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1
Ford, J. J., H. Bevrani, and G. Ledwich. "Adaptive load shedding and regional protection." International Journal of Electrical Power & Energy Systems 31, no. 10 (November 2009): 611–18. http://dx.doi.org/10.1016/j.ijepes.2009.06.004.
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Mahesh, C., F. T.Josh, and A. Sanjeevi Gandhi. "A comprehensive study on protection, control and communication techniques: a key concept for microgrid intelligent operation." International Journal of Engineering & Technology 7, no. 2.8 (March 19, 2018): 35. http://dx.doi.org/10.14419/ijet.v7i2.8.10320.
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Microgrid is an integrated network of renewable and non renewable resources to supply the green power to a small range of community. An effective communication technology is necessary to be implemented among the power generations, storages and loads of microgrid in order to manage the load sharing, shedding and protection issues. This paper provides the study on architecture, characteristics, load managements, protection schemes, communication techniques and research challenges of microgrid.
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Huang, Chin-Chyr, and Shyh-Jier Huang. "A time-based load shedding protection for isolated power systems." Electric Power Systems Research 52, no. 2 (November 1999): 161–69. http://dx.doi.org/10.1016/s0378-7796(99)00019-x.
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Siyanda Mnguni, Mkhululi Elvis, and Yohan Darcy Mfoumboulou. "An approach for a multi-stage under-frequency based load shedding scheme for a power system network." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 6 (December 1, 2020): 6071. http://dx.doi.org/10.11591/ijece.v10i6.pp6071-6100.
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The integration of load shedding schemes with mainstream protection in power system networks is vital. The traditional power system network incorporates different protection schemes to protect its components. Once the power network reaches its maximum limits, and the load demand continue to increase the whole system will experience power system instability. The system frequency usually drops due to the loss of substantial generation creating imbalance. The best method to recover the system from instability is by introducing an under-frequency load shedding (UFLS) scheme in parallel with the protection schemes. This paper proposed a new UFLS scheme used in power systems and industry to maintain stability. Three case studies were implemented in this paper. Multi-stage decision-making algorithms load shedding in the environment of the DIgSILENT power factory platform is developed. The proposed algorithm speeds-up the operation of the UFLS scheme. The load shedding algorithm of the proposed scheme is implemented as a systematic process to achieve stability of the power network which is exposed to different operating conditions. The flexibility of the proposed scheme is validated with the modified IEEE 39-bus New England model. The application of the proposed novel UFLS schemes will contribute further to the development of new types of engineers.
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Hajar, Ibnu, and Muhammad Ridho. "Review dan Resetting Skema Overload Shadding Interbus Transformer 500/150 kV 1,3 Gandul dan 2 Kembangan." Energi & Kelistrikan 12, no. 1 (June 30, 2020): 32–42. http://dx.doi.org/10.33322/energi.v12i1.942.
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Power system protection is one of the most important aspect in power system operation. Power system protection is an attempt to widely prevent the fault over the whole system. One of the power system protection schemes that have been applied by PT. PLN (Persero) to 150 kV Jawa Bali subsystem is Over Load Shedding of Interbus Transformer 500/150 kV. Over Load Shedding scheme has correctly to be set to prevent overload on secondary side of IBT 500/150 kV. Black Out occured on January 2, 2018 at 150 kV subsystem of 1,3 Gandul – 2 Kembangan – Muara Karang is one of the impact caused by incorrect-setting of Over Load Shedding scheme. The purposes of this research are to review the initial setting of Over Load Shedding scheme and to reset it as a follow-up of Black Out event occured in this subsystem. This research uses qualitative method by analyzing the overload points obtained by the simulation of DIgSILENT 14.3.1. This thesis results the new Over Load Scheme setting of IBT 500/150 kV 1 and 3 Gandul those are 3 seconds of pick-up times for the first step and 3,5 seconds of pick-up times for the second step wherein 410,98 MW is necessarily to be shed in 2 steps. Meanwhile, the new Over Load Shedding setting of IBT 500/150kV 2 Kembangan are 2 seconds of pick-up times for the first step and 2,5 seconds of pick-up times for the second step wherein 378,23 MW is necessarily to be shed in 2 steps.
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Hoseinzadeh, Bakhtyar, and Claus Leth Bak. "Centralized coordination of load shedding and protection system of transmission lines." International Transactions on Electrical Energy Systems 29, no. 1 (August 6, 2018): e2674. http://dx.doi.org/10.1002/etep.2674.
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Skrjanc, Tadej, Rafael Mihalic, and Urban Rudez. "Principal Component Analysis (PCA)-Supported Underfrequency Load Shedding Algorithm." Energies 13, no. 22 (November 12, 2020): 5896. http://dx.doi.org/10.3390/en13225896.
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This research represents a conceptual shift in the process of introducing flexibility into power system frequency stability-related protection. The existing underfrequency load shedding (UFLS) solution, although robust and fast, has often proved to be incapable of adjusting to different operating conditions. It triggers upon detection of frequency threshold violations, and functions by interrupting the electricity supply to a certain number of consumers, both of which values are decided upon beforehand. Consequently, it often does not comply with its main purpose, i.e., bringing frequency decay to a halt. Instead, the power imbalance is often reversed, resulting in equally undesirable frequency overshoots. Researchers have sought a solution to this shortcoming either by increasing the amount of available information (by means of wide-area communication) or through complex changes to all involved protection relays. In this research, we retain the existing concept of UFLS that performs so well for fast-occurring frequency events. The flexible rebalancing of power is achieved by a small and specialized group of intelligent electronic devices (IEDs) with machine learning functionalities. These IEDs interrupt consumers only when the need to do so is detected with a high degree of certainty. Their small number assures the fine-tuning of power rebalancing and, at the same time, poses no serious threat to system stability in cases of malfunction.
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Wang, Heng. "Overload Control Strategy Based on Triangular Fuzzy Analytic Hierarchy Process." E3S Web of Conferences 256 (2021): 02019. http://dx.doi.org/10.1051/e3sconf/202125602019.
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After the high-voltage transmission line is cut off due to a fault, the bearing transmission power will be transferred, which may cause overload. If overload cannot be eliminated quickly and scientifically, it is very likely that the line backup protection will be activated, which will trigger chain trip or even blackout accidents. In view of this, this paper proposed a cross-voltage level optimization load shedding control strategy based on fuzzy analytic hierarchy process. Through step-by-step progression in the three indexes of line overload degree, load importance degree, and unit load shedding cost, the lower-level lines of the overload line are selected for optimal line removal, thus achieving the goal of optimizing load shedding across voltage levels.
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Pereira Fe, Luiz Augusto, Alexandre Rocco, Heraldo Silveira B, and Geraldo Caixeta Gu. "Electric Power System Under-Voltage Load Shedding Protection Can Become a Trap." American Journal of Applied Sciences 6, no. 8 (August 1, 2009): 1526–30. http://dx.doi.org/10.3844/ajassp.2009.1526.1530.
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Hoseinzadeh, Bakhtyar, Filipe Faria da Silva, and Claus Leth Bak. "Decentralized Coordination of Load Shedding and Plant Protection Considering High Share of RESs." IEEE Transactions on Power Systems 31, no. 5 (September 2016): 3607–15. http://dx.doi.org/10.1109/tpwrs.2015.2493101.
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Hongesombut, Komsan, Suphicha Punyakunlaset, and Sillawat Romphochai. "Under Frequency Protection Enhancement of an Islanded Active Distribution Network Using a Virtual Inertia-Controlled-Battery Energy Storage System." Sustainability 13, no. 2 (January 6, 2021): 484. http://dx.doi.org/10.3390/su13020484.
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When an islanding condition caused by an unintentional single-line to ground fault occurs in an active distribution network with distributed generation, the frequency stability and protection issues remain challenging. Therefore, this paper presents the under frequency protection enhancement of the active distribution network using a virtual inertia-controlled-battery energy storage system to improve the frequency stability under the islanding condition caused by unintentional faults. The virtual inertia control is designed based on the direct and quadrature axis-controlled battery energy storage system to generate the virtual inertia power, compensating the system’s inertia to enhance the stability margin. The proposed method is verified by the simulation results that reveal the frequency stability performance and the under-frequency load shedding enhancement of the study active distribution network in Thailand. The study is divided into two cases: the normal control parameters and the parameter uncertainty scenarios, compared with a power-frequency droop control. The simulation results demonstrate that the proposed virtual inertia control can effectively improve the frequency and transient stabilities in the islanding condition, diminishing the number of loads disconnected by the proposed under-frequency load shedding scheme.
