259 research outputs found

    A GaAs-based self-aligned stripe distributed feedback laser

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    We demonstrate operation of a GaAs-based self-aligned stripe (SAS) distributed feedback (DFB) laser. In this structure, a first order GaInP/GaAs index-coupled DFB grating is built within the p-doped AlGaAs layer between the active region and the n-doped GaInP opto-electronic confinement layer of a SAS laser structure. In this process no Al-containing layers are exposed to atmosphere prior to overgrowth. The use of AlGaAs cladding affords the luxury of full flexibility in upper cladding design, which proved necessary due to limitations imposed by the grating infill and overgrowth with the GaInP current block layer. Resultant devices exhibit single-mode lasing with high side-mode-suppression of >40 dB over the temperature range 20 °C–70 °C. The experimentally determined optical profile and grating confinement correlate well with those simulated using Fimmwave

    Isolation of rapid growing mycobacteria from soil and water in Iran

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    A total of 350 soil samples were collected from different part of Uremia city and suburbs. We used 3% sodium lauryl sulfate and 1% NaOH for decontamination of soil samples. Of 350 samples, mycobacteria were isolated from 65 (18.3%) specimens. Mycobacterium fortuitum with 18(5.14) strains yielded the highest frequency of isolation. The other isolates were: Mycobacterium peregrinum 11(3.14%), Mycobacterium flvescens 10 (2.85%), Mycobacterium chelonae 6 (1.71%), Mycobacterium mucogenicum 6(1.71%), Mycobacterium thermoresistable 4(1.14%), Mycobacterium abscessus 3 (0.85%), Mycobacterium neoaurum 2(0.57%), Mycobacterium smegmatis 2 (0.57%) and M. fortuitum third biovalant complex 3 (0.85%). The mean pH of soil was 7.89 ± 0.379 (max 8.5, min 7.5). Our data showed an abundant occurrence of mycobacteria in low pH (P value = 0001). We also collected 120 water samples from rivers, brooks and drinking water. Water samples decontaminated were by adding cetylpyridinium chloride (CPC) to give final concentration of 0.05%. Mycobacteria isolated from 12 water samples. The predominant isolated species were M. fortuitum and Mycobacterium cheloni. The majorityisolates were from brooks and surface waters

    Iron Status in Febrile Seizure: A Case-Control Study

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    ObjectiveData on the relationship between iron deficiency anemia and febrile convulsions are controversial. The aim of this study was to determine the association between iron deficiency anemia and febrile convulsions among children.Materials & MethodsThis case-control study was conducted during 2006-2007, on 90 children with febrile seizures (case) and 90 febrile children without seizures (control) referred to the Amirkola children hospital (a referral hospital in the north of Iran). Two groups were matched for age and sex. In all children hemoglobin (Hb) level, hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and plasma ferritin (PF) were determined and the data collected were analyzed statistically using the t-test.ResultsThe mean PF and TIBC levels were not significantly different in the febrile seizure compared to the reference group; neither were differences in Hb levels statistically significant between two groups. However MCV and MCH were significantly higher in the febrile seizure group (pConclusionPlasma ferritin levels were not significantly lower in children with febrile seizures in comparison with the children in control group. It seems that iron insufficiency does not play a role in pediatric febrile seizures.

    Higher-order approximation of cubic–quintic duffing model

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    We apply an Artificial Parameter Lindstedt-Poincaré Method (APL-PM) to find improved approximate solutions for strongly nonlinear Duffing oscillators with cubic–quintic nonlinear restoring force. This approach yields simple linear algebraic equations instead of nonlinear algebraic equations without analytical solution which makes it a unique solution. It is demonstrated that this method works very well for the whole range of parameters in the case of the cubic-quintic oscillator, and excellent agreement of the approximate frequencies with the exact one has been observed and discussed. Moreover, it is not limited to the small parameter such as in the classical perturbation method. Interestingly, This study revealed that the relative error percentage in the second-order approximate analytical period is less than 0.042% for the whole parameter values. In addition, we compared this analytical solution with the Newton– Harmonic Balancing Approach. Results indicate that this technique is very effective and convenient for solving conservative truly nonlinear oscillatory systems. Utter simplicity of the solution procedure confirms that this method can be easily extended to other kinds of nonlinear evolution equations

    Clinical presentation of coronary arteriovenous fistula according to age and anatomic orientation

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    Background: Coronary arteriovenous fistulas (CAVFs) are direct connections from one or more coronary arteries to cardiac chambers or a large vessel. They are mostly of congenital origin. The aim of this study was to describe clinical presentation and also delineate the course and management of CAVF. Methods: Clinical data, chest x-rays, echocardiographic and angiographic evaluation of 40 patients with congenital CAVF during 1990 to 2008 were reviewed retrospectively. Results: Seventeen patients were �20 years old (42.5) were mostly asymptomatic, and twenty tree cases were older than 20 years old (57.5), mostly symptomatic (P < 0.05). Twenty one (52.5) patients had pure CAVF and nineteen (47.5) patients with associated intarcardiac congenital heart disease (15) or acquired valvular and coronary arteries diseases (32.5). CAVFs mostly originated from left anterior descending artery (LAD) (42.5) and mostly drained into the main pulmonary artery (MPA) (35 ). Twenty-four patients underwent CAVF surgical ligation. From twenty-one patients with pure CAVF, eight (38) patients were complicated by congestive heart failure and aneurism formation of fistula. Conclusion: Unlike some previous reports, in our study, the most prevalent origin site for CAVFs was the left anterior descending (LAD). Most patients with CAVFs especially those who went first diagnosed before 20 years old were asymptomatic. On the other hand, as the continuous murmur is not always detected in children or infants, consequently, cases of spontaneous closure may remain undetected. All symptomatic and asymptomatic patients with moderate to severe shunting should be operated on and minimal morbidity and good surgical results could be expected

