Systematics of some beta-transitions

0⁺ excited states of even-even nuclei can arise in several ways. In order to throw some light on the mechanism of excitation of these states, the log (ft) values for beta-transitions to the 0⁺ excited state and the 0⁺ ground state of even-even nuclei have been compared. In this analysis both allowed and forbidden beta-transitions have been considered. This survey is similar to that of beta-transitions by M. Sakai. Results of the present analysis are presented and compared to that of Sakai.     

Spatiotemporal binary interaction and designer quasi-particle condensates

We introduce a new integrable model to investigate the dynamics of two component quasi-particle condensates with spatiotemporal interaction strengths. We derive the associated Lax pair of the coupled Gross-Pitaevskii （GP） equation and construct matter wave solitons, We show that the spatiotemporal binary interaction strengths not only facilitate the stabilization of the condensates, but also enables one to fabricate condensates with desirable densities, geometries, and properties, leading to the so-called ＂designer quasi-particle condensates＂.     

Rainbow Connection Number of Graph Power and Graph Products

Rainbow connection number, rc(G), of a connected graph G is the minimum number of colors needed to color its edges so that every pair of vertices is connected by at least one path in which no two edges are colored the same (note that the coloring need not be proper). In this paper we study the rainbow connection number with respect to three important graph product operations (namely the Cartesian product, the lexicographic product and the strong product) and the operation of taking the power of a graph. In this direction, we show that if G is a graph obtained by applying any of the operations mentioned above on non-trivial graphs, then rc(G) ≤ 2r(G) + c, where r(G) denotes the radius of G and \({c \in \{0, 1, 2\}}\) . In general the rainbow connection number of a bridgeless graph can be as high as the square of its radius [1]. This is an attempt to identify some graph classes which have rainbow connection number very close to the obvious lower bound of diameter (and thus the radius). The bounds reported are tight up to additive constants. The proofs are constructive and hence yield polynomial time \({(2 + \frac{2}{r(G)})}\) -factor approximation algorithms.     

A partial-propensity formulation of the stochastic simulation algorithm for chemical reaction networks with delays

Several real-world systems, such as gene expression networks in biological cells, contain coupled chemical reactions with a time delay between reaction initiation and completion. The non-Markovian kinetics of such reaction networks can be exactly simulated using the delay stochastic simulation algorithm (dSSA). The computational cost of dSSA scales with the total number of reactions in the network. We reduce this cost to scale at most with the smaller number of species by using the concept of partial reaction propensities. The resulting delay partial-propensity direct method (dPDM) is an exact dSSA formulation for well-stirred systems of coupled chemical reactions with delays. We detail dPDM and present a theoretical analysis of its computational cost. Furthermore, we demonstrate the implications of the theoretical cost analysis in two prototypical benchmark applications. The dPDM formulation is shown to be particularly efficient for strongly coupled reaction networks, where the number of reactions is much larger than the number of species.     

Study of Thin Polymeric Film Deposited by the PECVD Process for use at 193 nm

A plasma enhanced chemical vapor deposition (PECVD) reactor was used to deposit thin polymeric films with high absorption at 193 nm. The reactor is suitable to deposit uniform and pinhole free thin polymeric films with conformality over 95%. Conformal films with thickness as low as 200 Å have been deposited on silicon, glass, and quartz substrates, as well as silicon oxide, silicon nitrate, and aluminum films. Deposited films had variations in thickness of 3 to 5% over an area of 8 inches in diameter. Thin films deposited on silicon substrates under varying levels of RF power were scanned using the AFM technique. The measurements show increasing surface roughness of the scanned samples as the RF power increases.     

A 2‐Tyr‐1‐carboxylate Mononuclear Iron Center Forms the Active Site of a Paracoccus Dimethylformamidase

N,N‐dimethyl formamide (DMF) is an extensively used organic solvent but is also a potent pollutant. Certain bacterial species from genera such as Paracoccus, Pseudomonas, and Alcaligenes have evolved to use DMF as a sole carbon and nitrogen source for growth via degradation by a dimethylformamidase (DMFase). We show that DMFase from Paracoccus sp. strain DMF is a halophilic and thermostable enzyme comprising a multimeric complex of the α₂β₂ or (α₂β₂)₂ type. One of the three domains of the large subunit and the small subunit are hitherto undescribed protein folds of unknown evolutionary origin. The active site consists of a mononuclear iron coordinated by two Tyr side‐chain phenolates and one carboxylate from Glu. The Fe³⁺ ion in the active site catalyzes the hydrolytic cleavage of the amide bond in DMF. Kinetic characterization reveals that the enzyme shows cooperativity between subunits, and mutagenesis and structural data provide clues to the catalytic mechanism.     

Generic crack patterns in rubber‐modified polymers under biaxial stress states

The damage mechanisms in three different systems, namely, acrylonitrile‐butadiene‐styrene, methacrylate‐butadiene‐styrene modified poly(vinyl chloride), and styrene‐butadiene‐styrene have been investigated. The damage was analyzed over a range of biaxial stress states with confocal microscopy and scanning electron microscopy. The macroscopic yield followed a linear behavior for all the systems in an octahedral shear stress versus mean stress plot, whereas popular models for this class of materials predicted a nonlinear response. Over a certain range of biaxial stress states, a damage pattern generic to all the systems was observed. The damage pattern consisted of an array of cracks propagating perpendicular to the direction of the maximum tensile principal stress and arranged itself in a more or less periodic fashion. There was also self‐similarity in the patterns at various length scales. Similar patterns have also occurred in several other polymeric systems. The interaction in the ensemble of cracks created seems to lead to stress reduction at the crack tips, thereby limiting the crack sizes. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2248–2256, 2003     

A Brillouin study of the temperature-dependence of the acoustic modes across the insulator-metal transitions in V2O3 and Cr-doped V2O3

Brillouin scattering studies have been carried out on high-quality single crystals of undoped and 0.9% Cr-doped V₂O₃. The observed modes in both the samples at ∼12 and ∼60 GHz are associated with the surface Rayleigh wave (SRW) and bulk acoustic wave (BAW), respectively. In the undoped sample, the mode frequencies of the SRW and BAW modes decrease as the temperature is lowered from room temperature to the insulator-metal transition temperature (T_IM=T_N=∼130 K). Below the transition, the modes show hardening. In the doped sample, the SRW mode shows a similar temperature-dependence as the undoped one, but the BAW mode shows hardening from room temperature down to the lowest temperature (50 K). This is the first measurement of the sound velocity below T_IM in the V₂O₃ system. The softening of the SRW frequency from 330 K to T_IM can be qualitatively understood on the basis of the temperature-dependence of C₄₄, which, in turn, is related to the orbital fluctuations in the paramagnetic metallic phase. The hardening of the mode frequencies below T_IM suggests that C₄₄ must increase in the antiferromagnetic insulating phase, possibly due to the orbital ordering.