233 research outputs found
Évolution du système éducatif algérien et enjeux d’avenir
Le 5 juillet 1962, le gouvernement provisoire de la République algérienne proclame l’indépendance. La Constitution est adoptée en août 1963. Concernant l’éducation, mention est faite (article 18) que l’instruction est obligatoire (mais sans en préciser la durée), sans discrimination, notamment selon le sexe (article 12) et gratuite (article 10). L’arabe est la langue nationale et officielle de l’État (article 5), bien qu’à titre transitoire, la langue française puisse être utilisée (article 7..
An automatic pipeline for PET/MRI attenuation correction validation in the brain
PURPOSE: Challenges in PET/MRI quantitative accuracy for neurological uses arise from PET attenuation correction accuracy. We proposed and evaluated an automatic pipeline to assess the quantitative accuracy of four MRI-derived PET AC methods using analytically simulated PET brain lesions and ROIs as ground truth for PET activity.
METHODS: Our proposed pipeline, integrating a synthetic lesion insertion tool and the FreeSurfer neuroimaging framework, inserts simulated spherical and brain ROIs into PET projection space, reconstructing them via four PET MRAC techniques. Utilizing an 11-patient brain PET dataset, we compared the quantitative accuracy of four MRACs (DIXON, DIXONbone, UTE AC, and DL-DIXON) against the gold standard PET CTAC, evaluating MRAC to CTAC activity bias in spherical lesions and brain ROIs with and without background activity against original (lesion free) PET reconstructed images.
RESULTS: The proposed pipeline yielded accurate results for spherical lesions and brain ROIs, adhering to the MRAC to CTAC pattern of original brain PET images. Among the MRAC methods, DIXON AC exhibited the highest bias, followed by UTE, DIXONBone, and DL-DIXON showing the least. DIXON, DIXONbone, UTE, and DL-DIXON showed MRAC to CTAC biases of - 5.41%, - 1.85%, - 2.74%, and 0.08% respectively for ROIs inserted in background activity; - 7.02%, - 2.46%, - 3.56%, and - 0.05% for lesion ROIs without background; and - 6.82%, - 2.08%, - 2.29%, and 0.22% for the original brain PET images\u27 16 FreeSurfer brain ROIs.
CONCLUSION: The proposed pipeline delivers accurate results for synthetic spherical lesions and brain ROIs, with and without background activity consideration, enabling the evaluation of new attenuation correction approaches without utilizing measured PET emission data. Additionally, it offers a consistent method to generate realistic lesion ROIs, potentially applicable in assessing further PET correction techniques
Graded refraction index antireflection coatings based on silicon and titanium oxides
Thin films with a graded refraction index constituted from silicon and titanium
oxides were deposited by plasma enhanced chemical vapor deposition using electron
cyclotron resonance. A plasma of oxygen reacted with two precursors: the
tetraethoxysilane (TEOS) and the titanium isopropoxide (TIPT). The automatic
regulation of the precursor flows makes it possible to modify the chemical composition,
and consequently the optical index, through the deposited films. To control the thickness,
the refraction index and the growth kinetics, in situ spectroscopic ellipsometer was
adapted to the reactor. The analysis of ex situ ellipsometric spectra measured at the end
of each deposition allow to determine a refraction index profile and optical properties of
the inhomogeneous deposited films. Measurements of reflectivity carried out in the
ultraviolet-visible-near infrared range show that these films could be used as
antireflective coatings for silicon solar cells: 3.7 % weighted average reflectivity between
300 and 1100 nm and 48 % improvement of the photo-generated current were obtained
Characteristics UWB Planar Antenna with dual notched bands for WIMAX and WLAN
In this article, a novel design of ultra wideband monopole antenna with dual notched bands performance is proposed. The size of the UWB antenna is minimized to 20 -17.6mm2 , printed on FR4 substrate 1.5 mm thickness and loss tangent ta
Using MAS to detect retinal blood vessels
The segmentation of retinal vasculature by color fundus images analysis is crucial for several medical diagnostic systems, such as the diabetic retinopathy early diagnosis. Several interesting approaches have been done in this field but the obtained results need to be improved. We propose therefore a new approach based on an organization of agents. This multi-agent approach is preceded by a preprocessing phase in which the fundamental filter is an improved version of the Kirsch derivative. This first phase allows the construction of an environment where the agents are situated and interact. Then, edges detection emerged from agents’ interaction. With this study, competitive results as compared with those present in the literature were achieved and it seems that a very efficient system for the diabetic retinopathy diagnosis could be built using MAS mechanisms.Fundação para a Ciência e a Tecnologia (FCT
Reflection loss minimization for a ZnO/CdS/CuInSe₂ photovoltaic cell
A photovoltaic cell, based on copper and indium selenide (CuInSe₂) thin
layers, with a good efficiency can be achieved by simple, easy to implement and low cost
techniques. The high refractive index materials used as absorbers in photovoltaic cells
cause high reflection losses (about 30%). Thin CdS and ZnO films that are, respectively,
the buffer layer and the window of the cell have lower indices and are naturally suited to
antireflective applications. Also, a suitable choice of the film thickness leads to
minimization of reflection losses, resulting in a significant improvement of the
photovoltaic efficiency. The aim of this work is to provide easy solutions that reduce
reflection losses to less than 4% while respecting technological constraints
Образ міста у “Вступній новелі” та “Арабесках” М. Хвильового
Стаття присвячена аналізу образу міста у “Вступній новелі” та “Арабесках” М. Хвильового.
