503 research outputs found
Anomalous Drude Model
A generalization of the Drude model is studied. On the one hand, the free
motion of the particles is allowed to be sub- or superdiffusive; on the other
hand, the distribution of the time delay between collisions is allowed to have
a long tail and even a non-vanishing first moment. The collision averaged
motion is either regular diffusive or L\'evy-flight like. The anomalous
diffusion coefficients show complex scaling laws. The conductivity can be
calculated in the diffusive regime. The model is of interest for the
phenomenological study of electronic transport in quasicrystals.Comment: 4 pages, latex, 2 figures, to be published in Physical Review Letter
Smoluchowski's equation for cluster exogenous growth
We introduce an extended Smoluchowski equation describing coagulation
processes for which clusters of mass s grow between collisions with
. A physical example, dropwise condensation is provided, and
its collision kernel K is derived. In the general case, the gelation criterion
is determined. Exact solutions are found and scaling solutions are
investigated. Finally we show how these results apply to nucleation of discs on
a planeComment: Revtex, 4 pages (multicol.sty), 1 eps figures (uses epsfig
Generalized quasiperiodic Rauzy tilings
We present a geometrical description of new canonical -dimensional
codimension one quasiperiodic tilings based on generalized Fibonacci sequences.
These tilings are made up of rhombi in 2d and rhombohedra in 3d as the usual
Penrose and icosahedral tilings. Thanks to a natural indexing of the sites
according to their local environment, we easily write down, for any
approximant, the sites coordinates, the connectivity matrix and we compute the
structure factor.Comment: 11 pages, 3 EPS figures, final version with minor change
Effect of conduction electron interactions on Anderson impurities
The effect of conduction electron interactions for an Anderson impurity is
investigated in one dimension using a scaling approach. The flow diagrams are
obtained by solving the renormalization group equations numerically. It is
found that the Anderson impurity case is different from its counterpart -- the
Kondo impurity case even in the local moment region. The Kondo temperature for
an Anderson impurity shows nonmonotonous behavior, increasing for weak
interactions but decreasing for strong interactions. The implication of the
study to other related impurity models is also discussed.Comment: 10 pages, revtex, 4 figures (the postscript file is included), to
appear in Phys. Rev. B (Rapid Commun.
Effects of hyaluronic acid injections on pain and functioning in patients affected by tendinopathies: a narrative review
BACKGROUND: Tendinopathies are overuse tendon injuries showing load-dependant pain, stiffness, weakness of movement in the affected area, and impairment in the movements. The scientific interest on the role of Hyaluronic Acid (HA) for the management of tendinopathies has been increased due to its anti-inflammatory and lubricative properties. OBJECTIVE: To collect evidence regarding the effectiveness and safety of HA injections in reducing pain in patients affected by tendinopathies. METHODS: A scientific literature search was conducted using the PubMed, Medline and PEDro electronic databases. The databases were searched since their inception until July 2021. The search was limited to English language articles. Different combinations of the terms and MeSH terms 'tendinopathy', 'tendinosis', 'tendinitis', 'hyaluronic acid', 'hyaluronate', 'infiltration', 'hyaluronic injections', 'viscosupplementation' connected with various boolean operators were used for other electronic databases. RESULTS: One hundred and one records were identified from the selected databases plus three additional papers identified by the authors through other sources. After removing duplicated papers and title/abstract screening, 19 studies were included in our review (eight papers on shoulder, three on elbow, four on hand, one on knee, and three on ankle). CONCLUSION: The results showed that none of the studies report severe adverse effects and most of them support the use of HA injections in tendinopathies, with a special attention to pain reduction and functional assessment. Further studies are warranted to better investigate effects and methods of administration of HA in tendinopathies
Self-gravitating Brownian particles in two dimensions: the case of N=2 particles
We study the motion of N=2 overdamped Brownian particles in gravitational
interaction in a space of dimension d=2. This is equivalent to the simplified
motion of two biological entities interacting via chemotaxis when time delay
and degradation of the chemical are ignored. This problem also bears some
similarities with the stochastic motion of two point vortices in viscous
hydrodynamics [Agullo & Verga, Phys. Rev. E, 63, 056304 (2001)]. We
analytically obtain the density probability of finding the particles at a
distance r from each other at time t. We also determine the probability that
the particles have coalesced and formed a Dirac peak at time t (i.e. the
probability that the reduced particle has reached r=0 at time t). Finally, we
investigate the variance of the distribution and discuss the proper form
of the virial theorem for this system. The reduced particle has a normal
diffusion behaviour for small times with a gravity-modified diffusion
coefficient =r_0^2+(4k_B/\xi\mu)(T-T_*)t, where k_BT_{*}=Gm_1m_2/2 is a
critical temperature, and an anomalous diffusion for large times
