Water wave propagation and scattering over topographical bottoms

Here I present a general formulation of water wave propagation and scattering over topographical bottoms. A simple equation is found and is compared with existing theories. As an application, the theory is extended to the case of water waves in a column with many cylindrical steps

Theoretical analysis of the focusing of acoustic waves by two-dimensional sonic crystals

Motivated by a recent experiment on acoustic lenses, we perform numerical calculations based on a multiple scattering technique to investigate the focusing of acoustic waves with sonic crystals formed by rigid cylinders in air. The focusing effects for crystals of various shapes are examined. The dependance of the focusing length on the filling factor is also studied. It is observed that both the shape and filling factor play a crucial role in controlling the focusing. Furthermore, the robustness of the focusing against disorders is studied. The results show that the sensitivity of the focusing behavior depends on the strength of positional disorders. The theoretical results compare favorably with the experimental observations, reported by Cervera, et al. (Phys. Rev. Lett. 88, 023902 (2002)).Comment: 8 figure

Organic film thickness influence on the bias stress instability in Sexithiophene Field Effect Transistors

In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6) Field Effect Transistors (FETs) has been investigated. T6 FETs have been fabricated by vacuum depositing films with thickness from 10 nm to 130 nm on Si/SiO2 substrates. After the T6 film structural analysis by X-Ray diffraction and the FET electrical investigation focused on carrier mobility evaluation, bias stress instability parameters have been estimated and discussed in the context of existing models. By increasing the film thickness, a clear correlation between the stress parameters and the structural properties of the organic layer has been highlighted. Conversely, the mobility values result almost thickness independent

B→KB\to K Transition Form Factor up to O(1/mb2){\cal O}(1/m^2_b) within the kTk_T Factorization Approach

In the paper, we apply the $k_T$ factorization approach to deal with the $B\to K$ transition form factor $F^{B\to K}_{+,0}(q^2)$ in the large recoil regions. The B-meson wave functions $\Psi_B$ and $\bar\Psi_B$ that include the three-particle Fock states' contributions are adopted to give a consistent PQCD analysis of the form factor up to ${\cal O} (1/m^2_b)$. It has been found that both the wave functions $\Psi_B$ and $\bar\Psi_B$ can give sizable contributions to the form factor and should be kept for a better understanding of the $B$ meson decays. Then the contributions from different twist structures of the kaon wavefunction are discussed, including the $SU_f(3)$-breaking effects. A sizable contribution from the twist-3 wave function $\Psi_p$ is found, whose model dependence is discussed by taking two group of parameters that are determined by different distribution amplitude moments obtained in the literature. It is also shown that $F^{B\to K}_{+,0}(0)=0.30\pm0.04$ and $[F^{B\to K}_{+,0}(0)/F^{B\to \pi}_{+,0}(0)]=1.13\pm0.02$, which are more reasonable and consistent with the light-cone sum rule results in the large recoil regions.Comment: 22 pages and 6 figure

Rugose coral diversifications and migrations in the devonian of Australasia

The occurence of approximately 100 rugose coral genera has been confirmed in the Devonian carbonate dominated successions of Australasia. Their temporal distribution shows that the largest faunal turnovers were in the Pragian and Givetian, with profound extinction events at or near the ends of the Emsian, Givetian and Frasnian. The evolutionary innovation and diversification of the Early Devonian rugose corals of eastern Australia are characterized by a high turnover rate in the late Lochkovian - Pragian and strong dynamism of radiation from late Pragian to medial Emsian, implying considerable dispersal to South China, central Asia and Europe. After a high intensity of origination in the Pragian, maximum diversity was reached in the Emsian. Phillipsastreids and endophyllids appeared late in the Pragian and became common in the Emsian; stringophyllids appeared in the Emsian. As elements of these families are recorded mainly from the Middle, or even Upper Devonian of other provinces of the Old World Realm, it appears that they may have originated in eastern Australia during the Early Devonian. Following a marked decrease in generic richness in the Eifelian, faunal diversity reached another high peak in the early mid-Givetian as a result of immigration of coral genera, probably from South China, central Asia, Europe and northwestern Canada in the Old World Realm

Cambrian and Ordovician stratigraphy and biostratigraphy of the Arafura Basin, offshore Northern Territory

Recovery of conodonts and other fossils from four petroleum exploration wells (Esso Tasman 1 and Torres 1; Petrofina Goulburn 1 and Arafura 1), drilled in the Goulburn Graben of the Arafura Basin off the northern coast of Australia, have extended the known distribution of both Ordovician and Cambrian sediments across part of the northern Australian continental margin. The Cambrian and Ordovician sediments in the Arafura Basin comprise the four formations of the Goulburn Group. The recovered fossils indicate that in the offshore, the Jigaimara Formation is most likely of middle to late Templetonian age, the Naningbura Dolomite is Furongian to early Tremadocian, the Milingimbi Formation is middle Tremadocian, and the Mooroongga Formation is of late Tremadocian to middle Floian age