Cylinder (gastropod)

Cylinder is a subgenus of sea snails, marine gastropod mollusks in the genus Conus, in the family Conidae, the cone snails and their allies. In the new classification of the family Conidae by Puillandre N. Duda T. F. Meyer C. Olivera B. M. & Bouchet P. Cylinder has become a subgenus of Conus: Conus Petuch & Sargent, 2012 represented as Conus Thiele, 1929; the same study found Cylinder to be polyphyletic, but morphologically consistent corresponding to grades. Conus ammiralis, Conus canonicus and Conus dalli cluster with the type species Conus textile, the others form a separate clade; the Tucker & Tenorio 2009 taxonomy distinguishes Cylinder from Conus in the following ways: Genus Conus Linnaeus, 1758Shell characters The basic shell shape is conical to elongated conical, has a deep anal notch on the shoulder, a smooth periostracum and a small operculum. The shoulder of the shell is nodulose and the protoconch is multispiral. Markings include the presence of tents except for black or white color variants, with the absence of spiral lines of minute tents and textile bars.

Radular tooth The radula has an elongated anterior section with serrations and a large exposed terminating cusp, a non-obvious waist, blade is either small or absent and has a short barb, lacks a basal spur. Geographical distribution These species are found in the Indo-Pacific region. Feeding habits These species eat other gastropods including cones. Subgenus Cylinder Montfort, 1810Shell characters The shell is ovate to elongated in shape; the protoconch is multispiral, the spire is conical to convex in shape. The anal notch is deep; the shell is conspicuously ornamented with rows of tents or textile bars. The periostracum is smooth, the operculum is small. Radular tooth The anterior section of the radula is more elongated than the posterior section; the waist is not obvious. A basal spur is absent, the barb is short; the blade and a terminating cusp are present. Geographical distribution All but one species in this genus are found in the Indo-Pacific region. Feeding habits These species are molluscivorous.

This list of species is based on the information in the World Register of Marine Species list. Species within the genus Cylinder include: Cylinder abbas: synonym of Conus abbas Hwass in Bruguière, 1792 Cylinder ammiralis Linnaeus, 1758: synonym of Conus ammiralis Linnaeus, 1758, represented as Conus ammiralis Linnaeus, 1758 Cylinder aureus: synonym of Conus aureus Hwass in Bruguière, 1792 Cylinder barbieri: synonym of Conus barbieri G. Raybaudi Massilia, 1995 Cylinder bengalensis: synonym of Conus bengalensis Cylinder biancae: synonym of Conus biancae Bozzetti, 2010 Cylinder canonicus: synonym of Conus canonicus Hwass in Bruguière, 1792 Cylinder dalli: synonym of Conus dalli Stearns, 1873 Cylinder dondani: synonym of Conus dondani Kosuge, 1981 Cylinder erythrostoma: synonym of Miniaceoliva miniacea Cylinder gloriamaris: synonym of Conus gloriamaris Chemnitz, 1777 Cylinder glorioceanus: synonym of Conus glorioceanus Poppe & Tagaro, 2009 Cylinder legatus: synonym of Conus legatus Lamarck, 1810 Cylinder nodulosus: synonym of Conus nodulosus G.

B. Sowerby II, 1864 Cylinder pacificus: synonym of Conus pacificus Moolenbeek & Röckel, 1996 Cylinder paulucciae: synonym of Cylinder aureus paulucciae represented as Conus aureus paulucciae G. B. Sowerby III, 1887 Cylinder priscai Bozzetti, 2012: synonym of Conus priscai Bozzetti, 2012 represented as Conus priscai Cylinder retifer: synonym of Conus retifer Menke, 1829 Cylinder scottjordani: synonym of Conus scottjordani represented as Conus scottjordani Cylinder tagaroae Limpalaër & Monnier, 2013: synonym of Conus tagaroae represented as Conus tagaroae Cylinder telatus: synonym of Conus telatus Reeve, 1848 Cylinder textile: synonym of Conus textile Linnaeus, 1758 Cylinder victoriae: synonym of Conus victoriae Reeve, 1843 Kohn A. A.. Chronological Taxonomy of Conus, 1758-1840". Smithsonian Institution Press and London. Monteiro A.. The Cone Collector 1: 1-28. Berschauer D.. Technology and the Fall of the Mono-Generic Family The Cone Collector 15: pp. 51-54 Puillandre N. Meyer C. P. Bouchet P. and Olivera B.

