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Talk:Blood transfusion

Confusing Blood Transfusion Safety Section
I am confused as to whether all the bullets listed under Blood Transfusion Safety sections are conditions that the a recipient may or may NOT get as a result of a transfusion. Is this section saying that donated blood is screened for all these conditions, or is it saying it that the blood supply is NOT screened for these? (I don't know this topic very well).

Also, maybe this section should be merged into the Risks section? 75.6.228.54 05:54, 21 October 2007 (UTC)

Mixed Comments
Please consider addinf a section on or cross-reference to the religious concerns and objections to transfusion.

I don't see an article on, or discussion here, of blood exchanges, the procedure in which we replace a patient's blood (at a logarithmic return on new blood). Should we add content to this article to cover it? If so, should we change the name of the article to "Blood transfusion and exchange", or provide a redirect from "Blood exchange"? (New contributor to wikipedia.)--Ojophoyimbo 2006-01-03@21h44m UTC

Needs references to cover the content, added tag.--FloNight 14:08, 27 November 2005 (UTC)
 * From page with unreferenced tag: This template should only be placed on a talk page or at the bottom of an article, preferably in the empty 'References' section.--FloNight 18:03, 27 November 2005 (UTC)

 * If you put it here, hardly anyone will see it. Just visit Category:Articles lacking sources and you'll see that there are hardly any talk pages listed there. - Karl Stas 22:09, 27 November 2005 (UTC)

"The time required to donate blood is different from the Blood Donation article. Please select a time in common, I would recommend thirty minutes" --JoshNahum 15:12, 4 Jul 2005 (UTC)

"7th century"? Is that a typo for "17th century"?

 * I wondered the same thing when I read that line. --AaronW 23:34, 17 Jun 2004 (UTC)

 * It certainly was! - Nunh-huh 23:36, 17 Jun 2004 (UTC)

Took "probably" out of this sentence, since "it's likely" already says that. "it's likely that the transfusion probably caused his death."

donors with high risk sexual behaviour
Can we have a definition of this? Or rather, examples of what different countries/medical agencies define as high risk. Is it prostitution, promiscuity, homosexuality, ...? --Joy [shallot]   11:56, 12 August 2005 (UTC)

Procedure
Why does the procedure section only cover the donation of the blood and not the actual operation in which a patient recieves it?

 * Because that is more straightforward. I'll see if I can write a line or two. JFW | T@lk  23:41, 15 November 2005 (UTC)

 * At the risk of publishing original research I could not find a reference for giving Lasix with blood in patients with heart failure. JFW | T@lk  23:55, 15 November 2005 (UTC)

the procedure section states that transfusions normally require four hours. i am trying to find a reference for this statement, which would explain why four hours is required and why it may be dangerous to infuse multiple units within four or less hours. any suggestions are appreciated. thanks.

 * There are a couple reasons why transfusions are usually done one at a time and slowly. First, if there are multiple units hung and the recipient has a reaction, it's impossible to tell which of the units caused it.  Secondly, if a hemolytic transfusion reaction occurs it is best to have a minimal amount actually transfused.  Third, circulatory overload (too much fluid) can cause problems, and a slow transfusion allows the body to move excess fluid to interstitial spaces and out of circulation.  Lastly, blood for transfusion, especially type O negative red cells and platelets of any type, is often in short supply, so generally only the smallest amount needed is used.  If the patient is stable on less, further units are generally not ordered.  In trauma situations or other critical need scenarios, these concerns are generally waived based on the actual needs of the patient.

150.148.0.27 18:36, 25 October 2007 (UTC)

"Type of organ donation"
The only source for this that I can find so far, is in a defense of transfusions by for Witnesses by the AJRWB: http://www.ajwrb.org/science/meal.shtml. As such, this may be a subtle attempt at making a religious statement as opposed to impartial, unbiased, pure knowledge. If anyone can find a non-religious medical source for this, it would be appreciated. -- Avi 19:40, 22 February 2006 (UTC)

 * The article attributes that claim to 'cardiovascular surgeon Denton Cooley'. I don't know what Cooley's personal beliefs are, but he looks to have good medical credentials. I couldn't verify that particular quote, and I'm always wary of short quotes out of context, but I wouldn't be terribly surprised if a medical professional said such a thing.

 * That said, supposing for the sake of argument that he and a dozen other doctors have said such a thing, the way a fact is presented can still make it POV. I don't see that this factoid is particularly useful or notable in any but this particular religious context. If it's going to be brought up, that context should be made clear. It would be appropriate in a section on the JWs' stance on transfusions (maybe this article should have such a section?) but not context-free in the intro paragraph of the article. --Calair 23:16, 22 February 2006 (UTC)

the procedure section states that blood transfusions normally take four hours. i am trying to find a reference for this statement, which would explain why four hours is needed and why it may be dangerous to administer multiple units within four or less hours. does anyone have a suggestion? thanks

Complications of transfusion
Can an informed persion exand this area? Snowman 10:47, 27 March 2006 (UTC)
 * OK, I've done my best. Thoughts? MastCell 21:51, 10 August 2006 (UTC)

Photopherisis
I am assuming that photophoresis (sic) is distinct from photopheresis which is to do with blood transfusion and apherisis. Am I right? Cutler 09:12, 2 June 2006 (UTC)

Tranfusion-related immunosuppression
Added a request for citation on the statement about transfusions suppressing the immune system and leading to increased complications after surgery. I know there have been a few papers describing an increased risk of mortality with more liberal transfusion strategies, and a citation would be useful - I'll look into it as well. Will also expand the "Risks" category with some hard numbers once I have a chance. I've also added a section listing the specific infectious agents for which donated blood is screened in the U.S. (with citation). MastCell 18:08, 10 August 2006 (UTC)

 * This is probably a good one: --WS 23:37, 11 August 2006 (UTC)

Talking about risks, this is also interesting: difference in risks and indications in poor and rich countries. --WS 23:54, 11 August 2006 (UTC)

 * Those are both good references... feel free to add a section on transfusion-related immune suppression, or I will get around to it sooner or later. The question is always - did they get sick because they got transfused, or were the transfused pts sicker to start with (hence the transfusions)? I assume the reference addresses that issue; I'll take a look. MastCell 00:31, 12 August 2006 (UTC)

Related topics
I've managed to swell the page to an ungodly size. Thoughts on splitting off "History of blood transfusion" and "Exchange transfusion" (which is not yet covered on this page)? MastCell 22:45, 11 August 2006 (UTC)
 * Exchange transfusion is briefly mentioned on HDN and Rh disease pages. Snowman 09:42, 12 August 2006 (UTC)

In the section titled leukoreduction it says that stray white blood cells are removed from the donated blood.Does this mean that all white blood cells in the donor's blood are removed or just certain white blood cells. If stray white blood cells stand for only a certain type of white blood cells could somebody please clarify this by explaining the type of white blood cells that should be removed. If all white blood cells are removed from the donor's blood could somebody please remove the term "stray". —The preceding unsigned comment was added by 88.110.207.144 (talk • contribs).

Indications
A section about the indications for blood transfusion is still missing. could be of some help if someone wants to write it. --WS 23:44, 11 August 2006 (UTC)

Merge ?
Why not merge Blood transfusion and Transfusion reactions? Snowman 08:35, 14 August 2006 (UTC)
 * Since there's not much difference right now, you certainly could. However, I can imagine a transfusion reaction page which is much more than the current list, including sections on each individual reaction, etc. They are different enough topics that each could more than stand on its own. If you'd like, you can put a merge template up on this and the reaction page and probably get more comments! InvictaHOG 11:22, 14 August 2006 (UTC)
 * Yes, the two pages could become very different with more development; however, there is a lot of duplication at the present time. No merged needed.  Snowman 12:07, 14 August 2006 (UTC)
 * After I edited the blood transfusion page, there ended up being more info on transfusion reaction there than on the "Transfusion reaction" page, so I copied most of the info and expanded it slightly. Perhaps this was a mistake. Agree that the transfusion reaction page could definitely be expanded and reorganized, or the info could be removed from the "Blood transfusion" page and replaced with a "main article" link. Probably better to keep 2 separate pages since they are both fairly involved subjects; those are my 2 cents. MastCell 15:46, 14 August 2006 (UTC)

I am attempting to merge all subsections (ie transfusion reaction, crossmatch, etc that are stub-like) into this page to make flow better

Shaolin md (talk) 21:17, 16 March 2011 (UTC)

Religious Objections
Jehovah's Witnesses believe that the Bible prohibits the consumption, storage and transfusion of blood including in cases of emergency. This has been their view since 1945. Over the years their stance on blood has been a source of controversy, as members have died due to loss of blood.

Jehovah's Witnesses believe that in the Bible blood is sacred to God representing life thus it must not be eaten but pour out (figuratively giving it back to God). They also state that blood was reserved for only one special use, the atonement for sins, leading up to Jesus' shed blood, thus when a Christian abstains from blood, he or she is in effect expressing faith that "only the shed blood of Jesus Christ can truly redeem him and save his life.-Ephesians 1:7" Therefore, they believe that when the New Testament says to “keep abstaining from ...blood” [Acts, Ch. 15, Verse 29] it means that Christians should, 'not take blood into their bodies at all.' —The preceding unsigned comment was added by Johanneum (talk • contribs).

