What is a Thumb Drive

Computer users long complained that 3-inch floppy disks were too unstable, the ZIP drive not practical and CD-Rs not portable enough for data storage. The technology geeks solved this problem in ingenious fashion: the thumb drive. IBM came out with thumb drives in 1998, as a solution for replacing the less stable floppy disks. Their use caught on quickly, and as portable data storage has become more of an issue, thumb drives or flash drives skyrocketed in popularity. They can now be seen hanging on lanyards around the necks of computer users everywhere.

A thumb drive is portable memory storage. It is re-writeable and holds its memory without a power supply, unlike RAM. Thumb drives will fit into any USB port on a computer. They will also "hot swap," which means a user can plug the drive into a computer and will not have to restart it to access the thumb drive. The drives are small, about the size of a human thumb - hence, their name - and are very stable memory storage devices.

At first, some users saw their lack of compatibility with Windows 98 as a drawback of thumb drives, since so many users were still running that operating system when the drives were introduced. However, most thumb drives came equipped with software that installed a Win98 driver on the computer, enabling the user to connect a thumb drive. Installing the software took about 60 seconds. Thumb drives also pose security threats, since they are easily concealed. Users could copy proprietary information to them, or upload hacking software from them, all undetected by the system administrator. 

However, system administrators can also upload anti-virus software to an infected computer from a thumb drive, for instance, without risking the system servers. Their write speeds and read speeds only really come into play when users are running large applications from them. When the user is saving text documents or photos, for instance, these speeds are not nearly as important. Most thumb drives also have millions of re-write cycles and will store data for ten years before they need replacing.

The thumb drive is available in storage sizes of up to 16 gigabytes. Most people, however, will find that sizes of 256 megabytes to 512 MB will do nicely. If the person is storing mostly text, with few images, then an even smaller thumb drive may meet the need.

A thumb drive is available anywhere computer supplies are sold. They range in price from about US$15 to $75 or so for a large-capacity drive. They are stable, versatile, durable and portable data storage devices. As such they are ideal for almost any computer user who wants safe, long-term storage for a low price.

How Does Infrared Work

Infrared (IR) light is a wavelength of energy that is invisible to the human eye. The most common source of this energy is heat; objects can have their relative temperatures measured by how much of this energy they give off. Lower wavelengths or "near infrared" — closest to the visible light color red — are not hot, and are often used to transmit data in electronics. A remote control, for example, may use a particular wavelength of near infrared to communicate with a receiver, sending pulses of light that transmit a signal to the device, telling it what to do.

Description and Measurement

A form of energy, IR is part of the electromagnetic spectrum. This spectrum is comprised of radio waves; microwaves; infrared, visible, and ultraviolet light; x-rays; and gamma rays. Each form of energy is ordered by wavelength; infrared falls between microwaves and visible light waves because its waves are shorter than microwaves but longer than those of visible light.

The prefix infra comes from the Latin word which means "below;" the term means "below red," indicating its position in the electromagnetic spectrum. Visible light has a range of wavelengths that are manifested in the seven colors of the rainbow; red has the longest wavelength and violet has the shortest. Infrared, with wavelengths longer than the color red, is invisible to the human eye.

Just like with visible light, there are a range of wavelengths of IR. The International Commission on Illumination has divided it into three general sections based on the length of the wave and density. These groups are commonly known as near, medium, and far infrared, with near infrared being nearest to the visible light side of the spectrum and far, or long-wave, infrared being close to the microwave zone. There are uses for IR wavelengths in each group, from wireless communication to acting as heat source.

Applications of Infrared

Nearly all objects emit heat or energy, and one of the most easily discernible forms of energy is infrared. When an object is not hot enough to give off visible light, it emits most of its energy in the IR spectrum. It is this heat that affords IR many applications in almost every sector of life, including health, science, industry, art, and entertainment.

Converting infrared energy, also known as radiant heat, into an image that the human eye can see and understand is done with a process called thermal imaging. An IR camera is used to accurately measure the temperature of an object, which is then translated into color. For example, infrared imaging typically shows the warmest areas in a human body as red, followed by yellow, green, blue, and violet as the temperature decreases. By studying how body heat is distributed, thermal imaging can health professionals to analyze body tissue and fluid to detect injury or disease.

Infrared light is used in night vision equipment, allowing the user to see in the dark. Two types of night vision both use IR: thermal and image-intensifying. Thermal night vision allows the user to recognize people and objects by the heat pattern they emit. Intensifiers amplify existing light — including infrared — to allow the user to see.

As a way to measure temperature, IR is used in many different types of applications. The military uses infrared sensors to locate and track targets or to detect hidden land mines or arms caches. Infrared sensors on satellites are used for environmental monitoring, pinpointing areas of pollution, fire, or deforestation. Search and rescue operations use IR extensively to locate missing persons lost in the forest or jungle, as well as in collapsed buildings or at the site of other disasters.

Many remote control devices in homes use infrared. These remotes use infrared light to carry signals between a remote control transmitter and the device it's commanding. The transmitter sends out light in pulses, which are translated into binary codes that have corresponding commands. The receiver is positioned on the front of the device, where it receives these pulses of light and decodes them into binary data, which is understood by the microprocessor inside the apparatus. 

Many different types of scientists use infrared in their work, from astronomers use it to learn more about galaxies light years away to archaeologists who use it when studying ancient settlements. Infrared is being used to preserve, restore, and conserve valuable historical and artistic works as well; the invisible details of ancient fragments and images painted under paintings are being brought to light through the use of IR technology. In industry, thermal imaging is invaluable in testing and monitoring mechanical systems.

What is the Difference Between NTSC and PAL

Some Americans may have sent video home movies to a European relative, only to discover that the images are scrambled and the sound quality is very poor. This is caused by a major difference in broadcast formats used by the United States and many other countries. The United States favors a format called NTSC, which is short for National Television Standards Committee, while Europe, Australia and parts of Asia use a competing format called PAL, or Phase Alternating Line.

Most of us would not be able to recognize the difference between NTSC and PAL, but then again most of us aren't television broadcast engineers. The differences really start with the electrical power system behind the transmissions. In the United States and other countries, electrical power is generated at 60 hertz, so for technical reasons the NTSC signal is also sent out at 60 'fields' per second. Since most televisions use an interlaced system, this means that 30 lines of the image are sent out, followed by the alternating 30 lines. This line alternation happens so fast that it becomes undetectable, much like a film running through a projector. The result for an NTSC television is 30 frames of a complete image appearing every second.

Since Europe uses a 50 hertz power supply, the equivalent PAL lines go out at 50 fields per second, or 25 alternating lines. PAL televisions only produce 25 complete frames per second, which can cause some problems with the proper display of motion. Think of it as the 'silent movie effect', in which the actors seem to move a little faster because there are fewer frames showing movement. If a PAL movie is converted to an NTSC tape, 5 extra frames must be added per second or the action might seem jerky. The opposite is true for an NTSC movie converted to PAL. Five frames must be removed per second or the action may seem unnaturally slow.

Another difference between NTSC and PAL formats is resolution quality. PAL may have fewer frames per second, but it also has more lines than NTSC. PAL television broadcasts contain 625 lines of resolution, compared to NTSC's 525. More lines usually means more visual information, which equals better picture quality and resolution. Whenever an NTSC videotape is converted to PAL, black bars are often used to compensate for the smaller screen aspect, much like letterboxing for widescreen movies. 

When the NTSC format was first adopted in 1941, there was little discussion of color transmissions. When the technology for color television arrived, engineers had to create a broadcast method which would still allow owners of monochrome television sets to receive a picture. Color signals on the NTSC format are still not considered ideal by electronics experts. The PAL system, on the other hand, was created after the advent of color broadcasting, so color signals are much truer to the original image.

For most purposes, the difference between NTSC and PAL signals are negligible. A European television set won't work in the United States and an NTSC formatted DVD won't play on a PAL player. But many people own home movies which cannot be viewed on a competing format. For this reason, there are a number of companies which offer conversion kits from NTSC to PAL or PAL to NTSC. Some of these conversion methods can be time-consuming and variable in quality, but others provide an easy way to create a PAL video for a European relative or an NTSC DVD for a Canadian friend. Some electronic media outlets may also provide conversion services for a price.

