Flow in sidewall cerebral aneurysms can be ideally modelled as the combination of flow over a spherical cavity and flow in a curved circular pipe, two canonical flows. Flow in a curved pipe is known to depend on the Dean number $De$, combining the effects of Reynolds number $\textit {Re}$ and of the curvature along the pipe centreline, $\kappa$. Pulsatility in the flow introduces a dependence on the Womersley number $Wo$. Using stereo particle image velocimetry measurements, this study investigated the effect of these three key non-dimensional parameters, by modifying pipe curvature ($De$), flow rate ($Re$) and pulsatility frequency ($Wo$), on the flow patterns in a spherical cavity. A single counter-rotating vortex was observed in the cavity for all values of pipe curvature $\kappa$ and Reynolds number $\textit {Re}$, for both steady and pulsatile inflow conditions. Increasing the pipe curvature impacted the flow patterns in both the pipe and the cavity, by shifting the velocity profile towards the cavity opening and increasing the flow rate in to the cavity. The circulation in the cavity was found to collapse well with only the Dean number, for both steady and pulsatile inflows. For pulsatile inflow, the counter-rotating vortex was unstable and the location of its centre over time was impacted by the curvature of the pipe, as well as $\textit {Re}$ and $Wo$ in the free stream. The circulation in the cavity was higher for steady inflow than for the equivalent average Reynolds number and Dean number pulsatile inflow, with very limited impact of the Womersley number in the range studied. A second part of this study, that focuses on the changes in fluid dynamics when the intracranial aneurysm is treated with a flow-diverting stent, can be found in this issue (Barbour et al., J. Fluid Mech., vol. 915, 2021, A124).

The flow in a spherical cavity on a curved round pipe is a canonical flow that describes well the flow inside a sidewall aneurysm on an intracranial artery. Intracranial aneurysms are often treated with a flow-diverting stent (FDS), a low-porosity metal mesh that covers the entrance to the cavity, to reduce blood flow into the aneurysm sac and exclude it from mechanical stresses imposed by the blood flow. Successful treatment is highly dependent on the degree of reduction of flow inside the cavity, and the resulting altered fluid mechanics inside the aneurysm following treatment. Using stereoscopic particle image velocimetry, we characterize the fluid mechanics in a canonical configuration representative of an intracranial aneurysm treated with a FDS: a spherical cavity on the side of a curved round pipe covered with a metal mesh formed by an actual medical FDS. This porous mesh coverage is the focus of Part 2 of the paper, characterizing the effects of parent vessel $Re$, $De$ and pulsatility, $Wo$, on the fluid dynamics, compared with the canonical configuration with no impediments to flow into the cavity that is described in Part 1 (Chassagne et al., J. Fluid Mech., vol. 915, 2021, A123). Coverage with a FDS markedly reduces the flow $Re$ in the aneurysmal cavity, creating a viscous-dominated flow environment despite the parent vessel $Re>100$. Under steady flow conditions, the topology that forms inside the cavity is shown to be a function of the parent vessel $De$. At low values of $De$, flow enters the cavity at the leading edge and remains attached to the wall before exiting at the trailing edge, a novel behaviour that was not found under any conditions of the high-$Re$, unimpeded cavity flow described in Part 1. Under these conditions, flow in the cavity co-rotates with the direction of the free-stream flow, similar to Stokes flow in a cavity. As $De$ increases, the flow along the leading edge begins to separate, and the recirculation zone grows with increasing $De$, until, above $De \approx 180$, the flow inside the cavity is fully recirculating, counter-rotating with respect to the free-stream flow. Under pulsatile flow conditions, the vortex inside the cavity progresses through the same cycle – switching from attached and co-rotating with the free-stream flow at the beginning of the cycle (low velocity and positive acceleration) to separated and counter-rotating as $De$ reaches a critical value. The location of separation within the harmonic cycle is shown to be a function of both $De$ and $Wo$. The values of aneurysmal cavity $Re$ based on both the average velocity and the circulation inside the cavity are shown to increase with increasing values of $De$, while $Wo$ is shown to have little influence on the time-averaged metrics. As $De$ increases, the strength of the secondary flow in the parent vessel grows, due to the inertial instability in the curved pipe, and the flow rate entering the cavity increases. Thus, the effectiveness of FDS treatment to exclude the aneurysmal cavity from the haemodynamic stresses is compromised for aneurysms located on high-curvature arteries, i.e. vessels with high $De$, and this can be a fluid mechanics criterion to guide treatment selection.

Places such as Poverty Point, Mound City, and Chaco Canyon remind us that the siting of ritual infrastructure in ancient North America was a matter of cosmological precedent. The cosmic gravity of these places gathered persons periodically in numbers that challenged routine production. Ritual economies intensified, but beyond the material demands of hosting people, the siting of these places and the timing of gatherings were cosmic work that preconfigured these outcomes. A first millennium AD civic-ceremonial center on the northern Gulf Coast of Florida illustrates the rationale for holding feasts on the end of a parabolic dune that it shared with an existing mortuary facility. Archaeofauna from large pits at Shell Mound support the inference that feasts were timed to summer solstices. Gatherings were large, judging from the infrastructure in support of feasts and efforts to intensify production through oyster mariculture and the construction of a large tidal fish trap. The 250-year history of summer solstice feasts at Shell Mound reinforces the premise that ritual economies were not simply the amplification of routine production. It also suggests that the ecological potential for intensification was secondary to the cosmic significance of solstice-oriented dunes and their connection to mortuary and world-renewal ceremonialism.

