Afghanistan（1）

Afghanistan, officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of 647,500 km2 (250,001 sq mi), making it the 42nd most populous and 41st largest nation in the world(SONY Vaio VGN-NS38M Battery). It is bordered by Pakistan in the southeast, Iran in the west, Turkmenistan, Uzbekistan and Tajikistan in the north, and China in the far northeast. The territory that now forms Afghanistan has been an ancient focal point of the Silk Road and human migration(SONY Vaio VGN-NS31S Battery). Archaeologists have found evidence of human habitation from as far back as 50,000 BC. Urban civilization may have begun in the area as early as 3,000 to 2,000 BC.

The country sits at an important geostrategic location that connects the Middle East with Central Asia and the Indian subcontinent, which has been home to various peoples through the ages. The land has witnessed many military conquests since antiquity, notably by Alexander the Great, Chandragupta Maurya, and Genghis Khan(SONY Vaio VGN-NS31M Battery). It has also served as a source from which local dynasties such as the Greco-Bactrians, Kushans, Saffarids, Ghaznavids, Ghorids, Timurids, Mughals and many others have established empires of their own.

The political history of modern Afghanistan begins in 1709 with the rise of the Pashtuns, when the Hotaki dynasty was established in Kandahar followed by Ahmad Shah Durrani's rise to power in 1747(SONY Vaio VGN-NS31Z Battery). The capital of Afghanistan was shifted in 1776 from Kandahar to Kabul and part of the Afghan Empire was ceded to neighboring empires by 1893. In the late 19th century, Afghanistan became a buffer state in the "Great Game" between the British and Russian empires. Following the third Anglo-Afghan war and the signing of the Treaty of Rawalpindi in 1919, the nation regained control over its foreign policy from the British(SONY Vaio VGN-NS21Z Battery).

After the 1978 Marxist revolution, the Soviet Union began a 10 year war in which over a million Afghans lost lives. This was followed by the Afghan civil war (1992–1996), the rise and fall of the extremist Taliban government and the 2001-present war. In December 2001(SONY Vaio VGN-NS21M Battery), the United Nations Security Council authorized the creation of the International Security Assistance Force (ISAF) to help maintain security in Afghanistan and assist the Karzai administration. While NATO and other countries are rebuilding war-torn Afghanistan, terrorist groups such as the Haqqani network with alleged support and guidance from Pakistan's Inter-Services Intelligence (ISI) spy network are actively involved in a nationwide Taliban-led insurgency(SONY Vaio VGN-NS21S Battery), which includes countless assassinations and suicide attacks. According to the United Nations, the insurgents were responsible for 75% of civilian casualties in 2010 and 80% in 2011.

Etymology

Main articles: Name of Afghanistan, Afghan (ethnonym), and Afghana

The name Afghānistān means "Land of the Afghans", which originates from the ethnonym "Afghan"(SONY Vaio VGN-NS12S Battery). The first part of the name "Afghan" designates the Pashtun people since ancient times, the founders and the largest ethnic group of Afghanistan. This name is mentioned in the form of Abgan in the 3rd century CE by the Sassanians and as Avagana (Afghana) in the 6th century CE by Indian astronomer Varahamihira(SONY Vaio VGN-NS12M Battery). A people called the Afghans are mentioned several times in a 10th century geography book, Hudud al-'alam, particularly where a reference is made to a village.

Saul, a pleasant village on a mountain. In it live Afghans.

Al-Biruni referred to them in the 11th century as various tribes living on the western frontier mountains of the Indus River, which would be the Sulaiman Mountains. Ibn Battuta, a famous Moroccan scholar visiting the region in 1333(SONY Vaio VGN-NS11Z Battery), writes: "We travelled on to Kabul, formerly a vast town, the site of which is now occupied by a village inhabited by a tribe of Persians called Afghans. They hold mountains and defiles and possess considerable strength, and are mostly highwaymen. Their principle mountain is called Kuh Sulayman."

Afghan soldiers of the Durrani Empire. The name "Afghaunistan" is written on this 1847 Lithograph by James Rattray(SONY Vaio VGN-NS11M Battery).

One prominent 16th century Persian scholar explains extensively about the Afghans. For example, he writes:

The men of Kábul and Khilj also went home; and whenever they were ques­tioned about the Musulmáns of the Kohistán (the mountains), and how matters stood there, they said, "Don't call it Kohistán, but Afghánistán; for there is nothing there but Afgháns and dis­turbances." (SONY Vaio VGN-NS11L Battery) Thus it is clear that for this reason the people of the country call their home in their own language Afghánistán, and themselves Afgháns.

—Firishta, 1560-1620 AD

It is widely accepted that the terms "Pashtun" and Afghan are synonyms. In the writings of the 17th-century Pashto poet Khushal Khan Khattak it is mentioned:

Pull out your sword and slay any one, that says Pashtun and Afghan are not one! Arabs know this and so do Romans: Afghans are Pashtuns, Pashtuns are Afghans(SONY Vaio VGN-NS11J Battery)!

The last part of the name, -stān is a suffix for "place", prominent in many languages of the region. The name "Afghanistan" is described by the 16th century Mughal Emperor Babur in his memoirs as well as by the later Persian scholar Firishta and Babur's descendants, referring to the traditional ethnic Afghan (Pashtun) territories between the Hindu Kush mountains and the Indus River(SONY Vaio VGN-NS11E Battery). In the early 19th century, Afghan politicians decided to adopt the name Afghanistan for the entire Afghan Empire after its English translation had already appeared in various treaties with Qajarid Persia and British India. In 1857, in his review of J.W. Kaye's The Afghan War, Friedrich Engels describes "Afghanistan" as(SONY Vaio VGN-NS10L Battery):

an extensive country of Asia between Persia and the Indies, and in the other direction between the Hindu Kush and the Indian Ocean. It formerly included the Persian provinces of Khorassan and Kohistan, together with Herat, Beluchistan, Cashmere, and Sinde, and a considerable part of the Punjab Its principal cities are Kabul, the capital, Ghuznee, Peshawer, and Kandahar(SONY Vaio VGN-NS10J Battery).

The Afghan kingdom was sometimes referred to as the Kingdom of Kabul, as mentioned by the British statesman and historian Mountstuart Elphinstone. Afghanistan was officially recognized as a sovereign state by the international community after the signing of the 1919 Treaty of Rawalpindi(SONY Vaio VGN-NS38M/W Battery).

Geography

Main article: Geography of Afghanistan

Topography

A landlocked mountainous country with plains in the north and southwest, Afghanistan is described as being located within South Asia or Central Asia. It is part of the Greater Middle East Muslim world, which lies between latitudes 29° N and 39° N, and longitudes 60° E and 75° E. The country's highest point is Noshaq(SONY Vaio VGN-NS38M/P Battery), at 7,492 metres (24,580 feet) above sea level. It has a continental climate with very harsh winters in the central highlands, the glaciated northeast (around Nuristan) and the Wakhan Corridor, where the average temperature in January is below −15 °C (5 °F), and hot summers in the low-lying areas of the Sistan Basin of the southwest, the Jalalabad basin in the east(SONY Vaio VGN-NS31Z/W Battery), and the Turkestan plains along the Amu River in the north, where temperatures average over 35 °C (95 °F) in July.

