ARIES-AT Magnet Systems

This report presents a conceptual design of the magnet systems for an advanced tokamak fusion reactor (ARIES-AT). The main focus of the paper is to anticipate and extrapolate the current state-of-the-art in high temperature superconductors and coil design, and apply them to an advanced commercial fusion reactor concept. The current design point is described and supported with a preliminary structural analysis and a discussion of the merits, performance, and economics of high temperature vs. low temperature superconductors in an advanced fusion tokamak reactor design

Dynamics of Density Cavities Generated by Frictional Heating: Formation, Distortion, and Instability

A simulation study of the generation and evolution of mesoscale density cavities in the polar ionosphere is conducted using a time-dependent, nonlinear, quasi-electrostatic model. The model demonstrates that density cavities, generated by frictional heating, can form in as little as 90 s due to strong electric fields of ∼120 mV/m, which are sometimes observed near auroral zone and polar cap arcs. Asymmetric density cavity features and strong plasma density gradients perpendicular to the geomagnetic field are naturally generated as a consequence of the strong convection and finite extent of the auroral feature. The walls of the auroral density cavities are shown to be susceptible to large-scale distortion and gradient-drift instability, hence indicating that arc-related regions of frictional heating may be a source of polar ionospheric density irregularities

Dependence of Maximum Trappable Field on Superconducting Nb3Sn Cylinder Wall Thickness

Uniform dipole magnetic fields from 1.9 to 22.4 kOe were permanently trapped, with high fidelity to the original field, transversely to the axes of hollow Nb3Sn superconducting cylinders. These cylinders were constructed by helically wrapping multiple layers of superconducting ribbon around a mandrel. This is the highest field yet trapped, the first time trapping has been reported in such helically wound taped cylinders, and the first time the maximum trappable field has been experimentally determined as a function of cylinder wall thickness.Comment: 8 pages, 4 figures, 1 table. PACS numbers: 74.60.Ge, 74.70.Ps, 41.10.Fs, 85.25.+

Conflicting discourses of church youths on masculinity and sexuality in the context of HIV in Kinshasa, Democratic Republic of Congo

Masculinity studies are fairly new and young churchgoers are an under-researched group in the current Congolese church context. In response to this knowledge gap, this paper attempts to explore discourses of young  churchgoers from deprived areas of Kinshasa regarding masculinity and sexuality in the era of HIV. A series of 16 semi-structured interviews were conducted with unmarried young churchgoers from the Salvation Army, Protestant and Revival churches. The interviews were tape-recorded, transcribed verbatim and analysed using discourse analysis. Five main discourses emerged: ‘we are aware of the church message on sex’, ‘young men need sex’, ‘young women need money’, ‘to use or not to use condoms’ and ‘we trust in the church message’. Although all informants knew and heard church messages against premarital sex, many of them were sexually active. The perception was that young men were engaged in sexual activities with multiple partners as a result of sexual motivations surrounding masculinity and sexual potency, while young women sought multiple partners through transactional and intergenerational sex for economic reasons. These sexual practices of young people conflicted with church messages on sexual abstinence and faithfulness. However, a small number of participants challenged current gender norms and suggested alternative ways of being a man or a woman. To elucidate these  alternatives, we suggest that church youths and church leaders might take concrete actions to deconstruct misconceptions about being men. In this way, they can possibly enhance a frank and fruitful dialogue on sex, sexuality and gender to promote positive masculinities and constructive partnerships to prevent HIV.Keywords: masculinity, sexuality, young churchgoers, HIV prevention, gender equality, DR CongoDans le contexte actuel des e´glises Congolaises, les e´tudes relatives a` la masculinite´ sont presque re´centes et les jeunes chre´tiens constituent un groupe d’individus qui ne font pas l’objet des recherches scientifiques  approfondies. En re´ponse a` cette insuffisance de connaissances dans le contexte a` VIH, le pre´sent article tente d’explorer les discours relatifs a` la masculinite´ et a` la sexualite´ des jeunes chre´tiens issus des  quartiers de´favorise´s de Kinshasa. Une se´rie de 16 interviews semi-structure´es ont e´te´ mene´s aupre`s des jeunes chre´tiens ce´libataires appartenant a` l’Arme´e du Salut, aux e´glises Protestantes et a` celles du Re´veil du Congo. Les interviews ont e´te´ enregistre´es et analyse´es en utilisant la me´thode du discours. Cinq discours ont e´merge´ notamment: « Nous connaissons le message des e´glises au sujet du sexe », « les garc¸ons ont besoin des rapports sexuels », « les filles ont besoin d’argent », « faudrait-il utiliser ou ne pas utiliser les condoms » et « nous croyons dans le message des e´glises ». Alors que tous les participants  connaissaient le message des e´glises qui interdisent les rapports sexuels pre´maritaux, beaucoup d’entre eux e´taient de´ja` sexuellement actifs. Les garc¸ons ont e´te´ perc¸us comme des personnes qui ont des rapports sexuels avec plusieurs partenaires concomitants pour prouver leur masculinite´ et leur puissance sexuelle. Les filles chercheraient a` avoir des rapports sexuels mercantiles et interge´ne´rationnels avec des partenaires  multiples a` des fins e´conomiques. Ces pratiques sexuelles des jeunes s’opposent aux discours des e´glises  qui promeuvent l’abstinence sexuelle et la fide´lite´. Cependant, quelques participants ont remis en cause les normes courantes du genre et ont sugge´re´ des alternatives en ce qui concerne l’identite´ des hommes et des femmes. Pour les e´lucider, nous proposons que les jeunes chre´tiens et les leaders des e´glises puissent mener des actions concre`tes dans le but de de´construire les conceptions errone´es de ce que veut dire eˆtre homme. Ce faisant, ils peuvent probablement maximiser les chances d’un dialogue franc et productif en ce qui concerne le sexe, la sexualite´ et le genre afin de promouvoir la masculinite´ positive et le partenariat  constructif, susceptibles de pre´venir l’infection a` VIH.Mots cle´s: masculinite´, sexualite´, jeunes chre´tiens, pre´vention du VIH, e´galite´ du genre, RD Cong

