1) FINITE-ELEMENT MODELING AND PATIENT-SPECIFIC PREDICTION OF ANEURYSM GROWTH AND RUPTURE IN THE ASCENDING THORACIC AORTA 

Keywords: Finite-element method, nonlinear mechanics, mechanobiology, aortic aneurysm, extracellular matrix degeneration, nonlocal mechanics, fluid-structure interactions.

Academic context: This PhD thesis is part of the interdisciplinary Biolochanics – Localization in biomechanics and mechanobiology of aneurysms: Towards personalized medicine – project (2015-2020) awarded to Stéphane Avril (http://www.mines-stetienne.fr/stephane-avril) under the European Research Council Consolidator Grant scheme (http://erc.europa.eu/consolidator-grants). His group at Mines Saint-Etienne leads major international research projects in the domain of soft tissue biomechanics, focused especially on aortic aneurysm through a longstanding collaboration with the Saint-Etienne University Hospital. The Biolochanics project also relies on collaborations with Yale University (USA).

Scientific context: The growth of aortic aneurysms is associated with several mechano-chemo-biological interactions leading to modifications of the tissue structure including the fragmentation of elastin and changes in the amount and organization of collagen. We have modeled these mechanisms in a constitutive model based on the constrained mixture approach, where each constituent has an elastic constitutive response governed by an anisotropic strain energy function and an inelastic constitutive response governed first by a scalar [1–d]-type damage formulation and second by a permanent deformation gradient related to the growth. The model is implemented as a user material in the Abaqus software.

Project summary: In this thesis, we will first start by performing different sensitivity studies on the numerical model, permitting to calibrate different parameters, including the different degradation rates of collagen and elastin and the related time evolution of stress and strain distribution. Calibration will be performed against experimental data acquired by another person working on the project. After this stage we will apply the model to simulate the growth of ATAA in patients for whom we have reconstructed the aortic geometry for several years (on going longitudinal study at the university hospital of Saint-Etienne). In addition to the geometry, we have also access to hemodynamics through 4D MRI also acquired longitudinally for these patients, and even stiffness of the wall through an inverse method developed by another student working also on the project. All these data will be used to calibrate the finite-element model on a cohort of +20 patients in order to better understand how aneurysms grow and how the damage localizes in the tissue. The final goal will be to simulate numerically the scenario of growth and possible rupture for any patient’s aneurysm, just from the 4D MRI data, thus aiding the surgeon to take important decision such as surgical repair.

Candidate profile: Candidates with strong backgrounds in engineering mechanics, biophysics, biomechanics, and/or applied mathematics are expected. Background in finite elements and nonlinear mechanics will be highly appreciated. Motivation for ground-breaking experimental work and interest in mechanobiology are recommended.

Administrative aspects: Situated in the dynamic Rhône-Alpes region (Lyon – France) in the heart of the European Union, Mines-Saint-Etienne is one of the oldest and most prestigious Grandes Ecoles, and has, since 1816, lived up to its motto “innovante par tradition – inspiring innovation“. Working in a culturally and scientifically most stimulating atmosphere, the successful candidate will earn

internationally competitive salaries. Employment durations is 3 years. The employer is Armines, linked by state-approved agreements to Mines Saint-Etienne. The thesis will start in October 2017.

If you are interested, send a curriculum vitae, a cover letter describing previous research experience and interests, the names and contact information of two references. Please, submit via email with “ERC Biolochanics D3” on the subject line to Prof Stéphane AVRIL, PhD (avril@emse.fr). Deadline for applications: 30th April 2017.

2) MULTISCALE CHARACTERIZATION OF PROTEOLYTIC REMODELING  AND OF ITS BIOMECHANICAL EFFECTS IN THE AORTIC WALL 

Keywords: Mechanobiology, aortic aneurysm, extracellular matrix degeneration, biomechanical tests, full-field measurements, digital image correlation, OCT, collagenase

Academic context: This PhD thesis is part of the interdisciplinary Biolochanics – Localization in biomechanics and mechanobiology of aneurysms: Towards personalized medicine – project (2015-2020) awarded to Stéphane Avril (http://www.mines-stetienne.fr/stephane-avril) under the European Research Council Consolidator Grant scheme (http://erc.europa.eu/consolidator-grants). His group at Mines Saint-Etienne leads major international research projects in the domain of soft tissue biomechanics, focused especially on aortic aneurysm through a longstanding collaboration with the Saint-Etienne University Hospital. The Biolochanics project also relies on collaborations with Yale University (USA).

