559 research outputs found
Ceramide-induced disruption of endothelial nitric oxide synthase dimerization in bovine aortic endothelial cells (BAECs) is not secondary to peroxynitrite formation
posterAn estimated 23.6 million individuals in the United States have diabetes and of those 90-95% have type II diabetes. Cardiovascular complications (e.g., hypertension and vascular dysfunction) are four-fold more prevalent in patients with type II diabetes. To gain insight into mechanisms responsible for ceramide-induced endothelial dysfunction, BAECs were incubated with palmitate to precipitate endogenous ceramide biosynthesis
Moving Difference (MDIFF) Non-adiabatic Rapid Sweep (NARS) EPR of Copper(II)
Non-adiabatic rapid sweep (NARS) EPR spectroscopy has been introduced for application to nitroxide-labeled biological samples (Kittell et al., 2011). Displays are pure absorption, and are built up by acquiring data in spectral segments that are concatenated. In this paper we extend the method to frozen solutions of copper-imidazole, a square planar copper complex with four in-plane nitrogen ligands. Pure absorption spectra are created from concatenation of 170 5-gauss segments spanning 850 G at 1.9 GHz. These spectra, however, are not directly useful since nitrogen superhyperfine couplings are barely visible. Application of the moving difference (MDIFF) algorithm to the digitized NARS pure absorption spectrum is used to produce spectra that are analogous to the first harmonic EPR. The signal intensity is about four times higher than when using conventional 100 kHz field modulation, depending on line shape. MDIFF not only filters the spectrum, but also the noise, resulting in further improvement of the SNR for the same signal acquisition time. The MDIFF amplitude can be optimized retrospectively, different spectral regions can be examined at different amplitudes, and an amplitude can be used that is substantially greater than the upper limit of the field modulation amplitude of a conventional EPR spectrometer, which improves the signal-to-noise ratio of broad lines
The F-CHROMA grid of 1D RADYN flare models
Context: Solar flares are the result of the sudden release of magnetic energy
in the corona. Much of this energy goes into accelerating charged particles to
high velocity. These particles travel along the magnetic field and the energy
is dissipated when the density gets high enough, primarily in the solar
chromosphere. Modelling this region is difficult because the radiation energy
balance is dominated by strong, optically thick spectral lines.
Aims: Our aim is to provide the community with realistic simulations of a
flaring loop with an emphasis on the detailed treatment of the chromospheric
energy balance. This will enable a detailed comparison of existing and upcoming
observations with synthetic observables from the simulations, thereby
elucidating the complex interactions in a flaring chromosphere.
Methods: We used the 1D radiation hydrodynamics code RADYN to perform
simulations of the effect of a beam of electrons injected at the apex of a
solar coronal loop. A grid of models was produced, varying the total energy
input, the steepness, and low-energy cutoff of the beam energy spectrum.
