An efficient multiscale method for subwavelength transient analysis of acoustic metamaterials.

A reduced-order homogenization framework is proposed, providing a macro-scale-enriched continuum model for locally resonant acoustic metamaterials operating in the subwavelength regime, for both time and frequency domain analyses. The homogenized continuum has a non-standard constitutive model, capturing a metamaterial behaviour such as negative effective bulk modulus, negative effective density and Willis coupling. A suitable reduced space is constructed based on the unit cell response in a steady-state regime and the local resonance regime. A frequency domain numerical example demonstrates the efficiency and suitability of the proposed framework.This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 2)'.

Modeling biological growth of human keratoconus: On the effect of tissue degradation, location and size.

Keratoconus is a non-inflammatory bilateral disease, that usually occurs in the inferior-temporal region, where the cornea bulges out and becomes thinner, due to the gradual loss of structural organization in corneal tissue. Degenerated extracellular matrix and fibers breakage have been observed in keratoconic corneas, that may promote the progression of the pathology. While keratoconus histopathology has been widely described in literature, its etiology is still not clear. Being able to fully understand keratoconus growing process could be crucial to detect its development and improve prevention strategies. This work proposes a novel continuum-based keratoconus growth model. The proposed framework accounts for the structural changes occurring in the underlying tissue during the progression of the disease, as indicated in experiments. The developed formulation is able to replicate the typical bulging and thinning of keratoconic corneas, as well as different forms in terms of shape, as they are commonly classified in clinics (nipple, oval and globus cones). The cone that is obtained constitutes a permanent deformed state, not pressure dependent. The resulting model may help to better understand the etiology of the behavior of this disease with the aim of improving the diagnosis and the treatment of the pathology.

Pre-Failure Strain Localization in Siliclastic Rocks: A Comparative Study of Laboratory and Numerical Approaches.

We combined novel laboratory techniques and numerical modeling to investigate (a)seismic preparatory processes associated with deformation localization during a triaxial failure test on a dry sample of Berea sandstone. Laboratory observations were quantified by measuring strain localization on the sample surface with a distributed strain sensing (DSS) array, utilizing optical fibers, in conjunction with both passive and active acoustic emission (AE) techniques. A physics-based computational model was subsequently employed to understand the underlying physics of these observations and to establish a spatio-temporal correlation between the laboratory and modeling results. These simulations revealed three distinct stages of preparatory processes: (i) highly dissipative fronts propagated towards the middle of the sample correlating with the observed acoustic emission locations; (ii) dissipative regions were individuated in the middle of the sample and could be linked to a discernible decrease of the P-wave velocities; (iii) a system of conjugate bands formed, coalesced into a single band that grew from the center towards the sample surface and was interpreted to be representative for the preparation of a weak plane. Dilatative lobes at the process zones of the weak plane extended outwards and grew to the surface, causing strain localization and an acceleration of the simulated deformation prior to failure. This was also observed during the experiment with the strain rate measurements and spatio-temporally correlated with an increase of the seismicity rate in a similar rock volume. The combined approach of such laboratory and numerical techniques provides an enriched view of (a)seismic preparatory processes preceding the mainshock.

All-Optical Control of Vortex Lasing in Silicon-Organic Lattices.

This paper reports a silicon-organic hybrid lattice that can lase with vortex emission and allow all-optical control. We combine an array of amorphous silicon nanodisks with gain from dye molecules in organic solvents to generate vortex lasing from bound states in the continuum under pulsed optical pumping. Irradiating the device with an additional continuous wave green laser beam can cause optical heating in silicon and lead to negative change in the refractive index of the organic solvents; meanwhile, the green laser beam can provide additional gain. Dynamic tuning of the lasing wavelength is achieved by varying the intensity of the controlling beam. Furthermore, the vortex beam lasing can be switched to single-lobed beam lasing by moving the controlling spot to break the in-plane symmetry within the pumping spot. Our findings could shed new light on active silicon topological devices.

