The behavioural time budget of 140 turkey poults housed on litter in groups of 10-11 in small pens was recorded by individual scan sampling from 1-day-old to 12-weeks-old. Over this time period some behaviour (sitting/sleeping) remained relatively constant, some (feeding) declined and remained low, some (standing/walking, drinking) declined and rose again, while some (environmental pecking, bird pecking, preening) rose and then declined. By 12 weeks the incidence of some behaviours appeared to have stabilized, though others were still changing. A substantial proportion of their activity could be categorized as beak-related behaviour. Feather pecking and cannibalism are major behavioural and welfare problems in intensively-housed turkeys; it is postulated that one reason for this may be because a major proportion of their beak-related behaviour is strongly directed towards plumage, either their own or that of other birds, rather than towards food or environmental stimuli. One possible solution may be to seek ways of increasing the proportion of time they spend feeding.

Over the last 25 years, radiowave detection of neutrino-generated signals, using cold polar ice as the neutrino target, has emerged as perhaps the most promising technique for detection of extragalactic ultra-high energy neutrinos (corresponding to neutrino energies in excess of 0.01 Joules, or 1017 electron volts). During the summer of 2021 and in tandem with the initial deployment of the Radio Neutrino Observatory in Greenland (RNO-G), we conducted radioglaciological measurements at Summit Station, Greenland to refine our understanding of the ice target. We report the result of one such measurement, the radio-frequency electric field attenuation length $L_\alpha$. We find an approximately linear dependence of $L_\alpha$ on frequency with the best fit of the average field attenuation for the upper 1500 m of ice: $\langle L_\alpha \rangle = ( ( 1154 \pm 121) - ( 0.81 \pm 0.14) \, ( \nu /{\rm MHz}) ) \,{\rm m}$ for frequencies ν ∈ [145 − 350] MHz.

The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ($B_0 = 12.2$ T), compact ($R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in a compact device. The goal of $Q>2$ is achievable with conservative physics assumptions ($H_{98,y2} = 0.7$) and, with the nominal assumption of $H_{98,y2} = 1$, SPARC is projected to attain $Q \approx 11$ and $P_{\textrm {fusion}} \approx 140$ MW. SPARC will therefore constitute a unique platform for burning plasma physics research with high density ($\langle n_{e} \rangle \approx 3 \times 10^{20}\ \textrm {m}^{-3}$), high temperature ($\langle T_e \rangle \approx 7$ keV) and high power density ($P_{\textrm {fusion}}/V_{\textrm {plasma}} \approx 7\ \textrm {MW}\,\textrm {m}^{-3}$) relevant to fusion power plants. SPARC's place in the path to commercial fusion energy, its parameters and the current status of SPARC design work are presented. This work also describes the basis for global performance projections and summarizes some of the physics analysis that is presented in greater detail in the companion articles of this collection.

Objectives: Essential tremor (ET) is a movement disorder characterized by action tremor which impacts motor execution. Given the disrupted cerebellar-thalamo-cortical networks in ET, we hypothesized that ET could interfere with the control mechanisms involved in regulating motor performance. The ability to inhibit or stop actions is critical for navigating many daily life situations such as driving or social interactions. The current study investigated the speed of action initiation and two forms of action control, response stopping and proactive slowing in ET. Methods: Thirty-three ET patients and 25 healthy controls (HCs) completed a choice reaction task and a stop-signal task, and measures of going speed, proactive slowing and stop latencies were assessed. Results: Going speed was significantly slower in ET patients (649 ms) compared to HCs (526 ms; F(1,56) = 42.37; p <.001; η2 = .43), whereas proactive slowing did not differ between groups. ET patients exhibited slower stop signal reaction times (320 ms) compared to HCs (258 ms, F(1,56) = 15.3; p <.00; η2 = .22) and more severe motor symptoms of ET were associated with longer stopping latencies in a subset of patients (Spearman rho = .48; p <.05). Conclusions: In line with previous studies, ET patients showed slower action initiation. Additionally, inhibitory control was impaired whereas proactive slowing remained intact relative to HCs. More severe motor symptoms of ET were associated with slower stopping speed, and may reflect more progressive changes to the cerebellar-thalamo-cortical network. Future imaging studies should specify which structural and functional changes in ET can explain changes in inhibitory action control. (JINS, 2019, 25, 156–164)

