The Tourism Area Life Cycle Hypothesis: a Micro-Foundation

We provide a simple micro-foundation of the tourism area life cycle hypothesis, based on tourists’ utility maximization. As a result of social interactions among tourists which determine destinations popularity, the market share of visitors which decides to visit a specific destination follows a logistic dynamics, consistent with what predicted by the tourism area life cycle hypothesis. We show that different preference drivers explain the duration of the different tourism area life cycle stages: the net benefit from visiting the destination characterizes the exploration, involvement, and development phases, while social effects associated with destination popularity characterize the phases of consolidation and stagnation Different from previous studies our results hold true independently of whether we focus on the repeating or non-repeating segment of the tourism market. We also provide a calibration of our model to the case of the city of Venice (Italy) showing that it performs well in capturing the evolution of tourism in the historical center of the city over the last 60 years, suggesting that TALC-like dynamics may occur even in the context of cultural and heritage destinations

Effects of nitrogen on benthic diatom assemblages in high-elevation Central and Eastern Alpine lakes.

We explored patterns of benthic-diatom composition across 62 high-elevation Alpine lakes spanning a wide range of nitrogen (N) concentrations due to atmospheric deposition and background variation in lake and watershed characteristics (e.g., land cover, bedrock geology, lake depth, and elevation). Our goals were to (i) assess the effect of lake-water N concentration on benthic-diatom composition during late summer or fall conditions and (ii) identify policy- relevant response thresholds. The analyses were carried out on an existing data set of diatom and water-chemistry data (EMERGE set), integrated with new data. Multivariate and correlation analyses revealed associations between pH, N concentration, and benthic-diatom composition, but the effects of pH and N were confounded. However, partial correlation analysis allowed us to identify ‘N-responsive diatoms’, i.e., diatom taxa with non-spurious association with N. Focusing on these taxa, we detected a decline in the abundance of taxa preferring low N concentrations and an increase in the abundance of taxa preferring high N concentrations starting at NO 3 concentrations of approximately 5 μmol L -1 . We interpreted this shift as an effect of watershed N saturation due to atmospheric N deposition. Based on the results, we suggest a concentration threshold of 5 μmol NO 3 L -1 during late-summer or fall to prevent change in benthic diatoms in high-elevation Alpine lakes affected by N deposition

Meiofaunal ecology in harsh environments: refugia and stepping stones, a case study in a deglaciating Alpine area

Climate change and progressive glacier loss are leading to rapid ecological shifts in alpine aquatic systems. Rock glaciers and paraglacial features such as proglacial lakes, moraines, and taluses can alter the gradients of glacial influence along alpine river networks. Particularly relevant is the effect of rock glacial streams on invertebrates, although the hydrology and ecology of such high-elevation stream types is still scarcely known. We investigated the main meiofaunal component of benthic communities of different stream types in a deglaciating area of the Italian Alps, i.e., Crustacea Copepoda. We used an index of habitat mildness based on water temperature, channel stability, turbidity, and organic detritus, to measure the difference in community metrics over a gradient of habitat amelioration, driven by the mixing of distinct stream types (glacial, rock-glacial, snowmelt, mixed) and their interactions with paraglacial features. The composition of copepod communities of rock-glacial sites differed from the one of the other stream types, particularly it was very different from the kryal sites, and more similar to the rhithral and krenal ones. Under progressive deglaciation, rock glaciers and paraglacial features will increasingly influence the meiofaunal communities of alpine river networks. As they host a higher number of taxa and individuals than non-glacial locations, rock glacial streams may act as stepping stones facilitating colonization following glacier retreat. After glacier loss, rock glacial streams may represent climate refugia for cold adapted taxa and/or kryal specialists, because the slow thawing of their ice might sustain cold water conditions for a longer period of time

The Equity Premium Puzzle: An Application of an Agent-Based Evolutionary Model

We describe an agent-based model of a financial market with a stock and a bond. Agents compete in repeated rounds, decide whether to acquire costly information and can pick one of 16 strategies to allocate their investments, under evolutionary pressure driven by the comparison of the realized short-term revenues from trading. We show that, while in- formed traders survive in some cases, the equilibrium shares are strongly biased in favor of strategies that make little use of information and sys- tematically overestimate the riskiness of the stock. As a consequence, the majority of the population ends up in buying fewer stocks than would be otherwise expected or deemed rational. This evolutionary dynamics offers a novel way to explain the equity pre- mium puzzle first described by Mehra and Prescott (The equity pre- mium: A puzzle. Journal of Monetary Economics 1985), according to which it’s hard to find reasons for the widespread lack of investment in risky assets. Evolution based on a straightforward comparison of rev- enues is a simple and cognitively appealing avenue to reach a population of traders using (over-)cautious strategies to curb the risk of long-term “financial extinction”. Simulations run in NetLogo also demonstrate that very little information may be used in noisy markets or when the cost of information is substantial

Benthic diatom communities in two proglacial lakes with different glacial influence (Cevedale glacier, Italy).

