Oxytocin Effect on Collective Decision Making: A Randomized Placebo Controlled Study

Collective decision making often benefits both the individuals and the group in a variety of contexts. However, for the group to be successful, individuals should be able to strike a balance between their level of competence and their influence on the collective decisions. The hormone oxytocin has been shown to promote trust, conformism and attention to social cues. We wondered if this hormone may increase participants’ (unwarranted) reliance on their partners’ opinion, resulting in a reduction in collective benefit by disturbing the balance between influence and competence. To test this hypothesis we employed a randomized double-blind placebo-controlled design in which male dyads self-administered intranasal oxytocin or placebo and then performed a visual search task together. Compared to placebo, collective benefit did not decrease under oxytocin. Using an exploratory time dependent analysis, we observed increase in collective benefit over time under oxytocin. Moreover, trial-by-trial analysis showed that under oxytocin the more competent member of each dyad was less likely to change his mind during disagreements, while the less competent member showed a greater willingness to change his mind and conform to the opinion of his more reliable partner. This role-dependent effect may be mediated by enhanced monitoring of own and other’s performance level under oxytocin. Such enhanced social learning could improve the balance between influence and competence and lead to efficient and beneficial collaboration.     

From Aggregation to Dispersion: How Habitat Fragmentation Prevents the Emergence of Consensual Decision Making in a Group

In fragmented landscape, individuals have to cope with the fragmentation level in order to aggregate in the same patch and take advantage of group-living. Aggregation results from responses to environmental heterogeneities and/or positive influence of the presence of congeners. In this context, the fragmentation of resting sites highlights how individuals make a compromise between two individual preferences: (1) being aggregated with conspecifics and (2) having access to these resting sites. As in previous studies, when the carrying capacity of available resting sites is large enough to contain the entire group, a single aggregation site is collectively selected. In this study, we have uncoupled fragmentation and habitat loss: the population size and total surface of the resting sites are maintained at a constant value, an increase in fragmentation implies a decrease in the carrying capacity of each shelter. For our model organism, Blattella germanica, our experimental and theoretical approach shows that, for low fragmentation level, a single resting site is collectively selected. However, for higher level of fragmentation, individuals are randomly distributed between fragments and the total sheltered population decreases. In the latter case, social amplification process is not activated and consequently, consensual decision making cannot emerge and the distribution of individuals among sites is only driven by their individual propensity to find a site. This intimate relation between aggregation pattern and landscape patchiness described in our theoretical model is generic for several gregarious species. We expect that any group-living species showing the same structure of interactions should present the same type of dispersion-aggregation response to fragmentation regardless of their level of social complexity.     

A New Type of Rhythmic Plant Movement: Mocronutation

A low amplitude oscillatory movement, distinct from the nutationalmovements occuring in the same plant, has been found to occurin seedling plants of runner bean. The frequency of the oscillationis between two and five cycles per hour, and appears to havea temperature coefficient of 2.24 in the range 15–25°C.The theoretical implication of this oscillation on the ‘geotropichunting’ theory of nutation is discussed.     

Earthworms in Soil Restoration: Lessons Learned from United Kingdom Case Studies of Land Reclamation

Restoration ecology requires theoretical consideration of a habitat’s former structure and function before the practice of ecological restoration is applied. However, experience has shown that this does not always occur and aspects such as soil ecology have often been an afterthought. Here, case study material relates the use of earthworms at selected sites in the United Kingdom. Due to their soil‐forming capabilities, these organisms may be essential to reconstruction of soils when drastic activities have despoiled an area. While describing in brief the type of work undertaken, these case studies seek to illustrate some of the misunderstandings/problems/deliberately negative acts that have too often accompanied use of earthworms in soil restoration. From such experiences, implications for practice are suggested that should lead to a greater understanding and appropriate utilization of earthworms in future projects.     

Stochastic Collective Movement of Cells and Fingering Morphology: No Maverick Cells

The classical approach to model collective biological cell movement is through coupled nonlinear reaction-diffusion equations for biological cells and diffusive chemicals that interact with the biological cells. This approach takes into account the diffusion of cells, proliferation, death of cells, and chemotaxis. Whereas the classical approach has many advantages, it fails to consider many factors that affect multicell movement. In this work, a multiscale approach, the Glazier-Graner-Hogeweg model, is used. This model is implemented for biological cells coupled with the finite element method for a diffusive chemical. The Glazier-Graner-Hogeweg model takes the biological cell state as discrete and allows it to include cohesive forces between biological cells, deformation of cells, following the path of a single cell, and stochastic behavior of the cells. Where the continuity of the tissue at the epidermis is violated, biological cells regenerate skin to heal the wound. We assume that the cells secrete a diffusive chemical when they feel a wounded region and that the cells are attracted by the chemical they release (chemotaxis). Under certain parameters, the front encounters a fingering morphology, and two fronts progressing against each other are attracted and correlated. Cell flow exhibits interesting patterns, and a drift effect on the chemical may influence the cells' motion. The effects of a polarized substrate are also discussed.     