 * Perhaps the section could be on "Objections to blood transfusion" (in keeping with the statement about NoBlood) with the recognition that the majority of objections are religiously based. Since you are clearly familiar with the rationale behind JW objections to blood transfusions, why don't you go ahead and start a section on it. The more citations the better, especially when broadly describing a religion's beliefs, as it will make the article more robust and less POV-sounding. MastCell 17:23, 10 October 2006 (UTC)

Sounds good. I have rewrote the first par.to what is below. It is a start for now. Jehovah's Witnesses do not accept tranfusions of whole blood or its four major components namely, red blood cells, white blood cells, platelets (thrombocytes), and whole plasma. They also do not donate or store their own blood for transfusion.Johanneum 12:26, 13 October 2006 (UTC)

National scandals and recovery
Maybe we should include a sentence or two about the Canadian "tainted blood scandal" on this page. In the 1980s, the Canadian Red Cross was responsible for blood donations. However, their screening methods were limited and they were importing blood collected from prisons in the US. This led to thousands of Canadian citizens being infected by HIV and Hepatitis C. After a long enquiry, the Canadian Red Cross was no longer responsible for collecting and testing blood; two newly created agencies took over: the Canadian Blood Services (for most of Canada) and Héma-Québec (in the Quebec province). The two agencies share their knowledge, use similar technologies, and invest actively in R&D for developing new screening technologies. Héma-Québec is currently testing a new screening test for CjD; the test should become fully operational in 2010 and the "donation ban" for people who have stayed in the UK will be lifted. See Royal Commission of Inquiry on the Blood System in Canada for some background info on the scandal. -- Hugo Dufort 01:51, 28 November 2006 (UTC)

A "tainted blood scandal" occurred in Japan too. However, I am not familiar with the incident. -- Hugo Dufort 01:56, 28 November 2006 (UTC)

 * This probably needs its own page, because HIV isn't the only bug in question and this particular scandal hit quite a few countries. Japan, I believe, is wrestling with a similar problem for Hepatitis C screening failures as of 2008.Somedumbyankee (talk) 06:26, 13 March 2008 (UTC)

Chagas/Leichmania in the blood system
Can some mention be made of the new testing policies being put in place for Trypanosoma and Leishmania? I know there were several Chagas infections in the past decade which have been traced back to transfusions and transplants.Rusty 22:01, 18 March 2007 (UTC)

 * I can only speak for US policy, but the official guidance and typical practice is to defer donors who have been in areas endemic for Leishmaniasis for a year. Since Iraq is a main area of concern this is largely transparent since it's also a malarial risk area and the donors would be deferred for a year anyway (though plasmapheresis donors are affected since malaria is irrelevant to acellular components).  A screening test for T. cruzi (Chagas) has been implemented in many US blood centers, but isn't required.Somedumbyankee (talk) 06:26, 13 March 2008 (UTC)

Intravenous route
It's not strictl true that a transfusion can only be carried out via the intravenous route. Endosteal transfusion (i.e. into the medullary cavity of bone) is theoretically possible, and peritoneal transfusion is occasionally practiced in neonates of some animal species. The water and plasma salts are absorbed easily across the peritoneum by diffusion; the protein and even the cellular fraction by active uptake (pinocytosis). 86.133.243.110 15:10, 15 June 2007 (UTC)

Stored blood loses Nitric Oxide?
http://www.economist.com/science/displaystory.cfm?story_id=9941992 Any idea how to add the findings of that study to the article? --204.4.131.140 09:05, 12 October 2007 (UTC)
 * Here's a second source if anyone needs it.

http://www.time.com/time/magazine/article/0,9171,1670523,00.html Ixistant 18:37, 3 November 2007 (UTC)

 * This is specific to packed Red Blood Cells (maybe also Whole Blood) and might be better explained on the specific pages. This page is very busy as it is.  Not sure if NO metabolism has its own page.  Definitely deserves a mention or a link, though.Somedumbyankee (talk) 06:26, 13 March 2008 (UTC)

Wikipedia Scaremongering Strikes Again
Just reading your wonderfull article, very detailed, however, once again wikipedia has demonstrated the tactic of scaremongering in terms of risk assessment for medical conditions. Specifically on the transferred diseases thru blood transfusion section, noone happens to mention that thanks to screening, the chance of picking up a transmitte disease through blood is about 0.25%. Ask your local doctor or hospital, blood is screened so thoroughly that only about 15% of donated blood is given final approval for transmission to another patient. - 203.51.43.121 (talk) 00:30, 2 December 2009 (UTC)

 * Uh... where are you getting those numbers? The risk of transfusion-transmitted infection (TTI) is about the same risk of getting struck by lightning in most developed countries.  There are millions of transfusions each year in the US, and the number of reported transfusion-associated infections is in the tens, many of which are unlikely to be actual TTI's, so 0.25 is way too high (maybe 0.0000025%).  The 15% figure is also bizarre.  Of people that volunteer to donate (which is a lot less than 15% of the population), most (~85-90%) donation attempts result in transfusable components.  The most common reason that an attempt fails is that the donor does not have a high enough iron level, disease-related failed donations account for maybe 1% of failed donation attempts, mostly due to near-paranoid exclusion of any group that might be at high risk rather than test results.  Again, these are US numbers, and I'd assume that most developed countries are similar.  In Zimbabwe, maybe not.  SDY (talk) 16:26, 3 December 2009 (UTC)

Studies related to efficacy of modern blood use
There is information related to the history of the use of blood transfusion in the article, but little related to modern research of blood transfusion practice. Of course the individual studies them self would be too numerous to mention. Perhaps some of the more recent ones could be mentioned. There are numerous news articles related to an expert panel convened earlier this year that found 40 to 60% of blood transfusion are given in scenario's in which the transfusion either adds no benefits or adds additional risks beyond infection, while adding no benefit. I have provided a couple links in case anyone would like to look at it. I personally believe it is beneficial to include such information as many are under the presumption that, aside to the rare infection, that the procedure is benign at worst. http://www.englewoodhospital.com/medservices.cfm?pageid=850&bc=0,27,831 http://www.medpagetoday.com/HospitalBasedMedicine/Hospitalists/13869 —Preceding unsigned comment added by 204.9.160.90 (talk) 21:43, 11 December 2009 (UTC)

This is a good point - I've added some content (with references) regarding transfusion inefficacy, specifically regarding RBC storage lesion. Unknown quality/efficacy levels of stored RBC product has been bolstering arguments for using the so-called "restrictive protocol" of avoiding transfusions wherever possible, even if it delays patient recovery. Interprof (talk) 02:43, 25 September 2011 (UTC)

Pope Innocent VIII
What is the point of having the experience of Pope Innocent VIII as the opening statement in the history section? Men had been drinking blood for thousands of years prior to Pope Innocent VIII. Innocent VIII did not experience a blood transfusion. He was fed blood. I propose deleting this material as though it is part of the history of transfusing blood.--Marvin Shilmer (talk) 20:05, 19 January 2010 (UTC)
 * Given the misleading notion that drinking blood is somehow comparable to the subject known today as blood transfusion, and given the fact that reputable historians have debunked the supposed incident of Pope Innocent VIII receiving a transfusion as fable, unless there is an objection otherwise, I’m deleting the information. (See Lindeboom, The Story of a Blood Transfusion to a Pope, Journal of the History of Medicine, October 1954, pp. 455-459; and Gottlieb, History of the First Blood Transfusion but a Fable Agreed Upon: The Transfusion of Blood to a Pope, Transfusion Medicine Reviews, Vol. 5, No. 3, July 1991, pp. 228-235.) -- Marvin Shilmer (talk)

Copyright problem removed
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medico-legal issues related to transfusion
there is no mention of laws related to blood transfusions, blood banks etc. if any one can help? —Preceding unsigned comment added by 117.199.93.231 (talk) 13:37, 13 July 2010 (UTC)

TRALI
From the description itself this seems to be associated with antibodies towards WBC HLA antigen. why is this placed under the heading Non-immunological reactions? AndreiAA —Preceding unsigned comment added by 78.133.29.242 (talk) 08:06, 17 April 2011 (UTC)

moved to the correct section, also citations provided where citation needed tags were there Jimmy joe joeseph (talk) 08:14, 30 May 2011 (UTC)

Volume information
I've removed a section added to the page regarding volume of a "unit" of blood. This is a complicated issue, and it's not very consistent. 450-500 mls are typically collected from a donor in the US, apparently 470 is the UK's standard collection, but this is a unit of whole blood, which is not often used for transfuson. Of that 450-500 mls, the hematocrit of the donor determines what percent is red blood cells. These are typically processed into what are called packed red blood cells, which are 225-350 mls of RBCs with some residual plasma (pure RBCs wouldn't flow). Some of the cites used to support the "450 mls is it" are a bit misleading, one is talking about "how much of a liter of blood is RBCs" rather than a transfusable volume.

This document has a lot of information that might be useful: Circular of Information. It is, however, the US standards. European standards are grossly similar, but not identical. Blood collection and transfusion in China, for example, is quite different, though there are some basic similarities. My understanding is that 200 mls collected was previously typical in China, though that's changing. SDY (talk) 01:20, 24 August 2011 (UTC)

 * Could you write a section on this? If someone says "I had 20 units of blood". I wish to be able to use wikipedia to translate that into volume (m³). Electron9 (talk) 01:25, 24 August 2011 (UTC)

 * I'll second Electron9's request. This is exactly why I came to this page, and then to the talk page to request it.  Including the above in an only slightly edited form would be useful and improve the article.  --Keithonearth (talk) 19:05, 30 April 2012 (UTC)
 * Great, so we now have an article where "unit" of blood is referenced 30 times but nowhere is it shown what a unit of blood actually is. This is the reason wikipedia is going down the toilet. Good work guys. 2A00:23C8:C93:ED01:345B:2CEA:FDB1:1423 (talk) 20:40, 8 July 2022 (UTC)

Primates
Can people get transfustions from non human Primates and is that successful? — Preceding unsigned comment added by Jokem (talk • contribs) 19:29, 9 November 2011 (UTC)

No. Jimmy joe joeseph (talk) 02:45, 28 February 2012 (UTC)

Listen to the experts?
This section of the article reeks of bias. Blood transfusion has saved millions of lives. I suggest that this section either be moved under a new title (perhaps called "criticisms") or be removed entirely. I'm not doing this myself because I'm not sure who put it there in the first place. But seriously, what's next, a section under the polio vaccine page suggesting that it's a plot by communists to take over our children? People need to get real. — Preceding unsigned comment added by 24.253.56.32 (talk) 23:24, 8 April 2012 (UTC)

completeness
The issue about the researcher who used blood from somebody who had malaria and tuberculosis offers an opportunity to discuss the history of blood born diseases affecting blood banks. Need to expand on this. 108.45.122.74 (talk) 12:26, 26 October 2012 (UTC)

Typical wikipedia omits basic facts
So how much is a unit of blood? — Preceding unsigned comment added by 88.106.68.190 (talk) 16:50, 24 August 2013 (UTC)

 * Thankfully a quick look on Google reveals it's ~450 ml. We need a good source to add it to the article though. JFW | T@lk  13:12, 14 October 2013 (UTC)

harles Drew was the first man to use plasma — Preceding unsigned comment added by 66.229.184.247 (talk) 02:34, 10 January 2014 (UTC)

Restrictive transfusion strategies
... are safer in terms of risk of infection and cardiovascular complications 10.1016/j.amjmed.2013.09.017 JFW | T@lk  13:12, 14 October 2013 (UTC)

"Early efforts to transfuse human blood" Needs Cleanup
The first sentence should probably be deleted, or at least moved. The paragraph starts out "The science of blood transfusion dates to the first decade of the 20th century...", and then jumps to a discussion of blood transfusion in the early *nineteenth* century.kmarple1 (talk) 06:59, 9 January 2014 (UTC)

Storage
10.1111/bjh.12747 Br J Haem - prolonged storage of blood may cause harm. JFW | T@lk  19:57, 27 January 2014 (UTC)

 * ... but not necessarily. 10.1182/blood-2015-09-670950 JFW | T@lk  21:01, 28 January 2016 (UTC)

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Compatibility of ABO and Rh system
Receivers with Rhesus minus blood can't receive Rhesus plus blood. The AB- receiver row wrongly describes the possible matches. And the table in the Role of ABO antigens in transfusion medicine section in ABO blood group system page shows that AB+ receivers can receive blood from all blood types, so I made a small adjustment to correct it yesterday. But for whatever reasons, it was reverted. Can anyone explain that? --171.248.123.170 (talk) 04:13, 18 November 2016 (UTC)

wording clarification
First sentence in the subsection 'Infection' is:

"The use of greater amount of red blood cells is associated with a high risk of infections."

Does this mean number of red blood cells? If not, what does it mean, please?

The next sentence also needs clarification:

"In those who were given red blood only with significant anemia infection rates were 12% while in those who were given red blood at milder levels of anemia infection rates were 17%." I take it that this sentence is introducing the concept of patients with significant anemia versus those with milder anemia? If so, how does this relate to the previous sentence's topic, i.e. number/amount of red blood cells?

any help appreciated

-- Ty rS  13:38, 29 March 2017 (UTC)

Can CMV and other viruses be 100% removed or not?
Wikipedia says: "Leukoreduced blood products are LESS likely to cause HLA alloimmunization (development of antibodies against specific blood types), febrile non-hemolytic transfusion reaction, CMV = cytomegalovirus infection, and platelet-transfusion refractoriness".

The source is quite old and I was not able to access it as it requires a subscription. 91.155.24.127 (talk) 14:55, 14 April 2017 (UTC)
 * if you have a new data, please add it.--Bolzanobozen (talk) 15:17, 27 August 2017 (UTC)

NEJM
10.1056/NEJMra1612789 JFW | T@lk  09:10, 28 September 2017 (UTC)

First transfusion
Dr Agote realize the first blood transfusion, he did it before the rector of the university, the dean of the medical school and the mayor of the city of Buenos Aires in November, 1914 and not only published the results, he wrote to all the countries at WWI explaining how to do it. Only when WWI finished, Albert Hustin says that he had done the same thing before, but in science the first is who published first and Hustin only has his word about the date that he supposedly did it, so you are confirming a rumor without evidence. — Preceding unsigned comment added by 186.22.67.17 (talk) 21:05, 13 February 2019 (UTC)

OPS link in infobox is wrong
can it just be deleted if it is wrong and I don't know the correct one?EncycloABC (talk) 17:01, 16 December 2019 (UTC)

Blood unit redirects here
The unit disambiguation page points to blood unit which uselessly redirects here. There needs to be a section explaining this, even if the only thing it says is "it's complicated". For what it's worth, when I had a phlebotomy today, they measured one unit of whole blood as 16 ounces avoirdupois, on a scale. 207.180.169.36 (talk) 04:47, 23 January 2021 (UTC)

Use of enzymes to change blood type to O
In 2007, it was reported in Nature Biotechnology that scientists had found a way to strip blood type enzymes and make blood into type O. They were planning to get regulatory approval for this procedure...whatever became of this? Is it worth mentioning in the article? -- Beland (talk) 20:17, 11 April 2021 (UTC)

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 * Il Manifesto del futurismo di Filippo Tommaso Marinetti (1909)

 * 8. Noi siamo sul promontorio estremo dei secoli!... Perché dovremmo guardarci alle spalle, se vogliamo sfondare le misteriose porte dell’impossibile? Il Tempo e lo Spazio morirono ieri. Noi viviamo già nell’assoluto, poiché abbiamo già creata l’eterna velocità onnipresente.

 * - We stand on the last promontory of the centuries!... Why should we look back, when what we want is to break down the mysterious doors of the Impossible? Time and Space died yesterday. We already live in the absolute, because we have created eternal, omnipresent speed.

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 * This page is a candidate for speedy deletion:

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Diffuse reflection

Diffuse reflection is the reflection of light or other waves or particles from a surface such that a ray incident on the surface is scattered at many angles rather than at just one angle as in the case of specular reflection. An ideal diffuse reflecting surface is said to exhibit Lambertian reflection, meaning that there is equal luminance when viewed from all directions lying in the half-space adjacent to the surface.

A surface built from a non-absorbing powder such as plaster, or from fibers such as paper, or from a polycrystalline material such as white marble, reflects light diffusely with great efficiency. Many common materials exhibit a mixture of specular and diffuse reflection.

The visibility of objects, excluding light-emitting ones, is primarily caused by diffuse reflection of light: it is diffusely-scattered light that forms the image of the object in the observer's eye.

Mechanism

Diffuse reflection from solids is generally not due to surface roughness. A flat surface is indeed required to give specular reflection, but it does not prevent diffuse reflection. A piece of highly polished white marble remains white; no amount of polishing will turn it into a mirror. Polishing produces some specular reflection, but the remaining light continues to be diffusely reflected.

The most general mechanism by which a surface gives diffuse reflection does not involve exactly the surface: most of the light is contributed by scattering centers beneath the surface, as illustrated in Figure 1. If one were to imagine that the figure represents snow, and that the polygons are its (transparent) ice crystallites, an impinging ray is partially reflected (a few percent) by the first particle, enters in it, is again reflected by the interface with the second particle, enters in it, impinges on the third, and so on, generating a series of "primary" scattered rays in random directions, which, in turn, through the same mechanism, generate a large number of "secondary" scattered rays, which generate "tertiary" rays, and so forth. All these rays walk through the snow crystallites, which do not absorb light, until they arrive at the surface and exit in random directions. The result is that the light that was sent out is returned in all directions, so that snow is white despite being made of transparent material (ice crystals).

For simplicity, "reflections" are spoken of here, but more generally the interface between the small particles that constitute many materials is irregular on a scale comparable with light wavelength, so diffuse light is generated at each interface, rather than a single reflected ray, but the story can be told the same way.

This mechanism is very general, because almost all common materials are made of "small things" held together. Mineral materials are generally polycrystalline: one can describe them as made of a 3D mosaic of small, irregularly shaped defective crystals. Organic materials are usually composed of fibers or cells, with their membranes and their complex internal structure. And each interface, inhomogeneity or imperfection can deviate, reflect or scatter light, reproducing the above mechanism.

Few materials do not cause diffuse reflection: among these are metals, which do not allow light to enter; gases, liquids, glass, and transparent plastics (which have a liquid-like amorphous microscopic structure); single crystals, such as some gems or a salt crystal; and some very special materials, such as the tissues which make the cornea and the lens of an eye. These materials can reflect diffusely, however, if their surface is microscopically rough, like in a frost glass (Figure 2), or, of course, if their homogeneous structure deteriorates, as in cataracts of the eye lens.

A surface may also exhibit both specular and diffuse reflection, as is the case, for example, of glossy paints as used in home painting, which give also a fraction of specular reflection, while matte paints give almost exclusively diffuse reflection.

Most materials can give some specular reflection, provided that their surface can be polished to eliminate irregularities comparable with the light wavelength (a fraction of a micrometer). Depending on the material and surface roughness, reflection may be mostly specular, mostly diffuse, or anywhere in between. A few materials, like liquids and glasses, lack the internal subdivisions which produce the subsurface scattering mechanism described above, and so give only specular reflection. Among common materials, only polished metals can reflect light specularly with high efficiency, as in aluminum or silver usually used in mirrors. All other common materials, even when perfectly polished, usually give not more than a few percent specular reflection, except in particular cases, such as grazing angle reflection by a lake, or the total reflection of a glass prism, or when structured in certain complex configurations such as the silvery skin of many fish species or the reflective surface of a dielectric mirror. Diffuse reflection can be highly efficient, as in white materials, due to the summing up of the many subsurface reflections.

Colored objects
Up to this point white objects have been discussed, which do not absorb light. But the above scheme continues to be valid in the case that the material is absorbent. In this case, diffused rays will lose some wavelengths during their walk in the material, and will emerge colored.

