Girls approaching adolescence may experience clear or white vaginal discharge before their first period, which may be light. The first year of menstruation is usually irregular, but periods falling within 22 to 35 days are considered normal. Common menstrual symptoms in girls include cramps, swelling, tender breasts, mood swings, and food cravings. Many girls approaching […]
When buying a flash MP3 player, consider memory capacity, external flash memory cards, playlist creation, file compatibility, custom EQ, advanced system options, LCD window size, FM tuner, voice recorder, and rechargeable battery vs AAA. Prices range from under $20 to over $200. There is no shortage of choice when it comes to buying a flash […]
Interactive resources for learning and education include books, movies, computer programs, and games. They can be subject-specific or adaptable, and many are freely available. Interactive features can greatly improve learning, and resources can be found without technology, such as activity books, or with technology, such as films and computer programs. There are many different types […]
Linux is a free and open source operating system that is highly customizable and cross-platform. It allows multiple users to be logged in at the same time and has a large community for support. Linux can run on various hardware and comes with pre-installed software. It can be modified for optimal performance but lacks support […]
The abyssal plain covers 40% of the ocean floor, is flat due to slow sediment accumulation, and is sparsely populated by bottom feeders. Hydrothermal vents, cold seeps, and whale falls provide oases for small ecosystems. Less than 0.1% of the abyssal plain has been explored by humans. The ocean floor off the continental shelf is […]
The Earth’s core has two parts, the inner and outer, with the outer being mostly liquid iron and nickel. The inner core was thought to be a single crystal of iron, but recent theories suggest it is made up of dissimilar parts. The outer core is responsible for the Earth’s magnetic field and circulates due […]
Pluto is a dwarf planet in the outer solar system, second largest in the Kuiper belt. Discovered in 1930, it has a brownish color, three moons, and an average surface temperature of 49 K. The New Horizons spacecraft will approach Pluto in 2015. Pluto is an outer solar system body formerly known as a planet, […]
Jupiter is a gas giant with a volume of 1321 Earths and a mass of 318 Earths. It has 63 moons, including the Galilean moons, and a powerful magnetic field that causes volcanic activity on Io. Jupiter’s Great Red Spot is a circular storm many times the size of Earth. It absorbs comets and asteroids […]
The Moon’s maria are basaltic lavas, not seas. Impact craters, including Daedalus and Copernicus, were left by billions of years of impacts. The Moon is the fifth-largest natural satellite and has been visited by humans. It may be a target for extraterrestrial colonization. The Moon’s most prominent features are its maria, Latin for “seas,” because […]
Venus is Earth’s “sister planet” with a different surface, 96.5% carbon dioxide atmosphere, and a surface temperature of 462°C. It appears as the brightest object in the night sky and is named after the Roman goddess of love. Several missions have been sent to Venus, confirming its extreme heat and lack of life. The US […]
Mercury is a small planet with a large iron core and a surface temperature of -292 to 806°F. It has been observed from Earth since ancient times and is the smallest planet in the solar system. Theories about its core include an impact-based theory, a super-hot atmospheric envelope, and the drag of a protosolar nebula. […]
Bacteria are the most common organisms on Earth, with a variety of shapes and sizes. They have a simple structure, but internal plasmids give them unique abilities. Bacterial DNA determines other characteristics such as pili, flagella, and cytoskeleton. Modern molecular genetics and advanced microscopy are helping us learn more about them. Bacteria are the most […]
The asteroid belt, containing 98.5% of known asteroids, is stable due to gravitational interactions between the Sun and Jupiter. It is relatively sparse and could be a source of resources. The belt will never merge into a planet due to constant collisions and the dust produced creates zodiacal light. The asteroid belt contains 98.5% of […]
Caves contain various speleothems, such as stalactites and stalagmites, which grow slowly over centuries or millennia. Other formations include soda straws, helictites, and flowstone. These structures are created by dripping water depositing calcite or gypsum. The caves of the world contain numerous beautiful and mysterious formations for anyone brave enough to venture into them. There […]
A decision support system provides information for informed decision-making, with features such as facilitation, interaction, and task-oriented activities. It can handle multiple tasks and may be customized to meet a business’s needs. A decision support system is an internal business asset that provides owners, managers and other employees with information to make informed decisions. Common […]
Economists use GDP and retail sales to predict economic growth. Increased production and consumption of goods and services lead to public and business benefits. Obstacles to growth include inefficient resource production and consumption. Retail spending during growth provides valuable insights to economists. While it may seem that changes in the economy are sudden, there are […]
