Work and heat probability distribution of an optically driven Brownian particle: Theory and experiments

We analyze the equations governing the evolution of distributions of the work and the heat exchanged with the environment by a manipulated stochastic system, by means of a compact and general derivation. We obtain explicit solutions for these equations for the case of a dragged Brownian particle in a harmonic potential. We successfully compare the resulting predictions with the outcomes of experiments, consisting in dragging a micron-sized colloidal particle through water with a laser trap

Before and after the quarantine: An approximate study on the psychological impact of COVID-19 on the italian population during the lockdown period

COVID-19 (Corona-Virus Disease 2019) in Italy and the measures that were adopted to contain its diffusion had a strong impact on people’s quality of life and mental health. The objective of the study was to quantify the psychological impact of the lockdown period on the general Italian population during the two weeks when the COVID-19 emergency in Italy was at its peak. The study (1556 adults) was conducted from April 6th to April 12th, 2020. A survey was developed through Google Forms in order to assess different psychological measures (Self Efficacy, Locus of Control, Social Connectedness, Sense of Virtual Community, Flourishing, Positive and Negative Affect, Life Satisfaction, and Risk Propensity). The results were then compared to reference data. Thelockdown period increased arousal mainly for negative emotions, but also for positive emotions, and quality of life seemed to be reduced. From a psychosocial point of view, while social connectedness has decreased during lockdown, probably because of isolation and social distancing, the virtual social community seemed to increase in the same period. Interestingly, we revealed how self efficacy increased during the lockdown period, and, at the same time, the Locus of control appeared as externalized, and the risk propensity as reduced. The results are discussed considering previous literature, and a coherent theoretical framework is proposed in order to refine the forecasting model for the psychological impact of the lockdown

Microrheology with optical tweezers: data analysis

We present a data analysis procedure that provides the solution to a long-standing issue in microrheology studies, i.e. the evaluation of the fluids' linear viscoelastic properties from the analysis of a finite set of experimental data, describing (for instance) the time-dependent mean-square displacement of suspended probe particles experiencing Brownian fluctuations. We report, for the first time in the literature, the linear viscoelastic response of an optically trapped bead suspended in a Newtonian fluid, over the entire range of experimentally accessible frequencies. The general validity of the proposed method makes it transferable to the majority of microrheology and rheology techniques

Reconstructing reactivity in dynamic host-guest systems at atomistic resolution: amide hydrolysis under confinement in the cavity of a coordination cage

Spatial confinement is widely employed by nature to attain unique efficiency in controlling chemical reactions. Notable examples are enzymes, which selectively bind reactants and exquisitely regulate their conversion into products. In an attempt to mimic natural catalytic systems, supramolecular metal-organic cages capable of encapsulating guests in their cavity and of controlling/accelerating chemical reactions under confinement are attracting increasing interest. However, the complex nature of these systems, where reactants/products continuously exchange in-and-out of the host, makes it often difficult to elucidate the factors controlling the reactivity in dynamic regimes. As a case study, here we focus on a coordination cage that can encapsulate amide guests and enhance their hydrolysis by favoring their mechanical twisting towards reactive molecular configurations under confinement. We designed an advanced multiscale simulation approach that allows us to reconstruct the reactivity in such host-guest systems in dynamic regimes. In this way, we can characterize amide encapsulation/expulsion in/out of the cage cavity (thermodynamics and kinetics), coupling such host-guest dynamic equilibrium with characteristic hydrolysis reaction constants. All computed kinetic/thermodynamic data are then combined, obtaining a statistical estimation of reaction acceleration in the host-guest system that is found in optimal agreement with the available experimental trends. This shows how, to understand the key factors controlling accelerations/variations in the reaction under confinement, it is necessary to take into account all dynamic processes that occur as intimately entangled in such host-guest systems. This also provides us with a flexible computational framework, useful to build structure-dynamics-property relationships for a variety of reactive host-guest systems

Plasduino: an inexpensive, general purpose data acquisition framework for educational experiments

