title: PeerJ description: Articles published in PeerJ link: https://peerj.com/articles/index.rss3?journal=peerj&page=699 creator: info@peerj.com PeerJ errorsTo: info@peerj.com PeerJ language: en title: The relationship between the accuracy of curling athletes’ duration judgment and delivery performance link: https://peerj.com/articles/13541 last-modified: 2022-06-14 description: ObjectiveTime perception is a critical point for curling athletes to have in order to successfully complete interactions between themselves and their environment. Exploring the relationship between the accuracy of duration judgment and curling athletes’ performance is helpful to reveal the influencing factors on their performance and to provide a reference for the training of athletes’ delivery performance.MethodsThirty curling athletes and 30 non-athletes were recruited as participants. Using 3D modeling technology, curling videos of different situations were presented to the participants as stimulus information, and the participants were required to complete the duration judgment task. The neural activation of the participants during the entire process of duration judgment was recorded using electroencephalogram (EEG) equipment. The performance of the 30 curlers participating in the experiment was measured. Variance analyses were conducted on the collected behavioral and EEG data, and correlation and regression analyseswere conducted between behavioral data and delivery performance.ResultsThe accuracy of the distance judgment of curlers was higher than that of non-curlers (P < 0.05). In the stimulus video presentation stage, the power in the alpha band of curlers was higher than that of non-athletes (P < 0.05). In the task decision stage, the power in the alpha band of curlers was higher than that of non-athletes (P < 0.05), and the power in the theta band was higher than that of non-athletes (P < 0.05). There was a correlation between the accuracy of the curlers’ perception of specific situational time intervals and the accuracy of delivery (P < 0.05). Regression analysis results were y = 3.422 + 1.415x.ConclusionThe accuracy of curling athletes’ duration judgment is high in a specific situation. There is a correlation between the accuracy of duration judgment and delivery performance in a specific situation: the higher the accuracy of specific duration perception, the higher the performance accuracy of delivery. The cognitive strategies adopted by curlers differ from those adopted by non-athletes in the completion of duration judgment. Specifically, in a specific situation, fewer attention resources are utilized in the stimulus presentation and decision-making stages, while more memory resources are utilized in the decision-making stage to ensure higher accuracy of interval judgment. This study provides a new idea for exploring the causes of curling athletes’ excellent technical performance and provides a reference for future curling research on competition training practice. Given the limitations of mobile EEG devices in this study, future studies can measure neural activity during actual delivery preparation and execution in an environment of high ecological validity to obtain more direct evidence. creator: Minjia Song creator: Qiwei Zhao creator: Chunhua Du creator: Chenglin Zhou creator: Ruitao Li uri: https://doi.org/10.7717/peerj.13541 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Song et al. title: Droplet distribution in cotton canopy using single-rotor and four-rotor unmanned aerial vehicles link: https://peerj.com/articles/13572 last-modified: 2022-06-14 description: Unmanned aerial vehicles (UAVs) are widely used as the sprayers for low-volume pesticide application in recent years. Droplet distribution characteristics of UAV spraying in the cotton canopy have notable effect on the biological control efficacy of the targets and the defoliation efficiency of the harvest aids. In this work, the influences on droplet distribution in the cotton canopy with respect to the flight height, forward mode, and spraying volume were evaluated by conducting the field trials during two cotton growth stages in 2020, respectively. The first field trial was performed in the cotton flowering stage and the second one was conducted in the early boll development stage. Two typical UAVs equipped with a single-rotor and four-rotor, respectively, were adopted as the spraying platforms in this work. Droplet deposition obtained by water sensitive papers (WSPs) clipped on the cotton leaves was considered as the observing metric. All cotton leaves in the canopy were divided into three groups (i.e., upper, middle, and bottom layers) in both