Classical Cascade Research Articles

Adaptive Linear Predictive Model of an Improved Predictive Control of Permanent Magnet Synchronous Motor Over Different Speed Regions

Model predictive control (MPC) strategy can provide significant benefits for controlling nonlinear systems over classical cascade field-oriented control (FOC). However, the MPC is still in the development stage for a high-performance predictive model. Therefore, the proposed MPC in this article updates the internal linear predictive model at each time step to accurately represent the nonlinear plant of a permanent-magnet synchronous motor (PMSM) plant over different speed regions. In other words, the adaptive discrete linear plant model (ADLPM) is designed to update the current operating conditions of the machine parameters and the equilibrium points of the measured stator currents, speed, and load torque. For the operation in the flux-weakening region, the proposed MPC depends on a performance control algorithm (PCA) to obtain high dynamic performance. In this PCA algorithm, the proposed MPC depends on the modified reference velocity rather than the original reference velocity, which can calculate the required <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis cur <underline xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</u> ent directly. Moreover, the proposed cost function is designed directly in terms of the error values of the velocity and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis current, which fits the motor performance based on the further constraint of the maximum magnitude of the drawn stator current provided to control the acceleration of the rotor. Finally, comprehensive simulations and experiments have fully demonstrated that the proposed MPC can reduce the speed drop, and torque ripple in response to those of the FOC and traditional MPC strategies.

Cascade conditions in electron magneto-hydrodynamic turbulence

The basic features of electron whistler waves can be described by electron magneto-hydrodynamics. In terms of this model, we discuss criteria and relevant parameter ranges for dual and forward cascades in electron whistler turbulence. It is an advantage to use the set of eigenfunctions for the “curl” operator in the analysis. It is demonstrated that three wavemodes with same helicity support a dual cascade as know also from spatially two dimensional turbulence, while modes with mixed helicities include the classical cascade of energy from long to shorter wavelengths. The analysis is based on the conservation of energy and magnetic helicity during the wave interactions. For stationary conditions in large closed systems, a detailed balance can be expected. It is, however, possible for large-scale self-organized structures to develop as transient phenomena. These can be found when solving initial value problem with a strong imbalance of positive and negative helicities. For plasmas in nature or laboratory, similar conditions can occur when the system has boundary conditions with preference for emission of oscillations with one sign of helicity.

Crowding in the middle of marine food webs: A focus on Raja asterias and other mediterranean batoids

The Mediterranean Sea is among the three biodiversity hotspots of the world where elasmobranchs are severely threatened. Elasmobranchs act as apex or meso-predators within marine food webs and the loss/decline of apex predators determines the mesopredator release, leading in turn to increased predation on smaller prey. However, also several mesopredators (including rays, skates and small sharks) are intensively fished, being of commercial interest, or by-caught, and thus mesopredators increase could not be so evident. We analysed the trophic ecology of an endemic Mediterranean ray, the starry ray Raja asterias, at a seasonal scale from the Adriatic basin, one of the most intensively exploited area of the Mediterranean, by means of stomach contents and stable isotopes analyses. Our results evidenced that starry rays rely on benthic sources including species of local commercial values, such as swimming crabs, small cephalopods, and stomatopods and share the same trophic position with other elasmobranchs (rays, skates, and small sharks) and other mesopredators (e.g., common soles, Norway lobsters and mullets). As all mesopredators are overexploited, as well as their benthic prey are affected by intense trawl-fishing, the whole food webs are disrupted and neither the classical trophic cascade nor the mesopredator release hypothesis could be verified. Conservation measures for these species, such as the release after capture or the application of exclusion grids to the net, should be applied in areas where populations are strongly impacted by trawling.

Non-equilibrium dissipation scaling in atmospheric turbulence

This work is devoted to the detection of non-equilibrium turbulence states in atmospheric turbulence. The non-equilibrium scaling contradicts the classical Richardson-Kolmogorov cascade picture and many turbulence models do not account for it. The existence of such scaling has been discovered in various laboratory experiments. We show here that non-equilibrium states are also present in the stratocumulus-topped boundary layers, which indicates the presence rapidly changing external conditions.

