Contact lenses articles

Beta Flight is a fictional superhero team, owned by Marvel Comics that exists in that company’s Marvel Universe.

Along with Gamma Flight, Beta Flight is one of the “minor leagues” of the Canadian team, Alpha Flight, operated by Department H. Members have included Puck, Madison Jeffries, Wild Child, Windshear, Flex, Marrina, Radius, Feedback, Flashback and Nemesis. Beta Flight is the intermediate level team. Members are more experienced than the raw recruits of Gamma Flight but not yet ready to join Alpha Flight.

Eventually if a member from Beta Flight proves himself worthy they will get promoted to Alpha Flight.

External links

• AlphaFlight.net

Knapp’s Rule states that lenses placed at the anterior focal point of the eye, generally 15 mm in front of the eye, will create similarly sized images on the retina, whenever the disparity between the two eyes is due to a difference in axial length of the eyes.

When a refractive error is corrected with spectacle lenses, the retinal images change size. It is magnified with convex lenses and minified with concave lenses. One difficulty, then, in prescribing glasses to an individual with a disparity in refractive error between the two eyes is that a disparity in image size between the two eyes may be created.

There is some controversy as to the soundness of Knapp’s Rule.

In electrical engineering in the field of power transmission a per-unit system is the expression of system quantities as fractions of a defined base unit quantity. Calculations are simplified because quantities expressed as per-unit are the same regardless of the voltage level. Similar types of apparatus will have impedances, voltage drops and losses that are the same when expressed as a per-unit fraction of the equipment rating, even if the unit size varies widely. Conversion of per-unit quantities to volts, ohms, or amperes requires a knowledge of the base that the per-unit quantities were referenced to.

A per-unit system provides units for power, voltage, current, impedance, and admittance. Only two of these are independent, usually power and voltage. All quantities are specified as multiples of selected base values. For example, the base power might be the rated power of a transformer, or perhaps an arbitrarily selected power which makes power quantities in the system more convenient. The base voltage might be the nominal voltage of a bus. Different types of quantities are labeled with the same symbol (pu); it should be clear from context whether the quantity is a voltage, current, etc.

Per-unit is used primarily in power flow studies; however, because parameters of transformers and machines (electric motors and electrical generators) are often specified in terms of per-unit, it is important for all power engineers to be familiar with the concept.

Purpose

There are several reasons for using a per-unit system:

• Similar apparatus (generators, transformers, lines) will have similar per-unit impedances and losses expressed on their own rating, regardless of their absolute size.
• Use of the constant <math> \sqrt{3} </math> is reduced in three-phase calculations.
• Per-unit quantities are the same on either side of a transformer, independent of voltage level
• By normalizing quantities to a common base, both hand and automatic calculations are simplified.

The per unit system was developed to make manual analysis of power systems easier. Although power system analysis is now done by computer, results are often expressed as per-unit values on a convenient system-wide base.

Relationship between units

The relationship between units in a per-unit system depends on whether the system is single phase or three phase.

Single phase

Assuming that the independent base values are power and voltage, we have:

<math>P_{base} = 1 pu</math>

<math>V_{base} = 1 pu</math>

Alternatively, the base value for power may be given in terms of reactive or apparent power, in which case we have, respectively,

<math>Q_{base} = 1 pu</math>

or

<math>S_{base} = 1 pu</math>

The rest of the units can be derived from power and voltage using the equations <math>S = IV</math>, <math>P = Scos(phi)</math>, <math>Q = Psin(phi)</math> and <math> \underline{V} = \underline{I} \underline{Z}</math> (Ohm’s law), <math>Z</math> being represented by <math> \underline{Z} = R + jX = Zcos(phi) + jZsin(phi)</math>. We have:

<math>I_{base} = \frac{S_{base}}{V_{base}} = 1 pu</math>

<math>Z_{base} = \frac{V_{base}}{I_{base}} = \frac{V_{base}^{2}}{I_{base}V_{base}} = \frac{V_{base}^{2}}{S_{base}} = 1 pu</math>

