Effect of culture conditions and calcium phosphate coating on ectopic bone formation

This study investigated the effect of a calcium phosphate (CaP) coating onto a polycaprolactone melt electrospun scaffold and in vitro culture conditions on ectopic bone formation in a subcutaneous rat model. The CaP coating resulted in an increased alkaline phosphatase activity (ALP) in ovine osteoblasts regardless of the culture conditions and this was also translated into higher levels of mineralisation. A subcutaneous implantation was performed and increasing ectopic bone formation was observed over time for the CaPcoated samples previously cultured in osteogenic media whereas the corresponding non-coated samples displayed a lag phase before bone formation occurred from 4 to 8 weeks post-implantation. Histology and immunohistochemistry revealed bone fill through the scaffolds 8 weeks post-implantation for coated and non-coated specimens and that ALP, osteocalcin and collagen 1 were present at the ossification front and in the bone tissues. Vascularisation in the vicinity of the bone tissues was also observed indicating that the newly formed bone was not deprived of oxygen and nutrients.We found that in vitro osteogenic induction was essential for achieving bone formation and CaP coating accelerated the osteogenic process. We conclude that high cell density and preservation of the collagenous and mineralised extracellular matrix secreted in vitro are factors of importance for ectopic bone formation.

Effect of real support conditions on the shear strength of hollow flange channel beams

This paper presents the details of experimental studies on the effect of real support conditions on the shear strength of LiteSteel beams (LSB). The LSB has a unique shape of a channel beam with two rectangular hollow flanges, made using a unique manufacturing process. In some applications in the building industry LSBs are used with only one web side plate (WSP) at their supports and are not used with full height web side plates (WSP) at their supports. Past research studies showed that theses real support connections did not provide simply supported conditions. Many studies have been carried out to evaluate the behaviour and design of LSBs with simply supported conditions subject to pure bending and predominant shear actions. To date, however, no investigation has been conducted into the effect of real support conditions on the shear strength of LSBs. Hence detailed experimental studies were undertaken to investigate the shear behaviour and strength of LSBs with real support conditions. A total of 28 experimental tests were conducted as part of the studies. Simply supported test specimens of LSBs with aspect ratios of 1.0 and 1.5 were loaded at mid-span until failure. It was found that the effect of using one WSP on the shear behaviour of LSB is significant and there is about 25% shear capacity reduction due to the lateral movement of the bottom flange at the supports. Shear capacity of LSB was also found to decrease when full height WSPs were not used. Suitable support connections were developed to improve the shear capacity of LSBs based on test results.

Experimental and numerical characteristics of portable water-filled road safety barrier system under different impact conditions

This research has developed an innovative road safety barrier system that will enhance roadside safety. In doing so, the research developed new knowledge in the field of road crash mitigation for high speed vehicle impact involving plastic road safety barriers. This road safety barrier system has the required feature to redirecting an errant vehicle with limited lateral displacement. Research was carried out using dynamic computer simulation technique support by experimental testing. Future road safety barrier designers may use the information in this research as a design guideline to improve the performance and redirectional capability of the road safety barrier system. This will lead to better safety conditions on the roadways and potentially save lives.

Accelerometer validity and placement for detection of changes in physical activity in dogs under controlled conditions on a treadmill

The objective of the research was to determine the optimal location and method of attachment for accelerometer-based motion sensors, and to validate their ability to differentiate rest and increases in speed in healthy dogs moving on a treadmill. Two accelerometers were placed on a harness between the scapulae of dogs with one in a pouch and one directly attached to the harness. Two additional accelerometers were placed (pouched and not pouched) ventrally on the dog's collar. Data were recorded in 1. s epochs with dogs moving in stages lasting 3. min each on a treadmill: (1) at rest, lateral recumbency, (2) treadmill at 0% slope, 3. km/h, (3) treadmill at 0% slope, 5. km/h, (4) treadmill at 0% slope, 7. km/h, (5) treadmill at 5% slope, 5. km/h, and; (6) treadmill at 5% slope, 7. km/h. Only the harness with the accelerometer in a pouch along the dorsal midline yielded statistically significant increases (P< 0.05) in vector magnitude as walking speed of the dogs increased (5-7. km/h) while on the treadmill. Statistically significant increases in vector magnitude were detected in the dogs as the walking speed increased from 5 to 7. km/h, however, changes in vector magnitude were not detected when activity intensity was increased as a result of walking up a 5% grade. Accelerometers are a valid and objective tool able to discriminate between and monitor different levels of activity in dogs in terms of speed of movement but not in energy expenditure that occurs with movement up hill.

