Thursday, August 27, 2020

Interesting Facts :: essays research papers

Fascinating Facts Got this from one of my day by day joke messages. Thought it was fascinating enough to share : 111,111,111 x 111,111,111 = 12,345,678,987,654,321 In the event that a sculpture in the recreation center of an individual on a pony has both front legs noticeable all around, the individual passed on because of wounds got in fight; if the pony has each of the four legs on the ground, the individual kicked the bucket of common causes. No word in the English language rhymes with month, orange, silver, and purple. Factions of quite a while in the past that needed to dispose of their undesirable individuals without executing them use to torch their homes - subsequently the articulation "to get fired." Canada is an Indian word meaning "Big Village". There are two Visas for each individual in the United States. Just two individuals marked the Declaration of Independence on July fourth, John Hancock and Charles Thomson. The vast majority of the lay marked on August 2, yet the last signature wasn't included until 5 years after the fact. "I am." is the most brief total sentence in the English language. The term "the entire 9 yards" originated from WWII military pilots in the South Pacific. When equipping their planes on the ground, the .50 bore assault rifle ammunition belts estimated precisely 27 feet, before being stacked into the fuselage. In the event that the pilots terminated all their ammunition at an objective, it got "the entire 9 yards." The most well-known name on the planet is Mohammed. The word "samba" implies "to rub navels together." The universal phone dialing code for Antarctica is 672. The paste on Israeli postage stamps is affirmed legitimate. Mel Blanc (the voice of Bugs Bunny) was adversely affected by carrots. Until 1965, driving was done on the left-hand side on streets in Sweden. The transformation to right-hand was done on a weekday at 5pm. All traffic halted as individuals exchanged sides. This time and day were picked to forestall mishaps where drivers would have gotten up in the first part of the day and been too drowsy to even think about realizing that *this* was the day of the changeover. The absolute first bomb dropped by the Allies on Berlin during World War II slaughtered the main elephant in the Berlin Zoo. Dr. Seuss articulated "Seuss" to such an extent that it rhymed with "rejoice." In Casablanca, Humphrey Bogart never said "Play it again, Sam." Sherlock Holmes never said "Elementary, my dear Watson." A greater number of individuals are slaughtered every year by jackasses than kick the bucket in air crashes. The term, "It's all pointless fooling around until somebody loses an eye" is from Ancient Rome.

Saturday, August 22, 2020

Hospitality and Tourism Essay Example | Topics and Well Written Essays - 2000 words

Friendliness and Tourism - Essay Example is obvious that the business world accompanies numerous vulnerabilities and along these lines, picking up information and data is a method of making an upper hand. Along these lines, a significant element in the cutting edge friendliness and the travel industry is the comprehension of new strategies and methodology through staff preparing. Preparing and direction is crafted by the Human Resource Management (HRM) as a method of upgrading worker execution, while effectively utilizing their ability just as specialization in their activity. It is in this way, critical to comprehend the huge of work force preparing just as direction in accommodation and the travel industry in an offer to improve execution (Barrows and Powers, 2008). The extraordinary changing universe of business requires utilizing human money to improve execution so as to accomplish the authoritative objectives. The human asset chief in the friendliness business ought to comprehend the different changes in globalization, innovative advances, staff decent variety, deficiency of work, and worker association among others (Gonzã ¡lez and Tacorante, 2004). Preparing and supporting representatives is an idea that can't be sabotaged by the human asset since it adds information and capacity to get effective. New workers in accommodation and the travel industry segment need preparing to comprehend their obligations and the current representatives need more information to appreciate the adjustments in this segment. It is clear that careful preparing uncovered an employee’s skills and practices to perform better (Ahammad, 2013). The numerous adjustments in innovation, complex business frameworks, and vulnerability in the business world, call for more information and new aptitudes. Fundamentally, (Gazija, 2011) contends that the neighborliness and the travel industry witness large scale manufacturing and age of various items or administrations and clients are particularly specific when buying them. Thusly, this new requests in the accommodation business need new arrangements and wide

