Analysis of Possible Quantum Metastable States in Ballistic Graphene-based Josephson Junctions

Graphene is a relatively new material (2004) made of atomic layers of carbon arranged in a honeycomb lattice. Josephson junction devices are made from graphene by depositing two parallel superconducting leads on a graphene flake. These devices have hysteretic current-voltage characteristics with a supercurrent branch and Shapiro steps appear when irradiated with microwaves. These properties motivate us to investigate the presence of quantum metastable states similar to those found in conventional current-biased Josephson junctions. We present work investigating the nature of these metastable states for ballistic graphene Josephson junctions. We model the effective Washboard potential for these devices and estimate parameters, such as energy level spacing and critical currents, to deduce the design needed to observe metastable states. We propose devices consisting of a parallel on-chip capacitor and suspended graphene. The capacitor is needed to lower the energy level spacing down to the experimentally accessible range of 1-20 GHz. The suspended graphene helps reduce the noise that may otherwise come from two-level states in the insulating oxide layer. Moreover, back-gate voltage control of its critical current introduces another knob for quantum control. We will also report on current experimental progress in the area of fabrication of this proposed device.Comment: 4 pages, 5 figures, Accepted for publication in IEEE Transactions on Applied Superconductivity from ASC 2010. Additional figures, additional calculation

Alien Registration- Lambert, Joseph (Augusta, Kennebec County)

https://digitalmaine.com/alien_docs/18462/thumbnail.jp

Differential Conductance Measurements of MgB2-Based Josephson Junctions Below 1 Kelvin

Magnesium diboride has many intriguing characteristics, including its relatively high critical temperature and two-band nature. Most prior studies of MgB2 thin film Josephson junctions have been conducted above 2 Kelvin. We report results of sub-1 Kelvin experiments of MgB2/insulator/Pb junctions whose a-b plane is exposed for electron tunneling. By measuring differential conductance at low temperature, new details in the structure of the sigma- and pi-band gaps are observed in this data, consistent with theoretical predictions.Comment: ASC 2010 Conferenc

A compilation, tabulation and analysis of spelling errors in grade six

Thesis (Ed.M.)--Boston Universit

Evaluating Engagement in Digital Narratives from Facial Data

Engagement researchers indicate that the engagement level of people in a narrative has an influence on people's subsequent story-related attitudes and beliefs, which helps psychologists understand people's social behaviours and personal experience. With the arrival of multimedia, the digital narrative combines multimedia features (e.g. varying images, music and voiceover) with traditional storytelling. Research on digital narratives has been widely used in helping students gain problem-solving and presentation skills as well as supporting child psychologists investigating children's social understanding such as family/peer relationships through completing their digital narratives. However, there is little study on the effect of multimedia features in digital narratives on the engagement level of people. This research focuses on measuring the levels of engagement of people in digital narratives and specifically on understanding the media effect of digital narratives on people's engagement levels. Measurement tools are developed and validated through analyses of facial data from different age groups (children and young adults) in watching stories with different media features of digital narratives. Data sources used in this research include a questionnaire with Smileyometer scale and the observation of each participant's facial behaviours

A Techno-Economic Assessment of Shipping Through the Arctic

The Arctic Ocean is experiencing considerable and adverse environmental change driven by global warming. Global warming is inducing Arctic ice to melt and recede, facilitating increased accessibility for ships to transit through. Arctic shipping routes are shorter than their counterparts the Suez and Panama Canal routes. For the same origin and destination, a shorter shipping route would enable lower transport costs and an increased volume of trade. In this thesis, the principal contribution is to expand the framing of Arctic shipping feasibility to include costs from emission externalities and assess Arctic shipping feasibility on balance with these externalities. Five scenarios which represent different societal choices and levels of global warming were considered to see how they affect the development of Arctic shipping viability. All ships are treated as newbuilds, alternative fuelled ships are assumed to have the machinery retrofitted on top of the newbuild design. A dimensionless metric was proposed to enable a comparison of Arctic shipping feasibility between the different scenarios in the years 2020, 2035 and 2050. Including emission damages increased the feasibility of Arctic shipping due to the lower damages associated with air pollution in the Arctic and a lower intensity of emissions. However, only externalities from a select number of emission species were considered which means that the considered environmental costs are an underestimate. The veracity of increased feasibility is discussed. A deterministic analysis was complemented with a stochastic assessment to address uncertainties and show that Arctic shipping probably becomes economically feasible for container shipping and infeasible for dry bulkers across all scenarios. Mixed results were returned for tankers. A sensitivity analysis found that the most significant variables that determine Arctic shipping feasibility were the cost of carbon, engine load and route lengths. This thesis concludes with a discussion on the implications of these results

Sensitivity of Human Choice to Manipulations of Parameters of Positive and Negative Sound Reinforcement

The purpose of this study was to determine whether altering parameters of positive and negative reinforcement in identical ways could influence behavior maintained by each in different ways. Three undergraduate students participated in a series of assessments designed to identify preferred and aversive sounds with similar reinforcing values. Following reinforcer identification, we conducted parameter sensitivity assessments for both positive and negative reinforcers. Parameter manipulations influenced behavior in the same way across reinforcement processes for two participants. However, for one participant, the way in which parameter manipulations influenced behavior differed according to the reinforcement process. Our results suggest that, for at least some individuals, positive and negative sound reinforcement processes do not influence behavior in identical ways. Clinical and theoretical implications are discussed