Snow-covered mountains of Afghanistan

Despite having numerous rivers and reservoirs, large parts of the country are dry. The endorheic Sistan Basin is one of the driest regions in the world. Afghanistan does not face water shortages because, aside from the usual rain falls, it receives plenty of snow during winter in the Hindu Kush and Pamir Mountains(SONY Vaio VGN-NS31Z/S Battery), and the melting snow in the spring season enters the rivers, lakes, and streams. However, two-thirds of the country's water flows into neighboring countries of Iran, Pakistan, and Turkmenistan. The state needs more than US$2 billion to rehabilitate its irrigation systems so that the water is properly managed(SONY Vaio VGN-NS31Z/P Battery).

scenic view in western Afghanistan

The northeastern Hindu Kush mountain range, in and around the Badakhshan Province of Afghanistan, is in a geologically active area where earthquakes may occur almost every year. They can be deadly and destructive sometimes, causing landslides in some parts or avalanche during winter. The last strong earthquake was in 1998(SONY Vaio VGN-NS31S/S Battery), which killed about 6,000 people in Badakhshan near Tajikistan. This was followed by the 2002 Hindu Kush earthquakes in which over 150 people of various regional countries were killed and over 1,000 injured. The 2010 earthquake left 11 Afghans dead, over 70 injured and more than 2,000 houses destroyed(SONY Vaio VGN-NS31M/W Battery).

The country's natural resources include: coal, copper, iron ore, lithium, uranium, rare earth elements, chromite, gold, zinc, talc, barites, sulfur, lead, marble, precious and semi-precious stones, natural gas, and petroleum among other things. In 2010, US and Afghan government officials estimated that untapped mineral deposits located in 2007 by the US Geological Survey are worth between $900 bn and $3 trillion(SONY Vaio VGN-NS31M/P Battery).

At 652,230 square kilometres (251,830 sq mi), Afghanistan is the world's 41st largest country, slightly bigger than France and smaller than Burma, about the size of Texas in the United States. It borders Pakistan in the south and east, Iran in the west, Turkmenistan, Uzbekistan and Tajikistan in the north, and China in the far east(SONY Vaio VGN-NS21Z/S Battery).

History

Main article: History of Afghanistan

History of Afghanistan

Timeline

Excavations of prehistoric sites by Louis Dupree and others suggest that humans were living in what is now Afghanistan at least 50,000 years ago, and that farming communities in the area were among the earliest in the world. An important site of early historical activities, many say that Afghanistan compares to Egypt in terms of the historical value of its archaeological sites(SONY Vaio VGN-NS21S/W Battery).

Afghanistan is at a unique nexus point where numerous civilizations have interacted and often fought. It has been home to various peoples through the ages, among them the ancient Iranian peoples who established the dominant role of Indo-Iranian languages in the region(SONY Vaio VGN-NS21S/S Battery). At multiple points, the land has been incorporated within large regional empires, among them the Achaemenid Empire, the Macedonian Empire, the Indian Maurya Empire, the Islamic Empire and the Sassanid Empire.

Many kingdoms have also risen to power in what is now Afghanistan, such as the Greco-Bactrians, Kushans, Hephthalites, Kabul Shahis, Saffarids, Samanids, Ghaznavids, Ghurids, Kartids, Timurids, Mughals, and finally the Hotaki and Durrani dynasties that marked the political origins of the modern state of Afghanistan(SONY Vaio VGN-NS21M/W Battery).

Pre-Islamic period

Main article: Pre-Islamic period of Afghanistan

Archaeological exploration done in the 20th century suggests that the geographical area of Afghanistan has been closely connected by the culture of and trade with neighboring regions to the east, west, and north. Artifacts typical of the Paleolithic, Mesolithic, Neolithic, Bronze, and Iron ages have been found in Afghanistan(SONY Vaio VGN-NS21M/P Battery). Urban civilization may have begun as early as 3000 BCE, and the early city of Mundigak (near Kandahar in the south of the country) may have been a colony of the nearby Indus Valley Civilization.

A 5th century BC carving of Median and Achaemenid soldiers, at a time when the region was known as Ariana(SONY Vaio VGN-NS12S/S Battery).

After 2000 BCE, successive waves of semi-nomadic people from Central Asia moved south into the boundaries of modern Afghanistan, among them were many Indo-European-speaking Indo-Iranians. These tribes later migrated further south to India, west to what is now Iran, and towards Europe via the area north of the Caspian. The region was called Ariana(SONY Vaio VGN-NS12M/W Battery).

The ancient Zoroastrianism religion is believed by some to have originated in what is now Afghanistan between 1800 and 800 BCE, as its founder Zoroaster is thought to have lived and died in Balkh. Ancient Eastern Iranian languages may have been spoken in the region around the time of the rise of Zoroastrianism(SONY Vaio VGN-NS12M/S Battery). By the middle of the 6th century BCE, the Achaemenid Persians overthrew the Medians and incorporated Afghanistan (Arachosia, Aria and Bactria) within its boundaries. An inscription on the tombstone of King Darius I of Persia mentions the Kabul Valley in a list of the 29 countries he had conquered(SONY Vaio VGN-NS11Z/S Battery).

Bilingual (Greek and Aramaic) edict by Emperor Ashoka from the 3rd century BCE was discovered in the southern city of Kandahar.

Alexander the Great and his Macedonian army arrived in the area of Afghanistan in 330 BCE after defeating Darius III of Persia a year earlier in the Battle of Gaugamela. Following Alexander's brief occupation, the successor state of the Seleucid Empire controlled the area until 305 BCE when they gave much of it to the Indian Maurya Empire as part of an alliance treaty(SONY Vaio VGN-NS11ZR/S Battery).

Alexander took these away from the Aryans and established settlements of his own, but Seleucus Nicator gave them to Sandrocottus (Chandragupta), upon terms of intermarriage and of receiving in exchange 500 elephants(SONY Vaio VGN-NS11S/S Battery).

—Strabo, 64 BC – 24 AD

The Mauryans brought Buddhism from India and controlled the area south of the Hindu Kush until about 185 BCE when they were overthrown. Their decline began 60 years after Ashoka's rule ended, leading to the Hellenistic reconquest of the region by the Greco-Bactrians. Much of it soon broke away from the Greco-Bactrians and became part of the Indo-Greek Kingdom(SONY Vaio VGN-NS11SR/S Battery). The Indo-Greeks had been defeated and expelled by the Indo-Scythians in the late 2nd century BCE.

During the 1st century BCE, the Parthian Empire subjugated the region, but lost it to their Indo-Parthian vassals. In the mid to late 1st century CE the vast Kushan Empire, centered in modern Afghanistan, became great patrons of Buddhist culture(SONY Vaio VGN-NS11M/S Battery). The Kushans were defeated by the Sassanids in the 3rd century CE. Although various rulers calling themselves Kushanshas (generally known as the Indo-Sassanids) continued to rule at least parts of the region, they were probably more or less subject to the Sassanids.

The late Kushans were followed by the Kidarite Huns who, in turn, were replaced by the short-lived but powerful Hephthalites(SONY Vaio VGN-NS11MR/S Battery), as rulers in the first half of the 5th century. The Hephthalites were defeated by Khosrau I in CE 557, who re-established Sassanid power in Persia. However, in the 6th century CE, the successors to the Kushans and Hepthalites established a small dynasty in Kabulistan called Kabul Shahi(SONY Vaio VGN-NS11L/S Battery).

Islamization and Mongol invasion

Main articles: Islamic conquest of Afghanistan and Mongol invasion of Central Asia

Built during the Ghurids era, the Friday Mosque of Herat or Masjid Jami is one of the oldest mosques in Afghanistan.

Between the fourth and nineteenth centuries, much of modern Afghanistan was known by the regional name as Khorasan. Two of the four main capitals of Khorasan (i.e. Balkh, Merv, Nishapur and Herat) are now located in modern Afghanistan(SONY Vaio VGN-NS11J/S Battery), while Kandahar, Zabulistan, Ghazni and Kabulistan formed the frontier between Khorasan and Hindustan. The land inhabited by the Afghan tribes (i.e. ancestors of modern Pashtuns) was called Afghanistan, which loosely covered the area between the Hindu Kush and the Indus River, with the Sulaiman Mountains being the center(SONY Vaio VGN-NS11E/S Battery).

A miniature from Padshahnama depicting the surrender of the Shia Safavid garrison of Kandahar in 1638 to the Mughals, which was re-taken in 1650 during the Mughal-Safavid war.

