Non-monotonic Pattern Research Articles

Physiochemical View of Fuel Jet Impingement and Ignition Upon Contact with a Cylindrical Hot Surface

This study delves into ignition and flame dynamics involving a cylindrical hot surface impact. Previous studies have focused on the flat-wall hot surface interacting with fuel spray, leaving gaps in understanding the effects of cylindrical hot surfaces on fuel-air mixing and ignition. Using high-fidelity large-eddy simulations (LES), this study investigates how fluid elements, upon contacting an electronically activated glow plug structure, exhibit mixing and thermochemical properties. The analysis examines how this type of structure enhances fuel-air mixing and subsequently influences the thermochemistry behavior in conjunction with the fuel-specific combustion behavior. The study includes scenarios with free spray and non-thermal deposit cases to assess their mixing impact, alongside testing five different electric voltage inputs to study the thermally assisted ignition process. Results demonstrate that the cylindrical structure hinders flow, reducing its inertia and increasing flow residence time. Moreover, a significant Coandă effect due to the circular wall structure is identified, potentially serving as a mechanism for enhancing flame-holding. Furthermore, varying the input voltage notably affects ignition timing, revealing a non-monotonic ignition delay pattern with lower voltages. Detailed analysis highlights the critical role of negative temperature coefficient (NTC)-driven low-temperature chemistry (LTC) in the ignition process.

Embryonal exposure to 4-methylbenzylidene camphor induces reproduction impairment in adult zebrafish (Danio rerio)

This study investigated how early exposure to xenobiotics can lead to disease in adulthood, which is challenging for toxicologists. We employed a ‘cradle to grave’ approach using zebrafish (Danio rerio) embryos exposed to 4-methylbenzylidene camphor (4-MBC), a commonly used organic UV filter. Molecular docking and simulation studies confirmed the predictive toxicity and stable interaction of 4-MBC with androgen and estrogen receptors, with binding energies of −9.28 and −9.01 kcal/mol, respectively. Exposure to 4-MBC at 5, 50, and 500 μg/L concentrations resulted in significantly altered transcriptional and translational responses of ar, esr1, and vtg1 genes in embryos at 120 h post-fertilization (hpf). The exposure induced a non-monotonic dose-response pattern (NMDR), a characteristic feature of endocrine-disrupting chemicals. Additionally, a significant decrease in fertilization was observed in adults. Although fecundity was not affected in inter- and intra-breeding performances, developmental deformities were observed in F1 progenies with impaired survival at 10 days post-fertilization. The findings of this study show that embryonic exposure to 4-MBC is likely to induce reproductive and transgenerational toxicity in D. rerio and exhibit endocrine disruption in aquatic non-target organisms. This work is the first to elucidate the low-level long-term effects of 4-MBC from the embryonic stage to adulthood.

Range shifts and non-monotonic clines in studies of Bergmann’s rule as applied to climate change

Abstract Bergmann’s rule states that organisms should be smaller in warmer climates. This traditionally implied warmer latitudes, but also applies to warmer eras, as forming due to climate change. Integrating spatial and temporal ecology (chronoecogeography) can help us understand and predict how different species respond to environmental changes over time. However, study results can be misinterpreted if researchers do not take steps in the data collection or analysis stages to account for range shifting or non-monotonic patterns. Multiple variables can cause an organism’s geographic and recent temporal size clines to differ significantly, as seen in a review in this article, and these cannot easily be modeled. Range shifting can affect Bergmann’s rule modeling, especially regarding effects from climate change, and this article suggests methods to account for this when incorporating the dimension of time into climate change-focused ecogeographic research.