<math>Y_{base} = \frac{1}{Z_{base}} = 1 pu</math>

Three phase

Power and voltage are specified in the same way as single phase systems. However, due to differences in what these terms usually represent in three phase systems, the relationships for the derived units are different. Specifically, power is given as total (not per-phase) power, and voltage is line to line voltage.
In three phase systems the equations <math>P = Scos(phi)</math> and <math>Q = Ssin(phi)</math> also hold. The apparent power S now equals <math>S_{base}= \sqrt{3}V_{base} I_{base}</math>

<math>I_{base} = \frac{S_{base}}{V_{base} \times \sqrt{3}} = 1 pu</math>

<math>Z_{base} = \frac{V_{base}}{I_{base} \times \sqrt{3}} = \frac{V_{base}^2}{S_{base}} = 1 pu</math>

<math>Y_{base} = \frac{1}{Z_{base}} = 1 pu</math>

Example of per-unit

As an example of how per-unit is used, consider a three phase power transmission system that deals with powers on the order of 500 MW and uses a nominal voltage of 138 kV for transmission. We arbitrarily select <math>S_{base} = 500 MVA</math>, and use the nominal voltage 138 kV as the base voltage <math>V_{base}</math>. We then have:

<math>Z_{base} = \frac{V_{base}^{2}}{S_{base}} = 38.1 \Omega</math>

<math>I_{base} = \frac{S_{base}}{V_{base} \times \sqrt{3}} = 2.09 kA</math>

<math>Z_{base} = \frac{V_{base}}{I_{base} \times \sqrt{3}} = 38.1 \Omega</math>

<math>Y_{base} = \frac{1}{Z_{base}} = 26.3 mS</math>

If, for example, the actual voltage at one of the buses is measured to be 136 kV, we have:

<math>V_{pu} = \frac{V}{V_{base}} = \frac{136 kV}{138 kV} = 0.9855 pu</math>

References

• William D. Stevenson, Jr. Elements of Power System Analysis Third Edition,McGraw-Hill, New York (1975) ISBN 0-07-061285-4

• B. M. Weedy, Electric Power Systems Second Edition, John Wiley and Sons, London, 1972, ISBN 0-471-92445-8

A follow focus is a piece of equipment that attaches to the focus ring of a manual lens via a set of rods on the body of a film or video camera. It is ergonomic rather than strictly necessary; in other words it does not contribute to the basic functionality of a camera but instead allows the operator to be more efficient and precise. It is usually operated by a focus puller (often called the 1st assistant camera, or 1AC) but some camera operators prefer to pull their own focus (the act of changing focus is called “pulling” or “racking” focus).

A manual lens is usually a requisite for professional filmmaking. This is because autofocus lens systems use lasers or infrared beams to measure the distance between the lens and the subject. This technique does not anticipate an actor stepping into the foreground of the frame, nor can it focus on anything which is not in the center of the frame. The job of the focus puller then is to adjust the focus onto different subjects as well as change, or (follow) focus during movement of the camera onto the required subject, hence the term.

The mechanism works through a set of gears on the follow focus that are attached to teeth on the focus ring of the lens. These gears feed to a wheel which when turned by a focus puller who will spin the teeth and thus the ring on the lens. Practically, the device is not necessary as the operator can directly turn the ring on the lens. However, this would place the hand in an awkward position perpendicular to the camera rather than parallel, and turning beyond a certain distance (such as 360 degrees) would be impossible. Sometimes, such a “focus pull” would even be difficult with a follow focus, so an L-shaped metal rod can be attached in the provided square hole at the center of the wheel. Thus, the hand merely has to spin the rod, which turns the wheel. The stationary white disk surrounding the wheel is used by the focus puller to jot down marks, and take care of the focus according to the marks he/she took during rehearsals. A focus puller often uses a tape to correctly measure the distance from the lens to the subject, allowing for accurate marking of the disk.

