Dark Matter Halo Mergers I: Dependence on Environment & Redshift Evolution

This paper presents a study of the specific merger rate as a function of group membership, local environment, and redshift in a very large, $500h^{-1} Mpc$, cosmological N-body simulation, the \textit{Millennium Simulation}. The goal is to provide environmental diagnostics of major merger populations in order to test simulations against observations and provide further constraints on major merger driven galaxy evolution scenarios. A halo sample is defined using the maximum circular velocity, which is both well defined for subhalos and closely correlated with galaxy luminosity. Subhalos, including the precursors of major mergers, are severely tidally stripped. Major mergers between subhalos are therefore extremely rare. Tidal stripping also suppresses dynamical friction, resulting in long major merger time scales when the more massive halo does not host other subhalos. In contrast, when other subhalos are present major merger time scales are several times shorter. This enhancement is likely due to inelastic unbound collisions between subhalos. Following these results, we predict that major mergers in group environments are dominated by mergers involving the central galaxy, that the specific merger rate is suppressed in groups, and that the frequency of fainter companions is enhanced for mergers and their remnants. We also observe an `assembly bias' in the major merger rate in that mergers of galaxy-like halos are slightly suppressed in overdense environments while mergers of group-like halos are slightly enhanced. A dynamical explanation for this trend is advanced which calls on both tidal effects and interactions between bound halos beyond the virial radii of locally dynamically dominant halos.Comment: 44 pages, 8 figures, Preprint Submitted to Ap

Spectral and Transport Properties of d-Wave Superconductors With Strong Impurities

One of the remarkable features of disordered d-wave superconductors is strong sensitivity of long range properties to the microscopic realization of the disorder potential. Particularly rich phenomenology is observed for the -- experimentally relevant -- case of dilute distributions of isolated impurity centers. Building on earlier diagrammatic analyses, the present paper derives and analyses a low energy effective field theory of this system. Specifically, the results of previous diagrammatic T-matrix approaches are extended into the perturbatively inaccessible low energy regimes, and the long range (thermal) transport behaviour of the system is discussed. It turns out that in the extreme case of a half-filled tight binding band and infinitely strong impurities (impurities at the unitary limit), the system is in a delocalized phase.Comment: 14 pages, two figures include

Transition from localized to extended eigenstates in the ensemble of power-law random banded matrices

We study statistical properties of the ensemble of large $N\times N$ random matrices whose entries $H_{ij}$ decrease in a power-law fashion $H_{ij}\sim|i-j|^{-\alpha}$. Mapping the problem onto a nonlinear $\sigma-$model with non-local interaction, we find a transition from localized to extended states at $\alpha=1$. At this critical value of $\alpha$ the system exhibits multifractality and spectral statistics intermediate between the Wigner-Dyson and Poisson one. These features are reminiscent of those typical for the mobility edge of disordered conductors. We find a continuous set of critical theories at $\alpha=1$, parametrized by the value of the coupling constant of the $\sigma-$model. At $\alpha>1$ all states are expected to be localized with integrable power-law tails. At the same time, for $1<\alpha<3/2$ the wave packet spreading at short time scale is superdiffusive: $\langle |r|\rangle\sim t^{\frac{1}{2\alpha-1}}$, which leads to a modification of the Altshuler-Shklovskii behavior of the spectral correlation function. At $1/2<\alpha<1$ the statistical properties of eigenstates are similar to those in a metallic sample in $d=(\alpha-1/2)^{-1}$ dimensions. Finally, the region $\alpha<1/2$ is equivalent to the corresponding Gaussian ensemble of random matrices $(\alpha=0)$. The theoretical predictions are compared with results of numerical simulations.Comment: 19 pages REVTEX, 4 figure

The evolution of substructure II: linking dynamics to environment

We present results from a series of high-resolution N-body simulations that focus on the formation and evolution of eight dark matter halos, each of order a million particles within the virial radius. We follow the time evolution of hundreds of satellite galaxies with unprecedented time resolution, relating their physical properties to the differing halo environmental conditions. The self-consistent cosmological framework in which our analysis was undertaken allows us to explore satellite disruption within live host potentials, a natural complement to earlier work conducted within static potentials. Our host halos were chosen to sample a variety of formation histories, ages, and triaxialities; despite their obvious differences, we find striking similarities within the associated substructure populations. Namely, all satellite orbits follow nearly the same eccentricity distribution with a correlation between eccentricity and pericentre. We also find that the destruction rate of the substructure population is nearly independent of the mass, age, and triaxiality of the host halo. There are, however, subtle differences in the velocity anisotropy of the satellite distribution. We find that the local velocity bias at all radii is greater than unity for all halos and this increases as we move closer to the halo centre, where it varies from 1.1 to 1.4. For the global velocity bias we find a small but slightly positive bias, although when we restrict the global velocity bias calculation to satellites that have had at least one orbit, the bias is essentially removed.Comment: 14 pages, 14 figures, MNRAS in pres

Diffusion in a Random Velocity Field: Spectral Properties of a Non-Hermitian Fokker-Planck Operator

