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Modeling of irrigation and related processes with HYDRUS
No full textFuture agriculture calls for increased input (e.g., water, nutrients, pesticides) use efficiency while maintaining or improving productivity, minimizing environmental impacts, and increasing profitability. Complete understanding of complex irrigation systems requires laborious, time-consuming, and expensive field investigations, which invariably involve only a limited number of treatments. On the other hand, fully calibrated process-based models, such as HYDRUS, can quickly evaluate different irrigation management strategies without the need for labor-intensive fieldwork and have become valuable research tools for predicting complex and interactive water flow and solute transport processes in and below the root zone. HYDRUS codes have been used worldwide in several hundreds of studies evaluating various types of irrigation (e.g., sprinkler, furrow, basin, and surface and subsurface drip), their scheduling (e.g., the timing of irrigation and its amount), and solute-related factors (e.g., fertigation, chemigation, salinization, and sodification). The objective of this manuscript is to review the current modeling capabilities of HYDRUS to evaluate various irrigation methods and related processes. The manuscript starts with a section describing governing flow and transport equations solved numerically by the HYDRUS codes, the corresponding initial and boundary conditions, and related factors such as soil hydraulic properties and root water and nutrient uptake. Modeling of different irrigation techniques is described in subsequent sections, followed by sections dealing with solute-related topics such as fertigation, chemigation, and salinization/sodification. Topics, including the effects of spatial variability, optimization of irrigation systems, and special irrigation methods, are covered in the later sections. The manuscript emphasizes the advantages and opportunities of HYDRUS in describing various processes in the root zone of irrigated plants that support sustainable irrigated agriculture. All the project files of the discussed examples and their descriptions are available for download at https://www.pc-progress.com/en/Default.aspx?hyd5-AdvancesInAgronomy
Working hours and job satisfaction in China: A threshold analysis
No full textThis study utilizes a threshold model to examine the nonlinear relationship between working hours and job satisfaction, using the open-access data of the 2018 China Family Panel Studies. We address the endogeneity of working hours utilizing an instrumental variable-based two-stage residual inclusion approach. The threshold model shows that the effects are indeed different. Working more than 9 h reduces workers' job satisfaction, and these reductions are even greater among those working more than 12 h. Heterogeneous analysis reveals that working long hours reduces the job satisfaction of female employees more than that of their male counterparts; the job satisfaction of unmarried individuals is unaffected by how long they work, whereas that of married workers declines when they work longer hours. Also, although the job satisfaction of wage-employed workers falls with an increase in the number of hours worked regardless of how long they work, that of self-employed workers falls only when they work more than 12 h. Poor physical health mediates the adverse effects of long working hours on job satisfaction. Finally, working long hours reduces individuals' short-run hedonic well-being but does not affect their perceptions and feelings towards various facets of life in the long run
Exploring the textural dynamics of dairy and plant-based yoghurts: A comprehensive study
No full textThe mouthfeel and texture of dairy and non-dairy yoghurts play a critical role in food acceptance and liking. The present study aimed to understand the oral perception of commercially available dairy and non-dairy yoghurts. Four dairy and four non-dairy yoghurts with different levels of protein and fat were analyzed to understand the impact of particle size, textural properties and frictional coefficient on the dynamic sensory mouthfeel characteristics measured by the temporal dominance of sensations (TDS) method. Differences in friction coefficients of dairy and non-dairy yoghurts were observed. The friction factor was lower for high-fat dairy yoghurts than for non-dairy yoghurts. The particle size d₉₀ in yoghurts was positively related to graininess perception (r=0.81) and negatively associated with mouthfeel liking (r=0.87) and overall liking (r=0.80). For the TDS results, “creaminess” and “thickness” were significantly dominant for dairy yoghurts, while “melty” and “easy to dissolve” were dominant attributes for non-dairy yoghurts. Creaminess perception improves the mouthfeel liking (r=0.72) and overall liking (r=0.59) of yoghurts and is the driver of liking. The findings of this study help understand the intrinsic mouthfeel properties of commercial dairy and non-dairy yoghurts, which will provide valuable insight to product developers during the new product formulation
Third-generation adaptive capacity assessment for climate-resilient development
No full textHuman development seeks to enlarge freedoms by building capacity and is integral to achieving sustainable development, particularly in the era of the Anthropocene. However, the efficiency and effectiveness of capacity building is limited. First-generation adaptive capacity emphasizes a deficit model. Second-generation adaptive capacity focuses on mobilization by individuals. Neither adequately address the issue of scale, nor recognize how stocks of capacity are enhanced or diminished through interactions between individuals and groups. Addressing these shortcomings and realizing climate-resilient development, is contingent upon a next (third) generation of adaptive capacity that incorporates the transfer of capacity
Estimating the temperature optima of soil priming
No full textUnderstanding the temperature response of soil microbial respiration is essential for predicting carbon (C) losses as the planet warms. As fresh, labile C inputs can further accelerate soil C loss (priming effect), determining if priming is temperature sensitive has important implications for global C cycling and remains relatively unexplored. We conducted a series of 5-h incubations for five different soil orders at 40 discrete temperatures with added ¹³C-labelled glucose and measured soil microbial respiration. We then estimated the temperature response of microbial respiration attributable to (1) the added glucose, (2) the soil organic matter (SOM), and (3) soil priming. The relative proportion of the priming response varied with temperature and the magnitude of these changes differed by soil type. We found that the temperature response of microbial respiration attributable to priming and to the added glucose were unimodal and could be modelled using Macromolecular Rate Theory (MMRT). This suggests that biological mechanisms play a strong role in shaping the temperature response of priming. In contrast, respiration derived from SOM typically increased continuously with increasing temperature. Using MMRT we estimated a temperature optimum (Topt) and inflection point (Tinf) from each of the temperature response curves for microbial respiration derived from the added glucose and from soil priming. The temperature response of respiration from soil priming (Topt = 30.6 ºC and Tinf = 12.8 ºC) was significantly lower than from the added glucose (Topt = 42.4 ºC and Tinf = 14.5 ºC), which indicates that priming is more temperature sensitive. This study demonstrates that soil priming itself is temperature sensitive and responds differently to warming than the bulk soil, which may alter soil C stocks in ways not previously predicted. Further exploration of the temperature sensitivity of priming therefore warrants inclusion in future discussions of soil microbial responses to climate change
