Mean field analysis of Williams-Bjerknes type growth

We investigate a class of stochastic growth models involving competition between two phases in which one of the phases has a competitive advantage. The equilibrium populations of the competing phases are calculated using a mean field analysis. Regression probabilities for the extinction of the advantaged phase are calculated in a leading order approximation. The results of the calculations are in good agreement with simulations carried out on a square lattice with periodic boundaries. The class of models are variants of the Williams- Bjerknes model for the growth of tumours in the basal layer of an epithelium. In the limit in which only one of the phases is unstable the class of models reduces to the well known variants of the Eden model.Comment: 21 pages, Latex2e, Elsevier style, 5 figure

Nitrogen cycling in root associated soils at bolting, flowering and seed pod filling across eight diverse Brassica napus (canola) genotypes

Non-Peer ReviewedNitrogen (N) mineralization and nitrification can be used predict the amount of N that is available to crops. Brassica napus L. (canola) production is N intensive; therefore, to improve and sustain yields, a better understanding of N cycling patterns for fertilization application is needed. The objective of this study is to examine N cycling after urea fertilization at the three major canola growth stages: bolting, flowering and seed pod filling; and how N cycling may differ between diverse canola lines grown in different soil types. Eight diverse B. napus lines were grown on Dark Brown Chernozemic soil and Black Chernozemic soil in Saskatchewan, Canada. Root-associated soils were collected from each line at bolting, flowering and seed pod filling, and this soil was analyzed for potential nitrification and mineralization, as well as soil nitrate and ammonium content. We predict that potential nitrification will be higher during the bolting and flowering stages of canola growth because the urea fertilizer that was applied to the field would have been converted to nitrate-N, which is plant available. We predict that potential mineralization will be higher during flowering and seed pod filling, because the demand for N to make protein-rich seeds is high enough to deplete much of the inorganic fertilizer N. We also predict that both nitrate-N and ammonium-N will decrease over the growing season, with significant differences between the canola lines and the soil environments. Mixed effect analyses and ANOVA will be used to analyze N cycling in the soil in relation to soil type differences, canola line differences, and growth stage differences. By characterizing soil N processes, this research will advance efforts to understand and improve N uptake for B. napus lines

Dynamics of root-associated fungal community of canola genotypes in Saskatchewan soils

Non-Peer Reviewe

Photon and Z induced heavy charged lepton pair production at a hadron supercollider

We investigate the pair production of charged heavy leptons via photon-induced processes at the proposed CERN Large Hadron Collider (LHC). Using effective photon and Z approximations, rates are given for $L^+L^-$ production due to $\gamma \gamma$ fusion and $Z \gamma$ fusion for the cases of inelastic, elastic and semi-elastic $pp$ collisions. These are compared with the corresponding rates for production via the gluon fusion and Drell-Yan mechanisms. Various $\gamma \gamma$ and $Z \gamma$ differential luminosities for $pp$ collisions are also presented.Comment: 22 pages, RevTex 3.0, 6 uuencoded and compressed postscript figures included. Reference to one paper changed from the original preprint number to the published version. Everything else unchange

Responding to the Event Deluge

We present the VOEventNet infrastructure for large-scale rapid follow-up of astronomical events, including selection, annotation, machine intelligence, and coordination of observations. The VOEvent standard is central to this vision, with distributed and replicated services rather than centralized facilities. We also describe some of the event brokers, services, and software that are connected to the network. These technologies will become more important in the coming years, with new event streams from Gaia, LOFAR, LIGO, LSST, and many others.Comment: Submitted to Proceedings of SPIE Observatory Operations, Amsterdam, 2012 July 2-

Chemical composition, free-radical-scavenging and insecticidal activities of the aerial parts of Stachys byzantina

Stachys byzantina K. Koch. is an Iranian endemic species of the genus Stachys L., which comprises about 300 species, and is one of the largest genera of the family Lamiaceae. A combination of solid phase extraction (SPE) and high pressure liquid chromatography (HPLC) of the methanolic extract of the aerial parts of S. byzantina afforded three phenylethanoids, 2'-O-arabinosyl verbascoside (1), verbascoside (2), aeschynanthoside C (3) and three flavones apigenin 7-O-glucoside (4), apigenin 7-O-(6-p-coumaroyl)-glucoside (5) and apigenin (6). The structures of these compounds were determined by spectroscopic methods. Free-radical-scavenging and insecticidal properties of the crude extracts, the fractions and the isolated compounds were assessed.