Experimental study on multi-point ignition of NH3/air by high-frequency nanosecond dielectric barrier discharge

Non-equilibrium plasma ignition technology, with its ability to expand ignition limits and increase ignition volume, is considered an important development direction of advanced ignition systems, and has significant advantages in improving ignition stability and combustion rate. This study investigates the ignition and combustion assistance effect of high-frequency nanosecond surface dielectric barrier discharge (nSDBD) on NH3/air mixture in a constant volume combustion chamber (CVCC). The study reveals the influence of high-frequency nSDBD on the growth process of the flame kernel in NH3/air mixture. As the discharge pulse number (PN) increases, the flame kernel develops from the middle position of the discharge filament to the head of the discharge filament, while there is no obvious flame at the root and middle of the discharge filament. Continuous discharge causes the flame kernel to appear concave and the center of the flame kernel to shift towards the wall of the CVCC. In the NH3/air mixture, the initial flame kernels exhibit dissipation phenomenon, resulting in a discrepancy between the number of initial flame kernels and the number of stable combustion flame kernels. As the discharge frequency or pulse number increases, and the number of stable combustion flame kernel increases. The adjustment of discharge frequency and pulse number can effectively control the flame development time (FDT) and flame rise time (FRT) of NH3/air mixture. As PN increases, both FDT and FRT are shortened. When discharge frequency is 20 kHz, the maximum shortening of FDT and FRT are 30 ms and 14 ms, respectively, about 55 % and 30 %. The effects of discharge frequency on FDT and FRT exhibit a non-monotonic variation pattern, and it is necessary to comprehensively consider various discharge parameters to achieve the best ignition effect. The ignition success rate curve of high-frequency nSDBD in NH3/air mixture is steep. The study results of this paper provide new discoveries and experimental data for advanced ignition systems.

Effects of Remolding Water Content and Compaction Degree on the Dynamic Behavior of Compacted Clay Soils

The stable and safe operation of highway/railway lines is largely dependent on the dynamic behavior of subgrade fillings. Clay soils are widely used in subgrade construction and are compacted at different remolding water contents and compaction degrees, depending on the field conditions. As a result, their dynamic behaviors may vary, which have not been fully investigated until now. To clarify this aspect, a series of cyclic triaxial tests were carried out in this study with three typical remolding water contents (w = 19%, 24%, and 29%), corresponding to the optimum water content as well as its dry and wet sides, and two compaction degrees (Dc = 0.8 and 0.9), which were selected according to the field-testing data. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests were also conducted on typical samples to investigate the corresponding soil fabric variations. The findings indicate the following: (a) The soil fabric at the optimum remolding water content and its dry side was characterized by a clay aggregate assembly with a bimodal pore size distribution. In contrast, the soil fabric on the wet side of the optimum water content consisted of dispersed clay particles with a unimodal pore size distribution. (b) As the compaction degree increased, to ensure the optimum water content and its dry side, large pores were compressed to make them smaller, while small pores remained unchanged. Comparatively, all the pores on the wet side were compressed to make them smaller. (c) For each compaction degree, as the remolding water content increased, a non-monotonic changing pattern was identified for both the permanent strain and resilient modulus; the permanent strain first decreased and then increased, while, for the resilient modulus, an initial increasing trend and then a decreasing trend were identified. In addition, a larger changing rate of the permanent strain (resilient modulus) was observed on the dry side, indicating a larger effect of the remolding water content. (d) For each remolding water content, as the compaction degree increased, the permanent strain exhibited a decreasing trend, but an increasing trend was identified for the resilient modulus. Moreover, the rate of change in the permanent strain (resilient modulus) on the dry side of the optimum water content was larger than that on the wet side. In contrast, the minimum rate of change was identified at the optimum water content. The obtained results allowed for the effects of the remolding water content and compaction degree on the dynamic behavior to be analyzed, and they helped guide the construction and maintenance of the subgrade.

Phase Separation and Aggregation of α-Synuclein Diverge at Different Salt Conditions.

The coacervation of alpha-synuclein (αSyn) into cytotoxic oligomers and amyloid fibrils are considered pathological hallmarks of Parkinson's disease. While aggregation is central to amyloid diseases, liquid-liquid phase separation (LLPS) and its interplay with aggregation have gained increasing interest. Previous work shows that factors promoting or inhibiting aggregation have similar effects on LLPS. This study provides a detailed scanning of a wide range of parameters, including protein, salt and crowding concentrations at multiple pH values, revealing different salt dependencies of aggregation and LLPS. The influence of salt on aggregation under crowding conditions follows a non-monotonic pattern, showing increased effects at medium salt concentrations. This behavior can be elucidated through a combination of electrostatic screening and salting-out effects on the intramolecular interactions between the N-terminal and C-terminal regions of αSyn. By contrast, this study finds a monotonic salt dependence of LLPS due to intermolecular interactions. Furthermore, it observes time evolution of the two distinct assembly states, with macroscopic fibrillar-like bundles initially forming at medium salt concentration but subsequently converting into droplets after prolonged incubation. The droplet state is therefore capable of inhibiting aggregation or even dissolving aggregates through heterotypic interactions, thus preventing αSyn from its dynamically arrested state.

