637 research outputs found

    The impact of Stieltjes' work on continued fractions and orthogonal polynomials

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    Stieltjes' work on continued fractions and the orthogonal polynomials related to continued fraction expansions is summarized and an attempt is made to describe the influence of Stieltjes' ideas and work in research done after his death, with an emphasis on the theory of orthogonal polynomials

    Transition probabilities for general birth-death processes with applications in ecology, genetics, and evolution

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    A birth-death process is a continuous-time Markov chain that counts the number of particles in a system over time. In the general process with nn current particles, a new particle is born with instantaneous rate λn\lambda_n and a particle dies with instantaneous rate μn\mu_n. Currently no robust and efficient method exists to evaluate the finite-time transition probabilities in a general birth-death process with arbitrary birth and death rates. In this paper, we first revisit the theory of continued fractions to obtain expressions for the Laplace transforms of these transition probabilities and make explicit an important derivation connecting transition probabilities and continued fractions. We then develop an efficient algorithm for computing these probabilities that analyzes the error associated with approximations in the method. We demonstrate that this error-controlled method agrees with known solutions and outperforms previous approaches to computing these probabilities. Finally, we apply our novel method to several important problems in ecology, evolution, and genetics

    Integrated Approach for Developing Agile Strategy

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    Thep rojectl ooksa t Agility andA gile manufacturingin particular,w ith a focuso n the SME type businessT. he initial focus is on the developmenot f the ASF (Agile Strategic Framework) to make the selection of tools and techniques for manufacturing environments automated and systematised. This is to give consistency of approach, repeatability and to develop the system automation potential. This work will produce a test type model of how the business environment audit tool can be automated to produce results quickly and easily with less human time and intervention. One part of the ASF which needs particular development is the process of examining a company strategy from an agility type perspective. The project fills this niche by looking at how agility fits with traditional schools of strategy, how it relates to definitions of agility from content analysis and pulls these together. Using grounded theory and qualitative methods to examine the meanings, usage and context of Agility an examination of how this may relate to TRIZ type systems using agility paradigms is undcrtaken. This particular study relates to agility in a large context including software, construction and business processes as well as manufacturing definitions. A working model with Case Study examples is suggested as a point for further development

    Screening the Efficacy of Some Traditional Herbal Drugs for Treatment of Hymenolepis diminuta Infection in Rats

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    Background: Hymenolepis nana (human infecting tapeworm) and H. diminuta (rodent infecting tapeworm) are currently incriminated to be the cause of non-specific bowel disturbances. They are in most instances resistant to the available anticestodal compounds due to misuse of drugs and probably adaptation of the parasites to the commercially available drugsObjective: Our objective is to study the toxicity and curative efficacy of different medicinal plants that are candidate for the treatment of tapeworm infections in man.Methods: Four medicinal plants were tested for their ability to treat Hymenolepis diminuta tapeworm infection in rats. These plants are Amaranthus viridis, Cucurbita maxima, Hagenia abyssinica and Balanites aegyptiaca. Selection of these plants was based on ethnobotanicalinformation. The evaluation of the efficiency of these medicinal plants was based on the “controlled test design”, modified from Moskey and Harwood10: Following pre-infection screening, and life cycle establishment rats were grouped to six experimental groups for each plant. Stool specimens were collected from all groups, the mean of eggs counts per gram of faeces were counted. The reduction percentage of eggs per gram (EPG) was calculated and time to clear eggs was compared with that of Niclosamide. Niclosamide drug was used in this study as a control treatment14.Results: There were no signs of toxic effect on the rats due to administration of any of the tested medicinal plants. Amaranthus viridis leavs exhibited a very weak efficacy. It did not reduce eggs ineither water or food significantly as compared to the untreated control group (p> 0.05). The deparasitization activity of this plant (35%) was not significant. Similarly, Balanites aegyptiaca seeds were not effective in treatment of the infection in rats. Egg counts and deparasitization infood and water, were not significantly (p> 0.05) different from those of the untreated control group. On the other hand, Cucurbita maxima and Hagenia abyssinica seeds were very effective in the treatment of Hymenolepis diminuta infection in rats. Egg reduction (100%) was highly significant (p< 0.01) in food and water as compared to that of the untreated control group of rats (zero%). C. maxima seeds in food deparasitized 80% of the worms, while Hagenia abyssinica deparasitized 100%.Conclusion: Our conclusion was that Hagenia abyssinica was the most active plant of this group in the treatment of Hymenolepis diminuta infection in rats

    An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

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    Supplementary information is available online at: https://static-content.springer.com/esm/art%3A10.1038%2Fsrep41935/MediaObjects/41598_2017_BFsrep41935_MOESM25_ESM.pdf .Copyright © The Author(s) 2017. A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH 4 H 2 PO 4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH 4) 3 Al 5 H 6 (PO 4) 8.18H 2 O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al 3 (PO 4) 2 (OH) 3 (H 2 O) 5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT and Future Planning (No. 2015R1A5A1037548)

