The study of good nonregular fractional factorial designs has received significant attention over the last two decades. Recent research indicates that designs constructed from quaternary codes (QC) are very promising in this regard. The present paper shows how a trigonometric approach can facilitate a systematic understanding of such QC designs and lead to new theoretical results covering hithe...

Adolescents and youth aged 15-24 are one of the populations most impacted by the global HIV epidemic with an estimated 50% of new infections occurring in this age group. They are thus one of the prime populations for targeting behavioral and biomedical preventions. However, the dynamics of the HIV epidemic in youth vary widely by geographic region and risk behavior profiles. There are also biol...

benzalkonium chloride is a quaternary ammounium compounds derivative under different names such as afxhang, hamoon, mahan etc, which have great and expanded use in sanitation and medical affairs. bactericidal activity of these disinfectants was fulfilled according to national standard method no.2842 on staph. aureus, sal. typhimouium and e. coli. this laboratory test showed that, except mahan t...

palynological analyses from exposed palaeolacustrine deposits located at the flanks of damavand volcano, in the central alborzmountains in northern iran, provide a broad idea of the temporal variation of vegetation according to climate changes during a rangeof limited time intervals during the quaternary period. this research reveals that the regional vegetation of the study area had been asemi...

Two biodegradable quaternary ammonium salts were synthesized and used as cationic collectors in processing iron ores by froth flotation. The flotation behaviors of iron minerals with the new biodegradable quaternary ammonium collectors were investigated by micro-flotation tests of quartz (SiO2) and magnetite (Fe3O4). It was observed that the new biodegradable collectors were effective in separa...

Multi-valued logic gates, which can handle quaternary numbers as inputs, are developed by exploiting the ballistic transport properties of quantum point contacts in series. The principle of a logic gate that finds the minimum of two quaternary number inputs is demonstrated. The device is scalable to allow multiple inputs, which makes it possible to find the minimum of multiple inputs in a singl...

Four-level (quaternary) signalling in optical communication systems is investigated and the optimisation of quaternary signal level spacing is carried out considering signalamplified spontaneous emission beat noise dominance. The optimised quaternary signal is propagated through an optical dispersive fibre and sensitivity improvements can be found for shorter transmission distances and non-zero...