900 research outputs found
Professionalism and the Millbank Tendency: The Political Sociology of New Labour's employees
This article analyses party employees, one of the most under-researched subjects in the study of British political parties. We draw on a blend of quantitative and qualitative data in order to shed light on the social and political profiles of Labour Party staff, and on the question of their professionalisation. The latter theme is developed through a model derived from the sociology of professions. While a relatively limited proportion of party employees conform to the pure ideal-type of professionalism, a considerably greater number manifest enough of the core characteristics of specialisation, commitment, mobility, autonomy and self-regulation to be reasonably described as 'professionals in pursuit of political outcomes'
Carbonate-hosted methanotrophy represents an unrecognized methane sink in the deep sea
The atmospheric flux of methane from the oceans is largely mitigated through microbially mediated sulphate-coupled methane oxidation, resulting in the precipitation of authigenic carbonates. Deep-sea carbonates are common around active and palaeo-methane seepage, and have primarily been viewed as passive recorders of methane oxidation; their role as active and unique microbial habitats capable of continued methane consumption has not been examined. Here we show that seep-associated carbonates harbour active microbial communities, serving as dynamic methane sinks. Microbial aggregate abundance within the carbonate interior exceeds that of seep sediments, and molecular diversity surveys reveal methanotrophic communities within protolithic nodules and well-lithified carbonate pavements. Aggregations of microbial cells within the carbonate matrix actively oxidize methane as indicated by stable isotope FISH–nanoSIMS experiments and ^(14)CH_4 radiotracer rate measurements. Carbonate-hosted methanotrophy extends the known ecological niche of these important methane consumers and represents a previously unrecognized methane sink that warrants consideration in global methane budgets
Development of high-temperature ferromagnetism in SnO2 and paramagnetism in SnO by Fe doping
We report the development of room-temperature ferromagnetism in chemically synthesized powder samples of Sn1−xFexO2 (0.005≤ x ≤0.05) and paramagnetic behavior in an identically synthesized set of Sn1−xFexO. The ferromagnetic Sn0.99Fe0.01O2 showed a Curie temperature TC=850 K, which is among the highest reported for transition-metal-doped semiconductor oxides. With increasing Fe doping, the lattice parameters of SnO2 decreased and the saturation magnetization increased, suggesting a strong structure-magnetic property relationship. When the Sn0.95Fe0.05O2 was prepared at different temperatures between 200 and 900 °C, systematic changes in the magnetic properties were observed. Combined Mössbauer spectroscopy and magnetometry measurements showed a ferromagnetic behavior in Sn0.95Fe0.05O2 samples prepared at and above 350°C, but the ferromagnetic component decreased gradually as preparation temperature approached 600 °C. All Sn0.95Fe0.05O2 samples prepared above 600 °C were paramagnetic. X-ray photoelectron spectroscopy, magnetometry, and particle induced x-ray emission studies showed that the Fe dopants diffuse towards the surface of the particles in samples prepared at higher temperatures, gradually destroying the ferromagnetism. Mössbauer studies showed that the magnetically ordered Fe3+ spins observed in the Sn0.95Fe0.05O2 sample prepared at 350 °C is only ~24% of the uniformly incorporated Fe3+. No evidence of any iron oxide impurity phases were detected in Sn1−xFexO2 or Sn1−xFexO, suggesting that the emerging magnetic interactions in these systems are most likely related to the properties of the host systems SnO2 and SnO, and their oxygen stoichiometry
63Cu NQR evidence of dimensional crossover to anisotropic 2d regime in S= 1/2 three-leg ladder Sr2Cu3O5
We probed spin-spin correlations up to 725 K with 63Cu NQR in the S= 1/2
three-leg ladder Sr2Cu3O5. We present experimental evidence that below 300 K,
weak inter-ladder coupling causes dimensional crossover of the spin-spin
correlation length \xi from quasi-1d (\xi ~ 1/T) to anisotropic 2d regime (\xi
\~ exp[2\pi\rho_{s}/T], where 2\pi\rho_{s} = 290 +/- 30 K is the effective spin
stiffness). This is the first experimental verification of the renormalized
classical behavior of the anisotropic non-linear sigma model in 2d, which has
been recently proposed for the striped phase in high T_{c} cuprates.Comment: 4 pages, 3 figure
Critical dynamics of a spin-5/2 2D isotropic antiferromagnet
