Fractals and Scars on a Compact Octagon

A finite universe naturally supports chaotic classical motion. An ordered fractal emerges from the chaotic dynamics which we characterize in full for a compact 2-dimensional octagon. In the classical to quantum transition, the underlying fractal can persist in the form of scars, ridges of enhanced amplitude in the semiclassical wave function. Although the scarring is weak on the octagon, we suggest possible subtle implications of fractals and scars in a finite universe.Comment: 6 pages, 3 figs, LaTeX fil

Intelligence Whistleblower Protections: In Brief

Intelligence whistleblowers are generally Intelligence Community (IC) employees or contractors who bring to light allegations of agency wrongdoings by, for example, disclosing information on such wrongdoings to congressional intelligence committees. Such disclosures can aid oversight of, or help curb misconduct within, intelligence agencies. However, intelligence whistleblowers could face retaliation from their employers for their disclosures, and the fear of such retaliation may deter whistleblowing. Congress and President Obama have taken measures to protect certain intelligence whistleblowers from retaliation, and thereby seemingly encourage these whistleblowers to disclose information on agency wrongdoing. These measures are the Intelligence Community Whistleblower Protection Act of 1998 (ICWPA), Presidential Policy Directive 19 (PPD-19), and Title VI of the Intelligence Authorization Act of 2014 (Title VI). Each of these measures details what disclosures fall within the scope of its protections, which generally include certain disclosures through government channels (e.g., disclosures to agency inspectors general or congressional intelligence committees). None of these measures protect against retaliation or potential criminal liability arising from disclosures to media sources. The ICWPA applies to both IC employees and contractors, whereas PPD-19 and Title VI appear to apply only to IC employees. The ICWPA is the oldest of the three intelligence whistleblower protections and, of the three, provides the least amount of protection to those falling within its scope. The ICWPA does not explicitly prohibit retaliation against IC whistleblowers. Rather, it outlines procedures through which whistleblowers can disclose to the congressional intelligence committees information on “urgent concerns,” such as violations of law or false statements to Congress. The ICWPA further contains no explicit mechanism for obtaining a remedy for retaliation stemming from disclosure of an urgent concern to Congress. It merely allows an IC whistleblower who has faced an adverse personnel action because he disclosed an urgent concern to the congressional intelligence committees to then use the ICWPA’s disclosure procedures to inform the committees of the retaliation. PPD-19, unlike the ICWPA, expressly prohibits an IC employee from taking an adverse personnel action or security clearance determination against another employee because of a protected disclosure. It additionally requires intelligence agencies to develop procedures for internally investigating, through agency Inspectors General, allegations of impermissible retaliation. After finding that impermissible retaliation has occurred, Inspectors General can recommend that agency heads take corrective action. When an employee has exhausted the internal review procedures that must be established under PPD-19, he can appeal to the Director of National Intelligence, who then has the discretion to convene a review panel. If it finds that improper retaliation occurred, the review panel can recommend that the agency head take remedial action. Title VI seemingly codifies, and expands upon, some of the protections of PPD-19. Its protections, and modes of enforcement, differ depending on the type of retaliation alleged. More specifically, Title VI’s protected disclosures and enforcement methods in the context of allegations of adverse personnel action are distinct from its protected disclosures and enforcement methods for allegations of adverse security clearance or information access determinations

Post-digital humanities: computation and cultural critique in the arts and humanities

Today we live in computational abundance whereby our everyday lives and the environment that surrounds us are suffused with digital technologies. This is a world of anticipatory technology and contextual computing that uses smart diffused computational processing to create a fine web of computational resources that are embedded into the material world. Thus, the historical distinction between the digital and the non-digital becomes increasingly blurred, to the extent that to talk about the digital presupposes an experiential disjuncture that makes less and less sense. Indeed, just as the ideas of “online” or “being online” have become anachronistic as a result of our always-on smartphones and tablets and widespread wireless networking technologies, so too the term “digital” perhaps assumes a world of the past

A polyphonic acoustic vortex and its complementary chords

Using an annular phased array of eight loudspeakers, we generate sound beams that simultaneously contain phase singularities at a number of different frequencies. These frequencies correspond to different musical notes and the singularities can be set to overlap along the beam axis, creating a polyphonic acoustic vortex. Perturbing the drive amplitudes of the speakers means that the singularities no longer overlap, each note being nulled at a slightly different lateral position, where the volume of the other notes is now nonzero. The remaining notes form a tri-note chord. We contrast this acoustic phenomenon to the optical case where the perturbation of a white light vortex leads to a spectral spatial distribution

Geometric phases and anholonomy for a class of chaotic classical systems

Berry's phase may be viewed as arising from the parallel transport of a quantal state around a loop in parameter space. In this Letter, the classical limit of this transport is obtained for a particular class of chaotic systems. It is shown that this ``classical parallel transport'' is anholonomic --- transport around a closed curve in parameter space does not bring a point in phase space back to itself --- and is intimately related to the Robbins-Berry classical two-form.Comment: Revtex, 11 pages, no figures

Quantum Spectra of Triangular Billiards on the Sphere

We study the quantal energy spectrum of triangular billiards on a spherical surface. Group theory yields analytical results for tiling billiards while the generic case is treated numerically. We find that the statistical properties of the spectra do not follow the standard random matrix results and their peculiar behaviour can be related to the corresponding classical phase space structure.Comment: 18 pages, 5 eps figure

Phase Space Evolution and Discontinuous Schr\"odinger Waves

The problem of Schr\"odinger propagation of a discontinuous wavefunction -diffraction in time- is studied under a new light. It is shown that the evolution map in phase space induces a set of affine transformations on discontinuous wavepackets, generating expansions similar to those of wavelet analysis. Such transformations are identified as the cause for the infinitesimal details in diffraction patterns. A simple case of an evolution map, such as SL(2) in a two-dimensional phase space, is shown to produce an infinite set of space-time trajectories of constant probability. The trajectories emerge from a breaking point of the initial wave.Comment: Presented at the conference QTS7, Prague 2011. 12 pages, 7 figure

Reflectionless Potentials and PT Symmetry

Large families of Hamiltonians that are non-Hermitian in the conventional sense have been found to have all eigenvalues real, a fact attributed to an unbroken PT symmetry. The corresponding quantum theories possess an unconventional scalar product. The eigenvalues are determined by differential equations with boundary conditions imposed in wedges in the complex plane. For a special class of such systems, it is possible to impose the PT-symmetric boundary conditions on the real axis, which lies on the edges of the wedges. The PT-symmetric spectrum can then be obtained by imposing the more transparent requirement that the potential be reflectionless.Comment: 4 Page

Runway grooving project at Chicago Midway Airport

Runway grooving project at Chicago Midway Airpor

Statistical Properties of Many Particle Eigenfunctions

Wavefunction correlations and density matrices for few or many particles are derived from the properties of semiclassical energy Green functions. Universal features of fixed energy (microcanonical) random wavefunction correlation functions appear which reflect the emergence of the canonical ensemble as the number of particles approaches infinity. This arises through a little known asymptotic limit of Bessel functions. Constraints due to symmetries, boundaries, and collisions between particles can be included.Comment: 13 pages, 4 figure