Evidence for a spin acoustic surface plasmon from inelastic atom scattering.

Closed-shell atoms scattered from a metal surface exchange energy and momentum with surface phonons mostly via the interposed surface valence electrons, i.e., via the creation of virtual electron-hole pairs. The latter can then decay into surface phonons via electron-phonon interaction, as well as into acoustic surface plasmons (ASPs). While the first channel is the basis of the current inelastic atom scattering (IAS) surface-phonon spectroscopy, no attempt to observe ASPs with IAS has been made so far. In this study we provide evidence of ASP in Ni(111) with both Ne atom scattering and He atom scattering. While the former measurements confirm and extend so far unexplained data, the latter illustrate the coupling of ASP with phonons inside the surface-projected phonon continuum, leading to a substantial reduction of the ASP velocity and possibly to avoided crossing with the optical surface phonon branches. The analysis is substantiated by a self-consistent calculation of the surface response function to atom collisions and of the first-principle surface-phonon dynamics of Ni(111). It is shown that in Ni(111) ASP originate from the majority-spin Shockley surface state and are therefore collective oscillation of surface electrons with the same spin, i.e. it represents a new kind of collective quasiparticle: a Spin Acoustic Surface Plasmon (SASP).

The electron-phonon interaction at deep Bi 2 Te3-semiconductor interfaces from Brillouin light scattering.

It is shown that the electron-phonon interaction at a conducting interface between a topological insulator thin film and a semiconductor substrate can be directly probed by means of high-resolution Brillouin light scattering (BLS). The observation of Kohn anomalies in the surface phonon dispersion curves of a 50 nm thick Bi2Te3 film on GaAs, besides demonstrating important electron-phonon coupling effects in the GHz frequency domain, shows that information on deep interface electrons can be obtained by tuning the penetration depth of optically-generated surface phonons so as to selectively probe the interface region, as in a sort of quantum sonar.

Surface lattice dynamics and electron-phonon interaction in cesium ultra-thin films.

The phonon dispersion curves of ultrathin films of Cs(110) on Pt(111) measured with inelastic helium atom scattering (HAS) are reported and compared with density-functional perturbation theory (DFPT) calculations. The combined HAS and DFPT analysis also sheds light on the bulk phonon dynamics of bcc-Cs, on which very little is known from neutron scattering due to its large neutron capture cross-section. Moreover the temperature dependence of the elastic HAS Debye-Waller exponent of Cs(110)/Cu(111) ultrathin films allows for an estimation of the electron-phonon coupling strength λ as a function of the film thickness.

Indium selenide: an insight into electronic band structure and surface excitations.

We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at ~1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed.

Novel near-infrared emission from crystal defects in MoS2 multilayer flakes.

The structural defects in two-dimensional transition metal dichalcogenides, including point defects, dislocations and grain boundaries, are scarcely considered regarding their potential to manipulate the electrical and optical properties of this class of materials, notwithstanding the significant advances already made. Indeed, impurities and vacancies may influence the exciton population, create disorder-induced localization, as well as modify the electrical behaviour of the material. Here we report on the experimental evidence, confirmed by ab initio calculations, that sulfur vacancies give rise to a novel near-infrared emission peak around 0.75 eV in exfoliated MoS2 flakes. In addition, we demonstrate an excess of sulfur vacancies at the flake's edges by means of cathodoluminescence mapping, aberration-corrected transmission electron microscopy imaging and electron energy loss analyses. Moreover, we show that ripplocations, extended line defects peculiar to this material, broaden and redshift the MoS2 indirect bandgap emission.

Electron-phonon interaction and thermal boundary resistance at the interfaces of Ge2Sb2Te5 with metals and dielectrics.

The Ge2Sb2Te5 compound is of interest for applications in phase change non-volatile memories. First-principles calculations of phonon dispersion relations and electron-phonon coupling constant provide an estimate of the electron-phonon contribution to the thermal boundary resistance at the interfaces of Ge2Sb2Te5 with dielectrics (silica) and metal electrodes (Al and TiN). The diffuse mismatch model including full phononic dispersion has been used to compute the phononic contribution to the thermal boundary resistance. The calculated value of the electron-phonon contribution to the TBR at 300 K of about 14 m(2)K GW(-1) would dominate the TBR at the interfaces of hexagonal Ge2Sb2Te5 with the surrounding dielectrics and metals considered here once interdiffusion at the boundaries could be minimized.

