Drop In Mobility Research Articles

Anti-matching effect in a two dimensional driven vortex lattice in the presence of periodic pinning

The dynamics of a driven superconducting vortex lattice in a two-dimensional (2D) periodic potential of square symmetry is studied using Brownian dynamics simulations. The range and strength of the vortex-substrate interaction are taken to be of the same order as that of the vortex-vortex interaction. The matching effect in a driven vortex lattice in the presence of a periodic array of pinning centers refers to the enhanced resistance to the vortex lattice motion when the ratio of the number of vortices to the number of pinning centers (called the filling fraction) takes simple fractional values. In particular, one expects a pronounced matching effect when the filling fraction is one. Contrary to this expectation, a drop in the vortex lattice mobility is observed as the filling fraction is increased from value one. This anti-matching effect can be understood in terms of the structural change in the vortex lattice as the filling fraction is varied. The dip observed in vortex mobility as a function of temperature when the filling fraction equals one (Joseph T 2020PhysicaA556124737), is studied for other values of filling above and below one. The behavior is found to persist for other fillings as well and is associated with the melting of the vortex lattice. The temperature at which the lattice melts is found to increase with drive and explains the shift in the temperature at which mobility is a minimum, locally.

Disorder-Induced Transition from Transient Quantum Delocalization to Charge Carrier Hopping Conduction in a Nonfullerene Acceptor Material

Nonfullerene acceptors have caused a step change in organic optoelectronics research but little is known about the mechanism and factors limiting charge transport in these molecular materials. Here a joint computational-experimental investigation is presented to understand the impact of various sources of disorder on the electron transport in the nonfullerene acceptor O-IDTBR. We find that in single crystals of this material, electron transport occurs in the transient quantum delocalization regime with the excess charge delocalized over about three molecules on average, according to quantum-classical nonadiabatic molecular-dynamics simulations. In this regime, carrier delocalization and charge mobility (μa=7 cm2 V−1 s−1) are limited by dynamical disorder of off-diagonal and diagonal electron-phonon coupling. In molecular assemblies representing disordered thin films, the additional static disorder of off-diagonal electron-phonon coupling is sufficient to fully localize the excess electron on single molecules, concomitant with a transition of transport mechanism from transient quantum delocalization to small polaron hopping and a drop in electron mobility by about 1 order of magnitude. Yet, inclusion of static diagonal disorder resulting from electrostatic interactions arising from the acceptor-donor-acceptor (A-D-A) structure of O-IDTBR, are found to have the most dramatic impact on carrier mobility, resulting in a further drop of electron mobility by about 4–5 orders of magnitude to 10−5 cm2 V−1 s−1, in good agreement with thin-film electron mobility estimated from space-charge-limited-current measurements. Limitations due to diagonal disorder caused by electrostatic interactions are likely to apply to most nonfullerene acceptors. They imply that while A-D-A or A-DAD-A motifs are beneficial for photoabsorption and exciton transport, the electrostatic disorder they create can limit carrier transport in thin-film optoelectronic applications. This work shows the value of computational methods, in particular, nonadiabatic molecular-dynamics propagation of charge carriers, to distinguish different regimes of transport for different types of molecular packing. Published by the American Physical Society 2024

Charge Carrier Induced Structural Ordering And Disordering in Organic Mixed Ionic Electronic Conductors.

Operational stability underpins the successful application of organic mixed ionic-electronic conductors (OMIECs) in a wide range of fields, including biosensing, neuromorphic computing, and wearable electronics. In this work, both the operation and stability of a p-type OMIEC material of various molecular weights are investigated. Electrochemical transistor measurements reveal that device operation is very stable for at least 300 charging/discharging cycles independent of molecular weight, provided the charge density is kept below the threshold where strong charge-charge interactions become likely. When electrochemically charged to higher charge densities, an increase in device hysteresis and a decrease in conductivity due to a drop in the hole mobility arising from long-range microstructural disruptions are observed. By employing operando X-ray scattering techniques, two regimes of polaron-induced structural changes are found: 1) polaron-induced structural ordering at low carrier densities, and 2) irreversible structural disordering that disrupts charge transport at high carrier densities, where charge-charge interactions are significant. These operando measurements also reveal that the transfer curve hysteresis at high carrier densities is accompanied by an analogous structural hysteresis, providing a microstructural basis for such instabilities. This work provides a mechanistic understanding of the structural dynamics and material instabilities of OMIEC materials during device operation.