Friday, August 21, 2020

Online Support For Your Dissertation Paper

Online Support For Your Dissertation PaperWhen it comes to the type of information required for your thesis, you are best served by using some of the online resources that are available. If you want to save time and have more control over the outcome of your project, you should certainly use these resources. It is no secret that the online world is a great resource for many different areas of expertise and the same holds true for thesis writing.There are two main ways in which thesis papers can be written, either from scratch or with some form of pre-written information. The former is probably the best option as this is exactly what you will be doing when you take up the subject matter. If you do not feel confident enough in your writing abilities then you should get online help and simply provide the information that you require.An example of a topic that would benefit from this is a pre-established paper for a high school student. While this sounds like something that has to be wri tten all by yourself, it can be done in a variety of ways. Some of the commonly used techniques include:Report Writing. This is actually the most common way that people go about developing their own documents. You can create the outline and move forward from there, but it is important to have an idea of the purpose of the project before you start. This is an excellent way to get the information you need, as it allows you to work on some of the finer details before you even get to the dissertation.Source Material. Students often have to do a lot of the work of sourcing information for their thesis papers as they often find themselves in difficult situations due to the fact that they do not have the necessary skills. Many of the online sources that are available will allow you to find information such as newspapers, magazines and journals.Analysis. Sometimes it is also necessary to do extensive research on the topic at hand before you are able to come up with the final draft. This is one of the most common methods of using online help in this case, and while it will probably take some time to get everything sorted out, it is an excellent way to save time.Good research tools. Some of the online resources that are available will have the option of using the internet to help with this. However, it is still best to take the time to search around the internet and check out a variety of different resources before you begin.Some of the support tools that are available can provide you with an easier option, especially if you have never worked on a thesis before. Theses are not just academic projects, but they are also personal, and this means that your own opinions on the topic matter. Therefore, it is crucial that you write your own opinion on the topic, as this is the best way to ensure that you are getting your point across clearly.

Monday, May 25, 2020

Solubility Product From Solubility Example Problem

This example problem demonstrates how to determine the solubility product of an ionic solid in water from a substances solubility. Problem The solubility of silver chloride, AgCl, is 1.26 x 10-5 M at 25 Â °C.The solubility of barium fluoride, BaF2, is 3.15 x 10-3 M at 25 Â °C.Calculate the solubility product, Ksp, of both compounds. Solution The key to solving solubility problems is to properly set up your dissociation reactions and define solubility. AgCl The dissociation reaction of AgCl in water isAgCl (s) ↔ Ag (aq) Cl- (aq)For this reaction, each mole of AgCl that dissolves produces 1 mole of both Ag and Cl-. The solubility would then equal the concentration of either the Ag or Cl ions.solubility [Ag] [Cl-]1.26 x 10-5 M [Ag] [Cl-]Ksp [Ag][Cl-]Ksp (1.26 x 10-5)(1.26 x 10-5)Ksp 1.6 x 10-10 BaF2 The dissociation reaction of BaF2 in water isBaF2 (s) ↔ Ba (aq) 2 F- (aq)This reaction shows that for every mole of BaF2 that dissolves, 1 mole of Ba and 2 moles of F- are formed. The solubility is equal to the concentration of the Ba ions in solution.solubility [Ba] 7.94 x 10-3 M[F-] 2 [Ba]Ksp [Ba][F-]2Ksp ([Ba])(2 [Ba])2Ksp 4[Ba]3Ksp 4(7.94 x 10-3 M)3Ksp 4(5 x 10-7)Ksp 2 x 10-6 Answer The solubility product of AgCl is 1.6 x 10-10.The solubility product of BaF2 is 2 x 10-6.