A follow focus is usually a compulsory piece of equipment for professional filmmaking, although those with low/no budgets or cameras not equipped with detachable manual lenses will have to do with autofocus systems or turning a lens ring by hand. To make matters worse, most autofocus lenses with a focus ring (such as those on most consumer and prosumer camcorders) are not “true” manual focus lenses, meaning that turning the ring does not directly adjust the elements inside the lens but rather actuates the electronics inside the camera which predict how the focus should go depending on how fast or far the ring was turned. These lenses make precise and repeatable focus pulls difficult, and use of a follow focus impractical. They are sometimes called “servo” focus lenses or “focus by wire” cameras.

Curve-fitting compaction is data compaction accomplished by replacing data to be stored or transmitted with an analytical expression.

Examples of curve-fitting compaction consisting of discretization and then interpolation are:

1. Breaking of a continuous curve into a series of straight line segments and specifying the slope, intercept, and range for each segment
2. Using a mathematical expression, such as a polynomial or a trigonometric function, and a single point on the corresponding curve instead of storing or transmitting the entire graphic curve or a series of points on it.

The Contact (접속, Cheob-sok) is a 1997 Korean romantic film directed by Chang Yoon-Hyun. Starring Han Suk-gyu and Jeon Do-yeon, it was the second biggest-grossing Korean film of 1997, and was awarded the Grand Bell Award for best picture.

External links

• 1997 Korean films at Koreanfilms.org
  

“How Long’s A Tear Take To Dry?” is a single by British pop group The Beautiful South from their album “Quench”. It was written by Paul Heaton and Dave Rotheray. The lyrics, which take the form of a conversation between two reconciling lovers, are noted for a reference to the TARDIS from Doctor Who. According to the book Last Orders at the Liars Bar: the Official Story of the Beautiful South, “How Long’s A Tear Take To Dry?” was originally to be called “She Bangs the Buns” due to its chord structure reminiscent of Manchester’s The Stone Roses.

Single release

“How Long’s A Tear Take To Dry?” reached number 12 in the UK Singles Chart in March 1999. Although not released on vinyl, it was given a dual-CD release in the UK. B-sides included a remix of “How Long’s A Tear Take To Dry?” as well as acoustic versions of three other songs: “Perfect 10″, “Big Coin”, and “Rotterdam”. On March 18th, 1999, the band performed “How Long’s A Tear Take To Dry?” live on the BBC’s music programme, Top of the Pops.

Video

The video, available on The Beautiful South’s compilation DVD Munch, is a humorous account of The Beautiful South on a world tour. The band is portrayed by cartoon versions of themselves, in a style reminiscent of 1960s-era Hanna-Barbera cartoons, and Scooby-Doo in particular. In the commentary track on the Munch DVD, Paul Heaton explains that the video was actually produced by Hanna-Barbera.

References

• Pattenden, Mike - Last Orders at the Liars Bar: the Official Story of the Beautiful South ISBN 0-575-06739-X)

An accident at work is defined as an external, sudden, unexpected, unintended, and violent event, during the execution of work or arising out of it, which causes damage to the health of or loss of the life of the employee (the insured).

For qualification as an accident at work to apply, there must be a causal relationship (direct or indirect relationship of cause and effect) between the violent event and the work. Only if the accident is due to “wilful misrepresentation” on the part of the employer or the employer’s appointed representative is the employer under an obligation to compensate the victim. Under U.S. law, injured workers are often compensated according to the type of injury, rather than permitting them to sue the employer for the actual damages.

There is a significant proportion of work accidents occurring in the merchant marine.

See also: industrial injury, social security, workers’ compensation

ACUVUE was the first-ever brand of disposable contact lenses, first marketed in 1986. They are made by Vistakon, a subsidiary of Johnson & Johnson, headquartered in Jacksonville, Florida. All of Vistakon’s manufacturing facilities are located in the United States, with the exception of one plant located in Limerick, Republic of Ireland.

