Conformal Symmetry and Pion Form Factor: Soft and Hard Contributions

We discuss a constraint of conformal symmetry in the analysis of the pion form factor. The usual power-law behavior of the form factor obtained in the perturbative QCD analysis can also be attained by taking negligible quark masses in the nonperturbative quark model analysis, confirming the recent AdS/CFT correspondence. We analyze the transition from soft to hard contributions in the pion form factor considering a momentum-dependent dynamical quark mass from a nonnegligible constituent quark mass at low momentum region to a negligible current quark mass at high momentum region. We find a correlation between the shape of nonperturbative quark distribution amplitude and the amount of soft and hard contributions to the pion form factor.Comment: 7 pages, 6 figures, extensively revised, to appear in Phys. Rev.

Effect of alum (top-dressed and mixed) with rice hulls on pH and ammonia emissions from poultry houses

The use of aluminum sulfate [alum; Al2(SO3)4·14H2O] as top dressing to poultry litter has been proven in reducing ammonia (NH3) volatilization under both laboratory and field tests; however, there has been no information of alum application in mixing methods from poultry litter or rice hulls. The aim of the experiment was to evaluate the effects of alum top dressed or mixed with rice hulls as litter management methods on pH and NH3 emissions. A total of 180 broiler chickens were randomly allocated to 12 pens to a density of 0.07 m2/bird for 5 weeks, creating 4 replicates of 3 experimental treatments with 15 birds per experimental unit as a completely randomized design. The treatments included an untreated control, 100 g of alum (top dressing) and 100 g of alum (mixed)/kg of rice hull. In addition, alum treatment was usually applied by top dressing onto the rice hulls or fully mixed with the rice hulls. During the experimental period, pH and NH3 emissions were significantly reduced by the two different methods of alum amendments (P < 0.05) in the litter over time compared with the controls except for NH3 emissions at 1 through 3 weeks. However, no significant differences (P > 0.05) in pH and NH3 emission were observed between the two different methods with alum for 5 weeks. The reduction in NH3 emission from 100 g of alum top-dressed and 100 g of alum fully mixed with kg of rice hull at 5 weeks was 50 and 51%, respectively. In summary, these results indicate that “mixing” methods of alum as well as top dressing would serve as a suitable method for decreasing NH3 emission, which resulted in lower pH.Key words: Alum, top dressing, mixing, pH, ammonia

Ku-band system design study and TDRSS interface analysis

The capabilities of the Shuttle/TDRSS link simulation program (LinCsim) were expanded to account for radio frequency interference (RFI) effects on the Shuttle S-band links, the channel models were updated to reflect the RFI related hardware changes, the ESTL hardware modeling of the TDRS communication payload was reviewed and evaluated, in LinCsim the Shuttle/TDRSS signal acquisition was modeled, LinCsim was upgraded, and possible Shuttle on-orbit navigation techniques was evaluated

Poincare Invariant Algebra From Instant to Light-Front Quantization

We present the Poincare algebra interpolating between instant and light-front time quantizations. The angular momentum operators satisfying SU(2) algebra are constructed in an arbitrary interpolation angle and shown to be identical to the ordinary angular momentum and Leutwyler-Stern angular momentum in the instant and light-front quantization limits, respectively. The exchange of the dynamical role between the transverse angular mometum and the boost operators is manifest in our newly constructed algebra.Comment: 21 pages, 3 figures, 1 tabl

Effect of surface roughness on rate-dependent slip in simple fluids

Molecular dynamics simulations are used to investigate the influence of molecular-scale surface roughness on the slip behavior in thin liquid films. The slip length increases almost linearly with the shear rate for atomically smooth rigid walls and incommensurate structures of the liquid/solid interface. The thermal fluctuations of the wall atoms lead to an effective surface roughness, which makes the slip length weakly dependent on the shear rate. With increasing the elastic stiffness of the wall, the surface roughness smoothes out and the strong rate dependence is restored again. Both periodically and randomly corrugated rigid surfaces reduce the slip length and its shear rate dependence.Comment: 15 pages, 5 figures; submitted to J. Chem. Phy

Continuity of generalized parton distributions for the pion virtual Compton scattering

We discuss a consistent treatment of the light-front gauge-boson and meson wave functions in the analyses of the generalized parton distributions(GPDs) and the scattering amplitudes in deeply virtual Compton scattering(DVCS) for the pion. The continuity of the GPDs at the crossover, where the longitudinal momentum fraction of the probed quark is same with the skewedness parameter, and the finiteness of the DVCS amplitude are ensured if the same light-front radial wave function as that of the meson bound state wave function is used for the gauge boson bound state arising from the pair-creation(or nonvalence) diagram. The frame-independence of our model calculation is also guaranteed by the constraint from the sum rule between the GPDs and the form factors.Comment: 14 pages, 9 figures, we (1) changed the title, (2) added references, (3) discussed the GPD value at the crossover in Sec. III, version to appear in Phys. Rev.