scholarly journals The Role of Data in Model Building and Prediction: A Survey Through Examples

Entropy ◽  
2018 ◽  
Vol 20 (10) ◽  
pp. 807 ◽  
Author(s):  
Marco Baldovin ◽  
Fabio Cecconi ◽  
Massimo Cencini ◽  
Andrea Puglisi ◽  
Angelo Vulpiani
Keyword(s):  
Dynamical Systems ◽  
Model Building ◽  
Spatial Scales ◽  
Gain Control ◽  
Short Review ◽  
Minimal Amount ◽  
Many Body ◽  
Model Free ◽  
Many Body Systems

The goal of Science is to understand phenomena and systems in order to predict their development and gain control over them. In the scientific process of knowledge elaboration, a crucial role is played by models which, in the language of quantitative sciences, mean abstract mathematical or algorithmical representations. This short review discusses a few key examples from Physics, taken from dynamical systems theory, biophysics, and statistical mechanics, representing three paradigmatic procedures to build models and predictions from available data. In the case of dynamical systems we show how predictions can be obtained in a virtually model-free framework using the methods of analogues, and we briefly discuss other approaches based on machine learning methods. In cases where the complexity of systems is challenging, like in biophysics, we stress the necessity to include part of the empirical knowledge in the models to gain the minimal amount of realism. Finally, we consider many body systems where many (temporal or spatial) scales are at play—and show how to derive from data a dimensional reduction in terms of a Langevin dynamics for their slow components.

scholarly journals Universal relations for ultracold reactive molecules

2020 ◽  
Vol 6 (51) ◽  
pp. eabd4699
Author(s):  
Mingyuan He ◽  
Chenwei Lv ◽  
Hai-Qing Lin ◽  
Qi Zhou
Keyword(s):  
Critical Role ◽  
Interaction Strength ◽  
Quantum Correlations ◽  
Polar Molecules ◽  
Many Body ◽  
Density Correlation ◽  
Ultracold Polar Molecules ◽  
Unexplored Area ◽  
Many Body Systems

The realization of ultracold polar molecules in laboratories has pushed physics and chemistry to new realms. In particular, these polar molecules offer scientists unprecedented opportunities to explore chemical reactions in the ultracold regime where quantum effects become profound. However, a key question about how two-body losses depend on quantum correlations in interacting many-body systems remains open so far. Here, we present a number of universal relations that directly connect two-body losses to other physical observables, including the momentum distribution and density correlation functions. These relations, which are valid for arbitrary microscopic parameters, such as the particle number, the temperature, and the interaction strength, unfold the critical role of contacts, a fundamental quantity of dilute quantum systems, in determining the reaction rate of quantum reactive molecules in a many-body environment. Our work opens the door to an unexplored area intertwining quantum chemistry; atomic, molecular, and optical physics; and condensed matter physics.

scholarly journals On the widths and binding energies of K− nuclear states and the role of K− multi-nucleon interactions

2018 ◽  
Vol 181 ◽  
pp. 01009
Author(s):  
Jaroslava Hrtankova ◽  
Jiří Mareš
Keyword(s):  
Bound States ◽  
Binding Energies ◽  
Many Body ◽  
Nucleon Interaction ◽  
Substantial Impact ◽  
Coupled Channels ◽  
Self Consistent ◽  
Interaction Term ◽  
Many Body Systems

We report on our recent self-consistent calculations of K− nuclear quasi-bound states using K− optical potentials derived from chirally motivated meson-baryon coupled channels models [1, 2]. The K− single-nucleon potentials were supplemented by a phenomenological K− multi-nucleon interaction term introduced to achieve good fits to K− atom data. We demonstrate a substantial impact of the K− multi-nucleon absorption on the widths of K− nuclear states. If such states ever exist in nuclear many-body systems, their widths are excessively large to allow observation.

scholarly journals Two- and three-body contacts in the unitary Bose gas

Science ◽  
2017 ◽  
Vol 355 (6323) ◽  
pp. 377-380 ◽  
Author(s):  
Richard J. Fletcher ◽  
Raphael Lopes ◽  
Jay Man ◽  
Nir Navon ◽  
Robert P. Smith ◽  
...  
Keyword(s):  
Bose Gas ◽  
Many Body ◽  
Body Contact ◽  
Wide Range ◽  
Pairwise Correlations ◽  
Efimov Physics ◽  
Many Body Systems ◽  
Three Body ◽  
Profound Insight

