New fabrication techniques for high quality photonic crystals

We have developed new methods for the fabrication of high quality two-dimensional (2D) and three-dimensional (3D) photonic crystals. These techniques involve anisotropic etching and steam oxidation of AlAs mask layers. We have made manufacturable 2D photonic crystals with high aspect ratios for use as micropolarizers and have measured extinction ratios larger than 800 to 1 between TE and TM modes transmitted through these structures. The new Al2O3 mask fabrication technique also allows us to fabricate 3D structures with up to six repeating layers in depth and over 90% attenuation in the band gap region. Here, we show the fabrication details and performance of 2D and 3D photonic crystals

Topological Quantum Computing with p-Wave Superfluid Vortices

It is shown that Majorana fermions trapped in three vortices in a p-wave superfluid form a qubit in a topological quantum computing (TQC). Several similar ideas have already been proposed: Ivanov [Phys. Rev. Lett. {\bf 86}, 268 (2001)] and Zhang {\it et al.} [Phys. Rev. Lett. {\bf 99}, 220502 (2007)] have proposed schemes in which a qubit is implemented with two and four Majorana fermions, respectively, where a qubit operation is performed by exchanging the positions of Majorana fermions. The set of gates thus obtained is a discrete subset of the relevant unitary group. We propose, in this paper, a new scheme, where three Majorana fermions form a qubit. We show that continuous 1-qubit gate operations are possible by exchanging the positions of Majorana fermions complemented with dynamical phase change. 2-qubit gates are realized through the use of the coupling between Majorana fermions of different qubits.Comment: 5 pages, 2 figures. Two-qubit gate implementation is added

Stokes tomography of radio pulsar magnetospheres. II. Millisecond pulsars

The radio polarization characteristics of millisecond pulsars (MSPs) differ significantly from those of non-recycled pulsars. In particular, the position angle (PA) swings of many MSPs deviate from the S-shape predicted by the rotating vector model, even after relativistic aberration is accounted for, indicating that they have non-dipolar magnetic geometries, likely due to a history of accretion. Stokes tomography uses phase portraits of the Stokes parameters as a diagnostic tool to infer a pulsar's magnetic geometry and orientation. This paper applies Stokes tomography to MSPs, generalizing the technique to handle interpulse emission. We present an atlas of look-up tables for the Stokes phase portraits and PA swings of MSPs with current-modified dipole fields, filled core and hollow cone beams, and two empirical linear polarization models. We compare our look-up tables to data from 15 MSPs and find that the Stokes phase portraits for a current-modified dipole approximately match several MSPs whose PA swings are flat or irregular and cannot be reconciled with the standard axisymmetric rotating vector model. PSR J1939+2134 and PSR J0437$-$4715 are modelled in detail. The data from PSR J1939+2134 at 0.61\,GHz can be fitted well with a current-modified dipole at $(\alpha, i) = (22 \pm 2^\circ, 80 \pm 1^\circ)$ and emission altitude 0.4 $r_\text{LC}$. The fit is less accurate for PSR J1939+2134 at 1.414\,GHz, and for PSR J0437$-$4715 at 1.44\,GHz, indicating that these objects may have a more complicated magnetic field geometry, such as a localized surface anomaly or a polar magnetic mountain.Comment: 38 pages, 33 figures, accepted for publication by MNRA

Finite Element Modeling of Small-Scale Tapered Wood-Laminated Composite Poles with Biomimicry Features1

Tapered composite poles with biomimicry features as in bamboo are a new generation of wood laminated composite poles that may some day be considered as an alternative to solid wood poles that are widely used in the transmission and telecommunication fields. Five finite element models were developed with ANSYS to predict and assess the performance of five types of composites members: a tapered hollow pole with webs (Pole-A), a tapered hollow pole without webs (Pole-B), a tapered solid composite pole (Pole-C), a uniform-diameter hollow pole with webs (Pole-D), and a uniform-diameter hollow pole without webs (Pole-E). The predicted deflection by these models agreed well with those of the experiment, and the predicted normal stress agreed with those calculated. The normal and shear stress distributions inside the members were investigated, and stress distributions in the XY and YZ planes are exhibited. As expected, the webs reduced the local shear stress and improved shear capacity, especially in the top and groundline regions where shear levels were the highest. The webs had little effect on the normal stress. Shear stress increased from the bottom to the top for the members with taper. Large shear stress concentration was predicted in a small region close to the groundlines. The models also predicted that the shear stress of the tapered hollow poles would decrease from the inside to the outside surfaces in XY plane

Nagy-Soper subtraction scheme for multiparton final states

In this work, we present the extension of an alternative subtraction scheme for next-to-leading order QCD calculations to the case of an arbitrary number of massless final-state partons. The scheme is based on the splitting kernels of an improved parton shower and comes with a reduced number of final state momentum mappings. While a previous publication including the setup of the scheme has been restricted to cases with maximally two massless partons in the final state, we here provide the final state real emission and integrated subtraction terms for processes with any number of massless partons. We apply our scheme to three jet production at lepton colliders at next-to-leading order and present results for the differential C parameter distribution.Comment: 45 pages, 5 figures v2: several references added; v3: title changed, references and a discussion of further scaling improvement added. Corresponds to published journal versio

Intra- and Inter-Individual Variance of Gene Expression in Clinical Studies

BACKGROUND: Variance in microarray studies has been widely discussed as a critical topic on the identification of differentially expressed genes; however, few studies have addressed the influence of estimating variance. METHODOLOGY/PRINCIPAL FINDINGS: To break intra- and inter-individual variance in clinical studies down to three levels--technical, anatomic, and individual--we designed experiments and algorithms to investigate three forms of variances. As a case study, a group of "inter-individual variable genes" were identified to exemplify the influence of underestimated variance on the statistical and biological aspects in identification of differentially expressed genes. Our results showed that inadequate estimation of variance inevitably led to the inclusion of non-statistically significant genes into those listed as significant, thereby interfering with the correct prediction of biological functions. Applying a higher cutoff value of fold changes in the selection of significant genes reduces/eliminates the effects of underestimated variance. CONCLUSIONS/SIGNIFICANCE: Our data demonstrated that correct variance evaluation is critical in selecting significant genes. If the degree of variance is underestimated, "noisy" genes are falsely identified as differentially expressed genes. These genes are the noise associated with biological interpretation, reducing the biological significance of the gene set. Our results also indicate that applying a higher number of fold change as the selection criteria reduces/eliminates the differences between distinct estimations of variance

Absorption cross sections of HCl and DCl at 135-232 nanometers: implications for photodissociation on Venus

Cross sections for photoabsorption of HCl and DCl are determined in the spectral region of 135-232 nm using radiation from a synchrotron light source. At wavelengths near the onset of absorption (λ > 200 nm), cross sections of HCl are approximately 5-10 times larger than those of DCl. These data are used to calculate rates of photodissociation of HCl and DCl in the Venusian atmosphere. For the entire wavelength region measured, the rate of photodissociation of DCl is only 16% that of HCl. The difference in rates of photodissociation contributes to the exceptionally large [D]/[H] ratio of the Venusian atmosphere

On the air pollutant removal mechanism from 2D urban street canyons

postprintThe 2011 General Assembly of the European Geosciences Union (EGU), Vienna, Austria, 3-8 April 2011. In Geophysical Research Abstracts, 2011, v. 13, EGU2011-171

Synthesis of hexahydrofuro[3,2-c]quinoline, a martinelline type analogue and investigation of its biological activity

2015-2016 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe