Testing the scale-dependent hemispherical asymmetry with the 21-cm power spectrum from the epoch of reionization

Hemispherical power asymmetry has emerged as a new challenge to cosmology in early Universe. While the cosmic microwave background (CMB) measurements indicated the asymmetry amplitude A ≃ 0.07 at the CMB scale $k_{\rm CMB}\simeq 0.0045\, {\rm Mpc}^{-1}$, the high-redshift quasar observations found no significant deviation from statistical isotropy. This conflict can be reconciled in some scale-dependent asymmetry models. We put forwards a new parametrization of scale-dependent asymmetric power spectrum, inspired by a multispeed inflation model. The 21-cm power spectrum from the epoch of reionization can be used to constrain the scale-dependent hemispherical asymmetry. We demonstrate that an optimum, multifrequency observation by the Square Kilometre Array (SKA) Phase 2 can impose a constraint on the amplitude of the power asymmetry anomaly at the level of ΔA ≃ 0.2 at $0.056 \lesssim k_{\rm 21cm} \lesssim 0.15 \, {\rm Mpc}^{-1}$. This limit may be further improved by an order of magnitude as ΔA ≃ 0.01 with a cosmic variance limited experiment such as the Omniscope.

Observed Hurricane Wind Speed Asymmetries and Relationships to Motion and Environmental Shear

Wavenumber-1 wind speed asymmetries in 35 hurricanes are quantified in terms of their amplitude and phase, based on aircraft observations from 128 individual flights between 1998 and 2011. The impacts of motion and 850–200-mb environmental vertical shear are examined separately to estimate the resulting asymmetric structures at the sea surface and standard 700-mb reconnaissance flight level. The surface asymmetry amplitude is on average around 50% smaller than found at flight level, and while the asymmetry amplitude grows in proportion to storm translation speed at the flight level, no significant growth at the surface is observed, contrary to conventional assumption. However, a significant upwind storm-motion-relative phase rotation is found at the surface as translation speed increases, while the flight-level phase remains fairly constant. After removing the estimated impact of storm motion on the asymmetry, a significant residual shear direction-relative asymmetry is found, particularly at the surface, and, on average, is located downshear to the left of shear. Furthermore, the shear-relative phase has a significant downwind rotation as shear magnitude increases, such that the maximum rotates from the downshear to left-of-shear azimuthal location. By stratifying observations according to shear-relative motion, this general pattern of a left-of-shear residual wind speed maximum is found regardless of the orientation between the storm’s heading and shear direction. These results are quite consistent with recent observational studies relating western Pacific typhoon wind asymmetries to environmental shear. Finally, changes in wind asymmetry over a 5-day period during Hurricane Earl (2010) are analyzed to understand the combined impacts of motion and the evolving shear.

FIRST MEASUREMENT OF THE CP-VIOLATING ASYMMETRIES WITH BABAR

We report on a preliminary measurement of time-dependent CP-violating asymmetries in [Formula: see text] and [Formula: see text] decays recorded by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. The data sample consisted of 9.0 fb-1 collected at the ϒ(4S) resonance and 0.8 fb-1 off-resonance. One of the pair of neutral B mesons produced at the ϒ(4S) was fully reconstructed, while the flavor of the other neutral B meson was tegged at the time of its decay. The value of the asymmetry amplitude, sin 2β, was determined from a maximum likelihood fit to the time distribution of 120 tegged candidates to be sin 2β=0.12±0.37( stat. )± 0.09( syst. ) (preliminary).

Pressure Field and Main-Stream Gas Ingestion in a Rotor-Stator Disk Cavity

The time-average and unsteady static pressure fields, and the velocity field were measured in a rotor-stator disk cavity and its main-stream gas path. Ingestion of main gas into the disk cavity was also measured. Some CFD simulations were performed. The time-average static pressure was circumferentially periodic (following the vane pitch) in the main-stream gas path and circumferentially uniform in the cavity. The unsteady pressure in the stationary frame of reference was periodic, following the passing of rotor blades, both in the main gas path and in the disk cavity. In the main gas path, the circumferential asymmetry amplitude of the time-average static pressure and the pressure unsteadiness amplitude were of the same order of magnitude. Steady CFD simulations were unable to predict ingestion in the cases where ingestion was detected by tracer gas measurement. It appears that simulations will need to be unsteady as well as three-dimensional to be able to predict ingestion correctly.