Solitonic Brane Inflation

We present a new type of brane inflation motivated by multi-kink solitonic solutions of a scalar field in five dimensions. In the thin brane limit, we analyze a non-static configuration in which the distance between two parallel domain walls decreases. We show that the ensuing spacetime is inflationary, both on the branes, and, for certain potentials, in the bulk. We argue that this inflationary regime is transitory and can end via a brane merger into a single kink solution - a flat, thick brane RS2 universe. This scenario is quite general; we show that any potential which supports a single flat kink solution is also likely to support an inflationary multi-kink configuration.Comment: 15 pages, 3 figures; v.2: journal versio

K-ary n-cube based off-chip communications architecture for high-speed packet processors

A k-ary n-cube interconnect architecture is proposed, as an off-chip communications architecture for line cards, to increase the throughput of the currently used memory system. The k-ary n-cube architecture allows multiple packet processing elements on a line card to access multiple memory modules. The main advantage of the proposed architecture is that it can sustain current line rates and higher while distributing the load among multiple memories. Moreover, the proposed interconnect can scale to adopt more memories and/or processors and as a result increasing the line card processing power. Our results portray that k-ary n-cube sustained higher incoming traffic load while keeping latency lower than its shared-bus competitor. © 2005 IEEE

Large-Scale Calculations of the Double-Beta Decay of 76Ge, 130Te, 136Xe, and 150Nd in the Deformed Self-Consistent Skyrme Quasiparticle Random-Phase Approximation

We use the axially-deformed Skyrme Quasiparticle Random-Phase Approximation (QRPA) together with the SkM* energy-density functional, both as originally presented and with the time-odd part adjusted to reproduce the Gamow-Teller resonance energy in 208Pb, to calculate the matrix elements governing the neutrinoless double-beta decay of 76Ge, 130Te, 136Xe, and 150Nd. Our matrix elements in 130Te and 136Xe are significantly smaller than those of previous QRPA calculations, primarily because of the difference in pairing or deformation between the initial and final nuclei. In 76Ge and 150Nd our results are similar to those of less computationally intensive QRPA calculations. We suspect the 76Ge result, however, because we are forced to use a spherical ground-state, even though the HFB indicates a deformed minimum.Comment: 9 pages, 4 figure

Privacy as a Public Good

Privacy is commonly studied as a private good: my personal data is mine to protect and control, and yours is yours. This conception of privacy misses an important component of the policy problem. An individual who is careless with data exposes not only extensive information about herself, but about others as well. The negative externalities imposed on nonconsenting outsiders by such carelessness can be productively studied in terms of welfare economics. If all relevant individuals maximize private benefit, and expect all other relevant individuals to do the same, neoclassical economic theory predicts that society will achieve a suboptimal level of privacy. This prediction holds even if all individuals cherish privacy with the same intensity. As the theoretical literature would have it, the struggle for privacy is destined to become a tragedy. But according to the experimental public-goods literature, there is hope. Like in real life, people in experiments cooperate in groups at rates well above those predicted by neoclassical theory. Groups can be aided in their struggle to produce public goods by institutions, such as communication, framing, or sanction. With these institutions, communities can manage public goods without heavy-handed government intervention. Legal scholarship has not fully engaged this problem in these terms. In this Article, we explain why privacy has aspects of a public good, and we draw lessons from both the theoretical and the empirical literature on public goods to inform the policy discourse on privacy

Finite Amplitude Method for Charge-Changing Transitions in Axially-Deformed Nuclei

We describe and apply a version of the finite amplitude method for obtaining the charge-changing nuclear response in the quasiparticle random phase approximation. The method is suitable for calculating strength functions and beta-decay rates, both allowed and forbidden, in axially-deformed open-shell nuclei. We demonstrate the speed and versatility of the code through a preliminary examination of the effects of tensor terms in Skyrme functionals on beta decay in a set of spherical and deformed open-shell nuclei. Like the isoscalar pairing interaction, the tensor terms systematically increase allowed beta-decay rates. This finding generalizes previous work in semimagic nuclei and points to the need for a comprehensive study of time-odd terms in nuclear density functionals.Comment: 11 pages, 8 figures, submitted to Physical Review

Limit on T-violating P-conserving rhoNN interaction from the gamma decay of Fe-57

We use the experimental limit on the interference of M1 and E2 multipoles in the γ decay of 57Fe to bound the time-reversal-violating parity-conserving ρNN vertex. Our approach is a large-basis shell-model calculation of the interference. We find an upper limit on the parameter g¯ρ, the relative strength of the T-violating ρNN vertex, of close to 10^(-2), a value similar to the best limits from other experiments

Entropic Stabilization of Tunable Planar Modulated Superstructures

Self-assembling novel ordered structures with nanoparticles has recently received much attention. Here we use computer simulations to study a two-dimensional model system characterized by a simple isotropic interaction that could be realized with building blocks on the nanoscale. We find that the particles arrange themselves into hexagonal superstructures of twin boundaries whose superlattice vector can be tuned reversibly by changing the temperature. Thermodynamic stability is confirmed by calculating the free energy with a combination of thermodynamic integration and the Frenkel-Ladd method. Different contributions to the free energy difference are discussed.Comment: 4 pages, 5 figures plus 7 pages of supplementary figure