This post is copied from: ArchLinux: Users and groups
/etc/group is the file that defines the groups on the system.
Display group membership with the
]$ groups [user]
user is omitted, the current user’s group names are displayed.
id command provides additional detail, such as the user’s UID and associated GIDs:
]$ id [user]
To list all groups on the system:
]$ cat /etc/group
Create new groups with the
]# groupadd [group]
Add users to a group with the
]# gpasswd -a [user] [group]
Modify an existing group with
groupmod; e.g. to rename
old_group group to
new_group whilst preserving gid (all files previously owned by
old_group will be owned by
]# groupmod -n [old_group] [new_group]
To delete existing groups:
]# groupdel [group]
To remove users from a group:
]# gpasswd -d [user] [group]
If the user is currently logged in, he/she must log out and in again for the change to have effect.
To list users currently logged on the system, the
who command can be used.
To add a new user, use the
# useradd -m -g [initial_group] -G [additional_groups] -s [login_shell] [username]
-mcreates the user home directory as
/home/username. Within their home directory, a non-root user can write files, delete them, install programs, and so on.
-gdefines the group name or number of the user’s initial login group. If specified, the group name must exist; if a group number is provided, it must refer to an already existing group. If not specified, the behaviour of useradd will depend on the
USERGROUPS_ENABvariable contained in
/etc/login.defs. The default behaviour (
USERGROUPS_ENAB yes) is to create a group with the same name as the username, with
-Gintroduces a list of supplementary groups which the user is also a member of. Each group is separated from the next by a comma, with no intervening spaces. The default is for the user to belong only to the initial group.
-sdefines the path and file name of the user’s default login shell. After the boot process is complete, the default login shell is the one specified here. Ensure the chosen shell package is installed if choosing something other thanBash.
/etc/shells. For programs that use PAM, this is checked by the
Example adding a user
On a typical desktop system, use the following command to add a new user named
archie, specify Bash as their login shell and add them to the
wheel group (see the entry in #User groups for details):
# useradd -m -G wheel -s /bin/bash archie
This command will also automatically create a group called
archie with the same GID as the UID of the user
archie and makes this the default group for
archie on login. Making each user have their own group (with group name same as user name and GID same as UID) is the preferred way to add users.
You could also make the default group something else, e.g.
# useradd -m -g users -G wheel -s /bin/bash archie
However, this is not recommended for multi-user systems. Typically, the method for facilitating shared write access for specific groups of users while keeping home directories private is setting user umask value to
002, meaning the default group (
users in the example above) will by default always have write access to any file you create. The user’s home folder, which is owned by a group with group name same as user name, will be read-only for other system users, while shared files/folders can be made writeable by default for everyone in the operative group. The owning group can be automatically fixed to the group which owns the parent directory by setting the group sticky bit on this directory:
# chmod g+s our_shared_directory
Otherwise the file creator’s default group (usually the same as the user name) is used.
Other examples of user management
To add a user to other groups use:
# usermod -aG additional_groups username
Alternatively, gpasswd may be used. Though the username can only be added (or removed) from one group at a time.
# gpasswd --add username group
-aoption is omitted in the usermod command above, the user is removed from all groups not listed in
additional_groups(i.e. the user will be member only of those groups listed in
To enter user information for the GECOS field (e.g. the full user name), type:
# chfn username
(this way chfn runs in interactive mode).
To specify the user’s password, type:
# passwd username
To mark a user’s password as expired, requiring them to create a new password the first time they log in, type:
# chage -d 0 username
User accounts may be deleted with the userdel command.
# userdel -r username
-r option specifies that the user’s home directory and mail spool should also be deleted.


