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Studies in veterans have yet to examine interconnections between homelessness, financial debt, and suicidal ideation. We analyzed data from a nationally-representative study conducted in 2021 of low-income U.S. veterans (N = 1,004). Analyses revealed veterans who were younger, male, had a history of criminal arrests, met criteria for posttraumatic stress disorder (PTSD), reported greater loneliness, or had both a history of homelessness and higher debt were more likely to endorse suicidal ideation. We found an interaction between a history of homelessness and current debt: 40% of veterans with both past homelessness and higher debt reported suicidal ideation, whereas only 10% of veterans with either past homelessness or higher debt reported suicidal ideation. As past homelessness and current debt interacted to increase the odds of suicidal ideation in a national sample of veterans, these results inform policy and clinical decision-making for suicide prevention and in programs serving veterans experiencing homelessness.
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INTRODUCTION: aging is associated with loss of balance, with falls being the leading cause of death among elderly in the United States. Gaze stabilization exercises (GSE) improve balance control in vestibular populations and could be useful to prevent falls in healthy individuals. However, the extent to which aging affects head kinematics in GSE is unknown. METHODS: forty-eight young (n=25, 24 ± 6 years, 60% female) and older (n=23, 66 ± 5 years, 56% female) adults completed six 30-second GSE. Participants were asked to maintain gaze fixation on a stationary target while continuously performing head movements in pitch (e.g., vertical) and yaw (e.g., horizontal) directions. The visual target was placed on the wall 1m or 2m away, or hand-held at arm's length. Head kinematics were recorded with an inertial measurement unit placed on the back of the participants' head. RESULTS: older adults took significantly more time (e.g., delay) to complete cycles of head rotation compared to young participants across all GSE. Such delay was further increased during pitch head rotation while fixating gaze of the 1m target. The range of velocity (ROV) of head rotation, however, was equivalent between groups in all GSE. CONCLUSION: aging leads to the maintenance of head cycle ROV at the expense of delayed cycles of head rotation, suggesting an age-dependent prioritization strategy (e.g., adapt duration first vs range second) during continuous head movements. The distance of the visual target and head movement direction influenced elderly performance and should be considered when prescribing GSE to older populations.
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OBJECTIVES: To assist with clinical decision-making, evidence syntheses are needed to demonstrate the efficacy of available interventions, and examine the intervention components and dosage parameters. This systematic review and meta-analysis describes the efficacy, components and dosage of interventions targeting upright balance control, balance confidence and/or falls in adults with motor incomplete spinal cord injuries/diseases (SCI/D). DATA SOURCES: A search strategy following the PICO framework was developed. Six databases were searched: APA PsychInfo, CINAHL, Embase, Emcare Nursing, Web of Science CC, and Medline. STUDY SELECTION: Title, abstract and full-text screening were conducted by two researchers independently. Inclusion criteria included: 1) adults with chronic, motor-incomplete SCI/D; 2) physical intervention targeting upright postural control; and 3) clinical and/or biomechanical measures of upright balance control and/or balance confidence and/or documentation of falls. DATA EXTRACTION: Participant characteristics, balance intervention details, adverse events and study results were extracted. The Downs and Black Checklist assessed methodological quality. Meta-analyses on pre-post intervention outcomes and a meta-regression of dosage were completed. The GRADE approach was used to evaluate the quality of the evidence. DATA SYNTHESIS: The search returned 1,664 unique studies; 26 were included. Methodological quality was moderate to good. Participants were 500 individuals with SCI/D, aged 18-74 years (males: femalesâ¯=â¯2.4:1). Minor adverse events were reported in eight studies (e.g. muscle soreness, fatigue). Walking interventions and upright balance training with visual feedback had clinically meaningful and significant pooled effects on improving standing balance control. Only walking interventions had a significant pooled effect on improving balance confidence. There were no significant findings on dosage response. Few studies evaluated the effects of balance interventions on the occurrence of falls. CONCLUSIONS: Walking interventions and upright balance training with visual feedback had greater effects on upright balance control than conventional physiotherapy; however, the quality of the evidence was very low.
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BACKGROUND: Exoskeletons are increasingly applied during overground gait and balance rehabilitation following neurological impairment, although optimal parameters for specific indications are yet to be established. OBJECTIVE: This systematic review aimed to identify dose and dosage of exoskeleton-based therapy protocols for overground locomotor training in spinal cord injury/disease. METHODS: A systematic review was conducted in accordance with the Preferred Reporting Items Systematic Reviews and Meta-Analyses guidelines. A literature search was performed using the CINAHL Complete, Embase, Emcare Nursing, Medline ALL, and Web of Science databases. Studies in adults with subacute and/or chronic spinal cord injury/disease were included if they reported (1) dose (e.g., single session duration and total number of sessions) and dosage (e.g., frequency of sessions/week and total duration of intervention) parameters, and (2) at least one gait and/or balance outcome measure. RESULTS: Of 2,108 studies identified, after removing duplicates and filtering for inclusion, 19 were selected and dose, dosage and efficacy were abstracted. Data revealed a great heterogeneity in dose, dosage, and indications, with overall recommendation of 60-min sessions delivered 3 times a week, for 9 weeks in 27 sessions. Specific protocols were also identified for functional restoration (60-min, 3 times a week, for 8 weeks/24 sessions) and cardiorespiratory rehabilitation (60-min, 3 times a week, for 12 weeks/36 sessions). CONCLUSION: This review provides evidence-based best practice recommendations for overground exoskeleton training among individuals with spinal cord injury/disease based on individual therapeutic goals - functional restoration or cardiorespiratory rehabilitation. There is a need for structured exoskeleton clinical translation studies based on standardized methods and common therapeutic outcomes.
Subject(s)
Exercise Therapy , Exoskeleton Device , Postural Balance , Spinal Cord Injuries , Spinal Cord Injuries/rehabilitation , Humans , Postural Balance/physiology , Exercise Therapy/methods , Exercise Therapy/instrumentation , Gait/physiology , Gait Disorders, Neurologic/rehabilitation , Gait Disorders, Neurologic/etiologyABSTRACT
OBJECTIVE: Considering that diagnostic decisions about mTBI are often predicated on clinical symptom criteria, it is imperative to determine which initial presentation features of mTBI have prognostic significance for identifying those at high risk for long-term functional impairment. SETTING: Zoom interview Participants: Male, former NCAA Division I, and professional-level National Football League (NFL) athletes (n = 177) between the ages of 27 and 85 (M = 54.1, SD = 14.7). DESIGN: Cross-sectional case-control. Main Measures: History of mild TBI, history of loss of consciousness (LOC), depression symptoms, insomnia, neurobehavioral symptoms. RESULTS: Number of mTBI exposures did not predict neurobehavioral symptoms (B = 0.21, SE = 0.18, p = 0.23), but number of mTBI + LOC events did (B = 2.27, SE = 0.64, p = <.001). Further analysis revealed that the number of mTBI + LOC events predicted neurobehavioral symptoms indirectly through both depression (B = 0.85, 95% CI = [0.27, 1.52) and insomnia (B = 0.81, 95% CI = [0.3, 1.4]). Further, the direct effect of mTBI + LOC events on neurobehavioral symptoms became non-significant when depression and insomnia were added to the model (B = 0.78, SE = 0.45, p = 0.08). CONCLUSIONS: Findings support LOC at time of injury as an important predictor of long-term outcomes. Additionally, results suggest depression and insomnia as potential mediators in the association between mTBI + LOC and neurobehavioral symptoms. These findings provide justification for early depression and insomnia symptom monitoring following mTBI + LOC.
