The overtaking collisional phenomenon of slow shear Alfvén solitons are studied in a low beta (β = kinetic pressure/magnetic pressure) collisionless, magnetized plasma consisting of electron and ion fluids. By employing a reductive perturbation technique, the Korteweg–de Vries (KdV) equation is deduced for investigating the nonlinear slow shear Alfvén wave. Before embarking on the study of the overtaking collisions, the stability analysis of the KdV equation is studied using the bifurcation theory. Also, a nonlinear periodic solution of the KdV equation is derived for the first time in the Weierstrass elliptic function formula. Moreover, the condition for converting the Weierstrass elliptic function expression to soliton is discussed. Furthermore, it is found that only density dip (rarefactive) solitons are formed in the super-Alfvénic regime. The next step includes the use of the Hirota bilinear method, which results in two and three shear Alfvén soliton solutions and their subsequent phase shifts. The influence of the plasma parameters on the amplitude as well as width of the slow shear Alfvén wave solitons are examined analytically and numerically. We also find out the profiles of overtaking interaction of slow shear Alfvén dip solitons having different amplitudes and speeds numerically. This study is important for understanding the phenomena of nonlinear slow shear Alfvén wave structures both in space and in laboratory plasmas.

Tuberculosis (TB) is now the most common infectious cause of death worldwide. In 2014, an estimated 9.6 million people developed active TB. There were an estimated three million people with active TB including 360000 with multidrug-resistant TB (MDR-TB) who were not diagnosed, and such people continue to fuel TB transmission in the community. Accurate data on the actual burden of TB and the transmission risk associated with mass gatherings are scarce and unreliable due to the small numbers studied and methodological issues. Every year, an estimated 10 million pilgrims from 184 countries travel to the Kingdom of Saudi Arabia (KSA) to perform the Hajj and Umrah pilgrimages. A large majority of pilgrims come from high TB burden and MDR-TB endemic areas and thus many may have undiagnosed active TB, sub-clinical TB, and latent TB infection. The Hajj pilgrimage provides unique opportunities for the KSA and the 184 countries from which pilgrims originate, to conduct high quality priority research studies on TB under the remit of the Global Centre for Mass Gatherings Medicine. Research opportunities are discussed, including those related to the definition of the TB burden, transmission risk, and the optimal surveillance, prevention, and control measures at the annual Hajj pilgrimage. The associated data are required to develop international recommendations and guidelines for TB management and control at mass gathering events.

This investigation analyzes the propagation of nonlinear ion-acoustic waves (IAWs) in an unmagnetized, collisionless plasma composed of inertial positive ions and inertialess Maxwellian positrons as well as the inertialess non-Maxwellian electrons that obey (r, q)-distribution. To observe the impact of particle trapping on the nonlinear IAWs in an electron–positron–ion plasma, the Korteweg–De Vries (KdV) and modified KdV (mKdV) equations are derived using a reductive perturbation method. In the distribution function, the spectral parameters (r, q) put up their contribution to the flatness and high-energy tails, respectively. An important aspect of this investigation is the determination of well-known quasi-periodic solutions, multi-soliton solutions, breathers, and shocks under the variation of different physical parameters, especially spectral indices (r, q). Finally, the interaction of solitons is also presented for discussion of the complete profile. In addition, a detailed comparison, especially in a periodic wave, is made between the generalized (r, q)-distribution and the limiting cases of Kappa and Maxwellian distributions. The results presented in this study contribute to a better understanding of the characteristics of both high- and low-energy parts of the electron distribution function as well as the formation of periodic, soliton, multi-soliton, breathers, and shocks in space and astrophysical plasmas.

This study investigates the distribution of natural radioactivity and geological, geochemical, and environmental risk assessments of phosphorite deposits to determine their suitability for international applications (such as phosphoric acid and phosphatic fertilizers). The examined Late Cretaceous phosphorite deposits belong to the Duwi Formation, which is well exposed on the southern scarp boundary at the central part of Abu Tartur Plateau, Gebel Qulu El Sabaya, East Dakhla Oasis. This formation is classified into lower phosphorite, middle shale, and upper phosphorite members. The lower phosphorite ranges in thickness from 2 to 3.5 m and mainly comprises apatite (possibly francolite), dolomite, calcite, quartz, hematite, anhydrite, and kaolinite. They contain an average concentration of CaO (38.35 wt.%), P₂O₅ (24.92 wt.%), SiO₂ (7.19 wt.%), Fe₂O₃ (4.18 wt.%), MgO (3.99 wt.%), F (1.59 wt.%), Al₂O₃ (1.84 wt.%), Na₂O (1.33 wt.%), and K₂O (0.22 wt.%). Natural radioactivity and radiological parameters were investigated for fifteen samples of phosphorites using a NaI (Tl) scintillation detector. Absorbed dose rates, outdoor and indoor annual effective dose, radium equivalent activity, external and internal hazard, and excess cancer risk values are higher than the recommended levels, reflecting that exposure to these deposits for a long time may lead to health risks to human organs.