Context-Aware Adaptive Opportunistic Routing in Mobile Ad-hoc and Sensor Networks

Mobile ad-hoc networks (MANETs) and wireless sensor networks (WSNs) have been attracting increasing attention for decades due to their broad civilian and military applications. Basically, a MANET or WSN is a network of nodes connected by wireless communication links. Due to the limited transmission range of the radio, many pairs of nodes in MANETs or WSNs may not be able to communicate directly, hence they need other intermediate nodes to forward packets for them. Routing in such types of networks is an important issue and it poses great challenges due to the dynamic nature of MANETs or WSNs. On the one hand, the open-air nature of wireless environments brings many difficulties when an efficient routing solution is required. The wireless channel is unreliable due to fading and interferences, which makes it impossible to maintain a quality path from a source node to a destination node. Additionally, node mobility aggravates network dynamics, which causes frequent topology changes and brings significant overheads for maintaining and recalculating paths. Furthermore, mobile devices and sensors are usually constrained by battery capacity, computing and communication resources, which impose limitations on the functionalities of routing protocols. On the other hand, the wireless medium possesses inherent unique characteristics, which can be exploited to enhance transmission reliability and routing performance. Opportunistic routing (OR) is one promising technique that takes advantage of the spatial diversity and broadcast nature of the wireless medium to improve packet forwarding reliability in multihop wireless communication. OR combats the unreliable wireless links by involving multiple neighboring nodes (forwarding candidates) to choose packet forwarders. In opportunistic routing, a source node does not require an end-to-end path to transmit packets. The packet forwarding decision is made hop-by-hop in a fully distributed fashion. Motivated by the deficiencies of existing opportunistic routing protocols in dynamic environments such as mobile ad-hoc networks or wireless sensor networks, this thesis proposes a novel context-aware adaptive opportunistic routing scheme. Our proposal selects packet forwarders by simultaneously exploiting multiple types of cross-layer context information of nodes and environments. Our approach significantly outperforms other routing protocols that rely solely on a single metric. The adaptivity feature of our proposal enables network nodes to adjust their behaviors at run-time according to network conditions. To accommodate the strict energy constraints in WSNs, this thesis integrates adaptive duty-cycling mechanism to opportunistic routing for wireless sensor nodes. Our approach dynamically adjusts the sleeping intervals of sensor nodes according to the monitored traffic load and the estimated energy consumption rate. Through the integration of duty cycling of sensor nodes and opportunistic routing, our protocol is able to provide a satisfactory balance between good routing performance and energy efficiency for WSNs.

What Makes a Family Firm Innovative? CEO Risk-Taking Propensity and the Organizational Context of Family Firms

Investigating the new product portfolio innovativeness of family firms connects two important topics that have recently received considerable attention in innovation and family firm research. First, new product portfolio innovativeness has been identified as a critical determinant of firm performance. Second, research on family firms has focused on the questions of if and why family firms are more or less innovative than other organizational forms. Research investigating the innovativeness of family firms has often applied a risk-oriented perspective by identifying socioemotional wealth (SEW) as the main reference that determines firm behavior. Thus, prior research has mainly focused on the organizational context to predict innovation-related family firm behavior and neglected the impact of preferences and the behavior of the chief executive officer (CEO), which have both been shown to affect firm outcomes. Hence, this study aims to extend the previous research by introducing the CEO's disposition to organizational context variables to explain the new product portfolio innovativeness of small and medium-sized family firms. Specifically, this study explores how the organizational context (i.e., ownership by top management team [TMT] family members and generation in charge of the family firm) of family firms interacts with CEO risk-taking propensity to affect new product portfolio innovativeness. Using a sample of 114 German CEOs of small and medium-sized family firms operating in manufacturing industries, the results show that CEO risk-taking propensity has a positive effect on new product portfolio innovativeness. Moreover, the analyses show that the organizational context of family firms impacts the relationship between CEO risk-taking propensity and new product portfolio innovativeness. Specifically, the relationship between CEO risk-taking propensity and new product portfolio innovativeness is weaker if levels of ownership by TMT family members are high (high SEW). Additionally, the effect of CEO risk-taking propensity on new product portfolio innovativeness is stronger in family firms at earlier generational stages (high SEW). This result suggests that if SEW is a strong reference, family firm-specific characteristics can affect individual dispositions and, in turn, the behaviors of executives. Therefore, this study helps extend the knowledge on the determinants of new product portfolio innovativeness of family firms by considering an individual CEO preference and the organizational context variables of family firms simultaneously.

