725 research outputs found
Statistical theory of quasi stationary states beyond the single water-bag case study
An analytical solution for the out-of-equilibrium quasi-stationary states of
the paradigmatic Hamiltonian Mean Field (HMF) model can be obtained from a
maximum entropy principle. The theory has been so far tested with reference to
a specific class of initial condition, the so called (single-level) water-bag
type. In this paper a step forward is taken by considering an arbitrary number
of overlapping water bags. The theory is benchmarked to direct microcanonical
simulations performed for the case of a two-levels water-bag. The comparison is
shown to return an excellent agreement
CNVScan: detecting border- line copy number variations in NGS data via scan statistics
Background. Next Generation Sequencing (NGS) data has been extensively exploited in the last decade to analyse genome variations and to understand the role of genome variations in complex diseases. Copy number variations (CNVs) are genomic structural variants estimated to account for about 1.2% of the total variation in humans. CNVs in coding or regulatory regions may have an impact on the gene expression, often also at a functional level, and contribute to cause different diseases like cancer, autism and cardiovascular diseases. Computational methods developed for detection of CNVs from NGS data and based on the depth of coverage are limited to the identification of medium/large events and heavily influenced by the level of coverage. Result. In this paper we propose, CNVScan a CNV detection method based on scan statistics that overcomes limitations of previous read count (RC) based approaches mainly by being a window-less approach. The scans statistics have been used before mainly in epidemiology and ecology studies, but never before was applied to the CNV detection problem to the best of our knowledge. Since we avoid window- ing we do not have to choose an optimal window-size which is a key step in many previous approaches. Extensive simulated experiments with single read data in extreme situations (low coverage, short reads, homo/heterozygoticity) show that this approach is very effective for a range of small CNV (200-500 bp) for which previous state-of-the-art methods are not suitable. Conclusion. The scan statistics technique is applied and adapted in this paper for the first time to the CNV detection problem. Comparison with state-of-the art methods shows the approach is quite effective in discovering shortCNVin rather extreme situations in which previous methods fail or have degraded performance. CNVScan thus extends the range of CNV sizes and types that can be detected via read count with single read data
Traumatic myiasis in farmed animals caused by Wohlfahrtia magnifica in southern Italy (Diptera: Sarcophagidae)
Ten herds of sheep and goats (455 heads) were inspected for the presence of traumatic myiasis between May and September 2013 in the province of Cosenza, Calabria, southern Italy. Nine cases were discovered in sheep, goats and a sheepdog. Infested body sites included external genitalia, wounds (sheep and sheepdog) and hooves (goats). Larvae were removed from the infested body areas and reared to adult stage in the laboratory. Both the larvae and the adults were identified as belonging to the Mediterranean screwworm fly Wohlfahrtia magnifica (Schiner, 1862) (Diptera: Sarcophagidae), an obligatory parasite of humans and warm-blooded vertebrates. To our knowledge, these are the first cases of wohlfahrtiosis in sheep and goats to be reported from Calabria. The infested animals were living outdoors in spring and summer, and enclosed in sheds during the autumn and winter months. Observed effects of the myiases included severely impeded walking and tissue damage. Wohlfahrtiosis can cause significant economic loss to farmers. Data about the local distribution, seasonality and types of infestation caused by W. magnifica are useful to farmers and vets to improve control systems, in Calabria as elsewhere within the distributional range of the species.The file attached is the publishes (publishers PDF) version of the article. Open Access journal
Out of Equilibrium Solutions in the -Hamiltonian Mean Field model
Out of equilibrium magnetised solutions of the -Hamiltonian Mean Field
(-HMF) model are build using an ensemble of integrable uncoupled pendula.
