2,961 research outputs found
Molecular dynamics as a tool to study heterogeneity in zeolites - Effect of Na cations on diffusion of CO and N in Na-ZSM-5
Zeolites typically contain extra-framework cations to charge-compensate for trivalent Al atom substitutions in the SiO framework. These cations, such as Na, directly interact with quadrupolar guest molecules, such as CO and N, which move through their micropores, causing energetic heterogeneity. To assess the effects of heterogeneity in Na-ZSM-5 on diffusion of CO and N, molecular dynamics (MD) simulations are carried out. In silicalite-1, the pure-silicon form of ZSM-5, the self-diffusivity exhibits a monotonic decrease with molecular loading, while the corrected diffusivity shows a relatively constant value. In contrast, the Na cations cause a maximum or a flat profile over molecular loading for the self- and corrected diffusivities of CO at T=200 and 300K, while the cations only have minimal impact on the diffusivity of N. The MD simulations allow us to identify energy basins or sites at which guest molecules spend a relatively long time, and construct a coarse-grained lattice representation for the pore network. Average residence times at these sites are calculated for both species. The trends observed in the residence times correlate to the trends observed in the diffusivity. The residence times for CO at T=200K are long at low loading, but decrease with loading as additional CO molecules compete to stay close to a cation. In contrast, the residence times for N are relatively insensitive to the cations, only mildly increasing near a cation. This difference in behavior can be associated to the quadrupole moments of these molecules
Visitor perceptions of captive wildlife tourism in a Western Australian natural setting
Wildlife tourism involves a broad sweep of experiences that includes all of the aspects of the tourism genre with the distinguishing feature of animals as the primary attraction. The uniqueness of Australian wildlife in combination with factors such as remoteness and rarity appear to have provided the ideal context for successful wildlife tourism operations. Barna Mia, located in a large remnant woodland in the central southern wheatbelt of Western Australia, is approximately 165 km southeast of the state's capital, Perth. Dryandra Woodland, the location of Banra Mia consists of a closely grouped and connected cluster of native remnant vegetation blocks. The enclosure is surrounded by electrified, vermin proof fencing to keep feral predators out and the captive fauna in. The results of the visitor survey at Barna Mia suggested the experience provided a great sense of satisfaction amongst respondents. This was both in terms of the overall satisfaction as well as satisfaction with specific parts of the experience. The feeling of being 'in the wild' may have been enhanced by the lack of barriers between visitors and the animals and the absence of constraints on animal movement through the enclosure. Improving the operation of Barna Mia as an attraction in itself and as part of the Dryandra Woodland product may serve to improve its success as an attraction. However, an innately attractive tourism experience cannot work without appropriate integration within the specific wildlife tourism product of Dryandra Woodland, while coordination with tourism on a regional scale is also important
Esther “Etty” Hillesum: An Annotated and Summarized Bibliography of Works in English through 2010
GEODESIC STRUCTURE IN SCHWARZSCHILD GEOMETRY WITH EXTENSIONS IN HIGHER DIMENSIONAL SPACETIMES
From Birkoff\u27s theorem, the geometry in four spacetime dimensions outside a spherically symmetric and static, gravitating source must be given by the Schwarzschild metric. This metric therefore satisfies the Einstein vacuum equations. If the mass which gives rise to the Schwarzschild spacetime geometry is concentrated within a radius of r=2M, a black hole will form. Non-accelerating particles (freely falling) traveling through this geometry will do so along parametrized curves called geodesics, which are curved space generalizations of straight paths. These geodesics can be found by solving the geodesic equation. In this thesis, the geodesic structure in the Schwarzschild geometry is investigated with an attempt to generalize the solution to higher dimensions
Impact of uncertainties in inorganic chemical rate constants on tropospheric composition and ozone radiative forcing
Chemical rate constants determine the composi- tion of the atmosphere and how this composition has changed over time. They are central to our understanding of climate change and air quality degradation. Atmospheric chemistry models, whether online or offline, box, regional or global, use these rate constants. Expert panels evaluate laboratory mea- surements, making recommendations for the rate constants that should be used. This results in very similar or identi- cal rate constants being used by all models. The inherent un- certainties in these recommendations are, in general, there- fore ignored. We explore the impact of these uncertainties on the composition of the troposphere using the GEOS-Chem chemistry transport model. Based on the Jet Propulsion Lab- oratory (JPL) and International Union of Pure and Applied Chemistry (IUPAC) evaluations we assess the influence of 50 mainly inorganic rate constants and 10 photolysis rates on tropospheric composition through the use of the GEOS- Chem chemistry transport model. We assess the impact on four standard metrics: an- nual mean tropospheric ozone burden, surface ozone and tropospheric OH concentrations, and tropospheric methane lifetime. Uncertainty in the rate constants for M NO2 +OH−→HNO3 and O3 +NO→NO2 +O2 are the two largest sources of uncertainty in these metrics. The ab- solute magnitude of the change in the metrics is similar if rate constants are increased or decreased by their σ values. We investigate two methods of assessing these uncertainties, addition in quadrature and a Monte Carlo approach, and con- clude they give similar outcomes. Combining the uncertain- ties across the 60 reactions gives overall uncertainties on the annual mean tropospheric ozone burden, surface ozone and tropospheric OH concentrations, and tropospheric methane lifetime of 10, 11, 16 and 16 %, respectively. These are larger than the spread between models in recent model intercompar- isons. Remote regions such as the tropics, poles and upper troposphere are most uncertain. This chemical uncertainty is sufficiently large to suggest that rate constant uncertainty should be considered alongside other processes when model results disagree with measurement. Calculations for the pre-industrial simulation allow a tropospheric ozone radiative forcing to be calculated of 0.412 ± 0.062 W m−2 . This uncertainty (13 %) is compara- ble to the inter-model spread in ozone radiative forcing found in previous model–model intercomparison studies where the rate constants used in the models are all identical or very similar. Thus, the uncertainty of tropospheric ozone radia- tive forcing should expanded to include this additional source of uncertainty. These rate constant uncertainties are signifi- cant and suggest that refinement of supposedly well-known chemical rate constants should be considered alongside other improvements to enhance our understanding of atmospheric processes
Making postgraduate students and supervisors aware of the role of emotions in the PhD process
Emotions are an integral part of the PhD process. A range of emotions are common and to be expected. How do emotions affect the PhD process for both postgraduate students and their supervisors? How can we make our emotions work positively for us in the PhD process? To explore answers to these questions, three lecturers currently supervising postgraduates and three postgraduates at various stages in their doctoral studies collectively pooled their experiences. We developed an interactive workshop that was recently conducted for postgraduate students at Murdoch University and at the Australian Association for Social Research annual conference 2002.
