Microgravimetric immunosensor for direct detection of aerosolized influenza A virus particles.

The development and characterization of a quartz crystal microbalance (QCM) sensor for the direct detection of aerosolized influenza A virions is reported. Self-assembled monolayers (SAMs) of mercaptoundecanoic acid (MUA) are formed on QCM gold electrodes to provide a surface amenable for the immobilization of anti-influenza A antibodies using NHS/EDC coupling chemistry. The surface-bound antibody provides a selective and specific sensing interface for the capture of influenza virions. A nebulizer is used to create aerosolized samples and is directly connected to a chamber housing the antibody-modified crystal ("immunochip"). Upon exposure to the aerosolized virus, the interaction between the antibody and virus leads to a dampening of the oscillation frequency of the quartz crystal. The magnitude of frequency change is directly related to virus concentration. Control experiments using aerosols from chicken egg allantoic fluid and an anti-murine antibody based immunosensor confirm that the observed signal originates from specific viral binding on the chip surface. Step-by-step surface modification of MUA assembly, antibody attachment, and antibody-virus interaction are characterized by atomic force microscopy (AFM) imaging analysis. Using the S/N = 3 principle, the limit of detection is estimated to be 4 virus particles/mL. The high sensitivity and real-time sensing scheme presented here can play an important role in the public health arena by offering a new analytical tool for identifying bio-contaminated areas and assisting in timely patient diagnosis

Site selective reading of epigenetic markers by a dual-mode synthetic receptor array.

Variably functionalized self-folding deep cavitands form an arrayed, fluorescent indicator displacement assay system for the detection of post-translationally modified (PTM) histone peptides. The hosts bind trimethyllysine (KMe3) groups, and use secondary upper rim interactions to provide more sensitive discrimination between targets with identical KMe3 binding handles. The sensor array uses multiple different recognition modes to distinguish between miniscule differences in target, such as identical lysine modifications at different sites of histone peptides. In addition, the sensor is affected by global changes in structure, so it is capable of discriminating between identical PTMs, at identical positions on amino acid fragments that vary only in peptide backbone length, and can be applied to detect non-methylation modifications such as acetylation and phosphorylations located multiple residues away from the targeted binding site. The synergistic application of multiple variables allows dual-mode deep cavitands to approach levels of recognition selectivity usually only seen with antibodies

2002. Using two-photon standing waves and patterned photobleaching to measure diffusion from nanometers to microns in biological systems

A method of measuring molecular diffusion rates in microscopic sample volumes is described. This method utilizes the standing wave interference created by colliding two counterpropagating laser beams at the focus of two opposing microscope objectives, creating a periodic light distribution in a volume on the order of 1 fl. By using a Pockels cell to vary the laser intensity with a time resolution of milliseconds, we show how this experimental geometry can be used to perform ultrahigh resolution fluorescence recovery after patterned photobleaching ͑FRAPP͒ experiments. A mathematical treatment of the experiment shows that the laser excitation profile has two characteristic length scales, the width of the focal spot and the period of the standing wave, which permits the simultaneous measurement of dynamics on two separate length scales. This feature may be used to determine whether the measured diffusion is anomalous. We present experimental results using a femtosecond Ti:sapphire laser to create a two-photon excitation profile with a fringe visibility on the order of 100. This standing wave is used to demonstrate FRAPP in both model dye/polymer systems and in more complex systems like living cells stained with a fluorescent dye. By combining the advantages of standing wave microscopy and two-photon fluorescence recovery after photobleaching, this technique permits the measurement of very short length motions in localized sample volumes, which should be useful in both biology and the study of diffusion in microscopically heterogeneous systems

Mechanics of Rotating Isolated Horizons

Black hole mechanics was recently extended by replacing the more commonly used event horizons in stationary space-times with isolated horizons in more general space-times (which may admit radiation arbitrarily close to black holes). However, so far the detailed analysis has been restricted to non-rotating black holes (although it incorporated arbitrary distortion, as well as electromagnetic, Yang-Mills and dilatonic charges). We now fill this gap by first introducing the notion of isolated horizon angular momentum and then extending the first law to the rotating case.Comment: 31 pages REVTeX, 1 eps figure; Minor typos corrected and a footnote adde

