A mixed-layer kaolinite/smectite (K/S) containing trace amounts of quartz, discrete kaolinite, goethite-hematite, and calcite was hydrothermally reacted with deionized water at 150°, 200°, and 250°C for 1 to 12 months. The starting K/S contained 50% smectite consisting of 15% low-charge and 35% high-charge layers. The X-ray powder diffraction and chemical analyses of the reacted products indicated a progressive reaction from high-charge to low-charge smectite as a function of time and temperature. The reaction reached completion after 4 months at 250°C, at which point high-charge smectite layers entirely reacted to low-charge smectite layers, the latter maintaining a constant proportion of about 90% for longer run durations. For long reaction times, discrete kaolinite totally reacted, whereas quartz showed only partial dissolution and iron oxides remained stable. Thus, the reaction of high-charge to low-charge smectite layers may be expressed as: high-charge smectite + kaolinite (both interstratified and discrete component) + quartz → low-charge smectite.

Under closed geochemical conditions, the weathering of a serpentinite rock composed of serpentine (70–85%) and magnesian chlorite (10–15%) associated with magnetite and chromite leads to the complete replacement of serpentine and chlorite by 2:1 layer silicates and produces new Fe oxides. The serpentine minerals crystallize under different habits issued from the serpentinization processes: mesh and hourglass pseudomorphic textures were formed from olivine, and thin-bladed pseudomorphic textures from pyroxene and amphibole crystals. Serpentine veins crosscut the whole rock with locally non-pseudomorphic interpenetrating and interlocking serpentines.

Specific weathering microsystem habits with specific clay mineral crystallizations originate from these different habits: a poorly aluminous saponite in thin-bladed textures, two Fe-rich montmorillonites in mesh and hourglass (MH) textures, and in veins (V) which differentiate on Al, Mg and Fe contents. Magnesian chlorites, isolated from serpentine by hand-picking under a stereomicroscope, are found to weather to trioctahedral vermiculite. Magnetite and chromite extracted from the bulk samples are replaced by newly formed Fe oxides, maghemite, goethite and hematite, which give way to specific Fe accumulation habits in the regolith zone of the weathering profile.

The early stages of amphibole weathering result in the crystallization of several clay mineral species: tri- and dioctahedral smectites, interstratified dioctahedral kaolinite-smectite (K-S), and halloysite. Each clay mineral crystallizes into specific microsites which develop from etch pits along specific crystallographic directions in the host amphibole. Two types of microsites are recognized according to their location in the amphibole crystal and their clay mineral crystallizations. The first type is a plane surface related to the (110) amphibole cleavages where saponite particles crystallize in a characteristic honeycomb texture. The second type is a ‘sawtooth’ (001) fracture surface generated by etch-pit coalescence where (1) platy K-S particles crystallize directly in contact with the amphibole at the top of ‘teeth’, (2) halloysite particles with tubular habits crystallize directly in contact with the amphibole on the side of the ‘teeth’, and/or on the K-S particles, and (3) montmorillonite crystallizes in the central part of the (001) fracture as a layer with honeycomb texture in contact with the K-S platelets located at the top of ‘teeth’. The microtextural relationships between the clay minerals and their host mineral suggest the following crystallization sequence: (1) saponite and montmorillonite crystallize first on the (110) and (001) surfaces, respectively; (2) as amphibole dissolution proceeds perpendicular to the (001) fracture planes, montmorillonites continue to form in the middle part of the widening fracture whereas K-S crystallizes on the ‘sawtooth’ termination; (3) in the last stage of weathering, tubular halloysite crystallizes on the side of the ‘teeth’, and/or on the K-S.

