Comparison of preferences for object properties in the rat using paired- and free-choice paradigms

A common method for testing preference for objects is to determine which of a pair of objects is approached first in a paired-choice paradigm. In comparison, many studies of preference for environmental enrichment (EE) devices have used paradigms in which total time spent with each of a pair of objects is used to determine preference. While each of these paradigms gives a specific measure of the preference for one object in comparison to another, neither method allows comparisons between multiple objects simultaneously. Since it is possible that several EE objects would be placed in a cage together to improve animal welfare, it is important to determine measures for rats' preferences in conditions that mimic this potential home cage environment. While it would be predicted that each type of measure would produce similar rankings of objects, this has never been tested empirically. In this study, we compared two paradigms: EE objects were either presented in pairs (paired-choice comparison) or four objects were presented simultaneously (simultaneous presentation comparison). We used frequency of first interaction and time spent with each object to rank the objects in the paired-choice experiment, and time spent with each object to rank the objects in the simultaneous presentation experiment. We also considered the behaviours elicited by the objects to determine if these might be contributing to object preference. We demonstrated that object ranking based on time spent with objects from the paired-choice experiment predicted object ranking in the simultaneous presentation experiment. Additionally, we confirmed that behaviours elicited were an important determinant of time spent with an object. This provides convergent evidence that both paired choice and simultaneous comparisons provide valid measures of preference for EE objects in rats. (C) 2007 Elsevier B.V. All rights reserved.

The relationship between multi-species catch and effort: among fishery comparisons

The control of fishing mortality via fishing effort remains fundamental to most fisheries management strategies even at the local community or co-management level. Decisions to support such strategies require knowledge of the underlying response of the catch to changes in effort. Even under adaptive management strategies, imprecise knowledge of the response is likely to help accelerate the adaptive learning process. Data and institutional capacity requirements to employ multi-species biomass dynamics and age-structured models invariably render their use impractical particularly in less developed regions of the world. Surplus production models fitted to catch and effort data aggregated across all species offer viable alternatives. The current paper seeks models of this type that best describe the multi-species catch–effort responses in floodplain-rivers, lakes and reservoirs and reef-based fisheries based upon among fishery comparisons, building on earlier work. Three alternative surplus production models were fitted to estimates of catch per unit area (CPUA) and fisher density for 258 fisheries in Africa, Asia and South America. In all cases examined, the best or equal best fitting model was the Fox type, explaining up to 90% of the variation in CPUA. For lake and reservoir fisheries in Africa and Asia, the Schaefer and an asymptotic model fitted equally well. The Fox model estimates of fisher density (fishers km−2) at maximum yield (iMY) for floodplain-rivers, African lakes and reservoirs and reef-based fisheries are 13.7 (95% CI [11.8, 16.4]); 27.8 (95% CI [17.5, 66.7]) and 643 (95% CI [459,1075]), respectively and compare well with earlier estimates. Corresponding estimates of maximum yield are also given. The significantly higher value of iMY for reef-based fisheries compared to estimates for rivers and lakes reflects the use of a different measure of fisher density based upon human population size estimates. The models predict that maximum yield is achieved at a higher fishing intensity in Asian lakes compared to those in Africa. This may reflect the common practice in Asia of stocking lakes to augment natural recruitment. Because of the equilibrium assumptions underlying the models, all the estimates of maximum yield and corresponding levels of effort should be treated with caution.

Active control comparisons: the ideal trial design

This report describes the concept for a clinical trial that uses carbamazepine as the gold-standard active control for a study of newly diagnosed patients. The authors describe an endpoint including efficacy and tolerability, and a stopping rule that uses a series of interim analyses in order to reach a conclusion as efficiently as possible without sacrificing reliability.

