A Methodology for Low-Cost Optimization of Energy Efficient Passive Filters in Distribution Networks

ABSTRACT: In power distribution networks, nonlinear loads produce harmonic currents that can pass through other sensitive locations in the power system and eventually back to the source. Harmonic currents can produce a variety of effects that are harmful to a power system structure. Consequentially, the deployment of new cost and energy efficient passive, active and hybrid filtering techniques is important for the utilities and consumers alike. This paper presents an application of the Genetic Algorithm toolbox (GA) provided by MatLab software in order to find the optimal sizing of parameters of C-type passive filters based on minimization of the total investment cost of the proposed filters. Load power factor (PF), load voltage total harmonic distortion (THD V ) and supply current total demand distortion (TDD) are considered as the main constraints in this paper. Besides, capacitor loading duties are taken into account in compliance with IEEE Standard 18-2002 guidelines. Various numerical results are presented to validate the proposed approach

Ocean Wind Energy Technologies in Modern Electric Networks: Opportunity and Challenges

Wind energy is one of the most important sources of energy in the world. In recent decades, wind as one of the massive marine energy resources in the ocean to produce electricity has been used. This chapter introduces a comprehensive overview of the efficient ocean wind energy technologies, and the global wind energies in both offshore and onshore sides are discussed. Also, the classification of global ocean wind energy resources is presented. Moreover, different components of a wind farm offshore as well as the technologies used in them are investigated. Possible layouts regarding the foundation of an offshore wind turbine, floating offshore, as well as the operation of wind farms in the shallow and deep location of the ocean are studied. Finally, the offshore wind power plant challenges are described

Optimal C-type Filter for Harmonics Mitigation and Resonance Damping in Industrial Distribution Systems

Single-tuned passive filters offer reasonable mitigation for harmonic distortion at a specific harmonic frequency with a high filtering percentage, but resonance hazards exist. Traditional damped filters offer high-pass filtering for the high-frequency range, but suffer from extra ohmic losses. C-type filters may operate in a manner similar to the tuned filters with low damping losses and marginal resonance damping capabilities. Also, they can be designed as damped filters with increased resonance damping capability. In this paper, a methodology that facilitates sizing for the C-type damped filter parameters for harmonics mitigation and resonance damping in balanced distribution system networks, is presented and discussed using the impedance-frequency index. This index evaluates the resonance damping capability provided by the damped filters analytically rather than the conventional graphical method of impedance-frequency scanning. It shows how to size shunt passive filters, while making a full use of their damping capabilities. It can disclose the parallel resonance frequencies of the equivalent system-filter impedance. A comparative study of the new approach and a conventional filter design approach, which aims to minimize total harmonic current distortion, is presented. Numerous simulation results are provided to clarify the proposed methodology, advantages, and disadvantages

Osteogenic Differentiation Potential of Human Bone Marrow and Amniotic Fluid-Derived Mesenchymal Stem Cells in Vitro & in Vivo

BACKGROUND: Cell therapies offer a promising potential in promoting bone regeneration. Stem cell therapy presents attractive care modality in treating degenerative conditions or tissue injuries. The rationale behind this is both the expansion potential of stem cells into a large cell population size and its differentiation abilities into a wide variety of tissue types, when given the proper stimuli. A progenitor stem cell is a promising source of cell therapy in regenerative medicine and bone tissue engineering. AIM: This study aimed to compare the osteogenic differentiation and regenerative potentials of human mesenchymal stem cells derived from human bone marrow (hBM-MSCs) or amniotic fluid (hAF-MSCs), both in vitro and in vivo studies. SUBJECTS AND METHODS: Human MSCs, used in this study, were successfully isolated from two human sources; the bone marrow (BM) and amniotic fluid (AF) collected at the gestational ages of second or third trimesters. RESULTS: The stem cells derived from amniotic fluid seemed to be the most promising type of progenitor cells for clinical applications. In a pre-clinical experiment, attempting to explore the therapeutic application of MSCs in bone regeneration, Rat lumbar spines defects were surgically created and treated with undifferentiated and osteogenically differentiated MSCs, derived from BM and second trimester AF. Cells were loaded on gel-foam scaffolds, inserted and fixed in the area of the surgical defect. X-Ray radiography follows up, and histopathological analysis was done three-four months post- operation. The transplantation of AF-MSCs or BM-MSCs into induced bony defects showed promising results. The AF-MSCs are offering a better healing effect increasing the likelihood of achieving successful spinal fusion. Some bone changes were observed in rats transplanted with osteoblasts differentiated cells but not in rats transplanted with undifferentiated MSCs. Longer observational periods are required to evaluate a true bone formation. The findings of this study suggested that the different sources; hBM-MSCs or hAF-MSCs exhibited remarkably different signature regarding the cell morphology, proliferation capacity and osteogenic differentiation potential CONCLUSIONS: AF-MSCs have a better performance in vivo bone healing than that of BM-MSCs. Hence, AF derived MSCs is highly recommended as an alternative source to BM-MSCs in bone regeneration and spine fusion surgeries. Moreover, the usage of gel-foam as a scaffold proved as an efficient cell carrier that showed bio-compatibility with cells, bio-degradability and osteoinductivity in vivo

