In order to study the density of the set of positive integers d for which the negative Pell equation x2 − dy2 = −1 is solvable in integers, we compute the norm of the fundamental unit in certain well-chosen families of real quadratic orders. A fast algorithm that computes 2-class groups rather than units is used. It is random polynomial-time in log d as the factorization of d is a natural part ...

Let {∞+,∞−} be the two points above ∞ on the real hyperelliptic curve H : y = (x − 1) ∏2g i=1(x− ai). We show that the divisor ([∞ ]− [∞−]) is torsion in Jac J for a dense set of (a1, a2, . . . , a2g) ∈ (−1, 1). In fact, we prove by degeneration to a nodal P that an associated period map has derivative generically of full rank.

When estimating the Doppler frequency, it is common to use a covariance approach. This is especially true for applications such as underwater current profiling . The early developers of this technology made the assumption that the backscattered signal obeyed Gaussian properties. Based on that, a covariance approach have been used for the estimation of the center frequency I the Doppler signal. ...

This paper describes our participation in the TREC 2014 Microblog real-time search task. We investigate whether page views from Wikipedia can be used successfully to estimate relevant time periods for queries. To this end, we use a recently published temporal reranking method by Efron et al. [2], which uses kernel density estimation.

Mineral density of the sternum is insufficiently known. The aim of this research was to investigate mineralisation of the sternum and collect normative data on mineral density of the standard male and female sternum in elderly people (average age of female samples was 64 and male's was 62 years). The research was conducted on 93 cadaveric sternums, 56 male and 37 female samples. To determine re...

Kernel density estimators are the basic tools for density estimation in non-parametric statistics.  The k-nearest neighbor kernel estimators represent a special form of kernel density estimators, in  which  the  bandwidth  is varied depending on the location of the sample points. In this paper‎, we  initially introduce the k-nearest neighbor kernel density estimator in the random left-truncatio...

This work deals with the Traffic State Estimation (TSE) problem for urban networks, using heterogeneous sources of data such as stationary flow sensors, Floating Car Data (FCD), and Automatic Vehicle Identifiers (AVI). A data-based density estimation method is presented tested real traffic data. presents a study case applied to downtown city Grenoble in France, Lab networks (GTL-Ville), which a...