In many-body systems governed by pairwise contact interactions, a wide range of observables is linked by a single parameter, the two-body contact, which quantifies two-particle correlations. This profound insight has transformed our understanding of strongly interacting Fermi gases. Using Ramsey interferometry, we studied coherent evolution of the resonantly interacting Bose gas, and we show here that it cannot be explained by only pairwise correlations. Our experiments reveal the crucial role of three-body correlations arising from Efimov physics and provide a direct measurement of the associated three-body contact.

scholarly journals Persistent and prolonged cough in children: differential diagnosis and treatment algorithms

2019 ◽  
pp. 58-75
Author(s):  
Yu. L. Mizernitskiy ◽  
I. M. Melnikova
Keyword(s):  
Diagnosis And Treatment ◽  
Complex Mechanism ◽  
Many Body ◽  
Treatment Algorithms ◽  
Cough Reflex ◽  
Modern Methods ◽  
Many Body Systems ◽  
Combined Drugs ◽  
Antitussive Drugs

The article presents data on the etiology, modern methods for diagnosis and treatment of respiratory system diseases and examines in detail cough as the main symptom. Particular attention is paid to hypertussivity, which is defined as a cough that occurs in the absence of obvious reasons. In addition, the emphasize was put on the role of anatomical and physiological features in the development and characteristics of cough, especially in young children. The authors draw attention to the complex mechanism of the cough, which development involves many body systems such as nervous, immune, endocrine and respiratory. The article describes the main treatment methods, drugs prescribed to the patients with cough, which are divided into «antitussive» drugs used as cough suppressants and «protussive» drugs used in situations, in which mobilization of secretions is desired, combined drugs. The role of new combined drugs, in particular, Rengalin, which affects the central and peripheral links of the cough reflex, was noted.

scholarly journals NADPH Oxidase Deficiency: A Multisystem Approach

2017 ◽  
Vol 2017 ◽  
pp. 1-23 ◽  
Author(s):  
Giuliana Giardino ◽  
Maria Pia Cicalese ◽  
Ottavia Delmonte ◽  
Maddalena Migliavacca ◽  
Boaz Palterer ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Protective Role ◽  
Biological Processes ◽  
The Novel ◽  
Many Body ◽  
Phagocytic Cells ◽  
Oxidase Deficiency ◽  
Oxidative Balance ◽  
Many Body Systems

The immune system is a complex system able to recognize a wide variety of host agents, through different biological processes. For example, controlled changes in the redox state are able to start different pathways in immune cells and are involved in the killing of microbes. The generation and release of ROS in the form of an “oxidative burst” represent the pivotal mechanism by which phagocytic cells are able to destroy pathogens. On the other hand, impaired oxidative balance is also implicated in the pathogenesis of inflammatory complications, which may affect the function of many body systems. NADPH oxidase (NOX) plays a pivotal role in the production of ROS, and the defect of its different subunits leads to the development of chronic granulomatous disease (CGD). The defect of the different NOX subunits in CGD affects different organs. In this context, this review will be focused on the description of the effect of NOX2 deficiency in different body systems. Moreover, we will also focus our attention on the novel insight in the pathogenesis of immunodeficiency and inflammation-related manifestations and on the protective role of NOX2 deficiency against the development of atherosclerosis.

scholarly journals Time Quasilattices in Dissipative Dynamical Systems

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Felix Flicker
Keyword(s):  
Dynamical Systems ◽  
Discrete Time ◽  
Degrees Of Freedom ◽  
Period Doubling ◽  
Periodic Lattice ◽  
Many Body ◽  
Periodically Driven ◽  
Unit Cells ◽  
Many Body Systems ◽  
Dissipative Dynamical Systems

We establish the existence of ‘time quasilattices’ as stable trajectories in dissipative dynamical systems. These tilings of the time axis, with two unit cells of different durations, can be generated as cuts through a periodic lattice spanned by two orthogonal directions of time. We show that there are precisely two admissible time quasilattices, which we term the infinite Pell and Clapeyron words, reached by a generalization of the period-doubling cascade. Finite Pell and Clapeyron words of increasing length provide systematic periodic approximations to time quasilattices which can be verified experimentally. The results apply to all systems featuring the universal sequence of periodic windows. We provide examples of discrete-time maps, and periodically-driven continuous-time dynamical systems. We identify quantum many-body systems in which time quasilattices develop rigidity via the interaction of many degrees of freedom, thus constituting dissipative discrete ‘time quasicrystals’.

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