18,662 research outputs found
Towards an interoperable healthcare information infrastructure - working from the bottom up
Historically, the healthcare system has not made effective use of information technology. On the face of things, it would seem to provide a natural and richly varied domain in which to target benefit from IT solutions. But history shows that it is one of the most difficult domains in which to bring them to fruition. This paper provides an overview of the changing context and information requirements of healthcare that help to explain these characteristics.First and foremost, the disciplines and professions that healthcare encompasses have immense complexity and diversity to deal with, in structuring knowledge about what medicine and healthcare are, how they function, and what differentiates good practice and good performance. The need to maintain macro-economic stability of the health service, faced with this and many other uncertainties, means that management bottom lines predominate over choices and decisions that have to be made within everyday individual patient services. Individual practice and care, the bedrock of healthcare, is, for this and other reasons, more and more subject to professional and managerial control and regulation.One characteristic of organisations shown to be good at making effective use of IT is their capacity to devolve decisions within the organisation to where they can be best made, for the purpose of meeting their customers' needs. IT should, in this context, contribute as an enabler and not as an enforcer of good information services. The information infrastructure must work effectively, both top down and bottom up, to accommodate these countervailing pressures. This issue is explored in the context of infrastructure to support electronic health records.Because of the diverse and changing requirements of the huge healthcare sector, and the need to sustain health records over many decades, standardised systems must concentrate on doing the easier things well and as simply as possible, while accommodating immense diversity of requirements and practice. The manner in which the healthcare information infrastructure can be formulated and implemented to meet useful practical goals is explored, in the context of two case studies of research in CHIME at UCL and their user communities.Healthcare has severe problems both as a provider of information and as a purchaser of information systems. This has an impact on both its customer and its supplier relationships. Healthcare needs to become a better purchaser, more aware and realistic about what technology can and cannot do and where research is needed. Industry needs a greater awareness of the complexity of the healthcare domain, and the subtle ways in which information is part of the basic contract between healthcare professionals and patients, and the trust and understanding that must exist between them. It is an ideal domain for deeper collaboration between academic institutions and industry
Optical and ROSAT X-ray observations of the dwarf nova OY Carinae in superoutburst and quiescence
We present ROSAT X-ray and optical light curves of the 1994 February
superoutburst of the eclipsing SU UMa dwarf nova OY Carinae. There is no
eclipse of the flux in the ROSAT HRI light curve. Contemporaneous `wide B' band
optical light curves show extensive superhump activity and dips at superhump
maximum. Eclipse mapping of these optical light curves reveals a disc with a
considerable physical flare, even three days into the superoutburst decline.
We include a later (1994 July) ROSAT PSPC observation of OY Car that allows
us to put constraints on the quiescent X-ray spectrum. We find that while there
is little to choose between OY Car and its fellow high inclination systems with
regard to the temperature of the emitting gas and the emission measure, we have
difficulties reconciling the column density found from our X-ray observation
with the column found in HST UV observations by Horne et al. (1994). The
obvious option is to invoke time variability.Comment: 16 pages, 14 figures, accepted for publication in MNRA
N=2 Gauge Theories: Congruence Subgroups, Coset Graphs and Modular Surfaces
We establish a correspondence between generalized quiver gauge theories in
four dimensions and congruence subgroups of the modular group, hinging upon the
trivalent graphs which arise in both. The gauge theories and the graphs are
enumerated and their numbers are compared. The correspondence is particularly
striking for genus zero torsion-free congruence subgroups as exemplified by
those which arise in Moonshine. We analyze in detail the case of index 24,
where modular elliptic K3 surfaces emerge: here, the elliptic j-invariants can
be recast as dessins d'enfant which dictate the Seiberg-Witten curves.Comment: 42+1 pages, 5 figures; various helpful comments incorporate
Effects of Large-Scale Convection on p-mode Frequencies
We describe an approach for finding the eigenfrequencies of solar acoustic
modes (p modes) in a convective envelope in the WKB limit. This approximation
restricts us to examining the effects of fluid motions which are large compared
to the mode wavelength, but allows us to treat the three-dimensional mode as a
localized ray. The method of adiabatic switching is then used to investigate
the frequency shifts resulting from simple perturbations to a polytropic model
of the convection zone as well as from two basic models of a convective cell.
