How A Crossbow Works An Educational Guide To Crossbows}

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Submitted by: Jen Walterscheit

The crossbow is a combination of an archery bow and a rifle. The standard archers bow it uses a string to launch ammunition. However, like a rifle, it has a trigger that releases the string.

Advantages of a Crossbow

The nice feature of the crossbow when compared to other bows is there is less physical strength needed to draw the bow as compared to a traditional bow. The crossbow user can draw the string, cock it, and leave the string while taking aim. More traditional bows require the archer to hold the bow at full draw while aiming. In addition, to draw a crossbow requires the use of the archers buttock and thigh muscles. These muscles are much stronger than the arm and chest muscles required of a standard bow user.

Crossbow Physics

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The crossbow of today is made of strong lightweight materials. The bow is simply a spring. If you compress a spring or pull a spring from either end it stores potential energy that is released as kinetic energy when the spring is released and returns to its normal shape.

The same thing happens to a crossbow. When you draw the bow, the limbs or tips move closer to the archer. When the string is let go the bow returns to its standard shape. The movement of the bow back to its original shape is what launches the projectile.

Energy Stored

The amount of energy in a bow depends on its draw weight and draw length. The draw weight is the strength needed to pull the bowstring back. The draw length is the distance between the string at rest and the string fully pulled back. A bow can hold energy equal to the draw weight times the draw length divided by two. In other words, the power of a bow depends on how much strength it takes to pull back the string of the bow and how far back you can pull it. Bow makers express this strength in terms of the bows energy measured in joules and the arrows speed in feet per second.

Factors that affect the draw weight and draw length

The size of the bow can change a bows power. A longbow is more powerful than a short bow. The shape of the bow affects speed of the projectile. For example, recurve bows have bows that curve away from the archer and this shortens the bracing height. As a result extra momentum is forced onto the projectile. The composition of the bow can also affect is power. A bows tensile strength and density determine not only the amount of energy it holds but also how quickly and exactly it can return to its original shape. Todays bows use different materials in different parts of the bow to better serve that particular part or function of the part.

As you can see the crossbow works like a spring. As the spring is compressed, or the bowstring drawn back energy get stored as potential energy. When the trigger of the crossbow is released, like the spring, the crossbow will return to its original resting state dispensing the potential energy it stored as kinetic energy. This kinetic energy is responsible for launching the ammunition at high velocity.

About the Author: At Eagle Archery we are dedicated to providing you with the largest selection of

Crossbows

on the Internet. We stock over 10,000 products, and are adding more all the time, including but not limited to a great selection of

Crossbows

.

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2,000 face redundancy at English steelworks

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Saturday, May 9, 2009

Corus Group, the world’s fifth largest steel producer, announced on Friday that it may be forced to mothball its steelworks in Redcar, England. This move would threaten the jobs of the works’ 1,920 employees.

Corus may be forced to close its Teesside operations as a consortium has refused to honour a 10-year contract with Corus’ Teesside Cast Products, which accounted for 78% of the plant’s operations. Corus’ chief executive, Kirby Adams, said he was “extremely disappointed that the consortium members have seen fit to take this irresponsible action.”

Lord Mandelson, Secretary of State for Business, Enterprise and Regulatory Reform, said “it is essential that Corus does everything it can legally, and with the government’s assistance, to reinstate the agreement”. Gordon Brown, the British Prime Minister, shared this view saying, “We are doing everything in our power to ensure that the contract is upheld.” Mandelson also said “we are not prepared to reconcile ourselves to the inevitable closure of this plant”.

The leader of Redcar & Cleveland Borough Council, Councillor George Dunning, said “Today is like being hit by a mini earthquake compared to what’s happened in the past.”

Martin Callanan and Stephen Hughes, Tory, and Labour MEPs for North East England, supported the idea that the government should subsidise wages in the plant on a temporary basis. Hughes and Fiona Hall, Lib Dem MEP, suggested that the government should apply to the EU’s Globalisation Adjustment Fund. Hall said “if the worst comes to the worst and jobs are indeed lost, I trust the Government will change its mind and support an application to the European Globalisation Fund in order to fund skills training for those who have lost their jobs.”

