149 research outputs found
Sex-specific spatio-temporal variability in reproductive success promotes the evolution of sex-biased dispersal
Abstract: Inbreeding depression, asymmetries in costs or benefits of dispersal, and the mating system have been identified as potential factors underlying the evolution of sex-biased dispersal. We use individual-based simulations to explore how the mating system and demographic stochasticity influence the evolution of sex-specific dispersal in a metapopulation with females competing over breeding sites, and males over mating opportunities. Comparison of simulation results for random mating with those for a harem system (locally, a single male sires all offspring) reveal that even extreme variance in local male reproductive success (extreme male competition) does not induce male-biased dispersal. The latter evolves if the between-parch variance in reproductive success is larger for males than females. This can emerge due to demographic stochasticity if the habitat patches are small. More generally, members of a group of individuals experiencing higher spatio-temporal variance in fitness expectations may evolve to disperse with greater probability than others
Good Fences: The Importance of Setting Boundaries for Peaceful Coexistence
We consider the conditions of peace and violence among ethnic groups, testing
a theory designed to predict the locations of violence and interventions that
can promote peace. Characterizing the model's success in predicting peace
requires examples where peace prevails despite diversity. Switzerland is
recognized as a country of peace, stability and prosperity. This is surprising
because of its linguistic and religious diversity that in other parts of the
world lead to conflict and violence. Here we analyze how peaceful stability is
maintained. Our analysis shows that peace does not depend on integrated
coexistence, but rather on well defined topographical and political boundaries
separating groups. Mountains and lakes are an important part of the boundaries
between sharply defined linguistic areas. Political canton and circle
(sub-canton) boundaries often separate religious groups. Where such boundaries
do not appear to be sufficient, we find that specific aspects of the population
distribution either guarantee sufficient separation or sufficient mixing to
inhibit intergroup violence according to the quantitative theory of conflict.
In exactly one region, a porous mountain range does not adequately separate
linguistic groups and violent conflict has led to the recent creation of the
canton of Jura. Our analysis supports the hypothesis that violence between
groups can be inhibited by physical and political boundaries. A similar
analysis of the area of the former Yugoslavia shows that during widespread
ethnic violence existing political boundaries did not coincide with the
boundaries of distinct groups, but peace prevailed in specific areas where they
did coincide. The success of peace in Switzerland may serve as a model to
resolve conflict in other ethnically diverse countries and regions of the
world.Comment: paper pages 1-14, 4 figures; appendices pages 15-43, 20 figure
Autonomous docking using direct optimal control
We propose a method for performing autonomous docking of marine vessels using
numerical optimal control. The task is framed as a dynamic positioning problem,
with the addition of spatial constraints that ensure collision avoidance. The
proposed method is an all-encompassing procedure for performing both docking,
maneuvering, dynamic positioning and control allocation. In addition, we show
that the method can be implemented as a real-time MPC-based algorithm on
simulation results of a supply vessel.Comment: 12th IFAC Conference on Control Applications in Marine Systems,
Robotics, and Vehicles (CAMS 2019). IFAC; Daejeon. 2019-09-18 - 2019-09-2
Combining system identification with reinforcement learning-based MPC
In this paper we propose and compare methods for combining system
identification (SYSID) and reinforcement learning (RL) in the context of
data-driven model predictive control (MPC). Assuming a known model structure of
the controlled system, and considering a parametric MPC, the proposed approach
simultaneously: a) Learns the parameters of the MPC using RL in order to
optimize performance, and b) fits the observed model behaviour using SYSID. Six
methods that avoid conflicts between the two optimization objectives are
proposed and evaluated using a simple linear system. Based on the simulation
results, hierarchical, parallel projection, nullspace projection, and singular
value projection achieved the best performance.Comment: Accepted to the IFAC202
Technology, resources and geography in a paradigm shift: the case of Critical & Conflict Materials in ICTs
The mining of several critical raw materials – including the so-called ‘conflict minerals’ associated with armed conflict and human rights abuses – and their combination, refining and use in many new advanced electronic products, are providing an important material infrastructure to current technological progress. Relying on text analysis of USPTO patent data between 1976 and 2017, our explorative study provides a methodological and empirical starting point for exploring the technological and geographical linkages between technological paradigms and selected critical and conflict materials (CCMs). Our descriptive analysis finds evidence of a clear association between ICT technologies and CCM intensity over time, and of a striking resource-technology divide in global ICT value chains between value creating and value extracting activities across Global North and Global South and their regions. The paperintends to emphasize the need for a more critical, spatially sensitive approach to studying resource-based technological change to expose the uneven development consequences created, sustained, or mitigated by technological progress
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