Active crystallization from power functional theory.

We address the gas, liquid, and crystal phase behaviors of active Brownian particles in three dimensions. The nonequilibrium force balance at coexistence leads to equality of state functions for which we use power functional approximations. Motility-induced phase separation starts at a critical point and quickly becomes metastable against active freezing for Péclet numbers above a nonequilibrium triple point. The mean swim speed acts as a state variable, similar to the density of depletion agents in colloidal demixing. We obtain agreement with recent simulation results and correctly predict the strength of particle number fluctuations in active fluids.

Why neural functionals suit statistical mechanics.

We describe recent progress in the statistical mechanical description of many-body systems via machine learning combined with concepts from density functional theory and many-body simulations. We argue that the neural functional theory by Sammülleret al(2023Proc. Natl Acad. Sci.120e2312484120) gives a functional representation of direct correlations and of thermodynamics that allows for thorough quality control and consistency checking of the involved methods of artificial intelligence. Addressing a prototypical system we here present a pedagogical application to hard core particle in one spatial dimension, where Percus' exact solution for the free energy functional provides an unambiguous reference. A corresponding standalone numerical tutorial that demonstrates the neural functional concepts together with the underlying fundamentals of Monte Carlo simulations, classical density functional theory, machine learning, and differential programming is available online athttps://github.com/sfalmo/NeuralDFT-Tutorial.

Neural functional theory for inhomogeneous fluids: Fundamentals and applications.

We present a hybrid scheme based on classical density functional theory and machine learning for determining the equilibrium structure and thermodynamics of inhomogeneous fluids. The exact functional map from the density profile to the one-body direct correlation function is represented locally by a deep neural network. We substantiate the general framework for the hard sphere fluid and use grand canonical Monte Carlo simulation data of systems in randomized external environments during training and as reference. Functional calculus is implemented on the basis of the neural network to access higher-order correlation functions via automatic differentiation and the free energy via functional line integration. Thermal Noether sum rules are validated explicitly. We demonstrate the use of the neural functional in the self-consistent calculation of density profiles. The results outperform those from state-of-the-art fundamental measure density functional theory. The low cost of solving an associated Euler-Lagrange equation allows to bridge the gap from the system size of the original training data to macroscopic predictions upon maintaining near-simulation microscopic precision. These results establish the machine learning of functionals as an effective tool in the multiscale description of soft matter.

Noether-Constrained Correlations in Equilibrium Liquids.

Liquid structure carries deep imprints of an inherent thermal invariance against a spatial transformation of the underlying classical many-body Hamiltonian. At first order in the transformation field Noether's theorem yields the local force balance. Three distinct two-body correlation functions emerge at second order, namely the standard two-body density, the localized force-force correlation function, and the localized force gradient. An exact Noether sum rule interrelates these correlators. Simulations of Lennard-Jones, Yukawa, soft-sphere dipolar, Stockmayer, Gay-Berne and Weeks-Chandler-Andersen liquids, of monatomic water and of a colloidal gel former demonstrate the fundamental role in the characterization of spatial structure.

Physical activity promotion in daycare centres in Germany: study protocol for a cross-sectional survey within the BeweKi study.

INTRODUCTION: In Germany, a total of 92.2% of children between the age of 3 and school entry age attend daycare centres. Therefore, daycare centres are a suitable setting to promote physical activity among children. Yet, there is a lack of knowledge on the promotion of physical activity in daycare centres with regards to different structures and concepts, culture/policies/practices and the characteristics of directors and pedagogical staff of daycare centres in Germany. The aim of this study is to investigate (a) the status quo, as well as (b) the fostering and hindering conditions (barriers and facilitators) of physical activity promotion in daycare centres in Germany. METHODS AND ANALYSIS: The cross-sectional study will collect data from November 2022 to February 2023. For the sample, about 5500 daycare centres will be drawn from an address database available through the German Youth Institute (DJI) and invited to the survey. From each daycare centre a director and a pedagogical staff member will be asked to fill in a standardised self-administered questionnaire. The survey explores characteristics of the daycare centre and the implementation of physical activity promotion, for example, the extent and form of physical activity promotion, the use and size of indoor and outdoor area, structural conditions such as personal and financial resources, personal attitudes towards physical activity promotion, demographic characteristics of pedagogical staff, structural daycare centre's characteristics such as proportion of children from socioeconomic disadvantaged groups. In addition, micro-geographical data on socioeconomic and infrastructural environment of the daycare centres will be included in the data set. ETHICS AND DISSEMINATION: The study has been received and approved by the Commissioner for Data Protection of the Robert Koch Institute and by the Ethics Committee of Alice Salomon Hochschule Berlin, University of Applied Sciences. Results will be disseminated through publications and presentations to scientific community and stakeholders.

