PeerJ
type: channel
link: https://peerj.com/articles/
description: Articles published in PeerJ
publisher: PeerJ Inc.
publication name: PeerJ
issn: 2167-8359
items: Prolonged growth and extended subadult development in the Tyrannosaurus rex species complex revealed by expanded histological sampling and statistical modeling
items: Phylogenetics within Camassia (Asparagaceae): examining difficult taxonomy and unusual variation using genomic restriction-site-associated DNA sequencing data
items: The simple multivariable model for predicting liver fibrosis in Vietnamese male adults: a combination of Bayesian model averaging and stepwise method
items: Examination of factors affecting insomnia in older victims of the Kumamoto earthquake
items: Genetic diversity and structure of the red squat lobster (Grimothea monodon) in the Humboldt Current Ecosystem using SNP markers
items: Independent effects of mental fatigue and drop height on drop jump performance in American football athletes: an exploration of central-peripheral interaction
items: Serum total testosterone and the prognosis of patients with advanced liver disease: a systemic review and meta-analysis
items: Effect of planting density and harvesting date on yield and quality of Artemisia argyi
items: Application of the Ballroom Aerobic Test protocol for assessing performance in standard-style dancesport athletes
items: Precision mapping of mandibular canal dimensions: cone beam computed tomography insights

Prolonged growth and extended subadult development in the Tyrannosaurus rex species complex revealed by expanded histological sampling and statistical modeling
type: item
type: AcademicArticle
description: Background Tyrannosaurus rex, one of the most iconic non-avialan dinosaurs, remains a central focus of paleobiological research. Growth modeling suggests T. rex exceeded 8,000 kg within two decades and had a lifespan approaching 30 years. However, this understanding of T. rex growth dynamics is dependent on single-point histological sampling of multiple skeletal elements and lacks specimens encompassing the earliest growth states. Methods We present the most comprehensive histological analysis of Tyrannosaurus ontogeny to date, based on transverse diaphyseal sections of femora and tibiae from 17 individuals ranging from small juveniles to large adults. Four alternative statistical models were tested, differing in the treatment of cortical growth marks, including annulus-like birefringent bands visible only in cross-polarized light. Due to high intraspecies morphological variability, the taxonomic status of many Tyrannosaurus specimens is debated, prompting use of the term “Tyrannosaurus rex species complex” to describe our dataset. Results The best-supported model incorporated all visible growth marks, produced the narrowest confidence bands, and indicated lower maximum growth rates and a delayed attainment of asymptotic size (~35–40 years) compared with earlier estimates. We also find that two immature specimens within the Tyrannosaurus rex species complex are not statistically compatible with the other growth series. Our approach is the first in dinosaur skeletochronology to simultaneously estimate the position of the earliest preserved growth mark across specimens, while fitting sigmoidal curves with simultaneous confidence bands. We find the inclusion of double growth marks and those visible only with cross polarized light provide better statistical model fits and this may have implications for modeling other taxa. Additionally, we find no strong link from extant vertebrates to support the idea that the growth inflection point is biologically significant and cor…
format: application/pdf
format: text/html
creator: Holly N. Woodward
creator: Nathan P. Myhrvold
creator: John R. Horner
subject: Paleontology
subject: Statistics
subject: Histology
description: doi:10.7717/peerj.20469
publisher: PeerJ Inc.
rights: © 2026 Woodward et al.
abstract: Background Tyrannosaurus rex, one of the most iconic non-avialan dinosaurs, remains a central focus of paleobiological research. Growth modeling suggests T. rex exceeded 8,000 kg within two decades and had a lifespan approaching 30 years. However, this understanding of T. rex growth dynamics is dependent on single-point histological sampling of multiple skeletal elements and lacks specimens encompassing the earliest growth states. Methods We present the most comprehensive histological analysis of Tyrannosaurus ontogeny to date, based on transverse diaphyseal sections of femora and tibiae from 17 individuals ranging from small juveniles to large adults. Four alternative statistical models were tested, differing in the treatment of cortical growth marks, including annulus-like birefringent bands visible only in cross-polarized light. Due to high intraspecies morphological variability, the taxonomic status of many Tyrannosaurus specimens is debated, prompting use of the term “Tyrannosaurus rex species complex” to describe our dataset. Results The best-supported model incorporated all visible growth marks, produced the narrowest confidence bands, and indicated lower maximum growth rates and a delayed attainment of asymptotic size (~35–40 years) compared with earlier estimates. We also find that two immature specimens within the Tyrannosaurus rex species complex are not statistically compatible with the other growth series. Our approach is the first in dinosaur skeletochronology to simultaneously estimate the position of the earliest preserved growth mark across specimens, while fitting sigmoidal curves with simultaneous confidence bands. We find the inclusion of double growth marks and those visible only with cross polarized light provide better statistical model fits and this may have implications for modeling other taxa. Additionally, we find no strong link from extant vertebrates to support the idea that the growth inflection point is biologically significant and cor…
bibliographic citation: Woodward et al. (2026) Prolonged growth and extended subadult development in the Tyrannosaurus rex species complex revealed by expanded histological sampling and statistical modeling. PeerJ 14:e20469 https://doi.org/10.7717/peerj.20469
date submitted: 2025-08-29
date accepted: 2025-11-03
issued: 2026-01-14
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Woodward
  given name: Holly N.
author list: Agent
  family name: Myhrvold
  given name: Nathan P.
author list: Agent
  family name: Horner
  given name: John R.
doi: 10.7717/peerj.20469
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-14
copyright: © 2026 Woodward et al.
attribution name: Woodward et al.

