Time-resolved optical/near-IR polarimetry of V404 Cyg during its 2015 outburst

We present optical and near-IR linear polarimetry of V404 Cyg during its 2015 outburst and in quiescence. We obtained time resolved r'-band polarimetry when the source was in outburst, near-IR polarimetry when the source was near quiescence and multiple wave-band optical polarimetry later in quiescence. The optical to near-IR linear polarization spectrum can be described by interstellar dust and an intrinsic variable component. The intrinsic optical polarization, detected during the rise of one of the brightest flares of the outburst, is variable, peaking at 4.5 per cent and decaying to 3.5 per cent. We present several arguments that favour a synchrotron jet origin to this variable polarization, with the optical emission originating close to the jet base. The polarization flare occurs during the initial rise of a major radio flare event that peaks later, and is consistent with a classically evolving synchrotron flare from an ejection event. We conclude that the optical polarization flare represents a jet launching event; the birth of a major ejection. For this event we measure a rather stable polarization position angle of -9 degrees E of N, implying that the magnetic field near the base of the jet is approximately perpendicular to the jet axis. This may be due to the compression of magnetic field lines in shocks in the accelerated plasma, resulting in a partially ordered transverse field that have now been seen during the 2015 outburst. We also find that this ejection occurred at a similar stage in the repetitive cycles of flares.Comment: 9 pages, 5 figures, accepted for publication by MNRA

Appearance concerns in later life: Do they really exist?

In Western society, where youth and beauty are given high status, older people can often feel pressured to adopt appearance-enhancing strategies, such as using anti-ageing products. Those who invest time and money into their image often do so to show they are coping well with later life and gain respect from others. Claire Hamlet examines the concept of successful ageing in relation to appearanc

Past, Present, and Future Fishery Management in Cabinet Gorge and Noxon Rapids Reservoirs

Noxon Rapids and Cabinet Gorge Reservoirs are run-of-the-river hydroelectric impoundments on the Clark Fork River in western Montana. Operations at Noxon Rapids Reservoir changed in 1961 and 1978. The first change in operations increased average annual spring drawdown from less than 10 to more than 30 feet. The second eliminated drawdowns of more than 6 feet, except for unusual power demands. Establishment and maintenance of a satisfactory sport fishery has been largely unsuccessful in both reservoirs since the 1950\u27s. Rainbow trout (Salmo gairdneri) exhibited potential from 1958 through 1960 when they produced an excellent fishery, followed by a dramatic decline in 1961. Continued planting of rainbow trout never reestablished a substantial fishery. Other fish species planted produced similar results with the exception of brown trout (Salmo trutta) and small mouth bass (Micropterus dolomieui), which presently provide a modest fishery. Largemouth bass (Micropterus salmoides) were present prior to impoundment and appear to be increasing. Operation changes, combined with the brief retention times, have encouraged the downstream movement of most introduced salmonids in Noxon Rapids and Cabinet Gorge Reservoirs

Turbulence Model Implementation and Verification in the SENSEI CFD Code

This paper outlines the implementation and verification of the negative Spalart-Allmaras turbulence model into the SENSEI CFD code. The SA-neg turbulence model is implemented in a flexible, object-oriented framework where additional turbulence models can be easily added. In addition to outlining the new turbulence modeling framework in SENSEI, an overview of the other general improvements to SENSEI is provided. The results for four 2D test cases are compared to results from CFL3D and FUN3D to verify that the turbulence models are implemented properly. Several differences in the results from SENSEI, CFL3D, and FUN3D are identified and are attributed to differences in the implementation and discretization order of the boundary conditions as well as the order of discretization of the turbulence model. When a solid surface is located near or intersects an inflow or outflow boundary, higher order boundary conditions should be used to limit their effect on the forces on the surface. When the turbulence equations are discretized using second order spatial accuracy, the edge of the eddy viscosity profile seems to be sharper than when a first order discretization is used. However, the discretization order of the turbulence equation does not have a significant impact on output quantities of interest, such as pressure and viscous drag, for the cases studied

Pre-operative experiences and post-operative benefits of ptosis surgery: A qualitative study

© 2017 Taylor & Francis. This qualitative study sought to explore the experiences of patients who had undergone successful ptosis correction surgery. Participants were recruited from Bristol Eye Hospital. Nine participants were interviewed using a semi-structured interview schedule and open ended questions. Data were analysed using inductive thematic analysis. Four major themes were identified from patient accounts. Patients described the psychosocial and functional difficulties they experienced living with ptosis, and the subsequent benefits of surgery. Patients reported experiencing appearance related anxiety pre-operatively due to their condition and engaging in behaviours to avoid social encounters. Gender differences were noted in the internalization of perceived negative reactions from others, with men describing fewer adverse impacts. Patients described perceived barriers to seeking surgery including a lack of awareness of ptosis as a treatable condition, the perception that being concerned with their appearance could be seen as vain and the view that ptosis surgery is synonymous with cosmetic surgery. Following successful surgery patients outlined positive impacts on their vision, appearance and psychosocial well-being after successful surgery. This qualitative study highlights the complexities of the factors and processes contributing to the psychosocial impacts of ptosis and the potential benefits of surgery and/or psychosocial support. An increased awareness amongst people with ptosis of the potential positive impacts of surgery and an enhanced understanding of the reasons why patients may not seek treatment amongst health care professionals are likely to benefit this often overlooked patient group

