251 research outputs found

    Numerical Computations of Radial Vibrations of Axially Polarized Piezoelectric Circular Cylinder

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    Influence of the initial stresses on the frequency equation and the natural frequencies for radial vibrations of axially polarized piezoelectric circular cylinder have been taken into account. The mechanical boundary conditions correspond to those of stress free lateral surfaces while the electrical boundary conditions correspond to those of open and short circuit are considered. The satisfaction of the boundary conditions lead to the frequency equation, in the form of determinant involving Bessel functions, have been taken into consideration. The roots of the frequency equations give the values of the characteristic circular frequency parameters of the first three modes for various geometries. These roots are numerically computed and programmed for numerical evaluation by ''Bisection Method Iterations Technique (BMIT)'' and presented graphically for various thickness of the circular cylinder and for different values of the initial stress. The effect of the initial stress on the natural frequencies are illustrated graphically for a transversely isotropic piezoelectric martial PZT?4 circular cylinder. It is found that both the thickness of the circular cylinder and the initial stress have a substantial effect on the dispersion behavior. The results obtained in this paper may be applied to the vibrations of annular accelerometers operating in the radial shear mode. Also, they have theoretical basis application and have meaningful design for piezoelectric probes and electro-acoustic devices in the nondestructive evaluation. Keywords: Piezoelectricity, frequency equation, Transverse surface waves, Initial stress, Hexagonal crystals

    Annotated corpus of mesopotamian-iraqi dialect for sentiment analysis in social media

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    Research on Sentiment Analysis in social media by using Mesopotamian-Iraqi Dialect (MID) of Arabic language was rarely found, there is no reliable dataset developed in MID neither an annotated corpus for the sentiment analysis of social media in this dialect. Therefore, this gap was the main stumbling block for researchers of sentiment analysis in MID, for this reason, this paper introduced the development of an annotated corpus of Mesopotamian-Iraqi Dialect for sentiment analysis in social media and named it as (ACMID) stands for (the annotated corpus of Mesopotamian-Iraqi Dialect) to help researchers in future for using this corpus for their studies, to the best of our knowledge this is the first annotated corpus that both classify polarity as well as emotion classification in MID. Likewise, Facebook as the most popular social platform among Iraqis was used to extract the data from its popular Iraqi pages. 5000 comments were extracted from these pages classified by its polarity (Positive, Negative, Neutral, Spam) by two Iraqi annotators, these annotators were simultaneously classifying the same comments according to Ekman seven universal emotions (Anger, Fear, Disgust, Happiness, Sadness, Surprise, Contempt) or no emotion. Cohen’s kappa coefficient was then used to compare the two annotators’ results to find the reliability of these results. The data shows a comparable value among the two annotators for the polarity classification as high as 0.82, while for the emotion classification the result was 0.65

    UV/Vis+ Photochemistry Database : Structure, Content and Applications

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    Acknowledgments This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. However, the authors are indebted to those colleagues who support us in maintaining the database through the provision of spectral and other photochemical data and information. The National Center for Atmospheric Research is operated by the University Coporation for Atmopsheric Research, under the sponsorship of the National Science Foundation. Disclaimer: The views expressed in this paper are those of the authors and do not necessarily represent the views or policies of the U.S.EPA. Mention of trade names or products does not convey and should not be interpreted as conveying official U.S. EPA approval, endorsement, or recommendation.Peer reviewedPublisher PD

    Internet-based search of randomised trials relevant to mental health originating in the Arab world

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    BACKGROUND: The internet is becoming a widely used source of accessing medical research through various on-line databases. This instant access to information is of benefit to busy clinicians and service users around the world. The population of the Arab World is comparable to that of the United States, yet it is widely believed to have a greatly contrasting output of randomised controlled trials related to mental health. This study was designed to investigate the existence of such research in the Arab World and also to investigate the availability of this research on-line. METHODS: Survey of findings from three internet-based potential sources of randomised trials originating from the Arab world and relevant to mental health care. RESULTS: A manual search of an Arabic online current contents service identified 3 studies, MEDLINE, EMBASE, and PsycINFO searches identified only 1 study, and a manual search of a specifically indexed, study-based mental health database, PsiTri, revealed 27 trials. CONCLUSION: There genuinely seem to be few trials from the Arab world and accessing these on-line was problematic. Replication of some studies that guide psychiatric/psychological practice in the Arab world would seem prudent

    GRFS and CRFS in alternative donor hematopoietic cell transplantation for pediatric patients with acute leukemia.

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    We report graft-versus-host disease (GVHD)-free relapse-free survival (GRFS) (a composite end point of survival without grade III-IV acute GVHD [aGVHD], systemic therapy-requiring chronic GVHD [cGVHD], or relapse) and cGVHD-free relapse-free survival (CRFS) among pediatric patients with acute leukemia (n = 1613) who underwent transplantation with 1 antigen-mismatched (7/8) bone marrow (BM; n = 172) or umbilical cord blood (UCB; n = 1441). Multivariate analysis was performed using Cox proportional hazards models. To account for multiple testing, P \u3c .01 for the donor/graft variable was considered statistically significant. Clinical characteristics were similar between UCB and 7/8 BM recipients, because most had acute lymphoblastic leukemia (62%), 64% received total body irradiation-based conditioning, and 60% received anti-thymocyte globulin or alemtuzumab. Methotrexate-based GVHD prophylaxis was more common with 7/8 BM (79%) than with UCB (15%), in which mycophenolate mofetil was commonly used. The univariate estimates of GRFS and CRFS were 22% (95% confidence interval [CI], 16-29) and 27% (95% CI, 20-34), respectively, with 7/8 BM and 33% (95% CI, 31-36) and 38% (95% CI, 35-40), respectively, with UCB (P \u3c .001). In multivariate analysis, 7/8 BM vs UCB had similar GRFS (hazard ratio [HR], 1.12; 95% CI, 0.87-1.45; P = .39), CRFS (HR, 1.06; 95% CI, 0.82-1.38; P = .66), overall survival (HR, 1.07; 95% CI, 0.80-1.44; P = .66), and relapse (HR, 1.44; 95% CI, 1.03-2.02; P = .03). However, the 7/8 BM group had a significantly higher risk for grade III-IV aGVHD (HR, 1.70; 95% CI, 1.16-2.48; P = .006) compared with the UCB group. UCB and 7/8 BM groups had similar outcomes, as measured by GRFS and CRFS. However, given the higher risk for grade III-IV aGVHD, UCB might be preferred for patients lacking matched donors. © 2019 American Society of Hematology. All rights reserved
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