Phylogenetics within Camassia (Asparagaceae): examining difficult taxonomy and unusual variation using genomic restriction-site-associated DNA sequencing data
type: item
type: AcademicArticle
description: Premise Diversification of Camassia (Asparagaceae) in North America has shaped variety in morphological, ecological, and reproductive traits, and resulted in a classification with ambiguity in taxon boundaries, including numerous putative subspecies. Phylogenetic analyses of restriction-site-associated DNA sequences (RADseq) allowed new insights into its evolution and taxonomy, enhancing understanding of basal relationships, geographic patterns, taxonomic boundaries, and potential new species. Methods A total of 157 individuals in 71 populations across all 15 putative taxa of Camassia and 42 outgroup individuals in 21 populations from Hastingsia and Chlorogalum were sampled and genomic libraries were generated using the modified single-digest RADseq method known as multiplexed shotgun genotyping. Assembly in ipyrad included targeted comparisons across a range of parameters that influence homology assessment and amount of missing data, with analysis of the set of resulting datasets in RAxML and SVDquartets followed by comparison and summary across the sets of trees. Results and Conclusions Increasing the number of sampled loci improved phylogenetic signal despite concurrent increases in missing data. Each taxon was generally cohesive on the phylogenies, but some species and subspecies were not monophyletic. Results suggest that there was an early separation of C. howellii and C. leichtlinii from the rest of the genus during diversification. Different analysis parameters supported either a clade of both species as sister to the remainder of the genus, or C. howellii alone as sister. Relationships among all relatively deep clades within the genus were well supported. Within species, C. leichtlinii had particularly robust support for relationships compared to others in Camassia, and geographic patterns corresponding to the diversification of some subclades were resolved. The eight subspecies of C. quamash largely formed two main clades. Although most subspecies showed s…
format: application/pdf
format: text/html
creator: Jenny K. Archibald
creator: Susan R. Kephart
creator: Patrick J. Monnahan
creator: Kathryn E. Theiss
creator: Theresa M. Culley
subject: Biodiversity
subject: Evolutionary Studies
subject: Genetics
subject: Plant Science
subject: Taxonomy
description: doi:10.7717/peerj.20438
publisher: PeerJ Inc.
rights: © 2026 Archibald et al.
abstract: Premise Diversification of Camassia (Asparagaceae) in North America has shaped variety in morphological, ecological, and reproductive traits, and resulted in a classification with ambiguity in taxon boundaries, including numerous putative subspecies. Phylogenetic analyses of restriction-site-associated DNA sequences (RADseq) allowed new insights into its evolution and taxonomy, enhancing understanding of basal relationships, geographic patterns, taxonomic boundaries, and potential new species. Methods A total of 157 individuals in 71 populations across all 15 putative taxa of Camassia and 42 outgroup individuals in 21 populations from Hastingsia and Chlorogalum were sampled and genomic libraries were generated using the modified single-digest RADseq method known as multiplexed shotgun genotyping. Assembly in ipyrad included targeted comparisons across a range of parameters that influence homology assessment and amount of missing data, with analysis of the set of resulting datasets in RAxML and SVDquartets followed by comparison and summary across the sets of trees. Results and Conclusions Increasing the number of sampled loci improved phylogenetic signal despite concurrent increases in missing data. Each taxon was generally cohesive on the phylogenies, but some species and subspecies were not monophyletic. Results suggest that there was an early separation of C. howellii and C. leichtlinii from the rest of the genus during diversification. Different analysis parameters supported either a clade of both species as sister to the remainder of the genus, or C. howellii alone as sister. Relationships among all relatively deep clades within the genus were well supported. Within species, C. leichtlinii had particularly robust support for relationships compared to others in Camassia, and geographic patterns corresponding to the diversification of some subclades were resolved. The eight subspecies of C. quamash largely formed two main clades. Although most subspecies showed s…
bibliographic citation: Archibald et al. (2026) Phylogenetics within Camassia (Asparagaceae): examining difficult taxonomy and unusual variation using genomic restriction-site-associated DNA sequencing data. PeerJ 14:e20438 https://doi.org/10.7717/peerj.20438
date submitted: 2025-07-24
date accepted: 2025-10-31
issued: 2026-01-14
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Archibald
  given name: Jenny K.
author list: Agent
  family name: Kephart
  given name: Susan R.
author list: Agent
  family name: Monnahan
  given name: Patrick J.
author list: Agent
  family name: Theiss
  given name: Kathryn E.
author list: Agent
  family name: Culley
  given name: Theresa M.
doi: 10.7717/peerj.20438
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-14
copyright: ©2026 Archibald et al.
attribution name: Archibald et al.

