10,879 research outputs found
Berry phase and quantum criticality in Yang--Baxter systems
Spin interaction Hamiltonians are obtained from the unitary Yang--Baxter
-matrix. Based on which, we study Berry phase and quantum
criticality in the Yang--Baxter systems.Comment: 7 pages, no figures. Accepted for publication in Annals of Physic
X-ray scaling relations from a complete sample of the richest maxBCG clusters
We use a complete sample of 38 richest maxBCG clusters to study the
ICM-galaxy scaling relations and the halo mass selection properties of the
maxBCG algorithm, based on X-ray and optical observations. The clusters are
selected from the two largest bins of optical richness in the Planck stacking
work with the maxBCG richness . We analyze their Chandra and
XMM-Newton data to derive the X-ray properties of the ICM. We then use the
distribution of , , to study the mass selection
of maxBCG. Compared with previous works based on the whole richness
sample, a significant fraction of blended systems with boosted richness is
skewed into this richest sample. Parts of the blended halos are picked apart by
the redMaPPer, an updated red-sequence cluster finding algorithm with lower
mass scatter. Moreover, all the optical blended halos are resolved as
individual X-ray halos, following the established and
relations. We further discuss that the discrepancy between ICM-galaxy scaling
relations, especially for future blind stacking, can come from several factors,
including miscentering, projection, contamination of low mass systems, mass
bias and covariance bias. We also evaluate the fractions of relaxed and cool
core clusters in our sample. Both are smaller than those from SZ or X-ray
selected samples. Moreover, disturbed clusters show a higher level of mass bias
than relaxed clusters.Comment: 28 pages, 12 figures, MNRAS in pres
Managing Forests and Water for People under a Changing Environment
The Earth has entered the Anthropocene epoch and forest managers are facing unprecedented challenges to meet multiple ecosystem service demands from forests. Understanding the complex forest-water relations under a changing environment must add a human dimension, and this is essential in the move towards sustainable forest management in the 21st century. This Special Issue contains 10 papers presented at a joint international forest and water conference in Chile in 2018. These studies provide global examples on new advancements in sciences in forest ecohydrology, watershed management, and ecosystem service assessment under various geographical and socioeconomic settings
Activity and social interactions in a wideranging specialist scavenger, the Tasmanian devil (Sarcophilus harrisii), revealed by animalborne video collars
Observing animals directly in the field provides the most accurate understanding of animal behaviour and resource selection. However, making prolonged observation of undisturbed animals is difficult or impossible for many species. To overcome this problem for the Tasmanian devil (Sarcophilus harrisii), a cryptic and nocturnal carnivore, we developed animal-borne video collars to investigate activity patterns, foraging behaviour and social interactions. We collected 173 hours of footage from 13 individual devils between 2013 and 2017. Devils were active mostly at night, and resting was the most common behaviour in all diel periods. Devils spent more time scavenging than hunting and exhibited opportunistic and flexible foraging behaviours. Scavenging occurred mostly in natural vegetation but also in anthropogenic vegetation and linear features (roads and fence lines). Scavenging frequency was inversely incremental with size e.g. small carcasses were scavenged most frequently. Agonistic interactions with conspecifics occurred most often when devils were traveling but also occurred over carcasses or dens. Interactions generally involved vocalisations and brief chases without physical contact. Our results highlight the importance of devils as a scavenger in the Tasmanian ecosystem, not just of large carcasses for which devils are well known but in cleaning up small items of carrion in the bush. Our results also show the complex nature of intraspecific interactions, revealing greater detail on the context in which interactions occur. In addition, this study demonstrates the benefits of using animal-borne imaging in quantifying behaviour of elusive, nocturnal carnivores not previously seen using conventional field methods
New R-matrices from Representations of Braid-Monoid Algebras based on Superalgebras
In this paper we discuss representations of the Birman-Wenzl-Murakami algebra
as well as of its dilute extension containing several free parameters. These
representations are based on superalgebras and their baxterizations permit us
to derive novel trigonometric solutions of the graded Yang-Baxter equation. In
this way we obtain the multiparametric -matrices associated to the
, and
quantum symmetries. Two other families of multiparametric -matrices not
predicted before within the context of quantum superalgebras are also
presented. The latter systems are indeed non-trivial generalizations of the
vertex model when both distinct edge variables statistics
and extra free-parameters are admissible.Comment: 26 page
Reaction-Diffusion Processes as Physical Realizations of Hecke Algebras
We show that the master equation governing the dynamics of simple diffusion
and certain chemical reaction processes in one dimension give time evolution
operators (Hamiltonians) which are realizations of Hecke algebras. In the case
of simple diffusion one obtains, after similarity transformations, reducible
hermitian representations while in the other cases they are non-hermitian and
correspond to supersymmetric quotients of Hecke algebras.Comment: Latex, 6 pages, BONN-HE-93.1
On Integrable Quantum Group Invariant Antiferromagnets
A new open spin chain hamiltonian is introduced. It is both integrable
(Sklyanin`s type matrices are used to achieve this) and invariant under
transformations in nilpotent irreps for
. Some considerations on the centralizer of nilpotent
representations and its representation theory are also presented.Comment: IFF-5/92, 13 pages, LaTex file, 8 figures available from author
Optimal client recommendation for market makers in illiquid financial products
The process of liquidity provision in financial markets can result in
prolonged exposure to illiquid instruments for market makers. In this case,
where a proprietary position is not desired, pro-actively targeting the right
client who is likely to be interested can be an effective means to offset this
position, rather than relying on commensurate interest arising through natural
demand. In this paper, we consider the inference of a client profile for the
purpose of corporate bond recommendation, based on typical recorded information
available to the market maker. Given a historical record of corporate bond
transactions and bond meta-data, we use a topic-modelling analogy to develop a
probabilistic technique for compiling a curated list of client recommendations
for a particular bond that needs to be traded, ranked by probability of
interest. We show that a model based on Latent Dirichlet Allocation offers
promising performance to deliver relevant recommendations for sales traders.Comment: 12 pages, 3 figures, 1 tabl
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