3-D Statistical Channel Model for Millimeter-Wave Outdoor Mobile Broadband Communications

This paper presents an omnidirectional spatial and temporal 3-dimensional statistical channel model for 28 GHz dense urban non-line of sight environments. The channel model is developed from 28 GHz ultrawideband propagation measurements obtained with a 400 megachips per second broadband sliding correlator channel sounder and highly directional, steerable horn antennas in New York City. A 3GPP-like statistical channel model that is easy to implement in software or hardware is developed from measured power delay profiles and a synthesized method for providing absolute propagation delays recovered from 3-D ray-tracing, as well as measured angle of departure and angle of arrival power spectra. The extracted statistics are used to implement a MATLAB-based statistical simulator that generates 3-D millimeter-wave temporal and spatial channel coefficients that reproduce realistic impulse responses of measured urban channels. The methods and model presented here can be used for millimeter-wave system-wide simulations, and air interface design and capacity analyses.Comment: 7 pages, 6 figures, ICC 2015 (London, UK, to appear

28 GHz and 73 GHz Millimeter-Wave Indoor Propagation Measurements and Path Loss Models

This paper presents 28 GHz and 73 GHz millimeter- wave propagation measurements performed in a typical office environment using a 400 Megachip-per-second broadband sliding correlator channel sounder and highly directional steerable 15 dBi (30 degrees beamwidth) and 20 dBi (15 degrees beamwidth) horn antennas. Power delay profiles were acquired for 48 transmitter-receiver location combinations over distances ranging from 3.9 m to 45.9 m with maximum transmit powers of 24 dBm and 12.3 dBm at 28 GHz and 73 GHz, respectively. Directional and omnidirectional path loss models and RMS delay spread statistics are presented for line-of-sight and non-line-of-sight environments for both co- and cross-polarized antenna configurations. The LOS omnidirectional path loss exponents were 1.1 and 1.3 at 28 GHz and 73 GHz, and 2.7 and 3.2 in NLOS at 28 GHz and 73 GHz, respectively, for vertically-polarized antennas. The mean directional RMS delay spreads were 18.4 ns and 13.3 ns, with maximum values of 193 ns and 288 ns at 28 GHz and 73 GHz, respectively.Comment: 7 pages, 9 figures, 2015 IEEE International Conference on Communications (ICC), ICC Workshop

Association between lumbar modic changes and MRI finding of degenerative disc in patients with low back pain

Background: Recent studies have indicated the relation of vertebral endplate lesions (Modic changes) to low back pain (LBP). The aim of this study was to investigate the Modic changes in magnetic resonance imaging (MRI) of patients with low back pain, and its correlation with age, sex, type of changes, number of involved segments and location of changes. Additionally, association of degenerative disc changes and disc herniation was assessed. Methods: In this retrospective study, MRI records of 229 patients with LBP referring to Medical Center of Hazrat-e-Rasoul Hospital, Tehran, Iran, from August to February 2014, were assessed and Modic changes and degenerative and herniated disc changes were recorded. Results: Based on our observations, a significant association between Modic type and age (P= 0.003) existed in patients with LBP. The highest prevalence in Modic location were observed in anterior part of vertebral endplate (48.8, P= 0.001). Although, observation of the Modic changes in superior vertebral endplate was higher than inferior parts, but this differences was not statistically significant. The highest prevalence in degenerative disc disease was disc dehydration which was observed in 18.1 of patients (P= 0.04). The relationship between the degenerative changes and Modic type was significant (P= 0.04), while the most prevalent change of disc contour was disc bulging which occurred in 23.7 of patients (P= 0.01). The highest frequency of abnormal disc contour were observed in Modic type 2 which was statistically significant (P= 0.01). Modic surface involvement above 25 was significantly associated with disc herniation (P= 0.04). There was no significant association between Modic height involvement above 25 and disc herniation. Conclusion: Considering significant association between Modic changes and degenerative and herniated disc changes, reporting of Modic changes is necessary. © 2016, Tehran University of Medical Sciences. All rights reserved

Diversity and distribution of octocorals and scleractinians in the Persian Gulf region

  This thesis reviews the available coral studies in the Persian Gulf at a large scale, discusses the environmental challenges for corals in the context of climate change, and expands our knowledge of coral biodiversity and biogeography of the region, highlights the remaining gaps in our knowledge and goes on to provide recommendations for further research. This is of special importance given recent international interest in the region as a harbinger of coral adaptation to climate change as the impacts to the global environment, human society and the economy unfold.  This thesis was accomplished with support from Naturalis Biodiversity Center (Martin Fellowship, A.M. Buitendijkfonds, J.J. Pelkwijkfonds), KNAW (Schure-Beijerinck-Poppingfonds), and Alfred P. Sloan Foundation, Census of Marine Life.Animal science