135 research outputs found
Optimizing protection for rear seat occupants: assessing booster performance with realistic belt geometry using the Hybrid III 6YO ATD
A series of sled tests was conducted to examine the performance of booster seats under belt geometries representing the range found in the rear seats of current vehicles. Twelve tests were performed with the standard 6YO Hybrid III ATD and 29 tests were performed with a modified version of the 6YO ATD. The modified dummy has a pelvis with more realistic shape and flesh stiffness, a gel abdomen with biomechanically-based stiffness characteristics, and a custom neoprene jacket. Shoulder belt upper anchorage was set at the FMVSS No. 213 belt anchorage location and 64 mm inboard and outboard from this location. Lap belt anchorage locations were chosen to span the range of lap belt angles permitted under FMVSS 210, using the FMVSS No. 213 belt anchorage locations and forward belt anchorage locations that produce a much steeper lap belt angle. Four booster seats that provide a range of static belt fit were used. The ATDs were positioned using either the standard FMVSS No. 213 seating procedure or an alternate UMTRI procedure that produces postures closer to those of similar-size children.
Kinematic results for the standard and modified dummies under the same test conditions were more similar than expected. The current version of the modified 6YO is less sensitive to lap belt geometry than the prototype version of the dummy. The seating procedure had a greater affect on kinematic results. The UMTRI seating procedure produced greater knee-head excursion differences and less forward torso rotation than the FMVSS No. 213 procedure.
Shifting the shoulder belt upper anchorage 128 mm laterally produced minimal variations in kinematics for a given booster seat/lap belt condition, likely because the belt-routing features of the booster seats limited the differences in static shoulder belt score to less than 10 mm. Moving the lap belt geometry from rearward (shallow angle) to forward (steep angle) produced less desirable kinematics with all booster seats tested. The forward position of the lap belt anchorage allows greater forward translation of the booster and ATD before the belt engages the pelvis. Steeper belt angles are associated with better lap belt fit for children sitting without boosters, so designing rear seat belts for children who sit with and without boosters may involve a performance tradeoff.National Highway Traffic Safety Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/90973/1/102860.pd
Comparing the CRABI-12 and CRABI-18 for Infant Child Restraint System Evaluation
Technical Report FinalA preliminary study was performed to consider how evaluation of rear-facing-only child restraints
might differ if the CRABI 18 month old crash test dummy was used instead of the CRABI 12 month
old. In comparison to child anthropometry data, the CRABI-18 does a better job in representing the
dimensions of children over 1 year old. Nineteen rear-facing-only child restraint systems (CRS) were
measured, and both test dummies were installed in the CRSs for static evaluation. The CRABI-12 fit
well in all the CRSs. Nine child restraints were too narrow for the CRABI-18 shoulders (including 7
CRSs for use with children at or over 18 kg [30 lb]), and 12 child restraints did not allow the
recommended 25 mm head clearance. In dynamic FMVSS No. 213 testing with 3 CRSs (Graco
Snugride30, Chicco KeyFit, and Evenflo Embrace), the measured response of both test dummies was
similar; both met all FMVSS No. 213 requirements.National Highway Traffic Safety Administrationhttps://deepblue.lib.umich.edu/bitstream/2027.42/154007/1/UMTRI-2013-5.pd
Modulation of renal oxygenation and perfusion in rat kidney monitored by quantitative diffusion and blood oxygen level dependent magnetic resonance imaging on a clinical 1.5T platform
ARRIVE Checklist. (DOCX 42 kb
Bisimulation as path type for guarded recursive types
In type theory, coinductive types are used to represent processes, and are
thus crucial for the formal verification of non-terminating reactive programs
in proof assistants based on type theory, such as Coq and Agda. Currently,
programming and reasoning about coinductive types is difficult for two reasons:
The need for recursive definitions to be productive, and the lack of
coincidence of the built-in identity types and the important notion of
bisimilarity.