The simple multivariable model for predicting liver fibrosis in Vietnamese male adults: a combination of Bayesian model averaging and stepwise method
type: item
type: AcademicArticle
description: Background Liver fibrosis is a significant health burden in Vietnamese male adults, driven by high rates of hepatitis B and hepatitis C, excessive alcohol consumption, and genetic and environmental factors. Despite progress in diagnostic tools, there is a pressing need for cost-effective screening methods tailored to this high-risk group, particularly in resource-limited settings. Methods This study enrolled 952 Vietnamese male adults over 40 years old undergoing FibroScan, excluding those with conditions affecting test accuracy. Data on demographics, clinical history, and anthropometrics were collected, and fibrosis stages were classified using the METAVIR system. Model development combined Bayesian model averaging and forward stepwise methods, with predictive performance validated via receiver operating characteristic (ROC) analysis and area under the curve (AUC) estimation in the R environment. Results Among 952 male participants, the prevalence of liver fibrosis was 19.9%, with most cases classified as mild (F1). Multivariate analysis identified significant risk factors, including advanced age (odds ratio (OR) = 1.6; 95% confidence interval (CI) [1.02–2.51]), alcohol abuse (OR = 4.44; 95% CI [2.65–7.42]), hepatitis B (OR = 6.76; 95% CI [3.14–14.54], hepatitis C (OR = 33.04; 95% CI [5.26–207.42]), family history of cirrhosis (OR = 16.14; 95% CI [3.28–79.55]), and hepatic steatosis (OR = 4.02; 95% CI [2.57–6.28]). The predictive model demonstrated good discriminative performance with an AUC of 0.769 (95% CI [0.734–0.800]) and showed satisfactory calibration through bootstrap resampling, indicating close agreement between predicted and observed risks. Conclusion The current prevalence of liver fibrosis among Vietnamese male adults was found to be 19.9%, and the developed risk prediction model effectively identifies high-risk individuals, enabling early diagnosis and targeted prevention, particularly in resource-limited settings. However, the lack of external valida…
format: application/pdf
format: text/html
creator: Nghia Nhu Nguyen
creator: Bao The Nguyen
creator: Huyen Thi Ngoc Le
creator: Hoang Nhat Dang
creator: Hao Minh Pham
creator: Duong Dai Ngo
creator: Duy Khanh Tran Nguyen
creator: Tam Thai Thanh Tran
creator: Hung Thanh Kim
creator: Tan Ngoc Huynh Mai
subject: Epidemiology
subject: Evidence Based Medicine
subject: Gastroenterology and Hepatology
subject: Internal Medicine
subject: Public Health
description: doi:10.7717/peerj.20435
publisher: PeerJ Inc.
rights: © 2026 Nguyen et al.
abstract: Background Liver fibrosis is a significant health burden in Vietnamese male adults, driven by high rates of hepatitis B and hepatitis C, excessive alcohol consumption, and genetic and environmental factors. Despite progress in diagnostic tools, there is a pressing need for cost-effective screening methods tailored to this high-risk group, particularly in resource-limited settings. Methods This study enrolled 952 Vietnamese male adults over 40 years old undergoing FibroScan, excluding those with conditions affecting test accuracy. Data on demographics, clinical history, and anthropometrics were collected, and fibrosis stages were classified using the METAVIR system. Model development combined Bayesian model averaging and forward stepwise methods, with predictive performance validated via receiver operating characteristic (ROC) analysis and area under the curve (AUC) estimation in the R environment. Results Among 952 male participants, the prevalence of liver fibrosis was 19.9%, with most cases classified as mild (F1). Multivariate analysis identified significant risk factors, including advanced age (odds ratio (OR) = 1.6; 95% confidence interval (CI) [1.02–2.51]), alcohol abuse (OR = 4.44; 95% CI [2.65–7.42]), hepatitis B (OR = 6.76; 95% CI [3.14–14.54], hepatitis C (OR = 33.04; 95% CI [5.26–207.42]), family history of cirrhosis (OR = 16.14; 95% CI [3.28–79.55]), and hepatic steatosis (OR = 4.02; 95% CI [2.57–6.28]). The predictive model demonstrated good discriminative performance with an AUC of 0.769 (95% CI [0.734–0.800]) and showed satisfactory calibration through bootstrap resampling, indicating close agreement between predicted and observed risks. Conclusion The current prevalence of liver fibrosis among Vietnamese male adults was found to be 19.9%, and the developed risk prediction model effectively identifies high-risk individuals, enabling early diagnosis and targeted prevention, particularly in resource-limited settings. However, the lack of external valida…
bibliographic citation: Nguyen et al. (2026) The simple multivariable model for predicting liver fibrosis in Vietnamese male adults: a combination of Bayesian model averaging and stepwise method. PeerJ 14:e20435 https://doi.org/10.7717/peerj.20435
date submitted: 2025-05-20
date accepted: 2025-10-30
issued: 2026-01-14
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Nguyen
  given name: Nghia Nhu
author list: Agent
  family name: Nguyen
  given name: Bao The
author list: Agent
  family name: Le
  given name: Huyen Thi Ngoc
author list: Agent
  family name: Dang
  given name: Hoang Nhat
author list: Agent
  family name: Pham
  given name: Hao Minh
author list: Agent
  family name: Ngo
  given name: Duong Dai
author list: Agent
  family name: Nguyen
  given name: Duy Khanh Tran
author list: Agent
  family name: Tran
  given name: Tam Thai Thanh
author list: Agent
  family name: Kim
  given name: Hung Thanh
author list: Agent
  family name: Mai
  given name: Tan Ngoc Huynh
doi: 10.7717/peerj.20435
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-14
copyright: ©2026 Nguyen et al.
attribution name: Nguyen et al.