Ecotoxicological Effects of Nanomaterials on Earthworms: A Review

The concern regarding the ecotoxicological effects of nanomaterials in the terrestrial environment is increasing. Against this background, several studies have investigated the effects of different nanomaterials on various earthworm species. Since the earthworm is a representative invertebrate present in soil and occupies an important trophic level, many studies have focused on earthworms. Understanding how and why nanoparticles are toxic to organisms is important to nanotoxicologists and ecotoxicologists. We have collated information from studies on the toxicity of metal- and carbon-based nanomaterials to earthworms in the soil matrix, and trends in the adverse effects of nanomaterials on earthworms were analyzed. Most studies showed that the survival and growth of adult earthworms are negligibly affected by nanomaterials in the soil. However, many studies reported that nanomaterials may result in a reduction in the reproductive activity. This study presents an intensive overall view of the ecotoxicological impact of nanomaterials on earthworms at the organism, cellular, and molecular levels.     

Collective Cell Movement Promotes Synchronization of Coupled Genetic Oscillators

Collective cell movement is a crucial component of embryonic development. Intercellular interactions regulate collective cell movement by allowing cells to transfer information. A key question is how collective cell movement itself influences information flow produced in tissues by intercellular interactions. Here, we study the effect of collective cell movement on the synchronization of locally coupled genetic oscillators. This study is motivated by the segmentation clock in zebrafish somitogenesis, where short-range correlated movement of cells has been observed. We describe the segmentation clock tissue by a Voronoi diagram, cell movement by the force balance of self-propelled and repulsive forces between cells, the dynamics of the direction of self-propelled motion, and the synchronization of genetic oscillators by locally coupled phase oscillators. We find that movement with a correlation length of about 2 ∼ 3 cell diameters is optimal for the synchronization of coupled oscillators. Quantification of cell mixing reveals that this short-range correlation of cell movement allows cells to exchange neighbors most efficiently. Moreover, short-range correlated movement strongly destabilizes nonuniform spatial phase patterns, further promoting global synchronization. Our theoretical results suggest that collective cell movement may enhance the synchronization of the segmentation clock in zebrafish somitogenesis. More generally, collective cell movement may promote information flow in tissues by enhancing cell mixing and destabilizing spurious patterns.     

Applications of Decision Support System: A Case Study of Solanaceous Vegetables

Crop simulation models constitute the major proportion in decision support systems. A large number of crop models have been developed for potato and few for tomato and peppers. In the literature, thirty three crop models have been reported to simulate potato, nine for tomato and six for peppers. Some of these models dealt with the climate change scenario and others with the crop management practices such as sowing time, irrigation, nitrogen, and insect-pests management. The most evaluated and applied models for potato include; SUBSTOR, and LINTUL-Potato, whereas CROPGRO-tomato model is the most tested and applied for tomato. The AQUACROP is the most widely used model to simulate the water dynamics. The CROPGRO model has been tested for elevated temperatures and CO₂ under greenhouse conditions for tomato. In tomato and peppers, almost similar models have been applied for field conditions as well as under greenhouse environments with some modifications. Nitrogen dynamics has been widely tested by employing the EU-Rotate-N model for tomato and peppers. Simulation studies dealing with changing climate conditions are rare in potato and are not found for tomato and peppers. To modify potato, tomato and peppers models for climate impact studies, it is required that they are (a) calibrated and evaluated with new cultivars under various agro-environmental conditions and (b) assessed under varying field conditions under changing climates and crop management practices, including temperature increases, water and nutrient management and their interactions. These comprehensive model studies and modifications need a collaborative international effort and a multi-year, large scale field research studies on potato, tomato and peppers.     

Collective Cell Movement Promotes Synchronization of Coupled Genetic Oscillators

Collective cell movement is a crucial component of embryonic development. Intercellular interactions regulate collective cell movement by allowing cells to transfer information. A key question is how collective cell movement itself influences information flow produced in tissues by intercellular interactions. Here, we study the effect of collective cell movement on the synchronization of locally coupled genetic oscillators. This study is motivated by the segmentation clock in zebrafish somitogenesis, where short-range correlated movement of cells has been observed. We describe the segmentation clock tissue by a Voronoi diagram, cell movement by the force balance of self-propelled and repulsive forces between cells, the dynamics of the direction of self-propelled motion, and the synchronization of genetic oscillators by locally coupled phase oscillators. We find that movement with a correlation length of about 2 ∼ 3 cell diameters is optimal for the synchronization of coupled oscillators. Quantification of cell mixing reveals that this short-range correlation of cell movement allows cells to exchange neighbors most efficiently. Moreover, short-range correlated movement strongly destabilizes nonuniform spatial phase patterns, further promoting global synchronization. Our theoretical results suggest that collective cell movement may enhance the synchronization of the segmentation clock in zebrafish somitogenesis. More generally, collective cell movement may promote information flow in tissues by enhancing cell mixing and destabilizing spurious patterns.     

