Imaging coherent transport in graphene (Part II): Probing weak localization

Graphene has opened new avenues of research in quantum transport, with potential applications for coherent electronics. Coherent transport depends sensitively on scattering from microscopic disorder present in graphene samples: electron waves traveling along different paths interfere, changing the total conductance. Weak localization is produced by the coherent backscattering of waves, while universal conductance fluctuations are created by summing over all paths. In this work, we obtain conductance images of weak localization with a liquid-He-cooled scanning probe microscope, by using the tip to create a movable scatterer in a graphene device. This technique allows us to investigate coherent transport with a probe of size comparable to the electron wavelength. Images of magnetoconductance \textit{vs.} tip position map the effects of disorder by moving a single scatterer, revealing how electron interference is modified by the tip perturbation. The weak localization dip in conductivity at B=0 is obtained by averaging magnetoconductance traces at different positions of the tip-created scatterer. The width $\Delta B_{WL}$ of the dip yields an estimate of the electron coherence length $L_\phi$ at fixed charge density. This "scanning scatterer" method provides a new way of investigating coherent transport in graphene by directly perturbing the disorder configuration that creates these interferometric effects.Comment: 18 pages, 7 figure

Dynamic tooth loads and stressing for high contact ratio spur gears

An analysis and computer program were developed for calculating the dynamic gear tooth loading and root stressing for high contact ratio gearing (HCRG) as well as LCRG. The analysis includes the effects of the variable tooth stiffness during the mesh, tooth profile modification, and gear errors. The calculation of the tooth root stressing caused by the dynamic gear tooth loads is based on a modified Heywood gear tooth stress analysis, which appears more universally applicable to both LCRG and HCRG. The computer program is presently being expanded to calculate the tooth contact stressing and PV values. Sample application of the gear program to equivalent LCRG (1.566 contact ratio) and HCRG (2.40 contact ratio) revealed the following: (1) the operating conditions and dynamic characteristics of the gear system an affect the gear tooth loading and root stressing, and therefore, life significantly; (2) the length of the profile modification affect the tooth loading and root stressing significantly, the amount depending on the applied load, speed, and contact ratio; and (3) the effect of variable tooth stiffness is small, shifting and increasing the response peaks slightly from those for constant tooth stiffness

Is Pomalidomide Plus Low Dose Dexamethasone an Effective and Safe Treatment for Patients With Relapsed or Refractory Multiple Myeloma?

Objective: The objective of this selective EBM review is to determine whether or not pomalidomide plus low dose Dexamethasone is an effective and safe treatment for patients with relapsed or refractory multiple myeloma (RRMM). Study Design: Review of three open-label clinical trials with one published in 2012 and two published in 2013. Data Sources: Two randomized, open-label, phase 2 clinical trials and one open-label phase 3 clinical trial evaluating efficacy of pomalidomide plus low dose dexamethasone and its safety were found using the PubMed database. Outcomes Measured: Efficacy of pomalidomide plus low-dose dexamethasone was measured by overall response rates (ORR) to the treatment according to the International Myeloma Working Group Criteria/European Group for Blood and Marrow Transplantation criteria.9,10 Safety profile of the treatment regiment was assessed through measuring ANC looking for neutropenia. Results: The studies by Richardson, et al. and Miguel et al. found pomalidomide plus low-dose dexamethasone led to an increased number of patients responding to treatment compared to controls as well as decreased cases of neutropenia.3,4 The study by Leleu et. al. found the 28 day cycle of pomalidomide plus weekly 40 mg of dexamethasone with pomalidomide on days 1-21 had a more favorable safety profile for patients compared to pomalidomide on days 1-28.2 Conclusions: Based on analysis of these 3 randomized controlled trials, pomalidomide plus low dose dexamethasone is a safe and effective treatment option for RRMM. The open-label design of these studies warrants further follow-up with patients who are continuing with these studies to further verify the results established in these reviews

Coaxial Atomic Force Microscope Tweezers

We demonstrate coaxial atomic force microscope (AFM) tweezers that can trap and place small objects using dielectrophoresis (DEP). An attractive force is generated at the tip of a coaxial AFM probe by applying a radio frequency voltage between the center conductor and a grounded shield; the origin of the force is found to be DEP by measuring the pull-off force vs. applied voltage. We show that the coaxial AFM tweezers (CAT) can perform three dimensional assembly by picking up a specified silica microsphere, imaging with the microsphere at the end of the tip, and placing it at a target destination.Comment: 9 pages, 3 figures, in review at Applied Physics Letter

How Brand Identity and Consumer Perception Influences the Marketing Strategies of the Apple Company

The research in this paper focuses on the roles of brand identity and consumer perception in shaping Apple’s marketing strategies and to what extent they are influenced. From going nearly bankrupt to becoming one of the largest companies in the world and a leader in the technology industry, Apple has leveraged its brand identity as a powerful tool to influence consumer perception. The Apple company focuses on its brand identity and has emphasized communicating it to its consumers. While many companies focus on a single aspect of its brand identity, Apple takes a holistic approach by ensuring every aspect of its brand identity complements each other. Apple ensures its brand identity is present in its physical products, marketing campaigns, customer experience, and employees themselves. Apple’s brand identity emphasizes the qualities of simplicity, innovativeness, exclusivity, and memorability within the minds of its consumers. This research is examined through the lens of the 5 P’s of marketing: Product, Price, Place, Promotion, and People