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How is coal and oil formed and what is the difference —Preceding unsigned comment added by 203.102.161.75 ( talk) 00:45, 17 May 2008 (UTC)
As a layman, I don't understand how any species can emerge in more than one place or zone of places. My question is: under the multiregional model, how did genetic mutations become dominant traits in many different places, leading to speciation at different times and places? Are they suggesting that proto-members of the antecedent species had dormant DNA mutations, which in many different places and times became more successful because of similar environmental pressures? And that after the dormant DNA carried by the antecedent species spread out, it eventually flowered in different places in the same way? While still enabling successful breeding between members of the different groups constituting the new species, when eventually the geographically diverse people crossed paths again?
I guess the broader question is simply: Can any species emerge at different times and in widely-spaced locations? —Preceding unsigned comment added by 4.182.36.205 ( talk) 04:59, 17 May 2008 (UTC)
TY for this.
yes, I've read the source you refer to. Multiregional origin of modern humans
you wrote: "DNA isn't "dormant" per se, but genetic differences may not provide selective advantages until they "come into contact" the the right environment."
I meant to imply that point, in my badly written question. (i.e., I understand that.)
I'll read "convergent evolution."
It still seems like special pleading to me. —Preceding unsigned comment added by 4.182.36.205 ( talk) 07:52, 17 May 2008 (UTC)
Convergent evolution, as I read it, refers to traits, not species -- of course, highly similar traits may evolve in widely divergent places and times ... but different species? I don't see how it makes sense. —Preceding unsigned comment added by 4.182.36.205 ( talk) 07:56, 17 May 2008 (UTC)
and, WADR (with all due respect!), the article titled "hybrid-origin" is ridiculous and based on the fanciful notions of one S. Gooch, supported by no evidence ... —Preceding unsigned comment added by 4.182.36.205 ( talk) 08:57, 17 May 2008 (UTC)
Other than Crystallography, How Geology pictures in in Material science? 59.95.69.97 ( talk) 09:35, 17 May 2008 (UTC)
Is there some medical disadvantage in watching an old tv (with cathode ray tube) as compared with a new flat screen tv? Milk Float 09:48, 17 May 2008 (UTC)
How is forest a habitat? 117.99.32.175 ( talk) 10:29, 17 May 2008 (UTC)
In the first reference sited by the article on spinosad there is the following statement "DO NOT DISTRIBUTE THIS TECHNICAL BULLETIN IN THE STATE OF NEW YORK." What is the reason behind this statement? 71.100.14.205 ( talk) 14:58, 17 May 2008 (UTC)
how to find the rate of substitution of different haloalkanes?? —Preceding unsigned comment added by Danielezzat9654437047 ( talk • contribs) 18:02, 17 May 2008 (UTC)
it's not my homework!!!! i have three samples and all i know about them is that they are haloalkenes!!!! how can i differentiate between them???? I've thought of adding sodium hydroxide but the problem is they all turn to alcohols i need a way to differentiate between them!!! —Preceding unsigned comment added by Danielezzat9654437047 ( talk • contribs) 20:45, 17 May 2008 (UTC)
I need an experiment based on the isomeric halogenoalkanes with the formula C4H9BR reacting with water!!!! Plus i don't have any of this stuff, i can't perform a chromatography and i don't have any of the measurement equipment you just mentioned.When haloalkanes react with NaOH they release halides which are easy to identify if passed through silver nitrate. But i need to identify whether the haloalkane is primary, secondary or tertiary. And i think the only way to do so is by measuring the rate of the substitution of the halide. (There is no need to attempt a fractionation my samples are single components).
Danielezzat9654437047 (
talk)
03:29, 18 May 2008 (UTC)
What's it called when a bunch of water molecules gather round an entity as in MgCl2*6H2. We did something about it in A level chemistry but I guess those brain-cells haven't seen lot of use since. ---- Seans Potato Business 18:56, 17 May 2008 (UTC)
Hello,
sorry if this belongs in Humanities or Mathematics. One sometimes reads about "the demographic barycenter". It is used to denote where most people live in a certain region or state. But is this well defined? Has someone ever tried it?
My definition would be : make a vector (from the center of the earth ) pointing at an individual, add them all up and divide by the number of people in the region you want to consider.(note that we would be also taking into account some differences in height). Or would this not be suitable?
Has someone ever used a definition like this? Are there articles/websites/books actually providings maps to illustrate where the "demographic barycenter" is?
Many thanks,
Evilbu ( talk) 19:13, 17 May 2008 (UTC)
Science desk | ||
---|---|---|
< May 16 | << Apr | May | Jun >> | May 18 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
How is coal and oil formed and what is the difference —Preceding unsigned comment added by 203.102.161.75 ( talk) 00:45, 17 May 2008 (UTC)
As a layman, I don't understand how any species can emerge in more than one place or zone of places. My question is: under the multiregional model, how did genetic mutations become dominant traits in many different places, leading to speciation at different times and places? Are they suggesting that proto-members of the antecedent species had dormant DNA mutations, which in many different places and times became more successful because of similar environmental pressures? And that after the dormant DNA carried by the antecedent species spread out, it eventually flowered in different places in the same way? While still enabling successful breeding between members of the different groups constituting the new species, when eventually the geographically diverse people crossed paths again?
I guess the broader question is simply: Can any species emerge at different times and in widely-spaced locations? —Preceding unsigned comment added by 4.182.36.205 ( talk) 04:59, 17 May 2008 (UTC)
TY for this.
yes, I've read the source you refer to. Multiregional origin of modern humans
you wrote: "DNA isn't "dormant" per se, but genetic differences may not provide selective advantages until they "come into contact" the the right environment."
I meant to imply that point, in my badly written question. (i.e., I understand that.)
I'll read "convergent evolution."
It still seems like special pleading to me. —Preceding unsigned comment added by 4.182.36.205 ( talk) 07:52, 17 May 2008 (UTC)
Convergent evolution, as I read it, refers to traits, not species -- of course, highly similar traits may evolve in widely divergent places and times ... but different species? I don't see how it makes sense. —Preceding unsigned comment added by 4.182.36.205 ( talk) 07:56, 17 May 2008 (UTC)
and, WADR (with all due respect!), the article titled "hybrid-origin" is ridiculous and based on the fanciful notions of one S. Gooch, supported by no evidence ... —Preceding unsigned comment added by 4.182.36.205 ( talk) 08:57, 17 May 2008 (UTC)
Other than Crystallography, How Geology pictures in in Material science? 59.95.69.97 ( talk) 09:35, 17 May 2008 (UTC)
Is there some medical disadvantage in watching an old tv (with cathode ray tube) as compared with a new flat screen tv? Milk Float 09:48, 17 May 2008 (UTC)
How is forest a habitat? 117.99.32.175 ( talk) 10:29, 17 May 2008 (UTC)
In the first reference sited by the article on spinosad there is the following statement "DO NOT DISTRIBUTE THIS TECHNICAL BULLETIN IN THE STATE OF NEW YORK." What is the reason behind this statement? 71.100.14.205 ( talk) 14:58, 17 May 2008 (UTC)
how to find the rate of substitution of different haloalkanes?? —Preceding unsigned comment added by Danielezzat9654437047 ( talk • contribs) 18:02, 17 May 2008 (UTC)
it's not my homework!!!! i have three samples and all i know about them is that they are haloalkenes!!!! how can i differentiate between them???? I've thought of adding sodium hydroxide but the problem is they all turn to alcohols i need a way to differentiate between them!!! —Preceding unsigned comment added by Danielezzat9654437047 ( talk • contribs) 20:45, 17 May 2008 (UTC)
I need an experiment based on the isomeric halogenoalkanes with the formula C4H9BR reacting with water!!!! Plus i don't have any of this stuff, i can't perform a chromatography and i don't have any of the measurement equipment you just mentioned.When haloalkanes react with NaOH they release halides which are easy to identify if passed through silver nitrate. But i need to identify whether the haloalkane is primary, secondary or tertiary. And i think the only way to do so is by measuring the rate of the substitution of the halide. (There is no need to attempt a fractionation my samples are single components).
Danielezzat9654437047 (
talk)
03:29, 18 May 2008 (UTC)
What's it called when a bunch of water molecules gather round an entity as in MgCl2*6H2. We did something about it in A level chemistry but I guess those brain-cells haven't seen lot of use since. ---- Seans Potato Business 18:56, 17 May 2008 (UTC)
Hello,
sorry if this belongs in Humanities or Mathematics. One sometimes reads about "the demographic barycenter". It is used to denote where most people live in a certain region or state. But is this well defined? Has someone ever tried it?
My definition would be : make a vector (from the center of the earth ) pointing at an individual, add them all up and divide by the number of people in the region you want to consider.(note that we would be also taking into account some differences in height). Or would this not be suitable?
Has someone ever used a definition like this? Are there articles/websites/books actually providings maps to illustrate where the "demographic barycenter" is?
Many thanks,
Evilbu ( talk) 19:13, 17 May 2008 (UTC)