30 research outputs found

    Probabilistic Power Distribution Planning Using Multi-Objective Harmony Search Algorithm

    Get PDF
    In this paper, power distribution planning (PDP) considering distributed generators (DGs) is investigated as a dynamic multi-objective optimization problem. Moreover, Monte Carlo simulation (MCS) is applied to handle the uncertainty in electricity price and load demand. In the proposed model, investment and operation costs, losses and purchased power from the main grid are incorporated in the first objective function, while pollution emission due to DGs and the grid is considered in the second objective function. One of the important advantages of the proposed objective function is a feeder and substation expansion in addition to an optimal placement of DGs. The resulted model is a mixed-integer non-linear one, which is solved using a non-dominated sorting improved harmony search algorithm (NSIHSA). As multi-objective optimization problems do not have a unique solution, to obtain the final optimum solution, fuzzy decision making analysis tagged with planner criteria is applied. To show the effectiveness of the proposed model and its solution, it is applied to a 9-node distribution system

    Preoperative assessment of meningioma aggressiveness by Thallium-201 brain SPECT

    Get PDF
    Introduction: Meningioma is usually a benign brain tumor, but sometimes with aggressive course. The aim of this study was to assess the ability of 201Tl Brain SPECT to differentiate the pathologic grade of meningioma preoperatively. Methods: Thirty lesions in 28 patients were evaluated in this study. Early (20 minutes) and late (3 hours) brain SPECT images were performed and early uptake ratio (EUR), late uptake ratio (LUR) and retention index (RI) were calculated. All patients were operated and pathologic grade of tumors were defined according to World Health Organization grading system. Results: SPECT results were compared in different pathologic groups. Data analysis clarified no significant difference of EUR in benign and aggressive meningioma (P=0.2). However LUR and RI were significantly higher in aggressive tumors (P=0.001 and P=0.02, respectively). Conclusion: According to our data Tl-201 Brain SPECT with early and late imaging has 80 sensitivity and specificity to differentiate malignant from benign meningioma

    Impact of metoclopramide on image quality in myocardial perfusion imaging

    Get PDF
    Background: The effectiveness of metoclopramide in reducing gastrointestinal-induced artifacts in myocardial perfusion imaging (MPI) is a subject of debate. We examined the significance of this pharmacological intervention in the quality of images obtained from MPI studies. Patients and Methods: A total of 211 suspected or known cases with coronary artery disease routinely referred to our nuclear medicine department for MPI were randomly assigned to group A and group B. Group A (N=125) comprised patients who received 10 mg of metoclopramide orally after the injection of the radiotracer technetium-99m-labeled methoxyisobutyl isonitril (Tc-MIBI) 1 h before image acquisition, and group B (N=86) comprised patients who did not receive any pharmacological intervention and were considered the control group. All the scans in each group were assessed in the rest phase of a routine 2-day protocol. The single-photon emission computerized tomography (SPECT) images were visually evaluated in terms of extracardiac activities and their effects on image quality by three nuclear medicine physicians, who were blinded to the details of the protocol. Results: Of the 125 patients who had received metoclopramide, 16 (13%) had nonacceptable, 72 (57.6%) had acceptable (interpretable), and 37 (29.6%) had good image quality. The image quality in group B was nonacceptable in 10 (11.23%), acceptable in 48 (50.23%), and good in 28 (33.56%) patients. The overall interobserver agreement was good (κ: 0.6-0.9, P<0.05) among the three readers. Conclusion: There was no statistically significant difference in terms of MPI-SPECT image quality between patients who received metoclopramide and those in the control group. Metoclopramide, therefore, did not exert a remarkable effect on the quality of our MPI scans. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

    Assessment of left ventricular mechanical dyssynchrony by phase analysis of gated-SPECT myocardial perfusion imaging and tissue Doppler imaging: Comparison between QGS and ECTb software packages

