Shark evolution Essay Example for Free

Shark evolution Essay Sharks, commonly referred to as fish are in fact quite different from the regular bony fish. Sharks have a cartilaginous skeleton, which is does not fossilize well, but despite this sharks have left a considerable fossil record. Shark evolution is in fact one of the most successful cases of phylogenic development. The evidence of sharks dates back to over 400 million years ago, almost 200 million years before the first dinosaurs, and before the evolution of any land vertebrates, in the Ordovician period, at the start of the Palezoic era. The only fossils of the oldest sharks are the scales and teeth, the teeth being quite durable and easily mineralized. The teeth in particular reveal that the oldest sharks were quite different from their modern descendants. And even through vertebrates like dinosaurs were eliminated centuries ago, sharks continue to exist today, with almost 1100 species. Among the most primitive sharks was the Cretaceous, discovered in Texas. The Cretaceous is believed to be about 65 million years old. The earliest life on earth dates back to almost 4 billion years ago, to a group called the prokaryotes, which includes the first bacteria. The prokaryotes did not even have a defined nucleus. The oldest eukaryotes, which were more advanced, and had specialized organelles evolved about 2 billion years ago. These included the famous amoeba. But the first multicelluar life form dates back to about 600 million years ago, to the â€Å"Edicarian assemblage† in Australia. Jawless fishes are believed to be the first vertebrates to have evolved, and date back to about 500 million years ago. Sharks then appeared about 450 million years ago. But even though paleontologists have considerable evidence, shark evolution posed many problems because of the fossils. With time, most of the evidence was eliminated. The scales are mostly very small in size, and have many impressions of soft tissues. But despite these drawbacks, studies reveal a rich history. The oldest shark scales go back to about 455 million years ago. But since they are quite different from those in modern sharks, most paleontologists agree that they are not from sharks. The first acknowledged fossil dates back to 420 million years ago in Siberia. These have been classified under the genus of Elegestolepis. Others, discovered from Mongolia have been classified in the genera Mongolepis and Polymerolepis. But apart for these almost classifications, little is actually known about these primitive sharks. But with the beginning of the Devonian period, shark record becomes quite varied. The first teeth of about 400 million years ago were discovered from Europe. These teeth belong to the ancient Leonodus. Leonodus had characteristic double cusped teeth. The oldest shark cranium was discovered in Australia, and dates back to about 380 million years ago, and is believed to be from a shark specie xenacanth. Earlier in fact the Leonodus and xenacanth were thought to be related because of their similar crown shaped teeth. The first partially fossilized shark shark was discovered by a geologist Gavin Young in Antarctica. But this fossil displayed an odd mix of features. Possibility exists that this too may be a xenacanth, but Young named it Antarctilamna. The Antarctilamna was 16-inches long, and was a diplodont, resembling the xenacanth. Antarctilamna’s fin though was directed dorsally. The xenacanth in contrast was exclusively a freshwater shark, and had a long fin directed rearward, just behind the cranium. But with the passage of time, sharks have endured tremendous changes of environment, and yet, have managed to survive. But like all other creatures, the species had to either adapt to the change, or end. Each time a large scale shift occurred; a number of species found the new environment incompatible and became extinct. Sharks though displayed immense diversity, and helping then expand into new habitats. â€Å"Such explosive increases in variety are termed ‘adaptive radiations[1]. ’† Over such a huge span of geologic time, sharks have has two adaptive radiations, and have survived up to five mass extinctions. Many also agree that since most shark fossils have been found either from Australia, or Antarctica, sharks may have originated in the southern hemisphere. The first radiation was in the Carboniferous period, roughly 30 million years ago. This was characterized by the flourishing of the stethacanthids. The second major radiation occurred in the Jurassic Period, about 170 million years ago. During this time both land and air was dominated by reptiles. This was the time when the hybodonts developed. Many believe that the hybodonts were the ancestors of all modern sharks, but evidence is scanty. While the hybodonts shows many obvious similarities to the modern shark, it has characteristic features not found in sharks today. One of these includes the horns behind the eyes. But now, the earliest known modern shark is believed to be the Mcmurdodus from the mid-Devonian time. The basis for this is the Mcmurdodus tooth. The tooth shows is of the same type found in modern sharks, but not in the ancient ones. But â€Å"there is a 190-million-year gap in the fossil record between the last Mcmurdodus and the first unquestionable cowshark [1]. † Even though research continues to unveil the evolution of this epic animal, a complete evolutionary record is difficult to draw. The earliest known sharks in fact were quite different from the modern counterparts. But in some respects they were very close to the modern sharks of today, having the same cartilaginous skeletons, replaceable teeth and multiple gill slits. And with time sharks have endured great geologic change, adapting to different environments, evolving to change, and have thus survived as one the most durable animals on the planet. References 1. Martin, R. Aidan. ReefQuest Centre for Shark Research. Biology of Sharks and Rays. Retrieved from (http://www. elasmo-research. org/education/evolution/evol_s_predator. htm)