    Accelerated Real-Time Simulations for Testing a Reactive Power Flow Controller in Long-Term Case Studies

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    This paper presents the development of an accelerated real-time cosimulation and testing platform, especially for long-term simulations of power systems. The platform is planned to be utilized in the development and testing of active network management functions for microgrids and smart grids. Long-term simulations are needed in order to study, for example, the potential weekly, monthly, or yearly usage of distribution-network-connected distributed energy resources for different technical flexibility services. In order to test new algorithms in long-term study cases, real-time simulations or hardware-in-the-loop tests should be accelerated. This paper analyzes the possibilities and challenges of accelerated long-term simulations in studying the potential use of a large-scale wind turbine for reactive power flow control between distribution system operator (DSO) and transmission system operator (TSO) networks. To this end, the reactive power flow control is studied for different voltage levels (HV and MV) in the Sundom Smart Grid in Vaasa, Finland. The control of reactive power flow between HV and MV networks is realized with a reactive power window control algorithm for a 3.6 MW MV-network-connected wind turbine with a full-scale power converter. The behaviour of the reactive power controller during long-term simulations is studied by offline and real-time simulations. Moreover, the real-time simulations are performed with both software-in-the-loop and controller-hardware-in-the-loop.Copyright © 2020 Katja H. Sirviö et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.fi=vertaisarvioitu|en=peerReviewed

    Isotherm and Kinetic Studies on Adsorption of Pb, Zn and Cu by Kaolinite

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    The feasibility of kaolinite used as a low-cost adsorbent for the removal of Pb(II), Zn(II) and Cu(II) from aqueous solutions was investigated. During the removal process, batch technique was used, and the effects of heavy metal concentration and contact time on adsorption efficiency at pH of 4.5, under a constant temperature of 20±1 °C were studied. The experimental results were analyzed using four adsorption isotherm models; Freundlich, Langmuir, Temkin and Redlich-Peterson. Evaluating the correlation coefficients showed that the Redlich-Peterson isotherm described the data appropriable than others. The adsorption capacities (qm) from the Langmuir isotherm for Pb(II), Zn(II) and Cu(II) are found as 7.75 mg/g, 4.95 mg/g and 4.42 mg/g respectively. The effectiveness of kaolinite in the sorption of the three metals from aqueous system was Pb(II) > Zn(II) > Cu(II). Kinetic studies showed that a pseudosecond order model was more suitable than the pseudo first order model. It is concluded that kaolinite can be used as an effective adsorbent for removing Pb(II), Zn(II) and Cu(II) from aqueous solutions

    Higher-order approximation of cubic–quintic duffing model

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    We apply an Artificial Parameter Lindstedt-Poincaré Method (APL-PM) to find improved approximate solutions for strongly nonlinear Duffing oscillators with cubic–quintic nonlinear restoring force. This approach yields simple linear algebraic equations instead of nonlinear algebraic equations without analytical solution which makes it a unique solution. It is demonstrated that this method works very well for the whole range of parameters in the case of the cubic-quintic oscillator, and excellent agreement of the approximate frequencies with the exact one has been observed and discussed. Moreover, it is not limited to the small parameter such as in the classical perturbation method. Interestingly, This study revealed that the relative error percentage in the second-order approximate analytical period is less than 0.042% for the whole parameter values. In addition, we compared this analytical solution with the Newton– Harmonic Balancing Approach. Results indicate that this technique is very effective and convenient for solving conservative truly nonlinear oscillatory systems. Utter simplicity of the solution procedure confirms that this method can be easily extended to other kinds of nonlinear evolution equations

    Impact of health literacy and self-care behaviors on health-related quality of life in Iranians with type 2 diabetes: a cross-sectional study

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    Background: Regarding the importance of health literacy as a key factor in self-care, appropriate understanding of health information by patients with type 2 diabetes mellitus (T2DM) is fundamental for better management of risk factors, which can also benefit their quality of life. This study aimed to describe the relationship between health literacy (HL), and self-care behaviors with health-related quality of life (HRQL) in patients with T2DM. Methods: A cross-sectional survey was done in Iran in 2019. Patients were recruited randomly from health centers by medical records (n = 192, 55.2 male, mean age 58.12 years). The data collection included demographic form, health literacy questionnaire, diabetes self-care behavior questionnaire, and world health organization�s Quality of Life-BREF (WHOQOL-BREF). Analyses were adjusted for confounders using hierarchical regression analysis. Results: HL as predictor variables explained 47.5 of variance in overall HRQL (p value < 0.001), reading health information was the strongest HL dimension (β = 0.478). Self-care behaviors explained an additional 13.6 of the HRQL variance. In total, 65.5 of the variation in the HRQL is explained by the HL, self-care behavior, and the demographic variables. Conclusion: We found that more almost two-third of the HRQL explained by the HL and self-care behaviors. Given the importance of health literacy and self-care behaviors in the quality of life in patients with T2DM, adoption of health-promoting behaviors and increasing health literacy can be beneficial for promoting quality of life among these patients. © 2020, The Author(s)
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