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Dai, JJ. "Automatic Load-Shedding Protection at a Coal-Chemical Plant: Examining and Designing Effective Low-Frequency Backup Protection Methods." IEEE Industry Applications Magazine 26, no. 5 (September 2020): 77–88. http://dx.doi.org/10.1109/mias.2020.2982575.
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Seyedi. "Design of New Load Shedding Special Protection Schemes for a Double Area Power System." American Journal of Applied Sciences 6, no. 2 (February 1, 2009): 317–27. http://dx.doi.org/10.3844/ajassp.2009.317.327.
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Seyedi, H., and M. Sanaye-Pas. "Design of New Load Shedding Special Protection Schemes for a Double Area Power System." American Journal of Applied Sciences 6, no. 2 (February 1, 2009): 317–27. http://dx.doi.org/10.3844/ajas.2009.317.327.
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Sodin, Denis, Rajne Ilievska, Andrej Čampa, Miha Smolnikar, and Urban Rudez. "Proving a Concept of Flexible Under-Frequency Load Shedding with Hardware-in-the-Loop Testing." Energies 13, no. 14 (July 13, 2020): 3607. http://dx.doi.org/10.3390/en13143607.
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It is widely recognized that in the transition from conventional electrical power systems (EPSs) towards smart grids, electrical voltage frequency will be greatly affected. This is why this research is extremely valuable, especially since rate-of-change-of-frequency (RoCoF) is often considered as a potential means of resolving newly arisen problems, but is often challenged in practice due to the noise and its oscillating character. In this paper, the authors further developed and tested one of the new technologies related to under-frequency load shedding (UFLS) protection. Since the basic idea was to enhance the selected technology’s readiness level, a hardware-in-the-loop (HIL) setup with an RTDS was assembled. The under-frequency technology was implemented in an intelligent electronic device (IED) and included in the HIL setup. The IED acted as one of several protection devices, representing a last-resort system protection scheme. All main contributions of this research deal with using RoCoF in an innovative UFLS scheme under test: (i) appropriate selection and parameterization of RoCoF filtering techniques does not worsen under-frequency load shedding during fast-occurring events, (ii) locally measured RoCoF can be effectively used for bringing a high level of flexibility to a system-wide scheme, and (iii) diversity of relays and RoCoF-measuring techniques is an advantage, not a drawback.
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NUGRAHA, RIFKI FIKRANDANI, and TEGUH ARFIANTO. "Simulasi ETAP untuk Evaluasi Proteksi Gangguan Tegangan Lebih Generator Unit 3 PLTP Kamojang." MIND Journal 6, no. 1 (August 1, 2021): 57–72. http://dx.doi.org/10.26760/mindjournal.v6i1.57-72.
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AbstrakPada penelitian ini dilakukan evaluasi proteksi gangguan tegangan lebih pada generator Unit 3 PLTP Kamojang yang diproteksi oleh sebuah relay tegangan lebih menggunakan simulasi pada software ETAP. Simulasi dilakukan untuk melihat bagaimana cara kerja relay tegangan lebih dan bentuk tegangan lebih yang terjadi pada terminal generator. Skenario simulasi yang digunakan yaitu melakukan pelepasan beban 50,7 MW dan relay yang digunakan dalam simulasi berfungsi untuk menyalakan alarm saat terjadi tegangan lebih. Hasil simulasi memperlihatkan bahwa pada saat terjadi pelepasan beban, relay tegangan lebih menyalakan alarm 1,1 detik setelah membaca tegangan naik hingga 13 kV atau sebesar 110% dari tegangan nominalnya, kemudian tegangan terminal generator naik hingga 13,2 kV hingga kembali ke kondisi steady state 5 detik setelah terjadi kenaikkan tegangan. Hasil simulasi tersebut menunjukkan bahwa relay tegangan lebih yang terpasang pada terminal generator Unit 3 bekerja sesuai dengan fungsinya yaitu untuk memberikan alarm ketika tegangan lebih terjadi.Kata kunci: pelepasan beban, proteksi generator, relay proteksi, simulasi generator, tegangan lebihAbstractThis study evaluates overvoltage fault protection on the generator Unit 3 PLTP Kamojang which is protected by an overvoltage relay using simulation on ETAP software. Simulations are carried out to see how the overvoltage relay works and the form of overvoltage that occurs at the generator terminals. The scenario used is by do a load shedding of 53,3MW, the relay used in this simulation has a function to turn on the alarm when overvoltage occurs. The results show that when a load shedding occurs, the overvoltage relay turns on the alarm 1,1 seconds after reading the voltage up to 13 kV or 110% of the nominal voltage, then the generator terminal voltage rises to 13.2 kV until it returns to steady state 5 seconds after the voltage increase. The simulation results indicate that the overvoltage relay installed at the generator terminal Unit 3 works according to its function, namely to provide a warning when an overvoltage occurs.Keywords: generator protection, load shedding, overvoltage, protection relay, generator simulation
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Hong, Ying-Yi, and Chih-Yang Hsiao. "Event-Based Under-Frequency Load Shedding Scheme in a Standalone Power System." Energies 14, no. 18 (September 8, 2021): 5659. http://dx.doi.org/10.3390/en14185659.
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Under-frequency load shedding (UFLS) prevents a power grid from a blackout when a severe contingency occurs. UFLS schemes can be classified into two categories—event-based and response-driven. A response-driven scheme utilizes 81L relays with pre-determined settings while an event-based scheme develops a pre-specified look-up table. In this work, an event-based UFLS scheme is presented for use in an offshore standalone power grid with renewables to avoid cascading outages due to low frequency protection of wind power generators and photovoltaic arrays. Possible “N-1” and “N-2” forced outages for peak and off-peak load scenarios in summer and winter are investigated. For each forced outage event, the total shed load is minimized and the frequency nadir is maximized using particle swarm optimization (PSO). In order to reduce the computation time, initialization and parallel computing are implemented using MATLAB/Simulink because all forced outage events and all particles in PSO are mutually independent. A standalone 38-bus power grid with two wind turbines of 2 × 2 MW and photovoltaics of 7.563 MW was studied. For each event, the proposed method generally obtains a result with a smaller shed load and a smaller overshoot frequency than the utility and existing methods. These simulation results verify that the proposed method is practically applicable in a standalone power system with penetration of renewables.
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Pal, Diptak, Balimidi Mallikarjuna, Pathirikkat Gopakumar, M. Jaya Bharata Reddy, Bijaya Ketan Panigrahi, and Dusmanta Kumar Mohanta. "Probabilistic Study of Undervoltage Load Shedding Scheme to Mitigate the Impact of Protection System Hidden Failures." IEEE Systems Journal 14, no. 1 (March 2020): 862–69. http://dx.doi.org/10.1109/jsyst.2019.2901350.
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Han, Tian Zhen, Qi Yang, Yun Ting Song, Xiao Jun Tang, Qing Kui Guo, Yong Yu Yuan, and Jian Jun Sun. "The Influence of Motor Low Voltage Trip on under-Frequency Load Shedding in the Electric Network of Refinery Enterprise." Advanced Materials Research 732-733 (August 2013): 1119–24. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.1119.
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A simple frequency response model is generally used in UFLS (under-frequency load shedding) design, without considering the impact of voltage on the frequency. In fact, in the case of large active and reactive shortage power, the system will suffer from the low voltage problem by the emergence of low frequency, which easily leads a large number of motors tripping due to low voltage protection trip in the UFLS process. The influence on UFLS is compared and problems needed to solve are put forward.
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Bevrani, Hassan, Mehrdad Gholami, and Neda Hajimohammadi. "Microgrids Emergency Control and Protection." International Journal of Energy Optimization and Engineering 2, no. 1 (January 2013): 78–100. http://dx.doi.org/10.4018/ijeoe.2013010106.
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Economical harvesting of electrical energy on a large scale considering the environmental issues is a challenge. As a solution, Microgrids (MGs) promise to facilitate the widely penetration of renewable energy sources (RESs) and energy storage devices into the power systems, reduce system losses and greenhouse gas emissions, and increase the reliability of the electricity supply to the customers. Although the concept of MG is already established, the control strategies and energy management systems for MGs which cover power interchange, system stability, frequency and voltage regulation, active and reactive power control, islanding detection, grid synchronization, following contingencies and emergency conditions are still under development. Like a conventional power system, a Micro-grid (MG) needs emergency control and protection schemes to have secure and stable operation. Since MG can operate in both grid-connected and islanded mode, in addition to the control loops and protection schemes, extra issues must be considered. Transition between two operation modes requires an extra control plan to eliminate and stabilize transients due to mode changing. This paper presents an overview of the key issues and new challenges on emergency control and protection plans in the MG systems. The most important emergency control and protection schemes such as load shedding methods that have been presented over the past years are summarized.
