Euglenozoa
The Euglenozoa are a large phylum of flagellate protists.
They are part of the wastebasket taxon known as the Protozoa, which contained many obviously different protists.
Euglenozoa include a variety of common free-living species, and some important parasites, of which a few infect humans. There are two main subgroups, the euglenids and kinetoplastids. Euglenozoa are unicellular, mostly around 1540 µm in size, although some euglenids get up to 500 µm long.
Most euglenozoa have two flagella, parallel to one another in an pocket-like structure. In some there is a cytostome or mouth, used to ingest bacteria or other small organisms. This is supported by a microtubule from the flagellar bases; two other tubules support the dorsal and ventral surfaces of the cell.
Some other euglenozoa feed through the absorption, and many euglenids possess chloroplasts and so obtain energy through photosynthesis. These chloroplasts are surrounded by three membranes and contain chlorophylls "A" and "C", along with other pigments, so are probably evolved from those of a captured green alga. Reproduction occurs exclusively through cell division. During mitosis, the nuclear membrane remains intact, and the spindle microtubules form inside of it.
The group is characterized by the ultrastructure of the flagella. In addition to the normal supporting microtubules, each contains a rod (called "paraxonemal"), which has a tubular structure in one flagellum and a latticed structure in the other.
The euglenozoa are generally accepted as monophyletic. They are related to Percolozoa; the two share mitochondria with disk-shaped compartments, which only occurs in a few other groups.
Both probably belong to a larger group of eukaryotes called the Excavata. This grouping, though, has been challenged.
Commodore 64
The Commodore 64 was a bestselling, 8-bit home computer from the 1980s. It was created by Commodore International, and it entered the market in 1982. Around 17 million units are believed to have been sold. The Commodore 64 is often credited with making personal computers popular amongst the masses. This quality sparked comparisons with the Ford Model T. The Commodore 64 was offered at relatively low prices, and was available in malls, department stores, and toy stores instead of solely in the shops of authorized dealers.
Kinetoplastid
The kinetoplastids are a group of single-cell flagellate eukaryotes. They include a number of parasites responsible for serious diseases in humans and other animals. There are also forms found in soil and aquatic environments. They are members of the phylum Euglenozoa.
Their main distinguishing feature is the presence of a kinetoplast, a DNA-containing granule inside the single mitochondrion at the base of the cell's flagella (the basal body).
The kinetoplastids were first defined by Honigberg in 1961 as the flagellate order Kinetoplastida. They are traditionally divided into the biflagellate Bodonidae and uniflagellate Trypanosomatidae.
The Trypanosomatidae includes several genera which are exclusively parasitic. "Trypanosoma brucei" causes Sleeping sickness; "Trypanosoma cruzi" causes Chagas disease, "Leishmania" causes leishmaniasis, "Crithidia" is parasitic on insects, and "Cryptobia" is an ectoparasite on the gills of fish.
"Bodo" is typical of the free-living Bodonids, and includes various species which feed on bacteria.
Captain George K. H. Coussmaker
Captain George K. H. Coussmaker (1782) is an oil painting by Joshua Reynolds. Coussmaker was born in London in 1759 to Evert and Mary Coussmaker. He entered the military in 1776. He was promoted several times. He never saw active service. He retired in 1795. He married Catherine Southwell in 1790. They had two children, George and Sophia (later, the Baroness de Clifford). He died in 1801.
Coussmaker sat for Reynolds 21 times and his horse 8 times between February 9 and April 16. Reynolds was paid 205 pounds. Another 10 guineas paid for the frame. The portrait remained with Coussmaker and his descendants until 1884. It was then sold to William K. Vanderbilt. Vanderbilt bequeathed to the Metropolitan Museum of Art in 1920. Museum curators describe the picture as "an exceptionally fine work ... The composition is complex and the whole vigorously painted."
Pet Shop Boys
Pet Shop Boys are a British synthpop duo: Neil Tennant and Chris Lowe. They formed in London in 1981 after they met in an electronics shop. They have sold 50 million records and are the most successful British music duo of all time. They have won three Brit Awards. They have been nominated for seven Grammy Awards. In 1984 their first single "West End Girls" was released. It reached number one in the UK and US.
Nicole
Nicole is a female given name of Greek origin. It means "victorious people". It is the French female version of the boy's name "Nicholas". There are many variants for this female name. Famous persons going by the name include Nicole Sullivan and Nicole Kidman. The name is being used for tropical storms or hurricanes in Atlantic Basin.
The Dancing Class
The Dancing Class is an oil painting by Edgar Degas painted about 1870. It was the first of his ballet pictures. It depicts a dance class at the Paris Opéra. When he painted this picture, Degas did not yet have privileges to go backstage at the Opéra. In the late 1870s, Degas said, "I have done [painted] so many of these dance examinations without having seen them that I am a little ashamed of it."
Joséphine Gaujelin (or Gozelin) is the dancer in the center of the picture. She waits for the starting note from the ballet master. The watering can (to wet down the rosin on the floor), the top hat as music holder, and the empty violin case are props that Degas would continue to use in his ballet pictures. Degas would re-use the poses in this picture many times.
Diastereomer
Diastereomers (also called diastereoisomers) are stereoisomers which are not enantiomers. They are molecules which have the same atoms and bonds but different stereochemistry in at least one, but not all, of their chiral centres. Diastereomers can have very different properties even though they look similar. This is different from enantiomers, that have exactly the same properties except when in a chiral environment like the human body.
Every chiral centre in a molecule has two possible ways of putting the groups in space. With only one chiral centre, there are two enantiomers. With two chiral centres, you can form 4 different isomers. When all chiral centres are changed at the same time, two pairs of enantiomers are formed. When only one chiral centre is changed at a time, sets of diastereoisomers are formed. With more chiral centres the possibilities are many more.
Diastereoisomers which are different at only one of more chiral centres are called epimers. For example, -Threose and -Erythrose (see picture) are diastereomers because they are different at only one of two chiral centres. Because of this they can also be called epimers.
Rate-determining step
The rate-determining step is the step for which the transition state has the highest energy. It is the slowest step within a chemical reaction. It can be thought of as the most difficult step to go through. It is also the step that must be used to calculate the activation energy.
Knowing which step is rate-determining is very important when studying a reaction mechanism. This is because if this step is changed the reaction can go much faster. This can be done for example by using a different reagent or changing the temperature or pressure. Changing the conditions for any other step of the mechanism will not change the overall speed of the reaction at all.
In the rate equation, which is an equation to calculate the speed of the reaction from the concentration of molecules, usually the only step that is important is the rate-determining one.
Japanese Footbridge