Long-range correlation and multifractality in Bach's Inventions pitches

We show that it can be considered some of Bach pitches series as a stochastic process with scaling behavior. Using multifractal deterend fluctuation analysis (MF-DFA) method, frequency series of Bach pitches have been analyzed. In this view we find same second moment exponents (after double profiling) in ranges (1.7-1.8) in his works. Comparing MF-DFA results of original series to those for shuffled and surrogate series we can distinguish multifractality due to long-range correlations and a broad probability density function. Finally we determine the scaling exponents and singularity spectrum. We conclude fat tail has more effect in its multifractality nature than long-range correlations.Comment: 18 page, 6 figures, to appear in JSTA

The DNA-binding domain of the Chd1 chromatin-remodelling enzyme contains SANT and SLIDE domains

The ATP-dependent chromatin-remodelling enzyme Chd1 is a 168-kDa protein consisting of a double chromodomain, Snf2-related ATPase domain, and a C-terminal DNA-binding domain. Here, we show the DNA-binding domain is required for Saccharomyces cerevisiae Chd1 to bind and remodel nucleosomes. The crystal structure of this domain reveals the presence of structural homology to SANT and SLIDE domains previously identified in ISWI remodelling enzymes. The presence of these domains in ISWI and Chd1 chromatin-remodelling enzymes may provide a means of efficiently harnessing the action of the Snf2-related ATPase domain for the purpose of nucleosome spacing and provide an explanation for partial redundancy between these proteins. Site directed mutagenesis was used to identify residues important for DNA binding and generate a model describing the interaction of this domain with DNA. Through inclusion of Chd1 sequences in homology searches SLIDE domains were identified in CHD6–9 proteins. Point mutations to conserved amino acids within the human CHD7 SLIDE domain have been identified in patients with CHARGE syndrome

A new scenario for the Domerian-Toarcian transition

Pour tenter de mieux comprendre l’événement d’anoxie océanique globale au Toarcien inférieur, il convient de remonter aux changements environnementaux qui ont précédé cette phase paroxysmale. En effet, la comparaison des séquences sédimentaires et biostratigraphiques du passage Domérien-Toarcien entre la Téthys occidentale (Maroc, Espagne, Portugal) et l’Europe du Nord-Ouest (Causses, Allemagne, Angleterre) fait apparaître une importante lacune dans la région septentrionale. La faune d’Arieticeratinae (Emaciaticeras, Canavaria, Fontanelliceras) et d’Harpoceratinae (Lioceratoides, Neolioceratoides), accompagnée ensuite de Dactylioceras particuliers (groupe mirabile-polymorphum = sous-genre Eodactylites), fait presque totalement défaut en Europe du Nord-Ouest, alors qu’elle abonde dans les dernières alternances marno-calcaires, sans changement lithologique notable avec le Domérien des coupes téthysiennes. Cette faune est intercalée entre les derniers Pleuroceras et les Dactylioceras du groupe tenuicostatum. Ces derniers apparaissent dans les argiles succédant immédiatement au dernier banc calcaire à Dactylioceras mirabile au Portugal notamment. C’est là le diachronisme déjà reconnu entre les limites lithostratigraphique (disparition des bancs calcaires) et biostratigraphique (apparition du genre Dactylioceras) au passage Domérien-Toarcien. Cette observation peut s’intégrer dans un nouveau scénario paléo-océanographique prenant en compte à la fois la tendance régressive majeure du Domérien supérieur (conduisant à une lacune régionale importante), l’abondance de matière charbonneuse dans les premiers dépôts transgressifs du Toarcien et l’événement anoxique global subséquent. Dans la partie supérieure du Domérien, l’existence d’un fort volcanisme peut être déduite des données relatives aux variations des isotopes du strontium [McArthur et al., 2000]. A ce pic de strontium sont associées une faible anomalie négative du δ13 C à la limite Domérien-Toarcien et des valeurs particulièrement élevées du δ18 O [Morettini et Bartolini, 1999]. Nous pensons que cette activité volcanique débute par des émissions massives de SO2 induisant des pluies acides, un obscurcissement et un refroidissement. A cette phase de refroidissement correspond une augmentation de l’englacement des pôles et une régression responsable de la lacune majeure évoquée plus haut, particulièrement sensible dans les mers épicontinentales. Bien que les preuves directes d’une glaciation fini-domérienne fassent actuellement défaut [Hallam, 2001], le glacio-eustatisme nous semble le seul mécanisme permettant d’expliquer une oscillation marine importante mais de courte durée [Brandt, 1986 ; Dewey et Pitman, 1998]. En effet, le cycle régression-transgression s’étale sur environ deux zones d’ammonites, la lacune sédimentaire en elle-même recouvrant essentiellement les sous-zones à Elisa et Mirabile. Ce premier épisode serait suivi, dans la zone à Tenuicostatum, par une importante perturbation du cycle du carbone responsable d’un effet de serre. Le réchauffement, provoquerait alors la transgression bien connue du Toarcien inférieur, cachetant le hiatus sédimentaire dans la province nord-ouest européenne. L’intervalle de temps correspondant à cette lacune aurait permis à la végétation de coloniser les immenses surfaces nouvellement émergées. C’est le lessivage et l’oxydation de la matière organo-humique et bactérienne accumulée pendant cette période, associée à une élévation de la température, qui aurait enclenché le mécanisme d’anoxie lors du paroxysme de la transgression

Determination of the b quark mass at the M_Z scale with the DELPHI detector at LEP

