Sea otters are a small mammal that lives in the waters along North America's west coast from California to Alaska. A few years ago some of the sea otter populations off of the Alaskan coast started to decline rapidly and raised several concerns because of their important role in the coastal ecosystem. Experts began investigating and came up with two possible explanations. One explanation was environmental pollution and the second was attacks by predators.
At first it seemed as if the pollution was the most likely cause for the population decline. One reason pollution was more likely was because of the known pollution sources along the Alaskan coast such as oil rigs. Also water samples taken in the area showed increased levels of chemicals that could decrease the otters' immune systems and indirectly result in their deaths.
Another thing that pointed to pollution as the culprit was the decline of other sea mammals such as seals in the same areas. This indicated that whatever was affecting the otters was also affecting the other sea mammals. Environmental pollution usually affects an entire ecosystem instead of just one species. Only predators that occurred in a large area, such as orcas (a large predatory whale), could cause the same effect, but they usually hunt larger prey.
Finally, scientists believed the pollution hypothesis would also explain the uneven pattern of otter decline. In some Alaskan locations the otter population declined greatly while other populations remained stable. Some experts suggested this could be explained by ocean currents, or other environmental factor, might have created uneven concentrations of pollutants along the coast.
In several organizations the best way to approach certain new projects is by establishing a team of individuals. There are several advantages to teamwork when completing a project.
One of the advantages of teamwork is the wider range of knowledge, skills, and expertise brought to the situation by having multiple individuals involved. Everyone is unique and has different skills, backgrounds and experiences. Therefore, others in a team can help an individual see things from a different angle.
Also, teamwork enables a group of individuals to respond more quickly to their assigned task and come up with creative solutions to problems. The projects will be completed more quickly because there are more resources in a group than an individual would have access to. Creative solutions are more likely to come about because teamwork spreads the responsibility for a decision to all of the members . This means that no single individual will feel as if they are solely responsible for a wrong decision.
Finally, being a member of a team can be very rewarding for the individual. Team members will understand the processes they are involved in instituting which will make them more comfortable with carrying out the work. In addition, individual team members have a better opportunity to get their contributions and ideas recognized as highly significant. This is because a team's overall results are likely to have a greater impact than would have been accomplished by an individual.
There are many paintings attributed to Rembrandt, the most famous seventeenth-century Dutch painter, but there are doubts that some of the paintings are truly by him. One such painting is "Portrait of an Elderly Woman in a White Bonnet" which was attributed to Rembrandt because of its style. The representation of the woman's face is very similar other portraits painted by Rembrandt, but there are problems that suggest it might not be a work by Rembrandt.
First, the clothing of the woman is inconsistent. She is wearing a white linen cap, like that of a servant, but her coat has a luxurious fur collar that would be worn by a wealthy member of society. Being known for his attention to detail, this is not something Rembrandt would have done.
Second, the lighting within the painting are not consistent with Rembrandt's style. He was known as the master of painting light and shadow, but in the painting light is reflected up onto the face, even though the collar below is a dark color which would have absorbed the light. Due to the darkness of the collar, the face should have been partially in shadow. Again this is not an error that Rembrandt would make.
Finally, the painting was revealed to have been painted on a panel of wood pieces glued together. Rembrandt often painted on wood panels, but he was not known to use more than one piece of wood. Due to these inconsistencies, the painting was removed from the official catalog of Rembrandt's paintings in the 1930s.
Endotherms are animals that maintain a constant body temperature no matter what the external temperature is. Humans are an example of an endotherm because they maintain a constant internal temperature of 37°C independent of external temperatures. Since modern reptiles are not endotherms, it is assumed that dinosaurs were not endotherms either because they are reptiles. However, dinosaurs were different in many ways from modern reptiles and there is considerable evidence that they were endotherms.
One piece of evidence is the existence of polar dinosaurs. Dinosaur fossils discovered in polar regions support the endotherm theory about dinosaurs because only animals capable of maintaining an internal temperature of the surrounding environment could be active in such a frigid climate.
A second piece of evidence is the connection between the position and movement of the legs and endothermy. The physiology of endothermy allows sustained physical activity. An example of these kinds of sustained physical activities is running. Running is only efficient if the animal's legs are positioned underneath its body like in all modern endotherms and in dinosaurs. This leg placement strongly suggests that dinosaurs were endotherms.
Finally, there is the connection between endothermy and bone structure. Canals that house nerves and blood vessels or rapid body growth called Haversian Canals are usually found in the bones of endotherms. The presence of these canals is a strong indication that the animal is an endotherm, and they have been found in the fossilized bones of dinosaurs.
The settlements of New Mexico's Chaco Canyon in American Southwest were notable for their massive stone buildings, known as great houses, containing hundreds of rooms and standing three or four stories high since the twelfth century A.D. Archeologists have been trying to determine how these buildings were used but still have not come up with a universally agreed upon explanation. However, there are three competing theories that provide plausible explanations.
One theory states the Chaco structures were residential and held hundreds of people. Supporters of this theory look to similar architectural structures in more recent Southwest societies. One structure, in particular, that is strikingly similar to the Chaco buildings is the apartment building at Taos, New Mexico, which has housed several people of the centuries.
The second theory argues that the Chaco structures were used as food storage facilities. Since one of the main crops of the Chaco people was grain maize, it could be stored for an extended time period without spoiling. The large size of the structures made them ideal for storing large crops of maize.
A third theory proposes the houses were used as ceremonial gathering places. Archeologists discovered a large mound of old material near one house called Pueblo Alto. Further inspection of the mound revealed deposits containing several broken pots. It has been documented in other Native American cultures that during special ceremonies they ate a festive meal and discarded the pots that the meal had been prepared or served with. Because of these documented ceremonies the finding at Pueblo Alto has been interpreted as evidence that people gathered there for special ceremonies.
