Hasil untuk "Reproduction"

W. Benjamin

One of the most important works of cultural theory ever written, Walter Benjamin's groundbreaking essay explores how the age of mass media means audiences can listen to or see a work of art repeatedly - and what the troubling social and political implications of this are. Throughout history, some books have changed the world. They have transformed the way we see ourselves - and each other. They have inspired debate, dissent, war and revolution. They have enlightened, outraged, provoked and comforted. They have enriched lives - and destroyed them. Now Penguin brings you the works of the great thinkers, pioneers, radicals and visionaries whose ideas shook civilization and helped make us who we are.

P. Bourdieu

R. Sussarellu, M. Suquet, Y. Thomas et al.

P. Delamater, Erica J. Street, Timothy F. Leslie et al.

The basic reproduction number (R0), also called the basic reproduction ratio or rate or the basic reproductive rate, is an epidemiologic metric used to describe the contagiousness or transmissibility of infectious agents. R0 is affected by numerous biological, sociobehavioral, and environmental factors that govern pathogen transmission and, therefore, is usually estimated with various types of complex mathematical models, which make R0 easily misrepresented, misinterpreted, and misapplied. R0 is not a biological constant for a pathogen, a rate over time, or a measure of disease severity, and R0 cannot be modified through vaccination campaigns. R0 is rarely measured directly, and modeled R0 values are dependent on model structures and assumptions. Some R0 values reported in the scientific literature are likely obsolete. R0 must be estimated, reported, and applied with great caution because this basic metric is far from simple.

A. Cori, N. Ferguson, C. Fraser et al.

Abstract The quantification of transmissibility during epidemics is essential to designing and adjusting public health responses. Transmissibility can be measured by the reproduction number R, the average number of secondary cases caused by an infected individual. Several methods have been proposed to estimate R over the course of an epidemic; however, they are usually difficult to implement for people without a strong background in statistical modeling. Here, we present a ready-to-use tool for estimating R from incidence time series, which is implemented in popular software including Microsoft Excel (Microsoft Corporation, Redmond, Washington). This tool produces novel, statistically robust analytical estimates of R and incorporates uncertainty in the distribution of the serial interval (the time between the onset of symptoms in a primary case and the onset of symptoms in secondary cases). We applied the method to 5 historical outbreaks; the resulting estimates of R are consistent with those presented in the literature. This tool should help epidemiologists quantify temporal changes in the transmission intensity of future epidemics by using surveillance data.

P. van den Driessche

This primer article focuses on the basic reproduction number, ℛ0, for infectious diseases, and other reproduction numbers related to ℛ0 that are useful in guiding control strategies. Beginning with a simple population model, the concept is developed for a threshold value of ℛ0 determining whether or not the disease dies out. The next generation matrix method of calculating ℛ0 in a compartmental model is described and illustrated. To address control strategies, type and target reproduction numbers are defined, as well as sensitivity and elasticity indices. These theoretical ideas are then applied to models that are formulated for West Nile virus in birds (a vector-borne disease), cholera in humans (a disease with two transmission pathways), anthrax in animals (a disease that can be spread by dead carcasses and spores), and Zika in humans (spread by mosquitoes and sexual contacts). Some parameter values from literature data are used to illustrate the results. Finally, references for other ways to calculate ℛ0 are given. These are useful for more complicated models that, for example, take account of variations in environmental fluctuation or stochasticity.

P. van den Driessche, James Watmough

P. Bourdieu, J. Passeron

O. Diekmann, J. Heesterbeek, J. Metz

N. Chodorow

E. Knobil, J. D. Neill

G. Williams

E. Reinhard, Michael M. Stark, P. Shirley et al.

A. Clements

F. Guerra, S. Bolotin, G. Lim et al.

Susan Bordo

The preparation of stable aqueous latices from solvent dispersions of elastomers and other high polymer compositions has presented problems including excessive viscosity during processing and foaming, which have produced losses and increased costs. Herein combinations of steps are disclosed which reduce or eliminate various of these problems and enable the preparation of stable latices of high solids content. The process in common with that of related copending applications is characterized, inter alia, by the establishment of a flow of steam as a continuous phase into which an emulsion of a cement of the polymer is dispersed as an aerosol of latex droplets in a solvent-vapor continuum, followed by coalescence of the latex droplets and separation of the resulting coalesced liquid phase from the resulting solvent-vapor phase. In one embodiment of the present method an aqueous emulsion is prepared the dispersed phase of which principally comprises particles of precursor latex particle size and which may contain a lesser proportion of particles of greater than precursor latex particle size. This emulsion is converted to a stable latex by subjecting the same to special conditions which cause selective agglomeration of the particles of greater than precursor latex particle size, and removing the so agglomerated particles to yield a latex essentially free of particles of greater than colloidal size.

Tao Zhou, Quanhui Liu, Z. Yang et al.

To estimate the basic reproduction number of the Wuhan novel coronavirus (2019‐nCoV).

J. Amis, J. Mair, K. Munir

With societal inequalities continuing to increase and organizations providing the vast majority of people with their income, we wanted to assess the ways in which organizational practices are impli...

Chayu Yang, Jin Wang

We consider a class of k-dimensional reaction-diffusion epidemic models (k=1,2,⋯) that are developed from autonomous ODE systems. We present a computational approach for the calculation and analysis of their basic reproduction numbers. Particularly, we apply matrix theory to study the relationship between the basic reproduction numbers of the PDE models and those of their underlying ODE models. We show that the basic reproduction numbers are the same for these PDE models and their associated ODE models in several important scenarios. We additionally provide two numerical examples to verify our analytical results.

The purpose of this American Society for Reproductive Medicine Practice Committee report is to provide clinicians with principles and strategies for the evaluation and treatment of couples with infertility associated with obesity. This revised document replaces the Practice Committee document titled "Obesity and reproduction: an educational bulletin" last published in 2015 (Fertil Steril 2015;104:1116-26).