Using the local gyrokinetic code, GS2, to investigate global ITG modes in tokamaks. (I) s-α{\alpha} model with profile and flow shear effects

This paper combines results from a local gyrokinetic code with analytical theory to reconstruct the global eigenmode structure of the linearly unstable ion-temperature-gradient (ITG) mode with adiabatic electrons. The simulations presented here employ the s-${\alpha}$ tokamak equilibrium model. Local gyrokinetic calculations, using GS2 have been performed over a range of radial surfaces, x, and for ballooning phase angle, p, in the range -${\pi} {\leq} p {\leq\pi}$, to map out the complex local mode frequency, ${\Omega_0(x, p) = \omega_0(x, p) + i\gamma_0(x, p)}$. Assuming a quadratic radial profile for the drive, namely ${\eta_i = L_n/L_T}$, (holding constant all other equilibrium profiles such as safety factor, magnetic shear etc.), ${\Omega_0(x, p)}$ has a stationary point. The reconstructed global mode then sits on the outboard mid plane of the tokamak plasma, and is known as a conventional or isolated mode, with global growth rate, ${\gamma}$ ~ Max[${\gamma_0(x, p)}$], where ${\gamma_0(x, p)}$ is the local growth rate. Taking the radial variation in other equilibrium profiles (e.g safety factor q(x)) into account, removes the stationary point in ${\Omega_0(x, p)}$ and results in a mode that peaks slightly away from the outboard mid-plane with a reduced global growth rate. Finally, the influence of flow shear has also been investigated through a Doppler shift, ${\omega_0 \rightarrow \omega_0 + n\Omega^{\prime}x}$, where n is the toroidal mode number and ${\Omega^{\prime}}$ incorporates the effect of flow shear. The equilibrium profile variation introduces an asymmetry to the growth rate spectrum with respect to the sign of ${\Omega^{\prime}}$, consistent with recent global gyrokinetic calculations.Comment: 10 pages, 8 figures and 1 tabl

The First Study of Injury Epidemiology in Cheerleading during the 2016/2017 Season in the United Kingdom.

In 2016, competitive cheerleading was granted provisional recognition as an Olympic sport thus allowing it to be considered for future games inclusion. Team England including the ‘all girl elite’ and ‘co-ed elite’ won gold and silver respectively at the ICU World Cheerleading Championships. The aim of this study was to report the prevalence and incidence of injury in cheerleaders during the 2016/2017 UK season. Following ethical approval from the Leeds Beckett University research ethics committee, 182 competitive (3.7 ± 1.8 years’ experience) cheerleaders (173 female, mean (±SD): age 21 ± 4 y, height 165 ± 7 cm, weight 64.7 ± 13.9 kg) provided electronic informed consent. Players completed a retrospective injury history questionnaire adapted from a football consensus statement on injury reporting (Fuller et al., 2006, Scandinavian journal of medicine & science in sports, 16(2), 83-92). Severity of injury was categorised using a time loss definition: slight (1-3 days), minor (4-7 days), moderate (1-4 weeks) and major (4 weeks plus). On average, cheerleaders engaged in ~5 hours training per week and ~3.4 competitions during the season. The one season prevalence of injury in this sample was 73%. A total of 226 injuries were reported. First time injuries (69%) were more common than recurrent injuries (31%). The maximum number of injuries reported by a single cheerleader was 5. The overall (competition and training) incidence of injury was 4.9/1000h. The majority (86%) of injuries occurred during training (4.76/1000h). Injuries to the ankle (11.9%), face (11.5%) and low back (10.2%) were the most common. Ligaments were the most commonly injured tissues (22.9% of all injuries). The most commonly reported mechanism of injury was during a stunting manoeuvre (54.9% of all injuries). Minor injuries were most common (61%), followed by moderate (21%) and major injuries (18%). This is the first study to report the prevalence and incidence of injury in cheerleading. Unlike many sports, the majority of injuries occur during training rather than competition. We suggest that this is mainly down to differences in exposure. On average, competitions last for 2.5 minutes. It may also be that cheerleaders are more aggressive in their training practices in order to perfect routines for competition, which may indicate fewer mistakes leading to injury occur on the day of competition. Prospective studies are required to develop this area of research

Development of a theory of the spectral reflectance of minerals, part 2

Theory of diffuse reflectance of particulate media including garnet, glass, corundum powders, and mixture

The interplay of intrinsic excitability and network topology in spatiotemporal pattern generation in neural networks

http://deepblue.lib.umich.edu/bitstream/2027.42/109555/1/12868_2014_Article_3550.pd

Network topology and intrinsic excitability of the existing network drive integration patterns in a model of adult neurogenesis

http://deepblue.lib.umich.edu/bitstream/2027.42/112379/1/12868_2013_Article_3276.pd

Effect of Magnetization Inhomogeneity on Magnetic Microtraps for Atoms

We report on the origin of fragmentation of ultracold atoms observed on a permanent magnetic film atom chip. A novel technique is used to characterize small spatial variations of the magnetic field near the film surface using radio frequency spectroscopy of the trapped atoms. Direct observations indicate the fragmentation is due to a corrugation of the magnetic potential caused by long range inhomogeneity in the film magnetization. A model which takes into account two-dimensional variations of the film magnetization is consistent with the observations.Comment: 4 pages, 4 figure

Texture and shape of two-dimensional domains of nematic liquid crystal

We present a generalized approach to compute the shape and internal structure of two-dimensional nematic domains. By using conformal mappings, we are able to compute the director field for a given domain shape that we choose from a rich class, which includes drops with large and small aspect ratios, and sharp domain tips as well as smooth ones. Results are assembled in a phase diagram that for given domain size, surface tension, anchoring strength, and elastic constant shows the transitions from a homogeneous to a bipolar director field, from circular to elongated droplets, and from sharp to smooth domain tips. We find a previously unaccounted regime, where the drop is nearly circular, the director field bipolar and the tip rounded. We also find that bicircular director fields, with foci that lie outside the domain, provide a remarkably accurate description of the optimal director field for a large range of values of the various shape parameters.Comment: 12 pages, 10 figure