Innovations in Small and Medium-Sized Family Firms

Small and medium-sized firms are a prevalent organizational form in Germany. Their importance for the German economy is indisputable. Most of them are global market leaders in their niches and are considered to be a force for innovation in the German economy. The ability to be innovative in niche markets has been identified as the antecedent of their strong, or even dominant, competitive positions in their industries. The driver of this innovation success may well be the family, which distinguishes family firms from non-family firms. Nils Kraiczy analyzes if a family influences innovation in a family firm and if this influence has only positive effects. The dissertation focuses on the impact of top management teams on innovations interacting with family firm-specific characteristics. The author shows the complexity of family influence by presenting different effects of each investigated family firm-specific characteristic on the relationship between top management team behavior and innovation.

Characterisation and mitigation of beam-induced backgrounds observed in the ATLAS detector during the 2011 proton-proton run

This paper presents a summary of beam-induced backgrounds observed in the ATLAS detector and discusses methods to tag and remove background contaminated events in data. Trigger-rate based monitoring of beam-related backgrounds is presented. The correlations of backgrounds with machine conditions, such as residual pressure in the beam-pipe, are discussed. Results from dedicated beam-background simulations are shown, and their qualitative agreement with data is evaluated. Data taken during the passage of unpaired, i.e. non-colliding, proton bunches is used to obtain background-enriched data samples. These are used to identify characteristic features of beam-induced backgrounds, which then are exploited to develop dedicated background tagging tools. These tools, based on observables in the Pixel detector, the muon spectrometer and the calorimeters, are described in detail and their efficiencies are evaluated. Finally an example of an application of these techniques to a monojet analysis is given, which demonstrates the importance of such event cleaning techniques for some new physics searches.

Electron and photon energy calibration with the ATLAS detector using LHC Run 1 data

This paper presents the electron and photon energy calibration achieved with the ATLAS detector using about 25 fb−1 of LHC proton–proton collision data taken at centre-of-mass energies of √s = 7 and 8 TeV. The reconstruction of electron and photon energies is optimised using multivariate algorithms. The response of the calorimeter layers is equalised in data and simulation, and the longitudinal profile of the electromagnetic showers is exploited to estimate the passive material in front of the calorimeter and reoptimise the detector simulation. After all corrections, the Z resonance is used to set the absolute energy scale. For electrons from Z decays, the achieved calibration is typically accurate to 0.05% in most of the detector acceptance, rising to 0.2% in regions with large amounts of passive material. The remaining inaccuracy is less than 0.2–1% for electrons with a transverse energy of 10 GeV, and is on average 0.3% for photons. The detector resolution is determined with a relative inaccuracy of less than 10% for electrons and photons up to 60 GeV transverse energy, rising to 40% for transverse energies above 500 GeV.

Ready for a crisis? How supervisory boards affect the formalized crisis procedures of small and medium-sized family firms in Germany

Overcoming a crisis situation in which the socioemotional wealth (SEW) of a family is at risk can be threatened by a lack of formal crisis procedures, which can increase the probability of organizational decline. Thus, not being prepared for a crisis situation may be a critical factor in the long-term survival of family firms. From a corporate governance perspective, supervisory boards may achieve higher levels of crisis readiness. Applying the resourced-based view and SEW theory, we analyze the relationship between family ownership and formalized crisis procedures in 150 small and medium-sized German firms. Our results show that formalized crisis procedures decrease as family ownership increases. Including supervisory boards in our analysis, we find a significant moderating effect of supervisory boards on the relationship between family ownership and formalized crisis procedures. Specifically, our results suggest that family firms with supervisory boards show similar levels of formalized crisis procedures as non-family firms with supervisory boards. In contrast, family firms without supervisory boards exhibit lower levels of formalized crisis procedures compared with non-family firms without supervisory boards. We also discuss managerial implications, limitations, and future research.

