Abstract: This work concerns the transient response in elastodynamic quarter plane problems with mixed boundary conditions. Two dimensional elastodynamic equations are solved analytically applying of integral transformations and Cagniard-de Hoop method and complex integration. The plots of stresses in response to step function are obtained by numerical integration.

Recently, it has been observed that a new method for generating continuous distributions, T 􀀀 X family, can be quite effectively used to analyze the data in one dimension. The aim of this study is to generalize this method to two dimensional space so that the marginals would have T 􀀀 X distributions. So, several examples and properties of this family have been presented. As an application, a special distribution of this family, called bivariate Weibull-Rayleigh-Rayleigh, is fitted to a data set and is shown to have a better fit.

The taxonomy, morphology and distribution of rust species on Arundineae (Poaceae) in Iran was studied. Five species of Puccinia viz. P. magnusiana Korn., P. phragmitis (Schumach.)Korn., P. isiacae G. Winter, P. trabutii Roum. & Sacc. and P. akiyoshidanensis Morim. are described and illustrated. Of these, Puccinia akiyoshidanensis is considered as a distinct species and newly recorded for Iranian rust flora. Moreover, on the basis of examination of type and authentic materials, P. isiacae, P. trabutii, P. moriokaensis S. Ito and P. okatamaensis S. Ito are considered as distinct species. A distribution map and key to the identified Puccinia species on Arundineae in Iran is also given.

Background/Objective: Thyroid nodules are a common finding, especially in our country. In this study, we evaluated the role of conventional ultrasonography (US) and color doppler sonography (CDS) in assessment of cold thyroid nodules. Materials and Methods: Ninety-seven patients with a cold thyroid nodule were examined by US and CDS before thyroidectomy .On US, the presence of a halo sign, hypoechogenicity or microcalcification was evaluated .The vascular pattern on CDS was classified as follows: Type 1, absence of blood flow; Type 2, perinodular blood flow; Type 3, intranodular blood flow. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy of ultrasound and color doppler findings were evaluated. Ultrasound findings have been compared with postoperative pathological result. Results: In 38 patients, thyroidal carcinoma was found. Absence of halo sign, presence of microcalcification and hypoechogenicity were predictive of malignancy (P < 0.001). Presence of intranodular hyper-vascularity and perinodular hypervascularity were in favor of malignancy (P < 0.001) and benignity (P < 0.01), respectively. An avascular pattern could not differentiate between benign and malignant nodules. Conclusion: US and CDS findings can predict malignant nodules, especially when multiple signs are simultaneously present.

In this paper we propose a zero-inflated version of the extended alternative hyper-Poisson distribution of Kumar and Nair (2013b) and investigate some of its important properties and applications. We derive expressions for its probability generating function, mean, variance, etc. along with recursion formulae for probabilities, raw moments and factorial moments. The estimation of the parameters of the distribution is also attempted and it has been fitted to certain real life data sets for highlighting its practical relevance. Further, generalized likelihood ratio test procedure is applied for examining the significance of the parameters of the model and a simulation study is conducted for assessing the performance of the maximum likelihood estimators of the parameters of the distribution.