Research was conducted during 1988 and 1989 in Georgia and Florida to determine the densitydependent effects and critical periods of wild poinsettia interference with peanut. Peanut yield loss ranged from 0 to approximately 50% over the wild poinsettia density range from 0 to 32 plants 9 m−1 peanut row. Predicted peanut yield losses across 2 yr in Georgia were 0, 4, 8, 12, 15, 26, 40, and 54% for season-long wild poinsettia interference at densities of 0, 1, 2, 3, 4, 8, 16, and 32 plants 9 m−1 of row, respectively. Across 2 yr in Florida, predicted peanut yield losses were 0, 9, 14, 22, 30, 37, and 41% for wild poinsettia densities of 0, 1, 2, 4, 8, 16, and 32 plants 9 m−1 row, respectively. Peanuts had to be maintained poinsettia free for 10 wk after peanut emergence to prevent yield loss. Wild poinsettia that interfered with peanut for more than 2 wk after peanut emergence reduced peanut yield.

Background. Female nurses appear to have an increased risk of suicide but the reasons are unknown.

Method. We have concluded a study of nurse suicides (N = 106) in England and Wales, including a psychological autopsy study (N = 42) and case–control comparison with living nurses (N = 84).

Results. Nearly three-quarters of the nurse suicides had previous contact with psychiatric services and almost half had been psychiatric in-patients in the past. There were particularly marked differences between the cases and controls for current psychiatric disorder (90·5% v. 7·1%, OR = 68·5), personality disorder (38·1% v. 1·2%, OR = 32), and history of deliberate self-harm (71·4% v. 2· 4%, OR = 58·5). Family background and social factors (especially concerning interpersonal relationships) also distinguished the two groups. Smoking and serious alcohol abuse were much more frequent in the suicides. There was some indication that while many of the suicides were in contact with psychiatric services, care may not have been optimal in some cases.

Conclusions. The most important strategies for suicide prevention in nurses are in prevention, detection and management of psychiatric disorders. In assessing suicide risk a history of DSH and the presence of comorbid psychiatric and personality disorders are particularly important.

This article outlines the majority of the adverse physical effects that have been described secondary to the consumption of alcohol at levels above recommended sensible limits. These conditions are cited according to the organ system they belong to. Only brief descriptions are provided because of the vastness of this topic. The underlying pathophysiology of tolerance and withdrawal is touched upon as this is of relevance to the psychiatrist. Definitions of the terms used describing alcohol misuse, and sensible upper limits of alcohol consumption are also mentioned.

High purity Al samples were implanted with 35 keV Cl+ then polarized in Cl--free electrolyte in order to ascertain corrosion behavior as a function of Cl content. Electrochemical data indicated implant fluences between 5x1015 and 2x1016 Cl+cm-2 resulted in little or no localized attack. Implant fluences of 3x1016 and 5x1016 Cl+cm-2 resulted in significant attack with the severity scaling as a function of implant fluence. The low variability in the behavior of localized corrosion for the 5x1016 Cl+cm-2 sample suggests that this implant dosage may result in a critical Cl- in the sample for pit nucleation. Optical and Electron microscopy images indicated some reactivity associated with lower fluences (1x1016Cl+cm-2), possibly indicating enhanced general dissolution. At high magnification the corrosion was observed to occur outside the implanted boundary through mechanisms of tunneling or altered local chemistry at those sites. The SEM images reveal a form of localized corrosion with a crystalline character.

Copper is a critical material in electrical components and is subject to atmospheric sulfidation. This study characterized the product formed when Cu is exposed to a dilute (50-200ppb) H2S atmosphere at low (0.5%) to high (80%) relative humidity (RH). An important observation was that the Cu2S growth rate for long times is significantly higher for sulfides formed at low RH compared to high RH. In addition, it was found that for both low and high RH sulfidation, copper reacts to form the low chalcocite phase (Cu2S) as identified by x-ray and electron diffraction. Cross-section and plan-view TEM revealed that the Cu2S grains formed at high RH are 20-50 nm in size with a large amount of porosity, whereas the grains formed at low RH are 75-150+ nm and appear to undergo grain growth with little porosity as the film thickens.

We have used ion channeling to examine the lattice configuration of deuterium in Mg doped GaN grown by MOCVD. The deuterium is introduced by exposure to gas phase or ECR plasmas. A density functional approach including lattice relaxation, was used to calculate total energies for various locations and charge states of hydrogen in the wurtzite Mg doped GaN lattice. Results of channeling measurements are compared with channeling simulations for hydrogen at lattice locations predicted by density functional theory.

