N N bar,Delta bar N, Delta N bar excitation for the pion propagator in nuclear matter

The particle-hole and Delta -hole excitations are well-known elementary excitation modes for the pion propagator in nuclear matter. But, the excitation also involves antiparticles, namely, nucleon-antinucleon, anti-Delta-nucleon and Delta-antinucleon excitations. These are important for high-energy momentum as well, and have not been studied before, to our knowledge. In this paper, we give both the formulas and the numerical calculations for the real and the imaginary parts of these excitations.Comment: Latex, 3 eps file

Consistent off-shell πNN\pi N N vertex and nucleon self-energy

We present a consistent calculation of half-off-shell form factors in the pion-nucleon vertex and the nucleon self-energy. Numerical results are presented. Near the on-shell point the pion-nucleon vertex is dominated by the pseudovector coupling, while at large nucleon invariant masses we find a sizable pseudoscalar admixture.Comment: 23 pages, 7 figures, REVTeX, submitted to Phys. Rev. C, replaced with corrected versio

UV continuum emission and diagnostics of hydrogen-containing non-equilibrium plasmas

For the first time the emission of the radiative dissociation continuum of the hydrogen molecule ($a^{3}\Sigma_{g}^{+} \to b^{3}\Sigma_{u}^{+}$ electronic transition) is proposed to be used as a source of information for the spectroscopic diagnostics of non-equilibrium plasmas. The detailed analysis of excitation-deactivation kinetics, rate constants of various collisional and radiative transitions and fitting procedures made it possible to develop two new methods of diagnostics of: (1) the ground $X^{1}\Sigma_{g}^{+}$ state vibrational temperature $T_{\text{vib}}$ from the relative intensity distribution, and (2) the rate of electron impact dissociation (d[\mbox{H_{2}}]/dt)_{\text{diss}} from the absolute intensity of the continuum. A known method of determination of $T_{\text{vib}}$ from relative intensities of Fulcher-$\alpha$ bands was seriously corrected and simplified due to the revision of $d \to a$ transition probabilities and cross sections of $d \gets X$ electron impact excitation. General considerations are illustrated with examples of experiments in pure hydrogen capillary-arc and H$_{2}$+Ar microwave discharges.Comment: REVTeX, 25 pages + 12 figures + 9 tables. Phys. Rev. E, eprint replaced because of resubmission to journal after referee's 2nd repor

Modes of activation of organometallic iridium complexes for catalytic water and C–H oxidation

Sodium periodate (NaIO4) is added to Cp*Ir-III (Cp* = C5Me5-) or (cod)Ir-I (cod = cyclooctadiene) complexes, which are water and C-H oxidation catalyst precursors, and the resulting aqueous reaction is investigated from milliseconds to seconds using desorption electrospray ionization, electrosonic spray ionization, and cryogenic ion vibrational predissociation spectroscopy. Extensive oxidation of the Cp* ligand is observed, likely beginning with electrophilic C-H hydroxylation of a Cp* methyl group followed by nonselective pathways of further oxidative degradation. Evidence is presented that the supporting chelate ligand in Cp*Ir(chelate) precursors influences the course of oxidation and is neither eliminated from the coordination sphere nor oxidatively transformed. Isomeric products of initial Cp* oxidation are identified and structurally characterized by vibrational spectroscopy in conjunction with density functional theory (DFT) modeling. Less extensive but more rapid oxidation of the cod ligand is also observed in the (cod)Ir-I complexes. The observations are consistent with the proposed role of Cp* and cod as sacrificial placeholder ligands that are oxidatively removed from the precursor complexes under catalytic conditions.Chemistry, Inorganic & NuclearSCI(E)[email protected]; [email protected]

The hemispherical asymmetry from a scale-dependent inflationary bispectrum

If the primordial bispectrum is sufficiently large then the CMB hemispherical asymmetry may be explained by a large-scale mode of exceptional amplitude which perturbs the zeta two-point function. We extend previous calculations, which were restricted to one- or two-source scenarios, by providing a method to compute the response of the two-point function in any model yielding a 'local-like' bispectrum. In general, this shows that it is not the reduced bispectrum fNL which sources the amplitude and scale-dependence of the mode coupling but rather a combination of 'response functions'. We discuss why it is difficult to construct successful scenarios and enumerate the fine-tunings which seem to be required. Finally, we exhibit a concrete model which can be contrived to match the observational constraints and show that to a Planck-like experiment it would appear to have |fNL-local| ~ |fNL-equi| ~ |fNL-ortho| ~ 1. Therefore, contrary to previous analyses, we conclude that it is possible to generate the asymmetry while respecting observational constraints on the bispectrum and low-ell multipoles even without tuning our location on the long-wavelength mode

A CMB Gibbs sampler for localized secondary anisotropies

As well as primary fluctuations, CMB temperature maps contain a wealth of additional information in the form of secondary anisotropies. Secondary effects that can be identified with individual objects, such as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects due to galaxy clusters, are difficult to unambiguously disentangle from foreground contamination and the primary CMB however. We develop a Bayesian formalism for rigorously characterising anisotropies that are localised on the sky, taking the TSZ and KSZ effects as an example. Using a Gibbs sampling scheme, we are able to efficiently sample from the joint posterior distribution for a multi-component model of the sky with many thousands of correlated physical parameters. The posterior can then be exactly marginalised to estimate properties of the secondary anisotropies, fully taking into account degeneracies with the other signals in the CMB map. We show that this method is computationally tractable using a simple implementation based on the existing Commander component separation code, and also discuss how other types of secondary anisotropy can be accommodated within our framework

Determination of natural pyrethrins by liquid chromatography-electron ionisation-mass spectrometry.

Introduction – Pyrethrum extract is a mixture of six insecticidal compounds from the flower heads of Chrysanthemum cinerariaefolium L.. Since they only have low to moderate mammalian toxicity they can be used as natural insecticides in agriculture or to develop low cost and safe dermatological formulations. Because of the thermal instability of pyrethrins, analytical methods based on liquid chromatography (LC) are preferred over those based on gas chromatography (GC). A few applications using LC with mass spectrometry detection are presented in the literature. Current protocols for their characterisation by LC rely on the use of less sophisticated detectors such as UV detection. Objective – To develop the first liquid chromatography‐electron ionisation‐mass spectrometry (LC‐EI‐MS) method for pyrethrins detection and quantitation in pyrethrum extracts. Methodology – A commercial pyrethrum extract and various samples of flower heads from C. cinerariaefolium L. were investigated using reversed‐phase nano‐liquid chromatography coupled to direct electron ionisation‐mass spectrometry (nanoLCdirect EI‐MS). The eluted compounds were identified through searches of the US National Institute of Standards and Technology (NIST) library, exploiting the direct EI capability to produce high quality EI mass spectra. Results – The method demonstrated satisfactory sensitivity (limit of detection (LOD) range: 0.04–0.38 mg/g), linearity (R2 range: 0.9740–0.9983) and precision (RSD% range: 4–13%) for the quantitation of the natural pyrethrins in extracts from C. cinerariaefolium L. Conclusion – The nanoLC‐direct EI‐MS technique can be a useful tool for the detection of pyrethrins

Rissbeherrschung massiger Betonbauteile: Bauwerk, Werkstoff, Simulation

SIGLEAvailable from TIB Hannover: RA 1125(153) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman