Entanglement, fractional magnetization and long-range interactions

Based on the theory of Matrix Product States, we give precise statements and complete analytical proofs of the following claim: a large fractionalization in the magnetization or the need of long-range interactions imply large entanglement in the state of a quantum spin chain.Comment: 11 pages, 1 figur

The Midpoint Rule as a Variational--Symplectic Integrator. I. Hamiltonian Systems

Numerical algorithms based on variational and symplectic integrators exhibit special features that make them promising candidates for application to general relativity and other constrained Hamiltonian systems. This paper lays part of the foundation for such applications. The midpoint rule for Hamilton's equations is examined from the perspectives of variational and symplectic integrators. It is shown that the midpoint rule preserves the symplectic form, conserves Noether charges, and exhibits excellent long--term energy behavior. The energy behavior is explained by the result, shown here, that the midpoint rule exactly conserves a phase space function that is close to the Hamiltonian. The presentation includes several examples.Comment: 11 pages, 8 figures, REVTe

Fonseca anamnestic index for screening temporomandibular disorders:reliability to discriminate muscular from intra-articular disorders

Introduction - Temporomandibular disorders (TMD) are a set of musculoskeletal and/or articular conditions that affect respectively the masticatory musculature and/or the temporomandibular joint (TMJ) complex. TMD is the most common nondental cause of orofacial pain and have a negative impact on the patient's daily life. The two main origins of pain in this region are considered to be due to intra-articular or masticatory muscle changes. Actually, the diagnosis of TMD is largely based on the patient's symptoms, as pain in TMJ and surrounding muscles, difficulty in opening the mouth, and other complaints such aspresence of clicking in the joint, malocclusion and headaches.The Fonseca Anamnestic Index (FAI) is a TMD patient-reported questionnaire, quick and easy to administer, based in signs and symptoms with 10 questions, used in recent years to classify the severity of TMD. Objectives - The presented study aimed to screen the FAI accuracy to discriminate different types of TMD: intra-articular (AD), Masticatory Muscular Disorders (MMD), or the presence of both typologiesN/

Improving Local Symmetry Estimations in RGB-D Images by Fitting Superquadrics

[Abstract] Real-time manipulation tasks rely on finding good candidates for apprehension points which, in turn, usually requires the computation of local symmetries. When RGB-D images are used as input information, these local symmetries can be deduced from segmenting these images and computing geometric moments for each cluster of points. This approach gives a rough approximation because it does not take into account that the considered points lie on a surface. In this paper, to improve the quality of the symmetry estimations, we propose a simple refinement process that takes as input the estimation obtained using moments and then fits a superquadric to the considered set of points. We evaluate our approach on data collected using a Microsoft's Kinect 2 sensor. The obtained experimental results demonstrate the efficacy of the proposed approach.This work has been partially supported by by the Spanish Ministry of Economy and Competitiveness under projects DPI2014-57220-C2-2-P and DPI2014-57746-C3https://doi.org/10.17979/spudc.978849749808

He I λ 10 830 Å in the transmission spectrum of HD 209458 b

Context. Recently, the He I triplet at 10 830 Å was rediscovered as an excellent probe of the extended and possibly evaporating atmospheres of close-in transiting planets. This has already resulted in detections of this triplet in the atmospheres of a handful of planets, both from space and from the ground. However, while a strong signal is expected for the hot Jupiter HD 209458 b, only upper limits have been obtained so far. Aims. Our goal is to measure the helium excess absorption from HD 209458 b and assess the extended atmosphere of the planet and possible evaporation. Methods. We obtained new high-resolution spectral transit time-series of HD 209458 b using CARMENES at the 3.5 m Calar Alto telescope, targeting the He I triplet at 10 830 Å at a spectral resolving power of 80 400. The observed spectra were corrected for stellar absorption lines using out-of-transit data, for telluric absorption using the MOLECFIT software, and for the sky emission lines using simultaneous sky measurements through a second fibre. Results. We detect He I absorption at a level of 0.91 ± 0.10% (9σ) at mid-transit. The absorption follows the radial velocity change of the planet during transit, unambiguously identifying the planet as the source of the absorption. The core of the absorption exhibits a net blueshift of 1.8 ± 1.3 km s^(−1) . Possible low-level excess absorption is seen further blueward from the main absorption near the centre of the transit, which could be caused by an extended tail. However, this needs to be confirmed. Conclusions. Our results further support a close relation between the strength of planetary absorption in the helium triplet lines and the level of ionising, stellar X-ray, and extreme-UV irradiation

