Category: Oddities

Who’d’a thunk it?

Medical Image CD: FAIL

I asked for the images from recent X-ray and MRI sessions, whereupon a CD arrived in the mail. Popping it into my desktop Linux box produced this directory listing:

ll /run/media/ed/Feb\ 21\ 2025/
total 146M
dr-xr-xr-x  2 ed   ed    136 Feb 21 13:14 ./
drwxr-x---+ 3 root root   60 Mar  2 13:40 ../
-r--r--r--  1 ed   ed   146M Feb 21 13:14 -NISLEY-DMBG8yMQcf8qXcVj.iso

It seems whoever / whatever produced the CD copied the ISO image to the CD, rather than burning the ISO directly to the CD. As a result, the CD has one file.

Raise your hand if you’ve never done that.

Well, I was going to save the CD as an ISO file anyway, so I just copied it to the file server.

Attempting to mount it produces an odd result:

sudo mount -o loop "-NISLEY-DMBG8yMQcf8qXcVj.iso" /mnt/loop/
[sudo] password for ed: <make up your own>
mount: failed to set target namespace to ISLEY-DMBG8yMQcf8qXcVj.iso: No such file or directory

Oh, right, starting a filename with a leading dash is never a Good Idea™.

Rename it:

mv -NISLEY-DMBG8yMQcf8qXcVj.iso NISLEY-DMBG8yMQcf8qXcVj.iso
mv: invalid option -- 'N'
Try 'mv --help' for more information.

Which is why leading dashes are a Terrible Idea™.

Force the rename to happen:

mv ./-NISLEY-DMBG8yMQcf8qXcVj.iso NISLEY-DMBG8yMQcf8qXcVj.iso

The same syntax works in the mount command, but it’s easier to solve the problem once and be done with it.

Now mount the file:

sudo mount NISLEY-DMBG8yMQcf8qXcVj.iso /mnt/loop
mount: /mnt/loop: WARNING: source write-protected, mounted read-only.

That’s entirely expected, because the whole filesystem is intended for a non-writeable CD.

What’s inside?

ll /mnt/loop/
ls: cannot open directory '/mnt/loop/': Permission denied

Why would that be?

ll /mnt
total 58K
drwxr-xr-x 15 root root 4.0K May 21  2023 ./
drwxr-xr-x 17 root root 4.0K Mar  2 13:43 ../
… omitted …
drwxrwx---  4  496  495 2.0K Feb 21 13:13 loop/
… omitted …

Maybe 496 and 495 are the UID and GID of whatever created the CD?

Force it to my UID:

sudo umount /mnt/loop
[ed@shiitake tmp]$ sudo mount -o uid=ed NISLEY-DMBG8yMQcf8qXcVj.iso /mnt/loop
mount: /mnt/loop: WARNING: source write-protected, mounted read-only.
[ed@shiitake tmp]$ ll /mnt/loop
total 16K
drwxrwx---  4 ed    495 2.0K Feb 21 13:13 ./
drwxr-xr-x 15 root root 4.0K May 21  2023 ../
drwxrwx---  4 ed    495 2.0K Feb 21 13:12 data/
drwxr-xr-x  5 ed    495 2.0K Feb 21 13:13 DICOM/
-rw-rw----  1 ed    495 1.7K Feb 21 13:12 README.txt
-rw-rw----  1 ed    495 3.2K Feb 21 13:12 view-studies.html

Now that’s more like it.

Finally, I can fire up Weasis to look at pretty DICOM images:

Spine - lateral T2 TSE SAG - 2025-02 - tweaked — Spine – lateral T2 TSE SAG – 2025-02 – tweaked

Apparently things looks suspicious around L4.

2025-03-05

Why I No Longer Trust Google Weather

You can’t make this stuff up:

Google Weather App – precipitation puzzle

We didn’t get half a foot of any precipitation that day.

That is apparently the “Pixel At a Glance” app using info scraped from weather-dot-com. The other Google Weather app, the one that may or may not still have the Weather Frog, scrapes info from noaa-dot-gov and seems somewhat less uncoordinated.

