Non-contact elastography methods in mechanobiology: a point of view

In recent decades, mechanobiology has emerged as a novel perspective in the context of basic biomedical research. It is now widely recognized that living cells respond not only to chemical stimuli (for example drugs), but they are also able to decipher mechanical cues, such as the rigidity of the underlying matrix or the presence of shear forces. Probing the viscoelastic properties of cells and their local microenvironment with sub-micrometer resolution is required to study this complex interplay and dig deeper into the mechanobiology of single cells. Current approaches to measure mechanical properties of adherent cells mainly rely on the exploitation of miniaturized indenters, to poke single cells while measuring the corresponding deformation. This method provides a neat implementation of the everyday approach to measure mechanical properties of a material, but it typically results in a very low throughput and invasive experimental protocol, poorly translatable towards three-dimensional living tissues and biological constructs. To overcome the main limitations of nanoindentation experiments, a radical paradigm change is foreseen, adopting next generation contact-less methods to measure mechanical properties of biological samples with sub-cell resolution. Here we briefly introduce the field of single cell mechanical characterization, and we concentrate on a promising high resolution optical elastography technique, Brillouin spectroscopy. This non-contact technique is rapidly emerging as a potential breakthrough innovation in biomechanics, but the application to single cells is still in its infancy

Optimal Advance Angle for Aided Maximum-Speed-Node Design of Switched Reluctance Machines

In the design processes of Switched Reluctance Machines that operate in wide constant power speed ranges, the maximum power available at maximum speed must be evaluated for every machine candidate. This is critical to ensure compliance with the power requirement. Important parameters to include in the design routine include the duration of the energizing period and the advance of the turn-on instant (i.e. advance angle). The latter is highly related to the machine geometry and is usually evaluated through time-consuming finite-element based iterative methods. In this paper, a simple, yet novel analytical model is proposed to cater for the torque-maximising advance angle in a closed-form analytical expression, directly from the machine geometry. The goal is to provide a non-iterative design tool that speeds up the design process. Successful validations against finite element analyses and experimental results on an SR machine prototype are reported. The main outcome of this paper is shown by the improvement in computation time, without any significant loss of accuracy

Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria-Europe plate boundary (Western Alps, Calabria, Corsica)

Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary

Diversity and ethics in trauma and acute care surgery teams: results from an international survey

Background Investigating the context of trauma and acute care surgery, the article aims at understanding the factors that can enhance some ethical aspects, namely the importance of patient consent, the perceptiveness of the ethical role of the trauma leader, and the perceived importance of ethics as an educational subject. Methods The article employs an international questionnaire promoted by the World Society of Emergency Surgery. Results Through the analysis of 402 fully filled questionnaires by surgeons from 72 different countries, the three main ethical topics are investigated through the lens of gender, membership of an academic or non-academic institution, an official trauma team, and a diverse group. In general terms, results highlight greater attention paid by surgeons belonging to academic institutions, official trauma teams, and diverse groups. Conclusions Our results underline that some organizational factors (e.g., the fact that the team belongs to a university context or is more diverse) might lead to the development of a higher sensibility on ethical matters. Embracing cultural diversity forces trauma teams to deal with different mindsets. Organizations should, therefore, consider those elements in defining their organizational procedures. Level of evidence Trauma and acute care teams work under tremendous pressure and complex circumstances, with their members needing to make ethical decisions quickly. The international survey allowed to shed light on how team assembly decisions might represent an opportunity to coordinate team member actions and increase performance

Il ruolo attuale della esplorazione bilaterale del collo nel trattamento dell’iperparatiroidismo primario

La chirurgia è l'unico trattamento realmente curativo per l'iperparatiroidismo primario (pHPT). Per tutti i pazienti con pHPT biochimicamente documentato c?è indicazione all'intervento, poiché anche coloro apparentemente asintomatici hanno dei disturbi lievi e progressivi che beneficiano del trattamento chirurgico. Da quando Felix Mandl nel 1925 realizzò con successo la prima esplorazione bilaterale del collo (BNE) per l?identificazione di tutte e quattro le paratiroidi, essa è rimasta per anni il tempo obbligato nella chirurgia del pHPT. Poiché più dell?80% dei casi di pHPT è dovuto ad un adenoma paratiroideo singolo, a partire dagli anni Novanta molti si sono interrogati sulla utilità della BNE e hanno proposto, in alternativa, approcci diretti unilaterali, definiti come paratiroidectomie mini-invasive (MIP). In questo lavoro si intende pertanto chiarire quale sia attualmente il ruolo della chirurgia tradizionale (BNE) nel trattamento dell'iperparatiroidismo primitivo

A Synchronous Axial Flux PM Machine d, q Axes Model Which Takes Into Account Iron Losses, Saturation and Temperature Effects on the Windings and the Permanent Magnets

Electrical machine models in which non linear and other second order effects of various nature aren't considered have a limited validity and scope. Adherence to actual machine behaviour is of utmost importance when such models are used to improve design predictions or when they are used in sensitive control applications, such as sensorless control. This paper proposes an evaluation criterion of the most important of these effects in AFPMs and a machine model that takes them into account in order to obtain a better faithfulness to actual machine operation

Brushless AC Drive Using An Axial Flux Synchronous PM Motor With Low Resolution Position Sensors

In this paper a new control scheme for AC brushless drives in which Hall effect sensors are used as rotor position sensors is presented. The proposed control algorithm's most innovative feature is its adaptability to the whole speed range, including start up. A study on the drive's torque ripple has also been carried out and a way to minimize it in all operating conditions has been developed. Finally the algorithm has been implemented and tested in order to drive an axial-flux PM machine for home applications

Axial-Flux Hybrid-Excitation Synchronous Machine: Analysis, Design and Experimental Evaluation

This paper presents an axial-flux machine with hybrid excitation, in which the flux linkage can be regulated in an extremely wide range through an excitation winding. Therefore, this machine shows a theoretically infinite constant power speed range and exhibits also an high degree of fault tolerance against uncontrolled generator operation. The machine has a single-stator double-rotor topology, one rotor mounting permanent magnets and the other supporting an excitation winding. After a review of the state of the art, the paper examines the principle of operation of this machine. Subsequently, a prototype is designed, studied through FEA, and constructed, in order to verify the benefits of the proposed solution