213 research outputs found
A quasi-linear model of electromagnetic turbulent transport and its application to flux-driven transport predictions for STEP
No full textA quasi-linear reduced transport model is developed from a database of
high- electromagnetic nonlinear gyrokinetic simulations performed with
Spherical Tokamak for Energy Production (STEP) relevant parameters. The
quasi-linear model is fully electromagnetic and accounts for the effect of
equilibrium flow shear using a novel approach. Its flux predictions are shown
to agree quantitatively with predictions from local nonlinear gyrokinetic
simulations across a broad range of STEP-relevant local equilibria. This
reduced transport model is implemented in the T3D transport solver that is used
to perform the first flux-driven simulations for STEP to account for transport
from hybrid-KBM turbulence, which dominates over a wide region of the core
plasma. Nonlinear gyrokinetic simulations of the final transport steady state
from T3D return turbulent fluxes that are consistent with the reduced model,
indicating that the quasi-linear model may also be appropriate for describing
the transport steady state. Within the assumption considered here, our
simulations support the existence of a transport steady state in STEP with a
fusion power comparable to that in the burning flat-top of the conceptual
design, but do not demonstrate how this state can be accessed
A useful exercise : the context, content, and practical application of W. H. Alington's 'Thesis on the Theory of Architectural Design'
No full textWith his thesis, entitled Thesis on the Theory of Architectural Design, Alington went against convention by submitting a written work at a time when a drawn, practical design project was the expected hand-in. He believed that the written word would allow him to better handle the abstract considerations that are necessary to properly intellectualise and communicate a comprehensive understanding of architecture. The outcome was a document, based on the primacy of the act of architectural experience, which reveals a humanistic understanding of architecture's role in society.
In order to understand the context for the production of Alington's thesis, this paper employs Alinoton's own personal recollections and primary records as the basis for the creation of a 'life-story'. This 'other' narrative sits amongst the dominant legitimising narratives that structure New Zealand's received architectural history. Yet it is inevitable that at some point these narratives will conflict. It is argued that Alington's intellectualisation of architectural experience is one such point that raises questions about the pragmatism that has come to typify the architectural canon-forming process in this country. This thesis does not attempt to discover these discrepancies, nor does it attempt to resolve them. It instead allows Alington's story - his thoughts, writings, and built work - to speak for itself.
This research seeks to understand the milieu within which Alington devised his architectural philosophy; it canvasses the key environments, including the Ministry of Works, the Wellington Architectural Centre, and the Auckland University College School of Architecture, as significant influences on this formative part of his career. Secondly, it engages with Alington's ideas through a close reading of his writing, and the major texts that it drew from. Finally, by taking Alington's own house as a case study, it explores how these ideas have influenced his built work - an oeuvre of considerable (but as yet, largely unconsidered) importance to the history of Modern architecture in New Zealand
This research presents the development of W H Alington's personal conception or architecture; from its formative influences, through its written manifestation, to its application in his built work
On the importance of parallel magnetic-field fluctuations for electromagnetic instabilities in STEP
No full textThis paper discusses the importance of parallel perturbations of the magnetic-field in gyrokinetic simulations of electromagnetic instabilities and turbulence at mid-radius in the burning plasma phase of the conceptual high-β, reactor-scale, tight-aspect-ratio tokamak STEP. Previous studies have revealed the presence of unstable hybrid kinetic ballooning modes (hKBMs) and subdominant microtearing modes at binormal scales approaching the ion Larmor radius. In this STEP plasma it was found that the hKBM requires the inclusion of parallel magnetic-field perturbations to be linearly unstable. Here, the extent to which the inclusion of fluctuations in the parallel magnetic-field can be relaxed is explored through gyrokinetic simulations. In particular, the frequently used MHD approximation (dropping δB∥ and setting the ∇B drift frequency equal to the curvature drift frequency) is discussed and simulations explore whether this approximation is useful for modelling STEP plasmas. It is shown that the MHD approximation can reproduce some of the linear properties of the full STEP gyrokinetic system, but is too stable at low ky and nonlinear simulations using the MHD approximation result in very different transport states. It is demonstrated that the MHD approximation is challenged by the high β′ values in STEP, and that the approximation improves considerably at lower β′ . Furthermore, it is shown that the sensitivity of STEP to δB∥ fluctuations is primarily because the plasma sits close to marginality and it is shown that in slightly more strongly driven conditions the hKBM is unstable without δB∥. Crucially, it is demonstrated that the state of large transport typically predicted by local electromagnetic gyrokinetic simulations of STEP plasmas is not solely due to δB∥ physics
Sequential assessment of bowel function and anorectal physiology after anterior resection for cancer: a prospective cohort study
No full textAim: The aim of this study was to investigate changes in bowel function and anorectal physiology (ARP) after anterior resection for colorectal cancer. Method: Patients were recruited from November 2006 to September 2008. Cleveland Clinic Incontinence (CCI) scores and stool frequency were determined by patient questionnaires before surgery (t
0) and at three (t
3), six (t
6), nine (t
9) and 12 (t
12) months after restoration of intestinal continuity. ARP measurements were recorded at T
0, T
3 and T
12. Endoanal ultrasound was performed at T
0 and T
12. Results: Eighty-nine patients were included. CCI score increased postoperatively then normalized, whereas stool frequency did not change. Patients who had neoadjuvant radiotherapy or a lower anastomosis had increased incontinence and stool frequency in the postoperative period, whereas those with defunctioning stomas or open surgery had increased stool frequency alone. Maximum resting pressure, volume at first urge and maximum rectal tolerance were reduced throughout the postoperative period. Radiotherapy, lower anastomosis and defunctioning stoma (but not operative approach) altered manometric parameters postoperatively. Maximum rectal tolerance correlated with incontinence and first urge with stool frequency. The length of the anterior internal anal sphincter decreased postoperatively. Conclusions: Incontinence recovers in the first year after anterior resection. Radiotherapy, lower anastomosis, defunctioning stoma and open surgery have a negative influence on bowel function. ARP may be useful if bowel dysfunction persists beyond 12 months.
