Невелика надширокосмугова кругла патч-антена з режекторною смугою

У роботі ми пропонуємо розробити круглу мікросмугову патч-антену, надруковану на FR4- епоксидній діелектричній підкладці. Розроблена антена зможе застосовуватися для UWB (надширокосмугових) додатків. Федеральна комісія зв'язку (FCC) схвалила використання частотного спектру від 3,1 до 10,6 ГГц для UWB додатків. Запропонована антена має широкий діапазон частот пропускання, який включає смугу частот 3,85-12,38 ГГц, за винятком режекторної смуги 5,1-6 ГГц, що є основною характеристикою представленої антени. Ця особливість дозволяє уникнути втручання в додатки, які працюють у цьому діапазоні, таких як WLAN, IEEE 802.11a та HIPERLAN/2. Окрім цих характеристик, розроблена антена має просту структуру та невеликі розміри 24x14x0.8 мм3. Основні робочі параметри антени, такі як VSWR, діаграма випромінювання, ефективність випромінювання та групова затримка, моделюються за допомогою електромагнітних симуляторів HFFS та CST. Зміна групової затримки антени в смузі частот від 3,85 до 12,38 ГГц є майже постійною на рівні приблизно 1,25 нс і представляє невеликі коливання, за винятком режекторної смуги 5,1-5,8 ГГц, групова затримка якої падає з 1,5 нс до – 2 нс. Ці особливості роблять запропоновану антену кращим пристроєм для UWB додатків.In this paper, we propose to design a circular microstrip patch antenna printed on FR4-epoxy dielectric substrate. The designed antenna will be able to operate for UWB (ultra-wideband) applications. The Federal Communication Commission (FCC) has approved the use of the frequency spectrum from 3.1 to 10.6 GHz for UWB applications. The proposed antenna has a large bandwidth, which covers the frequency band of 3.85-12.38 GHz except the notch band of 5.1-6 GHz, which is the main characteristic of the presented antenna. This feature allows to avoid interferences with applications operating at this band such as WLAN, IEEE 802.11a, and HIPERLAN/2. Besides these characteristics, the designed antenna has a simple structure and small sizes of 24x14x0.8 mm3. The principal operating parameters of the antenna like VSWR, radiation pattern, radiation efficiency, and group delay are simulated using both HFFS and CST electromagnetic simulators. The variation of the group delay of the antenna in the frequency band from 3.85 to 12.38 GHz is almost constant at around 1.25 ns and presents small fluctuations, except in the vicinity of the 5.1-5.8 GHz notch band whose group delay drops from 1.5 ns to – 2 ns. These features make the proposed antenna a better device for UWB applications

Atypical Celiac Disease: From Recognizing to Managing

The nonclassic clinical presentation of celiac disease (CD) becomes increasingly common in physician’s daily practice, which requires an awareness of its many clinical faces with atypical, silent, and latent forms. Besides the common genetic background (HLA DQ2/DQ8) of the disease, other non-HLA genes are now notably reported with a probable association to atypical forms. The availability of high-sensitive and specific serologic tests such as antitissue transglutuminase, antiendomysium, and more recent antideamidated, gliadin peptide antibodies permits to efficiently uncover a large portion of the submerged CD iceberg, including individuals having conditions associated with a high risk of developing CD (type 1 diabetes, autoimmune diseases, Down syndrome, family history of CD, etc.), biologic abnormalities (iron deficiency anemia, abnormal transaminase levels, etc.), and extraintestinal symptoms (short stature, neuropsychiatric disorders, alopecia, dental enamel hypoplasia, recurrent aphtous stomatitis, etc.). Despite the therapeutic alternatives currently in developing, the strict adherence to a GFD remains the only effective and safe therapy for CD

Clinical and immunological status of a newly diagnosed HIV positive population, in Marrakech, Morocco

Objective: To evaluate the clinical and the immune status of newly HIV diagnosed patients, in Marrakech city and its neighboring area, in Morocco. Methods: We performed a retrospective study on 235 patients who have been previously confirmed for HIV infection, and underwent a CD4 T cells using flow cytometry (FacsCount, Becton Dickinson®). Results: The mean age of patients was 34,3 ± 8,4 years (range: 14-55), with a male predominance (sex-ratio M/F=1.4). On basis of clinical data of the patients, 62% (n=146) of them were categorized as "category C", 18.4% (n=43) as "category B", and 19.6% (n=46) as "category A" according to CDC (Center for Disease Control) HIV classification. Among all of them, 60.4% (n=142) had less than 200 CD4T cells, 26% (n=61) had between 200 and 499 CD4T cells, and only 13.6% (n=32) showed a number of CD4T cells less or equal to 500/mm3. Conclusion: The results of this study reflect a significant delay in the diagnosis of HIV infected patients. Therefore, this delay may compromise timely management of HIV infected individuals and enhances propagation of the epidemic in our country. These data confirm the need for intensifying prevention efforts among high-risk population. Moreover, continuing education in HIV/AIDS among healthcare providers should be reinforced