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Xu, Xiaohong, Zhuang Ding, Qianliang Yuan, Jiaxin Ding, Jindou Li, Weiqi Wang, Yanlong Cong, et al. "A genotype VII Newcastle disease virus-like particles confer full protection with reduced virus load and decreased virus shedding." Vaccine 37, no. 3 (January 2019): 444–51. http://dx.doi.org/10.1016/j.vaccine.2018.11.068.
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Thalassinakis, E. J., E. N. Dialynas, and D. Agoris. "Method Combining ANNs and Monte Carlo Simulation for the Selection of the Load Shedding Protection Strategies in Autonomous Power Systems." IEEE Transactions on Power Systems 21, no. 4 (November 2006): 1574–82. http://dx.doi.org/10.1109/tpwrs.2006.879293.
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Grozdanovski, Jovancho, Rafael Mihalic, and Urban Rudez. "WAMS-Supported Power Mismatch Optimization for Secure Intentional Islanding." Energies 14, no. 10 (May 12, 2021): 2790. http://dx.doi.org/10.3390/en14102790.
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It is expected that a coordinated operation of several system integrity protection schemes will become a necessity in the future. This research represents an innovative strategy for coordinating under-frequency load shedding and intentional controlled islanding schemes for improving electric power system stability and resilience. In the great majority of real-world cases, both approaches follow conventional tactics, i.e., disconnecting a fixed number of feeders at predefined frequency thresholds and isolating a predefined area of a power system regardless of the actual conditions. Under the newly arisen network conditions in which weather-dependent distributed energy sources introduce a significant level of intermittency, conventional approaches need to be upgraded in order to retain a high level of power system operation security. In this paper, a mixed-integer linear programming approach is used to adjust the island size, including/excluding additional substations according to the available amount of generation in the region. The fine-tuning of the power rebalancing is achieved by potentially blocking selected load shedding stages. This minimizes the power imbalance of the newly formed islands, which helps to reduce the number of partial or even total blackouts and also accelerates the power system’s restoration process. The optimization approach was tested on a generic IEEE 39-bus network and shows promising results along with the capability of coping with real-world applications using wide-area monitoring systems as a source of real-time measurements. The results also indicated the importance of appropriate load modelling since both voltage and frequency dependence are recognized to have a significant effect on intentional controlled islanding.
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Berhanu, Aklile, David S. King, Stacie Mosier, Robert Jordan, Kevin F. Jones, Dennis E. Hruby, and Douglas W. Grosenbach. "ST-246 Inhibits In Vivo Poxvirus Dissemination, Virus Shedding, and Systemic Disease Manifestation." Antimicrobial Agents and Chemotherapy 53, no. 12 (September 14, 2009): 4999–5009. http://dx.doi.org/10.1128/aac.00678-09.
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ABSTRACT Orthopoxvirus infections, such as smallpox, can lead to severe systemic disease and result in considerable morbidity and mortality in immunologically naïve individuals. Treatment with ST-246, a small-molecule inhibitor of virus egress, has been shown to provide protection against severe disease and death induced by several members of the poxvirus family, including vaccinia, variola, and monkeypox viruses. Here, we show that ST-246 treatment not only results in the significant inhibition of vaccinia virus dissemination from the site of inoculation to distal organs, such as the spleen and liver, but also reduces the viral load in organs targeted by the dissemination. In mice intranasally infected with vaccinia virus, virus shedding from the nasal and lung mucosa was significantly lower (∼22- and 528-fold, respectively) upon ST-246 treatment. Consequently, virus dissemination from the nasal site of replication to the lung also was dramatically reduced, as evidenced by a 179-fold difference in virus levels in nasal versus bronchoalveolar lavage. Furthermore, in ACAM2000-immunized mice, vaccination site swabs showed that ST-246 treatment results in a major (∼3,900-fold by day 21) reduction in virus detected at the outside surfaces of lesions. Taken together, these data suggest that ST-246 would play a dual protective role if used during a smallpox bioterrorist attack. First, ST-246 would provide therapeutic benefit by reducing the disease burden and lethality in infected individuals. Second, by reducing virus shedding from those prophylactically immunized with a smallpox vaccine or harboring variola virus infection, ST-246 could reduce the risk of virus transmission to susceptible contacts.
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Dobrijevic, Djordje, and Dragan Popovic. "An unified external network equivalent in steady-state security assessment." Facta universitatis - series: Electronics and Energetics 23, no. 2 (2010): 179–89. http://dx.doi.org/10.2298/fuee1002179d.
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The basic objective of this paper is to present the relevant methodological and practical aspects of forming the unified external network equivalent. This equivalent consistently respects the effects of primary voltage and frequency control of external power system, including the real possibilities and limitations, as well as the effects of possible action of under frequency load shedding or under frequency protection of generator. The first practical experience in the application of the equivalent has been gained on an example of the synchronous parallel operation of the 2nd UCTE Synchronous Zone. The results obtained show a very good accuracy of unified external network equivalent formed and also show the very high speed of steady-state security assessment in context of real interconnection.
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Kiss, István, Krisztina Szigeti, Zalán G. Homonnay, Vivien Tamás, Han Smits, and Roman Krejci. "Maternally Derived Antibody Levels Influence on Vaccine Protection against PCV2d Challenge." Animals 11, no. 8 (July 29, 2021): 2231. http://dx.doi.org/10.3390/ani11082231.
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Piglets from a porcine circovirus type 2 (PCV2) stable farm of low and high levels of maternally derived antibodies (MDA) against PCV2 were vaccinated either with a whole virus type or a PCV2 ORF2 antigen-based commercial subunit vaccine at three weeks of age. Two non-vaccinated groups served as low and high MDA positive controls. At four weeks post vaccination, all piglets were challenged with a PCV2d-2 type virus strain and were checked for parameters related to vaccine protection over a four-week observation period. MDA levels evidently impacted the outcome of the PCV2d-2 challenge in non-vaccinated animals, while it did not have a significant effect on vaccine-induced protection levels. The humoral immune response developed faster in the whole virus vaccinates than in the subunit vaccinated pigs in the low MDA groups. Further, high MDA levels elicited a stronger negative effect on the vaccine-induced humoral immune response for the subunit vaccine than for the whole virus vaccine. The group-based oral fluid samples and the group mean viraemia and faecal shedding data correlated well, enabling this simple, and animal welfare-friendly sampling method for the evaluation of the PCV2 viral load status of these nursery piglets.
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Xu, Yong Sheng. "The Study on Isolated Power Control System Based on Coordinated Control." Applied Mechanics and Materials 192 (July 2012): 328–32. http://dx.doi.org/10.4028/www.scientific.net/amm.192.328.
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This paper analysis the formation conditions of isolated power system, its influencing factors, revealing the operation mode, automatic safety device, generator protection regulation characteristics and these factors to stable operation of isolated power system. The dynamic models for isolated power system with generating unit of medium and small capacity are proposed in the paper to meet the need of the applicable ones to study their dynamic characteristics. The differences between isolated and the interconnected power system in the frequency characteristics are proposed and consider into low-frequency load shedding scheme and optimization methods that can meet both isolated and the interconnected power system frequency stability requirements. Not only more proper control strategy of units but their evaluation indexes are suggested to improve performance and achieve stability in islanded power system.
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Alhelou, Hassan, Mohamad Hamedani-Golshan, Takawira Njenda, and Pierluigi Siano. "Wide-Area Measurement System-Based Optimal Multi-Stage Under-Frequency Load-Shedding in Interconnected Smart Power Systems Using Evolutionary Computing Techniques." Applied Sciences 9, no. 3 (February 1, 2019): 508. http://dx.doi.org/10.3390/app9030508.
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Power systems that are known as the most complex systems encounter different types of disturbances and emergence events. To operate such systems in a stable mode, several control protection techniques are in need. Frequency plays a vital role in power systems and needs to be properly maintained in a permissible level. To this end, under-frequency load-shedding (UFLS) techniques are used to intercept the frequency decline when a system encounters a severe disturbance. In this paper, a novel, wide-area measurement system (WAMS)-based optimal UFLS technique is proposed. The system frequency response (SFR) model is identified online based on the real-time measurements collected by phasor measurement units (PMUs). Then, the SFR model is used to design a new optimal multi-stage UFLS scheme. Imperialist competitive algorithm (ICA), which is a powerful evolutionary computing method, is then adopted for solving the suggested multi-stage UFLS optimization problem. The applicability of the proposed method is shown on a practical test system. The effectiveness of the proposed optimal multi-stage UFLS scheme is verified by several simulation and comparison scenarios.
