Downstream Control Research Articles

Control-Oriented Model-Based Reinforcement Learning with Implicit Differentiation

The shortcomings of maximum likelihood estimation in the context of model-based reinforcement learning have been highlighted by an increasing number of papers. When the model class is misspecified or has a limited representational capacity, model parameters with high likelihood might not necessarily result in high performance of the agent on a downstream control task. To alleviate this problem, we propose an end-to-end approach for model learning which directly optimizes the expected returns using implicit differentiation. We treat a value function that satisfies the Bellman optimality operator induced by the model as an implicit function of model parameters and show how to differentiate the function. We provide theoretical and empirical evidence highlighting the benefits of our approach in the model misspecification regime compared to likelihood-based methods.

Time-resolved phosphoproteome and proteome analysis reveals kinase signaling on master transcription factors during myogenesis

SummaryMyogenesis is governed by signaling networks that are tightly regulated in a time-dependent manner. Although different protein kinases have been identified, knowledge of the global signaling networks and their downstream substrates during myogenesis remains incomplete. Here, we map the myogenic differentiation of C2C12 cells using phosphoproteomics and proteomics. From these data, we infer global kinase activity and predict the substrates that are involved in myogenesis. We found that multiple mitogen-activated protein kinases (MAPKs) mark the initial wave of signaling cascades. Further phosphoproteomic and proteomic profiling with MAPK1/3 and MAPK8/9 specific inhibitions unveil their shared and distinctive roles in myogenesis. Lastly, we identified and validated the transcription factor nuclear factor 1 X-type (NFIX) as a novel MAPK1/3 substrate and demonstrated the functional impact of NFIX phosphorylation on myogenesis. Altogether, these data characterize the dynamics, interactions, and downstream control of kinase signaling networks during myogenesis on a global scale.

Analyzing the Water Pollution Control Cost-Sharing Mechanism in the Yellow River and Its Two Tributaries in the Context of Regional Differences

A river basin is a complex system of tributaries and a mainstream. It is vital to cooperatively manage the mainstream and the tributaries to alleviate water pollution and the ecological environment in the basin. On the other hand, existing research focuses primarily on upstream and downstream water pollution control mechanisms, ignoring coordinated control of the mainstream and tributaries, and does not consider the impacts of different environmental and economic conditions in each region on pollution control strategies. This study designed a differential game model for water pollution control in the Yellow River and two of its tributaries, taking regional differences into account and discussing the best pollution control strategies for each region under two scenarios: Nash noncooperative and cost-sharing mechanisms. Furthermore, the factors influencing regional differences in pollution control costs are analyzed, and their impacts on the cost-sharing mechanism of pollution control are discussed. The results show that: (1) The cost-sharing mechanism based on cooperative management can improve pollutant removal efficiency in the watershed and achieve Pareto improvement in environment and economy. (2) The greater the economic development pressure between the two tributaries, the fewer the effects of the cost-sharing mechanisms and the higher the proportion of pollution control costs paid by the mainstream government. (3) Industry water consumption, the proportion of the urban population to the total population at the end of the year, the value-added of secondary sectors as a percentage of regional GDP, the volume of industrial wastewater discharge, and granted patent applications all influence industrial wastewater pollution treatment investment. (4) The greater the coefficient of variation in pollution control costs between the two tributary areas, the less favorable the solution to water pollution management synergy. These findings can help governments in the basin regions negotiate cost-sharing arrangements.

