2,601 research outputs found
Devolution as process: institutional structures, state personnel and transport policy in the United Kingdom
Devolution has been described as a key ‘global trend’ over recent decades as governments have decentralised power and responsibilities to subordinate regional institutions (Rodriguez-Pose and Gill, 2003). UK devolution is characterised by its asymmetrical nature with different territories granted different institutional arrangements and powers. In this paper, we seek examine the role of state personnel in mobilising the new institutional machinery and managing the process of devolution, focusing on transport policy. Our research shows a clear contrast between London and Northern Ireland, on the one hand, and Scotland and Wales, on the other, in terms of the effectiveness of political leaders in creating clear policy priorities and momentum in transport
Comparative Analysis of Non-thermal Emissions and Study of Electron Transport in a Solar Flare
We study the non-thermal emissions in a solar flare occurring on 2003 May 29
by using RHESSI hard X-ray (HXR) and Nobeyama microwave observations. This
flare shows several typical behaviors of the HXR and microwave emissions: time
delay of microwave peaks relative to HXR peaks, loop-top microwave and
footpoint HXR sources, and a harder electron energy distribution inferred from
the microwave spectrum than from the HXR spectrum. In addition, we found that
the time profile of the spectral index of the higher-energy (\gsim 100 keV)
HXRs is similar to that of the microwaves, and is delayed from that of the
lower-energy (\lsim 100 keV) HXRs. We interpret these observations in terms
of an electron transport model called {\TPP}. We numerically solved the
spatially-homogeneous {\FP} equation to determine electron evolution in energy
and pitch-angle space. By comparing the behaviors of the HXR and microwave
emissions predicted by the model with the observations, we discuss the
pitch-angle distribution of the electrons injected into the flare site. We
found that the observed spectral variations can qualitatively be explained if
the injected electrons have a pitch-angle distribution concentrated
perpendicular to the magnetic field lines rather than isotropic distribution.Comment: 32 pages, 12 figures, accepted for publication in The Astronomical
Journa
Metal-insulator transition in three dimensional Anderson model: universal scaling of higher Lyapunov exponents
Numerical studies of the Anderson transition are based on the finite-size
scaling analysis of the smallest positive Lyapunov exponent. We prove
numerically that the same scaling holds also for higher Lyapunov exponents.
This scaling supports the hypothesis of the one-parameter scaling of the
conductance distribution. From the collected numerical data for quasi one
dimensional systems up to the system size 24 x 24 x infinity we found the
critical disorder 16.50 < Wc < 16.53 and the critical exponent 1.50 < \nu <
1.54. Finite-size effects and the role of irrelevant scaling parameters are
discussed.Comment: 4 pages, 2 figure
Particle formation and interaction
A wide variety of experiments can be conducted on the Space Station that involve the physics of small particles of planetary significance. Processes of interest include nucleation and condensation of particles from a gas, aggregation of small particles into larger ones, and low velocity collisions of particles. All of these processes could be investigated with a general purpose facility on the Space Station. The microgravity environment would be necessary to perform many experiments, as they generally require that particles be suspended for periods substantially longer than are practical at 1 g. Only experiments relevant to planetary processes will be discussed in detail here, but it is important to stress that a particle facility will be useful to a wide variety of scientific disciplines, and can be used to address many scientific problems
Increased L-ornithine production by an arg mutant of Acinetobacter lwoffi
The metabolic production of L-ornithine by an arg mutant of Acinetobacter Iwoffi using n-hexadecane as sole carbon source was studied. Time course experiments under optimised conditions showed that L-ornithine production was growth related, with maximum concentrations (10.5gl-1) accumulating in the late exponential phase of growth
Analytical realization of finite-size scaling for Anderson localization. Does the band of critical states exist for d>2?
An analytical realization is suggested for the finite-size scaling algorithm
based on the consideration of auxiliary quasi-1D systems. Comparison of the
obtained analytical results with the results of numerical calculations
indicates that the Anderson transition point is splitted into the band of
critical states. This conclusion is supported by direct numerical evidence
(Edwards and Thouless, 1972; Last and Thouless, 1974; Schreiber, 1985; 1990).
The possibility of restoring the conventional picture still exists but requires
a radical reinterpretetion of the raw numerical data.Comment: PDF, 11 page
Finite-size scaling from self-consistent theory of localization
Accepting validity of self-consistent theory of localization by Vollhardt and
Woelfle, we derive the finite-size scaling procedure used for studies of the
critical behavior in d-dimensional case and based on the use of auxiliary
quasi-1D systems. The obtained scaling functions for d=2 and d=3 are in good
agreement with numerical results: it signifies the absence of essential
contradictions with the Vollhardt and Woelfle theory on the level of raw data.
The results \nu=1.3-1.6, usually obtained at d=3 for the critical exponent of
the correlation length, are explained by the fact that dependence L+L_0 with
L_0>0 (L is the transversal size of the system) is interpreted as L^{1/\nu}
with \nu>1. For dimensions d\ge 4, the modified scaling relations are derived;
it demonstrates incorrectness of the conventional treatment of data for d=4 and
d=5, but establishes the constructive procedure for such a treatment.
Consequences for other variants of finite-size scaling are discussed.Comment: Latex, 23 pages, figures included; additional Fig.8 is added with
high precision data by Kramer et a
CRITICAL EXPONENTS FOR THE METAL-INSULATOR-TRANSITION
Non-standard .sty file `equations.sty' now included inline. The critical
exponents of the metal--insulator transition in disordered systems have been
the subject of much published work containing often contradictory results.
Values ranging between \half and can be found even in the recent
literature. In this paper the results of a long term study of the transition
are presented. The data have been calculated with sufficient accuracy (0.2\%)
that the calculated exponent can be quoted as with
confidence. The reasons for the previous scatter of results is discussed.Comment: 8 pages + figures, LaTe
Anderson transitions in three-dimensional disordered systems with randomly varying magnetic flux
The Anderson transition in three dimensions in a randomly varying magnetic
flux is investigated in detail by means of the transfer matrix method with high
accuracy. Both, systems with and without an additional random scalar potential
are considered. We find a critical exponent of with random
scalar potential. Without it, is smaller but increases with the system
size and extrapolates within the error bars to a value close to the above. The
present results support the conventional classification of universality classes
due to symmetry.Comment: 4 pages, 2 figures, to appear in Phys. Rev.
The Anderson transition: time reversal symmetry and universality
We report a finite size scaling study of the Anderson transition. Different
scaling functions and different values for the critical exponent have been
found, consistent with the existence of the orthogonal and unitary universality
classes which occur in the field theory description of the transition. The
critical conductance distribution at the Anderson transition has also been
investigated and different distributions for the orthogonal and unitary classes
obtained.Comment: To appear in Physical Review Letters. Latex 4 pages with 4 figure
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