380 research outputs found
The net reproduction rate and the type-reproduction number in multiregional demography
No full textIn order to study effects of migration on demographic changes of multiregional populations, multiregional population modelling is a useful traditional tool. Although multiregional mathematical demography has been extensively explored since the beginning of the 1970s, its key concept, the multiregional net reproduction rate, has been long neglected. In this review, we focus on a multiregional stable population system and elaborate the definition of the multiregional net reproduction rate. Next we introduce the type-reproduction number from mathematical epidemiology and show that it becomes a useful index to formulate a simple control relation for a multiregional population. Mathematical ideas presented here will help us to reconsider multiregional mathematical demography, which is a useful theoretical framework to study effects of interregional migration on population dynamics and composition.
SPECTROSCOPIC REMOTE-SENSING OF MOLECULAR CONSTITUENTS IN THE ATMOSPHERE BY LASER-RADAR TECHNIQUES BASED ON OPTICAL SCATTERING PHENOMENA
No full textH. Inaba and T. Kobayasi, Nature, 224, 170, (1969). T. Kobayasi and H. Inaba, Appl. Phys. Letters, 17, 139, (1970). H. Inaba and T. Kobayasi. Invited paper to the Sixth International Quantum Electronics Conference, Kyoto, Japan, September 1970. T. Kobayasi and H. Inaba. Proceedings of IEEE., 58, 1568, (1970).""Author Institution: Research Institute of Electrical Communication, Tohoku UniversityThe usefulness of Raman spectroscopy, which is so far recognized as a complementary technique to infrared spectroscopy, can be extended to include various new fields which are unique to itself. The laser-Raman radar scheme detecting the Raman backscattered echoes has been and confirmed experimentally by the present , which is capable of measuring remotely the number density of molecular constituents as well as their species existing not only in the ordinary but also in the polluted atmosphere. This paper wishes to report the operational performance and the experimental results, so far obtained, of our laser-Raman radar as a completely single-ended system for the chemical analysis of the real atmosphere. An alternative method, which utilizes a frequency-tunable dye laser with high repetition rate of pulsed operation is also developed to investigate the resonance spectroscopic effects of a variety of molecules and atoms contained in the lower and upper atmosphere. These effects include the fluorescence and the resonance scatterings along with the resonance Raman scattering, and are expected to improve significantly the sensitivity and the range capability for the constituent analysis of our environmental air
The Basic Reproduction Number of an Infectious Disease in a Stable Populatio: The Impact of Population Growth Rate on the Eradication Threshold
No full textAlthough age-related heterogeneity of infection has been addressed in various epidemic models assuming a demographically stationary population,only a few studies have explicitly dealt with age-specfic patterns of transmission in growing or decreasing population. To discuss the threshold principl realistically,the present study investigates an age-duration-structured
SIR epidemic model assuminga a stable host population,as the first scheme to account for the non-stationality of the host population.
The basic reproduction number R0 is derived using the next generation perator,Permitting discussions over the well-known invasion principles.The condition of endemic steady state is also characterized by using the effective next generation operator. Subsequently,estimators of R0 are offered which can explicitly account for non-zero population growth rate. Critical coverages of vaccination are also shown,highlighting
the threshold condition for a population with varying size.When quantifying R0 using the force of infection estimated from serological date, it should be remembered that the estimate increases as the population growth rate decreases.On the contrary,given the same R0,critical coverage of vaccination in a growing population would be higher than that of decreasing population.Our exercise implies that high mass vaccination coverage at an early age would be needed to control childhood vaccine-preventable diseases in developing countries.
Although we here present only estimation formulae,the reader may refer to Inaba and Nisiura[11] for theoretical detail and numerical examples.departmental bulletin pape
Endemic Threshold Analysis for the Kermack-McKendrick Reinfection Model (Theory of Biomathematics and Its Applications XII : Mathematical and experimental approach to clarify patterns in a transition process)
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