~t^(1-T_*/T). As a by-product, our solution also describes the growth of
the Dirac peak (condensate) that forms in the post-collapse regime of the
Smoluchowski-Poisson system (or Keller-Segel model) for T<T_c=GMm/(4k_B). We
find that the saturation of the mass of the condensate to the total mass is
algebraic in an infinite domain and exponential in a bounded domain.Comment: Revised version (20/5/2010) accepted for publication in EPJ
Environmental Impacts of Tartaric Stabilisation Processes for Wines using Electrodialysis and Cold Treatment
The environmental impacts of the two tartaric stabilisation methods used for wines, electrodialysis andcold treatment, were studied by determining water consumption (for the process and cleaning), wasteproduced (organic load and the composition of wastewater and residues) and energy consumption, atthe pilot stage and in wineries. Thanks to an online treatment of electrodialysis brines by reverse osmosis(industrial facility that treats 30 hL wine/h), the recycling of permeates led to a 65% reduction in waterconsumption, the volume of which represented only 3.9% of the wine treated. When washing and cleaningwater from the ED-RO system was taken into account, overall water consumption was 5.5 L/hL wine. Thepresence of ethanol, due to an osmotic phenomenon with no loss of wine volume, and tartaric acid in thebrines contributes to the organic load of the brine, with a COD of close to 8.4 g O2/L. Overall electricalenergy consumption for stabilisation by electrodialysis (0.21 kWh/hL) turned out to be eight times lowerthan that of cold stabilisation. An evaluation of cold stabilisation effluents revealed that 66.6% of the CODdischarged came from the diatomaceous earth (DE), 21.8% from the washing of the filter and 11.4% fromthe washing of the cold treatment tank. The production of used DE was 2.64 g (wet weight)/L of wine, andthe ethanol present in the DE waste represented a loss in wine volume of 0.14 L/hL
Finite mass self-similar blowing-up solutions of a chemotaxis system with non-linear diffusion
For a specific choice of the diffusion, the parabolic-elliptic
Patlak-Keller-Segel system with non-linear diffusion (also referred to as the
quasi-linear Smoluchowski-Poisson equation) exhibits an interesting threshold
phenomenon: there is a critical mass such that all the solutions with
initial data of mass smaller or equal to exist globally while the
solution blows up in finite time for a large class of initial data with mass
greater than . Unlike in space dimension 2, finite mass self-similar
blowing-up solutions are shown to exist in space dimension
Oxygenâozone therapy in the rehabilitation field: state of the art on mechanisms of action, safety and effectiveness in patients with musculoskeletal disorders
In recent years, the interest in oxygenâozone (O2O3) therapy application has considerably increased in the field of rehabilitation. Despite its widespread use in common clinical practice, the biochemical effects of O2O3 are still far from being understood, although its chemical properties seem to play a pivotal role in exerting its positive effects on different pathological conditions. Indeed, the effectiveness of O2O3 therapy might be partly due to the moderate oxidative stress produced by O3 interactions with biological components. O2O3 therapy is widely used as an adjuvant therapeutic option in several pathological conditions characterized by chronic inflammatory processes and immune overâactivation, and most musculoskeletal disorders share these pathophysiological processes. The present comprehensive review depicts the stateâofâtheâart on the mechanisms of action, safety and effectiveness of O2O3 therapy in the complex scenario of the management of musculoskeletal disorders. Taken together, our findings suggest that O2O3 therapy seems to reduce pain and improve functioning in patients affected by low back pain and knee osteoarthritis, as reported by several studies in the literature. However, to date, further studies are warranted to clearly investigate the therapeutic effects of this promising therapy on other musculoskeletal disorders in the field of rehabilitation
Coarsening in the q-State Potts Model and the Ising Model with Globally Conserved Magnetization
We study the nonequilibrium dynamics of the -state Potts model following a
quench from the high temperature disordered phase to zero temperature. The time
dependent two-point correlation functions of the order parameter field satisfy
dynamic scaling with a length scale . In particular, the
autocorrelation function decays as . We illustrate these
properties by solving exactly the kinetic Potts model in . We then analyze
a Langevin equation of an appropriate field theory to compute these correlation
functions for general and . We establish a correspondence between the
two-point correlations of the -state Potts model and those of a kinetic
Ising model evolving with a fixed magnetization . The dynamics of this
Ising model is solved exactly in the large q limit, and in the limit of a large
number of components for the order parameter. For general and in any
dimension, we introduce a Gaussian closure approximation and calculate within
this approximation the scaling functions and the exponent . These
are in good agreement with the direct numerical simulations of the Potts model
as well as the kinetic Ising model with fixed magnetization. We also discuss
the existing and possible experimental realizations of these models.Comment: TeX, Vanilla.sty is needed. [Admin note: author contacted regarding
missing figure1 but is unable to supply, see journal version (Nov99)
- âŠ