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Red blood cells (RBCs) are the most abundant cells in human blood. Remarkably RBCs deform and bridge together to form aggregates under very low shear rates. The theory and mechanics behind aggregation are, however, not yet completely understood. The main objective of this work is to quantify and characterize RBC aggregates in order to enhance the current understanding of the non-Newtonian behaviour of blood in microcirculation. Suspensions of human blood were flowed and observed in vitro in poly-di-methyl-siloxane (PDMS) microchannels to characterize RBC aggregates. These microchannels were fabricated using standard photolithography methods. Experiments were performed using a micro particle image velocimetry (μPIV) system for shear rate measurements, coupled with a high-speed camera for flow visualization. RBC aggregate sizes were quantified in controlled and measurable shear rate environments for 5, 10 and 15% hematocrit. Aggregate sizes were determined using image processing techniques, while apparent viscosity was measured using optical viscometry. For the samples suspended at 5% H, aggregate size was not strongly correlated with shear rate. For the 10% H suspensions, in contrast, lowering the shear rate below 10 s-1 resulted in a significant increase of RBC aggregate sizes. The viscosity was found to increase with decreasing shear rate and increasing hematocrit, exemplifying the established non-Newtonian shear-thinning behaviour of blood. Increase in aggregation size did not translate into a linear increase of the blood viscosity. Temperature was shown to affect blood viscosity as expected, however, no correlation for aggregate size with temperature was observed. Non-Newtonian parameters associated with power law and Carreau models were determined by fitting the experimental data and can be used towards the simple modeling of blood's non-Newtonian behaviour in microcirculation. This work establishes a relationship between RBC aggregate sizes and corresponding shear rates and one between RBC aggregate sizes and apparent blood viscosity at body and room temperatures, in a microfluidic environment for low hematocrit. Effects of hematocrit, shear rate, viscosity and temperature on RBC aggregate sizes have been quantified.

A well-qualified, well-paid, stable workforce with high psychological and emotional wellbeing is critical to the provision of quality early childhood education and care, yet workforce shortages and high turnover persist in Australia and internationally. This paper uses ecological theory to conceptualise and make sense of findings from research that has investigated the recruitment, retention and wellbeing of early childhood teachers in Australia. The theoretical framing of early childhood teacher workforce issues proffered in the paper highlights the utility of considering these issues from a holistic ecological perspective. Analysis of Australian early childhood workforce studies draws attention to the need for large-scale, longitudinal research that holistically investigates influences on the attracting, retaining and sustaining of early childhood teachers, and the impact of these influences on teacher quality. [Author abstract]

Microcirculatory blood flow exhibits complex non-Newtonian behavior, including shear-thinning properties and the formation of a cell-free layer (CFL)-a plasma-rich region near vessel walls. While traditional rheological models such as Newtonian, Power Law, and Carreau describe certain flow characteristics, and empirical models like the double-parameter power fit have been used to capture velocity profiles, these approaches fall short in fully characterizing the dynamic interplay between red blood cells (RBCs) and plasma. This study introduces the Core-Plasma Model, a two-phase framework that integrates Newtonian and non-Newtonian elements to represent the RBC-rich core and surrounding CFL. In vitro experiments in 25 [Formula: see text]m and 50 [Formula: see text]m round channels across varying flow rates, hematocrit levels (5-20%), and suspending media (PBS and native plasma) demonstrate the model's superior ability to capture velocity and shear rate profiles. The Core-Plasma Model offers a robust platform for advancing microscale hemodynamic predictions and deepening the understanding of microvascular flow dynamics.

The placenta plays a critical role in nutrient and oxygen exchange during pregnancy, yet the effects of medicinal drugs on this selective barrier remain poorly understood. To overcome this, this study presents a cost-effective bioimpedance spectroscopy (BIS) system to assess tight junction integrity and monolayer formation in BeWo b30 cells, a widely used model of the multinucleated maternal–fetal exchange surface of the placental barrier. Cells were cultured on collagen-coated porous membranes and treated with forskolin to induce controlled syncytialization. Electrical impedance was measured using an entry level impedance analyzer, while immunofluorescence staining was used to confirm monolayer formation and syncytialization. The measurements and staining confirmed the formation of a confluent monolayer on day 4. In fact, the electrical resistance tripled for treated samples indicating a more electrically restrictive barrier. This resistance remained constant for treated samples reflecting the intact barrier’s integrity over the next 3 days. The measurements show that, on day 4, the electrical capacitance of the cells decreased for the treated samples as opposed to the untreated samples. This reflects that the surface area of the BeWo b30 cells decreased when the samples were treated with forskolin. Finally, a COMSOL model was developed to explore the effects of electrode positioning, depth, and distance on TEER measurements, explaining discrepancies in the literature. In fact, there was a substantial 97% and 39.4% difference in the obtained TEER values. This study demonstrates the AD2 device’s feasibility for monitoring placental barrier integrity and emphasizes the need for standardized setups for comparable results. The system can hence be used to analyze drug effects and nutrient transfer across the placental barrier.