Molecular and Functional Characterization of the Dual‐Specificity Phosphodiesterase Type 10A in Human White Adipocytes

The second messenger cyclic nucleotides cAMP and cGMP are key effectors of thermogenesis in adipocytes in response to a diverse array of cues. Their intracellular levels are normally regulated by the hydrolytic action of phosphodiesterases (PDEs), a conserved superfamily of enzymes composed of 12 families in humans (PDE1‐12) with distinct substrate specificities and tissue distribution profiles. Phosphodiesterase inhibitors are thus promising drugs for the treatment of metabolic disease by promoting cyclic nucleotide‐mediated adipose tissue thermogenesis, but so far mainly those that elevate either cAMP or cGMP signaling alone have been studied. We previously showed that inhibition of the dual‐specificity phosphodiesterase type 10A (PDE10A) with the small molecule drug MP‐10 sufficiently induces a thermogenic gene expression program in differentiated human white pre‐adipocytes (HWP‐ds) to a similar degree as combined cAMP and cGMP treatment. Here, we asked (1) which PDE10A isoforms are expressed in HWP‐ds, (2) the downstream signaling pathways PDE10A controls, and (3) how PDE10A expression is influenced by inflammatory stimuli in this cell type. Immunoblot analysis revealed that both the cytosolic (PDE10A1) and membrane‐bound (PDE10A2) isoforms of PDE10A are highly expressed in HWP‐ds, predominantly in the former subcellular compartment. This was confirmed by fractionation and immunofluorescence analyses. Inhibition of PDE10A with MP‐10 dose‐dependently increased PKA and PKG signaling as revealed by phosphorylation of cyclic response element binding protein (CREB) and vasodilator‐stimulated phosphoprotein (VASP) at S133 and S239, respectively. Consistently, the stimulation of lipolysis by MP‐10 was fully prevented by combined pre‐incubation of HWP‐ds with selective PKA and PKG inhibitors. Finally, mimicking the adipose tissue microenvironment in obesity by applying pro‐inflammatory cytokines onto HWP‐ds caused an early (4‐hour) and sustained (24‐hour) increase in PDE10A mRNA expression. These results provide new insight into the molecular character, function, and regulation of PDE10A in human adipocytes and further justify the use of selective inhibitors for the treatment of metabolic disease through stimulating adipose tissue thermogenesis in a more efficient and targeted manner.

Dynamic Control of Water Level in Flood Limited Reservoir Based on Intelligent Calculation

Determining the flood-limited water level is the focus of the contradiction between flood control and profit-making. The dynamic control of the flood-limited water level of the reservoir is an effective way to ensure flood control safety and realize flood resource utilization. Based on the analysis of the availability of forecast information, this paper conducts a study on the dynamic control of the flood-limited water level in Panjiakou Reservoir. The dynamic control area of Panjiakou Reservoir is determined by the “predischarge capacity constraint method.” On the premise of satisfying the flood control safety of the reservoir, the “prestorage and predischarge method” is adopted according to the real-time forecast information, the water conditions, work conditions, disaster conditions, etc. to develop a dynamic control plan for the flood-limited water level in the main flood season of the reservoir. Finally, based on the improved first-order second moment method (AFOSM), the dispatch risk model of the dynamic control of the flood-limited water level of the reservoir is constructed, and the risk analysis of the flood forecasting system is carried out. The results show that (1) the flood forecast accuracy of Panjiakou Reservoir conforms to the standard of the B-level forecasting scheme, and the results can be applied under the condition of considering the forecast error; (2) it is suggested that the maximum water level of the Panjiakou Reservoir in the main flood season is dynamically controlled to be 218 m. In the case of water supply guarantee rate P = 75 % , compared with the current situation of the flood-limited water level of 216 m, the water supply is increased by 40 million m3, and the flow of electricity is increased by 30 million. The flood control risk rate under the rain leakage error is lower than 0.1, which is the minimum risk level, which is acceptable. However, when the net rain leakage error is greater than 25 mm, there may be insufficient leakage or excessive leakage, which will cause inconvenience to downstream flood control.