trials. Furthermore, the cotton canopy was divided as eight directions to assess the droplet distribution in the canopy from different directions. The results showed that the droplet deposition varied remarkable between the treatments and in the same canopy within a treatment. The upper layer obtained higher droplet deposition than those of the middle and bottom layers and plants P4 to P8 accessed more droplets than those of the remaining sampling plants in most treatments of both trials for the two UAVs. The upper layer droplet deposition of the four-rotor UAV treatments outperformed that of the single-rotor treatments under the same operating parameters. The forward modes rarely affected the droplet distribution of the four-rotor UAV treatments but significantly influenced that of the single-rotor UAV treatments. For the single-rotor UAV spraying with “head forward”, the droplet distribution of the treatment with a flight height of 2 m was more even than that of the 1 and 3 m in the first trial. Under the same flight height, droplet deposition of the treatments with a spraying volume of 22.5 L ha−1 was remarkably higher than that of the 12 L ha−1 for both forward modes in the second trial. “Tail forward” of the single-rotor UAV treatment had better penetration at a flight height of 2 m in both trials. Therefore, for the single-rotor UAV, under a flight height of 2 m and a spraying volume of 22.5 L ha−1, “tail forward” was recommended for applying pesticides to control targets at the lower canopy and “head forward” was a better choice for harvest aid application. Four-rotor UAV was a suitable adoption for the harvest aid application and controlling the targets of the upper canopy. The results also indicate that the systemic pesticides are recommended for UAV spraying due to its uneven droplet distribution uniformity in the whole cotton canopy. creator: Yanhua Meng creator: Yan Ma creator: Zhiguo Wang creator: Hongyan Hu uri: https://doi.org/10.7717/peerj.13572 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Meng et al. title: AntiDMPpred: a web service for identifying anti-diabetic peptides link: https://peerj.com/articles/13581 last-modified: 2022-06-14 description: Diabetes mellitus (DM) is a chronic metabolic disease that has been a major threat to human health globally, causing great economic and social adversities. The oral administration of anti-diabetic peptide drugs has become a novel route for diabetes therapy. Numerous bioactive peptides have demonstrated potential anti-diabetic properties and are promising as alternative treatment measures to prevent and manage diabetes. The computational prediction of anti-diabetic peptides can help promote peptide-based drug discovery in the process of searching newly effective therapeutic peptide agents for diabetes treatment. Here, we resorted to random forest to develop a computational model, named AntiDMPpred, for predicting anti-diabetic peptides. A benchmark dataset with 236 anti-diabetic and 236 non-anti-diabetic peptides was first constructed. Four types of sequence-derived descriptors were used to represent the peptide sequences. We then combined four machine learning methods and six feature scoring methods to select the non-redundant features, which were fed into diverse machine learning classifiers to train the models. Experimental results show that AntiDMPpred reached an accuracy of 77.12% and area under the receiver operating curve (AUCROC) of 0.8193 in the nested five-fold cross-validation, yielding a satisfactory performance and surpassing other classifiers implemented in the study. The web service is freely accessible at http://i.uestc.edu.cn/AntiDMPpred/cgi-bin/AntiDMPpred.pl. We hope AntiDMPpred could improve the discovery of anti-diabetic bioactive peptides. creator: Xue Chen creator: Jian Huang creator: Bifang He uri: https://doi.org/10.7717/peerj.13581 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Chen et al. title: Acidification does not alter the stable isotope composition of bone collagen link: https://peerj.com/articles/13593 last-modified: 2022-06-14 description: In this study, we compared the elemental and isotopic composition of modern and ancient bone samples pre-treated using different demineralization agents with acidic and neutral pH. The purpose of our research was to examine if demineralization using a mineral acid such as hydrochloric acid (HCl) significantly alters the δ15N and δ13C values of bone collagen. Evidence from the elemental and amino acid composition of the samples were incorporated alongside isotopic compositions to provide a holistic view of the effect of demineralization agents on the composition of bone collagen. The