952 research outputs found
Numerical modelling and in-vitro studies of ultrasound signal loss across fractures in cortical bone mimics
No full textThe propagation of 200 kHz ultrasonic waves along cortical bone mimics and across a simulated fracture has been investigated using a Finite Difference numerical model. The first arrival signal (FAS) transit time and peak amplitude have been calculated as a function of range at 200kHz in order to help understand the factors that determine the propagation across a fracture. The variation in the amplitude of the first peak of the reradiated wave is studied as a function of the gap width and shape. The results compare well with experimental measurements made in vitro using an axial transmission technique on cortical bone mimics and bovine cortical bone samples. The effects of various stages of the healing process have also been considered by introducing different fracture geometries into the plate model. Changing the geometry to an external callus with different mechanical properties causes the signal loss across the fracture to reduce significantly. The most significant changes are observed to occur from the initial inflammatory stage to the formation of a callus and in the remodelling stage after a significant reduction in the size of the callus has taken place
Making connections: problems, progress and priorities – a practitioner’s viewpoint
No full textIn this thesis, the reader is invited to ‘think with the story’ (Bochner, 1997) as the issues arising from a research project undertaken by a full-time classroom teacher are explored. The study began with the intention to help children make connections in their learning. Taking an action research approach, over a span of two and a half years, ways to help children link ideas were investigated, their responses observed and their views explored through techniques such as interviews, games and stimulated recall. As the study progressed, it developed a stronger focus on practitioner research, especially in relation to teacher research with children. Following a change of school, the research focused on working with a ‘pupil research group’ over a six-month period. The thesis addresses the learning of the teacher-researcher about the connections and challenges involved, including contextual issues, different methodological strategies, power relationships, different voices and viewpoints in research and the process of change. A narrative approach is used to tell much of the story, in the form of an informal dialogue between the author as a teacher and the author as a researcher. Thus, the common and conflicting demands and benefits of research and teaching in such a project are explored in dynamic fashion. Ultimately, a framework to support practitioner researchers, based on the problems and progress in the study, is presented with some priorities for the future
Ultrasound attenuation as a quantitative measure of fracture healing
No full textThe monitoring of fracture healing still relies upon the judgment of callus formation and on the manual assessment of the stiffness of the fracture. A diagnostic tool capable of quantitatively measuring healing progression of a fracture would allow the fine-tuning of the treatment regime. Ultrasound attenuation measurements were adopted as a possible method of assessing the healing process in human long bones. The method involves exciting ultrasonic waves at 200 kHz in the bone and measuring the reradiation along the bone and across the fracture zone. Seven cadaveric femora were tested in vitro in intact form and after creating a transverse fracture by sawing through the cortex. The effects of five different fracture types were investigated. A partial fracture, corresponding to a 50% cut through the cortex, a closed fracture, and fractures of widths varying between 1, 2, and 4 mm were investigated. The introduction of a fracture was found to produce a dramatic effect on the amplitude of the signal. Ultrasound attenuation was found to be sensitive to the presence of a fracture, even when the fracture was well reduced. It would therefore appear feasible to adopt attenuation across a fracture as a quantitative measurement of fracture healing. <br/
Ultrasonic wave propagation in cortical bone mimics
No full textUnderstanding the velocity and attenuation of ultrasonic waves in cortical bone is important for studies of osteoporosis and fractures. In particular, propagation in free- and water-loaded acrylic plates, with a thickness range of around 1–6 mm, has been widely used to mimic cortical bone behavior. A theoretical investigation of Lamb mode propagation at 200 kHz in free- and water-loaded acrylic plates revealed a marked difference in the form of their velocity and attenuation dispersion curves as a function of frequency thickness product. In experimental studies, this difference between free and loaded plates is not seen. Over short measurement distances, the results for both free and loaded plates are consistent with previous modeling and experimental studies: for thicker plates (above 3–4 mm), the velocity calculated using the first arrival signal is a lateral wave comparable with the longitudinal velocity. As the plate thickness decreases, the velocity approaches the S0 Lamb mode value. Wave2000 modeling of the experimental setup agrees with experimental data. The data are also used to test a hypothesis that for thin plates the velocity approaches the corresponding S0 Lamb mode velocity at large measurement distances or when different arrival time criteria are used
Ultrasound transmission loss across transverse and oblique bone fractures: an in vitro study
