Senior leaders increasingly embed paradoxes into their organization's strategy, but struggle to manage them effectively. To better understand how they do so, I compared in-depth qualitative data from ...six top management teams exploring and exploiting simultaneously. The results informed a model of dynamic decision making in which strategic paradoxes can be effectively engaged. The details of this dynamic decisionmaking model extend and complicate our understanding of managing paradoxes by depicting dilemmas and paradoxes as interwoven, explicating a consistently inconsistent pattern of addressing tensions, and framing both differentiating and integrating practices as necessary for engaging paradox.
Nitrous oxide, N2O, is the third most important of the long‐lived greenhouse gases, in terms of its contribution to global warming, and is expected to be the dominant cause of stratospheric ozone ...depletion this century. The concentration of N2O in the atmosphere was fairly constant until the beginning of the industrial age, but has gone up by 20% since. This is because of increased anthropogenic emissions, of which about 60% come from agricultural soil. The cause is the increased use of synthetic fertilizer nitrogen globally to meet the demands for increased production of food and biofuels. This review examines the isotopic evidence for this role of fertilizer N, the main mechanisms for microbial production of N2O in soil, the key soil physical and other variables that greatly affect the magnitude of emissions, and the spatial and temporal variation in emissions and the associated problems of measurement. The review also considers the methodology devised by the Intergovernmental Panel on Climate Change (IPCC) to enable countries to compile national inventories of their emissions, direct and indirect, that arise from anthropogenic activity related to agriculture and land use. This methodology also enables modellers to make ‘bottom‐up’ global estimates of N2O emissions. These estimates agree quite well at the global scale with ‘top‐down’ estimates based on the relation between reactive nitrogen newly introduced into agricultural ecosystems and increases in the global atmospheric concentration of N2O, but not with some recent regional‐scale emission measurements. The discrepancy may be related to problems of estimating indirect emissions. Top‐down estimates indicate that N2O emissions from crop‐based biofuels are too great to comply with national and international environmental regulations. Finally, possible future trends in emissions and possible mitigation measures are discussed.
Highlights
Evidence for increasing N2O in the atmosphere suggests it is caused by fertilizer N use.
Agreements and inconsistencies in assessments of N2O emissions are considered.
The main cause of increasing N2O is the use of synthetic N fertilizers on agricultural soil worldwide.
Indirect emissions from waters receiving leached N may be a major cause of assessment uncertainties.
The primary productivity of the Southern Ocean ecosystem is limited by iron availability. Away from benthic and aeolian sources, iron reaches phytoplankton primarily when iron-rich subsurface waters ...enter the euphotic zone. Here, eddy-resolving physical/biogeochemical simulations of a seasonally-forced, open-Southern-Ocean ecosystem reveal that mesoscale and submesoscale isopycnal stirring effects a cross-mixed-layer-base transport of iron that sustains primary productivity. The eddy-driven iron supply and consequently productivity increase with model resolution. We show the eddy flux can be represented by specific well-tuned eddy parametrizations. Since eddy mixing rates are sensitive to wind forcing and large-scale hydrographic changes, these findings suggest a new mechanism for modulating the Southern Ocean biological pump on climate timescales.
This review explores supramolecular gels as materials for environmental remediation. These soft materials are formed by self-assembling low-molecular-weight building blocks, which can be programmed ...with molecular-scale information by simple organic synthesis. The resulting gels often have nanoscale 'solid-like' networks which are sample-spanning within a 'liquid-like' solvent phase. There is intimate contact between the solvent and the gel nanostructure, which has a very high effective surface area as a result of its dimensions. As such, these materials have the ability to bring a solid-like phase into contact with liquids in an environmental setting. Such materials can therefore remediate unwanted pollutants from the environment including: immobilisation of oil spills, removal of dyes, extraction of heavy metals or toxic anions, and the detection or removal of chemical weapons. Controlling the interactions between the gel nanofibres and pollutants can lead to selective uptake and extraction. Furthermore, if suitably designed, such materials can be recyclable and environmentally benign, while the responsive and tunable nature of the self-assembled network offers significant advantages over other materials solutions to problems caused by pollution in an environmental setting.
Self-assembled gels have nanoscale 'solid-like' networks spanning across a liquid-like phase and are ideally suited for bringing these into intimate contact with polluted solution-phase media in an environmental setting, with the ultimate goal of environmental remediation.
From microbes to large predators, there is increasing evidence that marine life is shaped by short-lived submesoscales currents that are difficult to observe, model, and explain theoretically. ...Whether and how these intense three-dimensional currents structure the productivity and diversity of marine ecosystems is a subject of active debate. Our synthesis of observations and models suggests that the shallow penetration of submesoscale vertical currents might limit their impact on productivity, though ecological interactions at the submesoscale may be important in structuring oceanic biodiversity.