Examination of factors affecting insomnia in older victims of the Kumamoto earthquake
type: item
type: AcademicArticle
description: Objective Post-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. Methods The 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. Results Persons 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. Discussion Support for insomnia requires both informal supports to prevent isolation based on mutual community support and formal support for those suspected of insomnia.
format: application/pdf
format: text/html
creator: Yumie Kanamori
creator: Tomonori Samiso
creator: Ayako Ide-Okochi
subject: Health Policy
subject: Nursing
subject: Public Health
subject: Mental Health
subject: Healthcare Services
description: doi:10.7717/peerj.20584
publisher: PeerJ Inc.
rights: © 2026 Kanamori et al.
abstract: Objective Post-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. Methods The 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. Results Persons 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. Discussion Support for insomnia requires both informal supports to prevent isolation based on mutual community support and formal support for those suspected of insomnia.
bibliographic citation: Kanamori et al. (2026) Examination of factors affecting insomnia in older victims of the Kumamoto earthquake. PeerJ 14:e20584 https://doi.org/10.7717/peerj.20584
date submitted: 2025-02-23
date accepted: 2025-11-24
issued: 2026-01-13
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Kanamori
  given name: Yumie
author list: Agent
  family name: Samiso
  given name: Tomonori
author list: Agent
  family name: Ide-Okochi
  given name: Ayako
doi: 10.7717/peerj.20584
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-13
copyright: ©2026 Kanamori et al.
attribution name: Kanamori et al.