An experimental study of the normalized three-jet rate of b quark events with respect to light quarks events (light= \ell \equiv u,d,s) has been performed using the CAMBRIDGE and DURHAM jet algorithms. The data used were collected by the DELPHI experiment at LEP on the Z peak from 1994 to 2000. The results are found to agree with theoretical predictions treating mass corrections at next-to-leading order. Measurements of the b quark mass have also been performed for both the b pole mass: M_b and the b running mass: m_b(M_Z). Data are found to be better described when using the running mass. The measurement yields: m_b(M_Z) = 2.85 +/- 0.18 (stat) +/- 0.13 (exp) +/- 0.19 (had) +/- 0.12 (theo) GeV/c^2 for the CAMBRIDGE algorithm. This result is the most precise measurement of the b mass derived from a high energy process. When compared to other b mass determinations by experiments at lower energy scales, this value agrees with the prediction of Quantum Chromodynamics for the energy evolution of the running mass. The mass measurement is equivalent to a test of the flavour independence of the strong coupling constant with an accuracy of 7 permil.Comment: 24 pages, 10 figures, Accepted by Eur. Phys. J.

Study of Leading Hadrons in Gluon and Quark Fragmentation

The study of quark jets in e+e- reactions at LEP has demonstrated that the hadronisation process is reproduced well by the Lund string model. However, our understanding of gluon fragmentation is less complete. In this study enriched quark and gluon jet samples of different purities are selected in three-jet events from hadronic decays of the Z collected by the DELPHI experiment in the LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are defined by requiring a rapidity gap and their sum of charges is studied. An excess of leading systems with total charge zero is found for gluon jets in all cases, when compared to Monte Carlo Simulations with JETSET (with and without Bose-Einstein correlations included) and ARIADNE. The corresponding leading systems of quark jets do not exhibit such an excess. The influence of the gap size and of the gluon purity on the effect is studied and a concentration of the excess of neutral leading systems at low invariant masses (<~ 2 GeV/c^2) is observed, indicating that gluon jets might have an additional hitherto undetected fragmentation mode via a two-gluon system. This could be an indication of a possible production of gluonic states as predicted by QCD.Comment: 19 pages, 6 figures, Accepted by Phys. Lett.

Measurement and Interpretation of Fermion-Pair Production at LEP energies above the Z Resonance

This paper presents DELPHI measurements and interpretations of cross-sections, forward-backward asymmetries, and angular distributions, for the e+e- -> ffbar process for centre-of-mass energies above the Z resonance, from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are consistent with the predictions of the Standard Model and are used to study a variety of models including the S-Matrix ansatz for e+e- -> ffbar scattering and several models which include physics beyond the Standard Model: the exchange of Z' bosons, contact interactions between fermions, the exchange of gravitons in large extra dimensions and the exchange of sneutrino in R-parity violating supersymmetry.Comment: 79 pages, 16 figures, Accepted by Eur. Phys. J.

A Determination of the Centre-of-Mass Energy at LEP2 using Radiative 2-fermion Events

Using e+e- -> mu+mu-(gamma) and e+e- -> qqbar(gamma) events radiative to the Z pole, DELPHI has determined the centre-of-mass energy, sqrt{s}, using energy and momentum constraint methods. The results are expressed as deviations from the nominal LEP centre-of-mass energy, measured using other techniques. The results are found to be compatible with the LEP Energy Working Group estimates for a combination of the 1997 to 2000 data sets.Comment: 20 pages, 6 figures, Accepted by Eur. Phys. J.

Study of Inclusive J/psi Production in Two-Photon Collisions at LEP II with the DELPHI Detector

Inclusive J/psi production in photon-photon collisions has been observed at LEP II beam energies. A clear signal from the reaction gamma gamma -> J/psi+X is seen. The number of observed N(J/psi -> mu+mu-) events is 36 +/- 7 for an integrated luminosity of 617 pb^{-1}, yielding a cross-section of sigma(J/psi+X) = 45 +/- 9 (stat) +/- 17 (syst) pb. Based on a study of the event shapes of different types of gamma gamma processes in the PYTHIA program, we conclude that (74 +/- 22)% of the observed J/psi events are due to `resolved' photons, the dominant contribution of which is most probably due to the gluon content of the photon.Comment: 13 pages, 8 figures, Accepted by Phys. Lett.

Evidence for an Excess of Soft Photons in Hadronic Decays of Z^0

Soft photons inside hadronic jets converted in front of the DELPHI main tracker (TPC) in events of qqbar disintegrations of the Z^0 were studied in the kinematic range 0.2 < E_gamma < 1 GeV and transverse momentum with respect to the closest jet direction p_T < 80 MeV/c. A clear excess of photons in the experimental data as compared to the Monte Carlo predictions is observed. This excess (uncorrected for the photon detection efficiency) is (1.17 +/- 0.06 +/- 0.27) x 10^{-3} gamma/jet in the specified kinematic region, while the expected level of the inner hadronic bremsstrahlung (which is not included in the Monte Carlo) is (0.340 +/- 0.001 +/- 0.038) x 10^{-3} gamma/jet. The ratio of the excess to the predicted bremsstrahlung rate is then (3.4 +/- 0.2 +/- 0.8), which is similar in strength to the anomalous soft photon signal observed in fixed target experiments with hadronic beams.Comment: 37 pages, 9 figures, Accepted by Eur. Phys. J.

A Measurement of the Tau Hadronic Branching Ratios

The exclusive and semi-exclusive branching ratios of the tau lepton hadronic decay modes (h- v_t, h- pi0 v_t, h- pi0 pi0 v_t, h- \geq 2pi0 v_t, h- \geq 3pi0 v_t, 2h- h+ v_t, 2h- h+ pi0 v_t, 2h- h+ \geq 2pi0 v_t, 3h- 2h+ v_t and 3h- 2h+ \geq 1pi0 v_t) were measured with data from the DELPHI detector at LEP.Comment: 53 pages, 18 figures, Accepted by Eur. Phys. J.