Microfluidic devices are frequently manufactured with polydimethylsiloxane (PDMS) due to its affordability, transparency, and simplicity. However, high-pressure flow through PDMS microfluidic channels lead to an increase in channel size due to the compliance of the material. As a result, longer response times are required to reach steady flow rates, which increases the overall time required to complete experiments when using a syringe pump. Due to its excellent optical properties and increased rigidity, Norland Optical Adhesive (NOA) has been proposed as a promising material candidate for microfluidic fabrication. This study compares the compliance and deformation properties of three different characteristic sized (width of parallel channels: 100, 40 and 20 µm) microfluidic devices made of PDMS and NOA. The comparison of the microfluidics devices is made based on the Young’s modulus, roughness, contact angle, channel width deformation, flow resistance and compliance. The experimental resistance is estimated through the measurement of the flow at a given pressure and a precision flow meter. The characteristic time of the system is extracted by fitting the two-element resistance-compliance (RC) hydraulic circuit model. The compliance of the microfluidics chips is estimated through the measurement of the characteristic time required for channels to achieve an output flow rate equivalent to that of the input flow rate using a syringe pump and a precision flow meter. The Young modulus was found to be 2 MPa for the PDMS and 1743 MPa for the NOA 63. The surface roughness was found to be higher for the NOA 63 than for the PDMS. The hydrophilicities of materials were found comparable with and without plasma treatment. The results show that NOA devices have lower compliance and deformation than PDMS devices.

In a notable departure from long-standing childcare policy in Australia, in January 2016 fee relief was extended to nannies providing in-home care in a 2-year pilot program. This policy is significant as fee relief is not tied to the meeting of regulatory requirements designed to ensure quality early learning and care for young children. Drawing on Carol Bacchi's approach to policy analysis, this paper extends previous problematising of evidence-based policy by highlighting the value of first considering how a policy 'problem' has been constructed. We propose that the nanny pilot is an ideologically driven policy that has emanated from a construction of childcare that is adult (parent)-centred and marginalises the needs and interests of young children. Accordingly, certain evidence is privileged while other evidence is ignored, with the ensuing policy focused on economic imperatives rather than quality early learning and care experiences for young children. We draw on an analysis of parent, peak body and researcher submissions to the Productivity Commission's 2013-2014 childcare inquiry, nanny-focused research, and data from three national surveys to explore the limitations of such a policy approach. The utility of problem reconstruction as a means of disrupting policy-informed evidence and the legitimisation of purported evidence-based policy is considered.

While an increasing body of Australian and international research has explored the relationship between media and education, few studies have examined this relationship in the context of early childhood education. This paper contributes to this research gap by reporting on a corpus-assisted discourse analysis of how childcare is represented in 801 newspaper texts from six Australian newspapers. As a foundational paper of a broader study investigating public and political influences on parents' childcare choices, the paper details the use and utility of corpus linguistic tools for exploring the discourse construction of childcare in a large corpus of media texts. It also highlights the value of analysing media corpora via media ownership, focusing on the two dominant Australian media organisations, Fairfax and News Corp. Analyses reveal similarities but also key differences in the representation of childcare in Fairfax and News Corp newspapers. In Australia, print media still sets the daily media agenda and reflects the dominant discourse constructions surrounding major public issues. Accordingly, the beliefs, practices and decision-making of current and potential parent users of formal childcare may be differentially influenced depending not just on their (direct or indirect) access to print media, but by the format (tabloid or broadsheet) and thus ownership (Fairfax or News Corp). [Author abstract]

Teacher registration is increasingly utilised as a governance mechanism to audit teachers’ work and drive professional practice. There is limited and mixed empirical evidence, however, as to whether registration drives teaching quality. Our study extends this limited empirical base by critically examining the policy trajectory in Australia to bring early childhood teachers into a uniform system of registration with primary and secondary teachers. Adopting a relatively novel methodology, the study intertwined a critical social policy framing with a national quantitative survey. Results showed that respondents perceived their professional self, followed by their workplace (colleagues and employer) as key influencers of quality practice, and neither agreed nor disagreed that teacher registration was beneficial. Findings problematise the need for, and benefits of, teacher registration. That early childhood teachers’ practice and development was most driven by intrinsic motivation and, to a lesser extent, being employed in high-quality, not-for-profit, and preschool settings where other early childhood teachers are employed, suggests that more effective and progressive policy approaches to support quality early childhood education require an addressing of the contexts and conditions in which early childhood teachers work.

It is desired to understand the effect of alginic acid sodium salt from brown algae (alginate) as a viscosity modifier on the behavior of blood in vitro using a micro-particle image velocimetry (µPIV) system. The effect of alginate on the shape of the velocity profile, the flow rate and the maximum velocity achieved in rectangular microchannels channels are measured. The channels were constructed of polydimethylsiloxane (PDMS), a biocompatible silicone. Porcine blood cells suspended in saline was used as the working fluid at twenty percent hematocrit (H = 20). While alginate was only found to have minimal effect on the maximum velocity and the flow rate achieved, it was found to significantly affect the shear rate at the wall by between eight to a hundred percent.

In a notable departure from long-standing childcare policy in Australia, in January 2016 fee relief was extended to nannies providing in-home care in a 2-year pilot program. This policy is significant as fee relief is not tied to the meeting of regulatory requirements designed to ensure quality early learning and care for young children. Drawing on Carol Bacchi's approach to policy analysis, this paper extends previous problematising of evidence-based policy by highlighting the value of first considering how a policy 'problem' has been constructed. We propose that the nanny pilot is an ideologically driven policy that has emanated from a construction of childcare that is adult (parent)-centred and marginalises the needs and interests of young children. Accordingly, certain evidence is privileged while other evidence is ignored, with the ensuing policy focused on economic imperatives rather than quality early learning and care experiences for young children. We draw on an analysis of parent, peak body and researcher submissions to the Productivity Commission's 2013-2014 childcare inquiry, nanny-focused research, and data from three national surveys to explore the limitations of such a policy approach. The utility of problem reconstruction as a means of disrupting policy-informed evidence and the legitimisation of purported evidence-based policy is considered.