Correlation-induced resonances and population switching in a quantum dot coulomb valley

Strong correlation effects on electron transport through a spinless quantum dot are considered. When two single-particle levels in the quantum dot are degenerate, a conserved pseudospin degree of freedom appears for general tunneling matrix elements between the quantum dot and leads. Local fluctuations of the pseudospin in the quantum dot give rise to a pair of asymmetric conductance peaks near the center of a Coulomb valley. An exact relation to the population switching is provided.Comment: Fig. 4 and some technical details removed. To appear in PR

iSchools and Social Identity ??? A Social Network Analysis

We analyze the publication co-authorship network of an iSchool faculty community using ???Social Identity Theory??? as the theoretical lens. Initially, we discuss the need for a theoretical framework to analyze and interpret social network data. Then, we find out the patterns in the levels of interaction happening within the faculty community at an inter-group level. We grouped faculty members into different clusters according to several parameters such as their educational backgrounds, affiliations with research centers/labs, and h-indices. We based our analysis on this classification and we try to understand the relationship among social identity, group affiliation and academic collaborations. We conclude with the remarks that one could avoid idiosyncratic ways of interpreting social network data by using a proven theoretical lens like ???Social Identity Theory??

Development of Tangible Code Blocks for the Blind and Visually Impaired

The fields of Science, Technology, Engineering, and Mathematics (STEM) have been growing at an accelerating rate in recent times. Knowing how to program has become one key skill for entering all of these STEM fields. However, many students find programming difficult. The block based programming language, Scratch, was specifically designed to lower hurdles to learning how to program for sighted students. Unfortunately, although very effective and widely used in K12 classrooms, Scratch, similar to other block based languages, is inaccessible to students who are blind and visually impaired (BVI). This thesis is part of a larger project to make the Scratch environment accessible to BVI students. The focus of this thesis is on creating a tangible code block design that: 1) is accessible to BVIs, 2) retains the reduced need to struggle with syntax of Scratch, 3) allows code construction through action, 4) and co-construction with other BVI and sighted students, and 5) can create moderately sized programs at low cost. The first several parts of this thesis consider the design and assessment process for the code blocks, which went through two iterations. The four major components of the first design iteration were: 1) the use of passive blocks, with use of 2) the local edge shape connectivity between blocks defining the program syntax, 3) telescoping tubing to allow nested expressions when valid, and 4) haptically legible commands for both Braille and non-Braille users. The first iteration of the block design was compared to a text based method in building and correcting operator expressions that included both simple and nested expressions of the arithmetic, relational and logical operators. BVI participants produced correct code significantly more when doing the tasks with the code blocks than with the text method. Although the text method was faster, it did not account for any additional time that would be needed to identify and change incorrect code before a program could be run. One weakness of the first iteration was that it was difficult for BVI participants to easily determine connectivity between validly connecting code blocks. The second design iteration considered the effect of embedding different degrees of magnetic attraction within the local shape connection to improve identification of the connectivity. It also considered how to represent some commands that had additional restrictions to those found with most of the other code block types. In particular, we considered the use of different “stopper” designs to prevent numeric literals from being placed in the left slot of a “set” command, which could only accept a variable. Results from a set of studies evaluating the ability of BVI participants to identify the connectivity between blocks found that the magnetic attraction within the connection significantly improved accuracy and ease of use, with the stronger magnetic connections preferred. They also found that a stopper design could be used for “exceptions”, with the longer stopper aligned with the local connection preferred. The final part of the thesis examines the use of the code blocks by the targeted population (BVI students in middle school) in a classroom setting within the context of the entire nonvisual interface. To do this, two day code camps were conducted with BVI middle school students, and recorded on video and audio. Qualitative content analysis was used to verify that the students interacted with the system as intended by the code block design. Results suggest that the students did interact with the code blocks as intended by the design, but minor improvements should be made to increase their ease of use. Participants did appear to have a positive experience with the code blocks and the system overall

Role of thermal friction in relaxation of turbulent Bose-Einstein condensates

In recent experiments, the relaxation dynamics of highly oblate, turbulent Bose-Einstein condensates (BECs) was investigated by measuring the vortex decay rates in various sample conditions [Phys. Rev. A $\bf 90$, 063627 (2014)] and, separately, the thermal friction coefficient $\alpha$ for vortex motion was measured from the long-time evolution of a corotating vortex pair in a BEC [Phys. Rev. A $\bf 92$, 051601(R) (2015)]. We present a comparative analysis of the experimental results, and find that the vortex decay rate $\Gamma$ is almost linearly proportional to $\alpha$. We perform numerical simulations of the time evolution of a turbulent BEC using a point-vortex model equipped with longitudinal friction and vortex-antivortex pair annihilation, and observe that the linear dependence of $\Gamma$ on $\alpha$ is quantitatively accounted for in the dissipative point-vortex model. The numerical simulations reveal that thermal friction in the experiment was too strong to allow for the emergence of a vortex-clustered state out of decaying turbulence.Comment: 7 pages, 5 figure

Determinants of Mid-scale Hotel Brand Equity

The traditional brand management in the hotel industry is facing a great challenge as numerous brands provide many choices to hotel guests. In such competitive environments, hotel firms realize that capitalizing on one of the most important assests they own- the brand- is critical to achieve a premier growth goal not only rapidly but also in a cost- effective way. THe purpose of this study is to examine the determinants of cutsomer-based hotel brand equity for the mid-priced U.S. lodging segment by assessing the impacts of four-widely accepted brand equity dimensions: brand awareness, brand associations, percieved quality and customer loyalty. 277 travelers participated in this study at the airport in a Midwestern city. Perceived quality, brand loyalty, brand associations were found to be the core components of brand equity, while brand awareness, a seemingly important source of brand equity, did not exert a significant influence on building brand equity of mid-priced hotels. The result of this study sheds insight about how to create, manage, and evaluate a distinctive and successful hotel brand

Effect of ferromagnetic contacts on spin accumulation in an all-metallic lateral spin-valve system: Semiclassical spin drift-diffusion equations

We study the effect of the ferromagnetic (FM) contacts on the spin accumulation in the lateral spin valve system for the collinear magnetization configurations. When an additional FM electrode is introduced in the all-metallic lateral spin-valve system, we find that the transresistance can be fractionally suppressed or very weakly influenced depending on the position of the additional FM electrode, and relative magnitudes of contact resistance and the bulk resistance defined over the spin diffusion length. Nonlocal spin signals such as nonlocal voltage drop and leakage spin currents are independent of the magnetization orientation of the additional FM electrode. Even when the additional contact is nonmagnetic, nonlocal spin signals can be changed by the spin current leaking into the nonmagnetic electrode.Comment: 13 pages, 1 figure, revised versio