2,210 research outputs found
Short and Long Term Energy Storage for Enhanced Resilience of Electric Infrastructures Storage of Compressed Hydrogen and Oxygen Gasses Derived From Electrolysis to Provide Grid Connected Mechanical and Electrochemical Electrical Power Generation on Demand
Energy storage based upon converting electricity from water to hydrogen gas provides a solution to the problem of intermittency in renewable energy systems. These benefits are not specific to isolated solar and wind energy production but can also be derived as a complement to load and demand variations on the fully integrated electrical grid. The main components of this system are electrolytic cells, which use electricity to generate hydrogen and oxygen from water, compressed gas hydrogen and oxygen storage tanks and fuel cells, which recombine hydrogen with oxygen to generate electricity. At times of excess energy availability, electrolytic cells are used as a controllable load by which the excess energy is converted into hydrogen and oxygen gas. When there is insufficient energy to meet demands, the fuel cell is used to recombine hydrogen and oxygen into water and create electricity. Water storage and compressed gasses can be used to further tune the load. Water can be pumped from one reservoir to another to create artificial demand, and can be allowed to flow by gravitational power to create electricity on demand. Compressed gasses can similarly be managed to create load or increase generation capacity at will. These complements are key to effectively managing electrolytic cell arrays for maximum potential, but also provide for very high versatility and resilience of the system, which can allow operators to micro-manage electrical supplies and demands. This work examines the technical details of such systems and extracts some of the lessons learned from more than fifty years of related research, prototyping and implementations
Delayed onset muscle soreness: No pain, no gain? The truth behind this adage
The purpose of this article is to provide brief insight into delayed onset muscle soreness (DOMS), a phenomenon that is often experienced by recreational and elite athletes. The negative implications of DOMS include pain, decreased motivation to continue training, and decreased performance. While performance issues may be more relevant to the elite athlete, pain and decreased motivation are particularly relevant to recreational athletes wishing to sustain a regular level of physical activity. The article is aimed at general practitioners (GPs) who may encounter athletes presenting with DOMS, and who will benefit from understanding the proposed mechanisms, signs and symptoms of the condition. Numerous researchers have hypothesised that certain interventions may prevent or minimise the symptoms thereof, and all GPs could benefit from understanding the available options for athletes, and the scientific evidence that supports these options.Keywords: delayed onset muscle soreness, mechanism, symptoms, treatment, athletes, managemen
Evidence-based prescription for cyclo-oxygenase-2 inhibitors in sports injuries
Healthcare professionals are increasingly under pressure to return athletes to play in the shortest possible time. There is limited choice in providing treatment that speeds up tissue repair, while simultaneously maintaining good quality of healing. Inflammation forms a fundamental part in the process of tissue repair. However, excessive inflammation may cause more pain, and limit functional restoration. Although the use of anti-inflammatory treatment in the form of a cyclo-oxygenase-2 inhibitor (coxibs) has been widely recognised as being effective, the potential detrimental effect on tissue repair, as described mainly in animal model studies, needs to be taken into account. The side-effects profile on the gastrointestinal tract favour coxibs over non-traditional NSAIDs. The possible effects on the renal and cardiovascular systems also need to be considered. The prescription of coxibs should be pathology and situation specific. There are no clear guidelines on the correct time of administration and the duration of the course, but it seems that the literature is in agreement that they should be administered for a limited time at the lowest effective dose possible.Keywords: cyclo-oxygenase-2 inhibitors (coxibs), sports injuries, treatmen
Interrater reliability of electrodiagnosis in neonatal brachial plexopathy
Introduction: We investigated interrater reliability of overall assessment of nerve root lesions by electrodiagnostic testing (EDX) in neonatal brachial plexus palsy (NBPP). Methods: Two blinded, boardâ certified reviewers retrospectively reviewed deâ identified EDX data from 37 infants with NBPP for 2005â 2012. Only nerve conduction and electromyography needle data were included. The examiners independently assigned 1 of 4 nerve root lesion categories: (1) preâ ganglionic lesion (avulsion), (2) postâ ganglionic lesion (rupture), (3) normal, or (4) â unable to determine.â Simple percentage agreement, the Cohen kappa statistic representing interrater reliability for each nerve root (C5â T1), and overall kappa between examiners were evaluated. Results: Interrater reliabilities were substantial to almost perfect for each nerve root except C5. Considering all nerve roots, overall interrater reliability was substantial (kappa = 0.62); simple percentage agreement was 75% (138/185). Conclusions: Interrater reliability of nerve root assessment by EDX for infants with NBPP was high for C6â T1 root levels, but less reliable for C5 because of technical factors. Muscle Nerve 55: 69â 73, 2017Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135308/1/mus25193.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135308/2/mus25193_am.pd
Shouldering the blame for impingement: the rotator cuff continuum
The aim of this article was to summarise recent research on shoulder impingement and rotator cuff pathology. A continuum model of rotator cuff pathology is described, and the challenges of accurate clinical diagnosis, imaging and best management discussed.Keywords: shoulder impingement syndrome, subacromial impingement syndrome, rotator cuff, tendinopathy, rehabilitatio
Case study in six sigma methadology : manufacturing quality improvement and guidence for managers
This article discusses the successful implementation of Six Sigma methodology in a high precision and critical process in the manufacture of automotive products. The Six Sigma define–measure–analyse–improve–control approach resulted in a reduction of tolerance-related problems and improved the first pass yield from 85% to 99.4%. Data were collected on all possible causes and regression analysis, hypothesis testing, Taguchi methods, classification and regression tree, etc. were used to analyse the data and draw conclusions. Implementation of Six Sigma methodology had a significant financial impact on the profitability of the company. An approximate saving of US$70,000 per annum was reported, which is in addition to the customer-facing benefits of improved quality on returns and sales. The project also had the benefit of allowing the company to learn useful messages that will guide future Six Sigma activities
Evolutionary Dead End in the Galápagos: Divergence of Sexual Signals in the Rarest of Darwin's Finches
Understanding the mechanisms underlying speciation remains a challenge in evolutionary biology. The adaptive radiation of Darwin's finches is a prime example of species formation, and their study has revealed many important insights into evolutionary processes. Here, we report striking differences in mating signals (songs), morphology and genetics between the two remnant populations of Darwin's mangrove finch Camarhynchus heliobates, one of the rarest species in the world. We also show that territorial males exhibited strong discrimination of sexual signals by locality: in response to foreign songs, males responded weaker than to songs from their own population. Female responses were infrequent and weak but gave approximately similar results. Our findings not only suggest speciation in the mangrove finch, thereby providing strong support for the central role of sexual signals during speciation, but they have also implications for the conservation of this iconic bird. If speciation is complete, the eastern species will face imminent extinction, because it has a population size of only 5–10 individuals
Structural basis for Fullerene geometry in a human endogenous retrovirus capsid
The HML2 (HERV-K) group constitutes the most recently acquired family of human endogenous retroviruses, with many proviruses less than one million years old. Many maintain intact open reading frames and provirus expression together with HML2 particle formation are observed in early stage human embryo development and are associated with pluripotency as well as inflammatory disease, cancers and HIV-1 infection. Here, we reconstruct the core structural protein (CA) of an HML2 retrovirus, assemble particles in vitro and employ single particle cryogenic electron microscopy (cryo-EM) to determine structures of four classes of CA Fullerene shell assemblies. These icosahedral and capsular assemblies reveal at high-resolution the molecular interactions that allow CA to form both pentamers and hexamers and show how invariant pentamers and structurally plastic hexamers associate to form the unique polyhedral structures found in retroviral cores
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