Anomalous Mobility Research Articles

Asymmetric limit cycles within Lorenz chaos induce anomalous mobility for a memory-driven active particle

On applying a small bias force, nonequilibrium systems may respond in paradoxical ways such as with giant negative mobility (GNM)—a large net drift opposite to the applied bias, or giant positive mobility (GPM)—an anomalously large drift in the same direction as the applied bias. Such behaviors have been extensively studied in idealized models of externally driven passive inertial particles. Here, we consider a minimal model of a memory-driven active particle inspired from experiments with walking and superwalking droplets, whose equation of motion maps to the celebrated Lorenz system. By adding a small bias force to this Lorenz model for the active particle, we uncover a dynamical mechanism for simultaneous emergence of GNM and GPM in the parameter space. Within the chaotic sea of the parameter space, a symmetric pair of coexisting asymmetric limit cycles separate and migrate under applied bias force, resulting in anomalous transport behaviors that are sensitive to the active particle's memory. Our work highlights a general dynamical mechanism for the emergence of anomalous transport behaviors for active particles described by low-dimensional nonlinear models. Published by the American Physical Society 2024

Defect related anomalous mobility of small polarons in dielectric oxides at the example of congruent lithium niobate

Polarons play a major role in the description of optical, electrical and dielectrical properties of several ferroelectric oxides. The motion of those particles occurs by elementary hops among the material lattice sites. In order to compute macroscopic transport parameters such as charge mobility, normal (i.e. Fickian) diffusion laws are generally assumed. In this paper we show that when defect states able to trap the polarons for long times are considered, significant deviations from the normal diffusion behaviour arise. As an example of this behavior, we consider here the case of lithium niobate (LN). This can be considered as a prototypical system, having a rich landscape of interacting polaron types and for which a significant wealth of information is available in literature. Our analysis considers the case of a stoichiometric, defect-free lithium niobate containing a certain concentration of small electron polarons hopping on regular Nb sites, and compares it to the material in congruent composition, which is generally found in real-life applications and which is characterized by a large concentration of antisite NbLi defects. While in the first case the charge carriers are free polarons hopping on a regular Nb sublattice, in the second case a fraction of polarons is trapped on antisite defects. Thus, in the congruent material, a range of different hopping possibilities arises, depending on the type of starting and destination sites. We develop a formalism encompassing all these microscopic processes in the framework of a switching diffusion model which can be well approximated by a mobile–immobile transport model providing explicit expressions for the polaron mobility. Finally, starting from the Marcus–Holstein’s model for the polaron hopping frequency we verify by means of a Monte Carlo approach the diffusion/mobility of the different polarons species showing that, while free polarons obey the laws for normal diffusion as expected, bound polarons follow an anomalous diffusion behaviour and that in the case of the congruent crystal where mixed free and bound polaron transport is involved, our expressions indeed provide a satisfactory description.

The effects of roughness of the periodic substrate potential on anomalous mobility

The effects of roughness of the periodic substrate potential on anomalous mobility

Disorder-Induced Anomalous Mobility Enhancement in Confined Geometries.

Strong, scale-free disorder disrupts typical transport properties like the Stokes-Einstein relation and linear response, leading to anomalous diffusion observed in amorphous materials, glasses, living cells, and other systems. Our study reveals that the combination of scale-free quenched disorder and geometrical constraints induces unconventional single-particle mobility behavior. Specifically, in a two-dimensional channel with width w, under external drive, tighter geometrical constraints (smaller w) enhance mobility. We derive an explicit form of the response to an external force by utilizing the double-subordination approach for the quenched trap model. The observed mobility enhancement occurs in the low-temperature regime where the distribution of localization times is scale-free.

Time–Temperature and Time–Electric Field Superposition for Integrated Currents in Polymer Insulating Materials: The Role of Charge Injection and Anomalous Mobility

Time–Temperature and Time–Electric Field Superposition for Integrated Currents in Polymer Insulating Materials: The Role of Charge Injection and Anomalous Mobility

Critical states and anomalous mobility edges in two-dimensional diagonal quasicrystals

We study the single-particle properties of two-dimensional quasicrystals where the underlying geometry of the tight-binding lattice is crystalline but the on-site potential is quasicrystalline. We will focus on the two-dimensional (2D) generalized Aubry-André model which has a varying form to its quasiperiodic potential, through a deformation parameter and varied irrational periods of cosine terms, which allows a continuous family of on-site quasicrystalline models to be studied. We show that the 2D generalized Aubry-André model exhibits many single-particle mobility edges which we confirm for finite systems and supports critical states across large parameter regions. Critical states are neither fully localized nor extended. We observe that diagonal quasicrystalline models can support many energy intervals of critical states in the spectrum while stabilizing both localized and extended states in other energy intervals; we refer to these as anomalous mobility edges. We show that critical states are present independent of system size through a scaling analysis of the inverse participation ratio and that they are present in spectra that also contain extended and localized states, confirming that at least one anomalous mobility edge is present. Due to this, these models exhibit anomalous diffusion of initially localized states across the majority of parameter regions, including deep in the normally localized regime. The presence of critical states in large parameter regimes and throughout the spectrum will have consequences for the many-body properties of quasicrystals, including the formation of the Bose glass and the potential to host a many-body localized phase. Published by the American Physical Society 2024

How the Intrinsically Disordered N-Terminus of Cancer/Testis Antigen MAGEA10 Is Responsible for Its Expression, Nuclear Localisation and Aberrant Migration.

Melanoma-associated antigen A (MAGEA) subfamily proteins are normally expressed in testis and/or placenta. However, aberrant expression is detected in the tumour cells of multiple types of human cancer. MAGEA expression is mainly observed in cancers that have acquired malignant phenotypes, invasiveness and metastasis, and the expression of MAGEA family proteins has been linked to poor prognosis in cancer patients. All MAGE proteins share the common MAGE homology domain (MHD) which encompasses up to 70% of the protein; however, the areas flanking the MHD region vary between family members and are poorly conserved. To investigate the molecular basis of MAGEA10 expression and anomalous mobility in gel, deletion and point-mutation, analyses of the MAGEA10 protein were performed. Our data show that the intrinsically disordered N-terminal domain and, specifically, the first seven amino acids containing a unique linear motif, PRAPKR, are responsible for its expression, aberrant migration in SDS-PAGE and nuclear localisation. The aberrant migration in gel and nuclear localisation are not related to each other. Hiding the N-terminus with an epitope tag strongly affected its mobility in gel and expression in cells. Our results suggest that the intrinsically disordered domains flanking the MHD determine the unique properties of individual MAGEA proteins.

Critical and topological phases of dimerized Kitaev chain in presence of quasiperiodic potential

We investigate localization and topological properties of a dimerized Kitaev chain with $p$-wave superconducting correlations and a quasiperiodically modulated chemical potential. With regard to the localization studies, we demonstrate the existence of distinct phases, such as, the extended phase, the critical (intermediate) phase, and the localized phase that arise due to the competition between the dimerization and the on-site quasiperiodic potential. Most interestingly, the critical phase comprises of two different anomalous mobility edges that are found to exist between the extended to the localized phase, and between the critical (multifractal) and localized phases. We perform our analysis employing the inverse and the normalized participation ratios, fractal dimension, and the level spacing. Subsequently, a finite-size analysis is done to provide support of our findings. Furthermore, we study the topological properties of the zero-energy edge modes via computing the real-space winding number and number of the Majorana zero modes present in the system. We specifically illustrate that our model exhibits a phase transition from a topologically trivial to a nontrivial phase (topological Anderson phase) beyond a critical dimerization strength under the influence of the quasiperiodic potential strength. Finally, in presence of a large potential, we demonstrate that the system undergoes yet another transition from the topologically nontrivial to an Anderson localized phase. Thus, we believe that our results will aid exploration of fundamentally different physics pertaining to the critical and the topological Anderson phases.

