SU(2) potentials in quantum gravity

We present investigations of the potential between static charges from a simulation of quantum gravity coupled to an SU(2) gauge field on $6^{3}\times 4$ and $8^{3}\times 4$ simplicial lattices. In the well-defined phase of the gravity sector where geometrical expectation values are stable, we study the correlations of Polyakov loops and extract the corresponding potentials between a source and sink separated by a distance $R$. In the confined phase, the potential has a linear form while in the deconfined phase, a screened Coulombic behavior is found. Our results indicate that quantum gravitational effects do not destroy confinement due to non-abelian gauge fields.Comment: 3 pages, contribution to Lattice 94 conference, uuencoded compressed postscript fil

Multicanonical Simulations Step by Step

The purpose of this article is to provide a starter kit for multicanonical simulations in statistical physics. Fortran code for the $q$-state Potts model in $d=2, 3,...$ dimensions can be downloaded from the Web and this paper describes simulation results, which are in all details reproducible by running prepared programs. To allow for comparison with exact results, the internal energy, the specific heat, the free energy and the entropy are calculated for the $d=2$ Ising ($q=2$) and the $q=10$ Potts model. % in a temperature range from $T=\infty$ down to sufficiently low % temperatures, such that the groundstates are included in the sampling. Analysis programs, relying on an all-log jackknife technique, which is suitable for handling sums of very large numbers, are introduced to calculate our final estimators

Totalitarianism and geography: L.S. Berg and the defence of an academic discipline in the age of Stalin

In considering the complex relationship between science and politics, the article focuses upon the career of the eminent Russian scholar, Lev Semenovich Berg (1876–1950), one of the leading geographers of the Stalin period. Already before the Russian Revolution, Berg had developed a naturalistic notion of landscape geography which later appeared to contradict some aspects of Marxist–Leninist ideology. Based partly upon Berg's personal archive, the article discusses the effects of the 1917 revolution, the radical changes which Stalin's cultural revolution (from the late 1920s) brought upon Soviet science, and the attacks made upon Berg and his concept of landscape geography thereafter. The ways in which Berg managed to defend his notion of geography (sometimes in surprisingly bold ways) are considered. It is argued that geography's position under Stalin was different from that of certain other disciplines in that its ideological disputes may have been regarded as of little significance by the party leaders, certainly by comparison with its practical importance, thus providing a degree of ‘freedom’ for some geographers at least analogous to that which has been described by Weiner (1999. A little corner of freedom: Russian nature protection from Stalin to Gorbachev. Berkeley: University of California Press) for conservationists. It is concluded that Berg and others successfully upheld a concept of scientific integrity and limited autonomy even under Stalinism, and that, in an era of ‘Big Science’, no modernizing state could or can afford to emasculate these things entirely

Normalized entropy density of the 3D 3-state Potts model

Using a multicanonical Metropolis algorithm we have performed Monte Carlo simulations of the 3D 3-state Potts model on $L^3$ lattices with L=20, 30, 40, 50. Covering a range of inverse temperatures from $\beta_{\min}=0$ to $\beta_{\max}=0.33$ we calculated the infinite volume limit of the entropy density $s(\beta)$ with its normalization obtained from $s(0)=\ln 3$. At the transition temperature the entropy and energy endpoints in the ordered and disordered phase are estimated employing a novel reweighting procedure. We also evaluate the transition temperature and the order-disorder interface tension. The latter estimate increases when capillary waves are taken into account.Comment: 5 pages, 4 figure

Perceived Quality in Surround Sound Systems

OPAQU

Lagrangian one-particle velocity statistics in a turbulent flow

We present Lagrangian one-particle statistics from the Risoe PTV experiment of a turbulent flow. We estimate the Lagrangian Kolmogorov constant $C_0$ and find that it is affected by the large scale inhomogeneities of the flow. The pdf of temporal velocity increments are highly non-Gaussian for small times which we interpret as a consequence of intermittency. Using Extended Self-Similarity we manage to quantify the intermittency and find that the deviations from Kolmogorov 1941 similarity scaling is larger in the Lagrangian framework than in the Eulerian. Through the multifractal model we calculate the multifractal dimension spectrum.Comment: 22 pages, 14 figure

Ideal Theory and "Ought Implies Can"

When we can’t live up to the ultimate standards of morality, how can moral theory give us guidance? We can distinguish between ideal and non-ideal theory to see that there are different versions of the voluntarist constraint, ‘ought implies can.’ Ideal moral theory identifies the best standard, so its demands are constrained by one version. Non-ideal theory tells us what to do given our psychological and motivational shortcomings and so is constrained by others. Moral theory can now both provide an ultimate standard and give us guidance; this view also gives us new insights into demandingness and blame

Down-to-earth economy: the discursive contribution of sustainable consumption and production debate

Sustainable consumption and production (SCP) is a topical concept as national SCP programmes have been drafted by several countries around Europe. This discourse analysis, based on interviews with Finnish SCP committee members, suggests that sustainable consumption and production can be a useful concept for approaching economy in a down-to-earth manner. It can enrich the environmental policy agenda that has long been dominated by technology-oriented ecological modernization. A critical point is, however, that the SCP depate is more concentrated on the needs of consumers than on the needs of poor, the initial focus of sustainable development. Moreover,ideas on how to really change consumption patterns seem to be scarce, scattered, and also contradictory among the SCP stakeholders

Fibonacci numbers and orthogonal polynomials

We prove that the sequence $(1/F_{n+2})_{n\ge 0}$ of reciprocals of the Fibonacci numbers is a moment sequence of a certain discrete probability, and we identify the orthogonal polynomials as little $q$-Jacobi polynomials with $q=(1-\sqrt{5})/(1+\sqrt{5})$. We prove that the corresponding kernel polynomials have integer coefficients, and from this we deduce that the inverse of the corresponding Hankel matrices $(1/F_{i+j+2})$ have integer entries. We prove analogous results for the Hilbert matrices.Comment: A note dated June 2007 has been added with some historical comments. Some references have been added and complete

On powers of Stieltjes moment sequences, II

We consider the set of Stieltjes moment sequences, for which every positive power is again a Stieltjes moment sequence, we and prove an integral representation of the logarithm of the moment sequence in analogy to the L\'evy-Khinchin representation. We use the result to construct product convolution semigroups with moments of all orders and to calculate their Mellin transforms. As an application we construct a positive generating function for the orthonormal Hermite polynomials.Comment: preprint, 21 page