Bubbles created from vacuum fluctuation

We show that the bubbles $S^2\times S^2$can be created from vacuum fluctuation in certain De Sitter universe, so the space-time foam-like structure might really be constructed from bubbles of $S^2\times S^2$ in the very early inflating phase of our universe. But whether such foam-like structure persisted during the later evolution of the universe is a problem unsolved now.Comment: 6 page

An exact solution of spherical mean-field plus orbit-dependent non-separable pairing model with two non-degenerate j-orbits

An exact solution of nuclear spherical mean-field plus orbit-dependent non-separable pairing model with two non-degenerate j-orbits is presented. The extended one-variable Heine-Stieltjes polynomials associated to the Bethe ansatz equations of the solution are determined, of which the sets of the zeros give the solution of the model, and can be determined relatively easily. A comparison of the solution to that of the standard pairing interaction with constant interaction strength among pairs in any orbit is made. It is shown that the overlaps of eigenstates of the model with those of the standard pairing model are always large, especially for the ground and the first excited state. However, the quantum phase crossover in the non-separable pairing model cannot be accounted for by the standard pairing interaction.Comment: 5 pages, 1 figure, LaTe

Excitation of nonlinear ion acoustic waves in CH plasmas

Excitation of nonlinear ion acoustic wave (IAW) by an external electric field is demonstrated by Vlasov simulation. The frequency calculated by the dispersion relation with no damping is verified much closer to the resonance frequency of the small-amplitude nonlinear IAW than that calculated by the linear dispersion relation. When the wave number $k\lambda_{De}$ increases, the linear Landau damping of the fast mode (its phase velocity is greater than any ion's thermal velocity) increases obviously in the region of $T_i/T_e < 0.2$ in which the fast mode is weakly damped mode. As a result, the deviation between the frequency calculated by the linear dispersion relation and that by the dispersion relation with no damping becomes larger with $k\lambda_{De}$ increasing. When $k\lambda_{De}$ is not large, such as $k\lambda_{De}=0.1, 0.3, 0.5$, the nonlinear IAW can be excited by the driver with the linear frequency of the modes. However, when $k\lambda_{De}$ is large, such as $k\lambda_{De}=0.7$, the linear frequency can not be applied to exciting the nonlinear IAW, while the frequency calculated by the dispersion relation with no damping can be applied to exciting the nonlinear IAW.Comment: 10 pages, 9 figures, Accepted by POP, Publication in August 1

Nutrition in cardiovascular disease: salt in hypertension and heart failure

There is much evidence for a causal relationship between salt intake and blood pressure (BP). The current salt intake in many countries is between 9 and 12 g/day. A reduction in salt intake to the recommended level of 5-6 g/day lowers BP in both hypertensive and normotensive individuals. A further reduction to 3-4 g/day has a much greater effect. Prospective studies and outcome trials have demonstrated that a lower salt intake is associated with a decreased risk of cardiovascular disease. Increasing evidence also suggests that a high salt intake is directly related to left ventricular hypertrophy (LVH) independent of BP. Both raised BP and LVH are important risk factors for heart failure. It is therefore possible that a lower salt intake could prevent the development of heart failure. In patients who already have heart failure, a high salt intake aggravates the retention of salt and water, thereby exacerbating heart failure symptoms and progression of the disease. A lower salt intake plays an important role in the management of heart failure. Despite this, currently there is no clear evidence on how far salt intake should be reduced in heart failure. Our personal view is that these patients should reduce their salt intake to <5 g/day, i.e. the maximum intake recommended by the World Health Organisation for all adults. If salt intake is successfully reduced, there may well be a need for a reduction in diuretic dosag

Photosynthetic characterization of a rolled leaf mutant of rice (Oryza sativa L.)