Subject(s)
Athletes , Depression , Football , Sleep Initiation and Maintenance Disorders , Unconsciousness , Humans , Male , Sleep Initiation and Maintenance Disorders/etiology , Sleep Initiation and Maintenance Disorders/psychology , Football/injuries , Adult , Athletes/psychology , Cross-Sectional Studies , Middle Aged , Depression/etiology , Case-Control Studies , Aged , Unconsciousness/etiology , Aged, 80 and over , Athletic Injuries/complications , Athletic Injuries/psychology , Brain Concussion/complications , Brain Concussion/psychology , Brain Concussion/diagnosis , UniversitiesABSTRACT
Context: Digital contact tracing uses automated systems and location technology embedded on smartphone software for efficient identification of individuals exposed to COVID-19. Such systems are only effective with high compliance, yet compliance is mediated by public trust in the system. This work explored the perception of individual's trust and expectation of the broader Test and Trace system in the United Kingdom (UK) with the upcoming release of the National Health Service's (NHS) COVID-19 app as a case example. Methods: Twelve adults underwent online semi-structured interviews in August 2020, prior to public availability of the COVID-19 app. Pragmatic reflexive thematic analysis was applied inductively to explore common themes between participants, using an organic and recursive process (Braun & Clarke, 2019). Results: Themes highlighted features of the technology that would be perceived to be trustworthy (Theme 1), and concerns relating to i) whether users would comply with a T&T system (Theme 2) and ii) how a T&T system would handle user's personal data (Theme 3). Two further themes built on aspects of automation within a T&T system and its impact on trust (Theme 4) and how the media altered perceptions of the T&T system (Theme 5). Conclusions: Participants outlined the need for different user requirements that could be built into the NHS COVID-19 app that would support increased adherence. Concurrently, participants raised questions surrounding personal data and privacy of their data, plus the level of automated versus manual tasks, which impacted perception of trust in the app and wider system. Additionally, themes highlighted that T&T systems do not happen within a vacuum, but within a pre-existing environment influenced by variables such as the media and perception of other's compliance to T&T. Implications: Since it's roll-out, controversies surrounding the UK T&T system include concerns about privacy, stigma and uptake. Considering the current piece of work, which anticipated similar concerns prior to public access to COVID-19 app, engaging with the public may have been an important step in improving the perception and compliance with the app. Principles fundamental to patient and public involvement (PPI) and Responsible Research and Innovation (RRI) such as the inclusion of the public in the early development of research and aligning the outcomes of research and innovation with broader societal values and expectations would have been well-applied to this system and should be applied to future autonomous systems requiring high public uptake.
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Exposure to toxins-such as heavy metals and air pollution-can result in poor health and wellbeing. Recent scientific and media attention has highlighted negative health outcomes associated with toxic exposures for U.S. military personnel deployed overseas. Despite established health risks, less empirical work has examined whether deployment-related toxic exposures are associated with declines in mental and physical health after leaving military service, particularly among the most recent cohort of veterans deployed after September 11, 2001. Using data from 659 U.S. veterans in the VISN 6 MIRECC Post-Deployment Mental Health Study, we tested whether self-reported toxic exposures were associated with poorer mental and physical health. At baseline, veterans who reported more toxic exposures also reported more mental health, ß = 0.14, 95% CI [0.04, 0.23], p = 0.004, and physical health symptoms, ß = 0.21, 95% CI [0.11, 0.30], p < 0.001. Over the next ten years, veterans reporting more toxic exposures also had greater increases in mental health symptoms, ß = 0.23, 95% CI [0.15, 0.31], p < 0.001, physical health symptoms, ß = 0.22, 95% CI [0.14, 0.30], p < 0.001, and chronic disease diagnoses, ß = 0.15, 95% CI [0.07, 0.23], p < 0.001. These associations accounted for demographic and military covariates, including combat exposure. Our findings suggest that toxic exposures are associated with worsening mental and physical health after military service, and this recent cohort of veterans will have increased need for mental health and medical care as they age into midlife and older age.
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Self Report , Veterans , Humans , Male , Veterans/statistics & numerical data , Female , Adult , United States/epidemiology , Middle Aged , Military Personnel/statistics & numerical data , Health Status , Military Deployment/statistics & numerical data , September 11 Terrorist Attacks , Mental HealthABSTRACT
The difference in fleece type is the distinguishing trait between the two types of alpacas (Vicugna pacos), Huacaya and Suri. The Suri fleece type has been found to be inherited dominantly over the Huacaya type, resulting in offspring with the Suri phenotype. The aim of our study was to map genomic regions associated with the two different fleece types. In this study, 91 alpacas (54 Huacayas and 37 Suris) from Germany and Switzerland were genotyped using the 76k alpaca SNP array. Only 59k chromosome-localised markers map to the alpaca reference assembly VicPac3.1, and after quality control 49 866 SNPs, were retained for population structure assessment and to conduct a genome-wide association study. Both principal component and neighbour-joining tree analysis showed that the two fleece-type cohorts overlapped rather than forming two distinct clusters. Genome-wide significantly associated markers were observed in the scaffold region of chromosome 16 (NW_021964192.1), which contains a cluster of keratin genes. A haplotype predominantly found in Suri alpacas has been identified which supports dominant inheritance. Variant filtering of nine whole-genome sequenced alpacas from both fleece types in the critical interval of 0.4 Mb did not reveal perfect segregation of either fleece type for specific variants. To our knowledge, this is the first study to use the recently developed species-specific SNP array to identify genomic regions associated with differences in fleece type in alpacas. There are still some limitations, such as the preliminary status of the reference assembly and the incomplete annotation of the alpaca genome.
