Aristarchus of Samos Biography

Much of what we know about the science of astronomy and celestial observations is based on observations and theories first proposed by ancient observers in Greece and what is now the Middle East. These astronomers were also accomplished mathematicians and observers. One of them was a deep thinker named Aristarchus of Samos.  He lived from about 310 B.C.E. through approximately 250 B.C.E. and his work is still honored today. Although Aristarchus was occasionally written about by early scientists and philosophers, especially Archimedes (who was a mathematician, engineer, and astronomer), very little is known about his life. He was a student of Strato of Lampsacus, head of Aristotles Lyceum. The Lyceum was a place of learning built before Aristotles time but is most often connected to his teachings. It existed in both Athens and Alexandria. Aristotles studies apparently did not take place in Athens, but rather during the time when Strato was head of the Lyceum at Alexandria. This was probably shortly after he took over in 287 B.C.E. Aristarchus came along as a young man to study under the best minds of his time. What Aristarchus Achieved Aristarchus is best known for two things: his belief that Earth orbits (revolves) around the Sun and his work attempting to determine the sizes and distances of the Sun and Moon relative to each other.  He was one of the first to consider the Sun as a central fire just as the other stars were, and was an early proponent of the idea that stars were other suns.   Although Aristarchus wrote many volumes of commentary and analyses, his only surviving work, On the Dimensions and Distances of the Sun and Moon, does not provide any further insight into his heliocentric view of the universe. While the method he describes in it for obtaining the sizes and distances of the Sun and Moon is basically correct, his final estimates were wrong. This was more due to a lack of accurate instruments and an inadequate knowledge of mathematics than to the method he used to come up with his numbers. Aristarchuss interest wasnt limited to our own planet. He suspected that, beyond the solar system, the stars were similar to the Sun. This idea, along with his work on the heliocentric model putting the Earth in rotation around the Sun, held for many centuries. Eventually, the ideas of later astronomer Claudius Ptolemy — that the cosmos essentially orbits Earth (also known as geocentrism) — came into vogue, and held sway until Nicolaus Copernicus brought back the heliocentric theory in his writings centuries later.   It is said that Nicolaus Copernicus  credited Aristarchus in his treatise, De revolutionibus caelestibus.  In it, he wrote, Philolaus believed in the mobility of the earth, and some even say that Aristarchus of Samos was of that opinion. This line was crossed out prior to its publication, for reasons that are unknown. But clearly, Copernicus recognized that someone else had correctly deduced the correct position of the Sun and Earth in the cosmos. He felt it was important enough to put into his work. Whether he crossed it out or someone else did is open to debate. Aristarchus vs. Aristotle and Ptolemy There is some evidence that Aristarchuss ideas were not respected by other philosophers of his time. Some advocated that he be tried before a set of judges for putting forth ideas against the natural order of things as they were understood at the time. Many of his ideas were directly in contradiction with the accepted wisdom of the philosopher  Aristotle and the Greek-Egyptian nobleman and astronomer Claudius Ptolemy. Those two philosophers held that Earth was the center of the universe, an idea we now know is wrong.   Nothing in the surviving records of his life suggest that Aristarchus was censured for his contrary visions of how the cosmos worked. However, so very little of his work exists today that historians are left with fragments of knowledge about him. Still, he was one of the first to try and mathematically determine distances in space.   As with his birth and life, little is known of Aristarchuss death. A crater on the moon is named for him, in its center is a peak which is the brightest formation on the Moon. The crater itself is located on the edge of the Aristarchus Plateau, which is a volcanic region on the lunar surface. The crater was named in Aristarchuss honor by the 17th-century astronomer Giovanni Riccioli.   Edited and expanded by Carolyn Collins Petersen.

