Gravitational Mesoscopic Constraints in Cosmological Dark Matter Halos

We present an analysis of the behaviour of the `coarse-grained' (`mesoscopic') rank partitioning of the mean energy of collections of particles composing virialized dark matter halos in a Lambda-CDM cosmological simulation. We find evidence that rank preservation depends on halo mass, in the sense that more massive halos show more rank preservation than less massive ones. We find that the most massive halos obey Arnold's theorem (on the ordering of the characteristic frequencies of the system) more frequently than less massive halos. This method may be useful to evaluate the coarse-graining level (minimum number of particles per energy cell) necessary to reasonably measure signatures of `mesoscopic' rank orderings in a gravitational system.Comment: LaTeX, 15 pages, 3 figures. Accepted for publication in Celestial Mechanics and Dynamical Astronomy Journa

The spin and charge gaps of the half-filled N-leg Kondo ladders

In this work, we study N-leg Kondo ladders at half-filling through the density matrix renormalization group. We found non-zero spin and charge gaps for any finite number of legs and Kondo coupling $J>0$. We also show evidence of the existence of a quantum critical point in the two dimensional Kondo lattice model, in agreement with previous works. Based on the binding energy of two holes, we did not find evidence of superconductivity in the 2D Kondo lattice model close to half-filling.Comment: 4 pages, 1 table, 3 fig

DMRG studies of the effect of constraint release on the viscosity of polymer melts

The scaling of the viscosity of polymer melts is investigated with regard to the molecular weight. We present a generalization of the Rubinstein-Duke model, which takes constraint releases into account and calculate the effects on the viscosity by the use of the Density Matrix Renormalization Group (DMRG) algorithm. Using input from Rouse theory the rates for the constraint release are determined in a self consistent way. We conclude that shape fluctuations of the tube caused by constraint release are not a likely candidate for improving Doi's crossover theory for the scaling of the polymer viscosity.Comment: 6 pages, 8 figure

The structure of the shell and polar plugs of the egg of the whipworm, Trichuris trichiura (Nematoda : Trichuridae) from the Samango monkey (Cercopithecus albogularis)

The structure of the shell of the egg of Trichuris trichiura was examined using light microscopy as well as scanning and transmission electron microscopy. The results confirmed its three-layered structure and provided evidence that the cores of the polar plugs, which could be seen to be extensions of the shell's middle layer, could be lost en bloc, either mechanically or chemically, and in this way probably provided an exit for the first stage larva at hatching.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

Numerical renormalization group study of the 1D t-J model

The one-dimensional (1D) $t-J$ model is investigated using the density matrix renormalization group (DMRG) method. We report for the first time a generalization of the DMRG method to the case of arbitrary band filling and prove a theorem with respect to the reduced density matrix that accelerates the numerical computation. Lastly, using the extended DMRG method, we present the ground state electron momentum distribution, spin and charge correlation functions. The $3k_F$ anomaly of the momentum distribution function first discussed by Ogata and Shiba is shown to disappear as $J$ increases. We also argue that there exists a density-independent $J_c$ beyond which the system becomes an electron solid.Comment: Wrong set of figures were put in the orginal submissio

Small Fermi surface in the one-dimensional Kondo lattice model

We study the one-dimensional Kondo lattice model through the density matrix renormalization group (DMRG). Our results for the spin correlation function indicate the presence of a small Fermi surface in large portions of the phase diagram, in contrast to some previous studies that used the same technique. We argue that the discrepancy is due to the open boundary conditions, which introduce strong charge perturbations that strongly affect the spin Friedel oscillations.Comment: 5 pages, 7 figure

A survey of solution techniques for the partially observed Markov decision process

We survey several computational procedures for the partially observed Markov decision process (POMDP) that have been developed since the Monahan survey was published in 1982. The POMDP generalizes the standard, completely observed Markov decision process by permitting the possibility that state observations may be noise-corrupted and/or costly. Several computational procedures presented are convergence accelerating variants of, or approximations to, the Smallwood-Sondik algorithm. Finite-memory suboptimal design results are reported, and new research directions involving heuristic search are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44198/1/10479_2005_Article_BF02204836.pd

Oxidation and fragmentation of plastics in a changing environment; from UV-radiation to biological degradation

Understanding the fate of plastics in the environment is of critical importance for the quantitative assessment of the biological impacts of plastic waste. Specially, there is a need to analyze in more detail the reputed longevity of plastics in the context of plastic degradation through oxidation and fragmentation reactions. Photo-oxidation of plastic debris by solar UV radiation (UVR) makes material prone to subsequent fragmentation. The fragments generated following oxidation and subsequent exposure to mechanical stresses include secondary micro- or nanoparticles, an emerging class of pollutants. The paper discusses the UV-driven photo-oxidation process, identifying relevant knowledge gaps and uncertainties. Serious gaps in knowledge exist concerning the wavelength sensitivity and the dose-response of the photo-fragmentation process. Given the heterogeneity of natural UV irradiance varying from no exposure in sediments to full UV exposure of floating, beach litter or air-borne plastics, it is argued that the rates of UV-driven degradation/fragmentation will also vary dramatically between different locations and environmental niches. Biological phenomena such as biofouling will further modulate the exposure of plastics to UV radiation, while potentially also contributing to degradation and/or fragmentation of plastics independent of solar UVR. Reductions in solar UVR in many regions, consequent to the implementation of the Montreal Protocol and its Amendments for protecting stratospheric ozone, will have consequences for global UV-driven plastic degradation in a heterogeneous manner across different geographic and environmental zones. The interacting effects of global warming, stratospheric ozone and UV radiation are projected to increase UV irradiance at the surface in localized areas, mainly because of decreased cloud cover. Given the complexity and uncertainty of future environmental conditions, this currently precludes reliable quantitative predictions of plastic persistence on a global scale

Galactic cannibalism in the galaxy cluster C0337-2522 at z=0.59

According to the galactic cannibalism model, cD galaxies are formed in the center of galaxy clusters by merging of massive galaxies and accretion of smaller stellar systems: however, observational examples of the initial phases of this process are lacking. We have identified a strong candidate for this early stage of cD galaxy formation: a group of five elliptical galaxies in the core of the X-ray cluster C0337-2522 at redshift z=0.59. With the aid of numerical simulations, in which the galaxies are represented by N-body systems, we study their dynamical evolution up to z=0; the cluster dark matter distribution is also described as a N-body system. We find that a multiple merging event in the considered group of galaxies will take place before z=0 and that the merger remnant preserves the Fundamental Plane and the Faber-Jackson relations, while its behavior with respect to the Mbh-sigma relation is quite sensitive to the details of black hole merging [abridged].Comment: 30 pages, 7 figures, MNRAS (accepted