Coupling between quasiparticles and a bosonic mode in the normal state of HgBa2_2CuO4+δ_{4+\delta}

We report a doping dependent study of the quasiparticles dynamics in HgBa$_2$CuO$_{4+\delta}$ via Electronic Raman Scattering. A well-defined energy scale is found in the normal state dynamics of the quasiparticles over a broad doping range. It is interpreted as evidence for coupling between the quasiparticles and a collective bosonic mode whose energy scale depend only weakly with doping. We contrast this behavior with that of the superconducting gap whose amplitude near the node continuously decreases towards the underdoped regime. We discuss the implications of our findings on the nature of the collective mode and argue that electron-phonon coupling is the most natural explanation.Comment: 5 pages, 4 figure

Two Energy Scales and two Quasiparticle Dynamics in the Superconducting State of Underdoped Cuprates

The superconducting state of underdoped cuprates is often described in terms of a single energy-scale, associated with the maximum of the (d-wave) gap. Here, we report on electronic Raman scattering results, which show that the gap function in the underdoped regime is characterized by two energy scales, depending on doping in opposite manners. Their ratios to the maximum critical temperature are found to be universal in cuprates. Our experimental results also reveal two different quasiparticle dynamics in the underdoped superconducting state, associated with two regions of momentum space: nodal regions near the zeros of the superconducting gap and antinodal regions. While antinodal quasiparticles quickly loose coherence as doping is reduced, coherent nodal quasiparticles persist down to low doping levels. A theoretical analysis using a new sum-rule allows us to relate the low-frequency-dependence of the Raman response to the temperature-dependence of the superfluid density, both controlled by nodal excitations.Comment: 16 pages, 5 figure

Phonon dispersion in 1-layer cuprate HgBa2CuO4+d

We investigate the low energy acoustical and optical modes in $\mathrm{HgBa_2CuO_{4+\delta}}$ using inelastic x-ray scattering (IXS). The experimental phonon dispersion and the dynamical structure factor are compared with an atomic shell model, and the set of the atomic potentials obtained are discussed. Our results are also compared with those obtained by Raman spectroscopy and with density-of-state data measured by inelastic neutron scattering

Electronic Raman scattering in HgBa_{2}Ca_{2}Cu_{3}O_{8+\delta} single crystals. Analysis of the superconducting state

Electronic Raman scattering measurements have been performed on $HgBa_{2}Ca_{2}Cu_{3}O_{8+\delta}$ single crystals in the superconducting state. Pure electronic Raman spectra with no phonon structures hindering the analysis of the electronic continuum have been obtained. As a consequence, the spectra in the pure $B_{1g}$ and $B_{2g}$ symmetries are directly and reliably analyzed and the pure $A_{1g}$ contribution can be easily identified. Below the critical temperature $T_{c},$ two electronic structures at $2\Delta \sim 6.4 k_{B}T_{c}$ and $2\Delta \sim 9.4$ $k_{B}T_{c}$ are clearly seen. Both are observed simultaneously in pure $A_{1g}$ symmetry, the highest energy one being located at the energy of the $B_{1g}$ maximum. These two maxima disappear at $T_{c}$ and do not soften significantly as the temperature is raised up to $T_{c}.$ The low energy frequency dependence of the $B_{1g}$ electronic response is strongly linear, for various excitation lines in the 476.5 to 647.1 nm range. Such experimental data cannot be reconciled with a pure $d_{x^{2}-y^{2}}$ symmetry. Instead, they strongly advocate in favor of an anisotropic superconducting gap with two distinct gap maxima and of nodes existing outside the [110] and [1,$\bar{1}$,0] directions in {\bf k}-space. We discuss in detail the simplest order parameter compatible with our experimental findings.Comment: 12 pages, revtex, 12 figure

“Be an ambassador for change that you would like to see”: a call to action to all stakeholders for co-creation in healthcare and medical research to improve quality of life of people with a neuromuscular disease

BACKGROUND: Patient and public involvement for co-creation is increasingly recognized as a valuable strategy to develop healthcare research targeting patients’ real needs. However, its practical implementation is not as advanced and unanimously accepted as it could be, due to cultural differences and complexities of managing healthcare programs and clinical studies, especially in the rare disease field. MAIN BODY: The European Neuromuscular Centre, a European foundation of patient organizations, involved its key stakeholders in a special workshop to investigate the position of the neuromuscular patient community with respect to healthcare and medical research to identify and address gaps and bottlenecks. The workshop took place in Milan (Italy) on January 19–20, 2018, involving 45 participants who were mainly representatives of the patient community, but also included experts from clinical centers, industry and regulatory bodies. In order to provide practical examples and constructive suggestions, specific topics were identified upfront. The first set of issues concerned the quality of life at specific phases of a patient’s life, such as at the time of diagnosis or during pediatric to adult transition, and patient involvement in medical research on activities in daily living including patient reported outcome measures. The second set of issues concerned the involvement of patients in the management of clinical research tools, such as registries and biobanks, and their participation in study design or marketing authorization processes. Introductory presentations were followed by parallel working group sessions, to gain constructive contributions from all participants. The concept of shared decision making was used to ensure, in discussions, a partnership-based identification of the wishes and needs of all stakeholders involved, and the “ladder of participation” tool served as a model to evaluate the actual and the desired level of patients’ involvement in all topics addressed. A general consensus on the outcome of the meeting was collected during the final plenary session. This paper reports the outcome of the workshop and the specific suggestions derived from the analysis of the first set of topics, related to quality of life. The outcomes of the second set of topics are reported elsewhere and are only briefly summarized herein for the sake of completeness. CONCLUSIONS: The neuromuscular community proved to be very active and engaged at different levels in the healthcare initiatives of interest. The workshop participants critically discussed several topics, providing practical examples where different stakeholders could play a role in making a change and bridging gaps. Overall, they indicated the need for education of all stakeholders for better communication, where everyone should become an ambassador to promote real change. Support should also come from institutions and healthcare bodies both at structural and economic level

Enantioselective oxidation of 1,3-dithioacetals catalysed by cyclohexanone monooxygenase

Cyclohexanone monooxygenase catalysed oxidation of dithioacetals in combination with kinetic resolution gives enantiomerically pure (R)-monosulfoxides

A displacive periodic antiphase model for one-dimensional platinum chain compounds

From room temperature investigations we propose a displacive periodic antiphase model for the 1-dimensional compound COdef[Pt(C2O 4)2].xH2O. This model, which interrelates in a simple way the various discrete satellites, accounts for the 3-dimensional distortions present in the structure independently of the uncorrelated modulation of the Pt chains evidenced by diffuse planes at room temperature.A partir d'une étude faite à la température ambiante nous proposons un modèle d'antiphase périodique displacive pour le composé unidimensionnel COdef[Pt(C2O4)2].xH 2O. Ce modèle, qui relie de manière simple les divers satellites discrets, rend compte des distorsions 3-dimensionnelles présentes dans la structure indépendamment de la modulation non corrélée des chaines de platine, laquelle se traduit par des plans de diffusion continue à la température ambiante