Thursday, May 14, 2020

The Mythology Of The Iliad - 1277 Words

In The Iliad, the Olympian Gods were depicted as a group of individuals who were still completely vulnerable to mistake and harm despite their great power. Zeus was one, if not the biggest and most powerful God among all other Gods. Known as the King of the Gods, Zeus was a mighty, dominant, and seemingly supreme God, despite his tendency to show surprising silliness and sometimes, the lack of wisdom through his choices, especially when it came to love affairs, which eventually led to many problems that could have been prevented. Zeus, in The Iliad, Zeus is a representation of how ancient Gods were just normal humans equipped with a great degree of power and capabilities, but they have the tendency to show humanly behavior and mistakes. In the Homer’s Iliad, Gods are very susceptible to human desire. At some point, Gods can act more â€Å"human† than actual humans would act. They would think, act, speak, and do other things just like a human being. The only thing that s eems to differ Gods and human is their immortality, power and authority over things. Compared to the gods found in Abrahamic religions, Greek Gods base their decisions and action without principle but feelings and their personal opinion. Greek God are known to be capricious, prone to arguments over insignificant things, showing a very close relationship with human behavior. These characteristics of Greek Gods are probably generated due to the lack of need to thrive and survive since they are immortal andShow MoreRelatedGreek Mythology And Mythology Of The Iliad, Oedipus Rex And Others1294 Words   |  6 Pagesbeen shaped by mythology and religion. The impacts of ancient cultures in particular are felt worldwide through a variety of mediums. Others have referenced ancient cultures for a long time, in hopes of better understanding them. Examples of this have been seen throughout the world, especially in Greek culture. The ancient Greeks had a rich culture, which they used often in t heir works; examples of this are seen in the Iliad, Oedipus Rex and others. The existence of Greek mythology and narrativesRead MoreGreek Mythology : The Epic Tale The Iliad1179 Words   |  5 PagesGreek mythology played a large role in Greek artistic styles and functions. In the case of this study, the mythological god Apollo is the subject of the artistic works of the votive known as the â€Å"Mantiklos Apollo† and the statue of â€Å"Apollo† that was found in Pireaus. These figures show a natural progression in style and technique. They are important because they represent the sacred beliefs and superstitions of their respective cultures and time periods. The two stylistic periods represented inRead MoreConflict Within The Mythology Of The Iliad By Homer946 Words   |  4 Pageswith emotion and struggle between the forces as they try to combat each other through various means. There are many catalysts to these struggles that range from internal conflict to that of external conflicts. One case of this is explored within The Iliad by Homer. Written within the Bronze Age, it depicts the events that took place during the Trojan War between 1194- 1184 BC. This war is initiated by the Judgement of Paris, which was ultimately won by the .within the Rage of Achilles, detailing theRead MoreGreek Mythology By Homer s Odyssey, Iliad And Hesiod s Theogony2522 Words   |  11 PagesGreek mythology as it exists today was a culmination of oral tradition that was part of the early Greek civilization. Different regions of the Greek empire had different heroes with their own traditions, and thus Greek mythology was firmly tied to it geographical loca tion. Geography and physical places helped shape Greek mythology to a large extent. Homer’s Odyssey, Iliad and Hesiod’s Theogony are examples of Greek mythology where the myth is tied with the geographical space. With the mention ofRead MoreHelpless Mothers: Ceres and Andromache981 Words   |  4 Pagesboth the Iliad and in Ceres and Proserpina is the role of women in Greek and Roman mythology. To read the history of Ancient Greece as it has been written for centuries is to enter a thoroughly male world (Blundell, 226). When it comes to a poem like the Iliad, this is even more particularly true as the reader enters a universe of war, where women are very much on the peripheral and the men are the dominant characters directly implied in the bulk of the action (Blundell, 47). The Iliad is a poemRead MoreGreek Mythology And The Mythology850 Words   |  4 Pagesmedicine, and a multitude of others. The mythology of these two cultures is exceedingly similar, although for those looking for a more interesting view on the subject, Greek mythology is far superior to Roman mythology. The time period in which mythological tales were told began over one hundred years ago in 19 BC for the Romans through the epic Aeneid; however, Greek mythology has existed longer. There is no specific evidence proving when Greek mythology actually began; Greek myths are chronicledRead MoreThe Iliad And The Odyssey977 Words   |  4 Pagesthemes in the majority of Ancient Greek mythology is the act of divine intervention. In Greece during ancient times the polytheism of the people played a very large part in each aspect of their daily lives, so it was only natural for them to be included in their mythology. There is not a single Greek myth in history that does not contain some mention of at the very least a single god who played a part in the tale. In one way or another, gods within mythology affect the characters of the myths, theRead MoreMorality In Hesiod And Homers Theogony And The Iliad763 Words   |  4 PagesIn ancient Greece, the two poets Hesiod and Homer wrote dramati c stories outlining the nature of the Greek gods with their main works Theogony and The Iliad. They each offer descriptions of order, morality, and justice in the world, but there is a stark difference between each author’s work; Homer’s mythology features much more authoritative deities than Hesiod’s, ultimately establishing a more political, absolutist social order. The gods’ interactions with each other and with the human world areRead MoreThe Greeks and The Illiad Essay examples1378 Words   |  6 PagesThe Greeks and The Illiad The Iliad was a masterpiece of a work, which entertained and gave a description of how the Greeks lived out their lives in battle and at peace. The Iliad, by Homer, is an epic classic set in Ancient Greece. The story ,in its own, contained the use of epic characteristics, which reveal further characteristics of the Greeks. A large influence on the book, was the Greeks religious and mythological stance along with their strengths and weaknesses that were alsoRead MoreEssay on The Impact of Women in The Iliad579 Words   |  3 Pagesthe decisions that Franklin D. Roosevelt made. Women of Homers epic, The Iliad, were considered primary instigators of the Trojan war. The characteristics attributed to women in ancient Greek mythology may have been key to the outbreak of the war. But many ask why Homer would choose to reflect so deeply on the feminine roles of this war fought by men. Although the beginning of the war was not spoken of in The Iliad, the origin of the war is traced back to jealous goddesses. The gods and goddesses

