PSC Celebrates International Women's Day

On International Women’s Day, we asked team members: who are the women in STEM who inspire you, or inspired your STEM journeys? We got some great insight and are excited to celebrate great women all month!

Staff Spotlight: Michelle Devlin

Michelle is PSC’s Administrative Coordinator. Her specialty is managing and distributing information within PSC. She completes travel requests, expense reports, makes travel arrangements, orders supplies and pays invoices. We appreciate you, Michelle! PSC Superpower: Always the point of contact.

Bridges Retires After 5 Super Years

From the vastness of neutron-star collisions to the raw power of incoming tsunamis to the tiny, life-and-death details of how COVID-19 progresses,  Bridges has seen it all. Now Bridges has taken its final bow, giving way to the larger, more advanced Bridges-2.

AI Uses Language Rules, Simulates Molecular Motion

A team from the University of Maryland used natural language processing AI on  Bridges to recreate known chemistry, showing that AI may be able to reduce molecular dynamics to rules of grammar and syntax.

Custom Conda Environments with OnDemand on Bridges-2

You can use the Python “ipykernel” package to create a definition file for Jupyter Notebook which uses a custom Python installation rather than the default one. After creating that file and launching Jupyter Notebooks via OnDemand, you can use your custom environment.

The steps to do this are:

  1. Install “ipykernel”.
  2. Create the custom Jupyter Notebook kernel.
  3. Start the custom Jupyter Notebook kernel.

Install “ipykernel”

This process can be performed with a custom Conda environment, with the Python installation in the Bridges-2 nodes, or with any other Python installation available; the important thing is to run it from the Python environment that will be used with OnDemand.

The “ipykernel” package must be available in this environment to generate the custom kernel. The “ipykernel” package can be removed after that.

Load and activate the Anaconda3 module

In an interactive session on Bridges-2, load and activate anaconda3.

module load anaconda3
conda activate # source /opt/packages/anaconda3/etc/profile.d/

Add ipykernel to an environment

Create a new environment and install the “ipykernel” package along with any other packages you might need, or install “ipykernel” to any existing Conda environment you have.

To create a new environment which includes ipykernel

Use a command like

conda create --name ENVIRONMENT_NAME ipykernel
conda activate ENVIRONMENT_NAME
To add ipykernel to an existing environment

Use a command like one below, depending on your specific case:

If you are using Conda:

conda install ipykernel

If you are NOT using Conda, but in a Python environment in which you have write permission

python3 -m pip install ipykernel

To use the default Bridges-2 Python installation or modules

python3 -m pip install ipykernel --user

Create the custom Jupyter Notebook kernel

Run “ipykernel” to create the custom Jupyter Notebook kernel, so that the Python installation is mapped using a definition file. This can be done by either running the “ipykernel” module from the environment that is going to be used, or by running the module while specifying the full path to reach that environment location.

Note: The environment must be activated before running ipykernel.

After running this command, a file is created which specifies the location of the Python environment. That file will be created under one of the following locations.


The output of the command shows the location of this file.

(base) [user@r001 custom-kernel]$ conda activate NEW_ENV
(NEW_ENV) [user@r001 custom-kernel]$

(NEW_ENV) [user@r001 custom-kernel]$ python3 -m ipykernel install --user --name NEW_ENV --display-name "PYTHON-ENV-NAME"
Installed kernelspec NEW_ENV in /jet/home/user/.local/share/jupyter/kernels/new_env
(NEW_ENV) [user@r001 custom-kernel]$

Note: The “ipykernel” can be removed from the environment after the custom kernel is created.

Start the custom Jupyter Notebook kernel

Now you are ready to start your custom Jupyter notebook kernel from an interactive session in OnDemand.

Log in to OnDemand
In a browser window, go to and log in with your PSC credentials.
Request an interactive session for your Notebook.

Navigate to Interactive Apps > Jupyter Notebook

OnDemand at Bridges-2. Interactive Apps tab, Jupyter Notebook item

A new screen will open which allows you to specify the paramters for your interactive session (number of hours, nodes, partition, etc.) Set the parameters for your session as needed.

Click the blue Launch button. You may have to wait for resources to be allocated to you. Once your session has started, click the blue Connect to Jupyter button.

At this point, you can start a new notebook or open an existing one.

Start a new notebook

Under the New dropdown in the upper right, choose the name of the new environment that you created.

OnDemand at Bridges-2. Jupyter Notebook is running, and a new Notebook is being started while selecting the custom Python environment just created

Your new Notebook will open.

Note: For installing new packages, you will have to do it from the terminal in the interactive session and NOT from the Jupyter notebook itself as it will try to use the base different Conda binaries and not the ones you set in the new custom environment kernel.

Use an existing Notebook

If you already have a notebook, find it in the file list and click on it to open it.

Change the Python environment to use by navigating to Kernel > Change kernel. Choose the new Python environment to use.


Note: For installing new packages, you will have to do it from the terminal in the interactive session and NOT from the Jupyter notebook itself as it will try to use the base different Conda binaries and not the ones you set in the new custom environment kernel.

Additional content: using Python from Singularity containers

Similar to the process described on, a Python installation inside a Singularity container can be used from Jupyter Notebook as well, although the process is somewhat manual for now.

Create a new directory under $HOME/.local/share/jupyter/kernels/ and add a kernel.json file there with the commands needed for Singularity to start the python binary it has inside.


mkdir -p $HOME/.local/share/jupyter/kernels/tensorflow_latest/
vim $HOME/.local/share/jupyter/kernels/tensorflow_latest/kernel.json
    "argv": [
    "display_name": "tensorflow_latest",
    "language": "python"

Then start Jupyter Notebook and select the newly created kernel. The libraries inside the container should be there.

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