95 research outputs found

    Magnetophonon Resonance in Quantum Wells with Parabolic Potential

    Get PDF
    The linear dc magnetoconductivity in the(x,y)(x,y) plane of a parabolic quantum well, with a magnetic fieldB⃗=Be⃗z\vec B = B\vec e_z applied, is evaluated for electron - opticalphonon interaction. For nonpolar optical and polar optical phonons,the magneto-conductivity oscillates as a function of the magneticfield with resonances occurring when Pωc=ω0P\omega_c=\omega_0, whereωc\omega_c and ω0\omega_0 are cyclotron frequency and optical phononfrequency, respectively, and where PP is an integer. The analyticresults are numerically evaluated to show explicitly the dependenceof magneto-conductivity on the magnetic field, the confinementfrequency in zz direction, and the temperature of the system

    Experiment-based Comparative Analysis of Nonlinear Speed Control Methods for Induction Motors

    Get PDF
    Field-oriented control (FOC) for induction motors is widely used in industrial applications. By using a fast and accurate torque controller based on a stator current controller it is possible to flexibly implement advanced speed control methods to achieve proper performance both in transient and steady-state states. In this study, a deadbeat controller was used for the current loop. The nonlinear methods used for the outer loop controller were backstepping, flatness-based control, and exact feedback linearization with state derivative. The dynamic responses of these three controls were compared through various experimental results. The advantages and disadvantages of the different control structures were analyzed and evaluated in detail. Based on this evaluation, an appropriate scheme can be specified when deployed in practice

    INTEGRATION OF CROSS-CULTURAL EXPERIENCES AND PROFESSIONAL COMPETENCIES: VIEWS FROM INTERNATIONAL EXCHANGE PROGRAMS IN HIGHER EDUCATION

    Get PDF
    Encouraging hospitality students in reflective and transformative learning toward a global mindset becomes an imperative for developing their cross-culturally professional competency in preparation of the future career path development. Oversea exchange programs are among the initiatives to raise personal, professional and cultural awareness for the hospitality students in a pathway to encourage cross-cultural learning among students in similar fields. However, to what extent the development of a global mindset gained from the cross-cultural experiences could help undergraduate hospitality students gain their professional competency in terms of cultural skills in the hospitality and tourism context is the main issue to be described by this study. Content analysis has been conducted on in-depth interview data given by hospitality oversea exchange students who are both current students and graduated ones. The most popular modes of international student exchanges such as team project, assignment, presentations, and travel exchanges are taken into consideration to highlight deeper insights into a mutual interest between the cross-cultural experiences and the professional competency related cultural skills. The study reveals that cultural understanding needs to be experienced in the real setting context. Furthermore, we also discovered that cultural exchange outcomes are normally obtained in the daily informal practices instead of formal studies. However, the current study is constrained within few selected countries where students have been experienced and the current partnership between the home and host Institutions. This paper provides actionable guidelines and approach for integrating the critical component of cultural exchange program in the traditional curriculum program of hospitality

    Current medical product development for diagnosis, surgical planning and treatment in the areas of Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery in Vietnam

    Get PDF
    With the population of 86 million and good GDP growth in recent decades, the medical market in Vietnam is growing fast. However, most of the medical technology products are imported, and the number of locally manufactured ones is limited and they do not have the high competition capability in term of quality, quantity and types. In this paper, the current product development in Vietnam for diagnosis, surgical planning and treatment in the areas of Rehabilitation, Neurosurgery, Orthopeadic and Dental-Cranio-Maxillofacial surgery is presented. A roadmap for medical technology development in Vietnam is propose

    On the Performance of Cognitive Underlay SIMO Networks over Equally Correlated Rayleigh Fading Channels

    Get PDF
    The performance of single-input multiple-output (SIMO) cognitive spectrum sharing networks with the presence of equally correlated Rayleigh fading channels is investigated. In particular, based on the truncated infinitive series of cumulative distribution function (CDF) and probability density function (PDF) of the end-to-end signal-to-noise ratios (SNRs), close-form expressions are provided for the system outage performance, bit error rate and ergodic capacity. It is shown that the system performance merely depends on the correlation coefficient between antennas. Monte-Carlo simulations are also contributed to confirm the accuracy of our analysis

    Autologous Transplantation of Adipose-Derived Stem Cells to Treat Acute Spinal Cord Injury: Evaluation of Clinical Signs, Mental Signs, and Quality of Life

