A credit-based approach to scalable video transmission over a peer-to-peer social network

PhDThe objective of the research work presented in this thesis is to study scalable video transmission over peer-to-peer networks. In particular, we analyse how a credit-based approach and exploitation of social networking features can play a significant role in the design of such systems. Peer-to-peer systems are nowadays a valid alternative to the traditional client-server architecture for the distribution of multimedia content, as they transfer the workload from the service provider to the final user, with a subsequent reduction of management costs for the former. On the other hand, scalable video coding helps in dealing with network heterogeneity, since the content can be tailored to the characteristics or resources of the peers. First of all, we present a study that evaluates subjective video quality perceived by the final user under different transmission scenarios. We also propose a video chunk selection algorithm that maximises received video quality under different network conditions. Furthermore, challenges in building reliable peer-to-peer systems for multimedia streaming include optimisation of resource allocation and design mechanisms based on rewards and punishments that provide incentives for users to share their own resources. Our solution relies on a credit-based architecture, where peers do not interact with users that have proven to be malicious in the past. Finally, if peers are allowed to build a social network of trusted users, they can share the local information they have about the network and have a more complete understanding of the type of users they are interacting with. Therefore, in addition to a local credit, a social credit or social reputation is introduced. This thesis concludes with an overview of future developments of this research work

Could there be unintended effects of government support for seafood traceability implementation on business planning? Results of a survey among Italian fishery businesses

Governments have intervened in food, agricultural and fisheries markets through various support programs to promote adoption of traceability practices and systems in order to raise food safety levels and increase industry competitiveness. The aim of this paper is to investigate intended and unintended effects of participation in such supporting programs. Intended effects comprise of the impacts on traceability capacity levels, costs and benefits of program participants vs. comparable non-participants. Unintended effects concern the firms’ planning accuracy which we propose to measure through deviations of actual from expected outcomes. We conduct our empirical analysis based on a sample of 55 Italian fishery businesses which we divide in firms who received support, a comparable control group and the remaining sample. Although we find that recipients of government support have higher average levels of traceability capacity and overall benefits than the control group, differences are not statistically significant. In regards to the unintended effects of government support, we find that recipients of government support reported larger deviations of actual from expected benefits than the control group did. While these differences were not significant at the aggregate level, significant differences are found at the level of specific benefit categories. For example, support recipients had overestimated sales and price related benefits but severely underestimated efficiency gains in operations. The results suggest that the motivation for participating in a government support program may not align with the firm’s strategic goals. This misalignment may reduce planning accuracy

Evidence of slope instability in the Southwestern Adriatic Margin

International audienceThe Southwestern Adriatic Margin (SAM) shows evidence of widespread failure events that generated slide scars up to 10 km wide and extensive slide deposits with run out distances greater than 50 km. Chirp-sonar profiles, side-scan sonar mosaics, multibeam bathymetry and sediment cores document that the entire slope area underwent repeated failures along a stretch of 150 km and that mass-transport deposits, covering an area of 3320 km2, are highly variable ranging from blocky slides to turbidites, and lay on the lower slope and in the basin. The SAM slope between 300?700 m is impacted by southward bottom currents shaping sediment drifts (partly affected by failure) and areas of dominant erosion of the seafloor. When slide deposits occur in areas swept by bottom currents their fresh appearence and their location at seafloor may give the misleading impression of a very young age. Seismic-stratigraphic correlation of these deposits to the basin floor, however, allow a more reliable age estimate through sediment coring of the post-slide unit. Multiple buried failed masses overlap each other in the lower slope and below the basin floor; the most widespread of these mass-transport deposits occurred during the MIS 2-glacial interval on a combined area of 2670 km2. Displacements affecting Holocene deposits suggest recent failure events during or after the last phases of the last post-glacial eustatic rise. Differences in sediment accumulation rates at the base or within the sediment drifts and presence of downlap surfaces along the slope and further in the basin may provide one or multiple potential weak layers above which widespread collapses take place. Neotectonic activity and seismicity, together with the presence of a steep slope, represent additional elements conducive to sediment instability and failure along the SAM. Evidence of large areas still prone to failure provides elements of tsunamogenic hazard

Comparison of different clustering methods for investigating, individual differences using choice experiments