    Get PDF
    Background: Recently, the phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has become feasible via several software packages for the evaluation of left ventricular mechanical dyssynchrony. We compared two quantitative software packages, quantitative gated SPECT (QGS) and Emory cardiac toolbox (ECTb), with tissue Doppler imaging (TDI) as the conventional method for the evaluation of left ventricular mechanical dyssynchrony. Methods and Results: Thirty-one patients with severe heart failure (ejection fraction ≤35%) and regular heart rhythm, who referred for gated-SPECT MPI, were enrolled. TDI was performed within 3 days after MPI. Dyssynchrony parameters derived from gated-SPECT MPI were analyzed by QGS and ECTb and were compared with the Yu index and septal-lateral wall delay measured by TDI. QGS and ECTb showed a good correlation for assessment of phase histogram bandwidth (PHB) and phase standard deviation (PSD) (r = 0.664 and r = 0.731, P < .001, respectively). However, the mean value of PHB and PSD by ECTb was significantly higher than that of QGS. No significant correlation was found between ECTb and QGS and the Yu index. Nevertheless, PHB, PSD, and entropy derived from QGS revealed a significant (r = 0.424, r = 0.478, r = 0.543, respectively; P < .02) correlation with septal-lateral wall delay. Conclusion: Despite a good correlation between QGS and ECTb software packages, different normal cut-off values of PSD and PHB should be defined for each software package. There was only a modest correlation between phase analysis of gated-SPECT MPI and TDI data, especially in the population of heart failure patients with both narrow and wide QRS complex. © 2014, American Society of Nuclear Cardiology

    Metaheuristics for Transmission Network Expansion Planning

    Get PDF
    This chapter presents the characteristics of the metaheuristic algorithms used to solve the transmission network expansion planning (TNEP) problem. The algorithms used to handle single or multiple objectives are discussed on the basis of selected literature contributions. Besides the main objective given by the costs of the transmission system infrastructure, various other objectives are taken into account, representing generation, demand, reliability and environmental aspects. In the single-objective case, many metaheuristics have been proposed, in general without making strong comparisons with other solution methods and without providing superior results with respect to classical mathematical programming. In the multi-objective case, there is a better convenience of using metaheuristics able to handle conflicting objectives, in particular with a Pareto front-based approach. In all cases, improvements are still expected in the definition of benchmark functions, benchmark networks and robust comparison criteria

    Molecular characterization of a novel ssRNA ourmia-like virus from the rice blast fungus Magnaporthe oryzae

    Get PDF
    In this study we characterize a novel positive and single stranded RNA (ssRNA) mycovirus isolated from the rice field isolate of Magnaporthe oryzae Guy11. The ssRNA contains a single open reading frame (ORF) of 2,373 nucleotides in length and encodes an RNA-dependent RNA polymerase (RdRp) closely related to ourmiaviruses (plant viruses) and ourmia-like mycoviruses. Accordingly, we name this virus Magnaporthe oryzae ourmia-like virus 1 (MOLV1). Although phylogenetic analysis suggests that MOLV1 is closely related to ourmia and ourmia-like viruses, it has some features never reported before within the Ourmiavirus genus. 3' RLM-RACE (RNA ligase-mediated rapid amplification of cDNA ends) and extension poly(A) tests (ePAT) suggest that the MOLV1 genome contains a poly(A) tail whereas the three cytosine and the three guanine residues present in 5' and 3' untranslated regions (UTRs) of ourmia viruses are not observed in the MOLV1 sequence. The discovery of this novel viral genome supports the hypothesis that plant pathogenic fungi may have acquired this type of viruses from their host plants

    The Effect of Sustained Teacher Feedback on CAF, Content and Organization in EFL Writing