The two apps generally disagree on what kind and how much precipitation will occur, sometimes absurdly, and rarely agree with the official National Weather Service forecast.

Sometimes the forecasts have not converged by the time the weather arrives outside the window.

2025-02-20
Laser-Engraved CD Stress Cracking

Given the cracking caused by vector patterns on CDs and DVDs, seeing stress cracks open up on large-area engravings came as no surprise:

Laser engraved CD cracking – D

They start smaller in the more closely engraved areas:

Laser engraved CD cracking – A

But eventually spread over the entire surface:

Laser engraved CD cracking – C

They’re not always straight:

Laser engraved CD cracking – B

And aren’t aligned with the engraving path:

Laser engraved CD cracking – B detail

My threat model says those discs are definitely unreadable …

2025-02-07
Hotel California: Vole Edition

Although we had considerable success trapping voles during the last half of the 2024 gardening season, Mary found a description of what might be a better technique: a box with small entrance holes taking advantage of rodent thigmotaxis: their tendency to follow walls. The writeup shows nicely made wood boxes, but I no longer have machinery capable of cutting arbitrarily large wood slabs into pieces.

I do, however, have a vast pile of cardboard boxes:

Vole Box – large

That’s a rat-size trap.

A smaller box has room for two mouse-size traps (one hidden on the left):

Vole Box – small

The general idea: plunk the box in a garden plot, arm the trap(s), close the lid, and eventually a vole will venture inside, whereupon wall-following leads to disaster. Apparently bait is optional, as wall-following inevitably takes them over the trap pedal. I won’t begrudge them a walnut or two, should bait become necessary.

Cardboard is obviously the wrong material for a box in an outdoor garden, but I figure they’ll survive long enough to show feasibility and I can deploy a lot of small boxes before having to conjure something more durable.

Yes, those are laser-cut rounded-rectangle holes: 30 mm and 40 mm, assuming voles care about such things.

Edit: More on voles.

2025-01-28
Walking to Work: Goose Gaggle

As the poster says, “Until you spread your wings, you’ll have no idea how far you can walk”:

Goose Tracks – Vassar Sunset Lake – A

My feet get chilly just looking:

Goose Tracks – Vassar Sunset Lake – B

We think the flock has a Rules Compliance Officer who gave one miscreant goose an all-around inspection:

Goose Tracks – circling

Just another day at the office …

The WordPress AI generated an excerpt for this post:

The poster emphasizes potential discovery through exploration, while the goose flock exhibits curiosity, hinting at humorous governance among them at Vassar Sunset Lake.

I had no idea “governance” was a goose thing.

2025-01-27
Whole House Filter Disassembly

The sediment and carbon filter cartridges in our house call for annual replacement and I wondered what was inside the big cartridge.

Much to my surprise, the white plastic cap unscrews easily after grabbing the filter in the bench vise and applying a strap wrench:

Whole house carbon filter – endcap

Water enters around the perimeter of the cap, flows through the media in the cylindrical cartridge, and emerges near the center at the other end. The filter is upside-down in the vise: the cap is on the bottom of the cartridge when it’s installed in the filter housing.

The brown stuff looks a lot like sand, but is probably KDF-85 media acting as a prefilter for the carbon:

Whole house carbon filter – prefilter

The white fiber pad separates the KDF-85 from the carbon granules filling the rest of the filter:

Whole house carbon filter – carbon

Atypically, I couldn’t think of anything to do with the empty cartridge, so I screwed the lid back on and lowered the whole mess into the trash can.

Now I know what’s inside!

2025-01-20
Sinking Rocks

Trigger warning: trypophobia fuel.

Spotted on the walking path near the Vassar College golf course:

Sinking Stones – A

They’re everywhere:

Sinking Stones – B

I think the path surface rises as it freezes, then the stones sink into the loosened soil as they warm up. Other parts of the path, generally having more loam / mulch / organic material than mud & pebbles, have an obviously raised / porous / crunchy texture on bitterly cold (by my standards) days.

Surely, someone can pull a PhD thesis from similar observations …

2025-01-17