The Evolution of Selection Bias in the Recent Epidemiologic Literature-A Selective Overview.

Selection bias has long been central in methodological discussions across epidemiology and other fields. In epidemiology, the concept of selection bias has been continually evolving over time. In this issue of the Journal, Mathur and Shpitser (Am J Epidemiol. XXXX;XXX(XX):XXXX-XXXX) present simple graphical rules for using a Single World Intervention Graph (SWIG) to assess the presence of selection bias when estimating treatment effects in both the general population and a selected sample. Notably, the authors examine the setting in which the treatment affects selection, an issue not well-addressed in the existing literature on selection bias. To place the work by Mathur and Shpitser in context, we review the evolution of the concept of selection bias in epidemiology, with a primary focus on the developments in the last 20-30 years since the introduction of causal directed acyclic graphs (DAGs) to epidemiologic research.

Synergistic interaction between pay-it-forward incentives and recreational drug use on hepatitis B virus and hepatitis C virus testing among men who have sex with men in China.

OBJECTIVES: Pay-it-forward incentives effectively promote hepatitis B virus (HBV) and hepatitis C virus (HCV) testing among men who have sex with men (MSM) by offering free testing and donation opportunities. This study aims to explore the interaction between pay-it-forward incentives and recreational drug use on HBV and HCV testing uptake among Chinese MSM. METHODS: We pooled data from two pay-it-forward studies that aimed to promote dual HBV and HCV testing among MSM in Jiangsu, China. We explored factors associated with hepatitis testing uptake in the two study groups and examined the interaction between pay-it-forward incentives and recreational drug use on hepatitis testing uptake. RESULTS: Overall, 511 MSM participated in these two studies, with 265 participants in the pay-it-forward incentives group and 246 participants in the standard-of-care group. Among these participants, 59.3% in the pay-it-forward incentive group and 24.8% in the standard-of-care group received dual HBV and HCV testing, respectively. In the pay-it-forward incentives group, participants who used recreational drugs in the past 12 months (adjusted OR (AOR)=1.83, 95% CI 1.09 to 3.06) were more likely to receive dual HBV and HCV testing, compared with those who never used recreational drugs, whereas in the standard-of-care group, those who used recreational drugs were less likely to receive dual HBC and HCV testing (AOR=0.38, 95% CI 0.18 to 0.78). MSM with higher community connectedness (AOR=1.10, 95% CI 1.00 to 1.21) were also more likely to receive hepatitis testing with pay-it-forward incentives. There was a synergistic interaction on both the multiplicative (ratio of ORs=4.83, 95% CI 1.98 to 11.7) and additive scales (the relative excess risk of interaction=2.97, 95% CI 0.56 to 5.38) of pay-it-forward incentives and recreational drug use behaviours on dual HBV and HCV testing uptake among MSM. CONCLUSION: Pay-it-forward incentives may be particularly useful in promoting hepatitis testing among MSM who use recreational drugs.

Reconstruction and analysis of transient evolution images of laser-produced plasma plumes.

We introduce a method for the analysis and simulation of transient images of laser-produced plasma (LPP) plumes. This method comprises three steps: (i) calculating the two-dimensional distribution of plasma parameters using a radiation hydrodynamics model, (ii) constructing radiation paths through ray tracing, and (iii) solving the radiation transport equation along these paths. In our simulations, we have meticulously considered factors that could influence the imaging results, including the quantum efficiency to different radiation wavelengths, the imaging lens' transmittance, the target surface's reflectivity, and the absorption, emission, and scattering quantum effect of the detector processes occurring in the plasma. We applied this method to analyze and simulate the transient images of aluminum plasma plumes in a background air environment at a pressure of 2000 Pa. The results demonstrate that our method not only produces simulated images that align with experimental results but also provides a reliable distribution of plasma state parameters and clearly identifies the ion species radiating in different bands. Given its capability in transient image reconstruction and its adaptability as a tool for spectral simulation and analysis of LPPs, we believe this method holds significant potential for spectral diagnostics in fields such as laser-induced breakdown spectroscopy, extreme ultraviolet lithography sources, and high-energy-density physics, among others.

The Influence of Perinatal Psychological Changes on Infant Neurodevelopment in Shanghai, China: A Longitudinal Group-based Trajectory Analysis.

