Solitons and Vertex Operators in Twisted Affine Toda Field Theories

Affine Toda field theories in two dimensions constitute families of integrable, relativistically invariant field theories in correspondence with the affine Kac-Moody algebras. The particles which are the quantum excitations of the fields display interesting patterns in their masses and coupling and which have recently been shown to extend to the classical soliton solutions arising when the couplings are imaginary. Here these results are extended from the untwisted to the twisted algebras. The new soliton solutions and their masses are found by a folding procedure which can be applied to the affine Kac-Moody algebras themselves to provide new insights into their structures. The relevant foldings are related to inner automorphisms of the associated finite dimensional Lie group which are calculated explicitly and related to what is known as the twisted Coxeter element. The fact that the twisted affine Kac-Moody algebras possess vertex operator constructions emerges naturally and is relevant to the soliton solutions.Comment: 27 pages (harvmac) + 3 figures (LaTex) at the end of the file, Swansea SWAT/93-94/1

Automatic Counting of Aedes aegypti Eggs in Images of Ovitraps

Non

(Super)Gelators derived from push-pull chromophores: Synthesis, gelling properties and second harmonic generation

The present work takes advantage of the self-assembly process occuring along organogelation, to organize Second Harmonic Generation (SHG) active chromophores. To do so, three push-pull chromophores endowed with a dodecyl urea chain were synthesized and characterized. Their organogelating properties were studied in a wide range of solvents. Despite similar architectures, these derivatives exhibit very different gelling properties, from supergelation to absence of gelling ability. The utilization of the Hansen solubility parameters allows for observing clear relationships between the gelled solvents and critical gelation concentrations. By evaporating the solvents from the organogels, xerogel materials were prepared and systematically studied by means of optical and electron microscopies as well as SHG microscopy. These studies demonstrate the critical role of the solvent over materials structuring and allow generalizing the approach exploiting organogelation as a structuring tool to spontaneously organize push-pull chromophores into SHG-active materials

Theoretical framework of radiation force in surface acoustic waves for modulated particle sorting

Sorting specific target entities from sample mixtures is commonly used in many macroscale laboratory processing, such as disease diagnosis or treatment. Downscaling of sorting systems enables less laboratory space and fewer quantities of sample and reagent. Such lab-on-a-chip devices can perform separation functions using passive or active sorting methods. Such a method, acoustic sorting, when used in microfluidics, offers contactless, label-free, non-invasive manipulation of target cells or particles and is therefore the topic of active current research. Our phase-modulated sorting technique complements traditional time-of-flight techniques and offers higher sensitivity separation using a periodic signal. By cycling of this periodic signal, the target entities are gradually displaced compared to the background debris, thereby achieving sorting. In this paper, we extend the knowledge on phase-modulated sorting techniques. Firstly, using numerical simulations, we confirm the sorting role of our proposed primary acoustic radiation force within surface wave devices. Secondly, a threefold agreement between analytical, numerical and experimental sorting trajectories is presented

Generating airborne ultrasonic amplitude patterns using an open hardware phased array

Holographic methods from optics can be adapted to acoustics for enabling novel applications in particle manipulation or patterning by generating dynamic custom-tailored acoustic fields. Here, we present three contributions towards making the field of acoustic holography more widespread. Firstly, we introduce an iterative algorithm that accurately calculates the amplitudes and phases of an array of ultrasound emitters in order to create a target amplitude field in mid-air. Secondly, we use the algorithm to analyse the impact of spatial, amplitude and phase emission resolution on the resulting acoustic field, thus providing engineering insights towards array design. For example, we show an onset of diminishing returns for smaller than a quarter-wavelength sized emitters and a phase and amplitude resolution of eight and four divisions per period, respectively. Lastly, we present a hardware platform for the generation of acoustic holograms. The array is integrated in a single board composed of 256 emitters operating at 40 kHz. We hope that the results and procedures described within this paper enable researchers to build their own ultrasonic arrays and explore novel applications of ultrasonic holograms.This research was funded by the Government of Navarre (FEDER) 0011-1365-2019-000086 and from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101017746, TOUCHLESS

Monte-Carlo based sensitivity analysis of acoustic sorting methods

Separation in microfluidic devices is a crucial enabling step for many industrial, biomedical, clinical or chemical applications. Acoustic methods offer contactless, biocompatible, scalable sorting with high degree of reconfigurability and are therefore favored techniques. The literature reports on various techniques to achieve particle separation, but these do not investigate the sensitivity of these methods or are difficult to compare due to the lack of figures of merit. In this paper, we present analytical and numerical sensitivity analysis of the time-of-flight and a phase-modulated sorting scheme against various extrinsic and intrinsic properties. The results reveal great robustness of the phase-modulated sorting method against variations of the flow rate or acoustic energy density, while the time-of-flight method shows lower efficiency drop against size and density variations. The results presented in this paper provide a better understanding of the two sorting methods and offer advice on the selection of the right technique for a given sorting application

Exact conserved quantities on the cylinder II: off-critical case

With the aim of exploring a massive model corresponding to the perturbation of the conformal model [hep-th/0211094] the nonlinear integral equation for a quantum system consisting of left and right KdV equations coupled on the cylinder is derived from an integrable lattice field theory. The eigenvalues of the energy and of the transfer matrix (and of all the other local integrals of motion) are expressed in terms of the corresponding solutions of the nonlinear integral equation. The analytic and asymptotic behaviours of the transfer matrix are studied and given.Comment: enlarged version before sending to jurnal, second part of hep-th/021109

N=2 SYM RG Scale as Modulus for WDVV Equations

We derive a new set of WDVV equations for N=2 SYM in which the renormalization scale $\Lambda$ is identified with the distinguished modulus which naturally arises in topological field theories.Comment: 6 pages, LaTe