Досліджуються елементи “міського тексту” Харкова, присутні у творах. Образ міста, зображеного
у новелах, співвідноситься з містом концентричного й ексцентричного типу, містом-дівою, містом-
блудницею, містом-карнавалом, містом-ярмарком.
Ключові слова: образ міста, місто концентричного типу, місто ексцентричного типу,
місто-діва, місто-блудниця, місто-карнавал, “міський текст” Харкова.Стаття посвящается образу города в “Вступительной новелле” и “Арабесках” М. Хвылевого.
Исследуются элементы “городского текста” Харькова, присутствующие в произведениях. Образ
города, изображенного в новеллах соотносится с городом концентрического и эксцентрического
типа, городом-девой, городом-блудницей, городом-карнавалом.
Ключевые слова: образ города, город концентрического типа, город эксцентрического
типа, город-дева, город-блудница, город-карнавал, “городской текст” Харькова.The article is devoted to an image of a city in M. Hvylevogo’s “The introductory short story” and
“Arabesques”. Elements of Kharkovs “the city text” are investigated. The image of the city represented
in short stories corresponds with a city of concentric and eccentric type, a city-maiden, a city-loose
woman, a city-carnival.
Keywords: an image of a city, a city of concentric type, a city of eccentric type, a city-maiden, a
city-loose woman, a city-carnival, “the city text” of Kharkov
The role of a professor of physical and sports education in discovering and directing young talents in volleyball (Field study of some middle school of dar chioukh province ).
هدفت هذه الدراسة للتعرف على دور أستاذ التربية البدنية والرياضية في الكشف عن الموهوبين وتوجيههم إلى نوادي الكرة الطائرة في الطور المتوسط حيث أجريت الدراسة على تلاميذ المرحلة المتوسطة ببلدية دار الشيوخ ولاية الجلفة ،أما العينة فتكونت من 10 أساتذة و100 تلميذ واستعمل الباحث المنهج الوصفي المسحي وقد تم استعمال الاستبيان بالنسبة لعينة الأساتذة والتلاميذ متكون من ثلاث محاور كل محور يحتوي على مجموعة من الأسئلة أما الأساليب الإحصائية استخدمنا قانون النسب المئوية لتحليل النتائج في جميع الأسئلة بعد حساب تكررات كل منهما حيث تمثلت نتائج الدراسة في :أساتذة التربية البدنية والرياضية لا يقومون بالتوجيه للتلاميذ الموهوبين على الوجه المتمم . This study aimed to identify the role of a professor of physical education and sports in uncovering talented people and directing them to volleyball clubs in the intermediate stage, where the study was conducted on middle school students in the municipality of Dar chioukh , the state of Djelfa.As for the sample, it consisted of 10 teachers and 100 students, and the researcher used the descriptive survey approach, and the questionnaire was used for the sample of teachers and students It consists of three topics, each topic contains a group of questions. As for the statistical methods, we used the law of percentages to analyze the results in all questions after calculating the frequencies of each of them. The results of the study were: Physical education and sports teachers do not direct the talented students in a complementary wa
Characterisation and photocatalytic assessment of TiO2 nano-polymorphs: Influence of crystallite size and influence of thermal treatment on paint coatings and dye fading kinetics
Photoluminescence characterization of Al/Al₂O₃/InP MIS structures passivated by anodic oxidation
Metal-insulator-semiconductor (MIS) structures were produced by electron beam heating evaporation of Al₂O₃ on InP. Polyphosphate thin films with the thickness of 100 to 150 A were used to passivate the interface InP/Insulator. Photoluminescence spectra were obtained at low temperatures at the various stages of MIS-InP structure formation. At ambient temperature, photoluminescence topography made it possible to characterize the surface state after each technological stage. The interface degradation under the effect of repeated annealing is insignificant up to the temperatures close to 350 °C. Major radiative defects detected using photoluminescence spectrum with energies ranged from 0.95 to 1.15 eV were attributed to the impurity complexes of phosphorus vacancies, concentration of which is substantially reduced in the presence of
anodic oxide
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