this Magpie

The Internet’s Own Boy: The Story of Aaron Swartz

The film follows the story of programming prodigy and information activist Aaron Swartz. From Swartz’s help in the development of the basic internet protocol RSS to his co-founding of Reddit, his fingerprints are all over the internet. But it was Swartz’s groundbreaking work in social justice and political organizing combined with his aggressive approach to information access that ensnared him in…

Revert a git branch state to a previous commit

To reset index to former commit, where ‘26e05ffab‘ is the code associated with the old commit:

git reset 26e05ffab

Move pointer back to previous HEAD:

git reset --soft HEAD@{1}

Make a local commit of the whole revert:

git commit -m "Revert to commit 26e05ffab"

Update working copy to reflect the new commit

git reset--hard

Push the changes to remote branch:

git push origin [branch_name]

Push the…

Update to Fedora 22 and GNOME 3.16

To update to GNOME 3.16 with Fedora, it is first necessary to update to Fedora 22 from Fedora 21. To do this, first open a terminal and as root (i.e. sudo) and run the following commands:

sudo yum install fedora-upgrade  sudo fedora-upgrade

This will update to the next highest upgrade available. In this case it will update Fedora 20 to Fedora 21. Next run

sudo rpm --import…

Free Textbook: Ordinary and Partial Differential Equations

Finite Difference and Spectral Methods for Ordinary and Partial Differential Equations is a 325-page textbook  which was written during 1985-1994 and used in graduate courses at MIT and Cornell on the numerical solution of partial differential equations.

The book has not been completed, though half of it got expanded into Spectral Methods in MATLAB. Nevertheless, the part of it that is written is…

Energy at the Center of Mass: Proton-Proton Collisions

Recall the definition of $s$:

$$s=(p_a+p_b)^2 = p_a^2 + p_b^2 +2p_a\cdot p_b$$

Where $p_a$ and $p_b$ are the 4-momenta of each colliding proton. For head on collision of particles with same energy and momentum as is the case with proton-proton collisions

$p_a=(E_p,\underline{p})$ and $p_b=(E_p,-\underline{p})$

Where $E_p$ is the energy of the proton and $E_p$>> the protons mass, $m_p$

$$s=(E_p,…

A Crash Course in Einstein’s Relativity

From Zero to c in 60 Minutes with Ramamurti Shankar

Mark Twain once wrote: “It ain’t what you don’t know that gets you into trouble –it’s what you know for sure that just ain’t so.” So it was that, 109 years ago, some of humanity’s collective confusions were lifted when a 26-year-old Swiss patent clerk realized that something that everyone on Earth knew for sure was actually profoundly wrong.

Com…

The graph of stable elements is commonly referred to as the Band (or Belt) of Stability. At the higher end of the band of stability lies alpha decay, below is positron emission or electron capture, above is beta emissions and elements beyond the atomic number of 83 are unstable radioactive elements.

  Alpha decay is located at the top of the plotted line, because the alpha decay decreases the…

Beta decay is mediated by the weak force.

Beta Minus Decay ($\beta^-$)

During $\beta^-$ decay the weak interaction increases the atom’s number $Z$ by one which results in the emission of an election $e^-$ and an antineutrino, $\overline{\nu}_e$

$$ n \longrightarrow p+e^-+\overline{\nu}_e $$

At the most fundamental level the decay is from a down quark to an up quark with mediation being governed…

Properties of Leptons Particle/Antiparticle Symbol Charge S $L_e$ $L_{\mu}$ $L_{\tau}$ Mass $MeV/c^2$ Electron / Positron  $e^-/e^+$ −1/+1 1⁄2 +1/−1 0 0 0.511 Muon / Antimuon  $\mu^-/\mu^+$ −1/+1 1⁄2 0 +1/−1 0 105.7 Tau / Antitau  $\tau^-/\tau^+$ −1/+1 1⁄2 0 0 +1/−1 1777 Electron-neutrino / antineutrino  $\nu_e/\overline{\nu}_e$ 0 1⁄2 +1/−1 0 0 < 2.2×10−6 Muon-neutrino / antineutrino…

Java ATK Wrapper is a GNOME Project Module which is a implementation of ATK by using JNI technic. It converts Java Swing events into ATK events, and sends these events to ATK-Bridge.

The code is hosted at git.gnome.org

Magic Numbers in Nuclear Physics

Nuclei with even numbers of protons and neutrons have been found to be more stable by experiment. The magic numbers in protons nucleons or both have been shown to indicate greatest stability in nuclear isotopes. They are:

N = 2, 8, 20, 28, 50, 82, 126

Z =2, 8, 20, 28, 50, 82

Where Z means protons and N means neutrons

Quarks

up

down

charm

strange

top

bottom

Leptons

electron

muon

tau

electron-neutrino

muon-neutrino

tau-neutrino

The electron, muon and tau leptons have a charge of -1 whereas  neutrino leptons are neutral.

Bosons Gauge Bosons

photon

gluon

W

Z

The W and Z bosons are mediators for weak interactions whereas the gluon mediates strong interactions and the photon mediates electromagnetic interactions.

H…

Putting the brain on trial: did your brain make you do it? Neuroscience in the courtroom exposed. Plus the dark side of new neurotechnologies and do we have free will or are our actions pre-determined? This special Naked Neuroscience podcast series reports from Washington DC, where the International Neuroethics Society hosted their annual meeting at the AAAS headquarters. Podcast supported by the…

The Discovery of the Higgs Boson

The full playlist of the free MOOC, on the “Discovery” of the Higgs Boson offered by the University of Edinburgh.

Some lectures are better explained than others are, because this course uses a mix of lecturers to cover various elements and some explain things better than others do. However, it is worth noting that overall, pretty…

A step by step guide on how to set up a convenient profile for  gnome-terminal so it is easy to identify what shell you are using. 

Step 1.

Edit $HOME/.bashrc by adding the following lines:

    if [ -n "$UNDER_JHBUILD" ]; then     PS1="[JHBuild@\W] "     fi

If you think you will be working in the directories where your git modules check in and install to it is also worth adding the line cd $HOME/gnome click 'Details' for more instruction on what to do or otherwise skip straight to Step 2.

Here I have assumed that your prefix and checkout are set to $HOME/gnome/install and $HOME/gnome/source, respectively.  You can find out your prefix and checkout root by checking your .jhbuildrc if you have one or otherwise checking defaults.jhbuildrc

    if [ -n "$UNDER_JHBUILD" ]; then        PS1="[JHBuild@\W] "         cd $HOME/gnome     fi

Step 2.

In an open terminal go to  edit > profile preferences

Step 3.

From the profile preferences dialogue go to the title and command tab and type "JHBuild" into the "initial title" field.

Step 4.

From the title and command tab select the 'run custom command instead of my shell' and type "jhbuild shell" (all lower case) into the "custom command"  field:

Screenshot to demonstrate what is needed for Step 3. to Step 4.

Step 5.

In an open terminal go to file > open terminal > jhbuild

Step 5.

Final Check

If that worked, then the fresh profile window should look something like this