Intervention AUVs: The Next Challenge

While commercially available AUVs are routinely used in survey missions, a new set of applications exist which clearly demand intervention capabilities. The maintenance of: permanent underwater observatories, submerged oil wells, cabled sensor networks, pipes and the deployment and recovery of benthic stations are a few of them. These tasks are addressed nowadays using manned submersibles or work-class ROVs, equipped with teleoperated arms under human supervision. Although researchers have recently opened the door to future I-AUVs, a long path is still necessary to achieve autonomous underwater interventions. This paper reviews the evolution timeline in autonomous underwater intervention systems. Milestone projects in the state of the art are reviewed, highlighting their principal contributions to the field. To the best of the authors knowledge, only three vehicles have demonstrated some autonomous intervention capabilities so far: ALIVE, SAUVIM and GIRONA 500, being the last one the lightest one. In this paper GIRONA 500 I-AUV is presented and its software architecture discussed. Recent results in different scenarios are reported: 1) Valve turning and connector plugging/unplugging while docked to a subsea panel, 2) Free floating valve turning using learning by demonstration, and 3) Multipurpose free-floating object recovery. The paper ends discussing the lessons learned so far

Merbots project: overal description, multisensory autonomous perception and grasping for underwater robotics interventions

[Abstract] The MERBOTS project is, at the moment of writing the present article, in its third year, and have already obtained most of the expected results, from both lab and sea field trials. The project is being coordinated by the Jaume I University (i.e. IRS Lab), jointly with the University of Girona (i.e. CIRS Lab), and University of Balearic Island (i.e. SRV Group). Recent results demonstrate the viability to perform semi-autonomous cooperative interventions in underwater scenarios for archaeological applications. In this paper, first of all an overall description of the project is given, and then some results belonging to the UJI subproject are explained in more detail, such as communications and, in a more detailed manner, the autonomous perception and grasping modules.Ministerio of Economía y Competitividad; DPI2014-57746-C3-1-RGeneralitat Valenciana; GVA-PROMETEO/2016/066Universitat Jaume I; P1-1B2015-6

Silica final lens performance in laser fusion facilities: HiPER and LIFE

Nowadays, the projects LIFE (Laser Inertial Fusion Energy) in USA and HiPER (High Power Laser Energy Research) in Europe are the most advanced ones to demonstrate laser fusion energy viability. One of the main points of concern to properly achieve ignition is the performance of the final optics (lenses) under the severe irradiation conditions that take place in fusion facilities. In this paper, we calculate the radiation fluxes and doses as well as the radiation-induced temperature enhancement and colour centre formation in final lenses assuming realistic geometrical configurations for HiPER and LIFE. On these bases, the mechanical stresses generated by the established temperature gradients are evaluated showing that from a mechanical point of view lenses only fulfill specifications if ions resulting from the imploding target are mitigated. The absorption coefficient of the lenses is calculated during reactor startup and steady-state operation. The obtained results evidence the necessity of new solutions to tackle ignition problems during the startup process for HiPER. Finally, we evaluated the effect of temperature gradients on focal length changes and lens surface deformations. In summary, we discuss the capabilities and weak points of silica lenses and propose alternatives to overcome predictable problems

Multiwavelength optical observations of chromospherically active binary systems. 1. Simultaneous H alpha, Na I D_1, D_2, and He I D_3 observations

This is the first paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. Simultaneous H_α, Na I D_1, D_2, and He I D_3 spectroscopic observations are reported here for 18 systems. The chromospheric contribution in these Lines have been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted H_α profile of some of the more active stars. These profiles are well matched using a two-components Gaussian fit (narrow and broad) and the broad component could be interpreted as arising from microflaring. Prominence-like extended material have been detected in a near-eclipse H_α observation of the system AR Lac. The excess emission found in the Na I D_1 and D_2 lines by application of the spectral subtraction technique and the behaviour of the H_α line in the corresponding simultaneous observations indicate that the filling-in of the core of these lines is a chromospheric activity indicator. For giant stars of the sample the He I D_3 line has been detected in absorption in the subtracted spectra. An optical flare has been detected in UX Ari and II Peg through the presence of the He I D_3 in emission incoincidence with the enhancement of the H_α emission