The effect of particle anisotropy on the modulation of turbulent flows

We investigate the modulation of turbulence caused by the presence of finite-size dispersed particles. Bluff (isotropic) spheres versus slender (anisotropic) fibres are considered to understand the influence of the shape of the objects on altering the carrier flow. While at a fixed mass fraction – but different Stokes number – both objects provide a similar bulk effect characterized by a large-scale energy depletion, a scale-by-scale analysis of the energy transfer reveals that the alteration of the whole spectrum is intrinsically different. For bluff objects, the classical energy cascade shrinks in its extension but is unaltered in the energy content and its typical features, while for slender ones we find an alternative energy flux which is essentially mediated by the fluid–solid coupling.

Electrochemical cascade reactions for electro-organic synthesis

Electrochemical cascades are an attractive tool for use in organic synthesis, providing an elegant pathway for one-pot synthesis of important chemical feedstocks. These cascade reactions typically consist of an electrochemical redox event that enables several (two or more) subsequent spontaneous chemical reactions. While classic organic cascades typically require stoichiometric amounts of reagents, especially reactive redox reagents, electrochemical methods replace stoichiometric reagents with an applied potential, offering a more sustainable synthetic route with high atom economy. This review highlights advances in the rapidly growing field by highlighting the use of metal-mediated, metal-free, and bioelectrocatlytic cascade reactions in electro-organic synthesis. As electrochemical cascade systems embrace the complexity and advances of modern electrochemical catalysis, there is likely to be greater increases in selectivity and efficiency.

A User Centric Blockage Model for Wireless Networks

This paper proposes a cascade blockage model for analyzing the vision that a user has of a wireless network. This model, inspired by the classical multiplicative cascade models, has a radial structure meant to analyze blockages seen by the receiver at the origin in different angular sectors. The main novelty is that it is based on the geometry of obstacles and takes the joint blockage phenomenon into account. We show on a couple of simple instances that the Laplace transforms of total interference satisfies a functional equation that can be solved efficiently by an iterative scheme. This is used to analyze the coverage probability of the receiver and the effect of blockage correlation and penetration loss in both dense and sparse blockage environments. Furthermore, this model is used to investigate the effect of blockage correlation on user beamforming techniques. Another functional equation and its associated iterative algorithm are proposed to derive the coverage performance of the best beam selection in this context. In addition, the conditional coverage probability is also derived to evaluate the effect of beam switching. The results not only show that beam selection is quite efficient for multi-beam terminals, but also show how the correlation brought by blockages can be leveraged to accelerate beam sweeping and pairing.

Unifying information propagation models on networks and influence maximization.

Information propagation on networks is a central theme in social, behavioral, and economic sciences, with important theoretical and practical implications, such as the influence maximization problem for viral marketing. Here we consider a model that unifies the classical independent cascade models and the linear threshold models, and generalize them by considering continuous variables and allowing feedback in the dynamics. We then formulate its influence maximization as a mixed integer nonlinear programming problem and adopt derivative-free methods. Furthermore, we show that the problem can be exactly solved in the special case of linear dynamics, where the selection criterion is closely related to the Katz centrality, and propose a customized direct search method with local convergence. We then demonstrate the close to optimal performance of the customized direct search numerically on both synthetic and real networks.

An Influence Maximization Algorithm for Dynamic Social Networks Based on Effective Links

The connection between users in social networks can be maintained for a certain period of time, and the static network structure formed provides the basic conditions for various kinds of research, especially for discovering customer groups that can generate great influence, which is important for product promotion, epidemic prevention and control, and public opinion supervision, etc. However, the computational process of influence maximization ignores the timeliness of interaction behaviors among users, the screened target users cannot diffuse information well, and the time complexity of relying on greedy rules to handle the influence maximization problem is high. Therefore, this paper analyzes the influence of the interaction between nodes in dynamic social networks on information dissemination, extends the classical independent cascade model to a dynamic social network dissemination model based on effective links, and proposes a two-stage influence maximization solution algorithm (Outdegree Effective Link—OEL) based on node degree and effective links to enhance the efficiency of problem solving. In order to verify the effectiveness of the algorithm, five typical influence maximization methods are compared and analyzed on four real data sets. The results show that the OEL algorithm has good performance in propagation range and running time.