Molecular comparisons of the Culex pipiens (L.) complex esterase gene amplicons

The amplification of carboxylesterase genes is a mechanism of organophosphate resistance in Culex mosquitoes. Amplified carboxylesterase genes from an insecticide resistant Culex pipiens strain collected in Cyprus were analysed and compared to other Culex amplified carboxylesterase alleles. A 12 kb section of genomic DNA containing two gene loci coding for carboxylesterase alleles A5 and B5 was cloned and sequenced. A comparison between this amplicon and one from a strain with co-amplified carboxylesterase alleles A2 and B2 revealed a number of differences. The intergenic spacer was 3.7 kb in length in the A5-B5 amplicon (2.7 kb in A2-B2) and contained putative Juan and transposable elements upstream of B5. A fragment of a gene with high homology to aldehyde oxidase was also present immediately downstream of A5. The comparison revealed no differences that would explain the successful spread of the A2-B2 amplicon worldwide whilst the A5-B5 amplicon is restricted to the Mediterranean. (C) 2004 Elsevier Ltd. All rights reserved.

Comparisons between the in vitro and in vivo efficacies of potential fungal antagonists of Armillaria mellea

Seventeen fungal isolates were tested in vitro as potential antagonists of two isolates of the root rot pathogen, Armillaria mellea. Some of the isolates were also added on mushroom composts with living mycelia to the roots of Armillaria-inoculated potted strawberry plants in the glasshouse to find out if they had the same degree of efficacy against the disease. Dactylium dendroides isolate SP was the most effective in reducing mycelial growth of A. mellea isolate 1 (Am1), followed by Trichoderma harzianum isolate Th2 and T. viride isolate Tv4. Th2, Th22, Tv3 and SP grew extensively over Am1 colonies, disintegrating the rhizomorphs. Isolate Tham1 of T hamatum was the most effective in reducing mycelial growth of A. mellea isolate 2 (Am2), followed by Tv3. Th12, Th22, Tv1, Tv3 and SP inhibited the initiation and growth of rhizomorphs of Am2. Regeneration tests showed that both Am1 and Am2 attacked by Trichoderma isolates and SP were no longer viable. Th23 and SP were almost as effective in vivo as in vitro. But isolate Co of Chaetomium olivaceum, which was ineffective in vitro, was found effective in vivo. Conversely, Th2, which exhibited good antagonistic activity in vitro, performed poorly in vivo. These results show that the in vitro and in vivo efficacies of potential antagonists may not necessarily be closely correlated. Hence, there is a danger that potentially effective isolates may be discarded if decisions are made only on the basis of preliminary screening tests carried out under laboratory conditions.

Anterior cingulate activity and level of cognitive conflict: explicit comparisons

The role of anterior cingulate cortex (ACC) in attention is a matter of debate. One hypothesis suggests that its role is to monitor response-level conflict, but explicit evidence is somewhat lacking. In this study, the activation of ACC was compared in (a) color and number standard Stroop tasks in which response preparation and interference shared modality (response-level conflict) and (b) color and number matching Stroop tasks in which response preparation and interference did not share modality (non-response-level conflict). In the congruent conditions, there was no effect of task type. In the interference conditions, anterior cingulate activity in the matching tasks was less than that in the standard tasks. These results support the hypothesis that ACC specifically mediates generalized modality-independent selection processes invoked by response competition.

Testing Turing's five minutes, parallel-paired imitation game

Purpose – The purpose of this paper is to consider Turing's two tests for machine intelligence: the parallel-paired, three-participants game presented in his 1950 paper, and the “jury-service” one-to-one measure described two years later in a radio broadcast. Both versions were instantiated in practical Turing tests during the 18th Loebner Prize for artificial intelligence hosted at the University of Reading, UK, in October 2008. This involved jury-service tests in the preliminary phase and parallel-paired in the final phase. Design/methodology/approach – Almost 100 test results from the final have been evaluated and this paper reports some intriguing nuances which arose as a result of the unique contest. Findings – In the 2008 competition, Turing's 30 per cent pass rate is not achieved by any machine in the parallel-paired tests but Turing's modified prediction: “at least in a hundred years time” is remembered. Originality/value – The paper presents actual responses from “modern Elizas” to human interrogators during contest dialogues that show considerable improvement in artificial conversational entities (ACE). Unlike their ancestor – Weizenbaum's natural language understanding system – ACE are now able to recall, share information and disclose personal interests.