Cannabidiol Bioavailability Is Nonmonotonic with a Long Terminal Elimination Half-Life: A Pharmacokinetic Modeling-Based Analysis.

Background: Oral and inhalation-based cannabidiol (CBD) administration has been clinically evaluated for various therapeutic indications, alongside widespread off-label use. However, the long-term exposure kinetics and varied bioavailability have not been fully characterized. Methods: Human CBD plasma concentration-time profiles from six studies evaluating the oral administration of Epidiolex® and three studies evaluating inhalation-based delivery were obtained. A four-compartment pharmacokinetic (PK) model with Weibull-based oral absorption kinetics was employed to describe the long-term PKs of CBD. Furthermore, a Cedergreen-Ritz-Streibig model was applied to evaluate nonmonotonic oral bioavailability. Results: CBD was extensively distributed into tissue compartments with varied kinetics resulting in a long plasma terminal elimination half-life of >134 h in humans. For once-a-day oral dosing, the plasma trough concentrations require >70 days to reach a steady state. The oral bioavailability of CBD for different doses administered in fasted state follows a nonmonotonic pattern with an inverted U-shaped profile. Oral administration of CBD under fed state or subjects with hepatic impairment yields higher oral bioavailability with varied exposure. In contrast, inhalation-based delivery of CBD, while delivering a similar systemic delivered dose compared with oral dosing due to high device losses, bypasses first-pass metabolism and can be efficient. Conclusion: CBD PKs vary across different doses due to nonmonotonic oral bioavailability, and inhalation-based delivery could minimize such variability in humans. The delayed attainment of steady state and prolonged terminal half-life, resulting from differential but extensive tissue distribution, needs to be considered when dosing CBD in the long term. These fundamental findings are critical for establishing dose-exposure relationship for further clinical evaluation of novel CBD-based therapies.

Properties of the Household Food Security Survey Module Scale in Young Adults with Diabetes

BackgroundThe Household Food Security Survey Module (HFSSM) was not tailored to people with chronic diseases or young adults (YAs). ObjectivesWe aim to evaluate whether the 18-item HFSSM meets assumptions underlying the scale among YAs with diabetes. MethodsData from 1887 YAs with youth-onset type 1 diabetes or type 2 diabetes were used from the SEARCH for Diabetes in Youth Study, 2016–2019, and on 925 who returned for the SEARCH Food Security Cohort Study, 2018–2021, all of whom had completed the HFSSM. Guttman scaling properties (affirmation of preceding less severe items) and Rasch model properties (probability to answer an item based on difficulty level) were assessed. ResultsItems 3 (balanced meals) and 6 (eating less than one should) were affirmed more frequently than expected (nonmonotonic response pattern). At 1.2%–3.5%, item nonresponse was rare among type 1 diabetes but higher among type 2 diabetes (range: 3.1%–10.6%). Items 9 (not eating the whole day) and 3 did not meet the Guttman scaling properties. Rasch modeling revealed that item 3 had the smallest difficulty parameter. INFIT indices suggested that some responses to item 3 did not match the pattern in the rest of the sample. Classifying household food insecurity (HFI) based on items 1 and 2 compared with other 2-item combinations, including item 3, revealed a substantial undercount of HFI ranging from 5% to 8% points. ConclusionsUse of the HFSSM among YAs with diabetes could potentially result in biased HFI reporting and affect estimates of HFI prevalence in this population.