Tuesday, August 9, 2011
In 1889, at the order of the United States Post Office Department, the American Bank Note Co. prepared special printings of a range of earlier Bank Note issues that had been produced between 1879 and 1888. Copies of U.S. stamps issued since 1851 that were subsequently circulated for official, promotional, or educational purposes had been overprinted "Specimen." This special printing had never been intended for postal use of any kind; however, it apparently was felt that a "Specimen" overprint was inappropriate for use on these stamps. To ensure that they would not be confused with regular stamps and postally used, therefore, these stamps were given "SAMPLE" and "SAMPLE A" overprints in red or blue. (On four of them, all or part of the overprint appears in manuscript.) The stamps are listed with specimen stamps in the Scott Specialized Catalogue of United States Stamps & Covers.
A roulette that leaves angular, pointed edges.
Any non-postal labels used to raise money for charity or to decorate or seal envelopes.
A full roll of coil stamps that is in the original condition it was when sold at the post office. The size of the roll and characteristics can differ, but it will bear some form of seal, label, or wrapper. Some collectors save full, sealed coil rolls, and others purchase them to break down into desirable components. Sealed coils can be found from virtually every country that has produced coil stamps. With rare exceptions, most sealed coil rolls do not command premiums over the prices of their component stamps.
United States revenue stamps released in 1871 to replace the first issue series. The second issue stamps differ slightly in design from first issue examples and were printed on chameleon paper with silk fibers. This was intended to prevent unlawful cleaning of the cancels and subsequent illegal reuse.
Tiny marks on stamps added by the artist or engraver to allow two similar designs to be told apart. These are frequently used with specific reference to early U.S. 19th century bank not issues. Some engravers also hide heir names or other details in stamp designs, only to be discovered later by sharp-eyed collectors. These, too, are known as secret marks.
A catchall term that refers to different types of paper, including silk, chalky, and prephosphored papers, among others, used to prevent counterfeiting of stamps.
Selective Block Tagging
Although similar to block tagging, this type of application involves the cutting of tagging rollers on a pantograph machine to leave untagged areas on printed stamps. Examples of this type of tagging include the 1988 Classic Autos booklet and the 13-cent Eagle and Shield definitive. The untagged area left by selective block tagging allows the cancellation ink to adequately permeate the stamp paper to prevent illegal reuse.
Stamps with pressure-sensitive adhesive. Stamps with self-adhesive gum require no moisture to apply. They feature a sheet of silicone-coated backing paper beneath that keeps them intact until they are used. The first self-adhesive U.S. stamp, a pre-canceled die-cut 10-cent Dove Weathervane introduced for use on Christmas cards in October 1974, met with only modest success, and the gum has tended to produce mottled brown spots on mint copies. Improved self-adhesive stamps issued during the last decade, however, beginning with the 1989 25-cent Eagle and Shield, have become popular with postal patrons. Self-adhesive technology is relatively new to stamps, but currently accounts for the vast majority of new postage stamps produced in the United States. The first self-adhesive stamp was released by Sierra Leone in 1964 to salute the New York World's Fair.
The unprinted paper surrounding the stamp in a pane, sheet, or booklet. The term also refers to the paper that borders sheets and pans of stamps as they are printed.
Example of "Selvage" that borders a small sheet of stamps
A postage stamp that also serves as a receipt for the prepayment of an additional fee, usually to benefit charity. This additional fee frequently is represented in the stamp's denomination as a "plus" indicator. Thus, a stamp with 3+2c denomination denotes 3 cents postage and 2 cents to a specific charity.
See Perforations and Roulette.
A grouping of stamps by design, theme, or other means, intentionally released as a group over a period of months or years.
A form of roulette consisting of wavy lines.
Serrated roulette (or Saw Tooth Rouletting)
A form of rouletting, probably in which the simulated perforations fit together in an interlocking pattern of jagged right angles.
When overprinted on a stamp, the term generally means "on government service." The overprint indicates the stamp is valid for use only by a governmental official.
Stamps containing text indicating their intended function or rate, either as an integral part of the stamp design (as in the "BULK RATE" inscription on the 7.9-cent Drum definitive) or applied as an overprint (as in "CAR-RT SORT" Bureau pre-cancel.
Stamps released to mark the 150th anniversary of a significant date or event.
A grouping of stamps all belonging to the same issue or series.
Often inaccurately referred to as offset, set-off is a phenomenon that occurs when freshly printed sheets of stamps are stacked before the ink has completely dried. The design from a bottom sheet frequently, partially or fully, transfers to the un printed side of the sheet directly above it. The more complete the impression, the more desirable the freak is to collectors. The most pronounced examples of set offs are caused by a printing plate leaving a fully inked impression on an underlying roller when the press skips a sheet of paper. Subsequent sheets then receive normally inked impressions on the top side, as well as a reversed impression on the gummed side, where it has come in contact with the roller. Subsequent offset impressions fade as the ink on the roller is exhausted. These freaks, which are usually strong impressions, are greatly sought after. A third form of set off can be simulated by normally printed stamps sticking together as a result of high humidity. When pulled apart, they can give the appearance of an offset, but they are not true set offs and have no philatelic value. Another similar form of setoff can also occur through improper storage of stamps in albums. Under pressure, stamp designs transfer from the face of the stamp to the next album page. This form of setoff is not desirable.
Two or more stamps of different designs or types that are attached. Se-tenant issues have become more popular in recent years with a number of different countries. Unintentional se-tenants also exist. If different die types or major variations occur on different stamps from the same sheet or pane, a pair of stamps exhibiting these different characteristics are considered to be se-tenant.
Sewing Machine Perfs
Privately produced perforations on imperforate second issue revenues. It is believed that the buyer of what would have been imperforate errors ran the stamps through a sewing machine, letting the needle to the perforating.
A color variation from the normally released version. A shade by nature refers only to one particular mix of hue and chroma, but is compared by collectors to what is considered normal for a stamp.
A complete printing sheet of stamps as it comes off the press. It may well be sliced into post office panes at a later date.
An oversized glassine envelope capable of holding an entire mint pane.
A flat-plate press that prints stamps in individual sheets, as opposed to a webfed rotary press, which utilizes large rolls, or webs, of paper.
A postal marking applied aboard a ship. Such markings usually give not only the date, but also the name of the ship and, occasionally, the shipping line name. Such cancels are usually considered desirable.
Poor separation of attached stamps may result in one perforation tooth that is shorter than its neighbors. While a short perf is considered a fault, it may not seriously affect a stamp's value negatively. Short Set A grouping of stamps from the same issue or series that may be missing one or two values, usually the high values in the packet trade.
The practice (or art) of creating printing plates from the original die by using transfer rolls to rock stamp images onto the printing plate. Most siderography is now done by machine, rather than by hand.
Revenue stamp paper that includes silk fibers. (The early experimental silk paper, found on first issue revenues and some private die proprietaries is difficult to distinguish.) In many cases, only a single fiber or two may be found on one stamp. Later silk paper types have numerous, highly visible silk fibers appearing in the paper.
Silver Tax Stamps
Used to pay tax on the net profit on the sale of silver bullion (1934-63). Silver tax stamps were to be affixed to the transfer memorandum. Although the last silver tax stamps were released in 1944, their use was continued until June 4, 1963.
Stamps that have been postally used but were not canceled. Although the use of skips is illegal, many people view them as found money. Once removed from the envelope, there is no way to distinguish a skip from an unused stamp without gum.
Abbreviation for straight line, referring, for example, to a town marking consisting of a straight line.
A stamp that is in short supply or inherently desirable for some reason, but the value has not yet been discovered by collectors.
Metal die hub cancels that bear some informational, advertising, promotional, or propaganda message. They are found on the covers of many countries. Slogan cancels may also be hand-stamped, but do not occur as frequently as machine cancels.
Smears, Blobs, and Blotches
Caused on stamps by excess ink, by cleaning solvent or other chemicals, on the printing plate at some point during production.
A perforation anomaly that appears on some stamps of the 1990s processed on what is known as an APS grinding perforator. The name comes from the appearance of the anomaly: stacked perforation holes that resemble a sideways snowman. The APS grinding perforator does not punch holes in the stamp paper; it grinds out the holes, with the use of three rotary blades and a perforation pattern die that pushes the paper into cutting blades, producing dust, rather than tiny circles of paper. The practice, known as skiving, was borrowed from the leather making industry, where thin layers of skin are removed from the hide. Cutting heads are positioned so that the web first travels pas one cutter, grinding away the paper and perforating that portion of the web first. The web then travels under a take-up roller to the remaining two cutting heads. If the paper slips slightly out of alignment, or if the take-up rolls develop play or chatter, the edges of the blades, which normally overlap two or three holes, double-cut the stamps out of alignment, causing the snowman affect of slightly doubled perforations.
The process of removing stamps from their envelope backings by immersing in cool water for a time. Soaked stamps are then placed face down on absorbent paper to dry.
See Bull's Eye.
The most dramatic form of color smear, these result from use of solvents to clean printing plates. After cleaning, solvent remainders thin printing ink to the point that t messily smears across the surface of the finished stamp. Like all freaks, these items are supposed to be cut from the printed web of stamp paper and destroyed, but they occasionally slip though, to the delight of collectors.
Special items with philatelic interest, usually released in conjunction with philatelic exhibitions. Souvenir cards may or may not depict stamps. In some cases, such as those produced by the Bureau of Engraving and printing, souvenir cards bear die imprints of actual postage stamps. Souvenir cards are not valid for postage, but are simply intended to be attractive souvenirs.
A specific product of the United States Postal Service. A souvenir panel is a specially engraved card, with text relating to a stamp issue. A mint block of four stamps is then added to the panel and sold as a souvenir.
Typically a small pane or sheet that contains one or more stamps, released for a specific event or purpose. The margins of souvenir sheets frequently are very large and contain printed information describing the stamps, the purpose of issue, or the special event being commemorated. The stamps in a souvenir sheet may either be perforated or imperforate, and, with rare exceptions, are valid for postage, either as part of the sheet or cut out and affixed separately. In many cases, stamps in souvenir sheets reproduce older stamp issues. Souvenir sheets have been issued by most countries at one time or another, frequently in celebration of a large stamp show.
Example of a "Souvenir Sheet"
A damaged or inferior copy of a stamp valued chiefly for its ability to fill as spot in an album. It is assumed that the stamp will be replaced when a better example is obtained, unless it happens to be very rare or valuable.
The corner area between the vignette (or central oval) and the outer frame line or border. This corner area frequently includes decorative design elements.
A special service of mail used when a sender wishes a communication to be delivered quickly, by messenger, upon its arrival at the post office. Many different countries have released special delivery stamps for this service. In recent years, special delivery has fallen out of favor with mailers (and was discontinued in the United States in 1997). Expedited services, such as Express Mail, have largely replaced the need for special delivery.
Stamps representing a special fee for a service used on fourth-class mail that gives it the same handling privileges as first-class mail.
Stamps created for distribution to dignitaries as special favors, or for sale (often long after the fact) to collectors. They may or may not be valid for postage. Such stamps also may or may not be produced from original printing plates. Examples of special printings include the 1875 printings of numerous U.S. stamps (including newly engraved reproductions of numbers 1 and 2). The exact line of what constitutes a special printing is not always clear. The so-called Farley's Follies issues of the 1930's, which were produced to make stamps given to dignitaries available to collectors, are considered by most to be special printings. The intentional printing of the 1962 Hamarskjold Invert is, in fact, a special printing, but is not generally acknowledged as such.
There is some discussion among collectors over special stamps, a not-entirely-satisfactory term coined by the U.S. Postal Service. These stamps fall somewhere between definitives and commemoratives in both size and use. They may be reprinted from time to time, like definitives, but are issued in a very limited range of denominations and have a more specialized function or intended period of use than ordinary definitives do. The Christmas stamps issued since 1962 and the Love stamps issued since 1973 are examples of U.S. special issues.
A collector who studies and gains special knowledge in one particular area. This can include country or topical collections as well as specialized studies of a single stamp or series. In many cases, the dedicated specialist is able to serve as an expert in his or her chosen specialty.
A stamp that has been defaced by means of an overprint, perforation pattern, or other obliterations for the purpose of creating samples to be given to postmasters, philatelic agencies, and others.


Richmond Gaol is the oldest intact gaol in Australia, located just a 20-minute drive north-east of Hobart.
The Gaol was built in 1825 and is one of the best preserved convict structures still existing in Tasmania. You can step inside a solitary confinement cell measuring just one by two metres (6x3 feet).
One of the Gaol's most infamous inmates was English convict, Ikey Solomon, said to be the model for Charles Dicken's character Fagin in Oliver Twist.
Below and included in photos are chain-gang sleeping rooms, the flogging yards, the cook house and holding rooms, all with historical relics and documents to bring the convict past to life.
Your Mattress and Pillow
Richmond Gaol is the oldest, still intact, gaol in Australia. It predates the penal colony at Port Arthur by five years. A cornerstone of the convict system devised by Governor Arthur, the gaol was erected by convicts in 1825-27 in several stages. The 1835 wing built to accommodate women prisoners are the best preserved female convict structures still existing in Tasmania. Specific regulations drafted for the Richmond Gaol in the 1830s aimed to maintain a constant vigil on the prisoners. Floggings - usually carried out by convicts or ex-convicts themselves - were frequent. The colonial hangman, Solomon Bleay, was also imprisoned at Richmond Gaol, being escorted to and from Hobart and Launceston (the only places of execution), when necessary, to carry out his duties. Many of the gaol’s prisoners remained unbowed by the system imposed upon them and escapes were frequent throughout its history. Convicts resorted to all manner of means to break out, including removing roof shingles, digging under the foundations and removing lintels over windows. In 1945 the gaol was ceded to the State Government as a State Reserve under the Scenery Preservation Board and subsequently gazetted as an Historic Site under the National Parks and Wildlife Act in 1970.
Hold Hands and Smile
Our visit was filled with history at each turn here the place has a strange feel, and as you walk into the tiny cells you van feel the pain that some must have felt and the PA system from which sounds of people in pain are heard and chains being rattled by ghostly figures. Just to walk in the for steps of those poor people is a strange feeling, its a place you would not wish to be in at anytime while it was a working goal, the guards would have been a cruel bunch, Well worth the $10 dollars each to have a look


The first month of the Cartographer's Annual is the Mercator style pack. It tries to capture the flair and style of 16th and 17th century maps. Those centuries - the so-called "Age of Exploration" - were an era of immense European exploration and expansion and the art of cartography flourished to document and publish the newly discovered information on the shape of the world.
For a time the principal center of map making and map printing was in the Netherlands. Gerard Mercator is the most famous of those cartographers and therefore this map style is named in his honor. The Flemish mathematician, printer and mapmaker (born 1512, died 1592) compiled the first modern world atlas (titled "Theatrum Orbis Terrarum") and invented the map projection that still bears his name today.
The style pack Mercator includes