Herpes Simplex Virus 1 Expressing GFP-Tagged Virion Host Shutoff (vhs) Protein Uncouples the Activities of RNA Degradation and Differential Nuclear Retention of the Virus Transcriptome.

ABSTRACTVirion host shutoff (vhs) protein is an endoribonuclease encoded by herpes simplex virus 1 (HSV1). vhs causes several changes to the infected cell environment that favor the translation of late (L) virus proteins: cellular mRNAs are degraded, immediate early (IE) and early (E) viral transcripts are sequestered in the nucleus with polyA binding protein (PABPC1), and dsRNA is degraded to help dampen the PKR-dependent stress response. To further our understanding of the cell biology of vhs, we constructed a virus expressing vhs tagged at its C terminus with GFP. When first expressed, vhs-GFP localized to juxtanuclear clusters, and later it colocalized and interacted with its binding partner VP16, and was packaged into virions. Despite vhs-GFP maintaining activity when expressed in isolation, it failed to degrade mRNA or relocalise PABPC1 during infection, while viral transcript levels were similar to those seen for a vhs knockout virus. PKR phosphorylation was also enhanced in vhs-GFP infected cells, which is in line with a failure to degrade dsRNA. Nonetheless, mRNA FISH revealed that as in Wt but not Dvhs infection, IE and E, but not L transcripts were retained in the nucleus of vhs-GFP infected cells at late times. These results revealed that the vhs-induced nuclear retention of IE and E transcripts was dependent on vhs expression but not on its endoribonuclease activity, uncoupling these two functions of vhs.IMPORTANCE Like many viruses, herpes simplex virus 1 (HSV1) expresses an endoribonuclease, the virion host shutoff (vhs) protein, which regulates the RNA environment of the infected cell and facilitates the classical cascade of virus protein translation. It does this by causing the degradation of some mRNA molecules and the nuclear retention of others. Here, we describe a virus expressing vhs tagged at its C terminus with a green fluorescent protein (GFP) and show that the vhs-GFP fusion protein retains the physical properties of native vhs but does not induce the degradation of mRNA. Nonetheless, vhs-GFP maintains the ability to trap the early virus transcriptome in the nucleus to favor late protein translation, proving for the first time that mRNA degradation is not a prerequisite for vhs effects on the nuclear transcriptome. This virus, therefore, has uncoupled the nuclear retention and degradation activities of vhs, providing a new understanding of vhs during infection.

Catalytic activity in vitro of the human protein kinase ASK1 mutants: Experimental and molecular simulation study

Kinases have become an important class of targets for drug discovery since the milestone approval of imatinib in 2001. Although a great success has been achieved for targeting kinases with over 70 inhibitors approved by the FDA, it is inevitable that drug resistance would emerge during treatment. Thus, assessment of the kinase mutations is an essential issue for the development of the next generation inhibitors. Apoptosis signal-regulating kinase 1 (ASK1) is a crucial regulator of classical mitogen-activated protein kinase cascade that is being explored under several clinical trials as a promising target. Herein, we investigate the catalytic activity in vitro of ASK1 by constructing two mutants: M754T and H729L, from gatekeeper and αC-helix, respectively. Compared to wild type, the mutation of M754T and H729L results in a roughly 3-fold and 2-fold decrease in binding affinity experimentally. In addition, their binding modes with substrate are theoretically predicted and compared by molecular dynamics. Trajectory analyses of simulations indicate that the decrease of binding affinity should be attributed to the loss of H-bond interaction with gatekeeper methionine. Unexpectedly, the conformation of αC-helix in H729L mutant did not alter significantly during the simulations, although the putatively important H-bond with H729 is lost. These simulations showed the regulatory role of H729 in αC-helix is maintained by leucine residue through the interaction with non-polar residues around H729 site.

