799 research outputs found

    New Methods to Assess Climate Change Impacts, Vulnerability and Adaptation of Agricultural Production Systems: The experience of AgMIP’s Regional Integrated Assessments in Sub-Saharan Africa and South Asia

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    The climate change research community has recognized that new pathway and scenario concepts are needed to implement impact and vulnerability assessment that is logically consistent across global, regional and local scales. The most common challenge is that global models do not provide context-specific answers, while scientists and decision makers require data and information about climate change, vulnerability, adaptation, mitigation and impacts at the local scale. The Agricultural Model Inter-comparison and Improvement Project (AgMIP) provides the link between global climate change projections and sector-specific and regional pathways and scenarios (Antle et al., 2015; Rosenzweig et al., 2013). AgMIP, through a trans-disciplinary process involving both scientists and stakeholders, is developing Representative Agricultural Pathways (RAPs) for agricultural systems at both global and regional scales. In addition to climate modeling, RAPs include bio-physical and socio-economic drivers, associated capabilities, challenges and opportunities. RAPs can then be translated as components of the AgMIP Regional Integrated Assessments (RIA) of climate vulnerability and impacts

    Methods for environment: productivity trade-off analysis in agricultural systems

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    Trade-off analysis has become an increasingly important approach for evaluating system level outcomes of agricultural production and for prioritising and targeting management interventions in multi-functional agricultural landscapes. We review the strengths and weakness of different techniques available for performing trade-off analysis. These techniques, including mathematical programming and participatory approaches, have developed substantially in recent years aided by mathematical advancement, increased computing power, and emerging insights into systems behaviour. The strengths and weaknesses of the different approaches are identified and discussed, and we make suggestions for a tiered approach for situations with different data availability. This chapter is a modified and extended version of Klapwijk et al. (2014)

    Global parameter search reveals design principles of the mammalian circadian clock

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    Background: Virtually all living organisms have evolved a circadian (~24 hour) clock that controls physiological and behavioural processes with exquisite precision throughout the day/night cycle. The suprachiasmatic nucleus (SCN), which generates these ~24 h rhythms in mammals, consists of several thousand neurons. Each neuron contains a gene-regulatory network generating molecular oscillations, and the individual neuron oscillations are synchronised by intercellular coupling, presumably via neurotransmitters. Although this basic mechanism is currently accepted and has been recapitulated in mathematical models, several fundamental questions about the design principles of the SCN remain little understood. For example, a remarkable property of the SCN is that the phase of the SCN rhythm resets rapidly after a 'jet lag' type experiment, i.e. when the light/ dark (LD) cycle is abruptly advanced or delayed by several hours. Results: Here, we describe an extensive parameter optimization of a previously constructed simplified model of the SCN in order to further understand its design principles. By examining the top 50 solutions from the parameter optimization, we show that the neurotransmitters' role in generating the molecular circadian rhythms is extremely important. In addition, we show that when a neurotransmitter drives the rhythm of a system of coupled damped oscillators, it exhibits very robust synchronization and is much more easily entrained to light/dark cycles. We were also able to recreate in our simulations the fast rhythm resetting seen after a 'jet lag' type experiment. Conclusion: Our work shows that a careful exploration of parameter space for even an extremely simplified model of the mammalian clock can reveal unexpected behaviours and non-trivial predictions. Our results suggest that the neurotransmitter feedback loop plays a crucial role in the robustness and phase resetting properties of the mammalian clock, even at the single neuron level

    Disclosure of Maternal HIV Status to Children: To Tell or Not To Tell . . . That Is the Question

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    HIV-infected mothers face the challenging decision of whether to disclose their serostatus to their children. From the perspective of both mother and child, we explored the process of disclosure, providing descriptive information and examining the relationships among disclosure, demographic variables, and child adjustment. Participants were 23 mothers and one of their noninfected children (9 to 16 years of age). Sixty-one percent of mothers disclosed. Consistent with previous research, disclosure was not related to child functioning. However, children sworn to secrecy demonstrated lower social competence and more externalizing problems. Differential disclosure, which occurred in one-third of the families, was associated with higher levels of depressive and anxiety symptoms. Finally, knowing more than mothers had themselves disclosed was related to child maladjustment across multiple domains. Clinical implications and the need for future research are considered

    What can the language of musicians tell us about music interaction design?

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    It is difficult to create good interaction designs for music software or to substantially improve existing designs. One reason is that music involves diverse and complex concepts, entities, relationships, processes, terminologies, and notations. An open challenge for interaction designers is to find systematic ways of channeling the tacit, specialized knowledge of musicians into designs for intuitive user interfaces that can capably support musically skilled users, without excluding those with less technical musical knowledge. One promising new approach to this challenge involves the application of research from the theory of image schemas and conceptual metaphors This theory has already been applied with some success to analyzing musical concepts, mathematical concepts, general-purpose user-interface design, and sound-generation interaction designs involving simple musical parameters such as tempo, volume, and pitch. We propose that by identifying the conceptual metaphors and image schemas used by musical experts when analyzing an excerpt of music, and then assessing the extent to which these conceptual metaphors are supported by existing music-interaction designs, it is possible to identify areas where the designs do not match musicians’ understanding of the domain concepts. This process provides a principled basis for identifying points at which designs could be improved to better support musicians’ understanding and tasks, and for the provisional identification of possible improvements. We present the results of an analysis of dialogue between three musicians as they discuss an excerpt of music. A methodology for the systematic identification of image schemas and conceptual metaphors is detailed. We report on the use of the results of the dialogue analysis to illuminate the designs of two contrasting examples of music software. Areas in which the designs might be made more intuitive are identified, and corresponding suggestions for improvements are outlined. The present research appears to be the first to investigate the potential of conceptual metaphor theory for investigating and improving music-interaction designs that deal with complex musical concepts, such as harmonic progressions, modulation, and voice leading

