Développement d'une méthodologie d'essais de fatigue vibratoire HCF pour les métaux

RÉSUMÉ Les moyens d’essais pour la caractérisation du comportement en fatigue à grand nombre de cycles (High Cycle Fatigue, ou HCF) des métaux sont multiples. Il existe notamment différents types de machine d’essai : servo-hydrauliques, rotatives, ultrasoniques, ou vibrophores. Les machines de flexion rotative ainsi que les montages ultrasoniques et les vibrophores sont généralement limités quant aux types de sollicitation pouvant être imposés. Les machines ultrasoniques ont l’avantage de générer des sollicitations à hautes fréquences - ce qui accélère l’exécution des essais - et de permettre d’investiguer le domaine de la fatigue à très grand nombre de cycles. Cependant, elles présentent l’inconvénient de ne pas toujours représenter les fréquences de sollicitation des pièces en service. Les machines servo-hyauliques permettent de générer plusieurs états de contrainte différents selon le montage employé. Ceci dit, ces montages sont souvent coûteux, inefficaces énergétiquement et limités aux basses fréquences. De plus, il est souvent nécessaire de modifier le montage ou de changer de machine pour modifier l’état de contrainte. Les méthodes vibratoires exploitant la résonance d’éprouvettes sur un pot vibrant sont prometteuses car elles sont relativement efficaces du point de vue énergétique. Elles permettent aussi de travailler sur une large plage de fréquence (jusqu’à quelques kHz au moins). De plus, il est possible d’obtenir différents types de sollicitations en conservant le même montage et en apportant des modifications mineures à la géométrie d’éprouvette. L’objectif de ce projet de recherche est d’explorer les différents états de contrainte qui peuvent être atteints par l’usage d’un pot vibrant et de développer une méthode d’essai robuste pour calibrer les critères de fatigue multiaxiale. Une revue des concepts de base de la fatigue HCF a permis d’identifier les mécanismes principaux liés à ce phénomène ainsi que les critères couramment utilisés afin de caractériser la tenue en fatigue uniaxiale et multiaxiale. Le critère de Dang Van permet de mettre en lumière la nécessité d’essais de fatigue multiaxiale afin de calibrer les modèles utilisés en conception. Les méthodologies expérimentales permettant de calibrer les critères de résistance en fatigue incluent les essais ultrasoniques, les essais sur vibrophore, les machines rotatives de type R.R. Moore, les machines servo-hydrauliques ainsi que les essais sur pot vibrant.---------- ABSTRACT A variety of High Cycle Fatigue testing methods based on different machines exist : sevo-hydraulic machines, rotating beam machines, ultrasonic machines or vibrophores. Vibrophores, rotating beam and ultrasonic machines are generally limited as to the achievable stress states. Ultrasonic machines have the advantage of generating high frequency cyclic loading – which reduces testing time – and allow for the investigation of Very High Cycle Fatigue. However, their high testing frequency is also a drawback insofar as it may not be representative of loading frequencies of actual parts in service. Servo-hydraulic machines can achieve a variety of different stress states depending of the particular machine and setup. That being said, these machines are often expensive, energetically inefficient and limited to low frequencies. In addition, it is often necessary to modify the setup or use a different machine to change the targeted stress state. Vibration based methods that exploit specimen resonance on an electrodynamic shaker are promising in part because they are relatively efficient from an energetic point of view. Furthermore, they allow for a wide range of testing frequencies (up to a few kHz at least) and can achieve a variety of stress states using the same setup and altering only the specimen geometry. The main objective of the research project is to explore the different stress states that can be achieved using an electrodynamic shaker and to develop a robust testing methodology to calibrate multiaxial fatigue criteria. A review of basic HCF fatigue concepts lead to the identification of the main mechanisms underlying this phenomenon as well as the usual criteria employed in order to characterize uniaxial and multiaxial fatigue. The Dang Van criterion in particular is used to illustrate the need for multiaxial fatigue testing in order to calibrate models that are used downstream in part design. Testing methodologies that allow for this kind of calibration include those based on R.R. Moore, sevo-hydraulic, ultrasonic machines as well as vibrophores or shakers. A comparative analysis reveals that shaker based methods could constitute an excellent way to easily test specimens under a wide range of stress states as well as loading frequencies for HCF tests. The following question then arises : what range of multiaxial stress states can be generated on a plate using a shaker

Shared and unique characteristics of metabolic syndrome in psychotic disorders: a review

