Preparación y caracterización de óxidos de manganeso no estequiométricos

Se describe la preparación y caracterización fisicoquímica por diversas técnicas (análisis químico elemental, difracción de rayos X, espectroscopía FT-IR, análisis térmico y determinación de superficie específica) de birnesitas de Na, K y Li preparadas por diversos métodos. Asimismo, se han estudiado sus propiedades de cambio iónico, caracterizando las muestras intercambiadas por las mismas técnicas. Se ha encontrado que el intercambio es prácticamente total en el caso del Li, mientras que en el caso de Cu y Mg el porcentaje intercambiado es relativamente bajo.Peer reviewe

Study of η − η′ mixing from measurement of B (s)0 → J/ψη(′) decay rates

A study of B and B0 s meson decays into J/ψη and J/ψη0 final states is performed using a data set of proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, collected by the LCHb experiment and corresponding to 3.0 fb−1 of integrated luminosity. The decay B0 → J/ψη0 is observed for the first time. The following ratios of branching fractions are measured: B(B0 → J/ψη0 ) B(B0 s → J/ψη0) = (2.28 ± 0.65 (stat) ± 0.10 (syst) ± 0.13 (fs/fd)) × 10−2 , B(B0 → J/ψη) B(B0 s → J/ψη) = (1.85 ± 0.61 (stat) ± 0.09 (syst) ± 0.11 (fs/fd)) × 10−2 , where the third uncertainty is related to the present knowledge of fs/fd, the ratio between the probabilities for a b quark to form a B0 s or a B0 meson. The branching fraction ratios are used to determine the parameters of η−η 0 meson mixing. In addition, the first evidence for the decay B0 s → ψ(2S)η 0 is reported, and the relative branching fraction is measured, B(B0 s → ψ(2S)η 0 ) B(B0 s → J/ψη0) = (38.7 ± 9.0 (stat) ± 1.3 (syst) ± 0.9(B)) × 10−2 , where the third uncertainty is due to the limited knowledge of the branching fractions of J/ψ and ψ(2S) mesons

Angular analysis and differential branching fraction of the decay B {/s 0} → ϕμ + μ -

An angular analysis and a measurement of the differential branching fraction of the decay B0 s → φµ+µ − are presented, using data corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions recorded by the LHCb experiment at √ s = 7 and 8 TeV. Measurements are reported as a function of q 2 , the square of the dimuon invariant mass and results of the angular analysis are found to be consistent with the Standard Model. In the range 1 < q2 < 6 GeV2/c4 , where precise theoretical calculations are available, the differential branching fraction is found to be more than 3 σ below the Standard Model predictions

Observation of the B0 →ρ0ρ0 decay from an amplitude analysis of B0 → (π+π-) (π+π-) decays

Proton-proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb−1 , are analysed to search for the charmless B0 → ρ 0ρ 0 decay. More than 600 B0 → (π +π −)(π +π −) signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0 → ρ 0ρ 0 decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0 → ρ 0ρ 0 decays yielding a longitudinally polarised final state is measured to be fL = 0.745+0.048 −0.058(stat) ± 0.034(syst). The B0 → ρ 0ρ 0 branching fraction, using the B0 → φK∗ (892)0 decay as reference, is also reported as B(B0 → ρ 0ρ 0 ) = (0.94 ± 0.17(stat) ± 0.09(syst) ± 0.06(BF)) × 10−6

Functional cartography of complex metabolic networks

High-throughput techniques are leading to an explosive growth in the size of biological databases and creating the opportunity to revolutionize our understanding of life and disease. Interpretation of these data remains, however, a major scientific challenge. Here, we propose a methodology that enables us to extract and display information contained in complex networks. Specifically, we demonstrate that one can (i) find functional modules in complex networks, and (ii) classify nodes into universal roles according to their pattern of intra- and inter-module connections. The method thus yields a ``cartographic representation'' of complex networks. Metabolic networks are among the most challenging biological networks and, arguably, the ones with more potential for immediate applicability. We use our method to analyze the metabolic networks of twelve organisms from three different super-kingdoms. We find that, typically, 80% of the nodes are only connected to other nodes within their respective modules, and that nodes with different roles are affected by different evolutionary constraints and pressures. Remarkably, we find that low-degree metabolites that connect different modules are more conserved than hubs whose links are mostly within a single module.Comment: 17 pages, 4 figures. Go to http://amaral.northwestern.edu for the PDF file of the reprin

Unusual presentation of thyrotoxicosis as complete heart block and renal failure: a case report

