12,893 research outputs found
Comparative Monte Carlo Efficiency by Monte Carlo Analysis
We propose a modified power method for computing the subdominant eigenvalue
of a matrix or continuous operator. Here we focus on defining
simple Monte Carlo methods for its application. The methods presented use
random walkers of mixed signs to represent the subdominant eigenfuction.
Accordingly, the methods must cancel these signs properly in order to sample
this eigenfunction faithfully. We present a simple procedure to solve this sign
problem and then test our Monte Carlo methods by computing the of
various Markov chain transition matrices. We first computed for
several one and two dimensional Ising models, which have a discrete phase
space, and compared the relative efficiencies of the Metropolis and heat-bath
algorithms as a function of temperature and applied magnetic field. Next, we
computed for a model of an interacting gas trapped by a harmonic
potential, which has a mutidimensional continuous phase space, and studied the
efficiency of the Metropolis algorithm as a function of temperature and the
maximum allowable step size . Based on the criterion, we
found for the Ising models that small lattices appear to give an adequate
picture of comparative efficiency and that the heat-bath algorithm is more
efficient than the Metropolis algorithm only at low temperatures where both
algorithms are inefficient. For the harmonic trap problem, we found that the
traditional rule-of-thumb of adjusting so the Metropolis acceptance
rate is around 50% range is often sub-optimal. In general, as a function of
temperature or , for this model displayed trends defining
optimal efficiency that the acceptance ratio does not. The cases studied also
suggested that Monte Carlo simulations for a continuum model are likely more
efficient than those for a discretized version of the model.Comment: 23 pages, 8 figure
âDonât talk about the gay characterâ: Barriers to queer young adult fiction and authors in schools and libraries
© 2018, AATE - Australian Association Teaching English. All rights reserved. This article explores findings from an investigation into the publishing experiences of Australian authors of inclusive Young Adult (YA) fiction. A total of seven authors, each publicly identifying as part of a marginalised community in Australia, were interviewed. This paper concentrates on the findings of semi-structured interviews with two authors of Lesbian, Gay, Bisexual, Transgender, Intersex, Asexual, Pansexual, and Other (LGBTQIAP+) fiction, and their experience of promoting their books in school and library environments. Findings were analysed using Critical Discourse Analysis to understand their interactions with publishers, audiences, and school staff. The research was carried out in 2016 but highlights longstanding issues regarding the inclusion of queer literature for young people in educational spaces, including school libraries and high school English curriculums. More broadly, it contributes to the understanding of how diversity and inclusion within YA Fiction is viewed in Australia, and the role of gatekeepers in providing or denying access
âThe Expectations that We Be Educatorsâ: The view of Australian Authors Young Adult Fiction on their OwnVoices Novels as âWindowsâ for Learning about Marginalized Experiencesâ
This paper discusses empirical research conducted in 2016 with seven Australian authors of OwnVoices young adult fiction who publicly identified as Indigenous Australian, a Person of Colour, or a member of Queer or Disabled communities. Interview data was analyzed using Critical Discourse Analysis to understand authorsâ professional journeys as publicly-identifying marginalized creators within the Australian publishing industry and wider literary community. The study found that all seven authors directly or indirectly invoked the concept of education or learning through their books, with their books functioning as a âwindowâ to readers from communities different to their own, per Bishopâs 1990 metaphor. Five authors positively acknowledged this educational potential, while two did from a negative perspective. This research contributes to our understanding of the additional pressures and expectations placed on authors from marginalized communities, while inserting the voices of Australian authors into broader discussions about equity in childrenâs and young adult fiction
Molecular clouds in the centers of galaxies: Constraints from HCN and CO-13 line emission
We have searched for HCN J=1-0 line emission in the centers of 12 galaxies and have detected it in 10 of them. We have obtained complementary data on J=1-0 and 2-1 transitions of CO-12 and CO-13 in these systems. The ratio of integrated intensities, I(CO 1-0)/I(HCN 1-0) = 25 +/- 11 for this sample. We find that HCN emission of this strength can be produced under conditions of subthermal excitation. In combination with the line ratios in CO and CO-13, HCN puts constraints on the mean conditions of molecular clouds and on the mix of cloud types within the projected beam
Fundamental properties and applications of quasi-local black hole horizons
The traditional description of black holes in terms of event horizons is
inadequate for many physical applications, especially when studying black holes
in non-stationary spacetimes. In these cases, it is often more useful to use
the quasi-local notions of trapped and marginally trapped surfaces, which lead
naturally to the framework of trapping, isolated, and dynamical horizons. This
framework allows us to analyze diverse facets of black holes in a unified
manner and to significantly generalize several results in black hole physics.