1320-P: Insulin Receptors and Their Signal Transduction Pathways in Choroid Plexus

The insulin receptor (IR) is a tyrosine kinase receptor present in cell membranes. It is highly expressed in hepatocytes (where it promotes glycogenesis and inhibits gluconeogenesis) , and skeletal muscle and fat (where it facilitates glucose uptake by translocation of the glucose transporter GLUT4) . IR expression is also found throughout the brain, both in neurons and all glial cell types, and for decades impaired insulin signaling has been implicated in the onset and development of Alzheimer’s disease. IR expression pattern in the brain parenchyma is heterogeneous, with highest levels of expression found in olfactory bulb, hypothalamus, and hippocampus. However, the choroid plexus (CP) , a structure present in all 4 ventricles of the brain and responsible for the secretion of cerebrospinal fluid, has the highest affinity for insulin binding compared to any other brain region. This work aims to characterize the insulin signaling in the epithelial cells of the choroid plexus (EChP) and its possible implications in diseases of the brain. Relative expression levels of specific splicing variants of the Insr gene in dissected CP of adult mice were evaluated by qPCR and revealed predominant expression of the variant coding for isoform IR-A when compared to isoform IR-B. In vitro stimulation of EChP with insulin elicits a classical tyrosine kinase cascade, with activation of both the mitogenic (ERK) and metabolic (Akt) arms of the insulin signaling pathway, in a time-and concentration-dependent manner. Using pharmacological (S961, an insulin receptor antagonist) and genetic (insulin receptor shRNA, and Insr cre-loxP) approaches, we show that downregulation of IR in these cells not only impairs insulin signaling, but it also decreases IGF2’s ability to activate ERK and Akt, even when IGF1R levels are unaltered. Finally, using a viral vector coding for an IR shRNA, we show that downregulation of Insr expression in CP of adult mice has a profound effect on its structure, as demonstrated by MRI and histological technique. Disclosure C.Mazucanti: None. V.L.Kennedy: None. A.Cho: None. Q.Liu: None. J.F.O’connell: None. S.Camandola: None. J.M.Egan: None.

Aşılayıcılar için yeni bir eğitim yaklaşımı: İyileştirilmiş kademeli eğitim

Effective training of staff plays a major role in reaching and sustaining immunization goals. Training and updating health staff is the responsibility of all governments and immunization related organizations. The critical issue is finding the most efficient and effective way of providing initial and continuous training. Cascade training is thought to be one of the best methods. However, several researches showed that besides its advantages the classical cascade training approach has some disadvantages. A cascade training strategy is not an inappropriate choice, but the problems are initiated from inappropriate planning and implementation of it. Therefore, in order to have better trained health staff with high performance, rather than thinking of an alternative training strategy, the governments have to consider alternative ways of increasing the quality of the classical cascade training strategy. If the cascade training strategy is well planned, carried out by blending appropriate teaching techniques and is well monitored/supervised during the implementation phase it can be an effective strategy for training the health care staff and managers. In order to differentiate this understanding from the classical cascade approach, the authors propose the “Cascade-Plus Training” model, which is defined as “a well-planned and implemented cascade training strategy with an understanding of a holistic approach to the topic of training, which is practice oriented, flexible, delivered via multiple evidence based training-techniques, supported with effective supervision, monitoring, process evaluation and problem solving deliveries.”

TSPS: A Topic based Shortest Path Set algorithm for influence maximization

This paper focuses on the influence maximization problem in social networks, which aims to find some influence nodes that maximize the spread of information. Most existing achievements usually adopt a uniform propagation probability, without considering the topic information. Moreover, the classic Independent Cascade Model and its approximations have suffered from much running time. To overcome this limitation, this paper proposed a Topic based Shortest Path Set algorithm (TSPS). Additionally, a comprehensive set of experiments are conducted on large real-world networks, showing that our proposal provides more impressive results in the aspects of influence spread and running time.

Southeast Alaskan kelp forests: inferences of process from large-scale patterns of variation in space and time.

Humans were considered external drivers in much foundational ecological research. A recognition that humans are embedded in the complex interaction networks we study can provide new insight into our ecological paradigms. Here, we use time-series data spanning three decades to explore the effects of human harvesting on otter–urchin–kelp trophic cascades in southeast Alaska. These effects were inferred from variation in sea urchin and kelp abundance following the post fur trade repatriation of otters and a subsequent localized reduction of otters by human harvest in one location. In an example of a classic trophic cascade, otter repatriation was followed by a 99% reduction in urchin biomass density and a greater than 99% increase in kelp density region wide. Recent spatially concentrated harvesting of otters was associated with a localized 70% decline in otter abundance in one location, with urchins increasing and kelps declining in accordance with the spatial pattern of otter occupancy within that region. While the otter–urchin–kelp trophic cascade has been associated with alternative community states at the regional scale, this research highlights how small-scale variability in otter occupancy, ostensibly due to spatial variability in harvesting or the risk landscape for otters, can result in within-region patchiness in these community states.