Subject(s)
Camelids, New World , Animals , Camelids, New World/genetics , Genome-Wide Association Study , Genotype , Phenotype , Genetic Markers , GenomicsABSTRACT
OBJECTIVE: The study investigated the association over time between the rates of anger/hostility and suicidality in post-9/11 veterans as a function of time following separation from the military and combat exposure. METHOD: Structured clinical interviews were conducted with N = 2,580 Iraq/Afghanistan-era U.S. military veterans serving since 9/11/01. For each participant, a postseparation interval was calculated as the time between military separation and the clinical interview, with a range of up to 9 years. Combat exposure was assessed using a three-level categorical proxy derived from the Combat Exposure Scale indexing levels of none, below, and above median exposure. Three separate estimates measuring anger/hostility and three separate measures of suicidality were modeled variously across separation intervals and levels of combat exposure. RESULTS: In bivariate analyses, higher levels of combat exposure were associated with overall significantly higher levels of both anger/hostility and suicidality. Based on multivariable analyses, rates in measures indexing suicidality among veterans did not decrease as a function of the number of years postseparation. In contrast, rates in measures indexing anger/hostility among veterans endorsing above-median levels of combat exposure decreased significantly with increasing time since separation. Nonetheless, even at longer time points, both suicidality and anger/hostility remained elevated among respondents endorsing above-median combat exposure. CONCLUSIONS: These findings illustrate the importance of implementing suicide prevention and anger management programs for postseparation adjustment as well as for the period beyond the immediate postseparation, with particular attention paid to the level of combat exposure experienced. (PsycInfo Database Record (c) 2023 APA, all rights reserved).
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Contemporary designs of engineering structures strive to minimize the use of material in order to reduce cost and weight. However, the approach taken by focusing on materials selection and on the design of the exterior shape of structures has reached its limits. By contrast, nature implements bottom-up designs based on a multiple-level hierarchy, spanning from nanoscale to macroscale, which evolved over millions of years in an environmentally sustainable manner given limited resources. Natural structures often appear as laminates in wood, bone, plants, exoskeletons, etc., and employ elaborate micro-structural mechanisms to generate simultaneous strength and toughness. One such mechanism, observed in the scorpion cuticle and in the sponge spicule, is the grading (gradual change) of properties like layers thickness, stiffness, strength and toughness. We show that grading is a biological design tradeoff, which optimizes the use of material to enhance survival traits such as endurance against impending detrimental cracks. We found that such design, when applied in a more vulnerable direction of the laminate, has the potential to restrain propagation of hazardous cracks by deflecting or bifurcating them. This is achieved by shifting material from non-critical regions to more critical regions, making the design sustainable in the sense of efficient use of building resources. We investigate how such a mechanism functions in nature and how it can be implemented in synthetic structures, by means of a generic analytical model for crack deflection in a general laminate. Such a mechanical model may help optimize the design of bioinspired structures for specific applications and, eventually, reduce material waste.
Subject(s)
Bone and Bones , Wood , Animals , ScorpionsABSTRACT
Development of biodegradable plastic materials is of primary importance in view of acute environmental and health problems associated with the accumulation of plastic waste. We fabricated a biodegradable composite material based on hydroxyethyl cellulose polymer and tyrosine nanocrystals, which demonstrates enhanced strength and ductility (typically mutually excluding properties), superior to most biodegradable plastics. This emergent behavior results from an assembly pattern that leads to a uniform nanoscale morphology and strong interactions between the components. Water-resistant biodegradable composites encapsulated with hydrophobic polycaprolactone as a protection layer were also fabricated. Self-assembly of robust sustainable plastics with emergent properties by using readily available building blocks provides a valuable toolbox for creating sustainable materials.
