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There are several papers which are using following formula (as shown in the picture) to calculate the dust mass (Md) of the dusty environments such as Nebula, loops etc in the ISM. The expression for dust mass shows that it depends on grain size, grain density and grain emissivity, here, for IRAS Survey, grain size = 0.1 micron, density = 1000 kg/m3 and emissivity = 0.0010 for 100 micron, respectively, are used. Are these constants same for AKARI and WISE survey too? OR, are there any other methods for the dust mass calculation using AKARI and WISE data? I would be very much happy to get your valuable suggestions. Thank you :)
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The grain size, density and emissivity are not properties of the data/telescope (IRAS, WISE or AKARI), but of the physical objects you want to study. Hence, deciding which parameters to use is complex and must come from your knowledge of these objects. Have a look on how these parameters were derived from IRAS data - what kind of objects, assumptions, conditions? If they roughly can be applied to the objects you want to study with AKARI, then you can justify using the same parameters. If your objects are completely different then you need to somehow derive or find a different set of parameters (or at least a range of possible values).
Good luck,
Michał
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I want to know how the composition of The Galactic Cosmic Rays in Interstellar Medium would be affected as the Universe evolves and its metalicity changes. The amount of heavy metals must increase and so I am looking for quantitative values for it.
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THE ASTROPHYSICAL JOURNAL, 499 :735-745, 1998 June 1
GALACTIC COSMIC RAYS AND THE EVOLUTION OF LIGHT ELEMENTS
Martin Lemoine and Co. Department of Astronomy and Astrophysics, Enrico Fermi Institute, University of Chicago.
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I am working an a project which requires me to know the exact total amount of GCR flux between 10MeV to 1GeV. There are many papers on GCR flux but they only talk about flux at some specific energy but not the total flux of GCR.
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McCracken, K. G., and J. Beer (2014),
Comparison of the extended solar
minimum of 2006–2009 with the
Spoerer, Maunder, and Dalton Grand
Minima in solar activity in the past,
J. Geophys. Res. Space Physics, 119,
2379–2387, doi:10.1002/2013JA019504.
I think Dr. McCracken can help you
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I am working on the Ethanimine formation in the Interstellar medium by reaction CH2+CH2NH---->CH3CHNH. CH2 is taken in both singlet and triplet form. when I add water molecule in reaction complex for simulation of ice. sometimes I get transition state which has lower energy than reaction complex(RC). I want to know the physical meaning of that kind of transition state and how to find rate coefficient for these reactions.  
One more question , is "Hammond–Leffler postulate"  is applicable in Interstellar medium? Can I use it to verify my TS structure is correct or not?
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The reactions with intermediate complexes and submerges barriers are my favourite topic.
You terminology is wrong. TS is not equal with the barrier. In a quantum chemical calculation you get only raw energy  of barriers or local minima. These quantities are related to the topology of the potential energy surface (PES is calculated in Qchem). Transition state is a dividing surface in the phase space that separates the reactants and products. In conventional transition state theory (TST) the transition state is located at the barrier (but it is not necessary to locate here). Sometimes there is no barrier, or the barrier is submerged. Then it is not trivial where is (or even exist) the transition state regarding to the potential energy surface.
If you can not find  barrier, or you find a submerged barrier....your elementary reaction is  guided by attractive forces. The potential energy surface guides the reactants to each others. This guiding effect can be very efficient at low temperatures (like in space). If you has a submerges barrier, you must find a van der Waals complex before your submerges barrier. In this case the potential energy surface is attractive, but there are a chance to the formation of this complex. If this complex lives long, you can predict the rate of the reaction with statistical rate theories (RRKM, SACM, special version of TST (see Klippenstein's double TST (2TST)  version).
According to the attractive potential energy surface you may get negative activation energy for the reaction (activation energy is not the height of the barrier, it is the local slope of the Arrhenius plot!). In some case the sign of the activation energy can be changed. At low temperatures the activation energy is negative, but at high temperature it's value is positive.
And the answers for the other questions:
Can I use it to verify my TS structure is correct or not?
You can verify only the goodness of your barrier with a frequency calculation at the barrier. The saddle point  is correct, if you have ONLY one imaginary frequency, the others are real.
