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December 23 Information
The † symbol in biological nomenclature
The standard orthographical dagger symbol when not identical in form to a cross.
In the course of editing, I've come across sources that place the † symbol in front of the name of an order or clade or family or genus in the biological nomenclature for organisms. Example: †Name. Here's a link to one such source:
[1]. I've been looking for a definition of what the symbol means, and have been coming up blank. Can anyone point me to its meaning? Thanks. --
Tryptofish (
talk)
01:40, 23 December 2017 (UTC)reply
Yes, it means extinct, and the
dagger symbol (with illustration) is also used (I don't see that in our markup palette) which is an inverted dagger that looks like a cross, except that the top is thick, like a dagger's handle.
μηδείς (
talk)
02:47, 23 December 2017 (UTC)reply
I have added the dagger as a png file so one can see the normal figure when it is not printed identically to a cross, as often occurs in non-serif fonts.
μηδείς (
talk)
17:06, 23 December 2017 (UTC)reply
??obviously I would know that article, you sarcastic discourteous linker. Doesn't answer question, but it could mislead others into thinking the answer was at that article. — Preceding
unsigned comment added by
64.134.232.149 (
talk) 04:32, 23 December 2017 (UTC)
Hey I wrote the above angry reply and I'm really sorry for being like that. Just really hyper and paranoid yesterday. By the way though, my device won't let me do brackets for linking or even girlies for signing. Sorry again! — Preceding curly is spellchecked into girlies!
unsigned comment added by
96.82.242.226 (
talk)
23:36, 23 December 2017 (UTC)reply
Yes; they're intended as a courtesy to other editors, not to the OP, who should arguably have made the link themself. An alternative would be to Wikilink the words in the OP's own text, but this would violate the convention that we don't alter another's post in any way. {The poster formerly known as 87.81.230.195}
90.220.212.173 (
talk)
09:12, 23 December 2017 (UTC)reply
There's nothing wrong with modifying the header to include the link, that's the best place for it anyway, and headers are not the poster's property, per MOS.
μηδείς (
talk)
16:34, 23 December 2017 (UTC)reply
There should be someneutron electric dipole moment, though technically that would be a
dispersion force at the
Van der Waals radius I suppose.... or it would be, if nucleus-nucleus "noncovalent bonds" were a thing. Hmmm. Also, while in theory
molecules are defined by electrons, so no electrons means... I suppose there is some very small chance that an electron + positron (
virtual pair) exist near a pair of neutrons. You might also say the neutrons would be brought together a little by
Casimir effect, which is also a virtual particle effect ... but the metal plates in a usual Casimir effect aren't normally defined as a molecule. But what if the virtual particles can exist in real orbitals for a moment, is that Casimir effect or something else? No "orbitals" in a Casimir effect that I know of! Obviously I'm in no position to answer this but I hope the links/ideas might be a starting point for further consideration. But I'm a little off topic for the sort of nuclear interactions you're most interested in. A search for dineutron observed pulls up a bunch of interesting papers like
[2] but I'm not the one to rate their quality/believability. P.S. neutrons have spin 1/2, so there should be two
nuclear isomers of any given "dineutron", one with spin 0 and one with spin +-1/2; are both accounted for?
Wnt (
talk)
14:51, 23 December 2017 (UTC)reply
To be fair, He2 is not so much a molecule as a
van der Waals molecule. MO theory, or at least as used for He2, is focused on covalent bonding; which is a reasonable approximation for most "normal" molecules, but for something like He2 where no covalent bonding is possible and only the van der Waals interaction is feasible, it is clearly not the best approach. A similar idea is not inconceivable; the dineutron
does become stable on the surface of neutron-rich nuclei (a pretty direct quote, but there's no sensible way to paraphrase this – it's a footnote to the paper, which is itself pretty interesting, being about the consequences a stable dineutron would have on BBN).
Double sharp (
talk)
05:12, 24 December 2017 (UTC)reply
Hmmm, this says "The dineutron, a member of the nucleon-nucleon isospin triplet, is a spin singlet". I would think that means that dineutrons are defined as made up of neutrons with opposite spins, and the ones with same-sign spins are called something else? At best guess, those others would be less stable since spins ordinarily like to pair, so it may be something more obscure? If we can clinch this we might be able to upgrade our article.
Wnt (
talk)
02:09, 25 December 2017 (UTC)reply
15-1. Solve the Lorentz transformation for x,y,z,t in terms of x' , y' , z' , t'.
— R. B. Leighton , Feynman Lectures on Physics. Exercises
It seems that paradox described in previous question on 17.12.2017 is that the observers can not see both ends of the ruler at the same time. My new question is: Is it possible to adjust clocks such that at coordinates x=x'=0 we have readings on clocks t=t'=1? From Lorenz transformation it is impossible, but why can't we adjust clocks by our wish in single point of space ?
Username160611000000 (
talk)
12:34, 30 December 2017 (UTC)reply
Weird space launch shot
There was a news story about a space launch
[3] that Los Angeles citizens reportedly thought was aliens arriving.
[4] Now I assume this is a bit of "product placement"; I would be flabbergasted if some of the photographers were not both paid and prepared in advance with an ephemeris. Even so ... how did a space launch generate this kind of blimp-like "structure" in the sky, with a bright glowing bit in the middle? I mean, if this was a
shock wave it shouldn't have outrun the rocket ... I'd think... also, if it was that powerful a shock wave, why didn't it create a huge boom that would have been commented on in the article?
Wnt (
talk)
14:39, 23 December 2017 (UTC)reply
This was a
Falcon 9 launch. These are a lot more complicated than normal launches. After stage separation, the first stage quickly flips around through almost 180 degrees with nitrogen thrusters, and reignites 1-3 engines to cancel the downrange speed for lading (this particular stage didn't actually do a full landing, but still went through these phases). This means that the engine plumes of both upper and lower stage are firing 'into each other', which lead to all sorts of complex interactions you don't see in normal launches. The bright glowing bit is the first stage, either thruster firings, or most likely the boostback burn. Don't see why you assume there is product placement? Everybody carries a camera with them in their pockets these days. Only need <<0.1% of people to see it to get multiple videos. Easy enough, as the trajectory is visible from a major population centre.
Fgf10 (
talk)
16:14, 23 December 2017 (UTC)reply
Wnt, you are so gullible. Once again you have fallen for the CIA's propaganda. This was not a failed private launch or a publicity stunt! It was a NASA first-stage booster launching Stephen Paddock to rendezvous with last week's Earth-grazing asteroid, where he'll live until 'Oumuamua returns to defeat the
Trump Dynasty rulers of the Planets of the Solar Federation in 2112.
μηδείς (
talk)
16:31, 23 December 2017 (UTC)reply
Vonnegut, Trump, Tesla and Gorsuch? Of course that piece is as coherent as the ramblings of a schizophrenic in a full psychotic break. I need an Excedrin.
μηδείς (
talk)
19:58, 23 December 2017 (UTC)reply
The time and date of this launch was publicized over two month in advance.
Here is Iridium's press release from 19 October. Given the clear forecast and the launch time scheduled for shortly after sunset, space enthusiast boards were abuzz with expectations of a spectacular display, though the actual event exceeded most already high expectations. If the local media failed to discuss the launch in advance and suggest that local residents consider checking out the show, then they dropped the ball. --
ToE20:00, 23 December 2017 (UTC)reply
Hey, the local news here has lots of very important car chases to cover! Also who pays any attention to the local news anymore? We all get our news from Facebook, which takes care to not disturb us with anything outside of our personal bubbles. --
47.157.122.192 (
talk)
07:23, 24 December 2017 (UTC)reply
Breaking news: The crew of an arcraft have been offerd emotional and psychological support to help them come to terms with an inccident where their arcraft recently made physical contact with a UFO over Scadinavior.
Photo of damage.. The Inrernational Civil Aviation Authority has issued a statment, to the effect, that in order to avoid widespead concern and panic, it is not going to comment just yet untill all radar images of the collition have been anylised but assures the public that this UFO possesed no danger to the general public as it never came lower than roof top level.
Aspro (
talk)
20:17, 23 December 2017 (UTC)reply
I stand currected. I hefe-a a beet ouff truouble translating zee language-a ouff Swedes und Turnips intu Ingleesh. ispeceelly after sampling their
Akvavit.. Bork Bork Bork!
Aspro (
talk)
13:12, 24 December 2017 (UTC)reply
As a So Cal resident, every time anything is launched from Vandenberg you have people freaking out. Breaking news: a lot of people are dumb and/or ignorant. --
47.157.122.192 (
talk)
07:23, 24 December 2017 (UTC)reply
Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a
transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the
current reference desk pages.
December 23 Information
The † symbol in biological nomenclature
The standard orthographical dagger symbol when not identical in form to a cross.
In the course of editing, I've come across sources that place the † symbol in front of the name of an order or clade or family or genus in the biological nomenclature for organisms. Example: †Name. Here's a link to one such source:
[1]. I've been looking for a definition of what the symbol means, and have been coming up blank. Can anyone point me to its meaning? Thanks. --
Tryptofish (
talk)
01:40, 23 December 2017 (UTC)reply
Yes, it means extinct, and the
dagger symbol (with illustration) is also used (I don't see that in our markup palette) which is an inverted dagger that looks like a cross, except that the top is thick, like a dagger's handle.
μηδείς (
talk)
02:47, 23 December 2017 (UTC)reply
I have added the dagger as a png file so one can see the normal figure when it is not printed identically to a cross, as often occurs in non-serif fonts.
μηδείς (
talk)
17:06, 23 December 2017 (UTC)reply
??obviously I would know that article, you sarcastic discourteous linker. Doesn't answer question, but it could mislead others into thinking the answer was at that article. — Preceding
unsigned comment added by
64.134.232.149 (
talk) 04:32, 23 December 2017 (UTC)
Hey I wrote the above angry reply and I'm really sorry for being like that. Just really hyper and paranoid yesterday. By the way though, my device won't let me do brackets for linking or even girlies for signing. Sorry again! — Preceding curly is spellchecked into girlies!
unsigned comment added by
96.82.242.226 (
talk)
23:36, 23 December 2017 (UTC)reply
Yes; they're intended as a courtesy to other editors, not to the OP, who should arguably have made the link themself. An alternative would be to Wikilink the words in the OP's own text, but this would violate the convention that we don't alter another's post in any way. {The poster formerly known as 87.81.230.195}
90.220.212.173 (
talk)
09:12, 23 December 2017 (UTC)reply
There's nothing wrong with modifying the header to include the link, that's the best place for it anyway, and headers are not the poster's property, per MOS.
μηδείς (
talk)
16:34, 23 December 2017 (UTC)reply
There should be someneutron electric dipole moment, though technically that would be a
dispersion force at the
Van der Waals radius I suppose.... or it would be, if nucleus-nucleus "noncovalent bonds" were a thing. Hmmm. Also, while in theory
molecules are defined by electrons, so no electrons means... I suppose there is some very small chance that an electron + positron (
virtual pair) exist near a pair of neutrons. You might also say the neutrons would be brought together a little by
Casimir effect, which is also a virtual particle effect ... but the metal plates in a usual Casimir effect aren't normally defined as a molecule. But what if the virtual particles can exist in real orbitals for a moment, is that Casimir effect or something else? No "orbitals" in a Casimir effect that I know of! Obviously I'm in no position to answer this but I hope the links/ideas might be a starting point for further consideration. But I'm a little off topic for the sort of nuclear interactions you're most interested in. A search for dineutron observed pulls up a bunch of interesting papers like
[2] but I'm not the one to rate their quality/believability. P.S. neutrons have spin 1/2, so there should be two
nuclear isomers of any given "dineutron", one with spin 0 and one with spin +-1/2; are both accounted for?
Wnt (
talk)
14:51, 23 December 2017 (UTC)reply
To be fair, He2 is not so much a molecule as a
van der Waals molecule. MO theory, or at least as used for He2, is focused on covalent bonding; which is a reasonable approximation for most "normal" molecules, but for something like He2 where no covalent bonding is possible and only the van der Waals interaction is feasible, it is clearly not the best approach. A similar idea is not inconceivable; the dineutron
does become stable on the surface of neutron-rich nuclei (a pretty direct quote, but there's no sensible way to paraphrase this – it's a footnote to the paper, which is itself pretty interesting, being about the consequences a stable dineutron would have on BBN).
Double sharp (
talk)
05:12, 24 December 2017 (UTC)reply
Hmmm, this says "The dineutron, a member of the nucleon-nucleon isospin triplet, is a spin singlet". I would think that means that dineutrons are defined as made up of neutrons with opposite spins, and the ones with same-sign spins are called something else? At best guess, those others would be less stable since spins ordinarily like to pair, so it may be something more obscure? If we can clinch this we might be able to upgrade our article.
Wnt (
talk)
02:09, 25 December 2017 (UTC)reply
15-1. Solve the Lorentz transformation for x,y,z,t in terms of x' , y' , z' , t'.
— R. B. Leighton , Feynman Lectures on Physics. Exercises
It seems that paradox described in previous question on 17.12.2017 is that the observers can not see both ends of the ruler at the same time. My new question is: Is it possible to adjust clocks such that at coordinates x=x'=0 we have readings on clocks t=t'=1? From Lorenz transformation it is impossible, but why can't we adjust clocks by our wish in single point of space ?
Username160611000000 (
talk)
12:34, 30 December 2017 (UTC)reply
Weird space launch shot
There was a news story about a space launch
[3] that Los Angeles citizens reportedly thought was aliens arriving.
[4] Now I assume this is a bit of "product placement"; I would be flabbergasted if some of the photographers were not both paid and prepared in advance with an ephemeris. Even so ... how did a space launch generate this kind of blimp-like "structure" in the sky, with a bright glowing bit in the middle? I mean, if this was a
shock wave it shouldn't have outrun the rocket ... I'd think... also, if it was that powerful a shock wave, why didn't it create a huge boom that would have been commented on in the article?
Wnt (
talk)
14:39, 23 December 2017 (UTC)reply
This was a
Falcon 9 launch. These are a lot more complicated than normal launches. After stage separation, the first stage quickly flips around through almost 180 degrees with nitrogen thrusters, and reignites 1-3 engines to cancel the downrange speed for lading (this particular stage didn't actually do a full landing, but still went through these phases). This means that the engine plumes of both upper and lower stage are firing 'into each other', which lead to all sorts of complex interactions you don't see in normal launches. The bright glowing bit is the first stage, either thruster firings, or most likely the boostback burn. Don't see why you assume there is product placement? Everybody carries a camera with them in their pockets these days. Only need <<0.1% of people to see it to get multiple videos. Easy enough, as the trajectory is visible from a major population centre.
Fgf10 (
talk)
16:14, 23 December 2017 (UTC)reply
Wnt, you are so gullible. Once again you have fallen for the CIA's propaganda. This was not a failed private launch or a publicity stunt! It was a NASA first-stage booster launching Stephen Paddock to rendezvous with last week's Earth-grazing asteroid, where he'll live until 'Oumuamua returns to defeat the
Trump Dynasty rulers of the Planets of the Solar Federation in 2112.
μηδείς (
talk)
16:31, 23 December 2017 (UTC)reply
Vonnegut, Trump, Tesla and Gorsuch? Of course that piece is as coherent as the ramblings of a schizophrenic in a full psychotic break. I need an Excedrin.
μηδείς (
talk)
19:58, 23 December 2017 (UTC)reply
The time and date of this launch was publicized over two month in advance.
Here is Iridium's press release from 19 October. Given the clear forecast and the launch time scheduled for shortly after sunset, space enthusiast boards were abuzz with expectations of a spectacular display, though the actual event exceeded most already high expectations. If the local media failed to discuss the launch in advance and suggest that local residents consider checking out the show, then they dropped the ball. --
ToE20:00, 23 December 2017 (UTC)reply
Hey, the local news here has lots of very important car chases to cover! Also who pays any attention to the local news anymore? We all get our news from Facebook, which takes care to not disturb us with anything outside of our personal bubbles. --
47.157.122.192 (
talk)
07:23, 24 December 2017 (UTC)reply
Breaking news: The crew of an arcraft have been offerd emotional and psychological support to help them come to terms with an inccident where their arcraft recently made physical contact with a UFO over Scadinavior.
Photo of damage.. The Inrernational Civil Aviation Authority has issued a statment, to the effect, that in order to avoid widespead concern and panic, it is not going to comment just yet untill all radar images of the collition have been anylised but assures the public that this UFO possesed no danger to the general public as it never came lower than roof top level.
Aspro (
talk)
20:17, 23 December 2017 (UTC)reply
I stand currected. I hefe-a a beet ouff truouble translating zee language-a ouff Swedes und Turnips intu Ingleesh. ispeceelly after sampling their
Akvavit.. Bork Bork Bork!
Aspro (
talk)
13:12, 24 December 2017 (UTC)reply
As a So Cal resident, every time anything is launched from Vandenberg you have people freaking out. Breaking news: a lot of people are dumb and/or ignorant. --
47.157.122.192 (
talk)
07:23, 24 December 2017 (UTC)reply