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1.
Phys Sportsmed ; : 1-5, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38975984

RESUMO

Surfer's neurapraxia is a rare surfing injury of the saphenous nerve secondary to persistent compression of the saphenous nerve along the medial thigh by the surfboard when paddling prone and while sitting upright on the board waiting for a wave. Symptoms may be nonspecific and consist of pain in the medial thigh with or without radiation along the saphenous nerve distribution (medial leg, medial ankle, medial arch of the foot). The saphenous nerve tension test can be utilized to reproduce the symptoms of surfer's neurapraxia. Treatment consists of conservative management while refractory cases may benefit from injection with local anesthetic. The authors propose the Obana Plan (WATER) for prevention of surfer's neurapraxia, consisting of Wetsuits, Abduction, Timing, Exercise, and Rest. Overall, surfer's neurapraxia is a benign condition that can be prevented and managed conservatively.

2.
J Soc Distress Homeless ; 33(1): 186-197, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38911355

RESUMO

Background: Sexual minority youth are at more than twice the risk of experiencing homelessness than their peers and both sexual minority youth and youth experiencing homelessness have disproportionate risk for mental health disorder symptoms. Couch-surfing is a common form of homelessness experienced by youth, but research on the relationship between couch-surfing and mental health outcomes, especially among sexual minority adolescents (SMA), is limited. Methods: Utilizing a sample of 2,558 SMA (14-17 years old) recruited via social media and respondent-driven sampling, this study explores the relationship between different forms of homelessness (exclusive couch-surfing vs. multiple types of homelessness) and symptoms of depression, anxiety, suicidal ideation, and suicide attempt. Results: Nearly 21% of participants experienced any homelessness in their lifetime, with 14% reporting exclusive couch-surfing. All forms of homelessness were associated with large increases in symptoms of anxiety, depression, suicidal ideation and suicide attempt. Conclusion: Homelessness - primarily couch-surfing - is a common experience for SMA in this sample. All forms of homelessness - including exclusive couch-surfing - were associated with large increases in depression, anxiety, suicidal ideation, and suicide attempt, emphasizing the importance of services that are available to couch-surfing young people and responsive to the needs of sexual minority adolescents.

3.
Soins Psychiatr ; 45(352): 32-35, 2024.
Artigo em Francês | MEDLINE | ID: mdl-38719358

RESUMO

Imagine a dream where ocean waves become allies for the caregiver. This vision took shape in a project begun in 2020 at the Clinique de l'Odet, the addictology department of the public mental health establishment in South Finistère: surf therapy as a tool for addictology care, the ocean as an ecological framework for rehabilitation. In this exceptional adventure, the dream of a care team to support patients' recovery through surfing has become a reality, where every wave is a step towards freedom; every take-off a victory on the road to recovery.


Assuntos
Transtornos Relacionados ao Uso de Substâncias , Humanos , Transtornos Relacionados ao Uso de Substâncias/enfermagem , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Transtornos Relacionados ao Uso de Substâncias/psicologia , França , Negociação/psicologia
5.
Sci Total Environ ; 934: 173260, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38761933

RESUMO

The LIFE SURFING Project was carried out at the Bailin Landfill in Sabiñánigo, Spain (2020-2022), applying Surfactant Enhanced Aquifer Remediation (SEAR) and In Situ Chemical Oxidation (S-ISCO) in a 60-meter test cell beneath the old landfill, to remediate a contaminated aquifer with dense non-aqueous phase liquid (DNAPL) from nearby lindane production. The project overcame traditional extraction limitations, successfully preventing groundwater pollution from reaching the river. In spring 2022, two SEAR interventions involved the injection of 9.3 m3 (SEAR-1) and 6 m3 (SEAR-2) of aqueous solutions containing 20 g/L of the non-ionic surfactant E-Mulse 3®, with bromide (around 150 mg/L) serving as a conservative tracer. 7.1 and 6.0 m3 were extracted in SEAR-1 and SEAR-2, respectively, recovered 60-70 % of the injected bromide and 30-40 % of the surfactant, confirming surfactant adsorption by the soil. Approximately 130 kg of DNAPL were removed, with over 90 % mobilized and 10 % solubilized. A surfactant-to-DNAPL recovery mass ratio of 2.6 was obtained, a successful value for a fractured aquifer. In September 2022, the S-ISCO phase entailed injecting 22 m3 of a solution containing persulfate (40 g/L), E-Mulse 3® (4 g/L), and NaOH (8.75 g/L) in pulses over 48 h, oxidizing around 20 kg of DNAPL and ensuring low toxicity levels after that. Preceding the SEAR and S-ISCO trials, 2020 and 2021 were dedicated to detailed groundwater flow characterizations, including hydrological and tracer studies. These preliminary investigations allowed the design of a barrier zone between 317 and 557 m from the test cell and the river, situated 900 m away. This zone, integrating alkali dosing, aeration, vapor extraction, and oxidant injection, effectively prevented the escape of fluids to the river. Neither surfactants nor contaminants were detected in river waters post-treatment. The absence of residual phase in test cell wells and reduction of chlorinated compound levels in groundwater were noticed till one year after S-ISCO.

