FIRST-PRINCIPLES INVESTIGATION OF THE ELECTRONIC AND TRANSPORT PROPERTIES OF CARBON ATOM WIRES

The last years have witnessed an ever increasing interest in the field of molecular electronics, in which molecules connected with two or more electrodes are used as main building blocks to fabricate the components of integrated circuits. The achievement of high performance interconnects is one of the key step for the realization of such devices. In this context, conjugated carbon wires are the most promising candidates to this role due to their structural stability and their experimental feasibility. In particular we investigated the transport properties of systems where a freestanding conjugated carbon chain is contacted with two electrodes in order achieve a two-terminal device. Although some important issues had already been investigated in this field when starting this project, information were very scattered and a well-rounded perspective of the key aspects affecting the electron transport was missing. This thesis represents one attempt to fill this gap first in the case of Ag-chain-Ag systems and then for graphene-chain-graphene devices. Specifically we focused on the role that the chain-electrode junction plays in determining the characteristics of such systems, finding that the contact geometry strongly affect the transport properties. In fact, for Ag-chain-Ag systems, qualitative different transport properties have been found depending on the adsorption site on the silver surface, while results showed only a weak dependence on the chain length. Moreover we observed that those results can be extended to "tip-like" contacts, mimicking a more realistic electrodic surface. As opposite, linking atoms such as sulfur or silicon strongly influence the conductance. We further demonstrated that the vibrational motion of the atoms has negligible effects on the transport properties for a very large range of temperature. Finally we also critically assessed the reliability of our results using the optical properties of the gas-phase molecules to benchmark the adopted setup. The results obtained for graphene-chain-graphene devices confirmed that the junction plays a central role in determining the strength of the electrode-chain coupling, and in turn, the conductance. We first analyzed in details the transport properties of single chains connected to ideal electrodes, investigating their geometrical and electronic structure in order to establish a connection with their transport properties. Furthermore, at odds with the above mentioned metal-C-metal systems, we found that "tip-like" junctions here have dramatic effects on the transport properties. More importantly, we investigated the possibility to observe quantum interference, chemical gating and conductance switching behaviors in such systems

The internal limits to firms' nonmarket activities

It is well documented that firms develop nonmarket strategies to try to shape public policy changes to their advantage. But are there no limits to this? This paper argues that there is in fact an important limitation, internal to the firm, which comes from the necessity for firms to integrate market and nonmarket activities. Because the two types of activities are not always complements but sometimes substitutes, firms end up giving up part of their nonmarket activities to avoid restricting the development of their market strategies. This argument is tested in the context of the European telecommunications industry. Results suggest that there is reasonable ground for optimism regarding the potentially negative influence that firms' nonmarket activities might play in a democracy

Migration routes of the Magnolia Marbler

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Private politics daily: What makes firms the target of internet/media criticism? An empirical investigation of firm, industry, and institutional factors

Private politics refers to situations in which activists or NGOs try to push firms to conform to social standards (regarding, for instance, human rights and environmental protection) without public policy intervention. The existing literature on private politics has focused on large campaigns such as consumer boycotts, and looked at the impact of those boycotts on firms' financial performance and on the likelihood that firms comply with activist demands. Even though these large campaigns are important, focusing on them leads to neglecting the fact that a large portion of the time and resources that activists consecrate to private politics is used to monitor firms and criticize them through Internet posting and media statements, rather than to launch high profile campaigns. Little is known, however, about what drives these activists when they criticize companies, why they target certain companies and not others, and whether this criticism should be considered as a primary step in the production of full-fledged campaigns. In this paper, we fill this gap by exploring a unique international database of CSR-based criticisms against Fortune 500 companies for the 2006-2009 period. This database allows us to look at the impact of a broad range of factors including industry differences, country/institutional differences and firm-specific dimensions, on the likelihood that a certain firm will be targeted by activist critique. Results indicate that criticism is driven by strategic intents. Similar to previous literature, large and visible firms in certain industries are more targeted than others. In addition, these firms also tend to come from countries with strong institutions and high standards of living

