A Flea is a common small wingless insect. Fleas, being external parasites, live by hematophagy off the blood of mammals and birds that they live on. There is several different species of fleas, with the most well known being: - Cat Flea - Dog Flea - Northern Rat Flea - Oriental Rat Flea It is rare that flea's become damaging to their host; in most cases they are just nuisances. There can however become a problem when the host suffers an allergic reaction to the flea saliva. Spots where fleas bite are normally visible by a slightly raised and itchy swolled spot, that will have a single puncture at the center. It is important to note that opposite to what I said above, fleas can transmit diseases. This is a rare scenario, but does happen, and an example is the bubonic plague where the disease was transferred between rodents and humans. If that is not bad enough Murine typhus fever and even some cases of tapeworms can be transmitted by fleas. Fleas are busy little insects and will pass through a complete life cycle, egg to adult, in as short as two weeks to as long as eight months, depending on environment conditions. Generally after a blood meal a female flea will lay eggs, about 15 per day, and up to about 600 in its whole lifetime. The eggs are generally layed on the host, and will often times drop off the host. These Flea eggs take between 2 days to 2 weeks to hatch.
It was mentioned on a biology blog that archaeological engravings from the Tiwanaku civilization in Bolivia are unlikely to be depicting an ancient astronaut for the reason that, even with an aquatic tail, the creature still looks too much like a human. The underlying argument was that the evolution of life forms is so diverse that it is highly unlikely an alien would come out looking even remotely like us. In essence, this is the opposite side of the pendulum to Hollywood's consistent imaging of aliens as humanoids. The biologist ignored the decorative and symbolic imagery added by the Tiwanaku artists and did not consider the given premise of an aquatic alien inside helmeted spacesuit. I have to assume, therefore, the biologist noted that the creature had two arms and two eyes, and since humans have two arms and two eyes, the biologist concluded that this cannot be an alien. What should intelligent aliens look like? Or, to phrase it another way, what should we expect interstellar travelers who come here to look like? This is not a complete unknown. If the aliens are capable of interstellar travel, they obviously achieved higher technology. What is necessary to achieve technology? My opinion on this is that to achieve technology, a life form would need a complex brain and the ability to see and manipulate objects. This implies eyes, fingered appendages, and perhaps a head relatively large compared to overall body size. The Tiwanaku alien has all these features. The biologist might counter that the issue is not that aliens have eyes, but the number of eyes. Here on Earth, higher animal forms evolved with two eyes. For example, mammals, birds, fish, reptiles, and insects all have two eyes, but on another planet the number of eyes would be different. There, perhaps, the life forms would randomly have one, three, four, or even ten eyes. Is that true? Is the number of eyes a random event in the evolutionary process? Astronomers searching for extraterrestrial intelligence are looking for planets similar to Earth regarding temperature and chemical composition because they know life evolved here, so it is logical to assume that life might also evolve on other similar planets. Likewise, with similar planetary history, we might expect the evolutionary process on those other planets to progress similarly to how it progressed here. Question: Was the evolution of animal life with two eyes on Earth a random event, so much so that we should expect extraterrestrial life to have a different number of eyes? I think not. Why? It is called natural selection or survival of the fittest. Two eyes are the minimum required to give depth perception and concentrated focus. Perhaps early on Earth there were animals with five or ten eyes, but with a brain too small to orientate five directions, such species quickly became extinct. Only two eyes survived. Should we expect something radically different on another Earth-like planet? No. It is reasonable to expect intelligent aliens to have two eyes, just like humans. It is also reasonable to expect alien life forms to be imaginable from the diversity of life forms we see on Earth, past and present. The Tiwanaku alien has features similar to a fish (fish mouth that seems to be breathing inside a water-filled helmet), features similar to a lobster (sea creature with two forward appendages for manipulating objects), and features similar to humans (large head and fingered upper appendages). Only four fingers are depicted in the Tiwanaku drawings, versus our five, but this easily falls within evolutionary feasibility. The alien's three-pod aquatic tail is also an imaginable evolutionary development. I think the biologist's appreciation for the potentially enormous diversity of life forms in the universe is admirable. For those life forms that develop higher technology, however, it is likely, not unlikely, that they will have something in common with humans. This article referred to Bella Online Biology comments on the Tiwanaku Alien pages of the CrypticThinking.com website.