Effect of patient and diagnostic intervals on the risk of advanced stage in Indian patients with seven types of gastrointestinal cancers: A retrospective cohort study

ObjectivesAdvanced stage is linked to prolonged patient and diagnostic interval for gastrointestinal (GI) cancers. However, objective evidence of this fact is not so forthcoming. Our aim was to study the effect of these intervals on the risk of advanced stage for GI cancers. MethodsWe performed this retrospective cohort study to analyse the effect of patient and diagnostic intervals on final stage in seven types of GI cancers, during 2013 and 2022. Two groups of stage: early (TNM- 0, I, II) and advanced (TNM- III, IV), were formed. Outcome studied was interdependence between patient and diagnostic intervals and incidence of advanced stage. Binary logistic regression was applied to calculate odds ratio of having an advanced versus early stage as a function of duration of these delays, in the whole cohort.We used restricted cubic splines with five knots to study flexible and non-monotonic pattern of association between these delays and stage. ResultsIn whole cohort of 1859 patients, median patient and diagnostic intervals of early and advanced cancers were 21 and 26 days and 120 and 45 days, respectively. There was a positive association between patient interval and advanced stage (odds ratio [OR], 1.04, confidence interval [CI], 1.035 to 1.045; P < 0.001) and negative association between diagnostic interval and advanced stage (odds ratio, 0.98, CI, 0.976 to 0.998; P-0.017), among all gastrointestinal cancers combined. Increased risk of advanced stage started from day one of patient interval and for diagnostic interval there was an initial decrease followed by subsequent increase in the risk of advanced stage beyond 26 days of diagnostic interval. ConclusionsLonger patient and diagnostic intervals increase the risk of advanced stage in gastrointestinal cancers.

The impacts of spatial–temporal heterogeneity of human-to-human contacts on the extinction probability of infectious disease from branching process model

In this study, we focus on the impacts of spatial–temporal heterogeneity of human-to-human contacts on the spread of infectious diseases and develop a multi-type branching process model by introducing random human-to-human contact mode into a structured population. We provide the general formulas of the generation size, extinction probability, and basic reproduction number of the proposed branching process model. The result shows that the natural temporal heterogeneity (i.e. random contacts over time) can lead to a higher extinction probability while remains the same basic reproduction number and generation size. This is also numerically verified by choosing the real contact distributions from different circumstances of four countries. In addition, we observe a non-monotonic pattern of the differences, against the transmission probability and the mean contact rate, between the extinction probabilities under the constant and random contact patterns. Given the spatial heterogeneity, we show that it can contribute to the increase of basic reproduction number, but also increase the extinction probability of the infectious disease. This study adds novel insights to the course of the impact of heterogeneity on the transmission dynamics and also provides additional evidence for the limited role of reproduction numbers.

On the Interplay of Production Flexibility, Capital Structure, and Investment Timing

Problem definition: Modern technologies have made it viable for firms to lower the costs of switching on and off production in response to market changes. In this paper, we explore how production start–stop flexibility impacts joint operating policies, financing, and investment timing decisions. Methodology/results: We develop a continuous-time, optimal stopping model in which equity holders of the firm make operational decisions regarding pausing and restarting production as well as when to default. The degree of production flexibility is measured by switching costs. On the one hand, production flexibility influences the trade-off between tax shields and default costs for the capital structure decision; on the other hand, debt levels impact the equity holders’ incentive to use flexibility by pausing and restarting operations. We find that optimal debt usage is not monotone in production flexibility. Specifically, when switching costs are in a low region, the optimal debt level decreases slowly as switching costs increase. As switching costs increase into an intermediate region, the optimal debt level decreases sharply because the firm needs to reduce its debt to ensure the equity holders maintain flexible operating policies. However, when switching costs exceed a threshold, the cost of compromising the use of debt becomes excessive, and the firm substantially increases its debt to gain the full benefit of the tax shield; in so doing, the equity holders forgo flexibility and maintain production continuously until default. This financing strategy affects the firm’s investment timing decision, which also exhibits a nonmonotone pattern. Managerial implications: When a firm optimizes the debt usage and investment timing, the incentive of utilizing flexibility embedded in the production technology by the equity holders needs to be taken into account. Our findings also reveal new benefits and guidance for the potential design of incentive contracts to mitigate agency costs. Funding: Q. Wu was supported by Weatherhead School of Management Intramural Grant [Grant IG121420-05-QXW132] for this research. Supplemental Material: The online supplement is available at https://doi.org/10.1287/msom.2022.0213 .

