2,566 research outputs found
Clean Air, Clean Processes? The Struggle over Air Pollution Law in the People\u27s Republic of China
This Article commences in Part I by introducing law-making in China before reconstructing the drafting process and attendant political battles leading up to the revision of China\u27s principal air pollution law in 1995 – which, as Ackerman and Hassler observed with reference to the United States, can be every bit as messy as the soiled air such efforts are intended to address. Part II then examines the institutional factors that ultimately are critical to an understanding of why the 1995 APPCL, as promulgated, fell well short of its original authors\u27 objectives but set in motion a process that over time has led to the realization of at least some of these legislative goals through the 2000 APPCL. The Article concludes by suggesting the implications of these institutional considerations for environmental law and legislative development more generally in the PRC
Bulk viscosity in the nonlinear and anharmonic regime of strange quark matter
The bulk viscosity of cold, dense three-flavor quark matter is studied as a
function of temperature and the amplitude of density oscillations. The study is
also extended to the case of two different types of anharmonic oscillations of
density. We point several qualitative effects due to the anharmonicity,
although quantitatively they appear to be relatively small. We also find that,
in most regions of the parameter space, with the exception of the case of a
very large amplitude of density oscillations (i.e. 10% and above), nonlinear
effects and anharmonicity have a small effect on the interplay of the
nonleptonic and semileptonic processes in the bulk viscosity.Comment: 14 pages, 6 figures; v2: Appendix B is omitted, a few new discussions
added and some new references adde
Vortices on Higher Genus Surfaces
We consider the topological interactions of vortices on general surfaces. If
the genus of the surface is greater than zero, the handles can carry magnetic
flux. The classical state of the vortices and the handles can be described by a
mapping from the fundamental group to the unbroken gauge group. The allowed
configurations must satisfy a relation induced by the fundamental group. Upon
quantization, the handles can carry ``Cheshire charge.'' The motion of the
vortices can be described by the braid group of the surface. How the motion of
the vortices affects the state is analyzed in detail.Comment: 28 pages with 10 figures; uses phyzzx and psfig; Caltech preprint
CALT-68-187
Open Space – a collaborative process for facilitating Tourism IT partnerships
The success of IT projects depends on the success of the partnerships on which they are based. However past research by the author has identified a significant rate of failure in these partnerships, predominantly due to an overly technical mindset, leading to the question: “how do we ensure that, as technological solutions are implemented within tourism, due consideration is given to human-centred issues?” The tourism partnership literature is explored for additional insights revealing that issues connected with power, participation and normative positions play a major role. The method, Open Space, is investigated for its ability to engage stakeholders in free and open debate. This paper reports on a one-day Open Space event sponsored by two major intermediaries in the UK travel industry who wanted to consult their business partners. Both the running of the event and its results reveal how Open Space has the potential to address some of the weaknesses associated with tourism partnerships
Comments on spin operators and spin-polarization states of 2+1 fermions
In this brief article we discuss spin polarization operators and spin
polarization states of 2+1 massive Dirac fermions and find a convenient
representation by the help of 4-spinors for their description. We stress that
in particular the use of such a representation allows us to introduce the
conserved covariant spin operator in the 2+1 field theory. Another advantage of
this representation is related to the pseudoclassical limit of the theory.
