Klein tunneling through triple barrier in AB bilayer graphene

We investigate the transport properties of charge carriers in AB bilayer graphene through a triple electrostatic barrier. We calculate the transmission and reflection using the continuity conditions at the interfaces of the triple barrier together with the transfer matrix method. First, we consider the case where the energy is less than the interlayer coupling $\gamma_1$ and show that, at normal incidence, transmission is completely suppressed in the gap for a large barrier width while it appears in the gap for a small barrier width. For energies greater than $\gamma_1$, we show that in the absence of an interlayer potential difference, transmission is less than that of a single barrier, but in its presence, transmission in the gap region is suppressed, as opposed to a double barrier. It is found that one, two, or three gaps can be created depending on the number of interlayer potential differences applied. Resonance in the $T_-^+$ transmission channel is observed that is not seen in the single and double barrier cases. Finally, we compute the conductance and show that the number of peaks is greater than the double barrier case.Comment: 8 pages, 7 figure

FEASIBILITY STUDY FOR PRODUCTION OF IODINE-131 USING DIOXIDE OF TELLURIUM-130

Objective: Currently, nuclear medicine is becoming increasingly important, through the discovery of several medical radioisotopes, which are used in diagnosis, treatment, and medical imaging. Among the most important radionuclide which is commonly used is iodine-131, with a half-life of 8.02 d. Iodine-131 is one of the mainly essential elements in nuclear medicine. Since their first use, several studies have been conducted to meet the world need of hospital specialists in nuclear medicine. The purpose of this study was to participate in a lawsuit about the feasibility of producing 131I.Methods: using neutron activation of the dioxide of tellurium (TeO2) under a neutron flux which varies between 5 1011 and 1013 n/cm²s for 4, 6 and 8 hours** per irradiation cycle during 5 d, and used the Fortron90 Code to calculate the activity of iodine-131.Results: The result of the activity of iodine-131 found about 4,634 Curie with an irradiation of 4 hours** per day and 9.381 Curie with an activation of 8 hours** per day.Conclusion: Production of iodine-131 can be very effective if an acceptable capsule is used for different masses of tellurium and a neutron flux in a nuclear reactor

Should We Do Bilateral Internal Mammary Artery Grafting in Diabetic Patients?

Nowadays, potential advantages of BIMA grafting are recognized overall in terms of long-term survival1 and by not increasing operative morbidity. One of the major restrictions for extending the use of BIMA grafting is the current impossibility of generalizing the procedure to higher risk patients. These results tend to confirm recent results that promote the use of BIMA grafting in every kind of patients and consequently to confirm the generalization of the procedure, without being afraid of sternal complications. The absence of deep sternal wound infection in our study shows that there is no contraindication of BITA grafting among diabetic patients

ICT Integration into Chemistry-Physics Classes In Middle Schools Through A Participatory Pilot Project Approach

AbstractInformation and Communication Technology (ICT) based education was examined, through an integrated project, to experimentally determine how such technology could influence the motivation and performance of students in science (Chemistry-Physics, Mathematics, and Life-Earth sciences) in Morocco. The experiment was deliberately run at middle school level (age 12-14) as it constitutes the best stage in student life to influence their choice for the field of study. Two schools were selected based on their location and environment; one in a semi-rural area of Ifrane, and the other in the large city of Fes. The present study focuses more on the physical sciences (Chemistry-Physics), as they are taught together by the same teacher and represent a structural template of what was carried out within the framework of the pilot project.The project was the first of its kind in Morocco since it permitted decent usage of ICT in classroom sittings and allowed integral participation of middle school teachers in the elaboration of ICT pedagogical teaching resources using Arabic as teaching language. Control (standard) and experimental (ICT-based) classes were both taught by the same teachers and all the experiments were carried out in close collaboration between the authors and the teachers, with assistance from ICT engineers and technicians.Quantitative evaluation of the experimental data based on general balanced 3-stage nested design, together with qualitative assessment show a positive impact on the performance and motivation of students as well as their teachers.The project established successful practice guidelines and has set a promising roadmap for extending it at a larger scale to the rest of the country.As expected, this project encountered obstacles and limitations. Lessons learnt as well as suggestions are presented in this paper

A New Design of a CPW-Fed Dual-Band Monopole Antenna for RFID Readers

This paper comes with a new dual-band planar monopole antenna fed by Coplanar Waveguide (CPW) line designed for RFID readers and it operates at 2.45 GHz, 5.80 GHz. This antenna is designed with reasonable gain, low profile and low cost production. The designed antenna based on theoretical equations is simulated and validated by using ADS from Agilent technologies and CST Microwave Studio electromagnetic solvers. A parametric study of the proposed antenna has been carried out by optimizing some critical parameters. The antenna has a total area of 35×38 mm2 and mounted on an FR4 substrate with dielectric permittivity constant 4.4 and thickness of 1.6 mm and loss tangent 0.025. The comparison between simulation and measurement results permits to validate the final achieved antenna structure in the desired RFID frequencies bands. Details of the proposed antenna design and both simulated and experimental results are described and discusse

Comparative study of ochratoxin a exposure through the intake of cereal products in two climatic moroccan regions

