8,875 research outputs found
A substructure inside spiral arms, and a mirror image across the Galactic Meridian
While the galactic density wave theory is over 50 years old and well known in
science, whether it fits our own Milky Way disk has been difficult to say. Here
we show a substructure inside the spiral arms. This substructure is reversing
with respect to the Galactic Meridian (longitude zero), and crosscuts of the
arms at negative longitudes appear as mirror images of crosscuts of the arms at
positive longitudes. Four lanes are delineated: mid-arm (extended 12CO gas at
mid arm, HI atoms), in-between offset by about 100 pc (synchrotron, radio
recombination lines), in between offset by about 200 pc (masers, colder dust),
and inner edge (hotter dust seen in Mid-IR and Near-IR).Comment: 25 pages, 2 figures, 10 tables, 1 appendix, accepted 13 February 2016
by Astrophysical Journal (in press
Decision-Making: A Neuroeconomic Perspective
This article introduces and discusses from a philosophical point of view the nascent field of neuroeconomics, which is the study of neural mechanisms involved in decision-making and their economic significance. Following a survey of the ways in which decision-making is usually construed in philosophy, economics and psychology, I review many important findings in neuroeconomics to show that they suggest a revised picture of decision-making and ourselves as choosing agents. Finally, I outline a neuroeconomic account of irrationality
Different studies of the global pitch angle of the Milky Way's spiral arms
There are many published values for the pitch angle of individual spiral
arms, and their wide distribution (from -3 to -28 degrees) begs for various
attempts for a single value. Each of the four statistical methods used here
yields a mean pitch angle in a small range, between -12 and -14 degrees (table
7, figure 2). The final result of our meta-analysis yields a mean global pitch
angle in the Milky Way's spiral arms of -13.1 degrees, plus or minus 0.6
degree.Comment: 18 pages; 2 figures, 7 tables, 1 appendix; accepted on 2015 April 14,
by Monthly Notices of the Royal Astronomical Society (in press
The recurrence function of a random Sturmian word
This paper describes the probabilistic behaviour of a random Sturmian word.
It performs the probabilistic analysis of the recurrence function which can be
viewed as a waiting time to discover all the factors of length of the
Sturmian word. This parameter is central to combinatorics of words. Having
fixed a possible length for the factors, we let to be drawn
uniformly from the unit interval , thus defining a random Sturmian word
of slope . Thus the waiting time for these factors becomes a random
variable, for which we study the limit distribution and the limit density.Comment: Submitted to ANALCO 201
Euclidean algorithms are Gaussian
This study provides new results about the probabilistic behaviour of a class
of Euclidean algorithms: the asymptotic distribution of a whole class of
cost-parameters associated to these algorithms is normal. For the cost
corresponding to the number of steps Hensley already has proved a Local Limit
Theorem; we give a new proof, and extend his result to other euclidean
algorithms and to a large class of digit costs, obtaining a faster, optimal,
rate of convergence. The paper is based on the dynamical systems methodology,
and the main tool is the transfer operator. In particular, we use recent
results of Dolgopyat.Comment: fourth revised version - 2 figures - the strict convexity condition
used has been clarifie
- …