2,520 research outputs found
Quantum Hall induced currents and the magnetoresistance of a quantum point contact
We report an investigation of quantum Hall induced currents by simultaneous
measurements of their magnetic moment and their effect on the conductance of a
quantum point contact (QPC). Features in the magnetic moment and QPC resistance
are correlated at Landau-level filling factors nu=1, 2 and 4, which
demonstrates the common origin of the effects. Temperature and non-linear sweep
rate dependences are observed to be similar for the two effects. Furthermore,
features in the noise of the induced currents, caused by breakdown of the
quantum Hall effect, are observed to have clear correlations between the two
measurements. In contrast, there is a distinct difference in the way that the
induced currents decay with time when the sweeping field halts at integer
filling factor. We attribute this difference to the fact that, while both
effects are sensitive to the magnitude of the induced current, the QPC
resistance is also sensitive to the proximity of the current to the QPC
split-gate. Although it is clearly demonstrated that induced currents affect
the electrostatics of a QPC, the reverse effect, the QPC influencing the
induced current, was not observed
Comparing verbal media for alarm handling: Speech versus textual displays
The rise of computers in command and control domains has meant that control operations can be performed via desk-based visual display terminals. This trend has also produced the potential to display information to operators in a variety of formats. Of particular interest has been the use of text-based displays for alarm presentation. There are possible limitations to the use of text for alarm presentation, not least of which is the need for a dedicated alarms display screen (or, at least, a display page). Given the capability of computers to synthesize speech, it is possible that speech-based alarms could generate the same information as text-based displays without the need for dedicated screen space. In this paper an experimental comparison of speech-based and text-based displays for presentation of alarms is reported. The findings show that speech leads to longer response times than text displays, but that it has minimal effect on the efficacy of fault handling. The results are discussed within the alarm initiated activities framework and implications for alarm system design are outlined
Connection to... Addressing Digital Inequities in Supporting the Well-Being of Young Indigenous Australians in the Wake of COVID-19
(1) Background: This article examines whether connection to digital technologies helps connect young Indigenous people in Australia to culture, community and country to support good mental health and well-being and protect against indirect and potentially long-term effects of COVID-19. (2) Method: We reviewed literature published between February and November 2020 and policy responses related to digital strategies. We searched PubMed, Google Scholar, government policy websites and key Indigenous literature sources, identifying 3460 articles. Of these, 30 articles and 26 policy documents were included and analysed to identify existing and expected mental health outcomes among Indigenous young people associated with COVID-19 and more broadly. (3) Results: There are inequities in affordable access to digital technologies. Only 63% of Indigenous people have access to internet at home. Digital technologies and social media contribute to strong cultural identity, enhance connections to community and country and improve mental health and social and emotional well-being outcomes. (4) Discussion: Access to digital technologies can facilitate healing and cultural continuity, self-determination and empowerment for young people to thrive, not just survive, in the future. (5) Conclusion: More targeted policies and funding is urgently needed to promote digital technologies to enhance Indigenous young people's access to mental health and well-being services, maintain cultural connections and evaluate the effectiveness of these initiatives using Indigenous well-being indicators
Search strategies for supermassive stars in young clusters and application to nearby galaxies
Supermassive stars (SMS) with masses , formed
by runaway collisions in young, massive, and dense star clusters have been
invoked as a possible solution to the puzzles raised by the presence of
multiple stellar populations and peculiar abundance patterns observed in
globular clusters. However, such objects have not been observed so far. We
developed observational strategies to search for SMS hosted within young
massive clusters (thought to be the precursors of globular clusters, GCs),
which could be applicable in a relatively general fashion, using both
photometric and spectroscopic observations. We used theoretical predictions of
spectra of SMS and SMS-hosting clusters, together with predictions from
standard simple stellar populations to examine their impact on color-color
diagrams and on individual optical spectral lines (primarily Hydrogen emission
and absorption lines). As a first step, we apply our search strategies to a
sample of young star clusters (YSC) from two nearby galaxies with
multi-band observations from the HST and optical integral-field spectroscopy
obtained with MUSE on the Very Large Telescope. We focus on models for SMS with
large radii (corresponding to K), which predict strong
Balmer breaks, and construct proper color-color diagrams to select the
corresponding SMS-hosting cluster candidates. We show that their
spectrophotometric properties are similar to that of normal clusters with ages
of a few hundred Myr, which would, however, show signs of composite stellar
populations, in particular the presence of nebular lines (H and
others). Examining the photometry, overall SEDs, and the spectra of
clusters with strong Balmer breaks, we have found several objects with peculiar
SEDs, the presence of emission lines, or other peculiar signatures. [abridged]Comment: Accepted for publication in A&A, 15 pages, 12 figures, 2 tables,
(Abstract abridged
Structure and play: rethinking regulation in the higher education sector
This paper explores possible tactics for academics working within a context of increasing regulation and constraint. One suggested tactic is to move outside of a creativity-conformity binary. Rather than understanding creativity and conformity as separable, where one is seen as excluding the other, the authors consider the potential of examining the relationships between them. The theme of 'structure and play' illustrates the argument. In the first part of the paper, using various examples from art and design - fields generally associated with creativity - the authors explore the interrelatedness of creativity and conformity. For example, how might design styles, which are generally understood as creative outcomes, constrain creativity and lead to conformity within the design field? Is fashion producing creativity or conformity? Conversely, the ways in which conformity provides the conditions for creativity are also examined. For example, the conformity imposed by the state on artists in the former communist bloc contributed to a thriving underground arts movement which challenged conformity and state regulation. Continuing the theme of 'structure and play', the authors recount a story from an Australian university which foregrounds the ongoing renegotiation of power relations in the academy. This account illustrates how programmatic government in a university, with its aim of regulating conduct, can contribute to unanticipated outcomes. The authors propose that a Foucauldian view of distributed power is useful for academics operating in a context of increasing regulation, as it brings into view sites where power might begin to be renegotiated