Wednesday, May 6, 2020

Animal Endangerment And Extinction Of Habitat - 925 Words

I. Animal Endangerment/Extinction II. Abused/Abandoned Animals III. Over Farming/Land Misuse IV. Environmental Pollution V. Deforestation I. Animal Endangerment/Extinction A. Destruction of Habitat B. Pollution C. Hunting and Fishing II. Abused/Abandoned Animals A. Confined, Major Culprit Climate Change B. Huge Amounts of Manure, Pollutes Soil C. Dead Animals, Pollutes the quality of life for individuals who live close. III. Over Farmed/Land Misuse A. Soil Erosion B. Land Degradation C. Genetic Erosion IV. Environmental Pollution A. Grave and Irreparable Damage B. Air Pollution C. Water, Soil, Noise, Light V. Deforestation A. Permanent Destruction of Forest B. Damage to the quality of Land C. Excessive Devastation/Clearing I. Animal Endangerment/Extinction A. Destruction of Habitat/Effects on the environment 1. Animals are endangered and becoming extinct, because humans have no regards for the natural habitat that animals need to survive, less causing animal death which pollutes soil. 2. Animals are used in environmental enrichment strategies, and wildlife research, etc. B. Pollution 1. The presence or introduction into the environment of a substance, or thing that has harmful or poisonous effects. 2. Pollution effects, Environmental pollution has been a fact of life for many years/centuries, but it became a real problem since the state of the industrial revolution. C. Hunting and Fishing/Effects on the Environment 1. Hunting effects many things,Show MoreRelatedWhat Causes Mammals To Be Extinct?1098 Words   |  4 Pagesthe world, there are many factors that cause mammals to become extinct. Climate change is a common factor in what causes mammals to become endangered and later extinct. Climate change mostly caused extinction for two out of every three large mammals in the world. Some mammals that went into extinction because of global warming were: Mammoths, Arabian gazelle, Bulldog rat Central rock rat, Columbian hutia, Corozal rat, Corsican shrew, Cuban spider monkey, Curacao sloth, Dark flying fox, Darling DownsRead MoreThe Extinction, Endangerment, And Captivity Of Endangered Species1540 Words   |  7 Pagesabout the extinction, endangerment, and captivity of endangered species? That is the pressing question that seems to bug all environmentalists and scientists are stressing over, how long will it take for all of your animals to die out? And is it something we can stop or at least contain meanwhile we are trying to find the long-term solution for. Can we prevent this from happening all together? Or is it far too late to save our species that are dying out? We should worry about the extinction, endangermentRead MoreEssay on Wildlife Endangerment Due to Human Intervention in Nature1624 Words   |  7 PagesWildlife Endangerment Due to Human Intervention in Nature The driving force behind today’s alarming decline in species is the destruction, degradation and fragmentation of habitat due to our increasing human population and wasteful consumption of resources.1 Everyday wildlife is forced to seek refuge in very remote, small areas. As the human population increases, land that was once inhabited by wildlife is urbanized to suit human needs. In other words, the land available for wildlife to surviveRead MoreThe Factors That Play Into Endangered Species2685 Words   |  11 Pageseven the plants blooming in the spring? Now, more than ever, a lot of species are being exposed to endangerment. Right about now, scientists emphasize â€Å"forty-one thousand, four hundred and fifteen species are on the IUCN Red list (ARkive.org). The Red list is the world’s