Archive for the ‘Signal Processing’ Category

You Can Confirm A Gravity Wave!

Saturday, February 13th, 2016

Unless you have been unconscious since last Wednesday, you have heard about the confirmation of Einstein’s 1916 prediction of gravitational waves.

An very incomplete list of popular reports include:

Einstein, A Hunch And Decades Of Work: How Scientists Found Gravitational Waves (NPR)

Einstein’s gravitational waves ‘seen’ from black holes (BBC)

Gravitational Waves Detected, Confirming Einstein’s Theory (NYT)

Gravitational waves: breakthrough discovery after a century of expectation (Guardian)

For the full monty, see the LIGO Scientific Collaboration itself.

Which brings us to the iPython notebook with the gravitational wave discovery data: Signal Processing with GW150914 Open Data

From the post:

Welcome! This ipython notebook (or associated python script GW150914_tutorial.py ) will go through some typical signal processing tasks on strain time-series data associated with the LIGO GW150914 data release from the LIGO Open Science Center (LOSC):

To begin, download the ipython notebook, readligo.py, and the data files listed below, into a directory / folder, then run it. Or you can run the python script GW150914_tutorial.py. You will need the python packages: numpy, scipy, matplotlib, h5py.

On Windows, or if you prefer, you can use a python development environment such as Anaconda (https://www.continuum.io/why-anaconda) or Enthought Canopy (https://www.enthought.com/products/canopy/).

Questions, comments, suggestions, corrections, etc: email losc@ligo.org

v20160208b

Unlike the toadies at the New England Journal of Medicine, Parasitic Re-use of Data? Institutionalizing Toadyism, Addressing The Concerns Of The Selfish, the scientists who have labored for decades on the gravitational wave question are giving their data away for free!

Not only giving the data away, but striving to help others learn to use it!

Beyond simply “doing the right thing,” and setting an example for other scientists, this is a great opportunity to learn more about signal processing.

Signal processing being an important method of “subject identification” when you stop to think about it in a large number of domains.

Detecting a gravity wave is beyond your personal means but with the data freely available…, further analysis is a matter of interest and perseverance.

Processing Rat Brain Neuronal Signals Using a Hadoop Computing Cluster – Part II

Wednesday, August 1st, 2012

Processing Rat Brain Neuronal Signals Using a Hadoop Computing Cluster – Part II by Jadin C. Jackson, PhD & Bradley S. Rubin, PhD.

From the post:

As mentioned in Part I, although Hadoop and other Big Data technologies are typically applied to I/O intensive workloads, where parallel data channels dramatically increase I/O throughput, there is growing interest in applying these technologies to CPU intensive workloads. In this work, we used Hadoop and Hive to digitally signal process individual neuron voltage signals captured from electrodes embedded in the rat brain. Previously, this processing was performed on a single Matlab workstation, a workload that was both CPU intensive and data intensive, especially for intermediate output data. With Hadoop/Hive, we were not only able to apply parallelism to the various processing steps, but had the additional benefit of having all the data online for additional ad hoc analysis. Here, we describe the technical details of our implementation, including the biological relevance of the neural signals and analysis parameters. In Part III, we will then describe the tradeoffs between the Matlab and Hadoop/Hive approach, performance results, and several issues identified with using Hadoop/Hive in this type of application.

Details of the setup for processing rat brain signals with Hadoop.

Looking back, I did not see any mention of data sets? Perhaps in part III?

Processing Rat Brain Neuronal Signals Using A Hadoop Computing Cluster – Part I

Tuesday, July 31st, 2012

Processing Rat Brain Neuronal Signals Using A Hadoop Computing Cluster – Part I by Jadin C. Jackson, PhD & Bradley S. Rubin, PhD.

From the introduction:

In this three-part series of posts, we will share our experiences tackling a scientific computing challenge that may serve as a useful practical example for those readers considering Hadoop and Hive as an option to meet their growing technical and scientific computing needs. This first part describes some of the background behind our application and the advantages of Hadoop that make it an attractive framework in which to implement our solution. Part II dives into the technical details of the data we aimed to analyze and of our solution. Finally, we wrap up this series in Part III with a description of some of our main results, and most importantly perhaps, a list of things we learned along the way, as well as future possibilities for improvements.

And:

Problem Statement

Prior to starting this work, Jadin had data previously gathered by himself and from neuroscience researchers who are interested in the role of the brain region called the hippocampus. In both rats and humans, this region is responsible for both spatial processing and memory storage and retrieval. For example, as a rat runs a maze, neurons in the hippocampus, each representing a point in space, fire in sequence. When the rat revisits a path, and pauses to make decisions about how to proceed, those same neurons fire in similar sequences as the rat considers the previous consequences of taking one path versus another. In addition to this binary-like firing of neurons, brain waves, produced by ensembles of neurons, are present in different frequency bands. These act somewhat like clock signals, and the phase relationships of these signals correlate to specific brain signal pathways that provide input to this sub-region of the hippocampus.

The goal of the underlying neuroscience research is to correlate the physical state of the rat with specific characteristics of the signals coming from the neural circuitry in the hippocampus. Those signal differences reflect the origin of signals to the hippocampus. Signals that arise within the hippocampus indicate actions based on memory input, such as reencountering previously encountered situations. Signals that arise outside the hippocampus correspond to other cognitive processing. In this work, we digitally signal process the individual neuronal signal output and turn it into spectral information related to the brain region of origin for the signal input.

If this doesn’t sound like a topic map related problem on your first read, what would you call the “…brain region of origin for the signal input[?]”

That is if you wanted to say something about it. Or wanted to associate information, oh, I don’t know, captured from a signal processing application with it?

Hmmm, that’s what I thought too.

Besides, it is a good opportunity for you to exercise your Hadoop skills. Never a bad thing to work on the unfamiliar.