Theory of transient spectroscopy of multiple quantum well structures

A theory of the transient spectroscopy of quantum well (QW) structures under a large applied bias is presented. An analytical model of the initial part of the transient current is proposed. The time constant of the transient current depends not only on the emission rate from the QWs, as is usually assumed, but also on the subsequent carrier transport across QWs. Numerical simulation was used to confirm the validity of the proposed model, and to study the transient current on a larger time scale. It is shown that the transient current is influenced by the nonuniform distribution of the electric field and related effects, which results in a step-like behavior of the current. A procedure of extraction of the QW emission time from the transient spectroscopy experiments is suggested.Comment: 5 pages, 4 figures, to be published in J. Appl. Phy

Comparison of Solvent-Free Microwave Extraction and Conventional Hydro-Distillation of Essential Oils from four Selected Underutilised Citrus sp. Plants

Essential oils (EOs) are widely used in cosmetic, pharmaceutical, fragrance and food industry. Solvent Free Microwave Extraction (SFME) is a green method for the extraction of essential oils from aromatic plants. The aim of the study is to compare SFME with conventional hydro-distillation (HD) technique, for the extraction of EO from four selected underutilised Citrus plant species in the essential oil industry; Citrus medica, C. reticulata, C. madurensis and C. limon in terms of chemical composition, antioxidant activity and energy consumption. The EOs were extracted using SFME (Microwave power: 700 W for 5 minutes and 400 W for 55 minutes) and HD (for 1 hour) and chemically analysed using Gas Chromatography (GC) and Gas Chromatography and Mass Spectrometry (GC-MS). The Antioxidant activity of the EOs were determined using Ferric Reducing Antioxidant Power (FRAP) and Total Polyphenolic Content (TPC) assays. The GC and GCMS identified 4(10)-Thujene (33.82%) as the major compound in C. medica oil, extracted by HD while that was L- terpinene-4-ol (18%) when extracted by SFME technique. The β-Linalool was the major component in C. reticulata (42.98%) and C. madurensis (37.95%) in SFME extracted EOs, however, it has been dropped down to 26.71% and 26.83% respectively during HD extraction. In C. limon, D-Limonene (43.069%) was abundant in HD- extracted EOs while it was (R)-(+)-Citronellal (39.08%) in SFME-extracted EO. SFME yielded EOs with higher amounts of more valuable oxygenated compounds with higher antioxidant capacities over HD. In comparison with HD, the SFME technique presented higher efficiency with reduced extraction times, costs and energy, yielding EOs with excellent chemical profiles and relatively high antioxidant activity.Keywords: Essential oils, Solvent free Microwave extraction, GC, GCMS, Antioxidan

Experience in the application of IEC/TR 61000-3-6 to harmonic allocation in transmission systems

Technical report IEC/TR 61000-3-6 is widely used as a guide to harmonic management in HV and MV networks, assisting in coordination of harmonic levels between utility and customer. In 2001, Australia and New Zealand adopted the harmonic standard AS/NZS 61000.3.6, which closely follows the above IEC technical report. As a result, transmission utilities and connected loads are required by government regulations to abide by the harmonic allocations set by the standard. The technical report contains some useful general principles which can be applied to the harmonic management of power systems. However, unexpected difficulties can be found when attempts are made to apply them to large power systems. The formal procedure recommended by the standard for calculation of harmonic emission levels limits the voltage at the point of connection. There can be situations where the highest harmonic voltages are remote from the PCC. This can be accounted for by taking into account interactions between each injecting load and all other busbars in one single step. This leads to the development of a harmonic allocation constant , which will apply to the entire transmission network, as a measure of the ability of the network to absorb harmonics without violating a set planning limit. At present, the allocation procedure given in the standard implies consideration of only a single network operation scenario. However, substantial variations have been identified in the harmonic behaviour of transmission networks, including harmonic absorption capacity, with changes in generator commitment and switching configuration. The proposed approach accounts for variations by taking data from multiple network scenarios. For the specification of an easily-measurable harmonic current emission level - rather than a harmonic voltage level - for a particular customer, the network harmonic impedance is necessary. This quantity can vary substantially at the one busbar in a transmission network. The application of a standardised hth harmonic impedance is proposed which is based on the fundamental frequency fault level at the PCC. IEC/TR 61000-3-6 gives no guidance as to methods of treating harmonic resonances in transmission systems. Resonances will occur in any transmission system with sufficient line lengths, and will impose substantial constraints on harmonic allocation if computer calculations are accepted without modification. It is unclear if these resonances are of practical importance, and it is proposed that resonance amplifications be limited to allow useful allocations until their importance has been established by field results