A new rolling leaf rice mutant was identified which showed an apparently straighter longitudinal shape normal transverse rolling characters at all developing stages. The chlorophyll contents per fresh weight of this mutant leaves were lower than those of wild-type. The electron transfer rate (ETR) and photochemical quenching (qP) were a little higher than those of wild-type. However, because of significant increase of non-photochemical quenching (NPQ), the maximal photosystem II (PSII) photochemistry (Fv/Fm) and the efficiency of excitation energy trapping by open PSII reaction centers in the light–adapted state (Fv’/Fm’) were lower than those of wild-type. Low temperature fluorescence analysis showed that rolling leaf mutant assigned more excited energy to photosystem I (PSI) than to PSII. The superoxide dismutase (SOD) content, soluble sugar content, proline content and malonaldehyde (MDA) content of the rolling leaf mutant were nearly 39.4, 91.2, 96.7 and 143.7% of those of wild-type, respectively. The great increase of MDA content suggests that membrane lipid system was damaged in rolling leaf mutant leaves. These results indicate that rolling leaf mutant decrease the efficiency of light utilization compared to the wild-type. This was because of the reduction of leaf area and chlorophyll contents, and the dissipation of more excitation energy as NPQ as a result of avoiding potential damage of membrane structure.Key words: Malonaldehyde (MDA), photosynthetic characterization, rice, rolling leaf mutant

Mastering the Master Space

Supersymmetric gauge theories have an important but perhaps under-appreciated notion of a master space, which controls the full moduli space. For world-volume theories of D-branes probing a Calabi-Yau singularity X the situation is particularly illustrative. In the case of one physical brane, the master space F is the space of F-terms and a particular quotient thereof is X itself. We study various properties of F which encode such physical quantities as Higgsing, BPS spectra, hidden global symmetries, etc. Using the plethystic program we also discuss what happens at higher number N of branes. This letter is a summary and some extensions of the key points of a longer companion paper arXiv:0801.1585.Comment: 10 pages, 1 Figur

Adaptive Vibration Control for an Active Mass Damper of a High-rise Building

As a kind of large flexible structure, high-rise buildings need to consider wind-resistant and anti-seismic problems for the safety of occupants and properties, especially in coastal areas. This paper proposes an infinite dimensional model and an adaptive boundary control law for an active mass damper(AMD) on this question. The dynamic model of the high-rise building is a combination of some storeys which have flexible walls and rigid floors under a series of physical conditions. Then the adaptive boundary controller is acted on an AMD which is equipped on the top floor, in order to suppress the vibration of every floor and guarantee the comfort of residents. Moreover, simulations and experiments are carried out on a two-floor flexible building to illustrate the effectiveness of the proposed control strategy

New Luttinger liquid physics from photoemission on Li0.9_{0.9}Mo6_6O17_{17}

Temperature dependent high resolution photoemission spectra of quasi-1 dimensional Li$_{0.9}$Mo$_6$O$_{17}$ evince a strong renormalization of its Luttinger liquid density-of-states anomalous exponent. We trace this new effect to interacting charge neutral critical modes that emerge naturally from the two-band nature of the material. Li$_{0.9}$Mo$_6$O$_{17}$ is shown thereby to be a paradigm material that is capable of revealing new Luttinger physics.Comment: 4 pages, 3 figures. Accepted for publication by Phys. Rev. Let

Convergence of energy-dependent incommensurate antiferromagnetic neutron scattering peaks to commensurate resonance in underdoped bilayer cuprates

The recently discovered coexistence of incommensurate antiferromagnetic neutron scattering peaks and commensurate resonance in underdoped YBa$_2$Cu$_3$O$_{6+x}$ is calling for an explanation. Within the t-J model, the doping and energy dependence of the spin dynamics of the underdoped bilayer cuprates in the normal state is studied based on the fermion-spin theory by considering the bilayer interactions. Incommensurate peaks are found at $[(1\pm\delta)\pi,\pi]$ and $[\pi,(1\pm\delta)\pi]$ at low energies with $\delta$ initially increasing with doping at low dopings and then saturating at higher dopings. These incommensurate peaks are suppressed, and the parameter $\delta$ is reduced with increasing energy. Eventually it converges to the $[\pi,\pi]$ resonance peak. Thus the recently observed coexistence is interpreted in terms of bilayer interactions.Comment: 15 pages, Revtex, five figures are included, accepted for publication in Phys. Rev.