Certain responsibilities Essay Example for Free

Certain responsibilities Essay In school, as in life, everyone has certain responsibilities. The Principal is responsible for overseeing the efficient running of the school. The teachers are responsible for seeing that school rules are obeyed, that their lesson plans are well written and lessons prepared. Teachers are also responsible for seeing that each of their students learn the material that is presented. Students are responsible for many things as well. All students are responsible for making sure they are ready to learn. This includes having the necessary equipment to do the job of learning. Each student is responsible for having a all their school materials with them at all times. When a student shows up to class unprepared it makes learning very difficult. Unprepared students also make learning hard for people around them as they disturb others trying to find a pen or borrow a book. Students who come to class unprepared miss important information. While they are looking for a book, or a pen or their homework; knowledge is passing them by. Being unprepared is a sign of immaturity. Students who come to class without a pen are demonstrating that they are not ready and they are irresponsible. They rely on others to take care of their needs. This is unfair to others who have their own lives to take care of. If you don’t want to be treated like a child, you must begin taking responsibility for yourself. This starts with being a responsible student. It’s time for you to step up and take care of your own responsibilities.

The Application Of Computer Graphics Education Essay

The Application Of Computer Graphics Education Essay People that have learning difficulties show deficits in attention, language, and have a lack of interest in teaching and learning environment and also in educational contents. In class they find that it difficult to cope with the subject that has abstract concepts. For example, student that has down syndrome and autism. Therefore, the solution to this is using one of the Computer Graphics applications, the Virtual Reality where in this application they use visual graphic in educational process. The Virtual Reality application gives advantages to some areas such as environment understanding, from literality to symbolism, and social abilities. Based on the Bogdashina O. book, Sensory perceptual issues in autism and asperger syndrome, the sensory profile of people or student with learning difficulties may be different from those who normal. The Virtual Reality application is being used in the case of Virtual School and Virtual Supermarket. The Virtual Supermarket is one of the successfu l examples of Computer Graphics application in commercial. Then Virtual School has made and still under process and development. Both these case is familiar to everyone in this world. Thatà ¢Ã¢â€š ¬Ã¢â€ž ¢s why the application of these two environments has been studied by applying the techniques and application of Computer Graphics. Another application of Computer Graphics in education is as the motivation for Mathematics subject that need students to use a lot of thinking process. Computer Graphics can be a tools for increasing the awareness in the sciences subjects such as Mathematics among students. Because of the application of the real time, interactive, and visual feedback, students can easily observe the effects of the use of Mathematics in produce a good designs. Nowadays, the use of computers in some school has increase due to the increases in the use of technologies. This is due to the decreases in the percentage of the sciences subject such as Mathematics and Science. After introduce the computers to all school this problem has been solving through time. Through this solution, it shows that the use of computers affects the students in their learning process. In this case, Computer Graphics has been used to illustrate how problem solving give advantages from applications of Mathematics thinking to grap hics problems. Graphics tools as the representative has been used as the teaching aids for the teachers to teach their students in class. The area of Computer Graphics is widely used in many of applications for specific purpose. There are many examples of the successful of the Computer Graphics technology in commercial application. Some of the examples are the virtual stimulators for training in driving vehicles, entertainments, visualisations, 3D representations of future buildings or houses, computer and console games, film scenes and the characters that produced using Computer Graphics. One successful example of Computer Graphics technology in commercial application is Virtual Supermarket. Technique that use in this application is three dimensional (3D) graphic. This application consists of 3D supermarket where it has a variety of products and goods, different visual employees and different functionalities available. The basic task in this case is only to do the shopping. Tools