Nonlinear viscoelastic characterization of structural adhesives

Measurements of the nonliner viscoelastic behavior of two adhesives, FM-73 and FM-300, are presented and discussed. Analytical methods to quantify the measurements are given and fitted into a framework of an accelerated testing and analysis procedure. The single integral model used is shown to function well and is analogous to a time-temperature stress-superposition procedure (TTSSP). Advantages and disadvantages of the creep power law method used in this study are given

The Lessons of “Lesson Drawing”: How the Obama Administration Attempted to Learn from Failure of the Clinton Health Plan

The article examines the role of historical insights in the creation of U.S. healthcare policy. Particular focus is given to the influence of former U.S. President Bill Clinton\u27s 1993-1994 attempts at healthcare reform on the policies of U.S. President Barack Obama. It is suggested that while the U.S. Patient Protection and Affordable Care act of 2010 was successful in many respects, the Obama administration\u27s efforts to avoid missteps taken with Clinton\u27s Health Security Act did not significantly aid and sometimes even hindered its progress. Details on the political strategy, policy design, and political rhetoric used by both administrations are presented. Other topics include partisan politics and the communication of policy goals to the public

Electron transport in semiconducting carbon nanotubes with hetero-metallic contacts

We present an atomistic self-consistent study of the electronic and transport properties of semiconducting carbon nanotube in contact with metal electrodes of different work functions, which shows simultaneous electron and hole doping inside the nanotube junction through contact-induced charge transfer. We find that the band lineup in the nanotube bulk region is determined by the effective work function difference between the nanotube channel and source/drain electrodes, while electron transmission through the SWNT junction is affected by the local band structure modulation at the two metal-nanotube interfaces, leading to an effective decoupling of interface and bulk effects in electron transport through nanotube junction devices.Comment: Higher quality figures available at http://www.albany.edu/~yx15212

Interference effects in electronic transport through metallic single-wall carbon nanotubes

In a recent paper Liang {\it et al.} [Nature {\bf 411}, 665 (2001)] showed experimentally, that metallic nanotubes, strongly coupled to external electrodes, may act as coherent molecular waveguides for electronic transport. The experimental results were supported by theoretical analysis based on the scattering matrix approach. In this paper we analyze theoretically this problem using a real-space approach, which makes it possible to control quality of interface contacts. Electronic structure of the nanotube is taken into account within the tight-binding model. External electrodes and the central part (sample) are assumed to be made of carbon nanotubes, while the contacts between electrodes and the sample are modeled by appropriate on-site (diagonal) and hopping (off-diagonal) parameters. Conductance is calculated by the Green function technique combined with the Landauer formalism. In the plots displaying conductance {\it vs.} bias and gate voltages, we have found typical diamond structure patterns, similar to those observed experimentally. In certain cases, however, we have found new features in the patterns, like a double-diamond sub-structure.Comment: 15 pages, 4 figures. To apear in Phys. Rev.

Framing and Claiming the Homelessness Problem

Despite a recent upsurge of interest in the issue, homelessness is a problem of long standing in American society. This article traces how several forces catalyzed the problem\u27s re-entrance onto the political agenda in the 1980s. It then reviews the ongoing debate over homelessness causes and cures as a struggle for problem ownership that has complicated the choices of public policymakers. The final section examines various descriptive attributes that figure into the dispute over how to define homelessness and influence the nature of the public policy response to it

Computational Models of Adult Neurogenesis

Experimental results in recent years have shown that adult neurogenesis is a significant phenomenon in the mammalian brain. Little is known, however, about the functional role played by the generation and destruction of neurons in the context of and adult brain. Here we propose two models where new projection neurons are incorporated. We show that in both models, using incorporation and removal of neurons as a computational tool, it is possible to achieve a higher computational efficiency that in purely static, synapse-learning driven networks. We also discuss the implication for understanding the role of adult neurogenesis in specific brain areas.Comment: To appear Physica A, 7 page

Conductance of Distorted Carbon Nanotubes

We have calculated the effects of structural distortions of armchair carbon nanotubes on their electrical transport properties. We found that the bending of the nanotubes decreases their transmission function in certain energy ranges and leads to an increased electrical resistance. Electronic structure calculations show that these energy ranges contain localized states with significant $\sigma$-$\pi$ hybridization resulting from the increased curvature produced by bending. Our calculations of the contact resistance show that the large contact resistances observed for SWNTs are likely due to the weak coupling of the NT to the metal in side bonded NT-metal configurations.Comment: 5 pages RevTeX including 4 figures, submitted to PR

Enhanced thermal stability and spin-lattice relaxation rate of N@C60 inside carbon nanotubes

We studied the temperature stability of the endohedral fullerene molecule, N@C60, inside single-wall carbon nanotubes using electron spin resonance spectroscopy. We found that the nitrogen escapes at higher temperatures in the encapsulated material as compared to its pristine, crystalline form. The temperature dependent spin-lattice relaxation time, T_1, of the encapsulated molecule is significantly shorter than that of the crystalline material, which is explained by the interaction of the nitrogen spin with the conduction electrons of the nanotubes.Comment: 5 pages, 4 figures, 1 tabl

Femmes au masculin : Jane Dieulafoy et Marc de Montifaud

Les photographies issues d\u27une collection unique en son genre, celle de la bibliothèque Marguerite Durand, nous convient à une traversée en pointillé de cent cinquante ans d\u27histoire des femmes, des années 1860 aux années MLF. Portraits, photographies d\u27art ou documentaires révèlent quelques-unes des grandes aventures collectives de la vie des femmes, celles du travail, des arts et de leurs mobilisations pour leur libération. Ce parcours en images met en lumière la double perspective de la collection depuis sa création : rendre visibles les femmes présentes dans l\u27espace public, actives dans des domaines traditionnellement réservés aux hommes et archiver les témoignages de leurs combats, encore inachevés. Restituer ces multiples regards invite à une écriture du passé qui accorde à l\u27émancipation des femmes toute son importance, décisive dans la conquête de l\u27égalité et de liberté de tous.