Plasma heating due to X-B mode conversion in a cylindrical ECR plasma system

Extra Ordinary (X) mode conversion to Bernstein wave near Upper Hybrid Resonance (UHR) layer plays an important role in plasma heating through cyclotron resonance. Wave generation at UHR and parametric decay at high power has been observed during Electron Cyclotron Resonance (ECR) heating experiments in toroidal magnetic fusion devices. A small linear system with ECR and UHR layer within the system has been used to conduct experiments on X-B conversion and parametric decay process as a function of system parameters. Direct probing {\em in situ} is conducted and plasma heating is evidenced by soft x-ray emission measurement. Experiments are performed with hydrogen plasma produced with 160-800 W microwave power at 2.45 GHz of operating frequency at $10^{-3}$ mbar pressure. The axial magnetic field required for ECR is such that the resonant surface (B = 875 G) is situated at the geometrical axis of the plasma system. Experimental results will be presented in the paper.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Temperature dependence of the resistance of metallic nanowires (diameter ≥\geq 15 nm): Applicability of Bloch-Gr\"{u}neisen theorem

We have measured the resistances (and resistivities) of Ag and Cu nanowires of diameters ranging from 15nm to 200nm in the temperature range 4.2K-300K with the specific aim to assess the applicability of the Bloch-Gr\"{u}neisen formula for electron phonon resistivity in these nanowires. The wires were grown within polymeric templates by electrodeposition. We find that in all the samples the resistance reaches a residual value at T=4.2K and the temperature dependence of resistance can be fitted to the Bloch-Gr\"{u}neisen formula in the entire temperature range with a well defined transport Debye temperature ($\Theta_{R}$). The value of Debye temperature obtained from the fits lie within 8% of the bulk value for Ag wires of diameter 15nm while for Cu nanowires of the same diameter the Debye temperature is significantly lesser than the bulk value. The electron-phonon coupling constants (measured by $\alpha_{el-ph}$ or $\alpha_{R}$) in the nanowires were found to have the same value as that of the bulk. The resistivities of the wires were seen to increase as the wire diameter was decreased. This increase in the resistivity of the wires may be attributed to surface scattering of conduction electrons. The specularity p was estimated to be about 0.5. The observed results allow us to obtain the resistivities exactly from the resistance and gives us a method of obtaining the exact numbers of wires within the measured array (grown within the template).Comment: 9 pages, 10 figure

Hundred joules plasma focus device as a potential pulsed source for in vitro cancer cell irradiation

Indexación: Web of Science; Scopus.Plasma focus devices may arise as useful source to perform experiments aimed to study the effects of pulsed radiation on human cells in vitro. In the present work, a table top hundred joules plasma focus device, namely "PF-400J", was adapted to irradiate colorectal cancer cell line, DLD-1. For pulsed x-rays, the doses (energy absorbed per unit mass, measured in Gy) were measured using thermoluminescence detectors (TLD-100 dosimeters). The neutron fluence and the average energy were used to estimate the pulsed neutron doses. Fifty pulses of x-rays (0.12 Gy) and fifty pulses of neutrons (3.5 μGy) were used to irradiate the cancer cells. Irradiation-induced DNA damage and cell death were assessed at different time points after irradiation. Cell death was observed using pulsed neutron irradiation, at ultralow doses. Our results indicate that the PF-400J can be used for in vitro assessment of the effect of pulsed radiation in cancer cell research.http://recursosbiblioteca.unab.cl:2296/doi/pdf/10.1063/1.499465

