Introduction to the Infrared Space Observatory (ISO)

The Infrared Space Observatory (ISO) is an astronomical satellite, which will operate at infrared wavelengths (2.5 to 200 microns) for a period of at least 18 months. Imaging, spectroscopic, photometric and polarimetric observations will be obtained by four scientific instruments in the focal plane of its 60-cm diameter, cryogenically-cooled telescope. Two-thirds of ISO's observing time will be available to the astronomical community. ISO is a fully approved and funded project of the European Space Agency (ESA) with a foreseen launch date of May 1993

Une description générale de la rupture dans les sols et son implication dans la stabilité des ouvrages hydrauliques

National audienceLa rupture des sols est classiquement décrite par le critère de Mohr-Coulomb correspondant à la condition limite de plasticité. Toutefois, les matériaux tels que les sols (présentant une règle d'écoulement non associée) peuvent être sujets à des modes de rupture pour des états de contrainte situés strictement à l'intérieur du critère de Mohr-Coulomb. Cela signifie que la vérification de la stabilité d'un ouvrage en sol s'appuyant uniquement sur un critère de rupture de type Mohr-Coulomb (soit sur la plastification du sol) ne permet pas, en général, de se prévenir de l'ensemble des modes de rupture pouvant se développer au sein du matériau constitutif. Dans cette communication, nous présentons un cadre unique permettant à la fois la description de la rupture plastique (survenant sur le critère de Mohr-Coulomb), et des ruptures se développant à l'intérieur du critère de Mohr-Coulomb. Nous indiquons comment détecter à l'aide du travail du second ordre les états de contrainte à partir desquels les ruptures sont susceptibles de se développer ; et nous donnons les conditions nécessaires et suffisantes (portant à la fois sur la direction de chargement et sur le mode de contrôle du volume de sol considéré) au développement effectif de ces ruptures. Enfin, l'implication de cette description généralisée de la rupture sur l'analyse de la stabilité des ouvrages hydrauliques en terre est abordée. L'ensemble de la discussion est appuyée sur des résultats d'essais de laboratoire et de simulations numériques

Macroscopic Quantum Tunnelling in Rotating Bose-Einstein Condensates

In this paper we investigate the macroscopic quantum tunnelling and the phase coherence property of the rotating Bose-Einstein condensates in both static and dynamic cases by using the mean field theory.Comment: 10 pages, 1 figure, submitted to Phys.Rev.

ISOCAM observations of the L1551 star formation region

The results of a deep mid-IR ISOCAM survey of the L1551 dark molecular cloud are presented. The aim of this survey is a search for new YSO (Young Stellar Object) candidates, using two broad-band filters centred at 6.7 and 14.3 micron. Although two regions close to the centre of L1551 had to be avoided due to saturation problems, 96 sources were detected in total (76 sources at 6.7 micron and 44 sources at 14.3 micron). Using the 24 sources detected in both filters, 14 were found to have intrinsic mid-IR excess at 14.3 micron and were therefore classified as YSO candidates. Using additional observations in B, V, I, J, H and K obtained from the ground, most candidates detected at these wavelengths were confirmed to have mid-IR excess at 6.7 micron as well, and three additional YSO candidates were found. Prior to this survey only three YSOs were known in the observed region (avoiding L1551 IRS5/NE and HL/XZ Tau). This survey reveals 15 new YSO candidates, although several of these are uncertain due to their extended nature either in the mid-IR or in the optical/near-IR observations. Two of the sources with mid-IR excess are previously known YSOs, one is a brown dwarf MHO 5 and the other is the well known T Tauri star HH30, consisting of an outflow and an optically thick disk seen edge on.Comment: 14 Pages, 8 Figure

ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster

We present the results of the first extensive mid-infrared (IR) imaging survey of the rho Ophiuchi embedded cluster, performed with the ISOCAM camera on board the ISO satellite. The main molecular cloud L1688, as well as L1689N and L1689S, have been completely surveyed for point sources at 6.7 and 14.3 micron. A total of 425 sources are detected including 16 Class I, 123 Class II, and 77 Class III young stellar objects (YSOs). Essentially all of the mid-IR sources coincide with near-IR sources, but a large proportion of them are recognized for the first time as YSOs. Our dual-wavelength survey allows us to identify essentially all the YSOs with IR excess in the embedded cluster down to Fnu ~ 10 - 15 mJy. It more than doubles the known population of Class II YSOs and represents the most complete census to date of newly formed stars in the rho Ophiuchi central region. The stellar luminosity function of the complete sample of Class II YSOs is derived with a good accuracy down to L= 0.03 Lsun. A modeling of this lumino- sity function, using available pre-main sequence tracks and plausible star for- mation histories, allows us to derive the mass distribution of the Class II YSOs which arguably reflects the IMF of the embedded cluster. We estimate that the IMF in rho Ophiuchi is well described by a two-component power law with a low- mass index of -0.35+/-0.25, a high-mass index of -1.7 (to be compared with the Salpeter value of -1.35), and a break occurring at M = 0.55+/-0.25 Msun. This IMF is flat with no evidence for a low-mass cutoff down to at least 0.06 Msun.Comment: A&A Document Class -- version 5.01, 27 pages, 10 figures v2: typos added including few changes in source numberin

