The Entropy of a Binary Hidden Markov Process

The entropy of a binary symmetric Hidden Markov Process is calculated as an expansion in the noise parameter epsilon. We map the problem onto a one-dimensional Ising model in a large field of random signs and calculate the expansion coefficients up to second order in epsilon. Using a conjecture we extend the calculation to 11th order and discuss the convergence of the resulting series

The Best of PALS

Prospective lawyers are not the only ones who lack role models, these days

Ugly as SIN

As I said, not so long ago women were a rather scarce commodity in our firm

A bright, pulsed two-mode squeezer

We report the realization of a bright ultrafast two-mode squeezer based on type II parametric downconversion (PDC) in periodically poled $\mathrm{KTiOPO_4}$ (PP-KTP) waveguides. It produces a pulsed two-mode squeezed vacuum state: a photon-number entangled pair of truly single-mode pulses or, in terms of continuous variables quantum optics, a pulsed, single mode Einstein-Podolsky-Rosen (EPR) state in the telecom regime. We prove the single mode character of our source by measuring its $g^{(2)}$ correlation function and demonstrate a mean photon number of up to 2.5 per pulse, equivalent to 11dB of two-mode squeezing.Comment: 4 pages, 3 figure

Statistical Mechanics of Community Detection

Starting from a general \textit{ansatz}, we show how community detection can be interpreted as finding the ground state of an infinite range spin glass. Our approach applies to weighted and directed networks alike. It contains the \textit{at hoc} introduced quality function from \cite{ReichardtPRL} and the modularity $Q$ as defined by Newman and Girvan \cite{Girvan03} as special cases. The community structure of the network is interpreted as the spin configuration that minimizes the energy of the spin glass with the spin states being the community indices. We elucidate the properties of the ground state configuration to give a concise definition of communities as cohesive subgroups in networks that is adaptive to the specific class of network under study. Further we show, how hierarchies and overlap in the community structure can be detected. Computationally effective local update rules for optimization procedures to find the ground state are given. We show how the \textit{ansatz} may be used to discover the community around a given node without detecting all communities in the full network and we give benchmarks for the performance of this extension. Finally, we give expectation values for the modularity of random graphs, which can be used in the assessment of statistical significance of community structure

Is a multiple excitation of a single atom equivalent to a single excitation of an ensemble of atoms?

Recent technological advances have enabled to isolate, control and measure the properties of a single atom, leading to the possibility to perform statistics on the behavior of single quantum systems. These experiments have enabled to check a question which was out of reach previously: Is the statistics of a repeatedly excitation of an atom N times equivalent to a single excitation of an ensemble of N atoms? We present a new method to analyze quantum measurements which leads to the postulation that the answer is most probably no. We discuss the merits of the analysis and its conclusion.Comment: 3 pages, 3 figure

Finite size effects and error-free communication in Gaussian channels

The efficacy of a specially constructed Gallager-type error-correcting code to communication in a Gaussian channel is being examined. The construction is based on the introduction of complex matrices, used in both encoding and decoding, which comprise sub-matrices of cascading connection values. The finite size effects are estimated for comparing the results to the bounds set by Shannon. The critical noise level achieved for certain code-rates and infinitely large systems nearly saturates the bounds set by Shannon even when the connectivity used is low

How to Use Crowdfunding in Extension: A Relationship Education Example

Crowdfunding is a resource that allows individuals or groups to raise funds while simultaneously engaging relevant communities and, thus, is an important tool for Extension specialists. We provide recommended steps for successful crowdfunding, including tips for identifying a website, developing or refining a proposal, and crafting a marketing and campaign strategy. We use the successful crowdfunding of a relationship education program as an example

Low-Energy Nondipole Effects in Molecular Nitrogen Valence-Shell Photoionization

Observations are reported for the first time of significant nondipole effects in the photoionization of the outer-valence orbitals of diatomic molecules. Measured nondipole angular-distribution parameters for the 3sigmag, 1piu, and 2sigmau shells of N2 exhibit spectral variations with incident photon energies from thresholds to ~200 eV which are attributed via concomitant calculations to particular final-state symmetry waves arising from (E1)[direct-product](M1,E2) radiation-matter interactions first-order in photon momentum. Comparisons with previously reported K-edge studies in N2 verify linear scaling with photon momentum, accounting in part for the significantly enhanced nondipole behavior observed in inner-shell ionization at correspondingly higher momentum values in this molecule

Effect of Nigella sativa L. on heart rate and some haematological values of alloxan-induced diabetic rabbits

This study was designed to investigate the effect of an extract of Nigella sativa L. on the heart rate and  some haematological values in alloxan-induced diabetic rabbits. Fifteen New Zealand male rabbits were  divided into three experimental groups: control, diabetic and N. sativa L.-treated diabetic. At the end of the  experimental period (2 months), animals in all three groups were fasted for 12 hours and blood samples  were taken for the determination of glucose levels, RBC and WBC (red and white blood cell) counts,  packed cell volume (PCV), and haemoglobin (Hb) concentration. Heart rates were also measured by a  direct-writing electrocardiograph before the blood withdrawals. It was found that N. sativa L. treatment  increased the lowered RBC and WBC counts, PCV and neutrophil percentage in diabetic rabbits. However,  the WBC count of the N. sativa L. treated diabetic group was still lower than the control. N. sativa L.  treatment also decreased the elevated heart rate and glucose concentration of diabetic rabbits. It is concluded  that oral N. sativa L. treatment might decrease the diabetes-induced disturbances of heart rate and some  haematological parameters of alloxan-induced diabetic rabbits.