title: PeerJ description: Articles published in PeerJ link: https://peerj.com/articles/index.rss3?journal=peerj creator: info@peerj.com PeerJ errorsTo: info@peerj.com PeerJ language: en title: Examination of factors affecting insomnia in older victims of the Kumamoto earthquake link: https://peerj.com/articles/20584 last-modified: 2026-01-13 description: ObjectivePost-disaster survivors are prone to increased risks related to mental disorders such as insomnia and depression. In addition, it has been recently noted that elderly people have difficulty falling asleep and waking up in the middle of the night, decreasing sleep efficiency. Therefore, there is a need to understand the actual situation of insomnia among the older persons affected after the earthquake and consider appropriate support. However, the actual situation after the Kumamoto earthquake in 2016 has not been clarified. Therefore, this study aimed to examine the factors affecting insomnia among the older adults affected by the Kumamoto earthquake.MethodsThe study included 4,758 persons (2,010 men and 2,748 women; mean age 75.36 ± 7.33 years) aged 65 years or older among those who had moved out of temporary housing in Kumamoto City. The survey was a self-administered questionnaire sent by mail. The independence of each variable was confirmed using the χ2 test. Binomial logistic regression analysis was used to examine factors influencing insomnia.ResultsPersons significantly more likely to report insomnia had the following characteristics: age ≥ 75, no exercise habits, not eating three times a day, no appetite, eating alone, not participating in community activities, not knowing information about community activities, no one to talk to, no family to talk to, and no coworkers to talk to. Conversely, those less likely to fall into the insomnia category had the following attributes: men, those who had no employers, those who consulted friends, those who consulted a medical institution, those who consulted a care welfare office, and those who consulted city hall. Additionally, the respondents were more likely to report insomnia when they moved out of the community.DiscussionSupport for insomnia requires both informal supports to prevent isolation based on mutual community support and formal support for those suspected of insomnia. creator: Yumie Kanamori creator: Tomonori Samiso creator: Ayako Ide-Okochi uri: https://doi.org/10.7717/peerj.20584 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Kanamori et al. title: Genetic diversity and structure of the red squat lobster (Grimothea monodon) in the Humboldt Current Ecosystem using SNP markers link: https://peerj.com/articles/20580 last-modified: 2026-01-13 description: The Humboldt Current Ecosystem (HCE) presents a wide variability of environmental and geographic conditions that play an important role in marine invertebrates, modulating variations not only in their behavior, physiology and morphology; but also changes in their patterns of genetic differentiation. Therefore, it is necessary to characterize genetic diversity and structure to develop management and conservation strategies in commercially important invertebrates such as the red squat lobster Grimothea monodon, which in the HCE presents two highly contrasting morphotypes and/or lifestyles (pelagic vs. benthic). The objective of the present study was to evaluate the diversity, structure, and genetic connectivity of the G. monodon population along the latitudinal gradient in the HCE using single nucleotide polymorphism (SNP) markers. Low heterozygosity (0.05 ± 0.1) and similar allelic richness among all studied populations (∼1.09) were observed. However, a slightly higher inbreeding was recorded in individuals from the Concepción population. At the level of genetic structure, using LEA and STRUCTURE, it is confirmed that G. monodon is a single population unit between the pelagic and benthic morphotypes, and that the difference observed in the discriminant analysis of principal components (DPCA) is due to the geographic distance (isolation by distance) between the extreme southern locations of the HCE (Constitución-Concepción: verified by Analysis of Molecular Variance (AMOVA) and Mantel test). The slight difference observed mainly in Concepción is due to inbreeding, however, this tends to be very low due to the high genetic flow explained by the prolonged development time of their planktonic larvae, which can positively influence an optimal recovery of their natural populations along the latitudinal gradient. This study emphasizes that the slight genetic differentiation of G. monodon could be due only to its wide geographic distribution range, generating only intra-population variability and not inter-population variability. This is due to the high dispersal potential of their planktonic larvae, which converges as a development trait of early ontogeny for both morphotypes and/or lifestyles of this squat lobster. creator: Marco Quispe-Machaca creator: Carlos Muñoz-Ramírez creator: Antonio Brante creator: Pepe Espinoza creator: Maximiliano Zilleruelo creator: Gabriela