Development of Liposomal Gemcitabine with High Drug Loading Capacity

Liposomes are widely used for systemic delivery of chemotherapeutic agents to reduce their nonspecific side effects. Gemcitabine (Gem) makes a great candidate for liposomal encapsulation due to the short half-life and nonspecific side effects; however, it has been difficult to achieve liposomal Gem with high drug loading capacity. Remote loading, which uses a transmembrane pH gradient to induce an influx of drug and locks the drug in the core as a sulfate complex, does not serve Gem as efficiently as doxorubicin (Dox) due to the low pKa value of Gem. Existing studies have attempted to improve Gem loading capacity in liposomes by employing lipophilic Gem derivatives or creating a high-concentration gradient for active loading into the hydrophilic cores (small volume loading). In this study, we combine the remote loading approach and small volume loading or hypertonic loading, a new approach to induce the influx of Gem into the preformed liposomes by high osmotic pressure, to achieve a Gem loading capacity of 9.4–10.3 wt % in contrast to 0.14–3.8 wt % of the conventional methods. Liposomal Gem showed a good stability during storage, sustained-release over 120 h in vitro, enhanced cellular uptake, and improved cytotoxicity as compared to free Gem. Liposomal Gem showed a synergistic effect with liposomal Dox on Huh7 hepatocellular carcinoma cells. A mixture of liposomal Gem and liposomal Dox delivered both drugs to the tumor more efficiently than a free drug mixture and showed a relatively good anti-tumor effect in a xenograft model of hepatocellular carcinoma. This study shows that bioactive liposomal Gem with high drug loading capacity can be produced by remote loading combined with additional approaches to increase drug influx into the liposomes

Active management of the third stage of labour without controlled cord traction: a randomized non-inferiority controlled trial

BACKGROUND: The third stage of labour refers to the period between birth of the baby and complete expulsion of the placenta. Some degree of blood loss occurs after the birth of the baby due to separation of the placenta. This period is a risky period because uterus may not contract well after birth and heavy blood loss can endanger the life of the mother. Active management of the third stage of labour (AMTSL) reduces the occurrence of severe postpartum haemorrhage by approximately 60-70%. Active management consists of several interventions packaged together and the relative contribution of each of the components is unknown. Controlled cord traction is one of those components that require training in manual skill for it to be performed appropriately. If it is possible to dispense with controlled cord traction without losing efficacy it would have major implications for effective management of the third stage of labour at peripheral levels of health care. OBJECTIVE: The primary objective is to determine whether the simplified package of oxytocin 10 IU IM/IV is not less effective than the full AMTSL package. METHODS: A hospital-based, multicentre, individually randomized controlled trial is proposed. The hypothesis tested will be a non-inferiority hypothesis. The aim will be to determine whether the simplified package without CCT, with the advantage of not requiring training to acquire the manual skill to perform this task, is not less effective than the full AMTSL package with regard to reducing blood loss in the third stage of labour.The simplified package will include uterotonic (oxytocin 10 IU IM) injection after delivery of the baby and cord clamping and cutting at approximately 3 minutes after birth. The full package will include the uterotonic injection (oxytocin 10 IU IM), controlled cord traction following observation of uterine contraction and cord clamping and cutting at approximately 3 minutes after birth. The primary outcome measure is blood loss of 1000 ml or more at one hour and up to two hours for women who continue to bleed after one hour. The secondary outcomes are blood transfusion, the use of additional uterotonics and measure of severe morbidity and maternal death.We aim to recruit 25,000 women delivering vaginally in health facilities in eight countries within a 12 month recruitment period. MANAGEMENT: Overall trial management will be from HRP/RHR in Geneva. There will be eight centres located in Argentina, Egypt, India, Kenya, Philippines, South Africa, Thailand and Uganda. There will be an online data entry system managed from HRP/RHR. The trial protocol was developed following a technical consultation with international organizations and leading researchers in the field. EXPECTED OUTCOMES: The main objective of this trial is to investigate whether a simplified package of third stage management can be recommended without increasing the risk of PPH. By avoiding the need for a manual procedure that requires training, the third stage management can be implemented in a more widespread and cost-effective way around the world even at the most peripheral levels of the health care system. This trial forms part of the programme of work to reduce maternal deaths due to postpartum haemorrhage within the RHR department in collaboration with other research groups and organizations active in the field. TRIAL REGISTRATION: ACTRN12608000434392

