The effect of addition of sucrose and aeration to grape must on growth and metabolic activity of Saccharomyces cerevisiae

Supplementation of grape must with sucrose has an inhibitory effect on yeast growth, but increases the catabolic activity of yeast populations. It is best done after the initial phase of yeast growth (between days 2 and 4), simultaneously to a short period of aeration which stimulates yeast growth and rate of sugar utilisation

Chromosomal Location of Lectin Genes Indicates They Are Not the Basis of Rhizobium Strain Specificity Mutations Identified in Pea (Pisum sativum L.)

A lectin gene family is located on linkage group 7 in pea. The lectin genes are arranged as a cluster, with no recombination observed within the multigene family. A lectinlike cDNA clone, pEA207, and eight DNA fragments generated by random priming also were mapped in the region of the lectin genes. None of the known pea mutants altering Rhizobium leguminosarum strain specificity map to this region of the genome, and therefore their altered specificities appear not to be directly produced by mutations in the lectin gene

Non-nodulating Mutants of Pisum Sativum (L.) cv. Sparkle

Eleven pea mutants, displaying a greatly reduced number of root nodules or lacking such nodules completely, were obtained by screening the M2 progeny of mutagenized Pisum sativum cv. Sparkle. The mutant alleles conditioning the altered nodulation phenotypes were recessive to the wild-type alleles. Eight of the mutants possessed a normal growth habit except for the complete lack of nodules. Pairwise crosses among these mutants indicated that five distinct loci had been affected. The remaining three mutants formed few nodules and also had altered root or shoot growth habit. Each of these plejotropic mutants was coded by a distinct gene. The eight genes identified are designated sym7, sym8, sym9, sym10, sym11, sym15, sym16, and sym17, signifying their involvement in the pea/Rhizobium symbiosis. The locations of most of these sym genes were determined by classical linkage mapping. The loci were distributed on at least five of the seven chromosome

On the Early History of Current Algebra

The history of Current Algebra is reviewed up to the appearance of the Adler-Weisberger sum rule. Particular emphasis is given to the role current algebra played for the historical struggle in strong interaction physics of elementary particles between the S-matrix approach based on dispersion relations and field theory. The question whether there are fundamental particles or all hadrons are bound or resonant states of one another played an important role in this struggle and is thus also regarded.Comment: 17 page

Assimilation of passive microwave AMSR-2 satellite observations in a snowpack evolution model over northeastern Canada

Over northeastern Canada, the amount of water stored in a snowpack, estimated by its snow water equivalent (SWE) amount, is a key variable for hydrological applications. The limited number of weather stations driving snowpack models over large and remote northern areas generates great uncertainty in SWE evolution. A data assimilation (DA) scheme was developed to improve SWE estimates by updating meteorological forcing data and snowpack states with passive microwave (PMW) satellite observations and without using any surface-based data. In this DA experiment, a particle filter with a Sequential Importance Resampling algorithm (SIR) was applied and an inflation technique of the observation error matrix was developed to avoid ensemble degeneracy. Advanced Microwave Scanning Radiometer 2 (AMSR-2) brightness temperature (TB) observations were assimilated into a chain of models composed of the Crocus multilayer snowpack model and radiative transfer models. The microwave snow emission model (Dense Media Radiative Transfer – Multi-Layer model, DMRT-ML), the vegetation transmissivity model (ω-τopt), and atmospheric and soil radiative transfer models were calibrated to simulate the contributions from the snowpack, the vegetation, and the soil, respectively, at the top of the atmosphere. DA experiments were performed for 12 stations where daily continuous SWE measurements were acquired over 4 winters (2012–2016). Best SWE estimates are obtained with the assimilation of the TBs at 11, 19, and 37&thinsp;GHz in vertical polarizations. The overall SWE bias is reduced by 68&thinsp;% compared to the original SWE simulations, from 23.7&thinsp;kg&thinsp;m−2 without assimilation to 7.5&thinsp;kg&thinsp;m−2 with the assimilation of the three frequencies. The overall SWE relative percentage of error (RPE) is 14.1&thinsp;% (19&thinsp;% without assimilation) for sites with a fraction of forest cover below 75&thinsp;%, which is in the range of accuracy needed for hydrological applications. This research opens the way for global applications to improve SWE estimates over large and remote areas, even when vegetation contributions are up to 50&thinsp;% of the PMW signal.</p

Actions of the braid group, and new algebraic proofs of results of Dehornoy and Larue

This article surveys many standard results about the braid group with emphasis on simplifying the usual algebraic proofs. We use van der Waerden's trick to illuminate the Artin-Magnus proof of the classic presentation of the algebraic mapping-class group of a punctured disc. We give a simple, new proof of the Dehornoy-Larue braid-group trichotomy, and, hence, recover the Dehornoy right-ordering of the braid group. We then turn to the Birman-Hilden theorem concerning braid-group actions on free products of cyclic groups, and the consequences derived by Perron-Vannier, and the connections with the Wada representations. We recall the very simple Crisp-Paris proof of the Birman-Hilden theorem that uses the Larue-Shpilrain technique. Studying ends of free groups permits a deeper understanding of the braid group; this gives us a generalization of the Birman-Hilden theorem. Studying Jordan curves in the punctured disc permits a still deeper understanding of the braid group; this gave Larue, in his PhD thesis, correspondingly deeper results, and, in an appendix, we recall the essence of Larue's thesis, giving simpler combinatorial proofs.Comment: 51`pages, 13 figure

Structural and hemodynamic comparison of anatomical and synthetic cerebral capillary networks

A computational method is presented for generating synthetic, random 3D capillary networks which match the topological, geometrical and functional properties of the cerebral microcirculation. These networks, which can be generated in volumes larger than can currently be extracted by high-resolution imaging, can then be coupled to lower-resolution data sets of whole-brain vasculature to model blood flow and mass transport, and to validate equivalent continuum/hybrid models. Another motivation is to reveal the dominant structural features of cerebral capillary networks, which can then be tuned to model different brain regions or pathological states such as Alzheimer’s disease. Previous works [1, 2] lacked physiological basis, and although resulting networks conformed to expected global morphometric properties, were not subjected to thorough topological or functional analysis. In contrast, our approach is based on the physiological assumption that the maximum separation of tissue cells from the nearest capillary is limited by the diffusion distance of oxygen [3]. Previously, synthetic, space-filling 2D networks were constructed by placing one point randomly in each cell of an n × n grid; from this set of points, Voronoi diagrams were extracted with the edges producing a 2D network with mainly three capillaries per vertex, a characteristic feature of cerebral capillary networks. Here, we extend this approach to 3D. In 3D, Voronoi diagrams produce polyhedrons with many capillaries per vertex. To derive a network with only bifurcations, clusters of vertices were systematically merged and capillaries then removed randomly. Geometrical metrics such as the mean/S.D. of lengths and edge/length/vertex densities were compared to those of capillary regions extracted from mouse cerebral anatomical data sets [5, 6]. Capillary loops were studied to measure the interconnected network topology, while the distribution of extravascular distances allowed comparison of the spatial arrangement of capillaries. Finally, hemodynamic properties were captured through the network permeability. Overall, synthetic networks showed excellent agreement with the anatomical data. This work was supported by ERC BrainMicroFlow GA615102. We acknowledge D. Kleinfeld, P. Tsai and P. Blinder for kindly sharing their anatomical data with us