Study of the decay mechanism for B+ to p pbar K+ and B+ to p pbar pi+

We study the characteristics of the low mass ppbar enhancements near threshold in the three-body decays B+ to p pbar K+ and B+ to p pbar pi+. We observe that the proton polar angle distributions in the ppbar helicity frame in the two decays have the opposite polarity, and measure the forward-backward asymmetries as a function of the ppbar mass for the p pbar K+ mode. We also search for the intermediate two-body decays, B+ to pbar Delta++ and B+ to p Delta0bar, and set upper limits on their branching fractions. These results are obtained from a 414 fb^{-1} data sample that contains 449 times 10^6 BBbar events collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.Comment: 15 pages, 5 figures (14 figure files), revisions to Phys. Lett.

Quantification of hanging wall effects on ground motion. Some insigths from the 1999 Chi-Chi earthquake.

International audienceAccelerometric records of the Chi-Chi earthquake from sites on the hanging wall exhibit larger acceleration than those from the footwall. Based on ground accelerations recorded at 79 near-field stations (10 hanging-wall stations and 69 footwall stations, respectively) and precise mapping of fault-rupture traces, the hanging-wall/footwall effects of the Chi-Chi earthquake have been fully studied. We show that the hanging-wall effects cannot be simply accounted for by a proper choice of distance metric. The closest distance to the rupture plane (Drup) is then selected to develop an empirical ground-motion model by using the data collected during the mainshock of the Chi-Chi earthquake that struck Taiwan. With the exception of some sites immediately next to the rupture traces (Drup ≤ 5 km), the acceleration residuals between this empirical model and the recorded data at the footwall stations are close to zero for stations in the distance range from 5 to 50 km. On the other hand, the average acceleration amplification on the hanging wall is equal to the natural logarithmic values of 0.64 ± 0.4 for all hanging-wall sites within 20 km of Drup. The hanging-wall/footwall effects have also been evaluated for several response spectral periods. It is observed that both the horizontal and vertical components of spectral acceleration are apparently amplified for sites on the hanging wall at a distance from 5 to 20 km for spectral periods 0.02 to 0.5 sec, whereas the vertical component has less amplification than the horizontal in all the spectral periods considered. The horizontal component of spectral acceleration at the hanging-wall sites also shows a larger value for the long-period motion, relative to the footwall, for periods larger than 1.0 sec. The hanging-wall effects are relatively constant, at low frequencies, as the distance extends to about 20 km. This observation cannot be explained by the simplified empirical model. Rather, it suggests that waves trapped in the hanging-wall wedge may have been involved

IMAGE SHARING WITH STEGANOGRAPHY AND CHEATER IDENTIFICATION

In 2004, Lin and Tsai applied the concept of a threshold secret sharing scheme and the method of parity check to design a secret image sharing and authentication mechanisms. However, cheaters can easily counterfeit a fake stego-image in Lin and Tsai's scheme. In order to overcome this problem, Yang et al. proposed an improved scheme to prevent the users from making a fake stego-image. While Yang et als scheme embeds just one pixel of secret image into each block, it doesnt meet the property of high-capacity. Furthermore, the modular number in their scheme is 28 rather than a prime number. Thus, the secret image cannot be successfully reconstructed from t stego-images in their scheme. In this paper, we will propose an improved scheme which can not only embed t pixels of secret image into each block but also the reconstructed secret image can be established. Moreover, we apply the Data Signature Algorithm (DSA) for cheater identification

Characterization and biocompatibility of chitosan nanocomposites

Chitosan nanocomposites were prepared from chitosan and gold nanoparticles (AuNPs) or silver nanoparticles (AgNPs) of similar to 5 nm size. Transmission electron microscopy (TEM) showed the NPs in chitosan did not aggregate until higher concentrations (120-240 ppm). Atomic force microscopy (AFM) demonstrated that the nanocrystalline domains on chitosan surface were more evident upon addition of AuNPs (60 ppm) or AgNPs (120 ppm). Both nanocomposites showed greater elastic modulus, higher glass transition temperature (T(g)) and better cell proliferation than the pristine chitosan. Additionally, chitosan-Ag nanocomposites had antibacterial ability against Staphylococcus aureus. The potential of chitosan-Au nanocomposites as hemostatic wound dressings was evaluated in animal (rat) studies. Chitosan-Au was found to promote the repair of skin wound and hemostasis of severed hepatic portal vein. This study indicated that a small amount of NPs could induce significant changes in the physicochemical properties of chitosan, which may increase its biocompatibility and potential in wound management. (C) 2011 Elsevier B.V. All rights reserved

Polyhydroxyalkanoate biosynthesis in Bacillus cereus SPV under varied limiting conditions and an insight into the biosynthetic genes involved

Aims: A new strain of Bacillus, Bacillus cereus SPV, was found to be capable of using a wide range of carbon sources for the production of polyhydroxyalkanoates (PHAs) (Valappil et al. 2007b). Limiting nutrient in the culture conditions is crucial for PHA production. In this study, B. cereus SPV was grown in different culture conditions with limitation of potassium, nitrogen, sulphur and phosphorous to establish the impact of nutritional limitation on PHA production. Methods and Results: The PHA yields obtained were found to be 13·4, 38, 13·15 and 33·33% dcw for potassium, nitrogen, sulphur and phosphorus limitations, respectively. Gas chromatography–mass spectrometry analysis of the isolated polymers showed the presence of P(3HB) under nitrogen, sulphur and phosphate-limiting conditions and P(3HB-3HV) copolymer under potassium limiting conditions. This ability of B. cereus SPV to accumulate different PHA monomers from structurally unrelated carbon sources led to an interest in the molecular analysis of PHA biosynthesis in this organism. To achieve this, PCR was used to identify the polyhydroxyalkanoate biosynthetic genes in B. cereus SPV. Conclusion: Sequence analysis of the PCR products from B. cereus SPV revealed the sequence of the putative biosynthetic genes, and possible regions involved in substrate binding