Atomic insights into the interaction of N2, CO2, NH3, NO, and NO2 gas molecules with Zn2(V, Nb, Ta)N3 ternary nitride monolayers.

The search for promising carrier blocking layer materials with high stability, including resistance to surface inhibition by environmental molecules that cause a drop in carrier mobility, is critical for the production of tandem solar cells. Based on density functional theory calculations, the reaction of atmospheric gases, including N2, CO2, NH3, NO, and NO2, with three promising Zn2(V, Nb, Ta)N3 monolayers is discovered. The results suggest the chemical adsorption of NH3 and physical adsorption of NO and NO2. In addition, the Zn2(V, Nb, Ta)N3 monolayers are characterized by a weak bonding with N2 and CO2. Charge redistribution is found at the interface between the monolayers and NH3, NO and NO2 molecules, leading to the formation of a local surface dipole that affects the functionality of the Zn2(V, Nb, Ta)N3 monolayers. The Zn2VN3 monolayer is less reactive with atmospheric gases and thus is the most promising for application in tandem solar cells. Notably, the revealed nontrivial behavior of the Zn2(V, Nb, Ta)N3 monolayers towards N-containing gases makes them promising for application in gas sensing. Specifically, the Zn2TaN3 monolayer is the most promising for application in molecular sensing due to its high reversibility and distinguished interaction with NH3, NO, and NO2 gases.

Fluid effects in model granular flows

Pore fluid plays a crucial role in many granular flows, especially those in geophysical settings. However, the transition in behaviour between dry flows and fully saturated flows and the underlying physics that relate to this are poorly understood. In this paper, we report the results of small-scale flume experiments using monodisperse granular particles with varying water content and volume in which the basal pore pressure, total pressure, flow height and velocity profile were measured at a section. We compare the results with theoretical profiles for granular flow and with flow regimes based on dimensional analysis. The runout and the centre of mass were also calculated from the deposit surface profiles. As the initial water content by mass was increased from zero to around 10%, we first observed a drop in mobility by approximately 50%, as surface tension caused cohesive behaviour due to matric suction. As the water content was further increased up to 45%, the mobility also increased dramatically, with increased flow velocity up to 50%, increased runout distance up to 240% and reduced travel angle by up to 10° compared to the dry case. These effects can be directly related to the basal pore pressure, with both negative pressures and positive pore pressures being measured relative to atmospheric during the unsteady flow. We find that the initial flow volume plays a role in the development of relative pore pressure, such that, at a fixed relative water content, larger flows exhibit greater positive pore pressures, greater velocities and greater relative runout distances. This aligns with many other granular experiments and field observations. Our findings suggest that the fundamental role of the pore fluid is to reduce frictional contact forces between grains thus increasing flow velocity and bulk mobility. While this can occur by the development of excess pore pressure, it can also occur where the positive pore pressure is not in excess of hydrostatic, as shown here, since buoyancy and lubrication alone will reduce frictional forces.Graphical abstract

Expected long-term impacts of the COVID-19 pandemic on travel behaviour and online activities: Evidence from a Czech panel survey

The outbreak of the COVID-19 pandemic and the counter-pandemic measures have led to a substantial drop in mobility. The interesting question is whether mobility will return to the pre-pandemic levels after the pandemic or whether at least a part of the change in mobility will be long-lasting. In this paper, we investigate the expected long-term effects of the COVID-19 pandemic on work from home and online shopping. Using individual responses from panel data collected among the Czech adult urban population in four waves during 2020 and 2021, we expect a long-term increase in work from home and online shopping relative to the pre-pandemic levels. The number of physical trips to work and shops is expected to decrease. The main determinants of work from home are job type, industry and education. The main determinants of online shopping are age and education. The strength of influence of these determinants on the expected frequency of online activities after the pandemic differs from their impact before the pandemic. The expected modal split for commuting to work and for out-of-home shopping stays virtually unchanged relative to the situation before the pandemic.

