On the auxetic properties of generic rotating rigid triangles

Materials having a negative Poisson’s ratio (auxetic) get fatter rather than thinner when uniaxially stretched. This phenomenon has been often explained through models that describe how particular geometric features in the micro or nanostructure of the material deform when subjected to uniaxial loads. Here, a new model based on scalene rigid triangles rotate relative to each other will be presented and analysed. It is shown that this model can afford a very wide range of Poisson’s ratio values, the sign and magnitude of which depends on the shape of the triangles and the angles between them. This new model has the advantage that it is very generic and may be potentially used to describe the properties in various types of materials, including auxetic foams and their relative surface density. Specific applications of this model, such as a blueprint for a system that can exhibit temperature-dependent Poisson’s ratios, are also discussed.peer-reviewe

The role of cognitive effort in subjective reward devaluation and risky decision-making

Motivation is underpinned by cost-benefit valuations where costs—such as physical effort or outcome risk—are subjectively weighed against available rewards. However, in many environments risks pertain not to the variance of outcomes, but to variance in the possible levels of effort required to obtain rewards (effort risks). Moreover, motivation is often guided by the extent to which cognitive—not physical—effort devalues rewards (effort discounting). Yet, very little is known about the mechanisms that underpin the influence of cognitive effort risks or discounting on motivation. We used two cost-benefit decision-making tasks to probe subjective sensitivity to cognitive effort (number of shifts of spatial attention) and to effort risks. Our results show that shifts of spatial attention when monitoring rapidly presented visual stimuli are perceived as effortful and devalue rewards. Additionally, most people are risk-averse, preferring safe, known amounts of effort over risky offers. However, there was no correlation between their effort and risk sensitivity. We show for the first time that people are averse to variance in the possible amount of cognitive effort to be exerted. These results suggest that cognitive effort sensitivity and risk sensitivity are underpinned by distinct psychological and neurobiological mechanisms

A Delphi Consensus Report From VASCUNET and International Consortium of Vascular Registries

Copyright © 2024. Published by Elsevier B.V.OBJECTIVE: Outcome registries in vascular surgery are increasingly used to drive quality improvement by vascular societies. The VASCUNET collaboration, within the European Society for Vascular Surgery (ESVS), and the International Consortium of Vascular Registries (ICVR) developed a set of variables for quality improvement registries on abdominal aortic aneurysm (AAA) repair as a registry standard. METHODS: Representatives from international vascular registries within VASCUNET, ICVR, and other nations with established registries were invited to provide the variables. The final variables were developed through a two stage modified Delphi process. Variables from the established registries with at least 60% consensus among all the registries were included for round 1. A five point Likert scale (strongly disagree to fully agree) was used. If the limit of consensual agreement was not reached in round 1, the variable was discussed again in round 2. For round 2, an array question method (yes, no to unsure) was used. Agreement of at least 70% resulted in the variable being included in the final dataset. RESULTS: A total of 88 out of 371 variables extracted from all AAA registries were circulated in the modified Delphi process as they reached the 60% consensus threshold. The questionnaire was circulated to 55 participants (round 1: 49; 89%; round 2: 43; 78%). After two rounds, 70 variables were recommended on consensual agreement. These variables comprised demographics (n = 4), pre-operative information (n = 28), intra-operative variables (n = 18), post-operative variables (n = 5), and follow up (n = 13). CONCLUSION: Based on this modified Delphi process, an international panel of vascular surgeons representing quality improvement registries recommended 70 core variables as standard in registries on AAA repair. The inclusion of a core set of variables in AAA vascular registries may help to further harmonise observational research and quality of AAA repair among global healthcare systems.proofepub_ahead_of_prin

Covid-19 pandemic lockdown : Uncovering the hard truth on lower limb ischaemic outcomes? A single centre observational study