OBJECTIVE: This prospective cohort study, conducted at the Fenglin Community Health Service Center (FCHC) in Xuhui District, Shanghai, aimed to investigate the impact of maternal psychological status on offspring neurodevelopment. METHODS: A total of 430 mother-child pairs were included, with pregnant women enrolled between February 18, 2020, and April 19, 2021. Face-to-face interviews and electronic data collection on demographic characteristics, health conditions and medical history were employed at various stages of pregnancy and postpartum. Maternal depression and anxiety were assessed using the PHQ-9 and GAD-7 scales, while offspring neurodevelopment was measured at six months using the Ages and Stages Questionnaire 3rd Edition (ASQ-3). In statistical analyses, group-based trajectory modeling (GBTM) was employed to identify the latent groups for maternal psychological trajectories, including depression and anxiety, and logistic regression was used to explore associations between maternal psychological trajectories and offspring neurodevelopment, adjusting for potential confounders. RESULTS: Five latent trajectory groups were identified for both depression and anxiety, exhibiting distinct patterns over time. Results indicated that maternal psychological trajectories were associated with various domains of offspring neurodevelopment, including communication, problem-solving, personal-social, and gross motor skills. Specifically, mothers in trajectory groups characterized by the highest level of depression or anxiety showed increased odds of offspring neurodevelopmental delays compared to reference groups. CONCLUSION: Our findings underscore the importance of maternal mental health during the perinatal period and highlight the potential implications for offspring neurodevelopment. Further research is warranted to elucidate underlying mechanisms and inform targeted interventions to support maternal mental well-being and optimize offspring outcomes.

Kinetics of N- to M-Polar Switching in Ferroelectric Al1-xScxN Capacitors.

Ferroelectric wurtzite-type aluminum scandium nitride (Al1-xScxN) presents unique properties that can enhance the performance of non-volatile memory technologies. The realization of the full potential of Al1-xScxN requires a comprehensive understanding of the mechanism of polarization reversal and domain structure dynamics involved in the ferroelectric switching process. In this work, transient current integration measurements performed by a pulse switching method are combined with domain imaging by piezoresponse force microscopy (PFM) to investigate the kinetics of domain nucleation and wall motion during polarization reversal in Al0.85Sc0.15N capacitors. In the studied electric field range (from 4.4 to 5.6 MV cm-1), ferroelectric switching proceeds via domain nucleation and wall movement. The currently available phenomenological models are shown to not fully capture all the details of the complex dynamics of polarization reversal in Al0.85Sc0.15N. PFM reveals a non-linear increase of both domain nucleation rate and lateral wall velocity during the switching process, as well as the dependency of the domain pattern on the polarization reversal direction. A continuously faster N- to M-polar switching upon cycling is reported and ascribed to an increasing number of M-polar nucleation sites and density of domain walls.

Effects of root-zone warming, nitrogen supply and their interactions on root-shoot growth, nitrogen uptake and photosynthetic physiological characteristics of maize.

In the context of climate change, the impact of root-zone warming (RW) on crop nutrient absorption and utilization has emerged as a significant concern that cannot be overlooked. Nitrogen (N) is an essential element for crop growth and development, particularly under stress. The comprehensive effect and relationship between RW and N level remains unclear. The objective of this experiment was to investigate the impact of RW on root-shoot growth and photosynthetic physiological characteristics of maize seedlings under varying N levels. The results demonstrated that optimal RW was beneficial to the growth of maize, while excessive root-zone temperature (RT) significantly impeded N uptake in maize. Under low N treatment, the proportion of N distribution in roots increased, and the root surface area increased by 41 %. Furthermore, under low N levels, the decline in root vitality and the increase in root MDA caused by high RT were mitigated, resulting in an enhancement of the root's ability to cope with stress. For the above-ground part, under the double stress of high RT and low N, the shoot N concentration, leaf nitrate reductase, leaf glutamine synthase, chlorophyll content, net photosynthetic rate and shoot dry matter accumulation decreased by 86 %, 60 %, 35 %, 53 %, 64 % and 59 %, respectively. It can be reasonably concluded that reasonable N management is an important method to effectively reduce the impact of high RT stress.

Accessibility of Opioid Treatment Programs Based on Conventional vs Perceived Travel Time Measures.

