Comparison of Computed and Measured Performance of a Pulsed Inductive Thruster Operating on Argon Propellant

Pulsed inductive plasma accelerators are electrodeless space propulsion devices where a capacitor is charged to an initial voltage and then discharged through a coil as a high-current pulse that inductively couples energy into the propellant. The field produced by this pulse ionizes the propellant, producing a plasma near the face of the coil. Once a plasma is formed if can be accelerated and expelled at a high exhaust velocity by the Lorentz force arising from the interaction of an induced plasma current and the magnetic field. A recent review of the developmental history of planar-geometry pulsed inductive thrusters, where the coil take the shape of a flat spiral, can be found in Ref. [1]. Two concepts that have employed this geometry are the Pulsed Inductive Thruster (PIT)[2, 3] and the Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD)[4]. There exists a 1-D pulsed inductive acceleration model that employs a set of circuit equations coupled to a one-dimensional momentum equation. The model was originally developed and used by Lovberg and Dailey[2, 3] and has since been nondimensionalized and used by Polzin et al.[5, 6] to define a set of scaling parameters and gain general insight into their effect on thruster performance. The circuit presented in Fig. 1 provides a description of the electrical coupling between the current flowing in the thruster I1 and the plasma current I2. Recently, the model was upgraded to include an equation governing the deposition of energy into various modes present in a pulsed inductive thruster system (acceleration, magnetic flux generation, resistive heating, etc.)[7]. An MHD description of the plasma energy density evolution was tailored to the thruster geometry by assuming only one-dimensional motion and averaging the plasma properties over the spatial dimensions of the current sheet to obtain an equation for the time-evolution of the total energy. The equation set governing the dynamics of the coupled electrodynamic-current sheet system is composed of first-order, coupled ordinary differential equations that can be easily solved numerically without having to resort to much more complex 2-D finite element plasma simulations

Análisis de ADN Mitocondrial en restos de hijo putativo de Luis XVI, Rey de Francia y María Antonieta

Carl Wilhelm Naundorff fue sepultado en 1845 en Delft como Luis Charles, Duque de Normandía, “Luis XVII”. Sin embargo, el hijo de Luis XVI y María Antonieta-Luis XVII- falleció oficialmente en el templo de París en 1795. Con el fin de determinar la identidad de Naundorff, se comparó las secuencias de las ondas del ADNmitocondrial (ADNmt) de sus restos con las secuencias obtenidas a partir del cabello de dos hermanas de María Antonieta, de la misma María Antonieta, y con las secuencias obtenidas de las muestras del ADN de dos parientes maternos vivos. La secuencia del ADNmt de una muestra de hueso de Naundorff mostró dos diferencias en los nucleótidos en cuanto a la secuencia del de las tres hermanas y cuatro diferencias en las secuencias de los parientes maternos vivos basado en esta evidencia resulta muy remoto que Naundorff sea el hijo de María Antonieta

BMI Development of Normal Weight and Overweight Children in the PIAMA Study

Background: There is evidence that rapid weight gain during the first year of life is associated with overweight later in life. However, results from studies exploring other critical periods for the development of overweight are inconsistent. Objective: The objective was to investigate BMI development to assess at what ages essential differences between normal weight and overweight children occur, and to assess which age intervals the most strongly influence the risk of overweight at 8 years of age. Methods: Longitudinal weight and height data

A randomised controlled trial of a community-based healthy lifestyle program for overweight and obese adolescents: the Loozit® study protocol

<p>Abstract</p> <p>Background</p> <p>There is a need to develop sustainable and clinically effective weight management interventions that are suitable for delivery in community settings where the vast majority of overweight and obese adolescents should be treated. This study aims to evaluate the effect of additional therapeutic contact as an adjunct to the Loozit^®group program – a community-based, lifestyle intervention for overweight and lower grade obesity in adolescents. The additional therapeutic contact is provided via telephone coaching and either mobile phone Short Message Service or electronic mail, or both.</p> <p>Methods and design</p> <p>The study design is a two-arm randomised controlled trial that aims to recruit 168 overweight and obese 13–16 year olds (Body Mass Index z-score 1.0 to 2.5) in Sydney, Australia. Adolescents with secondary causes of obesity or significant medical illness are excluded. Participants are recruited via schools, media coverage, health professionals and several community organisations. Study arm one receives the Loozit^®group weight management program (G). Study arm two receives the same Loozit^®group weight management program plus additional therapeutic contact (G+ATC). The 'G' intervention consists of two phases. Phase 1 involves seven weekly group sessions held separately for adolescents and their parents. This is followed by phase 2 that involves a further seven group sessions held regularly, for adolescents only, until two years follow-up. Additional therapeutic contact is provided to adolescents in the 'G+ATC' study arm approximately once per fortnight during phase 2 only. Outcome measurements are assessed at 2, 12 and 24 months post-baseline and include: BMI z-score, waist z-score, metabolic profile indicators, physical activity, sedentary behaviour, eating patterns, and psychosocial well-being.</p> <p>Discussion</p> <p>The Loozit^®study is the first randomised controlled trial of a community-based adolescent weight management intervention to incorporate additional therapeutic contact via a combination of telephone coaching, mobile phone Short Message Service, and electronic mail. If shown to be successful, the Loozit^®group weight management program with additional therapeutic contact has the potential to be readily translatable to a range of health care settings.</p> <p>Trial registration</p> <p>The protocol for this study is registered with the Australian Clinical Trials Registry (ACTRNO12606000175572).</p