Torres creator: Ángel Urzúa uri: https://doi.org/10.7717/peerj.20580 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Quispe-Machaca et al. title: Independent effects of mental fatigue and drop height on drop jump performance in American football athletes: an exploration of central-peripheral interaction link: https://peerj.com/articles/20574 last-modified: 2026-01-13 description: BackgroundThis study aimed to investigate the effects of mental fatigue (MF) and different drop heights on the athletic performance of American football players executing the drop jump (DJ) movement.MethodsTwelve male American football athletes were selected as subjects. The Vicon infrared three-dimensional motion capture and analysis system, Kistler three-dimensional force platform, and other instruments were used. MF was induced through a Stroop task, and the DJ performance of the subjects was tested at drop heights of 30 cm, 40 cm, and 50 cm. A 2 × 3 repeated measures analysis of variance was employed.ResultsRegarding different jump heights, both under MF and baseline conditions, 40 cm and 50 cm heights resulted in lower jump heights compared to the 30 cm height (p = 0.002, p = 0.008); in terms of the rate of force development (RFD) metric, both under MF and baseline conditions, 40 cm and 50 cm heights showed lower RFD compared to the 30 cm height (p < 0.001); in the average power output metric, compared to the baseline, MF resulted in lower average power output across different drop heights (p < 0.001); in the reactive strength index (RSI) metric, compared to the baseline, MF resulted in lower RSI across different drop heights (p = 0.001), and compared to the 30 cm height, 40 cm and 50 cm heights showed lower RSI (p = 0.004, p = 0.008); in the Reactive Strength Ratio (RSR) metric, compared to the baseline, MF resulted in lower RSR across different drop heights (p = 0.001); in the Kleg metric, compared to the 30 cm height, 40 cm and 50 cm heights showed higher Kleg (p = 0.001, p = 0.008).ConclusionsUnder MF conditions, athletes’ performance in average power output, RSI, and RSR declined, suggesting a reduction in central nervous system efficiency. Additionally, increasing the drop height to 40 cm or above significantly reduced jump height and RFD, and increased Kleg. However, no interactive effects between MF and drop height were observed. creator: Zilong Wang creator: Ziqi Feng creator: Mengya Lu creator: Jing Sun creator: Tao Liu creator: Qiuxia Zhang creator: Xiangdong Wang uri: https://doi.org/10.7717/peerj.20574 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Wang et al. title: Serum total testosterone and the prognosis of patients with advanced liver disease: a systemic review and meta-analysis link: https://peerj.com/articles/20571 last-modified: 2026-01-13 description: BackgroundAdvanced liver disease (ALD) is associated with significant morbidity and mortality worldwide. Emerging evidence suggests that sex hormonal imbalances, particularly low serum total testosterone (TT) levels, may influence the prognosis of patients with ALD. This meta-analysis aimed to evaluate the association between serum TT levels and the prognosis of patients with ALD.MethodsComprehensive searches of PubMed, Embase, and Web of Science were performed from the inception of the searched databases up to November 13, 2025, to identify observational studies assessing the association between serum TT levels and the risk of all-cause mortality or liver transplant (LT) among patients with ALD. Pooled risk ratios (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model to account for the potential influence of heterogeneity. This systematic review was registered in PROSPERO (CRD42024578870).ResultsEight cohort studies encompassing 1,989 patients were included in the analysis. Findings demonstrated that low serum TT levels were significantly associated with an increased risk of all-cause mortality or LT during follow-up (RR: 1.87, 95% CI [1.57–2.23], p < 0.001; I2 = 0%). Sensitivity analyses, including those limited to male patients, confirmed the stability of these results. Subgroup analyses revealed consistent associations across various study designs, geographic regions, patient ages, TT cutoff values, follow-up durations, and quality assessments (p for subgroup difference, all > 0.05).ConclusionLower serum TT levels are significantly associated with a higher risk of all-cause death or LT in patients with ALD, indicating their potential utility as prognostic biomarkers. creator: Xiao-Yu Zhang creator: Heng-Han Xu creator: Jian-Hui Ma creator: Yang Liu creator: Han Li creator: Hao-Qian Tan creator: Jun-Ying Liu uri: https://doi.org/10.7717/peerj.20571 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Zhang et al. title: Effect of planting density and harvesting date on yield and quality of Artemisia argyi link: https://peerj.com/articles/20565 last-modified: 2026-01-13 description: BackgroundField investigations revealed that during the production of Artemisia argyi Lévl. et Vant. excessive planting density and untimely harvesting lead to desiccation and abscission of