State Feedback Speed Control with Periodic Disturbances Attenuation for PMSM Drive

This paper proposes an auto-tuned constrained state-feedback controller (SFC) to attenuate periodic disturbances present in permanent magnet synchronous (PMSM) motor drives. An online auto-tuning process of SFC has been made using a powerful nature-inspired optimization algorithm—artificial bee colony (ABC)—to achieve high-performance operation of the drive. A novel performance index is proposed to minimize the impact of pulsating torque and obtain smooth-velocity of the drive. The proposed approach is a practical application of classic control theory with novel engineering-tools for improving the operational quality of a PMSM drive system. The obtained results are compared with a classical cascade control structure (CCS) based on proportional-integral (PI) regulators and disturbance observer-based control (DOBC). A detailed time- and frequency-domain analysis has been conducted in respect to periodic disturbances present in a PMSM drive system. Moreover, the robustness of SFC against parameter variations of inductance and resistance has been tested.

Virtual Conductance Based Cascade Voltage Controller for VSCs in Islanded Operation Mode

Voltage source converters have become the main enabler for the integration of distributed energy resources in microgrids. In the case of islanded operation, these devices normally set the amplitude and frequency of the network voltage by means of a cascade controller composed of an outer voltage control loop and an inner current control loop. Several strategies to compute the gains of both control loops have been proposed in the literature in order to obtain a fast and decoupled response of the voltages at the point of common coupling. This paper proposes an alternative and simple methodology based on the introduction of a virtual conductance in the classic cascade control. This strategy allows to design each control loop independently, obtaining a closed-loop response of a first-order system. In this way, the gains of each control loop are easily derived from the parameters of the LC coupling filter and the desired closed-loop time constants. Furthermore, a state observer is included in the controller to estimate the inductor current of the LC filter in order to reduce the number of required measurements. A laboratory testbed is used to validate and compare the proposed controller. The experimental results demonstrate the effectiveness of the proposal both in steady-state and transient regimes.

Simvastatin potentiates the cell-killing activity of imatinib in imatinib-resistant chronic myeloid leukemia cells mainly through PI3K/AKT pathway attenuation and Myc downregulation

Constitutively activated BCR-ABL kinase is considered the driver event responsible in the initiation and development of chronic myeloid leukemia (CML). The advent of the first BCR-ABL inhibitor imatinib has significantly improved the clinical outcome of CML cases. However, resistance to imatinib occurs in 25–30% of CML patients. Due to the lack of effective therapeutic strategies, novel treatment approaches are urgently required for imatinib-resistant CML. Simvastatin, a well-known HMG-CoA reductase inhibitor that confers tremendous clinical benefits in cardiovascular diseases, has attracted mounting attentions for its potent antitumor effects on multiple tumor types. In this study, we demonstrated that simvastatin monotherapy was effective in diminishing cell viability in both imatinib-sensitive and imatinib-resistant CML cells, including T351I mutated cells, with the latter being less vulnerable to the simvastatin than the former. Notably, we found that simvastatin acted as a robust cytotoxic sensitizer of imatinib to kill imatinib-resistant and T315I mutated CML cells in vitro and in vivo. Mechanistically, the cooperative interaction of simvastatin and imatinib was associated with the inactivation of the PI3K/Akt signaling pathway, which was a classical downstream pro-survival cascade of the BCR-ABL kinase. In addition, this drug combination obviously decreased Myc expression through attenuation of canonical Wnt/β-catenin signaling and increased H3K27 trimethylation. Taken together, we provide attractive preclinical results for the combinatorial regimen of simvastatin and imatinib against imatinib-resistant and T315I mutated CML cells. This combined regimens warrants further clinical investigations in patients with imatinib-resistant CML.