High activity redox catalysts synthesized by chemical vapor impregnation

The use of precious metals in heterogeneous catalysis relies on the preparation of small nanoparticles that are stable under reaction conditions. To date, most conventional routes used to prepare noble metal nanoparticles have drawbacks related to surface contamination, particle agglomeration, and reproducibility restraints. We have prepared titania-supported palladium (Pd) and platinum (Pt) catalysts using a simplified vapor deposition technique termed chemical vapor impregnation (CVI) that can be performed in any standard chemical laboratory. These materials, composed of nanoparticles typically below 3 nm in size, show remarkable activity under mild conditions for oxidation and hydrogenation reactions of industrial importance. We demonstrate the preparation of bimetallic Pd–Pt homogeneous alloy nanoparticles by this new CVI method, which show synergistic effects in toluene oxidation. The versatility of our CVI methodology to be able to tailor the composition and morphology of supported nanoparticles in an easily accessible and scalable manner is further demonstrated by the synthesis of Pdshell–Aucore nanoparticles using CVI deposition of Pd onto preformed Au nanoparticles supported on titania (prepared by sol immobilization) in addition to the presence of monometallic Au and Pd nanoparticles

Étude en fonction de la température par R. M. M. du couplage quadripolaire de l'azote 14 dans un monocristal de nitrate de sodium

Prior studies by Bernheim and Gutowsky, Andrew et al. and d'Alessio and Scott on the 14N quadrupole coupling constant (q. c. c.) of sodium nitrate showed a relationship with the phase transition at T λ = 275 °C. We show the interest of studying the temperature dependence of the nitrogen q. c. c. This q. c. c. (745 kHz ± 2 % at 25 °C) could be measured between - 196 °C and + 285 °C by NMR on a single crystal. We observe that q. c. c. decreases more and more rapidly as the temperature increases up to Tλ, after which the q. c. c. continues to decrease. The intraionic contribution to the nitrogen q. c. c. in the nitrate ion is discussed in terms of the σ and π orbital populations in the nitrogen, and of the electric charges in the oxygen atoms. Estimating the crystalline contribution to the q. c. c. by two methods, we find that it is subtracting from the intraionic contribution, respectively, by an amount of 11 kHz or 38 kHz. Finally, the nitrogen q. c. c. decrease is well explained below room temperature by the Bayer- Kushida theory although its strong decrease at higher temperatures is not. This is in agreement with the recent theories about phase transition according to which NO3- ions undergo helicoïdal motions of high amplitude when the transition is approached.Après avoir rappelé les études effectuées par Bernheim et Gutowsky, Andrew et al. et d'Alessio et Scott sur le couplage quadripolaire (c. q.) du sodium en relation avec la transition de phase à Tλ = 275 °C, on montre l'intérêt que peut présenter l'étude du c. q. de l'azote en fonction de la température pour préciser le comportement des ions nitrates lorsque la température augmente. Ce c. q. (745 kHz ± 2 % à 25° C) a pu être mesuré, par R. M. N. sur un monocristal, entre - 196 °C et. + 285 °C. Il diminue de plus en plus rapidement quand la température s'élève jusqu'à Tλ et, au-delà, il décroît encore. La contribution intra-ionique au c. q. de l'azote de l'ion nitrate est ensuite discutée en fonction des populations des orbitales σ et π sur l'azote et des charges portées par les oxygènes. Deux évaluations distinctes donnent l'ordre de grandeur de la contribution cristalline (11 kHz ou 38 kHz selon le calcul) et montrent qu'elle se retranche de la contribution intra-ionique. Finalement la décroissance du c. q. de l'azote aux températures inférieures à l'ambiante s'interprète bien par la théorie de Bayer-Kushida ; par contre, cette théorie ne rend pas compte de la forte décroissance du c. q. au-dessus de l'ambiante, et cela s'explique avec les dernières théories relatives à l'existence de mouvements hélicoïdaux de grande amplitude des ions NO3- accompagnant la transition de phase