170,349 research outputs found
Race riots on the beach: A case for criminalising hate speech?
noThis paper analyses the verbal and textual hostility employed by rioters, politicians and the media in Sydney (Australia) in December 2005 in the battle over Sutherland Shire¿s Cronulla Beach. By better understanding the linguistic conventions underlying all forms of maledictive hate, we are better able to address the false antimonies between free speech and the regulation of speech. It is also argued that understanding the harms of hate speech provides us with the tools necessary to create a more responsive framework for criminalising some forms of hate speech as a preliminary process in reducing or eliminating hate violence
Local physics of magnetization plateaux in the Shastry-Sutherland model
We address the physical mechanism responsible for the emergence of
magnetization plateaux in the Shastry-Sutherland model. By using a hierarchical
mean-field approach we demonstrate that a plateau is stabilized in a certain
{\it spin pattern}, satisfying {\it local} commensurability conditions derived
from our formalism. Our results provide evidence in favor of a robust local
physics nature of the plateaux states, and are in agreement with recent NMR
experiments on \scbo.Comment: 4 pages, LaTeX 2
Integrable Spin Chain with Reflecting End
A new integrable spin chain of the Haldane-Shastry type is introduced. It is
interpreted as the inverse-square interacting spin chain with a {\it reflecting
end}. The lattice points of this model consist of the square roots of the zeros
of the Laguerre polynomial. Using the ``exchange operator formalism'', the
integrals of motion for the model are explicitly constructed.Comment: 13 pages, REVTeX3, with minor correction
Jet-Induced Emission-Line Nebulosity and Star Formation in the High-Redshift Radio Galaxy 4C41.17
The high redshift radio galaxy 4C41.17 consists of a powerful radio source in
which previous work has shown that there is strong evidence for jet-induced
star formation along the radio axis. We argue that nuclear photoionization is
not responsible for the excitation of the emission line clouds and we construct
a jet-cloud interaction model to explain the major features revealed by the
data. The interaction of a high-powered jet with a dense cloud in the halo of
4C41.17 produces shock-excited emission-line nebulosity through ~1000 km/s
shocks and induces star formation. The CIII to CIV line ratio and the CIV
luminosity emanating from the shock, imply that the pre-shock density in the
line-emitting cloud is high enough (~1-10 cm^-3) that shock initiated star
formation could proceed on a timescale of order a few x 10^6 yrs, well within
the estimated dynamical age of the radio source. Broad (FWHM ~ 100 - 1400 km/s)
emission lines are attributed to the disturbance of the gas cloud by a partial
bow--shock and narrow emission lines (FWHM ~ 500 - 650 km/s) (in particular
CIV) arise in precursor emission in relatively low metallicity gas. The implied
baryonic mass ~ 8 \times 10^{10} solar masses of the cloud is high and implies
that Milky Way size condensations existed in the environments of forming radio
galaxies at a redshift of 3.8. Our interpretation of the data provides a
physical basis for the alignment of the radio, emission-line and UV continuum
images in some of the highest redshift radio galaxies and the analysis
presented here may form a basis for the calculation of densities and cloud
masses in other high redshift radio galaxies.Comment: 18 pages, 5 figures; uses astrobib.sty and aaspp4.sty. Better
versions of figures available via anonymous from
ftp://mso.anu.edu.au:pub/pub/geoff/4C41.1
Recommended from our members
Effective engagement of conservation scientists with decision-makers
This chapter offers advice on how the conservation science community can effectively engage with decision-makers. The rationales for why we, as scientists, need to do this have been widely discussed in the literature. Often, the reasons offered are normative, pragmatic, or instrumental (de Vente, 2016); in other words, there is a belief that engaging with decision-makers leads to better informed, more acceptable decisions. Indeed, better engagement may lead to the greater uptake of evidence for conservation decisions, something which some scholars argue is a priority for effective management (e.g. Gardner et al., 2018; Sutherland and Wordley, 2017)
Family of exactly solvable models with an ultimative quantum paramagnetic ground state
We present a family of two-dimensional frustrated quantum magnets solely
based on pure nearest-neighbor Heisenberg interactions which can be solved
quasi-exactly. All lattices are constructed in terms of frustrated quantum
cages containing a chiral degree of freedom protected by frustration. The
ground states of these models are dubbed ultimate quantum paramagnets and
exhibit an extensive entropy at zero temperature. We discuss the unusual and
extensively degenerate excitations in such phases. Implications for
thermodynamic properties as well as for decoherence free quantum computation
are discussed
Unconventional magnetization plateaus in a Shastry-Sutherland spin tube
Using density matrix renormalization group (DMRG) and perturbative continuous
unitary transformations (PCUTs), we study the magnetization process in a
magnetic field for all coupling strengths of a quasi-1D version of the 2D
Shastry-Sutherland lattice, a frustrated spin tube made of two orthogonal dimer
chains. At small inter-dimer coupling, plateaus in the magnetization appear at
1/6, 1/4, 1/3, 3/8, and 1/2. As in 2D, they correspond to a Wigner crystal of
triplons. However, close to the boundary of the product singlet phase, plateaus
of a new type appear at 1/5 and 3/4. They are stabilized by the localization of
{\it bound states} of triplons. Their magnetization profile differs
significantly from that of single triplon plateaus and leads to specific NMR
signatures. We address the possibility to stabilize such plateaus in further
geometries by analyzing small finite clusters using exact diagonalizations and
the PCUTs.Comment: Final version as published in EP
Source identities and kernel functions for deformed (quantum) Ruijsenaars models
We consider the relativistic generalization of the quantum
Calogero-Sutherland models due to Ruijsenaars, comprising the rational,
hyperbolic, trigonometric and elliptic cases. For each of these cases, we find
an exact common eigenfunction for a generalization of Ruijsenaars analytic
difference operators that gives, as special cases, many different kernel
functions; in particular, we find kernel functions for Chalykh-
Feigin-Veselov-Sergeev-type deformations of such difference operators which
generalize known kernel functions for the Ruijsenaars models. We also discuss
possible applications of our results.Comment: 24 page
The perturbation of the quantum Calogero-Moser-Sutherland system and related results
The Hamiltonian of the trigonometric Calogero-Sutherland model coincides with
some limit of the Hamiltonian of the elliptic Calogero-Moser model. In other
words the elliptic Hamiltonian is a perturbed operator of the trigonometric
one. In this article we show the essential self-adjointness of the Hamiltonian
of the elliptic Calogero-Moser model and the regularity (convergence) of the
perturbation for the arbitrary root system. We also show the holomorphy of the
joint eigenfunctions of the commuting Hamiltonians w.r.t the variables (x_1,
>..., x_N) for the A_{N-1}-case. As a result, the algebraic calculation of the
perturbation is justified.Comment: Revised version, 35 page
Calogero-Sutherland Particles as Quasisemions
The ultraviolet structure of the Calogero-Sutherland models is examined, and,
in particular, semions result to have special properties. An analogy with
ultraviolet structures known in anyon quantum mechanics is drawn, and it is
used to suggest possible physical consequences of the observed semionic
properties.Comment: 7 pages, LaTe
- …