~300 kya The line that will become AMH (anatomically modern humans) diverges from archaic humans
200 kya - 100 kya AMH fixes on one y chromosome and one mitochondia.
~ 100 kya AMH moves out of its isolated home into surrounding areas, most notably South Africa and the Levant
~ 75 kya The Toba super eruption eliminates archaic human populations from South Asia (but not Africa or Europe)
74 kya - 60 kya AMH populate all of South Asia
~ 60 kya and 16 kya AMH develop agriculture (perhaps a reinvention) and slowly construct a vast neolithic civilization on the Indian subcontinent
16 kya after warming for 4 ky, the Older Dryas throws Earth back into a 500 year mini ice age. It is harmless to the South Asia civilization, but it likely stresses much of the archaic human population elsewhere.
14.7 kya - 13.5 kya Meltwater Pulse 1 A floods coastal cities in South Asia
13.0 kya - 11.3 kya The Younger Dryas throws the world back into the Ice Age, which in combination with continued rapid increases in sea level, destroys the South Asia civilization and creates waves of refugees in all directions.
12.8 kya The Age of Leo begins. Egyptian Sphinx built around 12.4 kya to signify to refugees that survivors are living in what, today, is the Eastern Sahara.
~ 11 kya Refugees in Asia Minor, Turkey, etc. begin rebuilding rudimentary settlements and agriculture.
~ 6 kya agriculturally based civilizations begin forming throughout Asia and Northern Central Asia and Eastern Europe. The Sahara turns into a desert and a culture forms in Egypt along the Nile.
The rest, quite literally, is history. The real question here is that period of 44 ky from 60 kya and 16 kya. It is profoundly puzzling how the period after the ~4ky of climatological disruption could be characterized by the emergence of agriculture and civilization all over the full extent of human range, but for 44 ky the indian subcontinent, whith human populations and a broad range of stable climates had none. It is inconsistent with both logic and the oral traditions of the region. Plus, recently, an enormous city, predating at least much of the flood, has been found off the Indian coast. In other words, the default assumption should be that civilization began there and then. It may prove to be false, but it is more probable than the assumption that the Sumerians were the first civilization simply because they are the oldest we have found. "Before the Flood" is not intended to be one more 'lost civilization' popular culture book, but rather an academic assault on one specific academic premise.
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In Did You Know? the National Geographic magazine team shares extra information we gathered to expand your knowledge of our featured subjects.
Troglobitic Paradise Caves, homes for the world’s troglobites, can be created by volcanic eruptions. When hot molten lava flows downhill, it is slowly capped by freshly cooled rock and a lava tube forms. Once the erupting volcano stops, the resulting empty channel, or lava tube, remains. Being fragile, new tubes forming above older ones often cause the ceilings of the older tubes to break, joining the two together. Lava tubes, which lie close to the Earth’s surface, are usually less than 20 million years old. Fairly young on the geologic time scale.
Lava tubes frequently trap moisture, which can then be tapped by thin-rooted trees that reach through the tube’s surface while colonizing the rock above. The combination of dangling tree roots and moist, stable air creates a perfect habitat for many troglobites. Bayliss Cave in Australia is a lava tube with one of the most diverse troglobitic communities in the world, 24 known species.
One inhabitant of lava tubes in Hawaii is the Kauai wolf spider. Closely related to a surface-dwelling wolf spider with large eyes, the Kauai is often referred to as the “no-eyed, big-eyed wolf spider.” Producing fewer offspring than its relative, the female Kauai wolf spider will carry her spiderlings on her back after they hatch until the youngsters are ready to leave and hunt on their own. With only three populations of this troglobitic spider known to exist, the U.S. Fish and Wildlife Service listed it on the endangered species list in January 2000.


First of three search expeditions for the White Bird, the aircraft flown by Nungessor & Coli, who vanished on transatlantic flight in 1927. October, 1984.
Early on May 8, 1927, twelve days before Charles Lindberg was to make his historic flight, two famous WWI French flying aces took off from Le Bourget airfield near Paris on an east to west flight across the Atlantic to New York. They were one of the first who successfully managed to get off the ground with a fuel-over laden airplane and soar out over the Atlantic.
Charles Nungesser and Francois Coli were already the toast of France. Nungesser had shot down 44 German planes and barnstormed in Europe and the United States after the war. Coli was also an ace, but later gained fame on a long distance flight to Africa.
After takeoff the L’Oiseau blanc (the White Bird), a Levasseur bi-wing, open cockpit aircraft powered by a 450 horsepower Lorraine-Dietrich 12 cylinder engine, dropped its landing gear and flew out over the English Channel. It was last sighted heading over the ocean from the eastern shore of Ireland.
The White Bird then simply vanished and was never seen again. It was not until 1980 when Gunnar Hanson, a freelance writer, researched and published an article on a man by the name of Anson Berry who was living near Machias, Maine, in 1927 and who claimed to hear an aircraft fly over his isolated camp late in the afternoon of May 9th, 1927. Anson, told several friends and neighbors he had heard the plane overhead in the overcast and but could not see it. He also stated the engine sounded erratic and it sounded to him as if the plane crashed in the distance.
Gunner dug deeper and found a number of other reports and a few sightings beginning in Newfoundland and traveling on a line south past Nova Scotia and into the coastal region of Maine. He then ran onto a report by a hunter who said he’d found an old engine buried in the ground sometime in 1950. The site was within a mile of where Anson Berry heard the plane pass.
Gunner organized a group, including the hunter, a gentleman by the name of Ray Beck of Chatham, New York. Coincidentally, Bob Fleming and I were also researching the mysterious flight and heard about Gunner. I contacted him, offered to fund some of the search and flew up to Bangor, Maine.
The country is beautiful, and in the bog areas impossible to penetrate. The first trek we accomplished very little. While preparations were made for a second attempt, I contacted the well respected psychic, Ingo Swann, and asked him to take a crack at it.
He accompanied us on the second try and we came up dry. At the same time there was a group led by a Rick Gillespie who was also searching for the lost plane. Interestingly he didn’t know about our efforts. None of us wished to join his organization because he lived on media hype. And my feeling has always been not to make a big deal out of an expedition unless you can prove you actually discovered your intended target.
Swann later arranged for an experiment with several other psychics. Strange as it seems, working separately they all put the downed aircraft within a quarter of a mile from each other’s projections on the southern slope of the Round Hills near Round Lake.
What can I say. We combed the area foot by foot on the third attempt. The White Bird isn’t there.
The search goes on, however. No one wants to quit.
My personal theory, two in fact, is that it did not come down near where Anson Berry heard it, but some miles further south. Or, and I like this over any others, the plane went down in an impenetrable bog and chances of it ever being found are quite nil.


[EnergyBulletin] The future will be just like today, only tougher. Oil depletion is basically just a matter of overpopulation — too many people and not enough resources.
The most serious consequence will be a lack of food. The problem of oil therefore leads, in an apparently mundane fashion, to the problem of farming.
What to Grow
The most practical diet would be largely vegetarian, for several reasons. In the first place, vegetable production requires far less land than animal production. Even the pasture land for a cow is about one hectare, and more land is needed to produce hay, grain, and other foods for that animal.
How Much Land?
The amount of land needed for farming with manual labor would depend on several factors: the type of soil, the climate, the kinds of crops to be grown. The highest-yielding varieties are not necessarily the most disease-resistant, or the most suitable for the climate or the soil, or the easiest to store. The weather also makes a big difference: too little rain can damage a crop, and too much rain can do the same. Unusually cold weather can damage some crops, and unusually hot weather can damage others. Without irrigation — relying solely on rain — the yield is less than if the crops were watered.


