Modelling the foetus for pregnant occupant safety

Annual foetus mortality rates due to road traffic accidents are much higher than the infant mortality rates in motor vehicle crashes. The goal of this study is to generate a computational model of the unborn occupant (foetus) for crash protection research. The multibody foetus model is accommodated in the finite element uterus model of 'Expecting', the computational pregnant occupant model which tackles the complexity of a pregnant women's anatomy and incorporates pregnant female anthropometry. In particular, 38 weeks gestation level is focused upon since at this stage of pregnancy the foetus is at greatest risk during a crash due to the size increase of the abdomen resulting in a close proximity to the vehicle steering wheel and awkward routing of the seatbelt. This article explains in detail all stages of modelling the unborn occupant and the links to its environment, the uterus with a placenta and the computational female model

Development of a multi-body computational model of human head and neck

Experimental studies using human volunteers are limited to low acceleration impacts while whole cadavers, isolated cervical spine specimens, and impact dummies do not normally reflect the true human response. Computational modelling offers a cost effective and useful alternative to experimental methods to study the behaviour of the human head and neck and their response to impacts to gain insight into injury mechanisms. This article reports the approach used in the development of a detailed multi-body computational model that reproduces the head and cervical spine of an adult in the upright posture representing the natural lordosis of the neck with mid-sagittal symmetry. The model comprises simplified but accurate representations of the nine rigid bodies representing the head, seven cervical vertebrae of the neck, and the first thoracic vertebra, as well as the soft tissues, i.e. muscles, ligaments, and intervertebral discs. The rigid bodies are interconnected by non-linear viscoelastic intervertebral discs elements in flexion and extension, non-linear viscoelastic ligaments and supported through frictionless facet joints. Eighteen muscle groups and 69 individual muscle segments of the head and neck on each side of the body are also included in the model. Curving the muscle around the vertebrae and soft tissues of the neck during the motion of the neck is also modelled. Simulation is handled by the multi-body dynamic software MSC.visuaNastran4D. Muscle mechanics is handled by an external application, Virtual Muscle, in conjunction with MSC.visuaNastran4D that provides realistic muscle properties. Intervertebral discs are modelled as non-linear viscoelastic material in flexion and extension but represented by‘bushing elements’ inVisualNastran 4D, which allows stiffness and damping properties to be assigned to a joint with required number of degrees of freedom of the motion. Ligaments are modelled as non-linear viscoelastic spring–damper elements. As the model is constructed, the cervical spine motion segments are validated by comparing the segment response to published experimental data on the load–displacement behaviour for both small and large static loads. The response of the entire ligamentous cervical spine model to quasi-static flexion and extension loading is also compared to experimental data to validate the model before the effect of muscle stiffening is included. Moreover the moment-generating capacity of the neck muscle elements has been compared against in vivo experimental data. The main and coupled motions of the model segments are shown to be accurate and realistic, and the whole model is in good agreement with experimental findings fromactualhumancervical spine specimens. It has been shown that the model can predict the loads and deformations of the individual soft-tissue elements making the model suitable for injury analysis. The validation of the muscle elements shows the morphometric values, origins, and insertions selected to be reasonable. The muscles can be activated as required, providing a more realistic representation of the human head and neck. The curved musculature results in a more realistic representation of the change in muscle length during the head and neck motion

Dynamic verification of a multi-body computational model of human head and neck for frontal, lateral, and rear impacts

A multi-body computational model of the human head and neck was previously shown to be in good agreement with experimental findings from actual human cervical spine specimens. The model segments were tested in three directions of loading showing main and coupled motions to be accurate and realistic. The model’s ability to predict the dynamic response of the head and neck, when subjected to acceleration pulses representing frontal, lateral, and rear-end impacts, is verified using experimental data derived from sled acceleration tests with human volunteers for 15 g frontal and 7 g lateral impacts and from isolated cervical spine specimen tests for rear-end impacts. Response corridors based on sled acceleration tests with human volunteers for frontal and lateral impacts are used to evaluate the model and investigate the effect of muscle activation on the head– neck motion. Firstly, the impacts are simulated with both passive and active muscle behaviour. Secondly, the local loads in the soft-tissue elements during the frontal impact are analysed. For rear-end impact simulation experiments using ligamentous isolated cervical spine specimens are used to evaluate the model performance before investigating the effects of muscle tensioning. Good agreement with human volunteer response corridors resulting from frontal and lateral impacts, and isolated cervical spine specimen sled test rear-end impact experiments is demonstrated for the model, highlighting the important role the muscles of the neck play in the head–neck response to acceleration impacts. The model is shown to be able to predict the loads and deformations of the cervical spine components making it suitable for injury analysis

Computational pregnant occupant model, 'Expecting', for crash simulations

A computational model of the pregnant occupant, which is capable of simulating the dynamic response to acceleration impacts, is introduced. The occupant model represents a 5th percentile female at around the 38th week of pregnancy. A finite element uterus and multi-body fetus is integrated into an existing female model to incorporate pregnant female anthropometry. The complete model, ‘Expecting’, is used to simulate a range of frontal impacts of increasing severity from 15 km/h to 45 km/h. Three levels of occupant restraint, completely unrestrained, three-point seat belt, and three-point seat belt with an airbag, are investigated. The strains developed in the uterus because of loading from the seat belt and steering-wheel unit are presented, together with an analysis of stress distribution due to inertial loading of the fetus on the uterus. The unrestrained cases are shown to be the most dangerous to the fetus, owing to the large interaction with the vehicle steering wheel at the level of the placenta. The use of a three-point seat belt together with a driver airbag appears to offer the greatest protection to the fetus