    Get PDF
    BACKGROUD: Spinal cord injury (SCI) is damage that can cause a temporary or permanent change in spinal cord functions AIM: This work evaluates clinical signs, mental signs, and quality of life (QoL) after autologous adipose-derived stem cells (ADSCs) transplantation to treat acute spinal cord injury (SCI). MATERIAL AND METHODS: In this study, 47 SCI patients were recruited and divided into two groups: intervention and control. ADSCs were isolated and cultured under the cell culture quality control procedure. All patients in both groups underwent neurosurgery with or without ADSC transplantation. The recovery regarding neurological muscle, QoL, neurogenic bladder, and mental improvement was assessed after transplantation. RESULTS: All patients had improved in terms of motor function, bladder function, and daily living. No patients reported any side effect. MRI imaging showed significant changes in the lesion length of the spinal canal and the thickening of the spinal cord. Mental improvement was highest at six months after transplantation and lowest at one month after transplantation. The proportion of patients whose quality of life improved after treatment was 100%, while 80% of patients were satisfied with treatment outcomes. CONCLUSIONS: Thus, our data suggested that ADSCs transplantation was safe and effective for the treatment of SCI patients. Neurological muscle and neurogenic bladder were improved significantly after transplantation

    Synthesis of Gold Nanobipyramids by Seed-mediated Method and Santibacterial Activities

    Get PDF
    Metallic nanoparticles as antibacterial agents have been studied for several years. The most used antibacterial nanoparticles are silver nanoparticles. The mechanisms and  antibacterial properties of silver nanoparticles are well known, but the effects of gold nanoparticles, especially gold Nano bipyramids, are not considered. In this research, we synthesized gold nanobipyramids (NBPs) by seed mediated method using surfactant cetyltrimethylammonium bromide (CTAB). After preparing, gold nanobipyramids is removed CTAB and modified the surface using polyethylene glycol, polyvinyl alcohol and chitosan as the stabilizers. Besides, antibacterial effects of gold nanobipyramids on both Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) are investigated in this paper. The results show that gold nanobipyramids have good antibacterial activities even at low concentration. The optimal concentration of stabilizers and gold nanobipyramids in antibacterial activities are also studied in this paper

    Lovastatin for the Treatment of Adult Patients With Dengue: A Randomized, Double-Blind, Placebo-Controlled Trial.

    Get PDF
    BACKGROUND: Dengue endangers billions of people in the tropical world, yet no therapeutic is currently available. In part, the severe manifestations of dengue reflect inflammatory processes affecting the vascular endothelium. In addition to lipid lowering, statins have pleiotropic effects that improve endothelial function, and epidemiological studies suggest that outcomes from a range of acute inflammatory syndromes are improved in patients already on statin therapy. METHODS: Following satisfactory review of a short pilot phase (40 mg lovastatin vs placebo in 30 cases), we performed a randomized, double-blind, placebo-controlled trial of 5 days of 80 mg lovastatin vs placebo in 300 Vietnamese adults with a positive dengue NS1 rapid test presenting within 72 hours of fever onset. The primary outcome was safety. Secondary outcomes included comparisons of disease progression rates, fever clearance times, and measures of plasma viremia and quality of life between the treatment arms. RESULTS: Adverse events occurred with similar frequency in both groups (97/151 [64%] placebo vs 82/149 [55%] lovastatin; P = .13), and were in keeping with the characteristic clinical and laboratory features of acute dengue. We also observed no difference in serious adverse events or any of the secondary outcome measures. CONCLUSIONS: We found lovastatin to be safe and well tolerated in adults with dengue. However, although the study was not powered to address efficacy, we found no evidence of a beneficial effect on any of the clinical manifestations or on dengue viremia. Continuing established statin therapy in patients who develop dengue is safe.Chinese Clinical Trials Registration. ISRCTN03147572

    SWIPT-enabled cooperative wireless IoT networks with friendly jammer and eavesdropper: Outage and intercept probability analysis

    Get PDF
    Physical layer security (PLS) and simultaneous wireless information and power transfer (SWIPT) in cooperative relaying have gained great interest as technologies for security and energy enhance ment in Internet-of-Things (IoT) networks. In this work, we investigate PLS for a SWIPT- and AF-enabled cooperative wireless IoT system, consisting of one source, multiple energy harvesting (EH) relays, and one destination, in the presence of an eavesdropper that tries to overhear the confidential information. Furthermore, an EH-friendly jammer is deployed to transmit jamming signals aimed at the eavesdropper to improve the security system. In this context, a low-complexity, sub-optimal, but efficient relay selection method is proposed. More specifically, the relay is selected to convey information such that it has the best channel to the source. Based on the proposed system model, the performance analysis of the intercept probability (IP), asymptotic IP, and non-zero secrecy probability (NZSP) is analyzed by considering the time switching (TS)-based relaying strategy. Particularly, the exact closed-form expression of IP is achieved by applying modified Bessel function expansion. Monte-Carlo simulations are employed to corroborate the correctness and efficiency of our mathematical analysis. The time splitting factor α makes variations on the IP of about 3× as α ∈ [0.1, 0.8]. However, a dramatic reduction of the IP up to 317× is observed as α increases from 0.8 to 0.9.Web of Science11861778616
    • …
    corecore