Arab Muslims brought the message of Islam to the western area of what is now Afghanistan during the 7th century and began spreading eastward, some of the native inhabitants they encountered accepted it while others revolted(SONY Vaio VGN-NS11ER/S Battery). Afghanistan at that time was Zoroastrian, Buddhist and Hindu, with smaller populations of Jews, Christians and others. The Shahi rulers lost their Kabul capital in around 870 AD after it was conquered by the Saffarid Muslims of Zaranj. Later, the Samanids extended their Islamic influence into the Hindu Kush area from Bukhara in the north. It is reported that Muslims and non-Muslims lived side by side(SONY Vaio VGN-NS115N/S Battery).

"Kábul has a castle celebrated for its strength, accessible only by one road. In it there are Musulmáns, and it has a town, in which are infidels from Hind."

—Istahkrí, 921 AD

Afghanistan became one of the main centers in the Muslim world during the Islamic Golden Age. By the 11th century the Ghaznavids had finally Islamized all of the remaining non-Muslim areas, with the exception of the Kafiristan region(SONY Vaio VGN-NS110E/W Battery). They were replaced by the Ghurids who expanded and advanced the already powerful empire. In 1219 AD, Genghis Khan and his Mongol barbarians overran the region. His troops are said to have annihilated the Khorasanian cities of Herat and Balkh. The destruction caused by the Mongols depopulated major cities and forced many of the locals to revert to an agrarian rural society(SONY Vaio VGN-NS110E/S Battery). Mongol rule continued with the Ilkhanate in the northwest while the Khilji dynasty controlled the Afghan tribal areas south of the Hindu Kush, until the invasion of Timur who established the Timurid dynasty in 1370. During the Ghaznavid, Ghurid, and Timurid eras, Afghanistan produced many fine Islamic architectural monuments as well as numerous scientific and literary works(SONY Vaio VGN-NS110E/L Battery).

Babur, a descendant of both Timur and Genghis Khan, arrived from Central Asia and captured Kabul from the Arghun dynasty, and from there he began to seize control of the central and eastern territories of Afghanistan. He remained in Kabulistan until 1526 when he and his army invaded Delhi in India to replace the Afghan Lodi dynasty with the Mughal Empire(SONY Vaio VGN-NS10L/S Battery). From the 16th century to the early 18th century, Afghanistan was part of three regional kingdoms: the Khanate of Bukhara in north, the Shi'a Safavids in the west and the remaining larger area was ruled by the Delhi Sultanate.

Afghan nation-state

Hotaki dynasty and the Durrani Empire

Main articles: Hotaki dynasty and Durrani Empire

Mirwais Hotak revolted against the Safavid rule and declared the Kandahar region an independent Afghan kingdom in 1709, which was later expanded by his son Mahmud to include Persia(SONY Vaio VGN-NS10J/S Battery).

Mirwais Hotak, seen as Afghanistan's George Washington, successfully rebelled against the Persian Safavids in 1709. He overthrew and killed Gurgin Khan, and made the Afghan region independent from Persia. By 1713, Mirwais had decisively defeated two larger Persian armies, one was led by Khusraw Khán (nephew of Gurgin) and the other by Rustam Khán(SONY Vaio VGN-NS10E/S Battery). The armies were sent by Sultan Husayn, the Shah in Isfahan (now Iran), to re-take control of the Kandahar region. Mirwais died of a natural cause in 1715 and was succeeded by his brother Abdul Aziz followed by his son Mahmud. In 1722, Mahmud led an Afghan army to the Persian capital of Isfahan(Sony VAIO VGN-SR94VS battery), sacked the city after the Battle of Gulnabad and proclaimed himself King of Persia. The Persians were disloyal to the Afghan rulers, and after the massacre of thousands of religious scholars, nobles, and members of the Safavid family, the Hotaki dynasty was ousted from Persia after the 1729 Battle of Damghan(Sony VAIO VGN-SR94HS battery).

In 1738, Nader Shah and his Afsharid forces captured Kandahar from Shah Hussain Hotaki, at which point the incarcerated 16 year old Ahmad Shah Durrani was freed and made the commander of Nader Shah's four thousand Abdali Afghans. From Kandahar they set out to conquer India, passing through Ghazni(Sony VAIO VGN-SR94GS battery), Kabul, Lahore and ultimately plundering Delhi after the Battle of Karnal. Nader Shah and his army abandoned Delhi but took with them huge treasure, which included the Koh-i-Noor and Darya-ye Noor diamonds. After the death of Nader Shah in 1747, the Afghans chose Ahmad Shah Durrani as their head of state(Sony VAIO VGN-SR94FS battery). Regarded as the founder of modern Afghanistan, Durrani and his Afghan army conquered the entire present-day Afghanistan, Pakistan, Khorasan and Kohistan provinces of Iran, along with Delhi in India. He defeated the Sikhs of the Maratha Empire in the Punjab region nine times, one of the biggest battles was the 1761 Battle of Panipat.

The last stand of the British 44th Foot, during the massacre of Elphinstone's Army, in January 1842(Sony VAIO VGN-SR93YS battery).

In October 1772, Ahmad Shah Durrani died of a natural cause and was buried at a site now adjacent to the Shrine of the Cloak in Kandahar. He was succeeded by his son, Timur Shah Durrani, who transferred the capital of Afghanistan from Kandahar to Kabul in 1776. After Timur Shah's death in 1793, the Durrani throne was passed down to his son Zaman Shah followed by Mahmud Shah, Shuja Shah and others(Sony VAIO VGN-SR93PS battery).

The Afghan Empire was under threat in the early 1800s by the Sikhs in the east and the Persians in the west. The western province of Herat was invaded by the Persians but was successfully fought off by Fateh Khan, brother of Dost Mohammad Khan. The Sikhs, under Ranjit Singh, invaded Afghanistan's Khyber Pakhtunkhwa region in 1809(Sony VAIO VGN-SR93JS battery). Fateh Khan was defeated by Hari Singh Nalwa in the 1813 Battle of Attock. Fateh Khan had installed 21 of his brothers in positions of power throughout the Afghan Empire. After his death, they rebelled and divided up the provinces of the empire between themselves. During this turbulent period, Afghanistan had many temporary rulers until Dost Mohammad Khan's take over in 1826(Sony VAIO VGN-SR93DS battery). The Afghan army descended in 1837 through the Khyber Pass on Sikh forces at Jamrud. The Sikhs held off the Afghan offensive for over a week – the time it took reinforcements to reach Jamrud from Lahore. By this time the British had reached the area from the east, and in 1839 the First Anglo-Afghan War or better known as the Great Game was initiated(Sony VAIO VGN-SR92US battery).

Receiver (radio)

A radio receiver is an electronic circuit that receives its input from an antenna, uses electronic filters to separate a wanted radio signal from all other signals picked up by this antenna, amplifies it to a level suitable for further processing(SONY Vaio VGN-FW32J Battery), and finally converts through demodulation and decoding the signal into a form usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc(SONY Vaio VGN-FW17W Battery).

Early broadcast radio receiver--wireless Truetone model from about 1940

In consumer electronics, the terms radio and radio receiver are often used specifically for receivers designed for the sound signals transmitted by radio broadcasting services – historically the first mass-market radio application(SONY Vaio VGN-FW31E Battery).

Types of radio receivers

Various types of radio receivers may include:

Consumer audio and high fidelity audio receivers and AV receivers used by home stereo listeners and audio and home theatre system enthusiasts(SONY Vaio VGN-FW139E Battery).

Communications receivers, used as a component of a radio communication link, characterized by high stability and reliability of performance(SONY Vaio VGN-FW139E/H Battery).

Simple crystal radio receivers (also known as a crystal set) which operate using the power received from radio waves(SONY Vaio VGN-FW465J Battery).

