337,587 research outputs found
Ultrabroadband dispersive radiation by spatiotemporal oscillation of multimode waves
Despite the abundance and importance of three-dimensional systems, relatively
little progress has been made on spatiotemporal nonlinear optical waves
compared to time-only or space-only systems. Here we study radiation emitted by
three-dimensionally evolving nonlinear optical waves in multimode fiber.
Spatiotemporal oscillations of solitons in the fiber generate multimode
dispersive wave sidebands over an ultrabroadband spectral range. This work
suggests routes to multipurpose sources of coherent electromagnetic waves, with
unprecedented wavelength coverage.Comment: 13 pages, 3 figures, Supplementary Movie files for preprint available
at: https://www.youtube.com/watch?v=h3meO8G6ZzA and
https://www.youtube.com/watch?v=k42llO-c1r
DIRBE Minus 2MASS: Confirming the Cosmic Infrared Background at 2.2 Microns
Stellar fluxes from the 2MASS catalog are used to remove the contribution due
to Galactic stars from the intensity measured by DIRBE in four regions in the
North and South Galactic polar caps. After subtracting the interplanetary and
galactic foregrounds, a consistent residual intensity of 14.8 +/- 4.6 kJy/sr or
20.2 +/- 6.3 nW/m^2/sr at 2.2 microns is found. At 1.25 microns the residuals
show more scatter and are a much smaller fraction of the foreground, leading to
a weak limit on the CIRB of 12.0 +/- 6.8 kJy/sr or 28.9 +/- 16.3 nW/m^2/sr (1
sigma).Comment: ApJ in press. 14 pages Latex with 7 included figures. accepted
version with 1 new figur
Storytelling snaps
I am curious how a snapshot captures a moment that can trigger a memory and release a tale. My project will be to create a series of digital images and their stories that trace my case study’s life over his eighty years. Through Jim’s archive images I will select photos of his life, show them to him and record stories from his memories. Jim’s self narrative will be my digital storytelling project created to evoke a time and place linking the past into the present. My work is about storytelling through archive photos. This art form has evolved over time with the landscape of computerisation. Our private images and stories are now being shared across public digital media platforms. I can define my passion through the description used by the Centre for Digital Storytelling (1998) “anyone who has a desire to document life experience, ideas, or feelings through the use of story and digital media
Cylinder deformations in orbit closures of translation surfaces
Let M be a translation surface. We show that certain deformations of M
supported on the set of all cylinders in a given direction remain in the
GL(2,R)-orbit closure of M. Applications are given concerning complete
periodicity, field of definition, and the number of of parallel cylinders which
may be found on a translation surface in a given orbit closure.
The proof uses Eskin-Mirzakhani-Mohammadi's recent theorem on orbit closures
of translation surfaces, as well as results of Minsky-Weiss and Smillie-Weiss
on the dynamics of horocycle flow.Comment: v2: Minor revision. Comments welcome! 24 page
The ECHELON Trail: An Illegal Vision
This article tells the story behind the uncovering of the US operated global telecommunications interceptions system now known as ECHELON. It begins with the use of fieldwork techniques in the early 1970's exploring the configuration of Britain's Post Office Towers – these were ostensibly the microwave links through which Britain's long distance telephone calls were made. This modelling process revealed a system within the system of microwave towers linked to the American Base of Menwith Hill in the North York Moors. All the key researchers were then promptly arrested, a raid by Special Branch on the author's university at Lancaster ensued and later a show trail for the other main researchers, most notably Duncan Campbell. Eventually in 1988, Duncan wrote up the ECHELON story, which for its time was an incredible piece of detective work using materials lifted from waste bins by the women activists campaigning around the Menwith Hill Base. Little notice was taken until 1997 when an obscure book by Nicky Hager, Secret Power explained the role and function of ECHELON in more depth. The author represented these findings in a policy report to the European Parliament on the technology of political control that led to a process of political debate and disagreement of the ethics of such a system which continues even today
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