Thermal-elastic stresses and the criticality of the continental crust

Heating or cooling can lead to high stresses in rocks due to the different thermal-elastic properties of minerals. In the upper 4 km of the crust, such internal stresses might cause fracturing. Yet it is unclear if thermal elasticity contributes significantly to critical stresses and failure deeper in Earth's continental crust, where ductile creep causes stress relaxation. We combined a heating experiment conducted in a Synchrotron microtomograph (Advanced Photon Source, USA) with numerical simulations to calculate the grain-scale stress field in granite generated by slow burial. We find that deviatoric stresses >100 MPa can be stored during burial, with relaxation times from 100's to 1000's ka, even in the ductile crust. Hence, grain-scale thermal-elastic stresses may serve as nuclei for instabilities, thus rendering the continental crust close to criticality.

Mechanical properties of mussel byssus threads

The byssus threads of the common mussel, Mytilus edulis L., have been tested mechanically and the results from the tests related to the ecology of the animal. The threads are mechanically similar to other crystalline polymers such as polyethylene having a modulus of about 108N m−2 and a long relaxation time. Resilience of 60% is similar to tendon; ultimate strain is about five times that of tendon at 0.44. The thread is laid down with a prestrain of 10% and so guys the mussel in position. Calculation shows that a mussel with 50 byssus threads would be able to resist all but severe winter storms.

Biomechanics of synthetic elastin : insights from Magnetic Resonance microimaging

We used Magnetic Resonance microimaging (μMRI) to study the compressive behaviour of synthetic elastin. Compression-induced changes in the elastin sample were quantified using longitudinal and transverse spin relaxation rates (R1 and R2, respectively). Spatially-resolved maps of each spin relaxation rate were obtained, allowing the heterogeneous texture of the sample to be observed with and without compression. Compression resulted in an increase of both the mean R1 and the mean R2, but most of this increase was due to sub-locations that exhibited relatively low R1 and R2 in the uncompressed state. This behaviour can be described by differential compression, where local domains in the hydrogel with a relatively low biopolymer content compress more than those with a relatively high biopolymer content.

Ab initio studies of hydrogen desorption from low index magnesium hydride surface

The low index Magnesium hydride surfaces, MgH2(0 0 1) and MgH2(1 1 0), have been studied by ab intio Density Functional Theory (DFT) calculations. It was found that the MgH2(1 1 0) surface is more stable than MgH2(0 0 1) surface, which is in good agreement with the experimental observation. The H2 desorption barriers vary depending on the crystalline surfaces that are exposed and also the specific H atom sites involved – they are found to be generally high, due to the thermodynamic stability of the MgH2 system, and are larger for the MgH2(0 0 1) surface. The pathway for recombinative desorption of one in-plane and one bridging H atom from the MgH2(1 1 0) surface was found to be the lowest energy barrier amongst those computed (172 KJ/mol) and is in good agreement with the experimental estimates.

Improving sleep quality for patients after cardiac surgery

Research has consistently described that patients after cardiac surgery experience disturbed sleep yet there has been limited investigation into methods to improve this experience. Complementary therapies may be a method of addressing this issue. Aim: To determine if using progressive muscle relaxation improves self-rated sleep quality for patients following cardiac surgery. Methods and Results: Thirty-five participants' quantitative data on sleep quality were obtained via questionnaire during their first post-operative week after cardiac surgery. Qualitative data were obtained through written responses to open-ended questions. No significant differences in sleep quality scores were found between pre and post-intervention of progressive muscle relaxation using the Wilcoxon Signed Ranks Test. However, the qualitative analysis discovered the intervention aided some participants in initiating their sleep by diversion of thought, inducing relaxation or alleviating pain and anxiety. Conclusions: Qualitative findings suggest that progressive muscle relaxation may help patients who have undergone cardiac surgery initiate their sleep.