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Head kinematics are altered in individuals with vestibular schwannoma (VS) during short duration gait tasks [i.e., Functional Gait Assessment (FGA)], both before and after surgery, yet whether these differences extend to longer duration gait exercises is currently unknown. Here we examined the effects of vestibular loss and subsequent compensation on head kinematics in individuals with VS during gait exercises of relatively extended versus short duration (< 10 versus 30 s), compared to age-matched controls. Six-dimensional head movements were recorded during extended and short duration gait exercises before and then 6 weeks after sectioning of the involved vestibular nerve (vestibular neurectomy). Standard functional, physiological, and subjective clinical assessments were also performed at each time point. Kinematics were differentially altered in individuals with vestibular loss at both time points during extended versus short duration exercises. Range of motion was significantly reduced in extended tasks. In contrast, movement variability predominately differed for the short duration exercises. Overall, our results indicate that quantifying head kinematics during longer duration gait tasks can provide novel information about how VS individuals compensate for vestibular loss, and suggest that measurements of range of motion versus variability can provide information regarding the different strategies deployed to maintain functional locomotion.
Subject(s)
Head Movements , Neuroma, Acoustic , Humans , Biomechanical Phenomena , Exercise Therapy , Gait , LocomotionABSTRACT
Research has shown links between homelessness and criminal legal involvement in military veterans. The present study aimed to determine the magnitude and directionality of this association by investigating the incidence of, and factors associated with, homelessness preceding criminal arrest among veterans. Data on incarcerated veterans (N = 1,602) were analyzed from the 2016 Survey of Prison Inmates conducted by the U.S. Bureau of Justice Statistics. In this survey, 27% of incarcerated veterans reported homelessness 12 months before criminal arrest. In multivariable logistic regression analyses, higher odds of experiencing homelessness preceding criminal arrest were associated with younger age, non-White race, substance use disorder (with or without serious mental illness [SMI]), history of previous arrests, parental history of incarceration, and history of homelessness before age 18. These factors were found to be the same for nonveterans, as were rates of homelessness before arrest. However, incarcerated veterans were more likely to have mental disorders, including SMI, posttraumatic stress disorder (PTSD), and personality disorders. In contrast, incarcerated nonveterans were more likely to have a criminal history, including past arrests, parental incarceration, and juvenile detention. Although policymakers may be aware that some veterans they serve are at risk of criminal legal involvement, these national data reveal the magnitude and directionality of this problem: more than one in four incarcerated veterans experienced homelessness before criminal arrest. Identifying characteristics of veterans who experienced homelessness before criminal arrest directly informs service providers of demographic, historical, and clinical factors to evaluate and address to prevent criminal legal involvement. (PsycInfo Database Record (c) 2023 APA, all rights reserved).
Subject(s)
Criminals , Ill-Housed Persons , Prisoners , Substance-Related Disorders , Veterans , Humans , Adolescent , Prisons , Substance-Related Disorders/epidemiologyABSTRACT
Determining the optimal course of treatment for low grade glioma (LGG) patients is challenging and frequently reliant on subjective judgment and limited scientific evidence. Our objective was to develop a comprehensive deep learning assisted radiomics model for assessing not only overall survival in LGG, but also the likelihood of future malignancy and glioma growth velocity. Thus, we retrospectively included 349 LGG patients to develop a prediction model using clinical, anatomical, and preoperative MRI data. Before performing radiomics analysis, a U2-model for glioma segmentation was utilized to prevent bias, yielding a mean whole tumor Dice score of 0.837. Overall survival and time to malignancy were estimated using Cox proportional hazard models. In a postoperative model, we derived a C-index of 0.82 (CI 0.79-0.86) for the training cohort over 10 years and 0.74 (Cl 0.64-0.84) for the test cohort. Preoperative models showed a C-index of 0.77 (Cl 0.73-0.82) for training and 0.67 (Cl 0.57-0.80) test sets. Our findings suggest that we can reliably predict the survival of a heterogeneous population of glioma patients in both preoperative and postoperative scenarios. Further, we demonstrate the utility of radiomics in predicting biological tumor activity, such as the time to malignancy and the LGG growth rate.
