Factors inducing morphological transition in harmful algal bloom-forming species Phaeocystis globosa with emphasis on predator chemical cue

The microalga Phaeocystis globosa is recognized as a harmful alga and also one of the few keystone phytoplankton genera that shape the structure and function of marine ecosystems.P.globosa possess a complex polymorphic life cycle,exhibiting phase alternation between free-living cells of approximately 3-6μm in diameter and gelatinous colonies(palmelloid stage)reaching several millimeters.The knowledge on the factors that induced the morphological transition of P.globosa in the last two decades was reviewed.Emphasis is given to infochemicals,an additional biological factor induced by predator,with the attempt to reveal a relevant mechanism of induced morphological defense.

A cooperative detection game:UAV swarm vs.one fast intruder

This paper studies a special defense game using unmanned aerial vehicle(UAV)swarm against a fast intruder.The fast intruder applies an offensive strategy based on the artificial potential field method and Apollonius circle to scout a certain destination.As defenders,the UAVs are arranged into three layers:the forward layer,the midfield layer and the back layer.The co-defense mechanism,including the role derivation method of UAV swarm and a guidance law based on the co-defense front point,is introduced for UAV swarm to co-detect the intruder.Besides,five formations are designed for comparative analysis when ten UAVs are applied.Through Monte Carlo experiments and ablation experiment,the effectiveness of the proposed co-defense method has been verified.

Attack and Defense Strategies in Complex Networks Based on Game Theory

To investigate the attack and defense strategies in complex net works,the authors propose a two-player zero-sum static game model with complete information which considers attack and defense strategies simultaneously.The authors assume that both the attacker and defender have two typical strategies:Targeted strategy and random strategy.The authors explore the Nash equilibriums of the attacker-defender game and demonstrate that when the attacker's attack resources are not so significantly abundant as the defender's resources,there exists a pure-strategy Nash equilibrium in both model net works and real-world net works,in which the defender protects the hub t arge ts with large degrees preferentially,while the attacker prefers selecting the targets randomly.When the attack resources are much higher than defense resources,both the attacker and the defender adopt the targeted strategy in equilibriums.This paper provides a new theoretical framework for the study of attack and defense st rat egies in complex net works.

Cascading failure analysis of power flow on wind power based on complex network theory

Cascading failure is a potential threat in power systems with the scale development of wind power,especially for the large-scale grid-connected and long distance transmission wind power base in China.This introduces a complex network theory(CNT)for cascading failure analysis considering wind farm integration.A cascading failure power flow analysis model for complex power networks is established with improved network topology principles and methods.The network load and boundary conditions are determined to reflect the operational states of power systems.Three typical network evaluation indicators are used to evaluate the topology characteristics of power network before and after malfunction including connectivity level,global effective performance and percentage of load loss(PLL).The impacts of node removal,grid current tolerance capability,wind power instantaneous penetrations,and wind farm coupling points on the power grid are analyzed based on the IEEE 30 bus system.Through the simulation analysis,the occurrence mechanism and main influence factors of cascading failure are determined.Finally,corresponding defense strategies are proposed to reduce the hazards of cascading failure in power systems.

To eat or not to eat-relationship of lichen herbivory by snails with secondary compounds and field frequency of lichens

Aims The biochemical defense of lichens against herbivores and its rela-tionship to lichen frequency are poorly understood.Therefore,we tested whether chemical compounds in lichens act as feeding defense or rather as stimulus for snail herbivory among lichens and whether experimental feeding by snails is related to lichen fre-quency in the field.Methods In a no-choice feeding experiment,we fed 24 lichen species to snails of two taxa from the Clausilidae and Enidae families and compared untreated lichens and lichens with compounds removed by acetone rinsing.Then,we related experimental lichen consump-tion with the frequency of lichen species among 158 forest plots in the field(schwäbische alb,germany),where we had also sampled snail and lichen species.Important findings In five lichen species,snails preferred treated samples over untreated controls,indicating chemical feeding defense,and vice versa in two species,indicating chemical feeding stimulus.Interestingly,com-pared with less frequent lichen species,snails consumed more of untreated and less of treated samples of more frequent lichen spe-cies.removing one outlier species resulted in the loss of a significant positive relationship when untreated samples were analyzed separately.However,the interaction between treatment and lichen frequency remained significant when excluding single species or including snail genus instead of taxa,indicating that our results were robust and that lumping the species to two taxa was justified.our results imply lichen-feeding snails to prefer frequent lichens and avoid less frequent ones because of secondary compound rec-ognition.This supports the idea that consumers adapt to the most abundant food source.