Bayesian estimation of willingness-to-pay where respondents mis-report their preferences

We introduce a modified conditional logit model that takes account of uncertainty associated with mis-reporting in revealed preference experiments estimating willingness-to-pay (WTP). Like Hausman et al. [Journal of Econometrics (1988) Vol. 87, pp. 239-269], our model captures the extent and direction of uncertainty by respondents. Using a Bayesian methodology, we apply our model to a choice modelling (CM) data set examining UK consumer preferences for non-pesticide food. We compare the results of our model with the Hausman model. WTP estimates are produced for different groups of consumers and we find that modified estimates of WTP, that take account of mis-reporting, are substantially revised downwards. We find a significant proportion of respondents mis-reporting in favour of the non-pesticide option. Finally, with this data set, Bayes factors suggest that our model is preferred to the Hausman model.

Rapid radiation in spiny lobsters (Palinurus spp) as revealed by classic and ABC methods using mtDNA and microsatellite data

Background: Molecular tools may help to uncover closely related and still diverging species from a wide variety of taxa and provide insight into the mechanisms, pace and geography of marine speciation. There is a certain controversy on the phylogeography and speciation modes of species-groups with an Eastern Atlantic-Western Indian Ocean distribution, with previous studies suggesting that older events (Miocene) and/or more recent (Pleistocene) oceanographic processes could have influenced the phylogeny of marine taxa. The spiny lobster genus Palinurus allows for testing among speciation hypotheses, since it has a particular distribution with two groups of three species each in the Northeastern Atlantic (P. elephas, P. mauritanicus and P. charlestoni) and Southeastern Atlantic and Southwestern Indian Oceans (P. gilchristi, P. delagoae and P. barbarae). In the present study, we obtain a more complete understanding of the phylogenetic relationships among these species through a combined dataset with both nuclear and mitochondrial markers, by testing alternative hypotheses on both the mutation rate and tree topology under the recently developed approximate Bayesian computation (ABC) methods. Results: Our analyses support a North-to-South speciation pattern in Palinurus with all the South-African species forming a monophyletic clade nested within the Northern Hemisphere species. Coalescent-based ABC methods allowed us to reject the previously proposed hypothesis of a Middle Miocene speciation event related with the closure of the Tethyan Seaway. Instead, divergence times obtained for Palinurus species using the combined mtDNA-microsatellite dataset and standard mutation rates for mtDNA agree with known glaciation-related processes occurring during the last 2 my. Conclusion: The Palinurus speciation pattern is a typical example of a series of rapid speciation events occurring within a group, with very short branches separating different species. Our results support the hypothesis that recent climate change-related oceanographic processes have influenced the phylogeny of marine taxa, with most Palinurus species originating during the last two million years. The present study highlights the value of new coalescent-based statistical methods such as ABC for testing different speciation hypotheses using molecular data.

The biocontrol fungus Pochonia chlamydosporia shows nematode host preference at the infraspecific level

A RAPD-PCR assay was developed and used to test For competitive variability in growth of the nematode biological control fungus Pochonia chlamydosporia. Saprophytic competence in soil with or without tomato plants was examined in three isolates of the fungus: RES 280 (J), originally isolated from potato cyst nematode (PCN) cysts; RES 200 (1) and RES 279 (S), both originally isolated from root knot nematode (RKN) eggs. Viable counts taken at 70 d indicated that I was the best saprophyte followed by S, with J the poorest. RAPD-PCR analysis of colonies from mixed treatments revealed that there was a cumulative effect of adding isolates to the system. This Suggested that the isolates did not interact and that they may occupy separate niches in soil and the rhizosphere. To investigate parasitic ability, soils were seeded with two isolates of the fungus: J and S, singly or in combination. Tomato or potato plants were grown in these soils; free of nematodes, or inoculated with PCN or RKN, and incubated for 77 d. The abundance of the PCN isolate J in PCN cysts was significantly greater than that of the RKN isolate S but in RKN egg masses, S was significantly more abundant than J. RAPD-PCR analysis of colonies from mixed treatments confirmed that J was more abundant than S ill PCN cysts whereas the converse was observed on RKN egg masses. This substantiates the phenomenon of nematode host preference at the infraspecific level of P. chlamydosporia and highlights its relevance for biological control of plant parasitic nematodes.

