734 research outputs found
Lean manufacturing and Toyota Production System terminology applied to the procurement of vascular stents in interventional radiology
Linear, Deterministic, and Order-Invariant Initialization Methods for the K-Means Clustering Algorithm
Over the past five decades, k-means has become the clustering algorithm of
choice in many application domains primarily due to its simplicity, time/space
efficiency, and invariance to the ordering of the data points. Unfortunately,
the algorithm's sensitivity to the initial selection of the cluster centers
remains to be its most serious drawback. Numerous initialization methods have
been proposed to address this drawback. Many of these methods, however, have
time complexity superlinear in the number of data points, which makes them
impractical for large data sets. On the other hand, linear methods are often
random and/or sensitive to the ordering of the data points. These methods are
generally unreliable in that the quality of their results is unpredictable.
Therefore, it is common practice to perform multiple runs of such methods and
take the output of the run that produces the best results. Such a practice,
however, greatly increases the computational requirements of the otherwise
highly efficient k-means algorithm. In this chapter, we investigate the
empirical performance of six linear, deterministic (non-random), and
order-invariant k-means initialization methods on a large and diverse
collection of data sets from the UCI Machine Learning Repository. The results
demonstrate that two relatively unknown hierarchical initialization methods due
to Su and Dy outperform the remaining four methods with respect to two
objective effectiveness criteria. In addition, a recent method due to Erisoglu
et al. performs surprisingly poorly.Comment: 21 pages, 2 figures, 5 tables, Partitional Clustering Algorithms
(Springer, 2014). arXiv admin note: substantial text overlap with
arXiv:1304.7465, arXiv:1209.196
Factors Influencing Receipt of Iron Supplementation by Young Children and their Mothers in Rural India: Local and National Cross-Sectional Studies
<p>Abstract</p> <p>Background</p> <p>In India, 55% of women and 69.5% of preschool children are anaemic despite national policies recommending routine iron supplementation. Understanding factors associated with receipt of iron in the field could help optimise implementation of anaemia control policies. Thus, we undertook 1) a cross-sectional study to evaluate iron supplementation to children (and mothers) in rural Karnataka, India, and 2) an analysis of all-India rural data from the National Family Health Study 2005-6 (NFHS-3).</p> <p>Methods</p> <p>All children aged 12-23 months and their mothers served by 6 of 8 randomly selected sub-centres managed by 2 rural Primary Health Centres of rural Karnataka were eligible for the Karnataka Study, conducted between August and October 2008. Socioeconomic and demographic data, access to health services and iron receipt were recorded. Secondly, NFHS-3 rural data were analysed. For both studies, logistic regression was used to evaluate factors associated with receipt of iron.</p> <p>Results</p> <p>The Karnataka Study recruited 405 children and 377 of their mothers. 41.5% of children had received iron, and 11.5% received iron through the public system. By multiple logistic regression, factors associated with children's receipt of iron included: wealth (Odds Ratio (OR) 2.63 [95% CI 1.11, 6.24] for top vs bottom wealth quintile), male sex (OR 2.45 [1.47, 4.10]), mother receiving postnatal iron (OR 2.31 [1.25, 4.28]), mother having undergone antenatal blood test (OR 2.10 [1.09, 4.03]); Muslim religion (OR 0.02 [0.00, 0.27]), attendance at Anganwadi centre (OR 0.23 [0.11, 0.49]), fully vaccinated (OR 0.33 [0.15, 0.75]), or children of mothers with more antenatal health visits (8-9 visits OR 0.25 [0.11, 0.55]) were less likely to receive iron. Nationally, 3.7% of rural children were receiving iron; this was associated with wealth (OR 1.12 [1.02, 1.23] per quintile), maternal education (compared with no education: completed secondary education OR 2.15 [1.17, 3.97], maternal antenatal iron (2.24 [1.56, 3.22]), and child attending an Anganwadi (OR 1.47 [1.20, 1.80]).</p> <p>Conclusion</p> <p>In rural India, public distribution of iron to children is inadequate and disparities exist. Measures to optimize receipt of government supplied iron to all children regardless of wealth and ethnic background could help alleviate anaemia in this population.</p
Comparison of positive surgical margin rates in high risk prostate cancer: open versus minimally invasive radical prostatectomy
Independent policy learning: Contextual diffusion of active labour market policies
This chapter analyses in which ways diffusion based on interdependent policy learning explains the spread of active labour market policies (ALMP) in the OECD countries. By applying error correction models using multiplicative spatial Prais-Winsten regressions for analyzing the diffusion of ALMPs in 22 OECD countries from 1991â2013, we find evidence of governments adapting labour market policy strategies that have proven successful, that is, perform well in increasing labour market participation in other countries. However, interdependent learning is conditional on the institutional framework: policymakers rather learn from the experience of other countries in the same welfare regime. Even more importantly, the results bear witness to the importance of the European Employment Strategy (EES) as an international coordination framework facilitating policy learning
Context, mechanisms and outcomes in end of life care for people with advanced dementia
yesBackground: The majority of people with dementia in the UK die in care homes. The quality of end of life care in
these environments is often suboptimal. The aim of the present study was to explore the context, mechanisms and
outcomes for providing good palliative care to people with advanced dementia residing in UK care homes from
the perspective of health and social care providers.