Incorporating interactive 3-dimensional graphics in astronomy research papers

Most research data collections created or used by astronomers are intrinsically multi-dimensional. In contrast, all visual representations of data presented within research papers are exclusively 2-dimensional. We present a resolution of this dichotomy that uses a novel technique for embedding 3-dimensional (3-d) visualisations of astronomy data sets in electronic-format research papers. Our technique uses the latest Adobe Portable Document Format extensions together with a new version of the S2PLOT programming library. The 3-d models can be easily rotated and explored by the reader and, in some cases, modified. We demonstrate example applications of this technique including: 3-d figures exhibiting subtle structure in redshift catalogues, colour-magnitude diagrams and halo merger trees; 3-d isosurface and volume renderings of cosmological simulations; and 3-d models of instructional diagrams and instrument designs.Comment: 18 pages, 7 figures, submitted to New Astronomy. For paper with 3-dimensional embedded figures, see http://astronomy.swin.edu.au/s2plot/3dpd

Fractal Theory Space: Spacetime of Noninteger Dimensionality

We construct matter field theories in ``theory space'' that are fractal, and invariant under geometrical renormalization group (RG) transformations. We treat in detail complex scalars, and discuss issues related to fermions, chirality, and Yang-Mills gauge fields. In the continuum limit these models describe physics in a noninteger spatial dimension which appears above a RG invariant ``compactification scale,'' M. The energy distribution of KK modes above M is controlled by an exponent in a scaling relation of the vacuum energy (Coleman-Weinberg potential), and corresponds to the dimensionality. For truncated-s-simplex lattices with coordination number s the spacetime dimensionality is 1+(3+2ln(s)/ln(s+2)). The computations in theory space involve subtleties, owing to the 1+3 kinetic terms, yet the resulting dimensionalites are equivalent to thermal spin systems. Physical implications are discussed.Comment: 28 pages, 6 figures; Paper has been amplified with a more detailed discussion of a number of technical issue

Assessment of the revised Difficulties in Emotion Regulation Scales among adolescents and adults with severe mental illness

The Difficulties in Emotion Regulation Scale (DERS) comprising 36 items has been widely used across age, gender, psychopathology, language, and culture. Recently several alternative abridged forms have been introduced, namely, the DERS-16 (Bjureberg et al. 2016), the DERS-SF (Kaufman et al. 2016), and the DERS-18 (Victor and Klonsky, 2016), each composed of 16 or 18 items, to provide researchers and clinicians with a shorter measure of emotion dysregulation. However, no study to date has directly compared the psychometrics of these alternative forms. In the present study, using confirmatory factor analysis we first examined the factor structure of the four models of the DERS in two inpatient samples of 636 adolescents in the age-range of 12–17 years (M = 15.33, SD = 1.43), and 1807 adults in the age-range of 18–76 years (M = 34.86, SD = 14.63) with severe mental illness. Next, measurement invariance was tested comparing the two age groups across the four models of DERS. Only the DERS-SF established metric and scalar measurement invariance. Findings suggest that the factor structure of the original and the abridged models of DERS have acceptable fit, however only DERS-SF had equivalence of factor loadings and item intercepts across adolescents and adults

Broken discs: warp propagation in accretion discs

We simulate the viscous evolution of an accretion disc around a spinning black hole. In general any such disc is misaligned, and warped by the Lense-Thirring effect. Unlike previous studies we use effective viscosities constrained to be consistent with the internal fluid dynamics of the disc. We find that nonlinear fluid effects, which reduce the effective viscosities in warped regions, can promote the breaking of the disc into two distinct planes. This occurs when the Shakura & Sunyaev dimensionless viscosity parameter alpha is ~ 45 degrees. The break can be a long-lived feature, propagating outwards in the disc on the usual alignment timescale, after which the disc is fully co- or counter-aligned with the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the inner disc, and so any jets, may be noticeably misaligned with respect to the orbital plane.Comment: 8 pages, 9 figures. Accepted for publication in MNRA

The Shape of an Accretion Disc in a Misaligned Black Hole Binary

We model the overall shape of an accretion disc in a semi-detached binary system in which mass is transfered on to a spinning black hole the spin axis of which is misaligned with the orbital rotation axis. We assume the disc is in a steady state. Its outer regions are subject to differential precession caused by tidal torques of the companion star. These tend to align the outer parts of the disc with the orbital plane. Its inner regions are subject to differential precession caused by the Lense-Thirring effect. These tend to align the inner parts of the disc with the spin of the black hole. We give full numerical solutions for the shape of the disc for some particular disc parameters. We then show how an analytic approximation to these solutions can be obtained for the case when the disc surface density varies as a power law with radius. These analytic solutions for the shape of the disc are reasonably accurate even for large misalignments and can be simply applied for general disc parameters. They are particularly useful when the numerical solutions would be slow.Comment: Accepted for publication in MNRA