Scientific context: The growth of aortic aneurysms is associated with several morphological abnormalities, particularly in the media. Two abnormalities standout from a mechanical standpoint: the fragmentation of elastin and changes in the amount and organization of collagen. Changes in the organization of these two load-bearing components signal that more than likely significant changes in the mechanical properties are occurring.

Project summary: In this project, we will focus on the contribution of collagen, as the fragmentation of elastin has been implicated in the normal aging process. In aneurysms the normal production and degradation rates of collagen are disturbed leading to enlargement and local weakening of the aortic wall. To investigate this localized weakening of the tissue through degradation of its collagen fibers we will develop a novel biochemically-based method to locally degrade the collagen fibers and characterize its biomechanical effects.

Sample will be cut from aortic tissue and tested in an inflation device. Using a digital image correlation system at the macro scale (developed by a post-doc also working on the project) and an optical coherence tomography (OCT) system at the micro scale (developed by another post-doc), images will be recorded during the inflation. While the pressure is held constant, a fine tipped syringe will be used to apply purified collagenase in buffered saline to a small region of the sample. After the application of collagenase the sample and testing device will be placed in a saline bath for incubation. The selected incubation times are short to ensure that the collagen fibers are only partially degraded. To verify that the enzymatic digestion of collagen occurred we will examine histological images. After the treatment, we will inflate the tissue to failure. We will subject a total of 30 ATAA wall specimens to this protocol.

The stress and strain fields at each pressure stage will be calculated using an inverse method based on the data of the digital image correlation system at the macro scale and of the optical coherence tomography system. The focus will be on determining if any novel local features are identified in the collagenase treated region, particularly at physiologic pressure. We will use the calculated mechanical properties to confirm that the collagenase treatment had the intended effect of weakening the mechanical properties at the application site. The experimental method is fully capable of capturing these local changes in material properties. By comparing the range of rupture stress, we will determine how localized collagen degradation impacts the final rupture stress.

Candidate profile: Candidates with strong backgrounds in engineering mechanics, biophysics, biomechanics, and/or applied mathematics are expected. Background in experimental mechanics

and optical measurement techniques will be appreciated. Motivation for ground-breaking experimental work and interest in mechanobiology are recommended.

Administrative aspects: Situated in the dynamic Rhône-Alpes region (Lyon – France) in the heart of the European Union, Mines-Saint-Etienne is one of the oldest and most prestigious Grandes Ecoles, and has, since 1816, lived up to its motto “innovante par tradition – inspiring innovation“. Working in a culturally and scientifically most stimulating atmosphere, the successful candidate will earn internationally competitive salaries. Employment durations is 3 years. The employer is Armines, linked by state-approved agreements to Mines Saint-Etienne. The thesis will start in October 2017.

If you are interested, send a curriculum vitae, a cover letter describing previous research experience and interests, the names and contact information of two references. Please, submit via email with “ERC Biolochanics D2” on the subject line to Prof Stéphane AVRIL, PhD (avril@emse.fr). Deadline for applications: 30th April 2017.

Assessing the impact of hydrodynamic loads on shoulder joint injuries in swimming

Closing Date:   Monday 13 February 2017

Increasing activity and fitness levels across the general population is key to combatting the challenges associated with obesity and an ageing population. Swimming is considered to be beneficial as it offers a non weight-bearing, full-body form of cardiovascular exercise. These benefits might be offset, however, by an increased risk of shoulder injury, a common occurrence within the sport.

This project aims to investigate the mechanisms of shoulder injury through understanding how the hydrodynamic forces acting on a swimmer’s arm are supported by the musculoskeletal structure.

This project is fundamentally interdisciplinary requiring in-depth analysis of both complex fluid dynamics, biomechanics and intricate musculoskeletal systems within the body. The mechanisms of shoulder injury can be investigated through the use of a musculoskeletal model to simulate muscle response and joint loadings in different conditions. However this approach requires accurate stroke kinematics and hydrodynamic forces both of which are extremely challenging to measure in aquatic sports such as swimming.

The study will involve acquiring detailed kinematics of the swimming stroke and the use of advanced Computational Fluid Dynamics to simulate the pressure distribution over the arm. Different optical techniques will be utilised to assess the soft tissue deformations caused by fluid loading and muscle contraction during various tasks. Ultimately this information will be used to predict internal forces in the upper limb during swimming and elucidate on possible mechanisms of shoulder injury.

We are looking for applicants with a strong background in engineering, mathematics or physics, with an interest in sports and biomechanics. A fully funded 3 year studentship is available for UK/EU students, with the stipend at the standard RCUK rate (currently £14500 tax free).

