Low-frequency harmonic perturbations drive protein conformational changes

Protein dynamics has been investigated since almost half a century, as it is believed to constitute the fundamental connection between structure and function. Elastic network models (ENMs) have been widely used to predict protein dynamics, flexibility and the biological mechanism, from which remarkable results have been found regarding the prediction of protein conformational changes. Starting from the knowledge of the reference structure only, these conformational changes have been usually predicted either by looking at the individual mode shapes of vibrations (i.e., by considering the free vibrations of the ENM) or by applying static perturbations to the protein network (i.e., by considering a linear response theory). In this paper, we put together the two previous approaches and evaluate the complete protein response under the application of dynamic perturbations. Harmonic forces with random directions are applied to the protein ENM, which are meant to simulate the single frequency-dependent components of the collisions of the surrounding particles, and the protein response is computed by solving the dynamic equations in the underdamped regime, where mass, viscous damping and elastic stiffness contributions are explicitly taken into account. The obtained motion is investigated both in the coordinate space and in the sub-space of principal components (PCs). The results show that the application of perturbations in the low-frequency range is able to drive the protein conformational change, leading to remarkably high values of direction similarity. Eventually, this suggests that protein conformational change might be triggered by external collisions and favored by the inherent low-frequency dynamics of the protein structure

A Mineral Dressing and Economic Study of a Complex Arsenical Ore

The factors that influence the choice of a method for treat­ment of an ore comprise the technical and economic limitations and advantages, derived in detail and balanced according to the exigencies of the particular situation

Sound transmission loss of cross-laminated timber walls: Comparison between measurements carried out in transmission suites and point mobility measurements

The transition from concrete-based to wood-based construction is drawing more attention to the use of cross-laminated timber elements, especially in the building sector. In this context, there is a need to assess the transmission loss performances of such elements already during the research and development phase, when making several tests in sound transmission suites would be overly expensive and time-consuming. The flexural behavior of a composite structure can be determined by point mobility tests. From this kind of measurements, it is possible to estimate the loss factor of the partition and its bending stiffness which, in turn, can be used to determine its sound transmission loss once some basic physical properties are known. In this paper, the sound transmission of cross-laminated timber partitions is obtained with this method. Results are validated by means of measurements in sound transmission suites

Dissenso e magistratura

In questo contributo, gli Autori inquadrano prima da un punto di vista teorico il valore del dissenso all\u2019interno della teoria democratica; passano poi ad indagare quali siano gli effetti benefici del pluralismo e del conflitto inter-istituzionale e intra-istituzionale, soffermandosi poi ad indagare sulle dinamiche di conflitto che coinvolgono l\u2019istituzione giudiziaria (rispetto ad altre istituzioni) e su quelle che si verificano all\u2019interno di questa istituzione. Il contributo si chiude rilevando un apparente paradosso: il dissenso \u2013 pur espletando un\u2019importante funzione di autocorrezione e auto-mutamento all\u2019interno del regime democratico \u2013 rischia, ove esasperati i momenti di conflittualit\ue0, di comportare dei costi sul piano della stessa legittimazione delle istituzioni (e sulla fiducia che, in esse, i cittadini ripongono, come forse avvenuto nel caso del calo di fiducia nella magistratura)