Joint flood control scheduling strategy of large cascade reservoirs: A case study of the cascade reservoirs in the upper reaches of the Yangtze River in China

AbstractThe flood control ability of cascade reservoirs is affected by many factors, such as the inflow flood form, and flood control scheduling rules. When large cascade reservoirs were built, it is necessary to evaluate the overall flood control ability of the reservoirs and explore the best joint scheduling strategy. In this study, cascade reservoirs in the upper reaches of the Yangtze River in China were selected as the research case. A stochastic model of inflow floods and a dynamic capacity flood regulation model for the Three Gorges Reservoir (TGR) were established, and the most dangerous inflow floods for downstream flood control were generated. Different scheduling strategies for the cascade reservoirs were set to block the TGR inflow flood to explore the flood control risk in the Jingjiang area under joint operation of the TGR and the upstream cascade reservoirs. The research results show that the joint flood control scheduling strategy has a huge impact on the flood control ability of cascade reservoirs, and different scheduling schemes must be adopted according to the inflow flood characteristics of the reservoirs. This study provides a new idea for systematically evaluating the flood control ability of large cascade reservoirs and selecting appropriate scheduling strategies.

Power Inspection Design by Internet of Things and RFID Technology in Smart City

As the basic element and module unit in the construction architecture of smart city, the Internet of things (IoT) is also the key foundation and important support for realizing "automatic perception, rapid response, and scientific decision-making" of smart city. The study aims to improve the efficiency of power inspection in power enterprises and provide intelligent technology for power inspection. After the theoretical analysis of IoT and RFID technology under the background of smart city, the study discusses the information acquisition principle of RFID technology. Second, based on IoT and smart grid, the study takes the power equipment of power company A as an example, and puts forward the power inspection scheme, including the information required for inspection and the inspection of primary and secondary equipment. The specific contents are as follows: health assessment is carried out according to the real-time alarm of power equipment, and the control command is sent to the downstream control equipment to confirm the alarm information. Meantime, based on the alarm information of power equipment and related equipment, the expert analysis system is used for reasoning and analysis, and the RFID tag is used to supervise the inspectors to arrive at the site and inspect the situation according to the predetermined route. The temperature of the cable of power company A is measured under normal and hidden dangers, and the body insulation test is conducted on No. 1 main transformer. The results show that under normal operation, the cable temperature at each point is slightly different, which is basically about 40 °C. The temperature before the fourth point of the cable rises obviously, indicating that the fourth point has faulty. Over time, the more chemical molecules are detected in phase A. When phase B and phase C are tested on the same day, the difference of chemical molecular content is relatively small. It indicates that the chemical molecular content detected by chromatographic test of bulk insulating oil is normal. To sum up, smart power, as the objective need of urban intelligent development, is an important foundation of smart city. The power inspection scheme based on IoT and RFID technology proposed has high detection efficiency.

Impacts of reservoir operation and urbanization on flood inundation in the Vu Gia Thu Bon Basin, Vietnam

Abstract This study examines the effects of upstream reservoir operation and urbanization on flood inundation in the Vu Gia Thu Bon river basin. The alternative reservoir operation strategies corresponding to the flood storage capacity (Vpl) of 10, 20, and 30% of the active storage capacity (Vhi) are evaluated and compared with the prevailing inter-reservoir operation procedure in terms of inundation effects. The results reveal that increasing the Vpl from 10% to 30% of the Vhi reduces the flooded area by 11.8% and lowers the water level at downstream stations from 6% to 30%. The government's procedure is considered safe to supply water, but the inundation duration is longer, resulting in more damage than the scenario of Vpl=20%Vhi. Regarding urbanization, the expansion of newly urbanized areas has resulted in increased flooding in their surrounding areas, with an increase in flood depth of more than 3 m. Moreover, the new roads have reduced the capacity of flood drainage and caused severe flooding. The water level difference between the two sides of the road can be as high as 2 m. This research will assist managers in developing and implementing appropriate downstream flood control measures.

