Reactions along the astrophysical s-process path and prospects for neutron radiotherapy with the Liquid-Lithium Target (LiLiT) at the Soreq Applied Research Accelerator Facility (SARAF)

The European Physical Journal A - An empirical formula is proposed for the two-proton decay half-lives. This study is an extension of the empirical formula reported recently by us for calculating...     

An approximation algorithm for maximum triangle packing

We present a randomized -approximation algorithm for the weighted maximum triangle packing problem, for any given ε>0. This is the first algorithm for this problem whose performance guarantee is better than . The algorithm also improves the best-known approximation bound for the maximum 2-edge path packing problem.     

Effects of atmospheric turbulence and building sway on optical wireless-communication systems

Urban optical wireless communication (UOWC) systems are considered a last-mile technology. UOWC systems use the atmosphere as a propagation medium. To provide a line of sight the transceivers are placed on high-rise building. However, dynamic wind loads, thermal expansion, and weak earthquakes cause buildings to sway. These sways distort the alignment between transmitter and receiver, causing pointing errors, the outcome of which is fading of the received signal. Furthermore, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, resulting in impaired link performance. A bit-error probability (BEP) model is developed that takes into account both building sway and turbulence-induced log amplitude fluctuations (i.e., fading of signal intensity) in the regime in which the receiver aperture, D0, is smaller than the turbulence coherence diameter, d0. It is assumed that the receiver has knowledge about the marginal statistics of the signal fading and the instantaneous signal-fading state.     

The Distribution of the Area Under a Bessel Excursion and its Moments

A Bessel excursion is a Bessel process that begins at the origin and first returns there at some given time \(T\) . We study the distribution of the area under such an excursion, which recently found application in the context of laser cooling. The area \(A\) scales with the time as \(A \sim T^{3/2}\) , independent of the dimension, \(d\) , but the functional form of the distribution does depend on \(d\) . We demonstrate that for \(d=1\) , the distribution reduces as expected to the distribution for the area under a Brownian excursion, known as the Airy distribution, deriving a new expression for the Airy distribution in the process. We show that the distribution is symmetric in \(d-2\) , with nonanalytic behavior at \(d=2\) . We calculate the first and second moments of the distribution, as well as a particular fractional moment. We also analyze the analytic continuation from \(d<2\) to \(d>2\) . In the limit where \(d\rightarrow 4\) from below, this analytically continued distribution is described by a one-sided Lévy \(\alpha \) -stable distribution with index \(2/3\) and a scale factor proportional to \([(4-d)T]^{3/2}\) .     

The liquid-lithium target at the soreq applied research accelerator facility

The European Physical Journal A - In stars, the fusion of $$^{22}$$ Ne and $$^4$$ He may produce either $$^{25}$$ Mg, with the emission of a neutron, or $$^{26}$$ Mg and a $$\gamma $$ ray. At high...     

On binding of DNA-bending proteins to DNA minicircles

We present a theoretical study of binding of DNA-bending proteins to circular DNA, using computer simulations of the wormlike chain model of DNA. We find that the binding affinity is affected by the bending elasticity and the conformational entropy of the polymer and that while protein adsorption is identical on open and closed long DNA molecules, there is significant enhancement of binding on DNA minicircles, compared to their linear counterparts. We also find that the ratio of the radii of gyration of open and closed chains depends on protein concentration for short DNA molecules. Experimental tests of our predictions are proposed.     

Dynamic structure factor of vibrating fractals

Motivated by novel experimental work and the lack of an adequate theory, we study the dynamic structure factor S(k,t) of large vibrating fractal networks at large wave numbers k. We show that the decay of S(k,t) is dominated by the spatially averaged mean square displacement of a network node, which evolves subdiffusively in time, ((u[over →](i)(t)-u[over →](i)(0))(2))～t(ν), where ν depends on the spectral dimension d(s) and fractal dimension d(f). As a result, S(k,t) decays as a stretched exponential S(k,t)≈S(k)e(-(Γ(k)t)(ν)) with Γ(k)～k(2/ν). Applications to a variety of fractal-like systems are elucidated.