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Increasing ocean and air temperatures have contributed to the removal of floating ice shelves from several Greenland outlet glaciers; however, the specific contribution of these external forcings remains poorly understood. Here we use atmospheric, oceanographic and glaciological time series data from the ice shelf of Petermann Gletscher, NW Greenland to quantify the forcing of the ocean and atmosphere on the ice shelf at a site ~16 km from the grounding line within a large sub-ice-shelf channel. Basal melt rates here indicate a strong seasonality, rising from a winter mean of 2 m a−1 to a maximum of 80 m a−1 during the summer melt season. This increase in basal melt rates confirms the direct link between summer atmospheric warming around Greenland and enhanced ocean-forced melting of its remaining ice shelves. We attribute this enhanced melting to increased discharge of subglacial runoff into the ocean at the grounding line, which strengthens under-ice currents and drives a greater ocean heat flux toward the ice base.
Being born small for gestational age (SGA) is considered a developmental vulnerability. Alternatively, SGA may be viewed as a marker for individual susceptibility to environmental experiences. The aim was to test if individuals born SGA are more susceptible to both negative and positive environmental experiences assessed by sensitive parenting in childhood compared with those born appropriate for gestational age (AGA). The target outcome was wealth in young adulthood. A total of 438 participants (SGA, n = 109; AGA, n = 329) were studied as part of the prospective Bavarian Longitudinal Study of neonatal at-risk children. Maternal sensitivity was observed during a standardized mother-child interaction task, and IQ was assessed with the Kaufman Assessment Battery for Children at age 6 years. At age 26, participants’ wealth was assessed with a comprehensive composite score. Individuals born SGA were found to be more susceptible to the effects of sensitive parenting after controlling for gestational age and IQ at age 6 years. When maternal sensitivity was lower than average, SGA adults did worse than AGA adults, but when exposed to above-average maternal sensitivity in childhood, they obtained significantly higher wealth than their AGA peers by 26 years of age.
Direct numerical simulations (DNS) of controlled H- and K-type transitions to turbulence in an
$M = 0.2$
is the Mach number) nominally zero-pressure-gradient and spatially developing flat-plate boundary layer are considered. Sayadi, Hamman & Moin (J. Fluid Mech., vol. 724, 2013, pp. 480–509) showed that with the start of the transition process, the skin-friction profiles of these controlled transitions diverge abruptly from the laminar value and overshoot the turbulent estimation. The objective of this work is to identify the structures of dynamical importance throughout the transitional region. Dynamic mode decomposition (DMD) (Schmid, J. Fluid Mech., vol. 656, 2010, pp. 5–28) as an optimal phase-averaging process, together with triple decomposition (Reynolds & Hussain, J. Fluid Mech., vol. 54 (02), 1972, pp. 263–288), is employed to assess the contribution of each coherent structure to the total Reynolds shear stress. This analysis shows that low-frequency modes, corresponding to the legs of hairpin vortices, contribute most to the total Reynolds shear stress. The use of composite DMD of the vortical structures together with the skin-friction coefficient allows the assessment of the coupling between near-wall structures captured by the low-frequency modes and their contribution to the total skin-friction coefficient. We are able to show that the low-frequency modes provide an accurate estimate of the skin-friction coefficient through the transition process. This is of interest since large-eddy simulation (LES) of the same configuration fails to provide a good prediction of the rise to this overshoot. The reduced-order representation of the flow is used to compare the LES and the DNS results within this region. Application of this methodology to the LES of the H-type transition illustrates the effect of the grid resolution and the subgrid-scale model on the estimated shear stress of these low-frequency modes. The analysis shows that although the shapes and frequencies of the low-frequency modes are independent of the resolution, the amplitudes are underpredicted in the LES, resulting in underprediction of the Reynolds shear stress.
Case studies contribute more focused analyses which, in the context of human loss and damage, demonstrate the effectiveness of response strategies and prevention measures and identify lessons about success in disaster risk reduction and climate change adaptation. The case studies were chosen to complement and be consistent with the information in the preceding chapters, and to demonstrate aspects of the key messages in the Summary for Policymakers and the Hyogo Framework for Action Priorities.
The case studies were grouped to examine types of extreme events, vulnerable regions, and methodological approaches. For the extreme event examples, the first two case studies pertain to events of extreme temperature with moisture deficiencies in Europe and Australia and their impacts including on health. These are followed by case studies on drought in Syria and dzud, cold-dry conditions in Mongolia. Tropical cyclones in Bangladesh, Myanmar, and Mesoamerica, and then floods in Mozambique are discussed in the context of community actions. The last of the extreme events case studies is about disastrous epidemic disease, using the case of cholera in Zimbabwe, as the example.
The case studies chosen to reflect vulnerable regions demonstrate how a changing climate provides significant concerns for people, societies, and their infrastructure. These are: Mumbai as an example of a coastal megacity; the Republic of the Marshall Islands, as an example of small island developing states with special challenges for adaptation; and Canada's northern regions as an example of cold climate vulnerabilities focusing on infrastructures.