Importance: Transportation barriers have long been associated with poorer health outcomes; this burden is especially acute for individuals with opioid use disorder (OUD), a chronic disease often associated with low socioeconomic status. Conventional travel time analyses may not fully account for experiential components of travel, thereby understating the true travel burden and overstating treatment accessibility to opioid treatment programs (OTPs). Objective: To develop a metric of feels-like accessibility for those using public transit to access OTPs that accounts for the realistic travel burden on individuals with OUD. Design, Setting, and Participants: This cross-sectional study integrated high-resolution transit schedules and operating hours of OTPs to measure feels-like accessibility. Feels-like accessibility considers the differential outcomes of out-of-vehicle travel components and more realistically reflects individuals' transportation burden than conventional accessibility measures. Gini indices and spatial regression models were used to investigate inequities in accessibility. Geocoded data for residential addresses of 1018 overdose fatalities in Connecticut in 2019 were used as a proxy for the treatment needs of individuals with OUD. Data were analyzed between May and August 2023. Main Outcomes and Measures: Conventional and feels-like accessibility scores. Exposures: Fluctuations in public transit frequencies over the course of the day and the limited operating hours of the OTPs. Results: Of the 1018 individuals in the study, the mean (SD) age at death was 43.7 (12.6) years, 784 individuals (77%) were men, 111 (11%) were African American, and 889 (87%) were White, with other racial and ethnic categories including 18 individuals (2%). A total of 264 individuals in the sample (26%) could not access an OTP within 180 minutes. For those who could access these facilities, the average 1-way travel time was 45.6 minutes, with individuals spending approximately 70% of their trip duration on out-of-vehicle travel components. The conventional accessibility metric underestimates individuals' travel burden to OTPs as well as the inequity in accessibility compared with the feels-like accessibility metric. For example, the median (range) conventional accessibility score, defined as the number of OTPs within 120 minutes of transit travel time, was 5.0 (0.0-17.0); the median (range) feels-like accessibility score, defined as the number of OTPs within 120 minutes of transit travel time weighted to account for in- and out-of-vehicle segments, was 1.0 (0.0-10.0). There is a considerable temporal variation in travel time and accessibility depending on the departure times. Conclusions and Relevance: In this cross-sectional study of travel burdens, the calculated feels-like accessibility scores, which consider the differential outcomes of out-of-vehicle travel components (eg, walking and waiting), could better and more realistically reflect passengers' transportation burden. Policy recommendations derived from the conventional accessibility metric could be misleading, and decision-makers should use feels-like accessibility metrics that adequately capture individuals' travel burdens. In the context of access to OTPs, the findings from this study suggest that opening new OTP sites to address gaps in access due to distance to services or extending hours of operation at existing sites may ameliorate the travel burden for individuals.

Electrically induced cancellation and inversion of piezoelectricity in ferroelectric Hf0.5Zr0.5O2.

HfO2-based thin films hold huge promise for integrated devices as they show full compatibility with semiconductor technologies and robust ferroelectric properties at nanometer scale. While their polarization switching behavior has been widely investigated, their electromechanical response received much less attention so far. Here, we demonstrate that piezoelectricity in Hf0.5Zr0.5O2 ferroelectric capacitors is not an invariable property but, in fact, can be intrinsically changed by electrical field cycling. Hf0.5Zr0.5O2 capacitors subjected to ac cycling undergo a continuous transition from a positive effective piezoelectric coefficient d33 in the pristine state to a fully inverted negative d33 state, while, in parallel, the polarization monotonically increases. Not only can the sign of d33 be uniformly inverted in the whole capacitor volume, but also, with proper ac training, the net effective piezoresponse can be nullified while the polarization is kept fully switchable. Moreover, the local piezoresponse force microscopy signal also gradually goes through the zero value upon ac cycling. Density functional theory calculations suggest that the observed behavior is a result of a structural transformation from a weakly-developed polar orthorhombic phase towards a well-developed polar orthorhombic phase. The calculations also suggest the possible occurrence of a non-piezoelectric ferroelectric Hf0.5Zr0.5O2. Our experimental findings create an unprecedented potential for tuning the electromechanical functionality of ferroelectric HfO2-based devices.

Dimensional Scaling of Ferroelectric Properties of Hafnia-Zirconia Thin Films: Electrode Interface Effects.

Hafnia-based ferroelectric (FE) thin films are promising candidates for semiconductor memories. However, a fundamental challenge that persists is the lack of understanding regarding dimensional scaling, including thickness scaling and area scaling, of the functional properties and their heterogeneity in these films. In this work, excellent ferroelectricity and switching endurance are demonstrated in 4 nm-thick Hf0.5Zr0.5O2 (HZO) capacitors with molybdenum electrodes in capacitors as small as 65 nm × 45 nm in size. The HZO layer in these capacitors can be crystallized into the ferroelectric orthorhombic phase at the low temperature of 400 °C, making them compatible for back-end-of-line (BEOL) FE memories. With the benefits of thickness scaling, low operation voltage (1.2 V) is achieved with high endurance (>1010 cycles); however, a significant fatigue regime is noted. We observed that the bottom electrode, rather than the top electrode, plays a dominant role in the thickness scaling of HZO ferroelectric behavior. Furthermore, ultrahigh switched polarization (remanent polarization 2Pr ∼ 108 µC cm-2) is observed in some nanoscale devices. This study advances the understanding of dimensional scaling effects in HZO capacitors for high-performance FE memories.