What Is the Difference Between a Line Conditioner and a Surge Protector

The difference between a line conditioner and a surge protector mostly lies in their intended function. A line conditioner takes in power and modifies it based on the requirements of the machinery to which it is connected. A surge protector doesn't alter the power flowing through it at all, unless that power is over a certain amount. When the power exceeds the set amount, it blocks it from passing through. It is not uncommon for a line conditioner and a surge protector to be in the same unit.

Both a line conditioner and a surge protector are important parts of modern electronics. They protect the inner workings of devices, often without users even realizing. Many people go the extra step of placing these devices between the wall outlets and connected devices to create an additional layer of protection.

A line conditioner modifies voltage as it passes through. Some systems require very tight or nonstandard power tolerances. These devices use line conditioners to alter the power to meet their requirements. They are also a common method of prolonging the lifespan of electric devices, as the properly formed electricity creates less wear of the internal parts of the device.

Most electric systems have line conditioners built into them. These units are usually very small and integrated right into the circuit board inside the device. They monitor the voltage moving across the board and keep it within tolerance. Larger line conditioners exist, ranging from small ones in high-end surge protectors all the way to car-sized industrial units connected to factory machines.

Surge protectors prevent power overloads. When power exceeds a certain amount, they stop it from passing through. Different surge protectors do this in different ways, but the most common method is creating a shunt to a ground wire. 

This connection to the ground only happens when the power is prevented from passing through the unit; otherwise, the unit would constantly waste electricity. If a surge protector is improperly plugged in, such as through a two- or three-pronged adapter, it cannot send power to the ground. In this case, the surge protector may overload and catch on fire or even send the surge through to the connected device.

It isn't unusual for a line conditioner and a surge protector to exist in the same unit. Since these systems both work on passing voltage, it is logical for them to exist together. Some systems only possess a very advanced line conditioner that works as a surge protector when needed; this is common in battery backup systems. In either case, both a line conditioner and a surge protector are important aspects of safe electric device use.

Who Invented the Refrigerator

Refrigerators are an essential part of every modern kitchen. While just about every home makes use of a refrigerator, most consumers know nothing about the history of refrigeration and the invention of the refrigerator. The gradual creation of the modern refrigerator actually spans a process that began in the 18th century and culminated with the work of German engineer Carl von Linden in 1876.

The first efforts that eventually led to the modern refrigeration process that continues to form the basis for the fridges that grace kitchens all over the world today. William Cullen of the University of Glasgow first developed a process to create an artificial cooling medium in 1748. At the time, there did not appear to be much interest in applying the medium to use in commercial or home applications, so the process created little in the way of interest beyond the scientific community. It would take the better part of a century before someone would apply the basic principles discovered by Cullen and create a design for a refrigerating machine. 

Created in 1804, the design was the work of an American inventor by the name of Oliver Evans. However, no working prototype appeared until 1834. At that time, Jacob Perkins built a refrigeration machine that is often thought to be the forerunner of the modern refrigerator. A decade later, John Gorrie designed what is thought to be the first practical refrigerator. In 1844, Gorrie, a physician in the United State, constructed a working unit based on the design of Oliver Evans. Gorrie created the unit as a means of cooling the air in facilities he set aside for patients who were diagnosed with yellow fever. Many people credit Gorrie as being the individual who for all practical intents and purposes invented the refrigerator. 

Carl von Linden discovered and patented an improved method of liquefying gas in 1876, which made the process of manufacturing refrigerator models practical. Making use of such gases as ammonia, sulfur dioxide and methyl chloride, the new process formed the standard for cooling agents until the late 1920’s. By then, a number of accidents related to the use of these substances as cooling agents convinced manufacturers that a more stable element was needed. This effort led to the development of freon, which provided the standard for cooling agents for the bulk of the remainder of the 20th century, until the substance was leaked to damage to the ozone layer. 

From the simple working model created by John Gorrie in 1844 to the modern fridge units of today, the refrigerator has become one of the appliances that is an integral part of our lives. From storing our favorite foods to providing refreshing ice, the refrigerator is one device that most of us would not want to live without.

How Does a Television Work

A television produces a series of tiny dots on a screen that, when seen as a whole, appear as an image. Older televisions rely on a cathode-ray tube to produce images, and operate with an analog signal. As technology has advanced and broadcast signals transitioned from analog to digital, plasma and LCD (liquid crystal display) televisions were created. These TVs are more compact and have crisper pictures than their cathode-ray counterparts because they use a thin grid of pixels to create images rather than a vacuum tube.