Are psychotic-like experiences associated with aberrant prosocial decision-making behavior?

Introduction: Deficits in social functioning and decision-making are well-documented in schizophrenia, but their relationship with positive symptoms and social conflicts is poorly understood. We created a new paradigm based on the Dictator Game (DG) to explore differences in social decision-making between individuals experiencing high levels of psychotic-like experiences (PLEs), particularly hallucinations and delusions, and controls with less PLEs. Methods: A large community sample (N = 1,161) completed a DG in an online study whereby extreme groups were built based on the positive subscale of the CAPE. Results: Overall, participants experiencing PLEs did not act less prosocial than controls but showed a somewhat aberrant decision-making behavior, particularly a pattern of behaving more prosocial in fair situations and generally favoring punishment over compensation relative to controls. Mediation analyses suggest that measures of empathy and Machiavellism have predictive power for prosocial behavior beyond group status. Discussion: The present study raises the possibility that individuals with high levels of PLEs may be less able to adapt their behavior to the situation at hand than controls. These irregularities might be due to deficits in social cognition which may elicit conflict, thus compromising social functioning and possibly contributing to the formation of positive symptoms.

Prokaryote communities along a source-to-estuary river continuum in the Brazilian Atlantic Forest.

The activities of microbiomes in river sediments play an important role in sustaining ecosystem functions by driving many biogeochemical cycles. However, river ecosystems are frequently affected by anthropogenic activities, which may lead to microbial biodiversity loss and/or changes in ecosystem functions and related services. While parts of the Atlantic Forest biome stretching along much of the eastern coast of South America are protected by governmental conservation efforts, an estimated 89% of these areas in Brazil are under threat. This adds urgency to the characterization of prokaryotic communities in this vast and highly diverse biome. Here, we present prokaryotic sediment communities in the tropical Juliana River system at three sites, an upstream site near the river source in the mountains (Source) to a site in the middle reaches (Valley) and an estuarine site near the urban center of Ituberá (Mangrove). The diversity and composition of the communities were compared at these sites, along with environmental conditions, the former by using qualitative and quantitative analyses of 16S rRNA gene amplicons. While the communities included distinct populations at each site, a suite of core taxa accounted for the majority of the populations at all sites. Prokaryote diversity was highest in the sediments of the Mangrove site and lowest at the Valley site. The highest number of genera exclusive to a given site was found at the Source site, followed by the Mangrove site, which contained some archaeal genera not present at the freshwater sites. Copper (Cu) concentrations were related to differences in communities among sites, but none of the other environmental factors we determined was found to have a significant influence. This may be partly due to an urban imprint on the Mangrove site by providing organic carbon and nutrients via domestic effluents.

Slipping Through the Cracks: Clinicians' Perspectives on the Gaps in New York City's Public Mental Health System.

Most people who seek mental health treatment cannot access it. Certain groups (e.g., Medicaid enrollees and the uninsured) face particularly severe treatment access barriers along the care continuum. We interviewed 31 clinicians across two studies about their perspectives working in New York City's public mental health system. Because every clinician across both studies reported gaps in the system, we deployed an emergent, "serendipitous finding" approach and qualitatively analyzed the interviews together. Clinicians described three public mental health system gaps. First, many treatment-seekers must wait long periods of time to receive care and some never receive it at all. Second, patients with more serious challenges cannot access longer-term, higher-intensity, or specialized treatment. Third, some patients receiving high-intensity services may benefit from lower-intensity mental health support that is better integrated with medical and social service support. Coordinated and sustained financial investments at every step of the mental healthcare continuum are needed.

Flexible Terahertz Metasurface Absorbers Empowered by Bound States in the Continuum.