stable isotope compositions of collagen extracts were also compared against equivalent whole bone samples to assess whether whole bone has a stable isotope composition that is comparable to collagen demineralized with a neutral agent. Our results demonstrate that bone demineralization using either ethylenediaminetetraacetic acid (EDTA) or HCl yields collagen extracts with stable isotope compositions that are not significantly different, indicating that mineral acid does not alter δ15N and δ13C values of bone collagen. The results comparing whole bone and extracted collagen stable isotope compositions indicate that whole bone cannot be used as an effective replacement for bone collagen due to the significantly different stable isotope compositions between these sample materials. In ecological and archaeological studies performing stable isotope analysis on bone, sample pre-treatment to isolate collagen is a necessity to obtain the most reliable and reproducible isotopic measurements. creator: Tess Wilson creator: Paul Szpak uri: https://doi.org/10.7717/peerj.13593 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Wilson and Szpak title: Root traits in Crambe abyssinica Hochst and Raphanus sativus L. plants are associated with differential tolerance to water deficit and post-stress recovery link: https://peerj.com/articles/13595 last-modified: 2022-06-14 description: BackgroundPrevious studies have shown that Crambe abyssinica and Raphanus sativus are physiologically tolerant to water deficits; however, there is a lack of information on the mechanisms responsible for their tolerance regarding root morphological characteristics. This study aimed to characterize morphological changes in the root system of C. abyssinica and R. sativus subjected water deficit, as well as to identify the responses that improve tolerance and post-stress recovery capacity of these plants.MethodsIndependent experiments for each specieswere performed in a controlled greenhouse, where plants were randomly set in a randomized block design with five replicates. Plants of C. abyssinica and R. sativus were cultivated in pots and exposed to well-watered treatment (WW; 90% water holding capacity–WHC of the substrate) or water deficit (WD; 40% WHC) conditions, at 28 days after planting. The plants were kept under WD for 7, 14, or 21 days with rehydration soon after each episode of water deficit. Assessment of water relations, biomass allocation, leaf and root system morphological characteristics and gas exchange were performed after each period of water deficit and 48 h after rehydration.ResultsThe water deficit reduced the water status of both species, and morphological and biomass allocation were not recovered after rehydration. Photosynthesis of C. abyssinica decreased with prolonged water deficit, which was also not recovered after rehydration. In R. sativus, photosynthesis was not altered by WD for 21 days, and a higher WUE was recorded. Root morphology of R. sativus was mainly affected at 14 days of WD, while the traits related to very fine roots increased at 21 days of WD, when compared to WW plants. Thus, R. sativus has shown greater tolerance to water deficits mainly due to the presence of very fine roots throughout the period of stress, when compared to C. abyssinica in which the fine roots predominated. creator: Luciana Minervina de Freitas Moura creator: Alan Carlos da Costa creator: Roberto Gomes Vital creator: Adinan Alves da Silva creator: Arthur de Almeida Rodrigues creator: Silvio Alencar Cândido-Sobrinho creator: Caroline Müller uri: https://doi.org/10.7717/peerj.13595 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 de Freitas Moura et al. title: A comparison of non-surgical methods for sexing young gopher tortoises (Gopherus polyphemus) link: https://peerj.com/articles/13599 last-modified: 2022-06-14 description: Many turtle species have temperature-dependent sex determination (TSD), raising the prospect that climate change could impact population dynamics by altering sex ratios. Understanding how climate change will affect populations of animals with TSD requires a reliable and minimally invasive method of identifying the sexes of young individuals. This determination is challenging in many turtles, which often lack conspicuous external sexual dimorphism until years after hatching. Here, we explore four alternatives for sexing three age classes of captive-reared young gopher tortoises (Gopherus polyphemus), a terrestrial turtle of conservation concern native to the southeastern United States: (1) naive testosterone levels, (2) testosterone levels following a follicle stimulating hormone (FSH) challenge, (3) linear