Large-scale Behavior Research Articles

The Large-scale Behavior in the Disk of δ Scorpii from 2000 to 2018

Abstract We model the circumstellar disk of δ Sco using the three-dimensional Monte Carlo radiative transfer code HDUST in order to quantify the large-scale changes in the disk through the years 2000–2018, and to see if these changes can be attributed to the secondary star affecting the disk throughout its orbit. We determine our best-fitting models through matching simulated observations to actual Hα spectroscopy and V-band photometric observations. Our modeling results confirm previous findings that the disk of δ Sco was forming early in the century. We also find a period of disk dissipation when the companion is at apastron, as well as a significant growth of the disk between 2009 and 2011, prior to the periastron of 2011. Due to the steady-state nature of the disk after 2011, it is difficult to say whether the variations seen are due to the effect of the close passage of the binary companion.

Improving energy and GHG performance of the rice-wheat rotation system: A life-cycle analysis based on a large-scale behavior investigation

Agricultural production is one of the crucial contributors to energy consumption and greenhouse gas (GHG) emissions. Understanding the various planting behaviors of farmers, instead of taking them as one, can be very helpful for improving crop management efficiency. This information can be used to relieve the pressures of direct and indirect energy use and GHG emissions. In this study, we took Jiangsu Province as an example to estimate the energy and GHG performance of the rice-wheat rotation system from a life-cycle perspective based on a large-scale behavior investigation of 409 samples in 2016. We further studied the influences of regional farmers’ planting characteristics on energy and GHG performance by regression models. The results indicated that farmers’ agricultural inputs varied widely among individuals and regions. Indirect energy consumption and GHG emissions, which are mainly caused by the use of fertilizers and pesticides and vary among farmers, contribute most to the life-cycle energy use and GHG emissions of the crop system in Jiangsu. The life-cycle energy consumption and GHG emissions of rice systems in Jiangsu can be effectively reduced by increasing the planting scales. Statistically, by controlling household characteristics such as the number of farmers involved in agricultural activities, age and education level of the household head, a 1-ha increase in the planting scale would lead to approximately 14.07 J/kcal and 1.676 kg CO2-e/kcal decreases in life-cycle energy consumption and GHG emissions, respectively, in Jiangsu. Policy implications are proposed to reduce and rationally use fertilizer as well as to enlarge the planting scale for sustainable agricultural development in Jiangsu.

Negative representation and instability in democratic elections

The challenge of understanding the collective behaviors of social systems can benefit from methods and concepts from physics [1-6], not because humans are similar to electrons, but because certain large-scale behaviors can be understood without an understanding of the small-scale details [7], in much the same way that sound waves can be understood without an understanding of atoms. Democratic elections are one such behavior. Over the past few decades, physicists have explored scaling patterns in voting and the dynamics of political opinion formation, e.g. [8-13]. Here, we define the concepts of negative representation, in which a shift in electorate opinions produces a shift in the election outcome in the opposite direction, and electoral instability, in which an arbitrarily small change in electorate opinions can dramatically swing the election outcome, and prove that unstable elections necessarily contain negatively represented opinions. Furthermore, in the presence of low voter turnout, increasing polarization of the electorate can drive elections through a transition from a stable to an unstable regime, analogous to the phase transition by which some materials become ferromagnetic below their critical temperatures. Empirical data suggest that United States presidential elections underwent such a phase transition in the 1970s and have since become increasingly unstable.

Complexity Changes in the US and China's Stock Markets: Differences, Causes, and Wider Social Implications.

How different are the emerging and the well-developed stock markets in terms of efficiency? To gain insights into this question, we compared an important emerging market, the Chinese stock market, and the largest and the most developed market, the US stock market. Specifically, we computed the Lempel–Ziv complexity (LZ) and the permutation entropy (PE) from two composite stock indices, the Shanghai stock exchange composite index (SSE) and the Dow Jones industrial average (DJIA), for both low-frequency (daily) and high-frequency (minute-to-minute)stock index data. We found that the US market is basically fully random and consistent with efficient market hypothesis (EMH), irrespective of whether low- or high-frequency stock index data are used. The Chinese market is also largely consistent with the EMH when low-frequency data are used. However, a completely different picture emerges when the high-frequency stock index data are used, irrespective of whether the LZ or PE is computed. In particular, the PE decreases substantially in two significant time windows, each encompassing a rapid market rise and then a few gigantic stock crashes. To gain further insights into the causes of the difference in the complexity changes in the two markets, we computed the Hurst parameter H from the high-frequency stock index data of the two markets and examined their temporal variations. We found that in stark contrast with the US market, whose H is always close to 1/2, which indicates fully random behavior, for the Chinese market, H deviates from 1/2 significantly for time scales up to about 10 min within a day, and varies systemically similar to the PE for time scales from about 10 min to a day. This opens the door for large-scale collective behavior to occur in the Chinese market, including herding behavior and large-scale manipulation as a result of inside information.

Local bounds for stochastic reaction diffusion equations

We prove a priori bounds for solutions of stochastic reaction diffusion equations with super-linear damping in the reaction term. These bounds provide a control on the supremum of solutions on any compact space-time set which only depends on the specific realisation of the noise on a slightly larger set and which holds uniformly over all possible space-time boundary values. This constitutes a space-time version of the so-called “coming down from infinity” property. Bounds of this type are very useful to control the large scale behaviour of solutions effectively and can be used, for example, to construct solutions on the full space even if the driving noise term has no decay at infinity. Our method shows the interplay of the large scale behaviour, dictated by the non-linearity, and the small scale oscillations, dictated by the rough driving noise. As a by-product we show that there is a close relation between the regularity of the driving noise term and the integrability of solutions.

An accurate perturbative approach to redshift space clustering of biased tracers in modified gravity

We extend the scale-dependent Gaussian Streaming Model (GSM) to produce analytical predictions for the anisotropic redshift-space correlation function for biased tracers in modified gravity models. Employing the Convolution Lagrangian Perturbation Theory (CLPT) re-summation scheme, with a local Lagrangian bias schema provided by the peak-background split formalism, we predict the necessary ingredients that enter the GSM, the real-space halo pairwise velocity and the pairwise velocity dispersion. We further consider effective field theory contributions to the pairwise velocity dispersion in order to model correctly its large scale behavior. We apply our method on two widely-considered modified gravity models, the chameleon-screened f(R) Hu-Sawicki model and the nDGP Vainshtein model and compare our predictions against state-of-the-art N-body simulations for these models. We demonstrate that the GSM approach to predict the monopole and the quadrupole of the redshift-space correlation function for halos, gives very good agreement with the simulation data, for a wide range of screening mechanisms, levels of screening and halo masses at z=0.5 and z=1. Our work shows the applicability of the GSM, for cosmologies beyond GR, demonstrating that it can serve as a powerful predictive tool for the next stage of cosmological surveys like DESI, Euclid, LSST and WFIRST.

Live streaming: Data mining and behavior analysis

With the rapid development of mobile communication and Internet technologies, online live streaming has gradually become popular for information communication and entertainment in the new media environment. Live streaming has been widely used in teaching, reality show, E-sports games and events, brand marketing and other aspects. With the active participation of millions of streamers and hundreds of millions of viewers, massive online crowd behavior activity data are generated, which offers rich experimental scenarios for large-scale crowd behavior dynamics research, live streaming channel recommendation and online community evolution. In this paper, we summarize the relevant research literature of live streaming, and review current studies from a comprehensive list of aspects: workload pattern, viewers and streamers behavior, community network discovery and analysis, etc. We summarize the temporal and spatial patterns of live streaming platform workload, heavy tailed effect of large-scale crowd behavior in live streaming platform, etc. We believe that the future work on live streaming can be directed in the examination of formation and evolution mechanism of various community networks formed by large-scale users, as well as the recommendation and detection of live streaming content.

Collective forces in scalar active matter.

Large-scale collective behavior in suspensions of active particles can be understood from the balance of statistical forces emerging beyond the direct microscopic particle interactions. Here we review some aspects of the collective forces that can arise in suspensions of self-propelled active Brownian particles: wall forces under confinement, interfacial forces, and forces on immersed bodies mediated by the suspension. Even for non-aligning active particles, these forces are intimately related to a non-uniform polarization of particle orientations induced by walls and bodies, or inhomogeneous density profiles. We conclude by pointing out future directions and promising areas for the application of collective forces in synthetic active matter, as well as their role in living active matter.

Modelling the multiscale behaviour of claystone: deformation, rupture, and hydro-mechanical phenomena around underground galleries

In the context of underground exploitation, the behaviour of rocks near galleries and tunnels conditions their stability. Underground drilling generates deformations, damage, fracturing, and significant modification of flow characteristics in the surrounding rock. However, the influence of small-scale characteristics and behaviour on the rock deformations and damage at engineering scale remains a complex issue. Consequently, the multiscale behaviour of a clay rock is modelled starting from the large scale of the excavation damaged zone around galleries and then enriching the approach by considering microstructural characteristics from the scale of mineral inclusions. Lastly, a double-scale numerical framework is considered. It allows to relate small- to large-scale rock behaviour in terms of deformations and material rupture. In fact, the development of damage and cracking at microscale allows to predict large-scale fracturing. The developed method focuses on a claystone in the particular context of long-term management of high-level nuclear wastes by deep geological repository. The results highlight the possibilities of double-scale computing in the prediction of the behaviour of underground engineering structures.

Spectral analysis and computation for homogenization of advection diffusion processes in steady flows

Advective diffusion plays a key role in the transport of salt, heat, buoys, and markers in geophysical flows, in the dispersion of pollutants and trace gases in the atmosphere, and even in the dynamics of sea ice floes influenced by winds and ocean currents. The long time, large scale behavior of such systems is equivalent to an enhanced diffusion process with an effective diffusivity matrix D*. Three decades ago, a Stieltjes integral representation for the homogenized matrix, involving a spectral measure of a self-adjoint operator, was developed. However, analytical calculations of D* have been obtained for only a few simple flows, and numerical computations of the effective behavior based on this spectral representation have apparently not been attempted. We overcome these limitations by providing a mathematical foundation for the computation of Stieltjes integral representations of D*. We explore two different approaches and for each approach we derive new Stieltjes integral representations and rigorous bounds for the symmetric and antisymmetric parts of D*, involving the molecular diffusivity and a spectral measure μ of a self-adjoint operator that depends on the characteristics of a randomly perturbed periodic flow. In discrete formulations of each approach, we express μ explicitly in terms of standard (or generalized) eigenvalues and eigenvectors of Hermitian matrices. We develop and implement an efficient numerical algorithm that combines beneficial numerical attributes of each approach. We use this method to compute the effective behavior for model flows and relate spectral characteristics to flow geometry and transport properties.

Lessons from using cluster-randomized evaluations to build evidence on large-scale nutrition behavior change interventions

The recent Nobel Prize in Economics for the use of experimental research to identify solutions to a range of development issues resonates with our work in nutrition. For over a decade, our research team has worked with a global nutrition social and behavior change initiative and used cluster-randomized evaluations, with other methods, to generate lessons about nutrition behaviour change at scale in three countries: Bangladesh, Vietnam, and Ethiopia. We also tested adaptations in other countries. We learned that large-scale behavior change interventions delivered through diverse platforms (government health systems, community-based platforms, and mass media) had substantial impacts but that these impacts differ by context. A body of evidence, based on these evaluations, now informs approaches to shaping nutrition behaviors around the world. Working closely with implementers, sharing research findings and lessons in many forums, and publishing widely, Alive & Thrive has benefited millions of women and children and their communities and influenced millions of dollars of spending on nutrition programs. We conclude that carefully done collaborative program evaluations that use randomized controlled trials together with other methods can support effective learning about solutions, even those that operate at scale.

Modeling discrete fractures in continuum analysis and insights for fracture propagation and mechanical behavior of fractured rock

Abstract This paper presents a procedure for modeling discrete fracture initiation, deformation, and propagation in continuum analysis of rock, and provides numerical simulations to evaluate performance of the procedure against analytical solutions and laboratory data. The procedure is based on aggregating the mechanical behavior of evolving discrete fractures and unfractured rock and provides specific information about fracturing; such as when and where fractures may occur and the type (tensile or shear), geometrical attributes, and aperture of each fracture. By storing fracture geometry as continuum properties that are used internally to generate geometrical parameters needed for analysis, the procedure models the geometry and mechanical behavior of discrete fractures explicitly in continuum analysis without including the fractures in the model grid. Numerical simulations are described for typical laboratory loading conditions such as triaxial compression and extension, and Brazilian testing. The results are compared with laboratory data, analytical solutions, and established concepts to make a case that the procedure performs satisfactorily and can be relied upon for understanding and predicting rock mechanical behavior. Furthermore, the paper discusses insights based on the simulation results for understanding rock fracturing; mechanical behavior of fractured rock; and large-scale behavior such as localization of rock deformation, stress control of fracture mechanisms in failure zones, and conditions for occurrence of multiple parallel fractures.

Wetlandscape size thresholds for ecosystem service delivery: Evidence from the Norrström drainage basin, Sweden

Wetlands are interconnected with the larger surrounding landscape through the hydrological cycling of water and waterborne substances. Therefore, the borders of individual wetlands may not be appropriate landscape system boundaries for understanding large-scale functions and ecosystem services of wetlandscapes (wetland network – landscape systems), and how these can be impacted by climate and land-use changes. Recognizing that such large-scale behaviours may not be easily predicted by simple extrapolation of individual wetland behaviours, we here investigate properties of 15 Swedish wetlandscapes in the extensive (22 650 km2) Norrström drainage basin (NDB) comprising as many as 1699 wetlands. Results based on wetland survey data in combination with GIS-based ecohydrological analyses showed that wetlands located in wetlandscapes above a certain size (in the NDB: ~250 km2) consistently formed networks with characteristics required to support key ecosystem services such as nutrient/pollutant retention and biodiversity support. This was in contrast to smaller wetlandscapes (<250 km2), which had smaller and less diverse wetlands with insufficient throughflow to significantly impact large-scale flows of water and nutrients/pollutants. The existence of such wetlandscape-size thresholds is consistent with scale-dependent flow accumulation patterns in catchments, suggesting likely transferability of this result also to other regions.

Effects of aerosol in simulations of realistic shallow cumulus cloud fields in a large domain

Abstract. Previous study of shallow convection has generally suffered from having to balance domain size with resolution, resulting in high-resolution studies which do not capture large-scale behaviour of the cloud fields. In this work we hope to go some way towards addressing this by carrying out cloud-resolving simulations on large domains. Simulations of trade wind cumulus are carried out using the Met Office Unified Model (UM), based on a case study from the Rain In Cumulus over the Ocean (RICO) field campaign. The UM is run with a nested domain of 500 km with 500 m resolution, in order to capture the large-scale behaviour of the cloud field, and with a double-moment interactive microphysics scheme. Simulations are run using baseline aerosol profiles based on observations from RICO, which are then perturbed. We find that the aerosol perturbations result in changes to the convective behaviour of the cloud field, with higher aerosol leading to an increase (decrease) in the number of deeper (shallower) clouds. However, despite this deepening, there is little increase in the frequency of higher rain rates. This is in contrast to the findings of previous work making use of idealised simulation setups. In further contrast, we find that increasing aerosol results in a persistent increase in domain mean liquid water path and decrease in precipitation, with little impact on cloud fraction.

Information Diffusion and Social Norms Are Associated with Infant and Young Child Feeding Practices in Bangladesh

