366 research outputs found
Supersymmetry Partial Breaking and Tadpole Anomaly
We consider the extension of the effective
supersymmetric model of ; and study the
explicit relationship between partial breaking of supersymmetry
constraint and D3 brane tadpole anomaly of type IIB string on Calabi-Yau
threefolds in presence of H and H fluxes. We also comment on
supersymmetry breaking in the particular Maxwell
theory; and study its interpretation in connection with the tadpole anomaly
with extra localized flux sources.Comment: LaTex 37 page
Development and validation of a method for the analysis of halophenols and haloanisoles in cork bark macerates by stir bar sorptive extraction heart-cutting two-dimensional gas chromatography negative chemical ionization mass spectrometry
A method has been developed for the quantitative determination in cork bark macerates of 7halophenols and 5haloanisoles with demonstrated or suspected contribution to the cork taint off-flavour. Macerates were extracted with stirbar (20 mm polydimethylsiloxane-coated) sorptive extraction under optimized conditions (pH 3.5, 20% NaCl and 60 min). The bars were analysed byautomated thermal desorption, heart-cutting two-dimensional gas chromatography and negative chemical ionization-mass spectrometry. Matrix effects were compensated for by a âmatrix matchedâ calibration curve. Limits of detection were in the range 0.03-0.24 ng L-1, below the corresponding odor thresholds. Linearity (0.983 = R2 = 0.998), intra- and inter-day precision (5.4-14.3%) and accuracy (89â126%) were satisfactory. The analysis of 48 natural cork bark samples affected/not-affected bya cryptogamic disease (yellow spot) revealed compositional differences in 2, 4, 6-trichloroanisole (2, 4, 6-TCA), 2, 4, 6-trichlorophenol (2, 4, 6-TCP) and also in 2, 6-dibromophenol, 2, 3, 4- and 2, 4, 5-TCP, 2, 3, 4-TCA and 2, 3, 4, 6-tetrachlorophenol (2, 3, 4, 6-TeCP). In addition, the contents of 2, 4, 6-TCP and 2, 4, 6-TCA, and 2, 3, 4, 6-TeCP and some TCPs presented strong linear correlations
Reduction of the model noise in non-linear reconstruction via an efficient calculation of the incident field: application to a 434 MHz Scanner
Microwave tomography has been drastically boosted by the development of efficient reconstruction algorithms based on an iterative solution of the corresponding non-linear inverse problem. The accuracy of the electric field radiated by the antennas of a microwave scanner, inside the target area, has been shown to play a significant role on the overall image quality. Taking into account the antenna environment is of prime importance, especially when operating at low frequency. For instance, the wall of a 60 cm diameter whole-body microwave scanner cannot be neglected at 434 MHz, even when using the immersion technique consisting of putting the target in water. Indeed, at such a frequency, the attenuation introduced by water is not sufficient to avoid multiple reflections on the scanner boundary walls. Consequently, the method of calculating the incident field constitutes a key factor in iteratively solving non-linear inverse problems. The selected technique must accommodate high accuracy while maintaining acceptable calculation complexity. In this paper, three distinct techniques are analysed. They are based on the use of i) free-space and ii) non free-space Green's function, and iii) a FDTD approach. All these techniques have been firstly investigated for their 2D version, being used in 2D reconstruction algorithms. However, the scattered field data are collected in a 3D scanner. For assessing the validity of the previous 2D techniques, their results have been compared to both experimentally and 3D-FDTD results.Peer ReviewedPostprint (published version
The Pomeron and Odderon in elastic, inelastic and total cross sections at the LHC
A simple model for elastic diffractive hadron scattering, reproducing the
dip-bump structure is used to analyze PP and scattering. The main
emphasis is on the delicate and non-trivial dynamics in the dip-bump region,
near t=-1 GeV. The simplicity of the model and the expected smallness of
the absorption corrections enables one the control of various contributions to
the scattering amplitude, in particular the interplay between the C-even and
C-odd components of the amplitude, as well as their relative contribution,
changing with s and t. The role of the non-linearity of the Regge trajectories
is scrutinized. The ratio of the real to imaginary parts of the forward
amplitude, the ratio of elastic to total cross sections and the inelastic cross
section are calculated. Predictions for the LHC energy region, where most of
the exiting models will be either confirmed or ruled out, are presented.Comment: 16 pages, 13 figures. Small correction. To be published in the
International Journal of Modern Physics
Nonlinear dynamics of soft fermion excitations in hot QCD plasma III: Soft-quark bremsstrahlung and energy losses
In general line with our early works [Yu.A. Markov, M.A. Markova, Nucl. Phys.
