Thermal-mechanical fatigue crack growth in Inconel X-750

Thermal-mechanical fatigue crack growth (TMFCG) was studied in a gamma-gamma' nickel base superalloy Inconel X-750 under controlled load amplitude in the temperature range from 300 to 650 C. In-phase (T sub max at sigma sub max), out-of-phase (T sub min at sigma sub max), and isothermal tests at 650 C were performed on single-edge notch bars under fully reversed cyclic conditions. A dc electrical potential method was used to measure crack length. The electrical potential response obtained for each cycle of a given wave form and R value yields information on crack closure and crack extension per cycle. The macroscopic crack growth rates are reported as a function of delta k and the relative magnitude of the TMFCG are discussed in the light of the potential drop information and of the fractographic observations

Polycyclic aromatic hydrocarbons (PAHs) in the atmospheres of two French alpine valleys: sources and temporal patterns

International audienceAlpine valleys represent some of the most important crossroads for international heavy-duty traffic in Europe, but the full impact of this traffic on air quality is not known due to a lack of data concerning these complex systems. As part of the program "Pollution des Vallées Alpines" (POVA), we performed two sampling surveys of polycyclic aromatic hydrocarbons (PAHs) in two sensitive valleys: the Chamonix and Maurienne Valleys, between France and Italy. Sampling campaigns were performed during the summer of 2000 and the winter of 2001, with both periods taking place during the closure of the "Tunnel du Mont-Blanc". The first objective of this paper is to describe the relations between PAH concentrations, external parameters (sampling site localization, meteorological parameters, sources), and aerosol characteristics, including its carbonaceous fraction (OC and EC). The second objective is to study the capacity of PAH profiles to accurately distinguish the different emission sources. Temporal evolution of the relative concentration of an individual PAH (CHR) and the PAH groups BghiP+COR and BbF+BkF is studied in order to differentiate wood combustion, gasoline, and diesel emissions, respectively. The results show that the total particulate PAH concentrations were higher in the Chamonix valley during both seasons, despite the cessation of international traffic. Seasonal cycles, with higher concentrations in winter, are also stronger in this valley. During winter, particulate PAH concentration can reach very high levels (up to 155 ng.m-3) in this valley during cold anticyclonic periods. The examination of sources shows the impact during summer of heavy-duty traffic in the Maurienne valley and of gasoline vehicles in the Chamonix valley. During winter, Chamonix is characterized by the strong influence of wood combustion in residential fireplaces, even if the temporal evolution of specific PAH ratios are difficult to interpret. Information on sources given by PAH profiles can only be considered in qualitative terms

Sharp transition for single polarons in the one-dimensional Su-Schrieffer-Heeger model

We study a single polaron in the Su-Schrieffer-Heeger (SSH) model using four different techniques (three numerical and one analytical). Polarons show a smooth crossover from weak to strong coupling, as a function of the electron-phonon coupling strength $\lambda$, in all models where this coupling depends only on phonon momentum $q$. In the SSH model the coupling also depends on the electron momentum $k$; we find it has a sharp transition, at a critical coupling strength $\lambda_c$, between states with zero and nonzero momentum of the ground state. All other properties of the polaron are also singular at $\lambda = \lambda_c$, except the average number of phonons in the polaronic cloud. This result is representative of all polarons with coupling depending on $k$ and $q$, and will have important experimental consequences (eg., in ARPES and conductivity experiments)

The new control system of the SPS target sector

The SPS, the Super Proton Synchrotron at CERN, is an accelerator originally designed and commissioned in 1976 for protons. The control system of the SPS target stations, beam absorbers and other aperture limiting devices was developed in the seventies. It was mainly based on home made electronics and equipment dependent software. With time, this electronics has become obsolete, difficult to maintain in operation and not suitable for integration into a modern control system. In 1997, a project was set up to modernise the electronics and the related software. The new control system is largely based on standard industrial hardware and software components. SIEMENS Simatic S7-300 programmable logic controllers have been used as equipment controllers and connected through PROFIBUS to a Windows-NT front-end PC running the SIEMENS WinCC SCADA package which acts as local controller and remote access gateway. This fully industrial solution has been successfully integrated into the actual SPS accelerator control infrastructure and is open to other industrial communication protocols. The design, development and realisation of the selected solution have been outsourced to industry

L’outre-mer français et l’euro.

Le paysage institutionnel de l’outre-mer français a connu des évolutions significatives ces dernières années, tant en droit français qu’en droit européen. Ces évolutions ont un impact sur le régime monétaire et des paiements des territoires ultra-marins.outre-mer, euro, DOM, COM, RUP, PTOM, régime monétaire.

Proximal ischemia is a frequent cause of exercise-induced pain in patients with a normal ankle to brachial index at rest