This move could “bring to an end a fine heritage of steelmaking at Teesside”, according to Adams. Steelworks in Teesside, which previously belonged to British Steel and Dorman Long, produced steel for famous structures like the Sydney Harbour Bridge.

Corus had said it was likely there would be a “very significant number of redundancies” and a 90-day consultation period is due to begin.

Corus’ owner, Tata Steel, are also facing difficulties with another UK operation, automobile company Jaguar Land Rover.

Wesley So wins TATA Steel Chess

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Wednesday, February 1, 2017

On Sunday, Filipino-US chess grandmaster Wesley So won this year’s Tata Steel Chess Tournament, held in Wijk aan Zee, Netherlands, securing 9.0 points out of thirteen. Following closely in second place was current World Champion Magnus Carlsen with 8.0 points.

Wesley So won five games and drew the remaining eight. A player gets a point for each win, half a point for a draw and no points for a loss. He is currently on a 56 lossless game streak.

In the final round, Wesley So was paired against Russian grandmaster Ian Nepomniachtchi. Wesley So captured a central pawn which was expected to be recaptured to equalise material but wasn’t. Soon, his opponent unexpectedly castled offering a pawn sacrifice which was accepted. Despite being ahead in material his opponent threatened to capture his queen. However, he was able to defend using his extra central pawn and prevent counter-play forcing the Russian to resign.

He won last year’s Grand Chess Tour by winning the Sinquefield Cup and London Chess Classic and coming second in the Leuven Grand Chess Tour.

Magnus Carlsen won four, tied eight and lost a game against Richárd Rapport. In the last round he faced his rival and contender for the World Chess Championship of the last year, Russian Sergey Karjakin. In the game, Karjakin provoked Carlsen to sacrifice his knight on which grandmaster Fabiano Caruana tweeted, “Karjakin must be in a very charitable mood”. He quickly sacrificed his knight pinning Karjakin’s knight to his queen. Despite being a piece down he gained an advantageous position. Karjakin defended his position extremely well, as grandmaster Alejandro Ramírez said, “He can commit the most despicable errors and then show world-class toughness from the next second!”. The defence worked and a draw was agreed upon.

Also known as the “Wimbledon of Chess”, the Tata Steel Chess tournament attracts top chess players every year. The tournament has two professional groups, Masters and Challengers, and an amateur group. It is organised in a round-robin format where each player plays a game against all other players. The tournament is scheduled to run its 80th edition next year in Wijk aan Zee, Netherlands.

Queensland prisoners put to work manufacturing water tanks

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Monday, April 30, 2007

Prisoners in the Australian state of Queensland have been put to work manufacturing rainwater tanks to help meet a shortfall in supply.

The southeast corner of Queensland, which is currently undergoing one of its worst droughts on record, is experiencing a boom in the rainwater tank industry. Households, encouraged by subsidies introduced by the Beattie government, have enthusiastically begun installing rainwater tanks as well as other water-saving devices. These subsidies have led to a shortfall in supply however, with some households waiting months for tanks to be installed.

The new initiative, announced by Premier Peter Beattie as well as Corrective Services minister Judy Spence will see prisoners at Woodford Correctional Centre, Australia’s largest gaol, constructing tanks for AU$4 per day. Spence has pledged not to use the cheap labour to undercut existing tank suppliers. Beattie also pointed out that the programme would give prisoners constructing the tanks valuable work skills for when their sentences are completed. If the programme is successful, it may be extended to other gaols around the state.

The Beattie government has been increasingly criticised over recent months for its failure to handle the water crisis engulfing Southeast Queensland. Opponents accuse the Government of a lack of planning foresight with regards to water supply for the booming area, which includes state capital Brisbane, as well as other cities such as Ipswich, Toowoomba and Gold Coast.