Guarded recursion in the sense of Nakano has recently been suggested as a
possible approach to dealing with the problem of productivity, allowing this to
be encoded in types. Indeed, coinductive types can be encoded using a
combination of guarded recursion and universal quantification over clocks. This
paper studies the notion of bisimilarity for guarded recursive types in Ticked
Cubical Type Theory, an extension of Cubical Type Theory with guarded
recursion. We prove that, for any functor, an abstract, category theoretic
notion of bisimilarity for the final guarded coalgebra is equivalent (in the
sense of homotopy type theory) to path equality (the primitive notion of
equality in cubical type theory). As a worked example we study a guarded notion
of labelled transition systems, and show that, as a special case of the general
theorem, path equality coincides with an adaptation of the usual notion of
bisimulation for processes. In particular, this implies that guarded recursion
can be used to give simple equational reasoning proofs of bisimilarity. This
work should be seen as a step towards obtaining bisimilarity as path equality
for coinductive types using the encodings mentioned above
The Inheritance of Resistance Alleles in Multiple Sclerosis
Multiple sclerosis (MS) is a complex trait in which alleles at or near the class II loci HLA-DRB1 and HLA-DQB1 contribute significantly to genetic risk. HLA-DRB1*15 and HLA-DRB1*17-bearing haplotypes and interactions at the HLA-DRB1 locus increase risk of MS but it has taken large samples to identify resistance HLA-DRB1 alleles. In this investigation of 7,093 individuals from 1,432 MS families, we have assessed the validity, mode of inheritance, associated genotypes, and the interactions of HLA-DRB1 resistance alleles. HLA-DRB1*14-, HLA-DRB1*11-, HLA-DRB1*01-, and HLA-DRB1*10-bearing haplotypes are protective overall but they appear to operate by different mechanisms. The first type of resistance allele is characterised by HLA-DRB1*14 and HLA-DRB1*11. Each shows a multiplicative mode of inheritance indicating a broadly acting suppression of risk, but a different degree of protection. In contrast, a second type is exemplified by HLA-DRB1*10 and HLA-DRB1*01. These alleles are significantly protective when they interact specifically in trans with HLA-DRB1*15-bearing haplotypes. HLA-DRB1*01 and HLA-DRB1*10 do not interact with HLA-DRB1*17, implying that several mechanisms may be operative in major histocompatibility complexâassociated MS susceptibility, perhaps analogous to the resistance alleles. There are major practical implications for risk and for the exploration of mechanisms in animal models. Restriction of antigen presentation by HLA-DRB1*15 seems an improbably simple mechanism of major histocompatibility complexâassociated susceptibility
Developing hyperpolarized 13C spectroscopy and imaging for metabolic studies in the isolated perfused rat heart
Hyperpolarized 13C magnetic resonance is a powerful tool for the study of cardiac metabolism. In this work, we have implemented protocols for the real-time hyperpolarized 13C investigation of Langendorff-perfused rat hearts using both non-selective non-localized spectroscopy and fast spectroscopic imaging. Following [1-13C] pyruvate infusion, we observed both catabolic and anaplerotic metabolic processes resulting in a number of metabolites, including bicarbonate, carbon dioxide, lactate, alanine and aspartate. Employing fast spectroscopic imaging, we were able to observe regional variations in pyruvate perfusion as well as in lactate and bicarbonate production
Interpretability of radiomics models is improved when using feature group selection strategies for predicting molecular and clinical targets in clear-cell renal cell carcinoma: insights from the TRACERx Renal study
BACKGROUND: The aim of this work is to evaluate the performance of radiomics predictions for a range of molecular, genomic and clinical targets in patients with clear cell renal cell carcinoma (ccRCC) and demonstrate the impact of novel feature selection strategies and sub-segmentations on model interpretability. METHODS: Contrast-enhanced CT scans from the first 101 patients recruited to the TRACERx Renal Cancer study (NCT03226886) were used to derive radiomics classification models to predict 20 molecular, histopathology and clinical target variables. Manual 3D segmentation was used in conjunction with automatic sub-segmentation to generate radiomics features from the core, rim, high and low enhancing sub-regions, and the whole tumour. Comparisons were made between two classification model pipelines: a Conventional pipeline reflecting common radiomics practice, and a Proposed pipeline including two novel feature selection steps designed to improve model interpretability. For both pipelines nested cross-validation was used to estimate prediction performance and tune model hyper-parameters, and permutation testing was used to evaluate the statistical significance of the estimated performance measures. Further model robustness assessments were conducted by evaluating model variability across the cross-validation folds. RESULTS: Classification performance was significant (pââ0.1. Five of these targets (necrosis on histology, presence of renal vein invasion, overall histological stage, linear evolutionary subtype and loss of 9p21.3 somatic alteration marker) had AUROCâ>â0.8. Models derived using the Proposed pipeline contained fewer feature groups than the Conventional pipeline, leading to more straightforward model interpretations without loss of performance. Sub-segmentations lead to improved performance and/or improved interpretability when predicting the presence of sarcomatoid differentiation and tumour stage. CONCLUSIONS: Use of the Proposed pipeline, which includes the novel feature selection methods, leads to more interpretable models without compromising prediction performance. TRIAL REGISTRATION: NCT03226886 (TRACERx Renal
Demonstration of the reproducibility of free-breathing diffusion-weighted MRI and dynamic contrast enhanced MRI in children with solid tumours: a pilot study
Diffusionâ weighted imaging outside the brain: Consensus statement from an ISMRMâ sponsored workshop
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134160/1/jmri25196_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134160/2/jmri25196.pd
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