Boston College

About: Boston College is a education organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 9749 authors who have published 25406 publications receiving 1105145 citations. The organization is also known as: BC.

Enhancement of Thermoelectric Figure-of-Merit by a Bulk Nanostructuring Approach

Abstract: Recently a significant figure-of-merit (ZT) improvement in the most-studied existing thermoelectric materials has been achieved by creating nanograins and nanostructures in the grains using the combination of high-energy ball milling and a direct-current-induced hot-press process. Thermoelectric transport measurements, coupled with microstructure studies and theoretical modeling, show that the ZT improvement is the result of low lattice thermal conductivity due to the increased phonon scattering by grain boundaries and structural defects. In this article, the synthesis process and the relationship between the microstructures and the thermoelectric properties of the nanostructured thermoelectric bulk materials with an enhanced ZT value are reviewed. It is expected that the nanostructured materials described here will be useful for a variety of applications such as waste heat recovery, solar energy conversion, and environmentally friendly refrigeration.

Shaping Abortion Discourse: Democracy and the Public Sphere in Germany and the United States

Abstract: Tables and figures Foreword Friedhelm Neidhardt Preface Glossary Part I Introduction: 1 Two related stories 2 Historical context 3 Methods Part II Major Outcomes: 4 The discursive opportunity structure 5 Standing 6 Framing Part III Representing Different Constituencies: 7 Representing women's claims 8 Representing religious claims 9 Representing the tradition of the left Part IV The Quality of Abortion Discourse: 10 Normative criteria for the public sphere 11 Measuring the quality of discourse 12 Metatalk 13 Lessons for democracy and the public sphere Methodological appendix References Index

What's different about social media networks? a framework and research agenda

Abstract: In recent years, we have witnessed the rapid proliferation and widespread adoption of a new class of information technologies, commonly known as social media. Researchers often rely on social network analysis (SNA) when attempting to understand these technologies, often without considering how the novel capabilities of social media platforms might affect the underlying theories of SNA, which were developed primarily through studies of offline social networks. This article outlines several key differences between traditional offline social networks and online social media networks by juxtaposing an established typology of social network research with a well-regarded definition of social media platforms that articulates four key features. The results show that at four major points of intersection, social media has considerable theoretical implications for SNA. In exploring these points of intersection, this study outlines a series of theoretically distinct research questions for SNA in social media contexts. These points of intersection offer considerable opportunities for researchers to investigate the theoretical implications introduced by social media and lay the groundwork for a robust social media agenda potentially spanning multiple disciplines.

Experimental demonstration of frequency-agile terahertz metamaterials

Abstract: Metamaterials exhibit numerous novel effects1,2,3,4,5 and operate over a large portion of the electromagnetic spectrum6,7,8,9,10. Metamaterial devices based on these effects include gradient-index lenses11,12, modulators for terahertz radiation13,14,15 and compact waveguides16. The resonant nature of metamaterials results in frequency dispersion and narrow bandwidth operation where the centre frequency is fixed by the geometry and dimensions of the elements comprising the metamaterial composite. The creation of frequency-agile metamaterials would extend the spectral range over which devices function and, further, enable the manufacture of new devices such as dynamically tunable notch filters. Here, we demonstrate such frequency-agile metamaterials operating in the far-infrared by incorporating semiconductors in critical regions of metallic split-ring resonators. For this first-generation device, external optical control results in tuning of the metamaterial resonance frequency by ∼20%. Our approach is integrable with current semiconductor technologies and can be implemented in other regions of the electromagnetic spectrum. Metamaterials that possess frequency tunability enable new device functions. By external optical control through the incorporation of semiconductors in metallic split-ring resonators, the researchers provide an elegant solution to frequency-agile terahertz metamaterials.