Botox For Migraine Headaches}

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Submitted by: Mary Betz

Botox for migraine headache is one of the newer advances to come along within the last five years. Many people are familiar with Botox and usually the first question providers get is..”can you get rid of my wrinkles too??” Well..yes and no. Wrinkles in forehead, yes, around the eyes, you have to see the plastic surgeon for that one!

Botox for migraine headache is a form of botulism toxin that is extremely diluted. The injections are given in small amounts, about one tenth of a milliliter, and placed just under the skin, near the nerves that cause pain.

It also causes paralysis of the muscles in the area and is sometimes used for neck spasms known as dystonias, torticollis or “wry neck”. Sometimes this is also a part of the problem with migraine, as chronic spasms in the neck will cause headaches.

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So where are the injections? The injections are placed across the forehead, and just between the eyebrows. They are always placed on both sides of the head, no matter on which side your headaches are frequent. After all, you would look pretty funny with lines on one side of your forehead and not the other, right? Injections are not placed past the midline of the eyebrow as that would paralyze the eyebrow (for a few months) and you would not be able to raise them. (There goes that look of surprise!) Additional injections are placed in the temporal muscles on both sides of the temple. If neck pain is a problem, then injections may be placed just under the skin in the neck.

Side effects of Botox injections include irritation at the injection site which may last a few days, and a minute amount of blood at the injection site. If given in the neck, weakness of neck muscles may be noticed but it is usually not severe. The success rate with Botox for migraine has been reported to be as high as 75%, but clinically many see about a 50% success rate.

Injections are given every 2-4 months depending on the patient and how soon the first set begins to wear off. Many insurance companies are beginning to pay for Botox for migraine and even for chronic daily headache, so check with yours to see if you qualify. If you don’t, the cost per session is about one thousand dollars and perhaps more depending on where you live.

So how do you know if you are a candidate for Botox for your headaches? Well you have to have severe headaches that have not responded well to other medications. Also, chronic daily headache or two or three disabling migraines per month would also be a good reason to consider Botox.

Botox does not cure headaches! Like many other medications for headache, Botox offers another medium for headache management. If successful, Botox allows may allow you to reduce, and perhaps eliminate, your other headache medications. Once you are stable, say one or two headaches per month, the Botox can be discontinued.

Talk to your provider, ask for a referral to a headache center to find out more about Botox for migraine.

About the Author: Mary K. Betz, MS RPA-C is a practicing Physician Assistant who specializes in headache medicine. For more information visit

Botox for migraine headaches at Headache-adviser.com

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Entrepreneur’s RFID chip implant to open doors, start car

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Thursday, March 24, 2005

A technology entrepreneur in northeastern Washington asked a doctor to implant an RFID chip into his hand in order to experiment with the technology. Amal Graafstra, who runs a technology company in Bellingham, WA, asked a doctor to place the chip under the skin of his left hand, and posted pictures of the procedure to the photo-sharing site, Flickr. Graafstra plans to use the chip for keyless entry to his car, home, or as a login for computer systems.

Implanting RFID chips is a relatively old technology. Professor Kevin Warwick of the University of Reading, UK implanted a 23mm RFID chip into his left arm in August 1998. It allowed him to open doors and turn on the lights in a room as he entered. Further European research in the area was recently dealt a blow when the European Group on Ethics in Science and New Technologies made a presentation to the European Union raising privacy concerns over the potential for such chips to be used to track members of the public.

In mid-2004, about 160 Mexican officials received RFID implants for security purposes, and scientists in the past have implanted themselves with such chips for research purposes. In October 2004, the U.S. Food and Drug Administration (FDA) approved the implantation of Verichip technology for medical purposes.

An implantable RFID chip is a minuscule capsule containing a microchip and an antenna, all enclosed in glass. The chip that Mr. Graafstra had implanted was 12mm long and 2mm in diameter — about the size of a grain of rice. RFID chips work by storing a unique identification number in the microchip. This number can be retrieved by a special RFID reader that is held within close proximity. Graafstra notes that his chip can be read from a distance of about 2 inches (5cm), and only provides the single identifying number.

