Two-dimensional Anderson-Hubbard model in DMFT+Sigma approximation

Density of states, dynamic (optical) conductivity and phase diagram of paramagnetic two-dimensional Anderson-Hubbard model with strong correlations and disorder are analyzed within the generalized dynamical mean-field theory (DMFT+Sigma approximation). Strong correlations are accounted by DMFT, while disorder is taken into account via the appropriate generalization of the self-consistent theory of localization. We consider the two-dimensional system with the rectangular "bare" density of states (DOS). The DMFT effective single impurity problem is solved by numerical renormalization group (NRG). Phases of "correlated metal", Mott insulator and correlated Anderson insulator are identified from the evolution of density of states, optical conductivity and localization length, demonstrating both Mott-Hubbard and Anderson metal-insulator transitions in two-dimensional systems of the finite size, allowing us to construct the complete zero-temperature phase diagram of paramagnetic Anderson-Hubbard model. Localization length in our approximation is practically independent of the strength of Hubbard correlations. However, the divergence of localization length in finite size two-dimensional system at small disorder signifies the existence of an effective Anderson transition.Comment: 10 pages, 10 figures, improve phase diagra

Small Disks and Semiclassical Resonances

We study the effect on quantum spectra of the existence of small circular disks in a billiard system. In the limit where the disk radii vanish there is no effect, however this limit is approached very slowly so that even very small radii have comparatively large effects. We include diffractive orbits which scatter off the small disks in the periodic orbit expansion. This situation is formally similar to edge diffraction except that the disk radii introduce a length scale in the problem such that for wave lengths smaller than the order of the disk radius we recover the usual semi-classical approximation; however, for wave lengths larger than the order of the disk radius there is a qualitatively different behaviour. We test the theory by successfully estimating the positions of scattering resonances in geometries consisting of three and four small disks.Comment: Final published version - some changes in the discussion and the labels on one figure are correcte

A systematic experimental neuropsychological investigation of the functional integrity of working memory circuits in major depression

Verbal and visuospatial working memory (WM) impairment is a well-documented finding in psychiatric patients suffering from major psychoses such as schizophrenia or bipolar affective disorder. However, in major depression (MDD) the literature on the presence and the extent of WM deficits is inconsistent. The use of a multitude of different WM tasks most of which lack process-specificity may have contributed to these inconsistencies. Eighteen MDD patients and 18 healthy controls matched with regard to age, gender and education were tested using process- and circuit-specific WM tasks for which clear brain-behaviour relationships had been established in prior functional neuroimaging studies. Patients suffering from acute MDD showed a selective impairment in articulatory rehearsal of verbal information in working memory. By contrast, visuospatial WM was unimpaired in this sample. There were no significant correlations between symptom severity and WM performance. These data indicate a dysfunction of a specific verbal WM system in acutely ill patients with MDD. As the observed functional deficit did not correlate with different symptom scores, further, longitudinal studies are required to clarify whether and how this deficit is related to illness acuity and clinical state of MDD patients

Alleviating poverty through Islamic microfinance: factors and measures of financial performance, and roles of Islamic values and financial policies

Indonesia has a strong presence of microfinance sector with the number of Islamic Microfinance Institutions (IMFIs) estimated to be around 5,000 currently. Microfinance is an effective tool in alleviating poverty in Indonesia due to the limited access to financial services by the poor who accounted for approximately 96 million Indonesians (or 37% of the total population), living on less than USD 1.90 a day. In the absence of collateral and steady income, the poor are considered too risky to be given credit facilities by the formal financial services providers and living in remote areas has also limited their access to formal financial services. This study aims to examine the poverty alleviation efforts from the perspective of the IMFIs in view of their direct involvement in the process and having rich information about financial issues facing the borrowers. The managers also understand about financial inclusion agenda as well as financial guidelines and regulations issued by the relevant authorities. A total of 34 managers of Baitulmaal Wa Tamwil (BMTs), which registered under the Sharia Cooperative Centre (INKOPSYAH) are taken as respondents from the Jakarta, Bogor, Depok, Tangerang and Bekasi (JABODETABEK) areas. The first instrument was a survey questionnaire, and the second one was an in-depth interview to outline data related to the model design. The findings of this research are expected to contribute to better decision-making for the BMTs to further enhance its role in alleviating poverty. The findings also elaborate several dimensions to improving financial inclusion among the poor including providing financial services, implementing Islamic principles, significant policies, community-based framework concept and training financial education. This research highlights the need for a variety of strategies to warrant success of poverty alleviation efforts by BMT

Geometry and material effects in Casimir physics - Scattering theory

We give a comprehensive presentation of methods for calculating the Casimir force to arbitrary accuracy, for any number of objects, arbitrary shapes, susceptibility functions, and separations. The technique is applicable to objects immersed in media other than vacuum, to nonzero temperatures, and to spatial arrangements in which one object is enclosed in another. Our method combines each object's classical electromagnetic scattering amplitude with universal translation matrices, which convert between the bases used to calculate scattering for each object, but are otherwise independent of the details of the individual objects. This approach, which combines methods of statistical physics and scattering theory, is well suited to analyze many diverse phenomena. We illustrate its power and versatility by a number of examples, which show how the interplay of geometry and material properties helps to understand and control Casimir forces. We also examine whether electrodynamic Casimir forces can lead to stable levitation. Neglecting permeabilities, we prove that any equilibrium position of objects subject to such forces is unstable if the permittivities of all objects are higher or lower than that of the enveloping medium; the former being the generic case for ordinary materials in vacuum.Comment: 44 pages, 11 figures, to appear in upcoming Lecture Notes in Physics volume in Casimir physic

Investigating the uses of corporate reputation and its effects on brand segmentation, brand differentiation and brand positioning: evidence from the Taiwanese pharmaceutical industry

This study advances current knowledge on building a brand strategy that includes corporate reputation. It employs three theories – value creation, strategic resources and corporate communication – to study the uses of corporate reputation and its effect on brand segmentation, brand differentiation and brand positioning. In the context of the Taiwanese pharmaceutical industry, a sequential mixed method approach is applied and data are analyzed using PLS SEM. Findings demonstrate the relative impacts of three uses of corporate reputation (value creation, strategic resources and corporate communication) on brand image strategy (brand segmentation, brand differentiation and brand positioning) and the implications are evaluated. This study discovers that the inclusion of medicine prices is necessary and that it negatively moderates the impact of the overall uses of corporate reputation on overall brand image strategy. This research contributes empirically as one of the few that tests reputation-and-branding-building models outside the USA and Europe