Hi! Some of you may be looking for my research website. It's here.
Saturday, December 24, 2016
Wednesday, July 13, 2016
Wednesday, May 11, 2016
Monday, December 28, 2015
|Click pictures to embiggen|
A lot of natural history comes from patience, from watching for events that only happen rarely, and then are over, in the blink of an eye. There are, of course, some very spectacular natural events that aren't exactly sneaking up on you. More like, they walk up to you and grab your attention by the collar. Collective behaviour, has definitely been one of these: a large number of organisms doing things all at once, and somehow, together. Crowds, swarms, flocks, schools, all sorts of collectives are being studied. Advances in theory, measurement and notions of emergent behaviour have all led up to this.
The emergence of red sided garter snakes (Thamnophis sirtalis parietalis) in Narcisse, in Manitoba is most certainly a collective event. And the sheer number and coordination is impressive. How do thousands of these animals time their collective exit so exactly? How do they know that now is the time to crawl to the surface for their annual spring orgy? A few thousand snakes out at the same time is definitely the thing that brings so many people out to Narcisse, in the middle of the otherwise featureless flat Manitoba plains. But it isn't necessarily the most interesting thing going on here.
Well, what is going on here?
Before there were the flat lands, there was a first a huge ice sheet and then a huge lake in Manitoba, lake Agassiz. Agassiz was formed from the melt waters of that glacial ice sheet from the last ice-age. The ice-sheet was so large and heavy that Manitoba may still be undergoing isostatic rebound (i.e. the land-mass is still lifting back up after a weight was removed from it!). It is the reason the land is so flat and featureless, the ice sheet scraped everything down to nothing.
So where did all the water go?
Some of it remains in the remnant lakes, lake Manitoba and lake Winnipeg, that are nearly large enough to rival the great lakes. Some of it went underground and carved very deep caves into the bedrock. Some of these caves are so far below under the ground, that they are below the frost line. When winter comes to Manitoba and surface temperatures drop below -30 degrees Celsius, in these deep caves, its still above freezing. So at some point in the geological and evolutionary history of Manitoba, red-sided garter snakes started using these caves to hibernate. In the fall they go underground and they sleep off the winter there. Come spring, when the temperature is a bit more conducive to a happy life for a cold-blooded animal, they all wake up nearly at once and out they come!
And when you see the numbers, its seems like it is all at once, a few thousand at once. This is already quite the feat: for a few thousand snakes to time their metabolism so they can all emerge within a day or so of each other. But it's not even the best of it, it gets even more interesting. It isn't all at once. Males tend to come out first, when it still isn't quite warm enough outside. And once they are out, they hang around, soaking up what little watery sun they can get; here they wait. They're waiting for the females.
When the females do wake up and make their way out of the cave, a whole bunch of males are waiting for them right at the entrance. The males will then proceed to chase every single female as she comes out of the cave. Several males chase every single female that comes within their ambit. They try their best to align their bodies up against the females, to wrap around her and to mate with her, all the while signalling to her with pheromones and by rub her with their chins. If enough of them try to do this at the same time, it leads to balls of snakes wound tightly around each other, often known as mating balls.
|A mating ball|
Sometimes a mating ball is all male.
Some males will pretend to be female in order to attract courtship from other males. The snakes seem to recognize each others sex only through pheromones which they detect on each others skin. Snakes don't have external genitals and male hemipenises are held inside the body and everted from the cloaca only during mating. So all the males need is a chemical disguise. So gender-bending males produce female pheromones and this is enough to fool the other males into courting it and making mating balls around it.
Why on earth though? Well, for the one thing that most cold-blooded animals are short of: warmth. The core of a mating ball is warm and is constantly being warmed up by the bodies that pile up around it. Typically these 'transvestite 'males come out later than the other males, they might be in worse physical condition, and so cold and unable to court other females by themselves. By attracting a mating ball around themselves, they can raise their body temperature a few degrees. For a cold-blooded animal, that's a pretty big deal. When this is done, the gender bending males seem to turn the female pheromone off magically. With the other males no longer pursuing them, they get down to finding some mates of their own. In fact, the current theory is that the female pheromone has just the right degree of volatility: when the male's body temperature rises to where it needs it to be, the pheromone just evaporates off on it's own!
There can be a cost to this trickery, a cost some females pay and some males probably do as well. The mating ball is a pretty frantic affair. These congregations last only a few days, so the urge to get it on is very very strong. And sometimes the mating balls end up suffocating the female they are formed around. With the males there is the added fear of injury from forced copulations. So this strategy isn't without risk, but what a cool adaptation!?
In almost all systems, there's a lot of amazing detail beyond the obviously impressive spectacle and I hope we can keep looking beyond the obvious and finding it.
Have a great Christmas break, guys!
PS: A lot of the research done here was done in the labs of Richard Shine and Robert T Mason in case you want to read some of the primary literature.
Friday, November 13, 2015
Respost for folks from Reddit.
Here's some sense of how the whole process goes. The series also gives you an idea of how long I spent on getting these images. Its only towards the completion of the second or even third pot that I got what I wanted. I think it took a week I think before I nailed the lighting and focus.
I wanted the wasp completely in focus, so absolutely parallel to the lens plane. So I watched it to figure out its behavior and realized it would hover in front of the pot for just a couple of seconds before landing. So I rigged the tripod to be just low enough to be eye level to the wasp and just parallel to its incoming flight path.
My only light source was either natural light or my handheld manual Vivitar 5000. I did have an extension cable at least. Initially I just worked on getting the exposure right so I got nice wing blur but a stable insect. You can see their bodies are quite still, even when their wings move.
Then I worked on getting enough light on the wasp and on the wall behind the wasp. If you held the light parallel to the wasp body, the light on the wall fell off very fast and the right edge of the image was too dark. Not to mention the ugly shadow of the pot either below or beside the pot (See images 2, 3 and 4). I didn't have a second flash to do a fill light. (I was a poor grad student then.)
So the light had to be held just so. Once the wasp was hovering, the ring-light was held behind it so the insect was in its centre. And the light was tilted towards the wall, so off at an angle to the wasp and pushing more light to the wall, behind the pot. The light is also slightly above the wasp, pointing down a bit as you can infer from the specular highlights and shadows. This last part wasn't necessarily intended, but altogether it worked. The image hangs together
As you can see there is still some fall off on the wall and the front of the mud ball and the face of the wasp is not as highly lit as the thorax and abdomen. But both those are acceptable compromises. The image hangs. And that is how I made this image. I didn't click it, I didn't snap it, no, no, I stalked it and I made it.
|Bring mud to make pot|
|Shape pot out of the mud brought in|
|Stock the pot with alive but paralysed soft bodied prey like caterpillars and spiders.|
|Lay a single egg and seal the pot. See sealed pot in image no 1.|
Wednesday, September 30, 2015
The Don valley parkway was closed this weekend. But it was very very busy in other ways. A few million midges had an end of summer party over it!
They had fireworks and everything!
It was quite the show. Summer got a grand send off.
Copyright © Natasha Mhatre If you're reading this without attribution to me anywhere other than at my blog Talking Pictures, its probably being plagiarized.
Tuesday, July 21, 2015
Tuesday, June 23, 2015
Monday, May 25, 2015
Tuesday, May 05, 2015
Saturday, May 02, 2015
Friday, April 10, 2015
Monday, March 02, 2015
I know that some of you came here to look at my science art. You may be interested in the fun and games at the #SciArt hash-tag. Don't bother with the 'Is it art' question. No line has been drawn between art, craft, illustration or doodling by anyone at all. This is Twitter after all but its fun nonetheless. Have a look.
To look at my word beasts
To look at my word beasts


These top 10 strange holes are geographical phenomena and most astounding sites in the world. Some hole are made occasionally by nature but some by the man in search for the mining wealth. Here we point out the top ten biggest and strangest of them.
1. Darvaza Gas Crater – Turkmenistan (The Door to Hell):
In the heart of the Karakum desert of Turkmenistan the Darvaza Gas Crater or The Burning Gates give off a glow that can be seen from miles away during the dark night. The large crater is a result of a Soviet gas exploration accident in the 1950’s. It was created when a Soviet drilling rig was drilling for natural gas fell into an underground cavern resulting in a crater which today measures roughly 60 meters in diameter and 20 meters deep. The huge crater was set alight shortly after being discovered and has been burning ever sinse. The smell of burning sulfur can be detected from a distance and becomes quite strong as you near the hot edge of the crater.
2. Kimberley Diamond Mine – South Africa:
The Kimberley Diamond Mine (also known as the Big Hole) holds the (disputed) title of being the largest hand-dug hole in the world. From 1866 to 1914 50,000 miners dug the hole with picks and shovels, yielding 2,722 kg of diamonds. Attempts are being made to have it registered as a world heritage site. The Big Hole has a surface of 17 hectares (42 acres) and is 463 metres wide. It was excavated to a depth of 240 m, but then partially infilled with debris reducing its depth to about 215 m; since then it has accumulated water to a depth of 40 m leaving 175 m visible. Beneath the surface, the Kimberly Mine underneath the Big Hole was mined to a depth of 1097 metres. A popular local myth claims that it is the largest hand-dug hole on the world, however Jagersfontein Mine appears to hold that record.
3. Monticello Dam – California:
Monticello Dam is a dam in Napa County, California, constructed between 1953 and 1957. The dam is a medium concrete-arch dam with a structural height of 304 ft (93 m) and a crest length of 1,023 ft (312 m). It contains 326,000 cubic yards (249,000 m³) of concrete. The dam impounds Putah Creek to form Lake Berryessa, the second-largest lake in California. The capacity of the reservoir is 1,602,000 acre·ft (1,976,000 dam³). Water from the reservoir is supplied mostly to the North Bay area of San Francisco. The dam is noted for its classic, uncontrolled spillway with a rate of 48,400 cubic feet per second (1370 m³/s) and a diameter at the lip of 87 ft (27 m).
4. Bingham Canyon Mine – Utah
The Bingham Canyon Mine is a copper mine in the Oquirrh mountains, Utah. The mine is 0.75 mile (1.2 km) deep, 2.5 miles (4 km) wide. It is the world’s largest manmade excavation. The mine has been in production since 1906, and has resulted in the creation of a pit covering 1,900 acres (7.7 km²). Over its life, Bingham Canyon has proven to be one of the world’s most productive mines. As of 2004, ore from the mine has yielded more than 17 million tons (15.4 Mt) of copper, 23 million ounces (715 t) of gold, 190 million ounces (5,900 t) of silver, and 850 million pounds (386 kt) of molybdenum.
5. Great Blue Hole – Belize
The Great Blue Hole is an underwater sinkhole off the coast of Belize. The hole is 1,000 feet across and 400 feet deep. It was formed as a limestone cave during the last iceage. This is a popular spot amongst recreational scuba divers, who are lured by the opportunity to dive in crystal clear water and meet several species of fish, including giant groupers, nurse sharks and several types of reef sharks such as the Caribbean reef shark and the Blacktip shark.
6. Mirny Diamond Mine – Siberia:
The Mirny Diamond Mine is 525m deep and has a diameter of 1200m. It was the first, and one of the largest, diamond Pipes in the USSR. It is now abandoned. While it was still operational, it would take two hours for trucks to drive from the top to the bottom of the mine. Currently, the mine is operated by Alrosa, the largest diamond producing company in Russia, and employs 3600 workers. It has long been anticipated that the recovery of diamonds by conventional surface methods will saturate. Therefore, in 1970s construction has started of a network of underground tunnels for diamond recovery. Production of diamonds by this method started in 1999 and is estimated to last for another 27 years. This estimate is based on depth explorations down to 1220 meters. In order to stabilize the abandoned main pit, its bottom was covered by a rubble layer 45 meters thick.
7. Diavik Mine – Canada
The Diavik Mine is a mine in the Northwest territories of Canada. The mine (opened in 2003) produces 8 million carats or about 1,600 kg (3,500 lb) of diamonds every year. The mine is owned by a joint venture between the Harry Winston Diamond Corporation and Diavik Diamond Mines Inc., a subsidiary of Rio Tinto Group. The lifespan of the mine is expected to be 16 to 22 years. The mine consists of three kimberlite pipes associated with the Lac de Gras kimberlite field and is located on an island 20 square kilometres (8 sq mi) in Lac de Gras and is informally called East Island. It is about 220 kilometres (137 mi) south of the Arctic Circle.
8. Sinkhole – Guatemala:
In February 2007 a large sinkhole opened in a poor neighborhood in northeast Guatemala city, killing three people. The sinkhole was 100.5 m (330 ft) deep, and apparently was created by fluid from a sewer dissolving the rock underneath. As a result, one thousand people have been evacuated from the area. The sink hole has since been mitigated and plans to develop on the site have been proposed.
9. Udachnaya Pipe – Russia:
The Udachnaya Pipe is a diamond mine in Russia. The owners of the mine plan to cease its operations in 2010 – in favor of underground mining. The mine was discovered in 1955 and is over 600 meters deep. The nearby settlement of Udachny is named for the deposit. As of 2004,Udachnaya pipe is controlled by Russian diamond company Alrosa, which plans to halt open-pit mining in favor of underground mining in 2010
10. Chuquicamata – Chile
Chuquicamata or “Chuqui” as it is more familiarly known, is an open pit copper mine in Chile. It is the mine with the largest total production of copper in the world – though it is not the largest copper mine. The mine is over 850 meters deep. Copper has been mined for centuries at Chuquicamata as was shown by the discovery in 1898 of “Copper Man”, a mummy dated at about 550 A.D. which was found trapped in an ancient mine shaft by a fall of rock. It is also said that Pedro de Valdivia obtained copper horseshoes from the natives when he passed through in the early 16th Century.