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Wu, Yuan-Kang, Kuo-Ting Tang, Zheng Kuan Lin, and Wen-Shan Tan. "Flexible Power System Defense Strategies in an Isolated Microgrid System with High Renewable Power Generation." Applied Sciences 10, no. 9 (May 2, 2020): 3184. http://dx.doi.org/10.3390/app10093184.
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This work develops an underfrequency preventive control strategy for an islanded power system with a high penetration of wind power generation. First, the preventive control strategy uses the frequency nadir forecasting module to analyze the frequency stability under largest diesel generator tripping (N-1) contingency events. If predicted frequency nadir is too low, four frequency support methods are then analyzed and used for preventing potential frequency stability problem. They include generator rescheduling (GR), the use of battery energy storage system (BESS), direct load control (DLC) and emergency demand response program (EDRP). In terms of the GR method, the optimal diesel generator dispatch is obtained, with sufficient frequency stability and minimal fuel cost and start-up cost. In the BESS method, the optimal instantaneous power output from BESS is obtained based on its frequency support capability. With the DLC or EDRP method, the optimal contract-based load-shedding or the load-reduction to provide frequency support is obtained, respectively. Then, the operating costs of each method to support frequency are analyzed. The research methods and simulation results are very useful to the low-frequency protection of actual power systems with high renewable power generation. This work proposed a complete defense strategy in a microgrid system. It combines GR, BESS, DLC and EDRP. Therefore, the system operators have many options to implement their defense strategies, based on the operating costs of various methods. In other words, the proposed defense strategy provides a more flexible solution for the protection of micro grids with a high renewable power penetration. Therefore, the solution considers the system safety and economical aspects.
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Lukosaityte, Deimante, Jean-Remy Sadeyen, Angita Shrestha, Joshua E. Sealy, Sushant Bhat, Pengxiang Chang, Paul Digard, and Munir Iqbal. "Engineered Recombinant Single Chain Variable Fragment of Monoclonal Antibody Provides Protection to Chickens Infected with H9N2 Avian Influenza." Vaccines 8, no. 1 (March 3, 2020): 118. http://dx.doi.org/10.3390/vaccines8010118.
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Passive immunisation with neutralising antibodies can be a potent therapeutic strategy if used pre- or post-exposure to a variety of pathogens. Herein, we investigated whether recombinant monoclonal antibodies (mAbs) could be used to protect chickens against avian influenza. Avian influenza viruses impose a significant economic burden on the poultry industry and pose a zoonotic infection risk for public health worldwide. Traditional control measures including vaccination do not provide rapid protection from disease, highlighting the need for alternative disease mitigation measures. In this study, previously generated neutralizing anti-H9N2 virus monoclonal antibodies were converted to single-chain variable fragment antibodies (scFvs). These recombinant scFv antibodies were produced in insect cell cultures and the preparations retained neutralization capacity against an H9N2 virus in vitro. To evaluate recombinant scFv antibody efficacy in vivo, chickens were passively immunized with scFvs one day before, and for seven days after virus challenge. Groups receiving scFv treatment showed partial virus load reductions measured by plaque assays and decreased disease manifestation. These results indicate that antibody therapy could reduce clinical disease and shedding of avian influenza virus in infected chicken flocks.
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Bernelin-Cottet, Cindy, Céline Urien, Maxence Fretaud, Christelle Langevin, Ivan Trus, Luc Jouneau, Fany Blanc, et al. "A DNA Prime Immuno-Potentiates a Modified Live Vaccine against the Porcine Reproductive and Respiratory Syndrome Virus but Does Not Improve Heterologous Protection." Viruses 11, no. 6 (June 25, 2019): 576. http://dx.doi.org/10.3390/v11060576.
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The porcine reproductive and respiratory syndrome virus (PRRSV), an RNA virus inducing abortion in sows and respiratory disease in young pigs, is a leading infectious cause of economic losses in the swine industry. Modified live vaccines (MLVs) help in controlling the disease, but their efficacy is often compromised by the high genetic diversity of circulating viruses, leading to vaccine escape variants in the field. In this study, we hypothesized that a DNA prime with naked plasmids encoding PRRSV antigens containing conserved T-cell epitopes may improve the protection of MLV against a heterologous challenge. Plasmids were delivered with surface electroporation or needle-free jet injection and European strain-derived PRRSV antigens were targeted or not to the dendritic cell receptor XCR1. Compared to MLV-alone, the DNA-MLV prime- boost regimen slightly improved the IFNγ T-cell response, and substantially increased the antibody response against envelope motives and the nucleoprotein N. The XCR1-targeting of N significantly improved the anti-N specific antibody response. Despite this immuno-potentiation, the DNA-MLV regimen did not further decrease the serum viral load or the nasal viral shedding of the challenge strain over MLV-alone. Finally, the heterologous protection, achieved in absence of detectable effective neutralizing antibodies, was not correlated to the measured antibody or to the IFNγ T-cell response. Therefore, immune correlates of protection remain to be identified and represent an important gap of knowledge in PRRSV vaccinology. This study importantly shows that a naked DNA prime immuno-potentiates an MLV, more on the B than on the IFNγ T-cell response side, and has to be further improved to reach cross-protection.
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Bangar Raju, L., and K. Subba Rao. "Integration of DERs for Optimal Sharing of Power in Grid Connected Mode as Well as Islanded Mode." International Journal of Engineering & Technology 7, no. 3.12 (July 20, 2018): 1118. http://dx.doi.org/10.14419/ijet.v7i3.12.17772.
Full textAbstract:
The Microgrid consists of distributed energy resources, DERs(distributed generators - DGs) and distributed storages - DSs), loads, PCC, energy management controllers etc., which are required for effective, efficient, reliable and seamless operation of microgrid in both grid connected mode and islanded mode. The heart of the microgrid is the integration part of the DERs with energy management controllers. Out of the methods available, hierarchical method of integrating DERs is selected in this paper. The method is based on the principle of hybrid particle swarm optimization (PSO) which takes into account of genetic algorithm (GA) and PSO. In this paper, the best part of particle to particle information sharing in GA is combined with fast convergence option in PSO, to get the optimum solution with minimum no of iterations. Integration of DERs is nothing but energy management in supply side management (SSM) as well as demand side management (DSM). DSM consists of load shedding or load shifting to an alternate feeder. The primary energy controller MC (microsource controller) controls voltage and frequency through droop control inverters. The secondary controller (MGCC) monitors the flow of active and reactive power in the microgrid and communicates to the DMS (distribution management system). The tertiary controller, DMS takes care of overall control of the network like export, import, islanding, economical aspects of the DERs operation in the microgrid. The energy management module (MGCC) must also contain protection co-ordination module (PCM) along with energy management module (EMM), for relay co-ordination as microgrid consists of two operating modes viz., grid connected mode and islanded mode. The fault currents substantially reduces to smaller values in islanded mode as DERs inertias are low. For this reason the PCM must have two settings and auto changeover of settings are required from one mode to another by PCM module to suit islanding and grid modes.
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Kao, Chi-Fei, Hue-Ying Chiou, Yen-Chen Chang, Cheng-Shun Hsueh, Chian-Ren Jeng, Pei-Shiue Tsai, Ivan-Chen Cheng, Victor Pang, and Hui-Wen Chang. "The Characterization of Immunoprotection Induced by a cDNA Clone Derived from the Attenuated Taiwan Porcine Epidemic Diarrhea Virus Pintung 52 Strain." Viruses 10, no. 10 (October 4, 2018): 543. http://dx.doi.org/10.3390/v10100543.
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The porcine epidemic diarrhea virus (PEDV) poses a great threat to the global swine industries and the unreliable protection induced by the currently available vaccines remains a major challenge. We previously generated a genogroup 2b (G2b) PEDV Taiwan Pintung 52 (PEDVPT) strain, PEDVPT-P96, and determined its promising host immune response against the virulent PEDVPT-P5 strain. To study the attenuation determinants of PEDVPT-P96 and establish a PEDVPT-P96-based recombinant vector as a vaccine platform for further antigenicity modification, iPEDVPT-P96, a full-length cDNA clone of PEDVPT-P96, was established. Comparing to the parental PEDVPT-P96 virus, the iPEDVPT-P96 virus showed efficient replication kinetics with a delayed decline of viral load and similar but much more uniform plaque sizes in Vero cells. In the 5-week-old piglet model, fecal viral shedding was observed in the PEDVPT-P96-inoculated piglets, whereas those inoculated with iPEDVPT-P96 showed neither detectable fecal viral shedding nor PEDV-associated clinical signs. Moreover, inoculation with iPEDVPT-P96 elicited comparable levels of anti-PEDV specific plasma IgG and fecal/salivary IgA, neutralizing antibody titers, and similar but less effective immunoprotection against the virulent PEDVPT-P5 challenge compared to the parental PEDVPT-P96. In the present study, an infectious cDNA clone of an attenuated G2b PEDV strain was successfully generated for the first time, and the in vitro and in vivo data indicate that iPEDVPT-P96 is further attenuated but remains immunogenic compared to its parental PEDVPT-P96 viral stock. The successful development of the iPEDVPT-P96 cDNA clone could allow for the manipulation of the viral genome to study viral pathogenesis and facilitate the rapid development of effective vaccines.
