I started working as a research software engineer for the Princeton Neuroscience Institute (PNI) in May 2017. At the end of my first week I received an email from Professor Mala Murthy and post-doc David Deutsch of the MurthyLab, asking if I would be interested in working on a project involving a “virtual reality environment for neural recording experiments”. The kid in me got very excited at the prospect of making video games. At the time I did not know the project was to develop a virtual reality simulation for flies!

The FlyVR setup. Projection arena for visual stimuli not shown as it surrounds parts of the setup and occludes components. Projector for visual stimuli is directed at a curved mirror to project onto half dome surrounding fly.

Virtual reality experiments have a long history in neuroscience . They allow researchers to restrict the movement of animal subjects so that they can use advanced microscopy to image their brains in “naturalistic” environments. In the Murthy lab’s VR setup, the fly is fixed to the objective of a two photon microscope and suspended above a small sphere floating on a column of air. This small sphere is used as a sort of omni-directional treadmill. While the fly cannot actually move, it can move its legs, which in turn move the freely rotating sphere. The movement of the sphere is tracked with computer vision algorithms and thus a fictive path for the fly in a virtual world can be reconstructed. This setup allows a “moving” fly’s brain to be imaged with techniques that require it to be stationary. The two photon imaging system then provides a very flexible and powerful tool for studying changes in the fly’s brain activity over time of the experiment. Different spatial and temporal resolutions are available depending on the needs of the experimenter. 

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Monitoring slurm efficiency with reportseff


As I started using Snakemake, I had hundreds of jobs that I wanted to get performance information about. seff gives the efficiency information I wanted, but for only a single job at a time. sacct handles multiple jobs, but couldn’t give the efficiency. With the current python implementation of reportseff, all job information is obtained from a single sacct call and with click the output is colored to quickly see how things are running.

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Boost Histogram 0.6

boost-histogram logo

The foundational histogramming package for Python, boost-histogram, was just updated to version 0.6! This is a major update to the new Boost.Histogram bindings. Version 0.6.1 is based on the recently released Boost C++ Libraries version 1.72 Histogram package.

This Python library is part of a larger picture in the Scikit-HEP ecosystem of tools for Particle Physics and is funded by DIANA/HEP and IRIS-HEP. It is the core library for making and manipulating histograms. Other packages are under development to provide a complete set of tools to work with and visualize histograms. The Aghast package is designed to convert between popular histogram formats, and the Hist package will be designed to make common analysis tasks simple, like plotting via tools such as the mplhep package. Hist and Aghast will be initially driven by HEP (High Energy Physics and Particle Physics) needs, but outside issues and contributions are welcome and encouraged.

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Configuration settings in the ASPIRE package

As with any substantial application package, the ASPIRE project needed a convenient way to specify configuration settings pertaining to different parts of the computational pipeline.

What follows below are some outlines from our attempts to tackle this configuration issue. Where a supplementary (and hopefully useful) nugget is provided, or a caveat discussed, I shall append a linked numeral, like so: (n)

A brief background of ASPIRE

ASPIRE is a Python (3.6) package under development, which ingests Micrographs, the output of Cryo-Electron Microscopy (images that closely resemble television static), and comes up with a 3D reconstruction of the molecule. Read the excellent writeup on the ASPIRE page for a more comprehensive review of the package.

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Developing a GPU Version of APPLE-Picker in a Five-day Hackathon Event

Background on APPLE-Picker

APPLE-Picker is a submodule of ASPIRE Python package in development for reconstructing a 3D CryoEM map of biomolecule from corresponding 2D particle images, developed by the researchers in Professor Amit Singer’s group. It is an automatic tool to select millions of particles from thousands of micrographs, a critical step in the pipeline of CryoEM image reconstruction. It used to be performed manually but can be very tedious and difficult especially for small particles with low contrast (low signal-noise ratio). The CPU version takes ~80 seconds on average to finish processing one micrograph. To achieve the goal of finishing thousands of micrographs in a few minutes, we need an alternative method, such as GPU accelerating.

2019 Princeton GPU Hackathon

Princeton university held its first GPU hackathon on campus this summer from June 24 to 28, organized and hosted by the Princeton Institute for Computational Science and Engineering (PICSciE), and co-sponsored by NVIDIA and the Oak Ridge Leadership Computing Facility (OLCF). The main goal of this Hackathon was to port research codes to GPUs or optimize them with the help of experts from industry, academia and national labs, as emphasized by Ian Cosden, one of lead organizers and manager of Princeton’s Research Software Engineering Group. This blog reports our attempts and the story behind accelerating APPLE-Picker using GPU and parallel computing in Python.

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Development of Python ASPIRE Package

Background on ASPIRE (Algorithms for Single Particle Reconstruction)

Significant progress on computational algorithms and software is one of the major reasons leading the revolution of resolution in three dimensional structure determination of biomolecules using CryoEM, a technique projecting rapidly frozen and randomly orientated 3D particles into 2D noisy images on micrographs and reconstructing 3D density maps in atomistic resolution through computer software. Due to many crucial roles of 3D biomolecules such as protein enzymes for further study in structural and chemical biology, biophysics, biomedical and other related fields, the 2017 Nobel prize in chemistry was awarded to three scholars for significantly advancing the CryoEM technique as explained in this Youtube video.

During the past 10 years, Professor Amit Singer’s group has proposed many new ideas in various numerical algorithms and developed the ASPIRE Matlab package to tackle many problems involved in reconstructing a 3D CryoEM map of biomolecule from corresponding 2D particle images, including CTF estimation, denoising, particle picking, 2D and 3D classification, and ab initio 3D reconstruction.

Feature Summary of ASPIRE
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Hello World from the Princeton RSE Group!

Welcome to the first Princeton RSE group blog entry!  Before we get into the good stuff, here’s a bit of background

About Us

A relatively new addition, the Princeton RSE group formed in late 2016 within the Princeton Research Computing Department.  We develop software long term with traditional research groups to enable and advance research. We strive to develop high quality software both in terms of performance, and sustainability/maintainability.  We work alongside research groups from multiple disciplines.  You can read more about our group on our webpage and the individual members of our group here.

What you can expect out of this blog

We’ll be sharing software projects we’ve worked on including major releases, scripts and solutions we’ve generated, and little interesting discoveries that have come up along the way.  We’re looking to share some of the best practices we’ve settled on, point out some lessons learned, and try to foster discussions within the broader RSE and research software community.