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The Zagros fold-thrust belt of Iran, as a continental-continental collision zone, is one of the most seismically active regions of the world. In this research, statistical point pattern analysis of earthquake locations in this region during 1976-2019 and the assessment of spatial association between earthquakes and major active faults of the region were carried out. For this purpose, different measures, (e.g., Nearest Neighbor Ratio, Global Moran's I and Local Getis-Ord's Gi* indices) were estimated and computed for the data catalog. Additionally, the directional anisotropy of the earthquake epicenters distribution and earthquake-fault association were assessed. Results obtained indicate a completely clustered pattern of epicenters for the whole region and also indicate that earthquakes with greater magnitudes show higher degrees of clustering. Also, a spatial autocorrelation of higher values of magnitudes are observed. The spatial relationships of earthquake locations and active faults pattern indicates that the trend of maximum dispersion of epicenters for the whole region is remarkably parallel with the general trend of this belt, as well as with the dominant trend of the major active faults of the region. Moreover, toward the south of the region, an obvious change in the directional anisotropy of epicenters is observed. The results of this study indicate that spatial analysis techniques reliably could be employed for revealing the seismicity pattern in tectonically active regions. [ABSTRACT FROM AUTHOR]

The problem of computing the diameter of a set of points on a dataset is one of the fundamental issues in computational geometry, which is used in many applications. Since precisely computing the diameter has required quadratic time, some approximation approaches to this problem is considered. In this paper, we propose a new (1 + O(ε))-approximation algorithm with O(n+1/ε(d-1)/2) running time for computing the diameter of a set of n points in the d-dimensional Euclidean space for a fixed dimension d, where 0 < ε ⩽ 1. This result provides some improvements in the running time of this problem in comparison with previous algorithms. Index Terms--Computational geometry, approximation algorithms, diameter, point-set, fixed dimensions. [ABSTRACT FROM AUTHOR]

In this study, the waiting time, spatial distance, and migrating trend pattern of successive large earthquakes in Iran have been investigated. In order to carry out this work, the earthquake data of Iran with M ³ 4.5 (1976-2018) have been obtained from the USGS catalog. Then, the statistical distribution of the Interevent time, migrating distance, and directional trend of migration of successive events were studied using different lower magnitude thresholds. The statistical and probability distributions of inter-event times of earthquakes were assessed and modelled by different distribution models. Furthermore, the directional analysis of migrating trends, as well as the spatial distances of successive events with different lower magnitude, was carried out. It is observed that the inter-event time distribution of earthquakes can be quite well fitted by the Gamma distribution model. The results obtained also indicate a decreasing trend in spatial distance distribution and a meaningful correlation between the directional pattern of the migrating trends of successive events and the dominant trends of the active faults of the region. The results of this study can be considered as an effective step to better understanding the temporal-spatial pattern of seismicity in Iran and also as an attempt to achieve earthquake prediction in this country, in a regional scale. [ABSTRACT FROM AUTHOR]

Background: Cardiac involvement, as one of the life-threatening manifestations of systemic sclerosis (SSc), is chiefly caused by collagen fiber deposition in the myocardium, which subsequently leads to conduction abnormalities. In the present study, we aimed to investigate the prevalence and clinical significance of bundle branch blocks (BBBs) and the fragmented QRS complex (fQRS) in Iranian patients with SSc. Methods: Forty-one patients with SSc were enrolled from the outpatient SSc clinic of Shariati Hospital, Tehran University of Medical Sciences, between October 2016 and February 2017. Twelve-lead ECG was obtained and interpreted for BBBs and the fQRS. To adjust for the confounding effects of non-SSc-related cardiovascular risk factors, we calculated the Framingham risk score to estimate the risk of cardiovascular diseases. The associations between the studied conduction abnormalities and SSc cutaneous subtypes; disease duration; and the Medsger SSc severity scale of cutaneous, pulmonary, and vascular involvements were also analyzed. Results: The study population consisted of 41 Iranian patients with SSc at a mean age of 47.48±11.57 years (82.9% female). The prevalence of BBBs and the fQRS was 26.8% and 36.6%, respectively. The fQRS was associated with the limited cutaneous SSc subtype (OR: 0.100, 95%CI: 0.018-0.553, and P=0.028). BBBs and the fQRS were not associated with either the Framingham risk score or the rest of the clinicodemographic variables. Conclusion: BBBs and the fQRS were more prevalent in our patients with SSc, without any association with the involvement of the other organs. These findings may suggest the independent pathophysiology of cardiac involvement in SSc.