110 research outputs found
Microscopic theory for the light-induced anomalous Hall effect in graphene
We employ a quantum Liouville equation with relaxation to model the recently
observed anomalous Hall effect in graphene irradiated by an ultrafast pulse of
circularly polarized light. In the weak-field regime, we demonstrate that the
Hall effect originates from an asymmetric population of photocarriers in the
Dirac bands. By contrast, in the strong-field regime, the system is driven into
a non-equilibrium steady state that is well-described by topologically
non-trivial Floquet-Bloch bands. Here, the anomalous Hall current originates
from the combination of a population imbalance in these dressed bands together
with a smaller anomalous velocity contribution arising from their Berry
curvature. This robust and general finding enables the simulation of electrical
transport from light-induced Floquet-Bloch bands in an experimentally relevant
parameter regime and creates a pathway to designing ultrafast quantum devices
with Floquet-engineered transport properties
Metastable order protected by destructive many-body interference
The phenomenon of metastability can shape dynamical processes on all temporal
and spatial scales. Here, we induce metastable dynamics by pumping ultracold
bosonic atoms from the lowest band of an optical lattice to an excitation band,
via a sudden quench of the unit cell. The subsequent relaxation process to the
lowest band displays a sequence of stages, which include a metastable stage,
during which the atom loss from the excitation band is strongly suppressed.
Using classical-field simulations and analytical arguments, we provide an
explanation for this experimental observation, in which we show that the
transient condensed state of the atoms in the excitation band is a dark state
with regard to collisional decay and tunneling to a low-energy orbital.
Therefore the metastable state is stabilized by destructive interference due to
the chiral phase pattern of the condensed state. Our experimental and
theoretical study provides a detailed understanding of the different stages of
a paradigmatic example of many-body relaxation dynamics
The Effectiveness of Gambling Exclusion Programs in Queensland
This is the research report for the study The Effectiveness of Gambling Exclusion Programs in Queensland, commissioned by the Queensland Department of Justice and Attorney General under its Responsible Gambling Research Grants Program 2011. The project was undertaken by the Centre for Gambling Education and Research at Southern Cross University in collaboration with the University of New England. The study was conducted over 24 months, commencing in February 2012
Data on the fungal species consumed by mammal species in Australia
The data reported here support the manuscript Nuske et al. (2017). Searches were made for quantitative data on the occurrence of fungi within dietary studies of Australian mammal species. The original location reported in each study was used as the lowest grouping variable within the dataset. To standardise the data and compare dispersal events from populations of different mammal species that might overlap, data from locations were further pooled and averaged across sites if they occurred within 100 km of a random central point. Three locations in Australia contained data on several (>7) mycophagous mammals, all other locations had data on 1–3 mammal species. Within these three locations, the identity of the fungi species was compared between mammal species’ diets. A list of all fungi species found in Australian mammalian diets is also provide along with the original reference and fungal synonym names
Floquet dynamics in light-driven solids
We demonstrate how the properties of light-induced electronic Floquet states
in solids impact natural physical observables, such as transport properties, by
capturing the environmental influence on the electrons. We include the
environment as dissipative processes, such as inter-band decay and dephasing,
often ignored in Floquet predictions. These dissipative processes determine the
Floquet band occupations of the emergent steady state, by balancing out the
optical driving force. In order to benchmark and illustrate our framework for
Floquet physics in a realistic solid, we consider the light-induced Hall
conductivity in graphene recently reported by J.~W.~McIver, et al., Nature
Physics (2020). We show that the Hall conductivity is estimated by the Berry
flux of the occupied states of the light-induced Floquet bands, in addition to
the kinetic contribution given by the average band velocity. Hence, Floquet
theory provides an interpretation of this Hall conductivity as a
geometric-dissipative effect. We demonstrate this mechanism within a master
equation formalism, and obtain good quantitative agreement with the
experimentally measured Hall conductivity, underscoring the validity of this
approach which establishes a broadly applicable framework for the understanding
of ultrafast non-equilibrium dynamics in solids
Soil biotic and abiotic effects on seedling growth exhibit context-dependent interactions: evidence from a multi-country experiment on Pinus contorta invasion
The success of invasive plants is influenced by many interacting factors, but evaluating multiple possible mechanisms of invasion success and elucidating the relative importance of abiotic and biotic drivers is challenging, and therefore rarely achieved.We used live, sterile or inoculated soil from different soil origins (native range and introduced range plantation; and invaded plots spanning three different countries) in a fully factorial design to simultaneously examine the influence of soil origin and soil abiotic and biotic factors on the growth of invasive Pinus contorta.Our results displayed significant context dependency in that certain soil abiotic conditions in the introduced ranges (soil nitrogen, phosphorus or carbon content) influenced responses to inoculation treatments.Our findings do not support the enemy release hypothesis or the enhanced mutualism hypothesis, as biota from native and plantation ranges promoted growth similarly. Instead, our results support the missed mutualism hypothesis, as biota from invasive ranges were the least beneficial for seedling growth. Our study provides a novel perspective on how variation in soil abiotic factors can influence plant-soil feedbacks for an invasive tree across broad biogeographical contexts
Women's gambling behaviour, product preferences, and perceptions of product harm: Differences by age and gambling risk status
Background: Women's participation in, and harm from gambling, is steadily increasing. There has been very limited research to investigate how gambling behaviour, product preferences, and perceptions of gambling harm may vary across subgroups of women. Methods: This study surveyed a convenience sample of 509 women from Victoria and New South Wales, Australia. Women were asked a range of questions about their socio-demographic characteristics and gambling behaviour. Focusing on four gambling products in Australia-casino gambling, electronic gambling machines (EGMs), horse betting, and sports betting-women were asked about their frequency of participation, their product preferences, and perceptions of product harms. The sample was segmented a priori according to age and gambling risk status, and differences between groups were identified using Chi-square tests and ANOVAs. Thematic analysis was used to interpret qualitative data. Results: Almost two thirds (n=324, 63.7%) of women had engaged with one of the four products in the previous 12 months. Compared to other age groups, younger women aged 16-34 years exhibited a higher proportion of problem gambling, gambled more frequently, and across more products. While EGMs were the product gambled on most frequently by women overall, younger women were significantly more likely to bet on sports and gamble at casinos relative to older women. Qualitative data indicated that younger women engaged with gambling products as part of a 'night out', 'with friends', due to their 'ease of access' and perceived 'chance of winning big'. There were significant differences in the perceptions of the harms associated with horse and sports betting according to age and gambling risk status, with younger women and gamblers perceiving these products as less harmful. Conclusions: This study highlights that there are clear differences in the gambling behaviour, product preferences, and perceptions of product harms between subgroups of women. A gendered approach will enable public health researchers and policymakers to ensure that the unique factors associated with women's gambling are taken into consideration in a comprehensive public health approach to reducing and preventing gambling harm
Critical literacy as a pedagogical goal in English language teaching
In this chapter, the authors provide an overview of the area of critical literacy as it pertains to second language pedagogy (curriculum and instruction). After considering the historical origins of critical literacy (from antiquity, and including in first language education), they consider how it began to penetrate the field of applied linguistics. They note the geographical and institutional spread of critical literacy practice as documented by published accounts. They then sketch the main features of L2 critical literacy practice. To do this, they acknowledge how practitioners have reported on their practices regarding classroom content and process. The authors also draw attention to the outcomes of these practices as well as challenges that practitioners have encountered in incorporating critical literacy into their second language classrooms
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