The concept of a mixing efficiency is widely used to relate the amount of irreversible diabatic mixing in a stratified flow to the amount of energy available to support mixing. This common measure of mixing in a flow is based on the change in the background potential energy, which is the minimum gravitational potential energy of the fluid that can be achieved by an adiabatic rearrangement of the instantaneous density field. However, this paper highlights examples of mixing that is primarily ‘buoyancy-driven’ (i.e. energy is released to the flow predominantly from a source of available potential energy) to demonstrate that the mixing efficiency depends not only on the specific characteristics of the turbulence in the region of the flow that is mixing, but also on the density profile in regions remote from where mixing physically occurs. We show that this behaviour is due to the irreversible and direct conversion of available potential energy into background potential energy in those remote regions (a mechanism not previously described). This process (here termed ‘relabelling’) occurs without requiring either a local flow or local mixing, or any other process that affects the internal energy of that fluid. Relabelling is caused by initially available potential energy, associated with identifiable parcels of fluid, becoming dynamically inaccessible to the flow due to mixing elsewhere. These results have wider relevance to characterising mixing in stratified turbulent flows, including those involving an external supply of kinetic energy.

This case control study investigated environmental factors in 74 confirmed cases of meningococcal disease (MD). In children aged under 5, passive smoking in the home (30 or more cigarettes daily) was associated with an odds ratio (OR) of 7.5 (95% confidence interval (CI) 1.46–38.66). ORs increased both with the numbers of cigarettes smoked and with the number of smokers in the household, suggesting a dose–response relationship. MD in this age group was also significantly associated with household overcrowding (more than 1.5 persons per room) (OR 6.0, 95% CI 1.10–32.8), with kisses on the mouth with 4 or more contacts in the previous 2 weeks (OR 2.46, 95% CI 1.09–5.56), with exposure to dust from plaster, brick or stone in the previous 2 weeks (OR 2.24, 95% CI 1.07–4.65); and with changes in residence (OR 3.0, 95% CI 1.0–8.99), marital arguments (OR 3.0, 95 % CI 1.26–7.17) and legal disputes in the previous 6 months (OR 3.10, 95% CI 1.24–7.78). These associations were independent of social class. Public health measures to lower the prevalence of cigarette smoking by parents of young children may reduce the incidence of MD. The influence of building dust and stressful life events merits further investigation.

A turbulent plume from a continuous source of buoyancy in a long tank is shown to generate a series of quasi-steady counterflowing horizontal shear layers throughout the tank. Both the horizontal flow velocity and the depth of the shear layers are observed to decrease with distance above/below the plume outflow. The shear layers are supported by the stable density stratification produced by the plume and are superimposed on the vertical advection and entrainment inflow that make up the so-called ‘filling box’ circulation. Thus, at some depths, the surrounding water flows away from the plume instead of being entrained, although we see no evidence of ‘detrainment’ of dense plume water. Given the stratification produced by the plume at large times, the timescale for the velocity structure to adjust to changes in forcing is proportional to the time for long internal gravity waves to travel the length of the tank. The shear layers are interpreted in terms of internal normal modes that are excited by, and which in turn determine, the horizontal plume outflow. The sixth and seventh baroclinic modes typically dominate because at the level of the plume outflow their phase speed is approximately equal and opposite to the vertical advection in the ‘filling box’. Also, the approximate balance between phase speed and advection is found to hold throughout the tank, resulting in the observed quasi-steady flow structure. Viscosity causes the horizontal velocity in the shear layers to decrease with distance above/below the plume outflow, and is thought to be responsible for a low-frequency oscillation in the flow structure that is observed during experiments.

