41,428 research outputs found
A Systems-Based Approach to the Identification of User/Infrastructure Interdependencies as a Precursor to Identifying Opportunities to Improve Infrastructure Project Value/Cost Ratios
The bulk of the investment needed for infrastructure renewal in the United Kingdom will have to come from private
sector investors, who will require attractive value/cost ratios. Government recognises infrastructure interdependencies
can help deliver these, but returns remain uncertain. New business models are required to overcome this problem,
which take account of enterprise-centred infrastructure interdependencies (interdependencies between social and
economic enterprises and the infrastructures they use). The complex and closely coupled nature of enterprise and
infrastructure systems can stand in the way of identifying these interdependencies; however, model-based systems
engineering techniques offer a framework for dealing with this complexity. This paper describes research that the
iBUILD project is doing to develop a methodology for modelling the interdependencies between infrastructure and
the enterprises that use it, as a precursor to identifying opportunities to improve infrastructure project value/cost
ratios. The methodology involves: identifying the suite of policy, strategy and operational documents relating to the
enterprise-of-interest; eliciting system data from the documents and integrating it to create an enterprise system
model; and, generating N2 diagrams from the model to identify the interdependencies
Maser Source Finding Methods in HOPS
The {\bf H}{\bf O} Southern Galactic {\bf P}lane {\bf S}urvey (HOPS) has
observed 100 square degrees of the Galactic plane, using the Mopra radio
telescope to search for emission from multiple spectral lines in the 12\,mm
band (19.5\,--\,27.5\,GHz). Perhaps the most important of these spectral lines
is the 22.2\,GHz water maser transition. We describe the methods used to
identify water maser candidates and subsequent confirmation of the sources. Our
methods involve a simple determination of likely candidates by searching peak
emission maps, utilising the intrinsic nature of water maser emission -
spatially unresolved and spectrally narrow-lined. We estimate completeness
limits and compare our method with results from the {\sc Duchamp} source
finder. We find that the two methods perform similarly. We conclude that the
similarity in performance is due to the intrinsic limitation of the noise
characteristics of the data. The advantages of our method are that it is
slightly more efficient in eliminating spurious detections and is simple to
implement. The disadvantage is that it is a manual method of finding sources
and so is not practical on datasets much larger than HOPS, or for datasets with
extended emission that needs to be characterised. We outline a two-stage method
for the most efficient means of finding masers, using {\sc Duchamp}.Comment: 8 pages, 1 table, 4 figures. Accepted for publication in PASA special
issue on Source Finding & Visualisatio
Kinematics of a hot massive accretion disk candidate
Characterizing rotation, infall and accretion disks around high-mass
protostars is an important topic in massive star formation research. With the
Australia Telescope Compact Array and the Very Large Array we studied a massive
disk candidate at high angular resolution in ammonia (NH3(4,4) & (5,5)) tracing
the warm disk but not the envelope. The observations resolved at ~0.4''
resolution (corresponding to ~1400AU) a velocity gradient indicative of
rotation perpendicular to the molecular outflow. Assuming a Keplerian accretion
disk, the estimated protostar-disk mass would be high, similar to the
protostellar mass. Furthermore, the position-velocity diagram exhibits
additional deviation from a Keplerian rotation profile which may be caused by
infalling gas and/or a self-gravitating disk. Moreover, a large fraction of the
rotating gas is at temperatures >100K, markedly different to typical low-mass
accretion disks. In addition, we resolve a central double-lobe cm continuum
structure perpendicular to the rotation. We identify this with an ionized,
optically thick jet.Comment: 5 pages, 3 figures, accepted for Astrophysical Journal Letters, a
