arXiv subjects

John Taylor

Publications and source records attributed to John Taylor.

22 records · Page 2Linked to original sources

arXiv2012

Updated Results from the RICE Experiment and Future Prospects for Ultra-High Energy Neutrino Detection at the South Pole

The RICE experiment seeks observation of ultra-high energy (UHE; >100 PeV) neutrinos interacting in Antarctic ice, by measurement of the radiowavelength Cherenkov radiation resulting from the collision of a neutrino with an ice molecule. RICE was initiated in 1999 as a first-generation prototype for an eventual, large-scale in-ice UHE neutrino detector. Herein, we present updated limits on the diffuse UHE neutrino flux, based on twelve years of data taken between 1999 and 2010. We find no convincing neutrino candidates, resulting in 95% confidence-level model-dependent limits on the flux which improve on our previous (2006) results by a factor of two. We also report on ice properties' studies, including observation of radiowave reflections from layers internal to the ice sheet. We observe correlations of these reflections with the local ice flow direction, and also qualitatively verify the expected reduction in radio frequency ice transparency with increasing depth/temperature. A new experimental initiative (the Askaryan Radio Array, ARA) commenced at South Pole in 2010-11 will improve the RICE sensitivity (per unit time) by approximately two orders of magnitude.

astro-ph.HE↗

arXiv2008

A Solution to the Monotonicity Problem for Unimodal Families

In this note we consider a collection C of one parameter families of unimodal maps of [0,1]. Each family in the collection has the form uf where u is in [0,1]. Denoting the kneading sequence of uf by K(uf), we will prove that for each member of C, the map u->K(uf) is monotone. It then follows that for each member of C the map u -> h(uf) is monotone, where h(uf) is the topological entropy of uf. For interest, uf(x)=4ux(1-x) and uf(x)=usin(pi x) are shown to belong to C.

math.DS↗

arXiv2007

When will a One Parameter Family of Unimodal Maps Produce Finite Limit Cycles Monotonically with the Parameter?

In this note we consider a collection $\cal{C}$ of one parameter families of unimodal maps of $[0,1].$ Each family in the collection has the form $\{μf\}$ where $μ\in [0,1].$ Denoting the kneading sequence of $μf$ by $K(μf)$, we will prove that for each member of $\cal{C}$, the map $μ\mapsto K(μf)$ is monotone. It then follows that for each member of $\cal{C}$ the map $μ\mapsto h(μf)$ is monotone, where $h(uf)$ is the topological entropy of $μf.$ For interest, $μf(x)=4μx(1-x)$ and $μf(x)=μ\sin(πx)$ are shown to belong to $\cal{C}.$ This extends the work of Masato Tsujii [1].

math.DS↗

arXiv2007

Visualization, Exploration and Data Analysis of Complex Astrophysical Data

In this paper we show how advanced visualization tools can help the researcher in investigating and extracting information from data. The focus is on VisIVO, a novel open source graphics application, which blends high performance multidimensional visualization techniques and up-to-date technologies to cooperate with other applications and to access remote, distributed data archives. VisIVO supports the standards defined by the International Virtual Observatory Alliance in order to make it interoperable with VO data repositories. The paper describes the basic technical details and features of the software and it dedicates a large section to show how VisIVO can be used in several scientific cases.

astro-ph↗