Aerodynamic loads on groups of offshore wind turbine towers stored on quaysides during the pre-assembly phase

Offshore wind turbine towers are pre-assembled and temporarily held in close proximity to each other in group arrangements on port quaysides during which time they are highly sensitive to wind action. Accurate estimates of the aerodynamic loads on the individual towers and on the overall group are therefore essential for the safe and economic design of the quayside’s supporting structures and foundations. Given the many possible group configurations, the key role played by wind direction and the limited literature on this topic, wind tunnel tests represent the main way to address this issue. The problem is that such tests tend to lead to overconservative designs due to inevitable mismatches in the Reynolds number, which is typically subcritical in experiments and transcritical at full scale. This crucial issue is dealt with here using an original engineering solution based on concentrated but discontinuous surface roughness, which allows the satisfactory simulation of the mean loads occurring at high Reynolds number. This case study assumes slender wind turbine towers with a height of 115 m, and for the sake of generality, the investigations focus principally on a cylindrical shape rather than the more complex real-world geometry. The constant diameter of the towers is determined based on the theoretical equivalence of the mean overturning moment. The rationality of this procedure is verified a posteriori using a set of measurements on the real-shape towers. The experiments show a regular behavior of the maximum mean base shear force and moment for towers arranged in double-row groups, while the results are more complicated for the heavily loaded single-row groups; indeed, despite the simulated transcritical regime and the turbulent wind profile, biased flow sometimes occurs in symmetric or nearly-symmetric configurations. Dynamic loads are also inspected, and gust factors in good agreement with Eurocode 1 prescriptions are found. Several parametric studies are carried out, the most extensive of which is devoted to assessing the role of tower height. A complicated non-monotonic pattern of the load coefficients with the tower height is encountered; therefore, the use of simple correction coefficients for practical design purposes must be handled with care. Moreover, the analysis reveals end-effect factors non-negligibly higher than those suggested by Eurocode 1 and ESDU 80025.

Hierarchical Hydration Dynamics of RNA with Nano-Water-Pool at Its Core.

Many functional RNAs fold into a compact, roughly globular shape by minimizing the electrostatic repulsion between their negatively charged phosphodiester backbone. The fold of such close, compact RNA architecture is often so designed that its outer surface and complex core both are predominately populated by phosphate groups loosely sequestering bases in the intermediate layers. A number of helical junctions maintain the RNA core and its nano-water-pool. While the folding of RNA is manifested by its counterion environment composed of mixed mono- and divalent salts, the concerted role of ion and water in maintaining an RNA fold is yet to be explored. In this work, detailed atomistic simulations of SAM-I and Add Adenine riboswitch aptamers, and subgenomic flavivirus RNA (sfRNA) have been performed in a physiological mixed mono- and divalent salt environment. All three RNA systems have compact folds with a core diameter of range 1-1.7 nm. The spatiotemporal heterogeneity of RNA hydration was probed in a layer-wise manner by distinguishing the core, the intermediate, and the outer layers. The layer-wise decomposition of hydrogen bonds and collective single-particle reorientational dynamics reveal a nonmonotonic relaxation pattern with the slowest relaxation observed at the intermediate layers that involves functionally important tertiary motifs. The slowness of this intermediate layer is attributed to two types of long-resident water molecules: (i) water from ion-hydration layers and (ii) structurally trapped water (distant from ions). The relaxation kinetics of the core and the surface water essentially exposed to the phosphate groups show well-separated time scales from the intermediate layers. In the slow intermediate layers, site-specific ions and water control the functional dynamics of important RNA motifs like kink-turn, observed in different structure-probing experiments. Most interestingly, we find that as the size of the RNA core increases (SAM1 core < sfRNAcore < Add adenine core), its hydration tends to show faster relaxation. The hierarchical hydration and the layer-wise base-phosphate composition uniquely portray the globular RNA to act like a soft vesicle with a quasi-dynamic nano-water-pool at its core.

