The granular monoclinal wave

We study granular chute flow using the classic Saint-Venant approach, with the shear stresses within the granular sheet being incorporated via a friction law due to Pouliquen & Forterre (J. Fluid Mech., vol. 453, 2002, pp. 113–151) and with the in-plane stresses (which are ignored in the traditional formulation for normal fluids) being represented by a viscous-like term recently derived by Gray & Edwards (J. Fluid Mech., vol. 755, 2014, pp. 503–534). On the basis of this model, we predict that the granular sheet is able to sustain monoclinal waves, i.e. travelling shock structures that monotonically connect a thick region of uniform flow to a thinner one. We examine the balance of forces that determine the shape of this particular waveform and give the precise window of system parameters for which monoclinal waves are expected to appear in experiments.

The skeleton, support and movement

Buoyancy largely supports fish, reducing the role of the skeleton, which functions as an attachment for muscle involved in movement and in protection, as exoskeleton (scales, scutes, bony plates) and as endoskeleton (vertebral column, skull). The general organization of fish skeletons and their component parts are described, as well as bone and cartilage. The interesting occurrence of acellular bone, additional to cellular bone, in teleosts is considered. Fish show metameric segmentation with myotomes on either side of the vertebral column, the latter acting as a compression strut, preventing shortening. Myotome muscle is organized into linear units named sarcomeres which contract by means of protein fibres, myosin and actin, sliding past each other. Usually fish body wall muscles occur as a thin outer layer of aerobic red muscle, with an inner thick region of anaerobic white muscle. Interspecific variability in the relative roles of myotomes and fin musculature in swimming is discussed.

Constructing Peripheral Cross-Border Regions in Planning: Territory—Network Interplay in the Barents Region

This paper studies how supranational regions are built through the interplay of borders and networks. The focus is on how territory and network become manifest in planning, and in particular on the actual contexts in planning where the territorial discourse is emphasized. Conceptually, territory–network interplay is linked to recent discussions on relational/territorial space, multidimensionality of sociospatial relations, and thin and thick region building. The Barents Euro-Arctic Region is used here as an example, and the region's recent geoeconomic turn is studied first. The paper concludes that, despite geoeconomization, network is not dominant over territory as a key category in supranational region building. Although the contemporary (new) regionalist planning discourse emphasizes the institutionalization of network-oriented regional (economic) spaces without definitive boundaries, processes such as representing the region in branding or (re)defining who is eligible to join the official structures of cross-border cooperation entail a degree of territorial thinking and make use of the notions of boundedness and spatial symmetry. In planning practices networks commonly create the territory effect and vice versa. However, due to their different ontologies, network and territory can appear as separate or even contradictory discourses as well.

Estimates of the refreezing rate in an ice-shelf borehole

The refreezing rate of a borehole drilled through a 252 m thick region of the Ross Ice Shelf, Antarctica, is determined using oceanographic measurements over two periods of a day. We first use a method based on the conservation of salt in the supercooled salt water of the borehole. This is compared to a model using a numerical solution of the heat equation to find the temperature distribution in the host ice, allowing ice growth to be calculated from the balance of heat fluxes at the ice/water interface. This second method broadly confirms the refreezing rates deduced from salinity measurements, giving confidence in the generalization of this simple heat-flux model to predict refreezing rates of other boreholes. Predictions from both are subject to uncertainty due to the poorly defined value of the solid fraction of ice that freezes in a supercooled volume of sea water. This is taken to be 0.5 ± 0.1 throughout this study. The predicted rates are also strongly dependent on the initial and boundary conditions chosen, but results show the initial diameter of 600 mm decreases at a rate of ∼3–5 mm h−1 in an ice shelf with a minimum temperature of −22°C.

THERMAL DIFFUSIVITY OF Bi2Sr2CaCu2O8 CERAMICS WITH NANO Ag ADDITION MEASURED USING OPEN-CELL PHOTOACOUSTIC TECHNIQUE

This paper reports the results of thermal diffusivity measurement on nano Ag added Bi 2 Sr 2 CaCu 2 O 8- Ag x (with x = 0–1.0) ceramics using an open-cell photoacoustic instrument. The thermal diffusivities were obtained by analyzing the phase of the photo-acoustic signal of thermally thick samples using Calderon's method as well as the analysis of the phase in thermally thick region. We found that the thermal diffusivity increases with the amounts of nano Ag . The values of thermal diffusivity obtained were between 0.01250 ± 0.00128 to 0.01606 ± 0.00230 cm 2/ s for Ag 0 to Ag 1.0. The electrical resistance versus temperature measurements showed a metal-like behavior for all samples. However, a metal-like transition was observed between x = 0.5 and 0.7 when results of thermal diffusivity and electrical resistance measurements were analyzed together with samples x ≥ 0.7 showing the metallic behavior.

Properties of the Core-Mantle Boundary

The core-mantle boundary (CMB), separating the molten metallic core from the overlying solid silicate mantle, marks the largest discontinuity in mechanical properties within the Earth. The ∼ 200 km thick region just above the CMB, named D″ by Bullen (1950), is characterized by an anomalous gradient in seismic velocity versus depth. D″ was originally interpreted as a region with a strong compositional gradient due to the accumulation of dense material at the base of the mantle. Subsequently, the anomalous gradient was interpreted as the result of a strong temperature gradient in a hot thermal boundary layer at the base of the mantle, an interpretation motivated by the requiremnet that heat involved in generating the geodynamo must be transported out of the core and through the mantle by convection.

Optical Evidence for a Dust Ring in the Centre of M 82 and (OR?) a Flat Star Burst Region

A dust ring surrounds the central starburst region in M 82, resulting in strong additional reddening of light emerging near the equator. The starburst is contained in a flattened, optically thick region inside this ring. The concentration of scattered light near the minor axis is explained as the combined action of the cos ϑ-emission-law of the flat source and the shadowing by the ring. The dust ring may be spatially coincident with the CO-ring.