Modal analysis and nonlinear characterization of an airborne power ultrasonic transducer with rectangular plate radiator

Some industrial processes like particle agglomeration or food dehydration among others can be enhanced by the use of power ultrasonic technologies. These technologies are based on an airborne power ultrasonic transducer (APUT) constituted by a pre-stressed Langevin-type transducer, a mechanical amplifier and an extensive plate radiator. In order to produce the desired effects in industrial processing, the transducer has to vibrate in an extensional mode driving an extensive radiator in the desired flexural mode with high amplitude displacements. Due to the generation of these high amplitude displacements in the radiator surfaces, non-linear effects like frequency shifts, hysteresis or modal interactions, among others, may be produced in the transducer behavior. When any nonlinear effect appears, when applying power, the stability and efficiency of this ultrasonic technology decreases, and the transducer may be damaged depending on the excitation power level and the nature of the nonlinearity. In this paper, an APUT with flat rectangular radiator is presented, as the active part of an innovative system with stepped reflectors. The nonlinear behavior of the APUT has been characterized numerically and experimentally in case of the modal analysis and experimentally in the case of dynamic analysis. According to the results obtained after the experiments, no modal interactions are expected, nor do other nonlinear effects

Locality of temperature

This work is concerned with thermal quantum states of Hamiltonians on spin and fermionic lattice systems with short range interactions. We provide results leading to a local definition of temperature, thereby extending the notion of "intensivity of temperature" to interacting quantum models. More precisely, we derive a perturbation formula for thermal states. The influence of the perturbation is exactly given in terms of a generalized covariance. For this covariance, we prove exponential clustering of correlations above a universal critical temperature that upper bounds physical critical temperatures such as the Curie temperature. As a corollary, we obtain that above the critical temperature, thermal states are stable against distant Hamiltonian perturbations. Moreover, our results imply that above the critical temperature, local expectation values can be approximated efficiently in the error and the system size.Comment: 11 pages + 6 pages appendix, 6 figures; proof of the clustering theorem corrected, improved presentatio

Marginal resection and adjuvant strontium plesiotherapy in the management of feline eyelid malignant peripheral nerve sheath tumours: two cases

Case series summary Two cats with a marginally resected eyelid malignant peripheral nerve sheath tumour were treated with adjuvant strontium plesiotherapy a few weeks after surgery. The dose applied in both cases was 200 Gy to the surface, in five fractions, on a Monday–Wednesday–Friday basis. The treatment aimed to achieve a clinical margin of approximately 1 cm around the surgical scar and multiple application fields were required to cover such an area. Local recurrence was not seen in either case after 1330 and 645 days, respectively. Relevance and novel information The majority of periocular malignant peripheral nerve sheath tumours reported in the literature recur after surgery. In the two cases described in this report the combination of surgery and adjuvant plesiotherapy has been able to provide good local control with minimal toxicity. This multimodal approach could be considered as an alternative to aggressive surgery such as enucleation or exenteration

Remodelado gingival estético mediante cirugía láser

Los avances de la ciencia y la aplicación de la tecnología hizo posible el desarrollo de nuevas herramientas que mejoran o facilitan los resultados terapéuticos. Aplicando los postulados teóricos de Einstein, Maiman en 1960 creó el primer Emisor láser, utilizando como medio activo el rubí. En 1970 Pattel desarrolló el primer láser de CO2 que en 1976 fue aprobada su utilización en tejidos blandos de la cavidad bucal. En nuestros tiempos se cuenta con varios emisores láser que abarcan todo el espectro electromagnético desde ultravioleta hasta infrarrojo, y de esta manera se amplía la búsqueda del efecto deseado en cada tejido. Así como en la actualidad es aplicado en muchas ramas de la medicina.Fil: Riera, José M.. Universidad Nacional de Cuyo. Facultad de Odontología

Strong coupling corrections in quantum thermodynamics

Quantum systems strongly coupled to many-body systems equilibrate to the reduced state of a global thermal state, deviating from the local thermal state of the system as it occurs in the weak-coupling limit. Taking this insight as a starting point, we study the thermodynamics of systems strongly coupled to thermal baths. First, we provide strong-coupling corrections to the second law applicable to general systems in three of its different readings: As a statement of maximal extractable work, on heat dissipation, and bound to the Carnot efficiency. These corrections become relevant for small quantum systems and always vanish in first order in the interaction strength. We then move to the question of power of heat engines, obtaining a bound on the power enhancement due to strong coupling. Our results are exemplified on the paradigmatic situation of non-Markovian quantum Brownian motion.Comment: 20 pages, 3 figures, version two is substantially revised and contains new result

Work and entropy production in generalised Gibbs ensembles

Recent years have seen an enormously revived interest in the study of thermodynamic notions in the quantum regime. This applies both to the study of notions of work extraction in thermal machines in the quantum regime, as well as to questions of equilibration and thermalisation of interacting quantum many-body systems as such. In this work we bring together these two lines of research by studying work extraction in a closed system that undergoes a sequence of quenches and equilibration steps concomitant with free evolutions. In this way, we incorporate an important insight from the study of the dynamics of quantum many body systems: the evolution of closed systems is expected to be well described, for relevant observables and most times, by a suitable equilibrium state. We will consider three kinds of equilibration, namely to (i) the time averaged state, (ii) the Gibbs ensemble and (iii) the generalised Gibbs ensemble (GGE), reflecting further constants of motion in integrable models. For each effective description, we investigate notions of entropy production, the validity of the minimal work principle and properties of optimal work extraction protocols. While we keep the discussion general, much room is dedicated to the discussion of paradigmatic non-interacting fermionic quantum many-body systems, for which we identify significant differences with respect to the role of the minimal work principle. Our work not only has implications for experiments with cold atoms, but also can be viewed as suggesting a mindset for quantum thermodynamics where the role of the external heat baths is instead played by the system itself, with its internal degrees of freedom bringing coarse-grained observables to equilibrium.Comment: 22 pages, 4 figures, improvements in presentatio

Towards a feminist politics of desire: Caring, resisting, and becoming. Review of the book Feminism and vital politics of depression and recovery (Simone Fullagar, Wendy O'Brien & Adele Pavlidis, 2019)

Biomedical imaginaries on mental disorders are generally based on linear structures of causal connections focused on the individual agency of recovery. Those usually don't include the critical contributions by feminist researchers that have largely proposed different connections between women's social and emotional lives, mental health diagnosis and forms of gender discrimination, inequality, violence and abuse suffered by women in both public and private spheres (Appignanesi, 2011; Chandler, 2016; McDermott & Roen, 2016; Stone & Kokanovic, 2016; Stoppard, 2000; Ussher, 1991; Wiener, 2005 in Fullagar, O'Brien & Pavlidis, 2019). Feminism and vital politics of depression and recovery by Simone Fullagar, Wendy O'Brien and Adele Pavlidis (2019) is an invitation to reconfigure discourses, imaginaries and narratives on mental health from a new materialist approach, by moving beyond individual problems to collective experiences that shape a feminist ethos. The authors invite readers "to engage with this book as a co-constituted process of reading-writing through visceral connections guts, brains, hearts, skin, words, images, surfaces to explore how gender matters" (Fullagar, O'Brien & Pavlidis, 2019, p. 1)