M. Genetic divergence and geographical variation in the deep-water Conus orbignyi complex, Zoologica Scripta 40 350-363. To World Register of Marine Species Gastropods.com: Conidae setting forth the genera recognized therein

Cylinder (locomotive)

The cylinder is the power-producing element of the steam engine powering a steam locomotive. The cylinder is made pressure-tight with a piston. Cylinders were cast in cast iron and in steel; the cylinder casting includes other features such as mounting feet. The last big American locomotives incorporated the cylinders as part of huge one-piece steel castings that were the main frame of the locomotive. Renewable wearing surfaces were provided by cast-iron bushings; the way the valve controlled the steam entering and leaving the cylinder was known as steam distribution and shown by the shape of the indicator diagram. What happened to the steam inside the cylinder was assessed separately from what happened in the boiler and how much friction the moving machinery had to cope with; this assessment was known as "engine performance" or "cylinder performance". The cylinder performance, together with the boiler and machinery performance, established the efficiency of the complete locomotive; the pressure of the steam in the cylinder was measured as the piston moved and the power moving the piston was calculated and known as cylinder power.

The forces produced in the cylinder moved the train but were damaging to the structure which held the cylinders in place. Bolted joints came loose, cylinder castings and frames cracked and reduced the availability of the locomotive. Cylinders may be arranged in several different ways. On early locomotives, such as Puffing Billy, the cylinders were set vertically and the motion was transmitted through beams, as in a beam engine; the next stage, for example Stephenson's Rocket, was to drive the wheels directly from steeply inclined cylinders placed at the back of the locomotive. Direct drive became the standard arrangement, but the cylinders were moved to the front and placed either horizontal or nearly horizontal; the front-mounted cylinders could be placed either outside. Examples: Inside cylinders, Planet locomotive Outside cylinders, GNR Stirling 4-2-2In the 19th and early 20th centuries, inside cylinders were used in the UK, but outside cylinders were more common in Continental Europe and the United States.

The reason for this difference is unclear. From about 1920, outside cylinders became more common in the UK but many inside-cylinder engines continued to be built. Inside cylinders give a more stable ride with less yaw or "nosing" but access for maintenance is more difficult; some designers used inside cylinders for aesthetic reasons. The demand for more power led to the development of engines with four cylinders. Examples: Three cylinders, SR Class V, LNER Class A4, Merchant Navy class Four Cylinders, LMS Princess Royal Class, LMS Coronation Class, GWR Castle Class On a two-cylinder engine the cranks, whether inside or outside, are set at 90 degrees; as the cylinders are double-acting this gives four impulses per revolution and ensures that there are no dead centres. On a three-cylinder engine, two arrangements are possible: cranks set to give six spaced impulses per revolution – the usual arrangement. If the three cylinder axes are parallel, the cranks will be 120 degrees apart, but if the centre cylinder does not drive the leading driving axle, it will be inclined, the inside crank will be correspondingly shifted from 120 degrees.

For a given tractive effort and adhesion factor, a three-cylinder locomotive of this design will be less prone to wheelslip when starting than a 2-cylinder locomotive. Outside cranks set at 90 degrees, inside crank set at 135 degrees, giving six unequally spaced impulses per revolution; this arrangement was sometimes used on three-cylinder compound locomotives which used the outside cylinders for starting. This will give evenly spaced exhausts. Two arrangements are possible on a four-cylinder engine: all four cranks set at 90 degrees. With this arrangement the cylinders act in pairs, so there are four impulses per revolution, as with a two-cylinder engine. Most four-cylinder engines are of this type, it is cheaper and simpler to use only one set of valve gear on each side of the locomotive and to operate the second cylinder on that side by means of a rocking shaft from the first cylinder's valve spindle since the required valve events at the second cylinder are a mirror image of the first cylinder.

Pairs of cranks set at 90 degrees with the inside pair set at 45 degrees to the outside pair. This gives eight impulses per revolution, it increases weight and complexity, by requiring four sets of valve gear, but gives smoother torque and reduces the risk of slipping. This was unusual in British practice but was used on the SR Lord Nelson class; such locomotives are distinguished by their exhaust beats, which occur at twice the frequency of a normal 2- or 4-cylinder engine. The valve chests or steam chests which contain the slide valves or piston valves may be located in various positions. If the cylinders are small, the valve chests may be located between the cylinders. For larger cylinders the valve chests are on top of the cylinders but, in early locomotives, they were sometimes underneath the cylinders; the valve chests are on top of the cylinders but, in older locomotives, the valve chests were sometimes located alongside the cylinders and inserted through slots in the frames. This meant that, while the cylinders were outside, the valves were inside a

Cylinder (firearms)

In firearms, the cylinder is the cylindrical, rotating part of a revolver containing multiple chambers. The cylinder revolves around a central axis in the revolver to bring each individual chamber into alignment with the barrel for firing; each time the gun is cocked, the cylinder indexes by one chamber. Cylinders hold six cartridges, but some small-frame revolvers hold only 5 cartridges, due to the smaller overall size of the gun and small available space; the Nagant M1895 revolver has a 7-shot cylinder, the Webley-Fosbery Automatic Revolver has an 8-shot cylinder in.38 caliber, the LeMat Revolver has a 9-shot cylinder. Several models of.22 rimfire-caliber revolvers have cylinders holding 10 rounds. As a rule, cylinders are not designed to be detached from the firearm. Rapid reloading is instead facilitated by the use of a speedloader or moon clip, although these work only on break-top and swing-out cylinder revolvers, for obvious reasons; the first generation of cartridge revolvers were converted caplock designs.

In many of these, the pin on which the cylinder revolved was removed, the cylinder was taken from the gun for loading. Models used a loading gate at the rear of the cylinder that allowed one cartridge at a time to be inserted for loading, while a rod under the barrel could be pressed rearward to eject the fired case. Most revolvers using this method of loading are single-action revolvers. Oddly, the loading gate on the original Colt designs is on the right side, which may favor left-handed users; this was done because these pistols were intended for use with cavalry, it was intended that the revolver and the reins would be held in the left hand while the right hand was free to load the cartridges. Since the cylinder in these revolvers is attached at the front and rear of the frame, since the frame is full thickness all the way around, fixed-cylinder revolvers are inherently strong designs; because of this, many modern large-caliber hunting revolvers tend to be based on the fixed-cylinder design.

Fixed-cylinder revolvers can fire the strongest and most powerful cartridges, but at the price of being the slowest to load and reload and they cannot use speedloaders or moon clips for loading, as only one chamber is exposed at a time to the loading gate. The next method used for loading and unloading cartridge revolvers was the top break design. In a top-break revolver, the frame is hinged at the bottom front of the cylinder. Releasing the lock and pushing the barrel down brings the cylinder up, which exposes the rear of the cylinder for reloading. In most top-break revolvers, the act of pivoting the barrel and cylinder operates an extractor that pushes the cartridges in the chambers back far enough that they will fall free, or can be removed easily. Fresh rounds are inserted into the cylinder, either one at a time or all at once with either a speedloader or a moon clip; the barrel and cylinder are rotated back and locked in place, the revolver is ready to fire. Since the frame is in two parts, held together by a latch on the top rear of the cylinder, top-break revolvers cannot handle high pressure or "magnum"-type rounds.

