CZ:Featured article/Current: Difference between revisions

From Citizendium
Jump to navigation Jump to search
imported>Anthony.Sebastian
imported>Chunbum Park
No edit summary
Line 1: Line 1:
== '''[[Global warming]]''' ==
== '''[[Warfarin]]''' ==
''by [[User:Gareth Leng|Gareth Leng]], [[User:Raymond Arritt|Raymond Arritt]], [[User:Robert Badgett|Robert Badgett]], [[User:Nereo Preto|Nereo Preto]], [[User:Anthony.Sebastian|Anthony.Sebastian]], and [[User:Benjamin Seghers|Benjamin Seghers]] <small>(and [[User:Milton Beychok|Milton Beychok]], [[User:David Finn|David Finn]], [[User:Greg Harris|Greg Harris]], [[User:Ed Poor|Ed Poor]], [[User:Larry Sanger|Larry Sanger]], [[User:John Stephenson|John Stephenson]] and [[User:Paul Wormer|Paul Wormer]])</small>''
''by [[User:Robert Badgett|Robert Badgett]], [[User:David E. Volk|David E. Volk]], and [[User:Chris Day|Chris Day]] <small>(and [[User:Caesar Schinas|Caesar Schinas]])</small>''
----
----
[[Image:105582main GlobalWarming 2060 lg.jpg|right|thumb|Annual average global warming by the year 2060 simulated and plotted as color differences using EdGCM|250px]] 
{{Image|Warfarin structure.jpg|right|200px|Structure of Warfarin.}}


'''[[Global warming]]''' is the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation.  There is strong evidence that significant global warming is occurring; this evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in recent decades is attributable to human activity, particularly the burning of fossil fuels and deforestation.  
'''[[Warfarin]]''' (IUPAC name
4-hydroxy-3-(3-oxo-1-phenylbutyl)-2H-chromen-2-one), also widely called coumadin, is a an anticoagulant medication used prophylactically to suppress the formation of embolism and thrombosis from conditions such as atrial fibrillation, deep venous thrombosis, and pulmonary embolism.


Global average air temperature near the Earth's surface rose by 0.74 ± 0.18&nbsp;°[[Celsius|C]] (1.33 ± 0.32&nbsp;°F) from 1906 to 2005. The prevailing scientific view, <ref name = Doran>See [http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf Doran (2009)] 'Examining the Scientific Consensus
Originally designed to be a rat poison, warfarin works as an anticoagulant by suppressing the enzyme epoxide reductase in the liver, thereby suppressing the formation of the reduced form of vitamin K epoxide, which is needed for the synthesis of many coagulation factors. As a drug, it is often sold as the sodium salt of warfarin.
on Climate Change' for information on a poll of research-active climate scientists, other researchers and the public regarding the scientific consensus on global warming ''Eos'' 90: 21-2</ref> as represented by the science academies of the major industrialized nations<ref name = "academies">[http://nationalacademies.org/onpi/06072005.pdf Joint science academies’ statement: Global response to climate change]
*"There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in recent decades can be attributed to human activities (IPCC 2001). This warming has already led to changes in the Earth's climate."</ref>
and the ''[http://www.ipcc.ch/ Intergovernmental Panel on Climate Change]'',<ref name=grida7>{{cite web | url=http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spm.html|title=Summary for Policymakers|work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change|date=2007}}
*"Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations...Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns" </ref> it is very likely that most of the temperature increase since the mid-20th century has been caused by increases in atmospheric greenhouse gas concentrations produced by human activity. Climate models predict that average global surface temperatures will increase by a further 1.1 to 6.4 °C (2.0 to 11.5 °F) by the end of the century, relative to 1980–1999.<ref name=grida7/> The range of values reflects differing assumptions of future greenhouse gas emissions and results of models that differ in their sensitivity to increases in greenhouse gases.<ref name=grida7/>