Diffusion affects the color of objects in a substantial manner because it determines the average path of light in the material, and hence to which extent the various wavelengths are absorbed. Red ink looks black when it stays in its bottle. Its vivid color is only perceived when it is placed on a scattering material (e.g. paper). This is so because light's path through the paper fibers (and through the ink) is only a fraction of millimeter long. However, light from the bottle has crossed several centimeters of ink and has been heavily absorbed, even in its red wavelengths.

And, when a colored object has both diffuse and specular reflection, usually only the diffuse component is colored. A cherry reflects diffusely red light, absorbs all other colors and has a specular reflection which is essentially white (if the incident light is white light). This is quite general, because, except for metals, the reflectivity of most materials depends on their refractive index, which varies little with the wavelength (though it is this variation that causes the chromatic dispersion in a prism), so that all colors are reflected nearly with the same intensity.

Importance for vision
The vast majority of visible objects are seen primarily by diffuse reflection from their surface. Exceptions include objects with polished (specularly reflecting) surfaces, and objects that themselves emit light. Rayleigh scattering is responsible for the blue color of the sky, and Mie scattering for the white color of the water droplets in clouds.

Interreflection
Diffuse interreflection is a process whereby light reflected from an object strikes other objects in the surrounding area, illuminating them. Diffuse interreflection specifically describes light reflected from objects which are not shiny or specular. In real life terms what this means is that light is reflected off non-shiny surfaces such as the ground, walls, or fabric, to reach areas not directly in view of a light source. If the diffuse surface is colored, the reflected light is also colored, resulting in similar coloration of surrounding objects.

In 3D computer graphics, diffuse interreflection is an important component of global illumination. There are a number of ways to model diffuse interreflection when rendering a scene. Radiosity and photon mapping are two commonly used methods.

Spectroscopy
Diffuse reflectance spectroscopy can be used to determine the absorption spectra of powdered samples in cases where transmission spectroscopy is not feasible. This applies to UV-Vis-NIR spectroscopy or mid-infrared spectroscopy.

title: Diffuse reflection


text:
Talk:Presidential system

South Sudan
What about South Sudan in the map? — Preceding unsigned comment added by Salvadorcases (talk • contribs) 03:41, 17 August 2013 (UTC)

A mishmash
This article is a mess. It mixes up a host of things
 * a presidential system (which BTW doesn't mean a "president". It means "someone who presides", and so applies to monarchs and dictators also)
 * A republican presidential system (which does mean president and is primarily associated with the US and countries who have modelled their constitutional systems on the US).

BTW the claim that presidential system is based on the US system is garbage. It is far older. The US system was for example based on the system of government in Great Britain in the 1770s, with the President stepping into the role of the Crown, and Congress a more clearly defined parliament.

It has also nothing to do with method of selection of a head of state. It has to do with the fact that the executive is not answerable to parliament, so cannot be voted out by a Vote of Confidence. They exist in separate spheres of influence.

I hope no-one used this garbled article in an essay in college. If they did they would have failed. FearÉIREANN \(caint) 20:07, 13 September 2006 (UTC)

 * There are so many parenthetical statements in your comments that I'm not really sure I understand what you're saying. However to say that "presidential system" just means a government with a presiding officer is confuse etymology with definition.

 * I concede that to use "republican presidential system" is a little more precise than just "presidential system," but this article makes it clear that "presidential system" only pertains to republican democracies. The books I have read on this subject, like "Parliamentary Versus Presidential Government" by Arend Lijphart just use "presidential system" without the "republican."

 * This article discusses how the independence of the executive is an important criteria for presidential government too.Dinopup 00:00, 15 September 2006 (UTC)

First sentence: "president is not accountable to the legislature"
Obviously this is false. Each branch of American gov't is accountable to each other branch in at least one way. It's been a while since I had a civics or government class, but two checks/balances of the legislature on the executive immediately come to my mind: (1) impeachemnt and (2) the sole right of congress to declare war (which puts a check on the President in his role as Chief Commander of the A.F.).

The point is, this sounds like a borderline-vandalism comment by someone who doesn't like our current executive--but it is not good information.

 * No, it really doesn't. The article mentions impeachment, which really is the only way the President is directly accountable to Congress. Although Congress posesses powers the President does not and vice versa, Congress cannot hold the President accountable for his actions in any eay except to impeach him. Contrast this to other systems of government, when a legislative body can simply hold a vote to throw out the head of state. --joeOnSunset 00:20, 26 October 2006 (UTC)

 * I agree that the president is accountable to Congress. The argument that the President cannot be removed in the face of impeachment as a fact of the matter is unreasonable. The president is also accountable to the people through elections. In the US, the president is also accountable to his party - which will lose elections in Congress every two years under an unpopular president. —Preceding unsigned comment added by 83.251.254.172 (talk) 10:17, 7 May 2009 (UTC)

"Congressional system" redirects here
I note that Congressional system is a redirect to Presidential system: should it be? There is a (rather unsatisfactory) "article" at Congress: it currently looks like a (very incomplete) disambiguation page. --Mais oui! 08:45, 13 October 2006 (UTC)

Issues with introduction
The introduction to this article seems to have a discernable bias in favor of the British parilamentary form of government and against the American model of separation of powers. It seems historically ill-informed and misleading, possibly deliberately so, and would do well to be rewritten almost entirely to remove the unnecessary comparisons with Britain and focus on introducing the topic in an objective tone. —The preceding unsigned comment was added by 141.161.124.235 (talk) 07:07, 13 December 2006 (UTC).

"military coups to remove a leader who is said to have lost his mandate, as in Salvador Allende"
On the "weaknesses" part there was this phrase: "Since there is no legal way to remove an unpopular president, many presidential countries have experienced military coups to remove a leader who is said to have lost his mandate, as in Salvador Allende." I removed the last four words because I believe them to be biased and propagandistic. Salvador Allende was not removed because "he had lost his mandate". He was killed by foreign-financed blood- thirsty extreme-right coupists, and was replaced by Pinochet, a non-elected, illegitimate military leader who ruled with total disregard for political and human rights. The way this phrase was written made it look like Pinochet did a favour to Chilean people by removing an unpopular president. Quite the opposite is true. —Preceding unsigned comment added by Special:Contributions/ (talk)

Inconsistent use of policy to enforce bias
I noticed that on the assertion that presidential systems tend to have less ideological parties, someone put the tag "citation needed", and yet that tag shows up very rarely in the remainder of the page. I am thus compelled to concluded that this is an abuse of policy for the purposes of enforcing bias.

This is an excellent illustration of why I have historically experienced a very strong negative emotional reaction to Wikipedia's policies more or less in general, if I am honest. Hypocrisy and the enforcement of bias, in the name of supposedly maintaining neutrality, are made far too easy.

Petrus4 (talk) 15:28, 1 January 2008 (UTC)

Presidential Monarchy
Why not have a system with both a president (as head of government and state), a queen just to be traditional, and a legislature (like congress) to make the laws. I think australia should have a system like that. —Preceding unsigned comment added by 203.217.59.87 (talk) 10:13, 20 March 2008 (UTC)

Thats nonsense. Every monarchy should be abolished. Once and for all.84.134.99.161 (talk) 17:12, 15 August 2008 (UTC)

I recognize that I'm replying to a post from a decade ago, but regardless I felt I had to note that there actually have been monarchies that utilized the presidential system in the past (so it's not that bizarre of an idea). The Kingdom of Hawaii's system of government, for example, was patterned closely after that of the US and its States (not surprising, given the influence American missionaries and business interests had in the Kingdom); the monarch was both head of state and government, with powers very similar to those held by the President of the United States, or a Governor of a US State, with regard to executing laws, while an independent legislature made the laws, and an independent judiciary adjudicated the laws, and each branch having a check on the others in the exercise of their functions.—MNTRT2009 (talk) 19:13, 11 July 2018 (UTC)

186.188.238.66 (talk) 02:28, 14 February 2020 (UTC) Hey MNTRT2009, I believe you're talking about a Constitutional Monarchy where the monarch leads the executive, which was the form of government introduced by the first french constitution of the French Revolution. I personally don't like it because I like extremes (Presidential republics/Absolute monarchies), but that's ok. Hey 84.134.99.161, I know you're from Germany and I find it weird that you hate monarchies, since your country didn't suffered evil monarchies...

Where are the...
REFERENCES. I was hoping to get some help finding a site not wikipedia to cite for a paper. Found the info I want, but I need a citation that can withstand criticisms. I dont see a single reference in this article.205.250.62.216 (talk) 01:50, 24 May 2008 (UTC)

Belarus
It's not really a democratie!84.134.57.73 (talk) 13:03, 14 August 2008 (UTC)

More Democratic?
I'm concerned about the passage:

"A prime minister is usually chosen by a few individuals of the legislature, while a president is usually chosen by the people. According to supporters of the presidential system, a popularly elected leadership is inherently more democratic than a leadership chosen by a legislative body, even if the legislative body was itself elected, to rule."

It sounds a little junior-high-school-ish. In the British parliamentary system, the electorate votes for a House of Commons which, in turn, selects a prime minister. In the American presidential system, the electorate votes for an electoral college which, in turn, selects a president. The two seem equivalent. Why does this author think the prime minister is chosen by just "a few individuals of the legislature"? Nothing is offered to support that view.

There are many differences in power, accountability and such between the two officers once they are elected, but that's a separate topic.

