Ammonia production by human faecal bacteria, and the enumeration, isolation and characterization of bacteria capable of growth on peptides and amino acids

DA - 20130125 IS - 1471-2180 (Electronic) IS - 1471-2180 (Linking) LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't SB - IMPeer reviewedPublisher PD

The Absolute Need for Creativity in Transport Planning

The transport planning process has often been characterised as consisting of a series of logical stages which lead towards the production of a final outcome. These stages include the identification of goals, the specification of alternatives, the collection of information, the modelling of alternative courses of action, the evaluation of alternatives, the selection of preferred alternatives, the implementation of these preferred alternatives and the monitoring of their consequences. While much attention has been paid to many of these processes, relatively little attention has focussed on the creative specification of alternatives.This paper seeks to show that there is an absolute need for creativity in the selection of alternative courses of action in transport planning. Drawing upon the techniques of creative thinking developed by Edward de Bono, the paper will show why creativity is needed and how all transport planners can improve their skills in Lateral Thinking. The paper will outline some fundamental ideas, and some myths, about creativity and describe three major techniques in creative thinking, namely the concept fan, random inputs, and the use of provocation. It will describe why and how these techniques work, and will then demonstrate their use in a range of transport planning applications

Behavioural Mechanisms of Non-Response in Mailback Travel Surveys

In the conduct of sample surveys in transport, there will inevitably be some level of non-response. The issues of non-response are fundamentally connected to the questions of reducing survey bias and increasing the accuracy of sample estimates. This is because non-respondents in sample surveys have often been shown to have significantly different characteristics from those of the respondents. These differences are in terms of the socio-demographic characteristics and, more importantly, in terms of travel behaviour characteristics. For example, non-respondents to household interview surveys tend to travel more than respondents to such surveys, because one of the main reasons for their non-response is that they are out of the house (travelling) when the interviewer calls to perform the interview. If due allowance is not made for this known difference, then estimates of total travel and travel distance will be under-estimated from such surveys. This will then result in under-estimates of emissions and fuel consumption in the survey area. Other types of non-response bias are associated with other types of survey method. This paper considers a range of issues associated with nonresponse to mailback travel surveys. It begins by reviewing some of the previous research on non-response in mailback travel surveys, in particular methods of correcting for this non-response. It then proposes a number of different behavioural mechanisms that might be associated with nonresponse patterns in those surveys, and suggests that previous methods of correcting for non-response in mailback travel surveys may be in error. The paper concludes by suggesting further steps that must be taken to fully understand the behavioural mechanisms underlying non-response in mailback travel surveys

Variability of copepod abundance and growth in the southern Benguela upwelling system and implications for the spawning of the Cape anchovy

Bibliography: pages 181-205.In the southern Benguela upwelling system, anchovy spawn serially between September and February each year. It has been suggested that this energy-intensive reproductive strategy requires continual ingestion of copepods, which dominate the diet of anchovy at this time. This thesis investigates the spatial and temporal variability of copepod abundance and growth, and their impact upon the spawning of anchovy. Sampling was conducted monthly between August-March 1993/94 and 1994/95 .. It is noteworthy that the primary spawning ground of anchovy, the western Agulhas Bank, had a significantly smaller biomass of copepods than the adjacent West Coast region. In terms of the growth rates of copepods, the effect of food-limitation on fecundity and somatic growth outweighed that of temperature

Are jellyfish increasing in response to ocean acidification?

Ocean acidification may negatively affect calcifying plankton, opening ecological space for noncalcifying species. Recently, a study of climate-forcing of jellyfish reported the first analysis suggesting that there were more jellyfish (generally considered a noncalcifying group)when conditions were more acidic (lower pH) from one area within the North Sea. We examine this suggestion for a number of areas in the North Sea and beyond in the Northeast Atlantic using coelenterate records from the Continuous Plankton Recorder and pH data from the International Council for the Exploration of the Sea for the period 1946–2003. We could find no significant relationships between jellyfish abundance and acidic conditions in any of the regions investigated. We conclude that the role of pH in structuring zooplankton communities in the North Sea and further afield at present is tenuous

Growth rates of copepods in the southern Benguela upwelling system: The interplay between body size and food

Copepod growth rates were estimated from shipboard measurements of egg production of adult female Calanus agulhensis, Calanoides carinatus, Nannocalanus minor, and Centropages brachiatus and molting rates of juvenile stages (N6-C5) of C. agulhensis. Data were obtained during austral spring and summer of 1989-1995 in the southern Benguela upwelling system. While maximum growth rates showed less than a threefold decline over the body-size range examined (525-2,763-mu m total length), probably owing to allometric considerations, mean growth rate decreased by one order of magnitude, suggesting limitation of growth rate by an environmental factor Most of this decline in mean growth rate was attributable to food limitation of large copepods. Frequency distributions of growth rate under low food densities were severely skewed toward slow growth rate for large copepods, whereas they were more symmetric for smaller copepods. In contrast, at high food concentrations, the frequency distributions had a high degree of symmetry for all copepods. These frequency distributions were interpreted in terms of a probabilistic model describing the encounter rate of copepods with suitably sized food particles. The effect of food limitation on growth rate was evaluated by regressing the coefficient of variation of growth rate against body size. A strong positive relationship was found (r(2) = 0.93, P < 0.001), indicating that small copepods were always sowing well, whereas the growth rate of large copepods was more variable. It is suggested that this difference is a consequence of the ability of small copepods to consume small particles, which are present at a relatively constant background density

Interpreting the Ionization Sequence in Star-Forming Galaxy Emission-Line Spectra

High ionization star forming (SF) galaxies are easily identified with strong emission line techniques such as the BPT diagram, and form an obvious ionization sequence on such diagrams. We use a locally optimally emitting cloud model to fit emission line ratios that constrain the excitation mechanism, spectral energy distribution, abundances and physical conditions along the star-formation ionization sequence. Our analysis takes advantage of the identification of a sample of pure star-forming galaxies, to define the ionization sequence, via mean field independent component analysis. Previous work has suggested that the major parameter controlling the ionization level in SF galaxies is the metallicity. Here we show that the observed SF- sequence could alternatively be interpreted primarily as a sequence in the distribution of the ionizing flux incident on gas spread throughout a galaxy. Metallicity variations remain necessary to model the SF-sequence, however, our best models indicate that galaxies with the highest and lowest observed ionization levels (outside the range -0.37 < log [O III]/H\b{eta} < -0.09) require the variation of an additional physical parameter other than metallicity, which we determine to be the distribution of ionizing flux in the galaxy.Comment: 41 pages, 17 figures, 9 tables, accepted to MNRA