One of the latest resources found on the internet is the communal online encyclopedia. These encyclopedias are, in many ways, like the traditional printed encyclopedias containing collections of articles on various subjects. The unique feature of the online encyclopedias is that any internet user can add a new article or make an editorial change to an existing one. This results in an encyclopedia authored by the entire internet community. While this sounds like a good idea, communal encyclopedias have several important issues that make them less reliable than the traditional printed encyclopedia.
First, the contributors from the online community often lack academic credentials resulting in partially informed or inaccurate information. On the other hand, traditional encyclopedias are written by trained experts following a rigorous academic standard that non-specialists cannot really achieve.
Second, the communal nature of these online encyclopedias provide the opportunity for dishonest individuals to fabricate, delete, and corrupt information in the encyclopedia. After the changes are made it is impossible to tell the entry was tampered with. This isn't possible with traditional encyclopedias.
Finally, the communal encyclopedias focus more frequently on popular topics giving them the appearance of equal importance to an important historical event. This can give someone like a child doing a research project for school the misconception of how important a topic truly is. In a traditional encyclopedia, there is a considered view of what topics should be included or excluded and a sense of proportion not found in communal encyclopedias.
An international organization has started issuing certifications to wood companies who meet a high ecological standard by conserving resources and recycling materials in an effort to encourage ecological sustainable forestry practices. Certified companies can attract customers by advertising their products as eco-certified. Many wood companies around the world have adopted eco-friendly practices in order to receive the eco-certification; however, it is unlikely that United States's wood companies will do the same for several reasons.
First, due to the high levels of advertising American consumers are exposed to they would not pay attention to the eco-certification label. Americans have lost their trust in advertising claims because of how many mediocre products have been labeled as new or improved.
Second, the costs a wood company pays to have their business examined by a certification agency will drive the prices higher than uncertified wood. The American consumer is typically motivated by price and they are more likely to purchase the cheaper, uncertified, wood product instead. Therefore, American companies would prefer to keep their prices low instead of obtaining eco-certification.
Third, the claim that it always makes good business sense for American companies to keep up with the rest of the world's developments is not a convincing argument. If American wood companies marketed to a global client base it would be reasonable to argue for the eco-certification, but that is not the case. Most of the American wood business' products are sold in the United States and has a very large customer base that is satisfied with their products.
Chevalier de Seingalt (1725–1798) recounted his life and adventures in a long memoir written toward the end of his life. the Chevalier was a controversial figure, but because of the people he met, his memoir became a valuable historical source about eighteenth century European society. However, the accuracy of the memoir has been brought into question by critics claiming that the Chevalier distorted or invented events to make his life seem more glamorous than it was.
One point brought into question was that, in his memoir, he Chevalier claims he was very wealthy while living in Switzerland. While it was known he spent large amounts of money on parties and gambling there, evidence has recently surfaced showing that the Chevalier borrowed large sums from a Swiss merchant. Critics argue that because of his need for borrowing money he could not have really been very rich.
Critics also question the accuracy of the conversations the Chevalier records in his memoir between himself and the famous writer Voltaire. There is no doubt that these two men met and conversed; however, critics state that it is impossible for the conversations to accurately be captured because they were recorded many years after they occurred. Critics point out that exact phrases from the extended conversation held years before are impossible to remember.
Another disputed event is the Chevalier's account of his escape from a notorious prison in Venice, Italy. The Chevalier claims he used a piece of metal to make a hole in the ceiling and climb out of his cell. Critics argue that, while it makes for an enjoyable reading, it is more likely that the jailers were bribed to free him. They note that the Chevalier had many politically well-connected friends in Venice capable of offering a bribe.
Car manufacturers and governments have eagerly been seeking a replacement for the internal combustion engine as an automobile's main source of power. The most promising alternative source is currently the hydrogen-based fuel-cell engine which uses electricity created by hydrogen to power the car. There are several advantages to fuel-cell engines over the internal-combustion engine and will probably replace them soon.
The main problem with internal-combustion engines is that they rely on petroleum. Petroleum is a finite resource. At some point in the future, the supply of oil in the Earth's crust will be exhausted. On the other hand, fuel-cell engines use hydrogen fuel for motive power. Hydrogen cannot easily be depleted and is found in various plentiful resources including natural gas and water. This makes hydrogen fuel cells a better environmentally-friendly alternative to conventional fossil fuels.
Also, fuel-cell engines are particularly attractive as an alternative power source for cars because they will solve several of the world's pollution problems. By oxidising molecular hydrogen, the only direct by-product of their energy generation is water, which means they could significantly reduce pollution and man-made greenhouse gases. On the other hand, carbon monoxide, nitrogen oxides, and hydrocarbons are released when fuel is burned in an internal combustion engine.
Finally, fuel-cell engines will become economically competitive due to the reduced cost of operating them. A fuel-cell automobile is almost twice as efficient at fuel use as an internal-combustion automobile. This means that it only requires half of the fuel energy to go the same distance as an internal-combustion powered car.
Employees in the United States typically work five eight-hour days per week; however, many employees would prefer to work four days per week and are willing to accept less pay in order to do so.
Creating a mandatory policy requiring companies to offer their employees the option of a four-day workweek at 80 percent of their normal pay would benefit the economy, the individual companies and their employees who take the option. The shortened workweek would increase company profits because employees would feel more rested and alert resulting in fewer costly errors in their work. Hiring more staff to ensure the same amount of work would be accomplished would not result in additional payroll costs because four-day employees would only be paid 80 percent of their normal rate. In the end, companies would have fewer overworked and error-prone employees for the same money, and would increase company profits.
