We reasoned that if flow limitation plays an important role in lung hyperinflation, then bronchodilatation should be associated with a decrease of functional residual capacity (FRC) only in subjects breathing under conditions of flow limitation. This hypothesis was tested in 33 subjects with chronic airway narrowing due to asthma or chronic obstructive pulmonary disease (COPD). Flow limitation ...

A tidal bore is an abrupt rise in water depth advancing in some estuaries during spring tide conditions. In the present study, some detailed turbulence field measurements were conducted continuously at high-frequency (64 Hz) in the Garonne River tidal bore. The turbulent velocity components were sampled with an acoustic Doppler velocimeter (ADV) at 0.8 m beneath the freesurface. On 10 and 11 Se...

Experimental investigations were carried out in the Manchester Tidal flow Facility (MTF) to study the flow patterns in the region around and adjacent to a hypothetical headland in tidal (oscillatory) ambient flow. The Planar laser-induced fluorescence (PLIF) technique was used for visualization, with fluorescent dye released at specific points around the headland perimeter and in its adjacent r...

Measurements of tidal flow, volume, and oesophageal pressure were recorded on a group of 8 severely preterm infants with periodic respiration. Analysis of the flow trace for evidence of cardiac artefact, and the tidal volume trace to identify at what point of the tidal cycle apnoea starts, indicated that upper airways obstruction was associated with about half these attacks. It is surmised that...

A tidal bore is a natural and fragile phenomenon, which is of great importance for the ecology of an estuary. The bore development is closely linked with the tidal range and the river mouth shape, and its existence is sensitive to any small change in boundary conditions. Despite their ecological and cultural value, little is known on the flow field, turbulent mixing and sediment motion beneath ...

Existing research highlights that families face geographic, social, and psychological constraints that may limit the extent to which competition can take hold in school choice programs. In this paper, we address the implications of such findings by creating a network of student flows from 11 cohorts of eighth-grade students in the Chicago Public Schools (CPS). We applied a custom algorithm to g...

A tidal bore is a wall of water propagating upstream as the tidal flow turns to rising into an estuary with a tidal range larger than 5 to 6 m and the bathymetry that amplifies the tidal wave. The bore front is a shock characterised by a singularity of the free-surface and pressure and velocity fields. This study aims to characterise the impact of tidal bores on the turbulent dispersion of fish...

Lung function measurement is difficult in unsedated infants; tidal breathing parameters are a useful non-invasive surrogate, but even these measurements cause disturbance from applying a facemask. We investigated a novel volumetric vest system (FloRight), which measures volume changes of the respiratory system from changes in the magnetic fields induced by current-carrying coils around the enti...

The valve system in the mouth piece of two spacer devices was analysed. Pressures required to open and close the non-rebreathing valve were very low (less than 0.1 kPa). Inspiratory flow requirements were within physiological limits for infants' normal tidal breathing. Expiratory flow requirements varied significantly, and the flow required to prevent rebreathing from the chamber may exceed the...

OBJECTIVES To evaluate the effect of nebulized albuterol on tidal breathing flow-volume loops in infants with bronchiolitis due to respiratory syncytial virus. DESIGN A randomized, double-blind, control study. SETTING Pediatric unit in a community teaching hospital. PARTICIPANTS Twenty infants younger than 1 year of age (mean age, 5.8 +/- 2.8 months) with a first episode of wheezing due t...