In knot theory, there are several competing notions of the quantity writhe, or Wr. In one sense, it is purely a property of an oriented link diagram and assumes integer values. In another sense, it is a quantity that describes the amount of "coiling" of a mathematical knot (or any closed, simple curve) in three-dimensional space and assumes real numbers as values. In both cases, writhe is a geometric quantity, meaning that while deforming a curve (or diagram) in such a way that does not change its topology, one may still change its writhe.
Writhe of link diagrams
In knot theory, the writhe is a property of an oriented link diagram. The writhe is the total number of positive crossings minus the total number of negative crossings.
A direction is assigned to the link at a point in each component and this direction is followed all the way around each component. If as you travel along a link component and cross over a crossing, the strand underneath goes from right to left, the crossing is positive; if the lower strand goes from left to right, the crossing is negative. One way of remembering this is to use a variation of the right-hand rule.
DNA supercoiling refers to the over- or under-winding of a DNA strand, and is an expression of the strain on that strand. Supercoiling is important in a number of biological processes, such as compacting DNA, and by regulating access to the genetic code, DNA supercoiling strongly affects DNA metabolism and possibly gene expression. Additionally, certain enzymes such as topoisomerases are able to change DNA topology to facilitate functions such as DNA replication or transcription. Mathematical expressions are used to describe supercoiling by comparing different coiled states to relaxed B-form DNA.
Overview
In a "relaxed" double-helical segment of B-DNA, the two strands twist around the helical axis once every 10.4–10.5 base pairs of sequence. Adding or subtracting twists, as some enzymes can do, imposes strain. If a DNA segment under twist strain were closed into a circle by joining its two ends and then allowed to move freely, the circular DNA would contort into a new shape, such as a simple figure-eight. Such a contortion is a supercoil. The noun form "supercoil" is often used in the context of DNA topology.
Everyone seems to be servin' for Satan, guess I will too What a joke, you make me laugh till I turn blue Anyone tale goes out to there what a manly lookin' crew I don't think I'll tease my hair, I'd rather sit here teasing you Close your eyes, my snakes down on the floor Out you go and in come one hundred more I seem to lost my cowboy boots with green fringe runnin' down the side My soul machine has made me green 'cause my jeans didn't turn out tight And all these ruins I turn for you, you keep my livin' alive Your smile over weighs the miles and your kiss makes it worth the ride Close your eyes, my snakes down on the floor
SabrinaCarpenter posed up a storm in a number of lingerie looks - despite sparking complaints over her 'inappropriate' shows ... 'Said your not in my time zone, but you wanna be,' she wrote as the caption ... Sabrina Carpenter. .
The victim can be seen grimacing while the large reptile is latched on to his groin area, apparently sinking its teeth through his trousers and on to his penis, in the forests of Pantanal, Brazil... .
This is the agonising moment a man writhed in pain after a snake bit his penis and refused to let go in unsettling scenes from Brazil. The victim was seen in viral video grimacing on the ground as a friend filmed from a cautious distance ... .
The actor made it through his own nomination but was then ushered to an ambulance – an extraordinary performance from an apparently limitless talent. Awards season is hard for everyone ...It’s hard for journalists, who have to cover the awards ... ....
The Irish actor, 48, was attending the star-studded ceremony in Los Angeles when he suddenly found himself “writhing in agony” ... He continued to Variety. “I was in the back [of the room]…writhing around in agony ... “That’s too much.
Awards season is hard for everyone ...It’s hard for journalists, who have to cover the awards ... Indeed, things got so bad that Scott had to leave during Dern’s speech, and found himself “in the back [of the room] … writhing around in agony” ... Read more ... .
Civilization 7 is a game that has a lot of layers for the player to peel away. Some of these layers are jumbled up in a messy UI, while others act as hidden mechanics that the player can slowly understand as they continue playing the game ... .