leaves in the middle and lower plant sections. The height of these withered leaves (dead leaf height) accounted for over 50% of the plant height, significantly reducing both the yield and quality of the medicinal herb A. argyi leaves.MethodsThis study employed field experiments using Nanyang A. argyi as the test material. Agronomic traits (including plant height, canopy width, number of effective leaves on the main stem, dead leaf height, stem diameter, internode length, and yield) and quality indicators (including volatile oil content, moxa yield rate, eucalyptol content, borneol content, and total flavonoid content) were measured under different planting density treatments and at different harvest times.ResultsThe results demonstrated that reducing planting density promoted sturdier plant growth, increased the number of effective leaves on the main stem, decreased the dead leaf height, and increased the dry matter ratio of the A. argyi leaves. As the harvest time was delayed, the number of effective leaves on the main stem, dead leaf height, and yield all gradually increased. The volatile oil content, eucalyptol content, and borneol content in A. argyi leaves increased gradually with decreasing planting density. These same components initially increased and then decreased as the harvest time was extended. Conversely, the combustion calorific value of A. argyi down, total flavonoid content, polysaccharide content, and polyphenol content generally decreased gradually with reduced density. The combustion calorific value, total flavonoid content, and polyphenol content also exhibited an initial increase followed by a decrease with prolonged harvest time.ConclusionsComprehensive analysis of essential oil content, down yield rate, eucalyptol content, borneol content, dry matter ratio, and yield across different densities and harvest periods indicated that for spring-planted A. argyi, a planting spacing of 20 cm × 40 cm combined with harvesting one week after the Dragon Boat Festival resulted in superior overall quality and higher yield. creator: Haiyan He creator: Dandan Yang creator: Lixin Zhang creator: He Zhang creator: Chaoze Wang creator: Nayuan Yao creator: Yanyan Liu creator: Zhimin Li creator: Hongrui Zhang uri: https://doi.org/10.7717/peerj.20565 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 He et al. title: Application of the Ballroom Aerobic Test protocol for assessing performance in standard-style dancesport athletes link: https://peerj.com/articles/20556 last-modified: 2026-01-13 description: BackgroundAlthough the existing field-based tests to assess functional capacity in dancesport have been developed, most of them have been applied to ballet or contemporary dancesport athletes at the individual level, while little evidence is available for dancesport couples in standard dance disciplines. Therefore, the main purpose of this study was to examine the test-retest reliability and usefulness of the progressive Ballroom Aerobic Test (BAT) protocol for assessing aerobic performance.MethodsThirteen standard dancesport athletes (six pairs and one individual male participant; age: 20.1 ± 3.8 years; height: 175.0 ± 8.2 cm; weight: 64.3 ± 9.7 kg; males; age: 19.9 ± 3.7 years; height: 180.0 ± 4.7 cm; weight: 70.2 ± 8.7 kg; body mass index: 21.5 ± 1.8 kg/m2 training experience: 8.6 ± 5.1 years; females; age: 20.3 ± 4.0 years; height: 168.5 ± 6.5 cm; weight: 57.5 ± 5.5 kg; body mass index: 20.2 ± 1.3 kg/m2; training experience: 8.5 ± 3.4 years) took part in the study. All participants were members of certified dancesport clubs who competed at national and international levels. The BAT protocol consisted of five stages, each corresponding to one of five standard dancesport disciplines (English Waltz, Slow Foxtrot, Tango, Viennese Waltz, and Quickstep). A test-retest design, with one week between trials, was used to examine the reliability measures. Ventilatory and metabolic parameters were derived from MetaMax® 3B, a reliable and valid portable gas analyzer. Reliability measures included Cohen D effect size (ES), intra-class correlation coefficient (ICC), coefficient of variation (CV), typical error (TE) and smallest worthwhile change (SWC).ResultsNo significant differences were observed between test and retest sessions (P > 0.05). ESs ranged from trivial to small (0.00–0.47) with ‘very good’ to ‘excellent’ reliability (ICC = 0.80–0.99; CV = 1.63–4.85%). The usefulness of the BAT protocol was generally rated as ‘ok’ to ‘good’ for speed (TE = 2.76; SWC = 3.20; <), absolute VO2 (TE = 0.14; SWC = 0.15; <), respiratory exchange ratio (RER; TE = 0.02; SWC = 0.02; =), tidal volume (VT = 0.06; SWC = 0.06; =), and dead space to tidal volume ratio (VD/VT; TE = 0.01; SWC = 0.01; =).ConclusionCurrent findings suggest that the BAT protocol is a reliable and useful tool for assessing aerobic capacity in standard-style dancesport athletes. Moreover, the BAT protocol can accurately detect meaningful individual changes, particularly for speed (3.20 bpm), absolute VO2 (0.15 L*min−1), and VE (4.87 L). These results may assist athletes and strength