We study spectral properties of the Fokker-Planck operator that describes particles diffusing in a quenched random velocity field. This random operator is non-Hermitian and has eigenvalues occupying a finite area in the complex plane. We calculate the eigenvalue density and averaged one-particle Green's function, for weak disorder and dimension d>2. We relate our results to the time-evolution of particle density, and compare them with numerical simulations.Comment: 4 pages, 2 figure

Random Dirac Fermions and Non-Hermitian Quantum Mechanics

We study the influence of a strong imaginary vector potential on the quantum mechanics of particles confined to a two-dimensional plane and propagating in a random impurity potential. We show that the wavefunctions of the non-Hermitian operator can be obtained as the solution to a two-dimensional Dirac equation in the presence of a random gauge field. Consequences for the localization properties and the critical nature of the states are discussed.Comment: 5 pages, Latex, 1 figure, version published in PR

Freezing of dynamical exponents in low dimensional random media

A particle in a random potential with logarithmic correlations in dimensions $d=1,2$ is shown to undergo a dynamical transition at $T_{dyn}>0$. In $d=1$ exact results demonstrate that $T_{dyn}=T_c$, the static glass transition temperature, and that the dynamical exponent changes from $z(T)=2 + 2 (T_c/T)^2$ at high temperature to $z(T)= 4 T_c/T$ in the glass phase. The same formulae are argued to hold in $d=2$. Dynamical freezing is also predicted in the 2D random gauge XY model and related systems. In $d=1$ a mapping between dynamics and statics is unveiled and freezing involves barriers as well as valleys. Anomalous scaling occurs in the creep dynamics.Comment: 5 pages, 2 figures, RevTe

Statistics of delay times in mesoscopic systems as a manifestation of eigenfunction fluctuations

We reveal a general explicit relation between the statistics of delay times in one-channel reflection from a mesoscopic sample of any spatial dimension and the statistics of the eigenfunction intensities in its closed counterpart. This opens a possibility to use experimentally measurable delay times as a sensitive probe of eigenfunction fluctuations. For the particular case of quasi-one dimensional geometry of the sample we use an alternative technique to derive the probability density of partial delay times for any number of open channels.Comment: 12 pages; published version with updated reference

Approaches to Educational Programs Modeling, Design and Implementation for Continuous Training of Various Experts

This article describes an approach to model, construct and implement multilevel system of continuous educational programs. The training content is determined by the system of generalized professional competencies. The educational levels correspond to the competency levels. The multilevel system includes five educational levels: primary professional training programs (perhaps at high school), secondary vocational programs (which are transformed into applied bachelor programs), bachelor programs, master programs, and postgraduate programs. This multi-level educational system may be implemented effectively using the fractal model of regional educational structures. The fractal model is based on self-similarity, self-organization and self-development. This implemented educational system makes possible to use individual learning tracks both in one educational program and during the transition between educational levels. DOI: 10.5901/mjss.2015.v6n2s3p14

Association of the HTR2A T102C SNP with Weight Gain and Changes in Biochemical Markers in Patients Receiving Antipsychotics

The purpose of our research was to study the association of the HTR2A T102C (rs6313) SNP with anthropometric and biochemical markers in patients treated with typical and atypical antipsychotics in monotherapy mode. Materials and methods: One hundred and seventeen white inpatients (95 men and 22 women) with F2 disorders (ICD-10, 1995) were enrolled in the study. All patients were divided into two groups by the antipsychotic class with which they were treated (Group 1 included 40 patients treated with typical antipsychotics; Group 2 included 77 patients treated with atypical antipsychotics) and two subgroups by weight change criteria during the study (Subgroup 1 included patients with weight change >6%; Subgroup 2 included patients with weight change <6%). The following examinations were performed: physical examination, anthropometric measurements (BMI. WC, TC), clinical examination, blood test (ALT, AST, FPG, VLDL-C, LDL-C, HDL-C, total cholesterol, triglycerides, total protein, albumin, creatinine, uric acid, carbamide), and genotyping for the HTR2A T102C (rs6313) SNP. Results: There were no statistically significant differences in the distribution of genotypes of the HTR2A T102C (rs6313) SNP between Group 1 and Group 2 (P>0.05). Kruskal-Wallis one-way analysis of variance between subgroups showed statistically significant differences between carbamide levels in the second visit in Group 2 (P=0.02). A Dunn post hoc test with Bonferroni adjustment showed statistically significant differences between TT and CT genotypes of the HTR2A T102C SNP: carbamide level was greater in TT carriers (P=0.02). The strength of associations and risks between alleles of the HTR2A T102C SNP and antipsychotic-induced weight change were as follows: ORC=0.49; CIC [0.25; 0.95]; RRC=0.58 CIC [0.35; 0.97]; ORT=2.03; CIT [1.05; 3.94]; RRT=1.7 CIT [1.02; 2.81]. Conclusion: Our results of the pilot pharmacogenetic studies show an association of the T allele carriage of the HTR2A T102C SNP with risk of antipsychotic-induced weight gain. The continuation of this study and an increase in the sample size will allow establishing valid pharmacogenetic markers for the risk of antipsychotic-induced weight gain