17 research outputs found
Using Design Interventions to Develop Communication Solutions for Integrated Pest Management
Iowa State University’s (ISU) Integrated Pest Management (IPM) program partnered with the ISU College of Design (COD) to use Design Thinking and other practical design methodologies and theories to identify and develop approaches to address IPM extension and communication issues. ISU IPM met with agriculture industry, program colleagues, and ISU COD faculty to discuss IPM-related needs in agriculture and to determine the program’s primary challenges. ISU COD faculty developed a two-semester course for undergraduate students, allocating various resources to solve these challenges. Undergraduates in the course, as the primary agents and problem solvers, developed various strategies the IPM program and its colleagues could implement. A model of interdisciplinary collaboration was developed, where design and science may function as equal partners in a design education setting. In our collaboration, the partners bought into a design-led process-based methodology that began with identifying IPM communication needs. This project resulted in unique design interventions to communicate IPM to stakeholders and the public, as well as created a model for interdisciplinary cooperation that can be exported to fields outside of agriculture and IPM
Evolution of cosmic string configurations
We extend and develop our previous work on the evolution of a network of
cosmic strings. The new treatment is based on an analysis of the probability
distribution of the end-to-end distance of a randomly chosen segment of
left-moving string of given length. The description involves three distinct
length scales: , related to the overall string density, , the
persistence length along the string, and , describing the small-scale
structure, which is an important feature of the numerical simulations that have
been done of this problem. An evolution equation is derived describing how the
distribution develops in time due to the combined effects of the universal
expansion, of intercommuting and loop formation, and of gravitational
radiation. With plausible assumptions about the unknown parameters in the
model, we confirm the conclusions of our previous study, that if gravitational
radiation and small-scale structure effects are neglected, the two dominant
length scales both scale in proportion to the horizon size. When the extra
effects are included, we find that while and grow,
initially does not. Eventually, however, it does appear to scale, at a much
lower level, due to the effects of gravitational back-reaction.Comment: 61 pages, requires RevTex v3.0, SUSSEX-TH-93/3-4,
IMPERIAL/TP/92-93/4
The evolution of a network of cosmic string loops
We set up and analyse a model for the non-equilibrium evolution of a network
of cosmic strings initially containing only loops and no infinite strings. Due
to this particular initial condition, our analytical approach differs
significantly from existing ones. We describe the average properties of the
network in terms of the distribution function n(l,t) dl, the average number of
loops per unit volume with physical length between l and l + dl at time t. The
dynamical processes which change the length of loops are then estimated and an
equation, which we call the `rate equation', is derived for (dn/dt). In a
non-expanding universe, the loops should reach the equilibrium distribution
predicted by string statistical mechanics. Analysis of the rate equation gives
results consistent with this. We then study the rate equation in an expanding
universe and suggest that three different final states are possible for the
evolving loop network, each of which may well be realised for some initial
conditions. If the initial energy density in loops in the radiation era is low,
then the loops rapidly disappear. For large initial energy densities, we expect
that either infinite strings are formed or that the loops tend towards a
scaling solution in the radiation era and then rapidly disappear in the matter
era. Such a scenario may be relevant given recent work highlighting the
problems with structure formation from the standard cosmic string scenario.Comment: LaTeX, 27 pages, 10 figures included as .eps file
Vancomycin-resistant Enterococci in Intensive Care Hospital Settings
Vancomycin-resistant enterococci (VRE) have recently emerged as a
nosocomial pathogen and present an increasing threat to the treatment
of severely ill patients in intensive-care hospital settings. We
outline results of a study of the epidemiology of VRE transmission in
ICUs and define a reproductive number R0; the number of secondary
colonization cases induced by a single VRE-colonized patient in a
VRE-free ICU, for VRE transmission. For VRE to become endemic requires
R0 >1. We estimate that in the absence of infection control measures
R0 lies in the range 3-4 in defined ICU settings. Once infection
control measures are included R0=0.6, suggesting that admission of
VRE-colonized patients can stabilize endemic VRE
Risk factors for the transmission of methicillin-resistant Staphylococcus aureus in an adult intensive care unit: fitting a model to the data
Little is known about the amount of cross-transmission, the risk factors for infection, and the relative effectiveness of infection control procedures when methicillin-resistant Staphylococcus aureus (MRSA) infection occurs at highly endemic levels in intensive care units. A cohort study was done to identify exposures associated with cases that likely were the result of cross-transmission (i.e., occurring in clusters and with indistinguishable MRSA macrorestriction profiles). Fitting a simple stochastic model to the ascertained data allowed prediction of the effectiveness of infection control measures. Exposure to relative staff deficit (adjusted rate ratio, 1.05 independent; 95% confidence interval, 1.02-1.09) was the only factor significantly associated with potential transmission (P =.001). It was predicted that a 12% improvement in adherence to hand-hygiene policies might have compensated for staff shortage and prevented transmission during periods of overcrowding, shared care, and high workload but that this would be hard to achieve