Turing Instability in a Boundary-fed System

The formation of localized structures in the chlorine dioxide-idodine-malonic acid (CDIMA) reaction-diffusion system is investigated numerically using a realistic model of this system. We analyze the one-dimensional patterns formed along the gradients imposed by boundary feeds, and study their linear stability to symmetry-breaking perturbations (Turing instability) in the plane transverse to these gradients. We establish that an often-invoked simple local linear analysis which neglects longitudinal diffusion is inappropriate for predicting the linear stability of these patterns. Using a fully nonuniform analysis, we investigate the structure of the patterns formed along the gradients and their stability to transverse Turing pattern formation as a function of the values of two control parameters: the malonic acid feed concentration and the size of the reactor in the dimension along the gradients. The results from this investigation are compared with existing experiments.Comment: 41 pages, 18 figures, to be published in Physical Review

FLIGHT OF THE EUROPEAN CORN BORER (OSTRINIA NUBILALIS HBN.) AS FOLLOWED BY LIGHT- AND PHEROMONE TRAPS IN VÁRDA AND BALATONMAGYARÓD 2002

The investigations were made in 2002 in the outskirts of two settlements: Balatonmagyaród (Zala county) and Várda (Somogy county). In the corn fields Jermy’s light- and Arco-Pheron MZ pheromone traps were placed in order to follow up the course of flight. From the material collected the corn borer specimens were isolated, then separated by sex. The generation number of the populations appearing on the respective areas, and the characteristics of the flight were determined. The meteorological data of the areas obtained from Keszthely and Kaposvár for the period concerned were compared woth the data of flight. In that way the effect of the different meteorological elements on the flight and on the trend of the female ratio could be established. The results showed the presence of two-generation corn borer populations in both places. In Balatonmagyaród the first- while in Várda the second generation proved larger. The meteorological elements significally influenced the possibility of trapping in the case of both sexes. As for the female sex ratio close correlations were found with the minimum (P=100%; r=0.297)-, maximum (P=99.9%; r=0.267)-, average (P=100%; r=0.308) temperature and precipitation (P=98.2%; r=0.187) data. Considerable asynchrony was observed between the data obtained with the two prognostic means that we ascribed to the unreliability of the pheromone trap

Pressure-induced change of the pairing symmetry in superconducting CeCu2Si2

Low-temperature (T) heat-capacity measurements under hydrostatic pressure of up to p=2.1 GPa have been performed on single-crystalline CeCu2Si2. A broad superconducting (SC) region exists in the T-p phase diagram. In the low-pressure region antiferromagnetic spin fluctuations and in the high-pressure region valence fluctuations had previously been proposed to mediate Cooper pairing. We could identify these two distinct SC regions. We found different thermodynamic properties of the SC phase in both regions, supporting the proposal that different mechanisms might be implied in the formation of superconductivity.Comment: 4 pages, 5 figure

Managing Risk on the Final Frontier

The National Aeronautics and Space Administration (NASA). Exploration Systems Mission Directorate (ESMD) has combined the Continuous Risk Management (CRM) discipline with innovative knowledge management (KM) practices to more effectively enable the accomplishment of work. CRM enables proactive problem identification and problem solving in the complex world of rocket science. while KM is used to improve this process

Nonlinearities and Pomeron Nonfactorizability in Conventional Diffraction

Alternatives for describing the nonlinear behavior of the first diffraction cone in differential $pp$ and $\bar pp$ elastic cross-section are investigated. High quality fits to the data are presented. We show that the presence in the Pomeron amplitude of two terms with different $t$ dependences is strongly suggested by the data, hinting at a non-factorizable Pomeron even in the field of purely hadronic reactions. The available data, however, do no allow to choose among a nonlinearity in the residues or in the Pomeron trajectory or in both. In all cases, we find an effective slope of the trajectory larger than the one currently used. A nonlinear trajectory with the fitted parameters is used for predicting the mass and the width of the 2$^{++}$ glueball. An excellent agreement is found with the X(1900) candidate from the WA91 experiment.Comment: Plain TeX, 24 pages, 6 eps figures, to be published in Nuovo Ciment

Spin Effects in Two Quark System and Mixed States

Based on the numeric solution of a system of coupled channels for vector mesons ($S$- and $D$-waves mixing) and for tensor mesons ($P$- and $F$-waves mixing) mass spectrum and wave functions of a family of vector mesons $q\bar{q}$ in triplet states are obtained. The calculations are performed using a well known Cornell potential with a mixed Lorentz-structure of the confinement term. The spin-dependent part of the potential is taken from the Breit-Fermi approach. The effect of singular terms of potential is considered in the framework of the perturbation theory and by a configuration interaction approach (CIA), modified for a system of coupled equations. It is shown that even a small contribution of the $D$-wave to be very important at the calculation of certain characteristics of the meson states.Comment: 12 pages, LaTe

The invasive colonial ascidian Didemnum vexillum on Georges Bank - Ecological effects and genetic identification

Since the discovery of the invasive colonial tunicate Didemnum vexillum Kott, 2002 on Georges Bank in 2002, research has focused on investigating the spread of the tunicate invasion, evaluating its potential impact on the benthic community, identifying it to species level, and determining its region of origin. The percent cover of Didemnum vexillum, measured from bottom photographs, ranges from 0-100% in individual photos and between 0-79% when averaged within photo transects. Individual photos represent an area of the seabed measuring ~ 0.39 m2 while photo transects range from ~ 700-1000 meters in length. Hydroids are the second most abundant epifaunal taxon. The macrofauna identified in bottom photo analysis comprises 21 different taxa, of which burrowing and non-burrowing anemones are the most numerous. Our detailed analysis of bottom photographs suggests that Didemnum vexillum is able to out-compete other epifaunal and macrofaunal taxa. An Analysis of Similarity (ANOSIM) test on macrofauna abundance data collected with a Naturalist dredge from 1994 to 2006, indicates that Didemnum vexillum has had a significant impact on the species composition of the benthic community. The abundance of two polychaete species, Nereis zonata Malmgren, 1867 and Harmothoe extenuata Grube, 1840, increased significantly in infested areas compared with uninfested areas, according to two-way Analysis of Variance (ANOVA). We found four distinct nucleotide sequences of the 18s rDNA gene among 17 samples of Didemnum species, three from Georges Bank and one from New Zealand. Two of the Georges Bank sequences were identified as Didemnum albidum Verrill, 1871, a species native to the northeast United States. The third sequence represents the invasive Didemnum vexillum from Georges Bank, and the fourth sequence an undescribed species from New Zealand (not D. vexillum)