Normal state diamagnetism of charged bosons in cuprate superconductors

Normal state orbital diamagnetism of charged bosons quantitatively accounts for recent high-resolution magnetometery results near and above the resistive critical temperature Tc of superconducting cuprates. Our parameter-free descriptions of normal state diamagnetism, Tc, upper critical fields and specific heat anomalies unambiguously support the 3D Bose-Einstein condensation at Tc of preformed real-space pairs with zero off-diagonal order parameter above Tc, at variance with phase fluctuation (or vortex) scenarios of the "normal" state of cuprates.Comment: 10 pages, 4 figure

Petroleum Profit Tax and Nigeria Economic Development

Petroleum Profit Tax is a major source of revenue for the Federal Government of Nigeria to meet its statutory obligations of ensuring the economic development of Nigeria. It assists the government to achieve the country’s macroeconomic objective in the areas of fiscal and monetary policies.However,it has been observed that non-provision of corporate social responsibilities in the communities where there is extraction of crude oil result into constant destruction of production installations, and hindrance to production; tax avoidance and evasion d poor tax administration, and weak fiscal policy have been negating the increase in tax income generated. The main objective of this paper is to assess the relationship between petroleum profit tax and economic development of Nigeria for the enhancement of the welfare of the citizens. Primary and secondary data were used to collect the research data, while chi-square and multiple regression statistical models were used to analyze the results of the field work. The findings reveal that there is a very strong relationship between petroleum profit tax and economic development of Nigeria, tax avoidance and evasion are major hindrance to income growth in this sector, poor tax administration is a problem to effectiveness and efficiency of this source of income, and lack of corporate social responsibilities is causing unrest in the crude oil production zone. The paper recommends the need for the government to make judicious use income generated for the benefits of Nigerians, and among others the need for tax reforms to address the issue of tax evasion and avoidance

Globalization and the Precarious State of Public Finance in Nigeria

As globalization eviscerates national borders, governments in both developed and developing countries are discovering that their tax base is eroding, especially their ability to tax the proceeds and profits from corporate investment and finance Domestic revenue mobilization is key to sustainable development finance – only selfsufficiency will allow the development of fully-functioning states with flourishing systems of political representation and economies reflecting societies’ expressed preferences in regard to, for example, inequality. The significant of this paper therefore is that it will enable the revenue authority take necessary steps to prevent tax avoidance and tax evasion so as to increase the level of domestic revenue for development. It concluded that claims of corporate social responsibility are undermined when low corporate tax payments are exposed and a process of tax competition at the global level undermines the social contract previously set within the national arena, as states compete to offer tax exemption to capital. The paper suggested that with effective tax administration, adequate taxation of transnational corporations, tax compliance as part of corporate accountability, international tax cooperation, fight against bribery and corruption, arm length international trade negotiations and reduction in military expenditure, the problems are more likely to be solved

Newtonian Perturbations on Models with Matter Creation

Creation of Cold Dark Matter (CCDM) can macroscopically be described by a negative pressure, and, therefore, the mechanism is capable to accelerate the Universe, without the need of an additional dark energy component. In this framework we discuss the evolution of perturbations by considering a Neo-Newtonian approach where, unlike in the standard Newtonian cosmology, the fluid pressure is taken into account even in the homogeneous and isotropic background equations (Lima, Zanchin and Brandenberger, MNRAS {\bf 291}, L1, 1997). The evolution of the density contrast is calculated in the linear approximation and compared to the one predicted by the $\Lambda$CDM model. The difference between the CCDM and $\Lambda$CDM predictions at the perturbative level is quantified by using three different statistical methods, namely: a simple $\chi^{2}$-analysis in the relevant space parameter, a Bayesian statistical inference, and, finally, a Kolmogorov-Smirnov test. We find that under certain circumstances the CCDM scenario analysed here predicts an overall dynamics (including Hubble flow and matter fluctuation field) which fully recovers that of the traditional cosmic concordance model. Our basic conclusion is that such a reduction of the dark sector provides a viable alternative description to the accelerating $\Lambda$CDM cosmology.Comment: Physical Review D in press, 10 pages, 4 figure

Estimative for the size of the compactification radius of a one extra dimension Universe

In this work, we use the Casimir effect to probe the existence of one extra dimension. We begin by evaluating the Casimir pressure between two plates in a $M^4\times S^1$ manifold, and then use an appropriate statistical analysis in order to compare the theoretical expression with a recent experimental data and set bounds for the compactification radius

A note on the invariant distribution of a quasi-birth-and-death process

The aim of this paper is to give an explicit formula of the invariant distribution of a quasi-birth-and-death process in terms of the block entries of the transition probability matrix using a matrix-valued orthogonal polynomials approach. We will show that the invariant distribution can be computed using the squared norms of the corresponding matrix-valued orthogonal polynomials, no matter if they are or not diagonal matrices. We will give an example where the squared norms are not diagonal matrices, but nevertheless we can compute its invariant distribution