35 research outputs found
Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways
It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers
Modeling the vacuolar storage of malate shed lights on pre- and post-harvest fruit acidity
Background: Malate is one of the most important organic acids in many fruits and its concentration plays a critical role in organoleptic properties. Several studies suggest that malate accumulation in fruit cells is controlled at the level of vacuolar storage. However, the regulation of vacuolar malate storage throughout fruit development, and the origins of the phenotypic variability of the malate concentration within fruit species remain to be clarified. In the present study, we adapted the mechanistic model of vacuolar storage proposed by Lobit et al. in order to study the accumulation of malate in pre and postharvest fruits. The main adaptation concerned the variation of the free energy of ATP hydrolysis during fruit development. Banana fruit was taken as a reference because it has the particularity of having separate growth and post-harvest ripening stages, during which malate concentration undergoes substantial changes. Moreover, the concentration of malate in banana pulp varies greatly among cultivars which make possible to use the model as a tool to analyze the genotypic variability. The model was calibrated and validated using data sets from three cultivars with contrasting malate accumulation, grown under different fruit loads and potassium supplies, and harvested at different stages. Results: The model predicted the pre and post-harvest dynamics of malate concentration with fairly good accuracy for the three cultivars (mean RRMSE = 0.25-0.42). The sensitivity of the model to parameters and input variables was analyzed. According to the model, vacuolar composition, in particular potassium and organic acid concentrations, had an important effect on malate accumulation. The model suggested that rising temperatures depressed malate accumulation. The model also helped distinguish differences in malate concentration among the three cultivars and between the pre and post-harvest stages by highlighting the probable importance of proton pump activity and particularly of the free energy of ATP hydrolysis and vacuolar pH. Conclusions: This model appears to be an interesting tool to study malate accumulation in pre and postharvest fruits and to get insights into the ecophysiological determinants of fruit acidity, and thus may be useful for fruit quality improvement. (Résumé d'auteur
Anti-windup strategy for an LQ current controller with oscillatory terms for three-phase grid-tie VSCs in SMES systems
The paper presents a linear-quadratic current controller with damped oscillatory terms designed for three-phase grid-tie voltage source converters used in SMES systems and operated under distorted grid voltage conditions. Special emphasis is placed on a synthesis of an anti-windup mechanism to prevent wind-up derived from the oscillatory terms by the use of a new active damping loop based on a simple moving average method. As a consequence, the current feedback gain may be increased without unwanted overshoot and overruns, and performance of the system can be improved
Grid-tied converter operated under unbalanced and distorted grid voltage conditions
The paper presents a three-phase grid-tied converter operated under unbalanced and distorted grid voltage conditions, using a multi-oscillatory current controller to provide high quality phase currents. The aim of this study is to introduce a systematic design of the current control loop. A distinctive feature of the proposed method is that the designer needs to define the required response and the disturbance characteristic, rather than usually unintuitive coefficients of controllers. Most common approach to tuning a state-feedback controller use linear-quadratic regulator (LQR) technique or pole-placement method. The tuning process for those methods usually comes down to guessing several parameters. For more complex systems including multi-oscillatory terms, control system tuning is unintuitive and cannot be effectively done by trial and error method. This paper proposes particle swarm optimization to find the optimal weights in a cost function for the LQR procedure. Complete settings for optimization procedure and numerical model are presented. Our goal here is to demonstrate an original design workflow. The proposed method has been verified in experimental study at a 10 kW laboratory setup
System napędowy z magazynowaniem energii pomocniczej oparty na ultrakondensatorze dla miejskiego akumulatorowego pojazdu elektrycznego
