What are Lasers Used for

Lasers are used in practically every major industry, from medicine and computers, to entertainment and construction. A power rating, usually in watts, determines the strength of the laser. Some lasers can cut through metal, while others merely read tiny bits of information without damaging the surface. Basically, the application of lasers can be divided into marking, etching, and cutting, or reading and scanning.

In the medical industry, carbon dioxide lasers are used in many types of surgery because they are more precise and sensitive than scalpels. Lasers remove tattoos without needing skin grafts, as well as painlessly clearing rot out of teeth. These less invasive lasers result in faster recuperation from surgeries such as removing certain tumors and correcting vision by reforming the eyeball lens. Damage to surrounding tissue, as well as bleeding, has been reduced by incorporating lasers.

Many common home or office devices house lasers as an intrinsic part of their performance. CD, DVD and Blu-Ray players use lasers to read the audio and video information on the disc, the way a needle used to read the groove of a record. CD, DVD and Blu-Ray recorders have stronger lasers that can burn the information onto the surface of the disc, either temporarily or permanently. Laser printers also utilize lasers to change a surface, in this case paper, to display text and graphics. Even at the grocery store, lasers scan the barcode on your packages to tell the computerized register what you're buying and how much it costs.

Lasers of the appropriate strength can etch surfaces from plastic to rock. Some companies inscribe a minute identification number on diamonds to keep track of them. Tombstones made of granite or limestone are carved with powerful lasers. Numerous metal pieces can be precisely cut out, drilled, and welded together to make a finished product using lasers capable of melting metal.

Even though the first laser was made in a laboratory back in 1960, it took several decades to apply this tool to various technologies. Now, lasers are indispensable to our daily lives. Visible lasers have even replaced strings, levels, and stakes in surveying equipment. Everyone should be treated to a laser show inside a planetarium, where colored lasers of all widths simulate the night sky.

What Is an Elmo™ Projector

An Elmo™ projector is a document camera and projection system that is commonly used as a descriptive name for all such systems, regardless of who manufactures them. This is not a correct use of the term and many companies fear when a situation like this develops that they could actually lose the value of their name. In most cases, if the brand is unknown, using the term document camera or document projector instead of Elmo™ projector is advisable.

The main purpose of an Elmo™ projector is to display documents and other objects that are not translucent -- in other words, documents that are not made with transparencies. These documents require a video camera and projection lens in order to work properly. The Elmo™ camera is usually digital. However, they are able to display more than just documents. In many cases, they can be used to display three-dimensional objects as well, though they will be rendered in two dimensions on the screen.

The thought behind the Elmo&trade projector is similar to that of the overhead projector, which came into widespread use during the late 1950s and continued through the 1990s. Such projectors were useful in making materials available to a wide audience in a classroom or group setting, but could only display documents put on transparent material. While duplication to transparencies is easily done, it required an additional step. Further, three-dimensional objects could not be displayed. They would instead be rendered as a black shadow in the area where they were blocking light from passing through.

The document projector changes all of those limitations. In fact, it is not only possible to display documents and objects on an Elmo™ projector, it is possible to even display moving pictures, such as movies. However, this is, by no means the most effective way of displaying such media. The camera used for a document projector does not operate with as many frames per second as standard video cameras. Thus, any movement would appear jumpy. That is one reason they are often called Elmo™ document cameras. It is understood that motion is not important in displaying documents.

Likewise, when looking at three-dimensional objects with Elmo™ document cameras, they should be kept still, or moved very slowly. Often, this is not a problem. If another side of the object needs displayed, it can simply be moved to face the camera. In such cases, the motion is not important and is only used to facilitate the change in the point of view.

Is it Possible to Send a Text Message to a Landline Telephone

As counterintuitive as it may sound, it is possible for certain cellular phone customers to send a text message to a landline. The recipient of such a text message does not need a modified telephone, however. The text message is automatically converted to an automated voice message through "text to voice" technology. All the recipient must do is listen to the message and respond with a recorded voice message of his or her own.

When a cellular phone customer sends a text message to a landline, he or she must first compose the message using a Short Message Service (SMS) format and then input the ten digit phone number of the recipient's landline phone. The cellular phone service provider will attempt to send the text message to a landline at least three times. If the recipient answers the phone, he or she should hear the automated voice message. If the landline phone is not answered, the message may go to voice mail or an answering machine.

Depending on the cellular provider, customers who have subscribed to the SMS service can send a text message to a landline anywhere in the United States, its territories, and possibly Canada. The text to voice program does not require the recipient to install any special equipment or subscribe to a cellular phone service. The sender usually receives a confirmation message stating that the text message has been successfully delivered to the landline.

While it is possible to send a text message to a landline, it is not generally possible to send a text message from a landline to a cellular phone. The recipient of a text message can sometimes choose from a menu of possible responses and send a voice message, but this voice message will not be converted to text on the cellular phone side.