6.
Ecol Evol ; 14(4): e11212, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38584770

RESUMO

Reconstructing biological invasions from historical sources can provide insights into how they occur but are difficult to do when invasions are poorly documented. Genetic signatures left by invaders can also offer insights into invasion routes, points of origin and general biology but often present conclusions that are contradictory to expectations. Here, we test the ability of continental-wide microsatellite genotype data from 29 loci and 3122 samples to reconstruct the well-documented invasion of red foxes Vulpes vulpes from the United Kingdom into Australia over 150 years ago, an invasion that has led to the extinction of many native species. Our analysis reveals several key signals of invasion evident in Australian foxes. They display lower levels of diversity than foxes sampled from the UK, exhibit clines in diversity from the point of introduction (south-east Australia) to the edge of their range, and show strong evidence of allele surfing in westerly and north-easterly directions. These characteristics are consistent with a single point of origin followed by rapid expansion in westerly and north-easterly directions as suggested by historical records. We also find little genetic structure in foxes across Australia with only the vast Nullarbor Plains and Great Victoria Desert region presenting a detectable barrier to their dispersal. As such, no mainland region within the current range of foxes can be considered genetically isolated and therefore appropriate for localised eradication efforts. Overall, our analyses demonstrate the ability of comprehensive population genetic studies to reconstruct invasion histories even after more than 80 years since colonisation was stabilised.

7.
Orthop J Sports Med ; 12(4): 23259671241237289, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38617886

RESUMO

Background: Surfing is an increasingly popular sport with a high propensity for both traumatic and atraumatic injuries. Purpose: To analyze the trends, etiologies, and diagnoses of lower extremity orthopaedic-related surfing injuries presenting to United States (US) emergency departments (EDs) within a 21-year study period. Study Design: Descriptive epidemiology study. Methods: The National Electronic Injury Surveillance System database was queried for data on lower extremity surfing injuries presenting to US EDs from January 1 to December 31, 2022. Data collected included year, injury mechanism, injury location, diagnosis, and disposition. The raw data were used to calculate national estimates (NEs) based on each hospital's assigned statistical sample weight. Linear regressions were performed to analyze annual trends. Results: A total of 776 lower extremity surfing injuries were included (NE = 49,218 injuries). The mean age of the patients was 29.4 ± 13.6 years. The most common injured areas were the foot (NE = 17,411; 35.4%), lower leg (NE = 8673, 17.6%), and knee (NE = 8139; 16.5%). The most common mechanism of injury was impact with board (NE = 17,144; 34.8%), and the most common fracture locations were the lower leg (NE = 1195; 29.5%), ankle (NE = 1594; 24.5%), and foot (NE = 1495; 23.0%). There were statistically significant decreases in weighted estimates for lower extremity surfing injuries by 108 per year (P < .001), for lacerations by 76 per year (P < .001), and for sprains by 18 per year (P = .01). Impact-with-board injuries decreased by 59 injuries per year (P < .001) and constituted 63.5% of lacerations and 12.1% of fractures. Only 3.9% of patients were admitted for hospitalization. Conclusion: There was a decreasing trend in lower extremity surfing injuries presenting to US EDs during the 21-year study period.

8.
Aust N Z J Public Health ; 48(3): 100116, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38413291

RESUMO

OBJECTIVE: To explore the views of surfers on investment in shark management compared to other coastal public health issues. METHODS: We examined the responses of 672 New South Wales (NSW) resident surfers to the Global Surfer Survey, which collected demographic information and asked surfers about which topics they believe additional funding should be devoted to. RESULTS: Half of surfers in NSW (50%) are worried about sharks while surfing only a very small proportion (16%) are supportive of additional funding for shark detection and management programs, with most being in favour of funding directed at ocean cleanliness (40%) and drowning prevention (29%). CONCLUSIONS: Findings indicate surfers are more supportive of investment in ocean cleanliness and drowning prevention measures, as compared to shark mitigation. IMPLICATIONS FOR PUBLIC HEALTH: Ocean users in general face a significantly greater risk (48 times) of drowning than shark bites. Given the relative public health burden of the two issues, is the significant financial investment in shark mitigation worth it?