that need in this application are only a computer with the screen, keyboard, mouse, and joystick. Firstly, the user has to move inside the supermarket and then searching for the things that list in the spread out shopping list. Use r need to pick a something or product and put into the virtual trolley. There are four modes that being use in this case that related to the application in the Virtual School which is will be use for learning difficulties in school. First is functional of use and play. This mode can be used to teach the important concepts of our daily life environment and it is shown using pre-recorded videos integrated in the virtual world. Second is imagery play, where this functionality mode is possible to teach the student that has special needs about imagery play of the objects. Through this mode the teacher can try to teach the same imagery play to their students without using the computer but between the teachers and the students itself. The third technique is imagery transformations of objects. There are two types of transformations that commonly used which is 2D and 3D transformations. As the technology has improved, the 3D transformation graphics have become more common rather than 2D transformation, but 2D transformation graphics are still widely used. This te chnique is more to abstract concept to show information that difficult to explain and see in the real world. Therefore, using this transformations technique the teachers are able and more easily to explain to their students about what he or she teaching about in class. In this case the transformation is using the 3D graphic animation transformations into the virtual scene. The last mode is imagery use which is the three dimensional viewing. This Virtual Supermarket can be viewed through 3D viewing where the objects seen seem to be real. The user also can listen to what the avatar in the videos saying or talking and can see their expressions. The idea behind and relationship this application to the education are it is not only an educational game but also a tools for teaching. The attraction of people with learning difficulties towards computers shows the increases in the possibilities that these tools have in their educational and learning process. They find that it is easy to use t he graphical interface in their learning process. This help increasing their interest in educational contents. The techniques that have been used in this example are modelling shapes, layout and animation, and rendering. The modelling process can be through polygonal modelling in which dots are connected and the faces of the polygons that result create the image of the objects. A layout and animation technique involves placing the object within the scene. Commonly, some of methods that used in this technique are motion capture of movements, determining the proper angular positions of the elements of the jointed object, and key framing, which is defined the start and end points of a smooth transition through frames. Movement is created by displaying a series of images that are similar to one another on the screen to create the illusion of movement. The frames then can be replaced by a virtual skeleton and the computer automatically calculates the differences in the appearance among succeeding frames. The rendering is the technique where the model is translated into an image by integrating ligh ting effects such as shadows and scatting of light. In this technique it determines how the light is reflected or refracted from a surface at any point in the object and how the properties of the object materials vary on the surface. For the animation graphics educational tools for the science subjects, this application helps in taking attraction from the students to the subject, delivery information that easy for students to understand and many more. In the learning process in the class, teachers could display the information that they want to give to their students via a variety of equipment. This is including the computer monitor, single projector, depending on their teaching and learning needs. In general, the application of graphics animation in the education acknowledged the positive impact on learning in specific situations. This is because of the information that conveyed by graphics animation are more clearly, can be observed, especially when involving the movement and easy to understand. However, if the abstract and the continuous learning, graphics animation may be interfering the student understands about what they learn. Because of the burden of information through graphic presentation animation, the like hood of confusion will occur during the process of selective attention on certain aspects. In this case, graphic animation will ease the cognitive load when the graphic presented in stages. Graphic presentations in stages also have an impact reinforcement to understand and remember the process and facilitate students to encode the information of what they have learned correctly.