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An Evolving Insight into Chiral H‑Bond Catalyzed Aza-Henry Reactions: A Cooperative Role for Noncovalent Attractive Interactions Unveiled by Density Functional Theory
No full textThe
role of cooperative effects arising from noncovalent attractive
interactions as a vital factor governing stereoinduction in chiral
H-bond catalyzed aza-Henry reactions is reported. Supporting this
finding were density functional theory (DFT) calculations which revealed
a shape and size dependency existed between the catalyst and substrates
that when matched lead to high enantioselectivity, as reflected by
favorable activation parameters. Associated with optimal catalyst
and substrate pairing were a closed catalytic binding pocket and a
synclinal orientation of the substrates that reinforced favorable
stereoelectronic effects and dispersive type forces. Meanwhile, unfavorable
steric interactions were found to be a dominant effect controlling
diastereoselection
Repeatability of innervation zone identification in the external anal sphincter muscle
No full textKnowledge of the distribution of the innervation zones (IZs) of the external anal sphincter (EAS) may be useful for preventing anal sphincter incompetence during vaginal delivery. A method proposed for the automatic estimation of the distribution of IZs of EAS from high-density surface electromyography (EMG) was evaluated for repeatability in continent volunteers. Methods: In 13 healthy female subjects (age: 35 11 years) surface EMG signals were acquired using an anal probe with three circumferential electrode arrays (of 16 contacts each) at different depths within the anal canal (15mm distance between the centers of adjacent arrays), during four independent experimental sessions. Three maximal voluntary contractions (MVCs) of 10 sec were performed for each session for a total of 12 contractions per subject. Repeatability of the estimation of the distribution of IZ was tested by evaluating the coefficient of multiple correlations (CMC) between the IZ distributions estimated from the signals recorded from each subject. Results: A high repeatability (CMC > 0.8) was found comparing IZ distributions estimated from signals recorded by each array within the same session. A slightly lower value was obtained considering signals recorded during different sessions (CMC > 0.7), but a higher value (CMC > 0.8) was obtained after aligning the estimated IZ distributions. The realignment compensates for the operator's error in repositioning the probe in the same position during different sessions. Conclusion: This result justifies clinical studies using high-density surface EMG in routine examinations, providing information about IZs of EAS and assessing the possibilities of preventing neuronal trauma during vaginal delivery
Sight and Sensation:Observations on I.M. Pei’s Approach to Composition
No full textThis paper examines I.M. Pei’s approach to the problem of form and space generation. Although Pei has not set out a comprehensive statement on his process for conceiving architectural form, there are specific ambitions discussed throughout published interviews and evidence of definite circulatory, spatial, and volumetric devices in the built work. The paper reveals clues to Pei’s sensibility in this work, a sensibility which, it is argued, privileges dynamic, nonperspectival relations accommodating multiple viewpoints as distinct from what the architect himself characterises as static conditions resulting from single vanishing point perspective. As an underlying proposition, and in order to provisionally place Pei’s work within architecture’s larger historical trajectory, the idea of a nonperspectival conception of space as formulated by Giulio Carlo Argan is used in an analysis of the composition techniques in Pei’s thinking and practice. In order to test this proposition, the paper considers published interviews and undertakes an initial examination of the Everson Museum of Art (Syracuse, 1961-1968), the National Gallery of Art East Building (Washington D.C., 1968-1978), and the Morton H. Meyerson Symphony Center (Dallas, 1982-1989). The paper asks such questions as: Which concepts of space are at work in the projects? What differences in strategy and effect are revealed in the three projects and do they align with Pei’s stated ambition to create an architecture of movement formed by multiple viewpoints? More pointed is the question: Do the projects realise different kinds of space and if so is one better aligned to theories of sight or sensation? In addressing an underlying SAHANZ 2018 conference theme concerning the relationship between conceiving and shaping architectural space, the paper reveals untheorised aspects of Pei’s manner of composing built form, and makes a modest contribution to scholarship on post-1950s architectural theory
Safe distances for blasting wiring from commonly encountered underground electromagnetic energy sources.
No full text"The use of electromagnetic field producing equipment in underground coal mining operations can only be expected to grow. The use of this equipment in underground mining operations is hampered by the possibility of their electromagnetic fields interacting with the electric blasting cap operations commonly carried out in the mines. Such interactions can have at least two results bearing directly on mine safety: premature initiation of the cap, either in its normal shot location or during hookup or transportation; and dudding of the cap so that normal firing operations do not cause initiation, thereby leaving unexploded high explosives after normal firing. The experimental work on this project was directed to determining the magnetic field distribution around typical underground current carrying conductor configurations." - NIOSHTIC-2NIOSHTIC no. 20030897Contract no. 5032802
A Au(I)-Precatalyst with a Cyclopropenium Counterion: An Unusual Ion Pair
No full textThe
synthesis and X-ray crystal structure of a novel Au(I)-precatalyst
applied to intermolecular alkyne hydroamination is reported. Density
functional theory (DFT) calculations revealed the cyclopropenium counterion
of this Au(I)-precatalyst imparts stability through H-bonding and
other noncovalent interactions
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