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A consensus workshop on low-calorie sweeteners (LCS) was held in November 2018 where seventeen experts (the panel) discussed three themes identified as key to the science and policy of LCS: (1) weight management and glucose control; (2) consumption, safety and perception; (3) nutrition policy. The aims were to identify the reliable facts on LCS, suggest research gaps and propose future actions. The panel agreed that the safety of LCS is demonstrated by a substantial body of evidence reviewed by regulatory experts and current levels of consumption, even for high users, are within agreed safety margins. However, better risk communication is needed. More emphasis is required on the role of LCS in helping individuals reduce their sugar and energy intake, which is a public health priority. Based on reviews of clinical evidence to date, the panel concluded that LCS can be beneficial for weight management when they are used to replace sugar in products consumed in the diet (without energy substitution). The available evidence suggests no grounds for concerns about adverse effects of LCS on sweet preference, appetite or glucose control; indeed, LCS may improve diabetic control and dietary compliance. Regarding effects on the human gut microbiota, data are limited and do not provide adequate evidence that LCS affect gut health at doses relevant to human use. The panel identified research priorities, including collation of the totality of evidence on LCS and body weight control, monitoring and modelling of LCS intakes, impacts on sugar reduction and diet quality and developing effective communication strategies to foster informed choice. There is also a need to reconcile policy discrepancies between organisations and reduce regulatory hurdles that impede low-energy product development and reformulation.
The quality of prenatal maternal mental health, from psychological stress and depressive symptoms to anxiety and other nonpsychotic mental disorders, profoundly affects fetal neurodevelopment. Despite the evidence for the influence of positive mental well-being on health, there is, to our knowledge, no research examining the possible effects of positive antenatal mental health on the development of the offspring. Using exploratory bifactor analysis, this prospective study (n = 1,066) demonstrated the feasibility of using common psychiatric screening tools to examine the effect of positive maternal mental health. Antenatal mental health was assessed during 26th week of pregnancy. The effects on offspring were assessed when the child was 12, 18, and 24 months old. Results showed that positive antenatal mental health was uniquely associated with the offspring's cognitive, language and parentally rated competences. This study shows that the effects of positive maternal mental health are likely to be specific and distinct from the sheer absence of symptoms of depression or anxiety.
We consider a single-item, two-echelon spare parts inventory model for repairable parts for capital goods with high downtime costs. The inventory system consists of multiple local warehouses, a central warehouse, and a central repair facility. When a part at a customer fails, if possible his request for a ready-for-use part is fulfilled by his local warehouse. Also, the failed part is sent to the central repair facility for repair. If the local warehouse is out of stock, then, via an emergency shipment, a ready-for-use part is sent from the central warehouse if it has a part in stock. Otherwise, it is sent via a lateral transshipment from another local warehouse, or via an emergency shipment from the external supplier. We assume Poisson demand processes, generally distributed leadtimes for replenishments, repairs, and emergency shipments, and a basestock policy for the inventory control.
Our inventory system is too complex to solve for a steady-state distribution in closed form. We approximate it by a network of Erlang loss queues with hierarchical jump-over blocking. We show that this network has a product-form steady-state distribution. This enables an efficient heuristic for the optimization of basestock levels, resulting in good approximations of the optimal costs.
Human milk contains bioactive compounds that confer a protective role against gastrointestinal infections. In order to find supplements for an infant formula able to mimic these benefits of breast-feeding, two different concepts were tested. The products consisted of the following: (1) a Bifidobacterium breve- and Streptococcus thermophilus-fermented formula and (2) a combination of short-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides with pectin-derived acidic oligosaccharides. A rotavirus infection suckling rat model was used to evaluate improvements in the infectious process and in the immune response of supplemented animals. Both nutritional concepts caused amelioration of the clinical symptoms, even though this was sometimes hidden by softer stool consistency in the supplemented groups. Both products also showed certain modulation of immune response, which seemed to be enhanced earlier and was accompanied by a faster resolution of the process. The viral shedding and the in vitro blocking assay suggest that these products are able to bind the viral particles, which can result in a milder infection. In conclusion, both concepts evaluated in this study showed interesting protective properties against rotavirus infection, which deserve to be investigated further.