Everyone nowadays knows the life of Alexander Hamilton, thanks to the critically-acclaimed musical Hamilton. But what about the life of infamous and controversial president Andrew Jackson? Sure, he forced thousands of Native Americans on the Trail of Tears, and as a result, he has recently been taken off the face of the 20 dollar bill, but he had his moments of glory and he definitely left his mark on American history. Often called the worst “great” president, maybe there is more to the life of the founder of the Democratic Party than his legacy. In this comedic historical rock musical, reexamine the facts as America’s seventh president is reinvented on stage with this production of Bloody Bloody Andrew Jackson.
Textbooks can only do so much. Watch history come alive onstage at the Power Center on November 17 and 18 at 8pm and November 19 at 2pm.
Tickets are available at Michigan Union Ticket Office for $7 or can be bought online at https://www.ummusket.org/


Banknotes of Canadian Dollars (CAD)
The first paper money issued in Canada denominated in dollars were British Army Bills, issued between 1813 and 1815 in denominations between $1 and $400. These were emergency issues due to the War of 1812. The first banknotes were issued in 1817 by the Montreal Bank. Large numbers of chartered banks were founded in the 1830s, 1850s, 1860s and 1870s, although many issued paper money for only a short time. Others, including the Montreal Bank (later called the Bank of Montreal), issued notes for several decades. Until 1858, many notes were issued denominated in both shillings/pounds and dollars (5 shillings = $1). A large number of different denominations were issued, including $1, $2, $3, $4, $5, $10, $20, $25, $40, $50, $100, $500 and $1000. After 1858, only dollar denominations were used. See Canadian chartered bank notes for more information.
After its establishment in 1841, the Province of Canada began issuing paper money. Notes were produced for the government by the Bank of Montreal between 1842 and 1862, in denominations of $4, $5, $10, $20, $50 and $100. In 1866, the Province of Canada began issuing its own paper money, in denominations of $1, $2, $5, $10, $20, $50, $100 and $500. In 1870, following Confederation, the Dominion of Canada introduced 25¢ notes along with new issues of $1, $2, $500 and $1000. $50 and $100 notes followed in 1872 but the bulk of later government note production was of $1 and $2 note, with $4 added in 1882. Denominations of $500, $1000, $5000 and $50,000 were issued after 1896 for bank transactions only.
The Bank Act of 1871 limited the smallest denomination the chartered banks could issue to $4, increased to $5 in 1880. To facilitate purchases below $5 without using Dominion notes, Molsons Bank issued $6 and $7 notes in 1871. The government issued $5 notes from 1912. The last 25¢ notes, known as shinplasters due to their small size, were dated 1923.
In 1935, with only ten chartered banks still issuing notes, the Bank of Canada was founded and began issuing notes in denominations of $1, $2, $5, $10, $20, $50, $100, $500 and $1000. In 1944, the chartered banks were prohibited from issuing their own currency, with the Royal Bank of Canada and the Bank of Montreal among the last to issue notes.
Although the $1 coin was introduced in 1935, it was not until the introduction of the "loonie" that the banknote was withdrawn from circulation. The $2 note was also replaced by a coin in 1996. All banknotes are currently printed by the Canadian Bank Note Company and BA International Inc on behalf of the Bank of Canada.


February 26, 2001
'TITANIC: The Artifact Exhibit'
sails into Pacific Science Center
by Deborah Stone
On the ill-fated night of Sunday, April 14, 1912, just days into its maiden voyage, the famed ocean liner Titanic hit a large iceberg, south of Newfoundland.
A few hours later, the ship sank bow first and then broke in half, claiming the lives of 1,523 passengers and crewmembers.
This legendary disaster captured the world's attention and over the years it has continued to fascinate people.
Movies, musicals and books have been penned to tell the story of one of the greatest maritime tragedies of all time and now "TITANIC: The Artifact Exhibit" has been created to allow visitors an eye-opening view of some of the remains of the once touted "unsinkable" ship.
The exhibit, which is currently on view at Pacific Science Center in Seattle, presents the history, science and drama of the Titanic utilizing full-scale scenic environments, re-creations of its famous rooms, hundreds of artifacts, a conservation lab and a memorial display.
Visitors can view the world's largest collection of Titanic artifacts recovered from 2.5 miles below the ocean's surface, including a massive 15-ton, 13-by-28 foot portion of the ship's hull and numerous personal effects such as letters, jewelry, eyeglasses and clothing.
In re-created rooms, visitors can tour an elegant first-class cabin, a third-class cabin and a full-scale replica of the luxurious grand staircase.
A large wall of ice, close to the temperature of the Atlantic Ocean on that terrible night, offers a tangible way for guests to identify with what passengers on board Titanic endured as they struggled for their lives in the frigid water.
In the conservation lab, the science behind the recovery and restoration of the artifacts is detailed with a demonstration of the techniques used to restore discovered items.
Unforgettable stories of passengers and crew who either miraculously survived or tragically perished in the disaster are told in the memorial section.
Fifty-six passengers on board the Titanic had the Pacific Northwest as their destination.
To accompany the exhibit, the IMAX film "Titanica" will show daily, featuring images of Titanic on the ocean floor, contrasted with archival photos of the ship taken in 1912 and the poignant memories of Titanic survivor Eva Hart.
Award-winning filmmaker Stephen Low shot the film during a 1991 expedition to the wreckage site.
"TITANIC: The Artifact Exhibit" helps visitors to gain appreciation and understanding of the history behind this terrible disaster, all within the context of the opulent Edwardian era.
The exhibit runs through Sept. 3 and tickets are now available at all Ticketmaster outlets, by phone at (206) 292-ARTS or online at www.titanicseattle.com. Tickets are sold on a timed-entry basis, due to the predicted popularity of the exhibit.