Top-break designs are extinct in the world of firearms, but are still found in airguns. One of the most famous "break-top" revolvers is the Webley service revolver, used by the British military from 1889 to 1963; the American outlaw Jesse James used the 19th century Schofield Model 3 break-top revolver, the Russian Empire issued the similar.44 Russian calibre Smith & Wesson No. 3 Revolver from 1870 until 1895. The most modern method of loading and unloading a revolver is by means of the swing-out cylinder; the cylinder is mounted on a pivot, coaxial with the chambers, the cylinder swings out and down. An extractor is operated by a rod projecting from the front of the cylinder assembly; when pressed, it will push all fired rounds free simultaneously. The cylinder may be loaded, singly or again with a speedloader and latched in place; the pivoting part that supports the cylinder is called the crane. Using the method portrayed in movies and television of flipping the cylinder open and closed with a flick of the wrist can in fact cause the crane to bend over time, throwing the cylinder out of alignment with the barrel.

Lack of alignment between chamber and barrel is a dangerous condition, as it can impede the bullet's transition from chamber to barrel. This gives rise to higher pressures in the chamber, bullet damage, the potential for an explosion if the bullet becomes stuck; the shock of firing can exert a great deal of stress on the crane, as in most designs the cylinder is only held closed at one point, the rear of the cylinder. Stronger designs, such as the Ruger Super Redhawk, use a lock in the crane as well as the lock at the rear of the cylinder; this latch provides a more secure bond between cylinder and frame, allows the use of larger, more powerful cartridges. Swing-out cylinders are rather strong, but not as strong as fixed cylinders, great care must be taken with the cylinder when loading, so as not to damage the crane. Firearm cylinders were first developed in the 16th century and, over time, had

Cylindera

Cylindera is a genus of ground beetles native to the Palearctic, the Near East and northern Africa. It was a result of the breakup of the Cicindela genus, the status of Cylindera as a genus or a subgenus of the genus Cicindela is in dispute. List of Cylindera species

Cartesian product

In set theory, a Cartesian product is a mathematical operation that returns a set from multiple sets. That is, for sets A and B, the Cartesian product A × B is the set of all ordered pairs where a ∈ A and b ∈ B. Products can be specified using e.g.. A × B =. A table can be created by taking the Cartesian product of a set of columns. If the Cartesian product rows × columns is taken, the cells of the table contain ordered pairs of the form. More a Cartesian product of n sets known as an n-fold Cartesian product, can be represented by an array of n dimensions, where each element is an n-tuple. An ordered pair is a couple; the Cartesian product is named after René Descartes, whose formulation of analytic geometry gave rise to the concept, further generalized in terms of direct product. An illustrative example is the standard 52-card deck; the standard playing card ranks form a 13-element set. The card suits form a four-element set; the Cartesian product of these sets returns a 52-element set consisting of 52 ordered pairs, which correspond to all 52 possible playing cards.

Ranks × Suits returns a set of the form. Suits × Ranks returns a set of the form. Both sets are distinct disjoint; the main historical example is the Cartesian plane in analytic geometry. In order to represent geometrical shapes in a numerical way and extract numerical information from shapes' numerical representations, René Descartes assigned to each point in the plane a pair of real numbers, called its coordinates; such a pair's first and second components are called its x and y coordinates, respectively. The set of all such pairs is thus assigned to the set of all points in the plane. A formal definition of the Cartesian product from set-theoretical principles follows from a definition of ordered pair; the most common definition of ordered pairs, the Kuratowski definition, is =. Under this definition, is an element of P, X × Y is a subset of that set, where P represents the power set operator. Therefore, the existence of the Cartesian product of any two sets in ZFC follows from the axioms of pairing, power set, specification.

Since functions are defined as a special case of relations, relations are defined as subsets of the Cartesian product, the definition of the two-set Cartesian product is prior to most other definitions. Let A, B, C, D be sets; the Cartesian product A × B is not commutative, A × B ≠ B × A, because the ordered pairs are reversed unless at least one of the following conditions is satisfied: A is equal to B, or A or B is the empty set. For example: A =. × C ≠ A × If for example A = × A = ≠ = A ×. The Cartesian product behaves nicely with respect to intersections. × = ∩. × ≠ ∪ In fact, we have that: ∪ = ∪ ∪ [ ( B