<p>Abstract</p> <p>Introduction</p> <p>Thyrotoxicosis is a clinical entity often very difficult to diagnose without biochemical confirmation as its clinical features can be highly varied. The most common cardiac manifestations of thyrotoxicosis are resting sinus tachycardia, supraventricular tachycardia including atrial fibrillation and atrial flutter with or without cardiac failure. Bradycardia and atrio-ventricular conduction defects are very uncommon in thyrotoxicosis.</p> <p>Case presentation</p> <p>We report the case of a 59-year-old Caucasian man presenting with progressive weight loss, abnormal liver function, acute renal failure and complete heart block due to thyrotoxicosis.</p> <p>Conclusion</p> <p>Thyrotoxicosis should be considered as a possible diagnosis in patients with bradycardia and heart blocks associated with abnormal symptoms like weight loss. Nevertheless, the clinical, electrophysiological and biochemical abnormalities associated with thyrotoxicosis may be completely reversible restoring euthyroid state.</p

Searches for Λ0b and Ξ0b decays to K0Spπ− and K0SpK− final states with first observation of the Λ0b→K0Spπ− decay

A search for previously unobserved decays of beauty baryons to the final states K0 S pπ− and K0 S pK− is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb−1 of pp collisions. The Λ 0 b → K0pπ− decay is observed with a significance of 8.6 σ, with branching fraction B(Λ 0 b → K0 pπ−) = (1.26 ± 0.19 ± 0.09 ± 0.34 ± 0.05) × 10−5 , where the uncertainties are statistical, systematic, from the ratio of fragmentation fractions fΛ0 b /fd, and from the branching fraction of the B0→ K0π +π − normalisation channel, respectively. A first measurement is made of the CP asymmetry, giving ACP (Λ 0 b → K0 pπ−) = 0.22 ± 0.13 (stat) ± 0.03 (syst). No significant signals are seen for Λ 0 b → K0 S pK− decays, Ξ0 b decays to both the K0 S pπ− and K0 S pK− final states, and the Λ 0 b → D− s (→ K0 SK−)p decay, and upper limits on their branching fractions are reported

Observation of Z production in proton-lead collisions at LHCb

The first observation of Z boson production in proton-lead collisions at a centreof-mass energy per proton-nucleon pair of √ sNN = 5 TeV is presented. The data sample corresponds to an integrated luminosity of 1.6 nb−1 collected with the LHCb detector. The Z candidates are reconstructed from pairs of oppositely charged muons with pseudorapidities between 2.0 and 4.5 and transverse momenta above 20 GeV/c. The invariant dimuon mass is restricted to the range 60 − 120 GeV/c2 . The Z production cross-section is measured to be σZ→µ+µ− (fwd) = 13.5 +5.4 −4.0 (stat.) ± 1.2(syst.) nb in the direction of the proton beam and σZ→µ+µ− (bwd) = 10.7 +8.4 −5.1 (stat.) ± 1.0(syst.) nb in the direction of the lead beam, where the first uncertainty is statistical and the second systematic

Quantum numbers of the X (3872 ) state and orbital angular momentum in its ρ0J /ψ decay

Angular correlations in B+ → X(3872)K+ decays, with X(3872) → ρ 0J/ψ, ρ 0 → π +π − and J/ψ → µ +µ −, are used to measure orbital angular momentum contributions and to determine the J P C value of the X(3872) meson. The data correspond to an integrated luminosity of 3.0 fb−1 of proton-proton collisions collected with the LHCb detector. This determination, for the first time performed without assuming a value for the orbital angular momentum, confirms the quantum numbers to be J P C = 1++. The X(3872) is found to decay predominantly through S wave and an upper limit of 4% at 95% C.L. is set on the D-wave contribution

Dalitz plot analysis of B0→D¯0π+π- decays

The resonant substructures of B0 → D0π +π − decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions collected by the LHCb detector is used. The branching fraction of the B0 → D0π +π − decay in the region m(D0π ±) > 2.1 GeV/c2 is measured to be (8.46 ± 0.14 ± 0.29 ± 0.40) × 10−4 , where the first uncertainty is statistical, the second is systematic and the last arises from the normalisation channel B0 → D∗ (2010)−π +. The π +π − S-wave components are modelled with the Isobar and K-matrix formalisms. Results of the Dalitz plot analyses using both models are presented. A resonant structure at m(D0π −) ≈ 2.8 GeV/c2 is confirmed and its spin-parity is determined for the first time as J P = 3−. The branching fraction, mass and width of this structure are determined together with those of the D∗ 0 (2400)− and D∗ 2 (2460)− resonances. The branching fractions of other B0 → D0h 0 decay components with h 0 → π +π − are also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays B0 → D0f0(500), B0 → D0f0(980), B0 → D0ρ(1450), B0 → D∗ 3 (2760)−π + and the first evidence of B0 → D0f0(2020) are presented