A data fusion approach with mobile phone data for updating travel survey-based mode split estimates

Up-to-date information on different modes of travel to monitor transport traffic and evaluate rapid urban transport planning interventions is often lacking. Transport systems typically rely on traditional data sources providing outdated mode-of-travel data due to their data latency, infrequent data collection and high cost. To address this issue, we propose a method that leverages mobile phone data as a cost-effective and rich source of geospatial information to capture current human mobility patterns at unprecedented spatiotemporal resolution. Our approach employs mobile phone application usage traces to infer modes of transportation that are challenging to identify (bikes and ride-hailing/taxi services) based on mobile phone location data. Using data fusion and matrix factorisation techniques, we integrate official data sources (household surveys and census data) with mobile phone application usage data. This integration enables us to reconstruct the official data and create an updated dataset that incorporates insights from digital footprint data from application usage. We illustrate our method using a case study focused on Santiago, Chile successfully inferring four modes of transportation: mass-transit (all public transportation), motorised (cars and similar vehicles), active (pedestrian and cycle trips), and taxi (traditional taxi and ride-hailing services). Our analysis revealed significant changes in transportation patterns between 2012 and 2020. We quantify a reduction in mass-transit usage across municipalities in Santiago, except where metro/rail lines have been more recently introduced, highlighting added resilience to the public transport network of these infrastructure enhancements. Additionally, we evidence an overall increase in motorised transport throughout Santiago, revealing persistent challenges in promoting urban sustainable transportation. Findings also point to a rise in the share of taxi usage, and a drop in active mobility, suggesting a modal shift towards less sustainable modes of travel. We validate our findings comparing our updated estimates with official smart card transaction data. The consistency of findings with expert domain knowledge from the literature and historical transport usage trends further support the robustness of our approach.

Getting Back on Track: Understanding COVID-19 Impact on Urban Mobility and Segregation with Location Service Data

Understanding the impact of COVID-19 on urban life rhythms is crucial for accelerating the return-to-normal progress and envisioning more resilient and inclusive cities. While previous studies either depended on small-scale surveys or focused on the response to initial lockdowns, this paper uses large-scale location service data to systematically analyze the urban mobility behavior changes across three distinct phases of the pandemic, i.e., pre-pandemic, lockdown, and reopen. Our analyses reveal two typical patterns that govern the mobility behavior changes in most urban venues: daily life-centered urban venues go through smaller mobility drops during the lockdown and more rapid recovery after reopening, while work-centered urban venues suffer from more significant mobility drops that are likely to persist even after reopening. Such mobility behavior changes exert deeper impacts on the underlying social fabric, where the level of mobility reduction is positively correlated with the experienced segregation at that urban venue. Therefore, urban venues undergoing more mobility reduction are also more filled with people from homogeneous socio-demographic backgrounds. Moreover, mobility behavior changes display significant heterogeneity across geographical regions, which can be largely explained by the partisan inclination at the state level. Our study shows the vast potential of location service data in deriving a timely and comprehensive understanding of the social dynamic in urban space, which is valuable for informing the gradual transition back to the normal lifestyle in a “post-pandemic era”.

MP72-14 SOCIAL INCENTIVES AND GAMIFICATION IMPROVE MOBILITY AFTER RADICAL CYSTECTOMY FOR PATIENTS WITH LOW SOCIAL SUPPORT