A community of native fishers and an army detachment had a temporary residence in Wrangel Island, in a settlement called Ushakovskoye. That was in soviet times. The hamlet was then abandoned and only now starts to a new life - a protected natural reserve and some adventure tourism.
Wrangel Island (Russian: о́стров Вра́нгеля) is an island in the Arctic Ocean, between the Chukchi Sea and East Siberian Sea. Wrangel Island lies astride the 180° meridian.
Coordinates: 71°59′ N, 179° 25 W
The International Date Line is displaced eastwards at this latitude to avoid the island as well as the Chukchi Peninsula on the Russian mainland. The closest land to Wrangel Island is tiny and rocky Herald Island located 60 km to the eas. The Siberian coast is 140 km away through the Chukchi sea.
Wrangel Island is a protected nature sanctuary. The island, and their surrounding waters, were classified a "strict nature reserve" in 1976 and, as such, receive the highest level of protection and excludes practically all human activity other than for scientific purposes.
Several animal species are also protected, and the polar bear community is the largest in the world.
As of 2003, there were four rangers residing on the island year-round. In addition a core of about 12 scientists conduct research during the summer months.
Wrangel Island is about 125 km wide and 7,600 km2 in area. It consists of a southern coastal plain; a central belt of low-relief mountains; and a northern coastal plain
In 2004 Wrangel Island and neighboring Herald Island, along with their surrounding waters, were added to UNESCO's World Heritage List
After some attempts from the U.K., Canada and the U.S. to claim possession, the Soviet Government, in 1926, declared its sovereignty over the island; and, to confirm this, Ushakovskoye was founded on August 14, 1926.
The initial population of the settlement included displaced Chukchi and Russian families, totalling about 60 people. The settlers established themselves on the island and few chose to return to the mainland after their first posting ended in 1929.
Indeed, so successful was the initial settlement that resulted in the founding of Ushakovskoye, that a second village, Zvyozdny (meaning Star) was founded some 30 km west of Ushakovskoye on the shores of Somnitelnaya Bay.
Zvyodny setllement, where a house is kept functional to accomodate rangers and visitors.
Zvyozdny would later become the landing point for supplies delivered to the island from Mys Shmidta as well as mail, which would be delivered to Ushakovskoye along the dirt track which links the two settlements.
Ushakovskoye grew and developed, until at the end of 1970 it had a school, club, shop, post office, hospital and electricity was supplied to the homes, as well as a modest museum of natural history, an underground repository in the permafrost for storing meat, the polar station "Rogers Bay", library and a communal bath !
Ushakovskoye as seen from the sea
In 1984 the population had grown to around 180 people. But in they 1990s, subsidies were reduced and in 1994 the last supply ship brought provisions and fuel to the settlement.
The settlement of Zvyozdny was being abandoned as well. However, a helipad had been constructed in Ushakovskoye in 1966, so the village could continue to be supplied.
In 1997, it was decided to resettle the inhabitants at Mys Shmidta. The last resident was killed by a polar bear on October 13, 2003.
Ushakovskoye, Rogers Inlet
Ushakovskoye is presently a ghost town on the south coast of Wrangel Island. It used to house up to 200 residents, but at the end of the Soviet era, was largely abandoned. The only human residents nowadays are the Wrangel Island rangers and the occasional scientific researchers.
Regularly-seen animals and birds in town include snowy owls, arctic foxes, musk oxen, reindeer herds, and of course, polar bears.
Snow geese in flight
Professor Khromov', prepared to face sea ice, is a frequent visit to Wrangel Island. The trips start at the local capital Anadyr.
Full moon over Zvyozdny