The present study aims to compare ochratoxin A (OTA) exposure through the intake of three cereal derivative products (bread, pasta and semolina) in two different Moroccan climatic regions (littoral and continental). OTA weekly intakes from cereal products were calculated using a deterministic approach for each region. Results showed a statistically significant difference (p < 0.05) of OTA exposure between the two regions. Indeed, the median OTA exposure was estimated at 48.97 ng/kg b.w./week in the littoral region, while it was estimated at 6.36 ng/kg b.w./week in the continental region. The probabilistic approach showed that, due to uncertainties, the 95th percentile of weekly OTA exposure associated with the three cereal products ranged from 66.18 to 137.79 (95% CI) with a median of 97.44 ng/kg body weight (b.w.)/week. Compared to the threshold of 100 ng/kg b.w./week, 95% of the cumulative distributions predicted an exceedance frequency between 0.42 and 17.30% (95% CI), with an exceedance frequency median of 4.43%. Results showed that cereal derivatives constitute an important vector of OTA exposure and cause a significant exceedance of toxicological reference value among large consumers in the littoral region, which suggests the urgency of reconsidering the maximum regulatory limit (MRL) set for OTA (3 µg/kg) in cereal derivatives by Moroccan authorities.info:eu-repo/semantics/publishedVersio

A New Compact CPW-Fed Dual-Band Uniplanar Antenna for RFID Applications

In this paper a new dual-band uniplanar monopole antenna fed by Coplanar Waveguide (CPW) line is proposed for Radio Frequency Identification (RFID) applications. The antenna structure includes a CPW fed line and the dual-band operation is achieved from the G-shaped folded antenna. The antenna parameters have been investigated and optimized by using CST Microwave Studio. To validate the CST Microwave Studio results before the antenna achievement, we have conducted another study by using ADS. The final circuit was achieved, measured and validated. Experimental results show that the proposed antenna with compact size of 30*45 mm2 is simple in design and compact in size. It exhibits broadband impedance matching, consistent omnidirectional radiation patterns and appropriate gain characteristics suitable for the microwave RFID applicartions

Automated brain tumour identification using magnetic resonance imaging:a systematic review and meta-analysis

BACKGROUND: Automated brain tumor identification facilitates diagnosis and treatment planning. We evaluate the performance of traditional machine learning (TML) and deep learning (DL) in brain tumor detection and segmentation, using MRI. METHODS: A systematic literature search from January 2000 to May 8, 2021 was conducted. Study quality was assessed using the Checklist for Artificial Intelligence in Medical Imaging (CLAIM). Detection meta-analysis was performed using a unified hierarchical model. Segmentation studies were evaluated using a random effects model. Sensitivity analysis was performed for externally validated studies. RESULTS: Of 224 studies included in the systematic review, 46 segmentation and 38 detection studies were eligible for meta-analysis. In detection, DL achieved a lower false positive rate compared to TML; 0.018 (95% CI, 0.011 to 0.028) and 0.048 (0.032 to 0.072) (P < .001), respectively. In segmentation, DL had a higher dice similarity coefficient (DSC), particularly for tumor core (TC); 0.80 (0.77 to 0.83) and 0.63 (0.56 to 0.71) (P < .001), persisting on sensitivity analysis. Both manual and automated whole tumor (WT) segmentation had “good” (DSC ≥ 0.70) performance. Manual TC segmentation was superior to automated; 0.78 (0.69 to 0.86) and 0.64 (0.53 to 0.74) (P = .014), respectively. Only 30% of studies reported external validation. CONCLUSIONS: The comparable performance of automated to manual WT segmentation supports its integration into clinical practice. However, manual outperformance for sub-compartmental segmentation highlights the need for further development of automated methods in this area. Compared to TML, DL provided superior performance for detection and sub-compartmental segmentation. Improvements in the quality and design of studies, including external validation, are required for the interpretability and generalizability of automated models

A Dual-band Microstrip Slotted Antenna for UHF and Microwave RFID Readers

In this paper a new and simple dual-band microstrip slot antenna design combined with two inverted L-shaped slots integrated in the radiating patch is presented. This antenna is suitable for operating at 915 MHz and 2.45 GHz in order to cover the Radio Frequency Identification (RFID) frequencies bands. By optimizing the structure design, good performances in term of return loss radiation pattern and efficiency are achieved. The simulation results were obtained by using ADS and CST Microwave Studio electromagnetic solvers. The proposed antenna is mounted on an FR4 substrate with dielectric permittivity constant 4.4, thickness of 1.6 mm and loss tangent of 0.025 and a total area of 48×47 mm2. The design methodology used to achieve the dual-band antenna and both experimental, simulated results are presented

SPATIAL DATA INFRASTRUCTURE. BENEFITS AND STRATEGY

Nowadays, the geoscience data have become widely available in different organizations, which play a very important role in decisions-making at different levels (social, economic, political…). However, these organizations use standards, technologies and policies that differ from one to another. Therefore, this information is increasingly being distributed widely and become divorced from their original context or had remained limited to a small scale. Hence, the need for a spatial data infrastructure (SDI) becomes a necessity in order to facilitate the creation, sharing, and access to geospatial data, thus the exchange of knowledge between them, using a minimum set of standard practices, protocols, and specifications. The establishment of a spatial data infrastructure is to create conditions to ensure free access of public authorities, local authorities, organizations and citizens to spatial data. This paper presents a preliminary study of implementation of a spatial data infrastructure. It introduced the SDI developments in USA, Canada and Europe and summarized the relevant benefits