Balancing voices and views in socratic circle seminars: A self-study

Abstract: Object of study. My research revolves around Socratic Circle Seminars (SCSs) which are intellectual conversations and democratic discussions carried out between students and centered on exploring and interpreting common texts (Adler, 1982; Lambright, 1995; Copeland, 2005). This form of qualitative research and practitioner inquiry (Samaras, 2015) draws upon my 15 years of experience in implementing SCSs in Enriched English as a Second-Language (EESL) classrooms at the Académie Ste-Thérèse in Québec (2001-2017). Specifically, this Self-Study focuses on how I conducted three SCSs in my EESL classes in Secondary 5 (94 learners) in June 2017. Problem. Despite all my classroom experience with SCSs, my recalibration of practice, my production of resources as well as my outreach to the teaching and research community (Nelson, 2008, 2010, 2011, 2015a, 2015b), I still face the recurrent problem of uneven student participation as well as the unbalanced expression of viewpoints. This situation is explored from the vantage point of “living educational theory” (McNiff, Lomax, & Whitehead, 2003; McNiff & Whitehead, 2006; Samaras, 2011) by framing and reframing typical problems as disjunctions or discrepancies between practice and belief. General and Specific Research Objectives & Hypothesis. Generally, I seek to identify what needs to be done to get all learners to participate more actively in Socratic Circle Seminars so that the process of meaningful and democratic dialogue includes more voices and balances more views. Specifically, I will be looking to better align my practice with my belief by identifying “avoidable obstacles” through more strategic teaching. Research Design and Methodology. This research corresponds to “Reflexive Analysis of One’s Professional Practice” (Paillé, 2007). In terms of underlying methodological guidelines, I am applying the “Five Foci” framework of Self-Study Teacher Research (Samaras, 2011, p.94): 1) personal situated inquiry; 2) critical collaborative inquiry; 3) improved learning; 4) transparent and systemic research process; 5) knowledge generation and presentation. Data Analysis, Interpretation & Assessment. I collected and catalogued three types of data (Hendricks, 2006) from a variety of sources and in a variety of formats: 1) teacher-produced artefacts; 2) observational data; and 3) inquiry data. I employed “constant comparative method” (Creswell, 2007), presented the evidence into emerging and converging themes and later conducted a categorical analysis of the evidence. The data analysis and interpretation as well as my methodology was assessed by my Critical Friend Team to increase validity, ensure transparency and secure trustworthiness of findings. Summary conclusions. My findings show that I had been unintentionally short-circuiting my own better intentions about using SCSs to implement student-centered learning and participation. The most significant finding of my research shows the necessity of adopting a more pro-active coaching role as a teacher and developing very flexible and differentiated coaching skills. Originality of contribution. Beyond this specific educational context of second-cycle high-school EESL teaching in Québec, this study would be of special interest for those who wish to implement SCSs in their own classrooms in a more systematic way. Novice and seasoned teachers alike who read this study would be better prepared to understand tested practices that shape stronger participation in student-centered, democratic and academic conversations.Objet d’étude. Ce projet de recherche comporte une analyse réflexive entourant ma pratique dans l’enseignement des « Séminaires de Cercles Socratiques » (SCSs) au deuxième cycle du secondaire en tant qu’enseignant d’Anglais langue-seconde enrichi à l’Académie Ste-Thérèse au Québec. Les SCSs sont des conversations intellectuelles et discussions démocratiques centrées sur l’exploration et l’interprétation de sujets et de textes plus complexes (Adler, 1982; Lambright, 1995; Copeland, 2005). Plus précisément, ce projet de recherche qualitative propose une auto-analyse de ma pratique pédagogique (Samaras, 2015) avant, pendant et après trois SCSs pilotés dans des cours d’anglais enrichis en 5e secondaire (94 apprenants) au mois de juin 2017. Problématique. Malgré 15 ans d’expérience en classe avec les SCSs, le partage de mon expertise dans la communauté de la recherche en enseignement au Québec (Nelson, 2008, 2010, 2011, 2015a, 2015b), la production d’outils didactiques, ainsi que le réinvestissement de mes réflexions dans l’action pédagogique, les problèmes portant sur la participation active ainsi que l’expression plus équilibrée des perspectives multiples persistent. Cette situation est explorée à partir de la perspective d’un enseignant qui cherche à recadrer des problèmes typiques en tant que divergences entre ses croyances et sa pratique, selon le courant de « living educational theory » (McNiff, Lomax, Whitehead, 2003 ; McNiff & Whitehead, 2006 ; Samaras, 2011). Objectif général et objectif spécifique de recherche ainsi que l’hypothèse. Généralement, je cherche à identifier ce qui doit être fait afin de favoriser un plus grand nombre d’apprenants à participer dans les SCSs pour enclencher un processus de dialogue démocratique signifiant qui inclut plus de voix et balance plus de perspectives. Plus précisément, je cherche à mieux aligner ma pratique avec mes croyances tout en identifiant les « obstacles potentiels » à travers un enseignement plus stratégique. Modèle d’essai et méthodologie de recherche. Ce projet de recherche correspond à « une auto-analyse réflexive de sa pratique professionnelle » (Paillé, 2007). En termes méthodologiques, ce projet applique le cadre « Cinq Axes » ou « Five Foci Framework of Self-Study Teacher Research» (Samaras, 2011, p.94) qui comporte les principes récursifs et herméneutiques suivants : 1) investigation personnelle et située; 2) investigation critique et collaborative; 3) apprentissage amélioré; 4) processus systémique et transparent de recherche; 5) production et présentation du savoir. Analyse, intérprétation et validation des données. J’ai récolté et compilé trois types de données (Hendricks, 2006) provenant d’une variété de sources et de formats : 1) des artéfacts produits par l’enseignant; 2) des données observées; 3) des données d’évaluation. J’ai utilisé la « méthode constante et comparative » (Creswell, 2007), présenté des thèmes émergents de mes données afin d’en faire une analyse catégorique. Des membres de mon équipe d’amis critiques (Critical Friends Team) ont validé la méthodologie utilisée, ainsi que l’analyse et l’interprétation de données afin d’assurer la transparence, garantir la fiabilité et augmenter la crédibilité de ma recherche. Conclusions sommaires. Mes découvertes démontrent que j’étais en train de court-circuiter ma propre vision socio-constructiviste de l’apprentissage et l’enseignement au sein des SCSs. La découverte la plus probante de ma recherche porte sur la nécessité d’accorder une place plus importante au rôle de coach-enseignant. De plus, je dois dévellopper davantage des compétences flexibles et différenciées en coaching