This presentation will explore the role that emotions play in the PhD process and how supervisors and postgraduates alike can benefit from reflecting on this issue. A number of practical (and humorous) tips will be provided as well as examples from others' PhD experiences. The role of emotions at the beginning, middle and end of a PhD program will be explored. The data collection and analysis phases are a time when emotions may run riot. Trepidation is especially common when fieldwork or data collection is involved, as is anger when postgraduate's views about how the world works are challenged and then sadness (and relief!) when the data collection phase is finished. We will discuss how supervisors can assist their postgraduates to make these feelings work for them. The presentation will also explore the emotions that arise from the supervisor-postgraduate partnership
Keyed Non-Parametric Hypothesis Tests
The recent popularity of machine learning calls for a deeper understanding of
AI security. Amongst the numerous AI threats published so far, poisoning
attacks currently attract considerable attention. In a poisoning attack the
opponent partially tampers the dataset used for learning to mislead the
classifier during the testing phase.
This paper proposes a new protection strategy against poisoning attacks. The
technique relies on a new primitive called keyed non-parametric hypothesis
tests allowing to evaluate under adversarial conditions the training input's
conformance with a previously learned distribution . To do so we
use a secret key unknown to the opponent.
Keyed non-parametric hypothesis tests differs from classical tests in that
the secrecy of prevents the opponent from misleading the keyed test
into concluding that a (significantly) tampered dataset belongs to
.Comment: Paper published in NSS 201
Physiotherapy for Patients with Sciatica Awaiting Lumbar Micro-discectomy Surgery: A Nested, Qualitative Study of Patients' Views and Experiences
Background and Purpose
Sciatica is a common clinical condition that can be extremely painful, disabling and life‐changing. Whether conservative or surgical treatment for sciatica secondary to an intervertebral disc prolapse is most effective is still much debated. An important component of conservative treatment is physiotherapy, which aims to promote physical and psychological health for the patient, whilst resorption of the disc takes place. This paper reports a qualitative study of patients' views and experiences of a bespoke physiotherapy intervention for the treatment of sciatica.
Methods
A qualitative study nested within a pilot randomized controlled trial of bespoke physiotherapy for the treatment of patients with sciatica awaiting lumbar microdiscectomy surgery. Patients randomized to receive bespoke physiotherapy in the intervention arm of the trial were invited to take part in semi‐structured interviews. Twenty‐one in‐depth, semi‐structured interviews took place. All interviews were recorded, fully transcribed and thematically analysed.
Results
Most patients in the sample found the physiotherapy valuable, appreciating the individual nature of the approach, the exercises to reduce pain and discomfort, techniques for improving functional spinal movement, walking and dynamic posture, and manual therapy and cardiovascular exercise. A small number did not find the physiotherapy of benefit. Sixteen patients in the sample went on to proceed with surgery, but most of these found value in having had the physiotherapy first.
Discussion
Many patients with sciatica appreciate the value of physiotherapy prior to surgery. Future research should examine patients' experiences of bespoke physiotherapy delivered within primary care
Application of Lev Vygotsky’s Sociocultural Approach to Foster Students’ Understanding and Learning Performance
The current study endeavours to explore the application of the Vygotskian sociocultural approach to students’ cognitive development, particularly as related to the employment of experiential and peer learning, from both teacher and student perspectives. This is followed by a discussion of the inferences made in relation to the contributions of experiential and peer learning as salient educational delivery modes. As such, a presentation of teachers’ recounts about learning to teach, and students’ reflections on teaching to learn are provided. Finally, the current study concludes with: 1) Insightful erudition learning and teaching curves impacting students’ performance, retention and progression; and 2) Directions for future research in the area
Autobiography in Disarray: Setouchi Jakuchō’s Use of Biography as Self-Expression in \u3ci\u3eBeauty in Disarray\u3c/i\u3e
The aim of this thesis is to analyze Setouchi Jakuchō’s biographical novel Beauty in Disarray (美は乱調にあり, 1966), through the lens of biographical writing as the author’s self-expression. Beauty in Disarray follows Seitō member Itō Noe from her adolescence in the spring of 1911 into her adulthood and ends abruptly with the “Hikage Teahouse Incident” in 1916, when Ōsugi Sakae, who would later go on to marry Itō, is stabbed by a jealous Kamichika Ichiko, another figured tied heavily to Seitō. Aside from the main character of Itō Noe, Beauty in Disarray also features several important members of Seitō and of the Japanese literary scene of the 1910s, such as Hiratsuka Raichō, and I include Setouchi’s treatment of these historical figures in my assessment of the work. Many literary figures featured in Beauty in Disarray were feminist and/or political activists, and I argue that it was Setouchi’s own interest in feminism and political activism that drew her to creating a novelization of the dramatic life of Itō Noe
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