Interplay of charge, spin, orbital and lattice correlations in colossal magnetoresistance manganites

We derive a realistic microscopic model for doped colossal magnetoresistance manganites, which includes the dynamics of charge, spin, orbital and lattice degrees of freedom on a quantum mechanical level. The model respects the SU(2) spin symmetry and the full multiplet structure of the manganese ions within the cubic lattice. Concentrating on the hole doped domain ($0\le x\le 0.5$) we study the influence of the electron-lattice interaction on spin and orbital correlations by means of exact diagonalisation techniques. We find that the lattice can cause a considerable suppression of the coupling between spin and orbital degrees of freedom and show how changes in the magnetic correlations are reflected in dynamic phonon correlations. In addition, our calculation gives detailed insights into orbital correlations and demonstrates the possibility of complex orbital states.Comment: 8 pages, 12 figures; more detailed versio

A new model to describe the physics of VOPO

In the past different models for the magnetic salt vanadyl pyrophosphate (VOPO) were discussed. Neither a spin ladder nor an alternating chain are capable to describe recently measured magnetic excitations. In this paper we propose a 2D model that fits better to experimental observations.Comment: 4 pages, 6 figures include

Records on the vanishing of Fourier coefficients of Powers Of the Dedekind Eta Function

In this paper we significantly extend Serre's table on the vanishing properties of Fourier coefficients of odd powers of the Dedekind eta function. We address several conjectures of Cohen and Str\"omberg and give a partial answer to a question of Ono. In the even-power case, we extend Lehmer's conjecture on the coefficients of the discriminant function $\Delta$ to all non-CM-forms. All our results are supported with numerical data. For example all Fourier coefficients $a_9(n)$ of the $9$-th power of the Dedekind eta function are non-vanishing for $n \leq 10^{10}$. We also relate the non-vanishing of the Fourier coefficients of $\Delta^2$ to Maeda's conjecture.Comment: 13 page

Corporate governance, competition, the new international financial architecture and large corporations in emerging markets

This paper examines from the developing countries perspective important analytical and policy issues arising from: a) the current international discussions about corporate governance in relation to the New International Financial Architecture; b) changes in the international competitive environment being caused by the enormous international merger movement in advanced countries. The paper's main conclusions include: the thesis that the deeper causes of the Asian crisis were the flawed systems of corporate governance and a poor competitive environment in the affected countries is not supported by the evidence; emerging markets, as well as European countries, have successful records of fast long-term growth with different governance systems, indeed superior to those of Anglo-Saxon countries; corporate financing patterns in emerging markets in the 1990s continue to be anomalous, as they were in the 1980s; and the claim that developing country conglomerates are inefficient and financially precarious is not supported by evidence or analysis.Corporate governance, competition, emerging markets.

Corporate Governance, Competetion, The new International Financial Architecture and Large Corporations in Emerging Markets

This paper examines from the developing countries perspective important analytical and policy issues arising from: a) the current international discussions about corporate governance in relation to the New International Financial Architecture; b) changes in the international competitive environment being caused by the enormous international merger movement in advanced countries. The background to a) above is the emergence of corporate governance as a key issue in the current G7 proposals for the New International Financial Architecture. The G7 emphasis on corporate governance can be traced back to the thesis that the ‘deeper’ reasons for the Asian crisis lay in the microeconomic behaviour of corporations and businesses in the affected countries. The failings of the corporate governance mechanisms and distortions in the competitive process have received special scrutiny in such analyses. With respect to b) above, the context is that the largest corporations in advanced countries are currently in the process of potentially cartelising the world market place through a spate of cross-border mergers and take-overs. This huge merger movement raises serious policy concerns for developing countries. The paper's main conclusions are: 1. The thesis that the deeper causes of the Asian crisis were the flawed systems of corporate governance and a poor competitive environment in the affected countries is not supported by evidence. 2. The Anglo-Saxon model of widely held corporations with dispersed share ownership is by far the exception in developing countries and in much of continental Europe. Empirical evidence suggests that emerging markets, as well as European countries such as Italy, Sweden or Germany have successful records of fast long-term growth with different governance systems, indeed superior to those of Anglo-Saxon countries. 3. Empirical evidence does not support the view that the Asian crisis 1997 to 1999 was caused by crony capitalism. 4. Corporate financing patterns in emerging markets in the 1990s were broadly similar to those observed in the 1980s. Unlike their counterparts in advanced countries, large developing countries firms continued to rely overwhelmingly on external sources to finance their growth of total assets. 5. The analysis of this paper does not support the claim that developing country conglomerates are inefficient, financially precarious and necessarily create moral hazard. It also indicates that contrary to widely held beliefs, product market competition in emerging countries is no less intense than in advanced economies. Acknowledgements Please do not quote without permission from the authors. Comments are most welcome.Competition; Corporate Governance; Emerging Markets