The emergence of a reading public for American fiction was, as chapter 36 shows, a gradual and often contested one. And even as audiences for novels and short stories grew, continuing worries about the moral “dangers” of fiction were compounded by the appearance of new modernist forms which called in question the most fundamental conventions of imaginative narration. Modernism would mean many things, but in its deepest impulse it sought radical alternatives to the novelistic realism that by the beginning of the new century had become fiction's dominant mode. Gertrude Stein, born one year after the publication of Harriet Beecher Stowe's A Library of Famous Fiction, would lead a modernist assault on familiar notions of character and action in the novel that would also shape the hugely influential but very different writing of her most famous pupil, Ernest Hemingway.
Stein's principal complaint about nineteenth-century fiction was that it made narration the creature of memory; as she put it in a 1934 lecture called “Portraits and Repetition”:
slowly I realized this confusion, a real confusion, that in writing a story one had to be remembering, and that novels are soothing because so many people one may say everybody can remember almost anything. It is this element of remembering that makes novels so soothing. But and that was the thing that I was gradually finding out listening and talking at the same time that is realizing the existence of living being actually existing did not have in it any element of remembering and so the time of existing was not the same as in the novels that were soothing.
Vegetable oils (VO) have become the predominant substitute for fish oil (FO) in aquafeeds; however, the resultant lower content of n-3 long-chain ( ≥ C20) PUFA (n-3 LC-PUFA) in fish has put their use under scrutiny. The need to investigate new oil sources exists. The present study tested the hypothesis that in Atlantic salmon (Salmo salar L.), a high intake of stearidonic acid (SDA) from Echium oil (EO) would result in increased n-3 LC-PUFA biosynthesis due to a lower requirement for Δ6 desaturase. Comparisons were made with fish fed on diets containing rapeseed oil (RO) and FO in freshwater for 112 d followed by 96 d in seawater. EO fish had higher whole-carcass SDA and eicosatetraenoic acid (ETA) in freshwater and prolonged feeding on the EO diet in seawater resulted in higher SDA, ETA, EPA and docosapentaenoic acid (DPA) compared with RO fish. Fatty acid mass balance of freshwater fish indicated higher biosynthesis of ETA and EPA in EO fish compared with fish fed on the other diets and a twofold increase in n-3 LC-PUFA synthesis compared with RO fish. In seawater, n-3 biosynthetic activity was low, with higher biosynthesis of ETA in EO fish and appearance of all desaturated and elongated products along the n-3 pathway. SDA-enriched VO are more suitable substitutes than conventional VO from a human consumer perspective due to the resulting higher SDA content, higher total n-3 and improved n-3:n-6 ratio obtained in fish, although both VO were not as effective as FO in maintaining EPA and DHA content in Atlantic salmon.
Whether the density of sarcoplasmic reticulum (SR) calcium release channels / ryanodine receptors in the heart declines with age is not clear. We investigated age-related changes in the density of «3H»-ryanodine receptors in crude ventricular homogenates, which contained all ligand binding sites in heart and in isolated junctional SR membranes. Experiments utilized young (120 days) and older adult (300 days) hamsters. «3H»-ryanodine binding site density did not change with age in crude homogenate preparations, although total heart protein concentration increased significantly with age. In contrast, the density of «3H»-ryanodine binding sites decreased markedly in heavy SR membranes purified from older hearts. These results show that demonstration of age-related changes in cardiac ryanodine receptor density depends upon the preparation used. Furthermore, the increase in total ventricular protein with age suggests that normalization of data by membrane protein should be used with caution in studies of aging heart.
Coastal areas are densely populated and highly productive regions and any changes to them could have profound direct and indirect impacts on coastal societies. The geological and historical record shows that coasts are always evolving. Hence, global environmental change (climate, sea level, water use and land use changes) expected this century (Crossland et al., 2005; IPCC, 2007a) would modify coastal evolutionary behaviour at local, regional and landscape scales with important consequences. These modifications may lead to (1) accelerations in rates of coastal change (e.g. acceleration in erosional (dominant) and accretional (exceptional) trends), (2) reversals in historical trends (e.g. accreting coasts becoming erosive), or (3) initiation of state or mode changes in coastal behaviour (e.g. dune breaching and formation of new tidal basins).
Prediction of accelerations may and should draw on historical data to extrapolate future trends in some settings. Trend reversals and state or mode changes, however, will require sufficient understanding of coastal morphodynamics to allow predictions of future change from the combined application of historical geomorphologic data and morphodynamic models. As well as best estimates, there is a need to evaluate uncertainty in terms of probabilistic risk, and to generate future scenarios to characterise consequences at different levels of risk. The objective of risk-based prediction is to express forecasts in a form that bridges the gap between science and policy. Coastal change can cause major problems for society, especially if reversal of trends and state or mode changes of behaviour occur on coasts mistakenly regarded by the community as ‘fixed’. Methodological approaches such as those outlined in this chapter are essential to explore the full range of possible changes and hence to underpin design and choice of appropriate science-based management options.