--Kjb (talk) 07:22, 6 November 2008 (UTC)G!\m/

 * I would have to disagree with saying that there is no difference between legislators and an electoral college in electing a country's head of state and/or head of government. When the Founding Fathers of the United States established the current system of government at the Constitutional Convention of 1787 (AKA the Philadelphia Convention), they feared having United States Congress elect the president because of the fact that the legislators might put the narrow interests of their constituents above the common good of the nation as a whole and on top of that could be more susceptible to manipulation (via bribery or requests for political favors (or "favours" for those who speak the Queen's English lol). An electoral college that is seperate from the legislature, on the other hand, is far less susceptible to the manipulation of interest groups and politicians being that they are generally sheilded from such groups and individuals (that and the fact that the electors are not chosen until after the commencement of the Presidential election, as opposed to members of Congress of which 90% on average are re-elected to Congress, thus further weakening the grip of politicians and interest groups in deciding who will become President once the Popular vote is complete). They also will be more likely to vote for a president based on what is best for the nation as a whole due to the fact that they do not face the pressure of re-election to serve a constituency that may put more or less importance on certain issues (such as healthcare, abortion, religious issues, and etc.) than what the nation as a whole would. I hope that explains the reasoning of why some countries (the United States in particular in this case) would favor an electoral college to elect a head of state and/or head of government than a legislature. Fuelsaver (talk) 21:56, 30 September 2009 (UTC)

This article should be replaced with several others.
Particularly because it wrongly associates a great deal of nations that all have executive Presidencies and then attempts to describe their systems with a very poor history and interpretation of the American system. Furthermore, the associated image would have you believe that the US and Iran have the same system of government, which is ridiculous--Iran has a Supreme Leader who is above the President, and a very complex system of entrenched councils that make the system very undemocratic. The article should be subdivided into articles about the American Presidential System and countries that use it (the US, et al) or some derived variation (Brazil, et al), as well as dictatorships with nominal legislatures whose dictators call themselves "President" (Cuba, et al). —Preceding unsigned comment added by 68.33.32.75 (talk) 19:12, 2 May 2009 (UTC)

 * The article contains almost no references and represents individual opinion. It presents a POV starting with the very term being used - a propaganda term. In describing the US - its basis is ignorance of the underlying political ideals - especially "a nation of laws and not of people." I note people arguing in support of this article comparing the "Presidential system" in the US to older European monarchies, etc. - in exact opposition to the nature sought by the designers of the US system. A clear distinction between the two is that in the US, the president is bound by the laws and the laws are directly checked for abuse of power (at least in the absense of corruption). Also notably, the US Constitution defines the Legislative Branch first, not the Executive; as they regarded the Legislative as being the most important. They also defined this federal part of overall government as having a very limited role in the affairs of the country. Thus, at least in intent and by definition - this article presents an invalid POV, no references are given to support the POV (only a couple of quotes in support of the POV, perhaps taken out of context), and no light is shown on the fact that the term "Presidential system" is used by a limited number of people and is generally contraversial. I believe that the article should be removed. —Preceding unsigned comment added by 83.251.254.172 (talk) 10:28, 7 May 2009 (UTC)

A topic of .....
Presidential rotation system has been added based on the following http://scholar.google.com/scholar?hl=en&q=%22presidential+rotation+system%22&btnG=Search --222.64.211.94 (talk) 10:04, 21 July 2009 (UTC)

so that all the dirty tricks maintain within a party, instead of spreading to the public

--222.64.211.94 (talk) 10:08, 21 July 2009 (UTC)

Move
Presidential system → Civil government presidential political system — This system is only used in civil government, not in politics (eg religiuos politics, ...) as a whole User:91.176.13.181 13:37, 2 August 2009 (UTC)
 * Please discuss this multiple page move request here. Jafeluv (talk) 02:35, 3 August 2009 (UTC)

Move discussion in process
There is a move discussion in progress on Talk:Politician which affects this page. Please participate on that page and not in this talk page section. Thank you. RFC bot (talk) 01:00, 8 August 2009 (UTC)

POV?
While I agree that the article needs more references, it seems to be a rather balanced article, so I don't understand Tocino's POV tag. Tocino, can you give some examples of non-neutral statements or undue weight on particular points of view? rspεεr (talk) 17:23, 3 December 2009 (UTC)

Bias against the United States
This article is an absolute disgrace. The United States founded the presidential system as we know it, but the credit is given to European monarchies which has little to nothing in similarity. This article has been completely manipulated by typical arrogant europhiles. And on top of it, the US is accused as having an "Imperial Presidential system" What a load of S#2%T! Lets not rape history with our anti-americanism people. Give credit where credit is due. — Preceding unsigned comment added by 68.192.108.42 (talk)

 * I've removed some of the offedning text from the LEad. SInce it's about the presidential system, there;'s no need to take up half the space talking aboaut manarchies. Thant can go in a historical background section, with proper sources. - BilCat (talk) 04:14, 6 February 2010 (UTC)

 * I have no issues with the change, but I think it's important to point out, that for all intents and purposes, what the Americans have is (To quote David Starkey) "An Elective Monarchy with a strong upper chamber". The Founding Fathers took what they felt was good about Constitutional Monarchies and attempted to put in "safe guards".  As for your comment that the US has an Imperial Presidential System, at certain times in American history, this comment hits the nail on the head.  When the President and Congress are of the same party, an Imperial President is essentially what happens.  I don't say this as a bad thing, only because its an issue common to MANY, if not MOST forms of Government when Majorities are formed. Dphilp75 (talk) 15:26, 13 February 2010 (UTC)

 * Yet the US system is the only one for which "Imperial" appears to be used. Hence the bias. Also, though the US has a party system, party disciple is not near-automatic as in many parlimentry system, so one party-rule is not as "imperial" as in other systems. Hence the bias. - BilCat (talk) 15:47, 13 February 2010 (UTC)

 * I agree that largely the term "Imperial" in regards to a President is mostly used "against" the United States, but let's face it, that's what you get for being the biggest, most popular kid on the block. I'm not sure that I agree this amounts to a bias.

 * Further, I also agree that Party Discipline in the U.S. is nothing like it is in the UK, much less Canada, but again, historically speaking a President who enjoys his party having control over Congress does result in exactly what we are talking about. More often than not, such situations result in grumbling through out the party, but very few votes against the President's agenda.

 * Again, this is a problem inherent to MOST forms of "Democracy" in which Majorities can be formed. I'm certainly not bashing the U.S. on this issue; I simply want to make sure that the "truth" of the matter is acknowledged. Dphilp75 (talk) 16:02, 13 February 2010 (UTC)

 * I have no problem with the "truth" being acknowledged, as long as it is cited from verifiable reliable sources, and the US is not singled out as if it were an abberation. There is a difference between a strong prsidential system and an "imperial" one, regardless of the tendecy of politicl scientists to hyperbolize. Hugo Chavez is an example of the latter, not any US president, as they all have left office one way or another.

 * I mean ZERO offense when I say this, but I think you may have a misunderstanding of the term. An Imperial President does not mean that they stay in office. It refers to a President who is able to act with "Imperial" powers, in so much as whatever actions he sees fit to take, is taken.  This happens when the U.S. President has control of Congress.  Let's be honest about this; A Democrat President with a Democrat Congress is, largely, the definition of an "Imperial President".
 * While I sympathize with your desire not to single out the U.S., it is the most obvious and preeminent example of the term, under the above circumstances. If it is just more examples you are looking for, I would point out that the President of France is in a VERY similar situation as the President of the United States, as are numerous other republics.
 * Going back to what I said about the problem being an issue with almost any Political system where majorities can be formed, we can point out the President of Germany is largely nothing more than an elected "Monarchical Figurehead", one could never accuse Germany of having an Imperial President, yet could easily suggest that under like circumstances, they would have an Imperial Chancellor.
 * I am assuming that you are an American yourself, (?) and I would urge you to take a step back from a Nationalist viewpoint and look at it with the facts. Dphilp75 (talk) 18:43, 13 February 2010 (UTC)

 * Wanting something to be reported neutrally and in the correct context is nationalistic?? Please! - BilCat (talk) 19:04, 13 February 2010 (UTC)

 * Sounds like we'd best wait for others to weigh in, as it appears that neither of us is getting the others point. 19:10, 13 February 2010 (UTC) —Preceding unsigned comment added by Dphilp75 (talk • contribs)

 * If this is your point, the yes, we need more opinions, preferably some genuinel neutral ones. I'm done arguing with you. - BilCat (talk) 19:16, 13 February 2010 (UTC)
 * I'm not arguing with you now. I suggested that we wait for others to weigh in. I apologize if I have come across a little strong on this issue, and I assure you that it was never my intention to offend you!  Let's allow time for others to drop their voices in and we'll go from there.Dphilp75 (talk) 19:23, 13 February 2010 (UTC)

 * Imperial President is an interesting term. I've never heard it used before but growing up north of the border (Canada) the way I was taught about the US system was that it was essentially an elected monarchy. The powers of the president equalled that of a monarch from the 18th century. Which seems fairly accurate when you consider how "important" Americans consider their president, how much protection they're afforded, how proper they're expected to act, and how much actual power they wield in the government. Imperial President makes sense to me as a term. I don't really think it singles the United States out. The US is a large country and one of the earliest presidential systems in modern times. It makes sense that many people would give examples that use the United States. I wouldn't call this "bias" per se. Honestly, it seems more like US-centrism.

 * Also, with regards to party discipline, I believe Canada has one of the strongest systems of "party discipline" in the west. That has the unfortunate effect of allowing the Prime Minister to implement any ideological policy he wishes, with no opposition, in the case of majority governments (especially if he can appoint many people to the senate and get a majority there, too). However, I would disagree that this would make him an "Imperial Prime Minster" (as stated earlier) because the Prime Minister cannot sign bills in to law. They still require royal assent and the Governor General (or the Queen) can withhold their consent, even if it is highly unlikely and unusual. It was thought that Governor General Johnston might withhold his signature on a contraversial bill that sought to dismantle the Wheat Board. Liberal Party (interim) leader Bob Rae even wrote him a letter urging him to do so. Celynn (talk) 06:49, 18 December 2011 (UTC)

No History
No credit to the inventor. No progression. No... —Preceding unsigned comment added by 74.250.14.249 (talk) 20:24, 9 June 2010 (UTC)

"Paraguay"
The Republic of Paraguay adopts as its system of government a representative, participatory, and pluralistic democracy, which is founded on the recognition of human dignity. Paraguay is a Republic with an executive president dependent on a parliament.

