Ensuring uniform thickness of the conductive coating on the inner surface of the hemispherical resonator by magnetron sputtering

The possibilities of technological ensuring of the uniformity of thickness distribution of a thin-film metal coating produced by magnetron sputtering on the inner surface of a thinwalled silica resonator made in the shape of a hemisphere are considered. The possibility of minimizing the thickness of the coating by optimizing the diameter of the annular magnetron emission zone in combination with the distance from the resonator to the target made of sprayed material is shown. A further increase in the evenness of thickness of the coating is possible on the basis of the use of a fixed screen with a hole, the shape and location of which are calculated analytically, and the final configuration of the contour is specified empirically

Higher-order synchronization on the sphere

We construct a system of $N$ interacting particles on the unit sphere $S^{d-1}$ in $d$-dimensional space, which has $d$-body interactions only. The equations have a gradient formulation derived from a rotationally-invariant potential of a determinantal form summed over all nodes, with antisymmetric coefficients. For $d=3$, for example, all trajectories lie on the $2$-sphere and the potential is constructed from the triple scalar product summed over all oriented $2$-simplices. We investigate the cases $d=3,4,5$ in detail, and find that the system synchronizes from generic initial values, for both positive and negative coupling coefficients, to a static final configuration in which the particles lie equally spaced on $S^{d-1}$. Completely synchronized configurations also exist, but are unstable under the $d$-body interactions. We compare the relative effect of $2$-body and $d$-body forces by adding the well-studied $2$-body interactions to the potential, and find that higher-order interactions enhance the synchronization of the system, specifically, synchronization to a final configuration consisting of equally spaced particles occurs for all $d$-body and $2$-body coupling constants of any sign, unless the attractive $2$-body forces are sufficiently strong relative to the $d$-body forces. In this case the system completely synchronizes as the $2$-body coupling constant increases through a positive critical value, with either a continuous transition for $d=3$, or discontinuously for $d=5$. Synchronization also occurs if the nodes have distributed natural frequencies of oscillation, provided that the frequencies are not too large in amplitude, even in the presence of repulsive 2-body interactions which by themselves would result in asynchronous behaviour.

Redesigning the Jefferson Lab Hall A beam line for high precision parity experiments

The Continuous Electron Beam Accelerator Facility (CEBAF) was built with a thermionic electron source and the three original experimental hall lines reflected this. A few years after beam delivery began a parity violation experiment was approved and two polarimeters were installed in the Hall A beam line. The beam raster system was placed after the new Compton polarimeter, before one accelerator quadrupole and four quadrupoles in the new Moller polarimeter. It was very difficult to meet experimental requirements on envelope functions and raster shape with this arrangement so a sixth quadrupole was installed downstream of the Moller polarimeter to provide an additional degree of freedome. All of the parity experiments in Hall A have been run with this still-unsatisfactory configuration. The MOLLER experiment is predicated on achieving a 2% error on a 32 ppb asymmetry. Beam line changes are required to meet the systematic error budget. This paper documents the existing beam line, an interim change which can be accomplished during a annual maintenance down, and the final configuration for MOLLER and subsequent experiments.

Comparison of under-actuated and fully-actuated serial robotic arms: a case study

Under-actuated robots are very interesting in terms of cost and weight since they can result in a state-controllable system with a number of actuators lower than the number of joints. In this paper, a comparison between an under-actuated planar 3 degrees of freedom (DOF) robot and a comparable fully-actuated 2 degrees of freedom robot is presented, mainly focusing on the performances in terms of trajectories, actuator torques, and vibrations. The under-actuated system is composed of 2 active rotational joints followed by a passive rotational joint equipped with a torsional spring. The fully-actuated robot is inertial equivalent to the under-actuated manipulator: the last link is equal to the sum of the last two links of the under-actuated system. Due to the conditions on the inertia distribution and spring placement, in a simple point-to-point movement the last passive joint starts and ends in a zero-value configuration, so the 3 DOF robot is equivalent, in terms of initial and final configuration, to the 2 DOF fully-actuated robot, thus they can be compared. Results show how while the fully actuated robot is better in terms of reliable trajectory and actuator torques, the under-actuated robot wins in flexibility and vibration behavior.

Merger of galactic cores made of ultralight bosonic dark matter

We study binary mergers of ultralight bosonic dark matter cores by solving the Gross-Pitaevskii- Poisson system of equations. The analysis centers on the dynamics of the relaxation process and the behavior of the configuration resulting from the merger, including the Gravitational Cooling with its corresponding emission of mass and angular momentum. The oscillations of density and size of the final configuration are characterized, indicating that for the equal mass case the dependency of the amplitude and frequency of these oscillations on the impact parameter of the pre-merger config- uration is linear. The amplitude of these oscillations changes by a factor of two or more indicating the final configuration does not approach a clear stationary state even though it oscillates around a virialized state. For the unequal mass case, global quantities also indicate the final configuration oscillates around a virialized state, although the density does not show a dominant oscillation mode. Also the evolution of the angular momentum prior and post merger is analyzed in all cases.

