1,095 research outputs found
Islets of Langerhans Are Protected from Inflammatory Cell Recruitment during Reperfusion of Rat Pancreas Grafts
Background: Ischemia/reperfusion (I/R) injury plays a pivotal role in the development of graft pancreatitis, with ischemia time representing one of its crucial factors. However, it is unclear, whether exocrine and endocrine tissue experience similar inflammatory responses during pancreas transplantation (PTx). This study evaluated inflammatory susceptibilities of islets of Langerhans (ILH) and exocrine tissue after different preservation periods during early reperfusion. Methods: PTx was performed in rats following 2 h (2h-I) or 18 h (18h-I) preservation. Leukocyte-endothelial cell interactions (LEI) were analyzed in venules of acinar tissue and ILH in vivo over 2 h reperfusion. Nontransplanted animals served as controls. Tissue samples were analyzed by histomorphometry. Results: In exocrine venules leukocyte rolling predominated in the 2h-I group. In the 18h-I group, additionally, high numbers of adherent leukocytes were found. Histology revealed significant edema formation and leukocyte extravasation in the 18h-I group. Notably, LEI in postcapillary venules of ILH were significantly lower. Leukocyte rolling was only moderately enhanced and few leukocytes were found adherent. Histology revealed minor leukocyte extravasation. Conclusion: Ischemia time contributes decisively to the extent of the I/R-injury in PTx. However, ILH have a significantly lower susceptibility towards I/R, even when inflammatory reactions in adjacent exocrine tissue are evident. Copyright (C) 2010 S. Karger AG, Base
Topological solitons in highly anisotropic two dimensional ferromagnets
e study the solitons, stabilized by spin precession in a classical
two--dimensional lattice model of Heisenberg ferromagnets with non-small
easy--axis anisotropy. The properties of such solitons are treated both
analytically using the continuous model including higher then second powers of
magnetization gradients, and numerically for a discrete set of the spins on a
square lattice. The dependence of the soliton energy on the number of spin
deviations (bound magnons) is calculated. We have shown that the
topological solitons are stable if the number exceeds some critical value
. For and the intermediate values of anisotropy
constant ( is an exchange constant), the soliton
properties are similar to those for continuous model; for example, soliton
energy is increasing and the precession frequency is decreasing
monotonously with growth. For high enough anisotropy we found some fundamentally new soliton features absent for continuous
models incorporating even the higher powers of magnetization gradients. For
high anisotropy, the dependence of soliton energy E(N) on the number of bound
magnons become non-monotonic, with the minima at some "magic" numbers of bound
magnons. Soliton frequency have quite irregular behavior with
step-like jumps and negative values of for some regions of . Near
these regions, stable static soliton states, stabilized by the lattice effects,
exist.Comment: 17 page
Internal Modes and Magnon Scattering on Topological Solitons in 2d Easy-Axis Ferromagnets
We study the magnon modes in the presence of a topological soliton in a 2d
Heisenberg easy-axis ferromagnet. The problem of magnon scattering on the
soliton with arbitrary relation between the soliton radius R and the "magnetic
length" Delta_0 is investigated for partial modes with different values of the
azimuthal quantum numbers m. Truly local modes are shown to be present for all
values of m, when the soliton radius is enough large. The eigenfrequencies of
such internal modes are calculated analytically on limiting case of a large
soliton radius and numerically for arbitrary soliton radius. It is demonstrated
that the model of an isotropic magnet, which admits an exact analytical
investigation, is not adequate even for the limit of small radius solitons,
R<<Delta_0: there exists a local mode with nonzero frequency. We use the data
about local modes to derive the effective equation of soliton motion; this
equation has the usual Newtonian form in contrast to the case of the easy-plane
ferromagnet. The effective mass of the soliton is found.Comment: 33 pages (REVTeX), 12 figures (EPS
Topological phase separation in 2D hard-core Bose-Hubbard system away from half-filling
We suppose that the doping of the 2D hard-core boson system away from
half-filling may result in the formation of multi-center topological defect
such as charge order (CO) bubble domain(s) with Bose superfluid (BS) and extra
bosons both localized in domain wall(s), or a {\it topological} CO+BS {\it
phase separation}, rather than an uniform mixed CO+BS supersolid phase.