Climatic changes induce cascadeeffects on high mountain headwaters. Due to the current deglaciation, proglacial lakes increased worldwide in number and volume in the last decades, thus becoming more represented ecosystems in high mountain landscapes. With the progression of glacier retreat, proglacial lakes rapidly evolve from ice contact conditions towards ice distal conditions. The final evolution stage is a clear water mountain lake, with no glacial influence. In the European Alps, ice distal proglacial lakes represent the largest proportion of high mountain lakes, in comparison with ice contact ones and clear lakes. Glacial runoff is typically cold and contains large amounts of inorganic suspended solids (so called “glacial flour”). Due to low water temperature and high turbidity, proglacial lakes are highly selective habitats, where planktonic communities are taxonomically simplified and quantitatively scarce. Nonetheless, littoral habitat conditions may sustain algal growth. However, benthic assemblages have been scarcely addressed by studies on Alpine proglacial lakes regarding qualitative and especially quantitative aspects. Here, we provide a first characterisation of the littoral diatom assemblages of two Alpine proglacial lakes with different glacial influence and discuss differences in community composition between the ice contact and the ice distal lake habitat. The two lakes are located between 2700 and 2900 m a.s.l. in the Martello Valley (Stelvio National Park, Province of Bolzano, Italy). They formed in the past decades in the depressions of the land surface shaped by the retreat of the Cevedale glacier and are both dammed by moraines. The ice contact lake (CL) receives glacial runoff flowing on debris-covered ice. The ice distal lake (DL) is about 500 m downstream and hydrologically connected to CL. In the ice-free seasons 2022 and 2023, we collected quantitative diatom samples from colonised substrata (stones or cohesive sediment) during the different stages of the Alpine glacial summer (snow melt, glacier ablation and base flow). In parallel, we collected water samples to analyse chemical habitat conditions and installed temperature dataloggers in the water column to calibrate a 2D laterally-averaged hydrodynamic model that allowed to reconstruct lake thermal dynamics. The two lacustrine habitats differed mainly in water turbidity, littoral water temperature and thermal dynamics, i.e., stratification patterns. In addition, we found differences in the benthic diatom communities of the two proglacial lakes. Alpha diversity was higher in the ice distal lake (DL), where we found species that were not observed in the ice contact lake (CL). In CL, diatom density peaks corresponded to the increase of Achnanthidium minutissimum s.l. (Kützing) Czarnecki, which was the numerically dominant species in all the samples in this lake. Density peaks in DL were characterised by different dominant species during the Alpine summer and the community composition showed a species succession. Furthermore, in DL, we observed a stable population of Pinnularia bullacostae Krammer & Lange-Bertalot. At the best of out knowledge, this is the first record of the species in the European Alp

Do dissolved heavy metals enter the food webs of alpine streams?

The Euregio - investigates the origin, export, and ecological effects of trace elements in river networks affected by rock glacier thawing and glacier retreat. Permafrost degradation and glacier recession can cause elevate export of solutes, including heavy metals, into river networks while the contribution from groundwater is often negligible. However, the ecological effects remain understudied. We assessed if and how trace element enrichment causes biomagnification processes in the aquatic organisms by characterizing the foodwebs of different stream types (intact and relict rock glaciers, and reference spring draining an area without periglacial landforms/glaciers/permafrost) with 13 15N isotopic ratios analysis and measuring the content of trace elements in each component of the foodweb. The investigation was conducted in 2022 in two catchments in South-Tyrol: Lazaun and Madritsch/Madriccio Valleys. The analysed matrices were: CPOM, FPOM, epilithic biofilms, bryophytes, and benthic invertebrates of different taxa characterized and grouped by feeding habit (omnivore, carnivore, herbivore, detritivore). The same trace elements were measured in the water of each stream type. As expected, most of the biomagnification occurred in streams originating from intact rock glaciers

Técnica de criação de Anastrepha fraterculus (Wied., 1830) (Diptera: Tephritidae) em laboratório utilizando hospedeiro natural.

