Temporal Variation In The Carrying Capacity Of A Perennial Grass Population

Density dependence and, therefore, K (carrying capacity, equilibrium population size) are central to understanding and predicting changes in population size (N). Although resource levels certainly fluctuate, K has almost always been treated as constant in both theoretical and empirical studies. We quantified temporal variation in K by fitting extensions of standard population dynamic models to 16 annual censuses of a population of the perennial bunch-grass Bouteloua rigidiseta. Variable-K models provided substantially better fits to the data than did models that varied the potential rate of population increase. The distribution of estimated values of K was skewed, with a long right tail (i.e., a few >jackpot> years). The population did not track K closely. Relatively slow responses to changes in K combined with large, rapid changes in K sometimes caused N to be far from K. In 13%-20% of annual intervals, K was so much larger than N that the population's dynamics were best described by geometric growth and the population was, in effect, unregulated. Explicitly incorporating temporal variation in K substantially improved the realism of models with little increase in model complexity and provided novel information about this population's dynamics. Similar methods would be applicable to many other data sets.Integrative Biolog

Economics of organic farming (extension to OF0125)(0F0190)

This project OF0190 was an extension to OF0125 to cover completing the comparison data for 1997/98 and to extend the data collection by one further year (1998/99). The final reports for the two projects are therefore being submitted jointly. The OF0125 report covers the period 1995/96-1997/98, for which a detailed report was submitted to MAFF in July 1999, and a revised detailed report including a complete set of comparisons with conventional farms was submitted to MAFF, after revisions, in July 2000. That report has now been published at www.organic.aber.ac.uk/library/organic farm incomes.pdf. A detailed report for 1998/99 has been submitted to MAFF in March 2001, and will be published at the same internet site once accepted. The report presents results from research work carried out for the Ministry of Agriculture, Fisheries and Food (MAFF) on the financial performance of organic farms in 1998/99. The aim of the research was to assess the financial performance of organic farms differentiated by farm type, in order to inform MAFF policy-making with respect to organic farming, and to provide a basis for assessments by farmers, advisers and other interested parties of the farm-level implications of conversion to and continued organic farming. To provide an idea of the trends over time, where possible data for continuous samples of farms are presented for 1997/98 and 1998/99. The specific objectives were to extend the previous project (OF0125, covering 1995/96 to 1997/98) to collect and collate data on the financial performance of organic farms, differentiated by farm type . This was achieved through the collation of financial data collected under three different MAFF-funded research projects supplemented by data collected on other farm types. The samples of organic farms are small because of the limited number of organic holdings over 8 ESU (European Size Units) with identifiable holding numbers in 1996, when the previous study was started. As the sample is small there is limitation on how the results may be extrapolated to the wider population of organic farms, especially as the structure and objectives of those converting to organic production in the late 1990s may be different from those that converted in the 1970s and 1980s. Detailed financial input, output, income, liabilities and assets and some physical performance measures are presented for 1998/99. Where an identical sample of five farms is available, data are presented for 1997/98 and 1998/99 for the sample. The organic farm samples are so small that outliers (especially larger farms) have a large influence on the average. If the samples were larger, general trends would be more apparent and less influenced by individual farms; despite this, some explanation has been attempted of trends and changes in inputs, outputs and incomes. However, great care must be taken in extrapolating results. Of those farm types for which a continuous identical sample of five farms was available, Net Farm Incomes (NFI) increased for cropping (£281/ha) and dairy farms (£487/ha) in 1998/99 compared with 1997/98; in both cases outputs as well as inputs increased between years. Mixed farms showed an average reduction in outputs and increase in inputs, lowering the average NFI to £15/ha in 1998/99. The five lowland cattle and sheep farms improved a negative NFI of £161/ha in 1997/98 to a positive £7/ha in 1998/99 through an increase in livestock outputs with a similar level of inputs to that of 1997/98. Due to the high level of farmer and spouse labour on horticultural holdings, the average Management and Investment Income (MII) of the sample was negative, but the average NFI was £1,836/ha. On four holdings, 1998/99 average outputs were 92%, and inputs were 97% of the previous year, resulting in an average NFI in 1998/99 for that group of 75% of the 1997/98 result. The group of LFA farms, consisting of four cattle and sheep and one mixed farm, achieved an average NFI of £72/ha in 1998/99

Examining the relationship between leaders' power use, followers' motivational outlooks, and followers' work intentions

From the foundation of self-determination theory and existing literature on forms of power, we empirically explored relationships between followers' perceptions of their leader's use of various forms of power, followers' self-reported motivational outlooks, and followers' favorable work intentions. Using survey data collected from two studies of working professionals, we apply path analysis and hierarchical multiple regression to analyze variance among constructs of interest. We found that followers' perceptions of hard power use by their leaders (i.e., reward, coercive, and legitimate power) was often related to higher levels of sub-optimal motivation in followers (i.e., amotivation, external regulation, and introjected regulation). However, followers who perceived their leaders used soft power (i.e., expert, referent, and informational power) often experienced higher levels of optimal motivation (i.e., identified regulation and intrinsic motivation), but further investigation of soft power use is warranted. The quality of followers' motivational outlooks was also related to intentions to perform favorably for their organizations.Published versio

Surface Code Threshold in the Presence of Correlated Errors

We study the fidelity of the surface code in the presence of correlated errors induced by the coupling of physical qubits to a bosonic environment. By mapping the time evolution of the system after one quantum error correction cycle onto a statistical spin model, we show that the existence of an error threshold is related to the appearance of an order-disorder phase transition in the statistical model in the thermodynamic limit. This allows us to relate the error threshold to bath parameters and to the spatial range of the correlated errors.Comment: 5 pages, 2 figure

Subglacial floods beneath ice sheets.

Subglacial floods (jökulhlaups) are well documented as occurring beneath present day glaciers and ice caps. In addition, it is known that massive floods have occurred from ice-dammed lakes proximal to the Laurentide ice sheet during the last ice age, and it has been suggested that at least one such flood below the waning ice sheet was responsible for a dramatic cooling event some 8000 years ago. We propose that drainage of lakes from beneath ice sheets will generally occur in a time-periodic fashion, and that such floods can be of severe magnitude. Such hydraulic eruptions are likely to have caused severe climatic disturbances in the past, and may well do so in the future

The conceptus induces a switch in protein expression and activities of superoxide dismutase 1 and 2 in the sheep endometrium during early pregnancy

Acknowledgements We thank Philippe Bolifraud (INRA, France), Krawiec Angele, Sandra Grange, Laurence Puillet-Anselme (CHU Grenoble, France) and Margaret Fraser (Aberdeen, UK) for their expert technical assistance. The authors also thank the staff of the sheep sheds of Jouy-en-Josas (INRA, France). The authors would also like to thank the anonymous reviewers for their close examination of this article and their useful comments. Funding This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.Peer reviewedPostprin

Adult Adoption: A New Legal Tool for Lesbians and Gay Men

This Comment explores the current statutory framework for adult adoption, the parameters of the legal relationship created, and the scope of the right to privacy issues involved in the exercise of this statutory right. In addition, possible motives individuals may have for utilizing adult adoption, the need for attorneys to identify potential problem areas for their clients, and the potential disadvantages of such a legal relationship, particularly with respect to the dynamics of the individuals\u27 relationship, are discussed