Switching the spin cycloid in BiFeO3 with an electric field.

Bismuth ferrite (BiFeO3) is a multiferroic material that exhibits both ferroelectricity and canted antiferromagnetism at room temperature, making it a unique candidate in the development of electric-field controllable magnetic devices. The magnetic moments in BiFeO3 are arranged into a spin cycloid, resulting in unique magnetic properties which are tied to the ferroelectric order. Previous understanding of this coupling has relied on average, mesoscale measurements. Using nitrogen vacancy-based diamond magnetometry, we observe the magnetic spin cycloid structure of BiFeO3 in real space. This structure is magnetoelectrically coupled through symmetry to the ferroelectric polarization and this relationship is maintained through electric field switching. Through a combination of in-plane and out-of-plane electrical switching, coupled with ab initio studies, we have discovered that the epitaxy from the substrate imposes a magnetoelastic anisotropy on the spin cycloid, which establishes preferred cycloid propagation directions. The energy landscape of the cycloid is shaped by both the ferroelectric degree of freedom and strain-induced anisotropy, restricting the spin spiral propagation vector to changes to specific switching events.

The Role of Alkalis in Orchestrating Uranyl-Peroxide Reactivity Leading to Direct Air Capture of Carbon Dioxide.

Spectator ions have known and emerging roles in aqueous metal-cation chemistry, respectively directing solubility, speciation, and reactivity. Here, we isolate and structurally characterize the last two metastable members of the alkali uranyl triperoxide series, the Rb+ and Cs+ salts (Cs-U1 and Rb-U1). We document their rapid solution polymerization via small-angle X-ray scattering, which is compared to the more stable Li+, Na+ and K+ analogues. To understand the role of the alkalis, we also quantify alkali-hydroxide promoted peroxide deprotonation and decomposition, which generally exhibits increasing reactivity with increasing alkali size. Cs-U1, the most unstable of the uranyl triperoxide monomers, undergoes ambient direct air capture of CO2 in the solid-state, converting to Cs4[UVIO2(CO3)3], evidenced by single-crystal X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. We have attempted to benchmark the evolution of Cs-U1 to uranyl tricarbonate, which involves a transient, unstable hygroscopic solid that contains predominantly pentavalent uranium, quantified by X-ray photoelectron spectroscopy. Powder X-ray diffraction suggests this intermediate state contains a hydrous derivative of CsUVO3, where the parent phase has been computationally predicted, but not yet synthesized.

Quark Mass Dependence of Heavy Quark Diffusion Coefficient from Lattice QCD.

We present the first study of the quark mass dependence of the heavy quark momentum and spatial diffusion coefficients using lattice QCD with light dynamical quarks corresponding to a pion mass of 320 MeV. We find that, for the temperature range 195 MeV

Second-Order Hydrodynamics in Next-to-Leading-Order QCD.

We compute the hydrodynamic relaxation times τ_{π} and τ_{j} for hot QCD at next-to-leading order in the coupling with kinetic theory. We show that certain dimensionless ratios of second-order to first-order transport coefficients obey bounds which apply whenever a kinetic theory description is possible; the computed values lie somewhat above these bounds. Strongly coupled theories with holographic duals strongly violate these bounds, highlighting their distance from a quasiparticle description.

Seroepidemiology of Bartonella infection in gray foxes from Texas.

Gray foxes (Urocyon cinereoargenteus) were shown to be naturally infected with Bartonella rochalimae, a Bartonella species similar to Bartonella clarridgeiae (B.c.), and Bartonella vinsonii subspecies berkhoffii (B.v.berkhoffii) in northern California. A serological survey was performed to investigate the presence of Bartonella infection in 132 gray foxes from West/Central Texas. Using an immunofluorescence antibody test directed against B.v.berkhoffii and B.c., the antibody prevalence was 50% (66/132), with 22 (33.3%) individuals seropositive for B.c. only, 8 (12.2%) for B.v.berkhoffii, and 36 (54.5%) seroreactive for both B.c. and B.v.berkhoffii. The foxes had 3.63 more odds (95% confidence interval [CI]=1.38, 10.25) to be seropositive for B.c. than for B.v.berkhoffii. Female foxes were more likely to be seropositive for B.c. (odds ratio [OR]=2.90, 95% CI=1.33, 6.36) and also for both antigens (OR=2.50, 95% CI=1.06, 5.90) than males.

Kubo formulas for second-order hydrodynamic coefficients.

