Growth and structure of ultrathin alumina films on the (1 1 0) surface of γ-Al4Cu9 complex metallic alloy.

The first stages of oxidation of the (1 1 0) surface of a γ-Al(4)Cu(9) complex metallic alloy were investigated by combining x-ray photoemission spectroscopy, low energy electron diffraction and scanning tunnel microscopy studies. Oxidation at room temperature in the 2 × 10(-8) to 2 × 10(-7) mbar oxygen pressure range occurs in two steps: a fast regime is followed by a much slower one, leading to the formation of a thin aluminium oxide film showing no long range order. Cu-O bonds are never observed, due to fast oxygen induced aluminium segregation. The low value of the estimated activation energy for aluminium diffusion (0.65 ± 0.12 eV at(-1)) was ascribed to the presence of two vacancies in the γ-Al(4)Cu(9) structure. Annealing at 925 K the oxide film formed at room temperature leads to the formation of small crystallized domains with a sixton structure similar to structures reported in the literature following the oxidation of Cu-9% Al(1 1 1), NiAl (1 1 0) and FeAl(1 1 0) surfaces as well as ultrathin Al films deposited onto Cu(1 1 1) or Ni(1 1 1) surfaces. Two contributions were observed in the O1s peaks, which have been ascribed to loosely bound oxygen species and oxygen belonging to the sixton structure respectively.

Accurate determination of the scattering length of metastable helium atoms using dark resonances between atoms and exotic molecules.

We present a new measurement of the s-wave scattering length a of spin-polarized helium atoms in the 2(3)S1 metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy E(nu)=14= -91.35+/- 0.06 MHz of the least-bound state nu = 14 in the interaction potential of the two atoms. We deduce a value of a=7.512+/-0.005 nm, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of 1 micros.

Procedural memory in recent-onset Parkinson's disease.

Parkinson's disease is accompanied by cognitive disorders which may affect procedural memory. Procedural memory uses a specific knowledge resource that expresses itself through pre-established acting procedures. The aim of this study was to better define the characteristics of procedural memory, first of all, by trying to determine the level of involvement of that memory in the acquisition process (during learning and/or during procedure maintenance), then by specifying the effect of the type of resource involved (verbal or motor). To achieve this, we compared the mnestic performances of 20 recent-onset parkinsonian patients with those of 20 healthy controls, using two memory tasks with a fixed rule (poetry, visuomotor tracking). Result analysis revealed that parkinsonian patients had more difficulty than controls in learning the two rules, regardless of the material involved. Their deficiencies were often associated with an impairment of executive functions, and the procedural memory problems described in parkinsonian patients are linked to the involvement of these resources in the various tasks.

[Intravascular malignant B-cell lymphomatosis with renal glomerular involvement: a case]. / Lymphomatose maligne intravasculaire de type B avec atteinte rénale glomérulaire: une observation.

We report a case of intravascular malignant lymphomatosis observed in a 71 year-old male and characterised by the presence of a proteinuria in relation to the specific intraglomerular localisation. This malignant lymphoma, usually of the B phenotype, is rare and affects predominantly the central nervous system and the skin. Neoplastic cells home selectively to endothelium. Histological renal infiltration is frequent but a glomerular localisation, with proteinuria, is rare. The mechanism whereby lymphocytes home to endothelium cells is unclear but it could be related to the expression of lymphocyte-endothelium adhesion molecules. When present the nephrotic syndrome is associated with minimal change disease.

Effect of normal aging and of Alzheimer's disease on, episodic memory.

Performances of 12 patients with Alzheimer's disease (AD), 15 healthy elderly subjects and 20 young healthy volunteers were compared on two episodic memory tests. The first, a learning test of semantically related words, enabled an assessment of the effect of semantic relationships on word learning by controlling the encoding and retrieval processes. The second, a dual coding test, is about the assessment of automatic processes operating during drawings encoding. The results obtained demonstrated quantitative and qualitative differences between the population. Manifestations of episodic memory deficit in AD patients were shown not only by lower performance scores than in elderly controls, but also by the lack of any effect of semantic cues and the production of a large number of extra-list intrusions. Automatic processes underlying dual coding appear to be spared in AD, although more time is needed to process information than in young or elderly subjects. These findings confirm former data and emphasize the preservation of certain memory processes (dual coding) in AD which could be used in future therapeutic approaches.

Management and outcomes of 65 quadruplet pregnancies: sixteen years' experience in France.

OBJECTIVE: Data on the prognosis and management of multifetal pregnancies are of vital importance, particularly when the option of selective termination is considered. The present study details the obstetric management, neonatal outcome, and follow-up data of 65 quadruplet pregnancies in France. METHODS: To conduct the study, a questionnaire was sent to families registered with the National Association Helping Parents of Multiple Births (Association National d'Entraide des Parents de Naissance Multiples, A.N.E.P.N.M.). RESULTS: Of 116 questionnaires sent to families of quadruplets born between 1972 and 1988, 65 were received. Of these pregnancies, 58 were obtained with ovulation induction agents, 2 with IVF (in vitro fertilization) and GIFT (gamete intrafallopian transfer) and 5 were spontaneous. Diagnosis was made prior to 13 weeks gestation in 87.2% of cases. Most mothers were hospitalized prior to delivery--mean duration of 47 days. The mean gestational age at delivery was 31.2 +/- 3 weeks with a prematurity rate of 97%. Cesarean sections were performed in 51 cases and vaginal deliveries in 14. Neonatal and perinatal mortality rates were 68 and 104 per 1000, respectively. Birthweights of quadruplets ranged from 760 to 2455 g with a mean of 1615 g. CONCLUSION: Management of quadruplet pregnancies in France consists of early diagnosis, echographical and clinical monitoring, early reduction of maternal activity and cesarean deliveries. Our management of such pregnancies is of high quality as reflected by our obstetrical results. Lack of adequate management, as perceived by families of quadruplets, exists at two levels; a psychological (lack of psychological support) and a financial (lack of specific help).