Rapid climatic and socio-economic changes challenge current agricultural R&D capacity. The necessary quantum leap in knowledge generation should build on the innovation capacity of farmers themselves. A novel citizen science methodology, triadic comparisons of technologies or tricot, was implemented in pilot studies in India, East Africa, and Central America. The methodology involves distributing a pool of agricultural technologies in different combinations of three to individual farmers who observe these technologies under farm conditions and compare their performance. Since the combinations of three technologies overlap, statistical methods can piece together the overall performance ranking of the complete pool of technologies. The tricot approach affords wide scaling, as the distribution of trial packages and instruction sessions is relatively easy to execute, farmers do not need to be organized in collaborative groups, and feedback is easy to collect, even by phone. The tricot approach provides interpretable, meaningful results and was widely accepted by farmers. The methodology underwent improvement in data input formats. A number of methodological issues remain: integrating environmental analysis, capturing gender-specific differences, stimulating farmers' motivation, and supporting implementation with an integrated digital platform. Future studies should apply the tricot approach to a wider range of technologies, quantify its potential contribution to climate adaptation, and embed the approach in appropriate institutions and business models, empowering participants and democratizing science.
Health nudge interventions to steer people into healthier lifestyles are increasingly applied by governments worldwide, and it is natural to look to such approaches to improve health by altering what people choose to eat. However, to produce policy recommendations that are likely to be effective, we need to be able to make valid predictions about the consequences of proposed interventions, and for this, we need a better understanding of the determinants of food choice. These determinants include dietary components (e.g. highly palatable foods and alcohol), but also diverse cultural and social pressures, cognitive-affective factors (perceived stress, health attitude, anxiety and depression), and familial, genetic and epigenetic influences on personality characteristics. In addition, our choices are influenced by an array of physiological mechanisms, including signals to the brain from the gastrointestinal tract and adipose tissue, which affect not only our hunger and satiety but also our motivation to eat particular nutrients, and the reward we experience from eating. Thus, to develop the evidence base necessary for effective policies, we need to build bridges across different levels of knowledge and understanding. This requires experimental models that can fill in the gaps in our understanding that are needed to inform policy, translational models that connect mechanistic understanding from laboratory studies to the real life human condition, and formal models that encapsulate scientific knowledge from diverse disciplines, and which embed understanding in a way that enables policy-relevant predictions to be made. Here we review recent developments in these areas.
The large body of literature on the association between blood pressure (BP) and cognitive functioning has yielded mixed results, possibly due to the presence of non-linear effects across age, or because BP affects specific brain areas differently, impacting more on some cognitive skills than on others. If a robust association was detected among BP and specific cognitive tasks, the causal nature of reported associations between BP and cognition could be investigated in twin data, which allow a test of alternative explanations, including genetic pleiotropy. The present study first examines the association between BP and cognition in a sample of 1,140 participants with an age range between 10 and 86 years. Linear and quadratic effects of systolic BP (SBP) and diastolic BP (DBP) on cognitive functioning were examined for 17 tests across five functions. Associations were corrected for effects of sex and linear and quadratic effects of age. Second, to test a causal model, data from 123 monozygotic (MZ) twin pairs were analyzed to test whether cognitive functioning of the twins with the higher BP was different from that of the co-twins with lower BP. Associations between BP and cognitive functioning were absent for the majority of the cognitive tests, with the exception of a lower speed of emotion identification and verbal reasoning in subjects with high diastolic BP. In the MZ twin pair analyses, no effects of BP on cognition were found. We conclude that in the population at large, BP level is not associated with cognitive functioning in a clinically meaningful way.
We introduce the main characteristics of the chemistry system in the ABL. As with the dynamics, we explain the equations that govern the evolution of chemical species, emphasizing in particular their physical and chemical contributions to the diurnal variability of the reactive species, and providing a framework to understand and quantify how dynamic processes interact with the atmospheric reactivity.
Several hundreds of species and reactions characterize the chemistry of the atmospheric boundary layer. As a buffer layer between the surface and the free troposphere, the ABL integrates the emission of chemically active species driven by soil processes or vegetation dynamics as well as their removal by dry and wet deposition processes. Within the dynamically evolving ABL upper region, air entrainment introduces air masses that may either enrich or dilute the chemically reactive species. The presence of ultraviolet radiation and turbulent mixing produces the right conditions for chemical transformations, turning the ABL into a dynamic reaction chamber in which secondary compounds are produced.