Perspective: How to overcome dynamical density functional theory.

We argue in favour of developing a comprehensive dynamical theory for rationalizing, predicting, designing, and machine learning nonequilibrium phenomena that occur in soft matter. To give guidance for navigating the theoretical and practical challenges that lie ahead, we discuss and exemplify the limitations of dynamical density functional theory (DDFT). Instead of the implied adiabatic sequence of equilibrium states that this approach provides as a makeshift for the true time evolution, we posit that the pending theoretical tasks lie in developing a systematic understanding of the dynamical functional relationships that govern the genuine nonequilibrium physics. While static density functional theory gives a comprehensive account of the equilibrium properties of many-body systems, we argue that power functional theory is the only present contender to shed similar insights into nonequilibrium dynamics, including the recognition and implementation of exact sum rules that result from the Noether theorem. As a demonstration of the power functional point of view, we consider an idealized steady sedimentation flow of the three-dimensional Lennard-Jones fluid and machine-learn the kinematic map from the mean motion to the internal force field. The trained model is capable of both predicting and designing the steady state dynamics universally for various target density modulations. This demonstrates the significant potential of using such techniques in nonequilibrium many-body physics and overcomes both the conceptual constraints of DDFT as well as the limited availability of its analytical functional approximations.

Comparative study of force-based classical density functional theory.

We reexamine results obtained with the recently proposed density functional theory framework based on forces (force-DFT) [S. M. Tschopp et al., Phys. Rev. E 106, 014115 (2022)2470-004510.1103/PhysRevE.106.014115]. We compare inhomogeneous density profiles for hard sphere fluids to results from both standard density functional theory and from computer simulations. Test situations include the equilibrium hard sphere fluid adsorbed against a planar hard wall and the dynamical relaxation of hard spheres in a switched harmonic potential. The comparison to grand canonical Monte Carlo simulation profiles shows that equilibrium force-DFT alone does not improve upon results obtained with the standard Rosenfeld functional. Similar behavior holds for the relaxation dynamics, where we use our event-driven Brownian dynamics data as benchmark. Based on an appropriate linear combination of standard and force-DFT results, we investigate a simple hybrid scheme which rectifies these deficiencies in both the equilibrium and the dynamical case. We explicitly demonstrate that although the hybrid method is based on the original Rosenfeld fundamental measure functional, its performance is comparable to that of the more advanced White Bear theory.

Clinician perspectives on pediatric COVID-19 vaccination: A qualitative study in central and western, Massachusetts.