What are some of the possible complications of Lasik eye surgery? Undercorrection – this occurs when the expected vision correction falls short of the desired outcome. This occurs more commonly with patients who have a high degree of nearsightedness (only objects close up are clear), farsightedness (only objects far away are clear) or astigmatism (images both far and near are distorted). Why? There is more laser corneal sculpting that needs to occur with patients having higher degrees of vision imperfection. When choosing your Lasik eye surgeon, it’s important to ask them what percentage of their patients need retreatment for undercorrection. This should be something that they are willing to freely discuss with you. If not, walk away! This is not to be confused with a planned slight undercorrection for nearsighted patients over forty years old which aids their reading vision. But this is something that you and your Lasik eye surgeon would have discussed before your surgery. Overcorrection – this complication occurs less frequently than undercorrection and results when the amount of correction (corneal laser sculpting) exceeds what is planned. Slight overcorrection can be temporary and may resolve itself in the first month following Lasik eye surgery. Patients can manage slight overcorrections by wearing glasses until their vision resolves. Some patients with overcorrection may need additional Lasik eye surgery 3 to 6 months following their first surgery. Dry Eye – many Lasik eye surgery patients may experience the feeling of ‘grittiness’ in their eyes following surgery. This condition usually resolves itself in 3 to 6 months and may be helped by using lubricating eye drops. Patients using birth control pills and patients going through menopause may experience this condition more often. If ‘dry eye’ continues beyond 6 months, your Lasik eye surgeon may recommend blocking your tear ducts with tiny silicon plugs to prevent tears from draining away too quickly. Corneal abrasion – a small percentage of Lasik eye surgery patients may develop a small corneal abrasion (scrape) caused by the microkeratome (instrument used to create corneal flap) used during surgery. This abrasion is generally not serious and will heal quickly. Your Lasik eye surgeon may temporarily place a thin bandage contact lens on your eye to promote healing. While your abrasion is healing, your vision will be blurry. Night glare – this annoying condition may not affect your vision clarity but patients may see halos or ghosting of images at night during the first month following surgery. Night glare generally improves in 3 months and often disappears within 6 months. Patients with large pupils and more severe vision impairment may be more prone to night glare. Corneal flap complication – this occurs when the corneal flap is too small, too thin or is an irregular shape. In some cases the corneal flap may shift slightly following surgery if a patient rubs their eyes during the first 6 hours after surgery. If the flap does shift, ‘wrinkles’ can form causing distorted vision. A second procedure may be necessary to ‘smooth out’ the wrinkles and improve vision. Infection – although this is the most feared complication of Lasik eye surgery patients, it is extremely rare. If your eye is going to become infected, chances are it will happen in the first 72 hours following surgery and will be treated with antibiotic eye drops. For this reason it is very important to avoid eye makeup, hot tubs and swimming pools for at least the first week following Lasik eye surgery. The risks of Lasik eye surgery are low with an experienced Lasik eye surgeon but you need to be aware of possible complications prior to surgery. Your Lasik eye surgeon should freely discuss all possible complications of Lasik eye surgery prior to surgery. Do everything you can to put your eyes in the best possible hands.
Leonardo da Vinci was a painter, sculptor, architect, cartographer, engineer, scientist and inventor in the 15th century. Yet, despite his genius, he referred to himself as "senza lettere" (the illiterate, the man without letters). For good reason: until late in life, he was unable to read, or write, Latin, the language used by virtually all other Renaissance intellectuals, the lingua franca, akin to English today. Nor was he acquainted with mathematics until he was 30. Leonardo was born out of wedlock but was raised by his real father, a wealthy Florentine notary. He served at least ten years (1466-1476) as Garzone (apprentice) to Andrea del Verrocchio and painted details in Verrocchio's canvasses. Only in 1478, when he was 26, did he become independent. He was not off to an auspicious start. He never executed his first commission (an altarpiece in the chapel of the Palazzo Vecchio della Signoria, Florence's town hall). His first large paintings were left unfinished ("The Adoration of the Magi" and "Saint Jerome", both 1481). Most of the sketches and studies for Leonardo's works of art and engineering are found on his shopping lists, personal notes, and personal expenditure ledgers. No one was allowed to enter Leonardo's den, where he kept, as Giorgio Vasari in "Lives of the Artists", describes: "a number of green and other kinds of lizards, crickets, serpents, butterflies, locusts, hats, and various strange creatures of this nature". Leonardo's clients were often dissatisfied with his glacial pace, lack of professional discipline, and inability to conclude his assignments. He was frequently involved in litigation. The Cofraternity of the Immaculate Conception sued him when he failed to produce the Virgin on the Rocks, an altarpiece they commissioned from him in 1483. The court proceedings lasted 10 years. The head of Jesus in "The Last Supper" was left blank because Leonardo did not dare to paint a human model, nor did he trust his imagination sufficiently. Leonardo worked four years on the Mona Lisa but never completed it, either. He carried it with him wherever he went. Leonardo's terra cota model for a colossal bronze sculpture of the father of his benefactor and employer, Ludovico Sforza, was used for target practice by invading French soldiers in 1499. The metal which was supposed to go into this work of art was molded into cannon balls. Leonardo was a member of the commission which deliberated where to place Michelangelo's magnificent statue of David. His cartographic work was so ahead of its time, that the express highway from Florence to the sea - built in the 20th century - follows precisely the route of a canal he envisioned. His scientific investigations - in anatomy, hydraulics, mechanics, ornithology, botany - are considered valuable to this very day. Bill Gates owns some his notebooks containing scientific data and observations (known as the Codex Hammer). But Leonardo's loyalties were fickle. He switched sides to the conquering French and in 1506 returned to Milan to work for its French governor, Charles D'Amboise. Later, he became court painter for King Louis XII of France who, at the time, resided in Milan. In 1516, he relocated to France, to serve King Francis I and there he died. Leonardo summed up the lessons of his art in a series of missives to his students, probably in Milan. These were later (1542) collected by his close associate, Francesco Melzi, as "A Treatise on Painting" and published in print (1651, 1817).