Genetic diversity and structure of the red squat lobster (Grimothea monodon) in the Humboldt Current Ecosystem using SNP markers
type: item
type: AcademicArticle
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-popu…
format: application/pdf
format: text/html
creator: Marco Quispe-Machaca
creator: Carlos Muñoz-Ramírez
creator: Antonio Brante
creator: Pepe Espinoza
creator: Maximiliano Zilleruelo
creator: Gabriela Torres
creator: Ángel Urzúa
subject: Aquaculture, Fisheries and Fish Science
subject: Ecology
subject: Genetics
subject: Marine Biology
subject: Molecular Biology
description: doi:10.7717/peerj.20580
publisher: PeerJ Inc.
rights: © 2026 Quispe-Machaca et al.
abstract: 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-popu…
bibliographic citation: Quispe-Machaca et al. (2026) Genetic diversity and structure of the red squat lobster (Grimothea monodon) in the Humboldt Current Ecosystem using SNP markers. PeerJ 14:e20580 https://doi.org/10.7717/peerj.20580
date submitted: 2025-04-22
date accepted: 2025-11-22
issued: 2026-01-13
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Quispe-Machaca
  given name: Marco
author list: Agent
  family name: Muñoz-Ramírez
  given name: Carlos
author list: Agent
  family name: Brante
  given name: Antonio
author list: Agent
  family name: Espinoza
  given name: Pepe
author list: Agent
  family name: Zilleruelo
  given name: Maximiliano
author list: Agent
  family name: Torres
  given name: Gabriela
author list: Agent
  family name: Urzúa
  given name: Ángel
doi: 10.7717/peerj.20580
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-13
copyright: ©2026 Quispe-Machaca et al.
attribution name: Quispe-Machaca et al.

Independent effects of mental fatigue and drop height on drop jump performance in American football athletes: an exploration of central-peripheral interaction
type: item
type: AcademicArticle
description: Background This 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. Methods Twelve 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. Results Regarding 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). Conclusions Under 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.
format: application/pdf
format: text/html
creator: Zilong Wang
creator: Ziqi Feng
creator: Mengya Lu
creator: Jing Sun
creator: Tao Liu
creator: Qiuxia Zhang
creator: Xiangdong Wang
subject: Kinesiology
subject: Biomechanics
subject: Sports Injury
subject: Sports Medicine
description: doi:10.7717/peerj.20574
publisher: PeerJ Inc.
rights: © 2026 Wang et al.
abstract: Background This 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. Methods Twelve 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. Results Regarding 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). Conclusions Under 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.
bibliographic citation: Wang et al. (2026) Independent effects of mental fatigue and drop height on drop jump performance in American football athletes: an exploration of central-peripheral interaction. PeerJ 14:e20574 https://doi.org/10.7717/peerj.20574
date submitted: 2025-04-22
date accepted: 2025-11-20
issued: 2026-01-13
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Wang
  given name: Zilong
author list: Agent
  family name: Feng
  given name: Ziqi
author list: Agent
  family name: Lu
  given name: Mengya
author list: Agent
  family name: Sun
  given name: Jing
author list: Agent
  family name: Liu
  given name: Tao
author list: Agent
  family name: Zhang
  given name: Qiuxia
author list: Agent
  family name: Wang
  given name: Xiangdong
doi: 10.7717/peerj.20574
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-13
copyright: ©2026 Wang et al.
attribution name: Wang et al.

Serum total testosterone and the prognosis of patients with advanced liver disease: a systemic review and meta-analysis
type: item
type: AcademicArticle
description: Background Advanced 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. Methods Comprehensive 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). Results Eight 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). Conclusion Lower 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.
format: application/pdf
format: text/html
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
subject: Diabetes and Endocrinology
subject: Gastroenterology and Hepatology
description: doi:10.7717/peerj.20571
publisher: PeerJ Inc.
rights: © 2026 Zhang et al.
abstract: Background Advanced 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. Methods Comprehensive 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). Results Eight 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). Conclusion Lower 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.
bibliographic citation: Zhang et al. (2026) Serum total testosterone and the prognosis of patients with advanced liver disease: a systemic review and meta-analysis. PeerJ 14:e20571 https://doi.org/10.7717/peerj.20571
date submitted: 2025-04-22
date accepted: 2025-11-20
issued: 2026-01-13
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Zhang
  given name: Xiao-Yu
author list: Agent
  family name: Xu
  given name: Heng-Han
author list: Agent
  family name: Ma
  given name: Jian-Hui
author list: Agent
  family name: Liu
  given name: Yang
author list: Agent
  family name: Li
  given name: Han
author list: Agent
  family name: Tan
  given name: Hao-Qian
author list: Agent
  family name: Liu
  given name: Jun-Ying
doi: 10.7717/peerj.20571
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-13
copyright: ©2026 Zhang et al.
attribution name: Zhang et al.

