Seeding of the nematic-isotropic phase transition by an electric field

In this paper, we use a relatively simple continuum model to investigate the effects of dielectric inhomogeneity within confined liquid crystal cells. Specifically, we consider, in planar, cylindrical and spherical geometries, the stability of a nematic-isotropic interface subject to an applied voltage. Depending on the magnitude of this voltage, the temperature and the geometry of the cell, the nematic region may shrink until the material is completely isotropic within the cell, grow until the nematic phase cells the cell or, in certain geometries, coexist with the isotropic phase. For planar geometry, no coexistence is found, but we are able to give analytical expressions for the critical voltage for an electric-field-induced phase transition as well as the critical wetting layer thickness for arbitrary applied voltage. In cells with cylindrical and spherical geometries, however, stable nematic-isotropic coexistence is predicted, the thickness of the nematic region being controllable by alteration of the applied voltage.</p

Alien Registration- Mottram, Hilda M. (Norway, Oxford County)

https://digitalmaine.com/alien_docs/21072/thumbnail.jp

ALMA CO J=6-5 observations of IRAS16293-2422: Shocks and entrainment

Observations of higher-excited transitions of abundant molecules such as CO are important for determining where energy in the form of shocks is fed back into the parental envelope of forming stars. The nearby prototypical and protobinary low-mass hot core, IRAS16293-2422 (I16293) is ideal for such a study. The source was targeted with ALMA for science verification purposes in band 9, which includes CO J=6-5 (E_up/k_B ~ 116 K), at an unprecedented spatial resolution (~0.2", 25 AU). I16293 itself is composed of two sources, A and B, with a projected distance of 5". CO J=6-5 emission is detected throughout the region, particularly in small, arcsecond-sized hotspots, where the outflow interacts with the envelope. The observations only recover a fraction of the emission in the line wings when compared to data from single-dish telescopes, with a higher fraction of emission recovered at higher velocities. The very high angular resolution of these new data reveal that a bow shock from source A coincides, in the plane of the sky, with the position of source B. Source B, on the other hand, does not show current outflow activity. In this region, outflow entrainment takes place over large spatial scales, >~ 100 AU, and in small discrete knots. This unique dataset shows that the combination of a high-temperature tracer (e.g., CO J=6-5) and very high angular resolution observations is crucial for interpreting the structure of the warm inner environment of low-mass protostars.Comment: Accepted for publication in A&A Letter

The RMS Survey: Resolving kinematic distance ambiguities towards a sample of compact HII regions using HI absorption

We present high-resolution HI data obtained using the Australia Telescope Compact Array to resolve the near/far distance ambiguities towards a sample of compact HII regions from the Red MSX Source (RMS) survey. The high resolution data are complemented with lower resolution archival HI data extracted from the Southern and VLA Galactic Plane surveys. We resolve the distance ambiguity for nearly all of the 105 sources where the continuum was strong enough to allow analysis of the HI absorption line structure. This represents another step in the determination of distances to the total RMS sample, which with over 1,000 massive young stellar objects and compact HII regions, is the largest and most complete sample of its kind. The full sample will allow the distribution of massive star formation in the Galaxy to be examined.Comment: Accepted by MNRAS. This paper consists of 15 pages and contains 10 figures and 5 table

A cluster of outflows in the Vulpecula Rift

We present $^{12}$CO, $^{13}$CO and C$^{18}$O (J=3$-$2) observations of a new cluster of outflows in the Vulpecula Rift with HARP-B on the JCMT. The mass associated with the outflows, measured using the $^{12}$CO HARP-B observations and assuming a distance to the region of 2.3 kpc, is 129 \msol{}, while the mass associated with the dense gas from C$^{18}$O observations is 458 \msol{} and the associated sub-millimeter core has a mass of 327 $\pm$ 112 \msol{} independently determined from Bolocam 1.1mm data. The outflow-to-core mass ratio is therefore $\sim$0.4, making this region one of the most efficient observed thus far with more than an order of magnitude more mass in the outflow than would be expected based on previous results. The kinetic energy associated with the flows, 94$\times10^{45}$ ergs, is enough to drive the turbulence in the local clump, and potentially unbind the local region altogether. The detection of SiO (J=8$-$7) emission toward the outflows indicates that the flow is still active, and not simply a fossil flow. We also model the SEDs of the four YSOs associated with the molecular material, finding them all to be of mid to early B spectral type. The energetic nature of the outflows and significant reservoir of cold dust detected in the sub-mm suggest that these intermediate mass YSOs will continue to accrete and become massive, rather than reach the main sequence at their current mass.Comment: 11 pages, 8 figures and 3 tables. Accepted to MNRAS. A higher-resolution version of figure 1 will be included in the published version and is available from the authors upon request. Updated with red and blue wings swapped to match doppler shif

Can grey ravens fly? Beyond Frayling's categories

This paper analyses the effect of Christopher Frayling's (1993) categorisation of artistic research ‘research into art and design, research through art and design and research for art and design’ on the debate surrounding the efficacy of studio-based artistic research as being valid within the university. James Elkins (2009:128) describes this as ‘the incommensurability of studio art production and university life’. Through an exploration of the positive and negative responses to Frayling this paper seeks to explore the influence that these initial definitions have come to have on framing the scope of the debate. The paper presents a range of responses and analyses them and focuses especially on the alternative frameworks that have been suggested and examines why they have so far not created a coherent and uncontested frame-work for practice-led research in the art and design field especially in relation to fine art

Derivative-order-dependent stability and transient behaviour in a predator–prey system of fractional differential equations

In this paper, the static and dynamic behaviour of a fractional-order predator–prey model are studied, where the nonlinear interactions between the two species lead to multiple stable states. As has been found in many previous systems, the stability of such states can be dependent on the fractional order of the time derivative, which is included as a phenomenological model of memory-effects in the predator and prey species. However, what is less well understood is the transient behaviour and dependence of the observed domains of attraction for each stable state on the order of the fractional time derivative. These dependencies are investigated using analytical (for the stability of equilibria) and numerical (for the observed domains of attraction) techniques. Results reveal far richer dynamics compared to the integer-order model. We conclude that, as well as the species and controllable parameters, the memory effect of the species will play a role in the observed behaviour of the system

Numerical evaluation of pin-bearing strength for the design of bolted connections of pultruded FRP material

This paper presents finite-element predictions for the strength of a pultruded fiber-reinforced polymer (FRP) material subjected to pin-bearing loading with hole clearance. One of the distinct modes of failure in steel bolted connections is bearing. It is caused by the compression action from the shaft pressing into the laminate, and when there is no lateral restraint the mechanism observed at maximum load shows brooming for delamination failure. Each lamina in the glass fiber polyester matrix material is modeled as a homogeneous, anisotropic continuum and a relatively very thin resin layer is assumed to contain any delamination cracking between stacked layers. A cohesive zone model is implemented to predict the size and location of the initial delamination, as well as the load-carrying capacity in a pin-bearing specimen. Finite-element simulations (as virtual tests) are performed at the mesoscale level to validate the modeling methodology against experimental strength test results with delamination failure, and to show how pin-bearing strength varies with parameter changes. For an example of the knowledge to be gained for the design of bolted connections, the parameteric study in which the mat reinforcement is either continuous strand or triaxial (+45°/90°/−45°/chopped+45°/90°/−45°/chopped strand) shows the latter does not provide an increase in pin-bearing strength