and conditioning coaches in monitoring and tracking ‘real’ time changes to optimize the training process. creator: Tamara Despot creator: Davor Plavec uri: https://doi.org/10.7717/peerj.20556 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Despot and Plavec title: Precision mapping of mandibular canal dimensions: cone beam computed tomography insights link: https://peerj.com/articles/20553 last-modified: 2026-01-13 description: BackgroundThe purpose of this study was to provide detailed anatomical localization of the inferior alveolar canal (IAC) in the mandible area using cone beam computed tomography (CBCT) in the Saudi population, with particular considerations including buccal cortex thickness (BCT), IAC diameter, mental foramen position (MF), and buccal shift patterns of the IAC.MethodsThis retrospective split-mouth study analyzed 126 CBCT scans of 63 males and 63 females between the age group of 18 to 65 years from the faculty of Dentistry, Taibah University, Saudi Arabia. Measurements included BCT at nine points between the first premolar and third molar area, IAC diameter, the closest point of IAC to the mandibular lower border, MF position in relation to premolar apices and mandibular border, and the location of buccal shifting of the IAC. Statistics were calculated with Student’s t-test and paired t-test with the level of significance at p ≤ 0.05.ResultsBCT showed a progressive increase from anterior to posterior regions in both genders, with the thickest measurements at the second and third molar regions (maximum: 6.05 ± 1.34 mm in females). The MF position showed considerable individual variation, with 10% of female subjects exhibiting a coronal position relative to premolar apices. The IAC diameter ranged from 2.43 to 3.80 mm. The closest position of the IAC to the lower border was mostly in the second molar area, with the shortest distances being 2.50–3.40 mm. The canal primarily exhibited a buccal shift in the second molar region in 60–81.8% of the subjects.ConclusionThis study provides comprehensive anatomical mapping of the mandibular region, highlighting considerable individual variation in key anatomical parameters. The findings have significant clinical implications for various dental and maxillofacial procedures. creator: Mohamed Omar Elboraey creator: Emad El Said Fahim Essa creator: Mostafa Ibrahim Fayad creator: Albraa Badr Alolayan creator: Ahmed Mohamed Kabli creator: Abdullah Alqhtani creator: Nahla Gamaleldin Elhelbawy creator: Tarek Mohamed Ibrahim uri: https://doi.org/10.7717/peerj.20553 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Elboraey et al. title: Spatial and host-specific structuring in symbiont community composition of an endemic Hawaiian octocoral, Sarcothelia edmondsoni (Verrill 1928) link: https://peerj.com/articles/20549 last-modified: 2026-01-13 description: Coral reefs are increasingly threatened by climate-induced bleaching, yet some taxa—like the Hawaiian endemic octocoral Sarcothelia edmondsoni—exhibit notable stress tolerance. This study investigates whether distinct color morphotypes (blue and brown) of S. edmondsoni maintain stable or flexible symbiont associations that might underlie this resilience. Using high-throughput ITS2 sequencing and SymPortal analyses, we characterized Symbiodiniaceae communities across morphotypes on three Hawaiian Islands. Assemblages were overwhelmingly dominated (>99%) by Symbiodinium (Clade A), particularly S. tridacnidorum (ITS2 type A3), with blue morphotypes consistently hosting more diverse symbiont profiles. Dinoflagellate community composition varied significantly by morphotype and location, with no ITS2 profile shared across all morphotype–island combinations. Bray–Curtis analyses revealed strong ecological structuring, while UniFrac (a measure of evolutionary relatedness) indicated phylogenetic similarity, suggesting intragenomic or ecotypic divergence within a conserved lineage. Morphotype-specific associations may reflect environmental adaptation or host–symbiont specificity. The greater symbiont diversity in blue morphotypes, coupled with the lack of profile overlap among sites, points to fine-scale host–symbiont structuring shaped by local environmental conditions. These results demonstrate that Sarcothelia edmondsoni hosts morphotype- and location-specific Symbiodiniaceae communities within a conserved lineage, revealing fine-scale ecological structuring and potential symbiont ecotypes that may contribute to this species’ resilience across variable reef environments. This study supports previous findings that symbiont community structure is shaped by the combined influence of host specificity and local environmental conditions. creator: Erika M. Cabell creator: Cynthia L. Hunter uri: https://doi.org/10.7717/peerj.20549 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Cabell and Hunter title: Mapping quality of life in Norway: psychometric evaluation and network analysis of 15,148 responses from a public health study link: https://peerj.com/articles/20529 last-modified: 2026-01-13 description: BackgroundThe Norwegian Quality of