Taking Root in the Silicon Forest: High-technology Firms as Surrogate Universities in Portland, Oregon

Most case studies of successful high-technology industry regions highlight the role of research universities in fostering regional economic development. The Portland, Oregon, region managed to root a thriving high-tech industry in the absence of this critical factor. In this article, I present a case study of the evolution of Portland's high-tech industry and propose that high-tech firms can act as surrogate universities that attract and develop labor, create knowledge, and function as incubators for startups. I conclude that planners working to develop high-tech industries in regions without major research universities should attract R&D-intensive firms, maintain information on key busineses and entrepreneurial ventures, support an innovation milieu, and set realistic goals.

Segmentation and Segregation Patterns of Women-Owned High-Tech Firms in Four Metropolitan Regions in the United States

Mayer H. Segmentation and segregation patterns of women-owned high-tech firms in four metropolitan regions in the United States, Regional Studies. The number of women starting and owning a business has increased dramatically and female entrepreneurs are entering non-traditional sectors such as high technology, construction and manufacturing. This paper investigates the trends in high-tech entrepreneurship by women in four US metropolitan regions (Silicon Valley, California; Boston, Massachusetts; Washington, DC; and Portland, Oregon). The research examines the sectoral and spatial segmentation patterns of women-owned high-tech firms. Although women are entering non-traditional sectors, the research finds that women entrepreneurs tend to own businesses in female-typed high-tech sectors. In established high-tech regions like Silicon Valley and Boston, male-typed and female-typed women-owned high-tech firms differ significantly in terms of sectoral and spatial segmentation regardless of firm age. While differences between male-typed and female-typed firms are not significant at the regional level for Washington, DC, the analysis shows significant intra-metropolitan differences for the female-typed high-tech firms. The paper concludes that sectoral and spatial segmentation are powerful dynamics that shape business ownership by women in high technology.

How Firms Make Friends: Communities in Private-Collective Innovation

When firms contribute to open source projects, they in fact invest into public goods which may be used by everyone, even by their competitors. This seemingly paradoxical behavior can be explained by the model of private-collective innovation where private investors participate in collective action. Previous literature has shown that companies benefit through the production process providing them with unique incentives such as learning and reputation effects. By contributing to open source projects firms are able to build a network of external individuals and organizations participating in the creation and development of the software. As will be shown in this doctoral dissertation firm-sponsored communities involve the formation of interorganizational relationships which eventually may lead to a source of sustained competitive advantage. However, managing a largely independent open source community is a challenging balancing act between exertion of control to appropriate value creation, and openness in order to gain and preserve credibility and motivate external contributions. Therefore, this dissertation consisting of an introductory chapter and three separate research papers analyzes characteristics of firm-driven open source communities, finds reasons why and mechanisms by which companies facilitate the creation of such networks, and shows how firms can benefit most from their communities.

Hit-and-run trophallaxis of small hive beetles

Some parasites of social insects are able to exploit the exchange of food between nestmates via trophallaxis, because they are chemically disguised as nestmates. However, a few parasites succeed in trophallactic solicitation although they are attacked by workers. The underlying mechanisms are not well understood. The small hive beetle (=SHB), Aethina tumida, is such a parasite of honey bee, Apis mellifera, colonies and is able to induce trophallaxis. Here, we investigate whether SHB trophallactic solicitation is innate and affected by sex and experience. We quantified characteristics of the trophallactic solicitation in SHBs from laboratory-reared individuals that were either bee-naïve or had 5 days experience. The data clearly show that SHB trophallactic solicitation is innate and further suggest that it can be influenced by both experience and sex. Inexperienced SHB males begged more often than any of the other groups had longer breaks than their experienced counterparts and a longer soliciting duration than both experienced SHB males and females, suggesting that they start rather slowly and gain more from experience. Successful experienced females and males were not significantly different from each other in relation to successful trophallactic interactions, but had a significantly shorter soliciting duration compared to all other groups, except successful inexperienced females. Trophallactic solicitation success, feeding duration and begging duration were not significantly affected by either SHB sex or experience, supporting the notion that these behaviors are important for survival in host colonies. Overall, success seems to be governed by quality rather than quantity of interactions, thereby probably limiting both SHB energy investment and chance of injury (<1%). Trophallactic solicitation by SHBs is a singular example for an alternative strategy to exploit insect societies without requiring chemical disguise. Hit-and-run trophallaxis is an attractive test system to get an insight into trophallaxis in the social insects.