Satellite television receivers, used to receive television programming from communication satellites in geosynchronous orbit(SONY Vaio VGN-FW31M Battery).

Specialized-use receivers such as telemetry receivers that allow the remote measurement and reporting of information(SONY VAIO VGN-FZ21E Battery).

Measuring receivers (also: measurement receivers) are calibrated laboratory-grade devices that are used to measure the signal strength of broadcasting stations, the electromagnetic interference radiation emitted by electrical products, as well as to calibrate RF attenuators and signal generators(SONY VAIO VGN-FZ21Z Battery).

Scanners are specialized receivers that can automatically scan two or more discrete frequencies, stopping when they find a signal on one of them and then continuing to scan other frequencies when the initial transmission ceases. They are mainly used for monitoring VHF and UHF radio systems(SONY VAIO VGN-FZ21J Battery).

Internet radio device

Consumer audio receivers

In the context of home audio systems, the term "receiver" often refers to a combination of a tuner, a preamplifier, and a power amplifier all on the same chassis. Audiophiles will refer to such a device as an integrated receiver(SONY Vaio VGN-FW11 Battery), while a single chassis that implements only one of the three component functions is called a discrete component(SONY Vaio VGN-FW11M Battery). Some audio purists still prefer three discreet units - tuner, preamplifier and power amplifier - but the integrated receiver has, for some years, been the mainstream choice for music listening(SONY Vaio VGN-FW11S Battery). The first integrated stereo receiver was made by the Harman Kardon company, and came onto the market in 1958. It had undistinguished performance, but it represented a breakthrough to the "all in one" concept of a receiver(SONY Vaio VGN-FW21E Battery), and rapidly improving designs gradually made the receiver the mainstay of the marketplace. Many radio receivers also include a loudspeaker(SONY Vaio VGN-FW21J Battery).

Hi-Fi / Home theater

Main article: Home cinema

Today AV receivers are a common component in a high-fidelity or home-theatre system. The receiver is generally the nerve centre of a sophisticated home-theatre system providing selectable inputs for a number of different audio components like turntables(SONY Vaio VGN-FW21L Battery), compact-disc players and recorders, and tape decks ( like video-cassette recorders) and video components (DVD players and recorders, video-game systems, and televisions) (SONY Vaio VGN-FW21M Battery).

With the decline of vinyl discs, modern receivers tend to omit inputs for turntables, which have separate requirements of their own. All other common audio/visual components can use any of the identical line-level inputs on the receiver for playback(SONY VGP-BPS13Q Battery), regardless of how they are marked (the "name" on each input is mostly for the convenience of the user.) For instance, a second CD player can be plugged into an "Aux" input, and will work the same as it will in the "CD" input jacks(SONY VGP-BPS13B/Q Battery).

Some receivers can also provide signal processors to give a more realistic illusion of listening in a concert hall. Digital audio S/PDIF and USB connections are also common today(SONY VGN NR11S/S battery). The home theater receiver, in the vocabulary of consumer electronics, comprises both the 'radio receiver' and other functions, such as control, sound processing, and power amplification. The standalone radio receiver is usually known in consumer electronics as a tuner(SONY VGN NR11M/S battery).

Some modern integrated receivers can send audio out to seven loudspeakers and an additional channel for a subwoofer and often include connections for headphones. Receivers vary greatly in price, and support stereophonic or surround sound(SONY VGN NR11Z/S battery). A high-quality receiver for dedicated audio-only listening (two channel stereo) can be relatively inexpensive; excellent ones can be purchased for $300 United States or less. Because modern receivers are purely electronic devices with no moving parts unlike electromechanical devices like turntables and cassette decks(SONY VGN NR11Z/T battery), they tend to offer many years of trouble-free service. In recent years, the home theater in a box has become common, which often integrates a surround-capable receiver with a DVD player. The user simply connects it to a television, perhaps other components, and a set of loudspeakers(SONY VGP-BPS13A/Q Battery).

Portable radios

Portable radios include simple transistor radios that are typically monoaural and receive the AM, FM, and/or short wave broadcast bands. FM, and often AM, radios are sometimes included as a feature of portable DVD/CD, MP3 CD, and USB key players, as well as cassette player/recorders(SONY VGP-BPS21/S Battery).

AM/FM stereo car radios can be a separate dashboard mounted component or a feature of in car entertainment systems(SONY VGP-BPS21 Battery).

A Boombox (or Boom-box)—also sometimes known as a Ghettoblaster or a Jambox, or (in parts of Europe) as a "radio-cassette"—is a name given to larger portable stereo systems capable of playing radio stations and recorded music, often at a high level of volume(SONY VGP-BPS21B Battery).

Self-powered portable radios, such as clockwork radios are used in developing nations or as part of an emergency preparedness kit(SONY VGP-BPS21A/B Battery).

History of radio receivers

For the history of radio transmitting, see radio.

For the inventors of radio technology, see Invention of radio.

Early development

While James Clerk Maxwell was the first person to prove electromagnetic waves existed, in 1887 a German named Heinrich Hertz demonstrated these new waves by using spark gap equipment to transmit and receive radio or "Hertzian waves", as they were first called(SONY pcga-bp2ea battery). The experiments were not followed up by Hertz. The practical applications of the wireless communication and remote control technology were implemented by Nikola Tesla(SONY VAIO PCG-5K1L battery).

The world's first radio receiver (thunderstorm register) was designed by Alexander Stepanovich Popov, and it was first seen at the All-Russia Exhibition 1896. He was the first to demonstrate the practical application of electromagnetic (radio) waves, although he did not care to apply for a patent for his invention(SONY VAIO PCG-6W2L battery).

A device called a coherer became the basis for receiving radio signals. The first person to use the device to detect radio waves was a Frenchman named Edouard Branly, and Oliver Lodge popularised it when he gave a lecture in 1898 in honour of Hertz(SONY VAIO PCG-7112L battery). Lodge also made improvements to the coherer. Many experimenters at the time believed that these new waves could be used to communicate over great distances and made significant improvements to both radio receiving and transmitting apparatus(SONY VAIO PCG-8Z1L battery). In 1895 Marconi demonstrated the first viable radio system, leading to transatlantic radio communication in December 1901. The honor was later contested as he was found to be using equipment and designs of other experimenters that held the patents at that time(SONY VAIO PCG-8Z2L battery).

John Ambrose Fleming's development of an early thermionic valve to help detect radio waves was based upon a discovery of Thomas Edison's (called "The Edison effect", which essentially modified an early light bulb) (SONY VAIO PCG-8Y2L battery). Fleming called it his "oscillation valve" because it acted in the same way as water valve in only allowing flow in one direction. While Fleming's valve was a great stride forward it would take some years before thermionic, or vacuum tube technology was fully adopted(SONY VAIO PCG-8Y1L battery).

Around this time work on other types of detectors started to be undertaken and it resulted in what was later known as the cat's whisker. It consisted of a crystal of a material such as galena with a small springy piece of wire brought up against it(SONY VAIO PCG-7Z2L battery). The detector was constructed so that the wire contact could be moved to different points on the crystal, and thereby obtain the best point for rectifying the signal and the best detection. They were never very reliable as the "whisker" needed to be moved periodically to enable it to detect the signal properly(SONY VAIO PCG-7Z1L battery).

Valves (Tubes)

An American named Lee de Forest, a competitor to Marconi, set about to develop receiver technology that did not infringe any patents to which Marconi had access. He took out a number of patents in the period between 1905 and 1907 covering a variety of developments that culminated in the form of the triode valve in which there was a third electrode called a grid(SONY VAIO PCG-7133L battery). He called this an audion tube. One of the first areas in which valves were used was in the manufacture of telephone repeaters, and although the performance was poor, they gave significant improvement in long distance telephone receiving circuits(SONY VAIO PCG-7113L battery).