We explored perspectives of clinicians in central and western Massachusetts about efforts to vaccinate pediatric patients against COVID-19 as well as best practices and challenges for vaccine delivery. We conducted semi-structured qualitative interviews (n = 16) with family practice and pediatric clinicians between late October and early December 2021. Our interviews addressed: process for vaccination and vaccine promotion, parental receptivity to COVID-19 vaccination, receptivity to other pediatric vaccines, resources needed to support vaccine promotion, and best practices developed to encourage hesitant parents. Using a multi-prong recruitment strategy we invited clinicians to participate in telephone interviews, which were audio-recorded and transcribed. We used rapid qualitative analysis to produce summary templates for each interview which were ultimately combined into a matrix summary. The majority of participants (n = 10) were offering the vaccine in their own clinics, while the remainder cited challenges related to staffing, logistics, and space that prevented them from offering the vaccine. Clinicians reported parents fall into three groups: vaccine-accepting, hesitant but potentially accepting, and refusers. Strategies they identified that worked to encourage hesitant parents were sharing personal vaccine stories, acknowledging parents' fears about the vaccine, and being persistent with the most hesitant parents. Yet resources are needed including educational materials and training in how to have these conversations. While challenges related to staffing and space will be difficult to overcome for clinics to be able to offer vaccination on-site, our results highlight the importance of developing effective messaging strategies and training clinicians in how to integrate them into routine practice.

Force density functional theory in- and out-of-equilibrium.

When a fluid is subject to an external field, as is the case near an interface or under spatial confinement, then the density becomes spatially inhomogeneous. Although the one-body density provides much useful information, a higher level of resolution is provided by the two-body correlations. These give a statistical description of the internal microstructure of the fluid and enable calculation of the average interparticle force, which plays an essential role in determining both the equilibrium and dynamic properties of interacting fluids. We present a theoretical framework for the description of inhomogeneous (classical) many-body systems, based explicitly on the two-body correlation functions. By consideration of local Noether-invariance against spatial distortion of the system we demonstrate the fundamental status of the Yvon-Born-Green (YBG) equation as a local force-balance within the fluid. Using the inhomogeneous Ornstein-Zernike equation we show that the two-body correlations are density functionals and, thus, that the average interparticle force entering the YBG equation is also a functional of the one-body density. The force-based theory we develop provides an alternative to standard density functional theory for the study of inhomogeneous systems both in- and out-of-equilibrium. We compare force-based density profiles to the results of the standard potential-based (dynamical) density functional theory. In-equilibrium, we confirm both analytically and numerically that the standard approach yields profiles that are consistent with the compressibility pressure, whereas the force-density functional gives profiles consistent with the virial pressure. For both approaches we explicitly prove the hard-wall contact theorem that connects the value of the density profile at the hard-wall with the bulk pressure. The structure of the theory offers deep insights into the nature of correlation in dense and inhomogeneous systems.

Biocontrol of Plant Diseases Using Glycyrrhiza glabra Leaf Extract.

The growing concern regarding the potential risks of pesticides and their impact on nontarget organisms stimulates the development and application of alternative, environmentally friendly products. It seems necessary to develop alternatives for conventional products and for those already widely used in organic agriculture, e.g., copper. Very importantly, such alternative products should not limit the productivity and profitability of agriculture. In this study, we examined the efficacy of licorice (Glycyrrhiza glabra) leaf extract as such an alternative. We tested its impact on the virulence of Pseudomonas syringae toward the model plant Arabidopsis thaliana and the crop plant tomato (Solanum lycopersicum) as well as of Clavibacter michiganensis, Xanthomonas campestris, and Phytophthora infestans toward tomato, at multiple levels. We demonstrate that licorice leaf extract acts as a direct fungicide and bactericide. Moreover, it acts against a metalaxyl-resistant P. infestans strain. In addition, the extract from licorice leaves influences the plant immune system, modulating the plant responses to the challenge with pathogen(s); this involves both salicylic acid and ethylene-based responses. Our results show that in addition to the well-known use of licorice root extract in medicine, the leaf extract can be an effective alternative in organic and integrated farming, contributing to copper reduction and resistance management.[Formula: see text] Copyright © 2022 The Author(s). This is an open-access article distributed under the CC BY 4.0 International license.

Why Noether's theorem applies to statistical mechanics.