Terahertz absorbers are crucial to the cutting-edge techniques in the next-generation wireless communications, imaging, sensing, and radar stealth, as they fundamentally determine the performance of detectors and cloaking capabilities. It has long been a pressing task to find absorbers with customizable performance that can adapt to various environments with low cost and great flexibility. Here, perfect absorption empowered by bound states in the continuum (BICs) is demonstrated, allowing for the tailoring of absorption coefficient, bandwidth, and field of view. The one-port absorbers are interpreted using temporal coupled-mode theory highlighting the dominant role of BICs in the far-field radiation properties. Through a thorough investigation of BICs from the perspective of lattice symmetry, the radiation features of three BIC modes are unraveled using both multipolar and topological analysis. The versatile radiation capabilities of BICs provide ample freedom to meet specific requirements of absorbers, including tunable bandwidth, stable performance in a large field of view, and multiband absorption using a thin and flexible film without extreme geometric demands. These findings offer a systematic approach to developing optoelectronic devices and demonstrate the significant potential of BICs for optical and photonic applications, which will stimulate further studies on terahertz photonics and metasurfaces.

The UT Health Living Room: Expanding the Psychiatric Crisis Continuum of Care.

Traditional forms of psychiatric crisis treatment increasingly are being buttressed by services along the Psychiatric Crisis Continuum of Care, such as short-term crisis stabilization services and peer crisis services. The UT Health Living Room (LR) is an outpatient crisis counseling service that adds three promising elements to the Continuum: (1) it integrates outpatient treatment plans into crisis counseling, (2) provides care in a space and with staff who are familiar to patients, and (3) provides training in evidence-based crisis intervention. We examined two-year LR feasibility and outcome data. Mixed-method analyses used longitudinal clinic data and patient self-report measures. Results provide initial support for the feasibility, cost effectiveness and clinical effectiveness of the LR. Limitations include non-blinded ratings, limited experimental control, and simple cost-effectiveness methodology. The UT Living Room is feasible and offers novel elements to help patients in community clinics address emotional crises.

Revealing Mode Formation in Quasi-Bound States in the Continuum Metasurfaces via Near-Field Optical Microscopy.

Photonic metasurfaces offer exceptional control over light at the nanoscale, facilitating applications spanning from biosensing, and nonlinear optics to photocatalysis. Many metasurfaces, especially resonant ones, rely on periodicity for the collective mode to form, which makes them subject to the influences of finite size effects, defects, and edge effects, which have considerable negative impact at the application level. These aspects are especially important for quasi-bound state in the continuum (BIC) metasurfaces, for which the collective mode is highly sensitive to perturbations due to high-quality factors and strong near-field enhancement. Here, the mode formation in quasi-BIC metasurfaces on the individual resonator level using scattering scanning near-field optical microscopy (s-SNOM) in combination with a new image processing technique, is quantitatively investigated. It is found that the quasi-BIC mode is formed at a minimum size of 10 × 10-unit cells much smaller than expected from far-field measurements. Furthermore, it is shown that the coupling direction of the resonators, defects and edge states have pronounced influence on the quasi-BIC mode. This study serves as a link between the far-field and near-field responses of metasurfaces, offering crucial insights for optimizing spatial footprint and active area, holding promise for augmenting applications such as catalysis and biospectroscopy.

Cellular basis of the legume-rhizobium symbiosis.

The legume-rhizobium symbiosis represents the most important system for terrestrial biological nitrogen fixation. During the legume-rhizobium symbiosis, efficient nitrogen fixation depends on successful rhizobia infection and complete endosymbiosis, which are achieved by complicated cellular events involving cell wall remodeling, cytoskeletal reorganizations, and extensive membrane expansion and trafficking. In this review, we depict dynamic remodeling of the plant-unique cell Wall-Membrane system-Cytoskeleton continuum during symbiotic nitrogen fixation, especially in rhizobia uptake, infection thread formation and elongation, rhizobia droplet release, cytoplasmic bridge formation, and rhizobia endosymbiosis for efficient nitrogen fixation. We finally discuss the advanced techniques for deeply exploring the cellular basis of root nodule symbiosis, and provide insights into the unsolved mysteries of robust symbiotic nitrogen fixation.

