Envelope Extraction in Origin

I'm doing "envelope extraction" analysis on my dHvA data. It took me some time to figure out which boxes to check or uncheck on the Origin FFT tool, so I thought I would just document that here, partially so that I remember how to do it myself.

While usually I would apply a window (e.g. "Hamming window") while doing FFT, here it's better to not use a window i.e. use the "Rectangular" window.

Forward FFT
Use "Rectangular Window"
Uncheck "Normalize Amplitude"
Check "Shift Results"

Apply filter

Backward FFT
Select real and imaginary columns
Use "Rectangular Window"
Uncheck "Normalize Amplitude"
Uncheck "Shift Results"

Plot 2*r
Results may be offset in x-direction.

Converting PDF images to EPS

I've had to convert PDF images to EPS quite often over the past few days, and I've developed a foolproof if intricate process to do this conversion. It is especially good for if you only want to convert a small section of a document (i.e. a figure), because if you want to convert the entire document, Ghostview/Ghostscript can do it for you in one step.

Here is my process:
1. Open document in Adobe Reader. Use the Snapshot Tool to select desired area.
2. Open Paint. Paste from clipboard. Save as jpg.
3. Use jpeg2ps to convert to EPS.
4. If necessary, use Ghostview/Ghostscript to resize bounding box. (Select "PS to EPS" under File menu)

If your jpg image is too large, part of it might get cut off in the jpeg2ps conversion. If this happens, resize your jpg image so that it's smaller.

If you know of an easier way to do this, I'd be interested to hear about it. Also please share other document/latex tips you might have.

Organizing PDFs

I'm trying out Zotero as a tool for organizing pdfs of journal articles. My journal articles are always hidden away in multiple folders on my computer and it's hard to find them when I need them. Zotero lets me access them from a central location, and I can tag and search them. If you are viewing certain websites, like Socrates or Physical Review, Zotero will import title/author information for you. It will also export Bibtex.

If you are using a Mac (I don't think any of us are), Papers is the new, awesome scientific paper organizer for Macs. I was searching for a PC version, and that's how I came across Zotero.

PPMS cryopump regeneration

We have been having a lot of trouble with the PPMS cryopump. The manual claims we should only need to regenerate the pump once every 500 uses, but we are needing to regenerate every ~30 uses. Ernest at QD says that, every time we regenerate in dewar, we should run the regeneration command 5 or 6 times, and every time we regenerate out of dewar, we should run it 4 times, then do an in dewar regneration after finishing the out of dewar regeneration. I've modified the regeneration sequences accordingly, and we should all remember to do an in dewar regeneration after finishing an out of dewar regeneration.

Digitizer

This is something I learned from Suchitra: You can use a digitizer such as Engauge Digitizer to read data points off of published graphs.

Corporate Express orders

During our last office supply order, I discovered a few things I thought I'd share

• We have a new catalog on the 4th floor. The old catalog has outdated page numbers.
• We are only allowed to order the following recycled printer paper: EXP8511RCY
• You should not use the old online form, but download a new version of the form from http://www-ssrl.slac.stanford.edu/staffresources/corpexform_nt.pdf, fill it out, and email it to Stephanie Carlson.
  

Heat resistant gloves

Covex gloves, that's what they are... Check out the amazing gloved-hand amidst leaping flames animation on the website http://www.polygenex.com/ :) The orange gloves used for the glass torch, that is - I couldn't find what kind they were all this while, and just managed to locate them.