3,620 research outputs found
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 .
In the metallic limit the correlation function is given by a squared
Lorentzian. In the localized regime it decays exponentially in both L and
. The correlation length is proportional to L in the metallic regime
and saturates at a value approximately given by the localization length
as .Comment: 23 pages, Revtex, two figure
Diagnostic utility of cardiac MRI in clinical evaluation of cardiac masses with histopathological correlation
Higher-order thoughts in action : Consciousness as an unconscious re-description process
Peer reviewedPostprin
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
Effective Model Formulation for Two Interacting Electrons in a Disordered Metal
We derive an analytical theory for two interacting electrons in a
--dimensional random potential. Our treatment is based on an effective
random matrix Hamiltonian. After mapping the problem on a nonlinear
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
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
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