Life Study (NQoLS) was established to inform public health policy by assessing self-reported health (SRH) and quality of life (QoL) outcomes across the general population, identifying factors that influence these outcomes, and highlighting vulnerable groups. In this study, we assessed the psychometric properties of the NQoLS measures and applied network analysis to explore the structural relationships among outcome variables.MethodsThe 2022 NQoLS is a cross-sectional study that included 15,148 adults from the general adult Norwegian population. No exclusion criteria were specified beyond the requirement that participants have a registered address, email, and/or phone number. The study assessed SRH and QoL through single- and multi-item measures across physical, psychological, and social domains. The psychometric evaluation included descriptive statistics, reliability testing, confirmatory factor analysis, and correlation analysis, followed by a network analysis to map how outcomes connect and cluster.ResultsMeasures generally demonstrated acceptable reliability and validity. Model fit for multi-item scales was generally adequate following minor modifications. Network analysis identified a central cluster, including the Satisfaction with life scale, Hopkins Symptom Checklist-5, and Satisfaction with psychological health. These indicators were highly connected and structurally central. In contrast, physical health variables, including Satisfaction with physical health, Pain and discomfort, and General health, were more weakly connected and positioned at the network periphery. The sensitivity analysis, stratified by language preference, yielded results consistent with those of the entire sample.ConclusionsThe NQoLS provides a foundation for mapping SRH and QoL. Most measures worked well, though a few could be fine-tuned for a better fit and sensitivity. Based on our assessment and the structure revealed by the network analysis, physical health appears to be relatively underrepresented in the current survey, suggesting a potential area for future enhancement. creator: John Roger Andersen creator: Tone Nygaard Flølo creator: Kari Hanne Gjeilo creator: Käthe Meyer creator: Tone Merete Norekvål creator: Gudrun Rohde uri: https://doi.org/10.7717/peerj.20529 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Andersen et al. title: Efficacy and safety of pyrotinib-based regimens in patients with HER2-positive stage III/IV breast cancer: a real-world retrospective study in China link: https://peerj.com/articles/20524 last-modified: 2026-01-13 description: BackgroundData from multiple clinical trials have shown that pyrotinib has demonstrated significant efficacy and acceptable tolerability in patients with HER2-positive advanced breast cancer (BC). However, the short time to market in China limits our comprehensive understanding of the drug’s long-term efficacy and potential adverse events (AEs) from the drug. Therefore, this study analyzed the clinical efficacy and safety of pyrotinib-based regimens in a real-world database.Materials and MethodsThis study retrospectively analyzed patients with HER2-positive stage III/IV BC who were treated with pyrotinib-based regimens from October 2018 to October 2022 at the Affiliated Tumor Hospital of Guangxi Medical University. Tumor assessments were based on RECIST 1.1, and AEs were assessed and graded according to NCI-CTCAE 5.0. Long-term efficacy was evaluated by calculating median progression-free survival (mPFS, defined as the time from treatment initiation until disease progression or death).ResultsOf the 37 included patients, the objective response rate (ORR) was 62.2%, the disease control rate (DCR) was 94.6%, and the median progression-free survival length was 12.0 months (95% CI [5.8 ∼18.2] months). A subgroups comparison found that significant differences were observed in patients who had not used lapatinib (P = 0.016), had a number of metastatic sites ≤ 2 (P = 0.011), were intolerant to trastuzumab (P = 0.004), and were on first-line pyrotinib treatment (P = 0.036), with these patients having median progression-free survival lengths of 13.0 months, 15.9 months, 23.5 months, and 23.5 months, respectively. Pyrotinib was also effective in patients with advanced brain metastases after multiple lines of complex therapy, with these patients having a median progression-free survival length of 5.0 months. Diarrhea was the most common adverse event (97.3%), with no grade 4 AEs observed. This study was the first to compare the relationship between different degrees of diarrhea and mPFS, and no significant differences in mPFS were observed (P = 0.291). In addition, a rare positive fecal occult blood profile (5.4%) was observed.ConclusionPyrotinib-based regimens have shown satisfactory clinical efficacy in HER2-positive stage III/IV BC patients, and pyrotinib is well tolerated with manageable adverse events. creator: Limin Zhi creator: Lei Huang creator: Xiaohong Pang creator: Qiong Wu creator: Yu Lei uri: https://doi.org/10.7717/peerj.20524 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2026 Zhi et al.