962 CASE REPORT: ARRHYTHMIC MITRAL VALVE PROLAPSE - STATE OF THE ART AND WHAT'S NEW

Abstract Background Mitral valve prolapse (MVP) is a well-known pro-arrhythmic condition that involves 2-3% of the general population with an incidence of nonfatal arrhythmic events up to 30% and sudden cardiac death of 2-4% per year. It is assumed that the pro-arrhythmic substrate consists in myocardial fibrosis, secondary to steer-stretch due to the anomalous mobility of the mitral valve apparatus. We still have gaps in the evidences about the arrhythmic risk stratification of MVP and the most appropriate therapy and follow-up. Clinical case We present the case of a 40-years-old man with a known MVP due to Barlow disease, who underwent an at-home resuscitated cardiopulmonary arrest. In hospital, an echocardiogram found left ventricular dilatation with diffuse hypokinesia and severe mitral insufficiency. A coronary angiogram showed an undamaged coronary tree. The 24h ECG monitoring showed very frequent ventricular ectopies and non-sustained ventricular tachycardia. The patient underwent valvular surgery and he is now waiting for cardiac defibrillator (ICD) implantation. Conclusion We discuss the state of the art in risk stratification of “malignant” MVP; the actual and potential future role of the cardiac magnetic resonance, ICD implantation, sympathetic modulation, and early surgical mitral valve repair, in the primary prevention of sudden cardiac death.

Lithium Metal Polymer Batteries: Towards Operation at Ambient Temperature

A canonical electrolyte for lithium metal polymer batteries is PEO (Polyethylene Oxide) doped with lithium salts1. Its ionic conductivity is closely related to the local dynamics (Å, ps) of the polymer chains acting as a solid solvent. For good conductive performances, these batteries must be maintained above the melting point of the bulk PEO (TM =60°C).In order to lower this operating temperature, we propose to use one-dimensional nanoscale confinement to downshift the melting point of the confined electrolyte according to ΔTM ≈ 1/d where d is the pore diameter (Gibbs-Thomson effect)².Porous polymer composite membranes based on vertically aligned Carbon NanoTubes (VA-CNTs)3 ,4 seem to be able to meet this ambitious target. The pores are cylindrical (diameter 4nm, length 100µm) and have the particularity of being all macroscopically oriented and parallel.The effect we are seeking is driven by the curvature of the confining pore. It is then critical to ensure that only the interior of the CNTs is the permeable part of the membrane. We have followed by neutron imaging the time dependence of the penetration of the electrolyte within the membrane. We evidence a critical feature we target: only the interior of the CNTs are the permeable moieties of the membrane.As for the PEO dynamics under confinement, the electrolyte’s multiscale transport properties and ionic conductivity are characterized by PFG-NMR at the micrometer scale and Electrochemical Impedance Spectroscopy (EIS) at the macroscopic scale. We report a conductivity gain of one order of magnitude under VA-CNT confinement.Nevertheless, on a multitude of non-connected CNT pores, conductivity fluctuations are not in phase: by such classical spectroscopic techniques, only an averaged conductivity is measured. To complement the spectroscopic approach, we also probe the system by the Voltage Clamp (also called Single Pore) technique. The analysis of the conductivity noise going through a single CNT pore can indeed reveal whether the conductivity under confinement5 is due to an anomalous mobility and/or charge fluctuations.(1) Xue, Z. et al., Poly(Ethylene Oxide)-Based Electrolytes for Lithium-Ion Batteries. J. Mater. Chem. A 2015, 3 (38), 19218–19253.(2) Alba-Simionesco, C. et al., M. Effects of Confinement on Freezing and Melting. J. Phys.: Condens. Matter 2006, 18 (6), R15–R68.(3) Berrod, Q. et al., Enhanced Ionic Liquid Mobility Induced by Confinement in 1D CNT Membranes. Nanoscale 2016, 8 (15), 7845–7848.(4) Zanotti, J.-M. et al., Nanocomposite membranes for electrochemical devices. Patent WO2016151142 A1.(2016)(5) Tasserit, C. et al., Pink Noise of Ionic Conductance through Single Artificial Nanopores Revisited. Phys. Rev. Lett. 2010, 105 (26), 260602. Figure 1

A vector field approach for identifying anomalous human mobility

AbstractAlthough ordinary human mobility has been extensively studied, anomalous human mobility during emergencies or mass events is not sufficiently understood. The recently proposed vector field approach has shed light on human mobility studies. Here, the authors improve it to analyze anomalous human mobility in mass events. Specifically, the authors develop the anomalous field, the source field, and the dispersion field to identify the crowd gathering location, the start time, and the end time of anomalous human mobility. In addition, the authors propose the decay coefficient and the maximum distance to quantify the influence degree and scope of a mass event. The present approach can be used to capture the spatiotemporal characteristics of human mobility in mass events.

