To improve the performance of short-range wireless communications, channel quality must be improved by avoiding interference and multi-path fading. Frequency hopping spread spectrum (FHSS) is a transmission technique where the carrier hops from frequency to frequency. For frequency hopping a mechanism must be designed so that the data can be transmitted in a clear channel and avoid congested ch...

Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse in...

The discovery of biological concepts can often provide a framework for the development of novel molecular tools, which can help us to further understand and manipulate life. One recent example is the elucidation of the prokaryotic adaptive immune system, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) that protects bacteria and archaea against viruses ...

CRISPR (clustered regularly interspaced short palindromic repeat) systems provide bacteria and archaea with adaptive immunity to repel invasive genetic elements. Type I systems use 'cascade' [CRISPR-associated (Cas) complex for antiviral defence] ribonucleoprotein complexes to target invader DNA, by base pairing CRISPR RNA (crRNA) to protospacers. Cascade identifies PAMs (protospacer adjacent m...

Orthogonal Frequency division multiplexing (OFDM) is a very attractive technique in wireless communications which provides robustness to channel fading and immunity to impulse interference. Despite of its advantages, one of the major drawbacks of OFDM system is very high peak-to-average power ratio (PAPR). Among the various PAPR reduction techniques, companding appears attractive for its simpli...

Next generation wireless communication system uses one of the most competent multicarrier transmission techniques known as Orthogonal Frequency Division Multiplexing (OFDM). OFDM has several characteristics such as providing greater immunity to multipath fading & impulse noise, eliminating Inter Symbol Interference (ISI) & Inter Carrier Interference (ICI) using a guard interval known as Cyclic ...

Wireless communications, for data services in particular, have witnessed an exponential growth, and wireless spectrum shortages necessitate increasingly sophisticated methods to use spectrum efficiently. The backhaul of nearly all wireless data networks is fiber-optic. Analog optical signal processing techniques, or microwave photonics, provides an ideal platform for processing wireless informa...

during a period of 7 years (1997-2003) we were received pairs of serum and csf of 27 suspicious clinically cases from neurology department of several hospitals in tehran. among them 7 were serologically positive for progressive rubella panencephalitis (prpe) and 2 were positive for sub acute sclerosing panencephalitis (sspe). rubella virus was isolated from 4 of 7 serologically positive cases o...

tetanus can be only prevented by vaccination because immunity against this disease is rarely acquired, even by natural infections. to maintain long-term protective immunity against tetanus, booster immunization is essential for adolescents and adults. most hospitalized cases and virtually all deaths occur in people over 60 years of age. the purpose of this study was to investigate the degree of...

neopterin, apyrazinopyrimidine compound, is produced by macrophages after induction by interferon gamma (ifn-y) and serves as a marker of cellular immune system activation followed by oxidative stress. the aim of this study was to determine urinary neopterin to creatinine ratio (uncr) as a surrogate marker of cell-mediated immune activation in multiple sclerosis (ms). three weekly early morning...