Comment on "Feshbach-Einstein Condensates" by V. G. Rousseau and P. J. H. Denteneer

In a recent paper (Phys. Rev. Lett. 102, 015301 (2009), arXiv:0810.3763) Rousseau and Denteneer claim that an unconventional "super-Mott" (SM) phase is realized by bosons trapped in an optical lattice close to a Feshbach resonance with a molecular state. The supposed SM phase, observed via quantum Monte Carlo (QMC) simulations of an atom-molecule Bose-Hubbard model, is an incompressible phase developing spontaneous atomic/molecular supercurrents which are perfectly anticorrelated. Here we show that the identification of this phase is based on a misinterpretation of the estimators of superfluidity in QMC, which break down in the presence of coherent atom/molecule conversion. Our conclusion is that the supposed SM phase is in fact a fully normal insulator.Comment: 1+epsilon page, 1 figur

Correlated hopping of bosonic atoms induced by optical lattices

In this work we analyze a particular setup with ultracold atoms trapped in state-dependent lattices. We show that any asymmetry in the contact interaction translates into one of two classes of correlated hopping. After deriving the effective lattice Hamiltonian for the atoms, we obtain analytically and numerically the different phases and quantum phase transitions. We find for weak correlated hopping both Mott insulators and charge density waves, while for stronger correlated hopping the system transitions into a pair superfluid. We demonstrate that this phase exists for a wide range of interaction asymmetries and has interesting correlation properties that differentiate it from an ordinary atomic Bose-Einstein condensate.Comment: 24 pages with 9 figures, to appear in New Journal of Physic

La coordinación de actividades empresariales de trabajadores desplazados en la construcción.

Cada vez está más interiorizada por las empresas la necesidad de tener procedimientos específicos para llevar a cabo la coordinación de actividades empresariales. Pese a que la el Real Decreto de Coordinación de Actividades que salió en 2004, no es, en absoluto, una obligación que ya esté superada, especialmente en el caso de la pequeña y mediana empresa. Por si esto fuera poco, la internacionalización y globalización de las empresas añaden un ingrediente más a esta situación. Considerando que en la Unión Europea, el hecho de ser un trabajador comunitario o no serlo hace que la coordinación empresarial tenga connotaciones muy diferentes, el trabajo que a continuación se presenta pretende, en primer lugar, aclarar conceptos básicos relativos a las relaciones laborales que se establecen entre empresas de diferentes países, analizando especialmente el ámbito de la coordinación de actividades empresariales. En segundo lugar, aclarar y facilitar la identificación y comprensión de la documentación que las empresas han de generar ante el traslado temporal de sus trabajadores a empresas extranjeras y de trabajadores de empresas extranjeras a sus instalaciones. Así mismo quiere dejar claras las sanciones a las que se enfrentan los que no cumplen este punto de la legislación. Creando un cuadro resumen que sirva como guía para facilitar la coordinación de actividades empresariales para trabajadores desplazados del sector de la construcción

Evolution over Time of Ventilatory Management and Outcome of Patients with Neurologic Disease∗

OBJECTIVES: To describe the changes in ventilator management over time in patients with neurologic disease at ICU admission and to estimate factors associated with 28-day hospital mortality. DESIGN: Secondary analysis of three prospective, observational, multicenter studies. SETTING: Cohort studies conducted in 2004, 2010, and 2016. PATIENTS: Adult patients who received mechanical ventilation for more than 12 hours. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among the 20,929 patients enrolled, we included 4,152 (20%) mechanically ventilated patients due to different neurologic diseases. Hemorrhagic stroke and brain trauma were the most common pathologies associated with the need for mechanical ventilation. Although volume-cycled ventilation remained the preferred ventilation mode, there was a significant (p < 0.001) increment in the use of pressure support ventilation. The proportion of patients receiving a protective lung ventilation strategy was increased over time: 47% in 2004, 63% in 2010, and 65% in 2016 (p < 0.001), as well as the duration of protective ventilation strategies: 406 days per 1,000 mechanical ventilation days in 2004, 523 days per 1,000 mechanical ventilation days in 2010, and 585 days per 1,000 mechanical ventilation days in 2016 (p < 0.001). There were no differences in the length of stay in the ICU, mortality in the ICU, and mortality in hospital from 2004 to 2016. Independent risk factors for 28-day mortality were age greater than 75 years, Simplified Acute Physiology Score II greater than 50, the occurrence of organ dysfunction within first 48 hours after brain injury, and specific neurologic diseases such as hemorrhagic stroke, ischemic stroke, and brain trauma. CONCLUSIONS: More lung-protective ventilatory strategies have been implemented over years in neurologic patients with no effect on pulmonary complications or on survival. We found several prognostic factors on mortality such as advanced age, the severity of the disease, organ dysfunctions, and the etiology of neurologic disease