Unveiling mode-selected electron-phonon interactions in metal films by helium atom scattering.

The quasi two-dimensional electron gas on a metal film can transmit to the surface even minute mechanical disturbances occurring in the depth, thus allowing the gentlest of all surface probes, helium atoms, to perceive the vibrations of the deepest atoms via the induced surface-charge density oscillations. A density functional perturbation theory (DFPT) and a helium atom scattering study of the phonon dispersion curves in lead films of up to 7 mono-layers on a copper substrate show that: (a) the electron-phonon interaction is responsible for the coupling of He atoms to in-depth phonon modes; and (b) the inelastic HAS intensity from a given phonon mode is proportional to its electron-phonon coupling. The direct determination of mode-selected electron-phonon coupling strengths has great relevance for understanding superconductivity in thin films and two-dimensional systems.

[Acute parotiditis after tracheostomy in Intensive Care]. / Parotiditis aguda tras traqueotomía en Cuidados Intensivos.

Post-anesthesic parotiditis is a little known entity related with anesthesic procedures but described in any situation that motivates manipulation of the oropharyngeal cavity. Its physiopathological mechanism is not well-defined, although it could have a multifactorial origin. A case of a male who was admitted for post-operative control of brain tumor exeresis and who had preauricular and submaxillary inflammation after a routinely performed tracheostomy is presented. Coincidence with the performing of a tracheostomy required us to propose the differential diagnosis with the complications associated to said surgical act. Post-anesthesic parotiditis, even though it is a rare complication and has no clinical significance, should be kept in mind when there is facial edema after any manipulation of the oropharyngeal cavity.

Parotiditis aguda tras traqueotomía en Cuidados Intensivos / Acute parotiditis after tracheostomy in Intensive Care

La parotiditis postanestésica es una entidad poco conocida, relacionada con procedimientos anestésicos pero descrita ante cualquier situación que motiva una manipulación de la cavidad orofaríngea. Su mecanismo fisiopatológico no está bien definido aunque podría ser de origen multifactorial. Se presenta el caso de un varón que ingresó para control postoperatorio de exéresis de tumor cerebral y que tras una traqueotomía realizada de forma rutinaria presenta una inflamación a nivel preauricular y submaxilar. La coincidencia con la realización de traqueotomía nos obligó a plantearnos el diagnóstico diferencial con las complicaciones asociadas a dicho acto quirúrgico. La parotiditis postanestésica, aun tratándose de una complicación poco frecuente y sin trascendencia clínica, debe tenerse en cuenta ante la aparición de edema facial tras cualquier manipulación de la cavidad orofaríngea

Post-anesthesic parotiditis is a little known entity related with anesthesic procedures but described in any situation that motivates manipulation of the oropharyngeal cavity. Its physiopathological mechanism is not well-defined, although it could have a multifactorial origin. A case of a male who was admitted for post-operative control of brain tumor exeresis and who had preauricular and submaxillary inflammation after a routinely performed tracheostomy is presented. Coincidence with the performing of a tracheostomy required us to propose the differential diagnosis with the complications associated to said surgical act. Post-anesthesic parotiditis, even though it is a rare complication and has no clinical significance, should be kept in mind when there is facial edema after any manipulation of the oropharyngeal cavity

Prevención del síndrome respiratorio agudo grave en la unidad de cuidados intensivos / Prevention of severe respiratory syndrome in the intensive care unit

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Expanding DIOGENE with a clinical information system based on a new hospital-wide clinical findings dictionary.