Regulating in vivo calcification of alginate microbeads

Alginate calcification has been previously reported clinically and during animal implantation; however no study has investigated the mechanism, extensively characterized the mineral, or evaluated multiple methods to regulate or eliminate mineralization. In the present study, alginate calcification was first studied in vitro: calcium-crosslinked alginate beads sequestered surrounding phosphate while forming traces of hydroxyapatite. Calcification in vivo was then examined in nude mice using alginate microbeads with and without adipose stem cells (ASCs). Variables included the delivery method, site of delivery, sex of the animal, time in vivo, crosslinking solution, and method of storage prior to delivery. Calciumcrosslinked alginate microbeads mineralized when injected subcutaneously or implanted intramuscularly after 1e6 months. More extensive analysis with histology, microCT, FTIR, XRD, and EDS showed calcium phosphate deposits throughout the microbeads with surface mineralization that closely matched hydroxyapatite found in bone. Incorporating 25 mM bisphosphonate reduced alginate calcification whereas using barium chloride eliminated mineralization. Buffering the crosslinking solution with HEPES at pH 7.3 while washing and storing samples in basal media prior to implantation also eliminated calcification in vivo. This study shows that alginate processing prior to implantation can significantly influence bulk hydroxyapatite formation and presents a method to regulate alginate calcificationAlginate calcification has been previously reported clinically and during animal implantation; however no study has investigated the mechanism, extensively characterized the mineral, or evaluated multiple methods to regulate or eliminate mineralization. In the present study, alginate calcification was first studied in vitro: calcium-crosslinked alginate beads sequestered surrounding phosphate while forming traces of hydroxyapatite. Calcification in vivo was then examined in nude mice using alginate microbeads with and without adipose stem cells (ASCs). Variables included the delivery method, site of delivery, sex of the animal, time in vivo, crosslinking solution, and method of storage prior to delivery. Calciumcrosslinked alginate microbeads mineralized when injected subcutaneously or implanted intramuscularly after 1e6 months. More extensive analysis with histology, microCT, FTIR, XRD, and EDS showed calcium phosphate deposits throughout the microbeads with surface mineralization that closely matched hydroxyapatite found in bone. Incorporating 25 mM bisphosphonate reduced alginate calcification whereas using barium chloride eliminated mineralization. Buffering the crosslinking solution with HEPES at pH 7.3 while washing and storing samples in basal media prior to implantation also eliminated calcification in vivo. This study shows that alginate processing prior to implantation can significantly influence bulk hydroxyapatite formation and presents a method to regulate alginate calcificatio

The resummation of inter-jet energy flow for gaps-between-jets processes at HERA

We calculate resummed perturbative predictions for gaps-between-jets processes and compare to HERA data. Our calculation of this non-global observable needs to include the effects of primary gluon emission (global logarithms) and secondary gluon emission (non-global logarithms) to be correct at the leading logarithm (LL) level. We include primary emission by calculating anomalous dimension matrices for the geometry of the specific event definitions and estimate the effect of non-global logarithms in the large $N_c$ limit. The resulting predictions for energy flow observables are consistent with experimental data.Comment: 31 pages, 4 figures, 2 table

Fibulin-1 Is Increased in Asthma – A Novel Mediator of Airway Remodeling?

Background: The extracellular matrix is a dynamic and complex network of macromolecules responsible for maintaining and influencing cellular functions of the airway. The role of fibronectin, an extracellular matrix protein, is well documented in asthma. However, the expression and function of fibulin-1, a secreted glycoprotein which interacts with fibronectin, has not been reported. Fibulin-1 is widely expressed in basement membranes in many organs including the lung. There are four isoforms in humans (A-D) of which fibulin-1C and 1D predominate. The objective of this study was to study the expression of fibulin-1 in volunteers with and without asthma, and to examine its function in vitro. Methodology/Principal Findings: We used immunohistochemistry and dot-blots to examine fibulin-1 levels in bronchial biopsies, bronchoalveolar lavage fluid and serum. Real-time PCR for fibulin-1C and 1D, and ELISA and western blotting for fibulin-1 were used to study the levels in airway smooth muscle cells. The function of fibulin-1C was determined by assessing its role, using an antisense oligonucleotide, in cell proliferation, migration and wound healing. A murine model of airway hyperresponsiveness (AHR) was used to explore the biological significance of fibulin-1. Levels of fibulin-1 were significantly increased in the serum and bronchoalveolar lavage fluid of 21 asthmatics compared with 11 healthy volunteers. In addition fibulin-1 was increased in asthma derived airway smooth muscle cells and fibulin-1C contributed to the enhanced proliferation and wound repair in these cells. These features were reversed when fibulin-1C was suppressed using an antisense oligomer. In a mouse model of AHR, treatment with an AO inhibited the development of AHR to methacholine. Conclusions: Our data collectively suggest fibulin-1C may be worthy of further investigation as a target for airway remodeling in asthma