We report a neutron scattering study of the dynamic spin correlations in
RbMnF, a two-dimensional spin-5/2 antiferromagnet. By tuning an
external magnetic field to the value for the spin-flop line, we reduce the
effective spin anisotropy to essentially zero, thereby obtaining a nearly ideal
two-dimensional isotropic antiferromagnet. From the shape of the quasielastic
peak as a function of temperature, we demonstrate dynamic scaling for this
system and find a value for the dynamical exponent . We compare these
results to theoretical predictions for the dynamic behavior of the
two-dimensional Heisenberg model, in which deviations from provide a
measure of the corrections to scaling.Comment: 5 pages, 4 figures. Submitted to Physical Review B, Rapid
Communication
Evidence for Ballistic Thermal Conduction in the One-Dimensional S=1/2 Heisenberg Antiferromagnetic Spin System Sr2CuO3
We have measured the thermal conductivity of the one-dimensional (1D) S=1/2
Heisenberg antiferromagnetic spin system of Sr2Cu1-xPdxO3 single crystals
including nonmagnetic impurities of Pd2+. It has been found that the mean free
path of spinons along the 1D spin chain at low temperatures is very close to
the average length of finite spin chains between spin defects estimated from
the magnetic susceptibility measurements. This proves that the thermal
conduction due to spinons at low temperatures in Sr2CuO3 is ballistic as
theoretically expected [Zotos et al.: Phys. Rev. Lett. 55 (1997) 11029]
Ferromagnetism in annealed ce0-95Co0-05O2 and Ce0-95Ni0-05O2 nanoparticles
This paper reports an investigation on the role of transition-metal ions in producing ferromagnetism in CeO2 nanoparticles by electron paramagnetic resonancePR). Several samples of CeO2 nanoparticles annealed at 200, 300, 400, and 500C, doped with 5% Ni and 5% Co ions, characterized by X-ray diffractionRD), X-ray photoelectron spectroscopyPS), thermogravimetry analysisGA) and mass spectroscopyS), were investigated by X-band EPR at 4, 10 and 300 K, and by magnetometry at 300 K. Magnetic properties and EPR/FMRerromagnetic Resonance) spectra of these nanoparticle samples were found to depend strongly on the annealing temperatureA), oxygen stoichiometry, and dopant-ion species. Different behavior of saturation magnetization in the samples with the dopants, Co and Ni, is found to be due to different-inward and outward-surface diffusion of these impurity ions, respectively, during annealing. A detailed simulation of EPR/FMR spectra of isolated Co and Ni ions carried out here provides in-depth details on the role of the doped ions and oxygen? defects played in the observed magnetic properties. Copyright © 2013 American Scientific Publishers All rights reserved
How linear features alter predator movement and the functional response
In areas of oil and gas exploration, seismic lines have been reported to alter the movement patterns of wolves (Canis lupus). We developed a mechanistic first passage time model, based on an anisotropic elliptic partial differential equation, and used this to explore how wolf movement responses to seismic lines influence the encounter rate of the wolves with their prey. The model was parametrized using 5 min GPS location data. These data showed that wolves travelled faster on seismic lines and had a higher probability of staying on a seismic line once they were on it. We simulated wolf movement on a range of seismic line densities and drew implications for the rate of predator–prey interactions as described by the functional response. The functional response exhibited a more than linear increase with respect to prey density (type III) as well as interactions with seismic line density. Encounter rates were significantly higher in landscapes with high seismic line density and were most pronounced at low prey densities. This suggests that prey at low population densities are at higher risk in environments with a high seismic line density unless they learn to avoid them
Direct inversion of S-P differential arrival-times for Vp/Vs ratio in SE Asia
Open Access via Jisc Wiley agreementPeer reviewedPublisher PD
Conductivity of quantum-spin chains: A Quantum Monte Carlo approach
We discuss zero-frequency transport properties of various spin-1/2 chains. We
show, that a careful analysis of Quantum Monte-Carlo (QMC) data on the
imaginary axis allows to distinguish between intrinsic ballistic and diffusive
transport. We determine the Drude weight, current-relaxation life-time and the
mean-free path for integrable and a non-integrable quantum-spin chain. We
discuss, in addition, some phenomenological relations between various
transport-coefficients and thermal response functions
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