You have accessJournal of UrologyCME1 Apr 2023MP72-14 SOCIAL INCENTIVES AND GAMIFICATION IMPROVE MOBILITY AFTER RADICAL CYSTECTOMY FOR PATIENTS WITH LOW SOCIAL SUPPORT Hanna Jia, Lei Lei Xia, Esther Nivasch, Shirley Wang, Victor Rivera, Charles Rarehide, George Lin, Thomas Guzzo, Ryan Greysen, and Daniel Lee Hanna JiaHanna Jia More articles by this author , Lei Lei XiaLei Lei Xia More articles by this author , Esther NivaschEsther Nivasch More articles by this author , Shirley WangShirley Wang More articles by this author , Victor RiveraVictor Rivera More articles by this author , Charles RarehideCharles Rarehide More articles by this author , George LinGeorge Lin More articles by this author , Thomas GuzzoThomas Guzzo More articles by this author , Ryan GreysenRyan Greysen More articles by this author , and Daniel LeeDaniel Lee More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003340.14AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Patient mobility after major abdominal surgery is a key factor in postoperative outcomes and readmissions. Gamification with social incentives may improve mobility for hospitalized medical patients. We evaluated this approach to improve post-operative mobility in patients undergoing major abdominal surgery such as radical cystectomy. METHODS: This was a randomized clinical trial with enrollment from 1/2020 to 9/2021 at a single institution. All participants received a FitBit device. The control group received feedback from the device, whereas the intervention group entered a game that continued for 12 weeks after discharge. The game assigned points and levels for achieving step goals that were reinforced by a support partner who received live updates on the progress of the patient. Each participant in the intervention group was given a new goal each week to increase 10%. RESULTS: 61 patients were enrolled, with 30 in the intervention arm and 31 in the control arm. Overall, the average preoperative step count per day was 5385 (SD 3536), decreasing to an average of 777 (SD 1265) steps per day postoperatively, increasing to 6082 steps per day (SD 3742) by 12 weeks. The intervention group had an average+793 more steps (95% CI -446, 2031) compared to control at the end of the 12-week post-discharge period, but the difference was not statistically significant (p=0.21). For patients who had a significant drop in mobility from their preoperative baseline, defined as more>60% decrease in steps during their first week after discharge, we found that intervention participants had+1735 more steps than the control arm (p=0.015) at the end of the 12-week post-discharge period. Those who reported lower levels of social support had significantly higher step counts with the intervention compared to the control. Those in the intervention also reported significantly lower 30-day complication rates (16.7%) than those in the control arm (32.3%, p=0.02). CONCLUSIONS: Gamification with social incentives did not improve mobility for all participants, but did significantly improve mobility for at-risk populations such as those who had significant post-operative mobility declines, and those with low social support. Complication rates were lower for those in the gamification and incentives intervention. Although promising, larger randomized mobility trials may need to target at-risk populations to impact mobility outcomes after major abdominal surgery. Source of Funding: none © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1030 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hanna Jia More articles by this author Lei Lei Xia More articles by this author Esther Nivasch More articles by this author Shirley Wang More articles by this author Victor Rivera More articles by this author Charles Rarehide More articles by this author George Lin More articles by this author Thomas Guzzo More articles by this author Ryan Greysen More articles by this author Daniel Lee More articles by this author Expand All Advertisement PDF downloadLoading ...

Melting, reentrant ordering and peak effect for Wigner crystals with quenched and thermal disorder

We consider simulations of Wigner crystals in solid state systems interacting with random quenched disorder in the presence of thermal fluctuations. When quenched disorder is absent, there is a well defined melting temperature determined by the proliferation of topological defects, while for zero temperature, there is a critical quenched disorder strength above which topological defects proliferate. When both thermal and quenched disorder are present, these effects compete, and the thermal fluctuations can reduce the effectiveness of the quenched disorder, leading to a reentrant ordered phase in agreement with the predictions of Nelson (1983 Phys. Rev. B 27 2902–14). There are two competing theories for the low temperature behavior, and our simulations show that both capture aspects of the actual response. The critical disorder strength separating ordered from disordered states remains finite as the temperature goes to zero, as predicted by Cha and Fertig (1995 Phys. Rev. Lett. 74 4867–70), instead of dropping to zero as predicted by Nelson. At the same time, the critical disorder strength decreases with decreasing temperature, as predicted by Nelson, instead of remaining constant, as predicted by Cha and Fertig. The onset of the reentrant phase can be deduced based on changes in the transport response, where the reentrant ordering appears as an increase in the mobility or the occurrence of a depinning transition. We also find that when the system is in the ordered state and thermally melts, there is an increase in the effective damping or pinning. This produces a drop in the electron mobility that is similar to the peak effect phenomenon found in superconducting vortices, where thermal effects soften the lattice or break down its elasticity, allowing the particles to better adjust their positions to take full advantage of the quenched disorder.

Electric field induced non-monotonic electron transport in pseudomorphic Al0.3Ga0.7As/In0.15Ga0.85As coupled quantum well structure

In this article, the non-monotonic electron mobility (μ) is modulated by applying an external electric field (Fext) in pseudomorphic Al0.3Ga0.7As/In0.15Ga0.85As asymmetric coupled quantum well (ACQW) structure. The structural asymmetry is achieved through dissimilar doping in the side barriers. Application of a specific Fext (here, Fext = 6.66 kV/cm) makes the proposed structure potentially symmetric causing resonance of subband states (RSS) between the wells. Near resonance, the drastic change in the distribution of subband wave functions leads to cusp like variation of the scattering rate matrix elements resulting non-monotonic nature of μ. We show that the variation of μ is mostly due to the ionized impurity scattering mediated by intersubband effects. However, there is a sudden drop in mobility due to interface roughness scattering i.e., μir at RSS and subsequently, it reduces the overall magnitude of μ. We show that μ can be enhanced with a sharp drop at the resonance point by increasing the well width, central barrier width, spacer width, or doping region width of the proposed structure. The results obtained can be utilized to improve the performance of negative resistance based low dimensional device structures.

