Moving boundary and photoelastic coupling in GaAs optomechanical resonators

Chip-based cavity optomechanical systems are being considered for applications in sensing, metrology, and quantum information science. Critical to their development is an understanding of how the optical and mechanical modes interact, quantified by the coupling rate $g_{0}$. Here, we develop GaAs optomechanical resonators and investigate the moving dielectric boundary and photoelastic contributions to $g_{0}$. First, we consider coupling between the fundamental radial breathing mechanical mode and a 1550 nm band optical whispering gallery mode in microdisks. For decreasing disk radius from $R=5$ $\mu$m to $R=1$ $\mu$m, simulations and measurements show that $g_{0}$ changes from being dominated by the moving boundary contribution to having an equal photoelastic contribution. Next, we design and demonstrate nanobeam optomechanical crystals in which a $2.5$ GHz mechanical breathing mode couples to a 1550 nm optical mode predominantly through the photoelastic effect. We show a significant (30 $\%$) dependence of $g_{0}$ on the device's in-plane orientation, resulting from the difference in GaAs photoelastic coefficients along different crystalline axes, with fabricated devices exhibiting $g_{\text{0}}/2\pi$ as high as 1.1 MHz for orientation along the [110] axis. GaAs nanobeam optomechanical crystals are a promising system which can combine the demonstrated large optomechanical coupling strength with additional functionality, such as piezoelectric actuation and incorporation of optical gain media

An Application of Web 3.0: Positive WOM for Mobile Location-Based Apparel Shopping Services Usage

Web 3.0 is defined as the next paradigm shift of the Internet taking the best of web 2.0, including rich Internet applications and social media, and bringing them to mobile Internet devices and digital signage. Web 3.0 trends include a shift to outernet, location-based experiences, and the use of voice recognition in search applications (Buscemi & Marks, 2010). Mobile location-based services (LBS) offer shoppers reward opportunities when they physically visit stores or scan certain items

Growth, transport, and magnetic properties of Pr0.67Ca0.33MnO3 thin films

We have grown Pr0.67Ca0.33MnO3 thin films on LaAlO3 using pulsed laser deposition. Below 50 K, a field induced insulator-metal transition results in changes in resistivity of at least 6 orders of magnitude. The field induced conducting state is metastable at low temperature. The temperature dependence of the resistivity exhibits considerable hysteresis in a field of 40 kOe but becomes reversible in a field of 80 kOe

Stabilization of a Fabry-Perot interferometer using a suspension-point interferometer

A suspension-point interferometer (SPI) is an auxiliary interferometer for active vibration isolation, implemented at the suspension points of the mirrors of an interferometric gravitational wave detector. We constructed a prototype Fabry-Perot interferometer equipped with an SPI and observed vibration isolation in both the spectrum and transfer function. The noise spectrum of the main interferometer was reduced by 40 dB below 1 Hz. Transfer function measurements showed that the SPI also produced good vibration suppression above 1 Hz. These results indicate that SPI can improve both the sensitivity and the stability of the interferometer.Comment: 14 pages, 8 figures; added discussion; to be published in Physics Letters

Differential-difference system related to toroidal Lie algebra

We present a novel differential-difference system in (2+1)-dimensional space-time (one discrete, two continuum), arisen from the Bogoyavlensky's (2+1)-dimensional KdV hierarchy. Our method is based on the bilinear identity of the hierarchy, which is related to the vertex operator representation of the toroidal Lie algebra \sl_2^{tor}.Comment: 10 pages, 4 figures, pLaTeX2e, uses amsmath, amssymb, amsthm, graphic

Criminal Justice and Suicide Outcomes with Indiana's Risk-Based Gun Seizure Law

This article examines the application and effectiveness of a 2006 Indiana law designed to prevent gun violence by authorizing police officers to separate firearms from persons who present imminent or future risk of injury to self or others, or display a propensity for violent or emotionally unstable conduct. A court hearing is held to determine ongoing risk in these cases; a judge decides whether to return the seized firearms or retain them for up to five years. The study examines the frequency of criminal arrest as well as suicide outcomes for 395 gun-removal actions in Indiana. Fourteen individuals (3.5%) died from suicide, seven (1.8%) using a firearm. The study population's annualized suicide rate was about 31 times higher than that of the general adult population in Indiana, demonstrating that the law is being applied to a population genuinely at high risk. By extrapolating information on the case fatality rate for different methods of suicide, we calculated that one life was saved for every 10 gun-removal actions, similar to results of a previous study in Connecticut. Perspectives from key stakeholders are also presented along with implications for gun policy reform and implementation

Effect of Charge Fluctuations on the Persistent Current through a Quantum Dot

We study coherent charge transfer between an Aharonov-Bohm ring and a side-attached quantum dot. The charge fluctuation between the two sub-structures is shown to give rise to algebraic suppression of the persistent current circulating the ring as the size of the ring becomes relatively large. The charge fluctuation at resonance provides transition between the diamagnetic and the paramagnetic states. Universal scaling, crossover behavior of the persistent current from a continuous to a discrete energy limit in the ring is also discussed.Comment: 5 pages, 4 figure

Electronic and magnetic states in doped LaCoO_3

The electronic and magnetic states in doped perovskite cobaltites, (La, Sr)CoO_3, are studied in the numerically exact diagonalization method on Co_2O_{11} clusters. For realistic parameter values, it is shown that a high spin state and an intermediate spin state coexist in one-hole doped clusters due to strong p-d mixing. The magnetic states in the doped cobaltites obtained in the calculation explain various experimental results.Comment: 4 pages, 2 figures, epsfj.st

A chiral HPLC-MS/MS method for simultaneous quantification of warfarin enantiomers and its major hydroxylation metabolites of CYP2C9 and CYP3A4 in human plasma

Warfarin is an oral anticoagulant that requires frequent therapeutic drug monitoring due to a narrow therapeutic window, considerable interindividual variability in drug response, and susceptibility to drug-drug and drug-diet interactions. Enantiomeric separation and quantification of warfarin enantiomers and clinically important major hydroxylation metabolites are essential for drug interaction studies and phenotypic characterization of CYP2C9 and CYP3A4, the major Cytochrome P450 (CYP) enzymes involved in warfarin metabolism. Here, we describe the development and validation of a chiral high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)-based quantification of R-warfarin, S-warfarin, S-7-hydroxywarfarin (the major CYP2C9metabolite) and (9R; 10S)-10-hydroxywarfarin (the CYP3A4 metabolite) in human plasma. Simple protein precipitation-based extraction showed good recovery of analytes (82.9 - 96.9%). The developed method exhibited satisfactory intra-day and inter-day accuracy and precision. The lower limits of detection were 0.25nM (or ~0.08 ng/ml) for the warfarin enantiomers and 0.1nM (or ~0.04 ng/mL) for S-7-hydroxywarfarinand (9R; 10S)-10-hydroxywarfarin using only 50μL plasma during extraction. The validated method was successfully applied to analyze plasma samples obtained from a healthy human subject who enrolled in a clinical drug interaction study involving warfarin