Article 225 About Procedures (1) The president of the Republic, the vice president, cabinet ministers, justices of the Supreme Court, the attorney general, the public defender, the comptroller-general and the deputy comptroller-general of the Republic, and members of the Superior Electoral Court may be forced to undergo impeachment proceedings for malfeasance in office, for crimes committed in office, or for common crimes. (2) The Chamber of Deputies, by a two-thirds majority, will press the respective charges. The Senate, by a two-thirds absolute majority, will conduct a public trial of those charged by the Chamber of Deputies and, if appropriate, will declare them guilty for the sole purpose of removing them from office. In cases in which it appears that common crimes have been committed, the files on the respective impeachment proceedings will be referred to a competent court.

Besides, the Duties and Powers of Congress are, to approve the national budget once a year, and approve or reject treaties or other international agreements signed by the president of the Republic, to approve or to reject loan agreements, authorize, for a limited period of time, concessions for the exploitation of national or multinational public services or of assets belonging to the State, as well as for the extraction and processing of solid, liquid, or gaseous minerals, to "receive annually from the president of the Republic, at the start of each regular period of sessions, a report on the general situation of the country, on its administration, and government plans", to approve or reject, either partially or totally, after hearing the respective report by the Comptroller-General of the Republic, the report on the details and justification of public financial income and expenses related to the implementation of the budget, and many others. http://www.servat.unibe.ch/icl/pa00000_.html

Excuse my English (186.188.238.66 (talk) 02:34, 14 February 2020 (UTC) your english is indeed horrible, you should avoid using Google Translator here), Regards, Carlos Flores.

 * From what you have posted, that does not sound like the President is dependent on Congress. He is not elected by Congress, and Congress cannot remove him except by a special impeachment process with special supermajorities. The fact that he is required to make a 'state of the nation'-type report does not make him "dependent". The characteristic that defines "President dependent on Parliament" republics is that the President is removed if he loses a confidence vote in Parliament, and therefore that the President can only stay in office as long as his party or coalition has a majority in Parliament. This does not seem to be the case in Paraguay; the system there seems to be very similar to that in the USA, which is the standard example of a presidential system. - htonl (talk) 07:13, 23 November 2012 (UTC)

 * "The characteristic that defines "President dependent on Parliament" republics is that the President is removed if he loses a confidence vote in Parliament, and therefore that the President can only stay in office as long as his party or coalition has a majority in Parliament". And it's how work in Paraguay, Fernando Lugo, elected President of Paraguay in 2008, was impeached and removed from office by the Congress of Paraguay in June 2012. On 21 June the Chamber of Deputies voted 76 to 1 to impeach Lugo, and the Senate removed him from office the following day, by 39 votes to 4, resulting in Vice President Federico Franco, becoming President.
 * Background- Lugo was aided by the presence of Federico Franco of the traditional opposition party Authentic Radical Liberal Party (PLRA) on the ticket as Vice Presidential candidate. Lugo's electoral coalition, Patriotic Alliance for Change (APC), was able to elect him as President (gaining 42.3% of the vote, against the second-placed Colorado candidate's 31.8%). However the Liberals and Colorados retained a majority of both houses of Congress. The Liberal Party, initially a member of the Alliance, withdrew in 2009, leaving the Alliance with just a handful of Congressional seats. http://en.wikipedia.org/wiki/Impeachment_of_Fernando_Lugo

 * Excuse my English. Regards. Carlos Flores.-

 * Impeachment is not the same thing as a loss of confidence vote. If I understand what you posted about Article 225 above, it required a two-thirds absolute majority in each of the Houses of Congress to impeach the President. A confidence vote is just an ordinary majority vote, in most cases only in the lower house. The other big difference is that impeachment is only "for malfeasance in office, for crimes committed in office, or for common crimes". A President who is dependent on Parliament is required to resign just because he loses his parliamentary support, not because he is accused of anything criminal. - htonl (talk) 09:21, 23 November 2012 (UTC)
 * Indeed the confidence vote is not made by a simple majority in Paraguay, but the word "Impeachment" and the translation is what can confuse, but impeachment in Paraguay, it's not necessarily for a criminal thing, only in cases in which it appears that common crimes have been committed, the files on the respective impeachment proceedings will be referred to a "competent court".
 * The Paraguayan Constitution in effect is based on the U.S. Constitution, but due to prolonged presidential dictatorship, the Constitution was drafted in 1992 gives greater powers to parliament, which is the only body that judges the other state bodies, in fact nowhere mentioned the "presidential system" is the system of government in the constitution.
 * Precisely this is why the system in Paraguay, is somewhat different from other presidential systems of the countries of South America.
 * This is an interview where one of the constituents that drafted, explains because it gives greater powers to parliament. (sorry is in Spanish). http://www.ultimahora.com/notas/538091-Esta-Constitucion-garantizo-el-proceso-electoral-democratico
 * Excuse my English. Regards. Carlos Flores.- — Preceding unsigned comment added by 181.125.33.22 (talk) 10:58, 23 November 2012 (UTC)
 * I must remind you, that the 1992 constitution of Paraguay is very different from the 1967 constitution, that if it was a "presidential system", for example the President can not dissolve the legislative power and through the Executive Decree Disappears Law, added more powers of parliament:
 * -The Presidents of the two Houses of Congress come in the order of presidential succession, after the Vice President (Art. 234), as it did in 1999: "As the president of Paraguay's legislature, Luis Ángel González Macchi succeeded to the office of president on March 29, 1999 Following Six Days Earlier the assassination of the Vice President Luis Maria Argana, and the subsequent resignation of President Raul Cubas among accusations That the assassination was linked to Cubas's political movement.
 * -He embodies the confidence vote, with recommendation of removal from office (Art. 194).
 * -The vetoed of the president can be rejected by an absolute majority (Arts. 208 and 209), and not by a two-thirds majority (Art. 158/67).
 * . http://www.servat.unibe.ch/icl/pa00000_.html
 * Changes in the presidential system in the context of constitutional reform, entailed a need to seek consensus and agreements between the Executive and the Legislative to govern. Governance is closely linked to the potential presidential parliamentary alliances in Congress to achieve results in managing and overcoming conflicts of interest within the hegemonic party.
 * In other words, Paraguay with the constitution of 1992, is a joint government between parliament and the executive, there is no separation of powers which proclaim the "presidential system". Paraguay does not have a presidential system.
 * Excuse my English. Regards. Carlos Flores.- — Preceding unsigned comment added by 181.125.155.59 (talk) 22:11, 23 November 2012 (UTC)

 * I can't actually see a significant difference between the Paraguayan system and the system in the United States, which is the standard example of a presidential system. The main characteristic of the presidential system is not about how much power the president has and how much the parliament has. It is about how the president is elected and removed. The article about Lugo's impeachment itself makes clear that the impeachment was considered very unusual, and even referred to as a "coup". In a system with a president who depends on parliament, it is a normal part of politics if parliament removes a president by a confidence vote. - htonl (talk) 22:28, 23 November 2012 (UTC)
 * Yes, it was declared as a coup for countries with a strong presidential system, such as Venezuela, Bolivia and Argentina, (and by followers of Lugo) but for example, i know the constitution of Argentina and is different because the judge is in charge of the supreme court, and is accusing by the congress, it's hard for them, to understand what is, "loses a confidence vote". Moreover even some Argentine journalists rated the Paraguayan system as parliamentarism. "what in the Paraguayan Constitution is a political judgment, in Unasur is called breakdown of democracy and parliamentarism in Europe would be called: a censure motion leading to a change of government."http://elestadista.com.ar/?p=2442
 * But that's not an encyclopedic discussion was to judge whether or not coup, the technical body charged with judging the constitutionality and if you follow the constitution in Paraguay is the Supreme Court of Paraguay, and the electoral court, declared that Lugo had been duly removed from office under Article 225, and that Correctly Federico Franco had succeeded as President under Article 234. see "the Impeachment of Fernando Lugo", but the only thing clear, from the court decision, the case of Gonzales Macchi in 1999 or this, about Lugo in this year, is that, in Paraguay don't exist a real separation of power between the executive and the legislature, so we can't be said that is a "full presidential system". Excuse my English. Regards. Carlos Flores.- — Preceding unsigned comment added by 181.125.155.59 (talk) 00:21, 24 November 2012 (UTC)

Gridlock is a bad thing?
This article cites gridlock as a criticism of the presidential system. It doesn't seem to state that for many Gridlock is a very desirable result. This is because anything that can be done quickly will likely be done poorly and having congress and the president too friendly will result in things being passed to quickly to be properly debated and not give constituents time to mount an opposition. A prime example of this would be the recent passage of Obamacare which only passed because of the lack of gridlock and polls have shown a strong preference for repeal ever since.Drewder (talk) 14:02, 13 January 2013 (UTC)

Thailand's inclusion within Color legend displayed on World map
There's a certain shade of Green that represents Thailand. Why is it being excluded as a legend color with this specific Green? It's description for this color's representation should be like all of the others. If you take a good look at the map, there's one more color missing within it's equation since their's no description to describe Thailand that's shaded in a specific type of Green. There's basically no color legend for Thailand's representation within this subject matter. — Preceding unsigned comment added by Cod1337 (talk • contribs) 22:10, 2 July 2015 (UTC)

Mistake in the definition
Opening sentence reads "presidential system is a system of government where a head of government is also head of state and leads an executive branch", but the "Presidential systems with a prime minister" section contains examples to the contrary. (e.g. Azerbaijan's head of government (prime minister) is not the head of state.) Either those countries should be removed or the definition should be corrected.--209.6.192.134 (talk) 02:46, 29 September 2015 (UTC)
 * There is also the case of Namibia in, which, despite the President is both the head of state and government, according to Article 41 of the Constitution of the Republic of Namibia, all the government members are individually and collectively responsible to the legislature, thus making Namibia not to have a full and strict separation of powers and as well the ministry are being subject to parliamentary confidence. And I guess Mozambique has a similar case to this one. --B.Lameira (talk) 15:49, 15 December 2015 (UTC)
 * Peru has the same case that of Namibia, President is both head of state and government, but the government members are responsible to the legislature according to the articles in Chapter VI of the Peruvian Constitution. --B.Lameira (talk) 19:02, 16 December 2015 (UTC)

"Citation needed"
"Cabinet ministers or executive departmental chiefs are not members of the legislature."

