Optical response of high-TcT_c cuprates: possible role of scattering rate saturation and in-plane anisotropy

We present a generalized Drude analysis of the in-plane optical conductivity $\sigma_{ab}$($T$,$\omega$) in cuprates taking into account the effects of in-plane anisotropy. A simple ansatz for the scattering rate $\Gamma$($T$,$\omega$), that includes anisotropy, a quadratic frequency dependence and saturation at the Mott-Ioffe-Regel limit, is able to reproduce recent normal state data on an optimally doped cuprate over a wide frequency range. We highlight the potential importance of including anisotropy in the full expression for $\sigma_{ab}$($T$,$\omega$) and challenge previous determinations of $\Gamma$($\omega$) in which anisotropy was neglected and $\Gamma$($\omega$) was indicated to be strictly linear in frequency over a wide frequency range. Possible implications of our findings for understanding thermodynamic properties and self-energy effects in high-$T_c$ cuprates will also be discussed.Comment: 8 pages, 7 figures. To be published in Physical Review

Linear magnetoresistance in a quasi-free two dimensional electron gas in an ultra-high mobility GaAs quantum well

We report a magnetotransport study of an ultra-high mobility ($\bar{\mu}\approx 25\times 10^6$\,cm$^2$\,V$^{-1}$\,s$^{-1}$) $n$-type GaAs quantum well up to 33 T. A strong linear magnetoresistance (LMR) of the order of 10$^5$ % is observed in a wide temperature range between 0.3 K and 60 K. The simplicity of our material system with a single sub-band occupation and free electron dispersion rules out most complicated mechanisms that could give rise to the observed LMR. At low temperature, quantum oscillations are superimposed onto the LMR. Both, the featureless LMR at high $T$ and the quantum oscillations at low $T$ follow the empirical resistance rule which states that the longitudinal conductance is directly related to the derivative of the transversal (Hall) conductance multiplied by the magnetic field and a constant factor $\alpha$ that remains unchanged over the entire temperature range. Only at low temperatures, small deviations from this resistance rule are observed beyond $\nu=1$ that likely originate from a different transport mechanism for the composite fermions

Translation and Validation of the HPLP-II From English to Armenian

As the focus of healthcare shifts toward the social determinants of health, more information about health disparities between different ethnic communities is needed. The Health Promoting Lifestyle Profile II (HPLP-II) is an instrument that measures health promotion behavior across various cultural lines. This article describes the translation and validation of the HPLP-II from English to Armenian for the purpose of studying health promotion behavior among the hypertensive and normotensive Armenian American population and addressing health disparities among this community. Translating the HPLP-II required a multistep process to capture cultural linguistic adjustment. First, the researcher, a local bilingual professor, and a professional translation company each created a forward-translation. These three translations were combined by an editor to create one translation with the highest clarity. The researcher then submitted this translation to two bilingual community members for back-translation. A committee composed of the researcher, the community members, and a bilingual healthcare worker reviewed each back-translated item and adjusted those that lost their meanings. Another committee reviewed each item for clarity and consistency. The instrument was then given to five native speakers who were asked to read each question and verbally express what they understood it to be asking. After the researcher made adjustments based on this feedback, the instrument was given to a committee of nine bilingual experts, who reviewed each item and scored it.This multistep, iterative process resulted in an instrument with an item content validity index score of 0.90 (\u3e0.78) and a scale content validity index of 0.96 (\u3e0.90), and Cronbach’s a = 0.936, suggesting a high level of reliability. The HPLP-II can now be used in future studies regarding health promotion behavior among Armenian Americans

Application Calling

The motivation for the development of Application Calling grew from an interest in offering a large number of users access to software on an AppleTalk network. The goal of Application Calling was to give access to applications and yet: • limit the disk space requirements • protect software vendors from unauthorized copying of software • maintain the standard Macintosh interface • allow for easy software updates Application Calling does this by using a different method of accessing software. Instead of every user having a copy of an application, every user has a copy of a small file which launches or calls up” the real application. The real applications are then hidden so that they cannot be easily copied. There are, however, two disadvantages to Application Calling: • it can be difficult to implement because the applications must initially be altered using a special application • some applications may not be able to be altered properly The following paper is divided into two major parts. The first part presents ways to use Application Calling, and the second explains the technical points of setting it up

EE Student Workstation Lab Status Report December, 1988

The Maclab project in the Spring of 1988 demonstrated that providing a Macintosh workstation environment to some sections of EE 267 (Digital Logic Design Laboratory) was both useful and feasible on a small scale. The goals of the EE Student Workstation project this past Summer and Fall were: A. To provide all sections of EE 267 (approximately 200 students) with a Macintosh workstation environment for the simulation of digital logic circuits and for the preparation of reports. B. Tb provide a useful Macintosh workstation environment to other Electrical Engineering students. C. To transfer responsibility for operational aspects of the Macintosh Workstatiori facilities to the Engineering Computer Network (ECN). The opening of the new Materials Science and Electrical Engineering (MSEE) building in August 1988 provided space to establish the EE Student Workstation Laboratory; The facility occupies two rooms (186 and 190) within the terminal room complex of the MSEE building. The lab is equipped with 40 Macintosh Plus personal computers networked together via AppleTalk and bridged to the Engineering Computer Network (ECN). A Macintosh Il with two 40 Megabyte hard drives is used as an applications server. Application serving can also be handled by one of ECN\u27s Sun Server Machines. Using Aufs (Apple-Unix file serving) software, students can access and store Macintosh files on their regular ECN UNIX accounts. Each room is equipped with a dot matrix and a laser printer for hard copy output. An instructor\u27s machine is equipped with an LCD display and overhead projector so that large screen class demonstrations can be given. The goal of expanding use of MacIntosh student workstations to all EE267 students was successful. In addition, software purchases were made to make the facility a useful and productive environment for other EE students. Significant progress has been made in integrating this type of facility into normal ECN operations. This report describes the operation and status of the EE Student Workstation Labs as of the end of the 1988 Fall semester. Recommendations based upon the experience gained during the semester are made