Assuntos
Afogamento , Saúde Pública , Tubarões , Humanos , Animais , Masculino , Feminino , New South Wales , Adulto , Afogamento/prevenção & controle , Pessoa de Meia-Idade , Inquéritos e Questionários , Mordeduras e Picadas , Adulto Jovem , Oceanos e Mares , Adolescente
9.
Wilderness Environ Med ; 35(1): 74-77, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38379481

RESUMO

Hand injuries from surfing tend to be severe and require medical attention. Follow-up of a surfing injury is difficult because many patients are visiting and go home after treatment. We report a case of a surfing hand injury sustained abroad, which was treated upon the patient's return, allowing for follow-up. The mechanism of injury was traction and torsion from the surfboard leash while surfing. The patient was initially treated for nailbed injury but presented later back home after persistent pain, for which an unstable distal phalanx fracture in their right ring finger was found by x-ray. This was surgically reduced with K-wire insertion and nailbed repair. Postoperatively, the injured finger was kept in a splint, and the patient had physiotherapy. Pain was significantly reduced, and the patient regained sufficient function. Considering a fracture as a differential for finger injury caused by the surfboard leash may prevent management delays. Injury may be prevented through education and redesign of the surfboard leash.


Assuntos
Traumatismos em Atletas , Traumatismos dos Dedos , Fraturas Ósseas , Esportes , Humanos , Fraturas Ósseas/cirurgia , Traumatismos em Atletas/etiologia , Traumatismos dos Dedos/etiologia , Traumatismos dos Dedos/cirurgia , Dor
10.
Am Nat ; 203(3): 382-392, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38358811

RESUMO

AbstractModels of range expansion have independently explored fitness consequences of life history trait evolution and increased rates of genetic drift-or "allele surfing"-during spatial spread, but no previous model has examined the interactions between these two processes. Here, using spatially explicit simulations, we explore an ecologically complex range expansion scenario that combines density-dependent selection with allele surfing to asses the genetic and fitness consequences of density-dependent selection on the evolution of life history traits. We demonstrate that density-dependent selection on the range edge acts differently depending on the life history trait and can either diminish or enhance allele surfing. Specifically, we show that selection at the range edge is always weaker at sites affecting competitive ability (K-selected traits) than at sites affecting birth rate (r-selected traits). We then link differences in the frequency of deleterious mutations to differences in the efficacy of selection and rate of mutation accumulation across distinct life history traits. Finally, we demonstrate that the observed fitness consequences of allele surfing depend on the population density in which expansion load is measured. Our work highlights the complex relationship between ecology and expressed genetic load, which will be important to consider when interpreting both experimental and field studies of range expansion.


Assuntos
Características de História de Vida , Evolução Biológica , Mutação , Deriva Genética , Ecologia , Seleção Genética , Modelos Genéticos
11.
Mol Ecol ; 33(5): e17269, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38234254

RESUMO

Environmental conditions vary greatly across large geographic ranges, and yet certain species inhabit entire continents. In such species, genomic sequencing can inform our understanding of colonization history and the impact of selection on the genome as populations experience diverse local environments. As ectothermic vertebrates are among the most vulnerable to environmental change, it is critical to understand the contributions of local adaptation to population survival. Widespread ectotherms offer an opportunity to explore how species can successfully inhabit such differing environments and how future climatic shifts will impact species' survival. In this study, we investigated the widespread painted turtle (Chrysemys picta) to assess population genomic structure, demographic history, and genomic signatures of selection in the western extent of the range. We found support for a substantial role of serial founder effects in shaping population genomic structure: demographic analysis and runs of homozygosity were consistent with bottlenecks of increasing severity from eastern to western populations during and following the Last Glacial Maximum, and edge populations were more strongly diverged and had less genetic diversity than those from the centre of the range. We also detected outlier loci, but allelic patterns in many loci could be explained by either genetic surfing or selection. While range expansion complicates the identification of loci under selection, we provide candidates for future study of local adaptation in a long-lived, widespread ectotherm that faces an uncertain future as the global climate continues to rapidly change.


