Recent content by daveyrocket

That's interesting stuff, I'll look at it later when I have more time. As I examine this problem in greater detail, I'm finding is that there are multiple local minima which provide pretty good fits, one could probably not argue that P(params) is much different for one choice than the other. So...

Perhaps what he means is that it's frequent enough that when a single such instance is examined, you can't conclude that she murdered her babies based on the statistical improbability of it happening. The first claim was that if it happens at all, it's got to be murder because it's too...

Hmm I see what you mean. That might work. I'll have to think about that. I haven't written code to do the curve fitting yet. Since the model functions are nonlinear, it'll be an iterative method, maybe steepest decent, although I'm not sure I want to be calculating gradients.

A move in Monte Carlo is a decision about how to change your parameters. For example, in the Hirsch-Fye algorithm, you have a set of Ising spins which can take on values of +1 or -1. So the simplest move in HF is easy, just choose a spin at random and flip the sign. Once you've decided on a...

Fractional occupation is often used as a numerical integration technique for metals. If you have a Fermi surface and you're integrating over a discrete grid of points, the abruptness of the change in the occupation results in very slow convergence wrt the grid density. Using fractional...

I have several data points with error bars, and these error bars are different sizes for each of the data points. I'd like to fit a model function to them which has non-linear parameters, and be able to get error bars on the model parameters, ie. if my model is something like f(x) = A +...

Well I'm no expert on x-ray experiments. I know a bit more about x-ray absorption spectroscopy, which is a bit different than emission, which is what you're talking about. But to the best of my knowledge: 1. Yes, you should see broadening due to band effects. X-ray energies are on the order of...

I'm not sure what d is. Is that your diagonal in the cube? You're using the wrong triangle for the Pythagorean theorem. The diagonal of a cube is not the same length as the diagonal of a square.

The two closest atoms in the diamond structure aren't the two on the face of the fcc cell, it's the one in the corner and the one it's nearest inside the cell. See the purple bond in your picture. That distance is 2r.

Yes, it is definitely important to enjoy the process of doing physics, or of whatever you end up doing. If you find doing physics boring, you can't just tolerate it for the amazing results in the end, because most research doesn't produce amazing results. The stuff you read about in the books...

The is the implication when you make a statement like that is that you're dismissive of any problem that might happen in the first world. If you have an actual criticism, then throw that out rather than the lame "first-world problem" line. But next time, try to pay attention to the context of...

I really don't understand why people seem to think this is a legitimate criticism of anything. Is the implication that first-world problems aren't worth discussing or solving? Like the 2008 economic collapse which put millions of people out of work and destroyed the economies of several...

There are other things too, like if you own a home and have to make a mortgage payment. I did my PhD and a postdoc right after my bachelor's and now in my early 30's I'm really really sick of living in one bedroom apartments.

Well, the environment provides us with a lot of useful things, and historically when we've gone and "altered away" this has had some significant, negative, unforeseen consequences for us. There's some arguments and evidence out there that the destruction of wetlands in Louisiana has caused...

Scale is the first difference that comes to mind. I haven't been talking about rights though, so I'm not sure where that is coming from. I didn't say it was required, I said it created burdens. Even if I wanted to live in a NY subway station, I'd still have to come up with the money to get...