Dynamics of Collective Decision Making of Honeybees in Complex Temperature Fields

Endothermic heat production is a crucial evolutionary adaptation that is, amongst others, responsible for the great success of honeybees. Endothermy ensures the survival of the colonies in harsh environments and is involved in the maintenance of the brood nest temperature, which is fundamental for the breeding and further development of healthy individuals and thus the foraging and reproduction success of this species. Freshly emerged honeybees are not yet able to produce heat endothermically and thus developed behavioural patterns that result in the location of these young bees within the warm brood nest where they further develop and perform tasks for the colony. Previous studies showed that groups of young ectothermic honeybees exposed to a temperature gradient collectively aggregate at the optimal place with their preferred temperature of 36°C but most single bees do not locate themselves at the optimum. In this work we further investigate the behavioural patterns that lead to this collective thermotaxis. We tested single and groups of young bees concerning their ability to discriminate a local from a global temperature optimum and, for groups of bees, analysed the speed of the decision making process as well as density dependent effects by varying group sizes. We found that the majority of tested single bees do not locate themselves at the optimum whereas sufficiently large groups of bees are able to collectively discriminate a suboptimal temperature spot and aggregate at 36°C. Larger groups decide faster than smaller ones, but in larger groups a higher percentage of bees may switch to the sub-optimum due to crowding effects. We show that the collective thermotaxis is a simple but well evolved, scalable and robust social behaviour that enables the collective of bees to perform complex tasks despite the limited abilities of each individual.     

正畸牙移动中的潜在新角色:牙周膜肌成纤维细胞

肌成纤维细胞(myofibroblasts,MFb)是一种具有出色的应力敏感性和基质合成功能的细胞,在纤维性疾病和瘢痕挛缩中发挥重要作用。在口腔医学领域,MFb同样存在于牙周膜中,且在牙移动过程中显著增多并可能发挥一定作用。现对MFb的特征、功能及分化来源进行介绍,并在此基础上综述肌成纤维细胞发挥功能的生物学基础和应力刺激下可能影响其分化形成的相关信号通路及串话,分析MFb在传递正畸力、促进牙周组织改建中的潜在作用及牙移动过程中可能影响牙周膜肌成纤维细胞分化形成的机制,以期为探索牙周膜肌成纤维细胞的功能、研究正畸牙移动提供新思路。     

Factors Affecting Distribution of Earthworms in Kashmir Valley: A Multivariate Statistical Approach

Soil characteristics influence earthworm population dynamics, species distribution and community structure. According in the present study an attempt was made to determine the soil physiochemical factors influencing earthworms of Kashmir valley with a view to improve the soil productivity by enhancing earthworm diversity under different pedoecosystems. Data collection on 15 soil parameters from 20 earthworm inhabiting sites revealed significant variation within and among the sites in soil temperature (F_{23, 19} = 148.83, 9.71; P < 0.05), moisture (F_{23, 19} = 16.91, 46.20; P < 0.05), pH (F₁₉ = 47.21; P < 0.05), electrical conductivity (F_{23, 19} = 11.67, 87.13; P < 0.05), sodium (F_{23, 19} = 2.46, 211.25; P < 0.05), potassium (F₁₉ = 22.91; P < 0.05), calcium (F₁₉ = 15.90; P < 0.05), magnesium (F_{23, 19} = 1.76, 104.51; P < 0.05), organic carbon (F_{23, 19} = 64.60, 222.50; P < 0.05), organic nitrogen (F_{23, 19} = 4.59, 3.81; P < 0.05) and phosphorous (F_{23, 19} = 5.11, 137.87; P < 0.05). Aporrectodea caliginosa trapezoides and A. rosea rosea exhibited wide range of distribution whereas Octolasion cyaneum, A. c. trapezoides and A. parva showed restricted distribution. Hierarchical cluster analysis grouped 20 earthworm collection sites into three clusters—earthworm absent sites, low earthworm diversity sites and moderate earthworm diversity sites. Principal component analysis assisted from the data set of 20 sites, resulting into four latent factors accounting for 77.95 % of total variance, identified the factors affecting earthworm communities are mainly related to physical habitat factor, chemical factor, soil texture factor and growth factor, each accounting for 26.41, 20.16, 18.25 and 13.13 % of total variance respectively.     

Interaction between Earthworms and Arbuscular Mycorrhizal Fungi in Plants: A Review

Different kinds of soil animals and microorganisms inhabit the plant rhizosphere, which function closely to plant roots. Of them, arbuscular mycorrhizal fungi (AMF) and earthworms play a critical role in sustaining the soil-plant health. Earthworms and AMF belong to the soil community and are soil beneficial organisms at different trophic levels. Both of them improve soil fertility and structural development, collectively promoting plant growth and nutrient acquisition capacity. Earthworm activities redistribute mycorrhizal fungi spores and give diversified effects on root mycorrhizal fungal colonization. Dual inoculation with both earthworms and AMF strongly magnifies the response on plant growth through increased soil enzyme activities and changes in soil nutrient availability, collectively mitigating the negative effects of heavy metal pollution in plants and soils. This thus enhances phytoremediation and plant disease resistance. This review simply outlines the effects of earthworms and AMF on the soil-plant relationship. The effects of earthworms on root AMF colonization and activities are also analyzed. This paper also summarizes the interaction between earthworms and AMF on plants along with suggested future research.     

Scale‐dependent Orientation in Movement Paths: A Case Study of an African Viper

Decisions relating to the orientation of movement by animals and how this translates into movement patterns can occur at multiple spatial scales simultaneously, but this interaction is poorly understood for many groups of animals. Using the tracks left by moving snakes in their sandy habitat, we studied the movement paths of the African snake Bitis schneideri (Namaqua dwarf adder) for evidence of broad‐scale directional persistence and short‐range avoidance of exposure. Although snakes clearly displayed directional persistence, they preferentially moved to nearby shrubs, thereby minimizing exposure to solar and thermal radiation and/or predation. Thus, snakes made decisions relating to orientation at a minimum of two scales, the interaction of which resulted in snakes moving ≈17% (mean straightness index = 0.85) further than the simple broad‐scale straight‐line distance. We assert that the actual path chosen by moving snakes represents a trade‐off of various costs and risks that include risk of predation, exposure to the elements, time and energy expenditure. Our study highlights the need for cognizance of the possibility of the scale dependence of orientation and movement in studies of snake movement, and adds to a growing literature demonstrating previously unrecognized behavioural complexity in snakes.     

Geriatric Fever Score: A New Decision Rule for Geriatric Care

Background

Evaluating geriatric patients with fever is time-consuming and challenging. We investigated independent mortality predictors of geriatric patients with fever and developed a prediction rule for emergency care, critical care, and geriatric care physicians to classify patients into mortality risk and disposition groups.

Materials and Methods

Consecutive geriatric patients (≥65 years old) visiting the emergency department (ED) of a university-affiliated medical center between June 1 and July 21, 2010, were enrolled when they met the criteria of fever: a tympanic temperature ≥37.2°C or a baseline temperature elevated ≥1.3°C. Thirty-day mortality was the primary endpoint. Internal validation with bootstrap re-sampling was done.

Results

Three hundred thirty geriatric patients were enrolled. We found three independent mortality predictors: Leukocytosis (WBC >12,000 cells/mm³), Severe coma (GCS ≤ 8), and Thrombocytopenia (platelets <150 10³/mm³) (LST). After assigning weights to each predictor, we developed a Geriatric Fever Score that stratifies patients into two mortality-risk and disposition groups: low (4.0%) (95% CI: 2.3–6.9%): a general ward or treatment in the ED then discharge and high (30.3%) (95% CI: 17.4–47.3%): consider the intensive care unit. The area under the curve for the rule was 0.73.

Conclusions

We found that the Geriatric Fever Score is a simple and rapid rule for predicting 30-day mortality and classifying mortality risk and disposition in geriatric patients with fever, although external validation should be performed to confirm its usefulness in other clinical settings. It might help preserve medical resources for patients in greater need.     

Computer Simulation of Leadership,Consensus Decision Making and Collective Behaviour in Humans

The aim of this study is to evaluate the reliability of a crowd simulation model developed by the authors by reproducing Dyer et al.''s experiments (published in Philosophical Transactions in 2009) on human leadership and consensus decision making in a computer-based environment. The theoretical crowd model of the simulation environment is presented, and its results are compared and analysed against Dyer et al.''s original experiments. It is concluded that the simulation results are largely consistent with the experiments, which demonstrates the reliability of the crowd model. Furthermore, the simulation data also reveals several additional new findings, namely: 1) the phenomena of sacrificing accuracy to reach a quicker consensus decision found in ants colonies was also discovered in the simulation; 2) the ability of reaching consensus in groups has a direct impact on the time and accuracy of arriving at the target position; 3) the positions of the informed individuals or leaders in the crowd could have significant impact on the overall crowd movement; and 4) the simulation also confirmed Dyer et al.''s anecdotal evidence of the proportion of the leadership in large crowds and its effect on crowd movement. The potential applications of these findings are highlighted in the final discussion of this paper.