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T F Pedersen

Publications and source records attributed to T F Pedersen.

6 recordsLinked to original sources
PubMed2005

Glacial/interglacial changes in subarctic north pacific stratification.

Since the first evidence of low algal productivity during ice ages in the Antarctic Zone of the Southern Ocean was discovered, there has been debate as to whether it was associated with increased polar ocean stratification or with sea-ice cover, shortening the productive season. The sediment concentration of biogenic barium at Ocean Drilling Program site 882 indicates low algal productivity during ice ages in the Subarctic North Pacific as well. Site 882 is located southeast of the summer sea-ice extent even during glacial maxima, ruling out sea-ice-driven light limitation and supporting stratification as the explanation, with implications for the glacial cycles of atmospheric carbon dioxide concentration.

Journal Article↗
PubMed1997

Gas compression in lungs decreases peak expiratory flow depending on resistance of peak flowmeter.

It has recently been shown (O. F. Pedersen T. R. Rasmussen, O. Omland, T. Sigsgaard, P. H. Quanjer. and M. R. Miller. Eur. Respir. J. 9: 828-833, 1996) that the added resistance of a mini-Wright peak flowmeter decreases peak expiratory flow (PEF) by approximately 8% compared with PEF measured by a pneumotachograph. To explore the reason for this, 10 healthy men (mean age 43 yr, range 33-58 yr) were examined in a body plethysmograph with facilities to measure mouth flow vs. expired volume as well as the change in thoracic gas volume (Vb) and alveolar pressure (PA). The subjects performed forced vital capacity maneuvers through orifices of different sizes and also a mini-Wright peak flowmeter. PEF with the meter and other added resistances were achieved when flow reached the perimeter of the flow-Vb curves. The mini-Wright PEF meter decreased PEF from 11.4 +/- 1.5 to 10.3 +/- 1.4 (SD) l/s (P < 0.001), PA increased from 6.7 +/- 1.9 to 9.3 +/- 2.7 kPa (P < 0.001), an increase equal to the pressure drop across the meter, and caused Vb at PEF to decrease by 0.24 +/- 0.09 liter (P < 0.001). We conclude that PEF obtained with an added resistance like a mini-Wright PEF meter is a wave-speed-determined maximal flow, but the added resistance causes gas compression because of increased PA at PEF. Therefore, Vb at PEF and, accordingly, PEF decrease.

Adult↗
PubMed1993

[Calcium blood changes in septic conditions. A review].

Hypocalcemia has been reported in critically ill patients over the last 10-15 years, however, measurements of Ca2+ in blood have not yet became routine in the treatment of severely ill patients. In order to stress the importance of calcium in such patients, a review of calcium changes in septic conditions is presented. In vitro studies show that the intracellular calcium metabolism is disturbed in these patients, and that the changes in extracellular calcium are probably secondary to the intracellular changes. Parathyroid hormone secretion is inappropriate in septic patients. The reason for this is unknown. Administration of calcium parenterally does not seem to affect the prognosis, however calcium seems to be beneficial in patients with hypotension. Since the level of Ca2+ in blood may have prognostic significance in septic patients, measurements of Ca2+ in blood should be used routinely in these patients, in order to point out "risk" patients as early as possible.

Calcium↗
PubMed1989

On the natural enrichment of cadmium and molybdenum in the sediments of Ucluelet Inlet, British Columbia.

Cadmium concentrations in Ucluelet Inlet sediments are usually high compared with most marine environments, ranging up to 8 micrograms g-1. The distribution of the element is closely correlated with Mo, organic carbon and total nitrogen in depth profiles at three stations. Paradoxically, organic carbon concentrations are high in inlet sediments, reaching up to 9 wt.%, although the sedimentation rate determined from 210Pb measurements is low at all three sites (less than 0.03 to 0.28 cm year-1). C:N ratio data indicate a mixed marine-terrigenous provenance for the organic material and a relatively recent increase in the terrigenous proportion which probably represents wood debris associated with logging and log booming activity in the area. The complete absence of Mn enrichments in surface sediments, coupled with qualitative observations that H2S is present at very shallow depths, strongly suggest that the deposits are anoxic very near the sediment-water interface. The Cd and Mo enrichments are not due to anthropogenic inputs but are instead ascribed to diffusion of the dissolved metals from overlying seawater into the slowly-accumulating, organic-rich, anoxic sediments and their fixation in the solid phase as CdS and as a coprecipitate with FeS, respectively.

British Columbia↗