Before a man’s sperm can fertilize a woman’s egg, the head of the sperm must attach to the outside of the egg. Once attached, the sperm pushes through the outer layer to the inside of the egg (cytoplasm), where fertilization takes place. Sometimes the sperm cannot penetrate the outer layer, for a variety of reasons. The egg’s outer layer may… Read more →
White dwarfs are dead stars. A single white dwarf contains roughly the mass of our sun in a volume no bigger than our planet. Our sun will become a white dwarf someday. White dwarfs are the hot, dense remnants of long-dead stars. They are the stellar cores left behind after a star has exhausted its fuel supply and blown its… Read more →
There are two basic types of sleep: rapid eye movement (REM) sleep and non-REM sleep (which has three different stages). Each is linked to specific brain waves and neuronal activity. You cycle through all stages of non-REM and REM sleep several times during a typical night, with increasingly longer, deeper REM periods occurring toward morning. Stage 1 non-REM sleep is… Read more →
It may seem a little embarrassing: you wake up and your pillow is drenched in slobber. After you wipe the spit at the corners of your mouth, you might wonder: Why do we drool in our sleep? The body normally produces more than 1 liter of saliva per day. It is produced by salivary glands and is usually swallowed and… Read more →
A monorail is a rail-based transportation system based on a single rail, which acts as its sole support and its guideway. The term is also used variously to describe the beam of the system, or the vehicles travelling on such a beam or track. Monorails have been around since the 1800s, but only really came to public attention in the… Read more →
A mammogram is an x-ray picture of the breast. It can be used to check for breast cancer in women who have no signs or symptoms of the disease. It can also be used if you have a lump or other sign of breast cancer. Screening mammography is the type of mammogram that checks you when you have no symptoms.… Read more →
Anti drone systems are used to detect and/or intercept unwanted drones and unmanned aerial vehicles (UAVs). Hostile drones may be used to deploy explosives, smuggle contraband or gather intelligence on sensitive assets, and the proliferation of low-cost UAVs has led to an increase in incidents. Anti drone technology is deployed to protect areas such as airports, critical infrastructure, large public… Read more →
Railway sleepers, also called railroad ties, railway ties or crossties, are an important railway component. Generally, the rail sleeper is always laying between two rail tracks to keep the correct space of the gauge. In recent time, concrete sleepers are widely used, especially in Europe and Asia. And in the UK, steel ties are common. Besides, plastic composite ties are… Read more →
Most often used in foggy conditions, is a device that uses sound to warn vehicles of hazards. Generally, marine transport is using the term. When lighthouses are obscured the foghorn provides an audible warning of any dangers to ships. Robert Foulis created the first automated steam-powered foghorn. After hearing his daughter play piano in the fog, he realized the lower… Read more →
Dredging is the removal of sediments and debris from the bottom of lakes, rivers, harbours, and other water bodies. It is a routine necessity in waterways around the world because sedimentation, the natural process of sand and silt washing downstream gradually fills channels and harbours. Dredging often is focused on maintaining or increasing the depth of navigation channels, anchorages, or… Read more →