high-resolution version of the draft can be found at
http://www.mpia.de/homes/beuther/papers.htm
On The Complexity and Completeness of Static Constraints for Breaking Row and Column Symmetry
We consider a common type of symmetry where we have a matrix of decision
variables with interchangeable rows and columns. A simple and efficient method
to deal with such row and column symmetry is to post symmetry breaking
constraints like DOUBLELEX and SNAKELEX. We provide a number of positive and
negative results on posting such symmetry breaking constraints. On the positive
side, we prove that we can compute in polynomial time a unique representative
of an equivalence class in a matrix model with row and column symmetry if the
number of rows (or of columns) is bounded and in a number of other special
cases. On the negative side, we show that whilst DOUBLELEX and SNAKELEX are
often effective in practice, they can leave a large number of symmetric
solutions in the worst case. In addition, we prove that propagating DOUBLELEX
completely is NP-hard. Finally we consider how to break row, column and value
symmetry, correcting a result in the literature about the safeness of combining
different symmetry breaking constraints. We end with the first experimental
study on how much symmetry is left by DOUBLELEX and SNAKELEX on some benchmark
problems.Comment: To appear in the Proceedings of the 16th International Conference on
Principles and Practice of Constraint Programming (CP 2010
The impact of preschool feeding programmes on the growth of disadvantaged young children in developing countries: a systematic review of randomised trials
Background: Childhood malnutrition in developing countries contributes to developmental delays, as well as increased morbidity and mortality. The effectiveness of feeding programmes as a strategy to improve childhood malnutrition has been questioned.Objective: A systematic review was undertaken to examine the effectiveness of preschool feeding programmes in fostering the growth of children in developing countries.Design: A systematic literature search was undertaken to identify published studies that related to the objective. Studies had to be randomised intervention studies that reported on the growth outcomes of children from birth to six years of age in order to be included.Setting: An initial literature search yielded 59 studies, of which 44 were excluded based on initial screening. Five more were omitted based on detailed data extraction. Ten studies met the inclusion criteria. The results of these studies were compared and narratively described in the context of the objective.Results: The studies showed a great level of heterogeneity with regard to sample characteristics, intervention and reporting of results. In the context of recovery from malnutrition, most studies reported there to be a positive effect from feeding programmes. In studies that reported on weight gain, those that employed a supervised intake of food supplements resulted in higher rates of weight gain. Micronutrient fortification was described as having a positive influence on the rate of linear growth in studies that reported on linear growth. Intensive nutrition education aimed at mothers and caregivers is a sustainable way in which to change child feeding behaviour and may contribute to the effectiveness of nutrition intervention.Conclusion: The limitations of the study included the following: there was a low number (59) of identified studies in the initial search because of the use of limited search terms, assessment of risk of bias was carried out by only one reviewer using a self-designed grading system, there were high levels of heterogeneity, and less than half of the individual studies were rated to be of a high quality. In view of these limitations, no firm conclusion can be drawn. Additional research, aimed at determining the impact of supplementary feeding programmes in supporting the growth of disadvantaged children, is encouraged.Keywords: preschool feeding programmes, growth, disadvantaged children, developing countrie
New ammonia masers towards NGC6334I
We report the detection of new ammonia masers in the non-metastable (8,6) and
(11,9) transitions towards the massive star forming region NGC6334I.
