Welcome to Citizendium: Difference between revisions

From Citizendium
Jump to navigation Jump to search
imported>John Dvorak
m (fixed main page redirect)
imported>Todd Coles
(Article/New Draft of the Week update)
Line 77: Line 77:
|}
|}
=== Article of the Week <font size=1>[ [[CZ:Article of the Week|about]] ]</font> ===
=== Article of the Week <font size=1>[ [[CZ:Article of the Week|about]] ]</font> ===
[[Image:Civil war map.png|left|thumb|300px|{{#ifexist:Template:Civil war map.png/credit|{{Civil war map.png/credit}}<br/>|}}Map depicting slave and free states during the war.]]  
[[Image:Tapping_coherer.jpg|thumb|left|200px|Classic "tapping" form of a glass tube "filings coherer".]]A '''[[coherer]]''' is a type of [[radio]] detector, popular in the earliest days of radio development, beginning around 1890. Coherer receivers, used in conjunction with [[spark-gap]] transmitters, were the first devices to make radio communication practical. However, although hailed at the time as a "marvelous electric eye", their relative insensitivity and unreliability led to their replacement by more sophisticated detectors, so the device that helped create a communications revolution disappeared from commercial use by around 1905.
The '''[[U.S. Civil War]]''' in the U.S. 1861-65, saw the Union (North), led by [[Abraham Lincoln]] and General [[Ulysses S. Grant]] defeat the breakaway Confederacy (South) led by [[Jefferson Davis]] and General [[Robert E. Lee]] and end slavery. Reunion was accomplished by a difficult period of [[Reconstruction]], 1865-1877, in which the freed slaves were given the right to vote.


The war was between the United States (the "Union") and eleven Southern states that declared they had a right to [[secession]] and formed the [[Confederate States of America]]. Led by President [[Jefferson Davis]], the South proclaimed that "Cotton is King", meaning it was so powerful an economic force that European powers would help them win. The Union, led by Lincoln and the [[U.S. Republican Party, history|Republican Party]], rejected any right of secession. They said they would not interfere with slavery inside the South, but would put it on the path to eventual extinction by preventing its expansion. Fighting began on April 12, 1861, when Confederate forces attacked a U.S. military installation at Fort Sumter in Charleston, South Carolina. Lincoln called for an invasion force to recapture the fort, and four more states, rejecting coercion, joined the Confederacy to make 11 in all.
The defining characteristic of a coherer detector is a "light-contact" segment that is normally a poor electrical conductor, but which undergoes a sudden change in conductivity &mdash; usually a marked increase &mdash; in response to increased voltage, including that induced by a received radio signal. A limitation of coherers is that they cannot be used for full audio reception of radio signals, and are limited to receiving simple on-off transmissions, such as the telegraphic dots-and-dashes of Morse code produced by the intermittent keying of a transmitter.
<font size=1>[[U.S. Civil War|['''more...''']]]</font>
<font size=1>[[Coherer|['''more...''']]]</font>


=== New Draft of the Week <font size=1>[ [[CZ:New Draft of the Week|about]] ]</font> ===
=== New Draft of the Week <font size=1>[ [[CZ:New Draft of the Week|about]] ]</font> ===
'''[[Naval guns]]''' came into general use in the West in the 14th century. They replaced the tactics or ramming or boarding, and became the main naval weapon when it was realized they could sink an enemy ship some yards away, regardless of the wind.  From 1500 to 1941 all the major fleets were built around platforms that could shoot bigger and more accurate guns. The aircraft carrier proved itself at the [[Battle of Pearl Harbor]] in 1941, ending the era. Naval guns are now used primarily in defense against small boat or missile attacks.  
[[Image:Whale-meat-dish.jpg|right|thumb|200px|{{#ifexist:Template:Whale-meat-dish.jpg/credit|{{Whale-meat-dish.jpg/credit}}<br/>|}}Whale meat is considered a delicacy in [[Japan]]. Here, the meat has been sliced into a strip of 'whale bacon'.]]
<font size=1>
'''[[Whale meat]]''' refers to the edible flesh of various [[species]] of [[whale]]. It can be prepared and eaten in various ways, and for example forms one part of traditional [[Japan]]ese cuisine (鯨肉 ''gei niku'' 'whale meat'). Servings also appear on menus in [[Norway]] and [[Iceland]], where whales are also [[whaling|hunted]], and also some [[Aboriginal]] communities take whales for their [[meat]].
[[Naval guns|['''more...''']]]</font>
 
In recent years, however, concerns have been raised about the levels of [[pollution|pollutants]] in samples of whale meat,<ref>''[[New Scientist]]'': '[http://www.newscientist.com/article/dn2362-extreme-mercury-levels-revealed-in-whalemeat-.html Extreme mercury levels revealed in whalemeat]'. 6th June 2002.</ref> and many people around the world object to the hunting and eating of whales and [[dolphin]]s. In turn, pro-whaling representatives have argued that eating whale meat is more [[global warming|environmentally friendly]] than consuming meat raised from [[cattle]].
<font size=1>[[Whale meat|['''more...''']]]</font>
|}
|}
<!-- <s>Strike-through text</s> -->
<!-- <s>Strike-through text</s> -->

Revision as of 19:01, 25 March 2008

Logo400grbeta small.png
Natural Sciences       Social Sciences       Humanities
Arts       Applied Arts and
Sciences
      
Recreation

A wiki encyclopedia project—and more!

  • We aim at credibility, not just quantity.
  • Open to public participation—gently guided by experts.
    (What a concept!)
  • We write under our real names and are both collegial and congenial.
  • We're [[:Category:CZ Live|Template:Articles number articles]] (plus!) strong.
  • Eduzendium participants write for academic credit.

Write for the Citizendium

Learn about us

Support us

 

(CC) Photo: Tanya Puntti
Each sentence you add is another drop in an expanding sea of words.

Some of our finest [ about ]

Approved.png
Share your knowledge. It's a way to achieve immortality.
–Often attributed to the Dalai Lama

Article of the Week [ about ]

Classic "tapping" form of a glass tube "filings coherer".
A coherer is a type of radio detector, popular in the earliest days of radio development, beginning around 1890. Coherer receivers, used in conjunction with spark-gap transmitters, were the first devices to make radio communication practical. However, although hailed at the time as a "marvelous electric eye", their relative insensitivity and unreliability led to their replacement by more sophisticated detectors, so the device that helped create a communications revolution disappeared from commercial use by around 1905.

The defining characteristic of a coherer detector is a "light-contact" segment that is normally a poor electrical conductor, but which undergoes a sudden change in conductivity — usually a marked increase — in response to increased voltage, including that induced by a received radio signal. A limitation of coherers is that they cannot be used for full audio reception of radio signals, and are limited to receiving simple on-off transmissions, such as the telegraphic dots-and-dashes of Morse code produced by the intermittent keying of a transmitter. [more...]

New Draft of the Week [ about ]

(CC) Photo: Franklin Bynum
Whale meat is considered a delicacy in Japan. Here, the meat has been sliced into a strip of 'whale bacon'.

Whale meat refers to the edible flesh of various species of whale. It can be prepared and eaten in various ways, and for example forms one part of traditional Japanese cuisine (鯨肉 gei niku 'whale meat'). Servings also appear on menus in Norway and Iceland, where whales are also hunted, and also some Aboriginal communities take whales for their meat.

In recent years, however, concerns have been raised about the levels of pollutants in samples of whale meat,[1] and many people around the world object to the hunting and eating of whales and dolphins. In turn, pro-whaling representatives have argued that eating whale meat is more environmentally friendly than consuming meat raised from cattle. [more...]