Recent content by Andrew Mason

As someone with a long held interest in, but no academic background in, molecular biology, I find this is helpful. I became interested in the idea of using polymerase inhibitors to prevent the SARS-CoV-2 virus from replicating and started this thread in June of 2020 on Remdesivir as well as a...

There is a difference, not necessarily a total contradiction. Based on genetic analysis of European skeletons older than 5000 years, inhabitants of Europe before about 3000 BC had mixed genes from hunter-gatherers and Anatolian farmers. Both authors agree on that. Hunter-gatherers arrived in...

It was in 1933, long after Haber's 1918 Nobel prize for making nitrogen fertilizer. The reason, however, is not entirely clear. Rutherford maintained a life-long friendship with Otto Hahn, with whom he worked closely in his Montreal lab. Hahn had worked with Fritz Haber in Germany during WWI...

Yes. But it is not flying level at the bottom portion of the flight path, which is a quarter circle with radius 300m. AM

The question is a bit of a trick question. It says the maximum upward acceleration is 6g. The correct answer is given by ##\vec{a}=-\frac{v^2}{r}\hat{r}=-6\vec{g} ## where the positive direction of ##\vec{a}## is up and that of ##\vec{g}## is down. This results in ##v=132.8 m/s## (assuming...

Interesting point. The only opening for sound is the mouth of the pipe and for sound energy to exit there is an acoustic coupling between the standing wave in the pipe and the travelling wave in the external air. As you point out there is a difference between the ambient air pressure outside and...

Yes, but the stopped wooden organ pipe does not produce a square wave. I am not suggesting that the physics of musical instruments is simple. But according to all the literature I have found, the fundamental and harmonics of an organ pipe are determined by the length of the pipe and whether...

Right. That is how the vibrations originate. So I am confused by your previous reference to "Even harmonics are generated by asymmetrical clipping of the pressure amplitude, like a rectified sinewave. Odd harmonics are generated by symmetrical clipping about zero, like a sinewave with flat...

?? In an organ pipe, the harmonics do not result from clipping sound wave amplitudes. The fundamental and harmonics are generated by resonance within the pipe, which allows standing waves only in discrete multiples of half wave-lengths (open pipe) or discrete odd multiples of quarter...

The terms are interchangeable - at least for our purposes. This is a fairly short pipe so there may be some end effects, lip anomalies, or pipe shape effects (e.g. different path lengths permitted within a square shaped pipe) that could be causing this. These would be reduced with a longer...

A closed pipe with a fundamental frequency of 667 Hz should have overtones of 2001, 3335, 4669 Hz etc corresponding to odd multiples of the fundamental. The open pipe at fundamental 667 Hz should have overtones of 1334, 2001, 2668, 3335, 4002, 4669 Hz. In a wooden pipe, the vibrations in the...

Perhaps the US will reconsider its decision to cut $500 million in funding for mRNA vaccine development: https://www.nature.com/articles/s41587-025-02826-2 AM

Seems that you may have a leaky pipe stopper. If the stopper is not tight to the wood you will get even and odd harmonics because the pipe is acting as both a closed and open pipe. AM

$$\Delta S=\int dS=\int dQ/T$$ is the definition of change in entropy, where dQ is the infinitesimal heat flow over a reversible path. Of course, in realty there is no such thing as a reversible path. A quasi-static path - one in which the thermodynamic changes occur with the system very close...

All good points. But I might take a bit of an issue with the suggestion that the statistical methods are just an approximation. Since thermodynamics was developed before atomic theory and was considered to be a separate field of physical science, the OP is correct in their observation that...