Indeed, quantization of the pseudoclassical model of a spinning particle in 2+1
dimensions leads to the 4-spinor representation as the adequate realization of
the operator algebra, where the corresponding operator of a first-class
constraint, which cannot be gauged out by imposing the gauge condition, is just
the covariant operator previously introduced in the quantum theory.Comment: 6 page
Anisotropic admixture in color-superconducting quark matter
The analysis of color-superconducting two-flavor deconfined quark matter at
moderate densities is extended to include a particular spin-1 Cooper pairing of
those quarks which do not participate in the standard spin-0 diquark
condensate. (i) The relativistic spin-1 gap Delta' implies spontaneous
breakdown of rotation invariance manifested in the form of the quasi-fermion
dispersion law. (ii) The critical temperature of the anisotropic component is
approximately given by the relation T_c'~ Delta'(T=0)/3. (iii) For massless
fermions the gas of anisotropic Bogolyubov-Valatin quasiquarks becomes
effectively gapless and two-dimensional. Consequently, its specific heat
depends quadratically on temperature. (iv) All collective Nambu-Goldstone
excitations of the anisotropic phase have a linear dispersion law and the whole
system remains a superfluid. (v) The system exhibits an electromagnetic
Meissner effect.Comment: v2: references added, angular dependence of the gap clarified, v3:
extended discussion, typo in eq. (5) corrected, version accepted for
publication in PR
Paramagnetic Meissner Effect and Finite Spin Susceptibility in an Asymmetric Superconductor
A general analysis of Meissner effect and spin susceptibility of a uniform
superconductor in an asymmetric two-component fermion system is presented in
nonrelativistic field theory approach. We found that, the pairing mechanism
dominates the magnetization property of superconductivity, and the asymmetry
enhances the paramagnetism of the system. At the turning point from BCS to
breached pairing superconductivity, the Meissner mass squared and spin
susceptibility are divergent at zero temperature. In the breached pairing state
induced by chemical potential difference and mass difference between the two
kinds of fermions, the system goes from paramagnetism to diamagnetism, when the
mass ratio of the two species increases.Comment: 17pages, 2 figures, published in Physical Review
Bulk viscosity in kaon-condensed color-flavor locked quark matter
Color-flavor locked (CFL) quark matter at high densities is a color
superconductor, which spontaneously breaks baryon number and chiral symmetry.
Its low-energy thermodynamic and transport properties are therefore dominated
by the H (superfluid) boson, and the octet of pseudoscalar pseudo-Goldstone
bosons of which the neutral kaon is the lightest. We study the CFL-K^0 phase,
in which the stress induced by the strange quark mass causes the kaons to
condense, and there is an additional ultra-light "K^0" Goldstone boson arising
from the spontaneous breaking of isospin. We compute the bulk viscosity of
matter in the CFL-K^0 phase, which arises from the beta-equilibration processes
K^0H+H and K^0+HH. We find that the bulk viscosity varies as T^7, unlike
the CFL phase where it is exponentially Boltzmann-suppressed by the kaon's
energy gap. However, in the temperature range of relevance for r-mode damping
in compact stars, the bulk viscosity in the CFL-K^0 phase turns out to be even
smaller than in the uncondensed CFL phase, which already has a bulk viscosity
much smaller than all other known color-superconducting quark phases.Comment: 23 pages, 8 figures, v2: references added; minor rephrasings in the
conclusions; version to appear in J. Phys.
Bulk viscosity in a cold CFL superfluid
We compute one of the bulk viscosity coefficients of cold CFL quark matter in
the temperature regime where the contribution of mesons, quarks and gluons to
transport phenomena is Boltzmann suppressed. In that regime dissipation occurs
due to collisions of superfluid phonons, the Goldstone modes associated to the
spontaneous breaking of baryon symmetry. We first review the hydrodynamics of
relativistic superfluids, and remind that there are at least three bulk
viscosity coefficients in these systems. We then compute the bulk viscosity
coefficient associated to the normal fluid component of the superfluid. In our
analysis we use Son's effective field theory for the superfluid phonon, amended
to include scale breaking effects proportional to the square of the strange
quark mass m_s. We compute the bulk viscosity at leading order in the scale
breaking parameter, and find that it is dominated by collinear splitting and
joining processes. The resulting transport coefficient is zeta=0.011 m_s^4/T,
growing at low temperature T until the phonon fluid description stops making
sense. Our results are relevant to study the rotational properties of a compact
star formed by CFL quark matter.Comment: 19 pages, 2 figures; one reference added, version to be published in
JCA
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