Cylinder

A cylinder has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. It is the idealized version of a solid physical tin can having lids on bottom; this traditional view is still used in elementary treatments of geometry, but the advanced mathematical viewpoint has shifted to the infinite curvilinear surface and this is how a cylinder is now defined in various modern branches of geometry and topology. The shift in the basic meaning has created some ambiguity with terminology, it is hoped that context makes the meaning clear. In this article both points of view are presented and distinguished by referring to solid cylinders and cylindrical surfaces, but keep in mind that in the literature the unadorned term cylinder could refer to either of these or to an more specialized object, the right circular cylinder; the definitions and results in this section are taken from the 1913 text and Solid Geometry by George Wentworth and David Eugene Smith. A cylindrical surface is a surface consisting of all the points on all the lines which are parallel to a given line and which pass through a fixed plane curve in a plane not parallel to the given line.

Any line in this family of parallel lines is called an element of the cylindrical surface. From a kinematics point of view, given a plane curve, called the directrix, a cylindrical surface is that surface traced out by a line, called the generatrix, not in the plane of the directrix, moving parallel to itself and always passing through the directrix. Any particular position of the generatrix is an element of the cylindrical surface. A solid bounded by a cylindrical surface and two parallel planes is called a cylinder; the line segments determined by an element of the cylindrical surface between the two parallel planes is called an element of the cylinder. All the elements of a cylinder have equal lengths; the region bounded by the cylindrical surface in either of the parallel planes is called a base of the cylinder. The two bases of a cylinder are congruent figures. If the elements of the cylinder are perpendicular to the planes containing the bases, the cylinder is a right cylinder, otherwise it is called an oblique cylinder.

If the bases are disks the cylinder is called a circular cylinder. In some elementary treatments, a cylinder always means a circular cylinder; the height of a cylinder is the perpendicular distance between its bases. The cylinder obtained by rotating a line segment about a fixed line that it is parallel to is a cylinder of revolution. A cylinder of revolution is a right circular cylinder; the height of a cylinder of revolution is the length of the generating line segment. The line that the segment is revolved about is called the axis of the cylinder and it passes through the centers of the two bases; the bare term cylinder refers to a solid cylinder with circular ends perpendicular to the axis, that is, a right circular cylinder, as shown in the figure. The cylindrical surface without the ends is called an open cylinder; the formulae for the surface area and the volume of a right circular cylinder have been known from early antiquity. A right circular cylinder can be thought of as the solid of revolution generated by rotating a rectangle about one of its sides.

These cylinders are used in an integration technique for obtaining volumes of solids of revolution. A cylindric section is the intersection of a cylinder's surface with a plane, they are, in general and are special types of plane sections. The cylindric section by a plane that contains two elements of a cylinder is a parallelogram; such a cylindric section of a right cylinder is a rectangle. A cylindric section in which the intersecting plane intersects and is perpendicular to all the elements of the cylinder is called a right section. If a right section of a cylinder is a circle the cylinder is a circular cylinder. In more generality, if a right section of a cylinder is a conic section the solid cylinder is said to be parabolic, elliptic or hyperbolic respectively. For a right circular cylinder, there are several ways. First, consider planes that intersect a base in at most one point. A plane is tangent to the cylinder; the right sections are circles and all other planes intersect the cylindrical surface in an ellipse.

If a plane intersects a base of the cylinder in two points the line segment joining these points is part of the cylindric section. If such a plane contains two elements, it has a rectangle as a cylindric section, otherwise the sides of the cylindric section are portions of an ellipse. If a plane contains more than two points of a base, it contains the entire base and the cylindric section is a circle. In the case of a right circular cylinder with a cylindric section, an ellipse, the eccentricity e of the cylindric section and semi-major axis a of the cylindric section depend on the radius of the cylinder r and the angle α between the secant plane and cylinder axis, in the following way: e = cos α, a = r sin α. If the base of a circular cylinder has a radius r and the cylinder has height h its volume is given by V = πr2h; this formula holds. This formula may be established by using Cavalieri's principle. In more generality, by the same principle, the volume of an

Eyeglass prescription

An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist or ophthalmologist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient. If an examination indicates that corrective lenses are appropriate, the prescriber provides the patient with an eyewear prescription at the conclusion of the exam; the parameters specified on spectacle prescriptions vary, but include the patient's name, power of the lenses, any prism to be included, the pupillary distance, expiration date, the prescriber's signature. The prescription is determined during a refraction, using a phoropter and asking the patient which of two lenses is better, or by automated refractor, or through the technique of retinoscopy. A dispensing optician will take a prescription written by an optometrist or ophthalmologist and order and/or assemble the frames and lenses to be dispensed and sold to the patient.