Vigilance end-spurt patterns in event-related potentials

The end-spurt effect, where performance declines with time-on-task and then increases toward the end of a task, has garnered little attention in the vigilance literature. Researchers have suggested the performance enhancement is due to increased motivation or arousal with knowledge of the end of the vigil. However, recent examination of neural signature patterns during a simultaneous discrimination task, where task length was unknown, provided preliminary support that the end-spurt reflects pacing of resources. The current effort expands this previous work to an additional simultaneous task and to a successive discrimination task across two sessions, one where task length was not known and one where task length was known. Twenty-eight (Study 1) and a separate 24 (Study 2) participants completed a Simultaneous Radar task (Study 1) in one session and Simultaneous and Successive Lines tasks (Study 2) across two sessions while neural data was collected. Several event-related potentials exhibited non-monotonic patterns during the vigilance tasks, in some cases reflecting end-spurt patterns, but more commonly reflecting higher-order polynomial patterns. These patterns were more prevalent in anterior regions as opposed to posterior regions. Of note, the N1 anterior exhibited consistent general patterns across all the vigilance tasks and across sessions. Importantly, even when participants had knowledge of session length, some ERPs still exhibited higher-order polynomial trends, suggesting pacing rather than an end-spurt from motivation or arousal as the vigil ends. These insights can help inform predictive modeling of vigilance performance and the implementation of mitigation efforts to allay the vigilance decrement.

Rugged terrain, forest coverage, and insurgency in Myanmar

This paper examines whether non-monotonic patterns exist between forest coverage and conflict processes in Myanmar. Specifically, the paper finds that forest coverage and civil conflict follow an inverted U-shaped relationship: conflict decreases at extremely low and high densities of forest coverage but increases at medium and somewhat high forest densities. Following the logic of the variability of rugged terrain, we argue that this pattern reflects the dual mechanisms of refuge and tactical advantages for rebel groups, who intentionally use such terrain to maximize logistical advantage while minimizing the military advantages enjoyed by better equipped government forces.

DYNAMIC SURFACE PROPERTIES OF FIBRIN

Fibrin is formed via polymerization of one of the main blood proteins, fibrinogen, under the action of an enzyme, thrombin. Dynamic surface elasticity and dynamic surface tension of mixed solutions of fibrinogen and thrombin are measured as functions of surface age and enzyme concentration (50–800 U/L). The nonmonotonic pattern of the dependences for the dynamic surface elasticity indicates the multistage character of fibrin film formation and makes it possible to monitor the transition from unfolded protein to individual filamentous aggregates; a network of branched fibrils; and, finally, a continuous film. The dynamic surface elasticity of fibrin films is twofold higher than the corresponding values for fibrinogen (115 and 55 mN/m, respectively). The use of different types of microscopy makes it possible to assess the morphology of the obtained films.

Absence of consistent pattern between seasons or among species in effect of leaf size on insect herbivory

Insect herbivory on plant leaves is a major determinant of plant fitness, especially the growth and survival of tree seedlings in forests. Leaf size is believed to significantly affect the intensity of herbivory. Studies often assume the relationship between leaf size and herbivory to be monotonic; however, this relationship is influenced by many factors—the magnitude and direction of which are different—indicating a complex non-monotonic pattern. In this study, we investigated the herbivory of 5754 leaves of 422 seedlings belonging to 42 subtropical tree species over two seasons in southwest China. The effects of leaf size on herbivory differed among seasons; a hump-shaped pattern was detected in December, while a pattern of monotonic increase was detected in September. A variety of patterns, including complex non-monotonic hump-shaped patterns, as well as patterns indicating monotonic decrease and increase existed among species, although most species displayed no significant correlations. The relationship between leaf size and insect herbivory did not follow a constant rule, but differed across species and seasons, indicating that the effects of leaf size on the foraging preferences of insect herbivores may be contingent on both external (e.g., temperature) and intrinsic (e.g., other leaf traits) factors. Therefore, a one-off survey focusing on few species may not provide complete understanding of the overall pattern of the effect of leaf size on herbivory. Similar variations may also exist in other ecological processes, which should be given due consideration in future studies on biotic interactions.

