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

Systemic inflammation and residual viraemia in HIV-positive adults on protease inhibitor monotherapy: a cross-sectional study.

Increased levels of markers of systemic inflammation have been associated with serious non-AIDS events even in patients on fully suppressive antiretroviral therapy. We explored residual viremia and systemic inflammation markers in patients effectively treated with ritonavir-boosted protease inhibitor monotherapy (PImono)

Beyond mean-field bistability in driven-dissipative lattices: bunching-antibunching transition and quantum simulation

In the present work we investigate the existence of multiple nonequilibrium steady states in a coherently driven XY lattice of dissipative two-level systems. A commonly used mean-field ansatz, in which spatial correlations are neglected, predicts a bistable behavior with a sharp shift between low- and high-density states. In contrast one-dimensional matrix product methods reveal these effects to be artifacts of the mean-field approach, with both disappearing once correlations are taken fully into account. Instead, a bunching-antibunching transition emerges. This indicates that alternative approaches should be considered for higher spatial dimensions, where classical simulations are currently infeasible. Thus we propose a circuit QED quantum simulator implementable with current technology to enable an experimental investigation of the model considered

Investigación mexicana significativa en Ciencias de la Salud 1999-2004 : un análisis bibliométrico

The economic conditions in Mexico have contributed to the impoverishment of its population and, consequently a worsening of their health. Therefore, if research contributes to development, the study of significant research is justified, that is to say research whose results appear in core journals, a principle commonly known as the Bradford Law. The purpose of this study is to determine what has been the scientific growth in order to be able to assume, with empirical evidence, that Mexican researchers have overcome difficulties in order to publish in the most relevant journals, i.e. the most significant ones. Empirical data was built on the basis of the journal lists compiled by Garfield, which comprise of 200 journals that reached the highest levels of impact over a period of 15 years. A total of 155 health science journals were included in the analysis conducted through the Web of Science. A total of 1,293 records published between 1999 and 2004 were identified from a total of 829,400 papers that appeared in those journals and in within the same period globally. 80 % of the significant research carried out in Mexico was concentrated in two entities of the country. It was found that health research is the responsibility of public institutions, mainly academia. Also, that the most active disciplines were biochemistry and molecular biology, neurosciences, general and internal medicine, immunology and microbiology. The conclusion reached is that Mexican researchers have overcome the difficulties related with publishing papers in the core journals. However, Mexican institutions still have to strengthen themselves further in order for the research they carry out be reflected in papers that will take them into a market of visible science, that counts

Magnetodielectric coupling of infrared phonons in single crystal Cu2_{2}OSeO3_{3}

Reflection and transmission as a function of temperature have been measured on a single crystal of the magnetoelectric ferrimagnetic compound Cu$_{2}$OSeO$_{3}$ utilizing light spanning the far infrared to the visible portions of the electromagnetic spectrum. The complex dielectric function and optical properties were obtained via Kramers-Kronig analysis and by fits to a Drude-Lortentz model. The fits of the infrared phonons show a magnetodielectric effect near the transition temperature ($T_{c}\sim 60$~K). Assignments to strong far infrared phonon modes have been made, especially those exhibiting anomalous behavior around the transition temperature

Community detection in complex networks using Extremal Optimization

We propose a novel method to find the community structure in complex networks based on an extremal optimization of the value of modularity. The method outperforms the optimal modularity found by the existing algorithms in the literature. We present the results of the algorithm for computer simulated and real networks and compare them with other approaches. The efficiency and accuracy of the method make it feasible to be used for the accurate identification of community structure in large complex networks.Comment: 4 pages, 4 figure

Modelling diffusion of innovations in a social network

A new simple model of diffusion of innovations in a social network with upgrading costs is introduced. Agents are characterized by a single real variable, their technological level. According to local information agents decide whether to upgrade their level or not balancing their possible benefit with the upgrading cost. A critical point where technological avalanches display a power-law behavior is also found. This critical point is characterized by a macroscopic observable that turns out to optimize technological growth in the stationary state. Analytical results supporting our findings are found for the globally coupled case.Comment: 4 pages, 5 figures. Final version accepted in PR