Every corrective lens prescription includes a spherical correction in diopters. Convergent powers are positive and condense light to correct for farsightedness/long-sightedness or allow the patient to read more comfortably. Divergent powers are negative and spread out light to correct for nearsightedness/short-sightedness. If neither convergence nor divergence is required in the prescription, "plano" is used to denote a refractive power of zero; the term "sphere" comes from the geometry of lenses. Lenses derive their power from curved surfaces. A spherical lens has the same curvature in every direction perpendicular to the optical axis. Spherical lenses are adequate correction. To correct for astigmatism, the "cylinder" and "axis" components specify how a particular lens is different from a lens composed of purely spherical surfaces. Patients with astigmatism need a cylindrical lens, or more a toric lens to see clearly; the geometry of a toric lens focuses light differently in different meridians.

A meridian, in this case, is a plane, perpendicular to the optical axis. For example, a toric lens, when rotated could focus an object to the image of a horizontal line at one focal distance while focusing a vertical line to a separate focal distance; the power of a toric lens can be specified by describing how the cylinder differs from the spherical power. Power evenly transitions between the two powers as you move from the meridian with the most convergence to the meridian with the least convergence. For regular toric lenses, these powers are perpendicular to each other and their location relative to vertical and horizontal are specified by the axis component. There are two different conventions for indicating the amount of cylinder: "plus cylinder notation" and "minus cylinder notation". In the former, the cylinder power is a number of diopters more convergent than the sphere power; that means the spherical power describes the most divergent meridian and the cylindrical component describes the most convergent.

In the minus cylinder notation, the cylinder power is a number of diopters more divergent than the sphere component. In this convention, the sphere power describes the most convergent meridian and the cylinder component describes the most divergent. Europe follows the plus cylinder convention while in the US the minus cylinder notation is used by optometrists and the plus cylinder notation is used by ophthalmologists. Minus cylinder notation is more common in Asia, although either style may be encountered there. There is no difference in these forms of notation and it is easy to convert between them: Add the sphere and cylinder numbers together to produce the converted sphere Invert the sign of cylinder value Add 90° to axis value, if the new axis value exceeds 180°, subtract 180° from the resultFor example, a lens with a vertical power of -3.75 and a horizontal power of -2.25 could be specified as either -2.25 -1.50 x 180 or -3.75 +1.50 x 090. The axis defines the location of the cylinder powers.

The name "axis" comes from the concept of generating a cylinder by rotating a line around an axis. The curve of that cylinder is 90° from that axis of rotation; when dealing with toric lenses, the axis defines the orientation of the steepest and flattest curvatures relative to horizontal and vertical. The "3 o'clock" position is defined as zero, the 90th meridian is a vertical line. A horizontal line passes through both zero and the 180th meridians. By convention, a horizontal axis is recorded as 180. In a regular toric lens, the flattest and steepest curvatures are separated by 90°; as a result, the axis of the cylinder is the meridian with the same power as the recorded sphere power. The cylinder power, as defined above is the power, most different from the sphere power; because they are defined relative to each other, it is important to know if the lens is being described in minus cylinder notation, where the sphere power is the most convergent / least divergent power. When using plus cylinder notation, the opposite is true.

If the lens is spherical there is no need for an axis. A prescription like this is written with D. S. after the sphere power. This verifies that the prescription is spherical rather than the cylinder power being omitted in error. Correction power is measured in diopters by convention, an axis of 90° is vertical, 0° or 180° are horizontal if the cylinder power is positive, the lens is most convergent 90° from the axis if the cylinder power is negative, the lens is most divergent 90° from t