The COVID-19 pandemic disrupted hospital services worldwide and Malta was no exception. This was especially true for vascular surgery where societies issued recommendations on how to adjust their services during the first wave of the pandemic. Malta has one tertiary hospital, with a vascular unit that was established in 2007. Since then, all lower limb procedures have been registered in the Maltese vascular registry (MaltaVasc), which has been internationally validated. In Malta, COVID-positive patient zero was recorded on 7 March 2020. The closure of the only airport was carried out on 21 March and a partial intelligence lockdown was started on 27 March, whereby vulnerable patients were advised to stay home and avoid going to work. On 5 June 2020, the government of Malta and Public Health authorities eased the lockdown for vulnerable patients and on 1 July 2020 the airport was opened to 19 destinations, with a gradual opening to other countries. Despite the partial lockdown, patients with hospital appointments were advised to keep their appointments unless they were cancelled by medical staff. Elective lists were reduced and non-urgent surgeries postponed. During this time, it was noted that few patients were presenting to hospital with signs and symptoms of chronic limb threatening ischaemia (CLTI). Furthermore, it was felt that patients with CLTI were presenting to hospital late, requiring either palliation or major amputation, and more patients required major amputation than in previous years. The primary aim of this study was to analyse the number of major and minor amputations, elective and/or urgent and emergency revascularisation procedures during the first wave of the COVID-19 pandemic. The secondary aims were to compare the number of lower limb procedures with the previous year and also to compare the rates of major amputations with the prevascular unit time period where few lower limb revascularisations were carried by the same authors.peer-reviewe

Classification des potentiels évoqués par corrélation de Pearson dans une interface cerveau-ordinateur

National audienceDans cette communication, nous décrivons et évaluons les performances d'une technique d'apprentissage des coefficients d'un classifieur linéaire utilisé dans une interface cerveau-ordinateur. Les signaux de l'électroencéphalogramme d'un individu sont analysés au moyen de cette technique afin de mettre en évidence les réponses de ce dernier à des stimuli visuels. Le traitement et la classification des signaux sont utilisés afin d'implanter un système de communication palliative permettant à l'individu d'épeler des mots. Les performances de la méthode de classification ont été évaluées par une expérimentation sur huit personnes

Assessing how metal reef restoration structures shape the functional and taxonomic profile of coral-associated bacterial communities

Significant threats to the long-term persistence of coral reefs have accelerated the adoption of coral propagation and out-planting approaches. However, how materials commonly used for propagation structures could potentially affect coral-associated bacterial communities remains untested. Here, we examined the impact of metal propagation structures on coral-associated bacterial communities. Fragments of the coral species Acropora millepora were grown on aluminium, sand/epoxy-coated steel (Reef Stars), and uncoated steel (rebar) structures. After 6 months, the functional and taxonomic profiles of coral-associated bacterial communities of propagated corals and reef colonies were characterised using amplicon (16S rRNA gene) and shotgun metagenomic sequencing. No differences in the phylogenetic structure or functional profile of coral-associated bacterial communities were observed between propagated corals and reef colonies. However, specific genes and pathways (e.g., lipid, nucleotide, and carbohydrate metabolism) were overrepresented in corals grown on different materials, and different taxa were indicative of the materials. These findings indicate that coral propagation on different materials may lead to differences in the individual bacterial taxa and functional potential of coral-associated bacterial communities, but how these contribute to changed holobiont fitness presents a key question to be addressed

RNA sequencing-based transcriptome profiling of cardiac tissue Implicados novela putative disease mechanisms in FLNC-associated arrhythmogenic cardiomyopathy.

Arrhythmogenic cardiomyopathy (ACM) encompasses a group of inherited cardiomyopathies including arrhythmogenic right ventricular cardiomyopathy (ARVC) whose molecular disease mechanism is associated with dysregulation of the canonical WNT signalling pathway. Recent evidence indicates that ARVC and ACM caused by pathogenic variants in the FLNC gene encoding filamin C, a major cardiac structural protein, may have different molecular mechanisms of pathogenesis. We sought to identify dysregulated biological pathways in FLNC-associated ACM. RNA was extracted from seven paraffin-embedded left ventricular tissue samples from deceased ACM patients carrying FLNC variants and sequenced. Transcript levels of 623 genes were upregulated and 486 genes were reduced in ACM in comparison to control samples. The cell adhesion pathway and ILK signalling were among the prominent dysregulated pathways in ACM. Consistent with these findings, transcript levels of cell adhesion genes JAM2, NEO1, VCAM1 and PTPRC were upregulated in ACM samples. Moreover, several actin-associated genes, including FLNC, VCL, PARVB and MYL7, were suppressed, suggesting dysregulation of the actin cytoskeleton. Analysis of the transcriptome for biological pathways predicted activation of inflammation and apoptosis and suppression of oxidative phosphorylation and MTORC1 signalling in ACM. Our data suggests dysregulated cell adhesion and ILK signalling as novel putative pathogenic mechanisms of ACM caused by FLNC variants which are distinct from the postulated disease mechanism of classic ARVC caused by desmosomal gene mutations. This knowledge could help in the design of future gene therapy strategies which would target specific components of these pathways and potentially lead to novel treatments for ACM

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication