Density matrix renormalization group for the Berezinskii-Kosterlitz-Thouless transition of the 19-vertex model

We embody the density matrix renormalization group (DMRG) method for the 19-vertex model on a square lattice in order to investigate the Berezinskii-Kosterlitz-Thouless transition. Elements of the transfer matrix of the 19-vertex model are classified in terms of the total value of arrows in one layer of the square lattice. By using this classification, we succeed to reduce enormously the dimension of the matrix which has to be diagonalized in the DMRG method. We apply our method to the 19-vertex model with the interaction $K=1.0866$ and obtain $c=1.006(1)$ for the conformal anomaly. PACS. 05.90.+m, 02.70.-cComment: RevTeX style, 20 pages, 12 figure

In vivo mapping of nucleosomes using psoralen-DNA crosslinking and primer extension

By the use of psoralen crosslinking and primer extension, a method was developed which allows the analysis of chromatin structure in vivo. Using a yeast minichromosome, >9 nucleosomes were mapped with a resolution of at least ±30 b

In vitro transcription of the Bacillus subtilis phage ø29 DNA by Bacillus subtilis and Escherichia coli RNA polymerases

The Escherichia coli RNA polymerase bound to phage ø29 DNA has been visualized by electron microscopy. Thirteen specific binding sites have been observed at 1.7,2.6,5.5,10.4,13.7,25.2,25.7,26.3,33.5,59.5,69.2,91.7 and 99.6 DNA length units and they have been named A1,A1I,A1II,A1III,A1IV,A2,A2I,A3,A4,B1,B1I,C1 and C2, respectively. The binding sites A1,A2,A3,B1,C1 and C2 coincide with those found with Bacillus subtills RNA polymerase. The transcription of phage ø29 DNA with B. subtilis or E. coli RNA polymerases has been studied. With the B. subtilis RNA polymerase eight transcripts were found, starting at positions corresponding to the binding sites A1, A1III, A2,A3,B1I,B2 and C2, respectively. With the E. coli RNA polymerase the same transcripts were found and a new one starting at position corresponding to the A4 binding site. The RNAs starting at binding sites A1,A1III,A2,B1I, B2,C1 and C2 are transcribed from right to left, as expected for early RNA. The RNAs which initiate at positions A3 arid A4 are transcribed from left to right and probably correspond to late RNAs.Peer reviewe

Chromatin structure and methylation of rat rRNA genes studied by formaldehyde fixation and psoralen cross-linking

By using formaldehyde cross-linking of histones to DNA and gel retardation assays we show that formaldehyde fixation, similar to previously established psoralen photocross-linking, discriminates between nucleosome-packed (inactive) and nucleosome-free (active) fractions of ribosomal RNA genes. By both cross-linking techniques we were able to purify fragments from agarose gels, corresponding to coding, enhancer and promoter sequences of rRNA genes, which were further investigated with respect to DNA methylation. This approach allows us to analyse independently and in detail methylation patterns of active and inactive rRNA gene copies by the combination of HpaII and MspI restriction enzymes. We found CpG methylation mainly present in enhancer and promoter regions of inactive rRNA gene copies. The methylation of one single HpaII site, located in the promoter region, showed particularly strong correlation with the transcriptional activit

Effect of Biological and Chemical Ripening Agents on the Nutritional and Metal Composition of Banana (Musa spp)

The use of potentially toxic ripening agents is common in developing countries. Four ripening agents namely calcium carbide, potash, African mango and jathropha curcas leaf were used and compared with a control with no ripening agent. Result showed that RB1 and RB2 were the first to ripen at 3days with RB5 at 6th day. Protein content reduced in the ripened samples in the order of 4.12>3.68>3.04>2.52>1.99>1.77%. Protein value was lowest when calcium carbide was used. Fat ash and fiber contents range between 0.28-1.72, 0.75-2.75and 0.50-1.75% respectively. The moisture content increased from 65.50 to 74.0%, while carbohydrate content range is 17.49-29.29%. Pb, Cu, Zn and Mn values of 0.22, 0.87, 1.96 and 0.67ppm was highest in calcium carbide ripened banana and lowest in the control 0.09, 0.26, 0.37 and 0.19 ppm.Keywords: Banana; ripening; ripening agents; postharvest losses; metal contaminatio

Spontaneous generation of spin-orbit coupling in magnetic dipolar Fermi gases

The stability of an unpolarized two-component dipolar Fermi gas is studied within mean-field theory. Besides the known instability towards spontaneous magnetization with Fermi sphere deformation, another instability towards spontaneous formation of a spin-orbit coupled phase with a Rashba-like spin texture is found. A phase diagram is presented and consequences are briefly discussed

Excited states nonlinear integral equations for an integrable anisotropic spin 1 chain

We propose a set of nonlinear integral equations to describe on the excited states of an integrable the spin 1 chain with anisotropy. The scaling dimensions, evaluated numerically in previous studies, are recovered analytically by using the equations. This result may be relevant to the study on the supersymmetric sine-Gordon model.Comment: 15 pages, 2 Figures, typos correcte

Polyhedral Oligomeric Silsesquioxane Based Catalyst for the Efficient Synthesis of Cyclic Carbonates

In this work, the synthesis of a novel imidazolium-based polyhedral oligomeric silsesquioxane (POSS-mim-Cl) material is presented. The new nanometer-size organosilica based compound was employed for chemical fixation of CO2 into epoxide under homogeneous conditions. The target reaction was represented by the obtention of cyclic carbonates starting from epoxides and CO2. Particularly, styrene oxide was chosen as reference substrate. In addition, different parameters (solvent, temperature, pressure of CO2, and mass of the catalyst) were modified to find the best condition for CO2 conversion. The catalyst POSS-mim-Cl displayed good catalytic performances, the best results being obtained at 40 bar of CO2, 150\ub0C, with 110 mg of catalyst and using isopropanol as co-solvent. It is worth to mention that POSS-mim-Cl displayed better catalytic performance than the corresponding 1-butyl-3-methyl imidazolium chloride. As far as we know this study represents the first use of imidazolium-based POSS as catalysts for the chemical fixation of CO2

Monopole Oscillations and Dampings in Boson and Fermion Mixture in the Time-Dependent Gross-Pitaevskii and Vlasov Equations

We construct a dynamical model for the time evolution of the boson-fermion coexistence system. The dynamics of bosons and fermions are formulated with the time-dependent Gross-Pitaevsky equation and the Vlasov equation. We thus study the monopole oscillation in the bose-fermi mixture. We find that large damping exists for fermion oscillations in the mixed system even at zero temperature.Comment: 16 pages text and 12 figure

Finite-dimensional analogs of string s <-> t duality and pentagon equation

We put forward one of the forms of functional pentagon equation (FPE), known from the theory of integrable models, as an algebraic explanation to the phenomenon known in physics as st duality. We present two simple geometrical examples of FPE solutions, one of them yielding in a particular case the well-known Veneziano expression for 4-particle amplitude. Finally, we interpret our solutions of FPE in terms of relations in Lie groups.Comment: LaTeX, 12 pages, 6 eps figure