Recent content by Mark Harder

As a biochemist, I deal with chirality of molecules all the time. If you have a tetrahedral molecule, for example a carbon atom, and all 4 vertices are labeled differently, as in different atoms on each one, then that molecule has a mirror-symmetric one that cannot be superimposed on the...

As I understand topology, any two objects that can be transformed to each other by a continuous function are 'identical' in the sense that their images can be superimposed on each other. If you can write a function that maps one of your tori one-to-one onto another one, then the two are...

One of the roots of ##x^2 -x -1## is ## \frac {1 + \sqrt 5} 2 ## and that = ## \Phi ## .

Lucky, By placing opposite charges near each other you have created an electric dipole. It's field will look similar to that of a magnetic dipole. It will extend throughout space, but its strength will fall off as a higher power with distance than 1/r^2. 1/r^6? I forget what power exactly...

Dammit, I posted a long answer, but PF seems to have deleted it. The short answer is that all of Is flows through the left transistor because you are trying to keep its base at 2V when it tries to stay at 0.7 V above common (what you mean by ground in your circuit). A transistor is a...

Proof by contradiction is overly complicated and you don't need to make any assumptions about a, n and m or break the proof into separate cases. The disproof derives from the facts that a is a natural number and so must be positive, while its factors n and m are drawn from the integers, which...

There are several things missing from your description of the experiment. Am I right in saying that the (ams) thing is a capacitance meter? What is the sensitivity of this device? Your theoretical calculation of the expected capacitance is 0.141 pico farads. That's an extremely small...

I have no issue with your statement as far as it goes; but we must remember that mutations often result in a trade-off. Population A may be resistant to an antibiotic, for instance; but that mutation might also slow the growth and reproduction of A or cause it to use up more energy in order to...

I won't argue with the "very expensive" part. However, the rest of this analysis is self-contradictory, IMO. Mono-targeting drugs are exactly those that produce fewer side effects, all other things being equal. It's the affinities of multiple targets for a pharmaceutical that are likely to...

This reference is from an advocacy organization promoting certain ideas about herbal cancer treatments, not a peer-reviewed report of research into the subject. I gave up reading when I realized that it is a compendium of opinions, not observations.

It's true that there are a lot of repeating sequences, sometimes known - erroneously or not - as 'junk' DNA and presumably mutations in such sequences would be silent. Assuming, that is, the mutated sequence truly has no sequence-sensitive function. Last I heard, this question has not been...

Yep, the snakes are venomous, but those said-to-be-delicious venom glands, they're poisonous.

WTH? All reptiles are protected in Australia? All reptiles in Australia are deadly venomous, mate. Including the tiger snake, BTW. As are all spiders, and those platypuses with venomous spines on their rear legs. Or else they're going to eat you and tuck you under a log underwater, like the...

Your description of the cultural factors at work at Fukushima reminds me of the recent docudrama, "Chernobyl". According to my interpretation, the Soviet system was responsible for the resistance to accepting the truth about the accident, right down to fundamentals like, Did the reactor...

Do you hear the noise when you use a battery-powered device? All the devices you mentioned are powered by line voltage, I think.