Caught in the Seamless Web: Does the Internet's Global Reach Justify Less Freedom of Speech?

A federal appellate court will decide this year whether French anti-discrimination law can restrict freedom of speech on U.S.-based websites that are accessible in France. A Paris court ruled in 2000 that the Yahoo! website violated French law because its users offered for sale certain Nazi artifacts. However, to force compliance with the order, French plaintiffs must seek enforcement from a U.S. court. In response, Yahoo! sought a declaratory ruling and a federal district court held that enforcing the French order would violate the First Amendment. The matter is now on appeal. The Yahoo! case presents the question of whether the Internet should be governed by myriad local censorship laws from around the world. U.S. courts have held uniformly that the Internet should receive the highest degree of First Amendment protection. They have been influenced profoundly by the medium's global reach and have invalidated most restrictions so as not to interrupt the "never-ending worldwide conversation" that the Internet makes possible. A contrary result in the Yahoo! case would embrace a very different philosophy -- that Internet speakers must "show their papers" at each nation's borders to ensure that their speech is acceptable to local authorities. Other nations may treat their citizens as fragile children if they wish, or worse, as enemies of the state. But U.S. courts should not permit the seeds of foreign censorship to be planted on U.S. soil by finding that such restrictions are enforceable here

On general flux backgrounds with localized sources

We derive new consistency conditions for string compactifications with generic fluxes (RR, NSNS, geometrical) and localized sources (D-branes, NS-branes, KK-monopoles). The constraints are all related by string dualities and share a common origin in M-theory. We also find new sources of instabilities. We discuss the importance of these conditions for the consistency of the effective action and for the study of interpolating solutions between vacua.Comment: 29 pages, 2 figures, v2: published versio

Canonical bifurcation in higher derivative, higher spin, theories

We present a non-perturbative canonical analysis of the D=3 quadratic-curvature, yet ghost-free, model to exemplify a novel, "constraint bifurcation", effect. Consequences include a jump in excitation count: a linearized level gauge variable is promoted to a dynamical one in the full theory. We illustrate these results with their concrete perturbative counterparts. They are of course mutually consistent, as are perturbative findings in related models. A geometrical interpretation in terms of propagating torsion reveals the model's relation to an (improved) version of Einstein-Weyl gravity at the linearized level. Finally, we list some necessary conditions for triggering the bifurcation phenomenon in general interacting gauge systems.Comment: 10 pages, v2: typos corrected, v3: new title to reflect greatly expanded version, to appear in special issue of J Phys A (eds, M Vasiliev & M Gaberdiel

Lecture Notes on Topological Crystalline Insulators

We give an introduction to topological crystalline insulators, that is, gapped ground states of quantum matter that are not adiabatically connected to an atomic limit without breaking symmetries that include spatial transformations, like mirror or rotational symmetries. To deduce the topological properties, we use non-Abelian Wilson loops. We also discuss in detail higher-order topological insulators with hinge and corner states, and in particular present interacting bosonic models for the latter class of systems.Comment: Lectures given at the San Sebasti\'an Topological Matter School 2017, published in "Topological Matter. Springer Series in Solid-State Sciences, vol 190. Springer, Cham

Forgery in Cyberspace: The Spoof Could Be on You!

Spoofing is one of the newest forms of cyber-attack, a technological methodology adapted to mask the identity of spammers who have faced hostile reaction in response to bulk, unsolicited, electronic mail messages.[1] Sending Spam, however, is no longer the only reason for deception, as crackers have taken pleasure in the challenge of manipulating computer systems and, additionally, find recreational enjoyment in doing so. In this legal Note, the author’s intent is to show that criminal, rather than civil liability is the best way to effectively deter and punish the spoofer. The injury that results when a computer system’s technological safety measures fail to adequately safeguard the system affects not only the owner of the hijacked e-mail address, but also the Internet Service Provider, and the Network as a whole. Current Anti-Spam Legislation is arguably ineffective at targeting these particular types of malicious attacks, and a different legal approach is suggested

Chiral fermions and anomaly cancellation on orbifolds with Wilson lines and flux

We consider six-dimensional supergravity compactified on orbifolds with Wilson lines and bulk flux. Torus Wilson lines are decomposed into Wilson lines around the orbifold fixed points, and twisted boundary conditions of matter fields are related to fractional localized flux. Both, orbifold singularities and flux lead to chiral fermions in four dimensions. We show that in addition to the standard bulk and fixed point anomalies the Green-Schwarz term also cancels the four-dimensional anomaly induced by the flux background. The two axions contained in the antisymmetric tensor field both contribute to the cancellation of the four-dimensional anomaly and the generation of a vector boson mass via the Stueckelberg mechanism. An orthogonal linear combination of the axions remains massless and couples to the gauge field in the standard way. Furthermore, we construct convenient expressions for the wave functions of the zero modes and relate their multiplicity and behavior at the fixed points to the bulk flux quanta and the Wilson lines.Comment: 30 pages, 4 figures, 1 table, clarifying remarks adde

Breaking and restoring symmetries within the nuclear energy density functional method

We review the notion of symmetry breaking and restoration within the frame of nuclear energy density functional methods. We focus on key differences between wave-function- and energy-functional-based methods. In particular, we point to difficulties to formulate the restoration of symmetries within the energy functional framework. The problems tackled recently in connection with particle-number restoration serve as a baseline to the present discussion. Reaching out to angular-momentum restoration, we identify an exact mathematical property of the energy density $E^{LM}(\vec{R})$ that could be used to constrain energy density functional kernels. Consequently, we suggest possible routes towards a better formulation of symmetry restorations within energy density functional methods.Comment: 16 pages, 3 figures, contribution to the "Focus issue on Open Problems in Nuclear Structure", Journal of Physics