New Group V Elemental Bilayers: A Tunable Structure Model with 4,6,8-atom Rings

Two-dimensional (2D) group V elemental materials have attracted widespread attention due to their nonzero band gap while displaying high electron mobility. Using first-principles calculations, we propose a series of new elemental bilayers with group V elements (Bi, Sb, As). Our study reveals the dynamical stability of 4, 6, and 8-atom ring structures, demonstrating their possible coexistence in such bilayer systems. The proposed structures for Sb and As are large-gap semiconductors that are potentially interesting for applications in future nanodevices. The Bi structures have nontrivial topological properties with a large and direct nontrivial band gap. The nontrivial gap is shown to arise from a band inversion at the Brillouin zone center due to the strong intrinsic spin-orbit coupling (SOC) in Bi atoms. Moreover, we demonstrate the possibility to tune the properties of these materials by enhancing the ratio of 6-atom rings to 4 and 8-atom rings, which results in wider nontrivial band gaps and lower formation energies

The magnetic, electronic, and light-induced topological properties in two-dimensional hexagonal FeX2 (X = Cl, Br, I) monolayers

Topological materials are fertile ground for investigating topological phases of matter and topological phase transitions. In particular, the quest for novel topological phases in 2D materials is attracting fast growing attention. Here, using Floquet-Bloch theory, we propose to realize chiral topological phases in 2D hexagonal FeX2 (X=Cl, Br, I) monolayers under irradiation of circularly polarized light. Such 2D FeX2 monolayers are predicted to be dynamical stable, and exhibit both ferromagnetic and semiconducting properties. To capture the full topological physics of the magnetic semiconductor under periodic driving, we adopt ab initio Wannier-based tight-binding methods for the Floquet-Bloch bands, with the light-induced band gap closings and openings being obtained as the light field strength increases. The calculations of slab with open boundaries show the existence of chiral edge states. Interestingly, the topological transitions with branches of chiral edge states changing from zero to one and from one to two by tuning the light amplitude are obtained, showing that the topological floquet phase of high Chern number can be induced in the present Floquet-Bloch systems

Quantum anomalous Hall effect in stable 1T-YN2_2 monolayer with a large nontrivial band gap and high Chern number

The quantum anomalous Hall (QAH) effect is a topologically nontrivial phase, characterized by a non-zero Chern number defined in the bulk and chiral edge states in the boundary. Using first-principles calculations, we demonstrate the presence of the QAH effect in 1T-YN$_2$ monolayer, which was recently predicted to be a Dirac half metal without spin-orbit coupling (SOC). We show that the inclusion of SOC opens up a large nontrivial band gap of nearly $0.1$ eV in the electronic band structure. This results in the nontrivial bulk topology which is confirmed by the calculation of Berry curvature, anomalous Hall conductance and the presence of chiral edge states. Remarkably, a high Chern number $C = 3$ is found, and there are three corresponding gapless chiral edge states emerging inside the bulk gap. Our results open a new avenue in searching for QAH insulators with high temperature and high Chern numbers, which can have nontrivial practical applications

Financial Inclusion: progress, motivations and impact

Financiële inclusie wordt globaal bevorderd door overheden en internationale organisaties als een krachtig instrument om extreme armoede te elimineren en de economische vooruitgang te versnellen. Toch blijven er een aantal vragen over financiele integratie. Bijvoorbeeld, welke vooruitgang is er geboekt in de wereldwijde bevordering van financiële integratie in de afgelopen jaren? Wat stimuleert huishoudens om op de financiële markt te stappen, en wat stimuleert banken om financiële diensten aan de armen te bieden? Wat is de impact van financiële inclusie op het leven van de armen? Met behulp van twee bronnen van gegevens over globale microfinancieringsinstellingen, dat wil zeggen de aanbodzijde van de financiële markt en gegevens over huishoudens in China, dat wil zeggen de vraagzijde van de financiële markt, beantwoordt deze proefschrift bovenstaande vragen en schetst de vooruitgang, de motivaties en de impact van de financiële inclusie.Financial inclusion is promoted globally by governments and international organizations as a powerful tool for eliminating extreme poverty and accelerating economic progress. Yet, a number of questions about financial inclusion remain. For instance, what progress has been made in the worldwide promotion of financial inclusion in recent years? What motivates households to step in the financial market, and what motivates banks to provide financial services to the poor? What is the impact of financial inclusion on the lives of the poor? Using two sources of data covering global microfinance institutions, i.e. the supply side of financial market, and data covering households in China, i.e. the demand side of financial market, this thesis answers above questions and shed light on the progress, motivations and impact of financial inclusion

Scoping Review On Gonorrhea Vaccines

Gonorrhea infection is caused by Neisseria gonorrhoeae and it is the second most common bacterial sexually transmitted infection around the globe. Although gonorrhea infection is treatable with antibiotics, the level of antimicrobial resistance continues to increase and has become a major public health concern. As options of available treatments are reduced by the emergence of AMR, it has become urgent to develop effective vaccines against gonorrhea infection. The purpose of this scoping review is to describe existing epidemiological evidence in support of gonorrhea vaccine development, to discuss the current vaccine candidates in clinical stages, and to evaluate the theoretical impact of gonorrhea vaccines. Published papers and clinical trial records on gonorrhea vaccine immunogenicity and efficacy, vaccine effectiveness and potential impact were reviewed after selection. Outer membrane vesicles-based meningococcal serogroup B vaccination showed moderate (approximate 30%) cross-protection against gonorrhea infections in multiple retrospective studies, and subsequent clinical studies assessing the immunogenicity and vaccine efficacy are currently undergoing. Modeling studies suggested that the theoretical impact of gonorrhea vaccines vary by vaccine efficacy, mode of action, duration of protection, uptake percentage, and disease prevalence in the population, but a vaccine with efficacy and duration of protection equivalent to the meningococcal serogroup B vaccine can have substantial impact and public health value if delivered in optimal vaccination strategy. However, generalizability of the study results remains questionable because studies included were mostly limited to developed country settings. To investigate vaccines with higher efficacy and to better evaluate the value of potential gonorrhea vaccines, research on disease natural history and gonorrhea epidemiology in low- or middle-income countries in the near future

Joint Motion Deblurring and Superresolution from Single Blurry Image

Currently superresolution from a motion blurred image still remains a challenging task. The conventional approach, which preprocesses the blurry low resolution (LR) image with a deblurring algorithm and employs a superresolution algorithm, has the following limitation. The high frequency texture of the image is unavoidably lost in the deblurring process and this loss restricts the performance of the subsequent superresolution process. This paper presents a novel technique that performs motion deblurring and superresolution jointly from one single blurry image. The basic idea is to regularize the ill-posed reconstruction problem using an edge-preserving gradient prior and a sparse kernel prior. This method derives from an inverse problem approach under an efficient optimization scheme that alternates between blur kernel estimation and superresolving until convergence. Furthermore, this paper proposes a simple and efficient refinement formulation to remove artifacts and render better deblurred high resolution (HR) images. The improvements brought by the proposed combined framework are demonstrated by the processing results of both simulated and real-life images. Quantitative and qualitative results on challenging examples show that the proposed method outperforms the existing state-of-the-art methods and effectively eliminates motion blur and artifacts in the superresolved image