Numerical simulation of anomalous diffusion with application to medical imaging

The first objective of this project is to develop new efficient numerical methods and supporting error and convergence analysis for solving fractional partial differential equations to study anomalous diffusion in biological tissue such as the human brain. The second objective is to develop a new efficient fractional differential-based approach for texture enhancement in image processing. The results of the thesis highlight that the fractional order analysis captured important features of nuclear magnetic resonance (NMR) relaxation and can be used to improve the quality of medical imaging.

Review essay -- Weber L and Pickering S (2011) Globalization and borders : death at the global frontier

The pertinence of this book cannot be overemphasised. The world’s refugee crisis has reached a two‐decade high with the United Nations recently announcing that ‘displacement is the new 21st century challenge’ (UNHCR 2013). The transnational movement of dislocated peoples fleeing conflict, persecution and poverty is a global responsibility requiring nation states to collaborate for humanitarian resolutions embedded in human rights. However, in times of human rights expansionism, and the relaxation of borders for maximising free‐trade and fiscal prosperity, the movement of people experiencing immense abuse and deprivation has witnessed an increase in draconian regulation within discourses of intolerance and deterrence. Weber and Pickering cogently and emphatically emphasise the human cost of inhumane and populist government immigration and border‐entry polices underpinned by ideologies of retribution, suspicion, and demonisation. It is a moving and engaging narrative: a book that exposes state prejudice and abuse, whilst advocating for the victims who undertake perilous journeys in search of safety from lives of violence and persecution. Moreover, it is a book that pushes ideological boundaries and seeks new criminological horizons, for which the authors must be sincerely congratulated. It is a text of innovation, inspired thinking and long lasting criminological value.

Porohyperelastic analysis of single chondrocyte using AFM and inverse FEA

The aim of this paper is to determine the creep and relaxation responses of single chondrocytes in vitro. Firstly, Atomic Force Microscopy (AFM) was used to obtain the force-indentation curves of single chondrocytes at the strain-rate of 7.05 s-1. This result was then employed in inverse finite element analysis (FEA) using porohyperelastic (PHE) idealization of the cells to determine their mechanical properties. The PHE model results agreed well with AFM experimental data. This PHE model was then utilized to study chondrocyte’s creep and relaxation behaviors. The results revealed that the effect of fluid was predominant for cell’s mechanical behaviors and that the PHE is a good model for biomechanics studies of chondrocytes.

Foot massage versus quiet presence on agitation and mood in people with dementia : a randomised controlled trial

Background There is increasing interest in using complementary and alternative treatments to manage behavioural and psychological symptoms of dementia such as agitation, aggression and depressed mood. Objective To compare the effect of foot massage (intervention) and quiet presence (control) on agitation and mood in people with dementia. Design A randomised controlled trial using a within-subjects, crossover design. Settings Five long-term care facilities in Brisbane, Australia. The primary outcome was the Cohen-Mansfield Agitation Inventory (CMAI) and the secondary outcome was the Observed Emotion Rating Scale (OERS). The screening and data collection research assistants, families, and care staff were blinded to participant allocation. Participants Participants of the study were 55 long-term care residents aged 74–103 years (mean age 86.5), with moderate to severe dementia and a history of agitated behaviour according to the Pittsburgh Agitation Scale. A computer-program randomised participants to 10-min foot massage (intervention) or quiet presence (control), every weekday for 3 weeks. Results A carry-over effect was identified in the data, and so the data was treated as a parallel groups RCT. The mean total CMAI increased in both groups (reflecting an increase in agitation) with this increase greater in the quiet presence group than the foot massage group (p=0.03). There was a trend towards a difference on OERS General Alertness, with a positive change in alertness for participants in the foot massage group (indicating reduced alertness) and a negative change for participants in the quiet presence group (indicating increased alertness) (F(1,51)=3.88, p=0.05, partial ή2=0.07). Conclusions The findings highlight the need for further research on the specific conditions under which massage might promote relaxation and improve mood for people with dementia. The unfamiliar research assistants and variations in usual activity may have contributed to the increase in agitation and this needs further research.