Aspects of Numerical Simulation of Circulation Control Airfoils

The mass-averaged compressible Navier-Stokes equations are solved for circulation control airfoils. Numerical solutions are computed with a multigrid method that uses an implicit approximate factorization smoother. The effects of flow conditions (e.g., free-stream Mach number, angle of attack, momentum coefficient) and mesh on the prediction of circulation control airfoil flows are considered. In addition, the impact of turbulence modeling, including curvature effects and modifications to reduce eddy viscosity levels in the wall jet (i.e., Coanda flow), is discussed. Computed pressure distributions are compared with available experimental data

A close-pair binary in a distant triple supermassive black-hole system

Galaxies are believed to evolve through merging, which should lead to multiple supermassive black holes in some. There are four known triple black hole systems, with the closest pair being 2.4 kiloparsecs apart (the third component is more distant at 3 kiloparsecs), which is far from the gravitational sphere of influence of a black hole with mass $\sim$10$^9$ M$_\odot$ (about 100 parsecs). Previous searches for compact black hole systems concluded that they were rare, with the tightest binary system having a separation of 7 parsecs. Here we report observations of a triple black hole system at redshift z=0.39, with the closest pair separated by $\sim$140 parsecs. The presence of the tight pair is imprinted onto the properties of the large-scale radio jets, as a rotationally-symmetric helical modulation, which provides a useful way to search for other tight pairs without needing extremely high resolution observations. As we found this tight pair after searching only six galaxies, we conclude that tight pairs are more common than hitherto believed, which is an important observational constraint for low-frequency gravitational wave experiments.Comment: 21 pages, 6 figures. Published online by Nature on 25 June 2014. Extremely minor differences with published version exis

Verification and Validation of the k-kL Turbulence Model in FUN3D and CFL3D Codes

The implementation of the k-kL turbulence model using multiple computational uid dy- namics (CFD) codes is reported herein. The k-kL model is a two-equation turbulence model based on Abdol-Hamid's closure and Menter's modi cation to Rotta's two-equation model. Rotta shows that a reliable transport equation can be formed from the turbulent length scale L, and the turbulent kinetic energy k. Rotta's equation is well suited for term-by-term mod- eling and displays useful features compared to other two-equation models. An important di erence is that this formulation leads to the inclusion of higher-order velocity derivatives in the source terms of the scale equations. This can enhance the ability of the Reynolds- averaged Navier-Stokes (RANS) solvers to simulate unsteady ows. The present report documents the formulation of the model as implemented in the CFD codes Fun3D and CFL3D. Methodology, veri cation and validation examples are shown. Attached and sepa- rated ow cases are documented and compared with experimental data. The results show generally very good comparisons with canonical and experimental data, as well as matching results code-to-code. The results from this formulation are similar or better than results using the SST turbulence model

Computation of Sound Generated by Viscous Flow Over a Circular Cylinder

The Lighthill acoustic analogy approach combined with Reynolds-averaged Navier Stokes is used to predict the sound generated by unsteady viscous flow past a circular cylinder assuming a correlation length of 10 cylinder diameters. The two-dimensional unsteady flow field is computed using two Navier-Stokes codes at a low Mach number over a range of Reynolds numbers from 100 to 5 million. Both laminar flow as well as turbulent flow with a variety of eddy viscosity turbulence models are employed. Mean drag and Strouhal number are examined, and trends similar to experiments are observed. Computing the noise within the Reynolds number regime where transition to turbulence occurs near the separation point is problematic: laminar flow exhibits chaotic behavior and turbulent flow exhibits strong dependence on the turbulence model employed. Comparisons of far-field noise with experiment at a Reynolds number of 90,000, therefore, vary significantly, depending on the turbulence model. At a high Reynolds number outside this regime, three different turbulence models yield self-consistent results

Culture clash: Appearance concerns in black and minority ethnic groups

Around the world, men and women of all cultures and ethnicities are being exposed to Western appearance ideals. Paired with a lack of representation of black and minority ethnic (BME) men and women in the mainstream media, the public's appreciation of ethnic diversity is being threatened. Nicola Stock examines the growing trend of appearance-altering practice among those from BME communities