Starting from the classical model we predict the properties of the respective
quantum system. The long-wavelength behavior of the system is believed to
remind that of granular superconductors, CDW materials, Wigner crystals, and
multi-skyrmion system akin in a quantum Hall ferromagnetic state of a 2D
electron gas.Comment: 6 pages, 1 figur
Soliton-Magnon Scattering in Two-Dimensional Isotropic Ferromagnets
It is studied the scattering of magnons by the 2d topological
Belavin-Polyakov soliton in isotropic ferromagnet. Analytical solutions of the
scattering problem are constructed: (i) exactly for any magnon wave vectors for
the partial wave with the azimuthal number m=1 (translational mode), and (ii)
in the long- and short-wave limits for the rest modes. The magnon mode
frequencies are found for the finite size magnets. An effective equation of the
soliton motion is constructed. The magnon density of states, connected with the
soliton-magnon interaction, is found in a long-wave approximation.Comment: 4 pages, REVTe
Inhomogeneity of the intrinsic magnetic field in superconducting YBa2Cu3OX compounds as revealed by rare-earth EPR-probe
X-band electron paramagnetic resonance on doped Er3+ and Yb3+ ions in
Y0.99(Yb,Er)0.01Ba2Cu3OX compounds with different oxygen contents in the wide
temperature range (4-120)K have been made. In the superconducting species, the
strong dependencies of the linewidth and resonance line position from the sweep
direction of the applied magnetic field are revealed at the temperatures
significantly below TC. The possible origins of the observed hysteresis are
analyzed. Applicability of the presented EPR approach to extract information
about the dynamics of the flux-line lattice and critical state parameters
(critical current density, magnetic penetration depth, and characteristic
spatial scale of the inhomogeneity) is discussedComment: 17 pages, 5 Figures. Renewed versio
Recommended vaccination schedules for a comprehensive dairy herd health program
The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311
Impact of pollen on throughfall biochemistry in European temperate and boreal forests
Pollen is known to affect forest throughfall biochemistry, but underlying mechanisms are not fully understood. We used generalized additive mixed modelling to study the relationship between long-term series of measured throughfall fluxes in spring (AprilâJune) at forest plots and corresponding airborne pollen concentrations (Seasonal Pollen Integral, SPIn) from nearby aerobiological monitoring stations. The forest plots were part of the intensive long term monitoring (Level II) network of the UNECE International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) with dominant tree genera Fagus, Quercus, Pinus and Picea, and were distributed all across Europe. We also conducted a 7-day laboratory dissolution experiment with bud scales and flower stalks of European beech (Fagus sylvatica L.), pollen of beech, common oak (Quercus robur L.), silver birch (Betula pendula L.), Scots pine (Pinus sylvestris L.), Corsican pine (Pinus nigra Arnold ssp. laricio (Poiret) Maire), Norway spruce (Picea abies (L.) Karst.) and sterilized pollen of silver birch in a nitrate (NO3--N) solution (11.3 mg N L-1). Throughfall fluxes of potassium (K+), ammonium (NH4+-N), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) showed a positive relationship with SPIn whereas NO3--N fluxes showed a negative relationship with SPIn. In years with massive seed production of beech and oak SPIn and throughfall fluxes of K+ and DOC were higher, but fluxes of NO3--N were lower. The experiment broadly confirmed the findings based on field data. Within two hours, pollen released large quantities of K+, phosphate, DOC and DON, and lesser amounts of sulphate, sodium and calcium. After 24-48 hours, NO3--N started to disappear, predominantly in the treatments with broadleaved pollen, while concentrations of nitrite and NH4+-N increased. At the end of the experiment, the inorganic nitrogen (DIN) was reduced, presumably because it was lost as gaseous nitric oxide (NO). There was no difference for sterilized pollen, indicating that the involvement of microbial activity was limited in above N transformations. Our results show that pollen dispersal might be an overlooked factor in forest nutrient cycling and might induce complex canopy N transformations, although the net-impact on N throughfall fluxes is rather lo
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