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Loconsole, Daniela, Emma Diletta Stea, Anna Sallustio, Giulia Fontò, Virginia Pronzo, Simona Simone, Francesca Centrone, Marisa Accogli, Loreto Gesualdo, and Maria Chironna. "Severe COVID-19 by SARS-CoV-2 Lineage B.1.1.7 in Vaccinated Solid-Organ Transplant Recipients: New Preventive Strategies Needed to Protect Immunocompromised Patients." Vaccines 9, no. 8 (July 21, 2021): 806. http://dx.doi.org/10.3390/vaccines9080806.
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Background: Solid-organ transplant (SOT) recipients are at a high risk of severe COVID-19, and are priority for vaccination. Here, we describe three cases of severe COVID-19 caused by SARS-CoV-2 B.1.1.7 lineage in vaccinated SOT recipients. Methods: Three SOT patients were hospitalized in the Policlinico Hospital of Bari (southern Italy) and underwent nasopharyngeal swabs for molecular detection of SARS-CoV-2 genes and spike protein mutations by real-time PCR. One sample was subjected to whole-genome sequencing. Results: One patient was a heart transplant recipient and two were kidney transplant recipients. All were hospitalized with severe COVID-19 between March and May 2021. Two patients were fully vaccinated and one had received only one dose of the BNT162b2 mRNA vaccine. All the patients showed a high viral load at diagnosis, and molecular typing revealed the presence of B.1.1.7 lineage SARS-CoV-2. In all three cases, prolonged viral shedding was reported. Conclusions: The three cases pose concern about the role of the B.1.1.7 lineage in severe COVID-19 and about the efficacy of COVID-19 vaccination in immunocompromised patients. Protecting immunocompromised patients from COVID-19 is a challenge. SOT recipients show a suboptimal response to standard vaccination, and thus, an additive booster or a combined vaccination strategy with mRNA, protein/subunit, and vector-based vaccines may be necessary. This population should continue to practice strict COVID-19 precautions post-vaccination, until new strategies for protection are available.
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Ramagoma, Justice, and Chris Adendorff. "Managing a transition to green energy sources: The perspectives of energy practitioners in the Southern African Development Community region." Journal of Energy in Southern Africa 27, no. 4 (December 21, 2016): 77. http://dx.doi.org/10.17159/2413-3051/2016/v27i4a1638.
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The Southern African Development Community (SADC) region has low energy security, exacerbated by electricity power cuts and load-shedding in almost all its member states. Green energy has the potential to contribute to the shortfall in the supply of energy required on the grid network during daily (morning and evening) and seasonal (winter) peak periods. The Statistica 12 program was used to analyse and compare responses between identified groups in the SADC region’s Energy sector. Multivariate analysis of variance and analysis of variance were used to examine associations between variables within the identified categories of respondents, and conclusions were made about six hypotheses. The categories of respondents sampled included: people associated with fossil fuel and renewable energy; people with experience of 1-6 years and more than 6 years; researchers and industry practitioners; practitioners based in South Africa and in other SADC countries; and a category based on practitioners’ positions (junior managers, middle managers, and senior managers) in their respective organisations. The study found that energy practitioners generally support a transition to green energy sources and there is consensus that the uptake of green energy will be slow initially, driven by low costs of fossil-based sources, but the uptake will eventually grow exponentially to a point of driving industries in future. The study recommends that SADC countries prioritise mapping of green energy resources to facilitate the selection of suitable green energy options in order to meet local energy needs and environmental protection. Research and development of suitable green energy storage technologies to overcome intermittency of some green energy sources must be expedited in the region.
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Ke, Yi Kuan, and Pei Hwa Huang. "Study of Load Shedding by IEC61850 Implementation." Applied Mechanics and Materials 336-338 (July 2013): 1814–17. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.1814.
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The main purpose of this paper is to study the implementation of load shedding under the condition of IEC61850 (Communication Networks and Systems in Substations) communication exchange in the power system. The strategy of load shedding with IEC61850 GOOSE (Generic Object Oriented Substation Event) message relies on fast transmission of the signal to shed unstable regions for maintaining system safety. The current strategy for load shedding in the substation is to use hardwire and dispatch solutions to implement related applications of load shedding. For integrating protective relays in substations, IEC61850 GOOSE schemes can customize both a ring and a star construct based on TCP/IP Ethernet to have flexible dispatch of smart grid solutions. The functions of relay integrated with the GOOSE message play important roles to implement peer to peer communication to accomplish the load shedding strategy.
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Basha, A. M. "Self-Diagnostic Digital Underfrequency Relay Coupled with a 3–Zone Distance Algorithm." International Journal of Electrical Engineering & Education 30, no. 2 (April 1993): 161–69. http://dx.doi.org/10.1177/002072099303000212.
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Self-diagnostic digital underfrequency relay coupled with a 3–zone distance algorithm The paper reports a digital underfrequency relay for shedding and restoration of loads in an electric power system coupled with a 3-zone distance algorithm for the protection of feeder lines. The relay incorporates self-diagnosing techniques for detecting failures. The prototype developed has been satisfactorily tested for its performance.
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Hann, Richard, Adriana Enache, Mikkel Cornelius Nielsen, Bård Nagy Stovner, Jeroen van Beeck, Tor Arne Johansen, and Kasper Trolle Borup. "Experimental Heat Loads for Electrothermal Anti-Icing and De-Icing on UAVs." Aerospace 8, no. 3 (March 18, 2021): 83. http://dx.doi.org/10.3390/aerospace8030083.
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Atmospheric in-flight icing on unmanned aerial vehicles (UAVs) is a significant hazard. UAVs that are not equipped with ice protection systems are usually limited to operations within visual line of sight or to weather conditions without icing risk. As many military and commercial UAV missions require flights beyond visual line of sight and into adverse weather conditions, energy-efficient ice protection systems are required. In this experimental study, two electro-thermal ice protection systems for fixed-wing UAVs were tested. One system was operated in anti-icing and de-icing mode, and the other system was designed as a parting strip de-icing system. Experiments were conducted in an icing wind tunnel facility for varying icing conditions at low Reynolds numbers. A parametric study over the ice shedding time was used to identify the most energy-efficient operation mode. The results showed that longer intercycle durations led to higher efficiencies and that de-icing with a parting strip was superior compared to anti-icing and de-icing without a parting strip. These findings are relevant for the development of energy-efficient systems in the future.
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Griffin, Amanda J., Lin-Xi Li, Sabrina Voedisch, Oliver Pabst, and Stephen J. McSorley. "Dissemination of Persistent Intestinal Bacteria via the Mesenteric Lymph Nodes Causes Typhoid Relapse." Infection and Immunity 79, no. 4 (January 24, 2011): 1479–88. http://dx.doi.org/10.1128/iai.01033-10.
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ABSTRACTEnteric pathogens can cause relapsing infections in a proportion of treated patients, but greater understanding of this phenomenon is hindered by the lack of appropriate animal models. We report here a robust animal model of relapsing primary typhoid that initiates after apparently successful antibiotic treatment of susceptible mice. Four days of enrofloxacin treatment were sufficient to reduce bacterial loads below detectable levels in all major organs, and mice appeared otherwise healthy. However, any interruption of further antibiotic therapy allowed renewed fecal shedding and renewed bacterial growth in systemic tissues to occur, and mice eventually succumbed to relapsing infection.In vivoimaging of luminescentSalmonellaidentified the mesenteric lymph nodes (MLNs) as a major reservoir of relapsing infection. A magnetic-bead enrichment strategy isolated MLN-resident CD11b+Gr-1−monocytes associated with low numbers of persistentSalmonella. However, the removal of MLNs increased the severity of typhoid relapse, demonstrating that this organ serves as a protective filter to restrain the dissemination of bacteria during antibiotic therapy. Together, these data describe a robust animal model of typhoid relapse and identify an important intestinal phagocyte subset involved in protection against the systemic spread of enteric infection.
