Sleeping on a problem: the impact of sleep disturbance on intensive care patients - a clinical review

Sleep disturbance is commonly encountered amongst intensive care patients and has significant psychophysiological effects, which protract recovery and increases mortality. Bio-physiological monitoring of intensive care patients reveal alterations in sleep architecture, with reduced sleep quality and continuity. The etiological causes of sleep disturbance are considered to be multifactorial, although environmental stressors namely, noise, light and clinical care interactions have been frequently cited in both subjective and objective studies. As a result, interventions are targeted towards modifiable factors to ameliorate their impact. This paper reviews normal sleep physiology and the impact that sleep disturbance has on patient psychophysiological recovery, and the contribution that the clinical environment has on intensive care patients' sleep

Observations on the vertical structure of tidal and inertial currents in the central North Sea

Tidal and inertial current ellipses, measured at several locations and depths in the central North Sea during a number of monthly periods in 1980, 1981 and 1982, are decomposed into counterrotating, circular components to which Ekman dynamics are applied to determine Ekman layer depths and vertical phase differences, from which are inferred overall values of the eddy viscosity and drag coefficient. Stratification effects produce an additional vertical phase shift of the anticyclonic rotary component, indicative of an inverse proportionality of the eddy viscosity to the vertical density gradient. From the time variations of the Ekman layer depths of the semidiurnal tidal components, as well as from the vertical structure of the inertial current component, we infer variations in the relative vorticity of the low-frequency flow

Internal Wave Turbulence Near a Texel Beach

A summer bather entering a calm sea from the beach may sense alternating warm and cold water. This can be felt when moving forward into the sea (‘vertically homogeneous’ and ‘horizontally different’), but also when standing still between one’s feet and body (‘vertically different’). On a calm summer-day, an array of high-precision sensors has measured fast temperature-changes up to 1°C near a Texel-island (NL) beach. The measurements show that sensed variations are in fact internal waves, fronts and turbulence, supported in part by vertical stable stratification in density (temperature). Such motions are common in the deep ocean, but generally not in shallow seas where turbulent mixing is expected strong enough to homogenize. The internal beach-waves have amplitudes ten-times larger than those of the small surface wind waves. Quantifying their turbulent mixing gives diffusivity estimates of 10−4–10−3 m2 s−1, which are larger than found in open-ocean but smaller than wave breaking above deep sloping topography

Do plant species influence soil gas fluxes in tropical forests?

Abstract ID: 53. Publicado também on-line

Detailed observations of the phytoplankton spring bloom in the stratifying central North Sea

Analysis of detailed time series of bio-optical and temperature data from the North Sea supports the view that a minimum level of turbulence is a prerequisite for the onset and maintenance of the phytoplankton spring bloom in shelf seas, which distinguishes these seas from the open ocean. The start of the spring bloom, primarily diatoms, is controlled by the light regime, while its progress is predominantly dependent upon episodic turbulence input following short periods of stratification, which allow the resuspension of a fast sinking (50-200 m day-1) phytoplankton community from the bottom mixing layer. A relationship between turbulence and the vertical distribution of phytoplankton is proposed which is found at synoptic time scales and on time scales of a day and less. Throughout the spring bloom, algal biomass is either equally distributed through the water column or concentrated in the bottom mixing layer. Growth can only be sustained in the near-surface layer during periods of substantial turbulence input. The establishment of semi-permanent seasonal stratification causes an almost complete reduction in near-surface biomass and a concomitant increase in biomass in the bottom mixing layer which subsequently acts as a source for occasional increased near-surface biomass until early summer

Internal wave breaking near the foot of a steep East-Pacific continental slope

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in van Haren, H., Voet, G., Alford, M., & Torres, D. Internal wave breaking near the foot of a steep East-Pacific continental slope. Progress In Oceanography, 205, (2022): 102817, https://doi.org/10.1016/j.pocean.2022.102817.The sloping sides of ocean basins are of particular interest for their potential importance for considerable turbulence generation via internal wave breaking and associated water circulation. The difference with the ocean interior may be manifest in a 10–100 m relatively thin layer above the seafloor. We set up an observational study with high-resolution stand-alone instrumentation attached to a custom-made release-anchor frame sampling to within 0.5 m from the seafloor up to 150 m above it. For two months, the taut wire moored instrumentation was tested in 1100 m water depth of the East-Pacific, off the coast of San Diego (CA, USA). The mooring was oceanward of an underwater bank and near the foot of its steep but gentle two-dimensional slope. Temperature sensor data demonstrate that internal waves peak at semidiurnal frequencies. While short (<1 h) periods show complicated structure, tidally averaged turbulence dissipation rate monotonically increases towards the seafloor over two orders of magnitude. The largest turbulence dissipation rates are observed during the relatively warm phase of an internal wave. Although the local topographic slope is supercritical for semidiurnal internal waves, turbulent bores propagating up the slope and hydraulic jumps are not observed. Most of the turbulence appears to be dominated by shear production, but not related to steady frictional flow near the seafloor.This work has been partially funded from NSF-grant OCE-1756264

Measuring soccer players’ contributions to chance creation by valuing their passes

Scouting departments at soccer clubs aim to discover players having a positive influence on the outcomes of matches. Since passes are the most frequently occurring on-the-ball actions on the pitch, a natural way to achieve this objective is by identifying players who are effective in setting up chances. Unfortunately, traditional statistics such as number of assists fail to reveal players excelling in this area. To overcome this limitation, this paper introduces a novel metric that measures the players’ involvement in setting up chances by valuing the effectiveness of their passes. Our proposed metric identifies Arsenal player Mesut Özil as the most impactful player in terms of passes during the 2017/2018 season and proposes Ajax player Frenkie de Jong as a suitable replacement for Andrés Iniesta at FC Barcelona