With the discovery that triode valves could amplify signals it was soon noticed that they would also oscillate, a fact that was exploited in generating signals. Once the triode was established as an amplifier it made a tremendous difference to radio receiver performance as it allowed the incoming signals to be amplified(SONY VAIO PCG-6W3L battery). One way that proved very successful was introduced in 1913 and involved the use of positive feedback in the form of a regenerative detector. This gave significant improvements in the levels of gain that could be achieved(SONY VAIO PCG-7111L battery), greatly increasing selectivity, enabling this type of receiver to outperform all other types of the era. With the outbreak of the First World War, there was a great impetus to develop radio receiving technology further(SONY VAIO PCG-6W1L battery). An American named Irving Langmuir helped introduce a new generation of totally air-evacuated "hard" valves. H. J. Round undertook some work on this and in 1916 he produced a number of valves with the grid connection taken out of the top of the envelope away from the anode connection(SONY VAIO PCG-6V1L battery).

Autodyne and superheterodyne

By the 1920s, the tuned radio frequency receiver (TRF) represented a major improvement in performance over what had been available before, it still fell short of the needs for some of the new applications(SONY VAIO PCG-6S3L battery). To enable receiver technology to meet the needs placed upon it a number of new ideas started to surface. One of these was a new form of direct conversion receiver(SONY VAIO PCG-6S2L battery). Here an internal or local oscillator was used to beat with the incoming signal to produce an audible signal that could be amplified by an audio amplifier(SONY VAIO PCG-5J2L battery).

H. J. Round developed a receiver he called an autodyne in which the same valve was used as a mixer and an oscillator, Whilst the set used fewer valves it was difficult to optimise the circuit for both the mixer and oscillator functions(SONY VAIO PCG-5L1L battery).

The next leap forward in receiver technology was a new type of receiver known as the superheterodyne, or supersonic heterodyne receiver(SONY VAIO PCG-5K2L battery). A Frenchman named Lucien Levy was investigating ways in which receiver selectivity could be improved and in doing this he devised a system whereby the signals were converted down to a lower frequency where the filter bandwidths could be made narrower(SONY VAIO PCG-5J1L battery). A further advantage was that the gain of valves was considerably greater at the lower frequencies used after the frequency conversion, and there were fewer problems with the circuits bursting into oscillation(SONY VAIO PCG-5G3L battery).

The idea for developing a receiver with a fixed intermediate frequency amplifier and filter is credited to Edwin Armstrong of the United States. Working for the American Expeditionary Force in Europe during 1918, Armstrong thought that if the incoming signals was mixed with a variable frequency oscillator (the "local oscillator")(SONY VGP-BPS13B/S Battery), a lower-frequency fixed tuned amplifier could be used. Armstrong's original receiver consisted of a total of eight vacuum tubes. Several tuned circuits could be cascaded to improve selectivity, and being set on a fixed frequency they did not all need to be changed in line with one another(SONY VGP-BPS13S Battery). The filters could be preset and left correctly tuned. Armstrong was not the only person working on the idea of a superheterodyne receiver(SONY VGP-BPS13AS Battery). Alexander Meissner in Germany had taken out a patent for the idea six months before Armstrong, but since Meissner did not prove the idea in practice, and he did not build a superheterodyne radio, the invention is credited to Armstrong(SONY VGP-BPS13A/S Battery).

The need for the increased performance of the superheterodyne receiver was first experienced in North America, and by the late 1920s most radio sets were superheterodyne receivers(Sony VAIO VGN-FZ15G Battery). However, in Europe the number of broadcast stations did not start to rise as rapidly until later. Even so, by the mid-1930s virtually all receiving sets in Europe as well were using the superheterodyne principle. In 1926, the tetrode valve was introduced, and enabled further improvements in performance(Sony VAIO VGN-FZ15T Battery).

War and postwar developments

Military HF receiver, type BC-224-D (1942)

In 1939 the outbreak of war gave a new impetus to receiver development. During this time a number of classic communications receivers were designed(SONY VGP-BPS13/B Battery). Some like the National HRO are still sought by enthusiasts today and although they are relatively large by today's standards, they can still give a good account of themselves under current crowded band conditions(Dell N3010 Battery). In the late 1940s the transistor was discovered. Initially the devices were not widely used because of their expense, and the fact that valves were being made smaller, and performed better. However by the early 1960s portable transistor broadcast receivers (transistor radios) were hitting the market place(Dell INSPIRON 1764 battery). These radios were ideal for broadcast reception on the long and medium wave bands. They were much smaller than their valve equivalents, they were portable and could be powered from batteries. Although some valve portable receivers were available(Dell INSPIRON 1564 battery), batteries for these were expensive and did not last for long. The power requirements for transistor radios were very much less, resulting in batteries lasting for much longer and being considerably cheaper(Dell INSPIRON 1464 battery).

Semiconductors

Further developments in semiconductor technology led to the introduction of the integrated circuit in the late 1950s. This enabled radio receiver technology to move forward even further. Integrated circuits enabled high performance circuits to be built for less cost, and significant amounts of space could be saved(Dell INSPIRON 1520 battery).

As a result of these developments new techniques could be introduced. One of these was the frequency synthesizer that was used to generate the local oscillator signal for the receiver. By using a synthesizer it was possible to generate a very accurate and stable local oscillator signal(Dell INSPIRON 1420 battery). Also the ability of synthesizers to be controlled by microprocessors meant that many new facilities could be introduced apart from the significant performance improvements offered by synthesizers(Dell INSPIRON E1505 battery).

Digital technologies

Receiver technology had been advancing gradually and regularly. Many of the functions performed by a analogue electronics can be performed by software instead. The benefit is that software is not affected by temperature, physical variables, electronic noise and manufacturing defects(Dell INSPIRON 1525 battery).

While today's radios are amazing pieces of modern technology, filled with low- power, high performance, integrated circuits crammed into the smallest spaces, the basic principle of the radio receiver is practically always the superheterodyne one(SONY VGP-BPS13B/B Battery), the same idea which was developed by Edwin Armstrong back in 1918. For really high-performance receivers, such as satellite communications receivers and military/naval receivers(SONY VGP-BPS13 Battery), two-stage ("double conversion") and even three-stage ("triple conversion") superheterodyne processing is frequently used. Single-conversion receivers are rather simple-minded in their nature(HP PAVILION DV6000 battery).

DSP technology

DSP technology, short for digital signal processing, is the use of digital means to process signals and is coming into wide use in modern shortwave receivers. It is the basis of many areas of modern technology including cell phones(SONY VAIO VGN-FZ31B Battery), CD players, video recorders and computers. A digital signal is essentially a stream or sequence of numbers that relay a message through some sort of medium such as a wire(SONY VAIO VGN-FZ31M Battery). The primary benefit of DSP hardware in shortwave receivers is the ability to tailor the bandwidth of the receiver to current reception conditions and to the type of signal being listened to. A typical analog only receiver may have a limited number of fixed bandwidths, or only one, but a DSP receiver may have 40 or more individually selectable filters(SONY VAIO VGN-FZ31J Battery).

PC controlled radio receivers

"PC radios", or radios that are designed to be controlled by a standard PC are controlled by specialized PC software using a serial port connected to the radio. A "PC radio" may not have a front-panel at all, and may be designed exclusively for computer control, which reduces cost(SONY VAIO VGN-FZ31E Battery).

Some PC radios have the great advantage of being field upgradable by the owner. New versions of the DSP firmware can be downloaded from the manufacturer's web site and uploaded into the flash memory of the radio(Sony Vaio VGN-FZ31S battery). The manufacturer can then in effect add new features to the radio over time, such as adding new filters, DSP noise reduction, or simply to correct bugs(SONY VAIO VGN-FZ31z Battery).

A full-featured radio control program allows for scanning and a host of other functions and, in particular, integration of databases in real-time, like a "TV-Guide" type capability. This is particularly helpful in locating all transmissions on all frequencies of a particular broadcaster, at any given time(SONY VAIO VGN-FZ38M Battery). Some control software designers have even integrated Google Earth to the shortwave databases, so it is possible to "fly" to a given transmitter site location with a click of a mouse. In many cases the user is able to see the transmitting antennas where the signal is originating from(SONY VAIO VGN-FZ210CE Battery).

Radio control software

The field of software control of PC radios has grown rapidly in the last several years, with developers making a number of advances. Since the Graphical User Interface or GUI interface PC to the radio has unlimited flexibility(SONY VAIO VGN-FZ160 Battery), any number of new features can be added by the software designer.Features that can be found in advanced control software programs today include a band table, GUI controls corresponding to traditional radio controls, local time clock and a UTC clock, signal strength meter(SONY VAIO VGN-FZ21 Battery), an ILG database for shortwave listening with lookup capability, scanning capability, text-to-speech interface, and integrated Conference Server(SONY VAIO VGN-FZ410 Battery).

Software-defined radios

Main article: Software-defined radio

The next level in radio / software integration are so-called pure "software defined radios". The distinction here is that all filtering, modulation and signal manipulation is done in software, usually by a PC soundcard or by a dedicated piece of DSP hardware(SONY VAIO VGN-FZ21m Battery). There may be a minimal RF front-end or traditional radio that supplies an IF to the SDR. SDR's can go far beyond the usual demodulation capability of typical, and even high-end DSP shortwave radios(SONY VAIO VGN-FZ18m Battery). They can for example, record large swaths of the radio spectrum to a hard drive for "playback" at a later date. The same SDR that one minute is demodulating a simple AM broadcast may also be able to decode an HDTV broadcast in the next(SONY VAIO VGN-FZ11m Battery). A well known open-source project called GNU Radio is dedicated to evolving a high-performance SDR. All the source code for this SDR is freely downloadable and modifiable by anyone(SONY VAIO VGN-FZ11z Battery).

The industry's 10 best IT certifications

IT certifications boast numerous benefits. They bolster resumes, encourage higher salaries, and assist in job retention. But which IT certifications are best(SONY VGP-BPS21/S Battery)?

Technology professionals generate much debate over just that question. Many claim vendor-specific programs best measure a candidate’s skills, while others propose vendor-independent exams are the only worthy way of measuring real-world expertise(SONY VGP-BPS21 Battery). Still other observers believe the highest-level accreditations — Microsoft’s MCSE or new Architect Series certification, Cisco’s CCIE, etc. — are the only credentials that truly hold value(SONY VGP-BPS21B Battery).

Myself, I don’t fully subscribe to any of those mindsets. The best IT certification for you, after all, is likely to be different from that for another technology professional with different education, skills, and goals working at a different company in a different industry(SONY VGP-BPS21A/B Battery). For that reason, when pursuing any professional accreditation, you should give much thought and care to your education, experience, skills, goals, and desired career path(SONY pcga-bp2ea battery).

Once a career road map is in place, selecting a potential certification path becomes much easier. And that’s where this list of the industry’s 10 best IT certifications comes into play. While this list may not include the 10 best accreditations for you, it does catalog 10 IT certifications that possess significant value for a wide range of technology professionals(SONY VAIO PCG-5K1L battery).

#1: MCITP

The new-generation Microsoft Certified IT Professional credential, or MCITP for short, is likely to become the next big Microsoft certification. Available for a variety of fields of expertise — including database developer(SONY VAIO PCG-6W2L battery), database administrator, enterprise messaging administrator, and server administrator — an MCITP validates a professional’s proven job-role capabilities. Candidates must pass several Microsoft exams that track directly to their job role before earning the new designation(SONY VAIO PCG-7112L battery).

As with Microsoft’s other new-generation accreditations, the MCITP certification will retire when Microsoft suspends mainstream support for the platforms targeted within the MCITP exams. By matching the new certification to popular job roles(SONY VAIO PCG-8Z1L battery), as has been done to some extent with CompTIA’s Server+ (server administrator), Project+ (project manager), and A+ (desktop support) certifications, Microsoft has created a new certification that’s certain to prove timely, relevant, and valuable(SONY VAIO PCG-8Z2L battery).

#2: MCTS

The new-generation Microsoft Certified Technology Specialist (MCTS) helps IT staff validate skills in installing, maintaining, and troubleshooting a specific Microsoft technology. The MCTS certifications are designed to communicate the skills and expertise a holder possesses on a specific platform(SONY VAIO PCG-8Y2L battery).

For example, candidates won’t earn an MCTS on SQL Server 2008. Instead, they’ll earn an MCTS covering SQL Server business intelligence (MCTS: SQL Server 2008 Business Intelligence), database creation (MCTS: SQL Server 2008, Database Development), or SQL server administration (MCTS: SQL Server 2008, Implementation and Maintenance) (SONY VAIO PCG-8Y1L battery).

These new certifications require passing multiple, tightly targeted exams that focus on specific responsibilities on specific platforms. MCTS designations will expire when Microsoft suspends mainstream support for the corresponding platform. These changes, as with other new-generation Microsoft certifications, add value to the accreditation(SONY VAIO PCG-7Z2L battery).

#3: Security+

Security continues to be a critical topic. That’s not going to change. In fact, its importance is only going to grow. One of the quickest ways to lose shareholder value, client confidence, and sales is to suffer a data breach. And no self-respecting technology professional wants to be responsible for such a breach(SONY VAIO PCG-7Z1L battery).

CompTIA’s Security+ accreditation provides a respected, vendor-neutral foundation for industry staff (with at least two years of experience) seeking to demonstrate proficiency with security fundamentals(SONY VAIO PCG-7133L battery). While the Security+ accreditation consists of just a single exam, it could be argued that any IT employee charged with managing client data or other sensitive information should, at a minimum, possess this accreditation(SONY VAIO PCG-7113L battery). The importance of ensuring staff are properly educated as to systems security, network infrastructure, access control, auditing, and organizational security principles is simply too important to take for granted(SONY VAIO PCG-6W3L battery).

#4: MCPD

There’s more to information technology than just administration, support, and networking. Someone must create and maintain the applications and programs that power organizations. That’s where the new-generation Microsoft Certified Professional Developer (MCPD) credential comes into play(SONY VAIO PCG-7111L battery).

The MCPD accreditation measures a developer’s ability to build and maintain software solutions using Visual Studio 2008 and Microsoft .NET Framework 3.5. Split into three certification paths (Windows Developer 3.5, ASP.NET Developer 3.5, and Enterprise Applications Developer 3.5) (SONY VAIO PCG-6W1L battery), the credential targets IT professionals tasked with designing, optimizing, and operating those Microsoft technologies to fulfill business needs.

A redesigned certification aimed at better-measuring real-world skills and expertise, the MCPD will prove important for developers and programmers(SONY VAIO PCG-6V1L battery). Besides requiring candidates to pass several exams, the MCPD certification will retire when Microsoft suspends mainstream support for the corresponding platform. The change is designed to ensure the MCPD certification remains relevant, which is certain to further increase its value(SONY VAIO PCG-6S3L battery).

#5: CCNA

The Cisco Certified Internetwork Expert (CCIE) accreditation captures most of the networking company’s certification glory. But the Cisco Certified Network Associate (CCNA) might prove more realistic within many organizations(SONY VAIO PCG-6S2L battery).

In a world in which Microsoft and Linux administrators are also often expected to be networking experts, many companies don’t have the budgets necessary to train (or employ) a CCIE(SONY VAIO PCG-5J2L battery). But even small and midsize corporations can benefit from having their technology professionals earn basic proficiency administering Cisco equipment, as demonstrated by earning a CCNA accreditation(SONY VAIO PCG-5L1L battery).

As smaller companies become increasingly dependent upon remote access technologies, basic Cisco systems skills are bound to become more important. Although many smaller organizations will never have the complexity or workload necessary to keep a CCIE busy, Cisco’s CCNA is a strong accreditation for technology professionals with a few years’ experience seeking to grow and improve their networking skills(SONY VAIO PCG-5K2L battery).

#6: A+

Technology professionals with solid hardware and support skills are becoming tougher to find. There’s not much glory in digging elbow-deep into a desktop box or troubleshooting Windows boot errors. But those skills are essential to keeping companies running(SONY VAIO PCG-5J1L battery).

Adding CompTIA’s A+ certification to a resume tells hiring managers and department heads that you have proven support expertise. Whether an organization requires desktop installation, problem diagnosis, preventive maintenance(SONY VAIO PCG-5G3L battery), or computer or network error troubleshooting, many organizations have found A+-certified technicians to be more productive than their noncertified counterparts.

Changes to the A+ certification, which requires passing multiple exams, are aimed at keeping the popular credential relevant(SONY VAIO PCG-5G2L battery). Basic prerequisite requirements are now followed by testing that covers specific fields of expertise (such as IT, remote support, or depot technician). The accreditation is aimed at those working in desktop support, on help desks, and in the field, and while many of these staffers are new to the industry, the importance of an A+ certification should not be overlooked(SONY VGP-BPS13B/S Battery).

#7: PMP

Some accreditations gain value by targeting specific skills and expertise. The Project Management Professional (PMP) certification is a great example(SONY VGP-BPS13S Battery).

The Project Management Institute (PMI), a nonprofit organization that serves as a leading membership association for project management practitioners, maintains the PMP exam(SONY VGP-BPS13AS Battery). The certification measures a candidate’s project management expertise by validating skills and knowledge required to plan, execute, budget, and lead a technology project. Eligible candidates must have five years of project management experience or three years of project management experience and 35 hours of related education(SONY VGP-BPS13A/S Battery).

As organizations battle tough economic conditions, having proven project scheduling, budgeting, and management skills will only grow in importance. The PMI’s PMP credential is a perfect conduit for demonstrating that expertise on a resume(Sony VAIO VGN-FZ15G Battery).

#8: MCSE/MCSA

Even years after their introduction, Microsoft Certified Systems Engineer (MCSE) and Microsoft Certified Systems Administrator (MCSA) credentials remain valuable. But it’s important to avoid interpreting these accreditations as meaning the holders are all-knowing gurus, as that’s usually untrue(Sony VAIO VGN-FZ15T Battery).

In my mind, the MCSE and MCSA hold value because they demonstrate the holder’s capacity to complete a long and comprehensive education, training, and certification program requiring intensive study. Further, these certifications validate a wide range of relevant expertise (from client and server administration to security issues) on specific, widely used platforms(SONY VGP-BPS13/B Battery).

Also important is the fact that these certifications tend to indicate holders have been working within the technology field for a long time. There’s no substitute for actual hands-on experience(Dell N3010 Battery). Many MCSEs and MCSAs hold their certifications on Windows 2000 or Windows Server 2003 platforms, meaning they’ve been working within the industry for many years. While these certifications will be replaced by Microsoft’s new-generation credentials, they remain an important measure of foundational skills on Windows platforms(Dell INSPIRON 1764 battery).

#9: CISSP

As mentioned with the Security+ accreditation earlier, security is only going to grow in importance. Whatever an organization’s mission, product, or service, security is paramount(Dell INSPIRON 1564 battery).

(ISC)², which administers the Certified Information Systems Security Professional (CISSP) accreditation, has done well building a respected, vendor-neutral security certification. Designed for industry pros with at least five years of full-time experience, and accredited by the American National Standards Institute (ANSI) (Dell INSPIRON 1464 battery), the CISSP is internationally recognized for validating a candidate’s expertise with operations and network and physical security, as well as their ability to manage risk and understand legal compliance responsibilities and other security-related elements(Dell INSPIRON 1520 battery).

#10: Linux+

While pursuing my first Microsoft certification 10 years ago, I remember debating the importance of Linux with several telecommunications technicians. They mocked the investment I was making in learning Microsoft technologies. These techs were confident Linux was going to displace Windows(Dell INSPIRON 1420 battery).

Well, didn’t happen. Linux continues to make inroads, though. The open source alternative is an important platform. Those professionals who have Linux expertise and want to formalize that skill set will do well adding CompTIA’s Linux+ certification to their resumes(Dell INSPIRON E1505 battery).

The vendor-neutral exam, which validates basic Linux client and server skills, is designed for professionals with at least six to 12 months of hands-on Linux experience. In addition to being vendor-neutral, the exam is also distribution neutral (meaning the skills it covers work well whether a candidate is administering Red Hat, SUSE, or Ubuntu systems) (Dell INSPIRON 1525 battery).

Let the debate begin

Technology professionals almost always have strong reactions when debating certification’s value. Listing the top 10 certifications leaves room, of course, for only 10 credentials. That means many favorite and popular designations(SONY VGP-BPS13B/B Battery), such as HIPAA and Sarbanes-Oxley (SOX) certifications, have been necessarily omitted. Other important accreditations, including those for VoIP providers and from PC manufacturers, Red Hat, and even Apple, have also been left out here(SONY VGP-BPS13 Battery).

Which certifications would you leave off this list and which would you add in their place? Join the discussion and share the logic behind your choices(HP PAVILION DV6000 battery).

Modern technology is changing the way our brains work

Human identity, the idea that defines each and every one of us, could be facing an unprecedented crisis.It is a crisis that would threaten long-held notions of who we are, what we do and how we behave. It goes right to the heart - or the head - of us all. This crisis could reshape how we interact with each other, alter what makes us happy, and modify our capacity for reaching our full potential as individuals (Sony Vaio VGN-FZ battery).

And it's caused by one simple fact: the human brain, that most sensitive of organs, is under threat from the modern world.

Unless we wake up to the damage that the gadget-filled, pharmaceutically-enhanced 21st century is doing to our brains, we could be sleepwalking towards a future in which neuro-chip technology blurs the line between living and non-living machines, and between our bodies and the outside world (Sony VGP-BPS8 battery).

It would be a world where such devices could enhance our muscle power, or our senses, beyond the norm, and where we all take a daily cocktail of drugs to control our moods and performance (Sony VGP-BPL9 battery).

Already, an electronic chip is being developed that could allow a paralysed patient to move a robotic limb just by thinking about it. As for drug manipulated moods, they're already with us - although so far only to a medically prescribed extent (Sony VGP-BPL11 battery).

Increasing numbers of people already take Prozac for depression, Paxil as an antidote for shyness, and give Ritalin to children to improve their concentration. But what if there were still more pills to enhance or "correct" a range of other specific mental functions?

What would such aspirations to be "perfect" or "better" do to our notions of identity, and what would it do to those who could not get their hands on the pills? Would some finally have become more equal than others, as George Orwell always feared (Sony VGP-BPL15 battery)?

Of course, there are benefits from technical progress - but there are great dangers as well, and I believe that we are seeing some of those today.

I'm a neuroscientist and my day-to-day research at Oxford University strives for an ever greater understanding - and therefore maybe, one day, a cure - for Alzheimer's disease (Sony VGN-FZ460E battery).

But one vital fact I have learnt is that the brain is not the unchanging organ that we might imagine. It not only goes on developing, changing and, in some tragic cases, eventually deteriorating with age, it is also substantially shaped by what we do to it and by the experience of daily life. When I say "shaped", I'm not talking figuratively or metaphorically; I'm talking literally. At a microcellular level, the infinitely complex network of nerve cells that make up the constituent parts of the brain actually change in response to certain experiences and stimuli (SONY VAIO VGN-FZ4000 Battery).

The brain, in other words, is malleable - not just in early childhood but right up to early adulthood, and, in certain instances, beyond. The surrounding environment has a huge impact both on the way our brains develop and how that brain is transformed into a unique human mind (Sony VGP-BPS3 battery).