Using these solutions we display an out-of equilibrium phase transition using a
specific reduced set of the magnetised solutions
Sticky islands in stochastic webs and anomalous chaotic cross-field particle transport by ExB electron drift instability
The ExB electron drift instability, present in many plasma devices, is an
important agent in cross-field particle transport. In presence of a resulting
low frequency electrostatic wave, the motion of a charged particle becomes
chaotic and generates a stochastic web in phase space. We define a scaling
exponent to characterise transport in phase space and we show that the
transport is anomalous, of super-diffusive type. Given the values of the model
parameters, the trajectories stick to different kinds of islands in phase
space, and their different sticking time power-law statistics generate
successive regimes of the super-diffusive transport.Comment: This manuscript contains 13 Pages and 21 figure
Stabilizing the intensity for a Hamiltonian model of the FEL
The intensity of an electromagnetic wave interacting self-consistently with a
beam of charged particles, as in a Free Electron Laser, displays large
oscillations due to an aggregate of particles, called the macro-particle. In
this article, we propose a strategy to stabilize the intensity by destabilizing
the macro-particle. This strategy involves the study of the linear stability of
a specific periodic orbit of a mean-field model. As a control parameter - the
amplitude of an external wave - is varied, a bifurcation occur in the system
which has drastic effects on the self-consistent dynamics, and in particular,
on the macro-particle. We show how to obtain an appropriate tuning of the
control parameter which is able to strongly decrease the oscillations of the
intensity without reducing its mean-value
Anomalous transport in Charney-Hasegawa-Mima flows
Transport properties of particles evolving in a system governed by the
Charney-Hasegawa-Mima equation are investigated. Transport is found to be
anomalous with a non linear evolution of the second moments with time. The
origin of this anomaly is traced back to the presence of chaotic jets within
the flow. All characteristic transport exponents have a similar value around
, which is also the one found for simple point vortex flows in the
literature, indicating some kind of universality. Moreover the law
linking the trapping time exponent within jets to the transport
exponent is confirmed and an accumulation towards zero of the spectrum of
finite time Lyapunov exponent is observed. The localization of a jet is
performed, and its structure is analyzed. It is clearly shown that despite a
regular coarse grained picture of the jet, motion within the jet appears as
chaotic but chaos is bounded on successive small scales.Comment: revised versio
Stabilizing the intensity of a wave amplified by a beam of particles
The intensity of an electromagnetic wave interacting self-consistently with a
beam of charged particles as in a free electron laser, displays large
oscillations due to an aggregate of particles, called the macro-particle. In
this article, we propose a strategy to stabilize the intensity by re-shaping
the macro-particle. This strategy involves the study of the linear stability
(using the residue method) of selected periodic orbits of a mean-field model.
As parameters of an additional perturbation are varied, bifurcations occur in
the system which have drastic effect on the modification of the self-consistent
dynamics, and in particular, of the macro-particle. We show how to obtain an
appropriate tuning of the parameters which is able to strongly decrease the
oscillations of the intensity without reducing its mean-value
Strip Annealing Furnaces for New Galvanizing Lines
Constant improvements to continuous annealing process technology are necessary for the production of bothnew and traditional steel grades to provide good formability and ductility and also gives higher mechanicalproperties when combined with correctly tuned steel chemical compositions.One vertical and one horizontal type furnace are to be started up at Acciaieria Arvedi S.p.A. (Italy) in 2011,these furnaces form part of the Continuous Galvanizing Line (CGL) in the Danieli Cold Mill Complex, thiscomplex also includes a six-high Tandem Coil Mill and Push-Pull Pickling Line.The furnaces will be able to match any market requirements for different annealing cycles, thus combininghigh performance with low investment and transformation costs. Short heat-up, long soaking, both slow andrapid cooling have all been included in equipment design to give any type of annealing curve and include alarge group of steel grades commonly required by the market. Planned expansion will allow for additionalslow cooling and extended over-aging time. High performance direct flame burners and radiant tubes fed bynatural gas are the key to guarantee strip quality and low maintenance costs. Flexible rapid jet coolingperforms different cooling rates to accommodate the metallurgy of several different steel grades
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