181 research outputs found
1HNMR SPECTROSCOPIC AND HISTOLOGICAL OBSERVATIONS OF ISCHEMIC SPINAL CORD DURING REPERFUSION
No full textStudy of Bs→l+l−γ decays in covariant quark model
No full textWe study the rare radiative leptonic decays Bs → ell^+ ell^- gamma (ell= e, μ, τ) within the Standard Model, considering both the structure-dependent amplitude and bremsstrahlung. In the framework of the covariant confined quark model developed by us, we calculate the form factors characterizing the Bs → γ transition in the full kinematical region of the dilepton momentum squared and discuss their behavior. We provide the analytic formula for the differential decay distribution and give predictions for the branching fractions in both cases: with and without long-distance contributions. Finally, we compare our results with those obtained in other approaches
Quantification of 1HNMR Blood serum lipoprotein spectra in stroke and in alzheimer's disease: a preliminary comparative study
No full text1H NMR Spectroscopy and Histological Observations of Ischemic Spinal Cord During Reperfusion
No full textObservations of Metabolic and Histological Alterations in the Rabbit Signal Cord Ischemia, 1H NMRS Study
No full textStudy of Charm Quark Fragmentation into Mesons with the H1 Detector at HERA II
No full textIn this work charm quark fragmentation into mesons
is investigated in deep-inelastic electron proton collisions. This
work is based on data collected in the years 2004 - 2007 by the H1
detector at HERA, corresponding to a total integrated luminosity of
354.1 pb^-1.
Three observables denoted z_jet, z_hem
and z_hem^(jet) are measured, each of them
meant to approximate the momentum fraction of the charm quark transferred
to the D^* meson. In case of z_jet the quark momentum
is estimated as the momentum of the D^* jet, for the two other
observables it is approximated by the momentum of an appropriately
chosen D^* hemisphere. The visible range is defined by the phase
space requirements on the DIS events: Q^2 > 5 GeV^2,
0.05 < y < 0.6 and by the cuts applied on the reconstructed D^* ±
particles: 1.5 GeV < p_T(D^*) < 15.0 GeV and
|\eta(D^*)|< 1.5. An additional constraint E_T(D^* jet)> 3.0 GeV
enters the phase space definition in case of z_jet and
z_hem^(jet), where a reconstructed jet containing
the D^* meson is required. Within this phase space the normalized
single differential cross sections are measured in bins of the three
observables. Two Monte Carlo models, RAPGAP and CASCADE, both interfaced
with the PYTHIA program for the Lund string fragmentation, are used
to make predictions of the respective cross sections for different
parametrizations (Peterson and Kartvelishvili) of the charm fragmentation
function. The difference in cross sections between data and Monte
Carlo model predictions for different values of the fragmentation
parameter is quantified by calculating values of X^2 in order
to extract optimal parameters for the Peterson and Kartvelishvili
parametrization. Using predictions from PYTHIA for e^+e^- annihilation
optimal parameters are extracted also from the published BELLE and
ALEPH data.
The obtained results show that the H1 data allow the determination
of the fragmentation parameters with a precision which is of interest.
The extracted parameters are however found to apparently depend on
the charm quark production energy: the z_hem -based results
are not consistent with those derived from z_jet and z_hem^(jet), and inconsistencies are also
observed when comparing to e^+e^- values. The results suggest
that existing models, including the investigated simple fragmentation
functions, are not adequate in describing charm fragmentation at different
production energies with the same set of fragmentation parameters
The oxidative rearrangement of furan-2-carboximidamides: preparation and properties of 2-acylaminofurans
No full textOxidation of furan-2-carboximidamides 8 by (dicarboxyiodo)benzenes gives N-1-acyl-N-1-(2-furyl)ureas 9 via rearrangement to a carbodiimide. Thermolysis of eleven ureas 9 gave the corresponding 2-acylaminofurans 10, which cannot be made from the free amines owing to their high instability. When oxidation of the corresponding benzo[b]furan derivatives 12 was investigated a new type of product was isolated, in addition to the expected ureas 14, and these were shown to be benzo[4,5]furo[2,3-d]pyrimidine derivatives 15. The mechanism of formation of these products must involve reaction of the carbodiimide intermediate with the amidine precursor and cyclisation of the resulting guanidine derivatives 19. The corresponding tetraphenylguanidine 21 was prepared and underwent thermal cyclisation but the quinazoline derivative formed 23 was shown to occur via an alternative cyclisation mechanism. The structures of cyclisation products 15 and 23 were confirmed by X-ray crystallography. N-(2-Furyl)acetamide 10a readily undergoes cycloaddition reactions with electron-deficient alkynes to give phenols after spontaneous ring opening. Observed regioselectivity is in agreement with the results of AM1 molecular orbital calculations. Reaction of the amide 10a with Lawesson's reagent gave the thioamide 26
The Observation of Free Radicals (FR) in Rabbit Spinal Cord Ischemia by Electron Spin Resonance Spectroscopy,method: comparative study with H magnetic resonance spectroscopy e Histology
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