Azathioprine and 6-Mercaptopurine use in the Swiss IBD cohort : adverse effects, causes of discontinuation and risk of "flares" according to 6-TG levels

Background: To characterize and analyze in the Swiss IBD Cohort: a) reported Azathioprine (AZA) and 6-Mercaptopurine (6-MP) adverse effects (AE), b) causes of discontinuation and c) response to therapy according to gastroenterologists' clinical judgment, d) whether level of 6-TGN < 235pmol/8 x108 red blood cells (RBC) is associated with a higher risk of "flare" occurrence. Methods: Retrospective statistical description, Cox model and Kaplan-Meier survival estimation. Results: 1499 patients with Crohn's Disease (CD) and 1066 with Ulcerative colitis (UC)

Mechanisms of Improved Exercise Performance under Hyperoxia

BACKGROUND The impact of hyperoxia on exercise limitation is still incompletely understood. OBJECTIVES We investigated to which extent breathing hyperoxia enhances the exercise performance of healthy subjects and which physiologic mechanisms are involved. METHODS A total of 32 healthy volunteers (43 ± 15 years, 12 women) performed 4 bicycle exercise tests to exhaustion with ramp and constant-load protocols (at 75% of the maximal workload [Wmax] on FiO2 0.21) on separate occasions while breathing ambient (FiO2 0.21) or oxygen-enriched air (FiO2 0.50) in a random, blinded order. Workload, endurance, gas exchange, pulse oximetry (SpO2), and cerebral (CTO) and quadriceps muscle tissue oxygenation (QMTO) were measured. RESULTS During the final 15 s of ramp exercising with FiO2 0.50, Wmax (mean ± SD 270 ± 80 W), SpO2 (99 ± 1%), and CTO (67 ± 9%) were higher and the Borg CR10 Scale dyspnea score was lower (4.8 ± 2.2) than the corresponding values with FiO2 0.21 (Wmax 257 ± 76 W, SpO2 96 ± 3%, CTO 61 ± 9%, and Borg CR10 Scale dyspnea score 5.7 ± 2.6, p < 0.05, all comparisons). In constant-load exercising with FiO2 0.50, endurance was longer than with FiO2 0.21 (16 min 22 s ± 7 min 39 s vs. 10 min 47 s ± 5 min 58 s). With FiO2 0.50, SpO2 (99 ± 0%) and QMTO (69 ± 8%) were higher than the corresponding isotime values to end-exercise with FiO2 0.21 (SpO2 96 ± 4%, QMTO 66 ± 9%), while minute ventilation was lower in hyperoxia (82 ± 18 vs. 93 ± 23 L/min, p < 0.05, all comparisons). CONCLUSION In healthy subjects, hyperoxia increased maximal power output and endurance. It improved arterial, cerebral, and muscle tissue oxygenation, while minute ventilation and dyspnea perception were reduced. The findings suggest that hyperoxia enhanced cycling performance through a more efficient pulmonary gas exchange and a greater availability of oxygen to muscles and the brain (cerebral motor and sensory neurons)

Charge redistribution at Pd surfaces: ab initio grounds for tight-binding interatomic potentials

A simplified tight-binding description of the electronic structure is often necessary for complex studies of surfaces of transition metal compounds. This requires a self-consistent parametrization of the charge redistribution, which is not obvious for late transition series elements (such as Pd, Cu, Au), for which not only d but also s-p electrons have to be taken into account. We show here, with the help of an ab initio FP-LMTO approach, that for these elements the electronic charge is unchanged from bulk to the surface, not only per site but also per orbital. This implies different level shifts for each orbital in order to achieve this orbital neutrality rule. Our results invalidate any neutrality rule which would allow charge redistribution between orbitals to ensure a common rigid shift for all of them. Moreover, in the case of Pd, the power law which governs the variation of band energy with respect to coordination number, is found to differ significantly from the usual tight-binding square root.Comment: 6 pages, 2 figures, Latex; Phys.Rev. B 56 (1997

AO-4025 ITT ESA - Surface treatments and coatings for reduction of multipactor and Passive InterModulation (PIM) effect in RF components

This is the electronic version of a paper presented at the 4th International Workshop on Multipactor, Corona and Passive Intermodulation in Space RF Hardware (MULCOPIM 2003) held in Noordwijk, The Netherlands.ESA has initiated several activities with the aim to reduce the risk of multipaction and corona effects in space hardware. Within the activity Surface Treatment and Coating for the Reduction of Multipactor and Passive Intermodulation (PIM) Effects in RF Components a European group has been formed to investigate new surface coatings / treatments to improve the power handling capability of passive equipment with respect to multipactor and passive intermodulation. This paper presents an overview of the activities to be performed within this project and describes the first results

