1,965 research outputs found
Using SPSS to Analyze Complex Survey Data: A Primer
An introduction to using SPSS to analyze complex survey data is given. Key features of complex survey design are described briefly, including stratification, clustering, multiple stages, and weights. Then, annotated SPSS syntax for complex survey data analysis is presented to demonstrate the step-by-step process using real complex samples data
The Non-Parametric Difference Score: A Workable Solution for Analyzing Two-Wave Change When The Measures Themselves Change Across Waves
The non-parametric difference score is introduced. It is a workable solution to the problem of analyzing change over two waves (i.e., a pretest-posttest design) when the measures themselves vary over time. An example highlighting the solutionâs implementation is provided, as is a discussion of the solutionâs assumptions, strengths, and limitations
JMASM 32: Multiple Imputation of Missing Multilevel, Longitudinal Data: A Case When Practical Considerations Trump Best Practices?
A pedagogical tool is presented for applied researchers dealing with incomplete multilevel, longitudinal data. It explains why such data pose special challenges regarding missingness. Syntax created to perform a multiply-imputed growth modeling procedure in Stata Version 11 (StataCorp, 2009) is also described
A Glossary on Building Longitudinal, Population-Based Data Linkages to Explore Childrenâs Developmental Trajectories
Population-based, person-specific, longitudinal child and youth health and developmental data linkages involve connecting combinations of specially-collected data and administrative data for longitudinal population research purposes. This glossary provides definitions of key terms and concepts related to their theoretical basis, research infrastructure, research methodology, statistical analysis, and knowledge translation
Chemical Compositions of Red Giant Stars in Old Large Magellanic Cloud Globular Clusters
We have observed ten red giant stars in four old Large Magellanic Cloud
globular clusters with the high-resolution spectrograph MIKE on the Magellan
Landon Clay 6.5-m telescope. The stars in our sample have up to 20 elemental
abundance determinations for the alpha-, iron-peak, and neutron-capture element
groups. We have also derived abundances for the light odd-Z elements Na and Al.
We find NGC 2005 and NGC 2019 to be more metal-rich than previous estimates
from the Ca II triplet, and we derive [Fe/H] values closer to those obtained
from the slope of the red giant branch. However, we confirm previous
determinations for Hodge 11 and NGC 1898 to within 0.2 dex. The LMC cluster
[Mg/Fe] and [Si/Fe] ratios are comparable to the values observed in old
Galactic globular cluster stars, as are the abundances [Y/Fe], [Ba/Fe], and
[Eu/Fe]. The LMC clusters do not share the low-Y behavior observed in some
dwarf spheroidal galaxies. [Ca/Fe], [Ti/Fe], and [V/Fe] in the LMC, however,
are significantly lower than what is seen in the Galactic globular cluster
system. Neither does the behavior of [Cu/Fe] as a function of [Fe/H] in our LMC
clusters match the trend seen in the Galaxy, staying instead at a constant
value of ~0.8. Because not all [alpha/Fe] ratios are suppressed, these
abundance ratios cannot be attributed solely to the injection of Type Ia SNe
material, and instead reflect the differences in star formation history of the
LMC vs. the Milky Way. We conclude that many of the abundances in the LMC
globular clusters we observed are distinct from those observed in the Milky
Way, and these differences are intrinsic to the stars in those systems.Comment: To be published in ApJ, 21 pages, 12 figures. Tables 2 (equivalent
widths) and 3 (hyperfine splitting information) included separatel
Meta-analysis of genome-wide association studies from the CHARGE consortium identifies common variants associated with carotid intima media thickness and plaque
Carotid intima media thickness (cIMT) and plaque determined by ultrasonography are established measures of subclinical atherosclerosis that each predicts future cardiovascular disease events. We conducted a meta-analysis of genome-wide association data in 31,211 participants of European ancestry from nine large studies in the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. We then sought additional evidence to support our findings among 11,273 individuals using data from seven additional studies. In the combined meta-analysis, we identified three genomic regions associated with common carotid intima media thickness and two different regions associated with the presence of carotid plaque (P < 5 Ă 10 -8). The associated SNPs mapped in or near genes related to cellular signaling, lipid metabolism and blood pressure homeostasis, and two of the regions were associated with coronary artery disease (P < 0.006) in the Coronary Artery Disease Genome-Wide Replication and Meta-Analysis (CARDIoGRAM) consortium. Our findings may provide new insight into pathways leading to subclinical atherosclerosis and subsequent cardiovascular events
Ethical issues, research and vulnerability : gaining the views of children and young people in residential care
Children and young people in residential care are some of the most vulnerable in our society. They may have experienced violence and physical, sexual or emotional abuse. They may be involved in offending or the misuse of drugs and alcohol. They are separated from their families and have to cope with living in a group situation with other young people and staff members. Children and young people in residential care also possess strengths, competencies and resilience. We have much to learn from their experiences and perspectives, both generally and surrounding their time in care. This paper will address the ethical issues which arise from gaining the views of children and young people in residential care, drawing on the experience of carrying out three studies in particular (Kendrick et al. 2004, The development of a residential unit working with sexually aggressive young men. In: H.G. Eriksson and T. Tjelflaat, eds. Residential care: horizons for the new century. Aldershot: Ashgate, 38-55; Docherty et al. 2006, Designing with care: interior design and residential child care. Farm7 and SIRCC. http://www.sircc.strath.ac.uk/publications/Designing_with_Care.pdf; Steckley, L. and Kendrick, A., 2005. Physical restraint in residential child care: the experiences of young people and residential workers. Childhoods 2005: Children and Youth in Emerging and Transforming Societies, University of Oslo, Norway, 29 June-3 July 2005, Steckley and Kendrick 2007, Young people's experiences of physical restraint in residential care: subtlety and complexity in policy and practice. In: M. Nunno, L. Bullard and D. Day, eds. For our own safety: examining the safety of high-risk interventions for children and young people. Washington, DC: Child Welfare League of America, forthcoming). The paper will discuss: information, consent and choice about involvement in the research; confidentiality, privacy and safety. It will also explore some of the more complex issues of ethical good practice which arise from researching children in their own living space. The negotiation of children's time and space must be approached carefully, with consideration of their rights and wishes. Sensitivity to children and young people's priorities and preoccupations must be paramount
Morphology of the earliest reconstructable tetrapod Parmastega aelidae.