OPERATION OF MOSUL – DOKAN RESERVOIRS AND SAMARRA BARRAGE USING HEC – RES.SIM MODEL DURING FLOOD PERIOD

Major dams on Tigris River were designed and constructed as multi – purposes reservoirs. Since the flood event may occur for a specified period of the year, simulation model could be developed for rapid release decision according to time series reservoir inflow. This study deals with the application of HEC – ResSim version 3.1 in order to simulate and evaluate the behavior of the reservoirs system represented by Mosul, Dokan reservoirs, and Samarra barrage during the flood period 1987-1988 which is considered as a flood period. The release function of date was applied as an operating rule in order to provide safety reservoir storage accompanied with downstream release control. The results obtained from simulation of operating alternatives had been compared with the historical recorded data for the same time of simulation period, and exhibit flood control caused by specifying reservoir outflow with an appropriate limits yields appreciable matching between reservoirs' rule curves and computed pool elevation for both reservoirs. The simulation plots revel the ability of the existing projects to assist in sizing flood risk during flood event, and the storage level in the reservoirs reached a suitable elevation according to the time period of inflow, storage, and release values with the ability of Samarra barrage to divert excess flood water towered Tharthar Lake.

Multidecadal Trends in Organic Carbon Flux Through a Grassland River Network Shaped by Human Controls and Climatic Cycles

AbstractGrasslands are among the most disturbed systems on Earth due to extensive agricultural development and river regulation. To define how these factors impact the movement of carbon (C) through river networks, we quantified multi‐decadal, seasonal patterns of dissolved organic C (DOC) fluxes through a grassland river network. Despite urbanization and effluent release in recent decades, we did not observe trends in DOC fluxes over 20 to 40 year monthly sample records. High interannual variability in DOC flux was linked to climate teleconnections, most strongly the Pacific Decadal Oscillation. Human impacts were more apparent on the seasonality of flux, since spring export dominated DOC flux in most sub‐watersheds, but seasonal changes were absent at the river mouth due to downstream flow control. In grassland regions, human impacts on DOC flux are complex, and subtle long‐term changes may be difficult to identify in contemporary monitoring records due to increasing hydro‐climatic variability.

Large-eddy simulation of split injection strategies in RCCI conditions

In this study, we investigate the effect of different split injection strategies on ignition delay time (IDT) and heat release rate (HRR) characteristics in Reactivity Controlled Compression Ignition conditions via large-eddy simulation and finite-rate chemistry. A diesel surrogate (n-dodecane) is injected into a domain with premixed methane and oxidiser in two separate injection pulses. Three different split injection strategies are investigated by fixing the amount of total fuel mass: varying the first injection timing, varying the second injection timing, and changing the fuel mass ratio between the two injections at a fixed injection timing. A compression heating mass source term approach is utilised to take compression heating into account. The main findings of the study are as follows: (1) In general, the IDT shifts towards the top-dead centre when the first injection is advanced or the second injection is retarded. The size and spatial pattern of the ignition kernels are shown to depend on the dwell time between the injections. (2) A precisely timed first injection offered the best control over ignition and HRR characteristics. However, advancing the first injection may lead to over-dilution downstream, preventing volumetric ignition and reducing the peak HRR value. (3) Approximately 21% decrease in the maximum HRR value, as well as a factor of 2.8 increase in combustion duration could be achieved by advancing the first injection timing. (4) As indicated by frozen-flow chemistry analysis, in the investigated configurations, the reactivity stratification is controlled by mixture stratification rather than temperature. The findings indicate that the first injection controls the downstream reactivity stratification, offering ignition and HRR control.

Impacts of Removal Compensation Effect on the Mercury Emission Inventories for Nonferrous Metal (Zinc, Lead, and Copper) Smelting in China.