The primary benefit to the economy by offering this option would be a reduction in unemployment rates. If several full-time employees started working fewer hours, employers would have to shift some of their workload to another employee. For every four employees who worked an 80 percent week, a new employee could be hired at the 80 percent rate to pick up the extra work created by the shorter week of the other employees.
Finally, a four-day workweek would improve the quality of life for the individual employees who could afford a lower salary. By reducing their hours at work, employees would have the ability to spend more time with their families, pursue private interests, or enjoy leisure activities.
Over time partially decayed vegetation or organic matter can develop a natural area called a peat land or mire. The layers of decayed vegetation or organic matter create a type of turf called peat. The ecosystem created in these peat lands is the most efficient carbon sink on the planet because the peat land plants capture the CO2 (carbon dioxide) that is naturally released from the peat to maintain the equilibrium in the environment. However, there have been plans to build wind turbines in the peat lands of Scotland. A wind turbine is a device that converts the kinetic energy produced by the wind into electrical power. While this would be ecologically beneficial to create power, it would be harmful to the Scotsman's economy and to the peat lands.
First of all, building turbines in the peat lands of Scotland would hurt the local tourism industry which is recognized as a key contributor to the Scottish community. The Scottish Parliament Information Centre (SPICe) published a briefing in 2002 for the Scottish Parliament's Enterprise and Life Long Learning Committee stating that tourism accounted for up to 5% of GDP and 7.5% of employment. The destruction caused in the peat lands would also hurt production of certain Scotch whisky distilleries who use peat fires to dry the malted barley giving their whiskies a distinctive smoky flavor called "peatiness".
Also, the release of the buried greenhouse gases that would occur in the process of demolishing the peat lands would be more environmentally unfriendly than the current methods used to produce electricity. This is because of the high concentration of CO2 captured by the plants in the peat lands.
Finally, there are alternative options that would spare the peat lands in Scotland such as building offshore in a shallow sea area. Building in this alternative location, many species of fauna and flora specific to peat wetland environments would be protected. It takes centuries for a peat box to recover from being disturbed so any destruction would be felt for a long time.
The post-Republican period of the ancient Roman civilization, known as the Roman Empire, was characterized by a government headed by emperors and large territorial holding around the Mediterranean Sea in Europe, Asia, and Africa. The Roman Empire was the largest empire of the Classical Antiquity period, and one of the largest in world history covering 6.8 million square kilometers. It was also among the most powerful economic, cultural, political and military forces in the world holding sway over 21% of the world's entire population during that time period. The longevity and vast reach of the Empire provided a lasting influence of Latin and Greek language, culture, religion, inventions, architecture, philosophy, law, and government on future descendants. There are three reasons the Roman Empire became so powerful.
The first reason was their large armies that occupied the lands of other countries. These armies were made up of captives forced to serve in the army and by the professional soldiers of the Imperial Roman army. Professional soldiers volunteered for 20 years of active service followed by five years of reserve duty. This was a definite shift from the material of the former republic in which an army of conscripts exercised their responsibilities as citizen to protect their homeland in specific campaigns against specific threats, whereas Imperial Rome's army was a full-time career.
The second reason for the Roman Empire's rise to power was the power held by the monarchs. This state of the absolute monarchy began with Diocletian and endured until the fall of the Western Roman Empire in 476 CE. The authority of the emperor was based on the consolidation of several of the republican offices. The emperor had powers of inviolability of the tribunes of the people, authority of the censors to manipulate the hierarchy of Roman society, central religious authority as Pontifex Maximus, the right to declare war, ratify treaties, and negotiate with foreign leaders. These functions were clearly defined during the Principate, but over time the emperor's powers became less constitutional and more monarchical creating the dominate.
Finally, the high taxes placed on their empire helped to make the empire richer. The taxes an individual paid ranged from 2 to 5 percent of the gross product. The bewildering tax code involved a complicated system of direct and indirect taxes as well as taxes paid in cash and some paid in kind. The taxes might be specific to a province, property, or in effect for a limited time. The Roman Empire justified their tax collection as a necessary cost to maintain the military; however, taxpayers sometimes received a refund if the army obtained a surplus of booty. Less monetized areas that were unable to pay their taxes in cash were allowed to pay in-kind especially if they could supply grain of goods to the army camps.
Antlers are extensions of the skull grown by members of the deer and antelope family. They are bone structures usually found in symmetrical pairs and, in most species, are only grown by the males of the species. Antlers have several functions such as fighting or attracting females. The following are three of the functions of antlers.
First, antlers can help with heat dissipation. The horns have been shown to contain vascular tissue and the large surface area of the antlers versus the amount of blood flowing through the tissues allows for the blood to cool before returning to the rest of the body.
Second, antlers are used as a defense against predators. Antlers are used in male-male fights it stands to reason that they would use them to defend against other threats. When cornered by a predator and forced to fight, the antlered animal can use them to fend off the attacking animal.
Finally, they are used to display their strength and fertility to the female members of their species and to compete with other males. Larger antlers mean that the male is strong and most likely very fertile. They are also used to compete against other males in displays of strength to win the females.
Lake Powell is a reservoir on the Colorado River that straddles the border between Utah and Arizona, and it is the second largest man-made reservoir in terms of maximum capacity storing 24,322,000 acre feet of water when full. Lake Powell was created by the flooding of Glen Canyon by the Glen Canyon Dam, which also led to the creation of Glen Canyon National Recreation Area, and is a popular summer destination that approximately 2 million people visit every year. The lake is an important resource for the economy of local towns and the environment. This is just the first of many reasons Lake Powell should not be drained.
