637 research outputs found
Structural investigation of (111) oriented (BiFeO3)(1-x){\Lambda}/(LaFeO3)x{\Lambda} superlattices by X-ray diffraction and Raman spectroscopy
(BiFeO3)(1-x){\Lambda}/(LaFeO3)x{\Lambda} superlattices (SLs) with varying x
have been grown by pulsed laser deposition on (111) oriented SrTiO3 substrates.
In order to obtain good epitaxy and flat samples a conducting SrRuO3 buffer has
been deposited prior to the superlattices to screen the polar mismatch for such
(111) SrTiO3 orientation. X-ray diffraction reciprocal space mapping on
different family of planes were collected and evidenced a room temperature
structural change at x=0.5 from a rhombohedral/monoclinic structure for rich
BiFeO3 to an orthorhombic symmetry for rich LaFeO3. This symmetry change has
been confirmed by Raman spectroscopy and demonstrates the different phase
stability compared to similar SLs grown on (100) SrTiO3. The strongly
anisotropic strain and oxygen octahedral rotation/tilt system compatibility at
the interfaces probably explain the orientation dependence of the phase
stability in such superlattices.Comment: 17 pages, 3 figure
A minimal HIV-AIDS infection model with general incidence rate and application to Morocco data
We study the global dynamics of a SICA infection model with general incidence
rate. The proposed model is calibrated with cumulative cases of infection by
HIV-AIDS in Morocco from 1986 to 2015. We first prove that our model is
biologically and mathematically well-posed. Stability analysis of different
steady states is performed and threshold parameters are identified where the
model exhibits clearance of infection or maintenance of a chronic infection.
Furthermore, we examine the robustness of the model to some parameter values by
examining the sensitivity of the basic reproduction number. Finally, using
numerical simulations with real data from Morocco, we show that the model
predicts well such reality.Comment: This is a preprint of a paper whose final and definite form is with
'Statistics Opt. Inform. Comput.', Vol. 7, No 2 (2019). See
[http://www.IAPress.org]. Submitted 16/Sept/2018; Revised 10 & 15/Dec/2018;
Accepted 15/Dec/201
Possibilité de lutte préventive contre Phoracantha semipunctata L. par la sélection d'espèces d'eucalyptus
Phoracantha semipunctata est un coléoptère xylophage qui s'attaque à des arbres en déséquilibre physiologique. Cette étude tente d'évaluer la résistance à l'égard de ce coléoptère par le taux de survie de certaines espèces plantées dans les différentes stations au Maroc
Hydrochemical characterization of groundwater in the Nekor basin located in the North-East of the Rif of Morocco
 In order to evaluate the physicochemical quality of the groundwater of the Nekor watershed (central Rif area in Morocco) and to explain the origin of the mineralization of these waters, we have analyzed the major elements and traces in water samples taken from 17 wells distributed along the basin. This study showed that the samples of water are very charged with a very important mineralization (≥ 1500 mg / l). The Piper diagram allowed us to define dominant Ca-SO4 or Mg-SO4 hydrochemical facies in upstream of the basin. In downstream of the basin Na-SO4 or Na-Cl is the dominant facies. The analyzes of the trace elements show very high levels of manganese, aluminum and iron with contents exceeding those set by the WHO recommendations.The geochemical study shows that the water-rock interaction is predominant in the aquifer. The water saturation indices indicate that these waters are supersaturated in carbonate minerals.The Principal Component Analysis (PCA) and the analysis of the reports of the major elements allowed us the classification of the waters and the determination of the correlation between the various parameters. Two major phenomena in the acquisition of mineralization of water have been put in evidence. The main phenomenon is the dissolution of the rock by the contact water rock due to the important residence time in the aquifer. The second phenomenon is associated to the supply of nutrients and therefore with the exchange and recharge of the aquifer. The use of hierarchical cluster analysis (HCA) technique revealed three homogeneous groups.
Nanomechanical properties of nanoconfined polystyrene nanoparticles in nanoblends
The role of nanoconfinement on the glass transition temperature (Tg) of polymers has been extensively studied in the thin film geometry. This work looks at the Tg of nanoconfined polystyrene in spherical nanoparticles (27- 200 nm), individually dispersed in crosslinked polybuthylmethacrylate matrices. A reduction of Tg compared to the bulk was observed in PS nanospheres via neutron scattering-mechanical tests and was found to decrease with decreasing diameter for D< 50nm. The general trend of Tg depression in nanospheres was found to be similar to the results on thin film geometry
Dysphagia caused by a lateral medullary infarction syndrome (Wallenberg’s syndrome)
A 68-year-old man was referred to our hospital for a dysphagia evolving for 10 days. Clinical examination had found neurological signs ascontralateral Horner’s syndrome, ipsilateral palatal paresis, gait ataxia and hoarseness. Video-fluoroscopy showed a lack of passage of contrastmedium to the distal esophagus. Esogastroduodenoscopy was normal. The cranial MRI had shown an acute ischemic stroke in the left lateral medullar region and the diagnosis of Wallenberg syndrome (WS) was established. WS remains an unknown cause of dysphagia in the clinical practice of the gastroenterologist.Key words: Dysphagia, lateral medullary infarction, Wallenberg’s syndrome, deglutitio
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