Self heating and nonlinear current-voltage characteristics in bilayer graphene

We demonstrate by experiments and numerical simulations that the low-temperature current-voltage characteristics in diffusive bilayer graphene (BLG) exhibit a strong superlinearity at finite bias voltages. The superlinearity is weakly dependent on doping and on the length of the graphene sample. This effect can be understood as a result of Joule heating. It is stronger in BLG than in monolayer graphene (MLG), since the conductivity of BLG is more sensitive to temperature due to the higher density of electronic states at the Dirac point.Comment: 9 pages, 7 figures, REVTeX 4.

Block copolymer self-assembly for nanophotonics

The ability to control and modulate the interaction of light with matter is crucial to achieve desired optical properties including reflection, transmission, and selective polarization. Photonic materials rely upon precise control over the composition and morphology to establish periodic interactions with light on the wavelength and sub-wavelength length scales. Supramolecular assembly provides a natural solution allowing the encoding of a desired 3D architecture into the chemical building blocks and assembly conditions. The compatibility with solution processing and low-overhead manufacturing is a significant advantage over more complex approaches such as lithography or colloidal assembly. Here we review recent advances on photonic architectures derived from block copolymers and highlight the influence and complexity of processing pathways. Notable examples that have emerged from this unique synthesis platform include Bragg reflectors, antireflective coatings, and chiral metamaterials. We further predict expanded photonic capabilities and limits of these approaches in light of future developments of the field

Evaluating the Use of Telehealth to Manage Hypertension in Primary Care

Background: Hypertension remains one of the most common chronic conditions in the United States leading to several health complications and immense financial burdens, yet it remains grossly undertreated despite the availability of evidence-based treatment options. The 2017 guidelines from the American College of Cardiology and American Heart Association recommended the use of home blood pressure monitoring with a telehealth component as an adjunct to regular hypertension treatment; however, implementing this into practice can be difficult depending on the setting, available resources, and the knowledge and skills of the providers. Aims: The purpose of this investigation is to evaluate patient adherence of measuring and logging blood pressure on the electronic medical record patient portal and the provider offering feedback regarding treatment. A secondary aim is to evaluate blood pressure trends of patients pre- and post-intervention. Methods: A retrospective and prospective study was completed to evaluate patient and provider adherence to using the recommended home blood pressure monitoring with telehealth transmission. The goal was for patients to take and log blood pressure daily for a minimum of two weeks. The number of blood pressures used to assess adherence was 12 blood pressures in a one-month period. The provider was expected to follow up anytime within the month period. Change in systolic and diastolic blood pressure was also assessed. Results: Nine patients met the inclusion criteria and all nine patients participated in the telehealth intervention. Six (66.7%) were adherent and logged at least 12 blood pressures, seven (77.8%) logged at least 11 blood pressures and two participants (22.2%) logged no blood pressure measurements. Provider feedback was given to the seven participants (77.8%) who logged data. All patients who logged blood pressure measurements were within goal or near goal at the end of the intervention. Discussion/Implications: High levels of provider and patient adherence to the intervention suggest this intervention was an acceptable and feasible cointervention for the management of hypertension in the primary care setting and could be successful for the other patients with hypertension in this clinic and beyond

A State-By-State Analysis of Inevitable Disclosure: A Need for Uniformity and a Workable Standard

Even after the majority of the states adopted the Uniform Trade Secrets Act, there is a lack of uniformity in their applications of trade secret laws. This lack of uniformity is directly contrary to section 8 of the UTSA, which calls for the uniform application of trade secret laws by the states adopting the Act. Consequently, there is a need for uniformity in the states’ applications of trade secret law, more specifically, the inevitable disclosure doctrine. This Comment will provide a basic introduction to trade secrets, the inevitable disclosure doctrine, including a discussion of the Seventh Circuit’s decision in Pepsico v. Redmond, and the Uniform Trade Secrets Act. Furthermore, this Comment will discuss and analyze the different states’ applications of the inevitable disclosure doctrine. Ultimately, a workable standard for the uniform application of inevitable disclosure will be proposed. In proposing a workable standard, this Comment will argue that the inevitable disclosure doctrine should be applied rarely, and deference should be given to employers that utilize valid employment agreements that are narrowly drafted to specifically protect the employer’s trade secrets. However, in the absence of a valid employment agreement protecting an employer’s trade secrets, an employee should be free to work for an employer of his choosing unless the former employer can prove some kind of bad faith on the part of the employee

Differences in Acoustic Measures of Vowels in Ventriloquial and Normal Speech

This study investigated and compared the acoustic properties of vowels in ventriloquial and normal speech. Voice recordings of a 51 year-old male participant producing 10 words containing target vowels, three times each were made in both normal and ventriloquial speech. Standard acoustic measures for frequency were gathered using Tiger Electronics Inc., Dr. Speech Science, Ver.2.0. Fundamental frequency, first, and second formant frequencies were analyzed as compared between the two types of speech. Although the results revealed no statistically significant differences in first and second formant frequencies, slight variations do exist. Statistically significant differences were found for two words in fundamental frequency. The results would seem to suggest that as long as vowel production is within a “range” of variability, vowels may be accurately perceived

Shot noise and conductivity at high bias in bilayer graphene: Signatures of electron-optical phonon coupling

We have studied electronic conductivity and shot noise of bilayer graphene (BLG) sheets at high bias voltages and low bath temperature $T_0=4.2$ K. As a function of bias, we find initially an increase of the differential conductivity, which we attribute to self-heating. At higher bias, the conductivity saturates and even decreases due to backscattering from optical phonons. The electron-phonon interactions are also responsible for the decay of the Fano factor at bias voltages $V>0.1$ V. The high bias electronic temperature has been calculated from shot noise measurements, and it goes up to $\sim1200$ K at $V=0.75$ V. Using the theoretical temperature dependence of BLG conductivity, we extract an effective electron-optical phonon scattering time $\tau_{e-op}$. In a 230 nm long BLG sample of mobility $\mu=3600$ cm$^2$V$^{-1}$s$^{-1}$, we find that $\tau_{e-op}$ decreases with increasing voltage and is close to the charged impurity scattering time $\tau_{imp}=60$ fs at $V=0.6$ V.Comment: 7 pages, 7 figures. Extended version of the high bias part of version 1. The low bias part is discussed in arXiv:1102.065

Generation of bipartite spin entanglement via spin-independent scattering

We consider the bipartite spin entanglement between two identical fermions generated in spin-independent scattering. We show how the spatial degrees of freedom act as ancillas for the creation of entanglement to a degree that depends on the scattering angle, $\theta$. The number of Slater determinants generated in the process is greater than 1, corresponding to genuine quantum correlations between the identical fermions. The maximal entanglement attainable of 1 ebit is reached at $\theta=\pi/2$. We also analyze a simple $\theta$ dependent Bell's inequality, which is violated for $\pi/4<\theta\leq\pi/2$. This phenomenon is unrelated to the symmetrization postulate but does not appear for unequal particles.Comment: 5 pages and 3 figures. Accepted in PR

Detection of graphene microelectromechanical system resonance

We present an experimental setup for fast detection of resonances of graphene microelectromechanical structures of different quality. The relatively simple technique used to read-out of the resonance frequency is the main advantage of the proposed system. The resolution is good enough to detect vibrations of the graphene resonator with the quality factor of ∼24 and resonance frequency of 104 MHz