Linear Mixed-effect Model Regression Research Articles

Victory-in-freedom: Ukraine’s democratic resilience in the face of war

The article offers a rare systematic analysis of political attitudes in societies experiencing massive military invasions using statistical analysis of two original surveys conducted by the Ukraine National Academy of Sciences Institute of Sociology — a panel survey tracking the same respondents in three waves (N = 329, November 2021, June-July 2022, and June 2023) and an additional larger survey (N = 869, June 2023). Despite devastating suffering, Ukrainians’ support for democracy as a political system and for freedom of speech have stayed remarkably resilient over this time period. Cross-sectional (multiple ordinary least squares regression) and longitudinal (linear mixed-effects model regression) tests, as well as supplementary focus group conversations in all of Ukraine’s macro-regions, show that this democratic resilience is grounded in the victory-in-freedom synergy — a widespread sense of shared sacrifice that drives determination to win the war and restore Ukraine’s territorial integrity. In particular, we found a clearer understanding of the importance of political freedoms and fighting for victory among individuals who experienced loss and trauma and a strong appreciation across Ukraine’s society that victory is vital to preserve democracy. Survey data also demonstrates that democracy support has become more intrinsic to Ukrainian national identity and that the initial surge of democracy support among Ukrainians in the face of Russia’s invasion has been more than a short-term rallying-round-the-flag. In combination, these factors explain the Ukrainians’ sustained, spirited resilience in the face Russia’s mass savage invasion over more than a two-year period. Moreover, support for democratic ideals doesn’t mean Ukrainians write a blank check of trust to their government. Longitudinal analysis indicates that as the war progressed, and hardship persisted respondents held their democratic institutions accountable. At the same time, the results of our study indicate that sustaining this resilience would require not only battlefield successes, but also accountable governance, countering Russia’s media impacts, and sustaining family incomes. Our findings contribute to the literature on war and democracy by showing the importance of considering both the external context (war duration and impacts and the aggressor state type) and the mobilization of national identity in the face of aggression.

Characterizing stratum corneum structure, barrier function, and chemical content of human skin with coherent Raman scattering imaging.

The most superficial layer of the epidermis, the stratum corneum, plays a crucial role in retaining hydration; if its structure or composition is compromised, dry skin may result as a consequence of poor water retention. Dry skin is typically treated with topical application of humectant agents that attract water into the skin. Corneometry, the industry standard for measuring skin hydration, works by assessing the bulk electrical properties of skin. However, this technique samples a large volume of tissue and thus does not resolve the biochemical changes that occur at the cellular level that may underlie mechanisms of dry skin. These limitations can be addressed using coherent Raman scattering (CRS) microscopy to probe the intrinsic vibrational modes of chemical groups such as lipids and water. In the present study, ex vivo human skin explants undergoing dehydration and humectant-induced rehydration were measured via CRS imaging and corneometry. Corneometry data and chemically specific images were obtained from the stratum corneum of each patient sample at each timepoint. The resulting data was statistically analyzed using linear mixed effect model regression analysis. The cellular imaging data revealed water loss in the stratum corneum during dehydration that was correlated with corneometer readings. Interestingly, the imaging data and corneometer readings show differences under the experimental rehydration conditions. The rehydration results suggest that hydration restored by the humectant agents may not be retained by the corneocytes in the ex vivo model system. Given the complementary nature of corneometry, a bulk assessment tool, and CRS microscopy, a modality with subcellular resolution implemented here in an en-face tissue imaging setup, these techniques can be used to measure uptake and efficacy of topical compounds in order to better understand their mode of action and improve therapeutic applications.

Parent-Reported Social Outcomes After Treatment for Pediatric Embryonal Tumors: A Prospective Longitudinal Study

To examine longitudinal parent-reported social outcomes for children treated for pediatric embryonal brain tumors. Patients (N=220) were enrolled onto a multisite clinical treatment protocol. Parents completed the Child Behavior Checklist/6-18 at the time of their child's diagnosis and yearly thereafter. A generalized linear mixed effects model regression approach was used to examine longitudinal changes in parent ratings of social competence, social problems, and withdrawn/depressed behaviors with demographic and treatment factors as covariates. During the 5-year period following diagnosis and treatment, few patients were reported to have clinically elevated scores on measures of social functioning. Mean scores differed significantly from population norms, yet remained within the average range. Several factors associated with unfavorable patterns of change in social functioning were identified. Patients with high-risk treatment status had a greater increase in parent-reported social problems (P=.001) and withdrawn/depressed behaviors (P=.01) over time compared with average-risk patients. Patients with posterior fossa syndrome had greater parent-reported social problems over time (P=.03). Female patients showed higher withdrawn/depressed scores over time compared with male patients (P<.001). Patient intelligence, age at diagnosis, and parent education level also contributed to parent report of social functioning. Results of this study largely suggest positive social adjustment several years after diagnosis and treatment of a pediatric embryonal tumor. However, several factors, including treatment risk status and posterior fossa syndrome, may be important precursors of long-term social outcomes. Future research is needed to elucidate the trajectory of social functioning as these patients transition into adulthood.