morphological measurements, and (4) geometric morphometrics. Unlike some other turtle species, male and female neonatal gopher tortoises have overlapping naive testosterone concentration distributions, justifying more complicated methods. We found that sex of neonates (<7 days old) is best predicted by a “random forest” machine learning model with naive testosterone levels and morphological measurements (8% out-of-bag error). Sex of hatchlings (4–8 months old) was predicted with 11% error using a simple threshold on naive testosterone levels, or with 4% error using a simple threshold on post-FSH testosterone levels. Sex of juveniles (approximately 3.5 years old) was perfectly predicted using a simple threshold on naive testosterone levels. Sexing hatchlings at >4 months of age is the easiest and most reliable non-surgical method for sex identification. Given access to a rearing facility and equipment to perform hormone assays, these methods have the potential to supplant laparoscopic surgery as the method of choice for sexing young gopher tortoises. creator: Kevin J. Loope creator: David C. Rostal creator: M.A. Walden creator: Kevin T. Shoemaker creator: Elizabeth A. Hunter uri: https://doi.org/10.7717/peerj.13599 license: https://creativecommons.org/publicdomain/zero/1.0/ rights: title: Body mass index and postoperative mortality in patients undergoing coronary artery bypass graft surgery plus valve replacement: a retrospective cohort study link: https://peerj.com/articles/13601 last-modified: 2022-06-14 description: BackgroundThe relationship between body mass index (BMI) and postoperative mortality in patients who undergo coronary artery bypass graft (CABG) surgery plus valve replacement is uncertain. We aimed to investigate the association between body mass index (BMI) and postoperative mortality among patients who simultaneously underwent both CABG surgery plus valve replacement.MethodsWe retrospectively analyzed 1976 patients who underwent CABG surgery at our hospital between January 2017 and April 2021, including 202 patients who underwent valve replacement surgery during the same period. We analyzed the relationship between BMI and postoperative mortality. The relationship between BMI and postoperative mortality was assessed using smooth curve fitting and a Multiple logistic regression model.ResultsThe results of smoothing curve fitting showed that BMI and postoperative mortality had a non-linear relationship, and the resulting curve exhibited a two-stage change and a breakpoint. Postoperative mortality is higher in patients that have a body mass index above 25 kg/m2 compared to patients having a body mass index between 18 and 25 kg/m2.ConclusionsOur study found a non-linear relationship between BMI and postoperative mortality in patients undergoing CABG plus valve replacement after adjusting for potential confounders. The causal relationship between BMI and postoperative mortality still requires further investigations. creator: Chun Dai creator: Hongbo Xu creator: Tianshu Chu creator: Boyang Cao creator: Jianjun Ge uri: https://doi.org/10.7717/peerj.13601 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Dai et al. title: Assessing the size at maturity, spawning, and condition of the truncate soft-shell clam (Mya truncata) of southern Baffin Island, Nunavut, Canada link: https://peerj.com/articles/13231 last-modified: 2022-06-13 description: The truncate soft-shell clam Mya truncata is an important source of country food for Inuit communities across the territory of Nunavut, Canada. M. truncata also plays an important role in marine ecosystems, yet there is little understanding of their life history and condition in Canadian Arctic waters. To provide a foundation on which aspects of the life history and condition of M. truncata of Baffin Island can be monitored in the future with a changing climate and fishery development, this study estimated size at maturity and provides insights into the spawning cycle and weight-length condition indices of clams from inner Frobisher Bay and the north shore of the Hudson Strait. Male and female M. truncata exhibited similar lengths at 50% attainment of sexual maturity, 31 mm and 32 mm shell length (SL), respectively. Most (77%) of the sexually mature M. truncata collected from inner Frobisher Bay in late August and 35% of clams collected from the Hudson Strait in early September were in the ripe stage of gonadal development. These results lead us to suggest a spring spawning season and that M. truncata invest in gonadal development for the next year’s spawning during the late summer-early autumn ice-free season while phytoplankton concentrations are high. Dry bodyweight-SL