4,076 research outputs found
How Sustainable is Organic Agriculture?
Dan Anderson - UIUC Dept. of Natural Resources and Environmental Sciences.
For some time now, organic food has been one of the fastest growing segments of the food industry, growing at a rate of about 20% annually for the last 10 years. Those who purchase organic food do so for a variety of reasons - flavor, health, environmental and social. Critics claim that organic food is for an elite, high-income customer base, willing to spend more for food they falsely believe is better. Furthermore, critics claim that organic farming is not productive enough to meet the growing food challenges of a 6 billion plus world population. They also contend there is no evidence that organic food is healthier than food produced by conventional, chemical-intensive methods. Recent research provides evidence that organic food is healthier and that organic farming is often as productive as conventional farming. This presentation will explore how sustainable organic and natural farming methods are for farmer, consumers and the environment
How Algorithmic Confounding in Recommendation Systems Increases Homogeneity and Decreases Utility
Recommendation systems are ubiquitous and impact many domains; they have the
potential to influence product consumption, individuals' perceptions of the
world, and life-altering decisions. These systems are often evaluated or
trained with data from users already exposed to algorithmic recommendations;
this creates a pernicious feedback loop. Using simulations, we demonstrate how
using data confounded in this way homogenizes user behavior without increasing
utility
Nonlinear Bessel beams
The effect of the Kerr nonlinearity on linear non-diffractive Bessel beams is
investigated analytically and numerically using the nonlinear Schr\"odinger
equation. The nonlinearity is shown to primarily affect the central parts of
the Bessel beam, giving rise to radial compression or decompression depending
on whether the nonlinearity is focusing or defocusing, respectively. The
dynamical properties of Gaussian-truncated Bessel beams are also analysed in
the presence of a Kerr nonlinearity. It is found that although a condition for
width balance in the root-mean-square sense exists, the beam profile becomes
strongly deformed during propagation and may exhibit the phenomena of global
and partial collapse.Comment: 15 pages, 7 figure
Buk bilong Pikinini Literacy Program Evaluation 2018: Evaluation Report
Buk bilong Pikinini (BbP) provides access to early childhood education and care (ECEC) programs with a specific focus on English language literacy for children from vulnerable communities in Papua New Guinea. This is highly relevant, given the fact that there is likely an over-representation of illiteracy in disadvantaged households and few opportunities for children within those households to be ready for a school system with English as the language of instruction. Established in 2007, BbP has been in operation for more than 10 years and has opened 17 library sites in that time. This evaluation provides evidence about the likely effectiveness of the programs relative to best practice and in the early childhood and school policy and program delivery context of PNG. The major methods used were literature review and critical review of BbP documentation, and stakeholder consultations, semi-structured interviews and observations of classrooms
Epidemic Variability in Hierarchical Geographical Networks with Human Activity Patterns
Recently, some studies have revealed that non-Poissonian statistics of human
behaviors stem from the hierarchical geographical network structure. On this
view, we focus on epidemic spreading in the hierarchical geographical networks,
and study how two distinct contact patterns (i. e., homogeneous time delay
(HOTD) and heterogeneous time delay (HETD) associated with geographical
distance) influence the spreading speed and the variability of outbreaks. We
find that, compared with HOTD and null model, correlations between time delay
and network hierarchy in HETD remarkably slow down epidemic spreading, and
result in a upward cascading multi-modal phenomenon. Proportionately, the
variability of outbreaks in HETD has the lower value, but several comparable
peaks for a long time, which makes the long-term prediction of epidemic
spreading hard. When a seed (i. e., the initial infected node) is from the high
layers of networks, epidemic spreading is remarkably promoted. Interestingly,
distinct trends of variabilities in two contact patterns emerge: high-layer
seeds in HOTD result in the lower variabilities, the case of HETD is opposite.
More importantly, the variabilities of high-layer seeds in HETD are much
greater than that in HOTD, which implies the unpredictability of epidemic
spreading in hierarchical geographical networks
The Relation of Thermal Fluctuation and Information-Entropy for One-Dimensional Rindler Oscillator
Within the framework of thermo-field-dynamics (TFD), the
information-entropies associated with the measurements of position and momentum
for one-dimensional Rindler oscillator are derived, and the connection between
its information-entropy and thermal fluctuation is obtained. A conclusion is
drawn that the thermal fluctuation leads to the loss of information.Comment: 14 pages, 1 figur
Integrability and Conservation Laws for the Nonlinear Evolution Equations of Partially Coherent Waves in Noninstantaneous Kerr Media
It is shown that the evolution equations describing partially coherent wave propagation in noninstantaneous Kerr media are integrable and have an infinite number of invariants. A recursion relation for generating these invariants is presented, and it is demonstrated how to express them in the coherent density, self-consistent multimode, mutual coherence, and Wigner formalisms
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