Création de structures à précontrainte adaptative à base d'alliages à mémoire de forme

International audienceL'étude porte sur l'utilisation de fils en alliage à mémoire de forme (AMF) pour créer des systèmes mécaniques actifs. Il s'agit en pratique de contrôler l'état de contrainte ou de déformation d'une structure par activation thermique de l'effet mémoire de fils AMF connectés à la structure. Un point clé consiste à n'utiliser que des fils AMF classiques, i.e. à effet mémoire simple-sens, pour créer une activation à double-sens de la structure. Trois dispositifs sont développés et étudiés. Dans un premier temps, le cas simple de deux fils AMF placés en série est considéré. Le chauffage des fils est assuré par effet Joule. Ce dispositif permet d'analyser comment deux fils à effet mémoire simple-sens peuvent interagir pour permettre le pilotage double-sens d'un déplacement. Le cas d'une poutre console équipée de fils AMF est ensuite considéré. Il est montré qu'il est possible de contrôler en temps réel la flèche de la poutre par un chauffage sélectif des fils. Enfin, le cas d'une poutrelle sur deux appuis et soumise à une charge mobile est étudié. Une limitation en temps réel de la valeur de la flèche a été possible en utilisant un unique fil AMF précontraint. Cette étude montre que des AMF peuvent être utilisés pour contrôler l'état de déformation d'une structure ou d'adapter un état de précontrainte en fonction d'une variation de charge

Cognitive impairment in essential tremor assessed by the cerebellar cognitive affective syndrome scale

BackgroundEssential tremor (ET) is a movement disorder characterized by cerebellar neurodegenerative changes. ET is also associated with non-motor symptoms including cognitive impairment. The neuropsychologic profile of a patient with ET could relate to cerebellar cognitive affective syndrome (CCAS).ObjectiveThis study aimed to assess the prevalence of cognitive impairment in patients with ET and identify whether the cognitive impairment in ET corresponds to a CCAS.MethodsCognitive functions were evaluated with the CCAS-Scale (CCAS-S) in 20 patients with ET and 20 controls matched for age, sex, and level of education. The results of the CCAS-S were compared between patients and controls. The underlying determinant of CCAS inpatients with ET was identified through the correlation between the results of the CCAS-S and age at onset of symptoms, disease duration, and the Essential Tremor Rating Assessment Scale (TETRAS).ResultsOn a group level, ET patients performed significantly worse than matched controls. In total, 13 individuals with ET had a definite CCAS (CCAS-S failed items ≥ 3). ASO and TETRAS scores significantly correlated with CCAS-S performances in ET patients.ConclusionCCAS is highly prevalent in patients with ET which supports the cerebellar pathophysiology of associated cognitive impairment and supports a more systematic use of the CCAS-S to cognitively assessed patients with ET

Family ENgagement in Intensive Care Environments (FENICE): A quasi-experimental study protocol

Even if health care professionals should take into account the active involvement of families in Intensive Care Units (ICUs), little research that investigates family member\u2019s contributions to care and includes its outcomes on both the family itself and the patient care, is available. The aim of this research project is to assess the effects of a family engagement program on family members\u2019 satisfaction and on patients\u2019 well-being and quality of life. A quasiexperimental study with two non-randomized groups (94 per each group) will be performed in two general ICUs of an Academic Italian Hospital. The intervention will be carried out in a single ICU and it consists of family members\u2019 involvement in the care of their loved ones by means of bed physical exercises and simple care tasks. Participants will be evaluated through manifold outcomes: family satisfaction, assessed with the FS-ICU tool within 48 hours after ICU discharge; patients\u2019 sense of well-being, measured with a visual analogue scale within 30 minutes after the time period of a visit; and the quality of life, investigated with the SF- 12 questionnaire within the first 48 hours after admission to ICU, at three and six months after ICU discharge by telephone. From July 2020, 188 subjects are going to be enrolled throughout the year. The latest data will be collected in December 2021 to allow the completion of the follow-ups of all participants. First, this study constitutes a significant step in a research agenda aimed at deepening the nursing sensitive outcomes in ICUs and the quality of hospital care. Secondly, the results of this study might have the potential to provide a better understanding of how families may modify patients\u2019 outcomes and whether family members would benefit from an involvement program