Based on the Arduino development platform, Plasduino is an open-source data acquisition framework specifically designed for educational physics experiments. The source code, schematics and documentation are in the public domain under a GPL license and the system, streamlined for low cost and ease of use, can be replicated on the scale of a typical didactic lab with minimal effort. We describe the basic architecture of the system and illustrate its potential with some real-life examples.Comment: 11 pages, 10 figures, presented at the XCIX conference of the Societ\`a Italiana di Fisic

Upper Pliocene to Lower Pleistocene volcanic complexes and Upper Neogene deformation in the south-central Andes (36°30′-38°S)

The Agrio (37º51´S-70º26´W), Vilú Mallín (37º28´S-70º45´W), Trohunco (37º18´S-71º01´W), Domuyo (36º38´S-70º26´W) and Los Cardos-Centinela (37º06´S-70º52´W) volcanic complexes in Argentina are the principal Upper Pliocene to Lower Pleistocene volcanic complexes that occur in the Main Andean Cordillera east of the modern volcanic front in Chile, in the Southern Volcanic zone.Volcanic rocks from these centers along with their stratigraphic relations with nearby Neogene volcanic units provide constraints on the age and style of Neogene deformation in the modern backarc of the Southern Volcanic Zone between 36°30´ and 38°S. New and published radiometric ages and stratigraphic and structural relations show that the region was affected by a latest Miocene compressional deformation that took place between 9 and 6.8 Ma.A heterogeneous picture emerges for the younger deformation of the region which lies along the Quaternary orogenic front.The most important structures include a NNW-trending fault system that joins the Trohunco and Los Cardos-Centinela complexes and is characterized by compressive deformation, and a NE-trending extensional fault system along which the Agrio caldera, Vilú Mallín and Domuyo volcanic complexes are aligned. Overall, the backarc in this region was affected by compressional deformation in the late Miocene and subjected to tectonic collapse and transpressional deformation during the late Pliocene to Quaternary.Fil: Miranda, Fernando. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; ArgentinaFil: Folguera Telichevsky, Andres. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Laboratorio de Tectónica Andina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Leal, Pablo Rodrigo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Naranjo, José Antonio. Servicio Nacional de Geología y Minería; ChileFil: Pesce, Abel. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentin

Nature of the constant factor in the relation between radial breathing mode frequency and tube diameter for single-wall carbon nanotubes

Resonance Raman scattering is used to determine the radial breathing mode (RBM) frequency (ωRBM) dependence on tube diameter (dt) for single-wall carbon nanotubes (SWNTs). We establish experimentally the ωRBM=227.0/dt as the fundamental relation for pristine SWNTs. All the other RBM values found in the literature can be explained by an upshift in frequency due mostly to van der Waals interaction between SWNTs and environment

Description of Atmospheric Conditions at the Pierre Auger Observatory Using Meteorological Measurements and Models

Atmospheric conditions at the site of a cosmic ray observatory must be known well for reconstructing observed extensive air showers, especially when measured using the fluorescence technique. For the Pierre Auger Observatory, a sophisticated network of atmospheric monitoring devices has been conceived. Part of this monitoring was a weather balloon program to measure atmospheric state variables above the Observatory. To use the data in reconstructions of air showers, monthly models have been constructed. Scheduled balloon launches were abandoned and replaced with launches triggered by high-energetic air showers as part of a rapid monitoring system. Currently, the balloon launch program is halted and atmospheric data from numerical weather prediction models are used. A description of the balloon measurements, the monthly models as well as the data from the numerical weather prediction are presented

Tocilizumab in MOG-antibody spectrum disorder: a case report

Background: Myelin oligodendrocyte glycoprotein antibody-related spectrum disorders (MOG-SD) are a heterogeneous group of inflammatory demyelinating diseases of the central nervous system, usually responsive to conventional immunosuppressive therapies. However, knowledge about treatment of non-responder patients is scarce. Methods: We report on a 20-year-old MOG-SD patient who experienced clinical deterioration despite rituximab-induced B-cell depletion. Results: Rescue therapy with tocilizumab (TCZ) prevented further relapses, with reduction of spinal-cord load on MRI, and a remarkable reduction of disability at the two-year follow-up. Conclusion: Our observations suggest that TCZ could induce clinico-radiologic improvements, which make it as an option for the treatment of MOG-SD