Bulk mineralogical and chemical properties of a weathering profile derived from serpentinite were studied using classical pedological methods (Munsell soil colors, particle-size distribution, density, cation exchange capacity, exchangeable bases, among others) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) results. Bulk clay fractions were characterized using X-ray diffraction, thermal analysis, electron microprobe, Mössbauer and infrared spectroscopies. Bulk geochemical mass-balance calculated from ICP-AES results shows leaching of both Mg and Si which reflects the early weathering of serpentine minerals. As a consequence, newly formed clay minerals are enriched with the least mobile elements, i.e. Fe and Al, producing dioctahedral smectites. These dioctahedral smectites are complex, heterogeneous and consist mainly of two populations. One population is an Fe-rich montmorillonite with little or no tetrahedral charge and Fe3+ as the dominant octahedral cation whereas the second population exhibits tetrahedral charge. Both populations occur as interstratified layers in the lower horizon of the weathering profile but show increasing segregation into well-defined end-members towards the surface horizons. Considering total Al and Fe contents, these clays differentiate into two chemical composition domains, Fe-rich clays in the lower profile and Al-rich clays towards the surface horizons.

In the absence of perfect reference standard, classical techniques result in biased diagnostic accuracy and prevalence estimates. By statistically defining the true disease status, latent class models (LCM) constitute a promising alternative. However, LCM is a complex method which relies on parametric assumptions, including usually a conditional independence between tests and might suffer from data sparseness. We carefully applied LCMs to assess new campylobacter infection detection tests for which bacteriological culture is an imperfect reference standard. Five diagnostic tests (culture, polymerase chain reaction and three immunoenzymatic tests) of campylobacter infection were collected in 623 patients from Bordeaux and Lyon Hospitals, France. Their diagnostic accuracy were estimated with standard and extended LCMs with a thorough examination of models goodness-of-fit. The model including a residual dependence specific to the immunoenzymatic tests best complied with LCM assumptions. Asymptotic results of goodness-of-fit statistics were substantially impaired by data sparseness and empirical distributions were preferred. Results confirmed moderate sensitivity of the culture and high performances of immunoenzymatic tests. LCMs can be used to estimate diagnostic tests accuracy in the absence of perfect reference standard. However, their implementation and assessment require specific attention due to data sparseness and limitations of existing software.

We assessed clinicians’ continuing professional development (CPD) needs at family practice teaching clinics in the province of Quebec. Our mixed methodology design comprised an environmental scan of training programs at four family medicine departments, an expert panel to determine priority clinical situations for senior care, a supervisors survey to assess their perceived CPD needs, and interviews to help understand the rationale behind their needs. From the environmental scan, the expert panel selected 13 priority situations. Key needs expressed by the 352 survey respondents (36% response rate) included behavioral and psychological symptoms of dementia, polypharmacy, depression, and cognitive disorders. Supervisors explained that these situations were sometimes complex to diagnose and manage because of psychosocial aspects, challenges of communicating with patients and families, and coordination of interprofessional teams. Supervisors also reported more CPD needs in long-term and home care, given the presence of caregivers and complexity of senior care in these settings.

We present new results of our wide-field redshift survey of galaxies in a 182 square degree region of the Shapley Supercluster (SSC) based on observations with the FLAIR-II spectrograph on the UK Schmidt Telescope (UKST). In this paper we present new measurements to give a total sample of redshifts for 710 bright (R ≤ 16.6) galaxies, of which 464 are members of the SSC (8000 < v < 18 000 km s–1). Our data reveal that the main plane of the SSC (v ≈ 14 500 km s–1) extends further than previously realised, filling the whole extent of our survey region of 10 degrees by 20 degrees on the sky (35 Mpc by 70 Mpc, for H0 = 75 km s–1 Mpc–1). There is also a significant structure associated with the slightly nearer Abell 3571 cluster complex (v ≈ 12 000 km s–1) with a caustic structure evident out to a radius of 6 Mpc. These galaxies seem to link two previously identified sheets of galaxies and establish a connection with a third one at V (V) = 15 000 km s–1 near RA = 13h. They also tend to fill the gap of galaxies between the foreground Hydra-Centaurus region and the more distant SSC. We calculate galaxy overdensities of 5.0 ± 0.1 over the 182 square degree region surveyed and 3.3 ± 0.1 in a 159 square degree region excluding rich clusters. Over the large region of our survey the inter-cluster galaxies make up 46 per cent of all galaxies in the SSC region and may contribute a similar amount of mass to the cluster galaxies.