A computational model of the human head and neck system for the analysis of whiplash motion

This paper presents the development and validation of a three-dimensional multi-body model of the human head and neck for the study of whiplash motion. The model has been validated against experimental data for small and large static loading conditions. The resulting main and coupled displacements of the individual motion segments have been shown to be accurate and the moment generating capacity of the neck muscle elements realistic. The model has been used for the dynamic simulation of impacts in frontal, lateral and rear-end directions. For rear-end impacts the characteristics of ‘whiplash’ motion have been accurately reproduced in terms of head and vertebral kinematics The model results with active musculature suggest that, for rear-end impact, the influence of active muscle response is unable to significantly alter the head and neck kinematics of an initially unaware occupant but will affect the forces developed in the cervical soft-tissues

Computational analysis of the bonding process and structure of the bond point during through air bonding

Though-air bonding is one of the methods of bonding fibres in nonwoven webs. A computational study of the formation of bond point between two bicomponent fibres during the through-air bonding is reported in this paper. The computational method involves solving the Navier-Stokes equations for two-phase flows of air and molten polymer in a three-dimensional configuration. The heating, melting and bonding of fibres are modelled by the Volume of Fluid (VOF) model together with a melting model. The simulated results show the formation of the bond between two fibres in contact and the change of shape of the bond with time at different bonding temperatures. The computation shows that the rate of bonding increases slightly at higher temperature

'Expecting': occupant model incorporating anthropometric details of pregnant women

This study reports the research for a design tool related to pregnant women’s safety during car travel. Anthropometric measurements are taken to generate an occupant model incorporating pregnancy related changes. These anthropometric changes mean that a pregnant occupant may be excluded by the designs, based upon non-pregnant female anthropometry. The paper explains the generation of a comprehensive parametric computer aided model of a pregnant occupant, ‘Expecting’. The model can represent different size pregnant occupants as well as the size differences occurring in standing and seated postures. This model can be used as a design tool for automotive designers to help ensure that vehicle designs can accommodate the anthropometric needs of pregnant occupants

Flattening of 3D data

The digital library project strives to digitise special collections of libraries; this consists in storing as binary data, photographs of the content of ancient or rare manuscripts. The object is typically not in a flat plane. One collects, along with the photograph of the unflattened object (and the inevitably distorted text), a positional reading of its surface using laserometer. It is then a mathematical problem of how to use the latter information to undo the distortion of the photograph before storing the digitised image. We discuss a variational formulation and implementation of thi

Predicting clinical outcomes in neuroblastoma with genomic data integration

Background: Neuroblastoma is a heterogeneous disease with diverse clinical outcomes. Current risk group models require improvement as patients within the same risk group can still show variable prognosis. Recently collected genome-wide datasets provide opportunities to infer neuroblastoma subtypes in a more unified way. Within this context, data integration is critical as different molecular characteristics can contain complementary signals. To this end, we utilized the genomic datasets available for the SEQC cohort patients to develop supervised and unsupervised models that can predict disease prognosis. Results: Our supervised model trained on the SEQC cohort can accurately predict overall survival and event-free survival profiles of patients in two independent cohorts. We also performed extensive experiments to assess the prediction accuracy of high risk patients and patients without MYCN amplification. Our results from this part suggest that clinical endpoints can be predicted accurately across multiple cohorts. To explore the data in an unsupervised manner, we used an integrative clustering strategy named multi-view kernel k-means (MVKKM) that can effectively integrate multiple high-dimensional datasets with varying weights. We observed that integrating different gene expression datasets results in a better patient stratification compared to using these datasets individually. Also, our identified subgroups provide a better Cox regression model fit compared to the existing risk group definitions. Conclusion: Altogether, our results indicate that integration of multiple genomic characterizations enables the discovery of subtypes that improve over existing definitions of risk groups. Effective prediction of survival times will have a direct impact on choosing the right therapies for patients.No sponso

Anti-microbial Use in Animals: How to Assess the Trade-offs

Antimicrobials are widely used in preventive and curative medicine in animals. Benefits from curative use are clear – it allows sick animals to be healthy with a gain in human welfare. The case for preventive use of antimicrobials is less clear cut with debates on the value of antimicrobials as growth promoters in the intensive livestock industries. The possible benefits from the use of antimicrobials need to be balanced against their cost and the increased risk of emergence of resistance due to their use in animals. The study examines the importance of animals in society and how the role and management of animals is changing including the use of antimicrobials. It proposes an economic framework to assess the trade-offs of anti-microbial use and examines the current level of data collection and analysis of these trade-offs. An exploratory review identifies a number of weaknesses. Rarely are we consistent in the frameworks applied to the economic assessment anti-microbial use in animals, which may well be due to gaps in data or the prejudices of the analysts. There is a need for more careful data collection that would allow information on (i) which species and production systems antimicrobials are used in, (ii) what active substance of antimicrobials and the application method and (iii) what dosage rates. The species need to include companion animals as well as the farmed animals as it is still not known how important direct versus indirect spread of resistance to humans is. In addition, research is needed on pricing antimicrobials used in animals to ensure that prices reflect production and marketing costs, the fixed costs of anti-microbial development and the externalities of resistance emergence. Overall, much work is needed to provide greater guidance to policy, and such work should be informed by rigorous data collection and analysis systems