Different strategies for investigating individual differences among consumers using choice experiments are compared. The paper is based on a consumer study of iced coffee in Norway. Consumers (n = 102) performed a choice task of twenty different iced coffee profiles varying in coffee type, production origin, calorie content and price following an orthogonal design. Consumer factors, such as socio-demographics, attitudes and habits, were also collected. Choice data will be analysed using two different clustering strategies. Strategy one is the most classical approach called Latent Class Logit (LCL) model, while Strategy two uses Mixed Logit (ML) model combined with Principal Component Analysis (PCA) for visual segmentation or with automatic clustering detection using Fuzzy C Means clustering (FCM). The clusters obtained can be interpreted using external consumer factors by using the Partial Least Square – Discrimination Analysis (PLS-DA) model. The different approaches are compared in terms of data analysis methodologies, modeling, outcomes, interpretation, flexibility, practical issues and user friendliness

Perceived Traceability Costs and Benefits in the Italian Fisheries Supply Chain

The paper proposes a model in which it is hypothesized that firm characteristics influence both costs and benefits of traceability. The proposed model differentiates between aggregate measures and specific categories, as well as between expected costs and benefits on the one hand and perceived actual outcomes on the other, and is tested in a series of regression analyses based on a survey sample of 60 Italian fish processors. The findings indicate that firm characteristics are not strongly associated with any specific cost or benefit measure. However, expected overall benefits are highly significantly impacted by firm size and the number of quality management systems certified, while actual overall benefits only by firm size. Finally, the study also finds considerable discrepancies between expected and actual costs and benefits. The managerial implications of the findings are discussed

Role of Sensory Attributes in the Food Marketing: An Exploratory Analysis in the Italian Organic Food Producers

 This paper explores in-depth sensory experiences, expectations and perceptions of organic producers regarding the role played by sensory properties in organic market, using a qualitative marketing research technique. Ten in-depth interviews supported by semi-structured questionnaire were performed in Italy during 2009. Findings shows that organic producers stated that sensory tests are mainly carried out empirically, they are not systematic and often performed by non trained assessors, even if they are completely aware of the importance of sensory information. Interviewees think that sensory attributes may play a primary or at least complementary role in consumer choice in order to adding-value and drivers for purchase motivations, but at the same time highlighted also the negative influence of variability in sensory features and the key role played by sensory education and training. Finally, organic producers expressed the need and the intention to plan scientific sensory tests with trained personnel in order to improve sensory properties of organic food although smallest companies declared difficulties since the high costs of sensory analysis

Investigating consumer food waste decisions: a cross-country comparison between Thailand and the United Kingdom

Food waste is increasingly recognized by policymakers worldwide to be an environmental, economic and food security priority where consumer decisions play a key role. Literature shows that there is uncertainty about consumer decisions to waste food which likely reflect trade-offs and economic incentives. Using the experimental vignette methodology, in an online stated survey, we investigated consumers’ food waste decisions in developed and developing countries. Specifically, we examined and compared consumers’ decisions to discard food in United Kingdom and Thailand during different eating scenarios which vary the presence/absence of other people during eating, place of eating, cost of the meal, amount of leftover food, and future meal plan. The results show that consumers both in the United Kingdom and Thailand are more likely to save food when eating at home, when the cost of a meal is high, and a full meal is left. Furthermore, while British consumers are more likely to save food when they have no meal plan for the following day, Thai consumers are more likely save food when eating alone. These findings have important implications and provide useful recommendations to policymakers and other stakeholders that aim to adopt FW reduction strategies

Impact of Firm Characteristics on Expected and Actual Traceability Costs and Benefits in the Italian Fishery Supply Chain