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van Doremalen, Neeltje, Jyothi N. Purushotham, Jonathan E. Schulz, Myndi G. Holbrook, Trenton Bushmaker, Aaron Carmody, Julia R. Port, et al. "Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces viral shedding after SARS-CoV-2 D614G challenge in preclinical models." Science Translational Medicine 13, no. 607 (July 27, 2021): eabh0755. http://dx.doi.org/10.1126/scitranslmed.abh0755.
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ChAdOx1 nCoV-19/AZD1222 is an approved adenovirus-based vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) currently being deployed globally. Previous studies in rhesus macaques revealed that intramuscular vaccination with ChAdOx1 nCoV-19/AZD1222 provided protection against pneumonia but did not reduce shedding of SARS-CoV-2 from the upper respiratory tract. Here, we investigated whether intranasally administered ChAdOx1 nCoV-19 reduces detection of virus in nasal swabs after challenging vaccinated macaques and hamsters with SARS-CoV-2 carrying a D614G mutation in the spike protein. Viral loads in swabs obtained from intranasally vaccinated hamsters were decreased compared to control hamsters, and no viral RNA or infectious virus was found in lung tissue after a direct challenge or after direct contact with infected hamsters. Intranasal vaccination of rhesus macaques resulted in reduced virus concentrations in nasal swabs and a reduction in viral loads in bronchoalveolar lavage and lower respiratory tract tissue. Intranasal vaccination with ChAdOx1 nCoV-19/AZD1222 reduced virus concentrations in nasal swabs in two different SARS-CoV-2 animal models, warranting further investigation as a potential vaccination route for COVID-19 vaccines.
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Spiri, Andrea M., Barbara Riond, Martina Stirn, Marilisa Novacco, Marina L. Meli, Felicitas S. Boretti, Imogen Herbert, Margaret J. Hosie, and Regina Hofmann-Lehmann. "Modified-Live Feline Calicivirus Vaccination Reduces Viral RNA Loads, Duration of RNAemia, and the Severity of Clinical Signs after Heterologous Feline Calicivirus Challenge." Viruses 13, no. 8 (July 30, 2021): 1505. http://dx.doi.org/10.3390/v13081505.
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Feline calicivirus (FCV) is a common cat virus causing clinical signs such as oral ulcerations, fever, reduced general condition, pneumonia, limping and occasionally virulent-systemic disease. Efficacious FCV vaccines protect against severe disease but not against infection. FCV is a highly mutagenic RNA virus whose high genetic diversity poses a challenge in vaccine design. The use of only one modified-live FCV strain over several decades might have driven the viral evolution towards more vaccine-resistant variants. The present study investigated the clinical signs, duration, and amount of FCV shedding, RNAemia, haematological changes and acute phase protein reaction in SPF cats after subcutaneous modified-live single strain FCV vaccination or placebo injection and two subsequent oronasal heterologous FCV challenge infections with two different field strains. Neither clinical signs nor FCV shedding from the oropharynx and FCV RNAemia were detected after vaccination. After the first experimental infection, vaccinated cats had significantly lower clinical scores, less increased body temperature and lower acute phase protein levels than control cats. The viral RNA loads from the oropharynx and duration and amount of RNAemia were significantly lower in the vaccinated animals. No clinical signs were observed in any of the cats after the second experimental infection. In conclusion, FCV vaccination was beneficial for protecting cats from severe clinical signs, reducing viral loads and inflammation after FCV challenge.
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Christopher-Hennings, Jane, Eric A. Nelson, Gary C. Althouse, and Joan Lunney. "Comparative antiviral and proviral factors in semen and vaccines for preventing viral dissemination from the male reproductive tract and semen." Animal Health Research Reviews 9, no. 1 (March 19, 2008): 59–69. http://dx.doi.org/10.1017/s1466252307001387.
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AbstractMany animal and human viruses are disseminated via semen, but there is little information on how to measure and stimulate protective antiviral immunity in the male reproductive tract and semen. This information is important since successful vaccination through the stimulation of protective immune responses could be a mechanism to prevent viral contamination of semen and subsequent wide spread viral dissemination. Even control of the infection by shortening the duration of viral shedding and lowering the viral load in semen would lessen the chances of viral dissemination through this route. This review will highlight the current knowledge of immunity in the male reproductive tract and summarize ‘antiviral’ as well as ‘proviral’ factors in semen such as cytokines, cells, antibodies, antimicrobial peptides, enzymes, hormones and growth factors. These factors must provide a fine balance between ‘immunosuppression’ in semen needed to protect sperm viability and ‘immunocompetency’ to prevent pathogen contamination. The review will also suggest continuing challenges to researchers for preventing viral dissemination via semen and propose a large animal model for continued research in this important area.
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Fernández-González, Marta, José A. García, Sergio Padilla, Javier García-Abellán, Vanesa Agulló, Félix Gutiérrez, and Mar Masiá. "Rectal and seminal HIV-1 RNA decay towards virological suppression in infected MSM initiating dolutegravir/abacavir/lamivudine." Journal of Antimicrobial Chemotherapy 75, no. 3 (November 26, 2019): 668–74. http://dx.doi.org/10.1093/jac/dkz482.
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Abstract Background The time at which the protective effect of starting ART is achieved in male rectal and genital reservoirs is not clearly established. Objectives To quantify HIV-1 RNA decay towards virological suppression in rectal mucosa and semen in MSM starting dolutegravir/abacavir/lamivudine (DTG/ABC/3TC). Methods A longitudinal cohort study of ART-naive HIV-positive MSM was performed. HIV-1 RNA was quantified in rectal mucosa and seminal plasma samples at day 1 of ART initiation (baseline) and every 4 weeks until week 20 (w20; all participants) and week 64 (w64; 6 of 12 participants). Results Twelve MSM, with median (IQR) age 36 (33–40) years and baseline CD4+ count 449 (411–503) cells/mm3, were included. At baseline, HIV-1 RNA was detectable in all plasma and seminal samples and 10/12 rectal samples. All participants achieved plasma virological suppression by w20, whereas HIV-1 RNA was detectable in 42% and 50% of seminal and rectal samples, respectively. At w64, HIV-1 RNA was detectable in 1/6 seminal and 1/6 rectal samples. A relationship of baseline seminal and rectal HIV-1 RNA levels with viral shedding in reservoirs (HIV-1 RNA >200 copies/mL or copies/swab) was found. In addition, a significant association of baseline plasma viral load with time to rectal HIV-1 RNA <200 copies/swab was found (P=0.025). Conclusions Viral decay after initiating DTG/ABC/3TC is slower in rectal mucosa and semen than in plasma. Approximately half of patients achieved undetectable HIV-1 RNA levels in rectal and genital secretions at w20 and in some patients viral shedding persisted for up to 1 year. Initial plasma viral load influences time to rectal suppression.
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Querido, Sara, Carolina Ormonde, Teresa Adragão, Inês Costa, Maria Ana Pessanha, Perpétua Gomes, and André Weigert. "Outcomes of Living Kidney Donor Candidates and Living Kidney Recipient Candidates with JC Polyomavirus and BK Polyomavirus Viruria." International Journal of Nephrology 2021 (August 19, 2021): 1–7. http://dx.doi.org/10.1155/2021/8010144.
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Introduction. Recent data have emerged about a protective association between JCV viruria and chronic kidney disease (CKD). Material and Methods. Single-center retrospective cohort study; 230 living kidney donors (LKD) candidates and 59 potential living kidney receptors (LKR) were enrolled. Plasma and urinary JCV and BKV viral loads were measured in all LKD candidates and in nonanuric LKR candidates. Twenty-six living kidney transplant surgeries were performed. LKR were followed in order to evaluate BKV and JCV viremia and urinary viral shedding after KT. Results. In LKD candidates, JCV viruria was negatively associated with proteinuria of >200 mg/24 hours (JC viruric LKD: 12.5% vs JCV nonviruric LKD: 26.7%, p = 0.021 , OR:0.393; 95% CI: 0.181–0.854). In a multivariate analysis, LKD candidates with JCV viruria had a lower risk of proteinuria of >200 mg/24 hours ( p = 0.009 , OR: 0.342, 95% CI: 0.153–0.764), in a model adjusted for age, gender, presence of hypertension, and eGFR <80 mL/min. Prevalence of JCV viruria was higher in LKD candidates when compared with LKR candidates (40.0% vs 1.7%, p < 0.001 ). Among the 26 LKR, 14 (53.8%) KT patients evolved with JCV viruria; 71.4% received a graft from a JCV viruric donor. Conclusion. Our data corroborate the recent findings of an eventual protective association between JCV viruria and kidney disease, and we extrapolated this concept to a South European population.