The DIOGENE hospital information system has been expanded with a centralized and integrated patient clinical database recording structured patient data. The objective is to provide a standardized framework for the building of future clinical databases and for the integration of existing heterogeneous ones. The combined 'across time view' and 'across departments view' generated from the integrated clinical data will enable an evolutionary view of the patient state, both across time and across medical specialties. For this purpose and to permit the communication and exchange of data, a new controlled vocabulary for representing clinical data has been created. The construction of this vocabulary is based on the international ICD classification, already being used in DIOGENE for encoding patient diagnosis and procedures. A new extension of the ICD is proposed for medical information that goes beyond diagnosis and procedures encoding. The building of a common clinical findings dictionary, recording the definition of clinical entities, is based on this newly developed clinical vocabulary. This process is incremental, manual and substantial.

ARCHIMED: a Network of Integrated Information Systems.

ARCHIMED is a Network of Integrated Information Systems (NIIS). This novel concept of hospital information system has a major advantage over the currently used distributed systems. The normalized representation structure of its databases enable its Navigators to reach simultaneously not only the data coming from different hospital departments, laboratories, and other hospital facilities, but also the data from different hospitals associated in the network.

A hospital-wide clinical findings dictionary based on an extension of the International Classification of Diseases (ICD).

The use of a controlled vocabulary set in a hospital-wide clinical information system is of crucial importance for many departmental database systems to communicate and exchange information. In the absence of an internationally recognized clinical controlled vocabulary set, a new extension of the International statistical Classification of Diseases (ICD) is proposed. It expands the scope of the standard ICD beyond diagnosis and procedures to clinical terminology. In addition, the common Clinical Findings Dictionary (CFD) further records the definition of clinical entities. The construction of the vocabulary set and the CFD is incremental and manual. Tools have been implemented to facilitate the tasks of defining/maintaining/publishing dictionary versions. The design of database applications in the integrated clinical information system is driven by the CFD which is part of the Medical Questionnaire Designer tool. Several integrated clinical database applications in the field of diabetes and neuro-surgery have been developed at the HUG.

The bridge between administrative and clinical information system.

On one side, physicians are asked to record administrative information, such as activity measurement, case-mix of their specialty, billing, for statistical, legal or reimbursement purposes; and on the other side, they need to gather detailed information about their own patients in terms of clinical evolution, for the day-to-day care of the patients or for clinical research purposes. Many other actors are also involved with these processes, both on the administrative side, such as registration officers, administrators and on the clinical side, nurses and other care providers. Applications have been developed within hospital information systems for capturing and disseminating information according to these specific actors and dedicated purposes. But more and more appears the need to integrate these data for insuring the coherence of information and avoiding redundancy of data capture. How to conciliate these objectives? We describe the Geneva's approach for integrating the administrative and the clinical systems.

Expanding DIOGENE with a clinical information system based on a new hospital-wide clinical finding dictionary.

The aim of this project is to expand DIOGENE with a centralized and integrated patient clinical database system providing a standardized framework for the building of future clinical databases and for the integration of existing heterogeneous ones. The combined 'across time view' and 'across departments view' generated from the integrated clinical data will enable an evolutionary view of the patient state both across time and across medical specialties. For this purpose and to permit the communication and exchange of data, a new controlled vocabulary for representing clinical data has been created. The construction of this vocabulary is based on the international ICD classification, already being used in DIOGENE for encoding patient diagnosis and procedures. A new extension of the ICD is proposed for medical information that goes beyond diagnosis and procedures encoding. The building of a common clinical finding dictionary recording the definition of findings is based on this newly developed clinical vocabulary. This process is incremental, manual, and significant.

All-optical switching in distributed-feedback muiltiple-quantum-well waveguides.

We discuss experimental results that demonstrate all-optical switching and pulse-routing functionality, at 1.55 um, of nonlinear multiple-quantum-well waveguides equipped with a Bragg grating. Basing on the nonlinear Time-Domain Beam Propagation Method, the switching behavior has been theoretically investigated using a model, developed as part of this work.

All-optical switching and pulse routing in a distributed-feedback waveguide device.

Results of all-optical switching and pulse-routing experiments with a distributed-feedback multiple-quantum-well (MQW) nonlinear waveguide, operating at 1.55microm , are reported. The MQW material has been engineered, through the controlled introduction of defects, to lower the carrier lifetime from 2.5 ns to 280 ps. The energy required for switching is of the order of 1 pJ or less, the switching time is ~600 ps , and the on-off contrast exceeds 17 dB.