Path separation by short cycles

Two Hamilton paths in $K_n$ are separated by a cycle of length $k$ if their union contains such a cycle. For small fixed values of $k$ we bound the asymptotics of the maximum cardinality of a family of Hamilton paths in $K_n$ such that any pair of paths in the family is separated by a cycle of length $k.$Comment: final version with correction

Exponents and bounds for uniform spanning trees in d dimensions

Uniform spanning trees are a statistical model obtained by taking the set of all spanning trees on a given graph (such as a portion of a cubic lattice in d dimensions), with equal probability for each distinct tree. Some properties of such trees can be obtained in terms of the Laplacian matrix on the graph, by using Grassmann integrals. We use this to obtain exact exponents that bound those for the power-law decay of the probability that k distinct branches of the tree pass close to each of two distinct points, as the size of the lattice tends to infinity.Comment: 5 pages. v2: references added. v3: closed form results can be extended slightly (thanks to C. Tanguy). v4: revisions, and a figure adde

Do disasters affect growth? A macro model-based perspective on the empirical debate

A growing literature has sought to quantify the impacts of natural disasters on economic growth, but has found seemingly contradictory results, ranging from positive to very large negative effects. This paper brings a novel macroeconomic model-based perspective to the data. We present a stochastic endogenous growth model where individual regions face uninsurable cyclone risks to human and entrepreneurial capital, building on the tools developed in the incomplete markets macroeconomics literature (Krebs, 2003, Angeletos, 2007). Our model can reconcile key divergent results from prior empirical studies, as they measure different elements of the overall impact of disasters on growth: (1) Higher disaster risk can increase growth by increasing (precautionary) savings, whereas disaster strikes induce (potentially persistent) output losses, in line with the empirical evidence of positive growth effects in cross-sectional analyses (e.g., Skidmore and Toya, 2002) but negative impacts in panel studies (e.g., Hsiang and Jina, 2015a). We explore a combined two-step estimation to assess the overall impact of cyclones on growth, which - on average - appears to lie in between. (2) Competing measures of cyclone risk - average capital destruction, fatalities, or storm intensity - can be related to growth in opposite ways, again in line with the literature (e.g., Hsiang and Jina, 2015b vs. Skidmore and Toya, 2002). Intuitively, long-run growth depends on the level and composition of investments across different assets, which, in turn, depend differentially on the vector of expected damages to all capital goods. (3) Finally, we show that disaster risk can have opposite effects on growth and welfare

A generalization of bounds for cyclic codes, including the HT and BS bounds

We use the algebraic structure of cyclic codes and some properties of the discrete Fourier transform to give a reformulation of several classical bounds for the distance of cyclic codes, by extending techniques of linear algebra. We propose a bound, whose computational complexity is polynomial bounded, which is a generalization of the Hartmann-Tzeng bound and the Betti-Sala bound. In the majority of computed cases, our bound is the tightest among all known polynomial-time bounds, including the Roos bound

Radiation effects on silicon second quarterly progress report, sep. 1 - nov. 30, 1964

Electron spin resonance measurements on P-doped silicon - vacancy phosphorus defec

Radiation effects on silicon third quarterly progress report, dec. 1, 1964 - feb. 28, 1965

Radiation effect on silicon - introduction rates of vacancy-phosphorus defect and divacancy in p-type material for solar cell applicatio