The complexity of flow and wide variety of depositional processes operating in subaqueous density flows, combined with post‐depositional consolidation and soft‐sediment deformation, often make it difficult to interpret the characteristics of the original flow from the sedimentary record. This has led to considerable confusion of nomenclature in the literature. This paper attempts to clarify this situation by presenting a simple classification of sedimentary density flows, based on physical flow properties and grain‐support mechanisms, and briefly discusses the likely characteristics of the deposited sediments. Cohesive flows are commonly referred to as debris flows and mud flows and defined on the basis of sediment characteristics. The boundary between cohesive and non‐cohesive density flows (frictional flows) is poorly constrained, but dimensionless numbers may be of use to define flow thresholds. Frictional flows include a continuous series from sediment slides to turbidity currents. Subdivision of these flows is made on the basis of the dominant particle‐support mechanisms, which include matrix strength (in cohesive flows), buoyancy, pore pressure, grain‐to‐grain interaction (causing dispersive pressure), Reynolds stresses (turbulence) and bed support (particles moved on the stationary bed). The dominant particle‐support mechanism depends upon flow conditions, particle concentration, grain‐size distribution and particle type. In hyperconcentrated density flows, very high sediment concentrations (>25 volume%) make particle interactions of major importance. The difference between hyperconcentrated density flows and cohesive flows is that the former are friction dominated. With decreasing sediment concentration, vertical particle sorting can result from differential settling, and flows in which this can occur are termed concentrated density flows. The boundary between hyperconcentrated and concentrated density flows is defined by a change in particle behaviour, such that denser or larger grains are no longer fully supported by grain interaction, thus allowing coarse‐grain tail (or dense‐grain tail) normal grading. The concentration at which this change occurs depends on particle size, sorting, composition and relative density, so that a single threshold concentration cannot be defined. Concentrated density flows may be highly erosive and subsequently deposit complete or incomplete Lowe and Bouma sequences. Conversely, hydroplaning at the base of debris flows, and possibly also in some hyperconcentrated flows, may reduce the fluid drag, thus allowing high flow velocities while preventing large‐scale erosion. Flows with concentrations <9% by volume are true turbidity flows (sensuBagnold, 1962), in which fluid turbulence is the main particle‐support mechanism. Turbidity flows and concentrated density flows can be subdivided on the basis of flow duration into instantaneous surges, longer duration surge‐like flows and quasi‐steady currents. Flow duration is shown to control the nature of the resulting deposits. Surge‐...

Bedforms and associated sedimentary structures, formed under supercritical water flow over an aggrading sand bed, were studied in a laboratory flume. Although the geometry and hydraulic characteristics of these bedforms (antidunes, chutes‐and‐pools) are well known, their internal structures are not. The objectives of the study were to: (1) describe the three‐dimensional geometry of the sedimentary structures and examine their mode of origin; (2) develop a relationship between the geometries of the sedimentary structures and the formative bedforms and; (3) identify criteria that distinguish these sedimentary structures from similar types, such as hummocky and swaley cross‐strata. Sedimentary structures associated with antidunes are primarily lenticular laminasets with concave‐upward erosional bases (troughs) in which laminae generally dip upstream or fill the troughs symmetrically. These laminasets are associated with growth and upstream migration of water‐surface waves and antidunes, and with surface‐wave breaking and filling of antidune troughs respectively. In addition, sets of downstream‐dipping laminae are produced by rapid migration of asymmetrical bedwaves immediately after wave breaking. Rare convex‐upward laminae define the shape of antidunes that developed under stationary water‐surface waves. The laminasets and internal laminae extend across the width of the flume, but vary in thickness and inclination, indicating that the antidunes have some degree of three dimensionality. The length and maximum thickness of the lenticular laminasets are approximately half of the length and height of formative antidunes, providing a potentially useful tool for palaeohydraulic reconstructions. The sets of downstream‐dipping laminae formed under antidunes are distinctive and do not occur in hummocky and swaley cross‐strata. Sedimentary structures associated with chutes‐and‐pools are sets of upstream‐dipping laminae and structureless sand.

The 4th edition of the Nordic Nutrition Recommendations, NNR 2004, gives the proportions between energy yielding nutrients, recommended daily intakes (RI) of certain vitamins and minerals, and reference values for energy intakes in different age and sex groups. Recommendations are also given for dietary fibre, salt and alcohol. Recommendations on daily physical activity are now included and interaction with physical activity has been taken into account for the individual nutrient recommendations wherever appropriate. For adults 30 minutes of daily physical activity of at least moderate intensity is recommended. More physical activity (about 60 minutes daily) with a moderate and/or vigorous intensity may be needed for prevention of weight gain. For children a minimum of 60 minutes of physical activity every day is recommended. As in the 3rd edition, the recommendation is to limit of the intake of saturated plus trans fatty acids to about 10% of the total energy intake (E%) and of the total fat intake to 30 E%. The intake of carbohydrate and dietary fibres should increase, while the intake of refined sugars should not exceed 10 E%. The RI for vitamin A (women) has been lowered, while it has been increased for vitamin D (children and adults up to 60 y), vitamin C (adults) and folate (women of reproductive age; pregnant and lactating women).NNR is to be used for planning and evaluation of diets, and as a basis for food and nutrition policy, teaching and dietary information.

Despite the widespread use of prenatal care, the evidence for its effectiveness remains equivocal and its primary purpose and effects continue to be a subject of debate. To provide some perspective on why the effectiveness and organization of prenatal care continue to be debated, the authors (a) briefly review the history of the development of prenatal care in the US; (b) attempt to conceptually define prenatal care in terms of its utilization, content, and quality; and, (c) highlight some of the research controversies and challenges facing investigators and advocates who seek to establish the value of prenatal care. In addition, the authors recommend directions for future research to address persistent questions regarding the function, structure, and significance of prenatal care in improving US perinatal outcomes.

Detailed three‐dimensional (3‐D) observations of sandy point‐bar deposits from the River South Esk in Scotland were made using very closely spaced (metres) vibracores and ground‐penetrating radar (GPR) profiles. In order to explain the origin of the observed patterns of deposition, use was made of previous studies of channel geometry, flow and sediment transport. In addition, the mode and nature of channel migration and point‐bar accretion were determined using published maps, aerial photographs and detailed topographic surveys. Point‐bar deposits accumulated in response to channel‐bend expansion and downstream migration, resulting in preservation of sequences that fine upwards and downstream. Lower‐bar deposits are mainly very‐coarse to coarse sands with medium‐scale trough cross‐strata overlying basal gravels: associated radar facies are generally low‐amplitude, relatively discontinuous inclined reflectors. Upper‐bar deposits are mainly fine to medium sands with medium‐ and small‐scale cross‐strata and vegetation‐rich layers: associated radar facies are generally moderate‐ to high‐amplitude, laterally continuous, inclined reflectors. Large‐scale inclined stratasets seen in GPR profiles resulted from episodic point‐bar accretion. Abrupt lateral changes in inclination of these stratasets, and preservation of distinct unit bars (bar heads, scroll bars), lower‐bar platforms and inner‐bank swale fills, record discrete episodes of erosion and deposition associated with floods with recurrence intervals of decades to centuries. Such detailed 3‐D description and interpretation of these large‐scale features of point‐bar deposits was only possible through the use of GPR profiles tied closely to cores, and through the availability of much previously collected information on channel geometry, water flow, sediment transport, erosion and deposition.