Automated Quantification of Periodic Discharges in Human Electroencephalogram.

Periodic discharges (PDs) are pathologic patterns of epileptiform discharges repeating at regular intervals, commonly detected in the human electroencephalogram (EEG) signals in patients who are critically ill. The frequency and spatial extent of PDs are associated with the tendency of PDs to cause brain injury, existing automated algorithms do not quantify the frequency and spatial extent of PDs. The present study presents an algorithm for quantifying frequency and spatial extent of PDs. The algorithm quantifies the evolution of these parameters within a short (10-14 second) window, with a focus on lateralized and generalized periodic discharges. We test our algorithm on 300 ``easy'', 300 ``medium'', and 240 ``hard'' examples (840 total epochs) of periodic discharges as quantified by interrater consensus from human experts when analyzing the given EEG epochs. We observe $95.0\%$ agreement with a 95\% confidence interval (CI) of $[94.9\%, 95.1\%]$ between algorithm outputs with reviewer clincal judgement for easy examples, $92.0\%$ agreement (95\% CI $[91.9\%, 92.2\%]$) for medium examples, and $90.4\%$ agreement (95\% CI $[90.3\%, 90.6\%]$) for hard examples. The algorithm is also computationally efficient and is able to run in $0.385 \pm 0.038$ seconds for a single epoch using our provided implementation of the algorithm. The results demonstrate the algorithm's effectiveness in quantifying these discharges and provide a standardized and efficient approach for PD quantification as compared to existing manual approaches.

Assessing the HIV care continuum among transgender women during 11 years of follow-up: results from the Netherlands' ATHENA observational cohort.

INTRODUCTION: Transgender women are at increased risk of acquiring HIV. Earlier studies reported lower retention in HIV care, antiretroviral therapy uptake, adherence and viral suppression. We assessed the stages of the HIV care continuum of transgender women in the Netherlands over an 11-year period. In addition, we assessed new HIV diagnoses and late presentation, as well as disengagement from care, between 2011 and 2021. METHODS: Using data from the Dutch national ATHENA cohort, we separately assessed viral suppression, as well as time to achieving viral suppression, among transgender women for each year between 2011 and 2021. We also assessed trends in new HIV diagnoses and late presentation (CD4 count of <350 cells/µl and/or AIDS at diagnosis), and disengagement from care. RESULTS: Between 2011 and 2021, a total of 260 transgender women attended at least one HIV clinical visit. Across all years, <90% of transgender women were virally suppressed (207/239 [87%] in 2021). The number of new HIV diagnoses fluctuated for transgender women (ptrend = 0.053) and late presentation was common (ranging between 10% and 67% of new HIV diagnoses). Of the 260 transgender women, 26 (10%) disengaged from care between 2011 and 2021 (incidence rate = 1.10 per 100 person-years, 95% confidence interval = 0.75-1.61). CONCLUSIONS: Between 2011 and 2021, less than 90% of transgender women linked to HIV care were virally suppressed. Late presentation at the time of diagnosis and disengagement from care were common. Efforts are needed to identify barriers to early HIV diagnosis and to optimize the different steps across the care continuum for transgender women.

Sex and population differences in the cardiometabolic continuum: a machine learning study using the UK Biobank and ELSA-Brasil cohorts.