Fractal Inspired Models of Quark and Gluon Distributions and Longitudinal Structure Function FL(x, Q2) at small x

In recent years, Fractal Inspired Models of quark and gluon densities at small x have been proposed. In this paper, we investigate longitudinal structure function F-L (x, Q2) within this approach. We make predictions using the QCD based approximate relation between the longitudinal structure function and the gluon density. As the Altarelli-Martinelli equation for the longitudinal structure function cannot be applied to Model I due to the presence of a singularity in the Bjorken x-space we consider Model II only. The qualitative feature of the prediction of Model II is found to be compatible with the QCD expectation.Comment: 11 pages, 4 figures, Accepted for publication on 10-07-2010 in Indian Journal of Physic

Thermal and spectrodcopic studies on the decomposition of [Ni{di(2-aminoethyl)amine}2] and [Ni(2,2':6',2"-terpyridine)2] Montmorillonite intercalated composites

Intercalated [Ni{di(2-aminoethyl)amine}2]-Montmorillonite (I) and [Ni(2,20:60,200-terpyridine)2]-Montmorillonite (II) composites have been synthesized and their thermal behavior studied by TG, DTG and DTA substantiated by XRD and IR spectroscopy. Thermal stabilities of the composites I and II were about 50 and 1508C higher, respectively, compared to their respective free metal complex salts. These results indicate that the metal complex with aromatic backboned ligands had higher thermal stability than that of the aliphatic one upon intercalation into layered clay. XRD data showed that on heating, the basal spacing (d001) of the I composite decreased gradually from 14.5

Expandase-like activity mediated cell-free conversion of ampicillin to cephalexin by Streptomyces sp. DRS I

Cell-free extracts of Streptomyces sp. DRS I converted ampicillin to cephalexin, presumably due to the activity of the enzyme, expandase. The extract was fractionated and characterized by colorimetric and chromatographic measurements coupled with disc-agar diffusion bioassay against an ampicillinresistant, cephalexin-sensitive E. coli strain. Though expandase could not be identified, the presence of a hitherto unreported expandase in Streptomyces sp. DRS I is suggested

Comparative performance of some popular ANN algorithms on benchmark and function approximation problems

We report an inter-comparison of some popular algorithms within the artificial neural network domain (viz., Local search algorithms, global search algorithms, higher order algorithms and the hybrid algorithms) by applying them to the standard benchmarking problems like the IRIS data, XOR/N-Bit parity and Two Spiral. Apart from giving a brief description of these algorithms, the results obtained for the above benchmark problems are presented in the paper. The results suggest that while Levenberg-Marquardt algorithm yields the lowest RMS error for the N-bit Parity and the Two Spiral problems, Higher Order Neurons algorithm gives the best results for the IRIS data problem. The best results for the XOR problem are obtained with the Neuro Fuzzy algorithm. The above algorithms were also applied for solving several regression problems such as cos(x) and a few special functions like the Gamma function, the complimentary Error function and the upper tail cumulative $\chi^2$-distribution function. The results of these regression problems indicate that, among all the ANN algorithms used in the present study, Levenberg-Marquardt algorithm yields the best results. Keeping in view the highly non-linear behaviour and the wide dynamic range of these functions, it is suggested that these functions can be also considered as standard benchmark problems for function approximation using artificial neural networks.Comment: 18 pages 5 figures. Accepted in Pramana- Journal of Physic

Isolation and screening of Streptomyces in soil of protected forest areas from the states of Assam and Tripura, India, for antimicribial metabolites

Objective. — To study the antimicrobial of Antinomycets, isolated from Northeast India. Material and methods. — A total of 110 actinomycetes strains were isolated from the soil samples collected from the protected forest soil from two States in Northeast India These were then characterized by conventional methods and assessed for their antagonistic activity preliminary against test microorganisms. Results. — Amongthe110isolates,65(59.09%)strainsshowedantibacterialactivity,47(42.72%) strains showed antifungal activity and 33 (30%) strains exhibited a broad-spectrum activity against both test bacteria and fungi. The production of nonpolyenic antifungal substances by promising isolates was investigated using several criteria: antibacterial activity, ergosterol inhibition, and UV—vis spectra of active extracts. Conclusion. — These results indicate that the protected areas of Northeast India’s soil microorganisms could be an interesting source of antibacterial and antifungal bioactive substances. # 2007 Elsevier Masson SAS. All rights reserved