The biocontrol fungus pochonia chlamydosporia shows nematode host preference at the infraspecific level

A RAPD-PCR assay was developed and used to test For competitive variability in growth of the nematode biological control fungus Pochonia chlamydosporia. Saprophytic competence in soil with or without tomato plants was examined in three isolates of the fungus: RES 280 (J), originally isolated from potato cyst nematode (PCN) cysts; RES 200 (1) and RES 279 (S), both originally isolated from root knot nematode (RKN) eggs. Viable counts taken at 70 d indicated that I was the best saprophyte followed by S, with J the poorest. RAPD-PCR analysis of colonies from mixed treatments revealed that there was a cumulative effect of adding isolates to the system. This Suggested that the isolates did not interact and that they may occupy separate niches in soil and the rhizosphere. To investigate parasitic ability, soils were seeded with two isolates of the fungus: J and S, singly or in combination. Tomato or potato plants were grown in these soils; free of nematodes, or inoculated with PCN or RKN, and incubated for 77 d. The abundance of the PCN isolate J in PCN cysts was significantly greater than that of the RKN isolate S but in RKN egg masses, S was significantly more abundant than J. RAPD-PCR analysis of colonies from mixed treatments confirmed that J was more abundant than S ill PCN cysts whereas the converse was observed on RKN egg masses. This substantiates the phenomenon of nematode host preference at the infraspecific level of P. chlamydosporia and highlights its relevance for biological control of plant parasitic nematodes.

Quantitative and qualitative differences in morphological traits revealed between diploid Fragaria species

Background and Aims: The aims of this investigation were to highlight the qualitative and quantitative diversity apparent between nine diploid Fragaria species and produce interspecific populations segregating for a large number of morphological characters suitable for quantitative trait loci analysis. Methods: A qualitative comparison of eight described diploid Fragaria species was performed and measurements were taken of 23 morphological traits from 19 accessions including eight described species and one previously undescribed species. A principal components analysis was performed on 14 mathematically unrelated traits from these accessions, which partitioned the species accessions into distinct morphological groups. Interspecific crosses were performed with accessions of species that displayed significant quantitative divergence and, from these, populations that should segregate for a range of quantitative traits were raised. Key Results: Significant differences between species were observed for all 23 morphological traits quantified and three distinct groups of species accessions were observed after the principal components analysis. Interspecific crosses were performed between these groups, and F2 and backcross populations were raised that should segregate for a range of morphological characters. In addition, the study highlighted a number of distinctive morphological characters in many of the species studied. Conclusions: Diploid Fragaria species are morphologically diverse, yet remain highly interfertile, making the group an ideal model for the study of the genetic basis of phenotypic differences between species through map-based investigation using quantitative trait loci. The segregating interspecific populations raised will be ideal for such investigations and could also provide insights into the nature and extent of genome evolution within this group.

Protonation of phenylboronic acid: comparison of G3B3 and G2MP2 methods

G3B3 and G2MP2 calculations using Gaussian 03 have been carried out to investigate the protonation preferences for phenylboronic acid. All nine heavy atoms have been protonated in turn. With both methodologies, the two lowest protonation energies are obtained with the proton located either at the ipso carbon atom or at a hydroxyl oxygen atom. Within the G3B3 formalism, the lowest-energy configuration by 4.3 kcal . mol(-1) is found when the proton is located at the ipso carbon, rather than at the electronegative oxygen atom. In the resulting structure, the phenyl ring has lost a significant amount of aromaticity. By contrast, calculations with G2MP2 show that protonation at the hydroxyl oxygen atom is favored by 7.7 kcal . mol(-1). Calculations using the polarizable continuum model (PCM) solvent method also give preference to protonation at the oxygen atom when water is used as the solvent. The preference for protonation at the ipso carbon found by the more accurate G3B3 method is unexpected and its implications in Suzuki coupling are discussed. (C) 2006 Wiley Periodicals, Inc.

Carbohydrate preference, acid tolerance and bile tolerance in five strains of Bifidobacterium

Aims: To assess the suitability of bifidobacteria for inclusion in synbiotic products on the basis of carbohydrate preference, acid and bile tolerance. Methods and Results: Five strains of Bifidobacterium were analysed for their carbohydrate preference from 12 substrates. Maximum growth rates were used to compare substrate preferences. Galacto-oligosaccharides and isomalto-oligosaccharides were well utilized by all the test species. Most bacteria tested could also utilize at least one type of fructan molecule. To determine transit tolerance of potentially probiotic bifidobacteria, acid and bile resistance was tested. A wide range acid resistance was found. Bile tolerance also varied. Conclusions: GOS and IMO were generally well utilized by the tested species. Other substrates were used to different degrees by the different species. Most bifidobacteria are poorly resistant to strongly acidic conditions with the exception of Bifidobacterium lactis Bb12. Bile tolerances were widely variable and it was shown that caution should be exercised when using colorimetric methods to assess bile tolerance. Significance and Impact of Study: The study allows the comparison of the properties of bifidobacteria, allowing a cost effective screen for the best species for use in synbiotic products to allow better survival and efficacy.

