Clinical presentation and treatment of multifocal epitrichial sweat gland carcinoma in a horse

Epitrichial gland carcinoma is a very rare type of skin tumour in horses. This report describes a horse presenting multiple nodules with associated normal, alopecic and ulcerated skin diagnosed via histopathology as epitrichial gland carcinoma. Treatment consisted of combined surgical excision, topical therapy for ulcerated nodules and cryotherapy for non-ulcerated tumours. Six months following therapy, the excised masses had not regrown and only 10 out of 25 small tumours previously treated with cryotherapy were noticeable

Smooth-filamental transition of active tracer fields stirred by chaotic advection

The stationary-state spatial structure of interacting chemical fields is investigated in the nondiffusive limit. The evolution of fluid parcels is described by independent dynamical systems driven by chaotic advection. The distribution can be filamental or smooth depending on the relative strength of the dispersion due to chaotic advection and the stability of the chemical dynamics. We give the condition for the smooth-filamental transition and relate the Hölder exponent of the filamental structure to the Lyapunov exponents. Theoretical findings are illustrated by numerical experiments. © 1999 The American Physical Society.Funded by a Royal Society-NATO Postdoctoral Fellowship and C. L. was funded by CICYT projects (No. MAR95-1861 and No. MAR98-0840).Peer Reviewe

Characterization of coherent structures in three-dimensional turbulent flows using the finite-size Lyapunov exponent

arXiv:1207.1975In this paper, we use the finite-size Lyapunov exponent (FSLE) to characterize Lagrangian coherent structures in three-dimensional (3D) turbulent flows. Lagrangian coherent structures act as the organizers of transport in fluid flows and are crucial to understand their stirring and mixing properties. Generalized maxima (ridges) of the FSLE fields are used to locate these coherent structures. 3D FSLE fields are calculated in two phenomenologically distinct turbulent flows: a wall-bounded flow (channel flow) and a regional oceanic flow obtained by the numerical solution of the primitive equations where two-dimensional (2D) turbulence dominates. In the channel flow, autocorrelations of the FSLE field show that the structure is substantially different from the near wall to the mid-channel region and relates well to the more widely studied Eulerian coherent structure of the turbulent channel flow. The ridges of the FSLE field have complex shapes due to the 3D character of the turbulent fluctuations. In the oceanic flow, strong horizontal stirring is present and the flow regime is similar to that of 2D turbulence where the domain is populated by coherent eddies that interact strongly. This in turn results in the presence of high FSLE lines throughout the domain leading to strong non-local mixing. The ridges of the FSLE field are quasi-vertical surfaces, indicating that the horizontal dynamics dominates the flow. Indeed, due to rotation and stratification, vertical motions in the ocean are much less intense than horizontal ones. This suppression is absent in the channel flow, as the 3D character of the FSLE ridges shows. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to 'Lyapunov analysis: from dynamical systems theory to applications'. © 2013 IOP Publishing Ltd.This work was supported by Ministerio de Economía y Competitividad (Spain) and Fondo Europeo de Desarrollo Regional through project FISICOS (FIS2007-60327). JHB acknowledges financial support of the Portuguese FCT (Foundation for Science and Technology) and Fundo Social Europeo (FSE/QREN/POPH) through the predoctoral grant SFRH/BD/63840/2009.N

Lagrangian Coherent Structures in three-dimensional flows

arXiv:1207.1975v1Lagrangian Coherent Structures (LCS) act as the organizers of transport in fluid flows and are crucial to understand their stirring and mixing properties. In the case of oceanic flows, LCS are known to drive biological dynamics, from plankton to top predators, which stresses the importance of their characterization in realistic flows. Lyapunov exponents are useful tools to compute LCSs. In this paper we have used the Finite-Size Lyapunov Exponent (FSLE) to identify LCSs in two different types of three-dimensional turbulent velocity fields. First, in a canonical turbulent flow (channel flow between two parallel plates) the LCSs have a complex three-dimensional shape and are advected by the flow. Second, in an oceanographic setting (a regional simulation of the Benguela area) the LCSs also show a complex pattern on the horizontal but the small vertical velocities typical of oceanic flows result in a curtain-like shape.Supported by Ministerio de Econom a y Competitividad (Spain) and Fondo Europeo de Desarrollo Regional through projects FISICOS (FIS2007-60327). JHB acknowledges nancial support of the Portuguese FCT (Foundation for Science and Technology) and Fundo Social Europeu (FSE/QREN/POPH) through the predoctoral grant SFRH/BD/63840/2009.Peer reviewe

Pulsed interaction signals as a route to biological pattern formation

We identify a mechanism for biological spatial pattern formation arising from the pulsed character of the signals that mediate interactions between individuals in a population. Our general population-signal framework shows that while for a slow signal-dynamics limit no pattern formation is observed for any values of the model parameters, for a fast limit, on the contrary, pattern formation can occur. Furthermore, at these limits, our framework reduces, respectively, to reaction-diffusion and spatially nonlocal models bridging the approaches and clarifying their scope

Multiple time-scale approach for a system of Brownian particles in a non-uniform temperature field

The Smoluchowsky equation for a system of interacting Brownian particles in a temperature gradient is derived from the Kramers equation by means of a multiple time-scale method. The interparticle interactions are assumed to be represented by a mean-field description. We present numerical results that compare well with the theoretical prediction together with an extensive discussion on the prescription of the Langevin equation in overdamped systems.Comment: 8 pages, 2 figure

The GALANTE Photometric System

This paper describes the characterization of the GALANTE photometric system, a seven intermediate- and narrow-band filter system with a wavelength coverage from 3000 $\r{A}$ to 9000 $\r{A}$ . We describe the photometric system presenting the full sensitivity curve as a product of the filter sensitivity, CCD, telescope mirror, and atmospheric transmission curves, as well as some first- and second-order moments of this sensitivity function. The GALANTE photometric system is composed of four filters from the J-PLUS photometric system, a twelve broad-to-narrow filter system, and three exclusive filters, specifically designed to measure the physical parameters of stars such as effective temperature $T_{\rm eff}$, $\log(g)$, metallicity, colour excess $E(4405-5495)$, and extinction type $R_{5495}$. Two libraries, the Next Generation Spectral Library (NGSL) and the one presented in Ma\'iz Apell\'aniz & Weiler (2018), have been used to determine the transformation equations between the Sloan Digital Sky Survey ($\textit{SDSS}$) $\textit{ugriz}$ photometry and the GALANTE photometric system. We will use this transformation to calibrate the zero points of GALANTE images. To this end, a preliminary photometric calibration of GALANTE has been made based on two different $\textit{griz}$ libraries ($\textit{SDSS}$ DR12 and ATLAS All-Sky Stellar Reference Catalog, hereinafter $\textit{RefCat2}$). A comparison between both zero points is performed leading us to the choice of $\textit{RefCat2}$ as the base catalogue for this calibration, and applied to a field in the Cyg OB2 association.Comment: Accepted in MNRA

Landscape-induced spatial oscillations in population dynamics

We study the effect that disturbances in the ecological landscape exert on the spatial distribution of a population that evolves according to the nonlocal FKPP equation. Using both numerical and analytical techniques, we explore the three types of stationary profiles that can develop near abrupt spatial variations in the environmental conditions vital for population growth: sustained oscillations, decaying oscillations and exponential relaxation towards a flat profile. We relate the wavelength and decay length of the wrinkles to the shape of the interaction kernel. Since these spatial structures encode details about the interaction among individuals, we discuss how heterogeneities reveal information that would be hidden in a flat landscape