Nonferrous metal smelting (NFMS) is one of the key sources of mercury (Hg) emissions to the air and cross-media Hg transfer in China. In this study, a "Hg removal compensation effect" between upstream and downstream air pollution control devices (APCDs) in NFMS was uncovered based on the investigation of field test data. The relationships between the Hg concentration in flue gas and the Hg removal efficiencies of typical APCDs were established, and an advanced probabilistic mass flow model regarding this effect was developed. Model comparison shows that the probabilistic essence of the advanced model prevents the underestimation of the deterministic model caused by using the geometric means of the Hg contents of metal concentrates, and the consideration of the removal compensation effect leads to more accurate estimation of the overall Hg removal efficiency of cascaded APCDs. The Hg emission abatement in the NFMS sector from 2010 to 2017 was evaluated to be 55.6 t, which was 13.5% higher than the estimate without considering the Hg removal compensation effect. The overall uncertainty of the improved model was reduced. This study provides a new methodology for more accurate evaluation of the effectiveness of the national implementation plan for the Minamata Convention on Mercury.

Application of an Optimization/Simulation Model for the Real-Time Flood Operation of River-Reservoir Systems with One- and Two-Dimensional Unsteady Flow Modeling

An application is presented of a new methodology for the real-time operations of river-reservoir systems. The methodology is based upon an optimization/simulation modeling approach that interfaces optimization with a one and/or two-dimensional unsteady flow simulation model (U.S. Army Corps of Engineers HEC-RAS). The approach also includes a model for short-term rainfall forecasting, and the U.S. Army Corps of Engineers HEC-HMS model for rainfall-runoff modeling. Both short-term forecasted rainfall in addition to gaged streamflow data and/or NEXRAD (Next-Generation Radar) can be implemented in the modeling approach. The optimization solution methodology is based upon a genetic algorithm implemented through MATLAB. The application is based upon the May 2010 flood event on the Cumberland River system in the USA, during which releases from Old Hickory dam caused major flooding in the downstream area of Nashville, TN, USA, and allowed the dam to be placed in an emergency operational situation. One of the major features of the modeling effort and the application presented was to investigate the use of different unsteady flow modeling approaches available in the HEC-RAS, including one-dimensional (1D), two-dimensional (2D), and the combined (1D/2D) approach. One of the major results of the application was to investigate the use the different unsteady flow approaches in the modeling approach. The 2D unsteady flow modeling, based upon the diffusion wave approach, was found to be superior for the application to the Cumberland River system. The model application successfully determined real-time operations that would have maintained the flood water surface elevations at the downstream control point in Nashville below the 100-year return period river water surface and maintaining the gate openings at the Old Hickory Dam from reaching an emergency operational situation, which could have caused major losses at the dam.

Stent Strategy in Bile Leakage after Liver Surgery

Introduction: Endoscopic retrograde cholangiopancreatography (ERCP) with stenting is considered the treatment of choice in bile leakage (BL) after liver surgery. Evidence is lacking on which strategy to choose, distal downstream decompression of the biliary tree or insertion of a longer stent for drainage closer to or bridging the the leakage point. Methods: All ERCPs performed in Sweden are registered in a national quality registry (GallRiks). Data on all ERCPs performed for the indication of BL between 2006-2017 were extracted. Patients who underwent endoscopic intervention for BL following liver resection were compared in two groups: sphincterotomy only or placement of a stent ≤ 7 cm (distal decompression) vs. placement of a stent >7cm (proximal drainage or bridging). The primary outcome was was cessation of BL within 30 days of endoscopic intervention. Results: A total of 2346 ERCPs were performed for BL, of which 259 procedures were in 201 persons following liver resection. Ten patients in whom ERCP could not demonstrate a leak were excluded from the analyses. In 87 patients distal decompression was performed and in 104 patients proximal drainage or bridging. The groups were comparable regarding age, sex and comorbidities. There were no differences in 30-day cessation of BL between the two groups (OR 0.71 (95% CI 0.26-1.98)) and complication rates were comparable (OR 1.30 (95% CI 0.73-2.31). Conclusion: Downstream control seems to be as efficient as the insertion of a proximal or bridging stent in treatment of BL after liver resection.

