Major results from the first plasma campaign of the Wendelstein 7-X stellarator

After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter configuration employed during the first operational campaign. At power levels of 4 MW central electron densities reached 3 x 1019 m-3, central electron temperatures reached values of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this first operational phase include a first assessment of power balance and energy confinement, ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass absorption, and current drive experiments using electron cyclotron current drive. As in many plasma discharges the electron temperature exceeds the ion temperature significantly, these plasmas are governed by core electron root confinement showing a strong positive electric field in the plasma centre.This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the EURATOM research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission

Ribbon homology cobordisms

We study 4-dimensional homology cobordisms without 3-handles, showing that they interact nicely with Thurston geometries, character varieties, and instanton and Heegaard Floer homologies. Using these, we derive obstructions to such cobordisms, with topological applications.Comment: 50 pages, 6 figures. Major reorganization of sections for improved exposition. Result on Dehn surgery extended from Seifert fibered homology spheres to rational homology sphere

A DEA-inspired approach to selecting parking areas for dangerous-goods trucks

The transport of dangerous goods by trucks requires special conditions for rest areas. By considering the set of existing service areas, the present work develops a procedure for selecting the subgroup of the most suitable service areas for modification in order to provide a service to dangerous-goods transporters. Under multiple criteria, a new DEA-inspired model is developed that uses the main characteristics of the problem under study with the goal of selecting the best locations. Through the application of this model to Spanish territory with the help of Geographical Information Systems, various solutions are suggested. The final decision on the number of areas to be located depends on corresponding authorities, whose main priority is to satisfy economic criteria

A colour atlas of diseases of the vulva and perigenital area

This international congress will put a lot of work into female health. We therefore de\uaccided to present our clinical experience about an issue that is rarely discussed in der\uacmatological congresses, i.e. the diseases of the vulva and perigenital area. The diseases will be divided into different chapters: hereditary diseases (Darier disease); infectious diseases (herpes genitalis, genital warts, candidiasis, impetigo, erysipelas, syphilis); inflammatory diseases (allergic contact dermatitis, fixed drug eruption, psoriasis, lichen planus, lichen sclerosus, pemphigus) and neoplastic dis\uaceases (bowenoid papulosis, basal cell carcinoma, Bowen's disease, squamous cell carcinoma, extra-mammary Paget's disease, melanoma, Kaposi's sarcoma, T-cell lym\uacphoma and Langerhans' cell histiocytosis). All these diseases will be discussed ac\uaccording to clinical, histopathological and therapeutical points of view

Designed intramolecular blocking of the spin crossover of an Fe(II) complex

A ligand derived from 1,3bpp (2-(pyrazol-1-yl)-6-(pyrazol-3-yl)- pyridine) has been prepared to prove that the spin crossover (SCO) of an Fe(II) complex can be blocked by means of intramolecular interactions not related to the crystal field. Calculations show that the blocking is caused by the energy penalty incurred by the rotation of a phenyl ring, needed to avoid steric hindrance upon SCO

Collapsing molecular clouds with tracer particles: Part II, Collapse Histories

In order to develop a complete theory of star formation, one essentially needs to know two things: what collapses, and how long it takes. This is the second paper in a series, where we query how long a parcel of gas takes to collapse and the process it undergoes. We embed pseudo-Lagrangian tracer particles in simulations of collapsing molecular clouds, identify the particles that end in dense knots, and then examine the collapse history of the gas. We find a nearly universal behavior of cruise-then-collapse. We identify gas the moment before it collapses, $t_{\rm{sing}}$, and examine how it transitions to high density. We find that the time to collapse is uniformly distributed between $0.25 t_{\rm{ff}}$ and the end of the simulation at $\sim 1 t_{\rm{ff}}$, and that the collapse duration is universally short, $\Delta t \sim 0.1 t_{\rm{ff}}$. We find that the collapse of each core happens by a process akin to violent relaxation, wherein a fast reordering of the potential and kinetic energies occurs, in $0.1 t_{\rm{ff}}$, after which a virialized object remains. We describe the collapse in four stages; collection, hardening, singularity, and mosh. Collection sweeps low density gas into moderate density. Hardening brings kinetic and gravitational energies into quasi-equipartition. Singularity is the free-fall collapse, forming a virialized object in $\sim 0.1 t_{\rm{ff}}$. Mosh encompasses tidal dynamics of sub clumps and nearby cores during the collapse. In this work we focus primarily on isolated clumps. With this novel lens we can observe the details of collapse

Aprendiendo a argumentar entorno al concepto de cambio climático

La finalidad de este trabajo es presentar una propuesta didáctica orientada a desarrollar la capacidad de los alumnos para elaborar textos argumentativos basados en evidencias científicas (Osborne et al. , 2001), tomando como tema central el cambio climático. Se han analizado las principales dificultades del alumnado y las características de los textos elaborados. En la actividad se plantea a los estudiantes que defiendan su punto de vista, fundamentando su razonamiento científicamente y utilizando evidencias que corroboren sus opiniones. Especialmente, se promueve una reflexión crítica (Bartz, 2002) sobre el proceso de obtención y análisis de la información proveniente de diferentes fuentes, especialmente de Internet

Method to preserve the chiral-symmetry protection of the zeroth Landau level on a two-dimensional lattice

The spectrum of massless Dirac fermions on the surface of a topological insulator in a perpendicular magnetic field $B$ contains a $B$-independent "zeroth Landau level", protected by chiral symmetry. If the Dirac equation is discretized on a lattice by the method of "Wilson fermions", the chiral symmetry is broken and the zeroth Landau level is broadened when $B$ has spatial fluctuations. We show how this lattice artefact can be avoided starting from an alternative nonlocal discretization scheme introduced by Stacey. A key step is to spatially separate the states of opposite chirality in the zeroth Landau level, by adjoining $+B$ and $-B$ regions.Comment: Contribution to a special issue of Annals of Physics in memory of Kostya Efeto