Surfactant effect in heteroepitaxial growth. The Pb - Co/Cu(111) case

A MonteCarlo simulations study has been performed in order to study the effect of Pb as surfactant on the initial growth stage of Co/Cu(111). The main characteristics of Co growing over Cu(111) face, i.e. the decorated double layer steps, the multiple layer islands and the pools of vacancies, disappear with the pre-evaporation of a Pb monolayer. Through MC simulations, a full picture of these complex processes is obtained. Co quickly diffuses through the Pb monolayer exchanging place with Cu atoms at the substrate. The exchange process diffusion inhibits the formation of pure Co islands, reducing the surface stress and then the formation of multilayer islands and the pools of vacancies. On the other hand, the random exchange also suppress the nucleation preferential sites generated by Co atoms at Cu steps, responsible of the step decoration.Comment: 4 pages, latex, 2 figures embedded in the tex

A Geometric Formulation of Quantum Stress Fields

We present a derivation of the stress field for an interacting quantum system within the framework of local density functional theory. The formulation is geometric in nature and exploits the relationship between the strain tensor field and Riemannian metric tensor field. Within this formulation, we demonstrate that the stress field is unique up to a single ambiguous parameter. The ambiguity is due to the non-unique dependence of the kinetic energy on the metric tensor. To illustrate this formalism, we compute the pressure field for two phases of solid molecular hydrogen. Furthermore, we demonstrate that qualitative results obtained by interpreting the hydrogen pressure field are not influenced by the presence of the kinetic ambiguity.Comment: 22 pages, 2 figures. Submitted to Physical Review B. This paper supersedes cond-mat/000627

Effects of anharmonic strain on phase stability of epitaxial films and superlattices: applications to noble metals

Epitaxial strain energies of epitaxial films and bulk superlattices are studied via first-principles total energy calculations using the local-density approximation. Anharmonic effects due to large lattice mismatch, beyond the reach of the harmonic elasticity theory, are found to be very important in Cu/Au (lattice mismatch 12%), Cu/Ag (12%) and Ni/Au (15%). We find that is the elastically soft direction for biaxial expansion of Cu and Ni, but it is for large biaxial compression of Cu, Ag, and Au. The stability of superlattices is discussed in terms of the coherency strain and interfacial energies. We find that in phase-separating systems such as Cu-Ag the superlattice formation energies decrease with superlattice period, and the interfacial energy is positive. Superlattices are formed easiest on (001) and hardest on (111) substrates. For ordering systems, such as Cu-Au and Ag-Au, the formation energy of superlattices increases with period, and interfacial energies are negative. These superlattices are formed easiest on (001) or (110) and hardest on (111) substrates. For Ni-Au we find a hybrid behavior: superlattices along and like in phase-separating systems, while for they behave like in ordering systems. Finally, recent experimental results on epitaxial stabilization of disordered Ni-Au and Cu-Ag alloys, immiscible in the bulk form, are explained in terms of destabilization of the phase separated state due to lattice mismatch between the substrate and constituents.Comment: RevTeX galley format, 16 pages, includes 9 EPS figures, to appear in Physical Review

The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths

We present the Planck Sky Model (PSM), a parametric model for the generation of all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model the cosmic microwave background, Galactic diffuse emission (synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H-II regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic Sunyaev-Zeldovich signals from clusters of galaxies. Each component is simulated by means of educated interpolations/extrapolations of data sets available at the time of the launch of the Planck mission, complemented by state-of-the-art models of the emission. Distinctive features of the simulations are: spatially varying spectral properties of synchrotron and dust; different spectral parameters for each point source; modeling of the clustering properties of extragalactic sources and of the power spectrum of fluctuations in the cosmic infrared background. The PSM enables the production of random realizations of the sky emission, constrained to match observational data within their uncertainties, and is implemented in a software package that is regularly updated with incoming information from observations. The model is expected to serve as a useful tool for optimizing planned microwave and sub-millimetre surveys and to test data processing and analysis pipelines. It is, in particular, used for the development and validation of data analysis pipelines within the planck collaboration. A version of the software that can be used for simulating the observations for a variety of experiments is made available on a dedicated website.Comment: 35 pages, 31 figure

The influence of social contagion within education: a motivational perspective

This article provides an overview of research on social contagion in the context of education. We highlight the importance of students' social interactions in school, considering contagion between peers and contagion from teachers to students, using a motivation perspective. The framework of contagion is introduced broadly, followed by a focused review on social contagion in school environments, both peer and teacher related. Then we introduce methodology for mapping behavior change to networks that are a direct representation of school cohorts. We argue that these different lines of research can be coherently interpreted from a motivation perspective, suggesting the critical role of motivation in social contagion, in the context of education. We highlight the limited amount of research on positive contagion effects and we call for further investigation into ways in which to increase the contagion of positive, academic behaviors. Finally, the neuroscience behind social contagion, both for the mechanisms and the interactions, is discussed