The lake is a tourist attraction that allows visitors to go boating in the water and is a substantial source of revenue. Glen Canyon National Recreation Area was established in 1972 on public land and is managed by the National Park Service. If the lake was drained it would damage the revenue of the surrounding area.
Lake Powell also supplies water for the surrounding area and is the largest reservoir in terms of the amount of water currently held, depth, and surface area. It is a water storage facility for the Upper Basin states of the Colorado River Compact (Colorado, Utah, Wyoming, and New Mexico), and regulations within the Compact specify that the Upper Basin states are required to provide a minimum annual flow of 7,500,000 acre-feet to the Lower Basin states (Arizona, Nevada, and California).
There are also several fish species that reside in the lake including some species that are on the US Endangered Species List. Currently most of the native species on the Colorado River Basin are part of ongoing restoration efforts and the influx of bass if Lake Powell were to be drained could interfere with these efforts.
A menhaden, also known as a mossbunker, bunker, and pogy, is any forage fish of the genera Brevoortia and Ethmidum of the family Clupeidae. Gulf menhaden and Atlantic menhaden are small oily-fleshed fish characterized by their bright silver color and a series of smaller spots behind the humeral spot. They are flat with soft flesh and a deeply forked tail, and they grow to a maximum of 15 inches long. According to the Atlantic States Marine Fisheries Commission, the stock of menhaden is not considered overfished currently, there have been 32 instances of overfishing in the past 54 years. Paul Greenburg, the author of Four Fish: The Future of the Last Wild Food, has called for a fishing ban for menhaden in US federal waters and the Chesapeake bay due to the detrimental effects overfishing is having on the population, and in turn the menhaden's predator populations and the water quality. However, a fishing ban is not the best course of action.
One factor that could be resulting in the reduced population of menhaden is the large population of striped bass. They are a culprit in the decline of the menhaden population because as their population grows they eat more fish including menhaden. This type of culprit would not be effected by placing restrictions on menhaden fishing.
Also, because menhaden are a food source for all animals, the prohibition of fishing menhaden would break a supply chain. Therefore by trying to protect menhaden through the prohibition of fishing it is really hurting the food supply for others.
Finally, if the government were to issue these harsh fishing restrictions, a lot of people would become unemployed. Those who depend on fishing menhaden for a living would not be able to maintain their livelihood if they are no longer able to fish for them.
A bust is a sculpted or cast representation of the upper part of the human figure normally supported by a plinth. These forms are in likeness to an individual and can be created from any medium such as marble, bronze, terracotta, or wood. One such bust found in a river in France is considered to be the 50-year-old self-statue of Julius Caesar based on the following three reasons.
First, the style of the bust found in the river was realism, a style of art attempting to represent subject matter truthfully, which was a prevalent art style of the time. This lines up with the time period that the statue is believed to have been created in.
Second, the bust resembles other works of Julius Caesar. The hair line is very similar to that of the image on coins depicting him. Because of the resemblance between known images of Julius Caesar it is probably his 50-year-old self-statue.
And finally, people of this time period often buried this bust in order to show reverence for Julius Caesar. This was due to the unfortunate circumstances of his demise and how many people had respected him as a political official.
Glass is one of the most popular materials for modern architecture. However it is also very dangerous for wild birds because it is difficult for them to distinguish the difference between open air and glass. As a result, millions of birds are harmed every year when they fly through glass windows. But there are a number of solutions that can be used to prevent injuries to birds from the businesses that are housed in those modern glass buildings.
The first solution is to replace the regular, clear glass with one-way glass that is transparent in only one direction. This ensures that the occupants can still see out of the building, but the birds cannot see in. Of course, if birds cannot see through a window, then they understand that the glass forms a solid barrier and won’t try to fly through it.
Another solution is to use colorful lines or designs on glass windows. If a window had thin stripes or a decorative pattern over the glass, the birds would actually avoid trying to fly through the glass. Meanwhile people would still be able to see through the windows, in the places the paint is not covering the windows. Architects can be encouraged to include colorful painted patterns on glass as part of the general design of buildings.
A third solution is by using a magnetic field. You can use an artificial magnetic field to guide birds away from buildings. A magnetic compass is an instrument that humans use to determine directions, such as north, west, east, or south. Bird research has shown that birds have a natural ability to sense Earth's magnetic fields. This ability is similar to a compass. It helps birds with their sense of direction. They have the ability to navigate in the correct direction when they fly. If there is a building in the path of a bird’s flight, that building can be equipped with powerful electromagnets that emit magnetic signals that steer birds in a direction away from the building.
Folic acid, or folate, is one of 12 B vitamins and is especially important to women who are pregnant or attempting to become pregnant. It has been shown that adequate folate ingestion during the preconception period helps protect against several congenital malformations such as neural tube defects. Neural tube defects are severe abnormalities of the central nervous system that develops in the first few weeks of embryo development and can result in malformations of the spine, skull, and brain. The most common neural tube defects are spina bifida and anencephaly. Because of this risk to the health of the embryo, pregnant women especially need proper amounts of folic acid and as a result it has been proposed that folic acid should be added to bread and other flour products to avoid this problem. However there are problems that could arise from this measure and it would not solve all of the current problems.
First, even if the folic acid was added to items like bread, women, even a young woman, would not be able to receive an adequate amount of it through a typical diet. The amount of folic acid women would receive would vary greatly depending on the type of diet they maintained. This method would not be a reliable way to solve the problem of pregnant women not receiving adequate amounts of it early in the pregnancy.
Also, by adding extra things to food, it can have adverse effects on the elderly. The addition of folic acid to everyday foods could be dangerous to the elderly community because they generally take supplements that add 400 micrograms (μg) to their daily folic acid intake. Adding folic acid to their daily food would increase this amount to more dangerous levels causing them to have higher levels of unmetabolized folic acid which can accelerate the growth of preneoplastic lesions.
