Alternative Types of Ambiguity and their Effects on Climate Change Regulation.

This paper focuses on different types of ambiguity that affect climate change regulation. In particular, we analyze the effects of the interaction among three types of agents, namely, the decision-maker (DM), the climate change experts, and the society, on the probabilistic properties of green-house gas (GHG) emissions and the formation of environmental policy. These effects are analyzed under two types of ambiguity: "deferential ambiguity" and "preferential ambiguity". Deferential ambiguity refers to the uncertainty that the experts face concerning whose forecast (scenario) the DM will defer to. Preferential ambiguity stems from the potential inability of the DM to correctly discern the society's preferences about the desired change of GHG emissions. This paper shows that the existence of deferential and preferential ambiguities have significant effects on GHG emissions regulation.

Ambiguity aversion, modern Bayesianism and small worlds.

The central question of this paper is whether a rational agent under uncertainty can exhibit ambiguity aversion (AA). The answer to this question depends on the way the agent forms her probabilistic beliefs: classical Bayesianism (CB) vs modern Bayesianism (MB). We revisit Schmeidler's coin-based example and show that a rational MB agent operating in the context of a "small world", cannot exhibit AA. Hence we argue that the motivation of AA based on Schmeidler's coin-based and Ellsberg's classic urn-based examples, is poor, since they correspond to cases of "small worlds". We also argue that MB, not only avoids AA, but also proves to be normatively superior to CB because an MB agent (i) avoids logical inconsistencies akin to the relation between her subjective probability and objective chance, (ii) resolves the problem of "old evidence" and (iii) allows psychological detachment from actual evidence, hence avoiding the problem of "cognitive dissonance". As far as AA is concerned, we claim that it may be thought of as a (potential) property of large worlds, because in such worlds MB is likely to be infeasible.

Influence of lightness difference of single anterior tooth to smile attractiveness.

OBJECTIVES: To evaluate the influence of lightness difference of a single anterior maxillary tooth on difference smile attractiveness. METHODS: A frontal view full-portrait image of a smiling male Caucasian, was digitally modified altering a single tooth, creating a series of images with varying lightness (ΔL) for the maxillary central, lateral and canine. A total of 160 participants (80 dentists, 80 laypersons) were asked to fill out a Visual Analog Scale questionnaire for every image recording smile attractiveness. RESULTS: For central incisors ΔL≥1 negatively affected attractiveness. There was a higher tolerance for lightness mismatch when one lateral incisor is lighter and the same applies when the canine was darker. Difference in lightness affected smile attractiveness both for dentists and laypersons. No difference between males and females was observed for the dentists. For laypersons, females perceived smiles with lightness difference as significantly less attractive compared to males. Dentist's age did not affect smile attractiveness perception. Younger laypersons perceived darker color, as less attractive. CONCLUSIONS: Changes in lightness of a single anterior tooth significantly affected smile attractiveness in a different way for the central vs lateral vs canine. For the dentists, age and gender did not significantly affect smile perception, in contrast to laypeople. CLINICAL SIGNIFICANCE: Lightness differences of a single anterior tooth affects smile attractiveness.

Do agents' characteristics affect their valuation of 'common pool' resources? A full-preference ranking analysis for the value of sustainable river basin management.

In this paper we develop a full-preference ranking Choice Experiment (CE) designed to investigate how respondents evaluate a set of proposed improvements towards sustainable river basin management, as per the prescriptions of the European Union-Water Framework Directive (2000). The CE is applied in the Asopos River Basin (ARB) in Greece. Our interest is to test whether residency in the river basin, or otherwise, affects the preferences of the relevant agents. We first estimate a rank-ordered logistic regression based on a full set of choices in order to calculate the willingness to pay (WTP) of respondents for each one of the three attributes considered in the CE (i.e., environmental conditions, impact on the local economy and changes in the potential uses of water). The model is initially estimated for the full sample and then re-estimated twice for two sub-samples: the first one only includes the residents of Athens and the second only includes the residents of Asopos. Afterwards, we examine the effect of various demographic and socio-economic factors (such as income, gender, age, employment and education) on the estimates of our model in order to reveal any differences among respondents with different characteristics, mainly focusing on whether they reside or have personal experience of the RB under valuation. Thus, our analysis simultaneously provides a robustness check on previous findings in the literature and additional information about how various demographic and socio-economic characteristics affect the evaluation of the selected attributes.

Characterisation and management of ash produced in the hospital waste incinerator of Athens, Greece.

Bottom and fly ash samples (BASH and FASH) from the APOTEFROTIRAS S.A. medical waste incinerator (Athens, Greece) were investigated. Powder-XRD data and geochemical diagrams showed BASH to be an amorphous material, analogous to basaltic glass, and FASH consisting of crystalline compounds (mainly CaClOH). Bulk analyses by ICP-MS and point analyses by SEM-EDS indicated a high content of heavy metals, such as Fe, Cu and Cr, in both samples. However, BASH was highly enriched in Ni while FASH was additionally enriched in Zn and Pb. Gamma-ray measurements showed that the radioactivity of both ash samples, due to natural and artificial radionuclides ((137)Cs, (57)Co), was within the permissible levels recommended by IAEA. According to EN-type leaching tests, BASH was practically inert with regard to the mobility of the hazardous elements in aqueous media. FASH, however, showed a relatively high EN (and TCLP) leachability with regard to Pb and Zn. Finally, the stabilisation method, suggested for the treatment of FASH, included compression of the powder into briquettes using an appropriate machine and embedding the briquettes into pozzolanic cement blocks. After this treatment, TCLP and EN-type tests showed minimal release of Pb and Zn, thereby demonstrating a reliable management of ash waste.