Assuntos
Genoma , Genômica , Animais , Vertebrados/genética , Demografia , Seleção Genética
12.
Eur Arch Otorhinolaryngol ; 281(2): 573-578, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37777626

RESUMO

OBJECTIVE: External auditive exostosis (EAE), known as surfer's ear, is a temporal bone outgrowth resulting from ear exposure to cold air and water. This review aims to shed light on the prevalence of EAE among worldwide surfers. METHODS: By a thorough retrieval of the PubMed, we found all original investigations performed on EAE among suffers. The retrieval time was from the construction of the database to December 2022. Agency for Healthcare Research and Quality (AHRQ) methodology checklist for assessing the quality of cross-sectional/prevalence study was performed. RESULTS: 19 articles were selected involving 2997 surfers on whom 2032 presented EAE. The prevalence of EAE was ranged from 53 to 90% with a mean at 67.8%. 3 investigations were performed from USA, five from UK and Ireland, five from Australia and New Zealand and six from Japan and Europe. CONCLUSION: Cold water exposure, combined with wind and prolonged surfing activity, contributes to the development of EAE. Symptoms range from mild discomfort to hearing loss and recurrent infections. Preventive measures, such as raising awareness and promoting the use of ear protection, are crucial. Further research is needed to improve prevention strategies and understand the underlying mechanisms of EAE.


Assuntos
Exostose , Esportes , Humanos , Estudos Transversais , Meato Acústico Externo , Exostose/epidemiologia , Exostose/prevenção & controle , Água
13.
Plant J ; 117(2): 432-448, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37850375

RESUMO

Coastal forests, such as mangroves, protect much of the tropical and subtropical coasts. Long-distance dispersal via sea-surfing propagules is essential for coastal plants, but the genomic and molecular basis of sea-surfing plant propagule evolution remains unclear. Heritiera fomes and Heritiera littoralis are two coastal plants with typical buoyant fruits. We de novo sequenced and assembled their high-quality genomes. Our phylogenomic analysis indicates H. littoralis and H. fomes originated (at ~6.08 Mya) just before the start of Quaternary sea-level fluctuations. Whole-genome duplication occurred earlier, permitting gene copy gains in the two species. Many of the expanded gene families are involved in lignin and flavonoid biosynthesis, likely contributing to buoyant fruit emergence. It is repeatedly revealed that one duplicated copy to be under positive selection while the other is not. By examining H. littoralis fruits at three different developmental stages, we found that gene expression levels remain stable from young to intermediate. However, ~1000 genes are up-regulated and ~ 3000 genes are down-regulated as moving to mature. Particularly in fruit epicarps, the upregulation of WRKY12 and E2Fc likely constrains the production of p-Coumaroyl-CoA, the key internal substrate for lignin biosynthesis. Hence, to increase fruit impermeability, methylated lignin biosynthesis is shut down by down-regulating the genes CCoAOMT, F5H, COMT, and CSE, while unmethylated lignins are preferentially produced by upregulating CAD and CCR. Similarly, cutin polymers and cuticular waxes accumulate with high levels before maturation in epicarps. Overall, our genome assemblies and analyses uncovered the genomic evolution and temporal transcriptional regulation of sea-surfing propagule.


Assuntos
Lignina , Plantas , Lignina/metabolismo , Plantas/metabolismo , Frutas/genética , Frutas/metabolismo , Filogenia , Regulação da Expressão Gênica de Plantas/genética
14.
Hawaii J Health Soc Welf ; 82(12): 283-288, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38093760

RESUMO

Concussions are caused by physical trauma to the head, face, or neck and can be sustained while surfing, increasing the risk of drowning. The purpose of this pilot study was to establish a preliminary assessment of concussion knowledge in a group of adult recreational surfers. Using the standardized Concussion Knowledge Index, an anonymous survey was conducted with 55 surfers. The Concussion Knowledge Index and similar statistical measures were used in a previous study of adult soccer players in England. Data from these 2 groups were compared. The preliminary data suggests that the group of adult surfers demonstrate more concussion knowledge than the group of adult soccer players. Further study into surfers' knowledge of concussion with a larger sample size could increase the clinical utility and generalizability of this study.