We find that although solely depth-dependent perturbations can give frequency
shifts which are first order in the strength of the perturbation, models of
convective cells generate downward frequency shifts which are second order in
the perturbation strength. These results may have implications for resolving
the differences between eigenfrequencies derived from solar models and those
found from helioseismic observations.Comment: 27 pages + 6 figures; accepted for publication in Ap
Implementation of a Goal-Based Systems Engineering Process Using the Systems Modeling Language (SysML)
Building upon the purpose, theoretical approach, and use of a Goal-Function Tree (GFT) being presented by Dr. Stephen B. Johnson, described in a related Infotech 2013 ISHM abstract titled "Goal-Function Tree Modeling for Systems Engineering and Fault Management", this paper will describe the core framework used to implement the GFTbased systems engineering process using the Systems Modeling Language (SysML). These two papers are ideally accepted and presented together in the same Infotech session. Statement of problem: SysML, as a tool, is currently not capable of implementing the theoretical approach described within the "Goal-Function Tree Modeling for Systems Engineering and Fault Management" paper cited above. More generally, SysML's current capabilities to model functional decompositions in the rigorous manner required in the GFT approach are limited. The GFT is a new Model-Based Systems Engineering (MBSE) approach to the development of goals and requirements, functions, and its linkage to design. As a growing standard for systems engineering, it is important to develop methods to implement GFT in SysML. Proposed Method of Solution: Many of the central concepts of the SysML language are needed to implement a GFT for large complex systems. In the implementation of those central concepts, the following will be described in detail: changes to the nominal SysML process, model view definitions and examples, diagram definitions and examples, and detailed SysML construct and stereotype definitions
Cis-regulatory elements of the mitotic regulator, string/Cdc25
Mitosis in most Drosophila cells is triggered by brief bursts of transcription of string (stg), a Cdc25-type phosphatase that activates the mitotic kinase, Cdk1 (Cdc2). To understand how string transcription is regulated, we analyzed the expression of string-lacZ reporter genes covering approximately 40 kb of the string locus. We also tested protein coding fragments of the string locus of 6 kb to 31.6 kb for their ability to complement loss of string function in embryos and imaginal discs. A plethora of cis-acting elements spread over >30 kb control string transcription in different cells and tissue types. Regulatory elements specific to subsets of epidermal cells, mesoderm, trachea and nurse cells were identified, but the majority of the string locus appears to be devoted to controlling cell proliferation during neurogenesis. Consistent with this, compact promotor-proximal sequences are sufficient for string function during imaginal disc growth, but additional distal elements are required for the development of neural structures in the eye, wing, leg and notum. We suggest that, during evolution, cell-type-specific control elements were acquired by a simple growth-regulated promoter as a means of coordinating cell division with developmental processes, particularly neurogenesis.Dara A. Lehman; Briony Patterson, Laura A. Johnston; Tracy Balzer; Jessica S. Britton; Robert Saint and Bruce A. Edga
Unit cell of graphene on Ru(0001): a 25 x 25 supercell with 1250 carbon atoms
The structure of a single layer of graphene on Ru(0001) has been studied
using surface x-ray diffraction. A surprising superstructure has been
determined, whereby 25 x 25 graphene unit cells lie on 23 x 23 unit cells of
Ru. Each supercell contains 2 x 2 crystallographically inequivalent subcells
caused by corrugation. Strong intensity oscillations in the superstructure rods
demonstrate that the Ru substrate is also significantly corrugated down to
several monolayers, and that the bonding between graphene and Ru is strong and
cannot be caused by van der Waals bonds. Charge transfer from the Ru substrate
to the graphene expands and weakens the C-C bonds, which helps accommodate the
in-plane tensile stress. The elucidation of this superstructure provides
important information in the potential application of graphene as a template
for nanocluster arrays.Comment: 9 pages, 3 figures, paper submitted to peer reviewed journa
Colouring random graphs and maximising local diversity
We study a variation of the graph colouring problem on random graphs of
finite average connectivity. Given the number of colours, we aim to maximise
the number of different colours at neighbouring vertices (i.e. one edge
distance) of any vertex. Two efficient algorithms, belief propagation and
Walksat are adapted to carry out this task. We present experimental results
based on two types of random graphs for different system sizes and identify the
critical value of the connectivity for the algorithms to find a perfect
solution. The problem and the suggested algorithms have practical relevance
since various applications, such as distributed storage, can be mapped onto
this problem.Comment: 10 pages, 10 figure
An XMM-Newton observation of the nova-like variable UX UMa: spatially and spectrally resolved two-component X-ray emission
In the optical and ultraviolet regions of the electromagnetic spectrum, UX
Ursae Majoris is a deeply eclipsing cataclysmic variable. However, no soft
X-ray eclipse was detected in ROSAT observations. We have obtained a 38 ksec
XMM-Newton observation to further constrain the origin of the X-rays. The
combination of spectral and timing information allows us to identify two
components in the X-ray emission of the system. The soft component, dominant
below photon energies of 2 keV, can be fitted with a multi-temperature plasma
model and is uneclipsed. The hard component, dominant above 3 keV, can be
fitted with a kT ~ 5 keV plasma model and appears to be deeply eclipsed. We
suggest that the most likely source of the hard X-ray emission in UX UMa, and
other systems in high mass transfer states, is the boundary layer.Comment: To appear in MNRAS Letter
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