 * I don't know about presidential systems in general, but this is true of the US system in particular. Article 1, Section 6, Clause 2 of the US Constitution states that "no Person holding any Office under the United States, shall be a Member of either House during his Continuance in Office." --Khajidha (talk) 12:45, 2 May 2017 (UTC)

Suriname, Micronesia, Marshall Islands, Nauru, Botswana and Kiribati
Can i add Suriname, Micronesia, Marshall Islands, Nauru, Botswana and Kiribati can i add this country to Presidential system because they have Presidents and Vice Presidents and the President is the head of both state and government.

 * Are you sure about this? The politics pages on Suriname, Nauru, Botswana and Kiribati do say that the President is head of state and government rolled into one, but they still describe these countries as parliamentary. The Marshall Islands page says the country is mixed parliamentary-presidential. Might be an edge case, idk. I can't tell what the deal with the Federated States of Micronesia is. Might be an edge case too. Damvile (talk) 11:30, 1 October 2018 (UTC)

These countries use a form of parliamentary system where the president is simultaneously a prime minister in all but name, and requires the confidence of parliament to stay in office.--Idlem (talk) 07:07, 15 May 2020 (UTC)

Azerbaijan's map
Pls redact our map! Because Garabagh is not a part of any country. This is our region! Ordu Khan (talk) 09:10, 29 November 2019 (UTC)

Please remove the comparison between a Presidential Republic and a Parliamentary one
186.188.238.66 (talk) 02:38, 14 February 2020 (UTC) This article is about the Presidential system of government (which is a type of republican government), but this page is not suited to make a comparison between such a system and a parliamentary one. I feel this article is discriminating against Presidential Republics, which is an insult to such a system. We need to find a solution to this, but I suggest removing any mention of the Parliamentary system, for now at least. This article is very bad and unprofessional... Presidential republics are not "the Congressional system"...

The list of presidential systems with a prime minister includes semi-presidential countries
Maurice Duverger defined semi-presidentialism as a system where: 1) The president is popularly elected; 2) The president has considerable power; 3) The president shares executives power with a prime minister responsible to the parliament.

Belarus and Kazakhstan use a semi-presidential system. The popularly-elected president is chairperson of the executive branch and possesses considerable discretionary power. The Cabinet's term in office depends on the parliament, meeting the third conditions. Furthermore, bills can be drafted by the president's Cabinet or the president directly, a common feature of semi-presidential countries (such as France), but antithetical of the "checks and balances" of a presidential system.

Would anyone object that I move Belarus and Kazakhstan to the page semi-presidential system? If any other countries belong there as well, let me know (I suspect it's the entire list of these countries with prime ministers, but this might be too radical).--Idlem (talk) 05:47, 14 May 2020 (UTC)

 * Sure, just remember to also amend their corresponding articles, List of countries by system of government and preferably also the File:Forms of government.svg (beware you'll likely have to do it through the talk page, as it's edit-protected). Fuse809  (contribs · email · talk · uploads) 06:58, 4 August 2020 (UTC)

Peru?
Peru is really a presidential system? The parliament could sack the government, and some source call it semi-presidential (example).--MiguelMadeira (talk) 13:16, 2 August 2021 (UTC)

India
India do not have a Presidential system.So it is wise to remove it.

A Commons file used on this page or its Wikidata item has been nominated for deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 17:37, 19 August 2021 (UTC)
 * Flag of the Islamic Emirate of Afghanistan.svg

Restructure
I've made several changes to restructure the article. In its previous state, the information was mostly sorted into a pros and cons style, lacked any sort of sourcing, and was generally disorganized. I've moved most of the content into the "Characteristics" section and sorted it by different aspects of the system to better comply with style guidelines. I've done what I can to source the information, and I've rewritten portions of the article to be more concise or better comply with sources. The only section I removed outright was "Impediments to leadership change," which was a large section that consisted of a back-and-forth tangent with original research. I've also added a history section and generously applied citation needed tags where necessary. Thebiguglyalien (talk) 07:14, 2 March 2022 (UTC)

The Philippine Constitution of 1899
"Following the pattern of other Spanish colonies, the Philippines established the first presidential system in Asia in 1898" is NOT accurate. The 1899 Malolos Constitution was Parliamentary in form rather than a "single executive system" as defined by the Wikipedia entry.

See Malolos Constitution and https://www.officialgazette.gov.ph/constitutions/the-1899-malolos-constitution/ Obed.ello (talk) 03:37, 29 July 2022 (UTC)

Sri Lanka is a semi-presidential republic
The Democratic Socialist Republic of Sri Lanka is a unitary semi-presidential republic, according to the Constitution. The executive power is vested in the government. The President is the head of state and is also head of government and head of the executive. But the President is not the sole executive and shares power with the Prime Minister. The President appoints the Prime Minister, who is a Member of Parliament that commands the confidence of the house. Ministers are appointed by the President on the advice of the Prime Minister. Hence the Prime Minister and the Ministers derive their powers from the Parliament, and are dually accountable to both the President and the Parliament, much like in the parliamentary system. Parliament has the power to remove the Prime Minister by a motion of no confidence. Hence, Sri Lanka is a semi-presidential republic In the Presidential system the government is independent of the legislature, but the power of the Government of Sri Lanka depends on Parliament, unlike in the presidential system.

https://www.parliament.lk/files/pdf/constitution.pdf The Sri Lanka (talk) 16:29, 14 November 2022 (UTC)

 * @The Sri Lanka: The constitution of Sri Lanka is a primary source. Using a primary source for this information is considered original research, and is not permitted by Wikipedia policy. If you have a reliable secondary source to support this, then the changes can be reconsidered. For now, No original research requires your change to be reverted, but once you have a secondary source, then the article can be corrected. For now, it complies with Verifiability, even if it isn't true. I know this seems frustrating, but we are all here to build an encyclopaedia, and this isn't an adversarial system. I will add a template to the entry though, to make it clear that this may not be correct, even though it is "verifiable". Mako001 (C)  (T)  🇺🇦 23:25, 14 November 2022 (UTC)
 * I would like to thank you for raising this though, there are some major issues with sourcing on the topic of what system of government various countries use. I am actually inclined to belive that your version is correct here, but verifiability is one of the Five pillars of Wikipedia. Mako001 (C) (T)  🇺🇦 23:39, 14 November 2022 (UTC)

Countries with limited recognition
There should be consensus regarding the inclusion of countries with limited recognition. It would be better to include only countries which are recognised by at least one UN member state. Please share your thoughts and ideas in this regard. The Sri Lanka (talk) 14:44, 20 November 2022 (UTC)

Split Section Presidentialism metrics into Article Presidentialism metrics
HudecEmil (talk) 09:24, 11 June 2023 (UTC)

UK Monarch has significant power
In the UK, the monarch can dissolve or prorogue parliament, dismiss and appoint the prime minister and to veto any act passed by parliament. These powers have not been used recently, but the caption states that "this chart represent de jure systems of government, not the de facto degree of democracy" and these de jure powers border on absolute monarchy, so perhaps the UK should be coloured in as a semi-constitutional monarchy? Edward Jocob Philip Smith (talk) 19:16, 9 May 2024 (UTC)
 * While there is obviously overlap, the UK is much closer to a parliamentary democracy that a constitutional monarchy - the king’s powers are mostly notional. KJP1 (talk) 14:13, 10 May 2024 (UTC)

title: Talk:Presidential system


text:
Specular reflection

Specular reflection, or regular reflection, is the mirror-like reflection of waves, such as light, from a surface.

The law of reflection states that a reflected ray of light emerges from the reflecting surface at the same angle to the surface normal as the incident ray, but on the opposing side of the surface normal in the plane formed by the incident and reflected rays. This behavior was first described by Hero of Alexandria (AD c. 10–70). Later, Alhazen gave a complete statement of the law of reflection. He was first to state that the incident ray, the reflected ray, and the normal to the surface all lie in a same plane perpendicular to reflecting plane.

Specular reflection may be contrasted with diffuse reflection, in which light is scattered away from the surface in a range of directions.

Law of reflection
When light encounters a boundary of a material, it is affected by the optical and electronic response functions of the material to electromagnetic waves. Optical processes, which comprise reflection and refraction, are expressed by the difference of the refractive index on both sides of the boundary, whereas reflectance and absorption are the real and imaginary parts of the response due to the electronic structure of the material. The degree of participation of each of these processes in the transmission is a function of the frequency, or wavelength, of the light, its polarization, and its angle of incidence. In general, reflection increases with increasing angle of incidence, and with increasing absorptivity at the boundary. The Fresnel equations describe the physics at the optical boundary.

