Nonspherical armoured bubble vibration.

In this paper, we study the dynamics of cylindrical armoured bubbles excited by mechanical vibrations. A step by step transition from cylindrical to spherical shape is reported as the intensity of the vibration is increased, leading to a reduction of the bubble surface and a dissemination of the excess particles. We demonstrate through energy balance that nonspherical armoured bubbles constitute a metastable state. The vibration instills the activation energy necessary for the bubble to return to its least energetic stable state: a spherical armoured bubble. At this point, particle desorption can only be achieved through higher amplitude of excitation required to overcome capillary retention forces. Nonspherical armoured bubbles open perspectives for tailored localized particle dissemination with limited excitation power.

Dynamics of liquid plugs in prewetted capillary tubes: from acceleration and rupture to deceleration and airway obstruction.

The dynamics of individual liquid plugs pushed at a constant pressure head inside prewetted cylindrical capillary tubes is investigated experimentally and theoretically. It is shown that, depending on the thickness of the prewetting film and the magnitude of the pressure head, the plugs can either experience a continuous acceleration leading to a dramatic decrease of their size and eventually their rupture or conversely, a progressive deceleration associated with their growth and an exacerbation of the airway obstruction. These behaviors are quantitatively reproduced using a simple nonlinear model [Baudoin et al., Proc. Natl. Acad. Sci. U. S. A., 2013, 110, 859] adapted here for cylindrical channels. Furthermore, an analytical criterion for the transition between these two regimes is derived and successfully compared with extensive experimental data. The potential implications of this work for pulmonary obstructive diseases are discussed.

Dynamics of sessile and pendant drops excited by surface acoustic waves: Gravity effects and correlation between oscillatory and translational motions.

When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed, the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or, more generally, by an initial or dynamically induced stretching of the drop. In turn, we elucidate the origin of the resonance frequency shift, as well as the origin of the strong correlation between oscillatory and translational motion. We show that for sessile drops, the velocity is mainly determined by the amplitude of oscillation and that the saturation observed is due to the nonlinear dependence of the drop response frequency on the dynamically induced stretching.

[Acute cough in infants: impact of national guidelines on medical practices in a French department]. / Recommandations de l'Agence nationale de sécurité du médicament concernant le traitement de la toux aiguë du nourrisson : évaluation des pratiques médicales dans les Alpes-Maritimes.

CONTEXT AND AIM: Guidelines have been published regularly since 2010 by the ANSM (the Health Products Safety Agency) advising against antitussive drugs for infants because of their inefficacy and their side effects (convulsions, respiratory congestion). Antihistamines, mucolytics, and terpene-based suppositories have theoretically disappeared from infant pharmacopoeia. We assessed the degree of compliance with these guidelines on the part of health professionals. MATERIALS AND METHODS: From June 2012 to August 2012, 198 general practitioners and 44 pediatricians were assessed in the Alpes-Maritimes department of France by means of questionnaires. At the same time, an analysis of medical prescriptions was sought from the Regional Directorate of Medical Services (RDMS) of the PACA-Corse region Health Insurance. RESULTS: The rate of noncompliance with the contraindications was 14.9% (17.7% general practitioners and 2.3% pediatricians). The RDMS study showed a slight decrease in prescriptions for antitussives not recommended from 2011 to 2012: -21% for pediatricians, -15.5% for generalist physicians. CONCLUSION: Continued educational and informative campaigns are therefore needed to stop medical prescriptions of cough medicines for infants, which should also involve parents.

[Acute cough in infants: impact on families and pharmacists of contraindications of the Agence nationale de sécurité du médicament et des produits de santé (ANSM)]. / Recommandations de l'Agence nationale de sécurité du médicament et des produits de santé (ANSM) concernant la prise en charge de la toux aiguë du nourrisson : impact sur les familles et les pharmacies.

CONTEXT AND OBJECTIVE: Although commonplace and usually not serious, acute cough in the context of upper respiratory tract infection is a frequent reason for consultation and generates significant parental anxiety. Parents often request active drug intervention. Following the contraindications in infants of mucolytics, Hélicidine(®), antihistamines, and terpene-based suppositories, issued between 2010 and 2011 by the Agence nationale de sécurité du médicament et des produits de santé (ANSM), we wished to assess whether these contraindications were known by parents and applied in pharmacies. MATERIALS AND METHODS: An assessment of compliance with these contraindications was made by a double declarative prospective observational study in Nice, first with 29 pharmacists and pharmacy technicians (4-25 August 2012) and then with 289 parents of infants (December 2011 to April 2012). RESULTS: The rate of noncompliance with contraindications was 23.8 % for parents and 34.5 % of pharmacists and pharmacy technicians. Consumption of cough medicines was inversely correlated to the ability to perform a correct nasal wash (OR=2.3). Only 21 % of parents used nasal wash properly. Full-time work was a risk factor for noncompliance with contraindications (OR=1.91). CONCLUSION: ANSM contraindications still have a limited impact on pharmacists and families. Therefore, efforts must be pursued to stop delivering cough medicines for infants. The information and educational campaigns should also involve parents and help to improve nasal wash use.

Droplet displacements and oscillations induced by ultrasonic surface acoustic waves: a quantitative study.

We present an experimental study of a droplet interacting with an ultrasonic surface acoustic wave. Depending on the amplitude of the wave, the drop can either experience an internal flow with its contact line pinned, or (at higher amplitude) move along the direction of the wave also with internal flow. Both situations come with oscillations of the drop free surface. The physical origins of the internal mixing flow as well as the drop displacement and surface waves are still not well understood. In order to give insights of the underlying physics involved in these phenomena, we carried out an experimental and numerical study. The results suggest that the surface deformation of the drop can be related to a combination between acoustic streaming effect and radiation pressure inside the drop.

Preliminary findings from the National Pre-ESRD Education Initiative.

Regardless of age or race, more patients preferred peritoneal dialysis (PD) than would be expected from the current ratio of patients treated with PD in the U.S. The percent of patients choosing PD seems to be largely influenced by the scope of information they receive prior to therapy initiation. In the absence of thorough treatment option education, a significant number of patients may be assigned a therapy when, in reality, they would have selected an alternative option. There is a need to further understand the correlation between a practice's PD utilization rate and the extent to which patients are given dialysis treatment options.

Brain damage in the premature infant. Early lesions and new aspects of sequelae.

In spite of a significant decrease of the mortality and morbidity of neonates, cerebral damage in the premature infant remains the major concern for the neonatologist. Intraventricular hemorrhage (IVH) and necrosis of the white matter (leukomalacia) are the two main lesions. Early morphological aspects have been known for many years, but the use of computerized tomography (CT scan) and ultrasonography (US) through the anterior fontanelle have led to renewed interest and the general recognition of IVH. Localization, extent and frequency of the lesions can readily be established. However the early diagnosis of leukomalacia is still uncertain. Long survival, with mechanical ventilation of severely ill infants, has made it possible to follow the natural history of the lesions and has modified the relative frequency of their occurrence. Posthemorrhagic hydrocephalus, sclerosis of the centrum semiovale and multicystic encephalopathy are now commonly found at autopsy of infants who have survived for several weeks.