Homogeneous alignment of nematic liquid crystals by ion beam etched surfaces

A wide range of ion beam etch parameters capable of producing uniform homogeneous alignment of nematic liquid crystals on SiO2 films are discussed. The alignment surfaces were generated by obliquely incident (angles of 5 to 25 deg) argon ions with energies in the range of 0.5 to 2.0 KeV, ion current densities of 0.1 to 0.6 mA sq cm and etch times of 1 to 9 min. A smaller range of ion beam parameters (2.0 KeV, 0.2 mA sq cm, 5 to 10 deg and 1 to 5 min.) were also investigated with ZrO2 films and found suitable for homogeneous alignment. Extinction ratios were very high (1000), twist angles were small ( or = 3 deg) and tilt-bias angles very small ( or = 1 deg). Preliminary scanning electron microscopy results indicate a parallel oriented surface structure on the ion beam etched surfaces which may determine alignment

Ultrafast dynamics in the presence of antiferromagnetic correlations in electron-doped cuprate La2−x_{2-x}Cex_xCuO4±δ_{4\pm\delta}

We used femtosecond optical pump-probe spectroscopy to study the photoinduced change in reflectivity of thin films of the electron-doped cuprate La$_{2-x}$Ce$_x$CuO$_4$ (LCCO) with dopings of x$=$0.08 (underdoped) and x$=$0.11 (optimally doped). Above T$_c$, we observe fluence-dependent relaxation rates which onset at a similar temperature that transport measurements first see signatures of antiferromagnetic correlations. Upon suppressing superconductivity with a magnetic field, it is found that the fluence and temperature dependence of relaxation rates is consistent with bimolecular recombination of electrons and holes across a gap (2$\Delta_{AF}$) originating from antiferromagnetic correlations which comprise the pseudogap in electron-doped cuprates. This can be used to learn about coupling between electrons and high-energy ($\omega>2\Delta_{AF}$) excitations in these compounds and set limits on the timescales on which antiferromagnetic correlations are static

Robust localization methods for passivity enforcement of linear macromodels

In this paper we solve a non-smooth convex formulation for passivity enforcement of linear macromodels using robust localization based algorithms such as the ellipsoid and the cutting plane methods. Differently from existing perturbation based techniques, we solve the formulation based on the direct ℌ∞ norm minimization through perturbation of state-space model parameters. We provide a systematic way of defining an initial set which is guaranteed to contain the global optimum. We also provide a lower bound on the global minimum, that grows tighter at each iteration and hence guarantees δ - optimality of the computed solution. We demonstrate the robustness of our implementation by generating accurate passive models for challenging examples for which existing algorithms either failed or exhibited extremely slow convergenc

Probing the band structure of quadri-layer graphene with magneto-phonon resonance

We show how the magneto-phonon resonance, particularly pronounced in sp2 carbon allotropes, can be used as a tool to probe the band structure of multilayer graphene specimens. Even when electronic excitations cannot be directly observed, their coupling to the E2g phonon leads to pronounced oscillations of the phonon feature observed through Raman scattering experiments with multiple periods and amplitudes detemined by the electronic excitation spectrum. Such experiment and analysis have been performed up to 28T on an exfoliated 4-layer graphene specimen deposited on SiO2, and the observed oscillations correspond to the specific AB stacked 4-layer graphene electronic excitation spectrum.Comment: 11 pages, 5 Fi

Feel My Pain: Design and Evaluation of Painpad, a Tangible Device for Supporting Inpatient Self-Logging of Pain

Monitoring patients' pain is a critical issue for clinical caregivers, particularly among staff responsible for providing analgesic relief. However, collecting regularly scheduled pain readings from patients can be difficult and time-consuming for clinicians. In this paper we present Painpad, a tangible device that was developed to allow patients to engage in self-logging of their pain. We report findings from two hospital-based field studies in which Painpad was deployed to a total of 78 inpatients recovering from ambulatory surgery. We find that Painpad results in improved frequency and compliance with pain logging, and that self-logged scores may be more faithful to patients' experienced pain than corresponding scores reported to nurses. We also show that older adults may prefer tangible interfaces over tablet-based alternatives for reporting their pain, and we contribute design lessons for pain logging devices intended for use in hospital settings

Quantification of temporal fault trees based on fuzzy set theory

© Springer International Publishing Switzerland 2014. Fault tree analysis (FTA) has been modified in different ways to make it capable of performing quantitative and qualitative safety analysis with temporal gates, thereby overcoming its limitation in capturing sequential failure behaviour. However, for many systems, it is often very difficult to have exact failure rates of components due to increased complexity of systems, scarcity of necessary statistical data etc. To overcome this problem, this paper presents a methodology based on fuzzy set theory to quantify temporal fault trees. This makes the imprecision in available failure data more explicit and helps to obtain a range of most probable values for the top event probability

Factors affecting the accumulation of 9-methoxycanthin-6-one in callus cultures of Eurycoma longifolia.

A study was conducted to improve 9-methoxycanthin-6-one productivity (potential anti-tumour compound) from callus cultures of Eurycoma longifolia (Tongkat Ali). Several factors affecting 9-methoxycanthin-6-one production in callus cultures such as different medium compositions and physical factors were investigated and analyzed. Results show that a higher production of 9-methoxycanthin-6-one (3.84 mg'g-1 DW (Dry Weight)) is obtained from callus cultured in ¼ MS basal media. At fructose of 2% (w/v), the production of 9-methoxycanthin-6-one (4.59 mg'g-1 DW) is promoted to gain the highest yield, compared to other carbon sources tested. The addition of 2.0-mg'L-1 dicamba also increases 9-methoxycanthin-6-one production (12.3 mg'g-1 DW). Higher production of 9-methoxycanthin-6-one was obtained at pH 5.5 (1.53 mg'g-1 DW). Production of 9-methoxycanthin-6-one (2.34 mg'g-1 DW) in callus cultures is also increased when the medium is added with 1×10-1 μM phenylalanine. This study suggests that the successful production of 9-methoxycanthin-6-one in vitro cultures has a potential in large-scale production using bioreactor technology