Of course, there's nothing new about that: human brains have been changing, adapting and developing in response to outside stimuli for centuries.

What prompted me to write my book is that the pace of change in the outside environment and in the development of new technologies has increased dramatically. This will affect our brains over the next 100 years in ways we might never have imagined.

Our brains are under the influence of an ever- expanding world of new technology: multichannel television, video games, MP3 players, the internet, wireless networks, Bluetooth links - the list goes on and on (Sony Vaio VGN-FZ21M battery ).

But our modern brains are also having to adapt to other 21st century intrusions, some of which, such as prescribed drugs like Ritalin and Prozac, are supposed to be of benefit, and some of which, such as widelyavailable illegal drugs like cannabis and heroin, are not (Apple A1281 battery).

Electronic devices and pharmaceutical drugs all have an impact on the micro- cellular structure and complex biochemistry of our brains. And that, in turn, affects our personality, our behaviour and our characteristics. In short, the modern world could well be altering our human identity (Apple M9848LL/A battery).

Three hundred years ago, our notions of human identity were vastly simpler: we were defined by the family we were born into and our position within that family. Social advancement was nigh on impossible and the concept of "individuality" took a back seat.

That only arrived with the Industrial Revolution, which for the first time offered rewards for initiative, ingenuity and ambition. Suddenly, people had their own life stories - ones which could be shaped by their own thoughts and actions. For the first time, individuals had a real sense of self (Apple A1189 battery).

But with our brains now under such widespread attack from the modern world, there's a danger that that cherished sense of self could be diminished or even lost.

Anyone who doubts the malleability of the adult brain should consider a startling piece of research conducted at Harvard Medical School. There, a group of adult volunteers, none of whom could previously play the piano, were split into three groups (Apple M8665G/A battery).

The first group were taken into a room with a piano and given intensive piano practise for five days. The second group were taken into an identical room with an identical piano - but had nothing to do with the instrument at all.

And the third group were taken into an identical room with an identical piano and were then told that for the next five days they had to just imagine they were practising piano exercises (Apple 661-2183 battery).

The resultant brain scans were extraordinary. Not surprisingly, the brains of those who simply sat in the same room as the piano hadn't changed at all.

Equally unsurprising was the fact that those who had performed the piano exercises saw marked structural changes in the area of the brain associated with finger movement.

But what was truly astonishing was that the group who had merely imagined doing the piano exercises saw changes in brain structure that were almost as pronounced as those that had actually had lessons. "The power of imagination" is not a metaphor, it seems; it's real, and has a physical basis in your brain (HP PAVILION DV2000 Battery).

Alas, no neuroscientist can explain how the sort of changes that the Harvard experimenters reported at the micro-cellular level translate into changes in character, personality or behaviour. But we don't need to know that to realise that changes in brain structure and our higher thoughts and feelings are incontrovertibly linked (HP PAVILION DV3000 Battery).

What worries me is that if something as innocuous as imagining a piano lesson can bring about a visible physical change in brain structure, and therefore some presumably minor change in the way the aspiring player performs, what changes might long stints playing violent computer games bring about? That eternal teenage protest of 'it's only a game, Mum' certainly begins to ring alarmingly hollow (Dell INSPIRON 1420 Battery).

Already, it's pretty clear that the screen-based, two dimensional world that so many teenagers - and a growing number of adults - choose to inhabit is producing changes in behaviour. Attention spans are shorter, personal communication skills are reduced and there's a marked reduction in the ability to think abstractly (Dell Inspiron E1505 Battery).

This games-driven generation interpret the world through screen-shaped eyes. It's almost as if something hasn't really happened until it's been posted on Facebook, Bebo or YouTube (Dell Latitude D620 Battery).

Add that to the huge amount of personal information now stored on the internet - births, marriages, telephone numbers, credit ratings, holiday pictures - and it's sometimes difficult to know where the boundaries of our individuality actually lie. Only one thing is certain: those boundaries are weakening (Dell Inspiron 6000 battery).

And they could weaken further still if, and when, neurochip technology becomes more widely available. These tiny devices will take advantage of the discovery that nerve cells and silicon chips can happily co-exist, allowing an interface between the electronic world and the human body. One of my colleagues recently suggested that someone could be fitted with a cochlear implant (devices that convert sound waves into electronic impulses and enable the deaf to hear) and a skull-mounted micro- chip that converts brain waves into words (Toshiba PA3535U-1BRS battery).

Then, if both devices were connected to a wireless network, we really would have arrived at the point which science fiction writers have been getting excited about for years. Mind reading!

He was joking, but for how long the gag remains funny is far from clear (ACER Aspire 3020 Battery).

Today's technology is already producing a marked shift in the way we think and behave, particularly among the young.

I mustn't, however, be too censorious, because what I'm talking about is pleasure. For some, pleasure means wine, women and song; for others, more recently, sex, drugs and rock 'n' roll; and for millions today, endless hours at the computer console (ACER Aspire 3000 Battery).

But whatever your particular variety of pleasure (and energetic sport needs to be added to the list), it's long been accepted that 'pure' pleasure - that is to say, activity during which you truly "let yourself go" - was part of the diverse portfolio of normal human life. Until now, that is (ACER Aspire 5020 Battery).

Now, coinciding with the moment when technology and pharmaceutical companies are finding ever more ways to have a direct influence on the human brain, pleasure is becoming the sole be-all and end-all of many lives, especially among the young.

We could be raising a hedonistic generation who live only in the thrill of the computer-generated moment, and are in distinct danger of detaching themselves from what the rest of us would consider the real world (ASUS A3000 Battery).

This is a trend that worries me profoundly. For as any alcoholic or drug addict will tell you, nobody can be trapped in the moment of pleasure forever. Sooner or later, you have to come down.

I'm certainly not saying all video games are addictive (as yet, there is not enough research to back that up), and I genuinely welcome the new generation of "brain-training" computer games aimed at keeping the little grey cells active for longer (ASUS Eee PC 900 Battery).

As my Alzheimer's research has shown me, when it comes to higher brain function, it's clear that there is some truth in the adage "use it or lose it".

However, playing certain games can mimic addiction, and that the heaviest users of these games might soon begin to do a pretty good impersonation of an addict.

Throw in circumstantial evidence that links a sharp rise in diagnoses of Attention Deficit Hyperactivity Disorder and the associated three-fold increase in Ritalin prescriptions over the past ten years with the boom in computer games and you have an immensely worrying scenario (ASUS Eee PC 1000HE Battery).

But we mustn't be too pessimistic about the future. It may sound frighteningly Orwellian, but there may be some potential advantages to be gained from our growing understanding of the human brain's tremendous plasticity. What if we could create an environment that would allow the brain to develop in a way that was seen to be of universal benefit (IBM ThinkPad R50 battery)?

I'm not convinced that scientists will ever find a way of manipulating the brain to make us all much cleverer (it would probably be cheaper and far more effective to manipulate the education system). And nor do I believe that we can somehow be made much happier - not, at least, without somehow anaesthetising ourselves against the sadness and misery that is part and parcel of the human condition (Fujitsu Lifebook S6120 battery).

When someone I love dies, I still want to be able to cry.

But I do, paradoxically, see potential in one particular direction. I think it possible that we might one day be able to harness outside stimuli in such a way that creativity - surely the ultimate expression of individuality - is actually boosted rather than diminished.

I am optimistic and excited by what future research will reveal into the workings of the human brain, and the extraordinary process by which it is translated into a uniquely individual mind (COMPAQ Presario M2000 Battery).

But I'm also concerned that we seem to be so oblivious to the dangers that are already upon us.

Well, that debate must start now. Identity, the very essence of what it is to be human, is open to change - both good and bad. Our children, and certainly our grandchildren, will not thank us if we put off discussion much longer (COMPAQ Presario R3000 Battery).