And finally, tablets that add folic acid to the diet of pregnant women are readily available. The levels of folic acid in these tablets are only suitable for pregnant women and guarantee they receive the proper amount when used.
New Zealand, located in the southwestern Pacific Ocean, is an island country that geographically comprises two main landmasses, North Island (Te Ika-a-Māui) and South Island (Te Waipounamu), and several smaller islands. There is evidence that the first inhabitants of New Zealand moved there around 1300 C.E.
One piece of evidence is the indigenous Polynesion people of New Zealand, the Māori, who originated from settlers arriving in waves of canoe voyages from eastern Polynesia. Over several centuries of isolation on the islands, the Polynesian settlers developed their own culture that would become known as the Māori. They formed their own language, rich mythology, and distinctive crafts and performing arts. Historically the Māori contains 24-27 generations. If each generation averaged approximately 25 years apart then by calculating the number of years multiplied by the number of generation the Māori moved to New Zealand around 1300 C.E.
Also, a pollen study shows that trees were replaced by the grass around this time period which would not be caused by forest fires. Therefore it is concluded that it was a result of primitive agriculture and must be of human origin.
Finally, artifact have been dated using radiocarbon dating and show evidence of human occupation from around 1288 C.E. to 1300 C.E. Radiocarbon dating determines the age of an object by using the properties of radiocarbon, a radioactive isotope of carbon, to determine how old an object is depending on how much radiocarbon is still present. By using this process, scientists are able to give an estimate of when something originally existed.
Wildlife crossings are structures built to allow animals to cross human-made barriers safely. These crossings promote habitat conservation by allowing connections and reconnections between habitats to avoid habitat fragmentation. They also lower instances of collisions between animals and vehicles that cause injury, and sometimes death, to both wildlife and humans. While the conservation benefits created by these structures are a priority of several groups, they are not as useful as they seem.
First of all, animals cannot train themselves to use crossings like we do. If the animals cannot make use of the crossings, the crossings are considered useless. Also, research suggests that animals living in the wild are often reluctant to cross these crossings to mingle with other populations.
Secondly, because the crossings are useless, they become a waste of financial resources. Wildlife crossing includes structures such as underpass tunnels, viaducts, overpasses, amphibian tunnels, fish ladders, and green roofs. Each of these structures requires money to build, but because of the uselessness of the structures they become just another financial waste for the country building them.
And finally, the developed areas that create the wildlife crossings are damaged and prevent wild animals from reproducing. While loss of habitat, road kill, and isolation from resources exert pressure on various animal populations by reducing available resources and killing individuals in the populations, Bennet (1991) found that road kills do not pose a significant threat to healthy populations and are only devastating to threatened populations.
Mima mounds are low, flattened, domelike mounds composed of loose unstratified sediment as a over-thickened top soil (A Horizon). These mounds come in many sizes of mound and groups of mounds. There are three theories on how Mima mounds originated.
The first theory is that they are made by Native Americans. There have been records of similar structures being created by Native Americans during burial rites. Because of the similarities in the structure it was concluded that the Mima mounds were made by Native Americans.
A second theory is they were created by a major earthquake. Seismic activity generates vibrations through the earth that can move sediment and loose soil. This is concluded based on the loose structure of the soil in the Mima mounds.
Finally, the third theory is that they were created by pocket gophers. More commonly referred to as gophers, they are burrowing rodents of the family Geomyidae. A reason that these creatures, who live mostly underground, would create these large mounds of earth in nutrient poor landscapes would be to provide a place for them to go when it rains. This way they are above the water line and can receive plenty of oxygen.
Blood rain, or red rain, is a phenomenon in which blood appears to fall from the sky as rain. A recent occurrence of this was in Kerala, India, where blood rain fell for two months in 2001. up until the 17th century it was generally believed that red rain was actually blood and was a bad sign. In the 19th century scientific explanations were being explored. Three explanations for blood rain have emerged.
The first explanation is that ash from a volcano was blasted into the atmosphere and caused the rain to be red. This theory states that volcanic ash stays in the atmosphere for up to hundreds of miles before falling to the ground in rain. Because of the composition of the ash, the rain is stained red.
Another explanation is the sediments creating the red color were there as a result of a meteor explosion. Inhabitants of Kerala reported a bright flash of light and "thunder" like nothing they had ever heard. The meteor explosion would have produced the light, thunder, and enough matter to create the red rain.
And finally, lichen spores that are released into the air could fall as red rain. Spores are a common reproductive function of lichen fungi . If a dense area of lichens were releasing spores at the same time, then it would gather in the atmosphere and create red rain.
The Ordovician period is a geologic period that occurred around 440-485 million years ago and lasted for approximately 45 million years. During this time period the oceans teemed with life. Life on land was still in the early stages of diversification. This period came to an end after a series of extinction events that created the second largest major extinction in Earth's history. There are several possible explanations for the cause of the mass extinction of marine life at the end of the Ordovician period. The following three reasons are the most likely.
First, when the climate cooled significantly ice sheets formed causing the sea level to drop by as much as 100m. This destroyed the habitat of species living in the shallow oceans. It also spelled disaster for species that were adapted to warmer waters and could not survive the cooler conditions that created the ice sheets.
A second theory is that the impact from a meteorite caused the mass extinction. The dust created from such an impact would be enough to completely block out the sun. Since many organisms, especially those near the ocean surface, relied on sunlight as part of their survival then the complete blocking of the sun would be devastating to these creatures.
The third theory is super UV rays. This theory states the sun's ultraviolet rays were very strong and killed marine organisms living in the ocean surface. Fossils found showing the disappearance of one kind of marine life in the ocean surface provide evidence for this theory.
