A quantification of the glacial imprint on relief development in the French western Alps

International audienceThe morphology of the western Alps has been strongly influenced by Quaternary glaciations. On the basis of observations of glacial morphology in the Belledonne, Grandes Rousses, Taillefer and Pelvoux-Ecrins Massifs (south-eastern France), we reconstitute the glacial trimline and Equilibrium Line Altitude (ELA) during the most extensive glaciation (MEG). Our best estimate of the MEG ELA is 1800 ± 100m. Using digital elevation models, we compare our glacial reconstruction with the relief structure of nine major catchments draining the massifs. Modal elevations of the largest catchments occur at 2000–2500m and coincide with minima in plots of mean slope angles as a function of elevation. Modal elevations and slope minima occur between the modern and MEG ELAs, confirming a strong glacial imprint on relief. In order to quantify glacial valley carving in the massifs, we isolated high-elevation, low-relief surfaces that form rock shoulders adjacent to the glacial valleys from a Digital Elevation Model and constructed an interpolated surface passing through these. Subtracting the present-day topography from this surface allows us to quantify the maximum glacial valley depths. Maximum valley depths determined in this manner are typically > 1000m, with spatial maxima occurring around the location of the MEG ELA in most valleys. These numbers do not take into account glacial valley widening and local glacial overdeepenings. The also neglect, however, potential pre-glacial fluvial valley incision, which could account for 20–50% of the measured valley depths. In spite of these problems, inferred valley depths are reasonably well correlated with the mean reconstructed ice thickness, and constitute about half of the sub-ridgeline relief of the studied catchments. These results lead us to propose a significant Quaternary increase in the relief of the French western Alps, controlled by climate and associated with the initiation of alpine glaciations. For reasonable values of the effective elastic thickness of the lithosphere, the isostatic response to glacial valley carving reaches values of not, vert, similar 300m across the massifs. This number is insufficient to substantially offset topographic lowering due to regional denudation, and we conclude that the isostatic response to glacial valley carving has not increased peak elevations significantly

Vortex liquid correlations induced by in-plane field in underdoped Bi2Sr2CaCu2O8+d

By measuring the Josephson Plasma Resonance, we have probed the influence of an in-plane magnetic field on the pancake vortex correlations along the c-axis in heavily underdoped Bi2Sr2CaCu2O8+d (Tc = 72.4 +/- 0.6 K) single crystals both in the vortex liquid and in the vortex solid phase. Whereas the in-plane field enhances the interlayer phase coherence in the liquid state close to the melting line, it slightly depresses it in the solid state. This is interpreted as the result of an attractive force between pancake vortices and Josephson vortices, apparently also present in the vortex liquid state. The results unveil a boundary between a correlated vortex liquid in which pancakes adapt to Josephson vortices, and the usual homogeneous liquid.Comment: 2 pages, submitted to the Proceedings of M2S HTSC VIII Dresde

Vortex Solid-Liquid Transition in Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta} with a High Density of Strong Pins

The introduction of a large density of columnar defects in %underdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ crystals does not, at sufficiently low vortex densities, increase the irreversibility line beyond the first order transition (FOT) field of pristine crystals. At such low fields, the flux line wandering length $r_{w}$ behaves as in pristine %Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ crystals. Next, vortex positional correlations along the $c$--axis in the vortex Bose glass at fields above the FOT are smaller than in the low--field vortex solid. Third, the Bose-glass-to-vortex liquid transition is signaled by a rapid decrease in c-axis phase correlations. These observations are understood in terms of the ``discrete superconductor'' model.Comment: 4 pages, 4 figures Submitted to Phys. Rev. B Rapid Comm. 16-1-2004 Revised version 18-3-200

The magnetization of PrFeAsO0.60_{0.60}F$_{0.12} sueprconductor

The magnetization of the PrFeAsO$_{0.60}$F$_{0.12}$ polycrystalline sample has been measured as functions of temperature and magnetic field $(H)$. The observed total magnetization is the sum of a superconducting irreversible magnetization ($M_s$) and a paramagnetic magnetization ($M_p$). Analysis of dc susceptibility $\chi(T)$ in the normal state shows that the paramagnetic component of magnetization comes from the Pr$^{+3}$ magnetic moments. The intragrain critical current density $(J_L)$ derived from the magnetization measurement is large. The $J_L(H)$ curve displays a second peak which shifts towards the high-field region with decreasing temperature. In the low-field region, a plateau up to a field $H^*$ followed by a power law $H^{-5/8}$ behavior of $J_L(H)$ is the characteristic of the strong pinning. A vortex phase diagram for the present superconductor has been obtained from the magnetization and resistivity data.Comment: A revised version with modified title,8 pages, 7 figure

Role of pair-breaking and phase fluctuations in c-axis tunneling in underdoped Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta}

The Josephson Plasma Resonance is used to study the c-axis supercurrent in the superconducting state of underdoped Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ with varying degrees of controlled point-like disorder, introduced by high-energy electron irradiation. As disorder is increased, the Josephson Plasma frequency decreases proportionally to the critical temperature. The temperature dependence of the plasma frequency does not depend on the irradiation dose, and is in quantitative agreement with a model for quantum fluctuations of the superconducting phase in the CuO$_{2}$ layers.Comment: 2 pages, submitted to the Proceedings of M2S-HTSC VIII Dresde

Multimorbidity is common among young workers and related to increased work absenteeism and presenteeism: results from the population–based Raine Study cohort

Objectives This study aimed to determine the extent of both multimorbidity and work productivity loss among young adults with paid work and to analyze their association. Methods We included 604 participants from a follow-up of the Raine Study that comprised a cohort who were 22 years at the time (Gen2-22). Information on 36 health conditions, grouped into 10 condition categories, was collected through questionnaires and physical assessments (for body mass index only). Quarterly questionnaires about work productivity, including total absenteeism, sickness absenteeism, and total presenteeism, were distributed electronically over the subsequent 12 months. Descriptive statistics were used to determine the prevalence of health conditions, condition categories, multimorbidity, and work productivity. Zero-inflated negative binomial regression analyses were used to assess the association of multimorbidity with productivity loss. Results Multimorbidity prevalence was substantially higher in females (63%) compared to males (41%). Productivity loss increased as the number of condition categories increased. For example, total absenteeism was associated with an increase in the number of health condition categories in males [incidence rate ratio (IRR) 1.20, 95% confidence interval (CI) 1.05–1.36] and females (IRR 1.13, 95% CI 1.04–1.24). Similar results were found for sickness absenteeism and presenteeism. The highest burden of productivity loss was found for musculoskeletal disorders (42 444 hours/1000 workers/year), sleep problems (33 581 hours/1000 workers/year), mental and neurological conditions (15 650 hours/1000 workers/year), and ‘other’ medical conditions (22 519 hours/1000 workers/year). Conclusions Multimorbidity appears to be highly prevalent among young adults with paid work and is strongly related to work productivity loss. Therefore, young workers should be targeted in interventions aiming to reduce multimorbidity and its impact on work productivity