Designing grazing systems that enhance the health of New Zealand high-country grasslands : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University
Get PDFGrazing management enabling pastoral livestock-production systems to deliver multiple ecosystem services is key to assure the long-term health and stability of grasslands. In the context of designing multi-functional grazing systems to enhance grassland health, systems thinking emerges as a useful tool to understand, modulate and enhance the resilience of those systems. The objective of the outlined research was to apply systems thinking and design theory to design alternative grazing systems that enhance grassland health using high-country stations in New Zealand as a model and Lincoln University Mount Grand Station (LUMGS) as the case study. This was conducted over five modelling exercises described as the design method to design scenarios representing distinct grazing management that enhance grassland health in different ways. The first design step applied spatial analysis to create a modern rich picture for grassland health diagnostic which determined that 97.7% of LUMGS grassland has a moderate health condition. Then, a geospatial modelling approach was used to assess the current capability of LUMGS in delivering ecosystem services. It was determined that LUMGS has a spatially variable potential for agriculture productivity, a high flood mitigation capacity, a high capacity of C sequestration, an extreme risk of erosion, a capacity to reduce sediment delivery to streams, and overall, a low to moderate nitrogen and phosphorus accumulation. Those ecosystem services were negatively affected by farming activities. Next, a geospatial modelling approach was used to understand the spatiotemporal impacts of different stock densities, grazing occupation periods, and stock types on soil susceptibility to erosion. Increases in the occupation period were more detrimental to soil loss than increases in stock density, and losses were greater for cattle than for sheep and deer. Those effects were spatially and temporally variable. In the following chapter, we applied a spatial-chemical analysis to grassland ecosystems for the illustration of chemoscapes and the creation of healthscapes. We created maps that show an extra perspective of plant nutritional value by illustrating their distribution over LUMGS according to their medicinal effects. Finally, by integrating all those design tools, three alternative grazing system scenarios were created and evaluated, from which a multi-criteria evaluation defined that the ‘best-compromise’ scenario to enhance grassland health is the scenario with lower soil erosion, the lower total emission of greenhouse gases, and greater profitability compared to the parsimonious approach of the ‘status quo’. The design methodology proposed in this thesis demonstrates that grasslands need to be managed as context-adjusted, adaptive, and complex systems to be multifunctional and continually deliver multiple ecosystem services to enhance grassland health
Does income diversity really stimulate household consumption expenditure diversity? Evidence from mean-based and unconditional quantile regressions
No full textAlthough both income diversity and household consumption expenditure diversity are positively correlated with income, little is known about how the former affects the latter. This study investigates how and to what extent income diversity stimulates household consumption expenditure diversity, utilizing data collected by the China Social Survey. We estimate a standard mean-based linear regression model and an unconditional quantile regression (UQR) model to explore mean-based and quantile-specific effects, respectively. The results of the linear regression show that income diversity significantly increases household consumption expenditure diversity. The UQR estimates provide more granular insights, revealing that income diversity improves consumption expenditure diversity at the lower quantiles (5th and 25th), with the largest effect occurring at the lowest 5th quantile; for the higher quantiles, income diversity has no effect on consumption expenditure diversity. Our findings highlight that policies aimed at improving consumption expenditure diversity and the quality of life of people in China should create an economic environment that allows people to diversify their income sources. From a methodological standpoint, we show that mean-based approaches may overlook the finer details of the linkages between income and consumption and thus should be applied cautiously
Demonstration of a negative-refractive-index lens imaging system
No full textAn imaging system comprising a planar negative-refractive-index lens and a pair of small loop antennas is described. The two loops antennas are fixed on one side of the lens, and the object is transversely scanned across the other side. One loop illuminates the object through the lens. Reflection from the object is focused by the lens onto a plane containing the other loop. This loop senses both reflected and incident fields. An image is constructed by relating transmission (S21) between the loops to the object translation. The system was demonstrated experimentally at 3 GHz and supported by theory
Partial least squares regression with multiple domains
No full textThis paper introduces the multiple domain-invariant partial least squares (mdi-PLS) method, which generalizes the recently introduced domain-invariant partial least squares method (di-PLS). In contrast to di-PLS which solely allows transferring of knowledge from a single source to a single target domain, the proposed approach enables the incorporation of data from an arbitrary number of domains. Additionally, mdi-PLS offers a high level of flexibility by accepting labeled (supervised) and unlabeled (unsupervised) data to cope with dataset shifts. We demonstrate the application of the mdi-PLS method on a simulated and one real-world dataset. Our results show a clear outperformance of both PLS and di-PLS when data from multiple related domains are available for training multivariate calibration models underpinning the benefit of mdi-PLS
Model-free connectedness measures
No full textThis paper introduces a model-free connectedness approach by constraining the model-based connectedness approach of Diebold and Yilmaz (2012). By doing so, we demonstrate how the adoption of this benchmark model is relevant for statistical, theoretical, and practical purposes as well as illuminate analytical relations that have previously been observed only empirically. Moreover, we investigate eight publicly available connectedness datasets and illustrate the differences between model-free and model-based connectedness measures. Finally, robust unconditional connectedness measures are provided