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What types of knee replacement devices are there?

Mobile-bearing devices offer a few extra degrees of rotation in the knee and work well for younger patients because they last longer and complement a more active lifestyle, says Healthline. Fixed-bearing devices are used in a majority of replacements, especially for older people who are less active who do not require a revision. Total knee replacements are the most common, but manufacturers also make devices for partial knee replacements that only require removal of part of the bone in the knee joint. A patient's posterior cruciate ligament may be removed or preserved during a total knee ..

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What is the dermis made of?

Glands in the dermis secrete sweat and sebum. Sweat aids in maintaining body temperature. Sebum is an oily substance that maintains skin moisture. Both sweat and sebum travel to the skin surface through small openings known as pores. The dermis is one of two layers of skin. It is located directly below the epidermis, which is the layer that comes in direct contact with the external environment. Several types of cells exist in the dermis, including fibroblasts, which are responsible for secreting the connective tissue.

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What happens in summer?

One important feature of the summer months in the northern hemisphere is hurricane season. The warmth the sun provides for the ocean causes an increase in the amount of moisture and heat that rises into the atmosphere, triggering cyclonic storms. Cyclone season runs from June 1st to November 30th, and some of the most devastating storms in history have occurred during the hottest months.\nThe longest day of the year in the northern hemisphere occurs on June 21st, and while this would seem to indicate the center of summer, meteorological summer tends to lag due to the heat-absorbing properties ..

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Why do we have national parks?

Yellowstone National Park was the first national park in the world and was established in 1872. At the time, its purpose was to protect the area for the enjoyment of future generations. Forty-four years later, in 1916, President Wilson officially signed the National Parks Service into law, establishing the agency to conserve the land surrounding important sites.\nToday, there are 400 National Park sites across all 50 states, encompassing a total of 84 million acres of land. Although these parks have entrance fees, they are usually quite small and well worth the cost. National parks can provide..

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Why is Venus hotter than Mercury?

The thick layer of carbon dioxide that surrounds Venus acts as a greenhouse. The gases let the heat from the sun in, but do not allow it to leave. This is the same process that happens on Earth with the increased amount of greenhouse gases, though it is much more severe on Venus because the atmosphere of Venus is around 90 times as thick. According to Discovery, carbon dioxide absorbs the heat that Venus tries to give off at night and keeps it on the planet, increasing the surface temperature to around 900 degrees Fahrenheit. The carbon dioxide also causes severe winds and storms on the surfac..

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What are examples of parasitism in the desert?

A parasitic relationship involves two organisms, but only one benefits. By taking needed nutrients from the organism, the parasite benefits itself over time, but the host organism suffers a result, often losing needed nutrients and other substances to the parasite.\nDesert mistletoe is a plant that grows on desert willow trees. The mistletoe attaches to the willow tree and takes the nutrients that it needs from the willow. This does not harm the willow tree, as long as the willow is taking in enough water and nutrients for itself and the desert mistletoe. However, if the environmental conditio..

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What is the difference between a protozoa and a bacteria?

Bacteria are generally smaller than protozoa, which frequently feed on bacteria. All protozoa "eat" by enveloping their prey within small pockets called vacuoles, while bacteria can absorb nutrients through their cell walls. Bacteria almost always reproduce via simple binary fission. While some protozoa also use this method, some split into more than two offspring, and some reproduce sexually.

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How can you find a calendar of holidays?

Holidays in the United States may be broadly divided into federal holidays, religious holidays and other holidays. Federal holidays are major holidays during which federal employees are granted the day off. Religious holidays are the dates of important religious observations for various faiths, and other holidays are largely cultural celebrations like Mother's Day, Valentine's Day or Halloween.

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How much electricity does a computer use per hour?

Running a computer for 8 hours a day uses about 50 kilowatts a month, which is 600 kilowatts a year. Laptops use one-quarter to one-third of this amount of electricity. Placing a computer in stand-by or sleep mode drops electricity use to about one-third of active use. Leaving a computer running 24 hours a day would use 144 kilowatts a month, or 1,728 kilowatts per year.

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What word describes the change in rock shape due to stress?

If the hinge of a fold, which refers to the point of sharpest curvature, points up, it is called an anticline. If the hinge of the fold points down, it is called a syncline. A recumbent fold is when the hinge of the fold points to the side. In regards to faulting, the deformation of the rock concentrates along the fractures. There are several types of faults: reverse, thrust, normal and strike-slip.

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