North America is a continent that is completely within the Northern Hemisphere and almost entirely in the Western Hemisphere. It is the third largest continent and has the fourth largest population in the world. It was previously thought that the first people to reach North America were Asians, but new evidence has shown that they were actually Europeans.
First, scientists found spear points of similar shape and style in both Europe and North America. These spear points were large and fashioned like a sharp blade. In contrast, the spear points found in Asia are very small and don't share many similarities.
Also, European bones have been found that can prove the earliest people were European. Bones analyzed from a 24,700 year old skeleton of a child have provided DNA that was able to be extracted showing genes found primarily in European humans.
Finally Europeans could have crossed the Atlantic Ocean while it was covered in ice during the ice age. An ice pack stretched from France to North America during the glacial maximum. This provided the opportunity for them to travel similarly to the Inuit tribes of Alaska. They could haul their boats onto the ice at nights to rest and hunt seals and other ocean dwelling creatures for food and warmth.
The coal industry has had a large environmental impact from land use, waste management, water and air pollution caused by coal mining, processing, and using coal. Not only does it cause atmospheric pollution, but coal burning also produces millions of tons of solid waste products. Burning coal comes with severe health effects and is estimated to shorten approximately 1,000,000 lives worldwide every year. The following are three methods for reducing the pollution produced by coal burning.
One method is to improve the reaction efficiency. By improving the reaction efficiency, air pollution can be reduced. It will not be an immediate impact, but over the long term it will have a significant impact.
Another method is to use water to flush the coal and remove sulfides to prevent the creation of sulfur dioxide. This would help to reduce the level of pollution created by the sulfides reacting with the air.
A third method is to collect the emitted carbon dioxide. This would prevent the gases from reaching the atmosphere. Pollution levels from carbon dioxide would drop significantly over time as this technology is expanded.
Diprotodon is the largest known marsupial to have ever lived. It was a member of a group of unusual species known as the "Australian megafauna" and existed around 1.6 million years ago. The largest specimens discovered were as large as a current-day hippopotamus. There are many conflicting theories about when the diprotodon became extinct, these times range from 28,000 to 46,000 years ago. There have been three theories suggested for the mass extinction of the species.
The first theory is that fire set by humans caused them to become extinct. It is believed that early Aborigines would use fire to manage the land and drive game. This could have caused the diprotodon to lose its home and environment. With less land to have a natural environment undisturbed by humans, there was less room for them to live.
A second theory is that they were hunted to extinction by humans. Fossils found with what appear to be butchering marks support this theory. Other support for the theory comes from other places where overhunting led to the extinction of megafauna such as in New Zealand and Madagascar.
Finally, the third theory for the extinction of the diprotodon was a cold and dry climate. Around the proposed times of the extinction of the diprotodon was when an ice age was occurring. An ice age is a long period of reduction in the temperature of the Earth's surface and atmosphere, resulting in the expansion of ice sheets and glaciers. It is possible that diprotodon went extinct because of the temperature drop during the ice age.
Torreya taxifolia, once a very common evergreen tree in the state of Florida started to die out in the 1950s. If nothing is done soon, there is a possibility that Torreya could become extinct altogether because no one knows exactly what caused the trees to die out. In order to save Torreya from extinction, experts are considering three solutions.
The first solution is to reestablish Torreya in the same location in which it thrived for thousands of years. Torreya used to be found in abundance in the northern part of Florida, which has a specific microclimate. When weather conditions inside a small area are different from the region it is a part of, then a microclimate exists. Northern Florida's microclimate is very favorable to Torreya's growth because it is cooler and wetter. Meanwhile the surrounding region has a very warm and dry climate. Scientists have been working to plant Torreya seeds in the dampest and coolest areas of the microclimate.
A second solution is to move Torreya far from its microclimate in Florida. Possibly move it to an entirely different location. In fact Torreya seeds and saplings have been successfully planted and grown in forests further north, where the temperature is significantly cooler. Some scientists believe that Torreya probably thrived in areas much further north in the distant past. They can use a process called assisted migration to help relocate the special evergreen trees. Humans would simply be helping Torreya return to an environment that is more suited to its survival.
The third solution is preserving Torreya in research centers. Seeds and saplings can be moved from the wild and preserved in a closely monitored environment where it will be easier for scientists both to protect the species and conduct research on Torreya. The research done in these centers can then be used to ensure the continued survival of the species, as well as, help to understand the factors that caused them to die out.
Dinosaurs are a diverse group of animals of the clade Dinosauria that first appeared during the Triassic period approximately 231.4 million years ago. They were the dominant terrestrial vertebrates for 135 million years. Many dinosaurs had crests and frills such as the marginocephalians, theropods, and lambeosaurines. The crests found on these different species were too fragile to be used as physical defense. Therefore, there must have been some other use for the crests. There have been three different hypotheses for the use of the crests.
One hypothesis is that the crest was used to enhance the dinosaur's sense of smell. The crest was believed to expand the surface area of smell sensory receptors. Providing more receptors meant that more smells could be picked up and identified.
Another hypothesis was that the crest was used to help cool the dinosaurs. The dinosaur's crest would increase the surface area of their skin surface. This would allow for the dinosaur to catch more of the breeze and utilize it to keep them cool during hot times of the year.
And the third hypothesis was that it was used to phonate. Dinosaurs would use their crests to amplify sounds to communicate with other members of their herd. This would allow the dinosaurs to communicate over greater distances.