Understanding individual and collective human mobility patterns in twelve crowding events occurred in Shenzhen

Crowding events, which pose tremendous pressure to city management and society safety, are a typical manifestation of anomalous human mobility in metropolitan areas. However, we are still lacking a comprehensive understanding of the anomalous human mobility in crowding events, which is crucial for preventing crowd disasters and developing sustainable cities and societies. In this study, we analyze the individual and collective human mobility patterns in crowding events using the smart card data of six million subway passengers in Shenzhen city. The discovered individual human mobility patterns reveal the underlying mechanism of crowd formation. The discovered collective human mobility patterns can be employed to anticipate crowding events, offering timely information for transportation and crowd management. We analyze the human mobility patterns in twelve crowding events. Individual human mobility patterns reveal the mechanism of crowd formation. Collective human mobility patterns are used to anticipate crowding events.

Anomalous mobility edges in one-dimensional quasiperiodic models

Mobility edges, separating localized from extended states, are known to arise in the single-particle energy spectrum of disordered systems in dimension strictly higher than two and certain quasiperiodic models in one dimension. Here we unveil a different class of mobility edges, dubbed anomalous mobility edges, that separate energy intervals where all states are localized from energy intervals where all states are critical in diagonal and off-diagonal quasiperiodic models. We first introduce an exactly solvable quasi-periodic diagonal model and analytically demonstrate the existence of anomalous mobility edges. Moreover, numerical multifractal analysis of the corresponding wave functions confirms the emergence of a finite energy interval where all states are critical. We then extend the sudy to a quasiperiodic off-diagonal Su-Schrieffer-Heeger model and show numerical evidence of anomalous mobility edges. We finally discuss possible experimental realizations of quasi-periodic models hosting anomalous mobility edges. These results shed new light on the localization and critical properties of low-dimensional systems with aperiodic order.

Computer Vision Technology for Fault Detection Systems Using Image Processing

In the period of Industries 4.0, cyber-physical systems (CPSs) were a major study area. Such systems frequently occur in manufacturing processes and people’s everyday lives, and they communicate intensely among physical elements and lead to inconsistency. Due to the magnitude and importance of the systems they support, the cyber quantum models must function effectively. In this paper, an image-processing-based anomalous mobility detecting approach is suggested that may be added to systems at any time. The expense of glitches, failures or destroyed products is decreased when anomalous activities are detected and unplanned scenarios are avoided. The presently offered techniques are not well suited to these operations, which necessitate information systems for issue treatment and classification at a degree of complexity that is distinct from technology. To overcome such challenges in industrial cyber-physical systems, the Image Processing aided Computer Vision Technology for Fault Detection System (IM-CVFD) is proposed in this research. The Uncertainty Management technique is introduced in addition to achieving optimum knowledge in terms of latency and effectiveness. A thorough simulation was performed in an appropriate processing facility. The study results suggest that the IM-CVFD has a high performance, low error frequency, low energy consumption, and low delay with a strategy that provides. In comparison to traditional approaches, the IM-CVFD produces a more efficient outcome.

Validation of Structural Grounds for Anomalous Molecular Mobility in Ionic Liquid Glasses.

Ionic liquid (IL) glasses have recently drawn much interest as unusual media with unique physicochemical properties. In particular, anomalous suppression of molecular mobility in imidazolium IL glasses vs. increasing temperature was evidenced by pulse Electron Paramagnetic Resonance (EPR) spectroscopy. Although such behavior has been proven to originate from dynamics of alkyl chains of IL cations, the role of electron spin relaxation induced by surrounding protons still remains unclear. In this work we synthesized two deuterated imidazolium-based ILs to reduce electron–nuclear couplings between radical probe and alkyl chains of IL, and investigated molecular mobility in these glasses. The obtained trends were found closely similar for deuterated and protonated analogs, thus excluding the relaxation-induced artifacts and reliably demonstrating structural grounds of the observed anomalies in heterogeneous IL glasses.

