DNALinux Virtual Desktop Edition

The new version of DNALinux (VDE) is presented. DNALinux VDE is a departure from traditional distributions since it uses a virtual machine to bundle together the operating system and bioinformatics applications. The main advantage of this approach is that a virtualized environment doesn't affect a installed system. With a virtual machine a Linux system can be run under a Windows system, provided that the virtual machine player is installed. The included programs are listed and specifications to add more programs are explained. We believe that DNALinux could be used as a standardized virtual machine for learning, using, developing and testing bioinformatics applications

Inference and estimation in small sample dynamic panel data models

We study the finite sample properties of the most important methods of estimation of dynamic panel data models in a special class of small samples: a two-sided small sample (i.e., a sample in which the time dimension is not that short but the cross-section dimension is not that large). This case is encountered increasingly in applied work. Our main results are the following: the estimator proposed by Kiviet (1995) outperforms all other estimators considered in the literature. However, standard statistical inference is not valid for any of them. Thus, to assess the true sample variability of the parameter estimates, bootstrap standard errors have to be computed. We find that standard bootstrapping techniques work well except when the autoregressive parameter is close to one. In this last case, the best available solution is to estimate standard errors by means of the Grid-t bootstrap estimator due to Hansen (1999).

Future of Refrigeration Efficiency and Utility

Refrigeration has come a long way from ice boxes to the modern kitchen fridges we possess today. It now requires no more than electricity to preserve food, and many of them use water to produce ice that is readily available at the press of a button. What could be better than that? Well, there are signs as to what the future may hold for the efficiency and utility of this precious technology. Recently prototypes with new built in features and higher efficiency are being built. Examples of these include an added planter box which grows garden plants in controlled conditions, and the implementation of magnetic refrigeration which theoretically might have a higher efficiency than most commercially available fridges. This project will discuss these emerging ideas to advance refrigeration in detail and research just how close they are to becoming part of day to day life

Statistical repulsion/attraction of electrons in graphene in a magnetic field

The aim of this work is to describe the thermodynamic properties of an electron gas in graphene placed in a constant magnetic field. The electron gas is constituted by $N$ Bloch electrons in the long wavelength approximation. The partition function is analyzed in terms of a perturbation expansion of the dimensionless constant $(\sqrt{eB}L)^{-1}$. The statistical repulsion/attraction potential for electrons in graphene is obtained in the respective case in which antisymmetric/symmetric states in the coordinates are chosen. Thermodynamic functions are computed for different orders in the perturbation expansion and the different contributions are compared for symmetric and antisymmetric states, showing remarkable differences between them due to the spin exchange correlation. A detailed analysis of the statistical potential is done, showing that, although electrons satisfy Fermi statistics, attractive potential at some interparticle distances can be found.Comment: Physica B, 201

Valley properties of doped graphene in a magnetic field

The aim of this work is to describe the electronic properties of graphene in a constant magnetic field in the long wavelength approximation with random binary disorder, by solving the Soven equation self-consistently. Density of state contributions for different valleys in each sublattice sites are obtained for different values of magnetic field strength showing remarkable differences between K and K' valleys. A band gap is obtained by an asymmetric on-site impurity concentration and the graphene electrons acquire an anomalous magnetic moment, which is opposite in different valleys, which depend highly in the interplay between the impurity band, the band edges and the broadening of the Landau levels. In turn, magnetization as a function of B for different on-site random impurities is computed showing that by decreasing the on-site impurity energy values, maximum magnetization is shifted towards higher values of B which can be used to create and manipulate polarized valley currents. Finally, conductivity and local vertex function are obtained as a function of energy showing that scattering contributions from A and B sublattices differ significantly. Effective medium local two-irreducible vertex is computed showing that scattering from sublattices A and B do not contribute equally, which can be related to weak anti-localization. From these results, it could be possible to explore how the valley pseudospin can be used to create polarized currents by populating asymmetrically the sublattice sites, where the population can be tuned with the applied magnetic field strength

Dynamical diffusion and renormalization group equation for the Fermi velocity in doped graphene

The aim of this work is to study the electron transport in graphene with impurities by introducing a generalization of linear response theory for linear dispersion relations and spinor wave functions. Current response and density response functions are derived and computed in the Boltzmann limit, showing that in the former case, a minimum conductivity appears in the no-disorder limit. In turn, from the generalization of both functions, an exact relation can be obtained that relates both. Combining this result with the relation given by the continuity equation, it is possible to obtain general functional behavior of the diffusion pole. Finally, a dynamical diffusion is computed in the quasistatic limit using the definition of relaxation function. A lower cutoff must be introduced to regularize infrared divergences, which allow us to obtain a full renormalization group equation for the Fermi velocity, which is solved up to order O(h^2).Comment: 20 pages, 2 figure