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The oceanic whitetip shark, Carcharhinus longimanus, is a large pelagic shark inhabiting tropical and warm temperate seas. Its stocky body is most notable for its long, white-tipped, rounded fins. This aggressive but slow-moving fish dominates feeding frenzies, and is a danger to shipwreck or air crash survivors. Recent studies show steeply declining populations because its large fins are highly valued as the chief ingredient of shark fin soup and, as with other shark species, the whitetip faces mounting fishing pressure throughout its range. The oceanic whitetip is found globally in deep, open water, with a temperature greater than 18 °C (64 °F). It prefers waters between 20 °C (68 °F) and 28 °C (82 °F) and tends to withdraw from areas when temperatures fall below this. They were once extremely common and widely distributed, and still inhabit a wide band around the globe; however, recent studies suggest that their numbers have drastically declined. An analysis of the US pelagic longline logbook data between 1992–2000 (covering the Northwest and Western Central Atlantic) estimated a decline of 70% over that period. The whitetip feeds mainly on pelagic cephalopods and bony fish. However, its diet can be far more varied and less selective—it is known to eat threadfins, stingrays, sea turtles, birds, gastropods, crustaceans, mammalian carrion, and even rubbish dumped from ships. The bony fish it feeds on include lancetfish, oarfish, barracuda, jacks, dolphinfish, marlin, tuna, and mackerel. Its feeding methods include biting into groups of fish and swimming through schools of tuna with an open mouth. When feeding with other species, it becomes aggressive. Peter Benchley, author of Jaws, observed this shark swimming among pilot whales and eating their feces. During World War II, the Nova Scotia, a steamship carrying approximately 1,000 people near South Africa, was sunk by a German submarine. With only 192 survivors, many deaths were attributed to the whitetip. The whitetip poses a minimal threat to bathers or inshore sportsman, but a high risk for humans caught in the open ocean. Although the whitetip is opportunistic and aggressive, and may attack humans for food, divers have swum with this shark repeatedly without incident. Divers are advised to approach the shark only with extreme caution, to not spear fish near this shark and, if the shark comes too close or gets too inquisitive, to get out of the water as soon as possible. [READ THE REST OF THIS ARTICLE]

Chironex fleckeri, the infamous lethally venomous species of Box jellyfish living in northern Australia's coastal waters, is the most lethal jellyfish in the world, and one of the most dangerous animals in the world. The amount of venom in one animal is enough to kill 60 adult humans. First aid consists of washing the sting area with vinegar, and in no circumstance should alcohol, alcohol-based lotions, or methylated spirits be applied. Chironex fleckeri is best known for its incredibly powerful and often fatal sting. The sting produces excruciating pain accompanied by an intense burning sensation, and the venom has multiple effects attacking the nervous system, heart and skin at the same time. While an appreciable amount of venom (contact from about ten feet or three metres of tentacle) needs to be delivered in order to have a fatal effect on an adult human, the potently neurotoxic venom is extremely quick to act. Fatalities have been observed as little as four minutes after envenomation, notably quicker than any snake, insect or spider , and prompting its description as the world's deadliest venomous animal. Frequently a person swimming who gets stung will have a heart attack or drown before they can even get back to the shore or boat. Cardiopulmonary resuscitation (CPR) may be required. Medical help should be sought as soon as possible after considering these needs. Notorious for its dangerous sting, C. fleckeri tentacles, up to 3m long, are covered in thousands upon thousands of nematocysts which on contact release microscopic darts, each delivering an extremely powerful venom. Being stung invariably results in excruciating pain, and if the sting area is significant, an untreated victim may die in as little as 3 minutes. Swimmers who are stung face the additional risk of drowning. [READ THE REST OF THIS ARTICLE]