Effects of drying methods and conditions on antimicrobial activity of edible chitosan films enriched with galangal extract

The aim of this work was to study the effects of drying methods and conditions (i.e., ambient drying, hot air drying at 40 degrees C, vacuum drying and low-pressure superheated steam drying within the temperature range of 70-90 degrees C at an absolute pressure of 10 kPa) as well as the concentration of galangal extract on the antimicrobial activity of edible chitosan films against Staphylococcus aureus. Galangal extract was added to the film forming solution as a natural antimicrobial agent in the concentration range of 0.3-0.9 g/100 g. Fourier transform infrared (FTIR) spectra and swelling of the films were also evaluated to investigate interaction between chitosan and the galangal extract. The antimicrobial activity of the films was evaluated by the disc diffusion and viable cell count method, while the morphology of bacteria treated with the antimicrobial films was observed via transmission electron microscopy (TEM). The antimicrobial activity, swelling and functional group interaction of the antimicrobial films were found to be affected by the drying methods and conditions as well as the concentration of the galangal extract. The electron microscopic observations revealed that cell wall and cell membrane of S. aureus treated by the antimicrobial films were significantly damaged. (C) 2009 Elsevier Ltd. All rights reserved.

Flesh colour dominates consumer preference for chicken

Existing research investigating interactions between visual and oral sensory cues has tended to use model food systems. In contrast, this study compared product quality assessments of corn-fed and wheat-fed chicken products among persons recruited in Northern Ireland. Three approaches have been adopted to investigate the effect of colour upon consumer choice of chicken: sensory assessment under normal lighting; focus group discussion; and sensory assessment under controlled lighting conditions. Initial consumer sensory assessment indicated that wheat-fed chicken was perceived to be tenderer and to have a more intense flavour than that which was corn-fed. Qualitative enquiry discerned that this was because consumers perceived the yellow colour of corn-fed chicken negatively. Yellow-coloured corn-fed chicken was therefore again compared with wheat-fed chicken in terms of flavour, texture and overall liking with the flesh colour disguised by means of controlled lighting. Quality ratings for corn-fed chicken were more positive when the yellow flesh colour was disguised, with corn-fed chicken judged to be tenderer than wheat-fed chicken and more flavoursome. This study illustrates the importance of using a combination of methods to gain insight into interactions between different sensory modalities in consumer quality judgements and adds to previous research on the importance of colour upon consumer choice of real foods. (c) 2005 Elsevier Ltd. All rights reserved.

Organisational semiotics methods to assess organisational readiness for internal use of social media

The paper presents organisational semiotics (OS) as an approach for identifying organisational readiness factors for internal use of social media within information intensive organisations (IIO). The paper examines OS methods, such as organisational morphology, containment analysis and collateral analysis to reveal factors of readiness within an organisation. These models also help to identify the essential patterns of activities needed for social media use within an organisation, which can provide a basis for future analysis. The findings confirmed many of the factors, previously identified in literature, while also revealing new factors using OS methods. The factors for organisational readiness for internal use of social media include resources, organisational climate, processes, motivational readiness, benefit and organisational control factors. Organisational control factors revealed are security/privacy, policies, communication procedures, accountability and fallback.

Connections between concepts revealed by the electronic structure of carbon monoxide

Different models for the electronic structure of carbon monoxide are suggested in influential textbooks. Therefore, this electronic structure offers an interesting subject in teaching because it can be used as an example to relate seemingly conflicting concepts. Understanding the connections between ostensibly different methods and between different concepts, related or conflicting, is important in academic studies. The related reactivities of CO, O2, and N-2 and the notations of molecular orbitals are topics of interest and are discussed in detail.