Scientists have not yet quantitatively assessed the potential self-accelerating effects of global-warming itself, either on threshold or rate.  Melting of permafrost, for example, causes increased production and atmospheric release of such newly produced as well as anciently stored methane gas, which  “….packs a far greater warming punch than [carbon dioxide] (CO<sub>2</sub>),”<ref name=walker2007>Walker G (2007) [http://dx.doi.org/10.1038/446718a Climate Change 2007: A world melting from the top down] ''Nature'' 446:718-21</ref> possibly as much as 25 times that of CO<sub>2</sub> per unit mass.<ref name=simpson2009>Simpson (2009) [http://www.ScientificAmerican.com/Earth3 "The Peril Below the Ice"] ''Scientific American Earth 3.0'' pp 30-7</ref>  
===Discovery===
The dangers of feeding livestock spoiled sweet clover hay were known in the 1920’s<ref>Wardrop D, Keeling D (2008) The story of the discovery of heparin and warfarin ''Brit J Haematol'' 141:757-63</ref> and scientists at the University of Wisconsin-Madison were spearheading the problem on multiple fronts. R.A. Brink and W.K. Smith were attempting to breed a new variety of clover that was free of the toxic effect and Karl Paul Link's laboratory was attempting to isolate the killer compound. Farmers were already hurting due to the Great Depression and despite knowing they should not feed their livestock such hay, they could not afford to buy uncontaminated supplies. This disease that was affecting many livestock throughout the US became known as "sweet clover disease".<ref>Duxbury BM, Poller L (2001) The oral anticoagulant saga: past, present, and future ''Clin Appl Thrombosis/Hemostasis'' 7:269–75 PMID 11697707</ref>


An increase in global temperatures will cause the sea level to rise, glaciers to retreat, sea ice to melt, and changes in the amount, geographical distribution and seasonal pattern of precipitation. There may also be changes in the frequency and intensity of extreme weather events. These  will have many practical consequences, including changes in agricultural yields and impacts on human health.<ref>[http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch19s19-3-6.html Schneider ''et al.'' (2007)]. [http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch19.html Assessing key vulnerabilities and the risk from climate change]. In Parry ML ''et al.'' (eds) ''[http://www.ipcc.ch/publications_and_data/ar4/wg2/en/contents.html Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change]'' Cambridge University Press pp 779-810
''[[Warfarin|.... (read more)]]''
*"There is new and stronger evidence of observed impacts of climate change on unique and vulnerable systems (such as polar and high-mountain communities and ecosystems), with increasing levels of adverse impacts as temperatures increase (very high confidence).
*There is new evidence that observed climate change is likely to have already increased the risk of certain extreme events such as heatwaves, and it is more likely than not that warming has contributed to the intensification of some tropical cyclones, with increasing levels of adverse impacts as temperatures increase (very high confidence).
*The distribution of impacts and vulnerabilities is still considered to be uneven, and low-latitude, less-developed areas are generally at greatest risk due to both higher sensitivity and lower adaptive capacity; but there is new evidence that vulnerability to climate change is also highly variable within countries, including developed countries." </ref> Scientific uncertainties include the extent of climate change expected in the future, and how changes will vary around the globe. There is political and public debate about what action should be taken to reduce future warming or to adapt to its consequences. The Kyoto Protocol, an international agreement aimed at reducing greenhouse gas emissions, was adopted by 169 nations.
''[[Global warming|.... (read more)]]''


{| class="wikitable collapsible collapsed" style="width: 90%; float: center; margin: 0.5em 1em 0.8em 0px;"
{| class="wikitable collapsible collapsed" style="width: 90%; float: center; margin: 0.5em 1em 0.8em 0px;"

Revision as of 04:37, 2 December 2011

Warfarin

by Robert Badgett, David E. Volk, and Chris Day (and Caesar Schinas)


(CC) Image: David E. Volk
Structure of Warfarin.

Warfarin (IUPAC name 4-hydroxy-3-(3-oxo-1-phenylbutyl)-2H-chromen-2-one), also widely called coumadin, is a an anticoagulant medication used prophylactically to suppress the formation of embolism and thrombosis from conditions such as atrial fibrillation, deep venous thrombosis, and pulmonary embolism.

Originally designed to be a rat poison, warfarin works as an anticoagulant by suppressing the enzyme epoxide reductase in the liver, thereby suppressing the formation of the reduced form of vitamin K epoxide, which is needed for the synthesis of many coagulation factors. As a drug, it is often sold as the sodium salt of warfarin.

Discovery

The dangers of feeding livestock spoiled sweet clover hay were known in the 1920’s[1] and scientists at the University of Wisconsin-Madison were spearheading the problem on multiple fronts. R.A. Brink and W.K. Smith were attempting to breed a new variety of clover that was free of the toxic effect and Karl Paul Link's laboratory was attempting to isolate the killer compound. Farmers were already hurting due to the Great Depression and despite knowing they should not feed their livestock such hay, they could not afford to buy uncontaminated supplies. This disease that was affecting many livestock throughout the US became known as "sweet clover disease".[2]

.... (read more)