Standard texting and phone call rates apply when sending a text message to a landline phone, and the phone number must be a recognized landline, not another cellular phone.

What Is Airplane Mode on a Cell Phone

Airplane mode is a setting on many cellphones which disables their wireless communication abilities, theoretically making them approved for use on aircraft. While in airplane mode, a phone cannot send or receive phone calls, text messages, picture messages, or video messages, and the user may not browse the Internet on the phone or use Bluetooth® devices with it. However, functions like music players, games, calendars, and so forth can continue to be used.

The idea behind airplane mode is that many people wish to continue using their cell phones on planes to do things like listen to music and check appointments, but the use of cell phones on planes is banned due to the fact that their signals could cause interference. Airplane mode allows cell phone users to circumvent the ban, ensuring that their phones are safe to use on aircraft while the plane is in flight; electronic devices must be turned off for takeoff and landing.

There are two reasons why people are not allowed to use cell phones on aircraft, although the rules against cell phone usage may change at some point. The first reason is that the radio signals emitted by phones could interfere with the communications and guidance systems on the aircraft, which could potentially be very dangerous. In addition, cell phone networks on the ground cannot cope with cell phones being used on planes, because planes travel very fast and at high altitude, so a phone on a plane could confuse a network on the ground.

If a phone offers an airplane mode setting, the user's manual usually clearly shows how to turn airplane mode off and on, and typically it can also be found through the phone's menu. When airplane mode is activated, a small icon often shows up on the screen of the phone to indicate this. In some cases, the user may have to use a password to activate and turn off airplane mode, to ensure that it is not accidentally switched on and off.

Although airplane mode technically makes a phone legal to use on an aircraft, some airlines request that passengers turn their cellphones off anyway, or a flight attendant who is not familiar with the technology may ask you to turn your phone off. Sometimes, explaining that you are using airplane mode is sufficient, and the flight attendant will allow you to leave your phone on, but in other cases, you may be asked to turn it off. Although this may seem unreasonable, it is better to comply; in the wake of the 11 September 2001 terrorist attacks in the United States, airlines are entitled to remove passengers from flights if they fail to comply with requests the airline terms “reasonable.”

What is HSDPA

HSDPA, short for High-Speed Downlink Packet Access, is a new protocol for mobile telephone data transmission. It is known as a 3.5G (G stands for generation) technology. Essentially, the standard will provide download speeds on a mobile phone equivalent to an ADSL (Asymmetric Digital Subscriber Line) line in a home, removing any limitations placed on the use of your phone by a slow connection. It is an evolution and improvement on W-CDMA, or Wideband Code Division Multiple Access, a 3G protocol. 

HSDPA improves the data transfer rate by a factor of at least five over W-CDMA. HSDPA can achieve theoretical data transmission speeds of 8-10 Mbps (megabits per second). Though any data can be transmitted, applications with high data demands such as video and streaming music are the focus of HSDPA.

HSDPA improves on W-CDMA by using different techniques for modulation and coding. It creates a new channel within W-CDMA called HS-DSCH, or high-speed downlink shared channel. That channel performs differently than other channels and allows for faster downlink speeds. It is important to note that the channel is only used for downlink. That means that data is sent from the source to the phone. It isn't possible to send data from the phone to a source using HSDPA. The channel is shared between all users which lets the radio signals to be used most effectively for the fastest downloads.

The widespread availability of HSDPA may take a while to be realized, or it may never be achieved. Most countries did not have a widespread 3G network in place as of the end of 2005. Many mobile telecommunications providers are working quickly to deploy 3G networks which can be upgraded to 3.5G when the market demand exists. Other providers tested HSDPA through 2005 and are rolling out the service in mid to late 2006. Early deployments of the service will be at speeds much lower than the theoretically possible rates. Early service will be at 1.8 Mbps, with upgrades to 3.6Mbps as devices are made available that can handle that increased speed.

The long-term acceptance and success of HSDPA is unclear, because it is not the only alternative for high speed data transmission. Standards like CDMA2000 1xEV-DO and WiMax are other potential high speed standards. Since HSDPA is an extension of W-CDMA, it is unlikely to succeed in locations where W-CDMA has not been deployed. Therefore, the eventual success of HSDPA as a 3.5G standard will first depend upon the success of W-CDMA as a 3G standard.

What Is a DECT Phone

Digital Enhanced Cordless Telecommunications (DECT) phones are devices that can be used to communicate through phone lines without a cord connecting the handset and base. The analog technology used in earlier cordless phone models could result in sound quality that was not always very good. With digital technology, the sound is clearer, the distance between the phone and the base station can be greater, and a wider range of frequencies are available.

Properties and Features

A DECT phone, commonly known as DECT 6.0 in the US, requires a base station to charge the handset and receive the phone's signal. It usually comes with one handset, but additional ones can be added on some models. This makes them useful in homes with multiple floors or large layouts, and for offices that want several cubicles to access the same phone system. Each handset is set up to communicate with the same base station, and usually comes with its own charging dock or "cradle."