BackgroundInteraction within mothers’ social networks can theoretically diffuse messages from interventions and campaigns into norms and practices for infant and young child feeding (IYCF).ObjectivesWe hypothesized that mothers’ social networks, diffusion of information, and social norms differed in intensive [intensive interpersonal counseling (IPC), community mobilization (CM), and mass media (MM)] compared with nonintensive (standard IPC and less-intensive CM and MM) intervention areas, were associated with IYCF practices, and partly explained practice improvement.MethodsWe conducted household surveys at endline in 2014 and follow-up in 2016 (n = ∼2000 each round). We used multiple regression to test differences and changes in networks, diffusion, and norms within intervention areas. We analyzed paths from intervention exposure to IYCF practices through networks, diffusion, and norms.ResultsMothers’ networks were larger in intensive than in nonintensive areas in 2014 and increased in both areas over time [25–38 percentage points (pp)]. The prevalence of receipt of IYCF information was high, with no changes over time in intensive areas but an increase in nonintensive areas (8–16 pp). In both areas, more family members and health workers provided IYCF information over time. Sharing of information increased 17–23 pp in intensive and 11–41 pp in nonintensive areas over time. Perceived descriptive norms improved 8–16 pp in intensive and 17–28 pp in nonintensive areas. Perceived injunctive norms were high in both areas. Breastfeeding practices were associated with networks, diffusion, and norms (OR: 1.6–4.4 times larger comparing highest with lowest quartile). Minimum dietary diversity was associated with larger networks and diffusion (OR: 1.5–2.2) but not with social norms. Indirect paths from intervention exposure to practices explained 34–78% of total effects.ConclusionsDiffusion of IYCF information through social networks, reinforced by positive social norms for messages promoted over time, will contribute to positive changes in IYCF practices that may be achieved and sustained through large-scale social and behavior change interventions. This trial was registered at clinicaltrials.gov as NCT0274084.

The fidelity and dose of message delivery on infant and young child feeding practice and nutrition sensitive agriculture in Ethiopia: a qualitative study from the Sustainable Undernutrition Reduction in Ethiopia (SURE) programme

BackgroundIn Ethiopia, 38% of children under 5 years of age are stunted (low height for age). A novel government-led intervention called the Sustainable Undernutrition Reduction in Ethiopia (SURE) aims to tackle the burden of stunting by improving complementary feeding and dietary diversity among young children. The SURE programme design applies a transtheoretical model of behaviour change, whereby exposure to recommended infant and young child feeding (IYCF) and nutrition-sensitive agriculture messages is a first stage to adopting key behaviours. This qualitative study explored the fidelity and dose of the IYCF and nutrition-sensitive agriculture messages delivered by extension workers.MethodsA qualitative study was conducted across four regions in Ethiopia (Oromiya, Amhara, SNNP and Tigray) between April and October 2017. Across the four regions, 81 key informant interviews, 90 FGDs and 81 observations were conducted with 180 extension workers, 18 development agents and 54 mother-father pairs. Digitally recorded audio files were transcribed verbatim, and the data were analysed based on a framework analysis approach using NVivo (version 12) by coding and categorising texts into major themes and sub-themes.ResultsSURE target households had the intended exposure to messages about exclusive breastfeeding, timing of initiation of complementary feeding, food groups, diversified food consumption, irrigation, rearing small animals and vegetables. Few households reported receiving messages on the content or frequency of complementary feeding of a child beyond 6 months of age. Frequency of household visits and hence exposure to SURE messages was also variable. Agricultural messages delivered during household visits focussed on improving standard agricultural practices and rarely covered the importance of nutrition-sensitive agriculture to improve household or child nutrition.ConclusionDespite variability observed in the breadth and depth of messages delivered, large-scale behaviour change communication programmes can achieve moderate to good message exposure among target groups. Qualitative data provide an in-depth insight into fidelity and may supplement our understanding of programme roll-out and implementation. Further research is required to understand longer-term message saturation including frequency and reach.

Repeated long-range migrations of adult males in a common Indo-Pacific reef shark

The grey reef shark, Carcharhinus amblyrhynchos, is one of the most abundant coral reef sharks throughout the Indo-Pacific. However, this species has been critically impacted across its range, with well-documented population declines of > 90% attributed to human activities. A key knowledge gap in the successful implementation of grey reef shark conservation plans is the understanding of large-scale movement patterns, along with the associated biological and ecological drivers. To address this shortfall, we acoustically monitored 147 adult and juvenile grey reef sharks of all sexes for more than 2 yr across the New Caledonian archipelago, West Pacific. Here, we document multiple adult males undertaking return journeys of up to nearly 700 km in consecutive years. This constitutes the first evidence of repeated long-range migrations for this species. Although only a limited number of adult males were definitively tracked undertaking migrations, similar timing in changes in the detection patterns of a further 13 animals, mostly adult males, suggests this behavior may be more common than previously thought. The paucity of evidence for juvenile migrations and timing of adult movements suggest that mating is the motivation behind these migrations. Our results have important implications for management, given the potential of mature individuals to recurrently travel outside managed or protected areas. Future management of this species clearly needs to consider the importance of large-scale migratory behaviors when developing management plans.