Introduction: People with psychosis spectrum disorders (PSD) face an elevated risk of metabolic syndrome (MetS), which may reduce their life expectancy by nearly 20%. Pinpointing the shared and specific characteristics and clinical implications of MetS in PSD is crucial for designing interventions to reduce this risk, but an up-to-date review on MetS across the psychosis spectrum is lacking. Methods: This narrative review fills this gap by examining the clinical literature on characteristics and implications of MetS in both distinct PSD and transdiagnostically, i.e., across traditional categorical diagnoses, with a focus on psychiatric and cardio-metabolic management. Results: We discuss common and specific characteristics of MetS in PSD, as well as factors contributing to MetS development in PSD patients, including unhealthy lifestyle factors, genetic predisposition, pro-inflammatory state, drugs consumption, antipsychotic medication, and psychotic symptoms. We highlight the importance of early identification and management of cardio-metabolic risk in PSD patients, as well as the existing gaps in the literature, for instance in the screening for MetS in younger PSD patients. We compare hypotheses-generating clinical associations and characteristics of MetS in different PSD, concluding by reviewing the existing recommendations and challenges in screening, monitoring, and managing MetS in PSD. Conclusion: Early identification and management of MetS are crucial to mitigate the long-term cardio-metabolic toll in PSD patients. Interventions should focus on healthy lifestyle and appropriate pharmacological and behavioral interventions. Further translational and clinical research is needed to develop targeted interventions and personalized treatment approaches for this vulnerable population, aiming at improving physical health and overall well-being

Assessment of Autoimmune Responses Associated with Asbestos Exposure in Libby, Montana, USA

Systemic autoimmune responses are associated with certain environmental exposures, including crystalline particles such as silica. Positive antinuclear antibody (ANA) tests have been reported in small cohorts exposed to asbestos, but many questions remain regarding the prevalence, pattern, and significance of autoantibodies associated with asbestos exposures. The population in Libby, Montana, provides a unique opportunity for such a study because of both occupational and environmental exposures that have occurred as a result of the mining of asbestos-contaminated vermiculite near the community. As part of a multifaceted assessment of the impact of asbestos exposures on this population, this study explored the possibility of exacerbated autoimmune responses. Age- and sex-matched sets of 50 serum samples from Libby and Missoula, Montana (unexposed), were tested for ANA on HEp-2 cells using indirect immune, fluorescence. Data included frequency of positive tests, ANA titers, staining patterns, and scored fluorescence intensity, all against known controls. Serum immunoglobulin A (IgA), rheumatoid factor, and antibodies to extractable nuclear antigen (ENA) were also tested. The Libby samples showed significantly higher frequency of positive ANA and ENA tests, increased mean fluorescence intensity and titers of the ANAs, and higher serum IgA, compared with Missoula samples. In the Libby samples, positive correlations were found between ANA titers and both lung disease severity and extent of exposure. The results support the hypothesis that asbestos exposure is associated with autoimmune responses and suggests that a relationship exists between those responses and asbestos-related disease processes

' Pay-as-you-go City ': New Forms of Domesticity in a Technological Society

Ongoing urbanization, combined with market fundamentalism as the prevailing mode of political management, is leading to the spatial and social segregation of economic classes in cities. The housing market, being driven by economic interests rather than public policy, favors inflexible forms of ownership or tenancy that are increasingly incompatible with the more diverse forms of live-work patterns and family structures occurring in the society. This paper presents a research-by-design project that explores a speculative future scenario of housing, based on current developments in digital technologies and their impact on the mobility and accessibility to services enjoyed by urban residents. It references technology platforms that underpin the 'sharing economy' or 'gig economy', such as 'pay-as-you-go' car and bike sharing programs or internet and smartphone-based services for taxis or temporary accommodation. The study explores how new forms of participation in the housing market could circumvent the current segregation of different communities across the city. It describes a speculative system of distributed residential spaces, accessible to all on a 'pay-for-time-used' basis. By offering freedom of choice across domestic functions of greater range and accessibility than found within existing housing or hotel accommodation, the system would enable opportunistic or nomadic forms of living linked to the dynamic spatio-temporal occurrences of social, cultural or economic opportunities. The research references how new forms of social networking create new challenges and opportunities to participate in communities and explores how new technologies, applied to housing, can help to find a 'sense of belonging' within the technological society

Admissions to psychiatric inpatient services and use of coercive measures in 2020 in a Swiss psychiatric department: An interrupted time-series analysis.