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Deep Learning , Glioma , Humans , Precision Medicine , Retrospective Studies , Glioma/diagnostic imaging , Glioma/therapy , JudgmentABSTRACT
OBJECTIVE: Research examining social determinants of suicide risk in veterans suggests a potential link between food insecurity and subsequent suicidal ideation in military veterans. The objective of this study is to investigate, if and how, food insecurity predicts subsequent suicidal ideation in a nationally representative longitudinal survey of veterans. METHODS: A national longitudinal survey was analyzed of participants randomly drawn from over one million U.S. military service members who served after September 11, 2001. N = 1,090 veterans provided two waves of data one year apart (79% retention rate); the final sample was representative of post-9/11 veterans in all 50 states and all military branches. RESULTS: Veterans with food insecurity had nearly four times higher suicidal ideation one year later compared to veterans not reporting food insecurity (39% vs 10%). In multivariable analyses controlling for demographic, military, and clinical covariates, food insecurity (OR = 2.37, p =.0165) predicted suicidal ideation one year later, as did mental health disorders (OR = 2.12, p = .0097). Veterans with both food insecurity and mental health disorders had a more than nine-fold increase in predicted probability of suicidal ideation in the subsequent year compared to veterans with neither food insecurity nor mental health disorders (48.5% vs. 5.5%). CONCLUSION: These findings identify food insecurity as an independent risk marker for suicidal ideation in military veterans in addition to mental disorders. Food insecurity is both an indicator of and an intervention point for subsequent suicide risk. Regularly assessing for food insecurity, and intervening accordingly, can provide upstream opportunities to reduce odds of suicide among veterans.HIGHLIGHTSMilitary veterans with food insecurity were at elevated risk of suicidal ideation.Veterans with mental health disorders had higher odds of suicidal ideation one year later.Food insecurity plus mental health disorders led to a substantial increase in suicidal ideation.
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INTRODUCTION: This study validated Personality Assessment Inventory (PAI) Suicidal Ideation (SUI), Suicide Potential Index (SPI), and S_Chron scales against chronic and acute suicide risk factors and symptom validity measures. METHODS: Afghanistan/Iraq-era active-duty and Veteran participants completed a prospective study on neurocognition (N = 403) that included the PAI. The Beck Depression Inventory-II (specifically item 9) administered at two time points assessed acute and chronic suicide risk; the Beck Scale for Suicide Ideation item 20 identified history of suicide attempts. Major depressive disorder (MDD), posttraumatic stress disorder (PTSD), and traumatic brain injury (TBI) were evaluated using structured interviews and questionnaires. RESULTS: All three PAI suicide scales were significantly related to independent indicators of suicidality, with the largest effect for SUI (AUC 0.837-0.849). All three suicide scales were significantly related to MDD (r = 0.36-0.51), PTSD (r = 0.27-0.60), and TBI (r = 0.11-0.30). The three scales were not related to suicide attempt history for those with invalid PAI protocols. CONCLUSIONS: Although all three suicide scales do show significant relationships to other indicators of risk, SUI showed the highest association and greatest resistance to response bias.
Subject(s)
Depressive Disorder, Major , Military Personnel , Stress Disorders, Post-Traumatic , Suicide , Veterans , Humans , Suicidal Ideation , Depressive Disorder, Major/diagnosis , Afghanistan , Iraq , Prospective Studies , Stress Disorders, Post-Traumatic/diagnosis , Personality Assessment , Risk FactorsABSTRACT
A crack propagating through a laminate can cause severe structural failure, which may be avoided by deflecting or arresting the crack before it deepens. Inspired by the biology of the scorpion exoskeleton, this study shows how crack deflection can be achieved by gradually varying the stiffness and thickness of the laminate layers. A new generalized multi-layer, multi-material analytical model is proposed, using linear elastic fracture mechanics. The condition for deflection is modeled by comparing the applied stress causing a cohesive failure, resulting in crack propagation, to that causing an adhesive failure, resulting in delamination between layers. We show that a crack propagating in a direction of progressively decreasing elastic moduli is likely to deflect sooner than when the moduli are uniform or increasing. The model is applied to the scorpion cuticle, the laminated structure of which is composed of layers of helical units (Bouligands) with inward decreasing moduli and thickness, interleaved with stiff unidirectional fibrous layers (interlayers). The decreasing moduli act to deflect cracks, whereas the stiff interlayers serve as crack arrestors, making the cuticle less vulnerable to external defects induced by its exposure to harsh living conditions. These concepts may be applied in the design of synthetic laminated structures to improve their damage tolerance and resilience.
