPSS Statistics software package. In total, 185 potential suppliers were assessed. Several statistically significant differences were also found between those suppliers that met the minimum requirements and those that did not as well as between organizations that offered products and organizations that offered services

Usefulness of Chlamydia serology in prediction of tubal factor infertility among infertile patients at Federal Medical Centre, Bida, North Central Nigeria

Background: Infertility is a major public health problem in developing countries where pelvic inflammatory disease due mainly to Chlamydia trachomatis and Neisseria gonorrhea infection have been implicated. The role of Chlamydia serology in predicting tubal factor infertility (TFI) has been demonstrated by many researchers elsewhere. However, there are limited data in our environment. This prospective cross-sectional study aims to determine the usefulness of Chlamydia Serology as a screening tool for TFI at Federal Medical Centre, Bida, North Central Nigeria.Methods: 125 women with infertility who met the inclusion criteria were enrolled into the study. Relevant information on their socio-demographic characteristics, gynaecological symptoms and risks factors for infertility were obtained. Participants had Hysterosalpingography (HSG) as part of their fertility work-up while 5ml of venous blood was withdrawn to check for Immunoglobulin G antibody to Chlamydia trachomatis using rapid test kits. The HSG findings were correlated with the result of Chlamydia serology. Data was analyzed using the computer software, Statistical Package for Social Science (SPSS) version 20. The level of significance (p value) was set at 0.05.Results: A total of 120 infertile women completed the study, 5 had incomplete investigations and were excluded from the analysis. The prevalence of TFI was 47.5%, while that of positive chlamydia serology was 36.5%. The prevalence of chlamydial seropositivity was 59.6% for patients with TFI but 15.9% for non-TFI. There was a significant association between positive chlamydia serology and TFI p< 0.05. The study revealed moderate sensitivity 59.6%, and negative predictive value 69.7% but high specificity 84.1% and positive predictive value of 77.2%. In this study the odds for diagnosing tubal infertility was 7.8.Conclusions: Chlamydia serology is useful in predicting TFI and should be incorporated in the routine work up for infertility

Ubiquitous light real-space pairing from long-range hopping and interactions

We systematically examine how long-range hopping and its synergy with extended interactions leads to light bound pairs. Pair properties are determined for a dilute extended Hubbard model with large on-site repulsion (U) and both near- and next-nearest neighbor hopping (t and t' ) and attraction (V and V'), for cubic and tetragonal lattices. The presence of t' and V' promotes light pairs. For tetragonal lattices, t' d-symmetric pairs form. Close packing transition temperatures, T*, are estimated for the Bose-Einstein condensation (BEC) of pairs to be kBT* ~ 0.1̄t , where ̄t is the geometric mean of the hoppings on the Cartesian axes. When pairs have d-symmetry, the condensate has d-wave character. Thus, the presence of both t' and V' leads ubiquitously to small strongly bound pairs with an inverse mass that is linear in hopping, which could lead to high temperature BECs

A study of the activities and impact of the Asian productivity organisation (APO)

Purpose: The purpose of this study is to investigate the activities of the Asian Productivity Organisation (APO). The study identifies the various roles and activities of the APO and evaluates how well it performs in these roles. The study also investigates the impacts of the APO on the productivity initiatives of National Productivity Organisations (NPOs) in sixteen Asian countries. These productivity initiatives are important in enhancing productivity performance and national competitiveness in the countries of interest. Design/methodology/approach: The study collects data from stakeholders in the NPOs in sixteen countries. A likert-scale questionnaire was used to collect data from two types of respondents – NPO CEOs and NPO professional/technical staff. Data was analysed by comparing the responses across the participating countries. Findings: The result shows that there was general satisfaction with the mission, vision, and strategic direction of the APO. With respect to the operational performance of the organisation, the study showed that there were some differences in perception of the performance of the APO although the overall perception was positive. Practical Implications: The study provides insights to the top management of the APO with regards to deciding on the future direction of the organisation and, in particular, the ways in which it understands and supports the varied requirements of the different NPOs. Originality/value: Organisations such as the APO dedicate significant resources into supporting NPOs, and by extension productivity-related commercial operations, in several countries. It is important to understand how these services are perceived and experienced in these countries and a definitive study to examine this has not previously been carried out

Superlight pairs in face-centred-cubic extended Hubbard models with strong Coulomb repulsion

The majority of fulleride superconductors with unusually high transition-temperature to kinetic-energy ratios have a face-centred-cubic (FCC) structure. We demonstrate that, within extended Hubbard models with strong Coulomb repulsion, paired fermions in FCC lattices have qualitatively different properties than pairs in other three-dimensional cubic lattices. Our results show that strongly bound, light, and small pairs can be generated in FCC lattices across a wide range of the parameter space. We estimate that such pairs can Bose condense at high temperatures even if the lattice constant is large (as in the fullerides)

Neuropathology and Inflammatory Cell Characterization in 10 Autoptic COVID-19 Brains

COVID-19 presents with a wide range of clinical neurological manifestations. It has been recognized that SARS-CoV-2 infection affects both the central and peripheral nervous system, leading to smell and taste disturbances; acute ischemic and hemorrhagic cerebrovascular disease; encephalopathies and seizures; and causes most surviving patients to have long lasting neurological symptoms. Despite this, typical neuropathological features associated with the infection have still not been identified. Studies of post-mortem examinations of the cerebral cortex are obtained with difficulty due to laboratory safety concerns. In addition, they represent cases with different neurological symptoms, age or comorbidities, thus a larger number of brain autoptic data from multiple institutions would be crucial. Histopathological findings described here are aimed to increase the current knowledge on neuropathology of COVID-19 patients. We report post-mortem neuropathological findings of ten COVID-19 patients. A wide range of neuropathological lesions were seen. The cerebral cortex of all patients showed vascular changes, hyperemia of the meninges and perivascular inflammation in the cerebral parenchyma with hypoxic neuronal injury. Perivascular lymphocytic inflammation of predominantly CD8-positive T cells mixed with CD68-positive macrophages, targeting the disrupted vascular wall in the cerebral cortex, cerebellum and pons were seen. Our findings support recent reports highlighting a role of microvascular injury in COVID-19 neurological manifestations