Analysis of heat kernel highlights the strongly modular and heat-preserving structure of proteins

In this paper, we study the structure and dynamical properties of protein contact networks with respect to other biological networks, together with simulated archetypal models acting as probes. We consider both classical topological descriptors, such as the modularity and statistics of the shortest paths, and different interpretations in terms of diffusion provided by the discrete heat kernel, which is elaborated from the normalized graph Laplacians. A principal component analysis shows high discrimination among the network types, either by considering the topological and heat kernel based vector characterizations. Furthermore, a canonical correlation analysis demonstrates the strong agreement among those two characterizations, providing thus an important justification in terms of interpretability for the heat kernel. Finally, and most importantly, the focused analysis of the heat kernel provides a way to yield insights on the fact that proteins have to satisfy specific structural design constraints that the other considered networks do not need to obey. Notably, the heat trace decay of an ensemble of varying-size proteins denotes subdiffusion, a peculiar property of proteins

The Generational Change in Family Businesses: Comparative Analysis between Italy and Peru

The aim of this paper is to understand how family firms in Italy and Peru prepare for generational change, by comparing three companies from each of these countries. After a theoretical analysis, having examined and compared the literature to define the family business, the business family and the generational change, an empirical analysis has been made using a quantitative survey (STEP 2013-2014) and its model, which makes a revision of a set of constructs, to identify if there is transgenerational potential in the business families. From the comparison of the six companies it appears that, contrary to what was initially thought, there are no such relevant differences. They are only diverse approaches to different problems of the same phenomenon. It is concluded that the six companies have an adequate transgenerational potential and are ready for a successful generational change

Non-modulated pyramid wavefront sensor: Why, how and when to use it to sense and correct atmospheric turbulence

Context. The diffusion of adaptive optics systems in astronomical instrumentation for large ground based telescopes is rapidly increasing and the pyramid wavefront sensor is replacing the Shack-Hartmann as standard solution for single conjugate adaptive optics systems. The pyramid wavefront sensor is typically used with a tip/tilt modulation to increase the linearity range of the sensor, but the non-modulated case is interesting because it maximizes the sensor sensitivity. The latter case is generally avoided for the reduced linearity range that prevents robust operation in the presence of atmospheric turbulence. Aims. We aim to solve part of the issues of the non-modulated pyramid wavefront sensor by reducing the model error in the interaction matrix. We linearize the sensor response in the working conditions without extending the sensor linearity range. Methods. We introduce a new calibration approach to model the response of pyramid wave front sensor in partial correction, where the working conditions in the presence of residual turbulence is considered. Results. We show how in simulations, through the new calibration approach, the pyramid wave front sensor without modulation can be used to sense and correct atmospheric turbulence and when this case is preferable to the modulated case.Comment: 12 pages with 18 figures; accepted for publication in A&

Maternal Left Ventricular Function in Uncomplicated Twin Pregnancies: A Speckle-Tracking Imaging Longitudinal Study

Objective: The knowledge of maternal cardiovascular hemodynamic adaptation in twin pregnancies is incomplete. We aimed to longitudinally investigate maternal left ventricular (LV) function in uncomplicated twin pregnancies. Methods: 30 healthy and uncomplicated twin pregnant women and 30 controls with normal singleton pregnancies were prospectively enrolled to undergo transthoracic echocardiography at 10–15 week’s gestation (w) (T1), 19–26 w (T2) and 30–38 w (T3). LV dimensions and volumes, as well as LV ejection fraction (LVEF), mass (LVM) and diastolic parameters (at transmitral pulsed wave Doppler and mitral annular plane tissue Doppler), were calculated. Speckle-tracking imaging was also applied to evaluate LV global longitudinal (GLS), radial and circumferential 2D strains. Results: During twin pregnancy, maternal LV dimensions, volumes and LVM had an increasing trend from T1 to T3, similar to singletons, while LVEF remained stable. There was LV remodeling/hypertrophy in 50% of women at T2 and T3 in both groups. Diastolic function had a worsening trend from T1 to T3 with no differences between twins and singletons, except for higher LV filling pressure (i.e., E/E′) at T2 in twins. Two-dimensional strains did not vary during gestation in either group, except for a linear trend to increase (i.e., worsen) GLS in singletons. Radial and circumferential 2D strains were impaired in about half of the women at each trimester, while GLS was altered in one-fourth/one-third of them in both groups. Conclusion: Maternal LV geometry, dimensions and function are significantly impaired during twin pregnancies, in particular in the second half of gestation, with no significant differences compared to singletons

Numerical control matrix rotation for the LINC-NIRVANA Multi-Conjugate Adaptive Optics system

LINC-NIRVANA will realize the interferometric imaging focal station of the Large Binocular Telescope. A double Layer Oriented multi-conjugate adaptive optics system assists the two arms of the interferometer, supplying high order wave-front correction. In order to counterbalance the field rotation, mechanical derotation for the two ground wave-front sensors, and optical derotators for the mid-high layers sensors fix the positions of the focal planes with respect to the pyramids aboard the wave-front sensors. The derotation introduces pupil images rotation on the wavefront sensors: the projection of the deformable mirrors on the sensor consequently change. The proper adjustment of the control matrix will be applied in real-time through numerical computation of the new matrix. In this paper we investigate the temporal and computational aspects related to the pupils rotation, explicitly computing the wave-front errors that may be generated.Comment: 6 pages, 2 figures, presented at SPIE Symposium "Astronomical Telescopes and Instrumentation'' conference "Adaptive Optics Systems II'',Sunday 27 June 2010, San Diego, California, US

Speckle statistics in adaptive optics images at visible wavelengths

Residual speckles in adaptive optics (AO) images represent a well-known limitation on the achievement of the contrast needed for faint source detection. Speckles in AO imagery can be the result of either residual atmospheric aberrations, not corrected by the AO, or slowly evolving aberrations induced by the optical system. We take advantage of the high temporal cadence (1 ms) of the data acquired by the System for Coronagraphy with High-order Adaptive Optics from R to K bands-VIS forerunner experiment at the Large Binocular Telescope to characterize the AO residual speckles at visible wavelengths. An accurate knowledge of the speckle pattern and its dynamics is of paramount importance for the application of methods aimed at their mitigation. By means of both an automatic identification software and information theory, we study the main statistical properties of AO residuals and their dynamics. We therefore provide a speckle characterization that can be incorporated into numerical simulations to increase their realism and to optimize the performances of both real-time and postprocessing techniques aimed at the reduction of the speckle noise

MAVIS: system modelling and performance prediction

The MCAO Assisted Visible Imager and Spectrograph (MAVIS) Adaptive Optics Module has very demanding goals to support science in the optical: providing 15% SR in V band on a large FoV of 30arcsec diameter in standard atmospheric conditions at Paranal. It will be able to work in closed loop on up to three natural guide stars down to H=19, providing a sky coverage larger than 50% in the south galactic pole. Such goals and the exploration of a large MCAO system parameters space have required a combination of analytical and end- to-end simulations to assess performance, sky coverage and drive the design. In this work we report baseline performance, statistical sky coverage and parameters sensitivity analysis done in the phase-A instrument study.Comment: 12 pages, 9 figures, 7 tables. SPIE conference Astronomical Telescopes and Instrumentation, 14 - 18 December 2020, digital foru