Due to the interdisciplinary nature of this project supervision will be split between the Faculties of Engineering and the Environment and Health Sciences. This project is also supported by both British Swimming and the English Institute of Sport providing a wealth of expertise, support and access to world class biomechanists and coaches. This research will build on the previous experience and success of Southampton’s Performance Sport Engineering Lab and their support of British swimming in both the London and Rio Olympic games.

If you wish to discuss any details of the project informally, please contact Joseph Banks, Fluid Structure Interaction research group, Email: J.Banks@soton.ac.uk, Tel: +44 (0) 2380 59 6625.

Reference:  825117AT
Project Reference: CMEES-FSI-134

Read the advert and apply online here

Effect of low calories diet on the musculoskeletal health in UM-HET3 mice

Project Details: Age-delaying interventions are currently tested on animal models such as UM-HET3 mice. Among them, calorie restriction (CR) was found to increase the life-spam in mice models and has the potential of delay age-related pathologies. However, the effect of CR on the musculoskeletal health is still debated and becomes fundamental when studying its effect on musculoskeletal pathologies such as osteoarthritis (OA) and osteoporosis (OP).
The hypothesis of this study is that CR improves musculoskeletal health in old UM-HEY3 mice. In this project the student will characterise the properties of the knee joints and o whole tibiae of UM-HET3 mice in order to study the effect of CR on the properties of cartilage and bone and its relationship with gender and age. Tissues from female and male mice at three different ages (8, 12 and 22 months) have been already collected by our collaborators and will be analysed in Sheffield. The student will be taught how to perform state of the art assessments of OA and OP by combining micro-computed tomography (microCT) imaging, image processing and computational modelling. MicroCT allows us to acquire 3-dimensional high-resolution images of the whole bone and joint and to analyse in details their morphological and densitometric properties. Furthermore, microCT-based finite element (FE) models developed in Dall’Ara’s group are engineering methods that can provide a non-invasive assessment of bone mechanical properties from the acquired images. The assessment of degree of OA, bone morphometric parameters, distribution of bone mineral density within the tibia and bone strength will be provide a unique database for the characterisation of the effect of CR on bone and cartilage.

Entry Requirements

Candidates must have a first or upper second class honors degree or significant research experience. Strong imaging and/or computational background is required; experience with microCT image processing will be advantageous.

Funding

The Faculty of Medicine, Dentistry & Health Doctoral Academy Scholarships cover Home/EU fee and RCUK rate stipend for three years. Overseas students may apply but will need to fund the difference between the Home and Overseas fee from another source.

How to apply

Please apply through our online postgraduate application system including the Scholarship Application section where you need to tick the ‘University Scholarships’ box. The form will ask you to summarise your research proposal in less than 800 words. If you are unsure about what to put in this section, please contact your prospective supervisor. Please name your supervisor and select their department Oncology and Metabolism through the online form.

Deadline: 5pm 1st February 2017

Supervisors: Dr Enrico Dall’Ara, Department of Oncology and Metabolism and INSIGNEO institute for in silico medicine and Dr Ilaria Bellantuono, Department of Oncology and Metabolism.

Enquiries:
Interested candidates should in the first instance contact Dr Dall’Ara  e.dallara@sheffield.ac.uk

Doctoral student in Biomedical Engineering

Lund University, Faculty of Engineering, LTH, Biomedical Engineering

Lund University was founded in 1666 and is regularly ranked as one of the world’s top 100 higher education institutions. The University has 41 000 students and 7 500 staff based in Lund, Helsingborg and Malmö. We are united in our efforts to understand, explain and improve our world and the human condition.

LTH forms the Faculty of Engineering at Lund University, with approximately 9 000 students. The research carried out at LTH is of a high international standard and we are continuously developing our teaching methods and adapting our courses to current needs.

Project description

Can neutron scattering elucidate mechanisms behind bone damage?

Bone, with an inorganic strong and stiff mineral (hydroxyapatie) and a more flexible organic matrix (collagen type I), is a hierarchical tissue with unique material properties. During aging, many conditions occur which are treated with metal implants. E.g. joint replacements has generally evolved to be a success. However, patients still experience implant loosening due to insufficient bone in-growth, or local bone damage and failure close to the implant. Thus, improved bone ingrowth onto metal implants is still needed.

