17 March 2018

How to read a scientific paper

Sorry for being a bit late with this post. I’m preparing a grant proposal, and boy that needs loads of work to make it good enough.
This artist’s impression shows how the Milky Way galaxy would look seen from almost edge on and from a very different perspective than we get from the Earth. The central bulge shows up as a peanut shaped glowing ball of stars and the spiral arms and their associated dust clouds form a narrow band.

Anyway, back to how to read a scientific paper.
I will share with you the tips I got when I started grad school.
Every scientific paper is written so that average grad student can understand it. Of course, this means that whoever wrote it expects a reader to have at least the basic knowledge of the subject from the university level, i.e. Bachelor degree.
So, if you are trying to read the paper outside of your background count more time because you’ll have to consult either books or the internet to learn about the basic terms.


All four options from my poll got the same number of votes, so I picked article Discovery of Gamma-Ray Emission from the X-shaped Buldge of the Milky Way. And here are the links where you can find the whole article for free and version that went to Nature.
I chose this one as an example because is a relatively fresh publication, Nature announced it on 12th March 2018. And it is outside of my area of expertise, but close enough that I do not have to dig for the Astrophysics and Physics books to understand it.


A long time ago, when I was part of Max Planck International School, I got directions on how to read the paper. Grad students are expected to read loads of papers to learn about the subject, so they have to do some kind of triage to decide is the paper worth for their work or not. And triage is done in the following steps:
  1. Read an abstract.
  2. Look at the images and read captions.
  3.  Read conclusion/summary.
  4.  Read the paper in details.
Of course, these steps are meant to make an overall reading of papers efficient, so that student can learn fast what is necessary to perform the research. One should proceed with all 4 steps only if each previous showed the paper is useful for the project.
I'm not kidding about a need for efficiency. I had to read more than 300 different papers during my thesis work.


So, the first step. Please download the paper yourself and try to read abstract, due to copyrights I cannot cite it here.
Here is what I got from reading the abstract. In short, abstract says scientists discovered that excess gamma rays are spatially correlated with places in a galaxy where there are loads of stars.
Abstract also implies the importance of this work. This research basically says that extra gamma rays earlier observed are not connected with the dark matter as previous researcher thoughts.
So let us go bit by bit. The abstract is a complex structure that has to mention all parts of the paper in one or two sentences.
This particular one mentioned the instrument used in this research, Fermi Gamma-Ray Large Area Telescope.
Then abstract mention motivation for the research--learning about the dark matter through the gamma rays.
Also, it mentions what analysis scientists used on the data, in this case, hydrodynamical modeling.
States results, the spatial correlation between gamma rays and locations with extra stars. Spatially correlated means scientists found both gamma rays and groups of stars in the same place.
And finishes with the conclusion - nope, extra gamma rays have nothing to do with dark matter, sorry folks.
To be honest, up to this point I did not even know that extra gamma rays might be connected with dark matter, but I do know that dark matter is some kind of the hot topic. Dark matter tickles interest of many scientists.
Another honest disclosure. I do not really understand what the dark matter is supposed to be. I know it is some kind of concept introduced to explain what is going on in our universe, you know, explain why the galaxies behave as there is more matter in them than we can observe. Like galaxies are heavier than they should be based on a number of stars we observed. See, when I had my short astronomy course, during my studies for BS in Physics, dark matter was barely mentioned in my short astronomy course. Actually, my teacher gave us a wrong explanation saying that dark matter is all that dust and planets we cannot see. Which is not exactly true.
So, in a way, we will try to understand this paper together.

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