Optimal operation of multi-reservoir system for flood control and hydroelectric generation

In this research, a flood control operating strategy is developed based on a simulation-optimization model to reduce flood damage downstream of multi-reservoir systems by using spillway gates. For this purpose, an optimization algorithm is introduced, in which the maximum water level of the downstream control points and hydropower potential generation in the flood season are objective functions, and the level of the stages of spillway gates are the decision variables. A global optimization tool, Shuffled Complex Evolution (SCE) algorithm implemented in the AUTOCAL software was coupled with the Mike 11 from DHI simulation model for optimizing stages level of spillway gates. As a case study, the Vu Gia Thu Bon rivers catchment including multi-reservoirs of A Vuong, Song Tranh 2, Dak Mi 4 and Song Bung 4 is analyzed. The proposed method was demonstrated to provide an effective tradeoff between flood control and hydropower generation.

ASSESSMENT OF WATER COLLECTED FROM BOREHOLES WITHIN UNSANITARY LANDFILL IN ANAMBRA STATE

Leachate infiltration from indiscriminate dumping of refuse has been a course of concern to the public. These leachates are a source of organic or inorganic pollutants to the underground water which poses health-associated risks to the public. The present study aims to determine the physicochemical properties and quality levels of boreholes located within the unlined dumpsite environment. Thirty-two borehole samples (sixteen upstream and sixteen downstream samples) were collected within the dumpsite environment. The upstream samples are closer to the dumpsite, while the downstream(control) is far away from the dumpsite. The physicochemical parameters were assessed using American Public Health Association standard methods. The quality of the boreholes was compared using the WHO allowable threshold. The result revealed that nitrites, chemical oxygen demand, and biochemical oxygen demand values exceeded the WHO drinking water limits for both locations which can constitute environmental and public health problems. The upstream sample's physicochemical characteristics values were greater than the downstream samples based on its closeness to the landfill.  The seasonal variation revealed that the wet season values were significantly greater than the dry season values due to the percolation of leachates from the dumpsite during the rainy season. It is concluded that indiscriminate dumping of refuse using unlined dumpsite practices within the residential neighbourhood can damage the environment and induce public health risks of the residents.

Identification of Flood-prone Areas using HEC-HMS and HEC-RAS, the Case of Ciberang River Basin, Lebak District of Banten Province

It is common practice that flood hydrograph simulations help to provide better flood prediction and flood damage reduction planning. These efforts require information on flood-prone areas identification from the hydrological and hydraulic analysis results. Historically, the Ciberang River Basin has experienced floods. Those floods cause the loss of human life and damage some houses along the river’s channels, especially in Lebak District, Banten Province, Indonesia. The main objective of this study is to identify flood-prone areas based on the simulation result of a hydrologic and hydraulic model of catchment response due to several extreme rainfall events using HEC-HMS and HEC-RAS software. Rainfall and discharge data measured at the Ciberang-Sabagi water level gauge on 10 January 2013 were used to calibrate hydrological watershed parameters. The hydraulics channel routing is started from the planned location of the Sabo dam to the downstream control point. The next stage was the simulation of rainfall-runoff transformation and 1D unsteady flow channel routing for the 2, 5, and 10-years floods return periods. The main result of this study is a flood hazards map that shows the spatial distribution of the area and inundation depth for each return period of the flood.

Autocyclic (avulsion‐induced) base‐level change, its upstream and downstream controls, and effects on floodbasin sedimentation: The 1870s avulsion of the Saskatchewan River, Cumberland Marshes, Canada