The Kernel Polynomial Method

Efficient and stable algorithms for the calculation of spectral quantities and correlation functions are some of the key tools in computational condensed matter physics. In this article we review basic properties and recent developments of Chebyshev expansion based algorithms and the Kernel Polynomial Method. Characterized by a resource consumption that scales linearly with the problem dimension these methods enjoyed growing popularity over the last decade and found broad application not only in physics. Representative examples from the fields of disordered systems, strongly correlated electrons, electron-phonon interaction, and quantum spin systems we discuss in detail. In addition, we illustrate how the Kernel Polynomial Method is successfully embedded into other numerical techniques, such as Cluster Perturbation Theory or Monte Carlo simulation.Comment: 32 pages, 17 figs; revised versio

Shareholder value maximisation, stock market and new technology: should the US corporate model be the universal standard

In 1992 a blue-ribbon group of US economists led by Michael Porter concluded that the US stock market-based corporate model was misallocating resources and jeopardising US competitiveness. The faster growth of US economy since then and the supposed US lead in the spread of information technology has brought new legitimacy to the stock market and the corporate model, which is being hailed as the universal standard. Two main conclusions of the analysis presented here are: (a) there is no warrant for revising the blue-ribbon groupÕs conclusion; and (b) even US corporations let alone developing country ones would be better off not having stock market valuation as a corporate goal.Shareholder wealth, Information technology, Stock-market efficiency

Early tumor response to intraarterial or intravenous administration of carboplatin to treat naturally occurring lower urinary tract carcinoma in dogs.

BackgroundSurvival times and tumor responses associated with malignant neoplasia of the lower urinary tract are poor despite the vast array of current treatments. Therefore, the evaluation of alternative treatments, such as intraarterial administration of chemotherapy (IAC) should be considered.ObjectiveTo describe a technique for superselective catheterization for IAC and to evaluate initial tumor response by ultrasonography after both IAC and intravenous administration of chemotherapy (IVC).AnimalsClient-owned dogs with lower urinary tract neoplasia treated with either IVC (n = 15) or IAC (n = 11).MethodsRetrospective study. An arterial approach via the carotid or femoral artery was utilized to obtain superselective access and administer chemotherapy in the IAC cases. Medical record review was performed, data were recorded, and recorded variables were evaluated statistically.ResultsIntraarterial chemotherapy was successfully administered in all cases. There was a significantly greater decrease in longest unidimensional measurement in the IAC group as compared to the IVC group (P = .013). The IAC group was also significantly more likely to have a tumor response as assessed by modified RECIST guidelines (P = .049). Dogs in the IAC group were significantly less likely to develop anemia (P = .001), lethargy (P = .010) and anorexia (P = .024).Conclusion and clinical importanceThis study demonstrated the feasibility and efficacy of performing IAC for lower urinary tract neoplasia. Further investigation is necessary as the follow-up time was short and the impact on long-term outcome and survival was not determined