Urban knowledge and innovation spaces : concepts, conditions, and contexts

Innovation is one of the key determinants of growth in the globalised knowledge economy, and ‘urban knowledge and innovation spaces’ form the spatial foci for sustained innovation. This paper aims to explore concepts, conditions and contexts that substantiate the development of these spaces of innovation. The paper seeks to identify the foundational elements of knowledge- based urban development to outline the concept of urban knowledge and innovation spaces, and justify its meaning, unique characteristics and growing influence in the contemporary cities. It rationalises the relevance of the three underlying conditions—namely policy, place, and people— to better understand their contribution in the development of such spaces. This paper sheds light over the varied contexts shaping each urban knowledge and innovation space uniquely. The paper reveals the interplay between design and policies that is required for the creation of spaces of innovation that are economically strong, socially connected, spatially stimulating, and environmentally sustainable.

Control of morphology and nucleation density of iron oxide nanostructures by electric conditions on iron surfaces exposed to reactive oxygen plasmas

The possibility to control the morphology and nucleation density of quasi-one-dimensional, single-crystalline α -Fe2 O3 nanostructures by varying the electric potential of iron surfaces exposed to reactive oxygen plasmas is demonstrated experimentally. A systematic increase in the oxygen ion flux through rf biasing of otherwise floating substrates and then an additional increase of the ion/neutral density resulted in remarkable structural transformations of straight nanoneedles into nanowires with controlled tapering/aspect ratio and also in larger nucleation densities. Multiscale numerical simulations relate the microscopic ion flux topographies to the nanostructure nucleation and morphological evolution. This approach is applicable to other metal-oxide nanostructures.

Internal oscillating current-sustained RF plasmas : Parameters, stability, and potential for surface engineering

A new source of low-frequency (0.46 MHz) inductively coupled plasmas sustained by the internal planar "unidirectional" RF current driven through a specially designed internal antenna configuration has been developed. The experimental results of the investigation of the optical and global argon plasma parameters by the optical and Langmuir probes are presented. It is shown that the spatial profiles of the electron density, the effective electron temperature and plasma potential feature a great deal of the radial and axial uniformity compared with conventional sources of inductively coupled plasmas with external at coil configurations. The measurements also reveal a weak azimuthal dependence of the global plasma parameters at low values of the input RF power, which was earlier predicted theoretically. The azimuthal dependence of the global plasma parameters vanishes at high input RF powers. Moreover, under certain conditions, the plasma becomes unstable due to spontaneous transitions between low-density (electrostatic, E) and high-density (electromagnetic, H) operating modes. Excellent uniformity of high-density plasmas makes the plasma reactor promising for various plasma processing applications and surface engineering.

Performance evaluation of three-level Z-source inverters under semiconductor-failure conditions

This paper evaluates and proposes various compensation methods for three-level Z-source inverters under semiconductor-failure conditions. Unlike the fault-tolerant techniques used in traditional three-level inverters, where either an extra phase-leg or collective switching states are used, the proposed methods for three-level Z-source inverters simply reconfigure their relevant gating signals so as to ride-through the failed semiconductor conditions smoothly without any significant decrease in their ac-output quality and amplitude. These features are partly attributed to the inherent boost characteristics of a Z-source inverter, in addition to its usual voltage-buck operation. By focusing on specific types of three-level Z-source inverters, it can also be shown that, for the dual Z-source inverters, a unique feature accompanying it is its extra ability to force common-mode voltage to zero even under semiconductor-failure conditions. For verifying these described performance features, PLECS simulation and experimental testing were performed with some results captured and shown in a later section for visual confirmation.

A meshfree particle based model for microscale shrinkage mechanisms of food materials in drying conditions

Cells are the fundamental building block of plant based food materials and many of the food processing born structural changes can fundamentally be derived as a function of the deformations of the cellular structure. In food dehydration the bulk level changes in porosity, density and shrinkage can be better explained using cellular level deformations initiated by the moisture removal from the cellular fluid. A novel approach is used in this research to model the cell fluid with Smoothed Particle Hydrodynamics (SPH) and cell walls with Discrete Element Methods (DEM), that are fundamentally known to be robust in treating complex fluid and solid mechanics. High Performance Computing (HPC) is used for the computations due to its computing advantages. Comparing with the deficiencies of the state of the art drying models, the current model is found to be robust in replicating drying mechanics of plant based food materials in microscale.

The influence of atmospheric conditions on the leakage current of ceramic insulators on the Colombian Caribbean coast

The contamination of electrical insulators is one of the major contributors to the risk of operation outages in electrical substations, especially in coastal zones with high salinity levels and atmospheric pollution. By using the measurement of leakage-currents, which is one of the main indicators of contamination in insulators, this work seeks to the determine the correlation with climatic variables, such as ambient temperature, relative humidity, solar irradiance, atmospheric pressure, and wind speed and direction. The results obtained provide an input to the behaviour of the leakage current under atmospheric conditions that are particular to the Caribbean coast of Colombia. Spearman’s rank correlation coefficients and principal component analysis are utilised to determine the significant relationships among the different variables under consideration. The necessary information for the study was obtained via historical databases of both atmospheric variables and the leakage current measured in over a period of one year in a 220-kV potential transformer insulator. We identified the influencing factors of temperature, humidity, radiation, wind speed and direction on the magnitude of the leakage current as the most relevant.