No full textAn axial transmission technique has been used to investigate the changes in the first arrival time and signal amplitude of 200 kHz ultrasonic waves travelling across different fracture geometries. Results taken from intact bovine femora were compared with those produced when a transverse and an oblique fracture were simulated. The arrival time and signal amplitude displayed a different variation with receiver position for the two geometries and a given fracture gap width. A comparison between this work and a previous study suggested that the marrow does not play a significant role in the mechanisms causing the change in arrival time and signal amplitude. Numerical modelling revealed that an oblique fracture caused a reduction in the extra time delay of the propagating wave compared with the transverse case, but a decrease in the corresponding signal amplitude, i.e., greater signal loss. The angle of the oblique fracture was investigated and results suggested that decreasing the fracture angle relative to the wave propagation direction caused a decrease in the extra time delay and an increase in signal loss. These findings are important for determining the sensitivity of systems for monitoring fracture healing using ultrasound arrival time and signal amplitude. (E-mail: [email protected]
<i>N,N′</i>-Dibutyloxamide
No full textN,N′-dibutyloxamide (1) was prepared by reacting diethyloxalate with n-butylamine in ethyl alcohol and characterized by microanalytical techniques, FT-IR, and NMR spectroscopy. Crystals suitable for single crystal X-ray diffraction (SC-XRD) were obtained from an acetonitrile solution of 1, and the structural characterization showed the presence of intermolecular hydrogen bonding interactions.</p
Contextualising and chronicling the gender equality provisions in FIFA’s 2016 governance reforms:Situating the FIFA Women’s World Cup 2023
No full textThis chapter situates the 2023 Fédération Internationale de Football Association (FIFA) Women's World Cup by contextualising and chronicling the gender equality statutory amendments passed at FIFA's Congress in February 2016. Co-author Moya Dodd, former member of Australia's women's national football team, was one of the first women on FIFA's Executive Committee and became “the driving force in the recent push for women within FIFA”. Dodd draws upon her first-hand experiences directing these reforms as chair of FIFA's Women's Football Taskforce, which drafted FIFA's Women's Football: 10 Key Development Principles. This chapter contextualises the FIFAGate crisis, introduces the Women's Football Taskforce proposals reflected in the 2016 FIFA Reform Report, and explains FIFA's passage of its gender equality statutory amendments. In so doing, the authors explain the process by which progress towards gender equality was, and can be, advanced within FIFA.</p
Environmental determinants of islet autoimmunity (ENDIA): a pregnancy to early life cohort study in children at-risk of type 1 diabetes
No full textMembers of ENDIA Study Group: Peter Baghurst, Simon Barry, Jodie Dodd, Maria Makrides for the University of Adelaide.BACKGROUND The incidence of type 1 diabetes has increased worldwide, particularly in younger children and those with lower genetic susceptibility. These observations suggest factors in the modern environment promote pancreatic islet autoimmunity and destruction of insulin-producing beta cells. The Environmental Determinants of Islet Autoimmunity (ENDIA) Study is investigating candidate environmental exposures and gene-environment interactions that may contribute to the development of islet autoimmunity and type 1 diabetes. METHODS/DESIGN ENDIA is the only prospective pregnancy/birth cohort study in the Southern Hemisphere investigating the determinants of type 1 diabetes in at-risk children. The study will recruit 1,400 unborn infants or infants less than six months of age with a first-degree relative (i.e. mother, father or sibling) with type 1 diabetes, across five Australian states. Pregnant mothers/infants will be followed prospectively from early pregnancy through childhood to investigate relationships between genotype, the development of islet autoimmunity (and subsequently type 1 diabetes), and prenatal and postnatal environmental factors. ENDIA will evaluate the microbiome, nutrition, bodyweight/composition, metabolome-lipidome, insulin resistance, innate and adaptive immune function and viral infections. A systems biology approach will be used to integrate these data. Investigation will be by 3-monthly assessments of the mother during pregnancy, then 3-monthly assessments of the child until 24 months of age and 6-monthly thereafter. The primary outcome measure is persistent islet autoimmunity, defined as the presence of autoantibodies to one or more islet autoantigens on consecutive tests. DISCUSSION Defining gene-environment interactions that initiate and/or promote destruction of the insulin-producing beta cells in early life will inform approaches to primary prevention of type 1 diabetes. The strength of ENDIA is the prospective, comprehensive and frequent systems-wide profiling from early pregnancy through to early childhood, to capture dynamic environmental exposures that may shape the development of islet autoimmunity. TRIAL REGISTRATION Australia New Zealand Clinical Trials Registry ACTRN12613000794707.Megan AS Penno, Jennifer J Couper, Maria E Craig, Peter G Colman, William D Rawlinson, Andrew M Cotterill, Timothy W Jones, Leonard C Harrison and ENDIA Study Grou
<i>N,N′</i>-Dipropyloxamide
No full textN,N′-Dipropyloxamide (1) was synthesised by the reaction between diethyloxalate and n-propylamine in ethanol. Compound 1 was fully characterised by both microanalytical (elemental analysis, melting point determination) and spectroscopic means (FT-IR and NMR spectroscopy). Crystals suitable for single crystal X-ray diffraction were isolated by the slow evaporation of a methyl alcohol solution of the compound. The resulting crystal structure shows the prominent role exerted by intermolecular hydrogen bonds in the crystal packing.</p
A BASELINE SUBTRACTION TOOL
No full textA. F. Ruckstuhl, M. P. Jacobson, R. W. Field, and J. A. Dodd, Journal of Quantitative Spectroscopy and Radiative Transfer, 68, 179-193 (2001).Author Institution: Massachusetts Institute of Technology; Department of Chemistry, Massachusetts Institute of Technology; Department of Chemistry, (Zurich University of Applied Sciences); Departement P, Zurcher Hochschule Winterthur, Columbia University; Department of Chemistry, Air Force Research LaboratoryAn Igor macro based on robust baseline estimation is introduced, which uses techniques of robust local regression to estimate baselines in spectra that consist of sharp features superimposed upon a continuous, slowly varying
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