Topological structures in the equities market network

We present a new method for articulating scale-dependent topological descriptions of the network structure inherent in many complex systems. The technique is based on "Partition Decoupled Null Models,'' a new class of null models that incorporate the interaction of clustered partitions into a random model and generalize the Gaussian ensemble. As an application we analyze a correlation matrix derived from four years of close prices of equities in the NYSE and NASDAQ. In this example we expose (1) a natural structure composed of two interacting partitions of the market that both agrees with and generalizes standard notions of scale (eg., sector and industry) and (2) structure in the first partition that is a topological manifestation of a well-known pattern of capital flow called "sector rotation.'' Our approach gives rise to a natural form of multiresolution analysis of the underlying time series that naturally decomposes the basic data in terms of the effects of the different scales at which it clusters. The equities market is a prototypical complex system and we expect that our approach will be of use in understanding a broad class of complex systems in which correlation structures are resident.Comment: 17 pages, 4 figures, 3 table

A crossing probability for critical percolation in two dimensions

Langlands et al. considered two crossing probabilities, pi_h and pi_{hv}, in their extensive numerical investigations of critical percolation in two dimensions. Cardy was able to find the exact form of pi_h by treating it as a correlation function of boundary operators in the Q goes to 1 limit of the Q state Potts model. We extend his results to find an analogous formula for pi_{hv} which compares very well with the numerical results.Comment: 8 pages, Latex2e, 1 figure, uuencoded compressed tar file, (1 typo changed

Paradoxical popups: Why are they hard to catch?

Even professional baseball players occasionally find it difficult to gracefully approach seemingly routine pop-ups. This paper describes a set of towering pop-ups with trajectories that exhibit cusps and loops near the apex. For a normal fly ball, the horizontal velocity is continuously decreasing due to drag caused by air resistance. But for pop-ups, the Magnus force (the force due to the ball spinning in a moving airflow) is larger than the drag force. In these cases the horizontal velocity decreases in the beginning, like a normal fly ball, but after the apex, the Magnus force accelerates the horizontal motion. We refer to this class of pop-ups as paradoxical because they appear to misinform the typically robust optical control strategies used by fielders and lead to systematic vacillation in running paths, especially when a trajectory terminates near the fielder. In short, some of the dancing around when infielders pursue pop-ups can be well explained as a combination of bizarre trajectories and misguidance by the normally reliable optical control strategy, rather than apparent fielder error. Former major league infielders confirm that our model agrees with their experiences.Comment: 28 pages, 10 figures, sumitted to American Journal of Physic

Finite size effects in perturbed boundary conformal field theories

We discuss the finite-size properties of a simple integrable quantum field theory in 1+1 dimensions with non-trivial boundary conditions. Novel off-critical identities between cylinder partition functions of models with differing boundary conditions are derived.Comment: 7 pages, 11 figures, JHEP proceedings style. Uses epsfig, amssymb. Talk given at the conference `Nonperturbative Quantum Effects 2000', Pari

The Effect of Operational and Strategic Planning on Small Firm Performance

Unlike large corporations, small businesses face a multiplicity of problems that could spell immediate doomfor the organization. As a result,an increasing body of research add ressing small business problems has been noted in the literature. This research stud y investigated  the effect of opera Honal and st rategic:-ilanning on small firm performance and found  that both were positivel y related to performance.  Practical implications of  these research findings  are provided  for  small businesses

Vibration and loads in hingeless rotors. Volume 2: Experimental data

Descriptions, geometry, and technical data covering three rotor systems are presented. Tables of experimental data gathered during wind tunnel testing of two of the systems are included. Both analyzed experimental data, ready for comparison with theory, and the basic reduced data from which they were obtained are reported

Mean-field theory for clustering coefficients in Barabasi-Albert networks

We applied a mean field approach to study clustering coefficients in Barabasi-Albert networks. We found that the local clustering in BA networks depends on the node degree. Analytic results have been compared to extensive numerical simulations finding a very good agreement for nodes with low degrees. Clustering coefficient of a whole network calculated from our approach perfectly fits numerical data.Comment: 8 pages, 3 figure

Gravity anomalies and flexure of the lithosphere: A three-dimensional study of the Great Meteor Seamount, northeast Atlantic

Simple models for the flexure of the lithosphere caused by the load of the Great Meteor seamount have been determined for different assumed values of the effective flexural rigidity of the lithosphere. The models utilize a new method for determining the flexure of the lithosphere caused by a three-dimensional load. The gravity effect of the models has been computed and compared with observed free-air anomalies in the vicinity of the seamount. Computations show that the observed free-air anomalies can be most satisfactorily explained for an assumed effective flexural rigidity of the lithosphere of about 6×10²⁹ dyn cm. This value, which is similar to other values determined for loads of different ages, suggests that the oceanic lithosphere is rigid enough to support applied loads for periods of time of at least several tens of millions of years

Diffusive transport in networks built of containers and tubes

We developed analytical and numerical methods to study a transport of non-interacting particles in large networks consisting of M d-dimensional containers C_1,...,C_M with radii R_i linked together by tubes of length l_{ij} and radii a_{ij} where i,j=1,2,...,M. Tubes may join directly with each other forming junctions. It is possible that some links are absent. Instead of solving the diffusion equation for the full problem we formulated an approach that is computationally more efficient. We derived a set of rate equations that govern the time dependence of the number of particles in each container N_1(t),N_2(t),...,N_M(t). In such a way the complicated transport problem is reduced to a set of M first order integro-differential equations in time, which can be solved efficiently by the algorithm presented here. The workings of the method have been demonstrated on a couple of examples: networks involving three, four and seven containers, and one network with a three-point junction. Already simple networks with relatively few containers exhibit interesting transport behavior. For example, we showed that it is possible to adjust the geometry of the networks so that the particle concentration varies in time in a wave-like manner. Such behavior deviates from simple exponential growth and decay occurring in the two container system.Comment: 21 pages, 18 figures, REVTEX4; new figure added, reduced emphasis on graph theory, additional discussion added (computational cost, one dimensional tubes

Researching ‘bogus’ asylum seekers, ‘illegal’ migrants and ‘crimmigrants’

Both immigration and criminal laws are, at their core, systems of inclusion and exclusion. They are designed to determine whether and how to include individuals as members of society or exclude them from it, thereby, creating insiders and outsiders (Stumpf 2006). Both are designed to create distinct categories of people — innocent versus guilty, admitted versus excluded or, as majority would say, ‘legal’ versus ‘illegal’ (Stumpf 2006). Viewed in that light, perhaps it is not surprising that these two areas of law have become inextrica- bly connected in the official discourses. When politicians and policy makers (and also law enforcement authorities and tabloid press) seek to raise the barriers for non-citizens to attain membership in society, it is unremarkable that they turn their attention to an area of the law that similarly func- tions to exclude the ‘other’ — transforming immigrants into ‘crimmigrants’.1 As a criminological researcher one then has to rise up to the challenges of disentangling these so-called officially constructed (pseudo) realities, and breaking free from a continued dominance of authoritative discourses, and developing an alternative understanding of ‘crimmigration’ by connecting the processes of criminal is ation and ‘other ing’ with poverty, xe no-racism and other forms of social exclusion (see Institute of Race Relations 1987; Richmond 1994; Fekete 2001; Bowling and Phillips 2002; Sivanandan 2002; Weber and Bowling 2004)