Reflection may occur as specular, or mirror-like, reflection and diffuse reflection. Specular reflection reflects all light which arrives from a given direction at the same angle, whereas diffuse reflection reflects light in a broad range of directions. The distinction may be illustrated with surfaces coated with glossy paint and matte paint. Matte paints exhibit essentially complete diffuse reflection, while glossy paints show a larger component of specular behavior. A surface built from a non-absorbing powder, such as plaster, can be a nearly perfect diffuser, whereas polished metallic objects can specularly reflect light very efficiently. The reflecting material of mirrors is usually aluminum or silver.

Light propagates in space as a wave front of electromagnetic fields. A ray of light is characterized by the direction normal to the wave front (wave normal). When a ray encounters a surface, the angle that the wave normal makes with respect to the surface normal is called the angle of incidence and the plane defined by both directions is the plane of incidence. Reflection of the incident ray also occurs in the plane of incidence.

The law of reflection states that the angle of reflection of a ray equals the angle of incidence, and that the incident direction, the surface normal, and the reflected direction are coplanar.

When the light impinges perpendicularly to the surface, it is reflected straight back in the source direction.

The phenomenon of reflection arises from the diffraction of a plane wave on a flat boundary. When the boundary size is much larger than the wavelength, then the electromagnetic fields at the boundary are oscillating exactly in phase only for the specular direction.

Vector formulation
The law of reflection can also be equivalently expressed using linear algebra. The direction of a reflected ray is determined by the vector of incidence and the surface normal vector. Given an incident direction $$\mathbf{\hat{d}}_\mathrm{i}$$ from the light source to the surface and the surface normal direction $$\mathbf{\hat{d}}_\mathrm{n},$$ the specularly reflected direction $$\mathbf{\hat{d}}_\mathrm{s}$$ (all unit vectors) is:

 * $$\mathbf{\hat{d}}_\mathrm{s} = \mathbf{\hat{d}}_\mathrm{i} - 2 \mathbf{\hat{d}}_\mathrm{n} \left(\mathbf{\hat{d}}_\mathrm{n} \cdot \mathbf{\hat{d}}_\mathrm{i}\right),

$$

where $$\mathbf{\hat{d}}_\mathrm{n} \cdot \mathbf{\hat{d}}_\mathrm{i}$$ is a scalar obtained with the dot product. Different authors may define the incident and reflection directions with different signs. Assuming these Euclidean vectors are represented in column form, the equation can be equivalently expressed as a matrix-vector multiplication:

 * $$\mathbf{\hat{d}}_\mathrm{s} = \mathbf{R} \; \mathbf{\hat{d}}_\mathrm{i},$$

where $$\mathbf{R}$$ is the so-called Householder transformation matrix, defined as:

 * $$\mathbf{R} = \mathbf{I} - 2 \mathbf{\hat{d}}_\mathrm{n} \mathbf{\hat{d}}_\mathrm{n}^\mathrm{T};$$

in terms of the identity matrix $$\mathbf{I}$$ and twice the outer product of $$\mathbf{\hat{d}}_\mathrm{n}$$.

Reflectivity
Reflectivity is the ratio of the power of the reflected wave to that of the incident wave. It is a function of the wavelength of radiation, and is related to the refractive index of the material as expressed by Fresnel's equations. In regions of the electromagnetic spectrum in which absorption by the material is significant, it is related to the electronic absorption spectrum through the imaginary component of the complex refractive index. The electronic absorption spectrum of an opaque material, which is difficult or impossible to measure directly, may therefore be indirectly determined from the reflection spectrum by a Kramers-Kronig transform. The polarization of the reflected light depends on the symmetry of the arrangement of the incident probing light with respect to the absorbing transitions dipole moments in the material.

Measurement of specular reflection is performed with normal or varying incidence reflection spectrophotometers (reflectometer) using a scanning variable-wavelength light source. Lower quality measurements using a glossmeter quantify the glossy appearance of a surface in gloss units.

Internal reflection
When light is propagating in a material and strikes an interface with a material of lower index of refraction, some of the light is reflected. If the angle of incidence is greater than the critical angle, total internal reflection occurs: all of the light is reflected. The critical angle can be shown to be given by
 * $$\theta_\text{crit} = \arcsin\!\left(\frac{n_2}{n_1}\right)\!.$$

Polarization
When light strikes an interface between two materials, the reflected light is generally partially polarized. However, if the light strikes the interface at Brewster's angle, the reflected light is completely linearly polarized parallel to the interface. Brewster's angle is given by
 * $$\theta_\mathrm{B} = \arctan\!\left(\frac{n_2}{n_1}\right)\!.$$

Reflected images
The image in a flat mirror has these features:
 * It is the same distance behind the mirror as the object is in front.
 * It is the same size as the object.
 * It is the right way up (erect).
 * It is reversed.
 * It is virtual, meaning that the image appears to be behind the mirror, and cannot be projected onto a screen.

The reversal of images by a plane mirror is perceived differently depending on the circumstances. In many cases, the image in a mirror appears to be reversed from left to right. If a flat mirror is mounted on the ceiling it can appear to reverse up and down if a person stands under it and looks up at it. Similarly a car turning left will still appear to be turning left in the rear view mirror for the driver of a car in front of it. The reversal of directions, or lack thereof, depends on how the directions are defined. More specifically a mirror changes the handedness of the coordinate system, one axis of the coordinate system appears to be reversed, and the chirality of the image may change. For example, the image of a right shoe will look like a left shoe.

Examples
A classic example of specular reflection is a mirror, which is specifically designed for specular reflection.

In addition to visible light, specular reflection can be observed in the ionospheric reflection of radiowaves and the reflection of radio- or microwave radar signals by flying objects. The measurement technique of x-ray reflectivity exploits specular reflectivity to study thin films and interfaces with sub-nanometer resolution, using either modern laboratory sources or synchrotron x-rays.

Non-electromagnetic waves can also exhibit specular reflection, as in acoustic mirrors which reflect sound, and atomic mirrors, which reflect neutral atoms. For the efficient reflection of atoms from a solid-state mirror, very cold atoms and/or grazing incidence are used in order to provide significant quantum reflection; ridged mirrors are used to enhance the specular reflection of atoms. Neutron reflectometry uses specular reflection to study material surfaces and thin film interfaces in an analogous fashion to x-ray reflectivity.

title: Specular reflection


text:
Cat's paw (knot)

The Cat's paw is a knot used for connecting a rope to an object. It is very similar to the cow hitch except there is an additional twist on each side of the bight, making it less prone to slipping.

"The cat's-paw is the common hook hitch for slings. It is the same basic form as the bale sling hitch but has additional twists. Brady says "two or three altogether," and Steel, who mentioned the name in 1794, says "three twists." It is the best of all sling hitches and is often recommended for a slippery rope. But no hitch can slip when tied in a slings since it has no ends. All that is needed is a hitch that cannot jam, and this requirement the cat's-paw fills admirably. The knot spills instantly when removed from the hook. It is the hitch always used for heavy lifts."

- The Ashley Book of Knots

Uses

 * Attaching a sling (a rope that has been formed into a continuous loop) to a hook

Comments
The knot balances the load between the two halves of the hitch, and is used in wharfs and docks. If one half fails, the other should hold until the load can be safely and swiftly lowered to the ground.

When the sling is long the knot can be pre-formed in anywhere in it, then slid over the end of a hook or post.

Structure
Formed from a bight turned up over itself (like a girth hitch) but with extra twists on each side to achieve the desired friction.

Method 1
Form a bight in the middle of the line, and pull it back over itself like a girth hitch. This forms two loops, turned in opposite directions. Convert each loop into an elbow by adding a twist in the direction that will tend to tighten them (the wrong direction will undo the loop completely). Pass both elbow over the hook, rail or post and pull tight, taking care to push the bight up snugly against the turns.

Method 2
If working end of the line has an eye in it, and the standing end is accessible, the knot can be tied to a closed ring, another eye, or a rail with inaccessible ends, as follows. Pass the eye around the ring or rail, then pass the standing end through its own eye (this effectively forms a girth hitch). Then pass the standing end through the eye again, and pull up tight, taking care to push the bight up snugly against the turns.

When using the cat's paw to join two eyes, this process may be repeated several times to give several turns - as many as five in a fine fishing monofilament. Then when tightened, instead of pulling the bight up against the turns, both eyes are pulled equally, to make neat coils of turns in both eyes, meeting halfway between them.

title: Cat's paw (knot)


text:
Cat's paw

Cat's paw or Catspaw may refer to:

 * "Cat's paw", an idiom, meaning "the dupe (or unwitting tool) of another", derived from Jean de La Fontaine's fable "The Monkey and the Cat"

Arts and entertainment

 * Catspaw (rock opera), a 1974 Australian rock musical written by Dorothy Hewett
 * Catspaw (TV series), a 1978 Australian series
 * "Catspaw" (Star Trek: The Original Series), a television episode
 * The Cat's-Paw, a 1934 film with Harold Lloyd
 * Cat's Paw (1959 film), a Looney Tunes cartoon
 * Catspaw (comics), April Dumaka, a superhero character in DC Comics
 * Cat's Paw (adventure), for the role-playing game Marvel Super Heroes
 * Catspaw, a 1988 science fiction novel by Joan D. Vinge
 * Catspaw, a 2021 album by Matthew Sweet

Nature

 * Cat's Paw Mussel, one of a few species of Epioblasma mussels
 * Catspaw, informal name of some species of the plant Anigozanthus (Haemodoraceae)
 * Cat's Paw Nebula or Bear Claw Nebula, common names for NGC 6334
 * Cat's paw (wave), in Earth sciences, a pattern of shallow ripples (capillary waves) on the surface of water

Technology

 * Cat's paw (knot), a knot used for connecting a rope to an object
 * Cat's paw (tool), a hand tool for extracting nails

title: Cat's paw