BACKGROUND: The temporal relationships across cardiometabolic diseases (CMDs) were recently conceptualized as the cardiometabolic continuum (CMC), sequence of cardiovascular events that stem from gene-environmental interactions, unhealthy lifestyle influences, and metabolic diseases such as diabetes, and hypertension. While the physiological pathways linking metabolic and cardiovascular diseases have been investigated, the study of the sex and population differences in the CMC have still not been described. METHODS: We present a machine learning approach to model the CMC and investigate sex and population differences in two distinct cohorts: the UK Biobank (17,700 participants) and the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) (7162 participants). We consider the following CMDs: hypertension (Hyp), diabetes (DM), heart diseases (HD: angina, myocardial infarction, or heart failure), and stroke (STK). For the identification of the CMC patterns, individual trajectories with the time of disease occurrence were clustered using k-means. Based on clinical, sociodemographic, and lifestyle characteristics, we built multiclass random forest classifiers and used the SHAP methodology to evaluate feature importance. RESULTS: Five CMC patterns were identified across both sexes and cohorts: EarlyHyp, FirstDM, FirstHD, Healthy, and LateHyp, named according to prevalence and disease occurrence time that depicted around 95%, 78%, 75%, 88% and 99% of individuals, respectively. Within the UK Biobank, more women were classified in the Healthy cluster and more men in all others. In the EarlyHyp and LateHyp clusters, isolated hypertension occurred earlier among women. Smoking habits and education had high importance and clear directionality for both sexes. For ELSA-Brasil, more men were classified in the Healthy cluster and more women in the FirstDM. The diabetes occurrence time when followed by hypertension was lower among women. Education and ethnicity had high importance and clear directionality for women, while for men these features were smoking, alcohol, and coffee consumption. CONCLUSIONS: There are clear sex differences in the CMC that varied across the UK and Brazilian cohorts. In particular, disadvantages regarding incidence and the time to onset of diseases were more pronounced in Brazil, against woman. The results show the need to strengthen public health policies to prevent and control the time course of CMD, with an emphasis on women.

On the generation of force required for actin-based motility.

The fundamental question of how forces are generated in a motile cell, a lamellipodium, and a comet tail is the subject of this note. It is now well established that cellular motility results from the polymerization of actin, the most abundant protein in eukaryotic cells, into an interconnected set of filaments. We portray this process in a continuum mechanics framework, claiming that polymerization promotes a mechanical swelling in a narrow zone around the nucleation loci, which ultimately results in cellular or bacterial motility. To this aim, a new paradigm in continuum multi-physics has been designed, departing from the well-known theory of Larché-Cahn chemo-transport-mechanics. In this note, we set up the theory of network growth and compare the outcomes of numerical simulations with experimental evidence.

Modeling free tumor growth: Discrete, continuum, and hybrid approaches to interpreting cancer development.

Tumor growth dynamics serve as a critical aspect of understanding cancer progression and treatment response to mitigate one of the most pressing challenges in healthcare. The in silico approach to understanding tumor behavior computationally provides an efficient, cost-effective alternative to wet-lab examinations and are adaptable to different environmental conditions, time scales, and unique patient parameters. As a result, this paper explored modeling of free tumor growth in cancer, surveying contemporary literature on continuum, discrete, and hybrid approaches. Factors like predictive power and high-resolution simulation competed against drawbacks like simulation load and parameter feasibility in these models. Understanding tumor behavior in different scenarios and contexts became the first step in advancing cancer research and revolutionizing clinical outcomes.

Microsporidian coinfection reduces fitness of a fungal pathogen due to rapid host mortality.