Socioeconomic changes over the coming century are expected to be so great that direct anthropogenic effects are likely to be drivers of comparable or possibly even greater significance for coastal geomorphology than climate change impacts (Valiela, 2006; IPCC, 2007b, pp. 315 – 356).
The present review examines renewable sources of oils with n-3 long-chain ( ≥ C20) PUFA (n-3 LC-PUFA) as alternatives to oil from wild-caught fish in aquafeeds. Due to the increased demand for and price of wild-caught marine sources of n-3 LC-PUFA-rich oil, their effective and sustainable replacement in aquafeeds is an industry priority, especially because dietary n-3 LC-PUFA from eating fish are known to have health benefits in human beings. The benefits and challenges involved in changing dietary oil in aquaculture are highlighted and four major potential sources of n-3 LC-PUFA for aquafeeds, other than fish oil, are compared. These sources of oil, which contain n-3 LC-PUFA, specifically EPA (20 : 5n-3) and DHA (22 : 6n-3) or precursors to these key essential fatty acids, are: (1) other marine sources of oil; (2) vegetable oils that contain biosynthetic precursors, such as stearidonic acid, which may be used by fish to produce n-3 LC-PUFA; (3) single-cell oil sources of n-3 LC-PUFA; (4) vegetable oils derived from oil-seed crops that have undergone genetic modification to contain n-3 LC-PUFA. The review focuses on Atlantic salmon (Salmo salar L.), because it is the main intensively cultured finfish species and it both uses and stores large amounts of oil, in particular n-3 LC-PUFA, in the flesh.
The stability and dynamics of an axisymmetric lifted flame are studied by means of direct numerical simulation (DNS) and linear stability analysis of the reacting low-Mach-number equations. For light fuels (such as non-premixed methane/air flames), the non-reacting premixing zone upstream of the lifted flame base contains a pocket of absolute instability supporting self-sustaining oscillations, causing flame flicker even in the absence of gravity. The liftoff heights of the unsteady flames are lower than their steady counterparts (obtained by the method of selective frequency damping (SFD)), owing to premixed flame propagation during a portion of each cycle. From local stability analysis, the lifted flame is found to have a significant stabilizing influence at and just upstream of the flame base, which can truncate the pocket of absolute instability. For sufficiently low liftoff heights, the truncated pocket of absolute instability can no longer support self-sustaining oscillations, and the flow is rendered globally stable.
'Said Yo-Yo: / “What part ob yu iz deh poEM?”.' Tucked away in one of the late Cantos that Ezra Pound wrote during his thirteen-year incarceration in St Elizabeths hospital, this question from a fellow inmate is offered as light relief in a passage which has already praised Adolf Hitler as a leader 'furious from perception'. In such a context, readers are unlikely to linger over Yo-Yo's question, cast as it is in a damaged idiom that serves only to reinforce the apparent obtuseness of its underlying assumption: Pound is a poet, ergo his poem must exist somewhere in his person. The association is silly, of course, though it has a certain irony when proposed in a place where bodies are hardly at their best. But, whether or not it is recorded here for that reason, Yo-Yo's question does remind us that, while a modernist poetics seems to emerge from a distrust of earlier conceptions of poetry as ethereal and disembodied, it is also founded in a partial and strategic dissociation of the poet from the poem. In light of this, to ask where the poem 'is' - to wonder which part of the poet's person it might seem to occupy - might prompt us to ask where it comes from in the first place, a question of a rather different order and one which may shed more light on modernist poetics than Yo-Yo could have suspected. Traditional answers to the conundrum frequently appeal to the function of memory, especially the Platonic form of recollection, and in practice, of course, especially in periods before our own, poetry did have close ties to memory, not least through the common practice of learning by heart.
The stability properties of round variable-density low-Mach-number jets are studied by means of direct numerical simulation (DNS) and linear stability analysis. Fully three-dimensional DNS of variable-density jets, with and without gravity, demonstrate that the presence of buoyancy causes a more abrupt transition to turbulence. This effect helps to explain differences between normal gravity and microgravity jet diffusion flames observed in the laboratory.
The complete spectrum of spatial eigenmodes of the linearized low-Mach-number equations is calculated using a global matrix method. Also, an analytic form for the continuous portion of this spectrum is derived, and used to verify the numerical method. The absolute instability of variable-density jets is confirmed using Brigg's method, and a comprehensive parametric study of the strength and frequency of this instability is performed. Effects of Reynolds number, the density ratio of ambient-to-jet fluid (S1), shear-layer thickness and Froude number are considered. Finally, a region of local absolute instability is shown to exist in the near field of the jet by applying linear stability analysis to mean profiles measured from DNS.