The Nature Of Infectious Disease - 2542 Words

The nature of infectious disease remains a far-reaching catalyst of poor public health. The inflation of new diseases, re-emergence of diseases and antimicrobial resistance to drugs is the result of changes in society and the microorganisms themselves (Cohen, 2000). The employment of drugs to prevent and combat disease often leads to drug resistance, as determined in the current antibiotic crisis. New ways of combating disease will and are being set up, such as the new budding theory of cross-reacting immunisation in bacterial infections. The primary weakness with this theory is that as a newfangled concept, its own complications will likely unfold. Pathogens are the causal agents of infectious disease and pathogens include micro†¦show more content†¦Viruses are especially adept at this. Helical viruses look rod shaped under a microscope and can be fixed or flexible (Gillen, 2007). Viruses lack the power to make up proteins and metabolize sugars and need a host to live. Vir uses locally invade membranous tissue, replicates and grows and finally causes infection in the target organ (skin, lungs, or nervous system). The virus then opens to the bloodstream after injecting their DNA into a cell, bursting from the cell, destroying the cell and then continuing to infect other cells (Sompayrac, 2002). A central component of a viruses’ structure which allow it to operate as a pathogen is its antigens [See: Figure 1]. Viruses are refined in their power to adapt and mutate their antigens through antigenic variation which prevents the immune system from seeing the correct antibody, giving the virus time to spread (Craig and Scherf, 2003). HIV is a virus which prevents CD4+ cells (Th cells) from activating the body’s immune response, through cell signalling. Thus, when a virus enters the body, it can dominate the immune system in an HIV+ host; allowing for opportunistic infections, such as pneumonia, which can kill. Thus, the nature of viral infectio ns is etiologic to a virus causing disease in hosts with a deficient immune system. In HIV, the virus remains latent in cells until viral transcription and translation

Whispered Persuasive Essay Samples Staar Secrets

Whispered Persuasive Essay Samples Staar Secrets There are quite a lot of kinds of essays you might be assigned to finish. You could also see expository essay. You could also see descriptive essay. Since you may see, the narrative essay isn't complicated whatsoever. Narrative essay is just one of the most fascinating forms of essays. Books ought never to be banned. You're sharing a typical fear and you aren't alone! Unfortunately, there's still a massive group of individuals who don't know a lot about the many improvements in technology we enjoy today. MP3 music ought to be free. Although online education may not appear to be substantial enough in contrast to the traditional one, it possesses lots of solid advantages you should think about. You can also see persuasive speech. Although it's not recommended, paraphrasing the quote in your essay is an excellent approach to hold up your argument. Education began to be considered a right, and even some type of civic duty. Some feel parents ought to be allowed to provide permission for their minor children to acquire tattoos, because they are making the decision for their own children. Life After Persuasive Essay Samples Staar Just because you've got four body paragraphs or you have eight examples doesn't signify that you're writing an excellent essay. Quite a few alternative logical structures for essays are visualized as diagrams, making them simple to implement or adapt in the building of an argument. The instances that could be cited within this kind of essays don't really must be extremely rare and anything mundane may also be written on it. To do that, it is first of all essential to formulate an issue and attempt to discover effective way of solving it. Since the content of narratives essay can vary when it has to do with unique institutions, we've resolved to supply you with examples in the event you face an issue. Most academic essay topics usually ask you to select a side in an argument or maybe to defend a specific side against criticism. Expository essay employs formal language to talk about someone or something. A narrative essay is permissive in terms of picking the topic. My main fear it is also possible to share your main fear or fears. There's no need to discover extraordinary stories to compose a narrative essay that's interesting to read. It's better to write and share your own personal stories with different folks. If you're fortunate enough to travel from time to time, ensure you write about the situations you've seen and the people that you've met. Persuasive writing can be hard, particularly when you're made to face with a close-minded audience. Body paragraphs reveal the principal events explained in the essay. Through the span of history, writing was used to begin a revolution. As the very best writing experts. Persuasive Essay Samples Staar: the Ultimate Convenience! School should occur in the evenings. Students ought to be permitted to pray in school. Teens ought to be able to select their bedtime. They should be required to take parenting classes. The Persuasive Essay Samples Staar Cover Up The finest persuasive short essays often concentrate on controversial problems. Inside this section you'll find samples of essays belonging to several essay types and manners of formatting. One of the most usual forms of writing is essay writing. If you must compose a narrative essay, this handy guide will explain precisely how you want to do it. Thus, let's take a peek at how to begin a narrative essay. If you are searching for one, below is a list of topic that might help you in your narrative essay. You are able to come across narrative essay examples wherever you locate a superior story. Reviewing some narrative essay examples will be able to help you to organize your information and help you decide how to compose each paragraph to acquire the best outcomes. Year round school isn't a good idea. Life is far better than it was 50 decades ago. If you don't feel as if you have enough time to compose essays by yourself, we will assist you, any instance of the day, seven days per week. Snow days are excellent for family quality time.