Dopant induced anomalous field dependent mobility behavior of poly(3-octylthiophene) devices

Temperature dependent DC current-voltage (I-V) down to 50 K and field-dependent AC impedance measurements were carried out to study the electric field and temperature dependence of charge carrier mobility in Poly(3-octylthiophene) based metal/polymer/metal device structures of different charge carrier concentrations. In highly doped device, a negative field-dependent mobility (NFDM) which vanishes below 150 K was observed whereas a positive field-dependent mobility (PFDM) was observed in moderately doped devices. The observed NFDM is attributed to the low energetic disorder and high positional disorder in the highly doped devices. With further lowering of carrier concentration, charge carrier mobility first decreases with the increase in applied field attaining a minimum value and then increases with the applied field. At higher temperatures (T>150K), all the three devices show thermally-activated process and activation energy increases with lowering the charge carrier concentrations indicating that doping level plays important role in thermally activated transport mechanism. However, in lower temperature (T<100K), activation energy is almost independent of doping level suggesting that injected carrier plays an important role in the lower temperature region. Data from AC impedance measurement also supports the field-dependent mobility model of conduction mechanism in the devices. Analysis of the AC impedance data of the three devices reveals that the equivalent circuit of highly and moderately doped devices is different from that of the low carrier concentration device. The presence of highly energetic disorder in low carrier concentration devices is also confirmed from AC impedance analysis.

Temperature and friction-induced tunable current reversal, anomalous mobility and diffusions

Abstract We numerically investigate the transport properties and dynamic relaxation of a classical inertia Brownian particle in a biased periodic potential under the action of friction and thermal fluctuations. The both fluctuations may be related to friction, thus they may be correlated with each other. We mainly focus on how particle’s transport and dynamic relaxation are affected by fluctuations and the correlation between them. It is unexpected that the combinations of them can tune transport of the particle, including current reversal, and anomalous mobility and diffusions. These results are explained via the stationary probability distributions, which suggest that the bias of the potential can lead to a transition between unimodal and bimodal stationary probability distributions of particle’s velocity. To understand the physical mechanism of these findings, we present dynamic relaxations, namely, the transient probability distributions of velocity and position. These distributions suggest that the motion of the particle is not only related to systematic parameters, but also sensitive to the initial conditions. Our findings may be potentially helpful for research on various transport of the particle and on similar circuits, such as particle separation, Josephson junctions, the phase-locked loops, etc.

Synthesis and characterization of amorphous Fe2.75Dy-oxide thin films demonstrating room-temperature semiconductor, magnetism, and optical transparency

Recently, amorphous/disordered oxide thin films made from Fe and lanthanides like Dy and Tb have been reported to have a rich set of magnetic, optical, and electronic properties, as well as room-temperature magneto-electric coupling with multiferroics [A. Malasi et al., Sci. Rep. 5, 18157 (2015); H. Taz et al., Sci. Rep. 6, 27869 (2016); and H. Taz et al., Sci. Rep. 10, 1–10 (2020)]. Here, we report the synthesis and detailed characterization of Fe2.75Dy-oxide thin films prepared on various substrates using electron beam co-evaporation. The structure, chemistry, electric, magnetic, and optical properties were studied for the as-prepared and annealed (373 K, in air, 1 h) films of thickness 40 nm. High resolution transmission electron microscopy and electron diffraction study showed that the films were amorphous in both the as-prepared and annealed states. The electron energy-loss spectroscopy studies quantified that metal oxygen stoichiometry changed from Fe2.75Dy-O1.5 to Fe2.75Dy-O1.7 upon annealing. Synchrotron-based x-ray absorption spectroscopy investigation confirmed that the as-prepared films were highly disordered with predominantly metallic Fe and Dy states that became slightly oxidized with annealing in air. The as-prepared amorphous films demonstrated significantly high value of ordinary (∼10 cm2/V s) and anomalous (∼102 cm2/V s) Hall mobility and high electrical conductivity of ∼103 S/cm at room temperature. The cryogenic magnetic property measurement shows two-step magnetization below 200 K, suggesting exchange-spring magnetic interaction. The nature of the field cooled and zero-field cooled curves suggested a spin-glass like transition between 78 K and 80 K, with a characteristic broad peak. The Tauc plot analysis from optical transmission spectra confirms the existence of an optical bandgap of ∼2.42 eV that increased slightly to ∼2.48 eV upon annealing. This rich set of transport, optical, and magnetic properties in these thin films is very exciting and points to potential applicability in low-cost multifunctional devices requiring a combination of transparent, semiconducting, and magnetic responses, such as in spintronics.