...how to find rate coefficient for these reactions?"
you can use RRKM theory for the vdW complex. If you are an expert in TST calcualtion you can use Klippenstein's 2TST or Krasnoperov's modified TS theroy.
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How stable are the living systems in regards to isotopic activity is perhaps an old time question.
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Dmitry Grodzinsky, with all due respect, what exactly do you mean by "In the cell, there are no energy fields and interactions that could provide for transmutation of atoms." ? Please explain, extrapolate.
An isotope is an entity that "popular speaking" it has an "internal clock", that after some given time, for instance the isotope 14C (carbon-14), after 5715 (5730) years will be half in quantity. Sure, the atoms are "circulating", changing with fresh ones (from air, CO2 etc) in the case of a living cell, but we have no guaranty the all "old atoms" leave the cells and all C atoms are new, so that apparently the quantity remains almost the same, but nothing guaranties us that a given isotope ( example 14C ) can not transmute while being located in a cell (alive) . It simply it came its time to transmute, due to its internal clock (I call it). No much is being known about the mechanism and the 1/2 time. It is all based on some statistics, assumptions, and mathematical calculations that often prove to be incorrect.
Nothing will stop a given isotope, in a living cell or in a body without any life, to transmute into an other atom ! Transmutation probably can be accelerated or slow down, but they take place even at 0 Kelvin. Does it? It takes place in the interstellar space, far from any heat.
Energy , of all different kinds, is present everywhere. I would say, and sure you agree with me, that energy is the ONLY thing that is found absolutely everywhere.
I personally see all existence as energy, mater being a form of energy's existence and we refer to mater for the purpose of communication only even in the case of intangible mater (but that's an other area, still not too far from our subject) .
Back to transmutation of isotopes: The energy is internal, within the atom (an isotope, that is like a bomb with internal clock) that at a certain time, for instance using the example of 14C, it will become 14N (nitrogen 14).
Nothing can stop an isotope to transmute, but external energies can possibly help it to transmute faster or slower, we do not know much about it.
On the other hand, since we are talking about external forces, an atom under the incidence of a cosmic ray (CR as external force), does not have any "protection" being connected with other atoms, being part of a small or large molecule. Again, as example, If a 14N atom is hit by a CR , strong enough, even so being at the Earth surface level or up at high altitude, it will become carbon-14.
Sure, the living cell it has the ability to adapt, self-repair, etc... still, this is what we are talking about here: What if the atom (Isotope)  transmutes while it has an active roll in the living cell ?
In the question I was not referring only to difference in mass or numbers of isotopes but rather the effect it has upon the cell's stability, function, future development, the transmutation of any given atom by either the "internal clock, internal forces" of the isotope (more likely) or, why not, the external forces due to CR of variety of energies , high, low, bombardment found and sea level, under ground, and surely much more at higher altitudes.
Thank you for your answer / participation , much more so you are so far the only person to answer the question being addressed exactly 5 years ago ( Dec 8, 2010).
Lets keep in personal contact please. The subject appears to be easy but in many ways it is tricky , I think.
Regards,
Adrian TW
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Is there a technical reason for not taking the data or the lack of data is due to the lack of interest in the information it might contain?
If you want to study dust disks around nearby stars, there is data from Herschel and Alma in infrared and radio range that enables spectroscopic studies of molecular transitions but there is no data taken at shorter wavelengths to study other kinds of processes. Why is that?
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I agree with you. In order to have emission in visible, in general you need high energy excitation which is usually scattered while in IR you are not seeing atomic but molecular transitions. IR radiation also suffers scattering but strong re-absorption aswell.
Since I am currently working in lanthanides, I was thinking about their unique property to be excited in IR and upconverting light i.e. emitting in visible upon IR excitation (and also in IR). Solid grains surely contain lanthanides but the problem is again scattering. On the other hand, lanthanides exposed directly, closer to the star can be excited both in visible and IR while they can transfer their radiation to farther neighbours in IR range. Those farther ions can again emit in both IR and visible and so on. This way, the energy is a bit more preserved than when you only have downconversion in which radiation is either re-absorbed at the same IR wavelength or re-emitted at lower energies. Would we be able to see anything of that I can not know since I haven't found the data.