A Bionic Coulomb Phase on the Pyrochlore Lattice

A class of three dimensional classical lattice systems with macroscopic ground state degeneracies, most famously the spin ice system, are known to exhibit "Coulomb" phases wherein long wavelength correlations within the ground state manifold are described by an emergent Maxwell electrodynamics. We discuss a new example of this phenomenon-the four state Potts model on the pyrochlore lattice-where the long wavelength description now involves three independent gauge fields as we confirm via simulation. The excitations above the ground state manifold are bions, defects that are simultaneously charged under two of the three gauge fields, and exhibit an entropic interaction dictated by these charges. We also show that the distribution of flux loops shows a scaling with loop length and system size previously identified as characteristic of Coulomb phases

The Investment Climate, Competition Policy, and Economic Development in Latin America

The merits of fostering effective competition in the economy to encourage economic efficiency, consumer welfare, productivity, innovation, and attract investment have been increasingly and widely recognized by governments around the world. Relative to other regions, developing countries in Latin America have been at the forefront in adopting pro-competition measures such as deregulating industries, liberalizing trade and investment, and enacting competition (antitrust or antimonopoly) laws. However, the quality of the investment climate that determines the risks and transaction costs associated with investing and operating a business, as well as the implementation of competition law and policy, tend to vary widely across Latin American countries. This article argues that to enhance greater coherency and consistency in these policies, competition law-policy needs to be integrated as a central platform. Doing so will improve and buttress the investment climate prevailing in a country. To attain this requires increased efforts to promote better understanding of the instruments, requirements, and benefits of encouraging competition through competition advocacy —in government economic policy formulation, private sector business decisions, and civil society at large

The Investment Climate, Competition Policy, and Economic Development in Latin America

The merits of fostering effective competition in the economy to encourage economic efficiency, consumer welfare, productivity, innovation, and attract investment have been increasingly and widely recognized by governments around the world. Relative to other regions, developing countries in Latin America have been at the forefront in adopting pro-competition measures such as deregulating industries, liberalizing trade and investment, and enacting competition (antitrust or antimonopoly) laws. However, the quality of the investment climate that determines the risks and transaction costs associated with investing and operating a business, as well as the implementation of competition law and policy, tend to vary widely across Latin American countries. This article argues that to enhance greater coherency and consistency in these policies, competition law-policy needs to be integrated as a central platform. Doing so will improve and buttress the investment climate prevailing in a country. To attain this requires increased efforts to promote better understanding of the instruments, requirements, and benefits of encouraging competition through competition advocacy —in government economic policy formulation, private sector business decisions, and civil society at large

Prethermalization without Temperature

While a clean, driven system generically absorbs energy until it reaches "infinite temperature," it may do so very slowly exhibiting what is known as a prethermal regime. Here, we show that the emergence of an additional approximately conserved quantity in a periodically driven (Floquet) system can give rise to an analogous long-lived regime. This can allow for nontrivial dynamics, even from initial states that are at a high or infinite temperature with respect to an effective Hamiltonian governing the prethermal dynamics. We present concrete settings with such a prethernial regime, one with a period-doubled (time-crystalline) response. We also present a direct diagnostic to distinguish this prethermal phenomenon from its infinitely long-lived many-body localized cousin. We apply these insights to a model of the recent NMR experiments by Rovny et al. [Phys. Rev. Lett. 120, 180603 (2018)] which, intriguingly, detected signatures of a Floquet time crystal in a clean three-dimensional material. We show that a mild but subtle variation of their driving protocol can increase the lifetime of the time-crystalline signal by orders of magnitude

Energies of Quantum QED Flux Tubes

In this talk I present recent studies on vacuum polarization energies and energy densities induced by QED flux tubes. I focus on comparing three and four dimensional scenarios and the discussion of various approximation schemes in view of the exact treatment.Comment: 9 pages latex, Talk presented at the QFEXT 05 workshop in Barcelona, Sept. 2005. To appear in the proceeding

Chemical composition and size distribution of atmospheric aerosols over the Deccan Plateau, India.

Measurements on atmospheric total aerosol were made at Poona during the summer and winter seasons of 1978–79. An Andersen particle sampler Model 20–810, Mark II (Andersen 2000 Inc. U.S.A.) which samples atmospheric particles with diameters ranging between 0.4 and 10.0 μm was used for the measurement. The mass distribution of the total aerosol, and separately for the chloride, sodium, ammonium, sulphate and nitrate components were obtained. The mass distribution of the aerosols exhibited a bimodal distribution in the size ranges 0.4–0.6 μm and 5–6 μm. The chloride and sodium components exhibited by and large a unimodal distribution. The ammonium and sulphate components exhibited a bimodal distribution during the monsoon and a unimodal distribution during the winter. The nitrate component exhibited a bimodal distribution during the monsoon and winter. The molecular form of this component appears to be ammonium nitrate in the sub-micron range and sodium nitrate in the higher size range (1–10 μm)

Numerical Investigation of Monopole Chains

We present numerical results for chains of SU(2) BPS monopoles constructed from Nahm data. The long chain limit reveals an asymmetric behavior transverse to the periodic direction, with the asymmetry becoming more pronounced at shorter separations. This analysis is motivated by a search for semiclassical finite temperature instantons in the 3D SU(2) Georgi-Glashow model, but it appears that in the periodic limit the instanton chains either have logarithmically divergent action or wash themselves out.Comment: 14 pages, 6 figures; v2 minor changes, published versio