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In this paper, a very accurate approximation method for the statistics of the sum of M\'{a}laga-$\mathcal{M}$ random variates with pointing error (MRVs) is proposed. In particular, the probability density function of MRV is approximated by a Fox's $H$-function through the moment-based approach. Then, the respective moment-generating function of the sum of $N$ MRVs is provided, based on which the average symbol error rate is evaluated for an $N $-branch maximal-ratio combining (MRC) receiver. The retrieved results show that the proposed approximate results match accurately with the exact simulated ones. Additionally, the results show that the achievable diversity order increases as a function of the number of MRC diversity branches., Comment: 6 pages, 6 figures

In this paper, the performance of a dual-hop energy harvesting-based fixed-gain amplify-and-forward (AF) relaying communication system, subject to fading impairments, is investigated. We consider a source node ($S$) communicating with a destination node ($D$) through a fixed distant relay ($R$), which harvests energy from its received signals and uses it to amplify and forward the received signals to $D$. Power-splitting (PS) and time-switching (TS) schemes are considered in the analysis for energy harvesting. The $S$-$R$ and $R$-$D$ hops are modeled by the Nakagami-$m$ and $\alpha $-$\mu $ fading models, respectively. Closed-form expressions for the statistical properties of the end-to-end signal-to-noise ratio (SNR) are derived, based on which novel closed-form expressions for the average symbol error rate (ASER) as well as average channel capacity (ACC) considering four adaptive transmission policies are derived. The derived expressions are validated through Monte-Carlo simulations., Comment: 11 pages, 10 figures

Hybrid terrestrial-satellite (HTS) communication systems have gained a tremendous amount of interest recently due to the high demand for global high data rates. Conventional satellite communications operate in the conventional Ku (12 GHz) and Ka (26.5-40 GHz) radio-frequency bands for assessing the feeder link, between the ground gateway and the satellite. Nevertheless, with the aim to provide hundreds of Mbps of throughput per each user, free-space optical (FSO) feeder links have been proposed to fulfill these high data rates requirements. In this paper, we investigate the physical layer security performance for a hybrid very high throughput satellite communication system with an FSO feeder link. In particular, the satellite receives the incoming optical wave from an appropriate optical ground station, carrying the data symbols of $N$ users through various optical apertures and combines them using the selection combining technique. Henceforth, the decoded and regenerated information signals of the $N$ users are zero-forcing (ZF) precoded in order to cancel the interbeam interference at the end-users. The communication is performed under the presence of malicious eavesdroppers nodes at both hops. Statistical properties of the signal-to-noise ratio of the legitimate and wiretap links at each hop are derived, based on which the intercept probability metric is evaluated. The derived results show that above a certain number of optical apertures, the secrecy level is not improved further. Also, the system's secrecy is improved using ZF precoding compared to the no-precoding scenario for some specific nodes' positions. All the derived analytical expressions are validated through Monte Carlo simulations., Comment: 17 pages, 10 figures

In this paper, an improved numerical solver to evaluate the time-dependent radiative transfer equation (RTE) for underwater optical wireless communications (UOWC) is investigated. The RTE evaluates the optical path-loss of light wave in an underwater channel in terms of the inherent optical properties related to the environments, namely the absorption and scattering coefficients as well as the phase scattering function (PSF). The proposed numerical algorithm was improved based on the ones proposed in [1]-[4], by modifying the finite difference scheme proposed in [1] as well as an enhancement of the quadrature method proposed in [2] by involving a more accurate 7-points quadrature scheme in order to calculate the quadrature weight coefficients corresponding to the integral term of the RTE. Furthermore, the scattering angular discretization algorithm used in [3] and [4] was modified, based on which the receiver's field of view discretization was adapted correspondingly. Interestingly, the RTE solver has been applied to three volume scattering functions, namely: the single-term HG phase function, the two-term HG phase function [5], and the Fournier-Forand phase function [6], over Harbor-I and Harbor-II water types. Based on the normalized received power evaluated through the proposed algorithm, the bit error rate performance of the UOWC system is investigated in terms of system and channel parameters. The enhanced algorithm gives a tightly close performance to its Monte Carlo counterpart improved based on the simulations provided in [7], by adjusting the numerical cumulative distribution function computation method as well as optimizing the number of scattering angles. Matlab codes for the proposed RTE solver are presented in [8].

