Jan van der Vaart or Jan van der Vaardt was a Dutch painter and draughtsman of portraits and trompe-l'œil paintings and a mezzotint artist, active in England for most of his career. He was an art restorer and art collector. Van der Vaart was born in Haarlem. Van der Vaart is documented from 1674 onwards in London. Here he worked in the workshop of another Dutch immigrant, Willem Wissing, a pupil and former collaborator of the court portrait painter Sir Peter Lely. Van der Vaart painted landscapes in the portraits of Wissing. After Wissing's death in 1687, van der Vaart continued his workshop, he collaborated on occasion with the German-born painter Johann Kerseboom. In 1713 van der Vaart built a house in Covent Garden, he stopped painting and confined himself to the restoration of paintings because of his deteriorating eyesight. He died in London, a bachelor, his nephew Arnold continued his restoration business, he was the teacher of the famous English mezzotint engraver John Smith. He was a versatile painter and painted in a wide range of genres including flower still lifes, religious paintings, history paintings, landscapes and trompe-l'oeil still lives.
According to Walpole he painted a trompe l'oeil of a violin on a door at Chatsworth House. He is known for his portraits and landscapes. A number of van der Vaard's portraits were engraved in mezzotint by Bernard Lens for the print publisher Edward Cooper. Van der Vaart was himself one of the earliest practitioners of mezzotint in England and produced many prints after portraits made by portrait artists like Sir Peter Lely, Willem Wissing etc. Media related to Jan van der Vaart at Wikimedia Commons
The mononuclear spot test or monospot test, a form of the heterophile antibody test, is a rapid test for infectious mononucleosis due to Epstein–Barr virus. It is an improvement on the Paul–Bunnell test; the test is specific for heterophile antibodies produced by the human immune system in response to EBV infection. Commercially available test kits are 70–92% sensitive and 96–100% specific, with a lower sensitivity in the first two weeks after clinical symptoms begin; the United States Center for Disease Control deems the monospot test to not be useful. It is indicated as a confirmatory test when a physician suspects EBV in the presence of clinical features such as fever, pharyngitis, tender lymphadenopathy and splenomegaly. In the case of delayed or absent seroconversion, an immunofluorescence test could be used if the diagnosis is in doubt, it has the following characteristics: VCAs of the IgM class, antibodies to EBV early antigen, absent antibodies to EBV nuclear antigen One source states that the specificity of the test is high 100%, Another source states that a number of other conditions can cause false positives.
However, a false positive heterophile antibody test may result from systemic lupus erythematosus, rubella and leukemia. However, the sensitivity is only moderate, so a negative test does not exclude EBV; this lack of sensitivity is the case in young children, many of whom will not produce the heterophile antibody at any stage and thus have a false negative test result. It will not be positive during the 4–6 week incubation period before the onset of symptoms; the highest amount of heterophile antibodies occurs 2 to 5 weeks after the onset of symptoms. If positive, it will remain so for at least six weeks. An elevated heterophile antibody level may persist up to 1 year; the test relies on the agglutination of horse erythrocytes by heterophile antibodies in patient serum. Heterophile means. Heterophile can mean that it is an antibody that reacts with antigens other than the antigen that stimulated it. A 20% suspension of horse red cells is used in an isotonic 3–8% sodium citrate formulation. One drop of the patient’s serum to be tested is mixed on an opal glass slide with one drop of a particulate suspension of guinea-pig kidney stroma, a suspension of ox red cell stroma.
Ten micro liters of the horse red cell suspension are added and mixed with each drop of adsorbed serum. The mixture is left undisturbed for one minute. Examine for the presence or absence of red cell agglutination. If stronger with the sera adsorbed with guinea-pig kidney, the test is positive. If stronger with the sera adsorbed with ox red cell stroma, the test is negative. If agglutination is absent in both mixtures, the test is negative. A known'positive' and'negative' control serum is tested with each batch of test sera
The Meagre Company, or The company of Captain Reinier Reael and Lieutenant Cornelis Michielsz Blaeuw, refers to the only militia group portrait, or schutterstuk, painted by Frans Hals outside of Haarlem, today is in the collection of the Amsterdam Museum, on loan to the Rijksmuseum, where it is considered one of its main attractions of the Honor Gallery. Hals was unhappy about commuting to Amsterdam to work on the painting and, unlike his previous group portraits, was unable to deliver it on time; the sitters contracted Pieter Codde to finish the work. Hals was contracted in 1633, after the favorable reception of his previous militia group portrait, The Officers of the St Adrian Militia Company in 1633, in which all ensigns are holding flags and all officers are holding their weapons; the sergeants were shown, holding halberds to differentiate them from officers with spontoons. Hals seems to have intended an Amsterdam version of the same painting, beginning on the left with a smiling flag bearer wearing a flamboyant cut-sleeve jacket with lace and holding a flag in the color of his sash.