The Eyes and the Brain

Most kinds of television work from the same basic principle. The tiny dots of light produced on the TV screen, called pixels, flash according to a specific pattern provided by the video signal. A person's eyes transmit this pattern to the brain, where it is interpreted as a recognizable image. The television set refreshes these patterns hundreds of times per second — faster than the human eye can see — which gives the illusion of movement.

The Cathode-Ray Tube

The cathode-ray tube (CRT), the oldest version of the television, consists of a vacuum tube with a narrow end and a wide end. The narrow end contains an ion gun, which shoots out a series of charged particles of electricity. A series of electromagnets guide the particles to specific points on the wide end of the tube, the screen that viewers look at. Phosphors, substances that light up when a charged electrical particle hits them, coat the screen's inner surface. The ion gun essentially sprays the image at the screen, much like a paint gun sprays paint onto a surface.

Different kinds of phosphors produce different colors, but for color television, only red, blue, and green are needed. Using these colors in various combinations and intensities can create all the colors the human eye can see. As energy travels from the ion gun to the phosphors, it is filtered to strike the exact point on the screen needed to produce a specific hue. In combination, all of these colored pixels create a color image.

Cathode-ray tubes are quite heavy due to the large amount of glass they contain, and relatively inefficient, especially when used in large-screen televisions. For this reason, new technologies were developed to make lighter sets with crisper images. In addition, the development of high definition (HD) digital broadcast signals made bigger screens more popular since the images were of higher quality. Plasma and LCD televisions were created in response.

The Plasma Screen

A plasma screen television consists of a number of tiny cells filled with neon and xenon gases. Each cell is linked to an electrode, which, when fired, excites the gases contained in the cell. The gases emit charge particles, much like the ion gun, that interact with phosphors coating the glass inside each cell. The phosphors light up, creating the image seen on the television screen. The large number of cells in a plasma screen makes for a great number of pixels, rendering a clearer and brighter image.

Compared to other technologies, plasma TVs produce some of deepest blacks, which means that the contrast ratio is very high. They also have very high refresh rates, so images with a lot of motion don't blur as they can on other televisions. If the image remains static, however, it can burn into the screen, creating a permanent discoloration; this is more common in older plasma TVs, and can also occur with CRT screens. Plasma screens can be set to be very bright, which requires a lot of electricity. They also tend to be thicker than LCD televisions, although much thinner than CRTs.

The LCD Screen

LCD televisions also use cells to create images. Rather than exciting gases as plasma TVs do, however, the cells contain a set of red, blue, and green filters covered by a layer of liquid crystals sandwiched between two pieces of glass. Depending on the display type, each cell is linked to either electrodes or thin film transistors (TFT), which trigger the necessary cells to create the image. A backlight — most often cold-cathode fluorescent lamp — lights up the screen so the image can be seen.

While LCDs are very light and thin, they are subject to "dead" pixels, where one or more cells on the screen do not change. Viewing LCD screens from an angle can also lower the picture quality. They have slower response times than plasma or CRT televisions as well, so images can "ghost" or blur in movement.

More recent versions of the LCD television use light-emitting diodes (LEDs) as the light source rather than cold-cathode fluorescent lamps. LED televisions require less electricity than regular LCD screens, and take up even less space. Also, LEDs generally emit a brighter white light, making these screens especially vivid.

What Is Cell Phone Etiquette

Cell phones have become an unavoidable part of modern life for many people, but their presence in so many places can lead to situations in which users are inconsiderate of others. Just as general rules of etiquette vary among cultures, so do rules of cell phone etiquette. Still, some basic principles cross cultural norms — common sense and courtesy are the cornerstones of polite cell phone use. Respecting public and personal space, maintaining privacy, and not disturbing others are some general principles a person should keep in mind when using a mobile phone.