Without doubt, X-ray based imaging modalities are state-of-the-art for investigating bone both in daily clinical practice and in high end research. However, when metal implants are involved, the high density contrast between metal and bone often results in significant artifacts in the close proximity of the implant, i.e. in the most important region for evaluation bone-implant in-growth. Moreover, we have shown that bone fragility may be highly linked to changes in the collagen matrix, something that is not well captured with X-rays. The absorption profile of neutrons is however very different. Neutrons are more strongly attenuated by hydrogen and organic material than e.g. metals, but their potential in bone research has not yet been explored.

The objectives are to understand bone damage and fracture mechanisms on various hierarchical levels and with focus on bone ingrowth on implants, the goal of this project is to explore the potential of neutron tomographic imaging and small angle scattering in studies of bone.

The project includes designing and carry out experiments at large scale facilities, followed by data analysis. The imaging part involves using Digital Image Correlation to follow the deformation of the tissue during loading, and to link the different length scales of the tissue to each other. The project will develops the use of neutron based methods on bone. As such it will open up the field of neutrons to a large potential user group interested in musculoskeletal and medical materials.

SwedNESS: The project is a part of SweNESS, the newly initiated national graduate school for Neutron research. Please see link for more information http://swedness.se/

Work duties

The main duties of doctoral students are to devote themselves to their research studies which includes participating in research projects and third cycle courses. The work duties can also include teaching and other departmental duties (no more than 20%).

Detailed description of the work duties, such as:

• The research involves both experimental design and testing, tomographic and scattering imaging and analysis of data, including the use of digital image correlation.
• The doctoral student is expected to assist in supervision of MSc degree projects
• The project is a collaboration with Solid mechanics and Physical Chemistry at LU, and the doctoral student is expected to actively manage this collaboration.
• The doctoral student is expected to take part in the activities arranged by SweNESS graduate school.

Admission requirements

A person meets the general admission requirements for third-cycle courses and study programmes if he or she:

• has been awarded a second-cycle qualification, or

• has satisfied the requirements for courses comprising at least 240 credits of which at least 60 credits

were awarded in the second cycle, or

• has acquired substantially equivalent knowledge in some other way in Sweden or abroad.
• A person meets the specific admission requirements for third cycle studies in Biomedical Engineeringif he or she has at least 45 second-cycle credits of relevance to the subject.

Additional requirements:

• Very good oral and written proficiency in English.
• The candidate should have a background in (bio)engineering/ physics/chemistry or imaging.
• Experience with Neutron or Synchrotron based data collection or analysis is considered important
• Experience with tomographic imaging or small angle scattering is considered important.
• Experience with full-field strain measurement techniques is considered positive.

Assessment criteria

Selection for third-cycle studies is based on the student’s potential to profit from such studies. The assessment of potential is made primarily on the basis of academic results from the first and second cycle. Special attention is paid to the following:

• Knowledge and skills relevant to the thesis project and the subject of study.
• An assessment of ability to work independently and to formulate and tackle research problems.
• Written and oral communication skills.
• Other experience relevant to the third-cycle studies, e.g. professional experience. Other assessment criteria:
• The candidate should be able to independently drive his/her own research project, as well as writing scientific publications.
• The candidate should be able to supervise younger researchers.
• Experience with multidisciplinary projects is important.
• International experience is considered positive.

Consideration will also be given to good collaborative skills, drive and independence, and how the applicant, through his or her experience and skills, is deemed to have the abilities necessary for successfully completing the third cycle programme.

Conditions

Only those admitted to third cycle studies may be appointed to a doctoral studentship. Third cycle studies at LTH consist of full-time studies for 4 years. A doctoral studentship is a fixed-term employment of        a maximum of 5 years (including 20% departmental duties). Doctoral studentships are regulated in the Higher Education Ordinance (1998:80).

Instructions on how to apply

Applications shall be written in English and include a cover letter stating the reasons why you are interested in the position and in what way the research project corresponds to your interests and educational background. The application must also contain a CV, degree certificate or equivalent, and other documents you wish to be considered (grade transcripts, contact information for your references, letters of recommendation, etc.).

Lund University welcomes applicants with diverse backgrounds and experiences. We regard gender equality and diversity as a strength and an asset.

Type of employment                              Temporary position longer than 6 months

First day of employment                       As per argreement. Initially 1 year and thereafter extended

Salary                                                     Monthly salary

Number of positions                             1

Working hours                                      100 %

City                                                         Lund

County                                                   Skåne län

Country                                                  Sweden

Reference number                                 PA2016/4605

Contact                                                   Hanna Isaksson +46462221749 Johan Nilsson +46462227532

Published                                               2016-12-19

Last application date                            2017-01-31

Link to ad                                                http://lu.mynetworkglobal.com/what:job/jobID:127473/