Though it is impossible to tell on which side of the canvas Hals began painting, the light falls onto the figures from the left in the "standard" Hals tradition and this is where the most important figures are situated within the painting. Since each sitter paid for his own portrait, it is presumed that Hals began with the most important sitters in order to "sell" canvas room to other paying officers. Whether or not Hals did in fact start on the left or drew a sketch of the entire group at once, the flag bearer on the left in this painting has been painted in a remarkably flamboyant way from the tip of his hat to the toe of his boots; this was to prove to the decision makers in Amsterdam that Hals was capable of painting a schutterstuk in the "Amsterdam style", which included the entire figure. In Haarlem, the civic guards were traditionally portrayed in the kniestuk style of being "cut off at the knee" in three-quarter length portraits; the flag bearer is Nicolaes van Bambeeck. Seated next to him are Captain Reael, with hat and commander's staff, Lieutenant Cornelis Michielsz Blaeuw and holding a spontoon.
The further to the right, the less the two paintings resemble each other. In 1636 Hals was called to Amsterdam to finish the painting, but he refused, offering to receive the sitters in his Haarlem studio with assurances that they would not need to sit long, his offer was refused and Codde was hired to finish the piece. Because the men are thinner than the men portrayed in other Amsterdam schutterstukken hanging near this painting, the piece was nicknamed the "meagre company". Besides the ensign and the seated men, the names of the other officers are unknown today; the post-impressionist painter Vincent van Gogh was inspired by the painting, which he saw when he paid a visit to the Night Watch in the newly opened Rijksmuseum in 1885. He sent an enthusiastic letter about it to his brother Theo: I don’t know whether you remember that to the left of the Night watch, in other words as a pendant to the Syndics, there’s a painting — it was unknown to me until now — by Frans Hals and P. Codde, 20 or so officers full length.
Have you noticed it??? In itself, that painting alone makes the trip to Amsterdam well worth while for a colourist. There’s a figure in it, the figure of the standard-bearer in the extreme left corner, right up against the frame; that figure is in grey from top to toe, let’s call it pearl grey, — of a singular neutral tone — obtained with orange and blue mixed so that they neutralize each other — by varying this basic colour in itself — by making it a little lighter here, a little darker there, the whole figure is as it were painted with one and the same grey. But the leather shoes are a different material from the leggings, which are different from the folds of the breeches, which are different from the doublet — expressing different materials different in colour one from another, still all one family of grey — but wait! Into that grey he now introduces orange -- and some white; the doublet has satin ribbons of a divine soft blue. Sash and flag orange — a white collar. Orange, blue, as the national colours were then.
Orange and blue next to each other, that most glorious spectrum — on a ground of grey judiciously mixed by uniting just those two, let me call them poles of electricity so that they obliterate each other, a white against that grey. Further carried through in that painting — other orange spectrums against a different blue, further the most glorious blacks against the most glorious whites — the heads — some twenty — sparkling with spirit and life, how they’re done! and what colour! the superb appearance of all those fellows, full length. But that orange, blue chap in the left corner — — …… I’ve seen a more divinely beautiful figure — — it’s something marvellous. Delacroix would have adored it — just adored it to the utmost; the painting hung with others in the old Archer's meeting hall called the "Voetboogdoelen", located on the Singel. It was located there until the building was deconstructed to build the library of the University of Amsterdam; the group paintings that hung in this hall have been since transferred to the Amsterdam Museum, except for this one and a one by Bartholomeus van der Helst, which are on permanent loan to the Rijksmuseum.
The'Meagre Company' hangs across from its successor, the next militia group portrait to be painted in Amsterdam, Van der Helst's The Company of Roelof Bicker and lieutenant Jan Michielsz Blaeuw, completed in 1639. These paintings are both hung near Rembrandt's The Night Watch, completed well over a decade after