daily discovery

Laser printer cartridges are not carcinogenic

2008-02-25T14:38:00.003+11:00

From this discussion on laser printer cartridges back in 1991:

Laser printer toner's major constituent is carbon black, which is "a finely divided form of carbon made from the incomplete combustion of hydrocarbons." ... The studies in the information I have found that carbon black is not carcinogenic. The information I am referring to is the documentation for TLV's put out by the American Conference of Governmental Industrial Hygienists, 5th edition.

So no need to worry!

Cheers,
Steve

/etc/ftpusers, not what you think

2008-02-15T14:03:00.003+11:00

The filename ftpusers seems to imply the users present in the file would be allowed to login via ftp, but this isn't so! It is apparently a left over from the wu-ftpd days, and it is a blacklist of users who are not allowed to login via ftp!

Cheers,
Steve

About Tigers and Polar Bears

2008-02-02T18:13:00.000+11:00

I know it is slashdot, but I couldn't find other sources, so take this with a grain of salt:

Tigers have practically no natural instincts when it comes to being predators. Tigers in the wild have to be trained by their mothers how to do things like hunt, climb trees, eat properly, etc. These are things that a human cannot teach. Therefore, any tiger born in captivity cannot be released into the wild and survive. It simply does not have the skills necessary.

22262422

Not to be a pedant but Polar Bears in their natural habitat will actively hunt humans.

- 22263306 If anyone knows for sure, let me know :D Cheers, Steve

SHA Digests under Leopard

2007-11-23T00:06:00.000+11:00

A Steve Special this one. Tiger came with sha* digests binaries, but not Leopard. So here is how you can get them back. Insert into your .bashrc:


alias 'sha'='openssl dgst -sha'
alias 'sha1'='openssl dgst -sha1'

# the following lines only applies if you have openssl installed via darwin ports
alias 'sha2'='openssl dgst -sha256'
alias 'sha5'='openssl dgst -sha512'

Usage is simple, for example: sha1 $file Cheers, Steve

The Sagnac effect

2007-11-19T15:24:00.000+11:00

The Sagnac effect is the relative phase shift between two beams of light that have traveled an identical path in opposite direction in a rotating frame. Modern fiber-optic gyroscopes (Sagnac interferometers) used for navigation are based on this effect. They allow highly accurate measurements of rotation rates down to about per hour.

Cheers, Steve

Using spaces and backslashes in /etc/fstab

2007-06-15T23:45:00.000+10:00

Ever wondered how you use spaces and backslashes (exotic mount points or smb shares)? Well wonder no more!

Using '\040' replace blank space character, and '\134' replaces backslash character.

Cheers, Steve

macam

2007-05-09T23:37:00.000+10:00

macam allows most generic usb webcam to work under OS X effortlessly. Cheers, Steve

Diameter at Breast Height

2007-03-28T22:09:00.000+10:00

A common measure of the size of a tree is the "diameter at breast height" DBH. "Breast height" is defined as 4 ½ feet above the uphill side of the tree. Since a tree trunk is not a perfect circle, "diameter" is defined as the circumference divided by pi.

Cheers, Steve

Planck Temperature

2007-02-23T15:16:00.000+11:00

Planck temperature is the highest possible temperature in quantum mechanics. It is 1.41679(11)E32 Kelvins. Cheers, Steve

The Chinese Zero

2006-12-08T15:24:00.000+11:00

Zero was introduced into Chinese mathematics through diffusion from the Hindus:

Evidently, as pointed out by Mikami [13] and others, the Chinese borrowed the zero concept from the Hindus, with whom they established contact at least as early as the first century, A.D. Here we have an example of its introduction by diffusion, but without such contacts, the zero would probably have evolved in Chinese mathematics, especially since calculators of the rod type were employed.

Cheers, Steve

Gravity toggle

2006-11-12T22:37:00.001+11:00

No its not a device from the future (yet) but rather one of these:
Clever! Cheers, Steve

Real pearls

2006-10-26T14:30:00.000+10:00

Dissolve in vinegar. Cheers, Steve

Extended Euclidean algorithm

2006-10-24T12:38:00.000+10:00

Can be used to determine if a number g belongs in a multiplicative group Zp* since it finds the integers x,y such that:

gx+py = gcd(g,p)

where x is the multiplicative inverse of a mod b. If 1 < x < p-1 then the number g belongs Zp*. Cheers, Steve

Maggots

2006-10-10T15:34:00.000+10:00

Live maggots are sometimes applied to chronic wounds because they eat dead tissue, but leave healthy tissue alone

[disinfected maggots in open wound]

Cheers, Steve

Cure-all for intractable hiccups

2006-10-06T19:34:00.000+10:00

"An orgasm results in incredible stimulation of the vagus nerve. From now on, I will be recommending sex – culminating with orgasm – as the cure-all for intractable hiccups." - Francis Fesmire

Cheers, Steve

G forces during an Apollo launch abortion

2006-10-04T14:40:00.000+10:00

Up to 16.2g of g-force maybe experienced by astronauts during an Apollo launch abortion. Cheers, Steve

Telstra Concord Telephone Exchange

2006-09-15T13:34:00.000+10:00

Is located at 35 Yaralla St, Concord 2137. Cheers, Steve

mii-tool

2006-09-13T17:13:00.000+10:00

mii-tool can be used to check the speed at which your ethernet card is operating at under Linux. For example:

eth0: negotiated 100baseTx-FD flow-control, link ok product info: Intel 82555 rev 0 basic mode: autonegotiation enabled basic status: autonegotiation complete, link ok capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control

Above tell us the network link over at interface eth0 is working at 100baseT speeds and FD means full-duplex. Cheers, Steve

HDD Recovery tricks

2006-08-19T16:40:00.000+10:00

Due to the way IDE drivers deal with bad sectors and stuff, the following tricks might be useful raising a dead or bad drive from the dead:

dd if=/dev/hda of=/dev/hda bs=512

Here is another one:

cat /dev/urandom > /dev/hdb and then cat /dev/zero > /dev/hdb

Doing that a few times should get the drive to re-map any bad sectors. Cheers, Steve

Generating padded sequences with jot

2006-08-11T18:50:00.000+10:00

Here is an example on how to generate 3 digit 0-padded numbers from 1 to 250 using jot:

jot -w "%.3d" 250 1 250 1

Cheers, Steve

KML

2006-06-20T17:14:00.000+10:00

KML stands for Keyhole Markup Language and is used to describe entities with in Google Earth. Cheers, Steve

23

2006-04-05T00:54:00.000+10:00

23 is the largest integer that is not the sum of distinct powers.

machihembras

2006-03-24T01:13:00.000+11:00

Machihembras means "first woman, then man". Warning: site contains some nudity. Cheers, Steve

Phonon

2006-03-21T22:12:00.000+11:00

Phonon is a quantised mode of vibration in a rigid crystal lattice that sometimes serves to conserve the crystal momentum during band-gap transitions of electrons. Cheers, Steve

Stopping iPhotos from automatically opening on photo media insertion

2006-03-20T23:07:00.000+11:00

Run /Applications/Image Capture.app and in preferences, set "When a camera is connected, open" to "none". Cheers, Steve