Infection outcomes can be strongly context dependent, shifting a host-symbiont relationship along a parasitism-mutualism continuum. Numerous studies show that under stressful conditions, symbionts that are typically mutualistic can become parasitic. The reverse possibility, a parasite becoming mutualistic, has received much less study. We investigated whether the parasitic microsporidium Ordospora pajunii can become beneficial for its host Daphnia dentifera in the presence of the more virulent fungal pathogen Metschnikowia bicuspidata. We found that, even though infection with O. pajunii reduces the frequency of penetration of M. bicuspidata spores into the host body cavity, it does not improve the survival or reproduction of the host; conversely, coinfection increased the mortality of Daphnia. This shorter lifespan of coinfected hosts disrupted the life cycle of M. bicuspidata, greatly reducing its fitness. Thus, coinfection with both pathogens was detrimental to the host at the individual level but might be beneficial for the host population as a result of greatly reduced production of M. bicuspidata spores. If so, this would mean that O. pajunii outbreaks should delay or prevent M. bicuspidata outbreaks. In support of this, in an analysis of dynamics of naturally occurring outbreaks in two lakes where these pathogens co-occur, we found a time lag in occurrence between O. pajunii and M. bicuspidata, with M. bicuspidata epidemics only occurring after the collapse of O. pajunii epidemics. Thus, these results suggest that the interaction between co-occurring symbionts, and the net impact of a symbiont on a host, might be qualitatively different at different scales.IMPORTANCEUnderstanding the factors that modify infection probability and virulence is crucial for identifying the drivers of infection outbreaks and modeling disease epidemic progression, and increases our ability to control diseases and reduce the harm they cause. One factor that can strongly influence infection probability and virulence is the presence of other pathogens. However, while coexposures and coinfections are incredibly common, we still have only a limited understanding of how pathogen interactions alter infection outcomes or whether their impacts are scale dependent. We used a system of one host and two pathogens to show that sequential coinfection can have a tremendous impact on the host and the infecting pathogens and that the outcome of (co-)infection can be negative or positive depending on the focal organization level.

Improved accuracy of continuum surface flux models for metal additive manufacturing melt pool simulations.

Computational modeling of the melt pool dynamics in laser-based powder bed fusion metal additive manufacturing (PBF-LB/M) promises to shed light on fundamental mechanisms of defect generation. These processes are accompanied by rapid evaporation so that the evaporation-induced recoil pressure and cooling arise as major driving forces for fluid dynamics and temperature evolution. The magnitude of these interface fluxes depends exponentially on the melt pool surface temperature, which, therefore, has to be predicted with high accuracy. The present work utilizes a diffuse interface finite element model based on a continuum surface flux (CSF) description of interface fluxes to study dimensionally reduced thermal two-phase problems representative for PBF-LB/M in a finite element framework. It is demonstrated that the extreme temperature gradients combined with the high ratios of material properties between metal and ambient gas lead to significant errors in the interface temperatures and fluxes when classical CSF approaches, along with typical interface thicknesses and discretizations, are applied. It is expected that this finding is also relevant for other types of diffuse interface PBF-LB/M melt pool models. A novel parameter-scaled CSF approach is proposed, which is constructed to yield a smoother temperature field in the diffuse interface region, significantly increasing the solution accuracy. The interface thickness required to predict the temperature field with a given level of accuracy is less restrictive by at least one order of magnitude for the proposed parameter-scaled approach compared to classical CSF, drastically reducing computational costs. Finally, we showcase the general applicability of the parameter-scaled CSF to a 3D simulation of stationary laser melting of PBF-LB/M considering the fully coupled thermo-hydrodynamic multi-phase problem, including phase change.

Dirac exciton-polariton condensates in photonic crystal gratings.

Bound states in the continuum have recently been utilized in photonic crystal gratings to achieve strong coupling and ultralow threshold condensation of exciton-polariton quasiparticles with atypical Dirac-like features in their dispersion relation. Here, we develop the single- and many-body theory of these new effective relativistic polaritonic modes and describe their mean-field condensation dynamics facilitated by the interplay between protection from the radiative continuum and negative-mass optical trapping. Our theory accounts for tunable grating parameters giving full control over the diffractive coupling properties between guided polaritons and the radiative continuum, unexplored for polariton condensates. In particular, we discover stable cyclical condensate solutions mimicking a driven-dissipative analog of the zitterbewegung effect characterized by coherent superposition of ballistic and trapped polariton waves. We clarify important distinctions between the polariton nearfield and farfield explaining recent experiments on the emission characteristics of these long lived nonlinear Dirac polaritons.