TWIG: A model to simulate the gravitropic response of a tree axis in the frame of elasticity and viscoelasticity, at intra-annual time scale

International audienceTrees are able to maintain or to modify the orientation of their axes (trunks or branches) by tropic movements. For axes in which elongation is achieved but cambial growth active, the tropic movements are due to the production of a particular wood, called reaction wood which is prestressed within the growing tree. Several models have been developed to simulate the gravitropic response of axes in trees due to the formation of reaction wood, all within the frame of linear elasticity and considering the wood maturation as instantaneous. The effect viscoelasticity of wood has, to our knowledge, never been considered. The TWIG model presented in this paper aims at simulating the gravitropic movement of a tree axis at the intra-annual scale. In this work we studied both the effect of a non instantaneous maturation process and of viscoelasticity. For this purpose, we considered the elastic case with maturation considered as an instantaneous process as the reference. The introduction of viscoelasticity in TWIG has been done by coupling TWIG to a model developed for bridges. Indeed from a purely mechanical point of view, bridges and trees are very similar: they are structures which are built in stages, they are made of several materials (composite structures), their materials are prestressed (wood is prestressed during the maturation process as a result of polymerisation of lignin and cellulose to form the secondary cell wall and concrete is prestressed during drying). Simulations gave evidence that the reorientation process of axes can be significantly influenced by the kinetics of maturation. Moreover the model has now to be tested with more experimental data of wood viscoelasticity but it appears that in the range of a relaxation time from 0 to 50 days, viscoelasticity has an important effect on the evolution of tree shape as well as on the values of prestresses

Nursing care factors influencing patients' outcomes in the intensive care unit: Findings from a rapid review

4To examine the nursing care factors investigated regarding their influence on outcomes of critically ill patients.openopenDanielis, Matteo; Destrebecq, Anne Lucia Leona; Terzoni, Stefano; Palese, AlvisaDanielis, Matteo; Destrebecq, Anne Lucia Leona; Terzoni, Stefano; Palese, Alvis

Proprioceptive and tactile processing in individuals with Friedreich ataxia: an fMRI study

ObjectiveFriedreich ataxia (FA) neuropathology affects dorsal root ganglia, posterior columns in the spinal cord, the spinocerebellar tracts, and cerebellar dentate nuclei. The impact of the somatosensory system on ataxic symptoms remains debated. This study aims to better evaluate the contribution of somatosensory processing to ataxia clinical severity by simultaneously investigating passive movement and tactile pneumatic stimulation in individuals with FA.MethodsTwenty patients with FA and 20 healthy participants were included. All subjects underwent two 6 min block-design functional magnetic resonance imaging (fMRI) paradigms consisting of twelve 30 s alternating blocks (10 brain volumes per block, 120 brain volumes per paradigm) of a tactile oddball paradigm and a passive movement paradigm. Spearman rank correlation tests were used for correlations between BOLD levels and ataxia severity.ResultsThe passive movement paradigm led to the lower activation of primary (cSI) and secondary somatosensory cortices (cSII) in FA compared with healthy subjects (respectively 1.1 ± 0.78 vs. 0.61 ± 1.02, p = 0.04, and 0.69 ± 0.5 vs. 0.3 ± 0.41, p = 0.005). In the tactile paradigm, there was no significant difference between cSI and cSII activation levels in healthy controls and FA (respectively 0.88 ± 0.73 vs. 1.14 ± 0.99, p = 0.33, and 0.54 ± 0.37 vs. 0.55 ± 0.54, p = 0.93). Correlation analysis showed a significant correlation between cSI activation levels in the tactile paradigm and the clinical severity (R = 0.481, p = 0.032).InterpretationOur study captured the difference between tactile and proprioceptive impairments in FA using somatosensory fMRI paradigms. The lack of correlation between the proprioceptive paradigm and ataxia clinical parameters supports a low contribution of afferent ataxia to FA clinical severity

Indagine trasversale sull'abbandono del corso di laurea in infermieristica presso l'Università degli Studi di Milano