Safety, Tolerability, and Clinical Pharmacology of ANX009, an Inhibitory Antibody Fab Fragment Against C1q, Administered Subcutaneously to Healthy Volunteers

Certain autoantibodies that bind to tissue antigens or that deposit in tissues as a component of immune complexes can activate the classical complement cascade, leading to inflammation and tissue damage. As the initiating molecule of the classical complement cascade, C1q is an attractive target for preventing complement activation and its multiple tissue-damaging effects. ANX009 is an antigen binding fragment (Fab) of a humanized antibody against C1q that inhibits C1q substrate interactions and fully blocks activation of all downstream classical complement components. While inhibiting the classical cascade, ANX009 leaves the lectin and alternative complement pathways intact for their normal immune functions. ANX009 is formulated for subcutaneous (SC) administration and is designed for treatment of blood-based and vascular antibody-mediated autoimmune diseases, such as autoimmune hemolytic anemia (AIHA) and lupus nephritis, where complement activation is a key component of disease pathology.A phase 1 first-in-human single ascending dose (SAD) and multiple ascending dose (MAD) study of ANX009 with subcutaneous administration was conducted in 48 healthy volunteers (NCT04535752). Four SAD cohorts were enrolled followed by two MAD cohorts evaluating daily dosing for 7 days or twice weekly dosing x 4 doses. Each cohort had eight participants randomized in a 6:2 active:placebo ratio. Safety and tolerability were assessed, along with serum pharmacokinetics (unbound drug), pharmacodynamics (unbound C1q target), and an ex vivo measure of C1q activity (CH 50 hemolysis of antibody-sensitized sheep red blood cells).All dose levels were well-tolerated. No drug-related safety signals, dose-limiting toxicities, serious adverse events, or adverse events leading to discontinuations were observed. Mild, transient, local injection site reactions were observed.A clear dose-response relationship was observed in SAD cohorts. Negligible reduction in free C1q was observed in the two lowest dose cohorts. A maximum mean reduction in free C1q of 80% was observed at 48 hours post-dose at the third dose level, and full reduction of free C1q through 72 hours was observed at the highest dose level. Similarly, full reduction of free C1q was observed in the MAD cohort with daily dosing as well as in the second MAD cohort with twice weekly dosing. Full reduction of C1q was maintained for 4 days following the last dose in the second MAD cohort. Ex vivo functional activity of C1q was completely inhibited in close correspondence with free C1q levels.Combined safety, tolerability, and clinical pharmacology results from this phase 1 study support advancement of ANX009 to studies in patients with complement-mediated autoimmune disorders. DisclosuresGrover: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Teigler: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Radomile: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Rose: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Yednock: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Keswani: Annexon Inc: Current Employment, Current equity holder in publicly-traded company.

Predator complementarity dampens variability of phytoplankton biomass in a diversity‐stability trophic cascade

Trophic cascades - indirect effects of predators that propagate down through food webs - have been extensively documented in many ecosystem types. It has also been shown that predator diversity can mediate these trophic cascades and, separately, that herbivore biomass can influence the stability of primary producers. However, whether predator diversity can cause cascading effects on the stability of lower trophic levels has not yet been studied. We conducted a laboratory microcosm experiment and a field mesocosm experiment manipulating the presence and coexistence of two heteropteran predators and measuring their effects on zooplankton herbivores and phytoplankton basal resources. We predicted that if the predators partitioned their zooplankton prey, for example by size, then the co-presence of the predators would reduce zooplankton prey mass and lead to (1) increased biomass of, and (2) decreased temporal variability of phytoplankton basal resources. We present evidence that the predators partitioned their zooplankton prey, leading to a synergistic suppression of zooplankton. In turn, this enhanced zooplankton suppression led to only a weak, non-significant increase in the central tendency of phytoplankton biomass, but significantly reduced its variability. Our results demonstrate that predator diversity may indirectly stabilize basal resource biomass via a "diversity-stability trophic cascade," seemingly dependent on predator complementarity, even when there is no significant classic trophic cascade altering the central tendency of biomass. Therefore predator diversity, especially if correlated with diversity of prey use, could play a role in regulating ecosystem stability. This link between predator diversity and producer stability has implications for conservation and for potential biological control methods to improve crop yield reliability.