9,383 research outputs found
Evolving database systems : a persistent view
Submitted to POS7 This work was supported in St Andrews by EPSRC Grant GR/J67611 "Delivering the Benefits of Persistence"Orthogonal persistence ensures that information will exist for as long as it is useful, for which it must have the ability to evolve with the growing needs of the application systems that use it. This may involve evolution of the data, meta-data, programs and applications, as well as the users' perception of what the information models. The need for evolution has been well recognised in the traditional (data processing) database community and the cost of failing to evolve can be gauged by the resources being invested in interfacing with legacy systems. Zdonik has identified new classes of application, such as scientific, financial and hypermedia, that require new approaches to evolution. These applications are characterised by their need to store large amounts of data whose structure must evolve as it is discovered by the applications that use it. This requires that the data be mapped dynamically to an evolving schema. Here, we discuss the problems of evolution in these new classes of application within an orthogonally persistent environment and outline some approaches to these problems.Postprin
Linguistic Reflection in Java
Reflective systems allow their own structures to be altered from within. Here
we are concerned with a style of reflection, called linguistic reflection,
which is the ability of a running program to generate new program fragments and
to integrate these into its own execution. In particular we describe how this
kind of reflection may be provided in the compiler-based, strongly typed
object-oriented programming language Java. The advantages of the programming
technique include attaining high levels of genericity and accommodating system
evolution. These advantages are illustrated by an example taken from persistent
programming which shows how linguistic reflection allows functionality (program
code) to be generated on demand (Just-In-Time) from a generic specification and
integrated into the evolving running program. The technique is evaluated
against alternative implementation approaches with respect to efficiency,
safety and ease of use.Comment: 25 pages. Source code for examples at
http://www-ppg.dcs.st-and.ac.uk/Java/ReflectionExample/ Dynamic compilation
package at http://www-ppg.dcs.st-and.ac.uk/Java/DynamicCompilation
Non semi-simple sl(2) quantum invariants, spin case
Invariants of 3-manifolds from a non semi-simple category of modules over a
version of quantum sl(2) were obtained by the last three authors in
[arXiv:1404.7289]. In their construction the quantum parameter is a root of
unity of order where is odd or congruent to modulo . In this
paper we consider the remaining cases where is congruent to zero modulo
and produce invariants of -manifolds with colored links, equipped with
generalized spin structure. For a given -manifold , the relevant
generalized spin structures are (non canonically) parametrized by
.Comment: 13 pages, 16 figure
Oocyte cryopreservation as an adjunct to the assisted reproductive technologies
The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisherâs copy is included. See page 2 of PDF for this item.Keith L Harrison, Michelle T Lane, Jeremy C Osborn, Christine A Kirby, Regan Jeffrey, John H Esler and David Mollo
Which lipid measurement should we monitor? An analysis of the LIPID study
OBJECTIVES: To evaluate the optimal lipid to measure in monitoring patients, we assessed three factors that influence the choice of monitoring tests: (1) clinical validity; (2) responsiveness to therapy changes and (3) the size of the long-term âsignal-to-noiseâ ratio. DESIGN: Longitudinal analyses of repeated lipid measurement over 5â
years. SETTING: Subsidiary analysis of a Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) studyâa clinical trial in Australia, New Zealand and Finland. PARTICIPANTS: 9014 patients aged 31â75â
years with previous acute coronary syndromes. INTERVENTIONS: Patients were randomly assigned to 40â
mg daily pravastatin or placebo. PRIMARY AND SECONDARY OUTCOME MEASURES: We used data on serial lipid measurementsâat randomisation, 6â
months and 12â
months, and then annually to 5â
yearsâof total cholesterol; low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and their ratios; triglycerides; and apolipoproteins A and B and their ratio and their ability to predict coronary events. RESULTS: All the lipid measures were statistically significantly associated with future coronary events, but the associations between each of the three ratio measures (total or LDL cholesterol to HDL cholesterol, and apolipoprotein B to apolipoprotein A1) and the time to a coronary event were better than those for any of the single lipid measures. The two cholesterol ratios also ranked highly for the long-term signal-to-noise ratios. However, LDL cholesterol and non-HDL cholesterol showed the most responsiveness to treatment change. CONCLUSIONS: Lipid monitoring is increasingly common, but current guidelines vary. No single measure was best on all three criteria. Total cholesterol did not rank highly on any single criterion. However, measurements based on cholesterol subfractionsânon-HDL cholesterol (total cholesterol minus HDL cholesterol) and the two ratiosâappeared superior to total cholesterol or any of the apolipoprotein options. Guidelines should consider using non-HDL cholesterol or a ratio measure for initial treatment decisions and subsequent monitoring
Topological Optimization of the Evaluation of Finite Element Matrices
We present a topological framework for finding low-flop algorithms for
evaluating element stiffness matrices associated with multilinear forms for
finite element methods posed over straight-sided affine domains. This framework
relies on phrasing the computation on each element as the contraction of each
collection of reference element tensors with an element-specific geometric
tensor. We then present a new concept of complexity-reducing relations that
serve as distance relations between these reference element tensors. This
notion sets up a graph-theoretic context in which we may find an optimized
algorithm by computing a minimum spanning tree. We present experimental results
for some common multilinear forms showing significant reductions in operation
count and also discuss some efficient algorithms for building the graph we use
for the optimization
In-flight measurement of ice growth on an airfoil using an array of ultrasonic transducers
Results of preliminary tests to measure ice growth on an airfoil during flight icing conditions are presented. Ultrasonic pulse echo measurements of ice thickness are obtained from an array of eight ultrasonic transducers mounted flush with the leading edge of the airfoil. These thickness measurements are used to document the evolution of the ice shape during the encounter in the form of successive ice profiles. Results from 3 research flights are presented and discussed. The accuracy of the ultrasonic measurements is found to be within 0.5 mm of mechanical and stereo photograph measurements of the ice accretion
Formation and structural characterization of Ni nanoparticles embedded in SiOâ
Face-centered cubic Ni nanoparticles were formed in SiOâ by ion implantation and thermal annealing. Small-angle x-ray scattering in conjunction with transmission electron microscopy was used to determine the nanoparticle size as a function of annealing temperature, whereas the local atomic structure was measured with x-ray absorption spectroscopy. The influence of finite-size effects on the nanoparticle structural properties was readily apparent and included a decrease in coordination number and bond length and an increase in structural disorder for decreasing nanoparticle size. Such results are consistent with the non-negligible surface-to-volume ratio characteristic of nanoparticles. In addition, temperature-dependent x-ray absorption spectroscopy measurements showed the mean vibrational frequency (as obtained from the Einstein temperature) decreased with decreasing nanoparticle size. This reduction was attributed to the greater influence of the loosely bound, under-coordinated surface atoms prevailing over the effects of capillary pressure, the former enhancing the low frequency modes of the vibrational density of statesThis work was financially supported by the Australian
Synchrotron and the Australian Research Council with access to equipment provided by the Australian Nanofabrication
Facility
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