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López-Serrano, Sergi, Lorena Cordoba, Mónica Pérez-Maillo, Patricia Pleguezuelos, Edmond J. Remarque, Thomas Ebensen, Carlos A. Guzmán, Dennis Christensen, Joaquim Segalés, and Ayub Darji. "Immune Responses to Pandemic H1N1 Influenza Virus Infection in Pigs Vaccinated with a Conserved Hemagglutinin HA1 Peptide Adjuvanted with CAF®01 or CDA/αGalCerMPEG." Vaccines 9, no. 7 (July 6, 2021): 751. http://dx.doi.org/10.3390/vaccines9070751.
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This study aimed to evaluate the immune response and protection correlates against influenza virus (IV) infection in pigs vaccinated with the novel NG34 HA1 vaccine candidate adjuvanted with either CAF®01 or CDA/αGalCerMPEG (αGCM). Two groups of six pigs each were vaccinated intramuscularly twice with either NG34 + CAF®01 or NG34 + CDA/αGCM. As controls, groups of animals (n = 6 or 4) either non-vaccinated or vaccinated with human seasonal trivalent influenza vaccine or NG34 + Freund’s adjuvant were included in the study. All animal groups were challenged with the 2009 pandemic (pdm09) strain of H1N1 (total amount of 7 × 106 TCID50/mL) via intranasal and endotracheal routes 21 days after second vaccination. Reduced consolidated lung lesions were observed both on days three and seven post-challenge in the animals vaccinated with NG34 + CAF®01, whereas higher variability with relatively more severe lesions in pigs of the NG34 + CDA/αGCM group on day three post-infection. Among groups, animals vaccinated with NG34 + CDA/αGCM showed higher viral loads in the lung at seven days post infection whereas animals from NG34 + CAF®01 completely abolished virus from the lower respiratory tract. Similarly, higher IFNγ secretion and stronger IgG responses against the NG34 peptide in sera was observed in animals from the NG34 + CAF®01 group as compared to the NG34 + CDA/αGCM. NG34-vaccinated pigs with adjuvanted CAF®01 or CDA/αGCM combinations resulted in different immune responses as well as outcomes in pathology and viral shedding.
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Wang, Kening, Kyle N. Goodman, Daniel Y. Li, Mark Raffeld, Mayra Chavez, and Jeffrey I. Cohen. "A Herpes Simplex Virus 2 (HSV-2) gD Mutant Impaired for Neural Tropism Is Superior to an HSV-2 gD Subunit Vaccine To Protect Animals from Challenge with HSV-2." Journal of Virology 90, no. 1 (November 11, 2015): 562–74. http://dx.doi.org/10.1128/jvi.01845-15.
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ABSTRACTA recent phase 3 trial with soluble herpes simplex virus 2 (HSV-2) glycoprotein D (gD2t) in adjuvant failed to show protection against genital herpes. We postulated that live attenuated HSV-2 would provide more HSV antigens for induction of virus-specific antibodies and cellular immunity than would gD2t. We previously reported an HSV-2 mutant, HSV2-gD27, in which the nectin-1 binding domain of gD2 is altered so that the virus is impaired for infecting neural cells, but not epithelial cells,in vitroand is impaired for infecting dorsal root ganglia in mice (K. Wang, J. D. Kappel, C. Canders, W. F. Davila, D. Sayre, M. Chavez, L. Pesnicak, and J. I. Cohen, J Virol 86:12891–12902, 2012, doi:10.1128/JVI.01055-12). Here we report that the mutations in HSV2-gD27 were stable when the virus was passaged in cell culture and during acute infection of mice. HSV2-gD27 was attenuated in mice when it was inoculated onto the cornea, intramuscularly (i.m.), intravaginally, and intracranially. Vaccination of mice i.m. with HSV2-gD27 provided better inhibition of challenge virus replication in the vagina than when the virus was used to vaccinate mice intranasally or subcutaneously. Comparison of i.m. vaccinations with HSV2-gD27 versus gD2t in adjuvant showed that HSV2-gD27 induced larger reductions of challenge virus replication in the vagina and reduced latent viral loads in dorsal root ganglia but induced lower serum neutralizing antibody titers than those obtained with gD2t in adjuvant. Taken together, our data indicate that a live attenuated HSV-2 vaccine impaired for infection of neurons provides better protection from vaginal challenge with HSV-2 than that obtained with a subunit vaccine, despite inducing lower titers of HSV-2 neutralizing antibodies in the serum.IMPORTANCEGenital herpes simplex is one of the most prevalent sexually transmitted diseases. Though HSV-2 disease is usually mild, it can be life threatening in neonates and immunocompromised persons. In addition, genital herpes increases the frequency of HIV infection and transmission. HSV-2 maintains a latent infection in sensory neurons and cannot be cleared with antiviral drugs. The virus frequently reactivates, resulting in virus shedding in the genital area, which serves as a source for transmission. A prophylactic vaccine is needed to prevent disease and to control the spread of the virus. Previous human trials of subunit vaccines have been unsuccessful. Here we report the results of vaccinating mice with a new type of live attenuated HSV-2 vaccine that is impaired for infection of neurons and provides better protection of mice than that obtained with a subunit vaccine. The strategy of altering the cell tropism of a virus is a new approach for a live attenuated vaccine.
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Flor, Jaime. "Surviving COVID-19 Pneumonia At Home: COVID Case #1906." Philippine Journal of Otolaryngology Head and Neck Surgery 35, no. 1 (May 16, 2020): 78–79. http://dx.doi.org/10.32412/pjohns.v35i1.1259.
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Dear Editor,
I was exposed to a COVID-19 positive cardiologist last March 1. I had ENT clinics until March 11, treating mostly patients with complaints of cough and fever (sinusitis and bronchitis). I felt that my facial mask, hooded magnifier lens, and gloves gave me enough protection. I was wrong. They were not sufficient. I had a temperature of 38°C on March 13 and went home immediately to self-isolate.
By March 15, I was coughing unremittingly and persistently as if a feather was stuck in my throat. I had no phlegm. I had no running nose, nor respiratory difficulty. But my rib muscles ached continuously - an intense, miserable pain not relieved by any position. I felt a severe point tenderness over both lower back ribs that even soft pillows could not diminish. I lacked sleep. I felt weaker as days went by. My taste was flat as I swallowed soups and arroz caldo but I still had my sense of smell.
On March 16, I took Clarithromycin 500 mg and N-Acetylcysteine 600 mg, both twice daily to treat what I diagnosed as acute pharyngitis. Two more days of severe coughing, fever and sore throat made me worry about COVID-19. How come I was not getting better? In fact, I was getting BITTER over this uncertainty of COVID-19 and the treatment I had prescribed myself. I had been religiously taking probiotics to imbue me with immunity for infections like these.1 I believed that lactobacillus acidophilus, the friendly gut bacteria, stimulates the Gut Associated Lymphoid Tissue (GALT) to produce antibodies against virus and bacteria shedding into small intestines and against bacteria abnormally multiplying in the large intestine.2
I was assured by the research of Russian Dr. Elie Metchnikoff on the potent lactobacillus in yogurt (which comprised almost 50% of the Bulgarian diet and made them strong and healthy). Dr. Metchnikoff (who had won the 1908 Nobel Prize in Physiology and Medicine) honored Bulgaria by naming his friendly bacteria lactobacillus bulgaricus.3,4 Dr. Metchnikoff was later honored as the “father of natural immunity.”5
Then came the Spanish flu of 1918-1919 that killed more than 2.5 million Europeans, mostly Italians and British.6 Yet the number of those killed in Bulgaria was as close to that in Switzerland, which was the lowest. Now, the COVID-19 pandemic marched into 2020 killing 4,633 patients out of 82,918 COVID+ in Wuhan, China; 31,855 out of 219,183 COVID+ in Great Britain; 30,560 out of 219,070 COVID+ in Italy; and 80,787 out of 1,367,638 COVID+ in the USA. Ninety-one died of COVID out of 1,965 positive for COVID-19 in Bulgaria.7
I was confident that the lactobacillus acidophilus 20 billion Colony Forming Units (CFU) were stimulating production of the IgG and IgM (from GALT which produces 70% of the body’s immune globulins) needed to neutralize viruses or bacteria.8 The acidophilus produces Vitamin B specially Vit B129 which I believe made for my stronger body. I had prepared myself as I prepared my patients for the flu by consuming Vit C and Zinc. Zinc stimulates the thymus to increase immune responses to viruses.10,11 I was fortified with 2 Colostrum pills daily, preformed sources of IgG and IgA.12
I followed my regimen for acute rhinitis (though there was no nasal obstruction) which meant doing nasal SALINE washing or sprays thrice a day. I knew that the flu virus (or even the SARS-COV2) hides EARLY in the nose and sinuses and is able to produce toxins which inflame the whole body. Worse for SARS-COV2 because these drop into the tonsils and into the lungs. The nasal sprays were meant to reduce the virus numbers (viral load) in the nose and sinuses so there were less shedding. Saline washes decongest the nose to improve breathing. The 60 seconds antiseptic mouthwash followed a regimen of brushing the teeth then the palate and the tonsils and to the base of the tongue. This was to extinguish any virus lurking to go down into the lungs or GIT. This regimen was routine at 3x a day.