External links

• ACUVUE Contact Lenses - Official Website
• ACUVUE Contact Lens Summary and Comparison - Official Website
• Johnson & Johnson Vision Care, Inc. (About the Manufacturer)
• ACUVUE Contact Lenses (Information about all ACUVUE brand lenses)
• ACUVUE Bifocal Contact Lenses (Information about ACUVUE contact lenses)

The perimeter is the distance around a given two-dimensional object. The word perimeter is a Greek root meaning measure around, or literally “around measure”.

Practical uses

Perimeter and area play a great role in today’s world. Perimeter is used in calculating the border of an object such as a yard or flowerbed when a fence or other border is being installed around the edges. Area is used when all the area inside of a perimeter is being covered with something, such as a yard being covered with sod or fertilizer.

Formulas

Polygons

As a general rule, the perimeter of a polygon can always be calculated by adding all the length of the sides together.
So, the formula for triangles is <math>P=a+b+c</math>, where <math>a</math>, <math>b</math> and <math>c</math> stand for each side of it. For quadrilaterals the equation is <math>P=a+b+c+d</math>. For equilateral polygons, <math>P=na</math>, where n is the number of sides and a is the measure of the side.

Circles

For circles the equation is

<math>

 P = 2 \cdot \pi \cdot r

</math>
or

<math>

 P = d \cdot \pi

</math>

• <math>P</math> stands for the perimeter,
• <math>r</math> stands for the radius
• <math>\pi</math> is the mathematical constant pi (<math>\pi=3.14159265…</math>)
• <math>d</math> stands for the circle’s diameter (twice the radius of a circle)

(The dot means multiply or times)

In General

If r is considered to be the distance from the centre of a regular polygon to one of its vertices (or in the case of a circle, the radius), the following holds true:

<math>P = \frac{dA}{dr}</math>

• <math>P</math> stands for the perimeter,
• <math>r</math> stands for the radius
• <math>A</math> stands for the area

See also

• Isoperimetric Theorem
• Circumference
• Pythagorean Theorem
• Wetted perimeter

External links

Forward-center is a basketball position for players who play or have played both forward and center on a consistent basis. Typically, this means power forward and center, since these are usually the two biggest player positions on any basketball team, and therefore more often overlap.

Forward-center came into the basketball jargon as the game evolved and became more specialized in the 1960s. Other terms, such as point guard, small forward and power forward, have come to describe similar subcategories of players, even as center, forward and guard are the only actual positions on most basketball teams.

Typically, a forward-center is a talented forward who also came to play minutes at center on teams that needed help at that position. Or the player could be a somewhat floor-bound center, under seven-feet tall at the NBA level, whose skills also suit him to a power forward position, especially if that team does have a better center. One such player is Marcus Camby of the Denver Nuggets. At 6-11 he generally plays center for the Nuggets but when he played for the New York Knicks earlier in his career he mostly played power forward due to his team having one of the better pure centers in the league in Patrick Ewing.

Center and forward typically have different skills sets. Common to both of them are scoring, passing and rebounding. A power forward who is a forward-center is also usually a strong inside defender, something a center also is usually expected to be.

Since a forward-center is not usually seven-feet or taller, perimeter shooting skills are usually needed to compensate for lack of height or size near the basket.

ACUVUE was the first-ever brand of disposable contact lenses, first marketed in 1986. They are made by Vistakon, a subsidiary of Johnson & Johnson, headquartered in Jacksonville, Florida. All of Vistakon’s manufacturing facilities are located in the United States, with the exception of one plant located in Limerick, Republic of Ireland.

External links

• ACUVUE Contact Lenses - Official Website
• ACUVUE Contact Lens Summary and Comparison - Official Website
• Johnson & Johnson Vision Care, Inc. (About the Manufacturer)
• ACUVUE Contact Lenses (Information about all ACUVUE brand lenses)
• ACUVUE Bifocal Contact Lenses (Information about ACUVUE contact lenses)

Kings Avenue is a station on the JTA Skyway. It is located on Onyx Street between Prudential Drive and Louisa Street, and is the southern terminus of the system. A nearby parking garage operated by the Jacksonville Transportation Authority can be reached by a walkway under Interstate 95.