AbstractThis study examines centennial‐scale hydrological and sedimentological effects of floodplain inundation by avulsion and its upstream and downstream controls. The 1870s avulsion in Cumberland Marshes diverted the Saskatchewan River flow towards Cumberland Lake, a local base level. It invaded a poorly drained sub‐basin of Cumberland Marshes floodplain linked to the parent Saskatchewan River by two small outlets in the resistant substrate. The rapid increase in inflow (~5× on average) during the earlier stages of the avulsion resulted in the base‐level rise and floodplain inundation by the avulsion lake. Since the early 20th century, the forced regression of the avulsion lake occurred, caused by ~5× outlet channel enlargement by ‘hungry‐water’ outflows, whereas the mean lake inflows experienced little change. The avulsion lake served as an effective sediment trap and was filled by predominantly progradational sandy and silty avulsion deposits up to 3–4 m thick, covering about 700 km2. Elsewhere, fluviodeltaic settings with ‘negative relief’ and limited hydrologic connectivity with the rest of the floodplain may be prone to avulsion lakes that form if the rates of inflow increased by avulsion exceed the rates of outflow. Avulsion lakes can last for ~100 years or more before they drain and/or become filled by overbank sediments. On well‐drained floodplains, inundations by avulsions are expected to be short‐term and result in little progradational deposition. This study demonstrates that in some local hydrographic basins, base level becomes a variable of an evolving avulsion rather than its fixed external control. Although avulsion‐induced base‐level changes are short‐lived, they affect 102–103 km2 of a floodplain and occur rapidly, accompanied by high aggradation rates.

Evaluation of Drainage Water Detention Efficiency of Off-Line Ditch-Pond Systems and Its Influencing Factors

Ditch-pond systems can effectively alleviate the adverse effects of agricultural drainage on downstream canals and flood control in downstream areas. In this study, peak flow reduction rate (PFR) and drainage volume detention rate (DVD) are used to evaluate the effectiveness of an off-line ditch-pond system for reducing peak flow, retarding agricultural drainage water, and examining the key influencing factors. The results show that the PFR and DVD of the off-line ditch-pond system are significantly affected by three parameters: weir depth (Ld), weir width (Lw), and pond area-to-drainage area ratio (Ksp). Both the PFR and DVD increase with the increase in Ld, Lw, and Ksp. The effects of Ld and Lw on the PFR and the DVD are significant, whereas that Ksp is relatively small. Adjusting Ld and Lw increases both the PFR and DVD up to 80%. Specifically, Ld contributes 75% of the variations in the PFR and the DVD, and Lw affects only 17% of the PFR variations and 11% of the DVD variations. These findings confirm that an off-line ditch-pond system can be effectively used for the detention of agricultural drainage water. Thus, when such a system is designed with an appropriate diversion weir, the impact of agricultural drainage water on downstream canals and downstream areas can be reduced remarkably.

Impact of emotionally-charged images and trial order on downstream cognitive processing: An ERP study

Theories of emotion-cognition interactions suggest that emotional valence can both facilitate or limit cognitive performance. One cause for the mixed findings may be the order (random versus non-random presentation) in which emotional stimuli are presented. To investigate the impact of stimuli order on cognitive control processing, EEG data were recorded as 130 undergraduate students (M age = 22.2, SD = 5.4; 79 female) completed a modified version of the AX-Continuous Performance Task in which the cue was followed by an emotionally-valenced image (positive, negative, and neutral). Specifically, the task was designed so that valenced images were presented in either a block or random order, prior to probe presentation. We examined two event-related potentials (ERPs), the N2, which reflects aspects of cognitive control, and the late positive potential (LPP), which reflects attention allocation to emotional stimuli. We assessed the impact of emotionally oriented attention (LPP) on downstream cognitive control (N2) and how this relationship might differ for a block versus random (order of emotional image) task design. Consistent with the LPP literature, we found a main effect of image valence with the negative trials showing larger LPPs than the positive and neutral trials. For N2s, we found that the negative trials were associated with smaller N2s than both the positive and neutral trials. We observed that as LPP amplitude increased, subsequent N2 amplitude was reduced, specifically for negative trials in the random design. These results suggest an emotion-related depletion of neural cognitive resources. Lastly, we found larger N2s for the block design versus the random design. Together, these results indicate the importance of paying attention to both trial order (block versus random) and within trial stimulus sequence when designing emotion induction tasks.