54 research outputs found
Identification and bisection of temporal durations and tone frequencies: common models for temporal and nontemporal stimuli
No full textTwo experiments examined identification and bisection of tones varying in temporal duration (Experiment 1) or frequency (Experiment 2). Absolute identification of both durations and frequencies was influenced by prior stimuli and by stimulus distribution. Stimulus distribution influenced bisection for both stimulus types consistently, with more positively skewed distributions producing lower bisection points. The effect of distribution was greater when the ratio of the largest to smallest stimulus magnitude was greater. A simple mathematical model, temporal range frequency theory, was applied. It is concluded that (a) similar principles describe identification of temporal durations and other stimulus dimensions and (b) temporal bisection point shifts can be understood in terms of psychophysical principles independently developed in nontemporal domains, such as A. Parducci's (1965) range frequency theory
Decision by sampling
No full textWe present a theory of decision by sampling (DbS) in which, in contrast with traditional
models, there are no underlying psychoeconomic scales. Instead, we assume that an
attribute's subjective value is constructed from a series of binary, ordinal comparisons to a
sample of attribute values drawn from memory and is its rank within the sample. We assume
that the sample reflects both the immediate distribution of attribute values from the current
decision's context and also the background, real-world distribution of attribute values. DbS
accounts for concave utility functions; losses looming larger than gains; hyperbolic temporal
discounting; and the overestimation of small probabilities and the underestimation of large
probabilities
Waarde van e-participatie voor integrale dienstverlening
No full textHet doel van dit document is om de relaties tussen verschillende vormen van participatie en overheidsdienstverlening te verkennen om zo gericht keuzen te kunnen maken over de bijdrage van e-participatie aan geïntegreerde, persoonsgerichte dienstverlening. Achtereenvolgens wordt ingegaan op de volgende vragen: • Welke vormen van participatie in de overheidsdienstverlening kunnen we onderscheiden? • Welke bijdrage kan e-participatie theoretisch en praktisch leveren aan het versterken van de overheidsdienstverlening? • Welke normatieve vragen kan de vormgeving van de verschillende vormen van e-participatie oproepen? • Welke media kunnen worden gebruikt om de verbeteringen van de bijdrage van e-participatie aan de overheidsdienstverlening vorm te geven? Het document eindigt met een voorstel voor een onderzoeks- en ontwerptraject. Daarbij zijn vier vormen van participatie als kansrijk gedefinieerd: Coproduceren op overheidssites, Tips and tricks, Feedback en Coproduceren op burgersites. Al deze vormen worden allereerst ondersteund met eenvoudige technologieën (asynchroon, tekstueel) om vervolgens ook te zoeken naar synchrone en multimediale mogelijkhede
Is rice becoming an inferior good? Food demand in the Philippines
No full textWhat are the prospects for demand for the main foodstuffs, particularly rice, in the Philippines? Countries which have traditionally consumed rice as the basic staple such as Japan, the Republic of Korea, and Taiwan are eating more wheat and wheat products. There is also a shift towards increased consumption of meats, dairy products, vegetable oils, and fruits and vegetables. A recent study found rice to be an inferior good in Japan, Taiwan, Malaysia, Singapore, Thailand, and Nepal. In this paper, the demand for cereals in the Philippines is analyzed. Instead of assuming separability, an alternative specification of the linear Almost Ideal Demand System (LA/AIDS) which includes rice, wheat, maize, meat, fish, fruits and vegetables, other foods, and non-food commodities for the Philippines is estimated using time-series data from 1961 to 1988. The effects of urbanization and dynamic factors such as habit formation in consumption are also considered in the empirical analysis. Then using the estimated parameters, the demand and income elasticities are estimated over the sample period. The parameters are used to generate baseline projections of cereal demand to 2000. Some policy implications and concluding remarks are given in the final section.Environmental Economics&Policies,Economic Theory&Research,Crops&Crop Management Systems,Food&Beverage Industry,Agricultural Research
Partner selection in the mycorrhizal mutualism
No full textPartner selection in the mycorrhizal symbiosis is thought to be a key factor stabilising the mutualism. Both plant hosts and mycorrhizal fungi have been shown to preferentially allocate resources to higher quality partners. This can help maintain underground cooperation, although it is likely that different plant species vary in the spatial precision with which they can select partners. Partner selection in the mycorrhizal symbiosis is presumably context-dependent and can be mediated by factors like (relative) resource abundance and resource fluctuations, competition among mycorrhizas, arrival order and cultivation history. Such factors complicate our current understanding of the importance of partner selection and its effectiveness in stimulating mutualistic cooperation
Order of arrival structures arbuscular mycorrhizal colonization of plants