The Outsiders :: essays research papers

"The Outsiders" is a story that deals with a conflict between two gangs, the "Greasers" from the East Side of town and the "Socs" from the east-side of town. This is a story that is told in the first person. Ponyboy Curtis is the one telling the story. Here is a summary of the story. Ponyboy has a dispute with his brother Darry and ends up running away to the park with Johnnycake. There, Ponyboy and Johnnycake get into a fight with Randy, Bob, and three other members of the Socs. The Socs try to down Ponyboy, so Johnnycake stabs Bob with a knife and ends up killing him. Ponyboy and Johnnycake run to a party where they meet up with Dallas, one of their close friends. He gives them a gun, money, and tells them to get a train out of town to an abandoned church. They are told to stay there until Dallas comes to get them. When Johnnycake and Ponyboy get the church they go right to sleep. When Ponyboy wakes up, he finds that Johnny has gone to the store to get them food. While there, they both decide to disguise themselves by cutting their hair. Ponyboy decides to bleach his hair with peroxide. Dallas finally shows up to get them. They all go to town to get something to eat. When they return to the church, it was on fire. Ponyboy and Johnnycake went in to save the children from the burning church. Johnnycake is trapped inside. Dallas goes into save him. Then, the church collapses. They are rushed to the hospital. Ponyboy and Dallas are okay, but Johnny is severely injured. Ponyboy talks with one of the Socs and they both discuss about how they are tired of fighting. Everyone should be equal. Later, the Greasers and Socs get into an enormous brawl , but in the end the Greasers win. Ponyboy and Dallas rush to the hospital to tell Johnnycake they won the brawl. Johnnycake tells Ponyboy to stay gold. Those are the last words Johnny spoke before he died. Darry goes crazy over Johnny's death and decides to rob a convenience store. The cops chase him, Dallas fires a few shots at them with his gun.

The Army and Environmental Compliance Essay example -- Environmental I

The Army and Environmental Compliance Since the inception of National environmental awareness and protection policies in the 1970’s, the Army has had to adjust how it conducts training. The development of Army environmental compliance programs, policies and strategies enable the Army to fulfill federal and state requirements governing the use of natural resources, while balancing the need for essential training to maintain combat readiness and relevance. As a direct result of positive environmental stewardship, inclusion of environmental compliance enables the Army to provide continuity of operations while protecting the environment. United States Environmental Policy The modern day involvement of the United States Army’s responsible environmental stewardship began over 40 years ago and continues unabated today. The catalyst was the National Environmental Protection Act (NEPA), signed into law in 1970, which established national policy for the protection of the environment. According to the U.S. Environmental Protection Agency (2011), the Council of Environmental Quality was created to ensure federal and state agencies assess the environmental effects of their proposed actions through scientific analysis and that decisions made include public involvement. Thus, the NEPA process provides the public with information about the Army’s decisions and a mechanism to become informed and involved in actions that impact their environment, health and quality of life. Department of the Army regulation 200-1, Environmental Protection and Enhancement (2007), requires â€Å"the Secretary of the Army to serve as trustee for the natural and cultural resources managed by the Army†. This designation also includes responsibility... ..., Vol. 65, No. 81, April 26, 2000 (p. 24595). Retrieved from http://www. archives.gov/ federal-register/executive-orders/2000.html Office of the Assistance Secretary of the Army for Installations and Environment. (2004). The Army Strategy for the Environment. Washington, D.C. Retrieved May 12, 2012, from http://www.asaie.army.mil/Public/ESOH/doc/ArmyEnvStrategy.pdf U.S. Army Environmental Command. (2011). About us. Retrieved May 12, 2012, from http://aec.army.mil/usaec/aboutus.html U.S. Environmental Protection Agency. (2012). National Environmental Policy Act. Retrieved May 12, 2012, from http://www.epa.gov/compliance/basics/nepa.html#federalrole U.S. Government Accountability Office Report to Congressional Committees (2008). Military Training Compliance with Environmental Laws. Retrieved May 19, 2012, from http://www.gao.gov/new.items/d08407.pdf

The Industrial Revolution for the Disabled :: Essays Papers

The Industrial Revolution for the Disabled In this new age of Internet and the World Wide Web, everything is accessible. If you needed up to date news, research, or entertainment; just go online. Everyday people take this choice for granted, maybe by ignorance or by stupidity, but a small, ever-growing population don't have these choices. The disabled have overcome many pregitouses and were once regarded as mentally and physically retarded. But recently, a number of organizations have recognized the need for the disabled to achieve ultimate web accessibility. Of course, ultimate won't be achieved for a long time, but some accessiblility is better than none. The Americans with Disabilities Act has already come up with accessibility requirements that the Federal Government has adopted. (Applicability of... 2000) Aol has changed it's format due to a law suit by the National Federation for the blind. (Applicability of... 2000) Not only are public sectors changing their websites, but many private sectors are as well (Applicability of... 2000) "To ensure individuals with disabilities have full and equal enjoyment of the facilities they provide when the provision of such access is measureable. (Applicability of... 2000) Assistive Technology "Assistive Technology is any device, piece of equipment, of software that is used to help a person with a disability or impairment, reach full functional capacity. Some examples of high-tech assistive technology include voice recognition systems, voice synthesis, large print display, braille embossing, and alternative computer input devices." (University of Iowa) Some statistics on the widespread concern of developers for accessible websites include:"50 million people in the U.S. have some kind of functional limitation. 15% of those cannot use a computer without some form of assistive technology and about 8% of those who use the Web have disabilities." (McKeefy 1998) As research shows the internet is bringing a world of information to users with disabilities, but adversely, it is difficult for vision impaired people to access a multimedia-rich site. (McKeefy 1998) New equipment for the sight-impaired are now available, but one might think it is only available to people with money. According to Greg Meise, President of Lenexa (a Kansas based reseller), "'Declining technology prices now have made these products available to a wider audience. Affordability has changed the market.'" (McKeefy 1998) The prices of these special technologies have dropped and impaired users have an option of mixed technologies. (McKeefy 1998) Awareness The ADA (Americans with Disabilities Act) has set up requirements for the internet to make web sites accessible for people with disabilities.