inventory of the global status of biological species sixteen thousand, three hundred and six of species are threatened with extinction(iucnredlist.org). A species goes extinct if it is not able to adapt to changes in its environmentRead MoreEndangered Animals Are Endangered Species1178 Words   |  5 PagesEvery year Florida’s wildlife animal numbers decrease at an alarming rate. Endangered animals exist all over the world, but Florida’s official state animal is one of the most endangered animals in the entire world. The main reason some animals become declared as endangered is humans. Humans have caused a huge toll on the wildlife’s lifespan and have become a burden in their natural way of living. It is how the human population behaves that decides whether these animals can live a normal life or pushesRead MoreEndangered Tigers : The Threats Of Endangered Tigers824 Words   |  4 Pagesthen the next day theyre gone. If tigers endangerment stays the same, with nobody willing to help out, this could be very plausible Tigers are facing endangerment at an extreme level. This endangerment is caused by poaching, humans killing tigers for tradi ng and using their body parts, habitat loss and captivity. If something didn’t happen to save tigers, not too long in the future kids growing up wouldn’t know what a tiger is because of its extinction. There are multiple different types ofRead MoreAnimal Testing and Hunting: Stopping the Slaughter Essay766 Words   |  4 Pages We, as humans, mistreat the animal population. On a smaller scale, the human population wastes domestic and wild, animals for medical testing, for their fur, and for entertainment such as dog fighting. These things may not seem to be globally threatening, yet the constant waste of certain species of animals and the destruction of an animals natural habitat will lead to the endangerment and eventually the extinction of the species. Furthermore, many people are unaware that the world is currentlyRead MoreThe Conservation, Rehabilitation, And Release1358 Words   |  6 Pagesthey sexually mature? Everyday, non-human primates are being taken out of their wild habitat, illegally exported in horrible conditions, and breed in captivity; these are wild animals and cannot be domesticated. Conservation, rehabilitation, and release are key to the reconstruction of these endangered non-human primates and everything they know. The main cause for most primate problems is that their habitats are rapidly declining and eliminated entirely. All non-human primates are categorizedRead MoreThe Species Of Endangered Species1474 Words   |  6 PagesDid you know that the endangerment or eventual extinction of a species causes the endangerment and extinction of other life forms, eventually leading to a negative impact on human well-being? Currently, the endangered species list includes 16,306 species that are endangered and at risk of extinction, and 785 species have already gone extinct (Kasnoff). On the list of endangered species is the adorable sea otter. Sea otters are not only cute, but they play an extremely important role in the ecologicalRead MoreWhat Is An Endangered Species?1967 Words   |  8 Pages An Endangered Species is defined as â€Å"a species at risk of extinction because of human activity, changes in climate, and/or changes in predator-prey ratios† (Dictionary.com). The U.S. Fish and Wildlife Services (USFWS) has the responsibility of keeping the records of all endangered species. In order to be recognized as an endangered species, the following questions must be answered: â€Å"Has a large percentage of the species vital habitat been degraded or destroyed? Has the species been over-consumed