This paper presents a powertrain system for an urban electric vehicle. The powertrain system consists of a hybrid energy source (battery storage and ultracapacitors) and drivetrain system (two in-wheel outer-rotor PMSM motors). Battery performance improvement, has been achieved by supporting it with ultracapacitor energy storage. Power flow control using fuzzy logic controller is presented in detail. An electronic differential algorithms have been implemented and tested.W artykule przedstawiono układ napędowy dla miejskiego pojazdu elektrycznego. Układ napędowy składa się z hybrydowego źródła energii (akumulatory i ultrakondensatory) i systemu napędowego (dwa silniki w-kołach o zewnętrznym wirniku PMSM). Osiągnięto poprawę wydajności akumulatora poprzez wspieranie go magazynowaniem energii przez ultrakondensator. Przedstawiono w szczegółach sterowanie przepływem mocy z wykorzystaniem regulatora logiki rozmytej. Elektroniczne algorytmy różnicowe zostały wdrożone i przetestowane
Power Electronic Drive System for an Urban Electric Vehicle with a Hybrid Energy Storage — The Physical Emulator and the Mobile Mockup
This paper describes the design, construction and commissioning of compact converters for an urban electric vehicle. The proposed powertrain consists of two in-wheel outer-rotor motors, three-level inverters and interleaved converters interfacing the battery and the ultracapacitors. The electronic differential with the Ackermann steering model has been tested using a non-mobile experimental setup. A fuzzy logic controller for the onboard hybrid energy source is developed and discussed. Simulation studies point out the possibility to use slope information from the navigation system to improve performance of the source. This part of the research has been validated through extensive simulation tests on the real driving cycles. A mobile mockup is currently under the development and the algorithm is going to be the subject of future field tests.W artykule przedstawiono opis konstrukcji oraz testy kompaktowych przekształtników energoelektronicznych przeznaczonych dla miejskiego pojazdu elektrycznego. Zaproponowany układ napędowy składa się z dwóch silników umieszczonych w kołach, trójpoziomowych falowników napięciowych i przekształtników DC/DC współpracujących z magazynem bateryjnym i ultrakondensatorowym. Na laboratoryjnym stanowisku badawczym wykonano testy dyferencjału elektronicznego wykorzystującego model Ackermanna. Zaproponowano również regulator fuzzy logic do zarządzania mocą w hybrydowym źródle energii. Badania symulacyjne wykazały zasadność wykorzystania w regulatorze informacji o nachyleniu terenu (np. z systemu GPS) do poprawy wydajności źródła. Algorytm będzie przedmiotem przyszłych badań na makiecie mobilnej, która aktualnie jest w trakcie budowy
An electric vehicle powertrain with a hybrid battery and ultracapacitor energy storage for urban areas
This paper presents a four-motor drive system designed within the frame of ECO-Mobility Project (ECO-Car subtask). A flexible non-mobile experimental set-up with an ultracapacitor energy storage for 2WD electric car powertrains testing is under development. Proposed topology with an active grid converter will allow to simulate electrochemical battery with any desired characteristics. This in turn will enable various experiment scenarios in terms of battery cells quality, wear level and thermal conditions. Our next target is to design a powertrain (power converters and controllers) for a mobile mockup, incl. an auxiliary energy storage and a converter that interfaces a LiFePO4 battery pack. A control strategy for the hybrid onboard energy storage is presented in detail. Some decisions concerning system functionality are discussed. A mobile mockup is also under construction. The proposed vehicle has been designed as a city car suitable equally for disabled, elderly and fit people
Targeting cyclooxygenase-2 in depression is not a viable therapeutic approach and may even aggravate the pathophysiology underpinning depression
Depression is a complex progressive disorder accompanied by activation of inflammatory and Th-1 driven pathways, oxidative and nitrosative stress (O&NS), lowered antioxidant levels, mitochondrial dysfunctions, neuroprogression and increased bacterial translocation. In depression, activation of immuno-inflammatory pathways is associated with an increased risk for cardio-vascular disorder (CVD). Because of the inflammatory component, the use of cyclooxygenase 2 (COX-2) inhibitors, such as celecoxib, has been advocated to treat depression. Electronic databases, i.e. PUBMED, Scopus and Google Scholar were used as sources for this selective review on the effects of COX-2 inhibitors aggravating the abovementioned pathways. COX-2 inhibitors may induce neuroinflammation, exacerbate Th1 driven responses, increase lipid peroxidation, decrease the levels of key antioxidants, damage mitochondria and aggravate neuroprogression. COX-2 inhibitors may aggravate bacterial translocation and CVD through Th1-driven mechanisms. COX-2 inhibitors may aggravate the pathophysiology of depression. Since Th1 and O&NS pathways are risk factors for CVD, the use of COX-2 inhibitors may further aggravate the increased risk for CVD in depression. Selectively targeting COX-2 may not be a viable therapeutic approach to treat depression. Multi-targeting of the different pathways that play a role in depression is more likely to yield good treatment results. <br /