Asset freezing, corporate political resources and the Tullock paradox

In 1967, Gordon Tullock asked why firms do not spend more on campaign contributions, despite the large rents that could be generated from political activities. We suggest in this paper that part of the puzzle could come from the fact that one important type of political activity has been neglected by the literature which focuses on campaign contributions or political connections. We call this neglected activity "asset freezing": situations in which firms delay lay-offs or invest in specific technologies to support local politicians' re-election objectives. In doing so, firms bear a potentially significant cost as they do not use a portion of their economic assets in the most efficient or productive way. The purpose of this paper is to provide a first theoretical exploration of this phenomenon. Building on the literature on corporate political resources, we argue that a firm's economic assets can be evaluated based on their degree of "political freezability," which depends on the flexibility of their use and on their value for policy-makers. We then develop a simple model in which financial contributions and freezing assets are alternative options for a firm willing to lawfully influence public policy-making, and derive some of our initial hypotheses more formally

The political economy of international regulatory convergence in public utilities

To what extent should public utilities regulation be expected to converge across countries? When it occurs, will it generate good outcomes? Building on the core proposition of the New Institutional Economics that similar regulations generate different outcomes depending on their fit with the underlying domestic institutions, we develop a simple model and explore its implications by examining the diffusion of local loop unbundling (LLU) regulations. We argue that: one should expect some convergence in public utility regulation but with still a significant degree of local experimentation; this process will have very different impacts of regulation

International Expansion, Diversification and Regulated Firm Nonmarket Strategy

Previous studies have shown that regulated firms diversify for reasons that are different than for unregulated firms. We explore some of these differences by providing a theoretical model that starts by considering the firm-regulator relationship as an incomplete information issue, in which a regulated incumbent has knowledge that the regulator does not have, but the firm cannot convey hard information about this knowledge. The incumbent faces both market and nonmarket competition from a new entrant. In that context, we show that when the firm faces tough nonmarket competition domestically, going abroad can create a mechanism that makes information transmission to the regulator more credible. International expansion can thus be a way to solve domestic nonmarket issues in addition to being a catalyst for growth

Corporate political activity and firm outcomes: A meta-analysis

Using meta-analytic methods on a sample of 74 studies, we explore the links between CPA and public policy outcomes, and between CPA and firm outcomes. We find that CPA has at best a weak effect and that it appears to be better at maintaining public policy than changing them

Political market and regulatory uncertainty: Insights and implications for integrated strategy

Managers can craft effective integrated strategy by properly assessing regulatory uncertainty. Leveraging the existing political markets literature, we predict regulatory uncertainty from the novel interaction of demand and supply side rivalries across a range of political markets. We argue for two primary drivers of regulatory uncertainty: ideology-motivated interests opposed to the firm and a lack of competition for power among political actors supplying public policy. We align three, previously disparate dimensions of nonmarket strategy - profile level, coalition breadth, and pivotal target - to levels of regulatory uncertainty. Through this framework, we demonstrate how and when firms employ different nonmarket strategies. To illustrate variation in nonmarket strategy across levels of regulatory uncertainty, we analyze several market entry decisions of foreign firms operating in the global telecommunications sector

Central Acceptance Testing for Camera Technologies for CTA

The Cherenkov Telescope Array (CTA) is an international initiative to build the next generation ground based very-high energy gamma-ray observatory. It will consist of telescopes of three different sizes, employing several different technologies for the cameras that detect the Cherenkov light from the observed air showers. In order to ensure the compliance of each camera technology with CTA requirements, CTA will perform central acceptance testing of each camera technology. To assist with this, the Camera Test Facilities (CTF) work package is developing a detailed test program covering the most important performance, stability, and durability requirements, including setting up the necessary equipment. Performance testing will include a wide range of tests like signal amplitude, time resolution, dead-time determination, trigger efficiency, performance testing under temperature and humidity variations and several others. These tests can be performed on fully-integrated cameras using a portable setup at the camera construction sites. In addition, two different setups for performance tests on camera sub-units are being built, which can provide early feedback for camera development. Stability and durability tests will include the long-term functionality of movable parts, water tightness of the camera housing, temperature and humidity cycling, resistance to vibrations during transport or due to possible earthquakes, UV-resistance of materials and several others. Some durability tests will need to be contracted out because they will need dedicated equipment not currently available within CTA. The planned test procedures and the current status of the test facilities will be presented.Comment: 8 pages, 3 figures. In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589