Optimizing CIGB-300 intralesional delivery in locally advanced cervical cancer

Background:We conducted a phase 1 trial in patients with locally advanced cervical cancer by injecting 0.5 ml of the CK2-antagonist CIGB-300 in two different sites on tumours to assess tumour uptake, safety, pharmacodynamic activity and identify the recommended dose.Methods:Fourteen patients were treated with intralesional injections containing 35 or 70 mg of CIGB-300 in three alternate cycles of three consecutive days each before standard chemoradiotherapy. Tumour uptake was determined using 99 Tc-radiolabelled peptide. In situ B23/nucleophosmin was determined by immunohistochemistry.Results:Maximum tumour uptake for CIGB-300 70-mg dose was significantly higher than the one observed for 35 mg: 16.1±8.9 vs 31.3±12.9 mg (P=0.01). Both, AUC 24h and biological half-life were also significantly higher using 70 mg of CIGB-300 (P<0.001). Unincorporated CIGB-300 diffused rapidly to blood and was mainly distributed towards kidneys, and marginally in liver, lungs, heart and spleen. There was no DLT and moderate allergic-like reactions were the most common systemic side effect with strong correlation between unincorporated CIGB-300 and histamine levels in blood. CIGB-300, 70 mg, downregulated B23/nucleophosmin (P=0.03) in tumour specimens.Conclusion:Intralesional injections of 70 mg CIGB-300 in two sites (0.5 ml per injection) and this treatment plan are recommended to be evaluated in phase 2 studies.Fil: Sarduy, M. R.. Medical-surgical Research Center; CubaFil: García, I.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Coca, M. A.. Clinical Investigation Center; CubaFil: Perera, A.. Clinical Investigation Center; CubaFil: Torres, L. A.. Clinical Investigation Center; CubaFil: Valenzuela, C. M.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Baladrón, I.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Solares, M.. Hospital Materno Ramón González Coro; CubaFil: Reyes, V.. Center For Genetic Engineering And Biotechnology Havana; CubaFil: Hernández, I.. Isotope Center; CubaFil: Perera, Y.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Martínez, Y. M.. Medical-surgical Research Center; CubaFil: Molina, L.. Medical-surgical Research Center; CubaFil: González, Y. M.. Medical-surgical Research Center; CubaFil: Ancízar, J. A.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Prats, A.. Clinical Investigation Center; CubaFil: González, L.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Casacó, C. A.. Clinical Investigation Center; CubaFil: Acevedo, B. E.. Centro de Ingeniería Genética y Biotecnología; CubaFil: López Saura, P. A.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes; ArgentinaFil: Gómez, R.. Elea Laboratories; ArgentinaFil: Perea Rodríguez, S. E.. Center For Genetic Engineering And Biotechnology Havana; Cuba. Centro de Ingeniería Genética y Biotecnología; Cub

Evaluation of the undergraduate family medicine programme of Faculty of Medicine, University of Kelaniya : quantitative and qualitative student feedback

Background: Worldwide there is an increasing emphasis on the importance of primary care. The ministry of health Sri Lanka issued a directive in 2016 that training of doctors in primary care should be strengthened. Medical students of the Faculty of Medicine, University of Kelaniya follow a 1 month long clinical appointment in family medicine in their fourth year of study. Methods: Feedback is taken from students on completion of the appointment. Half the students from each group complete a pre tested structured feedback questionnaire that consists of answers to questions based on a likert scale with a space for free comments. The other half provide qualitative feedback. In this evaluation data were gathered from 185 (98%) students from all eight clinical groups throughout the year 2016. Quantitative data were analysed using SPSS version 22. Inductive thematic analysis was used to analyse the qualitative data from the Round Robin activity and free comments from the questionnaire. Results: The qualitative feedback provided a richer indepth overview of student ideas on the appointment compared to the quantitative data. In reflection of a desire for learning to be of relevance students wanted clinically oriented teaching focused on management. They preferred active teaching learning methods such as the opportunity to conduct consultations and receive immediate feedback. Students had a high regard for the teaching sessions by general practitioners at their clinics. The appointment had created an interest in the discipline of family medicine which could have an impact on future choice of career. There were indications to suggest that student attitudes towards patients may have evolved to be more patient centred. Students appreciated the inclusive and low stress ambience of the learning environment. Conclusions and recommendations: Regular evaluation of teaching programmes helps maintain accountability of faculty and paves the way for more student centred teaching through the incorporation of students’ views in devising teaching methods. This evaluation found that qualitative feedback provided more descriptive material to reflect on and therefore improve teaching on the programme. It is recommended that more use should be made of qualitative methodologies in programme evaluations

