Telescoping Sums, Permutations, and First Occurrence Distributions

Telescoping sums very naturally lead to probability distributions on ${\mathbb Z}^+$. But are these distributions typically cosmetic and devoid of motivation? In this paper we give three examples of "first occurrence" distributions, each defined by telescoping sums, and that each arise from concrete questions about the structure of permutations.Comment: 13 page

Submarket, Heterogeneity and Hedonic Prediction Accuracy of Real Estate Prices: Evidence from Shanghai

This paper contributes to the literature by examining how much the prediction accuracy of real estate prices could be improved by applying hedonic equations at suitably defined disaggregate levels and incorporating directional heterogeneity of distance gradients. We build our empirical analysis on a large-scale database of real estate projects sold between 2005 and 2007 in Shanghai. Our analysis suggests that the Shanghai real estate market is a complex aggregate and taking into account submarket and directional heterogeneity in hedonic regressions could provide considerable benefits in improving the precision of real estate price predictions.Hedonic analysis; Prediction accuracy; Submarket

Pulsar interpretation of the lepton spectra measured by AMS-02

AMS-02 recently published its lepton spectra measurement. The results show that the positron fraction no longer increases above $\sim$200 GeV. The aim of this work is to investigate the possibility that the excess of positron fraction is due to pulsars. Nearby known pulsars from ATNF catalogue are considered as a possible primary positron source of the high energy positrons. We find that the pulsars with age $T\simeq (0.45\sim4.5)\times10^{5}$ yr and distance $d<0.5$ kpc can explain the behavior of positron fraction of AMS-02 in the range of high energy. We show that each of the four pulsars --- Geminga, J1741-2054, Monogem and J0942-5552 --- is able to be a single source satisfying all considered physical requirements. We also discuss the possibility that these high energy $e^{\pm}$ are from multiple pulsars. The multiple pulsars contribution predicts a positron fraction with some structures at higher energies.Comment: 27 pages, 5 figures, 3 tables, accepted for publication in EPJ