No full textPriority effects - the impact of a species' arrival on subsequent community development - have been shown to influence species composition in many organisms. Whether priority effects among arbuscular mycorrhizal fungi (AMF) structure fungal root communities is not well understood. Here, we investigated whether priority effects influence the success of two closely related AMF species (Rhizophagus irregularis and Glomus aggregatum), hypothesizing that a resident AMF suppresses invader success, this effect is time-dependent and a resident will experience reduced growth when invaded. We performed two glasshouse experiments using modified pots, which permitted direct inoculation of resident and invading AMF on the roots. We quantified intraradical AMF abundances using quantitative PCR and visual colonization percentages. We found that both fungi suppressed the invading species and that this effect was strongly dependent on the time lag between inoculations. In contrast to our expectations, neither resident AMF was negatively affected by invasion. We show that order of arrival can influence the abundance of AMF species colonizing a host. These priority effects can have important implications for AMF ecology and the use of fungal inocula in sustainable agriculture
La société de construction Heimat : de l’habitation du fonctionnaire au logement de l’employé
No full textThe Heimat was a building company, involved in public housing in Germany between 1925 and 1933. The author takes the example of this firm to study the evolution of social housing projects designed for German white-collar workers (Angestellte) , a professional category which witnessed considerable growth during this period and was anxious to dissociate itself from workers. Founded by the G.D.A. Union, the Heimat had a preferential policy of awarding dwellings, and concentrated on the construction of blocks of flats to rent, complete with private gardens, and situated for the most part in Berlin. Although it did not have its own full-time architect, the company commissioned half of its Berlin projects from Paul Mebes. Setting out from an individualistic system, invented for housing civil servants, this architect developed his own collective architecture of a more anonymous nature. Thus modern dwellings were designed and mass-produced for a social category which was merging into the middle classes.Mengin Christine. La société de construction Heimat : de l’habitation du fonctionnaire au logement de l’employé. In: Histoire de l'art, N°31, 1995. Architecture. pp. 69-76
Analysis of a deep transcriptome from the mantle tissue of Patella vulgata Linnaeus (Mollusca: Gastropoda: Patellidae) reveals candidate biomineralising genes.
No full textThe gastropod Patella vulgata is abundant on rocky shores in Northern Europe and a significant grazer of intertidal algae. Here we report the application of Illumina sequencing to develop a transcriptome from the adult mantle tissue of P. vulgata. We obtained 47,237,104 paired-end reads of 51 bp, trialled de novo assembly methods and settled on the additive multiple K method followed by redundancy removal as resulting in the most comprehensive assembly. This yielded 29,489 contigs of at least 500 bp in length. We then used three methods to search for candidate genes relevant to biomineralisation: searches via BLAST and Hidden Markov Models for homologues of biomineralising genes from other molluscs, searches for predicted proteins containing tandem repeats and searches for secreted proteins that lacked a transmembrane domain. From the results of these searches we selected 15 contigs for verification by RT-PCR, of which 14 were successfully amplified and cloned. These included homologues of Pif-177/BSMP, Perlustrin, SPARC, AP24, Follistatin-like and Carbonic anhydrase, as well as three containing extensive G-X-Y repeats as found in nacrein. We selected two for further verification by in situ hybridisation, demonstrating expression in the larval shell field. We conclude that de novo assembly of Illumina data offers a cheap and rapid route to a predicted transcriptome that can be used as a resource for further biological study
Evolutionary signals of symbiotic persistence in the legume–rhizobia mutualism
No full textUnderstanding the origins and evolutionary trajectories of symbiotic partnerships remains a major challenge. Why are some symbioses lost over evolutionary time whereas others become crucial for survival? Here, we use a quantitative trait reconstruction method to characterize different evolutionary stages in the ancient symbiosis between legumes (Fabaceae) and nitrogen-fixing bacteria, asking how labile is symbiosis across different host clades. We find that more than half of the 1,195 extant nodulating legumes analyzed have a high likelihood (>95%) of being in a state of high symbiotic persistence, meaning that they show a continued capacity to form the symbiosis over evolutionary time, even though the partnership has remained facultative and is not obligate. To explore patterns associated with the likelihood of loss and retention of the N2-fixing symbiosis, we tested for correlations between symbiotic persistence and legume distribution, climate, soil and trait data. We found a strong latitudinal effect and demonstrated that low mean annual temperatures are associated with high symbiotic persistence in legumes. Although no significant correlations between soil variables and symbiotic persistence were found, nitrogen and phosphorus leaf contents were positively correlated with legumes in a state of high symbiotic persistence. This pattern suggests that highly demanding nutrient lifestyles are associated with more stable partnerships, potentially because they "lock" the hosts into symbiotic dependency. Quantitative reconstruction methods are emerging as a powerful comparative tool to study broad patterns of symbiont loss and retention across diverse partnerships
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