relationships were used to show that M. truncata condition can differ significantly over small and large spatial scales based on plotted 95% confidence intervals. creator: Jessica M. Wood creator: Meghan Donovan creator: Scott M. Grant uri: https://doi.org/10.7717/peerj.13231 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Wood et al. title: Pollen transfer and patterns of reproductive success in pure and mixed populations of nectariferous Platanthera bifolia and P. chlorantha (Orchidaceae) link: https://peerj.com/articles/13362 last-modified: 2022-06-13 description: Plant species evolution is driven by many factors that have different roles in space and time. Using different field and laboratory methods, we studied reproductive patterns and their determinants in pure and mixed P. bifolia and P. chlorantha populations in different habitats. We also considered the probability of hybridisation between these two species and the role of intra-population processes in maintaining species integrity. Generally, we found a high level of reproductive success in both Platantherans. In both species, male (MRS) and female (FRS) reproductive success depended on floral display, and male reproductive success additionally on population structure. The flower traits were only weakly related to reproductive success. Moths’ assemblages varied spatially and temporally, and their diversity and numbers were correlated with MRS in the year, when their abundance was markedly lower. Analysis of patterns of pollen transfer showed that pollen was transported up to 25 m (average 8.2 ± 4.83 m) and showed gene exchange between these two Platanthera species. The germination level of both species was significantly lower than seed viability, although P. bifolia seed germinated with higher frequency than P. chlorantha seeds. We noted differences in viability and germination of seeds developed as an effect of experimental interspecies crossings and those developed from natural pollination. The presence of intermediate ecotypes together with observations of spontaneous interspecies crosses in the field and viability of seeds produced in interspecies crossing suggest that both pre- and postzygotic reproductive barriers are not complete and do not prevent hybrid production. creator: Emilia Brzosko creator: Krzysztof Frąckiel creator: Edyta Jermakowicz creator: Paweł Mirski creator: Beata Ostrowiecka creator: Izabela Tałałaj uri: https://doi.org/10.7717/peerj.13362 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Brzosko et al. title: Factors that influence Cape fur seal predation on Cape gannets at Lambert’s Bay, South Africa link: https://peerj.com/articles/13416 last-modified: 2022-06-13 description: Seabird populations experience predation that can impact their breeding density and breeding success. The Cape gannet Morus capensis is endemic to the Benguela upwelling ecosystem and is classified as Endangered by the IUCN. They are affected by several threats, including predation by the Cape fur seal Arctocephalus pusillus pusillus. Many fledglings succumb to predation during their maiden flight across waters around the island. To curb predation, the selective culling of individual predatory seals was implemented in 2014, 2015, and 2018. Our first study objective was to determine if selective culling of Cape fur seals significantly reduced predation probability on Cape gannets. We tested whether predation probability in 2014, 2015, and 2018 was affected by fish biomass, gannet fledgling numbers, and/or the presence/absence of selective culling. Our second objective was to determine what led to fluctuations in Cape fur seal predation on Cape gannet fledglings between 2007 and 2018. We tested whether fish biomass and the amount of Cape gannet fledglings in the water affected predation probability on the fledglings. Results indicated that selective culling reduced predation within years. We found that with both increased fledgling numbers and increased fish biomass, seal predation probability was reduced. This suggests that a sustainable way to promote the conservation of Cape gannets would be to increase food availability for both the Cape fur seals and Cape gannets. Our findings, collectively with the global trend of the declining Cape gannet population and their endemism, provide reasons advocating for the conservation of the food resources of both the Cape fur seal and the Cape gannet in the Benguela system. creator: Zanri Strydom creator: Lauren J. Waller creator: Mark Brown creator: Hervé Fritz creator: Kevin Shaw creator: Jan A. Venter uri: https://doi.org/10.7717/peerj.13416 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Strydom et al.