Automobile Spare Parts System – Web Solution

“With the right spare parts on hand, your business can continue without ceasing operations even after a major malfuction, allowing you to avoid loss of crucial time and profits as you wait for the right parts to be delivered”. This system which is specialized in trading automobile spare parts claims to provide sufficient spare parts throughout the life cycle of products, to the clients in need, so as to achieve sustainability. This research discusses how such a system can be designed and implemented to assist clients in search of the best automobile parts that fits their purpose. The research paper has been divided in such a manner to explore and comprehend each and every aspect of the system in detail. Initially, the introduction will provide a simple overview of the system with details regarding what the system will achieve; this will be followed by the methodology of the implementation process. The functionalities of the proposed system will then be discussed with the entails of the testing methodologies and the outcomes

The Double Pulsar Eclipses I: Phenomenology and Multi-frequency Analysis

The double pulsar PSR J0737-3039A/B displays short, 30 s eclipses that arise around conjunction when the radio waves emitted by pulsar A are absorbed as they propagate through the magnetosphere of its companion pulsar B. These eclipses offer a unique opportunity to probe directly the magnetospheric structure and the plasma properties of pulsar B. We have performed a comprehensive analysis of the eclipse phenomenology using multi-frequency radio observations obtained with the Green Bank Telescope. We have characterized the periodic flux modulations previously discovered at 820 MHz by McLaughlin et al., and investigated the radio frequency dependence of the duration and depth of the eclipses. Based on their weak radio frequency evolution, we conclude that the plasma in pulsar B's magnetosphere requires a large multiplicity factor (~ 10^5). We also found that, as expected, flux modulations are present at all radio frequencies in which eclipses can be detected. Their complex behavior is consistent with the confinement of the absorbing plasma in the dipolar magnetic field of pulsar B as suggested by Lyutikov & Thompson and such a geometric connection explains that the observed periodicity is harmonically related to pulsar B's spin frequency. We observe that the eclipses require a sharp transition region beyond which the plasma density drops off abruptly. Such a region defines a plasmasphere which would be well inside the magnetospheric boundary of an undisturbed pulsar. It is also two times smaller than the expected standoff radius calculated using the balance of the wind pressure from pulsar A and the nominally estimated magnetic pressure of pulsar B.Comment: 9 pages, 7 figures, 3 tables, ApJ in pres

Do ACE inhibitors improve the response to exercise training in functionally impaired older adults? A randomized controlled trial

&lt;br&gt;Background: Loss of muscle mass and strength with ageing is a major cause for falls, disability, and morbidity in older people. Previous studies have found that angiotensin-converting enzyme inhibitors (ACEi) may improve physical function in older people. It is unclear whether ACEi provide additional benefit when added to a standard exercise training program. We examined the effects of ACEi therapy on physical function in older people undergoing exercise training.&lt;/br&gt; &lt;b&gt;Methods:&lt;/b&gt; Community-dwelling people aged ≥65 years with functional impairment were recruited through general (family) practices. All participants received progressive exercise training. Participants were randomized to receive either 4 mg perindopril or matching placebo daily for 20 weeks. The primary outcome was between-group change in 6-minute walk distance from baseline to 20 weeks. Secondary outcomes included changes in Short Physical Performance Battery, handgrip and quadriceps strength, self-reported quality of life using the EQ-5D, and functional impairment measured using the Functional Limitations Profile.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Results:&lt;/b&gt; A total of 170 participants (n = 86 perindopril, n = 84 placebo) were randomized. Mean age was 75.7 (standard deviation [SD] 6.8) years. Baseline 6-minute walk distance was 306 m (SD 99). Both groups increased their walk distance (by 29.6 m perindopril, 36.4 m placebo group) at 20 weeks, but there was no statistically significant treatment effect between groups (−8.6m [95% confidence interval: −30.1, 12.9], p = .43). No statistically significant treatment effects were observed between groups for the secondary outcomes. Adverse events leading to withdrawal were few (n = 0 perindopril, n = 4 placebo).&lt;p&gt;&lt;/p&gt; &lt;b&gt;Interpretation:&lt;/b&gt; ACE inhibitors did not enhance the effect of exercise training on physical function in functionally impaired older people.&lt;p&gt;&lt;/p&gt