41,202 research outputs found
Specific-heat study for ferromagnetic and antiferromagnetic phases in SrRu_{1-x}Mn_xO3
Low-temperature electronic states in SrRu_{1-x}Mn_xO_3 for x <= 0.6 have been
investigated by means of specific-heat C_p measurements. We have found that a
jump anomaly observed in C_p at the ferromagnetic (FM) transition temperature
for SrRuO_3 changes into a broad peak by only 5% substitution of Mn for Ru.
With further doping Mn, the low-temperature electronic specific-heat
coefficient gamma is markedly reduced from the value at x=0 (33 mJ/K^2 mol), in
connection with the suppression of the FM phase as well as the enhancement of
the resistivity. For x >= 0.4, gamma approaches to ~ 5 mJ/K^2 mol or less,
where the antiferromagnetic order with an insulating feature in resistivity is
generated. We suggest from these results that both disorder and reconstruction
of the electronic states induced by doping Mn are coupled with the magnetic
ground states and transport properties.Comment: 4 pages, 2 figures, submitted to the proceedings of ICM2009
(Karlsruhe
Integrable dispersionless KdV hierarchy with sources
An integrable dispersionless KdV hierarchy with sources (dKdVHWS) is derived.
Lax pair equations and bi-Hamiltonian formulation for dKdVHWS are formulated.
Hodograph solution for the dispersionless KdV equation with sources (dKdVWS) is
obtained via hodograph transformation. Furthermore, the dispersionless
Gelfand-Dickey hierarchy with sources (dGDHWS) is presented.Comment: 15 pages, to be published in J. Phys. A: Math. Ge
New model of calculating the energy transfer efficiency for the spherical theta-pinch device
Ion-beam-plasma-interaction plays an important role in the field of Warm
Dense Matter (WDM) and Inertial Confinement Fusion (ICF). A spherical theta
pinch is proposed to act as a plasma target in various applications including a
plasma stripper cell. One key parameter for such applications is the free
electron density. A linear dependency of this density to the amount of energy
transferred into the plasma from an energy storage was found by C. Teske. Since
the amount of stored energy is known, the energy transfer efficiency is a
reliable parameter for the design of a spherical theta pinch device. The
traditional two models of energy transfer efficiency are based on assumptions
which comprise the risk of systematical errors. To obtain precise results, this
paper proposes a new model without the necessity of any assumption to calculate
the energy transfer efficiency for an inductively coupled plasma device.
Further, a comparison of these three different models is given at a fixed
operation voltage for the full range of working gas pressures. Due to the
inappropriate assumptions included in the traditional models, one owns a
tendency to overestimate the energy transfer efficiency whereas the other leads
to an underestimation. Applying our new model to a wide spread set of operation
voltages and gas pressures, an overall picture of the energy transfer
efficiency results
Dynamics of Vortex Core Switching in Ferromagnetic Nanodisks
Dynamics of magnetic vortex core switching in nanometer-scale permalloy disk,
having a single vortex ground state, was investigated by micromagnetic
modeling. When an in-plane magnetic field pulse with an appropriate strength
and duration is applied to the vortex structure, additional two vortices, i.e.,
a circular- and an anti-vortex, are created near the original vortex core.
Sequentially, the vortex-antivortex pair annihilates. A spin wave is created at
the annihilation point and propagated through the entire element; the relaxed
state for the system is the single vortex state with a switched vortex core.Comment: to appear in Appl. Phys. Let
High energy constraints in the octet SS-PP correlator and resonance saturation at NLO in 1/Nc
We study the octet SS-PP correlator within resonance chiral theory up to the
one-loop level, i.e., up to next-to-leading order in the 1/Nc expansion. We
will require that our correlator follows the power behaviour prescribed by the
operator product expansion at high euclidian momentum. Nevertheless, we will
not make use of short-distance constraints from other observables. Likewise,
the high-energy behaviour will be demanded for the whole correlator, not for
individual absorptive channels. The amplitude is progressively improved by
considering more and more complicated operators in the hadronic lagrangian.
Matching the resonance chiral theory result with chiral perturbation theory at
low energies produces the estimates L_8(mu)^{SU(3)} = (1.0+-0.4)10^-3 and
C_{38}(mu)^{SU(3)} = (8+-5) 10^-6 for mu=770 MeV. The effect of alternative
renormalization schemes is also discussed in the article.Comment: 40 pages, 18 figure
Characterisation of microorganisms responsible for EBPR in a sequencing batch reactor by using the 16S rDNA-DGGE method
Analysis of the bacterial community in the biological phosphorus removal system is propitious to study the phosphorus-removal mechanism. The activated sludge was acclimated through a repeated anaerobic-aerobic process with glucose as carbon source for 2 months and a stable EBPR was established in an SBR. Total phosphate of the wastewater decreased by 12.43 mgE.-1 after 4 h aerobic treatment while total P uptake in the raw sludge was 0.57 mgE.-1 under the same conditions, and the phosphate content of the sludge increased from 1.83% to 6.79%. The protozoa and dominant bacteria of the two sludges were observed by optical and electron microscope. The genomic DNA of samples was extracted as the template and the 16S rDNA genes (V3 region) were amplified; denaturing gradient gel electrophoresis (DGGE) separated these amplified DNA fragments with the denaturant from 35% to 70%. The DGGE profiles showed that the raw sludge, acclimated sludge and dominant bacteria in the acclimated sludge had different band patterns. The results indicated that micro-organisms were selected by the repeated anaerobic-aerobic process and some non-phosphorus accumulating organisms were eliminated. The cultured strains obtained from acclimated sludges were purified and their DNA was amplified using F27 and R1522 to 1.5 kb; the gene sequences were located on the GenBank and they were identified as Acidovorax sp.BSB421 and Sphingomonas sp.SA-3
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