What the Phub?

“Nobody talks to each other anymore.” When my grandfather said this as we sped down the highway, I wondered what to make of it. Is he simply being a negative elderly man, or is there some truth to the statement? Considering that I had been trying to tune out his questions with my headphones the whole drive, I guess I deserved some type of scolding. As his questions were repeated, my mother pointed out to my grandfather that I could not hear him, to which he shook his head and said, “Nobody talks to each other anymore.” Finally, I put aside my sour mood and took off my headphones, answering his questions about college life and my general wellbeing. [excerpt

Detecting planets in protoplanetary disks: A prospective study

We investigate the possibility to find evidence for planets in circumstellar disks by infrared and submillimeter interferometry. We present simulations of a circumstellar disk around a solar-type star with an embedded planet of 1 Jupiter mass. The three-dimensional (3D) density structure of the disk results from hydrodynamical simulations. On the basis of 3D radiative transfer simulations, images of this system were calculated. The intensity maps provide the basis for the simulation of the interferometers VLTI (equipped with the mid-infrared instrument MIDI) and ALMA. While MIDI/VLTI will not provide the possibility to distinguish between disks with or without a gap on the basis of visibility measurements, ALMA will provide the necessary basis for a direct gap detection.Comment: 5 page

Middle East water conflicts and directions for conflict resolution:

In looking toward 2020, one of the most severe problems to be faced is an impending shortage of adequate supplies of fresh water essential for drinking and for growing crops. The Middle East, where a few waterways serve large areas of land belonging to a number of nations, is the place where strife over water is most likely to erupt. This paper examines the past how water in the Middle East came to be divided as it is today and looks at possible solutions for alleviating a water crisis and the resulting political tensions.Water resources development Middle East., Water-supply Middle East Management.,

The true complexity of a system of linear equations

It is well-known that if a subset A of a finite Abelian group G satisfies a quasirandomness property called uniformity of degree k, then it contains roughly the expected number of arithmetic progressions of length k, that is, the number of progressions one would expect in a random subset of G of the same density as A. One is naturally led to ask which degree of uniformity is required of A in order to control the number of solutions to a general system of linear equations. Using so-called "quadratic Fourier analysis", we show that certain linear systems that were previously thought to require quadratic uniformity are in fact governed by linear uniformity. More generally, we conjecture a necessary and sufficient condition on a linear system L which guarantees that any subset A of F_p^n which is uniform of degree k contains the expected number of solutions to L.Comment: 30 page

Conflict and Cooperation Over Transboundary Waters

human development, water, sanitation

Linear forms and higher-degree uniformity for functions on Fpn\mathbb{F}_p^n

In [GW09a] we conjectured that uniformity of degree $k-1$ is sufficient to control an average over a family of linear forms if and only if the $k$th powers of these linear forms are linearly independent. In this paper we prove this conjecture in $\mathbb{F}_p^n$, provided only that $p$ is sufficiently large. This result represents one of the first applications of the recent inverse theorem for the $U^k$ norm over $\mathbb{F}_p^n$ by Bergelson, Tao and Ziegler [BTZ09,TZ08]. We combine this result with some abstract arguments in order to prove that a bounded function can be expressed as a sum of polynomial phases and a part that is small in the appropriate uniformity norm. The precise form of this decomposition theorem is critical to our proof, and the theorem itself may be of independent interest.Comment: 40 page