INTRODUCTION: The preservation of the integrity and health of primary teeth and their supporting tissues is of great importance in maintaining arch length space, mastication, speech, and esthetics. A pulpotomy is a common therapy performed on a primary tooth presenting reversible pulpitis or a traumatic pulp exposure, allowing its conservation on the arch until its loss. AIM: The study aims to clinically and radiographically evaluate the rates of success and efficacy of Biodentine™ as pulpotomy medicament exclusively on deciduous molars with complete roots formation (stage 2). MATERIALS AND METHODS: A total number of 75 primary molars in stage 2 of formation were selected to undergo pulpotomy treatment. All teeth were restored with a stainless-steel crown.The clinical success was evaluated at 1, 3, 6 and 12-month intervals. The radiographic follow-up evaluations were at 6 and 12 months. The resulting data were tabulated and statistically analyzed. RESULTS: Among the 75 teeth treated with Biodentine™, one tooth revealed abnormal mobility and tenderness to percussion at the end of the 1st month. PLS widening and the bone lesion was not seen in any of the 74 remaining cases. Forty teeth (54.1%) showed pulp canal obliteration (PCO), and none of the cases developed a draining sinus or had increased mobility. At the end of the 1-year follow-up, the clinical and radiographic success rates were 98.7% and 100%, respectively. CONCLUSION: Pulpotomies performed with Biodentine™ on stage 2 primary molars were generally very satisfactory and fulfilled all requirements, covering all needs. This innovative bioactive medicament seems to be a "heroic" material. The excellent outcomes of the present study are indicative that Biodentine™ is a promising biomaterial to promote pulp repair after pulpotomy in clinical practice. HOW TO CITE THIS ARTICLE: Nasrallah H, El Noueiri B, Pilipili C, Ayoub F. Clinical and Radiographic Evaluations of Biodentine™ Pulpotomies in Mature Primary Molars

INTRODUCTION: Conservation of primary dentition is essential for maintenance of arch length, esthetic, mastication, speech and prevention of abnormal habits. The commonly supported treatment for retaining carious primary molars with affected pulp is pulpotomy. AIM: The study aims to evaluate clinically and radiographically the rates of success and efficacy of Biodentine™ as pulpotomy medicament exclusively on primary molars with physiological root resorption. MATERIALS AND METHODS: A total number of 35 primary molars in stage three of formation were selected to undergo pulpotomy treatment. All teeth were restored with pediatric stainless-steel crowns.The clinical findings were evaluated at 1, 3, 6 and 12-month intervals and the radiographic follow-ups evaluations were done at 6 and 12 months. The resulting data were tabulated and statistically analyzed using IBM SPSS© for Windows version 20.0 (SPSS, Chicago, IL, USA). Mc Nemar test was conducted to evaluate the differences in results between months 6 and 12. RESULTS: Periodontal ligament space (PLS) widening and alveolar bone lesion were not seen in any of the 35 cases, 9 teeth (25.7%) manifested pulp canal obliteration (PCO), and none of the cases showed signs of pathologic root resorption. The clinical and radiographic success rates in pulpotomy using Biodentine™ at 6 and 12 months were 100%. CONCLUSION: Pulpotomies performed with Biodentine™ were entirely successful. This dressing material appears to be a serious pulpotomy agent in primary molars with root resorption.How to cite this article: Nasseh HN, Noueiri BE, Pilipili C, Ayoub F. Evaluation of Biodentine Pulpotomies in Deciduous Molars with Physiological Root Resorption (Stage 3).