Foot massage and physiological stress in people with dementia : a randomized controlled trial

Background There is increasing interest in using complementary and alternative treatments to manage behavioural and psychological symptoms of dementia such as agitation, aggression and depressed mood. Objective To compare the effect of foot massage (intervention) and quiet presence (control) on agitation and mood in people with dementia. Design A randomised controlled trial using a within-subjects, crossover design. Settings Five long-term care facilities in Brisbane, Australia. The primary outcome was the Cohen-Mansfield Agitation Inventory (CMAI) and the secondary outcome was the Observed Emotion Rating Scale (OERS). The screening and data collection research assistants, families, and care staff were blinded to participant allocation. Participants Participants of the study were 55 long-term care residents aged 74–103 years (mean age 86.5), with moderate to severe dementia and a history of agitated behaviour according to the Pittsburgh Agitation Scale. A computer-program randomised participants to 10-min foot massage (intervention) or quiet presence (control), every weekday for 3 weeks. Results A carry-over effect was identified in the data, and so the data was treated as a parallel groups RCT. The mean total CMAI increased in both groups (reflecting an increase in agitation) with this increase greater in the quiet presence group than the foot massage group (p=0.03). There was a trend towards a difference on OERS General Alertness, with a positive change in alertness for participants in the foot massage group (indicating reduced alertness) and a negative change for participants in the quiet presence group (indicating increased alertness) (F(1,51)=3.88, p=0.05, partial ή2=0.07). Conclusions The findings highlight the need for further research on the specific conditions under which massage might promote relaxation and improve mood for people with dementia. The unfamiliar research assistants and variations in usual activity may have contributed to the increase in agitation and this needs further research.

Exploring the effect of aquatic exercise on behaviour and psychological wellbeing in people with moderate to severe dementia : a pilot study of the Watermemories Swimming Club

Aim To explore the effects of a dementia-specific, aquatic exercise intervention on behavioural and psychological symptoms in people with dementia (BPSD). Method Residents from two aged care facilities in Queensland, Australia, received a 12-week intervention consisting of aquatic exercises for strength, agility, flexibility, balance and relaxation. The Psychological Well-Being in Cognitively Impaired Persons Scale (PW-BCIP) and the Revised Memory and Behaviour Problems Checklist (RMBPC) were completed by registered nurses at baseline, week 6, week 9 and post intervention. Results Ten women and one man (median age = 88.4 years, interquartile range = 12.3) participated. Statistically significant declines in the RMBPC and PW-BCIP were observed over the study period. Conclusion Preliminary evidence suggests that a dementia-specific, aquatic exercise intervention reduces BPSD and improves psychological well-being in people with moderate to severe dementia. With further testing, this innovative intervention may prove effective in addressing some of the most challenging aspects of dementia care.

The Watermemories Swimming Club

This pilot project aimed to try something different - rekindle positive memories of swimming in people with dementia who enjoyed swimming throughout their lives, and involve them in active swimming again using a swimming club intervention. Club members were recruited from two residential aged care facilities in Queensland, Australia (n=25 recruited, n=18 commenced, n=11 (median age=88.4, IQR=12.3; 1 male) completed the intervention). The 12 week program consisted of two, 45 minute sessions per week held at a municipal pool, using a trained instructor and assistants. Measures, taken at baseline, Week 6, Week 9 and post intervention included psychosocial and physical assessments such as the Revised Memory and Behavior Problems Checklist, Psychological Well-Being in Cognitively Impaired Persons, Seniors Physical Performance Battery and bioelectric impedance analysis. Stakeholder focus groups determined the barriers and facilitators for the club. Three outcomes have been achieved: 1) the development of a dementia specific, evidence-based, aquatic exercise program. This valuable resource will ensure that the benefits will be maximized with tailored exercises for strength, agility, flexibility, balance, relaxation and stress reduction, 2) improved quality of life for members, with statistically significant improvements in psychological wellbeing (χ2 =8.66, p<0.05), BPSD expression (χ2=16.91, p=0.001) and staff distress (χ2=16.86, p=0.001) and 3) an informative website with instructional video clips and a manual to assist others in implementing and maintaining a Watermemories Swimming Club. This pilot project has provided strong evidence that aquatic exercise can produce positive physical, psychosocial and behavioral outcomes for people with dementia.