Evaluating the effect of demographic factors, socioeconomic factors, and risk aversion on mobility during the COVID-19 epidemic in France under lockdown: a population-based study

BackgroundOn March 17, 2020, French authorities implemented a nationwide lockdown to respond to the COVID-19 epidemic and curb the surge of patients requiring critical care. Assessing the effect of lockdown on individual displacements is essential to quantify achievable mobility reductions and identify the factors driving the changes in social dynamics that affected viral diffusion. We aimed to use mobile phone data to study how mobility in France changed before and during lockdown, breaking down our findings by trip distance, user age and residency, and time of day, and analysing regional data and spatial heterogeneities.MethodsFor this population-based study, we used temporally resolved travel flows among 1436 administrative areas of mainland France reconstructed from mobile phone trajectories. Data were stratified by age class (younger than 18 years, 18–64 years, and 65 years or older). We distinguished between residents and non-residents and used population data and regional socioeconomic indicators from the French National Statistical Institute. We measured mobility changes before and during lockdown at both local and country scales using a case-crossover framework. We analysed all trips combined and trips longer than 100 km (termed long trips), and separated trips by daytime or night-time, weekdays or weekends, and rush hours.FindingsLockdown caused a 65% reduction in the countrywide number of displacements (from about 57 million to about 20 million trips per day) and was particularly effective in reducing work-related short-range mobility, especially during rush hour, and long trips. Geographical heterogeneities showed anomalous increases in long-range movements even before lockdown announcement that were tightly localised in space. During lockdown, mobility drops were unevenly distributed across regions (eg, Île-de-France, the region of Paris, went from 585 000 to 117 000 outgoing trips per day). They were strongly associated with active populations, workers employed in sectors highly affected by lockdown, and number of hospitalisations per region, and moderately associated with the socioeconomic level of the regions. Major cities largely shrank their pattern of connectivity, reducing it mainly to short-range commuting (95% of traffic leaving Paris was contained in a 201 km radius before lockdown, which was reduced to 29 km during lockdown).InterpretationLockdown was effective in reducing population mobility across scales. Caution should be taken in the timing of policy announcements and implementation, because anomalous mobility followed policy announcements, which might act as seeding events. Conversely, risk aversion might be beneficial in further decreasing mobility in highly affected regions. We also identified socioeconomic and demographic constraints to the efficacy of restrictions. The unveiled links between geography, demography, and timing of the response to mobility restrictions might help to design interventions that minimise invasiveness while contributing to the current epidemic response.FundingAgence Nationale de la Recherche, EU, REACTing.

Anomalous Electron Transport in One-Dimensional Electron Cyclotron Drift Turbulence

The transverse electron current due to the crossed electric and magnetic fields results in the robust instability driven by the electron $${\mathbf{E}} \times {\mathbf{B}}$$ drift. In the regime of interest for electric propulsion applications, this instability leads to the excitation of quasicoherent nonlinear wave resulting in the anomalous electron transport. We investigate the nonlinear stage of the instability and resulting anomalous electron current using nonlinear Particle-in-Cell simulations. It is found that the anomalous current is proportional to the applied electric field thus demonstrating constant anomalous mobility. Moreover, the scaling of the current density follows the dependence of the dominant resonance wavelength on the electric and magnetic field strength thus clearly demonstrating the cyclotron nature of the instability.