2,954 research outputs found
BIOMONITORING OF ECOLOGICAL STATE OF THE ENVIRONMENT IN THE ZONE OF INFLUENCE OF THE “CHERVONOGRADSKA” MINE OF THE LVIV-VOLYN COALFIELD
Coal mining has a very negative impact on the environment and it requires monitoring
studies to assess the degree of environmental pollution
Names as legacy: Catalogue of taxa described by and for Michel Brancucci (1950-2012)
This article provides a compilation of the taxa introduced to science by the late Dr. MichelBrancucci, Basel, and of the taxa named in honour of him. We provide details of nomenclatorial value such asholotype depository (for species described by Michel Brancucci), page number of the original description andtype locality. References of the original descriptions are given in full and the actual publication dates werethoroughly checked. Indices to all taxa complete this article and make it a searchable catalogue
Agent-Based Demand-Modeling Framework for Large-Scale Microsimulations
Microsimulation is becoming increasingly important in traffic demand modeling. The major advantage over traditional four-step models is the ability to simulate each traveler individually. Decision-making processes can be included for each individual. Traffic demand is the result of the different decisions made by individuals; these decisions lead to plans that the individuals then try to optimize. Therefore, such microsimulation models need appropriate initial demand patterns for all given individuals. The challenge is to create individual demand patterns out of general input data. In practice, there is a large variety of input data, which can differ in quality, spatial resolution, purpose, and other characteristics. The challenge for a flexible demand-modeling framework is to combine the various data types to produce individual demand patterns. In addition, the modeling framework has to define precise interfaces to provide portability to other models, programs, and frameworks, and it should be suitable for large-scale applications that use many millions of individuals. Because the model has to be adaptable to the given input data, the framework needs to be easily extensible with new algorithms and models. The presented demand-modeling framework for large-scale scenarios fulfils all these requirements. By modeling the demand for two different scenarios (Zurich, Switzerland, and the German states of Berlin and Brandenburg), the framework shows its flexibility in aspects of diverse input data, interfaces to third-party products, spatial resolution, and last but not least, the modeling process itself
Mobility traces and spreading of COVID-19
We use human mobility models, for which we are experts, and attach a virus infection dynamics to it, for which we are not experts but have taken it from the literature, including recent publications. This results in a virus spreading dynamics model. The results should be verified, but because of the current time pressure, we publish them in their current state. Recommendations for improvement are welcome. We come to the following conclusions:
1. Complete lockdown works. About 10 days after lockdown, the infection dynamics dies down. This assumes that lockdown is complete, which can be guaranteed in the simulation, but not in reality. Still, it gives strong support to the argument that it is never too late for complete lockdown.
2. As a rule of thumb, we would suggest complete lockdown no later than once 10% of hospital capacities available for COVID-19 are in use, and possibly much earlier. This is based on the following insights:
a. Even after lockdown, the infection dynamics continues at home, leading to another tripling of the cases before the dynamics is slowed.
b. There will be many critical cases coming from people who were infected before lockdown. Because of the exponential growth dynamics, their number will be large.
c. Researchers with more detailed disease progression models should improve upon these statements.
3. Our simulations say that complete removal of infections at child care, primary schools, workplaces and during leisure activities will not be enough to sufficiently slow down the infection dynamics. It would have been better, but still not sufficient, if initiated earlier.
4. Infections in public transport play an important role. In the simulations shown later, removing infections in the public transport system reduces the infection speed and the height of the peak by approximately 20%. Evidently, this depends on the infection parameters, which are not well known. – This does not point to reducing public transport capacities as a reaction to the reduced demand, but rather use it for lower densities of passengers and thus reduced infection rates.
5. In our simulations, removal of infections at child care, primary schools, workplaces, leisure activities, and in public transport may barely have been sufficient to control the infection dynamics if implemented early on. Now according to our simulations it is too late for this, and (even) harsher measures will have to be initiated until possibly a return to such a restrictive, but still somewhat functional regime will again be possible.
Evidently, all of these results have to be taken with care. They are based on preliminary infection parameters taken from the literature, used inside a model that has more transport/movement details than all others that we are aware of but still not enough to describe all aspects of reality, and suffer from having to write computer code under time pressure. Optimally, they should be confirmed independently. Short of that, given current knowledge we believe that they provide justification for “complete lockdown” at the latest when about 10% of available hospital capacities for COVID-19 are in use (and possibly earlier; we are no experts of hospital capabilities).
What was not investigated in detail in our simulations was contact tracing, i.e. tracking down the infection chains and moving all people along infection chains into quarantine. The case of Singapore has so far shown that this may be successful. Preliminary simulation of that tactic shows that it is difficult to implement for COVID-19, since the incubation time is rather long, people are contagious before they feel sick, or maybe never feel sufficiently sick at all. We will investigate in future work if and how contact tracing can be used together with a restrictive, but not totally locked down regime.
When opening up after lockdown, it would be important to know the true fraction of people who are already immune, since that would slow down the infection dynamics by itself. For Wuhan, the currently available numbers report that only about 0.1% of the population was infected, which would be very far away from “herd immunity”. However, there have been and still may be many unknown infections (Frankfurter Allgemeine Zeitung GmbH 2020)
Patterns in Illinois Educational School Data
We examine Illinois educational data from standardized exams and analyze
primary factors affecting the achievement of public school students. We focus
on the simplest possible models: representation of data through visualizations
and regressions on single variables. Exam scores are shown to depend on school
type, location, and poverty concentration. For most schools in Illinois,
student test scores decline linearly with poverty concentration. However
Chicago must be treated separately. Selective schools in Chicago, as well as
some traditional and charter schools, deviate from this pattern based on
poverty. For any poverty level, Chicago schools perform better than those in
the rest of Illinois. Selective programs for gifted students show high
performance at each grade level, most notably at the high school level, when
compared to other Illinois school types. The case of Chicago charter schools is
more complex. In the last six years, their students' scores overtook those of
students in traditional Chicago high schools.Comment: 9 pages, 6 figure
Disorder effects in cellular automata for two-lane traffic
For single-lane traffic models it is well known that particle disorder leads
to platoon formation at low densities. Here we discuss the effect of slow cars
in two-lane systems. Surprisingly, even a small number of slow cars can
initiate the formation of platoons at low densities. The robustness of this
phenomenon is investigated for different variants of the lane-changing rules as
well as for different variants on the single-lane dynamics. It is shown that
anticipation of drivers reduces the influence of slow cars drastically.Comment: RevTeX, 22 eps-figures included, 10 page
Preliminary Results of a Multiagent Traffic Simulation for Berlin
This paper provides an introduction to multi-agent traffic simulation. Metropolitan regions can consist of several million inhabitants, implying the simulation of several million travelers, which represents a considerable computational challenge. We reports on our recent case study of a real-world Berlin scenario. The paper explains computational techniques necessary to achieve results. It turns out that the difficulties there, because of data availability and because of the special situation of Berlin after the re-unification, are considerably larger than in previous scenarios that we have treated
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