Results: The full simulation results for a grid of models are made available
online. Some general properties of the simulations are discussed.Comment: 11 pages, 9 figures. Accepted for publication in Astronomy &
Astrophysic
Intraspecific and biogeographical variation in foliar fungal communities and pathogen damage of native and invasive Phragmites australis
AimRecent research has highlighted that the relationship between species interactions and latitude can differ between native and invasive plant taxa, generating biogeographical heterogeneity in community resistance to plant invasions. In the first study with foliar pathogens, we tested whether co‐occurring native and invasive lineages of common reed (Phragmites australis) exhibit non‐parallel latitudinal gradients in foliar fungal communities, pathogen susceptibility and damage, and whether these biogeographical patterns can influence the success of invasion.LocationNorth America.Time period2015–2017.Major taxa studiedPerennial grass P. australis.MethodsWe surveyed 35 P. australis field populations, spanning 17° latitude and comprising four phylogeographical lineages, including one endemic to North America and one invasive from Europe. For each population, we quantified the percentage of leaf pathogen damage and cultured fungi from diseased leaves, which we identified using molecular tools. To assess whether latitudinal gradients in pathogen damage had a genetic basis, we inoculated plants from 73 populations with four putative pathogens in a complementary common garden experiment and measured P. australis susceptibility (i.e., diseased leaf area).ResultsWe isolated 84 foliar fungal taxa. Phragmites australis lineage influenced fungal community composition but not diversity. Despite the invasive European P. australis lineage being the least susceptible to three of the four pathogens tested in the common garden experiment, pathogen damage in the field was similar between native and invasive lineages, providing no evidence that release from foliar pathogens contributes to the success of invasion. Genetically based latitudinal gradients in pathogen susceptibility observed in the common garden were isolate specific and obscured by local environmental conditions in the field, where pathogen damage was threefold higher for northern compared with southern populations, regardless of lineage.Main conclusionsOur results highlight that host plant lineage and genetically based biogeographical gradients strongly influence foliar fungal communities and pathogen susceptibility, but do not translate to patterns of pathogen damage observed in the field.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155999/1/geb13097.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155999/2/geb13097_am.pd
Exclusive processes in electron - ion collisions
The exclusive processes in electron-ion () interactions are an important
tool to investigate the QCD dynamics at high energies as they are in general
driven by the gluon content of the target, which is strongly subject to parton
saturation effects. In this paper we compute the cross sections for the
exclusive vector meson production as well as the deeply virtual Compton
scattering (DVCS) relying on the color dipole approach and considering the
numerical solution of the Balitsky-Kovchegov equation including running
coupling corrections (rcBK). The production cross sections obtained with the
rcBK solution and bCGC parametrization are very similar, the former being
slightly larger.Comment: 6 pages, 4 figure
The New F_L Measurement from HERA and the Dipole Model
From the new measurement of F_L at HERA we derive fixed-Q^2 averages
. We compare these with bounds which are rigorous in the framework of
the standard dipole picture. The bounds are sharpened by including information
on the charm structure function F_2^(c). Within the experimental errors the
bounds are respected by the data. But for 3.5 GeV^2 <= Q^2 <= 20 GeV^2 the
central values of the data are close to and in some cases even above the
bounds. Data on F_L/F_2 significantly exceeding the bounds would rule out the
standard dipole picture at these kinematic points. We discuss, furthermore, how
data respecting the bounds but coming close to them can give information on
questions like colour transparency, saturation and the dependencies of the
dipole-proton cross section on the energy and the dipole size.Comment: 12 page
On the Energy Dependence of the Dipole-Proton Cross Section in Deep Inelastic Scattering
We study the dipole picture of high-energy virtual-photon-proton scattering.
It is shown that different choices for the energy variable in the dipole cross
section used in the literature are not related to each other by simple
arguments equating the typical dipole size and the inverse photon virtuality,
contrary to what is often stated. We argue that the good quality of fits to
structure functions that use Bjorken-x as the energy variable - which is
strictly speaking not justified in the dipole picture - can instead be
understood as a consequence of the sign of scaling violations that occur for
increasing Q^2 at fixed small x. We show that the dipole formula for massless
quarks has the structure of a convolution. From this we obtain derivative
relations between the structure function F_2 at large and small Q^2 and the
dipole-proton cross section at small and large dipole size r, respectively.Comment: 27 page
Extracting the Distribution Amplitudes of the rho meson from the Color Glass Condensate
We extract the leading twist-2 and subleading twist-3 Distribution Amplitudes
(DAs) of the rho meson using the HERA data on diffractive rho photoproduction.
We do so using several Colour Glass Condensate (CGC) inspired and a Regge
inspired dipole models. We find that our extracted twist-2 DA is not much model
dependent and is consistent with QCD Sum Rules and lattice predictions. The
extracted twist-3 DA is more model dependent but is still consistent with the
Sum Rules prediction.Comment: 21 pages, 10 figures, 3 tables. Section 6 revised, figures 8 and 9
and table 3 updated. Conclusions essentially unchange
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