BACKGROUND: Excluding a vascular origin of exercise-related pain is often difficult in clinical practice. Recent papers have underlined the frequent association of concurrent lumbar spine degenerative disease and peripheral arterial disease. Furthermore, even when suspected, isolated exercise-induced proximal ischemia is difficult to diagnose. Measurement of transcutaneous oxygen pressure (tcpO2) is an interesting and accurate method to differentiate proximal (buttock) from distal (calf) regional blood flow impairment (RBFI) during exercise. OBJECTIVES: We searched for isolated proximal-without-distal RBFI as a possible cause of claudication, in patients with borderline (ABI-b: 0.91 - 0.99) or normal (ABI-n: 1.00 to 1.40) ankle to brachial index at rest. STUDY DESIGN: Retrospective cohort design study. We analyzed patients referred to our laboratory with symptom limiting claudication and an ankle brachial index within normal limits. SETTING: University-based exercise-investigation center. METHODS: Over a 12-year period, we identified 463 patients referred to our laboratory that had their lowest resting ABI between 0.90 and 1.40. The tcpO2 on chest, buttocks, and calves were recorded during treadmill walking tests (3.2 km/h, 10% slope) in 220 ABI-b and 243 ABI-n unique consecutive patients complaining of limiting claudication (each patient\u27s ABI was the lowest of the 2 legs). Limiting claudication was defined as the reported inability to walk 1 kilometer without stopping. A DROP index (limb tcpO2-changes minus chest tcpO2-changes from rest) below -15 mmHg was used to indicate a positive result (i.e. exercise-induced RBFI). RESULTS: Treadmill exercise showed evidence for proximal or distal RBFI, of at least one side, in 128 out of 220 patients (58.2%) and in 86 out of 243 (35.4%) patients with ABI-b and ABI-n, respectively. Isolated proximal-without-distal RBFI was found in 32 out of the 128 (25.0 %) positive tests in ABI-b and 32 out of the 86 (37.2%) positive tests in ABI-n patients. LIMITATIONS: Study limitations include the absence of systematic follow-up of diagnosed patients and absence of systematic search for cardio-respiratory co-morbid conditions. CONCLUSION: Isolated proximal-without distal RBFI is found in approximately one out of 7 patients complaining of symptom limiting claudication with a borderline or normal resting ABI. Exercise-tcpO2 may help to discriminate patients with arterial claudication that could benefit from invasive vascular investigations and procedures

Chemical solver to compute molecule and grain abundances and non-ideal MHD resistivities in prestellar core collapse calculations

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.We develop a detailed chemical network relevant to the conditions characteristic of prestellar core collapse. We solve the system of time-dependent differential equations to calculate the equilibrium abundances of molecules and dust grains, with a size distribution given by size-bins for these latter. These abundances are used to compute the different non-ideal magneto-hydrodynamics resistivities (ambipolar, Ohmic and Hall), needed to carry out simulations of protostellar collapse. For the first time in this context, we take into account the evaporation of the grains, the thermal ionisation of Potassium, Sodium and Hydrogen at high temperature, and the thermionic emission of grains in the chemical network, and we explore the impact of various cosmic ray ionisation rates. All these processes significantly affect the non-ideal magneto-hydrodynamics resistivities, which will modify the dynamics of the collapse. Ambipolar diffusion and Hall effect dominate at low densities, up to n_H = 10^12 cm^-3, after which Ohmic diffusion takes over. We find that the time-scale needed to reach chemical equilibrium is always shorter than the typical dynamical (free fall) one. This allows us to build a large, multi-dimensional multi-species equilibrium abundance table over a large temperature, density and ionisation rate ranges. This table, which we make accessible to the community, is used during first and second prestellar core collapse calculations to compute the non-ideal magneto-hydrodynamics resistivities, yielding a consistent dynamical-chemical description of this process

Estimation of running capacity can likely be removed from questionnaires estimating walking impairment in patients with claudication

OBJECTIVE: The Estimating Ambulation Capacity by History-Questionnaire (EACH-Q) and the Walking Impairment Questionnaire (WIQ) are used to estimate maximal walking distance (MWD). The EACH-Q and WIQ included 4 and 14 items respectively, among which one item dealing with running capacity. We hypothesised that this item was of little interest in patients with claudication. DESIGN: The WIQ and EACH-Q were self-completed and corrected before a constant load (3.2 km h(-1); 10% slope) treadmill tests, maximised to 15 min. PATIENTS: 371 patients (298 males/73 females, 62.9 +/- 11.2 years). METHODS: The number of errors (duplicate, absent or paradoxical answers to one item) and correlation of questionnaire scores with MWD on treadmill were calculated, before and after skipping the answer to the running item. RESULTS: The proportion of questionnaires with errors was 27% with the EACH-Q and 48% with the WIQ. Two-hundred and twenty-one (59.6%) and 245 (66%) out of 371 patients reported to be unable to run, for the EACH-Q and WIQ, respectively. The rate of errors was reduced by 15% for the EACH-Q (p < 0.05) when skipping the running item for scoring. The correlation coefficients between the MWD and the questionnaire scores were 0.449 and 0.485 for the EACH-Q and were 0.571 and 0.572 for the WIQ, before and after skipping the running item, respectively. CONCLUSION: Most of our patients reported to be unable to run and skipping the running item reduce the rate of errors in self-completing the questionnaires without impairing the correlation of questionnaire scores with treadmill results. It is likely that the running item could be removed from the WIQ and EACH-Q questionnaires

Quantification of Dendritic Cells and Osteoclasts in the Bone Marrow of Patients with Monoclonal Gammopathy

The purpose of this study was to find histological clues for reliable differentiation between monoclonal gammopathy of undetermined significance (MGUS) and myeloma when clinical parameters are controversial. Differential appearance of dendritic cells and osteoclasts, two cell types developing from the monocytic lineage upon distinct cytokine activation profile, might be a useful approach. Bone and bone-marrow biopsies performed in 105 patients were studied using histomorphometry after identification of osteoclasts (by histochemical identification of tartrate resistant acid phosphatase) and dendritic cells (by immunohistochemical detection of the S-100 protein). Patients were classified by the World Health Organization criteria but histopathological criteria were more adapted to identify MGUS (53 cases), myeloma (46), B-cell lymphoma (six) since six myeloma were not correctly classified. Histomorphometry was compared to 15 control cases. The number of marrow dendritic cell was significantly increased with B-cell lymphoma >MGUS >myeloma > controls. Dendritic cell were often mixed with lymphoma cells. Myeloma had increased bone resorption with a high osteoclast number and moderate increase in dendritic cells. B-cell lymphomas had a considerable increase in dendritic cell but presented mononucleated osteoclasts. These findings can help in the classification of MGUS in the early stages of the disease and could help to propose preventive treatments