163 research outputs found

    Heightened reliability concerns in the distribution transformers market amidst the energy transition

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    Distribution transformers are an important part of the electricity grid as they regulate the voltage levels as required. As these transformers have to operate under extreme conditions, including extreme temperatures, overloading, voltage fluctuations and natural calamities, the original equipment manufacturers are required to implement robust design considerations. These design considerations are crucial for offshore wind applications where distribution transformers operate in a remote and harsh marine environment. Once the design considerations are adopted by the OEMs, it is expected that the performance and lifespan of distribution transformers will increase, which will improve the reliability of the overall power system in the long run

    Preferences for Developing Undergraduate Research in Pakistani Universities: Student Teachers’ Perspective

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    Undergraduate Research (UGR) is an important component in the curriculum of good ranking universities at present. It encompasses a continuous process of research engagements during undergraduate studies. Involving undergraduate students in research helps in linking theory to practice, understanding research processes and determining career choices. However, promoting UGR in universities in Pakistan requires proper consideration and planning. This study was aimed at identifying research preferences of undergraduate students and improving UGR in Pakistani universities. As students are the most important stakeholder in UGR, the data were collected from 2168 undergraduate students randomly selected from four large universities in Rawalpindi-Islamabad. The research instrument used was a questionnaire developed, pilot tested and validated before its use in this study. The data were converted into percentages and crosstabs using SPSS to analyze data. We found that undergraduate students expressed strong preference for research involvement and were willing to work any part of the week for gaining research experience. The students preferred field research as compared to research in lab or desk work. The students’ views and preferences on crosstabs helped in devising strategies for improving UGR in universities in Pakistan

    Phloem transport in the stolon of Saxifraga sarmentosa

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    A study was made of assimilates and ionic tracer movementalong the stolon of Saxifraga sarmentosa. When ionic tracers or 14 C-sucrose are applied to the transloadting stolon they undergo a longdistance transport which is strictly polarised, with a short-distance movement which is symmetrical with respect to the point of application. The distribution along the axis after a suitable length of time shows an accurate exponential fall-off pattern, except with naturally assimilated or applied 14C-sucrose where it is fairly level. In this case the linear velocity of movement was estimated as about 20 cm h-1. Transport of materials is readily reversible by interchanging the roles of parent and daughter plants as source and sink. The transpiration stream can be similarly reversed. By these means it was confirmed that 14 C-assimilates and 137Cs move in the phloem, whereas 89Sr moves in the xylem. The sieve tubes are thus not inherently polarised in this organ. Inhibitors such as nitrogen, cyanide and DNP applied overlengths of 20--30 cm exert a more or less complete and reversible inhibition of the movement of 14C-assimilates and 137Cs. Cyanide gas is considerably more effective than solution. A variety of approaches, including the use of 14C-cyanide, confirmed that the inhibition was effective in the sieve tubes themselves, and not merely at the terminal sites. Electron microscopic examination showed that callosing in the sieve plates was not involved; however, in all cases, including the normal one, the sieve plate pores appeared blocked with P-protein.Tests with Valinonycin which possesses a particular affinity for potassium, were ineffective. This may have been due to its insolubility in water and to the large size of the molecule. Comparative studies were carried out by applying two ionic tracers together. These gave consistent and precise results in termsof the slopes of the plots log activity against distance Of the tracers used (22Na, 42K, 86Rb, 137Cs and 82Br) the comparison of 137Cs and 82Br was perhaps the most interesting; the anion is transported more or less equally with the cation, but its lateral leakage appears to be less. The results of this study provide a well-established case for the following conclusions relevant to the controversy over mechanism: (1) Phloem transport in the stolon is strictly unidirectional. (2) Nitrogen, Cyanide and DNP exert a strong effect localised in the sieve tubes themselves (as well as at the terminals); it is reversible. (3) The inhibition of transport is not due to callose blockage. (4.) Anion transport follows a similar pattern to cation. These conclusions are very adverse to the Munch hypothesis, and to any diffusion-analogue theory; they favour a theory of activemass flow. The electro-osmotic theory faces the difficulty of anion transport.<p

    neurostimulation for refractory primary chronic headache disorders: a review

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    Headache is the commonest symptom seen in both primary and secondary care. Vast majority are primary i.e. for which no underlying cause has been detected. Tension Headaches, Migraine and Cluster Headaches are the most common primary headache disorders in the population. Although most of the primary headache disorders can be satisfactorily treated with both acute and preventive medications, those that are refractory to conventional treatment pose a great challenge to the headache physician. Moreover some patients are not able to use traditional treatment due to intolerance and co-morbidities. Neurostimulation is a treatment modality that has been used in other neurological disorders such as movement disorders, multiple sclerosis and chronic neuropathic pain and there has been emerging evidence to its usefulness in primary headache disorders. These range from being invasive treatments like deep brain stimulation to minimally invasive one like occipital nerve stimulators. Non-invasive neurostimulation is gradually emerging as a potential non-pharmaceutical option in managing primary headache disorders. The article reviews the evidence of Neurostimulation in primary headache disorders with a view to ascertain its efficacy and safety

    Images depicting headache pain – a tool to aid the diagnosis of cluster headache: a pilot study