    Interference management for moving networks in ultra-dense urban scenarios

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    The number of users relying on broadband wireless connectivity while riding public transportation vehicles is increasing significantly. One of the promising solutions is to deploy moving base stations on public transportation vehicles to form moving networks (MNs) that serve these vehicular users inside the vehicles. In this study, we investigated the benefits and challenges in deploying MNs in ultra-dense urban scenarios. We identified that the key challenge limiting the performance of MNs in ultra-dense urban scenarios is inter-cell interference, which is exacerbated by the urban canyon effects. To address this challenge, we evaluated different inter-cell interference coordination and multi-antenna interference suppression techniques for MNs. We showed that in using MNs together with effective interference management approaches, the quality of service for users in vehicles can be significantly improved, with negligible impacts on the performance of regular outdoor users

    IceCube-Gen2: A Vision for the Future of Neutrino Astronomy in Antarctica

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    20 pages, 12 figures. Address correspondence to: E. Blaufuss, F. Halzen, C. Kopper (Changed to add one missing author, no other changes from initial version.)20 pages, 12 figures. Address correspondence to: E. Blaufuss, F. Halzen, C. Kopper (Changed to add one missing author, no other changes from initial version.)20 pages, 12 figures. Address correspondence to: E. Blaufuss, F. Halzen, C. Kopper (Changed to add one missing author, no other changes from initial version.)The recent observation by the IceCube neutrino observatory of an astrophysical flux of neutrinos represents the "first light" in the nascent field of neutrino astronomy. The observed diffuse neutrino flux seems to suggest a much larger level of hadronic activity in the non-thermal universe than previously thought and suggests a rich discovery potential for a larger neutrino observatory. This document presents a vision for an substantial expansion of the current IceCube detector, IceCube-Gen2, including the aim of instrumenting a 10km310\,\mathrm{km}^3 volume of clear glacial ice at the South Pole to deliver substantial increases in the astrophysical neutrino sample for all flavors. A detector of this size would have a rich physics program with the goal to resolve the sources of these astrophysical neutrinos, discover GZK neutrinos, and be a leading observatory in future multi-messenger astronomy programs

    Lateral distribution of muons in IceCube cosmic ray events

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    In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high p(T) (>2 GeV/c) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard p(T) component that can be described by perturbative quantum chromodynamics. However, the rates and the zenith angle distributions of these events are not well reproduced with the cosmic ray models tested here, even those that include charm interactions. This discrepancy may be explained by a larger fraction of kaons and charmed particles than is currently incorporated in the simulations.R. Abbasi ... G. C. Hill ... et al. (IceCube Collaboration

    A novel capsule-based smell test fabricated via coaxial dripping

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    In this paper, we demonstrate that aromatic oil capsules, produced by dripping droplets, can offer a simple, yet effective, testing tool to aid in the diagnosis of various diseases, in which the loss of smell is a key symptom. These include chronic neurological conditions such as Parkinson's and Alzheimer's diseases, and acute respiratory infections such as that caused by COVID-19. The capsules were fabricated by concentrically dripping oil/alginate droplets, from a coaxial nozzle, into an oppositely charged ionic liquid. This fabrication technique enables full control over the capsule size, the shell thickness and the volume of the encapsulated oil. After formation, liquid capsules were left to dry and form a solid crust surrounding the oil. The prototype test consists of placing a standardized number of capsules between adhesive strips that users crush and pull apart to release the smell. In addition to the fabrication method, a simple mathematical model was developed to predict the volume of encapsulated oil within the capsule in terms of the flow rate ratio and the nozzle size. Tensile tests show that capsule strength is inversely proportional to its size owing to an increase in the shell thickness. By increasing the alginate concentration, the load required to rupture the capsule increases, to the point where capsules are too stiff to be broken by a fingertip grip. Results from a preliminary screening test, within a group of patients with Parkinson's disease, found that smells were detectable using a ‘forced choice’ paradigm

    Revitalization of Education for Children in Indonesian Families During the Covid-19 Pandemic

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    In Indonesia, three institutions are responsible for the sustainability of education, namely family, school, and society. Since a child enters school age, the responsibility for his/her education is left to the school, without eliminating his/her family. During the Covid-19 pandemic, it seems as if the role of education is left to the family, which is forced to accept and support the government’s efforts. This article would examine literature and opinions regarding strengthening the role of education in the family during the Covid-19 pandemic. The purpose was to find out what the role of the family is in the educational process of children at home during the Covid-19 pandemic as a form of harmonious cooperation with schools and what families should do to strengthen education during the Covid-19 pandemic. The study found that the role of the family to strengthen education at home was to motivate, guide, and assist children in participating in learning at home, realize their obligations and responsibility for education for their children, and support all directions from the government, schools, and teachers regarding the learning process at home
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