Classifications, properties, recent synthesis and applications of azo dyes.

Fifth-generation (5G) cellular networks will almost certainly operate in the high-bandwidth, underutilized millimeter-wave (mmWave) frequency spectrum, which offers the potentiality of high-capacity wireless transmission of multi-gigabit-per-second (Gbps) data rates. Despite the enormous available bandwidth potential, mmWave signal transmissions suffer from fundamental technical challenges like severe path loss, sensitivity to blockage, directivity, and narrow beamwidth, due to its short wavelengths. To effectively support system design and deployment, accurate channel modeling comprising several 5G technologies and scenarios is essential. This survey provides a comprehensive overview of several emerging technologies for 5G systems, such as massive multiple-input multiple-output (MIMO) technologies, multiple access technologies, hybrid analog-digital precoding and combining, non-orthogonal multiple access (NOMA), cell-free massive MIMO, and simultaneous wireless information and power transfer (SWIPT) technologies. These technologies induce distinct propagation characteristics and establish specific requirements on 5G channel modeling. To tackle these challenges, we first provide a survey of existing solutions and standards and discuss the radio-frequency (RF) spectrum and regulatory issues for mmWave communications. Second, we compared existing wireless communication techniques like sub-6-GHz WiFi and sub-6 GHz 4G LTE over mmWave communications which come with benefits comprising narrow beam, high signal quality, large capacity data transmission, and strong detection potential. Third, we describe the fundamental propagation characteristics of the mmWave band and survey the existing channel models for mmWave communications. Fourth, we track evolution and advancements in hybrid beamforming for massive MIMO systems in terms of system models of hybrid precoding architectures, hybrid analog and digital precoding/combining matrices, with the potential antenna configuration scenarios and mmWave channel estimation (CE) techniques. Fifth, we extend the scope of the discussion by including multiple access technologies for mmWave systems such as non-orthogonal multiple access (NOMA) and space-division multiple access (SDMA), with limited RF chains at the base station. Lastly, we explore the integration of SWIPT in mmWave massive MIMO systems, with limited RF chains, to realize spectrally and energy-efficient communications.

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A Comprehensive Survey on Millimeter Wave Communications for Fifth-Generation Wireless Networks: Feasibility and Challenges

Background—The role of coronary stenting in the treatment of patients with small vessels is not well defined. The purpose of this study was to investigate the influence of vessel size on long-term clinical and angiographic outcome after coronary stent placement. Methods and Results—The study comprised 2602 patients with successful stent implantation for symptomatic coronary artery disease. Patients were subdivided into 3 equally sized groups (tertiles) according to vessel size, with respective ranges of 3.2 mm. Event-free survival at 1 year was 69.5% in the group with smaller vessels, 77.5% in the second group, and 81% in the group with larger vessels (P<0.001). Late lumen loss was similar between the 3 groups (1.12±0.73, 1.12±0.79, and 1.09±0.88 mm, respectively). Angiographic restenosis rate was significantly higher in the small-vessel group (38.6%, 28.4%, and 20.4% in groups 1, 2, and 3, respectively; P<0.001). The analysis identified subgroups with different risk for restenosis ...

Vessel Size and Long-Term Outcome After Coronary Stent Placement

drugs. If the co-operation, therefore, between physician and surgeon is indispensable to the patient's welfare, it has become equally indispensable to the preparation of a modem manual. These two volumes comprise a collection of essays contributed by experts in their particular subject. It was not designed as a textbook; yet it has become if not a textbook in name, certainly a work of reference in fact. A vast deal of ground has been covered with remarkably little overlap considering the number of individual contributors. The first volume is concerned chiefly with the general aspects of the subject, such as epidemiology, the clinical and laboratory diagnosis of the disease, morbid anatomy, radiology, administration and rehabilitation. The minimal lesion with its special problems, fluorography, B.C.G. inoculation, psychology and tuberculosis in industry are all discussed. The second volume deals with the disease more precisely by systems and contains accounts of the surgical methods employed in treatment. Considering the entire work it can be said that the main editorial difficulty of blending so large a number of separate contributions into a composite whole has been overcome. The result is a manual that is authoritative and complete, and one which will enhance the prestige of British medical practice.

A Short Practice of Surgery

In this paper, real measurements were conducted to investigate the impact of rain on the propagation of millimeter waves at 26 GHz. The measurements were accomplished using a microwave fifth generation radio link system with 1.3 km path length implemented at Universiti Teknologi Malaysia Johor Bahru, Malaysia. The implemented system consisted of Ericsson CN500 mini E-link, radio unit, rain gauge, and data logger. The measurements were attained and logged daily for a continuous year, with 1-min time intervals. Next, the MATLAB software was used to process and analyze the annual rain rate and rain attenuation, including for the worst month. From the analyzed results, it was found that at 0.01% percentage of time, the rain rate was 120 mm/hr; while the specific rain attenuation was 26.2 dB/km and the total rain attenuation over 1.3 km was 34 dB. In addition, the statistics acquired from the measurements for the worst month were lower than what was predicted by the international telecommunication union (ITU) model; around 51% and 34% for the rain rate and rain attenuation, respectively. The average percentage of error calculated between the measurements and predicted results for the rain rate and rain attenuation were 143% and 159%, respectively. Thus, it can be concluded that the statistics for the worst month in Malaysia is lower than what was predicted by the ITU model.

Real Measurement Study for Rain Rate and Rain Attenuation Conducted Over 26 GHz Microwave 5G Link System in Malaysia

Rain attenuation statistics over millimeter wave bands in South Korea

The attenuation induced by rain is prominent in the satellite communication at Ku and Ka bands. The paper studied the empirical determination of the power law coefficients which support the calculation of specific attenuation from the knowledge of rain rate at Ku and Ka band for Koreasat 6 and COMS1 in South Korea that are based on the three years of measurement. Rain rate data was measured through OTT Parsivel which shows the rain rate of about 50 mm/hr and attenuation of 10.7, 11.6, and 11.3 dB for 12.25, 19.8, and 20.73 GHz, respectively, for 0.01% of the time for the combined values of rain rate and rain attenuation statistics. Comparing with the measured data illustrates the suitability for estimation of signal attenuation in Ku and Ka band whose validation is done through the comparison with prominent rain attenuation models, namely, ITU-R P.618-12 and ITU-R P. 838-3 with the use of empirically determined coefficient sets. The result indicates the significance of the ITU-R recommended regression coefficients of rain specific attenuation. Furthermore, the overview of predicted year-wise rain attenuation estimation for Ka band in the same link as well as different link is studied which is obtained from the ITU-R P. 618-12 frequency scaling method.

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Characterization of Rain Specific Attenuation and Frequency Scaling Method for Satellite Communication in South Korea

Ambient endotoxin in PM10 and association with inflammatory activity, air pollutants, and meteorology, in Chitwan, Nepal.

Indium tin oxide (ITO) is one of the most widely used transparent conductors in optoelectronic device applications. We investigated the optical properties of ITO thin films at high temperatures up to 800 °C using spectroscopic ellipsometry. As temperature increases, amorphous ITO thin films undergo a phase transition at ~ 200 °C and develop polycrystalline phases with increased optical gap energies. The optical gap energies of both polycrystalline and epitaxial ITO thin films decrease with increasing temperature due to electron–phonon interactions. Depending on the background oxygen partial pressure, however, we observed that the optical gap energies exhibit reversible changes, implying that the oxidation and reduction processes occur vigorously due to the low oxidation and reduction potential energies of the ITO thin films at high temperatures. This result suggests that the electronic structure of ITO thin films strongly depends on temperature and oxygen partial pressure while they remain optically transparent, i.e., optical gap energies > 3.6 eV.

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High-temperature optical properties of indium tin oxide thin-films.

It is known that the widely used public key cryptosystems such as RSA and elliptic curve cryptography can be broken by using a specific computation in quantum computers. Currently, since quantum computers which can deal with practical length of parameters are not realized yet, we may still use the famous cryptographic algorithms. However, we need to prepare and deeply study the alternatives of these algorithms before the realization of the practical quantum computers and this line of research is called as the ‘post-quantum cryptography (PQC).’ In this paper, we study a candidate of post-quantum cryptography, a new version of McEliece crypto-system based on polar codes, which are recently proposed promising error correcting codes in many applications.

Sujan Shrestha

Papers

Rain attenuation statistics over millimeter wave bands in South Korea

Characterization of Rain Specific Attenuation and Frequency Scaling Method for Satellite Communication in South Korea

Ambient endotoxin in PM10 and association with inflammatory activity, air pollutants, and meteorology, in Chitwan, Nepal.

High-temperature optical properties of indium tin oxide thin-films.

New McEliece cryptosystem based on polar codes as a candidate for post-quantum cryptography