Analytical modelling of hot-spot traffic in deterministically-routed k-ary n-cubes

Many research studies have proposed analytical models to evaluate the performance of k-ary n-cubes with deterministic wormhole routing. Such models however have so far been confined to uniform traffic distributions. There has been hardly any model proposed that deal with non-uniform traffic distributions that could arise due to, for instance, the presence of hot-spots in the network. This paper proposes the first analytical model to predict message latency in k-ary n-cubes with deterministic routing in the presence of hot-spots. The validity of the model is demonstrated by comparing analytical results with those obtained through extensive simulation experiments

Superfluid-insulator transitions of two-species Bosons in an optical lattice

We consider a realization of the two-species bosonic Hubbard model with variable interspecies interaction and hopping strength. We analyze the superfluid-insulator (SI) transition for the relevant parameter regimes and compute the ground state phase diagram for odd filling at commensurate densities. We find that in contrast to the even commensurate filling case, the superfluid-insulator transition occurs with (a) simultaneous onset of superfluidity of both species or (b) coexistence of Mott insulating state of one species and superfluidity of the other or, in the case of unit filling, (c) complete depopulation of one species. The superfluid-insulator transition can be first order in a large region of the phase diagram. We develop a variational mean-field method which takes into account the effect of second order quantum fluctuations on the superfluid-insulator transition and corroborate the mean-field phase diagram using a quantum Monte Carlo study.Comment: 12 pages, 11 figure

Controlled and combined remote implementations of partially unknown quantum operations of multiqubits using GHZ states

We propose and prove protocols of controlled and combined remote implementations of partially unknown quantum operations belonging to the restricted sets [An Min Wang: PRA, \textbf{74}, 032317(2006)] using GHZ states. We detailedly describe the protocols in the cases of one qubit, respectively, with one controller and with two senders. Then we extend the protocols to the cases of multiqubits with many controllers and two senders. Because our protocols have to demand the controller(s)'s startup and authorization or two senders together working and cooperations, the controlled and combined remote implementations of quantum operations definitely can enhance the security of remote quantum information processing and potentially have more applications. Moreover, our protocol with two senders is helpful to farthest arrive at the power of remote implementations of quantum operations in theory since the different senders perhaps have different operational resources and different operational rights in practice.Comment: 26 pages, the submitted versio

Constraining the Circumbinary Envelope of Z CMa via imaging polarimetry

Z CMa is a complex binary system, composed of a Herbig Be and an FU Ori star. The Herbig star is surrounded by a dust cocoon of variable geometry, and the whole system is surrounded by an infalling envelope. Previous spectropolarimetric observations have reported a preferred orientation of the polarization angle, perpendicular to the direction of a large, parsec-sized jet associated with the Herbig star. The variability in the amount of polarized light has been associated to changes in the geometry of the dust cocoon that surrounds the Herbig star. We aim to constrain the properties of Z CMa by means of imaging polarimetry at optical wavelengths. Using ExPo, a dual-beam imaging polarimeter which operates at optical wavelengths, we have obtained imaging (linear) polarimetric data of Z CMa. Our observations were secured during the return to quiescence after the 2008 outburst. We detect three polarized features over Z CMa. Two of these features are related to the two jets reported in this system: the large jet associated to the Herbig star, and the micro-jet associated to the FU Ori star. Our results suggest that the micro-jet extends to a distance ten times larger than reported in previous studies. The third feature suggests the presence of a hole in the dust cocoon that surrounds the Herbig star of this system. According to our simulations, this hole can produce a pencil beam of light that we see scattered off the low-density envelope surrounding the system.Comment: Accepted for publication in A\&

The Solar pp and hep Processes in Effective Field Theory

The strategy of modern effective field theory is exploited to pin down accurately the flux $S$ factors for the $pp$ and $hep$ processes in the Sun. The technique used is to combine the high accuracy established in few-nucleon systems of the "standard nuclear physics approach" (SNPA) and the systematic power counting of chiral perturbation theory (ChPT) into a consistent effective field theory framework. Using highly accurate wave functions obtained in the SNPA and working to \nlo3 in the chiral counting for the current, we make totally parameter-free and error-controlled predictions for the $pp$ and $hep$ processes in the Sun.Comment: 5 pages, aipproc macros are included. Talk given at International Nuclear Physics Conference 2001, Berkeley, California, July 30 - August 3, 200

Near-Optimal Distributed Approximation of Minimum-Weight Connected Dominating Set

This paper presents a near-optimal distributed approximation algorithm for the minimum-weight connected dominating set (MCDS) problem. The presented algorithm finds an $O(\log n)$ approximation in $\tilde{O}(D+\sqrt{n})$ rounds, where $D$ is the network diameter and $n$ is the number of nodes. MCDS is a classical NP-hard problem and the achieved approximation factor $O(\log n)$ is known to be optimal up to a constant factor, unless P=NP. Furthermore, the $\tilde{O}(D+\sqrt{n})$ round complexity is known to be optimal modulo logarithmic factors (for any approximation), following [Das Sarma et al.---STOC'11].Comment: An extended abstract version of this result appears in the proceedings of 41st International Colloquium on Automata, Languages, and Programming (ICALP 2014

Superspace Formulation in a Three-Algebra Approach to D=3, N=4,5 Superconformal Chern-Simons Matter Theories

We present a superspace formulation of the D=3, N=4,5 superconformal Chern-Simons Matter theories, with matter supermultiplets valued in a symplectic 3-algebra. We first construct an N=1 superconformal action, and then generalize a method used by Gaitto and Witten to enhance the supersymmetry from N=1 to N=5. By decomposing the N=5 supermultiplets and the symplectic 3-algebra properly and proposing a new super-potential term, we construct the N=4 superconformal Chern-Simons matter theories in terms of two sets of generators of a (quaternion) symplectic 3-algebra. The N=4 theories can also be derived by requiring that the supersymmetry transformations are closed on-shell. The relationship between the 3-algebras, Lie superalgebras, Lie algebras and embedding tensors (proposed in [E. A. Bergshoeff, O. Hohm, D. Roest, H. Samtleben, and E. Sezgin, J. High Energy Phys. 09 (2008) 101.]) is also clarified. The general N=4,5 superconformal Chern-Simons matter theories in terms of ordinary Lie algebras can be rederived in our 3-algebra approach. All known N=4,5 superconformal Chern-Simons matter theories can be recovered in the present superspace formulation for super-Lie-algebra realization of symplectic 3-algebras.Comment: 37 pages, minor changes, published in PR