A multi-isotope approach to evaluate the potential of great cormorant eggs for contaminant monitoring

Contaminant monitoring in biota is important for determining environmental status and to detect or prioritize action on hazardous substances. Predators higher up a food chain are often used for monitoring of contaminants that bioaccumulate. However, it is not always possible to find higher predators that are both abundant and have a wide distribution for national or international contaminant monitoring. Great cormorants (Phalocrocorax carbo) are a widespread and increasingly common top predator of fish in fresh, brackish and salt water. We evaluate the suitability of great cormorant eggs as a matrix for contaminant monitoring by using stable isotopes of carbon, nitrogen and sulfur. Despite the fact that cormorants are migratory, egg isotope values showed a significant separation between five breeding colonies in Sweden (1 fresh water lake, 3 Baltic sites and 1 marine site). This high degree of separation indicates that eggs are primarily produced using local resources (not stored body resources) and that contaminants (mercury concentrations in this study) measured in eggs likely reflect levels in fish prey caught close to the breeding area. Compound specific stable isotope analysis was used to estimate cormorant trophic position (TP) and concentrations of mercury in eggs were positively related to TP. The results show that a multi-isotope approach, combined with good ecological diet knowledge allow for meaningful and comparative interpretation of mercury concentrations in biota and that great cormorant eggs appear a suitable matrix to measure locally derived and maternally transferred contaminants

NH11B-1726: FrankenRaven: A New Platform for Remote Sensing

Small, modular aircraft are an emerging technology with a goal to maximize flexibility and enable multi-mission support. This reports the progress of an unmanned aerial system (UAS) project conducted at the NASA Ames Research Center (ARC) in 2016. This interdisciplinary effort builds upon the success of the 2014 FrankenEye project to apply rapid prototyping techniques to UAS, to develop a variety of platforms to host remote sensing instruments. In 2016, ARC received AeroVironment RQ-11A and RQ-11B Raven UAS from the US Department of the Interior, Office of Aviation Services. These aircraft have electric propulsion, a wingspan of roughly 1.3m, and have demonstrated reliability in challenging environments. The Raven airframe is an ideal foundation to construct more complex aircraft, and student interns using 3D printing were able to graft multiple Raven wings and fuselages into FrankenRaven aircraft. Aeronautical analysis shows that the new configuration has enhanced flight time, payload capacity, and distance compared to the original Raven. The FrankenRaven avionics architecture replaces the mil-spec avionics with COTS technology based upon the 3DR Pixhawk PX4 autopilot with a safety multiplexer for failsafe handoff to 2.4 GHz RC control and 915 MHz telemetry. This project demonstrates how design reuse, rapid prototyping, and modular subcomponents can be leveraged into flexible airborne platforms that can host a variety of remote sensing payloads and even multiple payloads. Modularity advances a new paradigm: mass-customization of aircraft around given payload(s). Multi-fuselage designs are currently under development to host a wide variety of payloads including a zenith-pointing spectrometer, a magnetometer, a multi-spectral camera, and a RGB camera. After airworthiness certification, flight readiness review, and test flights are performed at Crows Landing airfield in central California, field data will be taken at Kilauea volcano in Hawaii and other locations

Onsala Space Observatory – IVS Technology Development Center Activities during 2017–2018

We give a brief overview of the technical development related to geodetic VLBI done during 2017 and 2018 at the Onsala Space Observatory