Tuesday, May 5, 2020

Phylogenetic Classification Systems †Free Samples for Students

Question: Discuss About the Phylogenetic Classification Systems? Answer: Introducation The earlier taxonomic and phylogenetic classification systems were based on morphology. As the science of microscopy developed and it became possible to study the cellular structure, classification of organisms was based on the differences in cell structure. With the advent of ability to sequence DNA and RNA, it became possible to compare the sequences. This led to the ability to distinguish between organisms on the basis of dissimilarities between the sequences. The three tax domains as per the current system of classification are eubacteria and archaeabacteria, both prokaryotic and the eukaryotes. Prokaryotes and eukaryotes were earlier differentiated on the basis of cellular morphology. The absence or presence of nucleus was the main structure that differentiated them. Carl Woese suggested that the classification should be based on the 16S rRNA or 18S rRNA sequences rather than on morphological differences (Woese, Kandler, Wheelis, 1990). The basis for earlier methods for classification was organism based, it was later based on cellular Management and is now based on differences at the molecular level. As a result phylogeny is now understood on a molecular basis rather than a phenotypic basis. The basis for description of eukaryotes appeared to be based on the shared complexity of cellular organisation. But the same was not true for prokaryotes, the differences amongst the organisms could not be phylogenetically described just because these cells did not contain a nucleus. This was revealed when it was discovered that the archaeabacteria are as different from bacteria as the y are different from the eukaryotes and thus three domains were proposed, namely, eubacteria, archaeabacteria and the eukaryotes. The archaeabacteria that were studied later are methanogenic, thermophilic and tolerant to high salt concentrations, conditions that were prevalent on earth in ancient times. All organisms have DNA and the genes are expressed through protein synthesis. Ribosomes are the sites for protein synthesis and rRNA molecules are components of ribosomes. The rRNA molecules are also encoded by DNA. Mutations have occurred in the rRNA genes during evolution. The reason why rRNA was suited to be the molecule of choice for molecular phylogeny was because it was present in all organisms and the mutations that occurred in the molecule were such that they allowed the formation of ribosomes. Any mutation that could have disrupted the formation of ribosomes was eliminated through natural selection. rRNA can be easily isolated in the laboratory and comparison of rRNA sequences from two organisms can help determine how closely (or distantly) they are related on an evolutionary time scale. The rRNA molecules fold into secondary and tertiary structures due to complementary base sequences. The tertiary structure of rRNA exhibits differences between eubacteria, archaebacteria and eukaryotes. The small subunit rRNA in the eubacteria is different from the archaebacteria and eukaryotes between bases 500 to 545 that form the bulge that protrudes from the stalk in the tertiary structure. It is 6 nucleotides long in the former while the bulge is made up of seven nucleotides in the latter, the compositions of the nucleotide stretches are also different in eubacteria. The region of small subunit rRNA in eukaryotes has a sequence between nucleotides 585 and 655 which is peculiar to the domain (Gutell, Weiser, Woese, Noller, 1985). The prokaryotes have a different but common structure in the corresponding region. The archaebacteria have a unique domain in their 16S rRNA between 180-197 positions and between 405 and 498 positions (Woese, Gutell, Gupta, Noller, 1983). A comparison of the three domains yields similarities between the eubacteria and the archaeabacteria but more similarities occur between the archaeans and the eukaryotes. The nuclear membrane and unit-membrane enclosed organelles are present in the eukaryotes but re absent among the two prokaryotic domains. The eubacteria have a peptidoglycan cell wall that is absent in the other two domains. Eubacteria have only one kind of RNA polymerase while archaebacteria and eukaryotes have several kinds of RNA polymerases that share structural homology (Huet, Schnabel, Sentenac, Zillig, 1983). During protein synthesis the initiator amino acid among the eubacteria is formyl-methionine, but methionine is the initiator amino acid in the other two domains. Both archaebacteria and eukaryotes have genes with introns but eubacteria have genes without introns. Antibiotics like streptomycin and chloramphenicol can only inhibit the eubacteria. DNA is packaged with the help of histone proteins in the eu karyotes, some archaeabacterial species but none of the eubacteria. The prokaryotes have circular chromosomes. Some species of archaeabacteria are thermophilic and can grow beyond the temperature of 100oC. Thus there are several similarities between the archaebacteria and eukaryotes (Reece, et al., 2014). In conclusion, the new system of taxonomic classification is based the differences between the rRNA and some gene sequences. The position of the archaeabacteria as a separate domain has been established based on their similarities with eukaryotes and the eubacteria. The similarities and mutations in the small subunit of rRNA have been extensively studied to establish the domains and form the basis for molecular phylog References Gutell, R. R., Weiser, B., Woese, C. R., Noller, H. F. (1985). Comparative anatomy of 16-S-like ribosomal RNA. Progress in Nucleic Acid Research and Molecular Biology, 32, 155-216. Huet, J., Schnabel, R., Sentenac, A., Zillig, W. (1983). Archaebacteria Accounting eukaryotes possess DNA-dependent RNA polymerases of a common type. EMBO, 2(8): 12911294. Reece, J., Urry, L., Cain, M., Wasserman, S., Minorsky, P., Jackson, R. (2014). Campbell Biology. Pearson. Woese, C., Gutell, R., Gupta, R., Noller, H. (1983). Detailed analysis of the higher-order structure of 16S-like ribosomal ribonucleic acids. Microbiological Reviews, 47(4): 621669. Woese, C., Kandler, O., Wheelis, M. (1990). Towards a natural system of organisms: Proposal for the domains. PNAS, USA, 87: 4576-4579, .