Since 2005, the implementation of a traceability system is mandatory to all European food chain operators. The balance of costs to build and maintain the traceability system and benefits of traceability depends on the firm’s traceability objectives and its resources, as reflected in characteristics, such as adopted quality management systems (QMS) or firm size. Mora and Menozzi (2005) mention that the cost of traceability is lower when firms already have a QMS in place. Moreover, US producers exporting to multiple destinations, in particular EU and Japan, need to comply with more stringent traceability regulations (De Souza Monteiro and Caswell 2004). This may request the adoption of more sophisticated and costly traceability systems. Food operators tend to have a good understanding of traceability cost, while performance benefits are usually more difficult to grasp (Verdenius 2006). This research aims at improving the understanding of how expected and actual costs and perceived benefits are influenced by firm characteristics (Meuwissen et al. 2003). This paper proposes a conceptual decision model that incorporates firm characteristics and both expected and actual costs and benefits of traceability. It is hypothesized that firm characteristics influence both expected and actual costs and benefits, while the level of traceability is influenced by expected and actual costs and perceived benefits as well as firms’ characteristics. Costs can be divided into implementation and operation/maintenance costs. Benefits can arise from compliance with regulatory requirements, enhanced recall performance, improved marketing performance and increased supply chain efficiency (Sparling and Sterling 2004).The analysis uses a sample of 60 Italian fish processing businesses that were surveyed in 2008. Indicators of firm’s characteristics such as number of QMS certifications, operations complexity, firm size and complexity of customer requirements, are entered as independent variables in regression analyses to predict expected and actual costs and perceived benefits which were measured on 9 point semantic scales and constant sum scales. The findings show that none of the firm characteristics investigated influence costs, while firm size and QMS certifications influence benefits in different ways. Somewhat surprisingly, firm size was found to be negatively correlated with expected and actual benefits; i.e. larger firms reported lower benefits both expected ex ante and realized ex post traceability system implementation. Finally, the number of QMS certifications is positively associated with expected benefits; i.e. expected benefits increase with the number of QMS certifications acquired by a firm, but no association with actual perceived benefits of traceability was found

Comparison of two different strategies for investigating individual differences among consumers in choice experiments. A case study based on preferences for iced coffee in Norway

Two different strategies for investigating individual differences among consumers in choice experiments using the Mixed Logit Model are compared. The study is based on a consumer study of iced coffees in Norway. Consumers (n=102) performed a choice task of twenty different iced coffee profiles varying in coffee type, production origin, calorie content and price following an orthogonal design. Consumer attributes, such as socio-demographics, attitudes and habits, were also collected. Choice data were first analyzed using the Mixed Logit Model and then two different approaches were adopted for investigating consumer attributes. The first strategy, called one-step strategy, includes the consumer attributes directly in the Mixed Logit Model. The second strategy, called multi-step strategy, combines different methods of analysis such as Mixed Logit Model based on the design factors only, followed by Principal Component Analysis and Partial Least Squares regression to study consumer attributes. The two approaches are compared in terms of data analysis methodologies, outcomes, practical issues, user friendliness, and interpretation. Overall, we think the multi-step strategy is the one to be preferred in most practical applications because of its flexibility and stronger exploratory capabilities

Consumers’ valuation for lab produced meat: an investigation of naming effects

“In-vitro” meat (IVM) technology could be seen as a solution that could overcome some of the concerns linked to conventional meat production, such as the expected demand increase, pressure on crop outputs, large greenhouse emission, high land, energy and water usage as well as consumers’ concerns related to animal welfare. One of the main drawback of IVM is that consumers’ might be reluctant to consume meat from this technology due to the perceived revulsion, lack of naturalness, taste, uncertainty about environmental benefits, and safety concerns. In this research, we aim to investigate consumers’ perception and willingness to pay (WTP) for IVM chicken by testing whether the use of different names for the IVM technology (i.e. “cultured”, “lab-grown” and “artificial”) will lead to different consumers’ preferences and WTP values. We conducted an online choice experiment (CE) in the United States with 625 participants to elicit consumers’ WTP for IVM fresh skinless boneless chicken breast products. To test naming effects, we used a between-subjects approach by randomly assigning respondents to three treatments. The treatments differed only on the name used to describe IVM technology (i.e. “cultured”, “lab-grown” and “artificial”). Results from Random Parameters Logit (RPL) models in WTP space shows that on average consumers prefer fresh skinless boneless chicken breast products produced with conventional meat technology with information about antibiotics free. Consumers tend to highly reject the IVM technology, with strong differences across the names. The term “cultured” is less disliked than the terms “artificial” and “lab-grown”. Finally, implications and suggestions for policy makers and food operators are discussed along with future research avenues