Finding Cut-Offs in Leaderless Rendez-Vous Protocols is Easy

In rendez-vous protocols an arbitrarily large number of indistinguishable finite-state agents interact in pairs. The cut-off problem asks if there exists a number B such that all initial configurations of the protocol with at least B agents in a given initial state can reach a final configuration with all agents in a given final state. In a recent paper [17], Horn and Sangnier prove that the cut-off problem is equivalent to the Petri net reachability problem for protocols with a leader, and in "Image missing" for leaderless protocols. Further, for the special class of symmetric protocols they reduce these bounds to "Image missing" and "Image missing" , respectively. The problem of lowering these upper bounds or finding matching lower bounds is left open. We show that the cut-off problem is "Image missing" -complete for leaderless protocols, "Image missing" -complete for symmetric protocols with a leader, and in "Image missing" for leaderless symmetric protocols, thereby solving all the problems left open in [17].

Reabilitação estética sobre implantes com prótese total fixa cerâmica – relato de caso

Oral rehabilitation with fully ceramic implant-supported prostheses is one of the treatment options that presents clinical longevity and patient satisfaction. However, complications regarding the chipping are reported in the literature. To reduce these problems, the use of monolithic zirconia is constantly suggested. Another option, not so reported, are the modifications in the final configuration of the cover ceramic. The design of the chosen materials is discussed. The choice of prosthesis type and gingival conditioning to achieve an adequate emergency profile is also described. This clinical report describes an aesthetic rehabilitation of the maxilla with all-ceramic prosthesis and application of the cover ceramic only on the buccal surface by PF-1 implant-supported.

El sitio de modo técnico 3 de la antigua fábrica de conservas Garavilla (Algeciras, Cádiz). Análisis tecnológico de los soportes líticos = Technical Mode 3 site of the Ancient Fábrica de Conservas Garavilla. Technological Analysis of Lithic Support

Presentamos un conjunto lítico recuperado con ocasión de la actividad arqueológica preventiva llevada a cabo en el solar donde se ubicó la fábrica de Conservas Garavilla. Nuestro análisis de las distintas estrategias y métodos de talla de los soportes líticos, sin olvidar la importancia de la secuencia operativa completa, desde la adquisición o selección de las materias primas, con estudio litológico, primeros gestos técnicos, reducción de volúmenes y configuración final de los productos arqueológicos, nos permite adscribir el conjunto al modo técnico 3. Todo ello será valorado en su contexto geológico y geomorfológico, lo que nos ayudará a situar al grupo de cazadores-recolectores protagonista en su medio natural, como integrantes de un proceso histórico vinculado al modo técnico 3.AbstractWe present a lithic ensemble recovered on the occasion of the preventive archaeological activity carried out at the site where the factory of Conservas Garavilla stood. Our research into the different strategies and methods to produce lithic stone tools, without forgetting the importance of the entire operational sequence, from the acquisition or selection of raw materials, with lithologic study, first technical gestures and reduction of volume, to the final configuration of archaeological products, enables us to assign the ensemble to technological mode 3. All this will be considered in its geological and geomorphological context, which will help us to locate the hunter-gatherers protagonist group in its natural environment as part of a historical process connected to what we know as technological mode 3.

The child refugee in Calais: from invisibility to the ‘suspect figure’

This paper examines child refugees in the context of Calais in France, contextualizing them against the politics of the ‘Jungle’ (a makeshift camp) in policy and media discourses in the UK by delineating three distinct phases in the discursive production of these sites in the enactment of this ambiguous entity. These three phases trace the spatio-temporal emergence of the child refugee in the camps to their arrival in the UK. These camps, as transient and symbolic formations inhabited by the ‘dispossessed’ of forced global migration, provide a context in which the figure of the child is enacted from its incidental appearance to its visible manifestation to its final configuration as the ‘suspect figure’ in the UK. Through Derridean ‘hauntology’ of absent presence, the child refugee captures the conflicted morality of the West. As a disenfranchised entity, the child, forged through the turbulence of the Jungle, can be collapsed through the primal and deprived of his or her status as a child (and, in tandem, protection from harm) in public discourses. The child positioned as a ‘suspect figure’ becomes a spectral reflection of the beleaguered West, wrestling with the ideational image of the child and its recurrence as a threat to its moral reserve.