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helene_thygesen
Affy SNP-chip metadata - how to read the probe sequences?
I have Affymetrix SNP-chip (250 K genomic) data. For each gene there are 56 probes =7 "quartets" (windows)*AB*PMMM*SenseAS. The information in the accompagnying CDF/TXT file looks like
SNP_A-1780520 rs16994928 ggatagtgttgacctc[A/G]agtacaggtttcaaaa 496 // 47873735 // 47874230 0.0 0.11 0.0
ProbeSetID Chromosome Expr1002 PhysicalPosition AlleleA dbSNPRSID
SNP_A-1780520 20 47874178 47874178 A rs16994928
I need to intepret these meta-data in terms of the probe sequences. In particular, where in the ggatagtgttgacctc[A/G]agtacaggtttcaaaa string are the seven quartets and how does the MM probe difer from PM probe
1 AnswerBiology1 decade agoWhy were they so big?
Recently, an amphibian-fish (or whatever it should be called) was found in Alaska. It (or one of its cousins) could be the ancestor of all terristrial vertebrates.
What pussels me is the size of the creature. 3 meter. Today, fish that live part of their life on land or just incidently crawl on land are much smaller.
When animals evolve into big forms it has usually to do with predator/prey interaction. I don't see how this could apply to the first pioneers.
Maybe they came in all sizes and it's just that big fossils are mor likely to be found? Or maybe life was less advanced so organs like lungs could not be miniaturized? Any thoughts?
4 AnswersBiology1 decade agoWhat is a flat-space property?
I asked if the rest mass of a photon is still zero in non-vacuum, where it's velocity is less than c. I got the answer that it is indeed still zero, because the length of the 4-vector (E/c,px,py,pz) is zero. And because this is a flat space property it's easily generalised to other coupled fields to describe non-vacuum situations: the result still holds. Now my problem is that I don't know what a flat-space property is, i.o.w. why the four-vector is still zero.
4 AnswersPhysics1 decade agoRelativistic/rest mass of photon in non-vacuum?
A photon has zero rest mass yet positive relativistic mass. This is possible only if v=c. Yet this only holds in vacuum. I can imagine that the energy budget holds if light is seen as waves, but still there should be a solution to this paradox. Is the rest mass positive in non-vacuum?
2 AnswersPhysics1 decade ago
