Non-equilibrium thermodynamics of the spin Seebeck and spin Peltier effects

We study the problem of magnetization and heat currents and their associated thermodynamic forces in a magnetic system by focusing on the magnetization transport in ferromagnetic insulators like YIG. The resulting theory is applied to the longitudinal spin Seebeck and the spin Peltier effects. By focusing on the specific geometry with one YIG layer and one Pt layer, we obtain the optimal conditions for generating large magnetization currents into Pt or large temperature effects in YIG. The theoretical predictions are compared with experiments from the literature permitting to derive the values of the thermomagnetic coefficients of YIG: the magnetization diffusion length $l_M \sim 0.4 \, \mu$m and the absolute thermomagnetic power coefficient $\epsilon_M \sim 10^{-2}$ TK$^{-1}$.Comment: accepted for publication on Physical Review

Non-equilibrium thermodynamics of the longitudinal spin Seebeck effect

In this paper we employ non equilibrium thermodynamics of fluxes and forces to describe magnetization and heat transport. By the theory we are able to identify the thermodynamic driving force of the magnetization current as the gradient of the effective field $\nabla H^*$. This definition permits to define the spin Seebeck coefficient $\epsilon_M$ which relates $\nabla H^*$ and the temperature gradient $\nabla T$. By applying the theory to the geometry of the longitudinal spin Seebeck effect we are able to obtain the optimal conditions for generating large magnetization currents. Furthermore, by using the results of recent experiments, we obtain an order of magnitude for the value of $\epsilon_{M} \sim 10^{-2}$ TK$^{-1}$ for yttrium iron garnet (Y$_3$Fe$_5$O$_{12}$).Comment: accepted for publication on Physics Procedi

Dual-plane coupled phase retrieval for non-prior holographic imaging

AbstractAccurate depiction of waves in temporal and spatial is essential to the investigation of interactions between physical objects and waves. Digital holography (DH) can perform quantitative analysis of wave–matter interactions. Full detector-bandwidth reconstruction can be realized based on in-line DH. But the overlapping of twin images strongly prevents quantitative analysis. For off-axis DH, the object wave and the detector bandwidth need to satisfy certain conditions to perform reconstruction accurately. Here, we present a reliable approach involving a coupled configuration for combining two in-line holograms and one off-axis hologram, using a rapidly converging iterative procedure based on two-plane coupled phase retrieval (TwPCPR) method. It realizes a fast-convergence holographic calculation method. High-resolution and full-field reconstruction by exploiting the full bandwidth are demonstrated for complex-amplitude reconstruction. Off-axis optimization phase provides an effective initial guess to avoid stagnation and minimize the required measurements of multi-plane phase retrieval. The proposed strategy works well for more extended samples without any prior assumptions of the objects including support, non-negative, sparse constraints, etc. It helps to enhance and empower applications in wavefront sensing, computational microscopy and biological tissue analysis

Combined surgery for lipomatous hypertrophy of the interatrial septum and pulmonary carcinoma

AbstractJ Thorac Cardiovasc Surg 2002;123:564-

Metabolic syndrome and nephrolithiasis: can we hypotize a common background?

Metabolic syndrome and nephrolithiasis are quite common disorders presenting similar epidemiological characteristics. Belonging to genetic, environmental and hormonal interaction, they have high incidence and prevalence in the adult population of industrialised countries and are characterised by a high level of morbidity and mortality if not adequately identified and treated. Despite metabolic syndrome is considered a fundamental risk factor for chronic kidney diseases, is not actually known whether it is associated with nephrolithiasis beyond the effect of its individual components, in particular obesity, glucose intolerance, and hypertension. In this paper, the possible pathogenetic links between metabolic syndrome and nephrolithiasis will be presented and discussed

Non-equilibrium Thermodynamics of the Longitudinal Spin Seebeck Effect

In this paper we employ non equilibrium thermodynamics of fluxes and forces to describe magnetization and heat transport. By the theory we are able to identify the thermodynamic driving force of the magnetization current as the gradient of the effective field ▿H∗. This definition permits to define the spin Seebeck coefficient ϵM which relates ▿H∗ and the temperature gradient ▿T. By applying the theory to the geometry of the longitudinal spin Seebeck effect we are able to obtain the optimal conditions for generating large magnetization currents. Furthermore, by using the results of recent experiments, we obtain an order of magnitude for the value of ϵM ∼ 10-2 TK-1 for yttrium iron garnet (Y3Fe5O12)

L’ICF-CY in Educazione Fisica: uno strumento per la valutazione delle competenze sociali e civiche

National and international literature and legislation recognize the lead in grole of Physical Education in learning social and civic competences. Such learning can be hindered or facilitated by environmental contextual factors. In the perspective of an inclusive school, it is essential to take this factors into consideration in the assessment procedures in order to design didactic and educational interventions aimed at removing barriers and implementing environmental facilitators. The ICF-CY model issuitable for this purpose, however it is rarely used in schoolevaluation practices.The present study highlights the possibility of using the ICF-CY in Physical Education in order to orientate the formative evaluation of social and civic competences through the detection of descriptive information of social behaviors and contextual environmental factors that impact them during motor activities and recreational-sports.The research group identified significant correspondences between some ICF-CY categories and social and civic competences. On the basis of such correspondences, the group developed an operational tool for the evaluation of social and civic competences based on the ICFCY which can be directly used in the daily work of the Physical Education teacher in the first degree of the secondary school.La letteratura e la normativa, nazionale ed internazionale, riconoscono il ruolo di primo piano dell’Educazione Fisica nell’apprendimento delle competenze sociali e civiche. Tale apprendimento può essere ostacolato o facilitato dai fattori contestuali ambientali. Nella prospettiva di una scuola inclusiva, risulta fondamentale considerare questi fattori nelle procedure di valutazioneal fine di progettare interventi didattici ed educativi volti alla rimozione delle barriere e all’implementazione dei facilitatori ambientali. Il modello dell’ICF-CY risulta adeguato a tale scopo, ma è scarsamente utilizzato nelle prassi valutative a scuola.Il presente studio evidenzia la possibilità dell’impiego dell’ICF-CY in Educazione Fisica allo scopo di orientare la valutazione formativa delle competenze sociali e civiche attraverso la rilevazione di informazioni descrittive di comportamenti sociali e dei fattori contestuali ambientali che impattano sugli stessi durante le attività motorie e ludico-sportive.Il gruppo di ricerca ha individuato significative corrispondenze tra alcune categorie dell’ICFCY e le competenze sociali e civiche. Sulla base di queste corrispondenze è stato costruito uno strumento operativo di valutazione delle competenze sociali e civiche su base ICF-CY direttamente utilizzabile nel lavoro quotidiano dell’insegnante di Educazione Fisica nella scuola secondaria di primo grado

Encoding multiple holograms for speckle-noise reduction in optical display.

In digital holography (DH) a mixture of speckle and incoherent additive noise, which appears in numerical as well as in optical reconstruction, typically degrades the information of the object wavefront. Several methods have been proposed in order to suppress the noise contributions during recording or even during the reconstruction steps. Many of them are based on the incoherent combination of multiple holographic reconstructions achieving remarkable improvement, but only in the numerical reconstruction i.e. visualization on a pc monitor. So far, it has not been shown the direct synthesis of a digital hologram which provides the denoised optical reconstruction. Here, we propose a new effective method for encoding in a single complex wavefront the contribution of multiple incoherent reconstructions, thus allowing to obtain a single synthetic digital hologram that show significant speckle-reduction when optically projected by a Spatial Light Modulator (SLM)