Phenomenological interpretation of internal erosion in granular soils from a discrete fluid-solid numerical model

Internal erosion in granular soils may involve different steps: the detachment of solid particles from the granular skeleton under the action of water seepage; the transport of the detached particles carried with the water flow in the pore space; and eventually, for some erosion processes, such as suffusion, the possible reattachment of some transported particles to the solid skeleton of the soil, acting as a filter. The first part of this paper is devoted to the description and interpretation of the first step about the particle detachment. The analysis is mainly based on direct numerical simulations performed with a fully coupled discrete element-lattice Boltzmann method. Dynamics of the solid granular phase is represented thanks to the discrete element method in which each solid particle is explicitly described, whereas dynamics of the interstitial water flow is solved with the lattice Boltzmann method. Interactions between the solid phase and the fluid phase are handled at the particle scale avoiding the introduction in the model of some phenomenological constituents to deal with fluid-solid interactions. Numerical modellings of hole erosion can be interpreted similarly to laboratory hole erosion tests where the erosion rate is linearly related to the hydraulic shear stress. Further investigations from the numerical results suggest that the erosion rate for hole erosion in granular soil, can also be interpreted as a function of the water flow power according to a power law. The latter interpretation is applied to experimental data from suffusion tests on a cohesionless soil and glass bead mixtures. Here again, if change of erosion rate due to filtration is discarded, erosion rate is correctly described by the water seepage power according to a power law. Finally, a simple phenomenological model is suggested to describe the whole suffusion process, based on the previous results, to describe the particle detachment, and completed to take also into account the transport and filtration phases. Predictions of this model are compared with experimental results from suffusion tests on glass bead mixtures

‘Not in it for huge profits but because it’s right’: the contested moral economies of UK–India exports in health worker education and training

While the growth of global markets in health-related services may have significant consequences for healthcare provisioning and training, it has received relatively little attention from the social sciences. This article examines UK–India, and specifically England–India, exports in health worker education and training as one such global market, drawing on sociological scholarship on moral economies to understand how trading in this field is constructed and legitimated by the individuals and organisations involved, what tensions evolve, and what is at stake in them. We employ a qualitative mixed methods approach using publicly available materials on existing UK–India collaborations and primary data from interviews with key stakeholders in India and the UK, including government departments, arms-length bodies, NHS Trusts, trade associations and private providers. Our analysis illustrates the key discursive strategies used to legitimate engagement in these markets, and the complex and contested moral economies unfolding between and across these stakeholders and contexts. Not least, we demonstrate the conflicting moral sentiments and the boundary work required to realise commodification. Situating cross-border trade in health worker education and training in a moral economy framework thus illuminates the social context and moral worlds in which this evolving trade is embedded

Market making and the production of nurses for export. A case study of India-UK health worker migration

Background: High-income countries increasingly look to the international recruitment of health workers to address domestic shortages, especially from low-income and middle-income countries. We adapt conceptual frameworks from migration studies to examine the networked and commercialised nature of the Indian market for nurse migration to the UK. Methods: We draw on data from 27 expert interviews conducted with migration intermediaries, healthcare providers and policymakers in India and the UK. Findings: India–UK nurse migration occurs within a complex and evolving market encompassing ways to educate, train and recruit nursing candidates. For-profit actors shape the international orientation of nursing curricula, broker on-the-job training and offer language, exam and specialised clinical training. Rather than merely facilitate travel, these brokers produce both generic, emigratory nurses as well as more customised nurses ready to meet specific shortages in the UK. Discussion: The dialectic of producing emigratory and customised nurses is similar to that seen in the Post-Fordist manufacturing model characterised by flexible specialisation and a networked structure. As the commodity in this case are people attempting to improve their position in life, these markets require attention from health policy makers. Nurse production regimes based on international market opportunities are liable to change, subjecting nurses to the risk of having trained for a market that can no longer accommodate them. The commercial nature of activities further entrenches existing socioeconomic inequalities in the Indian nurse force. Negative repercussions for the source healthcare system can be anticipated as highly qualified, specialised nurses leave to work in healthcare systems abroad