7,376 research outputs found
Shuttle Integration Status
As the Space Shuttle nears its first flight, the systems activity is changing its emphasis to concentrate on certification of the flight system and potential growth into the future. In this paper I would like to explain how we have approached the certification of the Shuttle system and then later describe recent activities which will enhance the capability of the Shuttle during the operational time period
Predicting Dementia in Cerebral Small Vessel Disease Using an Automatic Diffusion Tensor Image Segmentation Technique.
Background and Purpose- Cerebral small vessel disease (SVD) is the most common cause of vascular cognitive impairment, with a significant proportion of cases going on to develop dementia. We explore the extent to which diffusion tensor image segmentation technique (DSEG; which characterizes microstructural damage across the cerebrum) predicts both degree of cognitive decline and conversion to dementia, and hence may provide a useful prognostic procedure. Methods- Ninety-nine SVD patients (aged 43-89 years) underwent annual magnetic resonance imaging scanning (for 3 years) and cognitive assessment (for 5 years). DSEG-θ was used as a whole-cerebrum measure of SVD severity. Dementia diagnosis was based Diagnostic and Statistical Manual of Mental Disorders V criteria. Cox regression identified which DSEG measures and vascular risk factors were related to increased risk of dementia. Linear discriminant analysis was used to classify groups of stable versus subsequent dementia diagnosis individuals. Results- DSEG-θ was significantly related to decline in executive function and global cognition (P<0.001). Eighteen (18.2%) patients converted to dementia. Baseline DSEG-θ predicted dementia with a balanced classification rate=75.95% and area under the receiver operating characteristic curve=0.839. The best classification model included baseline DSEG-θ, change in DSEG-θ, age, sex, and premorbid intelligence quotient (balanced classification rate of 79.65%; area under the receiver operating characteristic curve=0.903). Conclusions- DSEG is a fully automatic technique that provides an accurate method for assessing brain microstructural damage in SVD from a single imaging modality (diffusion tensor imaging). DSEG-θ is an important tool in identifying SVD patients at increased risk of developing dementia and has potential as a clinical marker of SVD severity
An approach for solving the boundary free edge difficulties in SPH modelling: application to a viscous accretion disc in close binaries
In this work, we propose a SPH interpolating Kernel reformulation suitable
also to treat free edge boundaries in the computational domain. Application to
both inviscid and viscous stationary low compressibility accretion disc models
in Close Binaries (CB) are shown. The investigation carried out in this paper
is a consequence of the fact that a low compressibility modelling is crucial to
check numerical reliability.
Results show that physical viscosity supports a well-bound accretion disc
formation, despite the low gas compressibility, when a Gaussian-derived Kernel
(from the Error Function) is assumed, in extended particle range - whose Half
Width at Half Maximum (HWHM) is fixed to a constant value - without any
spatial restrictions on its radial interaction (hereinafter GASPHER). At the
same time, GASPHER ensures adequate particle interpolations at the boundary
free edges. Both SPH and adaptive SPH (hereinafter ASPH) methods lack accuracy
if there are not constraints on the boundary conditions, in particular at the
edge of the particle envelope: Free Edge (FE) conditions. In SPH, an
inefficient particle interpolation involves a few neighbour particles; instead,
in the second case, non-physical effects involve both the boundary layer
particles themselves and the radial transport.
Either in a regime where FE conditions involve the computational domain, or
in a viscous fluid dynamics, or both, a GASPHER scheme can be rightly adopted
in such troublesome physical regimes. Despite the applied low compressibiity
condition, viscous GASPHER model shows clear spiral pattern profiles
demonstrating the better quality of results compared to SPH viscous ones.