Ansel Easton Adams (Feb. 1902–Apr. 1984), and American photographer and environmentalist, has had his black-and-white landscape photographs of the American West widely reproduced on calendars, posters, and in books. Adams, with Fred Archer, developed the Zone System to determine proper exposure and to adjust the contrast of the final print in a photograph. His works held such clarity and depth that they became the foremost record of what National Parks were like before tourism. In California, envelopes containing photographic negatives considered to be made by Ansel Adams was found at a sale. There are several factors that make experts believe that the negatives are the work of Adams.
One factor pointing to the photographs being works by Adams is a photographic negative of pine trees leaning downward on a cliff. This same image is seen in other well known photographs of Adams.
Also, the handwriting of the address on the envelope looked very similar to that of Virginia Adams, Ansel Eaton Adams' wife, who acted as his assistant. It is very likely that Adams created the negatives and Virginia Adams organized them. This would explain the similar handwriting.
And finally, some of the negative appear to have fire damage. It is known that Adams' studio has caught on fire before. A third of his negatives were burned in that fire so some evidence of fire damage would be expected on surviving negatives.
Repenomamus robustus was not an active hunter of dinosaurs. Repenomamus was a mammal in the early Cretaceous period and its fossils were found in the lagerstätte of the Yixian Formation in the Liaoning province of China. There are three reasons that Repenomamus robustus is not believed to be a predator of dinosaurs.
First, Repenomamus robustus was only about the size of a domestic cat. This small size would have made it nearly impossible for it to actually attack and kill the dinosaurs of this time period who were much larger such as psittacosaurs. Psittacosaurs were almost two meters tall when full grown. Given this size difference, it is unlikely that Repenomamus robustus would have been able to successfully hunt psittacosaurs.
Second, the Repenomamus robustus had legs that were not very well structured for running quickly. Their legs were short. This would have made them too slow to catch dinosaurs when they were running. The leg placement was also not suitable for hunting. Rather than directly underneath the animal, their legs were positioned to the side. Psittacosaurs—the type of dinosaur found in the stomach of R. robustus—were fast moving. It is unlikely that they would have been caught by Repenomamus robustus.
Finally, although there have been dinosaur bones found in the fossilized remains of Repenomamus robustus stomachs, they lack teeth marks on the bones themselves. This lack of teeth marks makes it unlikely that they were eaten by it. Most bones when eaten by other creatures have some evidence of having been bitten before swallowing.
Many people have heard of the Great Depression, but what caused this economic downturn? One of the great signifiers of the beginning was the Stock Market Crash of 1929. With that came the disaster of thousands of banks collapsing through the 1930’s. With the failure of financial institutions came a reduction in personal spending. These three factors helped bring about this awful disaster.
In the beginning came Black Tuesday 1929. That day the value of shares in the Stock Market plummeted, causing people to lose fortunes. Within two months shareholders lost nearly 40 billion dollars. With no end in sight the country braced itself for the eventual repercussions of major companies and wealthy citizens losing so much capital in such a short time.
Following the market crash came trickling effects of this disaster. Throughout the 1930’s, 9,000 banks failed. This means that any bank that overstretched itself through loans could declare bankruptcy. Any person with funds in that bank would simply lose their entire life savings. Also, people stopped investing their money in banks, and banks stopped offering loans creating a series of continued problems.
A final cause came because of this lack of personal and commercial investment. Whether because of a loss of personal finances or a lack of commercial options, people stopped buying things. Without money to buy things the market continued its downward spiral, bringing banks and personal finances with it. This lack of personal spending perpetuated the problem of dwindling market values.
In the end the causes of the Great Depression were byproducts of each other. Starting with problems of an overextended market that crashed and died quickly over a few months, the spiral began. From there the failure of banks coupled with a lack of purchasing destroyed exchanging finances. Thus the United States created and endured the greatest financial disaster of the world.
There are creatures that utilize a unique biological function known as bioluminescence, or glowing in the dark. They have the ability to illuminate their bodies. Some scientists believe they use this feature to communicate. However, others believe it’s being used for hunting and attracting prey. Finally other scientists believe creatures use bioluminescence for camouflage and defense. Despite the theories, many mysteries exist concerning bioluminescence.
The first feature scientists noticed for bioluminescence is communication. Certain animals such as fireflies use colors and patterns to communicate with each other. By using light to communicate these animals express themselves over long distances in complete silence. Many believe that when animals use bioluminescence for communication the primary use is for mating. The light works the same way that bird plumage or animal calls attract mates.
On a different note, some animals use bioluminescence for hunting. Some animals use the light the way people use night vision goggles or flashlights. The light allows creatures to see in dark areas and hunt. Some animals use bioluminescence as an attraction to draw animals closer. Attracted by the light, some animals become easy prey for bioluminescent animals.
A complimentary idea to bioluminescence for hunting is for defense. Certain fish have been able to generate light to their advantage by glowing to blur their outline and make them a harder target for prey. Other animals release glowing light as an inky residue when they are attacked to distract their predator while they escape. Thus they use bioluminescence for defense.
All in all, the role of bioluminescence is more varied than other biological functions. Through this act of glowing, creatures communicate their needs and desires. Other animals are capable of hunting with greater ease, while others use their glowing as a means of defense and camouflage. Through tracking these varying uses scientists have been able to gain greater understanding of bioluminescence.
Despite the obvious advantages of technology, social media has generated highly negative consequences. To begin with, social media has created a false sense of connectivity and friendship. Additionally, social media has encouraged new forms of harassment through cyber-bullying. One last result of social media is a decrease in overall productivity. These negative attributes make social media a dangerous and controversial set of tools.
The first negative consequence of social media is a false sense of connectedness. People feel a sense of belonging when they can log onto the Internet and see the people they can talk to. Unfortunately, despite the number of people everyone can connect with, there are lower standards for what constitutes a friend. Relationships are casual online interactions rather than legitimate friendships.