Introduzione Secondo le stime dell\u2019OCSE, in Italia mancano circa 100.000 infermieri; \ue8 quindi necessario supportare gli studenti motivati che intraprendono il Corso di Laurea in Infermieristica, con misure mirate a ridurre i tassi di abbandono e di insuccesso accademico senza intaccare la qualit\ue0 della formazione. Data la scarsit\ue0 di studi condotti nel nostro paese sull\u2019argomento, con questa indagine ci siamo proposti di raccogliere informazioni sulle caratteristiche degli studenti che hanno abbandonato il Corso di Laurea in Infermieristica (CLI) dell\u2019Universit\ue0 degli Studi di Milano tra il 2006 e il 2009. Materiali e metodi L\u2019indagine \ue8 stata condotta, utilizzando un questionario semistrutturato autosomministrato, su un campione formato da ex studenti che avevano abbandonato il CLIal primo anno di corso. Risultati Il questionario compilato \ue8 stato restituito da 90 soggetti, in prevalenza di nazionalit\ue0 italiana (83) e di sesso femminile (59), con un\u2019et\ue0 media di 27 anni. La maggior parte ha riportato che avrebbe preferito intraprendere altri corsi di laurea. Ifattor i pi\uf9 frequentemente indicati come cause dell\u2019abbandono del CLIin cludevano la delusione delle aspettative, la pesantezza del corso di studi, il carico familiare e problemi economici o di salute. Conclusioni Le risposte fornite dai partecipanti all\u2019indagine indicano che spesso la scelta del CLIn on \ue8 supportata da idee chiare e motivazioni forti. Idati raccolti suggeriscono, tra i possibili approcci per ridurre il rischio di insuccesso accademico degli studenti infermieri, il potenziamento del tutorato e una diversa gestione dei piani di studio

Comportement vis-à-vis du flambage d'une structure multi-matériaux assemblée par collage

Ce travail s'intéresse au comportement et à la résistance du joint dans les composants unidimensionnels multi-matériaux assemblés par collage et sollicités en flexion par flambage. Une approche multi-échelle est développée pour l'analyse du mécanisme d'interaction entre support, raidisseur et joint de colle et pour la détermination des contraintes dans le joint de colle. Dans un premier temps, la structure est homogénéisée afin d'analyser son comportement global dans le cadre classique de la théorie des poutres. Puis une méthode de localisation permet d'expliciter l'état de contraintes au sein des éléments constitutifs du composant et notamment du joint de colle. L'approche est appliquée à des composants simplement fléchis, puis à des composants sollicités en flambage. La validité de l'approche analytique proposée est discutée par comparaison avec des simulations numériques de deux structures types

Alzheimer’s Disease (AD) Detect & Prevent: presymptomatic AD detection and prevention

Alzheimer’s disease (AD) is a major cause of the rapidly growing and crushing aging challenge that threatens to economically undermine today’s healthcare system. AD prevalence will grow to over 100 million cases in 2050. AD is incurable but can be prevented. Therefore, the most viable solution may be to detect very early signs of AD (presymptomatically) in citizens-at-risk and to intervene in time to reduce AD risk or prevent it entirely. The present project will refine and validate two breakthrough innovations for AD detection and AD prevention and commercialize them as a one-stop digital medical device, named ‘AD Detect & Prevent’. The first innovation is a highly sensitive cognitive assessment method recently pioneered by a group of researchers that has been shown to detect subtle presymptomatic stage cognitive decline specific to AD. This will be integrated with the second innovation – a digital AD prevention programme delivered on an award-winning computerized cognitive training and rehabilitation platform (app + web) that uses high intensity immersive and adaptive ‘neurogames’ and audio-based therapy for behavioural intervention, designed for strengthening core cognitive functions, building cognitive reserve, changing lifestyle and thus reducing the overall AD risk in individuals. The detection and prevention methods will undergo vigorous scientific validation, and the ambition is to create and become the global standard of care for precise presymptomatic detection of AD and effective AD prevention

Influence de la courbure d'un fil en AMF sur son comportement en traction dans une perspective de confinement de composants en béton

L'étude porte sur la création de contrainte dans un fil en alliage à mémoire de forme (AMF) enroulé sur un substrat de forme cylindrique. Les essais sont réalisés sur des fils en Ni-Ti initialement à l'état martensitique. Un modèle thermomécanique est adapté afin d'analyser les résultats expérimentaux. Les contraintes apparaissant lors de l'activation thermique de l'effet mémoire sont étudiées. L'influence de la courbure du fil est analysée. L'asymétrie traction-compression de la réponse de l'AMF est prise en compte dans cette étude