ALBERT

Notes: Finite-difference fluid-dynamics modeling has been used to predict deposition rates, fractional amounts of phases, and deposition morphology for the codeposition of silicon carbide and pyrolitic carbon from tetramethylsilane via laser-induced chemical vapor deposition (LCVD). Calculated results agree fairly well with rod deposition experiments. The morphologic features of rods that have been grown using LCVD are examined and explained using the results of the finite-difference calculations.

Notes: The reliance of traditional job analysis on job incumbents as the primary source of work-analytic data is critically examined. It is argued that the sole use of incumbents is practically and theoretically unjustified. The incorporation of non-incumbents to the work analysis process is advocated, especially when abstract human attributes and strategic requirements are evaluated. The time and resource savings afforded by the use of mechanical estimation of work dimensions are also discussed. A revision of traditional formats of data collection in job analysis such as paper-and-pencil surveys and face-to-face interviews is proposed. Instead, the potential work-analytic uses of electronic records of work information nowadays available in electronic performance monitoring systems are outlined.

Notes: 1. The inter- and intra-annual changes in the biomass, elemental (carbon (C), nitrogen (N) and phosphorus (P)) and taxonomical composition of the phytoplankton in a high mountain lake in Spain were studied during 3 years with different physical (fluctuating hydrological regime) and chemical conditions. The importance of internal and external sources of P to the phytoplankton was estimated as the amount of P supplied via zooplankton recycling (internal) or through ice-melting and atmospheric deposition (external).2. Inter-annual differences in phytoplankton biomass were associated with temperature and total dissolved phosphorus. In 1995, phytoplankton biomass was positively correlated with total dissolved phosphorus. In contrast, the negative relationship between zooplankton and seston biomass (direct predatory effects) and the positive relationship between zooplankton P excretion and phytoplankton biomass in 1997 (indirect P-recycling effects), reinforces the primary role of zooplankton in regulating the total biomass of phytoplankton but, at the same time, encouraging its growth via P-recycling.3. Year-to-year variations in seston C : P and N : P ratios exceeded intra-annual variations. The C : P and N : P ratios were high in 1995, indicating strong P limitation. In contrast, in 1996 and 1997, these ratios were low during ice-out (C : P 〈 100 and N : P 〈 10) and increased markedly as the season progressed. Atmospheric P load to the lake was responsible for the decline in C : P and N : P ratios.4. Intra-annual variations in zooplankton stoichiometry were more pronounced than the overall differences between 1995 and 1996. Thus, the zooplankton N : P ratio ranged from 6.9 to 40.1 (mean 21.4) in 1995, and from 10.4 to 42.2 (mean 24.9) in 1996. The zooplankton N : P ratio tended to be low after ice-out, when the zooplankton community was dominated by copepod nauplii, and high towards mid- and late-season, when these were replaced by copepodites and adults.5. In 1995, the minimum demands for P of phytoplankton were satisfied by ice-melting, atmospheric loading and zooplankton recycling over 100%. In order of importance, atmospheric inputs (〉 1000%), zooplankton recycling (9–542%), and ice-melting processes (0.37–5.16%) satisfied the minimum demand for P of phytoplankton during 1996 and 1997. Although the effect of external forces was rather sporadic and unpredictable in comparison with biologically driven recycle processes, both may affect phytoplankton structure and elemental composition.6. We identified three conceptual models representing the seasonal phosphorus flux among the major compartments of the pelagic zone. While ice-melting processes dominated the nutrient flow at the thaw, biologically driven processes such as zooplankton recycling became relevant as the season and zooplankton ontogeny progressed. The stochastic nature of P inputs associated with atmospheric events can promote rapid transitional changes between a community limited by internal recycling and one regulated by external load.7. The elemental composition of the zooplankton explains changes in phytoplankton taxonomic and elemental composition. The elemental negative balance (seston N : P 〈 zooplankton N : P, low N : P recycled) during the thaw, would promote a community dominated by species with a high demand for P (Cryptophyceae). The shift to an elemental positive balance (seston N : P 〉 zooplankton N : P, high N : P recycled) in mid-season would skew the N : P ratio of the recycled nutrients, favouring dominance by chrysophytes. The return to negative balance, as a consequence of the ontogenetic increase in zooplankton N : P ratio and the external P inputs towards the end of the ice-free season, could alleviate the limitation of P and account for the appearance of other phytoplankton classes (Chlorophyceae or Dinophyceae).

Notes: The mutT, mutM, and mutY genes of the GO system of the Pseudomonas aeruginosa PAO1 strain have been characterized by cloning, sequencing, and complementation analysis. The three genes, when cloned in a plasmid, were able to complement the high mutation frequency of the corresponding Escherichia coli deficient strains. Our results demonstrate that the putative mutT, mutM, and mutY gene products from P. aeruginosa are able to perform the expected activity. In addition, the sequence of the P. aeruginosa mutT gene strongly suggested that the product of this gene has a bifunctional activity in P. aeruginosa, being the C-terminal part 40% identical to a consensus sequence of thiamine monophosphate synthases. Our results also demonstrated that the N-terminal part of the protein is necessary and sufficient for the 8-oxodGTP hydrolase activity.

Notes: Mini-transposon is the generic name given to the members of a collection of genetic assets derived from transposons Tn10 and Tn5, in which the naturally occurring functional segments of DNA have been rearranged artificially to originate shorter mobile elements. In the most widespread design (that known as the pUT system), any heterologous DNA segment can be conveniently cloned within the boundaries of a mini-Tn5 vector and finally inserted into the chromosome of target Gram-negative bacteria after a few simple genetic manipulations. The large variety of antibiotic, non-antibiotic and excisable selection markers available has been combined at ease with DNA fragments encoding one or more phenotypes of interest for ecological or biotechnological applications. These include the tagging of specific strains in a community with selectable and/or optical marker genes, the production of stable gene fusions for monitoring transcriptional regulation in single cells, the metabolic engineering of strains destined for bioremediation, the non-disruptive monitoring of gene transfer and the assembly of gene containment and strain containment circuits for genetically manipulated microorganisms.

Notes: Summary Nest-site selection and breeding success was studied in a breeding population of Roller (Coracias garrulus) in the Southwest of Spain. 567 nest-boxes were installed on electric pylons in seven different habitats: fallow land, cereals, holm oaks, olive groves, pasture land, irrigated crops (rice and maize) and shrubs. The more favoured habitats were the irrigated crops, the olive groves and the holm-oaks, while only the cereals were clearly avoided. Fallow land, pastures and shrublands were preferred approximately according to their availability in the area. The mean laying date of Rollers was significantly different between habitats, however, the other reproductive variables did not vary with habitat type. The seasonal trend in reproductive value of the Roller varied relative to habitat type. So, in olive groves and irrigated crops no clear seasonal trends were detected in clutch size, while a clear seasonal decline in clutch size was detected in the rest of the habitat types. The intensity of selection of each habitat was only marginally related to the hatching success of the rollers in Extremadura. These results indicate that the decrease in natural nest-sites as a result of the intensification of agriculture is the principal cause of the decline in Roller populations in contrast to previous studies which argued that this was a consequence of the decrease in available food.