    Using AgMIP Regional Integrated Assessment Methods to Evaluate Vulnerability, Resilience and Adaptive Capacity for Climate Smart Agricultural Systems

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    The predicted effects of climate change call for a multi-dimensional method to assess the performance of various agricultural systems across economic, environmental and social dimensions. Climate smart agriculture (CSA) recognizes that the three goals of climate adaptation, mitigation and resilience must be integrated into the framework of a sustainable agricultural system. However, current methods to determine a systems’ ability to achieve CSA goals are lacking. This paper presents a new simulation-based method based on the Regional Integrated Assessment (RIA) methods developed by the Agricultural Model Inter-comparison and Improvement Project (AgMIP) for climate impact assessment. This method combines available data, field- and stakeholder-based surveys, biophysical and economic models, and future climate and socio-economic scenarios. It features an integrated farm and household approach and accounts for heterogeneity across biophysical and socioeconomic variables as well as temporal variability of climate indicators. This method allows for assessment of the technologies and practices of an agricultural system to achieve the three goals of CSA. The case study of a mixed crop livestock system in western Zimbabwe is highlighted as a typical smallholder agricultural systems in Africa

    Electrochemical Oxidation and Sensing of Methylamine Gas in Room Temperature Ionic Liquids

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    The electrochemical behaviour of methylamine gas in several room temperature ionic liquids (RTILs), [C2mim][NTf2], [C4mim][NTf2], [C6mim][FAP], [C4mpyrr][NTf2], [C4mim][BF4], and [C4mim][PF6] has been investigated on a Pt microelectrode using cyclic voltammetry. A broad oxidation wave at approximately 3 V, two reduction peaks and another oxidation peak was observed. A complicated mechanism is predicted based on the voltammetry obtained, with ammonia gas as a likely by-product. The currents obtained suggest that methylamine has a high solubility in RTILs, which is important for gas sensing applications. The analytical utility of methylamine was then studied in [C4mpyrr][NTf2] and [C2mim][NTf2]. A linear calibration graph with an R2 value of 0.99 and limits of detection of 33 and 34 ppm were obtained respectively, suggesting that RTILs are favourable non-volatile solvents for the electrochemical detection of highly toxic methylamine gas

    Renegotiation and Relative Performance Evaluation: Why an Informative Signal may be Useless

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    Although Holmström's informativeness criterion provides a theoretical foundation for the controllability principle and inter firm relative performance evaluation, empirical and field studies provide only weak evidence on such practices. This paper refines the traditional informativeness criterion by abandoning the conventional full-commitment assumption. With the possibility of renegotiation, a signal's usefulness in incentive contracting depends on its information quality, not simply on whether the signal is informative. This paper derives conditions for determining when a signal is useless and when it is useful. In particular, these conditions will be met when the signal's information quality is either sufficiently poor or sufficiently rich

    Single Gene Deletions of Orexin, Leptin, Neuropeptide Y, and Ghrelin Do Not Appreciably Alter Food Anticipatory Activity in Mice

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    Timing activity to match resource availability is a widely conserved ability in nature. Scheduled feeding of a limited amount of food induces increased activity prior to feeding time in animals as diverse as fish and rodents. Typically, food anticipatory activity (FAA) involves temporally restricting unlimited food access (RF) to several hours in the middle of the light cycle, which is a time of day when rodents are not normally active. We compared this model to calorie restriction (CR), giving the mice 60% of their normal daily calorie intake at the same time each day. Measurement of body temperature and home cage behaviors suggests that the RF and CR models are very similar but CR has the advantage of a clearly defined food intake and more stable mean body temperature. Using the CR model, we then attempted to verify the published result that orexin deletion diminishes food anticipatory activity (FAA) but observed little to no diminution in the response to CR and, surprisingly, that orexin KO mice are refractory to body weight loss on a CR diet. Next we tested the orexigenic neuropeptide Y (NPY) and ghrelin and the anorexigenic hormone, leptin, using mouse mutants. NPY deletion did not alter the behavior or physiological response to CR. Leptin deletion impaired FAA in terms of some activity measures, such as walking and rearing, but did not substantially diminish hanging behavior preceding feeding time, suggesting that leptin knockout mice do anticipate daily meal time but do not manifest the full spectrum of activities that typify FAA. Ghrelin knockout mice do not have impaired FAA on a CR diet. Collectively, these results suggest that the individual hormones and neuropepetides tested do not regulate FAA by acting individually but this does not rule out the possibility of their concerted action in mediating FAA
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