The range of use for a handset depends on the phone itself, though it typically can reach over 300 feet (up to 100 meters). Digital technology allows a DECT phone to have much greater range than was previously possible, though this can be affected by various environment factors. Objects between the handset and base, for example, can potentially disrupt the signal and reduce the range of these phones. 

Some DECT phones can be used with general wireless technology, allowing different handsets connected to the same base station to be used as walkie talkies. Other standards, such as Wi-Fi®, have been more popular in some markets, however, so DECT technology has not expanded to many other devices in places like the US. A DECT phone can often be used with Voiceover Internet Protocol (VoIP) technology, allowing it to remain functional with the new communication platform.

Risks and Concerns

One of the biggest issues with DECT 6.0 technology in the US is that it does not include a single technology profile for use by all manufacturers. This means that a handset produced by one company does not typically function with a base or accessory made by another. Someone using a DECT 6.0 phone should look for accessories and parts made by the same manufacturer to ensure all of the components are compatible.

There is some question of how secure the signal is from this type of phone. DECT technology uses encryption to protect the signal, but the encryption has been broken and someone could potentially listen in on a phone call. It is also possible for someone to intercept the signal from a handset to the base. This allows a different device to act as the base, sending a call through it to another location, rather than through the actual base and phone line.

There is concern among some people about the radiation released by DECT phones. In general, they emit only a low level of radiation during use and while charging; even using the phone frequently should not cause any health issues. Many devices used on a daily basis do emit some radiation, however, and while individually these items are harmless, there is some concern about the possibility that long-term use of multiple devices could result in sufficient cumulative exposure for health concerns. Research into this exposure is ongoing.

History and Terminology

The DECT phone was initially introduced in Europe, and was first referred to as a "Digital European Cordless Telephone." It has since become an industry standard in many parts of the world. The term "DECT" by itself is typically used in Europe and other regions, such as Australia and different Asian countries. 

In the US, the term "DECT 6.0" is used, but this does not indicate any particular technological designation. The "6.0" was chosen simply to indicate that it was a new technology for American consumers. A DECT phone in the US operates at 1.9 GHz, and often replaced phones that used the 5.8 GHz frequency. It was decided that "1.9" might seem inferior to "5.8," despite this not being technically accurate, and so "6.0" was chosen for US marketing.

What are Some Common Abbreviations Used in Text Messaging

With the popularity of text-based communications, many abbreviations used in text messaging have become easily recognizable even by those who are not technologically savvy. Through text messaging, instant messaging, email and chat rooms, abbreviations such as BFF (best friends forever), LOL (lots of love or laugh out loud) and L8R (later) have become common place. But the list of abbreviations used in text messaging grows daily.

Many of the common abbreviations used in text messaging are shortened versions of expressions, such as AAMOF (as a matter of fact), IMHO (in my humble opinion), or PLMK (please let me know). Other common abbreviations that replace expressions include:

BBS: Be back soon
1. BBT: Be back tomorrow
2. BIB: Boss is back
3. CM: Call me
4. CYE: Check your email
5. DIKU: Do I know you?
6. F2F: Face to face
7. HB: Hurry back
8. JFF: Just for fun
9. KOTC: Kiss on the cheek
10. OMG: Oh my God!
11. OOTO: Out of the office
12. PSOS: Parents standing over shoulder
13. PU: That stinks!
14. SLAP: Sounds like a plan
15. TMB: Text me back
16. UGTBK: You’ve got to be kidding

Other abbreviations used in text messaging represent people or relationships, like BIL (brother in law), SO (significant other), or DWF (divorced white female). Some additional text message abbreviations that indicate people:

1. B/F: Boyfriend
2. BFAW: Best friend at work
3. DD: Dear daughter
4. DH: Dear husband
5. DS: Dear son
6. DW: Dear wife
7. G/F: Girlfriend
8. GRL: Girl

Even other abbreviations used in text messaging represent shortened versions of commonly used words, such as B4 (before), NE (any), or W? (why). Other abbreviations used in text messaging for frequently used words include:

1. AIGHT: Alright
2. GB: Goodbye
3. GL: Good luck
4. HV: Have
5. K: Okay
6. M8: Mate
7. ONL: Online
8. OVA: Over
9. PEEPS or PPL: People
10. PLS: Please
11. PZ: Peace
12. TTLY: Totally
13. W? Why
14. X: Kiss
15. Z: Zero

Some abbreviations used in text messaging incorporate symbols to represent words or phrases, like 411 (need information), 121 (private chat), and ?4U (question for you). Not as many common abbreviations start with symbols, but some others are <3 (represents a sideways heart), 4COL (for crying out loud), and 2G2BT (too good to be true).