Observations were made with the ATCA interferometer and the emitting region
appears unresolved in the 2.7" x 0.8" beam, with deconvolved sizes less than an
arcsecond. We estimate peak brightness temperatures of 7.8 x 10^5 and 1.2 x
10^5 K for the (8,6) and (11,9) transitions, respectively. The masers appear
coincident both spatially and in velocity with a previously detected ammonia
(6,6) maser. We also suggest that emission in the (10,9), (9,9) and (7,6)
transitions may also be masers, based on their narrow line widths and
overlapping velocity ranges with the above masers, as observed with the
single-dish Mopra radiotelescope
The need for best practice standards in electronic governance of patient medical records to facilitate innovation
Background : Optimising the use of electronic data offers many opportunities to health services, particularly in rural and remote areas. These include reducing the effect of distance on access to clinical information and sharing information where there are multiple service providers for a single patient. The increasing compilation of large electronic databases of patient information and the ease with which electronic information can be transferred has raised concerns about the privacy and confidentiality of such records.Aims & rationale/Objectives : This review aims to identify legal and ethical standards for areas of electronic governance where a lack of clarity may currently impede innovation in health service delivery.Methods : This paper describes best practices for storage and transfer of electronic patient data based on an examination of Australian legislative requirements and a review of a number of current models. This will firstly allow us to identify basic legal requirements of electronic governance as well as areas of ambiguity not fully addressed by legislation. An examination of current models will suggest recommendations for best practice in areas lacking sufficient legal guidance.Principal findings : We have identified the following four areas of importance, and shall discuss relevant details:1) Patients\u27 right of ownership to electronic patient records. 2) Custodial issues with data stored in centralised health care institutions 3) IT Security, including hierarchical level access, data encryption, data transfer standards and physical security 4) Software applications usage.Discussion : Our examination of several models of best practice for the transfer of electronic patient data, both in Australia and internationally, identifies and clarifies many unresolved issues of electronic governance. This paper will also inform future policy in this area.Implications : Clarification will facilitate the future development of beneficial technology-based innovations by rural health services.Presentation type : Poster <br /
Enduring Originalism
If our law requires originalism in constitutional interpretation, then that would be a good reason to be an originalist. This insight animates what many have begun to call the positive turn in originalism. Defenses of originalism in this vein are positive in that they are based on the status of the Constitution, and constitutional law, as positive law. This approach shifts focus away from abstract conceptual or normative arguments about interpretation and focuses instead on how we actually understand and apply the Constitution as law. On these grounds, originalism rests on a factual claim about the content of our law: that we regard the framers\u27 law, and any other further lawful changes, as our law today. If we do not, originalism is not the law and perhaps should be abandoned in favor of what is.
The Article proceeds as follows. Part I outlines the positive turn in originalism, one of the most important and promising developments in originalist theory in recent years. After noting the approach\u27s benefits, we offer jurisprudential objections to its foundations. Part II explains how the positive turn\u27s appealing form of originalism is better grounded in a broader understanding of the moral point of constitutions. Far from being a musty, sectarian artifact, the classical natural law tradition of reasoning about positive law\u27s moral purpose animated the framers\u27 understanding of our Constitution and provides the most persuasive reason for continued adherence to that original law today. Part III addresses the difficulties that today\u27s nonoriginalist practices present to one normatively committed to original law, while also explaining why the appeal of originalism endures in the face of those challenges
VLASSICK: The VLA Sky Survey in the Central Kiloparsec
At a distance of 8 kpc, the center of our Galaxy is the nearest galactic
nucleus, and has been the subject of numerous key projects undertaken by great
observatories such as Chandra, Spitzer, and Herschel. However, there are still
no surveys of molecular gas properties in the Galactic center with less than
30" (1 pc) resolution. There is also no sensitive polarization survey of this
region, despite numerous nonthermal magnetic features apparently unique to the
central 300 parsecs. In this paper, we outline the potential the VLASS has to
fill this gap. We assess multiple considerations in observing the Galactic
center, and recommend a C-band survey with 10 micro-Jy continuum RMS and
sensitive to molecular gas with densities greater than 10^4 cm^{-3}, covering
17 square degrees in both DnC and CnB configurations ( resolution ~5"),
totaling 750 hours of observing time. Ultimately, we wish to note that the
upgraded VLA is not just optimized for fast continuum surveys, but has a
powerful correlator capable of simultaneously observing continuum emission and
dozens of molecular and recombination lines. This is an enormous strength that
should be fully exploited and highlighted by the VLASS, and which is ideally
suited for surveying the center of our Galaxy.Comment: 13 pages, 3 figures, a White Paper submitted to provide input in
planning the Very Large Array Sky Surve
- …