Cortical topography of intracortical inhibition influences the speed of decision making
The neocortex contains orderly topographic maps; however, their functional role remains controversial. Theoretical studies have suggested a role in minimizing computational costs, whereas empirical studies have focused on spatial localization. Using a tactile multiple-choice reaction time (RT) task before and after the induction of perceptual learning through repetitive sensory stimulation, we extend the framework of cortical topographies by demonstrating that the topographic arrangement of intracortical inhibition contributes to the speed of human perceptual decision-making processes. RTs differ among fingers, displaying an inverted U-shaped function. Simulations using neural fields show the inverted U-shaped RT distribution as an emergent consequence of lateral inhibition. Weakening inhibition through learning shortens RTs, which is modeled through topographically reorganized inhibition. Whereas changes in decision making are often regarded as an outcome of higher cortical areas, our data show that the spatial layout of interaction processes within representational maps contributes to selection and decision-making processes
Indigenous Resilience in Australia: A Scoping Review Using a Reflective Decolonizing Collective Dialogue
Contemporary definitions and understandings of resilience refer to an individual's positive adaptation to the experience of adversity. One of the challenges of this extant body of work is that the central concept of resilience is rarely questioned. Current understandings of these concepts, largely framed in Western understandings, are unquestioningly accepted, reframed for, yet not by, Indigenous peoples, and then are unchallenged when imposed on Indigenous peoples. A scoping review was conducted and reported in line with the PRISMA-ScR guidelines. The review involved the participation of local Aboriginal Research Cultural Advisory Groups who participated and approved the analysis of the findings and collaborated on the design and writing of the paper. Eight publications drew on Aboriginal constructs of resilience in examining the effectiveness of programs, processes, and practices to promote individual and/or collective resilience and well-being. Most studies emphasized the need for strategies to strengthen individual or community connection to culture to foster resilience. Six studies used culturally validated strength-based tools to measure resilience, while two relied on Western constructs. This review reveals both the distinctive colonial characteristics of adversity experienced by Aboriginal people and the range of coping strategies and protective resources that support the development of resilience within different Aboriginal communities in diverse research sites across Australia. Importantly, many studies confirm adversity is linked to the enduring legacies of colonization, continuous and cumulative transgenerational grief and loss, structural inequities, racism, and discrimination. These external factors of adversity are unique to Aboriginal populations, as are the protective factors that entail strengthening connection to culture (including language reclamation), community, ancestry and land (including management and economic development) which contribute to individual and collective resilience. These findings suggest that Aboriginal community resilience is strengthened through the collective experience of adversity, such as transgenerational grief and loss, and the resulting support structures and shared resources that are developed and maintained through cultural practices to strengthen the bonds and mutual reciprocity to participate in transformative strategies to address adversity. This review highlights that strategies such as building on community strengths, capacities, and resources is critical when strengthening resilience within Indigenous communities across Australia
Simple model for 1/f noise
We present a simple stochastic mechanism which generates pulse trains
exhibiting a power law distribution of the pulse intervals and a
power spectrum over several decades at low frequencies with close to
one. The essential ingredient of our model is a fluctuating threshold which
performs a Brownian motion. Whenever an increasing potential hits the
threshold, is reset to the origin and a pulse is emitted. We show that
if increases linearly in time, the pulse intervals can be approximated
by a random walk with multiplicative noise. Our model agrees with recent
experiments in neurobiology and explains the high interpulse interval
variability and the occurrence of noise observed in cortical
neurons and earthquake data.Comment: 4 pages, 4 figure
Heat Capacity Evidence for the Suppression of Skyrmions at Large Zeeman Energy
Measurements on a multilayer two-dimensional electron system (2DES) near
Landau level filling =1 reveal the disappearance of the nuclear spin
contribution to the heat capacity as the ratio between the Zeeman
and Coulomb energies exceeds a critical value 0.04. This
disappearance suggests the vanishing of the Skyrmion-mediated coupling between
the lattice and the nuclear spins as the spin excitations of the 2DES make a
transition from Skyrmions to single spin-flips above . Our
experimental is smaller than the calculated =0.054
for an ideal 2DES; we discuss possible origins of this discrepancy.Comment: Experimental paper, 6 figure
Critical and Near-Critical Branching Processes
Scale-free dynamics in physical and biological systems can arise from a
variety of causes. Here, we explore a branching process which leads to such
dynamics. We find conditions for the appearance of power laws and study
quantitatively what happens to these power laws when such conditions are
violated. From a branching process model, we predict the behavior of two
systems which seem to exhibit near scale-free behavior--rank-frequency
distributions of number of subtaxa in biology, and abundance distributions of
genotypes in an artificial life system. In the light of these, we discuss
distributions of avalanche sizes in the Bak-Tang-Wiesenfeld sandpile model.Comment: 9 pages LaTex with 10 PS figures. v.1 of this paper contains results
from non-critical sandpile simulations that were excised from the published
versio
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