Patterns in Aggregated Human Conflict Behaviour

Previous works demonstrated that human creative output fluctuates in periods of 500-years, and more importantly that these periods of creative output maxima occurred simultaneous with increased solar activity. Indeed, early works by Chizhevskiy pointed to the correlation between solar-and-lunar geophysical variables and human behaviour. Interestingly, Persinger, and St. Pierre demonstrated increased aggression in rats during increased geophysical activity. Using these studies as a foundation, we explored the CDB90 Battle Dataset to find a pattern or potential periodicity in large scale human aggressive behaviour – war – specifically within the duration of battles. Using the mean duration of battles for various wars from 1600 to 1950 revealed a 7-day periodicity in military conflicts during the 20th Century, with subharmonics at 14, 22, and 29-days. The existence of the 7-day period in large-scale aggregate behaviour may suggest the reflection of biological cycles also of 7-days, whose original entrainment is likely due to solar and lunar influences. Such entrainment may be why attempts to organize human societies with cycles other than 7-days become superseded by circaseptan systems as they reflect a natural, biological pattern.

An improvement in MATSim computing time for large-scale travel behaviour microsimulation

Coupling activity-based models with dynamic traffic assignment appears to form a promising approach to investigating travel demand. However, such an integrated framework is generally time-consuming, especially for large-scale scenarios. This paper attempts to improve the performance of these kinds of integrated frameworks through some simple adjustments using MATSim as an example. We focus on two specific areas of the model—replanning and time stepping. In the first case we adjust the scoring system for agents to use in assessing their travel plans to include only agents with low plan scores, rather than selecting agents at random, as is the case in the current model. Secondly, we vary the model time step to account for network loading in the execution module of MATSim. The city of Baoding, China is used as a case study. The performance of the proposed methods was assessed through comparison between the improved and original MATSim, calibrated using Cadyts. The results suggest that the first solution can significantly decrease the computing time at the cost of slight increase of model error, but the second solution makes the improved MATSim outperform the original one, both in terms of computing time and model accuracy; Integrating all new proposed methods takes still less computing time and obtains relatively accurate outcomes, compared with those only incorporating one new method.

The role of businesses in facilitating voluntary travel behaviour change - Insights from the London 2012 Olympic Games

The organisers of the London 2012 Olympics faced transport congestion challenges whose resolution required travel behaviour change across an entire transport network. This study evaluates the role of Transport for London's (TfL) £30 m business-focussed Travel Demand Management (TDM) programme in achieving significant traveller behaviour change across its entire transport network. The paper argues that soft TDM measures, together with a targeted ‘hard-edge’ message, alongside travel alternatives, can achieve significant voluntary travel behaviour change (VTBC) across a whole transport network, despite such behaviour normally being habitual.Incorporating a longitudinal study comprised of pre-and post-Games qualitative interviews, office attendance data and analysis of TfL's travel survey with Ajzen's (1991) Theory of Planned Behaviour, this research highlights the importance of reliable information, freedom of choice, and faith in the effectiveness of the measures proposed, in eliciting acceptance of the TDM policy. The results also demonstrate the importance of a relevant, hard-edge message in the form of a ‘big scare’—which operates as a ‘catalyst-for-change’ (CfC), breaking habit by increasing cognitive engagement and acceptance—as well as the importance of the role of businesses in delivering significant levels of voluntary travel behavioural change. The findings contribute to the evaluation of methods for achieving actual VTBC, which could be instrumental in enacting the large-scale travel behaviour changes required to meet international environmental objective of reducing carbon resource consumption by both businesses and individuals.