Noether's theorem is familiar to most physicists due its fundamental role in linking the existence of conservation laws to the underlying symmetries of a physical system. Typically the systems are described in the particle-based context of classical mechanics or on the basis of field theory. We have recently shown (2021Commun. Phys.4176) that Noether's reasoning also applies to thermal systems, where fluctuations are paramount and one aims for a statistical mechanical description. Here we give a pedagogical introduction based on the canonical ensemble and apply it explicitly to ideal sedimentation. The relevant mathematical objects, such as the free energy, are viewed as functionals. This vantage point allows for systematic functional differentiation and the resulting identities express properties of both macroscopic average forces and molecularly resolved correlations in many-body systems, both in and out-of-equilibrium, and for active Brownian particles. To provide further background, we briefly describe the variational principles of classical density functional theory, of power functional theory, and of classical mechanics.

Factors in the Use of Workplace Health Promotion on Back Health. Results of the Survey "German Health Update".

Background: The influence of the working environment on the back health of employees is well-documented. Many companies have begun to offer employees access to services to promote back health. Factors affecting the use of these offers at the population level have received little investigation to date. The current study examined the socio-demographic factors, physical activity and health-related factors, and work-related factors associated with the use of offers of workplace health promotion for back health in Germany. Materials and Methods: In the representative population-based cross-sectional survey "German Health Update" (GEDA 2014/2015-EHIS) conducted by the Robert Koch Institute, 12,072 employees aged 18-64 years old were surveyed from November 2014 to July 2015 regarding the use of back health services in their companies. In addition to socio-demographic factors, the survey examined working hours, physical activity in leisure time, health awareness, and subjective complaints in the lower back or other chronic back problems in the last 12 months. The interaction of these factors with the utilization of back health services was tested using multiple logistic regression models. Results: Women used back health services more often than men (women: 25.5%; men: 18.1%). Female gender was associated with part-time employment (OR 0.72) and a strong to very strong level of health awareness (OR 1.40). Male gender was associated with age between 30 and 44 years (OR 1.99) and 45-64 years (OR 2.02), low socioeconomic status (OR 0.48), endurance activity of <2.5 h per week (OR 0.62), and absence of lower back pain or other chronic back conditions for the last 12 months (OR 0.48). Conclusion: The present study is the first to provide findings regarding the factors associated with the utilization of workplace health promotion to promote back health at the population level, and from the perspective of employees in Germany. The results revealed that the relevant factors for participating in offers differ for women and men. To reach more employees, workplace health promotion offers for back health should be designed specifically for each individual, considering gender and age, working hours, health awareness and behavior, and health state.

[The use of workplace health promotion interventions in Germany-results of the study "German Health Update" (GEDA 2014/2015-EHIS)]. / Inanspruchnahme von Maßnahmen der betrieblichen Gesundheitsförderung in Deutschland ­ Ergebnisse der Studie "Gesundheit in Deutschland aktuell" (GEDA 2014/2015-EHIS).

BACKGROUND/OBJECTIVES: Workplace health promotion (WHP) interventions can reach a large part of the population. They are designed to improve work organisation and conditions and to promote the personal competencies of employees. Here the aim was to describe the use of WHP interventions based on individual factors and factors related to the size and branch of the companies. MATERIALS AND METHODS: In the representative population-based study "German Health Update" (GEDA 2014/15-EHIS) conducted by the Robert Koch Institute, 14,389 employees aged between 18 and 64 years were asked about their knowledge and use of workplace measures in their companies during the last 12 months regarding back health, stress management/relaxation and a canteen with healthy food. In addition to socio-demographic factors, health awareness and self-rated health on the use of WHP interventions was analysed. RESULTS: A canteen with healthy food is used by 64.6% of women (F) and 66.2% of men (M); offers for back health (F: 26.2%; M: 18.7%) and stress/relaxation (F: 35.2%; M: 25.6%) are used significantly less. Employees with more pronounced health awareness use the offers more frequently than employees with a less pronounced awareness of health. Men with poor self-rated health make more use of offers for back health and stress/relaxation than men with good self-rated health. CONCLUSIONS: In order to reach a larger part of the working population, WHP measures should take the needs of specific target groups into account including sex/gender and age aspects as well as the extent of employment, health awareness and self-rated health status.