    Get PDF
    Despite teachers' mainstream practices in L2 writing classrooms addressing different dimensions of writing over time, much of the research on feedback in recent years has been of relative short duration and has mainly focused on accuracy. The current longitudinal study investigated the influence of sustained teacher written feedback on accuracy, syntactic complexity, fluency, content, and organization in an EFL context. Ninety-two learners were divided into four groups, receiving written corrective feedback, feedback on content and organization, multilateral feedback (i.e., on grammatical accuracy, content, and organization), and no feedback over a 3½-month period. They completed a pre-test, post-test, and delayed post-test and wrote and revised eight interim expository compositions on a weekly basis. Results showed that the three treatment groups significantly improved in the dimensions on which they received feedback. However, only the groups who received feedback on content and organization improved in fluency. Importantly, the multilateral group improved in accuracy as well as fluency, content and organization. Theoretically, the findings endorse the language learning potentials of sustained writing as long as it is guided by teacher feedback. The findings provide empirical support for the influence of sustained feedback on expanding and consolidating learners’ explicit knowledge of L2 writing

    Estimating the soil water retention curve - comparison of multiple nonlinear regression approach and random forest data mining technique

    No full text
    This study evaluates the performance of the random forest (RF) method on the prediction of the soil water retention curve (SWRC) and compares its performance with those of nonlinear regression (NLR) and Rosetta-based pedotransfer functions (PTFs), which has not been reported so far. Fifteen RF and NLR-based PTFs were constructed using readily-available soil properties for 223 soil samples from Iran. The general performance of RF and NLR-based PTFs was quantified by the integral root mean square error (IRMSE), Akaike’s information criterion (AIC) and coefficient of determination (R2). The results showed that the accuracy of the RF-based PTFs was significantly (P<0.05) better than the NLR-based PTFs, and that the reliability of the NLR-based PTFs was significantly (P<0.01) better than the RF-based PTFs and all of the Rosetta-based PTFs. The average values of the IRMSE, AIC and R2 of the RF method were 0.041 cm3 cm-3, -16997.7, and 0.987, and 0.053 cm3 cm-3, -15547.5, and 0.981 for the training and testing steps of all PTFs, respectively, whereas the values for the NLR method were 0.046 cm3 cm-3, -16616.4, and 0.984, and 0.048 cm3 cm-3, -16355.6, and 0.983 for the training and testing steps, respectively. The PTF5 of the RF and NLR methods, with inputs of sand and clay contents, bulk density, and the water content at field capacity and permanent wilting point, had the greatest R2 values (0.987 and 0.989, respectively), and the lowest IRMSE values (0.039 and 0.032 cm3 cm-3, respectively) compared to other PTFs for the testing step. Overall, the RF method had less reliability for the prediction of the SWRC compared to the NLR method due to overprediction, uncertainty of determination of forest scale and instability in the testing step. These findings could provide the scientific basis for further research on the RF method

    Development of a robust DNA damage model including persistent telomere-associated damage with application to secondary cancer risk assessment

    No full text
    Mathematical modelling has been instrumental to understand kinetics of radiation-induced DNA damage repair and associated secondary cancer risk. The widely accepted two-lesion kinetic (TLK) model assumes two kinds of double strand breaks, simple and complex ones, with different repair rates. Recently, persistent DNA damage associated with telomeres was reported as a new kind of DNA damage. We therefore extended existing versions of the TLK model by new categories of DNA damage and re-evaluated those models using extensive data. We subjected different versions of the TLK model to a rigorous model discrimination approach. This enabled us to robustly select a best approximating parsimonious model that can both recapitulate and predict transient and persistent DNA damage after ionizing radiation. Models and data argue for i) nonlinear dose-damage relationships, and ii) negligible saturation of repair kinetics even for high doses. Additionally, we show that simulated radiation-induced persistent telomere-associated DNA damage foci (TAF) can be used to predict excess relative risk (ERR) of developing secondary leukemia after fractionated radiotherapy. We suggest that TAF may serve as an additional measure to predict cancer risk after radiotherapy using high dose rates. This may improve predicting risk-dose dependency of ionizing radiation especially for long-term therapies
    corecore