We have used ion channeling to examine the lattice configuration of deuterium in Mg doped GaN grown by MOCVD. The deuterium is introduced by exposure to gas phase or ECR plasmas. A density functional approach including lattice relaxation, was used to calculate total energies for various locations and charge states of hydrogen in the wurtzite Mg doped GaN lattice. Results of channeling measurements are compared with channeling simulations for hydrogen at lattice locations predicted by density functional theory.

Hydrogen in deposited optical ceramics can modify the optical properties, and therefore the role of the hydrogen needs to be understood to control its effects. Erbium-doped amorphous alumina films were deposited using simultaneous electron beam evaporation of aluminum and erbium while bombarding the sample with 30 eV 02+ ions from an electron cyclotron resonance (ECR) plasma. The hydrogen content was measured, using elastic recoil detection, as a function of isochronal annealing treatments. The data was fit to a simple trap-release model in order to determine an effective activation energy for the thermal release of H from alumina and Er-doped alumina. The intensity of the ion-beam stimulated luminescence from these samples was monitored in the visible and near infrared regions as a function of the thermal treatments. In order to gain a better understanding of the influence of hydrogen, the ionoluminescence (IL) data from samples containing hydrogen were fit with a simple linear equation.

The effects of low energy ions from a biased electron cyclotron resonance plasma during growth of Al2O3 and La2O3 are used to modify the density and crystalline quality of these oxide films. The type of phase formed for Al2O3 is varied with the ion-assisted growth from amorphous to crystalline γA12O3. The photoluminescence (PL) properties of different Er-doped Al- and La-oxide phases are examined, and through comparison of the PL spectra, the local environment of Er in these oxide materials is discussed.

lon implantation of O into Al and growth of Al(O) layers using electron-cyclotron resonance plasma and pulsed laser depositions produce composite alloys with a high density of nanometer-size oxide precipitates in an Al matrix. The precipitates impart high strength to the alloy and reduced adhesion during sliding contact, while electrical conductivity and ductility are retained. Implantation of N into Al produces similar microstructures and mechanical properties. The athermal energies of deposited atoms are a key factor in achieving these properties.

The thermal stability of fluorinated SiO2 films (SiOF) was found to be dependent on F content and the type of substrate upon which the film was deposited. SiOF films with a range of F concentrations were deposited using an electron cyclotron resonance (ECR) plasma upon Si, Al/Si, TiN/Al/Si, and Al/SiO2/Si substrates. Following deposition, the films were deliberately hydrated and/or annealed and their stability assessed. Hydration was found to only affect the high F content films. Capacitance changes with annealing in the high F content films were found to occur beginning at 200°C. These changes, which were independent of substrate type, likely occurred due to desorption of H2O in the films. After annealing of the high F content films up to 400°C, a reduction in F content was found for SiOF films on some substrates. Significant reductions were found for SiOF films on Al/Si substrates, while little or no change was found for films on TiN/Al/Si, Al/SiO2/Si, or Si substrates. Local chemical analysis of those films which showed F reduction indicated that the F profile was approximately uniform throughout the layer and did not pile-up at the interface. The substrate-dependent thermal instability exhibited by these films suggests the chemical nature or qualities of the substrate may play a role in the F reduction reaction.

We present a methodology based on finite-element modeling of nanoindentation data to extract reliable and accurate mechanical properties from thin, hard films and surface-modified layers on softer substrates. The method deduces the yield stress, Young's modulus, and hardness from indentations as deep as 50% of the layer thickness.

The criteria for forming stable cavities by He implantation and annealing are examined for Si and GaAs. In Si, implanting at room temperature requires a minimum of 1.6 at.% He to form a uniformly dense layer of cavities after annealing at 700°C. Near this threshold, cavities are located at dislocations and planar defects. Peak He concentrations just above 1.6 at.% produce narrow layers of cavities at the projected range. In GaAs, room-temperature implantation followed by annealing results in exfoliation of the surface layer. Cavities were formed instead by implanting Ar followed by overlapping He, both at 400°C, with additional annealing at 400°C to outgas the He. This method forms 1.5-3.5 nm cavities that are often on {111} planar defects.

The growth of polycrystalline and amorphous aluminum-oxygen alloy films using electronbeam evaporation of Al in the presence of an O2 electron-cyclotron-resonance (ECR) plasma was investigated for film compositions varying from 40% Al (A12O3) to near 100% Al (A1Ox). Processing parameters such as deposition temperature and ion energy were varied to study their effects on surface texture and film microstructure. The Al-rich films (AlOx) contain polycrystalline fcc Al grains with finely dispersed second-phase particles of γ-A12O3 (1–2 nm in size). The surface roughness of these films was measured by atomic force microscopy and found to increase with sample bias and deposition temperature. Stoichiometric A12O3 films grown at 100°C and 400°C without an applied bias were amorphous, while an applied bias of -140 V formed a nanocrystalline γ-A12O3 film at 400°C. The surface roughness of the A12O3 increased with temperature while ion irradiation produced a smoother surface