Photobiology of sea ice algae during initial spring growth in Kangerlussuaq, West Greenland: insights from imaging variable chlorophyll fluorescence of ice cores.

We undertook a series of measurements of photophysiological parameters of sea ice algae over 12 days of early spring growth in a West Greenland Fjord, by variable chlorophyll fluorescence imaging. Imaging of the ice-water interface showed the development of ice algae in 0.3-0.4 mm wide brine channels between laminar ice crystals in the lower 4-6 mm of the ice, with a several-fold spatial variation in inferred biomass on cm scales. The maximum quantum yield of photosynthesis, F(v) /F(m), was initially low (~0.1), though this increased rapidly to ~0.5 by day 6. Day 6 also saw the onset of biomass increase, the cessation of ice growth and the time at which brine had reached <50 psu and >-2 °C. We interpret this as indicating that the establishment of stable brine channels at close to ambient salinity was required to trigger photosynthetically active populations. Maximum relative electron transport rate (rETR(max)), saturation irradiance (E(k)) and photosynthetic efficiency (α) had also stabilised by day 6 at 5-6 relative units, ~30 µmol photons m⁻² s⁻¹ and 0.4-0.5 µmol photons m⁻²s⁻¹, respectively. E(k) was consistent with under-ice irradiance, which peaked at a similar value, confirming that daytime irradiance was adequate to facilitate photosynthetic activity throughout the study period. Photosynthetic parameters showed no substantial differences with depth within the ice, nor variation between cores or brine channels suggesting that during this early phase of ice algal growth cells were unaffected by gradients of environmental conditions within the ice. Variable chlorophyll fluorescence imaging offers a tool to determine how this situation may change over time and as brine channels and algal populations evolve.

Pressure ulcer prevention in nursing homes: views and beliefs of enrolled nurses and other health care workers.

UNLABELLED: BACKGROUND In the Netherlands much attention has been paid to pressure ulcer prevention. National guidelines on pressure ulcer prevention were developed in 1985 and adapted in 1992 at the request of a national organization for quality assurance in health care. Several studies indicate that nurses seem to be insufficiently informed about pressure ulcer preventive activities. There is, however, no information available about the reasons why nurses seem to be insufficiently informed. AIMS AND OBJECTIVES: This study was planned to elucidate the views and beliefs of health care workers (especially enrolled nurses) in Dutch nursing homes about pressure ulcer prevention and about issues related with pressure ulcer prevention. DESIGN: A qualitative study with semi-structured, tape-recorded interviews. METHOD: Interviews were conducted with enrolled nurses, team leaders, head nurses, staff nurses and physicians. The interviews were coded and analysed. RESULTS: Analysis of the interviews revealed that today's pressure ulcer preventive activities are very much based on old traditions in nursing. It also showed that enrolled nurses have no intention to change the care they deliver with regard to pressure ulcer prevention. CONCLUSIONS: It is concluded that a systematic approach is necessary to change nursing thinking and acting with regard to pressure ulcer prevention. RELEVANCE TO CLINICAL PRACTICE: This study gives an overview of the views and beliefs of health care workers (especially enrolled nurses) in Dutch nursing homes about pressure ulcer prevention. These views and beliefs can be used as a starting point for effective implementation of guidelines regarding the prevention of pressure ulcers.