Suppression of small scale dynamo action by an imposed magnetic field

Non-helical hydromagnetic turbulence with an externally imposed magnetic field is investigated using direct numerical simulations. It is shown that the imposed magnetic field lowers the spectral magnetic energy in the inertial range. This is explained by a suppression of the small scale dynamo. At large scales, however, the spectral magnetic energy increases with increasing imposed field strength for moderately strong fields, and decreases only slightly for even stronger fields. The presence of Alfven waves is explicitly confirmed by monitoring the evolution of magnetic field and velocity at one point. The frequency omega agrees with vA k1, where vA is the Alfven speed and k1 is the smallest wavenumber in the box.Comment: Final version (7 pages

The Transcriptional Landscape of Marek’s Disease Virus in Primary Chicken B Cells Reveals Novel Splice Variants and Genes

Marek’s disease virus (MDV) is an oncogenic alphaherpesvirus that infects chickens and poses a serious threat to poultry health. In infected animals, MDV efficiently replicates in B cells in various lymphoid organs. Despite many years of research, the viral transcriptome in primary target cells of MDV remained unknown. In this study, we uncovered the transcriptional landscape of the very virulent RB1B strain and the attenuated CVI988/Rispens vaccine strain in primary chicken B cells using high-throughput RNA-sequencing. Our data confirmed the expression of known genes, but also identified a novel spliced MDV gene in the unique short region of the genome. Furthermore, de novo transcriptome assembly revealed extensive splicing of viral genes resulting in coding and non-coding RNA transcripts. A novel splicing isoform of MDV UL15 could also be confirmed by mass spectrometry and RT-PCR. In addition, we could demonstrate that the associated transcriptional motifs are highly conserved and closely resembled those of the host transcriptional machinery. Taken together, our data allow a comprehensive re-annotation of the MDV genome with novel genes and splice variants that could be targeted in further research on MDV replication and tumorigenesis

Inertial range scaling in numerical turbulence with hyperviscosity

Numerical turbulence with hyperviscosity is studied and compared with direct simulations using ordinary viscosity and data from wind tunnel experiments. It is shown that the inertial range scaling is similar in all three cases. Furthermore, the bottleneck effect is approximately equally broad (about one order of magnitude) in these cases and only its height is increased in the hyperviscous case--presumably as a consequence of the steeper decent of the spectrum in the hyperviscous subrange. The mean normalized dissipation rate is found to be in agreement with both wind tunnel experiments and direct simulations. The structure function exponents agree with the She-Leveque model. Decaying turbulence with hyperviscosity still gives the usual t^{-1.25} decay law for the kinetic energy, and also the bottleneck effect is still present and about equally strong.Comment: Final version (7 pages

Conductance length autocorrelation in quasi one-dimensional disordered wires

Employing techniques recently developed in the context of the Fokker--Planck approach to electron transport in disordered systems we calculate the conductance length correlation function $$ for quasi 1d wires. Our result is valid for arbitrary lengths L and $\Delta L$. In the metallic limit the correlation function is given by a squared Lorentzian. In the localized regime it decays exponentially in both L and $\Delta L$. The correlation length is proportional to L in the metallic regime and saturates at a value approximately given by the localization length $\xi$ as $L\gg\xi$.Comment: 23 pages, Revtex, two figure

Higher-order thoughts in action : Consciousness as an unconscious re-description process

Peer reviewedPostprin

Effective σ\sigma Model Formulation for Two Interacting Electrons in a Disordered Metal

We derive an analytical theory for two interacting electrons in a $d$--dimensional random potential. Our treatment is based on an effective random matrix Hamiltonian. After mapping the problem on a nonlinear $\sigma$ model, we exploit similarities with the theory of disordered metals to identify a scaling parameter, investigate the level correlation function, and study the transport properties of the system. In agreement with recent numerical work we find that pair propagation is subdiffusive and that the pair size grows logarithmically with time.Comment: 4 pages, revtex, no figure

Targeted multielectrode tDCS increases functional connectivity within the arcuate fasciculus network: An exploratory study and analysis

Non-invasive electrical stimulation can modulate not only targeted local intrinsic brain activity, but also activity in remote, yet connected brain regions. Such modulation of connected regions and/or entire networks may account for some of the treatment-induced changes in complex behaviors and cognitive processes. The current study tested whether strategically-placed electrodes delivering transcranial direct current stimulation (tDCS) to single or several nodal cortical regions within a structurally-defined network, the arcuate fasciculus network (AF-network), have the potential to strengthen functional connectivity between network regions more effectively than a single electrode placed over an individual nodal region within that same network. Concurrent tDCS-MR imaging was utilized to acquire resting-state fMRI while delivering 4 mA of direct current in multiple OFF-ON-OFF epochs with either a single- or multielectrode anodal montage over nodal cortical regions of the AF-network. Multielectrode anodal stimulation significantly changed functional connectivity between ipsilateral AF-network nodes while no single anodal electrode placed over one nodal region of the right AF-network did so. This significant change in functional connectivity was specific to the targeted right AF-network and could not be seen in other unrelated networks in the same hemisphere (e.g., the inferior longitudinal fasciculus). Functional connectivity measures were compared with electric field modeling measures to estimate target engagement. Regional homogeneity of current tangential to the cortical surface of the AF-network-targeted cortical nodes (J tangent) significantly predicted functional connectivity between these cortical nodes. Taking the anatomy and the drivers of a targeted network into account will help advance the efficacy of an intervention and precision medicine in general

Cyclotron modeling phase-resolved infrared spectroscopy of polars I: EF Eridani

We present phase-resolved low resolution infrared spectra of the polar EF Eridani obtained over a period of 2 years with SPEX on the IRTF. The spectra, covering the wavelength range 0.8 to 2.4 microns, are dominated by cyclotron emission at all phases. We use a ``Constant Lambda'' prescription to attempt to model the changing cyclotron features seen in the spectra. A single cyclotron emission component with B = 12.6 MG, and a plasma temperature of kT = 5.0 keV, does a reasonable job in matching the features seen in the H and K bands, but fails to completely reproduce the morphology shortward of 1.6 microns. We find that a two component model, where both components have similar properties, but whose contributions differ with viewing geometry, provides an excellent fit to the data. We discuss the implications of our models and compare them with previously published results. In addition, we show that a cyclotron model with similar properties to those used for modeling the infrared spectra, but with a field strength of B = 115 MG, can explain the GALEX observations of EF Eri.Comment: 25 pages, 5 figures, to appear in Ap