Preference and consumption of a taste enhanced meat meal by older hospital patients: a pilot study

BACKGROUND: Older hospital patients are considered to be at risk of malnutrition due to insufficient dietary intake. OBJECTIVE: To determine whether taste enhancement, using ingredients naturally high in umami compounds, increases preference and consumption of a meal by older hospital patients. METHODS: 31 patients (65–92 years) on elderly carewards in aUKNHS Trust hospital took part in a single-blinded preference and consumption study. They tasted two meats (control and enhanced, presented in balanced order) and stated their preference. At lunch, control and enhanced cottage pie and gravy were served concurrently; patients were asked to consume ad libitum and intake was measured. RESULTS: Taste enhanced meat was significantly preferred (P = 0.001). Although mean consumption was higher for the enhanced compared to control meal (137 g versus 119 g), with higher levels of energy (103 kcal versus 82 kcal) and protein (4.6 g versus 3.4 g) consumed; differences were not significant. CONCLUSIONS: Natural ingredients rich in umami taste compounds can successfully be used to increase preference of meat based meals by older hospital patients. Larger trials are needed to determine whether such increases in preference can significantly increase consumption.

Organic and conventional fertilizer effects on a tritrophic interaction: parasitism, performance and preference of Cotesia vestalis

Interest in sustainable farming methods that rely on alternatives to conventional synthetic fertilizers and pesticides is increasing. Sustainable farming methods often utilize natural populations of predatory and parasitic species to control populations of herbivores, which may be potential pest species. We investigated the effects of several types of fertilizer, including those typical of sustainable and conventional farming systems, on the interaction between a herbivore and parasitoid. The effects of fertilizer type on percentage parasitism, parasitoid performance, parasitoid attack behaviour and responses to plant volatiles were examined using a model Brassica system, consisting of Brassica oleracea var capitata, Plutella xylostella (Lepidoptera) larvae and Cotesia vestalis (parasitoid). Percentage parasitism was greatest for P. xylostella larvae feeding on plants that had received either a synthetic ammonium nitrate fertilizer or were unfertilized, in comparison to those receiving a composite fertilizer containing hoof and horn. Parasitism was intermediate on plants fertilized with an organically produced animal manure. Male parasitoid tibia length showed the same pattern as percentage parasitism, an indication that offspring performance was maximized on the treatments preferred by female parasitoids for oviposition. Percentage parasitism and parasitoid size were not correlated with foliar nitrogen concentration. The parasitoids did not discriminate between hosts feeding on plants in the four fertilizer treatments in parasitoid behaviour assays, but showed a preference for unfertilized plants in olfactometer experiments. The percentage parasitism and tibia length results provide support for the preference–performance hypothesis

Reduced face preference in infancy: a developmental precursor to callous-unemotional traits?

Background Children with callous-unemotional (CU) traits, a proposed precursor to adult psychopathy, are characterized by impaired emotion recognition, reduced responsiveness to others’ distress, and a lack of guilt or empathy. Reduced attention to faces, and more specifically to the eye region, has been proposed to underlie these difficulties, although this has never been tested longitudinally from infancy. Attention to faces occurs within the context of dyadic caregiver interactions, and early environment including parenting characteristics has been associated with CU traits. The present study tested whether infants’ preferential tracking of a face with direct gaze and levels of maternal sensitivity predict later CU traits. Methods Data were analyzed from a stratified random sample of 213 participants drawn from a population-based sample of 1233 first-time mothers. Infants’ preferential face tracking at 5 weeks and maternal sensitivity at 29 weeks were entered into a weighted linear regression as predictors of CU traits at 2.5 years. Results Controlling for a range of confounders (e.g., deprivation), lower preferential face tracking predicted higher CU traits (p = .001). Higher maternal sensitivity predicted lower CU traits in girls (p = .009), but not boys. No significant interaction between face tracking and maternal sensitivity was found. Conclusions This is the first study to show that attention to social features during infancy as well as early sensitive parenting predict the subsequent development of CU traits. Identifying such early atypicalities offers the potential for developing parent-mediated interventions in children at risk for developing CU traits.

Preference reversals for ambiguity aversion

This paper finds preference reversals in measurements of ambiguity aversion, even if psychological and informational circumstances are kept constant. The reversals are of a fundamentally different nature than the reversals found before because they cannot be explained by context-dependent weightings of attributes. We offer an explanation based on Sugden's random-reference theory, with different elicitation methods generating different random reference points. Then measurements of ambiguity aversion that use willingness to pay are confounded by loss aversion and hence overestimate ambiguity aversion.