Following 411 Cochrane Protocols to Completion: A Retrospective Cohort Study

Cochrane reviews are regarded as being scientifically rigorous and are increasingly used by a variety of stakeholders. However, factors predicting the publication of Cochrane reviews have never been reported. This is important because if a higher proportion of Cochrane protocols with certain characteristics (e.g., funding) are being published, this may lead to inaccurate decisions. We examined the frequency of published and unpublished Cochrane reviews and protocol factors that predict the publication of Cochrane reviews.Retrospective cohort study of Cochrane protocols published in 2000 (Issues 2 to 4) and 2001 (Issue 1). The publication status of these reviews was followed up to Issue 1, 2008 in The Cochrane Library. Survival analysis of the time from protocol publication to the first review publication and protocol factors predicting the time to publication was conducted. There were 411 new Cochrane protocols in the cohort. After excluding 39; 71/372 (19.1%) were unpublished and 301/372 (80.9%) were published as full Cochrane reviews at the time of study analysis (January 2008). The median time to publication was 2.4 years (range: 0.15 to 8.96). Multivariate analyses revealed that shorter time to publication was associated with the review subsequently being updated (hazard ratio, HR: 1.80 [95% confidence interval, CI: 1.39 to 2.33 years]) and longer time to publication was associated with the review having two published protocols, indicating changes to the review plan (HR: 0.33 [95% CI: 0.12 to 0.90 years]).Only about 80% Cochrane protocols were published as full reviews after over 8 years of follow-up. The median time to publication was 2.4 years and some reviews took much longer. Strategies to decrease time to publication should be considered, such as streamlining the review process, increased support for authors when protocol amendments occur, and better infrastructure for updating Cochrane reviews

Misoprostol in addition to routine treatment of postpartum hemorrhage: A hospital-based randomized-controlled trial in Karachi, Pakistan

<p>Abstract</p> <p>Background</p> <p>Postpartum hemorrhage (PPH) remains a major killer of women worldwide. Standard uterotonic treatments used to control postpartum bleeding do not always work and are not always available. Misoprostol's potential as a treatment option for PPH is increasingly known, but its use remains ad hoc and available evidence does not support the safety or efficacy of one particular regimen. This study aimed to determine the adjunct benefit of misoprostol when combined with standard oxytocics for PPH treatment.</p> <p>Methods</p> <p>A randomized controlled trial was conducted in four Karachi hospitals from December 2005 – April 2007 to assess the benefit of a 600 mcg dose of misoprostol given sublingually in addition to standard oxytocics for postpartum hemorrhage treatment. Consenting women had their blood loss measured after normal vaginal delivery and were enrolled in the study after losing more than 500 ml of blood. Women were randomly assigned to receive either 600 mcg sublingual misoprostol or matching placebo in addition to standard PPH treatment with injectable oxytocics. Both women and providers were blinded to the treatment assignment. Blood loss was collected until active bleeding stopped and for a minimum of one hour after PPH diagnosis. Total blood loss, hemoglobin measures, and treatment outcomes were recorded for all participants.</p> <p>Results</p> <p>Due to a much lower rate of PPH than expected (1.2%), only sixty-one patients were diagnosed and treated for their PPH in this study, and we were therefore unable to measure statistical significance in any of the primary endpoints. The addition of 600 mcg sublingual misoprostol to standard PPH treatments does, however, suggest a trend in reduced postpartum blood loss, a smaller drop in postpartum hemoglobin, and need for fewer additional interventions. Women who bled less overall had a significantly smaller drop in hemoglobin and received fewer additional interventions. There were no hysterectomies or maternal deaths among study participants. The rate of transient shivering and fever was significantly higher among women receiving misoprostol</p> <p>Conclusion</p> <p>A 600 mcg dose of misoprostol given sublingually shows promise as an adjunct treatment for PPH and its use should continue to be explored for its life-saving potential in the care of women experiencing PPH.</p> <p>Trial Registration</p> <p>Clinical trials.gov, Registry No. NCT00116480</p

How effective are the components of active management of the third stage of labor?

BACKGROUND: Active management of the third stage of labor is recommended for the prevention of post-partum hemorrhage and commonly entails prophylactic administration of a uterotonic agent, controlled cord traction, and uterine massage. While oxytocin is the first-choice uterotonic, it is not known whether its effectiveness varies by route of administration. There is also insufficient evidence regarding the value of controlled cord traction or uterine massage. This analysis assessed the independent and combined effectiveness of all three interventions, and the effect of route of oxytocin administration on post-partum blood loss. METHODS: Secondary data were analyzed from 39202 hospital-based births in four countries and two clinical regimens: one in which oxytocin was administered following delivery of the baby; the other in which it was not. We used logistic regression to examine associations between clinical and demographic variables and post-partum blood loss ≥ 700 mL. RESULTS: Among those with no oxytocin prophylaxis, provision of controlled cord traction reduced hemorrhage risk by nearly 50% as compared with expectant management (P < 0.001). Among those with oxytocin prophylaxis, provision of controlled cord traction reduced hemorrhage risk by 66% when oxytocin was intramuscular (P < 0.001), but conferred no benefit when oxytocin was intravenous. Route of administration was important when oxytocin was the only intervention provided: intravenous administration reduced hemorrhage risk by 76% as compared with intramuscular administration (P < 0.001); when combined with other interventions, route of administration had no effect. In both clinical regimens, uterine massage was associated with increased hemorrhage risk. CONCLUSIONS: Recommendations for active management of the third stage of labor should account for setting-related differences such as the availability of oxytocin and its route of administration. The optimal combination of interventions will vary accordingly