Numerical study of lid-driven square cavity with heat generation using LBM

In this study, the mixed convection heat transfer and fluid flow behaviors in a lid-driven square cavity filled with high Prandtl number fluid (Pr = 5400, ν = 1.2×10-4 m2/s) at low Reynolds number is studied using thermal Lattice Boltzmann method (TLBM) where ν is the viscosity of the fluid. The LBM has built up on the D2Q9 model and the single relaxation time method called the Lattice-BGK (Bhatnagar-Gross-Krook) model. The effects of the variations of non dimensional mixed convection parameter called Richardson number(Ri) with and without heat generating source on the thermal and flow behavior of the fluid inside the cavity are investigated. The results are presented as velocity and temperature profiles as well as stream function and temperature contours for Ri ranging from 0.1 to 5.0 with other controlling parameters that present in this study. It is found that LBM has good potential to simulate mixed convection heat transfer and fluid flow problem. Finally the simulation results have been compared with the previous numerical and experimental results and it is found to be in good agreement.

Investigation on Temperature-Dependent Electrical Conductivity of Carbon Nanotube/Epoxy Composites for Sustainable Energy Applications

Composites with carbon nanotubes are becoming increasingly used in energy storage and electronic devices, due to incorporated excellent properties from carbon nanotubes and polymers. Although their properties make them more attractive than conventional smart materials, their electrical properties are found to be temperature-dependent which is important to consider for the design of devices. To study the effects of temperature in electrically conductive multi-wall carbon nanotube/epoxy composites, thin films were prepared and the effect of temperature on the resistivity, thermal properties and Raman spectral characteristics of the composite films was evaluated. Resistivity-temperature profiles showed three distinct regions in as-cured samples and only two regions in samples whose thermal histories had been erased. In the vicinity of the glass transition temperature, the as-cured composites exhibited pronounced resistivity and enthalpic relaxation peaks, which both disappeared after erasing the composites’ thermal histories by temperature cycling. Combined DSC, Raman spectroscopy, and resistivity-temperature analyses indicated that this phenomenon can be attributed to the physical aging of the epoxy matrix and that, in the region of the observed thermal history-dependent resistivity peaks, structural rearrangement of the conductive carbon nanotube network occurs through a volume expansion/relaxation process. These results have led to an overall greater understanding of the temperature-dependent behaviour of conductive carbon nanotube/epoxy composites, including the positive temperature coefficient effect.

Analysis of strain-rate dependent mechanical behavior of single chondrocyte : a finite element study

Various studies have been conducted to investigate the effects of impact loading on cartilage damage and chondrocyte death. These have shown that the rate and magnitude of the applied strain significantly influence chondrocyte death, and that cell death occurred mostly in the superficial zone of cartilage suggesting the need to further understand the fundamental mechanisms underlying the chondrocytes death induced at certain levels of strain-rate. To date there is no comprehensive study providing insight on this phenomenon. The aim of this study is to examine the strain-rate dependent behavior of a single chondrocyte using a computational approach based on Finite Element Method (FEM). An FEM model was developed using various mechanical models, which were Standard Neo-Hookean Solid (SnHS), porohyperelastic (PHE) and poroviscohyperelastic (PVHE) to simulate Atomic Force Microscopy (AFM) experiments of chondrocyte. The PVHE showed, it can capture both relaxation and loading rate dependent behaviors of chondrocytes, accurately compared to other models.