Soil Nutrient Distribution and Preferential Flow Transport Patterns in Robinia Pseudoacacia Communities of Degraded Wetlands

The Yellow River Delta wetlands in the Yellow River Delta National Nature Reserve are facing serious degradation due to water scarcity and soil salinization. This study aims to investigate the mechanism of wetland degradation by analyzing the small-scale distribution of soil nutrients and preferential flow transport patterns in the Robinia Pseudoacacia community, which is a typical vegetation community in degraded wetlands. Soil physical and chemical properties based on field staining experiments were analyzed, and indoor solute penetration experiments were conducted to investigate the distribution of soil nutrients and hydrological characteristics. The results showed that the contents of soil organic carbon, organic matter, total nitrogen, and available phosphorus decreased with increasing soil depth, with higher contents in the preferential flow area than in the matrix flow area. Soil organic carbon, organic matter, total nitrogen, total phosphorus, and available phosphorus showed positive correlations with each other, while soil pH and conductivity exhibited negative correlations with the above nutrients. The efflux rate of the Acacia community exhibited a gradual decline as soil depth increased, and the relative concentration of the solution exhibited a non-monotonic pattern of decrease, increase, and subsequent decrease with increasing soil depth. The findings could provide valuable guidance for the restoration and management of degraded wetlands in the Yellow River Delta.

The paradox of adaptive trait clines with nonclinal patterns in the underlying genes

Multivariate climate change presents an urgent need to understand how species adapt to complex environments. Population genetic theory predicts that loci under selection will form monotonic allele frequency clines with their selective environment, which has led to the wide use of genotype-environment associations (GEAs). This study used a set of simulations to elucidate the conditions under which allele frequency clines are more or less likely to evolve as multiple quantitative traits adapt to multivariate environments. Phenotypic clines evolved with nonmonotonic (i.e., nonclinal) patterns in allele frequencies under conditions that promoted unique combinations of mutations to achieve the multivariate optimum in different parts of the landscape. Such conditions resulted from interactions among landscape, demography, pleiotropy, and genetic architecture. GEA methods failed to accurately infer the genetic basis of adaptation under a range of scenarios due to first principles (clinal patterns did not evolve) or statistical issues (clinal patterns evolved but were not detected due to overcorrection for structure). Despite the limitations of GEAs, this study shows that a back-transformation of multivariate ordination can accurately predict individual multivariate traits from genotype and environmental data regardless of whether inference from GEAs was accurate. In addition, frameworks are introduced that can be used by empiricists to quantify the importance of clinal alleles in adaptation. This research highlights that multivariate trait prediction from genotype and environmental data can lead to accurate inference regardless of whether the underlying loci display clinal or nonmonotonic patterns.

Feature and mechanism analysis of dispersive soil disintegration impacted by soil water content, density, and salinity

AbstractDispersive soil has caused innumerable water‐induced erosion failures of earthen structures in arid regions up to now, among which disintegration, as the first response process, is commonly deemed as the primary inducement but with inadequate understanding. In this study, the disintegration characteristics of a compacted dispersive lean clay with sand were investigated by carrying out laboratory disintegration tests under a water immersion regime. Soil mass water content (ω), dry density (ρd) and total soluble salt content (η) were considered. Results suggest that for dispersive soil, (1) the disintegration process exhibited two distinct modes, which was divided by the ω near the optimum water content; (2) higher ρd delayed disintegration monotonously; (3) increasing η first weakened and then enhanced the disintegration, in which pattern the η at the inflection point increased with increasing ρd, showing a density dependence. Evolutions of representative soil morphology were illustrated. More importantly, the underlying influential mechanism of ω and η to disintegration were elaborated emphatically: (1) the initial clay dispersion level, soil consistency change, and conceptual “constraint force” exerted by soil matric suction jointly determine the disintegration modes; (2) increasing η makes the soil pore solution concentration higher and microstructure simpler, competition between the two leads to nonmonotonic change patterns of disintegration completion time (Td) and defined velocity (Vd); the interactive effect of ρd and η manifests that η produces an additional influence on the base of microstructure created by ρd. Finally, the grey relation entropy analysis was introduced to evaluate the contributions of the three test variables to Td and Vd. The obtained results and proposed perspectives are expected to be conducive to a deeper comprehension of the same or relevant behaviours of dispersive soils in the presence of water, so as to provide new insights for the targeted prevention and control of dispersive soil catastrophes.Highlights Disintegration of dispersive soil shows two distinct water content‐dependent modes. Soil salinity has a two phase impact on disintegration of dispersive soil. Dry density and soil salinity interact affecting disintegration. Relationship between soil dispersion and disintegration is elaborated.