One of the most pressing issues in facing emerging and re-emerging respiratory infections is how to bring them under control with current public health measures. Approaches such as the Wells-Riley equation, competing-risks model, and Von Foerster equation are used to prioritize control-measure efforts. Here we formulate how to integrate those three different types of functional relationship to construct easy-to-use and easy-to-interpret critical-control lines that help determine optimally the intervention strategies for containing airborne infections. We show that a combination of assigned effective public health interventions and enhanced engineering control measures would have a high probability for containing airborne infection. We suggest that integrated analysis to enhance modelling the impact of potential control measures against airborne infections presents an opportunity to assess risks and benefits. We demonstrate the approach with examples of optimal control measures to prioritize respiratory infections of severe acute respiratory syndrome (SARS), influenza, measles, and chickenpox.
SUMMARYVaccination has proved a powerful defence against measles. We reappraise measles seroepidemiological data in Taiwan from 1974 to 2004 having robust age-stratified serological information on exposure and immunity to quantitatively characterize measles vaccination programmes. We dynamically model measles seroepidemiology to estimate age-dependent intensity of infection associated with the effects of different contact patterns on pre-and post-vaccination. The WAIFM (who acquires infection from whom) contact matrix is employed to describe the transmission between and within each age group. A deterministic SEIR (susceptible-exposed-infected-recovery) model is used to capture subpopulation dynamics. Our study shows that mass regional or nationwide vaccination programmes could greatly reduce the potential for a major measles epidemic and have strong direct effects on the potential impact of childhood vaccination. We parameterize a predictive model that should reduce the socio-economic costs of measles surveillance in Taiwan and thereby encourage its continuance, especially for preschool children.
The face-centered-tetragonal L1 0 FePt films with ͑001͒ preferred orientation has perpendicular coercivity ͑Hc Ќ ͒ of about 2462 Oe that can be achieved by stacking a structure of ͑FePt 4 nm/ Ag 2 nm͒ 5 multilayer films on the 5 nm thick MgO underlayer and annealing at 600°C for 30 min. It is found that both the perpendicular anisotropy and coercivity of ͑FePt 4 nm/ Ag 2 nm͒ 5 multilayer films are enhanced by introducing an Ag buffer layer ͑Ϲ20 nm͒ between the ͑FePt 4 nm/ Ag 2 nm͒ 5 films and the MgO underlayer. When introducing an Ag buffer layer of 20 nm thickness, the Hc Ќ value of the MgO 5 nm/ Ag 20 nm/ ͑FePt 4 nm/ Ag 2 nm͒ 5 multilayer films is observed to increase from 2462 to 4731 Oe, which has significant potential as perpendicular magnetic recording media for high-density recording.
͓͑FePt͒ 100Ϫx Cr x ͔ 100-␦ -͓SiN͔ ␦ nanocomposite thin films with xϭ0 -25 at. %, and ␦ ϭ0 -30 vol. % were fabricated on a natural-oxidized Si͑100͒ substrate by dc and rf magnetron cosputtering of FePt, Cr, and Si 3 N 4 targets. The thickness of the films was kept at 10 nm in order to examine the possibility for applying in high-density magnetic recording media. Transmission electron microscopy ͑TEM͒ and electron diffraction analyses indicated that the face-centered-cubic ͑fcc͒ ␥-phase FePt, body-centered-cubic ͑bcc͒ Cr, and amorphous SiN coexisted in as-deposited films. The as-deposited films were annealed in vacuum between 350 and 750°C for 30 min, and then ice-water quench cooling, in order to transform the soft magnetic fcc ␥-FePt phase to the hard magnetic face-centered-tetragonal ͑fct͒ ␥ 1 phase. Cr was added to inhibit the FePt grain growth, and was observed by TEM and energy disperse spectrum analysis in the grain surface area of FePt grains. The TEM observation indicated that the structure of the film was an amorphous SiN matrix with FePtCr particles dispersed in it. The particle size of FePtCr in annealed film was increased with the annealing temperature but decreased with the increase of SiN and Cr contents. Magnetization measurements indicated that the optimum condition for high-density magnetic recording purpose of the film was found with xϭ10 at. % and ␦ϭ15 vol. %, annealing at 600°C for 30 min. The average grain size of the FePtCr in this film is about 9.5 nm, the saturation magnetization is 450 emu/cm 3 , in-plane coercivity is 3.7 kOe, and in-plane squareness is about 0.75.
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