We present new radial velocities for 306 bright (R < 16) galaxies in a 77 deg2 region of the Shapley supercluster, measured with the FLAIR-II spectrograph on the UK Schmidt Telescope. The galaxies we measured were uniformly distributed over the survey area, in contrast to previous samples which were concentrated in several rich Abell clusters. Most of the galaxies (230) were members of the Shapley supercluster: they trace out two previously unknown sheets of galaxies linking the Abell clusters of the supercluster. In a 44 deg2 area of the supercluster excluding the Abell clusters, these sheets alone represent an overdensity of a factor of 2·0 ± 0·2 compared to a uniform galaxy distribution. The supercluster is not flattened in the Declination direction as has been suggested in previous papers. Within our survey area the new galaxies contribute an additional 50% to the known contents of the Shapley supercluster, with a corresponding increase in its contribution to the motion of the Local Group.

We present results of our wide-field redshift survey of galaxies in a 285 square degree region of the Shapley Supercluster (SSC).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The photofission process has been recently considered for the production of neutron rich isotopes and the development of radioactive beams. The radioprotection hazard should be studied accordingly. A survey of the radiative electron energy loss theory is reported in order to estimate numerically the bremsstrahlung production of thick targets. The resulted bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are presented and compared with previous results. This study is focused on initial kinetic energies of the electron beam included in the range 30-60 MeV, suitable for the production of large photon yields able to induce the 238U fission. The source term for 50 MeV incident electrons is reported for radioprotection purposes.

La production de neutrons secondaires issus de l'interaction dun faisceau de particules avec une cible épaisse a été déterminée à plusieurs angles par la méthode des détecteurs à activation. Lescouples projectile-cible étudiés sont au nombre de trois : deutons (100 MeV/u) + 238U, deutons (100 MeV/u) + 9Be et 36Ar (95 MeV/u) + 12C. À 00 pour les cibles de Be et U, la mesure a aussiété faite avant et après des blocs de béton, ceci nous a permis d'évaluer les longueurs d'atténuation correspondantes en fonction de l'énergie. L'évolution du débit de dose de la cible d'uranium aété suivi durant plusieurs jours après la fin de l'irradiation.

A special class of scheduling problems is studied in this paper, named Hybrid Flowshop, n jobs have to be performedin a shop and each of them has the same routing (so this is a flowshop). A job consists in k different operations. A set of machines are able to perform each operation and thisset is called a stage. So when a job consists in two operations,there are two stages in the shop. After introducing the scheduling generalities, we define our preocupations and we propose a notationin order to identify precisely and rapidly a problem. Then a state of the art is proposed and presented in two parts. The first one is dedicated to the 2-stage hybrid flowshops and the second to thegeneral case of the k-stage. Then a summary puts to the fore that many problems remain unsolved.

Powder and ceramics of barium titanate prepared by the citric process were studied by x-ray photoelectron spectroscopy (XPS). Spectra of C1s, O1s, Ti2p, Ba3d, and Ba4d levels are analyzed in powder and ceramics immediately after the sintering step and after several months of exposure in the air. Ar-ion etching allowed one to characterize the material intrinsic carbon. The results are discussed in comparison with works previously published on oxide single crystals.

Amorphous silicon TFTs have been realized using several plasma-CVD systems which differ in the conception of the reactor: hot or cold walls, and from the frequency used: 400 kHz and 13.56 MHz. Silicon nitride has been used as insulator. Inverted and direct staggered structures with different channel dimensions (0.5 ≤ W/L ≥ 20) are compared. High performance TFTs with mobility from 0.5 to 0.7 cm2V−1s−1 for inverted and from 0.1 to 0.4 cm2V−1s−l for direct staggered TFTs have been optimized by a full study of the insulator semiconductor and source/drain contact properties.