6G wireless communications networks: a comprehensive survey

The commercial fifth-generation (5G) wireless communications networks have already been deployed with the aim of providing high data rates. However, the rapid growth in the number of smart devices and the emergence of the Internet of Everything (IoE) applications, which require an ultra-reliable and low-latency communication, will result in a substantial burden on the 5G wireless networks. As such, the data rate that could be supplied by 5G networks will unlikely sustain the enormous ongoing data traffic explosion. This has motivated research into continuing to advance the existing wireless networks toward the future generation of cellular systems, known as sixth generation (6G). Therefore, it is essential to provide a prospective vision of the 6G and the key enabling technologies for realizing future networks. To this end, this paper presents a comprehensive review/survey of the future evolution of 6G networks. Specifically, the objective of the paper is to provide a comprehensive review/survey about the key enabling technologies for 6G networks, which include a discussion about the main operation principles of each technology, envisioned potential applications, current state-of-the-art research, and the related technical challenges. Overall, this paper provides useful information for industries and academic researchers and discusses the potentials for opening up new research directions

A New mmWave Antenna Array with Wideband Characteristics for Next Generation Communication Systems

This paper presents a planar multi-circular loop antenna with wide impedance bandwidth for next generation mm-wave systems. The proposed antenna comprises three circular rings with a partial ground plane having a square slot. The resonating structure is designed on a 0.254 mm thin RO5880 substrate with a relative permittivity of 2.3. The single element of the proposed de-sign showed resonance response from 26.5 to 41 GHz with peak gain of 4 dBi and radiation efficiency of 96%. The proposed multicircular ring antenna element is transformed into a four element array system. The array size is kept at 18.25 × 12.5 × 0.254 mm3 with a peak gain of 11 dBi. The antenna array is fabricated and measured using the inhouse facility. The simulated and measured results are well agreed upon and are found suitable for mmwave communication systems

Wireless Electromagnetic Radiation Assessment Based on the Specific Absorption Rate (SAR): A Review Case Study

Employing Electromagnetic Fields (EMFs) in new wireless communication and sensing technologies has substantially increased the level of human exposure to EMF waves. This paper presents a useful insight into the interaction of electromagnetic fields with biological media that is defined by the heat generation due to induced currents and dielectric loss. The Specific Absorption Rate (SAR) defines the heating amount in a biological medium that is irradiated by an electromagnetic field value. The paper reviews the radio frequency hazards due to the SAR based on various safety standards and organisations, including a detailed investigation of previously published work in terms of modelling and measurements. It also summarizes the most common techniques utilised between 1978 and 2021, in terms of the operational frequency spectrum, bandwidth, and SAR values

Influence of some data processing operations on the phase of seismic waves

Application of different processing techniques, based on different mathematical hypothesis, affects the amplitude and the shape of seismic wavelet. The phase changes resulting from the processing is discussed. Alignment of downgoing events in a vertical seismic profile, the velocity filter, the predictive deconvolution and the waves haping through appropriate windows, are studied. Investigation of the unaligned wavelet and down going alignment showed minimum phase changes. The predictive deconvolution (PON) shift the phase response of the measured seismic wavelet by 13.18 degrees

Leiomyoma of the urinary bladder: Case report

A case of leiomyoma of urinary bladder, a rare benign tumour, is presented. The patient was a 42 year old female who presented with dysuria and frequency of micturition. The radiological features, diagnosis and management are discussed and the literature on this subject is briefly reviewed. (East African Medical Journal: 2002 79(10): 557-559

A presentation of ulcerative colitis after rituximab therapy in a patient with multiple sclerosis and literature review

Multiple sclerosis (MS) is one of the most important demyelinating diseases that affects the central nervous system. Its treatment often involves a long-term disease modifying therapy. According to some studies, the prevalence of autoimmune disorders, such as autoimmune hepatitis (AIH) and ulcerative colitis (UC) is higher in MS patients than in the normal population. There are also few studies that have reported the onset of UC after rituximab therapy. The present study presents a report of a 31-years old female patient suffering from aggressive multiple sclerosis, which developed into autoimmune hepatitis during the MS therapy. Thereafter, she received rituximab for the treating both MS and AIH. One week after the third cycle of rituximab (6 doses of 1000 mg), she experienced abdominal pain, fever, and severe bloody diarrhea; finally, she was diagnosed with ulcerative colitis (UC). It seems that the administration of certain immunomodulators or immunosuppressive drugs may have a main role in the exacerbation of some autoimmune diseases. © 2018 Elsevier B.V

A presentation of ulcerative colitis after rituximab therapy in a patient with multiple sclerosis and literature review

Multiple sclerosis (MS) is one of the most important demyelinating diseases that affects the central nervous system. Its treatment often involves a long-term disease modifying therapy. According to some studies, the prevalence of autoimmune disorders, such as autoimmune hepatitis (AIH) and ulcerative colitis (UC) is higher in MS patients than in the normal population. There are also few studies that have reported the onset of UC after rituximab therapy. The present study presents a report of a 31-years old female patient suffering from aggressive multiple sclerosis, which developed into autoimmune hepatitis during the MS therapy. Thereafter, she received rituximab for the treating both MS and AIH. One week after the third cycle of rituximab (6 doses of 1000 mg), she experienced abdominal pain, fever, and severe bloody diarrhea; finally, she was diagnosed with ulcerative colitis (UC). It seems that the administration of certain immunomodulators or immunosuppressive drugs may have a main role in the exacerbation of some autoimmune diseases. © 2018 Elsevier B.V