BACKGROUND The CoVID pandemic and the associated lockdown had a significant impact on mental health services. Inpatient services faced the challenge of offering acute psychiatric while implementing strict infection control measures. There is, however, a lack of studies investigating the use of coercive measures during the pandemic and their relation to hospitalizations and symptom severity. AIMS To investigate the effects of the CoVID outbreak on psychiatric admissions, use of seclusion and symptom severity. METHOD Using routine data from 2019 and 2020 gathered in the Department of Psychiatry at the Geneva University Hospitals, we performed an interrupted time series analysis. This included the number of psychiatric hospitalizations, the proportion of people who experienced seclusion and the average severity of symptoms as measured by the Health of Nations Outcome Scale (HoNOS). Dependent variables were regressed on the time variable using regression model with bootstrapped standard errors. RESULTS Hospitalizations decreased over time (b = -0.57, 95% CI: -0.67; -0.48, p < .001). A structural break in the data (supremum Wald test: p < .001) was observed in the 12th week of 2020. There was an inverse relationship between the number of admissions and the proportions of people subject to seclusion (b = 0.21, 95% CI: -0.32; -0.09, p < .001). There was a statistically marginally significant inverse relationship between HoNOS scores at admission and the number of psychiatric hospitalizations (b = -1.28, 95% CI: -2.59, 0.02, p = .054). CONCLUSION Our results show that the CoVID pandemic in 2020 was associated with a significant decrease in the number of hospital admissions. This decrease was correlated with a greater use of seclusion. The higher burden of symptoms and the difficult implementation of infection control measures might explain this higher use of coercion

Unexpected Complication During Stent Placement for Esophageal Cancer

Background: Due to the delay in esophageal cancer until the late stages, its mortality rate is relatively high. One of the most common presentations of advanced esophageal cancer is dysphagia. Esophageal stenting is a palliative treatment modality to resolve dysphagia and restore oral intake. Despite this advantage, stenting has various complications. Aim: We reported a case of active bleeding after esophageal stenting. Case presentation: A case of a complication caused by an esophageal stent placement for carcinoma is presented. The placement of the stent was difficult under fluoroscopic control, which led to some pushing, resulting in a wound in the pharynx with active bleeding without perforation. The bleeding was successfully controlled by the surgeon. Therefore, the patient was postponed a few days later and we preferred this time to put a stent through the scope without complications. Conclusion: Active bleeding is one of the esophageal stenting complications. In this article, we reported a middle-aged woman with advanced esophageal cancer who underwent esophageal stenting. Afterward, she developed active bleeding, which was successfully managed

Treatment without consent in adult psychiatry inpatient units: a retrospective study on predictive factors

BackgroundCoercion is one of the most important challenges in mental health. In Switzerland, forced medication can be applied during an emergency (Art. 435 of the Civil Code) or over a longer period in case of endangerment of others or oneself (Art. 434). We aimed to analyze the predictors of this specific treatment without consent.MethodsForced medication prescriptions in the Division of Adult Psychiatry of the Geneva University Hospitals between 2018 and 2021 were retrospectively analyzed. Medication under Article 434 was the main outcome variable. Age, gender, admission mode, main diagnosis, and the Health of the Nation Outcome Scales (HoNOS) score at admission were considered as potential predictors. T-test and Pearson’s chi-square test were used to compare continuous and categorical variables. A logistic regression was performed to find significant predictors of forced medication.ResultsSeventy-one out of 4,326 inpatients were subjected to forced medication under Art. 434. HoNOS global scores at admission were not significantly different in the forced medication group compared to the control group. Aggressive behavior was lower in the former at the univariate level. Forced medication was associated at the multivariate level with female gender, involuntary admission, and psychosis.ConclusionWomen suffering from psychosis are more at risk of receiving involuntary and repeated medication. The risk of deterioration in psychosocial functioning or behavioral disorganization seems to be the main argument for this coercive measure. Future studies should focus on the patient’s perception of this coercion to prevent it and improve adherence to care. Follow-up after discharge might be useful to evaluate a long-term benefit

Place de la laparoscopie dans la prise en charge des anomalies de différenciation sexuelle: à propos de 4 cas

Les troubles de la différenciation sexuelle sont à l'origine d'une discordance entre le sexe proprement dit (phénotypique) et le sexe génétique (génotypique) ce qui pose un problème de détermination du sexe. Dans les pays de faible niveau socio-économique où le diagnostic anténatal est souvent absent et les plateaux techniques insuffisants, la prise en charge médico-chirurgicale est difficile. Le but de ce travail est de préciser la place de la laparoscopie dans la prise en charge de l'ambiguïté sexuelle à travers l'observation de 4 cas et une revue de la littérature.Pan African Medical Journal 2016; 2