Do you perhaps mean
y = (1/2) x
If so, when x = 0, y = 0
If it is really
y = 1/(2x)
then when x = 0, y is undefined.
it really means y= 1/2 x
Does x have to represent 0? I need to know why
The y axis intercept is the value of y when x = 0
because any old function that crosses the y axis does so along the vertical line x = 0
This one never quite hits the vertical axis
the question says to list the ordered pair,is the ordered pair (0,0).Some of the questions give "undefined as an option, but not this question.
Well, 1/(2*0) is undefined
so I would have to say
where oo means infinity.
Are you absolutely sure you do not have a typo in the problem statement?
If it were y = x/2 the solution would be (0,0)
Graph the equation and identify the y intercept: y= one half*x or 1/2*x
The y intercept is____
type in the ordered pair.
That is the exact question
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This chapter discusses about following topics:
Introduction Types of Computer Software System Software Operating Systems Language and Language Processors Low Level language Machine Language Assembly language Assembler High Level Language Compiler Interpreter Utilities Application Software Tailored Software Packaged Software WordProcessing Systems Spreadsheet Systems Database Management Systems Presentation Systems Graphic Designing Web Browsers Email Clients Multimedia and Entertainment Customized Software Liveware Firmware Cache Memory
Software is the most important component of computer system. Without software, a computer turns into a dead body – a dead slave!
Software is a generic term for organized collections of computer data and instructions, often broken into two major categories: system software that provides the basic non-task-specific functions of the computer, and application software which is used by users to accomplish specific tasks. – Wikipedia
In other words, software is a set of programs, procedures, algorithms and its documentation concerned with the operation of a data processing system. Thus the software contains the instructions that tell a computer what to do and how to do to solve a specific problem.
In general use, by software we understand a group of programs to make a system run. A program contains instructions or commands to perform a task. The term package or suite is used to describe a group of related software.
Types of Software
System software is responsible for controlling, integrating, and managing the individual hardware components of a computer system so that other software and the users of the system see it as a functional unit without having to be concerned with the low-level details such as transferring data from memory to disk, or rendering text onto a display. Generally, system software consists of an operating system and some fundamental utilities such as disk formatters, file managers, display managers, text editors, user authentication (login) and management tools, and networking and device control software.
An operating system (OS) is a set of software that manages computer hardware resources and provides common services for computer programs. The operating system is a vital component of the system software in a computer system. Application programs require an operating system to function.
The operating system is the most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop – it makes sure that different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
Operating systems can be classified as follows:
Multi-user operating system : Allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users.
Multiprocessing operating system: Supports running a program on more than one CPU.
Multitasking operating system: Allows more than one program to run concurrently.
Multithreading operating system: Allows different parts of a single program to run concurrently.
Real time operating system: Responds to input instantly. General-purpose operating systems, such as DOS, Windows and UNIX, are not real-time.
Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. For PCs, the most popular operating systems are DOS, OS/2, and Windows, but others are available, such as Linux.
As a user, you normally interact with the operating system through a set of commands. For example, the DOS operating system contains commands such as COPY and RENAME for copying files and changing the names of files, respectively. The commands are accepted and executed by a part of the operating system called the command processor or command line interpreter. Graphical user interfaces allow you to enter commands by pointing and clicking at objects that appear on the screen.
Language and Language Processors
There are 2 types of computer languages: low level language and High level language.
Low Level Language
Machine language and assembly language are called low level language because they are used to write programs that deal with the low level tasks such as transferring data from memory to disk, or rendering text onto a display. Low level language is machine dependent i.e. a program written for one type of computer does not work on other computers. You need to know the details of a computer rather than problem for which you are writing programs.
The lowest-level programming language. Machine languages are the only languages understood by computers. While easily understood by computers, machine languages are almost impossible for humans to use because they consist entirely of numbers. It is tiresome and error prone to program in machine language. Programmers, therefore, use either a high-level programming language or an assembly language.
Every CPU has its own unique machine language. Because machine language is directly understood by computer you don’t need to convert it to run.
Assembly languages are between machine languages and high-level languages. Assembly languages are similar to machine languages, but they are much easier to program in because they allow a programmer to substitute names for numbers. Machine languages consist of numbers only.
So, assembly language is a much more readable rendition of machine language. It uses mnemonic codes to refer to machine code instructions, rather than using the instructions’ numeric values directly.
Assembly language is the most basic programming language available for any processor. With assembly language, a programmer works only with operations implemented directly on the physical CPU. Assembly language lacks high-level conveniences such as variables and functions, and it is not portable between various families of processors.
High Level Language
High level language is a machine-independent programming language, such as C, C++, Java, Perl and COBOL. It lets the programmer concentrate on the logic of the problem to be solved rather than the intricacies of the machine architecture such as is required with low-level assembly languages.
High level languages uses English like statements and mathematical notations. Because a programmer now does not need to remember the machine architecture and operations implemented directly on the physical CPU, high level languages are machine independent. They are often called problem oriented languages or business oriented language.
High level languages were developed towards the end of second generation of computers (COBOL and FORTRAN) and flourished during third and fourth generations. Pascal, C, C++, C#, LISP, Java, Basic etc. are the examples of high level language.
High level language is completely different than what machines can understand. To run a program written in high level language, you need to convert it into machine code. There are two kinds of language processors to convert high level language into machine language – interpreter and compiler.
A compiler is a language processor that converts the instruction of a high level language into machine language as a whole. Programs written in high level language is called source program and after it is converted into machine language by the compiler, it is called an object program.
Compiler checks each statement in the source program to generate machine instructions. Any syntax errors if existing in source program are discovered while analyzing. A source program containing an error cannot be compiled into an object program.
Each high level language has its own compiler. A compiler can translate the programs of only that language for which it is written. For example C++ compiler can translate only those programs, which are written in C++.
An interpreter is a language processor that converts one statement of high level language program at a time. It executes this statement before translating the next statement of the source program. If there is an error in the statement, the interpreter will stop working and displays an error message.
The advantage of interpreters over compilers is that an error is found immediately. So the programmer can make corrections during program development. Thus, interpreters are often used to debug program while debugging.
The disadvantage of interpreter is that it is not very efficient. The interpreter does not produce an object program. It must convert the program each time it is executed. Visual basic uses interpreter.
Utility software is system software designed to help analyze, configure, optimize or maintain a computer. Utility or a tool is the term used for a single piece of utility software. Utility software are also referred to as service program, tool, service routine, or utility routine.
Utility software usually focuses on how the computer infrastructure (including the computer hardware, operating system, application software, and data storage) operates. Utility software is often targeted at technical people with an advanced level of computer knowledge.
You can find utilities in different categories, such as:
Anti-virus utilities scan for computer viruses. Backup utilities can make a copy of all information stored on a disk, and restore either the entire disk (e.g. in an event of disk failure) or selected files (e.g. in an event of accidental deletion). Data compression utilities output a shorter stream or a smaller file when provided with a stream or file. Disk checkers can scan operating hard drive. Disk cleaners can find files that are unnecessary to computer operation, or take up considerable amounts of space. Disk cleaner helps the user to decide what to delete when their hard disk is full. Disk compression utilities can transparently compress/uncompress the contents of a disk, increasing the capacity of the disk. Disk defragmenters can detect computer files whose contents are broken across several locations on the hard disk, and move the fragments to one location to increase efficiency. Disk partitions can divide an individual drive into multiple logical drives, each with its own file system which can be mounted by the operating system and treated as an individual drive. Archive utilities output a stream or a single file when provided with a directory or a set of files. File managers provide a convenient method of performing routine data management tasks, such as deleting, renaming, cataloging, uncataloging, moving, copying, merging, generating and modifying data sets. Cryptographic utilities encrypt and decrypt streams and files. Hex editors directly modify the text or data of a file. These files could be data or an actual program. Memory testers check for memory failures. Network utilities analyze the computer’s network connectivity, configure network settings, check data transfer or log events. Registry cleaners clean and optimize the Windows registry by removing old registry keys that are no longer in use. Screensavers were desired to prevent phosphor burn-in on CRT and plasma computer monitors by blanking the screen or filling it with moving images or patterns when the computer is not in use. Contemporary screensavers are used primarily for entertainment or security. System monitors for monitoring resources and performance in a computer system. System profilers provide detailed information about the software installed and hardware attached to the computer.
Application software, is used to accomplish specific tasks other than just running the computer system. Application software may consist of a single program, such as an image viewer; a small collection of programs (often called a software package) that work closely together to accomplish a task, such as a spreadsheet or text processing system; a larger collection (often called a software suite) of related but independent programs and packages that have a common user interface or shared data format, such as Microsoft Office, which consists of closely integrated word processor, spreadsheet, database, etc.; or a software system, such as a database management system, which is a collection of fundamental programs that may provide some service to a variety of other independent applications.
Software is created with programming languages and related utilities, which may come in several of the above forms: single programs like script interpreters, packages containing a compiler, linker, and other tools; and large suites (often called Integrated Development Environments) that include editors, debuggers, and other tools for multiple languages.
Types of application software:
You can group application software into two categories – tailored or customized software and packaged software. You can find other categories that lie in between the tailored and packaged.
There are many tasks in an organization or office that can be automated by writing specific software programs. For example SLC board has developed its own software solution for result processing. Provident Fund (Sanchaya Kosh) has developed its own software to record, calculate and perform many other operations. All these software developed are known as tailored software.
Tailored software are the applications developed to solve or automate a particular task of an individual or organization.
Tailored software are developed by employing or hiring a system design and development team who perform system study and find best alternative to solve the problem at hand. They analyze, design new system, develop, testing, debugging and implementation. When the software is ready to do its work, it is handed over to the organization.
Many software houses study the general requirement of computer users and develop software packages. Software packages are aimed at solving some common problem such as word-processing, spreadsheet calculation, database management, presentation systems and so on.
Package software are complex and with less bugs because it is developed often by a large professional team. So they are more reliable compared to tailored software.
Microsoft Office Suite, Lotus Suite, Open Office Suite, Adobe Creative Suite etc. and their individual applications are the examples of packaged software.
Categories of packaged software:
WordProcessing Systems – MS Word, Lotus Write, WordPerfect
Spreadsheet Systems – MS Excel, Lotus 123,
Database Management Systems – MS Access, MySql, Oracle, MS SQL Server
Presentation Systems – MS PowerPoint
Graphic Designing – Adobe PhotoShop, CorelDraw
Web Browsers – Internet Explorer, Firefox, Google Chrome
Email Clients – Microsoft Outlook, Eudora Pro
Multimedia and Entertainment –Windows Media Player, xDiv DVD Player, VLC Player, and computer games
Apart from tailored and packaged software there is another software type called customized software. These are the software applications that are modified or customized to meet your specific need after acquiring some pre-built packaged software. For example you can get MS Excel or Access and use its macro feature or write some other add-ins, or extensions, to solve your particular problem. Any software developed this way is known as customized software.
Liveware is a slang term used to denote people using (attached to) computers, and is based on the need for a human, or liveware, to operate the system using hardware and software. It was used in the computer industry as early as 1966 to refer to computer users, often in humorous contexts by analogy with hardware and software. Other words meaning the same or similar to liveware include wetware, meatware and jellyware.
The term firmware is often used to indicate the control programs stored in ROM chips. Typical examples of devices containing firmware are embedded systems, computers, computer peripherals, mobile phones, and digital cameras. The firmware contained in these devices provides the control program for the device.
Firmware is held in non-volatile memory devices such as ROM, EPROM, or flash memory. Changing the firmware of a device may rarely or never be done during its economic lifetime; some firmware memory devices are permanently installed and cannot be changed after manufacture.
Common reasons for updating firmware include fixing bugs or adding features to the device. This may require physically changing ROM integrated circuits, or reprogramming flash memory with a special procedure. Firmware such as the ROM BIOS of a personal computer may contain only elementary basic functions of a device and may only provide services to higher-level software. Firmware such as the program of an embedded system may be the only program that will run on the system and provide all of its functions.
Cache (pronounced cash) memory is extremely fast memory that is built into a computer’s central processing unit (CPU), or located next to it on a separate chip. It is usually a small amount (normally less than 1MB) of high-speed memory residing on or close to the CPU. Cache memory supplies the processor with the most frequently requested data and instructions. The CPU uses cache memory to store instructions that are repeatedly required to run programs, improving overall system speed. The advantage of cache memory is that the CPU does not have to use the motherboard’s system bus for data transfer. Whenever data must be passed through the system bus, the data transfer speed slows to the motherboard’s capability. The CPU can process data much faster by avoiding the bottleneck created by the system bus.
As it happens, once most programs are open and running, they use very few resources. When these resources are kept in cache, programs can operate more quickly and efficiently. All else being equal, cache is so effective in system performance that a computer running a fast CPU with little cache can have lower benchmarks than a system running a somewhat slower CPU with more cache. Cache built into the CPU itself is referred to as Level 1 (L1) cache. Cache that resides on a separate chip next to the CPU is called Level 2 (L2) cache. Some CPUs have both L1 and L2 cache built-in and designate the separate cache chip as Level 3 (L3) cache.
Points to Remember
- Computer in itself is nothing more than a slave in a box. Computer hardware is like a dead body which has all the machinery and mechanism but can’t do anything. A computer requires programs and instructions to do each and every tasks.
- A set of self-contained instructions that tells a computer how to solve a problem or carry out a task is called a program. A group of programs that are put into a computer to operate and control its activities is called software.
- Software are classified broadly into two types – system software and application software. Loosely, you can understand it as all the software developed to help user to perform his/her required tasks are application software. And similarly, all the software developed to operate computer and help it to be able to run user required applications are system software.
- System software is a set of programs that organizes, utilizes and controls the hardware in a computer system. It serves as intermediary between hardware and application software. System software supports – running other software, communicating with peripheral devices, development of other types of software, monitoring the use of hardware resources.
- Operating systems, utility programs, device drivers and language processors fall into the class of system software.
- Operating system is a type of system software that controls and coordinates the internal working of a computer system. The major function of operating system are – provide user interface to the user; manage disks, devices and other resources; provide platform to run other software; load applications as and when user requests.
- Microsoft launched GUI operating environment called Windows in November 20, 1985.
- Device drivers are the system software that controls a particular type of device installed in computer. Device drivers has instructions to make operating system able to recognize and operate the device. Device drivers work as intermediary between the hardware device and operating system.
- Utility software are system software that are designed to help analyze, configure, optimize and maintain the computer system. It performs the specific task related to the management of computer functions, resources, or files as password protection, memory management, virus protection and file compression.
- Many operating systems have some utility programs build directly into the operating system itself. Other utility programs are sold separately as software packages that the user must install.
- Disk tool kits, data compression utilities, backup utility programs, virus protectors and screen savers are some utility programs.
- Disk defragmenters are utilities that analyse the fragmentation (pieces of a file scattered on different location in disk surface) and move the pieces into one place to improve computer performance.
- Disk checkers like chkdsk, scandisk can scan the contents of a disk to find files or disk areas that are corrupted in some way.
- Disk cleaners can identify files that are unnecessary to computer operation and can delete them on your permission.
- Computers can understand instructions that are in machine language. Any program that is not in machine language must be translated into machine language to execute. A program that translates user’s program into machine language are language translators or language processors.
- Assembler, compiler and interpreters are the types of language processors.
- Assembler translates a program written in assembly language into machine language. It creates a converted file that is executable in computer. Smalltium, MASM, TASAM are some examples of assembler.
- Compiler is a language processor that translates a high level language program into machine code in a single operation. It creates machine language file that can be executed in computer. Programming languages like C, C++, Java, FORTRAN uses compilers.
- Interpreter is a language processor that translates each statement of user programs in turn into machine code for the computer to execute. Interpreters do not create machine code file but rather run every instruction after it is converted one after another.
- Application Software is a class of computer programs that help users to solve their problems. Application software are also known as applications or apps.
- Examples of application software are word processors, database programs, web browsers, development tools, drawing, paint, and image editing programs, communication programs.
- API (Application Programming Interface) is a formal request for services and means ofnicating with other programs that a programmer uses in writing an application program.
- Application software are further classified into packaged software and tailored or customized software.
- Packaged software is a generalized set of programs that allows the computer to perform a specific data processing job for the user. Some of the popular packaged software are Microsoft Word, Microsoft Excel, Microsoft Access and so on.
- Tailored software or customized software is the software developed to meet the specific requirement of a particular organization, institution or person. Industrial automation software, business software, payroll software of a company, banking software designed especially for a bank, result processing system for SLC exam etc are examples of some customized software.
- WordProcessing software allows users to create, edit and format documents.
- Database software allows uses to store and retrieve huge amount of data from database quickly.
- Spreadsheet software allows uses to perform complex calculation on a large electronic sheet.
- Multimedia software allows uses to create, edit and play audio, video media.
- Presentation software allows users to create and present information in the form of display slides.
- Image editing software allows uses to create and manipulate images, photographs and other graphics objects.