The known diversity of tetrapods of the Devonian period has increased markedly in recent decades, but their fossil record consists mostly of tantalizing fragments1-15. The framework for interpreting the morphology and palaeobiology of Devonian tetrapods is dominated by the near complete fossils of Ichthyostega and Acanthostega; the less complete, but partly reconstructable, Ventastega and Tulerpeton have supporting roles2,4,16-34. All four of these genera date to the late Famennian age (about 365-359 million years ago)-they are 10 million years younger than the earliest known tetrapod fragments5,10, and nearly 30 million years younger than the oldest known tetrapod footprints35. Here we describe Parmastega aelidae gen. et sp. nov., a tetrapod from Russia dated to the earliest Famennian age (about 372 million years ago), represented by three-dimensional material that enables the reconstruction of the skull and shoulder girdle. The raised orbits, lateral line canals and weakly ossified postcranial skeleton of P. aelidae suggest a largely aquatic, surface-cruising animal. In Bayesian and parsimony-based phylogenetic analyses, the majority of trees place Parmastega as a sister group to all other tetrapods
Rapid automatic segmentation of abnormal tissue in late gadolinium enhancement cardiovascular magnetic resonance images for improved management of long-standing persistent atrial fibrillation
Background: Atrial fibrillation (AF) is the most common heart rhythm disorder. In order for late Gd enhancement cardiovascular magnetic resonance (LGE CMR) to ameliorate the AF management, the ready availability of the accurate enhancement segmentation is required. However, the computer-aided segmentation of enhancement in LGE CMR of AF is still an open question. Additionally, the number of centres that have reported successful application of LGE CMR to guide clinical AF strategies remains low, while the debate on LGE CMRâs diagnostic ability for AF still holds. The aim of this study is to propose a method that reliably distinguishes enhanced (abnormal) from non-enhanced (healthy) tissue within the left atrial wall of (pre-ablation and 3 months post-ablation) LGE CMR data-sets from long-standing persistent AF patients studied at our centre.
Methods: Enhancement segmentation was achieved by employing thresholds benchmarked against the statistics of the whole left atrial blood-pool (LABP). The test-set cross-validation mechanism was applied to determine the input feature representation and algorithm that best predict enhancement threshold levels.
Results: Global normalized intensity threshold levels T PRE = 1 1/4 and T POST = 1 5/8 were found to segment enhancement in data-sets acquired pre-ablation and at 3 months post-ablation, respectively. The segmentation results were corroborated by using visual inspection of LGE CMR brightness levels and one endocardial bipolar voltage map. The measured extent of pre-ablation fibrosis fell within the normal range for the specific arrhythmia phenotype. 3D volume renderings of segmented post-ablation enhancement emulated the expected ablation lesion patterns. By comparing our technique with other related approaches that proposed different threshold levels (although they also relied on reference regions from within the LABP) for segmenting enhancement in LGE CMR data-sets of AF patients, we illustrated that the cut-off levels employed by other centres may not be usable for clinical studies performed in our centre.
Conclusions: The proposed technique has great potential for successful employment in the AF management within our centre. It provides a highly desirable validation of the LGE CMR technique for AF studies. Inter-centre differences in the CMR acquisition protocol and image analysis strategy inevitably impede the selection of a universally optimal algorithm for segmentation of enhancement in AF studies
Recurrent Coding Sequence Variation Explains only A Small Fraction of the Genetic Architecture of Colorectal Cancer
Whilst common genetic variation in many non-coding genomic regulatory regions are known to impart risk of colorectal cancer (CRC), much of the heritability of CRC remains unexplained. To examine the role of recurrent coding sequence variation in CRC aetiology, we genotyped 12,638 CRCs cases and 29,045 controls from six European populations. Single-variant analysis identified a coding variant (rs3184504) in SH2B3 (12q24) associated with CRC risk (OR = 1.08, P = 3.9 Ă 10-7), and novel damaging coding variants in 3 genes previously tagged by GWAS efforts; rs16888728 (8q24) in UTP23 (OR = 1.15, P = 1.4 Ă 10-7); rs6580742 and rs12303082 (12q13) in FAM186A (OR = 1.11, P = 1.2 Ă 10-
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