2,305 research outputs found
A Partially Reflecting Random Walk on Spheres Algorithm for Electrical Impedance Tomography
In this work, we develop a probabilistic estimator for the voltage-to-current
map arising in electrical impedance tomography. This novel so-called partially
reflecting random walk on spheres estimator enables Monte Carlo methods to
compute the voltage-to-current map in an embarrassingly parallel manner, which
is an important issue with regard to the corresponding inverse problem. Our
method uses the well-known random walk on spheres algorithm inside subdomains
where the diffusion coefficient is constant and employs replacement techniques
motivated by finite difference discretization to deal with both mixed boundary
conditions and interface transmission conditions. We analyze the global bias
and the variance of the new estimator both theoretically and experimentally. In
a second step, the variance is considerably reduced via a novel control variate
conditional sampling technique
Socio-economic impacts of alternative GIN control practices. Project deliverable 11 (WP4)
This report is a deliverable (WP4) from the EU-funded PrOPara project. The PrOPara project aspires to i) assess existing knowledge from research, development and benchmarking studies on alternatives to parasite control on organic ruminant farms, ii) collecting novel data on disease prevalence, risk assessment analysis and parasite control measures, through monitoring (farm surveys and stakeholder participation studies), iii) performing cost-benefit analysis on alternative parasite control measures and iv) developing and delivering technical innovation to facilitate implementation of sustainable parasite control strategies.
A combined approach of modelling and focus groups for feedback was employed to assess the economic impacts of alternative GIN control strategies in South West France and North East Scotland. This two step method allowed results from the survey and farm modelling to be used during workshops, which also addressed social factors explaining the uptake and acceptance of GIN practices to control parasites.
An existing excel based farm model was adapted in order to estimate the economic impacts of a range of alternative GIN practices. The model was adapted using data from a typical farm for organic goat system in France (Occitanie and Auvergne-Rhône-Alpes Regions) and two organic sheep systems (lowland and upland) in Scotland.
A structured workshop approach was utilised to address both the social and economic factors related to adoption of alternative GIN practices by farmers. To this purpose, we adapted the Structured Decision Making (SDM) approach commonly used for decisions taking (Gregory and Keeney 1994, Conroy, Barker et al. 2008, Ogden and Innes 2009, Gregory 2012, Johnson, Eaton et al. 2015, Fatorić and Seekamp 2017).
Overall, the modelling and farmer feedback showed that control of GIN needs to be farm specific, to suit the individual characteristics of both the farm but also the beliefs of the farmer. The extension of withdrawal periods combined with resistance issues in France have led to the adoption of TST by some farmers, but others are less convinced of its efficiency. The farmers in Scotland seem to have adopted multiple strategies such as use of arable land and mixed grazing to keep GIN levels from severely affecting their profits. However, the diversity of opinions and calls by the French farmers in particular for more trials, shows there is still further work to understand this problem and develop more effective, sustainable solutions
PrOPara project workshop Focus Group Manual: Step-wise Approach (Project deliverable 10.(WP4))
This handbook is a deliverable (WP4) from the EU-funded PrOPara project. The PrOPara project aspires to i) assess existing knowledge from research, development and benchmarking studies on alternatives to parasite control on organic ruminant farms, ii) collecting novel data on disease prevalence, risk assessment analysis and parasite control measures, through monitoring (farm surveys and stakeholder participation studies), iii) performing cost-benefit analysis on alternative parasite control measures and iv) developing and delivering technical innovation to facilitate implementation of sustainable parasite control strategies.
This handbook serves as a baseline to conduct workshops with stakeholders in France and Scotland. It provides the organisers with a structured approach on 8 steps. The implementation of this approach will allow identification of main alternative GIN practices according to stakeholders’ views, as well as analysing economic impacts and reasons for adopting them or not
On Disjoint hypercubes in Fibonacci cubes
The {\em Fibonacci cube} of dimension , denoted as , is the
subgraph of -cube induced by vertices with no consecutive 1's. We
study the maximum number of disjoint subgraphs in isomorphic to
, and denote this number by . We prove several recursive results
for , in particular we prove that . We also prove a closed formula in which is given in
terms of Fibonacci numbers, and finally we give the generating function for the
sequence
Investigating Performance and Usage of Input Methods for Soft Keyboard Hotkeys
Touch-based devices, despite their mainstream availability, do not support a
unified and efficient command selection mechanism, available on every platform
and application. We advocate that hotkeys, conventionally used as a shortcut
mechanism on desktop computers, could be generalized as a command selection
mechanism for touch-based devices, even for keyboard-less applications. In this
paper, we investigate the performance and usage of soft keyboard shortcuts or
hotkeys (abbreviated SoftCuts) through two studies comparing different input
methods across sitting, standing and walking conditions. Our results suggest
that SoftCuts not only are appreciated by participants but also support rapid
command selection with different devices and hand configurations. We also did
not find evidence that walking deters their performance when using the Once
input method.Comment: 17+2 pages, published at Mobile HCI 202
A New Game Invariant of Graphs: the Game Distinguishing Number
The distinguishing number of a graph is a symmetry related graph
invariant whose study started two decades ago. The distinguishing number
is the least integer such that has a -distinguishing coloring. A
distinguishing -coloring is a coloring
invariant only under the trivial automorphism. In this paper, we introduce a
game variant of the distinguishing number. The distinguishing game is a game
with two players, the Gentle and the Rascal, with antagonist goals. This game
is played on a graph with a set of colors. Alternately,
the two players choose a vertex of and color it with one of the colors.
The game ends when all the vertices have been colored. Then the Gentle wins if
the coloring is distinguishing and the Rascal wins otherwise. This game leads
to define two new invariants for a graph , which are the minimum numbers of
colors needed to ensure that the Gentle has a winning strategy, depending on
who starts. These invariants could be infinite, thus we start by giving
sufficient conditions to have infinite game distinguishing numbers. We also
show that for graphs with cyclic automorphisms group of prime odd order, both
game invariants are finite. After that, we define a class of graphs, the
involutive graphs, for which the game distinguishing number can be
quadratically bounded above by the classical distinguishing number. The
definition of this class is closely related to imprimitive actions whose blocks
have size . Then, we apply results on involutive graphs to compute the exact
value of these invariants for hypercubes and even cycles. Finally, we study odd
cycles, for which we are able to compute the exact value when their order is
not prime. In the prime order case, we give an upper bound of
Optimal accessing and non-accessing structures for graph protocols
An accessing set in a graph is a subset B of vertices such that there exists
D subset of B, such that each vertex of V\B has an even number of neighbors in
D. In this paper, we introduce new bounds on the minimal size kappa'(G) of an
accessing set, and on the maximal size kappa(G) of a non-accessing set of a
graph G. We show strong connections with perfect codes and give explicitly
kappa(G) and kappa'(G) for several families of graphs. Finally, we show that
the corresponding decision problems are NP-Complete
Complexity of Manipulating Sequential Allocation
Sequential allocation is a simple allocation mechanism in which agents are
given pre-specified turns and each agents gets the most preferred item that is
still available. It has long been known that sequential allocation is not
strategyproof.
Bouveret and Lang (2014) presented a polynomial-time algorithm to compute a
best response of an agent with respect to additively separable utilities and
claimed that (1) their algorithm correctly finds a best response, and (2) each
best response results in the same allocation for the manipulator. We show that
both claims are false via an example. We then show that in fact the problem of
computing a best response is NP-complete. On the other hand, the insights and
results of Bouveret and Lang (2014) for the case of two agents still hold
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