Moreover a successful comparison of results concerning GASPHER 1D inviscid
shock tube with analytical solution is also reported.Comment: 18 pages, 12 figure
Participation in physical play and leisure : developing a theory- and evidence-based intervention for children with motor impairments
Peer reviewedPublisher PD
Genetically predicted complement component 4A expression: effects on memory function and middle temporal lobe activation
Background The longstanding association between the major histocompatibility complex (MHC) locus and schizophrenia (SZ) risk has recently been accounted for, partially, by structural variation at the complement component 4 (C4) gene. This structural variation generates varying levels of C4 RNA expression, and genetic information from the MHC region can now be used to predict C4 RNA expression in the brain. Increased predicted C4A RNA expression is associated with the risk of SZ, and C4 is reported to influence synaptic pruning in animal models. Methods Based on our previous studies associating MHC SZ risk variants with poorer memory performance, we tested whether increased predicted C4A RNA expression was associated with reduced memory function in a large (n = 1238) dataset of psychosis cases and healthy participants, and with altered task-dependent cortical activation in a subset of these samples. Results We observed that increased predicted C4A RNA expression predicted poorer performance on measures of memory recall (p = 0.016, corrected). Furthermore, in healthy participants, we found that increased predicted C4A RNA expression was associated with a pattern of reduced cortical activity in middle temporal cortex during a measure of visual processing (p < 0.05, corrected). Conclusions These data suggest that the effects of C4 on cognition were observable at both a cortical and behavioural level, and may represent one mechanism by which illness risk is mediated. As such, deficits in learning and memory may represent a therapeutic target for new molecular developments aimed at altering C4’s developmental role
Parsec-scale Properties of Brightest Cluster Galaxies
We present new VLBI observations at 5 GHz of a complete sample of Brightest
Cluster Galaxies (BCGs) in nearby Abell Clusters (distance class <3). Combined
with data from the literature, this provides parsec-scale information for 34
BCGs. Our analysis of their parsec scale radio emission and cluster X-ray
properties shows a possible dichotomy between BCGs in cool core clusters and
those in non cool core clusters. Among resolved sources, those in cool core
clusters tend to have two-sided parsec-scale jets, while those in less relaxed
clusters have predominantly one-sided parsec-scale jets. We suggest that this
difference could be the result of interplay between the jets and the
surrounding medium. The one-sided structure in non cool core clusters could be
due to Doppler boosting effects in relativistic, intrinsically symmetric jets;
two-sided morphology in cool core clusters is likely related to the presence of
heavy and mildly relativistic jets slowed down on the parsec-scale. Evidence of
recurrent activity are also found in BCGs in cool core clusters.Comment: 20 pages, 10 figures, accepted for publication in A&
O2‐08‐05: Neuronal Injury and Degeneration Evaluated with Imaging and CSF Biomarkers in Autosomal Dominant Alzheimer’s Disease: Results from the Dian Study
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152556/1/alzjjalz201606440.pd
The American Association for the Surgery of Trauma renal injury grading scale: Implications of the 2018 revisions for injury reclassification and predicting bleeding interventions.
BackgroundIn 2018, the American Association for the Surgery of Trauma (AAST) published revisions to the renal injury grading system to reflect the increased reliance on computed tomography scans and non-operative management of high-grade renal trauma (HGRT). We aimed to evaluate how these revisions will change the grading of HGRT and if it outperforms the original 1989 grading in predicting bleeding control interventions.MethodsData on HGRT were collected from 14 Level-1 trauma centers from 2014 to 2017. Patients with initial computed tomography scans were included. Two radiologists reviewed the scans to regrade the injuries according to the 1989 and 2018 AAST grading systems. Descriptive statistics were used to assess grade reclassifications. Mixed-effect multivariable logistic regression was used to measure the predictive ability of each grading system. The areas under the curves were compared.ResultsOf the 322 injuries included, 27.0% were upgraded, 3.4% were downgraded, and 69.5% remained unchanged. Of the injuries graded as III or lower using the 1989 AAST, 33.5% were upgraded to grade IV using the 2018 AAST. Of the grade V injuries, 58.8% were downgraded using the 2018 AAST. There was no statistically significant difference in the overall areas under the curves between the 2018 and 1989 AAST grading system for predicting bleeding interventions (0.72 vs. 0.68, p = 0.34).ConclusionAbout one third of the injuries previously classified as grade III will be upgraded to grade IV using the 2018 AAST, which adds to the heterogeneity of grade IV injuries. Although the 2018 AAST grading provides more anatomic details on injury patterns and includes important radiologic findings, it did not outperform the 1989 AAST grading in predicting bleeding interventions.Level of evidencePrognostic and Epidemiological Study, level III
Detailed Investigation of the Role of Common and Low-Frequency WFS1 Variants in Type 2 Diabetes Risk
OBJECTIVE: Wolfram syndrome 1 (WFS1) single nucleotide polymorphisms (SNPs) are associated with risk of type 2 diabetes. In this study we aimed to refine this association and investigate the role of low-frequency WFS1 variants in type 2 diabetes risk. RESEARCH DESIGN AND METHODS: For fine-mapping, we sequenced WFS1 exons, splice junctions, and conserved noncoding sequences in samples from 24 type 2 diabetic case and 68 control subjects, selected tagging SNPs, and genotyped these in 959 U.K. type 2 diabetic case and 1,386 control subjects. The same genomic regions were sequenced in samples from 1,235 type 2 diabetic case and 1,668 control subjects to compare the frequency of rarer variants between case and control subjects. RESULTS: Of 31 tagging SNPs, the strongest associated was the previously untested 3' untranslated region rs1046320 (P = 0.008); odds ratio 0.84 and P = 6.59 x 10(-7) on further replication in 3,753 case and 4,198 control subjects. High correlation between rs1046320 and the original strongest SNP (rs10010131) (r2 = 0.92) meant that we could not differentiate between their effects in our samples. There was no difference in the cumulative frequency of 82 rare (minor allele frequency [MAF] 100,000) or studies in ethnically diverse populations. Low frequency variants in WFS1 are unlikely to have a large impact on type 2 diabetes risk in white U.K. populations, highlighting the complexities of undertaking association studies with low-frequency variants identified by resequencing
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