2,434 research outputs found

    A note on the integrable discretization of the nonlinear Schr\"odinger equation

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    We revisit integrable discretizations for the nonlinear Schr\"odinger equation due to Ablowitz and Ladik. We demonstrate how their main drawback, the non-locality, can be overcome. Namely, we factorize the non-local difference scheme into the product of local ones. This must improve the performance of the scheme in the numerical computations dramatically. Using the equivalence of the Ablowitz--Ladik and the relativistic Toda hierarchies, we find the interpolating Hamiltonians for the local schemes and show how to solve them in terms of matrix factorizations.Comment: 24 pages, LaTeX, revised and extended versio

    Inappropriate use of antibiotics in the treatment of pharyngo-tonsilitis in children in Khartoum, Sudan

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    Background: Pharyngo-tonsillitis represents a major public health problem all over the world. Recent studies in Sudan have revealed alarming results reporting antibiotics over prescription in the management of acute tonsillitis.Objectives: The aim of this study was to estimate the prevalence of Group A Beta hemolytic streptococci and document the appropriateness of using antibiotics in the treatment of acute tonsillo-pharyngitis in Jaafar Ibn Auf Pediatrics Hospital.Materials and Methods: A cross sectional hospital based study was conducted in the period January to August 2012 in Jaafar Ibn Auf Hospital, the largest tertiary pediatrics hospital in Sudan. The sample size was 100 including children aged 2-17 years and got antibiotics treatment for their current sore throat. A pharyngeal swab was collected at presentation from tonsils and posterior pharynx. Gram staining was done first, and then Group A Beta hemolytic streptococci were isolated and identified in the laboratory by their growth characteristics. All children included in the study were assessed clinically and subjected to a structural questionnaire. Data were analyzed by SPSS version 19.Results: The estimated prevalence of Group A Beta hemolytic streptococci tonsillitis and/or pharyngitis was 22%, nevertheless the proportion of antibiotic prescription was 100%.Conclusion: Most children were treated inappropriately regarding the need for using antibiotics, the type of antibiotics used and the duration of management. As many studies suggested that increased using of antibiotics may be due to uncertainty of diagnosis, requesting scoring system or rapid diagnostic test can contribute to the reduction of the rate of antibiotics prescription.Keyword: Pharyngo-tonsillitis, inappropriate, children, antibiotics, Suda

    Does drug‐induced sleep endoscopy predict surgical success in transoral robotic multilevel surgery in obstructive sleep apnea?

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136419/1/lary26255_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136419/2/lary26255.pd

    Automatic quality control of cardiac MRI segmentation in large-scale population imaging

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    The trend towards large-scale studies including population imaging poses new challenges in terms of quality control (QC). This is a particular issue when automatic processing tools such as image segmentation methods are employed to derive quantitative measures or biomarkers for further analyses. Manual inspection and visual QC of each segmentation result is not feasible at large scale. However, it is important to be able to detect when an automatic method fails to avoid inclusion of wrong measurements into subsequent analyses which could otherwise lead to incorrect conclusions. To overcome this challenge, we explore an approach for predicting segmentation quality based on reverse classification accuracy, which enables us to discriminate between successful and failed cases. We validate this approach on a large cohort of cardiac MRI for which manual QC scores were available. Our results on 7,425 cases demonstrate the potential for fully automatic QC in the context of large-scale population imaging such as the UK Biobank Imaging Study

    Test of Replica Theory: Thermodynamics of 2D Model Systems with Quenched Disorder

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    We study the statistics of thermodynamic quantities in two related systems with quenched disorder: A (1+1)-dimensional planar lattice of elastic lines in a random potential and the 2-dimensional random bond dimer model. The first system is examined by a replica-symmetric Bethe ansatz (RBA) while the latter is studied numerically by a polynomial algorithm which circumvents slow glassy dynamics. We establish a mapping of the two models which allows for a detailed comparison of RBA predictions and simulations. Over a wide range of disorder strength, the effective lattice stiffness and cumulants of various thermodynamic quantities in both approaches are found to agree excellently. Our comparison provides, for the first time, a detailed quantitative confirmation of the replica approach and renders the planar line lattice a unique testing ground for concepts in random systems.Comment: 16 pages, 14 figure

    Comparative Analysis of Rankine Cycle Linear Fresnel Reflector and Solar Tower Plant Technologies: Techno-Economic Analysis for Ethiopia