Uma técnica para criação de todas as fases de desenvolvimento da mosca-das-frutas sul-americana, Anastrepha fraterculus (Wied., 1830) (Diptera: Tephritidae), em laboratório (T 24 ± 2°C; UR 70 ± 10% e fotofase 16 horas) utilizando dieta natural foi avaliada e descrita. Os adultos foram criados em gaiolas plásticas de polietileno transparente (41 x 29,5 x 30 cm) e alimentados com dieta artificial contendo extrato de soja, açúcar mascavo e gérmen de trigo, nas proporções de 3:1:1, além de água. Em cada gaiola, foi utilizada uma densidade média de 167 ± 25 casais. As fêmeas ovipositaram em frutos de mamão-papaia (Carica papaya L.) trocados a intervalos de 48 horas e mantidos em caixas plásticas (37 x 14 x 29 cm) com fundo coberto por vermiculita. Sobre a camada de vermiculita, foi colocada uma tela plástica de malha de 2 mm, para facilitar a retirada dos restos de mamão desidratado após o desenvolvimento larval. As larvas completaram o desenvolvimento no mamão passando à fase de pupa após 15 ± 2 dias. Em cada mamão (401 ± 16 gramas), foram coletadas 168 ± 27 pupas, obtendo-se 385 ± 44 pupas (viabilidade de 95 ± 2%) por semana, com peso médio de 1,33 ± 0,05 gramas a cada 100 pupas. Os insetos obtidos podem ser destinados a condução de bioensaios ou na manutenção da criação. A metodologia descrita permite o desenvolvimento de uma geração (ovo-adulto) a cada 32 ± 2 dias, perfazendo aproximadamente 11 gerações/ano.bitstream/item/31529/1/bop015.pd

Rock glaciers and paraglacial features influence stream invertebrates in a deglaciating Alpine area

This is the pre-peer reviewed version of the following article: Brighenti, S, Tolotti, M, Bertoldi, W, Wharton, G, Bruno, MC. Rock glaciers and paraglacial features influence stream invertebrates in a deglaciating Alpine area. Freshwater Biology. 2020; 00: 1– 14. https://doi.org/10.1111/fwb.13658, which has been published in final form at https://doi.org/10.1111/fwb.13658. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions

Identity, reputation and social interaction with an application to sequential voting

We analyze binary choices in a random utility model assuming that the agent's preferences are affected by conformism (with respect to the behavior of the society) and coherence (with respect to his identity). We apply the analysis to sequential voting when voters like to win

Practical strategies for agent-based negotiation in complex environments

Agent-based negotiation, whereby the negotiation is automated by software programs, can be applied to many different negotiation situations, including negotiations between friends, businesses or countries. A key benefit of agent-based negotiation over human negotiation is that it can be used to negotiate effectively in complex negotiation environments, which consist of multiple negotiation issues, time constraints, and multiple unknown opponents. While automated negotiation has been an active area of research in the past twenty years, existing work has a number of limitations. Specifically, most of the existing literature has considered time constraints in terms of the number of rounds of negotiation that take place. In contrast, in this work we consider time constraints which are based on the amount of time that has elapsed. This requires a different approach, since the time spent computing the next action has an effect on the utility of the outcome, whereas the actual number of offers exchanged does not. In addition to these time constraints, in the complex negotiation environments which we consider, there are multiple negotiation issues, and we assume that the opponents’ preferences over these issues and the behaviour of those opponents are unknown. Finally, in our environment there can be concurrent negotiations between many participants. Against this background, in this thesis we present the design of a range of practical negotiation strategies, the most advanced of which uses Gaussian process regression to coordinate its concession against its various opponents, whilst considering the behaviour of those opponents and the time constraints. In more detail, the strategy uses observations of the offers made by each opponent to predict the future concession of that opponent. By considering the discounting factor, it predicts the future time which maximises the utility of the offers, and we then use this in setting our rate of concession. Furthermore, we evaluate the negotiation agents that we have developed, which use our strategies, and show that, particularly in the more challenging scenarios, our most advanced strategy outperforms other state-of-the-art agents from the Automated Negotiating Agent Competition, which provides an international benchmark for this work. In more detail, our results show that, in one-to-one negotiation, in the highly discounted scenarios, our agent reaches outcomes which, on average, are 2.3% higher than those of the next best agent. Furthermore, using empirical game theoretic analysis we show the robustness of our strategy in a variety of tournament settings. This analysis shows that, in the highly discounted scenarios, no agent can benefit by choosing a different strategy (taken from the top four strategies in that setting) than ours. Finally, in the many-to-many negotiations, we show how our strategy is particularly effective in highly competitive scenarios, where it outperforms the state-of-the-art many-to-many negotiation strategy by up to 45%.EThOS - Electronic Theses Online ServiceGBUnited Kingdo