A spinal disc herniation, informally and misleadingly called a "slipped disc", is a medical condition affecting the spine, in which a tear in the outer, fibrous ring of an intervertebral disc allows the soft, central portion (nucleus pulposus) to bulge out. Tears are almost always postero-lateral in nature owing to the presence of the posterior longitudinal ligament in the spinal canal. This tear in the disc ring may result in the release of inflammatory chemical mediators which may directly cause severe pain, even in the absence of nerve root compression. This is the rationale for the use of anti-inflammatory treatments for pain associated with disc herniation, protrusion, bulge, or disc tear. It is normally a further development of a previously existing disc protrusion, a condition in which the outermost layers of the annulus fibrosus are still intact, but can bulge when the disc is under pressure. Symptoms of a herniated disc can vary depending on the location of the herniation and the types of soft tissue that become involved. They can range from little or no pain if the disc is the only tissue injured, to severe and unrelenting neck or low back pain that will radiate into the regions served by affected nerve roots that are irritated or impinged by the herniated material. Often, herniated discs are not diagnosed immediately, as the patients come with undefined pains in the thighs, knees, or feet. Other symptoms may include sensory changes such as numbness, tingling, muscular weakness, paralysis, paresthesia, and affection of reflexes. If the herniated disc is in the lumbar region the patient may also experience sciatica due to irritation of one of the nerve roots of the sciatic nerve. Unlike a pulsating pain or pain that comes and goes, which can be caused by muscle spasm, pain from a herniated disc is usually continuous or at least is continuous in a specific position of the body. Diagnosis is made by a practitioner based on the history, symptoms, and physical examination. At some point in the evaluation, tests may be performed to confirm or rule out other causes of symptoms such as spondylolisthesis, degeneration, tumors, metastases and space-occupying lesions, as well as to evaluate the efficacy of potential treatment options. The majority of herniated discs will heal themselves in about six weeks and do not require surgery. One study found that after 12 weeks, 73% of patients showed reasonable to major improvement without surgery. Surgery should only be considered as a last resort after all conservative treatments (non-surgical therapy) have been tried, that did not alleviate the pain and heal the disc herniation. Also, surgery is indicated if a patient has a significant neurological deficit. The presence of cauda equina syndrome (in which there is incontinence, weakness and genital numbness) is considered a medical emergency requiring immediate attention and possibly surgical decompression. [READ THE REST OF THIS ARTICLE]

The Leaning Tower of Pisa or simply the Tower of Pisa (Torre di Pisa) is the campanile, or freestanding bell tower, of the cathedral of the Italian city of Pisa. It is situated behind the Cathedral and is the third oldest structure in Pisa's Cathedral Square (Piazza del Duomo) after the Cathedral and the Baptistry. The height of the tower is 55.86 m from the ground on the low side and 56.70 m on the high side. The width of the walls at the base is 4.09 m and at the top 2.48 m. Its weight is estimated at 14,500 metric tons (16,000 short tons). The tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase. Prior to restoration work performed between 1990 and 2001, the tower leaned at an angle of 5.5 degrees, but the tower now leans at about 3.99 degrees. This means that the top of the tower is displaced horizontally 3.9 metres from where it would be if the structure were perfectly vertical. Construction of the tower occurred in three stages across 177 years. Work on the ground floor of the white marble campanile began on August 8, 1173, during a period of military success and prosperity. This ground floor is a blind arcade articulated by engaged columns with classical Corinthian capitals. The tower began to sink after construction had progressed to the second floor in 1178. This was due to a mere three-metre foundation, set in weak, unstable subsoil, a design that was flawed from the beginning. Construction was subsequently halted for almost a century, because the Republic of Pisa was almost continually engaged in battles with Genoa, Lucca and Florence. This allowed time for the underlying soil to settle. Otherwise, the tower would almost certainly have toppled. On January 7, 1990, after over two decades of stabilization studies, the tower was closed to the public. The bells were removed to relieve some weight, and cables were cinched around the third level and anchored several hundred meters away. Apartments and houses in the path of the tower were vacated for safety. The final solution to prevent the collapse of the tower was to slightly straighten the tower to a safer angle, by removing 38 cubic meters (50 cubic yards) of soil from underneath the raised end. The tower was straightened by 45 centimeters (18 inches), returning to its 1838 position. After a decade of corrective reconstruction and stabilization efforts, the tower was reopened to the public on December 15, 2001, and was declared stable for at least another 300 years. [READ THE REST OF THIS ARTICLE] is not affiliated with or endorsed by wikipedia. wikipedia and the wikipedia globe are registered trademarks of
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