Regulation of Cell Type-Specific Immunity Networks in Arabidopsis Roots.

While root diseases are among the most devastating stresses in global crop production, our understanding of root immunity is still limited relative to our knowledge of immune responses in leaves. Considering that root performance is based on the concerted functions of its different cell types, we undertook a cell type-specific transcriptome analysis to identify gene networks activated in epidermis, cortex, and pericycle cells of Arabidopsis (Arabidopsis thaliana) roots challenged with two immunity elicitors, the bacterial flagellin-derived flg22 and the endogenous Pep1 peptide. Our analyses revealed distinct immunity gene networks in each cell type. To further substantiate our understanding of regulatory patterns underlying these cell type-specific immunity networks, we developed a tool to analyze paired transcription factor binding motifs in the promoters of cell type-specific genes. Our study points toward a connection between cell identity and cell type-specific immunity networks that might guide cell types in launching immune response according to the functional capabilities of each cell type.

Utilisation of canteens offering healthy food choices as part of workplace health promotion in Germany.

Ensuring that canteens offer employees healthy food choices is a settings-based measure of work-place health promotion. The German Health Update (GEDA 2014/2015-EHIS) surveyed the knowledge and use of canteens with healthy food choices by 18- to 64-year-old female and male employees. Over the previous twelve months, 64.6% of women and 66.2% of men had, where available, eaten at canteens with healthy food options at their place of work. These figures on canteen use decline with age. The most frequent use is by employees in the high education group. Women working full-time eat in canteens offering healthy food choices more often than women working part-time. No difference in relation to the number of hours worked is observed for men. Healthy food choices in canteens should continue to be promoted.

Phase coexistence of active Brownian particles.

We investigate motility-induced phase separation of active Brownian particles, which are modeled as purely repulsive spheres that move due to a constant swim force with freely diffusing orientation. We develop on the basis of power functional concepts an analytical theory for nonequilibrium phase coexistence and interfacial structure. Theoretical predictions are validated against Brownian dynamics computer simulations. We show that the internal one-body force field has four nonequilibrium contributions: (i) isotropic drag and (ii) interfacial drag forces against the forward motion, (iii) a superadiabatic spherical pressure gradient, and (iv) the quiet life gradient force. The intrinsic spherical pressure is balanced by the swim pressure, which arises from the polarization of the free interface. The quiet life force opposes the adiabatic force, which is due to the inhomogeneous density distribution. The balance of quiet life and adiabatic forces determines bulk coexistence via equality of two bulk state functions, which are independent of interfacial contributions. The internal force fields are kinematic functionals which depend on density and current but are independent of external and swim forces, consistent with power functional theory. The phase transition originates from nonequilibrium repulsion, with the agile gas being more repulsive than the quiet liquid.

Non-negative Interfacial Tension in Phase-Separated Active Brownian Particles.

We present a microscopic theory for the nonequilibrium interfacial tension γ_{gl} of the free interface between gas and liquid phases of active Brownian particles. The underlying square gradient treatment and the splitting of the force balance in flow and structural contributions is general and applies to inhomogeneous nonequilibrium steady states. We find γ_{gl}≥0, which opposes claims by Bialké et al. [Phys. Rev. Lett. 115, 098301 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.098301] and delivers the theoretical justification for the widely observed interfacial stability in active Brownian dynamics many-body simulations.

Active ideal sedimentation: exact two-dimensional steady states.

We consider an ideal gas of active Brownian particles that undergo self-propelled motion and both translational and rotational diffusion under the influence of gravity. We solve analytically the corresponding Smoluchowski equation in two space dimensions for steady states. The resulting one-body density is given as a series, where each term is a product of an orientation-dependent Mathieu function and a height-dependent exponential. A lower hard wall is implemented as a no-flux boundary condition. Numerical evaluation of the suitably truncated analytical solution shows the formation of two different spatial regimes upon increasing Peclet number. These regimes differ in their mean particle orientation and in their variation of the orientation-averaged density with height.