Describing himself as a long-time tinkerer, Graafstra’s comments do not show much of a hesitation to perform this process. “I like to mod things, and I guess it was only natural that it extended to my own body,” he wrote in an email to Wikinews.

Graafstra appears to have been impressed by the process, too. “It was odd feeling it [the chip] being pushed under the surface of my skin… without feeling pain, I was able to really get a feel for just how utilitarian our bodies actually are and how… separate the skin layer really is from the muscle layer under it,” he told Wikinews. He was able to use his hand to perform technical computer maintenance just an hour after the procedure.

RFID is a controversial technology. Privacy advocates fear that the technology might be abused by governments and used to track people. Microchip implants have been used for years for tracking lost pets.

The pictures that Graafstra posted spurred commentary in the blogosphere, with some assuming that the pictures — or the process — were faked. Graafstra denies this, and posted a short video of himself triggering the RFID reader with a swipe of his hand.

Interview with Reggie Bibbs on his life with neurofibromatosis

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Friday, December 14, 2007

Neurofibromatosis (NF) is a genetic condition causing benign tumors (neurofibromas) to grow along certain types of nerves and, in addition, it can affect the development of bones or skin. There are several variants of the disease but type 1 and type 2 NF account for the vast majority of cases.

The disease manifestations can vary from very mild to severe. Major symptoms include growths on and under the skin; skin pigmentations called café au lait spots in type 1; acoustic nerve tumors and consequent hearing loss in type 2. Growths can affect nearly all parts of the body, and pressure on nearby structures can cause a wide variety of complications. There is a small risk that the tumors transform into malignant cancerous lesions.

NF is one of the most common single-gene human diseases; around 1 in 2,500-4,000 live births are affected by NF-1, whereas NF-2 occurs in about 1 in 50,000-120,000. Both type 1 and 2 are autosomal dominant conditions, meaning that only one copy of the mutated gene need be inherited to pass the disorder. A child of a parent with neurofibromatosis and an unaffected parent will have a 50% chance of inheriting the disorder. The gene responsible for NF-1 and possibly NF-2 is thought to function as a tumor suppressor gene.

In most cases of neurofibromatosis 1, patients can live normal and productive lives. In about 25-40% of patients there is an associated learning disability with or without ADHD. In some cases of neurofibromatosis 2, the damage to nearby vital structures, such as the cranial nerves and the brainstem, can be life-threatening. When tumors are causing pain or disfiguration, surgery is thus far the only proven beneficial treatment option.

Reggie Bibbs is a 43-year-old-man living in Houston, Texas. Mr Bibbs was born with a genetic disease called neurofibromatosis (NF), which causes him to develop tumors on his body (see infobox on the right). NF can be a subtle disease, but in Bibbs’ case it has left him with a disfigured face and deformed leg. But he is happy with the way he looks, and doesn’t want to change his appearance to please other people. He has launched a successful campaign entitled “Just Ask”, and that’s just what Wikinews did in a video-interview.

The interview was prepared by Wikinews reporter Michaël Laurent with the help of Bertalan Meskó (who has a popular genetics and web 2.0 blog). Their questions were sent to a close friend of Mr. Bibbs, Lou Congelio, who kindly conducted the interview.

Contents

  • 1 Infobox: What is neurofibromatosis?
  • 2 The interview
    • 2.1 On neurofibromatosis
    • 2.2 Growing up
    • 2.3 A head to toe body tour
    • 2.4 The daily life of Reggie Bibbs
    • 2.5 Raising awareness and his campaign
  • 3 Sources
  • 4 External links
This exclusive interview features first-hand journalism by a Wikinews reporter. See the collaboration page for more details.

The Benefits Of Custom Commercial Kitchens

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The Benefits Of Custom Commercial Kitchens

by

Malcolm M Cox

The difference between commercial and domestic kitchens is stark. While kitchens in the home are only designed for small scale cooking, commercial kitchens in restaurants and catering facilities must accommodate an entire team of chefs and serve hundreds of meals daily. Not only are commercial kitchens busy, they also must meet stringent regulations for safety and cleanliness. Due to the unique requirements of commercial kitchens, it is not possible to repurpose materials and kits designed for domestic use. Instead, businesses in the hospitality industry almost always require customs built kitchens.