Effect of planting density and harvesting date on yield and quality of Artemisia argyi
type: item
type: AcademicArticle
description: Background Field 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. Methods This 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. Results The 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. Conclusions Comprehensive analysis of essential oil content, down yield rate, eucalyptol content, borneol content, dry matte…
format: application/pdf
format: text/html
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
subject: Agricultural Science
subject: Biochemistry
subject: Ecology
subject: Environmental Sciences
subject: Plant Science
description: doi:10.7717/peerj.20565
publisher: PeerJ Inc.
rights: © 2026 He et al.
abstract: Background Field 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. Methods This 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. Results The 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. Conclusions Comprehensive analysis of essential oil content, down yield rate, eucalyptol content, borneol content, dry matte…
bibliographic citation: He et al. (2026) Effect of planting density and harvesting date on yield and quality of Artemisia argyi. PeerJ 14:e20565 https://doi.org/10.7717/peerj.20565
date submitted: 2025-07-25
date accepted: 2025-11-19
issued: 2026-01-13
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: He
  given name: Haiyan
author list: Agent
  family name: Yang
  given name: Dandan
author list: Agent
  family name: Zhang
  given name: Lixin
author list: Agent
  family name: Zhang
  given name: He
author list: Agent
  family name: Wang
  given name: Chaoze
author list: Agent
  family name: Yao
  given name: Nayuan
author list: Agent
  family name: Liu
  given name: Yanyan
author list: Agent
  family name: Li
  given name: Zhimin
author list: Agent
  family name: Zhang
  given name: Hongrui
doi: 10.7717/peerj.20565
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-13
copyright: ©2026 He et al.
attribution name: He et al.

Application of the Ballroom Aerobic Test protocol for assessing performance in standard-style dancesport athletes
type: item
type: AcademicArticle
description: Background Although 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. Methods Thirteen 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). Results No 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; <…
format: application/pdf
format: text/html
creator: Tamara Despot
creator: Davor Plavec
subject: Kinesiology
subject: Sports Medicine
description: doi:10.7717/peerj.20556
publisher: PeerJ Inc.
rights: © 2026 Despot and Plavec
abstract: Background Although 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. Methods Thirteen 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). Results No 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; <…
bibliographic citation: Despot et al. (2026) Application of the Ballroom Aerobic Test protocol for assessing performance in standard-style dancesport athletes. PeerJ 14:e20556 https://doi.org/10.7717/peerj.20556
date submitted: 2025-07-29
date accepted: 2025-11-18
issued: 2026-01-13
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Despot
  given name: Tamara
author list: Agent
  family name: Plavec
  given name: Davor
doi: 10.7717/peerj.20556
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-13
copyright: ©2026 Despot and Plavec
attribution name: Despot and Plavec

Precision mapping of mandibular canal dimensions: cone beam computed tomography insights
type: item
type: AcademicArticle
description: Background The 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. Methods This 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. Results BCT 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. Conclusion This 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.
format: application/pdf
format: text/html
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
subject: Anatomy and Physiology
subject: Dentistry
subject: Evidence Based Medicine
subject: Radiology and Medical Imaging
subject: Surgery and Surgical Specialties
description: doi:10.7717/peerj.20553
publisher: PeerJ Inc.
rights: © 2026 Elboraey et al.
abstract: Background The 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. Methods This 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. Results BCT 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. Conclusion This 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.
bibliographic citation: Elboraey et al. (2026) Precision mapping of mandibular canal dimensions: cone beam computed tomography insights. PeerJ 14:e20553 https://doi.org/10.7717/peerj.20553
date submitted: 2025-09-08
date accepted: 2025-11-18
issued: 2026-01-13
is part of: PeerJ
license: https://creativecommons.org/licenses/by/4.0/
author list: Agent
  family name: Elboraey
  given name: Mohamed Omar
author list: Agent
  family name: Essa
  given name: Emad El Said Fahim
author list: Agent
  family name: Fayad
  given name: Mostafa Ibrahim
author list: Agent
  family name: Alolayan
  given name: Albraa Badr
author list: Agent
  family name: Kabli
  given name: Ahmed Mohamed
author list: Agent
  family name: Alqhtani
  given name: Abdullah
author list: Agent
  family name: Elhelbawy
  given name: Nahla Gamaleldin
author list: Agent
  family name: Ibrahim
  given name: Tarek Mohamed
doi: 10.7717/peerj.20553
volume: 14
issn: 2167-8359
publication name: PeerJ
publication date: 2026-01-13
copyright: ©2026 Elboraey et al.
attribution name: Elboraey et al.

PeerJ
type: Periodical
uri: PeerJ
issn: 2167-8359