Extended Depth of Field for High-Resolution Scanning Transmission Electron

Extended Depth of Field for High-Resolution Scanning Transmission Electron Microscopy

Robert Hovden,Huolin L. Xin and David A. Muller

Microscopy and Microanalysis, FirstView Articles



http://journals.cambridge.org/action/displayAbstract?aid=7930966

The Daily Cross Hatch

The Daily Cross Hatch, a web blog dedicated to alternative comics, has posted a web comic which I jointly created with Rob Barton and Phil Ashworth.

Article at The Daily Crosshatch

Phil Ashworth's Blooooooooggg

Rotating a Figure or Plot in Matlab

So, if you would like to rotate / invert a figure or plot in Matlab by 90 degrees or by any other specified amount, it is very easy. Simply use:

>> view(90,90)

...and you can go from this:


...to this:


Normally I would not post such a simple tutorial on my blog, however I wasted over a half an hour trying to find out this simple solution. After sifting through a multitude of poor documentation, blog posts, and forum threads, I ended up figuring it out on my own. I would like to say that there are many other ways to achieve this, and I was aware of most of them. I just wanted to know the easiest way and now hopefully the internet finds this useful as well.

The 17x17 Four Color Challenge

Professor Gasarch at the University of Maryland is challenging people to see if a solution exists to a Four Color problem. In his proposed problem, each site of a 17 by 17 grid is occupied by one of four colors. The challenge is to place a color on each site such that all the corners of any rectangle formed from the sites are not the same color. (See Details). He is offering a prize of $289 ($17x17) for a solution (if one even exists). What intrigues me is his lack of prize money for a proof that a solution exists. He want's something that would 'stand up in court'. Which makes me inclined to think he plans to use this for a patentable encryption algorithm. But I'm speculating.

I quickly coded up the problem to get an idea of the solution space and the difficulty of the problem. First off, brute force is out of the question. 4^289 is an incredibly large number and finding all solutions would take longer than the earths lifetime. There may be some branch cut methods to reduce the complexity, but I'm guessing it is still too large.

As a first step, I did a random search of 10,000 configurations and plotted a histogram of the number of solutions with a given number of conflicts. A conflict being the number of rectangles that have four corners of the same color. The plot is depicted below. In summary, we see that the probability of getting a solution with zero rectangles with same colored corners is nearly zero. So, solving this problem is certainly a difficult challenge. Especially with the uncertainty of the existence of a solution.

An Inifinite Number of Primes

In 300 AD Euclid proved that there is an infinite number of primes. A prime number being an integer that is not divisible by any other numbers. The list of prime numbers starts like this: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31 ...

A guy 1700 hundred years ago could prove that this list goes on forever. A colleague, Adam Straub, challenged me to re-derive this without any resources. Adam argued: a person in the 21st century should be able to recreate this simple proof. I was able, but it took some time while driving. I challenge any readers to prove that there is an infinite number of primes before reading the solution. It is a fun challenge that requires middle school level math.

Euclid's Proof:

If we have a list of consecutive primes, starting with 2, 3, 5, .... and so on. We can always prove there is one more prime by multiplying them all together and adding one. We know this knew number is not divisible by any of the primes in our original list. So, either the new number is prime, or it is divisible by a new prime not in our original list.

Example: 2 * 3 * 5 + 1 = 31

So, if we know there is always one more prime in a consecutive list of primes there is always more primes, on to infinity.

I tried to explain this proof as simply as possible, but you can look up Euclid's proof on many other sites or even his original book, Elements (Book IX, Proposition 20) published circa 300 AD.

Living Music – A Live Experience

I have an idea for a creative new form of poetic expression - a kind of real life, walking music video montage. It is nearly impossible to recreate the three dimensional sights, sounds, smells, and touches of the world around us. Even with sight arguably being the most sensational of these physical interactions, a movie falls short. It’s being able to look all directions, focus in on a subject, or squint into the sun.

I’d like to accompany this experience with music. It would be kind of like a walking tour but with music. A real living music video, where the person walks along an author’s predefined path listening to predefined music. The goal of the author would be to recreate the feelings he experienced or wants to experience during his walk.

We all have those moments. Our ears silenced to the outside world by the music playing into our heads. Observing the outside world can almost seem surreal as the music inspires self reflecting thought. This is especially true when the music matches our mood and surroundings. Although it’s hard to predict the mental state of the listener, the goal of the author should be to coerce the listener into a particular mood using sight and sound. Of course, this sounds precisely like a movie or music video, but I think by using the real world it can be much more.

In the end, like most of my ideas, I would like to see others pursue this thought more so than myself. Though I will try. The idea will go in the large scrambled queue that resides in my brain, notebook, and this blog.

Visiting Carl Sagan

Sagan was one of many influential people who called Ithaca home. Reminders of his presence permeates Ithaca and Cornell's campus, which include his house on the Fall Creek Gorge and his final resting place at the Lakeview Cemetery. I recently paid tribute with two friends.

Locating Carl Sagan's grave is not too difficult, but it did take us half an hour. He is buried in Ithaca, New York at the Lakeview Cemetary. The cemetary entrance is gated at the top of a hill overlooking downtown Ithaca. Only a couple hundred feet after the gate, his gravestone is just off the road to the right. We found a multitude of placed stones which had been left by previous visitors. We arranged the colored stones in a line representing the planetary system ranging from the sun to pluto as shown below. I know, Pluto is debatibly a planet, but in Sagan's day it certainly was.