5,069 research outputs found
Spinodal instability growth in new stochastic approaches
Are spinodal instabilities the leading mechanism in the fragmentation of a
fermionic system? Numerous experimental indications suggest such a scenario and
stimulated much effort in giving a suitable description, without being
finalised in a dedicated transport model.
On the one hand, the bulk character of spinodal behaviour requires an
accurate treatment of the one-body dynamics, in presence of mechanical
instabilities. On the other hand, pure mean-field implementations do not apply
to situations where instabilities, bifurcations and chaos are present. The
evolution of instabilities should be treated in a large-amplitude framework
requiring fluctuations of Langevin type.
We present new stochastic approaches constructed by requiring a thorough
description of the mean-field response in presence of instabilities. Their
particular relevance is an improved description of the spinodal fragmentation
mechanism at the threshold, where the instability growth is frustrated by the
mean-field resilience.Comment: Conf. proc. IWM2014-EC, Catania, 6-9 May 201
On the Stability of Fundamental Couplings in the Galaxy
Astrophysical tests of the stability of Nature's fundamental couplings are a
key probe of the standard paradigms in fundamental physics and cosmology. In
this report we discuss updated constraints on the stability of the
fine-structure constant and the proton-to-electron mass ratio
within the Galaxy. We revisit and improve upon the analysis by
Truppe {\it et al.} by allowing for the possibility of simultaneous variations
of both couplings and also by combining them with the recent measurements by
Levshakov {\it et al.} By considering representative unification scenarios we
find no evidence for variations of at the 0.4 ppm level, and of
at the 0.6 ppm level; if one uses the Levshakov bound on as a prior,
the bound is improved to 0.1 ppm. We also highlight how these
measurements can constrain (and discriminate among) several fundamental physics
paradigms.Comment: 7 pages, 1 figur
CVD of CrO2 Thin Films: Influence of the Deposition Parameters on their Structural and Magnetic Properties
This work reports on the synthesis of CrO2 thin films by atmospheric pressure
CVD using chromium trioxide (CrO3) and oxygen. Highly oriented (100) CrO2 films
containing highly oriented (0001) Cr2O3 were grown onto Al2O3(0001) substrates.
Films display a sharp magnetic transition at 375 K and a saturation
magnetization of 1.92 Bohr magnetons per f.u., close to the bulk value of 2
Bohr magnetons per f.u. for the CrO2.
Keywords: Chromium dioxide (CrO2), Atmospheric pressure CVD, Spintronics.Comment: 5 pages, 6 figure
Solving 1ODEs with functions
Here we present a new approach to deal with first order ordinary differential
equations (1ODEs), presenting functions. This method is an alternative to the
one we have presented in [1]. In [2], we have establish the theoretical
background to deal, in the extended Prelle-Singer approach context, with
systems of 1ODEs. In this present paper, we will apply these results in order
to produce a method that is more efficient in a great number of cases.
Directly, the solving of 1ODEs is applicable to any problem presenting
parameters to which the rate of change is related to the parameter itself.
Apart from that, the solving of 1ODEs can be a part of larger mathematical
processes vital to dealing with many problems.Comment: 31 page
Description and molecular phylogeny of a new and one known needle nematode of the genus Paralongidorus (Nematoda: Longidoridae) from grapevine in Portugal
A new and a known longidorid nematode, Paralongidorus lusitanicus n. sp. and Paralongidorus plesioepimikis, are described and illustrated from populations extracted from soil associated with grapevine (Vitis vinifera L.) from Escaroupim and Pó (central-Western Portugal), respectively. The new needle nematode P. lusitanicus n. sp. is characterised by a very large body size (8072–12,022 μm), an expanded and rounded lip region, ca 30 μm wide, with a clear constriction followed by a depression posterior to the amphidial aperture, amphidial fovea very large (11.0–19.0 μm), stirrup-shaped, with conspicuous slit-like aperture as shown in scanning electron microscopy studies, a very long and flexible odontostyle (180.0–223.0 μm), guiding ring located at 28.0–41.5 μm from anterior end, vulva anterior to the mid-body (34–41%), a dorsally convex-conoid tail with rounded terminus (29–42 μm long), bearing two or three pairs of caudal pores and males common (ratio 1:1.6 females) with spicules ca 80 μm long. Morphological and morphometric traits for P. plesioepimikis fit well with the original description, and is reported for the first time in Portugal. Integrative diagnosis of both species was completed with molecular data obtained using D2-D3 expansion segments of 28S rDNA, ITS1-rDNA and partial 18S–rDNA. The phylogenetic relationships of these species with other Paralongidorus spp. using these three molecular markers indicated that P. lusitanicus n. sp. clustered together with other Paralongidorus spp. forming a sister clade with P. plesioepimikis, both of them sharing a large body, long odontostyle, an anteriorly located vulva and an expanded and rounded lip region with a clear constriction followed by a depression posterior to the amphidial aperture
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