The fever dropped slowly. Coughing diminished though the muscles constantly ached after 3 days of Clarithromycin. I was determined to have the COVID tests and a high resolution CT scan of the chest. On March 20 at the hospital ER, I explained I was a patient requesting a CBC, a COVID test, and a chest CT scan and that I will wait for my turn since the ER was full (took me 3 hours). After the interview with the ER physician, I was led to a seat one meter apart from others. Elderly patients with cough all quizzically looked at me in my white doctor’s gown wondering if I was sick. I changed to the gown, mask, and gloves I was provided with when the nurse escorted me to cubicle one. First came the CBC. Next were Rt-PCR swabs of the nose and nasopharynx and of the throat. Finally after the staff sterilized the CT scan room, my scan was completed in a few minutes. The chest scan showed ground glass appearance consistent with Bilateral Basal Pneumonia. I was told that the PCR results would be ready within 7 days.
I was advised urgently by my classmate, a pulmonary specialist from another hospital, for admission for oxygen inhalation and treatment. She went out of her way to look for a pulmonologist but none was available due to quarantine. She looked for an Infectious Disease Specialist who was now in isolation. I requested her that since I was not in respiratory distress and because of my weakened state, I was worried about getting a hospital acquired infection and that I be committed to strict home isolation with treatment prescribed by her. She reluctantly acceded with the admonition that I proceed immediately back to hospital if respiratory difficulties occur. I started the Oseltamivir (Tamiflu) at 2x a day for 5 days and Azithromycin once daily for 7 days plus a mucolytic N- Acetylcysteine 600 mg 2x a day.
There was another dimension beyond my physical stress. I was in MENTAL stress, the pervasive fear of not surviving this that engulfed me. Knowing my close colleagues died from COVID-19 pneumonia after a short battle in ICU with intubation, I realized THIS certainty of death and THAT uncertainty of recovery. I asked for a lifeline from my UP Med ‘76 classmates. (The lifeline in the family was unconditionally given though from a distance). My pulmonologist classmate closely monitored my condition daily. Some offered their listening ears to my echoing worries. Most prayed to God with their unconditional love for me to recover. Another classmate had extraordinary pranic sessions for my healing, my relaxation and my energy.
I reflected on my dad’s advice that in a righteous fight (like against this pneumonia), “you use all means and all ways to win.” I started deep breathing into the nose and slowly out through the mouth knowing full well that the nitric oxide I absorbed through the roof of the nose dilated my coronaries for better heart function and my pulmonary arteries for better oxygen exchange. The deep breathing provided nitric oxide to the bronchus and bronchioles to dilate them for more airflow. Moreover, I was taking in lots of calamansi juices (or lemon or oranges) for its citrulline which has been researched to prolong the effects of nitric oxide.13 These breathing sessions were the MOST IMPORTANT activities if I were to survive and were continuous morning, noon and evening.
Fortunately, I was isolated in 3rd floor Music Room with access to the roof deck garden and fresh air from Laguna de Bay (about 1.5 km from the house in Taguig) and of course, LPs of the Beatles, Aiza and Sharon, and Mozart. I did chest thumping or percussion as far as I could reach my back to loosen the phlegm in my lungs. This self ‘physical therapy’ was 3x a day. I started to spit scanty whitish, thick phlegm.
I made sure that Oseltamivir (Tamiflu) was taken mornings and evenings and the Azithromycin was taken at lunch so there were no drug interactions. The 2 Colostrum tabs were swallowed on waking up. The probiotics were taken after breakfast and after dinner. The Zinc was taken after lunch. Soft stools were present but that was my GIT reacting to the medications.
Adding to the controversy was the new regimen US President Donald Trump was trumpeting on Fox News and CNN. A hospitalist physician treating COVID-19 pneumonias in San Francisco was giving us the new protocols for Chloroquine and Azithromycin, with promising results. He was the classmate of my daughter in UP Med. I went to pharmacies in Taguig and Greenhills for Chloroquine. It was not available. My pulmonologist classmate was firm; “No!” when I suggested the shift. “You will need confinement and an ECG because these combination drugs prolong QTc on electrocardiogram.” This meant Chloroquine and Azithromycin combination may initially precipitate bradycardia (lower heart rate) then ventricular tachycardia (heightened heart rate), and finally, cardiac arrest for senior patients (68 years old) like me with a history of hypertension. This discussion stopped all controversies in treatment.
Moreover, I was getting better. My temperature decreased to 37.8 °C. The muscle pain diminished. The severe point tenderness over the lower ribs persisted. I was deep-breathing which I could not hold for more than 10 seconds. That was not normal! I listened to my lungs for the CRACKLING sounds of pneumonia with my stethoscope. The maze of gurgling and churning sounds from the stomach and intestines seemed to mask the sounds I was listening for. Or was I in denial?
I decided to go back to ER on the 3rd day for a chest X ray. The objective was to see if my pneumonia was progressing. The chest X ray still showed basal pneumonia. I had mixed feelings-- good that pneumonia did not progress to middle lung fields and --- bad that pneumonia was festering.
I completed the 5-day regimen of Oseltamivir (Tamiflu) and was continuing the 8th day of Azithromycin and N-Acetylcysteine when my COVID test finally arrived through email-- I was COVID positive #1906 .
By this time, I was recovering physically and mentally. I had no fever (37.2 °C average), no cough, no sore throat. Breathing was full. I had my appetite back. My outlook was as OPTIMISTIC as the blooming flowers I nurtured during this trial. This timing was fortunate because even with confirmed COVID-19 positive, I knew I had beaten COVID-19 pneumonia at home.
Isolation was completed 2 weeks from my recovery which necessitated another COVID test and rapid test April 10, 2020. This test was still positive. A third PCR done on April 20 was negative for SARSCoV-2. The new DOH protocol was to isolate up to May 5 which I have followed. I am practicing social distancing and wearing a mask.
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"00/00844 A time-based load shedding protection for isolated power systems." Fuel and Energy Abstracts 41, no. 2 (March 2000): 94. http://dx.doi.org/10.1016/s0140-6701(00)90821-x.
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"DETECTION OF FREQUENCY DEVIATION AND UNDER/OVER FREQUENCY PROTECTION BY LOAD SHEDDING USING MATLAB/SIMULINK." International Journal of Advance Engineering and Research Development 2, no. 12 (December 31, 2015). http://dx.doi.org/10.21090/ijaerd.021228.
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Chandak, Sheetal, Pritam Bhowmik, and Pravat Kumar Rout. "Load shedding strategy coordinated with storage device and D-STATCOM to enhance the microgrid stability." Protection and Control of Modern Power Systems 4, no. 1 (November 22, 2019). http://dx.doi.org/10.1186/s41601-019-0138-0.
Full textAbstract:
AbstractRecently microgrids have drawn a potential attraction by fulfilling the environmental demands and the increasing energy demands of the end-users. It is necessary to focus on various protection and control aspects of a microgrid. During the transition between the grid-following and grid-forming modes, the voltage and the frequency instability due to the power mismatch condition becomes the major point of concern. Therefore, the paper executes a frequency-active power and voltage-reactive power drooping control strategy for the precise power-sharing among the distributed power generators. Furthermore, to handle the power deficit scenarios and to maintain the system stability, a system independent and priority-based adaptive three-stage load shedding strategy is proposed. The sensitivity of the strategy depends on the system inertia and is computed according to the varying absolute rate-of-change-of-frequency. The strategy incorporates the operation of battery storage system and distributed static compensator (D-STATCOM) in the microgrid, to provide a reliable power supply to the customers for a considerable time instead of a sudden load shedding. The effectiveness of the proposed strategies is investigated on a scaled-down modified IEEE 13-bus microgrid system on the podium of MATLAB 2015b through the time-domain simulation.