Strain, temperature and strain rate are crucial factors governing the development of crystallographic preferred orientations (CPO) in ice. To better understand how CPO patterns change in response to these variables, we performed quantitative analyses on neutron diffraction data between 2010 and 2019, collected in situ during uniaxial compression experiments on deuterium ice. At strains >10% and temperatures <−10°C, the c-axis pattern switches from a single maximum (‘cluster’) to small circle (‘cone’), both oriented parallel to shortening. The diameter and mean width of the cone pattern decrease as strain and/or strain rate increases. Prismatic axis (a and m) patterns are characterised by great circles parallel to the pole figure margin and may be distinguishable from the patterns in ice deformed under simple shear. While strain has the main influence on the degree of preferred orientation (or CPO ‘strength’), both temperature and strain rate have minor influences, which limits the extent to which CPOs can be used to measure strain. As cluster patterns can be observed in the c-axes of ice deformed under both pure and simple shear settings, this may complicate interpretations of flow geometry in terrestrial ice unless the prismatic axis patterns are also considered.

Early in the COVID-19 pandemic, the World Health Organization stressed the importance of daily clinical assessments of infected patients, yet current approaches frequently consider cross-sectional timepoints, cumulative summary measures, or time-to-event analyses. Statistical methods are available that make use of the rich information content of longitudinal assessments. We demonstrate the use of a multistate transition model to assess the dynamic nature of COVID-19-associated critical illness using daily evaluations of COVID-19 patients from 9 academic hospitals. We describe the accessibility and utility of methods that consider the clinical trajectory of critically ill COVID-19 patients.

Healthcare personnel with severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection were interviewed to describe activities and practices in and outside the workplace. Among 2,625 healthcare personnel, workplace-related factors that may increase infection risk were more common among nursing-home personnel than hospital personnel, whereas selected factors outside the workplace were more common among hospital personnel.

Starting in 2016, we initiated a pilot tele-antibiotic stewardship program at 2 rural Veterans Affairs medical centers (VAMCs). Antibiotic days of therapy decreased significantly (P < .05) in the acute and long-term care units at both intervention sites, suggesting that tele-stewardship can effectively support antibiotic stewardship practices in rural VAMCs.

Layered ice has been used to investigate the initiation of fabrics in shear zones where there is preservation of a refolded layering The fabrics were measured using an apparatus that acquires pixel-based images that illustrate the variation of c-axis orientation within and between grains. In the centre of the shear zones there is dynamic recrystallization with the production of an asymmetric two-maxima fabric. The way dynamic recrystallization modifies the inherited folds and microstructure suggests that there is little effect of inheritance from a precursor grain microstructure or fabric No obvious evidence has been found for the occurrence of sub-grains, which implies that the role of sub-grain rotation is minimal or is obliterated by the recrystallization process. The final c-axis pattern is asymmetric with respect to the direction of shortening, with a strong maximum at ~5° to the pole of the shear zone, and a sense of asymmetry in the direction of the shear, and a secondary maximum inclined at ~45° to the plane of shearing. Distinct sets of nearest-neighbour c-axis distributions, namely, intermediate-angle (10–25°), high-angle (50–65°) and very high-angle (120–150°), suggest there may be special grain-boundary relationships.

Using a series of combined compression–simple-shear experiments, it has been possible to investigate strain distributions and crystal-orientation fabrics related to varying layer orientation in ice. A variety of flattening strains accompanied by layer buckling, simple shear and the development of a lenticular layering are produced in anisotropic ice masses. In samples where the creep curve has only just reached a minimum strain rate, the c-axis preferred orientation is similar to that in the starting material, with specific c-axis concentrations affected by the extent of preserved host grains. At shear strains where γ ≤ 1, it was found that the c-axis preferred orientations were highly variable depending on the magnitude of strain, strain distribution and upon the modification and degree of rotation of initial c-axis preferred orientation. However, once recrystallization dominates in high-strain zones (γ ≥ 1), there is a rapid development of an asymmetric two-maxima fabric with little evidence of any contributions from inherited fabric elements. The final c-axis pattern is asymmetric with respect to the direction of shortening, with a strong maximum at ∼80° to the shear zone, with a sense of asymmetry in the direction of the shear, and a secondary maximum lying at ∼50° to the plane of shearing.

Two holes were drilled to depths greater than 300m in the Antarctic ice sheet, near Cape Folger on the Law Dome. The holes underwent considerable closure below 250m with localized strain-rates as high as 1 to 1.5×10−6 s−1. The closure observed in holes was non-uniform and occurred in zones 0.5 to 3 m wide. These Zones parallel the flow plane in the ice mass and are associated with a distinct domainal structure. High-closure zones are characterized by interlocking and irregular-shaped ice grains with many sub-horizontal c-axes and only occasional c-axis clusters at a high angle to the flow plane. Low-closure zones contain tabular grains with the long dimension parallel to the flow plane, abundant deformation features and a predominance of c-axes oriented at a high angle to the flow plane. The relationship between closure rate and c-axis fabric is attributed to marked plastic flow by intracrystalline slip on the basal plane to produce higher closure in areas where there is a greater variation in c-axis orientation. This deformation is attributable to overburden pressure and hence is related to depth, and is independent of shear within the main body of the ice mass.

Microstructural changes in three sets of experiments involving crystallographic slip in anisotropic polycrystalline ice are described and interpreted with the aid of computer models. The development of microstructure was followed using time-lapse photography and transmitted light observations with deformation undertaken in plane strain and at a temperature of approximately –1°C. The deformation within a grain aggregate that accompanies axial shortening is always heterogeneous on a grainscale. The extent of inhomogeneity varies depending on the pre-existing grain structure and the way it can accommodate intragranular slip. Grain interactions are extremely important in determining the bulk deformation and the degree of grain-boundary migration. A consequence of shortening of the aggregate is the formation of high stresses between neighbouring grains and under the appropriate conditions there may be either grain-boundary migration or melting at these sites. Where a sample undergoes translation and shear during deformation, anisotropic grains in the appropriate orientation undergo bending. A buckle instability may then develop and much of the strain is accommodated by grains in easy-glide orientations. In such situations, the ice undergoes extensive recrystallization and grain growth that is concentrated in the areas of greatest buckling.

Understanding the nutritional demands on serving military personnel is critical to inform training schedules and dietary provision. Troops deployed to Afghanistan face austere living and working environments. Observations from the military and those reported in the British and US media indicated possible physical degradation of personnel deployed to Afghanistan. Therefore, the present study aimed to investigate the changes in body composition and nutritional status of military personnel deployed to Afghanistan and how these were related to physical fitness. In a cohort of British Royal Marines (n 249) deployed to Afghanistan for 6 months, body size and body composition were estimated from body mass, height, girth and skinfold measurements. Energy intake (EI) was estimated from food diaries and energy expenditure measured using the doubly labelled water method in a representative subgroup. Strength and aerobic fitness were assessed. The mean body mass of volunteers decreased over the first half of the deployment ( − 4·6 (sd 3·7) %), predominately reflecting fat loss. Body mass partially recovered (mean +2·2 (sd 2·9) %) between the mid- and post-deployment periods (P< 0·05). Daily EI (mean 10 590 (sd 3339) kJ) was significantly lower than the estimated daily energy expenditure (mean 15 167 (sd 1883) kJ) measured in a subgroup of volunteers. However, despite the body mass loss, aerobic fitness and strength were well maintained. Nutritional provision for British military personnel in Afghanistan appeared sufficient to maintain physical capability and micronutrient status, but providing appropriate nutrition in harsh operational environments must remain a priority.