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

The impacts of withdrawal and replacement of general practitioner services on aeromedical service trends: A 13-year interrupted time-series study in Tennant Creek, Northern Territory

Background: The Royal Flying Doctor Service, RFDS, provides aeromedical care to patients during fixed-wing transport over vast distances to healthcare unavailable in rural or remote communities. This study examined the relationship between changes in local accessibility to primary healthcare services and rates of aeromedical service use over time. Methods: This was a, 13-year interrupted time-series study (1999–2012) in Tennant Creek, Northern Territory. Quarterly aeromedical service use for primary care sensitive conditions were calculated and exposure to general practice, GP, services was characterised over time with events modelled as intervention variables, a, GP service withdrawal, Nov- 2004, and (b,) GP service replacement, Dec2006, . Intervention effects were estimated using PROC ARIMA in SAS after examination of the time-series structure. Results GP withdrawal resulted in an immediate and sustained doubling in quarterly aeromedical service use (+11.8 services per quarter) services per quarter, and GP service replacement had no significant effect. Discussion: Large and immediate increases in aeromedical service use result from the loss of local GP services yet, in this case, replacement with a new GP service, 2-years hence, did not ameliorate that effect after six years. Conclusions: These findings demonstrate the immediate impact of GP-service loss on the rates of aeromedical transfer of patients from this remote community and lend caution to expectations about the timeline over which newly implemented primary health care services in such contexts can mitigate the impact of such a loss.Matthew T. Haren, John Setchell, David L. John and Mark Danie

Do plant species influence soil gas fluxes in tropical forests?

Abstract ID: 53. Publicado também on-line

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

Fluxes and distribution of dissolved iron in the eastern (sub-) tropical North Atlantic Ocean

Aeolian dust transport from the Saharan/Sahel desert regions is considered the dominant external input of iron (Fe) to the surface waters of the eastern (sub-) tropical North Atlantic Ocean. To test this hypothesis, we investigated the sources of dissolved Fe (DFe) and quantified DFe fluxes to the surface ocean in this region. In winter 2008, surface water DFe concentrations varied between <0.1 nM and 0.37 nM, with an average of 0.13 ± 0.07 nM DFe (n = 194). A strong correlation between mixed layer averaged concentrations of dissolved aluminum (DAl), a proxy for dust input, and DFe indicated dust as a source of DFe to the surface ocean. The importance of Aeolian nutrient input was further confirmed by an increase of 0.1 nM DFe and 0.05 ?M phosphate during a repeat transect before and after a dust event. An exponential decrease of DFe with increasing distance from the African continent, suggested that continental shelf waters were a source of DFe to the northern part of our study area. Relatively high Fe:C ratios of up to 3 × 10?5 (C derived from apparent oxygen utilization (AOU)) indicated an external source of Fe to these African continental shelf waters. Below the wind mixed layer along 12°N, enhanced DFe concentrations (>1.5 nM) correlated positively with apparent oxygen utilization (AOU) and showed the importance of organic matter remineralization as an DFe source. As a consequence, vertical diffusive mixing formed an important Fe flux to the surface ocean in this region, even surpassing that of a major dust event

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