A useful method to classify the reactants is to relate them to the dynamic processes by defining the characteristic time-scales of reactions. Figure 3.1 shows some of the most relevant atmospheric components that are active in the lower troposphere. The diagram classifies them as a function of their characteristic reaction speeds and their horizontal spatial variability. This enables us to identify very rapid reactive species (radicals) whose time-scales are similar to those of the fast turbulent motions (<100 s). Particular attention should be paid to the hydroxyl radical (OH) because of its prominent role in oxidizing important hydrocarbon compounds such as methane (CH4), carbon monoxide (CO), and isoprene (C5H8). OH is therefore called the ‘atmospheric cleansing’ agent.
Important species such as O3 and isoprene react on a chemistry time-scale that is similar to the turbulent mixing under diurnal conditions (τ ≈ 15–30 minutes).
Buffering the free atmospheric conditions from the soil-vegetation properties, the atmospheric boundary layer (ABL) is the region in which the wind, temperature, moisture, and atmospheric constituents change from the large atmospheric scales to the biosphere conditions. Over land, the ABL is characterized by a strong diurnal variability (daylight hours) that presents a challenge to modelling studies and observational interpretation. The first purpose of this book is to introduce the reader systematically to the most important biogeochemical and physical processes that take place in the ABL. A flexible user-friendly model of these processes called Chemistry Land-surface Atmosphere Soil Slab (CLASS) was developed to enable the reader interactively and independently to investigate the behaviour of the diurnal ABL over land. Our second aim is to enable the reader to discover freely the interactions and couplings that occur between the atmosphere and land, and to determine their impact on cloud formation, changes in greenhouse gas concentrations, and atmospheric chemistry. To this end, we decided to represent the main fundamental processes in the atmosphere-biosphere system, while retaining the essential components of the physical and biogeochemical processes involved. We have therefore attempted to move beyond individual disciplines to investigate their mutual interrelationships and feedback, laying special emphasis on the conceptualization of the problem. Finally, the interactivity and modular character of the book will make it very useful as a means of interpreting measurements made during experimental campaigns and deepening our understanding of more complex large-scale biogeochemical atmospheric models.
The introduction of a representation of the dynamics of plants and soil (Chapter 11) enables us to study the fully coupled atmosphere-vegetation-soil system. As a result, however, we are now confronted by a system that is characterized by many degrees of freedom. Our existing knowledge, acquired by analysing heat, moisture, and momentum budgets, is now extended to determine how the carbon dioxide budget influences the thermodynamics and whether modifications of the heat and moisture budgets result in changes of CO2. The CO2 budget decoupled from the soil and vegetation processes was already introduced in Chapter 7.
At this point, we can take two different paths: to investigate the budgets and their interaction on the diurnal time-scale (as in previous chapters), or devote our analysis to determine how modifications in a process or variable lead to changes in the other variables. In taking the second path, we focus on a systematic analysis in order to answer the following questions: (a) How do ‘potential’ variations of the atmosphere, vegetation, and soil conditions influence the exchange of carbon dioxide and water vapour at the surface and the subsequent implications on the ABL? (b) What is the impact of these variations on the thermodynamic and carbon dioxide budgets?
Since we are now dealing with a complex system characterized by several interacting variables, we limit ourself to key long-term modifications (climate) that can affect the carbon and water cycle. We therefore adopt a larger climate perspective in formulating the research questions to be studied employing CLASS. In so doing, we define various scenarios with warmer mean temperatures, drought conditions, higher CO2 concentration levels, and global radiation dimming. We are then able to study the relevance, impact, and changes of the couplings and feedbacks among the various components of the atmosphere-land system due to changes of the large-scale (climate) forcing. We therefore assume that the time-scale of the ABL dynamics defined by the turbulent mixing is very short compared to the time-scale of the changes in the large-scale system (for instance, changes in the synoptic flow patterns or soil moisture modifications due to perturbed rainfall patterns).