Symmetric simple exclusion process with free boundaries

We consider the one dimensional symmetric simple exclusion process (SSEP) with additional births and deaths restricted to a subset of configurations where there is a leftmost hole and a rightmost particle. At a fixed rate birth of particles occur at the position of the leftmost hole and at the same rate, independently, the rightmost particle dies. We prove convergence to a hydrodynamic limit and discuss its relation with a free boundary problem.Comment: 29 pages, 4 figure

Transient jets in the symbiotic prototype Z Andromedae

We present development of the collimated bipolar jets from the symbiotic prototype Z And that appeared and disappeared during its 2006 outburst. In 2006 July Z And reached its historical maximum at U ~ 8.0. During this period, rapid photometric variations with Dm ~ 0.06 mag on the timescale of hours developed. Simultaneously, high-velocity satellite components appeared on both sides of the H-alpha and H-beta emission line profiles. They were launched asymmetrically with the red/blue velocity ratio of 1.2 - 1.3. From about mid-August they became symmetric. Their spectral properties indicated ejection of bipolar jets collimated within an average opening angle of 6.1 degrees. We estimated average outflow rate via jets to dM(jet)/dt ~ 2xE10-6(R(jet)/1AU)**(1/2) M(Sun)/year, during their August - September maximum, which corresponds to the emitting mass in jets, M(jet, emitting) ~ 6xE-10(Rjet)/1AU)^{3/2} M(Sun). During their lifetime, the jets released the total mass of M(jet, total) approx 7.4x1E-7 M(Sun). Evolution in the rapid photometric variability and asymmetric ejection of jets around the optical maximum can be explained by a disruption of the inner parts of the disk caused by radiation-induced warping of the disk.Comment: 31 pages, 9 figures, 2 tables, accepted for Ap

Chemical characterization and economic evaluation of the coal fly ash pre-washing and carbonation process

In the present laboratory-scale study, the combination of washing and carbonation processes was examined to evaluate the feasibility to reduce the environmental impact of coal power plants. Three different washing solutions (tap, distilled and sea water) were used to pre-treat coal fly ash and the corresponding effect on direct gas-solid carbonation and final metal leaching was evaluated. Finally, a preliminary economic evaluation of the process was performed. In terms of captured CO2, the results have shown that significant amounts can be captured, although, as expected, the leaching of soluble salts in water such as Ca and Mg reduce the CO2 uptake. In terms of heavy metal's leaching, the application of pre-washing and carbonation treatment significantly affected the metal immobilization on the final residue. The pre-washing with sea water allowed to reach a sensible improvement since only selenium, chlorides and sulphates resulted outside the range for disposing of the carbonated residue in landfill for non-hazardous waste

Transcriptional regulation of ascorbic acid during fruit ripening in pepper (Capsicum annuum) varieties with low and high antioxidants content

Research on plant antioxidants, such as ascorbic acid (AsA) and polyphenols, is of increasing interest in plant science because of the health benefits and preventive role in chronic diseases of these natural compounds. Pepper (Capiscum annuum L.) is a major dietary source of antioxidants, especially AsA. Although considerable advance has been made, our understanding of AsA biosynthesis and its regulation in higher plants is not yet exhaustive. For instance, while it is accepted that AsA content in cells is regulated at different levels (e.g., transcriptional and post-transcriptional), their relative prominence is not fully understood. In this work, we identified and studied two pepper varieties with low and high levels of AsA to shed light on the transcriptional mechanisms that can account for the observed phenotypes. We quantified AsA and polyphenols in leaves and during fruit maturation, and concurrently, we analyzed the transcription of 14 genes involved in AsA biosynthesis, degradation, and recycling. The differential transcriptional analysis indicated that the higher expression of genes involved in AsA accumulation is a likely explanation for the observed differences in fruits. This was also supported by the identification of gene-metabolite relations, which deserve further investigation. Our results provide new insights into AsA differential accumulation in pepper varieties and highlight the phenotypic diversity in local germplasm, a knowledge that may ultimately contribute to the increased level of health-related phytochemicals