Thursday, January 17, 2013

Happy Birthday to U

1989 marks the 200th anniversary of the establishment of uranium as an element, and its naming. In 1989 Martin Heinrich Klaproth (1743-1817) a German apothecary turned chemist postulated the existence of a new element in pitchblende, previously considered an ore of iron and zinc. In fact, so sure was he that he even named it uranium, after the newly discovered planet Uranus (in 1781, by Herschel). M. Klaproth was a self-taught chemist who went on to become Professor of Chemistry at the University of Berlin in 1810. In quantitative analytical chemistry he was a precise worker, introducing corrections for impurities of reagents and apparatus faults. He used flint and agate mortars for their inertness. Klaproth begun by dissolving pitchblende in nitric acid, to which he added potash, getting a yellow precipitate. This precipitate was soluble in excess potash. When the precipitate was dried to constant weight, it was found to be small greenish yellow crystals in hexagonal prisms. Convinced that these were of the compound of a new element, he tried to isolate the metal. When Klaproth obtained a black, lustrous powder on the bottom of his Crucible, he thought he had the metal. He was mistaken. We now know this to be the oxide.

So, although uranium managed to find its way into the textbooks of chemistry, the metal was not yet available. Six years after Klaproth's death, J. Arfvedson, a Swedish pupil of Berzelius tried to reduce a dark green oxide of uranium with hydrogen. The reaction yielded a brown powder, which he took to be the metal. This was because Arfvedson had started with U3O8, which he believed was the lower oxide of uranium. He obtained UO2, which he therefore thought was the metal itself.

It was left to Eugène-Melchior Péligot in 1841 to isolate the metal with the new reducing methods of the time. He heated anhydrous uranium chloride with potassium in a platinum crucible, and obtained a black metallic powder with properties noticeably different from the black powder got by Klaproth.

Although the first ingot of the metal was prepared by A. Noissan in May 1896, (who melted it in a high temperature electric furnace) uranium still did not still become as important as it is in the present century. True, its properties were studied and its atomic mass measured; but the atomic mass was wrongly determined to be 120, which gave Dmitri Mendeleev trouble in placing it in the periodic table correctly. He originally placed it in the third group of his table as the heavy analogue of aluminum. But since the properties were different from what they were expected to be, Mendeleev proposed a revaluation, and finally placed it in Group VI under tungsten, which made it the heaviest and last of the naturally occurring elements of the periodic table.

Before the importance of the metal was realized in the modern sense, its salts were used even in cheap ceramics and glassware to give colors ranging from pale yellow to green. During the First World War and shortly after (1914-1926) it was used as a carbide former or hardening agent in tool steels, since tungsten and molybdenum were scarce. Several tons of ferro-uranium containing 30% uranium were produced for this purpose.

Uranium is a radioactive metal. This was discovered by Antoine Henri Becquerel in 1896 while doing an experiment to find out whether phosphorescent materials emit X-rays. When a photographic plate got exposed through black paper on a cloudy day through the agency of the crystals he was using for the experiment, Becquerel concluded that some unknown rays from the crystals had caused the exposure. This prompted him to analyze the crystals and find a trace of uranium to which he attributed the phenomenon. Thus it was uranium that led to the discovery of radioactivity.

In 1938, the Germans Otto Hahn and Fritz Strassman produced the first artificial nuclear fission reaction using uranium. Four years later, Enrico Fermi and his co-workers at the University of Chicago made the first nuclear pile containing uranium, which supported a controlled chain reaction. This of course led to the nuclear reactor and on the bleak side, the atomic bomb.

Uranium is obtained from its major ore, pitchblende or uraninite, which although rare, is the richest source. This black mineral with a pitchy luster has oxides of uranium and also traces of thorium, yttrium, lead, radium, and helium. It is found in Canada, Zaire, Czechoslovakia, and France. Uranium is also concentrated from ores containing gold and silver, which are the primary products. Another ore is carnotite and very poor sources are some shales and phosphate rocks. In fact, these are so poor that only because phosphate is extracted from them that it is practicable to extract uranium.

Uranium­235 supports a chain reaction easily, so it has to be concentrated to be used, (its occurrence is 0.71% naturally) up to 90% for nuclear weapons. Basically three methods are used:

  1.       The Gaseous Diffusion Method: Here, gaseous compounds of uranium (UF6) are passed through porous barriers where the U-235 fraction being lighter passes through more easily. If this process is repeated, relatively high proportions of U-235 can be obtained over the much more abundant U-238.
  2.       The Centrifugal Method: Uses rapidly rotating cylinders to separate the two gaseous fractions by centrifugation.
  3.       The Spectroscopic Method: This employs two lasers lasing at such frequencies, that while one excites the U-235 atom, the other ionizes it. The U-255 is then separated electrostatically.

After enrichment, the uranium fuel is fabricated, that is converted to UO2 and packed into cylindrical pellets which are placed in hollow stainless steel rods for use as reactor fuel. Although U-238 is not easily fissionable, it is not without its uses: fast neutrons in breeder reactors convert it to U-239 which beta-decays to neptunium and further to plutonium-239. Pu-239 is also a much-used nuclear fuel.

Thus, in these 200 years, uranium has seen a slow, then rapid rise in the uses to which it is put. Also, the work of many scientists has gone into giving us the picture that we now see: miraculously potent in its energy production, yet threateningly dangerous in radiation and nuclear warheads.