Aims and scope
The usage of mobile phones and the internet by young people has increased rapidly in the past decade, approaching saturation by middle childhood in developed countries. Besides many ...benefits, online content, contact or conduct can be associated with risk of harm; most research has examined whether aggressive or sexual harms result from this. We examine the nature and prevalence of such risks, and evaluate the evidence regarding the factors that increase or protect against harm resulting from such risks, so as to inform the academic and practitioner knowledge base. We also identify the conceptual and methodological challenges encountered in this relatively new body of research, and highlight the pressing research gaps.
Methods
Given the pace of change in the market for communication technologies, we review research published since 2008. Following a thorough bibliographic search of literature from the key disciplines (psychology, sociology, education, media studies and computing sciences), the review concentrates on recent, high quality empirical studies, contextualizing these within an overview of the field.
Findings
Risks of cyberbullying, contact with strangers, sexual messaging (‘sexting’) and pornography generally affect fewer than one in five adolescents. Prevalence estimates vary according to definition and measurement, but do not appear to be rising substantially with increasing access to mobile and online technologies, possibly because these technologies pose no additional risk to offline behaviour, or because any risks are offset by a commensurate growth in safety awareness and initiatives. While not all online risks result in self‐reported harm, a range of adverse emotional and psychosocial consequences is revealed by longitudinal studies. Useful for identifying which children are more vulnerable than others, evidence reveals several risk factors: personality factors (sensation‐seeking, low self‐esteem, psychological difficulties), social factors (lack of parental support, peer norms) and digital factors (online practices, digital skills, specific online sites).
Conclusions
Mobile and online risks are increasingly intertwined with pre‐existing (offline) risks in children's lives. Research gaps, as well as implications for practitioners, are identified. The challenge is now to examine the relations among different risks, and to build on the risk and protective factors identified to design effective interventions.
Supramolecular materials Amabilino, David B; Smith, David K; Steed, Jonathan W
Chemical Society reviews,
05/2017, Letnik:
46, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Molecular material properties depend upon the contacts between and the arrangement of the component parts, and therefore supramolecular chemistry has developed a highly important role in this area. ...This Tutorial Review, after briefly introducing the history of the field, discusses some of the most exciting and inspiring recent achievements, with special focus on soft materials, particularly gels and liquid crystals.
Molecular material properties depend upon the contacts between and the arrangement of the component parts, and therefore supramolecular chemistry has developed a highly important role in this area.
Gel-phase materials are generated when molecular building blocks assemble into nanoscale architectures, usually 'one-dimensional' fibrils, which hierarchically assemble into bundles and subsequently ...form an entangled sample spanning network, capable of preventing the flow of bulk solvent. This tutorial review explores the vital role of chirality in gel formation. In particular, we focus on how fundamental self-assembly processes can translate molecular scale chiral information into nanoscale architectures, and then into the macroscopic behaviour of the gel. Chiral molecular gels have potential applications in nanofabrication and as addressable functional nanomaterials.
Muscle protein synthesis (MPS) is the driving force behind adaptive responses to exercise and represents a widely adopted proxy for gauging chronic efficacy of acute interventions, (i.e. ...exercise/nutrition). Recent findings in this arena have been progressive. Nutrient‐driven increases in MPS are of finite duration (∼1.5 h), switching off thereafter despite sustained amino acid availability and intramuscular anabolic signalling. Intriguingly, this ‘muscle‐full set‐point’ is delayed by resistance exercise (RE) (i.e. the feeding × exercise combination is ‘more anabolic’ than nutrition alone) even ≥24 h beyond a single exercise bout, casting doubt on the importance of nutrient timing vs. sufficiency per se. Studies manipulating exercise intensity/workload have shown that increases in MPS are negligible with RE at 20–40% but maximal at 70–90% of one‐repetition maximum when workload is matched (according to load × repetition number). However, low‐intensity exercise performed to failure equalises this response. Analysing distinct subcellular fractions (e.g. myofibrillar, sarcoplasmic, mitochondrial) may provide a readout of chronic exercise efficacy in addition to effect size in MPS per se, i.e. while ‘mixed’ MPS increases similarly with endurance and RE, increases in myofibrillar MPS are specific to RE, prophetic of adaptation (i.e. hypertrophy). Finally, the molecular regulation of MPS by exercise and its regulation via ‘anabolic’ hormones (e.g. IGF‐1) has been questioned, leading to discovery of alternative mechanosensing–signalling to MPS.
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