Another consequence of social media is the creation of cyber-bullying. People in all age groups now find themselves the object of scorn and derision through message boards. In online interactions, people don’t fear to say things because they don’t have to do so in person. This unfortunate byproduct can have dreadful repercussions for both bullies and the bullied.
Finally, social media has become a distraction and decreased productivity. Students doing homework are likely to be pulled towards scouring social media to check on their friends. Rather than pursuing hobbies, people are more likely to spend time pursuing artificial relationships they established online. Social media has ultimately provided a source of addicting distraction that has turned the world into unproductive workers.
Thus when all factors are considered, the presence of social media has simply brought about too many negative repercussions for people. It has replaced genuine relationships with impersonal interactions. It has introduced a new and almost unpunishable form of bullying. Also, it has become a distraction, turning people into unproductive workers. The snowball effect of negative repercussions is astounding when examined in unison.
Despite the wonder of nuclear energy, there remain too many disadvantages to utilizing it. First, the waste produced through nuclear energy offsets the benefits. Secondly, manufacturing comes at a high price to the health of the entire planet. Finally, the high cost of manufacturing and continual production is not feasible within most economies. These various disadvantages weigh heavily against an argument for nuclear energy.
A concern for nuclear energy is disposing of hazardous waste. Nuclear energy produces millions of gallons of radioactive waste that needs to be disposed of properly. This waste, if leached into ground water, the air, or people’s yards, can have deadly consequences for all creatures. So not only is the waste itself an issue, but the disposal of that waste has further disadvantages.
As a consequence of radioactive waste, we should be concerned about the biological consequences. In our time of nuclear energy production, there have been numerous nuclear catastrophes. Some were small-scale and others were large disasters. Even with minimal exposure, nuclear radiation and waste can cause vomiting, diarrhea, or cancer. Major problems take centuries to clean up during which people lose their homes, their health, and their livelihood.
A final disadvantage to nuclear energy is the high cost. On top of the initial cost, nuclear energy reactors also require immense legal fees. Also, construction can take up to a decade, which further complicates the process costs. An additional cost is the uranium needed for a nuclear reaction. This is far beyond the power of most countries or investors to acquire.
Nuclear energy, therefore, has many disadvantages. In the process of creating energy, radioactive waste is created and must be disposed of properly. When not created safely, or when waste is not disposed of properly, nuclear energy poses an immense danger to the planet. The cost of production and safety is too high anyway. Overall, nuclear energy should not be an option for energy production.
During early human history, nomadic hunters dwelled in caves where they painted magnificent works of art. Various theories have circulated beginning with the idea of paintings as hunting magic. Another theory considered the paintings as decorative religious spaces. A final theory proposed that the paintings were part of a worldview known as shamanism. Each of these theories attempted to systematically study and interpret the paintings.
One reason offered for ancient cave paintings is called the sympathetic magic theory. Within this concept, archaeologists explain the existence of the paintings as hunters’ wishful thinking. In their time between hunts, cave dwellers would paint images depicting great hunts. The paintings depicted animals being defeated, hoping to magically inspire a future hunt. This makes sense knowing that hunters’ lives relied on a successful hunt.
However a second answer to cave paintings existence attributes the paintings to religious spaces. Given the consistency of the paintings, some scholars believe they reflect modern religious sites. Also, some of the areas painted were not easily accessible, requiring some serous motivation for painting. The scale of such project does seem to align with the zealous approach of religious design and construction throughout human history.
Lastly, is a similar religious approach through the lens of shamanism. Shamanism believes there are multiple worlds existing and influencing each other. Some paintings have a mythical look where human and animal forms are mixed, mysterious symbols are used, and godly acts take place. Scientists speculated that cave dwellers believed in extreme interactions with the supernatural. Given these unnatural depictions this theory holds great weight.
In the end there are some strong theories explaining the ancient cave paintings. Some believe they exist as a magical attempt at conjuring amazing hunts. Others think the spaces were for religious ceremonies. Others believe the ancient cave dwellers were shamanistic and believed in the supernatural. Despite their differences, all these theories celebrate the magic and mystery of the world’s ancient ancestors.
Although it’s a new technology, solar energy provides benefits to the entire world. First, solar energy eliminates our reliance on non-renewable fossil fuels. Additionally, solar energy is non-pollutant, which makes it better for everyone. Finally, there is almost no maintenance as solar panels have a long life span without regular maintenance. So, the benefits seem to be overwhelmingly positive and supportive of further production.
The first benefit is the ability for solar energy to reduce reliance on fossil fuels. Many sources of energy are renewable only over millions of years. Unfortunately, humans consume those faster than they are produced. Solar energy could be a replacement for non-renewable sources as a perpetual source of energy. Thus solar energy can become a new energy with no legitimate fear of overproduction.
Another benefit is the non-pollutant aspect of solar energy. Burning fossil fuels is known to produce deadly pollution, while solar energy produces zero harmful byproducts. While current energy sources produce disgusting smells, sounds, and visuals, solar energy produces nothing offensive. Therefore, when considering the health of the planet, the lifelong health benefits of solar energy are unparalleled.
Finally, solar energy has low costs. The cost of solar panels is a one-time purchase. Also, after installation, the lifespan of a solar panel is thirty years. After the initial cost, the solar panel will cost almost nothing. This is a benefit to personal finances, but also peace of mind since there is no worry about rising prices or lack of resources.
In conclusion, these benefits provide support for more people to consider switching to solar power. Both the renewable aspect as well as the non-polluting aspect means that there will be added benefits for individuals, cities, and the planet. The low lifelong cost of installation and maintenance provides a lifetime of benefits. Thus, solar energy looks to be one of the world’s great ideas.