Snap evaporation of droplets on smooth topographies

Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a “stick-slip” sequence—a combination of pinning and de-pinning events dominated by static friction or “pinning”, caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications

Psychiatric disorders and functional disability in outpatients with traumatic brain injuries

Objective: This study examined psychiatric sequelae of traumatic brain injuries in outpa-tients and their relation to functional disability. Method: Fifty consecutive outpatients with traumatic brain injuries who came to a brain injury rehabilitation clinic for initial evaluation were examined for DSM-III-R diagnoses with the use of the National Institute of Mental Health Diagnostic Interview Schedule. The patients completed the Medical Outcomes Study Health Survey to assess functional disability and a questionnaire to assess postconcussion symptoms and self-perceptions ofthe severity oftheir brain injuries and cognitive functioning. Results: Thirteen (26%) of the patients had current major depression, and an additional 14 (28%) reporteda first-onset major depressive episode after the injury that had resolved. Twelve (24%) had current generalized anxiety disorder, and four (8%) reported current substance abuse. The group with depression and/or anxiety was significantly more impaired than the nondepressed/nonanxious patients according to the Medical Outcomes Study Health Survey measures of emotional role functioning, mental health, and general health perceptions. The depressed/anxious group also rated their injuries as significantly more severe and their cogni-tive functioning as significantly worse, despite the lack of significant differences in objectiv

« On-the-go » multispectral imaging system to characterize the development of vineyard foliage

International audienceIn Precision Viticulture, multispectral imaging systems are currently used in remote sensing for vineyard vigor characterization but few are employed in proximal sensing. This work presents the potential of a proximal multispectral imaging system mounted on a track-laying tractor equipped with a Greenseeker RT-100 to provide an NDVI index. The camera acquired visible and near-infrared images which were calibrated in reflectance. Vegetation indices were computed and compared to Greenseeker data. From two of the resulting datasets, a spatio-temporal study of foliage description through both optical systems is presented. This first study assessed the proximal imagery regarding the similarity of results

Utilisation du trotteur (baby-trot, youpala): une conduite à risque

International audienc

Utilisation du trotteur (baby-trot, youpala): une conduite à risque

International audienc