Long-term impacts of the COVID-19 pandemic on mobility and online activities – the case of Czech respondents

The outbreak of the COVID-19 pandemic and the counter-pandemic measures have led to a substantial drop in people's mobility. The interesting question is whether mobility after the pandemic will return to the pre-pandemic levels or whether the change in mobility will be more enduring.In this paper, we investigate the permanent effects of the COVID-19 pandemic on teleworking and online shopping. Using panel data collected among the Czech adult urban population in four waves during 2020 and 2021, we find that teleworking and online shopping are expected to increase relative to the pre-pandemic levels even after the pandemic. The number of trips to work and out-of-home shopping is expected to decrease. The main determinants of teleworking are job type, industry and education. The main determinants of online shopping are age and education.

Carrier Mobility Modulation in Cu2Se Composites Using Coherent Cu4TiSe4 Inclusions Leads to Enhanced Thermoelectric Performance

Carrier transport engineering in bulk semiconductors using inclusion phases often results in the deterioration of carrier mobility (μ) owing to enhanced carrier scattering at phase boundaries. Here, we show by leveraging the temperature-induced structural transition between the α-Cu2Se and β-Cu2Se polymorphs that the incorporation of Cu4TiSe4 inclusions within the Cu2Se matrix results in a gradual large drop in the carrier mobility at temperatures below 400 K (α-Cu2Se), whereas the carrier mobility remains unchanged at higher temperatures, where the β-Cu2Se polymorph dominates. The sharp discrepancy in the electronic transport within the α-Cu2Se and β-Cu2Se matrices is associated with the formation of incoherent α-Cu2Se/Cu4TiSe4 interfaces, owing to the difference in their atomic structures and lattice parameters, which results in enhanced carrier scattering. In contrast, the similarity of the Se sublattices between β-Cu2Se and Cu4TiSe4 gives rise to coherent phase boundaries and good band alignment, which promote carrier transport across the interfaces. Interestingly, the different cation arrangements in Cu4TiSe4 and β-Cu2Se contribute to enhanced phonon scattering at the interfaces, which leads to a reduction in the lattice thermal conductivity. The large reduction in the total thermal conductivity while preserving the high power factor of β-Cu2Se in the (1-x)Cu2Se/(x)Cu4TiSe4 composites results in an improved ZT of 1.2 at 850 K, with an average ZT of 0.84 (500-850 K) for the composite with x = 0.01. This work highlights the importance of structural similarity between the matrix and inclusions when designing thermoelectric materials with improved energy conversion efficiency.

Scattering Analysis of AlGaN/AlN/GaN Heterostructures with Fe-Doped GaN Buffer.

The results of the study of the influence of Fe segregation into the unintentionally doped GaN channel layer in AlGaN/AlN/GaN heterostructures with Fe-doped GaN buffer layer on the electrical properties of two-dimensional electron gas are presented. A set of several samples was grown by metal-organic vapor-phase epitaxy and characterized by the van der Pauw method. The dependence of concentration and mobility of the two-dimensional electron gas on the channel layer thickness was analyzed theoretically by self-consistent solving of 1D Poisson and Schrödinger equations and scattering rate calculations within the momentum relaxation time approximation. It was found that both concentration and mobility decreases were responsible for the increase in the sheet resistance in the structures with a thinner channel layer, with a drop in mobility being not only due to ionized impurity scattering, but also due to a combined effect of weakening of screening, lower carrier energy and change in form-factors on scattering by interface roughness, dislocations and polar optical phonons.

Study of nonmonotonic electron mobility due to influence of asymmetric structure parameters in pseudomorphic heterojunction field effect transistors

Nonmonotonic electron mobility is obtained in InxGa1-xAs/GaAs double quantum well pseudomorphic heterostructure field effect transistor by changing the structure parameters. We show that a rapid drop in mobility occurs at the point of resonance of sub-band states due to asymmetric variation of doping concentrations. The sub-band wave function distributions change significantly near the resonance and influence the sub-band mobilities through the scattering potentials, there by causing the dip in μ. The depth of nonlinearity in μ enhances by increasing the central barrier width and the difference between the well widths. On the other hand, variation of μ as a function of asymmetric change of well widths leads to a hump like raise in μ under unequal doping concentrations. Our results of nonlinear mobility can be utilized in low temperature transistor applications.