English Essay

What does Emerson think of people who call for consistency in thought and action and who fear being misunderstood? ? He believes being foolish is ridiculous and for little minds, and that you should speak your mind uninhibited, and that being misunderstood is not necessarily a bad thing. Many of history’s great minds were misunderstood. 5. Emerson makes many of his points through a series of figures of speech – comparisons between two things that are basically unlike. In â€Å"Self-Reliance† what does he compare with the ordinary things and events listed below. Be sure to respond in complete sentence format. Example: He compares cannon balls to words: â€Å"Else if you would be a man, speak what you think today in words as hard as cannon balls, and tomorrow speak what tomorrow thinks in hard words again, though it contradict every thing you said today. † A. planting corn- Planting corn is compared to basically reaping what you sow. No reward can come unless one puts in hard work, pain, and suffering in life, just like the work that goes into planting and harvesting corn. B. an iron string- An iron string is compared to trust in oneself. ? C. lay- Clay is compared to aspiring men who must let themselves be molded by the â€Å"Almighty effort†. * * â€Å"That government is best which governs not at all;†. Thoreau’s essay, inspired by a night in jail, was a bit biased against the government. Thoreau’s theory of how he believes a government should operate is simply not feasible- it is not reasonable to protest the operation of government policies by breaking the law, and then criticizing the government after spending a night in jail; the government is needed to stabilize a country, to provide order amidst chaos, and to ensure common welfare and health. The government has many functions in a country, and nothing could be accomplished without it- for example, a stabilized economy. Now, some people would argue that the government causes inflation and economic depression, but it is also the only thing that can stabilize it and bring it back into an upswing. By evidence of the Confederate states, before they became the United States, trying to be a united group but having separate small governments does not work. A government with even minimal power cannot collect taxes, enforce its laws, or protect its citizens. Chaos would then ensue. Chaos is also caused by lawlessness, which is in turned caused by a weak government. A wonderful example is the early United States. They attempted a Confederacy, a band of loosely tied states whose government had no real power. They states fought, the people fought against the states, it was mayhem – every man for himself. Laws were broken and justice was exacted in the form of revenge. There was no safety, no guarantees, no order. But with a strong government in place, society can function normally and live in relative peace. There is a system in place to protect, to lead, to help. Without it, all hell breaks loose. And hell is a place of misery and sickness, which is another thing that the government typically seeks to remedy. They may tax their people, but that money Thoreau refused to give up would be redistributed out to people in need. It goes to homeless shelters, veterans, old retired folks, a sick single mother, a young adult struggling to make it out of the ghetto. The government is there for the common good. It helps out the people, because the people elect its officials. There may be a handful who disagree, but the government is typically run by the majorities wishes, so that the majority of its people are at least satisfied, if not happy. A single person can be smart, but people as a collective group are stupid. They are like sheep- they require guidance and leadership in order to run like a well-oiled machine. Therefore the government must have power, and use it to govern. There will always be a andful of people like Thoreau who oppose the government, and argue for the underdog because they feel that the system has not worked in their favor, or even hindered them. But overall, a government is designed for the common good, and governments like the USA and many European countries are doing just that. But there is no point to a government that does not govern, for then it is worse than having none at all. The government is required to ensure the common good, health, and order is enforced and the majority of its people are safe and happy.