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    The need to meet the world’s growing demand for energy in an environmentally sustainable manner has led to the exploration of various renewable energy (RE) resources for power gen-eration. The objective of this study is to examine the techno-economic potential of concentrated solar power plants (i.e., linear Fresnel reflector (LFR) and central receiver system (CRS) for electricity generation in Eastern African countries with a case study on Ethiopia. The study was conducted using the System Advisor Model (SAM). In order to estimate the economics of the two power plants, the Levelized cost of energy (LCOE) and the net present value (NPV) metrics were used. According to results obtained from the simulations, the LFR produced annual energy of 528 TWh at a capacity factor (CF) of 60.3%. The CRS also produced a total of 540 TWh at a CF of 61.9%. The LCOE (real) for the CRS is found to be 9.44 cent/kWh against 10.35 cent/kWh for the LFR. The NPV for both technologies is found to be positive for inflation rates of 2% and below. An inflation rate above 2% renders the two power plants financially impracticable. A real discount rate above 9% also renders both projects economically unviable. Based on the obtained results, the CRS system is identified as the best technology for electricity generation under the Jijiga climatic condition in Ethiopia. © 2022 by the authors. Li-censee MDPI, Basel, Switzerland.Taif University Researchers Supporting Project Number (TURSP-2020/61), Taif University, Taif, Saudi Arabia

    Micronutrient malnutrition and wasting in adults with pulmonary tuberculosis with and without HIV co-infection in Malawi

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    BACKGROUND: Wasting and micronutrient malnutrition have not been well characterized in adults with pulmonary tuberculosis. We hypothesized that micronutrient malnutrition is associated with wasting and higher plasma human immunodeficiency virus (HIV) load in adults with pulmonary tuberculosis. METHODS: In a cross-sectional study involving 579 HIV-positive and 222 HIV-negative adults with pulmonary tuberculosis in Zomba, Malawi, anthropometry, plasma HIV load and plasma micronutrient concentrations (retinol, α-tocopherol, carotenoids, zinc, and selenium) were measured. The risk of micronutrient deficiencies was examined at different severity levels of wasting. RESULTS: Body mass index (BMI), plasma retinol, carotenoid and selenium concentrations significantly decreased by increasing tertile of plasma HIV load. There were no significant differences in plasma micronutrient concentrations between HIV-negative individuals and HIV-positive individuals who were in the lowest tertile of plasma HIV load. Plasma vitamin A concentrations <0.70 μmol/L occurred in 61%, and zinc and selenium deficiency occurred in 85% and 87% respectively. Wasting, defined as BMI<18.5 was present in 59% of study participants and was independently associated with a higher risk of low carotenoids, and vitamin A and selenium deficiency. Severe wasting, defined as BMI<16.0 showed the strongest associations with deficiencies in vitamin A, selenium and plasma carotenoids. CONCLUSIONS: These data demonstrate that wasting and higher HIV load in pulmonary tuberculosis are associated with micronutrient malnutrition

    A practical approach to language complexity: a wikipedia case study

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    In this paper we present statistical analysis of English texts from Wikipedia. We try to address the issue of language complexity empirically by comparing the simple English Wikipedia (Simple) to comparable samples of the main English Wikipedia (Main). Simple is supposed to use a more simplified language with a limited vocabulary, and editors are explicitly requested to follow this guideline, yet in practice the vocabulary richness of both samples are at the same level. Detailed analysis of longer units (n-grams of words and part of speech tags) shows that the language of Simple is less complex than that of Main primarily due to the use of shorter sentences, as opposed to drastically simplified syntax or vocabulary. Comparing the two language varieties by the Gunning readability index supports this conclusion. We also report on the topical dependence of language complexity, that is, that the language is more advanced in conceptual articles compared to person-based (biographical) and object-based articles. Finally, we investigate the relation between conflict and language complexity by analyzing the content of the talk pages associated to controversial and peacefully developing articles, concluding that controversy has the effect of reducing language complexity

    A review of ECG-based diagnosis support systems for obstructive sleep apnea

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    Humans need sleep. It is important for physical and psychological recreation. During sleep our consciousness is suspended or least altered. Hence, our ability to avoid or react to disturbances is reduced. These disturbances can come from external sources or from disorders within the body. Obstructive Sleep Apnea (OSA) is such a disorder. It is caused by obstruction of the upper airways which causes periods where the breathing ceases. In many cases, periods of reduced breathing, known as hypopnea, precede OSA events. The medical background of OSA is well understood, but the traditional diagnosis is expensive, as it requires sophisticated measurements and human interpretation of potentially large amounts of physiological data. Electrocardiogram (ECG) measurements have the potential to reduce the cost of OSA diagnosis by simplifying the measurement process. On the down side, detecting OSA events based on ECG data is a complex task which requires highly skilled practitioners. Computer algorithms can help to detect the subtle signal changes which indicate the presence of a disorder. That approach has the following advantages: computers never tire, processing resources are economical and progress, in the form of better algorithms, can be easily disseminated as updates over the internet. Furthermore, Computer-Aided Diagnosis (CAD) reduces intra- and inter-observer variability. In this review, we adopt and support the position that computer based ECG signal interpretation is able to diagnose OSA with a high degree of accuracy
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