Assuntos
Traumatismos em Atletas , Concussão Encefálica , Futebol , Adulto , Humanos , Futebol/lesões , Projetos Piloto , Concussão Encefálica/etiologia , Concussão Encefálica/complicações , Atletas
15.
Artigo em Russo | MEDLINE | ID: mdl-37966445

RESUMO

OBJECTIVE: To evaluate the modifiable daily behavior patterns associated with increased anxiety indicators in the general population in response to the COVID-19 pandemic. MATERIAL AND METHODS: The study examined the characteristics of the Russian population (n=7777) of the international multicenter project COMET-G. In particular, variables were targeted to describe deviations in the behavior of adults during the period of application of measures of social isolation in connection with the pandemic, and revealing a relationship with the total score on the Spielberger State Anxiety Scale (STAI-S). Among these variables, experts selected those that could potentially be subject to change in the short term, that is, act as manageable or modifiable risk factors for the development of anxiety. The selected variables were analyzed in a statistical PLS-model to identify indicators that make the most significant contribution to the increase in the total anxiety score. RESULTS: Our statistical model explained 48.4% of the variability in the STAI-S anxiety total scores related to changes in daily life habits. In particular, doom-scrolling/doom-surfing about the spread of the virus and the COVID-19 pandemic, changes in sleep patterns and usual daily life activities due to social isolation measures presented as factors significantly contributing to the increase of state anxiety. CONCLUSION: Given the manageable or modifiable risk factors that we have identified, public awareness and therapeutic recommendations, pointing to the need to (I) control the amount of time spent in the internet and monitor their internet-based content consumption, (II) regulate sleep-wake patterns, (III) maintain daily habits and household activities, may reduce the likelihood of developing anxiety disorders in the context of the impact of a global chronic stress due to the COVID-19 pandemic and associated social isolation measures.


Assuntos
COVID-19 , Pandemias , Adulto , Humanos , COVID-19/epidemiologia , Ansiedade/epidemiologia , Transtornos de Ansiedade , Fatores de Risco , Sono
16.
bioRxiv ; 2023 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-37905020

RESUMO

Despite newly formed polyploids being subjected to myriad fitness consequences, the relative prevalence of polyploidy both contemporarily and in ancestral branches of the tree of life suggests alternative advantages that outweigh these consequences. One proposed advantage is that polyploids have an elevated adaptive potential that enables them to colonize novel habitats such as previously glaciated areas. However, previous research conducted in diploids suggests that range expansion comes with a fitness cost as deleterious mutations may fix rapidly on the expansion front. Here, we interrogate the potential consequences of expansion in polyploids by conducting spatially explicit forward-in-time simulations of autopolyploids, allopolyploids, and diploids to investigate how ploidy and inheritance patterns impact the relative ability of polyploids to expand their range. We show that under realistic dominance models, autopolyploids suffer greater fitness reductions than diploids as a result of range expansion due to the fixation of increased mutational load that is masked in the range core. Alternatively, the disomic inheritance of allopolyploids provides a shield to this fixation resulting in minimal fitness consequences under an empirically estimated DFE. In light of this advantage provided by disomy, we investigate how range expansion may influence cytogenetic diploidization through the reversion to disomy in autotetraploids. We show that under both a model of where the mode of inheritance is determined by a small number of loci and a model where inheritance is regulated by chromosomal similarity, disomy evolves more rapidly on the expansion front than in the range core, and that this dynamic inheritance model has additional effects on fitness. Together our results point to a complex interaction between dominance, ploidy, inheritance, and recombination on fitness as a population spreads across a geographic range.

17.
Hawaii J Health Soc Welf ; 82(10): 232-239, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37808265

RESUMO

Surfing is a globally popular recreational sport with limited epidemiologic data. Currently, there is a paucity of literature regarding injury profiles and mechanisms of orthopaedic-related injuries. This study analyzed trends, etiologies, and diagnoses of upper extremity orthopaedic-related surfing injuries presenting to United States (US) emergency departments. The National Electronic Injury Surveillance System database was accessed to query upper extremity surfing-related injuries presenting to US emergency departments from January 1, 2002 to December 31, 2021. Data were analyzed for year, body part, mechanism of injury, diagnosis, and disposition. National estimates were calculated based on the assigned statistical sample weight of each hospital. A total of 33 323 surfing-related injuries were included. The most common upper extremity body parts involved 15 169 shoulders (45.5%), 4220 fingers (12.7%), and 3753 hands (11.3%). The most common identifiable mechanisms of injuries were 7474 board-to-body (22.4%), 4188 impact with sand (12.6%), and 2639 impact with water (7.9%). Overuse constituted 7.2% of overall upper extremity injuries but 40% of strains. Only 2.2% of injuries required hospital admission. Between 2002 and 2021, there was a decreasing annual trend in upper extremity surfing-related injuries (P=.01). The decreasing trend in emergency department visits may be due to urgent care utilization and training for surfers and lifeguards to manage these injuries on-site, as the majority were minor given the small proportion requiring hospital admission. Chronic stress on rotator cuff and peri-scapular musculature while paddling in the prone position likely contributed to the large proportion of overuse injury.


