Spontaneous Symmetry Breaking in Two Coupled Nanomechanical Electron Shuttles

We present spontaneous symmetry breaking in a nanoscale version of a setup prolific in classical mechanics: two coupled nanomechanical pendulums. The two pendulums are electron shuttles fabricated as nanopillars and placed between two capacitor plates in a homogeneous electric field. Instead of being mechanically coupled through a spring they exchange electrons, i.e. they shuttle electrons from the source to the drain 'capacitor plate'. Nonzero DC current through this system by external AC excitation is caused via dynamical symmetry breaking. This symmetry-broken current appears at sub- and superharmonics of the fundamental mode of the coupled system

Coulomb Blockade in a Coupled Nanomechanical Electron Shuttle

We demonstrate single electron shuttling through two coupled nanomechanical pendula. The pendula are realized as nanopillars etched out of the semiconductor substrate. Coulomb blockade is found at room temperature, allowing metrological applications. By controlling the mechanical shuttling frequency we are able to validate the different regimes of electron shuttling

Economy and Empire in Making the British-Irish Union, 1756-1801

In contrast to previous scholarship, which emphasizes the passing of the union in the period after 1798 or understands the union as an outcome of long-term British politically integrative tendency, this dissertation argues that the British-Irish union of 1801 had economic foundations. It also explains the union as a culmination of Britain’s economic integration of Ireland within the imperial economy, from the suspensions of the Cattle Acts in 1758 through the acquisition of free trade in 1780 to the union of 1801. A variety of economic arguments – which disagreed on the assessment of the importance on the economy of raw materials, wages, taxes, industriousness, skill, capital, morals, and consumption – shaped in different political and social contexts the suspensions of the Cattle Acts, the Irish free trade, and the union. The Pitt ministry emphasized economic strength in capital, skill, industriousness, and morals that would ensure British superiority despite heavier taxes and wages. In the union, they introduced temporary protective duties for Ireland, rested the union between Britain and Ireland on the foundations of landed proprietors, and sought to civilize the Irish with their allegedly superior British morals. Identity was promoted in a number of different but overlapping ways in the British Isles. The intricacies and complexities of Englishness, Britishness, and Irishness, whose identity formations depended on Englishness and the polity, shaped the suspensions of the Cattle Acts, Irish parliamentary independence, and the union. The invention of Jacobinism as immoral, irreligious, propertyless, and French in Britain, which was biased in favor of British loyalists and different from the reality of Jacobinism in France, however, politically repressed the other versions of British and Irish identities. When it came to the union, Britishness developed into the identity of the British empire by contrasting itself with the “otherness” of Jacobinism. The Pitt ministry disproportionately augmented the parliamentary representation of landed proprietors against propertyless Jacobins and more democratic reformism. A propertied polity through the union was to be the source of a new order and to consolidate and unite the British empire

Realizing broadbands of strong nonlinear coupling in nanoelectromechanical electron shuttles

We demonstrate the transition of a coupled electron shuttle from a stable to a strongly nonlinear response at room temperature. Within this transition we observe the coupled shuttle's response to change from Coulomb controlled to conventional field emission. This parametric process is fully reversible and occurs within a broad frequency range. In combination, the large current and wide frequency band enable energy harvesting applications. The experimental data and the numerical calculations both indicate that the source of the nonlinearity is given by the electromechanical coupling of electron shuttling. © 2013 American Physical Society.The authors would like to thank the Defense Advanced Research Projects Agency (DARPA) for support through the NEMS-CMOS Program (No. N66001-07-1-2046), the University of Wisconsin-Madison for support by a Draper-TIF Award, the Wisconsin Alumni Research Foundation (WARF) for a Clean Tech Grant within the Accelerator Program, the Spanish Ministry of Education [Programs No. SB2009-007, No. MAT 2011-24331 and ITN, Grant No. 234970 (EU)] and the Korea Institute of Science and Technology (KIST) for support through the KIST Institutional program (2V03030) and the KIST Future Fundamental Research Program.Peer Reviewe

Underground Parking Lot Navigation System Using Long-Term Evolution Signal

Some of the shopping malls, airports, hospitals, etc. have underground parking lots where hundreds of vehicles can be parked. However, first-time visitors find it difficult to determine their current location and need to keep moving the vehicle to find an empty parking space. Moreover, they need to remember the parked location, and find a nearby staircase or elevator to move toward the destination. In such a situation, if the user location can be estimated, a new navigation system can be offered, which can assist users. This study presents an underground parking lot navigation system using long-term evolution (LTE) signals. As the proposed system utilizes LTE network signals for which the infrastructure is already installed, no additional infrastructure is required. To estimate the location of the vehicle, the signal strength of the LTE signal is accumulated, and the location of the vehicle is estimated by comparing it with the previously stored database of the LTE received signal strength (RSS). In addition, the acceleration and gyroscope sensors of a smartphone are used to improve the vehicle position estimation performance. The effectiveness of the proposed system is verified by conducting an experiment in a large shopping-mall underground parking lot where approximately 500 vehicles can be parked. From the results of the experiment, an error of less than an average of 10 m was obtained, which shows that seamless navigation is possible using the proposed system even in an environment where GNSS does not function

Pattern Recognition for Selective Odor Detection with Gas Sensor Arrays

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Transition of a nanomechanical Sharvin oscillator towards the chaotic regime

Werealize a nanomechanical impact oscillator driven by a radiofrequency signal. The mechanical impact of the oscillator is demonstrated by increasing the amplitude of the external radiofrequency signals. Electron transport in the system is dramatically modified when the oscillator is strongly driven to undergo forced impacts with electrodes.Weexploit this nonlinear kind of electron transport to observe the current response in the chaotic regime. Our model adopting the Sharvin conductance at the moment of impact provides a description of the rectified current via the impact oscillator in the linear regime, revealing a path towards chaos. ©2017 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft111sciescopu

Evaluation of Chemical Interactions between Small Molecules in the Gas Phase Using Chemical Force Microscopy

Chemical force microscopy analyzes the interactions between various chemical/biochemical moieties in situ. In this work we examined force-distance curves and lateral force to measure the interaction between modified AFM tips and differently functionalized molecular monolayers. Especially for the measurements in gas phase, we investigated the effect of humidity on the analysis of force-distance curves and the images in lateral force mode. Flat chemical patterns composed of different functional groups were made through micro-contact printing and lateral force mode provided more resolved analysis of the chemical patterns. From the images of 1-octadecanethiol/11-mercapto-1-undecanoic acid patterns, the amine group functionalized tip brought out higher contrast of the patterns than an intact silicon nitride tip owing to the additional chemical interaction between carboxyl and amine groups. For more complex chemical interactions, relative chemical affinities toward specific peptides were assessed on the pattern of 1-octadecanethiol/phenyl-terminated alkanethiol. The lateral image of chemical force microscopy reflected specific preference of a peptide to phenyl group as well as the hydrophobic interaction