Thursday, May 24, 2012

Counterweights of Copley Square

Sualeh Fatehi

The Boston Public Library building, and the Trinity Church, on opposite sides of Copley Square, are both fine examples of Boston architecture. They add an imposing grandeur to this opening in Boston's busy streets. Copley Square allows tourists and busy office workers alike enough space to take in and admire the entire buildings. In the last half of the nineteenth century, the Back Bay was reclaimed from the sea, and developed with majestic public buildings. When built, the church and the library were seen as keystones in what would be a plan to bring cultural and scientific institutions into Boston.

Trinity Church
The Trinity Church was designed in a competition set out by the flamboyant preacher Phillip Brooks, and his congregation. Henry Hobson Richardson's firm Gambrill and Richardson won the competition, and Richardson moved from New York to Brookline to work on the church. Boston is where he developed his trademark style, Richardsonian Romanesque, of which the Trinity Church is the epitome.

The Boston Public Library was designed in 1888, during a period of popularity of classical design, when American Neoclassicism was popular. It was designed by the firm of McKim, Mead, and White shortly after Richardson's death. McKim, Mead, and White were the intellectual heirs of Richardson. Both Charles Follen McKim and Henry Hobson Richardson trained at Ecole des Beaux Arts in Paris after studying at Harvard University. McKim was a draftsman for Richardson during the Brattle Square Unitarian Church project.

Boston Public Library
Although the Boston Public Library is very different in style, and serves a different purpose than the church across the square from it, it is a building of great weight and significance. The Boston Public Library was designed as "a palace for the people and dedicated to the advancement of learning", and modeled on the Venetian palazzo of the Renaissance. In some sense, the square grey building is a quiet foil to the more colorful and ornate exterior of the Trinity Church, its counterweight at the other end of Copley Square.

The Trinity Church is decorated in polychromatic stone, which over the arches forms a checkerboard pattern of pink Monson granite, the main building material, and red Longmeadow sandstone. The Boston Public Library is more staid, at least on the exterior, with its light granite façade. The use of granite turned the tide of the "brown decades" in Boston architecture. However, the Library has a hidden inner courtyard, which was designed by McKim to resemble the interior courtyard of Bramante's Palazza della Cancelleria at the Vatican. The courtyard is in yellow stone, which forms a surprising contrast to the grey exterior. Just as the courtyard forms the quiet and serene interior of Library, the Church's Greek cross plan makes for a large interior space conducive to spiritual reflection.
Trinity Church is articulated with round-headed Romanesque arches. The Richardsonian Romanesque style draws on the visual strength of rusticated raw rock faces, with structural features like arches and lintels made of a different type of stone. In contrast to Trinity Church's deliberately unfinished look, the Library has smooth granite walls, topped with a copper creneau, and cast iron sconces.

Boston's Two State Houses

Sualeh Fatehi
4/29/2006

The City of Boston has the distinction of having not one, but two State Houses. Both of these buildings are noble and beautiful, and designed to attract the attention of even a first time visitor to Boston. The Old State House is elaborately decorated in English Gregorian, while the current State House, with its prominent dome lead Oliver Wendell Holmes to declare that it was the hub of the solar system.

Old State House
The Old State House is one of the oldest surviving public buildings in Boston. Though central in the old city, it is still pivotal, occupying an island in a traffic junction, in the midst of later Federal period, and even modern buildings. The Old State House was built in 1713 to house the government offices of the Massachusetts Bay Colony on the site of Boston's first Town House of 1657. It was built by William Payne, builder. The architect, however, is unknown.
The present State House is located at the top of Beacon Hill. Its golden dome is visible from afar, and like the Old State House, it is in a prominent position, and built on what was once the John Hancock's cow pastures. The original architect was America's first professional architect, Charles Bulfinch, this being his first professional commission in Boston, in 1787. (The national capitol in Washington DC and the state capitols of Connecticut and Maine are also Bulfinch's designs.) The State House building has been expanded since it was built in 1798.

Old State House
The new brick building of the Old State House, that replaced the wooden structure that burnt down in 1711, is in the typical Georgian style of the day, though more ornate than most. The windows are in expensive glass panes of twelve over twelve. Typically Georgian are the string courses found at intervals for horizontal relief in the building. The brickwork is English bond. The British emblems of the Lion and the Unicorn adorn the East face of the building. The East side has a stepped pediment, showing the Dutch influence on British architecture, along with the segmental arch. The Governor's Council Chamber was located upstairs on the east corner of the building, looking on Long Wharf (now State Street) and the harbor. The second floor was where the Massachusetts Assembly met.
Charles Bulfinch's design for the State House was inspired by Somerset House, Sir William Chambers' design for the naval command in England. Bulfinch designed the State House in a simplified neoclassical style, by smoothening its form for red brick. The resulting Federal style building is an ordered, geometrical, symmetrical building which is imposing without being too ornate. Typical of neoclassical design are the elaborate columns starting on the second floor, a pediment, and a vast shingled dome. Single Maine pine tree trunks, carved on site, were turned into fluted Corinthian columns. The dome was intended to make the structure stand out among its squat, square neighbors. The cupola is surmounted by a pine cone indicating the importance of lumber to the New England economy. Elements of the Federal style are apparent in the recessed arches of the main floor, with their subdued pilasters that complement the columns in the center. The lintels have a raised keystone, and a balustrade goes all around the building, curtaining the many chimneys of the original design. Also Federal is the diminishing fenestration that gives the building an appearance of greater height. The lowest floor is the most plain, with flat arches that support the upper storey. A white string course runs broken through the arches. The main entrance hall, the Doric Hall is a large room dominated by ten Doric columns.