Assuntos
Traumatismos do Braço , Traumatismos em Atletas , Humanos , Estados Unidos/epidemiologia , Traumatismos em Atletas/epidemiologia , Traumatismos do Braço/complicações , Serviço Hospitalar de Emergência , Extremidade Superior/lesões , Hospitalização
18.
Nutr Health ; : 2601060231204927, 2023 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-37774739

RESUMO

BACKGROUND: Surfing is a rapidly growing sport and recreational activity. The previously reported, intermittent high-intensity energetics of surfing place athletes and recreational participants at risk of low energy availability (LEA). AIM: As such, this pioneering study aims to be the first to investigate LEA risk and the second to investigate dietary intake in surfers. METHODS: Twenty-one intermediate and advanced surfers (female - 5, male - 16) were recruited to complete an online self-administered questionnaire and 4 consecutive 24-hour food logs to establish LEA risk and asses dietary intake. The Low Energy Availability in Female Questionnaire and Eating Disorder Examination Questionnaire were used to identify at-risk individuals in females and males, respectively, with respective cut-off's of ≥8 and ≥2.3. RESULTS: Fifty-seven percent were classed as at-risk of LEA (50% and 80% in males and females, respectively). No significant relationship of competitive status, surfing ability and body mass index on risk classification was found. However, a non-significant medium effect of age was observed (p = 0.338, R = 0.549). And 77% of the 70 total analysed food records showed inadequate carbohydrate (CHO) consumption. CONCLUSION: In summary, an alarmingly high portion of surfers are at risk of LEA and dietary inadequacy. Future studies should confirm whether surfing organisations need to intervene, by addressing limitations of the present study including a small sample, which was heavily biased away from female and high-level competitors.

19.
Biomimetics (Basel) ; 8(5)2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37754191

RESUMO

From insects to arachnids to bacteria, the surfaces of lakes and ponds are teaming with life. Many modes of locomotion are employed by these organisms to navigate along the air-water interface, including the use of lipid-laden excretions that can locally change the surface tension of the water and induce a Marangoni flow. In this paper, we improved the speed and maneuverability of a miniature remote-controlled robot that mimics insect locomotion using an onboard tank of isopropyl alcohol and a series of servomotors to control both the rate and location of alcohol release to both propel and steer the robot across the water. Here, we studied the effect of a series of design changes to the foam rubber footpads, which float the robot and are integral in efficiently converting the alcohol-induced surface tension gradients into propulsive forces and effective maneuvering. Two designs were studied: a two-footpad design and a single-footpad design. In the case of two footpads, the gap between the two footpads was varied to investigate its impact on straight-line speed, propulsion efficiency, and maneuverability. An optimal design was found with a small but finite gap between the two pads of 7.5 mm. In the second design, a single footpad without a central gap was studied. This footpad had a rectangular cut-out in the rear to capture the alcohol. Footpads with wider and shallower cut-outs were found to optimize efficiency. This observation was reinforced by the predictions of a simple theoretical mechanical model. Overall, the optimized single-footpad robot outperformed the two-footpad robot, producing a 30% improvement in speed and a 400% improvement in maneuverability.

20.
Microbiology (Reading) ; 169(8)2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37561015

RESUMO

Studies of microbial evolution, especially in applied contexts, have focused on the role of selection in shaping predictable, adaptive responses to the environment. However, chance events - the appearance of novel genetic variants and their establishment, i.e. outgrowth from a single cell to a sizeable population - also play critical initiating roles in adaptation. Stochasticity in establishment has received little attention in microbiology, potentially due to lack of awareness as well as practical challenges in quantification. However, methods for high-replicate culturing, mutant labelling and detection, and statistical inference now make it feasible to experimentally quantify the establishment probability of specific adaptive genotypes. I review methods that have emerged over the past decade, including experimental design and mathematical formulas to estimate establishment probability from data. Quantifying establishment in further biological settings and comparing empirical estimates to theoretical predictions represent exciting future directions. More broadly, recognition that adaptive genotypes may be stochastically lost while rare is significant both for interpreting common lab assays and for designing interventions to promote or inhibit microbial evolution.


Assuntos
Evolução Biológica , Mutação
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