It also leads to a number of applications in mathematical general relativity,
numerical relativity, astrophysics, and quantum gravity. In this review, I will
discuss the basic ideas and recent developments in this framework, and
summarize some of its applications with an emphasis on numerical relativity.Comment: 14 pages, 2 figures. Based on a talk presented at the 18th
International Conference on General Relativity and Gravitation, 8-13 July
2007, Sydney, Australi
Monte Carlo Determination of Multiple Extremal Eigenpairs
We present a Monte Carlo algorithm that allows the simultaneous determination
of a few extremal eigenpairs of a very large matrix without the need to compute
the inner product of two vectors or store all the components of any one vector.
The new algorithm, a Monte Carlo implementation of a deterministic one we
recently benchmarked, is an extension of the power method. In the
implementation presented, we used a basic Monte Carlo splitting and termination
method called the comb, incorporated the weight cancellation method of Arnow
{\it et al.}, and exploited a new sampling method, the sewing method, that does
a large state space sampling as a succession of small state space samplings. We
illustrate the effectiveness of the algorithm by its determination of the two
largest eigenvalues of the transfer matrices for variously-sized
two-dimensional, zero field Ising models. While very likely useful for other
transfer matrix problems, the algorithm is however quite general and should
find application to a larger variety of problems requiring a few dominant
eigenvalues of a matrix.Comment: 22 pages, no figure
Evidence for improved urban flood resilience by sustainable drainage retrofit
The rapid growth of cities under modern development pressure has resulted in surface water flooding becoming an increasing hazard and future climate change uncertainties may exacerbate this threat still further: retrofitting sustainable drainage systems to attenuate stormwater runoff has been advocated as part of an integrated solution required to address this problem. Many of these adaptations not only enhance a communityâs resilience to flooding, but may also offer additional benefits in terms of improved environmental amenity and quality of life. The evidence base for sustainable drainage is critically evaluated in respect of the implications for urban planning, as applied to existing housing stocks and business properties in urban areas worldwide. It is concluded that this approach can make a substantial contribution towards urban resilience as part of an integrated approach to managing extreme storms. This will be of interest to urban planners and designers considering the implementation of integrated flood risk management
Quasinormal modes for the charged Vaidya metric
The scalar wave equation is considered in the background of a charged Vaidya
metric in double null coordinates describing a non-stationary charged
black hole with varying mass and charge . The resulting
time-dependent quasinormal modes are presented and analyzed. We show, in
particular, that it is possible to identify some signatures in the quasinormal
frequencies from the creation of a naked singularity.Comment: 4 pages. Prepared for the proceedings of the Spanish Relativity
meeting (ERE2010), Granada, Spain, September 6-10, 201
Scholarly Communication Practices in Humanities and Social Sciences: A Study of Researchersâ Attitudes and Awareness of Open Access
This paper examines issues relating to the perceptions and adoption of open access (OA) and institutional repositories. Using a survey research design, we collected data from academics and other researchers in the humanities, arts and social sciences (HASS) at a university in Australia. We looked at factors influencing choice of publishers and journal outlets, as well as the use of social media and nontraditional channels for scholarly communication. We used an online questionnaire to collect data and used descriptive statistics to analyse the data. Our findings suggest that researchers are highly influenced by traditional measures of quality, such as journal impact factor, and are less concerned with making their work more findable and promoting it through social media. This highlights a disconnect between researchersâ desired outcomes and the efforts that they put in toward the same. Our findings also suggest that institutional policies have the potential to increase OA awareness and adoption. This study contributes to the growing literature on scholarly communication by offering evidence from the HASS field, where limited studies have been conducted. Based on the findings, we recommend that academic librarians engage with faculty through outreach and workshops to change perceptions of OA and the institutional repository
Behind Closed Gates: The Barriers to Self-Expression and Publication for Australian Young Adult Authors of OwnVoices Fiction
This article based on an empirical study of Australian authors argues that, despite the OwnVoices movement gathering momentum in Australia, there are still barriers and limitations for authors from marginalised communities within the Australian publishing industry. This is due to power imbalances in publishing spaces which silence marginalised writers, limiting the availability of their books to teenage readers
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