An analytical framework for quantifying aquifer response time scales associated with transient boundary conditions

A major challenge in studying coupled groundwater and surface-water interactions arises from the considerable difference in the response time scales of groundwater and surface-water systems affected by external forcings. Although coupled models representing the interaction of groundwater and surface-water systems have been studied for over a century, most have focused on groundwater quantity or quality issues rather than response time. In this study, we present an analytical framework, based on the concept of mean action time (MAT), to estimate the time scale required for groundwater systems to respond to changes in surface-water conditions. MAT can be used to estimate the transient response time scale by analyzing the governing mathematical model. This framework does not require any form of transient solution (either numerical or analytical) to the governing equation, yet it provides a closed form mathematical relationship for the response time as a function of the aquifer geometry, boundary conditions, and flow parameters. Our analysis indicates that aquifer systems have three fundamental time scales: (i) a time scale that depends on the intrinsic properties of the aquifer; (ii) a time scale that depends on the intrinsic properties of the boundary condition, and; (iii) a time scale that depends on the properties of the entire system. We discuss two practical scenarios where MAT estimates provide useful insights and we test the MAT predictions using new laboratory-scale experimental data sets.

A time series analysis of presentations to Queensland health facilities for alcohol-related conditions, following the increase in 'alcopops' tax

Objective: In response to concerns about the health consequences of high-risk drinking by young people, the Australian Government increased the tax on pre-mixed alcoholic beverages ('alcopops') favoured by this demographic. We measured changes in admissions for alcohol-related harm to health throughout Queensland, before and after the tax increase in April 2008. Methods: We used data from the Queensland Trauma Register, Hospitals Admitted Patients Data Collection, and the Emergency Department Information System to calculate alcohol-related admission rates per 100,000 people, for 15 - 29 year-olds. We analysed data over 3 years (April 2006 - April 2009), using interrupted time-series analyses. This covered 2 years before, and 1 year after, the tax increase. We investigated both mental and behavioural consequences (via F10 codes), and intentional/unintentional injuries (S and T codes). Results: We fitted an auto-regressive integrated moving average (ARIMA) model, to test for any changes following the increased tax. There was no decrease in alcohol-related admissions in 15 - 29 year-olds. We found similar results for males and females, as well as definitions of alcohol-related harms that were narrow (F10 codes only) and broad (F10, S and T codes). Conclusions: The increased tax on 'alcopops' was not associated with any reduction in hospital admissions for alcohol-related harms in Queensland 15 - 29 year-olds.

Age, physical inactivity, obesity, health conditions, and health-related quality of life among patients receiving conservative management for musculoskeletal disorders

Background Musculoskeletal conditions and insufficient physical activity have substantial personal and economic costs among contemporary aging societies. This study examined the age distribution, comorbid health conditions, body mass index (BMI), self-reported physical activity levels, and health-related quality of life of patients accessing ambulatory hospital clinics for musculoskeletal disorders. The study also investigated whether comorbidity, BMI, and self-reported physical activity were associated with patients’ health-related quality of life after adjusting for age as a potential confounder. Methods A cross-sectional survey was undertaken in three ambulatory hospital clinics for musculoskeletal disorders. Participants (n=224) reported their reason for referral, age, comorbid health conditions, BMI, physical activity levels (Active Australia Survey), and health-related quality of life (EQ-5D). Descriptive statistics and linear modeling were used to examine the associations between age, comorbidity, BMI, intensity and duration of physical activity, and health-related quality of life. Results The majority of patients (n=115, 51.3%) reported two or more comorbidities. In addition to other musculoskeletal conditions, common comorbidities included depression (n=41, 18.3%), hypertension (n=40, 17.9%), and diabetes (n=39, 17.4%). Approximately one-half of participants (n=110, 49.1%) self-reported insufficient physical activity to meet minimum recommended guidelines and 150 (67.0%) were overweight (n=56, 23.2%), obese (n=64, 28.6%), severely obese (n=16, 7.1%), or very severely obese (n=14, 6.3%), with a higher proportion of older patients affected. A generalized linear model indicated that, after adjusting for age, self-reported physical activity was positively associated (z=4.22, P<0.001), and comorbidities were negatively associated (z=-2.67, P<0.01) with patients’ health-related quality of life. Conclusion Older patients were more frequently affected by undesirable clinical attributes of comorbidity, obesity, and physical inactivity. However, findings from this investigation are compelling for the care of patients of all ages. Potential integration of physical activity behavior change or other effective lifestyle interventions into models of care for patients with musculoskeletal disorders is worthy of further investigation.