Method: The design of the study was qualitative which involved purposive sampling of health care professionals to
undertake interactive interviews within a realist framework. Interviews were completed between September 2012
and October 2013 and were thematically analysed and then conceptualised according to context, mechanisms and
outcomes. The settings were private care homes and services provided by the National Health Service including
memory clinics, mental health and commissioning services in London, United Kingdom. The participants included
14 health and social care professionals including health care assistants, care home managers, commissioners for
older adultsâ services and nursing staff.
Results: Good palliative care for people with advanced dementia is underpinned by the prioritisation of
psychosocial and spiritual care, developing relationships with family carers, addressing physical needs including
symptom management and continuous, integrated care provided by a multidisciplinary team. Contextual factors
that detract from good end of life care included: an emphasis on financial efficiency over person-centred care; a
complex health and social care system, societal and family attitudes towards staff; staff training and experience,
governance and bureaucratisation; complexity of dementia; advance care planning and staff characteristics.
Mechanisms that influence the quality of end of life care include: level of health care professionalsâ confidence,
family uncertainty about end of life care, resources for improving end of life care and supporting families, and
uncertainty about whether dementia specific palliative care is required.
Conclusions: Contextual factors regarding the care home environment may be obdurate and tend to negatively
impact on the quality of end of life dementia care. Local level mechanisms may be more amenable to
improvement. However, systemic changes to the care home environment are necessary to promote consistent,
equitable and sustainable high quality end of life dementia care across the UK care home secto
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Hyperpolarized<sup>13</sup>C-Pyruvate Metabolism as a Surrogate for Tumor Grade and Poor Outcome in Renal Cell CarcinomaâA Proof of Principle Study
Differentiating aggressive clear cell renal cell carcinoma (ccRCC) from indolent lesions is challenging using conventional imaging. This work prospectively compared the metabolic imaging phenotype of renal tumors using carbon-13 MRI following injection of hyperpolarized [1-13C]pyruvate (HP-13C-MRI) and validated these findings with histopathology. Nine patients with treatment-naĂŻve renal tumors (6 ccRCCs, 1 liposarcoma, 1 pheochromocytoma, 1 oncocytoma) underwent pre-operative HP-13C-MRI and conventional proton (1H) MRI. Multi-regional tissue samples were collected using patient-specific 3D-printed tumor molds for spatial registration between imaging and molecular analysis. The apparent exchange rate constant (kPL) between 13C-pyruvate and 13C-lactate was calculated. Immunohistochemistry for the pyruvate transporter (MCT1) from 44 multi-regional samples, as well as associations between MCT1 expression and outcome in the TCGA-KIRC dataset, were investigated. Increasing kPL in ccRCC was correlated with increasing overall tumor grade (Ï = 0.92, p = 0.009) and MCT1 expression (r = 0.89, p = 0.016), with similar results acquired from the multi-regional analysis. Conventional 1H-MRI parameters did not discriminate tumor grades. The correlation between MCT1 and ccRCC grade was confirmed within a TCGA dataset (p < 0.001), where MCT1 expression was a predictor of overall and disease-free survival. In conclusion, metabolic imaging using HP-13C-MRI differentiates tumor aggressiveness in ccRCC and correlates with the expression of MCT1, a predictor of survival. HP-13C-MRI may non-invasively characterize metabolic phenotypes within renal cancer.</jats:p
Photodisintegration of He into p+t
The two-body photodisintegration of He into a proton and a triton has
been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at Jefferson
Laboratory. Real photons produced with the Hall-B bremsstrahlung-tagging system
in the energy range from 0.35 to 1.55 GeV were incident on a liquid He
target. This is the first measurement of the photodisintegration of He
above 0.4 GeV. The differential cross sections for the He
reaction have been measured as a function of photon-beam energy and
proton-scattering angle, and are compared with the latest model calculations by
J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the
calculations that include three-body mechanisms, thus confirming their
importance. These results reinforce the conclusion of our previous study of the
three-body breakup of He that demonstrated the great importance of
three-body mechanisms in the energy region 0.5-0.8 GeV .Comment: 13 pages submitted in one tgz file containing 2 tex file and 22
postscrip figure
Exclusive electroproduction on the proton at CLAS
The reaction has been measured, using the 5.754
GeV electron beam of Jefferson Lab and the CLAS detector. This represents the
largest ever set of data for this reaction in the valence region. Integrated
and differential cross sections are presented. The , and
dependences of the cross section are compared to theoretical calculations based
on -channel meson-exchange Regge theory on the one hand and on quark handbag
diagrams related to Generalized Parton Distributions (GPDs) on the other hand.
The Regge approach can describe at the 30% level most of the features
of the present data while the two GPD calculations that are presented in this
article which succesfully reproduce the high energy data strongly underestimate
the present data. The question is then raised whether this discrepancy
originates from an incomplete or inexact way of modelling the GPDs or the
associated hard scattering amplitude or whether the GPD formalism is simply
inapplicable in this region due to higher-twists contributions, incalculable at
present.Comment: 29 pages, 29 figure
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