A realistic model of temperature dependent carrier diffusion constant in MAPbI3 films

The charge carrier mobility in perovskites is known to be affected by temperature. However, at low temperatures the perovskite film bears interfacial strains by deformation between the film and its substrate with difference coefficients of thermal expansion. Herein we provide a more realistic temperature-dependent carrier dynamics model involving both interfacial strain effect and intrinsic optoelectronic properties. The interfacial strain of a MAPbI3 film is confirmed through in-situ temperature-dependent X-ray diffractions. The carrier dynamics at different temperatures are unraveled using carrier dynamics fittings to time-resolved photoluminescence decays. An abnormal drop in carrier mobility is revealed with continuously decreasing temperature. The strain affects the trap density in films thus declines the carrier mobility at low temperatures. The carrier losses at the buried surface become significant at low temperatures due to the interfacial strain. This work provides a reminder that substrates should be carefully considered in temperature-related applications of perovskites.

The impact of state paid sick leave policies on weekday workplace mobility during the COVID-19 pandemic

ObjectivesThis study aimed to evaluate whether the Families First Coronavirus Response Act (FFCRA) modified the association between pre-existing state paid sick leave (PSL) and weekday workplace mobility between February 15 and July 7, 2020. Study designThis was a longitudinal, observational study. MethodsThe 50 US states and Washington, D.C., were divided into exposure groups based on the presence or absence of pre-existing state PSL policies. Derived from Google COVID-19 Community Mobility Reports, the outcome was measured as the daily percent change in weekday workplace mobility. Mixed-effects, interrupted time series regression was performed to evaluate weekday workplace mobility after the implementation of the FFCRA on April 1, 2020. ResultsStates with pre-existing PSL policies exhibited a greater drop in mobility following the passage of the FFCRA (β = −8.86, 95% confidence interval: −11.6, −6.10, P < 001). This remained significant after adjusting for state-level health, economic, and sociodemographic indicators (β = −3.13, 95% confidence interval: −5.92, −0.34; P = .039). ConclusionsPre-existing PSL policies were associated with a significant decline in weekday workplace mobility after the FFCRA, which may have influenced local health outcomes. The presence of pre-existing state policies may differentially influence the impact of federal legislation enacted during emergencies.

Self-localized electron state in a dense helium gas: Variational and self-consistent approaches

Using the variational and self-consistent approaches, the possibility of the formation of a self-localized polaronic state of an electron in a helium vapor under an increase in its density with increasing temperature is studied. It is shown that such a state arises when the temperature reaches a certain characteristic value. It has been established that, when the trial wave function of a localized electron is chosen in the form of a Gaussian distribution, the procedure for minimizing the free energy of the system leads to a self-localized state formation temperature close to that at which a sharp drop in the charge mobility with increasing temperature is experimentally recorded. It is shown that the application of a self-consistent approach based on the joint solution of the wave equation for an electron and the equation for the density of the surrounding vapor leads to qualitatively the same results as the variational method, although with a higher polaronic state formation temperature.

Did earnings mobility change after minimum wage introduction? Evidence from parametric and semi‐nonparametric methods in Germany

SummaryWe analyze the evolution of earnings mobility in Germany between 2011 and 2018. We use transition matrices and parametric and semi‐nonparametric copula models to assess the impact of the introduction of the national minimum wage on January 1, 2015, on individual positional persistence in the wage distribution. We find a drop in mobility at the bottom of the distribution. This is confirmed both by the parametric and the semi‐nonparametric methods used. Prediction accuracy of the semi‐nonparametric model is higher than that of the fully parametric model.

Oscillations of Drops with Mobile Contact Lines on the International Space Station: Elucidation of Terrestrial Inertial Droplet Spreading.

We analyze shape oscillations of sessile water drops with fully mobile contact lines (CL) aboard the International Space Station. The unique microgravity environment enables the study of centimeter-sized droplets with associated inertial-capillary motions. Plane-normal substrate vibrations induce resonance behaviors quantified by frequency scans from which the natural frequencies and mode shapes are identified for nine different hydrophobic surfaces. Experimental observations agree well with, and validate, a recent spectral prediction of mobile CL sessile drop oscillations. The experimental findings help elucidate terrestrial droplet inertial spreading, a poorly understood phenomenon pervasive in many processes.