The great thing about customised commercial kitchens, is that they are superior in almost every way to their domestic counterparts. Below are just a few of the compelling reasons to have a custom kitchen designed for your business.

Durable

Being a fast paced working environment, it is crucial that commercial kitchens are built with durability in mind. Because of this, designers of custom commercial kitchens avoid using wooden or laminated bench tops which are commonly found in domestic kitchens. These materials are poorly suited to the rigours of a commercial kitchen, as they are far more easily damaged than bench tops made from harder materials, such as stainless steel.

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Even with durable materials, it is also imperative that commercial kitchens are well constructed. Poor workmanship can result in easily damaged benches and preparation surfaces. It can be a disaster to have the kitchen damaged during a peak period, so you need to ensure that you only employ the best contractors to construct your commercial kitchen.

Quality Fittings

While it is important to have quality bench tops and food preparation surfaces, it is also crucial that top quality fittings are used when designing and constructing a commercial kitchen. Any cooktops, ovens, range hoods and even taps need to be able to stand up to a real beating! Chefs and kitchen staff are not known for being gentle with equipment in the kitchen they are much more focussed on working quickly and efficiently! You need to ensure that all the fittings in the kitchen are ergonomic and durable. Products for the domestic market rarely measure up, so you need to ensure you only use quality fittings designed for commercial kitchens.

Custom Designed

They key benefit of a custom kitchen should be obvious it can be modified to exactly suit your requirements and the constraints of your building. If you are not accustomed to working in kitchens yourself, you should either consult an experienced chef or follow the advice of the contractor you have hired to design the kitchen. Commercial kitchens have a very specific layout and if you get it wrong, it can severely hamper the ability to serve food quickly and efficiently.

Stainless Steel Construction

As mentioned above, most commercial kitchens use stainless steel in their construction. As well as being durable, stainless steel provides a very sanitary surface for food preparation. Stainless steel has properties which make it resistant to the growth of bacteria and it is easily kept clean. In many jurisdictions, stainless steel food preparation surfaces are a mandated food safety requirement.

For more information, or to have someone design a kitchen that perfectly suits the need of your business, you should contact a specialist contractor in your area.

If you are searching for quality sheet metal products for the WA hospitality industry then

CoolSteel

is the right place to be. They custom fabricate commercial fridges, food & beverage display cabinets, stainless steel benches, bench tops and more. Click on this website

coolsteelfabrication.com.au

for additional details.

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ArticleRich.com

Los Angeles undergoing large power outage

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Monday, September 12, 2005

A power outage in a large portion of Los Angeles, California occurred at approximately 13:00 PST (20:00 UTC) on Monday. Reports from the Los Angeles Department of Water and Power indicate that the incident was caused by a worker who accidentally cut a line. The outage caused a chain reaction that took out power to a large part of the city.

According to local television stations, power is being returned to some of the city, including the UCLA Medical Center. Police are on “full tactical alert”, meaning that they will only respond to serious calls and all officers must remain on duty. Most officers are directing traffic.

Los Angeles International Airport briefly was affected but generators engaged shortly thereafter. No flights were delayed or cancelled.

According to the Department of Water and Power, the shutdown happened because of a mechanical problem at two receiving stations. The system automatically triggered a shutdown when a line was cut. DWP spokesman Ron Deaton said that if there is an increase in the power stations automatically shut down. “You cut the wrong wire and it triggers the system to shut down. We have finished repairing the transmission systems. Some units are not up yet, but we have other generating parts of the system. All that remains is the distribution of the power to the individual customers.”

The DWP is currently restoring power by redirecting it from other areas.

The DWP, LAPD, the DOD and Department of Homeland security immediately assured the public that the power outage has nothing to do with terrorism or sabotage, and that the identity of the worker(s) who cut the power lines will not be released.

Category:June 8, 2010

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