Public vs. Private Use

Cell phone etiquette is usually at its most important in public spaces, where one loud talker can disturb a large number of people. How a person uses his or her phone in more private situations matters too, however, to those who are concerned with being considerate. Many people find it rude when someone takes a cell phone call on a date or during a private social engagement with others. Along the same lines, it's usually thought to be inconsiderate to take a call in the middle of a conversation; if the caller were there in person, he or she would likely wait to politely interrupt at a more appropriate time. When in a small group or one-on-one situation, it's best for someone receiving the call to not pick up unless it's an emergency.

Focus on the Situation, Not the Call

Public settings such as restaurants, waiting rooms, and subways are usually bad places for casual cell phone conversations. Unless the user is expecting an important call, it would be best to put the ringer on vibrate or silent mode and let any calls that do not need to be answered immediately go to voice mail. This is not only more considerate to other people in the public space, but it also helps the caller maintain his or her privacy by not divulging personal information in public.

It is also generally considered poor cell phone etiquette to stay on the phone when dealing with cashiers or customer service people. If using the phone in a supermarket or other store, the person should hang up before going to the checkout lane. In a casual restaurant, it's usually considered impolite to both the counter staff and the person on the other end of the line to stop in the middle of a conversation to place an order.

Although cars are usually considered private spaces, taking a call while driving is usually not a good idea. A number of jurisdictions ban cell phone use while driving unless a hands-free system is used. Even when a driver does not have to physically hold the phone, however, studies suggest that drivers who talk while they drive tend to focus less on the road and other cars and more on the conversation. Most calls can wait, but if one can't, it is safer for drivers to pull over before answering.

Important Phone Calls that Can't Wait

If the cell phone user thinks a call might be important, he or she should try to step outside or find a secluded area to take or return a call. For urgent calls that cannot be missed, polite cell phone users should try to keep their voices low and the conversations brief. If the call interrupts a conversation, it's best for the person to apologize before stepping away to answer.

Cell phones typically have sensitive microphones that can pick up a soft voice while blocking out ambient noise, so yelling into a cell phone is usually not necessary. When people are nearby, polite cell phone users try to keep their voices low and the tone unemotional and even. Arguing or airing dirty laundry in public is almost universally considered to be poor cell phone etiquette.

Maintaining a distance of at least 10 feet (3 meters) from the nearest person when talking on a cell phone is usually a good idea. No matter how quiet the conversation, if a person is standing too close to others, it may force them to overhear what is being said. If it's necessary for a person to speak loudly to be heard by the person he or she is speaking to due to a noisy location, it's probably not a good place to be taking the call.

Places Where the Phone Should Always Be Turned Off

In almost all cases, phones should be turned off in movie theaters, playhouses, observatories, or any other public place where an audience's attention is focused on a performance or event. A ringing phone or a conversation can be very disturbing to other audience members, who have often paid money for the experience. In some cases, performances have been stopped in progress as the performers wait for an audience member to leave or silence his or her phone.

Phones should be turned off anywhere in which silence is important and disruptions should be kept to an absolute minimum. This includes courthouses, libraries, places of worship, doctor's offices, weddings, and funerals, where a ringing phone could indicate a lack of respect. It's also best to turn off a phone during a job interview, as it can suggest that the person being interviewed is more concerned with personal issues than the job.

Ringtones

Loud and distinctive ringtones are good for catching the phone owner's attention, but they can be a major distraction to other patrons in a restaurant or theater. If a phone must be left on in a public space, the owner should put the ringer on silent or vibrate whenever possible to create the least disturbance. Turning the volume down or even changing the ringtone to one that is more subtle — such as the sound of bells ringing rather than the latest pop song — may also cause less of an interruption.

Texting and Surfing the Web

Using a smartphone to text someone or look something up online is usually appropriate in public spaces, as long as doing so does not disturb others. Smartphones often have very bright screens, and can even be used as flashlights in some cases, so using them in a dark environment like a movie theater can be very distracting. Watching videos or playing music without headphones is also likely to be a disruption in any public space, and should be avoided. Many smartphones also include games, which should only be played in public if they do not include loud sound effects or are likely to result in the player making a lot of physical movements or vocal reactions. 

Just like taking a phone call in the middle of a conversation would likely be considered impolite, focusing on the phone's screen to check sports scores or email while talking to others is usually bad cell phone etiquette. If an email or text must be responded to, the cell phone user should apologize and excuse himself to do so privately. Texting or surfing the Internet should never be done while driving.