Deep inelastic Compton scattering at theep collider HERA

Deep inelastic Compton scattering at HERA is investigated with the intention of determining the usefulness of this process in pinning down the photon and proton structure functions. We examine the contributions of the various _s and _s ² subprocesses that arise from the nonelementary structure of the photon atS _p =30000 GeV². An assessment is made of the sensitivity of this process to the various parton and photon structure functions presently available. In particular we study the possibility of directly measuring the gluon content of the proton and the photon as well as the quark fragmentation into a photon with this process. Theep laboratory frame helps to separate out the different contributions and in particular may allow a quantitative study of the box diagram term.     

A two primers random amplified polymorphic DNA procedure to obtain polymerase chain reaction fingerprints of bacterial species

Polymerase chain reation (PCR) fingerprints are used to characterize and recognize bacteria and are generally obtained using universal primers that generate an array of DNA amplicons, which can be separated by electrophoresis. Universal primers 8F and 1491 R have been used to amplify specifically 16S rDNA. We have used these primers at an annealing temperature of 50 degrees C. Agarose gel electrophoresis of PCR products revealed several bands. The band pattern of each bacterial species was different and the strains belonging to the same species shared an identical pattern. The patterns obtained did not show variations with plasmid DNA content or the growth stage of the bacteria. The peculiarity of the randomly amplified polymorphic DNA (RAPD) described in this work lies in the use of two large primers (proximately 20 nt) to obtain the pattern, since normally a only smaller primer is used, and in the new application for the primers used to amplify 16S rDNA. This new procedure, called two primers (TP)-RAPD fingerprinting, is thus rapid, sensitive, reliable, highly reproducible and suitable for experiments with a large number of microorganisms, and can be applied to bacterial taxonomy, ecological studies and for the detection of new bacterial species.     

Deep inelastic Compton process and large QCD corrections

The reactions \(\bar vD \to \mu ^ + n\pi ^ - (p_s )\) and \(\bar vD \to \mu ^ + p\pi (n_s )\) have been studied at antineutrino energies varying from 5 to 200 GeV. The cross sections for these reactions were determined from 545 and 300 selected events for each channel respectively. The first reaction was used for the study of the decay properties of the Δ resonance that dominates this channel. The experimental results have been compared with the theoretical predictions of Rein and Sehgal [9] and of Fogli and Nardulli [10]. Using the first model we obtained for the axial form factor parameterM _a =1.01±0.05 GeV/c². With this value the model is in agreement with the experimentaldσ/dQ ² distributions forQ ²>0.25 GeV² and with the distributions of the invariant hadronic massW. The isospin structure of the one-pion production has been investigated and compared with the results of other experiments.     

Crystal structure of 7-cyano-6,7-dimethyl-1-phenyl-1,3,6,7-tetrahydro-2,1-benzoxaphospole 1-oxide

The crystals (C₁₆H₁₈NO₂P,M _r=287.30) are orthorhombic, space group Pbca witha=8.200(2),b=14.857(2), andc=24.396(5)Å,V=2972.1 ų,Z=8,D _x=1.284 mg m^–3,(MoK)=0.71069 Å,=1.90 cm^–1,F(000)=216,T=295K. FinalR=0.044 for 1673 observed reflections collected on a diffractometer. Structure solved by direct methods.Cis-junction and double bond in the six-membered ring cause its almost ideal sofa conformation. The two neighboring methyl groups are cis, and cyano substituent is in an equatorial position. There is a shortintramolecular H(o-phenyl)O(endocyclic) contact of 2.53(3)Å and the phenyl ring is in a less favorable rotational orientation due to molecular packing.     

Continuity of operators commuting with translations for compact groups

In this note we show for certain Frechet spacesF(G) of functions (distributions) on a compact groupG that if every translation invariant linear functional onF(G) is continuous then every linear operatorT:F(G)F(G) commuting with translations is continuous. This solves partially a problem in [7] ofG. H. Meisters and improves the result [5] ofC. J. Lester. An application for compact groups which do not have the mean zero weak containment property follows by the result [10] ofG. A. Willis.     

Application of horizontal staircase electrophoresis in agarose minigels to the random intergenic spacer analysis of clinical samples

The random intergenic spacer analysis is a recently developed technique for the study of microbial populations. The bacterial intergenic spacer (ITS) is located between 16S rRNA and 23S rRNA genes and presents different length and sequence among bacterial species. Therefore, the amplicons can be separated by electrophoresis commonly performed at low voltage during several hours. Although this technique is especially useful for unculturable microorganisms, it has not been applied before to clinical sample analysis. As these samples have a limited number of bacterial species, the size of the gels may be reduced to facilitate their handling and to reduce the running time. To obtain maximum separation among the ITS bands, we analysed in this work different electrophoretical conditions including staircase electrophoresis, a technique based on the application of several voltage steps. The results obtained showed a different behaviour of the electrical resistance during the performance of submarine horizontal and vertical staircase electrophoresis. In the first case the resistance decreased during most of the running time whereas in the second case it increased. Here, we show that the performance of horizontal staircase electrophoresis reduces the running time more than 80% with respect to conventional electrophoresis at low voltages. This procedure was applied to the separation of ITS bands from bacterial DNA present in a tissue from a vocal cord biopsy. The sequencing of these bands allowed their identification. This new procedure may be very useful in the rapid diagnosis of bacteria present in human, animal and plant tissues.     

Plane structures in thermal runaway

We consider the problem

1. u _t=u _xx+e ^u whenx ∈ ?,t > 0,
2. u(x, 0) =u ₀(x) whenx ∈ ?,

whereu ₀(x) is continuous, nonnegative and bounded. Equation (1) appears as a limit case in the analysis of combustion of a one-dimensional solid fuel. It is known that solutions of (1), (2) blow-up in a finite timeT, a phenomenon often referred to as thermal runaway. In this paper we prove the existence of blow-up profiles which are flatter than those previously observed. We also derive the asymptotic profile ofu(x, T) near its blow-up points, which are shown to be isolated.     

A comparison of structure and stability between the group 11 halide tetramers M4X4 (M = Cu, Ag, or Au; X = F, Cl, Br, or I) and the group 11 chloride and bromide phosphanes (XMPH3)4

The tetramers of the group 11 (I) halides, M(4)X(4) (M = Cu, Ag, or Au; X = F, Cl, Br, or I), and corresponding group 11 (I) phosphanes, chloride and bromide (XMPH(3))(4) (X = Cl or Br), are investigated by the density functional theory. All coinage metal(I) halide tetramers adopt squarelike ring structures with an out-of-plane distorted (butterfly) D(2d) symmetry. These structures are much lower in energy than the more compact cubelike T(d) arrangements, which maximize dipole-dipole interactions and more closely resemble the solid-state structures of the copper and silver halides. Phosphine coordination completely changes the structures of these M(4)X(4) clusters. The copper(I) and silver(I) phosphane chloride and bromide tetramers adopt a heterocubane structure, slightly preferred over a step (ladder-type)-cluster structure well-known in the coordination chemistry of such compounds. In stark contrast, gold(I) phosphane chloride and bromide tetramers prefer assemblies of linear XAuPH(3) units with direct gold-gold contacts, resulting in a square planar, centered trigonal planar, or tetrahedral gold core.