Subject(s)
Biology , Elastic ModulusABSTRACT
The multiscale structure of biomaterials enables their exceptional mechanical robustness, yet the impact of each constituent at their relevant length scale remains elusive. We used SAXD analysis to expose the intact chitin-fiber architecture within the exoskeleton on a scorpion's claw, revealing varying orientations, including Bouligand and unidirectional regions different from other arthropod species. We uncovered the contribution of individual components' constituent behavior to its mechanical properties from the micro- to the nanoscale. At the microscale, in-situ micromechanical experiments were used to determine site-specific stiffness, strength, and failure of the biocomposite due to fiber orientation, while metal-crosslinking of proteins is characterized via fluorescence maps. At the constituent level, combined with FEA simulations, we uncovered the behavior of fiber-matrix deformation with fiber diameter <53.7 nm and protein modulus in the range 1.4-11 MPa. The unveiled microstructure-mechanics relationship sheds light on the evolved structural functionalities and constituents' interactions within the scorpion cuticle. STATEMENT OF SIGNIFICANCE: The pincer exoskeleton is a fundamental part of the scorpion's body due to its multifunctionality. Precise structural and compositional analysis within the hierarchy is paramount to understand the fundamentals of the mechanical properties of the composite exoskeleton. Here, we expose the intact chitin-fiber architecture of the pincer exoskeleton using nondestructive analysis. In-situ mechanical characterization was performed at nanometer levels within the exoskeleton hierarchy, which complemented with simulations, uncovered the elastic modulus of the protein matrix. Our findings confirm the presence and distribution of metal ions and their role as reinforcements in the protein matrix via ligand coordinate bonds. In future work, these findings can be of great potential to inspire the design of composite materials.
Subject(s)
Exoskeleton Device , Scorpions , Animals , Ankle , Proteins , Chitin/chemistryABSTRACT
The German Society of Pneumology initiated 2021 the AWMF S1 guideline Long COVID/Post-COVID. In a broad interdisciplinary approach, this S1 guideline was designed based on the current state of knowledge.The clinical recommendations describe current Long COVID/Post-COVID symptoms, diagnostic approaches, and therapies.In addition to the general and consensus introduction, a subject-specific approach was taken to summarize the current state of knowledge.The guideline has an explicit practical claim and will be developed and adapted by the author team based on the current increase in knowledge.
Subject(s)
COVID-19 , Post-Acute COVID-19 Syndrome , HumansABSTRACT
Individuals with chronic liver disease (CLD) have an increased risk of bleeding from thrombocytopenia and changes in hemostasis. The aim of this study was to evaluate the frequency of and the factors associated with the occurrence of bleeding in CLD patients who underwent dental surgical procedures. This was a retrospective study whose data were collected in a hospital dentistry service between 2010 and 2016. The patients were referred from the gastroenterology and liver transplantation services of a university hospital for dental treatment. The study followed the STROBE guidelines. Among the 71 surgical procedures performed, there were 17 (24%) perioperative and postoperative bleeding episodes, 14 of which were in pretransplant patients and 11 received blood transfusion before dental surgery. Individuals with a previous history of bleeding (PRâ=â2.67, CIâ=â1.07-6.67, P â=â0.035) and those with a platelet count before surgery 50â×â10 9 /l or less (PRâ=â7.48, CIâ=â1.70-32.86, P â=â0.008) had a higher prevalence of perioperative and postoperative bleeding episodes than their peers without a previous history of bleeding, and those with platelet count greater than 50â×â10 9 /l. The approach to individuals with CLD is complex and represents a challenge to the clinician. A careful anamnesis combined with laboratory screening of coagulation disorders appears to be useful to identify individuals at a major risk of bleeding. Studies identifying the predisposing factors of bleeding in CLD patients support well tolerated protocols for oral surgery in this group.