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    Introduction and objective: The diagnosis of primary headaches is based on the International Classification of Headache Disorders (ICHD-3). Cluster headache (CH), a debilitating primary headache, is often misdiagnosed as migraine. In the absence of biological markers, a new visual screening tool with images depicting pain could aid the correct diagnosis of CH. The objective of the study is to test the tool on healthy participants and participants with CH and migraine.Methods: In phase 1, 6 images portraying people with pain were tested on 150 healthy participants. The healthy participants were asked to rate the images as mild, moderate, severe or excruciating pain. In phase 2, the images were further tested on 116 participants with headache (16 participants with CH, 100 participants with migraine). The participants were recruited prospectively from a tertiary headache center between February and May 2017. The participants were asked to choose which image best illustrated their headache attacks.Results: Phase 1 results showed that the images represent a range of headache pain severities from mild to excruciating as rated by healthy participants. They rated two images as excruciating, one image as severe, one image as moderate/severe, one image as moderate and one image as mild. Phase 2 results showed that two-thirds of participants with CH (69%) and half of the participants with migraine (52%) chose an image described as excruciating by the healthy participants.Conclusion: We developed a screening tool with six drawings depicting headache pain severities from mild to excruciating as rated by the healthy participants. Although the images did not differentiate between CH and migraine, the study indicated the potential of using visual aids to assess headache severity

    Update on the pathophysiology of cluster headache: Imaging and neuropeptide studies

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    Objective: Cluster headache (CH) is the most severe primary headache condition. Its pathophysiology is multifaceted and incompletely understood. This review brings together the latest neuroimaging and neuropeptide evidence on the pathophysiology of CH.Methods: A review of the literature was conducted by searching PubMed and Web of Science. The search was conducted using the following keywords: imaging studies, voxel-based morphometry, diffusion-tensor imaging, diffusion magnetic resonance imaging, tractography, connectivity, cerebral networks, neuromodulation, central modulation, deep brain stimulation, orexin-A, orexin-B, tract-based spatial statistics, single-photon emission computer tomography studies, positron-emission tomography, functional magnetic resonance imaging, magnetic resonance spectroscopy, trigeminovascular system, neuropeptides, calcitonin gene-related peptide, neurokinin A, substance P, nitric oxide synthase, pituitary adenylate cyclase-activating peptide, vasoactive intestinal peptide, neuropeptide Y, acetylcholine, noradrenaline, and ATP. “Cluster headache” was combined with each keyword for more relevant results. All irrelevant and duplicated records were excluded. Search dates were from October 1976 to May 2018.Results: Neuroimaging studies support the role of the hypothalamus in CH, as well as other brain areas involved in the pain matrix. Activation of the trigeminovascular system and the release of neuropeptides play an important role in CH pathophysiology. Among neuropeptides, calcitonin gene-related peptide, vasoactive intestinal peptide, and pituitary adenylate cyclase-activating peptide have been reported to be reliable biomarkers for CH attacks, though not specific for CH. Several other neuropeptides are involved in trigeminovascular activation, but the current evidence does not qualify them as reliable biomarkers in CH.Conclusion: CH has a complex pathophysiology and the pain mechanism is not completely understood. Recent neuroimaging studies have provided insight into the functional and structural network bases of CH pathophysiology. Although there has been important progress in neuropeptide studies, a specific biomarker for CH is yet to be found

    General physicians\u27 perspective of sleep apnea from a developing country

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    To assess the knowledge of general physicians about the diagnosis and management of obstructive sleep apnea (OSA), a self-administered questionnaire, containing 15 questions, was distributed to 160 doctors attending a pulmonary CME program in March 2002. After 15 minutes of response time, the questionnaires were collected. The data were entered and analyzed using SPSS (Version 10.0) software. One hundred and twenty (75%) questionnaires were returned. Only 41% of responders had ever read an article about OSA and 36% had suspected it at least once in their practice. The majority (61-77%) of responders were aware of the common symptoms of OSA, but 55% did not recognize its association with hypertension. A significant number of doctors were not aware that OSA could occur in non-obese individuals (33%), women (42%) and children (39%). Only 25% of responders recognized that a history and blood tests were insufficient to make a reliable diagnosis of OSA. Half of the responders were aware of CPAP therapy for OSA, whereas 18% would have prescribed sedatives to treat sleep disturbances in OSA

    Characterization of cypermethrin degrading bacteria: A hidden micro flora for biogeochemical cycling of xenobiotics

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     Background: Cypermethrin is a Synthetic Pyrethroid (SP) having widespread applications in agriculture and industrial sector especially in sheep dip formulations and tanneries. Rhizoremediation offers a sustainable, environment-friendly and cost-effective means to carry out remediation of contaminated soils.Methods: Six bacterial strains were screened out and characterized at various doses of cypermethrin, heavy metal salts and antibiotics. The optimum growth conditions were determined for these bacterial isolates. The degradation of cypermethrin was confirmed through the growth of bacteria on minimal media (BHB) with cypermethrin and thin layer chromatographic analysis; retention factor values (Rf) were calculated and compared with standard Rf values.Results: Growth curve experiments revealed that three bacterial isolates were able to grow in the presence of cypermethrin. Tolerance to the high concentration of heavy metal salts (300µgmL-1) and resistance towards different antibiotics was observed in all three bacterial isolates indicating a positive correlation between pesticide degradation and tolerance to metals and antibiotics. Bacterial strains A-C1 and B-B2 were identified as Xanthomonas maltophilia and B-C2 as Acinetobacter sp. Cypermethrin degradation occurred concomitant with bacterial growth reaching an optical density (OD600) up to 0.869.Conclusion: Microbes present in rhizosphere have potential to mineralize the pesticides. A significant biodegradation of the cypermethrin was observed based on above mentioned lab parameters. These results paved the way for designing a multi-resistant bacterium that can be used to reverse the altered environment
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