The British monopoly on the salt trade in India dictated that the sale or production of salt by anyone but the British government was a criminal offense punishable by law. Salt was readily accessible to coastal area dwellers, but instead of being allowed to collect and use it themselves for free, they were instead forced to purchase it from the colonial government.
In other words, the British government owned the right to produce and sell salt in India.
And another page says:
On April 5, 1930 Gandhi and his satyagrahis reached the coast. After prayers were offered, Gandhi spoke to the large crowd. He picked up a tiny lump of salt, breaking the law. Within moments, the satyagrahis followed Gandhi's passive defiance, picking up salt everywhere along the coast. A month later, Gandhi was arrested and thrown into prison, already full with fellow protesters.
Was Gandhi stealing salt from the British government, or was he simply breaking the law which gave the British the exclusive right to produce salt?
Since Gandhi wasn't actually taking the salt away from the British, and the ocean contained a practically infinite supply of salt (so it can't be claimed that he was taking it from anyone else), I'd argue that he was not stealing anything.
Did Gandhi steal the legal "right" to produce salt? Not really. A right has no substance or physical reality, so it is difficult to outright steal one (you could perhaps trick someone into signing a contract transferring the right, but clearly that's not the case here).
Gandhi's actions DID decrease the value of the British right to produce salt, but many actions could have that effect. For example, he could have convinced the people of India to switch to a lower salt diet, thereby decreasing the demand for salt and the value of the British monopoly. I don't think that anyone would call that stealing.
In fact, I've never seen anyone claim that Gandhi was a thief. It seems like a somewhat silly argument.
So what's my point? Owning a "right", which is a form of "Imaginary Property", is not the same as owning real property. If someone violates your exclusive rights, they may be breaking the law, but they are not stealing. To claim otherwise is silly and dishonest.
Update: Some people have interpreted this post as meaning that I'm opposed to Imaginary Property, or that infringing on other's legal rights is ok. That is not the case at all -- IP can serve an important and beneficial role in society. My only point is that Imaginary Property is not the same as Real Property, and that infringing on someone's legal rights isn't the same as theft. Pretending that they are the same has caused a lot of unnecessary trouble.


As a youngster in the early 2000s, I had scored a copy of Unreal Tournament. I played it for hours, feeling superior to everyone I beat. However, I soon found out that I wasn’t even connected to an Internet server.
I had been playing against AI game bots.
Needless to say, I was fooled. The AI bots’ behaviors in ‘online’ games of the Unreal Tournament were so human-like. So what’s the difference between bot and humans in games? Let’s break it down.
What Are Video Game Bots?
Quite simply, video game bots are instances of artificial intelligence (AI) that play a game instead of a player. Game bots are present in nearly every multiplayer game, from Halo to MMORPGs.
Game bots perform various tasks, everything from acting as the player would or NPCs doing farm work. Artificial intelligence has come a long way from the days of Pong.
There are various types of game bots as well.
Types of Bots
Let’s outline three different types of bots.
Static Game Bots
Static game bots need a lot of assistance to act appropriately. These game bots are ones that have a relatively small agency to move on their own accord. They usually exist to serve out a linear function, like follow directions or trade with the player at a shop.
Dynamic Game Bots
Dynamic game bots can partake in learning the layouts of levels, learning new strategies, and more. The behavior of these bots can be found most in a popular game like Counter-Strike.
There are even game bots that engage in both static and dynamic behaviors. Counter-Strike, for example, uses both static waypoints and dynamic actions and behaviors in online games to act more realistic.
There are bots that both take part in completing repetitive tasks associated with smaller game details and undertake quest goals.
Bot vs Non-Player Character
There may be a small misconception between a game bot vs. an NPC. NPCs, non-player characters, never play the game. Bots, on the other hand, are modeled off of the player to create actual gameplay. NPCs like those in MMORPGs never aim to mimic the player’s behavior in online play.
Think of NPCs more like set pieces. They are there to populate the game world but not overtly interact with its elements.
Game bots aren’t the only bots you interact with. Think of when you accessed an app or a website and started chatting with someone. That’s a bot programmed to perform specific tasks through the power of artificial intelligence.
Many bots in that position use learned communication through analyzed data and information through things like machine learning.
How to Create Bots
You can actually create your own bots for games, online activity, and more. But how?
There are a few things to consider before creating a bot. It will most likely come down to knowing a programming language like Python or C++.
Along with programming expertise, developers need to create macros that serve as a general map of behavior for the game bots. These allow you to program bots to do basically anything you want them to. Whether it’s a repetitive task, or something more complex, macros will be your lifeline here.
However, one obstacle that may be a little hairy is skirting around a game’s bot detection system. Since we want a bot to act identically to a human player, you need to be meticulous with your programming.
Your method, process, and approach depending on what you want your bot to do. Do you want them to act in static ways, dependent on your lines of code? Or do you want them to follow you around and assist as a cooperative player would?
It’s a bit controversial to use bots in games to your own ends. Collecting resources in different areas can be considered cheating, and many games have bot detection and algorithms designed to sniff out suspicious behavior.
While many of the bot’s behavior rests on your coding skills and overall goals, you also need to be careful. For example, if you were to run into server-side detection, you could get banned from a game.
The Future of Bots
Game bots and artificial intelligence are only getting more impressive. Through things like a machine and deep learning, game bots will be nearly indistinguishable from real players. They allow for players short on fellow players to still experience the game. The chances are that you won’t even want human teammates in the future.
The trajectory of deep learning regarding AI is impressive, as exhibited through Tesla’s self-driving cars and more.
Either way, they’re only going to engage in more effective communication, complete more complex tasks, and maybe even fool everyone.


This school year, Seventh Generation is sharing tips from best-selling author and pediatrician, Dr. Alan Greene, to help parents protect their child’s health during back-to-school season. Dr. Greene suggests taking the following precautions:
Optimize the immune system
:: Reap the benefits of probiotics like those found in yogurt. A recent study showed that children who received enough probiotics daily throughout the cold and flu season had a significant reduction in the number of illnesses they had and, when they did get sick, the symptoms were both milder and didn’t last as long.
:: Be sure your child is getting plenty of vitamin D from the sun, from food, or from a supplement.
:: Build a strong foundation. Good food, good sleep, and good physical activity all help the immune system to flourish.
Be wise about reducing unnecessary exposure to harmful germs
:: Teach children the key times to clean their hands in the classroom. The most important times include after sneezing, coughing or using the restroom, upon leaving “high-risk” places (recess, naptime, play stations) and before meals or snacks.
:: Stress the importance of not touching their eyes, nose or mouth. Germs are often spread when a person touches something that is contaminated with germs and then touches his or her eyes, nose, or mouth.
:: Demonstrate to your children how to cover their mouth and nose for every cough and sneeze. This simple maneuver has spectacular results in decreasing the spread of viruses and bacteria floating about the room, waiting to be inhaled.
Seventh Generation, through MyBlogSpark, is giving one Frugal Living NW reader a Seventh Generation “Back to School” kit, which includes:
- a Seventh Generation backpack
- two canisters of Seventh Generation disinfecting wipes — kills 99.99% of germs naturally using the active ingredient thyme, a component of thyme oil which is derived from the herb thyme
- Seventh Generation disinfecting multi-surface spray cleaner
- Seventh Generation facial tissue
- Seventh Generation paper towels
You have four opportunities to enter this giveaway (be sure to leave a separate comment for each entry):
:: Leave a comment.
:: “Like” Frugal Living NW on Facebook. Leave an additional comment indicating you like us. DO NOT leave your comment on the Facebook page.
:: Follow Frugal Living NW on Twitter. Leave an additional comment indicating you’re a Twitter follower.
If you are reading this post via email and wish to enter, you must comment on the actual blog. DO NOT reply to this digest email to enter the giveaway. An email reply is not an acceptable entry.
Comments will close and four winners randomly selected Friday, September 10th at Noon.
Disclosure: Seventh Generation, through MyBlogSpark, provided me with the information contained in this post, the giveaway items and a Back to School kit for my family.
This post may contain affiliate links. See the disclosure policy for more information.


Four simple rules that enable students to control the sounds that single vowels make in syllables
A whole day workshop for teachers on Boosting the Inclusive Quality of your Lessons
An evening session for parents of struggling learners
The power of "hands on spelling"
TES SEN Show with Neil MacKay presenting 2 workshops.
The day will include:
-Morning session: keynote address by Neil Mackay
-Afternoon workshops (Workshop A on the use of Clicker 7 to support pupils with literacy difficulties, Workshop B with Neil Mackay)
Available resources for my upcoming work with Ayr Schools.
The theory of learning styles is bad science.
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