Relative Contributions of Ice Algae, Phytoplankton, and Benthic Microalgae to Primary Production in Nearshore Regions of the Beaufort Sea

Phytoplankton, ice algae, and benthic microalgae are the three sources of primary production in the western Beaufort Sea in winter and spring. Phytoplankton levels in winter are low with chlorophyll a levels near the limit of detection. Microflagellates are the most abundant organisms present in the water column along with a few diatoms. Low chlorophyll a, standing stock, and primary productivity continue into June when the ice breaks up. Cells are present in sea ice from the time it forms in the fall and are generally scattered throughout the ice thickness. Microflagellates are the most abundant organisms, but some diatoms, mostly pennate species, are also present. Cells concentrate in the bottom few cm of ice during March-April in response to increasing light levels. Growth continues until late May-early June when maximum production and standing stock occur. Benthic microalgal production was barely detectable in spring although chlorophyll a levels were high, perhaps left from the previous production season. Light is apparently the major factor controlling production in the spring, with the ice algae being able to take advantage of increasing light levels early in spring. This community shades both the water column and benthos so that production in those habitats does not increase until after the ice algae disappear in early June, but the ice community may be inhibited by layers of sediment in the ice. During this study, the ice algae provided about two-thirds and the phytoplankton one-third of the spring primary production; the benthic community contribution was negligible.Key words: western Beaufort Sea, phytoplankton, ice algae, benthic microalgae, primary productivity, chlorophyll a, standing stock, species present, environmental factorsMots clés: l'ouest de la mer de Beaufort, phytoplancton, algues glaciales, microalgues benthiques, productivité primaire, chlorophylle a, biomasse présente, facteurs du millie

Factors Hindering the Performance of Construction Project Managers

It has been said that the effective performance of the Project Manager (PM) is the single most critical factor affecting successful project outcomes. Little is known, however, of the nature and extent of the hindrances to PM effectiveness in the Construction Industry (CI). This paper reports on the results of a worldwide survey of PMs concerning these issues and shows that they have the potential to be more effective and more productive in their working. Associated with this is a need to be more aware of progress and developments in the CI generally, more aware of progress and developments in their own organisation, more delegation of contract administration tasks and more general administrative support. Also highlighted is the lengthy working hours of PMs

Phenotypic and molecular characterization of V-factor (NAD)-independent Haemophilus paragallinarum

In South Africa from early 1989, strains of Haemophilus paragallinarum not requiring nicotinamide adenine dinucleotide (NAD) have been isolated from commercial chickens suffering from infectious coryza. 15 of these field isolates were characterized by biochemical typing, serotyping, restriction endonuclease analysis (REA), and ribotyping. The isolates were chosen to represent diversity in geographic location, time of disease outbreak, and type of flock. All were typical of the species in biochemical properties, except that they were NAD-independent and all were Page serovar A. REA was performed with 3 enzymes: HindIII, HpaII, and SspI. All isolates gave identical REA profiles with all 3 enzymes. Ribotyping was performed using a probe that consisted of the plasmid pUC19 into which the 16s rRNA operon of H. paragallinarum had been inserted. All 15 isolates gave the same ribotyping profile using each of the 3 enzymes. As a group the NAD-independent strains gave REA profiles and ribotypes that were very different from a range of classic South African strains isolated before 1989. These results strongly suggest that the NAD-independent isolates are clonal in nature

Computed tomographic evaluation of the role of craniofacial and upper airway morphology in obstructive sleep apnea in Chinese

Objectives: To evaluate the relationship between cephalometric parameters, upper airway morphological factors and obstructive sleep apnea (OSA) in Chinese subjects. Design: Polysomnogram (PSG) were performed and scored using standard criteria. Supine lateral cephalometric parameters and pharyngeal cross-sectional areas at the level of velopharynx (VA) and hypopharynx (HA) were measured from computed tomographic scans. The roles of these parameters and other anthropometric/demographic characteristics in OSA (apnea hypopnea index, AHI≥5) and their relationship with severity of OSA were explored by multiple logistic and multi-nominal regression analysis. Results: Ninety-two subjects, ranging from normal (n = 36), mild/moderate OSA (n = 34) to severe OSA (n = 22), were evaluated. Compared with normal subjects, OSA subjects were heavier (body mass index 27 vs. 24kg/m2 ) and older (47 vs. 42 years of age); had smaller VA size and VA to HA ratio, lower positioned hyoid bone, longer and thicker soft palate, and more retropositioned mandible relative to maxilia. After controlling for body mass index and age, subjects with severe OSA (AHI>30) had more retropositioned mandible relative to maxilla (odds ratio, OR 1.31, P = 0.044) and longer soft palate (OR 1.16, P = 0.01), while those with mild/moderate OSA had larger VA to HA ratio (OR 0.17, P = 0.018). Conclusions: Craniofacial factors and upper airway morphology contributed to severity of OSA in Chinese subjects. Having controlled for obesity, more retropositioned mandible was associated with more severe OSA. © 2003 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Making the matrix matter:challenges in Australian grazing landscapes

Many ecological theories are based on the concept of patches. Patches are a useful starting point for conservation efforts, but a focus on patches alone will not always achieve desired conservation outcomes. Conservation strategies in the grazing landscapes of southeastern Australia suggest that large patches of trees are widely regarded as 'habitat' while other forms of habitat are largely ignored. We provide data on birds and reptiles from the Nanangroe grazing landscape that illustrate the potential habitat value of areas located between large patches of trees - that is, the matrix. Despite evidence on its potential value, present conservation strategies rarely consider the matrix. Possible reasons for this bias relate to the economics of farming and the history of land use, the current environmental law framework, and also the reluctance of ecologists to study the matrix. More scientific evidence on the role of the matrix will be crucial if conservation strategies are to consider not only patches, but entire landscapes. However, for science to be relevant to land management, there is a need for new research approaches. First, an increased consideration of environmental policy and law will increase the likelihood of scientific findings being adopted by policy makers. Second, at an applied level, more practical on-ground research into farming practices and clearer communication are necessary to achieve more sustainable matrix management in Australian grazing landscapes