A770 (2006) 162; 784 (2007) 443] within the framework of a semiclassical
approximation the general theory of calculation of effective currents and
sources generating bremsstrahlung of an arbitrary number of soft quarks and
soft gluons at collision of a high-energy color-charged particle with thermal
partons in a hot quark-gluon plasma, is developed. For the case of one- and
two-scattering thermal partons with radiation of one or two soft excitations,
the effective currents and sources are calculated in an explicit form. In the
model case of `frozen' medium, approximate expressions for energy losses
induced by the most simple processes of bremsstrahlung of soft quark and soft
gluon, are derived. On the basis of a conception of the mutual cancellation of
singularities in the sum of so-called `diagonal' and `off-diagonal'
contributions to the energy losses, an effective method of determining color
factors in scattering probabilities, containing the initial values of Grassmann
color charges, is suggested. The dynamical equations for Grassmann color
charges of hard particle used by us early are proved to be insufficient for
investigation of the higher radiative processes. It is shown that for correct
description of these processes the given equations should be supplemented
successively with the higher-order terms in powers of the soft fermionic field.Comment: 93 pages, 20 figure
Diffractive Contribution to the Elasticity and the Nucleonic Flux in the Atmosphere
We calculate the average elasticity considering non-diffractive and single
diffractive interactions and perform an analysis of the cosmic-ray flux by
means of an analytical solution for the nucleonic diffusion equation. We show
that the diffractive contribution is important for the adequate description of
the nucleonic and hadronic fluxes in the atmosphere.Comment: 10 pages, latex, 2 figures (uuencoded PostScript
Pectin methyl esterases and rhamnogalacturonan hydrolases: weapons for successful Monilinia laxa infection in stone fruit?
The secretion of cell wallâdegrading enzymes is one of the mechanisms used by necrotrophic fungi to colonize host tissues. However, information about virulence factors of Monilinia spp., the causal agents of brown rot in stone fruit, is scarce. Plant cell walls have three main components that are broken down by fungal enzymes: cellulose, hemicellulose and pectin. In order to identify Monilinia laxa candidate proteins involved in pectin hydrolysis, two in vitro approaches were conducted: (i) phenotypic and ecophysiological characterization of growth of the pathogen at different pHs, in glucoseâ and pectinâcontaining solid media for 7 days' incubation; and (ii) expression analysis of genes encoding M. laxa pectin methyl esterases (MlPMEs) and rhamnogalacturonan hydrolases (MlRGâHYDs) after incubation for 0.5, 2, 6, 24 and 48 h in glucoseâ and pectinâcontaining liquid media. Phenotypic tests showed the role of carbon source on M. laxa growth rate and aggressiveness, and indicated that pectinases were greatly affected by pH. Gene expression analyses uncovered differences among members of each family of pectinases and between the two families, defining sets of genes expressed at earlier (0.5â6 h) and later (48 h) phases. Notably, the upâ or downâregulation of these target genes was carbon sourceâdependent. Finally, an in vivo study confirmed the synergistic and complementary role that these genes play in the M. laxaâstone fruit pathosystem. Based on these results, it is hypothesized that MlPME2, MlRGâHYD1 and MlRGâHYD2 may be potential virulence factors of M. laxa in the process from infection to colonization.info:eu-repo/semantics/acceptedVersio
Statistical Assessment of Shapes and Magnetic Field Orientations in Molecular Clouds through Polarization Observations
We present a novel statistical analysis aimed at deriving the intrinsic
shapes and magnetic field orientations of molecular clouds using dust emission
and polarization observations by the Hertz polarimeter. Our observables are the
aspect ratio of the projected plane-of-the-sky cloud image, and the angle
between the mean direction of the plane-of-the-sky component of the magnetic
field and the short axis of the cloud image. To overcome projection effects due
to the unknown orientation of the line-of-sight, we combine observations from
24 clouds, assuming that line-of-sight orientations are random and all are
equally probable. Through a weighted least-squares analysis, we find that the
best-fit intrinsic cloud shape describing our sample is an oblate disk with
only small degrees of triaxiality. The best-fit intrinsic magnetic field
orientation is close to the direction of the shortest cloud axis, with small
(~24 deg) deviations toward the long/middle cloud axes. However, due to the
small number of observed clouds, the power of our analysis to reject
alternative configurations is limited.Comment: 14 pages, 8 figures, accepted for publication in MNRA
Massless Thirring model in canonical quantization scheme
It is shown that the exact solvability of the massless Thirring model in the
canonical quantization scheme originates from the intrinsic linearizability of
its Heisenberg equations in the method of dynamical mappings. The corresponding
role of inequivalent representations of free massless Dirac field is
elucidated.Comment: 10 page
Fluxes of atmospheric muons underwater depending on the small-x gluon density
The prompt muon contribution to the deep-sea atmospheric muon flux can serve
as a tool for probing into the small-x feature of the gluon density inside of a
nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt
muon flux underwater is calculated taking into consideration predictions of
recent charm production models in which the small-x behaviour of the gluon
distribution is probed. We discuss the possibility of distinguishing the PQCD
models of the charm production differing in the small-x exponent of the gluon
distribution, in measurements of the muon flux at energies 10-100 TeV with
neutrino telescopes.Comment: 9 pages, 4 eps figures, uses iopart.st
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