Adaptive age replacement

Bayesian approach to adaptive age replacement treated by dynamic programmin

Understanding Teacher Well-Being During the Covid-19 Pandemic Over Time: A Qualitative Longitudinal Study

Teacher stress and burnout under non-crisis situations are well-documented challenges. However, during COVID-19, teachers have faced new and unexpected stressors, potentially contributing to rising burnout and attrition. Yet many teachers have also demonstrated great resilience and found effective ways to manage their well-being. To explore teacher well-being during COVID-19, this study used a longitudinal qualitative design that employed recurrent cross-sectional analysis using wo conceptual frameworks including the job-demands-resource model of well-being and the hierarchy of needs theory of motivation. Researchers investigated 25 teacher’s well-being during COVID-19 at two time points (June 2020 and March 2021). Both barriers and facilitators of well-being at the individual and contextual levels are discussed

Picoliter-volume inkjet printing into planar microdevice reservoirs for low-waste, high-capacity drug loading.

Oral delivery of therapeutics is the preferred route for systemic drug administration due to ease of access and improved patient compliance. However, many therapeutics suffer from low oral bioavailability due to low pH and enzymatic conditions, poor cellular permeability, and low residence time. Microfabrication techniques have been used to create planar, asymmetric microdevices for oral drug delivery to address these limitations. The geometry of these microdevices facilitates prolonged drug exposure with unidirectional release of drug toward gastrointestinal epithelium. While these devices have significantly enhanced drug permeability in vitro and in vivo, loading drug into the micron-scale reservoirs of the devices in a low-waste, high-capacity manner remains challenging. Here, we use picoliter-volume inkjet printing to load topotecan and insulin into planar microdevices efficiently. Following a simple surface functionalization step, drug solution can be spotted into the microdevice reservoir. We show that relatively high capacities of both topotecan and insulin can be loaded into microdevices in a rapid, automated process with little to no drug waste

Structure and morphology of nanocomposites

Since the pioneering work on nylon/clay nanocotnposites performed by Toyota in the early 1990's, where improvements in mechanical properties of the nylon polymer were reported, there has been a great deal of research focussed on blends of thermoplastic polymers and nanoparticles. However, there has been relatively little work exploring the incorporation of nanoparticles into thermosetting polymers. Of the work that has been conducted, full exfoliation, or separation of the nanoparticles required for mechanical and fire retardancy property enhancements, has been very difficult to achieve. Low resin viscosity and the application of ultrasonic vibration are known to be key factors in facilitating exfoliation in thermosetting nanocomposites. The Quickstep process is an out-of autoclave technique that utilises balanced pressure and liquid heating and cooling to cure composite components. As a result, cure cycle times are reduced, from several hours to just a few minutes. The Quickstep process is a recent Australian innovation and there are currently three Quickstep plants worldwide, located at Deakin University, Toyota, Japan and the University of Manchester, UK. Quickstep Technology has the potential to produce commercially ready thermosetting nanocomposites, by curing the matrix together with the nano-clay particles. The combination of rapid temperature ramp rates, leading to low resin viscosity, and the use of vibration through the fluid filled bladder, give the process a unique approach to manufacturing these materials. Results from sample characterisation and mechanical tests will be presented, to compare the mechanical properties of the thermoset nanocomposites to conventional composites. These mechanical properties will be correlated with various morphologies produced by modifying the processing parameters

Magnetodielectric coupling in Mn3O4

We have investigated the dielectric anomalies associated with spin ordering transitions in the tetragonal spinel Mn$_3$O$_4$, using thermodynamic, magnetic, and dielectric measurements. We find that two of the three magnetic ordering transitions in Mn$_3$O$_4$ lead to decreases in the temperature dependent dielectric constant at zero applied field. Applying a magnetic field to the polycrystalline sample leaves these two dielectric anomalies practically unchanged, but leads to an increase in the dielectric constant at the intermediate spin-ordering transition. We discuss possible origins for this magnetodielectric behavior in terms of spin-phonon coupling. Band structure calculations suggest that in its ferrimagnetic state, Mn$_3$O$_4$ corresponds to a semiconductor with no orbital degeneracy due to strong Jahn-Teller distortion.Comment: 6 pages, 7 figure

Anthropic Explanation of the Dark Matter Abundance

I use Bousso's causal diamond measure to make a statistical prediction for the dark matter abundance, assuming an axion with a large decay constant f_a >> 10^{12} GeV. Using a crude approximation for observer formation, the prediction agrees well with observation: 30% of observers form in regions with less dark matter than we observe, while 70% of observers form in regions with more dark matter. Large values of the dark matter ratio are disfavored by an elementary effect: increasing the amount of dark matter while holding fixed the baryon to photon ratio decreases the number of baryons inside one horizon volume. Thus the prediction is rather insensitive to assumptions about observer formation in universes with much more dark matter than our own. The key assumption is that the number of observers per baryon is roughly independent of the dark matter ratio for ratios near the observed value.Comment: 10 pages; v3: published version, references adde

Calibration of a compact survey probe for pitot pressure, Mach number, and flow angularity measurements

Calibration of compact survey probe for pitot pressure, Mach number, and flow angularity measurement

Electric-field control of magnetic ordering in the tetragonal BiFeO3

We propose a way to use electric-field to control the magnetic ordering of the tetragonal BiFeO3. Based on systematic first-principles studies of the epitaxial strain effect on the ferroelectric and magnetic properties of the tetragonal BiFeO3, we find that there exists a transition from C-type to G-type antiferromagnetic (AFM) phase at in-plane constant a ~ 3.905 {\AA} when the ferroelectric polarization is along [001] direction. Such magnetic phase transition can be explained by the competition between the Heisenberg exchange constant J1c and J2c under the influence of biaxial strain. Interestingly, when the in-plane lattice constant enlarges, the preferred ferroelectric polarization tends to be canted and eventually lies in the plane (along [110] direction). It is found that the orientation change of ferroelectric polarization, which can be realized by applying external electric-field, has significant impact on the Heisenberg exchange parameters and therefore the magnetic orderings of tetragonal BiFeO3. For example, at a ~ 3.79 {\AA}, an electric field along [111] direction with magnitude of 2 MV/cm could change the magnetic ordering from C-AFM to G-AFM. As the magnetic ordering affects many physical properties of the magnetic material, e.g. magnetoresistance, we expect such strategy would provide a new avenue to the application of multiferroic materials.Comment: 4 pages, 4 figure