The Old State House building has undergone many architectural and structural changes, including the addition of a subway station in the basement that John Hancock once rented. The earthquake of 1755 dislodged many bricks, and S-ties mark the places where the walls had to be secured.

State House
The State House has had its share of problems, and its expansions too. The impressive thirty-foot-high dome began to leak just four years after being built. Rain and snow caused the wooden shingles to rot in places. Paul Revere's foundry was hired to make the dome watertight by sheathing it with copper. Over time, the State House has needed more space for government offices. A large extension, built of yellow brick, was added to the back of the Bulfinch State House between 1889 and 1895. Yellow was the color in vogue at the time, and the extension was in yellow brick to match the yellow-painted bricks of the original building. It was designed by Charles Brigham, who made extensive use of marble, wrought iron, and carved wood paneling in the elegant interior. The balustrades on the upper floor carried the outline of the Bulfinch building, and harmonized the whole. The next addition of the two white Vermont marble wings to the east and west of the State House was completed in 1917. They were designed by William Chapman, Robert Andrew, and Clipson Sturgis. Though the exterior of this building is bleak, it is again the balustrades that unify it to the whole.

State House
Just as the Old State House is an anachronism amongst it's taller neighbors, so is State House an odd bird as historian Walter M. Whitehill described it - "a very odd fowl indeed, with a golden topknot, a red breast, white wings and a yellow tail."

Bibliography

Ross, Marjorie Drake. "The book of Boston: The Colonial period, 1630-1775."
Hastings House (January 1, 1960).
Ross, Marjorie Drake. "The book of Boston: The Federal period, 1775 to 1837."
Hastings House (January 1, 1961).
The Bostonian Society. "Old State House History." 2005
URL: http://www.bostonhistory.org/old_state_hs_hist.php
Secretary of the Commonwealth of Massachusetts. "A Tour of the Massachusetts State House." 2006
URL: http://www.sec.state.ma.us/trs/trsbok/trstour.htm
Wikipedia. "Massachusetts State House." April 25, 2006.
URL: http://en.wikipedia.org/wiki/Massachusetts_State_House
Commonwealth of Massachusetts. "Interactive State House." 2006
URL: http://www.mass.gov/statehouse/explore.htm

Buildings of Colonial Boston

Sualeh Fatehi
4/22/2006


The Old State House

Old State House
The Old State House is one of the oldest surviving public buildings in Boston. In its modern setting, it is still pivotal, occupying an island in a traffic junction. This is the site of Boston's first Town House of 1657. The original wooden building burned in the 1711 King Street (State Street) fire, and the interior and some of the brick walls of the rebuilt building burned in the fire of 1747. The new brick building is in typical Georgian style, with the windows in expensive glass panes of 12 over 12. Typically Georgian are the string courses found at intervals for horizontal relief in the building. The British emblems of the Lion and the Unicorn adorn the East face of the building. They were taken down and burned during the revolution, but have since been restored. The East side has a stepped pediment, showing the Dutch influence on British architecture, along with the segmental arch. The architect, however, is unknown. The Old State House building has undergone many architectural and structural changes, including the addition of a subway station in the basement that John Hancock once rented. The earthquake of 1755 dislodged many bricks, and S-ties mark the places where the walls had to be secured.

The balcony of the Old State House has overseen many historic events. Just underneath the balcony is the site of the Boston Massacre in 1770, when British soldiers fired into a crowd, killing five men. Today, a paving stone circle marks this spot. Fugitive slave Crispus Attucks was among the five victims who died that day in the Massacre. Also, in 1776, another historic event took place on the balcony of the Old State House. The Declaration of Independence was first proclaimed from here to an assembled crowd of colonists.


Paul Revere House

Paul Revere House
The Paul Revere House is downtown Boston's oldest building and one of the few remaining from the colonial era. The home was built about 1680 of timber. The main block of the three-story house consisted of four structural bays. There are heavy framing posts and overhead beams. The large fireplaces and absence of hallways are typical of colonial style houses. The L-shaped townhouse contained big rooms and had a second-floor roof overhang and casement windows. A two-story lean-to was added in the L of the house. The original house has a steep roof, but in the mid-eighteenth century, the roofline facing the street was raised substantially to add another floor, and bring the house in line with the Georgian architectural style. The roof has since been restored in the 1907-1908 restoration, and the lean-to removed. Paul Revere and his family of 16 children owned the home from 1770 to 1800, and since then, this house has been called the Paul Revere House.


Old North Church (Christ Church)

Old North Church
The Old North Church is the oldest active church building in Boston, and was built in 1723. The site of Old North Church was a piece of pasture near the top of Copp's Hill, which was the highest elevation in the North End. Timber for the church came from forests around York, Maine, and the bricks were baked in kilns in Medford. The building is designed in the Georgian style. The inspiration comes from the works of Christopher Wren, a British architect who was responsible for rebuilding London after the Great Fire. When a hurricane destroyed the original steeple in 1804, a replacement steeple was designed by Charles Bulfinch. Unfortunately, this steeple too was toppled by a hurricane Carol in 1954. The current steeple uses design elements from the original and the Bulfinch version. At its tip is the original weathervane.


King's Chapel

King's Chapel
King James II ordered an Anglican church to be built in Boston to ensure that the Church of England continued in America. Naturally none of the colonists were interested in selling land for the Church, so the King ordered the Governor to seize a corner of the old burying ground. The burying ground is the final resting place of many colonists, including John Winthrop, the Colony's governor, Hezekiah Usher, the colony's first printer and Mary Chilton, the first woman to step off the Mayflower.

King's Chapel first was a small wooden meeting house at the corner of Tremont and School Streets. This is where the church stands today. Architect Peter Harrison designed the present building and construction began in 1749. The stone building was made of Quincy and Braintree granite. The granite was not quarried, but gun-shotted out from surface beds. A bell made in England was hung in 1772. When it cracked in 1814, a new one, the largest made by Paul Revere was hung in 1816. This bell is still rung before every service. The steeple was left unfinished for lack of funds, and looks incomplete to the present day. The front porch and columns are late Georgian, and added later. They are wooden, but made to look like stone.


Old South Meeting House

Old South Meeting House
The Old South Meeting House was built in 1729 as a Puritan meeting house. This church is famous in that Boston's famous son, Benjamin Franklin was baptized here. The Old South Meeting House was the largest building in Boston, and following the Boston Massacre in 1770, a crowd of several thousand people assembled here to protest against the British troops in town. Samuel Adams persuaded Governor Hutchinson to remove the British troops to Castle William. Another historic event associated with this church is the protest against the tea taxes that led to the Boston Tea Party. In 1773 over 5,000 people crowded into Old South to debate the controversial tea tax. When all attempts at compromise failed, the Sons of Liberty led the way dumping 342 chests of tea into the harbor at Griffin's Wharf. To punish the colonists for the Boston Tea Party, British soldiers ripped out the pews and pulpit and used them for firewood. The church was desecrated, and used as a riding school through the Revolution. In 1783, after sustaining enormous damage, Old South was restored by the congregation as a place of worship.


Old Corner Bookstore

Old Corner Bookstore
The Old Corner Bookstore was built in 1712 as an apothecary shop, office and home of Thomas Crease. It is one of Boston's oldest surviving structures. This building has a gambrel-roof which was typical of the kinds of dwellings and shops that lined the streets of Boston in colonial days. In 1828, after occupation by Brimmer and by Clarke, Carter & Hendee first used the shop as a bookstore. The Old Corner Bookstore really became a famous literary center when the Ticknor and Fields Publishing House was located here from 1832 to 1865. Many famous books were published here, including The Scarlet Letter, Walden, and the Atlantic Monthly magazine. Many famous literary figures such as Ralph Waldo Emerson, Henry Wadsworth Longfellow, Harriet Beecher Stowe, Oliver Wendell Holmes, Louisa May Alcott, Nathaniel Hawthorne, and others brought their manuscripts here to be published. In recent times, the Boston Globe Store founded by The Boston Globe newspaper occupied the building. The present tenant strangely enough is Ultra Diamonds.


Bibliography

Ross, Marjorie Drake. "The book of Boston: The Colonial period, 1630-1775."
Hastings House (January 1, 1960).
Vanderwarker, Peter. "Boston Then and Now: 59 Boston Sites Photographed in the Past and Present"
Dover Publications (September 1, 1982).
The Bostonian Society. "Old State House History." 2005
URL: http://www.bostonhistory.org/old_state_hs_hist.php
The Paul Revere House. "Paul Revere's Home." 2005
URL: http://www.paulreverehouse.org/about/paulreverehouse.shtml
Wikipedia. "Paul Revere House." 12 April 2006
URL: http://en.wikipedia.org/wiki/Paul_Revere_House
Wikipedia. "Old North Church." 4 April 2006
URL: http://en.wikipedia.org/wiki/Paul_Revere_House
The Old North Church. "The Old North Church." 2005
URL: http://www.oldnorth.com/
King's Chapel. "A Brief History Of King's Chapel." 2005
URL: http://www.kings-chapel.org/history.html
CelebrateBoston.com. "King's Chapel & King's Chapel Burying Ground." 2006
URL: http://www.celebrateboston.com/sites/kingschapel.htm
City of Boston. "King's Chapel and King's Chapel Burying Ground." 2006
URL: http://www.cityofboston.gov/freedomtrail/kingschapel.asp
Old South Meeting House. "Old South Meeting House History." 2006
URL: http://www.oldsouthmeetinghouse.org/history/
CelebrateBoston.com. "Old South Meeting House." 2006
URL: http://www.celebrateboston.com/sites/oldsouthchurch.htm
BostonNational Historical Park. "THE FREEDOM TRAIL - Old South Meeting House." 2006
URL: http://www.nps.gov/bost/OSMH.htm
BostonNational Historical Park. "THE FREEDOM TRAIL - Old Corner Bookstore." 2006
URL: http://www.nps.gov/bost/Old_Corner_Bookstore.htm
CelebrateBoston.com. "Old Corner Bookstore Building." 2006
URL:http://www.celebrateboston.com/sites/oldcornerbookstore.htm
City of Boston. "Former site of the Old Corner Bookstore" 2006
URL: http://www.cityofboston.gov/freedomtrail/oldcorner.asp

Monday, May 7, 2012

Virus!

Virus! The very whisper evokes an unreasonable fear. Most people are terrified of viruses: visions of months of work going up in smoke, of lost time, and of lost productivity fill their eyes. The cause? A small program capable of attaching itself to others, and reproducing at will.

The word "virus" means poison in Latin, but a computer virus is called so because of its striking similarity to a biological virus. Biologists have been debating for years whether a virus is living or non-living. It seems to be just some nucleic acid wrapped in an envelope of protein. It is incapable of respiration, doesn't need food, cannot grow, but still has the most important property to claim it to the living: it can reproduce itself. A biological virus attaches itself to the surface of a living cell, and injects its life molecules, its DNA into the host cell. This DNA comandeers the machinery of the cell, and gets the cell to do its bidding. The captured cell then begins to produce viral protein, and viral DNA, and to assemble it into baby viruses.

Similarly, a virus is a computer program that cannot exist on its own. It needs to attach itself to another program, and takes over the working of that program. Once it takes over the working, it can begin to produce copies of itself, which can then infect other programs. In the process, it may make your computer sick, just as a biological virus makes you sick. Computer viruses are transmitted to others just as ordinary viruses. Promiscuous behaviour, like sharing floppy disks is an important cause.
...



© 1994-2012, Sualeh Fatehi. All rights reserved.
This article was written in 1994, and never published.

The Wizard of OS

Imagine five philosophers who have met to dine together. They sit at a round table, with a bowl of noodles in front of each, and a chopstick between the bowls. Every philosopher thinks for a while, and when he gets hungry, picks up a chopstick from one side, if it is free, and then the chopstick from the other side. Only when he is in possession of both chopsticks can he eat. Now, if all the philosophers decide to eat at the same time, and all of them pick up their left chopsticks, none of them can eat - there are no more chopsticks free. They all starve.

That is the famous problem of the dining philosophers - just one of the problems that a multi-tasking operating system has to handle. Some changes have to be made to the allegory of course - the philosophers are running programs, the chopsticks represent the resources required for input or output, and the bowl of noodles the input or output itself.

An operating system is a set of programs that make a computer come alive. A computer is a piece of junk, a mess of semiconductors and wires until an operating system gets to work. The operating system sits in the computer's memory, and co-ordinates all that goes on in the computer. It waits for the user to give a command, and when the command finally comes, understands it, and executes it. It allows the user to load application programs like word processors, spreadsheets, and database systems into the memory, and gets the computer to run them.

At a "lower" level, the operating system provides services to the user's programs. When the word-processor makes a request to open (begin to use) a file, the operating system actually does the work of moving the heads of the disk drive to the correct location, and reading the data from there into special places in memory. It is the operating system that magically turns an inanimate disk drive, consisting of just magnetic platters and heads into a coherent file system. It sets aside some space on the disk for a table where filenames and other information about files, such as the date they were created and their size, can be stored. Then it provides the means of accessing information stored in the files, by furnishing services to open, close, read from and write to files, for example.

The operating system also takes charge of all the input and output devices connected to a computer, like the keyboard, terminal screen, printer and disk drives, and co-ordinates their activities. This not an easy job - what is the use of a computer that, for example, if when it is busy printing something loses what the user types on his keyboard. When anything important like the pressing of a key occurs, it is often the operating system that makes the computer suspend the calculations that it was performing, and attend to the cause of the alarm. A modern computer is capable of switching back and forth quickly from one job to another. Very often, we use application programs that display a clock in one corner of the screen, which changes its time every second, without affecting what we do; we don't realise that every second the computer's attention has left us to attend to the clock.

At a "higher" level, an operating system typically provides a "shell" where the user can enter commands. (The part of the operating system that provides the basic organisation of the hardware, and the services is called the "kernel".) The shell understands many commands, for example a command to list all the files on a disk - such a command is "dir" on MS-DOS, and "ls" on Unix. Other commands include those to copy a file, to delete it from the disk, and so on. Since the user interacts with the shell (which in turn interacts with the kernel, which uses the underlying hardware), and users are now increasingly novices, the shell is the subject of improvement. Newer operating systems, like Windows-NT and the Macintosh operating system present a graphical user interface (GUI - programmers say "gooey": that's what they think of it) to the user. The user sees a lovely multicoloured screen, and gets his or her work done using a mouse, by moving to pictures (called icons), and clicking mouse buttons. There is no need to remember and to type any command at all.

The development of operating systems naturally enough parallels the development of computers. In the earliest computers, where miles of magnetic tape had to be loaded and unloaded manually, the computer idled for a lot of time. Therefore a "batch operating system" was invented, where a series of operations could be specified at one time, in a batch, at executed one after the other, quickly. With faster disk drives coming into the picture, multi-programming was tried out. This means running several programs at the same time, and arises out a simple fact. However fast we try to make disks drives, they are still not able to match the computing speeds of a computer - still, programs need disks to store their large amounts of data permanently. So, when a program is either reading or writing data, the disks may be working hard, but the computer itself is idle. At this time the multi-programming operating system comes in and switches the computer's attention to another program that is at a calculations stage. Thus, a multi-programming system makes efficient use of an entire computer installation.

Computers are getting still faster, and their users more demanding. Clearly, a multi-programming system with say fifty users typing letters would not work: each user would get attended to once in a long time. For letter writing and other interactive applications, the computer has to respond fast, or what you have typed at the keyboard will take centuries to come on the screen. For such people, we have "time sharing" systems, where the computer switches from one person to another every hundredth of a second or so (an average typist can type thirty words in a second). We have to make sure that the epistolers are happy, and that the philosophers don't starve.


© 1994-2012, Sualeh Fatehi. All rights reserved.
This article was written in 1994, and published in Express Computer, India's leading national computer weekly, in October 1997.

The World in a Brain

Will computers ever take over the world? Human beings are still superior to computers. A computer may be a fast and accurate calculating machine, but human beings are capable of taking complex decisions quickly, and learning from past experiences.

Take a game of chess. At a stage somewhere in the middle of the game, there may be scores of possible moves. And then, to be a successful player, one has to think in advance. Do you really think that chess grandmasters go through all the moves, and all future positions in their minds? Then again, how does a child acquire language? Learning and past experience are used to their fullest extent in skill acquisition.

On the other hand, a chess-playing computer might have to go though all possible moves, attaching points to each piece, and finding the best move numerically. Of course it will do this very fast, and in addition may have a complicated program that finds out in advance which moves are worth examining. Also, it may "learn" from the games of grandmasters. On the other hand, the learning we are talking about is learning from scratch. It would be a very wise computer that could learn the rules of chess from watching a few games. A child learns language in the same way, with a few corrections from its parents.

Recognising the superiority of the human brain, researchers have examined in detail, and are still finding out more about it. The brain consists of thousands of millions of neurons, heavily interconnected with one another. Each neuron consists of a cell body, from which emerges a single axon. At the end of the axon are a multitude of branches that just about touch other neurons. The cell body looks hairy under a microscope because of hundreds of dendrites, the fibres that are connected to the branches of another neuron's axon. It is sheer numbers - millions upon millions of neurons connected to hundreds of neighbours that makes human brains (and other animal brains) the complicated machines that they are. A nervous signal received at the cell body is transmitted down the axon, and to all the other cells making connections with it. This transmission doesn't happen at random, but works on the "all or none" principle. That is, if all the excitatory signals coming through the dendrites reach or exceed a certain threshold value, the axon fires. Now each connection at the dendrite, called a synapse, has a weightage. Weightages may even be negative, or inhibitory. So if a certain neuron fires at a threshold signal of 1, and the weightages of the incoming signals are 0.2, 0.3, 0.6 and -0.1, the axon will fire. Summation of signals may also be over a period of time: small impulses coming repeatedly will also cause an axon to fire.

So what is interesting about these facts? It is that these weightages are not fixed at birth, but change throughout life by a process known as facilitation. Anything new that is learned, or any new response to old stimuli is a result of the dynamic changes at the synapses. In fact, in infants, the learning process results in the creation of new synaptic connections. Therefore, it is important that children are exposed to colours, noises, tastes, smells and interesting textures to touch. This is what causes the brain to "grow". An early experiment on kittens kept in the dark for the first few weeks of their life showed that they turned out blind, because neural connections were simply not formed in the absence of stimuli.

After knowing all this, the next question is - can we duplicate this? No, you may say. But that is similar to the disbelief that the German chemist Frederich Wohler faced when he synthesised urea in his laboratory in 1824. Before Wohler, it was thought that all "organic" chemicals were produced by a life force, and were therefore special. Today, we think nothing of the millions of organic chemicals that we use in daily life: our enzyme detergents, our synthetic fabrics, our plastic buckets. If we can make a "brain", the possibilities are enormous: everything that conventional computers find difficult to do can be attempted. For example, speech recognition, signature verification, speech synthesis, teaching - human things.

The answer is that it has been done. As early as 1958, Frank Rosenblatt was working on the Perceptron. This machine actually learned from experience, using Hebb's rule, reinforcing connections. In Bell Labs, Larry Jackel and team put together 75,000 transistors, 54 simple processors connected by resistors, creating 14,000 artificial neurons with light sensitive amorphous silicon. A picture projected on this screen repeatedly was learnt, and then the circuits could reconstruct the whole if only a part was shown.

There are more amazing neural networks still. The Wizard at Brunell University can analyse TV images of human faces. It can really tell you whether they are smiling or frowning - get any supercomputer to do that! Most neural nets have to be taught, by a teacher who knows all the answers. This is known as supervised learning, as opposed to unsupervised learning, where the net just "picks up" things on its own. Supervised learning may be reinforcement learning, like a child is taught, where the neural net is told how well it performed, so that the weights of input can be adjusted. Fully supervised learning is when the teacher takes the trouble to inform the neural net what the correct response would have been. ALVINN (Autonomous Land Vehicle Neural Network) drives a NAVLAB vehicle through the Carnegie Mellon University campus. It has to be taught first, with 1200 simulated images, shown 40 times each; it takes 30 minutes to learn. After that, it can manoeuvre the vehicle at 3.5 miles per hour - which is twice as fast as a conventional computer could do it.

Well, are we close to an electronic brain? What would you say? Your guess is as good as mine. Present neural networks are slow - half as slow as a housefly, which doesn't even have a brain, only knots of neurons known as ganglia. It will take a lot of evolution to reach the capacity of the human brain, and our generation will await it with mixed feelings.


© 1994-2012, Sualeh Fatehi. All rights reserved.
This article was written in 1994, and published in Express Computer, India's leading national computer weekly, in October 1997.

What's in a Name?

Man has been discovering metals right from prehistoric times and will continue to complete the far from finished list of trans-uranic metals. All but 22 elements can be considered metals and the names for these various metals are drawn from the vast gamut of human activity.

Patriotic discoverers have turned to their homelands, or cities for inspiration, others have drawn from mythological figures. Great scientists are honoured by having metals named after them. Some discoverers, apparently fascinated by the vast stillness of space, have named their discoveries after heavenly bodies.
The Rhine provinces of Germany,
and the river after which
rhenium was named.


Amongst these, were the discoverers of scandium, for Scandinavia; rhenium named for the Rhine provinces of Germany; europium, for Europe; and thulium, for Thule, or the Northland. Marie Curie named her second discovery polonium, after her much loved motherland, Poland. There are two metals named after France - francium and gallium (Gallia is the Latin for France). Although gallium is named after France, jealous dissenters at the time of its discovery in 1875, said that it was a cleverly concealed ploy on the part of its discoverer to name it after himself. The discoverer, Lecoq de Boisbaudran's name, 'Le-coq' means 'the Cock', and the Latin for cock is gallus.
The Eiffel Tower, a landmark of Paris,
the city after which
lutetium is named.

Some other metals are named after cities. For example magnesium is named after Magnesia, an ancient city in Asia Minor; hafnium from the Latin name of Copenhagen; holmium, from Holmia, Latin for Stockholm; and lutetium, from the Latin for Paris, Lutetia. Strontium gets its name from Strontian, a small village in Scotland. In 1787, a rare mineral was unearthed there. This mineral contained the 'earth' (oxide) of the element. Soon, the British chemist, Hope, got interested in the mineral, and isolated it in 1792. The village of Ytterby in Sweden has given its name to no less than four elements - yttrium, ytterbium, terbium and erbium. Not a single continent, state, or city has been awarded such an honour.

The salts that metals form are of various colours. In fact, these colours have been the basis for the naming of many metals. Chromium forms varicoloured salts, and gets its name from chroma, or colour. Iridium, forming rainbow-coloured salts gets its name from iris, the rainbow. Praseodymium characteristically forms green salts and gets its name from prasios didymos, or green twin. Rhodium's salts in solution look rosy and so it is named rhodon, or rose-coloured. Metals can be identified by the colour they impart to flame. For example potassium gives a subtle lilac flame, sodium gives fiery golden-yellow, and copper a soft apple green. Rubidium imparts a red colour to the flame and so is named from the Latin for red, rubidus. Similarly, caesium makes the flame sky-blue and is named after the sky-blue colour, caesius. Thallium has a spring green spectral line and was fittingly discovered in spring. It was named for the budding twig, thallos. Indigo, India's famed dark blue dye, gave its name to indium, whose spectrum consists of a bright blue line.

The rape of Proserpine (or Persephone)
as sculpted by Gian Lorenzo Bernini (1622),
 immortalises the Greek god of the underworld
- Pluto.
Still another set of metals is named after mythological figures. The Scandinavian goddess, Vanadis has lent her name to vanadium and the blustering Scandinavian war god, Thor, to thorium. The transition metals tantalum and niobium are usually found in close alliance and so it is fitting that one should be named after King Tantalum of Greek mythology and the other after his daughter, Princess Niobe. (In fact the name of element number 41 was changed from columbium to conform to this pattern). The strong metal, titanium, was named after the Titans, the supermen of Greek mythology. Promethium is named after Prometheus, the daring youth who stole fire from the gods. The poisonous ores of cobalt were once dangerous to mine and therefore cobalt gets its name from the German for evil spirit, Kobald.
Enrico Fermi, the scientist
who inspired the name fermium.

Many newly discovered elements have been named to commemorate great scientists of the past. Fermium reminds us of Enrico Fermi, einsteinium of Albert Einstein, nobelium of Alfred Nobel and curium of the backbreaking labours of Marie and Pierre Curie. Lawrencium is reminiscent of Ernest O. Lawrence.

Other metals like samarium and gadolinium are indirectly named after people. The Russian mine official, Colonel V.E. Samarsky gave his name to the mineral samarite from which samarium was mined and the Finnish chemist Professor Gadolino of Turku University gave his name to gadolinite, from which gadolinium was found.

There are some elements that are named after heavenly bodies. They can be said to be named after mythological figures which most heavenly bodies are named after. For example, palladium was named after the asteroid Pallas, cerium after the planetoid Ceres. Uranium (number 92) was named after the planet Uranus. Element number 93 was named neptunium, after the planet Neptune, the planet beyond Uranus, and number 94, plutonium after Pluto, beyond Neptune.

Metals that are inactive and occur in their native forms have been known since prehistoric times. Their names have passed down the ages unchanged (lead and tin are Old English words), or with minor variations and corruptions - as iron for iren, silver for seolfor. Geolo is the common etymological root for gold and yellow. Other newly discovered metals took on the names of older ones. Molybdenum was discovered from what was thought to be lead ore and so its name is derived from molybdos or lead. Similarly it was thought that a reddish ore would yield copper instead it yielded nickel. Nickel is the contraction of kupfernickel, or 'false copper'. Platinium because it so resembles silver was named after platina, or 'little silver'.



The names of elements through 118 have recently been accepted by nuclear scientists and certified by the International Union of Pure and Applied Chemistry. This completes the last row of the periodic table.

Most of the newer super-heavy elements are named after famous scientists. Rutherfordium is named after Ernest R. Rutherford, the New Zealand physicist; it was formerly called kurchatovium by the Russians, after Vasilevich Kurchatov, the late Head of Soviet Nuclear Research. Seaborgium is named after Glenn T. Seaborg, American nuclear chemist and Nobel Prize winner. Bohrium is named after Niels Bohr, the Danish physicist, and meitnerium after Lise Meitner, the Austrian physicist. Roentgenium is named after the German discoverer of X-rays, Wilhelm Conrad Röntgen, and copernicium after astronomer Nicolaus Copernicus. Oganesson is named for professor Yuri Oganessian, a pioneer in the discovery of superheavy elements.

Some are named after the laboratories where they were synthesized. Livermorium is named after the Lawrence Livermore National Laboratory in Livermore, California, and flerovium after the Flerov Laboratory of Nuclear Reactions. By extension, flerovium is named after Georgiy N. Flerov, discoverer of the spontaneous fission of uranium. Darmstadtium is named after the Institute for Heavy Ion Research in Darmstadt, Germany. Hassium was synthesized in the same institute, and is named after the German state of Hesse (where the city of Darmstadt is located), from the Latin Hassias.

New elements continue to be named after places. Moscovium and dubnium, both discovered at the Joint Institute for Nuclear Research in Dubna, Russia, are named after the city and province of their discovery. Researchers at three laboratories in Tennessee, the Oak Ridge National Laboratory, Vanderbilt University and the University of Tennessee at Knoxville worked together to discover tennessine, which is named after the state. Japan gives its name to nihonium, and it is the first element to be discovered in an Asian country. "Nihon" means "Land of Rising Sun".


© 1985-2016, Sualeh Fatehi. All rights reserved.
This article was written in 1985, and published in Science Today, India's leading popular science magazine, in July 1985.

BIS – As I see it in 2000 A.D.

I had come to visit my dear old school. It was 2000 A.D. - nearly 2 decades after I had passed out. I was thrilled to see my alma mater after so long, on my visit to Bombay. It was nothing like I remembered it - 4 stories rising skyward, the corridors thronged with noisy children, our classroom, and teachers! They didn't have teachers now. With the population cut so drastically, they couldn't afford to waste manpower on such an unimportant task as teaching children.

Today children were taught by cyborgs - the marvelous combination of a human embryo brain, programmed to teach a subject. It had its terminals on the desks of the children-video screens and a sort of typewriter. The pens we used to use have long since become old-fashioned. The children of the ninth standard were being taught the elementary rules of telepathy – the art of transferring thoughts. Our school still maintained its small population.

The school was built under a beautiful garden, tended by the children. It went 9 stories underground. This new structural form of building was very versatile and stable. It was resistant to fires and earthquakes. The concrete structure had a new compound that would not catch fire, and the buildings being underground prevented it toppling over like matchsticks, as did the skyscrapers of old. The only buildings above ground were administrative ones, but they too were protected by a very elastic layer of concrete at their bases.

In the recess, the children crowded around me, eager to know how their school looked ages before they were born. After answering some sensible queries, I found a path through them, and found the way to the games grounds, after taking directions from a cyborg robot discipliner. The grounds were large rooms, filled with synthetic soil, and marked for different games. There was hockcricket, a game played with a curved stick and stumps. I didn't enjoy descriptions of the games, for they were all sorts of terrible mixtures of games played in my time.

I went to see the Principal, which was a sort of triumvirate, because it held 3 brains in a common fluid. Their blood vessels were linked. Whenever an important decision was to be reached, the brains held an internal conference, and relayed their answer through electronic means to cyborg robots, who executed it. I somehow pity the 100 human brains in isolation in the school, and thank my lucky stars that l was chosen to have a body. The children prefer their cyborg teachers to complete robots. They have human feelings and human failings.

Before leaving, I just peeped into the students’ hostel. The students’ cabins were spick and span, having just been cleaned by electronic vacuum cleaners. The students were allowed to decorate their own rooms as they pleased. After this enjoyable and exciting day, I went to the school parking ground, got into my vacuum car.

After going through the air locks, I got into vacuum local 23. It was nice to be sucked along by the power of vacuum. After some time, I turned into vacuum highway 4, and settled down to a long ride, after switching the oxygenizer to high.


25 years later, I have the opportunity to visit my old school again. I laugh when I remember the English essay on BIS that I had written 25 years ago, which had been read out in class, and printed in the school magazine. The school is unchanged through the years. The playground is as dusty, with the same red mud, and the same kids playing football. We have acquired more flats in the building, it is freshly painted, and there is work going on to create a new section. None of the old teachers are there any more, but I do meet some contemporaries who have their own kids in school. Our favorite skeleton and formaldehyded specimens still adorn the biology lab. The principal is Mrs Seervai now, and not a feared triumvirate of brains. I proceed up to lunch with the children, and everything is as remembered, except that I sit with the teachers this time. It has been a fun visit, and I hope that not another 25 years pass before I visit again.


© 1984-2012, Sualeh Fatehi. All rights reserved.
This article was written in 1984, and published in the BIS school yearbook, Spectrum, in 1984.