We present measurements of the density and velocity fields produced when an oscillating circular cylinder excites internal gravity waves in a stratified fluid. These measurements are obtained using a novel, non-intrusive optical technique suitable for determining the density fluctuation field in temporally evolving flows which are nominally two-dimensional. Although using the same basic principles as conventional methods, the technique uses digital image processing in lieu of large and expensive parabolic mirrors, thus allowing more flexibility and providing high sensitivity: perturbations of the order of 1% of the ambient density gradient may be detected. From the density gradient field and its time derivative it is possible to construct the perturbation fields of density and horizontal and vertical velocity. Thus, in principle, momentum and energy fluxes can be determined.

In this paper we examine the structure and amplitude of internal gravity waves generated by a cylinder oscillating vertically at different frequencies and amplitudes, paying particular attention to the role of viscosity in determining the evolution of the waves. In qualitative agreement with theory, it is found that wave motions characterized by a bimodal displacement distribution close to the source are attenuated by viscosity and eventually undergo a transition to a unimodal displacement distribution further from the source. Close quantitative agreement is found when comparing our results with the theoretical ones of Hurley & Keady (1997). This demonstrates that the new experimental technique is capable of making accurate measurements and also lends support to analytic theories. However, theory predicts that the wave beams are narrower than observed, and the amplitude is significantly under-predicted for low-frequency waves. The discrepancy occurs in part because the theory neglects the presence of the viscous boundary layers surrounding the cylinder, and because it does not take into account the effects of wave attenuation resulting from nonlinear wave–wave interactions between the upward and downward propagating waves near the source.

Because of the evidence that growth hormone gene transfer in pigs and mice can result in widespread pathological changes and more general concerns that transgenesis techniques themselves may have deleterious effects, a study was undertaken to compare the behaviour of two populations of immature female sheep, one of transgenic and one of control animals. The gene transferred was that for human alpha-1 antitrypsin factor. In the first part of the study the behaviour of 25 transgenic (T) and 25 control (C) sheep was compared in three separate situations: competition for a limited quantity of supplementary concentrate, six categories of normal behaviour on pasture and movement order when driven through a crush. With two minor exceptions (idling and ‘other’ behaviour in focally sampled animals), none of the differences observed between the two populations was significant and in most cases the mean values observed for T and C sheep were very similar. In the second part 25 T and 25 C sheep (different individuals from those in part 1) were compared in straw-littered covered pens for both normal behaviour and competition for a complete diet provided in a trough. The only significant differences in the seven categories of normal behaviour were a lower incidence of idling and ‘other’ behaviour in T sheep. There was a difference between T and C sheep in their social interaction under very competitive conditions (the T sheep reached food less quickly). The behavioural differences found in this study were all slight. Overall, the findings suggest that the gene transferred had no detectable deleterious effects on the normal behaviour of immature animals.

Films of GaN have been grown using a modified MBE method in which the active nitrogen is supplied from an RF activated plasma source. Wurtzite films grown on (0 0 1) oriented GaAs substrates show highly defective, ordered polycrystalline growth with a columnar structure; the (0 0 0 1) planes of the layers being parallel to the (0 0 1) planes of the GaAs substrate. Films grown using a coincident As flux, however, have a single crystal zinc-blende growth mode. They have better structural and optical properties. To improve the properties of the wurtzite films we have studied the growth of such films on (1 1 1)A and (1 1 1)B oriented GaAs substrates. The improved structural properties of such films, assessed using x-ray and TEM methods, correlate with better low temperature PL performance.

If flux density variability is intrinsic to extragalactic sources, then the shortest time scale of the variability yields an extremely high angular resolution. There is, however, good evidence that some of the variability is due to refractive scintillation in our galaxy's interstellar plasma turbulence. The effect, initially discovered at low radio frequencies, is here shown to extend into the GHz band, which, up to now, has been assumed to display only the intrinsic variability. We conclude that further study in both the intermediate and high frequency bands needed to separate the intrinsic and extrinsic components of variability.