The next station in the line is Riverplace.

La Traversée de l’Atlantique (Atlantic Crossing) is a 1986 album by La Bottine Souriante.

Track listing

1. “Sur le pont d’Avignon”, – 3:18
2. “Le meunier et la jeune fille”, – 3:15
3. “Le reel des vieux/Le reel à Jules Verret”, – 2:57
4. “J’aurai le vin/Le reel du petit cheval de bois”, – 4:38
5. “La belle ennuitée”, – 2:00
6. “La traversée de l’Atlantique/Le set carré à Pitou Boudreault”, – 2:49
7. “Le lac à Beauce / Le reel St-Jean”, – 3:45
8. “La Madelon”, – 2:33
9. “Le reel du mal de dos/Le reel à Jean-Marie Verret”, – 2:34
10. “La Chanson des menteries”, – 4:18
11. “Hommage à Philippe Bruneau / La Valse d’hiver”, – 4:18
12. “La chanson des pompiers”, – 2:12

In geometry, the bigyrate diminished rhombicosidodecahedron is one of the Johnson solids (J₇₉).

The 92 Johnson solids were named and described by Norman Johnson in 1966.

External links

For information on the number 1000, see 1000 (number).

I Feel It/Thousand is the name of a single released by techno artist Moby. “Thousand” has the Guinness world record for the fastest tempo in beats-per-minute (BPM) of any released single, although some Speedcore songs have surpassed it. It clocks in at approximately 1,000 BPM, hence the title of the recording.

A microkeratome is a precision surgical instrument with an oscillating blade designed for creating the corneal flap in LASIK or ALK surgery. The normal human cornea varies from around 500 to 600 micrometres in thickness; and in the lasik procedure, the microkeratome creates a 100 to 200 micrometre thick flap.

Single set back (also known as the “Lone Setback” or “Ace” formation or “Oneback” or “Solo”) is an offensive base formation in American Football which requires only one running back lined up about five yards behind the quarterback. There are many variations on single back formations including two tight ends and two wide receivers, one tight end/three wide receivers, etc. The running back can line up directly behind the quarterback or offset either the weak side (away from the tight end) or the strong side (towards the tight end).

This formation has gained popularity in the NFL as teams have started trading out a fullback, or blocking back, in favor of another wide receiver or tight end who is usually faster and better able to receive the ball, while still helping the run game with down-field blocks. The effectiveness of the formation is further increased if the team has athletic tight ends with good hands, thereby increasing the versatility of the formation. It is, moreover, good for bootlegs and reverses.

Single-back offenses have gained popularity due to zone blocking and advanced defenses. There are several combinations of single back formations that are used in Division 1 and NFL football. Speed offenses will use single back because the defense still has to respect the run out of these formations since you can line up many tight ends and still have a down field running game. Single back offenses create match-up problems in the defense. Linebackers will often have to cover receivers in passing routes while defensive safeties are used more to come up and stop the run on the line of scrimmage. Teams that run a single-back offense typically rely on quick receivers that run great routes, balanced tight ends (blocking/receiving), intelligent, shifty running backs, fast and intelligent offensive lineman, and a quarterback that can read defenses and make safe throws under pressure. Single-back offenses are more common in the NFL than in college or high school.

Laser surgery may refer to:

• The use of a laser scalpel in surgery
• Laser resurfacing, a technique in which molecular bonds of a material are dissolved by a laser
• LASIK, a form of refractive laser eye surgery procedure performed by ophthalmologists to correct near- and far-sightedness in vision
• Photorefractive keratectomy, a procedure which permanently reshapes the cornea using an excimer laser to remove a small amount of tissue

Welch Allyn, Inc. was founded in 1915 and is today a leading manufacturer of innovative medical diagnostic and therapeutic devices, cardiac defibrillators, patient monitoring systems, and miniature precision lamps. Headquartered in Skaneateles, New York, USA, Welch Allyn employs more than 2,300 people and has numerous manufacturing, sales, and distribution facilities located throughout the world.

External links

• Welch Allyn website