At second order in gradients, conformal relativistic hydrodynamics depends on the viscosity η and on five additional "second-order" hydrodynamical coefficients τ(Π), κ, λ1, λ2, and λ3. We derive Kubo relations for these coefficients, relating them to equilibrium, fully retarded three-point correlation functions of the stress tensor. We show that the coefficient λ3 can be evaluated directly by Euclidean means and does not in general vanish.

Heavy quark diffusion in perturbative QCD at next-to-leading order.

We compute the momentum diffusion coefficient of a heavy quark in a hot QCD plasma, to next-to-leading order in the weak-coupling expansion. Corrections arise at [see formula]; physically they represent interference between overlapping scatterings, as well as soft, electric scale (p approximately gT) gauge field physics, which we treat using the hard thermal loop effective theory. In 3-color, 3-flavor QCD, the momentum diffusion constant of a fundamental representation heavy quark at next-to-leading order is kappa = 16pi/3alpha(s)(2)T(3)(ln1/g(s)+0.07428+1.9026 g(s)). The convergence of the perturbative expansion is poor.

Radiative and collisional jet energy loss in the quark-gluon plasma at the BNL relativistic heavy ion collider.

We calculate and compare bremsstrahlung and collisional energy loss of hard partons traversing a quark-gluon plasma. Our treatment of both processes is complete at leading order in the coupling and accounts for the probabilistic nature of the jet energy loss. We find that the nuclear modification factor R(AA) for neutral pi(0) production in heavy ion collisions is sensitive to the inclusion of collisional and radiative energy loss contributions while the averaged energy loss only slightly increases if collisional energy loss is included for parent parton energies E>>T. These results are important for the understanding of jet quenching in Au+Au collisions at 200A GeV at the Relativistic Heavy Ion Collider (RHIC). Comparison with data is performed applying the energy loss calculation to a relativistic ideal (3+1)-dimensional hydrodynamic description of the thermalized medium formed at RHIC.

Evaluation of oral rabies vaccination programs for control of rabies epizootics in coyotes and gray foxes: 1995-2003.

OBJECTIVE: To evaluate the effectiveness of intervention efforts to halt 2 wildlife rabies epizootics from 1995 through 2003, including 9 oral rabies vaccination campaigns for coyotes and 8 oral rabies vaccination campaigns for gray foxes. DESIGN: Retrospective study. ANIMALS: 98 coyotes during prevaccination surveillance and 963 coyotes and 104 nontarget animals during postvaccination surveillance in south Texas, and 699 gray foxes and 561 nontarget animals during postvaccination surveillance in west-central Texas. PROCEDURES: A recombinant-virus oral rabies vaccine in edible baits was distributed by aircraft for consumption by coyotes and gray foxes. Bait acceptance was monitored by use of microscopic analysis of tetracycline biomarker in upper canine teeth and associated bone structures in animals collected for surveillance. Serologic responses were monitered by testing sera for rabies virus-neutralizing antibodies by use of the rapid fluorescent focus inhibition test. The incidence of rabies in the distribution area was recorded via active and passive surveillance activities; tracking of rabies virus variants in confirmed rabid animals was used to determine the number and type of rabies cases before and after distributions of the vaccine. RESULTS: The expansion of both epizootics was halted as a result of the vaccine bait program. The number of laboratory-confirmed rabid animals attributable to the domestic dog-coyote rabies virus variant in south Texas declined to 0, whereas the number of laboratory-confirmed rabid animals attributable to the Texas fox rabies virus variant in west-central Texas decreased. CONCLUSIONS AND CLINICAL RELEVANCE: Data indicated that oral rabies vaccination resulted in protective immunity in a sufficient percentage of the target wildlife population to preclude propagation of the disease and provided an effective means of controlling rabies in these species.

Apparent thermalization due to plasma instabilities in the quark-gluon plasma.

Hydrodynamical modeling of heavy-ion collisions at RHIC suggests that the quark-gluon plasma (QGP) "thermalizes" in a remarkably short time scale, about 0.6 fm/c. We argue that this should be viewed as indicating fast isotropization, but not necessarily complete thermalization, of the nonequilibrium QGP. Non-Abelian plasma instabilities can drive local isotropization of an anisotropic QGP on a time scale which is faster than ordinary perturbative scattering processes. As a result, we argue that theoretical expectations based on weak-coupling analysis are not necessarily in conflict with hydrodynamic modeling of the early part of RHIC collisions, provided one recognizes the key role of non-Abelian plasma instabilities.