1,217 research outputs found
Boltzmann-Gibbs thermal equilibrium distribution for classical systems and Newton law: A computational discussion
We implement a general numerical calculation that allows for a direct
comparison between nonlinear Hamiltonian dynamics and the Boltzmann-Gibbs
canonical distribution in Gibbs -space. Using paradigmatic
first-neighbor models, namely, the inertial XY ferromagnet and the
Fermi-Pasta-Ulam -model, we show that at intermediate energies the
Boltzmann-Gibbs equilibrium distribution is a consequence of Newton second law
(). At higher energies we discuss partial agreement
between time and ensemble averages.Comment: New title, revision of the text. EPJ latex, 4 figure
On Weierstra{\ss} semigroups at one and two points and their corresponding Poincar\'e series
The aim of this paper is to introduce and investigate the Poincar\'e series
associated with the Weierstra{\ss} semigroup of one and two rational points at
a (not necessarily irreducible) non-singular projective algebraic curve defined
over a finite field, as well as to describe their functional equations in the
case of an affine complete intersection.Comment: Beginning of Section 3 and Subsection 3.1 were modifie
Asteroseismology of evolved stars to constrain the internal transport of angular momentum. VI. Testing a parametric formulation for the azimuthal magneto-rotational instability
Asteroseismic measurements of the internal rotation rate in evolved stars
pointed out to a lack of angular momentum (AM) transport in stellar evolution
models. Several physical processes in addition to hydrodynamical ones were
proposed as candidates for the missing mechanism. Nonetheless, no current
candidate can satisfy all the constraints provided by asteroseismology. We
revisit the role of a candidate process whose efficiency scales with the
contrast between the rotation rate of the core and the surface which was
proposed to be related to the azimuthal magneto-rotational instability (AMRI)
by Spada et al. We compute stellar evolution models of low- and
intermediate-mass stars with the parametric formulation of AM transport
proposed by Spada et al. until the end of the core-helium burning for low- and
intermediate-mass stars and compare our results to the latest asteroseismic
constraints available in the post main sequence phase. Both hydrogen-shell
burning stars in the red giant branch and core-helium burning stars of low- and
intermediate-mass in the mass range can be simultaneously reproduced by this kind of parametrisation.
Given current constraints from asteroseismology, the core rotation rate of
post-main sequence stars seems to be well explained by a process whose
efficiency is regulated by the internal degree of differential rotation in
radiative zones.Comment: Accepted for publication in Astronomy & Astrophysics. 10 pages, 10
figures, 1 appendi
Non-extensive entropy from incomplete knowledge of Shannon entropy?
In this paper we give an interpretation of Tsallis' nonextensive statistical
mechanics based upon the information-theoretic point of view of Luzzi et al.
[cond-mat/0306217; cond-mat/0306247; cond-mat/0307325], suggesting Tsallis'
entropy to be not a fundamental concept but rather a derived one, stemming from
an incomplete knowledge of the system, not taking properly into account its
interaction with the environment. This interpretation seems to avoid some
problems occurring with the original interpretation of Tsallis statistics.Comment: v.4. 11 pages. Title changed. Content substantially changed: added
discussion of several points raised by various referees and readers; Also
reference made to work by Luzzi, Vasconcellos, Galvao Ramos. Physica Scripta,
to appea
Array-Based Detection of Persistent Organic Pollutants via Cyclodextrin Promoted Energy Transfer
We report herein the selective array-based detection of 30 persistent organic pollutants via cyclodextrin-promoted energy transfer. The use of three fluorophores enabled the development of an array that classified 30 analytes with 100% accuracy and identified unknown analytes with 96% accuracy, as well as identifying 92% of analytes in urine
On "Ergodicity and Central Limit Theorem in Systems with Long-Range Interactions" by Figueiredo et al
In the present paper we refute the criticism advanced in a recent preprint by
Figueiredo et al [1] about the possible application of the -generalized
Central Limit Theorem (CLT) to a paradigmatic long-range-interacting many-body
classical Hamiltonian system, the so-called Hamiltonian Mean Field (HMF) model.
We exhibit that, contrary to what is claimed by these authors and in accordance
with our previous results, -Gaussian-like curves are possible and real
attractors for a certain class of initial conditions, namely the one which
produces nontrivial longstanding quasi-stationary states before the arrival,
only for finite size, to the thermal equilibrium.Comment: 2 pages, 2 figures. Short version of the paper, accepted for
publication in Europhysics Letters, (2009) in pres
Design of a 5G Multimedia Broadcast Application Function Supporting Adaptive Error Recovery
The demand for mobile multimedia streaming services has been steadily growing
in recent years. Mobile multimedia broadcasting addresses the shortage of radio
resources but introduces a network error recovery problem. Retransmitting
multimedia segments that are not correctly broadcast can cause service
disruptions and increased service latency, affecting the quality of experience
perceived by end users. With the advent of networking paradigms based on
virtualization technologies, mobile networks have been enabled with more
flexibility and agility to deploy innovative services that improve the
utilization of available network resources. This paper discusses how mobile
multimedia broadcast services can be designed to prevent service degradation by
using the computing capabilities provided by multiaccess edge computing (MEC)
platforms in the context of a 5G network architecture. An experimental platform
has been developed to evaluate the feasibility of a MEC application to provide
adaptive error recovery for multimedia broadcast services. The results of the
experiments carried out show that the proposal provides a flexible mechanism
that can be deployed at the network edge to lower the impact of transmission
errors on latency and service disruptions.Comment: 14 pages, 10 figure
Gas chromatography–tandem mass spectrometry with atmospheric pressure chemical ionization for fluorotelomer alcohols and perfluorinated sulfonamides determination
Ionization and in source-fragmentation behavior of four fluorotelomer alcohols (FTOH) (4:2 FTOH, 6:2 FTOH, 8:2 FTOH and 10:2 FTOH) and four N-alkyl fluorooctane sulfonamides/-ethanols (N-MeFOSA, N-EtFOSA, N-MeFOSE and N-EtFOSE) by APCI has been studied and compared with the traditionally used EI and CI. Protonated molecule was the base peak of the APCI spectrum in all cases giving the possibility of selecting it as a precursor ion for MS/MS experiments. Following, CID fragmentation showed common product ions for all FOSAs/FOSEs (C4F7 and C3F5). Nevertheless, the different functionality gave characteristic pattern fragmentations. For instance, FTOHs mainly loss H2O + HF, FOSAs showed the losses of SO2 and HF while FOSEs showed the losses of H2O and SO2. Linearity, repeatability and LODs have been studied obtaining instrumental LODs between 1 and 5 fg. Finally, application to river water and influent and effluent waste water samples has been carried out in order to investigate the improvements in detection capabilities of this new source in comparison with the traditionally used EI/CI sources. Matrix effects in APCI have been evaluated in terms of signal enhancement/suppression when comparing standards in solvent and matrix. No matrix effects were observed and concentrations found in samples were in the range of 1–100 pg L−1 far below the LODs achieved with methods previously reported. Unknown related perfluoroalkyl substances, as methyl-sulfone and methyl-sulfoxide analogues for FTOHs, were also discovered and tentatively identified.The authors wish to acknowledge the financial support received from Spanish Ministry of Economy and Competitiveness under the project CTQ2012-30836 and from the Agency for Administration of University and Research Grants (Generalitat de Catalunya, Spain) under the project 2014 SGR-539. They are very grateful to the Serveis Centrals d’Instrumentació Científica (SCIC) of University Jaume I for the use of the GC XevoTQ-S
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