Super-Poissonian noise in a Coulomb blockade metallic quantum dot structure

The shot noise of the current through a single electron transistor (SET), coupled capacitively with an electronic box, is calculated, using the master equation approach. We show that the noise may be sub-Poissonian or strongly super-Poissonian, depending mainly on the box parameters and the gate. The study also supports the idea that not negative differential conductance, but charge accumulation in the quantum dot, responds for the super-Poissonian noise observed.Comment: 4 Pages, 3 Figure

The A-decomposability of the Singer construction

Let $R_s M$ denote the Singer construction on an unstable module $M$ over the Steenrod algebra $A$ at the prime two; $R_s M$ is canonically a subobject of $P_s\otimes M$, where $P_s$ is the polynomial algebra on s generators of degree one. Passage to $A$-indecomposables gives the natural transformation $R_s M \rightarrow F \otimes_A (P_s \otimes M)$, which identifies with the dual of the composition of the Singer transfer and the Lannes-Zarati homomorphism. The main result of the paper proves the weak generalized algebraic spherical class conjecture, which was proposed by the first named author. Namely, this morphism is trivial on elements of positive degree when s>2. The condition s>2 is necessary, as exhibited by the spherical classes of Hopf invariant one and those of Kervaire invariant one.Comment: v2 15 pages. Minor revision. v3 17 pages, revision following referee's recommendations. Accepted for publication J. Al

Risk and Visibility in Global Supply Chains: An Empirical Study

Working with international suppliers in global supply chains, manufacturing firms now are faced with substantial supplier risks which could be triggered by disruptions in either their suppliers or the supplier’s market. Reactive actions to the risks, however, have usually been shown to be inefficient and sometimes ineffective. In this dissertation, therefore, I develop a theoretical framework linking some key relationship-specific capabilities to supplier risk. My contention is that the capabilities, when developed, can help proactively mitigate the risk. Thus, the model in this study is grounded in the resource-based and the relational views. In this study, the survey method has been employed to collect data from 66 manufacturing firms in the United State who are sourcing from international suppliers. Procedural and statistical methods have been employed to guard against typical empirical issues including non-response bias, common method bias, and problems in validity and reliability of measurement instruments. Structural equation modeling with partial least squares was employed to test the model with bootstrapping to estimate t-values for the paths. The analysis results showed support for the model. A conclusion from the study is that visibility is the critical relationship-specific capability that needs to develop for buying firms to mitigate supplier risk proactively. This is because it may not be substitutable by other mechanisms like goodwill trust, and other capabilities, including absorptive capacity and IT integration, will only operate via visibility to influence risk performance. Moreover, visibility is a significant capability that helps mitigate risk regardless of the relationship duration between the buyer and the supplier and of the market conditions under which the supplier is working. This study thus adds to the risk literature with discussions of supplier risks. Nuances have also been added to the resource-based and relational views by developing the theoretical relationships among the identified capabilities and by examining the contextual conditions under which the relationships are working to mitigate supplier risk. Managers from both sides of a dyadic relationship may benefit from the study by utilizing the tools and the study results to monitor and mitigate supplier risk

Enhanced thermoelectric figure of merit in vertical graphene junctions

In this work, we investigate thermoelectric properties of junctions consisting of two partially overlapped graphene sheets coupled to each other in the cross-plane direction. It is shown that because of the weak van-der Waals interactions between graphene layers, the phonon conductance in these junctions is strongly reduced, compared to that of single graphene layer structures, while their electrical performance is weakly affected. By exploiting this effect, we demonstrate that the thermoelectric figure of merit can reach values higher than 1 at room temperature in junctions made of gapped graphene materials, for instance, graphene nanoribbons and graphene nanomeshes. The dependence of thermoelectric properties on the junction length is also discussed. This theoretical study hence suggests an efficient way to enhance thermoelectric efficiency of graphene devices.Comment: 6 pages, 4 figures, submitte